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author:("padmanabha, S")
1.  Efficient Soluble Expression of Active Recombinant Human Cyclin A2 Mediated by E. coli Molecular Chaperones 
Bacterial expression of human proteins continues to present a critical challenge in protein crystallography and drug design. While human cyclin A constructs have been extensively characterized in complex with cyclin dependent kinase 2 (CDK2), efforts to express the monomeric human cyclin A2 in Escherichia coli in a stable form, without the kinase subunit, have been laden with technical difficulties, including solubility, yield and purity. Here, optimized conditions are described with the aim of generating for first time, sufficient quantities of human recombinant cyclin A2 in a soluble and active form for crystallization and ligand characterization purposes. The studies involve implementation of a His-tagged heterologous expression system under conditions of auto-induction and mediated by molecular chaperone-expressing plasmids. A high yield of human cyclin A2 was obtained in natively folded and soluble form, through co-expression with groups of molecular chaperones from E. coli in various combinations. A one-step affinity chromatography method was utilized to purify the fusion protein products to homogeneity, and the biological activity confirmed through ligand-binding affinity to inhibitory peptides, representing alternatives for the key determinants of the CDK2 substrate recruitment site on the cyclin regulatory subunit. As a whole, obtaining the active cyclin A without the CDK partner (referred as monomeric in this work) in a straightforward and facile manner will obviate protein –production issues with the CDK2/cyclin A complex and enable drug discovery efforts for non-ATP competitive CDK inhibition through the cyclin groove.
PMCID: PMC4456239  PMID: 25956535
Recombinant human cyclin A2; Molecular chaperones; Soluble expression; Protein-ligand binding affinity; Tryptophan fluorescence titration
2.  Effect of chitosan-ethylenediamine tetraacetic acid on Enterococcus faecalis dentinal biofilm and smear layer removal 
The objective of the study was to evaluate the effectiveness of chitosan and chitosan-ethylenediamine tetraacetic acid (EDTA) (3:1,1:1,1:3) in comparison with 5.2% sodium hypochlorite (NaOCl) in disinfecting Enterococcus faecalis biofilm on root canal dentin and in the removal of smear layer with minimal erosion.
Materials and Methods:
Seventy single-rooted extracted human mandibular premolars (n = 70) were selected for the study. Forty tooth samples were biomechanically prepared, vertically sectioned, and sterilized by autoclaving. The tooth sections were artificially infected with E. faecalis (ATCC 29212 [n = 35] and clinical isolate [SBEF2, n = 35]) to form mature dentinal biofilm in vitro. The tooth samples were treated with the test solutions: chitosan and chitosan-EDTA (3:1, 1:1, 1:3), and the killing time was determined. The smear layer removal ability of the test solutions (Group A: chitosan-EDTA [1:1], Group B: EDTA, Group C: control) (n = 10 tooth/group) was assessed.
Chitosan and chitosan-EDTA (3:1, 1:1, 1:3) exhibited antibacterial activity against both the strains of E. faecalis. Chitosan and chitosan-EDTA caused 3 log reduction in the viable count of the sessile cells of E. faecalis at 15 min while 5.2% NaOCl exhibited 99.98% inhibition at 15 min. Chitosan-EDTA (1:1) was found to be effective in removing the smear layer and showed lesser erosion than EDTA at the coronal and middle portions.
Chitosan-EDTA (1:1) is a potential root canal irrigant that performs a dual role – root canal disinfection and smear layer removal.
PMCID: PMC5026111  PMID: 27656070
Chitosan; chitosan-ethylenediamine tetraacetic acid; dentinal biofilm; Enterococcus faecalis; ethylenediamine tetraacetic acid
3.  Contrast-enhanced fluorodeoxyglucose positron emission tomography/computed tomography in solid pseudopapillary neoplasm of the pancreas 
Solid pseudopapillary neoplasm (SPN) of the pancreas is a rare pancreatic tumor with low malignant potential. It occurs characteristically more often in young women. Radiological and pathological studies have revealed that the tumor is quite different from other pancreatic tumors. Limited information is available in the literature reporting their accumulation of fluorine-18 fluorodeoxyglucose (18F-FDG) in positron emission tomography/computed tomography (PET/CT). Here, we report a case of pancreatic SPN imaged with contrast-enhanced FDG PET/CT. A percutaneous fine needle aspiration from the metabolically active lesion revealed SPN, and it was confirmed with histopathological results. Recurrence or metastasis was not found after 7 months of follow-up.
PMCID: PMC4815386  PMID: 27095862
Fluorodeoxyglucose positron emission tomography/computed tomography; pancreatectomy; percutaneous biopsy; solid pseudopapillary neoplasm; solid pseudopapillary neoplasm of pancreas
4.  Persistent post-stroke dysphagia treated with cricopharyngeal myotomy 
Post-stroke dysphagia is a common problem after stroke. About 8-13% patients have persistent dysphagia and are unable to return to pre-stroke diet even after 6 months of stroke. Use of percutaneous endoscopic gastrostomy (PEG) may be required in these patients, which may be psychologically unacceptable and impair the quality of life. In those with cricopharyngeal dysfunction leading on to refractory post-stroke dysphagia, cricopharyngeal myotomy and injection of botulinum toxin are the treatment options. We present a case of vertebrobasilar stroke who had persistent dysphagia due to cricopharyngeal dysfunction with good recovery of swallowing function following cricopharyngeal myotomy 1.5 years after the stroke.
PMCID: PMC4888691  PMID: 27293339
Cricopharyngealmyotomy; post-stroke dysphagia; videofluoroscopy
5.  Multidrug Resistant CTX-M-Producing Escherichia coli: A Growing Threat among HIV Patients in India 
Journal of Pathogens  2016;2016:4152704.
Extended Spectrum β-Lactamases (ESBLs) confer resistance to third-generation cephalosporins and CTX-M types have emerged as the most prominent ESBLs worldwide. This study was designed to determine the prevalence of CTX-M positive ESBL-producing urinary E. coli isolates from HIV patients and to establish the association of multidrug resistance, phylogeny, and virulence profile with CTX-M production. A total of 57 ESBL producers identified among 76 E. coli strains isolated from HIV patients from South India were screened for blaCTX-M, AmpC production, multidrug resistance, and nine virulence associated genes (VAGs), fimH, pap, afa/dra, sfa/foc, iutA, fyuA, iroN, usp, and kpsMII. The majority (70.2%) of the ESBL producers harbored blaCTX-M and were AmpC coproducers. Among the CTX-M producers, 47.5% were found to be UPEC, 10% harbored as many as 7 VAGs, and 45% possessed kpsMII. Multidrug resistance (CIPRSXTRGENR) was significantly more common among the CTX-M producers compared to the nonproducers (70% versus 41.2%). However, 71.4% of the multidrug resistant CTX-M producers exhibited susceptibility to nitrofurantoin thereby making it an effective alternative to cephalosporins/fluoroquinolones. The emergence of CTX-M-producing highly virulent, multidrug resistant uropathogenic E. coli is of significant public health concern in countries like India with a high burden of HIV/AIDS.
PMCID: PMC4829713  PMID: 27123344
6.  Annular elastolytic giant cell granuloma in association with Hashimoto's thyroiditis 
Annular elastolytic giant cell granuloma (AEGCG) is a rare granulomatous skin disease characterized clinically by annular plaques with elevated borders and atrophic centers found mainly on sun-exposed skin and histologically by diffuse granulomatous infiltrates composed of multinucleated giant cells, histiocytes and lymphocytes in the dermis along with phagocytosis of elastic fibers by multinucleated giant cells. We report a case of AEGCG in a 50-year-old woman and is highlighted for the classical clinical and histological findings of the disease and its rare co-existence with Hashimoto's thyroiditis.
PMCID: PMC4804578  PMID: 27057492
Annular elastolytic giant cell granuloma; Hashimoto's thyroiditis; mid-dermal elastolysis
7.  Cell Migration on Planar and Three-Dimensional Matrices: A Hydrogel-Based Perspective 
The migration of cells is a complex process that is dependent on the properties of the surrounding environment. In vivo, the extracellular environment is complex with a wide range of physical features, topographies, and protein compositions. There have been a number of approaches to design substrates that can recapitulate the complex architecture in vivo. Two-dimensional (2D) substrates have been widely used to study the effect of material properties on cell migration. However, such substrates do not capture the intricate structure of the extracellular environment. Recent advances in hydrogel assembly and patterning techniques have enabled the design of new three-dimensional (3D) scaffolds and microenvironments. Investigations conducted on these matrices provide growing evidence that several established migratory trends obtained from studies on 2D substrates could be significantly different when conducted in a 3D environment. Since cell migration is closely linked to a wide range of physiological functions, there is a critical need to examine migratory trends on 3D matrices. In this review, our goal is to highlight recent experimental studies on cell migration within engineered 3D hydrogel environments and how they differ from planar substrates. We provide a detailed examination of the changes in cellular characteristics such as morphology, speed, directionality, and protein expression in 3D hydrogel environments. This growing field of research will have a significant impact on tissue engineering, regenerative medicine, and in the design of biomaterials.
PMCID: PMC4321976  PMID: 25011932
8.  Iterative Conversion of Cyclin Binding Groove Peptides into Druglike CDK Inhibitors with Antitumor Activity 
Journal of Medicinal Chemistry  2014;58(1):433-442.
The cyclin groove is an important recognition site for substrates of the cell cycle cyclin dependent kinases and provides an opportunity for highly selective inhibition of kinase activity through a non-ATP competitive mechanism. The key peptide residues of the cyclin binding motif have been studied in order to precisely define the structure–activity relationship for CDK kinase inhibition. Through this information, new insights into the interactions of peptide CDK inhibitors with key subsites of the cyclin binding groove provide for the replacement of binding determinants with more druglike functionality through REPLACE, a strategy for the iterative conversion of peptidic blockers of protein–protein interactions into pharmaceutically relevant compounds. As a result, REPLACE is further exemplified in combining optimized peptidic sequences with effective N-terminal capping groups to generate more stable compounds possessing antitumor activity consistent with on-target inhibition of cell cycle CDKs. The compounds described here represent prototypes for a next generation of kinase therapeutics with high efficacy and kinome selectivity, thus avoiding problems observed with first generation CDK inhibitors.
PMCID: PMC4334226  PMID: 25454794
9.  Gastric cancer risk in relation to tobacco use and alcohol drinking in Kerala, India - Karunagappally cohort study 
World Journal of Gastroenterology  2015;21(44):12676-12685.
AIM: To assess the risk of gastric cancer (GC) in relation to tobacco use and alcohol drinking in the Karunagappally cohort in Kerala, South India.
METHODS: This study examined the association of tobacco use and alcohol drinking with GC incidence among 65553 men aged 30-84 in the Karunagappally cohort. During the period from 1990-2009, 116 GC cases in the cohort were identified as incident cancers. These cases were identified from the population-based cancer registry. Information regarding risk factors such as socioeconomic factors and tobacco and alcohol habits of cohort members were collected from the database of the baseline survey conducted during 1990-1997. The relative risks (RRs) and the corresponding 95% confidence intervals (95%CIs) for tobacco use were obtained from Poisson regression analysis of grouped survival data, considering age, follow-up period, occupation and education.
RESULTS: Bidi smoking was associated with GC risk (P = 0.042). The RR comparing current versus never smokers was 1.6 (95%CI: 1.0-2.5). GC risk was associated with the number of bidis smoked daily (P = 0.012) and with the duration of bidi smoking (P = 0.036). Those who started bidi smoking at younger ages were at an elevated GC risk; the RRs for those starting bidi smoking under the age of 18 and ages 18-22 were 2.0 (95%CI: 1.0-3.9) and 1.8 (95%CI: 1.1-2.9), respectively, when their risks were compared with lifetime non-smokers of bidis. Bidi smoking increased the risk of GC among never cigarette smokers more evidently (RR = 2.2; 95%CI: 1.3-4.0). GC risk increased with the cumulative amount of bidi smoking, which was calculated as the number of bidis smoked per day x years of smoking (bidi-year; P = 0.017). Cigarette smoking, tobacco chewing or alcohol drinking was not significantly associated with GC risk.
CONCLUSION: Among a male cohort in South India, gastric cancer risk increased with the number and duration of bidi smoking.
PMCID: PMC4658623  PMID: 26640345
Bidi smoking; Alcohol drinking; Gastric cancer; The Karunagappally cohort; Kerala; India
10.  An Uncommon Disease at an Unusual Site in a Female Child 
PMCID: PMC4681239  PMID: 26677313
11.  Clinico-Microbiological Investigation of Catheter Associated Urinary Tract Infection by Enterococcus faecalis: vanA Genotype 
Prolonged hospitalization and exposure to third generation cephalosporins are reported to facilitate the acquisition and colonization of Vancomycin Resistant Enterococci (VRE). Though VRE is not uncommon in India, urinary tract infection with a vanA genotype is a cause of serious concern as VRE co-exhibit resistance to aminoglycosides. In India, majority of the VRE isolates recovered from hospitalized patients include Enterococcus faecium. We report a case of catheter associated urinary tract infection by an endogenous, multidrug resistant E. faecalis of vanA genotype following prolonged hospitalization, ICU stay, catheterisation and exposure to 3G cephalosporin and metronidazole. The patient responded to linezolid therapy.
PMCID: PMC4576540  PMID: 26435949
High level aminoglycoside resistance (HLAR); Multidrug resistance; Vancomycin resistant Enterococci (VRE)
12.  Punctate Porokeratosis Palmaris et Plantaris 
Indian Journal of Dermatology  2015;60(3):284-286.
Porokeratosis, a keratinization disorder, is probably a group of unrelated conditions with same distinctive histological appearance, featuring cornoid lamellae. A case of punctate porkeratosis in a 24 year old male patient is reported for its rarity.
PMCID: PMC4458942  PMID: 26120157
Cornoid lamella; keratinization disorder; porokeratosis
13.  Estimation of External Dose by Car-Borne Survey in Kerala, India 
PLoS ONE  2015;10(4):e0124433.
A car-borne survey was carried out in Kerala, India to estimate external dose. Measurements were made with a 3-in × 3-in NaI(Tl) scintillation spectrometer from September 23 to 27, 2013. The routes were selected from 12 Panchayats in Karunagappally Taluk which were classified into high level, mid-level and low level high background radiation (HBR) areas. A heterogeneous distribution of air kerma rates was seen in the dose rate distribution map. The maximum air kerma rate, 2.1 μGy/h, was observed on a beach sand surface. 232Th activity concentration for the beach sand was higher than that for soil and grass surfaces, and the range of activity concentration was estimated to be 0.7–2.3 kBq/kg. The contribution of 232Th to air kerma rate was over 70% at the measurement points with values larger than 0.34 μGy/h. The maximum value of the annual effective dose in Karunagappally Taluk was observed around coastal areas, and it was estimated to be 13 mSv/y. More than 30% of all the annual effective doses obtained in this survey exceeded 1 mSv/y.
PMCID: PMC4401755  PMID: 25885680
14.  Orthodontic instrument sterilization with microwave irradiation 
Journal of Pharmacy & Bioallied Sciences  2015;7(Suppl 1):S111-S115.
This study was designed to evaluate the efficiency of microwave sterilization of orthodontic instruments and molar bands immersed in plain distilled water with and without oral rinse, and to ascertain the minimum time of exposure required to sterilize.
Materials and Methods:
The orthodontic instruments (hinged and nonhinged), molar bands and mouth mirrorsused in the patient 's mouth were selected for the study. The instruments were divided into two groups – Group I with oral rinse-set A (0.01% chlorhexidine gluconate) and set B (0.025% betadine) and Group II (included sets C and D without oral rinse). The instruments of set A, B and C were microwaved at 2,450 MHz, 800 W for 5 min, whereas, set D was microwaved for 10 min at the same above mentioned specifications. The efficacy of sterilization was assessed by stab inoculation of the instruments onto trypticase soya agar plates. The plates were checked for bacterial growth following incubation at 37 °C for 24 h. For sterility control,Geobacillus stearothermophilus (MTCC 1518) was included.
No growth was observed in the plates that were inoculated with the microwaved orthodontic instruments of sets A, B and D, whereas scanty bacterial growth was observed in the plates inoculatedwith the microwaved set C instruments.
Effective sterilization was achieved when the orthodontic instruments and molar bands were immersed in distilled water without oral rinse and microwaved for 10 min as also for those that were immersed in distilled water with oral rinse and microwaved for 5 min.
PMCID: PMC4439646  PMID: 26015686
Biological indicator; microwave sterilization; molar bands; orthodontic pliers
15.  Fragment based discovery of Arginine isosteres through REPLACE: towards non-ATP competitive CDK inhibitors 
Bioorganic & medicinal chemistry  2013;22(1):616-622.
In order to develop non-ATP competitive CDK2/cyclin A inhibitors, the REPLACE strategy has been applied to generate fragment alternatives for the N-terminal tetrapeptide of the cyclin binding motif (HAKRRLIF) involved in substrate recruitment prior to phosphotransfer. The docking approach used for the prediction of small molecule mimics for peptide determinants was validated through reproduction of experimental binding modes of known inhibitors and provides useful information for evaluating binding to protein-protein interaction sites. Further to this, potential arginine isosteres predicted using the validated LigandFit docking method were ligated to the truncated C-terminal peptide, RLIF using solid phase synthesis and evaluated in a competitive binding assay. After testing, identified fragments were shown to represent not only appropriate mimics for a critical arginine residue but also to interact effectively with a minor hydrophobic pocket present in the binding groove. Further evaluation of binding modes was undertaken to optimize the potency of these compounds. Through further application of the REPLACE strategy in this study, peptide-small molecule hybrid CDK2 inhibitors were identified that are more drug-like and suitable for further optimization as anti-tumor therapeutics.
PMCID: PMC3917480  PMID: 24286762
16.  Pomegranate Juice Enhances Healthy Lifespan in Drosophila melanogaster: An Exploratory Study 
Exploring innovative ways to ensure healthy aging of populations is a pre-requisite to contain rising healthcare costs. Scientific research into the principles and practices of traditional medicines can provide new insights and simple solutions to lead a healthy life. Rasayana is a dedicated branch of Ayurveda (an Indian medicine) that deals with methods to increase vitality and delay aging through the use of diet, herbal supplements, and other lifestyle practices. The life-span and health-span enhancing actions of the fruits of pomegranate (Punica granatum L.), a well-known Rasayana, were tested on Drosophila melanogaster (fruitfly) model. Supplementation of standard corn meal with 10% (v/v) pomegranate juice (PJ) extended the life-span of male and female flies by 18 and 8%, respectively. When male and female flies were mixed and reared together, there was 19% increase in the longevity of PJ fed flies, as assessed by MSD, the median survival day (24.8). MSD for control and resveratrol (RV) groups was at 20.8 and 23.1 days, respectively. A two-fold enhancement in fecundity, improved resistance to oxidative stress (H2O2 and paraquat induced) and to Candida albicans infection were observed in PJ fed flies. Further, the flies in the PJ fed group were physically active over an extended period of time, as assessed by the climbing assay. PJ thus outperformed both control and RV groups in the life-span and health-span parameters tested. This study provides the scope to explore the potential of PJ as a nutraceutical to improve health span and lifespan in human beings.
PMCID: PMC4267107  PMID: 25566518
pomegranate; anti-aging; rasayana; ayurveda; Drosophila
17.  Bone mineral density and factors influencing it in Asian Indian population with type 2 diabetes mellitus 
To assess bone mineral density (BMD) in type 2 diabetes mellitus (T2DM) patients and its relation, if any, to clinical, hormonal and metabolic factors.
Materials and Methods:
A prospective evaluation of 194 T2DM patients (97 men and 97 women) was carried out. BMD was done with dual energy X-ray absorptiometry (DXA) at the lumbar spine and total hip. Physical activity, nutritional intake and sunlight exposure were calculated. Biochemical and hormonal tests included serum 25 hydroxy vitamin D [25(OH) D], parathyroid hormone, estrogen, testosterone and urinary calcium-creatinine ratio. Glycosylated hemoglobin and complete lipid profiles were done in patients with diabetes. Five hundred and seventy one non-diabetic controls (262 males and 309 females) were evaluated for BMD alone.
BMD was normal (Z score > -2) in 156 (80.5%) and low (Z score ≤ -2) in 38 (19.5%) patients in the diabetes study group. BMD in the diabetes group was significantly higher than the control group in both sexes at the hip and spine. The difference was no longer significant on analysis of a BMI matched control subgroup. Weight and BMI showed significant correlation to BMD. Duration of T2DM, degree of glycemic control, use of drugs like statins and thiazolidinediones, 25(OH) D levels, calcium intake, sunlight exposure and physical activity did not significantly affect BMD in this cohort of individuals with diabetes.
Bone mineral density of Asian Indian T2DM subjects was similar to that of healthy volunteers in this study.
PMCID: PMC4192990  PMID: 25364679
Asian Indian; bone mineral density; obesity; type 2 diabetes mellitus; vitamin D deficiency
19.  Designing a Multicellular Organotypic 3D Liver Model with a Detachable, Nanoscale Polymeric Space of Disse 
Tissue Engineering. Part C, Methods  2013;19(11):875-884.
The design of in vitro models that mimic the stratified multicellular hepatic microenvironment continues to be challenging. Although several in vitro hepatic cultures have been shown to exhibit liver functions, their physiological relevance is limited due to significant deviation from in vivo cellular composition. We report the assembly of a novel three-dimensional (3D) organotypic liver model incorporating three different cell types (hepatocytes, liver sinusoidal endothelial cells, and Kupffer cells) and a polymeric interface that mimics the Space of Disse. The nanoscale interface is detachable, optically transparent, derived from self-assembled polyelectrolyte multilayers, and exhibits a Young's modulus similar to in vivo values for liver tissue. Only the 3D liver models simultaneously maintain hepatic phenotype and elicit proliferation, while achieving cellular ratios found in vivo. The nanoscale detachable polymeric interfaces can be modulated to mimic basement membranes that exhibit a wide range of physical properties. This facile approach offers a versatile new avenue in the assembly of engineered tissues. These results demonstrate the ability of the tri-cellular 3D cultures to serve as an organotypic hepatic model that elicits proliferation and maintenance of phenotype and in vivo-like cellular ratios.
PMCID: PMC3793659  PMID: 23556413
21.  Aggressive Angiomyxoma 
Myxoid tumors are a heterogeneous group of lesions characterized by a marked abundance of extra cellular mucoid (myxoid) matrix.[1] The term aggressive emphasizes the often infiltrative nature of the tumor and its frequent association with recurrence.[2] A case of aggressive angiomyxoma arising from the vagina in a 55-year-old woman is reported for its rarity.
PMCID: PMC4030341  PMID: 24860748
Aggressive; angio myxoma; Carney complex
22.  Optimization of non-ATP competitive CDK/cyclin groove Inhibitors through REPLACE mediated Fragment Assembly 
Journal of medicinal chemistry  2013;56(4):1573-1582.
A major challenge in drug discovery is to develop and improve methods for targeting protein-protein interactions. Further exemplification of the REPLACE strategy for generating inhibitors of protein-protein interactions demonstrated that it can be used to optimize fragment alternatives of key determinants, to combine these in an effective way and was achieved for compounds targeting the CDK2 substrate recruitment site on the cyclin regulatory subunit. Phenylheterocyclic isosteres replacing a critical charge-charge interaction provided new structural insights for binding to the cyclin groove. In particular, these results shed light onto the key contributions of a H-bond observed in crystal structures of N-terminally capped peptides. Furthermore the structure-activity relationship of a bisarylether C-terminal capping group mimicking dipeptide interactions, was probed through ring substitutions, allowing increased complementarity with the primary hydrophobic pocket. This study further validates REPLACE as an effective strategy for converting peptidic compounds to more pharmaceutically relevant compounds.
PMCID: PMC3692612  PMID: 23323521
23.  Impact of Endophytic Microorganisms on Plants, Environment and Humans 
The Scientific World Journal  2014;2014:250693.
Endophytes are microorganisms (bacteria or fungi or actinomycetes) that dwell within robust plant tissues by having a symbiotic association. They are ubiquitously associated with almost all plants studied till date. Some commonly found endophytes are those belonging to the genera Enterobacter sp., Colletotrichum sp., Phomopsis sp., Phyllosticta sp., Cladosporium sp., and so forth. Endophytic population is greatly affected by climatic conditions and location where the host plant grows. They produce a wide range of compounds useful for plants for their growth, protection to environmental conditions, and sustainability, in favour of a good dwelling place within the hosts. They protect plants from herbivory by producing certain compounds which will prevent animals from further grazing on the same plant and sometimes act as biocontrol agents. A large amount of bioactive compounds produced by them not only are useful for plants but also are of economical importance to humans. They serve as antibiotics, drugs or medicines, or the compounds of high relevance in research or as compounds useful to food industry. They are also found to have some important role in nutrient cycling, biodegradation, and bioremediation. In this review, we have tried to comprehend different roles of endophytes in plants and their significance and impacts on man and environment.
PMCID: PMC3920680  PMID: 24587715
24.  Effects of solubilizing surfactants and loading of antiviral, antimicrobial, and antifungal drugs on their release rates from ethylene vinyl acetate copolymer 
This study investigates the effects of surfactants and drug loading on the drug release rate from ethylene vinyl acetate (EVA) copolymer. The release rate of nystatin from EVA was studied with addition of non-ionic surfactants Tween 60 and Cremophor RH 40. In addition, the effect of increasing drug load on the release rates of nystatin, chlorhexidine diacetate and acyclovir is also presented.
Polymer casting solutions were prepared by stirring EVA copolymer and nystatin (2.5 wt %) in dichloromethane. Nystatin and surfactants were added in ratios of (1:1), (1:2) and (1:3). Drug loading was studied with 2.5, 5.0, 7.5, and 10.0% wt. proportions of nystatin, chlorhexidine diacetate and acyclovir incorporated into a separate polymer. Three drug loaded polymer square films (3cm × 3cm × 0.08 cm) were cut from dry films to follow the kinetics of drug release at 37°C. 10 ml of either distilled water or PBS was used as the extracting medium that was replaced daily. PBS was used for nystatin release with addition of surfactants and water was used for the study on drug loading and surfactant release. The rate of drug release was measured by UV-spectrophotometer. The amount of surfactant released was determined by HPLC.
The release of nystatin was low in PBS and its release rate increased with the addition of surfactants. Also, increasing surfactant concentrations resulted in increased drug release rates. The release rates of chlorhexidine diacetate (p<0.0001), acyclovir (p<0.0003) and nystatin (p<0.0017) linearly increased with increasing drug loads. The amount of surfactants released was above the CMC.
This study demonstrates that the three therapeutic agents show a sustained rate of drug release from EVA copolymer over extended periods of time. Nystatin release in PBS is low owing to its poor solubility. Its release rate is enhanced by addition of surfactants and increasing the drug load as well.
PMCID: PMC3881552  PMID: 17049593
Drug delivery; EVA matrix; nystatin; surfactants; chlorhexidine diacetate; acyclovir; drug loading
25.  Metastatic Crohn's disease 
Crohn's disease, first described in 1922, is characterized by segmental granulomatous inflammation of the intestinal tract and frequently involves the cutaneous tissues as well. Cutaneous Crohn's disease (CCD) is synonymous with metastatic Crohn's disease (MSD). A case of CCD, without any gastrointestinal involvement is reported for its rarity.
PMCID: PMC3937486  PMID: 24616854
Cutaneous crohn's disease; metastatic crohn's disease; non caseating granulomas

Results 1-25 (54)