A survey on the prevalence and management of hepatitis B after renal transplantation in Asian-Pacific countries

The carrier rate for hepatitis B virus (HBV) varies from 1% to 2% to 10% in Asian-Pacific countries. A survey involving 12 transplant centers from 11 countries in this region showed that 1% to 25% of kidney transplant recipients were infected with HBV, and up to 60% of these subjects showed abnormal liver biochemistry. While nearly all centers tested anti-HBs in potential kidney transplant recipients, HBV vaccination of nonimmune subjects was routine in only 66.7%. One-third of the surveyed units rejected HBsAg-positive subjects as kidney donors, while the others demonstrated differing policies in choosing the respective recipients. Two units (16.7%) excluded HBsAg-positive patients from kidney transplantation, whereas the others only excluded those with severe liver disease. Heterogeneity also applies to the immunosuppressive regimens, the use of HBV DNA in serial monitoring, and the timing of antiviral therapy in HBsAg-positive kidney transplant recipients. The data showed that despite HBV infection being a significant problem in kidney transplantation, there is a lack of uniform management policy, attributable to the clinical complexity and deficiency of research data. Although improvement in clinical outcome is likely with the advent of nucleoside analogue therapy and better monitoring, the financial implications in the adoption of these recent advances remain realistic concerns.     

Applying instance-based techniques to prediction of final outcome in acute stroke

OBJECTIVE: Acute cerebral stroke is a frequent cause of death and the major cause of adult neurological disability in the western world. Thrombolysis is the only established treatment of ischemic stroke; however, its use carries a substantial risk of symptomatic intracerebral hemorrhage. A clinical tool to guide the use of thrombolysis would be very valuable. One of the major goals of such a tool would be the identification of potentially salvageable tissue. This requires an accurate prediction of the extent of infarction if untreated. In this study, we investigate the applicability of highly flexible instance-based (IB) methods for such predictions. METHODS AND MATERIALS: Based on information obtained from magnetic resonance imaging of 14 patients with acute stroke, we explored three different implementations of the IB method: k-NN, Gaussian weighted, and constant radius search classification. Receiver operating characteristics analysis, in particular area under the curve (AUC), was used as performance measure. RESULTS: We found no significant difference (P = 0.48) in performance for the optimal k-NN (k = 164, AUC = 0.814 +/- 0.001) and Gaussian weight (sigma = 0.17, AUC = 0.813 +/- 0.001) implementations, while they were both significantly better (P < 1 x 10(-6) for both) than the constant radius implementation (R = 0.28, AUC = 0.809 +/- 0.001). Qualitative analyses of the distribution of instances in the feature space indicated that non-infarcted instances tends to cluster together while infarcted instances are more dispersed, and that there may not exist a stringent boundary separating infarcted from non-infarcted instances. CONCLUSIONS: This study shows that IB methods can be used, and may be advantageous, for predicting final infarct in patients with acute stroke, but further work must be done to make them clinically applicable.     

Effects of polymerization shrinkage on the interfacial stress at resin-metal joint in denture-base: a non-linear FE stress analysis.

OBJECTIVES: The purpose of this study was to investigate the effects of polymerization shrinkage on stress at the interface between resin and metal in removable dentures. METHODS: Three-dimensional finite element models of a denture-base were studied, which consisted of acrylic occlusal rims with different heights and metal frameworks. A relaxation modulus of 1.5 GPa for the resin and a Young's modulus of 220 GPa for the metal were used as the material properties. Each model was constrained at the edge of the framework on the palatal vault. Surface-to-surface contact elements were used to calculate the interfacial stress in a direction perpendicular to the bond surface under a linear shrinkage ranging from 0.41 to 0.65%. The principal stress within the resin was also calculated. RESULTS: The maximum interfacial and principal stresses within the denture-base increased with resin shrinkage. Under the lowest linear shrinkage, the mean area percentages in the resin-metal joint that showed interfacial tensile stresses over 10 and 20 MPa were 63.4 and 0%, respectively. While under the highest linear shrinkage, these mean area percentages were 98.8 and 38.1%, respectively. Negligible differences in the stresses were shown by occlusal heights. SIGNIFICANCE: The polymerization shrinkage level has a significant influence on the residual stress at the resin-metal interface. Enhancement of the bond strength on the interface can reduce the failure probability at a resin-metal joint.     

A pre-embedding immunogold approach for detection of synaptic endocytic proteins in situ

During the past decade, many molecular components of clathrin-mediated endocytosis have been identified and proposed to play various hypothetical roles in the process [Nat. Rev. Neurosci. 1 (2000) 161; Nature 422 (2003) 37]. One limitation to the evaluation of these hypotheses is the efficiency and resolution of immunolocalization protocols currently in use. In order to facilitate the evaluation of these hypotheses and to understand more fully the molecular mechanisms of clathrin-mediated endocytosis, we have developed a protocol allowing enhanced and reliable subcellular immunolocalization of proteins in synaptic endocytic zones in situ. Synapses established by giant reticulospinal axons in lamprey are used as a model system for these experiments. These axons are unbranched and reach up to 80-100 microm in diameter. Synaptic active zones and surrounding endocytic zones are established on the surface of the axonal cylinder. To provide access for antibodies to the sites of synaptic vesicle recycling, axons are lightly fixed and cut along their longitudinal axis. To preserve the ultrastructure of the synaptic endocytic zone, antibodies are applied without the addition of detergents. Opened axons are incubated with primary antibodies, which are detected with secondary antibodies conjugated to gold particles. Specimens are then post-fixed and processed for electron microscopy. This approach allows preservation of the ultrastructure of the endocytic sites during immunolabeling procedures, while simultaneously achieving reliable immunogold detection of proteins on endocytic intermediates. To explore the utility of this approach, we have investigated the localization of a GTPase, dynamin, on clathrin-coated intermediates in the endocytic zone of the lamprey giant synapse. Using the present immunogold protocol, we confirm the presence of dynamin on late stage coated pits [Nature 422 (2003) 37] and also demonstrate that dynamin is recruited to the coat of endocytic intermediates from the very early stages of the clathrin coat formation. Thus, our experiments show that the current pre-embedding immunogold method is a useful experimental tool to study the molecular mechanisms of synaptic vesicle recycling.     

The influence of prosthetic foot alignment on trans-tibial amputee gait

An optimally aligned prosthesis, as accomplished by the subjective judgment of the prosthetist, guarantees the best quality of gait. Yet, amputees can adapt to a large variety of geometrical configurations of the prosthetic components. Different external rotation angles of the foot in trans-tibial (TT) prostheses were investigated. The study tried to identify (a) the relationship between foot angle and other gait parameters and (b) the compensating pattern of the amputees to excessive external rotation of the foot. Eight (8) TT amputees, fitted with an identical type of prosthesis, were investigated during ambulation. The prosthetic foot was externally rotated as follows: optimal angle (10.94 x degrees +/- 5.21 degrees), optimal angle plus another 18 degrees, and optimal angle plus another 36 degrees. Analysis of gait was performed with the aid of an electronic walkway. Speed of gait, stance and swing time, and foot angle were monitored in 4 runs for each of the three foot angles. Speed of gait remained almost constant in the three tests. Stance and swing time, as well as step length, significantly changed when 36 degrees were added to the optimal foot angle. This foot position significantly influenced inter-legs time difference and symmetry between the legs. During ambulation, prosthetic foot external rotation was decreased by internal rotation of the limb at the hip joint level. It is concluded that TT amputees can maintain an efficient speed of gait even when the prosthetic foot is malpositioned in excessive external rotation. Although such a malalignment significantly influences other gait parameters during walking, amputees are able to adapt themselves by internal rotation of the hip joint in the amputated leg.     

The effectiveness of caloric value of enteral nutrition in patients with major burns

Enteral nutrition as an important component of modern treatment is mandatory for patients suffering from major burns. Regardless of the initial estimation of caloric requirements, actual daily volume of energy consumption may vary depending on the general condition of the patient and the side effects of enteral nutrition. The aim of our study was to investigate the relation between caloric value of enteral nutrition and treatment course. METHODS: The prospective study involved 103 adult patients treated in the Hospital of Kaunas University of Medicine for 2 degrees -3 degrees burns of 10-80% body surface area from 1 January 2001 till 31 December 2003. All patients received enteral nutrition during the acute phase. After the completion of the treatment, caloric value of enteral nutrition was estimated, and patients were divided into two groups: group A received more than 30 kcal/(kg 24 h); and group B, received less than 30 kcal/(kg 24 h). We compared patients' mortality, complication rate, and hospital stay time. RESULTS: The mortality of patients, who enterally received less than 30 kcal/(kg 24 h), was 32.6%, comparing to 5.3% mortality in patients who received 30 or more kcal/(kg 24 h) (p < 0.01). The caloric value of less than 30 kcal/(kg 24 h) increased the frequency of pneumonia by 2.0 times, and the frequency of sepsis by 1.8 times (p < 0.05). The duration of the treatment of survivors in this group was by 12.6 days longer (p = 0.01). CONCLUSIONS: The caloric value of enteral nutrition seems to be associated with patient mortality, complication rate, and treatment duration. The results of the treatment of patients who received more or 30 kcal/(kg 24 h) were much better. Because determined relationship may not be directly causal, further study is needed to determine whether active intervention to improve nutrition could improve outcomes.     

Reliability of cerebral blood volume maps as a substitute for diffusion‐weighted imaging in acute ischemic stroke

Purpose:

To assess the reliability of cerebral blood volume (CBV) maps as a substitute for diffusion‐weighted MRI (DWI) in acute ischemic stroke. In acute stroke, DWI is often used to identify irreversibly injured “core” tissue. Some propose using perfusion imaging, specifically CBV maps, in place of DWI. We examined whether CBV maps can reliably subsitute for DWI, and assessed the effect of scan duration on calculated CBV.

Materials and Methods:

We retrospectively identified 58 patients who underwent DWI and MR perfusion imaging within 12 h of stroke onset. CBV in each DWI lesion's center was divided by CBV in the normal‐appearing contralateral hemisphere to yield relative regional CBV (rrCBV). The proportion of lesions with decreased rrCBV was calculated. After using the full scan duration (110 s after contrast injection), rrCBV was recalculated using simulated shorter scans. The effect of scan duration on rrCBV was tested with linear regression.

Results:

Using the full scan duration (110 s), rrCBV was increased in most DWI lesions (62%; 95% confidence interval, 48–74%). rrCBV increased with increasing scan duration (P < 0.001). Even with the shortest duration (39.5 s) rrCBV was increased in 33% of lesions.

Conclusion:

Because DWI lesions may have elevated or decreased CBV, CBV maps cannot reliably substitute for DWI in identifying the infarct core. J. Magn. Reson. Imaging 2012;36:1083–1087. © 2012 Wiley Periodicals, Inc.