Search PubMed⌕ Search

Biomedical subjects

B Schmidt

Publications and source records attributed to B Schmidt.

At least 307 records · Page 17Linked to original sources
PubMed1993

Functional electrical stimulation (FES): muscle histochemical analysis.

Functional electrical stimulation (FES) has been used in Brazil since 1989 to obtain functional improvement in paraplegic patients' orthostasis and locomotion. The aim of this paper is to evaluate the histochemical changes observed in the quadriceps femoris muscle following the use of FES. We studied four patients with traumatic spinal cord lesions at T4-10 level, Frankel A, all within 12-24 months postlesion. They were all submitted to FES using the following criteria: square-wave, 20-30 Hz frequency, pulses of 0.003 seconds, time of stimulation 5 seconds, resting interval 10 seconds. The stimulation was applied during 90 consecutive days, 30 minutes each time, twice daily. The interval between the stimulations was 6 hours. Quadriceps muscle biopsies were performed before and after the use of FES. We used ATPase technique for the histochemical analysis, where three different dying patterns can be observed for the three types of muscular fibres (I, IIa and IIb). The two samples from each patient were analysed measuring the fibres' diameters and their index of atrophy, and counting the total number of each type of fibre in each sample. The mean total number of fibres in each sample was 256 +/- 12.3. The results showed that the sizes of the three types of fibres were not modified with the use of FES; the number of type IIa fibres increased in a significant fashion, after using of FES.

Adult↗
PubMed1993

Antibodies raised against synthetic peptides react with choline acetyltransferase in various immunoassays and in immunohistochemistry.

Antisera were raised in rabbits against five synthetic peptides. These peptides have been identified as potentially antigenic epitopes from the sequence of porcine choline acetyltransferase (ChAT) using primary and secondary structure analysis. All five antisera recognized immunoaffinity-purified antigen from porcine brain in an ELISA and on western blots. Four antisera recognized ChAT on dot blots, and another four antisera reacted with native and degraded enzyme in a sandwich ELISA using monoclonal antibodies as the capture antibody. One peptide antiserum was of similar avidity in this sandwich ELISA as a polyclonal antibody raised against immunoaffinity-purified ChAT. The same antiserum reacted with the enzyme from human placenta in an ELISA and on western and dot blots and recognized ChAT in rat, primate, and human neurons. Thus, a single peptide (amino acids 168-189) provides the means for easy, reliable, and reproducible generation of antibodies against ChAT suitable for replacing conventional polyclonal and monoclonal antibodies.

Animals↗
PubMed1993

Lipid apheresis by hemoperfusion: in vitro efficacy and ex vivo biocompatibility of a new low-density lipoprotein adsorber compatible with human whole blood.

To date, selective extracorporeal low-density lipoprotein (LDL) removal can only be performed from plasma; that is, a plasma-cell separation step using a centrifuge or a plasma membrane separator is necessary initially. This article characterizes a new polyacrylate-based LDL adsorber directly applicable to whole blood. In vitro single-pass hemoperfusion tests using pooled donor blood showed quantitative adsorption of atherogenic LDL-cholesterol (LDL-C) and complete recovery of protective high-density lipoprotein C. Fibrinogen, another independent risk factor of atherosclerosis, was also adsorbed to a lesser extent. Single-pass ex vivo biocompatibility using fresh donor blood on-line was excellent and resulted in minimal cell loss. Neither signs of hemolysis nor activation of monocytes (interleukin-1 production) were detected. Only slight activation of leukocytes (elastase release) and thrombocytes (platelet factor 4 secretion) as well as of coagulation (thrombin-antithrombin complex formation) and complement (C3a, C5a generation) was observed. Under the experimental conditions used, the optimal anticoagulation regimen was 0.5 IU heparin plus 0.375 mg citrate/ml blood. Priming the column with a buffer of pH 7.4 containing heparin, citrate, and Ca2+ is recommended. In conclusion, this new adsorber exhibited selective LDL-C adsorption in vitro combined with excellent ex vivo biocompatibility and thus holds great promise for a successful clinical application in a closed-loop system in patients.

Acrylic Resins↗
PubMed1993

Are 5-HT1A autoreceptors involved in the inhibitory effect of ipsapirone on cold-elicited thyrotropin secretion?

Administration of the serotonin (5-HT)1A receptor agonist ipsapirone has been shown to decrease cold-elicited thyrotropin (TSH) secretion. We have analyzed (1) the influence of 5-HT1A receptors and ipsapirone metabolism into 1-(2-pyrimidinyl)-piperazine (1-PP, an alpha 2-adrenoceptor antagonist) on the effect of ipsapirone on TSH release, and (2) the interaction between the corticosterone-releasing effect of ipsapirone and its inhibitory influence on TSH release. Pretreatment with proadifen (50 mg/kg, 5 h before ipsapirone), i.e. an inhibitor of ipsapirone metabolism into 1-PP, did not affect ipsapirone-induced inhibition of cold-elicited TSH secretion. Pretreatment (15 min before ipsapirone) with the 5-HT1/5-HT2 receptor antagonist metergoline 2 mg/kg) or with the 5-HT1A receptor blocker (-)-pindolol (5 mg/kg) increased baseline and cold-elicited TSH release but the inhibitory influence of ipsapirone on cold-elicited TSH release was alleviated by (-)-pindolol pretreatment only. Cold exposure increased corticosterone release, an effect which was insensitive to (-)-pindolol pretreatment. Lastly, pretreatment with the 5-HT synthesis inhibitor p-chlorophenylalanine prevented the immediate inhibitory effect of the selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) upon cold-induced TSH release, but it amplified the late release of TSH in cold-exposed 8-OH-DPAT-injected rats. These results suggest that presynaptic 5-HT1A receptors mediate ipsapirone-induced inhibition of cold-elicited TSH release, an effect which may be partially opposed by postsynaptic 5-HT1A receptor stimulation.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1993

Dengue. Muscle biopsy findings in 15 patients.

Dengue is known to produce a syndrome involving muscles, tendons and joints. The hallmark of this syndrome is severe myalgia but includes fever, cutaneous rash, and headache. The neuromuscular aspects of this infection are outlined only in isolated reports, and the muscle histopathological features during myalgia have not been described. In order to ascertain the actual neuromuscular involvement in dengue and better comprehend the histological nature of myalgia, we performed a clinical and neurological evaluation, a serum CPK level and a muscle biopsy (with histochemistry) in 15 patients (4 males), median age 23 years (range 14-47) with classic dengue fever, serologically confirmed, during the brazilian dengue epidemics from September 1986 to March 1987. All patients had a history of fever, headache and severe myalgia. Upon examination 4 had a cutaneous rash, 3 had fever, and 3 a small hepatomegaly. The neurological examination was unremarkable in all and included a manual muscle test. CPK was mildly elevated in only 3 patients. Muscle biopsy revealed a light to moderate perivascular mononuclear infiltrate in 12 patients and lipid accumulation in 11. Mild mitochondrial proliferation was seen in 3, few central nuclei in 3, rare foci of myonecrosis in 3, and 2 patients had type grouping. Dengue in our patients, produced myalgia but no detectable muscle weakness or other neuromuscular involvement. The main histopathological correlation with myalgia seems to be a perivascular mononuclear infiltrate and lipid accumulation.

Adolescent↗
PubMed1993

Mechanical properties of bone after grafting with coralline hydroxyapatite: an experimental study.

Based on animal experiments, mechanical properties of rabbit radii after grafting artificial gaps with a coralline hydroxyapatite (CH) material are discussed. Healing velocity of complete and partial gaps after the same kind of grafting is also analyzed. Based on the results obtained from 48 gaps of 24 animals it is stated that fused grafts in both types of gaps showed bending strength of the radii similar to that of normal bone. The incidence of nonunions and infections are also discussed. It is concluded that CH is suitable in the treatment of incomplete bone defects.

Animals↗
PubMed1993

Localization of interferon-gamma and Ia-antigen in T cell line-mediated experimental autoimmune encephalomyelitis.

This study reports the cellular localization of interferon-gamma (IFN-gamma) and MHC class II antigen (Ia) in the spinal cord of rats with experimental autoimmune encephalomyelitis induced by adoptive transfer of myelin basic protein-specific T cells. Numerous IFN-gamma-positive cells, stained with two different monoclonal antibodies against IFN-gamma, were present from days 3 to 7 after cell transfer. Their number was greatly reduced on day 10. A subpopulation of T cells was IFN-gamma positive. Moreover, a large number of ED1-positive macrophages contained IFN-gamma immunoreactivity. The transient presence of immune cells containing IFN-gamma immunoreactivity in experimental autoimmune encephalomyelitis suggests a pathogenic role of this cytokine in immune-mediated demyelination of the central nervous system.

Animals↗
PubMed1993

[Experimental study of postoperative scarring around the tendon sheath].

Authors have compared two kind of exposures of the flexor tendons. The results were assessed by measuring the flexion oft the given finger on pulling, by light and electron microscopic examination. It was found that in fingers where the tendon sheat was detached from the subcutis the scarring was greater and its effect, limiting the motion has its maximum on the fourth postoperative week. It is raised that the role of the tendon sheat in respect of the success of the flexor tendon reconstruction is mainly mechanic and most effective if its highly integrated connection with its surrounding is not disturbed.

Animals↗
PubMed1993

Prevention of blood loss in dialysers with DEAE-cellulose membranes does not require increased doses of heparin.

Binding of heparin to DEAE-cellulose membranes may reduce bioavailable heparin, thus increasing the amount of heparin needed for anticoagulation during dialysis. To test this hypothesis, blood loss and coagulation were evaluated during dialysis with DEAE-cellulose and polysulphone membranes. The heparin dose required to effect a given increase in the baseline recalcified activated clotting time (RACT) was determined using a pharmacokinetic model. Blood remaining in the dialyser post-dialysis (RBV) was measured by red cell lysis and haemoglobinometry. Plasma thrombin-antithrombin III complex (TAT) was used to assess activation of the coagulation system. RBV and changes in TAT were determined in two crossover studies. Firstly, DEAE-cellulose membranes were used at doses of heparin calculated to increase baseline RACT by 12.5% and 25%. Secondly, DEAE-cellulose and polysulphone membranes were compared at a heparin dose calculated to increase baseline RACT by 15%. RBV for DEAE-cellulose membranes was independent of the dose of heparin and did not differ from that found for polysulphone membranes. TAT concentrations increased during dialysis; however, there was no difference between the two membranes. These results show that DEAE-cellulose membranes do not require increased heparin to avoid dialyser-associated blood loss.

Adult↗
PubMed1993

[Results of osteotomies in the management of valgus gonarthrosis].

Authors report on the result of correction osteotomies in 31 cases of gonarthrosis, developed in consequence of valgus deformity. In 12 cases high tibial osteotomy, in 19 supracondylar femoral osteotomy were performed. The result was excellent in 15, good in 10 and poor in 6 patients. Decisive factors of the favourable result were partly the correction of the femorotibial valgus to around the physiological values, partly the horizontalization of the articular surface. In overcorrection the results deteriorate. The medial tilt of the tibial articular surface leads to the progression of the arthrosis. Supracondylar femoral osteotomy was found especially successful in the treatment of valgus gonarthrosis. High tibial osteotomy is suggested only in selective cases.

Adolescent↗
PubMed1993

Are single measurements of pseudocholinesterase and albumin markers for inflammatory activity or nutritional status in Crohn's disease?

Serum pseudocholinesterase (PCHE) activity and serum albumin concentration have been used as markers for inflammatory activity as well as malnutrition in Crohn's disease (CD) with controversial results. Therefore we investigated the valence of both proteins as markers of inflammation and/or malnutrition in 50 patients with active CD [Crohn's disease activity index (CDAI): median = 243; interquartile range = 191-288] and 70 patients with quiescent CD (CDAI: 62; 25-96). Thirty patients were malnourished, 18 with active [body weight: 84%; 79-88% IBW (ideal body weight)] and 12 with quiescent CD (87.5%; 81.5-88% IBW), and 90 patients were well nourished, 32 with active (96%; 93-112% IBW) and 58 with quiescent CD (104.5%; 96-116% IBW). Median values of PCHE activity and albumin concentration were within the normal range in both groups, in patients with active as well as quiescent CD. PCHE activity was decreased only in 24 patients (48%) with active, but also in 11 (15.7%) patients with quiescent disease. Albumin concentration was decreased in 12 patients (24%) with active and in one patient (1.4%) with quiescent disease. Comparing the two patient groups PCHE activity and albumin concentration were significantly lower in active than in quiescent CD [PCHE: 3.70 kU/l; 3.00-4.30 kU/l vs. 4.80 kU/l; 3.75-5.82 kU/l, p < 0.001; Albumin: 38.0 g/l; 35.1-39.9 g/l vs. 43.8 g/l; 40.8-46.3 g/l, p < 0.001]. Both proteins were significantly lower in malnourished than in well nourished patients, except albumin in patients with quiescent CD. Repeated measurements of PCHE and albumin in patients during and after active phases showed significant increases of both proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Isolation and identification of granule-associated proteins relevant for poly(3-hydroxyalkanoic acid) biosynthesis in Chromatium vinosum D.

Poly(3-hydroxybutyric acid) granules, which harbored only four major granule-associated proteins as revealed by SDS polyacrylamide gel electrophoresis, were isolated from crude cellular extracts of Chromatium vinosum D by centrifugation in a linear sucrose gradient. N-Terminal amino acid sequence determination identified two proteins of M(r) 41,000 and M(r) 40,000 as the phaECv and phaCCv translational products, respectively, of C. vinosum D. In a previous study it was shown that both proteins are required for the expression of poly(3-hydroxyalkanoic acid) synthase activity. The N-terminus of the third protein (M(r) 17,000) exhibited no homology to other proteins. Lysozyme, which was added during purification of the granules, exhibited a strong affinity to PHB granules and was identified as the fourth protein enriched with the granules.

Acyltransferases↗
PubMed1992

Cyclosporin synthetase is a 1.4 MDa multienzyme polypeptide. Re-evaluation of the molecular mass of various peptide synthetases.

The earlier determined molecular mass of 0.8 MDa for the multifunctional polypeptide, cyclosporin synthetase, was re-evaluated by SDS-PAGE and CsCl density gradient centrifugation. In SDS-PAGE, new molecular mass values as standards were available from sequencing data. In the CsCl density gradient extremely low protein concentrations, such as 10-50 nM could be analysed due to the fluorescence detection system of the analytical ultracentrifuge. Both methods yielded approximately the same value of about 1.4 MDa. Using this molecular mass of cyclosporin synthetase as a reference the molecular masses of various related enzymes could be re-evaluated in SDS-PAGE. The sedimentation coefficient of 26.3 S for cyclosporin synthetase indicates an oblate overall shape of the enzyme.

Cesium↗
PubMed1992

In vitro mutagenesis of potential N-glycosylation sites of arylsulfatase A. Effects on glycosylation, phosphorylation, and intracellular sorting.

The correct intracellular sorting of lysosomal enzymes such as arylsulfatase A depends on the presence of mannose 6-phosphate residues on high mannose type oligosaccharides. The arylsulfatase A cDNA contains three potential N-glycosylation sites, two of which are utilized. We have mutated one or two of the N-glycosylation sites and analyzed the glycosylation, phosphorylation, and intracellular sorting of the mutant arylsulfatase A polypeptides. The results show that each of the three glycosylation sites (I, II, and III) can be glycosylated, but glycosylation at sites I and II is mutually exclusive. In mutants with one oligosaccharide side chain at positions I, II, or III all side chains can acquire mannose 6-phosphate residues irrespective of their location. This demonstrates spatial flexibility of the phosphotransferase, which specifically recognizes lysosomal enzymes and initiates the addition of mannose 6-phosphate residues on oligosaccharide side chains. However, these mutants have different intracellular sorting efficiencies and seem to use different (mannose 6-phosphate receptor-dependent and -independent) sorting pathways.

Animals↗
PubMed1992

Phylogenetic conservation of cysteine proteinases. Cloning and expression of a cDNA coding for human cathepsin S.

A 1.8-kilobase full-length cDNA of human cathepsin S, a lysosomal cysteine proteinase, has been isolated. The single long open reading frame encodes a polypeptide of 331 amino acids consisting of a 15-amino acid NH2-terminal signal peptide, a propeptide of 99 amino acids, and a mature polypeptide of 217 amino acids. The deduced amino acid sequence contains only one potential N-glycosylation site located in the propeptide. The NH2-terminal amino acid sequence of the mature polypeptide was confirmed by sequencing cathepsin S purified from human spleen. The cDNA detects a 1.9-kilobase transcript in poly(A)+ RNA from human fibroblasts. Expression of human cathepsin S in transfected baby hamster kidney cells resulted in up to more than 300-fold cathepsin S activity as compared to untransfected controls. In the expressing baby hamster kidney cells, human cathepsin S is transported to the lysosomes via the mannose 6-phosphate receptor pathway as shown by density gradient centrifugation, immunofluorescence, and detection of the 37-kDa cathepsin S precursor in the medium in the presence of NH4Cl. The deduced amino acid sequence of human cathepsin S exhibits a substantial degree of similarity with other human cysteine proteinases and papain indicating that they have a common ancestral gene and are members of a gene family.

Amino Acid Sequence↗
PubMed1992

Endocytosis of different members of the small chondroitin/dermatan sulfate proteoglycan family.

The family of small interstitial chondroitin/dermatan sulfate proteoglycans consists of at least three different molecular species: biglycan (proteoglycan I), decorin (proteoglycan II), and proteoglycan-100, which has a glycosylated core protein of about 100 kDa. The core protein of decorin has been shown to be responsible for receptor-mediated endocytosis of this proteoglycan species by a variety of mesenchymal cells. It is now demonstrated that skin fibroblasts and articular chondrocytes endocytose biglycan with an efficiency similar to that of decorin. Uptake of biglycan is also mediated by its core protein and can be inhibited by decorin in a partially competitive manner. In human fibroblasts, endosomal proteins of 51 and 26 kDa, which are known to bind decorin core protein, also interact with biglycan. This interaction can be inhibited by decorin. Bovine articular chondrocytes contained binding proteins of 48 and 25 kDa. Proteoglycan-100 can be distinguished from biglycan and decorin by its low clearance rate, which however, exceeds the rate of fluid phase endocytosis.

Blotting, Western↗