Biomedical Laboratory Science

Friday, March 23, 2018

Genetics of Coronary Artery Disease: Discovery, Biology and Clinical Translation !

Coronary artery disease is the leading global cause of mortality. Long recognized to be heritable, recent advances have started to unravel the genetic architecture of the disease. Common variant association studies have linked approximately 60 genetic loci to coronary risk. Large-scale gene sequencing efforts and functional studies have facilitated a better understanding of causal risk factors, elucidated underlying biology and informed the development of new therapeutics. Moving forwards, genetic testing could enable precision medicine approaches by identifying subgroups of patients at increased risk of coronary artery disease or those with a specific driving pathophysiology in whom a therapeutic or preventive approach would be most useful.

  • Coronary artery disease is a heritable disorder that remains the leading cause of global mortality despite advances in treatment and prevention strategies. Human genetics studies have started to unravel the genetic underpinnings of this disorder.
  • Gene discovery efforts have rapidly transitioned from family-based studies (for example, those that led to the discovery of familial hypercholesterolaemia) to large cohorts that facilitate both common and rare variant association studies.
  • Common variant association studies have confirmed ∼60 genetic loci with a robust association with coronary disease, the majority of which are of modest effect size and in non-coding regions. Rare variant association studies have linked inactivating mutations in at least nine genes with risk of coronary artery disease.
  • Human genetics and large-scale biobanks can facilitate drug development for coronary artery disease by highlighting causal biology and helping to understand the phenotypic consequences of lifelong deficiency of a given protein.
  • Genomic medicine may provide patients and their health care providers with genetic data that will aid in coronary artery disease prevention and treatment.
  • Genome editing to introduce mutations that are protective against coronary artery disease into the population could prove curative with a one-time injection, although substantial additional work is needed to confirm efficacy and safety, and to address the underlying ethics.
Observational epidemiology and translational research efforts have led to significant progress in improving the understanding of the pathophysiology underlying coronary artery disease (CAD). Prevention and treatment strategies developed on the basis of this knowledge led to a >50% decrease in age-adjusted CAD mortality rate in the United States between 1980 and 2000. However, despite these advances, CAD remains the leading global cause of mortality. Current predictions estimate that more than 900,000 individuals in the United States will suffer a myocardial infarction (heart attack) or die of CAD this year.

This review outlines research efforts to understand the genetic drivers of CAD, the role of human genetics in catalysing CAD drug discovery efforts and the promises and challenges of integrating genetic information into routine clinical practice.

Saturday, March 17, 2018

Strategies for Preventing Amplicon Contamination in Molecular Laboratory !

The high sensitivity of the polymerase chain reaction (PCR)—theoretically with lower limits of detection as little as a single template molecule; practically, 10 to 100 copies for many assays as run—is one of its greatest strengths, but also its greatest weakness. As the method works through creating copies of its target, any positive sample can lead to large numbers of molecules which can in turn contaminate subsequent reactions and cause false positive results.

To get a sense of the scope of this, consider a successful “average” 25μl PCR somehow getting opened and spilled in the lab. This would contain on the order of 10^12 template copies (amplicons); in other words, if a thorough cleaning reduced this by a million fold, you’d still have a million amplicon copies “floating around,” each of which could contaminate a reaction. If you’re fortunate enough to have never experienced this first-hand, you can thank the widespread acceptance of real-time PCR methods, which do away with having to open reaction tubes post amplification, and perhaps gain an appreciation of why anyone who has been through the experience treats the risk as real and ever-present.

Tuesday, February 13, 2018

Some Breast Cancers Fail to Respond to Treatments, Why?

Most breast cancers are estrogen receptor-positive, meaning that signals received from estrogen, a hormone, promote the growth of the tumors. To stop these cancers from spreading, estrogen inhibitors are usually prescribed. But what happens when tumors develop treatment resistance?

Studies suggest that "approximately 70 percent" of all the breast cancers are estrogen receptor-positive (ER-positive).

These types of cancer are typically treated with drugs — such as tamoxifen and fulvestrant — that either lower the levels of the hormone or inhibit the estrogen receptors to prevent the tumors from spreading. This is known as endocrine therapy.

However, around a third of the people treated with these drugs develop resistance to them, which negatively impacts their chances of survival. The mechanisms that underlie the tumors' resistance to therapy is not well understood and currently poses a major challenge.

Saturday, February 10, 2018

VITAMINS: The Micronutrients in Our Body !

The essential macronutrients are water, proteins, carbohydrates, fats, vitamins, and minerals.

In developed countries, vitamin deficiencies result mainly from poverty, food fads, drugs, or alcoholism. Vitamin toxicity (hypervitaminosis) usually results from taking megadoses of Vitamin A, D, B6, or niacin. In general, excess amounts of water-soluble vitamins are excreted via the Kidneys.

Vitamins may be Fat soluble (vitamins A, D, E, and K) or Water soluble (B vitamins and vitamin C). The B vitamins include biotin, Folate, niacin, pantothenic acid, riboflavin, thiamine, pyridoxine, and B12. After digestion and absorption, which circulatory system carries fat and fat-soluble vitamins?
“Vitamins are the essential nutrients that our body needs in small amounts. More specifically, an organic compound is defined as a vitamin when an organism requires it, but not synthesized by that organism in the required amounts (or at all). There are thirteen recognized vitamins.”
Vegans may develop vitamin B12 deficiency unless they consume yeast extracts or Asian style fermented foods. Strictly, vegetarian diets also tend to be low in calcium, iron, and zinc.

Saturday, January 27, 2018

Study Sheds Light on How High Cholesterol Causes Cancer !

New research from the University of California, Los Angeles has found a previously unknown molecular mechanism involving cholesterol that may promote tumor growth in the intestines.

A report on the study — published in the journal Cell Stem Cell — reveals how increasing levels of cholesterol in mice increased proliferation of intestinal stem cells and made tumors grow faster.

One of the methods that the researchers used to increase the availability of cholesterol to intestinal cells in the mice was to feed them a high-cholesterol diet.

"We were excited to find," says senior author Peter Tontonoz, a professor of pathology and laboratory medicine, "that cholesterol influences the growth of stem cells in the intestines, which in turn accelerates the rate of tumor formation by more than 100-fold."

He and his colleagues believe that their findings could pave the way to new treatments for gastrointestinal diseases, such as colon cancer.

Thursday, January 25, 2018

Do Human Pheromones Exist? Are They The Real Deal?

Despite the prevalence of pheromone products on the market, substantial evidence that they can induce sexual attraction is lacking.

Search for “pheromones products” on the internet, and dozens of sprays and perfume additives will appear—many claiming to be able to increase your attractiveness to the opposite sex. Some companies, such as the Athena Institute, which, according to its founder, Winnifred Cutler, published its 108th consecutive ad in The Atlantic this month, assert that scientific studies back up their claims.

While there have been several experiments examining the effects of compounds extracted from people’s armpits, much of the data on sex-related behaviors, The Scientist has found, go back more than a decade and were met then—and still now—with skepticism from pheromone researchers. “I am not compelled by any studies that are out there that say there is an active steroid component from the underarm that causes [sexual attraction],” says George Preti, an organic chemist at the Monell Chemical Senses Center in Philadelphia who conducted some of the early human pheromone trials.

Tuesday, January 23, 2018

Cutaneous Leishmaniasis: Immune Responses in Protection and Pathogenesis.

Cutaneous leishmaniasis is a major public health problem and causes a range of diseases from self-healing infections to chronic disfiguring disease. Currently, there is no vaccine for leishmaniasis, and drug therapy is often ineffective. Since the discovery of CD4+ T helper 1 (TH1) cells and TH2 cells 30 years ago, studies of cutaneous leishmaniasis in mice have answered basic immunological questions concerning the development and maintenance of CD4+ T cell subsets. However, new strategies for controlling the human disease have not been forthcoming. Nevertheless, advances in our knowledge of the cells that participate in protection against Leishmania infection and the cells that mediate increased pathology have highlighted new approaches for vaccine development and immunotherapy. In this Review, we discuss the early events associated with infection, the CD4+ T cells that mediate protective immunity and the pathological role that CD8+ T cells can have in cutaneous leishmaniasis.

Cutaneous leishmaniasis — which is caused by several protozoal parasites of the genus Leishmania — is endemic to South and Central America, Northern Africa, the Middle East and parts of Asia, and an estimated 1 million new cases arise each year. Of particular interest to immunologists is the wide range of clinical manifestations associated with this disease, which, similar to tuberculosis and leprosy, is dictated largely by the type and magnitude of the immune response of the host. As in most infections, the immune response to cutaneous leishmaniasis depends on many host factors, as well as on the differences between the infecting Leishmania spp. Experimental infections in mice also exhibit a spectrum of clinical presentations depending on the mouse strain and the infecting parasite species or strain used.
  • Cutaneous leishmaniasis exhibits a wide spectrum of clinical presentations that is determined largely by the host immune response. The host immune response to infection is influenced both by host genetics and the Leishmania spp. and/or strain.
  • The rapid recruitment of neutrophils and inflammatory monocytes following infection with Leishmania influences the course of disease. Neutrophils can have both protective and deleterious roles, whereas inflammatory monocytes kill Leishmania parasites and differentiate into monocyte-derived dendritic cells that promote the development of protective CD4+ T helper 1 (TH1) cells.
  • Control of Leishmania infection depends on the production of interferon-γ by CD4+ TH1 cells, which leads to enhanced killing by macrophages due to the production of reactive oxygen species and nitric oxide.
  • CD8+ T cells recruited to Leishmania lesions exhibit a cytolytic profile and lyse infected cells without killing the parasites, which leads to enhanced inflammation and increased severity of disease. Controlling these pathogenic CD8+ T cells, or the downstream mediators of inflammation that they induce, is a new approach to leishmaniasis immunotherapy.
  • Infection with Leishmania generates several types of CD4+ T cells that mediate resistance to reinfection, including effector T cells, effector memory T cells, central memory T cells and tissue-resident memory T cells. There is currently no Leishmania vaccine, and a hurdle for vaccine development is that the most effective T cells are short-lived effector T cells; targeting longer lived central memory and tissue-resident memory T cells is an alternative approach.

Monday, January 22, 2018

Kaplan MCAT Biology Review - Test Prep !

MCAT Biology Review,

Test Prep for the MCAT Exam


The MCAT is changing in 2015. With the addition of three semesters’ worth of material, more advanced critical thinking skills, a longer duration, and changes in Biology content, the new exam requires even more diligent prep with resources from Kaplan Test Prep.

Kaplan's MCAT Biology Review offers:

Sunday, January 14, 2018

Cancer Transcriptome Profiling at the Juncture of Clinical Translation !

Methodological breakthroughs over the past four decades have repeatedly revolutionized transcriptome profiling. Using RNA sequencing (RNA-seq), it has now become possible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples. These transcriptomes provide a link between cellular phenotypes and their molecular underpinnings, such as mutations. In the context of cancer, this link represents an opportunity to dissect the complexity and heterogeneity of tumours and to discover new biomarkers or therapeutic strategies. Here, we review the rationale, methodology and translational impact of transcriptome profiling in cancer.

Transcriptomics is the large-scale study of RNA molecules by use of high-throughput techniques. It examines the abundance and makeup of a cell's transcriptome. In contrast to DNA, which is largely identical across all cells of an organism, the actively transcribed RNA is highly dynamic, reflecting the diversity of cell types, cellular states and regulatory mechanisms. Because a transcriptome profile can be regarded as a signature or snapshot of the underlying cell state, the experimental profiling of samples and specimens can provide insights into their unique biology.

Depending on the specific approach, transcriptomics can not only reveal the architecture of gene expression but also provide details on the structure, modification and variation of individual transcripts. Advances in transcriptome profiling, specifically the development of genome-wide methodologies targeting diverse RNA species, have enabled us to discover the seemingly endless complexity of RNA biology and to comprehensively annotate the human genome and other eukaryotic genomes. Arguably, transcriptomics is currently the most well-established modality and foundation of functional genomics, a field of study for which the goal is to synthesize large-scale data to understand the mechanisms that govern cellular and organismal phenotypes.
  • RNA sequencing (RNA-seq) has the potential to bridge tumour genotypes (for example, mutations) and their phenotypic consequences (for example, cancer molecular subtypes).
  • The field of transcriptomics has matured thanks to lockstep developments in experimental protocols, algorithms and databases.
  • Methodological and algorithmic advances continue to enable clinical applications of transcriptome profiling.
  • Detection of gene fusions is the most immediate application of RNA-seq.
  • Gene expression signatures have demonstrated prognostic and predictive value.
  • Transcriptome profiling will be essential for immuno-oncology.

Thursday, December 7, 2017

MCQ 12. 11 years old boy, restless all time, unable to concentrate in class, hardly ever in his seat, roams around the hall, difficulty in playing quietly.

MCQ 12. An 11 years old boy is all the time so restless that the rest of the class is unable to concentrate. He is hardly ever in his seat and roams around the hall. He has difficulty in playing quietly.

What is the the most likely diagnosis?
a. Attention-deficit hyperactivity disorder 
b. Conduct disorder 
c. Depressive disorder 
d. Schizophrenia

Correct answer: Click here

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