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Biomedical subjects

G J Hoffman

Publications and source records attributed to G J Hoffman.

9 recordsLinked to original sources
PubMed1997

An enhanced immunocytochemical method for staining bone marrow trephine sections.

AIMS: The detection of cellular antigens in fixed decalcified bone marrow trephine (BMT) sections depends on the method of processing, the nature of the antigen and antibody, antigen retrieval techniques, and the sensitivity of the immunocytochemical method. This study evaluated a tyramide enhanced avidin-biotin immunostaining method on formalin fixed decalcified BMT sections to determine whether the method could detect previously undetectable antigens. METHODS: Nineteen BMT biopsies from a range of haematological disorders were evaluated with 43 antibodies to haemopoietic antigens using horseradish peroxidase and alkaline phosphatase detection methods, using the tyramide enhanced avidin-biotin immunostaining method. RESULTS: Compared with standard avidin-biotin immunostaining methods the tyramide enhanced immunostaining method showed enhanced signal intensity, gave positive labelling for antigens that require pretreatment by other methods, and previously unreactive antigens were detected. Primary antibodies could be used at up to 200 times higher dilutions. CONCLUSION: The tyramide enhanced immunostaining method, while retaining specificity, is highly sensitive and enables an increased number and range of antigens to be detected than previously possible. The method could be applied to BMT sections for the routine diagnosis and classification of haematological disorders.

Antibodies, Monoclonal↗
PubMed1995

Surgeon work input and risk in primary versus revision total joint arthroplasty.

One hundred twenty stratified nonselected cases of primary and revision total joint arthroplasties performed between 1990 and 1992 in which complete financial and clinical data were available were reviewed. All cases were performed at a single university hospital. Compared with primary total joint arthroplasty, revision surgery involved significantly more operative time, greater blood loss, increased length of stay, and a much higher complication rate. The actual physician reimbursement was not significantly more than for primary procedures. Physician reimbursement constituted 18% of the total fees collected compared with 24% for the actual prosthesis cost. Surgeons performing revision surgery devote significantly more time and are at a higher liability than when performing primary total joint arthroplasty.

Aged↗
PubMed1986

Circulating antiovarian antibodies in premature ovarian failure.

The presence of antiovarian antibodies in sera of women with premature ovarian failure was determined by an indirect fluorescent antibody assay using human ovarian tissue. Of 27 patients, 14 had positive ovarian fluorescence, compared with zero of 24 normal cycling controls (P less than .001) and one of 22 postmenopausal controls (P less than .01). In patients with autoimmune diseases, five of 17 demonstrated positive fluorescence compared with zero of 24 premenopausal controls (P less than .01). Immunoperoxidase staining revealed antigen concentrated at the granulosa cells and oocyte in nine of the 14 ovarian failure cases. The finding that a significant proportion of patients with premature ovarian failure have circulating antiovarian antibodies confirms previous studies, but localization of peroxidase staining to granulosa cells and/or oocytes represents a new finding in this study.

Adult↗
PubMed1982

Proliferation and differentiation of hematopoietic stem cells in long-term cultures of adult hamster spleen.

We have found that in liquid cultures of spleen cells of adult Syrian hamsters of the F1D strain, the hematopoietic microenvironment is adequate to sustain proliferation of splenic stem cells for periods of greater than 4 mo, and permits granulocytic, monocytic, and megakaryocytic differentiation without secondary repopulation or addition of exogenous growth factors to the basic medium of RPMI 1640 plus 20% horse serum. Intimate topographical relations are established between spleen stromal cells and hematopoietic cell components of the culture is adherent "cell-producing" islets. Some of these islets are associated with multiple hematopoietic cell types such as myeloid, monocytic, and megakaryocytic cells. Other islets are associated with a single cell type such as megakaryocytes, which suggests a limited potential of some adherent stromal cells to direct the differentiation of precursor cells. Cultures of this type provide a simple and convenient model for investigation of the mechanisms controlling differentiation of hematopoietic stem cells, not only for granulocytic and monocytic cells, but for megakaryocytic cells as well.

Aging↗
PubMed1980

Monoclonal antibody against a 250,000-dalton glycoprotein of Epstein-Barr virus identifies a membrane antigen and a neutralizing antigen.

An antibody-secreting hybrid cell line was produced by fusion of mouse myeloma cells with splenocytes from mice immunized with virions of the B95-8 strain of Epstein-Barr Virus (EBV). The monoclonal IgG antibody was shown to have anti-EBV activity by the following criteria: (i) It reacted with the membranes and the cytoplasm of seven different EBV-producing lines, but with no nonproducing line. (ii) The individual cells identified by the murine antibody were shown to be the same cells identified by a human serum having anti-EBV activity. (iii) The antibody significantly reduced the infectivity of two independent strains of EBV (namely, P3HR1K and B95-8). The antigen being recognized was characterized by immunoprecipitations of radiolabeled EBV-producer cell lysates. A single glycoprotein with an estimated molecular weight of 250,000 was identified. It is concluded that neutralization of EBV can be achieved by an IgG-class monoclonal antibody directed against a single antigenic site on a 250,000-dalton glycoprotein, which is a constituent of the EBV virion.

Animals↗
PubMed1978

Myasthenic antibodies cross-link acetylcholine receptors to accelerate degradation.

The decrease of acetylcholine receptors at neuromuscular junctions of myasthenic patients has been attributed to an antibody-mediated autoimmune process that accelerates receptor degradation. We studied the mechanism of this process in skeletal-muscle cultures, using intact antibodies and antibody fragments. Addition of myasthenic IgG or its divalent fragment, F(ab')2, to cultures accelerated the rate of acetylcholine-receptor degradation threefold. By contrast, the monovalent fragment, Fab, from myasthenic serum had no effect on degradation, although it bound to acetylcholine receptors. Addition of a second, "piggyback" antibody to cross-link the Fab:receptor complexes resulted in a threefold increase of the degradation rate. Similarly, when acetylcholine receptors with bound alpha-bungarotoxin were cross-linked by the addition of specific antibody against alpha-bungarotoxin, the degradation rate increased approximately threefold. The effect of myasthenic patients' antibodies in accelerating degradation of acetylcholine receptors is attributed to their ability to cross-link the receptors.

Autoantibodies↗