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Biomedical subjects

U Kuhlmann

Publications and source records attributed to U Kuhlmann.

At least 55 records · Page 3Linked to original sources
PubMed1994

Do different dialysis-membranes affect beta 2-microglobulin kinetics during chronic hemodialysis?

Hemodialysis is not an absolute prerequisite for the formation of beta 2-microglobulin amyloidosis, but it enhances the progression of this complication related to long-standing renal failure. Thus the clearance and turnover of beta 2-microglobulin seems to play a major role in this disease. In a prospective multicenter study the beta 2-microglobulin clearance was studied in 87 patients starting hemodialysis. Serum samples were taken prior to and after the first dialysis session and also before and after dialysis at 4, 6, 12, 16, 26 and 52 weeks. Patients were either treated by cuprophane or a polyacrylonitril membrane. At the start, the mean serum beta 2-microglobulin level was about 18 mg/L in patients treated with a cuprophane membrane, but the levels increased after hemodialysis and reached a plateau, which was always higher than in those treated with polyacrylonitril, which cleared beta 2-microglobulin from the serum. However, after 12 months the difference was no longer significant. Thus beta 2-microglobulin excretion during dialysis differs between the two membranes, but seems to lose its significance for the beta 2-microglobulin serum level in chronic hemodialysis treatment.

Acrylic Resins↗
PubMed1994

[Urea sensor for the continuous ammonium-selective enzymatic process control of the artificial kidney].

Presented is a flow-through method for continuous ammonium-selective enzymatic monitoring of the artificial kidney by means of a bioelectrochemical urea electrode. The urea is converted in an enzyme membrane by covalently bound urease and the ammonium ions are detected by a Nonactin-PVC-membrane. In addition to detailed data from the oxygen-independent solid-state contact sensor, curves are obtained on-line from the patient during the haemodialysis session. The advantages of the method are described in detail. Furthermore, the urea sensor can be used for measurements in heparinized blood.

Anti-Bacterial Agents↗
PubMed1993

Mass determination of 15-hydroxyprostaglandin dehydrogenase from human placenta and kinetic studies with (5Z, 8E, 10E, 12S)-12-hydroxy-5,8,10-heptadecatrienoic acid as substrate.

NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase catalyzes the first step in the metabolism of prostaglandins which is usually associated with physiological inactivation. A highly purified homogenous enzyme preparation from human placenta was used to determine the molecular mass and lack of quaternary structure of the enzyme. Furthermore we have examined enzyme kinetics of the purified enzyme with (5Z,8E,10E,12S)-12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) an equimolar coproduct of thromboxane biosynthesis. Using gel electrophoresis and gel filtration on FPLC, we could estimate a molecular mass of 28 +/- 1 kDa, indicating that the enzyme consists of one single protein chain. The exact molecular mass of the monomer was calculated by matrix-assisted laser desorption/ionization mass spectrometry to 28740 +/- 30 Da. (5Z,8E,10E)-12-oxo-5,8,10-heptadecatrienoic acid (oxo-HT) could be identified as the only product obtained from the enzymatic reaction with HHT. Quantification of this metabolite was achieved by gas chromatography/tandem mass spectrometry. The calculated enzyme kinetic constants for the formation of the metabolic product [Km (HHT) = 9.68 microM, Vi = 12.78 mU/micrograms] were in agreement with those determined for NADH formation (Km = 7.65 microM, Vi = 11.79 mU/micrograms). This demonstrates that HHT shows high affinity to the enzyme which is comparable to prostaglandin E2 (PGE2). As the product oxo-HT is a potent inhibitor of platelet aggregation, dehydrogenation of HHT might represent a biological activation step.

Chromatography, Gel↗
PubMed1993

Incidence and significance of pneumoperitoneum in continuous ambulatory peritoneal dialysis.

In a retrospective study we reviewed upright chest x-ray films of 101 continuous ambulatory peritoneal dialysis (CAPD) patients to determine the incidence and significance of free subdiaphragmal air. A pneumoperitoneum (PP) was diagnosed if a minimal shadow of free air was detected under the diaphragm. The amount of free air was determined by measuring the height and width of the subdiaphragmal air shadow. Of all CAPD patients, 33.6% (34 of 101) had at least one occurrence of PP. Thirteen of these 34 patients (38.2%) were diagnosed within 30 days after catheter implantation, 10 patients (29.5%) acquired a PP during an episode of peritonitis, and in 11 patients (32.4%) no additional risk factor could be determined. Patients radiographed within 30 days after catheter implantation showed a statistically significant higher incidence of PP compared with the same patients radiographed later (22% v 10%; P < 0.05). The incidence of PP in CAPD patients suffering from peritonitis (33%) was significantly higher than in patients without peritonitis (10%; P < 0.001). The amount of free air did not differ statistically significantly between the investigated groups. Only two patients with PP and peritonitis had surgically confirmed visceral perforation. Therefore, the main reason for PP seemed to be handling faults during CAPD bag exchange. There was no correlation between the organisms causing peritonitis and PP or the CAPD connector system and PP. In conclusion, a PP occurs in approximately one third of all CAPD patients and a visceral perforation cannot be diagnosed by the occurrence and amount of free subdiaphragmal air.

Adolescent↗
PubMed1993

Epidermal Langerhans cells in uremic patients on hemodialysis or continuous ambulatory peritoneal dialysis.

Skin biopsies of 33 uremic patients-13 patients on continuous ambulatory peritoneal dialysis (CAPD), 12 on hemodialysis (HD), 8 patients with end-stage renal disease (ESRD) before initiation of dialysis treatment-and 10 healthy volunteers were investigated to determine the number of Langerhans cells (LC) by light microscopy after staining for S-100 protein. The epidermal LC count was significantly lower in patients on CAPD (mean: 62.9 LC/mm2; p = 0.027) and patients on HD (mean: 30.4 LC/mm2; p = 0.0015) compared to controls (mean: 110.1 LC/mm2) and uremic patients before initiation of dialysis treatment (mean: 122.6 LC/mm2). The difference between LC counts of CAPD and HD patients did not reach statistical significance (p = 0.057). There was no relation between LC count and age (p = 0.057) or epidermal width (p = 0.26). No statistically significant correlation could be demonstrated between duration of dialysis and LC count (r = -0.33, p = 0.10). LC counts of CAPD patients with diabetes mellitus (n = 7) were not significantly different from those of nondiabetics (n = 6; p = 0.77). LC counts seem to be normal in uremic patients before dialysis treatment. The reduction in LC density in the skin of dialysis patients may contribute to immunodeficiency of uremic patients on regular dialysis treatment.

Adult↗
PubMed1993

Survival of 138 surgically placed straight double-cuff Tenckhoff catheters in patients on continuous ambulatory peritoneal dialysis.

OBJECTIVE: To determine the natural history of a surgically placed Tenckhoff catheter in patients on continuous ambulatory peritoneal dialysis (CAPD). DESIGN: Prospective 7-year study analyzing catheter survival of all catheters using the Kaplan-Meier life table methodology. SETTING: Teaching hospital, department of nephrology. PATIENTS: One hundred and fifteen unselected patients beginning CAPD. INTERVENTIONS: Removal of the catheter required for the following complications: exit-site or tunnel infections or relapsing peritonitis, outflow obstruction, pericatheter leak, and development of hernias. MAIN OUTCOME MEASURES: Period between insertion and removal of the catheter. RESULTS: The cumulative survival of all catheters after 1, 2, and 3 years of CAPD was 87%, 69% and 65%. Catheter survival of the first versus the second catheter after 1 year was significantly longer (p = 0.03). The difference was not significant in relation to diabetes, age, and sex. Infectious complications caused 61% (n = 19) of all 31 catheter failures, mainly due to tunnel infections caused by Staphylococcus aureus (n = 12). "Mechanical" complications accounted for 49% (n = 12) of catheter failures. Eight of 12 mechanical complications were outflow failures. Seven patients had to be transferred to hemodialysis. CONCLUSIONS: The straight Tenckhoff catheter is a reliable peritoneal access device for CAPD in an unselected patient population.

Catheters, Indwelling↗
PubMed1992

Extracorporeal elimination of carbamazepine by haemoperfusion.

The clearance of the haemoperfusion cartridge H 200 C Tekin was determined in vitro for blood dissolved carbamazepine to test the efficiency of haemoperfusion treatment. In the first hour of in vitro haemoperfusion test of pig blood (concentration of carbamazepine 1084 mg/l) a clearance of 190 ml/min was obtained, which declined slightly to 150 ml/min after 4 hours. In a second test the elimination of carbamazepine from albumin solution was proven to be more than 1000 mg of carbamazepine after a four hour perfusion period using teflon coated charcoal. These results are in accordance with the clinical course of a 30 years old male patient who presented with severe hypoxaemia due to acute intoxication by 6 g carbamazepine. The carbamazepine blood level was 33.7 mg/l. Charcoal haemoperfusion was started immediately. A dramatic improvement of clinical symptoms was already observed during haemoperfusion. The carbamazepine serum level was 18.6 mg/l after 4 hours of haemoperfusion.

Adult↗
PubMed1992

Continuous ionography (CIG) in haemodialysis by ion-selective carrier membrane electrodes (ISCME) with solid cement contact for flow-through measurement.

Ion balance is of particular interest for patients maintained on RDT because of the importance of controlling ion movement and ion removal during haemodialysis. Continuous ionography (CIG) was therefore tested for electrolyte monitoring in extracorporeal haemodialysis in vitro and in vivo. The accuracy and stability of the electrodes were examined and various concentrations of potassium in blood, ultrafiltrate and dialysate were evaluated. Ion selective carrier membrane electrodes (ISCME) appeared to be suitable for continuous and simultaneous measurement of ions in blood and dialysis fluid. CIG monitoring of ion movement and ion removal could be the basis for adjusting and computer-managing ion elimination during extracorporeal haemodialysis.

Electrodes↗
PubMed1991

[Acute kidney failure caused by hantavirus infection].

A 37-year-old man suddenly fell ill with high fever (up to 39.6 degrees C), headache and lumbar pain. There was marked thrombocytopenia (minimal level of 48,000/microliters), moderate anaemia and a slow rise in serum lipase concentration to maximally 1352 U/l. Marked sinus bradycardia (to as low as 34 beats/min) occurred in the further course of the disease, as well as upper abdominal pain (endoscopically diagnosed as antral gastritis), subileus and splenomegaly. Two haemodialysis treatments were needed because of acute renal failure. An IgG antibody titre of 1:512 and an IgM titre of 1:80 against hantavirus antigen confirmed that this virus was responsible for the haemorrhagic fever with renal syndrome. This infection, transmitted by wild rodents and frequently observed in Asian countries, has a rising incidence in Central Europe. It should be included in the differential diagnosis of acute renal failure of uncertain cause.

Acute Disease↗
PubMed1991

[Therapy-refractory primary intestinal lymphangiectasis].

A 20-year-old man with severe physical weakness (from which he soon recovered spontaneously) was found to have hypoproteinaemia and lymphocytopenia (768/microliters). Ten years later, after having been free of symptoms in the meantime, oedema, ascites and abdominal pain occurred, associated with loss of physical capacity. Enteric loss of protein (alpha 1-antitrypsin clearance increased about thirtyfold) with a total serum protein concentration of only 3.7 g/dl, as well as histological evidence of lymphangiectasia of the small and large intestines provided the diagnosis of primary intestinal lymphangiectasia. In the course of the disease cholelithiasis and (after treatment with tranexamic acid) thrombosis of the axillary vein occurred. No treatment has been of any avail and the patient has been unable to work for three years.

Adult↗
PubMed1991

[Continuous ambulatory peritoneal dialysis. Patient and method survival rate, peritonitis incidence and dialysis efficacy over 10 years].

From 1979 to 1989, continuous ambulatory peritoneal dialysis (CAPD) was undertaken for terminal renal failure in 104 patients (56 women and 48 men; average age 54 +/- 15.3 years at the onset of dialysis), for a total observation period of 175 patients years. Survival rate for patients and methods and dialysis effectiveness were analysed retrospectively, the incidence of peritonitis prospectively, 40 patients were aged 60 years and over. Diabetic nephropathy was the most common cause of terminal renal failure (44%). Cumulative patient survival rate was 80% in the first year of treatment; 57% of patients were still alive after two years. The cause of death in 45 of the 54 patients who had died was unrelated to CAPD, cardiac disease and cerebrovascular accident being the most frequent causes (n = 26). During the first treatment year 47% of patients contracted bacterial peritonitis, 59% during the first two years. In 9% of patients CAPD had to be discontinued within the first two treatment years because of CAPD-related complications. There was no case of sclerosing peritonitis or of ultrafiltration loss forcing CAPD termination. These data indicate that there is no plausible explanation from a medical viewpoint for the highly restrictive use of CAPD in the Federal Republic of Germany.

Combined Modality Therapy↗
PubMed1991

In vivo effect of 1,25-dihydroxyvitamin D3 on phagocyte function in hemodialysis patients.

1,25-dihydroxyvitamin D3 [1,25(OH)2D3] has been shown to modulate the immune function of monocytes and macrophages. Patients with end-stage renal disease (ESRD) on chronic hemodialysis treatment usually present a deficiency of this active form of vitamin D3. The aim of this study was to investigate the effect of 1,25(OH)2D3 replacement therapy on phagocytosis, bactericidal capacity, and oxidative metabolism of peripheral blood polymorphonuclear leukocytes (PMNL) and monocytes (MN) in chronic hemodialysis patients. Phagocyte function tests were performed before and after four weeks of an oral replacement therapy with 0.5 micrograms/day of 1,25(OH)2D3 (Rocaltrol). The superoxide (O2-) generation of monocytes, measured by cytochrome c reduction and lucigenin-enhanced chemiluminescence (CL) from patients receiving hemodialysis treatment was significantly diminished compared to healthy controls. After the replacement therapy with 1,25(OH)2D3 the O2- production showed a significant improvement, resulting in an increased cytochrome c reduction and lucigenin-CL response. The bactericidal capacity of MN was also impaired and exhibited a significant enhancement of their killing activity after the administration of 1,25(OH)2D3. On the other hand, the luminol-enhanced CL, which reflects the myeloperoxidase-dependent oxidative metabolism, and the phagocytic ability of MN was not affected by the hormone. The function of polymorphonuclear leukocytes (PMNL) from hemodialysis patients showed no impairment in the state of 1,25(OH)2D3 deficiency and the replacement of the hormone did not enhance their function. These results suggest that the deficiency of 1,25(OH)2D3 in patients with ESRD on chronic hemodialysis treatment may be responsible for an impaired monocyte function, which could be improved by an in vivo replacement of the hormone.

Adult↗
PubMed1991

Pharmacokinetics, bioavailability, metabolism and acute and chronic antihypertensive effects of nitrendipine in patients with chronic renal failure and moderate to severe hypertension.

1. The pharmacokinetics, bioavailability, metabolism and antihypertensive effects of nitrendipine have been studied in 12 patients with impaired renal function and moderate to severe hypertension. The drug was administered simultaneously by the i.v. [13C4] and oral (commercial tablet 20 mg) routes. 2. No differences in the pharmacokinetic parameters were observed between the two routes of administration. The systemic clearance after i.v. administration in patients with renal impairment (18.2 +/- 6.1 ml min-1 kg-1) was similar to that observed in healthy volunteers. Despite complete absorption of drug from the tablet the bioavailability of the parent compound was 21.2 +/- 12.5%. Cumulative urinary excretion of nitrendipine metabolites was correlated with the creatinine clearance (r = 0.946). 3. Significant reductions in mean arterial blood pressure (mean: 23.6%) at the end of the nitrendipine infusion and after oral administration of 20 mg (mean: 17.5%) were observed. The blood pressure lowering effect of nitrendipine could be correlated within individuals with serum nitrendipine concentrations using a log linear model. 4. Following 4 weeks of therapy an average dose of 77 mg nitrendipine day-1 was required to achieve a systolic blood pressure below 160 mm Hg or a diastolic blood pressure below 90 mm Hg. The reduction in blood pressure during multiple dosing was related to the nitrendipine steady-state concentration. There was a significant relationship between the nitrendipine bioavailability and the dose required for sufficient blood pressure control. 5. No accumulation of nitrendipine caused by impaired renal function was observed during multiple dosing. Thus, no reduction of the nitrendipine dose in patients with renal impairment is necessary.

Adult↗
PubMed1991

[Ion-selective electro-analyser with tubular solid contact flow-through sensors for continuous bioelectrochemically controlled hemodialysis of K+, Na+, Ca2+, Cl- and pH].

An ion-selective electroanalyzer for bio-electrochemically controlled hemodialysis will be described. The bedside analysers are solid-contact flow-through electrodes based on tubular carrier-PVC-membranes for potassium, sodium, calcium and chloride. This multi-measurement system with series-connected biosensors in modular construction is provided with a chemosensor for pH measurements. Besides the technical aspects of the apparatus, the quantitative electrode characteristics and the fundamental basis for the application of ion activities in clinical analytic measurement will be described.

Acid-Base Equilibrium↗