iPSCs are pluripotent; unlike ESC, iPSCs are not derived from the embryo, but instead created from differentiated cells in the lab through a process – cellular reprogramming.
A knockout mouse is a mouse in which a specific gene has been inactivated or“knocked out” by replacing it or disrupting it with an artificial piece of DNA.
The loss of gene activity often causes changes in a mouse's phenotype and thus provides valuable information on the function of the gene.
iPSCs are pluripotent; unlike ESC, iPSCs are not derived from the embryo, but instead created from differentiated cells in the lab through a process – cellular reprogramming.
A knockout mouse is a mouse in which a specific gene has been inactivated or“knocked out” by replacing it or disrupting it with an artificial piece of DNA.
The loss of gene activity often causes changes in a mouse's phenotype and thus provides valuable information on the function of the gene.
Introduction.
Properties of Stem Cells.
Key Research events.
Embryonic Stem Cell.
Stem cell Cultivation.
Stem cells are central to three processes in an organism.
Research & Clinical Application of stem cell.
Research patents.
Conclusion.
Reference.
Imagine that you have been told you have an illness that cannot be cured or what if your body has been irreversibly paralysed. There is no hope. But there is a science that could change that. It’s Called Stem Cell Research and it’s an important step in the medical revolution. But it comes with controversies as it uses Human Embryos’ as Raw Material.
But something astounding happened in the year 2006 that removed the usage of surplus embryos from the equation altogether. It’s about a brand new technology that can turn back the clock on your body cells. This is cutting edge of science where new developments are happing all the time. The iPSCs could be the potential medicine of 21st century. So what are stem cells? Why do they Matter? What are iPSCs and how it changed the biological rules?
INTRODUCTION
ROLE IN CELL LINE CHARACTERIZATION
CAUSES OF TRANSFORMATION
METHODS OF TRANSFECTION
CHARACTERISTICS OF TRAANSFORMED CELLS
GENETIC INSTABILITY
IMMORTALIZATION
ABRERANT GROWTH CONTROL
TUMORIGENECITY
CHROMOSOMAL ABERATION
APPLICATION
CONCLUSION
REFERENCE
Deciphering DNA sequences is essential for virtually all branches of biological research. With the
advent of capillary electrophoresis (CE)-based Sanger sequencing, scientists gained the ability to
elucidate genetic information from any given biological system. This technology has become widely
adopted in laboratories around the world, yet has always been hampered by inherent limitations in
throughput, scalability, speed, and resolution that often preclude scientists from obtaining the essential
information they need for their course of study. To overcome these barriers, an entirely new technology
was required—Next-Generation Sequencing (NGS), a fundamentally different approach to sequencing
that triggered numerous ground-breaking discoveries and ignited a revolution in genomic science.
A real-time polymerase chain reaction is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, i.e. in real-time, and not at its end, as in conventional PCR.
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Introduction.
Properties of Stem Cells.
Key Research events.
Embryonic Stem Cell.
Stem cell Cultivation.
Stem cells are central to three processes in an organism.
Research & Clinical Application of stem cell.
Research patents.
Conclusion.
Reference.
Imagine that you have been told you have an illness that cannot be cured or what if your body has been irreversibly paralysed. There is no hope. But there is a science that could change that. It’s Called Stem Cell Research and it’s an important step in the medical revolution. But it comes with controversies as it uses Human Embryos’ as Raw Material.
But something astounding happened in the year 2006 that removed the usage of surplus embryos from the equation altogether. It’s about a brand new technology that can turn back the clock on your body cells. This is cutting edge of science where new developments are happing all the time. The iPSCs could be the potential medicine of 21st century. So what are stem cells? Why do they Matter? What are iPSCs and how it changed the biological rules?
INTRODUCTION
ROLE IN CELL LINE CHARACTERIZATION
CAUSES OF TRANSFORMATION
METHODS OF TRANSFECTION
CHARACTERISTICS OF TRAANSFORMED CELLS
GENETIC INSTABILITY
IMMORTALIZATION
ABRERANT GROWTH CONTROL
TUMORIGENECITY
CHROMOSOMAL ABERATION
APPLICATION
CONCLUSION
REFERENCE
Deciphering DNA sequences is essential for virtually all branches of biological research. With the
advent of capillary electrophoresis (CE)-based Sanger sequencing, scientists gained the ability to
elucidate genetic information from any given biological system. This technology has become widely
adopted in laboratories around the world, yet has always been hampered by inherent limitations in
throughput, scalability, speed, and resolution that often preclude scientists from obtaining the essential
information they need for their course of study. To overcome these barriers, an entirely new technology
was required—Next-Generation Sequencing (NGS), a fundamentally different approach to sequencing
that triggered numerous ground-breaking discoveries and ignited a revolution in genomic science.
A real-time polymerase chain reaction is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR, i.e. in real-time, and not at its end, as in conventional PCR.
https://www.patreon.com/biotechlive
SUPPORT EDUCATION... SUPPORT US
Towards Precision Medicine: Tute Genomics, a cloud-based application for anal...Reid Robison
Tute Genomics is cloud-based software that can rapidly analyze entire human genomes. The cost of whole genome sequencing is dropping rapidly and we are in the middle of a genomic revolution. Tute is opening a new door for personalized medicine by helping researchers & healthcare organizations analyze human genomes.
A DNA microarray (also commonly known as DNA chip or biochip) is a collection of microscopic DNA spots attached to a solid surface.
The core principle behind microarrays is hybridization between two DNA strands, the property of complementary nucleic acid sequences to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs.
Clinical molecular diagnostics for drug guidanceNikesh Shah
1. Be familiar with next generation molecular diagnostic techniques that can provide guidance in clinical decision making
2. Identify the utility of these diagnostic approaches with some examples
3. Be aware of the challenges that exist in implementing these tools as part of the routine clinical decision making process, especially in resource limited settings
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
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3. Approaches for Characterizing Differential Gene
Expression
Low-throughput or Single Gene Methods
High-throughput or Large-Scale Methods
4. The Hybridization of Complementary
Strands of DNA/RNA
Is the Underlying Principle of All
Methods of Differential Gene Expression.
5. Single Gene Methods
Northern Blotting, cumbersome, time-consuming
Nuclease protection, at least 10 fold more sensitive
Quantitative RT-PCR, state of the art
6. High-throughput Methods
Serial Analysis of Gene Expression (SAGE)
Rapid Analysis of Gene Expression (RAGE)
Representational Difference Analysis (RDA)
Suppression Subtractive Hybridization (SSH)
Differential screening (plus/minus screening)
Differential Display (DD)
DNA Microarray
Comprehensive evaluation
400,000 Northern Blotting
7. What is DNA Microarray?
A large number of genes deposited onto a glass slide (large scale dot blot)
The RNA sample is RT with simultaneous incorporation of label,
resulting in labeled cDNA.
Microarray slides serve as hybridization targets for labeled cDNA
Reverse Northern blotting
Patrick O Brown
Mark Schena
8. Basic Steps in Performing a DNA Microarray Experiments
1- Processing cDNA clones to generate print-ready material
2-Printing cDNA clones (or oligonucleotide) onto a substrate
3-Sample RNA isolation
4-Preparation of the probe (e.g. cDNA synthesis and labeling, RT reaction)
5- Hybridization of labeled probe DNA to the DNA arrayed on the substrate
6-Image acquisition, image analysis and data analysis
9.
10. Microarray Fabrication Technologies
In Situ Synthesis of Nucleic Acid (Chip ,GeneChip,oligonucleotide array)
15-20 different 25-mer oligonucleotides
Exogenous Deposition of cDNA (cDNA, spotted array)
Single DNA fragments, greater 0.5 Kb
11.
12. Common Approaches for Microarray Fabrication
2-Contact printing (Patrick O Brown,Stanford University)
3- Non-Contact Printing (Pin and Ring, Bubble Jet, Ink Jet)
1- Photolithography (Affymetrix, Oligonucleotide Microarray)
13. What to spot?
As many known genes as possible
Genes that are most relevant
A combination of both approaches
Publicity available clones (IMAGE)
In_house derived (SSH)
Custom made/purchased libraries
14. Analysis of Gene Expression
Monitoring Changes in Genomic
DNA
Gene Discovery, Sequencing and Pathway Analysis
When to use Microarray
15. Analysis of Gene Expression
1- Different tissues or different developmental states
2- Normal or diseased states
3- Exposure to drugs or different physiological conditions
16. Monitoring Changes in Genomic DNA
Hybridization to oligonucleotide is sensitive in
detection of single-nucleotide mismatches
Single Nucleotide Polymorphisms (SNPs)
High Density Oligonucleotide Array
Cancer cells typically exhibit genomic instability
17. Detailed Protocols
Stanford University
Albert Einstein College of Medicine
NHGRI
Cold Spring Harbor Laboratory
Collection of Protocols
TIGR Protocols
www.cmgm.stanford.edu/pbrown/
www.sequence.aecom.yu.edu/bioinf/microarray/protocol.html
www.nhgri.gov/DIR/LCG/15K/HTML/protocol.html
www.nucleus.cshl.org/wigler
www.protocol-online.net/molbio/DNA/dna_microarray.html
www.tigr.org/tdb/microarray
18. Two basic substrates commonly used for cDNA printing
are glass and membrane filters
Chemically treated microscope glass slides are the most
widely used support
Microarray, Microscope Slide,80000 Spots, 10000-20000 Spots
Macroarray, Nylon Membrane, 500,-18000 Spots
Micro or Macro
19. RNA Preparation
No difference between total RNA or mRNA
Type of tissue might have profound effect on extraction
process. 100 -200 µg of RNA is needed/slide
Laser captured microdissection (LCM) , incorporation of a
PCR step
20. Sample Labeling
Most microarray utilize two fluorophores,
Cyanine3(Green emission) and Cyanine5 (Red emission)
They have different size and different ability
for incorporation in cDNA
A single round of transcription is used to generate
a labeled cDNA probe (RT-PCR)
21. Data Analysis
Normalization
First step is during scanning, when sensitivity of
detection is adjusted by the laser voltage
Gene expression value can be expressed relative
to the expression of housekeeping genes
In the absence of control genes, normalization to the median
microarray value is popular
No consensus, ANOVA
Clustering (categorizing genes according to their pattern of expression)
22. Analyzed gene changes are often expressed as a fold increase
either greater than twofold or less than 0.5 fold (DeRisi)
How Much is Significant???
With a large number of microarrays, small changes can be statistically valid
Elcock et al. detected 1.1 fold changes with 95 % confidence interval when
each experimental sample was hybridized to
seven microarray slides (with two replicate spots for each gene)
Derisi et al.Nat Genet 1996:14:457-60
23. Housekeeping genes
These are genes that are expressed constitutively and their level of
expression is thought to be stable, regardless of the sample used (β
Actin, Cyclophilin, GAPDH)
DeRisi used 90 housekeeping genes and found that changes that
were <0.5 and > 2.4 were acceptable
β Actin is one of the most commonly used housekeeping genes
and it has been shown to be downregulated in heat shock experiments
In fact, there is an appreciable amount of literature available to
suggest that there is no such thing as housekeeping gene
24. DNA microarray represents a developing technology, there remain
substantial obstacles in the design and analysis of these microarray
There are no globally accepted rules or standards
for performing controlled microarray experiments
A good experiments include more control component then
the real comparison
Accuracy and Precision
25. Principles of Q.C in DNA Microarray
Down-Scaling of an experiment makes it generally
sensitive to external and internal fluctuation
Replication of each experiments on multiple array
Dual labeling, swapping the dyes for control and treated
sample
Using a large number of controls on every array
26. Controls
mRNA from genes that are not homologous to the organism understudy (Arabidopsis)
cDNA from the organism with high, medium and
low expression represented on the array (sensitivity)
Cold DNA (e.g., calf thymus DNA, yeast tRNA)
is added to block nonspecific annealing
Spots of DNA from another organism whose
mRNA is not represented in the sample (Background)
Total genomic DNA or cDNA clones of common contaminant such
as E.Coli and yeast are represented in the array to monitor for contamination
27. Ontario Cancer Institute
Spotted Array
Advantages
Gene discovery
Optimal size(specific hybridization)
Available technology
Disadvantages
Clones processing is cumbersome
Lower density than chips
Cross hybridization(repetitive sequence)
28. Affymetrix Genechip
Biotinylated cRNA is synthesized from cDNA
phycoerthrin linked to avidin is used for labeling
Each sample hybridized separately
Advantages
High density chip
Consistent and uniform geometry
Single Nucleotide Polymorphisms
No need for maintaining cDNA clones
Disadvantages
Sequence data required
Oligonucleotid selection rules
are not well defined
Not best target for hybridization
Expensive
29. Rajeevan et al. estimated that 30% of
microarray results are false-positive
Rajeevan et al. J Mol Diag 2001-3-26-31
Microarray findings should be confirmed,at least
by one of the low-throughput gene expression methods
DNA microarray technology is in its infancy
Application of microarray in diabetes
is not born or at most is premature
30. Many genes are expressed constitutively and regulation
of their function is at the translational or posttranslational
(ApoB ,CFTR, TCR)
To date, there has been a relatively poor correlation
between gene and protein expression.
It is likely that global proteome analysis provides a better
representation of the phenotype than does gene expression analysis
32. Mouse Genechip or spotted microarray
Systematic evaluation of insulin signaling and dyslipidemia
different tissue,time course
TZD or other drugs
Parallel study with protoemic
What can we do?
33. Expressed Sequence Tag (EST)
A Partial DNA squence derived from a cDNA clone
enough to identify the transcript which the cDNA was derived
55% of cardiovascular ESTs matches to known genes
25% with other ESTs and 20% remain unmatch(novel)
2 million human ESTs deposited in GeneBank
and used as substrate for DAN microarray
34. C.C Liew,(1994) sequenced 3500 ESTs representing 3100
cDNA from adult human heart(First cadiovascular catalogue of genes)
The number of cardiovascular ESTs increased to 85,000 (1997)
The latest number(2001) is 111,224 cardiovascular ESTs
C.C.Liew:PNAS,1994;91-10645-10649
C.C.Liew: Circulation, 1997;96:4146-4203
C.C.Liew: J Mol Cell Cardiol, 2001,33,1879-1886
The largest cardiovascular cDNA microarray constructed (10,368 ESTs)
C.C.Liew. BBRC, 2000,280-964-969
Cadiovascular ESTs
35. The number of genes encoded by the Human genome has been
estimated ∼ 32,000 - 38,000.
Between 21,000 - 27,000 genes are expressed in the cardiovascular system
Lack of information
No cDNA Library for Atherosclerotic plaques
Only 5% of total ESTs deposited in GeneBank derived from cardiovscular tissue
ESTs from cardiovascular tissues or cell type
or from diseased specimens remain limited
36. Cardiovascular EST data from most model organisms are almost nonexistent
The construction of cardiovascular gene databases at different
stages of pathalogy cast light on the complex genetic
mechanisms underlying disease of cadiovascular system
DNA microarray technology is in infancy
DNA microarray in atherosclerosis was not
born or at least is premature
Premature
37. First study dealing with differential gene expression in whole-mount
specimens of rupture plaques using macroarray
Suppression Subtractive Hybridization (SSH) technique isolates low abundant
sequence that might not be isolated by use of microarray technology
Mammalian mRNA population
20% Abundant transcript (1000-12000 copies/cell)
25% Medium abundant (100-1000 copies/cell)
% 50 small number copies (< 13 copies/cell)
Mammalian mRNA encoding proteins that regular cellular
behavior are expressed at low abundence
39. Prelipin is unlikely to be the sole marker of rupture
The author used only 10% of differentially expressed gene for doing macroarray
A large effort at macroarray and then sequencing would have yield more differences
An alternative would be to hybridized the subtractand against a large array
Other alternative is the isolation of cell type-specific genes
(LCM) rather than plaque-type-specific genes
40. Perilipin was the known gene that unregulated (confirmed by RT-PCR) 8 of 10
ruptured plaques expressed prelipin while expression was absent in 10 stable plaque
Prelipin is a protein which present on the surface layer of
intracellular lipid droplets in adipocyte and prevent lipolysis
They speculated that this will result in increased lipid
retention and plaque destabilization
β actin was down regulated in ruptured plaques
The down regulation of one gene was not confirmed by RT-PCR
41. K.j.Haley et al. Treated cultured Human aortic SMC with TNFα and
used DNA microarray with 8600 genes to monitor gene expression
Marked increase in eotaxin confirmed with northern blotting
Immunohistochemical analysis demonstrated overexpression of
eotaxin and its receptor in the Human atheroma(SMC)
Circulation;2000:102:2185-2189 Bostom-Harvard
42. McCaffrey et al. compared transcript profile of fibrous cap vs adjacent media
of 13 patients ,using macroarray (membrane 588 known genes)
Early growth response gene(Egr-1) was highly
expressed in lesion (confirmed by RT-PCR)
Many Erg-1 inducible genes including PDGF , TGF-β and ICAM-1
were also strongly elevated in the lesion
Immunocytochemistry indicated that Egr-1 was expressed in SMC
β ACTIN and GAPDH were use as houskeeping gene
J.C.I 2000,105:653-662 Cornell University
43. L.D Adams, S.M Schwartz, University of Washington
Adams et al. Compared gene expression of media of aorta and
vena cava, using cDNA microarray of 4048 known genes
68 genes had consistent elevation in message expression the aorta
The most differentially gene was Regulator of G P rotein Signaling (RGS5)
Northern analysis and in situ hybridization were used to confirm the results
Circulation Research 2000.8.623
Role of Lipid Rafts in AMPA Receptor Trafficking and Synaptic Plasticity
Last ten years has been witness of emerging the concept of lipid rafts which has
changed and revolutionized the classical two-dimensional "fluid mosaic" model of
plasma membrane (Singer & Nicolson 1972). The new plasma membrane model or so
called "liquid-ordered" membrane is based on the existence of organized, detergent
resistance discrete detergent resistance microdomain of plasma membrane named lipid
rafts. Rafts are membrane subdomains, enriched in cholesterol and sphingolipids. These
microdomains act as plat forms for conducting a variety of cellular functions, such as
vesicular trafficking and signal transduction (recently reviewed by Simons K, Toomre D,
Nature Reviews, 2000, 1:31-39; Galbiati F., et al. Cell, 2001, 106:403-411).
Recent data supports that manipulation of cellular lipid composition especially
cholesterol and fatty acid contents of plasma membrane bilayer disrupt lipid
microdomains integrity, which can subsequently modulate signal transduction and
membrane trafficking. There are several classical methods to disrupt rafts integrity
including cholesterol sequestration (by using antibiotics such as filipin or nistatin; or by
using pore-forming agents such as saponin or digitonin), cholesterol depletion (by
methyl-β -cyclodextrin), inhibition of cholesterol synthesis (by statins), and perturbation
of raft stability (by using exogenous cholesterol, exogenous gangliosides, exogenous
polyunsaturated fatty acids).
Several important enzymes and signaling proteins such as insulin receptors,
PDGF, eNOS, CD36, src-family of tyrosine kinases are localized in lipid rafts (Ref: ).
More recently Suzuki et al. (Suzuki T., et al. 2001, Mol. Brain. Res. 89:20-28) reported
evidences for localization of AMPA-type glutamate receptors in the dendritic rafts.
Glutamate receptors (AMPAs, NMDARs) activities are essential to many neurological
functions. Overactivity of these receptors can cause neurological death as a result of
excitotoxicity. Excitotoxicity is a key event leading to neuronal injury in stroke patients.
Recent evidence supports central role of AMPA receptors in the pathologies caused by
brain ischemia. Although the underlying mechanism (s) are not fully understood,
modulating AMPA receptors have been shown to be neuroprotoctive. Therefore
44. R.M Lawn et al. examined the response of macrophages to exposure to
oxidized LDL, using microarray containing 10000 Human genes
268 genes were found to be at least twofold regulated
Real Time RT-PCR was used to confirm the results
Orphan nuclear receptors (PPARγ, LXR and RXR) and ABC1 were
among genes which unregulated after exposure
J.B.C 2000:275;48, 37324-37332
45. L.A Mcintire et al. identified 52 genes with altered expression under shear stress
Using DNA microarray in primary human umbilical vein endothelial cells
Significant increases in mRNA levels for 32 and significant
decreases in expression for 20 genes were reported
The most enhanced genes were cytocromes P45 1A1 and 1B1
and human prostaglandin transporter
Most dramatically decreased were connective tissue growth factor and endotheline-1
Northern blot analysis confirmed the results obtained on microarray
PNAS2001, 98:8955-8960 Rice University