Redox polymerization, 3. Kinetics of acrylonitrile polymerization initiated by the redox systems cyanoacetic acid/Mn(III) and 2-butanone/Mn(III) in aqueous sulfuric acid

The kinetics of Polymerization of acrylonitrile initiated by the redox systems cyanoacetic acid/Mn(III) and 2-butanone/Mn(III) were investigated in the temperature range of 30 – 50°C in aqueous sulfuric acid. The kinetics are consistent with the formation of a 1 : 1 complex between the reducing agent and Mn(III), its unimolecular decomposition yielding the initiating radical. Extensive oxidation of the primary radical with exclusively mutual termination of growing radicals accounts for the kinetics of the polymerization. Rate and equilibrium constants as well as thermodynamic parameters were evaluated and their significance is discussed.     

Peripheral giant cell granuloma--a case report

Peripheral giant cell granuloma is a lesion arising mainly from the connective tissue of gingiva or periosteum of alveolar ridge. A case of peripheral giant cell granuloma involving a deciduous molar and the succedaneous tooth is reported. The lesion was large and interfered with occlusion. Surgical excision of the lesion along with the deciduous first molar was done. The underlying permanent first premolar was also involved, and had to be removed. The importance of an adequate salivary flow and maintenance of oral hygiene in the prevention of such lesions is stressed.     

Chemical modification of poly(vinyl chloride) resin using poly(ethylene glycol) to improve blood compatibility

Poly(vinyl chloride) (PVC) was aminated by treating the resin with a concentrated aqueous solution of ethylenediamine. The aminated PVC was then reacted with hexamethylene diisocyanate to incorporate the isocyanate group onto the polymer backbone. The isocyanated PVC was further reacted with poly(ethylene glycol) (PEG) of molecular weight 600 Da. The modified polymer was characterized using infrared and X-ray photoelectron spectroscopy (XPS) and thermal analysis. Infrared and XPS spectra showed the incorporation of PEG onto PVC. The thermal stability of the modified polymer was found to be lowered by the incorporation of PEG. Contact angle measurements on the surface of polymer films cast from a tetrahydrofuran solution of the polymer demonstrated that the modified polymer gave rise to a significantly hydrophilic surface compared to unmodified PVC. The solid/water interfacial free energy of the modified surface was 3.9 ergs/cm(2) as opposed to 18.4 ergs/cm(2) for bare PVC surface. Static platelet adhesion studies using platelet-rich plasma showed significantly reduced platelet adhesion on the surface of the modified polymer compared to control PVC. The surface hydrophilicity of the films was remarkably retained even in the presence of up to 30 wt% concentration of the plasticizer di-(2-ethylhexyl phthalate). The study showed that bulk modification of PVC with PEG using appropriate chemistry can give rise to a polymer that possesses the anti-fouling property of PEG and such bulk modifications are less cumbersome compared to surface modifications on the finished product to impart anti-fouling properties to the PVC surface.     

Conjugating doxorubicin to polymannose: a new strategy for target specific delivery to lung cancer cells

Abstract

As mannose receptors are known to be over-expressed in cancer cells, we synthesized polymannose-doxorubicin (PM-DOX) conjugates with the objective of targeting the drug to cancer cells. DOX was conjugated to oxidized PM through Schiff’s linkages to obtain PM-DOX conjugates. In order to examine the superior targeting efficacy of PM-DOX conjugate, sodium alginate (SA) was conjugated to DOX by similar chemistry and compared with PM-DOX conjugate. The cytotoxicity of the conjugates was investigated in A549 cell lines using MTT Assay and the cell uptake and retention studies, were performed using flow cytometry and cell imaging. In vitro drug release studies with both PM-DOX and SA-DOX conjugates showed an initial burst release of DOX up to 37–39% at 1?h, followed by a steady release up to 58–62% at 24?h in human plasma while negligible release was observed in phosphate buffered saline. The conjugates exhibited negligible hemolytic potential to human erythrocytes compared to free DOX. The PM-DOX conjugate showed better cytotoxic potential against A549 cells at lower concentration (equivalent to 0.27?μg/mL of DOX) at 72?h compared to free DOX and SA-DOX conjugate. Further, PM-DOX conjugate showed enhanced uptake by the cells in comparison with SA-DOX conjugate thereby confirming the target specificity of PM to the cancer cells.     

Microfoam Sclerotherapy for Varicose Veins: a Retrospective Analysis of a Modified Technique

Varicose veins (VVs) are generally characterized by their elongated, twisted, bulging, superficial appearance on the lower extremities and usually present with acute or chronic venous diseases. Despite diagnostic and surgical advances in the management of VV, patients suffer from post-therapeutic complications and recurrence. We present findings from a retrospective study of a modified treatment modality in patients with varicose veins who attended St. Thomas Institute of Research on Venous Diseases, Changanassery, Kerala. The hospital caters to patients from India and outside. Out of 14,707 patients treated from 1997 till May 2013, 6,350 patients from January to March 2011 were selected for the study from the routine clinical practice (mid-segment) to facilitate follow-up. They were categorized according to Clinical Etiologic Anatomic Pathophysiologic (CEAP) clinical classification system. Baseline data were accrued using a questionnaire. Patients were treated by microfoam sclerotherapy giving a maximum importance to smaller veins, depicting a modified technique of microfoam sclerotherapy (MMFST). This is based on the significance of microscopic venous valves (MVVs) in the development of chronic venous disease (CVD). Follow-up was according to a predefined schedule, and improvements and complications were recorded. A positive family history of VVs was reported in 85.23 % of patients. Half the study population belonged to CEAP clinical class IV. There were no significant complications in patients throughout the 2 to 6 years of follow-up. Recurrence was rarely reported during follow-up and was corrected by repeating the procedure as required during follow-up. MMFST is an innovation in the treatment of VVs based on new principles, with the potential to control and revert the symptoms of CVD, with minimal complications.     

Cost Effectiveness of Routine Laparoscopic Ultrasound for Assessment of Resectability of Gallbladder Cancer

Background

In addition to a diagnostic laparoscopy (DL), a routine laparoscopic ultrasound (LUS) has been proposed to identify undetected hepatic metastases and/or anatomically advanced disease in patients with T2 or higher gall bladder cancer (GBC) patients planned for surgical resection. It was hypothesized that a routine LUS is not a cost-effective strategy for these patients.

Methods

Decision tree modeling was undertaken to compare DL-LUS vs. DL at the time of definitive resection of GBC (with no prior cholecystectomy). Costs in US dollars (payer’s perspective), quality-adjusted life weeks (QALWs), and incremental cost-effectiveness ratios (ICER) were calculated (horizon: 6 weeks, willingness-to-pay: $1,000/QALW or $50,000/QALY).

Results

DL-LUS was cost effective at the base case scenario (costs: $30,838 for DL vs. $30,791 for DL-LUS and effectiveness 3.81 QALWs DL vs. 3.82 QALW DL-LUS), resulting in a cost reduction of $9,220 per quality-adjusted life week gained (or $479,469 per QALY). DL-LUS became less cost effective as the cost of ultrasound increased or the probability of exclusion from resection decreased.

Conclusions

Routine LUS with DL for the assessment of resectability and exclusion of metastases is cost effective for patients with GBC. Until improvements in preoperative imaging occur to decrease the probability of exclusion, this appears to be a feasible strategy.     

Varicella zoster meningitis in a pregnant woman with acquired immunodeficiency syndrome

Between 6000 and 7000 women in the United States infected with human immunodeficiency virus (HIV) give birth annually. It is well known that HIV-related immunosuppression significantly increases the risk for acquiring opportunistic infections (OIs). However, there is limited information regarding the relationship of pregnancy in the setting of HIV/AIDS infection, subsequent development of OIs, and maternal and fetal outcomes. A pregnant 36-year-old woman with AIDS was diagnosed with varicella zoster meningitis. Weight-based therapy with acyclovir was initiated with clinical improvement in symptoms. Care of a pregnant HIV-infected patient with an OI poses a unique diagnostic and therapeutic challenge for clinicians. Early diagnosis and initiation of appropriate treatment may provide an opportunity to improve both maternal and fetal outcomes.     

Radiation grafting of hydrophilic monomers on to plasticized poly(vinyl chloride) sheets. II. Migration behaviour of the plasticizer from N-vinyl pyrrolidone grafted sheets

The grafting of N-vinyl pyrrolidone, a hydrophilic monomer, on to flexible poly(vinyl chloride) sheets used in medical applications using ionizing radiation from a 60Co source was studied. The graft yield was found to increase linearly with monomer concentration and also with increasing radiation doses. The migration of the plasticizer di-(2-ethylhexyl)phthalate into a strong organic extractant such as n-hexane was studied at different time intervals for different grafted systems of poly(vinyl chloride) at 30 degrees C. The results indicated a drastic reduction in the leaching of the plasticizer from grafted systems versus ungrafted controls. Incorporation of ethylene dimethacrylate cross-linker during grafting did not seem to affect the graft yield considerably but appeared to further reduce the plasticizer migration. Surface energy calculations of the grafted samples indicate that the surfaces are highly hydrophilic compared to ungrafted poly(vinyl chloride) and the polar and dispersion components tend to vary with increasing cross-linker concentration.     

Subtraction helical CT angiography of intra- and extracranial vessels: technical considerations and preliminary experience

BACKGROUND AND PURPOSE: Reported CT angiographic (CTA) subtraction methods are not simple, robust, or real time. We investigated a novel technique for semiautomated digital subtraction CTA of the intracranial and extracranial arteries. METHODS: Thirty patients underwent precontrast (low milliampere-seconds) and postcontrast (pitch, 1.5; collimation, 1-2.5 mm) helical imaging with a vacuum-type head holder to facilitate image registration and minimize movement. A reconstructed three-dimensional model of the precontrast bone dataset was subtracted from the postcontrast dataset to produce subtracted maximum-intensity-projection angiograms. Experienced (operator 1) and less-experienced (operator 2) staff performed the standard and subtraction reconstructions, and image generation time and quality (graded 1-5) were compared. A third operator blinded to the method assessed the hard-copy image quality. RESULTS: Image quality with subtraction postprocessing was significantly better with both operators (operator 1, mean improvement of 0.87 grade, median improvement of 1 grade, P <.001; operator 2, mean improvement of 0.63 grade, median improvement of 1 grade, P <.001). Hard-copy image quality was better with the subtraction method (operator 1, P >.001; operator 2, P <.001). Blood vessels at the base of the brain were better demonstrated on subtraction images in 13 of 14 examinations. For the less experienced operator, the reconstruction time was significantly less with the subtraction method than with the conventional method (mean, 7.5 vs 10.1 minutes; P =.001). CONCLUSION: When separation of the vasculature from bone is important and technically difficult, digital subtraction CTA offers a potential advantage. This semiautomated technique is fast and easy to learn, and variably experienced staff can use it.     

Versatility of the distally based superficial sural flap for reconstruction of lower leg and foot in children

Twenty children are presented after undergoing a distally based superficial sural flap for coverage of defects at the lower leg and foot. The age of the patients was between 1 and 12 years. Fifteen patients had trauma to the lower leg, with eight of them having associated injuries. Three had postburn contracture and two had pressure sore. In 14 cases, the flap was used as a fasciocutaneous flap, whereas in six cases it was used as a fascial flap covered with a skin graft. The flaps were used to cover the defects from the dorsum of the foot distally up to the mid third of tibia proximally. The mean follow-up was for a period of 2 years. Even though free tissue transfer is reliable and safe for the reconstruction of major leg injuries in children, the distally based superficial sural flap has the advantage of being easy to perform, with short operating time, minimal donor side morbidity, and preservation of major arteries of the leg.