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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 307 records · Page 17Linked to original sources
PubMed1995

Characterization and solubilization of novel aldosterone-binding proteins in porcine liver microsomes.

Using the radioligand [1,2,6,7-3H]aldosterone ([3H]aldosterone), specific binding sites for aldosterone were identified and characterized in microsomal preparations from porcine liver. The maximum binding capacity is approximately 700 fmol x mg-1 microsomal protein. The reversible binding of [3H]aldosterone was saturable and Scatchard analysis revealed two apparent dissociation constants (Kd), Kd1 < or = 11 nM and Kd2 = 118 nM. Binding was optimal at pH 7.2, thermolabile, and was reduced by more than 70% when membrane vesicles were pretreated with trypsin. Binding was selective for aldosterone with cortisol being a weak agonist at 1000-fold higher concentrations only. Among those detergents tested to optimize conditions for solubilization, n-octylglucoside (75 mM) was most favorable and solubilized 25% of the radioligand-binding protein complex in the undissociated form. These binding sites have unique pharmacological properties, which are similar to those found for aldosterone membrane binding in human lymphocytes and pig kidney, and for rapid aldosterone effects on sodium-proton exchange.

Aldosterone↗
PubMed1995

Isolation of two Arabidopsis cDNAs involved in early steps of molybdenum cofactor biosynthesis by functional complementation of Escherichia coli mutants.

Most organisms appear to have a molybdenum cofactor consisting of a complex of molybdenum and a pterin derivative. Very little is known about molybdenum cofactor biosynthesis in plants or other eukaryotes, because the instability of the cofactor and its precursors makes it difficult to analyze this pathway. We have isolated two cDNA clones from the higher plant Arabidopsis thaliana encoding genes involved in early steps of molybdenum cofactor biosynthesis. The cDNAs were obtained by functional complementation of two Escherichia coli mutants deficient in single steps of molybdenum cofactor biosynthesis. The two cDNAs, designated Cnx2 and Cnx3, encode proteins of 43 and 30 kDa, respectively. They have significant identity to the E. coli genes, moaA and moaC, involved in molybdenum cofactor biosynthesis. Both genes have N-terminal extensions that resemble targeting signals for the chloroplasts or the mitochondria. Import studies with the translated proteins and purified mitochondria and chloroplasts did not show import of these proteins to either of these organelles. Northern analysis show that Cnx2 is expressed in all organs and strongest in roots. Cnx3 is not expressed in abundant levels in any tissue but roots. For both genes there is no detectable difference in the expression level from plants grown with nitrate or with ammonium. The Cnx2 gene has been mapped to chromosome II. Southern analysis suggests that both genes exist as single copies in the genome.

Amino Acid Sequence↗
PubMed1995

Post-transcriptional regulation of nitrate reductase by light is abolished by an N-terminal deletion.

Higher plant nitrate reductases (NRs) carry an N-terminal domain whose sequence is not conserved in NRs from other organisms. A gene composed of a full-length tobacco NR cDNA with an internal deletion of 168 bp in the 5' end fused to the cauliflower mosaic virus 35S promoter and appropriate termination signals was constructed and designated as delta NR. An NR-deficient mutant of Nicotiana plumbaginifolia was transformed with this delta NR gene. In transgenic plants expressing this construct, NR activity was restored and normal growth resulted. Apart from a higher thermosensitivity, no appreciable modification of the kinetic parameters of the enzyme was detectable. The post-transcriptional regulation of NR by light was abolished in delta NR transformants. Consequently, deregulated production of glutamine and asparagine was detected in delta NR transformants. The absence of in vitro delta NR activity modulation by ATP suggests the impairment of delta NR phosphorylation and thereby suppression of delta NR post-translational regulation. These data imply that post-transcriptional control of NR expression is important for the flow of the nitrate assimilatory pathway.

Adenosine Triphosphate↗
PubMed1995

Lymphocytic Na(+)-H+ exchange increases after an oral glucose challenge.

The effects of oral glucose challenge on plasma glucose concentration, plasma insulin concentration, arterial blood pressure, cytosolic pH (pHi), cytosolic free Na+ concentration ([Na+]i), and cellular Na(+)-H+ exchange activity were investigated in 16 healthy subjects. The pHi, [Na+]i, and Na(+)-H+ exchange activity were measured in intact lymphocytes by using the fluorescent dye technique. The oral glucose challenge significantly increased plasma glucose, plasma insulin, and the lymphocytic Na(+)-H+ exchange activity, measured as change of pHi per second (control [0 hours], 5.20 +/- 0.53 x 10(-3) dpHi/s; 1 hour after glucose administration, 8.28 +/- 1.07 x 10(-3) dpHi/s; 2 hours after glucose administration, 8.15 +/- 1.18 x 10(-3) dpHi/s; P = .002). The lymphocytic Na(+)-H+ exchange was significantly correlated with plasma glucose concentration (r = .357, P = .041). During steady state euglycemic hyperinsulinemic clamp, the Na(+)-H+ exchange activity was not significantly changed compared with baseline values. The study shows that changes of blood glucose levels can induce an acute increase in Na(+)-H+ exchange activity. Systolic blood pressure and Na(+)-H+ exchange activity were significantly (P < .001) but weakly correlated during an oral glucose challenge.

Adult↗
PubMed1995

[The value of 3-dimensional computed tomography in the preoperative evaluation of mandibular condyle fractures].

The recent expansion of surgical treatment for displaced condylar neck fractures should rely on a precise and careful preoperative radiological assessment. Two goals must be achieved. First the diagnosis must be confirmed by usually sufficient conventional imaging. Secondly, all the features of the fracture have to be analysed to come to the surgical decision and to choose the best osteosynthesis technique. Compared to traditional imaging, three dimensional computed tomography offers the possibility of a direct viewing. The extend of the fracture, the aspect and degree of displacement of the condylar fragment in relation to the ramus or the fossa are easily assessed. The examination and the integration of multiple axial or coronal bidimensional CT scan sections are no more necessary. The clearer perception of both the spacial relationships and delineation of these condylar fractures results in a better choice for surgical planning.

Adult↗
PubMed1995

Endotoxin and interleukin-1 related hepatic inflammatory response promotes liver failure after partial hepatectomy.

Impairment of various functions of the liver and concomitantly increased levels of parameters of liver damage, a clinical entity termed liver failure, is commonly seen after partial hepatectomy. We investigated in a rat model whether damage of the remnant liver was due to local inflammatory responses, and related to endotoxin or interleukin-1 (IL-1). To address this question, the effects of partial hepatectomy on infiltration of immunocompetent cells and expression of major histocompatibility complex (MHC) class II antigen of macrophages in the remnant liver was studied using immunohistochemical techniques. Specific intervention with recombinant N-terminal bactericidal/permeability-increasing protein (rBPI23) to neutralize endotoxin and with IL-1 receptor antagonist (IL-1ra) to block IL-1 activity was used to examine the respective roles of endotoxin and IL-1. After partial hepatectomy, we found an influx of neutrophils, an increased expression of MHC class II antigens, and morphologic changes of Kupffer cells consistent with activation. These inflammatory events coincided with increased serum levels of markers of liver damage (aspartate aminotransferase, alanine aminotransferase, ammonia). Both neutralization of endotoxin and blocking of IL-1 activity reduced hepatic inflammation and reduced serum levels of aminotransferases and ammonia. In addition, liver cell proliferation as assessed by staining for proliferating cell nuclear antigen (PCNA) expression was significantly enhanced when either endotoxin or IL-1 effects were blocked. Thus, our results suggest that local hepatic inflammatory responses inhibit liver cell proliferation and promote liver failure, presumably by affecting the functional capacity of the remnant liver.

Animals↗
PubMed1995

[Retro-duodenal papillary perforation after endoscopic sphincterotomy. Role of surgical treatment by exclusion of the duodenum. Apropos of 3 cases].

Among the complications of endoscopic sphincterotomy whose rate is about 10% of cases, the retroduodenal papillary perforation represents about 1% of cases. The diagnosis lies on radiological examination which may show during the sphincterotomy the extravasation of the contrast fluid used for the retrograde cholangiography; it can be suggested by the presence of clinical signs of retroperitoneal sepsis or peritonitis. The treatment depends on the severity or peritonitis. The treatment depends on the severity of the clinical symptomatology; it is generally a medical treatment associating nasogastric aspiration and antibiotherapy, and more rarely a surgical one. There is no consensus concerning surgical modalities. We report 3 cases of retroduodenal papillary perforation treated surgical by a duodenal exclusion aiming to transform a complex fistula in a bilio-pancreatic fistula which can be more easily managed by somatostatine-like drugs.

Aged↗
PubMed1995

[Surgical treatment of adenocarcinoma of the stomach: 1969-1994. Apropos of 261 cases].

The study concerned 261 cases of gastric adenocarcinoma operated on between 1969 and 1994. Clinical, histological and therapeutic features were analyzed and compared during 3 periods (Group 1: 1969-78, Group 2: 1979-88, Group 3: 1989-94). The aim was to evaluate changes and results occurred in gastric carcinoma. The median age was 65 years (rage 25-90 years), the sex ratio, 1.9. The most common location was in the lower third of the stomach and the cancer was often far-advanced (73 percent of stages III and IV). Subtotal gastrectomy was replaced by total gastrectomy; the number of distal gastrectomy was unchanged. Large lymph node dissection was systematically performed in group 3. Curative resection rate increased from 28 to 51 percent between group 1 and group 3. Despite the more radical surgery, morbidity and post operative mortality rates decreased (respectively: 44.5%, 33%, 25.4%, and 22%, 10%, 7.2% for the groups 1, 2, 3, p < 0.01). 2-year survival rates were 20 percent for group 1, 25 percent for group 2 and 32 percent for group 3 (p < 0.01). This rates can be considered as satisfying in view of the high rate of III and IV stages.

Adenocarcinoma↗
PubMed1995

[Does the choice of mammoplasty pedicle influence the shape of reduced the reduced-sized breast?].

Thirty seven patients with breast hypertrophy were restrospectively reviewed with a mean follow-up of 2 years. Reduction mammoplasty was performed with 3 different pedicles (superior, inferior and both) involving a glandular resection of a least 500 g on each side in all cases. The results were evaluated according to both objective and subjective criteria. The choice of pedicle had a considerable influence on the results. The vertical limb usually increased with time (months), although its intraoperative length was 5 cm. The increasing length of the vertical limb varies according to the type of pedicle chosen. The mean length increase was 1.52 cm; 4.18 cm; 4.15 cm for superior, inferior, and both pedicles respectively. The different increase was statistically significant (p < 0.001) when the technic involving a superior pedicle was compared to a technic involving an inferior pedicle. No statistically significant difference was observed between technics using the inferior and both pedicles. A superior pedicle technic entails the lowest increase of the vertical limb length which in turns leads to better long-term cosmetic results.

Adult↗
PubMed1995

Haemophilia A: mutation type determines risk of inhibitor formation.

The formation of factor VIII antibodies is a major problem for replacement therapy of haemophilia A patients. Antibodies occur in 5-30% of patients with severe haemophilia A. The reason for antibody formation is still unknown. In this study we correlate for the first time different factor VIII gene mutations, stop- and missense mutations, large and small deletions and intrachromosomal intron 22 recombinations to antibody formation. A total of 364 patients with known inhibitor status of our institute, of the database, and of 3 studies representing intron-22-inversion data are included. The results show that the risk for developing factor VIII antibodies is strongly related to stop mutations. large deletions and intrachromosomal recombinations. A probable explanation could be the complete lack of endogenous circulating factor VIII protein in these cases. Other factors that might be important for the pathogenesis of inhibitor formation, e. g. the antenatal period, as well as possible therapeutic effects, are discussed.

Antibodies↗
PubMed1995

[True benign non-parasitic cysts of the spleen: from diagnosis to treatment. Apropos of 5 new cases].

True non parasitary splenic cysts are uncommon. They are characterized histological by an epithelium on the inner surface of the cyst wall. This study presents, about 5 new cases of splenic cysts, the clinical presentation, the difficulties of the diagnosis based on the ultrasound exploration and computed tomography scan investigation, and the different possibilities of management of these cysts. The principal of the treatment is the resection of the totality of a cyst with a diameter higher than 5 cm. A partial splenectomy seems to be the best treatment, whenever possible, especially in children.

Adolescent↗
PubMed1994

Partitioning of high-density lipoproteins in charge-sensitive two-phase systems.

Aqueous polymer two-phase systems characterized by a difference in the electrical potential between the upper and the lower phase (charged systems) are useful tools for the detection of changes in the surface charge and hydrophobicity of high-density lipoproteins (HDL). While the large particle size of low-density lipoproteins (LDL) leads to accumulation at the interface, the smaller diameter and the higher surface charge density of the native HDL particles allows partitioning without aggregation at the interface. Charged two-phase systems can be used to check the native state of HDL samples. Moreover, these systems would be suitable for investigating the hydrophobicity and surface charge of modified HDL.

Dextrans↗
PubMed1994

Delta-opioid receptor agonists inhibit neuromuscular transmission in human colon.

The present study was undertaken to investigate the possible role of delta-opioid receptors in the neuroregulation of human colonic motility by using a superfusion model. Spontaneous mechanical activity and responses to electrical transmural nerve stimulation of both longitudinal and circular muscle strips from the human sigmoid colon were studied. Exogenously added delta-opioid receptor agonists did not modify spontaneous contractile activities of either type of strip. Nerve stimulation induced a triphasic response composed of an initial contraction followed by a relaxation and an off-contraction. This response was mediated by cholinergic excitatory nerves and non-adrenergic, non-cholinergic excitatory and inhibitory nerves. [Met5]Enkephalin and the synthetic delta-opioid receptor agonist [D-Pen2,D-Pen5]enkephalin (DPDPE) significantly decreased the amplitude of the initial contraction and of the off-contraction. The effects of both delta-opioid receptor agonists were reduced in the presence of either the delta-opioid receptor antagonist, ICI 174864, or another delta-opioid receptor antagonist, naltrindole. ICI 174864 prevented neither the effects of a natural kappa-opioid receptor agonist, dynorphin-(1-13) nor those of the mu-opioid receptor agonist, PL017. Therefore, these data suggest that delta-opioid receptors might be involved in the neuroregulation of smooth muscle of human colon and may mediate inhibition of cholinergic and non-cholinergic excitatory transmission within the myenteric plexus.

Analgesics↗
PubMed1994

A new gene expression system based on a fructose-dependent promoter from Rhodobacter capsulatus.

Translational lacZ fusions were constructed to analyse transcription of the fructose operon, encoding the fructose-specific phosphotransferase system of Rhodobacter capsulatus. It was demonstrated that transcription from the fru promoter (fruP) was negligible without fructose, and stimulated more than 100-fold by the presence of the inducer. A multiple cloning site, fruP, and a cassette conferring gentamycin resistance were assembled to form a cloning cartridge which is easily transferable to a broad-host-range vector. The sequence initiating the first gene of the fru operon was altered to introduce a NdeI site, allowing insertion of the 5' end of a gene at the correct distance from the ribosome-binding site. The system has been used to express the Escherichia coli lacZ gene in R. capsulatus. beta Gal activity was shown to be specifically and rapidly induced by fructose, at low concentrations. Vectors for fructose-dependent gene expression also proved to be useful in the complementation analysis of mutants. A fdxN mutant of R. capsulatus, markedly impaired in its ability to fix nitrogen due to the lack of a ferredoxin, could be fully complemented using a plasmid carrying a copy of fdxN behind fruP. Complementation, as well as the synthesis of the ferredoxin, were found to be strictly fructose dependent.

Base Sequence↗