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Biomedical subjects

H Michel

Publications and source records attributed to H Michel.

At least 181 records · Page 10Linked to original sources
PubMed1993

[The value of laparoscopy in the staging of digestive system cancers].

Sixty two patients with a gastrointestinal carcinoma were evaluated pre-operatively by ultrasonography, CT scan and laparoscopy to seek liver metastases and/or peritoneal carcinomatosis. Performance levels of laparoscopy, ultrasonography and CT scan were comparable regarding the diagnosis of liver metastases. Laparoscopy was markedly better than CT scan and ultrasonography in the diagnosis of peritoneal carcinomatosis. Thus the investigation of choice for the detection of liver metastases is a single imaging technique. In contrast, if excision surgery is envisaged, all gastrointestinal carcinomas should be assessed by ultrasonography and/or CT scan and laparoscopy to definitely eliminate peritoneal carcinomatosis or small superficial liver metastases, in such a way as to avoid unnecessary laparotomy.

Carcinoma↗
PubMed1993

Optic tectum in congenitally monophthalmic fishes and chicks.

Morphometry of optic tectum layers was performed in fishes and birds that were congenitally monophthalmic (or had one very small or malformed eye). The optic chiasm was studied with regard to possible anomalies of the fiber distribution. In two very young fish larvae with only one ocular rudiment, no differences were found between the two tecta. In fishes and chicks with one normal and one eye of reduced size, the volume of superficial tectal layers contralateral to the small eye was significantly more affected (reduction by 40 to 70%) than that of the deep layers (reduction by 10 to 30%). Particularly pronounced differences between the superficial tectal layers of both sides were found in a fish where a thin optic nerve, originating in an unusually small eye, projected to the ipsilateral side of the brain. It is concluded that (1) the development of superficial tectal layers depends more strongly on optic innervation than that of deep layers; (2) obvious differences between tecta with and without optic innervation develop rather late in ontogeny; (3) there seems to be no measurable difference between effects of a poor (less than 25%) innervation of the tectum and a complete lack of this projection.

Anguilla↗
PubMed1993

[Stress and the digestive system].

Functional disorders mainly occur in young, anxious hyperactive, sometimes obsessional patients and involve all parts of digestive tract: feeling of obstruction the upper oesophagus or dysphagia; aerophagia related to a slow gastric emptying or gastric fullness relieved by eructation; biliary vomiting and pain in right abdominal upper quadrant which might correspond to a form of migraine without headache; irritable bowel, characterized by abdominal discomfort and constipation. Obviously, the diagnosis of functional disorders required elimination of an organic disease by appropriate endoscopic investigations. Psychosomatic disorders mainly comprise gastroduodenal ulcers and inflammatory bowel diseases. Although psychologic profiles have been associated with gastro-duodenal ulcer, these are not necessary for the development of the disease. The role of emotional factors has decreased since very efficient anti-secretory drugs are available. Inflammatory bowel diseases, in particular ulcerative colitis is frequently associated to behaviour disorders. The patient is usually a young woman brought up by an overprotective family. It is generally recognized that attacks of ulcerative colitis may be triggered by emotional factors. Thus, Stress may interact with digestive tract. In some cases, as in patients with irritable bowel or distal ulcerative colitis, psychotherapy such as Schultz's Autogenous Training, improves the patient's condition.

Arousal↗
PubMed1993

[Evolution of cutaneous changes observed in cirrhosis patients before and after liver transplantation].

UNLABELLED: In 11 patients with liver cirrhosis a prospective study concerning the evolution of skin changes before and after liver transplantation was performed. Etiology of the disease was: alcoholic in 5 cases, post-inflammatory in 4 cases and primary biliary cirrhosis in 2. Evolution of: nevi spiders, erythema palmar, changes in nails, Hippocrates fingers, discoloration of legs, bilateral Dupuytren's disease and gynecomastia (in man) were estimated. At the same time sex hormones levels were measured. One month after liver transplantation a reduction of total spiders number as well as the frequency of the erythema palmare and nails changes was observed. During the next few months we observed disappearance of the legs discoloration and signs of gynecomastia and Hippocrates fingers. Only the Dupuytren's contractures remained unchanged. There was no correlation between sex hormones levels and skin changes except decrease of the total testosterone level (p < 0.05) and an increase of free testosterone to total testosterone ratio (p < 0.02) in women and a decrease of estradiol level (p < 0.02) in women and a decrease of estradiol level (p < 0.002) in men after operation. CONCLUSION: skin changes typical for liver cirrhosis can be reversible after liver transplantation.

Adult↗
PubMed1992

Invariant chain peptides in most HLA-DR molecules of an antigen-processing mutant.

Class II major histocompatibility complexes bind peptides in an endosome-like compartment. When the class II null cell line 721.174 was transfected with class II DR3 genes, DR molecules were produced in normal amounts. However, the DR molecules were abnormally conformed and unstable because deletion of an antigen-processing gene had impaired intracellular formation of most class II-peptide complexes. Yet, 70 percent of the DR molecules still bore peptides, 80 percent of which were 21- to 24-amino acid fragments of the class II-associated invariant chain. These peptides were rare on DR3 from control cells. Thus, a defect in the main antigen-processing pathway revealed a process in which DR molecules bind long peptides derived from proteins present in the same compartment.

Amino Acid Sequence↗
PubMed1992

Renaturation and partial peptide sequencing of mitogen-activated protein kinase (MAP kinase) activator from rabbit skeletal muscle.

Mitogen-activated protein kinase (MAP kinase) activator was purified 2000-fold from skeletal muscle, and proteins which co-purified with the activator were analysed after SDS/PAGE by renaturation and partial sequencing. Activity for tyrosine and threonine phosphorylation of MAP kinase was present in two bands of approx. 48 and 46 kDa, which have sequence similarity to small GTP-binding protein p25 GDP dissociation inhibitor and protein kinases (PBS2, SPK1+, STE7, BYR1) respectively.

Amino Acid Sequence↗
PubMed1992

Hepatitis after germander (Teucrium chamaedrys) administration: another instance of herbal medicine hepatotoxicity.

OBJECTIVE: To show that germander (Teucrium chamaedrys), an herbal medicine used to facilitate weight loss, may be hepatotoxic and to delineate the nature of the injury. DESIGN: Retrospective study. SETTING: Liver units of several centers in the French Network of Pharmacovigilance. PATIENTS: Seven patients who developed hepatitis after germander administration and who had no other cause of liver injury. MEASUREMENTS: Clinical examination, liver function tests, various serologic tests, ultrasonography, and histologic study. RESULTS: Hepatitis characterized by jaundice and a marked increase in serum aminotransferase levels occurred 3 to 18 weeks after germander administration. Liver biopsy specimens in three patients showed hepatocyte necrosis. After discontinuing treatment with germander, jaundice disappeared within 8 weeks and recovery was complete in 1.5 to 6 months. In three cases, germander readministration was followed by the prompt recurrence of hepatitis. CONCLUSION: Germander may be hepatotoxic, which supports the view that herbal medicines are not always as safe as generally assumed.

Acute Disease↗
PubMed1992

Identification of Tyr-185 as the site of tyrosine autophosphorylation of recombinant mitogen-activated protein kinase p42mapk.

Tyrosine phosphorylation of 42-kDa mitogen-activated protein kinase (p42mapk) occurs during expression of the recombinant protein in Escherichia coli, as well as during in vitro phosphorylation of the protein purified from this source. Structural analyses were performed to identify the site(s) of tyrosine phosphorylation of recombinant p42mapk, both during expression of the protein in E. coli and during in vitro incubations with ATP/Mg2+/Mn2+. Mass spectrometry and phosphopeptide mapping showed that tyrosine phosphorylation of recombinant p42mapk occurs on Tyr-185, the site of regulatory tyrosine phosphorylation that occurs in mitogen-stimulated mammalian cells.

Amino Acid Sequence↗
PubMed1992

Peptides presented to the immune system by the murine class II major histocompatibility complex molecule I-Ad.

Between 650 and 2000 different peptides are associated with the major histocompatibility complex class II molecule I-Ad. Sequences for nine of these were obtained by a combination of automated Edman degradation and tandem mass spectrometry. All of the peptides are derived from secretory or integral membrane proteins that are synthesized by the antigen-presenting cell itself. Peptides were 16 to 18 residues long, had ragged NH2-and COOH-termini, and contained a six-residue binding motif that was variably placed within the peptide chain. Binding data on truncated peptides suggest that the peptide binding groove on class II molecules can be open at both ends.

Amino Acid Sequence↗
PubMed1992

Characterization of an improved reaction center preparation from the photosynthetic green sulfur bacterium Chlorobium containing the FeS centers FA and FB and a bound cytochrome subunit.

A photosynthetic reaction center complex was prepared from the green sulfur bacterium Chlorobium by solubilization of chlorosome-depleted membranes with lauryl maltoside, followed by anion-exchange chromatography and molecular sieve chromatography. The purified complex was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, optical spectroscopy, and EPR spectroscopy. The major bands migrated at apparent molecular masses of 50, 42, and 32 kDa (heme-staining) and additional weaker bands at 22, 15, and 12 kDa. The isolated reaction center complex contained about 40 bacteriochlorophyll alpha molecules per primary electron donor, P840, assayed by photooxidation. It was competent in stable low-temperature photoreduction of the FeS centers FA and FB. The spectra of these acceptors and their low-temperature photochemistry in the purified complex were the same as found in intact Chlorobium membranes and similar to what had been described for photosystem I from plants. Membrane-bound cytochrome c553 copurified with the reaction center complex. A ratio of about four hemes per P840 was determined. This result indicates that cytochrome c553 that is closely associated with the reaction center is a tetraheme cytochrome, as described for some purple bacteria.

Bacteriochlorophylls↗
PubMed1992

Characterization of peptides bound to the class I MHC molecule HLA-A2.1 by mass spectrometry.

Antigens recognized by T cells are expressed as peptides bound to major histocompatibility complex (MHC) molecules. Microcapillary high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry was used to fractionate and sequence subpicomolar amounts of peptides isolated from the MHC molecule HLA-A2.1. Of 200 different species quantitated, eight were sequenced and four were found in cellular proteins. All were nine residues long and shared a distinct structural motif. The sensitivity and speed of this approach should enhance the analysis of peptides from small quantities of virally infected and transformed cells as well as those associated with autoimmune disease states.

Amino Acid Sequence↗