High-performance liquid chromatographic determination of several quinolone antibacterials in medicated fish feed.
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4-Quinolones↗
Biomedical subjects
A Schmidt
Publications and source records attributed to A Schmidt.
Cloning and nucleotide sequence of the crtI gene encoding phytoene dehydrogenase from the cyanobacterium Aphanocapsa PCC6714.
The membrane-bound phytoene dehydrogenase (PD) is an enzyme in carotenoid biosynthesis which is essential in all microorganisms and plants containing these colored pigments. Despite its key role in the regulation of carotenogenesis, the biochemistry and molecular biology of PD are poorly understood. We have cloned, sequenced and expressed a portion of the PD-encoding gene, crtI, from the blue-green algae Aphanocapsa PCC6714. The gene codes for a 532-amino acids (aa) protein, with a calculated Mr of 52,598 Da. Two regions of the aa sequence share significant homology with PD from the purple bacterium Rhodobacter capsulatus, including a 30-aa region which has been proposed to be specific for dehydrogenases in carotenoid biosynthesis.
Amino Acid Sequence↗
Monte Carlo simulation of the nucleation and growth of binary-alloy particles of Au, Ag, and Pd on NaCl(100) substrates.
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Journal Article↗
A cyclic AMP response element mediates repression of tyrosine aminotransferase gene transcription by the tissue-specific extinguisher locus Tse-1.
Tyrosine aminotransferase (TAT) gene expression is liver specific and inducible by glucocorticoids and via the cAMP signaling pathway. In fibroblasts and other nonliver cells the gene is subject to negative control by the trans-dominant tissue-specific extinguisher locus Tse-1. We identified a hepatocyte-specific enhancer that is repressed by Tse-1. Two distinct sequence motifs are absolutely essential for function of this enhancer: a cAMP response element (CRE), which is the target for repression by Tse-1, and a hepatocyte-specific element. The specificity of the enhancer is generated by the combination of these two essential elements, which are fully interdependent. In vivo footprinting indicates that Tse-1 acts by affecting protein binding at the CRE. A direct antagonism between Tse-1 and the cAMP signaling pathway suggests that Tse-1 plays a role in control of developmental activation of the TAT gene.
Animals↗
Genetic and biochemical characterization of carotenoid biosynthesis mutants of Rhodobacter capsulatus.
We have used genetic and biochemical techniques to study carotenoid biosynthesis (crt) mutants of Rhodobacter capsulatus, a purple non-sulfur photosynthetic bacterium. All nine identified crt genes are located within the 46-kilobase pair photosynthesis gene cluster, and eight of the crt genes form a subcluster. We have studied the operon structure of the crt gene cluster using transposon Tn5.7 mutants. The Tn5.7 insertion sites in 10 mutants have been mapped to high resolution (25-267 base pairs) by Southern hybridization. Two insertions each map within the coding regions of the crtA, crtC, crtE, and crtF genes, and one insertion lies within the crtI gene. The insertion in crtI is not polar on the downstream crtB gene, suggesting that crtI and crtB may form two separate operons. Another insertion located in the 5' noncoding region between the divergent crtA and crtI genes has no effect on wild-type pigmentation and apparently lies between the promoters for these operons. A Tn5.7 mutation in the 3' region of crtA yields a bacteriochlorophyll-minus phenotype, while a 5' insertion affects only carotenoid biosynthesis. Regulatory signals for transcription of a downstream operon required for bacteriochlorophyll biosynthesis may thus overlap the coding region of crtA. We also present the first evidence for the functions of the crtB, crtE, and crtJ gene products using a new in vitro assay for the incorporation of [14C]isopentenyl pyrophosphate into carotenoid precursors and phytoene in cell-free extracts. Extracts from a crtE mutant accumulate [14C]prephytoene pyrophosphate, while those from crtB and crtJ mutants accumulate [14C]geranylgeranyl pyrophosphate. We therefore propose that CrtE is the phytoene synthetase and that CrtB, and possibly CrtJ, are components of the prephytoene pyrophosphate synthetase.
Base Sequence↗
Neurological outcome after a severe herpes simplex encephalitis treated with acyclovir and beta-interferon. Time course of intracranial pressure.
A severe herpes simplex encephalitis with documented intra-cerebral lesions and brain edema was treated successfully with acyclovir and beta-interferon. The increase in intracranial pressure during the second week was well controlled by ICP monitoring. Life-threatening pressure peaks were avoided through the use of thiopental, osmodiuretics, TRIS, and lidocaine.
Acyclovir↗
No difference in expression of chromosomal fragile sites in patients with solid malignant tumours and normal controls.
The frequency and distribution of rare and common chromosomal fragile sites in metaphases derived from peripheral lymphocytes were compared in 26 patients with malignant solid tumours and 24 normal controls. In order to avoid bias in evaluation, the identity of each individual as patient or control was disclosed only after the study was completed. Rare heritable folic acid inducible fragile sites were found in five patients (2q13; 6p23; 8q22; 16p12) and two controls (8q22). Common fragile sites were present in 21 of 26 patients and in 19 of 24 controls. These differences are statistically not significant in the Fisher test. We conclude that the expression of fragile sites does not indicate a predisposition for solid tumours.
Chromosome Fragile Sites↗
Hemodynamic profile of carvedilol.
Several so-called multiple-action compounds have been developed, such as medroxalol (alpha and beta blockade, and beta-2 stimulation), celiprolol (alpha-2 and beta-1 blockade, and beta-2 stimulation) and carvedilol (beta blockade and vasodilatation) for the treatment of patients with arterial hypertension and with coronary heart disease. Carvedilol exerts relatively uniform peripheral effects, i.e. a reduction of both systolic and diastolic blood pressure at rest and during exercise, and a decrease in the resting and exercise heart rate. Blood pressure fall due to carvedilol may be induced by its vasodilating effect, as documented by measurements of forearm blood flow and peripheral vascular resistance. Moreover, renal hemodynamics does not seem to be significantly altered by carvedilol. Carvedilol may also produce an improvement of the LV contractile status in patients with CHD and impaired LV function, mainly due to afterload reduction, in addition to its antianginal effect, which is due mainly to the beta-blocking properties of this substance. From the studies mentioned it may be concluded that carvedilol is a useful and promising drug for treating patients with both arterial hypertension and with coronary artery disease.
Adrenergic beta-Antagonists↗
Bovine arterial smooth muscle cells synthesize two functionally different proteoheparan sulfate species.
Cultured arterial smooth muscle cells synthesize two proteoheparan sulfate species. One is found associated with the cells, whereas the other is excreted into the medium. The two proteoheparan sulfates have similar hydrodynamic sizes but differ in the Mr of their core proteins. The cell-associated proteoheparan sulfate has a Mr of 92,000 while that of soluble proteoheparan sulfate is 38,000. The cell-associated and the soluble proteoheparan sulfate species differ in their ability to suppress the proliferation of smooth muscle cells. When added to the culture medium 2-5 micrograms/ml of the cell-associated and 20-25 micrograms/ml of the soluble proteoheparan sulfate species inhibit the growth of smooth muscle cells half maximally. The antiproliferative potency of both species resides in the heparan sulfate chains. Commercially available heparin has no antiproliferative effect and is not able to prevent the antiproliferative action of cellular heparan sulfate. In contrast to heparin, none of the heparan sulfate preparations has anticoagulant activity. Smooth muscle cells endocytose the soluble heparan sulfate at a rate three to four times higher than that of the cell-associated heparan sulfate. The data suggest that the cell-associated and the soluble proteoheparan sulfate species are separate and possibly genetically distinct molecules. Furthermore, the structural determinants for antiproliferative activity and the recognition sites for endocytotic uptake appear to be different.
Animals↗
Two different proteoheparan sulfate species are synthesized by bovine corneal endothelial cells.
Cultured bovine corneal endothelial cells were labeled with either [35S]sulfate or a combination of [3H]glucosamine and [35S]methionine. The medium proteoheparan sulfate (HS-PG) and cell-associated HS-PG were isolated and identified as heparan sulfate-containing proteoglycans by the susceptibility of their glycosaminoglycan component to specific enzymatic and chemical degradation. The native medium HS-PG has an apparent Mr of about 300,000 and an Mr of its protein core of 64,000, while the native cell-associated HS-PG had a lower molecular weight (approx. 100,000) and an Mr of its protein core of 33,000. The protein core of both HS-PG types consisted of a single polypeptide chain. After beta-elimination reaction of the native HS-PGs the resulting heparan sulfate side chains of medium HS-PG had an Mr of about 60,000, and those of cell-associated HS-PG an Mr of about 30,000. The different molecular parameters of medium HS-PG and cell-associated HS-PG refer to different functional roles. The medium HS-PG secreted by the endothelial cells is regarded as a metabolic precursor of the Descemet's membrane, while the cell-associated HS-PG might represent a cell membrane-integrated proteoglycan.
Animals↗
Incidence and specificity of HLA-DP antibodies in pregnancy sera.
A total of 630 human pregnancy sera were investigated for HLA-DP antibodies (ab) by monoclonal antibody-specific immobilization of leukocyte antigens (MAILA) using monoclonal antibody (mAB) B7/21.2 and selected B-lymphoblastoid cell lines from the Tenth International Histocompatibility Workshop reference panel. DP-specific abs were detected in 86 of 330 sera (26.1%) of a retrospective series selected for positive reactions in lymphocytotoxicity screening, and in 29 of 300 unselected sera (9.7%) of a prospective series. Approximately 80% of DP-reactive sera were also positive in lymphocytotoxicity test for class I and/or class II ab. On the other hand, sera containing lymphocytotoxic ab for both class I and class II ab revealed the highest incidence of DP ab (35%). Out of 115 DP-reactive sera, 28 clearly presented one or more DP specificities. Absorption/elution studies revealed complex patterns of reactivity in some sera which were similar to those of known mABs and possibly reflect supertypic DP specificities and/or serological cross-reactions. Serological DP typing of individuals by the MAILA technique appears promising.
Antibodies, Monoclonal↗
Separate endocytic pathways of kinase-defective and -active EGF receptor mutants expressed in same cells.
Ligand binding to the membrane receptor for EGF induces its clustering and internalization. Both receptor and ligand are then degraded by lysosomal enzymes. A kinase defective point mutant (K721A) of EGF receptor undergoes internalization similarly to the wild-type receptor. However, while internalized EGF molecules bound to either the wild-type or mutant receptors are degraded, the K721A mutant receptor molecules recycle to the cell surface for reutilization. To investigate the mechanism of receptor trafficking, we have established transfected NIH-3T3 cells coexpressing the kinase-negative mutant (K721A) together with a mutant EGF receptor (CD63) with active kinase. CD63 was chosen because it behaves like wild-type EGF receptor with respect to biological responsiveness and cellular routing but afforded immunological distinction between kinase active and inactive mutants. Although expressed in the same cells, the two receptor mutants followed their separate endocytic itineraries. Like wild-type receptor, the CD63 mutant was downregulated and degraded in response to EFG while the kinase-negative mutant K721A returned to the cell surface for reutilization. Intracellular trafficking of EGF receptor must be determined by a sorting mechanism that specifically recognizes EGF receptor molecules according to their intrinsic kinase activity.
Animals↗
Domain deletion in the extracellular portion of the EGF-receptor reduces ligand binding and impairs cell surface expression.
Cultured NIH-3T3 cells were transfected with cDNA constructs encoding human epidermal growth factor-receptor (EGF-R)* and two deletion mutants in the extracellular portion of the receptor molecule. One mutant is devoid of 124 amino-terminal amino acids, and the other lacks 76 residues. Mutant receptors were not delivered to the cell surface unless the transfected cells contained also endogenous EGF-Rs, suggesting that receptor interaction complements the mutation and allows surface display of mutant receptors. Immunoprecipitation experiments revealed an association between mutant and endogenous EGF-Rs when both proteins were expressed in the same cell. Hence, receptor-oligomers may exist in the plane of the membrane even in the absence of ligand binding, and oligomerization may play a role in normal trafficking of EGF-Rs to the cell surface. Mutant receptors retained partial ligand binding activity as 125I-labeled EGF was covalently cross-linked to both mutant receptors, and EGF stimulated, albeit weakly, their protein tyrosine kinase activity. Both mutant EGF-Rs bind EGF with a 10-fold lower affinity than that of the solubilized wild type EGF-R. These results provide further evidence that the region flanked by the two cysteine-rich domains plays a crucial role in defining ligand-binding specificity of EGF-R.
Allosteric Regulation↗
Mapping of proteoglycans in atherosclerotic lesions.
The involvement of sulphated glycosaminoglycans in atherosclerotic changes have been studied in human and rat arteries, and biochemical experiments have revealed that a significant increase in the contents of chondroitin sulphate/dermatan sulphate and cholesterol, but loss of heparan sulphate, occurs in human atherosclerotic arterial tissues. Electron micrographs have revealed that extracellular deposits of lipid are predominantly present in areas rich in chondroitin sulphate proteoglycans but not in areas rich in collagen bundles and dermatan sulphate proteoglycans. The different types of proteoglycans have been distinguished in situ by the cuprolinic blue staining method and enzymatic degradation experiments, and their topohistochemical distribution patterns analysed by morphometry of proteoglycan/cuprolinic blue precipitates. The ultracytochemical investigations indicate changes in size and pattern of chondroitin sulphate-rich proteoglycan-cuprolinic blue precipitates in human atherosclerosis. In plaque tissue, these precipitates are significantly enlarged. In addition, they accumulate around smooth muscle cells in the medial tissue. An increase in the size of proteoglycan-cuprolinic blue precipitates has also been observed in balloon catheter-induced lesions in rat carotid arteries. The large chondroitin sulphate as well as the small dermatan sulphate proteoglycan-cuprolinic blue precipitates show this alteration 2 weeks after balloon injury. We suggest that quantitative and qualitative alterations in the arterial proteoglycans occur in the pathogenesis of atherosclerosis in addition to the cell proliferation and lipid accumulation.
Animals↗
Minimally invasive treatment of ureteric calculi using modern techniques.
Between July 1985 and July 1986, 226 upper and 62 distal ureteric calculi were treated. In situ extracorporeal shockwave lithotripsy (ESWL) is the treatment of choice for upper and distal ureteric calculi, with success rates of 81 and 76% respectively. Retrograde manipulation of the calculus was undertaken only when in situ ESWL was impossible because of difficulty in localisation. Although ESWL after successful mobilisation was successful in 95% of patients, retrograde mobilisation was possible in only 80%. Antegrade ureterorenoscopy via a percutaneous nephrostomy was performed to avoid open surgery if retrograde mobilisation was not feasible, and was successful in 90%. Two second generation lithotripters, the modified Dornier HM3+ and the Wolf Piezolith 2200, both suitable for treatment without anaesthesia, were compared in terms of efficacy. In situ ESWL of upper ureteric calculi was successful in 70.6% with the HM3+ and 37.2% with the Piezolith 2200. In situ ESWL of middle ureteric calculi was successful in 81.8% with the modified HM3+, while in situ treatment of middle ureteric calculi was impossible with the Piezolith 2200 because of inadequate ultrasound localisation. Distal ureteric calculi were treated successfully in 71.4% with the modified Dornier HM3+ and in 64% with the Piezolith 2200. We report our experience of ESWL using the prone position for iliac ureteric calculi; 8 of 10 patients were treated successfully in situ.
Humans↗
In vitro characterization of two different Phycomyces blakesleeanus mutants with impaired phytoene desaturation.
In vitro phytoene desaturation was investigated in two Phycomyces blakesleeanus mutants, C5 and S442, in which phytoene is accumulated instead of beta-carotene. For strain C5 but not strain S442 the phenotypic block of phytoene conversion could be overcome in vitro by the addition of Tween 40. Immunodetection of phytoene desaturase revealed in all cases the presence of a 40-kilodalton protein.
Biotransformation↗
Inducible nuclear factor binding to the kappa B elements of the human immunodeficiency virus enhancer in T cells can be blocked by cyclosporin A in a signal-dependent manner.
Cyclosporin A (CsA) is thought to exert its immunosuppressive effects by inhibiting the expression of a distinct set of lymphokine genes which are induced upon T-cell activation, among them the gene coding for interleukin-2. In addition, the activation of the human immunodeficiency virus (HIV) is partially suppressed. To better understand the molecular mechanisms underlying suppression by CsA, we have investigated the effects of this drug on transcription factors in T cells. Here we report that the formation of two distinct mitogen-inducible DNA-binding complexes, the kappa B complex within the HIV enhancer and the NFAT-1 complex within the interleukin-2 enhancer, is inhibited in the presence of CsA. The kappa B-binding activity with the HIV enhancer is inhibited only if it is activated via the mitogen phytohemagglutinin whereas phorbol myristate acetate-mediated activation is completely insensitive to the drug. This suggests a model in which functionally indistinguishable kappa B complexes can be activated via two separate pathways of signal transduction distinguishable by CsA.
Base Sequence↗
Isolation of mutant Saccharomyces cerevisiae strains that survive without sphingolipids.
Sphingolipids comprise a large, widespread family of complex eucaryotic-membrane constituents of poorly defined function. The yeast Saccharomyces cerevisiae is particularly suited for studies of sphingolipid function because it contains a small number of sphingolipids and is amenable to molecular genetic analysis. Moreover, it is the only eucaryote in which mutants blocked in sphingolipid biosynthesis have been isolated. Beginning with a nonreverting sphingolipid-defective strain that requires the addition of the long-chain-base component of sphingolipids to the culture medium for growth, we isolated two strains carrying secondary, suppressor mutations that permit survival in the absence of exogenous long-chain base. Remarkably, the suppressor strains made little if any sphingolipid. A study of how the suppressor gene products compensate for the lack of sphingolipids may reveal the function(s) of these membrane lipids in yeast cells.
Blotting, Southern↗