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Biomedical subjects

A M Kamper

Publications and source records attributed to A M Kamper.

14 recordsLinked to original sources
PubMed2002

Testing cognitive function in elderly populations: the PROSPER study. PROspective Study of Pravastatin in the Elderly at Risk.

OBJECTIVES: For large scale follow up studies with non-demented patients in which cognition is an endpoint, there is a need for short, inexpensive, sensitive, and reliable neuropsychological tests that are suitable for repeated measurements. The commonly used Mini-Mental-State-Examination fulfils only the first two requirements. METHODS: In the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), 5804 elderly subjects aged 70 to 82 years were examined using a learning test (memory), a coding test (general speed), and a short version of the Stroop test (attention). Data presented here were collected at dual baseline, before randomisation for active treatment. RESULTS: The tests proved to be reliable (with test/retest reliabilities ranging from acceptable (r=0.63) to high (r=0.88) and sensitive to detect small differences in subjects from different age categories. All tests showed significant practice effects: performance increased from the first measurement to the first follow up after two weeks. CONCLUSION: Normative data are provided that can be used for one time neuropsychological testing as well as for assessing individual and group change. Methods for analysing cognitive change are proposed.

Aged↗
PubMed2001

Forearm blood flow measurements using computerized R-wave triggered strain-gauge venous occlusion plethysmography: unilateral vs. bilateral measurements.

The human forearm is a well established model to study local vascular reactivity in humans in vivo, using strain-gauge venous occlusion plethysmography to measure blood flow and changes in blood flow in the forearm. To reduce the intra-individual variability of the forearm blood flow (FBF), it has been advocated that simultaneous measurements of contralateral forearm blood flow is obligatory. Therefore, the use of the calculated forearm ratio (FR) is recommended instead of using the actual FBF. In the present study we compared the intra-individual variability of forearm blood flow measurements and the forearm ratio, by using computerized R-wave triggered strain-gauge venous occlusion plethysmography, to test if bilateral expression of measurements is better than unilateral. Results were obtained in eight volunteers. Intra-arterial infused sodium nitroprusside induced a dose dependent increase in forearm blood flow and a dose dependent increase in the calculated forearm ratio. Intra-arterial infused norepinephrine induced a dose dependent decrease in forearm blood flow and a dose dependent decrease in the calculated forearm ratio. The differences between the variation coefficients of the forearm blood flow measurements and the calculated forearm ratio were different. These results support our hypothesis that by using a computerized, R-wave triggered system for unilateral forearm blood flow measurement is a more reliable outcome than the calculated forearm ratio derived from bilateral measurements.

Adult↗
PubMed2001

Effect of simvastatin on renal function in autosomal dominant polycystic kidney disease.

BACKGROUND: In animal models, HMG-CoA reductase inhibitors were able to improve renal function and endothelium-dependent vascular reactivity. In various experimental renal diseases, including autosomal dominant polycystic kidney disease (ADPKD), HMG-CoA reductase inhibitors improved the rate of decline in renal function. We studied the effect of simvastatin on ADPKD patients. METHODS: In a double-blind cross-over study, 10 normocholesterolaemic ADPKD patients were treated in random order for 4 weeks with 40 mg simvastatin or placebo daily. After each treatment period, we investigated the effect of simvastatin on renal blood flow and endothelium-dependent vascular reactivity. These periods were separated by a 4-week wash-out period. RESULTS: After treatment with simvastatin, glomerular filtration rate (GFR) significantly increased from 124+/-4 ml/min to 132+/-6 ml/min (P<0.05). Simultaneously, effective renal plasma flow (ERPF) increased significantly from 494+/-30 ml/min to 619+/-67 ml/min after simvastatin treatment (P<0.05). These renal effects were accompanied by a significantly enhanced vasodilator response to acetylcholine in the forearm after simvastatin treatment. Total serum cholesterol levels were significantly reduced after treatment with simvastatin, from 4.24+/-0.32 to 3.17+/-0.22 mmol/l (P<0.001). CONCLUSION: We concluded that simvastatin treatment can ameliorate renal function in ADPKD patients, by increasing renal plasma flow, possibly via improvement of endothelial function. Long-term clinical trials with HMG-CoA reductase inhibitors are needed to confirm these results and to establish a chronic inhibiting effect of HMG-CoA reductase inhibitors on the progression towards end-stage renal disease in ADPKD patients.

Acetylcholine↗
PubMed2001

Bezafibrate reduces heart rate and blood pressure in patients with hypertriglyceridemia.

OBJECTIVE: In hypertriglyceridemic patients, hypertension occurs frequently and may be associated with hyperinsulinemia and elevated plasma levels of free fatty acids (FFA). Besides the lipid-lowering effects, fibrates have been shown to reduce blood pressure in hypertensive patients. The present study was undertaken to investigate the effects of bezafibrate on hemodynamics in relation to insulin, FFA, sympathetic activity, renal sodium absorption, cyclic-GMP (cGMP) and endothelin-1 in hypertriglyceridemic patients. SUBJECTS AND METHODS: Hypertriglyceridemic patients (17) were randomized to receive in a double-blind placebo-controlled study bezafibrate or placebo for 6 weeks. At the end of both treatment periods, blood pressure and heart rate were measured automatically. Plasma insulin, FFA, aldosterone, catecholamines, cGMP, endothelin-1 levels and 24 h urine catecholamines and sodium excretion were assessed. RESULTS: Bezafibrate therapy decreased serum triglycerides (-65%, P < 0.001) and hemodynamic parameters: heart rate decreased from 69 to 66/min (P = 0.009), systolic blood pressure from 137 to 132 mmHg (P = 0.01), diastolic blood pressure from 81 to 79 mmHg (P = 0.07) and mean blood pressure from 102 to 99 mmHg (P = 0.06). Bezafibrate therapy reduced FFA and insulin (-55 and -57% respectively, both P < 0.001), while sympathetic activity and renal sodium absorption were not affected. cGMP increased (+17%, P = 0.008), whereas endothelin-1 levels tended to decrease upon bezafibrate therapy (-10%, P = 0.077) CONCLUSION: Bezafibrate reduces heart rate, blood pressure, insulin and FFA in hypertriglyceridemic patients. The hemodynamic effects cannot be attributed to changes in sympathetic activity or renal sodium absorption. Instead, based on the increase in plasma cGMP levels, the bezafibrate-induced hemodynamic effects are most likely to be caused by bezafibrate-induced improvement of endothelial function.

Absorption↗
PubMed2000

The angiotensin-converting enzyme gene polymorphism and responses to angiotensins and bradykinin in the human forearm.

The deletion (D) allele of the angiotensin-converting enzyme (ACE) is associated with high ACE levels. Subjects homozygous for the D allele should therefore exhibit enhanced angiotensin I-induced vasoconstrictor responses and diminished bradykinin-induced vasodilator responses as compared with subjects homozygous for the insertion (I) allele. In eight II and eight DD normotensive male subjects, angiotensin I, bradykinin, and angiotensin II were infused in the forearm. Changes in forearm blood flow were registered with venous occlusion plethysmography. Blood was sampled to quantify angiotensin I to II conversion. Plasma ACE levels were 60% higher, and DD subjects showed an enhanced response to angiotensin I infusion (p < 0.05). No differences in angiotensin I to II conversion, angiotensin H vasoconstriction, and bradykinin vasorelaxation were found. The ACE-inhibitor enalaprilate inhibited angiotensin I-induced vasoconstriction, but did not significantly affect bradykinin-induced vasodilation. The AT1-receptor antagonist losartan (3,000 ng/kg/min) inhibited angiotensin II-induced vasoconstriction. In conclusion, subjects with the DD genotype display an enhanced vasoconstrictor response to angiotensin I, which cannot be explained on the basis of a similarly enhanced angiotensin I to II conversion rate or a difference in vascular reactivity. Possibly therefore, differences in angiotensin I to II conversion occur within the vascular wall only, at a site that does not readily equilibrate with blood plasma.

Adult↗
PubMed1999

Effects of arm dominance and brachial artery cannulation on forearm blood flow measured by strain-gauge plethysmography.

The human forearm model is used extensively in physiological, pharmacological and clinical investigations. Effects of arm dominance or arterial cannulation on forearm flow measurements have never been tested formally. In the present study we tested the hypotheses that left or right arm dominance or cannulation of the brachial artery do not affect forearm haemodynamic responses to physiological or pharmacological stimuli. Results obtained in 16 volunteers showed that forearm blood flow responses to physiological stimuli are comparable before and after intra-arterial cannulation in either the dominant or the non-dominant forearm. Cannulation of a forearm brachial artery has a small effect on baseline blood flow. Responses to intra-arterially infused noradrenaline (norepinephrine) were not influenced by left or right arm dominance. Intravenous infusion of noradrenaline in eight subjects resulted in small responses in forearm blood flow that were slightly asymmetrical. During the intravenous infusion of noradrenaline, forearm blood flow or the forearm blood flow ratio did not reflect the marked increase in FVR that occurred. These results support our hypotheses (a) that either arm can be used as the control or intervention arm, and (b) that intra-arterial cannulation does not affect the results of intra-arterial infusion studies.

Adult↗
PubMed1998

Chronic hepatitis B and neurogenic muscle disease: case report.

A 17 year-old boy with chronic hepatitis B who developed left-sided muscle wasting is reported. When other possible known diseases as the cause of the neurogenic muscle disease were excluded it was hypothesised that there was a relation between the chronic hepatitis B infection and the neurogenic muscle disease. An immunopathogenesis could be explained by the presence of HBsAg in the cerebral spinal fluid.

Adolescent↗
PubMed1996

Endoscopic treatment of biliary ascariasis. Report of a case.

Ascaris lumbricoides is the most common intestinal parasite to infect humans. The incidence of ascariasis is increasing in our regions, due to world travel and population migration. In one third of cases, the worm can enter the bile duct and cause cholangitis or biliary colics. Diagnosis and treatment of ascariasis are discussed. Endoscopic retrograde cholangio-pancreaticography (ERCP) with endoscopic extraction of the worm, using a Dormia basket, is a safe and effective procedure for the diagnosis and treatment of biliary ascariasis. This technique serves as an effective alternative for surgery.

Animals↗
PubMed1994

Parvovirus infection causing red cell aplasia and leukopenia in rheumatoid arthritis.

A case of acute parvovirus B19 infection causing fever, anaemia, leukopenia, and red cell aplasia, in a patient with chronic rheumatoid arthritis is described. The patient had received low doses of corticosteroids for several years, and a small dose of methotrexate recently. There was no evidence of haemolytic anaemia, iron deficiency or drug toxicity. Recovery was associated with the development of antibodies against parvovirus B19, and clearance of viraemia as detected by the polymerase chain reaction. Possible mechanisms for the development of leukopenia are discussed, but there was no evidence for haemophagocytosis.

Arthritis, Rheumatoid↗
PubMed1994

Filum terminale ependymoma revealed by acute cauda equina compression syndrome following intratumoral and spinal subarachnoid hemorrhage in a patient on oral anticoagulants.

A 65 year-old woman with a filum terminale ependymoma is reported, presenting with acute cauda equina compression syndrome due to intratumoural and subsequent spinal subarachnoid hemorrhage (SAH) following therapy with oral anticoagulants. Few cases of spinal ependymoma have been reported with an acute cauda equina compression syndrome as the initial and only symptom, and the unique feature of our patient's anticoagulant status has only been described once in this setting. Although intratumoural hemorrhage is very well known since the myxopapillary variant is unique to the cauda equina and consists of loose connective tissue and numerous small blood vessels that are prone to bleeding, spinal SAH is seldom seen and the different hypotheses about the pathophysiological mechanisms that might promote bleeding still remain unresolved and will be discussed in this paper, as well as the special clinical features of spinal SAH and some diagnostic and therapeutic implications. A review of the literature (Medline search 1983-1993) revealed only 13 cases, including ours, of spinal SAH due to cauda equina ependymoma, and the results of this review together with our findings are described in this paper.

Acute Disease↗