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Biomedical subjects

H Mann

Publications and source records attributed to H Mann.

At least 37 records · Page 2Linked to original sources
PubMed2000

Sodium modeling.

The most serious side effects induced by hemodialysis therapy are caused by changes in sodium concentration and subsequent water shift between the intracellular and extracellular fluid compartment. Because of inadequate precision of proportioning, a certain sodium concentration and considerable error in the measurement of sodium concentration in dialysis fluid and plasma water, an error of up to 10 g in the diffusive exchange of sodium chloride remains in most dialysis sessions. Common side effects occur within this sodium balance error. Sodium modeling is a simplified mathematical method to describe quantitatively the fluid exchange in the body caused by changes in extracellular sodium concentration. It is based on fundamental physiologic properties of sodium and its permeability through the corresponding membranes. It also explains the different working mechanisms of sodium- and urea-related changes in osmolarity. Sodium modeling is a helpful tool for the illustration of the effects of changes in sodium concentration and ultrafiltration rate on sodium balance during one dialysis session. Sodium profiling is a method employed to avoid unwanted side effects of hemodialysis therapy by deliberately changing the sodium concentration in dialysis fluid during the course of a dialysis session. Clinical reports on practicing sodium profiling are unsatisfactory, involving only short trial periods in most cases. Most of the studies reported positive sodium balance with temporary decreases in intradialytic hypotension and less blood volume reduction, but with increases in thirst and body weight. To date, no validated studies with suitable control of sodium balance have been published that clearly demonstrate the long-term benefits of this mode of therapy compared with the use of constant dialysate sodium concentrations.

Humans↗
PubMed1999

Importance of sodium dodecyl sulfate pore-graduated polyacrylamide gel electrophoresis in the differential diagnostic of Balkan nephropathy.

Balkan nephropathy (BN) is an endemic disease, which leads to end-stage renal failure and artificial renal replacement therapy. Pathologically it is characterized by progressive interstitial nephritis in a large population of villages situated in the proximity of a bend of the Danube up to a distance of 100 km from the river in several parts of Bulgaria, Romania, and the former Yugoslavia. The urinary proteins of 19 patients with BN from the region of Vratza, Bulgaria were examined using ultrathin layer sodium dodecyl sulfate (SDS) pore-graduated polyacrylamide gel electrophoresis (PAGE) and silver staining. The documentation of urinary proteins pattern was performed using laser densitometry and consecutive electronic processing for the purpose of characterizing and quantifying protein excretion. Our results show that the proteinuria of BN is predominantly tubular, consisting of low molecular weight species (10-65 kilodaltons). The amount of tubular protein changes with the progression of the disease. SDS-polyacrylamide gel electrophoresis (PAGE) is a diagnostic method for early diagnosis of tubular failure in BN. Using our method of SDS-PAGE, tubular failure can be detected even at a total protein concentration below 0.1 g/L and when the serum creatinine concentration is normal. Additionally, our method of SDS-PAGE supports the differentiation of BN from glomerular disease.

Aged↗
PubMed1999

Pathological excretion patterns of urinary proteins in renal cell cancer patients exposed to trichloroethylene.

A study was carried out to investigate urinary protein excretion patterns by means of SDS-polyacrylamide-gel-electrophoresis (SDS-PAGE) in renal cell cancer patients who had previously been exposed to high levels of trichloroethylene. Thirty-eight out of 41 (93%) renal cell cancer patients investigated had former extensive trichloroethylene exposure, but only 23 out of 50 (46%) renal cell cancer patients without a history of occupational exposure to trichloroethylene revealed urinary protein patterns indicative of toxic effects on the tubular system. One hundred controls without histories of overt renal disease and not occupationally exposed to trichloroethylene were examined in the same way; only 11 (11%) of them displayed protein excretion patterns indicative of damage to the renal tubule. These results are supported by alpha 1-microglobulin excretion data. The following conclusions are drawn: (1) Substantially more cases of tubular damage are found amongst renal cell carcinoma patients having been exposed to substantial levels of trichloroethylene over many years as compared with renal cell carcinoma patients not exposed to trichloroethylene. (2) The results support the view that chronic tubular damage is a precondition for the nephrocarcinogenic effect of trichloroethylene. (3) The findings indicate that urine protein patterns, on the basis of the SDS-PAGE methodology, represent a 'biological effect parameter' for the medical surveillance of persons occupationally exposed to trichloroethylene.

Aged↗
PubMed1999

Dialysis and pregnancy--a case report and review of the literature.

We report on a patient with an eight-year history on maintenance hemodialysis treatment without residual renal function in whom pregnancy was successfully managed through to the 29th week. During this time, under carefully modified dialysis treatment, the nephrologic course, as well as materno-fetal flow relationships were unremarkable. Fetal development was appropriate for gestational age. However, pregnancy was complicated by polyhydramnios, which necessitated i.v. tocolysis. In the 28 + 6th week of gestation, cesarean section was performed because of an antibiotic-resistant fever of unclear origin which ceased within two days of delivery. Although the postnatal course of the adequately developed baby was complicated by the respiratory distress syndrome, normal development continued. We emphasize that the intensive interdisciplinary cooperation of nephrologists and obstetricians is imperative for the successful management of pregnancy under these conditions. In these pregnancies, the main fetal problems consist of premature labor because of polyhydramnios, preterm delivery, intrauterine growth retardation and stillbirth. The mother is threatened by the development of superimposed pre-eclampsia, left ventricular failure because of volume overload and progressive anemia. In order to maintain a well-balanced homeostasis, intensification of dialysis therapy by an increase in frequency and duration is the most important therapeutic approach. Accurate fetal monitoring including frequent examination of the feto-maternal circulation by Doppler sonography as well as attentive surveillance of the mother is required to recognize the above mentioned complications.

Adult↗
PubMed1998

Isolation and structural characterization of five oligosaccharide alpha1-phosphates and one sulfated glycopeptide from hemofiltrate.

Five oligosaccharide alpha1-phosphates and one sulfated glycopeptide have been isolated from the hemofiltrate of one patient with end-stage renal disease. Isolation of these compounds has been achieved using reverse osmosis, ion-exchange and size-exclusion chromatography and high performance liquid chromatography. The structures were predominantly elucidated by one- and two-dimensional 1H and 31P NMR spectroscopy. The chemical structures were determined to be: 1 NeuAc alpha2-3Gal alpha1-OPO3H2; 2 NeuAc alpha2-6Galbeta1-4GlcNAc alpha1-OPO3H2; 3 NeuAc alpha2-3Galbeta1-3GalNAc alpha1-OPO3H2; 4 NeuAc alpha2-3Galbeta1-3[NeuAc alpha2-6]GalNAc alpha1-OPO3H2 (proposed structure); 5 Fuc alpha1-2Galbeta1-4[Fuc alpha1-3]GlcNAc alpha1-OPO3H2; 6 HOSO3-4Fuc alpha1-6GlcNAcbeta1-NAsn. While 2 and 3 have been previously characterized as compounds of urine and hemofiltrate, the oligosaccharide alpha1-phosphates 1, 4, and 5 could be isolated--to our knowledge--for the first time from biological material. Compound 6 is the first glycopeptide reported to contain a 4-sulfated fucose residue.

Female↗
PubMed1998

Uteroplacental and fetoplacental blood flow in a patient with renal anemia.

We report on Doppler sonographic findings of a dialysis patient with renal anemia during otherwise uncomplicated pregnancy. Uteroplacental and fetoplacental flow relationships before, as well as after the dialysis treatments during the course of the pregnancy were in the normal range. The favorable flow condition in the utero- and fetoplacental circulation was associated with a low hematocrit. This in accordance with previous reports indicates a more favorable maternal and fetal outcome in association with a low hematocrit/hemoglobin concentration.

Adult↗
PubMed1997

Overexpression of superoxide dismutase and catalase in immortalized neural cells: toxic effects of hydrogen peroxide.

Hydrogen peroxide (H2O2) is a known toxicant which causes its damage via the production of hydroxyl radicals. It has been reported to cause both necrotic and apoptotic cell death. The present study was undertaken to evaluate the mode of H2O2-induced cell death and to assess if overexpression of catalase could protect against its toxicity. H2O2 causes cell death of immortalized CSM 14.1 neural cells in a dose-dependent manner. H2O2-induced death was associated with DNA laddering as shown by agarose gel electrophoresis. Stable overexpression of catalase by transfection of a vector containing human cDNA into these cells markedly attenuated H2O2-induced toxic effects. Transfection of a vector containing a SOD cDNA afforded no protection. These results indicate that H2O2 can lead to the activation of endonuclease enzyme that breaks DNA into oligosomes. These cells which overexpress catalase or SOD will help to determine the specific role of H2O2 or O2- in the deleterious effects of a number of toxins.

Catalase↗
PubMed1997

Differential toxic effects of methamphetamine (METH) and methylenedioxymethamphetamine (MDMA) in multidrug-resistant (mdr1a) knockout mice.

The toxic effects of methamphetamine (METH) (2.5, 5.0 and 10.0 mg/kg) and methylenedioxymethamphetamine (MDMA) (5.0, 10.0 and 20.0 mg/kg) on dopaminergic systems were assessed in the striatum and of the nucleus accumbens in mdr1a wild-type and knockout mice. METH caused significant dose-dependent decreases of dopamine (DA) and DA transporters (DAT) in the striatum and the nucleus accumbens (NAc) of both wild-type and knockout mice. The lowest doses of METH (2.5 mg/kg) caused only small changes in the wild-type, but marked. decreases in the mdr1a knockout mice. The two higher doses (5 mg/kg and 10 mg/kg) caused similar changes in both strains of mice. In contrast to METH, MDMA caused greater percentage decreases in DAT in the wild-type mice. For example, the lowest dose (5 mg/kg) caused significant decreases in DAT in the NAc of wild-type but not of mdr1a knockout mice. The highest dose (20 mg/kg) caused similar changes in both the strains. These results suggest that METH and MDMA interact differentially with P-glycoproteins. These observations document, for the first time, a role for these proteins in the entry of METH and MDMA into the brain via the blood-brain barrier, with P-glycoprotein possibly facilitating the entry of MDMA but interfering with that of METH into the brain.

Animals↗
PubMed1997

Ten-year follow-up results from the Goettingen Risk, Incidence and Prevalence Study (GRIPS). I. Risk factors for myocardial infarction in a cohort of 5790 men.

Besides the accepted major risk factors for myocardial infarction (MI), cholesterol, hypertension and smoking, several other variables such as lipoproteins, apolipoproteins, fibrinogen and family history of MI, have been considered, but their usefulness as predictors of MI is controversially discussed. The Göttingen Risk Incidence and Prevalence Study (GRIPS) aimed to evaluate the independent impact of the latter in comparison to the established risk factors. GRIPS is a prospective cohort study, which included 5790 men, aged 40-59.9 years, without cardiovascular disease at baseline. Multivariate logistic regression models for the estimation of the MI risk based on the 10-year follow-up data from 97.4% of the study participants established LDL cholesterol as the strongest predictor of MI. It was followed by family history of MI, Lp(a), age, smoking, systolic blood pressure, HDL cholesterol (inversely related) and plasma glucose (P < 0.001). Apolipoprotein B as well as the ratios total/HDL cholesterol, LDL/HDL cholesterol and Apo B/AI were less effective predictors than LDL cholesterol and did not contribute independently to the estimation of MI risk. Similarly apoprotein AI was a weaker predictor of MI risk then HDL cholesterol. GRIPS is the first prospective cohort study which clearly justifies the key role of LDL cholesterol in preventive strategies. However, the data also give strong support for the additional consideration of other risk factors for a valid estimation of the MI risk for an individual subject.

Blood Glucose↗
PubMed1996

Unaccustomed high-mileage vs intensity training-related changes in performance and serum amino acid levels.

To test the overtraining-related "imbalanced amino acid hypothesis" (19), the influence of an unaccustomed average 103 %.4 wk-1 increase in training mileage (ITV) on performance and on serum levels of individual amino acids (AAs) was examined in distance runners and controlled by an unaccustomed average 152%.4 wk-1 increase in tempo-pace and interval runs (ITI). Two mmol.l-1 lactate performance (2 LP) increased, 4 LP stagnated and total running distance (TD) decreased in the incremental test during ITV--which may indicate an ITV-dependent overtraining--in contrast to an ITI-related increase in 2 LP, 4 LP and TD. The summed serum AAs decreased in ITV (2744 +/- 534 vs 2933 +/- 663 umol.l-1; p < 0.05) in contrast to an ITI-related increase (3541 +/- 657 vs 3252 +/- 885 umol.l-1; p < 0.05) with an average 29% higher final summed AAs concentration during ITI (p < 0.05). During ITV 12 individual AAs decreased by 6-17%, 8 remained constant and 3 increased (Cys, Met, fTrp) by 6-19%, as opposed to an ITI-related increase in 16 AA by 6-55%. The observed ITV-related changes in serum AAs profile were smaller than after completing contests as a marathon, a 100 km-run or an ultra-triathlon. It may be concluded that the observed small changes in AAs profile or AAA/BCAA and AA/LNAA ratios only represent an epiphenomenon without recognizable influence on incremental test performance, since increases in fTrp/LNAA ratios (+28% in ITV vs +45% in ITI) were found to be related both to performance impairment (ITV) and improvement (ITI).

Adult↗
PubMed1995

Venous stenosis and occlusion in hemodialysis shunts: follow-up results of stent placement in 65 patients.

PURPOSE: To provide follow-up data on the use of self-expanding stents in hemodialysis fistulas to improve the technical success of balloon angioplasty. MATERIALS AND METHODS: Ninety-two self-expanding vascular stents were placed in 65 patients (29 men and 36 women 25-79 years of age; mean, 57.6 years) with failing hemodialysis fistulas or shunts. RESULTS: Stent placement was successful in all patients, but rethrombosis of the shunt occurred in six patients (10%) within 1 week. There were 96 episodes of reobstruction. In 87 cases, percutaneous or combined surgical and percutaneous repeat intervention was performed. The cumulative shunt function rate was 88% after 6 months, 86% after 1 year, and 77% after 2 years. CONCLUSION: Stent placement in hemodialysis fistulas helps treat lesions that cannot be adequately treated with percutaneous transluminal angioplasty (PTA) alone but has a follow-up patency rate similar to that of PTA. Standard central venous stents have a better patency rate than after PTA.

Adult↗
PubMed1995

[Quantification of aortic insufficiencies. Comparison between Doppler echocardiography and qualitative angiographic methods: apropos of a series of 60 consecutive patients].

Many doppler echocardiographic indices have been described for quantifying aortic regurgitation, posing the problem of the relative value of each. Therefore, the authors assessed the severity of aortic regurgitation in 60 consecutive patients (16 women and 44 men, mean age 56.7 years, range 7 to 84 years) by the four grades of Seller's classification with selective aortography. These results were compared with Doppler echocardiographic measurement of anterograde cardiac output (Qao), the pressure half time (PHT), diameter of the jet at its origin in M mode colour Doppler (DTM) and calculation of the regurgitant fraction (RF) by comparison of flow at the different cardiac orifices by a method previously described and validated in the author's laboratory with an interorifice correlation of 0.91 to 0.96 and confidence intervals at 95% of the order of 12%. The feasibility of doppler echocardiographic methods was good: 87.8% for PHT (58/66 patients), 90% for DTM (36/40 patients), 90.9% for Qao and RF (60/66 patients). The correlation with aortography was -0.65 (p < 0.01) for PHT; 0.91 (p < 0.01) for DTM, 0.80 (p < 0.01) for Qao and 0.92 (p < 0.005) for RF. However, there was a number of overlaps between Grades I and II and Grades III and IV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Removal of beta 2-microglobulin using grafted affinity adsorbents as therapeutic approach for the treatment of hemodialysis patients.

Patients undergoing long-term hemodialysis are increasingly faced with the problem of developing amyloidosis. This is particularly manifested in a deposition of amyloid in diverse tissues and joints. For the treatment and prevention of amyloidosis, novel affinity adsorbents, which were prepared on the basis of radiation grafted polyamide, have been developed to remove beta 2-microglobulin (beta 2-MG) which is the main constituent of the amyloid. Various affinity ligands, such as alkyl residues with different chain lengths, as well as collagen and gelatin were tested for removing beta 2-MG from human serum and hemofiltrates (HF). Collagen and gelatin carriers show the best adsorption performances. They remove > 95% and > 50% of the beta 2-MG from HF and serum, respectively. The results show that the present approach can be used as the basis for future development of beta 2-MG adsorbents as an additional means in the treatment of dialysis patients.

Adsorption↗