Effect of biotin and galactose functionalized gelatin nanofiber membrane on HEp-2 cell attachment and cytotoxicity.

In the present study, we prepared a gelatin nanofiber matrix using an electrospinning technique and cross-linked the nanofibers with 10 % glutaraldehyde vapors. The insoluble nanofibers were functionalized with bioactive molecules like biotin (1 %) and galactose (1 %) by adsorption and coelectrospinning. Surface morphology and fiber dimension were analyzed using atomic force microscopy. The amounts of biotin and galactose bound to the nanofibers before and after adsorption were quantified using high-performance liquid chromatography. Human larynx carcinoma (HEp-2) cell attachment, morphology and cytotoxic characteristics were studied using crystal violet staining and the MTT assay. Cell attachment and viability were highest in biotin- and galactose-embedded nanofibers compared to native nanofibers. Cytotoxicity was less with biotin- and galactose-embedded and adsorbed nanofibers compared to control nanofibers. Hence, we suggest that these biocompatible, nontoxic, biodegradable, functionalized nanofibers could be a potential candidate for application in tissue engineering and scaffold preparation.

Characterization and lytic activity of Pseudomonas fluorescens phages from sewage.

Pseudomonas fluorescens phages from sewage were tested against P. fluorescens isolates of soil and sewage. The phages were characterized as to host range, morphology, structural proteins and genome fingerprint. Of the seven phages isolated, one was found to be abundant in sewage (5.9×10(7) pfu/mL), having broad host range, and distinct protein and DNA profile when compared to the other six phages. DNA restriction and protein profiles of the phages and their morphology indicate the diversity in the sewage environment. None of the isolates from the rhizosphere regions of various cultivated soils were susceptible to phages isolated from sewage.

Optimization of the configuration of porous bone scaffolds made of Polyamide/Hydroxyapatite composites using Selective Laser Sintering for tissue engineering applications.

Numerous biomaterials are used to fabricate bone scaffolds to repair the bones subjected to trauma. The scaffolds are fabricated with interconnected pores with 40-70% porosity to facilitate the entry of the cells that ensures rapid bone formation. In addition, the interconnected pores also serve as a channel for the exchange of nutrients and waste materials. Rapid prototyping techniques use the CAD model of the scaffold to be fabricated which facilitates fabrication of components with complex architecture easily. This research deals with the design, fabrication and analysis of porous scaffold models with different configurations. Apart from the conventional pore geometry like cubical, spherical shaped pores, their shifted arrangements were also considered for this study. The minimum pore size used for the study is 400 µm and the porosity ranges from 40-70%. Based on the results of finite element analysis, the best scaffold configuration is identified and was fabricated with different build orientation using Selective Laser Sintering (SLS) process with different mix of Polyamide and Hydroxyapatite. The fabricated test specimens were evaluated based on mechanical tests for its strength and in vitro studies with human osteosarcoma cell line for cell growth studies. The mechanical tests witnesses good physical properties than the earlier reported research. The suitability of the porous scaffolds for bone repair is also ensured using finite element analysis of a human femur bone under various physical activities.

Cryptosporidium in AIDS patients in south India: a laboratory investigation.

Faecal samples from 108 AIDS patients submitted for parasitological examination were screened for Cryptosporidium oocysts. Twenty-four were symptomatic patients (Group I), 40 mildly symptomatic (Group II) and 47 asymptomatic (Group III). Cryptosporidium was present in faecal samples of four out of twelve diarrhoeic AIDS patients. None in other groups were positive for Cryptosporidium. Concentration of faeces may not be necessary for the oocyst detection. The study highlights the occurrence of Cryptosporidium in AIDs patients of South India.

PIP: Cryptosporidium has been associated with prolonged, life-threatening diarrhea in patients with AIDS. In this study, fecal samples from 108 AIDS patients from Chennai, India, were screened for Cryptosporidium oocysts. 21 of these patients had diarrhea at the time of screening, 40 had intermittent diarrhea, and 47 had been asymptomatic in the last month. Enteric parasites were present in 8 (43%) symptomatic patients, 26 (65%) mildly symptomatic patients, and 24 (51%) symptomatic patients. Cryptosporidium was present only among 4 patients from the group with chronic diarrhea and severe dehydration at the time of screening. These findings suggest that parasitological examination of feces may not be necessary for oocyst detection in AIDS patients with diarrhea.

Cryptosporidium parvum--propagation of oocyst in neonatal calves.

Shedding of Cryptosporidium parvum oocyst was studied in experimentally infected Jersey-Sindhi cross bred calves. Three 7 day old bull calves housed in isolation were orally infected with 10(8) oocysts of Cryptosporidium parvum. The prepatent and patent period of the experimental infection were 5 and 4 days respectively. Maximum oocyst output [2 x 10(5) oocyst per gram (OPG) was observed on the 7th day post inoculation (PI). The mean total oocyst output was 2.5 x 10(7). Diarrhoea started on the second day of oocyst shedding.

Assessment of pheromone response in biofilm forming clinical isolates of high level gentamicin resistant Enterococcus faecalis.

Twenty five clinical isolates of high level gentamicin resistant Enterococcus faecalis were tested for their biofilm formation and pheromone responsiveness. The biofilm assay was carried out using microtiter plate method. Two isolates out of the 25 (8%) were high biofilm formers and 19 (76%) and four (16%) isolates were moderate and weak biofilm formers respectively. All the isolates responded to pheromones of E. faecalis FA2-2 strain. On addition of pheromone producing E. faecalis FA2-2 strain to these isolates, seven of 19 (37%) moderate biofilm formers developed into high biofilm formers. Similarly one of the 4 (25%) weak biofilm formers developed into high level biofilm former. Twelve (48%) of the 25 isolates were transconjugated by cross streak method using gentamicin as selective marker. This proves that the genetic factor for gentamicin resistance is present in the pheromone responsive plasmid. Among these twelve transaconjugants, seven isolates and one isolate were high biofilm formers on addition of E. faecalis FA2-2 and prior to its addition respectively. Out of the total 25 isolates, eight transconjugants for gentamicin resistance could turn to high biofilm formers on addition of the pheromone producing strain. All the isolates were resistant to more than two antibiotics tested. All the isolates were sensitive to vancomycin. The results indicate the significance of this nosocomial pathogen in biofilm formation and the role of pheromone responding clinical isolates of E. faecalis in spread of multidrug resistance genes.

Characterization and lytic activity of Pseudomonas fluorescens phages from sewage

Pseudomonas fluorescens phages from sewage were tested against P. fluorescens isolates of soil and sewage. The phages were characterized as to host range, morphology, structural proteins and genome fingerprint. Of the seven phages isolated, one was found to be abundant in sewage (5.9×10(7) pfu/mL), having broad host range, and distinct protein and DNA profile when compared to the other six phages. DNA restriction and protein profiles of the phages and their morphology indicate the diversity in the sewage environment. None of the isolates from the rhizosphere regions of various cultivated soils were susceptible to phages isolated from sewage.

Rotavirus infection among infants and young children in Chennai, South India.

BACKGROUND: Group A rotavirus has been recognized as the major etiologic agent of childhood gastroenteritis in infants and young children worldwide. Rapid progress towards the development of an efficacious rotavirus vaccine has warranted extensive epidemiological studies on rotavirus serotypes that cause severe disease in developing and developed countries and to monitor the emergence of newer and unusual strains in different geographical settings that could represent variants not covered by existing vaccines. METHODS: In this study, we determined the prevalence of rotavirus infection and characterised group A rotavirus in stool samples by using monoclonal antibody (MAb) based ELISA and polyacrylamide gel electrophoresis (PAGE). Stool samples were collected from 745 children of 0-3 years of age presenting to the hospital with acute diarrhea between March 1995 and August 1999. These were assayed for antigenic (group, subgroup, serotype) and genomic (viral RNA profile and VP7 and VP4 genotype) characterization by ELISA and PAGE. RESULTS: Out of 745 stool samples analysed 168 were found to be positive for rotavirus. Among these 118 could be assigned a subgroup (SG), serotype and electropherotype (E-type). The study has evidenced the predominant occurrence of strains with short E-type, SGI and serotype G2 in 66.1% of the samples. The presence of strains representing 10 different E-types and mixed genotype specificities with G2 P[4,8] and G1-G2 P[4,8] has documented the prevailing high genomic diversity of rotaviruses in this geographical area. CONCLUSION: This study has described the predominant strains of rotavirus in south India. There is a need for further detailed studies on the molecular characterization of rotaviruses which would have important implications in vaccine evaluation programmes.