Search PubMed⌕ Search

Biomedical subjects

P Kaiser

Publications and source records attributed to P Kaiser.

At least 73 records · Page 4Linked to original sources
PubMed1995

Avian coccidiosis: changes in intestinal lymphocyte populations associated with the development of immunity to Eimeria maxima.

The effect of infection and subsequent challenge with Eimeria maxima on the populations of lymphocytes in the small intestine of Light Sussex chickens was assessed by immunohistochemistry. T cells were characterized for CD3, CD4, CD8, TCR1 (gamma delta heterodimer) or TCR2 (alpha beta 1 heterodimer) markers, and B cells for the expression of IgM, IgA and IgG. After a primary inoculum there were, in both the epithelium and the lamina propria, two distinct increases in the numbers of T lymphocytes. The first peaked on days 3-5 and the second, greater influx, on day 11 after infection. CD4+ and CD8+ cells were represented in both peaks but, whereas CD4+ cells were found almost exclusively in the lamina propria, CD8+ cells were present in both sites. The area staining positive for CD8+ cells was somewhat greater than the value obtained for CD4+ cells. In the epithelium there was an early, small increase in TCR1(+)-staining, followed by a larger rise to the second peak, at which time there was also an increase in the lamina propria. Staining for TCR2+ cells followed the same pattern with a reversed distribution between epithelium and lamina propria. Changes after challenge were minimal and confined to the epithelium. The most notable changes in the expression of immunoglobulins were, in the lamina propria, a biphasic increase in the amount of IgM(+)-staining in the course of primary infection (corresponding approximately to that of the T cells), and in IgA+ cells shortly after challenge.

Animals↗
PubMed1995

Anti-vascular endothelial cell antibodies (AECA): comparison of two assay methods and clinical applications.

Vascular endothelial cells may be a target for autoantibodies (AECAs) against membrane antigens that are constitutively expressed, induced or bound to their surface. To test this hypothesis, we used an enzyme-linked immunosorbent assay (ELISA) with two types of human endothelial cells as the substrate, i.e., human umbilical cord vein endothelial cells (HUVECs) or the hybrid cell line EAhy-926 obtained by fusion of HUVECs with the bronchial carcinoma cell line A549. A comparative functional study of these two cell types demonstrated that EAhy-926 cells produced only small amounts of VIII von Willebrand factor and tissular factor, did not contain Weibel Palade bodies visible under the electron microscope, and expressed ICAM-1 and selectin E in levels of no more than 15% of those expressed by human umbilical cord vein endothelial cells both after stimulation by bacterial lipopolysaccharide and under basal conditions. However, the two assay methods yielded similar IgG AECA titers when used on sera from patients with rheumatoid vasculitis or antiphospholipid syndrome. These antibodies did not exhibit cytotoxicity for cord vein or EAhy-926 cells. They were not specific for endothelium, since their activity decreased by a mean of 40% after incubation of sera with the epithelial cell line A549. A cross-sectional study of 565 sera demonstrated that anti-vascular IgG and IgM AECAs reactive with EAhy-926 cells occurred mainly in patients with dermatomyositis (IgG, 58%; IgM, 22%), systemic scleroderma (IgG, 48%; IgM, 18%), primary Sjögren's syndrome (IgG, 44%; IgM, 12%) and secondary and primary systemic vasculitides (IgG, 38%; IgM, 18%) including Wegener's granulomatosis. A longitudinal study in patients with Wegener's granulomatosis showed that AECAS were predictive of disease activity.

Antibodies↗
PubMed1994

The human ubiquitin-conjugating enzyme UbcH1 is involved in the repair of UV-damaged, alkylated and cross-linked DNA.

The human ubiquitin-conjugating enzyme UbcH1 shows 69% identity to the Saccharomyces cerevisiae RAD6/UBC2 which plays a key role in DNA repair. To examine the function of UbcH1 (formerly named E2, M(r) 17,000), [(1990) EMBO J. 9, 1431-1435]) we tested its ability to functionally substitute for yeast RAD6/UBC2 in the recovery of cells from various DNA damage. Complementation by expression of the human UbcH1 cDNA revealed that the UbcH1 carries out the function of S. cerevisiae RAD6/UBC2 in the repair of UV-damaged, alkylated and cross-linked DNA.

Alkylation↗
PubMed1994

A human ubiquitin-conjugating enzyme homologous to yeast UBC8.

Ubiquitin-conjugating enzymes catalyze the covalent attachment of ubiquitin to cellular substrates. Here we describe the isolation of a novel ubiquitin-conjugating enzyme from human placenta and the cloning of the corresponding cDNA. DNA sequencing revealed that this gene, UbcH2, encodes a protein with significant sequence similarity to yeast UBC8. In contrast to a previous report (Qin, S., Nakajima, B., Nomura, M., and Arfin, S. M. (1991) J. Biol. Chem. 266, 15549-15554), we discovered that UBC8 is interrupted by a single intron bearing an unusual branch point sequence. The revised amino acid sequence of yeast UBC8 exhibits 54% amino acid sequence identity to human UbcH2. Moreover, full-length UbcH2 and UBC8 enzymes expressed from their cDNAs show similar enzymatic activities in vitro by catalyzing the ubiquitination of histones, suggesting that the two enzymes may fulfill similar functions in vivo. Interestingly, comparison of the enzymatic activities of a truncated UBC8 (Qin, S., Nakajima, B., Nomura, M. and Arfin, S. M. (1991) J. Biol. Chem. 266, 15549-15554) and of the full-length enzyme (this report) suggests, that the first 12 amino-terminal residues of UBC8 are required for ubiquitination of histones in vitro but not for thiolester formation with ubiquitin. This suggests that the NH2 terminus of UBC8 may be necessary either for substrate recognition or for the transfer of ubiquitin onto substrates. The UbcH2 gene is located on chromosome 7 and shows a complex expression pattern with at least five different mRNAs.

Amino Acid Sequence↗
PubMed1993

Large genomic rearrangements of the unstable region in Streptomyces ambofaciens are associated with major changes in global gene expression.

Global gene expression is dramatically altered by genomic rearrangements in Streptomyces ambofaciens RP181110. Partial genome mapping of two derivatives of strain RP181110 (strains NSA205 and NSA228) revealed rearrangements located in the unstable region of the genome (deletion in strain NSA228; deletion and amplification in strain NSA205). Computerized comparisons of pulse-labelled proteins separated by two-dimensional electrophoresis have revealed numerous differences in gene expression among the three strains during both exponential and stationary phases of growth: 31 proteins were absent in both mutant strains, 16 were absent only in strain NSA228, 17 were absent only in strain NSA205 and 9 were found to be present or overexpressed in strain NSA205. Thus, in spite of the scarcity of genetic markers in the unstable region and its dispensability for growth under laboratory conditions, these results suggest that it includes genes which are actively expressed. Spontaneous gene amplifications, which occur frequently in this region of the chromosome, can further activate their expression.

Bacterial Proteins↗
PubMed1993

Characterization of dinY, a new Escherichia coli DNA repair gene whose products are damage inducible even in a lexA(Def) background.

Bacteriophage Mu dX(Ap lac) was used to isolate a mutation in an Escherichia coli lexA(Def) strain representing a previously undescribed gene (dinY) which does not seem to be under the direct control of LexA. The insertion created a dinY::lacZ fusion in which beta-galactosidase expression required a DNA-damaging treatment (UV irradiation or mitomycin) and activable RecA protein. This strain showed a decreased Weigle reactivation of bacteriophage lambda. However, it was fully inducible for UV mutagenesis. Two-dimensional gel electrophoresis analysis identified two spots absent in the mutant which were both UV inducible only in the presence of activated RecA protein (RecA*). This finding suggests that the dinY::lacZ fusion lies in a gene either that is under the direct control of activated RecA or whose product undergoes RecA*-dependent posttranscriptional/posttranslational modification(s). The dinY gene may also control the expression of some other gene(s) and/or lie in an operon. The fusion was mapped at a position between 41 and 41.5 min on the E. coli chromosome, in the vicinity of the ruv operon.

Bacterial Proteins↗
PubMed1993

[Auditory lateralization in monozygotic twins: a study with dichotic consonant-vowel recall].

Auditory lateralization was examined in 21 monozygotic twin pairs (n = 42) and 52 singletons (healthy volunteers). Nine of the twin pairs were discordant for handedness, and 12 consisted of concordantly right-handed persons. All subjects were studied with a German dichotic consonant-vowel recall test using the syllables /ka/, /ta/, /pa/, /ga/, /da/ and /ba/ as stimuli. There was (i) a marked right-ear advantage in right handed singletons (as expected), (ii) no significant ear advantage among monozygotic twins (neither among those concordant nor those discordant handedness), and (iii) no relation between the direction of ear advantage within twin pairs. These data suggest that auditory lateralization is largely determined nongenetically.

Adult↗
PubMed1992

Inhibition of cell proliferation in Saccharomyces cerevisiae by expression of human NAD+ ADP-ribosyltransferase requires the DNA binding domain ("zinc fingers").

Constitutive expression of human nuclear NAD+: protein ADP-ribosyltransferase (polymerizing) [pADPRT; poly(ADP-ribose)polymerase; EC 2.4.2.30] as an active enzyme in Saccharomyces cerevisiae, under the control of the alcohol dehydrogenase promoter, was only possible with simultaneous inhibition of ADP-ribosylation by 3-methoxybenzamide. Induction of fully active pADPRT from the inducible galactose epimerase promoter resulted in inhibition of cell division and morphological changes reminiscent of cell cycle mutants. Expression of a pADPRT cDNA truncated at its 5' end had no influence on cell proliferation at all. Obviously the amino-terminal part of the DNA binding domain containing the first "zinc finger", which is essential for inducibility of pADPRT activity by DNA breaks, is also required for inhibition of cell growth on expression in yeast. Full-length as well as truncated pADPRT molecules were directed to the cell nucleus where the fully active enzyme produced large amounts of poly(ADP-ribose) by automodification. Since pADPRT turned out to be the only target for ADP-ribosylation in these cells, elevated levels of poly(ADP-ribose) were the most likely cause of inhibition of cell division, presumably resulting from interaction with chromosomal proteins.

Adenosine Diphosphate Ribose↗
PubMed1992

Is trichomoniasis often associated with bacterial vaginosis in pregnant adolescents?

The same criteria for identifying bacterial vaginosis are often present in women with trichomoniasis. These criteria include elevated vaginal pH, vaginal odor, homogeneous discharge, increased anaerobic bacteriologic vaginal flora, and elevated levels of bacterial enzymes. Clinically mixed vaginal infections occur, and because the treatment for these two conditions can be different, it is important to distinguish between them. Trichomoniasis can interfere with a Gram stain diagnosis or the proline aminopeptidase test for bacterial vaginosis. Clue cells are not generally found in women with Trichomonas vaginalis, but when present, they strongly indicate the concomitant presence of bacterial vaginosis.

Adolescent↗
PubMed1992

Stabilization of Streptomyces lividans by homologous recombinational insertion.

We have developed a system for the introduction and maintenance of novel tandem repeats in the chromosome of Streptomyces lividans 66. This was achieved by introducing, via transformation, Escherichia coli "suicide" vectors carrying manipulated S. lividans DNA fragments. Selection for antibiotic resistance markers carried on such plasmids permitted the isolation and maintenance of mutant strains containing novel tandem repeats formed by the integration into the chromosome of the plasmids, via homologous recombination between plasmid-borne chromosomal sequences and identical sequences on the chromosome. When novel repeats were introduced, and maintained, in regions of the chromosome which become deleted in unstable strains of S. lividans, those deletion events were blocked. Surprisingly, such strains were also 10 to 20-fold more stable than the parent even in the absence of selection. In stable regions of the chromosome, the maintenance of novel repeats had no obvious effect on the deletion events. This strategy could be generally applicable to industrial strains of Streptomyces, where instability is a common problem.

Chromosome Deletion↗
PubMed1992

Pectin decomposition and associated nitrogen fixation by mixed cultures of Azospirillum and Bacillus species.

Cocultures of different Azospirillum species with Bacillus polymyxa or Bacillus subtilis allow the efficient utilization of pectin as carbon and energy sources for nitrogen fixation. The nitrogenase activity obtained with cocultures was as high as 30-80 nmol C2H4 h-1 mL-1, a much higher value than that obtained with pure cultures of either Azospirillum (up to 13 nmol C2H4 h-1 mL-1) or B. polymyxa (up to 2 nmol C2H4 h-1 mL-1) alone. To establish to what extent each partner contributed to nitrogenase activity, acetylene reduction was assayed as a function of time and it was also measured on Azospirillum cultivated in the cultures filtrates of the Bacillus. The results suggested that the nitrogenase activity was mostly produced by Azospirillum. The nitrogenase activity occurred at the expense of the degradation and fermentation products of the pectin. The new pectinolytic species, Azospirillum irakense, utilized both degradation and fermentation products of pectin, whereas the nonpectinolytic strains (Azospirillum brasilense, Azospirillum lipoferum, Azospirillum amazonense) utilized only the fermentation products of pectin, including acetic and succinic acids. These cocultures can be considered as metabolic associations, where the Bacillus produces degradation and fermentation products of pectin, which can be used by Azospirillum species.

Azospirillum↗
PubMed1991

Cytogenetic and molecular characterization of a newly established neuroblastoma cell line LS.

A new human neuroblastoma cell line (LS) that originated from an abdominal tumor of a 16-month-old girl is presented; it was classified, according to Evans, as being stage III. Morphological (dense-core particles) and biochemical characteristics (dopamine-beta-hydroxylase, acetylcholinesterase, neuron-specific-enolase) confirmed the diagnosis. In addition to a slightly variable modal chromosome number of 48 or 49 (because of marker-chromosomes and autosomal trisomies), cytogenetic analysis revealed two constantly appearing chromosomes with homogeneously stained regions (HSR's). The karyotype remained constant over 50 passages in vitro [49,XX, -12, +der5, + 17, + mar1, + mar2]. Double minutes were a rare phenomenon and appeared only in a few metaphases. In situ hybridization showed that some of the HSR's consisted of amplified N-myc copies. The distribution of the N-myc copies according to in situ hybridization signals along the HSR's was compared with the data of Southern and Northern blotting analyses.

Abdominal Neoplasms↗
PubMed1990

Meningiomas of the lateral skull base: neurotologic manifestations and patterns of recurrence.

The eradication of basicranial meningiomas by traditional surgical techniques is often hindered by neoplastic entanglement with critical neurovascular structures. Apparent, complete tumor resection is frequently followed by extensive, yet clinically silent, recurrent disease with local infiltration of bone, cranial nerves, and brain. Fifty-five cases of sphenoid wing or parasellar meningioma were analyzed to identify clinical manifestations suggestive of early tumor recurrence. Regrowth patterns were then defined according to preoperative radiographic and intraoperative surgical findings. Medial tumor regrowth, involving the cavernous sinus, caused neurapraxia of cranial nerves III, IV, or VI, with associated diplopia or ophthalmoplegia. Inferior (caudal) regrowth of disease involved the infratemporal fossa, pterygomaxillary space, or paranasal sinuses by bony erosion of the middle cranial fossa floor or through natural anatomic foramina and fissures. Such inferior extension was manifested clinically by facial hypesthesia, trismus, and referred otalgia caused by trigeminal nerve involvement and by autophony or serous otitis media related to eustachian tube obstruction. Posterior tumor regrowth occurred along the petrous bone and horizontal carotid canal, resulting in internal auditory meatus erosion and cerebellopontine angle extension with associated tinnitus, hearing loss, unsteadiness, and occasional facial twitching. While the clinical and radiographic evaluations of any patient with a suspected recurrent basicranial meningioma are critical in planning the method and magnitude of reoperation, an understanding of potential recurrence patterns can be used in devising more extensive, combined approaches that may allow complete tumor extirpation at the initial surgical intervention.

Adult↗
PubMed1990

Differential patterns of memory loss in patients with Alzheimer's disease and Korsakoff's disease.

Patients with Korsakoff's disease or the likely diagnosis of Alzheimer's dementia were tested on various mnemonic tasks and the results compared to the performance of alcoholic or normal controls. The experimental outcome indicates similar perceptual learning processes of Alzheimer and Korsakoff subjects. On the other hand, both groups of patients showed a somewhat different pattern of episodic memory loss, and a different proportion of intrusion and omission errors in the learning of semantically related words. The results are discussed with respect to some neuropathological and neuropsychological sequelae.

Alcohol Amnestic Disorder↗
PubMed1990

[Computerized tomography findings in hormonally inactive adrenal gland tumors].

CT examinations of 6 years served as basis for the incidence of hormonally inactive space-occupying masses at the adrenal. Of a total of 25,000 patients, 313 (1.3%) suffered from disease of the adrenals, and of these 261 patients had a hormonally inactive adrenal tumour. Adenomas were the most frequent space-occupying growths (101 patients), followed by metastases of the adrenals (77 patients), whereas adrenal carcinomas (4 patients), myelolipomas (3 patients), ganglioneuromas (3 patients) adrenal cysts (3 patients) and adrenal haemorrhages (2 patients) were rare findings.

Adenoma↗
PubMed1989

Physiological effects of a mouth-borne heat exchanger during heavy exercise in a cold environment.

A mouth-borne heat and moisture exchanger (HME) was tested. Nine healthy subjects performed an incremental-load cycle ergometry test to exhaustion, breathing once through the HME and once through a similar device without heat-exchange function (control). HME substantially increased inspired gas temperatures and decreased expired gas temperatures measured at the mouth; at 260 W (pulmonary ventilation (VE) approximately 1001 min-1) these changes amounted to + 15 degrees C and -5 degrees C, respectively. The breathing resistance was increased by HME but remained well within tolerable levels even during severe exercise. This was reflected in the subjective assessments of breathing resistance and breathing discomfort which, at any given workload, were rated similarly in the HME and control conditions. Also, time to exhaustion as well as oxygen uptake and VE at a given workload were unaffected by HME. That even at high pulmonary ventilations HME provided a good heat-exchange function while keeping breathing resistance relatively low suggests HME to be a useful aid for individuals suffering from cold-induced bronchospasm.

Adult↗