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Biomedical subjects

A Chiron

Publications and source records attributed to A Chiron.

12 recordsLinked to original sources
PubMed2000

Roux-en-Y limb motility after total or distal gastrectomy in symptomatic and asymptomatic patients.

BACKGROUND: The aims of this study were to compare Roux-en-Y limb motor patterns after total or distal gastrectomy, and to identify possible motor differences between symptomatic and asymptomatic patients. The usefulness of preoperative recording was also investigated. STUDY DESIGN: Sixteen patients were enrolled in the study, 10 patients after total gastrectomy (TG group) and 6 patients after distal gastrectomy (DG group). In 6 of 10 patients in the TG group, recordings were obtained before and after operation. Manometric recordings in the limb lasted 6 hours in all patients, 3 hours during fasting, and 3 hours after a 750-kcal meal. An intravenous injection of trimebutine (100-mg i.v.) was systematically administered at the end of each recording session. Motor results of the patients were compared with those obtained in the intact jejunum of 20 healthy controls. RESULTS: After operation, when patients were compared with controls, phase III (ie, regular activity of the migrating motor complex) was more frequent and more often incompletely propagated (5 of 16 patients versus 1 of 20 controls, unadjusted p < 0.05) and was significantly slower (p < 0.01 versus controls). Intravenous trimebutine induced phase III in 12 of 16 patients within a mean of 8.8 +/- 1 (SEM) minutes, longer than in controls (delay < 2 minutes). The fed pattern was shorter than in controls in both TG and DG groups, and the postprandial area under the curve during successive 30-minute periods was reduced in the DG group compared with controls (p < 0.01). In patients investigated before gastrectomy, motor parameters were not different from those of controls. Surgery resulted in an increased number of phase IIIs and a decreased migration velocity (p < 0.01) of phase III, a longer delay in response after trimebutine (p < 0.0001), and a reduced postprandial motor response (p < 0.01). After the operation, 4 of 10 patients in the TG group and 5 of 6 patients in the DG group were symptomatic. Symptomatic patients had slower and more often incompletely propagated (p < 0.01) phase III compared with asymptomatic patients. CONCLUSIONS: Roux-en-Y limb reconstruction mainly disturbs phase III propagation and the motor response to a meal. Motor changes are more marked after DG than after TG. Disturbed phase III propagation is the main difference between symptomatic and asymptomatic patients. Successful induction of phase III with trimebutine after gastrectomy and Roux-en-Y reconstruction indicates maintenance of encephalinergic mechanisms.

Anastomosis, Roux-en-Y↗
PubMed2000

High frequency in esophageal cancers of p53 alterations inactivating the regulation of genes involved in cell cycle and apoptosis.

Somatic mutations of the tumor suppressor gene p53 have been frequently detected in esophagal cancers, but their biological significance remains to be established. The tumor suppressor activity of p53 results in part from its ability to transactivate genes involved in the cell cycle and apoptosis, such as p21, bax and PIG3, and some p53 mutations may have a differential effect on the transactivation of these target genes. We developed yeast strains in which the activation by wild-type p53 of reporter plasmids containing p53 binding sites present within these target genes induces a change in the color of the colonies (red/white). Using these strains, we analyzed 56 esophageal cancers from patients residing in Normandy, France, a high incidence geographic area. Forty-seven tumors (84%), scored as mutant with the p21, bax and PIG3 reporter strains and in most of the cases (76%), the percentage of red colonies suggested that both p53 alleles were inactivated. Sequencing analysis allowed the identification of a p53 mutation in each positive sample, and the spectrum of mutations was in agreement with the etiological role of tobacco and alcohol. These results confirm the high frequency of biallelic p53 mutations in esophageal carcinoma and strongly suggest that their biological consequence is the complete alteration of the transactivation of genes involved in the cell cycle and apoptosis, which indicates that p53 alteration is a key event in esophagus carcinogenesis.

Apoptosis↗
PubMed1999

Postoperative management of stage II/III colon cancer: a decision analysis.

BACKGROUND & AIMS: Two separate decisions must be made for the management of patients with resected stage II/III colon cancer: whether to begin adjuvant chemotherapy and whether patients should be included in a follow-up protocol consisting of regular monitoring of carcinoembryonic antigen level and of colonoscopy and imaging. The standard management for these patients is adjuvant chemotherapy for stage III patients and follow-up for stage II/III patients with resected colon cancer. METHODS: Decision analysis was used to compare the effectiveness (5-year survival rate) and cost-effectiveness ratio of 7 strategies of treatment and follow-up. RESULTS: The most cost-effective strategies were adjuvant chemotherapy for all patients with stage II/III resected colon cancer, with either no follow-up or follow-up only for patients aged less than 75 years with a seric preoperative carcinoembryonic antigen level of >5 ng/mL (5-year survival, 62.3% or 62.7%; cost per surviving patient, $8254 or $8657, respectively). The order of efficacy of the strategies was insensitive to changes in the values of the studied variables. The method of follow-up does little to improve 5-year survival but adds substantial cost. CONCLUSIONS: The current standard strategy may not be the most cost-effective strategy for the management of patients with resected colon cancer.

Cohort Studies↗
PubMed1999

Formation of a conducting channel in air by self-guided femtosecond laser pulses.

We report a drastic reduction of air resistivity following the passage of a self-guided femtosecond pulse from a Ti:sapphire laser system at 800 nm with energies per pulse between 1 and 14 mJ and a pulse duration of 120 fs. Connected plasma filaments with a length that can exceed 150 cm are created by these pulses. The presence of a conducting plasma channel results from multiphoton ionization of air molecules in the filament core.

Journal Article↗
PubMed1992

Brightness matching and flicker photometric data obtained over the full mesopic range.

Three normal observers made visual matches from 0.03 to 100 td on a 10 degree central field at 445, 560 and 630 nm, using two different methods: heterochromatic flicker photometry and direct comparison brightness matching. In a relative sensitivity vs illuminance plot, the brightness matches underwent smooth changes, while the flicker curve exhibited a step-like transition around 1 td, between two separate branches. A reverse Purkinje shift was found on the high mesopic branch at 630 nm, possibly due to cone-cone interactions, and on the low mesopic branch at 445 nm, with questionable origin. At 630 nm and 0.03 td, both methods yielded matches that were not truly scotopic but might not have addressed the same mechanisms.

Adult↗
PubMed1986

[Study of spatial function using the contrast sensitivity function. Cases of presbyopic subjects fitted with progressive glasses].

The spatial properties of the global visual system were measured on the basis of the contrast sensitivity function, in three presbyopic observers. Shape alterations of the contrast sensitivity curves were found depending on the experimental conditions: foveal vision, in far, intermediary and near vision, along central, 13 degrees nasal and 13 degrees temporal meridians (according to three parallels and three meridians), peripheral vision, in far and near vision, at 13 degrees and 26 degrees retinal eccentricities using the central or nasal part of the lens. The central meridian was found to be the most efficient part of the progressive lenses. These results strengthen the observations reported by ophthalmologists and progressive lens wearers.

Accommodation, Ocular↗