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Biomedical subjects

M Villain

Publications and source records attributed to M Villain.

44 records · Page 3Linked to original sources
PubMed1996

An expression system for the single-step production of recombinant human amidated calcitonin.

Amidating mouse pituitary cells (AtT-20) have been engineered to secrete human calcitonin (hCT) in the fully active amidated form, without the need of additional enzymatic or chemical modifications. The 141-residue human calcitonin precursor has first been cloned in the eucaryotic expression vector pRc/RSV, and the resulting plasmid pRc/RSV/hCT introduced in AtT-20 cells. After transfection, 122 independent clones resistant to G-418 were selected and screened for calcitonin production using a competitive ELISA specifically designed to detect the amidated form of calcitonin. One of these clones was amplified and showed expression of 17 ng/ml of hCT, with a 70% increase in productivity after cAMP treatment. Calcitonin was partially purified from culture medium by two sequential steps of reverse-phase chromatography and characterized in terms of immunoreactivity and molecular weight by TOF-MALDI mass spectroscopy, which confirmed the intended chemical nature and the presence of the C-terminal amidated residue.

Amino Acid Sequence↗
PubMed1996

Differential effect of ischemia/reperfusion on pigmented and albino rabbit retina.

The purpose of the study was to compare the retinal sensitivity of pigmented and albino rabbits to ischemia/reperfusion-induced electroretinogram (ERG) alterations and optic nerve morphological changes. High intraocular pressure (HIOP) was induced by applying a suction-cup on the eye and a depression with an ophthalmodynamometer. HIOP was maintained for lengths of time (30-75 min). Flash ERGs were recorded in dark-adapted animals for ischemia and 2 h reperfusion periods. Two weeks later, histological examination of the retinas and optic nerves was done. Albino rabbits submitted to 45 min HIOP failed to recover b-wave ERG amplitude after 2 h reperfusion, whereas pigmented animals presented a total ERG recovery even if ischemia was maintained as long as 75 min. Intravenous treatment of albino animals with Lazaroid U74389G led to significant ERG recovery at reperfusion. Histological studies show that pigmented rabbit optic nerves suffered less damage than the albino ones. These results emphasize the role of the pigmentary status of the animals in the retinal sensitivity to ischemia. Neuroprotection afforded by the antioxidant U74389G suggests that ocular pigments could also protect the retinal functional integrity through a free radical scavenging activity.

Albinism, Ocular↗
PubMed1996

[Bilateral ocular blast injury after refractive surgery by 2 current techniques. Comparative anatomo-clinical analysis of a case].

Radial keratotomy reduces the strength of the cornea front of a trauma by blast. The authors present and analyze the case of a 25-year-old patient having been submitted to an ocular bilateral trauma by explosion. Twenty-two months earlier he had undergone radial keratotomy (RK) in the left eye followed 8 days later by photorefractive keratectomy (PKR) in the right eye for a -6,00 d. myopia RLE. Though the trauma by blast essentially reached the right eye, the corneal anatomical damages were more important in the left eye. This is according to us the first case report of trauma on eye subjected to PRK. We appreciate the clinical differences presented by each eye.

Adult↗
PubMed1996

[Sub-temporal supra-petrous approach to the horizontal portion of the sub-petrous internal carotid artery. Technique, indications, incidents and accidents].

Cavernous sinus exploration, anterior middle fossa transpetrous approach, and saphenous vein graft bypass require proximal control of the horizontal segment of the petrous internal carotid artery. Exposing the petrous portion of the internal carotid artery is not without the potential for serious complications (cochlea, facial nerve, auditory tube, musculus tensor tympani). With guidance from the classicaly landmarks within Glasscock's triangle, the bony petrous carotid canal can be unroofed. The authors describe an alternative method for obtaining direct vascular control under the trigeminal ganglion, safety unroofing of the carotid canal and control of the posterior face of the carotid bend. The indications, advantages, and disadvantages of this approach are described in details, along with its use in seven patients.

Carotid Artery, Internal↗
PubMed1995

Antigenicity of topochemically related peptides.

Antibodies raised in rabbits against multimeric all-L peptides (MAP's) were first made monospecific by affinity chromatography on immobilized antigen columns and then tested for their ability to cross-react with topologically related variants of the parent antigen, where the chirality of each amino-acid residue (inverso derivatives), or the peptide sequence orientation (retro derivatives), was inverted, or where both modifications were simultaneously introduced (retro-inverso derivatives). Retro, inverso, and retro-inverso forms of the parent peptide were prepared, both in the linear as well as in the BSA-conjugated form, and found to cross-react to a significant extent with affinity purified polyclonal antibodies raised against the parent peptide. Peptide variants displayed similar dose-dependent inhibitory effects on the interaction between immobilized parent antigen and affinity purified antibodies. Analysis of molecular models of the peptide variants in the trans-configuration suggested that the topological equivalence of alternating side chains in the series of related peptides may be responsible for the observed cross-recognition, leading to the formation of similar recognition surfaces which could mimic the parent peptide antigenic structure.

Amino Acid Sequence↗
PubMed1993

The trochlear nerve: anatomy by microdissection.

This work is based on the microscopic study of 30 trochlear nerve trunks (15 heads). In 17 cases, the trunk arose from two nerve bundles, in 8 cases from one bundle, and for the other 5 nerves, three or four bundles. The mean total length of the trochlear nerve was 86 mm. The nerve may be separated into the 3 following parts: infratentorial, intracavernous, intraorbital. In all 30 cases studied, the first part of the nerve was infratentorial, thus leading us to suggest the term "infratentorial part" for this segment of the nerve. In 27 cases, contact was found with the superior cerebellar artery, in the infratentorial part. In the intracavernous part of ten nerves we found two rami tentorii and in eight cases fibers were exchanged with the ophthalmic nerve. In the orbit, 18 trochlear nerves crossed the posterior ethmoidal artery. 23 trochlear nerves ended on the medial face of the superior oblique muscle. The remaining 7 ended at the superior border of the muscle.

Adult↗
PubMed1992

Cytotoxicity evaluation of antiseptics and antibiotics on cultured human fibroblasts and keratinocytes.

Infection is the greatest problem in burn patients and topical antimicrobial agents must be chosen with great care, especially when cultured skin is grafted. We examined the cytotoxic effect of six antiseptics and six antibiotics commonly used on cultured human fibroblasts and keratinocytes. Cultured cells were exposed for 15 min to Hibitane (chlorhexidine), Biseptine (chlorhexidine+benzalkonium chloride+benzylic alcohol), Benzalkonium Chloride, Yellow Betadine (polyvidone-iodine+nonoxinol), Betadine Scrub (polyvidone-iodine+quaternary ammonium) and Green Betadine (polyvidone-iodine) and viability was determined using the MTT test. At therapeutic concentrations all the antiseptics are cytotoxic for fibroblasts and keratinocytes. Additionally the cells were exposed for 48 h to vancomycin, colistin, amikacin, imipeneme, pefloxaxin, piperacillin and cell viability was determined using the MTT test. The concentrations of antibiotics corresponding to the plasma peak obtained after therapeutic application were not cytotoxic to the tested cells. The CD50 was much higher than the MIC (from 125 to 875 times for keratinocytes and from 1400 to 5900 times for fibroblasts). These data suggest that commonly applied antiseptics must not be used before grafting cultured skin grafts. After grafting any infection can be controlled with topical applications of appropriate antibiotics.

Anti-Bacterial Agents↗