Recurrent type III membranoproliferative glomerulonephritis after kidney transplantation

The first well-documented case of recurrent type III membranoproliferative glomerulonephritis after kidney transplantation is reported in this article. A 48-year-old man was admitted to the hospital because of nephrotic syndrome and moderate renal failure. The renal biopsy showed double-contour images at light microscopy. Electron microscopy revealed electron-dense deposits in the mesangium and in both the subepithelial and subendothelial sides of the basement membrane. Subepithelial deposits were sometimes hump-like and produced an irregular disruption of the lamina densa. A diagnosis of type III membranoproliferative glomerulonephritis was suggested. The patient had a rapid decrease in renal function and received dialysis in 3 months. Three years later, he received a cadaveric kidney transplant, and subsequently recovered normal renal function. Proteinuria appeared after 13 months, and a biopsy of the graft demonstrated recurrence of the original disease. Seven years after transplantation, he returned to hemodialysis.     

Physical properties of ceramides: effect of fatty acid hydroxylation

The structural and thermotropic properties of alpha-hydroxy fatty acid (HFA) and non-hydroxy fatty acid (NFA) ceramides (CER) have been studied using differential scanning calorimetry (DSC) and X-ray diffraction techniques. The DSC of anhydrous HFA-CER shows a single, sharp reversible transition at 95.6 degrees C (delta H = 15.3 kcal/mol). At intermediate hydrations HFA-CER exhibited more complex behavior but at maximum hydration only a single reversible transition is observed at 80.0 degrees C (delta H = 8.5 kcal/mol). X-ray diffraction of hydrated (74% water) HFA-CER at 20 degrees C shows a lamellar structure with a bilayer periodicity d = 60.7 Angstrum; a single wide angle reflection at 4.2 Angstrum is characteristic of hexagonal chain packing. Above the main transition temperature at 91 degrees C, a hexagonal (HII) phase is observed. In contrast, DSC of anhydrous NFA-CER demonstrates two thermal transitions at 81.3 degrees C (delta H = 6.8 kcal/mol) and 85.9 degrees C (delta H = 3.5 kcal/mol). With increasing hydration, both transitions shift towards lower temperatures; at maximum hydration, on heating, the endothermic transitions occur at 72.7 degrees C (delta H = 9.8 kcal/mol) and 81.1 degrees C (delta H = 4.0 kcal/mol). On cooling, there is hysteresis of both transitions. X-ray diffraction of NFA-CER (80% water) at 20 degrees C shows a well-ordered lamellar structure with a bilayer periodicity d = 58.6 Angstrum and three wide-angle reflections at 4.6 Angstrum, 4.2 Angstrum, and 3.8 Angstrum. At 77 degrees C (between the two transitions), again a lamellar structure exists with reduced bilayer periodicity d = 53.1 Angstrum and four wide-angle reflections at 4.6 Angstrum, 4.2 Angstrum, and 3.8 Angstrum are observed. Above the second transition, only a single low angle reflection at 30.0 Angstrum is observed; a diffuse reflection at 4.6 Angstrum is indicative of a melted chain phase. Thus, HFA-CER exhibits a simple phase behavior involving the reversible conversion of a gel phase to a hexagonal phase (L beta-->HII). However, NFA-CER shows a more complex polymorphic phase behavior involving two gel phases.     

Martingales without tears

This pedagogical paper presents a casual introduction to martingales, or fair gambling processes. Our objective is to describe the concept of a martingale and its application to common statistical tests used in the analysis of survival data, but without the mathematical rigor required for formal proofs. We use heuristic arguments to demonstrate that the logrank statistic evaluated over followup time is a fair gambling process, and introduce some mathematical notation and terminology along the way. We then employ the counting process approach to show that the logrank statistic computed over followup time can be expressed as the difference of two martingale transforms, and thus is a martingale. These ideas are first time introduced in the context of a discrete time process, and are then generalized to a continuous time process. With slight modifications, the same idea extends from the logrank to other weighted Mantel-Haenszel statistics computed over time.     

Pressor responses to distension of the ureter in anaesthetised rats: characterisation of a model of acute visceral pain

HIV-associated dementia is a frequent consequence of HIV infection and relates to neuronal damage, possibly as a result of increased neurotoxic kynurenine metabolites. Indoleamine-2,3-dioxygenase (IDO) activity, which regulates kynurenine metabolism, may thus be increased in HIV infection. We measured IDO activity in post-mortem brain tissue from AIDS patients, including a subgroup that exhibited dementia, and age-matched control subjects. IDO activity was increased, but not significantly, in the AIDS group as well as the non-dementia group, compared to controls. Enzyme activity was significantly increased in the dementia group when compared to control values. IDO activity is increased in HIV-associated dementia and is thus likely to increase kynurenine pathway metabolites, such as 3-hydroxykynurenine and quinolinic acid, and elevated levels of these neurotoxins may contribute to the neuronal deficits underlying HIV-associated dementia.     

A randomized study of the influence of perfusion technique and pH management strategy in 316 patients undergoing coronary artery bypass surgery. I. Mortality and cardiovascular morbidity

The impact of perfusion technique and mode of pH management during cardiopulmonary bypass has not been well characterized with respect to postoperative cardiovascular outcome. METHODS: This double-blind, randomized study comparing outcomes after alpha-stat or pH-stat management and pulsatile or nonpulsatile perfusion during moderate hypothermic cardiopulmonary bypass was undertaken in 316 patients undergoing coronary artery bypass operations. RESULTS: Cardiovascular morbidity and mortality were not affected by pH management, and the incidence of stroke (2.5%) did not differ between groups. Overall in-hospital mortality was 2.8%, eight of the nine deaths occurring in the nonpulsatile group (5.1% versus 0.6%; p = 0.018). The incidence of myocardial infarction was 5.7% in the nonpulsatile group and 0.6% in the pulsatile group (p = 0.010), and use of intraaortic balloon pulsation was significantly more common in the nonpulsatile group (7.0% versus 1.9%; p = 0.029). The overall percentage of patients having major complications was also significantly higher in the nonpulsatile group (15.2% versus 5.7%; p = 0.006). Duration of cardiopulmonary bypass, age, and use of nonpulsatile perfusion all correlated significantly with adverse outcome. CONCLUSIONS: Use of pulsatile perfusion during cardiopulmonary bypass was associated with decreased incidences of myocardial infarction, death, and major complications.     

Effect of grain size on the martensitic transformation in NiTi alloy

The effect of grain size on the martensitic transformation in Ni42Ti shape memory alloy has been studied. The kinetics of grain growth has been evaluated and the influence of different grain sizes on the transformation temperatures and the thermodynamic magnitudes has been reported. Image analysis and flow calorimetry techniques have been used. The study shows that grain boundaries favour the martensitic transformation and at the same time obstruct retransformation. Enthalpy and entropy variations are independent of grain size, but elastic energy decreases with the grain size.     

Automated localization of the prostate at the time of treatment using implanted radiopaque markers: technical feasibility

PURPOSE: Prostate movement is a major consideration in the formation of target volumes for conformal radiation therapy of prostate cancer. The goal of this study was to determine the technical feasibility of using implanted radiopaque markers and digital imaging to localize the prostate at the time of treatment, thus allowing for reduction of the margin required for uncertainty in target position. METHODS AND MATERIALS: Radiopaque markers implanted around the prostate prior to treatment are visible on electronic radiographs generated with a portal imager or diagnostic imaging device. The locations of the images of these markers on the digital radiographs were automatically determined by a template-matching algorithm. The coordinates of the markers were found by projecting rays through the marker locations on orthogonal radiographs using a three-dimensional (3D) point-matching algorithm. Prostate and/or patient movement was inferred from the marker displacements. Images generated from known movements of a phantom with implanted markers were tested with this algorithm. Locations of markers from daily images of patients with implanted markers were determined by both manual and automatic techniques to determine the efficacy of automated localization on typical clinical images. RESULTS: Prostate movements can be automatically detected in a phantom using low-energy photons within 30 s after image acquisition and with a precision of better than 1 mm in translation and 1 degree in rotation (indistinguishable from the uncertainty in measuring precision). CONCLUSION: The studies show that on-line repositioning of the patient based on localization of the markers at the time of treatment is feasible, and may reduce the uncertainty in prostate location when combined with practical on-line repositioning techniques.     

A CAD-oriented method to analyze and design radiating structures based on bodies of revolution by using finite elements and generalized scattering matrix

In this work, an efficient analysis of radiating structures based on bodies of revolution is dealt with. The procedure is a hybrid method based on a segmentation of the structure into two-dimensional regions, finite elements and a spherical computation domain surrounding the antenna, defining a boundary or port where a spherical mode expansion of the fields is used. A reduced order model is computed for a fast frequency sweep. To validate this method, some structures based on bodies of revolution as a rod dielectric antenna, conical dielectric-loaded horns, profiled horns and a monopole-dielectric resonator antenna are studied and results are compared with those demonstrated by other authors. The design of a smooth-walled horn by means of the optimization of the profile is also carried out.