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Biomedical subjects

A Porter

Publications and source records attributed to A Porter.

At least 19 recordsLinked to original sources
PubMed1992

Effects of amiodarone on erect and supine exercise haemodynamics and exercise capacity in patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a primary heart muscle disease associated with a high incidence of sudden death. Amiodarone is of benefit in those patients with a high risk profile for sudden death. Amiodarone has also been reported to improve symptoms dramatically in some patients with HCM but to cause functional deterioration in others. In the acute phase of oral amiodarone therapy there are few discernable changes in cardiovascular haemodynamics and the mechanisms of any beneficial effects on symptoms remain unclear. To determine the effect of amiodarone on exercise responses we measured haemodynamic indices in 10 patients during maximal supine- and symptom-limited erect treadmill exercise before and 6 weeks after amiodarone therapy. Following amiodarone therapy there was a significant reduction in resting and peak heart rate during erect exercise (76 +/- 13 vs 97 +/- 19 b.min-1; P = 0.001 and 114 +/- 26 vs 146 +/- 21 b.min-1; P = 0.001 respectively). Despite increases in peak pulmonary and systemic artery pressures with amiodarone therapy there was no difference in the peak left ventricular filling pressure or maximum cardiac output achieved. Similarly, during supine exercise the resting and peak heart rates were less following the 6 weeks amiodarone therapy. Comparison of supine and erect exercise haemodynamic indices demonstrated higher peak LV filling and higher peak systolic and pulmonary artery pressures during supine than during erect exercise (29 +/- 10 vs 25 +/- 12; P less than 0.04; 151 +/- 42 vs 126 +/- 48; P = 0.01 and 66 +/- 27 vs 62 +/- 21; P = 0.08 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

HIV-1 and HIV-2 infection in children in Abidjan, Côte d'Ivoire.

We conducted a study of 1,003 well and hospitalized children, birth to 5 years old, in Abidjan, Côte d'Ivoire, to determine the prevalence of HIV-1 and HIV-2 infection, evaluate risk factors for infection, and describe associated clinical characteristics. The overall seroprevalence was significantly higher for children in the hospital (10.8%) than for those attending the clinic (3.6%). HIV-1 was the predominant virus in both populations, comprising 87% (hospital) and 77% (clinic) of the seroreactive blood specimens. Ninety-two percent of seroreactive children of all ages had a mother who was HIV positive; 77% of seroreactive children greater than or equal to 15 months old had an HIV-infected mother. The remaining seropositive children had a history of receiving blood transfusions. Hospitalized children who were HIV-1 positive or dually seroreactive were more likely to have HIV-related clinical signs and symptoms than HIV-negative children. These findings suggest that HIV infection is an important cause of morbidity for children in Abidjan and that maternal infection is the primary risk factor for both HIV-1 and HIV-2 infection in children. Further evaluation and attention should be given to transmission, clinical characteristics, and the impact of HIV infection in children in West Africa, where both HIV-1 and HIV-2 are present.

Child, Preschool↗
PubMed1992

The long-term effects of 5-fluorouracil and sodium butyrate on human Tenon's fibroblasts.

The use of subconjunctival 5-fluorouracil (5-FU) in the first weeks after filtration surgery may ensure long-term bleb survival despite a continuing proliferative stimulus such as in eyes with neovascular glaucoma. In addition, long-term side effects may occur, such as increasing bleb thinning. To ascertain the long-term effects of 5-FU and sodium butyrate, an agent with differentiating and antiproliferative properties, we exposed proliferating human Tenon's capsule fibroblasts to different concentrations of the drugs. The cells were exposed to 5-FU for 1-12 d. The cells were subsequently observed for up to 30 d. Cell proliferation was assessed using cell counting and bromodeoxyuridine uptake, and cell viability was assessed with trypan blue uptake. 5-FU and sodium butyrate inhibited fibroblast proliferation during the treatment period. Higher concentrations of 5-FU (100 and 1000 micrograms/ml) for as little as 1 d resulted in no significant increase in the number of fibroblasts for at least 29 d after treatment was stopped, despite continued stimulation with serum. When treatment with sodium butyrate was stopped, there was greater recovery of proliferation. At a constant concentration of 1000 micrograms/ml of 5-FU for 3 or more days, or a concentration of 100 mmol/l sodium butyrate for 12 d, the entire fibroblast population gradually died over the 30 d period. Thus, short-term treatment with 5-FU may result in long-term inhibition of proliferation of fibroblasts. Long-term inhibition depends on the duration of treatment or on the concentration of 5-FU. Short-term treatment may be affecting the ability of the tissues at the bleb site to heal in the long term. Different dosage regimens may have advantages and are discussed.

Adolescent↗
PubMed1991

Cross-reactivity on western blots in HIV-1 and HIV-2 infections.

To examine cross-reactivity of antibodies to heterologous antigens, on HIV-1 and HIV-2 Western blots, we tested sera from 1362 consecutive tuberculosis (TB) patients and 2127 consecutive blood donors. Specimens positive on enzyme-linked immunosorbent assay (ELISA) for HIV-1 or HIV-2 were further characterized by synthetic peptide-based tests, and tested by HIV-1- and HIV-2-specific Western blots. Dual serologic reactivity on synthetic peptide tests was proportionately more frequent in HIV-positive TB patients than in blood donors, and HIV-2 reactivity less frequent. Positive HIV-1 Western blots were seen in 73-83% of specimens specifically characterized as positive for HIV-2 on synthetic peptide tests. Cross-reactivity to HIV-2 Western blots by HIV-1-positive specimens was significantly more frequent in TB patients (35%) than in asymptomatic donors (9%; P less than 0.001). Using recently recommended criteria for HIV-2 Western blot interpretation (presence of two env bands) reduced the overall proportion of HIV-1-positive specimens having a positive HIV-2 Western blot from 27.5 to 16.4%, with [corrected] minimal effect on sensitivity in the diagnosis of HIV-2 reactivity on specimens positive on synthetic peptide tests.

Blotting, Western↗
PubMed1990

AIDS--the leading cause of adult death in the West African City of Abidjan, Ivory Coast.

In 1988 to 1989, 698 adult cadavers in Abidjan's two largest morgues were studied, representing 38 to 43% of all adult deaths in the city over the study period, and 6 to 7% of annual deaths. Forty-one percent of male and 32% of female cadavers were infected with human immunodeficiency virus (HIV). Fifteen percent of adult male and 13% of adult female annual deaths are due to acquired immunodeficiency syndrome (AIDS). In Abidjan, AIDS is the leading cause of death and years of potential life lost in adult men, followed by unintentional injuries and tuberculosis. In women, AIDS is the second leading cause of death and premature mortality, after deaths related to pregnancy and abortion. AIDS-specific and AIDS-proportional mortality rates may be higher in other African cities where AIDS has been found for a longer time than in Abidjan.

Acquired Immunodeficiency Syndrome↗
PubMed1990

A comparison of HIV-1 and HIV-2 infections in hospitalized patients in Abidjan, Côte d'Ivoire.

In late 1988, a cross-sectional study of 1715 adult medical patients hospitalized in Abidjan, Côte d'Ivoire, west Africa, showed an overall prevalence of HIV infection of 46% in men and 28% in women. On the basis of specific testing by whole virus enzyme-linked immunosorbent assay (ELISA), Western blot and synthetic peptide ELISA, HIV-1 infection was found in 25%, HIV-2 infection in 4%, and reactivity to both viruses in 11% of male and female patients combined. People infected with HIV-2, as well as those who were reactive to both HIV-1 and HIV-2, had a frequency of AIDS-associated symptoms and signs similar to that in HIV-1-infected patients, and significantly greater than that in seronegative patients. The significance of dual reactivity, and the natural history and disease spectrum of HIV-2 infection, require further study. Synthetic peptide ELISA is valuable for specific serodiagnosis of HIV-1 and HIV-2 infections. Advanced HIV-2 infection in hospitalized patients in Abidjan is associated with the same symptoms and signs as HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Rapid and specific diagnosis of HIV-1 and HIV-2 infections: an evaluation of testing strategies.

To identify cost-effective testing strategies for HIV-1 and HIV-2 infections, we evaluated different combinations of tests on serum specimens from 1134 consecutive patients attending tuberculosis treatment centers in Abidjan, Côte d'lvoire. Virus-specific whole-virus enzyme-linked immunosorbent assay (WVE), Western blot (WB) and synthetic peptide enzyme-linked immunosorbent assay (SPE) were used in sequential fashion to determine the true prevalence of infection; 27% were reactive to HIV-1, 5% to HIV-2, and 10% to both viruses. Of 239 specimens positive on WB for both HIV-1 and HIV-2, SPE diagnosed 38% as HIV-1-reactive and 16% as HIV-2-reactive, while 46% remained reactive to both viruses. Using WVE or one of two rapid (5-10 min) mixed (HIV-1 and HIV-2) antigen tests (RMATs) as a screening test, followed by SPE as a supplemental test, gave results with sensitivity of 97.3-99.2%, specificity of 99.5-99.7%, and positive predictive value for diagnosing HIV infection of 99.4-99.6%, with important savings in time and reagent costs. SPE allows more specific distinction between HIV-1 and HIV-2 infections than WB, and could replace it as a supplemental test in many settings. WB may be required for specimens reactive on screening tests but negative on SPE, until sensitivity of the SPE is further evaluated. A mixed antigen screening test followed by SPE seems to be an efficient testing strategy for diagnosing HIV-1 and HIV-2 infections.

Blotting, Western↗
PubMed1989

Rapid emergence of AIDS in Abidjan, Ivory Coast.

Between July and November, 1988, 1501 consecutive adult medical admissions to the two largest hospitals in Abidjan, Ivory Coast, were studied. The overall prevalence of infection with human immunodeficiency virus (HIV) types 1 and 2 was 43% in hospital A and 28% in hospital B. AIDS accounted for 19% and 9%, respectively, of medical admissions to the two hospitals, and for 33% of medical deaths in hospital A. The risk of death was significantly higher in HIV-seropositive patients with acquired immunodeficiency syndrome (AIDS) (risk ratio 2.5, 95% confidence interval [CI] 2.0-3.2) and in HIV-positive patients who did not meet the AIDS case-definition (risk ratio 1.7, 95% CI 1.3-2.3) than HIV-negative patients. The male/female ratio of the 265 cases of AIDS identified was 4.8. 50% of patients with AIDS were seropositive for HIV-1 only, 4% for HIV-2 only, and 46% reacted serologically to both viruses. The minimum incidence of AIDS in adult male and female residents of Abidjan (per million per year) is estimated at 1447 and 340 cases, respectively. AIDS in this West African city has emerged as a major public health problem.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Determinants of exercise capacity in hypertrophic cardiomyopathy.

Exercise capacity in hypertrophic cardiomyopathy is thought to relate to elevated left atrial pressure as a consequence of impaired diastolic function, but this assumption has not previously been evaluated. Twenty-three patients with hypertrophic cardiomyopathy underwent hemodynamic assessment during symptom-limited maximal exercise with objective measurement of exercise capacity by respiratory gas analysis. Maximal oxygen consumption and anaerobic threshold were 28.1 +/- 7.5 and 21.5 +/- 6.1 ml/kg per min, respectively (the lower limit of reference range in our laboratory is 39 and 27 ml/kg per min, respectively). Maximal oxygen consumption was reduced in 11 of 13 patients who were in New York Heart Association functional class I and who denied limitation of exercise capacity and in all 10 patients who were in functional class II or III. Maximal oxygen consumption and anaerobic threshold were related to peak cardiac index (r = 0.650, p less than 0.001 and r = 0.459, p = 0.03, respectively) and to the increase in cardiac index on exercise (r = 0.677, p less than 0.001 and r = 0.509, p = 0.016, respectively), but not to cardiac index at rest, peak and rest pulmonary capillary wedge pressure, pulmonary capillary wedge pressure at an oxygen consumption of 15 ml/kg per min or the rise in pulmonary capillary wedge pressure on exercise. These findings are not consistent with the hypothesis that elevated left atrial pressure is the major determinant of exercise capacity in patients with hypertrophic cardiomyopathy and they suggest that, as in patients with chronic cardiac failure, other mechanisms should be considered.

Adult↗