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Biomedical subjects

P Richard

Publications and source records attributed to P Richard.

At least 145 records · Page 8Linked to original sources
PubMed1995

Prevalence of L. loa and M. perstans filariasis in southern Cameroon.

The prevalence and microfilarial density of Loa loa and Mansonella perstans filariasis have been determined in three successive surveys in one village in the dense rainforest of Southern Cameroon. The prevalence of L. loa microfilaraemia was 30.9% with a geometric mean density of 81.4 microfilariae/30 microliter blood. There was no difference between men and women. The prevalence increased with age from 14.5% at 0-9 years to 52.9% at 40-49 years, whereafter it stablized. The microfilarial density increased until the age of 30-39 years. The highest densities have been found around noon, although the difference was not significant. The prevalence of M. perstans microfilaraemia was 26.6% with a median density of 2.0 microfilariae/30 microliter blood. Both prevalence and density were increasing with age and were higher for men than for women. The time of day that the blood sample was taken had no influence on the microfilarial density of M. perstans.

Adolescent↗
PubMed1995

[Hemi-arthroplasty of the shoulder: radiological, functional and dynamic studies].

From September 1973 to October 1992, forty-three shoulder arthroplasties were performed in forty-one patients with complicated fractures or degenerative disease. Radiological and functional assessment with a mean follow-up time of forty-five months permitted us to review twenty patients with fifteen Neer II prosthesis, three isoelastic prosthesis and two total shoulder replacements. Of these, eleven presented with traumatic injuries and four with degenerative disease. The mean age at operative time was 61 years. Radiological evaluation showed that all cases had a retroversion of about 30 degrees. Normal humeral length and lateral shifting were not achieved in most patients; in fact only one had a restored length and lateral shifting. The mean scapulothoracic range of motion was found to be half that of a normal gliding shoulder (angle 30 degrees instead of 60 degrees). The subacromial space was diminished by one third in all cases. Relief of shoulder pain was the most significant finding. Mobility was restored to a level of about 75% of normal according to Constant's Scale. Dynamometric measures showed an important loss of force (47% of normal) despite a normal external rotation force. Recent improvements in implant conception (modular prosthesis) and a better understanding of physiological shoulder mechanisms should improve the functional results of this arthroplasty in the future.

Adult↗
PubMed1994

A rise in the intracellular Ca2+ concentration of isolated rat supraoptic cells in response to oxytocin.

1. Intracellular Ca2+ concentration ([Ca2+]i) was monitored in single cells isolated from adult rat supraoptic (SO) nuclei. The great majority of cells (85%) were neurones and most were immunoreactive to oxytocin or to vasopressin (AVP). 2. The resting [Ca2+]i of the majority (80%) of the neurones remained stable while 20% of the neurones displayed spontaneous [Ca2+]i oscillations which disappeared in low-Ca2+ (100 nM) EGTA buffer. 3. Addition of 100 nM oxytocin increased the [Ca2+]i in both stable and oscillating cells. Two types of responses were observed: (i) a sustained response with [Ca2+]i being maintained at an elevated level and (ii) a brief response with [Ca2+]i quickly returning to a near-resting level. Responses were reproducible, dose dependent and blocked with a specific oxytocin antagonist. 4. Removal of extracellular Ca2+ did not block the oxytocin response. In EGTA buffer, application of thapsigargin (200 nM) onto oxytocin-sensitive cells induced an increase in [Ca2+]i and inhibited the oxytocin response. These effects were not induced by other intracellular Ca2+ mobilizers such as tBuBHQ (see Methods) or caffeine. 5. In conclusion, half of the SO cells respond to oxytocin with a rise in [Ca2+]i. The effect is mediated by oxytocin receptors and results from release of Ca2+ from thapsigargin-sensitive stores.

Animals↗
PubMed1994

Synchronous development of spontaneous and evoked calcium-dependent properties in hypothalamic neurons.

The development of various related parameters was compared in hypothalamic neurons grown in primary culture. We measured: (i) low- and high-voltage-activated calcium currents; (ii) spontaneous and N-methyl-D-aspartate (NMDA)-induced fluctuations of intracellular calcium concentration; (iii) basal and NMDA- or potassium-evoked somatostatin release. Spontaneous calcium fluctuations appeared after 5 days in culture and increased progressively in amplitude and frequency over the next 8 days studied. Basal release of somatostatin was not detectable in 3 day-old cultures and reached a plateau at day 5. Responses evoked by exogenous stimulations (voltage-activated calcium currents, agonist-induced intracellular calcium rise and somatostatin release) appeared early in culture, increased in amplitude during 7-10 days and then stabilized. We conclude that, in hypothalamic neurons, the main neuronal functions develop in synchrony over a limited period of time.

Animals↗
PubMed1994

Yeast cells with a specific cellular make-up and an environment that removes acetaldehyde are prone to sustained glycolytic oscillations.

Glycolytic oscillations can be induced by adding glucose to starved Saccharomyces cerevisiae cells and, after a steady state has been established, cyanide. Transient oscillations or limit-cycle oscillations can be induced depending on the growth phase in which the cells are harvested. To find what causes these differences in the dynamic behaviour, we analyzed glycolytic enzyme activities at different growth phases. The hexokinase activity increased by a factor of three after growth substrate transition from glucose to ethanol; the other measured activities remained constant. Cyanide was found not only to block respiration, but also to trap acetaldehyde. Both cyanide actions appear necessary for the occurrence of sustained glycolytic oscillations.

Acetaldehyde↗
PubMed1994

Application of PCR site-directed mutagenesis for a rapid and accurate detection of mutation 3500 (Arg-->Gln) of human apolipoprotein B-100.

A rapid detection of the Arg3500-->Gln mutation of human apolipoprotein B-100 is of particular interest because of its prevalence in familial forms of hypercholesterolemia. A simple procedure, based on amplification by polymerase chain reaction (PCR) and NlaIII endonuclease restriction cleavage, allows this diagnosis without ambiguity. By using two oligonucleotide primers carrying one mismatch each, two permanent restriction sites were generated in the normal allele, while one of them disappeared in the mutant allele. Thus, the two alleles can be differentiated by their specific N/aIII restriction profile.

Alleles↗
PubMed1994

Neurophysiological follow-up in two children with Creutzfeldt-Jakob disease after human growth hormone treatment.

A serial neurophysiological study has been performed of 2 children during the clinical course of Creutzfeldt-Jakob disease after human growth hormone (hGH) treatment. Evolution of the EEG pattern was typical: slow waves, periodic sharp wave complexes, then extinction. VEP components were moderately altered. BAERs performed in only 1 child were normal. The blink reflex (BR) showed an early alteration of the R1 component. The ERG exhibited early and profound anomalies. Pathological changes were obvious at the first recording, at the beginning of the second month after clinical onset: increase in peak latencies, morphological changes and important reduction of b wave amplitude (a/b amplitude ratio > or = 0.70; normal range 0.27-0.41). The ERG was completely absent a few months later. These results are compared with the similar retinopathy described in CJD- or scrapie-infected rodents. In the 2 children, pathological changes in ERG and in BR were obvious several months before the development of the typical EEG pattern. Therefore, early ERG and BR recording can be helpful in the diagnosis of CJD, especially in this ataxic form following hGH treatment.

Blinking↗
PubMed1994

Evidence for connections between a discrete hypothalamic dorsochiasmatic area and the supraoptic and paraventricular nuclei.

In order to check the existence of direct or indirect connections between the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei, four retrograde traces were iontophoretically injected into these nuclei. The small injection sites were restricted to parts of the SON and PVN, enabling the identification of afferent neurons localized in their immediate vicinity. The tracer injections into any of these hypothalamic nuclei resulted in conspicuous labeling of cells gathered dorsally to the optic chiasma and the optic tract. This neuronal population was tentatively called dorsochiasmatic area. Double retrograde tracers injections into the ipsilateral SON and PVN gave evidence for some neurons containing both tracers in this dorsochiasmatic area. Otherwise, labeled parvocellular neurons were occasionally found in one PVN, after injecting retrograde tracer into either the ipsilateral SON or the contralateral PVN. As few connections exist between the four magnocellular nuclei, the dorsochiasmatic area connected with both the ipsilateral SON and PVN could play an important role in regulating the oxytocin and/or vasopressin systems.

Amidines↗
PubMed1994

Evidence for reciprocal connections between the dorsochiasmatic area and the hypothalamo neurohypophyseal system and some related extrahypothalamic structures.

In the preceding article, a dorsochiasmatic area (DCh) was described that projects to both paraventricular (PVN) and supraoptic (SON) nuclei. The main afferents of the DCh, revealed by local injections of retrograde tracers, are the hypothalamic PVN and SON, lateral septal nuclei (LSV and SHy), bed nuclei of the stria terminalis (BST), anteroventral third ventricle region, particularly the median preoptic nucleus (MnPO), the subfornical organ, medial preoptic areas, arcuate hypothalamic nucleus, ventromedial hypothalamic nuclei, paraventricular thalamic nucleus, and, more caudally, several structures of the posterior hypothalamus and mesencephalon. The relations between DCh and BST, LSV, SHy, or MnPO appeared reciprocal. In view of their reciprocal relationships with the hypothalamo-neurohypophyseal system and some of their related extrahypothalamic structures, the DCh might be involved in the regulation of the vasopressin (AVP) and/or oxytocin (OT) systems, or in reproductive behavior.

Afferent Pathways↗
PubMed1994

Fluoroquinolone use and fluoroquinolone resistance: is there an association?

In an assessment of potential risk factors for nosocomial infections caused by fluoroquinolone-resistant gram-negative organisms, 68 patients who developed a nosocomial infection caused by a fluoroquinolone-resistant gram-negative bacillus were compared with 191 patients who developed a nosocomial infection caused by a fluoroquinolone-susceptible gram-negative bacillus. A history of previous infection, immunosuppression, prior receipt of fluoroquinolones, and hospitalization on the burn unit were independent risk factors. Except for immunosuppression, the same risk factors were identified when the 50 patients whose isolates were resistant to fluoroquinolones, aminoglycosides, and beta-lactam antibiotics were compared with the 95 patients whose isolates were susceptible to all of these classes of antimicrobial agents. The identification of hospitalization on the burn unit as a risk factor was attributable to an outbreak of infections caused by a resistant strain of Pseudomonas aeruginosa during the study period. The occurrence of nosocomial outbreaks and the selective pressure of fluoroquinolone use were the main exogenous risk factors involved in the emergence of resistance to fluoroquinolones.

Adolescent↗
PubMed1994

Pseudomonas aeruginosa outbreak in a burn unit: role of antimicrobials in the emergence of multiply resistant strains.

An environmental survey and a cohort study were done to analyze an outbreak of infections in a burn unit caused by a serotype O:11 and a multidrug-resistant serotype O:12 Pseudomonas aeruginosa. The P. aeruginosa O:11 outbreak was controlled by eradicating an environmental source, contaminated hydrotherapy equipment. To assess risk factors for infections caused by P. aeruginosa O:12, 15 infected burn patients were compared with 32 noninfected burn patients hospitalized during the outbreak. Patients had similar extent, severity, location, and care of burn injuries, exposure to invasive procedures, and past history of P. aeruginosa infection. Prior treatment with ceftazidime (3 g/day) was the only independent risk factor for P. aeruginosa O:12 infection. The outbreak was controlled by increasing the daily administration of ceftazidime from 3 to 6 g and by a reinforcement of isolation precautions.

Adult↗
PubMed1994

Is there any indication for an intracardiac defibrillator for the treatment of atrial fibrillation?

The experience gained using intracardiac cardioverter defibrillators for the treatment of ventricular arrhythmias has prompted the development of an automatic atrial defibrillator capable of detecting and automatically terminating atrial fibrillation (AF). Experimental studies in sheep have shown that it is possible to terminate AF with energies ranging from < 1 to 7 joules [J], using biphasic shocks. The best electrode configuration using intracardiac catheters and/or a subcutaneous patch was two catheters, one in the right atrium and the other in the coronary sinus. Current studies in man focus on the answers to three questions. First, can the experimental results of atrial defibrillation derived from healthy anesthetized sheep without spontaneous AF be extrapolated to AF in man with areas of fibrosis within the atria and/or underlying heart disease in 80% of cases? Preliminary studies in man suggest that cardioversion of AF of short duration is feasible using a mean energy of 2 J. Second, are these energies well tolerated in an awake nonsedated patient? Energies < 1 J were well tolerated, but pain resulting from higher energies needs further investigation. Third, is low-energy atrial defibrillation safe, i.e., is there a risk of ventricular arrhythmias induced by an atrial shock? Experimental results in sheep have shown that the risk of R wave synchronized shock to induce ventricular arrhythmias was only present when the preceding RR interval was shorter than 300 msec. The risk of proarrhythmia in man is undergoing evaluation and must be sufficiently low (< 0.1) before sanctioning implantation of a stand-alone (without associated ventricular defibrillator) automatic atrial defibrillator. Preliminary data on 1212 shocks showed no proarrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Plasma amino acid and protein concentrations in infants fed human milk or a whey protein hydrolysate formula during the first month of life.

The aim of the study was to compare growth parameters, biochemical indices of protein metabolism and plasma amino acid concentrations in infants fed either human milk (n = 12) or a whey protein hydrolysate formula (n = 13) during the first month of life. Growth and gain in skin fold thickness were similar in both groups whereas serum protein concentration was significantly decreased (57.4 +/- 3.9 versus 61.2 +/- 2.9 g/l) in the infants fed the whey hydrolysate formula. The discrepancies between the plasma amino acid pattern of the whey hydrolysate formula group and that of the human milk group lessened during the first month. Nevertheless, at a mean age of 33 days the plasma threonine concentration remained twice as high and the plasma tyrosine, phenylalanine and proline concentrations were significantly lower in the whey hydrolysate formula group than in the human milk group. Thus, compared with breast-fed infants, growth and most of the biological indices of protein metabolism were satisfactory in infants fed during the first month of life on a whey protein hydrolysate formula. Nevertheless, the decrease in total plasma protein concentration needs to be confirmed in a larger cohort of infants. In addition, further research is necessary to investigate the possible ways of reducing the hyperthreoninemia and preventing other plasma amino acid disturbances since it would be desirable to obtain plasma amino acid levels similar to those of breast-fed infants.

Amino Acids↗
PubMed1994

Comparison of phenotypic methods and DNA hybridization for detection of methicillin-resistant Staphylococcus aureus.

One hundred thirty-eight Staphylococcus aureus isolates from patients with severe staphylococcal infections were collected in 15 French hospitals. Detection of the mec gene was performed by dot blot hybridization with a specific DNA probe. Dot blot results were used to characterize the isolates as methicillin susceptible (77 isolates) or resistant (61 isolates). The isolates were screened for methicillin resistance by an agar spread method on Mueller-Hinton plates containing oxacillin (2 and 10 micrograms/ml) and were incubated at 37 degrees C, with 10(8) CFU as the inoculum. MICs of oxacillin and methicillin were determined by the agar dilution method on Mueller-Hinton plates without NaCl, by using 10(5) CFU per spot, after 24 and 48h of incubation at 30 or 37 degrees C. Moderately elevated MICs were found for 20 isolates (14.5%). The mec gene was detected in six (30%) of the isolates expressing a low level of resistance to methicillin and/or oxacillin. As determined by comparison with probe hybridization results, the spread plate method with oxacillin at 2 micrograms/ml was more sensitive (sensitivity, 100%) and specific (specificity, 100%) than agar dilution with either methicillin or oxacillin in identifying methicillin resistance or susceptibility. Determinations of methicillin and oxacillin MICs by the agar dilution method had a specificity of 99 to 100% depending on the conditions of incubation, but the sensitivity was below 85% whatever the duration or temperature of incubation.

DNA, Bacterial↗
PubMed1994

Genetic polymorphism of apolipoprotein E in Caucasian alcoholic cirrhotics.

Steatosis is the most common although inconstant hepatic lesion induced by chronic alcohol consumption. Alcoholic cirrhosis is found in only 20 to 30% of chronic alcohol misusers, which points to the influence of both environmental and genetic factors. Apolipoprotein E (apo E) presents an important polymorphism with three common alleles, epsilon 4, epsilon 3 and epsilon 2. Its modulation role on triglyceride-rich lipoproteins and cholesterol-containing lipoproteins is linked with its interaction with cellular specific receptors. This work aims at studying a possible correlation between apo E polymorphism and alcoholic cirrhosis. The three common alleles were identified by enzymatic amplification (PCR) of genomic DNA from blood samples and analysis of restriction profiles. The distribution of alleles and genotypes was performed in 35 Caucasian cirrhotic patients (medium age 57 years) and compared with the usual distribution of apo E phenotypes in European Caucasian populations. The results show lower epsilon 4 and epsilon 2 allele frequencies and higher epsilon 3 allele frequency in Caucasian alcoholic cirrhotics.

Adult↗