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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 271 records · Page 15Linked to original sources
PubMed1997

Human kidney free fatty acid and glucose uptake: evidence for a renal glucose-fatty acid cycle.

To determine the relationship between free fatty acids (FFA) and glucose uptake by the human kidney, 12 postabsorptive normal volunteers underwent renal vein catheterization and were infused to isotopic steady state with [6-3H]glucose and [9,10-3H]palmitate. Arterial and renal vein palmitate specific activities were not significantly different (3,533 +/- 219 vs. 3,549 +/- 220 dpm/mumol, P = 0.64). Palmitate renal fractional extraction and uptake determined isotopically (7.2 +/- 1.1% and 9.1 +/- 1.4 mumol/min) were not significantly different from those calculated by net balance measurements (8.3 +/- 1.2% and 9.7 +/- 1.2 mumol/min, P > 0.07 and P > 0.7, respectively). Renal palmitate uptake accounted for 8.7 +/- 1.3% of its systemic turnover. Renal linoleate and oleate fractional extraction calculated by net balance measurements (8.0 +/- 0.9 and 7.7 +/- 1.2%, respectively) were not significantly different from each other and that of palmitate (all P > 0.7). Renal uptake of palmitate, linoleate (7.9 +/- 1.0 mumol/min), and oleate (10.9 +/- 2.0 mumol/min) were all directly proportional to their arterial concentrations (r = 0.70, 0.68, and 0.63, respectively, all P < 0.025). Renal glucose uptake (93 +/- 10 mumol/min) accounted for 12.6 +/- 1.5% of its systemic turnover and was inversely related to the sum of palmitate, linoleate, and oleate uptake (r = -0.74, P < 0.01). These data indicate that in postabsorptive humans: 1) the kidney is an important site of FFA and glucose disposal, 2) a renal glucose-fatty acid cycle may exist, and 3) there appears to be little or no release into the circulation of stored renal FFA.

Adult↗
PubMed1997

Role of the kidney in human leptin metabolism.

To assess the role of the human kidney in leptin metabolism, we measured renal leptin net balance and urinary leptin excretion in 16 normal postabsorptive volunteers with varying degrees of obesity. Arterial leptin concentrations (11.6 +/- 2.7 ng/ml) significantly exceeded renal vein concentrations (10.3 +/- 2.5 ng/ml, P < 0.001). Renal leptin fractional extraction averaged 13.1 +/- 1.1%, and renal leptin net balance (uptake) averaged 1,070 +/- 253 ng/min. Lineweaver-Burk analysis indicated that renal leptin uptake followed saturation kinetics with an apparent Michaelis-Menten constant of 10.9 ng/ml and maximal velocity of 1,730 ng/min. Leptin was generally undetectable in urine. Using literature values for systemic leptin clearance, we calculated that renal leptin uptake could account for approximately 80% of all leptin removal from plasma. These data indicate that the human kidney plays a substantial role in leptin removal from plasma by taking up and degrading the peptide.

Adult↗
PubMed1997

Characterization of progesterone membrane binding sites from porcine liver probed with a novel azido-progesterone radioligand.

A new derivative of progesterone was synthesized for photoaffinity labelling of specific binding sites in porcine liver microsomes. Using progesterone-3-(O-carboxymethyl)-oximino-(3-125I-iodo-4-azidosa licylamidobutylamine) as a photoactivatable radioligand, selective covalent labelling of proteins was detected in porcine liver microsomes at apparent molecular weights of 90-100 kDa and 60-65 kDa by SDS-PAGE and subsequent radioautography. These proteins showed different ligand specifity for various steroids tested. On blue native polyacrylamide-gels three selectively labelled proteins were found corresponding to apparent molecular weights of approximately 310 kDa, approximately 215 kDa and approximately 75 kDa, respectively. Using two-dimensional electrophoresis for the analysis of these protein complexes, the 215 kDa-band could be correlated to the 90-100 kDa-band, while the 75 kDa-band may correspond to the 60-65 kDa-band at one-dimensional SDS-PAGE, respectively. One or more of these proteins may be involved in the rapid progesterone-induced increase of intracellular Ca2+ described previously in cultured hepatic cells.

Affinity Labels↗
PubMed1997

[An original case of simultaneous cardiac, pancreatic and renal transplantation. Results over 6 years].

Combined transplantation is actually performed on specific and rare indications. We are presenting here the results of a combined heart-kidney and pancreatic graft. It was performed in a patient presenting an idiopathic cardiomyopathy in end-stage failure and a post-diabetic nephropathy on dialysis. Today, organs function is quite satisfactory with a 6 year follow-up. Only one isolated heart rejection episode was observed at the 15th post-operative day. The patient has recovered a full-time professional activity at one year. This successful graft was obtained by an "homogeneous multiorgan approach" during all the pre-peri and postoperative time.

Adult↗
PubMed1997

Cell-mediated immunity after pertussis vaccination and after natural infection.

The aim of this study was the investigation of the specific cell-mediated (CMI) responses induced by DTaP and to compare these data to immunity after natural infection. The ability of peripheral blood T-lymphocytes to respond to the pertussis related antigens pertussis-toxin (PT), filamentous haemagglutinin (FHA), and Pertactin (PRN) was investigated in 40 children before vaccination and at different times after vaccination with DTaP (Infanrix) by measurement of antigen-specific proliferation, lymphocyte phenotype, cytokine production and expression of activation markers (CD25, HLADR). Similar investigations were performed in children 4-6 weeks after recovery from natural pertussis. DTaP created a specific T-cell-response to PT, FHA and PRN that increased continually, depending on the progress of the vaccination schedule. In contrast to waning antibody titres, CMI was stable even between the post-basic vaccination and the pre-booster period. The magnitude of CMI after DTaP equalled those after natural infection. Measurement of cytokine-pattern showed induction of IFN-tau-producing T-helper-1-cells with lower stimulation of IL 10-producing T-helper-2-cells for DTaP and natural infection. Our data indicate that DTaP-vaccination induces a potent immune response to PT, FHA, and PRN at least equivalent to CMI after natural infection. The finding of a preferential T-helper-1-induction after DTaP and natural infection suggests a role of IFN gamma-activated macrophages in the protective response against B. pertussis-induced disease.

Adhesins, Bacterial↗
PubMed1997

[Acute pancreatitis and ectopic pancreas].

We report the case of a 28-year-old woman with a pancreatic heterotopia presenting with a history of acute pancreatitis. Symptoms were epigastric pains. Abdomino-pelvic CT Scan revealed a tumor located in gastro-duodenal area. Exploratory surgery was performed, and the segment containing the mass was resected. Histopathologic examination of the lesion revealed heterotopic pancreatic tissue without malignancy.

Acute Disease↗
PubMed1997

[Osteosynthesis of subcondylar fractures using a rectangular 3-dimensional stabilization plate].

The current international opinion for the treatment of displaced subcondylar fractures has become more aggressive after the rediscovery of the submandibular incision and the creation of new fixation material. We report 19 patients with displaced subcondylar fractures who were treated with reinforced rectangular plates. The pure titanium plates are slightly concave and measure 13 by 9 mm. We evaluated dental articulation, mouth opening, propulsion and duction and observed rapid recovery of mandibular kinetics and mandibular function. Use of this plate is a major progress in the treatment of fractures of the condyle.

Biocompatible Materials↗
PubMed1997

[Value of absorbable clips in laparoscopic cholecystectomy. A randomized prospective study].

Most surgeons use metal clips in laparoscopic cholecystectomy. The aim of this prospective randomized controlled study was to evaluate the efficacy of absorbable clips in elective laparoscopic cholecystectomy. One hundred consecutive patients with symptomatic gallstones without complications were randomized into groups; group T had two metal clips (titan clip ETHICONR), group R (laproclipR Davis and Geck) had one absorbable clip applied on the cystic duct and cystic artery. The patients were followed for one year. There was no difference between the two groups concerning operative time, hospital stay and postoperative complications. The absorbable clips seem to be as effective as metal clips in providing hemostasis in cystic artery and in cystic duct ligation.

Adult↗
PubMed1997

[Outcome of surgical treatment of cancer of the stomach. Report of 330 cases].

The study concerned 330 cases of gastric adenocarcinoma operated from January 1969 to June 1996. Clinical, histological and therapeutic features were analyzed and compared during 3 periods (Group 1: 1969-79, Group 2: 1979-88, Group 3: 1989-96). The aim was to evaluate changes and results occurred in gastric carcinoma. The median age was 65 +/- 11 year (range 25-90), the sex ratio 2. The most common location was in the lower third of the stomach and the cancer was often far advanced (71 percent of stages III and IV). Subtotal gastrectomy was replaced by total gastrectomy and large lymph node dissection was systematically performed in group 3. Curative resection rate increased from 28 to 60 percent between group 1 and group 3. Despite the more radical surgery, post-operative mortality rates decreased respectively 22%, 9%, 8% for the groups 1, 2, 3 (p < 0.01) and global morbidity remained stable while the rate of intra-abdominal infection have changed in group 3 (4.8% vs 2.7% and 2.1% in respectively groups 1 and 2; p = ns). Two year survival rates were 20% for group 1.25% for group 2 and 35% for group 3 (p < 0.01). This results can be considered as encouraging but have to be confirmed at 5 year survival.

Adenocarcinoma↗
PubMed1997

[The value of peroperative colonic lavage in urgent colonic surgery. Apropos of 54 patients].

UNLABELLED: The effects of on-table colonic irrigation followed by primary large bowel resection and anastomosis for emergency left colonic disease were prospectively studied in 54 patients. PATIENTS AND METHODS: Eighteen patients had a diverticular sigmoiditis complicated by localized (8) or generalized (4) peritonitis, 6 presented a complete sigmoid obstruction. Thirty six patients had a left colonic occlusive (33) or perforated (3) cancer. Anterograde colonic irrigation was carried out with a mean volume of 7.7 l. All patients received a double or triple antibiotic combination. The anastomosis was handsewn in 33 cases and stapled (Knight-Griffen) in 21. Seven patients with severe peritonitis had a proximal transitory stoma which was closed within 4 months. RESULTS: Two patients (3.7%) died postoperatively, one for anastomotic dehiscence and the second for evisceration. We observed 7 cases of hypothermia (< 34 degrees C) during the irrigation. Six patients developed a sepsis of the surgical wound, 2 a septicemia and l an abscess in the right iliac fossa which was percutaneously drained. All complications had a favourable outcome. CONCLUSION: This study confirms that in selected cases a single stage surgery for colonic emergencies preceded by on-table irrigation grants good results and is a safe and effective alternative to Hartmann's procedure.

Aged↗
PubMed1996

Full-length cDNA sequence of a progesterone membrane-binding protein from porcine vascular smooth muscle cells.

A full-length cDNA clone for a progesterone membrane binding protein from porcine vascular smooth muscle cells was isolated and the complete nucleotide sequence determined. The cDNA encodes a protein of 194 amino acids with a transmembrane segment. This protein is likely to represent the first steroid membrane receptor or a part of it for which sequence information is available.

Amino Acid Sequence↗
PubMed1996

Effects of midline and lateral cerebellar lesions on motor coordination and spatial orientation.

Rats were lesioned in the midline cerebellum, comprising the vermis and fastigial nucleus, or the lateral cerebellum, comprising the cerebellar hemispheres and dentate nucleus, and evaluated in a series of motor and non-motor learning tests. Rats with midline lesions had difficulty in maintaining their equilibrium on a bridge and were slower before turning upward and traversed less squares on an inclined grid. They were not impaired for muscle strength when suspended from a horizontal wire. Rats with lateral lesions had milder deficits on the bridge and were not affected in the other two tests. In the Morris water maze test, rats with lateral lesions were deficient in spatial orientation, whereas rats with midline lesions were deficient in visuomotor coordination. Lateral lesions had no effects on visual discrimination learning. These results illustrate the differential influence of midline as opposed to lateral cerebellar regions on both motor and non-motor behaviors. Fastigial nucleus lesions decreased the time spent in equilibrium and latencies before falling on the bridge and the distance travelled along the inclined grid but had no effect on muscle strength when suspended from the horizontal string. Quadrant entries and escape latencies were higher in rats with fastigial lesions during the hidden platform condition of the Morris water maze but not during the visible platform condition. It is concluded that fastigial-lesioned rats are impaired in equilibrium and spatial orientation but with repeated trials learn to improve their performances.

Analysis of Variance↗
PubMed1996

Purification and partial sequencing of high-affinity progesterone-binding site(s) from porcine liver membranes.

High-affinity progesterone-binding sites have been identified, characterized in and purified from porcine liver membranes. They were functionally solubilized by the non-denaturing zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (Chaps, 20 mM. detergent/protein mass ratio 4:1) at a yield of 75-80%. Using [3H]progesterone as radioligand, binding studies showed high-affinity and low-affinity binding sites in microsomal preparations with an apparent Kd2 of 11 nM and an apparent Kd2 of 286 nM. In solubilized fractions the high-affinity binding sites were present at an apparent Kd2 of 69 nM. In both preparations, progesterone binding was time-dependent, saturable, reversible, and showed a similar hierachy of affinities for related steroids. A purification scheme was developed based on anion-exchanger procedures. The purified fraction as identified by maximum specific progester-one-binding activity contained two major polypeptides of apparent molecular masses (SDS/PAGE) of 28 kDa and 56 kDa, respectively. Sequencing of both polypeptides showed an identical amino terminus without significant identity in the amino acid sequence to any known protein primary structure.

Amino Acid Sequence↗
PubMed1996

Identification of residues of Rhodobacter capsulatus ferredoxin I important for its interaction with nitrogenase.

In Rhodobacter capsulatus, ferredoxin I (FdI) serves as natural electron donor to nitrogenase. In order to probe amino acid residues possibly involved in the interaction with dinitrogenase reductase, FdI was subjected to site-specific mutagenesis. A three-dimensional structure of FdI was designed by computer modelling and used for selecting target residues. Mutant ferredoxins bearing substitutions of surface residues, as well as a variant having a Met2 --> Tyr replacement in the vicinity of one cluster, have been constructed. All FdI variants were expressed to similar levels both in Escherichia coli and in a FdI-deleted mutant of the natural host. Once purified, the mutant ferredoxins exhibited molecular and spectroscopic properties almost identical to wild-type FdI. Determination of the reduction potential of FdI by cyclic voltammetry gave an E'o of -510 mV (pH 7.6) for both clusters, which is one of the lowest values reported for a 2[4Fe-4S] ferredoxin. Only the [Tyr2]FdI variant showed a significant difference in redox potential (delta E'o = -15 mV). Based on in vitro assays, a [Glu27, Glu28]FdI double mutant exhibited a twofold decrease in the electron transfer rate to dinitrogenase reductase while the affinity of this mutant for the enzyme was barely affected. On the other hand, an Asp36 --> His substitution resulted in a sevenfold increase of the apparent Km for dinitrogenase reductase. Unlike FdI and the other mutant ferredoxins, the [His36]FdI variant also failed to form a cross-linked complex with dinitrogenase reductase upon incubation with a carbodiimide. It is concluded that Asp36 in FdI probably participates in the interaction between the two protein partners. Nevertheless, all the FdI mutants proved competent in restoring a wild-type phenotype when expressed in a FdI-deleted mutant background, indicating that none of the studied residues was absolutely critical for electron transfer to nitrogenase.

Amino Acid Sequence↗
PubMed1996

Biotin-labelled and photoactivatable aldosterone and progesterone derivatives as ligands for affinity chromatography, fluorescence immunoassays and photoaffinity labelling.

New derivatives of progesterone and aldosterone were synthesized and functionally tested with commercially available antibodies. The covalent labelling of antibodies specific for aldosterone and progesterone was detected by SDS/PAGE analysis and subsequent autoradiography after using 3-(O-carboxymethyl)-oximino-(3-[125I]iodo-4-azidosalicylamidobu tylamine) derivatives of aldosterone and progesterone, respectively, as photoactivatable radioligands. Labelling was not observed in the presence of an excess of the unlabelled steroid. Aldosterone was labelled with biotin and used as a tracer in a time-resolved fluorescence immunoassay. The nonradioactive tracer is highly selective for its antibody-binding site, with almost no detectable cross-reactivity for other steroids. Biotin-labelled progesterone was immobilized by avidin-agarose and used for affinity chromatography. This yielded a more than 20-fold enrichment of an anti-progesterone polyclonal antibody. These results demonstrate that derivatives of steroids are particularly useful for the development of nonradioactive assays for the determination of natural steroids and may be also useful for the detection of specific binding sites in biological material such as plasma membranes.

Affinity Labels↗