Search PubMed⌕ Search

Biomedical subjects

H Michel

Publications and source records attributed to H Michel.

At least 253 records · Page 14Linked to original sources
PubMed1989

[Prevention of recurrent hemorrhage caused by the rupture of esophageal varices in cirrhotic patients. A controlled study of propranolol and clip ligation of the esophagus].

Among the various treatments of ruptured oesophageal varices two seem to be effective: oral propranolol therapy and ligation of the oesophagus on clip. In this controlled study these two methods were compared in a series of 55 patients hospitalized for ruptured oesophageal varices. After haemodynamic stability was obtained, the patients were allocated at random to either propranolol therapy (n = 28) or surgery (n = 27). Twenty-one per cent of these patients belonged to group C of Child's classification and 54 per cent to group A. The parameters studied were similar in both groups. Five patients were excluded from the study: 2 in the medical group when it appeared that propranolol was contra-indicated and 3 in the surgical group who died before the operation; however, these 5 patients were taken into account in a second statistical evaluation. Nineteen out the 26 patients under propranolol (73 per cent) had rebleeding (within the first 10 days in 3 cases). In the surgical group recurrent bleeding was observed in 4 out of the 24 patients (17 per cent), and 4 other patients died post-operatively. The difference in favour of the surgical group was highly significant (P less than 0.001), and it remained significant (P less than 0.05) when the 5 patients who could not be treated were included into the calculations. Cox's multivariate analysis showed that patients in Child's C group had a poorer prognosis.

Adult↗
PubMed1989

Characterization of four herbicide-resistant mutants of Rhodopseudomonas viridis by genetic analysis, electron paramagnetic resonance, and optical spectroscopy.

Herbicides of the triazine class block electron transfer in the photosynthetic reaction centers of purple bacteria and PSII of higher plants. They are thought to act by competing with one of the electron acceptors, the secondary quinone, QB, for its binding site. Several mutants of the purple bacterium Rhodopseudomonas viridis resistant to terbutryn [2-(methylthio)-4-(ethylamino)-6-(tert-butylamino)-s-triazine] have been isolated by their ability to grow photosynthetically in the presence of the herbicide. Sequence analysis of the genes coding for the L and M subunits of the reaction center showed that four different mutants were obtained, two of them being double mutated: T1 (SerL223----Ala and ArgL217----His), T3 (PheL216----Ser and ValM263----Phe), T4 (TyrL222----Phe), and T6 (PheL216----Ser). The residues L223 and L216 are involved in binding of QB, whereas L217 and L222 are not. M263 is part of the binding pocket of the primary quinone, QA. The affinity of the reaction centers for terbutryn and the electron transfer inhibitor o-phenanthroline, determined via the biphasic charge recombination after one flash, is decreased for all mutants. The affinity for ubiquinone 9 is also decreased, except in T1. Characterization by EPR spectroscopy showed that the QB.-Fe2+ signal of T4, having a g = 1.93 peak, is different from the signals obtained with the wild type and the other mutants but very similar to those of Rhodospirillum rubrum and PSII. The results obtained by the combination of these different techniques are discussed with respect to the three-dimensional structure of the wild type and the mode of binding of ubiquinone, terbutryn, and o-phenanthroline as determined by X-ray structure analysis.

Amino Acid Sequence↗
PubMed1989

A truncated analog of a pre-light-harvesting chlorophyll a/b protein II transit peptide inhibits protein import into chloroplasts.

It is unclear how transit peptides target nuclear-encoded precursor proteins to the chloroplast. This study establishes the feasibility of using synthetic peptides as competitive inhibitors of chloroplast protein import and as probes for the function of domains within transit peptides. We show that peptide pL(1-20), MAASTMALSSPAFAGKAVNY, an analog of the NH2 terminus of a pre-light harvesting chlorophyll a/b protein II from Arabidopsis, inhibits the import of several Arabidopsis and pea precursor proteins into pea chloroplasts. Inhibition occurs at a step between the initial binding of precursors to the chloroplast and the first proteolytic cleavage event and is not due to interference with ATP availability or chloroplast integrity. Presumably this reflects specific binding of the peptide to the import machinery in the chloroplast envelope. Our data are consistent with the suggestion (Karlin-Neumann, G. A., and Tobin, E. M. (1986) EMBO J. 5, 9-13) that two conserved blocks of amino acids near the NH2-terminus of transit peptides (spanned by peptide pL(1-20] participate in protein targeting. Computer analysis also shows peptide pL(1-20) lacks the amphiphilic properties characteristic of pre-sequences of many nuclear-encoded mitochondrial proteins. This shows a difference in the mechanisms for targeting proteins to chloroplasts and mitochondria.

Amino Acid Sequence↗
PubMed1989

Nobel lecture. The photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis.

In our lectures we first describe the history and methods of membrane protein crystallization, before we show how the structure of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis was solved. Then the structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Finally we draw conclusions on the structure of the photosystem II reaction centre from plants and discuss the aspects of membrane protein structure. Sections 1 (crystallization), 4 (conclusions on the structure of photosystem II reaction centre and evolutionary aspects) and 5 (aspects of membrane protein structure) were presented and written by H.M., Sections 2 (determination of the structure) and 3 (structure and function) by J.D. We have arranged the paper in this way in order to facilitate continuous reading.

Amino Acid Sequence↗
PubMed1989

The photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis.

We first describe the history and methods of membrane protein crystallization, and show how the structure of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis was solved. The structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Finally we draw conclusions on the structure of the photosystem II reaction centre from plants and discuss the aspects of membrane protein structure.

Amino Acid Sequence↗
PubMed1989

The increase in urinary excretion of 6 beta-hydroxycortisol as a marker of human hepatic cytochrome P450IIIA induction.

1. Urinary excretion of 6 beta-hydroxycortisol, hepatic microsomal cortisol 6 beta-hydroxylase and the specific content of several forms of cytochrome P450 were measured in 8 to 14 patients before and after treatment with rifampicin (600 mg orally per day for 4 days). 2. Rifampicin treatment produced an average five fold increase in daily excretion of urinary 6 beta-hydroxycortisol. 3. Cortisol 6 beta-hydroxylase activity increased from 15 +/- 6 pmol min-1 mg-1 in organ donors (considered as 'control subjects') to 87 +/- 31 pmol min-1 mg-1 in rifampicin treated patients. 4. Among three forms of human P450 (P450IA, IIC and IIIA), (1), (2), measured by Western blots, only P450IIIA was significantly induced by the antibiotic. 5. Only antibodies against P450IIIA selectively inhibited cortisol 6 beta-hydroxylase in human liver microsomes. 6. Cortisol 6 beta-hydroxylase was correlated with P450IIIA specific content. 7. The urinary level of 6 beta-hydroxycortisol correlated with liver microsomal cortisol 6 beta-hydroxylase and P450IIIA specific content. 8. We conclude that P450IIIA is predominantly responsible for cortisol 6 beta-hydroxylase activity in human liver microsomes and that urinary 6 beta-hydroxycortisol is a marker of the induction of this cytochrome P450.

Adult↗
PubMed1989

Inhibitory effect of the C-terminal octapeptide of oxyntomodulin on pentagastrin-stimulated gastric acid secretion in man.

The effect of the C-terminal octapeptide of human oxyntomodulin (KA-8) on pentagastrin-stimulated gastric acid secretion was studied versus placebo in eight human volunteers after an overnight fast, using a double-blind randomized protocol. KA-8 (7.5 nmol/kg body weight) was bolus-injected at a plateau stimulation obtained with pentagastrin (3 micrograms/kg/h). KA-8 significantly decreased the volume secreted by 36% (p less than 0.025) and the acid output by 32% (p less than 0.025) 20 min after injection. The areas under the curve were significantly reduced for volume and acid output during the 1st h after peptide injection.

Adult↗
PubMed1989

Rioprostil, a new prostaglandin E1 analogue, in the once-daily treatment for the prevention of duodenal ulcer recurrence: a comparison with ranitidine.

The efficacy of Rioprostil (a new prostaglandin E1 analogue) is compared with that of ranitidine in the recurrence prevention of duodenal ulcer(s). Duration of treatment is 6 months. Ninety-seven patients received rioprostil, 600 micrograms once-daily orally, and 110 patients received ranitidine, 150 mg once-daily orally. On rioprostil, 14.9% of patients showed a relapse after 6 months compared to 10.1% on ranitidine. Diarrhoea occurred in 7 patients on rioprostil and 3 patients on ranitidine. Rioprostil given 600 micrograms daily in the evening is a highly effective treatment for the prevention of duodenal ulcer relapse, the efficacy not being significantly different from ranitidine 150 mg.

Adult↗
PubMed1989

[Efficacy and tolerability of enprostil in the treatment of duodenal ulcer. Comparison with cimetidine].

Enprostil, a synthetic PGE2, has been shown to have an inhibitory effect on gastric acid secretion, a mucoprotective effect and a postprandial lowering effect on gastrin. A double blind randomized study was performed in 80 patients, in order to evaluate the efficacy and safety enprostil (35 mu b.i.d) as compared to cimetidine (400 mg b.i.d) in duodenal ulcer. Healing rates after two, four and six weeks of treatment, as based on endoscopic evaluation, were 35, 72 and 83 p. 100 for enprostil and 45, 73 and 83 p. 100 for cimetidine, respectively. There were no significant differences between treatment groups. The time to relief of nighttime and daytime ulcer pain and antacid consumption were similar in the two groups. The patient's overall subjective assessment was better in the cimetidine group, but this was not confirmed by physicians' opinions. Diarrhea was observed in 7 p. 100 of patients treated by enprostil compared with 5 p. 100 for patients treated by cimetidine. One enprostil treated patient withdrew from the trial prematurely because of abdominal pain. This study demonstrates the efficacy and safety of enprostil in the treatment of active duodenal ulcer at the dosage of 35 micrograms twice daily.

Adult↗
PubMed1989

[Collagen colitis. Reflections apropos of 40 patients].

The aim of this study was to evaluate the frequency of a thickened subepithelial collagen band in the colon, its relationship to diarrhea, and the clinical relevance of its detection. During a 3.5 year period (May 1985-January 1989), a total of 3,323 biopsy specimens were obtained during 6,254 colonoscopies. A subepithelial collagen thickening greater than 10 microns was found in 40 patients (1.5 percent of the patients). Further assessment of these 40 patients showed that this histological lesion was characterized by a frequent association with chronic diarrhea (in 36 patients, i.e. 90 percent) whatever the cause, with diseases such as diabetes mellitus (8 cases) or inflammatory arthropathies (6 cases) and with a microscopic colitis in all cases. Course of collagen thickening was variable and independent of clinical course. Diarrhea was a constant finding when the collagen thickening was greater than 15 microns and frequently improved (12 patients/14) during treatment with Collagenan. This study suggests that a subepithelial thickened collagen band is an uncommon change in the colon and is frequently associated with chronic diarrhea. The significance of this morphological change is unknown, and its contribution to the pathogenesis of the diarrhea remains questionable.

Chronic Disease↗
PubMed1989

[Peroperative enteroscopy in recurrent hemorrhage of the small intestine].

Two cases of severe, recurrent gastrointestinal bleeding due to a small vascular lesion of the small intestine are presented. In the two patients, the diagnosis was established by intra-operative enteroscopy; in the first patient during laparotomy carried out after negative preoperative investigations; in the second, 48 hours after a right ileo-colic resection was performed for Crohn's disease of the ileum thought to be the cause of the bleeding. These two cases confirm that intra-operative enteroscopy is a very effective method to detect bleeding from small intestinal lesions, and that it should be used when pre-operative investigations and intraoperative examination are unsuccessful.

Adult↗
PubMed1989

[Double-blind controlled study of the efficacy of nifuroxazide versus placebo in the treatment of acute diarrhea in adults].

In a double-blind, controlled randomized trial, 88 adult patients with acute diarrhea (more than three watery stools per day) received either 400 mg of nifuroxazide twice daily or placebo for 5 days. The mean duration of diarrhea in the nifuroxazide group was 2.09 days versus 3.26 days in the placebo group (p less than 0.004). The number of bowel movements per day diminished and mucus disappeared more quickly in patients treated by nifuroxazide than in patients of the placebo group. Nifuroxazide was well tolerated and no side effects were observed. Nifuroxazide is an effective therapy for acute diarrhea and can be prescribed from the onset of diarrhea without waiting for stool culture results which can be late or negative.

Acute Disease↗
PubMed1989

[Chronic hepatic encephalopathy in cirrhotic patients and spontaneous portacaval anastomosis. Portal angiographic and manometric study].

Portal angiographic and manometric studies were prospectively carried out in 9 cirrhotic patients with spontaneous chronic portal-systemic encephalopathy. Hepatic encephalopathy presented as coma in 8 patients, and was the first manifestation of chronic liver disease in 6 cases. Hemodynamic studies showed a) a large single spontaneous portacaval anastomosis (gastrorenal, splenorenal, gradient (mean +/- SD = 16.3 +/- 5.4 mm Hg); c) a wedge hepatic venous pressure higher than portal pressure in 8 cases (difference: 1-11 mm Hg).

Blood Pressure Determination↗
PubMed1989

[Measurement of the sus-hepatic pressure gradient in differential diagnosis of chronic persistent or active hepatitis].

The value of the hepatic venous pressure gradient, measured during a transjugular liver biopsy procedure, was evaluated in the differential diagnosis of chronic persistent versus active hepatitis. The diagnosis of chronic persistent or active hepatitis was carried out according to classical clinical, biological, and above all pathological criteria. Patients with chronic active hepatitis were divided in to subgroups according to the degree of aggressivity and the presence of cirrhosis. Of the 70 patients studied, 13 had a gradient lower than 0.79 kPa, and all had chronic persistent hepatitis; 48 patients had a gradient higher than 0.93 kPa, they all had a chronic active hepatitis. For the 9 remaining patients, the gradient was between 0.79 and 0.93 kPa, 3 had persistent hepatitis, and 6 had active hepatitis. There was no significant variation of the gradient according to aggressivity in the subgroups of chronic active hepatitis. The gradient separated clearly chronic active hepatitis with or without cirrhosis. The measurement of the hepatic venous pressure gradient allows to differentiate between chronic persistent versus active hepatitis in 87 p. 100 of cases. This simple procedure offers a quick clue to diagnosis before obtaining histologic results.

Blood Pressure Determination↗