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Biomedical subjects

J Richard

Publications and source records attributed to J Richard.

At least 55 records · Page 3Linked to original sources
PubMed1996

A simple computer-assisted method to identify schistosome cercariae.

Several methods have been suggested to identify schistosome cercariae. In the present work, a new method is proposed, based on the analysis of the distribution of sensory endings (sensillae) on the body of the cercariae, revealed by an impregnation with silver nitrate. We determined the mutual distances between the sensillae and calculated the mean values, standard deviations, coefficients of asymmetry, and of kurtosis of the distribution of these mutual distances. Applied to two species, Schistosoma mansoni from Brazil and S. intercalatum from Cameroon, these mutual distances had the same mean value and the same standard deviation but quite different coefficients of symmetry (0.34 +/- 0.11 versus 0.73 +/- 0.08; P < 0.0001) and of kurtosis (-0.82 +/- 0.27 versus -0.58 +/- 0.31; P < 0.0001). The latter two indices were therefore very effective for discriminating the two species. The present method can be applied to other species and to hybrids in the field.

Animals↗
PubMed1995

Early marriage among rural and urban females of south India.

Data on 2972 marriages in rural areas and 1180 marriages in urban areas of North Arcot Ambedkar district of South India, during 1982-88, were analysed. The mean age at marriage of females was 18.6 in the rural and 19.6 in the urban area. The proportion of females married before attaining the legal age of 18 years was higher among the rural community (36.8%) than in the urban community (28.9%). Univariate analysis revealed an association between early age at marriage and the socioeconomic variables religion, caste, consanguinity, marital distance, spousal age difference, education and occupation of both bride and bridegroom, and socioeconomic status of the family. Multivariate analysis showed an independent relationship of marital distance and bridegroom's occupation with early age at marriage of females in the rural area alone and the bridegroom's education in the urban area alone. Consanguinity, spousal age difference and bride's education were found to be independently related with early age at marriage of females in both rural and urban areas.

Adolescent↗
PubMed1995

SR 33589, a new amiodarone-like antiarrhythmic agent: electrophysiological effects in anesthetized dogs.

We compared the electrophysiological effects of a new amiodarone-like agent, SR 33589, with those of amiodarone. Mongrel dogs were anesthetized with chloralose, and electrodes were implanted in right atrium and ventricle for electrical stimulation and regional ECG measurement. Sinus cycle length (CL), AH interval, Wenckebach CL (WCL), atrial, atrioventricular node, and ventricular effective refractory periods (AERP, AVNERP, VERP), and parameters calculated from surface ECG were measured. SR 33589 was administered intravenously (i.v.) at 1, 2.5, or 5 mg/kg followed 60 min later by a second similar dose. The same protocol was followed with amiodarone 5 mg/kg, which reduced heart rate (HR) by 19% (p < 0.05), increased WCL by 31% (p < 0.01), AH interval by 14% (p < 0.05) and AERP, AVNERP, and VERP by 13% (p < 0.05), 19% (p < 0.05), and 11% (p < 0.01) respectively. No effect was observed on HV or PQ intervals. A second administration of 5 mg/kg changed these indexes further. SR 33589 (2.5 mg/kg) reduced HR by 21% (p < 0.001), increased WCL by 44% (p < 0.001), AH interval by 24% (p < 0.01), and AERP, AVNERP, and VERP by 17% (p < 0.001), 63% (p < 0.01), and 15% (p < 0.01) respectively, with an 18% increase in PQ interval (p < 0.05) but no significant effect on HV interval. Higher doses (5 mg/kg) and/or administration of a second dose both resulted in greater changes. Both amiodarone and SR 33589 prolonged VERP more at longer CL than at shorter CL, but the degree of reduction at shorter CL was less with SR 33589 than with amiodarone. Results suggest that acute administration of SR 33589 results in electrophysiological actions similar to those produced by amiodarone.

Amiodarone↗
PubMed1995

Activity and purification of linenscin OC2, an antibacterial substance produced by Brevibacterium linens OC2, an orange cheese coryneform bacterium.

An orange cheese coryneform bacterium isolated from the surface of Gruyère of Comté and identified as Brevibacterium linens produces an antimicrobial substance designated linenscin OC2. This compound inhibits gram-positive food-borne pathogens including Staphylococcus aureus and Listeria monocytogenes but is not active against gram-negative bacteria. Linenscin OC2 caused viability loss and lysis of the test organism, Listeria innocua. Electron microscopy showed that linenscin OC2 induces protoplast formation and cell lysis. The native substance is resistant to proteolytic enzymes, heat, and organic solvents and stable over a wide range of pH. The molecular weight of the native linenscin OC2 was estimated by gel chromatography to be over 285,000. Linenscin OC2 was purified by ammonium sulfate precipitation, 2-propanol extraction, and reverse-phase chromatography. Direct detection of antimicrobial activity on a sodium dodecyl sulfate-polyacrylamide gel suggested an apparent molecular mass under 2,412 Da. Molecular mass was determined to be 1,196.7 Da by mass spectrometry. Amino acid composition analysis indicated that linenscin OC2 may contain 12 residues.

Amino Acids↗
PubMed1995

Oligopeptides are the main source of nitrogen for Lactococcus lactis during growth in milk.

The consumption of amino acids and peptides was monitored during growth in milk of proteinase-positive (Prt+) and -negative (Prt-) strains of Lactococcus lactis. The Prt- strains showed monophasic exponential growth, while the Prt+ strains grew in two phases. The first growth phases of the Prt+ and Prt- strains were in same, and no hydrolysis of casein was observed. Also, the levels of consumption of amino acids and peptides in the Prt+ and Prt- strains were similar. At the end of this growth phase, not all free amino acids and peptides were used, indicating that the remaining free amino acids and peptides were unable to sustain growth. The consumption of free amino acids was very low (about 5 mg/liter), suggesting that these nitrogen sources play only a minor role in growth. Oligopeptide transport-deficient strains (Opp-) of L. lactis were unable to utilize oligopeptides and grew poorly in milk. However, a di- and tripeptide transport-deficient strain (DtpT-) grew exactly like the wild type (Opp+ Dtpt+) did. These observations indicate that oligopeptides represent the main nitrogen source for growth in milk during the first growth phase. In the second phase of growth of Prt+ strains, milk proteins are hydrolyzed to peptides by the proteinase. Several of the oligopeptides formed are taken up and hydrolyzed internally by peptidases to amino acids, several of which are subsequently released into the medium (see also E.R.S. Kunji, A. Hagting, C.J. De Vries, V. Juillard, A.J. Haandrikman, B. Poolman, and W.N. Konings, J. Biol. Chem. 270:1569-1574, 1995).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1995

Specificity of peptide transport systems in Lactococcus lactis: evidence for a third system which transports hydrophobic di- and tripeptides.

A proton motive force-driven di-tripeptide carrier protein (DtpT) and an ATP-dependent oligopeptide transport system (Opp) have been described for Lactococcus lactis MG1363. Using genetically well-defined mutants in which dtpT and/or opp were inactivated, we have now established the presence of a third peptide transport system (DtpP) in L. lactis. The specificity of DtpP partially overlaps that of DtpT. DtpP transports preferentially di- and tripeptides that are composed of hydrophobic (branched-chain amino acid) residues, whereas DtpT has a higher specificity for more-hydrophilic and charged peptides. The toxic dipeptide L-phenylalanyl-beta-chloro-L-alanine has been used to select for a di-tripeptide transport-negative mutant with the delta dtpT strain as a genetic background. This mutant is unable to transport di- and tripeptides but still shows uptake of amino acids and oligopeptides. The DtpP system is induced in the presence of di- and tripeptides containing branched-chain amino acids. The use of ionophores and metabolic inhibitors suggests that, similar to Opp, DtpP-mediated peptide transport is driven by ATP or a related energy-rich phosphorylated intermediate.

Amino Acid Sequence↗
PubMed1995

Facilitation of acetylcholine release and cognitive performance by an M(2)-muscarinic receptor antagonist in aged memory-impaired.

Aged memory-impaired (AI) and unimpaired (AU) 24-25-month-old Long-Evans rats were used to investigate the integrity of various cholinergic markers during normal aging and to establish if alterations can possibly relate to cognitive disabilities. AI and AU rats were classified on the basis of their performance in the Morris swim maze task. Choline acetyltransferase activity (ChAT) was not differentially altered in various cortical and hippocampal areas between these two groups. Similarly, quantitative receptor autoradiography did not reveal significant differences in 3H-pirenzepine/muscarinic M1 and 3H-hemicholinium-3/high-affinity choline uptake binding sites in AI versus AU rats. In contrast, 3H-AF-DX 384/putative muscarinic M2 binding was significantly increased in certain cortical and hippocampal areas of the age-impaired animals. These increments were correlated with decreased in vivo acetylcholine (ACh) release capacity in the AI rats. Most interestingly, the muscarinic M2 antagonist BIBN-99 reversed, in a dose-dependent manner, the impaired ACh release as well as the cognitive deficits observed in the AI group. Similarly, BIBN-99 reversed scopolamine-induced amnesia in young animals. The efficacy of BIBN-99 likely relates to its antagonistic properties on negative muscarinic M2 autoreceptors that are apparently increased in the AI animals, leading to altered ACh release. Taken together, these findings strengthen the role of ACh in learning and memory and may have implications for the treatment of degenerative disorders associated with impaired cholinergic functions, such as Alzheimer's disease.

Acetylcholine↗
PubMed1995

[Extra-pulmonary tuberculosis in Antananarivo. Principal localizations and biological diagnosis].

We describe the state of extrapulmonary tuberculosis in the capital of Antananarivo, a city of high endemicity for tuberculosis but very low endemicity for HIV infection. The Laboratory of Mycobacteria in the Institut Pasteur of Madagascar had examined from August 94 to April 95, 543 pathological samples issued from 295 patients clinically suspected of extrapulmonary tuberculosis (64% male and 36% female). The diagnosis of tuberculosis was confirmed for 47.7% of the patients (141/295), using either the culture technique or the histopathological method: 93% of them had an unique localization whereas 7% had a double localization. The most frequent form encountered was the pleural localization (77.8%), followed by the lymphadenopathic form (8,4%) and the abdominal form (6.9%). The confirmation rate on biopsies was 67% by histopathological method compared to 55% by the culture. On the fluid samples, the confirmation rate was 20.9% using the culture. The agreement between histology and culture was 70.3%. Of the 138 strains identified, 135 were M. tuberculosis, 1 M. bovis and 2 environmental mycobacteria.

Adolescent↗
PubMed1995

[660 cases of histologic extra-pulmonary tuberculosis at the Pasteur Institute in Madagascar].

A 33 months retrospective study (from September 1992 to May 1995) of 8525 patients indicated that the incidence of histologic extrapulmonary tuberculosis (EPT) was 7,7%. The 8341 malagasy native patients presented an incidence of 7.8%. Male are more frequently infected than female. Most samples came from Antananarivo, with a prevalence reaching 12,5% while it was only 2,9% in the provinces. Most pathologic EPT were pleural tuberculosis (55,6%) and ganglial tuberculosis (34%). Peritoneal tuberculosis were much less frequent. According to literature data in Madagascar, the incidence of histologic EPT is obviously increasing.

Adolescent↗
PubMed1994

Colorado tick fever in a resident of New York City.

When a traveler returns from abroad with a febrile illness, clinicians appropriately concern themselves with a potentially vast array of diagnostic exotica. The patient we describe herein did not leave the United States but nevertheless posed the same clinical dilemma after returning home to New York City from the western United States. This case of Colorado tick fever, acquired on the Utah-Colorado border and first expressed in Manhattan, serves as a useful reminder of the importance of taking a careful travel history for national as well as international travelers.

Antibodies, Viral↗
PubMed1994

Muscarinic and nicotinic modulation of cortical acetylcholine release monitored by in vivo microdialysis in freely moving adult rats.

The aim of the present study was to investigate, using in vivo dialysis, the existence of muscarinic and nicotinic receptors controlling acetylcholine release in the cortex of freely behaving rats. Various muscarinic receptor antagonists, including the nonselective blocker atropine, and a variety of M2 drugs (AF-DX116, AF-DX384, AQ-RA 741) potently stimulated, in a concentration-dependent manner, the in vivo release of acetylcholine in the rat cortex. The effects of all these antagonists were long lasting. The nature of these putative muscarinic autoreceptors is likely of the pharmacologically defined M2 subtype on the basis of the high potency of the antagonists of the AF-DX series and the variability and shorter duration of action of the effects of the prototypic M1 blocker, pirenzepine. 4-DAMP, a purported M3 blocker, also potently stimulated in vivo cortical acetylcholine release, but this likely relates to its now established, rather limited selectivity for any given muscarinic receptor subtypes. Peripheral and central injections of nicotine also induced the in vivo release of acetylcholine in the rat cortex, albeit with a lower potency and shorter duration of action than muscarinic antagonists. Interestingly, the combination of a muscarinic antagonist, such as atropine, AF-DX 116, or AF-DX384, in the presence of nicotine, induced tremendous releases of cortical acetylcholine up to 8- to 10-fold over basal values. This is clearly more than a simply additive effect, and it reveals the great capacity of cortical cholinergic nerve terminals to synthesize and release acetylcholine. Optimal pharmacological manipulations of these putative muscarinic and nicotinic autoreceptors could thus be useful in disorders in which the activity of cholinergic inputs is decreased, such as in Alzheimer's disease.

Acetylcholine↗
PubMed1994

Isolation and identification of cheese-smear bacteria inhibitory to Listeria spp.

A newly developed hydrophobic grid membrane method was used to rapidly screen 105 traditional French cheeses for surface smear microorganisms inhibitory to Listeria monocytogenes strain V7. Approximately 125,000 colonies comprising a wide variety of bacteria were examined of which less than 0.1% produced visible zones of inhibition. Isolates possessing antilisterial activity consisted of various strains of Enterococcus faecalis, Staphylococcus xylosus, Staphylococcus warneri and coryneform bacteria, including one orange coryneform resembling Brevibacterium linens. All strains of E. faecalis and the orange coryneform that inhibited L. monocytogenes V7 exhibited strong inhibition against a panel of 21 Listeria strains comprised of L. monocytogenes (14 strains), L. innocua (two strains), L. ivanovii (two strains), L. seeligeri (two strains) and L. welshimeri (one strain). The remaining cheese isolates showed moderate to weak inhibition towards the same set of Listeria strains. Inhibitory substances produced by all strains except the orange coryneform were sensitive to one or more of five proteolytic enzymes tested and were therefore classified as bacteriocin-like inhibitory agents.

Actinomycetales↗
PubMed1994

[Palliative surgery of esophageal cancer in Djibouti: the value of colonic esophagoplasty].

Because of delayed diagnosis in Black Africa, esophageal cancer is often seen at an advanced stage when dysphagia is total and eating becomes impossible. At this stage, palliative surgery is the only alternative to enable the patient to eat. Over a 27 month period in Djibouti, palliative therapy for esophageal cancer was indicated in 49 patients and surgery was performed in 37 of these patients. Out of 26 patients to whom gastrostomy was proposed, there were 12 that refused and 14 who underwent the procedure with a mean survival of 40 days. Esophageal bypass was performed in 23 patients. In 22 of these patients, the procedure was colon interposition and in the remaining case a gastric tube was used. There was one postoperative death. Excluding 3 patients that suffered cervical fistulas and one patient who required redo to remove a textiloma, postoperative recovery was uneventful. Patients resumed eating and were able to return home less than one month after the procedure. This study demonstrates that colon interposition can be performed in Black Africa despite limited availability of preoperative and postoperative intensive care facilities. It is a useful alternative for the management of malignant and benign stenosis.

Adult↗