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Biomedical subjects

C Klein

Publications and source records attributed to C Klein.

At least 199 records · Page 11Linked to original sources
PubMed1998

Dictyostelium discoideum Hsp32 is a resident nucleolar heat-shock protein.

Hsp32 is a small shock protein in Dictyostelium discoideum that is expressed in growing cells in the absence of heat shock. Here we show that Hsp32 is an Ag-NOR-staining protein capable of binding DNA with high affinity. Hsp32 is also shown to be a resident nucleolar protein both under normal growth conditions and during heat stress. In unstressed cells, Hsp32 localizes to the nucleolar periphery in a pattern reminiscent of the rDNA in this organism. During the first several hours of heat shock, the peripheral localization of Hsp32 is not altered, although rDNA transcription is arrested. Prolonged heat shock causes a condensation of the rDNA. Under these conditions, Hsp32 is no longer predominantly associated with the rDNA, but is instead distributed over the entire nucleolus. Hsp32 therefore retains ist nucleolar localization under prolonged heat shock conditions by associating with nucleolar components other than the rDNA or rRNA.

Animals↗
PubMed1998

Elevated adhesiveness/aggregation of peripheral blood leukocytes in patients with major depression.

A simple slide test was used to determine the effects of major depression (MD) and heterocyclic antidepressants on leukocyte adhesiveness/aggregation (LAA) in the peripheral blood. Eighty subjects were categorized into four equal groups: untreated-MD patients, treated-MD patients, nondepressed patients treated with antidepressants and healthy controls. Significantly higher LAA values were observed both in untreated- and treated-MD patients, 13.8+/-1.7% and 13.5+/-1.9% respectively, compared to nondepressed-treated patients and healthy controls, 5.4+/-0.9% and 6.4+/-0.7% respectively (P < 0.0001). Increased LAA was associated with the depressive episode, was not affected by antidepressants and may potentially serve as a useful laboratory state marker for MD.

Adult↗
PubMed1998

Topography of CNV and PINV in schizotypal personality.

The topography of the postimperative negative variation (PINV) was analyzed in participants with high and low scores on the German version of the Schizotypal Personality Questionnaire. Scalp amplitude and Laplacian maps of the terminal contingent negative variation (tCNV) and PINV and the time course of the PINV were compared between the two groups. CNV and PINV were induced with a delayed matching-to-sample task, in which the pattern of the imperative stimulus was either clearly or ambiguous matched to one of the two diamonds simultaneously presented as a warning stimulus 4.0 s earlier. Electroencephalograms were recorded with a DC amplifier (32 channels). Negativity increased from tCNV to PINV, especially at frontal sites, and the PINV was larger under ambiguous than under clear matching conditions. Low-scoring participants showed a right-sided predominance of the PINV, which was absent in high-scoring participants. These results resemble differences in the topography of the PINV between healthy control participants and those with schizophrenia under identical experimental conditions and suggest functional differences between tCNV and PINV.

Adult↗
PubMed1998

Identification of surrogate agonists for the human FPRL-1 receptor by autocrine selection in yeast.

We describe a procedure for isolating agonists for mammalian G protein-coupled receptors of unknown function. Human formyl peptide receptor like-1 (FPRL-1) receptor, originally identified as an orphan G protein-coupled receptor related to the formyl peptide receptor (FPR1), was expressed in Saccharomyces cells designed to couple receptor activation to histidine prototrophy. Selection for histidine prototrophs among transformants obtained with a plasmid-based library encoding random peptides identified six different agonists, each of whose production yielded autocrine stimulation of the receptor expressed in yeast. A synthetic version of each peptide promoted activation of FPRL-1 expressed in human embryonic kidney (HEK293) cells, and five of the peptides exhibited significant selectivity for activation of FPRL-1 relative to FPR1. One selective peptide was tested and found to mobilize calcium in isolated human neutrophils. This demonstrates that stimulation of FPRL-1 results in neutrophil activation and suggests that the receptor functions as a component of the inflammatory response. This autocrine selection protocol may be a generally applicable method for providing pharmacological tools to evaluate the physiological roles of the growing number of mammalian orphan G protein-coupled receptors.

Amino Acid Sequence↗
PubMed1998

Search for a founder mutation in idiopathic focal dystonia from Northern Germany.

Both the discovery of the DYT1 gene on chromosome 9q34 in autosomal dominant early-onset torsion dystonia and the detection of linkage for one form of adult-onset focal dystonia to chromosome 18p (DYT7) in a family from northern Germany provide the opportunity to further investigate genetic factors in the focal dystonias. Additionally, reports of linkage disequilibrium between several chromosome 18 markers and focal dystonia, both in sporadic patients from northern Germany and in members of affected families from central Europe suggest the existence of a founder mutation underlying focal dystonia in this population. To evaluate the role of these loci in focal dystonia, we tested 85 patients from northern Germany who had primary focal dystonia, both for the GAG deletion in the DYT1 gene on chromosome 9q34 and for linkage disequilibrium at the chromosome 18p markers D18S1105, D18S1098, D18S481, and D18S54. None of these patients had the GAG deletion in the DYT1 gene. Furthermore, Hardy-Weinberg analysis of markers on 18p in our patient population and in 85 control subjects from the same region did not support linkage disequilibrium. Taken together, these results suggest that most cases of focal dystonia in patients of northern German or central European origin are due neither to the GAG deletion in DYT1 nor to a proposed founder mutation on chromosome 18p but must be caused by other genetic or environmental factors.

Age of Onset↗
PubMed1998

Heat shock alters poly(A) tail length of Dictyostelium discoideum hsp32 RNA.

Hsp32 is a heat shock gene in D. discoideum. We have previously observed that heat stress-induced change produces a broad band on Northern blots, suggesting that more than one population of mRNA is present under those conditions. This was not the result of a defect in the splicing of the hsp32 mRNA, nor did it result from the use of a different transcription start site under heat shock conditions. Here, we show that the broad banding pattern reflects the appearance of a transcript with a poly(A) tail that is approximately 100 nt longer than that seen in unstressed cells. Experiments indicated that this tail was not a property of newly synthesized mRNA but rather a response to heat stress. This response appeared to be specific to the hsp32 transcript and did not result in the retention of the RNA in the nucleus. These results document a relatively unusual heat shock response and also indicate that the nature of the response differs among RNAs and has selective consequences.

Animals↗
PubMed1998

The three-dimensional study of chromosomes and upstream binding factor-immunolabeled nucleolar organizer regions demonstrates their nonrandom spatial arrangement during mitosis.

The volumic rearrangement of both chromosomes and immunolabeled upstream binding factor in entire well-preserved mitotic cells was studied by confocal microscopy. By using high-quality three-dimensional visualization and tomography, it was possible to investigate interactively the volumic organization of chromosome sets and to focus on their internal characteristics. More particularly, this study demonstrates the nonrandom positioning of metaphase chromosomes bearing nucleolar organizer regions as revealed by their positive upstream binding factor immunolabeling. During the complex morphogenesis of the progeny nuclei from anaphase to late telophase, the equal partitioning of the nucleolar organizer regions is demonstrated by quantification, and their typical nonrandom central positioning within the chromosome sets is revealed.

Chromosomes↗
PubMed1998

De novo mutations (GAG deletion) in the DYT1 gene in two non-Jewish patients with early-onset dystonia.

The DYT1 gene recently has been cloned and shown to contain a three nucleotide (GAG) deletion responsible for most cases of autosomal dominant early-onset torsion dystonia. This deletion results in the loss of one of a pair of glutamic acids in a conserved region of a novel ATP-binding protein (torsinA). Previous haplotype analysis revealed that this same deletion had arisen at least two different times in history, suggesting independent mutational events. This deletion is the only sequence change found thus far to be associated uniquely with the disease status, regardless of ethnic origin. Here we describe two patients with typical early-onset torsion dystonia of Swiss-Mennonite and non-Jewish Russian origin, respectively, that both carry this same mutation as a de novo GAG deletion. This finding proves that this 3 bp deletion in the DYT1 gene is indeed a mutation that causes early-onset torsion dystonia. The DYT1 mutation is one of the rare examples of the same recurrent mutation causing a dominantly inherited condition. The sequence surrounding the GAG deletion contains an imperfect 24 bp tandem repeat, suggesting a possible mechanism for the high frequency of this mutation.

Adult↗
PubMed1998

Development of a quantitative vancomycin immunoassay for the Abbott AxSYM analyzer.

A novel fluorescence polarization immunoassay for vancomycin on Abbott AxSYM analyzer is described. The immunoassay allows for the accurate quantification of vancomycin in the presence of the crystalline degradation product (CDP). It displays dilution linearity from 1.0 microg/ml to 100.0 microg/ml, coefficients of variation ranging from 2.94% to 4.26%, recovery from 98% to 105%, and a sensitivity of <2.0 microg/ml. The assay demonstrates no cross-reactivity to crystalline degradation product, and to commonly-prescribed and over-the-counter drugs, as well as a minimum interference from endogenous substances.

Animals↗
PubMed1998

Quantified EEG in patients with vertigo of central or peripheral origin.

Computerized EEG frequency analysis was performed in 18 patients with peripheral vestibular dysfunction (PVD), 17 patients with central vestibular dysfunction (CVD) and 22 aged matched controls. Increase in the relative theta activity in the centrotemporal region was found in patients with PVD. The decrease of centroparietal beta activity in both groups of patients, as compared to controls, did not reach statistical significance. We conclude that quantified EEG may be a sensitive method to show changes of cortical electrical activity in patients with vertigo, reflecting the imbalance in afferent vestibular input to the cortex.

Adult↗
PubMed1998

Cloning of the Xenopus integrin alpha(v) subunit and analysis of its distribution during early development.

One striking feature of the integrin alpha(v) subunit is its ability to associate with at least five different beta subunits (beta1, beta3, beta5, beta6 and beta8) to form functional receptors. These receptors are involved in diverse biological processes, such as differentiation, cell adhesion and migration. Here we report the cloning of the Xenopus homolog of the integrin alpha(v) subunit. Integrin alpha(v) mRNA and protein are maternally supplied and present throughout development. During gastrulation and neurulation alpha(v) protein appears on cell membranes of all three germ layers. In tailbud stage embryos great amounts of the alpha(v) protein can be observed in the inner layer of the ectoderm and in the endothelial cells lining the pharynx and gut.

Amino Acid Sequence↗
PubMed1998

Effects of nitric oxide on adenylyl cyclase stimulation in N18TG2 neuroblastoma cells.

The addition of nitric oxide (NO), in the form of either donor compounds or nitric oxide gas, inhibits hormone-stimulated cAMP accumulation in N18TG2 cells. Hormone receptors and Gs are not targets of NO because forskolin-stimulated cAMP accumulation is also inhibited. The inhibitory effect of NO is not altered by pretreatment of cells with pertussis toxin, indicating that Gi is not mediating the effect of NO. cAMP accumulation in these cells is not altered by cell incubation with Ca++ ionophore or calmidazolium, indicating that calmodulin is not the target for NO. Experiments also rule out changes in phosphodiesterase or cGMP as mediators of the effect of NO. Cell incubation with superoxide dismutase in the presence or absence of catalase indicate that nitric oxide is the reactive species. The inhibitory action of nitric oxide is readily reversed, allowing full recovery of hormone and forskolin stimulation within 20 min of incubation in the absence of nitric oxide. The sum of the data indicate that NO targets either the adenylyl cyclase itself, or a regulatory component distinct from G proteins or calmodulin, to inhibit activation of the enzyme.

Adenylyl Cyclase Inhibitors↗
PubMed1998

Pathological laughter: common vs. unusual aetiology and presentation.

Pathological laughter and crying is a well known clinical phenomenon which in most cases appears in association with diverse neurological and psychiatric symptoms and signs. It is not a disturbance of affectivity but rather of the motor concomitant of affective expression. Its main clinical characteristics are: absence of voluntary control and absence of the corresponding change in mood. It is not accompanied by the emotional lability of the organic brain syndromes, it does not present the inappropriate jocularity of the patients with frontal lobe disturbance, it is not due to the intoxicating effect of alcohol or addictive drugs and there are no typical symptoms of manic syndromes (such as grandiose self-esteem, flight of ideas, hyperactivity, etc.). In this paper three cases of pathological laughter are presented, two of these associated with organic brain conditions. The discussion will deal in particular with aetiological considerations and psychopathology of the third case which was unusual because it was a monosymptomatic condition and seemed to be the expression of a posttraumatic stress disorder.

Adult↗
PubMed1997

Developmental regulation of Hsp32, a small heat shock protein in Dictyostelium discoideum.

We have examined the expression and heat inducibility of Hsp32, a novel small heat shock protein in Dictyostelium discoideum. Both Hsp32 and its mRNA are abundant in amoebae growing at physiological temperatures. Levels of Hsp32 remain high during the initial phases of development, including the formation of tipped mounds. After that stage, Hsp32 levels decrease, reaching barely detectable levels in culminating cells. In contrast, most of the hsp32 mRNA is rapidly degraded within the first few hours of starvation-induced development. Cells retain a new low steady state level of the mRNA throughout the rest of the developmental cycle. However, when cells undergo dedifferentiation, they reaccumulate high levels of hsp32 mRNA just prior to cell division. The heat inducibility of Hsp32 and its mRNA is maximal in growing cells and decreases as cells progress in their developmental program. The data suggest that Hsp32 is associated with a growth and/or survival function that is gradually eliminated during development.

Animals↗
PubMed1997

The complete genome sequence of the gram-positive bacterium Bacillus subtilis.

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.

Bacillus subtilis↗
PubMed1997

Multiple levels of regulation of Escherichia coli succinyl-CoA synthetase.

Concentrations of GDP, which are expected to bind to the catalytic site and inhibit the autophosphorylation of succinyl-CoA synthetase (SCS) when NTP is used as a substrate, were found to increase the level of phosphoenzyme formed. The ability of GDP to do so is dependent upon the presence of a protein distinct from SCS. The effector protein could be separated from SCS by ammonium sulfate fractionation. Reconstitution experiments show that the protein inhibits SCS, that the inhibition is relieved by GDP, and that the inhibitor recognizes both Escherichia coli and eukaryotic forms of SCS. The inhibitor is itself regulated by the conditions used to grow the bacteria and in a manner that appears distinct from that of SCS.

Adenosine Diphosphate↗
PubMed1997

Cloning, structural analysis and expression of the gene encoding Hsp32 from Dictyostelium discoideum.

We have isolated and characterized genomic clones encoding a novel small heat shock (HS) protein (Hsp32) from Dictyostelium discoideum that is not homologous to the alpha-crystallin family Hsps. Besides its induction by HS, this gene is also regulated during the life cycle of the organism. At physiologic temperatures hsp32 is expressed at high levels in growing cells and at low levels in cells starved to initiate their developmental programme. However, in both cases the gene can be induced by HS. A DNA fragment containing the upstream region of hsp32 was shown to confer HS induction to a cat reporter gene, indicating a transcriptional regulation for this gene. A single transcription start site, located at position -152 relative to the initiator Met, 17 nucleotides downstream from a putative TATA box, was determined both in vegetative cells and cells starved for 6 h. This site was unchanged when either vegetative or starved cells were submitted to HS at 30 degrees C for 30 min. Despite HS induction, a perfect HSE element was not found in the 5' regulatory region of the gene. The hsp32 coding region is interrupted by a single intron located near its 5' end, which is properly spliced even under HS conditions.

Amino Acid Sequence↗