Statistical Methods for Modeling the Compressive Strength of Geopolymer Mortar.

In recent years, geopolymer has been developed as an alternative to Portland cement (PC) because of the significant carbon dioxide emissions produced by the cement manufacturing industry. A wide range of source binder materials has been used to prepare geopolymers; however, fly ash (FA) is the most used binder material for creating geopolymer concrete due to its low cost, wide availability, and increased potential for geopolymer preparation. In this paper, 247 experimental datasets were obtained from the literature to develop multiscale models to predict fly-ash-based geopolymer mortar compressive strength (CS). In the modeling process, thirteen different input model parameters were considered to estimate the CS of fly-ash-based geopolymer mortar. The collected data contained various mix proportions and different curing ages (1 to 28 days), as well as different curing temperatures. The CS of all types of cementitious composites, including geopolymer mortars, is one of the most important properties; thus, developing a credible model for forecasting CS has become a priority. Therefore, in this study, three different models, namely, linear regression (LR), multinominal logistic regression (MLR), and nonlinear regression (NLR) were developed to predict the CS of geopolymer mortar. The proposed models were then evaluated using different statistical assessments, including the coefficient of determination (R2), root mean squared error (RMSE), scatter index (SI), objective function value (OBJ), and mean absolute error (MAE). It was found that the NLR model performed better than the LR and MLR models. For the NLR model, R2, RMSE, SI, and OBJ were 0.933, 4.294 MPa, 0.138, 4.209, respectively. The SI value of NLR was 44 and 41% lower than the LR and MLR models' SI values, respectively. From the sensitivity analysis result, the most effective parameters for predicting CS of geopolymer mortar were the SiO2 percentage of the FA and the alkaline liquid-to-binder ratio of the mixture.

Recurrent, sequential, bilateral deep cerebellar hemorrhages: a case report.

INTRODUCTION: Hypertensive intra-cerebral hemorrhage is usually a one-time event and recurrences are rare. Most recurrences develop as part of long-term failure of blood pressure control. The site of the re-bleed is usually limited to the basal ganglia and thalami. CASE PRESENTATION: We report the case of a 59-year-old hypertensive Caucasian woman who developed two sequential, right- and then left-sided, deep cerebellar hemorrhages. The second hemorrhage followed the first one by 57 days, at a time when her blood pressure was optimally controlled. In spite of these critical sites and short duration between the two bleeds, the patient achieved a relatively good functional recovery. Her brain magnetic resonance angiogram was unremarkable. CONCLUSION: The development of recurrent hypertensive hemorrhage is rare and usually occurs within two years of the first bleed. To the best of our knowledge, this is the first reported case of bilateral, sequential, right- and then left-sided deep cerebellar hemorrhages. These hemorrhages were separated by eight weeks and the patient had a relatively good functional recovery. We believe that hypertension was the etiology behind these hemorrhages.

Multiple ulcers in the small and large intestines occurred during tocilizumab therapy for rheumatoid arthritis.

Tocilizumab is a monoclonal antibody against human interleukin-6 receptor which blocks the binding of interleukin-6 to its receptor. Tocilizumab is effective for the treatment of inflammatory disorders including rheumatoid arthritis. We report a case of multiple ulcers in the small and large intestines, which occurred during tocilizumab therapy. A 57-year-old woman started to use tocilizumab for rheumatoid arthritis. Three months later, she complained of hematochezia. Double-balloon endoscopy revealed multiple small aphthoid ulcers in the small and large intestines. One month after the woman had recovered, she was given tocilizumab again. The woman had hematochezia and abdominal pain again 2 weeks later. Colonoscopy revealed multiple round, discrete punched-out ulcers in the terminal ileum, and vast deep ulcers from the cecum to the descending colon. Bioptic histopathology and cultivation showed non-specific findings. Six weeks after discontinuation of tocilizumab, ulcers in the small and large intestine dramatically improved, leaving ulcer scars. This disease course and the results of examination made us strongly suspect that tocilizumab induced multiple ulcers in the small and large intestines. Interleukin-6 is a pleiotropic cytokine and involved in intestinal mucosal wound healing as well as in inflammatory processes. It is possible that tocilizumab inhibited tissue repair of the intestine and caused intestinal ulcers.

Masa en mediastino anterior / Anterior mediastinal mass

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Conformational requirements of collagenous peptides for recognition by the chaperone protein HSP47.

The collagen binding chaperone HSP47 interacts with procollagen in the endoplasmic reticulum and plays a crucial role in the biosynthesis of collagen. We recently demonstrated that typical collagen model peptides, (Pro-Pro-Gly)(n), possess sufficient structural information for interaction with HSP47 (Koide, T., Asada, S., and Nagata, K. (1999) J. Biol. Chem. 274, 34523-34526). Here we show that binding of (Gly-Pro-Pro)(n) peptides to HSP47 can be detected using the two-hybrid system in yeast if a trimerizing domain is fused to the C termini of the peptides. Some peptides interacted with HSP47 at a lowered assay temperature at 24 degrees C but not at 30 degrees C, indicating the importance of conformational change of the substrate peptides. To analyze the spectrum of HSP47 substrate sequences, we performed two-hybrid screening of collagen-like peptides in designed random peptide libraries using HSP47 as a bait. In selected peptides, the enrichment ratio calculated for each amino acid residue correlated strongly with the contribution of the residue to triple-helix stability independently determined using synthetic collagen model peptides. Taken together, our results suggest that HSP47 preferentially recognizes collagenous Gly-X-Y repeats in triple-helical conformation. We also demonstrated that screening of combinatorial peptide libraries is a powerful strategy to determine conformational requirements as well as the elucidation of binding motifs in primary structure.

Alterations of skin glycosaminoglycans in patients with ALS.

BACKGROUND AND OBJECTIVE: Collagen abnormalities of skin have been reported among patients with ALS. However, little is known concerning glycosaminoglycans of the skin in ALS. Our objective was to clarify morphologic and biochemical findings of skin glycosaminoglycans among patients with ALS. METHODS: We performed morphologic studies and biochemical analysis of glycosaminoglycans of skin from 8 patients with ALS, 6 patients with other neurologic or muscular diseases (control group A), and 7 patients without neurologic disorders (control group B). RESULTS: The wide spaces that separate collagen bundles reacted strongly with Alcian blue stain in skin from patients with ALS and stained more markedly as ALS progressed. Staining with Alcian blue was virtually eliminated by Streptomyces hyaluronidase. The content of hyaluronic acid was significantly higher (p < 0.001) among patients with ALS than in control groups A and B. There was a significant positive correlation between content of hyaluronic acid and duration of illness among patients with ALS (r = 0.88, p < 0.01). However, there was no significant difference in content of dermatan sulfate, chondroitin sulfate-4S, or chondroitin sulfate-6S between patients with ALS and control groups A and B. There was also an appreciable positive correlation between optical density of Alcian blue and content of hyaluronic acid among patients with ALS (r = 0.92, p < 0.01). CONCLUSIONS: The data suggest that a metabolic alteration of glycosaminoglycans related to the increased amount of hyaluronic acid may take place in the skin of patients with ALS.