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Biomedical subjects

P Meadows

Publications and source records attributed to P Meadows.

11 recordsLinked to original sources
PubMed2000

The relation between tissue kallikrein excretion rate, aldosterone and glomerular filtration rate in human pregnancy.

The changes in renal kallikrein synthesis through normal pregnancy and its relation to aldosterone excretion and the glomerular filtration rate was investigated. Overnight urinary kallikrein and aldosterone excretion rates and glomerular filtration rate were measured at 18 weeks, 34 weeks, term and postpartum in normal human pregnancy. Kallikrein excretion was raised at 18 weeks compared with the nonpregnant state (P < 0 x 001) but was significantly reduced at term. The reduction in renal kallikrein was not due to falling aldosterone concentration, which increased in the third trimester, compared with 18 weeks (P = 0 x 002) and remained elevated at term compared with the nonpregnant state (P < 0 x 001). Glomerular filtration rate remained elevated at term despite the reduced kallikrein excretion rate. These data are consistent with the hypothesis that increased aldosterone production is one factor responsible for increased kallikrein synthesis which contributes to elevated glomerular filtration rate in early pregnancy. Other factors clearly inhibit renal kallikrein production at term. In the face of plasma volume expansion associated with increased mineralo-corticoid production, the effects of reduced kallikrein synthesis at term on glomerular perfusion and reabsorption of sodium by the distal tubule may predispose to blood pressure elevation in late pregnancy.

Aldosterone↗
PubMed1995

Variation of diabetes mellitus prevalence in general practice and its relation to deprivation.

This is an observational study to compare age standardized diabetes prevalences and relate these to socio-economic measures of deprivation. It includes data from eight general (family) practices in the Bristol, UK, area with no ethnic minorities affecting diabetes prevalence. A total population of 71 599 was covered, including 181 Type 1 and 901 Type 2 diabetic patients, 91 of whom were controlled with insulin, 499 with oral hypoglycaemics, and 311 with diet alone. Actual Type 1 and Type 2 diabetes prevalences were standardized to what they would be if each practice had the UK national age profile. Total standardized diabetes prevalence varied from 1.31% to 2.51% (p < 0.001) and Type 2 diabetes prevalence from 0.97% to 2.29% (p < 0.001). There was no significant variation in the prevalence of Type 1 diabetes. The Spearman rank correlation coefficient indicated a significant association between standardized diabetes prevalence and two measures, the Jarman and Townsend indices, of deprivation in the electoral ward where each practice was situated. Total standardized diabetes prevalence was significantly correlated with each of the Jarman and Townsend indices (r = 0.76, p < 0.05). Standardized Type 2 diabetes prevalence was similarly significantly correlated to each deprivation index (rs = 0.74, p < 0.05). Type 2 diabetes prevalence is affected by socio-economic factors with implications for health targets and capitation based budgets.

Adult↗
PubMed1989

Open-loop control of the freely-swinging paralyzed leg.

An experimental model has been used to study issues that are relevant to the use of electrical stimulation to help paralyzed individuals walk. Modulated stimulation sequences for the quadriceps muscles were manually selected using an iterative trial-and-error procedure to cause the knee angle to follow a specific movement pattern (desired trajectory). Four paraplegic subjects were tested before and after an eight-week program in which the quadriceps were exercised daily with electrical stimulation. It was found that 12.6 +/- 2.9 iterations were required to approximate the desired trajectory. The average error of the final match between the actual and desired trajectories was 2.1 degrees +/- 0.7. Repeated responses were extremely consistent; the average difference between successive trials was less than 1 degree in 81 percent of the trials. When the stimulation sequence was repeated every 3 s for 50 cycles, however, there was a progressive degradation in the response, even in exercised legs, that demonstrated the limitations of open-loop control. Stimulus modulation envelopes for all four subjects were similar in shape (although varied in amplitude) indicating that the iterative process can be shortened by starting with an "average" modulation envelope. Stimulation sequences achieved accurate matches of the desired trajectory on subsequent days when adjusted by a simple gain factor. The relevance of these results to multichannel control of walking is discussed.

Adult↗
PubMed1988

Tail-pinch elicited eating in rats (Rattus norvegicus) and hamsters (Mesocricetus auratus).

Noninjurious tail-pinch (TP) elicited a normal hyperphagic reaction to a milk solution in sated rats but did not increase the amount of milk solution consumed by sated hamsters. In both rats and hamsters, TP did increase the rate of eating, but did not change the amount of time spent contacting the drinking spout in rats and actually decreased the amount of time spent contacting the spout in hamsters. These results suggest that (1) the failure of hamsters to increase meal size in response to food deprivation is also generalizable to TP-induced eating, and (2) TP-induced hyperphagia may be caused by the generalized energizing effect that TP has on ongoing behavior rather than by TP stimulation enhancing the releasing properties of environmental stimuli such as the drinking spout.

Animals↗
PubMed1987

Study of the women overdue for a smear test in a general practice cervical screening programme.

Of the 1527 women aged 30-59 years in one general practice who were eligible for a cervical smear examination 196 (12.8%) were overdue for the test. These women were contacted randomly by post or in person to ascertain their reasons for not responding to the practice screening programme. Of 118 women contacted personally 47% had no major objection to the smear test but had a low view of its priority. A further 24% gave incorrect reasons for thinking a smear test was unnecessary while 29% had strong reasons for not wanting to attend and probably never would. Social and medical factors from the medical records were also examined and compared with those of a group of age and sex matched controls. It was found that women overdue for a smear test lived in more ;socially stressed' areas and used their general practitioner much less than the controls. The theoretical upper limit for smear uptake in the practice was calculated to be around 96%. To help achieve this we need to ensure: (1) that all women understand that the test is to detect a stage before cancer; (2) that some women receive more counselling; and (3) that promotional material is directed at the families of women at risk.

Adult↗