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G Sicard

Publications and source records attributed to G Sicard.

29 records · Page 2Linked to original sources
PubMed1989

A comparative study of 2-deoxyglucose patterns of glomerular activation in the olfactory bulbs of C57 BL/6J and AKR/J mice.

We have studied the patterns of glomerular activation evoked in the olfactory bulbs of C57BL/6J and AKR/J mice by olfactory stimulations with amyl acetate or isovaleric acid. Patterns of glomerular activation were obtained with the 2-deoxyglucose method and subsequently compared using a computer-assisted image analysis. The mice of both inbred strains stimulated with amyl acetate or isovaleric acid were characterized by areas of high 2-deoxyglucose uptake in their glomerular layer. Statistical comparisons of the patterns demonstrated that they were odor-specific. Although C57BL/6J mice have been found to be specifically anosmic to isovaleric acid, our findings indicate that their olfactory system is topographically activated by olfactory stimulations with this odorant. However, patterns of glomerular activity evoked by isovaleric acid stimulations are not similar in the two studied strains.

Action Potentials↗
PubMed1989

Thromboxane synthesis inhibition and renal allograft function.

These data indicate that chronic administration of CGS-12970 to renal allograft recipients maintains renal allograft function. These effects are probably due to selective inhibition of local tissue TXA2 production. These data also suggest that elevations in renal allograft tissue prostacyclin production may be secondary to ischemia since improving renal blood flow and GFR with selective thromboxane synthesis inhibitors leads to normalization of renal prostacyclin synthesis. The possible utility of using CGS-12970 as an adjunct therapy in human renal allotransplantation should be strongly considered.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Specificity of spatial patterns of glomerular activation in the mouse olfactory bulb: computer-assisted image analysis of 2-deoxyglucose autoradiograms.

We have developed a computer-assisted method for analyzing the 2-deoxyglucose (2-DG) autoradiograms of mice olfactory bulbs. The purpose of the study was to numerize the maps of glomerular activation in order to achieve a statistical comparison of the glomerular patterns evoked by different stimuli. The spatial distribution of glomerular activation was displayed on unfolded representations of the glomerular layer which were built up using glomerular optical densities (OD) measured systematically within 13 sections per bulb. Each bulbar sample was converted into an 'OD profile'. A matrix composed of 18 OD profiles was submitted to a principal component analysis. The first factor which accounted for 28% of the variance separated unambiguously two clusters corresponding to the bulbs issued from animals stimulated with amylacetate and isovaleric acid, respectively. The second and third factors which accounted for 14% and 12% of the variance segregated the control group (animals exposed to pure air) from the odor-stimulated ones. It was demonstrated that the cluster separation was actually due to the specific spatial distribution of the most-labelled glomeruli. A particular attention was paid to the well-delineated glomerular activation evoked by isovaleric acid. The results demonstrate the specificity and reliability of the glomerular 2-DG patterns. The method should be useful for further comparisons of patterns elicited by larger sets of odorant compounds.

Animals↗
PubMed1986

Electrophysiological recordings from olfactory receptor cells in adult mice.

A new preparation for in vivo electrophysiological recording of olfactory receptor cell activity in the mouse is described. Receptor cells were characterized by their spontaneous activity and responses to odorants. These preliminary observations suggest that the olfactory receptor cells in mouse are more selective than receptor cells of the frog olfactory epithelium.

Animals↗
PubMed1985

Olfactory discrimination of structurally related molecules: receptor cell responses to camphoraceous odorants.

Electrophysiological investigations of the selective sensitivity of receptor cells have shown that odorants could be distributed into groups according to the profiles of responses that they elicited from a population of receptor cells. As the concept of odorant group plays an important role in the understanding of olfactory coding, an attempt was made to investigate in detail the group properties of a number of structurally and qualitatively related molecules: 1,8 cineole, DL-camphor, borneol, iso-borneol, adamantane, fenchone, fenchyl alcohol, 3,3,5-tri-methyl cyclohexanone, camphene, 1,1,2,2-tetra-bromoethane. These odorants, along with several other representatives of other odorant groups, were utilized to stimulate a set of 71 individually recorded receptor cells. Factor analysis of electrophysiological data demonstrated that the grouping of odorants with camphor could be predicted on the basis of the shape and size of the molecules. The analysis also showed that even a clearly defined odorant group such as the camphor group is not likely to be determined by a single type of receptor site.

Animals↗
PubMed1984

Receptor cell responses to odorants: similarities and differences among odorants.

An extensive exploration of the discriminating properties of olfactory receptors cells has been conducted in our laboratory through the statistical processing of single cell responses recorded in the frog's olfactory epithelium. Similarities between odorant stimulating properties could be demonstrated by comparing the complex response profiles of receptor cells, resulting in the concept of odorant groups which depicts consistent relationships found between some odorous compounds. The recording technique limits the number of odorants which can be tested and compared within the same series of experiments. Thus, based upon previous studies we have chosen a specific set of 20 odorants whose characteristics are known but, up to this time, have not been compared in the same experimental system. These odorants were: acetophenone, anisole, n-butanol, DL-camphor, cyclodecanone, 1,8-cineole, p-cymene, D-citronellol, n-heptanol, isoamyl acetate, isovaleric acid, D-limonene, methyl amylketone, L-menthol, phenol, thiophenol, pyridine, thymol, cyclohexanol, cyclohexanone. The pattern of similarities between these odorants, as delineated with the aid of correlation coefficient computation, factor analysis and non-hierarchical taxonomy, confirms the reality of several odorant groups previously suggested and describes their cross-relationships. The receptor mechanisms underlying these odorant groups are discussed. Because reliable prominent features of the olfactory stimulus space can be established on an objective basis, the findings are proposed as a reference for future studies on other aspects of olfactory discrimination.

Animals↗
PubMed1981

Altered adenylate cyclase kinetics in hyperfunctioning human parathyroid glands.

Current evidence suggests that parathyroid gland adenylate cyclase is involved in the control of parathyroid hormone (PTH) secretion. Thus, the altered control of PTH release in hyperparathyroidism may relate to altered adenylate cyclase activation. Therefore, we examined adenylate cyclase kinetics in membrane preparations from hyperfunctioning human parathyroid glands and normal human and bovine parathyroid tissues. There were no differences in the affinity for ATP between enzymes of normal and pathological tissue. However, the enzyme in 10 hyperfunctioning glands showed increased affinity for Mg++. The activation constant for Mg++ (KaMg) of adenylate cyclase in normal human glands was 10.6 +/- 2 mM, a value not different from that of normal bovine parathyroid tissue (9.5 +/- 1 mM). In contrast, the adenylate cyclase in membrane preparations from three of four hyperplastic and six of seven adenomatous human glands showed a markedly reduced KaMg, ranging from 0.85-1.64 mM and from 1.58-6.46 mM, respectively. In one adenoma and one hyperplastic gland, the Ka of the enzyme for Mg++ was close to normal. The addition of guanylylimidodiphosphate or GTP to the incubation mixture increased, in a dose-dependent manner, the apparent KaMg of the enzyme in the abnormal tissue toward normal, suggesting a defective nucleotide regulatory site in the adenylate cyclase of hyperparathyroid glands. In addition, the hyperparathyroid gland enzyme was less susceptible to inhibition by calcium, requiring 0.7-1 mM Ca++ for 50% inhibition, whereas comparable inhibition of the normal adenylate cyclase was seen at 0.22-0.28 mM Ca++. We conclude that the abnormal control of PTH secretion in hyperparathyroidism may be related, at least in part, to alterations in the characteristics of parathyroid gland adenylate cyclase.

Adenosine Triphosphate↗
PubMed1981

Discrete colon ulcers as a cause of lower gastrointestinal bleeding and perforation in end-stage renal disease.

Since 1975 at our institution six cases of discrete colon ulcers have been noted in patients with end-stage renal disease. Five patients were on long-term hemodialysis, and one patient had received a cadaver kidney transplant. Four patients presented with lower gastrointestinal hemorrhage-two acute and two subacute. Two patients presented with diffuse abdominal pain and peritoneal signs. Two colon ulcers were diagnosed by colonoscopy, two were diagnosed in laparotomy, one was diagnosed by arteriography, and one ulcer was diagnosed only on pathologic examination of the resected colon. Pathologic examination disclosed idiopathic ulcers in all six cases. All patients were managed surgically. The mortality rate was 50%. Discrete colon ulcers should be considered in the differential diagnosis when the hemodialysis or kidney transplant patient presents with lower gastrointestinal bleeding or abdominal pain and peritoneal signs.

Acute Kidney Injury↗
PubMed1981

Cryptococcal pyelonephritis and disseminated cryptococcosis in a renal transplant recipient.

Symptomatic cryptococcal pyelonephritis, meningitis, and disseminated cryptococcosis are described in a renal cadaver transplant recipient who subsequently died of Klebsiella pneumoniae sepsis. The presence of cryptococcuria and a subsequent positive CSF India ink stain led to the initial diagnosis of disseminated cryptococcosis. Therapy with 0.511 g of amphotericin B and 112.5 g of flucytosine for four weeks did not eradicate Cryptococcus from the kidney and was associated with hepatotoxicity. The importance of urinary examination and culture for C neoformans is emphasized. Cryptococcal pyelonephritis should be considered in the differential diagnosis of allograft rejection in the renal transplant patient.

Cadaver↗