Friday, November 29, 2013

Online course: DNA - From Structure to Therapy

Join this free online course on DNA-From Structure to therapy

iversity logo
A course by Dr. rer. nat. habil. Susanne Illenberger and Prof. DPhil. Sebastian Springer
Jacobs University Bremen

Course description:

This course explains one of the key molecules in life: DNA, which stores the genetic information in all living cells. The sequence of its building blocks defines both individual identity and species diversity. Changes in DNA can lead to cancer and other diseases. DNA-based technology is now used to detect and treat diseases.

Thursday, October 10, 2013

2013 Nobel Prize in Chemistry

Nobel prize winners for 2013

Martin Karplus, photo © Harvard University. Michael Levitt, photo: S. Fisch. Arieh Warshel, photo: Wikimedia Commons

Tuesday, October 1, 2013

Dementia in Mid-life

Mid-life stress 'precedes dementia'

The study only looked at women, not men.

Mid-life stress may increase a woman's risk of developing dementia, according to researchers.

In a study of 800 Swedish women, those who had to cope with events such as divorce or bereavement were more likely to get Alzheimer's decades later.

The more stressful events there were, the higher the dementia risk became, BMJ Open reports.

Monday, September 30, 2013

Risk factor for early childhood death

Young mothers 'risk factor for early childhood death'

Children born to mothers under 30 are more likely to die than those born to older mums, a report on child deaths in the UK suggests.


While overall child mortality fell by 50% in the past 20 years, young maternal age was found to be a risk factor for death in early childhood.



Support should be extended to mothers of all ages, not just first-time teenage mums, the report said.


Thursday, September 26, 2013

Promising results on Type 1 diabetes : Skin drugs

Skin drug shows 'promising' results on type 1 diabetes

A drug that was used to treat a skin disorder has shown signs of being able to treat aspects of type 1 diabetes. A small trial on US patients suggests that alefacept helps the body produce its own insulin, which is key for people with type 1 diabetes. Type 1 diabetes affects around 400,000 people in the UK.

Researchers said the drug could be better than other treatments because it protects the immune system - but more research was needed.

Universal flu vaccine : Great steps of scientific discovery

Scientists take big step towards universal flu vaccine

Scientists say they have made a significant leap towards creating a vaccine that would protect against every form of flu. The influenza virus is a constantly shifting target so seasonal flu vaccines rapidly become useless and new ones are needed each year.

A team at Imperial College London say they have made a "blueprint" for a universal flu vaccine. Their discovery is published in the journal Nature Medicine. Influenza is able to change the proteins that protrude from the surface of the virus as readily as people change outfits. However, the material on the inside is common

Type 2 Diabetes and Anti-depressants

Anti-depressants 'linked to type 2 diabetes'

People prescribed anti-depressants should be aware they could be at increased risk of type 2 diabetes, say UK researchers.
The University of Southampton team looked at available medical studies and found evidence the two were linked.
But there was no proof that one necessarily caused the other.
It may be that people taking anti-depressants put on weight which, in turn, increases their diabetes risk, the team told Diabetes Care journal.
Or the drugs themselves may interfere with blood sugar control.

Wednesday, September 25, 2013

RBC Metabolism Notes (Part 5) : Role of Vitamin B12 and Pernicious anemia

COBALAMIN (Vitamin B12)

  • Vitamin B12 is required in humans for two essential enzymatic reactions: the synthesis of methionine and the isomerization of methylmalonyl CoA that arises from the fatty acids with odd numbers of carbon atoms (Fig 28.10).
  • When the vitamin is deficient, abnormal fatty acids accumulate and become incorporated into cell membranes, including those of the nervous system. 

RBC Metabolism Notes (Part 4) : Maturation of RBC and role of Folic acid

MATURATION OF RBC - ROLE OF FOLIC ACID & VITAMIN B12 IN DNA SYNTHESIS

 

FOLIC ACID

  • Folic acid (or folate) plays a key role in one-carbon metabolism, and is essential for the biosynthesis of the purines and the pyrimidine, thymine. 
     
  • Folic acid deficiency is probably the most common vitamin deficiency in the U.S., particularly among pregnant women and alcoholics.

Structure of Folic Acid

  • Folic acid is composed of a pterin ring attached to p-aminobenzoic acid (PABA) and conjugated with one or more glutamic acid residues.

RBC Metabolism Notes (Part 3) : Energy metabolism


ENERGY METABOLISM
  • Although the mature red cell contains the enzymes required for glycogen metabolism, the balance between synthesis and utilization is such that no significant amount of glycogen accumulates within the cell under normal circumstances. 

  • Glycogen may accumulate, however, in glycogen storage diseases types III and VI.

RBC Metabolism (Part 2) : Mechanisms of preventing oxidative denaturation of hemoglobin

  • Fig. Enzyme that converts MetHb to Hb
    Known mechanisms of preventing or reversing oxidative denaturation of hemoglobin in the erythrocyte include 
    • the methemoglobin reductases
    • superoxide dismutase
    • glutathione peroxidase
    • catalase.
(Fig. in left NADH_cytochrome_B5_reductase)
Methemoglobin Reduction
  • Most methemoglobin in the erythrocyte is reduced through the action of an enzyme cytochrome b5 methemoglobin reductase, which acts in the presence of two electrons carriers, cytochrome b5, and NADH.

Tuesday, September 24, 2013

RBC Metabolism Notes (Part 1) : Stages of oxidative denaturation of Hemoglobin

OXIDATIVE DENATURATION OF HEMOGLOBIN: IT’S REVERSIBILITY AND PREVENTION

INTRODUCTION

  • Oxyhemoglobin in solution gradually undergoes autoxidation, becoming methemoglobin (HbFe+++).
  • The rate of oxidation is enhanced by conditions such as increased temperature, decreased pH and presence of organic phosphate and of metal ions, and partial oxygenation of hemoglobin. To bind oxygen reversibly, however, the iron in the heme moiety must be maintained in the reduced (ferrous Fe++) state, despite exposure to a variety of

Monday, September 16, 2013

Neurotransmitter : Overview and Functions

What are Neurotransmitters?  How do they affect your life?
Just like hormones govern many chemical functions in the body, the brain's chemical functions are governed by messengers called neurotransmitters.

Fig. Neurosynaptic transmission
A neurotransmitter is a chemical messenger used by neurons (nerve cells) to communicate in one direction with other neurons. These neurotransmitters are either excitatory or inhibitory. Each cell receives its instructions through nerve processes called dendrites and it passes on instructions to the next cell through its axon. The gap between the axon of one cell and the dendrite of the next is called a synapse.

Special molecules in the dendrite are called receptors. They are shaped to receive only one type of neurotransmitter, which fits it like a key in a lock. The result is that if an excitatory

Thursday, September 12, 2013

Alternative to nicotine patches: E-cigarette

E-cigarettes 'as effective' as nicotine patches

Electronic cigarettes appear to be at least as effective as nicotine patches in helping people to give up smoking, research suggests.
Fig. E-cigarette (Courtesy: ecigaretteuser.com)
The devices, which are rapidly growing in popularity, produce a vapour containing nicotine.
The findings, presented at the European Respiratory Society, showed similar numbers quitting with e-cigarettes as patches, but more had cut down.
There was a call, however, for long-term data on safety.

Testicle size 'link to father role'

A link between the size of a father's testicles and how active he is in bringing up his children has been suggested by scientists.
Researchers at Emory University, US, said those with smaller testicles were more likely to be involved with nappy changing, feeding and bath time.
They also found differences in brain scans of fathers looking at images of their child, linked to testicle size.
But other factors, such as cultural expectations, also played a role.
Levels of promiscuity and testicle size are strongly linked in animals, those with the largest pair tending to mate with more partners.

The researchers were investigating an evolutionary theory about trade-offs between investing time and effort in mating or putting

Tuesday, September 10, 2013

Cancer gene testing : BRCA1 and BRCA2 genes

Explaining Jolie's cancer:

News of Angelina Jolie's decision to undergo a prophylactic double mastectomy has instantly increased awareness of hereditary forms of cancer caused by mutations in the BRCA1 and BRCA2 genes.

Fig. Actress Angelina Jolie
While the BRCA1 and BRCA2 genes were discovered in the mid-1990s, genetic testing for the genes is increasingly available. Jolie's case highlights the importance of knowing one's family history and learning one's cancer risks in order to address them proactively.

Everyone has the BRCA1 and BRCA2 genes. We have two copies of each gene and get one each from our mother and father. They play a role in protecting the body against the development of cancer.

Individuals with mutations in either of these genes have increased cancer risks, most notably for breast and ovarian cancer. Individuals with mutations in BRCA1 and BRCA2 benefit from tailored management aimed at reducing cancer risks and detecting cancers early when they are most treatable.

Friday, September 6, 2013

Interpreting and Correlating Abnormal Laboratory Values : Cardiac Function Tests

Diagnosis of Myocardial Infarction (MI) and Acute Coronary Syndrome

Fig. Getting MI attack
Since acute MI (AMI) requires rapid and accurate diagnosis, especially now that new treatment options with thrombolytic agents are available, the clinical laboratory has been called upon to provide serum diagnostic tests that can make this diagnosis at an early stage. Until recently, laboratory diagnosis was based on serial determinations of the MB fraction of creatine phosphokinase (CK-MB); confirmation of the diagnosis was provided by the so-called ‘flipped ratio’ of the isozymes of lactate dehydrogenase (LD) 24-36 hours after the initial acute event and/or by observation of the characteristic time courses for elevations of the three enzymes, CK, aspartate aminotransferase (AST) and LD.

Interpreting and Correlating Abnormal Laboratory Values : Liver Function Tests

The most common liver test abnormalities can be summarized to a set of six conditions as in Table 1. The principles for these patterns are explained as follows.
  
1.   
All acute injuries and/or necrotic lesions in the liver primarily cause a marked rise in the levels of the aminotransferases, aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Cell injury and necrosis also cause the rise of other enzymes such as lactate dehydrogenase (LD). These include acute hepatitis

Thursday, September 5, 2013

Interpreting and Correlating Abnormal Laboratory Values : Electrolyte Abnormalities


Electrolyte Abnormalities
Hyponatremia

The four most common causes of hyponatremia are given in Table 1 (See below), together with a fifth, rare, cause, Bartter's syndrome. A sixth, metabolic cause, diabetes mellitus, is also presented in this table. In all forms of hyponatremia, the chloride ion concentration is also generally low since chloride is the chief counter-ion for sodium.

Interpreting and Correlating Abnormal Laboratory Values : Glucose Abnormalities

The major purpose of performing analyte determinations in the clinical laboratory is to aid in the diagnosis and management of patients with disease and individuals in health assessment. In this regard, the clinical pathologist/Clinical Biochemist/Clinical Microbiologist are often called upon as a consultant to explain abnormal laboratory values, especially those that do not seem to correlate with one another, and to recommend or even to order laboratory tests that may lead to the correct diagnosis in the work-up of patients for particular medical problems.

POCT : Point of Care testing - Introduction, Utility and Management

Point-of-care testing (POCT) is an emerging concept in laboratory medicine and has attracted considerable interest in the medical literature. Recent experience has revealed a variety of applications for these new technologies in

Tuesday, July 2, 2013

Tumor marker : Introduction, Classification and Clinical application

Introduction:

The first tumor marker reported was the Bence-Jones protein (monoclonal light chains of Ig secreted by tumor plasma cells) by precipitation in acidified boiled urine and is the diagnostic marker of multiple myeloma. It was identified by H. Bence-Jones in 1846. The second era (1982-1963) was the discovery of hormones, enzymes, isoenzymes and proteins

Monday, July 1, 2013

How to study Biochemistry ?

Biochemistry is often cited as a challenging, high-volume course that revolves around complex molecular relationships and multi-step reactions.  Successful students must have a strong understanding of the concepts and solid memorization techniques to succeed in this course.  The following study strategies and tips have been formulated from past students that succeeded in their courses to help you learn how to study Biochemistry.

Study Skill #1 - Do NOT procrastinate.  The most obvious, and yet least followed advice by students.  Biochemistry is a high-volume course that progresses and builds its concepts on the fundamentals.  Moreover, many pathways and reactions require memorization and must be acquired over time.

Study Skill #2 - Start with the big picture.  There is no doubt that you will have to memorize multi-step metabolic pathways.  The best way to do this is to start with the big steps and understand the overall flow of the reaction.  First, write only the substrates and products in order.  Do this repeatedly, until it is memorized.  Then add the enzymes.  Then continue to  add co-factors and by-products.  If necessary, label each as an exer- or endergonic reaction and whether or not it is reversible.  Check out Lippincott's Illustrated Reviews: Biochemistry Book for an easy-to-understand approach and large full-color illustrations.  Use the nomenclature to help you remember what is going on in each step. For example, Phosphofructokinase-1, adds a phosphate group (phospho-kinase) to the molecule fructose (-fructo-) at the first position (-1).  By breaking down the pathways and focusing on the terminology it will greatly speed up your ability to memorize them.

Study Skill #3 - Know the terminology and nomenclature, it will make things much easier down the road.  An enzyme or protein will often have its function built into its name.  Take Protein Kinase A for example.  As a member of the Kinases, it will almost always add a phosphate group to its substrate.  Or, take Alcohol Dehydrogenase, structures that are Dehydrogenases always oxidize a substrate.  In this case, it oxidizes alcohols into aldehydes and ketones.  Once you get this down, you will begin to recognize names and automatically correlate them with a specific function.

Study Skill #4 - Buy a dry erase board.  Use this to memorize the pathways and any other reactions you have to know.  There are no short-cuts, but writing things out reinforces them in your memory.  It tends to be much more efficient than staring and reciting from your textbook.

Study Skill #5 - Know the purpose of a reaction. Take the Bohr Effect for example.  An increase in [H+] (decrease in pH), CO2, temperature, and 2,3-BPG all occur in active skeletal muscle. They also all encourage O2 release from hemoglobin.  This makes sense if you think that working muscle is metabolic tissue and needs oxygen to survive.  Incorporating the larger concept will also allow you to predict the flow of reactions in other situations throughout the body. 

Study Skill #6 - Stare at the graphs and plots.  These questions are virtually freebies on exams because all the information you need to solve them is included.  Know what the x- and y-intercept, the slope, and the area under the graph represent.  Know what makes the graphed line move to the right or left.  You will absolutely be asked about the Michaelis-Menten graph and the Hemoglobin dissociation curve - these are staples of biochemistry.

Study Skill #7 - Seek to understand first, and then memorize.  Like many other courses, biochemistry can be overwhelming at first.  There is no easy way to memorize every amino acid or metabolic reaction.  But students always claim that if they take the time to first get the concept down, the memorizing is not as difficult as it once seemed.  Stay focused, break it down into small steps, and practice.





(Source: www.medstudysites.com)

Saturday, June 22, 2013

Human Genome Project: Human Genome and Human Gene Therapy

The Human Genome and Human Gene Therapy:

The strategy of human gene therapy is the introduction of DNA into human cells to correct inherited genetic deficiencies.

E.g. Severe Combined Immune Deficiency (SCID). One form of SCID results from genetically inherited defects in gene encoding adenosine Deaminase (ADA), an enzyme involved in nucleotide biosynthesis. Another form of SCID arises from defect in cell surface receptor for Interleukin which triggers differentiation. In both case the progenitor stem cells cannot differentiate into mature immune cells like T and B lymphocytes. Children with this disorder are highly susceptible to bacterial and viral infections.


A gene therapy trial initiated in 1999 was successful in correcting a form of SCID caused by defective cytokine receptors. The researchers introduced the corrected gene for γc cytokine receptor subunit in retrovirus and this was again transfected into CD34+ cells (the stem cells that give rise to immune system cells). The transformed cells were placed back into  the patient’s bone marrow. The corrected gene conferred a growth over untreated cells. A functioning immune system was detected. Although two of patients developed severe form of leukemia due to retrovirus itself got integrated itself into a chromosome of stem cells resulting in abnormally high expression of hematopoietic oncogene that led to uncontrolled cell growth.

The first human gene therapy trial was carried out at National Institute of Health in Bethesda, Maryland in 1990. The patient was a four year old girl crippled by ADA deficiency. Bone marrow cells from the child were transformed with an engineered retrovirus containing a functional, ADA gene. The transformed cells in vivo were introduced into the patient’s marrow. Four years later, the child was leading a normal life.

Although the  gene  therapy is absolute  care it is associated with various risks. One major impediment proved to be the inefficiency of introducing new genes into cells. Transformation failed in many cells, and the number of transformed cells often proved insufficient to reverse the disorder.

Human gene therapy is not limited to genetic diseases. Cancer cells are being targeted by delivering genes for proteins that might destroy the cell or restore the normal cell division. Immune system cells associated with tumors can be genetically modified to produce tumor necrosis factor (TNF). When these lymphocytes are taken from a cancer patient, modified, and reintroduced, the engineered cells target the tumor, and the TNF they produce causes tumor shrinkage. AIDS may also be treatable with gene therapy; DNA that encodes an RNA molecule complementary to a viral HIV mRNA could be introduced into immune system cells (the targets of HIV). The RNA transcribed from the introduced DNA would pair with the HIV mRNA, preventing its translation and interfering with the virus's life cycle.

Human Genome Project:

Discussion in mid 1980 led to initiation of the Human Genome Project in 1989 but the actual work of sequencing began at 1990. Researchers team first generated a detailed physical map of human genome with clones derived from each chromosome.
Fig: The Human genome project strategy: Sequenced by shotgun sequencing.
Human genome project was completed in 2001 and published in April 2003. We have only 25, 000 – 30, 000 genes and 3.9 X 109 bp per haploid genome i.e. 23 chromosomes. 1.1 to 1.4% of our DNA actually encodes proteins. More than 50% of our genome consist of short repeated sequences the vast majority of which about 45% come from transposons. The human genome

can encode 30,000 to 40,000 proteins. There are more than 3 million SNPs. Whole genome contains 10% of Alu elements and present in GC rich region. This project was handled by international collaboration involving groups from the USA, UK, Japan, France, Germany and china known as International Human Genome Sequencing Consortium (IHGSC).

The human and chimpanzee genome differ by only 1.2% at the level of base pairs and even less in gene encoding proteins. This creates 35 million base pair changes.

The overall approach, referred to as hierarchical shotgun sequencing, consisted of fragmenting the entire genome into pieces of approximately 100–200 kb and inserting them into bacterial artificial chromosomes (BACs). The BACs were then positioned on individual chromosomes by looking for marker sequences known as sequence-tagged sites STSs), whose locations had been already determined. STSs are short (usually < 500 bp), unique genomic loci for which a PCR assay is available. Clones of the BACs were then broken into small fragments (shotgunning). Each fragment was then sequenced,  and computer algorithms were used that recognized matching sequence information from overlapping fragments to piece together the complete sequence.

On the basis of STS, PCR based sequencing was done using primers that recognize the vector terminal sequence and using labeled dNTPs. ddNTP was used to terminate the chain elongation process to generate short fragments formed due to addition of ddNTP in the complementary site. These fragments were then sequences and assembled to determine the overlapping bases on the basis of these overlap fragments from entire genome fragments were joined to produce final sequence.

For More information on Human Genome Project, Visit:

(Source: Lehninger's Textbook of Biochemistry)

Transgenic Animals and DNA Micro-array

Transgenic animals:
The strategy here is injection of genes in fertilized mouse ovum, these genes will be incorporated into the genome and found in both somatic and germ cells. By this strategy many transgenic animals have been established and are studied for tissue specific effect on gene expression and effects of overproduction of gene products. The transgenic approach has been used to correct a genetic deficiency in mice. Fertilized ova obtained from mice with genetic hypogonadism were injected with DNA containing the coding sequence for the gonadotropin- releasing hormone (GnRH) precursor protein. This gene was expressed and regulated normally in the hypothalamus of certain number of mice, and these animals were in all respects normal.

Application of Restriction Fragment Length Polymorphism (RFLP)




DNA-based screening is useful not only in determining if an unborn fetus is affected, but also in detecting carriers of the mutated gene. PKU, like many inborn errors of amino acid metabolism, is inherited as an autosomal recessive trait. Identification of heterozygotes can aid in future family planning.

Another approach of detecting the βs globin mutation is by the use of Allele specific oligonucleotide probe (ASO). If PCR is carried out using such primer then it is called ASO-PCR.

Application of DNA Fingerprinting in molecular analysis of Disease: Hemoglobinopathies

Normal Gene variation:

There is normal variation in DNA sequences, this polymorphism occur approximately once in every 500-1000 nucleotides. There are 3, 300, 000 single nucleotide polymorphisms (SNPs) relative to standard initially sequenced human reference genome. Over 80% of SNPs found in DNA have already been found. Each human differs from the next by about 1 bp in every 1, 000 bp and this is what (snips) makes each individual different. There are genomic deletions and insertions of DNA (ie, copy number variations; CNV) as well as single-base substitutions. These are usually occurring in non coding region of DNA. This heritable polymorphism of DNA structure can be associated with certain diseases.

DNA Fingerprinting

DNA Fingerprinting also called DNA typing or DNA profiling:

DNA fingerprinting is based on sequence polymorphisms, slight sequence differences between individuals, 1 bp in every 1,000 bp, on average. Every individual has some differences. Some of the sequence change affects recognition sites for restriction enzymes, resulting in variation in the size of DNA fragments produced by digestion with a particular restriction enzyme. These variations are restriction fragment length polymorphisms (RFLPs).

Another type of sequence variation, and the one now most commonly in DNA typing involves short tandem repeats (STRs). The detection of RFLPs relies on Southern blotting.

Friday, June 21, 2013

Polymerase Chain reaction

It is a test tube method for rapid DNA amplification. It uses two primers that can attach to 3’ end of each strand by complementary base pairing. Primers are 20-35 nucleotides long.

The basic steps in PCR are:

  1. Denaturation of target DNA to separate two strands by heating at 900C.
  2. Cooling of denatured DNA to 40 – 600C this provides annealing of primers.
  3. Annealing of Primer to flanking 3’ end of both single stranded DNA. First temperature is increased to 2-30C above the Tm which gives greater specificity of binding of primer to complementary site and later it is decreased to 2-30C  below Tm permits  efficient amplification. This is the principle of Touchdown PCR.
  4. Extension of primer in 5’ to 3’ direction by DNA polymerase (dNTPs are added to 3’-OH of primer) in both strands. Carried at 720C.
  5. Denaturation of copied new DNA, and allowed to cyclize from step 1 though 3 to get million of copies of target DNA.

Sequencing of DNA

After cloning and amplification of DNA it can be analyzed for its sequence determination. The manual enzymatic method (sanger) can be used where ddNTS are used which can terminate DNA strand synthesis at specific nucleotides as the strand is synthesized on purified template nucleic acid. Here radiolabelled primers are used. One can separate fragments according to size using PAGE. Another method is of Maxam and Gilbert, employs chemical method to cleave the DNA molecules where they contain the specific nucleotides.



Automated DNA sequencing is another approach. Here four different fluorescent labels – one representing each nucleotide are used. Each emits a specific signal upon excitation by laser beam of particular wavelength, which can be recorded by computer. This is the most widely used method.

(Source: Harper's Illustrated Biochemistry)

Thursday, June 20, 2013

Blotting techniques

Visualization of specific DNA, RNA or Protein out of contaminants can be done by blotting techniques like those shown in figure above. These procedure help to determine the number of copies of genes present in the given tissue or whether there are any gross alteration in a gene (deletions, insertions, or rearrangements) because any alteration will change the size which can be resolved by electrophoresis.

Hybridization uses to identify a clone with a particular DNA Segment

Use of hybridization to identify a clone with a particular DNA segment:

Library and Screening of Library.

A collection of different recombinant clones is called library.

Genomic library:

Due to availability of restriction enzymes and cloning vectors the entire genome of organism can be individually packed into a vector. A genomic library is a collection of fragments of total ds-DNA (as obtained by cutting with restriction endonuclease) of a cell line or tissue.

Screening recombinants for inserted DNA fragments

Fig. Plasmid pBR322
Using the plasmid pBR322, a piece of DNA is inserted into PstI site. This insertion disrupts the gene conferring ampicillin resistance to the host bacterium. Hence, the chimeric plasmid will no longer survive when plated on a substrate medium that contains this antibiotic but survives if this is not present. This differential sensitivity to tetracycline and ampicillin can therefore be used to know that the success of recombination. A similar scheme can be used for the identification of DNA insert that can produce peptide which complements the function of deleted form of beta galactosidase gene from vector (DNA insert disrupt the function of this gene). If the insert is successful, it will produce this enzyme which will hydrolyze dye producing blue colonies.

Vectors for cloning

Cloning vectors:

A vector is a molecule of DNA where DNA of interest can be integrated. Essential properties of a vector include: 1) It must be capable of autonomous replication within a host cell; 2) it must contain at least one restriction endonuclease site; 3) it must carry at least one gene that can be used to select the cloned vector, such as an antibiotic resistance gene (selectable markers) Bacterial Plasmids:

Uses of Recombinant DNA Technology

  1. Understanding      molecular      basis      of      disease      like      thalassemia,       familial hypercholesterolemia, cancer, diabetes, etc.
  2. Production of human proteins for therapy e.g. insulin, tissue plasminogen activator, etc.
  3. Production of protein for vaccines e.g. hepatitis B and diagnostic testing e.g. AIDS test.
  4. Predict the risk of disease and monitor pharmacological effects
  5. Use In forensic medicine.
  6. Gene therapy e.g. ADA deficiency, sickle cell disease, etc.
  7. Isolation and manipulation of DNA, including end to end joining of sequence from different sources to make chimeric molecule is the essence of recombinant DNA technology. This involves several techniques and reagents.

Thursday, June 13, 2013

13 food stuffs which keeps you slim and healthy

Fig. Protein Diet
1. Protein
I’m fond of this macronutrient powerhouse for so many reasons: It promotes healthy skin, hair, nails, bones, and muscle. It’s also a fabulous weight-loss aid, according to a 2005 study from Arizona State University. Protein increased satiety (satisfaction and feelings of fullness) and increased after-meal calorie burn. In other words, eating protein-rich meals, rather than higher-carbohydrate ones, leads to more satisfaction, less hunger, and more fat burn. I love that: three benefits in one. Earlier research also found that people following higher-protein diets generally decrease their food intake by an average of 10 percent (about 200 calories).

Health is Wealth: 50 tips to loose weight and stay healthy

If you’re trying to drop a few pounds, don’t start off by trying to overhaul all your eating and exercise habits. You’re better off finding several simple things you can do on a daily basis—along with following the cardinal rules of eating more vegetables and less fat and getting more physical activity. 

1. Indulge in fat releasing foods. They should help keep you from feeling deprived and bringing on higher-calorie foods. For instance:
  • Honey. Just 64 fat releasing calories in one tablespoon. Drizzle on fresh fruit.
  • Eggs. Just 70 calories in one hard-boiled egg, loaded with fat releasing protein. Sprinkle with chives for an even more elegant treat.
  • Part-skim ricotta cheese. Just 39 calories in one ounce of this food, packed with fat releasing calcium. Dollop over a bowl of fresh fruit for dessert.
  • Dark chocolate. About 168 calories in a one-ounce square, but it’s packed with fat releasing fiber.
  • Shrimp. Just 60 calories in 12 large.
  • MORE: 13 fat releasing foods »

Sunday, June 9, 2013

Relation between HbA1c and Estimated Average Glucose (eAG)


Why is relating HbA1c to glucose important?

We are frequently asked about the relationship between HbA1c and plasma glucose levels. Many patients with diabetes mellitus now perform self-monitoring of blood glucose (SMBG) in the home setting, and understanding the relationship between HbA1c and glucose can be useful in setting goals for day-to-day testing.

Thursday, June 6, 2013

Hormones and Body Weight

Excessive intake of calories in relation to energy expenditure over a long period of time results in body weight gain.

A complex physiologic system regulates energy homeostasis by integrating signals from peripheral organs with central coordination in the brain. The hypothalamus functions as the main cerebral center in which these signals converge.

Wednesday, May 22, 2013

HORMONES REGULATING MINERAL METABOLISM

REGULATION OF MINERAL METABOLISM:

PTH and 1, 25-dihydroxyvitamin D are the primary hormones regulating bone and mineral metabolism. Physiological role of calcitonin has not yet been established. PTHrP is the principal mediator of humoral hypercalcemia of malignancy.

PARATHYROID HORMONE

PTH (chromosome 11) is synthesized and secreted by parathyroid glands located posterior to thyroid gland. The glands consist of chief and oxyphil cells; the chief cells synthesize, store, and secrete PTH. It is cleared by liver and kidney. PTH acts directly on bone and kidney, and indirectly on intestine to regulate concentration of calcium and phosphate in plasma.

Phosphate: Introduction, Clinical significance and measurement


An adult contains 600 g of phosphorus in inorganic and organic phosphates, of which about 85% is in skeleton and rest in soft tissue and extracellular fluid. Though plasma has both organic and inorganic phosphate but inorganic phosphate (H2PO4- and HPO42-) is measured. Approximately 10% is protein bound and 35% complexed with sodium, calcium, magnesium; and remainder 55% is free. The organic phosphates are located within the cell of blood.

Inorganic phosphate is a major component of hydroxyapatite in bone and is the source of intracellular and extracellular pool. Organic phosphate in cells is found to be incorporated into nucleic acid, phospholipids, phosphoproteins and ATP, GTP, Creatine phosphate, etc. Phosphate is important for activity of adenylate cyclase, 25-hydroxy vitamin D-1α-hydroxylase and those involved in 2, 3-diphosphoglycerate.

Calcium : Introduction, clinical significance and measurement

About 99% of calcium occurs in bone, along with calcium 85% of phosphate and 55% magnesium. The concentration of these minerals depends on net effect of bone mineralization, intestinal absorption and renal excretion. PTH and 1, 25-dihydroxyvitamin D are the principle hormones regulating these three processes.

Thursday, April 11, 2013

Urine Sodium and Fractional excretion of Sodium (FENa)

Urine Sodium and FENa:

Urine sodium is the concentration of sodium in the urine. Remember that the normal value for blood sodium is 135-145 mmol/litre. Note that the range of sodium in urine is far greater than the range in the blood.

The reference range varies according to age and sex. If also depends upon the hydration state of the person. 

  40-220 mmol/L (For male)
27-287 mmol/L (For female)

For children aged 6-10 Year:
41-115 (For male)
20-69 (For female)

Wednesday, April 10, 2013

Human Influenza A (H7N9) virus in China: new update


Human infection with influenza A (H7N9) virus in China - update

 As of 9 April 2013 (14:00 CET), the National Health and Family Planning Commission notified WHO of an additional three laboratory-confirmed cases of human infection with influenza A(H7N9) virus.
The latest laboratory-confirmed cases include two patients from Jiangsu – an 85 -year-old man who became ill on 28 March 2013 and a 25-year-old pregnant woman who became ill on 30 March 2013. Both are in severe condition. The third patient is a 64-year-old man from Shanghai who became ill on 1 April 2013, and died on 7 April 2013.
To date, a total of 24 cases have been laboratory confirmed with influenza A(H7N9) virus in China, including seven deaths, 14 severe cases and three mild cases.
More than 600 close contacts of the confirmed cases are being closely monitored. In Jiangsu, investigation is ongoing into a contact of an earlier confirmed case who developed symptoms of illness.
The Chinese government is actively investigating this event and has heightened disease surveillance. Retrospective testing of recently reported cases with severe respiratory infection may uncover additional cases that were previously unrecognized. An inter-government task force has been formally established, with the National Health and Family Planning Commission leading the coordination along with the Ministry of Agriculture and other key ministries. The animal health sector has intensified investigations into the possible sources and reservoirs of the virus.
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