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Biomedical subjects

L Gauthier

Publications and source records attributed to L Gauthier.

At least 73 records · Page 4Linked to original sources
PubMed1989

Evaluation of the clastogenicity of water treated with sodium hypochlorite or monochloramine using a micronucleus test in newt larvae (Pleurodeles waltl).

We have previously described a micronucleus test using erythrocytes from larvae of the urodele amphibian Pleurodeles waltl (pleurodele). The test is based on a comparison of the levels of micronucleated erythrocytes in blood smears from larvae reared in water containing a clastogen, with the levels from larvae reared in purified water. We have employed this test to evaluate mutagenic activity of chlorinated or monochloraminated water devoid of all organic matter. (i) The level of micronuclei in erythrocytes was compared between a group of larvae reared for 12 days in chlorinated reconstituted ultrapure water treated with sodium hypochlorite, and a control group reared in just the reconstituted water. Sodium hypochlorite was added when both the food and medium were changed each day. Chlorine levels of 0.125 and 0.25 p.p.m. led to significant elevations of micronuclei. (ii) The possibility of indirect effects of chlorine through chemical interactions with the food were also investigated, using the following scheme: larvae were left for 3 h in chlorinated reconstituted ultrapure water and then placed in non-chlorinated water. Food was only introduced when they were transferred to the non-chlorinated water. This procedure was repeated for 12 consecutive days. Control larvae were reared in non-chlorinated water throughout this period. In this case results were also positive when the larvae were exposed for only 3 h to the chlorine (0.2 p.p.m. for 12 days) in the absence of food. (iii) This was the same as experiment 1 except that the water was chlorinated with monochloramine instead of sodium hypochlorite.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Concentration-dependent repression of the soluble and membrane components of the Streptococcus mutans phosphoenolpyruvate: sugar phosphotransferase system by glucose.

Growth of Streptococcus mutans Ingbritt in continuous culture (pH 7.0, dilution rate of 0.1 h-1) at medium glucose concentrations above 2.6 mM resulted in repression of the sugar-specific membrane components, enzyme IIGlc (EIIGlc) and EIIMan, of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). In one experiment, significant repression (27-fold) was observed with 73 mM glucose when the glycolytic capacity of the cells was reduced by only 2-fold and when the culture was still glucose limited. In a more comprehensive experiment in which cells were grown in continuous culture at eight glucose concentrations from 2.6 to 304 mM, in addition to repression of specific EII activities for glucose, mannose, 2-deoxyglucose, and fructose, synthesis of the general protein, EI, was repressed at all glucose levels above 2.6 mM to a maximum of 4-fold at 304 mM glucose when the culture was growing with excess glucose (i.e., nitrogen limited). The other PTS general protein, HPr, was less sensitive to the exogenous glucose level but was nevertheless repressed fourfold under glucose-excess conditions. The Km for glucose for EIIGlc increased from 0.22 mM during growth at 3.6 mM glucose (glucose limited) to 0.48 mM at 271 mM glucose (glucose excess). The shift from heterofermentation to homofermentation during growth with increasing glucose levels suggests the involvement of glycolytic intermediates, ATP, or another high-energy phosphate metabolite in regulation of the synthesis of the PTS components in S. mutans.

Bacterial Proteins↗
PubMed1989

A fibrin sealant for perforated and preperforated corneal ulcers.

Fibrin sealant is used to close perforated or preperforated corneal ulcers. In addition to the usual advantages of cyanoacrylates it is degraded physiologically and provides a good support for corneal healing. Corneal grafting can be avoided when contraindicated or postponed when conditions allow. This technique has been successful in nine eyes of eight patients.

Adolescent↗
PubMed1989

Canadian collaborative study of tetrahydroaminoacridine (THA) and lecithin treatment of Alzheimer's disease: effect on mood.

Several lines of evidence have implicated acetylcholine (ACh) as one of the neurotransmitters found to be decreased in Alzheimer's disease (AD). Various methods of cholinergic augmentation have been attempted, with mixed results. Tetrahydroaminoacridine (THA), an acetylcholinesterase inhibitor, is currently being investigated at the McGill Centre for Studies in Aging. Preliminary uncontrolled data from a 10-week clinical trial of THA and lecithin, reported elsewhere, suggest a clinically modest but statistically significant beneficial effect on cognition, although problems exist with side effects, particularly gastrointestinal. Since the suggestion by Janowsky in 1972 that cholinergic neurotransmission may exert an inhibitory or depressant effect on mood, the evidence accumulated in the literature has been inconclusive. We undertook to assess several potential pretreatment correlates of depressive symptoms in AD and to monitor the course of these symptoms during the 10 week treatment period, using the Geriatric Depression Scale (GDS) of Brink and Yesavage. Pretreatment GDS scores were found to correlate with degree of overall disability and dementia as measured by the Rapid Disability Rating Scale (RDRS) and the Mini Mental State Examination (MMS), respectively. GDS scores over the treatment period did not change to a statistically significant degree. The meaning of these results is discussed, particularly with reference to the difficulty of diagnosis and measurement of depression in the setting of dementia.

Aged↗
PubMed1989

Frequency of chlamydia in patients with vernal keratoconjunctivitis.

Ten years ago, we surmised that VKC could be provoked by chlamydia. 34 patients without any contamination of trachomatous origin were recently studied. We performed examinations of biopsies (histology and ultrastructure), serology, tissue group and specific allergen skin tests. Our findings indicate that Chlamydia could be an allergen provoking VKC in atopic patients.

Adolescent↗
PubMed1989

[Use of a fibrin glue (Tissucol) for treating perforated or pre-perforated corneal ulcer].

Treatment of perforated and preperforated corneal ulcers is a difficult task. As emergency penetrating keratoplasty results in poor visual outcome, surgical glue has been suggested as an alternative solution, but poor corneal tolerance for cyanoacrylate made this treatment non satisfactory. We treated 15 corneal ulcers (11 perforations, 2 descemetoceles and 2 deep ulcers) with a fibrin glue. Cicatrisation was obtained in 14 cases by this technic. In one case, cicatrisation was not satisfactory and penetrating keratoplasty was performed 3 days later. This method permits healing of the corneal perforation without the necessity of performing penetrating keratoplasty either if the perforation is distant from the visual axis or if penetrating keratoplasty is contraindicated. In other cases it permits a later penetrating keratoplasty to be performed an a quiet eye. We think this technic can be useful in corneal perforations less than 2 mm in diameter and in chronic deep ulcers difficult to heal.

Corneal Ulcer↗
PubMed1989

[Etiology of childhood visual impairment in 1989].

We studied the etiologies of visual impairment in the 171 children managed at the Alfred Peyrelongue Center, Ambarès France. This center is open to visually impaired children aged 3 to 20 years and free of significant motor or cognitive handicaps. Etiologies of visual impairment in the decreasing order of frequency were as follows: cataract (31 cases), tapetoretinal degeneration (28 cases), optic nerve lesion (22 cases), retinopathy of prematurity (13 cases), coloboma malformations (13 cases), severe congenital myopia (12 cases), congenital glaucoma (10 cases), congenital nystagmus (8 cases), congenital achromatopsia (6 cases), retinal abnormalities, and ocular injuries. We discuss these results, compare them with those of a similar study carried out in the same center in 1978, and briefly review the literature.

Adolescent↗