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Biomedical subjects

R G Hamilton

Publications and source records attributed to R G Hamilton.

131 records · Page 8Linked to original sources
PubMed1976

Splenic imaging with 99mTc-labeled erythrocytes: a comparative study of cell-damaging methods.

Several methods of damaging red blood cells (RBCs) for splenic imaging were compared to determine the optimum approach. The RBCs from donor animals were labeled with 99mTcO4- and damaged by heat, excess acid citrate dextrose (ACD), excess Sn(II) ion, or the sulfhydryl inhibitors N-ethylmaleimide (NEM) or p-hydroxymercuribenzoate (PMB). The organ distributions of undamaged and damaged RBCs were determined in rats, and splenic imaging studies were performed in rabbits. Splenic deposition and spleen-to-liver ratios with heat- or sulfhydryl-damaged 99mTc-RBCs were significantly greater (p less than 0.001) than the values obtained using ACD or Sn(II) ion. Heat-damaging produces good splenic localization of 99mTc-RBCs but requires rigidly controlled incubation conditions. NEM-damaging provides an excellent and predictable alternative approach.

Animals↗
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Allergy testing.

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Allergens↗
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Application of immunoassay methods in the serodiagnosis of human filariasis.

To be more definitive as a serodiagnostic method, an ideal immunoassay for detection of filaria-specific antibody and filarial antigens in body fluids should identify active filarial infection and differentiate between past and present infection. It should perform well in the areas of precision, reproducibility, parallelism, and sensitivity and should use reference and quality control reagents prepared with human body fluids that contain defined amounts of filarial antigen. Moreover, a sufficient quantity of reference serum in stable form should be made available to permit interlaboratory cross-standardization. Difficulty with uniform radiolabeling of filarial antigen extracts and the interference of human antibody have combined to eliminate the competitive-binding immunoassay as a useful method. Of the noncompetitive methods evaluated, the immunoradiometric assay (IRMA) and its nonisotopic counterpart, the immunoenzymetric assay (IEMA), perform best. As a factor masking diagnostically important antigenic determinants, the variable amount of human antibody in blood interfered with all assay designs tested. Better characterization of the antigen(s) circulating in the blood or excreted into the urine of infected individuals will improve assay specificity and sensitivity and will facilitate the preparation of antibody probes more specifically targeted to filarial antigens for use in both the IRMA and IEMA.

Antibodies↗
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Exacerbation of diabetes mellitus by antibodies to exogenous insulin.

Three nonobese maturity-onset diabetic patients has worsening hyperglycemia and ketonuria unresponsive to marked increases in dose of beef/pork insulin. In each case, significant cross-reactivity with human insulin of anti-insulin antibodies generated by exogenous insulin therapy was demonstrated by competition experiments using solid phase radioimmunoassay. Normal or near normal levels of endogenous insulin secretion as determined by C-peptide radioimmunoassay were measured in the three cases. The sequence of events that we postulate to explain the initial presentation with severe hyperglycemia in each case begins with a slight deficiency in endogenous insulin reserve. Mild hyperglycemia then led to treatment with beef/pork insulin. The beef component elicited an antibody response that not only bound exogenous insulin, reducing its effectiveness, but also inactivated each patient's endogenous human insulin, provoking an exacerbation of underlying mild diabetes.

Adult↗