Design of an active-passive device for human ankle movement during functional magnetic resonance imaging analysis.

Functional magnetic resonance imaging analysis has made major strides in recent years, both because of the development of new scanners and owing to magnetic resonance compatible systems that make it possible to stimulate parts of the human body during analysis. The significant gains in our knowledge of the brain that can thus be achieved justify efforts to construct machines with control circuits suitable for this purpose. This paper presents a magnetic resonance compatible mechatronic device with electropneumatic control that can be used to move one or both feet during functional magnetic resonance imaging analysis of the cerebral motor zones.

A combined robotic and cognitive training for locomotor rehabilitation: evidences of cerebral functional reorganization in two chronic traumatic brain injured patients.

It has been demonstrated that automated locomotor training can improve walking capabilities in spinal cord-injured subjects but its effectiveness on brain damaged patients has not been well established. A possible explanation of the discordant results on the efficacy of robotic training in patients with cerebral lesions could be that these patients, besides stimulation of physiological motor patterns through passive leg movements, also need to train the cognitive aspects of motor control. Indeed, another way to stimulate cerebral motor areas in paretic patients is to use the cognitive function of motor imagery.

Pneumatic interactive gait rehabilitation orthosis: design and preliminary testing.

Motor rehabilitation techniques based on passive movement of the lower limbs have been developed over the past 15 years. Gait training automation is the latest innovation in these techniques. This paper describes the design and development of a pneumatic interactive gait rehabilitation orthosis (PIGRO), as well as the first experimental results obtained with healthy subjects.

Experimental comparison between a Staffieri and a New Prototype tracheo-oesophageal valve.

A tracheo-oesophageal valve is used for the rehabilitation of patients who have lost vocal function due to a total laryngectomy. The valve is positioned in a surgically created fistula between the airway and the upper oesophagus at the level of the post-laryngectomy stoma. It permits passage of air from the trachea to the pharynx to permit speech, while it blocks the flow of secretions and food materials from the digestive tract to the airway.

Staffieri tracheo-oesophageal prosthesis for voice rehabilitation after laryngectomy: an evaluation of characteristics.

Experimental results on voice prostheses used for the rehabilitation of patients that have lost their vocal function after total laryngectomy are presented. The purpose is to evaluate the difference in aerodynamic behaviour between Staffieri voice prosthesis and other commercial valves (Groningen standard, Groningen low pressure, Panje, Provox). Two different equipments for flow-rate measurement were designed and built to compare the performance of the valves.

Assessment of the hepatic circulation in humans: new concepts based on evidence derived from a D-sorbitol clearance method.

D-Sorbitol (SOR) is safe, is easy to measure, and has an exceptionally high extraction ratio in the normal liver of 0.93+/-0.05 (mean+/-SD).

Dynamic behavior of the Provox and Staffieri prostheses for voice rehabilitation following total laryngectomy.

The present study evaluated the differences in aerodynamic behavior between the 1990 Provox and 1986 Staffieri voice prostheses for total laryngectomy patients. Both prostheses were submitted to in vitro laboratory testing to assess their aerodynamic behavior under different conditions of air flow through the valve and tracheal side pressure. In addition, six patients using the Provox and another six using the Staffieri prostheses were submitted to a dynamic study of phonation.

[General anesthesia without nitrogen monoxide. Its use in abdominal surgery].

In view of the problems relating to the routine use of nitrogen monoxide in general anesthesia, the authors drew up an anesthesiological protocol excluding the use of N2O and replacing its analgesic effect with higher doses of fentanyl and a higher inspired percentage of isoflurane. Twenty-three patients due to undergo abdominal surgery were included in the study. The established anesthetic protocol was evaluated by the constant measurement of PAOS/D and heart rate, as well as lacrimation and sweating.

[Subarachnoid anesthesia and peridural anesthesia: which are the causes of total failure? A clinical case].

The paper reports the case of patient undergoing cystoscopy and subsequently radical cystectomy suffering from BPCO and pulmonary emphysema who received sub-arachnoid anesthesia during the first operation and peridural anesthesia during the second, with total failure both times. The techniques were correctly performed and on both occasions it was necessary to resort to general anesthesia in order to perform the operation.

SEQUAL: an interactive computer program for sequential classification of biomedical data.

A computer program for sequential bayesian classification of patterns defined by integer and real-valued data is described. Classified patterns from a training sample are used to estimate the non-parametric (kernel) probability density functions and the a-priori class probabilities necessary to implement the bayesian classification. For each pattern and at each step in the sequential program, the 'best' feature to be measured at the next step is computed on the basis of the estimated misallocation error rate.

Computer simulation of portal venous shunting and other isolated hepatobiliary defects of the enterohepatic circulation of bile acids using a physiological pharmacokinetic model.

The effect of three isolated defects in the enterohepatic circulation of bile acids on the size and distribution of the bile acid pool, plasma bile acid levels and bile acid secretion into the intestine was simulated using a linear multicompartmental physiological pharmacokinetic model previously used to simulate these aspects of bile acid metabolism in healthy man. Stepwise increases in portal-systemic shunting (with a reciprocal decrease in hepatic blood flow) caused an exponential increase in systemic plasma concentrations of bile acids, but no other major changes in bile acid metabolism. When the effect of varying fractional hepatic extraction was simulated, it was found that the greater the fractional hepatic extraction, the greater the elevation observed for systemic plasma bile acid levels for a given degree of portal-systemic shunting.

Simulation of the metabolism and enterohepatic circulation of endogenous deoxycholic acid in humans using a physiologic pharmacokinetic model for bile acid metabolism.

The metabolism and enterohepatic circulation of deoxycholic acid (DCA), a major secondary bile acid in humans, was simulated using a linear multicompartmental physiologic pharmacokinetic model. The model was similar to that previously reported and used to simulate the metabolism of cholic acid and chenodeoxycholic acid, but differed in two respects: (a) the input of newly formed DCA molecules originated from colonic absorption rather than from de novo hepatic biosynthesis and (b) a new type of transfer coefficient was proposed to describe the movement of DCA molecules from an insoluble, bound compartment to a soluble compartment. Simulations were performed to define the effect of varying fractional colonic absorption (from 0.

Simulation of the metabolism and enterohepatic circulation of endogenous chenodeoxycholic acid in man using a physiological pharmacokinetic model.

The metabolism and enterohepatic circulation of chenodeoxycholic acid (CDC), a major primary bile acid in man, has been stimulated using a multicompartmental physiological pharmacokinetic model which was previously reported and used to simulate the metabolism of cholic acid. The model features compartments and linear transfer coefficients. Compartments, which are defined as the pools of single chemical species in well defined anatomical volumes, are aggregated into nine 'spaces' based on anatomical and physiological considerations (liver, gall-bladder, bile ducts, duodeno-jejunum, ileum, colon, portal blood, sinusoidal blood, and general circulation).

Sorbitol clearance: a parameter reflecting liver plasma flow in the rat.

According to the clearance concepts, the functional liver plasma flow may be directly measured from the plasma kinetics of any substance whose hepatic intrinsic clearance largely exceeds liver perfusion. The present study was designed to ascertain the requirements for the reliability of D-sorbitol plasma clearance in evaluating changes of liver perfusion in the male Wistar rat. The plasma disappearance curve of D-sorbitol (3 mg/100 g b.

Should blood transport kinetics be modeled in metabolic processes?

We analyze the interaction between blood transport phenomena and uptake processes when drug kinetics are studied with compartmental models. Relevant advantages in the physiological interpretation of the model parameters are obtained when blood transport is explicitly included in the model. This is done by aggregating into a single compartment all the blood spaces where no exchange with extravascular spaces takes place and separating into different blood compartments those spaces where some uptake and/or return occurs.

Advanced modeling and identification techniques for metabolic processes.

This paper will be devoted to demonstrating that a better understanding of complex metabolic processes requires a deep and reliable interpretation of much experimental data. Indeed this aim cannot be satisfied without the use of advanced modeling and identification techniques and their deep critical analysis. In fact, complete procedures should consider all the following steps: (1) definition of scopes, (2) prior information and hypotheses, (3) choice of experimental conditions, (4) derivation of possible classes of models, (5) parameter estimation, (6) errors evaluation, (7) validation and ordering of the identified models.

Qualitative and quantitative evaluation of liver diseases: functional classifications.

The problem of the best use of experimental data for qualitative and quantitative evaluation of liver disfunction is analysed. Only statistical procedures for classification are considered. Emphasis is placed on a complete description of the most important steps that must be performed (degree of clustering of the data, validity of the hypotheses underlying the statistical methods used, meaning and adequate use of the reference classification, reliability of the different statistical methods used, information content of the laboratory tests studied) since the omission of any of them may contribute to a misleading interpretation of the overall results or may prevent significant practical utilization.

Description and simulation of a physiological pharmacokinetic model for the metabolism and enterohepatic circulation of bile acids in man. Cholic acid in healthy man.

A multicompartmental pharmacokinetic model based on physiological principles, experimental data, and the standard mathematical principles of compartmental analysis has been constructed that fully describes the metabolism and enterohepatic cycling in man of cholic acid, a major bile acid. The model features compartments and linear transfer coefficients. The compartments are aggregated into nine spaces based on physiological considerations (liver, gallbladder, bile ducts, jejunum, ileum, colon, portal blood sinusoidal blood, and general circulation).