Origin of the irreversibility line in thin YBa2Cu3O7- delta films with and without columnar defects.
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Journal Article↗
Biomedical subjects
B Schmidt
Publications and source records attributed to B Schmidt.
Luciferase assembly after transport into mammalian microsomes involves molecular chaperones and peptidyl-prolyl cis/trans-isomerases.
The assembly of a heterodimeric luciferase was studied after de novo synthesis of corresponding precursor proteins in reticulocyte lysate and concomitant transport into dog pancreas microsomes. This cytosolic luciferase from a prokaryotic organism (Vibrio harveyi) was specifically used as a model protein to investigate (i) whether the eukaryotic cytosol and the microsomal lumen have similar folding capabilities and (ii) whether the requirements of a polypeptide for certain molecular chaperones and folding catalysts are determined by the polypeptide or the intracellular compartment. The two luciferase subunits were fused to the preprolactin signal peptide. Data indicate that efficient assembly of luciferase occurs in the mammalian microsomes. Furthermore, it was observed that luciferase assembly can be separated in time from synthesis and membrane transport, depends on ATP hydrolysis, is partially sensitive to cyclosporin A and FK506, and in the absence of lumenal proteins is less efficient as compared with the presence of lumenal proteins. Thus, heterodimeric luciferase depends on functionally related molecular chaperones and folding catalysts during its assembly in either the eukaryotic cytosol or the microsomal lumen.
Adenosine Triphosphate↗
Efficient folding of firefly luciferase after transport into mammalian microsomes in the absence of luminal chaperones and folding catalysts.
Folding of polypeptides emerging from the protein translocase in the membrane of mammalian microsomes was analyzed after synthesis of corresponding precursor proteins in a mammalian translation system. Firefly luciferase was used as a model protein; the corresponding hybrid precursor contained the preprolactin signal peptide. The rates and efficiencies of folding of luciferase in microsomes were compared with those of folding of luciferase in the cytosol. Furthermore, folding of luciferase in microsomes was compared with that in proteoliposomes, i.e. in the absence of luminal molecular chaperones and folding catalysts. Folding in microsomes was less efficient compared with folding in the cytosol. Folding in the absence of luminal proteins was more efficient compared with folding in their presence and identical to folding in the cytosol. Thus, firefly luciferase emerging from translocase can efficiently fold to its native conformation without chaperoning by any luminal proteins. There may be molecular chaperones present in the microsomal membrane that can efficiently substitute for the cytosolic chaperone machinery comprising Hsp40, Hsp60, and Hsp70 with respect to folding of firefly luciferase.
Adenosine Triphosphate↗
Metrifonate improves spatial navigation and avoidance behavior in scopolamine-treated, medial septum-lesioned and aged rats.
We investigated the effects of acute p.o. pretraining treatment with an indirect acetylcholinesterase inhibitor, metrifonate, on water maze spatial navigation and passive avoidance behavior. Metrifonate (10-100 mg/kg, orally, p.o.) did not improve the water maze or passive avoidance performance of young intact rats. However, in young rats metrifonate over a broad dosage range (10-100 mg/kg, p.o.) was able to alleviate the adverse effects of scopolamine (a muscarinic acetylcholine receptor antagonist; 0.4 and 2.0 mg/kg in water maze and passive avoidance study, respectively) and medial septum-lesioning on spatial reference and working memory and passive avoidance performance. In old (23-month-old) rats, a defect of water maze and passive avoidance behavior was observed. In old rats, metrifonate improved spatial reference memory function in the water maze and also passive avoidance at 10-30 mg/kg, but the 3 mg/kg dose was ineffective. Very old (27-month-old) rats had a more severe impairment of water maze performance than old rats, and metrifonate 3-30 mg/kg did not improve their spatial navigation. These results show that metrifonate may over a wide range of doses stimulate cognitive functioning, but during advanced aging neurobiological defects develop that may mask some of the therapeutic effects of metrifonate in rats.
Aging↗
The evolutionary conservation of a novel protein modification, the conversion of cysteine to serinesemialdehyde in arylsulfatase from Volvox carteri.
A novel post-translational protein modification has recently been described in two human sulfatases, by which a cysteine is replaced by a serinesemialdehyde (2-amino-3-oxopropionic acid) residue [Schmidt, B., Selmer, T., Ingendoh, A. & von Figura, K. (1995) Cell 82, 271-278]. This cysteine is conserved among all known eukaryotic sulfatases. Here we report the presence of this modification in arylsulfatase from the green alga Volvox carteri. The evolutionary conservation of this novel protein modification between sulfatases of V. carteri and man lends further support to the assumption that this modification is required for the catalytic activity of sulfatases and may be present in all sulfatases of eukaryotic origin.
Alanine↗
Retinoblastoma protein inhibits IFN-gamma induced apoptosis.
Regulation of apoptosis (programmed cell death) is critical for maintaining tissue homeostasis. Recent studies indicate a tight coupling between cellular proliferation and apoptosis as cell cycle regulators such as Cyclin D, E1A and E7 appear to influence both events. Each of these modulators is able to bind to and inhibit the function of the retinoblastoma tumor suppressor protein (RB). RB functions, in part, by binding to and inactivating E2F transcription factors, preventing expression of E2F-activated genes associated with G1/S cell-cycle progression. Loss of functional RB deregulates E2F activity and, depending on cell type and environmental factors, promotes tumorigenesis or apoptotic death. To determine the effect of RB on IFN-gamma induced apoptosis, we treated RB-defective carcinoma cell lines and their respective RB-constituted sister clones with IFN-gamma and examined the cells for alterations characteristic of apoptosis. We observed that RB-defective cells, but not the RB-reconstituted clones, decreased in size following IFN-gamma treatment. IFN-gamma treatment caused increased cell detachment in the RB-defective lines but did not affect adherence of the RB-reconstituted clones. Assays for DNA fragmentation revealed lower molecular weight DNA and the apoptosis-associated oligo-nucleosomal ladder following IFN-gamma treatment of the RB-defective cells while higher molecular weight DNA was present in the IFN-gamma treated, RB-reconstituted lines. IFN gamma-induced apoptosis in RB-defective cells was enhanced by serum stimulation, which is also characteristic of p53-dependent E2F-1-mediated apoptosis. However, IFN-gamma induced apoptosis in RB-defective lines does not require wild-type p53 suggesting that, upon IFN-gamma induction, deregulated E2F-mediated apoptosis can also proceed via p53-independent pathways.
Antineoplastic Agents↗
An indirect cholinesterase inhibitor, metrifonate, increases neocortical EEG arousal in rats.
We investigated the ability of a cholinesterase inhibitor, metrifonate, to desynchronize cortical EEG activity. Metrifonate suppressed immobility-related high voltage spindling activity in young and aged rats at doses of 30 and 60 mg kg-1, p.o., and 10, 30 and 60 mg kg-1, p.o., respectively. The increase in EEG 1-20 Hz amplitude induced by scopolamine (0.2 mg kg-1, i.p.) was fully alleviated by metrifonate (30 and 100 mg kg-1, p.o.) and partially alleviated by a reference cholinesterase inhibitor, THA (3 and 6 mg kg-1, i.p.). Nucleus basalis (NB) lesions induced by quisqualic acid decreased frontal cortical choline acetyltransferase activity by 80% and increased cortical EEG slow waves. Metrifonate and THA did not reverse NB lesion-induced EEG abnormality. We conclude that metrifonate enhances cholinergic desynchronization of cortical EEG waves and that a severe defect of presynaptic NB cholinergic fibres limits the therapeutic effects of metrifonate.
Animals↗
Molecular evidence for transmission of hepatitis G virus by blood transfusion.
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Adult↗
Role of microglia and host prion protein in neurotoxicity of a prion protein fragment.
The prion protein PrPc is a glycoprotein of unknown function normally found in neurons and glia. It is involved in diseases such as bovine spongiform encephalopathy (BSE), scrapie and Creutzfeldt-Jakob disease. PrPSc, an altered isoform of PrPC that is associated with disease, shows greater protease resistance and is part of the infectious agent, the prion. Prion diseases are characterized by neuronal degeneration, gliosis and accumulation of PrPSc. Mice devoid of PrPC are resistant to scrapie. A fragment of human PrP consisting of amino acids 106-126 that forms fibrils in vitro is toxic to cultured neurons. Here we show that this toxic effect requires the presence of microglia which respond to PrP106-126 by increasing their oxygen radical production. The combined direct and microglia-mediated effects of PrP106-126 are toxic to normal neurons but are insufficient to destroy neurons from mice not expressing PrPC.
Amino Acid Sequence↗
Occurrence of polyhydroxyalkanoic acid granule-associated proteins related to the Alcaligenes eutrophus H16 GA24 protein in other bacteria.
Fifty different polyhydroxyalkanoic acid (PHA)-accumulating bacterial strains were investigated for the occurrence of phasin proteins bound to PHA granules and related to the GA24 protein of Alcaligenes eutrophus H16, by isolating PHA granules and Western blot analysis of granule-associated proteins employing antibodies raised against the GA24 protein. It could be demonstrated that th PHA granules of many poly(3-hydroxybutyrate)-accumulating bacteria exhibited a similar protein pattern, and a predominant protein of 24 +/- 2 kDa occurred in the granules of A. eutrophus strains A7, CH34, JMP222, N9A and TF93 exhibiting N-terminal amino acid sequences identical to that of the GA24 protein. Proteins bound to the granules of A. latus, Burkholderia caryophyli, B. cepacia, B. solanacearum, Pseudomonas glathei, Rhodobacter sphaeroides and Telluria mixta also gave positive immunoreactions. Granule-associated proteins of small size also occurred in various strains of the Gram positive bacteria Bacillus megaterium and R. ruber as well as in the Gram-negative bacteria Azotobacter sp., Chromatium vinosum, Comamonas acidovorans, Methylobacterium sp., Mycoplana rubra, Paracoccus denitrificans, Pseudomonas sp., Rhodospirillum rubrum, Rubrivivax gelatinosus and Thiocystis violacea; however, they gave no immunoreaction. This study clearly demonstrated that phasins are wide-spread if not essential in PHA-accumulating bacteria.
Alcaligenes↗
Inflammatory infiltrates in sural nerve biopsies in Guillain-Barre syndrome and chronic inflammatory demyelinating neuropathy.
Prompted by observations in experimental autoimmune neuritis we reanalyzed immunohistochemically the inflammatory infiltrates in sural nerve biopsies of 22 cases with Guillain-Barre syndrome (GBS) and 13 cases with chronic inflammatory demyelinating polyneuropathy (CIDP). Endoneurial infiltration of CD3+ T cells was found in 20 cases of GBS (median 5.5 cells/mm(2)) and in 10 cases of CIDP (5 cells). Epineurial T cells were present in all GBS cases (19.5 cells) and in 11 CIDP cases (21 cells). CD68+ macrophages were abundant in these neuropathies and often occurred in endoneurial perivascular clusters. In GBS subgroups the number of endoneurial T cells was significantly higher in patients with hypoesthesia and abnormal electrophysiological findings in the sural nerve. In CIDP hypoesthesia was associated with significantly higher numbers of macrophages. Our study also indicates that other factors including the time point of biopsy or previous corticosteroid treatment may influence the inflammatory cell profile. Quantifying cell infiltration may aid in establishing the diagnosis of an immunoneuropathy in patients with mild and noncharacteristic pathology.
Adult↗
Mutation analysis of phenylketonuria in south Brazil.
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Alleles↗
A neurotoxic prion protein fragment enhances proliferation of microglia but not astrocytes in culture.
The scrapie isoform of the prion protein (PrPSc) induces pathological changes in the central nervous system including neurodegeneration and gliosis. A synthetic prion protein (PrP) peptide corresponding to amino acid residues 106-126 has been shown to be toxic to neurons that express PrPC, the cellular isoform of PrP. Here we show that in mixed glial cultures PrP106-126 induces astroglial proliferation that is dependent on cellular PrPc expression. In purified cultures of glial subtypes only microglia proliferated in response to PrP106-126. This effect was independent of PrP expression. Destruction of microglia in mixed glial cultures by L-leucine methyl ester (LLME) treatment abolished enhanced proliferation caused by PrP106-126. This proliferative effect can be restored by co-culturing LLME-treated astrocytes with microglia. Microglia therefore seem to mediate the proliferative effect exerted by PrP106-126 on astrocytes.
Amino Acid Sequence↗
Donor heart quality control. Analysis of echocardiographic (EC) findings and patient outcome.
In a retrospective analysis, 149 echocardiographic (EC) evaluations were compared with conventional clinical parameters for donor heart selection. Of these cases, 12% were found with severe impairment of ventricular wall motion or with morphological abnormalities. Nearly half of the echocardiographically diagnosed pathological findings in donor hearts were not detected by conventional standards for heart screening. Analysis of EC-screened donor heart outcome showed a primary graft nonfunction rate of 3.1%. We suggest EC as an additional screening instrument for further dynamic and morphological information about donor heart condition. Potential donors can be saved for transplantation and severe complications can be avoided by detecting occult cardiac dysfunction. Early detection of cardiac dysfunction may have an impact on donor therapy and can avoid unnecessary and expensive transportation of the surgical team to the harvest site.
Adolescent↗
Differential diagnosis of postoperative liver failure in a 12-year-old child.
The case of a 12-year-old child who died of fulminant hepatic failure a few days after tonsillectomy is reported. Histological examination revealed large areas of massive centrilobular hepatic necrosis. Hepatotoxicity of postoperatively administered paracetamol in high dosages combined with enflurane exposure is discussed as a cause for the hepatic failure. The fulminant clinical course could have been influenced by an infection with hepatitis G virus which was detected in liver tissue by in situ hybridisation and was probably transmitted via transfusion of blood plasma.
Acetaminophen↗
OK-432 therapy of lymphangiomas in children.
UNLABELLED: Between April 1988 and July 1995, 11 children with lymphangioma were treated with intralesional OK-432 injection. In 7 patients it was the primary therapy and total shrinkage of the lesion was obtained in 5 of them. Two patients did not respond and the children underwent surgery. Following incomplete surgical removal or recurrence of the lymphangioma, intralesional OK-432 injection was used as secondary therapy in 4 patients. Total regression was observed in 2 cases and marked regression in the 2 others. No serious side-effects except fever lasting for 2-3 days and slight tenderness with swelling of the lymphangioma for 3-4 days after the injection was noted. Local inflammatory reaction did not cause any damage to the overlying skin and did not lead to scar formation. Depending on the size, location, and anatomical relationship of the airway, intralesional injections of the lymphangiomas were performed under general anaesthesia and the children were observed for 24 h. There was no recurrence after follow up periods ranging from 2 months to 7 years. CONCLUSION: Intralesional injection OK-432 represents an alternative, safe and effective treatment for lymphangiomas. It can be used as the primary therapy, after partial surgical excision, or in recurrent lymphangiomas.
Antineoplastic Agents↗
Urinary antigens as markers of papillary toxicity. I. Identification and characterization of rat kidney papillary antigens with monoclonal antibodies.
Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells as ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150-200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The monoclonal antibodies prepared and the tests developed thus may provide direct diagnostic access to the renal papilla and allow, for the first time, early detection of papillary damage.
Animals↗