Preparation and electrical characterization of poly(vinyl amine) hydrogels,crosslinked with Cu(II) ions,and evaluation of their potentiality as water sensor material

A method to prepare water sensitive composites employing crosslinked poly(vinyl amine) (PVAm) and Cu(II) ions as reticulation agent is disclosed in this work. This article presents in detail, the reticulation reaction and its pH dependence, as well as its electrical, rheological, and thermal properties of the PVAm‐Cu(II) composites obtained. The complex bonds formed between the Cu(II) ions and the amine groups of PVAm produce an interesting network of crosslinked structures that generate a microporous morphology when the material is extruded. This characteristic favors fast absorption of water when it is wetted, and a concomitant decrease in its apparent resistivity in a very short period of time. Furthermore, they present an excellent thermal stability and suitable processability. These characteristics make them interesting candidates to design ultra fast water sensors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Asymmetric bihomologous crosslinkers for bicomponent gels—The way to strongly increased elastic moduli

2‐Hydroxyethylmethacrylate (HEMA) and acrylamide (AA) have been copolymerized via free radical mechanism, in the presence of 5 mol % of four different crosslinker systems, the symmetric ethylenglycoldimethacrylate (EGDMA), bisacrylamide (BIS), a mixture of EGDMA and BIS, and the asymmetric acrylamideethylenmethacrylate (METAA). The polymerizations have been monitored with a rheometer, exhibiting the gel obtained with the asymmetric METAA, an elastic modulus that is dramatically increased compared with those of the gels prepared with the other three crosslinker systems. A kinetic analysis using the terminal model has been used to build probabilistic surfaces that give information about how the crosslinker is incorporated into the network. This analysis shows a high dissimilarity between the reactions using the asymmetric and the mixture of symmetric crosslinkers, what has been correlated to the difference in modulus. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Acute effect of 17 beta-estradiol and lithium on ovariectomized rat brain biogenic amines metabolism

The effect of 17 beta-estradiol (E2) on the response of dopamine (DA) and serotonin (5-HT) to acute lithium in the brains of ovariectomized rats was investigated. An E2 injection (100 ng/s.c.) to ovariectomized rats did not change striatal DA levels, whereas the levels of its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), increased 30 min later; concentrations of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), also remained unchanged. In the frontal cortex, DA, 5-HT, HVA and 5-HIAA levels remained unchanged after the E2 injection, whereas DOPAC levels and DOPAC/DA and HVA/DA ratios increased 30 min later. Injection of LiCl (10 mEq) decreased striatal DA levels, increased DOPAC levels and slightly decreased HVA levels; by contrast, frontal cortex DA and HVA levels increased but DOPAC levels were unchanged. A biphasic response of striatal 5-HT levels occurred, increasing shortly after injection of LiCl, followed by a decrease; 5-HIAA levels, however, increased. In the frontal cortex, injection of rats with LiCl led to a gradual increase in 5-HT levels, whereas 5-HIAA concentrations decreased. In the presence of E2, LiCl effected a greater decrease in striatal DA than injection of LiCl alone, advanced the DOPAC peak by 30 min and increased HVA levels; E2 had less effect on the 5-HT response to LiCl, except the decreases in 5-HT and 5-HIAA at 60 min were greater. Furthermore, in the striatum, the increased DA turnover caused by LiCl, estimated by the DOPAC/DA and HVA/DA ratios, was advanced in rats treated with E2. In the presence of E2, LiCl slightly increased frontal cortex DA, DOPAC and HVA levels compared with treatment with LiCl alone, whereas DOPAC levels decreased in rats treated with LiCl + E2 compared with levels in E2-treated rats. Generally, higher levels of 5-HT and 5-HIAA were measured in the frontal cortices of rats treated with LiCl + Ex compared with rats injected with LiCl. These results indicate that E2 potentiates the acute effect of lithium on striatal and frontal cortex DA and 5-HT levels and metabolism, suggesting a role of the hormonal state on this drug response.     

Developmental and behavioral effects of prenatal primidone exposure in the rat

Pregnant Sprague-Dawley rats were administered primidone (PRM) by oral gavage on gestation days 8-17 in doses of 0.40, and 80 mg/kg. Although these doses of PRM did not produce significant differences in litter size, birth weight, mortality, date of attainment of developmental landmarks or measures of preweaning reflex and motor development, there were a number of significant differences that developed as the animals approached and entered adulthood. When tested as adults, the 80 mg/kg male rats showed a deficit in the performance of an eight-arm radial maze task. These same animals showed a significant reduction in open field activity when tested as adults. In addition, both male and female PRM-treated animals showed reduced body weights at different periods corresponding to onset of sexual maturation during development. These findings are consistent with the larger body of literature reporting on the neurobehavioral teratology of phenobarbital, including its ability to produce lesions in the hippocampus and endocrine dysfunction resulting in reproductive deficits. These results suggest that PRM produces its adverse effects as a result of its metabolism to phenobarbital, which in turn affects the limbic system.     

Endoscopic hemostasis in bleeding gastroduodenal ulcer--a contribution to the cost aspect

Endoscopic injections of fibrin glue for the treatment of gastroduodenal ulcer hemorrhage have been increasingly used instead of sclerosing agents since 1987. Sclerosants have the drawback that they themselves have tissue-destroying or rather ulcerogenic effects. A difficult form of administration and a relatively high price are set against the good biological properties of the fibrin glue. In a randomized study comparing fibrin glue with polidocanol there was a statistically significant lower rebleeding rate in the fibrin group. The data of this study were analysed with regard to economic aspects. They showed an improved cost-benefit and cost-effectiveness ratio of the fibrin glue compared with polidocanol.     

The effect of hallux sesamoid excision on the flexor hallucis longus moment arm

Surgical treatments for chronic, painful hallux sesamoid disorders typically involve partial or complete resection of 1 or both sesamoids. Although these approaches generally result in satisfactory symptom relief, their effect on biomechanical function of the major hallux flexors is not completely understood. The effects of selective sesamoid resections on the effective tendon moment arm of the flexor hallucis longus tendon were evaluated. Twelve fresh frozen cadaver first rays were each mounted in a device that held rigid the metatarsal. A ramp-controlled displacement of an MTS ram supplied a functional load input force to the flexor hallucis longus. The components of the resultant output force necessary to resist the input flexor hallucis longus force were transduced simultaneously by a multicomponent load cell. Subsequently, 3 progressively more extensive seasamoid resections were done: (1) distal hemiresection, (2) complete resection, and (3) resection of both sesamoids. Six specimens were tested with the medial sesamoid removed first and 6 with the lateral sesamoid removed first. Statistical analysis showed that significant decreases in the effective tendon moment arms occurred with full medial sesamoid resection, full lateral sesamoid resection, and resection of both the medial and lateral sesamoids.     

Legal issues in sharing the benefits of biodiversity prospecting

The National Cancer Institute (NCI) is the US Government's principal agency for research on the prevention, diagnosis and treatment of cancer. A critical component of the Institute's mission is the identification and development of new and promising treatments for cancer and AIDS. For many years these efforts have included a program to investigate natural products for potential new therapeutic agents. In 1986, with the advent of new screening techniques, the National Cancer Institute stepped up its exploration of natural products and began world-wide collections of plants in tropical and subtropical regions. In recognition of the principles of the Biodiversity Treaty, NCI appreciates that continued access to the natural products of these countries depends on the Institute's ability to recognize the contributions of these source countries and their indigenous peoples, and to provide them adequate incentives to conserve their natural resources for the purposes of drug discovery. Accomplishing this goal presented several legal issues for the National Cancer Institute. As an agency of the US government, the NCI has an adjunct statutory mission to facilitate the transfer of technology developed through the Institute's programs into the private sector for further development and commercialization, and NCI operates under a national policy to use the patent system to transfer Federally supported research to the private domestic sector. Reliance on patent law may limit the Institute's ability to recognize the rights of source countries and their indigenous people and provide compensation for their contributions. However, other legal instruments, such as contracts, can serve as interim measures to provide compensation to source countries and indigenous populations. The National Cancer Institute's Letter of Collection agreement (LOC, formerly the "Letter of Intent'), is an example of an alternative means that "fills-in the gaps' created by patent law and through which source countries may share in the benefits of natural product development.     

Efficiency of lysine or threonine retention in growing rats fed diets limiting in either lysine or threonine

Over a 21-d experiment, the efficiency of lysine and threonine retention was determined in 80 male Sprague-Dawley rats (65.9 +/- 0.3 g, means +/- SE) fed purified diets containing an amino acid mix limiting in either lysine or threonine. With additional increments of the first limiting amino acid, lysine concentration in total body protein (g/16 g N) increased (P < 0.01) in rats fed lysine-limiting diets but, when fed threonine-limiting diets, lysine concentration in body protein first increased and then decreased (P < 0.01). As increments of the first limiting amino acid were added, the threonine concentration in total body protein increased then decreased when both lysine- (P < 0.01) and threonine- (P < 0.06) limiting diets were fed. Lysine and threonine retention were calculated based on comparative slaughter. Sixteen rats were killed on d 0 to estimate the grams of amino acid in the body. Retention responses were analyzed using a logistic equation in which lysine or threonine intake was used to predict retention. The maximum marginal efficiency (dr/dI, retention/intake) was observed at <40% of maximum retention. For lysine retention, it was 81% when lysine was limiting and 70% when threonine was limiting. For threonine retention, it was 58% when threonine was limiting and 49% when lysine was limiting. The maximum cumulative efficiency (retention adjusted for maintenance relative to cumulative intake) for lysine retention was 62% when lysine was limiting or 58% when threonine was limiting. For threonine retention, it was 51% when threonine was limiting and 35% when lysine was limiting. Thus, amino acid concentration in body protein is not constant, and amino acids are used with higher efficiency when first limiting.     

Relation between insulin-like growth factor-I concentrations, osteoarthritis, bone density, and fractures in the general population: the Chingford study

OBJECTIVE: To assess the association between serum insulin-like growth factor-I (IGF-1) concentrations and osteoarthritis, and bone mineral density, and fractures in a large group of middle aged women from the general population. METHODS: 761 women aged 44-64 years from the Chingford study had serum IGF-I concentrations measured; hand, hip, spine, and anteroposterior weight bearing knee radiographs taken; and dual energy x ray absorptiometry (DEXA) scans of the hip and spine. X rays were scored using the Kellgren and Lawrence system. In addition knee x rays were scored using a standard atlas for individual features of osteophytes and joint space narrowing (both graded 0-3). IGF-I concentrations were adjusted for the effects of age. RESULTS: In the osteoarthritis analysis results were compared to a constant group of 155 subjects with no evidence of osteoarthritis at any site. There was no significant difference in serum IGF-I between these subjects and 606 subjects with osteoarthritis at any site. When individual sites were analysed, serum IGF-I was higher in those cases with more severe bilateral knee osteoarthritis and in those with distal interphalangeal (DIP) joint disease. There was no significant association between serum IGF-I and other forms of osteoarthritis or milder forms of knee osteoarthritis. There was no correlation between IGF-I concentrations and bone mineral density at the spine or hip, nor any difference between IGF-I concentrations in subjects with and without a history of non-traumatic fracture [22.8 (SD 6.6) v 23.1 (SD 6.6) nmol litre-1, P = 0.6] CONCLUSIONS: There is a modest association between IGF-I concentrations and the development of DIP osteoarthritis and more severe or bilateral knee joint osteoarthritis in women from the normal population, but no association with other forms of osteoarthritis, bone density, or fractures.