Polyester-based biodegradable plastics: an approach towards sustainable development.

Non-degradability of conventional plastics, filling of landfill sites, raising water and land pollution and rapid depletion of fossil resources have raised the environmental issues and global concerns. The current demand and production of plastics is putting immense pressure on fossil resources, consuming about 6% of the global oil and is expected to grow up to 20%. The polyester-based biodegradable plastics (BPs) are considered as a remedy to the issue of plastics waste in the environment. BPs appear to manage the overflow of plastics by providing new means of waste management system and help in securing the non-renewable resources of nature. This review comprehensively presents the environmental burdens due to conventional plastics as well as production of polyester-based BPs as an alternative to conventional commodity plastics. The diversity of micro-organisms and their enzymes that degrade various polyester-based BPs (PLA, PCL, PHB/PHBV and PET) has also been described in detail. Moreover, the impact of plastics degradation products on soil ecology and ecosystem functions has critically been discussed. The report ends with special focus on future recommendations for the development of sustainable waste management strategies to control pollution due to plastics waste. SIGNIFICANCE AND IMPACT OF THE STUDY: Polyester-based BPs considered as a solution to current plastic waste problem as well as leading polymers in terms of biodegradability and sustainability has been critically discussed. The role of microorganisms and their enzymes involved in the biodegradation of these polymers and ecotoxicological impact of degradation products of BPs on soil microbial community and biogeochemical cycles has also been described. This report will provide an insight on the key research areas to bridge the gap for development of simulated systems as an effective and emerging strategy to divert the overflow of plastic in the environment as well as for the greener solution to the plastic waste management problems.

Assessment of deep venous thrombosis using routine pelvic CT.

OBJECTIVE: The purpose of this study was to assess routine pelvic CT both for accuracy in diagnosis of deep venous thrombosis and for frequency of detection of clinically unsuspected pelvic thrombi. MATERIALS AND METHODS: We reviewed the CT records of patients who had undergone pelvic CT during a 6-month period and cross-referenced these records to reports on lower extremity venous sonography to identify patients who had undergone this test within 1 week of pelvic CT. We compared the frequency and location of venous thrombosis revealed through these two tests. To identify unsuspected deep venous thrombosis detected on pelvic CT, we reviewed the charts of patients for whom a clot was reported to determine if it had been clinically suspected before CT. RESULTS: Among the 52 patients who underwent both CT and lower extremity venous sonography, the findings were in agreement for 49 (94%). The techniques disagreed for three patients; two patients had deep venous thrombosis detected on sonography but not on CT and the other had a clot detected on CT but not on sonography. The prevalence of unsuspected deep venous thrombosis detected by CT was 1.1%, and 73% of these patients underwent anticoagulation therapy without further confirmatory tests. CONCLUSION: Unsuspected deep venous thrombosis is commonly seen on routine pelvic CT and should be carefully sought during such examinations. CT appears to be relatively accurate in the detection of deep venous thrombosis. Thus, CT venography combined with pulmonary CT angiography may significantly increase the percentage of patients who are appropriately treated for thromboembolic disease because both deep venous thrombosis and pulmonary emboli can be identified by this combined test.

The in vivo assessment of nimesulide cyclooxygenase-2 selectivity.

In man, nimesulide selectively inhibits cyclooxygenase-2 (COX-2) with little effect on haemostatic function or gastric prostaglandin formation. It causes significantly less gastrointestinal injury than naproxen, but has anti-inflammatory efficacy similar to that of naproxen and other currently available non-steroidal anti-inflammatory drugs. Naproxen suppressed arachidonic-acid-mediated platelet aggregation, reduced serum thromboxane B2 levels by 98% throughout the treatment period and reduced gastric mucosal prostaglandins (PGE2 and 6-keto-PGF1alpha) production by an average of 80%. This contrasts with nimesulide: platelet aggregation was not significantly affected, thromboxane B2 levels were only 29% lower and the gastric mucosal prostaglandins were inhibited in the order of approximately 20%. During the treatment period, both nimesulide and naproxen significantly inhibited COX-2-dependent PGE2 synthesis in the whole blood; however, naproxen had a lesser effect than nimesulide.

Effect of cardiac surgery on ventricular septal motion: assessment by intraoperative echocardiography and cross-sectional two-dimensional echocardiography.

Echocardiographic evidence of paradoxical septal motion frequently occurs after cardiac surgery. To assess possible etiologic factors 17 patients were studied preoperatively, intraoperatively, and 7 days after surgery. Preoperative septal motion was normal in 14 and paradoxical in three (two with previous cardiac surgery, one with atrial septal defect [ASD]). Intraoperative septal motion prior to surgical procedure was normal in 16 and paradoxical in one (ASD). Septal motion (excursion and thickening fraction) was normal in all patients prior to chest closure. Echocardiograms of adequate quality were obtained at 7 days post surgery in 15 patients; septal motion was paradoxical in nine (group A) and normal in six (group B). No significant differences were seen between the two groups in ischemic time or in the preoperative to postoperative change in left ventricular (LV) and right ventricular diastolic dimension, shortening fraction, or septal and posterior wall thickening fraction. A significant postoperative decrease in septal excursion was seen in group A but not in group B; significant postoperative increases in posterior wall excursion were seen in both groups. Cross-sectional two-dimensional echocardiograms performed in 20 patients (8 normal, 12 postoperative paradoxical septal motion) were analyzed. In normal controls no significant change was detected in the LV centroid position during systole. In contrast, the 12 postoperative patients showed significant anterior displacement of the LV centroid and right septum during systole. Thus, paradoxical septal motion after cardiac surgery appears to relate to excessive anterior cardiac mobility due to pericardiotomy rather than to myocardial ischemia resulting from cardiopulmonary bypass.