Search

WW a 43 year old Caucasian Hospital Manager, first presented in July 08 complaining of transient mono-ocular visual loss in the right eye. She described sudden onset loss of vision – ‘like a curtain coming across the vision’. She then proceeded to have similar symptoms in the left eye. There was no history of a subsequent headache. The episode would between 30 seconds and 10 minutes and could occur up to 10 times a day. At times, the attack was also associated with some left arm numbness. She was initially reviewed by Dr Vu [ Stroke Consultant] who diagnosed Amaurosis Fugax and started her on standard anti-platelet therapy [combination of Aspirin and Dypyridamole]. She had very little in terms of vascular risk factors [nil hypertensive, minimal alcohol and a life-long non-smoker with a fasting cholesterol 3.12]. Her PMH history consisted of Gilberts’ Syndrome and endometriosis. She also suffered a DVT following a hysterectomy. Her initial investigations of a CT head and carotid duplex were normal.

Hybridisation work carried out between high yielding cultivars ‘BLA 139-1’ and ‘K-30-1’ during 1972 and subsequent evaluation of the progenies at the Cashew Research Station, Madakkathara, Kerala resulted in the evolution of the promising cashew hybrid ‘Poornima’ (H 1593). This hybrid, with upright compact tree habit and intensive branching, has mid-season flowering behaviour. It has desirable nut characters like high nut weight (7.8 g), high shelling percentage (31%) and good export grade (W 210) suitable for industry. It has an annual yield of 14.08 kg/tree/annum. It is moderately susceptible to tea mosquito bug.

Experimental testing and computational modeling are two useful tools for mechanical characterization of biomaterials, providing insight into material stresses and strains and the possibility of mechanical failure and fatigue. Another interesting issue to consider, however, is tissue response to mechanical stress and strain and incorporation of that knowledge into design to create materials that form mechanically effective tissue-material interfaces in vivo. Experimental testing, computational modeling, and tissue response to stress and strain are discussed in the context of enhancing biomaterial design.

For trans-tibial amputees maintenance over time of a quality fit of the prosthesis to the residual limb is an important clinical challenge. The purpose of this research was to compare diurnal and long-term (5 weeks to 6 months) interface stress changes as well as variance in the change in cross-sectional area down the length of the residual limb. If long-term changes were simply accentuated diurnal fluctuations then this result would suggest similar treatment methods should be used for both conditions. Interface pressures and shear stresses at 13 sites and residual limb shape were measured on eight trans-tibial amputee subjects using patellar-tendon-bearing prostheses. Data were collected at diurnal intervals (within the same day at least 5 h apart) as well as at long-term intervals (5, 10, 15, 20, and 25 weeks apart). Absolute diurnal interface stress changes were not significantly different from those at 5-weeks intervals but were significantly smaller than those at 15, 20, and 25-weeks intervals. Mean interface stress changes increased significantly (p

Interface pressures and shear stresses within the socket, in standing and walking, were measured for two unilateral, male, trans-tibial amputee subjects, during two sessions each. The ratios of equal weight-bearing standing stresses to peak walking stresses showed regional variation, ranging from 0.24:1 for pressure over the anterior region to 1.01:1 for resultant interface shear stress over the lateral region. Interface stresses in standing were only moderate predictors of peak walking stresses. The best correlation coefficient between standing in full weight-bearing and peak walking stress was 0.88 for pressure over the lateral region. As the amputees progressed from minimal to full weight-bearing in standing, and then to walking, the interface stresses increased in a nonlinear fashion, consistent with the assumption that the anterior tibia provides much resistance to the bending moment in the sagittal plane during walking.

Transjugular intrahepatic portocaval shunt (TIPS) is performed in patients with symptomatic Budd–Chiari syndrome (BCS) who do not have repairable hepatic veins. We report the case of a patient who had an inferior vena cava (IVC) stent placed previously as part of the management for BCS, and who subsequently required TIPS. The TIPS tract was created through the strut of the previously placed IVC stent; the TIPS stent was placed after dilatation of the liver parenchyma as well as the strut of the IVC stent. This novel technique of “strutplasty” of a previously placed stent as part of TIPS has not been reported in the literature.

Objective. To evaluate the effects of changes in cadence, prosthetic componentry, and time on interface pressures and resultant shear stresses in trans-tibial amputee case studies. Design. Interface stresses were monitored using custom-designed instrumentation at 13 sites on three subjects with unilateral trans-tibial amputation walking with patellar-tendon-bearing prosthetic limbs. Background. Previous studies suggested that week-to-week residual limb changes altered interface stresses more than did alterations in prosthetic alignment. No studies investigating effects of changes in cadence or componentry on interface stress distributions nor comparing their influence with week-to-week changes have been conducted previously. Methods. Five different prosthetic componentry configurations were tested at each of three cadences in four sessions. Data were analysed for the magnitudes and timings of peak pressures and resultant shear stresses as well as corresponding resultant shear angles. Results. None of the three cadences or five componentry configurations consistently induced significantly (P

The distribution of mechanical stress at the interface between a residual limb and prosthetic socket is an important design consideration in lower-limb prosthetics. Stresses must be distributed so that the amputee is stable and comfortable, while avoiding trauma to the tissues of the residual limb. Numerical estimation of the stresses at the interface through finite element (FE) modeling can potentially provide researchers and prosthetists with a tool to aid in the design of the prosthetic socket. This review addresses FE modeling of interface stresses in lower-limb external prosthetics. The modeling methodologies adopted by analysts are described. Verification of FE estimates of interface stress against experimental data by different analysts is presented and the likely sources of error discussed. While the performance of the models is encouraging, there are definite limitations to all of them, necessitating further improvements. Parametric analysis of the sensitivity of interface stress to model parameters provides a tool to identify model weaknesses and to suggest possible refinements. Parametric analyses by different analysts are also presented and potential refinements discussed. Finally, directions for future work in prosthetic FE modeling are suggested.

A software scheme is presented to extract the shapes of tibiae and fibulae from amputee computer tomography (CT) data for use in prosthetic finite element modeling. A snake algorithm is implemented to overcome challenges of bone-soft tissue edge detection common in this application. Means to enhance initial guess contours, ensure contour continuity, overcome point-clustering problems, and handle high-curvature regions are also described. Effectiveness of the algorithm is demonstrated on image data from a unilateral transtibial amputee subject.

A preliminary investigation was conducted to characterize the magnitude and distribution of volume change in transtibial residua at two time intervals: upon prosthesis removal and at 2 week intervals. Six adult male unilateral transtibial amputee subjects, between 0.75 and 40.0 years since amputation, were imaged 10 times over a 35-minute interval with a custom residual limb optical scanner. Volume changes and shape changes over time were assessed. Measurements were repeated 2 weeks later. Volume increase on socket removal for the six subjects ranged from 2.4% to 10.9% (median 6.0% +/- standard deviation 3.6%). Rate of volume increase was highest immediately upon socket removal and decreased with time (five subjects). In four subjects, 95% of the volume increase was reached within 8 minutes. No consistent proximal-to-distal differences were detected in limb cross-sectional area change over time. Limb volume differences 2 weeks apart ranged from -2.0% to 12.6% (0.6% +/- 5.5%) and were less in magnitude than those within a session over the 35-minute interval (five subjects). Multiple mechanisms of fluid movement may be responsible for short-term volume changes, with different relative magnitudes and rates in different amputees.

A mechanical digitizer was developed for use in prosthetics research where measurements of small differences in shape are of interest. Root-mean-square error was 0.075 mm in the radial direction, 0.05 degrees in the tangential direction, and 0.1 mm in the vertical direction. The system has potential use for time-dependent assessment of changes in socket and residuum cast shape, assessment of socket fabrication systems, and development of accurate prosthetic finite element models.

Hypertension is an important cause of cardiovascular morbidity and mortality.We conducted a cross-sectional survey of 314 middle-aged subjects (163 men; age range 40-60 years, mean 49 years) in urban Thiruvananthapuram City. Kerala, to estimate the prevalence of hypertension, examine its correlates, and assess the degree of awareness, treatment, and control of high blood pressure. Blood pressure was measured by a nurse graduate using a mercury column sphygmomanometer and a standardized technique. We used multivariable analyses to examine the sociodemographic and clinical correlates of hypertension. The overall prevalence of hypertension in our sample was 54.5% (men 56.3%, women 52.3%). The factors associated with an increased prevalence of hypertension were higher body-mass index (odds ratio for a value in the top tertile of 2.33, 95% confidence interval: 1.2-4.4), and older age (odds ratio for the age group 55-60 years of 2.65, 95% confidence interval: 1.3-5.6). An occupation involving moderate or greater physical activity was inversely associated with the prevalence of hypertension (odds ratio 0.35, 95% confidence interval 0.13-0.94). Among hypertensives, 39% were aware of the condition, while 29% were treated with blood pressure-lowering medications. Adequate control of elevated blood pressure was achieved in only 30.6% of treated hypertensives. In our community-based sample, over half of all middle-aged individuals were hypertensive, but less than a third were under treatment. Adequate control of hypertension was achieved in less than a third of the treated individuals.These observations re-emphasize the need for hypertension awareness programs targeting the general public and the increased use of opportunistic blood pressure screening, and underscore the importance of measures to increase the knowledge of current guidelines for the detection and treatment of hypertension among healthcare providers.

Single polypropylene microfibers plasma-coated with polymers of different surface charge [N,N-dimethylaminoethyl methacrylate (NN) (positive charge), methacrylic acid (MA) (negative charge), and hexafluoropropylene (HF) (neutral)] were implanted in the subcutaneous dorsum of Sprague-Dawley rats for 5-week intervals. Thee groups of fiber diameters were used: (I) 1.0 to 5.9 microm; (II) 6.0 to 10.9 microm; and (III) 11.0 to 15.9 microm. Fibrous capsule thickness and blood-vessel density (number of vessels within 100 microm of the fiber) were assessed in tissue sections in the planes of microfiber cross-sections. Results from a multifactorial analysis of variance demonstrated statistically significant main effects (p < 0.05) for microfiber diameter but not for surface-charge coating. The mean differences in capsule thickness among the microfiber diameter groups were: between groups II and I: 5.4 microm; between groups III and I: 10.2 microm; and between groups III and II: 4.7 microm. The mean differences in capsule thickness among surface-charge coatings were: between MA and NN: 0.7 microm; between MA and HF: 1.4 microm; and between NN and HF: 0.7 microm. Many of the 1.0 to 5.9 microm-in-diameter fibers had no capsule and no sign of a foreign-body reaction. For the vessel density analysis, neither microfiber diameter nor surface-charge coating had a statistically significant effect. Thus the geometric feature of microfiber diameter was more important than was surface charge relative to fibrous capsule formation but not relative to local vessel density. This ranking of the relative influence of design features in relation to tissue response provides useful information for prioritization in biomaterial design.

A finite element (FE) model of the trans-tibial residual limb and prosthetic socket was developed. The three-dimensional model accounts for shape differences between the socket and residual limb, and incorporates material nonlinearities. Contact, frictional slip, and separation at the limb-socket interface were permitted using automated contact without gap elements. FE estimates of interface stresses after socket donning compared favorably with experimental measurements, suggesting that the model may potentially contribute to improved understanding of interface biomechanics.

When compared with automated contact methods of finite element (FE) analyses, gap elements have certain inherent disadvantages in simulating large slip of compliant materials on stiff surfaces. However, automated contact has found limited use in the biomechanical literature. A non-linear, three-dimensional, geometrically accurate, FE analysis of the trans-tibial limb-socket prosthetic system was used to compare an automated contact interface model with a gap element model, and to evaluate the sensitivity of automated contact to interfacial coefficient of friction (COF). Peak normal stresses and resultant shear stresses were higher in the gap element model than in the automated contact model, while the maximum axial slip was less. Under proximally directed load, compared with automated contact, gap elements predicted larger areas of stress concentration that were located more distally. Gap elements did not predict any relative slip at the distal end, and also transmitted a larger proportion of axial load as shear stress. Both models demonstrated non -linear sensitivity to COF, with larger variation at lower magnitudes of COF. By imposing physical connections between interface surfaces, gap elements distort the interface stress distributions under large slip. Automated contact methods offer an attractive alternative in applications such as prosthetic FE modeling, where the initial position of the limb in the socket is not known, where local geometric features have high design significance, and where large slip occurs under load.

The objective of the research is to determine if principal component analysis (PCA) provides an efficient method to characterise the normative shape of the proximal tibia. Bone surface data, converted to analytical surface descriptions, are aligned, and an auto-associative memory matrix is generated. A limited subset of the matrix principal components is used to reconstruct the bone surfaces, and the reconstruction error is assessed. Surface reconstructions based on just six (of 1452) principal components have a mean root-mean-square (RMS) reconstruction error of 1.05% of the mean maximum radial distance at the tibial plateau. Surface reconstruction of bones not included in the auto-associative memory matrix have a mean RMS error of 2.90%. The first principal component represents the average shape of the sample population. Addition of subsequent principal components represents the shape variations most prevalent in the sample and can be visualised in a geometrically meaningful manner. PCA offers an efficient method to characterise the normative shape of the proximal tibia with a high degree of dimensionality reduction.

Compressive stiffness (CS) of different supporting materials used in prosthetics and orthotics and their static coefficients of friction (COF) with skin and socks were characterized. Materials tested included Spenco, Poron, nylon-reinforced silicone, Soft Pelite, Medium Pelite, Firm Plastazote, Regular Plastazote, and Nickelplast. A displacement-controlled testing device was constructed to assess the CS of 11.1 mm diameter material specimens under cyclic loading (1 Hz) to 220 kPa over 10- and 60-min periods. Results demonstrated local CS ranging from 687 kPa (Poron) to 3,990 kPa (Soft Pelite). To fit the cyclic stress-strain (S-S) data within an error of 4.0 percent full-scale output, the minimum order of fit required for Spenco, Poron, and nylon-reinforced silicone was a third-order polynomial; for Soft Pelite, Medium Pelite, Firm Plastazote, and Regular Plastazote, a second-order polynomial; and for Nickelplast, a linear fit. For all materials, the nonrecovered strains were related to loading time using an exponential fit. A biaxial force-controlled load applicator device was used to assess COF at skin-material, sock-material, and skin-sock interfaces for shear forces of 1 to 4 N applied to a 10.2 x 7.8 mm loading pad. COFs ranged from 0.48 (+/- 0.05) to 0.89 (+/- 0.09). COFs at skin-material interfaces were significantly (p0.05) higher than those at skin-sock interfaces. There was a trend of a higher COF at sock-material interfaces than at skin-sock interfaces. These data are of potential utility in finite element modeling sensitivity analysis of residual limb-prosthetic socket systems or body-orthosis systems to characterize effects of material features on interface pressure and shear stress distributions.

Experimental testing and computational modeling are two useful tools for mechanical characterization of biomaterials, providing insight into material stresses and strains and the possibility of mechanical failure and fatigue. Another interesting issue to consider, however, is tissue response to mechanical stress and strain and incorporation of that knowledge into design to create materials that form mechanically effective tissue-material interfaces in vivo. Experimental testing, computational modeling, and tissue response to stress and strain are discussed in the context of enhancing biomaterial design.

A device designed to measure the forces and moments transmitted through prostheses of persons with lower limb amputation is presented. The sensing unit design is an advancement over previous prosthesis force measurement devices in that it is very thin (19 mm) and lightweight (527.5 g, including signal-conditioning instrumentation). The disk-shaped transducer fits between the socket and socket adapter of a standard modular prosthesis, measuring all six force and moment components at this location. Twelve strain gages were used, configured into six two-arm active Wheatstone bridge circuits. A 6X6 matrix was constructed from calibration data to relate the 6-component bridge-output vector to a 6-component force and moment vector. In a bench-test setting, the sensor was evaluated under typical load combinations encountered during the walking of a person with transtibial amputation (TTA) and shown to have errors less than 7.2% of the full-scale output for each direction. Data collected on a subject with TTA walking at different speeds are presented.

A general method to generate hexahedral meshes for finite element analysis of residual limbs and similar biomedical geometries is presented. The method utilizes skeleton-based subdivision of cross-sectional domains to produce simple subdomains in which structured meshes are easily generated. Application to a below-knee residual limb and external prosthetic socket is described. The residual limb was modeled as consisting of bones, soft tissue, and skin. The prosthetic socket model comprised a socket wall with an inner liner. The geometries of these structures were defined using axial cross-sectional contour data from X-ray computed tomography, optical scanning, and mechanical surface digitization. A tubular surface representation, using B-splines to define the directrix and generator, is shown to be convenient for definition of the structure geometries. Conversion of cross-sectional data to the compact tubular surface representation is direct, and the analytical representation simplifies geometric querying and numerical optimization within the mesh generation algorithms. The element meshes remain geometrically accurate since boundary nodes are constrained to lie on the tubular surfaces. Several element meshes of increasing mesh density were generated for two residual limbs and prosthetic sockets, Convergence testing demonstrated that approximately 19 elements are required along a circumference of the residual limb surface for a simple linear elastic model. A model with the fibula absent compared with the same geometry with the fibula present showed differences suggesting higher distal stresses in the absence of the fibula. Automated hexahedral mesh generation algorithms for sliced data represent an advancement in prosthetic stress analysis since they allow rapid modeling of any given residual limb and optimization of mesh parameters.

8225 AI results in cumulative multi-lineage toxicity. In our previous study of filgrastim and epoetin alfa (G + EPO) with AI in chemo-naive pts, the incidence of neutropenic fever (NF) was 33% and red cell transfusions (PRBC Tx) 40% of cycles. The purpose of the present study was to evaluate safety, hematopoietic effects on progenitors, and efficacy of the new long-acting HGFs Peg-G + DPO in reducing the incidence of NF and PRBC Tx. AI (A 90 mg/m2; I 10 gm/m2) was administered on days 0–3. HGFs were administered SC once per cycle, with DPO (initial dose, 500 mcg) prior to (day 0) and Peg-G (6 mg) post (day 4) completion of AI. Cycles were repeated q 21 days (max 6 cycles). Bone marrow (BM) and peripheral blood progenitor cells were examined in cycle 1. The data for NF and PRBC Tx are shown below for both studies. The median duration of neutropenia during all 6 cycles remained ≤3 days with Peg-G as compared to a progressive increase in the duration with G (days ANC

The mechanical properties of 15 elastomeric liner products used in limb prosthetics were evaluated under compressive, frictional, shear, and tensile loading conditions. All testing was conducted at load levels comparable to interface stress measurements reported on transtibial amputee subjects. For each test configuration, materials were classified into four groups based on the shapes of their response curves. For the 15 liners tested, there were 10 unique classification sets, indicating a wide range of unique materials. In general, silicone gel liners classified within the same groups thus were quite similar to each other. They were of lower compressive, shear, and tensile stiffness than the silicone elastomer products, consistent with their lightly cross-linked, high-fluid content structures. Silicone elastomer products better spanned the response groups than the gel liners, demonstrating a wide range of compressive, shear, and tensile stiffness values. Against a skin-like material, a urethane liner had the highest coefficient of friction of any liner tested, although coefficients of friction values for most of the materials were higher than interface shear:pressure ratios measured on amputee subjects using Pelite liners. The elastomeric liner material property data and response groupings provided here can potentially be useful to prosthetic fitting by providing quantitative information on similarities and differences among products.

A mechanical digitizer was developed for use in prosthetics research where measurements of small differences in shape are of interest. Root-mean-square error was 0.075 mm in the radial direction, 0.05 degrees in the tangential direction, and 0.1 mm in the vertical direction. The system has potential use for time-dependent assessment of changes in socket and residuum cast shape, assessment of socket fabrication systems, and development of accurate prosthetic finite element models.

Bright greenish yellow (BGYF) and blue white (BWF) fluorescences were associated with Aspergillus flavus and A. parasiticus infected maize. The fluorescences were studied spectrofluorometrically, the BGYF exhibiting a peak wave length between 480–485 nm and the BWF between 440–445 nm. Neither fluorescence varied in maize stored under different moistures and temperatures. BWF was similar spectrally to the fluorescence of the endosperm of sound kernels but × 5 20 more intense. The spectrum of BWF was similar to Aflatoxin G 1 or a mixture of aflatoxin B 1 , B 2 , G 1 and G 2 when they were spotted on endosperm tissue. A color reference for BGYF was similar in peak wave length to BGYF. Amsoy soybeans without the seed coat fluoresced with a peak 470–475 nm and the intensity was low compared to BGYF in maize. A fluorescence of maize kernels visually similar to BGYF but not associated with Aspergillus infection or aflatoxin contamination was also investigated. This “false BGY” fluorescence was spectrally similar to the BGYF in infected kernels.