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A commercial single degree of freedom artificial hand has been fitted with touch, slip and position sensors, which permit low-level control tasks to be performed by a microprocessor; little conscious effort is required by the wearer. Hardware and software for the microprocessor system are described.
An integrated animal research facility is planned by NASA for Space Station Freedom which will permit long-term, man-tended experiments on the effects of space conditions on vertebrates. The key element in this facility is a standard type animal habitat which supports and maintains the animals under full bioisolation during transport and during the experiment. A holding unit accommodates the habitats with animals to be maintained at zero gravity; and a centrifuge, those to be maintained at artificial gravity for control purposes or for gravity threshold studies. A glovebox permits handling of the animals for experimental purposes and for transfer to a clean habitat. These facilities are described, and the aspects of environmental control, monitoring, and bioisolation are discussed.
PURPOSE: To evaluate short-term clinical and chemical disease progression following computed tomography (CT)-based transperineal I-125 prostate implantation. METHODS AND MATERIALS: Sixty-two patients with clinical Stage T1 or T2 prostatic carcinoma had outpatient, CT-based transperineal I-125 prostate implantation and have been followed for 6-55 months (median: 19 months). Fifty-six patients had an elevated prostate specific antigen (PSA) before implantation (> 4.0 ng/mL). Twenty patients had well-differentiated tumors, 39 were moderately differentiated, 2 were poorly differentiated, and 1 was indeterminate. A total of 32-73 mCi I-125 was implanted (median: 47 mCi). The prescribed minimum prostatic dose was 140-160 Gy, and the actual matched peripheral dose ranged from 109-258 Gy (median: 160 Gy). Lymph node dissection or postimplantation prostatic biopsies were not routinely performed. RESULTS: Of 54 patients with an elevated PSA prior to implantation and no prior hormonal treatment, 96% returned to normal within 24 months of treatment. In 85% of patients, the PSA fell below 2.0 ng/mL and in 74% of patients, the PSA value fell to below 1.0 ng/mL. Seven patients had disease progression, one of whom has an isolated, rising PSA. The actuarial rate of chemical (rising PSA) or clinical failure at 3 years following implantation was 17%. Of 38 patients who were sexually potent prior to implantation, 81% remained potent at 3 years. Five patients developed radiation-induced rectal ulcerations, 11-22 months following implantation. Three patients required a transurethral resection of the prostate for postimplant urinary symptoms. CONCLUSIONS: The short-term clinical and chemical freedom-from-progression rates following I-125 implantation are comparable to that achieved with prostatectomy, with high preservation of sexual potency and moderate morbidity.
The phenomenon that coronary arteries which course entirely intramyocardially remain immune to atherosclerosis was investigated in 250 patients undergoing coronary bypass surgery. In 26 the circumflex artery gave off major branches whose distal portions ran entirely intramyocardially, which required coronary bypass grafting because of proximal disease. Of these, 24 had no atherosclerosis in the intramyocardial segment, one had a calcified plaque, and one had a recanalized thrombus. The cause of this phenomenon was studied further in 14 canine hearts by measuring intramyocardial pressure. The intramyocardial pressure in the subepicardial region was as high as 63% of the left ventricular cavity pressure and in the subendocardial region it was even greater than the left ventricular cavity pressure, which indicates that the pressure gradient across the artery wall is significantly reduced, and sometimes even eliminated. It is therefore concluded that the freedom from atherosclerosis of the intramyocardial coronary arteries is due to the lack of mural stress, i.e. the lower or absent transmural pressure gradient.
OBJECTIVE: AutoNRT is an automated system that measures electrically evoked compound action potential (ECAP) thresholds from the auditory nerve with the Nucleus Freedom cochlear implant. ECAP thresholds along the electrode array are useful in objectively fitting cochlear implant systems for individual use. This paper provides the first detailed description of the AutoNRT algorithm and its expert systems, and reports the clinical success of AutoNRT to date. METHODS: AutoNRT determines thresholds by visual detection, using two decision tree expert systems that automatically recognise ECAPs. The expert systems are guided by a dataset of 5393 neural response measurements. The algorithm approaches threshold from lower stimulus levels, ensuring recipient safety during postoperative measurements. Intraoperative measurements use the same algorithm but proceed faster by beginning at stimulus levels much closer to threshold. When searching for ECAPs, AutoNRT uses a highly specific expert system (specificity of 99% during training, 96% during testing; sensitivity of 91% during training, 89% during testing). Once ECAPs are established, AutoNRT uses an unbiased expert system to determine an accurate threshold. Throughout the execution of the algorithm, recording parameters (such as implant amplifier gain) are automatically optimised when needed. RESULTS: In a study that included 29 intraoperative and 29 postoperative subjects (a total of 418 electrodes), AutoNRT determined a threshold in 93% of cases where a human expert also determined a threshold. When compared to the median threshold of multiple human observers on 77 randomly selected electrodes, AutoNRT performed as accurately as the 'average' clinician. CONCLUSIONS: AutoNRT has demonstrated a high success rate and a level of performance that is comparable with human experts. It has been used in many clinics worldwide throughout the clinical trial and commercial launch of Nucleus Custom Sound Suite, significantly streamlining the clinical procedures associated with cochlear implant use.
BACKGROUND: This study was designed to evaluate the outcome of Contegra xenograft valved conduit (Contegra, Medtronic Inc, Minneapolis, MN). METHODS: From April 1999 to December 2003, 67 patients with a mean age of 16.1 +/-15.0 years (2 months to 53 years) and a mean weight of 39.7 +/- 27.1 kg (4 to 95 kg) were discharged after implantation of a Contegra conduit. The diagnosis contained the following: pulmonary valve replacement during Ross operation (n = 27), pulmonary valve regurgitation (n = 9), tetralogy of Fallot (n = 7), pulmonary atresia with ventricular septal defect (n = 7), double outlet right ventricle (n = 7), truncus arteriosus (n = 5), Taussig-Bing (n = 2), obstructed conduit (n = 2), and double discordance (n = 1). Conduit size was 14 mm in 2, 16 mm in 7, 18 mm in 12, 20 mm in 13, and 22 mm in 33 patients. Mean cardiopulmonary bypass was 155 +/- 48 min (65 to 337 min) and mean aortic cross clamping was 69 +/- 38 min (0 to 146 min). All patients underwent echocardiography, 23 of 67 (34%) patients had cardiac catheterization, and 23 of 67 (34%) patients had electrocardiograph-gated multislice computer tomography. RESULTS: In a mean follow-up of 26.4 months (1 to 56 months) there was one late death (1 of 67 patients; 1.5% mortality) unrelated to the conduit. Five patients underwent reoperation; four were nonconduit-related and one was to replace a twisted conduit. Five patients underwent interventional cardiology; three were nonconduit-related and two were to stent a twisted or stenotic conduit. Echocardiography showed absent valve regurgitation in 30 of 67 (45%) patients, trivial in 21 of 67 (31%) patients, mild in 16 of 67 (24%) patients. The transconduit pressure gradient remained stable during follow-up, with peak pressure gradient 17 +/- 11 mm Hg and mean gradient 8 +/- 6 mm Hg. Internal diameters corresponded to 110% +/- 20% of the implanted diameter at level of proximal anastomosis, 112% +/- 18% at valve level, and 110% +/- 14% at distal anastomosis. Calcifications were not found, with the exception of a minimal (2.3 mm) parietal calcification. CONCLUSIONS: The Contegra valved conduit provided excellent morphology and hemodynamics, and freedom from calcification in a medium-term follow-up.
Is it possible to produce the same cognitive function with different brain organizations? This question is approached for working memory, a cognitive entity that is equally organized in birds and mammals. The critical forebrain structure for working memory is the nidopallium caudolaterale (NCL) in birds and the prefrontal cortex (PFC) in mammals. Although both structures share a large number of neural architectural features, they are probably not homologous but represent a remarkable case of convergent evolution. In reviewing the neuronal mechanisms for working memory in birds and mammals it becomes apparent that the similarities of NCL and PFC extend from the neuronal activation patterns during memory tasks down to the biophysical mechanisms of synaptic currents. Both in mammals and birds, dopamine acts via D1-receptors to tune preactivated neurons into sustained high-frequency patterns with which goal states can be held over time until an appropriate response can be generated. The degrees of freedom to create different neural architectures to solve the problem of 'stimulus maintenance' seem to be very small.
BACKGROUND: Burns comprise 5% of casualties evacuated from Operations Iraqi and Enduring Freedom (OIF and OEF). Many OIF/OEF burns result from the enemy's detonation of explosives. We reviewed these to evaluate mission impact and provide recommendations for improved combat burn protection. Data were compared to those from the Vietnam War. METHODS: All OIF/OEF patients with significant burns are treated at the U.S. Army Institute of Surgical Research (ISR). A review from April 2003 to April 2005 was undertaken. Records were obtained and demographics, burn severity and pattern, and early outcomes recorded. RESULTS: Two hundred and seventy-four OIF/OEF burn patients were treated, 142 (52%) sustained burns in explosions from hostile action. Age was 26+/-7 years (mean+/-S.D.). Mortality was 4%. The annual rate of combat explosion as a cause for burns increased from 18% to 69%, total body surface area burned increased from 15+/-12 to 21+/-23%, injury severity score rose from 8+/-11 to 17+/-18, and frequency of inhalation injury rose from 5% to 26%. Improvised explosive devices caused 55% of casualties, car bombs 16%, rocket-propelled grenades 15% and 14% other. The hands (80% of patients) and the face (77%) were the most frequently burned body areas. Burns were isolated to the hands in 6% of patients and to the face and hands in 15%. An average of 52+/-30% of the surface area of the hands and 45+/-26% of the face was burned. Mean length of stay was 24+/-25 days (median 14). Though 77% of patients were discharged without global disability, only 36% returned to full military duty. A similar pattern of injury and disposition was seen at the Army burn center in Vietnam (1966-1968), but mortality was higher (7.9%). CONCLUSION: Burns resulting from combat explosions increased in frequency, size and injury severity. Burns were concentrated on areas not protected by clothing or equipment. These injuries created long hospital stays and frequently prevented soldiers from returning to duty. While wound distribution has not changed, combat burn care has improved, and continued emphasis on military protective equipment for the hands and face is warranted.
BACKGROUND: In end-stage cardiomyopathy where concomitant chronic renal failure is a contraindication for cardiac transplantation (HTx), simultaneous heart and kidney transplantation (HKTx) may be the only feasible therapeutic option. Due to the increased donor shortage, the clinical outcome of combined HKTx patients on tacrolimus-based immunosuppression was assessed and compared with a group of HTx patients. METHODS: Three hundred forty-nine HTxs, including 13 (4%) combined HKTxs, were performed since 1995. Two hundred twenty-one HTx and all HKTx recipients received tacrolimus-based immunosuppression. Acute rejection episodes (AREs), infections, renal function and clinical outcome were evaluated. Pre-operative renal diagnoses for HKTx patients included cystic nephropathy (n = 4), glomerulonephritis (n = 4), cytostatica-induced nephropathy (n = 1), chronic rejection after renal transplant (n = 1), reflux nephropathy (n = 2) and chronic calcineurin-inhibitor -induced nephropathy after HTx (n = 1). Twelve patients (92%) were on hemodialysis pre-operatively, 1 underwent implantation of a left ventricular assist device (LVAD) before HKTx. RESULTS: After 4.7 +/- 2 years, 92% of HKTx compared with 85% of HTx patients had survived (p = 0.42). Acute cardiac rejection episodes were more frequent in HTx than in HKTx patients (0.04 +/- 0.09 vs 0.02 +/- 0.04 ARE/100 patient-days; p = 0.07). Incidence of infection was comparable (0.3 +/- 0.2 vs 0.5 +/- 0.4 infection/100 patient-days). Freedom from transplant vasculopathy was 100% in the HKTx group compared with 71% in the HTx group after 4 years (p = 0.04). CONCLUSIONS: Tacrolimus-based immunosuppression yields promising long-term results in HKTx and HTx. The incidence of transplant vasculopathy seems to be lower after HKTx than after HTx. If these results are secondary to a protective effect of tacrolimus-induced tolerance or of tolerance-associated co-transplantation they will need to be investigated in prospective multicenter trials.
The goal of the present study was to examine how recruiting/suppressing degrees of freedom affects the (differential) stability of two rhythmic perception-action patterns. In particular, participants synchronized either adduction-on-the-beat or abduction-on-the-beat movements of the right index finger with an auditory metronome. The stability of both patterns as performed in the horizontal plane was predicted to depend on the utilization, or recruitment, of the vertical plane of motion. Movements of the index finger were either free or physically restricted to the horizontal plane. The results showed that in the free condition, the vertical plane was recruited more in the more stable pattern (abduction-on-the-beat) than in the less stable pattern (adduction-on-the-beat). In the constrained condition, abduction-on-the-beat pattern was destabilized, whereas the stability of the adduction-on-the-beat pattern was preserved. These results suggest that the recruitment of the vertical plane of motion in the abduction-on-the-beat movements brought about an increase in the stability of this pattern. More generally, the trade-off between the stability of coordination patterns in the horizontal plane is based on a self-organizing process of recruitment in which neuromuscular factors are an intrinsic aspect.
BACKGROUND: Cutaneous leishmaniasis (CL), rare in the first Gulf War, is common in American troops serving in Operation Iraqi Freedom. Awareness of the clinical features and treatment options of CL would benefit clinicians who may encounter soldiers, as well as civilians, returning from the Middle East with skin lesions. OBJECTIVE: Our purpose was to describe our clinical experience in treating soldiers with CL. METHODS: From December 2003 through June 2004, approximately 360 of an estimated 20,000 soldiers returning from a yearlong deployment in Iraq with skin lesions suspected of being CL were examined by dermatologists. We summarized CL diagnoses, laboratory evaluations, and treatments, including localized heat therapy (ThermoMed model 1.8; ThermoSurgery Technologies, Inc, Phoenix, Ariz), oral fluconazole, cryotherapy, and itraconazole. RESULTS: Among 237 soldiers diagnosed with CL, 181 had one or more laboratory confirmations, most by Giemsa-stained lesion smears and polymerase chain reaction (PCR). PCR was positive for all 122 smear-positive and 26 biopsy-positive lesions and all 34 smear negative and all 3 biopsy-negative cases. Primary outpatient treatments, including ThermoMed (n = 26), oral fluconazole (n = 15), cryotherapy (n = 4), and itraconazole (n = 2), were safe and tolerable. Treatment failure occurred in 2 fluconazole recipients and was suspected in 1 ThermoMed and 2 fluconazole recipients. Seventy-two soldiers elected no treatment. LIMITATION: This was a retrospective study. CONCLUSION: Approximately 1% of Ft Campbell troops returning from Iraq were diagnosed with CL, most by laboratory confirmation. PCR appeared to be the most useful diagnostic technique. Among outpatient treatments, ThermoMed and cryotherapy had favorable safety and efficacy profiles.
BACKGROUND: Most seriously wounded US Army casualties from the Iraqi theater of operations come through Walter Reed Army Medical Center on their return to the United States. General surgery and orthopaedic surgery services have developed a multidisciplinary team approach to triage and treatment of incoming casualties. STUDY DESIGN: Prospective database of returning casualties to Walter Reed Army Medical Center from Operation Iraqi Freedom (OIF) from March 1 to July 1, 2003. RESULTS: Of 294 casualties seen, 119 were triaged to inpatient status and treated within 1 hour of arrival; mean age 26.6 +/- 6.2 years (range 23 to 37). Time from original battlefield injury was a mean of 8 days (range 3 to 28 days). Forty-six (39%) sustained gunshot wounds, 37 (31%) sustained blast and shrapnel injuries, and 41 (34%) had blunt/motor vehicle collision mechanisms. There were a total of 184 wounded locations in these 119 casualties; of these, there were 29 head and neck, 25 chest, 20 abdomen, 74 lower extremity, and 36 upper extremity. Twenty-eight casualties (23%) required emergent surgical procedures on the night of arrival. Another 30 (25%) required an urgent surgical procedure within 48 hours of arrival. CONCLUSIONS: Followup surgical procedures were urgently or emergently required in 43% of admitted battlefield casualties from OIF on transfer to Level V care in the continental United States. The injury pattern of wounds from this engagement is described. The Walter Reed Army Medical Center system of incoming battlefield casualty evaluation using multidisciplinary teams is successful in expediting care and ensuring evaluation of the full range of potential injuries.
Human intervertebral disc specimens were tested to determine the regions of largest maximum shear strain (MSS) experienced by disc tissues in each of three principal displacements and three rotations, and to identify the physiological rotations and displacements that may place the disc at greatest risk for large tissue strains and injury. Tearing of disc annulus may be initiated by large interlamellar shear strains. Nine human lumbar discs were tagged with radiographic markers on the endplates, disc periphery and with a grid of wires in the mid-transverse plane and subjected to each of the six principal displacements and rotations. Stereo-radiographs were taken in each position and digitized for reconstruction of the three-dimensional position of each marker. Maximum tissue shear strains were calculated from relative marker displacements and normalized by the input displacement or rotation. Lateral shear, compression, and lateral bending were the motions that produced the mean (95% confidence interval) largest mean MSS of 9.6 (0.7)%/mm, 9.0 (0.5)%/mm, and 5.8 (1.6)%/ degrees , respectively, and which occurred in the posterior, posterolateral and lateral peripheral regions of the disc. After taking into account the reported maximum physiological range of motion for each degree of freedom, motions producing the highest physiological MSS were lateral bending (57.8 (16.2)%) and flexion (38.3 (3.3)%), followed by lateral shear (14.4 (1.1)%) and compression (12.6 (0.7)%).
Functional magnetic resonance imaging (fMRI) experiments investigating cortical activity while controlling task performance are difficult to conduct due to the high magnetic field environment and a lack of compatible measurement tools. We describe a method to measure the generation of isometric shoulder and elbow torques with a six-degrees-of-freedom (DOF) load cell during an event-related fMRI study. Feasibility of this method is demonstrated by finding cortical activity on the motor cortices in a participant during an event-related study of shoulder abduction and elbow flexion. The described methodology permits researchers to control and measure intersubject and intrasubject motor task performance during event-related brain imaging.
An electromechanical system is described that comprises a cam and two linear displacement transducers for measuring two-degree of freedom. This is aimed at quantifying the extent and pattern of both transverse rotation and longitudinal translation that takes place during amputee gait at what is sometimes termed a "torque-shock absorbing adapter" located between the prosthetic socket and foot. Both types of motion are measured independently by mounting the cam around the adapter and the two transducers orthogonal to one another with their spring loaded plungers moving separately against the cam's perimeter and distal, flat face. The cam geometry should be an arc of a spiral and not a circle for the angular displacement measurement to be linear in response to rotation. Over a range of +/-18 degrees for transverse rotation the maximum deviation of the ideal cam geometry away from an arc of a circle is less than +/-0.5% of the transducers' 10 mm stroke. The transducer's linearity is +/-2% and it could therefore be assumed that this would be the dominant source of error. The theoretical predictions are supported by the calibration results, in which the pattern of errors that are found in the transducers' calibration can also be seen in the calibration of the cam.
A novel robotic articulator that reproduced a six-degree-of-freedom jaw movement was developed and tested. A precise six-axis micro-positioning stage was employed for this articulator. A high-resolution jaw-tracking device measured the functional jaw movement of the patient and a six-axis micro-positioning stage reproduced recorded jaw movement data. A full veneer crown restoration was fabricated with this articulator system. A working cast was mounted on the positioning stage of the articulator. An occlusal table with soft wax was attached on the cast tooth die, and the jaw movements were reproduced to create a functionally generated path on the occlusal table. The finished occlusal record was used to obtain the wax pattern for the crown. In this subject, no intra-oral occlusal adjustment was necessary for setting the finished full veneer crown. Since this articulator could perform a precise reproduction of the dynamic jaw motion during the functional jaw movement, this system has potential to improve accuracy of the prosthetic teeth occlusion.
Quantitative longitudinal brain magnetic resonance (MR) studies may be confounded by scanner-related drifts in voxel sizes. Total intracranial volume (TIV) normalisation is commonly used to correct serial cerebral volumetric measurements for these drifts. We hypothesised that automated rigid-body registration of whole brain incorporating automatic scaling correction might also correct for such fluctuations, and might be a more practical alternative. Twenty-three subjects (12 patients with Alzheimer's disease [AD] and 11 controls) had at least two serial T1-weighted volumetric brain MR scans. Ten scans from the control subjects were artificially scaled (stretched) by 1.5, 3.0, 4.6 and 6.1%. A 9-degrees-of-freedom (9dof) registration was used to register the scaled scans back onto the original scans and corresponding scaling factors compared to TIV measurements. A further nine 1-year repeat scans from the AD subjects were artificially scaled and registered (9dof) to baseline. The two correction methods were further assessed using multiple serial scans for each of the 23 subjects (resulting in 49 scan pairs). All serial scans were registered (9dof) to baseline. TIV was measured on all scans. It was found that the 9dof registration successfully recovered the artificially generated scaling changes. Scaling correction using 9dof registration did not alter the amount of brain atrophy measured over the 1-year period in the AD subjects. The 9dof volume scaling factors were very similar to the TIV ratios (repeat TIV over baseline TIV), but less variable (p < 0.001), in both artificial and 'real' scenarios. In the latter, the volume scaling factors allowed identification of two time-points in which a 3% change in voxel size had occurred. Both the 9dof brain registration and TIV correction were successfully able to correct for these fluctuations. Significant shifts in voxel size are a problem in longitudinal brain imaging studies. It is important that such changes are adjusted for: 9dof registration, which is automated and computationally inexpensive, may be superior to the more labour-intensive TIV correction for this purpose.
In the statistical analysis of fMRI data, the parameter of primary interest is the effect of a contrast; of secondary interest is its standard error, and of tertiary interest is the standard error of this standard error, or equivalently, the degrees of freedom (df). In a ReML (Restricted Maximum Likelihood) analysis, we show how spatial smoothing of temporal autocorrelations increases the effective df (but not the smoothness of primary or secondary parameter estimates), so that the amount of smoothing can be chosen in advance to achieve a target df, typically 100. This has already been done at the second level of a hierarchical analysis by smoothing the ratio of random to fixed effects variances (Worsley, K.J., Liao, C., Aston, J.A.D., Petre, V., Duncan, G.H., Morales, F., Evans, A.C., 2002. A general statistical analysis for fMRI data. NeuroImage, 15:1-15); we now show how to do it at the first level, by smoothing autocorrelation parameters. The proposed method is extremely fast and it does not require any image processing. It can be used in conjunction with other regularization methods (Gautama, T., Van Hulle, M.M., in press. Optimal spatial regularisation of autocorrelation estimates in fMRI analysis. NeuroImage.) to avoid unnecessary smoothing beyond 100 df. Our results on a typical 6-min, TR = 3, 1.5-T fMRI data set show that 8.5-mm smoothing is needed to achieve 100 df, and this results in roughly a doubling of detected activations.