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Biomedical subjects

A D Kester

Publications and source records attributed to A D Kester.

At least 19 recordsLinked to original sources
PubMed1997

Effect of the dietary fat type on arterial thrombosis tendency: systematic studies with a rat model.

To study the influence of dietary fatty acids on arterial thrombosis tendency 65 groups of male rats were fed diets containing 50% of their digestible energy as fat from 32 different oils and fats. After 8 weeks their arterial thrombosis tendency was assessed by measuring the obstruction time (OT) of a loop-shaped polythene cannula inserted into the abdominal aorta. Using multiple regression analysis log10 OT was modelled as a function of the relative amounts of the various dietary fatty acids and their combinations. The best fit (R2 = 0.79) was obtained for the sums of all monoenoic and (n-6) and (n-3) polyenoic fatty acids, which appeared antithrombotic. The fit for the sum of all saturated fatty acids, which had a prothrombotic effect, was almost as good (R2 = 0.76). The ratio between dietary polyunsaturated and saturated fatty acids (P:S ratio) appeared a strong predictor of arterial thrombosis tendency (R2 = 0.77). Marine oils did not have a more powerful antithrombotic effect than could be expected on the basis of their P:S ratios. Using stepwise regression analysis myristic acid, 14:0, was shown to be the strongest prothrombotic fatty acid whereas linoleic acid, 18:2(n-6), was the strongest antithrombotic fatty acid. Since the number of marine oils was very limited the effects of the 'fish fatty acids' eicosapentaenoic acid, 20:5(n-3) and docosahexaenoic acid, 22:6(n-3), on arterial thrombus formation could not be tested reliably. The same appeared true for gamma-linolenic acid, 18:3(n-6), and stearidonic acid, 18:4(n-3), present in a few vegetable oils only.

Animals↗
PubMed1997

Fitting a routine health-care activity into a randomized trial: an experiment possible without informed consent?

Due to possible methodological and practical problems, many researchers refrain from using a randomized controlled trial design to evaluate procedures already embedded in routine health care. We performed a randomized controlled trial on the effects of routine individual feedback on test ordering behavior of family physicians. The trial started after 4 years of feedback and lasted for 2.5 years. With some adaptations a randomized trial proved to be possible. In evaluating health-care procedures that cannot be blinded in a traditional way, asking full and study-specific informed consent may conflict with the validity of the design. In such studies, an alternative procedure is to be considered. Our trial, with doctors as study subjects, was held on an already accepted routine procedure (feedback). This made it possible to refrain from obtaining study-specific informed consent. Consequently, a Hawthorne effect and contamination of the trial arms through information leakage could be avoided. Justification and general criteria for not obtaining full and study-specific informed consent are worked out. In health-care research on the performance of doctors or on interventions into the quality of care, obtaining a general informed consent in advance is an acceptable alternative approach.

Diagnostic Tests, Routine↗
PubMed1997

Essential fatty acid status in plasma phospholipids of mother and neonate after multiple pregnancy.

During singleton pregnancy, maternal essential fatty acid (EFA) status decreases progressively. After multiple pregnancy it can be expected that the neonatal and maternal EFA status is even lower. To study whether the maternal EFA supply to the fetus is a limiting factor to the neonatal EFA status, we compared the plasma phospholipid EFA status of newborn multiplets (30 pairs of twins and 7 sets of triplets) with that of singletons (n = 89) at birth and that of their mothers at delivery. After correction for gestational age, a slightly lower EFA status was found in maternal and umbilical plasma from multiplets compared to singletons. No relation was found between the difference in birthweight of the smallest and the largest neonate of a set of multiplets and the difference in cord plasma EFA levels. Correlations between maternal and umbilical plasma EFA levels were comparable for multiple and singleton pregnancies. Therefore, adequate dietary intake is required to guarantee an optimal neonatal EFA status, especially during multiple pregnancy.

Birth Weight↗
PubMed1996

Essential fatty acid status measured in umbilical vessel walls of infants born after a multiple pregnancy.

The essential fatty acid (EFA) status of full-term infants born after an uneventful, singleton pregnancy has been reported to be marginal. If this low EFA status is caused by a limiting maternal EFA supply, the higher total fetal EFA demand associated with a multiple pregnancy would result in an even lower EFA status of the infants born after a multiple pregnancy. Therefore, we compared the EFA status at birth of 30 pairs of twins, seven sets of triplets, and one set of quintuplets with that of 94 infants (51 preterm, 43 full-term) born after a singleton pregnancy. Phospholipid-associated EFA profiles of the umbilical vessel walls, considered a longer-term reflection of the fetal EFA status, were studied. After correction for gestational age at birth, levels of n-6 and n-3 EFAs were generally lower, while levels of EFA-deficiency indicating n-9 polyunsaturated fatty acids were significantly higher both in the draining umbilical arteries and the supplying veins of infants born after a multiple pregnancy. EFA profiles of twins and triplets were similar, but the average EFA status of the set of quintuplets was lower than that of twins and triplets. In conclusion, the observation that the EFA status of infants born after a multiple pregnancy is lower than that of infants born after a singleton pregnancy supports the view that the maternal EFA supply to the fetus is limiting. Considering the importance of EFAs and their longer chain derivatives for proper growth and development, this finding warrants further studies of the adequacy of the maternal EFA intake during pregnancy.

Adult↗
PubMed1996

Essential fatty acid status of fetal plasma phospholipids: similar to postnatal values obtained at comparable gestational ages.

Hardly any direct information is available on the essential fatty acid (EFA) status of the fetus during intrauterine development. Therefore, we studied 86 umbilical plasma samples obtained by trans-abdominal puncture during ongoing pregnancies (18.3-39.0 weeks of gestational age). These were compared with 51 samples of umbilical cord blood, collected immediately after birth (gestational ages, 28.5-39 weeks). The total amounts of fatty acids in fetal plasma phospholipids (mg/l) did not change during gestation. The relative amounts of linoleic acid (% of total fatty acids) showed a slight increase (P = 0.03) during fetal maturation. Arachidonic acid (20:4n-6) decreased (both absolute (mg/l) and relative (% wt/wt) P < or = 0.0001), while docosahexaenoic acid (22:6n-3) increased (absolute P < 0.003, relative P < 0.0001) when pregnancy progressed. The EFA profiles of fetal samples were in general comparable with postnatal results of infants born at similar gestational ages. However, the fetal linoleic acid status was lower than the linoleic acid status of the neonates. The same was true for the overall EFA status. The results of this study indicate that the low EFA status observed in preterm infants at birth, is a developmentally related phenomenon.

Fatty Acids, Essential↗
PubMed1996

The diagnostic value of the measurement of the ankle-brachial systolic pressure index in primary health care.

We investigated the value of the ankle-brachial systolic pressure index (ABPI) as a test for the diagnosis of peripheral arterial occlusive disease (PAOD) in general practice. ABPI measurements on 231 legs of 117 subjects performed in three general practice centers (GPC) were compared with the diagnostic conclusions of a Vascular Laboratory. The optimum cutoff value for the ABPI, its accuracy and diagnostic value were estimated. In a subpopulation of 51 subjects for whom repeated measurements were available, we checked whether taking the mean of three consecutive ABPIs for test outcome would enhance diagnostic performance. Receiver Operating Characteristic analysis showed that overall performance of the GPC ABPI was good (area under the curve approximately 0.9). Performing repeated ABPI measurements was superior to performing a single measurement. The optimum cutoff value for the ABPI was 0.97, associated with a diagnostic odds ratio (OR) of 17 and an accuracy of 81%. In a somewhat more selected subpopulation, the optimum cutoff value was 0.92 (OR 70, accuracy 90%). On the basis of our results, we suggest the following rule of thumb: if the ABPI < 0.8 or if the mean of three ABPIs < 0.9, it is highly probable that PAOD is present (PV+ > or = 95%); if the ABPI > 1.1 or if the mean of three ABPIs > 1.0, PAOD can be ruled out (PV- > or = 99%). In conclusion, in primary health care, the ABPI measurement can be a useful supplementary test in ambiguous diagnostic situations with regard to PAOD.

Adult↗
PubMed1996

Influence of feeding artificial-formula milks containing docosahexaenoic and arachidonic acids on the postnatal long-chain polyunsaturated fatty acid status of healthy preterm infants.

In view of the importance of long-chain polyunsaturated fatty acids (LCP) for growth and development of fetal and infant neural tissue, the influence of the dietary n-3 and n-6 LCP intake on the LCP status of forty-three preterm infants (birth weight < 1800 g) was studied. Thirty-one formula-fed infants were randomly assigned to receive a conventional formula lacking LCP (n 16), or an 22:6n-3- and 20:4n-6-enriched formula (n 15); twelve infants received their own mother's breast milk. Fatty acid compositions of plasma and erythrocyte (RBC) phospholipids (PL) were determined in umbilical venous blood, in weekly postnatal samples until day 35 of life and, for the formula-fed infants, at 3 months of corrected age. Both in plasma (P < 0.001) and RBC (P < 0.01) PL, the changes with time until day 35 for 22:6n-3 and 20:4n-6 in the two groups of formula-fed infants were significantly different, with higher values, comparable with those of human-milk-fed infants, in the LCP-enriched-formula group. At 3 months of corrected age, differences between the two formula-fed groups were even more pronounced. In conclusion, adding 22:6n-3 and 20:4n-6 to artificial formulas in balanced ratios and in amounts similar to those found in preterm human milk raises both the 22:6n-3 and the 20:4n-6 status of formulated preterm infants to values found for human-milk-fed preterm infants. Additional studies are necessary to evaluate the potentially favourable effects of this combined addition on the neurodevelopmental outcome of preterm infants.

Arachidonic Acids↗
PubMed1996

Factors predicting differences among general practitioners in test ordering behaviour and in the response to feedback on test requests.

BACKGROUND: In a population of 85 general practitioners diagnostic test ordering behaviour has been changed by means of repeated individual feedback provided since 1985. OBJECTIVES: We studied practitioner and practice characteristics which may explain differences in test ordering behaviour and in the extent to which general practitioners tend to change their behaviour according to the feedback. METHOD: In order to trace such variables, 75 general practitioners were interviewed. In our study request data from individual general practitioners were related to data from several questionnaires. RESULTS: We found no practice characteristics which were of influence on the number of test requests by the general practitioner. Explanatory practitioner characteristics for this were found to be years of experience and working hours per week in practice. CONCLUSIONS: More years of experience as a general practitioner and a shorter duration of consultations correlated with a better response to advice given in the feedback.

Adult↗
PubMed1996

The prevalence of asymptomatic and unrecognized peripheral arterial occlusive disease.

BACKGROUND: The prevalence of peripheral arterial occlusive disease (PAOD), including asymptomatic cases and cases unknown to the general practitioner (GP) was estimated in 18,884 men and women, aged 45-74 years, on the list of 18 general practice centres (GPC). METHODS: The study population (n = 3171) consisted of a stratified sample of the total population. In the GPC data were collected on intermittent claudication (IC), peripheral pulses, vascular risk factors, cardio- and cerebrovascular disease (CCVD) and the ankle brachial systolic pressure ratio (AB ratio) and PAOD was defined as an AB ratio < 0.95 on two consecutive occasions. Results were recalculated for the total population. RESULTS: The prevalence of PAOD was 6.9 percent (95 percent Cl:5.2-7.9 percent), a quarter of which (1.6 percent) met the classic WHO criteria. Peripheral arterial occlusive disease did not occur significantly more often among men than among women but men suffered more often from an advanced stage of PAOD. Of all PAOD cases, 22 percent were symptomatic. The proportion of symptomatic cases correlated positively with higher age, male gender and lower AB ratio. Among asymptomatic PAOD cases the prevelance of concomitant CCVD was three to four times as high as in the group of subjects without PAOD. Of all PAOD cases 68 percent were unknown to the GP and this group mainly represented less advanced cases of atherosclerosis. However, among PAOD cases with an AB ratio <0.75, 42 percent were unknown to the GP. CONCLUSIONS: Our data on asymptomatic and unknown PAOD cases show that GPs can still enhance their efforts towards (secondary) prevention of atherosclerosis.

Adult↗
PubMed1996

A new validated endurance performance test.

The extensive use of performance tests in diet intervention studies mirrors the importance of such a measurement. Although many different endurance performance tests have been used in the past, the majority of these different protocols has never been validated. In this study reproducibility of three different endurance performance tests was evaluated. Thirty well-trained subjects were matched on age, weight, and Wmax and divided into three subgroups. Each group of subjects performed one of three exercise protocols: protocol (A) consisted of cycling at 75% Wmax until exhaustion. In (B) subjects received a preload of 45 min 70% Wmax and then performed as much work as possible in 15 min. (C) consisted of a time trial, in which subjects had to complete a preset amount of work as fast as possible. Each subject performed one of the trials six times. Coefficient of variation (CV) was calculated for each protocol. CV(A) was 26.6%, CV(B) 3.49%, and CV(C) 3.35%. It was concluded that reproducibility of a test at 75% Wmax until exhaustion is poor and these tests are not reliable. Time trial protocols may result in better performance evaluation.

Adolescent↗
PubMed1996

Local corticosteroid injection versus Cyriax-type physiotherapy for tennis elbow.

We performed a prospective, randomised trial on 106 patients to compare the effects of local corticosteroid injections with physiotherapy as advocated by Cyriax in the treatment of tennis elbow. The main outcome measures were the severity of pain, pain provoked by resisted dorsiflexion of the wrist, and patient satisfaction. At six weeks 22 of 53 patients in the injection group were free from pain compared with only three in the physiotherapy group. In the corticosteroid-treated group 26 patients had no pain on resisted dorsiflexion of the wrist compared with only three in the physiotherapy group. Thirty-five patients who had injections and 14 who had physiotherapy were satisfied with the outcome of treatment at six weeks. At the final assessment there were 18 excellent and 18 good results in the corticosteroid group and one excellent and 12 good results in the physiotherapy group. There was a significant increase in grip strength in both groups but those with injections had a significantly better result. After one year there were no significant differences between the two groups. Half of the patients, however, had received only the initial treatment, 20% had had combined therapy and 30% had had surgery. We conclude that at six weeks, treatment with corticosteroid injections was more effective than Cyriax physiotherapy and we recommend it because of its rapid action, reduction of pain and absence of side-effects.

Adult↗
PubMed1995

Anal dynamic graciloplasty in the treatment of intractable fecal incontinence.

BACKGROUND: In patients with intractable fecal incontinence, conventional treatment is not always successful. Dynamic graciloplasty (transposition of the gracilis muscle to the anus with the implantation of stimulating electrodes) was developed to provide such patients with functional neosphincters. We evaluated the clinical results of this new surgical approach and the effects on quality of life. METHODS: We treated 52 patients with dynamic graciloplasty. The clinical results of treatment were evaluated in an interview, by anal manometry, and by enema testing. The degree of continence was scored. To assess quality of life, four questionnaires were administered (parts 1 and 2 of the Nottingham Health Profile, the State-Trait Anxiety Inventory, and the Self-rating Depression scale). RESULTS: Among the 52 patients, 38 (73 percent) were continent after a median follow-up of 2.1 years. At 52 weeks the patients' condition had improved with respect to the median frequency of defecation (from five to two times per 24 hours, P < 0.001), the median time defecation could be postponed (from 9 seconds to 19 minutes, P = 0.012), and the median time an enema could be retained (from 0 to 180 seconds, P = 0.005). Patients in whom the technique was successful became less anxious than those in whom it failed (P = 0.002) and improved with regard to effectiveness in their occupations, ability to perform tasks around the home, personal relationships, sexual function, and social life (P = 0.01). They also became less isolated socially (P = 0.05). CONCLUSIONS: Dynamic graciloplasty is a safe and reliable technique in patients with severe incontinence and may result in a better quality of life.

Adolescent↗
PubMed1995

Randomised controlled trial of routine individual feedback to improve rationality and reduce numbers of test requests.

Feedback can be described as a way to provide information on doctors' performance to enable changes in future behaviour. Feedback is used with the aim of changing test-ordering behaviour. It can lead to reductions in test usage and cost savings. It is not sufficiently clear, however, whether feedback leads to more appropriate test use. Since 1985, the Diagnostic Coordinating Center Maastricht has been giving feedback on diagnostic tests as a routine health care activity to all family doctors in its region. Both quantity and quality of requests are discussed. In a randomised, controlled trial over 2.5 years, discussion of tests not included previously was added to the existing routine feedback. One group of family doctors (n = 39) received feedback on test-group A (electrocardiography, endoscopy, cervical smears, and allergy tests), the other (n = 40) on test-group B (radiographic and ultrasonographic tests). Thus, each group of doctors acted as a control group for the other. Changes in volume and rationality of requests were analysed. The number of requests decreased during the trial (p = 0.036). Request numbers decreased particularly for test-group A (p = 0.04). The proportion of requests that were non-rational decreased more in the intervention than in the control groups (p = 0.009). Rationality improved predominantly for test-group B (p = 0.043). Thus, routine feedback can change the quantity and quality of requests.

Diagnostic Services↗
PubMed1995

Beta-adrenergically mediated thermogenic and heart rate responses: effect of obesity and weight loss.

beta-Adrenergically mediated thermogenic and heart rate (HR) responses, as assessed by stepwise intravenous infusion of the beta-agonist isoprenaline (ISO), were evaluated by partial regression analysis in a group of men with a wide range of body fat (n = 30) and in a subgroup of 16 obese men after weight loss. beta-Adrenergically mediated thermogenesis (open-circuit ventilated-hood system) was blunted in obese subjects, as reflected by a significant positive correlation between percent body fat (hydrostatic weighing) and the plasma ISO concentration needed to increase resting energy expenditure (EE) by 15% (P < .001). The magnitude of the beta-adrenergically mediated HR response was (negatively) associated with the basal plasma norepinephrine (NE) concentration (P < .001). Weight reduction resulted in a significant increase in thermogenic and HR responses in obese subjects. Furthermore, the increase in thermogenic response as a result of weight loss was negatively related to the magnitude of thermogenic response (P < .01) and positively related to the initial percent body fat (P < .05). The increase in HR response as a result of weight loss was positively related to the decrease in basal NE (P < .01) and the change in percent body fat (P < .05). In conclusion, the degree of adiposity was shown to be negatively related to the magnitude of beta-adrenergically mediated thermogenesis, whereas the HR response was merely related to basal NE. Since weight loss resulted in a significant increase in the thermogenic response, the blunted beta-adrenergically mediated thermogenesis does not seem to be a primary factor contributing to the development of obesity.

Adult↗
PubMed1995

Long-chain polyunsaturated fatty acids in preterm infants: status at birth and its influence on postnatal levels.

To determine the influence of the prenatal long-chain polyunsaturated fatty acid (LCP) supply on prenatal growth and on postnatal LCP levels, we studied 52 preterm infants and assessed the relations between the LCP status at birth (reflecting the prenatal LCP supply), gestational age and prenatal growth, and the relation between the LCP status at birth and at 37 to 42 weeks of gestational age. After a correction for gestational age at birth, significant relations (p < or = 0.05) were observed between anthropometric measurements at birth (weight, head circumference, and length) and LCP levels in the umbilical artery wall, the LCP content of which reflects the long-term fetal LCP status. Independent of the neonatal diet (human milk or formula), LCP levels in erythrocyte phospholipids at term were positively related to levels in the umbilical artery wall (docosahexaenoic acid (22:6n-3): p < or = 0.0003; arachidonic acid (20:4n-6): p = 0.02). Postnatal diet significantly influenced LCP levels in plasma phospholipids at term (docosahexaenoic acid: p < or = 0.004; arachidonic acid: p = 0.02); formula-fed infants had lower values. We conclude that the LCP status of preterm infants at birth is related to prenatal growth. Moreover, next to the postnatal enteral diet, the LCP status at birth significantly affects LCP levels at term postconceptional age. This finding may warrant further studies of the effects of essential fatty acid-enriched maternal diets during pregnancy on the neonatal LCP status at birth.

Anthropometry↗
PubMed1995

Long-chain polyene status of preterm infants with regard to the fatty acid composition of their diet: comparison between absolute and relative fatty acid levels in plasma and erythrocyte phospholipids.

The long-chain polyene (LCP) status of thirty-nine premature infants (birth weight < 1800 g) was evaluated. Twenty-seven infants were fed on an artificial formula, twelve received their own mother's breast milk. Fatty acid compositions of both plasma and erythrocyte (RBC) phospholipids (PL) were determined in umbilical venous blood and in weekly postnatal blood samples until the 28th day of life. Individual fatty acid levels were expressed as absolute quantities (mg fatty acid/l plasma or RBC suspension) and as relative (mg/100 mg total fatty acids) values. The changes with time in the absolute values for 22:6n-3 and 20:4n-6 in plasma were strikingly different from those of the relative values for these fatty acids. In plasma PL the inter-group differences in the absolute postnatal values for 22:6n-3 (P < 0.0005) and 20:4n-6 (P < 0.05) and the relative values for 22:6n-3 (P < 0.02) were significant, with lower fatty acid values in the formula-fed infants. In RBC PL, no significant inter-group differences in the postnatal 22:6n-3 and 20:4n-6 values were found. Based on the assumption that it is desirable for formula-fed infants to achieve postnatal plasma LCP values at least comparable with those found in infants fed on human milk, the findings of the present study indicate that both n-3 and n-6 LCP should be added to preterm infant formulas. Moreover, the additional importance of absolute fatty acid levels was demonstrated, although analytical procedures need to be standardized to enable effective comparison of results from different research groups.

Dietary Fats↗
PubMed1995

Maternal essential fatty acid patterns during normal pregnancy and their relationship to the neonatal essential fatty acid status.

Although essential fatty acids (EFA) and their longer chain, more unsaturated derivatives play a major role during pregnancy, hardly any information is available with respect to the course of the maternal EFA status during an uncomplicated pregnancy and its relationship to the neonatal EFA status. Therefore, a longitudinal study was started in which 110 pregnant women gave repeated blood samples from the 10th week of gestation until delivery. After birth a blood sample from the umbilical vein and a maternal venous blood sample were collected as well, and 6 months after delivery a final blood sample from the mother was taken. The absolute (mg/l) and relative (% total fatty acids) amounts of the fatty acids in plasma phospholipids were determined. The total amounts of fatty acids increased significantly during pregnancy. This pattern was similar for the individual fatty acids and fatty acid families. The relative amount of linoleic acid (18:2n-6) did not change during pregnancy, whereas the relative amount of arachidonic acid (20:4n-6) decreased. Despite maternal mobilization of docosahexaenoic acid (22:6n-3, DHA), suggested by a temporary increase in the DHA status until 18 weeks gestation, the DHA status steadily declined thereafter. This pattern was associated with a progressive increase in the DHA deficiency index in maternal blood throughout pregnancy and resulted in a sub-optimal neonatal DHA status. The overall maternal EFA status also declined steadily during pregnancy. Therefore, the question arises whether the mother, under the prevailing dietary conditions, is able to meet the high fetal requirement for EFA.

Adult↗