Biomedical subjects

B Schmidt

Publications and source records attributed to B Schmidt.

At least 361 records · Page 20Linked to original sources

PubMed1991

Thioredoxin elicits a new dihydrolipoamide dehydrogenase activity by interaction with the electron-transferring flavoprotein in Clostridium litoralis and Eubacterium acidaminophilum.

The glycine-utilizing bacterium Clostridium litoralis contained two enzyme systems for oxidizing dihydrolipoamide. The first one was found to be a genuine dihydrolipoamide dehydrogenase, present only in low amounts. This enzyme had the typical dimeric structure with a subunit molecular mass of about 53 kDa; however, it reacted with both NADP (Km 0.11 mM) and NAD (Km 0.5 mM). The reduction of pyridine nucleotides by dihydrolipoamide was the strongly preferred reaction. A second dihydrolipoamide-oxidizing enzyme system consisted of the interaction of two proteins, the previously described NADP(H)-dependent electron-transferring flavoprotein (D. Dietrichs, M. Meyer, B. Schmidt, and J. R. Andreesen, J. Bacteriol. 172:2088-2095, 1990) and a thioredoxin. This enzyme system was responsible for most of the dihydrolipoamide dehydrogenase activity in cell extracts. The thioredoxin did not bind to DEAE, was heat stable, and had a molecular mass of about 15 kDa. N-terminal amino acid analysis of the first 38 amino acid residues resulted in 38% homology to Escherichia coli thioredoxin and about 76% homology to a corresponding protein isolated from the physiologically close related Eubacterium acidaminophilum. The protein of the latter organism had a molecular mass of about 14 kDa and stimulated the low dihydrolipoamide dehydrogenase activity of the corresponding flavoprotein. By this interaction with NADPH-dependent flavoproteins, a new assay system for thioredoxin was established. A function of thioredoxin in glycine metabolism of some anaerobic bacteria is proposed.

Amino Acid Sequence↗

PubMed1991

Measurement of backfiltration rates during hemodialysis with highly permeable membranes.

A method for determining local transmembrane fluid movement in a commercial hemodialyzer at low dialysate flow rates by measuring changes along the dialyzer length in the local concentration of a marker macromolecule added to the dialysis solution has been developed. The method was evaluated in vitro at zero net ultrafiltration using dialyzers containing polysulfone (n = 4) and cuprophane (n = 3) membranes. The local concentration of the marker macromolecule along the dialyzer length was higher than the input dialysate concentration only during experiments with dialyzers containing polysulfone membranes. These observations provide direct empirical evidence that fluid movement in the dialysate to blood direction, i.e., backfiltration, occurs during hemodialysis with this highly permeable membrane. Net rates of backfiltration for the dialyzer containing polysulfone membrane were also calculated from changes in the local concentration of the marker macromolecule and mass balance considerations. The calculated backfiltration rates increased with increasing blood flow rate and trended upward with increasing dialysate flow rate. The described methodology provides a novel approach for the further characterization of fluid and solute transport during hemodialysis with highly permeable membranes.

Hemofiltration↗

PubMed1991

Monocyte phenotype and interleukin-1 production in patients undergoing haemodialysis.

The expression of MHC class II (HLA-DR) and complement receptor (CR1) surface molecules on CD 14+ monocytes were compared with the production of the monokine interleukin-1 beta (IL-1 beta) in patients with endstage renal disease undergoing maintenance haemodialysis (HD) with hollow fibre dialyzers containing cellulose (CE, n = 8) and polysulfone (PS, n = 7) membranes. Monocyte staining was performed in blood samples obtained at the beginning and after 3 h of HD. Analysis of surface marker expression was done by immunofluorescence staining and flow cytometry analysis. Specific fluorescence intensity for both CR1 and class II (HLA-DR) antigens was increased in patients treated with CE membranes at the beginning of a dialysis treatment when compared to healthy control values. Interestingly, after 3 h on dialysis a further increase was noted for CR1 complement receptor expression whereas the increased HLA-DR expression was no longer detectable. In contrast, specific fluorescence intensity for both antigens was not significantly different from controls, either before or after dialysis, in patients treated with PS. The capacity of peripheral blood mononuclear cells to produce IL-1 beta spontaneously in vitro in the two patient groups was found to parallel results on phenotypic expression of surface molecules. The present study demonstrates that functional signs of monocyte activation, as evidenced by an augmented IL-1 beta production, in some patients on long-term HD correlate with an increased expression of two functionally important monocyte surface marker molecules.

Adult↗

PubMed1991

Effect of conditioned media of acute myeloid leukemia blast cells on complement synthesis by cultured human cells of monocyte and hepatocyte origin.

The effect of conditioned media of 3-day cultures of blast cells from peripheral blood of 5 patients with acute myeloid leukemia (CM-AML) was studied on the synthesis of C2, factor B (Bf) and C1 esterase inhibitor (C1-INH) by human monocyte-macrophage cultures and HepG2 hepatoma cell line. The level of C2 in the culture supernatants was measured by immune hemolysis, those of Bf and C1-INH by ELISA. CM-AML was added to the monocyte cultures on day 3 and replaced by culture fluid on day 6. Compared to the control cultures, CM-AML significantly increased C2 and Bf levels and slightly decreased C1-INH levels in the culture fluids on day 6. On day 9, Bf synthesis enhancement still could be observed but C2 and C1-INH levels did not significantly differ from those of the control. CM-AML significantly increased the synthesis of factor B by the HepG2 cells too. A strong correlation was found between the results of the Bf protein and RNA determinations, which means that the supernatants of AML blasts affect the gene expression of factor B at a pretranslational level. The selective complement synthesis modifying effect of CM-AML was not due to interferons (IFN) because neither IFN-alpha nor IFN-gamma could be detected in these conditioned media. The present findings indicate that the hypercomplementemia observed in AML patients can be due to unknown factor(s) produced by leukemic blast cells.

Blood Cells↗

PubMed1991

[Congenital muscular dystrophy: histochemical study of the skeletal muscle in 17 patients].

A thorough histological description of 17 patients with congenital muscular dystrophy (CMD) is presented. The biopsies were performed in the left superficial deltoid muscle and processed with histochemical techniques. All samples showed connective tissue proliferation, changes in the internal architecture, necrosis, increase of adipose tissue, macrophagia, fiber regeneration and segmentation, central nuclei, and type I fiber predominance. The histological hallmarks of this entity are the marked endomysial connective tissue proliferation that frames one fiber from the other, and the important changes in the fiber's internal architecture. Those two abnormalities are extremely helpful to differentiate, on histological grounds, CMD from limb girdle muscular dystrophy and Duchenne/Becker muscular dystrophy. CMD presents a particular natural course and should be individualized apart from other muscular dystrophies.

Diagnosis, Differential↗

PubMed1991

[Congenital muscular dystrophy: clinical study of 17 patients].

We concur with the idea that congenital muscular dystrophy (CMD) is a distinct clinical entity, and report 17 patients (2 negroes and 15 whites; 12 M and 5 F; median age 6 years, range 1 to 24 years) with genetic, clinical, laboratorial, electrophysiological and histochemical studies. All our cases have an inheritance compatible with an autosomal recessive pattern. A decrease in fetal movements was reported by 57% of the mothers, generalized hypotonia at birth was present in 82%, limb girdle and neck weakness, absent or decreased deep tendon reflexes, and limb contractures were present in all. Severe muscular wasting was found in 41%. Calf pseudo-hypertrophy was observed in one patient. A patient was severely mentally retarded and another was borderline. During a 30-month follow-up, the muscle weakness of the majority remained essentially unchanged but the degree of motor activity deteriorated and was proportional to the worsening of the limb contractures. Serum CK levels were normal or increased to a maximum of 8 times. The electromyogram was myopathic in 74%, neurogenic in 13% and normal in 13%. CT scans showed a symmetrical white matter hypodensity in the hemispheres in 8 cases. All but 5 patients were operated upon to release the limb contractures and all were submitted to physical therapy. The contractures recurred in 4 patients submitted to surgery and were probably related to the cessation of physical therapy.

Adolescent↗

PubMed1991

[Mitochondrial myopathy: report of 12 cases with histochemical study of the skeletal muscle].

Twelve patients with histologically defined mitochondrial myopathy are described. There were 9 males and 3 females. The age of onset ranged from birth to 35 years with a median of 14 years. The most common clinical picture was that of ophthalmoplegia, ptosis and muscle weakness found in 10 patients. One presented with exercise intolerance due to muscular aches and pains, and the other besides his muscular weakness had mental retardation and an aggressive behavior. The clinical presentation and differential diagnosis of these patients are discussed.

Adolescent↗

PubMed1991

[Follow-up of HIV infected patients with reduced pattern ERG].

We have recently reported a reduction of pattern electroretinogram (p-ERG) in patients with HIV infection. Amplitudes were reduced in HIV-infected patients with microangiopathy, but also in some cases with normal fundus. These findings suggested the existence of diffuse defects in ganglionic cell activity in HIV-infected patients. We have now started a prospective follow-up study in order to pursue the development of (a) p-ERG amplitudes and (b) funduscopic changes and visual acuity in these patients. In patients with normal fundus or microangiopathy who did not develop cytomegalovirus (CMV) retinitis, no significant tendency for the p-ERG amplitudes to fall could be demonstrated during the observation period of 1-16 (mean: 7) months. With the appearance of retinitis, the p-ERG amplitude decayed. In some cases, a pathologic p-ERG was recorded before retinitis appeared: 3 of 12 patients with p-ERG amplitudes in the pathological range later developed CMV retinitis and only 1 of 21 patients with normal p-ERG later developed retinitis. In some patients with AIDS or related disorders, p-ERG may be a useful additional diagnostic tool.

Adult↗

PubMed1991

[Management of varus knee arthrosis by high tibial osteotomy].

Authors made a follow-up of 69 varsus knee arthrosis treated with high tibial osteotomy. Beside the general results the effect of the severeness of the arthrosis before the correction and that of the gain of the axial correction on the result were also investigated. 56 (81 per cent) of the reexamined patient reported excellent or good results. The ratio of the successful operations was even higher in cases in which the femorotibial axis was corrected to physiological valgus (95 per cent). The best prognosis of the osteotomy is in the early stage of arthrosis (Ahlbäck 0-II). In cases of the more advanced process the ratio of the unsuccessful cases increases. In consequence it is stated that the best results can be expected after osteotomies performed in the early stage and leading to the physiological femorotibial valgus position.

Arthritis, Rheumatoid↗

PubMed1991

[The use of CO2 laser in bone surgery].

Authors examined during the trial of a CO2 laser of type TUNGSRAM TLS-61 the possibility of its use in the orthopaedic surgery. The output necessary to cut the skin and bony tissue, the speed of cutting and the extension of tissue necrosis were determined in experiments in vitro and in vivo. According to their observation the fusion of the bone cut with CO2 laser takes the same time as after the traditional osteotomy, however in the first three weeks the callus formation falls behind. The possibility of a curved cutting and of the coagulation haemostasis may ensure a fine prospect to this method.

Animals↗

PubMed1991

[Bone substitution with semisynthetic and natural apatite].

Authors demonstrate, based on animal experiment first in the literature of this country both the synthetic and the natural (coral) apatite as a bone substituting material. Complete and partial bone defects in 24 animals of the experience were filled with the materials examined. The speed of healing after the transplantation of the two implants, the mechanical characteristics of the healing bone (fracture solidity) are evaluated using both materials and in both types of the defect. It is stated that evaluable difference could not be observed from the viewpoint of the duration of healing between the two materials whereas considering the fracture solidity the coral substitution proved to be significantly better. The differences between the groups considering the complications (suppuration, pseudoarthrosis) are also assessed.

Animals↗

PubMed1991

Human recombinant macrophage colony-stimulating factor (M-CSF) increases Cl-esterase inhibitor (Cl-INH) synthesis by human monocytes.

The ability of macrophage colony-stimulating factor (M-CSF) to influence production of complement proteins by cultured human monocytes was studied. Three-day-old cultures of human monocytes were treated with 250-1000 U/ml recombinant human M-CSF (Cetus Corporation, Emeryville, CA). After 3 days the M-CSF containing medium was replaced by the same medium without M-CSF, and the cells were cultured for 3 more days. Samples taken at the removal of M-CSF and 3 days later were tested for the concentration of factor B and Cl-esterase inhibitor (Cl-INH) using ELISA methods, and C2 by using an immunohaemolytic assay. M-CSF induced a marked dose-dependent increase in the synthesis of Cl-INH, but did not significantly change Bf and C2 production. The findings suggest that M-CSF is able to influence selectively the complement protein-producing ability of cultured human monocytes.

Cells, Cultured↗

PubMed1990

[A basic psychodiagnostic program for internists].

The increasing frequency of disturbances of the health, in which psychic and/or social influential factors are significant, reflects also in the number of patients of the specialist of internal medicine who is working in the outpatient department, the hospital and in a subspeciality. This requires from the specialists of internal medicine, if he will satisfy the claims of his patients for a comprehensive diagnostics and effective therapy, from the very beginning and in all phases of the care the involvement of a basic psychodiagnostics. Hereby the problem in question is an enhanced internal establishment of the anamnesis under psychodiagnostic aspect, which serves for the clarification of psychic and/or social influences on signs and symptoms, the experience of the and the course of the disease. An orientating systematization and a way to the positive diagnostics of neuroses, psychosomatic diseases or disturbances and further functional syndromes in the field of internal medicine are presented which demand the graduated psychotherapeutic measure.

Humans↗

PubMed1990

Rat astrocytes express interferon-gamma immunoreactivity in normal optic nerve and after nerve transection.

Astrocytes are pivotal components of immune reactions in the CNS. We further support this notion by the localization of the lymphokine interferon-gamma (IFN-gamma), which plays an important role during immune responses, to astrocytes in rat optic nerve (ON). Astrocytes identified by glial fibrillary acidic protein immunoreactivity were IFN-gamma positive in normal and transected ON while oligodendrocytes did not express IFN-gamma immunoreactivity. These findings indicate that astrocytes can generate important signals which orchestrate immunoinflammatory responses in the brain.

Animals↗

PubMed1990

Phylogenetic conservation of arylsulfatases. cDNA cloning and expression of human arylsulfatase B.

A 2.2-kilobase cDNA clone for human arylsulfatase B (ASB) and several genomic clones were isolated and sequenced. The deduced amino acid sequence of 533 amino acids contains a 41-amino acid N-terminal signal peptide and a mature polypeptide of 492 amino acid residues. Overexpression of ASB in transfected baby hamster kidney (BHK) cells resulted in up to 68-fold higher ASB activity than in untransfected BHK cells. Pulse-chase labeling showed that ASB was synthesized and secreted as a 64-kDa precursor and processed to a 47-kDa mature form in BHK cells. The 47-kDa ASB form was located in dense lysosomes. Transport of ASB to the lysosomes was accomplished in a mannose 6-phosphate receptor-dependent manner. The ASB cDNA clone hybridizes to 4.8-, 2.5-, and 1.8-kilobase species of RNA from human fibroblasts. The same pattern was observed in RNA from fibroblasts of three Maroteaux-Lamy patients who were deficient in ASB activity, as well as in RNA from fibroblasts of three patients with multiple sulfatase deficiency, in which all known sulfatases were markedly diminished. Deduced amino acid sequences of human arylsulfatase A, human ASB, human steroid sulfatase, human glucosamine-6-sulfatase, and an arylsulfatase from sea urchin showed a substantial degree of similarity suggesting that they arose from a common ancestral gene and are members of an arylsulfatase gene family.

Amino Acid Sequence↗

PubMed1990

Thrombin generation in newborn plasma is critically dependent on the concentration of prothrombin.

The ability to generate thrombin is decreased and delayed in plasma from the healthy newborn infant compared to the adult. Only 30 to 50% of peak adult thrombin activity can be produced in neonatal plasma. To test whether this observation can be explained by the low neonatal levels of the contact or vitamin K dependent factors, we measured neonatal thrombin generation after raising the concentration of these factors to adult values. We also determined whether the addition of a variety of blood products to neonatal plasma improved thrombin generation. An amidolytic method was used to quantitate intrinsic (APTT) and extrinsic (PT) pathway thrombin generation in defibrinated pooled cord plasma from healthy term infants. Added individually, factors VII, IX, X or the contact factors (CF) failed to alter the rate or the total amount of thrombin generated in neonatal plasma. In contrast, the addition of prothrombin increased the total amount of thrombin generated to above adult values in both the APTT and the PT systems but did not alter the rate of thrombin generation. The rate of thrombin generation in cord plasma shortened after a combination of II, IX, X and CF was added to the APTT system or II, VII and X to the PT system. In both systems, the total amount of thrombin generated was linearly related to the initial prothrombin concentration. Each of fresh frozen plasma, cryoprecipitate, plasma from platelet concentrates, or factor IX concentrate (in amounts used therapeutically) caused an increase in the total amount of thrombin generated which was related to the increase in prothrombin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Factors↗

PubMed1990

Macrophages but not Schwann cells express Ia antigen in experimental autoimmune neuritis.

This study was designed to identify which cells express major histocompatibility complex class II (Ia) antigen in experimental autoimmune neuritis and may therefore be antigen presenters. Serial 1-micron-thick cryosections of ventral roots of animals with experimental autoimmune neuritis were labeled with Ox6 antibody against rat Ia, the ED1 antibody to identify monocytes/macrophages and an antiserum against S100, a marker for Schwann cells. Ia-positive cells were predominantly present before overt clinical signs and demyelination (day 12). At later stages when many axons were demyelinated, their number was markedly reduced. Few Ia-positive cells that had extending long processes, which over some distance were in immediate contact with several myelin sheaths, were scattered in normal-appearing nerve roots at these later time points. Most of the Ia-positive cells could be identified as ED1-positive lean monocytes/macrophages, but in contrast most phagocytic macrophages in advanced stages of myelin degradation no longer expressed Ia. Ia-positive structures were invariably negative for S100 at early and late stages of experimental autoimmune neuritis, indicating that Schwann cells did not express identifiable Ia antigen. These findings contrast with reports of expression of major histocompatibility complex class II antigens by Schwann cells in human neuropathies. Furthermore they do not support the notion that aberrant Ia expression by Schwann cells plays a major pathogenic role in experimental autoimmune disease of the peripheral nervous system.

Animals↗

PubMed1990

Isoproteins and an isoelectric focusing mutant of human apoprotein serum amyloid A.

On isoelectric focusing of human plasma and subsequent immunoblotting, using antii-human serum amyloid A (SAA) antibodies, a genetic variant of SAA was detected in a family of Turkish origin. All affected members of the family were apparent heterozygotes for the mutant protein, which underwent a charge shift of about one charge unit toward the anode. The variant is likely to be a mutant of the most prominent forms of SAA (SAA1 and SAA2, or SAA1 and SAA1 des Arg). The appearance of a genetic variant of two of the six reported SAA-isoforms in human plasma supports the concept of SAA proteins being products of different genes.

Antibody Formation↗