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Biomedical subjects

G Visser

Publications and source records attributed to G Visser.

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

Succinyl-CoA:acetoacetate transferase deficiency: identification of a new patient with a neonatal onset and review of the literature.

UNLABELLED: We describe the clinical symptoms and biochemical findings of a patient with succinyl-CoA:acetoacetate transferase deficiency who presented in the neonatal period and review the current literature on this subject. Our patient was initially suspected to have distal renal tubular acidosis, and subsequently, a fasting test revealed severe metabolic ketoacidosis with normal blood glucose after 13 h which suggest a defect in ketolysis. In his cultured skin fibroblasts succinyl-CoA:acetoacetate transferase was deficient (residual activity 15%). Treatment in the acute phase consisted of sodium bicarbonate. At the present age of 9 years, psychomotor and physical development are within normal limits. CONCLUSION: Defects of ketolysis probably are underdiagnosed disorders and should be considered in infants and young children with persistent ketosis.

Acetoacetates↗
PubMed1996

Evidence for genetic heterogeneity in the carbohydrate-deficient glycoprotein syndrome type I (CDG1).

We have analyzed a series of polymorphic markers on chromosome 16p13 in 17 families with carbohydrate-deficient glycoprotein syndrome type I (CDG1). First, linkage to the region between D16S406 and D16S500 is confirmed. The telomeric border of the candidate region is now definitively placed proximal to D16S406 by crossovers observed in 2 families. Second, in 1 family with 2 affected siblings, the disease is not linked to chromosome 16p. Genetic heterogeneity has not been previously reported for CDG1, and this observation has implications for prenatal diagnosis. Third, allelic associations suggest that the disease locus is localized close to D16S414/D16S497. This places the region of interest centromeric of its published localization.

Chromosomes, Human, Pair 16↗
PubMed1996

Neurotransmitter positron emission tomographic-studies in adults with phenylketonuria, a pilot study.

Patients with phenylketonuria (PKU) may suffer from cognitive and neurological deficits which are related to reduced intracerebral concentrations of catecholamines. The function of phenylalanine (Phe) as an inhibitor of the uptake of the precursor amino acid tyrosine (Tyr) through the blood-brain barrier as well as an inhibitor of the expression of dopamine receptors in the brain is under investigation. Positron emission tomography (PET) is a method for quantitatively determining biochemical and physiological processes in vivo. In the current pilot study, L-[1-11C]-Tyr and 18F-fluoro-ethyl-spiperone (FESP) have been used. The metabolic pathway of carboxylic labelled Tyr is mainly incorporation into protein. From the measured tissue and plasma activity as a function of time in combination with a compartimental model the Protein Synthesis Rate (PSR) for Tyr can be calculated. FESP is a ligand which binds irreversibly to the dopamine D2-receptor and has also a low non specific binding, although affinity to the serotonin receptor has been described. The ratio of FESP concentration in striatum and in cerebellum is a measure of the receptor status in vivo. In patients with plasma Phe levels above the maximum therapeutic concentration (> 700 mumol/l) the PSR for Tyr was decreased as compared to controls and patients with plasma Phe concentrations within the therapeutic range, indicating a decreased availability of Tyr for neurotransmitter synthesis, and hence explaining the reduced cerebral concentration of catecholamines.

Adolescent↗
PubMed1995

Intracranial tuberculosis in The Netherlands: four paediatric cases.

UNLABELLED: Since 1987 a resurgence of tuberculosis is occurring in the Netherlands in analogy to the situation in other industralised countries. So far this has not been associated with an increased incidence of tuberculous meningitis, which is still a rare complication of the disease. Four cases of intracranial tuberculosis were recently diagnosed in our hospital. All children were from middle-class Dutch families with no identified risk for tuberculosis. An extensive contact identification search could identify a contact in two patients. Two children were in an advanced stage of disease before diagnosis. Skin tests were repeatedly negative in all cases which delayed treatment in two cases for almost 2 weeks. One patient developing a cerebral tuberculous focus during therapy responded well to a second course of corticosteroids. Three children developed severe neurological sequelae. CONCLUSION: This report illustrates that suspicion of intracranial tuberculosis is warranted in the case of an ill-defined inflammatory neurological syndrome.

Antitubercular Agents↗
PubMed1994

Reduction of intratumoral pH by the mitochondrial inhibitor m-iodobenzylguanidine and moderate hyperglycemia.

The interstitial pH of RIF-1 tumors was selectively lowered by i.p. administration of the mitochondrial inhibitor meta-iodobenzylguanidine (MIBG; 40-100 mg/kg), supported by sustained moderate hyperglycemia (plasma glucose concentration, 14 mM) in rats or by a single i.p. bolus injection of glucose (1.5 g/kg) in mice. Responses were evaluated in a multicenter study by pH measurements with semimicroelectrodes and 31P magnetic resonance spectroscopy, by biochemical analysis of tissue and plasma levels of glucose and lactate, and by positron emission tomography analysis of 2-[18F]fluoro-2-deoxy-D-glucose uptake. In both schedules, treatment with MIBG and glucose reduced the mean intratumoral pH as recorded with semimicroelectrodes to 6.2. In the mouse model, treatment with MIBG plus glucose was accompanied by a 2-3-fold stimulation of 2-[18F]fluoro-2-deoxy-D-glucose uptake and a corresponding increase in tumor glucose content. Responses were maximal in male mice with tumors of 0.2-0.8 g. 31P magnetic resonance spectroscopy analysis revealed no changes in intracellular pH or metabolic status, indicating that only extracellular pH was affected. MIBG was synergistic with bolus or continuous glucose administrations by a dual mechanism. The drug reduced by up to 5-fold the amount of glucose required for effective reduction of intratumoral pH and promoted the availability of (extra) glucose to tumor tissue in a stress-related, sympathomimetic response. Moreover, by converting oxic tumor cells into functionally hypoxic cells, combined treatment resulted in a more homogeneous decrease in intratumoral pH which included better perfused peripheral tumor areas. The effects of combined treatment on tumor glucose metabolism could be monitored noninvasively by 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography analysis.

3-Iodobenzylguanidine↗
PubMed1994

The 1992 measles epidemic in Cape Town--a changing epidemiological pattern.

Over the last 6 years there has been a decline in the incidence of measles in Cape Town. However, during August 1992 an outbreak occurred, with cases reported at many schools in children presumably immunised. The objectives of this study were to characterise the epidemic in Cape Town and to determine possible reasons for the outbreak. The investigation consisted of two components--a description of the epidemic and an investigation of an outbreak at one primary school. Results indicate that during the last 4 months of the year, 757 cases were notified in Cape Town, compared with 144 in the first 8 months. The epidemic affected mainly white and coloured children over 5 years of age (P < 0.001). In contrast, during the period before the epidemic most cases occurred in black children and in those aged less than 1 year (P < 0.001). There was no significant increase in hospitalised cases. Investigation of the outbreak at one school revealed that the attack rate was 7.6% (25/329 children). Immunisation coverage (at least one dose of any measles vaccine) was 91% and vaccine efficacy was estimated to be 79% (95% CI 55-90); it was highest for monovalent measles (100%) and lowest for measles-mumps-rubella (74%). The epidemiology of measles in Cape Town has thus changed as evinced in this epidemic, with an increase in the number of cases occurring in older, previously vaccinated children. The possible reasons for this include both primary and secondary vaccine failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Quality requirements in nursing departments: development and use of a general framework.

The nursing staff of the Nijmegen University Hospital has implemented a project to formulate and evaluate objectives of quality of care. A quality profile, formulated on a national level, has been used as a guide in quality projects at nursing units for four years. The results of these quality projects show a lot of definite quality improvements and also a large number of quality requirements. In 1991 an inventory was made of these requirements. A specific method was used to select these requirements. Finally, a new framework of quality requirements was formulated. This framework offers the Nijmegen University Hospital possibilities such as: (i) being a source from which targets may be selected for quality improvement projects; (ii) requirements being made operational and used to measure the quality of nursing care.

Hospitals, University↗
PubMed1990

Oscillations in cell morphology and redox state.

Fluctuations in the intensity of light scattered and absorbed by cells in suspension have been analysed by smoothing, periodogram and power spectrum methods to reveal oscillations attributed to changes in cell morphology and the redox state of NADH and FAD (periods 10 s to 30 min). The rhythms are themselves periodically modulated in amplitude at a similar frequency and exhibit burst characteristics. The low frequency scatter dynamics are provisionally attributed to oscillations in gross morphology and the high frequency variation to changes at the cell surface. Agents, such as insulin and transferrin, affect the dynamics. The scatter results suggest that rhythmic changes in cell morphology associated with locomotion are largely inherent in the cell and not due to periodic attachment and detachment from a surface.

Animals↗