The Introduction of Chimeric Antigen Receptor T

What is CAR-T?

 

CAR-T refers to chimeric antigen receptor T cell immunotherapy. As a new promising targeted therapy for cancer, CAR-T is precise, fast and efficient. In recent years, it has achieved good results in clinical cancer treatment through continuous optimization and improvement.

T cells, also known as T lymphocyte, are a kind of human white blood cells, derived from bone marrow hematopoietic stem cells. Maturing in the thymus, T cells will migrate to human blood, lymph and surrounding tissues and organs to perform its immune function. They can be regarded as the “warrior” in the human body because they can resist and eliminate “enemies” such as infection, cancer, foreign bodies and so on.

The requirements of target of CAR-T therapy is strict, which are shown as follows:

  1. Being expressed on the cell surface.
  2. This target cannot be found in important organs or cell types (such as hematopoietic stem cells) other than those with tumors. Even low levels of expression may cause serious side effects.
  3. In order to avoid antigen escape, all cancer cells must express the antigen.

The first is easy to understand because of the MHC-independent nature of CAR-T cells. Article 2 is essential for controlling the toxicity of CAR-T cells. Because of the high sensitivity of CAR-T cells, even low levels of antigen expression can trigger T cells to attack the corresponding cells. Article 3 is essential to ensure the effectiveness of CAR-T gene therapy.

It is obvious that CD19 can meet the above three requirements. Besides CD19, some other antigens on the surface of B cells, such as BCMA, can also meet the above characteristics.

BCMA is also an excellent target for CAR-T gene therapy. Although no related products have been approved for market and in clinical trials, CAR-T gene therapy targeting BCMA has achieved great success in the treatment of multiple myeloma.

Controlling toxic reaction

Despite the success of targeted CD19 and BCMA AR-T therapies, toxicity remains a major obstacle.

Severe brain edema is one of the main hazes in the study of CAR-T therapy. Until now, researchers do not have a clear view of the specific mechanism of brain edema. Brain edema is not the only toxic reaction of CAR-T therapy. High-activity reinfusion of CAR-T cells may lead to other serious consequences. CAR-T cells are living drugs, which is different from the traditional drugs. CAR-T cells will expand exponentially when activated by antigens, and cytokines will be released when attacking cancer cells, thus promoting inflammatory response and recruiting more immune cells. If these CAR-T cells attack too quickly, a deadly cytokine release storm will be triggered.

At present, cytokine release storms are generally controllable. In extreme cases, however, severe toxic reactions will be controlled by prompt and rapid removal of CAR-T cells causing toxic reactions..

Suicide switch is a better choice to control CAR-T cells. In the case of severe toxic reaction, the suicide switch on CAR-T cells can be used to induce apoptosis of CAR-T cells quickly and avoid further deterioration of toxic side effects.

Many kinds of suicide switches have been designed by researchers in academic institutions and biotechnology companies. At present, some CAR-T therapies using suicide switches have entered pre-clinical/clinical studies. It is not known whether these suicide switches can effectively control severe toxic reactions, and many people do not think that suicide switches are necessary.

Universal CAR-T

In addition to these biological problems, CAR-T therapy also faces the problem of time and money. Chemotherapy can be widely used in cancer treatment, not only because it can slow down or prevent the progress of cancer, but also because of its high availability, relatively low price, and large-scale preparation, transportation and storage.

Car-T therapy, on the other hand, requires separation of immune cells from blood in the hospital during the preparation of CAR-T cells. After being frozen(some products do not need to be frozen), these separated cells will be transferred to the CAR-T plant. After thawing, viral vectors will be used to transfer genes. Again freeze and transport them to the hospital. Finally, they will be transfused to the patients after thawing.

In addition, it is difficult not only to collect T cells from terminal patients but also to get enough T cells form infants and younger children, which makes it impossible to complete the first step of CAR-T therapy.

In order to make CAR-T therapy into practice, we have to find low-cost ways which are easy to carry out and affordable to patients. A popular way to solve this problem is to use universal CAR-T, that is, to make CAR-T cells from other people rather than patients themselves.

The standard CAR-T treatment process is divided into the following seven steps:

  1. Evaluate whether the patient meets the indications of CAR-T treatment.
  2. Separation of T cells: Mononuclear cells will be isolated from the blood of cancer patients by peripheral blood cell separator, and T cells will be further purified by magnetic beads.
  3. Transforming T cells: Using genetic engineering technology, a viral vector containing chimeric antigen receptors that can recognize and activate T cells is transferred into T cells, i.e. transforming T cells into CAR-T cells.
  4. Expansion of CAR-T cells: A large number of CAR-T cells were cultured in vitro. Generally, a patient needs tens of millions or even hundreds of millions of CAR-T cells. The larger the body weight, the more cells are needed.
  5. CAR-T cells are reintroduced into the human body: Expanded CAR-T cells are reintroduced into the patients via vein, and cancer cell immunotherapy is initiated.
  6. Monitored response: closely monitor the patient’s physical reaction, especially the severe adverse reactions that may occur within one to two weeks after the cell being transported into the body.
  7. Evaluation of therapeutic effect: The therapeutic effect of primary disease will be evaluated on the 15th and 30th day after transfusion of CAR-T cells.

Superoxide Dismutase: material introduction and chemical reaction

Superoxide Dismutase (SOD), alias liver protein, abbreviation: SOD. SOD is an active substance derived from living organisms that can eliminate harmful substances produced by organisms during metabolism. The body’s constant supplementation of SOD has the special effect of anti-aging. Superoxide Dismutase (SOD) is the first time in 1938 that superoxide dismutase was isolated from bovine red blood cells. People have studied SOD for more than 70 years. In 1969, McCord and others rediscovered the protein and discovered their biological activity. They clarified the nature of the disproportionation reaction of peroxy anion, so they were officially named superoxide dismutase.

Material introduction

Superoxide Dismutase (SOD) is a new type of enzyme preparation. It is widely distributed in the biological world, almost from animals to plants, even from humans to single-celled organisms. SOD is regarded as the most magical enzyme in life science and the garbage scavenger in the human body. SOD is the natural enemy of oxygen free radicals, the number one killer of oxygen free radicals in the body, and the basis of life and health.

Super Oxide Dismutase is an important antioxidant enzyme in the body and is widely distributed in various organisms such as animals, plants and microorganisms. SOD has special physiological activity and is the primary substance for scavenging free radicals in living organisms. The level of SOD in the body means a visual indicator of aging and death; it has been confirmed that there are more than 60 diseases caused by oxygen free radicals. It can fight and block the damage caused by oxygen free radicals, and repair damaged cells in time, and damage the cells caused by free radicals. Due to the pressure of modern life, environmental pollution, various radiation and excessive movement will cause a large number of oxygen free radicals; therefore, the role of SOD in biological antioxidant mechanisms is becoming more and more important!

SOD type: superoxide dismutase can be divided into three kinds according to the different metal auxiliary groups. The first one is copper (Cu) zinc (Zn) metal auxiliary group (Cu.Zn-SOD), the most common An enzyme that is green, mainly found in the body’s cytoplasm; the second is a manganese-containing (Mn) metal prosthetic group (Mn-SOD), which is purple, present in mitochondria and prokaryotic cells of eukaryotic cells. The third type is the iron (Fe) metal prosthetic group (Fe-SOD), which is yellowish brown and is present in prokaryotic cells.

Chemical reaction

Superoxide Dismutase (SOD), which catalyzes the following reactions:

2O2-+2H+→H2O2+O2

O2- is called superoxide anion radical, which is an intermediate product naturally formed in various physiological reactions of organisms. It is a kind of active oxygen, has strong oxidizing ability, and is one of the important factors of biological oxygen toxicity.

SOD is a naturally occurring superoxide radical scavenging factor in the body, which converts harmful superoxide radicals into hydrogen peroxide by the above reaction. Although hydrogen peroxide is still a harmful oxygen to the body, the body’s catalase (CAT) and peroxidase (POD) immediately break it down into completely harmless water. In this way, the three enzymes form a complete antioxidant chain.

About Author:

Creative Enzymes is a US-based biotech company that has rich expertise in enzyme manufacturing, such as Catalase, Pectinase, Glucose Oxidase, for life science research and production of medicines, food, alcohol, beer, fruit juice, fabric, paper, leather goods, etc.

The Prerequisites for Genetic Analysis–De Novo Sequencing

A simple introduction of de novo sequencing

 

The sequence was spliced and assembled by bioinformatics analysis to obtain the genome sequence map of the species. A species can be sequenced without any genetic information through this method. At present, de novo sequencing service is widely used to analyze the genome sequence, genetic composition and evolutionary characteristics of unknown species from scratch.

 

Genome de novo sequencing refers to the sequence of a species’ genome which is unknown or without proximal species. Aiming at the different length of genome sequencing DNA fragments and its library, and then biologists use bioinformatics methods for matching, the assembly and annotation, finally obtain the complete genome sequences of map.

The following picture shows protein sequence.

 

Differences between de novo sequencing and re-sequencing

 

Re-sequencing refers to doing genome sequencing in the case of known species genome, aiming at different individuals within the species or different tissues of an individual, Thus, scientists can find the difference between different individuals or tissue cells at the genome level. In this way, we can find out a lot of single nucleotide polymorphism loci (SNP), Insertion loss loci (InDel, Insertion Deletion), Structure mutation loci (SV, Structure Variation) and Copy Number Variation (Copy Number Variation, CNV) Variation etc., so that to obtain the genetic characteristics of biological groups.

 

Take an example here, the virus has a high mutation rate and can be sequenced in the approach of de novo sequencing service instead of re-sequencing.

Method of de novo sequencing

 

In recent years, based on mass spectrometry, high-throughput proteomics has developed rapidly, the use of tandem mass spectra identification of protein is a basic and important link in its data processing. It is de novo sequencing mass spectrometry which can be applied to protein de novo sequencing and also peptide de novo sequencing.

 

Mass spectrometry method to identify the proteins divides into two common analysis methods are the database search and de novo sequencing. The database search is mainly to match the actual mass spectrometry and protein sequences from the database theoretical cracking map. This is the main method of protein identification, which has strong dependence on protein sequence databases. However, de novo sequencing would not be influenced by the error information in protein sequence database. So in this way, under the condition of incomplete information in the protein sequence database, biologists can ever analyze the tandem mass spectrometry data. This technique provides a direct method to explain tandem mass spectrometry data which doesn’t need to use any protein sequence database information. Compared with the database search, de novo sequencing method can analyze the new species or genome tandem mass spectrum data of any species that had not been sequenced before, so that database search method cannot replaced.

Figure: A schematic diagram of protein de novo sequencing

Overall outlook

 

De novo sequencing plays an indispensable role in the data analysis, as the whole genome sequencing and the database is not perfect enough, under this present circumstance, it’s no doubt that analyzing unknown protein sequence in this way is a better choice. However, it has not been widely popularized because of the high demand for data quality and large amount of calculation. In recent years, there have been some other methods and research ideas, but the most perfect effect has not ever been achieved. All in all, there is still a considerably long way to go for improvement in de novo sequencing.

Preclinical toxicology study of new drugs

Definition of toxicology

Toxicology is the science of studying the harmful effects of toxic substances on body and its mechanisms, outcomes, and hazards. It is mainly used for safety evaluation and risk assessment of exogenous substances.

The tasks of drug toxicology include clinical toxicology, new drug clinical trials, and the task of drug epidemiology research. Its basic purpose is to understand and master the toxic effects of drugs, to provide a scientific basis for clinical safe medication and to avoid or mitigate the occurrence of these toxic effects in the course of medication. There are many types of toxic effects, including adverse drug reactions, side reactions, allergies, idiosyncratic reactions, and carcinogenicity.

The importance of preclinical reproductive toxicology research for new drugs

Preclinical safety evaluation is one of the key links in the development of new drugs. The main purpose is to determine the safety characteristics of drug candidates through evaluation, so as to provide experimental basis for further development. However, with the intensification of market competition and the rapid growth of investment in new drug research and development, the current routine safety evaluation methods are no longer sufficient. In addition, due to the increase in the number of new drugs, the country’s requirements for drug safety are also gradually increasing. These phenomena suggest the necessity of preclinical toxicology studies (e.g., vaccine reproductive toxicology study). Preclinical drug toxicology is a new discipline that studies the toxic effects of drugs and its mechanisms, and evaluates the safety of new drugs, including acute toxicity, repeated drug toxicity, safety pharmacology, special toxicity (genotoxicity, reproductive toxicity, carcinogenicity), toxicokinetics and other research. The purpose of the study was to find the symptoms of the toxic reaction of the drug, the duration of the onset and the end, the dose level of non-toxic reaction, the safe range of the dose and the dose of the toxic reaction, the nature and reversibility of the toxic reaction, and the like. The information obtained by the Institute of Drug Toxicology is an important basis for ensuring the safe use of drugs by patients. Therefore, preclinical drug toxicology research is a very important part of the development of new drugs.

What are the preclinical toxicology tests in vaccine development?

A vaccine is a general term for a variety of biological products containing antigenic substances that can induce specific active immunity in the human body. In preclinical studies of new vaccines, it is important to examine the safety of vaccines by conducting preclinical safety assessments of relevant animals. The drug safety evaluation in the preclinical study of new drugs refers to the use of drugs larger than the clinical dose, or longer than the clinical use time, to find and evaluate the potential toxic effects, toxicity performance, and reversibility of target organ damage. This study helps to identify toxic doses, detect toxic effects, determine safe dose ranges, find toxic target organs, and determine the reversibility of toxicity.

The difficulty in drug safety evaluation in preclinical studies of new vaccine drugs is that the vaccine itself does not directly exert its preventive or therapeutic effect, but acts by inducing the immune system to produce antibodies or activate T cells.

What is renal parenchymal hypertension?

What is renal parenchyma? The renal parenchyma can be divided into cortex and medulla, and the cortex is composed of glomeruli and curved tubules. The medulla is composed of 15 to 20 kidney vertebral bodies, and the tip of the kidney cone protrudes into the renal nipple, which is the opening of the nipple tube and the collecting tube. The renal pelvis is funnel-shaped, surrounding 1~3 kidney nipples, and every 2~3 kidneys are combined into one kidney sputum. Generally, the kidney has 3 large sputum, called upper, middle and lower sac, or only there are two big cockroaches. Daxie is synthesized into renal pelvis. Most of the renal pelvis is located in the renal parenchyma, which is called the intrarenal pyelone. Most of it is located outside the renal parenchyma.

Renal substantial hypertension

What is a renal parenchymal disease? It refers to the lesion of the kidney. Such as: substantial kidney hypertension.

Renal parenchymal hypertension refers to an increase in blood pressure in patients due to substantial renal lesions and renal artery disease. In general, more than 90% of patients with renal failure are associated with varying degrees of hypertension. Renal substantial hypertension is a type of secondary hypertension. The clinical symptoms often show that about half of them can hear continuous vasoconstrictory murmurs at specific sites; the course is short, the progress is fast, and the diastolic phase is often accompanied by back pain, no response to drug treatment; symptoms are mostly present before 30 years old or after 50 years old, with sudden or long-term high blood pressure suddenly increasing.

Renal hypertension symptoms

Compared with the same level of essential hypertension, renal parenchymal hypertension is more likely to progress to malignant hypertension than primary hypertension, and the incidence rate is about 2 times higher than that of the latter. Among them, IgA nephropathy, especially hyperplasia or sclerosing IgA nephropathy secondary to malignant hypertension is particularly common. Moreover, compared with primary malignant hypertension, the prognosis of renal malignant hypertension is even worse. According to the authors, the former has a kidney survival rate of 60% in 5 years, while the latter has a kidney survival rate of only 4% in one and a half years.

Fundus lesions of renal parenchymal hypertension are often severe, and cardiac and cerebrovascular complications are often more likely to occur. This is because in addition to hypertension, renal parenchymal disease often has other complex cardiovascular risk factors, such as lipid metabolism disorder in nephrotic syndrome, glucose metabolism disorder in diabetic nephropathy, anemia in renal insufficiency, hyperuricemia symptoms, hyperhomocysteinemia, uremic toxins, metabolic acidosis, and microinflammation, these combined factors will significantly increase the incidence of cardiovascular complications.

Here, special emphasis should be placed on the effects of renal hypertension on the progression of basic kidney disease, especially chronic glomerular disease. In chronic glomerular disease, the anterior glomerular arteriole is in a diastolic state. Systemic hypertension is easily transmitted to the glomerulus, causing glomerular hypertension, hyperperfusion and high filtration. This “three highs” can accelerate the survival. Glomerulosclerosis; at the same time, long-term hypertension can lead to small arteriosclerosis of the kidney, including vitreous changes in the arterioles of the afferents, thickening of the interlobular arteries and the endothelium of the arcuate arteries, narrowing the lumen of the arterioles secondary renal ischemia damage (glomerular ischemic contraction to ischemic sclerosis, tubular atrophy and renal interstitial fibrosis). Therefore, renal hypertension that is not well controlled will significantly accelerate the progression of renal parenchymal disease and form a vicious circle.

The glomerular disease with a large amount of urinary protein and the renal damage of hypertension are more obvious because the effects of the two are superimposed. It is known that proteinuria, especially large amounts of proteinuria, can cause glomerular hypertension, hyperperfusion and hyperfiltration to promote glomerular sclerosis; and, filtered proteins (including complement and growth factors, etc.) and protein-binding Certain substances (including lipids and iron) are reabsorbed by the renal tubules to activate tubular cells and release pathogenic factors (such as transforming growth factor beta) to promote renal interstitial fibrosis. Therefore, in patients with renal hypertensive patients with proteinuria, it is necessary to strictly control hypertension.

Pathological reasons:

A variety of renal parenchymal diseases can cause high blood pressure, and the incidence of hypertension in different renal parenchymal diseases is different.

  1. Unilateral renal parenchymal diseases that can cause hypertension include reflux nephropathy, chronic pyelonephritis, hydronephrosis and renal adenocarcinoma. If the test shows that the renal venous blood renin level is high, it is possible to remove the kidney early. Heal or significantly improve high blood pressure. Hypertension is more common in patients with congenital single kidney deficiency (renal non-development), and acquired single nephrectomy (removal of kidney or donor kidney) does not increase the risk of hypertension, and the mechanism is unclear.
  2. There are many bilateral renal parenchymal diseases that can cause hypertension, including primary and secondary glomerular diseases, chronic interstitial nephritis, and adult polycystic kidney disease. In general, the incidence of hypertension in primary and secondary glomerular diseases is higher than that in chronic interstitial nephritis and adult polycystic kidney disease. In primary and secondary glomerular diseases, pathology is proliferating and/or hardening. The highest incidence of hypertension in the performers. In addition, regardless of which kidney disease occurs when renal function damage occurs, the incidence of hypertension increases. According to the literature, about 90% of patients with end-stage renal disease have hypertension.

Disease diagnosis:

Renal substantial hypertension needs to be differentiated from renal vascular hypertension, renal lesions secondary to hypertension, and other secondary hypertension. Some patients have latent symptoms of kidney disease, and hypertension is very prominent and easily misdiagnosed as essential hypertension.

  1. Renal vascular hypertension:hypertension caused by unilateral or bilateral renal artery trunk or branch stenosis caused by various reasons, common causes are arteritis, fibromuscular dysplasia and atherosclerosis. If there is high blood pressure with the following clinical features, the disease should be suspected: patients who are under 30 years old or over 50 years old have no family history of hypertension; the course of hypertension is short and progresses rapidly, most of them show malignant hypertension; the retina may have Bleeding, exudation, optic disc edema, etc.; vocal murmurs can be heard in the head and neck, upper abdomen and/or lower back ridge area; X-ray and B-ultrasound examinations show differences in size and density of kidneys; renal venous blood test kidneys The activity of the hormone was increased, and the captopril (caprolactam) was positive for the renal chromatogram. Abdominal aorta or selective renal angiography with vascular stenosis can confirm the diagnosis.
  2. Hypertensive kidney disease:Renal substantial hypertension and primary hypertension secondary to renal damage identification, history is very important for its identification. Is high blood pressure first, or proteinuria first, plays a key role in differential diagnosis, the latter diagnosis points are as follows: amore than middle age, more common, may have a family history of hypertension; b before the occurrence of kidney damage has been more than 10 years Hypertension; c slow progression of the disease, tubular dysfunction (decreased urinary function, increased nocturia) earlier than glomerular dysfunction; d mild urine changes (low urine protein, less urinary microscopy); e often accompanied by hypertensive retinopathy, heart and brain complications; f diagnosis of this disease still need to exclude a variety of primary and secondary kidney disease. Renal biopsy is feasible when clinical diagnosis is difficult. Renal tissue pathology is helpful for differential diagnosis.
  3. Other secondary hypertension: 1 Endocrine hypertension: hypercortical hyperemia occurs in endocrine disorders such as hypercortisolism, pheochromocytoma, primary aldosteronism, hyperthyroidism, and menopause. Corresponding diagnosis can be made according to the endocrine history, special clinical manifestations and endocrine test. 2 aortic coarctation, congenital aortic coarctation or multiple arteritis caused by descending aorta and abdominal aortic stenosis, can lead to high blood pressure. Clinical features often have high blood pressure in the upper limbs and low blood pressure in the lower limbs; the abdominal aorta, femoral artery and other lower extremity arteries are weakened or inaccessible; the interscapular region, the ankle and the middle and upper abdomen may have pulsation of the collateral circulation artery. , tremors and murmurs; signs of left ventricular hypertrophy and dilatation. 3 craniocerebral lesions: some encephalitis or tumor, intracranial hypertension and other common hypertension, the neurological manifestations of this type of lesions are more characteristic, the diagnosis is generally not difficult. 4 pregnancy-induced hypertension syndrome: more than 3 to 4 months after the third trimester of pregnancy, childbirth or 48 hours after delivery, characterized by high blood pressure, edema and proteinuria, severe convulsions and coma.

Compare endothelial cells and epithelial cells and their differences

Endothelial cells cover the inner surface of the blood vessel, and epithelial cells cover the inner surface of the internal organs. The epithelial cells also cover the outer surface of the human body. If a large number of epithelial cells are found in the urine during urine testing, it indicates a urinary tract infection.

The endothelial cells and epithelial cells that make up the tissue are derived from the epithelium, but the two are different in location, structure, and function (as the table). In addition, both cells form the interface between the inner and outer environments. Endothelial cells are located “inside” the body, such as the interior of blood vessels, while epithelial cells are often described as covering the “outside” of the body, such as the outer layer of the skin (epidermis, epidermis).

Comparison of endothelia cells and epithelial cells:

Items Endothelial cells Epithelial Cells
Location Endothelial cells form endothelium, a thin layer that covers the inner surface of the blood vessel. Briefly, the cells cling to the blood vessel wall. Therefore, the inner wall of the entire circulatory system is covered by endothelial cells. These cells form the interface between the blood vessel wall and the blood. They close to the inner surface of the heart. They are a thick layer of single cells. The epithelial cells that make up the epithelial tissue cover not only the outer surface of the body, but also the outer surface of all internal organs of the body. For example, the epidermis of the outermost layer of the skin is the epithelial cell. The skin on the surface is thus covered by epithelial cells, which provide a protection for the body. Epithelial cells also cover the surface of internal organs, such as the liver, stomach, intestines, lungs, urethra, bladder, and the like. In other words, epithelial cells cover the surface and internal tissues of the body.
functions Endothelial cells covering the vessel wall regulate blood flow in the blood vessels, which release NO. NO is a vasodilator that promotes blood circulation and helps control blood pressure. Endothelial cells can also secrete a variety of proteins that cause blood disorders, but they also stop bleeding. The inside of the glomerulus contains endothelial cells, which act to filter blood. The epithelial cells that make up the skin protect the subcutaneous tissue from damage, bacterial intrusion, dangerous chemicals, and avoid excessive loss of moisture. When necessary, the skin’s epithelial cells also secrete sweat to regulate body temperature. Epithelial cells covering the pancreas secrete enzymes to promote digestion. In addition, epithelial cells on the surface of the small intestine absorb nutrients from the digested food. Epithelial cells on the surface of the respiratory tract form mucous membranes that secrete mucus to prevent inhaled bacteria and viruses from entering the lungs. Specialized epithelial cells are secreted on organs that are in contact with nerve endings such as skin, nose, tongue, eyes, etc., which recognize sensory stimuli. In summary, the main functions of epithelial cells involve secretion, absorption, and protection.
Features The endothelial cells that make up the endothelial tissue are monolayer structures, and water molecules and oxygen molecules easily pass through the endothelial cells and enter the tissues surrounding the endothelial cells. In addition, endothelial cells lack a packed epithelial morphology, and there are gaps between endothelial cells, which contribute to the passage of liquids and the diffusion of substances. The epithelial cells that make up the epithelial tissue have a variety of structures to protect the body from the external environment. Epithelial cells are tightly bound, similar to bricks, with few gaps between cells.
Intermediate Filaments Some proteins, referred to herein as intermediate filaments, support the cells and form the shape of the cells. Simply speaking, the intermediate filaments provide the cellular structure. Endothelial cells contain vimentin filaments. Keratin filaments provide the structure of epithelial cells.
Surface layer The surface of endothelial cells is a non-thrombogenic, soft surface that does not coagulate during normal blood circulation. Epithelial tissues composed of different types of epithelial cells exhibit irregular papillary projections.

Schematic diagram of endothelial cells (Figure 1) and epithelial cells (Figure 2):

Endothelium is a kind of epithelium. The endothelial cells are distributed on the inner surface of the blood vessels. In the lumen, the endothelial tissues form the interface between the circulatory system or the lymphatic system and other parts of the blood vessels. The structure is as follows:

Figure 1. Schematic diagram of endothelial cells

Figure 2 shows the morphology of epithelial cells. Epithelial cells can be arranged in a single layer of cell structure, or in two layers, or even a multi-layered cell structure. As shown in Figure 2, all glands are composed of epithelial cells. The function of epithelial cells includes secretion, absorption, protection, and transmembrane transport.

Figure 2. Morphology of epithelial cells

Introduction to Transferase

Transferases are a class of enzymes that transfer specific functional groups from one molecule (donor) to another (acceptor). Transferases are implicated in hundreds of different biochemical pathways, and are essential to some of most important processes in lives. Transferases participate in a myriad of cell reactions and are also utilized during translation. Mechanistically, an enzyme catalyzing the following reaction would be considered as a transferase:

Figure 1. Redox reaction.

where X is the donor that is often a coenzyme, and Y is the acceptor. Group would be the functional group that is transferred on account of transferase activity.

Nomenclature

Systematic names of transferases are based on the form of “donor:acceptor grouptransferase.” For example, methylamine:L-glutamate N-methyltransferase is the normative name for the transferase methylamine-glutamate N-methyltransferase, where methyltransferase is the EC category, methylamine is the donor, and L-glutamate is the acceptor. Nonetheless, the more frequently used nomenclature for transferases are often in a form of “acceptor grouptransferase” or “donor grouptransferase.” Practically, many molecules are not mentioned by taking advantage of this terminology because of the application of more prevalent common names.

History

It occurs as early as the 1930s that some of the most important transferases were discovered. Transamination that means the transfer of a NH2 group from an amino acid to a keto acid through an aminotransferase is noticed for the first time in 1930 after the disappearance of glutamic acid appended to pigeon breast muscle, which is subsequently confirmed by the discovery of its reaction mechanism in 1937. This reversible reaction could be also applied to other tissues, which lays the basis for the possibility that their similar transfers act as a main choice of producing amino acids via amino transfer. Later in 1953, enzyme UDP-glucose pyrophosphorylase is revealed to be a transferase, since it is found to be capable of reversibly generating UTP and G1P from UDP-glucose and an organic pyrophosphate. Another historically significant discovery in transferase is illumination of the breakdown mechanism of catecholamine by catechol-O-methyltransferase, which accounts a large part for Julius Axelrod’s 1970 Nobel Prize in Physiology or Medicine.

Classification

Up to now, the classification of transferases is still under way for new ones discovered frequently. The category of transferases is described primarily according to the type of biochemical group transferred, and can be divided into ten groups based on the EC Number classification, which comprises more than 450 different unique enzymes and have been assigned a number of EC 2 in the EC numbering system. Hydrogen is not recognized as a functional group when it refers to transferase targets. On the contrary, hydrogen transfer is divided into oxidoreductases in consideration of electron transfer.

EC number Description
EC 2.1 Single carbon transferases under EC 2.1 are enzymes that transfer single-carbon groups, which contain functional groups of hydroxymethyl, methyl, carboxy, carbamoyl, formyl, and amido substituents.
EC 2.2 EC 2.2 includes aldehyde and ketone transferases transferring aldehyde or ketone groups, mainly comprising a variety of transketolases and transaldolases that play important role in pentose phosphate pathway and catalyze the transfer of dihydroxyacetone functional group to glyceraldehyde 3-phosphate.
EC 2.3 Acyl transferases as key aspects of EC 2.3 could transfer acyl groups or acyl groups that are converted into alkyl groups during the process of being transferred. Furthermore, this category also distinguishes amino-acyl from non-amino-acyl groups.
EC 2.4 Enzymes divided into EC 2.4 could transfer glycosyl, hexosyl and pentosyl groups. Glycosyltransferase under the subcategory of EC 2.4 takes participate in the biosynthesis of disaccharides and polysaccharides by transferring monosaccharides to other molecules.
EC 2.5 Currently, EC 2.5 only possesses enzymes that are involved to transferring alkyl or aryl groups, which yet do not include methyl group. This is different from functional groups that are transformed into alkyl groups when transferred.
EC 2.6 EC 2.6 is a group of enzymes that are consistent with transfer of nitrogenous groups, including transaminase, oximinotransferases and other nitrogen group transferring enzymes. Amidinotransferase is previously grouped into EC 2.6, while it has recently been reclassified as a subcategory of EC 2.1.
EC 2.7 EC 2.7 consists of not only enzymes that transfer phosphorus-containing groups, but also nuclotidyl transferases. Subcategory of phosphotransferase is further divided in accordance with the type of group experiencing the transfer. Phosphate acceptors mainly include alcohols, carboxy groups, nitrogenous groups, and phosphate groups. Various kinases are also constituents of this subclass of transferases.
EC 2.8 Sulfur transferases transferring sulfur-containing groups are covered by EC 2.8 and are further subdivided into the subcategories of sulfurtransferases, sulfotransferases, and CoA-transferases, as well as alkylthio groups transferring enzymes. Some specific sulfotransferases could employ PAPS as a sulfate group donor, within which alcohol sulfotransferase has a broad targeting capacity. Therefore, alcohol sulfotransferase is also acknowledged as “steroid sulfokinase,” “hydroxysteroid sulfotransferase,” and “estrogen sulfotransferase.” Decrease in the activity has been concerned with human liver disease.
EC 2.9 Selenium transferases belong to EC 2.9 and only contain two transferases, which therefore is one of the smallest categories of transferase.
EC 2.10 The class of EC 2.10 covers enzymes transferring molybdenum or tungsten-containing groups. However, only one enzyme molybdopterin molybdotransferase, a component of MoCo biosynthesis in Escherichia coli, has been added until 2011.

Applications in Biotechnology

Terminal transferase is one of the few DNA polymerases functioning without an RNA primer, and could label DNA or produce plasmid vectors by adding deoxynucleotides in the form of a template to the downstream end or 3′ end of an existing DNA molecule.

Glutathione transferases with high diversity can be applied by plants to segregate toxic metals from the rest of the cell, which thus can be processed as biosensors to detect contaminants such as herbicides and insecticides. Glutathione transferases could also increase resistance to both biotic and abiotic stress in transgenic plants, and now they are being explored as targets for anti-cancer medications owing to their functionality in drug resistance. Currently the only available commercial source of natural rubber is the Hevea plant.

Article source: https://www.creative-enzymes.com/resource/Transferase-Introduction_20.html

Biomarker: Active Pioneer in Medicine Fields

With the development of bioscience, biomarkers are widely used in medicine. Biomarkers are indicators that can judge the occurrence, development and prognosis of diseases. They can be used for the diagnosis and classification of diseases, monitoring the disease development and severity, testing the effect of clinical treatment, predicting an individual’s risk of disease and the screening of high-risk groups. The selection of biomarkers requires strict clinical validation and the feasibility of using biomarkers in specific clinical situations. Nowadays the biomarker development has made the application gradually change from simplification to combination. The combined application of biomarkers and other detection methods is conducive to the early, rapid and accurate diagnosis of diseases, thus providing a basis for clinical treatment.

As can be seen from the definition of biomarkers, biomarkers cover a wide range, and with the progress of detection technology, more specific detection results can be regarded as biomarkers. Here we will introduce 4 biomarkers that are widely used below:

  1. HE4

HE4 is human epididymal protein 4, first found in epithelial cells at the distal end of human epididymis. It consists of two core structures: a 25KDa natural n-terminal glycosylated protein and two whey acidic protein core regions (WAP, consisting of four disulfide bond core regions and eight cysteine residues). The gene encoding HE4 has multiple homologous brothers and also codes for the WAP core protein.

For example, SLPI and Elafin, both of which have protease inhibitory and anti-inflammatory effects, are associated with host resistance to bacterial infection. It was on the basis of “brotherly similarity”, their sibling protein, HE4, was initially identified as having anti-inflammatory and antibacterial properties. Since it is found in epididymal epithelial cells of humans, it is speculated that HE4 may be a protein-inhibiting enzyme involved in reproductive development. With the reveal of follow-up studies, the true nature of HE4 began to emerge. Subsequent studies found HE4 tumor marker expression in tumor cell lines, opening a new window of clinical cognition.

  1. HER2

Currently, the commonly used markers in clinical diagnosis, treatment and monitoring of breast cancer are mainly CA153, CA125, CEA and Her2. HER2, which is considered as a potential marker of breast cancer, has attracted more and more attention. HER2, also known as human epidermal growth factor receptor-2, is a major oncogene responsible for breast cancer. In clinical practice, the determination of whether the expression of HER2 is positive can be used to formulate treatment plans for different types of breast cancer patients.

For the detection of HER2 marker, immunohistochemistry is often used. With the development of science and technology, the serological detection method of HER2 came into being, which has the advantages of convenience, rapidity and feasibility. The detection of HER2 in serum and in tissue can be complemented by each other, so as to more accurately determine the expression state of HER2. It can also be used for monitoring the therapeutic effect of targeted drugs, dynamic follow-up observation and indication of prognosis. Therefore, the detection of serum HER2 level has fully demonstrated its great advantages. As a “potential stock”, it has been recognized by clinicians, bringing significant effects for the treatment of breast cancer.

  1. PCT

PCT (procalcitonin) is a protein that is elevated in plasma during severe bacterial, fungal, and parasitic infections as well as sepsis and multiple organ failure. PCT does not increase with autoimmunity, allergy, or viral infection.

It reflects the level of activation of inflammatory responses throughout the body. Factors that affect PCT levels include the size and type of organ being infected, the type of bacteria, the level of inflammation, and the state of the immune response. In addition, PCT marker can only be detected in a small number of patients 1 to 4 days after major surgery.

  1. ST2

ST2 marker is a myocardial protein produced by cardiac myocytes under biomechanical stress. It is a soluble protein expressed in response to heart disease or injury, and reflects ventricular remodeling and cardiac fibrosis related to heart failure. Studies have shown that the concentration of ST2 is related to the severity of heart failure, left ventricular ejection fraction, brain natriuretic peptide (BNP), type B brain natriuretic peptide precursor (NT-proBNP) and creatinine clearance rate, but not age, previous history of heart failure, history of atrial fibrillation and body mass index. And BNP, NT-proBNP is often affected by these factors, therefore, ST2 combined with them determination can improve the accuracy of assessing the prognosis of heart failure. Meanwhile, recent studies have shown that ST2/ IL-33 signaling pathway plays an important role in the processes of asthma, autoimmune diseases, anti-atherosclerosis, anti-myocardial fibrosis and myocardial cell hypertrophy.

Biomarkers are powerful tools for ivd assay. With the progress of detection technology, the introduction of more ideal statistical analysis methods or algorithms, the use of larger and more comprehensive case samples and the deepening of people’s understanding of the details of life activities, more and more ideal biomarkers will be found and applied in clinical practice.

Wholesale Supply Chains in Business

Most merchants will testify to the fact that supply chains are often the most important factor in delivering products to their destination. Merchants that are capable of understanding this will reap all the benefits of an expanding market. If you can secure your own marketing model, then the supply chain will ensure that you do not run out of products to put out onto the market. Drop shipping is one of those areas where the supply chain will play a crucial part in the level of success that the merchant can expect.

Solutions for merchants

Some merchants have decided to buy their products wholesale from China in order to ensure that they have a constant stream of items to put on the market. China is the workshop of the world. They seem to have an inescapable capability to produce everything and anything. That means that the merchant simply has to run down the list of items that are on sale and then make an offer. In most cases this will translate into instant profits. Some people are convincingly argued that the presence of different marketing forums means that the supply chains can be changed if there are bottlenecks.

That is certainly true if you are dealing with the Chinese market. Here the merchant can lay down some specifications which are conditions for the business relationship. If these conditions are not met then the merchant is well within their rights to find alternative sources of products. That can help to keep the merchant in line as well because they have to monitor supply chains. For example you will need to watch the journey of a wholesale Tablet from the time an order is made to the time that delivery is completed. The merchant will be getting regular updates on the progress of the order so that they can clear up any difficulties.

What makes supply chains difficult?

Often stock control or the lack of it is the problem. Some manufacturers are not very clear about their capacity. Therefore they will accept orders that cannot be easily fulfilled. This is very frustrating for the merchant because they have to turn round and appease an irate customer. The best solution is to limit orders to the capacity that the supplier has. In order for this to happen, the supplier has to be candid about the limitations of the chain. They should be able to turn down orders in advance if the capacity is just not there.

Import Express is a wholesale online site from China. Find cheap import products at wholesale price, including Clothing, Mobile Phone, Computers, Jewelry, Beauty, Sports, Home decor and so on, Shopping on Import-express For Small Businesses now.

Import Express is supposed to be the first priority for new comers. They have global reach servicing customers in more than over 200 countries.

Import Express, a B2B based wholesale website. Since 2005, Import express has played a critical role in helping more retailers grow faster around the world. As an experienced end-to-end wholesale solution company, Import-express provides professional wholesale and drop ship service. The website continue to provide high-quality wholesale business service that empowers retailers to do more business all over the world.

It offers full catalogs, including children’s boutique clothing, sunglasses, shoes, clothes, jewelry and accessories, beauty, 3C products, household necessaries and so on that totally more than 500,000+ SKU. Also, new and trendy arrivals added every day.

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Terms about structure and function of antibodies

  1. Antibody

An antibody refers to a protective protein produced by the body due to stimulation of an antigen. It is a large Y-shaped protein secreted by plasma cells (effector B cells) that is used by the immune system to identify and neutralize foreign substances such as bacteria, viruses, etc. Antibodies can recognize a unique feature of a particular foreign object (an antigen).

  1. Antibody engineering

Antibody engineering refers to the process of transforming and reassembling antibody genes by using recombinant DNA and protein engineering techniques, expressing antibody molecules after transfecting appropriate recipient cells, or modifying antibody molecules by cell fusion or chemical modification. These antibody engineered antibody molecules are novel antibody molecules that are reassembled according to human design, which can retain (or increase) the specificity and major biological activity of natural antibodies, remove (or reduce or replace) irrelevant structures.

  1. Immunoglobulin (lg)

An immunoglobulin has an antibody activity and similar chemical structure to an antibody.

  1. Functional region

The H chain and L chain of the lg molecule can be folded into several spherical structures by intrachain disulfide bonds, and each spherical structure consists of 110 amino acids, which has a certain physiological function and is called a functional region, also called the domain.

  1. Variability

The variability of a position is the ratio of the number of different amino acids present at that position to the frequency of occurrence of the most frequently occurring amino acid residues at that position.

  1. Immunoglobulin superfamily (IGSF)

IGSF is a collection of molecules containing immunoglobulin folded structurally-like functional region. Most members of the lg molecular superfamily are cell membrane surface molecules.

  1. Classification according to the antigen characteristics of immunoglobulin

1) Isotype: refers to the antigen specificity of antibodies shared by all individuals in the same species, present in the constant region. Isotype antigen specificity varies by species, mainly including lg class, industry, type and business type.

2) Allotype: refers to the different antigen specificity of lg molecules between individuals of the same genus. As a genetic marker, there is a constant region of lg.

3) Unique type: each antibody forms an antigen specificity specific to the antibody molecule produced by the cell clone. It is determined by the difference in the amino acid sequence of the VH or VL variable region. It is closely related to the specificity of the antibody-binding antigen.

  1. CDR epitopes

VH and VL are tightly bound together to form a dense globular structure, which becomes the Fv segment. The six CDRs are located at the N-terminus of the Pv segment and are called CDR surfaces, ie, antigen binding sites.

  1. Binding force

The combination of antigen and antibody depends on electrostatic attraction, hydrogen bonding, van der Waals force, etc., and requires suitable temperature, pH, ionic strength and intact antibody. This combination is reversible.

  1. Antibody-dependent cell cytotoxicity (ADCC)

The antibody molecule binds to the surface of the target cell and can be combined with the Fc receptor on the surface of the killer cell to promote the pair. The killing effect of target cells is called ADCC. Mononuclear macrophages, neutrophils and NK cells have ADCC effect.