Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range.

Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 µm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.

Changes in the number and volume of NPY and VIP neurons from periprostatic accessory vegetative ganglia in pre- and peripubertal rats. A stereological study.

The amount of neurons of periprostatic accessory ganglia in pre- and peripubertal rats was studied to ascertain whether the development of these autonomic ganglia is androgen-dependent. Stereological estimates of the volumes and number of neurons immunoreactive to protein gene product 9.5 (PGP 9.5), neuropeptide Y (NPY), and vasoactive intestinal polypeptide (VIP) were carried out. Immunostaining of androgen receptors (AR) in the ganglia was also performed. The ganglionic neurons from the two groups studied were immunoreactive to PGP 9.5, NPY, and VIP. Almost all the neurons were immunostained for AR. The ganglionic volume showed a significant increase in peripubertal prostate in comparison with the prepubertal gland. No significant changes were observed with respect to the absolute number of neurons immunoreactive to all the antigens. The neuronal volume was significantly increased in peripubertal rats in comparison with prepubertal animals. These findings led us to the following conclusions: There is no evidence of neurogenesis during pubertal development in the periprostatic accessory ganglia of the rat. The increase of ganglionic volume in puberty is due to the growth in neuronal volume. There were no differences between the sizes of NPY and VIP neurons in pubertal periprostatic accessory ganglia. The development of periprostatic vegetative neurons is androgen-dependent.

[Scintigraphic study of gastric emptying of rehydration drinks in athletes]. / Estudio gammagráfico del ritmo de vaciado gástrico de bebidas de reposición en deportistas.

UNLABELLED: This study aims to evaluate how rehydration beverage ingestion influences gastric emptying rate (in cycle ergometer) at rest and during exercise at 70 % of maximal oxygen consumption (VO2max). MATERIAL AND METHOD: 26 well-trained cyclists performed a preliminary maximal test until exhaustion to evaluate their VO2max, and two submaximal exercise tests at 70 % of their mode-specific VO2max. Each test was separated by one week. During the two submaximal tests, cyclists consumed 200 ml of a 99mTc-DTPA labeled rehydration beverage (A or B) and scintigraphy determinations were performed at rest. After, exercise was initiated for 60 minutes with an intake rate of 200 ml every 15 minutes, making gastric serial scintigraphy determinations. The difference regarding chemical composition between A and B drinks resides in the fact that drink A contains a smaller load in carbohydrates (10.3 g/100 ml versus 15.2 g/100 ml of B), proteins in form of serum milk and antioxidants in form of fruit juice. Both contain ions and vitamins. RESULTS: at rest, gastric count number was significantly reduced (p > 0.000) from 0 to 25 minutes for both A and B beverage. At the end of exercise (60 min), there was greater gastric retention for B beverage than for A, this difference being statistically significant (p < 0.031). CONCLUSIONS: The A beverage, a rehydration drink on the market with protein and antioxidants with fruit juice content, has a faster gastric emptying rate than the B sport beverage.

Biological activity of extracts from Catalpa bignonioides Walt. (Bignoniaceae).

Catalpa bignonioides Walt. (Bignoniaceae) is a species that belongs to a tropical family but has been introduced in many countries as ornamental. Although this plant is consumed by indigenous cultures of South America for medical uses, experimental studies of the biological properties of Catalpa bignonioides are lacking. The aim of this work was to study the biological activity of crude extracts from either pods, seeds or leaves of Catalpa bignonioides which were collected in Spain. Ethyl ether, butanolic and aqueous fractions of the pod extract were also prepared and studied. We have examined the antimicrobial activity against five bacteria and one yeast, the cytotoxic activity against HepG2 cells and the anti-inflammatory and antinociceptive effects in rodents. A preliminary phytochemical analysis of the extracts and fractions was also conducted. Results showed no antimicrobial or antitumoral effects, but prominent anti-inflammatory and antinociceptive actions of the extracts. These last activities may be a result of the presence of either of saponins, sterols or phenols, mainly found in the leaves and pods of the plants.

Immunolocalization of alkaloids and X-ray microanalysis of elements in lupin seeds.

Immunolocalization of alkaloids in lupin seeds (Lupinus spp.) has been performed by cryofixation and conventional methods. Alkaloids were localized in the protein bodies of the cotyledon cells. Some immunogold particles in the walls of these cells were also observed. There were no differences in the sites of localization between the two mentioned methods. X-ray microanalysis of elements showed the presence of P, Mg, S, and K in the protein bodies of cotyledon cells in lupin seeds. The role of K+ in alkaloids transport is discussed.

Tecoma sambucifolia: anti-inflammatory and antinociceptive activities, and 'in vitro' toxicity of extracts of the 'huarumo' of peruvian incas.

Aqueous and alcoholic extracts of pods and flowers of Tecoma sambucifolia H.B.K. (Bignoniaceae) ('huarumo') were analysed to determine their anti-inflammatory activity (carrageenan-induced edema test), antinociceptive activity (acetic acid writhing test) and 'in vitro' toxicity in Chinese hamster ovary cells, human hepatome cells and human larynx epidermal carcinoma cells. The cytotoxic effects of both extracts were evaluated by two endpoint systems: neutral red uptake assay and tetrazolium assay. The results showed that all extracts have anti-inflammatory and antinociceptive activity, but the highest potency is that of the alcoholic extracts. There were significant differences in cytotoxicity between extracts and among the response of cells to them. The highest cytotoxicity was noted with the alcoholic extract, and the human hepatome cell line was the most sensitive, especially to the alcoholic extract of flowers. The aqueous pod extract appeared to have the best pharmaco-toxicological profile, since it provided a significant reduction of both pain and inflammation together with the lowest cytotoxicity.

Evaluation of the toxicity of guarana with in vitro bioassays.

A natural stimulant, Paullinia cupana, commonly called guarana, was tested for its ability to induce in vitro toxicity in Chinese hamster ovary (CHO) cells and bacterial cells (Photobacterium phosphoreum). The cytotoxic effects of aqueous guarana extracts were evaluated by three endpoint systems: neutral red (NR) uptake assay, total protein content [kenacid blue (KB)] assay, and tetrazolium (MTT) assay. The Microtox test was also used. Results indicated that the lowest concentration of guarana tested was not toxic and that the IC50 values calculated with the NR, KB, and MTT assays were lower than the highest concentration tested (40 mg/ml). There was no significant difference in cytotoxicity between the three test systems. The EC50 values obtained with the Microtox assay were consistent with these data. The present in vitro analysis suggests that the concentration of guarana is of critical importance in its cytotoxic activity and high doses could be harmful to human health.

Molecular Mechanics Study of the Inclusion Complexes of 2-Methyl Naphthoate with alpha- and beta-Cyclodextrins

Molecular mechanics calculations were employed to study the inclusion of 2-methyl naphthoate in alpha- and beta-cyclodextrin in vacuo and in the presence of water as a solvent. The driving forces for complexation are dominated by nonbonded van der Waals host:guest interactions in both environments. The 2-methyl naphthoate penetrates completely into the cavity of beta-cyclodextrin, but there is only partial penetration by the same molecule into the smaller cavity of alpha-cyclodextrin. Copyright 1997Academic Press

Evaluation of the toxicity of Uncaria tomentosa by bioassays in vitro.

Aqueous extracts of Uncaria tomentosa (Willdenow ex Roemer and Schultes) DC. (Rubiaceae) ('Uña de gato'), were analyzed for the presence of toxic compounds in Chinese hamster ovary cells (CHO) and bacterial cells (Photobacterium phosphoreum). Toxicity was evaluated by four systems: Neutral red assay (NR), total protein content (KB), tetrazolium assay (MTT) and Microtox test. The extracts of U. tomentosa did not show toxicity in vitro at the concentrations tested. Testing in vitro could be a valuable tool for evaluating toxicity of medicinal plants.

Toxicity of potential irritants in mammalian cells in vitro.

Four bioactive materials were tested for their ability to produce toxicity in vitro in two cell lines: rabbit corneal cells (SIRC) and human fibroblasts. These compounds are widely used by industries, causing toxic effects to ecosystems and particularly having an impact on human health. Different chemicals were chosen which were structurally unrelated: triethanolamine, zinc pyrithione, sodium lauryl sulfate, and oleamine. Cytotoxicity was evaluated measuring the total protein content (inhibition of cell growth). Results indicated that zinc pyrithione produced the highest inhibition of cell growth when two cell lines were treated in the two doses tested. The lowest cytotoxic effect was observed with oleamine. Triethanolamine and sodium lauryl sulfate produced a similar cytotoxic effect in Fe cells, although sodium lauryl sulfate revealed higher inhibition of cell growth than triethanolamine on SIRC cells. From these results, it can be concluded that some products as triethanolamine and zinc pyrithione should be observed in future special toxicological studies.

Cytotoxicity and mutagenicity of 6-aminonicotinamide in Chinese hamster ovary cells.

A strong teratogen-6-aminonicotinamide (6-AN)-was tested for its ability to induce cytotoxicity and mutagenicity in Chinese hamster ovary (CHO) cells. Tests were performed in the presence and absence of a metabolic activation system (S-9 mix). Cytotoxicity was evaluated in CHO cells by the total protein content. The two single-gene mutation systems in CHO cells have been investigated. Both involve evaluating the response of the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus and specific inhibitors of the cellular (Na2+K+)-ATPase using 6-thioguanine and ouabain as selective agents, respectively. From our results, 6-AN showed a higher cytotoxic effect at concentrations over 1 x 10(-1) mg/ml. Cytotoxicity was significantly different with and without S-9 mix. 6-AN was cytotoxic per se, however, when 6-AN was biotransformed, in the presence of S-9 mix no biological activity (cytotoxic) was detected. Non-significant mutagenic activity was detected with 6-AN in the presence and in the absence of the metabolic activation system.

Adsorption and mobility of acephate in soils.

The influence of soil properties on the adsorption and mobility of acephate (O, S-dimethylacetylphosphoroamidothioate) was studied. The Freundlich adsorption constant (K) and the distribution coefficient (Kd) were found to be highly correlated (P < 0.001) with the silt + clay content of the soil, both for the studied soils as a whole and for those with organic matter contents below 2%. The mobility of acephate as determined by thin-layer chromatography (saturated flow conditions) was found to be Rf = 1 for all soils except the three with a high silt + clay content, whose Rf was smaller than unity. A study of the acephate mobility in soil-packed columns under unsaturated flow conditions revealed that the highest proportion of the insecticide was retained at the top of the columns; also, the insecticide distribution in the columns and the overall amounts retained and leached were related to the silt+clay content of the soils.

Magnesium deficiency results in increased suberization in endodermis and hypodermis of corn roots.

The composition of the aliphatic components of suberin in the stele and cortex of young corn (Zea mays L.) roots was determined by combined gas-liquid chromatography/mass spectrometry of the LiAlD(4) depolymerization products. omega-Hydroxy acids were shown to be the major class of the aliphatic components of both the hypodermal (35%) and endodermal (28%) polymeric materials with the dominant chain length being C(24) in the former and C(16) in the latter. Nitrobenzene oxidation of the roots generated p-hydroxybenzaldehyde and vanillin with much less syringaldehyde. Electron microscopic examination of the hypodermal and endodermal cell walls from roots of corn plants grown in a Mg(2+) -deficient (0.03 millimolar) nutrient solution showed that these walls were more heavily suberized than the analogous walls of roots from plants grown in normal (2 millimolar) Mg(2+) levels. Analysis of the LiAlD(4) depolymerization products of the suberin polymers from these roots showed that the roots grown in low Mg(2+) had 3.5 times as much aliphatic suberin monomers on a weight basis as the roots from plants grown in nutrient with normal Mg(2+) levels. Roots from plants grown in Mg(2+) -deficient nutrient solution released 3.8 times the amount of aromatic aldehydes upon nitrobenzene oxidation as that released from normal roots. As the degree of Mg(2+) deficiency of the nutrient solution was increased, there was an increase in the aliphatic and aromatic components characteristic of suberin. Thus, both ultrastructural and chemical evidence strongly suggested that Mg(2+) deficiency resulted in increased suberization of the cell walls of both hypodermis and endodermis of Zea mays roots. The roots from Mg(2+) -deficient plants also had a higher amount of peroxidase activity when compared to control roots.

[Evaluation of gammagraphy in the differential diagnosis of cysts and renal tumors]. / Valoración de la gammagrafía en el diagnóstico diferencial de quistes y tumores renales.

In view of the problems posed by the diagnosis of intrarenal masses, the authors review 16 cases of patients with this pathology who have undergone renographic and gammagraphic studies. They obtain a high level of coincidence between the gammagraphic diagnosis and its subsequent surgical confirmation, a fact which indicates that the kidney gammagraph is of great diagnostic value. This may be due to the different vascularization of the pathological area which would allow for a greater indication by the tracer, rejecting the theory of parenchymatous intoxication by toxic tumour substances.