Biomedical subjects

M A Zive

Publications and source records attributed to M A Zive.

3 recordsLinked to original sources

PubMed1990

Nitrous oxide and infertility.

Our laboratory has reported changes in luteinizing hormone releasing hormone (LHRH) from the hypothalamus following nitrous oxide (N2O) exposure. LHRH augments LH release, which in turn causes ovulation. This study evaluated how N2O disrupts ovulation and the possible resulting infertility. Adult virgin female rats (N = 64) were housed with a 12 h:12 h light cycle. Daily vaginal smears were taken and only rats exhibiting two consecutive normal 4-day ovulatory cycles were used. Thirty-two rats were placed in an environmental chamber and exposed to a mix of hydrated 30% N2O and compressed air delivered at 1.6 L/min for 8 h/day for 4 days (one cycle); controls received compressed air. All rats exposed to N2O exhibited disrupted cycles following the first day of the 4-day exposure. From a group of 12 N2O-exposed rats, 11 went into constant proestrus (day of ovulatory surge) for up to 3 weeks. Control rats cycled normally. Following each exposure, eight rats were perfused, brains sectioned, and LHRH cells identified by immunocytochemistry. Eight control rats also underwent this procedure. A threefold increase in LHRH cells was noted in N2O rats. In addition, 12 rats received 30% N2O for 4 days, followed by mating with proven male breeders for 4 days, as were controls. Six of 12 N2O rats and 12 of 12 control rats gave birth. Contrary to previous reports, no significant difference was noted in litter size or weight. The constant proestrus seen after N2O exposure is due to disruption of LHRH cells in the hypothalamus (blocked LHRH release). It is this disruption of LHRH, and therefore ovulation, which results in infertility.

Animals↗

PubMed1987

A new wrinkle to the earlobe crease.

Several studies had indicated that the earlobe crease may be a marker of coronary artery disease (CAD). This prospective study of 261 consecutive men undergoing coronary arteriography was carried out to evaluate the association of the earlobe crease with the presence and extent of CAD. A positive earlobe crease was detected in 67% of this population. When examining the presence of CAD in men with (n = 175) and without (n = 86) an earlobe crease, 85% of those with and 85% of those without an earlobe crease showed some degree of CAD. Since the prevalence of an earlobe crease increased with advancing age, we examined the age-specific prevalence rates of CAD in men with and without an earlobe crease and found no significant differences in those rates. A similar lack of association between earlobe crease and CAD was seen when we simultaneously controlled for other potentially confounding factors. We conclude that the reported association between earlobe crease and CAD is due to the fact that the prevalence of earlobe crease and CAD each increase with age.

Aged↗

PubMedDate not supplied

Nitrous oxide and occupational exposure: it's time to stop laughing.

Although nitrous oxide (N(2)O) has been widely used since 1844, in recent years it has been implicated in a number of serious health hazards such as reproductive, nerve, liver, and kidney disorders. The National Institute of Safety and Health (NIOSH) recommends a limit of 25 ppm for chronic exposure to N(2)O in the dental office. Our study monitored ambient N(2)O levels in the dental office. N(2)O levels were compared for procedures performed in open clinics and private operatories as well as with and without a gas-scavenging system. Measurements were taken in the Dental Breathing Zone (DBZ) and Dental Chair Foot (DCF) at regular intervals. A four- to eightfold increase in average N(2)O levels was noted in the DBZ for unscavenged versus scavenged procedures. A three- to fourfold increase for unscavenged versus scavenged procedures was similarly noted in the DCF. N(2)O were significantly higher in private operatories than in open clinics, due to limited room volumes and in the DBZ over the DCF, due to mask leakage and increased oral exhalation. Scavenged N(2)O levels for both operatory types did not meet NIOSH guidelines. In contrast to previous studies using any form of gas removal, our study shows a significant decrease in N(2)O level achieved with an adequate scavenger system. With only four states regulating the use of N(2)O, and with concern over its deleterious effects growing, additional states and the federal government are expected to enact legislation regulating the use of N(2)O in the near future.

Air Pollutants, Occupational↗