Characterizing microscale biological samples under tensile loading: stress-strain behavior of cell wall fragment of onion outer epidermis.

PREMISE OF THE STUDY: The results of published studies investigating the tissue-scale mechanical properties of plant cell walls are confounded by the unknown contributions of the middle lamella and the shape and size of each cell. However, due to their microscale size, cell walls have not yet been characterized at the wall fragment level under tensile loading. It is imperative to understand the stress-strain behavior of cell wall fragments to relate the wall's mechanical properties to its architecture. • METHODS: This study reports a novel method used to characterize wall fragments under tensile loading. Cell wall fragments from onion outer epidermal peels were cut to the desired size (15 × 5 µm) using the focused ion beam milling technique, and these fragments were manipulated onto a microelectromechanical system (MEMS) tensile testing device. The stress-strain behavior of the wall fragments both in the major and minor growth directions were characterized in vacuo. • KEY RESULTS: The measured mean modulus, fracture strength, and fracture strain in the major growth direction were 3.7 ± 0.8 GPa, 95.5 ± 24.1 MPa, and 3.0 ± 0.5%, respectively. The corresponding properties along the minor growth direction were 4.9 ± 1.2 GPa, 159 ± 48.4 MPa, and 3.8 ± 0.5%, respectively. • CONCLUSIONS: The fracture strength and fracture strain were significantly different along the major and minor growth directions, the wall fragment level modulus of elasticity anisotropy for a dehydrated cell wall was 1.23, suggesting a limited anisotropy of the cell wall itself compared with tissue-scale results.

Control of coliform bacteria detected from diarrhea associated patients by extracts of Moringa oleifera.

The aims of this study were to determine the total population of coliform bacteria in the samples collected from diarrhea associated patients from the local area of Bangladesh and to examine the antibacterial efficacy of leaf extracts of Moringa oleifera (Moringaceae) against the isolated coliform bacteria. The coliform bacteria detected in these samples by some microbial-biochemical tests such as Escherichia coli, Shigella dysenteriae, Salmonella sp., Enterobacter sp., Klebsiella pneumoniae and Serratia marcescens. The total isolation rate of coliform bacterial species was ranged from 38.01-3.51%. At the concentration of 300 ig/disc, the organic extracts of hexane, chloroform, ethyl acetate and methanol extracts of Moringa oleifera leaf exhibited a remarkable antibacterial effect against all the tested bacterial pathogens. The zones of inhibition against all the tested bacterial pathogens were found in the range of 8.0 to 23.2 mm, along with their respective minimum inhibitory concentration (MIC) values ranging from 62.5-1000 ig/mL. The results obtained in this study suggest that the extracts from Moringa oleifera leaf can be a source of natural antimicrobials with potential applications in pharmaceutical industry to control coliform bacteria.

Effect of micronutrients on morbidity and duration of hospital stay in childhood pneumonia.

A cross-sectional and controlled clinical trial was conducted in under-5 children to compare the effects of supplementation of five micronutrients (vitamin-A, vitamin C, vitamin E, folic acid and zinc) on the morbidity and on the duration of hospital stay in pneumonia. Data were collected from 1150 children. Among them 350 children were excluded for various reasons and finally data from 800 children were analyzed. Among these 800 children 59.00% (475) were male and 41.00% (325) were female. The mean+/-SD age was 6.5+/-5.6 months and 56.25% (450) were infants. The children were divided into two groups-400 in control group and 400 in intervention (case) group. In both the groups, specific treatment was given by ampicillin and gentamycin. In intervention group, five micronutrients were given in 200 children from the day of admission and continued up to discharge. Another 200 children were again divided into 5 sub-groups (40 in each sub-group) and a single micronutrient was given in the same way in each sub-groups. All the subjects were suffering clinically from severe pneumonia and radiologically from bronchopneumonia. Cases and controls were matched by parents' occupation, education level, economic status and family members. All the children were fully vaccinated as per existing EPI schedule of the country, partially breastfed up to six months and after six months weaned by carbohydrate rich diet. All the children were in mild (grade I) PEM according to Gomez's classification. Venous blood was collected for estimation of serum level of five micronutrients from all the samples before starting treatment by standard procedures. The average blood level of all the micronutrients was low. The average duration of hospital staying was 6.75 days in intervention group and 7.75 days in control group (p<0.01). Chest indrawing and fast breathing disappeared earlier in the intervention group (p<0.01) suggesting that supplementation of micronutrients decrease the morbidity and duration of hospital stay of children suffering from pneumonia.

Comparisons between invasive and noninvasive determinations of embryonic heart rate in chickens.

The embryonic heart rate (HR) of chicken eggs was determined by ballistocardiography, electrocardiography, impedance-cardiography and acoustocardiography. The effects of these different methods on the HR were examined for young (12-day-old) and late (16- and 18-day-old) embryos. Ballistocardiography is a non-invasive method. Nevertheless, the mean HRs determined using this method at 5-hr intervals were significantly different in many embryos. This difference was caused by the natural variability of embryonic HR. The statistical analyses indicated that any of these four methods did not influence the HR measurement and can be used as a simple means for determination of the embryonic HR.

Contact hemolysin production by strains of enteroaggregative Escherichia coli isolated from children with diarrhea.

Forty-five strains of enteroaggregative Escherichia coli were tested for hemolytic activity with different culture media and erythrocytes from different species. Thirty-seven strains showed proteinase K-sensitive contact hemolysin activity with sheep erythrocytes when cultured in Casamino Acids-yeast extract broth supplemented with 1 mM calcium chloride and when cultured in nutrient broth media. The production of contact hemolysin was dependent on temperature, pH, and culture conditions.