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Biomedical subjects

S A Hall

Publications and source records attributed to S A Hall.

At least 37 records · Page 2Linked to original sources
PubMed1988

Utility of frozen platelets for a platelet antibody assay using flow cytometric analysis.

The immunoreactivity of a PLA1 antibody-containing serum to frozen/thawed platelets prepared by four different procedures was measured to assess the practicality of preparing a platelet reagent that could be easily stored and readily used in an immunofluorescent platelet antibody detection system. These frozen aliquots were analyzed at intervals up to 23 weeks after initial freezing and storage. For analysis, the frozen platelets were thawed, washed, resuspended to 2.5 x 10(5) platelets/mL and incubated with a dilution of fresh autologous serum that lacked platelet antibody or with a similar dilution of frozen human serum containing IgG anti-PLA1 antibody. At each interval, a freshly drawn platelet sample from the same donor was incubated in the same manner and used for comparison. All platelet mixtures were then washed and incubated with fluorescein conjugated goat F (ab')2 antihuman IgG. After repeat washing, each mixture was then analyzed with a flow cytometer for the extent of fluorescent antibody bound to each platelet mixture. Anti-PLA1 antibody reactivity with either the fresh or the frozen/thawed platelets remained stable over the period of analysis, with no significant difference in immunofluorescence with either fresh or frozen platelets as target cells. Platelet recovery following the thawing step ranged from 12% to 36% and was independent of the storage time. These studies suggest that frozen platelets can be readily used as reagents for platelet antibody assays.

Antibodies↗
PubMed1988

Platelet antibody detection using frozen pooled human lymphocyte antigen-typed platelets as target cells.

The immunoreactivity of five sera containing either iso-, auto- or allo-antiplatelet antibodies to frozen-thawed human lymphocyte antigen (HLA)-typed pooled platelets was assessed to determine the practicality of using such a platelet preparation in an immunofluorescent platelet antibody system. The platelet reagent was analyzed over an 8-week period after initial freezing and storage. Mixtures of platelets with each serum or dilutions of it were initially incubated for 1 hour, then extensively washed and incubated with fluorescein-conjugated goat F(ab')2 antihuman IgG, A, M. After repeat washing, each mixture was then analyzed using a flow cytometer to determine the relative amount of fluorescent antibody bound. Not only was each of the five sera consistently positive for the presence of an anti-platelet antibody, but the extent of immunoreactivity for each remained relatively stable over the 8-week period of analysis. The results suggest that frozen pooled HLA-typed platelets should be an invaluable reagent for screening serum samples for the presence of antiplatelet antibodies in patients who are thrombocytopenic or who are refractory to platelet transfusion therapy.

Blood Platelets↗
PubMed1987

Microcytotoxicity assay for platelet antibodies using fresh and frozen fluorescein-labeled target platelets.

We describe our results with a microtoxicity assay that uses fluorescein-labeled platelets for the detection of auto-, iso-, and allo-immune platelet antibodies. The system has a number of advantages in that it is not only rapid but can accommodate multiple test specimens, requires minimal reagents, and can utilize both fresh or frozen donor platelets as the target cells. The latter attribute may allow for the development of a platelet blood banking system with more efficient platelet cross-matching capabilities.

Antibodies↗
PubMed1986

Platelet-associated IgG assay using flow cytometric analysis.

In this study we describe an immunofluorescent assay system to measure platelet-associated immunoglobulin G levels using flow cytometric analysis. This semi-quantitative system allows ready distinction of immune from non-immune related thrombocytopenias. It is simple to perform, highly reproducible and has the advantage of requiring a minimum concentration of 5000 platelets/microliter per assay sample.

Autoimmune Diseases↗
PubMed1986

Acquired von Willebrand syndrome due to an inhibitor specific for von Willebrand factor antigens.

A patient with acquired von Willebrand syndrome associated with polycythemia rubra vera is described. Her plasma factor VIII procoagulant activity (67 U/dl) and factor VIII-related antigen (117 U/dl) were normal but no von Willebrand factor activity could be detected. Factor VIII crossed immunoelectrophoresis revealed decreased levels of less anodic polymeric forms of factor VIII. Mixture of her plasma or immunoglobulin G (IgG) fraction with normal plasma resulted in complete recovery of factor VIII activity and related antigen but no measurable von Willebrand factor activity, confirming the presence of an unique inhibitor. The limited specificity of this inhibitor to antigenic sites solely on the von Willebrand portion of the factor VIII bimolecular complex is distinct from all previous reports of this syndrome. This unique inhibitor offers a molecular probe to examine the von Willebrand factor: platelet interaction.

Antigens↗
PubMed1984

Detection of platelet antibodies by flow cytometric analysis.

A rapid, sensitive indirect immunofluorescence assay utilizing flow cytometry to detect immune-mediated thrombocytopenia is described. Fluorescein-conjugated F(ab')2 antihuman IgG or IgGAM is reacted with donor platelets after their incubation with test sera and the resulting immune complex is measured using flow cytometric analysis. With this technique excess of Ig on the platelet, expressed as a ratio of fluorescence of test sera/autologous control sera, was noted in 24 of 30 patients (80%) with immune thrombocytopenias caused by auto- or allo-antiplatelet antibodies. Twenty-four sera from nonimmune thrombocytopenic patients were consistently negative. This technique has the advantage of being highly reproducible and avoids the subjective interpretation inherent with manual immunofluorescence assays.

Antibodies↗
PubMed1983

A geriatric special-care unit: experience in a university hospital.

Responding to a perceived need for specialized care for the acutely ill elderly, a 14-bed geriatric special-care unit was established in the University of Massachusetts Hospital in January 1980. Patients were selected for admission after assessment of their potential to benefit from restorative care. Most patients were admitted from the emergency room or outpatient clinics or were scheduled admissions; a few were in-hospital transfers. This report deals with a retrospective analysis of the first 514 admissions (431 patients) to the unit. Admissions by major service were: Medicine, 64 per cent; Surgery, 14 per cent; Neurology, 10 per cent; Orthopedics, 7 per cent; and other, 5 per cent. Approximately 64 per cent of patients were between the ages of 70 and 84. The overall average length of stay per admission was 11.5 days. Mortality rate of patients undergoing surgery (n = 125) was 4 per cent. The percentage of admissions that were discharged home was 78.7 per cent. Only 7.3 per cent of admissions were discharged to a nursing home, when those that were admitted to the unit from a nursing home are excluded. The authors conclude that a special nursing unit for acutely ill elderly patients may serve several purposes in a university hospital: overall patient care may be improved; length of hospital stay may be shortened; and medical students, housestaff, and attending physicians may gain an opportunity to learn the fundamentals of geriatric medicine as demonstrated by the staff of the unit.

Aged↗
PubMed1980

VIDA II: a computerised diagnostic recording system for veterinary investigation centres in Great Britain.

"Veterinary Investigation Diagnosis Analysis" II is a computerised recording system for all the diagnoses made at 33 Government diagnostic laboratories in Great Britain. It was created in 1975 and the records of 150,000 specimens are stored on it each year. The system depends on an agreed list of 393 possible diagnoses (101 cattle, 96 sheep, 72 pigs, 71 birds and 53 for other species). Diagnostic records are sent each month to a computer centre which produces an annual record of all diagnoses made and a monthly record of the number of submissions and financial charges. The computer file can be interrogated from a terminal at the epidemiology unit Weybridge and the diagnostic records are available to research workers.

Animal Diseases↗
PubMed1978

Effects of rapeseed meal on laying hens (Gallus domesticus) in relation to fatty liver-haemorrhagic syndrome and egg taint.

Fatty liver-haemorrhagic syndrome (FLHS) occurred in the controls and was modified in hens that received a diet containing 10 per cent rapeseed meal. This diet increased the extent and severity of the hepatic haemorrhage without affecting the reticulin content of the liver but decreased the body weight and liver lipid levels and so weakened the correlation between these parameters and haemorrhage score found in FLHS. Plasma aspartate transaminase and beta-glucuronidase activities tended to increase with the score. The rapeseed meal diet also produced thyroid hypertrophy and since this was greater in the hens that produced tainted eggs and was positively correlated with the trimethylamine (TMA) content of the eggs it was postulated that rapeseed meal goitrogens may be involved as secondary factors in producing the disturbance in TMA metabolism that causes the egg taint. This abnormality was associated with a reduction in the soluble protein content of the liver, which reflected a decrease in TMA oxidase activity, but was not related to hepatic haemorrhage, steatosis or reticulolysis, or to lipid levels and the activities of lysosomal enzymes and transaminases in the plasma.

Animal Feed↗
PubMed1977

Coughing in horses--an historical aspect.

A brief historical review is given of the incidence and types of respiratory disease that occurred in Britain in the 18th and 19th centuries. The significance of poor stabling and overcrowding in the causation and spread of coughing is emphasised and its dramatic reduction by simple methods of hygiene and ventilation.

Animal Husbandry↗