MEDICAL ENGLISH 3
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Heart transplantation...and more
• Perinatal HIV • Hyperlipidemia • Heart transplantation • Male infertility
Perinatal HIV • Hyperlipidemia • Heart transplantation • Male infertility
Is perinatal HIV infection reversible?
The case of an infant who was found to be HIV-positive shortly after birth and who subsequently cleared the virus, raised some questions about perinatally-acquired HIV infection. The child was born in Los Angeles to a woman who had been diagnosed as having asymptomatic HIV-1 infection during the fourth month of . At birth, the child tested negative but at 19 and again at 51 days, HIV-1 was detected in his peripheral blood mononuclear cells. However, at 12 months of age, the child was again seronegative, and numerous subsequent tests over the past 5 years have also been negative, providing evidence of of the virus.An estimated 30 to 40 percent of HIV-infected mothers transmit the virus to their infants, and the majority of the infants will then develop symptoms of AIDS within a few years. Several hypotheses have been put forward to explain this observation, the most of which are the presence of a defective virus or the elimination of the virus by the child’s immune system. At any rate, understanding the mechanism of clearance, whether it is based on the biologic nature of the virus or the immune response of the host, could have implications for HIV-1 therapy and vaccine design.
Lipid-lowering therapy and vasomotor function
Two recent studies in the United States suggest that reduction of serum cholesterol levels can have a beneficial effect on coronary vasomotor activity. The first study coronary endothelial response in 23 patients with atherosclerosis, randomly assigned to receive either lovastatin or placebo. After 12 days of treatment and again after five and a half months, patients received intracoronary of acetylcholine, a known vasoconstrictor. Although the lipid-lowering therapy did not completely normalize the endothelial response to acetylcholine, even after five and a half months, the lovastatin group did have significantly improved responses.In a separate study, 49 patients with coronary artery disease and serum cholesterol levels were randomized to a low-fat diet, to treatment with lovastatin plus cholestyramine or with lovastatin plus probucol, an antioxidant. After one year, the low-fat group had no change in serum LDL cholesterol, while the other two groups had a 40 percent reduction. Moreover, patients in the lovastatin plus probucol group showed a significant improvement in acetylcholine-induced vasoconstriction. These may explain in part the reduced incidence of adverse coronary events known to result from cholesterol-lowering therapy.
Exercise capacity improves in heart-transplant candidates
A recent study involving 107 patients awaiting heart transplant reveals that, in a substantial minority, there is spontaneous improvement and transplantation is no longer necessary. All the subjects, patients on waiting lists for cardiac transplantation, had very poor cardiovascular work capacity as indicated by cardiomyopathy and peak oxygen uptake levels of less than 14 ml/kg/min. 15 of the 107 patients actually underwent transplantation in the next 6 months, and six of them died. Severe angina or hemodynamic deterioration eighteen patients from undergoing repeat exercise testing after six months, but of the 68 patients who did undergo repeat testing, 38 showed a substantial improvement in peak oxygen uptake of 2 ml/kg/min or more. Of those patients who improved, 31 were sufficiently stable for them to be removed from the waiting list for transplantation. These findings show that patient may improve without transplantation and point to the importance of periodical reevaluation of heart-transplant candidates.
Declining Semen Quality and Male infertility
A study among fertile men in France has found a significant decline in the quality of semen over the past 20 years. Data collected on semen donated to a sperm bank in the Paris area indicate that, if semen volume has remained constant, the concentration and motility have fallen. The authors the hypothesis that the decline may be due to impaired spermatogenesis and seek to establish a between declining sperm quality and a possible rise in the incidence of abnormalities of the male genital tract, including cryptorchidism. The suggestion that these phenomena share a common geographical area may point to a common origin, in environmental factors or in to fertility drugs including estrogen. Although these results seem to corroborate findings in other countries, the question remains whether sperm donors are representative of the general public and whether a single sample per donor is . Moreover, differences in donor age and in the duration of abstinence prior to donation should give cause for caution, particularly because, despite the decline in sperm concentrations, there is little evidence that male infertility is .
The case of an infant who was found to be HIV-positive shortly after birth and who subsequently cleared the virus, raised some intriguing questions about perinatally-acquired HIV infection. The child was born in Los Angeles to a woman who had been diagnosed as having asymptomatic HIV-1 infection during the fourth month of pregnancy. At birth, the child tested negative but at 19 and again at 51 days, HIV-1 was detected in his peripheral blood mononuclear cells. However, at 12 months of age, the child was again seronegative, and numerous subsequent tests over the past 5 years have also been negative, providing evidence of clearance of the virus.An estimated 30 to 40 percent of HIV-infected mothers transmit the virus to their infants, and the majority of the infants will then go on to develop symptoms of AIDS within a few years. Several hypotheses have been put forward to explain this observation, the most plausible of which are the presence of a defective virus or the elimination of the virus by the child’s immune system. At any rate, understanding the mechanism of clearance, whether it is based on the biologic nature of the virus or the immune response of the host, could have profound implications for HIV-1 therapy and vaccine design.
Two recent studies in the United States suggest that reduction of serum cholesterol levels can have a beneficial effect on coronary vasomotor activity. The first study assessed coronary endothelial response in 23 patients with atherosclerosis, randomly assigned to receive either lovastatin or placebo. After 12 days of treatment and again after five and a half months, patients received intracoronary infusions of acetylcholine, a known vasoconstrictor. Although the lipid-lowering therapy did not completely normalize the endothelial response to acetylcholine, even after five and a half months, the lovastatin group did have significantly improved responses.In a separate study, 49 patients with coronary artery disease and elevated serum cholesterol levels were randomized to a low-fat diet, to treatment with lovastatin plus cholestyramine or with lovastatin plus probucol, an antioxidant. After one year, the low-fat diet group had no change in serum LDL cholesterol, while the other two groups had a 40 percent reduction. Moreover, patients in the lovastatin plus probucol group showed a significant improvement in acetylcholine-induced vasoconstriction. These findings may explain in part the reduced incidence of adverse coronary events known to result from cholesterol-lowering therapy.
A recent cohort study involving 107 patients awaiting heart transplant reveals that, in a substantial minority, there is spontaneous improvement and transplantation is no longer necessary. All the subjects, ambulatory patients on waiting lists for cardiac transplantation, had very poor cardiovascular work capacity as indicated by cardiomyopathy and peak oxygen uptake levels of less than 14 ml/kg/min. 15 of the 107 patients actually underwent transplantation in the next 6 months, and six of them died. Severe angina or hemodynamic deterioration precluded eighteen patients from undergoing repeat exercise testing after six months, but of the 68 patients who did undergo repeat testing, 38 showed a substantial improvement in peak oxygen uptake of 2 ml/kg/min or more. Of those patients who improved, 31 were sufficiently stable for them to be removed from the waiting list for transplantation. These findings show that patient outcome may improve without transplantation and point to the importance of periodical reevaluation of heart-transplant candidates.
A retrospective study among fertile men in France has found a significant decline in the quality of semen over the past 20 years. Data collected on semen donated to a sperm bank in the Paris area indicate that, if semen volume has remained constant, the concentration and motility have fallen. The authors put forward the hypothesis that the decline may be due to impaired spermatogenesis and seek to establish a link between declining sperm quality and a possible rise in the incidence of abnormalities of the male genital tract, including cryptorchidism. The suggestion that these phenomena share a common geographical area may point to a common origin, in environmental factors or in exposure to fertility drugs including estrogen. Although these results seem to corroborate findings in other countries, the question remains whether sperm donors are representative of the general public and whether a single sample per donor is reliable. Moreover, differences in donor age and in the duration of abstinence prior to donation should give cause for caution, particularly because, despite the decline in sperm concentrations, there is little evidence that male infertility is on the rise.
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