Larger plaques

The pin hole seen at the center of some positives and referred to in the introduction to Section 3.1.3., should not be confused with the larger plaques of the second or later screening that have unstained centers. The plaques referred to earlier look like normal positive plaques on the filter, except that when viewed with a light shining from behind, the light can be seen shining through the filter. 

Passaged virus can be plaqued under concentrations of drug known to inhibit the plaque size of the parent virus. Larger plaques can be picked as potential resistant variants. 

Coumarin/warfarin, given at a typical dosage of 4 to 5 mg/day, prevents the deleterious formation in the bloodstream of small blood clots and thus reduces the risk of heart attacks and strokes for individuals whose arteries contain sclerotic plaques. Taken in much larger doses, as for example in rodent poisons, Coumarin/warfarin can cause massive hemorrhages and death. 

Amyloid protein A 42-amino acid protein found in the core of the microscopic senile plaques in the brains of individuals with Alzheimer s disease, p-amyloid protein is synthesised from the much larger amyloid precursor protein (APP). 

IL-6 participates in both atherogenesis and inflammatory processes. In one interesting mouse model that was double deficient at the apoE and IL-6 loci, animals displayed similar hypercholesterolemia compared to apoE-null mice, but disclosed larger and more calcified lesions at 1 year of age (Klinge 2001). Thus, IL-6 appears to be involved at the fibrous plaque stage of the atherosclerotic process. Moreover, IL-6 is a key factor in the generation of the hepatic acute-phase response and so increases the levels of CRP, fibrinogen, platelet... 

A protein known as the amyloid precursor protein (APP) spans the plasma membrane of the neurone. It possesses an extracellular domain but its function is unknown. The extracellular domain is partially hydrolised by proteolytic enzymes, known as secretases. One of the products is the amyloid peptide, of which there are two forms. The larger form, contains 42 amino acids and readily polymerises to form plaques in the extracellular space, damaging the neurones. Some sufferers possess a mutated form of the APP protein which more readily produces the larger peptide upon proteolysis, so that more toxic plaques are produced. It is the progressive accumulation of these plaques that is considered to be one cause of Alzheimer s disease. 

The effect of butadiene exposure on arteriosclerotic plaque development was assessed in white leghorn cockerels exposed for 6 h per day on five days per week for 16 weeks to 20 ppm (44 mg/m ) butadiene. Plaque frequency and size in the abdominal aorta wall were determined for butadiene-exposed animals and controls. Plaques were larger for butadiene-exposed animals than for corresponding air controls and the authors concluded that butadiene exposure markedly accelerated arteriosclerotic plaque development. Since... 

Alzheimer s disease (AD) along with vascular and mixed dementia is the commonest form of dementia affecting older people and accounts for 60-65% of dementia cases, whereas vascular dementia and mixed dementia account for 15-20% of the cases each (1). The Brain of individuals with AD manifest two characteristic lesions senile plaques and intracellular neurofibrillary tangles of the hyperphosphorylated tau protein (2). The amyloid fi-protein (Afi) is the principal component of the senile plaques. It is a peptide of 39-43 amino acids, derived from a larger precursor, the amyloid precursor protein (APP) (Fig. 1). 

In Section 3.1.1., Step 12, the plates are incubated at 42 C for 2 h, but here they are left for 4 h. Consequently, the plaques are much larger, with a diameter of about 1 mm. 

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