Nitric oxide-releasing polymers containing the [N(O)NO]- group

Ions of structure X[N(O)NO]- display broad-spectrum pharmacological activity that correlates with the rate and extent of their spontaneous, first-order decomposition to nitric oxide when dissolved. We report incorporation of this functional group into polymeric matrices that can be used for altering the time course of nitric oxide release and/or targeting it to tissues with which the polymers are in physical contact. Structural types prepared include those in which the [N(O)NO]- group is attached to heteroatoms in low molecular weight species that are noncovalently distributed throughout the polymeric matrix, in groupings pendant to the polymer backbone, and in the polymer backbone itself. They range in physical form from films that can be coated onto other surfaces to microspheres, gels, powders, and moldable resins. Chemiluminescence measurements confirm that polymers to which the [N(O)NO]- group is attached can serve as localized sources of nitric oxide, with one prototype providing sustained NO release for 5 weeks in pH 7.4 buffer at 37 degrees C. The latter composition, a cross-linked poly-(ethylenimine) that had been exposed to NO, inhibited the in vitro proliferation of rat aorta smooth muscle cells when added as a powder to the culture medium and showed potent antiplatelet activity when coated on a normally thrombogenic vascular graft situated in an arteriovenous shunt in a baboon's circulatory system. The results suggest that polymers containing the [N(O)NO]- functional group may hold considerable promise for a variety of biomedical applications in which local delivery of NO is desired.

A novel approach for detection and classification of mammographic microcalcifications using wavelet analysis and extreme learning machine

The objective of this paper is to reveal the effectiveness of wavelet based tissue texture analysis for microcalcification detection in digitized mammograms using Extreme Learning Machine (ELM). Microcalcifications are tiny deposits of calcium in the breast tissue which are potential indicators for early detection of breast cancer. The dense nature of the breast tissue and the poor contrast of the mammogram image prohibit the effectiveness in identifying microcalcifications. Hence, a new approach to discriminate the microcalcifications from the normal tissue is done using wavelet features and is compared with different feature vectors extracted using Gray Level Spatial Dependence Matrix (GLSDM) and Gabor filter based techniques. A total of 120 Region of Interests (ROIs) extracted from 55 mammogram images of mini-Mias database, including normal and microcalcification images are used in the current research. The network is trained with the above mentioned features and the results denote that ELM produces relatively better classification accuracy (94%) with a significant reduction in training time than the other artificial neural networks like Bayesnet classifier, Naivebayes classifier, and Support Vector Machine. ELM also avoids problems like local minima, improper learning rate, and over fitting.

Evaluation of three new hydrocolloid dressings: retention of dressing integrity and biodegradability of absorbent components attenuate inflammation

Residues from hydrocolloid dressings (HCDs) that originate from matrix disintegration and nonbiodegradability of the absorbent components, may cause deep-seated, unresolved inflammation in tissue that appears otherwise healed. The purpose of this study was to evaluate three new HCDs that were formulated with the goal of attenuating the inflammatory responses that may arise from HCD therapy. Two of the HCDs (A-106 and A-107) consisted of conventional absorbents dispersed in a new maceration-resistant adhesive matrix. The same matrix, mixed with potentially biodegradable dextran microspheres, formed the third dressing (Dextran Bead Dressing [DBD]). In this pilot scale study these novel dressings were evaluated on full-thickness dermal wounds on swine. Restore (Hollister) and DuoDERM CGF (Convatec) dressings were used as controls. Wound healing was evaluated histomorphometrically. Pertinent histologic parameters were ranked from wound tissue that was harvested 18 days after wounding. Grossly visible dressing disintegration ranged from minimal (DBD) to severe (Restore). Disintegration of other dressings was moderate. The percentage of tissue sections exhibiting giant cells reflected, in parallel, the observed extent of dressing disintegration. Thirty-eight percent of wounds dressed with DBD contained giant cells; 74 and 100% of wounds treated with DuoDERM CGF and Restore, respectively, contained giant cells. DBD-dressed wounds had relatively fewer chronic inflammatory cells than other dressings. These wounds were also characterized by a well-organized collagen matrix and complete reepithelialization. The extent of wound closures was similar for all dressing types except Restore. Closure of Restore-dressed wounds was delayed compared with closure with DBD and DuoDERM CGF on all days of evaluation except one. A-106 and A-107 were comparable to DuoDERM CGF in retention of dressing integrity and the elicited inflammatory tissue response. The DBD dressing appears to possess equivalent properties of typical HCDs while causing minimal tissue reactions.

Expression and secretion of TGF-beta isoforms and expression of TGF-beta-receptors I, II and III in normal and neoplastic human breast

We investigated gene expression of the TGF-beta signalling system (including peptides and receptors) in normal and malignant breast tissue. Additionally, gene and protein expression was determined in a series of primary epithelial and stromal cultures derived from these tissues. TGF-beta isoforms and their receptors were expressed by both tissue sets, however the percentage of samples expressing each transcript varied. In normal breast, both TGF-beta1 and TGF-beta3 were found in most samples (88 and 89% respectively), with fewer expressing TGF-beta2 (68%). A similar pattern was evident in the tumours. Type I receptor of TGF-beta was constitutively expressed in normal breast and observed in most tumours (90%). Type II and III receptors of TGF-beta were expressed less frequently, although the type II receptor was mainly expressed by tumours (P=0. 0075). All primary cultures produced TGF-beta1 and TGF-beta2. Comparing respective cell populations, tumour stromal cells produced significantly more TGF-beta1 than those derived from normal breast (P<0.0001). Linear regression analysis showed stromal cultures derived from breast tumours exhibited a strong positive correlation (r=0.976) in the production of TGF-beta1 and TGF-beta2. Thus, TGF-beta and TGF-beta-receptors are widely and differentially expressed by normal and malignant breast and secretion of this peptide by epithelial and stromal cultures, in particular those derived from tumours, confirms its potential as an autocrine/paracrine regulator in breast cancer.

Preparation of a Dextran-Based Degradable Absorbent Suitable for Wound Healing Applications

Hydrolytically degradable microspheres were prepared by crosslinkng dextran under alkaline conditions with cyanogen bromide (CNBr). The crosslinking was performed in a water-in-oil type heterophase suspension medium. Dextran Mws of 500,000 and 40,000 were used for the preparations, CNBr:dextran-OH mole ratios ranged from 0.021:1 to 0.21:1. The microspheres absorbed significant quantities of water (20-45 times their own weight), and were shown to degrade in neutral buffer to soluble and non-toxic products. Hydration and degradation behavior varied linearly with the ratios of CNBr to dextran. The physical properties were dependent on the molecular weights of the dextrans used in the preparations. In contrast to epichlorohydrin crosslinked dextran microspheres that are resistant to hydrolysis and only degrade enzymatically, the described microspheres degrade more rapidly by simple hydrolysis of the iminocarbonate bonds that constitute the microspheres. Such degradative properties are ideal in the application of the microspheres as wound filers and as components of wound dressings.

Rare Case of Left Ventricular Thrombus Postmyocardial Infarction for Emergency Decompressive Craniectomy

Left ventricular (LV) thrombus formation is a notorious complication encountered in postmyocardial infarction patients. Such cases, when coming for noncardiac surgery, put the patient at greater risk of embolic events. Anesthesiologists play a pivotal role in the management of such rare and difficult cases. There is sparse evidence on management of such cases for noncardiac surgery. Hence, we would like to share our experience of a young patient with LV thrombus posted for left decompressive craniectomy.

Role of prophylactic intravenous calcium in prevention of postspinal hypotension among women with preeclampsia undergoing cesarean delivery: a placebo controlled randomized clinical trial

BACKGROUND

Preeclamptic women, in addition to traditional antihypertensive medications, often receive magnesium supplementation and are at increased risk of postspinal hypotension Postspinal hypotension increases the risk of fetomaternal morbidity. Calcium is a physiological antagonist of magnesium in vascular smooth muscle. Therefore, the study hypothesized that calcium is better suited for preserving systemic vascular resistance and preventing postspinal hypotension during cesarean delivery.

OBJECTIVES

The study aimed to evaluate the effect of prophylactic calcium administration on postspinal hypotension in preeclamptic women receiving magnesium supplementation.

METHODS

This prospective, randomized, placebo-controlled, double-blinded, two-arm parallel trial was conducted in preeclamptic women receiving magnesium sulfate supplementation undergoing cesarean delivery. The women were randomized to receive intravenous calcium or a placebo (normal saline) before spinal anesthesia. The study drug (calcium gluconate 500 mg or normal saline) was administered over 15 minutes and ended immediately before spinal anesthesia. The primary outcome measure was the incidence of postspinal hypotension, and secondary outcome measures were postpartum blood loss and maternal and neonatal outcomes.

RESULTS

A total of 100 women (50 each calcium and placebo arm) completed the study. The baseline demographic variables, mean blood pressure and heart rate were comparable. The incidence of postspinal hypotension was significantly lower in the calcium arm compared to the placebo arm (32% vs 60%; Relative risk [95% CI]; 1.87 [1.18-2.97]; P=.007). The mean phenylephrine requirement (5.60±14.59 vs 14.80±22.42 mcg; P=.01) and mephentermine requirement (3.30±5.11 mg vs 5.82±4.97 mg; P=.008) was significantly lower in the calcium group. Furthermore, the calcium group's mean postpartum blood loss was significantly lower (406.90±94.34 vs 472.20±122.49 ml, P=.004). However, the Neonatal Intensive Care Unit admission rate, Apgar score, umbilical artery PH, and maternal serum calcium were comparable.

CONCLUSION

Prophylactic calcium infusion significantly reduces the incidence of postspinal hypotension during cesarean delivery in preeclamptic women receiving magnesium supplementation. Furthermore, the effect of prophylactic calcium in decreasing postpartum blood loss is encouraging. However, large trials are required to validate the findings of this study.