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Biomedical subjects

I Davies

Publications and source records attributed to I Davies.

At least 55 records · Page 3Linked to original sources
PubMed1988

A new urethral catheter.

A new balloon catheter for women with a flexible urethral portion that conforms to the shape of the closed urethra was tested. In sheep control catheters caused epithelial destruction, which was absent with the conformable catheter. A 12 week crossover trial compared control catheters in 52 long stay geriatric patients. Eighty two out of 91 conformable catheters were rated as comfortable compared with 68 of 87 control (p = 0.006). The average length of time in situ was 15.9 days for the conformable catheter compared with 12.9 days for the control (p = 0.001). The average number of bypasses a week with the conformable catheter was 1.1 compared with 1.3 for the control; this difference was not significant. Examination of 249 used catheters showed significantly fewer with intraluminal obstruction with struvite among the conformable than control catheters (1 (0.8%) versus 15 (11.5%); p less than 0.001). This new catheter for women is a substantial improvement over the Foley catheter and (except in urethral stricture) is suitable for all forms of drainage.

Aged↗
PubMed1988

Age changes in the human female urethra: a morphometric study.

Aging in the human female urethra can contribute towards urinary problems. To our knowledge the effect of age on urethral tissues has not been quantified previously. Histological sections were prepared from 8 regions along the length of the urethra from 26 women between 19 and 88 years old. Using quantitative morphological techniques the relative volume fractions of various tissue components were determined. As age increased there was a decrease in the relative volume of striated muscle and blood vessels, and an increase in the relative volume of connective tissue. There was no change in the smooth muscle components. These age changes in the human female urethra may lead to impairment of urethral function.

Adult↗
PubMed1988

Age-related changes in the stomach of the laboratory mouse: a quantitative morphological study.

This report is of a quantitative morphological investigation of the gastric wall in the aged laboratory mouse. Male mice of 6, 9, 18, 28 and 34 months of age were killed and the mid-greater curvature of the stomach examined qualitatively and quantitatively for age-related changes. There was no evidence of superficial or atrophic gastritis in any of the mice investigated. There were significant decreases in the relative volumes of parietal and chief cell components with age, and a significant increase in other components in the lamina propria. The relative volume of the mucous cell compartment did not change with age. In all cases where a significant change was observed it took place in the 34-month-old age group when compared with 6-, 9- or 18-month-old animals. There was a progressive change in the components after 18 months of age but this only achieved significance at 34 months. It was concluded that alterations in the gastric wall take place later in the life-span and appear to be a physiological, rather than a pathological change.

Aging↗
PubMed1987

The effect of vitamin E deficiency on the induction of age pigment in various tissues of the mouse.

The effect of a dietary deficiency of vitamin E on the concentrations of lipofuscin in the hippocampus and the supraoptic nucleus (SON) of the hypothalamus, and in adrenal cortical cells was assessed in male mice. The animals were fed either a control diet or the vitamin E deficient diet after 2 months of age for a period of 6 months. There was no significant difference in the growth curves of the 2 groups of animals over the period studied. Fluorescence microscopy and transmission electron microscopy were used to assess the effect of the diet on lipofuscin in the different tissues. Quantitative morphological techniques were used to determine the relative volumes of lipofuscin in the neurons from the SON and in the adrenal cortical cells. There was no significant difference in the concentration of lipofuscin in the SON neurons after vitamin E deficiency but there was a significant increase in the adrenal cortical cells. There was a clear difference in the effect of the deficiency on mitotic and fixed post-mitotic cells over the period investigated but further studies would be necessary to determine whether or not there was a critical period in the life span where vitamin E deficiency may induce changes in all cell types.

Adrenal Cortex↗
PubMed1987

The epithelium in the female urethra: a quantitative study.

Histological sections were prepared from 8 regions along the length of the urethra in 16 women 19 to 82 years old. The epithelium was examined under the light microscope at 4 points in each region and the type of epithelium was classified. Our results indicate that the human female urethra is lined by stratified squamous, pseudostratified columnar and, occasionally, transitional epithelium. There is a gradual change from squamous to columnar epithelium with advancing age. More squamous epithelium is present at the distal end of the urethra.

Adult↗
PubMed1987

Long-term study of the immuno-pathological consequences of sympathetic orchiopathia in the rat.

Unilateral testicular ischaemia was induced in Wistar rats by ligation and division of the testicular and deferential vessels. Damage (as assessed by a Johnsen count) to the contralateral testis caused significant spermatogenic suppression only at the equator of the testis at 28 days after operation. Cytotoxic antisperm antibody production increased progressively from 7 to 14 days and became maximal at 28 days after infarction, but after 3 and 6 months antibody production was decreasing. The presence of agglutinating antisperm antibody was noted at 28 days, 3 months and 6 months after infarction. Serum immunoglobulin estimations revealed an increase in IgG and IgM levels at 7 days and IgM levels at 14 days, supporting the contention that an immunological reaction had occurred. It is suggested that unilateral testicular ischaemia in the rat, an animal model intended to mimic torsion of the testis in the human, causes a transient immunological phenomenon (sympathetic orchiopathia) which recovers over the course of time. Caution should be exercised before regarding this relatively common surgical emergency as an aetiology of oligospermia or asthenospermia.

Agglutination Tests↗
PubMed1987

Renal vasopressin receptors in ageing C57BL/Icrfat mice.

The mechanism of water conservation is impaired in ageing mammals. An age-related defect in the release of vasopressin has been implicated but, more recently, attention has moved to the renal component of the water conservation mechanism. Previous studies using renal cells prepared from mice of different ages have shown that the threshold dose of vasopressin required to elicit a significant rise in cyclic AMP (cAMP) was greater in older animals. The dose-response curve was moved to the right in 35-month-old mice, i.e. the concentration of vasopressin required to give maximum cAMP output was increased. To investigate this further we examined the binding of vasopressin to renal medullary cells maintained in short-term culture, to determine whether the decreased response of cAMP levels to vasopressin is due to changes in hormone-receptor interaction. In 6-month-old male mice the dissociation constant (Kd) was 2.38 nmol/l and the maximum binding of the hormone (Bmax) was 47.6 fmol/10(6) cells, and at 30 months of age Kd was 2.37 nmol/l and Bmax was 47.0 fmol/10(6) cells. In female mice the changes were more complicated because the data for the 6-month-old mice could be split into two groups. It is concluded that there are no age-related differences in the numbers of receptors or their affinity for vasopressin, and that the decreased cAMP response is probably associated with post-receptor mechanisms in this species.

Aging↗
PubMed1987

Ageing in the hypothalamo-neurohypophysial-renal system.

Ageing is characterised by a failure in the maintenance of the internal environment (homeostasis) which is regulated by the hypothalamic neuroendocrine system. Of the many systems that undergo age-related degeneration is the control of water metabolism which leads to a variety of complications in the elderly. The magnocellular neurons of the hypothalamus produce the peptide anti-diuretic hormone (vasopressin) which acts on the kidney regulating water loss in the urine. This physiological axis lends itself to both fundamental studies of the cellular and molecular biology of ageing, and to studies of age-related alterations in the functional ability of elderly people. This review summarises some of the recent research into age-related changes in this system. The morphological and functional changes in the hypothalamus, neurohypophysis and kidney are described for the various species examined and the results discussed in terms of ageing in humans.

Aged↗
PubMed1986

Cardiovascular haemodynamics and the response of vasopressin, aldosterone, plasma renin activity and plasma catecholamines to head-up tilt in young and old healthy subjects.

Increasing age impairs the regulation of blood pressure during posture change. The neuro-humoral and cardiovascular responses to head-up tilt were analysed in carefully-screened young and healthy elderly individuals. Mean blood pressure was significantly higher in the elderly but there were no differences in total peripheral resistance, heart rate, stroke volume and cardiac index. Age-related interactions were observed in the control of mean blood pressure, heart rate and stroke volume. Total peripheral resistance increased and cardiac index decreased but there was no difference in their control in the young and old. Noradrenaline, vasopressin, plasma renin activity and aldosterone all increased in response to the tilt. These observations indicate differences in the neuroendocrine responses and cardiovascular haemodynamics of young and old healthy individuals to head-up tilt and are particularly important because of all observations were made simultaneously in the same subject. It is suggested that a similar approach should be adopted in the investigation of patients with postural hypotension.

Adult↗
PubMed1985

The effect of age on the control of water conservation in the laboratory mouse--metabolic studies.

Age-related changes in the intake of food and water, and the output of faeces and urine were investigated in C57BL/Icrfat mice of 6 and 24 months of age. Animals were singly housed in a metabolic cage for a period of 30 days. 14 days were allowed for acclimatization before the animals were dehydrated for 24 hours. 10 days of rehydration were allowed prior to a hyperosmotic challenge with 3% sodium chloride in the drinking water. The animals were then observed for 5 more days of rehydration. Urine was collected and analysed with regard to sodium, potassium, urea and vasopressin output/24 hours (/100g body weight), and the osmotic pressure of the urine was determined. Data were analysed by a 2 factor analysis of variance with repeated measures on one factor. Significant changes were detected in the control of body weight, potassium, sodium and urea outputs. No age-differences were detected in the intake of food or water, the output of faeces or urine, the urine osmotic pressure or the excretion of vasopressin. However, significant changes in these variables were detected in both age groups on the days of physiological challenge. The conclusion drawn is that in the mouse strain studied, and for the period of the lifespan investigated, there is no age related defect in the secretion of vasopressin. However, there are trends in the data suggesting a decreased responsiveness of the kidney with age.

Age Factors↗
PubMed1985

Contracts to bear children.

In the surrogate mother procreation can be divorced both from sex as well as any anticipation of child rearing. Often the risks of surrogate motherhood are presented in terms of alternative family structures and economic exploitation of women. Such possibilities must invite critical reflection in order for there to be legal reform. Of paramount importance is the child's best interest and until the full psychological is the child's best interest and until the full psychological ramifications for the child, adoptive parents and natural mother are determined then the law's role must be ambivalent. In this impasse the minority view of the Warnock Report has much to commend itself.

Advisory Committees↗
PubMed1984

The effect of osmotic challenge and subsequent rehydration on the aging hypothalamo-neurohypophyseal system. A quantitative morphological study of the supraoptic nucleus.

The neurons of the supraoptic nucleus (SON) of male C57BL/Icrfat mice at 6 or 28 months of age were examined from normally hydrated, osmotically loaded and osmotically loaded/rehydrated animals. Using quantitative morphological techniques it was shown that the majority of the ultrastructural variables investigated were controlled in the same way in the SON neurons of young and old mice. The major exception was the mitochondrial compartment which although maintaining a constant proportion of the volume of the SON cell did show a significant reduction in the number of mitochondria in the old group, particularly during the osmotic challenge period of the experiment. The "lipid" body compartment of the SON neuron also behaved differently in the cells from the older age group. This study when viewed in conjunction with previous investigations suggests that these SON neuroendocrine neurons from old animals are able to produce hormone until late in the life-span. However, other aspects of cellular activity appeared to be altered when judged by morphological criteria. It is concluded that the SON neurons from these old mice are able to synthesize hormone-containing organelles to the same concentration as the cells from a younger animal. However, the efficiency of the process, or at least the efficiency of concomitant cellular processes, must be questioned in view of the alterations in the rough endoplasmic reticulum, mitochondrial and lysosomal systems.

Aging↗
PubMed1984

Which computer?

Explore the source record for details and available documents.

Computers↗
PubMed1984

Plasma arginine vasopressin in dehydrated elderly patients.

Plasma arginine vasopressin was assessed by radioimmunoassay in dehydrated elderly patients and healthy young and elderly control subjects. The elderly control subjects' AVP levels were higher than the young control subjects (Kruskal-Wallis rank sums z = 3.29; P less than 0.001). Despite similar plasma osmolalities, after correction for the osmotic contribution of urea, the patients' AVP levels were higher than the elderly controls (z = 4.16; P less than 0.001) and were in the range reported to evoke a maximal antidiuretic response. It is concluded that the dehydration which often accompanies acute illness in the elderly is not primarily a consequence of inadequate AVP release.

Adult↗
PubMed1984

Effect of ageing on cyclic AMP output by renal medullary cells in response to arginine vasopressin in vitro in C57BL/Icrfat mice.

The effect of age on the cyclic AMP (cAMP) response to increases in the concentration of arginine vasopressin in the presence of isobutyl methylxanthine (100 mumol/l) was studied in an in-vitro renal cell suspension prepared from C57BL/Icrfat mice at 6, 12, 18, 24, 29 and 35 months of age. Comparison of the response of the preparation to vasopressin, calcitonin and parathyroid hormone suggested that it was enriched with renal medullary cells. Basal cAMP output was similar throughout but the threshold dose of vasopressin increased from 1 X 10(-11) mol/l (6, 12 and 18 months of age) to 1 X 10(-10) mol/l (24, 29 and 35 months of age). The dose-response curve in 35-month-old mice was shifted to the right with the concentration of vasopressin required to give half maximal cAMP increased from 9.4 +/- 0.37 X 10(-11) mol/l (6 months) to 3.5 +/- 1.6 X 10(-10) mol/l (35 months). Maximum cAMP output at 1 X 10(-9) mol/l was also reduced in the same animals (stimulated:basal ratio, 51.22 +/- 19.12 at 6 months; 11.50 +/- 6.02 at 35 months). The results suggest that the lack of renal response to vasopressin in terms of cAMP metabolism may play a role in the well-documented age-related decline in urine-concentrating ability in experimental animals and elderly people.

Aging↗
PubMed1983

Polyuria and inappropriate secretion of arginine vasopressin in hypothalamic sarcoidosis.

Inappropriate arginine vasopressin release and polyuria with excessive thirst were found in a patient with hypothalamic sarcoidosis subsequently confirmed at autopsy. He became intensely thirsty during a 5% saline infusion at a plasma osmolality of 274 mosmol/liter. The normal thirst threshold under these conditions is 294 +/- 3 mosmol/liter (+/- SD). An increase in radioimmunoassayable arginine vasopressin was detected at an inappropriately low plasma osmolality, and free water clearance was negative despite a plasma osmolality of 265 +/- 5 mosmol/liter with ad libitum fluid intake. The syndrome of inappropriate antidiuresis has not been described previously in combination with hypothalamic sarcoidosis. Demeclocycline therapy was associated with an exacerbation of the patient's polyuria. Propranolol administration, however, was associated with a reduction of urine output and an increase in plasma osmolality to 279 mosmol/liter on one and 299 mosmol/liter on another occasion.

Adult↗
PubMed1981

The influence of age on the response of the supraoptic nucleus of the hypothalamo-neurohypophyseal system I. Ultrastructural aspects.

The influence of age on the response of the supraoptic nucleus (SON) of the hypothalamo-neurohypophyseal system to physiological stress has been studied by means of the electron microscope. An osmotic load was applied to male C57BL/Icrfat mice at 6 and 28 months of age and the resulting changes in the ultrastructure of SON cells in response to this stress analysed. In the young animals the differences in morphology observed between the SON cells from control and from those of salt-loaded mice were very similar to those seen in salt-stressed rats at a similar age. Qualitative differences were noted in several sub-cellular components of old, salt-stressed mice. The mitochondria showed evidence of ultrastructural damage in cells from the old, stressed animals. The Golgi system and the rough endoplasmic reticulum both showed heterogeneity in structure when compared with cells from young salt-stressed mice. In addition, there was a decrease in the lipofuscin content of old, salt-stressed mice. These changes are discussed with respect to the overall efficiency of cellular activity in old, physiologically stressed animals.

Aging↗