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Biomedical subjects

K R Cooke

Publications and source records attributed to K R Cooke.

51 records · Page 3Linked to original sources
PubMed1985

Migration and death from malignant melanoma.

The age-standardized mortality rates for malignant melanoma of the skin in immigrants to New Zealand were compared with those of New Zealand-born non-Maoris. Immigrants from European countries had mortality rates that were generally similar to those prevailing in their countries of origin, although, among immigrants from the British Isles, early age at migration was associated with a mortality rate similar to that of New Zealand-born non-Maoris. In a community survey, British immigrants were not less likely to have had severe sunburn, but had fewer moles, than New Zealand-born non-Maoris. The lower melanoma mortality, and the effect of age at migration, could be mediated by differences in mole frequency.

Adolescent↗
PubMed1985

Frequency of moles in a defined population.

The occurrence of moles was studied in a community survey of 872 adults, using criteria that allowed comparison with two earlier surveys. Men and women had similar numbers of moles-on average, 15 moles of diameter 2 mm or greater, and 39 moles of all sizes. The frequency of moles declined with age and varied according to body site. Comparison of the findings with those of previous surveys-in New York in about 1950 and in Sydney in about 1970-suggested that the frequency of moles has increased as malignant melanoma has become more common. Little is known about the epidemiology of moles, which may hold the key to the explanation of the rising incidence of melanoma in many countries.

Adult↗
PubMed1984

Socio-economic status, indoor and outdoor work, and malignant melanoma.

Among New Zealand non-Maori men, professional, technical, administrative and managerial workers had the highest incidence and mortality rates for malignant melanoma of the skin; labourers and workers in production and transport had the lowest rates. Reclassification of occupations, in terms of both socio-economic status and a three-step scale of outdoor exposure during work, suggested that differences between occupational groups were determined by differences in socio-economic status. Outdoor work exposure seemed to have little effect on the risk of melanoma.

Adult↗
PubMed1984

Effects of medium acetate on cellular volume in rabbit renal cortical slices.

Slices of rabbit renal cortex were incubated at 25 degrees C in media in which acetate replaced chloride. There was gross cellular swelling in isosmotic 132 mM-acetate medium, and this swelling was unique in that, with a normal medium potassium concentration, it was accompanied by a substantial increase in cellular potassium content. This accumulation of potassium, but not the cellular swelling, was dependent upon metabolism and inhibited by ouabain. This accumulation of potassium was not dependent upon the cellular swelling. It also occurred in a hyperosmotic acetate medium in which swelling was minimized. In isosmotic media, the cellular swelling was proportional to medium acetate concentration and was also affected markedly by medium pH, being greatest at an initial medium pH of 7.1 and least at pH 7.7. The swelling was reversed and cellular composition restored when tissue was re-incubated in NaCl medium. Ouabain (10(-3)M) largely prevented this recovery in volume. The results are consistent with plasma-membrane-based theories, on the assumption that membranes are much more permeable to undissociated acetic acid than they are to the acetate ion. They are inconsistent with the expectations of an alternative hypothesis (the association--induction hypothesis) which ascribes the maintenance of cellular composition to properties of cellular proteins and cellular water rather than to those of the plasma membrane. The results do not favour the suggestion that cellular swelling itself results in irreversible cellular damage. The results are consistent with the hypothesis that the ouabain-inhibitable Na-K-ATPase plays a major role in the regulation of cellular volume. No alternative metabolically dependent volume regulating mechanism need be postulated to explain them.

Acetates↗
PubMed1983

Trends in malignant melanoma of skin in New Zealand.

Incidence and mortality rates for malignant melanoma of skin in the New Zealand non-Maori population over the past 30 years were analysed in relation to sex, age, birth cohort and time. In both sexes, the age-standardized incidence rates increased approximately exponentially with time, with an annual increment of 7.5%. The age-standardized mortality rates increased approximately linearly with time, resulting in a two- to three-fold increase over 30 years, as compared with an eight- to nine-fold increase in the incidence rates. Descriptive birth cohort analysis shows different patterns of increase for incidence and mortality rates. The main difference is that, whereas incidence rates have continued to increase in recent birth cohorts, mortality rates have stabilized. The explanation for this difference is uncertain.

Adolescent↗
PubMed1981

Ouabain and regulation of cellular volume in slices of mammalian renal cortex.

1. The effect of ouabain on cellular volume recovery in rabbit, guinea-pig and rat renal cortical slices was studied. A concentration of ouabain that is maximally effective in inhibiting slice potassium accumulation was determined for each species. Slices from each species were either freshly prepared and then incubated, or leached and then incubated, or preincubated in oxygenated ordinary medium (equilibrated), leached and then reincubated in media with and without this concentration of ouabain. All incubations were at 25 degrees C.2. Potassium loss produced by ouabain was greater in rabbit and guinea-pig slices than in rat slices.3. With slices that were freshly prepared and then incubated, and with slices that were leached and then incubated, cellular volume recovery was inhibited by ouabain in rabbit and guinea-pig slices, but not in rat slices.4. After equilibration, swelling during leaching was less, especially in rabbit and guinea-pig slices. However, on subsequent reincubation, significant differences in tissue water and cation contents that were consistent with inhibition of cellular volume recovery by ouabain, were seen in slices from these two species, but not in rat slices.5. Slices from all three species, when incubated with concentrations of ouabain that were maximally effective in inhibiting potassium accumulation, appeared to approach a steady-state tissue potassium content that was greatest in rat slices and least in rabbit slices. Rat slices, previously depleted of potassium, reaccumulated potassium in the presence of 10 mm-ouabain to reach this steady-state potassium content.6. Despite superficial appearance to the contrary (especially in the case of rat slices) these results are consistent with a major role for the conventional pump in controlling cortical cell volume. They do not provide evidence for the postulate that renal cortical cells possess a separate, ouabain-insensitive mechanism regulating cell volume.

Animals↗
PubMed1979

Oxygen consumptions and potassium contents of slices of rat renal cortex.

An oxygen electrode respirometer for determining the oxygen consumption of slices of mammalian renal cortex is described and assessed. Though rat renal cortical slices incubated in potassium-free medium for one hour lost 102 +/- 14 mmol of potassium/kg dry weight, there was only a small, nonsignificant fall in oxygen consumption. In contrast the oxygen consumption of slices incubated in potassium-free medium with 10 mmol.1-1 ouabain was markedly reduced (by 32 +/- 6%), while such slices lost 180 +/- 15 mmol of potassium/kg dry weight. These disproportionate effects on potassium loss and inhibition of oxygen consumption suggest that in renal cortical slices the loss of potassium in low potassium medium is not primarily due to inhibition of the conventional sodium pump.

Animals↗
PubMed1978

Ouabain and regulation of cellular volume in freshly prepared slices of rabbit renal cortex.

1. Changes in the water and ion contents of rabbit renal cortical slices, which had been bathed, immediately after slicing, in air-equilibrated media at room temperature ('freshly prepared slices'), were followed during subsequent incubation at 25 degrees C in oxygenated media of the same composition as the initial bathing medium. 2. In comparison with conventional 'equilibrated' slices (slices incubated at 25 degrees C in oxygenated ordinary medium immediately after slicing) these 'freshly prepared' slices had increased tissue water, sodium and chloride contents and low tissue potassium contents. 3. Control freshly prepared slices incubated at 25 degrees C in oxygenated ordinary medium recovered within 4 min to the tissue water content that is usual for rabbit renal cortical slices incubated in oxygenated ordinary medium at 25 degrees C. Freshly prepared slices incubated at 25 degrees C in oxygenated media containing 1 mM-oubain took 75 min or more to recover to this usual tissue water content. Thus the presence of 1 mM-oubain in both bathing and incubation media produced a marked inhibition of the volume recovery observed when freshly prepared slices are incubated in oxygenated media at 25 degrees C. 4. Reduction of the ouabain concentration reduced the inhibition of cell volume recovery. 5. Replacement of medium glucose by 3-O-methylglucose did not inhibit cell volume recovery in the absence of ouabain. 6. The oxygen consumptions of slices that were bathed and incubated in 1 mM-ouabain media were similar to those of slices initially bathed and incubated in ouabain-free media and then incubated in ouabain media. Thus the effect of ouabain in inhibiting cell volume recovery was unlikely to be secondary to inhibition of cellular energy production. 7. The tissue potassium content of slices incubated aerobically in 1 or 10 mM ouabin fell to an apparently stable value of approximately 100 m-mole/kg dry wt., which corresponds to a calculated concentration ratio of 10:1 across the cellular membrane, suggesting that some residual potassium uptake may still have been occurring. 8. These results indicate that in freshly prepared rabbit renal cortical slices ouabain-sensitive mechanisms play a major role in cell volume recovery. They are not in accord with the postulate that renal cortical cells possess a separate ouabain-insensitive mechanism regulating cell volume.

Animals↗
PubMed1978

Effects of ouabain and potassium-free media on cellular volume regulation in rat renal cortical slices.

1. Changes in water and ion contents of rat renal cortical slices were followed over 4 hr incubation at 25 degrees C in potassium-free media and media with ouabain. Slices that lost potassium more rapidly swelled earlier. 2. Greater swelling with lower tissue potassium contents was also observed in slices preincubated and leached in potassium-depleting media and in slices incubated in lithium medium with 10 mM-ouabain and in potassium-free lithium medium with 10 mM-ouabain. 3. This swelling associated with potassium depletion was also observed when slices were incuabted in media where the substrate was malate in place of glucose. 4. No distinct fall in the oxygen consumption of potassium-depleted slices was detected during the period in which slices commenced swelling. 5. These results suggest that the swelling observed in potassium-depleted rat renal cortical slices is unlikely to be secondary to inhibition of cellular energy production.

Animals↗
PubMed1976

Effect of the CO-2-bicarbonate buffer system on the water and ion contents of rat renal cortical slices.

(1) Partial replacement of medium chloride by bicarbonate, with pHmaintained constant by addition of CO2, lead to a greater rate of swelling when rat renal corti cal slices were leached in nitrogenated medium at 0--2 degree C. This greater rate of swelling was still present when 1 mM iodoacetate was added to the leaching media. (2) Rat renal cortical slices incubated in oxygenated bicarbonate medium at 25 degree C maintained a slightly greater tissue water content than did slices incubated in phosphate-buffered media. Inclusion of malate in the incubation medium also led to a greater steady-state water content when slices were incubated at 25 degree C in oxygenated media. These results suggest that that particular cell volume which is maintained by metabolism and the double Donnan system is determined at least in part by the nature of the extracellular anions. (3) The rates of net sodium extrusion and of net potassium uptake were not significantly altered by presence of CI2 and bicarbonate in the incubation medium.

Animals↗
PubMedDate not supplied

An evaluation of the mobility allowance for families with handicapped children.

A variety of methods were used to evaluate the mobility allowance as a social security benefit for families with handicapped children. A study of the policy development showed that the mobility allowance was not the outcome of a rationally-planned and coherent strategy designed to meet need. A survey of families with a child beneficiary showed that the allowance helped to sustain the child's existing mobility, but did little to increase it. A study of the criteria according to which the allowance is allocated suggested that there is a case to be made for paying the allowance from the age of two rather than from the age of five.

Adolescent↗