Safety evaluation of 5-hydroxytryptophan and S-(2-aminoethyl)isothiouronium bromide hydrobromide on rodent lungs.

OBJECTIVES: During the past few decades, various compounds have been researched for their potential as radioprotectants, and many of them were found to be safe and effective in several preclinical models. However, many of these compounds were found to have serious adverse effects when evaluated in clinical settings, thereby making them unsuitable for human applications. 5-hydroxytryptophan (5-HTP) and S-(2-aminoethyl) isothiouronium bromide hydrobromide (AET) act in a synergistic fashion to promote radioprotection. The present study primarily emphasizes the safety of fixed dose of 5-HTP + AET in the lungs of C57BL/6 mice, a well-known model used in drug safety studies. MATERIALS AND METHODS: Post-administration of the combination of HTP+AET at specific time points, blood and bronchoalveolar lavage fluid (BALF) were collected for the analysis of inflammatory and oxidative stress markers of the lungs. Thereafter, the mice were sacrificed and the lungs were dissected out, weighed, and fixed in formalin for histopathological studies. RESULTS: The inflammatory biomarkers: tumor necrosis factor-alpha and interleukin-10 and oxidative stress biomarkers: 8-isoprostane and 8-hydroxy-2'-deoxyguanosine were found to have normal levels in blood and BALF in both control and treatment groups, which was further supported by normal histological findings. In addition, other endpoints such as food and water intake were found to be within normal limits. CONCLUSION: The present safety study reflects that the combination has no adverse effects on the lungs of the experimental mouse. Further, evaluation in higher mammals including nonhuman primates is essential prior to validation of the safety of the combination in humans.

Patient experiences and views on pharmaceutical care during adjuvant endocrine therapy for breast cancer: A qualitative study.

OBJECTIVE: The use of adjuvant endocrine therapy (AET) after primary treatment of hormone receptor-positive breast cancer reduces the risk of recurrence and mortality. However, non-adherence is still common. Limited consideration has been given to how users deal with AET and the role of pharmaceutical care. Therefore, this study aims to obtain insight into the needs and wishes of women using AET regarding pharmaceutical care and eHealth. METHODS: This is a qualitative explorative study comprising semi-structured interviews (n = 16) and a focus group (n = 5) among women who use or used AET after primary early-stage breast cancer (EBC) treatment using a thematic analysis approach. RESULTS: Three themes emerged from the interviews and focus group: (1) experiences with AET use, (2) experiences with provided information and (3) needs and wishes regarding pharmaceutical care. Most women were highly motivated to use AET and indicated to have received useful information on AET. However, many expressed a strong need for more elaborate tailored and timely provided information on AET. They acknowledged the accessibility of pharmacists but reported that currently, pharmacists are hardly involved in AET care. Several women considered eHealth useful to obtain counselling and reliable information. CONCLUSION: Women need more comprehensive information and follow-up in primary setting after initial cancer treatments. A more elaborate role for the pharmacy and eHealth/mHealth, especially with regard to counselling on side effects and side effect management, could potentially improve pharmaceutical care.

Strategies to self-manage side-effects of adjuvant endocrine therapy among breast cancer survivors: an umbrella review of empirical evidence and clinical guidelines.

PURPOSE: Side-effects of adjuvant endocrine therapy (AET) are common in breast cancer survivors, and can affect adherence to treatment. We synthesised the evidence for strategies to self-manage these side-effects. METHODS: We searched for systematic reviews and clinical guidelines on self-management strategies for AET side-effects (arthralgia, fatigue, hot flashes, gastrointestinal discomfort, nausea, vulvovaginal symptoms, and sleep disturbance). We searched oncology organisation's websites and eight databases (Inception-November 2020). Screening, data extraction and quality assessment were completed independently in duplicate. PROSPERO: 2019CRD4201914001. RESULTS: We identified 33 systematic reviews and 18 clinical guidelines. 21% of reviews were high quality, and the average quality score for guidelines was 44%. Evidence for most strategies was absent or weak. There was consensus from a low-quality review and multiple guidelines to recommend moisturisers, gels and lubricants for vulvovaginal symptoms. Evidence was weak for physical activity for self-managing most symptoms, although two high-quality reviews indicated yoga and aerobic exercise could reduce fatigue. Primary research was often biased by weak and underpowered study designs. Eleven reviews did not report information on adverse events. CONCLUSIONS: Most self-management strategies for breast cancer survivors experiencing side-effects from AET lack evidence. Primary research is needed using high-quality well-powered designs focusing on implementable strategies. IMPLICATIONS FOR CANCER SURVIVORS: Patients and clinicians should be aware that although the risk of harm is low for these self-management strategies, the likelihood of benefit is often unclear. Women should consider moisturisers, gels or lubricants for self-managing vulvovaginal symptoms, and yoga or aerobic exercise for alleviating fatigue.

Is there a role of inducible nitric oxide synthase activation in the delayed antiarrhythmic effect of sodium nitrite?

This study aimed to examine whether inducible nitric oxide synthase (iNOS) plays a role in the delayed antiarrhythmic effect of sodium nitrite. Twenty-one dogs were infused intravenously with sodium nitrite (0.2 µmol·kg-1·min-1) for 20 min, either in the absence (n = 12) or in the presence of the iNOS inhibitor S-(2-aminoethyl)-isothiourea (AEST) (total dose 2.0 mg·kg-1 i.v., n = 9). Control dogs (n = 12) were given saline. Twenty-four hours later, all of the dogs were subjected to a 25 min period occlusion of the left anterior descending coronary artery followed by rapid reperfusion. Dogs treated with AEST and nitrite received again AEST prior to the occlusion. Compared with the controls, sodium nitrite markedly reduced the number of ectopic beats, the number and incidence of ventricular tachycardia, and the incidence of ventricular fibrillation during occlusion and increased survival (0% versus 50%) from the combined ischaemia and reperfusion insult. Although AEST completely inhibited iNOS activity, the nitrite-induced increase in NO bioavailability during occlusion was not substantially modified. Furthermore, AEST attenuated but did not completely abolish the antiarrhythmic effect of nitrite. The marked delayed antiarrhythmic effect of sodium nitrite is not entirely due to the activation of iNOS; other mechanisms may certainly play a role.

Isolation of T Cells Using Rosetting Procedures.

This unit describes a procedure for separating T cells from other mononuclear cells by exploiting the unique ability of cells to bind to and form rosettes with sheep red blood cells (SRBC). This isolation method also allows recovery of the nonrosetting cell population (B lymphocytes, monocytes, and macrophages). Neuraminidase- and 2-aminoethylisothiouronium bromide (AET)-treated SRBC are used for rosetting because of enhanced binding to T cells. It should be noted that use of the rosetting technique to obtain purified T cells or purified non-T cells by negative selection has largely been superceded by other techniques such as panning and immunomagnetic beads.

Does Measurement of Esophagogastric Junction Distensibility by EndoFLIP Predict Therapy-responsiveness to Endoluminal Fundoplication in Patients With Gastroesophageal Reflux Disease?

BACKGROUND/AIMS: In patients with gastroesophageal reflux disease (GERD), an increased esophagogastric junction (EGJ) distensibility has been described. Assessment of EGJ distensibility with the endoscopic functional luminal imaging probe (EndoFLIP) technique might identify patients responsive to transoral incisionless fundoplication (TIF), whereas postoperative measurement of EGJ distensibility might provide insight into the antireflux mechanism of TIF. Therefore, we investigated the value of the EndoFLIP technique in GERD patients treated by TIF. METHODS: Forty-two GERD patients underwent EGJ distensibility measurement before TIF using the EndoFLIP technique. In a subgroup of 25 patients, EndoFLIP measurement was repeated both postoperative and at 6 months follow-up. Treatment outcome was assessed according to esophageal acid exposure time (AET; objective outcome) and symptom scores (clinical outcome) 6 months after TIF. RESULTS: Multiple logistic regression analysis showed that preoperative EGJ distensibility (OR, 0.16; 95% CI, 0.03-0.78; P = 0.023) and preoperative AET (OR, 0.62; 95% CI, 0.42-0.90; P = 0.013) were independent predictors for objective treatment outcome but not for clinical outcome after TIF. The best cut-off value for objective outcome was 2.3 mm2/mmHg for preoperative EGJ distensibility and 11% for preoperative AET. EGJ distensibility decreased direct postoperative from 2.0 (1.2-3.3) to 1.4 (1.0-2.2) mm2/mmHg (P = 0.014), but increased to 2.2 (1.5-3.0) at 6 months follow-up (P = 0.925, compared to preoperative). CONCLUSIONS: Preoperative EGJ distensibility and preoperative AET were independent predictors for objective treatment outcome but not for clinical outcome after TIF. According to our data, the EndoFLIP technique has no added value either in the preoperative diagnostic work-up or in the post-procedure evaluation of endoluminal antireflux therapy.

[Radioprotective properties of isothiourea derivatives with NO-inhibitory mechanism of action].

The study of the radioprotective activity of S-[2-alkyl (aryl) sulfonyl]-S-ethyl derivatives of (vinyl)-isothiourea in (he model of the survival of mice exposed to gamma-radiation at a dose of 10 Gy has shown that the incorporation of additional sulfur-containing groups does not increase the radioprotective properties of compounds. In contrast to aminoalkil thiols, the effectiveness of the radiation protection action of the isothiourea (ITU) derivatives studied clearly correlates with the NO-inhibitory activity. This fact allowed us to assume that the radioprotective effect of S-substituted ITU caused inhibition of the endogenous synthesis of NO, which promotes the development of circulatory hypoxia, and that a further search for the radioprotective agents in this class of chemicals should be considered as the search for effective inhibitors of NO-synthase (NOS). The theoretical analysis of the conformity of molecular structures to the composition and topology of the active center of NOS-inhibitors allowed us to prognosticate a number of new ITU derivatives with the potential NOS-inhibiting ability. As a result of further theoretical and experimental studies, four S,N-disubstituted ITU derivatives - active non-selective NOS-inhibitors, were first identified and synthesized. These compounds exhibited a pronounced and prolonged vasopressive effects at doses of 0.01-0.05 LD50/15 in the models of severe hemorrhagic and endotoxic shock, and provided 65-100% 30-day survival at doses of 0.2-0.3 LD50/15 in the mice irradiated by gamma-rays at a dose of 10 Gy (LD98/30).The findings suggest the pronounced radioprotective effect of NOS-inhibitors among the ITU-derivatives.

Efecto de distintos antimicrobianos sobre el crecimiento de Listeria monocytogenes / Effect of different antimicrobial agents on the growth of Listeria monocytogenes

En este estudio se ha evaluado la eficacia de dos ácidos orgánicos contemplados en la lista positiva de aditivos alimentarios, el lactato sódico (E-325) y el diacetato sódico (E-262), sobre el crecimiento de Listeria monocytogenes. Estos aditivos se adicionaron en diferentes concentraciones a un medio de cultivo líquido, determinando el incremento de densidad óptica del medio a 600 nm durante 24 horas a 37 ºC, con respecto al medio sin inocular que se tomó como blanco, realizando la medida cada hora. El incremento de absorbancia se midió con respecto al tiempo, evaluando el crecimiento de la bacteria a través de la interpretación de la tasa máxima de incremento de absorbancia (micro) y el tiempo mínimo requerido para detectar un incremento en la densidad óptica del medio (epsilon). Este último parámetro se puede equiparar al tiempo de latencia o tiempo de adaptación al medio. Así, para el lactato sódico, se observó que ejerce un efecto negativo dosis dependiente sobre el crecimiento de L. monocytogenes, prolongando el tiempo que necesitó la bacteria para adaptarse al medio de cultivo (epsilon), sin afectar a la tasa de crecimiento (micro) una vez que esta comenzó a crecer. El diacetato sódico mostró ser más efectivo que el lactato sódico frente al crecimiento de la bacteria, incrementando el tiempo de adaptación al medio, así como disminuyendo la tasa de crecimiento. Además, el diacetato sódico consiguió inhibir de forma completa el crecimiento de la bacteria a concentraciones iguales o superiores a 0.2%(AU)

The effectiveness of two organic acids included in the positive list for additives, sodium lactate (E-325) and sodium diacetate (E-262), was evaluated against Listeria monocytogenes growth. Different concentrations of these additives were added to the liquid culture medium. The optical density increments at 600 nm was measured for a 24 hours period under 37 0C, using non-inoculated medium as blank. The measurements were taken every hour in sterile 96 wells plates each. After this analysis, a graphical representation of absorbance increment against time was done, extrapolating the maximum absorbance increment rate (micro) and the minimum time required to detect an absorbance increment (epsilon) from the graphic. These two parameters made possible to evaluate the bacterial growth. After the analysis of epsilon and micro for lactate concentrations, a negative effect in bacterial growth was observed, extending epsilon value. Nevertheless, once the bacterial growth started, any effect on micro value was detected. A higher inhibitory effect was observed after the analysis of these parameters for diacetate concentrations, an extension on epsilon value as well as a micro value descent was found. In this way, a total inhibition of growth occurred when diacetate concentration was 0,2% or higher(AU)

Anti-T haemolysins: the effects of sialic acid removal and 2-aminoethylisothiouronium bromide treatment of erythrocytes on immune lysis.

BACKGROUND AND OBJECTIVES: Intravascular haemolytic reactions are reported in red-cell T-activated patients after blood transfusion. The relationship between T antigen antibodies present in normal plasma and these reactions remains unclear. In this study, we assessed the haemolytic activity of T antibodies in vitro in comparison with anti-A/B antibodies. MATERIALS AND METHODS: We established a haemolysis assay based on treating target red-blood-cells (RBCs) with 2-aminoethylisothiouronium bromide (AET). Two hundred and seven blood donor sera were analysed for anti-T, anti-A/B haemolysins and anti-T agglutinins. RESULTS: Anti-T haemolysins were found in 4 (1·9%) blood donor sera using a standard haemolysis method and in 174 (84%) samples using AET-treated RBCs. Haemolysis correlated with agglutination titres (P<10(-7) ). With both methods, anti-T haemolysins were much weaker than anti-A and anti-B haemolysins. Gradual desialylation of RBCs showed a correlation between sialic acid level as indicated by agglutination with Sambucus nigra lectin and anti-T mediated haemolysis that was significantly increased (fold 2·4) independently of T antigen expression. CONCLUSION: These data indicate that, in vitro, anti-T-mediated haemolysis depends primarily on the degree of desialylation of target RBCs. They suggest that the haemolytic activity of T antibodies-containing human sera is usually weak and may only become significant in the very rare setting of a profound desialylation of RBCs.

Kinetic evaluation of aminoethylisothiourea on mushroom tyrosinase activity.

This study demonstrates that aminoethylisothiourea (AET), a potent inhibitor of inducible nitric oxide synthase, is an irreversible competitive inhibitor of mushroom tyrosinase by chelation to the active site of tyrosinase when L-3,4-dihydroxyphenylalanine was assayed spectrophotometrically. The spectrophotometric recordings of the inhibition of tyrosinase by AET were characterized by the presence of a lag period prior to the attainment of an inhibited steady-state rate. The lag period corresponded to the time in which AET was reacting with the enzymatically generated o-quinone. Increasing AET concentrations provoked longer lag periods as well as a concomitant decrease in the tyrosinase activity. Both lag period and steady-state rate were dependent on AET, substrate, and tyrosinase concentrations. The inhibition of diphenolase activity of tyrosinase by AET showed positive kinetic cooperativity which arose from the protection of both substrate and o-quinone against inhibition by AET. The UV-visible spectrum of a mixture of tyrosinase and AET exhibited a characteristic shoulder peak ascribed to the chelation of AET to the active site of tyrosinase. Moreover, the presence of copper ions only partially prevented but not reverted mushroom tyrosinase inhibition when CuSO(4) was added to the assay medium on tyrosinase activity.

Radioprotective effects of quercetin and ethanolic extract of propolis in gamma-irradiated mice.

The aim of this study was to assess radioprotective effects of quercetin and the ethanolic extract of propolis (EEP) in CBA mice exposed to a single radiation dose 4 Gy (60Co). The mice were treated with 100 mg kg(-1) quercetin or EEP a day for three consecutive days either before (pre-treatment) or after gamma-irradiation (therapy). Leukocyte count was determined in blood drawn from the tail vein, and DNA damage in leukocytes was assessed using the alkaline comet assay. Genotoxic effects of the test compounds were also evaluated in non-irradiated mice. The levels of radioprotection provided by both test compounds were compared with those established in mice that were given chemical radioprotector S-(2-aminoethy1)isothiouronium bromide hydrobromide (AET). Mice that received pre-treatment were less sensitive to irradiation. Mice given the post-irradiation therapy showed a slight but not significant increase in total leukocyte count over irradiated negative control. Quercetin showed better protective properties than EEP in both pre-treatment and therapy, and activated a higher number of leukocytes in non-irradiated mice. The alkaline comet assay suggests that both natural compounds, especially when given as pre-treatment, protect against primary leukocyte DNA damage in mice. At tested concentrations, EEP and quercetin were not genotoxic to non-irradiated mice. AET, however, caused a slight but not significant increase in DNA damage. Although the results of this study show the radioprotective potential of the test compounds, further investigation is needed to clarify the underlying protection mechanisms.

The role of nitric oxide in radiation damage.

This study investigated the role of nitric oxide in radiation-induced damage by examining changes in mouse serum nitrate concentrations after irradiation. In addition, the contribution of S-2-aminoethylisothiourea 2HBr (AET) to the mechanisms of radiation damage protection was also clarified. The serum nitrate concentration increased as soon as 1.5 h after irradiation, and after 2.5 to 3.0 h the concentrations were significantly higher compared with normal levels. Normal levels were re-established after 12 h. Post-irradiation serum nitrate concentrations increased dose-dependently with irradiation dose (19.6-31.5 Gy). AET suppressed increases in the serum nitrate concentration following irradiation while 2-mercaptoethylamine HCl (MEA) did not. AET has an inhibitory effect on inducible nitric oxide synthase (iNOS); therefore, the increase in nitric oxide after irradiation may be produced by iNOS. Combined administration of irradiation and lipopolysaccharide (LPS) induced a significant increase in serum nitrate concentration, and a significant decrease in survival rate, compared with irradiation alone. The administration of AET or aminoguanidine increased survival rate following irradiation. In contrast to findings after LPS administration, IL-1beta and IFN-gamma were not determined in serum following irradiation. Existing iNOS is activated by irradiation, and nitric oxide production appears to increase without iNOS induction. Thus, the irradiation-induced increase in nitric oxide may be related to lethal injury.

Intracellular and extracellular NO differentially modulates the stress response and apoptosis in macrophages exposed to the influence of biological or physical factors.

We studied the role of extracellular and intracellular NO in the regulation of the stress response and apoptosis in macrophages of proinflammatory and antiinflammatory phenotypes under the influence of S. aureus and heat shock. Blockade of extracellular nitric oxide synthesis in cells with antiinflammatory phenotype inhibited the stress response induced by S. aureus and heat shock. The decrease in extracellular nitric oxide concentration around antiinflammatory macrophages potentiated the stress response induced by S. aureus, but had no effect on the stress response induced by heat shock. Hence, intracellular NO mediates the stress response induced by S. aureus and heat shock, while extracellular NO inhibits the stress response induced by S. aureus, but has no effect on the stress response induced by heat shock. In cells with antiinflammatory phenotype, intracellular NO plays an antiapoptotic role. S. aureus and heat shock did not cause apoptosis in macrophages with proinflammatory phenotype, while intracellular NO did not play a role in antiapoptotic activity of the proinflammatory phenotype. Extracellular NO synthesized by macrophages protects these cells from apoptosis induced by S. aureus and heat shock.

Polyamines induce rapid biosynthesis of nitric oxide (NO) in Arabidopsis thaliana seedlings.

In this study, we examined the regulation by putrescine, spermidine and spermine of nitric oxide (NO) biosynthesis in Arabidopsis thaliana seedlings. Using a fluorimetric method employing the cell-impermeable NO-binding dye diaminorhodamine-4M (DAR-4M), we observed that the polyamines (PAs) spermidine and spermine greatly increased NO release in the seedlings, whereas arginine and putrescine had little or no effect. Spermine, the most active PA, stimulated NO release with no apparent lag phase. The response was quenched by addition of 2-aminoethyl-2-thiopseudourea (AET), an inhibitor of the animal nitric oxide synthase (NOS) and plant NO biosynthesis, and by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-1-oxy-3-oxide (PTIO), an NO scavenger. By fluorescence microscopy, using the cell-permeable NO-binding dye diaminorhodamine-4M acetoxymethyl ester (DAR-4M AM), we observed that PAs induced NO biosynthesis in specific tissues in Arabidopsis seedlings. Spermine and spermidine increased NO biosynthesis in the elongation zone of the Arabidopsis root tip and in primary leaves, especially in the veins and trichomes, while in cotyledons little or no effect of PAs beyond the endogenous levels of NO-induced fluorescence was observed. We conclude that PAs induce NO biosynthesis in plants.

Nitric oxide involvement in the delayed antiarrhythmic effect of treadmill exercise in dogs.

We have shown previously that a single period of treadmill exercise in dogs protects the heart against the severe ventricular arrhythmias that arise when a major (anterior descending) branch of the left coronary artery is occluded following anaesthesia 24 h later. This protection is aminoguanidine sensitive, suggesting a role for nitric oxide (NO) in this exercise-induced delayed antiarrhythmic effect. The present study has further examined the possible role of NO as a mediator and/or as a trigger using the selective induced (iNOS) inhibitor S-(2-aminoethyl)-methyl-isothiourea (AEST) and the specific but not selective nitric oxide synthase inhibitor N(omega)-nitro-L-arginine-methyl-ester (L-NAME). Exercise markedly reduced the severity of ischaemia and reperfusion-induced ventricular arrhythmias 24 h later. Thus, only one of the dogs (8%) so exercised fibrillated on occlusion (contrast 46% in the control, non-exercised dogs; P<0.05) and the marked changes in the inhomogeneity of electrical activation that occur in the ischaemic region following occlusion were much reduced (P<0.05 compared to controls). This delayed exercise-induced cardioprotection was significantly attenuated by the nitric oxide synthase (NOS) inhibitors L-NAME, given prior to the exercise protocol and by AEST given prior to the coronary artery occlusion. For example, survival from the ischaemia-reperfusion insult was 54% in the exercise dogs, 0% in the controls and 14% in those dogs given a NOS inhibitor. We conclude that nitric oxide (NO) is both the trigger and the mediator of this delayed protection against ischaemia and reperfusion-induced arrhythmias.

Association between the expression of inducible nitric oxide synthase by chondrocytes and its nitric oxide-generating activity in adjuvant arthritis in rats.

Inducible nitric oxide synthase (iNOS) is one of the clinical targets in rheumatoid arthritis. Synoviocytes, macrophages, and chondrocytes in the joints of patients with rheumatoid arthritis appear to express iNOS, but the contribution of iNOS molecules to rheumatoid arthritis is not yet clear. This study used adjuvant-induced arthritis in rats as a model to examine the association between the iNOS expression and its activity in rheumatoid arthritis. In adjuvant-injected rats, arthritic changes in the paw were first observed between days 10 and 12. NO-generation activity was precisely determined by combining an electron spin resonance/nitric oxide (NO)-trapping method with the method of standard addition using an NO generator, and we found that the activity in the joint samples was extremely high on day 10. The administration of S-(2-aminoethyl)isothiourea, a selective iNOS inhibitor, from day 0 to day 10, effectively reduced the paw swelling. Immunohistological studies showed that chondrocytes expressed iNOS on days 7-14 and that nitrotyrosine residues, a footprint of NO generation, were produced on day 10. This indicates that NO generation by iNOS induced in chondrocytes is a key event in the induction of adjuvant arthritis.

Enhancement of antiradiation potential of some aminothiols by beta-carotene.

In the present study, protection of mice, BALB/c inbred as measured by survival at 30 days against whole-body gamma exposure at two dose levels, namely, 7.60 and 10.12 Gy by prior irradiation treatment with combination of beta-carotene, N-(2-mercapto-propionyl)-glycine (MPG) and S-(2-aminoethyl) isothiouroniumbromide hydrobromide (AET), is reported. It was found that administration of beta-carotene (1 mg per 20 g body mass) and 24 h before whole-body irradiation (7.60 Gy) had significantly improved the post-irradiation survival. It was also found that administration of a combination of AET (260 mg per kg body mass) and MPG (60 mg per kg body mass) 20 min before exposure to 7.60 Gy gamma irradiation to mice which have been treated with beta-carotene (1 mg per 20 g body mass) 24 h before exposure had resulted in 80% survival in comparison to 10% survival recorded for control animals. On the other hand, when the animals were exposed to a higher dose (10.12 Gy) under similar experimental conditions as above, a significant improvement in survival was observed during the first 10 days following the exposure but only a slight effect afterward. On the other hand, the response of male and female mice 10 days after exposure to the above radiation dose indicated that the females were more radioresistant than the males.

[Study of the antiradical and radioprotective properties of S-containing compounds using the complex of in vitro test-systems]. / Izluchenie antiradikal'nykh i protivoluchevykh svoistv S-soderzhashchikh soedinenii s ispol'zovaniem kompleksa test-sistem in vitro.

Capability of S-radioprotectors (AET, 2-AT, 2-ADT) to react with OH-radicals and to protect various molecular biotest systems against radiation damage was compared with that of 5-methoxytryptamine, some amino acids and t-butanol. A method of competing acceptors was used to determine rate constants in reactions of the radioprotectors with OH-radicals. A complex of biotest systems (protein, DNA, protein-lipid complex) was applied to estimate the radioprotective activity in vitro. It was found that the studied S-compounds are capable of modifying the protective effect as compared to the expectation from the competitive kinetics approach. Both enhancing and lessening of the effect was observed depending on the test system used. The obtained results can be explained by the impact of secondary radicals on the bio-target and/or by the interaction of the S-compounds with the bio-target that altered its radiosensitivity.

Differential activity of NO synthase inhibitors as chemopreventive agents in a primary rat tracheal epithelial cell transformation system.

A model to study the effectiveness of potential chemopreventive agents that inhibit neoplastic process by different mechanisms has been used to test the efficacy of seven nitric oxide synthase (NOS) inhibitors. Five selective inducible NOS (iNOS) inhibitors: S-methyl isothiourea (S-MITU), S-2-aminoethyl isothiourea (S-2-AEITU), S-ethyl isothiourea (S-EITU), aminoguanidine (AG), 2-amino-4-methyl pyridine (2-AMP), and two non selective general NOS inhibitors: l-N(6)-(1-iminoethyl) lysine (IEL) and N(omega)-nitro-l-arginine (NNLA), were tested for efficacy against a carcinogen, benzo[a]pyrene (B[a]P)-induced primary rat tracheal epithelial (RTE) cell transformation assay. RTE cells were treated with B[a]P alone or with five nontoxic concentrations of an NOS inhibitor and the resulting foci at the end of 30 days were scored for inhibition of transformation. The results indicate that all three isothiourea compounds inhibited B[a]P-induced RTE foci in a dose-dependent manner. S-AEITU was the most effective inhibitor with an IC(50) (the molar concentration that inhibits transformation by 50%) of 9.1 microM and 100% inhibition at the highest dose tested (30 microM). However, both S-EITU and S-MITU showed a maximum percent inhibition of 81% and 100% at 1 mM with an IC(50) of 84 and 110 microM, respectively. 2-AMP did not show any dose-dependent response, but was highly effective (57% inhibition) at an intermediate dose of 30 microM and an IC(50) of 25 microM. Similar to thiourea compounds, AG exhibited good dose-dependent inhibition with a maximum inhibition of 86% at 1 mM. NNLA and IEL were negative in this assay. Based on the IC(50) values, NOS inhibitors were rated for efficacy from high to low as follows: S-2-AEITU<2-AMP

Osteopontin is induced by nitric oxide in RAW 264.7 cells.

Nitric oxide (NO) produced by macrophages is thought to contribute to various pathological conditions. Osteopontin (OPN) is a phosphorylated glycoprotein produced principally by macrophages. OPN inhibits inducible nitric oxide synthase (iNOS), which generates large amounts of NO production. However, the relationship between NO and endogenous OPN in activated macrophages has not yet been elucidated. We therefore examined expression of endogenous iNOS and OPN in a murine macrophage cell line, RAW 264.7 cells, by treating the cells with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Treatment of cells with LPS and IFN-gamma resulted in an increase of iNOS mRNA to maximum at 12 h after stimulation. In contrast, OPN mRNA was induced more slowly than iNOS mRNA. Induction of both iNOS and OPN mRNA in RAW 264.7 cells was markedly suppressed by addition of the specific iNOS inhibitor S-2-aminoethyl isothiourea dihydrobromide. The NOS inhibitor NG-methyl-L-arginine also suppressed induction of OPN mRNA but hardly affected iNOS mRNA expression. The NO-releasing agent spermine-NONOate but not peroxynitrite enhanced induction of OPN mRNA. These results suggest that NO directly up-regulates the endogenous OPN in macrophages stimulated with LPS and IFN-gamma. This up-regulation of endogenous OPN may represent a negative feedback system acting to reduce iNOS expression.