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Biomedical subjects

D Glauser

Publications and source records attributed to D Glauser.

9 recordsLinked to original sources

Robotic three-dimensional positioning of a stimulation electrode in the brain.

Functional stereotactic cerebral operations are currently performed with straight electrodes. After physiological exploration, correction of the initial target is frequently necessary and requires multiple penetrations of the brain. This paper describes a robotic three-dimensional electrode probe that can reach targets located within a cylindrical volume from a single approach trajectory. It has been mounted on the neurosurgical robot Minerva, and includes a string electrode, which can protrude out of the side window of a straight cannula and offers a high intrinsic accuracy of 0.25 mm. A simple man-machine interface allows the surgeon to select reference and target points and to activate the probe from a graphics workstation. This paper also analyzes the accuracy of the probe as well as of the whole operating system, food gelatin being used to simulate brain matter.

Brain↗

Genetic polymorphism of CCR5 gene and HIV disease: the heterozygous (CCR5/delta ccr5) genotype is neither essential nor sufficient for protection against disease progression. Swiss HIV Cohort.

Homozygous (delta ccr5/delta ccr5) and heterozygous (CCR5/delta ccr5) deletions in the beta-chemokine receptor 5 (CCR5) gene, which encodes for the major co-receptor for macrophage-tropic HIV-1 entry, have been implicated in resistance to HIV infection and in protection against disease progression, respectively. The CCR5/delta ccr5 genotype was found more frequently in long-term nonprogressors (LTNP) (31.0%) than in progressors (10.6%, p < 0.0001), in agreement with previous studies. Kaplan-Meier survival analyses showed that a slower progression of disease, i.e. higher proportion of subjects with CD4+ T cell counts > 500/microl (p = 0.0006) and a trend toward a slower progression to AIDS (p = 0.077), was associated with the CCR5/delta ccr5 genotype. However, when LTNP were analyzed separately, no significant differences in CD4+ T cell counts (p = 0.12) and viremia levels (p = 0.65) were observed between the wild-type (69% of LTNP) and the heterozygous (31.0%) genotypes. Therefore, there are other factors which play a major role in determining the status of nonprogression in the majority of LTNP. Furthermore, there was no evidence that the CCR5/delta ccr5 genotype was associated with different rates of disease progression in the group of progressors. Taken together, these results indicate that the CCR5/delta ccr5 genotype is neither essential nor sufficient for protection against the progression of HIV disease.

HIV Infections↗

Force feedback for virtual reality based minimally invasive surgery simulator.

This paper presents ongoing research towards an endoscopic surgery simulation system. Our specific application of interest is laparoscopic surgery. The goal is to conceive an endoscopic surgical training tool which allows to realistically simulate the interactions between one or several surgical instruments and the gastrointestinal organs in a virtual reality based environment. An artificial patient is being developed into which endoscopic surgical instruments can be inserted to operate upon virtual organs displayed on a video monitor. In order to achieve a faithful and precise simulation, not only a realistic graphical representation of the organic tissue and its behavior is needed, but also the forces and moments on the surgical instruments encountered during an operation are required to be simulated. The laparoscopic surgery simulator must therefore provide force feedback through the endoscopic instruments manipulated by the surgeon. This paper details the mechanical design of the force feedback mechanisms and addresses some of the technical challenges of this project.

Computer Simulation↗

Neurosurgical robot Minerva: first results and current developments.

We describe the development and approach to clinical application of the neurosurgical robot Minerva, including the mechanical structure of the robot and the software developed to perform intracranial neurosurgical operations with accuracy, smoothness, and safety. The first eight operations have been undertaken on patients requiring stereotactic brain biopsy. We describe the ongoing developments, including improved sterilization features, force sensors, nonlinear electrostimulation probe, and implantation of living encapsulated cells, all of which have entered a test phase. The goals are increased safety and capability to perform simple three-dimensional operations. This research should ease the way for new complex operations that are difficult to perform manually today.

Biopsy↗

Robot for CT-guided stereotactic neurosurgery.

At the 1989 meeting of the World Society for Stereotactic and Functional Neurosurgery in Maebashi, the authors presented the concept and design of a stereotactic neurosurgical robot. The first prototype has now been completed and has entered clinical testing. The characteristics are as follows. The robot is positioned behind the CT scan and operates inside the CT gantry. It is linked to the CT table and moves freely along its longitudinal axis, allowing for intraoperative scanning at any cranial level. The patient's body rests on the CT table, but the stereotactic headframe is fixed to the robot, allowing precise measurements of the head position under stereotactic conditions. During scanning, each CT slice appears immediately on the robotic workstation for selection of target and trajectory. In addition to the tool for automatic penetration of the skin, skull, and meninges, the robot is able to handle two other stereotactic instruments and to perform a complete stereotactic procedure without physical intervention by the physician. So far, depth electrodes and biopsy instruments have been developed for use by the robot. Since all parts of the robot were designed solely for stereotactic neurosurgery, integration of safety aspects was optimized. The first operations using an aspiration biopsy probe were successfully performed on 2 patients with malignant intracerebral cystic lesions on September 4, 1993.

Humans↗

Configuration of a robot dedicated to stereotactic surgery.

The design of a robot for functional stereotactic surgery which is under construction in our laboratory is described. The main features include operation inside the computed tomographic (CT) scanner, the possibility of intraoperative CT scanning and complete handling of the stereotactic probes by the robot.

Brain Diseases↗

Prescribing patterns in an outpatient psychiatric clinic.

Prescribing patterns were studied in a psychiatric outpatient clinic. Psychiatrists tended to prescribe large quantities of antidepressants or other drugs. In contrast, the daily doses for antidepressants and neuroleptics were often too low. Significant variations were noted between three outpatient clinics in the choices among a various psychotropic drugs from a given therapeutic group.

Adolescent↗

Stability of DSM-III-R diagnoses: study of a case register.

We studied the diagnostic stability and the factors associated with it in 1,443 psychiatric patients with multiple admissions for a period of 45 months. We successively considered the whole population, the psychotic and then the schizophrenic patients. Demographic and DSM-III-R diagnostic information was collected on a computerized database. During the observation period, 1,443 patients were hospitalized twice or more. Diagnostic stability ranged from 34 to 86%. Psychotic disorder was the most stable, whereas adjustment and anxiety disorders were the least stable. Among schizophrenic patients, higher stability appeared for residual and disorganized types (83 and 71%, respectively). Statistical analysis did not show any variable associated with change, apart from the diagnoses themselves. The reasons that could explain changes are discussed, as well as the clinical consequences of these shifts.

Adult↗

[Comparison between Swiss and foreign patients characteristics at the psychiatric emergencies department and the predictive factors of their management strategies].

UNLABELLED: Many studies are searching clinical and social-demographic predictive factors of the management options in psychiatric emergency. The greater part of these researches are published in US and are seeking about patients and about conditions of psychiatric practice different of the European circumstances. Such differences have motivated us to perform a comparison between the characteristics of the native Swiss and of the foreign patients in the psychiatric emergencies. The other aim of the study was to detect, if differences are proven, some predictive factors of their management strategies. This study describes the social-demographic and clinical characteristics of a sample of 1 028 unduplicated consultations and investigates possible relationships between these clinical characteristics and different management strategies, with a particular focus on the foreign patients, covering 46.5% of all consultations. Because quite half of the psychiatric emergency visits occur with foreigners, it plays a potentially important role in searching the disparities in diagnosis and management. To verify these differences, we studied two specific questions: 1) are there nationalities differences in diagnosis with respect to the Swiss native population, and 2) are there nationality differences in management of patients visiting a psychiatric emergency service? METHODOLOGY: Demographic and clinical data were obtained prospectively from the psychiatric emergency service of Geneva, located in the county general hospital, during a 13 weeks period. The study involved all patients aged between 18 and 65 years, inhabitants of county of Geneva-Switzerland, presented at the psychiatric emergency service of the general hospital. To limit the bias of screening the chronic patients, we have included only once, at the first examination, the patients with more than one emergency consultation in the considered interval. RESULTS: As a general trend, the probability for the foreign patients to consult the emergency psychiatrist is greater than for the Swiss natives: OR=1.44, p=0.000. The social-demographic factors show significant differences between the foreigners and Swiss population: the immigrating population is younger, more active and clustered to a familial structure. Despite the availability and use of the same clinical criteria, foreign patients are disproportionately differently diagnosed, with less alcohol abuse (14.7% for foreigners versus 23.9% in the Swiss population), less personality disorders (8.1% versus 13%), more affective disorders (54.7% versus 43%) and more anxious disorders (18.4% versus 12.3%). Furthermore, on the sum of all diagnoses, the single statistically significant difference in management is found in respect to the recommendation for a Short-term Therapeutic Centre , done more frequently for the foreigners: 15.5% versus 11.3%. Some immigration-related predictive factors of diagnosis and management are found and detailed. DISCUSSION: The apparent habit of the foreigners to appeal to the hospital emergencies could be, at least partially, due to a minority or cultural factor: the patients seem to be easily appealing to a great hospital rather than to a territorial policlinic by failure to find a psychiatrist into the Swiss health network. This hypothesis is to be confirmed by further studies. The inexistence of significant differences in management of the patients with the same diagnosis between the two patient groups suggests the equality of resources spent for the two patient groups. The main methodological limit of this study consists of the gathering of different immigrated nationalities in a unique patient group in order to find, if any, significant differences in comparison to the Swiss patients, whereas may be matter of heterogeneous populations. CONCLUSION: These observations suggest that further researches are needed to clarify the decision-making process in diagnosis and patient management in psychiatric emergency department, especially for foreigners, and to distinguish different cultural groups rather than different nationalities. The reassessment of all patients with their clinical evolution and the allocated health resources could lead to the question on the relevance of health management decisions in psychiatric emergency circumstances, as well as to the question on the influence of the foreigner status on therapeutic decisions.

Adult↗