Aquatic ecotoxicity of a pheromonal antagonist in Daphnia magna and Desmodesmus subspicatus

Evaluation of the ecotoxicological potential of (Z)-11-hexadecenyl trifluoromethyl ketone (Z11-16:TFMK), a new biorational agent with high prospective features to control the Mediterranean corn borer Sesamia nonagrioides in infested maize fields, in comparison to the parent pheromone compound (Z)-11-hexadecenyl acetate (Z11-16:Ac) is described. Acute and sublethal toxicity tests of both compounds against the cladoceran Daphnia magna and the chlorophyte Desmodesmus subspicatus were conducted, the endpoints being immobilisation and feeding inhibition for Daphnia and growth rate inhibition for Desmodesmus. In addition, effects on B esterases including cholinesterase and carboxylesterase activities in Daphnia were also assessed to evaluate the mode of action of both chemicals. Toxicities of both compounds were moderate with EC(50) values ranging from 3.11 to 103.74mgl(-1) in algae growth, from 0.07 to 1.20mgl(-1) in Daphnia survival, and from 0.10 to 0.53mgl(-1) in Daphnia feeding rate. In all cases Z11-16:TFMK was more toxic than the naturally occurring pheromone component. Serine esterase assays showed a strong inhibition of the carboxylesterase activities in Daphnia at concentrations with apparently no effects on survival or feeding, suggesting that inhibition of other key esterases may be the possible mechanism of toxicity of this compound. The results obtained have been related with some physico-chemical properties of the compounds, such as water solubility and octanol-water partition coefficient, suggesting that Z11-16:TFMK may affect aquatic organisms at lower concentrations than expected from non-polar narcosis.

Phenolic components and antioxidant activity of Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos

Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos, used as raw material for topical and oral photoprotective formulations, was fractioned by HPLC and the main components with antioxidant capability were identified by means of UV spectra, electrochemical detection, and MSn. Phenolic compounds were identified as 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, caffeic acid, 4-hydroxycinnamic acid, 4-hydroxycinnamoyl-quinic acid, ferulic acid, and five chlorogenic acid isomers. Total ferric antioxidant capacity (FRAP) of HPLC eluted fractions was measured. The results suggest that the herein identified compounds support, at least partially, the antioxidant and radical scavenging capacities of Fernblock.

Effects of hypoxia reoxygenation in brain slices from rats with type 1-like diabetes mellitus

BACKGROUND

The aim of this study was to determine whether the brain tissue of type 1 diabetic animals is more susceptible to damage by hypoxia reoxygenation than healthy animals.

METHODS

This study used rats with diabetes of 1, 2 and 3 months (N = 15 rats/group). Brain slices were subjected to hypoxia and reoxygenation for 180 min in vitro. We measured oxidative stress (lipid peroxidation, glutathione concentration and enzyme activities related to glutathione), concentration of prostaglandin E(2) (PGE(2)) and nitric oxide (NO) pathway (nitrite + nitrate, activities of constitutive (cNOS) and inducible (iNOS) nitric oxide synthase). As a parameter of cell death we measured the efflux of lactate dehydrogenase (LDH).

RESULTS

After reoxygenation LDH activity increased in comparison to nondiabetic animals by 40, 40.6 and 68.9% in animals with diabetes of 1, 2 and 3 months duration, respectively. These changes were accompanied by greater increases in lipid peroxides (25.4, 93.7 and 92.8%). PGE(2) accumulated in significantly larger amounts in diabetic animals (62.5, 85.5 and 114%), and nitrite + nitrate accumulation was significantly greater in rats with diabetes of 2 (40.2%) and 3 months duration (24.0%). iNOS activity increased significantly in all the groups of diabetic animals, with the largest increases in rats with diabetes of 2 (18.6%) and 3 months duration (21.1%).

CONCLUSIONS

The biochemical pathways involved in oxidative stress and neuronal death are more sensitive to hypoxia reoxygenation in type 1-like diabetic, as compared to normal, rats.

Clinical response at 4 months to neoadjuvant letrozole predicts distant disease free survival in postmenopausal women with stage II-III ER/PgR-positive breast cancer

10531

Background: Letrozole (L) is more active than tamoxifen in early stage ER[+] breast cancer both as adjuvant (BIG-98 trial) or neoadjuvant (LET-024) therapy. However, complete pathological remissions to neoadjuvant endocrine therapy are anecdotal (<5%), there are no new prognostic indicators with clinical implications. Methods: We have review our series of postmenopausal patients with stage II-III breast cancer ER/PgR[+] breast cancer treated in our institution with L as neoadjuvant therapy. All patients had completed 4 months of therapy (in the absence of PD), and had measurable clinical (or radiological) disease. An independent statistical analysis was conducted for disease free (DFS) and distant disease free survival (DDFS). Results: From IV/99 to XII/04, 107 patients fulfill the criteria. Median age 76 years (range 64 to 92); median tumour size 35 mm (range 25 to 100); cT2 75 (70%), cT3/4 32 (30%); cN[-] 83 (78%). The ORR (PR + CR) at 4 months was 63% (7 CR and 60 PR), 4 patients had PD as best response (4%) and 36 a SD (34%). Surgery was done in 63 patients (59%), including all non-responders. Only 2 patients received adjuvant CT. With a median follow-up of 32 month (range 8 to 66), 12 patients had relapsed (9 distant). The 3 years DFS and DDFS were 84% and 90% respectively. In univaried analysis: cN (p < 0.02), cT3/4 (p < 0.02), and clinical response at 4 months (CR) (p = 0.003) were related to DFS; and HER2 (p < 0.05), cN (p < 0.003), and CR (p = 0.007) with DDFS. Other factors like cT, HR-levels, or surgery were not significant. Multivariate analysis showed that only OR and cN remained independently predictive both for DFS and DDFS. Conclusions: Clinical response to neoadjuvant letrozole therapy is an independent predictor of distant disease free survival and could be of value to recommend or deny more aggressive therapies in addition to endocrine therapy.

[Table: see text]

No significant financial relationships to disclose.

Effects of aspirin plus alpha-tocopherol on brain slices damage after hypoxia-reoxygenation in rats with type 1-like diabetes mellitus

Diabetes mellitus is a risk factor for cerebrovascular ischemic disease. Aspirin (acetylsalicylic acid) is the most widely used drug for the secondary prevention of thrombotic phenomena. It has been also recently demonstrated that alpha-tocopherol influenced in vitro the antiplatelet effect of aspirin. The aim of the present study is to evaluate the effects aspirin plus alpha-tocopherol on cerebral oxidative stress, prostaglandin production and the nitric oxide pathway in a model of hypoxia-reoxygenation in rat brain slices. Our results show an imbalance in brain oxidative status (reflected mainly as the increase in lipid peroxides) as a result of diabetes itself rather than a failure of the glutathione-based antioxidant system. Moreover, our results also show a higher concentration of prostaglandins in the brain of diabetic animals and a higher nitric oxide concentration, mainly through a high iNOS activity. After 180 min of post-hypoxia reoxygenation, LDH activity was 40.6% higher in animals with diabetes, in comparison to non-diabetic animals. The increase of the LDH efflux observed in non-treated rats was reduced by 31.2% with aspirin, by 34.7% with alpha-tocopherol and by 69.8% with the association aspirin-alpha-tocopherol. The accumulation of prostaglandin E2 observed in diabetic non-treated rats was reduced statistically after the treatment with aspirin (34.2% inhibition), alpha-tocopherol (19.3% inhibition) or the association aspirin-alpha-tocopherol (54.4% inhibition). Nitric oxide production after 180 min reoxygenation was significantly reduced in aspirin (36.4%), alpha-tocopherol (22.7%) and aspirin-alpha-tocopherol (77.8%) treated rats with respect to diabetic non-treated animals; this was related mainly with a reduction in iNOS activity. The association between aspirin and alpha tocopherol could protects against brain ischemic-reperfusion damage with a better profile than aspirin alone.

Antioxidant and antiplatelet effects of the alpha-tocopherol-aspirin combination in type 1-like diabetic rats

We analyze the effect of the combination of acetylsalicylic acid (2 mg/kg/day p.o.) and alpha-tocopherol (25 mg/kg/day p.o.) in a type-1-like experimental model of diabetes mellitus on platelet factors, endothelial antithrombotic factors and tissue oxidative stress. In diabetic rats, the combination of drugs had a greater inhibitory effect on platelet aggregation than in untreated control animals with diabetes (88.87%). The combination of drugs had little effect on the inhibition of thromboxane production (-90.81%) in comparison to acetylsalicylic acid alone (-84.66%), potentiated prostacyclin production (+162%) in comparison to alpha-tocopherol alone (+30.55%), and potentiated nitric oxide production (+241%) in comparison to either drug alone (acetylsalicylic acid +125%, alpha-tocopherol +142%). The combination of the two drugs improved the thromboxane/prostacyclin balance (0.145+/-0.009) in comparison to untreated diabetic animals (4.221+/-0.264) and in untreated healthy animals (0.651+/-0.045). It did not potentiate the antioxidant effect of either drug alone, but did increase tissue concentrations of reduced glutathione, especially in vascular tissue (+90.09% in comparison to untreated animals). In conclusion, in the experimental model of diabetes tested here, the combination of acetylsalicylic acid and alpha-tocopherol led to beneficial changes that can help protect tissues from thrombotic and ischemic phenomena.

Phenotypic switching in Cryptococcus neoformans

Phenotypic switching has been described in serotype A and D strains of Cryptococcus neoformans. It occurs in vivo during chronic infection and is associated with differential gene expression and changes in virulence. The switch involves changes in the polysaccharide capsule and cell wall that affect the yeast's ability to resist phagocytosis. In addition, the phenotypic switch variants elicit qualitatively different inflammatory responses in the host. In animal models of chronic cryptococosis, the immune response of the host ultimately determines which of the switch variants are selected and maintained. The importance of phenotypic switching is further underscored by several findings that are relevant in the setting of human disease. These include the ability of the mucoid colony variant of RC-2 (RC-2 MC) but not the smooth variant (RC-2 SM) to promote increased intracerebral pressure in a rat model of cryptococcal meningitis. Furthermore, chemotherapeutic and immunological antifungal interventions can promote the selection of the RC-2 MC variant during chronic murine infection.

A new, mild, and efficient synthesis of 2,2-difluoro-3-hydroxyacids through a selective haloform reaction

[reaction: see text] Long-chain 2,2-difluoro-3-hydroxyacids have been synthesized in a new, straightforward manner by treatment of 4-hydroxy-1,1,1,3,3-pentafluoroalkyl ketones, easily obtained by reaction of pentafluoroenolate 2 with aldehydes and ketones, with base under mild conditions. The reaction sequence is marked by the selective cleavage of the CO-CF3 bond, as well as the absence of products arising from the alternative CO-CF2R bond cleavage. The process represents a convenient approach for the synthesis of 2,2-difluoro-3-hydroxyacids, as it is short, provides good to excellent yields under mild conditions, and uses hexafluoro-2-propanol, a very cheap reagent, as the fluorine source.

Inability of laser and rotary instrumentation to eliminate root canal infection

BACKGROUND

The authors evaluated the antibacterial effectiveness of laser instrumentation and rotary instrumentation of anterior, single-rooted teeth infected with Enterococcus faecalis.

METHODS

The authors divided 35 infected samples into five groups: Group A: inoculation, laser, 17 percent ethylene-diamine-tetra-acetate (EDTA), 2.5 percent sodium hypochlorite (NaOCl) (n=10); Group B: inoculation, laser, 17 percent EDTA, sterile saline (n = 10); Group C: inoculation, rotary, 17 percent EDTA, 2.5 percent NaOCl (n=10); Group D: inoculation, no instrumentation (positive control) (n=5); Group E: no inoculation, no instrumentation (negative control) (n=5). They sampled and incubated dentin shavings from each canal for bacterial growth.

RESULTS

In Group A, eight tubes were positive for bacterial growth. In Group B, 10 tubes were positive for bacterial growth. In Group C, six tube were positive for bacterial growth. In Group D, all of the tubes were positive for bacterial growth. In Group E, no tubes showed bacterial growth. The Fisher exact test showed no significant differences among groups A, E and C.

CONCLUSION

Neither the laser nor the rotary instrumentation was able to eliminate endodontic infection.

CLINICAL IMPLICATIONS

Although lasers have been presented as high-tech tools for disinfecting root canals, the laser was ineffective in this study.

Tumorangiogenese und Immunsuppression

BACKGROUND

Angiogenesis and tumor-associated immunosuppression are two of the hallmarks of carcinogenesis. In previous studies we demonstrated in vitro that HNSCC tumor cells attract monocytes via monocyte chemotactic protein-1 (MCP-1) and activate them via transforming growth factor-beta 1(TGF-beta1) to secrete interleukin (IL)-1alpha, which in turn stimulates tumor cells to secrete increased levels of the angiogenic and immunosuppressive vascular endothelial growth factor (VEGF). These findings suggest that interaction between the immune system and VEGF-mediated angiogenesis is important for progression of HNSCC. Recent studies in vitro show that retinoic acid (RA) downregulates the release of MCP-1 and TGF-beta1 by tumor cells. Therefore, we investigated the ability of RA to modulate the ability of tumor cells to recruit and activate monocytes for participation in VEGF-mediated angiogenesis and immunosuppression in vivo.

MATERIAL AND METHODS

Mice (ten/group) were injected daily with RA (160 microg/kg) for 3 weeks. After that time mice were sacrificed, and paraffin sections of tumors were obtained and stained for VEGF-A, CD68, and PECAM (CD31) by immunohistochemistry. The lungs, liver, and myocardium were analyzed for macro- and micrometastases. The plasma protein levels of VEGF-A and MCP-1 were determined by ELISA.

RESULTS

In RA-treated mice tumors regressed completely and RA prevented metastases (p=0.00) and macrophage infiltration (p=0.007). Treated mice downregulated VEGF-A (0 pg/ml) and MCP-1 (12 pg/ml) in peripheral blood (p=0.001).

CONCLUSION

Our findings suggest a new therapeutic possibility: the development of treatment protocols that can block each of the ways in which tumors induce new blood vessel growth and immunosuppression of the host.

[Multiple enterolithiasis, coexisting with bladder and gallbladder lithiasis, associated with colon adenocarcinoma]

Enteroliths are calculi primarily formed in the intestine. Enterolithiasis is a rare condition frequently associated with intestinal stasis. Usually it causes no symptoms in most cases, but it can be an important diagnostic clue in patients presenting intestinal occlusive symptoms. We report a case of multiple enterolithiasis, very infrequent pathology, coexisting with bladder and gall bladder lithiasis in a patient with colon adenocarcinoma. Diagnosis was made by X-rays and CT images. Calculi were analysed by several methods: chemical, infrared spectroscopy, stereoscopic microscopy and atomic emission spectroscopy; they showed that caluli are made up of organic material and whilokita (calcium and magnesium ortophosphate). No risk factors for lithogenesis were found in this patient excluding the intestinal stasis caused by intestinal narrowing as a result of adenocarcinoma. Genetic factors are suggested as main contributors to hyperlithogenesis observed in this patient. The physiopathological conditions were studied in depth and literature about this subject reviewed.

Formation of Cartilage in Congenital Bicuspid Aortic Valves of Syrian Hamsters (Mesocricetus auratus)

The formation, topographical location and calcification of cartilage in congenital bicuspid aortic valves of 235 Syrian hamsters aged 0--173 days were studied by histological, histochemical and immunohistochemical techniques. In all animals the aortic valve was bicuspid; it had two leaflets, ventral and dorsal, each supported by its own aortic sinus. In 141 valves, a more or less developed raphe was located in the ventral sinus. The remaining 94 valves were devoid of any raphe. The first sign of valvular chondrogenesis was the presence of small groups of cells embedded in a type II collagen-positive extracellular matrix. These cellular groups, which appeared as early as 2 days after birth, became converted into hyaline cartilage or fibrocartilage. A considerable proportion (67%) of the valvular cartilages developed within the first 6 weeks of life. The cartilaginous tissue was capable of forming anywhere along the attachments of the valve leaflets to their supporting sinuses. However, statistical analyses substantiated the observation that the bases of the sinuses and raphes were the valvular regions particularly prone to the development of cartilage. At these sites, the cartilage was usually hyaline and often became calcified. The findings were consistent with the assumption that intense mechanical stimulation plays an important role in the formation of the valvular cartilage. Moreover, these findings supplied new evidence that in the cardiac semilunar valves of Syrian hamsters, cartilage formation does not involve the aggregation of large numbers of cells before their differentiation into chondrocytes. The valvular hyaline cartilages appear to act as competent pivots, resisting mechanical tensions generated during the cardiac cycle. Deposition of calcium in the matrix can be regarded as a reinforcement process of the cartilaginous tissue. Finally, it is hypothesized that the formation of cartilage in the aortic valves of hamsters prevents dystrophic calcification of the valve, a pathological change that causes aortic stenosis in man, especially in patients with a bicuspid aortic valve.

Biorational approaches for insect control by enzymatic inhibition

Conventional insecticides are highly toxic to many living organisms as well as to the environment; consequently, new biorational and more specific approaches to pest control have been developed. In this paper, we present an update of those approaches resulting from studies on inhibition of enzymes involved in key processes of insects life, particularly growth, molting and development of larvae and intraspecific communication of adults. The enzymes covered include pheromone degrading enzymes, pheromone biosynthetic enzymes, oxidoreductases, juvenile hormones, juvenile hormone epoxide hydrolases, proteases, molting hormones and phenoloxidases. Although these approaches refer to control of insect pests, many of them can be in principle also considered suitable for medicinal chemistry studies, since the mechanism of action of these inhibitors on related enzymes is quite similar, if not equal, in both fields.

Antagonism of pheromone response of Ostrinia nubilalis males and implications on behavior in the laboratory and in the field

The antagonistic effect on the pheromone response and catabolism of male European corn borers, Ostrinia nubilalis, by several trifluoromethyl ketones is reported. (Z)-11-Tetradecenyl trifluoromethyl ketone (Z11-14:TFMK), the most closely related analogue of the main component of the pheromone, elicits a remarkable disruptive effect on close approach and source contact of males flying to a source baited with mixtures of the pheromone and the antagonist in 5:1 and 10:1 ratios. In this experiment, the male displayed an erratic flight track with frequent counter turns and intersections with the plume. In the field, the TFMK significantly lowered the number of males caught when mixed with the pheromone in a 10:1 ratio in comparison with the natural attractant. The compound was also a good inhibitor of the antennal esterase of the insect with a IC(50) value of 0.28 muM. The homologous (Z)-10-tridecenyl trifluoromethyl ketone, with one carbon less in the chain, also elicited an antagonistic effect in the wind tunnel, but in the field, the results were not conclusive. The effect induced was lower than the one displayed by Z11-14:TFMK including the activity as the esterase inhibitor (IC(50) value of 7.55 muM). The saturated tetradecyl trifluoromethyl ketone, tetradecyltrifluoropyruvamide, and (Z)-11-2-thiatetradecenyl trifluoromethyl ketone resulted completely inactive. The results obtained in conjunction to the previously shown low toxicity to mice by related trifluoromethyl ketones provide new important data for the putative utilization of these chemicals as new pest control agents.

New Selective Haloform-type Reaction Yielding 3-Hydroxy-2,2-difluoroacids: Theoretical Study of the Mechanism

Experimental results of an unprecedented haloform-type reaction in which 4-alkyl-4-hydroxy-3,3-difluoromethyl trifluoromethyl ketones undergo base-promoted selective cleavage of the CO-CF(3) bond, yielding 3-hydroxy-2,2-difluoroacids and fluoroform, are rationalized using DFT (B3LYP) calculations. The gas-phase addition of hydroxide ion to 1,1,1,3,3-pentafluoro-4-hydroxypentan-2-one (R) is found to be a barrierless process, yielding a tetrahedral intermediate (INT), involving a DeltaG(r)(298 K) of -61.4 kcal/mol. The CO-CF(3) bond cleavage in INT leads to a hydrogen-bonded [CH(3)CHOHCF(2)CO(2)H...CF(3)](-) complex by passage through a transition structure (TS1) with a DeltaG()(298 K) of 20.8 kcal/mol and a DeltaG(r)(298 K) of 9.8 kcal/mol. This complex undergoes a proton transfer between its components, yielding a hydrogen-bonded [CH(3)CHOHCF(2)CO(2)...CHF(3)](-) complex. This process has associated with it a DeltaG()(298 K) of only 3.1 kcal/mol and a DeltaG(r)(298 K) of -43.3 kcal/mol. The CO-CF(2) bond cleavage in INT leads to a hydrogen-bonded [CH(3)CHOHCF(2)...CF(3)CO(2)H](-) complex by passage through a transition structure (TS3) with a DeltaG()(298 K) of 29.2 kcal/mol and a DeltaG(r)(298 K) of 25.1 kcal/mol. The lower energy barrier found for CO-CF(3) bond cleavage in INT is ascribed to the larger number of fluorine atoms stabilizing the negative charge accumulated on the CF(3) moiety of TS1, as compared to the number of fluorine atoms stabilizing the negative charge on the CH(3)CHOHCF(2) moiety of TS3. The solvent-induced effects on the two pathways, introduced within the SCRF formalism through PCM calculations, do not reverse the predicted preference of the CO-CF(3) over the CO-CF(2) bond cleavage of R in the gas phase.

[Guidelines for the management of community pneumonia in adult who needs hospitalization]

Community acquired pneumonia is still an important health problem. In Spain the year incidence is 162 cases per 100,000 inhabitants with 53,000 hospital admission costing 115 millions of euros per year. In the last years there have been significant advances in the knowledge of: aetiology, diagnostic tools, treatment alternatives and antibiotic resistance. The Spanish Societies of Intensive and Critical Care (SEMICYUC), Infectious Diseases and Clinical Microbiology (SEIMC) and Pulmonology and Thoracic Surgery (SEPAR) have produced these evidence-based Guidelines for the management of community acquired pneumonia in Adults. The main objective is to help physicians to make decisions about this disease. The different points that have been developed are: aetiology, diagnosis, treatment and prevention.

[Octreotide in the treatment of angiodysplasia in patients with advanced chronic renal failure]

Angiodysplasia is an important cause of gastrointestinal bleeding in patients with chronic renal failure. Octreotide, a long-acting synthetic somatostatin analogue that reduces splachnic blood flow have been used to treat esophageal varicose hemorrhage, but its efficacy for bleeding vascular ecstasies is awaiting support. We present three patients with chronic renal failure (two with diabetic nephropaty and the third with mesangiocapilar glomerulonephritis and hepatic cirrosis), seric creatinine 3-4,5 mg/dl, and recurrent gastrointestinal bleeding due to diffuse angiodysplasia and vascular ecstasies, diagnosed by oral endoscopy, colonoscopy and video capsule. They all were treated with octreotide, administered subcutanesly 0.1 mg twice a day for six months, with significantly decreased blood requirements in all of them, as well as the occurrence of bleeding episodes. It was well tolerated and none side-effects occurred in any subject. In our experience, octreotide is an effective and safe drug in bleeding angiodysplasia and ecstasies vascular of the gastrointestinal tract in patients with chronic renal failure, and it may be a good option especially in patients who are not candidates for surgery or endoscopic treatment due to inaccessible sites, spread of the lesion, old age and/or concomitant disorders.

Protective effect of triflusal and its main metabolite HTB in an in vitro model of anoxia-reoxygenation in rat brain slices: comparison with acetylsalicylic and salicylic acids

Triflusal is a fluorinated derivative of acetylsalicylic acid (ASA) with demonstrated antithrombotic activity. Recently, evidence for a neuroprotective effect has been obtained. The aim of this study was to compare the neuroprotective effects of the main metabolite of triflusal (2-hydroxy-4-trifluoromethylbenzoic acid, HTB) and the ASA metabolite salicylic acid (SA) in an in vitro model of anoxia-reoxygenation in rat brain slices. Rat brain slices (n=10 per group) were subjected to a period of anoxia followed by 180 min reoxygenation. We measured oxidative stress parameters (lipid peroxidation, glutathione system), prostaglandins (PGE(2)), nitric oxide pathway activity (NO) (nitrites+nitrates, constitutive and inducible NO synthase activity) and LDH efflux, a biochemical marker of cell death. Various concentrations (10, 100 and 1,000 microM) of triflusal, HTB, ASA or SA were tested. Triflusal at 10, 100 and 1,000 microM decreased LDH efflux in rat brain slices after anoxia/reoxygenation by 24%, 35% and 49% respectively. This effect was proportionately greater than that of ASA (0%, 13% and 32%). The results with HTB were similar to those with triflusal, whereas SA showed a greater protective effect than ASA (13%, 33% and 35%). The antioxidant effects of HTB and SA on the biochemical mechanisms of cell damage studied here were also greater than the effects of triflusal and ASA, a finding attributable mainly to the decrease in lipid peroxidation and to the ability of HTB to also increase glutathione levels. The triflusal metabolite reduced inducible NO synthase activity by 18%, 21% and 30%, whereas SA inhibited this activity by 9%, 17% and 23%. Triflusal and HTB led to greater increases in NO synthase than ASA or AS. In conclusion, the metabolite HTB plays an important role in the neuroprotective effect of triflusal, at least in the experimental model of anoxia-reoxygenation tested here.

Formation of cartilaginous foci in the central fibrous body of the heart in Syrian hamsters (Mesocricetus auratus)

The formation of cartilage in the mammalian heart has been studied in the aortic and pulmonary valves. The chondrogenetic process that takes place in the cardiac skeleton is still unknown. The present study was designed to illustrate the ontogeny of cartilaginous foci occurring in the central fibrous body of the Syrian hamster (Mesocricetus auratus) heart. Hearts from 472 animals aged 0-708 days were examined using histological, histochemical and immunohistochemical techniques. Cartilage was present in the central fibrous body of 118 (25%) specimens. A further 104 hamsters were used for the detection of calcific deposits in the central fibrous body. Six (5.8%) showed calcified cartilage. The first sign related to chondrogenesis was the presence of small groups of cells embedded in a type II collagen-positive extracellular matrix. These cellular groups, which can appear as early as 2 days after birth, differentiate into hyaline cartilage or, less frequently, into fibrocartilage. The highest production of cartilaginous foci takes place between days 40 and 80. Thereafter, formation of new foci is uncommon. This indicates that appearance of cartilage in the central fibrous body of the heart is not a consequence of cardiac aging. The cartilaginous foci seem to act as pivots resisting mechanical tensions generated during the cardiac cycle. Deposition of calcium in the extracellular matrix of the foci can be regarded as a reinforcement of the cartilaginous tissue.

Enzyme inhibitors in biorational approaches for pest control

Conventional insecticides of broad spectrum have been widely used as the main tools for controlling insect pests. However, as the consequence of their toxicity and deep environmental impact, new biorational, and more specific approaches have been developed. In this review we present an overview of those pest control approaches which have resulted from studies dealing with inhibition of the enzymes involved in the physiology, growth, molting, development and reproduction of insect pests. These approaches involve synthetic compounds from laboratory studies and natural chemicals present in the crop plants. Recent developments using inhibitors expressed in transgenic plants are also outlined.

Synthesis and biological activity of new potential agonists for the human adenosine A2A receptor

New adenosine derivatives have been synthesized and tested as putative agonists of adenosine receptors. Compounds 2-6 derive from the introduction of several types of substituents (electron donating, electron withdrawing, and halogens) in the para-position of the phenyl ring of the parent compound 1, and compound 7 lacks the hydroxyl group of amino alcohol 1. In radioligand binding assays using recombinant human A(1), A(2A), A(2B), and A(3) receptors, all compounds showed very low or negligible affinity for A(1) and A(2B) receptors but compounds 3, 5, and 7 displayed a remarkably potent affinity for the A(2A) receptor with K(i) values of 1-5 nM. Bromo derivative 3 displayed a selectivity A(1)/A(2A) = 62 and A(3)/A(2A) = 16 whereas the presence of a hydroxyl group (compound 5) improved the selectivity of A(1)/A(2A) and A(3)/A(2A) to 120- and 28-fold, respectively. When the methoxy derivative 4 lacks the hydroxyl group on the side chain (compound 7), the binding affinity for A(2A) is increased to 1 nM, improving selectivity ratios to 356- and 100-fold against A(1) and A(3), respectively. In Chinese hamster ovary cells transfected with human A(2A) and A(2B) receptors, most compounds showed a remarkable activity for the A(2A) receptor, except chloro derivative 2, with EC(50) values ranging from 1.4 to 8.8 nM. The compounds behaved as good A(2A) agonists, and all were more selective than 5'-(N-ethylcarboxamino)adenosine (NECA), with A(2B)/A(2A) ratios of cAMP accumulation ranging from 48 for compound 2 to 666 for compound 7 while the corresponding A(2B)/A(2A) ratio for NECA was only 9. Compounds 1, 3, 5, and 7 also displayed higher selectivities than NECA up to 100-fold in isolated aortas of rat and guinea pig. In guinea pig tracheal rings precontracted by carbachol, compounds 2 and 4 were more potent than adenosine (100-fold) and NECA (10-fold), whereas compounds 1 and 7 displayed similar effects to NECA. Pretreatment of the tracheal rings with A(2), A(2A), and A(2B) receptor antagonists 3,7-dimethyl-l-propargylxanthine, 8-(3-chlorostyryl)caffeine, and alloxazine produced a marked inhibition of the tracheal relaxations induced by compounds 1, 2, and 4, but none of the compounds showed selectivity toward any of the adenosine receptors.