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Biomedical subjects

J Terpstra

Publications and source records attributed to J Terpstra.

At least 19 recordsLinked to original sources
PubMed1998

Selective alteration of personality and social behavior by serotonergic intervention.

OBJECTIVE: The authors sought to test the causal hypothesis that serotonergic function modulates aspects of the normal spectrum of individual differences in affective experience and social behavior in humans. METHOD: A selective serotonin reuptake inhibitor (SSRI), paroxetine, 20 mg/day (N = 26), or placebo (N = 25) was administered to normal volunteers in a double-blind manner for 4 weeks, and personality variables and social behavior were assessed at baseline and at weeks 1 and 4 of treatment. RESULTS: Relative to placebo, SSRI administration reduced focal indices of hostility through a more general decrease in negative affect, yet did not alter indices of positive affect. In addition, SSRI administration increased a behavioral index of social affiliation. Changes in both negative affect and affiliative behavior were significantly related to volunteers' plasma SSRI levels at the end of the experiment. CONCLUSIONS: Central serotonergic function may modulate a dimension of normal personality characterized by reduced negative affective experience and increased affiliative behavior. SSRI administration has significant and detectable effects on these measures even in the absence of baseline clinical depression or other psychopathology.

Adult↗
PubMed1995

Injury surveillance at the USTA Boys' Tennis Championships: a 6-yr study.

Injuries that required physical or medical assistance were recorded for participants at the United States Tennis Association National Boys' Tennis Championships from 1986-1988, 1990-1992 (N = 1440, 240 athletes per year). Over the 6-yr period, a total of 304 athletes (or 21.1%) sustained new or recurrent injuries that required evaluation by the medical team. New injuries alone numbered 145 (incidence rate of 9.9 per 100 athletes). The analysis of injuries showed a higher rate of lower than upper extremity injuries. When evaluated by anatomic regions, back injuries were most common followed by thigh, shoulder, and ankle injuries, respectively. When evaluated by injury type, strains and sprains were most common (71% of all injuries) with fractures and dislocations being rare (1.3% of all injuries). The lower extremity provided the majority of sprain type injuries with 87.5% of ligament sprains coming from the knee and ankle. Injuries with tennis eponyms (i.e., tennis toe, tennis leg, tennis elbow, and tennis shoulder) were rare (0%-5% of all injuries). It would appear that these young elite athletes are at significant risk of injury.

Adolescent↗
PubMed1985

Diurnal changes in serum triglycerides as related to changes in lipolytic enzymes, lipoproteins and hormones in patients with primary endogenous hypertriglyceridaemia on a carbohydrate-rich diet.

Parameters of diurnal triglyceride (TG) metabolism were investigated in 5 subjects with primary endogenous hypertriglyceridaemia and compared with those of normal subjects studied previously. The patients were in a steady state on a carbohydrate-rich diet (meals at 9.00, 13.00 and 17.00 h). Serum TG showed a wavelike pattern with a maximum at around 17.00 h. Post-heparin lipoprotein lipase (LPL) activity in the fasting state was not different from that in normals, but failed to show the normal increase in the fed state (16.30 h). This was due to the inability of patients to increase their adipose tissue (AT)-LPL activity in the course of the day. AT-LPL activity was throughout the day lower than in normal subjects. Skeletal muscle LPL activity was low and showed no diurnal change, equalling our findings in normal subjects. Low density lipoprotein cholesterol and high density lipoprotein (HDL) cholesterol concentrations showed no diurnal change. However, HDL phospholipids increased significantly in the course of the day.

Adipose Tissue↗
PubMed1985

Diurnal course of the suitability of serum samples obtained from normal subjects and from patients with primary endogenous hypertriglyceridaemia to serve as substrate for milk lipoprotein lipase.

Serum samples, obtained at various times of the day from four normal subjects and five patients with primary endogenous hypertriglyceridaemia on a carbohydrate-rich diet (meals at 09.00, 13.00 and 17.00 h), were incubated with cows' milk lipoprotein lipase (LPL) to investigate the susceptibility of the triglyceride(TG)-rich lipoprotein fraction to hydrolysis. Mean KM and vmax of this reaction increased in patients between 09.00 and 13.00 h (p = 0.016 and 0.015, respectively) and decreased again thereafter, whereas no diurnal change was observed in normal subjects (p = 0.31 and 0.27, respectively). At 13.00 and 23.00 h patients showed a higher mean KM (p less than 0.02) at 23.00 h a higher mean vmax (p less than 0.03) than normal subjects. When the data were expressed as reaction rates (FFA formation rates) at TG-concentrations in the in vivo range, neither group showed a diurnal difference. Patients showed a significantly lower reaction rate than normal subjects only at 13.00 h at TG concentrations below 3 mmol X 1-1. This suggests that a defect in the suitability of TG-rich particles to serve as a substrate for LPL is not likely to play a role in the development of hypertriglyceridaemia.

Adult↗
PubMed1983

Diurnal changes in serum triglycerides as related to changes in lipolytic enzymes, (apo) lipoproteins and hormones in normal subjects on a carbohydrate-rich diet.

Normal subjects in steady state on a carbohydrate-rich diet (three equivalent meals a day at 9.00, 13.00 and 17.00 h), show a wave-like serum triglyceride (TG) pattern with a peak at 14.00 h. Post-heparin lipoprotein lipase (LPL) activity increased from a mean value of 49 mU/ml +/- 13 (SD) in the fasting state to 127 mU/ml +/- 18 in the fed state (P less than 0.005). This was due to an increase in adipose tissue LPL activity which, at 16.30 and 21.30 h, was significantly higher than basal levels (128.3 +/- 81.5 and 87.7 +/- 23.2 v. 43.3 +/- 9.3 mU/g, P less than 0.05 and P less than 0.01, respectively). Skeletal muscle LPL activity was low (5.8 mU/g +/- 2.3, mean +/- SD) and showed no diurnal change. The observed changes in TG-hydrolysing capacity in the course of the day might explain the TG-pattern. High density lipoprotein (HDL) subfractions HDL2 and HDL3 were separated by density gradient ultracentrifugation and had mean hydrated densities of 1.088 and 1.135 g/ml, respectively. While HDL2 showed no diurnal change, HDL3-cholesterol and-phospholipid significantly increased during the day (P less than 0.005 and P less than 0.001 respectively), reaching their highest levels in the evening. Since te rise in HDL3-lipids follows the fall in serum TG, this provides further indication that the metabolism of these fractions in mutually related.

Adipose Tissue↗
PubMed1981

Diurnal levels of lipids, glucose and insulin in type IV hyperlipidemic patients on high carbohydrate and high fat diet: comparison with normals.

Diurnal levels of serum triglyceride (TG), cholesterol, free fatty acids (FFA), glucose and insulin were measured in three type IV hyperlipidemic patients on a fixed solid 65% carbohydrate and a 65% fat diet when in steady state conditions in a metabolic unit. The carbohydrate-rich food was divided into either three or eight equivalent portions, differently spaced over the day and night. The fat-rich food was given in three equivalent portions only. The diurnal TG profiles on these diets showed the same characteristics as those found in normals, but increments and mean levels were considerably higher. On the carbohydrate-rich diet, mean TG levels decreased during the study. This was not seen either on the fat-rich diet or in normals. In contrast to our findings in normals, chylomicrons formed the major contribution to the serum TG pattern. FFA levels were markedly higher on the high-fat than on the carbohydrate-rich diet, but not different from those in normals. Postprandial glucose responses did not differ significantly between the diets. Insulin responses were markedly higher on the carbohydrate-rich than on the fat-rich food. Glucose levels did not differ from those in normals. Insulin levels were significantly higher in the patients. Cholesterol showed minimal fluctuations, parallel to the TG pattern, which could be attributed to chylomicron cholesterol.

Adult↗
PubMed1979

Photocoagulation treatment in diabetic retinopathy: a two-year pre- and five-year post-treatment study.

A randomized controlled study covering a two-year pre-treatment and a five-year post-treatment period was performed in 42 patients with diabetic retinopathy given photocoagulation treatment in one eye. Patients with progressive diabetic retinopathy of equal intensity in both eyes were selected from a single diabetes department. The course of diabetic retinopathy was assessed by ophthalmoscopy and composite fundus photographs as well as fluorescence angiography. In the first two-year post-treatment period non-proliferative retinopathy improved in the coagulated eyes and also, albeit to a lower degree, in the control eyes. In the next three years the treated eyes showed further improvement or stabilization, whereas the control eyes showed either stabilization or deterioration of the retinopathy. The most favourable results were obtained in proliferative diabetic retinopathy, which regressed in the majority of the eyes, the other eyes remaining stable or progressing only very slightly, in contrast with the control eyes, in the great majority of which proliferative diabetic retinopathy developed or progressed.

Adult↗
PubMed1979

Influence of meal frequency on diurnal lipid, glucose and insulin levels in normal subjects on a high fat diet; comparison with data obtained on a high carbohydrate diet.

Diurnal levels of serum triglyceride (TG) were measured in six normal persons consuming a fixed solid 65% fat diet under steady state conditions in a metabolic unit. The food was divided into either three or eight similar portions, differently spaced over the day and night. The diurnal TG-profiles on this diet were practically identical to those found under comparable conditions on a 65% carbohydrate diet [1]. Mean diurnal TG values did not significantly differ with varying meal frequency. Free fatty acid levels, however, were significantly higher on a high fat diet. Post-prandial glucose and insulin reponses did not significantly differ whether a high fat diet or a high carbohydrate diet was consumed. We conclude that the composition of the diet is of little importance in determining diurnal TG patterns when the diet consists of normal food stuffs, but that these patterns are dependent on meal frequency and distribution.

Blood Glucose↗
PubMed1978

The influence of meal frequency on diurnal lipid, glucose and cortisol levels in normal subjects.

Diurnal levels of serum triglyceride, cholesterol, free fatty acids, glucose, and cortisol were measured in four normal persons on a fixed solid 65% carbohydrate diet under steady state conditions in a metabolic unit. Triglyceride levels in all subjects showed similar patterns, which unexpectedly did not bear a simple relation to meal frequency or distribution. With three equivalent meals per day at 09.00, 12.00 and 17.00 hours, 'fasting' triglyceride levels increased by about 0.3 g/l from a minimum value between 03.00 and 05.00 hours in the morning till before breakfast. After breakfast there was a continued rise till about 15.00 hours and then a overall fall in spite of the meal at 17.00 hours. Isocaloric change to eight equivalent meals, consumed between 09.00 and 23.00 hours, resulted in a similar although slightly more even triglyceride pattern. On eight equivalent meals, spaced evenly over the entire 24 h period, a different pattern was found with lower triglyceride values at daytime than at night. Increase in meal frequency did not result in a lowering of mean diurnal triglyceride levels. The cholesterol pattern followed the triglyceride pattern most clearly in subjects with high triglyceride levels. Glucose showed the expected postprandial increments. Cortisol rhythm did not change on varying meal frequency.

Adult↗
PubMed1976

Some properties of a microsomal oleate desaturase from leaves.

1. When [1-14C]oleoyl-CoA was incubated with a pea-leaf homogenate oleate was both incorporated into microsomal 3-sn-phosphatidylcholine and released as the unesterified fatty acid. The proportion of oleate incorporated into this phospholipid was dependent on the relative amounts of thiol ester and microsomal preparation present in reactions. 2. At the concentrations of microsomal preparation and [14C]oleoyl-CoA used to study oleate desaturation the metabolism of the thiol ester was essentially complete after 5 min incubation, but the loss of label from 3-sn-phosphatidylcholine oleate and the concomitant increase in radioactivity in the linoleate of this phospholipid proceeded at approximately linear rates over a 60 min period. The kinetics of labelling of unesterified linoleate was consistent with the view that this labelled fatty acid was derived from 3-sn-phosphatidylcholine. 3. Oleate desaturation required oxygen and with unwashed microsomal fractions was stimulated either by NADPH or by the 105 000g supernatant. Washed microsomal preparations did not catalyse desaturation, but actively was restored by the addition of NADPH, 105 000G supernatant or Sephadex-treated supernatant. NADPH could be replaced by NADH or NADP+, but not by NAD+. 4. Microsomal fractions from mature and immature maize lamina and expanding spinach leaves also rapidly incorporated oleate from ([14C]oleoyl-CoA into 3-sn-phosphatidylcholine, but desaturation of 3-sn-phosphatidylcholine oleate was detected only with microsomal preparations from immature maize lamina. 5. It is proposed that leaf microsomal preparations posses an oleate desaturase for which 3-sn-phosphatidylcholine oleate is either the substrate or an immediate precursor of the substrate.

Acetates↗