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Biomedical subjects

M Krause

Publications and source records attributed to M Krause.

At least 19 recordsLinked to original sources
PubMed1992

The pie-1 and mex-1 genes and maternal control of blastomere identity in early C. elegans embryos.

During C. elegans embryogenesis an 8-cell stage blastomere, called MS, undergoes a reproducible cleavage pattern, producing pharyngeal cells, body wall muscles, and cell deaths. We show here that maternal-effect mutations in the pie-1 and mex-1 genes cause additional 8-cell stage blastomeres to adopt a fate very similar to that of the wild-type MS blastomere. In pie-1 mutants one additional posterior blastomere adopts an MS-like fate, and in mex-1 mutants four additional anterior blastomeres adopt an MS-like fate. We propose that maternally provided pie-1(+) and mex-1(+) gene products may function in the early embryo to localize or regulate factors that determine the fate of the MS blastomere.

Animals↗
PubMed1992

Body-wall muscle formation in Caenorhabditis elegans embryos that lack the MyoD homolog hlh-1.

The myoD family of DNA binding proteins has been implicated in the control of myogenesis in a variety of organisms. Searches for homologs in the nematode Caenorhabditis elegans yielded only one gene, designated hlh-1, expressed in body-wall muscle cells and their precursors. To assess the role of hlh-1 in C. elegans myogenesis, genetic deficiencies spanning the hlh-1 locus were isolated after gamma irradiation. Embryos homozygous for these deficiencies exhibited extensive body-wall muscle differentiation, including expression of several characteristic myofilament proteins and weak contracile behavior. Thus, zygotic hlh-1 expression was not required for body-wall muscle precursors to adopt muscle cell fates.

Amino Acid Sequence↗
PubMed1992

Time-dependent regenerative influence of predegenerated nerve grafts on hippocampus.

Our previous studies have revealed that the predegeneration facilitated the neurite outgrowth from hippocampus following the peripheral nerve grafts implantation. The aim of the present work is to find whether the stimulative power of peripheral nerve grafts depends on the time lapse after the transection. Autologous predegenerated distal stumps of the rat sciatic nerves were implanted into the hippocampus on the 7th, 14th, 28th, and 35th day following the transection. Six weeks later, horseradish peroxidase conjugated with fluorescein isothiocyanate was injected into the graft and frozen sections of brains were made. Fluorescence microscope examination has shown that FITC-HRP labeled cells were present among the hippocampal neurons in all the brains under examination, excluding these grafted with 14-day predegenerated peripheral nerves. The FITC-HRP labeled neurons were particularly numerous when the 7- and 35-day-old predegenerated stumps were used as grafts.

Animals↗
PubMed1992

Salmonella typhimurium bacteremia: association with the virulence plasmid.

Virulence plasmids, which are found in a small number of Salmonella serotypes, greatly enhance the extraintestinal growth of salmonellae and lower the LD50 by 2-5 logs in experimental murine infections. To determine if virulence plasmids are important in the pathogenesis of Salmonella bacteremia in humans, blood and fecal isolates of Salmonella typhimurium from California were examined for the presence of a virulence plasmid. Colony blots were done using a labeled probe made from the highly conserved EcoRI fragment of the Salmonella dublin virulence plasmid. A total of 42% of the fecal and 76% of the blood isolates hybridized with the probe. This is the first evidence that the virulence plasmid is important in the pathogenesis of Salmonella bacteremia in humans.

Bacteremia↗
PubMed1992

Epidermal growth factor receptors in porcine endometrium: binding characteristics and the regulation of prostaglandin E and F2 alpha production.

Epidermal growth factor (EGF) and its receptor have been implicated in the control of uterine cell growth and differentiation. The objectives of this study were to determine EGF binding characteristics and effects of EGF on prostaglandin (PG) production in vitro by glandular and stromal cells from porcine endometrium. Endometrial tissues were taken from 10 sows on Day 13 of pregnancy (first day of estrus = Day 0). Glandular and stromal cells were separated by enzymatic dispersion and sieve filtration and cultured for 3 days. EGF-binding assay was carried out at 20 degrees C in the presence of 0.2 nM 125I-EGF with increasing concentrations of unlabeled EGF (0-12 nM). Scatchard analyses revealed one class of high-affinity binding sites in each cell type with apparent equilibrium dissociation constants (n = 6) of 2.96 +/- 0.60 nM and 2.48 +/- 0.50 nM for stromal and glandular cells, respectively. The apparent binding capacities were 199.3 +/- 34.8 fmol/10(6) cells for stromal cells and 40.7 +/- 6.5 fmol/10(6) cells for glandular cells. Effects of EGF on PG production were determined by including 1, 5, 10, or 20 ng/ml EGF in the medium for the final 24 h of the 72-h culture. EGF increased PGE (p less than 0.01) and PGF2 alpha (p less than 0.05) secretion by stromal cells. The highest concentration (20 ng/ml) of EGF increased secretion of PGE and PGF2 alpha by 133% and 64%, respectively, over controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Four homologous domains in the primary structure of GrsB are related to domains in a superfamily of adenylate-forming enzymes.

The entire nucleotide sequence of the Bacillus brevis grsB gene encoding the gramicidin S synthetase 2, which activates and condenses the four amino acids proline, valine, ornithine and leucine has been determined. The gene contains an open reading frame of 13,359 bp which encodes a protein of 4453 amino acids with a predicted Mr of 510,287. The gene is located within the gramicidin S biosynthetic operon, also containing the genes grsT and grsA, whose nucleotide sequences have been determined previously. Within the GrsB amino acid sequence four conserved and repeated domains of about 600 amino acids (45-50% identity) have been identified. The four domains are separated by non-homologous sequences of about 500 amino acids. The domains also share a high degree of similarity (20-70%) with eight peptide synthetases of bacterial and fungal origin as well as with conserved sequences of nine other adenylate-forming enzymes of diverse origin. On the basis of sequence homology and functional similarities, we infer that those enzymes share a common evolutionary origin and present a phylogenetic tree for this superfamily of domain-bearing enzymes.

Amino Acid Isomerases↗
PubMed1992

Evaluation of antihistamine-related daytime sleepiness. A double-blind, placebo-controlled study with terfenadine.

The daytime sleepiness potentially associated with antihistamines was evaluated by the multiple sleep latency test (MSLT) in a study comparing terfenadine with placebo. According to a double-blind, randomized, cross-over design, 12 healthy men were given either 120 mg terfenadine or placebo once daily in the morning, for 3 consecutive days with a 5-day interval. EEG-polygraphic recordings were made each study day at 9:30 and 11:30 a.m., and 1:30, 3:30, and 5:30 p.m., and the tendency to fall asleep was measured. All mean stage-1 sleep latencies throughout the study failed to show any significant difference between terfenadine and placebo. Accordingly, psychomotor performance assessed by visual and auditory reaction time did not change after treatment. The results of this study confirmed that terfenadine does not induce daytime sleepiness as objectively measured by MSLT.

Adult↗
PubMed1992

Regulation of plasmid virulence gene expression in Salmonella dublin involves an unusual operon structure.

The 80-kb plasmid pSDL2 of Salmonella dublin Lane is essential for lethal systemic infection in experimental mice. A cluster of five plasmid genes, designated spvR, spvA, spvB, spvC, and spvD, is sufficient to express the plasmid-related virulent phenotype. The spvR gene product has recently been identified as a positive regulator of spvB expression in the stationary phase of bacterial growth (F. C. Fang, M. Krause, C. Roudier, J. Fierer, and D. G. Guiney, J. Bacteriol. 173:6783-6789, 1991). In this study, we evaluated the role of SpvR in the transcription of the downstream virulence genes spvABCD. Analysis of mRNA synthesis revealed that SpvR promotes transcription of the downstream spvABCD genes in the stationary growth phase. Transcript mapping of the spv region demonstrated an unusual operon structure involving messages for spvA, spvAB, spvABC, and spvABCD. Quantitative measurement of transcription and of gene expression by use of translational spv-lacZ fusions suggested that SpvA, SpvB, SpvC, and SpvD are produced in decreasing abundance. Primer extension assays identified two transcriptional start sites 70 and 98 bp upstream of the start codon of spvA, but none upstream of spvB, spvC, or spvD. Deletion of a 320-bp EcoRI-ApaI segment that contains both start sites abolished expression of the downstream spvB and spvC genes. Our results establish a central function of SpvR as a positive regulator of the downstream spvABCD genes in the stationary phase of bacterial growth and indicate that the primary mechanism of regulation is by activation of promoters upstream of spvA.

Base Sequence↗
PubMed1992

Haemorheological parameters in patients with retinal artery occlusion and anterior ischaemic optic neuropathy.

The haemorheological parameters haematocrit (Hct), plasma viscosity (PV), red cell aggregation (RCA), red cell filterability (RCF), apparent whole blood viscosity (WBV), and fibrinogen were measured in 31 patients with retinal artery occlusion (RAO), 25 patients with anterior ischaemic optic neuropathy (AION), and 19 patients with giant cell arteritis (GCA). The patient groups were compared with controls of same age and similar prevalence of cardiovascular risk factors. Patients with RAO and AION have a significantly decreased RCF in comparison with controls. All other parameters showed no differences. Patients with GCA had significantly decreased Hct and RCF and increased PV and fibrinogen. After 2 weeks of systemic treatment with high dose steroids in patients with GCA the plasma viscosity had returned to normal and was even lower than in controls, and the Hct and fibrinogen had reached normal levels.

Adult↗
PubMed1992

Functional conservation of nematode and vertebrate myogenic regulatory factors.

The Caenorhabditis elegans protein, CeMyoD, is related to the vertebrate myogenic regulatory factors MyoD, myogenin, MRF-4 and Myf-5. Like its vertebrate counterparts, CeMyoD accumulates in the nucleus of striated muscle cells prior to the onset of terminal differentiation. CeMyoD also shares functional similarities with the vertebrate myogenic regulatory factors. Viral LTR driven expression of CeMyoD in mouse 10T1/2 cells can convert this cell line into myoblasts as well as efficiently trans-activate mouse muscle-specific promoters. Furthermore, mouse MyoD expression can activate a CeMyoD-beta-galactosidase reporter construct in a 10T1/2 co-transfection assay.

Amino Acid Sequence↗
PubMed1992

[application of electromyography (EMG) in recognition of lumbo-sacral back pain].

Power spectra of electromyograms (EMG) of back muscles in the lumbo-sacral area were compared in two groups of subjects. In the first one EMGs were registered in 49 young, healthy, males working in standing posture. The recordings were carried out at rest, after application of a 20 kg load and at the onset of pain. In the second group 31 subjects of both sexes and different age, suffering from intense back pain of various etiology, were investigated and compared with a group of 15 healthy persons. In the first group the power level increased after the loading, and in 42 subjects it showed further rise when the pain appeared. In the second group the power level at the range of 25 to 400 Hz, at rest, was significantly higher in the back pain patients than in healthy subjects. The results are discussed from the point of view of their applicability for the diagnosis of back pain.

Adult↗
PubMed1992

The influence of peripheral nerve graft's predegeneration stage on the regrowth of hippocampal injured neurites and concomitant changes in submicrosomal fraction proteins of grafts.

The present work has a twofold aim: 1. To ascertain whether the stimulative influence of peripheral nerve grafts on injured hippocampal neurons depends on the time lapse after transection and; 2. To examine whether the mentioned effect runs parallel to the time-dependent changes of proteins contents and composition in the submicrosomal fraction from transected rat sciatic nerves. Fluorescence microscope examination revealed that FITC-HRP labeled cells extending their neurites into the implanted peripheral nerve segments were particularly numerous among the hippocampal neurons when 7- and 35-day-old predegenegated distal stumps were used as grafts. Discontinuous SDS-slab polyacrylamide gel electrophoresis of submicrosomal fraction proteins obtained from distal stumps of rat sciatic nerves was performed at the 7, 14, 21 and 35 days after transection. Among the obtained protein fractions the most interesting seem to be the ones of 47 and 54 kDa, which reached maximal levels at the 7th day and the 50 kDa fraction with a maximum at the 35th experimental day. It is possible that the growth promoting power of the employed grafts depends on the presence of proper proteins.

Animals↗
PubMed1992

[Bilateral pheochromocytoma. Is there stimulation of an extra-adrenal adrenaline liberation after bilateral adrenalectomy?].

BACKGROUND: In order to determine plasma and urine epinephrine levels after bilateral adrenalectomy, we examined a 16 year old young man with bilateral pheochromocytoma. Bilateral removal of the adrenals was performed because of a left sided pheochromocytoma relapse. An extra-adrenal pheochromocytoma could be excluded by scintigraphy. Macroscopically all adrenal tissue was removed during surgery. METHODS: A modified radioenzymatic determination of the free catecholamines epinephrine, norepinephrine and dopamine was used according to Peuler and Johnson. Sulfoconjugated catecholamines were measured after addition of 60 microU arylsulfatase type VI. Urine catecholamine levels were determined fluorometrically. RESULTS: The elevated plasma andurine norepinephrine levels before surgery returned to normal after surgery. In contrast, plasma epinephrine levels returned to subnormal values thereafter but increases 5-fold at the end of anesthesia suggesting an extra-adrenal source of epinephrine. Urine epinephrine levels remained in the lower normal range. An insulin induced hypoglycemia was performed resulting in adrenergic symptoms of hypoglycemia and a subnormal increase of epinephrine. CONCLUSIONS: We conclude, that epinephrine mediated physiological regulations occur inspite of bilateral adrenalectomy probably by a regulated extra-adrenal source of epinephrine. The kidney could be the site of extra-adrenal epinephrine production.

Adolescent↗
PubMed1992

[Infectious sinusitis and otitis].

Insight into the pathogenesis and knowledge of the microbial flora provide the basis for the treatment of sinus and ear infections. Reduced oxygen tension and impaired mucociliary transport are important factors that influence the pathogenesis of both acute and chronic sinusitis and otitis. Therefore, topical decongestion and antibiotic regimens belong to the main therapeutic principles. The choice of an antibiotic for treatment of acute infections is usually empiric; however, in chronic and recurrent infections identification of the microbiology by fluid aspiration from the sinus or middle ear is desirable before long-term antibiotic therapy is initiated. It is also important to recognize underlying predisposing conditions such as nasal polyps, anatomic deformities or tooth abscesses which should be corrected to prevent further recurrences. External otitis is a painful condition seen most frequently in the swimming season (swimmer's ear) and is often associated with the use of cotton swabs. Repeated removal of debris from of the external canal and ototopical antibiotics are mostly successful; however, in severe cases like in necrotizing external otitis antibiotic therapy is indicated.

Anti-Bacterial Agents↗
PubMed1991

An active serine is involved in covalent substrate amino acid binding at each reaction center of gramicidin S synthetase.

The condensing peptide forming multienzyme of gramicidin S synthetase (gramicidin S synthetase 2) was specifically labeled at its putative thiotemplate sites for L-valine and L-leucine by covalent incorporation of the 14C-labeled substrate amino acids. The thioester complexes of the multienzyme were digested with CNBr, Staphylococcus aureus V8 protease, and pepsin. Reaction center peptides containing the [14C]valine and [14C]leucine labels were isolated in pure form. They show a high degree of sequence similarity and contain the same consensus sequence LGGH/DXL. The labels were eliminated in the first Edman degradation step. A dehydroalanine was identified which can originate from either a cysteine or a serine. The comparison of the chemical results with the deduced amino acid sequence of the grsB gene encoding the gramicidin S synthetase 2 revealed that 4 such motifs are located within the gene structure, each of them being localized in the 3'-terminal region of one of 4 gene segments grsB1-B4. They have a size of approximately 2 kilobases and presumably code for the 4 amino acid activating domains of the synthetase. Surprisingly a serine was found at each putative substrate amino acid-binding position instead of a cysteine as postulated by the thiotemplate mechanism. Therefore the data suggest that active serine residues are involved in nonribosomal peptide syntheses of microbial peptides.

Amino Acid Isomerases↗
PubMed1991

The myoD gene family: nodal point during specification of the muscle cell lineage.

The myoD gene converts many differentiated cell types into muscle. MyoD is a member of the basic-helix-loop-helix family of proteins; this 68-amino acid domain in MyoD is necessary and sufficient for myogenesis. MyoD binds cooperatively to muscle-specific enhancers and activates transcription. The helix-loop-helix motif is responsible for dimerization, and, depending on its dimerization partner, MyoD activity can be controlled. MyoD senses and integrates many facets of cell state. MyoD is expressed only in skeletal muscle and its precursors; in nonmuscle cells myoD is repressed by specific genes. MyoD activates its own transcription; this may stabilize commitment to myogenesis.

Animals↗
PubMed1991

Syllabic stress and the occurrence of stuttering.

The occurrence of stuttering on stress-peak and unstressed syllables in connected speech was studied in 10 young adult stutterers. Results showed a significant coincidence of stutter events and syllabic stress peaks, particularly in polysyllabic words. Stuttering on the first three words of principal clauses, however, appeared independent of syllabic stress. Similarities between the loci of stutter events and segmental errors of speech are considered in relation to explanations that regard stuttering as evidence of failure in normal speech production processes.

Adolescent↗