A comparative study of central versus posterior approach for internal jugular hemodialysis catheter insertion.

Internal jugular (IJ) catheter insertion for hemodialysis (HD) is an indispensable procedure in the management of patients with renal failure. The central approach is favored over posterior approach to insert IJ catheters. There are no studies comparing the outcomes between the two approaches. The aim of this study was to compare central approach with posterior approach for IJ HD catheter insertion and to analyze various outcomes like procedure-related complication rates, catheter insertion failure rates, interruptions during dialysis due to blood flow obstruction and catheter infection rates between the two methods among patients receiving HD. All patients requiring IJ HD catheter insertion during a 1-month period were randomly assigned to undergo catheter insertion via either conventional central approach or posterior approach. Patients were followed-up till the removal of the catheter. Among 104 patients included in the study, 54 were assigned to the central approach group and 50 to the posterior approach group. The central approach group had higher rate of procedure-related complications (14.81% vs. 6%, P = 0.04). Catheter insertion failure rates were marginally higher in posterior approach group (20% vs. 12.96%, P = 0.07). One or more instance of interruption during HD due to obstruction in blood flow was more common in posterior approach (46% vs. 9.25%, P < 0.01). Catheter infection rates were similar between the two groups; 16.66% (n = 9) in central group vs. 14% (n = 7) in posterior group. Posterior approach is a reasonable alternative to conventional central approach in IJ cannulation for HD catheter. It is, however, associated with a significantly high rate of interruption in HD blood flow and catheter insertion failure rates. The posterior approach can be used in patients with local exit site infection or in failed attempts to cannulate IJ vein via the conventional central approach.

Enraizamento in vitro de catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza), uma planta medicinal do Cerrado / Study on the in vitro rooting of Anemopaegma arvense (Vell. ) Stell. ex de Souza, a medicinal plant of the Brazilian Cerrado

Este trabalho foi realizado com o objetivo de otimizar o protocolo para enraizamento in vitro de Anemopaegma arvense, planta medicinal do Cerrado em risco de extinção e conhecida popularmente como catuaba, a qual é amplamente utilizada na medicina popular. Brotações cultivadas in vitro foram inoculadas em meio de cultura MS/2 liquido e MS sólido suplementado com diferentes concentrações de auxinas, poliaminas ou dithiothreitol (DTT). As avaliações foram realizadas quanto à porcentagem de enraizamento, número e comprimento das raízes. A presença de NAA (Ácido naftaleno acético) no meio de cultura foi essencial para promover a indução de raízes adventícias nas brotações. A maior porcentagem de enraizamento, 50%, foi obtida no tratamento 2 mg L-1 de NAA com tempo de permanência de 15 dias nesta auxina. No experimento com poliaminas o melhor tratamento foi MS/2 + 5 mg L-1 de putrescina, com 27% de brotações enraizadas. Na presença de DTT (Dithiothreitol), 23% das brotações enraizaram em 0,10 mg L-1 de DTT. A presença da auxina NAA e a alternância no tempo de permanência foi a melhor condição para promover o enraizamento in vitro da de A. arvense. .

This work was carried out in order to optimize an efficient protocol for the in vitro rooting of Anemopaegma arvense, a medicinal plant of the Brazilian Cerrado in danger of extinction, popularly known as Catuaba in Portuguese and widely used in folk medicine. Shoots cultivated in vitro were inoculated in liquid MS/2 and solid MS culture medium supplemented with different concentrations of auxins, polyamines or dithiothreitol (DTT). Evaluations were performed for the rooting percentage and for the number and length of roots. The presence of NAA (naphthaleneacetic acid) in the culture medium was essential to promote the induction of adventitious roots. Higher rooting percentage (50%) was obtained in the treatment with 2 mg L-1 NAA and duration of stay of 15 days in this auxin. In the experiment with polyamines, the best treatment was MS/2 + 5 mg L-1 putrescine with 27% of shoots rooted. In the presence of DTT (dithiothreitol), 23% of shoots rooted at 0.10 mg L-1 DTT. The presence of the auxin NAA and the alternation in length of stay was the best condition to promote in vitro rooting of A. arvense. .

Evaluation of renal protection from high doses of melatonin in an experimental model of renal ischemia and reperfusion in hyperglycemic rats.

BACKGROUND: Melatonin is a free radical scavenger with important actions in the study of renal ischemia and reperfusion (I/R). This study evaluated possible renal protection of high doses of melatonin in an experimental model of I/R in which rats were submitted to acute hyperglycemia under anesthesia with isoflurane. METHOD: Forty-four male Wistar rats, weighing more than 300 g, were randomly divided into 5 groups: G1, sham (n = 10); G2, melatonin (n = 10; 50 mg.kg(-1)); G3, hyperglycemia (n = 9; glucose 2.5 g.kg(-1)); G4, hyperglycemia/melatonin (n = 10; 2.5 g.kg(-1) glucose + melatonin 50 mg.kg(-1)); and G5, I/R (n = 5). In all groups, anesthesia was induced with 4% isoflurane and maintained with 1.5% to 2.0% isoflurane. Intraperitoneal injection of melatonin (G1, G4), glucose (G3, G4), or saline (G1, G5) was performed 40 minutes before left renal ischemia. Serum plasma values for creatinine and glucose were determined at baseline (M1), immediately following reperfusion (M2), and 24 hours after completion of the experiment (M3). Histological analysis was performed to evaluate tubular necrosis (0-5). RESULTS: Serum glucose was higher at M2 in the groups supplemented with glucose, hyperglycemia (356.00 ± 107.83), and hyperglycemia/melatonin (445.3 ± 148.32). Creatinine values were higher at T3 (P = .0001) for I/R (3.6 ± 0.37), hyperglycemia/melatonin (3.9 ± 0.46), and hyperglycemia (3.71 ± 0.69) and lower in the sham (0.79 ± 0.16) and melatonin (2.01 ± 1.01) groups, P < .05. Histology showed no necrosis injury in the G1, lesion grade 2 in the G2, and severe acute tubular necrosis in the G3: (grade 4), G4: (grade 5) and G5: (grade 4) groups (P < .0001). DISCUSSION: Melatonin protected the kidneys submitted to I/R in rats without hyperglycemia; however, this did not occur when the I/R lesion was associated with hyperglycemia. CONCLUSIONS: Due to its antioxidant and antiapoptotic action, melatonin was able to mitigate, but not prevent acute tubular necrosis in rats with hyperglycemia under anesthesia by isoflurane.

Ocorrência de fungos micorrízicos em catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza - Bignoniaceae), uma planta medicinal do Cerrado em risco de extinção / Michorrizical funghi studies in catuaba (Anemopaegma arvense (Vell. ) Stell. ex de Souza), a medicinal plant from the Cerrado region at risk of extinction

Este trabalho foi realizado com o objetivo de verificar a ocorrência de fungos micorrízicos, identificar suas espécies, e avaliar a colonização em raízes de plantas de diferentes populações e variedades de Anemopaegma arvense, uma planta medicinal do Cerrado em risco de extinção. As avaliações da colonização micorrízica e identificação de espécies de fungos micorrízicos arbusculares (FMAs) foram realizadas no Laboratório de Microbiologia do Solo da Universidade Federal de Lavras (UFLA). Foram utilizadas raízes de 10 plantas coletadas em diferentes locais juntamente com as amostras de solo próximo ao sistema radicular de populações naturais das variedades: glabra, puberula e petiolata. Os esporos foram extraídos do solo por meio da metodologia de peneiramento úmido e, para a avaliação e observação da colonização radicular, as raízes coradas foram observadas em microscópio estereoscópico (ampliação 10 a 40x). Em todas as amostras analisadas foi possível identificar espécies de FMAs, exceto para a variedade puberula, coletada no município de Mogi Guaçu-SP. O número de esporos variou de maneira significativa entre as amostras e os locais amostrados, não havendo distribuição regular. Acaulospora scrubiculata, A. spinosa, A. longula, Escustelospora heterogama, Paraglomus occultum, Gigaspora margarita, Gigaspora sp., dentre outros, encontram-se entre as espécies identificadas. Quanto à avaliação da colonização micorrízica nas raízes, observou-se que todas as variedades foram colonizadas no sitema radicular, verificada por meio da presença de hifas. No entanto, a colonização não foi constatada em todas as amostras avaliadas e também não foi observada a formação de arbúsculos e/ou vesículas.

This work was carried out to verify the occurrence, identify species of mycorrhizal fungi and to evaluate the colonization in roots of plants of different varieties and populations of Anemopaegma arvense, a medicinal plant from the Savannah, in danger of extinction. Assessments of mycorrhizal infection and identification of species of mycorrhizal fungi (AMF) were conducted at the Laboratory of Soil Microbiology, Federal University of Lavras (UFLA). We used roots from 10 plants collected at different sites, along with samples of soil near the root system of natural populations of the varieties glabra, puberula and petiolata. Spores were extracted from soil by the wet sifting methodology and, for the assessment and observation of the root colonization, the stained roots were observed under a stereomicroscope (magnification 10 to 40x), respectively. In all samples it was possible to identify AMF species, except for the variety puberula, collected in the municipality of Mogi Guaçu - SP. The number of spores varied significantly between samples and sampling sites, with no regular distribution. Acaulospora scrubiculata, A. spinosa, A. longula, Escustelospora heterogama, Paraglomus occultum, Gigaspora margarita, Gigaspora sp. among others, are some of the species identified. Regarding the assessment of mycorrhizal infection in the roots, we observed that all the varieties analyzed showed colonization by hyphae. However, not all samples assessed presented colonization and the formation of arbuscules and/or vesicles was not observed.

Caffeic acid phenethyl ester effects in the kidney during ischemia and reperfusion in rats anesthetized with isoflurane.

BACKGROUND: The purpose of this investigation was to examine the effect of caffeic acid phenethyl ester (CAPE) in renal ischemia/reperfusion injury in rats anesthetized with isoflurane (iso). METHODS: We randomly assigned 26 male Wistar rats anesthetized with isoflurane, intubated and mechanically ventilated to 3 groups: G1 (controls; n = 8), G2 (CAPE; n = 10), and G3 (ethanol; n = 8). Mean arterial pressure was monitored for anesthetic control. Intraperitoneal CAPE (G2) or ethanol (G3) injections were administered 40 minutes before left renal ischemia. All animals underwent right nephrectomy and the left kidney was submitted to ischemia for 25 minutes. Serum creatinine (cr) values were determined at the beginning (M1), end (M2), and 24 hours after the experiment (M3) upon intracardiac blood samples. The left kidney was removed for histologic analysis, using a scale for tubular necrosis (0-5, injury maximum). Statistical analysis was applied to serum creatinine and histological score injury considering statistical differences to be significant when P < .05. RESULTS: The cr values in the CAPE were significantly higher at M2 (0.8 mg/mL; P = .0012) and M3 (3.7 mg/mL; P = .0014) than the control (0.5 and 0.9 mg/mL) or G3 (0.6 and 1.0 mg/mL), respectively. Histologic examination showed the CAPE group to display more pericapsular tubular necrosis (3.0 [2.0; 3.0]) than the G1 group (2.0 [1.0; 2.0]) or G3 group (1.5 [1.0; 2.0]; P < .001). The CAPE group displayed more medullary tubular necrosis (2.0 [2.0; 3.0] than G1 (2.0 [1.0; 2.0] or G3 (1.0 [0.0; 2.0]; P < .001). CONCLUSION: CAPE promoted greater functional and anatomic renal injury when rats were anesthetized with iso than control or ethanol groups, as demonstrated by histologic analysis and serum values.

Erythropoietin attenuates apoptosis after ischemia-reperfusion-induced renal injury in transiently hyperglycemic Wister rats.

BACKGROUND: Hyperglycemia is associated with a decreased tolerance to ischemia and an increased severity of renal ischemia reperfusion (I/R) injury. It has been suggested that erythropoietin (EPO) attenuates this effect in normoglycemic animals. This study sought to examine the effects of EPO on treatment renal I/R injury (IRI) in transiently hyperglycemic rats. MATERIAL AND METHODS: Twenty-eight male Wister rats anesthetized with isoflurane received glucose (2.5 g.kg(-1) intraperitoneally) before right nephrectomy. They were randomly assigned to four groups: sham operation (S); IRI (ISO); IRI+EPO, (600 UI kg(-1) low-dose EPO [EL]); and IRI+EPO 5000 UI kg(-1) (high-dose EPO [EH]). IRI was induced by a 25-minute period of left renal ischemia followed by reperfusion for 24 hours. Serum creatinine and glucose levels were measure at baseline (M1), immediately after the ischemic period (M2), and at 24 hours after reperfusion (M3). After sacrificing the animals, left kidney specimens were submitted for histological analysis including flow cytometry to estimate tubular necrosis and the percentages of apoptotic, dead or intact cells. RESULTS: Scr in the ISO group was significantly higher at M3 than among the other groups. Percentages of early apoptotic cells in ISO group were significantly higher than the other groups. Percentages of late apoptotic cells in S and ISO groups were significantly greater than EL and EH groups. However, no significant intergroup differences were observed regarding the incidence of tubular necrosis. CONCLUSIONS: Our results suggested that, although not preventing the occurrence of tubular necrosis, EPO attenuated apoptosis and glomerular functional impairment among transiently hyperglycemic rats undergoing an ischemia/reperfusion insult.

Conservação e enraizamento in vitro de infalível (Mandevilla velutina K. Schum.), uma planta medicinal do Cerrado / In vitro conservation and rooting of "infalível" (Mandevilla velutina K. Schum.), a medicinal plant of Cerrado

Mandevilla velutina (Apocynaceae) é uma planta medicinal endêmica do Cerrado brasileiro conhecida popularmente como infalível, utilizada pela população em tratamentos de processos inflamatórios e acidentes com serpentes. Atualmente, esta espécie encontra-se em risco de extinção, devido à coleta extrativista. Os objetivos deste trabalho foram otimizar o protocolo para o enraizamento in vitro de M. velutina e introduzir diferentes genótipos em banco de germoplasma in vitro, a fim de se estabelecer a conservação da espécie. Foram realizados cinco experimentos de enraizamento in vitro utilizando ANA, AIB, di e poliaminas, dithiothreitol e floroglucinol. As avaliações foram realizadas aos 30 e 60 dias quanto à porcentagem de enraizamento, número e comprimento de raiz. Para a introdução dos genótipos in vitro, foram utilizados segmentos nodais (1 cm) como explantes, contendo uma gema axilar ou apical, coletados de plantas mantidas em casa de vegetação, submetidos previamente à assepsia. As avaliações foram realizadas durante quatro semanas, quanto à porcentagem de contaminação dos explantes. Os resultados obtidos nas avaliações evidenciaram que a presença de compostos fenólicos no meio de cultura foi importante na promoção do enraizamento adventício in vitro de M. velutina e a metodologia de assepsia para a introdução de diferentes genótipos in vitro foi eficiente.

Mandevilla velutina (Apocynaceae) is a medicinal plant endemic to the Brazilian Cerrado, commonly known as "infalivel" and used by the population for treatments of inflammatory processes and accidents with snakes. This species is currently endangered due to extraction. The aims of this study were to optimize the protocol for in vitro rooting of M. velutina and to introduce different genotypes in the in vitro germplasm bank to establish the species conservation. Five experiments for in vitro rooting were conducted using NAA, IBA, di and polyamines, dithiothreitol and phloroglucinol. Evaluations were performed at 30 and 60 days as to rooting percentage, and root number and length. For the introduction of genotypes in vitro, nodal segments (1 cm) were used as explants; they had an axillary or apical bud and were collected from plants kept in a greenhouse after being subjected to asepsis. Evaluations were carried out for four weeks as to the percentage of explant contamination. Results showed that the presence of phenolic compounds in the culture medium was important to promote in vitro adventitious rooting in M. velutina and that the asepsis methodology for the introduction of in vitro of different genotypes was efficient.

An unusual gangrenous goat mastitis caused by Staphylococcus aureus, Clostridium perfringens and Escherichia coli co-infection

Relata-se, pela primeira vez no Brasil, a ocorrência de mastite gangrenosa caprina atípica causada pela co-infecção por Staphylococcus aureus, Clostridium perfringens e Escherichia coli em uma cabra da raça Boer, na segunda semana de lactação. Descrevem-se os achados clínicos, os procedimentos de diagnóstico microbiológico e a conduta terapêutica.

Investigation of determinism in heart rate variability.

The article searches for the possible presence of determinism in heart rate variability (HRV) signals by using a new approach based on NARMA (nonlinear autoregressive moving average) modeling and free-run prediction. Thirty-three 256-point HRV time series obtained from Wistar rats submitted to different autonomic blockade protocols are considered, and a collection of surrogate data sets are generated from each one of them. These surrogate sequences are assumed to be nondeterministic and therefore they may not be predictable. The original HRV time series and related surrogates are submitted to NARMA modeling and prediction. Special attention has been paid to the problem of stationarity. The results consistently show that the surrogate data sets cannot be predicted better than the trivial predictor-the mean-while most of the HRV control sequences are predictable to a certain degree. This suggests that the normal HRV signals have a deterministic signature. The HRV time series derived from the autonomic blockade segments of the experimental protocols do not show the same predictability performance, albeit the physiological interpretation is not obvious. These results have important implications to the methodology of HRV analysis, indicating that techniques from nonlinear dynamics and deterministic chaos may be applied to elicit more information about the autonomic modulation of the cardiovascular activity. (c) 2000 American Institute of Physics.

Long-term carcinogenicity of pan masala in Swiss mice.

Carcinogenicity of pan masala, a dry powdered chewing mixture of areca nut, catechu, lime, spices and flavoring agents was evaluated by means of the long-term animal bio-assay 6- to 7-week old male and female S/RVCri mice were divided randomly into intermediate and lifetime exposure groups and fed normal diet without pan masala-(zero dose) or diet containing 2.5% and 5% pan masala. Animals in the intermediate-exposure group (n = 10/gender/dose group) were killed after 6, 12 or 18 months of treatment, while those in the lifetime-exposure group (n = 54/gender/dose group) were killed when moribund or at the termination of the experiment at 24 months. Several tissues were processed for histopathological examination. The body weight and survival rate of mice fed pan masala were lower than that of the controls. Histopathological observations of tissues from control animals did not reveal any neoplastic alterations. However, lifetime feeding of pan masala induced adenoma of the liver, stomach, prostate and sebaceous glands, also forestomach papilloma, liver hamartoma, hepatoma and hemangioma, carcinoma of the forestomach, adenocarcinoma of the lung and liver, and testicular lymphoma. Neoplastic lesions appeared mainly in the liver (n = 13), stomach (n = 3) and lung (n = 8). Lung adenocarcinoma, the most frequent malignant tumor type, was observed in 2/120 mice in the intermediate-exposure group and in 8/216 animals in the lifetime-exposure group. Statistical analysis of tumor-induction data revealed a significant dose-related increase in lung adenocarcinomas but not in liver and stomach neoplasms indicating that lung is the major target tissue for the carcinogenic action of pan masala.

Nonlinear multivariable modeling and analysis of sleep apnea time series.

This paper investigates the modeling and analysis of physiological data recorded from a 49-year-old male and are composed of three time series: blood oxygen saturation, heart rate and respiration. In particular, it is desired to verify if the models estimated from data can distinguish between the dynamics underlying two different breathing patterns (normal breathing and apnea). The estimated models are nonlinear autoregressive, moving average with exogenous inputs (NARMAX) and the regressors used to compose such models are carefully chosen, among hundreds of candidates, by an automatic procedure. The results discussed in this paper suggest that the dynamics underlying the data are nonlinear and basically deterministic. Using estimated models it seems to be possible to quantify the stability of the fixed point in phase space reconstructed using the blood oxygen time series. This, as discussed, could be the basis of an algorithmic monitoring system.

Urate synthesis in the blood-sucking insect rhodnius prolixus. Stimulation by hemin is mediated by protein kinase C.

Hemin is a catalyst of the formation of reactive oxygen species. We proposed that hematophagous insects are exposed to intense oxidative stress because of hemoglobin hydrolysis in their midgut (Petretsky, M. D., Ribeiro, J. M. C., Atella, G. C., Masuda, H., and Oliveira, P. L. (1995) J. Biol. Chem. 270, 10893-10896). We have shown that hemin stimulates urate synthesis in the blood-sucking insect Rhodnius prolixus (Graça-Souza, A. V., Petretsky, J. H., Demasi, M., Bechara, E. J. H., and Oliveira, P. L. (1997) Free Radical Biol. Med. 22, 209-214). Once released by fat body cells, urate accumulates in the hemolymph, where this radical scavenger constitutes an important defense against blood-feeding derived oxidative stress. Incubation of Rhodnius fat bodies with okadaic acid raises the level of urate synthesis, suggesting that urate production can be controlled by protein phosphorylation/dephosphorylation. Urate synthesis is stimulated by dibutyryl cAMP and inhibited by N(2((p-bromocinnamil)amino)ethyl)-5-isoquinolinesulfonamide (H-89), an inhibitor of protein kinase A, as well as activated by the protein kinase C activator phorbol 12-myristate 13-acetate. In the presence of hemin, however, inhibition of urate synthesis by H-89 does not occur, suggesting that the hemin stimulatory effect is not mediated by protein kinase A. Calphostin C completely inhibits the hemin-induced urate production, suggesting that the triggering of urate antioxidant response depends on protein kinase C activation. This conclusion is reinforced by the observation that in fat bodies exposed to hemin, both protein kinase C activity and phosphorylation of specific endogenous polypeptides are significantly increased.

Evaluation of carcinogenic/co-carcinogenic activity of a common chewing product, pan masala, in mouse skin, stomach and esophagus.

Pan masala, a dry powdered mixture of areca nut, catechu, lime, unspecified spices and flavoring agents, has gained widespread popularity as a chewing substitute in India. In this study, the carcinogenic and tumor-promoting potential of an ethanolic pan masala extract (EPME) was determined using skin of S/RVCri-ba mice and forestomach and esophagus of ICRC mice as the target tissues. Carcinogenic activity of pan masala was tested by painting the mouse skin for 40 weeks with EPME or by gavage feeding for 6 months. Following initiation with 9,10-dimethylbenz(a)anthracene (DMBA), carcinogenesis of mouse skin was promoted with different doses of EPME, while gastric- and esophageal-tumor-promoting activity was determined by administering EPME by gavage to animals initiated with diethylnitrosamine (DEN). The ability of EPME to effect progression of skin papilloma to carcinoma and cutaneous alterations after a single or multiple EPME treatment were also evaluated. EPME at 25 mg per dose promoted skin-papilloma formation between 30 and 40 weeks of treatment and enhanced the rate of conversion of papilloma to carcinoma. Induction of mild epidermal hyperplasia, dermal edema, increase in epidermal mitotic activity and the rate of epidermal and dermal DNA synthesis by EPME correlated well with its skin-tumor-promoting potential. In ICRC mice, EPME was inactive as a complete carcinogen, but effectively promoted the development of forestomach and esophageal papilloma and carcinoma in a concentration-dependent manner. The tumor incidence at 25 mg EPME per dose was comparable with that obtained in the 12-O-tetradecanoylphorbol-13 acetate(TPA)-treated group. The findings indicate that habitual pan-masala use may exert carcinogenic and co-carcinogenic influence.

Urate protects a blood-sucking insect against hemin-induced oxidative stress.

Urate at high concentrations (up to 5 mM) is found in the hemolymph of the blood-sucking bug, Rhodnius prolixus. Increased urate levels are observed in the days following a blood meal. Injecting hemin into the hemocoel increases both urate titer and TBARS formation in the hemolymph. The urate response to hemin injection seems to arise from increased synthesis by the fat body as urate secretion by this organ is stimulated in vitro by incubation with hemin, and markedly counteracted by allopurinol. Allopurinol injection also results in increased TBARS formation in the hemolymph. High O2 atmospheric conditions also increases hemolymph urate levels, confirming that urate release represents an antioxidant response. Urate concentrations at the range reported here might account for almost all free radical scavenging activity of the hemolymph, as deduced from TRAP assay experiments, indicating that this is the major low molecular weight protection of this insect against oxidative insult. Since large amounts of hemin are produced in the midgut following blood digestion, increased urate hemolymph levels are suggested to be an important protective biochemical adaptation to allow blood feeding.

Indirect effects of oral tolerance in mice.

Anti-DNP antibody formation resulting from intraperitoneal (i.p.) immunization with DNP-KLH may be blocked by simultaneous (i.p.) injection of DNP-Ova or native Ova in mice orally tolerant to Ova, but not in normal mice. In Ova-tolerant mice the inhibition of anti-DNP antibody formation also occurred when DNP-Ova and DNP-KLH were given by separate routes of immunization: subcutaneous (s.c.) and i.p. A second exposure to Ova by gastric intubation (gavage) or intravenous administration simultaneously with i.p. immunization with DNP-KLH failed to inhibit anti-DNP antibody formation. There was inhibition of responses to DNP-KLH i.p. by DNP-Ova given 24 h before, but not 24 h after, and in the Ova-tolerant mice, addition of DNP-Ova only to the primary immunization with DNP-KLH inhibited secondary and tertiary responses to DNP-KLH in the absence of further exposures to DNP-Ova. These results suggest that the indirect effects of parenteral exposure of tolerant mice to the tolerated immunogen may inhibit unrelated immune responses. This inhibition is not due to 'innocent bystanding' suppression, i.e., to inhibitory cytokines provided locally by specific suppressor lymphocytes; it may derive from more durable perturbations of immune system.

Mutagenicity and carcinogenicity of tea, Camellia sinensis.

Aqueous, caffeine free and tannin fractions of commercial tea and tannic acid were tested for mutagenicity in Ames test. Tea fractions of tannic acid were non mutagenic in strains TA 100, TA 98, TA 1535 and TA 1538 of Salmonella typhimurium with or without metabolic activation (rat-S9 mix) at different doses tested. In strain TA 98 the above tea fractions and tannic acid inhibited the S9 mix mediated mutagenicity of tobacco in a dose dependent manner. The different tea fractions at 60 degrees C, did not increase the tumor incidence in Swiss mice by gavage feeding. They also failed to produce tumors when injected subcutaneously. Caffeine free tea extract decreased the tobacco induced liver tumors but had no effect on lung tumors. The same fraction was ineffective in hexachlorocyclohexane induced liver tumors in Swiss mice.

Hydroxychavicol: a new anti-nitrosating phenolic compound from betel leaf.

Hydroxychavicol and eugenol are the phenolic compounds isolated from betel leaf (piper betel). The modulation of nitrosation of methylurea by sodium nitrite at pH 3.6 and 30 degrees C was studied. The formation of mutagenic N-nitrosomethylurea was monitored by checking the mutagenicity of reaction mixture in Salmonella typhimurium strain TA100 and TA1535 without S9 mix. Hydroxychavicol and eugenol exhibit dose-dependent suppression of nitrosation in vitro without affecting the survival of the bacteria. Pre- or post-treatment of bacterial cells from S. typhimurium strains TA100 and TA1535 with phenolics did not modify the mutagenicity of nitrosomethylurea. The blocking of hydroxy group(s) in the benzene ring by acetylation abolishes the anti-nitrosating activity of the molecule(s). The nitrosation inhibition by hydroxychavicol is through scavenging of nitrite ions in the media, thus making them non-available for the nitrosation of methylurea.

Curcumins as inhibitors of nitrosation in vitro.

The effects of turmeric extract and its pure yellow pigments curcumin I, II and III were tested on the nitrosation of methylurea by sodium nitrite at pH 3.6 and 30 degrees C. The nitrosomethylurea formed was monitored by checking the mutagenicity in S. typhimurium strains TA1535 and TA100 without metabolic activation. Turmeric extract as well as curcumins exhibit dose-dependent decreases of nitrosation. Curcumin III was the most effective nitrosation inhibitor among the compounds tested. The simultaneous treatment of inhibitor with nitrosation precursors was essential and pre- or post-treatment of inhibitor had no effect on the mutagenicity of nitrosomethylurea. The binding of nitrite with the inhibitors was studied at pH 3.6 and 30 degrees C. Curcumin I shows a dose-dependent depletion of nitrite ions thus making nitrite non-available for nitrosation. Curcumin I and III when tested also showed a time-dependent depletion of nitrite ions at pH 3.6 and 30 degrees C. Curcumin III has a higher affinity for nitrite ions than curcumin I.

Catechin as an antimutagen: its mode of action.

In the present study, we report that the betel quid ingredient catechu, its extract and pure principle catechin were nonmutagenic in Salmonella typhimurium TA 100, TA 1535, TA 98, and TA 1538 assays with or without metabolic activation. They also exhibited dose-dependent decreases in mutagenicity of benzo(a)pyrene [B(a)P] and dimethylbenz(a)anthracene (DMBA) in strain TA 98 with metabolic activation. We further report that these compounds inhibited activities of cytochrome P-450 and had no effect on glutathione-S-transferase but increased the glutathione content in rat liver tissue. Simultaneous treatment of catechin prevented the mutagenic activity of B(a)P and DMBA metabolites in strain TA 98 in the absence of metabolic activation. Pre- and post-treatment of bacteria with catechin had no effect on the mutagenicity of B(a)P and DMBA metabolites. Catechin also inhibited the in vitro binding of 3H-B(a)P metabolites to calf thymus DNA. Catechu extract and catechin inhibited the nitrosation of methylurea by nitrite at pH 3.6 and 30 degrees C. The formation of nitrosomethylurea in the reaction mixture was monitored by measuring the histidine revertants of strain TA 1535 in the absence of metabolic activation. Pre- and post-treatment of catechu extract or catechin had no effect on the mutagenicity of nitrosomethylurea in TA 1535. The nitrosation inhibition by catechin was through scavenging of nitrite observed at pH 3.6. The above study indicates that catechu in betel quid may act as an antimutagen and may suppress the mutagenic potential of other betel quid mutagens.