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Biomedical subjects

H W van Hamersvelt

Publications and source records attributed to H W van Hamersvelt.

At least 19 recordsLinked to original sources
PubMed2005

[A genetic childhood disease with consequences in adult life: the Denys-Drash syndrome].

In a 17-year-old woman with absent sexual development and a congenital nephrotic syndrome leading to renal failure, the Denys-Drash syndrome was diagnosed after development of an ovarian dysgerminoma. The Denys-Drash syndrome is characterised by the triad: progressive nephropathy due to diffuse mesangial sclerosis, male pseudo-hermaphroditism (XY karyotype with ambiguous or female genital organs) and an increased risk of developing Wilms' tumour and gonadoblastoma. The syndrome is generally caused by a genetic defect in the Wilms' tumour suppressor 1 gene (WT1 gene). A WT1 mutation and XY karyotype were also found in this patient. The WT1 gene encodes a transcription factor playing an important role in renal and genital development. The diagnosis of Denys-Drash syndrome had important consequences for the follow-up and treatment of the patient. The second gonad and the native kidneys were removed due to the increased risk of malignancy. Moreover, the finding of a XY karyotype could result in serious psychic problems. Physicians responsible for the health of adults are confronted more and more often with the consequences of childhood diseases. This case illustrates the necessity to inform such physicians about previously untreatable genetic diseases of childhood so that the adequate medical management of these patients can be guaranteed.

Adolescent↗
PubMed2003

Two cases of subcutaneous Scedosporium apiospermum infection treated with voriconazole.

Scedosporium apiospermum is a mold that is increasingly being recognized as an opportunistic pathogen in immunocompromised patients, and treatment is complicated by intrinsic resistance to several antifungal agents. In our hospital, two cases of S. apiospermum infection occurring within 2 weeks were successfully treated with voriconazole. Since both patients were infected with an uncommon pathogen, a search for a common nosocomial source was performed. As environmental cultures yielded no S. apiospermum, and random amplified polymorphic DNA (RAPD) fingerprinting showed that the patients' strains were genotypically unrelated, we considered a common nosocomial source of S. apiospermum to be unlikely.

Aged↗
PubMed2000

The prevalence and incidence of hepatitis C virus infections among dialysis patients in the Netherlands: a nationwide prospective study.

A nationwide prospective survey on hepatitis C virus (HCV) infections among dialysis patients in The Netherlands was performed. Patients were recruited from 34 dialysis centers and were tested for antibodies and HCV RNA in 1995 and 1997. Seronegative serum samples were analyzed by reverse-transcriptase polymerase chain reaction in pools. HCV-RNA-positive serum samples were genotyped and were partly sequenced. In the first and second rounds, 67 (2.9%) of 2281 and 76 (3.4%) of 2286 patients were HCV positive, respectively. Of 960 patients with paired serum samples, 35 were HCV positive in both rounds, and 9 HCV-positive cases were newly identified in the second round. The incidence of HCV infection was 0.5 per 100 dialysis years. Phylogenetic analysis revealed clustered sequences that indicated nosocomial transmission. Sixty percent of HCV infections, however, can be attributed to 4 interdependent risk factors (i.e., hemodialysis before 1992, kidney transplantation before 1994, and birth or dialysis in a foreign country). In conclusion, the prevalence of HCV infections in The Netherlands does not decline, and transmission within dialysis units continues. Adequate screening of HCV infections and strict enforcement of universal infection control practices are required.

Case-Control Studies↗
PubMed2000

Evaluation of clinical guidelines for the management of end-stage renal disease in europe: the EU BIOMED 1 study.

BACKGROUND: There are wide national and international variations in the management of patients with end-stage renal disease (ESRD). The aim of this study was to develop, harmonize, implement, and evaluate consensus-based clinical guidelines for the management of renal anaemia and renal bone disease in patients with ESRD, and for the prevention and management of cytomegalovirus disease in renal transplant recipients across six renal centres in Europe. METHODS: The trial was a prospective, multicentre, randomized balanced incomplete block design. Nephrologists from the six European renal units were randomized to develop and implement guidelines for two out of the three conditions and to act as a control for the third condition. Data were collected pre- (1 year) and post- (9 months) intervention on aspects of patient monitoring, management, and outcome. RESULTS: Eight hundred and twenty-nine dialysis patients from the six European dialysis centres were included in the study. Multivariate analysis (adjusting for case-mix and secular trends) showed a significant increase in the number of monitoring events in the guideline group compared with control group (6%, 95% CI, 1-11%). There was no concomitant increase in either appropriate management or the number of favourable patient outcomes. CONCLUSIONS: In the first European collaboration on renal guidelines, the introduction of the guidelines improved the monitoring of the patients, but did not improve patient management or outcome. This study suggests the potential for creating clinical guidelines with the aim of standardizing treatment protocols across international boundaries, and improving the quality of the medical care provided.

Adolescent↗
PubMed2000

Ankle edema formation during treatment with the calcium channel blockers lacidipine and amlodipine: a single-centre study.

All studies suggesting a lower incidence of edema on lacidipine than on amlodipine are based on subjective scoring. Therefore, we have compared edema formation on two dihydropyridine calcium channel blockers, using an accurate method for quantitative assessment of foot volume. In a randomized study, we treated 62 patients with essential hypertension for 12 weeks starting with either lacidipine 4 mg o.d. (n = 30) or amlodipine 5 mg o.d. (n = 32). At 6 weeks, the doses were increased to that maximally allowed (lacidipine 6 mg, n = 18; amlodipine 10 mg, n = 12) if trough diastolic blood pressure response was insufficient (>90 mmHg and decrease < 10 mmHg). Edema, scored visually, occurred more frequently (p = 0.02) on amlodipine (15/32) than on lacidipine (6/30); this was confirmed by an increase of foot volume above the 95% upper limit of normal variation in 15 patients on amlodipine and in only five patients on lacidipine (p = 0.01). In the whole group of patients, both the increases of foot volume and the decreases of blood pressure just failed to be significantly different between amlodipine and ]acidipine (foot volume, +3.3+/-1.0% on amlodipine and +1.2+/-0.5% on lacidipine, p = 0.08; mean arterial pressure, -11+/-1% on amlodipine and -8+/-1% on lacidipine, p = 0.052). In patients requiring dose increase, the increase of foot volume on amlodipine was more pronounced (p < 0.05), and the antihypertensive effect was larger (p < 0.05) than on lacidipine. In conclusion, our data show a higher incidence of edema on amlodipine than on lacidipine, which has to be explained at least partly by a comparably higher dose c.q. a larger antihypertensive effect of amlodipine. Other mechanisms might have contributed to these differences and need to be explored.

Adolescent↗
PubMed1999

Circulating concentrations of soluble interleukin 6 receptors gp80 and gp130 in chronic renal failure and effects of renal replacement therapy.

BACKGROUND: Circulating receptors modulate the biological effects of cytokines. Renal insufficiency is known to influence the concentrations of the soluble tumor necrosis factor (TNF) receptors p55 and p75. No data are available on the concentrations of the circulating interleukin 6 (IL-6) receptors gp80 and gp130 during chronic renal insufficiency. METHODS: We compared the serum concentrations of the IL-6 receptors gp80 and gp130 to those of the TNF receptors p55 and p75 in end-stage chronic renal failure, continuous ambulatory peritoneal dialysis, and hemodialysis (HD). RESULTS: In healthy controls the concentrations of gp80, gp130, p55, and p75 in serum were 82.1 +/- 24.3, 87.9 +/- 20.2, 1.1 +/- 0.2, and 1.7 +/- 0.3 ng/ml, respectively. These concentrations were increased to, respectively, 112.2 +/- 18.0, 186.0 +/- 37.7, 10.5 +/- 4.3, and 15.0 +/- 7.5 ng/ml in chronic renal failure, to 138.8 +/- 18.0, 181. 3 +/- 46.1, 25.5 +/- 5.2, and 19.1 +/- 3.4 ng/ml in continuous ambulatory peritoneal dialysis, and to 107.9 +/- 29.4, 146.6 +/- 30. 5, 22.9 +/- 6.3, and 16.8 +/- 6.0 ng/ ml in HD (before dialysis session). The concentrations after HD were higher for p75 only. CONCLUSIONS: The data show that the concentrations of the IL-6 receptors (gp80 and gp130) are elevated in chronic renal insufficiency. The increase is relatively low as compared with the elevation of the TNF receptors in this situation. HD does not result in a consistent change in serum concentrations of the various receptors.

Aging↗
PubMed1998

Comparing outcomes in renal replacement therapy: how should we correct for case mix?

The need to evaluate the effectiveness of clinical practice to justify expensive therapy in the face of financial constraints in all areas of health care delivery makes it necessary to identify groups of patients who are likely to benefit most from treatment. Various risk stratification methods have been used for analyzing survival probabilities for patients receiving renal replacement therapy. Complicated risk stratification methods produce large numbers of risk groups of small sizes, which makes comparison between individual centers difficult. We compared three simple methods of risk stratification, that divided patients into low-, medium-, and high-risk groups, in a cohort of 1,407 patients who commenced renal replacement therapy in five European countries during a 7-year period. Method 1 considered age (>55 years) and diabetes alone; method 2 used a higher age limit (>70 years) and comorbid illnesses, including those other than diabetes; and method 3 used only the number of comorbidities (none, 1, or > or =2) for stratification. Kaplan-Meier survival curves were constructed for comparison between risk groups and Cox's regression model used to assess strength of relationship with mortality. Although patient survival was significantly different between the low-, medium-, and high-risk groups using all three methods, Cox's regression analysis showed that method 2 provided the greatest discrimination between risk groups. In predicting mortality, method 2 (based on comorbidities and age) showed the highest sensitivity and specificity (84% and 80%, respectively) compared with method 1 (80% and 74%) and method 3 (64% and 82%). Validation of this approach in other populations in a prospective study is required before this method, which takes into account the influences of both age and comorbidity for risk stratification, can be used for comparing survival data and for presenting results of renal replacement therapy.

Adolescent↗
PubMed1998

Infection control of hepatitis C in Dutch dialysis centres.

BACKGROUND: In dialysis patients, blood transfusions and long-term dialysis are well-known risk factors for transmission of hepatitis C virus (HCV). Transmission of HCV by transfusions has become extremely rare since the introduction of antibody screening. However, nosocomial transmission of HCV within dialysis units still occurs. We performed a survey of current infection control measures against HCV in Dutch dialysis centres that had participated in a national HCV prevalence study. METHODS: All twenty-seven Dutch dialysis centres where HCV-positive patients had been identified (HCV prevalence 1-8%), participated. With the use of a questionnaire we evaluated screening procedures for resident patients and guest patients, routine hygienic measures in HCV-positive and -negative patients, and cleaning procedures of dialysis equipment. RESULTS: All centres except one screened new patients for HCV antibodies, but the frequency of periodic follow-up screening varied. Most centres requested HCV antibody screening of guest patients in advance, but in daily practice 55% of the centres dialysed guest patients even when HCV antibody status was not available. The majority of centres had not implemented special precautions for patients with unknown HCV antibody status. In most centres the use of protective glasses, masks and aprons depended on the HCV antibody status of the patients. Surprisingly, 85% of the centres allowed their nurses to operate dialysis machines with gloves possibly blood contaminated. All centres sterilized their machines at the end of the day, but only 77% sterilized their machines between all dialysis sessions. Traces of blood were removed with alcohol in 63% of the centres. CONCLUSION: Dutch dialysis centres have not yet implemented an optimal policy for prevention of HCV. Especially, operating dialysis machines with gloves might be a potential source for nosocomial transmission of HCV, not yet covered by the issued guidelines. Because dialysis patients probably have a prolonged serological window phase after a recent HCV infection, it does not suffice to implement a preventive strategy against nosocomial transmission based on the results of HCV antibody screening. Universal, rigorous implementation of adequate infection control measures irrespective of HCV antibody status should be the cornerstone for prevention of nosocomial transmission of HCV and other blood borne pathogens.

Ambulatory Care Facilities↗
PubMed1998

Renal and systemic effects of atenolol and tertatolol in renal transplant recipients on cyclosporine A.

BACKGROUND: Hypertension and nephrotoxicity are well-known side-effects of cyclosporine A (CsA). CsA-induced vasoconstriction of the afferent glomerular arteriole probably plays a role in at least the nephrotoxicity. Frequently renal transplant recipients on CsA have to be treated with antihypertensive drugs and for this purpose also beta-blockers are used. Tertatolol is a new beta-blocker with specific vasodilatory properties, and thus might be particularly useful in CsA-treated transplant recipients. METHODS: We studied the systemic and renal haemodynamic effects of atenolol and tertatolol in 12 hypertensive renal transplant recipients on cyclosporine A (CsA). In a cross-over way, all patients were treated with atenolol and tertatolol for 4 weeks each, separated by a wash-out period also of 4 weeks. At the end of each period, the mean arterial pressure (MAP), heart rate, glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured. RESULTS: The mean arterial pressure was lower (P < 0.05) during atenolol (124 +/- 2 mm Hg) and tertatolol (125 +/- 2 mm Hg) treatment compared with washout (132 +/- 4 mm Hg). Also the heart rate was lower (P < 0.01) during atenolol and tertatolol (54 +/- 3 and 55 +/- 2 beats/min respectively) than in the wash-out period (65 +/- 3 beats/min). GFR and RPF were not changed by either beta-blocker. CONCLUSION: In CsA treated renal transplant recipients both atenolol and tertatolol effectively reduced blood pressure. In these patients we found no evidence of a specific vasodilatory effect of tertatolol. Both beta-blockers had no negative influence on renal function. Hence, these cardioprotective agents are an attractive and safe choice for the treatment of hypertension in such patients.

Adrenergic beta-Antagonists↗
PubMed1996

Survival on renal replacement therapy in Europe: is there a 'centre effect'?

OBJECTIVE: Survival is the ultimate outcome measure in renal replacement therapy (RRT) and may be used to compare performance among centres. Such comparison, however, is meaningless if the influences of comorbidity, age and early deaths are not considered. We therefore studied survival rates on RRT in seven centres in Europe after taking into account the influence of age, early deaths, primary renal diagnoses, and comorbidity. DESIGN: A retrospective survival analysis was carried out on 1407 patients who commenced RRT in seven centres across five European countries during a 7-year period. Patients were stratified into low-, medium- and high-risk groups based mainly on comorbidity and to a lesser extent on age at commencement of RRT. Kaplan-Meier survival and Cox's proportional hazards model were used to compare survival. RESULTS: Before risk stratification overall 2-year survival across the seven centres ranged from 60.2 to 85.3% (69.3-89.9%) after excluding early deaths) masking a range of survivals of 27.4% for the high-risk group with the worst survival to 100% in the low-risk group with the best survival. After excluding early deaths 2-year survival in the low risk groups (n=622) was greater than 90% in all centres. Multivariate analysis showed that the mortality risk increased four fold from low- to medium- and a further 1.6-fold from medium- to high-risk group. However, despite this adjustment for comorbidity and age there still remained a significant difference in survival among some centres, i.e. a 'centre effect' which ranked the centres. CONCLUSION: Risk stratification diminishes the variance in survival between centres but a centre effect remains despite adjusting for age and comorbidity. Multicentre prospective studies are urgently required to identify the reasons for this apparent centre effect.

Adult↗
PubMed1996

Oedema formation with the vasodilators nifedipine and diazoxide: direct local effect or sodium retention?

OBJECTIVE: To determine whether the common side effect of ankle oedema with arteriolar vasodilators such as the calcium entry blocker (CEB) nifedipine and the potassium channel opener (PCO) diazoxide is the direct result of peripheral vasodilation or merely a consequence of renal sodium retention. DESIGN: In 12 healthy sitting volunteers we studied for 3 h the effects of 20 mg nifedipine, 150 mg diazoxide intravenously, 25 mg captopril and placebo on oedema formation and sodium excretion. CONCLUSIONS: Foot swelling was determined with a new accurate device (coefficient of variation 0.30%), which uses Archimedes principle to measure water displacement induced by immersion of the foot. Blood pressures were recorded with a Hawksley random-zero sphygmomanometer. RESULTS: All of the active drugs decreased diastolic blood pressure (captopril by 9 +/- 2%, nifedipine by 4 +/- 3% and diazoxide by 2 +/- 2%, compared with an increase of 5 +/- 2% with placebo). Foot volume increased acutely after administration of nifedipine (by 2.6 +/- 0.4%), whereas it remained stable with placebo and the other drugs. Administration of captopril and nifedipine induced increases of fractional sodium excretion (by 20 +/- 9% and 40 +/- 20%, respectively) in contrast to the decreases with placebo and diazoxide (by 13 +/- 11% and 24 +/- 10%, respectively). Only administration of nifedipine induced significant, albeit small, increases in haemoglobin and serum albumin levels. CONCLUSIONS: Administration of nifedipine increased foot volume and natriuresis simultaneously, thereby supporting the hypothesis that development of ankle oedema with CEB is a local phenomenon at the site of vasodilation. The absence of a similar increase in foot volume with diazoxide administration should be interpreted with caution because of the rather minor effect of this dose of diazoxide on blood pressure. However, it could be indicative of a different mechanism of oedema formation with PCO.

Adult↗
PubMed1994

Acute effects of nifedipine in renal transplant recipients treated with cyclosporine or azathioprine.

Cyclosporine (CsA) impairs renal function, probably by preglomerular vasoconstriction. Vasodilating substances may therefore be of benefit to ameliorate CsA-induced renal dysfunction. We studied the acute effects on blood pressure and renal function of the dihydropyridine calcium antagonist nifedipine (10 mg orally) in 20 CsA-treated renal transplant patients. In addition, we compared the effects of nifedipine when given immediately before and 4 weeks after elective conversion from CsA to azathioprine. Compared with placebo (n = 14), administration of nifedipine led to a significant decrease in blood pressure and a strong natriuretic and diuretic response. Despite the reduction in blood pressure, glomerular filtration rate improved from 60 +/- 20 (mean +/- SD) to 69 +/- 24 mL/min/1.73 m2 (P < 0.001) and renal plasma flow (RPF) increased from 260 +/- 87 to 338 +/- 120 mL/min/1.73 m2 (P < 0.001). The combination of a decreased blood pressure with an increased RPF was reflected in a sharp decrease in renal vascular resistance (0.34 +/- 0.18 units v 0.23 +/- 0.10 units; P < 0.001). The conversion from CsA to azathioprine by itself led to significant increases in glomerular filtration rate (62 +/- 15 mL/min/1.73 m2 v 76 +/- 18 mL/min/1.73 m2; P < 0.05) and RPF (280 +/- 86 mL/min/1.73 m2 v 334 +/- 66 mL/min/1.73 m2; P < 0.05). During treatment with azathioprine an effect of nifedipine on glomerular filtration rate and RPF was no longer observed, although the natriuretic effect was similar on both occasions. The decrease in renal vascular resistance was larger during treatment with CsA than during treatment with azathioprine (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Azathioprine↗
PubMed1994

Metoclopramide stimulates kaliuresis during felodipine without affecting its natriuresis.

Calcium entry blockers such as felodipine induce natriuresis without a parallel rise of potassium excretion. Previous studies with exogenous aldosterone and felodipine have suggested that the absence of kaliuresis might be explained by a felodipine-induced inhibition of aldosterone release. The natriuresis with calcium entry blockers could not be attributed to a similar mechanism but might be due to the stimulation of intrarenal natriuretic systems such as the dopaminergic system. We studied whether the aselective dopamine antagonist metoclopramide prevents the natriuresis with low and therapeutic felodipine doses and whether metoclopramide-induced aldosterone release promotes kaliuresis with felodipine. Twelve healthy male volunteers participated in a randomized, placebo-controlled, crossover study comparing felodipine infusion during metoclopramide with felodipine alone. Metoclopramide had no significant influence on the pronounced and dose-dependent increases of renal plasma flow and urinary sodium excretion with felodipine. Metoclopramide increased plasma aldosterone concentration from 0.17 +/- 0.03 to 0.60 +/- 0.14 nmol/L, and subsequent felodipine infusion clearly increased urinary potassium excretion by 23 +/- 6 and 35 +/- 8 mumol/min (low and therapeutic doses, respectively). In contrast, potassium excretion remained stable with felodipine alone (+5 +/- 4 and +7 +/- 5 mumol/min, respectively). In conclusion, the natriuretic action of calcium entry blockers cannot be blocked by the aselective dopamine antagonist metoclopramide. This natriuresis is accompanied by kaliuresis only in the presence of elevated endogenous aldosterone concentrations. The ability of calcium entry blockers to prevent a rise of plasma aldosterone thus seems essential for the prevention of urinary potassium losses.

Adult↗
PubMed1993

Angiotensin converting enzyme inhibition does not prevent the natriuretic effect of felodipine.

The mechanism of natriuresis with calcium entry blockers such as felodipine is largely unexplained. As these drugs prevent sodium retention following exogenous angiotensin II, the natriuretic effect of felodipine might be due to a similar interaction with endogenous angiotensin II. In such a case, angiotensin converting enzyme inhibition with ramipril should prevent natriuresis with felodipine. We tested this hypothesis in a randomized, double-blind, crossover study in 12 male volunteers by comparing intravenous felodipine after 1 week of oral ramipril with felodipine after placebo and with solvent after ramipril. Ramipril pretreatment reduced ACE activity to 11 +/- 1%, lowered the blood pressure, and increased renal blood flow. However, ramipril pretreatment did not prevent the pronounced increase in natriuresis and diuresis with felodipine. Fractional sodium excretion only tended to increase less during felodipine after ramipril than during felodipine after placebo (absolute changes of + 1.2 +/- 0.2 and + 1.7 +/- 0.2%, respectively; p = 0.07). Ramipril did not influence the felodipine-mediated blood pressure reduction and renal vasodilation. In conclusion, ACE inhibition has no significant effect on the natriuretic and hemodynamic effects of felodipine, suggesting that mechanisms other than interaction with endogenous angiotensin II are involved in these effects of calcium entry blockers.

Adult↗