Rotavirus infection among Sudanese children younger than 5 years of age: A cross sectional hospital-based study

Introduction: In Sudan, rotavirus has been one of the important causative agents of diarrhea among children. Rotavirus A is well known as the leading cause of diarrhea in young children worldwide. It was estimated to  account for 41% of hospitalized cases of acute gastroenteritis among children in Sub-Saharan Africa. This study aimed to determine the  prevalence and the common clinical presentations of rotavirus A infection among Sudanese children with gastroenteritis seeking management in hospitals.Methods: 755 Sudanese children less than 5 years of age suffering from acute gastroenteritis in hospital settings were included. The positive stool specimens for rotavirus A was used for extract Ribonucleic acid (RNA) and the RNA product was loaded on formaldehyde agarose gel and visualized under UV illumination.Results: Of the 755 children, 430(57%) were males while 325(43%) were female. The age of children ranged from 1 to 60  months. There were 631 (84%) children who were less than 24 months of age. Out of the 755 stool samples, 121(16%) were positive for rotavirus. Of the 121 infected children with rotavirus, 79(65.3%) were male and  42(34.7%) were female and the highest infection rate was seen among 91(75.2%) of children up to 12 months of age. Children of illiterate parents were more infected with rotavirus than children of educated  parents. Severe dehydration present among 70% of infected children with rotavirus. Conclusion: Since this study is hospital-bas Conclusion:ed, the 16%  prevalence rate may not reflect the true prevalence among Sudanese children, thus a community-based surveillance is needed

Exploring factors affecting undergraduate medical students’ study strategies in the clinical years: a qualitative study

The aim of this study is to explore the effects of clinical supervision, and assessment characteristics on the study strategies used by undergraduate medical students during their clinical rotations. We conducted a qualitative phenomenological study at King Saud Bin Abdulaziz University for Health Sciences, College of Medicine, Riyadh, Saudi Arabia during the period from November 2007 to December 2008. We conducted semi-structured focus groups interviews with students and conducted individual interviews with teachers and students to explore students’ and clinical teachers’ perceptions and interpretations of factors influencing students’ study strategies. Data collection was continued until saturation was reached. We used Atlas-ti Computer Software (Version 5.2) to analyse the data, apply the obtained themes to the whole dataset and rearrange the data according to the themes and sub-themes. Analysis of data from interviews with twenty-eight students and thirteen clinical supervisors yielded three major themes relating to factors affecting students’ study strategies: “clinical supervisors and supervision”, “stress and anxiety” and “assessment”. The three themes we identified played a role in students’ adoption of different study strategies in the “community of clinical practice”. It appeared that teachers played a key role, particularly as assessors, clinical supervisors and as a source of stress to students

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Microfiberoptic Measurement of Extracellular Space Volume in Brain and Tumor Slices Based on Fluorescent Dye Partitioning

The fractional volume occupied by extracellular space in tissues, termed α, is an important parameter of tissue architecture that affects cellular functions and drug delivery. We report a technically simple fluorescent dye partitioning method to measure α in tissue slices based on microfiberoptic detection of dye fluorescence in tissue versus overlying solution. Microfiberoptic tip geometry and dyes were selected for α determination from fluorescence intensity ratios, without the need to correct for illumination profile, light scattering/absorption, or dye binding. The method was validated experimentally using cell-embedded gels of specified α-values and optical properties. In mouse brain slices, α was strongly location-dependent, ranging from 0.16 in thalamus to 0.22 in brainstem, and was sensitive to cell volume changes. Aquaporin-4 water channel gene deletion caused significant extracellular space expansion, with α = 0.181 ± 0.002 in cortex in wild-type mice and 0.211 ± 0.003 in Aquaporin-4 knockout mice. In slices of LLC1 cell tumors grown in mice to ∼5 mm diameter, α decreased remarkably from ∼0.45 in superficial tumor to <0.25 in deeper (>100 μm) tumor. Fluorescent dye partitioning with microfiberoptic detection permits rapid, accurate, and anisotropy-insensitive determination of α-values in tissue slices

Penetratin-Membrane Association: W48/R52/W56 Shield the Peptide from the Aqueous Phase

Using molecular dynamics simulations, we studied the mode of association of the cell-penetrating peptide penetratin with both a neutral and a charged bilayer. The results show that the initial peptide-lipid association is a fast process driven by electrostatic interactions. The homogeneous distribution of positively charged residues along the axis of the helical peptide, and especially residues K46, R53, and K57, contribute to the association of the peptide with lipids. The bilayer enhances the stability of the penetratin helix. Oriented parallel to the lipid-water interface, the subsequent insertion of the peptide through the bilayer headgroups is significantly slower. The presence of negatively charged lipids considerably enhances peptide binding. Lateral side-chain motion creates an opening for the helix into the hydrophobic core of the membrane. The peptide aromatic residues form a π-stacking cluster through W48/R52/W56 and F49/R53, protecting the peptide from the water phase. Interaction with the penetratin peptide has only limited effect on the overall membrane structure, as it affects mainly the conformation of the lipids which interact directly with the peptide. Charge matching locally increases the concentration of negatively charged lipids, lateral lipid diffusion locally decreases. Lipid disorder increases, through decreased order parameters of the lipids interacting with the penetratin side chains. Penetratin molecules at the membrane surface do not seem to aggregate