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Biomedical subjects

R Ryder

Publications and source records attributed to R Ryder.

At least 19 recordsLinked to original sources
PubMed1992

Effect of daily immersion on the edema of pregnancy.

To evaluate whether pregnant women become refractory to the effects of immersion, we studied 11 healthy women from 26 to 38 weeks' gestation, immersed in 34 degrees C shoulder-deep water for 4 or 5 consecutive days. The daily immersion diuresis showed no change throughout the study (p = 0.98: mean, 145 ml, 159 ml, 159 ml, 173 ml, 184 ml, day 1 through day 5, respectively). The range of urine volumes was broad, 35 to 675 ml, depending on the subject's degree of edema. Immersion produced a significantly larger diuresis compared with preimmersion values, 162 ml versus 110 ml. Maternal blood pressure and heart rate consistently fell during immersion, and this effect was maintained for each day studied. The subjects' hematocrit, hemoglobin, and total protein were unchanged from a preimmersion sample on day 1 to a postimmersion sample on the last day of the study. The results of this study indicate that pregnant women do not become refractory to the hemodynamic and diuretic effects of immersion.

Adult↗
PubMed1992

The impact of human immunodeficiency virus infection on the epidemiology and treatment of Trypanosoma brucei gambiense sleeping sickness in Nioki, Zaire.

To determine if there is an association between human immunodeficiency virus type 1 (HIV-1) infection and Trypanosoma brucei gambiense sleeping sickness, all incident cases of trypanosomiasis and a control group of blood donors presenting to the same rural hospital in Zaire were tested for anti-human immunodeficiency virus type 1 (anti-HIV-1) antibodies. There was no significant difference in the prevalence of HIV-1 infection between the two groups (7 of 220, [3.2%] for the incident cases and 8 of 388 [2.1%] for the blood donors; P = 0.56). Among the three HIV-1 seropositive incident cases of trypanosomiasis treated with difluoromethylornithine, two (67%) relapsed after treatment compared with four of 39 (10%) HIV-1 seronegative incident cases treated with the same drug (P = 0.05). These findings suggest that at the present time, HIV-1 infection is not having a significant impact on the incidence of T. brucei gambiense sleeping sickness in rural Zaire, but the possibility that incident cases of trypanosomiasis concurrently infected with HIV-1 may be at higher risk of treatment failure warrants further investigation.

Adolescent↗
PubMed1991

Knowledge, attitudes and beliefs about HIV infection and AIDS among healthy factory workers and their wives, Kinshasa, Zaire.

As a first step in designing an AIDS prevention program at a large factory in Kinshasa, Zaire, we collected information on attitudes towards human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) from factory foremen and their wives. Trained moderators conducted twelve focus group discussions (from November through December 1987) that addressed knowledge, attitudes and beliefs about HIV infection and AIDS. In general, participants were familiar with HIV infection and AIDS and considered these conditions leading health problems in Kinshasa. Although participants had a fairly accurate understanding of the causes of HIV infection, modes of transmission and preventive measures, many myths and misconceptions existed. Many participants did not believe that condom use would consistently prevent infection through sexual intercourse. Participants strongly favored the counseling of seropositive persons but showed less consensus about whether the spouse of a seropositive person should be notified of the partner's test result. Participants predicted that couples in which one member is seropositive and the other is not would experience marital discord and friction with family, neighbors and co-workers. These findings were applied to the development of a counseling and educational program for seropositive factory employees and their spouses.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Seroconversion rate, mortality, and clinical manifestations associated with the receipt of a human immunodeficiency virus-infected blood transfusion in Kinshasa, Zaire.

To evaluate the consequences of receiving human immunodeficiency virus type 1 (HIV-1)-seropositive blood, 90 HIV-1-seronegative recipients of HIV-1-seropositive blood (case patients) and 90 HIV-1-seronegative recipients of HIV-1-seronegative blood, matched for age, sex, number of transfusions, diagnosis, and severity of illness (controls), were followed for 12 months after transfusion at Mama Yemo Hospital in Kinshasa, Zaire. Of case patients and controls, 72% were children transfused for anemia caused by malaria. Of the 46 case patients case patients alive 6 months after transfusion and for whom HIV-1 serologic results were obtained, 44 (96%) had seroconverted. Significantly more case patients (47%) than controls (16%) died within 1 year after transfusion (P less than .001). In the first 3 months after transfusion, fatigue, diarrhea, fever, cough, pruritus, pallor, oral candidiasis, polyadenopathy, hepatosplenomegaly, and rhinorrhea were observed more often among seroconverters than controls (P less than .04). Six percent of case patients and no controls had developed clinical AIDS after 12 months of follow-up. These findings underscore the urgent need for appropriate HIV screening facilities in transfusion centers worldwide.

Adolescent↗
PubMed1991

Prevalence of HIV-1 p24 antigenemia in African and North American populations and correlation with clinical status.

Sera from 622 individuals and culture supernatants from three HIV-1 viral isolates were assayed for HIV-1 p24 antigen to investigate the frequency of p24 antigenemia in African and North American populations using three commercial HIV-1 p24 antigen assays (Coulter, Du Pont, and Abbott). The prevalence of p24 antigenemia in 89 hospitalized Zairian AIDS patients was significantly lower than in 47 clinically comparable AIDS patients in the USA (17 versus 48%, P less than 0.0001). Prevalence of p24 antigenemia in sera from 200 asymptomatic HIV-1-infected individuals was also lower in individuals from Zaire compared with 83 individuals in the USA (3.5 versus 7%). In African individuals, antigenemia prevalence increased with advanced clinical status: 8% in ambulatory AIDS patients, 17% in hospitalized AIDS patients and 18% in postmortem AIDS patients. Acid hydrolysis treatment of sera from 63 Zairian AIDS patients initially negative for p24 antigen showed an 11% positivity rate confirmed by neutralization, suggesting that immune complexing of p24 antigen may play a role in the observed lower p24 antigenemia rates reported for African individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Incidence of malaria and efficacy of oral quinine in patients recently infected with human immunodeficiency virus in Kinshasa, Zaire.

There is concern that the impaired cell mediated immunity caused by the human immunodeficiency virus may increase the risk of severity of Plasmodium falciparum infection and could lead eventually to a decreased response to standard antimalarial treatment. In 1986, at Mama Yemo Hospital, Kinshasa, Zaire, the incidence of malaria was determined in a cohort of 59 patients who had recently acquired HIV-I infection through blood transfusion and in a cohort of 83 HIV-I seronegative controls who were recipients of HIV-I seronegative blood. All cohort patients were asked to visit the study physician whenever they developed fever. On each of these occasions thick film was examined for the presence of malarial parasites. HIV-I seropositive patients presented more often with episodes of fever per person month observation than HIV-I seronegative patients (P = 0.003). The total number of positive thick films per person months observation was significantly higher among HIV-I seropositive patients than among the HIV-I seronegative ones, but percentages of positive thick films per episode of fever were the same in both groups (46%). During a 5 month period, cohort patients presenting with a moderate attack of malaria were treated with oral quinine 20 mg/kg daily in two doses for 5 days. Twenty-three (92%) of 25 HIV-I seropositive patients and 28 (82%) of 34 HIV-I seronegative patients had a negative film 7 days after starting treatment. This study suggests that there seems to be no direct interaction of major clinical importance between HIV infection and malaria.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Cutaneous delayed-type hypersensitivity in patients with human immunodeficiency virus infection in Zaire.

Cutaneous delayed-type hypersensitivity (DTH) reactions were assessed by the CMI-Multitest (Merieux, Lyon, France) in patients with different stages of human immunodeficiency virus (HIV) infection in Kinshasa, Zaire. Skin tests were read after 48-72 h. A reaction to an antigen was considered positive if there was induration of greater than 2 mm. Cutaneous anergy occurred more often in HIV-seropositive patients than in healthy controls (p less than 0.001) and was most prevalent in patients with advanced HIV illness. HIV-seropositive patients with a positive tuberculin reaction were more likely to have active tuberculosis (TB) than HIV-seropositive patients without a positive tuberculin reaction (p less than 0.001). Therefore, a TB diagnosis should be pursued in HIV-seropositive patients with a positive tuberculin reaction.

Adult↗
PubMed1988

Comparison of sensitivities and specificities of latex agglutination and an enzyme-linked immunosorbent assay for detection of antibodies to the human immunodeficiency virus in African sera.

The sensitivities, specificities, and positive and negative predictive values of the Cambridge BioScience Corp. (Worcester, Mass.) human immunodeficiency virus latex agglutination assay were compared by using three different blood preparations. By using the manufacturer's standard test method with diluted sera, the sensitivity of latex agglutination was 100%, the specificity was 99.58%, and the positive and negative predictive values were 99.26 and 100%, respectively. Use of diluted whole blood or undiluted whole blood did not significantly affect the sensitivity (mean, 99.72%), specificity (mean, 99.47%), positive predictive value (mean, 99.07%), or negative predictive value (mean, 99.89%). The latex agglutination assay is a simple, rapid assay for the detection of human immunodeficiency virus that would be useful in Third World countries or other areas where enzyme-linked immunosorbent assays are not available or cannot be used.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Renal response to intravenous somatostatin in insulin-dependent diabetic patients and normal subjects.

The acute effects of iv somatostatin (SRIH; 100 micrograms/h) on the urinary flow (Uvol), effective renal plasma flow (RPF), and glomerular filtration rate (GFR) were compared with those of a control infusion of 0.15 M NaCl in nine insulin-dependent diabetic (IDD) patients of less than 10 yr disease duration and six normal subjects (NS). RPF and GFR were measured using a standard primed constant isotope infusion of [125I]iodohippurate and [51Cr]chromium EDTA. Uvol, RPF, and GFR were measured during 20-min clearance periods. During the NaCl infusion mean Uvol, RPF, and GFR were 14.1 +/- 0.2 (+/- SEM), 708 +/- 4, and 150 +/- 1 mL/min in the IDD group and 12.7 +/- 0.4, 568 +/- 5, and 110 +/- 2 mL/min in the NS group, respectively. In the IDD patients Uvol, RPF, and GFR decreased from 16.6 +/- 1.8, 670 +/- 30, 146 +/- 4 mL/min pre-SRIH to 9.2 +/- 1 (P less than 0.001), 553 +/- 25 (P less than 0.001), and 130 +/- 5 (P less than 0.001) mL/min, respectively, at 120 min during the SRIH infusion. Similarly, in the NS group mean Uvol, RPF, and GFR were 14.2 +/- 0.6, 552 +/- 15, and 112 +/- 5 mL/min pre-SRIH and decreased to 7.4 +/- 0.6 (P less than 0.001), 422 +/- 7 (P less than 0.001), and 93 +/- 3 (P less than 0.001) mL/min, respectively, after 120 min of the SRIH infusion. SRIH, therefore, had a profound effect on renal function in both IDD patients and NS, resulting in a reduction in RPF, GFR, and, as a consequence, Uvol.

Adult↗
PubMed1986

Effect of somatostatin on renal function.

Somatostatin has profound effects on both splanchnic and portal vascular beds. The effects of intravenous somatostatin (100 micrograms/h) on urinary volume, effective renal plasma flow, and glomerular filtration rate were compared with the effects of a control infusion of physiological saline in six normal subjects. Renal plasma flow and glomerular filtration rate were measured by primed constant isotope infusions of iodine-125 iodohippurate and chromium-51 edetic acid. Urinary volume, renal plasma flow, and glomerular filtration rate were measured during 20 minute clearance periods. During the control infusion urinary volume, renal plasma flow, and glomerular filtration rate remained essentially unchanged at 254 (SEM 3) ml/20 min, 568 (5) ml/min/1.73 m2, and 110 (2) ml/min/1.73 m2 respectively. From similar basal values the infusion of somatostatin led to a rapid decrease in all three variables. After 120 minutes of infusion of somatostatin urinary volume, renal plasma flow, and glomerular filtration rate were reduced to 148 (17) ml/20 min (p less than 0.01), 422 (7) ml/min/1.73 m2 (p less than 0.001), and 93 (3) ml/min/1.73 m2 (p less than 0.05) respectively. This effect on renal function should be borne in mind whenever somatostatin is used.

Adult↗
PubMed1985

Structural analysis of hepatitis B surface antigen by monoclonal antibodies.

A method has been developed for the analysis of hepatitis B surface antigen (HBsAg) antigenic structure at the molecular level that creates "fingerprints" or "signatures" of various hepatitis B viral (HBV) strains. This technique employs high affinity IgM and IgG monoclonal antibodies (anti-HBs) directed against distinct and separate determinants on HBsAg. In performing this antigenic structural analysis, separate binding curves for different monoclonal anti-HBs are generated by measuring immunoreactivity in serial dilutions of HBsAg-positive serum by radioimmunoassay. Since the HBsAg concentration in serum is unknown, the binding profiles of groups of samples are aligned by an iterative least-squares procedure to generate the numerical signature characteristic of the viral strain. The numerical signatures are then displayed on a computer-graphic plot. The signature profiles of HBsAg subtypes are a true reflection of their antigenic structure, and in vertical and horizontal transmission studies the molecular characteristics of the viral epitopes are conserved. By signature analysis we found substantial antigenic heterogeneity among the ayw3 strain both in the U.S. and France, as well as in populations of the Far East and Africa. Populations in Ethiopia, Gambia, and the Philippines were infected with two antigenically distinct HBV strains. In some newly identified HBV strains, it was found that epitopes identified by some monoclonal antibodies were absent or substantially reduced, which suggested that a genetic mutation may have occurred. Thus this study suggests that there is far more antigenic heterogeneity in HBV than previously recognized. These variants are antigenically distinct from each other at the epitope level, and were heretofore unrecognized by polyvalent anti-HBsAg antibodies.

Adult↗