Influence of beta-radiation sterilisation in properties of new chitosan/soybean protein isolate membranes for guided bone regeneration

Novel chitosan (cts) and soybean protein isolate (SI) blended membranes were prepared. These membranes were produced by solvent casting. Besides combining the advantages of both materials, cts/SI membranes exhibit a biphasic structure that will eventually originate in situ porous formation, through a two-step degradation mechanism. In this particular work the effect of beta-radiation over the properties of these membranes was evaluated. beta-radiation sterilisation was performed at three different doses (25, 50 and 100 kGy) and eventual surface chemical changes were evaluated by Fourier transformed infrared--with attenuated total reflection and contact angle measurements. Moreover, eventual bulk properties changes due to beta-radiation were assessed by means of mechanical tensile tests and water uptake measurements. In general, no substantial changes were detected on the studied properties, with the exception of the surface energy that was found to be slightly increased for higher applied doses.

Anti-inflammatory effect of kaurenoic acid, a diterpene from Copaifera langsdorffii on acetic acid-induced colitis in rats

Kaurenoic acid, a diterpene from Copaifera langsdorffii (Leguminaceae), was evaluated on rat colitis induced by acetic acid. Rats were pretreated orally (15 and 2 h before) or rectally 2 h before induction of colitis with kaurenoic acid (50 and 100 mg/kg) or vehicle (1 ml, 3% DMSO). Colitis was induced by intracolonic instillation of a 2 ml of 4% (v/v) acetic acid solution and, 24 h later, the colonic mucosal damage was analysed macroscopically for the severity of mucosal damage, the myeloperoxidase (MPO) activity and the malondialdehyde (MDA) levels in the colon segments. A marked reduction in gross damage score (52% and 42%) and wet weight of damaged colon tissue (39% and 32%) were observed in rats that received 100 mg/kg kaurenoic acid, respectively, by rectal and oral routes. This effect was confirmed biochemically by a two- to three-fold reduction of colitis associated increase in MPO activity, the marker of neutrophilic infiltration and by a marked decrease in MDA level, an indicator of lipoperoxidation in colon tissue. Furthermore, light microscopy revealed the marked diminution of inflammatory cell infiltration and submucosal edema formation in the colon segments of rats treated with the test compound. These findings indicate the anti-inflammatory potential of kaurenoic acid in acetic acid-induced colitis.

Effects of nitric oxide synthase inhibitors and melatonin on the hyperglycemic response to streptozotocin in rats

Recent studies evidence that peroxynitrite is spontaneously formed when nitric oxide (NO) and superoxide coexist and suggest that it is likely to be involved in the destruction of the pancreatic beta cells. We examined whether drugs that inhibit nitric oxide synthase (NOS) or scavenge peroxynitrite could abrogate STZ-induced hyperglycemia in rats. Blood glucose levels were measured before (0 h) and 24, 48, and 72 h following intraperitoneal administration of 60 mg/kg streptozotocin (STZ). The levels of blood sugar in STZ-treated control animals were significantly elevated at all time points of observation with a peak increase at 48 h. The hyperglycemic response of STZ was found to be significantly reduced in animals pretreated with aminoguanidine (50 mg/kg i.p.), an inducible isoform-selective NOS (iNOS) inhibitor with antioxidant property, and by melatonin (6 mg/kg i.p.), an antioxidant that also prevents peroxynitrite formation but not by Nw-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg i.p.), and 7-nitroindazole (7-NI, 50 mg/kg i.p.), the constitutive inhibitors of endothelial and neuronal NOS, respectively. These findings indicate the possible participation of iNOS-derived NO as well as oxygen free radicals in STZ-induced pancreatic beta cell destruction and compounds that act as scavengers of peroxynitrite may offer protection against such a damage.

Blood glucose- and triglyceride-lowering effect of trans-dehydrocrotonin, a diterpene from Croton cajucara Benth., in rats

AIM

The objective of this study was to assess in rats the antidiabetic effects (i.e. reduction of hyperglycaemia and hypertriglyceridaemia) of trans-dehydrocrotonin (t-DCTN), a bioactive diterpene isolated from the popular medicinal plant Croton cajucara.

METHODS

Hyperglycaemia was induced by intraperitoneal injection of streptozotocin (STZ) and hypertriglyceridaemia by oral administration of ethanol in rats. The blood glucose levels were measured by the glucose oxidase method using commercially available enzyme kits.

RESULTS

Treating rats with t-DCTN (50 mg/kg) significantly reduced STZ-induced increases in blood glucose levels as well as ethanol-induced increases in blood triglycerides.

CONCLUSION

The results suggest that t-DCTN has an antidiabetic potential that warrants further research on its mechanism and clinical significance.

Effect of trans-dehydrocrotonin, a 19-nor-clerodane diterpene from Croton cajucara on experimental hypertriglyceridaemia and hypercholesterolaemia induced by Triton WR 1339 (tyloxapol) in mice

The effect of trans-dehydrocrotonin (t-DCTN) from Croton cajucara Benth. was investigated in mice on Triton WR 1339 (tyloxapol)-induced hypercholesterolaemia and hypertriglyceridaemia. Mice treated with single application of tyloxapol (400 mg/kg, i.p.) demonstrated significantly increased blood levels of total cholesterol and triglycerides at 24 h and 48 h after its injection, compared to normal controls. These increases were found to be markedly suppressed in animals treated orally with 25 and 50 mg/kg t-DCTN or 100 mg/kg gemfibrozil, an established antihypercholesterolaemic drug. These results suggest that t-DCTN may be a suitable candidate for combating pathologies associated with hyperlipaemia.

[Serological and epidemiological features of canine American tegumentary Leishmaniasis from Maricá, Rio de Janeiro, Brazil]

A sample of 261 dogs from 134 households located in a periurban area of Maricá, Rio de Janeiro, Brazil, was studied to evaluate serologic reactions and active infection of american tegumentary leishmaniasis (ATL). Eight dogs presented lesions suggestive of ATL, but this was isolated in only three. Using ELISA, 24.5% (64/261) of the dogs studied were positive (sensitivity = 66% and specificity = 76%), associated with isolation in 2 animals and 0.4% (1/261) by indirect immunofluorescence assay (IIF) with no association with isolation. In order to reduce the unspecific reactions to ELISA, a second criterion was used to obtain the cutoff (sensitivity = 33% and specificity = 93%), resulting in a reactivity of 6.9 % (18/261) associated to isolation in a single animal. As observed in this study, serologic results by IIF were not associated with active infection and ELISA showed high unspecific reactions, indicating that the serologic reactions alone are not recommended for ATL diagnosis. ATL scars were been observed in 7 persons in the region and active lesion, under treatment, was observed in one patient. The finding of active lesions, either in dogs or humans, confirmed the existence of active tegumentary leishmaniasis in Maricá, indicating the need for further studies to evaluate the importance of this infection in the municipality.

Studies on the antidiarrhoeal effect of dragon's blood from Croton urucurana

The red sap obtained by slashing the bark of Croton urucurana Baill. (Euphorbiaceae), also known as dragon's blood, was screened for a possible antidiarrhoeal activity on castor oil-induced diarrhoea in rats, cholera toxin-induced intestinal secretion in mice and on small intestinal transit in mice. Dragon's blood at an oral dose of 600 mg/kg caused in marked inhibition of the diarrhoeal response following castor oil administration as well as the intestinal fluid accumulation promoted by cholera toxin. At a similar dose the red sap significantly inhibited the small intestinal transit which was, however, found to be independent of the opioid mechanism. These results suggest a potential usefulness of the red sap from Croton urucurana Baill. in the control of secretory diarrhoea associated pathologies.

Beta-endorphin-induced feeding: pharmacological characterization using selective opioid antagonists and antisense probes in rats

Ventricular administration of the opioid beta END induces feeding in rats. Since its pharmacological characterization has not been fully identified, the present study examined whether equimolar doses of general and selective opioid antagonists as well as AS ODN opioid probes altered spontaneous daytime feeding over a 4-h time course elicited by beta END. beta END-induced feeding was significantly reduced by moderate (20--40-nmol, i.c.v.) doses of general (naltrexone) opioid antagonists, and lower (0.5--40-nmol) doses of selective mu (beta-funaltrexamine)-antagonists. Correspondingly, AS ODN probes directed against either exons 1, 3, or 4, but not exon 2, of the mu-opioid receptor clone reduced beta END-induced feeding; a missense ODN control probe was ineffective. The delta-antagonist Nti (20-40 nmol) reduced beta END-induced feeding to a lesser degree, and AS ODN probes targeting exon 1, but not 2 or 3, of the delta-opioid receptor clone significantly reduced beta END-induced feeding. Although the selective kappa(1)-receptor antagonist NBNI (20-40 nmol) significantly reduced beta END-induced feeding, this response was not altered by AS ODN probes directed against either exons 1, 2, or 3 of either the KOR-1 clone or the kappa(3)-like opioid receptor clone. These converging antagonist and AS ODN data firmly implicate the mu-opioid receptor in the mediation of beta END-induced feeding. The relative lack of convergence between the lesser effectiveness of Nti and NBNI in reducing beta END-induced feeding, and the lack of effectiveness of their corresponding AS ODN probes suggest that delta- and kappa-receptors play a minimal role in the mediation of this response.

1,8-cineole protects against liver failure in an in-vivo murine model of endotoxemic shock

The effects of 1,8-cineole on D-galactosamine/lipopolysaccharide (GalN/LPS)-induced shock model of liver injury was investigated in mice. The co-administration of GalN (700 mg kg(-1), i.p.) and LPS (5 microg kg(-1), i.p.) greatly elevated serum concentrations of tumour necrosis factor-alpha (TNF-alpha), alanine aminotransferase and aspartate aminotransferase, and induced massive hepatic necrosis and lethality in 100% of control mice. Pretreatment with 1,8-cineole (400 mg kg(-1), p.o.) and dexamethasone (1 mg kg(-1), s.c.), 60 min before GalN/LPS, offered complete protection (100%) against the lethal shock and acute elevation in serum TNF-alpha and serum transaminases. Hepatic necrosis induced by GalN/LPS was also greatly reduced by both 1,8-cineole and dexamethasone treatment. The results indicate that 1,8-cineole protects mice against GalN/LPS-induced liver injury through the inhibition of TNF-alpha production, and suggest that 1,8-cineole may be a promising agent to combat septic-shock-associated pathologies.

The lipid-lowering effect of trans-dehydrocrotonin, a clerodane diterpene from Croton cajucara Benth. in mice fed on high-fat diet

The clerodane diterpene trans-dehydrocrotonin extracted and isolated from the stem bark of Croton cajucara Benth. was investigated for its lipid-lowering effect in mice fed on a high-fat diet. Mice fed on a high-fat diet for a two-week period demonstrated significantly increased blood levels of total cholesterol and triglycerides, compared with normal controls. Oral treatment with trans-dehydrocrotonin at a dose of 25 or 50 mg kg(-1) daily markedly suppressed the high-fat-diet associated rise in total cholesterol and triglyceride levels. The hypocholesterolaemic effect of trans-dehydrocrotonin was more prominent at the dose of 50 mg kg(-1) with significant decreases in high-density lipoprotein, very-low-density lipoprotein and low-density lipoprotein cholesterol levels. The lower atherogenic index of the trans-dehydrocrotonin-treated groups suggests the hypolipidaemic potential of this plant-based drug. These results indicate that orally administered trans-dehydrocrotonin is effective in suppressing high-fat-diet-induced hyperlipidaemia in mice and suggest its likely beneficial use as anti-atherogenic agent.

Role of D(1) and D(2) dopamine receptors in the acquisition and expression of flavor-preference conditioning in sham-feeding rats

The present study examined the effects of D(1) and D(2) antagonists on flavor-preference conditioning by the sweet taste of sucrose. All sessions were conducted under sham-feeding conditions to minimize post-ingestive influences. The rats were trained in alternating, one-bottle sessions to sham-feed a 16% sucrose solution containing one novel flavor (CS+) and a less-preferred 0.2% saccharin solution containing a different flavor (CS-). Three groups of food-restricted rats were treated with either vehicle (control group), the D(1) antagonist, SCH23390 (200 nmol/kg), or the D(2) antagonist, raclopride (200 nmol/kg) during one-bottle training. A fourth group (yoked group) was vehicle-treated and its training intakes were matched to that of the D(1) and D(2) drug groups. Preferences were assessed in two-bottle tests with the CS+ and CS- flavors presented in mixed 8% sucrose+0.1% saccharin solutions following systemic doses of 0, 200, or 800 nmol/kg of either the D(1) or D(2) antagonists. All groups significantly preferred the CS+ flavor in vehicle tests, although the preferences were weaker in the D(1), D(2), and yoked groups compared to the control group. All groups selectively reduced their CS+ intakes when treated with either D(1) or D(2) antagonists during two-bottle testing, and the CS+ preference was blocked at the higher doses. These data show that D(1) and D(2) receptor antagonists block the expression of a sucrose-conditioned preference, but produces substantially lesser effects upon the acquisition of this form of flavor conditioning.

Morphine and morphine-6beta-glucuronide-induced feeding are differentially reduced by G-protein alpha-subunit antisense probes in rats

Although morphine and its active metabolite, morphine-6beta-glucuronide (M6G), each induce mu-opioid receptor-sensitive feeding, different antisense oligodeoxynucleotide (AS ODN) probes directed against the MOR-1 clone produce distinct effects. Thus, MOR-1 AS ODN probes directed against exons 1 or 4 reduce morphine-, but not M6G-induced feeding, whereas probes directed against exons 2 or 3 reduce M6G-, but not morphine-induced feeding. AS ODN probes directed against different G-protein alpha-subunits differentially reduced morphine (G(ialpha2)) and M6G (G(ialpha1))-induced analgesia. The present study evaluated the ability of AS ODN probes directed against G-protein alpha-subunits to reduce feeding induced by morphine and M6G in rats. The AS ODN probes (25 microg, i.c.v.) were administered once 24 h prior to morphine (5 microg, i.c.v.) or M6G (250 ng) and spontaneous free feeding was assessed 1, 2 and 4 h thereafter. In agreement with analgesic studies, morphine-induced feeding was significantly reduced by the G(ialpha2) AS ODN probe. Morphine-induced feeding was unaffected by AS ODN probes directed against either G(ialpha1), G(ialpha3), G(oalpha), G(x/zalpha), G(qalpha) or a nonsense control probe, and was significantly enhanced by pretreatment with the G(salpha) probe. In contrast, M6G-induced feeding was significantly reduced by AS ODN probes directed against either G(ialpha1), G(ialpha3) or G(x/zalpha), whereas AS ODN probes targeting G(ialpha2), G(oalpha), G(salpha), G(qalpha) or a nonsense control probe were ineffective. When M6G-induced feeding was assessed at a dose (500 ng) which was sensitive to MOR-1 AS ODN effects, none of the G-protein alpha-subunit AS ODN probes were effective. These data indicate that morphine and M6G-induced feeding are mediated through different G-protein alpha-subunits, and provide further evidence for separate and distinct molecular mechanisms mediating these functional responses through different opioid receptors. This strongly suggests that M6G may act through a novel opioid receptor displaying a distinct pharmacological mechanism.

Prognostic factors of rheumatic mitral stenosis during pregnancy and puerperium

OBJECTIVE

To identify characteristics associated with complications during pregnancy and puerperium in patients with rheumatic mitral stenosis.

METHODS

Forty-one pregnant women (forty-five pregnancies) with mitral stenosis, followed-up from 1991 to 1999 were retrospectively evaluated.

PREDICTOR VARIABLES

the mitral valve area (MVA), measured by echocardiogram, and functional class (FC) before pregnancy (NYHA criteria). Maternal events: progression of heart failure, need for cardiac surgery or balloon mitral valvulotomy, death, and thromboembolism. Fetal/neonatal events: abortion, fetal or neonatal death, prematurity or low birth weight (<2,500 g), and extended stay in the nursery or hospitalization in newborn ICU.

RESULTS

The mean +/- SD of age of the patients was 28.8+/-4.6 years. The eventful and uneventful patients were similar in age and percentage of first pregnancies. As compared with the level 1 MVA, the relative risk (RR) of maternal events was 5.5 (95% confidence interval (CI) =0.8-39.7) for level 2 MVA and 11.4 (95% CI=1.7-74.5) for level 3 MVA. The prepregnancy FC (FC > or = II and III versus I) was also associated with risk for maternal events (RR=2.7; 95% CI=1.4-5.3).MVA and FC were not importantly associated with these events, although a smaller frequency of fetal/neonatal events was observed in patients who had undergone balloon valvulotomy.

CONCLUSION

In pregnant women with mitral stenosis, the MVA and the FC are strongly associated with maternal complications but are not associated with fetal/neonatal events. Balloon mitral valvulotomy could have contributed to reducing the risks of fetal/neonatal events in the more symptomatic patients who had to undergo this procedure during pregnancy.

Predictive value of clinical and electrophysiological variables in patients with chronic chagasic cardiomyopathy and nonsustained ventricular tachycardia

OBJECTIVE

Risk stratification of patients with nonsustained ventricular tachycardia (NSVT) and chronic chagasic cardiomyopathy (CCC).

METHODS

Seventy eight patients with CCC and NSVT were consecutively and prospectively studied. All patients underwent to 24-hour Holter monitoring, radioisotopic ventriculography, left ventricular angiography, and electrophysiologic study. With programmed ventricular stimulation.

RESULTS

Sustained monomorphic ventricular tachycardia (SMVT) was induced in 25 patients (32%), NSVT in 20 (25.6%) and ventricular fibrillation in 4 (5.1%). In 29 patients (37.2%) no arrhythmia was inducible. During a 55. 7-month-follow-up, 22 (28.2%) patients died, 16 due to sudden death, 2 due to nonsudden cardiac death and 4 due to noncardiac death. Logistic regression analysis showed that induction was the independent and main variable that predicted the occurrence of subsequent events and cardiac death (probability of 2.56 and 2.17, respectively). The Mantel-Haenszel chi-square test showed that survival probability was significantly lower in the inducible group than in the noninducible group. The percentage of patients free of events was significantly higher in the noninducible group.

CONCLUSION

Induction of SMVT during programmed ventricular stimulation was a predictor of arrhythmia occurrence cardiac death and general mortality in patients with CCC and NSVT.

Pharmacology of flavor preference conditioning in sham-feeding rats: effects of dopamine receptor antagonists

Opioid and dopamine systems are both implicated in the response to sweet solutions. Our laboratory previously reported that the opioid antagonist, naltrexone, reduced the intake of sweet solutions, yet had little or no effect on sucrose-conditioned flavor preferences in sham-feeding rats. The present study examined the role of dopamine D(1) and D(2) receptors in the expression of flavor preferences conditioned by the sweet taste of sucrose. All sessions were conducted under sham-feeding conditions to minimize postingestive influences. Training was accomplished by adding a novel flavor (CS+) to a 16% sucrose solution, a different flavor (CS-) to a less-preferred 0.2% saccharin solution in alternating, one-bottle sessions. Preferences were assessed in two-bottle tests with the CS+ and CS- flavors presented in mixed sucrose (8%)-saccharin (0.1%) solutions following systemic doses of 0, 50, 200, 400, or 800 nmol/kg of the D(2) antagonist, raclopride (Experiment 1) or the D(1) antagonist, SCH23390 (Experiment 2) under either food-restricted or unrestricted conditions. Rats significantly preferred the CS+ solutions in vehicle tests, and displayed equipotent and dose-dependent reductions in total intake and CS+ preference following either D(1) or D(2) receptor antagonism. Similar results were obtained with SCH23390 and raclopride in Experiment 3 conducted with water-restricted rats. These data indicate that dopaminergic D(1) and D(2) receptors play pivotal and functionally equivalent roles in the expression of flavor preferences conditioned by the sweet taste of sucrose.

Effects of acute and repeated dose administration of caffeine and pentoxifylline on diazepam-induced mouse behavior in the hole-board test

RATIONALE

The behavioral effects of methyl xanthines and their interactions with benzodiazepines have not been clearly established in animal models of anxiety.

OBJECTIVE

The present study extended the previous studies to determine the effects of acute and repeated administration of caffeine, a non-specific phosphodiesterase (PDE) inhibitor and pentoxyfylline, a specific type-4 phosphodiesterase (PDE4) inhibitor on (1) baseline anxiety-like behavior and (2) the response to an acute challenge with diazepam on anxiety-like behavior in the hole-board test.

METHODS

Mice were observed for the number of head-dips they made into the holes of the hole-board apparatus during a 5-min period, starting 30 min after acute (20 mg/kg) and repeated oral dose (20 mg/kg, twice a day for 4 days) administration of caffeine and pentoxifylline. In separate experiments, the response to an acute challenge with graded doses of diazepam (0.375 3 mg/kg, SC) was observed in naive mice or mice on acute and repeated dose regimen with methyl xanthines.

RESULTS

Mice on acute but not after repeated dose regimen demonstrated a significantly increased number of hole-dips, indicating an anxiolytic-like effect of methylxanthines. Diazepam at the lower doses (0.375 and 0.75 mg/kg) but not at the highest doses (1.5 and 3 mg/kg) examined produced a significant anxiolytic-like effect. After an acute dose exposure of mice to caffeine and pentoxifylline, a rightward shift in the dose-response curve of diazepam was observed and particularly at 1.5 mg/kg dose, the net effect of diazepam was significantly enhanced which was, however, impaired upon repeated administration, more so with caffeine than with pentoxifylline.

CONCLUSIONS

It is concluded that the xanthine drugs exert anxiolytic-like activity similar to diazepam in the hole-board test. In addition, they seem to modulate the anxiolytic effects of diazepam after both acute and repeated administration, probably as a result of an endogenous adenosinergic mechanism which may have therapeutic significance.