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Biomedical subjects

R Eberhart

Publications and source records attributed to R Eberhart.

9 recordsLinked to original sources
PubMed2001

Bimanual haptic workstation for laparoscopic surgery simulation.

Realistic laparoscopic surgical simulators will require real-time graphic imaging and tactile feedback. Our research objective is to develop a cost-effective haptic workstation for the simulation of laparoscopic procedures for training and treatment planning. The physical station consists of a custom-built frame into which laparoscopic trocars and surgical tools may be attached/inserted and which are continuously adjustable to various positions and orientations to simulate multiple laparoscopic surgical approaches. Instruments inserted through the trocars are attached to end effectors of two haptic devices and interfaced to a high speed PC with fast graphics capability. The haptic device transduces 3D motion of the two manually operated surgical instruments into slave maneuvers in virtual space. The slave instrument tips probe the simulated organ. Simulations currently in progress include: 1) Surface-only renderings, deformation, and haptic interactions with elements in the gall gladder surgical field; 2) Voxel-based simulations of the bulk manipulation of tissue; 3) laparoscopic herniorrhaphy. This system provides force feed-forward from the grasped tools to the contact tissue in virtual space, with deformation of the tissue by the virtual probe, and force feedback from the deformed tissue to the operator's hands.

Computer Graphics↗
PubMed2000

Dangers of sleepiness and inattention while driving.

Sleepiness occurs in almost everyone at some time during each day. If sleepiness becomes moderate to severe, it can have an impact on an individual's ability to perform tasks that are prolonged or require a high degree of concentration. Driving is a daily activity that usually involves repetitive behaviors over a prolonged period, and it may be adversely affected by an individual who is sleepy. Data from the Department of Transportation show that sleepiness and fatigue contribute to numerous accidents on the road. This article reviews information related to the effects of sleepiness on driving, the types of sleepiness, and some tools for assessing sleepiness.

Accidents, Traffic↗
PubMed1990

[Prevention of exogenous respiratory infection].

The exogenous respiratory infections have two transmission channels, the airborne and the handborne ways, and two entrance doors, tracheotomy and intubation. Indeed, most often, contamination of the oropharynx occurs prior to the bacterial pneumonia. These microorganisms are isolated on healthy carries, on linen, furniture, air-conditioning system and so on... Special precautions are recommended as disinfection or sterilization of ventilators equipment changing circuits every 48 hours, using sterile water in humidifiers, and rigorous aseptic technic for tracheal suctions. An experimental study shows that microorganisms present in the humidifier disseminate through the circuit with the airstream. Therefore septic isolation of patients with pneumonia and disinfection of the room after his departure are considered as essential measure of prevention.

Clinical Protocols↗
PubMed1989

The cholinergic system in developing cerebellum: comparative study of normal, hypothyroid and underfed rats.

To overcome the deficiencies of previous findings, the activities of choline acetyltransferase (ChAT) and acetylcholinesterase (AchE) were studied at very short age intervals to allow a more precise definition of the shape and timing of their developmental curves in normal, hypothyroid and underfed rats. In addition, AchE expression in developing cerebellum was studied histochemically in these three neurological models. When compared with structural findings in the literature, the results provide the following information on the normal and abnormal developing cholinergic system, related or not to cerebellar neurotransmission (1) AchE activity, unlike ChAT, can be considered as a good marker of the developing cholinergic archicerebellum. (2) ChAT and AchE are transiently expressed together in functionally noncholinergic Purkinje cells. In contrast with most regions of the central nervous system, the high ratio of ChAT to AchE activities in the early stage of cerebellar development suggests an enhanced synthesis of acetylcholine (Ach). The level of ChAT activity correlates with Purkinje cell size, supporting the concept of a neurotrophic role of Ach in early maturing macroneurons. (3) The archicerebellar cholinergic network appears to be relatively well preserved from undernutrition and, to an even greater extent, from hypothyroidism, compared to other systems of neurotransmission formed later and more widely distributed throughout the cerebellum. The presynaptic compartment seems to be more affected than the postsynaptic compartment. (4) In disagreement with some data in the literature, the abnormalities induced by both abnormal thyroidal and nutritional states were found to be irreversible.

Acetylcholinesterase↗
PubMed1981

Effect of various degrees of systemic arterial hypertension on acute canine myocrdial ischemia.

There is continuing uncertainty about the effects of various degrees of systemic arterial hypertension on myocardial ischemia. In 46 open-chest anesthetized dogs, intramural carbon dioxide tension (PmCO2) was measured directly with a mass spectrometer during repetitive 10-min coronary artery occlusions separated by 45-min periods of reflow. During each occlusion, transmural regional myocardial blood flow (RMBF) in the ischemic area was quantitated with the injection of radioactive microspheres (7-10 micrometers diam). In all dogs the increase in PmCO2 from before to 10 min after the first occlusion (delta PmCO2) exceeded that during subsequent occlusions. In those dogs in which systemic arterial hypertension was not produced (controls), delta PmCO2 during the third occlusion was similar to that during the second occlusion. When phenylephrine was administered during the third occlusion to increase systemic arterial pressure mildly (diastolic pressure 95-115 mmHg), RMBF to the ischemic myocardium was unchanged, and the severity of myocardial ischemia was reduced, as reflected by a fall in delta PmCO2. When diastolic pressure was elevated moderately (116-140 mmHg), RMBF was augmented, but the extent of myocardial ischemia was neither diminished nor worsened. In contrast, when diastolic pressure was increased markedly (greater than 140 mmHg), myocardial ischemic injury was intensified (as reflected by an increase in delta PmCO2) even though RMBF rose significantly. Thus, in the dog with acute coronary artery occlusion, an increase of systemic arterial pressure exerts an influence on the severity of myocardial ischemic injury that is related directly to the magnitude of systemic arterial hypertension: a mild increase of pressure reduces ischemic injury, a moderate increase exerts no consistent effect on ischemia, and a marked increase worsens ischemic injury.

Acute Disease↗