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Biomedical subjects

C Tanner

Publications and source records attributed to C Tanner.

33 records · Page 2Linked to original sources
PubMed1990

Environmental risk factors in Parkinson's disease.

To investigate possible risk factors for Parkinson's disease (PD) we conducted a case-control study of 150 PD patients and 150 age- and sex-matched controls. We interviewed and examined all 300 subjects. We collected demographic data including lifetime histories of places of residence, source of drinking water, and occupations such as farming. Subjects completed a detailed questionnaire regarding herbicide/pesticide exposure. Rural living and drinking well water were significantly increased in the PD patients. This was observed regardless of age at disease onset. Drinking well water was dependent on rural living. There were no significant differences between cases and controls for farming or any measure of exposure to herbicides or pesticides. These data provide further evidence that an environmental toxin could be involved in the etiology of PD.

Aged↗
PubMed1984

Biophysics of domes formed by the renal cell line Madin-Darby canine kidney.

When cultured on an impermeable substratum, the renal epithelial cell line Madin-Darby canine kidney (MDCK) forms domes. From a knowledge of dome shape, radius, and hydrostatic pressure difference delta P, from within to outside the domes, biophysical properties of the epithelium can be determined. By microscopy, circular based domes were found to be section of spheres with a constant height-to-radius ratio h/r of 0.684. By using the Laplace equation derived for this geometry and measurements of delta P and r, the values of the tension of cell dish adhesion Ta and dome wall tension Tw were found to be constants of 6.60 and 7.08 torr, respectively. By combining constants, Ta, and h/r, and because domes are section of spheres, delta P and dome volume were shown to be known functions of radius alone. The modulus of elasticity of the epithelium was calculated to be 4.82 X 10(3) dyn/cm2.

Animals↗
PubMed1983

Transepithelial transport in cell culture. A theoretical and experimental analysis of the biophysical properties of domes.

Dissociated cells of transporting epithelia, when cultured on an impermeant substratum, form polarized monolayers frequently characterized by the presence of domes. If the assumption is made that the monolayer exhibits a uniform stretch modulus of elasticity and tension of cell-dish adhesion, Ta, then biophysical properties of the epithelium can be predicted. We have shown that for such epithelia, domes should (a) have circular bases, (b) be sections of spheres with a constant height to radius, h/r, ratio, (c) have a dome-wall tension, Tw, that is constant, and (d) have a dome volume that is a function of radius alone. Additionally, a Laplace equation derived for this geometry predicted the hydrostatic pressure from within to outside domes as a decreasing function of radius alone. By microscopy, domes had predominantly circular bases and were found to be sections of spheres with a constant height, h, to radius, r, ratio of 0.684. Using the Laplace equation derived for this geometry and measurements of delta P and r, the tension of cell-dish adhesion, Ta, and dome-wall tension, Tw, were found to be constants of 6.60 and 7.08 torr, respectively. Combining the constants for Ta and h/r ratio, and the fact that domes are sections of spheres, delta P and dome volume were shown to be known functions of radius alone. In addition, the modulus of elasticity of the epithelium was calculated to be 4.82 X 10(3) dyn/cm2.

Animals↗
PubMed1978

Australia's potentially most venomous snake: Parademansia microlepidotus.

Studies on the venom of the small-scaled or fierce snake, Parademansia microlepidotus, suggested that its combination of high toxicity and relatively large venom yield make it the most venomous snake in Australia. The species is distinct from the taipan, but its venom is neutralized by taipan antivenom but not other monospecific antivenoms.

Antivenins↗
PubMedDate not supplied

Studies on the venom of Oxyuranus microlepidotus.

The Australian Small-scaled Snake, Oxyuranus microlepidotus , recently rediscovered, is the world's most venomous snake, with a murine LD50 of 0.01 mg/kg. Recently developed immunological techniques, combined with a whole animal model, have enabled us to measure accurately the mass of venom actually injected by a striking snake. The venom of this species contains at least six identified protein fractions, and one or more of these possesses potent neurotoxic action. An initial assessment of the molecular weights of each of these is reported. This study describes field biting experiments applicable to potential human snake-bite, and presents data concerning the injected venom:LD50 ratio which is an index of potential human lethality. This snake delivers an average mass of 17.3 mg in a strike, and the injected mass:LD50 ratio is 1730, the highest recorded for any snake. Comparative results for five other Elapidae whose venom contains potent neurotoxins are also presented. An average mass of 0.6 mg of venom is split on the skin surface during a strike, and 40% of this can be recovered within three hours after a simulated bite. As with other Elapidae studied to date, an adequate mass of venom remains on the skin for an accurate species diagnosis to be made in the case of human snake-bite.

Animals↗
PubMedDate not supplied

Measurement of Type A behavior in preschoolers.

The purpose of this study was to investigate the psychometric properties of the Matthews Youth Test of Health (MYTH) and its subscales of Hostility, Competitiveness, Impatience, and Leadership when used with preschoolers. The MYTH was completed by 13 teachers on 155 preschool children in a cross-sectional study and on sub-samples of this original group who were followed during a 2-year longitudinal study. These results were used to investigate internal consistency and test-retest reliability of the MYTH. Construct validity was evaluated by factor analysis as well as by examining the relationship of the MYTH scale and its subscales to cardiovascular reactivity, self-esteem, and locus of control. Construct validity was further assessed by testing for a predicted difference between boys and girls on the MYTH.

Blood Pressure↗
PubMedDate not supplied

Type A behavior and cardiovascular responsivity in preschoolers.

Type A behavior was investigated in preschool children in relation to cardiovascular reactivity. One hundred forty-four children from 3 1/2 to 6 1/2 years of age were categorized by their teachers according to the Matthews Youth Test for Health as Type A, Mixed, or Type B. The children's pulse, pulse rate variability, and blood pressure were then measured at rest and during a challenging situation. Analysis of covariance indicated that Type A children showed a significantly greater systolic rise to challenge than did Type B children, a finding similar to that of Type A adults, college students, and adolescents.

Blood Pressure↗