CMOS neurostimulation ASIC with 100 channels, scaleable output, and bidirectional radio-frequency telemetry.

100-channel neurostimulation circuit comprising a complementary metal oxide semiconductor (CMOS), application-specific integrated circuit (ASIC) has been designed, constructed and tested. The ASIC forms a significant milestone and an integral component of a 100-electrode neurostimulation system being developed by the authors. The system comprises an externally worn transmitter and a body implantable stimulator.

Sensorless flow and head estimation in the VentrAssist rotary blood pump.

Flow rate and pressure difference (or head) are key variables needed in the control of implantable rotary blood pumps. However, use of flow and/or pressure probes can decrease reliability and increase system power consumption and expense. For a given fluid viscosity, the flow state is determined by any 2 of the 4 pump variables: Flow, pressure difference, speed, and motor input power can be used.

Associations of sociodemographic, psychosocial, and behavioral factors with sexual risk and sexually transmitted diseases in teen clinic patients.

Purpose: To examine the influence of sociodemographic characteristics, sexually transmitted disease (STD)/human immunodeficiency virus knowledge, and psychosocial and behavioral risk factors on sexual risk and STDs in adolescents using constructs from the Information, Motivation, and Behavioral Skills model (IMB).

Methods: A convenience sample of 303 sexually experienced, racially diverse adolescents (mean age 16.7 years, 57.

Skeletal evidence of probable treponemal infection in free-ranging African apes.

The prevalence and patterning of inflammatory lesions of the skeleton were investigated in samples of chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) curated at the Powell-Cotton Museum, Birchington, UK. One hundred and two chimpanzees (42 adults and 60 subadults) and 126 gorillas (50 adults and 76 subadults) comprise the samples. Twenty per cent of chimpanzees and 14% of gorillas were affected with a disseminated inflammatory skeletal condition caused by infection.

The potential impact of home telecare on clinical practice.

Home telecare, in which the health status of patients at home is monitored remotely, has the potential to improve care and reduce costs. Its widespread implementation would require fundamental changes in the healthcare system.

Research and clinical assessment of eating and exercise behaviour.

The Eating and Exercise Examination (EEE-C) is an efficient, self-report, computer-generated and computer-reported examination of eating and exercise behaviour, attitudes and feelings. It is clinically useful for assessment of eating and exercise disorders, as a therapeutic tool to provide feedback to patients and as an instrument to provide standardized data for cost effective and relapse prevention studies.

Patterns of dental enamel defects at ancient Mendes, Egypt.

The dental remains of 88 individuals from Old Kingdom, First Intermediate, and Greco-Roman periods at the ancient Egyptian site of Mendes (Tell er-Rub(c)a) were examined for dental enamel hypoplasia, and the results reported here provide some of the first comparative data on enamel defects in ancient Egypt. Overall, 48% of the individuals in the sample have one or more teeth with hypoplasia, with 17% of permanent teeth and 8% of deciduous teeth affected. The permanent teeth account for 87% of the total number of affected teeth, a prevalence over deciduous teeth that is significant at alpha = 0.

Information technology in primary health care.

Appropriate application of information technology in primary health care will extend traditional diagnosis and patient management beyond the doctor's clinic into the everyday living environment. We describe a model of information management in primary health care, and place special emphasis on the emerging areas of clinical decision support, computerised clinical measurements, patient education and network connectivity. Briefly discussed is the design of innovative home monitoring techniques and a telemedicine based communications infrastructure that should improve access to high quality primary health care for all citizens, irrespective of their distance from major urban centres.

A web-based approach for electrocardiogram monitoring in the home.

A Web-based electrocardiogram (ECG) monitoring service in which a longitudinal clinical record is used for management of patients, is described. The Web application is used to collect clinical data from the patient's home. A database on the server acts as a central repository where this clinical information is stored.

The bionic eye (electronic visual prosthesis): a review.

The concept of a visual prosthesis for the blind or partially sighted is not a new one. Indeed, for more than three decades this technology based treatment for blindness has appeared imminent. Despite the concerted efforts of numerous physicians, scientists and engineers, the successful application of a useful visual prosthesis remains elusive.

Review of ionic models of vagal-cardiac pacemaker control.

Mathematical models of ion currents in pacemaker cells of the heart and their associated modulation by vagal stimulation have provided numerous insights into the ionic mechanisms underlying parasympathetic control of heart rate. In this article, ionic models described in the literature are reviewed and compared, with a view to examining their effectiveness in reproducing known chronotropic responses to vagal stimulation.

Monte Carlo simulation of tuning capacitor selection in a cochlear implant.

The principles of Monte Carlo simulation are applied to critical manufacturing process in the construction of cochlear implants. In this application, the tuning of the implant's radio frequency (RF) communication system is dependent upon a "select on test" tuning capacitance. The aim is to accurately predict the usage of capacitors of a given size in future production of cochlear implants using Monte-Carlo simulation.

Simulations of postvagal tachycardia at the single cell pacemaker level: a new hypothesis.

Simulations performed on a single cell model of rabbit sinoatrial node activity after prolonged vagal stimulation have been able to reproduce the known characteristics of cycle length recovery, including the presence of rapid and slow recovery phases and the transient undershoot phenomenon known as postvagal tachycardia (PVT). In the model, the PVT component has been hypothesized to result from the recovery of background levels of the muscarinic K+ current iK,ACh from desensitization due to prolonged exposure to acetylcholine (ACh) neurotransmitter. Other components of the recovery were found to be due to the inactivation of iK,ACh after the hydrolysis of ACh (rapid phase) and the recovery of the hyperpolarizing-activated current i(f) from its ACh-induced inhibition (slow phase).

Concordance of cranial and dental morphological traits and evidence for endogamy in ancient Egypt.

A biological affinities study based on frequencies of cranial nonmetric traits in skeletal samples from three cemeteries at predynastic Naqada, Egypt, confirms the results of a recent nonmetric dental morphological analysis. Both cranial and dental traits analyses indicate that the individuals buried in a cemetery characterized archaeologically as high status are significantly different from individuals buried in two other, apparently nonelite cemeteries and that the nonelite samples are not significantly different from each other. A comparison with neighbouring Nile Valley skeletal samples suggests that the high status cemetery represents an endogamous ruling or elite segment of the local population at Naqada, which is more closely related to populations in northern Nubia than to neighbouring populations in southern Egypt.

Vagal control of sinoatrial rhythm: a mathematical model.

The ionic mechanisms underlying vagal control of the cardiac pacemaker were investigated using a new single cell mathematical model of sinoatrial node electrical activity. The model was formulated from a wide range of electrophysiological data available in the literature, with particular reference to whole cell recordings from enzymatically isolated sinoatrial node cells. Development of the model was prompted by the lack of an existing physiologically accurate formulation of sinoatrial node activity that could reproduce the known complex chronotropic response of the pacemaker to brief-burst vagal stimulation, as observed in whole animal and isolated sinus node preparations.

Ion currents underlying sinoatrial node pacemaker activity: a new single cell mathematical model.

The ionic currents underlying autorhythmicity of the mammalian sinoatrial node and their wider contribution to each phase of the action potential have been investigated in this study using a new single cell mathematical model. The new model provides a review and update of existing formulations of sinoatrial node membrane currents, derived from a wide range of electrophysiological data available in the literature. Simulations of spontaneous activity suggest that the dominant mechanism underlying pacemaker depolarisation is the inward background Na+ current, ib,Na.

Class III Antiarrhythmic Effects of Dofetilide in Rabbit Atrial Myocardium.

BACKGROUND: Dofetilide is a new class III antiarrhythmic agent with demonstrated efficacy in ventricular and atrial tachyarrhythmias. We investigated its class III actions and their modulation by stimulation rate in rabbit atrial myocardium. METHODS AND RESULTS: Standard microelectrode techniques were used to record action potentials from rabbit atrial tissue at varying stimulation rates.

Remote monitoring of health status of the elderly at home. A multidisciplinary project on aging at the University of New South Wales.

This paper discusses the design and implementation of a multidisciplinary research project and associated field trials to test the hypothesis that functional health status amongst the elderly can be accurately determined remotely by continuously monitoring relatively simple parameters that measure the interaction between participants and their environment. In this study we propose that changes in such simple measures as mobility, sleep patterns, and utilisation of cooking, washing and toilet facilities, can identify changes in functional health status. One of the primary end goals of the project will be to automatically prompt appropriate, timely and cost-effective intervention of medical and community based services to help reduce morbidity and maintain an independent high quality of life for the elderly.

Implementation of a clinical workstation for general practice.

It is now well recognized that achieving international best practice in the primary health sector will require the development of methods based on a fundamental integration of communications and information technologies with clinical practice. This will have far reaching effects, both on the pattern of medical practice and domiciliary care and on patient outcomes. In the past, information and communications technology has been presented as a tool for management, rather than as a tool for supporting, improving, and making more efficient the professional practice of medicine and the delivery of health care to the patient and the community.

Remote home monitoring of health status of the elderly.

The hypothesis that functional health status amongst the elderly can be accurately determined remotely by continuously monitoring relatively simple parameters that measure the interaction between the participant and his or her environment was examined. Changes in such simple measures as mobility, sleep patterns, utilization of cooking, washing, and toilet facilities can identify changes in functional health status and prompt appropriate, timely, and cost-effective intervention of medical and community-based services to help reduce morbidity and maintain an independent, high quality of life. We discuss the design and implementation of a multidisciplinary research project and an associated field trial to unobtrusively monitor and correlate interaction with the home environment and functional health status.

Exogenous arginine vasopressin does not enhance carotid baroreflex control in the conscious dog.

Arginine vasopressin (AVP) has profound effects on the cardiovascular system, yet has minimal pressor activity at physiological levels in intact subjects. We designed an investigation to delineate the effects of AVP on open-loop carotid baroreflex control of mean arterial pressure (MAP), total peripheral resistance (TPR), and cardiac output (CO) in conscious, chronically instrumented dogs. During graded infusions of AVP (0.

Biological differentiation at predynastic Naqada, Egypt: an analysis of dental morphological traits.

Cemetery T at Naqada has been postulated as being the interment site of a predynastic royal or ruling elite due to its small, localized area and the richness of its burial goods. In order to examine possible biological differentiation between the individuals buried in Cemetery T and those buried in other, possibly lower status cemeteries at Naqada, nonmetric dental morphological data were analyzed using the Mean Measure of Divergence statistic. Results indicate that Cemetery T shows some biological distinction from both Cemetery B and the Great Cemetery.

Spinal arthritis and physical stress at Bronze Age Harappa.

This study examines joint changes in the vertebral skeleton in human remains excavated in 1987 and 1988 at Bronze Age Harappa, an urban center of the Indus Valley civilization. The sample consists of 23 complete skeletons from primary burial context, the partial remains of more than 69 other individuals, and hundreds of skeletal elements from secondary context, totalling 3,084 vertebral joint margins and articular surfaces. Marginal bone proliferation, pitting of articular surfaces, eburnation, and ankylosis were scored macroscopically for vertebral body margins and surfaces and posterior apophyseal facet joints.

Modification of DiFrancesco-Noble equations to simulate the effects of vagal stimulation on in vivo mammalian sinoatrial node electrical activity.

We present a new mathematical model for vagal control of rabbit sinoatrial (SA) node electrical activity based on the DiFrancesco-Noble equations. The original equations were found to be unstable, resulting in progressive cycle by cycle depletion or accumulation of ions in intra- and extracellular compartments. This problem was overcome by modifying the maximum Na-K pump current and the time constant for uptake of intracellular calcium.