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Biomedical subjects

J M Brunetaud

Publications and source records attributed to J M Brunetaud.

At least 19 recordsLinked to original sources
PubMed2002

A resource server for medical training.

OBJECTIVES: We have developed a RESOURCE SERVER to collect and store various elements used by a professor during his lecture. METHODS: The server manages four types of objects: ELEMENTS, RESOURCES (set of elements referring to a given topic), INDEXES (to organize the resources for further search and use), and USERS (to identify providers, users, and access rights). If an ELEMENT s modified, the RESOURCE is automatically updated. RESULTS: An example (preparation of an anatomy lecture) explains how the RESOURCE SERVER works in three steps: organization of the training material, indexing, and retrieval. CONCLUSIONS: The RESOURCE SERVER will help instructors develop, update and share pedagogic resources for supporting their training courses, lessons and conferences. Moreover, these techniques, based on Internet technologies for easy handling of and access to these resources, allow local and distant access. Within the general framework of the French-speaking Virtual Medical University, the RESOURCE SERVER will represent an important link between data collection and its use in intelligent pedagogic training.

Computer Storage Devices↗
PubMed2001

Impact of a modelization of the task allocation problem on the design of a prescription management software for intensive care units.

After having studied the coordination in Intensive care Units we have proposed a dynamic model for improving coordination in respect of human control over the work. We have performed simulations for analysing the impact of different strategies on coordination and we have found that our task centred coordination model could be efficient to improve the health care actors coordination and the efficiency of care delivery. We have built a first prototype based on this model. This implementation uses Internet technologies.

Computer Simulation↗
PubMed2000

The French Virtual Medical University.

This paper is the description of a French Virtual Medical University based on the federation of existing or currently being developed resources in several Medical Schools in France. The objectives of the project is not only to share experiences across the country but also to integrate several resources using the New Information and Communication Technologies to support new pedagogical approaches for medical students and also for continuing medical education. The project includes: A virtual Medical Campus using secure access from several sites, The Integration of new interactive resources based on pedagogical methods, Implementation of new indexing and search engines based on medical vocabularies and ontologies, The definition of general and specific portals, the evaluation of the system for ergonomics and contents.

Computer-Assisted Instruction↗
PubMed1995

Sixty argon laser-assisted anastomoses in rats: macroscopic and histological studies.

The present in vivo study was undertaken to evaluate the patency rate and histological appearance of 30 venous anastomoses and 30 carotid anastomoses in Wistar rats using a laser. An argon laser was used with the following parameters: power, 100 mW; time, 3 seconds; continuous mode; spot, 200 microns (fluence, 950 J/cm2; irradiance. 320 W/cm2). The macroscopic appearance and patency rate were evaluated at different postoperative intervals (30 days and 60 days). In the venous group, the patency rate was 100% with no saccular pseudo-aneurysm. In the arterial group, the patency rate was 93% with three saccular pseudo-aneurysms and two thromboses. Histological studies noted slight and transitory modifications of the media in the arterial group. In the venous group, the modifications appeared under the endothelium. Since the procedure was similar in both groups, the lack of pseudo-aneurysm formation in the venous group can be explained by a lower intravascular pressure.

Animals↗
PubMed1995

Fluorescence of experimental endometriosis in rabbits, using tamoxifen-eosin association.

A major problem with endometriosis is the detection of microscopic and atypical lesions. An incomplete surgical eradication may lead to recurrence of the disease. This study aimed to investigate the diagnostic improvement of endometriosis by the use of tamoxifen-eosin induced fluorescence. The experimental study was performed on surgically induced endometriosis in the rabbit. Endometriosis was induced by grafting endometrium onto the broad ligament in 10 rabbits. After 5 weeks, the fluorescence of excised endometriosis was studied after systemic injection of tamoxifen and local application of eosin. Healthy peritoneal samples served as controls. The fluorescence of endometriotic foci was also compared with (n = 5) or without (n = 5) tamoxifen. Fluorescence excitation was carried out using a 150 W filtered lamp connected to an optical fibre. Fluorescence emission was measured using an optical fibre connected to a spectrofluorometer. Spectral analysis showed a specific fluorescence of endometriosis 72 h after systemic injection of tamoxifen and eosin application. This result is explained by binding to oestrogen receptors of tamoxifen which was protonized to form an ionic pair with eosin. Histological study of samples from the graft of endometrial tissue showed that experimental endometriosis had developed in eight out of the 10 rabbits. However, the fluorescence was not significantly different among the 10 rabbits. This observation was in accordance with previous studies in which endometriosis was confirmed by routine histological techniques or electron microscopy in 70-80% of cases. Consequently, the fluorescence of the two samples which did not present histological evidence of endometriosis indicates the presence of microscopic endometriotic foci.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Development and experimental in vivo validation of mathematical modeling of laser coagulation.

Most clinical procedures using the laser are based on thermal laser-tissue interactions. The treatment often consists of inducing damage of given degree and extent by heating the tissue. The aim of this study was to develop a model called HELIOS. The ability of HELIOS to predict thermal coagulation was evaluated by comparison with in vivo experimental results. Conversion of laser light in tissue was studied using the beam-broadening model. Temperature was described by the heat conduction equation solved using the finite difference method. The tissue denaturation was modeled by the Henriques equation leading to the determination of the damage coefficient omega. For a given set of laser and tissue parameters, HELIOS makes a graphic representation of coagulation necrosis and temperature evolution in tissue. HELIOS was validated by experimental studies in vivo on rat liver using a CW Nd:YAG laser, a CO2 laser, and an argon laser. For given sets of laser parameters, temperature measurements were performed using an infrared camera. Histological examinations were carried out on samples to quantify the depth of coagulation necrosis. Experimental data obtained in vivo were compared with those calculated using HELIOS and similar sets of parameters. The difference between the predicted temperature evolution on tissue surface and that measured by the infrared camera was < 5 degrees C in all cases. The difference between the predicted coagulation necrosis depth and the corresponding experimental one was < 10%. In conclusion, HELIOS allows good prediction of tissue temperature and coagulation necrosis.

Animals↗
PubMed1994

Determination of efficient parameters for argon laser-assisted anastomoses in rats: macroscopic, thermal, and histological evaluation.

The aim of this study was to determine efficient parameters for an argon laser (spot diameter = 200 microns) to obtain and reproduce vessel anastomoses. It was performed in two groups of Wistar rats. In the first group (89 Laser impacts on 10 carotids), the fluence was continuously adjusted from 30 to 3,000 J/cm2 in order to determine efficient sets of parameters (power from 90-200 mW, pulse duration from 0.1 to 5 seconds, pulsed or continuous mode). In the second group, 30 end-to-end carotid anastomoses were performed. The results were evaluated by macroscopic thermal, and histological studies. The second group proved the efficiency of the selected parameters. Vessel welding was obtained with 100 mW, 3 seconds, continuous mode (fluence = 950 J/cm2, irradiance = 320 W/cm2) for a mean temperature of 77 degrees C corresponding to collagen denaturation. In the second group the patency rate was 93% (28/30) with three pseudo-aneurisms and two thromboses. Histological studies noted slight modifications of the media.

Anastomosis, Surgical↗
PubMed1994

[Control of intensity of light coagulation by thermo-induced release of a fluorescent marker encapsulated in liposomes. In vivo/ex vivo preliminary study].

PURPOSE: The aim of this in-vivo/ex vivo study was to assess the possible use of temperature sensitive liposomes in an established model such as the liver as a new approach to monitor the temperature induced by a laser. METHOD: Temperature sensitive liposomes (DSPC: DiStearoylPhophatidyl-Choline: critical temperature: 55 degrees C) loaded with carboxy-fluoresceine were prepared by the Bancham procedure. These liposomes (1 ml solution) were injected to adult male wistar rats. Two hours later, the liver was exposed and irradiated with a 100 W Nd: YAG laser (single pulse mode, pulses ranging from 100 to 260 ms, spot diameter: 4 mm). Simultaneously, the surface temperature was recorded with a infrared thermographic camera (Aga). The fluorescence emission was then measured with a fluorescent imaging system (Hamamatsu). RESULTS: The dye was released in response to laser energy. The amount of the drug release increased linearly with increasing temperature in the range 42 to 60 degrees C. The estimated latency of release seems more related to the heating pattern (i.e. to laser parameters) than to the liposomes. CONCLUSION: This preliminary study assesses the possible use of laser-induced release of liposome-encapsulated dye to monitor tissue temperature and then thermal damage.

Animals↗
PubMed1993

Rationale for automatic scanners in laser treatment of port wine stains.

Laser therapy of port wine stains (PWS) is well established. However, the application of lasers to PWS treatment over the last decade has resulted in the use of many laser systems. The goal of this study is to describe the different laser parameters, treatment techniques, and delivery systems. Two methods, coagulation and microvaporization, are used to destroy the abnormal blood vessels. The coagulation method results in excellent treatment, but it requires careful control of laser parameters during the treatment process. Scanning devices can be utilized for this purpose. The microvaporization method, obtained with a pulsed dye laser, is restricted to PWS composed of small vessels since it is difficult to obtain a pulse longer than 450 microseconds. In addition, numerous retreatments are needed with the pulsed dye method. The initial assessment of the patient should contribute to an improvement in the choice of laser parameters and the outcome of treatment.

Adult↗
PubMed1993

Relation between skin surface temperature and minimal blanching during argon, Nd-YAG 532, and CW dye 585 laser therapy of port-wine stains.

Laser photocoagulation has proven to be valuable in the treatment of port-wine stains. In this application, the minimal blanching technique is used as an indicator of suitable dosage since it has been demonstrated that the immediate appearance a white mark is required to achieve permanent blanching a few months later. The objective of the investigations undertaken in this study was to correlate the temperature attained at the surface of port-wine stains with immediate blanching, upon irradiation with different laser fluences. A comparative study was performed using an argon laser (all lines), a 532 nm Nd:YAG and a 585 nm argon pumped dye laser. Surface temperature was studied using an infrared camera. Temperature was measured on 10 different port-wine stains using different fluences. Whitening threshold fluence was related to surface temperature. It appeared that whitening threshold fluence corresponded to a surface temperature of 53 degrees C (+/- 3 degrees C). The whitening threshold fluence was dependent on port-wine stains and wavelength. However, whitening threshold fluence remained lower for 532 nm and 585 nm and it correlated to the absorption curve of hemoglobin.

Hemangioma↗
PubMed1992

Endoscopic palliation for inoperable malignant dysphagia: long term follow up.

This prospective non-randomised trial of 128 selected patients with unresectable oesophageal or gastrooesophageal junction cancers aims to evaluate the initial relief of malignant obstruction by means of bipolar electrocoagulation for both circumferential and submucosal strictures of Nd:YAG laser for the other patients. A limited dilatation was performed initially if a small calibre endoscope was unable to pass through the stricture. Prompt and significant relief of dysphagia without complications was achieved in 83% of patients. Improved patients were retreated monthly during the follow up period. Radiotherapy was recommended when possible. Symptomatic relief of obstruction lasted 4.2 months on average and 76% of patients remained palliated until death. Monthly retreatment using the most appropriate endoscopic procedure for the tumour configuration and radiotherapy after endoscopic relief of obstruction seems to give the best palliation for patients with unresectable cancers of the oesophagus or gastrooesophageal junction.

Adenocarcinoma↗
PubMed1992

[Physical basis of therapeutic uses of lasers].

Therapeutic applications of lasers usually require different mechanisms of laser tissue interaction: the thermal interaction mechanism where light energy is converted into heat, the photochemical interaction mechanism where light induces chemical reactions, the mechanical interaction mechanism where light produces shock wave and the photoablative interaction mechanism where light energy produces desorption of tissue. The interaction mechanism depends on the choice of the laser parameters.

Humans↗
PubMed1992

[Future of medical lasers].

Whatever the medical field of application of lasers, their future is linked to research and to the realization of systems of automatization which will allow the development of "smart lasers". It will be linked to the improvement of imaging techniques and of medical computers, as well as to the development of new feedback systems; the wavelength and the laser beam dosimetry could then be automatically chosen depending on the aimed tissue and on the biophysical effect desired on the target (coagulation, vaporization, cutting, hyperthermia, photo-ablation). Practically, the future of lasers also depends on the elaboration of new peripheric systems and a better conception of new laser equipment. At last, clinical evaluation of such new surgical technologies with well adapted procedures, formation and information through specific teaching courses and seminars will help to the development of all new laser-technologies.

Education, Medical, Graduate↗
PubMed1992

[Proximal tubal recanalization by endoluminal laser probe. I. Anatomic results in the female rat].

To evaluate the cicatrization of the uterine horn after the recanalization by endoluminal laser probe, 50 white female rats of Wistar's race have been separated into two groups. The group 1 (nb = 10) had for aim to validated the procedure of obstruction. In group 2 (nb = 40), we performed the recanalization six weeks after the obstruction. Histologic samples were obtained 48 hours, 3 weeks and 6 weeks after treatment. In group 1, we found a complete obstruction in 70% of the cases, and a tight stenosis in 30% of the cases. In group 2, at 48 hour's control after the treatment by laser, we found a drill hole with a blackened look without parietal sequel in 80% of the cases. At 6 week's control, we found a normal lumen with a regeneration of the epithelioma in 85% of the cases. For energy deposition under 30 Joules, we found good results in 95% of the cases. Above 30 Joules, we always found bad results (5 cases on 5).

Animals↗
PubMed1992

[Proximal tubular recanalization by endoluminal laser. II. Functional results in the female rabbit].

To evaluate the function of the fallopian tube after a recanalization by endoluminal laser probe, 34 mature female New Zealand white rabbits have been separated into two groups. The group 1 (nb = 12) had for aim to validate the procedure of obstruction. In group 2 (nb = 22), we performed the recanalization six weeks after the obstruction. The female rabbits underwent a fertilization six weeks after the laser treatment. The results have been appreciated by the ratio nidation/ovulation. In group 1, we valided the procedure of obstruction. In group 2 twelve rabbits on thirteen have been fecundated in the treated tube.

Animals↗