An investigation on plasma progesterone levels during pregnancy and at parturition in the Ivesi sheep

We have investigated the toxicity of dose-escalation of BCNU, etoposide and melphalan ('BEM') chemotherapy with autologous stem cell transplantation in patients with haematological malignancies. Seventy-two patients with haematological malignancies were treated with BCNU (600 mg/m2, 450 mg/m2 or 300 mg/m2), etoposide 2 g/m2 and melphalan 140 mg/m2 followed by autologous bone marrow transplantation (ABMT), n = 51, or autologous peripheral blood progenitor cell transplantation (APBPCT), n = 21. Liver and pulmonary function was monitored pretransplant and at regular intervals post-transplant. Mucositis was graded daily during in-patient stay. There was a significantly higher incidence of symptomatic pulmonary toxicity in the patients who received BCNU at 600 mg/m2 than in the other two groups, and there was a significant increase in the incidence of asymptomatic decrease in carbon monoxide (KCO) in the patients who received BCNU 450 mg/m2. There was no significant difference between the three groups in the incidence and severity of mucositis or in the incidence of transiently abnormal liver function. We conclude that etoposide at 2 g/m2 can be used without unacceptable mucositis. BCNU at 600 mg/m2 is associated with an unacceptably high incidence of lung toxicity, but at 450 mg/m2 there is minimal symptomatic lung toxicity.     

Evolution of glomerular basement membrane changes in chronic rejection

We have investigated the evolution of chronic glomerular changes in the absence of the recurrence of original disease in an experimental rat model of chronic renal allograft rejection. Using serial graft needle biopsies and serum creatinine levels, we were able to focus on early glomerular changes that are associated with good graft function. The recipient rats were divided into 5 groups, 2 with allogeneic (DA to WF) transplants and 3 with syngeneic (DA to DA) transplants. In the first 2 allogeneic groups, one group received cyclosporine (CsA) for 2 weeks (n = 7) and the other received CsA for 12 weeks (n = 5). In the 2-week treatment group, all allografts developed chronic rejection, compared with none in the 12-week group. Syngeneic controls received CsA for 2 (n = 3) and 12 weeks (n = 3), or no immunosuppression (n = 2) in order to exclude the effects of CsA. The first detectable ultrastructural event was slight deposition of electron lucent material in the glomerular basement membrane. Contrary to previous morphological studies, the initial deposition was not subendothelial, but was within the lamina densa itself. Examination of allogeneic grafts with good graft function and syngeneic grafts showed glomerular alterations that were similar to the early changes preceding chronic rejection. The intensity of changes in optimally immunosuppressed allografts was mild, and they were arrested early in the evolving stage of glomerular basement membrane changes. In the suboptimally immunosuppressed allografts with chronic rejection, the glomerular basement membrane changes became more pronounced and extensive in subsequent biopsies. Thus, all recipients in different groups showed similar glomerular alterations, but to different intensities. These results suggest a common pathogenetic mechanism which might be endothelial damage. In chronic rejection, the endothelial damage might be immunologically mediated by rejection episodes and progressive, whereas in syngeneic grafts and in allografts without chronic rejection, perioperative trauma, ischemia, and graft reperfusion may be responsible for the self-limiting glomerular changes.     

Corrosion behavior of carbon steel rock bolt in simulated Yucca Mountain ground waters

Medium carbon steel (AISI 1040) was one of the candidate materials for rock bolts to reinforce the borehole liners and emplacement drifts of the high-level nuclear waste repository in Yucca Mountain. The corrosion performance of this structural steel was investigated by techniques such as linear polarization, electrochemical impedance spectroscopy (EIS), and laboratory immersion tests in simulated ground waters. The corrosion rates of the steel were measured for the temperatures in the range from 25 °C to 85 °C, for the ionic concentrations of 1 time (1×), 10 times (10×), and a hundred times (100×) ground water concentration. The steel corroded uniformly at penetration rates of 35 to 200 μm/year in the deaerated waters, and at 200 to 1000 μm/year in the aerated waters. Increasing temperatures in the deaerated waters increased the corrosion rate of the steel. However, increasing ionic concentrations influenced the corrosion rate only slightly. In the aerated 1×and 10×waters, increasing temperatures increased the rates of the steel significantly. In the aerated 100×waters, the corrosion rate increased from 25 °C to 45 °C and decreased at higher temperatures (65 °C and up) due to the formation of oxide/hydroxide films and salt scales on the surface of the steel specimen. The steel suffered pitting corrosion in the both deaerated and aerated hot ground water environments after anodic polarization. This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the. TMS Corrosion and Environmental Effects and Nuclear Materials Committees.     

Effect of Lateral Water Surface Profile on Side Weir Discharge

The average water surface slope in the lateral direction is taken into account as a local parameter ψ to study flow over a side weir. It was later shown that for smaller side weir lengths and side weir portions with no entrance and exit transition effects, ψ can be obtained from a numerical integral and also from the measurements of water surface elevations in the lateral direction. The effect of elemental weir length was further determined. Dividing the weir length into smaller computational segments has the effect of lowering the water surface to approach the measured profile, the downstream ends being coincident. The model was verified using experimental data.     

How to diagnose chronic rejection. A study in porcine intestinal allografts

The conventional Spin-Echo sequences have been the most used acquisition techniques on Magnetic Resonance Imaging (MRI) of the brain, since the beginning of 1990s. Recently, however, technological developments proposed such new fast acquisition techniques, with a dramatic reduction in acquisition time as Gradient Echo, Turbo Spin Echo, Gradient Spin Echo ed Echo Planar sequences. We investigated the comparative adequacy of the new fast sequences, in brain MR studies versus conventional sequences, on medium field strength MR equipment (.5 T). On in vitro exams S/N ratio was evaluated and on in vivo study C/N ratio between white substance grey substance and fluid were evaluated, in 15 healthy volunteers. All the exams were carried out on Philips NT5 Gyroscan MR unit operating at .5 T, with 15 mT/m power gradients. Both conventional and fast sequences Spin-Echo (SE), Inversion Recovery (IR), Gradient-Echo (GE), Turbo Spin-Echo (TSE), Gradient Spin-Echo (GRASE) and Echo Planar (EPI), all optimized to obtain T1, T2 and T1-IR weighted images, were performed. The sequences were evaluated separately comparing different acquisition techniques relative to the same type of contrast (T1, T2, and T1-IR). The results indicate the superiority of the fast acquisition techniques, both in terms of quality and acquisition times, except for T1-weighted images, where the conventional Spin-Echo sequences confirmed to be superior. In conclusion, the present study suggests that fast acquisition techniques can improve the conventional protocol of sequences, in the anatomical representation of the normal brain even with medium field strength equipment only on T2 and T1-IR weighted images. On T1-weighted imaging conventional SE acquisition technique is still the best choice. The time saving obtained with fast sequences can therefore be used for an overall improvement in the quality of images, and to apply accessory acquisition plans on routine exams.     

Determination of exchange enthalpy and entropy parameters of poly(dimethyl siloxane) with some n-alkanes by inverse gas chromatography

The total interaction parameter at infinitely high polymer concentration. χ_t^∞, and the effective exchange energy parameter, X̄₁₂, of poly(dimethyl siloxane) with n-pentane, n-hexane, n-heptane and n-nonane were determined around room temperature using the inverse gas chromatography technique. The values of χ_t^∞ are in agreement with corresponding literature values. The exchange enthalpy X₁₂ and entropy, Q₁₂, parameters were determined at the same temperature. The X₁₂ parameters increase with the carbon number of the n-alkanes, while their temperature dependence is almost negligible. The Q₁₂ parameters are approximately independent of temperature and carbon number of the n-alkanes.     

Relative brittleness characterization of some selected granitic building stones: Influence of mineral grain size

Being crystalline materials, brittleness may be an important issue for granitic rocks, especially when they are subject to certain loading conditions. Therefore, in practice, more specifically in their usage as a natural building stone, there is a need for their brittleness characterization. This paper reports a study carried out on some selected granitic rock types in order to determine their relative brittleness index values and relate it to their mineral grain size. For this purpose, three different types of granitic rocks similar in mineral composition, but diverse in grain sizes were selected for the execution of the study. The relative brittleness index values of the studied rock types were determined from the size effect method by using the point load test apparatus. Based on the results of this investigation it is was concluded that, rather than the proportions of the rock forming minerals such as quartz and feldspars, the grain size of feldspars could be the dominant parameter affecting relative brittleness values of the tested rocks.     

Effect of single and multi-channel electrodes application on EDM fast hole drilling performance

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. A sleeve spring damper is one such measure to reduce the torsional vibration. In this study, the closed form equations to predict the spring constant of a sleeve spring and the dynamic characteristics of the torsional vibration damper are proposed to calculate stiffness of the damper, and verified their availability through the finite element analysis. Our theoretical values are in good agreement with results obtained from finite element analysis and experiments. Results obtained from the derived equation enable designers to be more efficient.