Dynamics of a polymer chain confined in a membrane

We present a Brownian dynamics theory with full hydrodynamics (Stokesian dynamics) for a Gaussian polymer chain embedded in a liquid membrane which is surrounded by bulk solvent and walls. The mobility tensors are derived in Fourier space for the two geometries, namely, a free membrane embedded in a bulk fluid, and a membrane sandwiched by the two walls. Within the preaveraging approximation, a new expression for the diffusion coefficient of the polymer is obtained for the free-membrane geometry. We also carry out a Rouse normal mode analysis to obtain the relaxation time and the dynamical structure factor. For large polymer size, both quantities show Zimm-like behavior in the free-membrane case, whereas they are Rouse-like for the sandwiched membrane geometry. We use the scaling argument to discuss the effect of excluded-volume interactions on the polymer relaxation time.

Role of SLC5A8, a plasma membrane transporter and a tumor suppressor, in the antitumor activity of dichloroacetate

There has been growing interest among the public and scientists in dichloroacetate as a potential anticancer drug. Credible evidence exists for the antitumor activity of this compound, but high concentrations are needed for significant therapeutic effect. Unfortunately, these high concentrations produce detrimental side effects involving nervous system, thereby precluding its use for cancer treatment. The mechanistic basis of the compound’s antitumor activity is its ability to activate pyruvate dehydrogenase complex through inhibition of pyruvate dehydrogenase kinase. Since the compound inhibits the kinase at micromolar concentrations, it is not known why therapeutically prohibitive high doses are needed for suppression of tumor growth. We hypothesized that lack of effective mechanisms for the entry of dichloroacetate into tumor cells may underlie this phenomenon. Here we show that SLC5A8 transports dichloroacetate very effectively with high affinity. This transporter is expressed in normal cells, but the expression is silenced in tumor cells via epigenetic mechanisms. The lack of the transporter makes tumor cells resistant to the antitumor activity of dichloroacetate. However, if the transporter is expressed in tumor cells ectopically, the cells become sensitive to the drug at low concentrations. This is evident in breast cancer cells, colon cancer cells, and prostate cancer cells. Normal cells, which constitutively express the transporter, are however not affected by the compound, indicating the tumor cell-selective therapeutic activity. The mechanism of the antitumor activity of the compound is still its ability to inhibit pyruvate dehydrogenase kinase and force mitochondrial oxidation of pyruvate. Since the silencing of SLC5A8 in tumors involves DNA methylation and its expression can be induced by treatment with DNA methylation inhibitors, our findings suggest that combining dichloroacetate with a DNA methylation inhibitor would offer a means to reduce the doses of dichloroacetate to avoid detrimental effects associated with high doses but without compromising antitumor activity.

Characterization of HCV-specific CD4+Th17 immunity in recurrent hepatitis C-induced liver allograft fibrosis

Hepatitis C virus (HCV) recurrence with accelerated fibrosis following orthotopic liver transplantation (OLT) is a universal phenomenon. To evaluate mechanisms contributing to HCV induced allograft fibrosis/cirrhosis, we investigated HCV-specific CD4+Th17 cells and their induction in OLT recipients with recurrence utilizing 51 HCV+ OLT recipients, 15 healthy controls and 9 HCV- OLT recipients. Frequency of HCV specific CD4+ Tcells secreting IFN-γ, IL-17 and IL-10 was analyzed by ELISpot. Serum cytokines and chemokines were analyzed by LUMINEX. Recipients with recurrent HCV induced allograft inflammation and fibrosis/cirrhosis demonstrated a significant increase in frequency of HCV specific CD4+Th17 cells. Increased pro-inflammatory mediators (IL-17, IL-1β, IL-6, IL-8 and MCP-1), decreased IFN-γ, and increased IL-4, IL-5 and IL-10 levels were identified. OLT recipients with allograft inflammation and fibrosis/cirrhosis demonstrated increased frequency of Foxp3+ regulatory T cells (Tregs) that inhibited HCV specific CD4+Th1 but not Th17 cells. This suggests that recurrent HCV infection in OLT recipients induces an inflammatory milieu characterized by increased IL-6, IL-1β and decreased IFN-γ which facilitates induction of HCV specific CD4+Th17 cells. These cells are resistant to suppression by Tregs and may mediate an inflammatory cascade leading to cirrhosis in OLT recipients following HCV recurrence.

Source apportionment of the ionic components in precipitation over an urban region in Western India

INTRODUCTION

Inorganic ion concentrations in event-based wet-only precipitation samples collected during the south-west (SW) monsoon at an urban location in Western India, Ahmedabad between July 2000 and September 2002 were measured by Rastogi and Sarin (2007).

METHODS

For the first time at a location in India, an advanced factor analysis model was retrospectively applied to the measured concentrations of ions (Rastogi and Sarin 2007) in precipitation for source apportionment. Positive matrix factorization resolved five factors, including crustal material, sea salt, nitrate/sulfate-rich factor, ammonium-rich factor, and free acidity.

RESULTS AND DISCUSSION

Amongst the model-resolved factors, crustal material was the highest contributor to the total dissolved solids (TDS) accounting for 44.1% on average. Potential source contribution function (PSCF) analysis identified source locations along the eastern coast of Somalia, Yemen, Oman, and the United Arab Emirates for this factor. Sea salt was the second highest contributor accounting for 29.8%. The potential source regions of this factor were also identified in the Arabian Sea and the southern Indian Ocean along the coast of Africa, and the Arabian Gulf. This study also examined the spatial relationships between the source locations of chemical species in precipitation and in ambient aerosol (resolved in an earlier study).

CONCLUSIONS

Crustal material was the highest contributor to TDS at the study location. Spatial relationships between aerosol and precipitation factor source regions suggested that below-cloud scavenging of aerosol particles was a likely contributor to the chemical species apportioned to various precipitation factors. Additionally, source types of chemical species in precipitation resolved in this study were qualitatively compared with those identified at other locations in India. The comparison showed that soil was an important contributor to the dissolved mass of chemical species in precipitation at all locations in India.

Contributions of Indian conservative dentists and endodontists to the Medline database during 1996-2009: A bibliometric analysis

BACKGROUND

Analysis of publication trends will guide the policy framers, administrators, and dentists to frame future policies and design programs for the development of scientific and technological policies in the field of dentistry.

AIMS AND OBJECTIVES

This study was undertaken to assess the trends in Indian Conservative dentists and endodontists' Publication in PubMed-Medline database during 1996-2009.

MATERIALS AND METHODS

Using the time limitation of publication date limit of 1(st) January 1996 to 31(st) December 2009, all articles where authors' affiliation had the words Dental AND India were selected. From this collection of articles, the following were noted down: year of publication, number of authors, name of the journal, reach of the journal, status of the journal, specialty of the first, state of origin, and type of research. From this database, the performance of department of conservative dentistry and endodontics was analyzed.

RESULTS

The number of articles published by conservative dentists and endodontists was 124. Among them, 63 got published in international journals and 61 in Indian journals. A majority of 33 journals were published in Indian Journal of Dental Research followed by 25 in the Journal of Conservative Dentistry. Out of these articles, 66 were on the basis of original research done by the authors. Nearly 45.2% of the published articles were from the institutes in Tamil Nadu, followed by Karnataka (30.6%), and Maharashtra (8.1%). Although the overall distribution of the publication trends seems to be constant from 1996 to 2006, there seems to be boom in the publication trend since 2007.

Paradoxical decrease in HDL-cholesterol and apolipoprotein A1 with simvastatin and atorvastatin in a patient with type 2 diabetes

Statins are agents widely used to lower LDL-cholesterol (LDL-C) in primary and secondary prevention of coronary heart disease. The five statins available in the UK (simvastatin, pravastatin, fluvastatin, atorvastatin and rosuvastatin) differ in many of their pharmacologic properties. In addition to lowering LDL-C, statins also increase HDL-cholesterol (HDL-C) moderately. There have been rare reports of significant HDL-C decreases in patients commenced on fibrates and when thiazolidinediones are added to fibrates. This is known as a 'paradoxical HDL-C decrease' as both groups of agents usually increase HDL-C. This phenomenon has never been clearly documented following statin therapy. We now describe a patient with type 2 diabetes who showed this paradoxical fall in HDL-C (baseline HDL-C: 1.8 mmol/L; on simvastatin 40 mg HDL-C 0.6 mmol/L; on atorvastatin 20 mg HDL-C 0.9 mmol/L) with a similar decrease in apolipoprotein A1. No similar decrease was observed with pravastatin and rosuvastatin therapy. This phenomenon appeared to be associated with statin treatment and not a statin/fibrate combination. Our patient clearly demonstrated a paradoxical HDL-C fall with simvastatin and atorvastatin, but not pravastatin or rosuvastatin. Simvastatin and atorvastatin share many pharmacokinetic properties such as lipophilicity while pravastatin and rosuvastatin are relatively hydrophilic and are not metabolized by cytochrome P450 3A4. However, these characteristics do not explain the dramatic reductions in HDL-C observed.

Spiral CT diagnosis and endodontic management of an anatomically variant palatal root with two canals in a maxillary first molar

This case report presents the endodontic management of an anatomically variant palatal root with 2 canals (Vertucci type II) in a maxillary first molar, which was confirmed with the help of spiral computed tomography (SCT). This serves to remind clinicians that such anatomic variations should be taken into account during the endodontic treatment of maxillary molars and highlights the invaluable aid of the SCT in accurate diagnosis and in negotiating the complex morphologic variations in root canals, thus enabling successful endodontic management.

A higher-order-mode erbium-doped-fiber amplifier

We demonstrate the first erbium-doped fiber amplifier operating in a single, large-mode area, higher-order mode. A high-power, fundamental-mode, Raman fiber laser operating at 1480 nm was used as a pump source. Using a UV-written, long-period grating, both pump and 1564 nm signal were converted to the LP(0,10) mode, which had an effective area of 2700 microm(2) at 1550 nm. A maximum output power of 5.8 W at 1564 nm with more than 20 dB of gain in a 2.68 m long amplifier was obtained. The mode profile was undistorted at the highest output power.

Source identification of ambient aerosols over an urban region in western India

A first-of-its-kind source apportionment study of the Ahmedabad, India aerosol was conducted in order to determine the major sources contributing to the measured total suspended particles (TSPs). TSP samples were collected approximately once every ten days between May 2000 and January 2003, and analyzed for TSP mass, anions, cations, and elemental concentrations. An advanced factor analysis technique, positive matrix factorization (PMF) was applied to the measured concentrations and six factors were resolved. The model resolved factors included airborne regional dust, calcium carbonate rich dust, biomass burning/vehicular emissions, secondary nitrate/sulfate, marine aerosol, and smelter. Among the resolved factors, airborne regional dust was the highest contributor to the measured TSP mass followed by calcium carbonate rich dust with their average contributions accounting for 57.9 and 19.0%, respectively. Thus, crustal factors were the most dominant sources of TSP in Ahmedabad accounting for nearly 77% of the mass. Potential source contribution function (PSCF) analysis identified parts of Madhya Pradesh and Uttar Pradesh, regions in southwestern Pakistan along the Indo-Gangetic Plain (IGP), and southern Iran as potential source locations for the airborne regional dust factor. In contrast, Rajasthan and Madhya Pradesh, and parts of northern Pakistan were identified as potential source locations for the calcium carbonate rich dust factor. It is hypothesized that aerosol contributions from several limestone quarries in Rajasthan and Madhya Pradesh may have resulted in this factor being calcium carbonate enriched.

Drag coefficient of a liquid domain in a two-dimensional membrane

Using a hydrodynamic theory that incorporates a momentum decay mechanism, we calculate the drag coefficient of a circular liquid domain of finite viscosity moving in a two-dimensional membrane. We derive an analytical expression for the drag coefficient which covers the whole range of domain sizes. Several limiting expressions are discussed. The obtained drag coefficient decreases as the domain viscosity becomes smaller with respect to the outer membrane viscosity. This is because the flow induced in the domain acts to transport the fluid in the surrounding matrix more efficiently.