Attenuation of cardiac hypertrophy by inhibiting both mTOR and NFkappaB activation in vivo

A role for the PI3K/Akt/mTOR pathway in cardiac hypertrophy has been well documented. We reported that NFkappaB activation is needed for cardiac hypertrophy in vivo. To investigate whether both NFkappaB activation and PI3K/Akt/mTOR signaling participate in the development of cardiac hypertrophy, two models of cardiac hypertrophy, namely, induction in caAkt-transgenic mice and by aortic banding in mice, were employed. Rapamycin (2 mg/kg/daily), an inhibitor of the mammalian target of rapamycin, and the antioxidant pyrrolidine dithiocarbamate (PDTC; 120 mg/kg/daily), which can inhibit NFkappaB activation, were administered to caAkt mice at 8 weeks of age for 2 weeks. Both rapamycin and PDTC were also administered to the mice immediately after aortic banding for 2 weeks. Administration of either rapamycin or PDTC separately or together to caAkt mice reduced the ratio of heart weight/body weight by 21.54, 32.68, and 42.07% compared with untreated caAkt mice. PDTC administration significantly reduced cardiac NFkappaB activation by 46.67% and rapamycin significantly decreased the levels of p70S6K by 34.20% compared with untreated caAkt mice. Similar results were observed in aortic-banding-induced cardiac hypertrophy in mice. Our results suggest that both NFkappaB activation and the PI3K/Akt signaling pathway participate in the development of cardiac hypertrophy in vivo.

Involvement of spinal cord nuclear factor κB activation in rat models of proinflammatory cytokine-mediated pain facilitation

Proinflammatory cytokines, such as interleukin-1beta and tumour necrosis factor-alpha, are released by activated glial cells in the spinal cord and play a major role in pain facilitation. These cytokines exert their actions, at least partially, through the activation of the transcription factor, nuclear factor kappaB (NF-kappaB). In turn, NF-kappaB regulates the transcription of many inflammatory mediators, including cytokines. We have previously shown that intrathecal injection of the human immunodeficiency virus-1 (HIV-1) envelope glycoprotein, gp120, induces mechanical allodynia via the release of proinflammatory cytokines. Here, we investigated whether NF-kappaB is involved in gp120-induced pain behaviour in Sprague-Dawley rats. Intrathecal administration of NF-kappaB inhibitors, pyrrolidinedithiocarbamate (PDTC) and SN50, prior to gp120 partially attenuated gp120-induced allodynia. In addition, PDTC delayed and reversed allodynia in a model of neuropathic pain induced by sciatic nerve inflammation. These observations suggest that intrathecal gp120 may lead to activation of NF-kappaB within the spinal cord. To reveal NF-kappaB activation, we assessed inhibitory factor kappaBalpha (IkappaBalpha) mRNA expression by in situ hybridization, as NF-kappaB activation up-regulates IkappaBalpha gene expression as part of an autoregulatory feedback loop. No or low levels of IkappaBalpha mRNA were detected in the lumbar spinal cord of vehicle-injected rats, whereas IkappaBalpha mRNA expression was markedly induced in the spinal cord following intrathecal gp120 in predominantly astrocytes and endothelial cells. Moreover, IkappaBalpha mRNA expression positively correlated with proinflammatory cytokine protein levels in lumbosacral cerebrospinal fluid. Together, these results demonstrate that spinal cord NF-kappaB activation is involved, at least in part, in exaggerated pain states.

Effects of pyrrolidine dithiocarbamate, an NF-kappaB inhibitor, on cytokine expression and ocular inflammation in experimental autoimmune anterior uveitis

AIMS

The aim of this study was to investigate the effects of pyrrolidine dithiocarbamate (PDTC), a nuclear factor (NF)-kappaB inhibitor, on cytokine expression and suppression of anterior chamber inflammation in experimental autoimmune anterior uveitis. Uveitis was induced in the Lewis rats with the injection of a melanin-associated antigen into the peritoneum and footpad. At defined time points, cytokine mRNA expressions in the iris and ciliary body were measured by using a semiquantitative polymerase chain-reaction method.

RESULTS

We found that interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF)-alpha mRNA expression peaked during the active phase of uveitis, whereas interleukin (IL)-10 mRNA increased during the disease resolution. In a separate experiment, PDTC (100 and 200 mg/kg/day) was administrated intraperitoneally daily after immunization. We found that PDTC (100 and 200 mg/kg/day) effectively suppressed ocular inflammation, as indicated by reduced clinical scores and inflammatory cells infiltration in aqueous humor and the iris and ciliary body.

CONCLUSIONS

The inhibitory effects of PDTC are mainly resulted from inhibiting the expression of proinflammatory cytokines, TNF-alpha and IFN-gamma but augmenting anti-inflammatory cytokines, IL-10 expression. These findings suggest that the application of NF-kappaB inhibitors may be a potential therapeutic method for the treatment of acute anterior uveitis.

Effects of beta-Aescin on the expression of nuclear factor-kappaB and tumor necrosis factor-alpha after traumatic brain injury in rats

To investigate the inhibiting effect of beta-Aescin on nuclear factor-kappaB (NF-kappaB) activation and the expression of tumor necrosis factor-alpha (TNF-alpha) protein after traumatic brain injury (TBI) in the rat brain, 62 SD rats were subjected to lateral cortical impact injury caused by a free-falling object and divided randomly into four groups: (1) sham operated (Group A); (2) injured (Group B); (3) beta-Aescin treatment (Group C); (4) pyrrolidine dithocarbamate (PDTC) treatment (Group D). Beta-Aescin was administered in Group C and PDTC treated in Group D immediately after injury. A series of brain samples were obtained directly 6 h, 24 h and 3 d respectively after trauma in four groups. NF-kappaB activation was examined by Electrophoretic Mobility Shift Assay (EMSA); the levels of TNF-alpha protein were measured by radio-immunoassay (RIA); the water content of rat brain was measured and pathomorphological observation was carried out. NF-kappaB activation, the levels of TNF-alpha protein and the water content of rat brain were significantly increased (P<0.01) following TBI in rats. Compared with Group B, NF-kappaB activation (P<0.01), the levels of TNF-alpha protein (P<0.01) and the water content of brain (P<0.05) began to decrease obviously after injury in Groups C and D. Beta-Aescin could dramatically inhibit NF-kappaB activation and the expression of TNF-alpha protein in the rat brain, alleviate rat brain edema, and that could partially be the molecular mechanism by which beta-Aescin attenuates traumatic brain edema.

Stage conversion of Toxoplasma gondii RH parasites in mice by treatment with atovaquone and pyrrolidine dithiocarbamate

The mouse-virulent RH strain of Toxoplasma gondii is generally considered to have lost its cyst-forming capacity, and conversion of RH tachyzoites into cysts in non-immune mice has previously been shown exclusively following early treatment with sulfadiazine (SDZ). We here describe the development of tissue cysts in mice infected with RH strain parasites and treated with atovaquone (ATO) combined with pyrrolidine dithiocarbamate (PDTC). Groups of Swiss-Webster mice infected intraperitoneally (i.p.) with 10(2) RH tachyzoites were treated with 5, 25 and 100 mg of ATO/kg per day alone or combined with PDTC at 250 mg/kg per day from day 1 postinfection (p.i.) for 14 days. A total of 19 mice survived the 6-week observation period. Of these, brain cysts were recovered in nine (47%), with burdens ranging from 50 to 3120 (mean +/- S.D. = 622 +/- 963). All cyst-harboring mice had high specific IgG antibody levels (1:10,240-1:40,960, corresponding to 500-2000 IU/ml), as did one mouse in which cysts were not demonstrated, which was therefore included in the group of mice with residual infection. Bioassay performed to test the infectivity of these cysts produced acute lethal toxoplasmosis following i.p. inoculation in all instances (100%), and importantly, following peroral inoculation in four (29%). The recovered tachyzoites were highly infectious. In addition, significantly elevated interferon gamma (IFN-gamma) in the treated mice which developed residual infection compared with any group of infection-free (treated or subinoculated) mice, indicates immunological control of the parasite in the latent form. In conclusion, early treatment of mice infected with T. gondii RH tachyzoites with ATO and PDTC induces conversion into tissue cysts, thus providing a new model for studying the mechanism(s) of T. gondii stage conversion.

Inhibition of nitrosylation, nitration, lymphocyte proliferation, and gene expression in acute and delayed cardiac allograft rejection by an orally active dithiocarbamate

Dithiocarbamate derivatives sequester metals such as iron and may have benefits in inflammatory diseases. We examined the actions of a new dithiocarbamate-based oral formulation, NOX-700, on protein modification by nitric oxide (NO), gene expression, and lymphocyte proliferation in a model of acute and delayed cardiac rejection. Chronic treatment with NOX-700 prolonged graft survival. In combination with low-dose cyclosporine (CsA), NOX-700 produced a synergistic action to prolong graft survival. NOX-700 decreased myocardial heme nitrosylation. A single bolus injection with NOX-700 in untreated recipients did not decrease heme nitrosylation but normalized NO metabolites and caused the formation of a mononitrosyl iron complex indicating NO scavenging in vivo. NOX-700 alone given with CsA inhibited protein nitration. NOX-700 or CsA each alone decreased intragraft inflammatory cell infiltration. NOX-700 also potentiated the CsA-induced inhibition of splenocyte proliferation ex vivo stimulated by concanavalin A. In splenocytes derived from treated rats but stimulated ex vivo in a mixed lymphocyte response (MLR), interferon-gamma and cyclin D3 gene expression was inhibited by NOX-700 suggesting down-regulation of lymphocyte activation and proliferation by in vivo treatment. These studies suggest that NOX-700 is protective in cardiac rejection, in part, by scavenging of NO and by limiting lymphocyte activation infiltration.

Inhibition of nuclear factor-kappa B prevents staphylococcal enterotoxin A-induced fever

It has been shown that staphylococcal enterotoxin A (SEA) acts through human peripheral blood mononuclear cells (PBMC) to stimulate synthesis or release of pyrogenic cytokines. Nuclear factor-kappa B (NF-kappaB) is thought to play an important role in inflammatory responses through the regulation of genes encoding pro-inflammatory cytokines. The purpose of the present study was to determine whether the NF-kappaB mechanisms in human PBMC are involved in SEA-induced fever. Western blot evaluation revealed SEA was able to induce nuclear translocation of NF-kappaB from cytosol to nucleus in PBMC, which could be abolished by a NF-kappaB inhibitor such as pyrrolidine dithiocarbamate (PDTC), sodium pyrithione (Pyri), N-acetyl-L-cysteine (NAC), or curcumin (Cur). Electrophoretic mobility shift assay also showed that the NF-kappaB DNA-binding activity was increased in the SEA-treated PBMC. Again, the SEA-induced increased NF-kappaB binding activity was significantly attenuated by either PDTC, Pyri, NAC or Cur. The pyrogenic responses to supernatant fluids obtained from human PBMC stimulated with SEA were associated with increased levels of interleukin 1-beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) in the supernatant fluids. Both the fever and the increased levels of IL-1beta, IL-6, and TNF-alpha in supernatant fluids obtained from the SEA-stimulated PBMC were decreased by incubating SEA-PBMC with either PDTC, Pyri, NAC, or Cur. Furthermore, the fever induced by systemic or central administration of SEA in rabbits were attenuated by pre-treatment with an systemic or central dose of either PDTC, Pyri, NAC, or Cur. The data indicate that inhibition of NF-kappaB prevents SEA-induced fever.

Transformation of chloropicrin and 1,3-dichloropropene by metam sodium in a combined application of fumigants

Combined application of fumigants is a potential strategy to replace methyl bromide in the control of soil-borne pests. Unfortunately, abiotic and biotic interactions among fumigants restrict some combined application approaches. In this study, the kinetics and mechanisms of reaction between metam sodium (sodium methyldithiocarbamate) and the halogenated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) were investigated in aqueous solution. For chloropicrin, an extremely rapid oxidation-reduction process occurred in the presence of metam sodium. The second-order rate constant for the reaction between chloropicrin and metam sodium was approximately 2 orders of magnitude greater than that for the reaction between 1,3-D isomers and metam sodium. Transformation of 1,3-D by metam sodium was associated with an aliphatic S(N)2 nucleophilic substitution process. The nucleophilic reaction of cis-1,3-D with metam sodium was significantly faster than that of the trans isomer and was correlated with a lower reaction activation energy for the cis isomer in the transition state. Combining Telone C-35 (65% 1,3-D and 35% chloropicrin) and metam sodium in solution might yield some nucleophilic sulfur species, which played an important role in the dissipation of 1,3-D. The incompatibility of chloropicrin and 1,3-D with metam sodium was also examined in soil under different application scenarios. Simultaneous application of metam sodium with chloropicrin or 1,3-D accelerated the transformation of the two halogenated fumigants, reducing their availability in soil. A sequential strategy for multiple fumigants was developed, which could be applied without the loss of active ingredient that occurs due to the reaction between fumigants. The proposed methodology may enhance pest control while maintaining environmental protection.

A protective effect of pyrrolidine dithiocarbamate in a rat model of liver cirrhosis

BACKGROUND

Nuclear factor kappa B (NF-kappaB) activation, proinflammatory cytokines, and reactive oxygen species have been implicated as mediators of liver injury and fibrogenesis. We have shown recently that pyrrolidine dithiocarbamate (PDTC), an antioxidant and inhibitor of NF-kappaB activation, was protective in a rat model of acute liver failure. The aim of the present study was to examine the efficacy of PDTC in a chronic rat model of thioacetamide (TAA)-induced hepatic fibrosis.

METHODS

Liver cirrhosis was induced by intraperitoneal injections of TAA (200 mg/kg) twice weekly for 12 weeks. Two groups of rats also received PDTC (either 20 or 60 mg/kg, i.p. for 12 weeks).

RESULTS

TAA administration induced liver cirrhosis, which was inhibited by PDTC in a dose-dependent manner. The histopathologic score of fibrosis, the spleen weight, and hepatic hydroxyproline were significantly lower in the rats treated with TAA+PDTC compared with TAA only (P<0.001). The hepatic levels of thiobarbituric acid reactive substances and protein carbonyls after 12 weeks of treatment were also lower in the rats treated with TAA+PDTC (P=0.02 and 0.01, respectively), indicating reduced oxidative stress. Immunohistochemical studies and in situ hybridization demonstrated inhibition of stellate cell (alpha smooth muscle actin positive) activation, tissue inhibitor of metalloproteinase-2, and collagen alpha1(I) gene expression in the livers of the PDTC-treated rats. As determined by Northern blot analysis, PDTC had no inhibitory effect on collagen alpha1(I) gene expression in the rat hepatic stellate cells-T6 cells in vitro.

CONCLUSIONS

PDTC inhibits the development of liver cirrhosis in TAA-treated rats. The mechanism of action is associated with decreased oxidative stress and hepatic necroinflammation.

Evidence for the extrapulmonary localization of inhaled nitric oxide

Inhaled nitric oxide (NO) has emerged as a promising pulmonary vasodilator to treat pulmonary hypertension associated with heart disease and ventilation/perfusion mismatching. However, the pharmacokinetics of inhaled NO still remains obscure and its cardiopulmonary selectivity appears to be increasingly under debate. In the present study measured NO content and levels of cyclic guanosine 3',5'monophosphate (cGMP), a mediator of NO-induced vasodilation, in a variety of organs from rats subjected to NO inhalation. Electron spin resonance spectroscopy associated to a spin trapping technique using N-methyl D-glucamine dithiocarbamate (FeMGD) was used to directly quantify NO levels in the lung, kidney, liver, aorta, and heart from anesthetized Wistar rats subjected to various doses (0, 20, 50, 100, or 200 ppm) and various times (0, 30, 45, or 75 minutes) of inhaled NO. Inhaled NO at a dose of 100 and 200 ppm significantly increased the NO-FeMGD complex in all organs studied. An increase of cGMP was detected in the lung and the aorta after inhaled NO for 45 minutes at the dose of 50 ppm. No changes in NO levels and its metabolites were shown between 30 and 75 minutes of inhaled NO. The results show that inhaled NO at a dose of 100 ppm or more increases NO levels in other organs beside the lung, strongly suggesting that inhaled NO would be more than a pulmonary vasodilator and its selectivity remains to be reconsidered when used for therapeutic purposes.

Spatial distribution and temporal onset of NF-kB activation and inducible nitric oxide synthase within pancreatic islets in the pre-diabetic stage of genetic, diabetic-prone BB rats: attenuation by drug intervention decreases inflammatory cell infiltration and incidence of diabetes

OBJECTIVE AND DESIGN

To document in vivo immunolocalization and activation of nuclear factor-kappaB (NF-kappaB) and inducible nitric oxide synthase (iNOS) expression in prediabetic stages of diabetes mellitus.

MATERIAL OR SUBJECTS

Genetic, diabetic-prone or diabetic-resistant BB rats (total = 189).

TREATMENT

Various doses of an oral dithiocarbamate derivative, NOX-700, or cyclosporine (2.5 mg/kg) starting at 30 or 60 days of age.

METHODS

Immunohistochemistry, electrophoretic mobility shift assays, plasma glucose.

RESULTS

NF-kappaB and iNOS was increased in pancreas of hyperglycemic, diabetic-prone rats but not normoglycemic, diabetic-resistant rats. Immunostaining for NF-kappaB and iNOS was largely confined to islets and occurred in diabetic-prone rats prior to overt hyperglycemia. NOX-700 decreased cell infiltration, delayed the onset of disease and decreased the incidence of hyperglycemia to levels achieved by immunosuppressant therapy. NOX-700 also decreased the intensity of immunoreactive NF-kappaB and iNOS within pancreatic islets.

CONCLUSIONS

These studies support a role of NF-kB and iNOS in diabetogenesis in vivo.

Induction of cyclooxygenase-2 accounts for restraint stress-induced oxidative status in rat brain

Cyclooxygenase (COX) is the rate-limiting enzyme in the metabolism of arachidonic acid into prostanoids. Although it is constitutively expressed in brain neurons, the inducible isoform (COX-2) is also upregulated in pathological conditions such as seizures, ischemia or some degenerative diseases. To assess whether COX-2 is regulated after stress, we have used adult male Wistar rats, some of which were immobilized during 6 h. An increase in PGE2 concentration occurs in brain cortex after 2-6 h of the onset of stress as well as an enhancement of COX-2 protein. Immunohistochemical studies indicate that COX-2 is expressed in the cortex and hippocampus after stress in cells with morphology of neurons. Administration of PDTC (150 mg/kg), an inhibitor of the transcription factor NF-kappaB or MK-801 (0.2 mg/kg), an N-methyl-D-aspartate receptor blocker, prevents both stress-induced increase in COX-2 activity and protein levels, suggesting an implication of these factors in the mechanism by which stress induces COX-2 in brain. To assess if COX-2 accounts for the oxidative status seen in brain after stress, a group of animals were i.p. injected with NS-398, a specific COX-2 inhibitor 1 h prior to the onset of stress. NS-398 (5 mg/kg) decreases stress-induced malondialdehyde accumulation in cortex as well as prevents the stress-induced oxidation of glutathione. Finally, NS-398 reduced Ca2+-independent inducible nitric oxide synthase (iNOS, NOS-2) activity and lowered the stress-induced accumulation of NO metabolite levels in cortex. These effects of NS-398 seem to be due to the specific inhibition of COX-2, since it has no effect on stress-induced corticosterone release, glutamate release, and NF-kappaB activation. These findings are discussed as possible damaging and/or adaptive roles for stress-induced COX-2 in the brain.

Chronic or delayed treatment with an oral dithiocarbamate analog decreases glycation and protects diabetic arteries

In the present study, we examined the efficacy of a dithiocarbamate-based compound, denoted as NOX-700, on diabetes-induced endothelial dysfunction and glycosylation of hemoglobin (Hb). Streptozotocin-induced diabetic rats received 3 mg/ml NOX-700 in drinking water beginning at 72 h or 4 weeks and continued to 8 weeks. Oxidative and glycooxidative stress were examined by electrophoretic mobility shift assay (EMSA) for nuclear factor-kappaB (NF-kappaB) in nuclear fractions of aortic homogenates and by glycosylated Hb, respectively. Vascular reactivity was examined in aortic ring segments ex vivo. Treatment with NOX-700 inhibited glycosylated Hb formation when given long-term or after delayed administration. NOX-700 improved endothelium-dependent relaxation to acetylcholine but did not alter reactivity to norepinephrine or nitroglycerin, suggesting selective protection of the endothelium. Nuclear factor-kappaB (NF-kappaB) nuclear binding activity was significantly increased in diabetic aortas and abrogated by NOX-700. Thus, vascular protection by NOX-700 is believed to be mediated, in part, by an antioxidant mechanism and decreased protein glycation.

Efficacy of the liquid formulation of some nematicides

Bunches of 25 g of tomato galled roots containing ca. 270 eggs and juveniles/g of Meloidogyne incognita were buried on 29 September 2001 in gauze bags at the depth of 15, 30 and 45 cm in a sandy loam. The liquid formulation of the nematicides 1,3 dichloropropene (at the rate of 100, 200 and 300 l/ha), metam sodium (at the rate of 500, 1000, and 1500 l/ha), oxamyl (at the rate of 50, 100 and 150 l/ha) and fenamiphos (at the rate of 30, 60, and 90 l/ha) were then applied in 10, 20 or 40 l/m2 of water. Control plots received only plain water. One month later all bags were recovered and the roots mixed with steamed soil and filled in plastic pots in which two tomato seeds were planted. Fifty days later plants were uprooted and aliquots of roots were macerated in blender to determine the number of eggs and juveniles. 1,3 dichloropropene, metam sodium and oxamyl were equally effective in controlling root-knot nematodes; fenamiphos was less effective. For all chemicals degree of control increased with the increase of rate of application and the volume of water of application, but decreased in the increase of depth of nematode burial.

Blocking NF-κB Activation May Be an Effective Strategy in the Fever Therapy

Lipopolysaccharide (LPS) stimulates peripheral mononuclear cells (PBMC) to synthesize or release pyrogenic cytokines, including interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha). Nuclear factor-kappa B (NF-kappaB) influences inflammatory responses through the regulation of genes encoding cytokines. In the present study, experiments were carried out to determine whether an inhibition of NF-kappaB mechanisms causes an inhibition of pyrogenic cytokine synthesis or release from PBMC and results in antipyresis. Intravenous administration of the supernatant fluids obtained from the human PBMC incubated with LPS caused feverlike hyperthermia in rabbits. The febrile responses were in parallel with the levels of IL-1beta, IL-6, and TNF-alpha in supernatant fluids. Both the fever and the increased levels of these cytokines in supernatant fluids were decreased by incubating LPS-PBMC with NF-kappaB inhibitors, including pyrrolidine dithiocarbamate, sodium pyrithione, N-acetyl-cysteine, and curcumin. Moreover, an intravenous administration of LPS (0.5-2 microg/kg) produced dose-dependent fever in the rabbits. The fevers were in parallel with the levels of IL-1beta, IL-6, and TNF-alpha in rabbit serum. A pretreatment of rabbits with an intravenous injection of pyrrolidine dithiocarbamate, sodium pryithione, N-acetyl-cysteine, or curcumin 1 h before the intravenous administration of LPS significantly attenuated the LPS-induced fever and/or increased levels of these cytokines in the serum of rabbits. Furthermore, pretreatment with an intravenous dose of anti-IL-1beta, anti-IL-6, or anti-TNF-alpha monoclonal antibody significantly attenuated the fever induced by the intravenous injection of LPS in rabbits. The antipyretic effects exerted by anti-L-1beta monoclonal antibody were greater than those exerted by anti-L-6 or anti-NF-alpha monoclonal antibody. The data indicate that NF-kappaB activation correlates with an LPS-induced synthesis or a release of cytokines (in particular, IL-1beta) from PBMC and triggers fever. Blocking NF-kappaB mechanisms in the PBMC with NF-kappaB inhibitors may be an effective strategy in the fever therapy.

Chemical alternatives to methyl bromide for the control of root-knot nematodes in greenhouses

The complete phase-out of methyl bromide from use in developed countries by 1 January 2005 will cause many problems in agricultural industries that are now heavily reliant on its use. Three field experiments were established to compare management tactics on tomato and cucumber in commercial greenhouses naturally infested with root-knot nematodes (Meloidogyne spp). Reduction of nematode juveniles in soil and roots to nil detection levels was observed in all plots following soil fumigation with methyl bromide. A significant reduction of nematode juveniles and root-galling index was observed in plots treated with metham-sodium, dazomet and 1,3-dichloropropene compared with the control and plots treated with non-fumigant nematicides. Reduction of the nematode population led to an increase in fruit yield. However, data collected from the second cultivation season indicated that single control methods such as fumigant or contact nematicides alone cannot drastically decrease initial nematode population and those nematodes which escape control lead to population increase by the end of the cropping season.

Early administration of PDTC in adriamycin nephropathy: effect on proteinuria, cortical tubulointerstitial injury, and NF-kappaB activation

The persistence of NF-kappaB independent inflammatory signals in the cortical tubulointerstitium may explain the incomplete suppression of interstitial monocyte accumulation by the antioxidant NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), in nephrotic rats with established Adriamycin nephropathy (AN). Because PDTC is known to have anti-proteinuric effects, in this study we investigated whether earlier commencement, during the pre-nephrotic phase of AN, would be more effective in reducing interstitial monocyte accumulation. Male Wistar rats with AN received either vehicle or PDTC (50 mg/kg bd i.p.i.) from d7 until d30 (n = 8 per group). On d30, PDTC reduced renal cortical lipid peroxidation (43%), wet kidney weight and tubulointerstitial injury in AN, but did not decrease proteinuria. Accordingly, inhibition of interstitial ED-1 accumulation remained incomplete (52%). Interestingly, the early administration of PDTC in AN, induced polyuria and renal cortical NF-kappaB DNA-binding activity was reduced by only 35%. These results suggest that: (i) the combination of an anti-proteinuric agent with PDTC may be required to completely suppress interstitial monocyte cell accumulation in AN and, (ii) the timing and duration of PDTC therapy are an important determinant of its efficacy to reduce NF-kappaB activation, in vivo.

Developmental toxicity evaluation of 1,2,3,4-butanetetracarboxylic acid in Sprague Dawley (CD) rats

1,2,3,4-butanetetracarboxylic acid (BTCA), proposed as a formaldehyde substitute in the treatment of permanent press fabrics, was evaluated for developmental toxicity. Timed-mated CD rats (25 per group) received BTCA 250, 500, or 1000 mg/kg/day or vehicle (deionized/distilled water) by gavage on gestational days (gd) 6 through 19. Maternal feed and water consumption, body weight, and clinical signs were monitored throughout gestation. At termination (gd 20), confirmed-pregnant females (21 to 25 per group) were evaluated for clinical status and gestational outcome; live fetuses were examined for external, visceral, and skeletal malformations. One maternal death, reduced body weight, and reduced weight gain were noted at the high dose; confirmed pregnancy rates were 84 to 100% for each group. There were no treatment-related effects on fetal growth, survival, or morphologic development. The maternal toxicity NOAEL and LOAEL are 500 and 1000 mg/kg/day, respectively. The developmental toxicity NOAEL is > or = 1000 mg/kg/day, and the LOAEL was not established in this study.

Inhibition of the initial wave of NF-kappaB activity in rat muscle reduces ischemia/reperfusion injury

Nuclear factor kappaB (NF-kappaB) is thought to play an important role in the expression of genes expressed in response to ischemia/reperfusion (I/R) injury. In this report, the activation of NF-kappaB in rat skeletal muscle during reperfusion following a 4-h ischemic period was studied. NF-kappaB activation displayed a biphasic pattern, showing peak activities from 30 min to 3 h postperfusion and 6 h to 16 h postperfusion, with a decline to baseline binding activity levels between 3 h and 6 h. Inhibition of NF-kappaB activation was investigated using proline dithiocarbamate (Pro-DTC). NF-kappaB binding activity during reperfusion was significantly reduced by intravenous administration of Pro-DTC. Additionally, Pro-DTC resulted in decreased muscle edema and neutrophil activity, with an increased percentage of muscle survival compared with vehicle controls. These results demonstrate that NF-kappaB is activated during reperfusion in a biphasic manner and that the regulation of the initial phase of NF-kappaB activation affords physiological protection against a severe ischemic stress. Selective inhibition of NF-kappaB during early reperfusion may therefore be a therapeutic intervention for I/R injury.

Optimum timing of insecticide applications against diamondback moth Plutella xylostella in cole crops using threshold catches in sex pheromone traps

Field trials were conducted in cabbage (Brassica oleracea var capitata), cauliflower (B oleracea var botrytis) and knol khol (B oleracea gongylodes) crops at two different locations in Karnataka State (India) to optimize the timing of insecticide applications to control the diamondback moth, Plutella xylostella, using sex pheromone traps. Our results indicate that applications of cartap hydrochloride as insecticide during a 12-24 h period after the pheromone traps had caught on average 8, 12 and 16 males per trap per night in cabbage, cauliflower and knol khol, respectively, were significantly more effective than regular insecticide sprays at 7, 9, 12 or 15 days after transplantation. This was demonstrated by estimation of the mean number of eggs and larvae per plant, the percentage of holes produced, as well as the marketable yield of the three crops at each location. A good correlation between the immature stages, infestation level, the estimated crop yield and the number of moths caught in pheromone traps was also found, indicating the usefulness of pheromone-based monitoring traps to predict population densities of the pest.

Synergistic antiinflammatory effect of NF-kappaB inhibitors and steroidal or non steroidal antiinflammatory drugs in the pleural inflammation induced by carrageenan in mice

OBJECTIVES

Experiments were designed to determine whether or not inhibitors of NF-Kappa B (NF-kappaB) exhibit antiinflammatory effects when assessed in carrageenan-induced pleural inflammation in the mouse.

MATERIAL AND METHODS

Adult mice of both sexes received pyrrolidine dithiocarbamate (PDTC) or sulfasalazine administered intraperitoneal by at several time points before intrapleural injection of carrageenan (1%) and the exudation and the total and differential cells were analysed.

RESULTS

PDTC or sulfasalazine largely and almost completely inhibited the leukocyte infiltration and the exudation induced by intrapleural administration of carrageenan, when assessed 4 h (but not 48 h) after carrageenan injection. The combination of subliminal doses of PDTC or sulfasalazine with steroidal (dexamethasone) or non-steroidal (indomethacin, meloxicam, nabumetone, diacerein) antiinflammatory drugs, which alone had no antinflammatory action, greatly inhibited both the pleural cell infiltration and exudation induced by carrageenan. The highest inhibition of leukocyte infiltration was observed with the combination of PDTC or sulfasalazine with dexamethesone (84 and 75%, respectively).

CONCLUSIONS

These results indicate that nuclear factor-kappaB might play an important role in the modulation of the early phase of the pleural inflammatory response induced by carrageenan in the mouse. Furthermore, our results demonstrate for the first time a marked synergistic interaction among dexamethasone--and to a lesser extent among nonsteroidal antiinflammatory drugs--and the NF-kappaB inhibitors, suggesting that this association may be of potential interest for the management of certain inflammatory processes, including asthma therapy.

Long-term treatment in vivo with NOX-101, a scavenger of nitric oxide, prevents diabetes-induced endothelial dysfunction

Substantial evidence exists that diabetes results in impaired endothelial dysfunction suggesting diminished nitric oxide production from diabetic endothelium. It is not known what factors contribute to the development of this defect. In this study, we tested whether chronic treatment in vivo with NOX-101, a water-soluble nitric oxide scavenger, prevents endothelial dysfunction in diabetes. Sprague-Dawley rats were made diabetic by an intravenous injection of streptozotocin. A subgroup of control or diabetic animals received twice daily subcutaneous injections of 80 mg/kg NOX-101 beginning at 48 h after streptozotocin was injected and throughout 8 weeks of diabetes. Body weights and glucose concentrations were monitored weekly. At the end of 8 weeks, blood glucose and glycosylated haemoglobin was raised in diabetic rats but serum insulin concentrations were reduced. Treatment with NOX-101 did not alter glucose or insulin concentrations in control or diabetic rats; however, total glycosylated haemoglobin was partially reduced compared with untreated rats. In a subgroup of 2-week diabetic and age-matched rats fasted for 24 h, NOX-101 abolished total urinary nitrate plus nitrite (an index of nitric oxide production in vivo). In isolated tissue baths, relaxation to the endothelium-dependent vasodilator, acetylcholine, was impaired in diabetic aortic rings and relaxation to nitroglycerin was unaltered. Treatment of control rats with NOX-101 did not alter maximum relaxation to acetylcholine but shifted the response curve slightly to the right. In contrast in diabetic rats, NOX-101 prevented the impairment in endothelium-dependent relaxation but had no effect on relaxation induced by nitroglycerin. These data suggest the possibility that diabetes-induced endothelial dysfunction in diabetes results, in part, from a paradoxical increase in nitric oxide production during the course of the disease. This suggests a novel pathway of vascular complications.

Electron spin resonance analysis of heme-nitrosyl and reduced iron-sulfur centered complexes in allogeneic, heterotopic cardiac transplants: effects of treatment with pyrrolidine dithiocarbamate

Inhibition of inducible nitric oxide synthase (iNOS) prolongs allograft survival suggesting a role for nitric oxide (.NO) in allograft rejection. Induction of iNOS is regulated by the oxidant-sensitive, nuclear factor kappa B (NF-kappaB) in many cell types. In the present study using electron spin resonance (ESR) spectroscopy, we evaluated whether pyrrolidine dithiocarbamate (PDTC), a metal chelator and antioxidant, might limit .NO production during the development of rejection in cardiac allografts. We performed either isogeneic (Lewis to Lewis) or allogeneic (Wistar-Furth to Lewis) heterotopic abdominal cardiac transplantation. Allograft recipients received daily injections of PDTC or aminoguanidine (a known inhibitor of iNOS). At postoperative days 4 or 6, grafted and native hearts of transplant recipients were flushed with cardioplegic solution to remove blood contamination. ESR data of allografts revealed a triplet nitrogen signal (aN=17.5 G) and centered at g=2.012 and an additional broad signal at g=2.08. This signal was not seen in either isografts or native hearts of either isograft or allograft recipients. Based upon these parameters, these signals are attributed to nitrosomyoglobin. This signal was inhibited by treatment with aminoguanidine or PDTC. Under these conditions, PDTC also prolonged graft survival from 6.6+/-0.2 to 11.7+/-0.3 days. Thus, it is conceivable that nitrosylmyoglobin formation precedes rejection in cardiac allografts and inhibition of nitrosomyoglobin with agents such as PDTC contribute to improved graft survival.

H2O2 is an important mediator of UVB-induced EGF-receptor phosphorylation in cultured keratinocytes

Exposure of human keratinocytes to physiologic doses of ultraviolet B (UVB) radiation induces phosphorylation of the epidermal growth factor receptor (EGFR). We demonstrate that H2O2 generated by UVB mediates EGFR phosphorylation. Using dihydrorhodamine 123 as a specific fluorescent dye probe, we show that UVB irradiation (50-800 J per m2) of keratinocytes leads within minutes to concentration-dependent intracellular production of H2O2. A corresponding concentration-dependent increase in the release of extracellular H2O2 was measured by using Amplex, a derivative of dihydrophenoxazine. The levels of intracellular H2O2 that are induced by UVB irradiation and that stimulate EGFR phosphorylation correlate strongly with the response induced by exogenously added H2O2. UVB or H2O2 demonstrated concentration- and time-dependent stimulation of EGFR phosphorylation that was initially observed within 1-5 min and exhibited a proportionate delay for UVB-induced production of H2O2. EGFR phosphorylation induced by UVB or H2O2 declined significantly toward baseline levels by 4 h and could be restimulated after H2O2 but not after UVB exposure. Phosphorylation of EGFR was inhibited by the structurally unrelated antioxidants butylated hydroxyanisole, N-acetyl-L-cysteine, and pyrrolidine dithiocarbamate, or by the H2O2-degrading enzyme catalase. These data indicate that generation of H2O2 by UVB radiation of human keratinocytes participates in the rapid, ligand-independent phosphorylation of EGFR and implicate H2O2 as a biologic mediator in EGFR activation and regulation of the downstream signaling cascade. UVB-induced H2O2 has the potential to initiate or modulate early EGFR-mediated signaling events that could play an important role in the cellular response to oxidative stress.