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F Guillemot

Publications and source records attributed to F Guillemot.

At least 91 records · Page 5Linked to original sources
PubMed1992

Retinal fate and ganglion cell differentiation are potentiated by acidic FGF in an in vitro assay of early retinal development.

One of the earliest events in vertebrate eye development is the establishment of the pigmented epithelium and neural retina. These fundamentally different tissues derive from the invaginated optic vesicle, or optic cup. Even after achieving a fairly advanced state of differentiation, the pigmented epithelium exhibits the same potential as the optic cup in that it can "transdifferentiate" into neural retina. C. M. Park and M. J. Hollenberg (Dev. Biol. 134, 201-205, 1989) discovered that administration of basic fibroblast growth factor, coupled with retinal removal, could trigger this transformation in vivo. We have developed a quantitative in vitro assay to study the role(s) of the fibroblast growth factor (FGF) family in this phenomenon and more generally in early retinal development. We found that several aspects of the process, including inhibition of pigmented epithelium differentiation, proliferation, and conversion to a retinal fate, were not strictly correlated. Both acidic and basic FGFs were found to potentiate all aspects of the process, with acidic FGF being 4 to 20 times more potent than basic FGF for inhibition of pigmentation and induction of retinal antigens. Depending upon its concentration, acidic FGF induced from 40% to 80% of the cells in the explants to produce antigens normally expressed by retinal ganglion cells, the first cell type to be generated in retinal development. Expression of such a ganglion cell marker could be directly stimulated in non-dividing cells as well as in dividing cells, indicating that conversion from the pigmented epithelial to retinal fate did not require cell division. These data suggest that acidic FGF, or a related molecule, may function in establishment of retinal fate from the optic cup. This effect may be directly or indirectly mediated by induction of retinal ganglion cell fate among multipotent progenitor cells.

Animals↗
PubMed1991

Treatment of diversion colitis by short-chain fatty acids. Prospective and double-blind study.

Diminished production of short-chain fatty acids (SCFA) by altered flora has been suggested in the pathogenesis of diversion colitis (DC). We evaluated prospectively the effectiveness of SCFA irrigation in 13 patients with excluded colon (eight males, five females; mean age, 48 years). The causes of diversion were inflammatory bowel disease (n = 4), colonic cancer (n = 2), sigmoid diverticulitis with perforation (n = 3), ischiorectal abscess (n = 2), and miscellaneous (n = 2). Patients were given, twice a day for 14 days in a double-blind manner, a 60-ml enema containing either SCFA (acetate: 60 mmol/liter; propionate: 30 mmol/liter; and N-butyrate: 40 mmol/liter) (Group 1; n = 7) or isotonic NaCl (Group 2; n = 6). Endoscopy with biopsies was performed before starting the trial (D1) and 14 days later (D14). On D1 all patients had endoscopic and histologic findings suggestive of DC. No endoscopic or histologic changes were observed on D14 in either group. We conclude that endoscopic and histologic lesions of DC were not improved by SCFA irrigation during the 14 days.

Adult↗
PubMed1991

Functional assessment of coloanal anastomosis with reservoir and excision of the anal transition zone.

Conservation of the anal transition zone (ATZ) has been deemed necessary for continence after coloanal anastomosis (CAA) with reservoir. Therefore, we have studied functional and manometric results after CAA with reservoir and excision of the ATZ in 18 consecutive patients (mean age, 65.2 years; ten males and eight females), 17.4 months after closure of a temporary loop colostomy (Study 1). Twelve of the 18 initial patients were studied again 30.2 months after closure (Study 2). In Study 1, all patients underwent 1) a standardized interview, 2) a manometric study with measurement of anal pressure at rest (PR), voluntary contraction (VC), inhibitor anal reflex (IAR), conscious sensation (CS), and maximum tolerable volume (MTV), and 3) a liquid continence test (LCT) with measurement of colonic reservoir pressure during infusion. In Study 2, patients underwent all the same tests except the LCT. Results were compared with those of six controls (mean age, 65.8 years; two females and four males). In Study 1, 14/18 patients were continent; PR, VC, and CS did not differ among continent patients, incontinent patients, and controls. MTV was significantly lower in incontinent patients (mean +/- SD, 165 +/- 46.5 ml) than in continent patients and controls (mean +/- SD, 261 +/- 50.8 ml vs. 250.7 +/- 83 ml). IAR was not observed in continent or incontinent patients but was observed in controls. Contraction waves in the colonic reservoir during LCT were more frequent in incontinent patients (4/4) than in continent patients (4/14), and their amplitudes were higher (119 vs. 32 mm Hg). In Study 2, 12/12 patients were continent; PR and MTV remained unchanged except in the two initially incontinent patients, in whom MTV was increased. VC was slightly increased (94.7 vs. 116 mm Hg). IAR remained absent in all patients. We conclude that 1) excision of the ATZ did not increase the risk of incontinence, and 2) poor functional results were mainly due to small MTV and contraction waves in the colonic reservoir.

Aged↗
PubMed1991

Could recurrent cholangitis after Roux-en-Y hepaticojejunostomy be explained by motor intestinal anomalies? A manometric study.

The aim of this study was to describe the motor patterns found in two patients with recurrent cholangitis episodes after Roux-en-Y hepaticojejunostomy. In one patient, cholangitis was due to a stenosis of the anastomosis between the limb and the left intrahepatic bile duct, while motility of the limb, duodenum, and distal jejunum was normal. In the second patient, no anatomical explanation was found for cholangitis attacks. However, although the duodenal motor activity was normal, the motility of the limb and of the jejunum below the jejunojejunal anastomosis was grossly abnormal: permanent minute rhythm, phase IIIs absent or rare and slowly propagated, all motor abnormalities that could promote bacterial overgrowth in the limb. This stresses the interest in performing motor studies of the Roux-limb when cholangitis remains unexplained after Roux-en-Y hepaticojejunostomy.

Anastomosis, Roux-en-Y↗
PubMed1989

The major histocompatibility complex in the chicken.

The chicken B complex is the first non-mammalian MHC characterized at the molecular level. It differs from the human HLA and murine H-2 complexes in the small size of the class I (B-F) and class II (B-L) genes and their close proximity. This proximity accounts for the absence of recombination between B-F and B-L genes and leaves no space for class III genes. Moreover the B-F and B-L genes are tightly linked to unrelated genes absent from mammalian MHCs, such as the polymorphic B-G genes and a member of the G protein beta subunit family. This linkage could form the basis for resistance to viral-induced tumors associated with some B complex haplotypes.

Animals↗
PubMed1989

Physical linkage of a guanine nucleotide-binding protein-related gene to the chicken major histocompatibility complex.

Several genes were found closely associated with major histocompatibility class I and class II beta-chain genes in chicken genomic DNA clusters by hybridizing tissue-specific cDNA probes to cosmid clones. A cDNA probe for one of these genes, probe C12.3 isolated from a chicken liver cDNA library, was used to clone the homologous sequence H12.3 from a human B-lymphoblastoid cell line cDNA library. C12.3 and H12.3 encode exactly the same 317-residue-long protein. The sequence of 12.3 shows significant homology with the two known guanine nucleotide-binding protein beta subunits (GP beta 1 and GP beta 2) and other proteins that all share the same segmented structure with seven internal homologous repeats about 45 residues in length. Unlike the chicken gene, the human H12.3 gene and its mouse counterpart are not located on the same chromosome as the major histocompatibility complex. A possible involvement of the C12.3 gene product in major histocompatibility complex-linked control of lymphocyte proliferation in chickens is discussed.

Amino Acid Sequence↗
PubMed1989

Jejunal motility during cyclic total parenteral nutrition in patients with Crohn's disease.

Our aim was to study the jejunal motility (a) in seven patients receiving longterm (median: 24 days) cyclic total parenteral nutrition (CTPN) for an acute exacerbation of Crohn's disease involving the ileum and/or the colon without any sign of occlusion and (b) in six healthy volunteers undergoing the same parenteral nutrition for one day after an overnight fast. Continuous recordings, lasting 20 hours, were carried out in patients after correction of their nutritional status and significant improvement of the Crohn's disease activity index. In five of the seven patients, we recorded seven to 14 phase III episodes (PIII) (median: 10), both more frequent and slower during the nocturnal part of the recording time as compared with diurnal. Seven to 18 PIIIs (median: 12) were found in controls. The overall duration of the motor activity was not different between these five patients and controls. In the remaining two patients, no PIII episode was recorded and 79% and 57% respectively of the whole recording time consisted of irregular motor activity. Our work therefore, shows that: (a) PIIIs remain and have a circadian variation in their periodicity and propagation velocity, in most of our patients undergoing longterm CTPN (b) CTPN does not determine a longer duration of motor rest of the small bowel in patients than in controls submitted for a short period of time to the same parenteral intake.

Adult↗
PubMed1989

Impaired bacterial flora in human excluded colon.

We compared the rectal microflora of 16 patients with surgically excluded colorectum with 16 healthy controls. The cause of diversion was inflammatory bowel disease (n = 10), colon cancer (n = 3), miscellaneous (n = 3). Six patients had a diversion colitis. In the excluded colorectum, the total bacterial count was only slightly lower than controls but the variety of the flora was significantly reduced. This reduction was confined to strict anaerobes, mainly the genus Eubacterium and Bifidobacterium. Among aerobes, enterobacteria were more often isolated than in controls. This altered microflora of excluded colorectum could be involved in the mucosal damage observed in some cases.

Adult↗
PubMed1989

[Iron chelation in children].

Iron-chelating treatment is indicated in all children on prolonged transfusion therapy (i.e., chiefly patients with thalassemia and Blackfan-Diamond anemia). The purpose of iron-chelating treatment is to prevent the development of manifestations of iron overload including cardiac hemosiderosis and insulin-dependent diabetes mellitus (which are two potentially fatal complications), hepatic cirrhosis, hypoparathyroidism, hypothyroidism, and delayed puberty. Deferoxamine is the only effective iron-chelating agent and should be given in a daily dose of 40 mg/kg at initiation of the transfusion program. Administration is by subcutaneous infusions from 8 to 10 hours per day. The goal of iron-chelating treatment is to maintain serum ferritin levels between 500 and 1,000 ng/ml. This long-term treatment is a significant burden for patients and it can be hoped that non-toxic iron-chelating agents, active by mouth, will become available.

Adolescent↗
PubMed1989

[Functional and motor study of retrosternal esophageal plasties].

The stomach may be used for esophageal reconstruction after resection of esophageal cancers. The aim of this study was to assess the motility of retrosternal esophagoplasty (RO) following the Akiyama procedure in 6 men (mean age: 56.7 years), at least two months after surgery by means of two techniques: a) manometry of the transplant with a multilumen perfused catheter in 50 and 40 cm from the incisor teeth including spontaneous (5 min) and poststimulation recordings, b) an isotopic method for assessing the gastric emptying of a meal labelled with 111In for the liquid phase and with 99mTc for the solid phase, compared to 12 volunteers as controls. Baseline pressure was 11.2 +/- 2.4 H2O cm without spontaneous activity. After dry and wet deglutition (5 ml of water), 6 patients showed synchronous rise in pressure, having mean amplitude of 12.7 +/- 2.3 cm H2O and lasting 4.3 +/- 1.2 s. Liquids T1/2 was 16.2 +/- 7.8 min in controls (p less than 0.01) and solids T1/2 was 17.7 +/- 6.4 min vs 61.7 +/- 16.5 min (p less than 0.001). The lack of propagated activity associated with rapid emptying of the meal through the plasty with no discrimination between solids and liquids suggests that RO does not participate actively in digestion.

Deglutition↗