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C Hamel

Publications and source records attributed to C Hamel.

At least 37 records · Page 2Linked to original sources
PubMed1997

The protein truncation test (PTT) as a method of detection for choroideremia mutations.

The predominance of truncative mutations responsible for choroideremia (CHM) led us to investigate the use of the protein truncation test (PTT) applied to lymphocyte RNA derived from affected males as a scanning method. The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analysed by PTT after in vitro transcription/ translation. This strategy enabled us to detect the CHM-causative alteration in each of the four unrelated patients from southern France who were investigated. We describe three novel mutations (E177X, 323delT, 1313delTC), and report one recurrent mutation (R267X) in CHM. We believe this to be the first attempt at applying RT-PCR-PTT to CHM mutation detection.

Choroideremia↗
PubMed1997

Ileocecal segment transposition does not alter whole gut transit in humans.

OBJECTIVES: We have recently described a reservoir for rectal replacement after total mesorectal excision for rectal carcinoma. The ileocecal segment with its intact extrinsic nerve and blood supply is placed between the ascending colon and the anal canal. This reconstruction has been shown to provide good defecation quality and anorectal function. Whether gastric emptying and small as well as large bowel transit are affected by this transposition remains unclear. Our aim was to quantify whole gut transit in such patients and compare it with that of a matched group of controls. METHODS: Gastric emptying rates and small intestinal and colonic transit times were assessed scintigraphically in 12 patients aged 46 to 87 years with ileocecal reservoir reconstruction after total mesorectal excision and compared to a sex-matched group of asymptomatic healthy volunteers of similar age. Gastric emptying rates and small intestinal and colonic transit times were calculated as described previously. Data were compared using Wilcoxon's signed rank test for gastric emptying rates and small bowel transit or by analysis of variance for colonic transit; p < 0.05 was considered significant. RESULTS: Gastric time for half of the meal (T50) was 161 +/- 16 minutes for patients and 201 +/- 22 for the controls. Small bowel transit time was 150 +/- 15 minutes for patients and 177 +/- 22 for the controls. Geometric center at 6 hours was 1.53 +/- 0.13 for patients and 1.27 +/- 0.16 for the controls. Geometric center at 24 hours was 2.96 +/- 0.23 for patients and 2.57 +/- 0.25 for the controls. Data are mean +/- SEM. SUMMARY: Gastric emptying rates and small bowel transit and colonic transit times (expressed as geometric center at 6 and 24 hours) were similar in patients with ileocecal reservoir reconstruction and in a sex- and age-matched group of healthy controls. We conclude that the transposition of an ileocecal segment with intact extrinsic neurovascular supply between the sigmoid colon and the anal canal does not alter whole gut transit, not even in any of the presumably key regions.

Age Factors↗
PubMed1997

A complex allele (1064delTC and IVS2 + 22ins7) in the peripherin/RDS gene in retinitis pigmentosa with macular dystrophy.

Because mutations in the peripherin/RDS gene have been found in retinal dystrophies involving the macula, we examined various types of macular dystrophies from southern France to characterize sequence variations that may be associated with these conditions. DNA sequence analysis of the full coding and flanking regions of the peripherin/RDS gene was performed in fifteen unrelated patients with different types of macular dystrophy, including nine with retinitis pigmentosa (RP). Of the 15 probands with macular disease, two (13.3%) were found to carry a mutation in the peripherin/RDS gene. The recurrent mutation P216S was identified in a pedigree with autosomal dominant RP. A previously unreported complex allele (1064delTC associated with IVS2 + 22ins7) that is predicted to result in the premature termination of peripherin/RDS synthesis was identified in a sporadic case of macular atrophy with RP. We also report eight novel neutral sequence variations in the peripherin/RDS gene, most of them found in the 3' untranslated part of the gene.

Adult↗
PubMed1997

An exonic polymorphism (381A/G) in the choroideremia gene.

By using the single strand conformational analysis (SSCA) to search for point mutations in the choroideremia gene, we have identified a previously undescribed polymorphism within exon 5a (381A/G). We have studied the frequency of this polymorphism in a population from Southern France. The sequence variation creates a new restriction site for HhaI, allowing a convenient DNA-based genetic counseling in families in which the causal disease mutation is unknown.

Choroideremia↗
PubMed1997

Ileocecal interposition--functional outcome.

Surgery of rectal cancer aims at providing satisfactory quality of life early postoperatively. Low postoperative morbidity and good defecation quality early after rectal reconstruction by means of a reservoir construction are essential conditions for a good quality of life. The clinical results show, that the ileocecal interposition is feasible with a low morbidity and that the majority of patients experience good to excellent defecation quality.

Aged↗
PubMed1997

[Rapid genetic diagnosis of females carriers related to patients with choroideremia].

PURPOSE: By using the single strand conformation analysis to search for point mutations in the choroideremia gene, we had previously identified the first truncative mutation responsible for CHM in France. The aim of the present study was to perform a simple and nonisotopic routine test to identify carriers and non carriers in the relevant family. METHODS: We used a PCR-based restriction analysis to detect the presence or absence of the mutation in the family members, as the mutation creates a restriction site in the coding sequence of the CHM gene. RESULTS: We could follow the segregation of the mutation in the pedigree, and unambiguously determine the genetic status of the females. CONCLUSION: When a mutation responsible for choroideremia modifies a restriction site, the PCR-restriction provides an efficient and unexpensive one-day test to detect heterozygosity in the family.

Carrier State↗
PubMed1996

Activation of 5-hydroxytryptamine4 receptors causes calcium influx in adrenocortical cells: involvement of calcium in 5-hydroxytryptamine-induced steroid secretion.

5-Hydroxytryptamine (5-HT) stimulates corticosteroid secretion from adrenal cells through activation of 5-HT4 receptors positively coupled to adenylyl-cyclase. In the present study, we investigated in frog adrenocortical cells the effect of 5-HT4 receptor agonists on cytosolic calcium concentration ([Ca2+]i) and determined the sequence of events associated with 5-HT4 receptor agonist zacopride (10[-8] to 10[-5]M each in the vicinity of cultured adrenocortical cells caused a dose-dependent increase in [Ca2+]i. Preincubation of the cells with the selective 5-HT4 receptor antagonist [1-[2-(methylsulfonylamino)ethyl]-4- piperidinyl]methyl-1-methyl-1H-indole-3-carboxylate maleate totally blocked the 5-HT-induced stimulation of [Ca2+]i. Chelation of extracellular calcium with ethylene glycol bis (beta-aminoethyl ether)-N,N,N', N'-tetraacetic acid (10 MM) suppressed the stimulatory effect of 5-HT on [Ca2+]i. Conversely, thapsigargin, an inhibitor of calcium ATPase activity, had no effect on the [Ca2+]i rise. The calcium influx induced by 5-HT4 receptor agonists was not affected by nifedipine and omega-conotoxin GVIA but was totally blocked by pimozide, a T-type calcium channel antagonist. The [Ca2+]i response to zacopride was potentiated by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine and markedly reduced by the protein kinase A inhibitor adenosine-3',5'-cyclic monophosphorothioate. We studied in perifused frog adrenal slices the involvement of [Ca2+]i rise and cAMP formation in the mechanism of action of 5-HT4 receptor agonists. Zacopride-induced steroidogenesis was significantly reduced in the presence of adenosine-3'5'-cyclic monophosphorothioate or after suppression of calcium in the perifusion medium. The stimulatory effect of zacopride on corticosteroid secretion was not affected by nifedipine and omega-conotoxin GVIA but was significantly inhibited by pimozide. Taken together, these data indicate that activation of 5-HT4 receptors in adrenocortical cells causes stimulation of adenylyl cyclase and subsequently increases calcium influx through a T-type calcium channel. Both the increased in cAMP formation and the calcium rise are involved in the stimulatory effect of 5-HT on corticosteroid secretion.

Adrenal Cortex↗
PubMed1994

Effect of a series of 5-HT4 receptor agonists and antagonists on steroid secretion by the adrenal gland in vitro.

We have previously shown that serotonin (5-hydroxytryptamine, 5-HT) stimulate corticosterone and aldosterone secretion from perifused frog adrenal gland in vitro through activation of 5-HT4 receptors. In the present study, we have used this model to investigate the effect of newly discovered 5-HT4 receptor agonists and antagonists on corticosteroid secretion. Serotonin, the benzamide derivatives (R,S)-zacopride ((R,S)-4-amino-N-(1- azabicyclo[2.2.2]oct-3-yl)-5-chloro-2-methoxybenzamide, HCI) and its enantiomers, the azabicycloalkyl benzimidazole derivatives BIMU 1 (endo-N- (8-methyl-8-azabicyclo-[3.2.1]oct-3-yl)-2,3-dihydro-3-ethyl-2-oxo- 1H-benzimidazole-1-carboxamide, HCl) and BIMU 8 (endo-N-(8-methyl-8- azabicyclo-[3.2.1]oct-3-yl)-2,3-dihydro-(1-methyl)ethyl-2-oxo-1H- benzimidazole-1-carboxamide, HCl) were all capable of enhancing corticosterone and aldosterone secretion in a dose-dependent manner. Serotonin was the most potent stimulator of steroidogenesis (EC50 = 1.5 x 10(-7) M) while the potency of the benzamide and the benzimidazolone derivatives was approximately 10 times lower. The rank order of efficacy of the different 5-HT4 receptor agonists was: (S)-zacopride > BIMU 8 = (R,S)-zacopride > BIMU 1 = (R)-zacopride = 5-HT. The stimulatory effects of 5-HT and the benzimidazolone derivatives on corticosteroid secretion were not additive, suggesting that they activated the same receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1989

Development and characterization of monoclonal antibodies directed against the retinal pigment epithelial cell.

The retinal pigment epithelium consists of a unicellular layer of neuroepithelial cells that are essential for the maintenance of normal function of the neural retina. In order to evaluate more critically this cell in health and disease, we prepared monoclonal antibodies against human retinal pigment epithelial (RPE) cells. Balb/c mice were immunized with human RPE cells. Spleen cells were fused with myeloma cells and resultant hybridomas were selected for antibody production. Supernatants were assayed by immunoperoxidase on frozen sections of human eye tissues. Two hybrids were cloned and ascites were generated in mice. These IgG antibodies react only with RPE cells and show no cross-reactivity with other cells in the eye or with human brain, kidney, skin, salivary glands, lymphocytes or monocytes. These antibodies recognize cell surface molecules that are highly conserved since they can be found in man, monkey, rat, cow, chicken and frog. SDS gel electrophoresis and immunoblot analysis showed that one of the antibodies reacted with a 42,000 MW polypeptide. Evaluation of the developing rat retina revealed that the epitopes are not detected at birth, are weakly present at day 6 and are highly recognized by day 9. These immunoglobulins will allow us to evaluate RPE cells in disease (proliferation, migration) and to probe the bioregulatory functions (phagocytosis, vitamin A transport) of these cells.

Animals↗
PubMed1988

[A misunderstood treatment for hyperhidrosis: ionization. Principles, material, methodology, early results].

Based on a new and specific apparatus developed by one of the authors, an original method of treatment of palmoplantar hyperhidrosis, either essential or associated with acrocyanosis, is described in detail. The extremities to be treated are placed in tanks containing tap water ensuring conduction fo current between epidermis and electrode. The recommended current of 20 milli-amperes is obtained by adjustment of a potentiometer. Treatment sessions (20 minutes for hands or feet, 40 for all four extremities) take place with a well defined frequency: 3 the first week, 2 the second, I the following two weeks. Maintenance sessions are necessary when sweating recurs. In a longitudinal series of 29 patients, 28 (96.5%) were significantly improved. From the 5th session onwards, the decrease in hyperhidrosis was evaluated by patients as very pronounced in 5 cases (17.2%) and as complete in 21 cases (72.5%). In 5 of the 6 patients with hyperhidrosis associated with acrocyanosis, the patients reported attenuation of cyanotic coloration of skin and relative warming up of extremities treated. Tolerance was excellent in 28 cases, incidents being rare and minor. Patients with pacemakers cannot be treated by this method.

Adolescent↗
PubMed1987

Treatment of bilateral spontaneous dural carotid-cavernous fistulas by coils and sclerotherapy. Case report.

A case of bilateral spontaneous carotid-cavernous fistulas producing increased intraocular pressure is reported. The fistulas lay between the meningeal branches of the internal carotid artery (ICA) and the cavernous sinus, but the ICA itself was not involved. Successful treatment was accomplished by the introduction of steel coils and a sclerotic liquid into the cavernous sinus via the distal superior ophthalmic vein.

Arteriovenous Fistula↗