In vivo estimation of the shoulder joint center of rotation using magneto-inertial sensors: MRI-based accuracy and repeatability assessment.

BACKGROUND: The human gleno-humeral joint is normally represented as a spherical hinge and its center of rotation is used to construct humerus anatomical axes and as reduction point for the computation of the internal joint moments. The position of the gleno-humeral joint center (GHJC) can be estimated by recording ad hoc shoulder joint movement following a functional approach. In the last years, extensive research has been conducted to improve GHJC estimate as obtained from positioning systems such as stereo-photogrammetry or electromagnetic tracking. Conversely, despite the growing interest for wearable technologies in the field of human movement analysis, no studies investigated the problem of GHJC estimation using miniaturized magneto-inertial measurement units (MIMUs). The aim of this study was to evaluate both accuracy and precision of the GHJC estimation as obtained using a MIMU-based methodology and a functional approach. METHODS: Five different functional methods were implemented and comparatively assessed under different experimental conditions (two types of shoulder motions: cross and star type motion; two joint velocities: ωmax = 90°/s, 180°/s; two ranges of motion: Ɵ = 45°, 90°). Validation was conducted on five healthy subjects and true GHJC locations were obtained using magnetic resonance imaging. RESULTS: The best performing methods (NAP and SAC) showed an accuracy in the estimate of the GHJC between 20.6 and 21.9 mm and repeatability values between 9.4 and 10.4 mm. Methods performance did not show significant differences for the type of arm motion analyzed or a reduction of the arm angular velocity (180°/s and 90°/s). In addition, a reduction of the joint range of motion (90° and 45°) did not seem to influence significantly the GHJC position estimate except in a few subject-method combinations. CONCLUSIONS: MIMU-based functional methods can be used to estimate the GHJC position in vivo with errors of the same order of magnitude than those obtained using traditionally stereo-photogrammetric techniques. The methodology proposed seemed to be robust under different experimental conditions. The present paper was awarded as "SIAMOC Best Methodological Paper 2016".

Home tele-rehabilitation for rheumatic patients: impact and satisfaction of care analysis.

Introduction In this paper, we evaluated patients' perspectives on the use of a system for home tele-rehabilitation, designed for subjects with low computer literacy suffering hand impairment due to rheumatic diseases. Methods After a clinical trial assessing device effectiveness, the Psychosocial Impact of Assistive Devices Scale (PIADS), Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) and Individually Prioritised Problem Assessment (IPPA) questionnaires were administered to evaluate the system's impact on each patient's life, and the results were correlated with clinical indices. Patients were asked to continue self-administered rehabilitation with common objects. One year later, a semi-structured telephone interview gathered data on their experience. Results The system received a positive QUEST score (4.5 ± 0.3) and a modest PIADS score (0.84 ± 0.8) due to the small impact on adaptability and self-esteem. The IPPA (3.7 ± 3.4) revealed improvement in the ability to perform tasks considered important, which was significantly correlated ( r = 0.60; p < 0.02) with the clinical Health Assessment Questionnaire (HAQ) index improvement. The interviews revealed a positive engagement effect, enhanced by the need to develop skills to be able to use the device (technological challenge) and by the perception of more attention by the medical staff. This may explain the significant dropout rate (80%) from the post-trial rehabilitation of the patients who used the device. Discussion The system was largely accepted by the patients. The results suggest that the need for information on their rehabilitation progress and the technological challenge deserves further study to make patients more autonomous in cases of continuous rehabilitation.

Estimation of the center of rotation using wearable magneto-inertial sensors.

Determining the center of rotation (CoR) of joints is fundamental to the field of human movement analysis. CoR can be determined using a magneto-inertial measurement unit (MIMU) using a functional approach requiring a calibration exercise. We systematically investigated the influence of different experimental conditions that can affect precision and accuracy while estimating the CoR, such as (a) angular joint velocity, (b) distance between the MIMU and the CoR, (c) type of the joint motion implemented, (d) amplitude of the angular range of motion, (e) model of the MIMU used for data recording, (f) amplitude of additive noise on inertial signals, and (g) amplitude of the errors in the MIMU orientation. The evaluation process was articulated at three levels: assessment through experiments using a mechanical device, mathematical simulation, and an analytical propagation model of the noise. The results reveal that joint angular velocity significantly impacted CoR identification, and hence, slow joint movement should be avoided. An accurate estimation of the MIMU orientation is also fundamental for accurately subtracting the contribution owing to gravity to obtain the coordinate acceleration. The unit should be preferably attached close to the CoR, but both type and range of motion do not appear to be critical. When the proposed methodology is correctly implemented, error in the CoR estimates is expected to be <3mm (best estimates=2±0.5mm). The findings of the present study foster the need to further investigate this methodology for application in human subjects.

Peripheral neural activity recording and stimulation system.

This paper presents a portable, embedded, microcontroller-based system for bidirectional communication (recording and stimulation) between an electrode, implanted in the peripheral nervous system, and a host computer. The device is able to record and digitize spontaneous and/or evoked neural activities and store them in data files on a PC. In addition, the system has the capability of providing electrical stimulation of peripheral nerves, injecting biphasic current pulses with programmable duration, intensity, and frequency. The recording system provides a highly selective band-pass filter from 800 Hz to 3 kHz, with a gain of 56 dB. The amplification range can be further extended to 96 dB with a variable gain amplifier. The proposed acquisition/stimulation circuitry has been successfully tested through in vivo measurements, implanting a tf-LIFE electrode in the sciatic nerve of a rat. Once implanted, the device showed an input referred noise of 0.83 µVrms, was capable of recording signals below 10 µ V, and generated muscle responses to injected stimuli. The results demonstrate the capability of processing and transmitting neural signals with very low distortion and with a power consumption lower than 1 W. A graphic, user-friendly interface has been developed to facilitate the configuration of the entire system, providing the possibility to activate stimulation and monitor recordings in real time.

A tele-home care system exploiting the DVB-T technology and MHP.

OBJECTIVES: The aim of this research work is the development of a low-cost system for telemedicine based on the DVB-T technology. The diffusion of DVB-T standard and the low cost of DVB-T set-top boxes bring the vision of a capillary distribution of tele-home care monitoring systems with easy-to-use patient's interface. METHODS: Exploiting the potentiality of the DVB-T set-top box, we transformed it into an "on-demand tele-home care interface". The Xlet we developed is able to govern the functionality of an external microcontroller-based unit for the acquisition of the bio-signals of interest. The uplink connection is used to send the exam results to a remote care center. RESULTS: The Xlet providing the patient interface on the set-top box is uploaded by a DVB-T broadcaster without any intervention in the patient's home. A prototypal low-cost base station for the acquisition of the patient's signals (1-lead ECG) has been developed. It is able to be connected to the set-top box via an infrared link. A smart-card-based system is in charge for the customization of the Xlet for every patient. CONCLUSIONS: The proposed system, based on a currently widespread infrastructure, is able to allow the patients monitoring from home without any installation procedure. Even untrained (or elderly) people can easily use such system due to their practice with the basic DVB-T home-entertainment equipments.

Pulsatility index of temporal and renal arteries as an early finding of arteriopathy in diabetic patients.

The objective of this study was to investigate the relationship between alterations in the elasticity of the temporal and the renal arteries and the grade of arteriopathy, using the pulsatility index in type II diabetic patients and healthy volunteers. All individuals were divided into groups. Group A consisted of 15 patients without risk factors (hyperlipidemia, hypertension, obesity, and smoking) and had well-controlled diabetes mellitus as demonstrated by normal values of HbA1c. Group B had 20 patients with two risk factors (hyperlipidemia and hypertension) and normal HbA1c. Group C (25 patients) had four risk factors and high values of HbA1c, and group D consisted of 20 healthy individuals. All patients were examined by use of color Doppler ultrasonography. Pulsatility index values were measured in the temporal and renal arteries. Pulsatility indices of temporal arteries were higher in group C than in groups A and B, whereas for the renal arteries, no significant difference was detected between the four groups. In our study there seems to be strong correlation between increased values of pulsatility index, mainly in the temporal arteries, and grade of arteriopathy in type II diabetic patients.

Heterotopic gastric mucosa in the upper esophagus: report of a case with a fistula.

We report the case of a 36-year-old man with a patch of heterotopic gastric mucosa in the upper esophagus complicated by an esophageal fistula.

Analog VLSI circuits as physical structures for perception in early visual tasks.

A variety of computational tasks in early vision can be formulated through lattice networks. The cooperative action of these networks depends on the topology of interconnections, both feedforward and recurrent ones. This paper shows that it is possible to consider a distinct general architectural solution for all recurrent computations of any given order. The Gabor-like impulse response of a second-order network is analyzed in detail, pointing out how a near-optimal filtering behavior in space and frequency domains can be achieved through excitatory/inhibitory interactions without impairing the stability of the system. These architectures can be mapped, very efficiently at transistor level, on very large scale integration (VLSI) structures operating as analog perceptual engines. The problem of hardware implementation of early vision tasks can, indeed, be tackled by combining these perceptual agents through suitable weighted sums. A 17-node analog current-mode VLSI circuit has been implemented on a CMOS 2 microm, NWELL, single-poly, and double-metal technology, to demonstrate the feasibility of the approach. Applications of the perceptual engine to various machine vision algorithms are proposed.

Functional periodic intracortical couplings induced by structured lateral inhibition in a linear cortical network.

The spatial organization of cortical axon and dendritic fields could be an interesting structural paradigm to obtain a functional specificity without postulating highly specific feedforward connections. In this article, we investigate the functional implications of recurrent intracortical inhibition when it occurs through clustered medium-range interconnection schemes (Wörgötter & Koch, 1991; Somogyi, 1989; Kritzer, Cowey, & Somogyi, 1992). Moreover, the interaction between the inhibitory schemes and visual orientation maps is explored. Assuming linearity, we show that clustered inhibitory mechanisms can trigger a propagation process that allows the development of extra (i.e., induced) interactions among the cortical sites involved in the recurrent loops. In addition, we point out how these interactions functionally modify the response of cortical simple cells and yield to highly structured Gabor-like receptive fields. This study should be considered not as a realistic biological model of the primary visual cortex but as an attempt to explain possible computational principles related to intracortical connectivity and to the underlying single-cell properties.

Criptococosis asociada al SIDA en el Hospital Posadas: estudio de 30 casos / Cryptococcosis associated with AIDS in the Posadas Hospital: study of 30 cases

Se estudiaron aspectos epidemiológicos, inmunológicos y diagnósticos de 30 casos de criptococosis asociada al SIDA [22 (73,33 por ciento) varones y 8 mujeres (26,67 por ciento)], diagnosticados en el Hospital "Alejandro Posadas" entre 1991 y 1995. La mediana de la edad de la población estudiada fue de 28 años. La mediana del tiempo transcurrido entre el momento del diagnóstico de la infección por el VIH y el de la criptococosis fue de 1 (0-7) año, (<1-7) años en los adictos a drogas por vía endovenosa y de 4 (4-6) años en los homo/bisexuales. La adicción endovenosa a drogas fue el factor de riesgo predominante para la infección por el HIV y se observó en 16 pacientes (53,33 por ciento). El diagnóstico de criptococosis se estableció en 17 (56,67 por ciento) enfermos por microscopia con tinta china de LCR, en 10 (33,33 por ciento) mediante hemocultivos (lisis-centrifugación) y en los 3 (10 por ciento) restantes por otros métodos. Todas las cepas aisladas de los casos estudiados se identificaron como Cryptococcos neoformans variedad neoformans, mediante la asimilación de la D-prolina y el uso de medio de Salink & Hurd. En el momento del diagnóstico, el recuento de linfocitos T CD4+ fue < 50/µL en 6 pacientes (40 por ciento). 51 a 100/µL en 3 (20 por ciento), 101 a 200/µL en 5 (33,33 por ciento) y > 200/µL en 1 (6,67 por ciento) paciente. El 72,22 por ciento de los pacientes había nacido en la Ciudad de Buenos Aires (Bs. As.) y el Gran Bs. As. y en el momento del diagnóstico el 36,66 por ciento de ellos residía en localidades del Gran Bs. As

Criptococosis asociada al SIDA en el Hospital Posadas: estudio de 30 casos / Cryptococcosis associated with AIDS in the Posadas Hospital: study of 30 cases

Se estudiaron aspectos epidemiológicos, inmunológicos y diagnósticos de 30 casos de criptococosis asociada al SIDA [22 (73,33 por ciento) varones y 8 mujeres (26,67 por ciento)], diagnosticados en el Hospital "Alejandro Posadas" entre 1991 y 1995. La mediana de la edad de la población estudiada fue de 28 años. La mediana del tiempo transcurrido entre el momento del diagnóstico de la infección por el VIH y el de la criptococosis fue de 1 (0-7) año, (<1-7) años en los adictos a drogas por vía endovenosa y de 4 (4-6) años en los homo/bisexuales. La adicción endovenosa a drogas fue el factor de riesgo predominante para la infección por el HIV y se observó en 16 pacientes (53,33 por ciento). El diagnóstico de criptococosis se estableció en 17 (56,67 por ciento) enfermos por microscopia con tinta china de LCR, en 10 (33,33 por ciento) mediante hemocultivos (lisis-centrifugación) y en los 3 (10 por ciento) restantes por otros métodos. Todas las cepas aisladas de los casos estudiados se identificaron como Cryptococcos neoformans variedad neoformans, mediante la asimilación de la D-prolina y el uso de medio de Salink & Hurd. En el momento del diagnóstico, el recuento de linfocitos T CD4+ fue < 50/AL en 6 pacientes (40 por ciento). 51 a 100/AL en 3 (20 por ciento), 101 a 200/AL en 5 (33,33 por ciento) y > 200/AL en 1 (6,67 por ciento) paciente. El 72,22 por ciento de los pacientes había nacido en la Ciudad de Buenos Aires (Bs. As.) y el Gran Bs. As. y en el momento del diagnóstico el 36,66 por ciento de ellos residía en localidades del Gran Bs. As (AU)

[Acute and chronic diarrhea in AIDS: study of 435 (HIV+) patients, in Buenos Aires]. / Diarrea aguda y crónica en SIDA: estudio de 435 pacientes HIV(+), en Buenos Aires.

OBJECTIVE: Assessment of the rate of Diarrhoea in an infected HIV population of our medium. Assessment of its etiology, risk factors and response to treatment in both presentation of disease (Acute and chronic). DESIGN: This is a retrospective analysis of HIV and/or AIDS patients and diarrhea. The analytic points were: the clinical pattern of diarrhea (acute or chronic), risk factors, age, sex, etiology, stage of the disease, and response rate to treatment. PLACE: Hospital Prof. A. Posadas, that is situated in the greater Buenos Aires, and that functions as a referral centre for AIDS patients. PATIENTS AND METHODS: 435 case records that were followed up through June 1987/ March 1994 were reviewed; 109 of the total number suffered from diarrhea. RESULTS: The rate of diarrhoea in the studied population was 25% (109/435). This represented the first symptom of HIV infection in 18.3% of the patients (20/109), 49% had acute diarrhea and 51% had chronic diarrhea. An etiologic agent was established in 52.3% of the chronic diarrhoeas and in the 17.7% of the acute ones, with a 35.4% of a global isolation when basic stool test were made. Sixty three percent of the patients with chronic diarrhoea were in stage IV of HIV infection. The 78.3% of the acute diarrhoeas and 46% of the chronic ones were responsive to specific or symptomatic treatment. CONCLUSIONS: HIV antibodies determinations should be included in the study protocol of diarrhea, especially in young patients. Chronic diarrhea could be related to final stages of the disease, with lower response to treatment. Endoscopy studies should be useful when the stool tests are negative, specially in the Cytomegalovirus (CMV) and Mycobacterium complex avium intracellulare (MAI) search.

Traumatismos de la traquea y grandes bronquios. / Tracheal and major bronchi injuries

El diagnostico de herida de traquea y grandes bronquios puede sospecharse ante la presencia de enfisema subcutaneo y mediastinico, en ocasiones asociado a neumotorax; la presencia de hemoptisis acrecentara la posibilidad de lesiones a esos niveles. Los signos arriba senalados son los mas destacables, pero el diagnostico definitivo se hara mediante la observacion directa a traves de la broncoscopia. La terapeutica quirurgica especifica se extiende desde la simple sutura hasta la reseccion segmentaria o lobar. Distintos metodos de reparacion de la traquea y grandes bronquios (plasticas), son utilizados y, en caso de seccion completa, sin compromiso vascular, puede intentarse la anastomosis en las primeras horas de la injuria.La terapeutica quirurgica complementaria incluye la traqueostomia

Traumatismos costales con respiracion paradojica. / Flail chest injuries with paradoxical respiration

Se describen las etapas fisiopatologicas de la insuficiencia respiratoria, consecutivas a la presencia de un "volet" con respiracion paradojica, enfatizando la gravedad del cuadro que exige un rapido diagnostico y correcto tratamiento. Para esto ultimo, recurrimos a metodos quirurgicos de distinta magnitud con resultados satisfactorios, en una serie de 70 casos tratados en nuestro medio hospitalario.Debido a la no existencia de aparatologia especifica (respiradores), en nuestra institucion, el total de pacientes tratados, lo fueron con los metodos previamente descriptos. Estos casos no requerian, segun nuestra indicacion, asistencia respiratoria mecanica. Fallecieron 19 traumatizados como consecuencia de lesiones asociadas intra y extratoracicas

Traumatismos de la traquea y grandes bronquios. / Tracheal and major bronchi injuries

El diagnostico de herida de traquea y grandes bronquios puede sospecharse ante la presencia de enfisema subcutaneo y mediastinico, en ocasiones asociado a neumotorax; la presencia de hemoptisis acrecentara la posibilidad de lesiones a esos niveles. Los signos arriba senalados son los mas destacables, pero el diagnostico definitivo se hara mediante la observacion directa a traves de la broncoscopia. La terapeutica quirurgica especifica se extiende desde la simple sutura hasta la reseccion segmentaria o lobar. Distintos metodos de reparacion de la traquea y grandes bronquios (plasticas), son utilizados y, en caso de seccion completa, sin compromiso vascular, puede intentarse la anastomosis en las primeras horas de la injuria.La terapeutica quirurgica complementaria incluye la traqueostomia

Traumatismos costales con respiracion paradojica. / Flail chest injuries with paradoxical respiration

Se describen las etapas fisiopatologicas de la insuficiencia respiratoria, consecutivas a la presencia de un "volet" con respiracion paradojica, enfatizando la gravedad del cuadro que exige un rapido diagnostico y correcto tratamiento. Para esto ultimo, recurrimos a metodos quirurgicos de distinta magnitud con resultados satisfactorios, en una serie de 70 casos tratados en nuestro medio hospitalario.Debido a la no existencia de aparatologia especifica (respiradores), en nuestra institucion, el total de pacientes tratados, lo fueron con los metodos previamente descriptos. Estos casos no requerian, segun nuestra indicacion, asistencia respiratoria mecanica. Fallecieron 19 traumatizados como consecuencia de lesiones asociadas intra y extratoracicas