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Biomedical subjects

C P Lucas

Publications and source records attributed to C P Lucas.

10 recordsLinked to original sources
PubMed1992

The order effect: reflections on the validity of multiple test presentations.

The effect of order has been previously addressed in test-retest studies but its effect on the presentation of more than one test, in the same time, is often underestimated. This study has shown that when two rating scales were given sequentially, each scored lower if received second in the pair, and that this particular form of order effect (occasion effect) was enough to affect markedly agreement on caseness when utilizing standard cut-off scores. It is therefore important that research workers not only adopt design strategies such as counterbalanced presentation, but also analyse their data for the effects of test order and position within such designs.

Bias↗
PubMed1992

Long-term follow-up of patients attending a combination very-low calorie diet and behaviour therapy weight loss programme.

We examined the effects of treatment with a very-low calorie diet (VLCD) combined with behaviour modification on weight loss and long-term maintenance of weight loss in 118 of 199 patients who completed eight weeks of VLCD. Those who began therapy in 1984 were surveyed by telephone an average of 3.3 years after ending the VLCD. Questionnaire data included reported weight, exercise, eating, work and sleep habits, emotional factors, and current use of behavioural techniques taught in the programme. Results showed that mean maximum weight loss during the time they attended the programme (average 51.6 weeks) was 31.3 kg, corresponding to a decrease in body mass index of 10.7 kg/m2. At follow-up a regain of 60.9% was reported yielding a net overall weight loss of 13.6 kg and decrease in body mass index of 4.4 kg/m2. Seventy-five per cent of subjects showed only a 37.5% regain of the weight they had lost. Those whose weight loss was better maintained at the time of follow-up reported exercising more, eating fewer high fat foods, and using more of the behavioural techniques taught in the programme. This study provides support for the conclusion that some patients treated with VLCD and behaviour modification can maintain significant weight losses over a relatively long period of time and that specific behaviours relate to this success.

Adult↗
PubMed1991

Fluoxetine's effect on weight loss in obese subjects.

Forty-five obese subjects with a mean weight of 102.9 kg and a body mass index (in kg/m2) of 37.6 were randomly assigned to a fluoxetine-diet group (n = 23) or a placebo-diet group (n = 22) for 52 wk. At week 29, 14 subjects on fluoxetine who completed the study attained their maximum weight loss of 12.4 kg, an amount significantly greater than the maximum weight loss of 4.5 kg for the 16 on placebo who completed the study. The fluoxetine group's significantly greater mean weight loss continued through week 45. However, those on fluoxetine regained a mean of 4.2 kg from their lowest weight (P less than 0.001) whereas the placebo group did not. By the end of the study, each group weighed significantly less than they did at baseline (fluoxetine: -8.2 kg; placebo: -4.5 kg; P less than 0.05) although the difference between groups was no longer significant (P greater than 0.05). Several factors were considered as possible causes for the regain with fluoxetine.

Adolescent↗
PubMed1991

Seasonal affective disorder in adolescence.

Two adolescent girls with seasonal affective disorder (SAD) are described. It is suggested that the classic symptom profile seen in adults is not characteristic in younger subjects. Although hypersomnia is prominent, increased appetite and carbohydrate craving are rarely reported. Local meteorological data link the course of the disorder in one case to the hours of sunshine and ambient temperature during the winter months.

Adolescent↗
PubMed1991

Relationships between the amount of weight loss and post-heparin lipoprotein lipase activity in patients with type II diabetes.

The objective of this study was to investigate the changes in plasma post-heparin lipoprotein lipase activity, as it relates to the total amount of weight loss and the changes in plasma lipoproteins, during acute weight reduction and after weight maintenance in type II diabetic patients. Twenty-eight severely obese (mean weight = 106 +/- 21.7 kg, BMI = 36.4 +/- 6.0 kg/m2), diabetic patients lost, on the average, 13.3 kg on a 500 kcal (2100 kJ) diet in eight weeks. Weight loss was maintained throughout the study, which lasted 24 weeks. At the baseline, post-heparin lipoprotein lipase activity did not correlate with degree of obesity, but correlated inversely with fasting plasma glucose (r = -0.64, P less than 0.0001) and triglyceride (r = -0.63, P less than 0.0001). Both during acute caloric restriction and after weight maintenance suppression in post-heparin lipoprotein lipase activity correlated directly with the amount of weight reduction (r = 0.37, P less than 0.05 during weight loss and r = 0.42, P less than 0.03 during weight maintenance). At the end of the study patients were divided into tertiles according to the amount of weight loss achieved and baseline characteristics of the highest and lowest weight loss groups were compared. Before weight loss, despite having similar weights, the highest weight loss group had higher lipoprotein lipase activity (211 +/- 32 mU/ml vs 166 +/- 35 mU/ml, P less than 0.05) and lower plasma triglyceride (1.64 +/- 0.62 mmol/l vs 2.81 +/- 1.28 mmol/l, P less than 0.05) as compared to the lowest weight loss group.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoprotein A-I↗
PubMed1977

The effect of conjugated estrogens on the renin-angiotensin system.

In a survey of 3 California communities by the Stanford Heart Disease Prevention Program, we obtained data on blood pressure, medications, age, height and weight, blood for measurement of plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin reactivity (RR), and plasma renin substate concentration (PRS), and urine for measurement of urinary sodium and creatinine. No effect of conjugated estrogens (Premarin) on blood pressure could be discerned when the blood pressure, corrected for age and relative weight, of 575 women on no medication was compared to that of 82 women taking only Premarin. Premarin increased PRA, PRS, and RR, but had no effect on PRC. We also found in both Premarin-treated woman and controls 1) that RR was positively correlated with PRS, and 2) that PRA is dependent on PRC and PRS. These data indicate that the reninrenin substrate reaction of plasma, even at normal substrate concentration, is strongly deprendent on PRS.

Adult↗
PubMed1977

Renin-renin substrate kinetic constants in the plasma of normal and estrogen-treated humans.

The renin-renin substrate Michaelis constant (Km) and maximal velocity (Vmax) were determined in the plasmas of normal subjects. The mean Km was 0.7 microgram/ml. Under these conditions, the in vitro reaction of renin with physiologic concentrations of renin substrate will proceed at only 70% of its maximal velocity. Following estrogen administration, Km doubled to a value of 1.3 microgram/ml. Vmas increased by 81%. Analysis of the changes induced in the in vitro reaction velocity demonstrated that estrogen-induced acceleration of the renin reaction is dependent upon both an increase in renin substrate concentration as well as an increase in Vmas. The latter appears to be quantitatively more important. These findings suggest the emergence of modifying factors in the renin-renin substrate interaction following estrogen administration.

Angiotensinogen↗
PubMed1975

A plasma inhibitor of the renin-antirenin reaction and the in vitro generation of angiotensin I.

In the course of studies designed to develop a radioimmunoassay system for the detection of renin, we have identified in human plasma a potent inhibitor that interferes with the renin-antirenin reaction. Utilizing gel filtration, this renin-antirenin inhibitory activity was found to have the same molecular size as renin substrate. However, it could be separated from renin substrate by ion-exchange chromatography. When fractions containing this activity were tested in an in vitro system containing renin and renin substrate, they were found to inhibit the generation of angiotensin I.

Angiotensin II↗
PubMedDate not supplied

Aldosteronism.

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Adrenocorticotropic Hormone↗