A polymer-based anti-quorum catheter coating to challenge MDR Staphylococcus aureus: in vivo and in vitro approaches.

BACKGROUND: MDR Staphylococcus aureus is a major aetiological agent of catheter-associated infections. A quorum sensing targeted drug development approach proves to be an effective alternative strategy to combat such infections. METHODS: Intravenous catheters were coated with polymethacrylate copolymers loaded with the antivirulent compound 2-[(methylamino)methyl]phenol (2MAMP). The in vitro drug release profile and kinetics were established. The anti-biofilm effect of the coated catheters was tested against clinical isolates of MDR S. aureus. The in vivo studies were carried out using adult male Wistar rats by implanting coated catheters in subcutaneous pockets. Histopathological analysis was done to understand the immunological reactions induced by 2MAMP. RESULTS: A uniform catheter coating of thickness 0.1 mm was achieved with linear sustained release of 2MAMP for 6 h. The coating formulation was cytocompatible. The in vitro and in vivo anti-adherence studies showed reduced bacterial accumulation in coated catheters after 48 h. The histopathological results confirmed that the coated catheter did not bring about any adverse inflammatory response. CONCLUSIONS: The developed anti-quorum-coated catheter that is non-toxic and biocompatible has the potential to be used in other medical devices, thereby preventing catheter-associated infections.

Artesunate obliterates experimental hepatocellular carcinoma in rats through suppression of IL-6-JAK-STAT signalling.

Activation of the IL-6 mediated JAK-STAT (Janus associated kinase-signal transducer and activator of transcription) oncogenic signalling plays a major role in hepatocellular carcinoma pathogenesis. The aim of this study is to assess the anti-tumour, anti-proliferative and apoptotic potential of artesunate and its capacity to modulate JAK-STAT pathway in a nitrosodiethylamine mediated experimental hepatocellular carcinoma model. Administration of nitrosodiethylamine (200mg/kg body weight by i.p. Injections) to rats resulted in alterations of liver pathophysiological parameters such as increased relative liver weight, and increased tumour nodule occurrence. It also increased the levels of serum marker enzymes (AST, ALT, ALP, LDH, and γGT) and tumour biomarker (AFP) levels suggestive of its capacity to cause liver tumourigenesis. Additionally, the immunohistochemistry of liver sections pertaining to nitrosodiethylamine administered animals showed increased detection of AgNOR, PCNA, and GST-Pi positive cells suggestive of its capacity to promote liver proliferation associated tumourigenesis. On the contrary, artesunate (25mg/kg bodyweight) supplementation to nitrosodiethylamine administered animals decreased all the above mentioned pathophysiological, biochemical, and immunohistochemistry parameters suggesting its anti-tumour and anti-proliferative potential. Furthermore, immunoblot analysis showed significant up-regulation of IL-6, GP130, JAK-2, STAT-3 (pY705), Bcl-xL, Bcl-2 and simultaneous down-regulation of Caspase-3, PARP and SOCS-3 in nitrosodiethylamine administered animals. Nevertheless, the immunoblot analysis revealed vice-versa on artesunate supplementation to nitrosodiethylamine administered animals, indicating promotion of the feedback loop inhibition mechanism through SOCS3 up-regulation thereby leading to suppression of JAK-STAT signalling. Overall all these findings substantiate that artesunate promotes anti-tumour, anti-proliferation and apoptosis against nitrosodiethylamine mediated hepatocellular carcinoma.

Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model

Purpose: Sodium thiosulfate (STS) is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. Materials and Methods: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG) along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. Results: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening) treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer) treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. Conclusion: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

Development of a biofilm inhibitor molecule against multidrug resistant Staphylococcus aureus associated with gestational urinary tract infections.

Urinary Tract Infection (UTI) is a globally widespread human infection caused by an infestation of uropathogens. Eventhough, Escherichia coli is often quoted as being the chief among them, Staphylococcus aureus involvement in UTI especially in gestational UTI is often understated. Staphylococcal accessory regulator A (SarA) is a quorum regulator of S. aureus that controls the expression of various virulence and biofilm phenotypes. Since SarA had been a focussed target for antibiofilm agent development, the study aims to develop a potential drug molecule targeting the SarA of S. aureus to combat biofilm associated infections in which it is involved. In our previous studies, we have reported the antibiofilm activity of SarA based biofilm inhibitor, (SarABI) with a 50% minimum biofilm inhibitory concentration (MBIC50) value of 200 µg/mL against S. aureus associated with vascular graft infections and also the antibiofilm activity of the root ethanolic extracts of Melia dubia against uropathogenic E. coli. In the present study, in silico design of a hybrid molecule composed of a molecule screened from M. dubia root ethanolic extracts and a modified SarA based inhibitor (SarABI(M)) was undertaken. SarABI(M) is a modified form of SarABI where the fluorine groups are absent in SarABI(M). Chemical synthesis of the hybrid molecule, 4-(Benzylamino)cyclohexyl 2-hydroxycinnamate (henceforth referred to as UTI Quorum-Quencher, UTI(QQ)) was then performed, followed by in vitro and in vivo validation. The MBIC50 and MBIC90 of UTI(QQ) were found to be 15 and 65 µg/mL, respectively. Confocal laser scanning microscopy (CLSM) images witnessed biofilm reduction and bacterial killing in either UTI(QQ) or in combined use of antibiotic gentamicin and UTI (QQ) . Similar results were observed with in vivo studies of experimental UTI in rat model. So, we propose that the drug UTI(QQ) would be a promising candidate when used alone or, in combination with an antibiotic for staphylococcal associated UTI.

Immunotoxicity assessment of sub-chronic oral administration of acetamiprid in Wistar rats.

CONTEXT: Neonicotinoid insecticides are synthetic analogues of nicotine that acts on the central nervous system of insects by blocking post synaptic acetylcholine receptor. Acetamiprid is one of the widely used neonicotinoid class of insecticide used to control sucking insects like aphids, bees, mosquitoes, on crops. Data on the possible immunotoxic nature of acetamiprid are lacking. OBJECTIVE: The present study was conducted in Wistar rats with the objective of evaluating the immunotoxic potential of acetamiprid administered orally at the dose levels of 27.5, 55 and 110 mg/kg b.w. (equivalent to 5.5, 11 and 22 mg/kg b.w.) for a period of 90 days. MATERIALS AND METHODS: In experiment 1, general toxicity testing including the evaluation of clinical signs, hemato-biochemical changes, response of the lymphocytes towards T and B cell mitogens, macrophage function, gross and histopathology of the lymphoid organs (spleen, thymus, lymph nodes, etc.) were performed. In the second experiment, humoral and cell-mediated responses during immunological challenges were evaluated. RESULTS: Significant decreases were observed in the stimulation index of lymphocyte proliferation to B cell mitogen and in the nitrite production of macrophages of rats treated with 110 mg/kg of acetamiprid. Significant decrease in the lymphoproliferative response towards the B cell mitogen indicated the inability of the B lymphocytes to respond on stimulation that might increase the chances of susceptibility to infections. Acetamiprid also caused 15-28% reduction in nitrite production, an important signal for efficient inflammatory response of macrophages. The functional impairment of macrophages may involve aberrations in the enzymatic degradation of microbes, oxidative burst, generation of free radicals, phagocytosis, release of proinflammatory cytokines and thereby, may hamper host defence causing susceptibility to diseases. No significant changes over hematology, biochemistry, organ weights, histopathology of major immune organs, delayed type hypersensitivity test, response to sRBCs and lymphoproliferation assay for T cell mitogen were observed. CONCLUSION: In conclusion, the results demonstrate for the first time that the subchronic administration of acetamiprid (20% SP-soluble powder) cause significant decreases in the lymphocyte proliferation as well as the macrophage function at the dose level of 110 mg/kg. Considering the chronic population adjusted dose (0.023 mg/kg/day) through dietary exposure for acetamiprid, judicious use of acetamiprid is highly essential. Indiscriminate use of acetamiprid exceeding the doses advised might pose a hazard.

Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model.

PURPOSE: Sodium thiosulfate (STS) is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. MATERIALS AND METHODS: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG) along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. RESULTS: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening) treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer) treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. CONCLUSION: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

Prenatal developmental toxicity evaluation of Withania somnifera root extract in Wistar rats.

CONTEXT: Withania somnifera (L) Dunal (Solanaceae) is an important traditional herbal medicine used for thousands of years and is considered as the Indian ginseng. Reports on the effect of Withania somnifera root (WSR) extract on the developing foetus of pregnant rats including mortality, structural abnormalities, changes in growth and effects on dams are not available. OBJECTIVE: The present study was performed to evaluate the prenatal developmental toxicity potential of WSR extract in rats. MATERIALS AND METHODS: WSR extract was given orally to pregnant rats during the period of major organogenesis and histogenesis (days 5 to 19 of gestation) at the dose levels of 500, 1000 and 2000 mg/kg/day. Clinical observations including mortality, moribundity, behavioural changes, signs of overt toxicity, body weight, gross pathological changes of dams and foetal analyses including external malformations, skeletal and soft tissue malformations were evaluated. RESULTS: No evidence of maternal or foetal toxicity was observed. WSR extract caused no changes (p < 0.05) in body weight of parental females, number of corpora lutea, implantations, viable foetuses, external, skeletal and visceral malformations. DISCUSSION AND CONCLUSION: Under the conditions of the study, the no-observed-effect level (NOEL) of WSR extract for maternal and developmental toxicity was concluded to be at least 2000 mg/kg/day.

Formylchromone exhibits salubrious effects against nitrosodiethylamine mediated early hepatocellular carcinogenesis in rats.

The salubrious effects of 3-Formylchromone (3-FC) against nitrosodiethylamine (NDEA) mediated early hepatocellular carcinogenesis was investigated in vivo by this study. Male Wistar rats were administered three interspersed intraperitoneal injections of NDEA (200 mg/kg body weight) until sixth week, followed by, thrice a week oral dose of 3-FC (25 mg/kg body weight) from the seventh week to eleventh week. Oral supplementation of Wistar rats with 3-FC prevented the increase in serum marker enzymes (AST, ALT, LDH) and serum pre-neoplastic marker (γ-GT) induced by NDEA. Biochemical observations were found to be further correlated with histological studies, indicating the potential of 3-FC to mediate suppression of hepatic damage/pre-neoplastic lesions. Argyrophilic nucleolar organizer region (AgNOR) staining was done in histology sections to confirm the anti-proliferative potential of 3-FC against NDEA-induced early hepatocellular carcinogenesis. RT-PCR and immunoblot analysis was done to find the modulations in the gene transcript/protein level expression of pre-neoplastic marker (GST-pi), proliferation marker (PCNA), apoptotic mediators (PPARγ, NFκB-p65 and p53). 3-FC was found to favorably modulate the expressions of GST-pi, PCNA, PPARγ, NFκB-p65, p53 clearly confirming the anti-proliferative and apoptotic potential of 3-FC. Further, the apoptotic effect of 3-FC against NDEA-induced early hepatocellular carcinogenesis was confirmed by caspase-3 activity assay and DNA fragmentation analysis. Based on these findings, it is concluded that 3-FC possesses hepatoprotective, anti-pre-neoplastic, anti-proliferative and apoptosis inducing capability against NDEA-induced early hepatocellular carcinogenesis.

Acute and sub-acute oral toxicity assessment of the hydroalcoholic extract of Withania somnifera roots in Wistar rats.

Withania somnifera is a widely used medicinal plant for several disorders. Toxicity studies on Withania somnifera are not available. Acute and sub-acute oral toxicities of Withania somnifera root extract in Wistar rats were evaluated in the present study. In the acute toxicity study, WSR extract was administered to five rats at 2000 mg/kg, once orally and were observed for 14 days. No toxic signs/mortality were observed. In the sub-acute study, WSR extract was administered once daily for 28 days to rats at 500, 1000 and 2000 mg/kg, orally. No toxic signs/mortality were observed. There were no significant changes (P < 0.05) in the body weights, organ weights and haemato-biochemical parameters in any of the dose levels. No treatment related gross/histopathological lesions were observed. The present investigation demonstrated that the no observed adverse effect level was 2000 mg/kg body weight per day of hydroalcoholic extract of W. somnifera in rats and hence may be considered as non-toxic.

Toxicopathological studies on the effects of aflatoxin B(1), ochratoxin A and their interaction in New Zealand White rabbits.

New Zealand White rabbits, divided into 4 groups were fed with feed containing aflatoxin B(1) (AFB(1)) @ 0.5 ppm (group I), ochratoxin A (OA) @ 1 ppm (group II), AFB(1) and OA @ 0.5 ppm and 1 ppm, respectively (group III) and standard feed (group IV) for 60 days. Mortality and decrease in body weight were highest in the interaction group. Superoxide dismutase, catalase and malondialdehyde levels were increased in all the toxin fed groups with maximum elevation in group III. Significant decrease in the antibody titre to sRBC was observed in groups I and II. Significant reduction of HI and CMI responses was observed in group III. Grossly, liver was the most affected organ in AFB(1) treated animals. Microscopically, vacuolar degeneration of hepatocytes, bile duct epithelial hyperplasia and hypertrophy and peribiliary fibrosis were consistently observed. Ultrastructurally, hepatocytes revealed varying degrees of degeneration, swollen endoplasmic reticulum and pleomorphism of mitochondria. OA produced significant nephrotoxicity with the pale, soft and enlarged kidneys showing discoloured foci over the surface. Microscopically, kidneys revealed degeneration of the proximal convoluted tubules and the testes were atrophic. Ultrastructurally, disruption of the mitochondrial membrane and swelling of the endoplasmic reticulum were observed. In group III, gross and histopathological changes were observed both in liver and kidneys and were of greater severity as compared to those of groups I and II. Ultrastructurally, hepatocytes revealed nuclear distortion, marginated heterochromatin, chromatolysis, electron opaque mitochondria with vacuolations and disarray of cristae and loss of cytoplasmic organelles. The results suggested an additive interaction of AFB(1) and OA in rabbits.

Prevention of age-associated neurodegeneration and promotion of healthy brain ageing in female Wistar rats by long term use of bacosides.

Bacopa monnieri (L.), popularly known as Brahmi, is a revered Ayurvedic medicinal plant used as nerve tonic since time immemorial. The present study aims to investigate the neuroprotective effect of bacosides, the active saponins of Bacopa monnieri (L.) against age associated neurodegeneration and its impact over the prevention of Senile Dementia of Alzheimer's Type (SDAT). The optimum dose of bacosides with no adverse effect was selected by screening its dose dependant activity on ageing biomarker lipofuscin and SDAT biomarker neurotransmitter acetylcholine in the aged female Wistar rat brain. The selected therapeutic dose of bacosides (200 mg/kg) was orally administered for 3 months in middle aged and aged rats and further investigated for its protective action against age associated alterations in neurotransmission system, behavioral paradigms, hippocampal neuronal loss and oxidative stress markers. The results of the present study suggest that bacosides may act as a potential therapeutic intervention in forestalling the deleterious effects of ageing and preventing the age associated pathologies like SDAT.