Experimental study and kinetic modeling of methanol conversion to propylene with co-feeding of C4 and C5/C6 hydrocarbon cuts over a ZSM-5 catalyst.

Extensive experimental data were used to develop a comprehensive kinetic model for the methanol to propylene (MTP) process over a ZSM-5 catalyst. Preliminary experiments were performed to determine the reaction conditions that would ensure the absence of external (film) and internal mass transfer resistances. The kinetic experiments were subsequently carried out at 420-500 °C under conditions where mass transfer limitations were absent. A detailed reaction network was proposed for the MTP process based on the experimental product distribution and various reported kinetic models in the literature. According to the first series of experiments (without C4 and C5/C6 recycle streams) conducted at various temperatures, the best yield for propylene production was achieved at 480 °C with a water to methanol ratio of 0.7. Subsequently, kinetic experiments were performed at 480 °C and a water to methanol ratio of 0.7 using feeds with different amounts of C4 and C5/C6 hydrocarbons as recycle streams. Species material balances for the integral tubular reactor along with power-law rate functions and the Arrhenius equation for rate constants were employed in an optimization algorithm to obtain the kinetic parameters. The predictive ability of the model was checked against experimental data, and the kinetic parameters were validated by additional experiments.

Post-dural puncture headache following lumbar spinal drain: an atypical presentation with cognitive symptoms.

Post-dural puncture headache is a consequence of cerebrospinal fluid loss, leading to reduced intracranial pressure. Its classical symptoms include a frontal-occipital headache which is worse on standing, neck stiffness, nausea, hearing loss and photophobia. In this report, we describe an atypical presentation of post-dural puncture headache in a 72-year-old woman following an endovascular repair of an aortic aneurysm, before which a lumbar spinal drain was placed to reduce the risk of spinal cord ischemia. Following drain removal, the patient developed hypoactive delirium, challenges with both depth perception and fine motor skills and a mild headache. An epidural blood patch was performed, which resulted in the complete resolution of her symptoms. This case highlights an atypical presentation of post-dural puncture headache in an older patient, in whom the major symptoms were cognitive. Cerebrospinal fluid leakage should be considered as a cause of postoperative delirium in patients who have undergone neuraxial anaesthesia.

FKRP-dependent glycosylation of fibronectin regulates muscle pathology in muscular dystrophy.

The muscular dystrophies encompass a broad range of pathologies with varied clinical outcomes. In the case of patients carrying defects in fukutin-related protein (FKRP), these diverse pathologies arise from mutations within the same gene. This is surprising as FKRP is a glycosyltransferase, whose only identified function is to transfer ribitol-5-phosphate to α-dystroglycan (α-DG). Although this modification is critical for extracellular matrix attachment, α-DG's glycosylation status relates poorly to disease severity, suggesting the existence of unidentified FKRP targets. Here we reveal that FKRP directs sialylation of fibronectin, a process essential for collagen recruitment to the muscle basement membrane. Thus, our results reveal that FKRP simultaneously regulates the two major muscle-ECM linkages essential for fibre survival, and establishes a new disease axis for the muscular dystrophies.

An improved reprogrammable mouse model harbouring the reverse tetracycline-controlled transcriptional transactivator 3.

Reprogrammable mouse models engineered to conditionally express Oct-4, Klf-4, Sox-2 and c-Myc (OKSM) have been instrumental in dissecting molecular events underpinning the generation of induced pluripotent stem cells. However, until now these models have been reported in the context of the m2 reverse tetracycline-controlled transactivator, which results in low reprogramming efficiency and consequently limits the number of reprogramming intermediates that can be isolated for downstream profiling. Here, we describe an improved OKSM mouse model in the context of the reverse tetracycline-controlled transactivator 3 with enhanced reprogramming efficiency (>9-fold) and increased numbers of reprogramming intermediate cells albeit with similar kinetics, which we believe will facilitate mechanistic studies of the reprogramming process.

Cadmium chloride exhibits a profound toxic effect on bacterial microflora of the mice gastrointestinal tract.

Cadmium (Cd²(+)), a naturally occurring heavy metal, is an important environmental pollutant and a potent toxicant to bacteria. The gastrointestinal (GI) tract microflora has a marked capacity to cope with the increased load of ingested metals. However, heavy metals may have harmful effects on GIT microflora. Under the conditions of experimental exposure to cadmium, changes in the population of intestinal microflora in healthy mice were examined. Five experimental groups received 23 to 50 mg kg⁻¹ cadmium in drinking water and control group was given water free from cadmium for 45 days. Intestinal contents and biopsy samples were aseptically collected and bacterial counts were performed. The microflora of the intestine in control group was represented by bacteria of the genera Bacillus cereus, Lactobacillus spp., Clostridium spp., Escherichia coli, Klebsiella spp., Pseudomonas spp., Enterococcus spp. and Proteus spp. As the result of dysbiosis induced by the introduction of cadmium, a sharp decrease in the population of all microbial species in the intestine was observed. The deleterious effect of cadmium appeared to be less in the large intestine and rectum than that of small intestine, suggesting a site-specific influence of cadmium. The gram-negative bacteria tested were less sensitive to cadmium compared to the gram-positive bacteria because of their possible different ability to uptake the metal ions.

Isolation and biochemical characterization of the iC3b receptor of Candida albicans.

In an effort to identify the protein structure on Candida albicans, pseudohyphal forms which had been shown earlier to bind human iC3b, a protein of about 42 kDa (p42), were obtained from lysates of pseudohyphal forms by absorption with C3(H2O)-Sepharose. An antiserum raised in rabbits against this protein effectively inhibited adherence of sheep erythrocytes carrying iC3b (EAC3bi) to pseudohyphal forms. p42 cross-reacted with OKM-1, a monoclonal antibody directed against the human complement receptor type 3 (CR3, CD11b). This protein, p42, was designated p42-CR3. The antiserum against p42-CR3 was used for further purification of lysates by affinity chromatography. Three proteins of 66, 55, and 42 kDa were isolated. All were recognized by OKM-1 in immunoblots (p66-, p55-, and p42-CR3). The different proteins were separated and treated with neuraminidase and endoglycosidase F. Almost complete deglycosylation of the p66-CR3 protein was obtained after treatment with neuraminidase, indicating a high degree of glycosylation. Neuraminidase also had an effect on p55-CR3, but not on p42-CR3. Endoglycosidase F did not alter any of the three proteins. In ligand blots, p42-CR3 bound C3(H2O), C3b, and iC3b but not C3d; p55-CR3 clearly reacted with C3(H2O) and weakly reacted with C3b and iC3b. p66-CR3 never showed reactivity. It is suggested that p55 and p66 represent glycosylated forms of p42-CR3. Although C. albicans CR3 and human CR3 cross-react and bind identical ligands, the two receptors differ in structure.