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Biomedical subjects

R Morin

Publications and source records attributed to R Morin.

At least 19 recordsLinked to original sources
PubMed2002

Conducting, semiconducting and insulating objects observed by low-energy electron holography.

To demonstrate the potential of low energy in line projection holography, we study the reconstruction of the experimental holograms of three electrically different objects: a conducting, a semiconducting and an insulating object. The reconstructions of these holograms provide meaningful results for a large range of magnification of the object. The comparison between the reconstructed images and the scanning electron microscopy (SEM) micrographs of the same objects shows that the shapes and the dimensions of the reconstructed objects are identical to those obtained by conventional SEM. So, the simple assumptions needed to the reconstruction are justified. The reconstructions show a 2 nm resolution and appear superior than the best obtained SEM micrographs, when available. We also show some limitations of the reconstruction process. We point out that both numerical artifacts and experimental conditions are responsible for these limitations.

Journal Article↗
PubMed2002

Improved low energy electron projection in-line holograms reconstruction: application to the holograms of a tungsten tip.

A modification of the classical calculation algorithm is presented which allows to minimize the effect of the long range oscillations created by the twin object in the reconstruction process of in-line holograms obtained by low energy electron projection microscopy. The reconstructed shapes of a tungsten tip, observed with different magnifications are shown.

Journal Article↗
PubMed2002

Mandelic acid condensation polymer: novel candidate microbicide for prevention of human immunodeficiency virus and herpes simplex virus entry.

Presently marketed vaginal barrier methods are cytotoxic and damaging to the vaginal epithelium and natural vaginal flora when used frequently. Novel noncytotoxic agents are needed to protect men and women from sexually transmitted diseases. One novel candidate is a mandelic acid condensation polymer, designated SAMMA. The spectrum and mechanism of antiviral activity were explored using clinical isolates and laboratory-adapted strains of human immunodeficiency virus (HIV) and herpes simplex virus (HSV). SAMMA is highly effective against all CCR5 and CXCR4 isolates of HIV in primary human macrophages and peripheral blood mononuclear cells. SAMMA also inhibits infection of cervical epithelial cells by HSV. Moreover, it exhibits little or no cytotoxicity and has an excellent selectivity index. SAMMA, although not a sulfonated or sulfated polymer, blocks the binding of HIV and HSV to cells by targeting the envelope glycoproteins gp120 and gB-2, respectively, and also inhibits HSV entry postattachment. SAMMA is an excellent, structurally novel candidate microbicide that warrants further preclinical evaluation.

Antiviral Agents↗
PubMed2001

Imaging charged objects using low-energy-electron coherent beams.

The microscopic shapes, unobservable by conventional electron optics, of objects surrounded by electrostatic fields are observed. The method directly uses electron-coherent-beam imaging concepts and is successfully applied to recently developed low-energy-electron projection holography. Experimental demonstrations on objects charged in a controlled way like a biased metallic tip as well as on a self-charging insulator object are shown.

Journal Article↗
PubMed2000

The filmless radiology reading room: a survey of established picture archiving and communication system sites.

The purpose of this study was to survey radiologists experienced in soft-copy diagnosis using computer workstations about their current reading room environment, their impressions of the efficacy of their reading room design, and their recommendations based on their experience for improvement of the soft-copy reading environment. Surveys were obtained from radiologists at seven sites representing three major picture archiving and communication system (PACS) vendors throughout the world that have had extensive experience with soft-copy interpretation of radiology studies. The radiologists filled out a detailed survey, which was designed to assess their current reading room environment and to provide them with the opportunity to make suggestions about improvement of the PACS reading rooms. The survey data were entered into a database and results were correlated with multiple parameters, including experience with PACS, types of modalities interpreted on the system, and number of years of experience in radiology. The factors judged to be most important in promoting radiologist productivity were room lighting, monitor number, and monitor brightness. Almost all of the radiologists indicated that their lighting source was from overhead rather than indirect or portable light sources. Approximately half indicated they had the capability of dimming the brightness of the overhead lighting. Most radiologists indicated that they were able to adjust room temperature but that they did not have individual temperature controls at their workstations. The radiologists indicated that the most troublesome sources of noise included background noise, other radiologists, and clinicians much more than noise from computer monitors, technologists, or patients. Most radiologists did not have chairs that could recline or arm rests. Most did have wheels and the capability to swivel, both of which were judged important. The majority of chairs also had lumbar support, which was also seen to be important. Radiologists commonly adjusted room lighting and their reading chair, but rarely adjusted room temperature or monitor brightness. The median number of hours spent at the workstation before taken a "break" was 1.5. Common recommendations to improve the room layout included compartmentalization of the reading room and availability of the hospital/radiology information system at each workstation. The survey data suggest several areas of potential improvement based on radiologists' experience. Optimization of soft-copy reading room design is likely to result in decreased fatigue and increased productivity.

Attitude of Health Personnel↗
PubMed1997

Vasomotor instability preceding tilt-induced syncope: does respiration play a role?

This study aimed to determine whether alterations in cardiovascular dynamics before syncope are related to changes in spontaneous respiration. Fifty-two healthy subjects underwent continuous heart rate (HR), arterial blood pressure (BP), and respiratory measurements during 10-min periods of spontaneous and paced breathing (0.25 Hz) in the supine and 60 degrees head-up tilt positions. Data were evaluated by power spectrum and transfer function analyses. During tilt, 27 subjects developed syncope or presyncope and 25 remained asymptomatic. Subjects with tilt-induced syncope had significantly greater increases in low-frequency (0.04-0. 15 Hz) systolic BP, diastolic BP, and HR power during tilt than the asymptomatic subjects (P </= 0.01). This difference was present during spontaneous but not paced breathing. However, average tidal volume, respiratory rate, minute ventilation, proportion of breaths below 0.15 Hz, and low-frequency respiratory power during tilt did not differ between syncopal and nonsyncopal subjects. Transfer magnitudes between low-frequency respiration and BP, and between BP and interbeat interval, were also similar between groups. Thus vasomotor instability before syncope is not related to alterations in respiration or the cardiovagal baroreflex but may reflect oscillating central sympathetic outflow to the vasculature.

Baroreflex↗
PubMed1996

Age-related alterations in the fractal scaling of cardiac interbeat interval dynamics.

We postulated that aging is associated with disruption in the fractallike long-range correlations that characterize healthy sinus rhythm cardiac interval dynamics. Ten young (21-34 yr) and 10 elderly (68-81 yr) rigorously screened healthy subjects underwent 120 min of continuous supine resting electrocardiographic recording. We analyzed the interbeat interval time series using standard time and frequency domain statistics and using a fractal measure, detrended fluctuation analysis, to quantify long-range correlation properties. In healthy young subjects, interbeat intervals demonstrated fractal scaling, with scaling exponents (alpha) from the fluctuation analysis close to a value of 1.0. In the group of healthy elderly subjects, the interbeat interval time series had two scaling regions. Over the short range, interbeat interval fluctuations resembled a random walk process (Brownian noise, alpha = 1.5), whereas over the longer range they resembled white noise (alpha = 0.5). Short (alpha s)- and long-range (alpha 1) scaling exponents were significantly different in the elderly subjects compared with young (alpha s = 1.12 +/- 0.19 vs. 0.90 +/- 0.14, respectively, P = 0.009; alpha 1 = 0.75 +/- 0.17 vs. 0.99 +/- 0.10, respectively, P = 0.002). The crossover behavior from one scaling region to another could be modeled as a first-order autoregressive process, which closely fit the data from four elderly subjects. This implies that a single characteristic time scale may be dominating heartbeat control in these subjects. The age-related loss of fractal organization in heartbeat dynamics may reflect the degradation of integrated physiological regulatory systems and may impair an individual's ability to adapt to stress.

Adult↗
PubMed1990

[Young and economically precarious: an analysis of the situation of couples].

Changes in the economic status of young married and unmarried couples in Canada are examined for the period 1960-1989. The impact of the economic recession created by the restructuring of the economy in the early 1980s on the income of the young is analyzed. The authors investigate the impoverishment of young couples and compare it "with the evolution of income among older couples and analyze the impact of various factors, [such] as job stability, wage level and relative contribution of both partners." (SUMMARY IN ENG AND SPA)

Age Factors↗
PubMed1990

Hyperbaric oxygen effect on active Na+ transport across isolated toad skin.

The effect of hyperbaric oxygen (HBO) on Na+ transport across the isolated toad (Bufo marinus) skin was studied by measuring the transepithelial short-circuit current (ISC) and resistance (R) at 5, 8, and 10 ATA PO2 and 15 ATA normoxia during steady state conditions. The imposition of 5, 8, and 10 ATA PO2 for 2 h resulted in 45, 52, and 85% decrease in ISC, respectively. This decrease in ISC was always accompanied by an increase in R. When amiloride (10(-4) M) was added to the bathing medium, ISC decreased to zero within 15 min regardless of the PO2 level, indicating that the HBO-induced decrease in ISC is caused by an inhibition of amiloride-sensitive Na+ transport. Addition of both superoxide dismutase (SOD) and catalase to the medium bathing both sides of the skin markedly attenuated the HBO effect on ISC and R. Applying HBO to the serosal or mucosal surface independently produced similar effects on ISC. However, the presence of antioxidant enzymes (SOD and catalase) with 10 ATA PO2 prevented the toxic HBO effect only from the serosal side; no protection by these antioxidant enzymes was observed from the mucosal side. These findings are consistent with a view that free radicals are involved in the HBO-induced inhibition of ISC. However, further studies involving the site(s) of radical generation as well as site(s) of toxic action are needed to understand the cellular and molecular mechanism of HBO toxicity.

Amiloride↗
PubMed1990

[Value of the administration of trimetazidine associated with hemodilution in the treatment of sudden deafness. Report of a multicenter study].

Sudden deafness is a medical emergency, for which etiopathology is ill-known and no therapeutic consensus exists. This study is aimed at demonstrating that a greater audiometric gain can be achieved if trimetazidine, a major cellular anti-ischemia agent, is associated with hemodilution, than when the treatment is based on hemodilution only. 42 patients suffering from sudden deafness were all treated with hemodilution before their 7th day of deafness, half of them being given 3 tablets of trimetazidine daily in addition and the other half placebo, during one month. The results of this double-blind trial demonstrate an additional audiometric gain of 10% in the trimetazidine group for all frequencies, as well as a higher percentage of total recovery, ie. 63% vs. 47% in the placebo group. No particular sensitivity to treatment was noted according to the shape of the audiometric curve or in the case of initial cophosis, known to be of poor prognosis. The statistic significance was not established due to the small number of cases. The association of trimetazidine and hemodilution therefore seems to be an interesting therapeutic approach for sudden deafness, owing to the clinically appreciable audiometric improvement we have noted.

Adult↗
PubMed1990

[Transposition of the temporal muscle and surgery of the middle third of the face. Technic, indications and results].

The authors reemploy the technique using the temporal muscle to fill in large surgical cavities after tumoral surgery of the middle 1/3 of the face. The purpose of this technique is to prevent crust formation after radiotherapy, and to improve esthetic results by preventing further cutaneous retraction. They expose their own technique, the results and the indications from 8 cases.

Adult↗
PubMed1990

Influence of cholesterol oxides on endocytosis of cultured endothelial and smooth muscle cells.

Human umbilical vein endothelial cells and rabbit aortic smooth muscle cells in culture were incubated for intervals up to 24 hrs with varying concentrations of cholesterol, 7-ketocholesterol, 25-hydroxycholesterol, cholestane-3 beta,5 alpha,6 beta-triol or cholesterol-5 alpha, 6 beta-epoxide. Endocytosis, as measured by uptake of horseradish peroxidase (HRP), was inhibited in a dose and time dependent manner in both endothelial and smooth muscle cell cultures by cholestane-3 beta,5 alpha,6 beta-triol and 25-hydroxycholesterol. Inhibition by 7-ketocholesterol in endothelial cells occurred only at higher concentrations, and cholesterol and cholesterol epoxide showed no significant inhibitory effects. The viability of the cells exposed to the cholesterol oxides at the concentrations that inhibited the uptake of HRP was not changed. Cholesterol oxides induce functional endothelial injury, not morphologically apparent, which may be involved in atherogenesis.

Animals↗
PubMed1989

[New prospects in the treatment of vertigo].

Vertigo results from sensory conflicts that are usually intralabyrinthine or between two labyrinths. Symptomatic treatments rests on the reduction of these conflicts by vestibuloplegic drugs. However, this treatment should not last for more than 48 or 72 hours since in established vestibular lesions central compensation demands that the centres be informed. The use of sedative drugs in vertigo, therefore, should be reduced, and vestibular rehabilitation is recommended in most cases. Only Meniere's disease escapes this rule, being a self-limited process.

Acute Disease↗
PubMed1989

[Giant cell tumor of the temporal bone. Clinical study of a case. Histologic and therapeutic remarks].

A case of giant cell tumor of the temporal bone is reported. The surgical difficulties encountered in this case are presented and therapeutic modalities for this tumor, consisting of radical surgery and post operatoire radiotherapy, one defined and discussed. Comments are made concerning this rare tumor location, its occurrence in young adults, and difficulties in establishing a histologic diagnosis.

Adult↗
PubMed1988

[Repair of deglutition troubles after partial surgery of the pharyngolarynx with injection of collage. Apropos of 9 cases].

The authors report their experience treating nine patients with swallowing disorders following partial surgery of the laryngo-pharynx. GAX collagen (Phonagel), resistant to collagenase was injected into the laryngeal structures to protect the trachea, yielding a satisfactory long term result. A description of the injection technique is given particularly with functional reconstructive laryngectomies and hemipharyngolaryngectomies. The results concerning functional improvement and weight gain are evaluated over a five month period.

Collagen↗
PubMed1988

Effect of a pulsed magnetic field on tumoral C3H/Bi female mice.

Female C3H/Bi mice develop spontaneous viral mammary carcinoma which can metastasize to the lungs. Two hundred and forty tumoral mice were either exposed to a toroïdal pulsed magnetic field, 12 Hz, 100 Hz or 460 Hz in frequency or used as controls. The exposure was mainly done 10 min. a day, 3 days a week, or 30 minutes once a week from about 2 to 3 weeks after the appearance of the tumors until death. In comparison with the controls, the exposed mice showed lighter spleens and lungs; this last observation could mean fewer pulmonary metastases. The weight of the tumors has been found lighter for 460 Hz MF, not changed for 100 Hz MF, heavier for 12 Hz MF, but lifespans were not altered by the exposure.

Animals↗