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Biomedical subjects

M A Kern

Publications and source records attributed to M A Kern.

16 recordsLinked to original sources
PubMed2006

[Primary infection with Epstein-Barr virus in a 77-year-old patient with B symptoms and hepatitis -- a case report].

Epstein-Barr virus (EBV) infection has a prevalence of 90 % and is - depending on the immune status of the host - associated with a broad spectrum of clinical manifestations. By presenting a case report we would like to demonstrate an unusual clinical course of a primary infection with EBV in an elderly patient. A 77-year-old patient was admitted to hospital in reduced health condition because of a persisting bronchopulmonary infection with B symptoms. The patient had already been treated with antibiotics. Because of elevated liver enzymes, a liver biopsy was performed. Histopathology revealed moderate acute hepatitis with cholangitis und endothelialitis, pointing to an EBV-induced hepatitis. Serological examinations confirmed the diagnosis, revealing a primary infection with positive EBV VCA IgM and IgG. EBV PCR of the liver tissue was positive, viral genome could be demonstrated within lymphocytes. A short period later the patient was discharged to reconvalescence. This case report demonstrates an unusual primary infection with EBV at the age of 77 with atypical clinical symptoms and hepatitis. The relevance of EBV in the differential diagnosis of atypical infectious diseases with hepatitis of unknown aetiology is strengthened on taking data reports from the literature into consideration.

Aged↗
PubMed2006

Induction of early murine cytomegalovirus infection by different reporter gene-associated recombinant viruses.

Murine cytomegalovirus (MCMV) has provided useful models for acute, chronic and latent CMV infection because of its similarities in structure and biology with human CMV. We report the induction of acute MCMV hepatitis with different bacterial artificial chromosome (BAC)-cloned virus constructs [MCMV-SEAP which includes the gene for secreted alkaline phosphatase (SEAP) under Rous sarcoma virus (RSV)-promoter control, MCMV-GFP which includes the gene for enhanced green fluorescent protein (eGFP) under HCMV-ie promoter control, MCMV-HBs includes the gene for hepatitis B surface antigen (HBsAg) under simian virus (SV)40-promoter control and the DeltaMC95.21 virus in which the m152 gene was deleted and substituted by the reporter gene lacZ] in order to elucidate the histopathological changes together with different reporter-gene products in the liver tissue and the effect of the deletion of a certain gene. All the virus constructs induced a similar mild acute hepatitis which had its climax from days 3 to 5 post-infection in immunocompetent mice. In situ, the reporter-gene products beta-galactosidase and secreted alkaline phosphatase could be visualized in relation to the inflammatory changes. The composition of the invading cell populations did not change even in the absence of the m152 gene. Additionally discrete inflammatory changes were seen in kidney and serosa while the other organs were not involved. This model helps us understand the immunological and histopathological mechanisms of the CMV-induced hepatitis, which plays an important role especially in the immunocompromised patient. The morphological changes can be analysed while the respective reporter gene product is expressed by the virus construct.

Acute Disease↗
PubMed2005

[Clear cell tumor of the lung].

Clear cell tumors of the lung are rare tumors composed of epithelioid HMB45 positive tumor cells. It has been proposed that clear cell tumors generate from perivascular epithelioid cells which are also found in renal angiomyolipoma. Due to its morphologic epithelioid features with clear cytoplasm the distinction from either primary or metastatic clear cell carcinoma is difficult. Usually clinical investigations do not lead to the final diagnosis so that only subsequent histological examination and immunophenotyping can establish the correct tumor classification. We describe the case of a 52 year old woman who underwent exploratory thoracotomy because of a lung mass in the right lower lobe. In frozen sections a solid trabecular tumor was diagnosed, paraffin histology and immunohistochemistry revealed a clear cell tumor of the lung. The difficulty of the correct diagnosis of the clear cell tumor of the lung in frozen sections is discussed as well as the differential diagnosis.

Adenocarcinoma, Clear Cell↗
PubMed2005

[Report of a spindle cell myoepithelialioma of the minor salivary glands with extensive lipomatous component].

Myoepitheliomas of the salivary glands are rare benign tumors composed of spindle-shaped myoepithelial cells, but may show plasmacytoid, epitheloid and clear cell-types that principally exhibit myoepithelial but not ductal differentiation. These tumors are mainly located in the major salivary glands and have sometimes abundant, acellular, mucoid or hyaline stroma but lack chondroid and myxochondroid foci, probably representing the one end of the spectrum of pleomorphic adenoma. Lipomatosis in the form of isolated small islands or scattered single lipocytes, is quite uncommon, and a large amount of adipose tissue in a pleomorphic adenoma and myoepithelioma is a rarity and only described in major salivary glands. We present the case report of a 38-year old man with a myoepithelioma of the minor palatinal salivary glands with extensive lipomatosis as an example of this rare phenomena.

Adipose Tissue↗
PubMed2005

Stage-extension device for transmission light microscopes.

For routine applications, more and more professional microscope users have removed the slide holders from their transmission light microscopes and frequently look over their histological specimens by moving them manually on the microscope stage. This method allows the operator to scan the specimen quickly under survey magnification and thus helps to save time. However, when using detail magnification, moving the sample by hand is simply not precise enough. This drawback becomes particularly evident with photo-documentations or video demonstrations. Here I describe an innovative stage-extension device that allows quick movement of the slide by hand as well as precise positioning of the specimen by using the micrometre fine adjustment of the coaxial stage-drive mechanism.

Journal Article↗
PubMed2001

Amyotrophic lateral sclerosis: evidence for intact hepatocyte growth factor/met signalling axis.

Hepatocyte growth factor (HGF) is a secreted cytokine which is expressed in the central nervous system (CNS) together with its specific receptor MET. Since HGF exerts strong neurotrophic activity including motoneurons, we have further analysed whether the HGF/MET axis is defective in patients with amyotrophic lateral sclerosis (ALS). Intrathecal HGF-secretion was measured in cerebrospinal fluid (CSF) from patients with amyotrophic lateral sclerosis and in controls without neurological diseases using a specific sandwich immunoassay (ELISA). MET-expression was analysed by immunohistology in spinal cord cross-sections of ALS patients and unaffected controls. The HGF concentrations in CSF were moderately but significantly increased in ALS patients compared to healthy controls (580 pg/ml vs 348 pg/ml). MET-protein was detectable in spinal cord motoneurons of patients with ALS as well as unaffected controls. The data demonstrate that ALS does not show a lack of the trophic signalling axis, HGF/MET, suggesting that the signalling system itself is not affected. The moderate increase in HGF-secretion may represent a compensatory effect.

Adult↗
PubMed2001

Drug-resistance in human melanoma.

Advanced malignant melanoma has a poor prognosis since chemotherapy is mostly ineffective due in part to the intrinsic and/or extrinsic resistance of melanoma cells to systemic treatment with anti-neoplastic agents. The reasons for the chemoresistant phenotype are unknown. The relevance of well-analyzed drug-resistance mechanisms, e.g., intracellular/extracellular transport and induction of certain enzyme systems, is reviewed. Most anti-cancer drugs kill susceptible cells through induction of apoptosis. Therefore, it appears that differences in the apoptotic pathways which lead to apoptotic deficiency may account for the ability of some tumor cells to resist drug therapy. Human melanomas, which are characteristically drug-resistant, are more likely to have altered apoptotic pathways and fewer pro-apoptotic molecules. Tumor cells with these characteristics are seldom sensitive to drugs. The complexity of the molecular variants involved in signal transduction along apoptotic pathways suggests that the cell may have a variety of possibilities for regulating apoptosis and generating apoptotic deficiency. Thus, apoptosis and apoptotic deficiency should be analyzed to better clarify the mechanisms of melanoma resistance.

Apoptosis↗
PubMed2001

Concentrations of hepatocyte growth factor in cerebrospinal fluid under normal and different pathological conditions.

Hepatocyte growth factor (HGF) and its specific receptor, MET, are expressed in the developing and adult mammalian brain. Recent studies have shown a neurotrophic activity of HGF in the nervous system. The present study focused on HGF concentrations in the cerebrospinal fluid (CSF) and serum in normal persons and in different central nervous system (CNS) diseases considering blood-CSF barrier (BCB) function. Concentrations of HGF were analyzed using an enzyme-linked immunosorbent assay (ELISA). HGF was present in normal human CSF (346+/-126 pg/ml) representing approximately half of the HGF serum concentrations. The CSF HGF levels were not significantly changed in chronic CNS disease and in aseptic meningitis (419+/-71 pg/ml), but significantly increased in patients with bacterial meningitis (6101+/- 5200 pg/ml). The HGF levels in CSF were not influenced by increased serum concentrations in patients with normal or mildly affected BCB function. The results show that HGF is present in normal CSF and does not appear to cross the CSF barrier significantly unless it is severely disrupted. So far, strong increases of HGF concentration in CSF are only present in acute bacterial meningitis.

Acute Disease↗
PubMed2000

Expression of c-Met in developing rat hippocampus: evidence for HGF as a neurotrophic factor for calbindin D-expressing neurons.

Hepatocyte growth factor-scatter factor (HGF) is expressed in different parts of the nervous system, and has been shown to exhibit neurotrophic activity. Here we show that c-Met, the receptor for HGF, is expressed in developing rat hippocampus, with the highest levels during the first postnatal weeks. To study the function of HGF, hippocampal neurons were prepared from embryonic rats and treated with different HGF concentrations. In these cultures, HGF increased the number of neurons expressing the 28-kDa calcium-binding protein (calbindin D) in a dose-dependent manner. The effect of HGF was larger than that observed with either brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3), and cotreatment of the cultures with HGF and the neurotrophins was additive with respect to calbindin D neurons. Besides affecting the number of neurons, HGF significantly increased the degree of sprouting of calbindin D-positive neurons, suggesting an influence on neuronal maturation. BDNF and NT-3 stimulated neurite outgrowth of calbindin D neurons to a much smaller degree. In contrast to calbindin D neurons, HGF did not significantly increase the number of neurons immunoreactive with the neurotransmitter gamma-aminobutyric acid (GABA) in the hippocampal cultures. Immunohistochemical studies showed that c-Met-, calbindin D- and HGF-immunoreactive cells are all present in the dentate gyrus and partly colocalize within neurons. These results show that HGF acts on calbindin D-containing hippocampal neurons and increases their neurite outgrowth, suggesting that HGF plays an important role for the maturation and function of these neurons in the hippocampus.

Animals↗
PubMed1999

Expression of DNA repair proteins hMSH2, hMSH6, hMLH1, O6-methylguanine-DNA methyltransferase and N-methylpurine-DNA glycosylase in melanoma cells with acquired drug resistance.

Malignant melanoma is well known for its primary unresponsiveness to chemotherapy. The mechanisms conferring this intrinsic resistance are unclear. In this study, we investigated the role of genes involved in DNA repair in a panel of human melanoma cell variants exhibiting low and high levels of resistance to 4 commonly used drugs in melanoma treatment, i.e., vindesine, etoposide, fotemustine and cisplatin. We show that in melanoma cells exhibiting resistance to cisplatin, etoposide and vindesine, the nuclear content of each of the DNA mismatch repair (MMR) proteins hMLH1, hMSH2 and hMSH6 was reduced by 30-70%. A decreased expression level of up to 80% of mRNAs encoding hMLH1 and hMSH2 was observed in drug-resistant melanoma cells selected for cisplatin, etoposide and fotemustine, while vindesine-selected cells showed only moderate reduction. In melanoma cells that acquired resistance to fotemustine, the amount of nuclear MMR proteins was nearly unaltered, whereas the activity of O6-methylguanine-DNA methyltransferase (MGMT) was considerably enhanced. Activity of N-methylpurine-DNA glycosylase (MPG) was not significantly altered in any of the drug-resistant melanoma cells. Our data indicate that modulation of both MMR components and MGMT expression level may contribute to the drug-resistant phenotype of melanoma cells.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Association of genomic imbalances with resistance to therapeutic drugs in human melanoma cell lines.

The reason why human malignant melanomas respond poorly to chemotherapy is not known. In an attempt to identify genes responsible for such resistance or sensitivity to therapeutic drugs, we studied the parental human melanoma cell line MeWo, as well as eight drug-resistant sublines of MeWo. These have low and high levels of resistance to four chemotherapeutic drugs with different modes of action: Vindesine, cisplatin, fotemustine and etoposide. Comparative genomic hybridizations with genomic DNA from these cell lines as probes revealed a number of chromosome gains and losses which occurred upon selective pressure during development of the sublines. The MeWo subline with high resistance to the topoisomerase II inhibitor, etoposide, exhibited the highest number of acquired chromosome imbalances. Interestingly, the two lines with high resistance to cisplatin and fotemustine, respectively, shared three additional imbalances, loss of 9p, loss of distal 12p and gain on distal 15q. The importance of these coincident imbalances is discussed.

Aneuploidy↗
PubMed1998

The Platelet Function Analyzer (PFA-100): a novel in-vitro system for evaluation of primary haemostasis in children.

The PFA-100 system provides an in-vitro method of assessing primary platelet-related haemostasis by measuring the time (the closure time, or CT) taken for a platelet plug to occlude a microscopic aperture cut into a membrane coated with collagen and either epinephrine or ADP. We used the system to establish normal ranges for CTs in healthy children, adults and neonates. Mean CTs of healthy children were independent of the needle gauge used (21G or 23CG) for blood sampling; they were very similar to the mean CTs of healthy adults, but longer than mean CTs of healthy neonates. Although children with haemophilia had normal CTs, the PFA-100 system was found to be potentially useful in screening for von Willebrand disease in children.

Adolescent↗
PubMed1996

Treatment of melanoma cells with the synthetic retinoid CD437 induces apoptosis via activation of AP-1 in vitro, and causes growth inhibition in xenografts in vivo.

Human malignant melanoma is notoriously resistant to pharmacological modulation. We describe here for the first time that the synthetic retinoid CD437 has a strong dose-dependent antiproliferative effect on human melanoma cells (IC50: 5 x 10(-6) M) via the induction of programmed cell death, as judged by analysis of cell morphology, electron microscopical features, and DNA fragmentation. Programmed cell death was preceded by a strong activation of the AP-1 complex in CD437-treated cells as demonstrated by gel retardation and chloramphenicol transferase (CAT) assays. Northern blot analysis showed a time-dependent increase in the expression of c-fos and c-jun encoding components of AP-1, whereas bcl-2 and p53 mRNA levels remained constant. CD437 also exhibited a strong growth inhibitory effect on MeWo melanoma cells in a xenograft model. In tissue sections of CD437-treated MeWo tumors from these animals, apoptotic melanoma cells and c-fos overexpressing cells were colocalized by TdT-mediated deoxyuridine triphosphate-digoxigenin nick end labeling (TUNEL) staining and in situ hybridization. Taken together, this report identifies CD437 as a retinoid that activates and upregulates the transcription factor AP-1, leading eventually to programmed cell death of exposed human melanoma cells in vitro and in vivo. Further studies are needed to evaluate whether synthetic retinoids such as CD437 represent a new class of retinoids, which may open up new ways to a more effective therapy of malignant melanoma.

Animals↗
PubMedDate not supplied

The effects of media viscosity on hemodynamics in selective arteriography.

Radiographic contrast media used for arteriography are generally more viscous than plasma or blood; however, little consideration is given to the hemodynamic effects of contrast media viscosity. In this study, in vivo and in vitro injection of isotonic solutions of saline and polyvinylpyrrolidone, having viscosities from 0.8 to 26 centipoise, have been made. The results demonstrate that, when the viscous saline reaches the microcirculation, the resistance to flow increases. The viscous saline thus significantly decreases flow immediately after the injection. At that time the pressure in the artery equals aortic pressure, but the local vascular resistance is elevated because of the viscous material present in the arterioles. Viscous contrast media would cause similar hemodynamic changes during and immediately following an injection. The effects of contrast media hypertonicity, however, modify the viscosity-related changes shortly after the contrast media reaches the capillaries.

Angiography↗
PubMedDate not supplied

Human melanoma cell lines selected in vitro displaying various levels of drug resistance against cisplatin, fotemustine, vindesine or etoposide: modulation of proto-oncogene expression.

Melanoma cells often display a multidrug-resistant phenotype, but the mechanisms involved are largely unknown. In order to establish a reproducable model system for studying the exact mechanisms conferring chemoresistance, we selected drug-resistant sublines in vitro derived from one parental human melanoma (MeWo) cell line. Four commonly used chemotherapeutic drugs (vindesine, etoposide, fotemustine, cisplatin) with different modes of action were choosen and stable sublines exhibiting four different levels of resistance against each drug were selected by continuous exposure over two years. Analysis of the drug-resistant sublines regarding their pharmacological characteristics and cross-resistance pattern revealed an up to 26-fold increased relative resistance against the alkylating agent fotemustine (MeWoFOTE) and an up to 35.7-fold increased relative resistance against topoisomerase-II-inhibiting etoposide (MeWoETO). Cisplatin selection (MeWoCIS) resulted in a 6-fold higher resistance compared to parental MeWo cells, whereas vindesine exposure (MeWoVIND) increased relative resistance up to 10.2-fold. Sublines selected separately for resistance to the DNA-damaging agents fotemustine, cisplatin and etoposide demonstrated strong cross-resistance. In comparison to the parental cell line drug-resistant sublines showed altered expression patterns of proto-oncogenes. Levels of p53 mRNA decreased with increasing resistance to vindesine, etoposide and fotemustine. Expression of bcl-2 family members (bax, bcl-x) was modulated by fotemustine, etoposide and cisplatin. In addition the expression of members of the fos (c-fos) and jun (c-jun, jun-D) gene family encoding transcription factors of the AP-1 complex was altered in all drug-resistant sublines. The pattern of expression varied with the inducing stimulus and this was paralleled by changes in the transactivation potential of AP-1. Our results reinforce the central role of AP-l in drug resistance probably through its participation in a programmed cellular stress response.

Antineoplastic Agents↗