Predictors of metabolic syndrome in Asian north Indians with newly detected type 2 diabetes.

BACKGROUND & OBJECTIVE: The identification of metabolic syndrome (MS) among patients with type 2 diabetes (T2DM) is of great importance, since those with MS carry a cluster of cardiovascular risk factors. This study evaluates suitable criteria with high efficiency in diagnosing MS and to identify the strongest predictors of MS in newly detected type 2 diabetes individuals. METHODS: Newly detected type 2 diabetes (<6 months) patients were assessed. The MS was assessed by WHO, National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III), modified NCEP-ATP-III and International Diabetes Federation (IDF) criteria. Receiver operating characteristics (ROC) curves of serum triglycerides, HDL, and waist circumference were created for the prediction of MS and the area under the corresponding curves (AUC) were used to evaluate the predictive efficiency of each MS parameter. Different cut points in the selected variables and the corresponding sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were estimated. RESULTS: Among the 563 newly detected T2DM individuals, the presence of MS ranged from 57 to 68 per cent according to the different criteria. The higher percentage of MS was observed in modified NCEPATP III criteria. In comparison to men, presence of MS was higher in women in all the four criteria [198 (67%) vs. 165 (62%); 209 (70%) vs. 111 (42%); 231 (78%) vs. 151 (57%); 222 (75%) vs. 129 (49%)] by modified WHO, NCEP-ATP III, modified NCEP-ATP III, and IDF, respectively. The predictive ability to diagnose MS was highest with modified NCEP-ATP III and lowest with IDF criteria. The optimal cut-off of waist circumference in men and women were 90 and 88 cm respectively. Serum triglyceride in men effectively indicated the presence of MS in newly detected T2DM individuals, whereas, in women the HDL-C was the stronger predictor of MS. INTERPRETATION & CONCLUSION: The study results show that modified NCEP-ATP III criteria predict highest occurrence of MS in newly detected T2DM patients. Elevated serum triglyceride for men and decreased serum HDL-C in women were the strongest single predictors, effectively indicating presence of MS in newly detected T2DM.

Modulation of mitomycin C-induced genotoxicity by acetyl- and thio- analogues of salicylic acid.

BACKGROUND: Recent reports regarding acetylsalicylic acid (ASA) and its metabolites suggest suppressive effects against mitomycin C (MMC)-induced genotoxicity in a mice chromosomal aberration assay. Keeping this in mind, the potential anti-genotoxic effect of the thio-analogue of salicylic acid namely thio-salicylic acid (TSA) was speculated upon. The present study investigated and compared the anti-genotoxic potential of ASA and TSA. MATERIALS AND METHODS: The study was performed in male swiss mice (20+/-2 g) using single-cell gel electrophoresis and a peripheral blood micronucleus assay. ASA and TSA (5, 10 or 20 mg/kg) were administered 15 minutes after MMC (1 mg/kg) once daily for 3 or 7 days. RESULTS: Both ASA and TSA significantly decreased the DNA damage induced by MMC as indicated by a decrease in the comet parameters in bone marrow cells and decreased frequencies of micronucleated reticulocytes in peripheral blood. CONCLUSION: The results clearly demonstrate the anti-genotoxic potential of ASA and TSA.

Inhibition of sodium current by carbamazepine in dorsal root ganglion neurons in vitro.

Carbamazepine (CBZ), one of the most commonly prescribed antiepileptic drug, is proposed to inhibit Na+ channel. In this study, we have investigated the effects of CBZ on Na+ current, evoked in cultured dorsal root ganglion (DRG) neurons from neonatal rats using whole cell patch clamp technique. In small DRG neurons (20-25 microm), Na+ current was obtained by blocking K+ and Ca2+ currents with appropriate ion replacement and channel blockers. Separation of the Na+ current components was achieved on the basis of response to the conditioning voltage. The CBZ depressed Na+ current in a dose-dependent manner. The maximal Na+ current was depressed at 300 microM of CBZ, where 94 +/- 5.1% of depression was observed. The depression of normalized current amplitude was found to be 72 +/- 13.2%, 84 +/- 10%, 85 +/- 7.1% and 95 +/- 5.2% at 10, 30, 100 and 300 microM of CBZ concentrations, respectively, at -20 mV test pulse, when compared with control. The depression of current amplitude was observed as 48 +/- 12.3%, 42 +/- 15.2%, 71 +/- 17.7% and 90 +/- 5.8% at 10, 30, 100 and 300 microM of CBZ concentration, respectively, at 0 mV voltage pulse. The depression of Na+ currents was found to be dose-dependant at -20 and -10 mV but not at 0 mV, It is concluded that the depression of Na+ currents by CBZ may be responsible for inhibiting the neurotransmitter release.

Rosiglitazone attenuates the cognitive deficits induced by high fat diet feeding in rats.

The present study was designed to test the hypothesis that insulin resistance plays a role in high fat diet feeding induced cognitive deficits. Rats consuming the high fat diet exhibited characteristic features of insulin resistance viz. mild hyperglycemia, hypertriglyceridemia, hypercholesterolemia, and hyperinsulinemia. Further, these rats showed a severe deficit in learning and memory. In contrast, rosiglitazone at the dose of 5 mg/kg, p.o. for 7 days prior to biochemical and behavioral testing significantly lowered the plasma glucose, triglycerides, cholesterol, and insulin levels. These animals also performed better on Morris water maze task, suggesting improved spatial memory. Our data demonstrate that the insulin sensitizers can overcome the cognitive deficits arising from high fat diet feeding, which may be in part mediated through the development of peripheral insulin resistance.

New PPARgamma ligands based on barbituric acid: virtual screening, synthesis and receptor binding studies.

A new series of PPARgamma ligands based on barbituric acid (BA) has been designed employing virtual screening and molecular docking approach. To validate the computational approach, designed molecules were synthesized and evaluated in in vitro radioligand binding studies. Out of the total 14 molecules, 6 were found to bind to the murine PPARgamma with IC(50) ranging from 0.1 to 2.5 microM as compared to reference standard, pioglitazone (IC(50)=0.7 microM).

New PPARgamma ligands based on 2-hydroxy-1,4-naphthoquinone: computer-aided design, synthesis, and receptor-binding studies.

FlexX-based molecular docking study was employed to identify 2-hydroxy-1,4-naphthoquinone as a new 'acidic head group' for the design of a novel series of PPARgamma ligands. To provide the proof of concept, designed molecules were synthesized and evaluated in a standard radioligand-binding assay. Out of eight molecules, four were found to bind to the murine PPARgamma with IC(50) ranging from 0.2 to 56.2 microM as compared to standard pioglitazone, with IC(50) of 0.7 microM.

Chronic administration of pioglitazone attenuates intracerebroventricular streptozotocin induced-memory impairment in rats.

Memory impairment induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) in rats is associated with impaired brain glucose and energy metabolism, oxidative stress and impaired cholinergic neurotransmission. Treatment with antioxidants and cholinergic agonists has been reported to produce beneficial effect in this model. However, no reports are available on drugs that improve glucose utilization and metabolism. In the present study, we evaluated the effects of pioglitazone on cognitive performance, oxidative stress and glucose utilization in ICV STZ injected rats (3 mg/kg, on day 1 and 3). Pioglitazone (10 and 30 mg/kg) was administered per oral (p.o.) for 14 days, starting 5 days prior to STZ injection. Cognitive performance was assessed using step-through passive avoidance and Morris water maze task. Malondialdehyde (MDA) and glutathione levels in brain were estimated as parameters of oxidative stress. Glucose utilization by brain was assessed as the amount of glucose consumed from the media by the brain. ICV STZ injected rats showed a severe deficit in learning and memory associated with increased MDA levels (+67.5%), decreased glutathione levels (-29.2%) and impaired cerebral glucose utilization (-44.4%). In contrast pioglitazone treatment improved cognitive performance, lowered oxidative stress and improved cerebral glucose utilization in ICV STZ rats. The present study demonstrates the beneficial effects of pioglitazone in the ICV STZ induced cognitive deficits, which can be exploited for the dementia associated with diabetes and age-related neurodegenerative disorder, where oxidative stress and impaired glucose and energy metabolism are involved.

Effect of donepezil and lercanidipine on memory impairment induced by intracerebroventricular streptozotocin in rats.

Intracerebroventricular (ICV) injection of streptozotocin (STZ) causes cognitive impairment in rats. ICV STZ is known to impair cholinergic neurotransmission by decreasing choline acetyltransferase (ChAT) levels, glucose and energy metabolism in brain and synthesis of acetyl CoA. However, no reports are available regarding the cholinesterase inhibitors in this model. In aging brain, reduced energy metabolism increases glutamate release, which is blocked by L-type calcium channel blockers. These calcium channel blockers have shown beneficial effects on learning and memory in various models of cognitive impairment. The present study was designed to investigate the influence of chronic administration of donepezil (cholinesterase inhibitor, 1 and 3 mg/kg) and lercanidipine (L-type calcium channel blocker, 0.3 and 1 mg/kg) on cognitive impairment in male Sprague-Dawley rats injected twice with ICV STZ (3 mg/kg) bilaterally on days 1 and 3. ICV STZ injected rats developed a severe deficit in learning and memory indicated by deficits in passive avoidance paradigm and elevated plus maze as compared to control rats. Cholinesterase activity in brain was significantly increased in ICV STZ injected rats. Donepezil dose-dependently inhibited cholinesterase activity and improved performance in memory tests at both the doses. Lercanidipine (0.3 mg/kg) showed significant improvement in memory. When administered together, the effect of combination of these two drugs on memory and cholinesterase activity was higher than that obtained with either of the drugs when used alone.

Discovery of a bulky 2-tert-butyl group containing primaquine analogue that exhibits potent blood-schizontocidal antimalarial activities and complete elimination of methemoglobin toxicity.

To eliminate an unwarranted metabolic pathway of the quinoline ring, a set of two compounds, where C-2 position of the antimalarial drug primaquine is blocked by metabolically stable bulky alkyl group are synthesized. Compound 2 [R = C(CH(3))(3)] of the series has produced excellent antimalarial efficacy against P. berghei and highly virulent multidrug-resistant P. yoelii nigeriensis strain in vivo. Compound 2 was also evaluated for methemoglobin (MetHb) toxicity. This study describes the discovery of a highly potent blood-schizontocidal antimalarial analogue 2, completely devoid of MetHb toxicity.

Role of L-type Ca(2+) channels in pertussis toxin induced antagonism of U50,488H analgesia and hypothermia.

Previous studies have shown that the kappa-opioid effects are sensitive to pertussis toxin (PTX) and affected by Ca(2+) fluxes. However, the possible involvement of Ca(2+) channels in PTX-induced inhibition of kappa-opioid effects has not been reported. The effect of intracerebroventricular (i.c.v.) treatment of pertussis toxin (1 microg/rat, PTX) or saline on the kappa-opioid agonist, U-50,488H (U5H) induced tail-flick analgesia and hypothermia in rats was determined. The effect of nimodipine (NIM), a dihydropyridine (DHP)-sensitive Ca(2+) channel blocker (CCB), on PTX-induced modulation of U5H effects was examined. The DHP ligand, [3H]PN200-110 binding was also determined in both PTX and saline treated rats to study the possible involvement of L-type Ca(2+) channels in PTX modulation of kappa-opioid agonist effects. The analgesia and change in colonic temperature were determined using tail-flick analgesiometer and telethermometer, respectively. U5H (40 mg/kg, i.p.) produced significant analgesic and hypothermic responses. PTX treatment significantly (P<0.01) antagonized the analgesic and hypothermic effects of U5H. Acute pretreatment of NIM (1 mg/kg, i.p.) 15 min prior significantly (P<0.01) reversed the PTX-induced antagonism of U5H effects. In the binding study, PTX treatment (72 h before) resulted in a significant (P<0.005) upregulation (+45% vs. saline control) of DHP binding (B(max)) with no change in affinity (K(d)). The results showed significant upregulation of DHP binding in accordance with PTX-induced antagonism of U5H effects and this blockade was reversed by NIM. Thus, present results suggest that U5H-induced analgesia and hypothermia may be mediated through PTX-sensitive transducer G-proteins (G(i/o)) coupled to L-type Ca(2+) channels.

Regulation of dihydropyridine-sensitive Ca(2+) channels during naloxone-induced opioid supersensitivity in rats.

The Ca(2+) channel blocker, nimodipine, increases the chronic naltrexone-induced supersensitivity to morphine analgesia in mice without affecting the density of up-regulated mu-opioid receptors. In the present study, the change in dihydropyridine-sensitive Ca(2+) channels associated with chronic naloxone-induced supersensitivity to morphine analgesia was studied in rat whole-brain membranes using a radiolabeled Ca(2+) channel blocker, [3H]PN200-110 [isopropyl 4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-2,6-dimethyl-5-methoxycarbonylpyridine-3-carboxylate] (0.02-1.0 nmol/l). Rats were chronically treated with naloxone (1 mg/kg, i.p.), nimodipine (1 mg/kg, i.p.) or their respective vehicles twice daily for 10 days. On the 11th day, 16 h after the last injection of either nimodipine or naloxone, morphine (2 mg/kg, i.p.)-induced tail-flick analgesia was determined or rats were killed for the binding study. Chronic naloxone significantly potentiated (+84%) the morphine-induced analgesia. Chronic nimodipine also potentiated (+76%) morphine analgesia. In rats treated with nimodipine and naloxone, there was an additive increase (206%) in morphine analgesia. In binding studies, chronic naloxone resulted in a significant decrease (-39%) in the density (B(max)) of [3H]PN200-110 binding with no change in K(d) value when compared to the effect of chronic vehicle. Chronic nimodipine resulted in a slight but significant (+14.5%) increase in the B(max) of [3H]PN200-110. However, when nimodipine was co-administered with naloxone, it not only reversed the down-regulation but actually up-regulated (+25%) [3H]PN200-110 binding with no change in K(d) value. Our results show significant down-regulation of [3H]PN200-110 binding in association with naloxone-induced analgesic supersensitivity to morphine. The supersensitivity was also observed following chronic blockade of up-regulated Ca(2+) channels by nimodipine. These results indicate an important role of L-type Ca(2+) channel regulation in naloxone-induced analgesic supersensitivity to morphine.

Enhancement of alpha-adrenoceptor-mediated responses in prostate of testosterone-treated rat.

The present study was undertaken to investigate the effect of testosterone on the alpha-adrenoceptor-mediated contractile responses in ventral lobe of rat prostate. Contractile responses to various alpha-adrenoceptor agonists (phenylephrine, A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulphonamide), clonidine, guanfacine, ST587 ((2,3-dihydro-benzo[1,4]dioxin-2-ylmethyl)-[2-(2,6-dimethoxy-phenoxy)-ethyl]-amine) and xylazine) were tested in prostate strips obtained from control and testosterone (3 mg/kg, s.c. 5 days a week for 15 days-10 doses total)-treated rats. Dose-response curves for alpha-adrenoceptor agonists in testosterone-treated animals showed a leftward shift, indicating increased sensitivity of tissue to alpha-adrenoceptor agonists. To find the mechanism of increased sensitivity, K(A) value and receptor reserve of phenylephrine were estimated. Neither the K(A) value nor the receptor reserve of phenylephrine was altered in testosterone-treated rats. The concentration-occupancy curve for A61603 was shifted leftward and the K(A) value for A61603 decreased about four-fold. The K(B) value of 2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4-benzodioxane (WB4101) was not altered, however, the K(B) value for prazosin was decreased approximately 5.5-fold. These findings indicate that the testosterone-mediated increase in sensitivity of prostate to alpha-adrenoceptor agonists is due to alterations in the alpha(1)-adrenoceptor pool.

Role of L-type Ca2+ channels in attenuated morphine antinociception in streptozotocin-diabetic rats.

The role of L-type Ca2+ channels in morphine antinociception was studied in streptozotocin-induced diabetic and control rats, using [3H]PN200-110 [isopropyl 4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-2,6-dimethyl-5-methoxycabonylpyridine-3-caboxylate] binding (0.005-1.0 nmol/l) and rat whole brain membranes, to determine if the attenuation of morphine antinociception was related to alterations in dihydropyridine-sensitive Ca2+ channel binding characteristics. The tail-flick antinociceptive effect of morphine (4 mg/kg, i.p.) was significantly reduced in diabetic rats in comparison to that in controls. Nimodipine (0.1-3 mg/kg, i.p.) did not produce antinociception but significantly potentiated the morphine response in control rats. Nimodipine (0.3-3 mg/kg, i.p.) reversed the attenuation of morphine antinociception in a dose-dependent manner in diabetic rats. Moreover, insulin (2 U/kg, s.c.) [correction of mu/kg] reversed the attenuated morphine antinociception in streptozotocin-diabetic rats. A significant increase in the Bmax (+41%) of [3H]PN200-110 binding was observed in diabetic rat brain membranes compared to that in control rats. However, there was no change in affinity (Kd) value of [3H]PN200-110. The reduced morphine response in diabetic rats, in accordance with up-regulation of dihydropyridine sites, may be due to an increased Ca2+ influx through L-type channels. These results suggest a functional role of L-type Ca2+ channels in morphine antinociception and the diabetic state may lead to alterations in their density.

Ginseng total saponin potentiates acute U-50,488H-induced analgesia and inhibits tolerance to U-50,488H-induced analgesia in mice.

In the present study, an attempt has been made to investigate whether the potentiating effect of U-50,488H (U50)-induced analgesia by ginseng total saponin (GTS) is playing a role in inhibiting the tolerance to U50-induced analgesia as measured using the tail-flick test in mice. GTS (100 and 200 mg/kg i.p.), on acute administration, potentiated the U50 (40 mg/kg i.p.)-induced analgesia in U50-naive mice. Twice daily administration of U50 (40 mg/kg i.p.) for 6 days resulted in tolerance to U50-induced analgesia in mice. Chronic administration (Days 4-6) of GTS (50, 100, and 200 mg/kg i.p.) to U50-tolerant mice dose-dependently inhibited the tolerance to U50-induced analgesia. On the other hand, chronic administration of GTS (50, 100, and 200 mg/kg i.p.) dose-dependently potentiated the U50-induced analgesia in U50-naive mice. The dose-response curve to U50-induced analgesia in U50-tolerant mice was shifted rightward (2.6-fold) as compared to U50-naive mice, indicating the development of tolerance to U50-induced analgesia. GTS (100 mg/kg i.p. o.d.), on chronic administration, prevented the rightward shift of dose-response curve to U50-induced analgesia in U50-tolerant mice, whereas in U50-naive mice it resulted in leftward shift (0.6-fold). It can be concluded that acute and chronic administration of GTS potentiates the U50-induced analgesia in U50-naive mice. The potentiating effect of GTS on U50-induced analgesia may be partially responsible in the inhibition of tolerance to U50-induced analgesia in mice.

Melatonin inhibits the development of tolerance to U-50,488H analgesia via benzodiazepine-GABAAergic mechanisms.

Melatonin, a primary secretory product of pineal gland, is known to produce many of its pharmacological actions via benzodiazepine-gamma-aminobutyric acidA (GABAA)ergic mechanisms. Recently, we showed that benzodiazepine-GABAAergic mechanisms play an important role in U-50,488H (U50) analgesia and its tolerance. Hence, in the present study, the effect of melatonin on U50 analgesia and its tolerance was investigated. Furthermore, the possible role of benzodiazepine-GABAAergic mechanisms in the actions of melatonin on U50 analgesia was investigated. All experiments were performed using the radiant tail-flick test for mice. Melatonin [0.2, 1 and 5 mg/kg, intraperitoneal (i.p.)] neither produced analgesia nor affected the acute U50 (40 mg/kg, i.p.) analgesia. Tolerance to U50 analgesia was induced by administering U50 (40 mg/kg, i.p.) twice daily over 6 days. Treatment with melatonin (1 and 5 mg/kg, i.p) 15 min prior to each dose of U50 inhibited the development of tolerance, whereas a low dose of melatonin (0.2 mg/kg, i.p.) did not. The inhibition of U50 tolerance by melatonin was reversed by the chronic treatment with flumazenil (0.1 mg/kg), a benzodiazepine receptor antagonist and picrotoxin (1 mg/kg), a GABAA-gated chloride channel blocker. Flumazenil and picrotoxin neither affected tail-flick latencies nor altered acute U50 analgesia and its tolerance. Interestingly, chronic 6-day melatonin treatment in a vehicle (U50-naive) group did not alter U50 analgesia measured on day 7. Together, these findings suggest that melatonin interferes with the neural mechanisms involved in the development of tolerance to U50 analgesia. The inhibition of U50 tolerance by melatonin was reversed by flumazenil and picrotoxin treatment, suggesting that benzodiazepine-GABAAergic mechanisms play an important role in the development of tolerance to U50 analgesia and that melatonin inhibits the development of U50 tolerance via benzodiazepine-GABAAergic mechanisms.

Role of Ca2+ channels on the hypothermic response produced by activation of kappa-opioid receptors.

The effect of nimodipine (NIM) and lercanidipine (LER) 1,4-dihydropyridine (DHP) calcium channel blockers (CCBs) on the hypothermic response of selective kappa-opioid receptor agonists U50,488H (U50), PD117,302 (PD) and U69,593 (U69) was determined in rats by recording colonic temperature using digital telethermometer. Intraperitoneal (i.p.) injections of U50 (7.5, 15, 22.5 and 40 mg/kg), PD (7.5, 15 and 22.5 mg/kg) and U69 (5 and 20 mg/kg) produced a dose-dependent hypothermic response. However, higher doses of U50 (60 and 80 mg/kg) produced hypothermia, which is less when compared to that produced by 22.5-mg/kg dose of U50. NIM (1 mg/kg i.p.; 15 min prior) and LER (0.3 mg/kg i.p.; 15 min prior) did not produce any change in basal colonic temperature. Treatment of NIM and LER potentiated the U50 (7.5, 15, 22.5 and 40 mg/kg)-induced hypothermic effect. NIM did not potentiate hypothermia produced by U50 (60 mg/kg). On the other hand, PD (7.5, 15 and 22.5 mg/kg)- and U69 (5 and 20 mg/kg)-induced hypothermia was unaffected by the pretreatment of either NIM or LER. This differential modulation of kappa-opioid agonist-induced hypothermia by CCBs suggest that there may be two mechanisms, Ca(2+)-sensitive and Ca(2+)-insensitive, involved in kappa-opioid agonist-induced hypothermic response.

Increased contractile responses to 5-Hydroxytryptamine and Angiotensin II in high fat diet fed rat thoracic aorta.

BACKGROUND: Feeding normal rats with high dietary levels of saturated fat leads to pathological conditions, which are quite similar to syndrome X in humans. These conditions such as hypertriglyceridemia, hypercholesterolemia, obesity, and hyperglycemia might induce hypertension through various mechanisms. Metabolic syndrome and the resulting NIDDM represent a major clinical challenge because implementation of treatment strategies is difficult. Vascular abnormalities probably contribute to the etiology of many diabetic complications including nephropathy, neuropathy, retinopathy, and cardiomyopathy. It has been shown that in Streptozotocin induced diabetic animals there is an increase in maximal responses to 5-Hydroxytryptamine and Angiotensin II. The purpose of this study was to evaluate High fat diet fed rats for the development of hypertriglyceridemia, hypercholesterolemia, hyperinsulinemia and hyperglycemia and to assess their vascular responses to 5-Hydroxytryptamine and Angiotensin II. METHODS: Male Sprague Dawley rats were used for this study and were divided into two equal groups. One of the groups was fed with normal pellet diet and they served as the control group, whereas the other group was on a high fat diet for 4 weeks. Body weight, plasma triglycerides, plasma cholesterol, and plasma glucose were measured every week. Intraperitoneal glucose tolerance test was performed after 4 weeks of feeding. At the end of fourth week of high fat diet feeding, thoracic aortae were removed, and cut into helical strips for vascular reactivity studies. Dose-response curves of 5-Hydroxytryptamine and Angiotensin II were obtained. RESULTS: There was no significant difference in pD2, with 5-Hydroxytryptamine and Angiotensin II in both groups but Emax was increased. CONCLUSIONS: These results suggest that hypertension in high fat diet rats is associated with increased in vitro vascular reactivity to 5-HT and Ang II.

Accumulated polymer degradation products as effector molecules in cytotoxicity of polymeric nanoparticles.

Polymeric nanoparticles (PNPs) are a promising platform for drug, gene, and vaccine delivery. Although generally regarded as safe, the toxicity of PNPs is not well documented. The present study investigated in vitro toxicity of poly-ε-caprolactone, poly(DL-lactic acid), poly(lactide-cocaprolactone), and poly(lactide-co-glycide) NPs and possible mechanism of toxicity. The concentration-dependent effect of PNPs on cell viability was determined in a macrophage (RAW 264.7), hepatocyte (Hep G2), lung epithelial (A549), kidney epithelial (A498), and neuronal (Neuro 2A) cell lines. PNPs show toxicity at high concentrations in all cell lines. PNPs were efficiently internalized by RAW 264.7 cells and stimulated reactive oxygen species and tumor necrosis factor-alpha production. However, reactive nitrogen species and interleukin-6 production as well as lysosomal and mitochondrial stability remained unaffected. The intracellular degradation of PNPs was determined by monitoring changes in osmolality of culture medium and a novel fluorescence recovery after quenching assay. Cell death showed a good correlation with osmolality of culture medium suggesting the role of increased osmolality in cell death.

Cellular uptake, intracellular trafficking and cytotoxicity of silver nanoparticles.

Silver nanoparticles (Ag NPs) are used in consumer products and wound dressings due to their antimicrobial properties. However, in addition to toxic effects on microbes, Ag NPs can also induce stress responses as well as cytotoxicity in mammalian cells. We observed that Ag NPs are efficiently internalized via scavenger receptor-mediated phagocytosis in murine macrophages. Confocal and electron microscopy analysis revealed that internalized Ag NPs localize in the cytoplasm. Ag NPs cause mitochondrial damage, induce apoptosis and cell death. These effects were abrogated in presence of Ag ion-reactive, thiol-containing compounds suggesting the central of Ag ions in Ag NP toxicity. Quantitative image analysis revealed that intracellular dissolution of Ag NPs occurs about 50 times faster than in water. In conclusion, we demonstrate for the first time that Ag NPs are internalized by scavenger receptors, trafficked to cytoplasm and induce toxicity by releasing Ag ions.

Insulin resistance induces a segmental difference in thoracic and abdominal aorta: differential expression of AT1 and AT2 receptors.

OBJECTIVES: The study was pursued to understand and compare the vascular reactivity to angiotensin II (Ang II) and its receptor expression in thoracic and abdominal aorta under insulin resistance. METHODS: Vascular reactivity to Ang II was recorded isometrically, AT1/AT2 receptor gene and protein expression was checked by RT-PCR and western blotting, respectively, and abundance of phospho (serine-10 Ph) H3 on promoter regions of Agtr1/Agtr2 genes was done by chromatin immunoprecipitation assay in aortic rings isolated from high fat diet (HFD)-fed rats. RESULTS: Our functional studies showed an increased (Emax in mg/mm: Con: 319 ±â€Š29 and HFD: 1095 ±â€Š72, P < 0.001) and unaltered (Emax in mg/mm: Con: 299 ±â€Š29 and HFD: 350 ±â€Š20, mean ±â€ŠSEM, n = 6) Ang II-induced contractile responses in thoracic and abdominal aorta of HFD rats, respectively, as compared to control rats. Interestingly, AT2R-mediated relaxation was increased in abdominal aorta (% relaxation: Con: 25 ±â€Š5.3 and HFD: 76.4 ±â€Š8.9, P < 0.001) of HFD rats but not in thoracic aorta (% relaxation: Con: 25 ±â€Š5.2 and HFD: 32 ±â€Š5.2, mean ±â€ŠSEM, n = 6). At the molecular level, increased mRNA (∼14-folds) and protein expression (∼2.5-folds) of AT2R in abdominal aorta of HFD rats was found as compared to control rats. However, AT1R mRNA and protein expression did not show any change. Chromatin immunoprecipitation with phospho H3 showed increased abundance of ser-10 phosphorylation on Agtr1 and Agtr2 gene promoter regions in thoracic and abdominal segments, respectively. But it got decreased on Agtr2 and Agtr1 genes promoter regions in thoracic and abdominal segments, respectively. CONCLUSION: We provide first evidence that insulin resistance induces segmental difference in thoracic and abdominal aorta and this may provide reason of heterogeneity for incidence of aneurysms.