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Biomedical subjects

C Kaiser

Publications and source records attributed to C Kaiser.

At least 37 records · Page 2Linked to original sources
PubMed1999

Functional genomics in cancer research: identification of target genes of the Epstein-Barr virus nuclear antigen 2 by subtractive cDNA cloning and high-throughput differential screening using high-density agarose gels.

In the past, the identification and isolation of phenotype-associated genes was a difficult and time-consuming task. However, recent improvements of methods that are designed to isolate differentially expressed genes have remarkably speeded up the process of target gene isolation. The ultimate goal of functional genomics is to apply these technologies to clone phenotype-associated genes irrespective of the availability of probes (e.g., antibodies) and an intimate knowledge of biological background. We demonstrate the use of a novel subtractive cDNA cloning approach for the isolation and characterization of target genes of the Epstein-Barr virus nuclear antigen 2 (EBNA2). Two different subtractive cDNA libraries specific for two different time periods following activation of a conditional estrogen receptor/EBNA2 (ER/EBNA2) fusion protein were generated. Comparison of the two libraries by cross-hybridization experiments allowed the differentiation between direct and indirect target genes of EBNA2 and led to the identification of a novel direct target gene of EBNA2.

Cloning, Molecular↗
PubMed1999

Effects of EDTA-induced hypocalcaemia and stress on plasma TNF-alpha, IL-1-ra, G-CSF, GM-CSF and S-100 in dairy cows.

The pathophysiology of postparturient paresis is still not completely understood. Knowledge recently acquired in immunology, endocrinology and cell physiology has still to be integrated in order to elucidate the aetiopathogenesis of the disease. For that purpose, the effect of the EDTA infusion model on the plasma concentrations of selected cytokines and growth factors, and of a calcium binding protein was examined in dairy cows. Six 6- to 11-year-old Brown Swiss cows in mid lactation were infused with a 5% solution of Na2EDTA in one jugular vein over a period of 5 h. Blood samples were collected from the contralateral side daily two days before, and then hourly for five hours during the infusion, hourly for five hours after the end of the infusion, and once daily for 10 days thereafter. The plasma concentrations of cortisol, tumour necrosis factor-alpha, interleukin-1 receptor antagonist, granulocyte colony-stimulating factor, granulocyte and macrophage colony-stimulating factor, and the calcium binding protein S-100 were determined. Before the EDTA infusion, during the infusion and for two days thereafter, the mean plasma concentrations of cortisol were significantly higher than those from days 4 to 10 after the infusion. The plasma concentrations of tumour necrosis factor-alpha and interleukin-1 receptor antagonist followed a similar profile. At the end of EDTA infusion, low concentrations of granulocyte colony-stimulating factor were detected in one cow only. On days 3 and 4, the mean plasma concentrations of granulocyte colony-stimulating factor were significantly higher than the pre-infusion values, but this was followed by a significant decrease on post-infusion day 5. From day 4 to 7, the plasma concentrations of S-100 were significantly lower than the pre-infusion values. The importance of these findings in the pathophysiology of postparturient paresis remains to be established.

Animals↗
PubMed1999

Mutational analysis of the cbb operon (CO2 assimilation) promoter of Ralstonia eutropha.

PL promoters direct the transcription of the duplicated cbb operons from the facultative chemoautotroph Ralstonia eutropha H16. The operons encode most enzymes of the Calvin-Benson-Bassham carbon reduction cycle required for CO2 assimilation. Their transcription depends on the activator protein CbbR. Structure-function relationships in the cloned chromosomal promoter region were analyzed by site-directed mutagenesis. PL was altered in its presumed hexameric -35 and/or -10 box or in the spacer region between the boxes to achieve a greater or lesser resemblance to the structure of the sigma70 consensus promoter of Escherichia coli. PL::lacZ transcriptional fusions of various promoter variants were assayed in transconjugant strains of R. eutropha as well as in corresponding cbbR deletion mutants. Mutations increasing the similarity of the -35 and/or -10 box to the consensus sequence stimulated PL activity to various extents, whereas mutations deviating from the consensus decreased the activity. The length of the spacer region also proved to be critical. The conversion of the boxes, either individually or simultaneously, into the consensus sequences resulted in a highly active PL. All improved PL mutants, however, retained the activation under inducing or derepressing growth conditions, although the full-consensus promoter was nearly constitutive. They were also activated in the cbbR mutants. The activity of the overlapping, divergently oriented cbbR promoter was less affected by the mutations. The half- and full-consensus PL mutants were comparably active in E. coli. Two major conclusions were drawn from the results: (i) the location and function of PL were verified, and (ii) indirect evidence was obtained for the involvement of another regulator(s), besides CbbR, in the transcriptional control of the R. eutropha cbb operons.

Bacterial Proteins↗
PubMed1999

The proto-oncogene c-myc is a direct target gene of Epstein-Barr virus nuclear antigen 2.

Epstein-Barr virus (EBV) infects and transforms primary B lymphocytes in vitro. Viral infection initiates the cell cycle entry of the resting B lymphocytes. The maintenance of proliferation in the infected cells is strictly dependent on functional EBNA2. We have recently developed a conditional immortalization system for EBV by rendering the function of EBNA2, and thus proliferation of the immortalized cells, dependent on estrogen. This cellular system was used to identify early events preceding induction of proliferation. We show that LMP1 and c-myc are directly activated by EBNA2, indicating that all cellular factors essential for induction of these genes by EBNA2 are present in the resting cells. In contrast, induction of the cell cycle regulators cyclin D2 and cdk4 are secondary events, which require de novo protein synthesis.

Cell Line, Transformed↗
PubMed1999

Identification of the putative mammalian orthologue of Sec31P, a component of the COPII coat.

The regulation of intracellular vesicular trafficking is mediated by specific families of proteins that are involved in vesicular budding, translocation, and fusion with target membranes. We purified a vesicle-associated protein from hepatic microsomes using sequential column chromatography and partially sequenced it. Oliogonucleotides based on these sequences were used to clone the protein from a rat liver cDNA library. The clone encoded a novel protein with a predicted mass of 137 kDa (p137). The protein had an N terminus WD repeat motif with significant homology to Sec31p, a member of the yeast COPII coat that complexes with Sec13p. We found that p137 interacted with mammalian Sec13p using several approaches: co-elution through sequential column chromatography, co-immunoprecipitation from intact cells, and yeast two-hybrid analysis. Morphologically, the p137 protein was localized to small punctate structures in the cytoplasm of multiple cultured cell lines. When Sec13p was transfected into these cells, it demonstrated considerable overlap with p137. This overlap was maintained through several pharmacological manipulations. The p137 compartment also demonstrated partial overlap with ts045-VSVG protein when infected cells were incubated at 15 degrees C. These findings suggest that p137 is the mammalian orthologue of Sec31p.

Amino Acid Sequence↗
PubMed1998

Exposure of in vitro-produced bovine embryos to foot-and-mouth disease virus.

The aim of this study was to investigate whether foot and mouth disease virus (FMDV) interacts with in vitro produced (IVP) bovine embryos. One milliliter of a suspension of FMDV (2 x 10(7) TCID50/mL) was added to several batches of these embryos 7 d after in vitro fertilization, by which time they had either developed to the morula/blastocyst stage (n = 256) or degenerated (n = 260). Six experiments were performed in which developed or degenerated batches of embryos were incubated with FMDV for periods of 1 h (3), 2 h (2) or 4h (1). After this, the embryos were washed 10 times according to the International Embryo Transfer Society (IETS), then pooled and ground up to form a suspension, and assayed on cell cultures for FMDV. The cell cultures were observed daily for cytopathic effects for 3 d post exposure. In addition to the cell culture method, the polymerase chain reaction (PCR) technique was used to assay for the presence of the virus in the washing fluids. Assays for FMDV were also conducted on the first and second wash and on the pooled sample constituting the eight, ninth and tenth wash. With the exception of the second wash from a batch of embryos exposed to FMDV for 2 h, all samples of the first and second wash produced FMDV cytopathic effects, but none occurred with the pooled samples of the 8th, 9th and 10th wash. FMDV was also isolated from all but 1 of the batches of embryos after 1 h of incubation, from 1 of 4 batches after 2 h of incubation and from all batches after 4 h incubation. By contrast, the presence of virus could not be demonstrated by PCR based on the technique used here. These results show that 7 d old IVP bovine embryos can retain FMDV after washing, unlike in vivo-derived embryos, which do not appear to carry risks of FMDV transmission when washed according to IETS recommendations. Stricter controls are, therefore, necessary when using IVP embryos from cattle in a non-FMD-free zone in domestic or international trade.

Animals↗
PubMed1998

Regulation of Raf-1 kinase by TNF via its second messenger ceramide and cross-talk with mitogenic signalling.

Raf-1 kinase is a central regulator of mitogenic signal pathways, whereas its general role in signal transduction of tumour necrosis factor (TNF) is less well defined. We have investigated mechanisms of Raf-1 regulation by TNF and its messenger ceramide in cell-free assays, insect and mammalian cell lines. In vitro, ceramide specifically bound to the purified catalytic domain and enhanced association with activated Ras proteins, but did not affect the kinase activity of Raf-1. Cell-permeable ceramides induced a marked increase of Ras-Raf-1 complexes in cells co-expressing Raf-1 and activated Ras. Likewise, a fast elevation of the endogeneous ceramide level, induced by TNF treatment of human Kym-1 rhabdomyosarcoma cells, was followed by stimulation of Ras-Raf-1 association without significant Raf-1 kinase activation. Failure of TNF or ceramide to induce Raf-1 kinase was observed in several TNF-responsive cell lines. Both TNF and exogeneous C6-ceramide interfered with the mitogenic activation of Raf-1 and ERK by epidermal growth factor and down-regulated v-Src-induced Raf-1 kinase activity. TNF also induced the translocation of Raf-1 from the cytosolic to the particulate fraction, indicating that this negative regulatory cross-talk occurs at the cell membrane. Interference with mitogenic signals at the level of Raf-1 could be an important initial step in TNF's cytostatic action.

3T3 Cells↗
PubMed1998

High incidence of epilepsy related to onchocerciasis in West Uganda.

The incidence of epilepsy was assessed in an onchocerciasis endemic area in West Uganda over a period of 4 years. A high overall crude incidence rate of 215 per 100000 person-years was found (age-adjusted: 156 per 100000 person-years) and the incidence in zones of high onchocerciasis endemicity was significantly higher than in low endemic zones (age adjusted rates: 232 per 100000 person-years versus 77 per 100000 person-years; Yates corrected chi2: P < 0.01). The data constitute a baseline for an ongoing intervention study on the effects of onchocerciasis control on epilepsy incidence in the study area. If a causal relationship between onchocerciasis and epilepsy can be confirmed, this would have significant implications for the concept of morbidity due to onchocerciasis and for the prevention of epilepsy in the endemic areas.

Adolescent↗
PubMed1998

Ultrasonography in suspected acute appendicitis in childhood-report of 1285 cases.

OBJECTIVE: For the assessment of the diagnostic value of real-time ultrasonography (US) in children with suspected acute appendicitis (a.A.) the results of graded compression US are compared with clinical and histological final diagnoses. METHODS: In a prospective study over nearly 9 years we examined 1285 children aged 1-15 years (m=514, f=771). Using a 5-MHz curved array transducer the right lower quadrant was examined in a graded compression technique. RESULTS: Prevalence of histologically proven a.A. was remarkably low (9%). In diagnosis of acute appendicitis in childhood US achieves a sensitivity of 92%, specificity of 98%, a positive predictive value of 90% and a negative predictive value of 98%. The overall accuracy was 98%. Mesenteric lymphadenitis was seen in 181 cases (prevalence 12%) and terminal ileitis occasionally accompanied by mesenteric lymphadenitis was seen in 116 cases (prevalence 9%). CONCLUSION: In children with suspected appendicitis US of the abdomen gives great diagnostical value for differential diagnosis of a.A. and other more frequent inflammatory diseases of the ileocoecal region. Thus US provides further reliable information to the referring physician. Consequently it is necessary to perform US in each child with acute abdominal pain, even if clinical diagnosis seems to be well established.

Acute Disease↗
PubMed1998

Transport from the endoplasmic reticulum to the Golgi.

Two crucial aspects of transport vesicle function have recently been reconstituted using purified proteins and chemically defined lipid bilayers. The reconstituted steps are the assembly of a polymeric protein coat on the cytosolic surface of the membrane, and bilayer fusion based on the pairing of proteins in the vesicle and target membrane. These advances now set the stage to address major unresolved questions of how vesicle budding and vesicle fusion are regulated, how specific cargo molecules are incorporated into vesicles, and how vesicles find their target membrane.

Animals↗
PubMed1998

Antiepileptic drug treatment in rural Africa: involving the community.

The vast majority of patients with epilepsy in developing countries do not receive adequate medical treatment and an estimated percentage of 80-90% are without any treatment. Poor infrastructure, insufficient availability of drugs and scarcity of trained medical personnel are relevant factors for this situation. Traditional concepts about epilepsy may also affect acceptance and compliance to modern treatment. We report our experience with anti-epileptic drug (AED) treatment in a rural African community with a high prevalence of epilepsy. After identification of the patients during a prevalence survey on epilepsy, the input of the medical service of the district to the treatment scheme was reduced to a 6-monthly medical visit to the area and long-term provision of AED to the patients. Members of the community were integrated as assistants in the distribution of the drugs and community participation was gradually enhanced over the first year of the programme. A cost-sharing system for the financing of the community assistants was introduced and a self-help committee of epilepsy patients and their families was founded. Within the first 20 months the patients showed good compliance as indicated by a growing number of patients presenting for treatment and a low rate of discontinuation of the treatment. A marked improvement could be observed for most of the patients treated with phenobarbitone in terms of reduction of seizure frequency although complete seizure control was achieved in only a few.

Africa↗
PubMed1996

Structure and function in rhodopsin: expression of functional mammalian opsin in Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae has been investigated for expression of mammalian opsin as an alternative to the currently used expression in COS-1 mammalian cells. The synthetic opsin gene was placed under the control of the inducible promoter GAL1 in the multicopy yeast/ Escherichia coli shuttle vector YEpRF1. Transformation of a GAL+ S. cerevisiae strain with the vector and growth of galactose-induced cultures to saturation showed the production of 2.0 +/- 0.5 mg of opsin from about 10(10) cells by ELISA. The addition of 11-cis-retinal to either cell spheroplasts or lysed cells showed that a fraction (2-4%) of the total expressed opsin reconstituted to rhodopsin. This fraction was purified to homogeneity and was shown to be fully functional and indistinguishable from bovine rhodopsin by the following criteria: (i) UV-visible absorption spectra, (ii) the formation of metarhodopsin II and its rate of decay, and (iii) initial rate of transducin activation as measured by the formation of a complex between transducin (alpha subunit) and guanosine 5'-[gamma-[35S]thio]triphosphate. The purified fraction was homogeneously glycosylated. However, glycosylation was distinct from that of bovine rhodopsin as judged by mobility on SDS/PAGE and endoglycosidase H sensitivity.

Animals↗
PubMed1996

Recognizing Ullrich-Turner syndrome by discriminant analysis of craniofacial structure.

In the present paper, we propose an efficient strategy for identification of craniofacial anomalies in the Ullrich-Turner syndrome (UTS). Standardized portrait- and profile-photographs were taken of 21 UTS patients with X-monosomy and 21 normal females. Twenty-seven craniofacial parameters were read from the photographs. The data were analyzed by discriminant analysis, a multivariate statistical method. The result was a function represented by a linear combination of all those craniofacial parameters which best separate the two groups. The discriminant function was applied to 15 additional patients with UTS of various cytogenetic types. All 15 patients were classified correctly. The technique facilitates syndrome-recognition and is a contribution toward the study of karyotype-phenotype relations.

Adolescent↗
PubMed1996

-Case report of clinical and pathophysiological similarities of Moschkowitz disease and HELLP syndrome-.

This case report describes for the first time a manifestation of thrombotic thrombocytopenic purpura (TTP, Moschcowitz's disease) during pregnancy. The characteristic neurologic symptoms of TTP were missing, while the typical clinical signs of the HELLP syndrome could be observed. Furthermore the biochemical proof of TTP was obtained by tracing ultra-large clotting factor VIII (von Willebrand factor) multimers in the patient's plasma. Thus the assumption is supported that TTP and HELLP syndrome are diseases of one pathophysiological entity with different symptomatologies. Because of the frequent relapse of TTP, differentiation between TTP and HELLP syndrome is of great clinical importance, independent of future pregnancies.

Adult↗
PubMed1996

The prevalence of epilepsy follows the distribution of onchocerciasis in a west Ugandan focus.

Epidemiological surveys indicate that the prevalence of epilepsy is higher in developing countries than in industrialized countries. Except for neurocystocercosis due to Taenia solium, little is known about possible underlying causes. This article reports the relationship between epilepsy and onchocerciasis in an Onchocerca volvulus endemic area in West Uganda. Individuals complaining of seizures were identified by means of a population census in 12 villages. Active epilepsy was confirmed in 61 of 4743 inhabitants (crude prevalence rate = 1.3%; age-standardized rate = 1.1%). Distribution of epilepsy in the study area was clustered, ranging from a prevalence of 0.2% to 3.4% in different villages. Age-specific prevalence was highest between 10 and 19 years, with a rate of 3.6% for the study are as a whole, and up to 10.0% in villages of high epilepsy prevalence. The prevalence of onchocerciasis in the 10-19-year-old age group was assessed by skin-snip biopsy and ranged from 15% to 85% in different villages. Epilepsy was significantly more frequent in the three villages with the highest levels of O. volvulus endemicity than in other villages (P < 0.0001). Serological testing for T. solium infection was positive in one and borderline in three of 53 epilepsy patients tested. The significant correlation between epilepsy and onchocerciasis did not change when these four patients were excluded from the analysis. These findings suggest a strong association between epilepsy and onchocerciasis in this area. This could have significant implications for the concept of morbidity due to O. volvulus.

Adolescent↗
PubMed1994

Isolation of two H1N2 influenza viruses from swine in France.

Samples collected in 1987 and 1988 in Brittany from influenza-infected swine made it possible to isolate and antigenically characterize two H1N2 recombinant viruses (Sw/France/5027/87 and Sw/France/5550/88). The former virus was cloned and reinoculated to swine to allow reproduction of the disease and reisolation of a strain similar to the original one. The serodiagnostic tests carried out on both the original sera and those from the experimentally infected animals confirmed that the virus was actually type Sw/H1N2.

Animals↗