History of Physiology at University of California, Davis.
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Animal Husbandry↗
Biomedical subjects
A H Smith
Publications and source records attributed to A H Smith.
Weight bearing: its lack of effect on fracture healing.
The load transmitted through fresh fractures of the tarsometatarsus of adult chickens was varied by 40% more, or less, than the body weight to determine the effect of load-bearing on fracture healing. The healing fracture was examined for size and strength at 14 days, but no significant differences were detected in any group. The technique was sensitive enough to detect the differences between healing fractures at 7, 10 and 14 days. In this experiment load transmission was not found to be an important factor in fracture healing.
Animals↗
Major colorectal cancer aetiological hypotheses do not explain mortality trends among Maori and non-Maori New Zealanders.
New Zealand colorectal cancer mortality rates are presented for the period 1947-1980. Mortality has been increasing and is now the highest in the world for both males and females in the age range 35-64; indeed New Zealand mortality rates for those aged 35-44 are approximately twice those of other countries with high mortality. By contrast, colorectal cancer mortality rates among Maoris, the indigenous New Zealanders of Polynesian descent, have been decreasing so that they are now less than half the non-Maori mortality rates. These findings cannot be explained by ethnic differences in consumption of the major proposed dietary risk factors: total fat, cholesterol, meat, fibre and beer. Possible differences in the prevalence of lactose malabsorption, in faecal mutagen activity, and in the prevalence of colorectal polyps warrant further investigation.
Adult↗
Mortality among New Zealand Maori and non-Maori Mormons.
Mortality rates for New Zealand Maori and non-Maori Mormons in the period 1970-77 have been compared with those for non-Mormons in the census year 1976 to measure the impact of the Mormon lifestyle on differences in mortality between Maoris and non-Maoris. Maori mortality was much lower among Mormons than non-Mormons suggesting that environmental, rather than genetic factors, play a predominant role in the relatively high overall Maori mortality. However the prevalence of smoking among Maori Mormons was not much lower than for the general Maori population. Reasons for the relative mortality advantage of Maori Mormons were therefore not clear, although attitudes to health and health services utilization, and the influence of strong social support networks, might be involved. Paradoxically, non-Maori Mormon mortality rates were similar to those for non-Mormons. A combination of factors appeared to contribute to this finding including the fact that 26% of non-Maori Mormons were of Pacific Island origin, non-Maori Mormons were of lower socioeconomic status than other non-Maoris, and part Maoris probably constitute a high, but unknown, proportion of Mormons classified as non-Maoris.
Adolescent↗
Malignant lymphoma and multiple myeloma linked with agricultural occupations in a New Zealand Cancer Registry-based study.
Mortality studies have indicated that workers in agriculture and forestry may be at increased risk of developing malignant lymphoma and multiple myeloma. The authors report the findings from a case-control study of 734 male malignant lymphoma and multiple myeloma patients (International Classification of Diseases (ICD) 200-203) registered with the New Zealand Cancer Registry in the period 1977-1981 and aged 20 years or more at time of registration. Controls also were males chosen from the cancer registry with four controls per case, matched on age and year of registration. The case group contained a significant excess of the occupational category involving agriculture and forestry (odds ratio = 1.25, 95% confidence limits = 1.00, 1.56). This excess was almost entirely among those aged less than 65 years at time of registration (odds ratio = 1.45, 95% confidence limits = 1.08, 1.95), particularly among patients with multiple myeloma (ICD 203) (odds ratio = 2.22, 95% confidence limits = 1.31, 3.75) and the category including nodular lymphoma, mycosis fungoides, and unspecified non-Hodgkin's lymphoma (ICD 202) (odds ratio = 1.76, 95% confidence limits = 1.03, 3.02). Mortality from malignant lymphoma and multiple myeloma increased significantly during the period 1955-1979.
Adult↗
Factors associated with psychiatric morbidity in women--a general practice survey.
1517 women between 20 and 59 years of age were screened for current psychiatric disturbance using the General Health Questionnaire, and 382 of the subjects were also interviewed. The women gave information on a variety of family, demographic and reproductive or gynaecological items. Items concerning personal relationships with mother, husband and father were significantly associated with high scores on the GHQ as were demographic items such as marital status, numbers of children and social class and gynaecological items such as sterilization and painful, heavy or irregular periods. The many cross associations between items included in the study need to be considered when interpreting the findings. In particular the highly significant association of relationship and demographic factors with psychiatric morbidity in women must be taken into account when investigating the impact of reproductive physiology and gynaecological procedures on mental health.
Adult↗
Social class, ethnic group, and male mortality in New Zealand, 1974-8.
Social class mortality differences in New Zealand males aged 15 to 64 were investigated for the period 1974-8 using the Registrar-General's classification. The mortality gradient was similar to that previously found in England and Wales, but the New Zealand pattern was non-linear with particularly high mortality in class V. Smoking patterns accounted for much of the increased risk for classes III and IV but did not appear to explain the high mortality in class V. The patterns for the major disease groupings also paralleled those previously found in England and Wales, coronary heart disease and neoplasms displaying weaker gradients than accidents, respiratory diseases, digestive diseases, and infectious diseases. Maori and non-Maori males had comparable social class mortality gradients, but the Maori mortality rates were approximately 50% higher than the non-Maori rates in each class.
Adolescent↗
A standardized benchmark approach to the use of cancer epidemiology data for risk assessment.
Clarity and scientific validity are two criteria for assessing the quality of communications between scientists and risk managers. Regulating permissible exposures on the basis of very-low-dose risk extrapolation uses scientific information that may not meet either criterion. With regard to clarity, it is difficult for an individual to conceive of the meaning of risks on the order of 1 in 1,000,000 lifetime excess. With regard to scientific validity, the uncertainties of extrapolating risks at very low doses are evident in the wide variation in results produced depending on the statistical and pharmacokinetic assumptions made. An alternative approach is to fix benchmarks from which safety factors are chosen (Gaylor, 1983). For epidemiological data, we propose a benchmark of that exposure which would cause 1% cancer excess with 10 yr of exposure followed by 30 yr of further followup. These values have been chosen at this stage of development since they are close to observable values in many cancer epidemiology studies. In the first stage, excess cancer risk versus duration of exposure is plotted and the excess risk is estimated for a exposure duration of 10 yr. The next step involves a short linear extrapolation from the exposure levels linked with this excess risk to the exposure levels that would cause a 1% excess risk over a duration of 10 yr. We have established preliminary benchmarks from published data for benzene and radon daughter exposure. Permissable exposure levels might then be set by deciding on safety factors.(ABSTRACT TRUNCATED AT 250 WORDS)
Carcinogens, Environmental↗
Skeletal mass change as a function of gravitational loading.
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Adipose Tissue↗
Chronic acceleration and egg production in domestic fowl.
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Acceleration↗
Determinants of differences in mortality between New Zealand Maoris and non-Maoris aged 15-64.
Maori mortality is compared with that of other New Zealanders aged 15-64 in the period 1974 to 1978. For males, it is estimated that approximately 20% of the Maori excess in mortality is associated with marked ethnic differences in socio-economic status. Of the remaining excess, an estimated 15% is linked with cigarette smoking, 10% with alcohol consumption (excluding accidental cause of deaths), 5% with obesity and 17% was due to accidents. However 36% of the non-social class related excess involved rheumatic and hypertensive heart disease, nephritis, bronchiectasis, diabetes and tuberculosis which were all associated with a Maori mortality five or more times that for non-Maoris. It is recommended that resources should be allocated so that Maori people can be employed to maintain contact with Maori patients with these diseases in order to improve health services utilisation and compliance with therapy. While it was not possible to determine socio-economic status for females from national mortality data, other findings were similar to those found for males except that mortality from coronary heart disease and cerebrovascular disease also contributed to the Maori excess.
Adolescent↗
Mortality and social class in New Zealand. III: male mortality by ethnic group.
Social class differences in male mortality in New Zealand were investigated separately for Maori, Pacific Island and other New Zealand males aged 15-64. All three groups displayed strong social class mortality gradients but, for each class, the Maori mortality rates were approximately 50% higher than the rates for the "other" category, while the Pacific Islander rates generally occupied an intermediate position. The Maori mortality rates were particularly high for the disease groupings of respiratory diseases, infectious diseases, genito-urinary diseases, endocrine, nutritional and metabolic disorders and diseases of the circulatory system other than coronary heart disease and cerebrovascular disease--even when the data were adjusted for age and social class factors. The Pacific Islander rates were high for the same disease groupings except for endocrine, nutritional and metabolic disorders. Overall, there were substantial social class differences and ethnic differences in mortality and these were largely independent so that only about one-fifth of the Maori mortality excess was attributable to social class factors. Four-fifths of the Maori excess was not attributable to such factors indicating that interventions aimed specifically at lower socio-economic groups will not eliminate the current mortality differences between Maoris and non-Maoris.
Adolescent↗
The therapeutic effect of ascorbic acid and EDTA in manic-depressive psychosis: double-blind comparisons with standard treatments.
The effect of ascorbic acid and ethylene diamine tetra acetic acid (EDTA) in the treatment of manic-depressive psychosis was compared, using double-blind procedures, with recognized treatment regimes. There was no significant difference between the response of depressed patients to amitriptyline or ascorbic acid and EDTA. Manic patients responded significantly better to lithium than to ascorbic acid and EDTA. These results are in keeping with the suggestion that vanadium may be of aetiological importance in depressive psychosis, but do not support such a suggestion for mania.
Amitriptyline↗
Tissue vanadium levels in manic-depressive psychosis.
The vanadium content of hair, whole blood, serum and urine was estimated by neutron activation analysis in samples from manic patients, depressed patients, recovered manic patients, recovered depressed patients and normal controls. The results suggest that manic patients have significantly raised vanadium levels in hair which fall towards control levels with recovery, but there are no significant differences in the mean vanadium content of whole blood or serum. In contrast, depressed patients have raised levels of vanadium in whole blood and serum which appear to fall with recovery. Levels of vanadium in serum correlate strongly with those in whole blood, but neither shows significant correlation with vanadium in hair for either patients or controls. Hair and blood probably serve as indicator tissues for differing aspects of vanadium metabolism.
Adult↗
Tissue densities in developing avian embryos.
Changes in the weight:mass ratio provide the physical basis for the biological responses of terrestrial organisms to alteration in the ambient acceleration field. Where organisms such as aquatic animals occupy dense media, changes in the gravitational environment produce compensating changes in the weight:mass ratios of organism and medium, such that little net load is imposed upon the organism. This relationship also applies to organs of terrestrial animals. Changes in the ambient acceleration field produce compensatory changes in surrounding tissues so that the organ may not develop a significant net load. This relationship has been investigated in the case of the vertebrate brain. However, density gradients within the organ/organism will produce a local gravitational loading, which may lead to biological responses. In fact, a significant density gradient would be an essential character for a gravity receptor. Prenatal development, both in mammals and birds, occurs characteristically in a buoyant condition. In both cases a volume of amniotic fluid develops and surrounds the embryo while it is still of microscopic size. This situation prevails until the latest stages of prenatal development. In mammals the amniotic fluid is lost immediately prior to parturition through rupture of the sac. In chick embryos the amniotic fluid is ingested, beginning on the 13th day with the process being completed by the 18th day of development, just prior to the pre-hatch reorientation of the embryo. Consequently, a net load upon the embryo/fetus is not considered to be a major factor in gravitational experiments of prenatal development. Prenatal development includes marked changes in chemical composition as well as changes in size. This is readily apparent from extensive and detailed examination of the chemical growth for the chick embryo. These chemical materials vary in density, as well as in distribution among the tissues of the developing organism. Consequently, the existence of density gradients, and changes in them may be anticipated during prenatal development.
Albumins↗
Muscularity as a function of species, sex and age in small mammals.
The size of individual skeletal muscles in mammals is well known to change with the degree of mechanical loading imposed on the muscle. Less clear has been the effect of changes in loading of the whole organism on size of the total skeletal musculature. Pitts and coworkers have provided valuable insights by dissection and weighing of the skeletal musculature of animals subjected to various chronic centrifugation, exercise and dietary regimens, and their recent findings are reported at this meeting. However, questions remain. Independently, our laboratory several years ago embarked on a systematic definition of body composition and energy metabolism changes as a function of sex and age in 5 species of small laboratory mammals, the mouse, hamster, rat, guinea pig and rabbit. Six animals of each sex were examined in 8 age cohorts ranging from 1 to 24 months for each of the 5 species.
Aging↗
Soft tissue sarcoma and exposure to phenoxyherbicides and chlorophenols in New Zealand.
Phenoxyherbicides, including (2,4,5-trichlorophenoxy)acetic acid (CAS: 93-76-5), have been widely used in New Zealand for over 30 years. In the light of Swedish studies reporting an association between exposure to phenoxyherbicides or chlorophenols and soft tissue sarcoma, a case-control study was undertaken that involved interviewing 82 subjects (cases) with soft tissue sarcoma and 92 controls with other types of cancer. For those potentially exposed to phenoxyherbicides for more than 1 day not in the 5 years before cancer registration, the estimate of relative risk was 1.3, with 90% confidence limits of 0.6-2.5. The comparable relative risk estimate for chlorophenol exposure was 1.5, with 90% confidence limits of 0.5-4.5. The discovery of cases in trichlorophenol manufacturing plants in the United States lended support to the Swedish findings, but further studies are needed to conclude whether human exposure to these chemicals truly increases the risk of soft tissue sarcoma.
2,4,5-Trichlorophenoxyacetic Acid↗
Elevated vanadium content of hair and mania.
Vanadium content of hair from manic patients, recovered patients, and normal controls was measured by neutron activation analysis. The mean vanadium content of the hair of the manic group was significantly higher than that of the control group and that of the group of recovered manics.
Adult↗