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Biomedical subjects

M Hatch

Publications and source records attributed to M Hatch.

15 recordsLinked to original sources
PubMed1992

Childhood leukemia around nuclear facilities.

Epidemiologic studies on the health effects of living near nuclear facilities have been rare and, indeed, radiobiological models would not predict any detectable increase in cancer risk to the general public from the very low levels of radioactivity emitted by nuclear installations. Thus the recent evidence suggesting an excess of childhood leukemias in the vicinity of certain nuclear sites in the United Kingdom has generated considerable controversy. To help resolve the uncertainty and enhance interpretability of results, future epidemiologic studies will need to be designed with great care (and within realistic cost limits). This commentary suggests three areas for methodologic consideration: (i) definition and modelling of radiation exposure; (ii) selection of cancer sites and sensitive subgroups; and (iii) use of incidence or mortality data. Specific suggestions for further epidemiologic research are offered as well.

Adolescent↗
PubMed1992

The epidemiology of electric and magnetic field exposures in the power frequency range and reproductive outcomes.

Some laboratory studies have reported effects of extremely low frequency electric and magnetic fields on calcium homeostasis and pineal gland function which potentially could have consequences for reproductive health. The purpose of this review is to report results of research to date in humans on maternal, paternal and fetal exposure to the 50-60 Hz fields associated with electricity, and to propose populations, endpoints and strategies for future research.

Adult↗
PubMed1991

The effects of Carbogen, carbon dioxide, and oxygen on noise-induced hearing loss.

An investigation into the effect of Carbogen (95% O2/5% CO2), 5% CO2/air, and 100% oxygen on cochlear threshold shifts caused by noise was undertaken. Five groups of eight pigmented guinea pigs were exposed to 105 dB broad band noise for 6 h per day for five consecutive days with each group receiving the various gaseous mixtures either during noise exposure or for 1 h immediately after noise exposure. A control group received the same noise exposure but respired air. Auditory threshold shifts, as measured by the auditory evoked brainstem response, were measured at 2,4,8,12,16, 20 and 24 kHz. Recordings were taken pre-exposure and at Day 1, 3, 5, and Weeks 2 and 3 after noise exposure. Carbogen, given during noise exposure, resulted in a trend toward less post noise exposure threshold shift (as compared to controls) which reached statistical significance by Week 3 at all frequencies except 2 and 20 kHz. Subjects given Carbogen after exposure also showed a general trend toward decreased noise induced threshold shifts, as compared to controls, but this was not statistically significant. The mixture of 5% CO2/air given during noise exposure yielded no difference in threshold shifts as compared to controls. When 100% oxygen was administered during noise exposure, a marked decrease in noise induced threshold shifts could be seen as compared to controls, with differences reaching statistical significance by day 5 at most frequencies. These results indicate that oxygen (i.e. cochlear-oxygenation) is a more important factor than CO2 (i.e., as a vasodilator) in protection of the cochlea from noise induced damage.

Animals↗
PubMed1991

A retrospective analysis of the metabolic status of stone formers in the New York City metropolitan areas.

Eighty stone-forming patients were evaluated as outpatients for risk factors involved in stone formation. Analyses of the major stone risk parameters in the 24-hour collections indicated low volume (less than 2L) in about 79% of these patients. Forty percent of all patients were found to be hypocitraturic, 30% were hyperoxaluric, 18% were hypercalciuric, and 13% were hyperuricosuric. Sixty-one percent of the patients had a normal calcium load study; of these, four patients were uric acid stone formers. The remaining 39% of patients were classified as either absorptive hypercalciuric (16 patients), or fasting hypercalciuric with normal (12 patients) or elevated (3 patients) serum parathyroid hormone (PTH) levels. Of these 31 patients, 61% were not hypercalciuric on the basis of the 24-hour urine collections. The protocol provided a diagnosis in over 98% of patients. Low urinary volume was the only defect found in 5% of patients, while more than one risk factor was identified in 93%.

Adult↗
PubMed1990

Paternal age and trisomy among spontaneous abortions.

The relationship of paternal age to specific types of trisomy and to chromosomally normal loss was investigated in data drawn from a case-control study of spontaneous abortions. Differences in paternal age between karyotype groups and controls delivering after 28 weeks gestation were tested using an urn model analysis which adjusted, by regression, for maternal age and, by stratification, for the effects of design variables (payment status, phase of study) and demographic factors (language, ethnicity). The magnitude of paternal age differences was estimated using least squares regression analysis. For chromosomally normal cases there was no association with paternal age. Among the fourteen trisomy categories examined, four (7, 9, 18, 21) showed increased paternal age (greater than or equal to 1 year above expectation), three (13, 20, 22) showed decreased paternal age and the rest, including the most common, trisomy 16, showed negligible differences. Only the association with trisomy 22 was statistically significant (P = 0.012), with a predicted reduction in paternal age of 2.1 years (95% CI -4.9, -0.5 years). This association did not vary with maternal age, payment status, phase of study, language or ethnicity. Because previous observations are extensive, the relation of paternal age to trisomy 21 was examined further. The overall association was not significant (beta = 0.8 years; 95% CI -0.8, 2.4 years). Moreover, there was evidence that the magnitude and direction of paternal age associations vary significantly within the sample, although not between subgroups defined on the basis of payment, phase of study, language or ethnicity. With respect to maternal age, the trend is towards a greater paternal age difference for trisomy 21 losses in younger women (P = 0.058). Given the number of tests performed, the finding for trisomy 22 and reduced paternal age could be due to chance. Among trisomy types, the direction of paternal age associations was not consistent for chromosomes grouped according to characteristics that might relate to the probability of nondisjunction, such as size, arm ratio, or nucleolar organizer region content, or to the potential viability of the trisomy. Thus, neither on statistical nor biological grounds do the data provide compelling evidence of paternal age effects on the trisomies found among spontaneous abortions, or on chromosomally normal losses.

Abortion, Spontaneous↗
PubMed1990

Background gamma radiation and childhood cancers within ten miles of a US nuclear plant.

In light of some recent reports concerning childhood leukaemia near nuclear installations, we examined rates of cancer in children in relation to background gamma ray exposure. Data from a national monitoring programme around nuclear facilities were used to map the distribution of background gamma radiation for 69 small geographical subunits (average population 2300) within ten miles of one US nuclear plant. An association was found for incidence of childhood cancers as a whole (odds ratio (OR) = 2.4; 95% confidence limits (CL) 1.2, 4.6). For leukaemias specifically, the odds ratio was also elevated but confidence limits were very wide (OR = 2.4; 95% CL 0.5, 12.9). Analyses adjusting for sociodemographic characteristics of study tracts (population density and income) gave similar results; data on other risk factors were unavailable. Conventional risk models would not predict a detectable increase in childhood cancer from background gamma radiation, particularly not an increase of this magnitude. The large effect for solid tumours as well as leukaemias is also somewhat counter to expectation. Since a priori the association we observed was unlikely, it is important to know if similar trends in childhood cancer with background radiation are seen in other areas before rejecting chance or bias as an explanation for the result.

Accidents↗
PubMed1976

An enzymic method for the spectrophotometric determination of oxalic acid.

A simple method is described for the measurement of urinary oxalate. Oxalate decarboxylase is coupled with NAD+ requiring formate dehydrogenase and the result recorded spectrophotometrically. Accurate determination can be carried out either on urine or a citrate extract or urine. Using the citrate extract procedure, the urinary samples can be stored for at least 3 months without any effect on the oxalate content.

Oxalates↗