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Biomedical subjects

T Lenz

Publications and source records attributed to T Lenz.

At least 19 recordsLinked to original sources
PubMed2001

Angiotensin II infusion increases plasma erythropoietin levels via an angiotensin II type 1 receptor-dependent pathway.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEIs) have been shown to lower hematocrit and erythropoietin (EPO), but a direct link between angiotensin II (Ang II) and EPO in humans has not been shown. METHODS: Placebo or Ang II was infused for six hours in nine healthy male volunteers with and without blockade of the Ang II subtype 1 receptor (AT1R). EPO concentrations were measured 3, 6, 12, and 24 hours after the start of the infusion. RESULTS: Ang II raised the mean arterial pressure by about 20 mm Hg. Consistent with the known diurnal variation, EPO levels rose significantly (P < or = 0.02) during the day in all groups. During Ang II infusion, EPO levels rose to significantly higher levels after 6 and 12 hours compared with placebo [9.9 +/- 3.5 vs. 7.2 +/- 3.1 mU/mL (3 h, P = NS); 16.9 +/- 4.5 vs. 8.8 +/- 3.7 mU/mL (6 h, P = 0.01); 17.0 +/- 8.6 vs. 11.1 +/- 4.7 mU/mL (12 h, P = 0.01)] and returned to baseline after 24 hours (7.9 +/- 3.8 vs. 10.6 +/- 8.6 mU/mL, P = NS). With AT1R blockade, blood pressure remained normal during Ang II infusion, and EPO levels were never significantly different from placebo [6.8 +/- 4.8, 10.5 +/- 5.6, 13.1 +/- 9.0, and 12.4 +/- 10.1 mU/mL at 3, 6, 12, and 24 h after infusion, respectively, P = NS]. CONCLUSIONS: Ang II increases EPO levels in humans. This increase requires the participation of AT1R.

Adult↗
PubMed2000

Effect of angiotensin II infusion with and without angiotensin II type 1 receptor blockade on nitric oxide metabolism and endothelin in human beings: a placebo-controlled study in healthy volunteers.

BACKGROUND: Angiotensin II has been shown to induce the synthesis of endothelium-derived relaxing factor nitric oxide (NO) and endothelin in vitro. In human beings, to our knowledge, no data on NO release in response to angiotensin II and on the influence of angiotensin II type 1 receptor blockade have been published. METHODS: In a placebo-controlled study in nine healthy volunteers, angiotensin II was administered intravenously for 6 hours with and without pretreatment with valsartan, a specific angiotensin II type 1 receptor antagonist. NO (NO2 + NO3) and endothelin plasma concentrations, clearance values for inulin and paraaminohippuric acid and NO (NO2 + NO3) excretion in urine were determined. RESULTS: During angiotensin II infusion NO plasma concentrations remained unaltered compared with placebo after 3 hours: 6.66 +/- 5.49 versus 5.56 +/- 3.09 micromol/L (P = ns) but increased after 6 hours: 18.36 +/- 20.02 versus 7.13 +/- 3.87 micromol/L (P < .04). The same was noted after pretreatment with valsartan: 7.61 +/- 5.69 versus 5.56 +/- 3.09 micromol/L (P= ns) after 3 hours, and 21.70 +/- 11.51 versus 7.13 +/- 3.87 micromol/L (P = .02) after 6 hours. In urine fractional NO excretion decreased after angiotensin II infusion: 0.87 +/- 0.72 versus 0.95 +/- 0.71 (P = .5) during the first 3 hours, and 0.44 +/- 0.39 versus 0.78 +/- 0.43 (P = .01) during the following 3 hours. After valsartan pretreatment the decrease in fractional urinary NO excretion began earlier: 0.40 +/- 0.15 versus 0.95 +/- 0.71 (P = .04) during the first 3 hours, and 0.17 +/- 0.11 versus 0.78 +/- 0.43 (P = .01) during the following 3 hours. Endothelin plasma concentrations showed no difference after angiotensin II infusion with or without valsartan. CONCLUSIONS: Our observations demonstrate for the first time that angiotensin II increases NO plasma concentrations in human beings and that this response is not mediated by angiotensin II type 1 receptor. In spite of increased NO plasma levels, urinary NO excretion decreased. Endothelin plasma levels remained unchanged during angiotensin II infusion.

Adult↗
PubMed2000

Underestimation of 24-hour hypotensive efficacy of nifedipine GITS versus enalapril: ambulatory recording as an adjunct to clinical blood pressure measurement.

AIMS: Short-acting calcium entry blockers should be used primarily in slow-release form. Furthermore, studies of the antihypertensive efficacy of drugs can be negatively influenced by between 15% and 30% of the enrolled patients not being hypertensive according to ambulatory blood pressure (BP) measurement. Thus, a randomized double-blind multicenter parallel-group study was conducted to compare the effect of nifedipine GITS (gastrointestinal therapeutic system) with enalapril. METHODS AND RESULTS: After a 2-week placebo run-in period, 186 patients with a sitting diastolic BP > or = 95 mmHg were enrolled for an 8-week treatment period. They received 30-60 mg nifedipine GITS or 5-10 mg enalapril. Diastolic BP fell comparably from 99 to 87 mmHg (p < 0.01) in the nifedipine GITS group, and from 100 to 88 mmHg (p < 0.01) in the enalapril group. The increase in BP 2 h before waking, however, was suppressed significantly more by nifedipine. Furthermore, this study highlighted the existence of "whitecoat" hypertension in a number of patients, especially when clinical BP was used to identify hypertension. Of the patients who had been identified as hypertensive before randomization by standardized BP measurement, 53 (28.5%) were identified as non-hypertensives by 24-h BP monitoring. This led to an underestimation of the efficacy of the antihypertensive therapy. CONCLUSION: Nifedipine GITS as well as enalapril are comparably effective antihypertensive drugs.

Adult↗
PubMed2000

Blood pressure control in essential hypertension and impairment of renal function with age.

Hypertension has been recognized to be an important cause for the development of end-stage renal disease (ESRD). We assessed the quality of blood pressure control in 103 patients with essential hypertension and correlated renal function and age. Patients were stratified into three subgroups by their blood pressure level under current medication. Group 1 were hypertensive patients with normalized blood pressure (<140/90 mmHg, n = 25), group 2 patients with mild hypertension (140-159/90-99 mmHg, n = 43) and group 3 patients with moderate to severe hypertension (> 160/100 mmHg, n = 35). A negative correlation between age and creatinine clearance (Ccr) could be confirmed for patients of group 1 (correlation coefficient r1 = -0.56; p, < 0.01) and group 2 (r2 = -0.55; P2 < 0.001). Furthermore the regression coefficient (m) of decline in C(Cr) versus age was higher in group 2 patients (m2 = -1.83) than in group 1 (m1 = -1.30). In group 3 we found no correlation of renal function with age, indicating that age may not be the leading variable. Patients in group 1 were all within normal limits of age adjusted Ccr, but 12% in group 2 and 23% in group 3 had impaired C(Cr). Furthermore proteinuria was found to be 20% (group 1), 26% (group 2) and 31% (group 3). This analysis provides further evidence of the importance of blood pressure control in essential hypertension to preserve renal function.

Adaptation, Physiological↗
PubMed2000

Clinical evaluation of the efficacy of the Braun PrecisionSensor oscillometric wrist blood pressure monitor for use on adults versus auscultation as defined by ANSI/AAMI SP10-1992.

OBJECTIVE: To evaluate the overall performance of a new oscillometric wrist blood pressure monitor (Braun PrecisionSensor, Braun GmbH, Kronberg, Germany) as defined by the ANSI/AAMI SP10-1992 guidelines, and to analyze the data for the optimized selection of the algorithm that derives the blood pressure values from the oscillometric blood pressure curves. METHODS: The clinical trial was a multi-center, open, within-subject evaluation. Repeated sequential blood pressure measurements were taken on the left wrist using the Braun PrecisionSensor, and on the left upper arm using a T-tube stethoscope and a mercury sphygmomanometer as a standard auscultatory blood pressure measurement device. The reported results are based on a sample of 86 adult male and female subjects (57% female, 43% male). Three sets of measurements with each of both devices were evaluated for each individual. RESULTS: Close agreement was obtained between both observers in compliance with the ANSI/AAMI SP10-1992 guidelines. The mean values of the differences between the Braun PrecisionSensor and the mercury sphygmomanometer were 0.1mmHg for systolic and 1.9mmHg for diastolic blood pressure. The standard deviations were 7.1mmHg for systolic and 7.0mmHg for diastolic blood pressure. The use of an optimized algorithm improved the accuracy of the Braun PrecisionSensor, after which the standard deviations were 6.1mmHg for systolic and 6.3mmHg for diastolic blood pressure. CONCLUSIONS: The Braun PrecisionSensor satisfies the Association for the Advancement of Medical Instrumentation's efficacy and safety criteria for both systolic and diastolic blood pressures with both algorithms analyzed.

Adolescent↗
PubMed2000

Severity of HCV-induced liver damage alters glucose homeostasis in noncirrhotic patients with chronic HCV infection.

BACKGROUND/AIMS: To investigate the link between hepatitis C infection and glucose intolerance, we measured insulin sensitivity, glucose effectiveness and beta-cell secretion in noncirrhotic HCV-infected patients with normal glucose tolerance according to WHO criteria as assessed by oral glucose tolerance tests. METHODS: Glucose, insulin and C-peptide data from frequently sampled intravenous glucose tolerance tests were analyzed using the minimal modeling technique for glucose and C-peptide to determine insulin sensitivity, glucose effectiveness, first and second phase insulin secretion in noncirrhotic HCV-infected patients (n = 10) and in healthy control subjects (n = 10). Histological activity index (HAI) as well as the extent of fibrosis were evaluated by scoring liver biopsies. RESULTS: Insulin sensitivity (2.72 +/- 1.63 vs. 6.84 +/- 1. 20 10(-4) min(-1) per microU/ml, p < 0.01) and glucose effectiveness (2.29 +/- 0.45 vs. 2.89 +/- 0.39 10(-2) min(-1), p < 0.05) ere significantly lower in patients with HCV-induced liver disease. Insulin sensitivity was negatively related to serum alanine aminotransferase (r = -0.47, p < 0.05) and aspartate aminotransferase concentrations (r = -0.65, p < 0.05). Multiple linear regression analysis revealed a strong relation of insulin sensitivity with fibrosis score and HAI (r = -0.82, p < 0.02 for both). Second phase insulin secretion was significantly enhanced in HCV-infected patients (14.30 +/- 2.04 vs. 8.29 +/- 1.65 min(-1), p < 0.05). CONCLUSIONS: HCV-infected patients with normal glucose tolerance are insulin and glucose resistant. The impairment of glucose tolerance appears to be closely related with the severity of HCV-induced liver damage.

Adult↗
PubMed1999

[Spontaneous remission of Goodpasture syndrome in a 21-year-old patient].

HISTORY AND CLINICAL FINDINGS: A 21-year-old man was admitted twice within half-a-year because of fatigue and increasing dyspnoea. Both times the chest x-ray showed extensive pulmonary infiltrates. Clinical remission occurred within a few days of starting antibiotic treatment. INVESTIGATIONS: During the second admission an increased titre for antibodies against glomerular basement membrane was discovered (2560 U/ml); renal functions were normal, but there was haematuria. Renal biopsy revealed linear deposits of IgG along the glomerular basement membrane. DIAGNOSIS, TREATMENT AND COURSE: The pattern of findings indicated Goodpasture's syndrome. Immunosuppressive treatment and plasma separation did not have to be performed because spontaneous remission occurred within a few days. CONCLUSION: This case demonstrates that spontaneous remission may occur in Goodpasture's syndrome.

Adult↗
PubMed1999

Captopril test: time over?

OBJECTIVE: The role of non-invasive tests for the detection of renovascular hypertension is still a matter of controversy. The 'captopril test' is widely used; its clinical usefulness, however, remains questionable. The aim of the current study was therefore to report our own experience and to review the published data on the diagnostic significance of the test. PATIENTS AND METHODS: Data from 485 hypertensive patients who underwent a captopril test in consecutive order at our institution were analysed retrospectively. After a 30-min resting period in the supine position 50 mg of captopril was given orally. Blood was collected before and 90 min after dosage for the determination of plasma renin concentration (normal range 3.5-8.0 ng/ml/h). An increase by 100% or more of the baseline value was considered a positive response. Blood pressure was recorded at baseline and at 90 min. RESULTS: A positive response was present in 62 patients; further diagnostic work-up revealed significant renal artery stenosis in 11 of these patients. In the 423 patients with a negative response renal artery stenosis was found in three cases. With some limitations of retrospective analyses in mind, sensitivity and specificity of the test were calculated as 79% and 89%, respectively. No severe complication occurred during the test. CONCLUSION: Our data on the diagnostic indices and the safety of the captopril test are in good agreement with most published series. Altogether, available data suggest that the captopril test has a limited diagnostic accuracy as a screening test for the detection of renovascular hypertension. New radiologic non-invasive techniques with greater diagnostic value are therefore likely to challenge the clinical role of the test in the future.

Adolescent↗
PubMed1999

Interferon-alpha improves glucose tolerance in diabetic and non-diabetic patients with HCV-induced liver disease.

This pilot study was initiated to evaluate factors controlling glucose tolerance in patients with hepatitis C virus-induced liver disease before and after therapy with recombinant interferon-alpha (r-INF-alpha). Fifteen patients with histologically and serologically proven hepatitis C infection underwent oral and frequently sampled intravenous glucose tolerance tests (FSIGTT) before and after four months of therapy (6 x 106 U r-INF-alpha, subcutaneously, three times a week). Glucose, insulin and C-peptide data from FSIGTT were analysed using the minimal modeling technique to determine insulin sensitivity, glucose effectiveness and first and second phase insulin secretion. According to the WHO criteria 13 patients, had normal glucose tolerance; diabetes mellitus was diagnosed in 2 patients. In the morning following the last r-INF-alpha injection four months later, insulin sensitivity improved significantly in hepatitis C virus-infected patients with normal glucose tolerance (2.17 +/- 0.37 vs. 6.18 +/- 0.94 10(-4) min(-1) per microU/ml, p < 0.001) and with diabetes mellitus (0.86 to 2.61; 0.46 to 1.06 10(-4) min(-1) per microU/ml). This effect was independent of the extent of fibrosis, virus load before treatment and therapy response. First phase insulin secretion increased in non-diabetic (139.2 +/- 17.1 vs. 200.0 +/- 32.7, p < 0.05) and diabetic patients with HCV infection (55.24 to 118.5; 84.23 to 261.1). Moreover, free fatty acid concentrations in all HCV-infected patients were significantly reduced (0.48 +/- 0.01 vs 0.21 +/- 0.03 mmol/l, p < 0.01). Therapy with recombinant interferon-alpha is associated with an amelioration of glucose tolerance in non-diabetic and diabetic HCV-infected patients.

Adult↗
PubMed1999

Detection of acute phase response and infection. The role of procalcitonin and C-reactive protein.

OBJECTIVE: Established parameters, e.g. C-reactive protein (CRP), do not differentiate specifically enough between patients developing an infection and those exhibiting an acute phase response following cardiac surgery. The objective of this prospective study was to investigate if procalcitonin (PCT) is more helpful than CRP. METHODS: During a 1-year period, seven out of 563 patients (1.2%) developed systemic infections (group A) after cardiac operations with cardiopulmonary bypass (CPB), and additional eight patients (1.4%) had local wound infections requiring surgical therapy (group B). Blood samples for PCT and CRP measurements were taken preoperatively, at the onset of infection (d1), as well as on the third day (d3), fifth day (d5), and seventh day (d7) following diagnosis of infection. Forty-four randomly selected patients undergoing cardiac surgery with CPB without clinical signs of infection, additional intensive care unit (ICU) management or additional antibiotic treatment served as control (group C) to assess the PCT and CRP contribution to acute phase response. PCT and CRP levels were measured preoperatively, on the first (d1), third (d3) and fifth day (d5) after operation. RESULTS: At the onset of infection, PCT levels (median interquartile range 25%-75%) increased significantly in group A as compared to baseline values (10.86 (3.28-15.13) ng/ml vs. 0.12 (0.08-0.21) ng/ml), and decreased during treatment to still significantly elevated values on d5 (0.56 (0.51-0.85) ng/ml). CRP levels were significantly elevated on all days investigated with no trend towards normalisation (d1: 164.5 (137-223) mg/l) vs. 1.95 (1.1-2.8) mg/l preoperatively, d5: 181.1 (134-189.6) mg/l. In group B, no increase in PCT levels, but a significant increase of CRP from d1 (165.9 (96.6-181.6) mg/l) vs. 3.7 (2-4.3) mg/l preoperatively) until d5 98 (92.8-226.2) mg/l was detected. In group C, postoperative PCT levels increased slightly but significantly in the absence of infection on d1 (0.46 (0.26-0.77) ng/ml vs. 0.13 (0.08-0.19) ng/ml preoperatively), and d3 (0.37 (0.2-0.65) ng/ml and reached baseline on d5 (0.24 (0.11-0.51) ng/ml)). CRP levels were significantly elevated as compared to baseline on all postoperative days investigated (baseline: 1.75 (0.6-2.9) mg/l, d1: 97.5 (74.5-120) mg/l), d3: 114 (83.05-168.5) mg/l, d5: 51.4 (27.4-99.8) mg/l)). PCT showed a significant correlation to CRP in group A (r =0.48, p < 0.001), a weak correlation in group C (r=0.27, p=0.002) and no correlation in group B. Intergroup comparison revealed a significant difference for PCT between all groups (A>C>B) and significantly higher CRP levels in group A vs. C and in group B vs. C. Thus, the pattern high PCT/high CRP appears to indicate a systemic infection, while low PCT/high CRP indicates either acute phase response or local wound problems, but no systemic infection. The cost for PCT measurements was 5.6-fold higher as compared to CRP. CONCLUSION: Due to the significant differences in the degree of increase, PCT appears to be useful in discriminating between acute phase response following cardiac surgery with CPB or local problems and systemic infections, with additional CRP-measurement increasing the specificity.

Acute-Phase Reaction↗
PubMed1999

Hypertension is associated with hyperlipidemia, coronary heart disease and chronic graft failure in kidney transplant recipients.

BACKGROUND: Hypertension is a common concomitant condition in renal transplant recipients. There is accumulating evidence that this disorder is an important risk factor for chronic renal graft failure and other cardiovascular complications in these patients. SUBJECTS AND METHODS: The current retrospective study in 330 patients treated with cyclosporin or azathioprin covered 5 years and aimed to further characterize the interrelation between hypertension and renal graft failure. Furthermore, the association of hypertension with hyperlipidemia and the prevalence of coronary heart disease was evaluated. RESULTS: Altogether, before transplantation 182 patients were normotensive (no antihypertensive medication except diuretics) and 105 were hypertensive (blood pressure > 160/95 mmHg or patients requiring antihypertensive medication); for the remaining 43 patients no data were available. After transplantation the prevalence of hypertension in the cyclosporin group was 71, 76 and 70% after 1, 3 and 5 years, respectively. The respective numbers for the azathioprin group were 60, 59 and 58%. Hypertension was associated with graft dysfunction both in cyclosporin- and azathioprin-treated patients. Hyperlipidemia (cholesterol, triglycerides) was more severe in hypertensive than in normotensive patients. The prevalence for hypertension was higher in patients with coronary artery disease than in patients without the disease. CONCLUSION: The results further support the view that hypertension may be a risk factor for the development of chronic renal graft failure and coronary artery disease in this population. Furthermore, the association of hypertension with hyperlipidemia hints to an unfavorable accumulation of renal and cardiovascular risk factors in a large number of renal allograft recipients.

Azathioprine↗
PubMed1998

Contribution of angiotensin I converting enzyme gene polymorphism and angiotensinogen gene polymorphism to blood pressure regulation in essential hypertension.

The renin-angiotensin system (RAS) is involved in the pathogenesis of essential hypertension. In the present study we examined the genotype frequencies of the insertion/deletion polymorphisms of the ACE gene and the M235T polymorphism of the Angiotensinogen (Agt) gene in patients with essential hypertension in comparison with normotensive subjects. In hypertensive patients functional effects of blood pressure response to ACE inhibition were investigated. A total of 121 patients with essential hypertension (group 1) and 125 normotensive control subjects (group 2) were included in this study. All patients were genotyped by polymerase chain reactions (PCR) for the insertion/deletion (I/D) polymorphism of the ACE gene and the M235T polymorphism of the Agt gene. To analyze possible functional impacts on blood pressure regulation 50 mg of captopril was administered to hypertensive patients. No significant association of essential hypertension with polymorphisms of the Agt and ACE gene was found. The ACE serum levels in patients with the DD-genotype of the ACE I/D polymorphism were higher than in patients with the II-genotype (P < .01). In patients with the ID-genotype the ACE serum levels were in-between. A captopril test was performed in hypertensive patients. The patients were further divided into subgroups according to the diastolic and systolic blood pressure response. Group 1a consisted of patients with a diastolic blood pressure drop of > 5 mm Hg and group 1b with < or =5 mm Hg. Group 1c consisted of patients with a systolic blood pressure drop of > 10 mm Hg and group 1d with < or =10 mm Hg. Twice as many patients with the DD genotype of the ACE gene were found in group 1a compared to group 1b (chi(2) = 5.673; P = .017). No association of systolic blood pressure change to the investigated polymorphisms was found. Our results do not support the hypothesis that the investigated polymorphisms contribute to essential hypertension. Furthermore, no major impact of these polymorphisms on blood pressure response to captopril were detected. We conclude that the investigated genotypes have no influence on blood pressure level and homeostasis.

Adult↗
PubMed1998

Exhaustive exercise-induced tissue hypoxia does not change endothelin and big endothelin plasma levels in normal volunteers.

Chronic hypoxia has been shown to increase plasma endothelin levels. The current study was undertaken to examine the effect of exercise-induced tissue hypoxia on plasma levels of endothelin-1 (ET-1) and its precursor big endothelin-1 (Big-ET-1). After approval by the local ethical committee an incremental dynamic exercise test was performed in 12 physically trained volunteers (aged 20 to 40 years), using an electrically braked bicycle ergometer. The protocol included a step-wise increase of the workload until a heart rate of 130/min was reached, followed by a maintenance period of 25 min, and a further step-wise increase until exhaustion. Blood was drawn before, at several time points during, and 5 min after termination of the study for determination of ET-1, Big-ET-1, plasma renin activity (PRA), angiotensin converting enzyme (ACE), norepinephrine, epinephrine, and lactate. Lactate levels at baseline were 14.5 +/- 1.6 mg/dL (mean +/- SEM), which increased to 76.5 +/- 4.8 mg/dL at the time of exhaustion (P < .01). Baseline values for ET-1 and Big-ET-1 were 0.264 +/- 0.061 and 0.637 +/- 0.130 fmol/ml, respectively, which remained essentially unaltered throughout the exercise test. PRA was 1.46 +/- 0.45 ng/mL/h before exercise and increased to 3.55 +/- 0.96 ng/mL/h at exhaustion (P < .001). Norepinephrine and epinephrine were also increased at exhaustion. The study demonstrates that exhaustive physical exercise with acute development of pronounced tissue hypoxia--in contrast to chronic hypoxia--does not influence the release of ET-1 or Big-ET-1 or the conversion of the precursor to the active compound. Unlike endothelin, circulating renin and the catecholamines were markedly stimulated by this maneuver.

Adult↗
PubMed1998

Renal failure in giant cell vasculitis.

A 59-year-old white woman with temporal arteritis developed progressive renal failure. Renal biopsy results showed focal and segmental necrotizing glomerulonephritis; furthermore, giant cells were present in the destructed vessel walls. Immunosuppressive therapy did not prevent terminal renal failure. This case shows that renal involvement may be a feature of temporal arteritis.

Female↗
PubMed1998

Clonidine suppression test revisited.

BACKGROUND: The diagnosis of pheochromocytoma may be difficult because the clinical picture is variable. OBJECTIVE: The purpose of this paper is to report our experience and to review the published data on the diagnostic significance and risks of the clonidine suppression test in the diagnosis of pheochromocytoma. PATIENTS AND METHODS: 114 patients were evaluated for pheochromocytoma using the clonidine suppression test. RESULTS: The diagnosis was established in four patients. Overall accuracy of the test in our own series was 98% when the normal response to clonidine was defined as total plasma catecholamines of less than 500 ng/L, or less than 70% of the baseline value. No serious complication was noted. CONCLUSION: Our data and the published series demonstrate that the clonidine suppression test is accurate and safe in patients with suspected pheochromocytoma.

Adrenal Gland Neoplasms↗