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Biomedical subjects

M Kuhn

Publications and source records attributed to M Kuhn.

At least 145 records · Page 8Linked to original sources
PubMed1994

Identification of a promoter region for mxaF (moxF) from the type I methanotroph, Methylobacter albus BG8.

A fragment of Methylobacter albus BG8 DNA containing mxaF (moxF), the gene encoding the alpha subunit of methanol dehydrogenase, was previously cloned using a fragment of mxaF from Methylobacterium extorquens AM1 as a probe (Stephens et al., J. Bacteriol. (1988) 170, 2063-2069). In this study we identified the 5' portion of mxaF of M. albus BG8 and sequenced a 1.7-kb region containing the 5' portion of mxaF and 1.5 kb of upstream DNA. The deduced N-terminal amino acid sequence of mxaF was found to have very high similarity to the previously sequenced mxaF genes. The region directly upstream of mxaF was cloned into a promoter probe vector (pGD500), and promoter activity was demonstrated when the fragment was present in the correct orientation with relation to the reporter gene (lacZ). Using reverse transcriptase, the transcription initiation start site was determined, which was separated from the translation initiation site by 190 nucleotides.

Alcohol Oxidoreductases↗
PubMed1994

Enterochromaffin cells of the digestive system: cellular source of guanylin, a guanylate cyclase-activating peptide.

Guanylin, a bioactive peptide, has recently been isolated from the intestine; this peptide activates intestinal guanylate cyclase (i.e., guanylate cyclase C) and thus is potentially involved in the regulation of water/electrolyte transport in the gastrointestinal mucosa. As yet, the cells involved in synthesis, storage, or secretion of guanylin have not been identified by immunocytochemistry. We raised antisera against guanylin and investigated the entire gastrointestinal tract of guinea pigs by light and electron microscopical immunocytochemistry. Extracts of various intestinal segments and plasma analyzed on a Western blot revealed a peptide band corresponding to the molecular mass of guanylin. Localization studies in the entire digestive tract showed that guanylin is exclusively confined to enterochromaffin (EC) cells. Remarkably, most EC cells contacted the gut lumen by cell processes that were highly immunoreactive for guanylin. In addition to the well known secretion in an endocrine fashion, EC cells by circumstantial evidence may release guanylin into the gut lumen to activate guanylate cyclase C that is immediately located on the brush border of adjacent enterocytes. The unique localization of guanylin in EC cells may indicate that these cells are involved in the regulation of fluid secretion in the gastrointestinal mucous membrane.

Animals↗
PubMed1994

[Fatal outcome of pneumocystis-carinii pneumonia under low-dose methotrexate and prednisone therapy for chronic rheumatoid arthritis. Case report and literature review].

New therapeutic schemes have been proposed recently for treatment of rheumatoid arthritis. Among these, methotrexate at low doses is recommended as basic therapy, already shortly after the diagnosis is established. We report on a 68-year-old female with rheumatoid arthritis who developed bilateral pneumocystis-carinii pneumonia with a lethal course and bilateral sinusitis maxillaris with candida lusitaniae. Various opportunistic infections have been described in the literature after low-dose methotrexate. It is our view that the use of methotrexate in rheumatoid arthritis should still be considered cautiously until further data on the risk-benefit ratio of long-term use become available.

Aged↗
PubMed1994

Radioimmunoassay for circulating human guanylin.

A highly specific and sensitive radioimmunoassay for circulating human guanylin (guanylin-22-115) has been developed. Antibodies were raised against the amino-terminus (positions 4-16) of the peptide. Western blot analysis confirmed that the antibody selected for radioimmunoassay recognizes circulating high molecular weight (10.3 kDa) guanylin. Extraction and purification of guanylin from blood hemofiltrate and from blood plasma showed that circulating guanylin is detectable in corresponding amounts by the radioimmunoassay and by a specific bioassay. In 30 healthy subjects, the mean plasma concentration of immunoreactive (IR) guanylin was 42 +/- 3 fmol/ml. In 22 patients with chronic renal insufficiency, the concentrations of IR-guanylin were significantly enhanced (1,074 +/- 24 fmol/ml), indicating that kidneys metabolize and/or eliminate the circulating hormone.

Adult↗
PubMed1994

Emergency medicine.

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Adrenal Cortex Hormones↗
PubMed1994

Phosphatidylinositol-specific phospholipase C from Listeria monocytogenes contributes to intracellular survival and growth of Listeria innocua.

Listeria monocytogenes is a facultative intracellular organism that is capable of replicating within macrophage and macrophage-like cells. The species secretes a phosphatidylinositol-specific phospholipase C (PI-PLC) encoded by the plcA gene. A plcA gene from L. monocytogenes was cloned downstream of a gram-positive promoter in the plasmid pWS2-2. To determine what effect plcA would have on intracellular survival when introduced into Listeria innocua, a species that does not growth intracellularly or contain plcA, transformation with the recombinant pWS2-2 plasmid was performed. Phospholipase C activity in Listeria innocua/pWS2-2 was confirmed on a brain heart infusion-phosphatidylinositol agar plate, whereas wild-type L. innocua did not produce PI-PLC activity. Intracellular growth of L. innocua/pWS2-2 was subsequently measured in the macrophage-like cell line J774 by Giemsa staining and viable count determinations at specific time points following infection. The J774 cells infected with wild-type L. innocua showed a falling viable count through 8 h postinfection. Although J774 cells infected with L. innocua/pWS2-2 also initially displayed reduced viable counts, the viable count rose after 6 h postinfection and increased further at 8 h postinfection before a subsequent decline again at 16 h postinfection. Giemsa staining revealed fewer than 6 bacteria in individual macrophage cells at 2 h postinfection, and yet approximately 15% of the J774 cells had 6 to 12 bacteria localized to one area of the macrophage cell after 6 h; moreover, electron micrographs showed that the L. innocua/pWS2-2 cells were replicating inside the phagosome of the host cell. Furthermore, Thoria Sol labeling demonstrated that lysosomes had fused with these phagosomes, and acridine orange staining revealed that the compartments were acidified. These results demonstrate that L. innocua cells transformed with the plasmid-borne plcA gene, and expressing functional PI-PLC, are able to grow intracellularly in what appear to be phagolysosomes, although between 3 and 6 h is needed for this to manifest itself. Intracellular growth specifically in L. innocua may be a secondary function associated with the plcA gene product. The addition of this one gene, plcA, to a species of Listeria that in the wild-type state does not replicate intracellularly apparently can now allow some of the bacteria to transiently multiply inside the phagosomes of host macrophage cells.

Amino Acid Sequence↗
PubMed1994

Induction of cytokines in phagocytic mammalian cells infected with virulent and avirulent Listeria strains.

The present paper analyzes the cytokine response of mouse macrophages during infection by Listeria monocytogenes. The use of different mutants of L. monocytogenes impaired in various steps of the infection process allowed us to dissect the cytokine response. Cytokine mRNA expression was detected by PCR-assisted amplification of RNA extracted from macrophages after infection with different Listeria strains. An increase in the amount of mRNA for tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha), IL-1 beta, and IL-6 was detected in P388D1 macrophages infected with L. monocytogenes at 4 h postinfection. Interestingly, only hemolytic strains of L. monocytogenes were able to induce IL-1 alpha, IL-6, and TNF-alpha mRNA. This indicated that the induction of these cytokine mRNAs requires entry of the listeriae into the host cell cytoplasm. In contrast, IL-1 beta was also induced by infection with nonhemolytic mutants of L. monocytogenes which remain entrapped within the phagosome. The levels of TNF, IL-1 alpha, and IL-6 found in the supernatants of Listeria-infected P388D1 macrophages generally correlated well with the induction of the respective mRNAs, but it became obvious that cytokine activity is also regulated through posttranscriptional mechanisms. In vitro induction of the cytokines IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha was also observed by infection of bone-marrow-derived macrophages with L. monocytogenes.

Animals↗
PubMed1994

Listeria monocytogenes infection enhances transcription factor NF-kappa B in P388D1 macrophage-like cells.

In the present study, we investigated the effect of Listeria monocytogenes infection on the cellular level of the transcription factors NF-kappa B, AP-1, and NF-IL6 in the macrophage-like cell line P388D1 by using electrophoretic mobility shift assays. Infection with L. monocytogenes enhanced the formation of two NF-kappa B-like DNA-protein complexes, C1 and C2, whereas the concentration of AP-1 and NF-IL6 complexes remained unaffected. In supershift assays using NF-kappa B-specific antibodies, complex C2 was identified to be a p50 homodimer (KBF1) and complex C1 was identified as a p50/p65 heterodimer. Both complexes were formed within 10 min after addition of the bacteria. Since the synthesis of tumor necrosis factor alpha and interleukin-1 occurs at later times, these cytokines cannot be the mediators of enhanced NF-kappa B formation. Infection experiments with different nonhemolytic mutants of L. monocytogenes and the use of the phagocytosis inhibitor cytochalasin B suggest that events prior to invasion and escape of the bacteria from the phagosome into the cytoplasm enhance the nuclear transport of p50/p65 NF-kappa B components.

Animals↗
PubMed1993

[Drug-induced liver disease: experiences of the Swiss Center for Adverse Drug Effects 1989-1991].

Drug-induced liver disease can mimic any form of acute or chronic liver disease. Suspected drug-induced liver disease makes up between 4 and 7% of all reports of adverse drug effects voluntarily reported to central registries. We report on all patients with drug-induced hepatotoxic reactions voluntarily reported to the Swiss Adverse Drug Reaction Center from 1989 to 1991. In that period there was a total of 2084 reports of which 140 (6.7%) concerned the liver. In 16 cases two drugs were simultaneously involved, so that 156 investigations were carried out. We found a causal relationship in 123 cases. Antibiotic and chemotherapeutic agents were the drugs most frequently involved. There were seven fatal cases (5%). Our data correspond with the data in the literature. Regarding the amount of drugs prescribed, the hepatic adverse effect can be regarded as common.

Adolescent↗
PubMed1993

[Neurological side effects following vaccination of early-summer meningoencephalitis. Case report and experiences of the Swiss Center for Adverse Drug Effects].

Two weeks after vaccination against tick-born encephalitis (TBE) a 69-year-old patient developed subacute myelo-polyradiculitis. The neurological symptoms subsided after a few weeks. Alerted by this observation, we scanned the database of the Swiss Drug Monitoring Center (SANZ) for similar case reports. Of twenty spontaneous reports 11 concerned neurological side effects closely related to TBE vaccination. We conclude that TBE vaccination is associated with substantial neurological side effects and should, therefore, remain restricted to individuals at high risk for TBE.

Adolescent↗
PubMed1993

The circulating bioactive form of human guanylin is a high molecular weight peptide (10.3 kDa).

Guanylin is a peptide isolated from rat intestine that stimulates intestinal guanylate cyclase. We describe here the purification of circulating guanylin from human hemofiltrate. By N-terminal protein sequence analysis 47 amino acids were determined. This sequence corresponds to the positions 22 to 68 of the prohormone deduced from the cDNA sequence of human proguanylin. Mass spectral analysis of the circulating peptide showed the molecular weight to be 10,336 Da, which corresponds to the mass calculated from position 22 to the C-terminus of the peptide predicted from the cDNA sequence. Circulating guanylin markedly increased the cyclic GMP content of T84 cells. Our data show that the hormonal form of guanylin is circulating as a 10.3-kDa peptide in human blood.

Amino Acid Sequence↗
PubMed1993

MR imaging related to p.m. findings in angiodysgenetic myelomalacia. A case report.

In a 65-year-old patient with slowly progressive myelopathy of the lower spinal cord MRI revealed slight thickening of the conus medullaris and discrete serpiginous areas of low signal intensity in contact to the surface of the myelon. The T2-weighted axial images demonstrated a zone of high signal intensity within the center of the lumbosacral cord. These findings corresponded to the results of autopsy: cord enlargement, dilatation of wall thickened and partially thrombosed pial veins, edema, damage of the myelin sheath with development of foam cells, areas of hemorrhage and necrosis. Although myelography and spinal digital subtraction angiography had been normal in this case we assume that perhaps a spinal dural av-fistula may have been the cause of MR- and pathological findings which indicate an angiodysgenetic myelomalacia (Morbus Foix-Alajouanine). The pathogenesis of spinal dural av-fistulas is discussed in order to explain why angiography has been negative.

Aged↗