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Biomedical subjects

R Redfield

Publications and source records attributed to R Redfield.

27 records · Page 2Linked to original sources
PubMed1986

Susceptibility of normal human lymphocytes to infection with HTLV-III/LAV.

Normal human peripheral blood lymphocytes were tested for their susceptibility to infection with retroviruses isolated from patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex. Of 10 normal individuals tested, lymphocytes from all subjects became infected and produced virus as detected by assay for Mg+2-dependent reverse transcriptase. Lymphocytes from different individuals were demonstrated to be either high or low producers of reverse transcriptase after infection. The kinetics of virus production were similar in cells from both high- and low-producing individuals. A significant correlation was observed between high and low viral-producing lymphocytes and expression of the Leu-3/T4 (CD4) surface molecule. Mitogen-stimulated peripheral blood lymphocytes exposed to HTLV-III/LAV manifested productive viral infection, as reflected by the appearance of early syncytia, followed by reverse transcriptase. Unstimulated peripheral blood lymphocyte cultures displayed late syncytia but no detectable reverse transcriptase upon exposure to virus. The addition of anti-human interferon-alpha did not appear to have an appreciable effect on viral production in normal peripheral blood lymphocytes exposed to the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

On the relation between joint moments and pedalling rates at constant power in bicycling.

Joint moments are of interest because they bear some relation to muscular effort and hence rider performance. The general objective of this study is to explore the relation between joint moments and pedalling rate (i.e. cadence). Joint moments are computed by modelling the leg-bicycle system as a five-bar linkage constrained to plane motion. Using dynamometer pedal force data and potentiometer crank and pedal position data, system equations are solved on a computer to produce moments at the ankle, knee and hip joints. Cadence and pedal forces are varied inversely to maintain constant power. Results indicate that average joint moments vary considerably with changes in cadence. Both hip and knee joints show an average moment which is minimum near 105 rotations min-1 for cruising cycling. It appears that an optimum rotations min-1 can be determined from a mechanical approach for any given power level and bicycle-rider geometry.

Bicycling↗
PubMed1986

Prediction of pedal forces in bicycling using optimization methods.

The bicycle-rider system is modeled as a planar five-bar linkage with pedal forces and pedal dynamics as input. The pedal force profile input is varied, maintaining constant average bicycle power, in order to obtain the optimal pedal force profile that minimizes two cost functions. One cost function is based on joint moments and the other is based on muscle stresses. Predicted (optimal) pedal profiles as well as joint moment time histories are compared to representative real data to examine cost function appropriateness. Both cost functions offer reasonable predictions of pedal forces. The muscle stress cost function, however, better predicts joint moments. Predicted muscle activity also correlates well with myoelectric data. The factors that lead to effective (i.e. low cost) pedalling are examined. Pedalling effectiveness is found to be a complex function of pedal force vector orientation and muscle mechanics.

Bicycling↗
PubMed1986

Impaired antibody-dependent cell-mediated cytotoxic activity in patients with the acquired immunodeficiency syndrome.

Since the acquired immunodeficiency syndrome (AIDS) is characterized by opportunistic infections and malignancies indicative of a profound suppression in cell-mediated immunity, we investigated the antibody-dependent cell-mediated cytotoxicity (ADCC) of peripheral blood mononuclear cells of patients with AIDS against chicken red blood cells (CRBC). A marked decrease in ADCC-CRBC activity was observed from patients with AIDS as compared to healthy controls. Furthermore, suppression in ADCC activity was seen when mononuclear cells from healthy subjects were assayed using media containing 25% or 40% sera from AIDS patients. Two of two patients with AIDS and impaired ADCC-CRBC activity were also found to have in vivo impaired reticuloendothelial system Fc-specific clearance of 51Cr-labelled, anti-Rho (D) IgG-sensitized autologous erythrocytes. These data provide further evidence of monocyte-macrophage dysfunction in AIDS and help explain the widespread occurrence of opportunistic pathogens in AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Genomic diversity of human T-lymphotropic virus type III (HTLV-III).

The DNA genomes of human T-lymphotropic virus type III (HTLV-III) isolated from 18 individuals with AIDS or who were at risk for AIDS were evaluated for evidence of variation. Although all of the 18 viral DNA's hybridized throughout their entire genomes to a full-length cloned probe of the original HTLV-III isolate, each of the 18 isolates showed a different restriction enzyme pattern. The number of restriction site differences between isolates ranged from only 1 site in 23 to at least 16 sites in 31. No particular viral genotype was associated with a particular disease state and 2 of the 18 patients had evidence of concurrent infection by more than one viral genotype. Propagation of three different viral isolates in vitro for up to 9 months did not lead to detectable changes in their restriction patterns. These findings indicate that different isolates of HTLV-III comprise a spectrum of highly related but distinguishable viruses and have important implications regarding the pathogenicity of HTLV-III and attempts to develop effective diagnostic, therapeutic, and preventive measures for this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Circulating IgA immune complexes in AIDS.

Circulating immune complexes were isolated from the serum of patients with AIDS, as well as patients with other acute and chronic viral diseases. Analysis of these immune complexes by methods of flow cytometry and by radioimmune (Raji cell) assay revealed a prevalence of IgA complexes in the serum of AIDS patients and a prevalence of IgG complexes in the serum of patients with other viral diseases. Raji cells bind immune complexes via Fc and complement (C3) receptors and may detect IgA immune complexes more efficiently than a C1q assay since IgA has no affinity for C1q.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Frequent detection and isolation of cytopathic retroviruses (HTLV-III) from patients with AIDS and at risk for AIDS.

Peripheral blood lymphocytes from patients with the acquired immunodeficiency syndrome (AIDS) or with signs or symptoms that frequently precede AIDS (pre-AIDS) were grown in vitro with added T-cell growth factor and assayed for the expression and release of human T-lymphotropic retroviruses (HTLV). Retroviruses belonging to the HTLV family and collectively designated HTLV-III were isolated from a total of 48 subjects including 18 of 21 patients wih pre-AIDS, three of four clinically normal mothers of juveniles with AIDS, 26 of 72 adult and juvenile patients with AIDS, and from one of 22 normal male homosexual subjects. No HTLV-III was detected in or isolated from 115 normal heterosexual subjects. The number of HTLV-III isolates reported here underestimates the true prevalence of the virus since many specimens were received in unsatisfactory condition. Other data show that serum samples from a high proportion of AIDS patients contain antibodies to HTLV-III. That these new isolates are members of the HTLV family but differ from the previous isolates known as HTLV-I and HTLV-II is indicated by their morphological, biological, and immunological characteristics. These results and those reported elsewhere in this issue suggest that HTLV-III may be the primary cause of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Rheumatoid arthritis and membranous glomerulonephritis: a role for immune complex dissociative techniques.

Although controversial, several reports have linked rheumatoid arthritis (RA) with membranous glomerulonephritis (MGN). In none of these studies was an infectious etiology such as hepatitis B virus (HBV) thoroughly pursued. We evaluated a patient with classic RA and MGN unassociated with nephrotoxic drugs. Although negative by routine serological methods, hepatitis B surface antigen was eventually demonstrated in the serum, using immune complex dissociative techniques, and in the renal glomeruli, using tissue immunofluorescence. A review of the literature provides no conclusive evidence for a causal relationship of RA to MGN. The renal pathogenic potential of HBV, however, is well documented. Future use of immune complex dissociative techniques and tissue immunofluorescence may be of value in clarifying otherwise unexplained MGN in the setting of RA.

Adult↗