Modified chitosan hydrogels as drug delivery and tissue engineering systems: present status and applications

AbstractChitosan, a natural cationic polysaccharide, is prepared industrially by the hydrolysis of the aminoacetyl groups of chitin, a naturally available marine polymer. Chitosan is a non-toxic, biocompatible and biodegradable polymer and has attracted considerable interest in a wide range of biomedical and pharmaceutical applications including drug delivery, cosmetics, and tissue engineering. The primary hydroxyl and amine groups located on the backbone of chitosan are responsible for the reactivity of the polymer and also act as sites for chemical modification. However, chitosan has certain limitations for use in controlled drug delivery and tissue engineering. These limitations can be overcome by chemical modification. Thus, modified chitosan hydrogels have gained importance in current research on drug delivery and tissue engineering systems. This paper reviews the general properties of chitosan, various methods of modification, and applications of modified chitosan hydrogels

Maternal and Fetal Outcome in Elective versus Emergency Cesarean Section

Introduction: The complications of cesarean section are seen more commonly in emergency than in elective cases. The aim of this study was to find out the incidence of cesarean section in Nepal Medical College Teaching Hospital and to compare the maternal and fetal outcome in elective and emergency cesarean section. 
 Methods: A prospective study of all the cases undergoing cesarean section in Nepal Medical College Teaching Hospital was carried out during the period of six months from Asar 2069 to Mangsir 2069. 
 Results: The incidence of cesarean section was 254 (22.30%) out of which emergency cesarean section accounted for 167 (65.7%) and elective cesarean section for 87 (34.3%). The usual indications of emergency cesarean section were fetal distress, previous cesarean section in labour, non progress of labour and prolonged second stage of labour. The usual indications of elective cesarean section were previous cesarean section, breech, cephalopelvic disproportion and cesarean section on demand. There was found to be no significant difference in age, period of gestation, blood loss and blood transfusion in emergency vs. elective cesarean section. There was significant difference seen in the length of hospital stay, fever, urinary tract infection, wound infection and low APGAR in five minutes indicating that these were more common in emergency cesarean section. Significant difference was also seen in the incidence of postpartum haemorrhage indicating that it was seen more in elective cesarean section. 
 Conclusions: The incidence of cesarean section in Nepal Medical College Teaching Hospital is high and the overall complication rate is higher in emergency cesarean section than in elective cesarean section. Keywords: cesarean section; fetal and maternal outcome

MEDIATOR SUBUNIT17 is required for transcriptional optimization of root system architecture in Arabidopsis

Mediator subunit MED17 regulates root system architecture by establishing a link between auxin and sucrose signaling pathways. Sucrose and auxin are well-known determinants of root system architecture (RSA). However, the factors that connect the signaling pathways evoked by these two critical factors during root development are poorly understood. In this study, we report the role of MEDIATOR SUBUNIT17 (MED17) in RSA and its involvement in the transcriptional integration of sugar and auxin signaling pathways in Arabidopsis (Arabidopsis thaliana). Sucrose regulates root meristem activation through the TARGET OF RAPAMYCIN-E2 PROMOTER BINDING FACTOR A (TOR-E2FA) pathway, and auxin regulates lateral root (LR) development through AUXIN RESPONSE FACTOR-LATERAL ORGAN BOUNDARIES DOMAIN (ARF-LBDs). Both sucrose and auxin play a vital role during primary and LR development. However, there is no clarity on how sucrose is involved in the ARF-dependent regulation of auxin-responsive genes. This study establishes MED17 as a nodal point to connect sucrose and auxin signaling. Transcription of MED17 was induced by sucrose in an E2FA/B-dependent manner. Moreover, E2FA/B interacted with MED17, which can aid in the recruitment of the Mediator complex on the target promoters. Interestingly, E2FA/B and MED17 also occupied the promoter of ARF7, but not ARF19, leading to ARF7 expression, which then activates auxin signaling and thus initiates LR development. MED17 also activated cell division in the root meristem by occupying the promoters of cell-cycle genes, thus regulating their transcription. Thus, MED17 plays an important role in relaying the transcriptional signal from sucrose to auxin-responsive and cell-cycle genes to regulate primary and lateral root development, highlighting the role of the Mediator as the transcriptional processor for optimal root system architecture in Arabidopsis

Biodegradation of reactive orange 16 (RO-16) dye in packed bed bioreactor using seeds of Ashoka and Casuarina as packing medium

216-221The main objective of this work was to evaluate the performance of Ashoka and Casuarina (abundantly available in India as agrowaste) seeds as packing material with immobilized mixed culture of microorganisms for biodegradation of reactive orange dye (RO-16) in the continuous packed bed bioreactor. The percent removal of RO-16 was increased with time in both cases and attained constant value on the 10th d of operation with maximum removal 63.5±5% and 69.27±5%, respectively for Ashoka and Casuarina seeds, at inlet flow rate of 1.0 LPH and initial concentration of 500 ppm. The second order of kinetics applied and it fitted well for both packing materials. The results demonstrate that the selected seeds have potential as to be used as packing material for biodegradation application in bioreactors