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PubMed1995

Prospective assessment of an artificial neural network for the detection of peripheral vascular disease from lower limb pulse waveforms.

The diagnostic performance of an artificial neural network pulse classification system for the detection of peripheral vascular disease was investigated prospectively. Lower limb photoelectric plethysmographic pulses, and Doppler ankle/brachial pressure index (ABPI) measurements (pre- and post-exercise) were obtained from 200 patients referred to a vascular investigation laboratory. A single toe pulse was processed and used as input data to a neural network which had been trained previously with a set of pulses from 100 legs. The neural network outputs represented the diagnostic arterial disease classifications defined by the ABPI. From the 200 patients entered prospectively, 266 legs were available for neural network assessment. A network sensitivity of 92% and specificity of 63% were achieved with a diagnostic accuracy of 80%. By using a higher confidence for the classification decision a small, but insignificant overall improvement was obtained. When a borderline classification was introduced 100% sensitivity and 100% negative predictive value were obtained, though 31% of legs were unclassifiable. Nevertheless, the very high sensitivity and negative predictive value could make this quick and simple technique the one of choice for the first stage in screening large numbers of subjects.

Adult↗
PubMed1991

Recognition of synthetic speech by hearing-impaired elderly listeners.

The Modified Rhyme Test (MRT), recorded using natural speech and two forms of synthetic speech, DECtalk and Votrax, was used to measure both open-set and closed-set speech-recognition performance. Performance of hearing-impaired elderly listeners was compared to two groups of young normal-hearing adults, one listening in quiet, and the other listening in a background of spectrally shaped noise designed to simulate the peripheral hearing loss of the elderly. Votrax synthetic speech yielded significant decrements in speech recognition compared to either natural or DECtalk synthetic speech for all three subject groups. There were no differences in performance between natural speech and DECtalk speech for the elderly hearing-impaired listeners or the young listeners with simulated hearing loss. The normal-hearing young adults listening in quiet out-performed both of the other groups, but there were no differences in performance between the young listeners with simulated hearing loss and the elderly hearing-impaired listeners. When the closed-set identification of synthetic speech was compared to its open-set recognition, the hearing-impaired elderly gained as much from the reduction in stimulus/response uncertainty as the two younger groups. Finally, among the elderly hearing-impaired listeners, speech-recognition performance was correlated negatively with hearing sensitivity, but scores were correlated positively among the different talker conditions. Those listeners with the greatest hearing loss had the most difficulty understanding speech and those having the most trouble understanding natural speech also had the greatest difficulty with synthetic speech.

Adult↗
PubMed2002

Learning intravenous cannulation: a comparison of the conventional method and the CathSim Intravenous Training System.

Intravenous cannulation is a nursing procedure carried out in some clinical units that may induce trauma and discomfort. Nurses should be well prepared before practising the procedure with clients. Conventionally, a plastic arm was used for practice but, with innovative developments in technology, a computer program called the CathSim Intravenous Training System (CathSim ITS) is available for this purpose. This study was conducted to compare the effectiveness of learning using a plastic arm with the CathSim ITS. Twenty-eight nurses were divided into two groups and randomly assigned to the two different methods: plastic arm (control group) or CathSim ITS (experimental group). Both groups were provided with 1 hour of theory input and 2 hours of nursing laboratory work. When the nurses felt ready to practise on clients, their performances were assessed by researchers with an intravenous cannulation qualification using a validated checklist. Prior to the assessment, trait and state anxiety levels were measured using the State-Trait Anxiety Inventory (Hong Kong Chinese adaptation) to check whether anxiety would affect the performance. Following the assessment, a semi-structured interview was conducted to reveal my knowledge acquired through using the selected method. Both the control and CathSim ITS groups demonstrated a high success rate, scoring 100% and 92.86%, respectively, with their first client. The semi-structured interviews revealed that the CathSim ITS group appreciated several features of their assigned method. However, there is room for further development.

Catheterization, Peripheral↗
PubMed1999

Effect of catheter placement on 3-D velocity profiles in curved tubes resembling the human coronary system.

Novel measurement techniques based on intravenous ultrasound (IVUS) technology ('IVUS-Flowmetry') require the location of a catheter inside the coronary bed. The present study quantifies disturbances in the 3-D velocity profile induced by catheter placement inside a tube, applying computational fluid dynamics. Two curved, circular meshes (radius K = 0.025 m and K = 0.035 m) with and without a catheter inside the lumen were applied. The catheter was located at the inner curve, the outer curve and at the top position. Boundary conditions were: no slip on the wall, zero stress at the outlet, uniform inflow with entrance velocities of 0.1, 0.2 and 0.4 m/s. Curvature-associated centrifugal forces shifted the maximal velocity to the outer curve and introduced two symmetrical vortices. Additional catheter placement redistributed the 3-D axial velocity field away from the catheter, which was accompanied by the appearance of multiple low-strength vortices. In addition, peak axial velocity increased, peak secondary velocities decreased, axial pressure drop increased and shear stress increased. Flow calculations simulated to resemble IVUS-based flowmetry changed by only 1% after considering secondary velocity. In conclusion, placement of a catheter inside a curved tube resembling the human coronary system changes the velocity field and reduces secondary patterns. The present study supports the usefulness of catheter-based flowmetry during resting flow conditions. During hyperemic flow conditions, flow measurements might be accompanied by large axial pressure drops because the catheter, itself, might act as a significant stenosis.

Blood Flow Velocity↗
PubMed1993

Development of a neural network screening aid for diagnosing lower limb peripheral vascular disease from photoelectric plethysmography pulse waveforms.

An artificial neural network (ANN) was trained to classify photoelectric plethysmographic (PPG) pulse waveforms for the diagnosis of lower limb peripheral vascular disease (PVD). PPG pulses from the lower limbs, and pre- and post-exercise Doppler ultrasound ankle to brachial systolic blood pressure ratio measurements were obtained from patients referred to a vascular investigation laboratory. A single PPG pulse from the big toe of each leg was processed and normalized, and used as input data to the ANN. The ANN outputs represented the diagnostic classifications (normal, significant PVD and major PVD) and the ANN was trained with the ankle to brachial pressure indices (ABPI). The ANN structure consisted of an input layer (50 neuron units from the PPG pulse input), a single hidden layer (15 neurons) and an output layer (3 neurons for the PVD diagnoses). The back-propagation learning algorithm was used to train the ANN for 500 epochs with a PPG training set of pulses from 100 legs. Test data for network assessment comprised pulses from a further 50 legs (20 normal and 30 PVD, of which 15 were categorized as having major disease). A network sensitivity of 93% and specificity of 85% was achieved with respect to the Doppler ABPI standard, giving a diagnostic accuracy of 90%. The results of this study indicate that a neural network can be trained to distinguish between PPG pulses from normal and diseased lower limb arteries. The simplicity of PPG measurement and neural network classification holds promise for the screening of lower limb arterial PVD.

Humans↗
PubMed2002

Surgical indications in idiopathic splenomegaly.

HYPOTHESIS: The incidence of primary lymphoma of the spleen in patients with idiopathic splenomegaly is significant. DESIGN: Retrospective review of all patients referred to a general surgical service for splenectomy. SETTING: A large tertiary care hospital. PATIENTS: Between 1994 and 2001, 86 nontrauma patients were referred for splenectomy. Of these, 18 had idiopathic splenomegaly despite prior workup with computed tomography, peripheral smear, bone marrow biopsy, and laboratory testing. All patients were symptomatic and displayed varying degrees of cytopenia. INTERVENTION: All 18 patients underwent open splenectomy for diagnosis and treatment of their cytopenias. MAIN OUTCOME MEASURE: Incidence of lymphoma in the pathologic specimens. RESULTS: The mean size of the spleens was 21 cm (range, 14-34 cm) and mean weight was 996 g (range, 320-1840 g). In all 18 patients, the surgical specimen provided a diagnosis. Sarcoidosis was discovered in 4 patients, and 1 patient had Castleman disease. Six patients with the benign diagnosis of hypersplenism received no further interventions, and the cytopenias resolved in all 6 cases. The 7 remaining patients (39%) were diagnosed with lymphoma. Five had marginal zone lymphoma, and 2 had a more aggressive B-cell lymphoma. Three patients required chemotherapy, but 4 are still in remission since their splenectomies and show no evidence of active disease. The mean follow-up was 20 months. CONCLUSIONS: A high percentage of patients with splenomegaly of unknown etiology will have primary lymphoma of the spleen. Splenectomy is both diagnostic and therapeutic and should be considered for all patients with idiopathic splenomegaly.

Adult↗
PubMed1999

Reliability of nerve conduction studies among active workers.

Nerve conduction studies play an important role in clinical practice and research. Given their widespread use, reliability of tests merits careful attention. We assessed interexaminer and intraexaminer reliability of median and ulnar sensory nerve measures of amplitude, onset latency, and peak latency. In a two-phase cross-sectional study, two examiners tested 158 workers. Reliability was assessed with intraclass correlations (ICC) and kappa statistics. Median nerve measures were more reliable (ICC range, 0.76 to 0.92) than ulnar measures (ICC range, 0.22 to 0.85). Ulnar-onset latencies had the worst reliability. The median-ulnar peak latency difference was a particularly stable measure (ICC range, 0.79 to 0.92). The median-ulnar peak latency difference had high interexaminer reliability (kappa range, 0.71 to 0.79) for normal tests defined by cut points of 0.8 ms and 0.5 ms. Intraexaminer reliability was higher with the 0.8-ms cut point (kappa = 0.90 and kappa = 0.85 for examiners 1 and 2, respectively). Rather than absolute cut points to describe normality, a more rational interpretation of results can be made with ordered categories or continuous measures.

Adult↗
PubMed1999

Bone healing and mineralization, implant corrosion, and trace metals after nickel-titanium shape memory metal intramedullary fixation.

Its shape memory effect, superelasticity, and good wear and damping properties make the NiTi shape memory alloy a material with fascinating potential for orthopedic surgery. It provides a possibility for making self-locking, self-expanding, and self-compressing implants. Problems, however, may arise because of its high nickel content. The purpose of this work was to determine the corrosion of NiTi in vivo and to evaluate the possible deleterious effects of NiTi on osteotomy healing, bone mineralization, and the remodeling response. Femoral osteotomies of 40 rats were fixed with either NiTi or stainless steel (StSt) intramedullary nails. The rats were killed at 2, 4, 8, 12, 26, and 60 weeks. Bone healing was examined with radiographs, peripheral quantitative computed tomography, (pQCT) and histologically. The corrosion of the retrieved implants was analyzed by electron microscopy (FESEM). Trace metals from several organs were determined by graphite furnace atomic absorption spectrometry (GF-AAS) or by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were more healed bone unions in the NiTi than in the StSt group at early (4 and 8 weeks) time points. Callus size was equal between the groups. The total and cortical bone mineral densities did not differ between the NiTi and StSt groups. Mineral density in both groups was lower in the osteotomy area than in the other areas along the nail. Density in the nail area was lower than in the proximal part of the operated femur or the contralateral femur. Bone contact to NiTi was close. A peri-implant lamellar bone sheet formed in the metaphyseal area after 8 weeks, indicating good tissue tolerance. The FESEM assessment showed surface corrosion changes to be more evident in the StSt implants. There were no statistically significant differences in nickel concentration between the NiTi and StSt groups in any of the organs. NiTi appears to be an appropriate material for further intramedullary use because it has good biocompatibility in bone tissue.

Animals↗
PubMed2001

Sequential electroelution and mass spectroscopic identification of intact sodium dodecyl sulfate-proteins labeled with 5(6)-carboxyfluorescein-N-hydroxysuccinimide ester.

A gel electrophoresis apparatus capable of scanning the migration path fluorometrically and of computer-directed electroelution of bands was applied to the mass spectrometric identification of sequentially electroeluted 5(6)-carboxyfluorescein-N-hydrosuccinimide ester (FLUOS)-labeled sodium dodedyl sulfate (SDS)-proteins. The masses of four electroeluted SDS-proteins under study determined by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) spectrometry are changed by 1% due to their reaction with FLUOS in a 1:5 molar ratio of protein:label, allowing for the identification of the labeled intact proteins on the basis of mass. More importantly, the partial (10 or 50%) derivatization of proteins with FLUOS does not preclude their tryptic hydrolysis, and identification of the protein on the basis of the mass spectrometric analysis of its tryptic peptides. Potentially, the procedure allows for the automated mass spectrometric identification of SDS-proteins globally labeled with FLUOS and electrophoretically separated, without need for any gel sectioning.

Animals↗
PubMed2001

Activation of the inducible nitric oxide synthase pathway contributes to inflammation-induced osteoporosis by suppressing bone formation and causing osteoblast apoptosis.

OBJECTIVE: Osteoporosis is a major clinical problem in chronic inflammatory diseases such as rheumatoid arthritis. The mechanism of bone loss in this condition remains unclear, but previous studies have indicated that depressed bone formation plays a causal role. Since cytokine-induced nitric oxide (NO) production has been shown to inhibit osteoblast growth and differentiation in vitro, this study was undertaken to investigate the role of the inducible NO synthase (iNOS) pathway in the pathogenesis of inflammation-mediated osteoporosis (IMO) by studying mice with targeted inactivation of the iNOS gene (iNOS knockout [iNOS KO] mice). METHODS: IMO was induced in wild-type (WT) and iNOS KO mice by subcutaneous injections of magnesium silicate. The skeletal response was assessed at the tibial metaphysis by measurements of bone mineral density (BMD), using peripheral quantitative computed tomography, by bone histomorphometry, and by measurements of bone cell apoptosis. RESULTS: NO production increased 2.5-fold (P < 0.005) in WT mice with IMO, but did not change significantly in iNOS KO mice. Total BMD values decreased by a mean +/- SEM of 14.4+/-2.0% in WT mice with IMO, compared with a decrease of 8.6+/-1.2% in iNOS KO mice with IMO (P < 0.01). Histomorphometric analysis confirmed that trabecular bone volume was lower in WT mice with IMO compared with iNOS KO mice with IMO (16.2+/-1.5% versus 23.4+/-2.6%; P < 0.05) and showed that IMO was associated with reduced bone formation and a 320% increase in osteoblast apoptosis (P < 0.005) in WT mice. In contrast, iNOS KO mice with IMO showed less inhibition of bone formation than WT mice and showed no significant increase in osteoblast apoptosis. CONCLUSION: Inducible NOS-mediated osteoblast apoptosis and depressed bone formation play important roles in the pathogenesis of IMO.

Animals↗
PubMed2002

Bone density of the human talus does not increase with the cartilage degeneration score.

Osteoarthritis (OA) is a common, disabling condition of synovial joints that can eventually lead to reduced, or lost, mobility. It is characterized by both articular cartilage degeneration and subchondral bone changes. However, a cause-and-effect relationship between the two tissues remains controversial. Increased subchondral bone density has been associated with early degenerative changes in the cartilage of knee, hip, and finger joints-joints in which progressive changes to OA are common. In contrast, the ankle joint is known to exhibit early cartilage changes, but is not prone to the development of OA. In the present study, it was found that cartilage degeneration on the talus is not associated with an increase in bone density, as assessed through peripheral quantitative computed tomography (pQCT).

Adolescent↗
PubMed2003

Increased bone mineral density in the femora of GDF8 knockout mice.

GDF8 (myostatin), a member of the transforming growth factor (TGF)-beta superfamily of secreted growth and differentiation factors, is a negative regulator of skeletal muscle growth. GDF8 knockout mice have approximately twice the skeletal muscle mass of normal mice. The effects of increased muscle mass on bone modeling were investigated by examining bone mineral content (BMC) and bone mineral density (BMD) in the femora of female GDF8 knockout mice. Dual-energy X-ray absorptiometry (DEXA) densitometry was used to measure whole-femur BMC and BMD, and pQCT densitometry was used to calculate BMC and BMD from cross-sections taken at two different locations: the midshaft and the distal metaphysis. The DEXA results show that the knockout mice have significantly greater femoral BMD than normal mice. The peripheral quantitative computed tomography (pQCT) data indicate that the GDF8 knockout mice have approximately 10% greater cortical BMC (P =.01) at the midshaft and over 20% greater cortical BMC at the metaphysis (P <.001). Likewise, knockouts show approximately 10% greater cortical thickness (P <.001) and significantly greater cortical BMD (P <.001) at both locations. These results suggest that inhibitors of GDF8 function may be useful pharmacological agents for increasing both muscle mass and BMD.

Absorptiometry, Photon↗
PubMed2003

Cell and organ printing 1: protein and cell printers.

We have developed several devices for positioning organic molecules, molecular aggregates, cells, and single-cell organisms onto solid supports. These printers can create stable, functional protein arrays using an inexpensive technology. The cell printer allows us to create cell libraries as well as cellular assemblies that mimic their respective position in organs. The printers are derived from commercially available ink-jet printers that are modified to dispense protein or cell solutions instead of ink. We describe here the modifications to the print heads, and the printer hardware and software that enabled us to adapt the ink-jet printers for the manufacture of cell and protein arrays. The printers have the advantage of being fully automated and computer controlled, and allow for the high-throughput manufacture of protein and cell arrays.

Animals↗
PubMed2003

Cell and organ printing 2: fusion of cell aggregates in three-dimensional gels.

We recently developed a cell printer (Wilson and Boland, 2003) that enables us to place cells in positions that mimic their respective positions in organs. However, this technology was limited to the printing of two-dimensional (2D) tissue constructs. Here we describe the use of thermosensitive gels to generate sequential layers for cell printing. The ability to drop cells on previously printed successive layers provides a real opportunity for the realization of three-dimensional (3D) organ printing. Organ printing will allow us to print complex 3D organs with computer-controlled, exact placing of different cell types, by a process that can be completed in several minutes. To demonstrate the feasibility of this novel technology, we showed that cell aggregates can be placed in the sequential layers of 3D gels close enough for fusion to occur. We estimated the optimum minimal thickness of the gel that can be reproducibly generated by dropping the liquid at room temperature onto a heated substrate. Then we generated cell aggregates with the corresponding (to the minimal thickness of the gel) size to ensure a direct contact between printed cell aggregates during sequential printing cycles. Finally, we demonstrated that these closely-placed cell aggregates could fuse in two types of thermosensitive 3D gels. Taken together, these data strongly support the feasibility of the proposed novel organ-printing technology.

Animals↗
PubMed2003

Effect of minodronic acid (ONO-5920) on bone mineral density and arthritis in adult rats with collagen-induced arthritis.

OBJECTIVE: To study the effect of minodronic acid (ONO-5920) on bone loss and arthritis in rats with collagen-induced arthritis (CIA) treated according to 2 different schedules. METHODS: Four groups of female Sprague-Dawley rats (7 months old) were studied: rats without CIA treated with vehicle (controls), CIA rats treated with vehicle (CIA-V), CIA rats treated therapeutically with minodronic acid (CIA-T), and CIA rats treated prophylactically with minodronic acid (CIA-P). Minodronic acid was administered orally at 0.2 mg/kg 3 times a week, beginning 2 weeks after initial sensitization in the CIA-T rats and beginning the day after initial sensitization in the CIA-P rats. Bone mineral density (BMD) was measured by peripheral quantitative computed tomography in the proximal metaphysis and diaphysis of the tibia every 2 weeks until week 8, when the rats were killed. The BMD and bone microstructure of the excised femur were evaluated by dual x-ray absorptiometry and microfocal computed tomography, respectively. Histomorphometry of the proximal tibia was also performed. RESULTS: In CIA-P rats, the incidence of arthritis and the severity of posterior limb swelling were reduced early after sensitization, and the decrease in BMD was prevented throughout the observation period. Bone and joint destruction evaluated by radiography of the foot was reduced in CIA-P rats. The eroded surface was reduced and the microstructure was maintained in CIA-P rats compared with CIA-V rats. The mineral apposition and bone formation rates were not reduced in the CIA-P rats. In CIA-T rats, however, the inflammation was not suppressed and the inhibitory effect on bone loss was smaller than that in CIA-P rats. CONCLUSION: Minodronic acid suppressed the decrease in BMD and the deterioration of the bone microstructure caused by arthritis. Prophylactic administration of minodronic acid had a preventive effect on arthritis at the early stage, although not throughout the observation period.

Animals↗
PubMed1990

Personal computer interface and software for the ZONAX microscope attachment controller.

We describe the hardware and software of a general-purpose interface that permits a personal computer (PC) running MS-DOS to control cytometric devices, e.g., a scanning stage, shutters, and focus motor attached to a microscope. This note explains how to use the interface to convert the ZONAX microscope attachment controller from 8080-based hardware control to PC-based control.

Computer Peripherals↗
PubMed1996

Prediction of fracture load at different skeletal sites by geometric properties of the cortical shell.

Quantitative bone assessment today is primarily based on the analysis of bone mineral density (BMD). The geometric properties of bone, which are an important parameter for skeletal strength, are generally not considered in the routine clinical assessment of osteoporosis. This study combined the geometric properties and the BMD values determined by peripheral quantitative computed tomography (pQCT) at the distal radius and at the femoral neck to predict fracture loads of the radius, femur, and lumbar vertebrae of 20 cadavers. Generalized osteopenia reduced the fracture loads at all three sites (p < 0.001). The strength of the radius and the femoral neck could best be predicted by considering either the second moment of inertia and trabecular BMD (R = 0.93) or the moment of inertia and the cortical BMD (R = 0.91). The geometric properties at the distal radius were highly correlated with the fracture load at the same skeletal site (R = 0.89) and were also used to estimate the fracture risk at the lumbar vertebrae (R = 0.75) and at the femoral neck (R = 0.87). We conclude that both geometry and density contribute substantially to the strength of the skeleton. The screening for osteoporosis and the prediction of fracture risk can be improved, therefore, by an additional consideration of the geometric properties of the cortex.

Aged↗
PubMed1996

In vivo reproducibility of three-dimensional structural properties of noninvasive bone biopsies using 3D-pQCT.

Trabecular bone architecture is one of the main factors influencing the mechanical behavior of cancellous bone. To assess the three-dimensional trabecular microstructure of intact bones, we introduced the concept of noninvasive bone biopsy, a method to assess and analyze cancellous bone based upon three-dimensional peripheral quantitative computed tomography in vivo (3D-pQCT). The aim of this work was to demonstrate the potential of noninvasive bone biopsies as a basis for structural and mechanical analysis of trabecular bone in the process of rapid bone loss. A group of six healthy young male volunteers was measured to provide data on the reproducibility of structural parameters. Baseline and 1-month follow-up measurements were performed to provide data on short-term precision of the procedure, and three of the controls were reanalyzed within 3-6 months to estimate long-term precision. Prior to structural evaluation, the baseline and follow-up measurements were repositioned three-dimensionally to ensure matching volumes of interest (VOI). Trabecular bone density (TBD) as well as structural indices were analyzed for all measurements. The VOIs were analyzed morphometrically by evaluating bone volume (BV/TV) and trabecular number (Tb.N) based on a direct three-dimensional approach. Trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) were derived from these two indices. The data of the measurements at 1 month to determine the short-term precision was in excellent agreement with the baseline measurements. The results showed that structural parameters can be reproduced in vivo with a coefficient of variation of less than 0.5%. With a typical spread of 4% for the structural indices within the group of healthy volunteers, an intraclass correlation of better than 0.98 was reached. We conclude that high-resolution 3D-pQCT has the potential to detect structural changes in trabecular bone during therapeutic and diagnostic trials.

Adult↗