PubMed Health⌕ Search

Biomedical subjects

H Hampl

Publications and source records attributed to H Hampl.

At least 55 records · Page 3Linked to original sources
PubMed1992

Essential branched-chain amino acids and alpha-ketoanalogues in haemodialysis patients.

Homeostasis of essential amino acids and their transamination derivatives (ketoacids) is disturbed in haemodialysis (HD) patients. In long-term HD patients a hypercatabolic state is often paired with severe anaemia. To understand metabolic regulation mechanisms we measured with an improved fluorescence-HPLC method plasma concentrations of valine (Val), isoleucine (Ile), and leucine (Leu) and their corresponding ketoacids ketoisovaleric acid (KIV), ketomethylvaleric acid (KMV), and ketoisocaproic acid (KIC). The values of 18 modestly anaemic HD patients (group A: Hb greater than 11 g/dl) and of 16 severely anaemic HD patients (group B: Hb less than 8 g/dl) were compared with 19 healthy control persons (100%; significance of patient values vs controls P less than 0.05) and with each other (significantly different at P less than 0.05). Both branched chain amino acids and ketoacids are diminished in HD patients. This disturbance of protein metabolism is intensified with severe anaemia. The decrease of transamination products KIV and KMV parallels that of their corresponding Val and Ile, whereas KIC is reduced out of proportion to Leu. Leu has anabolic function and KIC antiproteolytic effects. Decreased Leu and KIC indicate catabolism. Reduced transamination of Leu and KIC suggests an endogenous protective mechanism against catabolism independent of anaemia. These differences should be considered with supplementation therapy of branched-chain compounds in HD patients.

Adult↗
PubMed1992

Changed purine nucleotide concentrations and enzyme activities in erythrocytes of haemodialysis patients undergoing erythropoietin therapy.

Therapy of renal anaemia in haemodialysis patients with chronic renal failure by application of recombinant human erythropoietin leads to an increase of the haematocrit. Rejuvenation of the erythrocyte population results in a decrease of the median density (D50), an increase of cell age-dependent enzyme activities, such as aspartate aminotransferase, and elevated concentrations of purine nucleotides in the erythrocytes. After density gradient separation of erythrocyte populations into cell age-dependent fractions, the concentrations of adenosine-5'-triphosphate, guanosine-5'-triphosphate and guanosine-5'-diphosphate were be found to be elevated by 25-100% in all cell fractions from haemodialysis patients, compared with a healthy control group. Therapy of haemodialysis patients with recombinant human erythropoietin leads to further increase (65%) of ATP in the younger (low density) cells, but not in the older (high density) cells. The elevated concentrations of ATP and total adenine nucleotides during recombinant human erythropoietin therapy possibly result in improved deformability of erythrocytes. The data point to an enhancement of the proportion of younger erythrocytes, but not to an improvement of the reduced life span of erythrocytes of haemodialysis patients during therapy with recombinant human erythropoietin.

Adenosine Diphosphate↗
PubMed1991

Recurrent hyperparathyroidism after total parathyroidectomy and autotransplantation in patients with long-term hemodialysis.

From 1986 to 1990, we performed total parathyroidectomy with simultaneous autotransplantation (TPX with AT) of parathyroid tissue into the forearm in 13 patients on chronic maintenance hemodialysis with severe secondary hyperparathyroidism. The indications for surgery included persistent hypercalcemia, hyperphosphatemia, roentgenological signs of renal osteopathy, soft tissue calcifications and severe pruritus. The parathyroidectomy was performed by an experienced surgeon who removed all four parathyroid glands and transplanted 10 mm3 of parathyroid tissue into the brachioradialis muscle. After an average postoperative period of 33.5 months, 10 of 13 patients developed recurrent clinical and biochemical hyperparathyroidism requiring reoperation. Seven of these patients underwent removal of the autograft. In 5 patients, however, the success was minimal. Four of these patients had a second autograft resection, but only transient improvement resulted. Our recurrence rate after TPX with AT is very high. The histological aspect of the resected autograft is similar to tumor-like growth and this may account for the results. A therapeutic alternative to TPX with AT appears to be necessary.

Calcitriol↗
PubMed1990

Discrimination between HIV-1 and HIV-2-seropositive individuals using mouse monoclonal antibodies directed to HIV transmembrane proteins.

Mouse monoclonal antibodies directed against the transmembrane proteins of HIV-1 or HIV-2 provided site-directed, unambiguous discrimination between HIV-1 and HIV-2 antibody-positive sera, when employed in immunoassays as competitive probes against serum antibodies. These monoclonal antibodies mapped to epitopes outside of the well-characterized immunodominant regions (IDR) of the transmembrane proteins. The monoclonal competitive immunoassay was a superior method for discrimination compared with immunoprecipitation of metabolically radiolabeled HIV envelope glycoproteins, Western blot against viral envelope glycoproteins, or noncompetitive enzyme immunoassays employing HIV recombinant transmembrane proteins or synthetic IDR peptides as serological targets. The monoclonal competitive assay was not affected by antigenic cross reactivity or nonspecific reactivity exhibited by selected serum samples toward envelope proteins or peptides, respectively. Results of the monoclonal competitive immunoassay were supported by results of a peptide inhibition assay employing free IDR peptides in competition with IDR peptides on a solid support for binding of serum antibody. IDR peptide inhibition clearly demonstrated non-cross-reactive antigenic specificity of sera toward either the HIV-1 IDR or the HIV-2 IDR. The monoclonal competitive assay also identified samples containing antibody to both HIV-1 and HIV-2 transmembrane proteins. Analysis of these samples by IDR peptide inhibition indicated they contained two distinct, non-cross-reactive populations of antibodies, one directed to the HIV-1 IDR and the other directed to the HIV-2 IDR.

AIDS Serodiagnosis↗
PubMed1990

Comparison of heparin-sensitive attachment of pseudorabies virus (PRV) and herpes simplex virus type 1 and identification of heparin-binding PRV glycoproteins.

To determine whether heparan sulphate residues on the cellular surface could serve as an attachment receptor for pseudorabies virus (PRV), the effect of heparin on PRV in plaque reduction and adsorption tests was investigated. PRV was significantly less sensitive to heparin than was herpes simplex virus type 1 (HSV-1). At concentrations of 500 micrograms/ml heparin the number of plaques formed by PRV was reduced to 7% of the untreated control whereas the number of plaques formed by HSV-1 was reduced to below 0.1%. Adsorption of PRV to host cells was also less sensitive to heparin treatment than was adsorption of HSV-1. Experiments concerning the binding sites of PRV showed that heparin binds to the disulphide-linked glycoprotein complex gII (PRV gB), gIII (PRV gC) and probably gV.

Animals↗
PubMed1990

Processing of pseudorabies virus glycoprotein gII.

The glycoprotein complex gII of pseudorabies virus was isolated by immunoprecipitation with the monoclonal antibody M5, which was covalently linked to protein A-Sepharose. After sodium dodecyl sulfate-polyarylamide gel electrophoresis under reducing conditions and blotting onto poly(vinylidene difluoride) membrane, its subunits, gIIa, gIIb, and gIIc, were subjected to N-terminal sequencing. gIIa and gIIb start at position 59 and gIIc starts at position 503 according to the amino acid sequence deduced from the gene, indicating that there is one major protein (gIIa) which is cleaved into the two protein fragments gIIb and gIIc. Protein labeling with 14C-amino acids gave no indication that the three proteins (gIIa, gIIb, and gIIc) of the complex are present in equimolar ratios. It seems that gIIa is only a minor component of the complex, whereas gIIb and gIIc are contained in equimolar amounts.

Amino Acid Sequence↗
PubMed1990

Erythropoiesis and erythrocyte age distribution in hemodialysis patients undergoing erythropoietin therapy.

Renal anemia is caused in part by a reduced life span of red blood cells (RBCs) and by reduced erythropoietin biosynthesis in the damaged kidney. The RBC age can be determined by density gradient centrifugation and estimation of cell-age-dependent enzyme activities, as aspartate aminotransferase. The RBC age distribution influences the median density (D50) of RBCs and the blood rheology in coherence with the hematocrit. In our study, the median density was determined by Percoll density gradient centrifugation in 18 healthy subjects (D50 = 1.0674 +/- 0.0016 g/ml) and in 14 hemodialysis patients (D50 = 1.0674 +/- 0.0016 g/ml in the course of recombinant human erythropoietin (rhEPO) therapy. During the first 4 weeks of therapy, a strong rejuvenation of RBCs was observed whereby the D50 reached a minimum after 2 weeks (D50 = 1.0655 +/- 0.0022 g/ml; p less than 0.05 vs. value before therapy) and a steady state after 4 weeks (D50 = 1.0658 +/- 0.0013 g/ml; p less than 0.1 vs. value before therapy). In 5 of the patients with elevated plasma parathyroid hormone (i-PTH) concentrations greater than 10 pmol/l, a significantly (p less than 0.05) reduced amount of younger RBCs (D50 = 1.0675 +/- 0.0016 g/ml) was observed in the first 2 weeks of rhEPO therapy as compared to patients with i-PTH less than 10 pmol/l (D50 = 1.0677 +/- 0.0019 g/ml). Thus, erythropoiesis in the early phase of rhEPO therapy is strongly influenced by elevated plasma i-PTH concentrations. Therefore, a gradual increase in rhEPO doses is preferable before therapy at elevated doses with an uncontrolled increase in RBC amount.

Adult↗
PubMed1990

Red blood cell density distribution in uremic patients on acetate and bicarbonate hemodialysis.

Renal anemia is the result of reduced erythropoietin (EPO) biosynthesis in the diseased kidney and also in part the result of a reduced life span of red blood cells (RBCs). An increase in density and a decrease in enzyme equipment (aspartate aminotransferase; GOT) of RBCs reflect cell age. In the following study, the density distribution (median density D50; determined by Percoll density gradients) and GOT activities of RBCs were measured in patients on acetate (HDA; n = 15) and bicarbonate (HDB; n = 51) hemodialysis. Hemoglobin (Hb) concentrations were: in the HDB group, 9.1 +/- 3.4 g/dl; in the HDA group, 6.2 +/- 1.2 g/dl, and, in a control (C) group of healthy persons, 14.0 +/- 1.5 g/dl. 14 HDB patients with severe anemia received EPO therapy during 1 year. D50 were found as follows: group C, 1.0674 +/- 0.0016 g/ml; HDB, 1.0674 +/- 0.0015 g/ml, and HDA, 1.0660 +/- 0.0012 g/ml (HDA vs. group C: p less than 0.05; HDA vs. HDB: p less than 0.05. D50 were elevated in the subgroups of HDA and HDB patients with severe anemia (Hb less than 8 g/dl). During activated erythropoiesis by EPO therapy, D50 decreased from 1.06739 +/- 0.0015 to 1.0656 +/- 0.0014 g/ml. The GOT activities in RBCs demonstrated a rejuvenation of the RBC population in the HDB group (6.4 +/- 2.5 U/g Hb) and HDA group (5.9 +/- 3.1 U/g Hb) compared to group C (3.9 +/- 1.3 U/g Hb).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1989

Lysine-specific cleavage of beta 2-microglobulin in amyloid deposits associated with hemodialysis.

Amyloid fibrils isolated from bone and carpal synovia of seven patients on long-term hemodialysis were further characterized biochemically. In addition, renal amyloid stones of three dialyzed patients were examined. All deposits and stones were of beta 2-microglobulin-origin (AB-amyloid) by immunohistochemical and immunochemical evaluation. Amyloid fibril extracts were dissolved in 80% formic acid and separated by high performance liquid chromatography in 60% formic acid and 20% 2-propanol. Three major retarded fractions with molecular weights of approximately 24, 12 and 7 to 10 kD were recovered. N-terminal amino acid sequence analysis documented beta 2-microglobulin (beta 2m) as the principal polypeptide in all investigated cases. In addition to proteins with intact N-termini, one fragment commencing with isoleucine in position 7 was found in osseous or synovial amyloid. In renal amyloid stones, one additional fragment was found beginning with serine in position 20. Generally, these data point to proteolytic cleavage carboxyterminal to a lysine residue and establish that not only intact beta 2m but also at least one beta 2m fragment is present in beta 2m-derived amyloid deposits of patients with long-term hemodialysis. The fragmentation pattern is consistent with the action of lysine-specific protease(s) and underscores a potentially important role of limited proteolysis in the pathogenesis of AB-amyloid deposits.

Adult↗
PubMed1989

Changes in the concentrations of hydroxyproline, glycine and serine in the plasma of haemodialysis patients undergoing erythropoietin therapy.

The concentrations of proline, hydroxyproline, glycine and serine were determined in the plasma of 39 haemodialysis patients and 18 healthy subjects, using liquid chromatography with fluorescence detection. Plasma concentrations of the N-terminal immunoreactive parathyrin were also measured. In haemodialysis patients, the plasma concentrations of glycine (p less than 0.01), hydroxyproline (p less than 0.05) and proline (p less than 0.10) were significantly increased, whereas the serine concentrations (p less than 0.01) were decreased, compared with those of the healthy controls. Haemodialysis patients showed greatly elevated plasma N-terminal immunoreactive parathyrin values (greater than 30 pmol/l), which showed a significant correlation with the hydroxyproline values (r = 0.79). Fourteen haemodialysis patients received erythropoietin therapy. In these patients, changes in the concentrations of plasma amino acids were observed up to one year after the beginning of therapy. In the course of the erythropoietin therapy, the plasma concentrations of glycine (p less than 0.05) and hydroxyproline (p less than 0.10) of the haemodialysis patients decreased, whereas the concentration of serine increased (p less than 0.05) to approximately normal values. The results indicate that erythropoietin therapy leads to a normalization of amino acid metabolism.

Adult↗
PubMed1989

Correction of amino acid metabolism by recombinant human erythropoietin therapy in hemodialysis patients.

We assessed the effect of correction of anemia with recombinant human erythropoietin (rhEPO) on plasma amino acid levels in maintenance hemodialysis patients. The plasma amino acid pattern was estimated by high performance liquid chromatography in 18 healthy persons and 14 hemodialysis patients before and up to 12 weeks after rhEPO therapy. There was a correction of the plasma serine values (67 +/- 16 to 87 +/- 22; P less than 0.05) and a corresponding decrease in the serine precursors, glycine (317 +/- 113 to 228 +/- 56; P less than 0.05) and hydroxyproline (26 +/- 21 to 15 +/- 13; P less than 0.10). The low plasma branched-chain amino acids, valine (137 +/- 33 to 154 +/- 50; P less than 0.10) and leucine (72 +/- 22 to 80 +/- 27; P less than 0.20), also were corrected. The elevated values of ornithine (78 +/- 16 to 62 +/- 19; P less than 0.1) and arginine (94 +/- 14 to 72 +/- 14; P less than 0.1) fell. The diminished glutamine values (470 +/- 125 to 563 +/- 115; P less than 0.1) and the decreased tyrosine/phenylalanine ratio (0.78 +/- 0.17 to 0.98 +/- 0.21; P less than 0.05) rose. Thus, the administration of rhEPO not only affects erythropoiesis, but also corrects the plasma amino acid pattern towards normal.

Adult↗
PubMed1988

Non-responsiveness to hepatitis-B vaccination: revaccination and immunogenetic typing.

The variation in immune responses to standard inoculation of the hepatitis-B virus vaccine suggest that host factors influence response in ways that are not presently understood. We studied 25 low/nonresponding health care workers (anti-HBs titer less than 50 IU/l) after the third inoculation of an experimental hepatitis-B vaccine to determine their immune status (through lymphocyte phenotypes) and HLA type. After application of a fourth inoculation, the seroconverting subjects showed only low anti-HBs levels; three male subjects remained anti-HBs negative. Twelve months after the fourth inoculation only 9 of 25 subjects (36%) maintained anti-HBs titer greater than 10 IU/l. Almost all subjects had normal B-cell and CD-4 and CD-8 counts and ratios. Relative to other European populations HLA-A-10 (P less than 0.05), B-12 (P less than 0.025), CW-5 (P less than 0.05), DR-3 (P less than 0.025), and DR-5 (P less than 0.025) were increased, whereas DR-2 (P less than 0.05) was decreased. However, after correction of the P-values for the number of HLA antigens determined, these differences were no longer significant. Furthermore, these HLA types were not the same as those reported in other studies (except for DR-3). We suggest that larger sample sizes or even not yet available immunogenetic markers will be required to prove an "immunogenetic background" in low/nonresponders, if it exists.

Adolescent↗
PubMed1988

[Pulmonary complications in acquired immunodeficiency syndrome. Results of a prospective study].

Between 1983 and 1987, a stepwise diagnostic programme was undertaken prospectively in 37 of 100 HIV-positive patients with 40 bronchopulmonary infections. It consisted chiefly of flexible bronchoscopy combined with lavage, transbronchial biopsy and/or removal of bronchial brush cells. Taking into account all examinations performed in life and at autopsy, 25 of the 37 patients had Pneumocystis carinii pneumonia (67.5%), 13 had bacterial pneumonia, six of these were mycobacterial infections (atypical mycobacteria in four), eight had neoplasms (pulmonary Kaposi's sarcoma in five, squamous-cell carcinoma in two, and Hodgkin's disease in one), and four patients had cytomegalovirus infection. Total diagnostic success of bronchoscopy was 78%; related to Pneumocystis pneumonia it was 91%.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Release of a virus coded glycoprotein from herpes simplex virus type 1 infected cells.

HEp-2 cells, which were infected with HSV-1, excrete besides other proteins a soluble glycoprotein (Mr 125,000-130,000) related to the virus protein gC. The excretion of the glycoprotein and the production of extracellular virus particles is reduced to a similar extent when the cells were treated with monensin. Possible consequences of the excretion of soluble viral proteins to a modulation of the immune response are discussed.

Cells, Cultured↗