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Biomedical subjects

G E Austin

Publications and source records attributed to G E Austin.

At least 55 records · Page 3Linked to original sources
PubMed1988

Automated marker enzyme analysis of density gradient fractions using the Cobas-Bio centrifugal analyzer.

An automated method for analytical subcellular fractionation which utilizes routinely available reagents and equipment is described. Tissues are fractionated in Percoll density gradients and marker enzyme analysis of gradient fractions is performed with the Cobas-Bio centrifugal analyzer. Manual assays for cytochrome oxidase and protein were adapted for use with the instrument along with commercially available 5'-nucleotidase, lactate dehydrogenase, and acid phosphatase assay kits. Crude liver homogenate fractions containing different levels of enzyme activity were used to examine the linearity of the enzyme assays. The assays were shown to be linear at high and low levels of activity. Within-run precision studies using high and low activity liver homogenate pools were also performed, and a coefficient of variation of less than or equal to 5.5% was obtained for all assays. This method was used to analyze subcellular fractions from a Percoll density gradient separation of mouse liver homogenate material. The method allowed for a complete marker analysis, consisting of 96 separate kinetic assays, within 2 hours. The versatility of this method and the ease with which it can be performed should expand the use of analytical subcellular fractionation in the diagnostic laboratory.

5'-Nucleotidase↗
PubMed1988

Neuritic plaque amyloid in Alzheimer's disease is highly racemized.

Neuritic plaque core amyloid protein in Alzheimer's disease brain tissue was investigated for the extent of amino acid racemization. Long-lived human proteins exhibit racemization of certain amino acids over the course of a human lifetime. Purified core amyloid was found to contain relatively large proportions of D-aspartate and D-serine, suggesting that neuritic plaque amyloid is derived from a long-lived precursor protein. Alternatively, racemization of protein amino acids may be abnormally accelerated in Alzheimer's disease.

Aged↗
PubMed1987

Laboratory test results as predictors of recurrent coronary artery stenosis following angioplasty.

A retrospective study has been conducted to examine the potential value of a battery of selected clinical laboratory tests as predictors of recurrent coronary artery stenosis following angioplasty. Data from 443 patients (including 325 men and 118 women) who had undergone coronary angioplasty were analyzed. Total men, total women, aspirin-treated men, and aspirin-treated women received separate statistical treatment. The only statistically significant difference in mean laboratory values between success (no recurrent stenosis) and recurrence groups was for serum cholesterol in aspirin-treated women, where the recurrence group showed a higher value than the success group. Multiple logistic regression showed a statistically significant association between elevated mean cholesterol and low mean hemoglobin concentration and recurrence in the female aspirin-treated group. Although only a small number of the laboratory test results fell outside normal laboratory reference ranges, we noted that for some tests, patients with extreme values predominantly developed recurrent stenosis while for certain other tests they were mainly successful. For example, seven of eight male diabetics with plasma glucose concentrations above 9.4 mmol/L (170 mg/dL) developed recurrence, while recurrent stenosis did not occur in any of six men with a bleeding time greater than twice normal. The results of these studies do not support the hypothesis that lipoprotein, coagulation, and platelet factors influence the development of recurrent stenosis in the majority of patients, although abnormalities in certain of these parameters may contribute to the process in specific cases.

Aged↗
PubMed1987

Immunohistochemical staining for apolipoprotein B in human sarcomas.

A study of immunocytochemical staining for apolipoprotein B (apo B) in 52 human sarcomas and eight benign soft-tissue tumors is described. A peroxidase-antiperoxidase technique was employed using a rabbit anti-apo B antiserum. All 27 liposarcomas examined were positive for apo B, and 23 of these tumors showed at least 2-plus staining on a scale of 0 to 3 plus. Of the ten myxoid liposarcomas within this group, seven showed 2-plus or 3-plus staining, while the other three stained 1 plus. By contrast, 11 of 13 malignant fibrous histiocytomas were negative for apo B; the remainder showed 1-plus staining. Myxoid areas present in three of these cases were negative for apo B. Five of seven rhabdomyosarcomas stained at least 2 plus for apo B. Both benign and malignant peripheral nerve sheath tumors showed no consistent pattern of staining. We conclude that apo B immunocytochemical staining tends to be high in tumors whose normal tissue counterparts exhibit relatively large numbers of low-density lipoprotein receptors. Furthermore, immunoperoxidase staining for apo B should be a useful adjunct in the evaluation of soft-tissue sarcomas, particularly in cases with myxoid differentiation.

Apolipoproteins B↗
PubMed1987

Nonenzymatic glycation of immunoglobulins does not impair antigen-antibody binding.

We glycated immunoglobulins from commercial kits designed to measure human ferritin, thyrotropin, and transferrin, and compared the calibration curves for assays utilizing glycated antibodies with those of assays utilizing non-glycated antibodies. Glycation was verified by borate affinity chromatography and assay with thiobarbituric acid reagent. We found no evidence that antigen-antibody binding is impaired by nonenzymatic glycation of antibodies. Our results provide no evidence in support of the supposition that glycation may be a contributory factor in the decreased resistance of diabetics to infection.

Antibodies↗
PubMed1987

Non-enzymic glycation of individual plasma proteins in normoglycemic and hyperglycemic patients.

Diabetic patients in poor glycemic control show increased glycation of total plasma proteins, but little is yet known about the relative extents to which the various individual proteins are glycated. Thus, we studied the non-enzymic glycation of several major plasma proteins and plasma protein fractions in normal and diabetic patients. In vivo glycation for most plasma proteins was very low in non-diabetic patients, only gamma globulin showing more than 5% glycation. In diabetic plasmas, glycation was much greater, immunoglobulins again showing the greatest proportion, followed in descending order by albumin, complement C3, fibrinogen, transferrin, haptoglobin, and alpha-1-antitrypsin. When plasma proteins were glycated in vitro, this order was IgG greater than complement C3 greater than albumin greater than transferrin greater than haptoglobin greater than alpha-1-antitrypsin. In general, proteins with the longest biological half-lives, such as IgG and albumin, showed the greatest in vivo glycation. On the other hand, proteins with high intrinsic glycability, such as complement C3, showed moderate glycation, despite a short half-life. Except for albumin, more basic proteins showed greater glycation than acidic proteins, but there was poor correlation between mole percent lysine and glycation. Evidently the relative extents of glycation of different plasma proteins are a complex function of integrated glucose concentrations over time and of the half-life and chemical characteristics of each protein.

Blood Protein Electrophoresis↗
PubMed1986

Biclonal gammopathy (IgG kappa and IgG lambda) in a patient with non-Hodgkin's lymphoma.

We report a case of non-Hodgkin's malignant lymphoma with biclonal gammopathy (IgG kappa and IgG lambda) involving both serum and urine. Detailed immunologic studies of the tumor disclosed two morphologically indistinguishable clones of cells that were responsible for the production of the two monoclonal immunoglobulins. This, to our knowledge, is the first documented case of a biclonal gammopathy involving a single heavy-chain class with both kappa and lambda light chains in a non-Hodgkin's lymphoma. Lesions resembling lymphomas must not be assumed to be inflammatory simply because the cells express both kappa and lambda antigens.

Aged↗
PubMed1986

Laser densitometric analysis of class I HLA antigen expression by corneal epithelium.

Laser densitometric analysis of immunoperoxidase stained tissue was used to quantitate class I HLA (HLA-A,B,C) antigen expression by human corneal epithelium. Frozen sections of human donor corneas stored in modified McCarey-Kaufman medium for less than 24 hr were evaluated for class I HLA antigen by an indirect immunoperoxidase technique using a monoclonal antibody reactive against a class I HLA antigen determinant. Photomicrographs of stained epithelium taken under standardized conditions were evaluated by laser densitometry. Measurements from peripheral and central corneal epithelium on the same tissue section were compared. Total stain, stain density, and stain intensity were higher for peripheral than for central corneal epithelium, indicating that class I HLA antigen expression is greater for peripheral than for central epithelium.

Adult↗
PubMed1986

Sensitivity of isoelectric focusing, ion exchange, and affinity chromatography to labile glycated hemoglobin.

We examined the effect of labile glycated hemoglobin on measurements of glycated hemoglobin by several commercial procedures. Erythrocytes from diabetic and nondiabetic patients were incubated in vitro with various concentrations of glucose, to generate labile glycated hemoglobin, and the species of glycated and nonglycated hemoglobin in each sample were identified by isoelectric focusing. Glycated hemoglobin was then assayed by the Bio-Rad A1 column method (I), the Bio-Rad A1c column method (II), and the Pierce affinity column method (III). I was sensitive to the labile (aldimine) fraction of glycated hemoglobin, and percentages of glycated hemoglobin so determined represented the sum of the labile fraction plus hemoglobin A1c and other stable glycated species. This spurious increase in glycated hemoglobin concentration by the aldimine could be obviated by any of three wash procedures, which eliminated the labile fraction from the samples: incubating the erythrocytes (a) in phosphate-buffered saline (pH 7.4) for 18 h at 22 degrees C, (b) in 100 mmol/L citrate (pH 5.0) for 30 min at 37 degrees C, or (c) in saline containing, per liter, 30 mmol of semicarbazide and 12 mmol of aniline hydrochloride (pH 5.0) for 30 min at 37 degrees C. Methods II and III did not detect the labile fraction. However, treatments a-c decreased the concentrations of stable glycated hemoglobin as determined by all three column-chromatographic methods as compared with unwashed sample. By isoelectric focusing we determined that blood with high glucose content had concentrations of aldimine roughly proportional to the blood glucose concentration. The kinetics of formation of labile glycated hemoglobin in these cells were consistent with the reported rate constants determined by using purified hemoglobin preparations in vitro.

Chromatography, Affinity↗
PubMed1985

Intimal proliferation of smooth muscle cells as an explanation for recurrent coronary artery stenosis after percutaneous transluminal coronary angioplasty.

The pathologic changes in the coronary arteries of three patients who died 5, 17 and 62 days, respectively, after percutaneous transluminal coronary angioplasty were studied. Changes in the vessel wall seen early after angioplasty included focal denudation of the endothelium, splits in the intima extending to and along the inner aspect of the media, focal intimal necrosis and adventitial hemorrhage. Extensive medial dissections were seen in the coronary arteries of the two patients who died 5 and 17 days after coronary angioplasty. Fibrin was deposited on the surface of the intima, within intimal cracks and in areas of intimal and medial necrosis. Focal proliferation of smooth muscle cells was prominent on neointimal surfaces of the coronary artery from the patient who died 17 days after angioplasty. The previously dilated coronary segment from the patient who died 62 days after angioplasty was stenosed by an extensive recent proliferation of smooth muscle cells that were distributed over the entire circumference of the intimal surface as well as within gaps in the old atherosclerotic plaques. This type of intimal proliferation would appear to be responsible for the recurrent coronary artery stenosis that develops in some patients after coronary angioplasty.

Adult↗
PubMed1984

Comparison of phosphotungstate and dextran sulfate-Mg2+ precipitation procedures for determination of high density lipoprotein cholesterol.

Because of the controversy over the best method for assaying high density lipoprotein (HDL) cholesterol in the clinical laboratory, a commonly used phosphotungstate method for precipitating low density and very low density lipoproteins (LDL and VLDL) was compared with a recently recommended dextran sulfate precipitation method. The accuracy and precision of HDL cholesterol determinations were similar for both methods. Either of these procedures would appear to be equally satisfactory for the assay of HDL cholesterol in the clinical laboratory.

Apolipoprotein A-I↗
PubMed1984

The effect of storage conditions on ion exchange and affinity chromatographic assays for glycated hemoglobin.

Experiments were performed to evaluate the effect on glycated hemoglobin determinations when erythrocytes were stored under various conditions. We studied the influence of time, temperature, glucose concentration, and pH on results obtained by three commercially available column chromatographic procedures designed to quantify glycated hemoglobin. An affinity chromatographic procedure which measures total glycated hemoglobins (GHb) was compared with two ion-exchange column methods. One ion-exchange method measures total hemoglobin A1 and the other is purported to measure hemoglobin A1c. Stability studies were performed using specimens from nondiabetics and diabetics, supplemented in vitro with glucose at pH 7.4 and pH 5.0. Results obtained from the A1c and the GHb tests were unchanged over time for samples stored under the described conditions. Erythrocytes were incubated with glucose to produce labile glycated hemoglobin and assayed before and after overnight incubations in saline. These experiments showed that the A1c and GHb assays were unaffected by the presence of labile glycated hemoglobin. Column fractions were analyzed by isoelectric focusing and scanned with a laser densitometer for quantitative assessment of hemoglobin species found in each fraction. These experiments showed that the three column methods measure very different hemoglobin species. Focusing of eluates from the A1 and GHb tests revealed carryover of several hemoglobin species into the measured fractions, while the A1c test was found to be much more specific for HbA1c. Our data suggest that it may be possible to analyze glycated hemoglobins in samples transported to a reference laboratory without special treatment.

Chromatography, Affinity↗
PubMed1984

Cricopharyngeal muscle hypertrophy: radiologic-anatomic correlation.

There is a divergence of opinion concerning the cricopharyngeal muscle defect commonly seen in the pharyngoesophageal area on barium esophagram. Some observers believe this defect is the result of neuromuscular dysfunction with the demonstration of the unrelaxed muscle bundle; however, others believe it is the result of actual hypertrophy of the cricopharyngeal muscle. Radiologic and pathologic study of 24 unselected autopsy cases revealed cricopharyngeal hypertrophy in 13 cases by radiologic criteria. Histologic examination revealed that the cricopharyngeal muscle thickness was uniformly greater in these cases than in the radiographically normal cases. The cricopharyngeal muscle defect is associated with actual hypertrophy of the cricopharyngeal muscle in many cases.

Autopsy↗
PubMed1984

Gender and pre-atherosclerotic lesions. Effects on prevalence in human abdominal aortas.

Gross and microscopic examination of equivalent segments of abdominal aortas obtained at autopsy from 39 male patients aged 10 to 30 years (mean, 20.5 years) and 37 female patients aged 9 to 30 years (mean, 20.9 years) revealed no significant difference in the prevalence of aortic pre-atherosclerotic lesions in male v female patients. The prevalence of fatty streaks and early and late fibromusculoelastic lesions did not change significantly with increasing age, suggesting that in the abdominal aorta, the majority of precursor lesions for atherosclerosis are already present by 15 years of age. These findings suggest that the reduced severity of atherosclerosis in female patients is not due to the presence of smaller numbers (or extent) of precursor lesions, but rather to slower progression of these lesions in female patients.

Adolescent↗
PubMed1983

Coronary artery spasm at the site of angioplasty in the first 2 months after successful percutaneous transluminal coronary angioplasty.

The clinical course of five patients manifesting coronary artery spasm at the site of previous successful percutaneous coronary angioplasty is reviewed. All patients showed this spasm on hemodynamically insignificant (less than 50% diameter narrowing) obstruction. Four patients did not respond to therapy with calcium channel antagonists and nitrates and subsequently developed recurrent stenosis. One patient died 2 months after angioplasty and 1 day after coronary bypass surgery. Pathologic study at the site of angioplasty revealed new artherosclerotic disease. Coronary spasm may occur during the healing period after coronary angioplasty and should be distinguished from fixed obstruction.

Adult↗