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Biomedical subjects

M Hubbard

Publications and source records attributed to M Hubbard.

At least 55 records · Page 3Linked to original sources
PubMed1984

Optimal javelin trajectories.

A companion paper has treated computer simulation of javelin flight using measured lift, drag and pitching moments. In the present paper we present, categorize and discuss the relative significance of various initial conditions in such a simulation. Since the differential equations describing flight are autonomous, the eventual javelin range and entry angle are unique functions of the initial conditions. A series of successively less constrained optimum solutions is defined, the last of which is the global optimum javelin trajectory. Sensitivities of these trajectories to perturbations from the optima and their implications for throwers are discussed. Finally, we investigate the effects of some design and environmental parameters on optimal initial conditions and trajectories.

Computers↗
PubMed1984

Cytoprotective effect of prostaglandin E2 in irradiated rat ileum.

Radiation injury to the gastrointestinal tract is an infrequent but major clinical problem. Results of previous studies have shown that prostaglandins provide cytoprotection of the gastrointestinal mucosa against a variety of noxious agents, although, prior to this study, the protection against radiation exposure had not been documented. Exteriorized segment of Sprague-Dawley rat ileum was radiated with 10 and 15 Gy (137Cs). One group of rats was pretreated with prostaglandin E2 one hour before and 24 hours after radiation injury. The rats were sacrificed three and five days following radiation injury. Morphometric measurement of mucosal thickness, villous height, crypt of Lieberkühn height and number of mitosis per square millimeter swath of tissue were analyzed. Also, 125IUdR and 3HTdR were injected in a group of rats radiated with 15 Gy (137Cs). 125IUdR counts per minute per milligram of dry weight and 3HTdR labeled cells were counted and analyzed. The morphometric measurements and radioactive labeled tissue counts suggest that prostaglandin E2 has a cytoprotective effect upon irradiated rat ileum. Speculations about the possible mechanism and usefulness of this observation are included.

Animals↗
PubMed1982

Comparison of five assays for immune complexes in the rheumatic diseases. An assessment of their validity for rheumatoid arthritis.

Clinical assessment (disease activity, severity, and extraarticular manifestations) of 101 rheumatoid arthritis patients was correlated with several laboratory tests, including 5 immune complex assays: the bovine conglutinin, 125I-Clq binding, monoclonal rheumatoid factor inhibition, Raji cell, and staphylococci binding assays. Elevated disease activity indices were most closely associated with the presence of immune complexes detected by the 125I-Clq and staphylococci binding assays. There were significant but weak correlations between the level of disease activity and the level of immune complexes as measured by the bovine conglutinin, 125I-Clq binding, Raji cell, and staphylococci binding assays. Articular disease severity, as measured by anatomic stage, was discriminated by the bovine conglutinin, monoclonal rheumatoid factor inhibition, and staphylococci binding assays. Extraarticular manifestations were best discriminated by the Raji cell and staphylococci binding assays. We concluded that the sensitivity, specificity, predictive value, and overlap of the associations were not sufficient to warrant their wide use for the diagnosis and management of rheumatoid arthritis in individual patients. Conversely, the 125I-Clq and staphylococci binding assays were as good as the erythrocyte sedimentation rate and the IgG rheumatoid factor test (the 2 best of many examined) in assessing disease activity. Further prospective studies with these assays will determine their usefulness in following rheumatoid arthritis for a prolonged period.

Antigen-Antibody Complex↗
PubMed1982

Comparison of five assays for immune complexes in the rheumatic diseases: performance characteristics of the assays.

The BCA, the 125-C1qBA, the mRF inhibition assay, Raji cell assay, and the SBA, all assays for ICs, were evaluated for their performance characteristics on the same specially prepared samples (267 sera), and results were compared by reference to a common standard. Differences in reproducibility between the tests were relatively consistent regardless of the parameter of variation examined or the internal standard used to compute results (overall rank order of variation: BCA and SBA less than C1qBA and Raji less than mRF). Larger ICs were overestimated and smaller ICs were underestimated by the assays. Intermediate (11s to 19s) complexes were detected by all the assays, but there were marked differences in sensitivity for this material (SBA greater than mRF greater than BCA greater than Raji greater than C1qBA). The correlation of IC assay results with IgG levels in clinical specimens could not be reproduced in vitro with monomeric IgG, and thus an artifactual influence of IgG levels on IC assay readouts was not the primary reason for this correlation. All assays were influenced by the presence of IgM rheumatoid factors. The effect of other serum manipulations such as polyanions, anticoagulants, and variation in complement could have been predicted from the receptor principle of each assay.

Antigen-Antibody Complex↗
PubMed1981

Endothelial cell presentation of antigen to human T cells.

Activation of human T cells requires presentation of antigen by Ia (HLA-DR in man) bearing cells of the mononuclear phagocytic series (macrophages, MO, and more recently Langerhans cells, dendritic cells, and vascular endothelial cells. Since T cells must cross endothelial barriers to enter extravascular tissues during immune reactions, we investigated the role of endothelial cells in antigen presentation. Endothelial cells were cultured from human umbilical veins and identified by classic morphology and specific markers (factor VIII related antigen, and so on). Antigen-pulsed endothelial cells were used to present antigen to MO-depleted human T cells; activation was assessed by 3H-thymidine uptake. The HLA-DR compatible endothelial cells were as effective as MO in reconstituting MO-depleted T-cell responses. The endothelial cell reconstituted responses were antigen specific, HLA-DR restricted, and blocked by monoclonal antibodies to HLA-DR framework structures. Moreover, the T-cell responses were clonal with respect to HLA-DR. A monoclonal antibody completely eliminated MO reconstitution of the MO-depleted response without diminution of endothelial cell reconstitution of the same response. Fibroblasts and smooth muscle cells cultured from the same umbilical veins could not reconstitute the MO-depleted T-cell response. These data indicate that endothelial cells play an important and distinctive role in lymphocyte triggering.

Antigens↗
PubMed1980

Human leukocyte A and B antigens in patients with prostatic adenocarcinoma.

An increasing number of diseases has been associated with specific human leukocyte antigens. A total of 100 white men with adenocarcinoma of the prostate was serotyped for 32 A and B antigens. Compared to a control population of 169 white subjects relative risks of 2 or more were associated with the antigens A11 and A29. Relative risks of 0.20 or less were associated with the antigens AW23, BW21 and BW22. None of these relative risks was significant statistically. We were unable to demonstrate a significant human leukocyte A or B antigen association with adenocarcinoma of the prostate.

Adenocarcinoma↗
PubMed1978

Surface membrane characteristics and cytochemistry of the abnormal cells in adult acute leukemia.

Membrane marker and cytochemical analyses were carried out on the abnormal cells from 70 adult acute leukemia patients. Such information may (1) supplement standard morphology and serve as a basis for a new classification scheme for acute leukemia, and (2) characterize the surface membranes of granulocyte, lymphocyte, and monocyte "progenitors." Classification of acute lymphoid leukemias solely on the basis of morphology was unsatisfactory. The presence or absence of T- or B-cell markers was helful in classifying lymphoid leukemias. Monocyte progenitors were characteristically nonspecific esterase positive and Fc-receptor and membrane-IgG positive, but poorly phagocytic. Promyelocytes and myelocytes were frequently Fc-receptor positive and consequently positive for surface immunoglobulin. Myeloblasts were characteristically Fc-receptor negative. We conclude that surface membrane markers are essential in diagnosing lymphoid leukemias and helpful in nonlymphoid acute leukemias, and that cytochemistry is essential in delineating lymphoid from nonlymphoid leukemias and in subclassifying the latter.

Acute Disease↗
PubMed1978

Antiserums for immunofluorescent enumeration of human T lymphocytes utilizing fluoresceinated staphylococcal protein A.

Five lots (100 ml or more) of heterologous antiserums specific for human T lymphocytes were prepared using human or Rhesus monkey thymocytes as immunogens. After appropriate adsorptions, these antiserums reacted by immunofluorescence with 68% of human peripheral blood mononuclear cells and 98% of human thymocytes, with E-rosette--positive cells but not with EAC-rosette--positive cells or five human B-lymphoblastoid-cell lines. Blocking experiments showed that Rhesus monkey thymocytes share thymic antigenic determinant(s) with humans. E-rosette receptors modulated independently from T-cell heteroantigens. Non-E--rosetting neoplastic T cells were identified in several patients with lymphoproliferative malignancies. Applying both the E-rosette assay and the anti-T-cell serum provides a better method of defining the biologic properties of normal and neoplastic T lymphocytes. Standardization of immunofluorescent conjugates for human T- or B-cell enumeration is simplified if large lots of well-characterized antiserums are available.

Animals↗
PubMed1975

Hemoglobin Atlanta or alpha 2 beta 2 75 Leu-Pro (E19): an unstable variant found in several members of a Caucasian family.

Hemoglobin Atlanta, alpha 2 beta 2 75 Leu-Pro (E19), has been found in several members of three generations of a Caucasian family living in metropolitan Atlanta. The abnormal hemoglobin is one of the nine unstable variants in which either a leucyl or an alanyl residue is replaced by a prolyl residue. These substitutions have been observed in the B, E, F, and G helixes of the beta chain and in the H helix of the alpha-chain. Hemoglobin Atlanta heterozygotes are mildly affected by the presence of this unstable hemoglobin.

Alanine↗
PubMed1975

Perseverance in self-perception and social perception: biased attributional processes in the debriefing paradigm.

Two experiments demonstrated that self-perceptions and social perceptions may persevere after the initial basis for such perceptions has been completely discredited. In both studies subjects first received false feedback, indicating that they had either succeeded or failed on a novel discrimination task and then were thoroughly debriefed concerning the predetermined and random nature of this outcome manipulation. In experiment 2, both the initial outcome manipulation and subsequent debriefing were watched and overheard by observers. Both actors and observers showed substantial perseverance of initial impressions concerning the actors' performance and abilities following a standard "outcome" debriefing. "Process" debriefing, in which explicit discussion of the perseverance process was provided, generally proved sufficient to eliminate erroneous self-perceptions. Biased attribution processes that might underlie perserverance phenomena and the implications of the present data for the ethical conduct of deception research are discussed.

Adolescent↗
PubMed1975

Hb Camden and Hb Hope found during routine testing.

The electrophoretically fast-moving hemoglobin variant Hb Camden [beta131 (H9) gln leads to glu] has been found in a middle-aged female suffering from pulmonary disease, and Hb Hope [beta136 (H14) gly leads to asp] which migrates just ahead and very close to Hb A was present in a young obstetrical patient with a mild hemolytic anemia.

Adult↗