Biomedical subjects
Publications and source records attributed to A Chang.
A survey of health services in a group of licensed day care centers indicates a general lack of written guidelines, failure to have a designated health coordinator and a serious paucity of nutrition and dental education programs.
A fetal intensive care unit was formed at the Queen Victoria Memorial Hospital in 1972. Because of some doubt concerning the value of fetal intensive care, a controlled clinical trial including all high-risk patients was performed. The trial clearly showed that intensive care is associated with improved neurologic and biochemical status of the neonate; however, it is possible that this improvement results from the use of fetal diagnostic tests or some other factor associated with intensive care. Sufficient evidence was gathered to warrant the continuation of fetal intensive care in this hospital, but in other contries, where funding is difficult to obtain, a controlled trial would appear justified.
This paper presents the results of measurements of the acid-base and gaseous status of maternal and fetal capillary blood at the time of amniotomy, before the onset of labor. The correlation coefficient between maternal and fetal bicarbonate concentration is 0.6, and that between maternal and fetal PCO2 is 0.31. From the results obtained, as well as from a survey of other work in the field, it is proposed that the diffusion of carbon dioxide across the placenta could not explain some of the findings and that bicarbonate concentrations equilibrate across the placenta.
In the control trials on near-term pregnant women before the onset of labour, nalorphine was found to cause a mild respiratory acidosis in the mother and metabolic acidosis in the fetus. These effects were not apparent when naloxone was administered.
Spermatozoa migrate rapidly into a diluent brought into contact with semen. When this process was used to collect sperm in a diluent contained in Pasteur pipettes that were dipped into semen for 1 hour, concentrations of spermatozoa ranging from 0.6 to 5.7 X 10(6) cells/ml were obtained. This method yielded sperm suspensions free of seminal plasma and populations of spermatozoa that had increased motility ratings compared with the original semen. In contrast, removal of the seminal plasma by a procedure involving three dilutions and two gentle centrifugations resulted in a decrease in the average motility ratings. Determinations were made of the electrolyte, energy substrate, and trace element content of preovulatory human tubal fluid. A sperm diluent having an electrolyte composition similar to that of tubal fluid was formulated and used for collecting spermatozoa. Population of spermatozoa that migrated from semen into this diluent had significantly greater mean velocities than sperm in the semen. Moreover, the diluent proved to be a favourable medium for significantly delaying the deterioration of sperm progression over a 24-hour period.
This paper describes the 13-year experience of one school of public health in preparing physicians for the field of maternal and child health. Some 256 (87.7 percent) of the 292 graduates have remained in community health work. Of the 292 graduates, 106 (36.3 percent) are engaged in some teaching responsibilities.
Earlier results indicating that vaccinia virus entered L cells by a process of direct fusion between the virus envelope and the plasma membrane of the cell have been confirmed and extended using immuno-ferritin conjugates to locate virus antigens on the host cell surface. After fusion, components of the virus envelope become rapidly dispersed in the plasma membrane. Fusion has also been observed as the predominant mode of entry of vaccinia virus into HeLa cells.
This paper reports two randomized control trials on the effects of nalorphine, pethidine, morphine and heroin on fetal and maternal acid base status. The drugs decreased pH and increased pCO2 in the mother, and decreased pH and base excess in the fetus. The changes in the fetus were independent of the changes in the mother. In equivalent dosages, nalorphine increased maternal pCO2 more than pethidine and morphine. The effects of heroin were found to be greater than that of other drugs, and we suggest that heroin should be avoided where the fetus is already at risk.
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A progressive fetal respiratory acidosis occurs in the second stage of labour. A double-blind controlled trial showed that the intravenous infusion of Ritodrine abolished this.
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