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Biomedical subjects

G Paris

Publications and source records attributed to G Paris.

12 recordsLinked to original sources
PubMed2001

Sildenafil increases ocular perfusion.

PURPOSE: Our goal was to determine whether visual system responses to sildenafil accompany shifts in ocular perfusion. The human choroid, which supports the metabolic function of the outer retina, is an erectile tissue, analogous in many respects to the corpus cavenosum. METHODS: Right eyes of 12 normal adults were evaluated before and 2 h after 50 mg oral dose of sildenafil. Pulsatile ocular blood flow (POBF), intraocular pressure (IOP), Heidelberg retinal flowmetry (HRT), 4.26 cpd, 7.5 Hz temporally-modulated contrast sensitivity (CS), full-threshold C-20 frequency doubling technology (FDT) perimetry, and blood pressure (BP) were measured. RESULTS: POBF (+29.4%; p > 0.016) and CS (+33.6%; p > 0.014%) increased within 110 (+/-7.7) minutes after sildenafil administration. No subject demonstrated decreases in either variable. HRF flow values increase among 7 of the 9 eyes producing stable scans (+8.2%; p > 0.1). FDT values did not change significantly, nor did systemic pulse amplitude or mean IOP. CONCLUSIONS: Since IOP and systemic pulse amplitude both remained stable after sildenafil administration, while POBF values increased to a level nearly one third greater than baseline. It appears sildenafil can induce intrinsic change in the choroidal vasculature, with an apparently positive impact on pericentral contrast sensitivity. This effect may be of clinical utility.

Administration, Oral↗
PubMed2001

Probing molecular function of trypanosomal sialidases: single point mutations can change substrate specificity and increase hydrolytic activity.

Sialidases are present on the surface of several trypanosomatid protozoan parasites. They are highly specific for sialic acid linked in alpha-(2,3) to a terminal beta-galactose and include the strictly hydrolytic enzymes and trans-sialidases (sialyl-transferases). Based on the structural comparison of the sialidase from Trypanosoma rangeli and the trans-sialidase from T. cruzi (the agent of Chagas' disease in humans), we have explored the role of specific amino acid residues sought to be important for substrate specificity. The substitution of a conserved tryptophanyl residue in the two enzymes, Trp312/313-Ala, changed substrate specificity, rendering the point mutants capable to hydrolyze both alpha-(2,3)- and alpha-(2,6)-linked sialoconjugates. The same mutation abolished sialyl-transferase activity, indicating that transfer (but not hydrolysis) requires a precise orientation of the bound substrate. The exchange substitution of another residue that modulates oligosaccharide binding, Gln284-Pro, was found to significantly increase the hydrolytic activity of sialidase, and residue Tyr119 was confirmed to be part of a second binding site for the acceptor substrate in trans-sialidase. Together with the structural information, these results provide a consistent framework to account for the unique enzymatic properties of trypanosome trans-sialidases.

Amino Acid Substitution↗
PubMed1994

Randomised comparison of amoxycillin and erythromycin in treatment of genital chlamydial infection in pregnancy.

Erythromycin, the standard treatment for chlamydial infection in pregnant women, commonly causes side-effects, which limits its efficacy. In a randomised, double-blind study, we compared amoxycillin with erythromycin in this setting. 210 pregnant women with Chlamydia trachomatis infection were randomly assigned 7 days' treatment with amoxycillin (500 mg three times daily) or erythromycin (500 mg four times daily). Control cultures were obtained 21 days after treatment, during late pregnancy, and from the infant within a week of birth. Treatment was judged a failure if any post-treatment culture was positive or if the patient had to stop therapy because of severe side-effects. 11 women (5.2%) were lost to follow-up. 1 (of 100) amoxycillin-treated women had to stop treatment because of severe side-effects compared with 12 (of 99) erythromycin-treated women (p = 0.002). 1 woman in the amoxycillin group had a positive culture at the third-trimester examination. No positive post-treatment culture was found in the erythromycin group. Severe gastrointestinal side-effects were more common in women who received erythromycin (31 vs 6%, p < 0.001). The overall failure rate was therefore 2% in the amoxycillin group and 12% in the erythromycin group (p = 0.005). These results suggest that amoxycillin is an acceptable alternative to erythromycin for C trachomatis infection in pregnant women.

Adult↗
PubMed1989

[The mother and infant with Steinert's myotonic dystrophy].

Pregnancy and delivery present a number of risks for the mother suffering from myotonic dystrophy, and for her infant. Most of the time, she does not even know that she is affected by the disease and a carrier of the gene. We review the complications of pregnancy and delivery in myotonic patients, and propose a simple management with specific items for each gestational period. The child of a dystrophic mother has a 50% risk of inheriting the abnormal gene. He may also exhibit a developmental and malformation syndrome called "congenital myotonic dystrophy". From the beginning, he may show respiratory distress, thereafter inability to swallow and severely hypotonia. Later, he may demonstrate mental retardation. Some of the most obvious signs found in neonates in our practice are illustrated. We also add a few tests to the list of those already recommended for these children.

Female↗
PubMed1980

Use of dextran gradient for the study of the development of mitochondria and glyoxysomes during the germination of pine seeds.

An isotonic gradient of dextran-sucrose was used for the separation of glyoxysomes and mitochondria. By this method, these organelles were easily separated from pine seeds on the first day of germination, with densities of 1.110 and 1.175 g/ml for mitochondria and glyoxysomes, respectively. Nevertheless, these sedimented closely at a density of 1.075 g/ml when coming from 30-day stratified seeds; and both organelles highly increased their densities as germination proceeded. A mild treatment of the organelles from 30 days stratified seeds with SDS modified their sedimentation pattern, being similar after this treatment to that of the particles from the seeds on the first day of germination.

Cell Separation↗