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M Kuhn

Publications and source records attributed to M Kuhn.

At least 127 records · Page 7Linked to original sources
PubMed1996

cGMP-activating peptides do not regulate electrogenic electrolyte transport in principal cells of rat CCD.

K+ channels in the basolateral membrane of rat cortical collecting duct (CCD) are regulated by a cGMP-dependent protein kinase (J. Hirsch and E. Schlatter. Pfluegers Arch. 429: 338-344, 1995). Conflicting data exist on the effects of cGMP-activating agonists on Na+ transport in these cells. Thus we tested members of the family of peptides that increase intracellular cGMP [cardiodilatin/atrial natriuretic peptide (CDD/ANP), brain natriuretic peptide, C-type natriuretic peptide, urodilatin, guanylin, and uroguanylin], as well as bradykinin +/- CDD/ANP on membrane voltages (Vm) of principal cells of isolated rat CCD using the slow whole cell patch-clamp technique (E. Schlatter, U. Fröbe, and R. Greger. Pfluegers Arch. 421: 381-387, 1992). None of the agonists tested changed Vm significantly. There was also no effect of dibutyryl guanosine 3',5'-cyclic monophosphate (DBcGMP) on AVP-dependent lumen-to-bath Na+ flux, transepithelial voltage, or osmotic water permeability in isolated perfused rat CCD. Finally, CDD/ANP increased intracellular cGMP only in glomeruli but not in CCD. Thus the findings provide no evidence for control of electrogenic electrolyte transport by these natriuretic peptides in principal cells of rat CCD, and the agonist that physiologically regulates the cGMP-dependent K+ channels remains to be identified.

Animals↗
PubMed1996

Laboratory analysis.

Explore the source record for details and available documents.

Clinical Laboratory Techniques↗
PubMed1995

[Problems in the diagnosis and therapy of lymph node tuberculosis in HIV-negative patients].

Tuberculosis is the world's foremost cause of death from a single infectious agent in adults. During the past decade the nature and magnitude of the problem of tuberculosis have dramatically changed. Much of what physicians have learned about this disease is no longer true and tuberculosis has become a new entity. Migration from developing areas with a high prevalence of tuberculosis to industrialized countries, and the problem of HIV infection, have introduced new components to the epidemiology. We report three cases of young immigrants with lymph node tuberculosis. One patient was successfully treated with the usual 9-month-regimen. The other 2 patients, however, developed new lymph nodes or enlargement of existing nodes during treatment. They underwent further examinations, including surgical biopsies, because of diagnostic uncertainty (tuberculosis, superinfection or lymphoma). Finally the 2 patients were successfully treated with antituberculous agents for 12 and 15 months. These cases prompted a review of the literature and a reevaluation of the management of lymph node tuberculosis, including the value of surgical biopsy in the diagnosis of tuberculous lymphadenitis. We conclude that selective surgical biopsies should be recommended for differential diagnosis of tuberculous lymphadenitis. Histological examination (caseating epitheloid cell granulomas and giant cell formation) and microbiological examination (Ziehl-Neelsen staining and culture of native material) should be performed. Newer methods, such as amplification and detection of mycobacterial DNA, are rapid and sensitive tests helpful for diagnosis. Lymph nodes may increase in size and new nodes may appear both during and after chemotherapy, without indicating a failure of treatment or relapse. The usual treatment is a 9-month-regimen with rifamipicin, isoniazid, pyrazinamid and ethambutol. Prolonged or modified regimens are, however, necessary in some individuals.

Adult↗
PubMed1995

Pituitary adenylate cyclase-activating polypeptide stimulates cardiodilatin/atrial natriuretic peptide (CDD/ANP-(99-126) secretion from cultured neonatal rat myocardiocytes.

It has been reported that the highly homologous neuropeptides pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal polypeptide (VIP) exert similar cardiovascular effects in vivo. In the present study we compared the effects of these neuropeptides on myocardial cyclic AMP content and the release of immunoreactive CDD/ANP-(99-126) (atrial natriuretic peptide). In cultured neonatal rat cardiomyocytes PACAP and VIP evoke concentration-dependent increases in intracellular cyclic AMP content but responses to VIP are markedly less. PACAP stimulates the release of CDD/ ANP-(99-126) in a concentration-dependent manner with a threshold concentration of 1 nM, and up to a 6-fold increase in basal secretion at 1 microM PACAP. In contrast. VIP had no effect on the release of CDD/ANP. Pretreatment of cells with the competitive PACAP-antagonist, PACAP-6-38 (1 microM), significantly reduces the effects of PACAP on intracellular cyclic AMP and on CDD/ANP-(99-126) secretion and abolishes the effects of VIP on cyclic AMP. Pretreatment with VIP-receptor antagonist (1 microM) prevents the cyclic AMP-response to VIP while increases in cyclic AMP as well as stimulation of CDD/ANP-(99-126) release by PACAP are not affected. It is concluded that both neuropeptides directly influence cardiac myocytes through an increase in intracellular cyclic AMP. Release of CDD/ ANP-(99-126) by PACAP may be involved in the decrease in blood pressure that follows intravenous administration of this peptide. The higher potency of PACAP to induce cyclic AMP synthesis, its stimulating effect on the release of CDD/ANP-(99-126) and the finding that the VIP-receptor antagonist inhibits responses to VIP but not to PACAP suggest that PACAP activates cardiac myocytes through a PACAP-specific receptor.

Animals↗
PubMed1995

GCAP-II: isolation and characterization of the circulating form of human uroguanylin.

The systematic isolation of circulating regulatory peptides which generate cGMP as second messenger resulted in the identification of a novel member of the guanylin family. In the present study we describe the purification and amino acid sequence of a new guanylate cyclase C activating peptide (GCAP-II). GCAP-II contains 24 amino acids in the following sequence: FKTLRTIANDDCELCVNVACTGCL. Its molecular mass is 2597.7 Da. The 16 C-terminal amino acids are identical to uroguanylin from human urine. native and synthetic GCAP-II activate GC-C, the specific guanylate cyclase receptor, of cultured human colon carcinoma (T84) cells. GCAP-II stimulates chloride secretion in isolated human intestinal mucosa mediated by intracellular cGMP increase. GCAP-II specific antibodies were used to localize the peptide by immunohistochemistry in entero-endocrine cells of the colonic mucosa.

Amino Acid Sequence↗
PubMed1995

ENDOR studies of the primary donor cation radical in mutant reaction centers of Rhodobacter sphaeroides with altered hydrogen-bond interactions.

The electronic structure of the cation radical of the primary electron donor was investigated in genetically modified reaction centers of Rhodobacter sphaeroides. The site-directed mutations were designed to add or remove hydrogen bonds between the conjugated carbonyl groups of the primary donor, a bacteriochlorophyll dimer, and histidine residues of the protein and were introduced at the symmetry-related sites L168 His-->Phe, HF(L168), and M197 Phe-->His, FH(M197), near the 2-acetyl groups of the dimer and at sites M160 Leu-->His, LH(M160), and L131 Leu-->His, LH(L131), in the vicinity of the 9-keto carbonyls of the dimer. The single mutants and a complete set of double mutants were studied using EPR, ENDOR, and TRIPLE resonance spectroscopy. The changes in the hydrogen bond situation of the primary donor were accompanied by changes in the dimer oxidation midpoint potential, ranging from 410 to 710 mV in the investigated mutants [Lin, X., Murchison, H. A., Nagarajan, V., Parson, W. W., Williams, J. C. & Allen, J. P. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 10265-10269]. It was found that the addition or removal of a hydrogen bond causes large shifts of the spin density between the two halves of the dimer. Measurements on double mutants showed that the unpaired electron can be gradually shifted from a localization on the L-half of the dimer to a localization on the M-half, depending on the hydrogen bond situation. As a control, the effects of the different hydrogen bonds on P.+ in the mutant HL(M202), which contains a BChlL-BPheM heterodimer as the primary donor with localized spin on the BChl aL [Bylina, E. J., & Youvan, D. C. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7226-7230; Schenck, C. C., Gaul, D., Steffen M., Boxer S. G., McDowell L., Kirmaier C., & Holten D. (1990) in Reaction Centers of Photosynthetic Bacteria (Michel-Beyerle M. E., Ed.) pp 229-238, Springer, Berlin] were studied. In this mutant only small local changes of the spin densities (< or = 10%) in the vicinity of the hydrogen bonds were observed. The effects of the introduced hydrogen bonds on the spin density distribution of the dimer in the mutants are discussed in terms of different orbital energies of the two BChl a moieties which are directly influenced by hydrogen bond formation. The observed changes of the spin density distribution for the double mutants are additive with respect to the single mutations.(ABSTRACT TRUNCATED AT 400 WORDS)

Cations↗
PubMed1995

Modification of the Fontan procedure. Superior vena cava to left pulmonary artery connection and inferior vena cava to right pulmonary artery connection with adjustable atrial septal defect.

BACKGROUND: A modification of the Fontan procedure with unidirectional cavopulmonary connection is described in which the superior vena cava (SVC) is connected to the left pulmonary artery (PA) and the inferior vena cava (IVC) is connected to the right PA via a lateral tunnel with a snare-controlled, adjustable atrial septal defect (ASD). This allows matching of the SVC and IVC flows with the lung of appropriate size. The obligatory left Glenn shunt provides an adequate arterial oxygen saturation, and the elevation in SVC pressure is well tolerated. The adjustable ASD allows selective decompression of the IVC that maintains cardiac output and reduces fluid accumulation in the serous cavities. METHODS AND RESULTS: Since March 1992, we have performed this procedure in 18 patients. There were 17 children and 1 adult. Median age was 3 years and 9 months (range, 13 months to 36 years). Six patients had been staged with a previous bidirectional Glenn shunt. Preoperative cardiac catheterization revealed a PA pressure of 13 +/- 2 mm Hg and a transpulmonary gradient of 5 +/- 3 mm Hg. Ventricular function was satisfactory in all patients. At the completion of bypass, the pressures in the SVC and IVC were 16 +/- 4 mm Hg and 10 +/- 3 mm Hg, respectively (P < .01). The left atrial pressure was 6.0 +/- 3.0 mm Hg and the arterial O2 saturation on 100% oxygen was 93 +/- 3%. There was one death as a result of intractable atrial arrhythmias. The remaining 17 patients had a mean hospital stay of 9.7 days (6 to 18 days). The length of pleural drainage was 7 +/- 3 days. The ASD was adjusted in 11 patients before discharge. Oxygen saturation at discharge was 85.4 +/- 4%. Nine patients had repeat catheterization. The ASD was completely closed in 6 patients, an average of 2.5 months after surgery (range, 3 weeks to 5 months). After ASD closure, the arterial oxygen saturation was 96 +/- 3%, and the SVC and IVC pressures were both 13 +/- 3 mm Hg. CONCLUSIONS: The Fontan procedure with unidirectional cavopulmonary connection and adjustable ASD has several advantages that may reduce mortality and morbidity for the high-risk Fontan candidate.

Adolescent↗
PubMed1995

[Drug-induced pancreatitis: experience of the Swiss Drug Adverse Effects Center (SANZ) 1981-1993].

Acute pancreatitis may be caused by a number of different drugs. However, reports on the frequency of drug-related acute pancreatitis and on the drugs involved are rare. We therefore investigated all cases of drug-related acute pancreatitis which had been reported to the Swiss Drug Monitoring Center (Schweizerische Arzneimittel-Nebenwirkungszentrale, SANZ) between 1981 and 1993. During this period the total number of reported adverse drug reactions was 7338, 20 of which (0.3%) were considered to be probable cases of drug-related pancreatitis. In 18 cases a single drug was incriminated, whereas in two cases two and four drugs respectively had to be investigated. Serious courses, deaths, or chronic pancreatitis were not reported. The most frequent single drugs incriminated were sulfonamide derivatives (5 cases), valproic acid (3 cases) and nonsteroidal anti-flammatory drugs (2 cases). The frequencies reported here are consistent with the literature. Considering the total number of drugs prescribed, acute pancreatitis is a rare adverse drug reaction.

Acute Disease↗
PubMed1995

[Meningoencephalo-myeloradiculitis due to Flavivirus: bi-brachial paralysis and respiratory insufficiency].

3 patients developed rapid onset of fever and nuchal stiffness. Paresis of brachial muscles occurred within 4 days and all patients had respiratory failure that needed mechanical ventilation. At the peak of the disease there were bilateral asymmetrical severe atrophy of brachial, shoulder and neck muscles, cranial nerve pareses and absent or weak deep reflexes in the upper extremities. CSF analyses showed sterile lymphocytic pleocytosis. In 2 cases the patients suffered a tick bite in Switzerland and the third was probably bitten by an insect while opening a package received from Indonesia. Patients had rapid defervescence and serological tests were found to be highly positive for IgM and then IgG ELISA FSME (Frühsommer-Meningoenzephalitis). The patients were ventilated for 2 to 5 weeks before a progressive improvement was seen. However, on follow-up at 12, 18 and 30 months respectively, proximal muscles were still atrophied and quite weak. Our cases underline that: (1) FSME-ELISA results may cross-react with the Japanese and Central European encephalitis virus species; (2) Flaviviruses do induce unusual and preferential long-term paralysis of the upper extremities simulating poliomyelitis; (3) in the 2 patients studied electrophysiologically, there were signs of axonal reinnervation not seen in lower motor neuron syndrome which were important for reinnervation to permit progressive, but late, motor improvement; (4) there is no evidence of extension of the endemic foci of tick-borne encephalitis in Switzerland.

Adult↗
PubMed1995

Analysis of the human guanylin gene and the processing and cellular localization of the peptide.

The complete cell biological analysis of human guanylin, a recently discovered regulatory peptide, is offered in this investigation: (i) the nucleotide sequence of the gene, (ii) the isolation and characterization of its circulating molecular form, and (iii) its localization in enterochromaffin cells of the gut. As determined by molecular cloning, DNA sequencing, and comparison with the known cDNA sequence, the approximately 2.6-kbp large gene consists of three exons interrupted by two introns. The putative promoter region contains a TTTAAAA sequence motif and several potential binding sites for transcription factors such as AP-1, AP-2, Sp 1, and glucocorticoid receptors. The isolated hormonal form of guanylin is a 94-amino acid peptide with a molecular mass of 10.3 kDa. Western blot analysis of RP-HPLC fractions from blood plasma confirms this molecular form. Thus, guanylin is synthesized by gut enterochromaffin cells as a prohormone of 115 amino acids and is processed to the molecular form of 94 amino acids circulating in the blood.

Amino Acid Sequence↗
PubMed1995

Site-directed mutagenesis of conserved histidines in the helix VIII domain of PsaB impairs assembly of the photosystem I reaction center without altering spectroscopic characteristics of P700.

The chloroplast psaB gene encodes one of the polypeptides of the photosystem I reaction center heterodimer that coordinates the electron transfer components P700, A0, and A1. Histidine residues in the most highly conserved region of the PsaB protein are predicted to coordinate the P700 reaction center chlorophyll(s) and the initial electron acceptor, A0. Oligonucleotide-mediated site-directed mutagenesis and chloroplast transformation of Chlamydomonas reinhardtii have been used to determine the importance of these conserved histidines in photosystem I reaction center biogenesis and function. It is demonstrated that these histidine residues are essential for stable accumulation of the photosystem I reaction center. Protein pulse-labeling shows that changing the histidine residues impairs a post-translational step in reaction center assembly. Photosystem I complexes from the mutants have been characterized by Electron Nuclear Double Resonance and Electron Spin Echo Envelope Modulation spectroscopy to determine the impact of any mutations on P700+. In all cases we determine that spectroscopic characteristics of P700+ remain unchanged. The implications of these results to current models of the photosystem I reaction center and related bacterial reaction centers are discussed.

Amino Acid Sequence↗
PubMed1995

Late outcome of percutaneous dilatational tracheostomy in intensive care patients.

OBJECTIVE: Percutaneous dilatational tracheostomy is increasingly practiced in intensive care units and has a low incidence of early complications. The late effects of this procedure are still poorly known and were the focus of this study. DESIGN: Prospective descriptive clinical study. SETTING: Interdisciplinary intensive care unit in a 300-bed teaching hospital. PATIENTS: A consecutive group of critically ill patients who underwent percutaneous tracheostomy between Nov. 90 and March 93, surviving at least 2 months after decannulation. MEASUREMENTS AND RESULTS: There were 17 patients fulfilling the inclusion criteria and 16 of them were seen and examined. The follow-up protocol required a formal standardized patient interview, a physical examination of the stoma site and a fiberoptic laryngotracheoscopy. Results of these sub-tests and overall outcome rating were standardized and expressed as good, moderate or poor. Subjective rating was good in all patients. All denied suffering from any side effects of their tracheostomy. Clinical examination revealed neither stridor nor hoarseness in any of the patients. Most of the scars were whitish and less than 1 cm in length, a few were sunken in, none had adhesions. In 15 patients the clinical result was good and in one, moderate (whitish, sunken-in scar, longer than 2 cm). Ten patients underwent tracheoscopy, while 6 did not. There were no signs of significant stenosis or tracheomalacia. In 8 patients with minor findings results were scored as good, while 2 were classified as moderate (combination of swelling and scar formation of a string-like membrane). The overall rating was good in 13 patients (81%) and moderate in 3 patients (19%). There were no poor outcomes. CONCLUSIONS: Late outcome of percutaneous dilatational tracheostomy in critically ill patients is mostly good. Pending further studies, the use of this technique in intensive care units appears justified.

Adult↗
PubMed1995

Circulating and tissue guanylin immunoreactivity in intestinal secretory diarrhoea.

Guanylin is a recently discovered peptide hormone that activates intestinal guanylate cyclase (GC-C) and thereby stimulates intestinal chloride secretion. Immunohistochemistry showed its presence in enterochromaffin (EC) cells of the gut. In vitro studies suggested that guanylin plays an important role in the endogenous modulation of intestinal salt and water secretion. In the present study the concentration of circulating immunoreactive (IR)-guanylin in plasma of patients with intestinal diarrhoea due to chronic bowel inflammation and patients with carcinoid tumours were measured with a specific radioimmunoassay. In 22 patients with Crohn's disease and eight patients with ulcerative colitis, plasma concentrations of IR-guanylin were 44 +/- 3 and 42 +/- 4 fmol mL-1, respectively. Levels were not different from that in 44 healthy volunteers suggesting that the circulating hormone is not involved in diarrhoea of these patients. In 17 patients with symptomatic carcinoid tumors the median concentration of circulating IR-guanylin was significantly enhanced (94 +/- 16 fmol mL-1, range 37-312 fmol mL-1). Immunohistochemistry revealed the presence of immunoreactive guanylin in carcinoid tissues, suggesting that these tumours co-release guanylin along with their usual resident hormone, serotonin. Enhanced local secretion of guanylin may play a causal role in diarrhoea of these patients and its elevation in plasma may be of diagnostic value in this type of endocrine tumours.

Adult↗
PubMed1995

Salmonella strain secreting active listeriolysin changes its intracellular localization.

We describe the construction of an attenuated Salmonella dublin aroA strain which secretes via the Escherichia coli hemolysin secretion machinery an active hybrid cytolysin consisting of listeriolysin from Listeria monocytogenes and the C-terminal secretion signal of E. coli hemolysin. This hemolytic S. dublin strain is partially released into the cytoplasm of the host cell following uptake by J774 macrophage cells, whereas the nonhemolytic control S. dublin aroA strain remains in the phagosome.

Animals↗
PubMed1994

[Localized pulmonary edema in the right upper lobe--an important differential diagnostic hint for acute mitral insufficiency].

Differential diagnosis of unilateral alveolar pulmonary infiltration includes various possibilities. Acutely developing mitral insufficiency, often without any prior cardiac symptoms, may be the cause of pulmonary edema localized exclusively in the right upper lobe. This unusual and often misinterpreted radiologic presentation is brought to attention by two case reports.

Acute Disease↗
PubMed1994

Segmental differences in the effects of guanylin and Escherichia coli heat-stable enterotoxin on Cl- secretion in human gut.

1. Mucosally added synthetic guanylin and Escherichia coli heat-stable enterotoxin (STa) increased short-circuit current (ISC) across isolated muscle-stripped human intestine in vitro. 2. Serosal bumetanide inhibited ISC responses indicating that guanylin and STa stimulate electrogenic chloride secretion. 3. ISC responses were markedly greater in the colon than in the jejunum. 4. Pretreatment with indomethacin did not significantly alter the effects of guanylin and STa. 5. Both peptides induced concentration-dependent increases in the cyclic GMP content of human intestinal mucosa in vitro; cyclic AMP levels remained unchanged. 6. In contrast to ISC responses, increases in cyclic GMP content induced by guanylin and STa were markedly greater in the jejunum than in the colon. 7. Sodium nitroprusside (SNP) but not human alpha-atrial natriuratic peptide (CDD/ANP(99-126)) increased chloride secretion in human intestine; both agents induced small increases in intestinal cyclic GMP content. 8. Guanylin, STa and the nitric oxide (NO) donor SNP increased electrogenic chloride secretion across human intestinal mucosa in vitro by stimulation of cyclic GMP. The discrepancy between the effects on chloride secretion and intracellular cyclic GMP content suggest different cellular action sites of guanylin and STa in human small and large intestine.

Atrial Natriuretic Factor↗