On the rupture of DNA molecule.

Using Langevin dynamics simulations, we study effects of the shear force on the rupture of a double stranded DNA molecule. The model studied here contains two single diblock copolymers interacting with each other. The elastic constants of individual segments of diblock copolymer are considered to be different. We showed that the magnitude of the rupture force depends on whether the force is applied at 3' - 3' - ends or 5' - 5' - ends. Distributions of extension in hydrogen bonds and covalent bonds along the chain show the striking differences. Motivated by recent experiments, we have also calculated the variation of rupture force for different chain lengths. Results obtained from simulations have been validated with the analytical calculation based on the ladder model of DNA.

Fibrous dysplasia and cherubism.

Fibrous dysplasia (FD) is a non-malignant fibro-osseous bony lesion in which the involved bone/bones gradually get converted into expanding cystic and fibrous tissue. The underlying defect in FD is post-natal mutation of GNAS1 gene, which leads to the proliferation and activation of undifferentiated mesenchymal cells arresting the bone development in woven phase and ultimately converting them into fibro-osseous cystic tissue. Cherubism is a hereditary form of fibrous dysplasia in which the causative factor is transmission of autosomal dominant SH3BP2 gene mutation. The disease may present in two distinct forms, a less severe and limited monostotic form, and a more aggressive and more widespread polyostotic form. Polyostotic form may be associated with various endocrine abnormalities, which require active management apart from the management of FD. Management of FD is not free from controversies. While total surgical excision of the involved area and reconstruction using newer micro-vascular technique is the only definitive treatment available from the curative point of view, but this can be only offered to monostotic and very few polyostotic lesions. In polyostotic varieties on many occasions these radical surgeries are very deforming in these slow growing lesions and so their indication is highly debated. The treatment of cranio-facial fibrous dysplasia should be highly individualized, depending on the fact that the clinical behavior of lesion is variable at various ages and in individual patients. A more conservative approach in the form of aesthetic recontouring of deformed bone, orthodontic occlusal correction, and watchful expectancy may be the more accepted form of treatment in young patients. Newer generation real-time imaging guidance during recontouring surgery adds to accuracy and safety of these procedures. Regular clinical and radiological follow up is required to watch for quiescence, regression or reactivation of the disease process. Patients must be warned and watched for any sign of nerve compression, especially visual impairment due to optic nerve compression. Rather than going for prophylactic optic canal decompression (which does more harm than good), optic nerve decompression should be done in symptomatic patients only, and preferably be done via minimal invasive endoscopic neuro-surgical approach than the conventional more morbid open craniotomy approach. There is growing research and possibilities that newer generation bisphosphonate medication may change the management scenario, as these medications show encouraging response in not only reducing the osteoclastic activity, but simultaneously also stimulating the osteoblastic and osteocytic activities. The explosion of genetic research and stem cell therapy may lead to better understanding and subsequently better treatment of FD in future.

pH dependent poly[2-(methacryloyloxyethyl)trimetylammonium chloride-co-methacrylic acid]hydrogels for enhanced targeted delivery of 5-fluorouracil in colon cancer cells.

Stimuli responsive hydrogels have shown enormous potential as a carrier for targeted drug delivery. In this study we have developed novel pH responsive hydrogels for the delivery of 5-fluorouracil (5-FU) in order to alleviate its antitumor activity while reducing its toxicity. We used 2-(methacryloyloxyethyl) trimetylammonium chloride a positively charged monomer and methacrylic acid for fabricating the pH responsive hydrogels. The released 5-FU from all except hydrogel (GEL-5) remained biologically active against human colon cancer cell lines [HT29 (IC50 = 110-190 µg ml(-1)) and HCT116 (IC50 = 210-390 µg ml(-1))] but not human skin fibroblast cells [BJ (CRL2522); IC50 ≥ 1000 µg ml(-1)]. This implies that the copolymer hydrogels (1-4) were able to release 5-FU effectively to colon cancer cells but not normal human skin fibroblast cells. This is probably due to the shorter doubling time that results in reduced pH in colon cancer cells when compared to fibroblast cells. These pH sensitive hydrogels showed well defined cell apoptosis in HCT116 cells through series of events such as chromatin condensation, membrane blebbing, and formation of apoptotic bodies. No cell killing was observed in the case of blank hydrogels. The results showed the potential of these stimuli responsive polymer hydrogels as a carrier for colon cancer delivery.

Salivary parameters and their correlation with neutrophil counts in children with acute lymphoblastic leukemia.

BACKGROUND: Chemotherapy for Acute Lymphoblastic Leukemia (ALL) is known to render children immuno-deficient. A concomitant suppression of local defence mechanisms, such as saliva may further aggravate the adverse consequences of chemotherapy. The present study was conducted to evaluate alterations in salivary flow rate, pH and buffering capacity and to correlate these parameters with Absolute Neutrophil Counts (ANC). METHODS: A cohort of 43 patients, aged 3-12 years were evaluated for the aforementioned parameters at baseline, post-induction and post-consolidation phases. Salivary collection was done and ANC was measured from routine haematological reports. RESULTS: A decrease in the salivary parameters was observed at the end of Induction phase as compared to baseline, with a statistically significant decrease in unstimulated salivary flow rates (p < 0.01). Statistically significant positive correlations were found between ANC and salivary flow rate (p = 0.005), pH (p < 0.00) and buffering capacity (p < 0.00). On testing the significance of these correlations, all the values for these parameters were found to be statistically significant. CONCLUSION: Salivary parameters showed derangements over the phases of chemotherapy, with maximum decrease at the end of induction phase. The positive correlations of salivary parameters with ANC of the subjects may be considered indicative of a concomitant immunological compromise in these children.

A simple technique to mitigate microplastic pollution and its mobility (via ballast water) in the global ocean.

Ballast water transport is considered as one of the major vectors for dispersal of microplastics around the global oceans. In this commentary, a simple, inexpensive solution has been proposed to reduce microplastic pollution and its mobility via ballast water. A screening chamber (with stainless steel three layered mesh) is proposed to be attached to the existing Ballast Water Treatment Systems (BWTSs) in cargo ships to filter back-flushed sea water from BWTSs. The three layered screens (500, 300 and 100 µm) will not only avoid clogging and easy separation of different size groups of microplastic particles but also help in smooth discharge of water to the sea. This technique is expected to remove a large number of microplastic particles (ranging from 0.0015 to 1020 million) from a single voyage. The proposed chamber may help to collect 0.0003-204 metric tons of particles/day, depending upon the geographical location of ballast intake in the global ocean. These estimations were made by considering a daily turnover of 0.033 billion tonnes of ballast water globally. This proposed screening chamber attached to the existing BWTSs in cargo ships, along with other region-specific ocean cleaning initiatives, will help in mitigating microplastic pollution in the global ocean.

Seasonal appearance of Chlorophyceae phytoplankton bloom by river discharge off Paradeep at Orissa Coast in the Bay of Bengal.

Characteristics of the monsoonal bloom of phytoplankton at Orissa Coast in the Bay of Bengal were studied through bimonthly observation from April 2001 to December 2002. Three photosynthetic pigments chlorophyll-a (Chl a), chlorophyll-b (Chl b) and carotenoid (Car) were analyzed by absorption spectroscopic method. The seasonal variation of Chl a included phytoplankton bloom in the coastal area during monsoon period. The water column integrated Chl a reached to 68 mg m(-2) at the station-1(St1), and amounted to 20 mg m(-2) at 30 km off the river mouth during August 2001. In contrast the same amount was found at 15 km off the Mahanadi river mouth during August 2002. Salinity during this period varied from 5 psu at the St1 to 27 psu at the edge of the bloom area. The total amount of river discharge in the monsoon period calculated from daily river discharge data reported by Water Resources Department in India was 84 x 10(9) m(3) during 2001 and 20 x 10(9) m(3) during 2002. Both nitrate and phosphate concentrations showed negative quadratic relationship with salinity throughout the observation period. Extrapolated nitrate and phosphate concentration discharge from the Mahanadi river were 10.8 and 4 microg-at l(-1), respectively. Microscopic identification revealed dominance of fluvial Chlorophyceae and diatoms during the monsoon period showing influence of the freshwater discharge.

Bioactive molecules from amphibian skin: their biological activities with reference to therapeutic potentials for possible drug development.

The amphibian skin contains various bioactive molecules (peptides, proteins, steroids, alkaloids, opiods) that possess potent therapeutic activities like antibacterial, antifungal, antiprotozoal, antidiabetic, antineoplastic, analgesic and sleep inducing properties. Research on amphibian skin derived biomolecules can provide potential clue towards newer drug development to combat various pathophysiological conditions. An overview on the bioactive molecules of various amphibian skins has been discussed.

Reconstitution of affinity-purified dopamine D2 receptor binding activities by specific lipids.

The role of lipids in maintaining ligand binding properties of affinity-purified bovine striatal dopamine D2 receptor was investigated in detail. The receptor, purified on a haloperidol-linked Sepharose CL6B affinity column, exhibited low [3H]spiroperidol binding unless reconstituted with soybean phospholipids. In order to understand the role of individual phospholipids in maintaining the receptor binding activity, the purified preparation was reconstituted separately with individual phospholipids and assayed for [3H]spiroperidol binding. Except for phosphatidylcholine and phosphatidylethanolamine, that respectively restored 30 and 20% binding as compared to that obtained with soybean lipids, reconstitution with other lipids had very little effect. When various combinations of phospholipids were used for reconstitution, a phosphatidylcholine and phosphatidylserine mixture seemed to almost fully restore the receptor binding. A mixture of phosphatidylcholine and phosphatidylethanolamine was as effective as phosphatidylcholine alone in reconstituting ligand binding; however, when phosphatidylserine was also included in the mixture, there was a pronounced increase in binding (about 2-fold compared to the soybean lipids and about 6-fold compared to the phosphatidylcholine-phosphatidylethanolamine mixture). Substitution of other phospholipids or cholesterol for phosphatidylserine in phosphatidylcholine and phosphatidylethanolamine mixture had little effect. Maximal reconstitution of [3H]spiroperidol binding was obtained with phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine mixture (2:2:1, w/w) at a concentration of 0.5 mg/ml. The reconstituted receptor exhibited high affinity binding for [3H]spiroperidol which was comparable to that obtained with membrane or solubilized preparations. Various dopaminergic antagonists and agonists showed appropriate order of potency for the reconstituted receptor. The presently described reconstitution data suggest a role of specific phospholipids in preserving the binding properties of dopamine D2 receptor and should prove useful in studies on functional reconstitution of the receptor.

Treatment of gingival pigmentation: a case series.

A smile expresses a feeling of joy, success, sensuality, affection and courtesy, and reveals self confidence and kindness. The harmony of the smile is determined not only by the shape, the position and the color of the teeth but also by the gingival tissues. Gingival health and appearance are essential components of an attractive smile. Gingival pigmentation results from melanin granules, which are produced by melanoblasts. The degree of pigmentation depends on melanoblastic activity. Although melanin pigmentation of the gingiva is completely benign and does not present a medical problem, complaints of 'black gums' are common particularly in patients having a very high smile line (gummy smile). For depigmentation of gingiva different treatment modalities have been reported like- Bur abrasion, scraping, partial thickness flap, cryotherapy, electrosurgery and laser. In the present case series bur abrasion, scraping, partial thickness flap (epithelial excision) cryotherapy and electrosurgery have been tried for depigmentation, which are simple, effective and yield good results, along with good patient satisfaction. The problems encountered with some of these techniques have also been discussed.

Catecholamine-sensitive adenylate cyclase in frontal cortex of primate brain.

Adenylate cyclase activity (AC) of homogenates of monkey frontal cortex was stimulated by catecholamines (dopamine, norepinephrine and isoproterenol), apomorphine, clonidine, NaF and GPP(NH)P. The increment in activity due to dopamine was enhanced in the presence of GPP(NH)P. The AC was also stimulated by 0.2-0.4 mM Ca2+ in the presence of 0.2 mM EGTA; at 0.8 mM Ca2+ had little or no influence on basal or NaF-stimulated activity. However, as Ca2+ concentration was increased from 0.2 to 0.8 mM stimulation by dopamine or GPP(NH)P was progressively inhibited. These results suggest a possible function of Ca2+ in modulating neurotransmitter stimulation of AC in the monkey frontal cortex. The AC exhibited higher sensitivity to dopamine than to norepinephrine or isoproterenol; however dopamine and norepinephrine caused the same maximum stimulation of the enzyme, a stimulation womewhat greater than that produced by isoproterenol. An additivity in stimulating AC was observed for dopamine and isoproterenol but not for dopamine and norepinephrine. Norepinephrine- or dopamine-stimulated AC was effectively blocked by fluphenazine and other dopamine-receptor blocking agents (relative potency for blockade; fluphenazine, haloperidol greater than clozapine, thioridazine greater than pimozide) but not by propranolol, a beta-receptor blocker. In contrast, isoproterenol-stimulated AC was antagonized by propranolol or alprenolol but not by fluphenazine. On the basis of these results, at least two distinct receptors appear to be associated with AC of monkey frontal cortex: (1) a beta-receptor stimulated by isoproterenol and (2) a new type of dopamine or dopamine-norepinephrine receptor, stimulated by either dopamine or norepinephrine. This latter system differs from more typical dopamine receptors found in caudate, retina and limbic cortex in that (a) it is not stimulated by 1-(3,4-dihydroxybenzyl)-4-(2-pyrimidinyl) piperazine (S584); (b) it is stimulated significantly by the putative alpha-receptor agonist, clonidine; (c) it is more sensitive to blockade by clozapine than primate retina or caudate; also the sensitivity to haloperidol is greater than has been reported for non-primate caudate; (d) it is very sensitive to stimulation by norepinephrine and to blockade by phentolamine (an alpha-receptor blocker).

Brain adenylate cyclase activity in the amphetamine sensitized rat.

Behaviour was augmented in rats by treatment with 10 mg/kgm d-amphetamine twice a day for 10 days. A greater activation of adenylate cyclase was found in dopamine rich areas of these rats brains than in normal controls when the enzyme was tested with sodium fluoride and quanylimidodiphosphate. These results parallel similar findings in the brains of schizophrenics obtained at post mortem and support the use of amphetamine sensitization in rats as a model for schizophrenia.

Tumour thickness and relationship to locoregional failure in cancer of the buccal mucosa.

AIMS: The TNM system is the main parameter in treatment planning and the prediction of survival in oral cancer. Here, we investigate the role of tumour thickness as a predictor of locoregional failure and survival in node-negative patients. METHODS: We studied 176 node-negative and early stage gingivo-buccal squamous cell carcinoma patients retrospectively. Clinico-pathological factors investigated for tumour failure prediction were: T stage; tumour differentiation; tumour thickness; and treatment. Tumour thickness was measured using an ocular micrometer. RESULTS: Locoregional tumour failure was found in 34% of cases (60 of 176). Tumour differentiation was found not to be statistically significant in predicting tumour failure. The covariates predicting tumour failure were T stage (P<0.05); type of surgical treatment (P<0.05); and tumour thickness (P<0.001). The mean tumour thickness found was 4 mm. Tumours 4 mm in thickness behaved similarly in all three stages and those >4 mm had a higher rate of lymph-node metastasis. No distant metastasis was found in this series. CONCLUSION: Tumour thickness was found to be an accurate predictor of locoregional failure in early stage cancer of the buccal mucosa.

Preliminary results from an indoor radon thoron survey in Hungary.

More than half of the radiation dose of natural origin comes from radon. However, according to some surveys in certain cases, the radiation dose originating from thoron may be considerable. Among the factors disturbing the measurement of radon, the presence of thoron may also influence the measured radon value, making the estimated radiation exposure imprecise. Thoron has previously been surveyed, mainly in Asia; however, recent surveys for some European locations have found that significant thoron concentrations also need to be considered. In this survey, several types of commercially available SSNTDs (solid-state nuclear track detectors) capable of measuring both radon and thoron were placed at the same time in 73 houses and 7 workplaces in Hungary with 3-month exposition periods. In order to measure thoron, the distance of the detector sets was fixed as 15-20 cm from the walls. The radon concentration was measured with five types of SSNTDs: NRPB, NRPB SSI, Raduet, DTPS and DRPS. The first four types had relatively good accordance (within ± 10 %), but the results of the DRPS detectors were considerably lower when compared with other detectors for radon concentrations over 100 Bq m(-3). The thoron averages were provided by two different types of detectors: Raduet and DTPS. The difference between their average results was more than 30 % and was six times the maximum values. Therefore, the thoron measurement results were judged to be erroneous, and their measurement protocol should be clearly established for future work.

Field experience on indoor radon, thoron and their progenies with solid-state detectors in a survey of Kosovo and Metohija (Balkan region).

Since 1996/97, indoor radon has been measured in scattered locations around Kosovo. In the most recent campaign, apart from radon, thoron and Rn and Tn progenies have also been measured. The current survey involves 48 houses, in which different detectors have been deployed side-by-side in one room, in order to measure indoor radon and thoron gas with RADUET devices based on CR-39 detectors (analysed by Japanese collaborators) and with direct thoron and radon progeny sensor (DTPS and DRPS) devices based on LR-115 detectors (analysed by collaborators from India). Estimated arithmetic mean values of concentrations in 48 houses are 122 Bq m(-3) for radon and 136 Bq m(-3) for thoron. Those for equilibrium equivalent radon concentration and equilibrium equivalent thoron concentration based on measurements in 48 houses are 40 and 2.1 Bq m(-3), respectively. The arithmetic mean value of the equilibrium factor is estimated to be 0.50 ± 0.23 for radon and 0.037 ± 0.041 for thoron. The preliminary results of these measurements are reported, particularly regarding DTPS and DRPS being set up in real field conditions for the first time in the Balkan region. The results are to be understood under the caveat of open questions related to measurement protocols which yield reproducible and representative results, and to quality assurance of Tn and Rn/Tn progeny measurements in general, some of which are discussed.

Preparation and characterization of amidated pectin based hydrogels for drug delivery system.

In the current studies attempts were made to prepare hydrogels by chemical modification of pectin with ethanolamine (EA) in different proportions. Chemically modified pectin products were crosslinked with glutaraldehyde reagent for preparing hydrogels. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), organic elemental analysis, X-ray diffraction studies (XRD), swelling studies, biocompatibility and hemocompatibility studies. Mechanical properties of the prepared hydrogels were evaluated by tensile test. The hydrogels were loaded with salicylic acid (used as a model drug) and drug release studies were done in a modified Franz's diffusion cell. FTIR spectroscopy indicated the presence of primary and secondary amide absorption bands. XRD studies indicated increase in crystallinity in the hydrogels as compared to unmodified pectin. The degree of amidation (DA) and molar and mass reaction yields (YM and YN) was calculated based on the results of organic elemental analysis. The hydrogels showed good water holding properties and were found to be compatible with B-16 melanoma cells & human blood.

Reconstruction of alae of the nose and angle of the mouth with naso labial flap.

Naso labial flap is an ideal flap for reconstruction of alae of the nose and angle of the mouth after excision for malignancy. Due to inconspicuous deformity of the donor area it is ideal in old age. We report our experience in 7 cases of basal cell carcinoma of the alae of the nose and 11 cases of carcinoma angle of the mouth.

Pectoralis major rib osteomyo cutaneous flap in primary mandibular reconstruction in floor of the mouth cancer.

We report pectoralis major rib osteo myocutaneous flap in reconstruction of cancer floor of the mouth in 8 cases. We have discussed it's advantages in country like ours over the micro vascular graft. The rib (Vascularised bone graft) incorporated in this flap gives ideal support for mandibular arch reconstruction.

Xylanases of marine fungi of potential use for biobleaching of paper pulp.

Microbial xylanases that are thermostable, active at alkaline pH and cellulase-free are generally preferred for biobleaching of paper pulp. We screened obligate and facultative marine fungi for xylanase activity with these desirable traits. Several fungal isolates obtained from marine habitats showed alkaline xylanase activity. The crude enzyme from NIOCC isolate 3 (Aspergillus niger), with high xylanase activity, cellulase-free and unique properties containing 580 U l(-1) xylanase, could bring about bleaching of sugarcane bagasse pulp by a 60 min treatment at 55 degrees C, resulting in a decrease of ten kappa numbers and a 30% reduction in consumption of chlorine during bleaching. The culture filtrate showed peaks of xylanase activity at pH 3.5 and pH 8.5. When assayed at pH 3.5, optimum activity was detected at 50 degrees C, with a second peak of activity at 90 degrees C. When assayed at pH 8.5, optimum activity was seen at 80 degrees C. The crude enzyme was thermostable at 55 degrees C for at least 4 h and retained about 60% activity. Gel filtration of the 50-80% ammonium sulphate-precipitated fraction of the crude culture filtrate separated into two peaks of xylanase with specific activities of 393 and 2,457 U (mg protein)(-1). The two peaks showing xylanase activity had molecular masses of 13 and 18 kDa. Zymogram analysis of xylanase of crude culture filtrate as well as the 50-80% ammonium sulphate-precipitated fraction showed two distinct xylanase activity bands on native PAGE. The crude culture filtrate also showed moderate activities of beta-xylosidase and alpha- l-arabinofuranosidase, which could act synergistically with xylanase in attacking xylan. This is the first report showing the potential application of crude culture filtrate of a marine fungal isolate possessing thermostable, cellulase-free alkaline xylanase activity in biobleaching of paper pulp.

Fusion of phosphatidylcholine liposomes induced by polyethylene glycol.

Fusion of small unilamellar vesicles of L-alpha-phosphatidylcholihne (PC) was carried out in the presence of polyethylene glycol (PEG, Mr 6000-7500). The fusion of liposomes was detected by (i) monitoring the efficiency of energy transfer from chlorophyll b (Chl b) to chlorophyll a (Chl a), (ii) formation of fluorescent complex Tb (DPA)3(3-) between terbium chloride (TbCl3) and dipicolinic acid (DPA), (iii) light scattering at 520 nm and (iv) PMR spectroscopy. The changes in the proton magnetic resonance (PMR) signal intensities and increase in the linewidths of the fatty acyl chain methylenes and terminal methyl group in presence of PEG are discussed in relation to fusion.

Solubilization and reconstitution of dopamine D1 receptor from bovine striatal membranes: effects of agonist and antagonist pretreatment.

The bovine striatal dopamine D1 receptor was solubilized with a combination of sodium cholate and NaCl in the presence of phospholipids, following treatment of membranes with a dopaminergic agonist (SKF-82526-J) or antagonist (SCH-23390). The solubilized receptors were subsequently reconstituted into lipid vesicles by gel-filtration. A comparison of ligand-binding properties shows that the solubilized and reconstituted receptors bound [3H]SCH-23390 to a homogeneous site in a saturable, stereospecific and reversible manner with a Kd of 0.95 and 1.1 nM and a Bmax of 918 and 885 fmol/mg protein respectively for agonist- and antagonist-pretreated preparations. These values are very similar to those obtained for membrane-bound receptors. The competition of antagonists for [3H]SCH-23390 binding exhibited a clear D1 dopaminergic order in the reconstituted preparation obtained from either agonist or antagonist-pretreated membranes, except that (+)butaclamol was about four-fold more potent than cis-flupentixol in displacing [3H]SCH-23390 binding in preparation obtained from agonist-pretreated membranes compared to antagonist-pretreated membranes. The agonist/[3H]SCH-23390 competition studies revealed the presence of a high-affinity component of agonist binding in both the reconstituted receptor preparations. The number of high-affinity agonist binding sites, however, is 40-80% higher in reconstituted preparation obtained from antagonist-treated membrane compared to that obtained from the agonist-treated membrane. In both the preparations, 100 microM guanylylimidodiphosphate (Gpp(NH)p) completely abolished the high-affinity component of agonist binding compared to partial abolition in the native membranes, indicating a close association of a G-protein with the solubilized receptors. Whether the receptor was solubilized following agonist or antagonist preincubation of the membranes, the receptor-detergent complex eluted from a steric-exclusion HPLC column with an apparent molecular size of 360,000. Preincubation of the solubilized preparations with Gpp(NH)p had virtually no effect on the elution profile suggesting a lack of guanine nucleotide-dependent dissociation of G-protein receptor complex.