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Biomedical subjects

E Dekker

Publications and source records attributed to E Dekker.

At least 37 records · Page 2Linked to original sources
PubMed1997

Glucose production and gluconeogenesis in adults with uncomplicated falciparum malaria.

Although glucose production is increased in severe malaria, the influence of uncomplicated malaria on glucose production is unknown. Therefore, we measured in eight adult Vietnamese patients with uncomplicated falciparum malaria and eight healthy Vietnamese controls glucose production (by infusion of [6,6-2H2]glucose) and the fractional contribution of gluconeogenesis (by oral ingestion of 2H2O); glycogenolysis was calculated as the difference between the two. After 20 h of fasting, plasma glucose was 4.7 +/- 0.2 mmol/l in the patients and 4.3 +/- 0.2 mmol/l in the controls (not significant). Glucose production was approximately 25% higher in the patients (16.9 +/- 1.3 vs. 13.4 +/- 0.3 mumol.kg-1.min-1, P = 0.01). Fractional and absolute gluconeogenesis were increased in the patients (approximately 87 vs. approximately 59%, P < 0.001; and 14.6 +/- 1.3 vs. 7.9 +/- 0.2 mumol.kg-1.min-1, P < 0.001, respectively). The contribution of glycogenolysis to total glucose production was decreased in the patients: 2.3 +/- 0.5 vs. 5.5 +/- 0.4 mumol.kg-1.min-1 (P < 0.002). In conclusion, in adult patients with uncomplicated falciparum malaria, glucose production is increased by approximately 25% due to an increased rate of gluconeogenesis, whereas glycogenolysis is decreased. The mechanism by which these changes occur is uncertain. However, counterregulatory hormone and cytokine concentrations were increased in the patients.

Adult↗
PubMed1997

Glucose homeostasis in children with falciparum malaria: precursor supply limits gluconeogenesis and glucose production.

To evaluate glucose kinetics in children with falciparum malaria, basal glucose production and gluconeogenesis and an estimate of the flux of the gluconeogenic precursors were measured in Kenyan children with uncomplicated falciparum malaria before (n = 11) and during infusion of alanine (1.5 mg/kg.min; n = 6). Glucose production was measured by [6,6-2H2]glucose, gluconeogenesis by mass isotopomer distribution analysis of glucose labeled by [2-13C]glycerol. Basal plasma glucose concentration ranged from 2.1-5.5 mmol/L, and basal glucose production ranged from 3.3-7.3 mg/kg.min. Glucose production was largely derived from gluconeogenesis (73 +/- 4%; range, 52-93%). During alanine infusion, plasma glucose increased by 0.4 mmol/L (P = 0.03), glucose production increased by 0.8 mg/kg.min (P = 0.02), and gluconeogenesis increased by 0.8 mg/kg.min (P = 0.04). We conclude that glucose production in children with uncomplicated falciparum malaria is largely dependent on gluconeogenesis. However, gluconeogenesis is potentially limited by insufficient precursor supply. These data indicate that in children with falciparum malaria, gluconeogenesis fails to compensate in the presence of decreased glycogen flux to glucose, increasing the risk of hypoglycemia.

Alanine↗
PubMed1996

Survival and aortic events after graft replacement for thoracoabdominal aortic aneurysm.

Graft replacement remains the procedure of choice for patients with thoracoabdominal aortic aneurysm. Since there is little information regarding the long-term survival following these major vascular operations which may carry a risk of various late complications, a retrospective analysis of 10 years follow-up was undertaken. The results of 172 consecutive operations for thoracoabdominal aortic aneurysm were analysed retrospectively. Hospital mortality rate was 10.5%. Temporary postoperative haemodialysis was necessary in 10.4% of cases and paraplegia occurred in 8.2%. The mean (s.e.) overall cumulative 2-, 5- and 10-year observed survival rate was 76(3.4), 53(4.5) and 19(7)%, respectively while expected survival of a background population at 2, 5 and 10 years was 94%, 85% and 71%, respectively. Reoperation for an early (< 7 days) or late (> 7 days) aortic event was necessary in 31 patients. If performed electively, the hospital mortality rate for late aortic reoperation was only 7% but an emergency reoperation, hospital mortality rate was 100%.

Aged↗
PubMed1995

Analysis of risk factors for excess mortality after aortic valve replacement.

OBJECTIVES: This study sought to identify risk factors for both late observed and late "excess" mortality after aortic valve replacement and to examine the causes of late mortality. BACKGROUND: Because operative mortality after aortic valve replacement is very low, the timing of surgical intervention should focus on maximizing long-term survival. However, to judge the effect of valve replacement on long-term survival in an elderly population, it is important to separate mortality resulting from extraneous causes (background mortality) from disease-related mortality (excess mortality). Background mortality can be estimated by calculating expected mortality on the basis of age and gender. METHODS: From 1966 to 1986, 643 patients (mean age 59.6 years, 138 [21%] > or = 70 years old) underwent aortic valve replacement, 129 of whom also underwent coronary bypass grafting; 594 patients survived > or = 30 days after the procedure. The overall operative mortality rate for isolated aortic valve replacement decreased over time from 25.5% (1966 to 1972) to 2.6% (1980 to 1986). Cumulative total follow-up after discharge was 3,603 patient-years. Multivariate analysis was performed for both observed and excess mortality. RESULTS: Risk factors for both observed and excess mortality were previous myocardial infarction, coronary artery disease, heart failure and atrial fibrillation. Although age > or = 70 years was a risk factor for observed mortality (hazard rate ratio [HRR] 2.4, 95% confidence interval [CI] 1.6 to 3.7), it was not a risk factor for excess mortality. In contrast, isolated aortic regurgitation was an important risk factor for excess mortality only (HRR 3.8, 95% CI 1.3 to 11.2). Late mortality was valve related in 22% of patients, including sudden death in 7% and cerebral vascular accidents in 7%. Congestive heart failure was an important cause of death (21%) irrespective of the time elapsed since aortic valve replacement. In patients with aortic regurgitation, congestive heart failure was the main cause of death (38%); in patients with aortic regurgitation and preoperative heart failure or severe left ventricular dysfunction, heart failure was the cause of death in 44% and 63%, respectively. CONCLUSIONS: Analysis of excess mortality revealed that older age in itself is not a risk factor for late mortality after aortic valve replacement. Aortic regurgitation carries a high risk, probably associated with left ventricular dysfunction at the time of operation. Earlier operation may be warranted in such patients.

Age Factors↗
PubMed1993

Background mortality in clinical survival studies.

In long-term follow-up studies of survival after an initial event (eg, an operation) mortality from causes other than the one under study obscures the results, especially in elderly patients. In the traditional approach to the calculation of expected mortality a fictitious cohort is drawn from the general population, being matched for age, sex, and calendar time at the time of the initial event. The membership of this cohort is then kept constant from the initial event until the closing date of the study. The survival and mortality of this static cohort is then compared with that of the dynamic patient cohort to throw light on mortality from extraneous causes. This method can lead to severe bias if there is a strong correlation between the duration of observation of the patients and their age. The analysis can be improved by applying rate adjustment when calculating the background component of mortality. In this approach mortality rates from the general population are adjusted (weighted) so that the age, sex, and calendar year are at all times identical with those of each of the patients still alive and under observation. This is illustrated by means of a simplified example and a real-life one from a study at survival after aortic valve replacement. Estimation of rate-adjusted background mortality provides a framework that may put long-term survival, especially of elderly patients, in proper perspective.

Adult↗
PubMed1992

Low-molecular-weight heparin versus standard heparin in general and orthopaedic surgery: a meta-analysis.

Low-molecular-weight heparins (LMWHs) have theoretical advantages over standard heparin as postoperative thromboprophylactic agents. We conducted a meta-analysis of studies reported between 1984 and April, 1991, in which LMWHs were compared with standard heparin for postoperative prophylaxis. We included only randomised studies (reported in English, French, or German) in which investigators compared currently recommended doses of the agents and used adequate screening techniques for deep vein thrombosis. For all surgical studies the relative risk (LMWH versus standard heparin) for deep vein thrombosis was 0.74 (95% Cl 0.65-0.86), for pulmonary embolism 0.43 (95% Cl 0.26-0.72), and for major bleeding 0.98 (95% Cl 0.69-1.40). Comparable relative risks were observed for the general and orthopaedic surgery studies separately. When the analysis for the general surgery studies was limited to those of strong methodology, assessed by eight criteria defined in advance, the benefit/risk ratio was less favourable--relative risk for deep vein thrombosis 0.91 (95% Cl 0.68-1.23), for major bleeding 1.32 (95% Cl 0.69-2.56). There is at present no convincing evidence that in general surgery patients LMWHs, compared with standard heparin, generate a clinically important improvement in the benefit to risk ratio. However, LMWHs may be preferable for orthopaedic surgery patients, in view of the larger absolute risk reduction for venous thrombosis.

Clinical Trials as Topic↗
PubMed1991

Transesophageal atrial pacing--stimulation and discomfort thresholds: the role of electrode configuration and pulse width.

A balloon catheter with six electrodes has been developed for transesophageal atrial stimulation of the human heart. Introduction is easy and its positioning is simple with the help of six unipolar atrial electrograms. In a group of 20 healthy volunteers, stimulation and discomfort thresholds (intolerable discomfort) were measured for three levels of pulse widths (12, 16, and 20 msec) and for five electrode configurations. Stimulation thresholds were below discomfort thresholds in each case. The stimulation threshold depended on pulse width and not on electrode configuration. The discomfort threshold, however, depended on the electrode configuration and not on the pulse width. A moderate but potentially important increase of the ratio between stimulation threshold and discomfort threshold could be achieved by combining a long pulse width (20 msec) and avoiding the largest distance between the active (cathode) and the passive (anode) electrode. Transesophageal atrial stimulation promises to be a practical noninvasive tool for the termination of regular supraventricular tachycardias, basal electrophysiological studies, and controlled acceleration of the heart rate in the study of myocardial ischemia.

Adult↗
PubMed1989

[HIV occupational risk of surgical specialists and operating room personnel in the Saint Lucas Hospital in Amsterdam].

All instrument and needle accidents, and mucosal exposure to blood involving surgical specialists and operating room personnel were recorded for a seven-month period in a middle-sized Amsterdam hospital, the St. Lucas. Fifty-four accidents were reported, of which 42 were percutaneous wounds and 12, blood splatters in the eyes. The frequency of percutaneous wounds per operation per person ranged from 0 to 0.013. In the same period 3098 patients who had to be operated on were asked to participate in an anonymous study for HIV antibody. One hundred and twenty patients refused participation (3.9%). Of the 2978 participating patients seven were seropositive for anti-HIV (0.23%). The observed percutaneous accident frequency and HIV prevalence were used in combination with reports from the literature on the risk of infection after a single exposure to HIV infected material, to calculate the HIV professional risk for operating room personnel in this hospital. For general surgeons the risk of infection (based on 500 operations per year) was calculated as 0.0012 for an occupational lifespan of 30 years. For the other specialists and functions the risk was the same or less. Considering the low risk our conclusion is that screening of preoperative patients is not necessary in this hospital. The observance of general protective measures provides sufficient protection for the professional group examined.

Accidents↗
PubMed1987

Health policy and mental health.

Health policy can be described as policy directed at the determinants of health, i.e. biological and environmental factors, lifestyle and the health care system. This type of policy now has become a policy objective in an increasing number of countries. In this article mental health is placed in the broad context of this policy. The central question is: can the mental health field grasp the opportunity of a growing interest in prevention and health promotion in general, as major objectives of health policy? Or will it stay more or less isolated from the mainstream of current developments? Answering this question means looking at the conditions of health policy. For health policy it is required that a definition be given of health problems and "causing" conditions. There should further be available intervention possibilities of a preventive and intersectoral character and also preventive strategies. It is stated that there is enough standardized information on mental health problems and experience with community-based research to let mental health participate in drawing up a community diagnosis. It also appears possible to construct an ecological health status model for mental health. Research on the factors in this model shows a shift in focus from risk populations to risk situations, e.g. unemployment, industrial disability, divorce and isolation. Further it is recognized that the search for causal factors is substituted by that for precipitating factors. Social-demographic factors, taken alone, are not precipitating factors. What matters is the combination of an underdeveloped coping mechanism, little social support, and prolonged stressful conditions or sudden stressful events.(ABSTRACT TRUNCATED AT 250 WORDS)

Europe↗
PubMed1982

Practical considerations in the positioning of EEG electrodes.

Although the 10-20 system of the International Federation was originally proposed as a basis for discussion, there has been little published comment on its strengths and weaknesses or suggestions for its improvement. There are inherent ambiguities in the system, which cannot be applied strictly in accordance with the published specification unless the 4 measurements between the right and left preauricular points and the nasion and the inion are all equal. A study of the cranial measurements of 20 normal adults showed that this criterion was fulfilled to within a margin of 10% in less than half. Further, the standard placements of the 10-20 system cover less than 3/4 of the cerebral convexity. A study of fronto-temporal epileptiform phenomena in 100 subjects indicated that in the majority these were of maximum amplitude over the anterior temporal region, some 20 mm below the typical positions of F7 and F8. In the light of these and previous studies, modifications of the 10-20 system are suggested.

Adult↗
PubMed1980

[Improved care for the aphasic patient: introduction to the central theme of aphasia].

The Dutch Hart Foundation has as one of its major goals the furthering of revalidation of hart patients as well as patients with cerebrovascular illnesses. Since many of these latter patients suffer from aphasic disturbances, the CVD-committee of the above mentioned foundation has, in co-operation with the Dutch Society for Neurology, investigated the possibilities of improving the treatment of these disturbances. A systematic improvement of this treatment depends on the ability to measure it. Therefore, the foundation has invited a number of prominent researchers in this area for a workshop in August 1979 posing the question whether and if so how the severity of aphasia can be measured. The lectures of this meeting, including the discussion, are published in this issue.

Aged↗