Comparison of biomechanical and structural properties between human aortic and pulmonary valve.

OBJECTIVE: Pulmonary valve autografts have been reported as clinically effective for replacement of diseased aortic valve (Ross procedure). Published data about pulmonary valve mechanical and structural suitability as a long-term substitute for aortic valve are limited. The aim of this study was to compare aortic and pulmonary valve properties. METHODS: Experimental studies of biomechanical properties and structure of aortic and pulmonary valves were carried out on pathologically unchanged human heart valves, collected from 11 cadaveric hearts. Biomechanical properties of 84 specimens (all valve elements: cusps, fibrous ring, commissures, sinotubular junction, sinuses) were investigated using uniaxial tensile tests. Ultrastructure was studied using transmission and scanning electron microscopy. RESULTS: Ultimate stress in circumferential direction for pulmonary valve cusps is higher than for aortic valve (2.78+/-1.05 and 1.74+/-0.29 MPa, respectively). Ultimate stress in radial direction for pulmonary and aortic cusps is practically the same (0.29+/-0.06 and 0.32+/-0.04 MPa, respectively). In ultrastructural study, different layout and density in each construction element are determined. The aortic and pulmonary valves have common ultrastructural properties. CONCLUSIONS: Mechanical differences between aortic and pulmonary valve are minimal. Ultrastructural studies show that the aortic and pulmonary valves have similar structural elements and architecture. This investigation suggests that the pulmonary valve can be considered mechanically and structurally suitable for use as an aortic valve replacement.     

Influence of abutment material on stability of peri-implant tissues: a systematic review

PURPOSE: The aim of this systematic review was to evaluate available evidence for a difference in the stability of peri-implant tissues between titanium abutments versus gold alloy, zirconium oxide, or aluminum oxide abutments. MATERIALS AND METHODS: Studies were identified by examining several electronic databases and major dental implant, prosthetic, and periodontal journals. To be selected for the preliminary article pool, the article must have been written in the English language and published from 1980 to March 2007. Articles were sorted based on the nature of the study. In vitro studies and literature reviews were excluded. The included articles were clinical, human histology, and animal studies. Case reports, case series, uncontrolled clinical trials, and clinical studies with teeth treated as a control were excluded from the final review. RESULTS: The initial article pool included 40 articles of which 9 met the inclusion criteria: 3 animal studies, 2 human histological studies, and 4 randomized clinical trials. Soft tissue recession was not accurately measured in the included clinical studies. Assessment of peri-implant tissues around zirconium oxide and titanium abutments was described only in animal and human histologic studies. Due to differences in study types, timing of follow-ups, and outcome variables, meta-analysis could not be performed. CONCLUSIONS: Included studies revealed that titanium abutments did not maintain a higher bone level in comparison to gold alloy, aluminum oxide, or zirconium oxide abutments. However, there is a lack of information about the clinical performance of zirconium oxide and gold alloy abutments as compared to titanium abutments.     

Relation of inflammatory chemokines to insulin resistance and hypoadiponectinemia in coronary artery disease patients

BackgroundAlthough many studies have shown that the metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) both are associated with chronic inflammatory state and are risk factors for coronary artery disease (CAD), it is still unclear which condition is a more important contributor to the increased production of inflammatory chemokines. The purpose of this study was to assess monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) levels and their association with insulin resistance and adiponectin concentrations in CAD patients, who were categorized as having T2DM, MS, or neither.MethodsCAD male patients were categorized into three groups: 24 non-obese patients with T2DM (D), 24 obese patients with MS (M) and 24 patients without T2DM or MS (W). 20 healthy subjects were selected as controls (C). Insulin resistance was assessed by the HOMA-IR method, but serum MCP-1, IL-8, and adiponectin levels were measured by xMAP technology.ResultsSerum levels of MCP-1 and IL-8 in D and M groups were increased in comparison with W and C groups (p < 0.001, p < 0.01), but the increase in the M group was significantly higher than that in the D group (p < 0.05, p < 0,001), besides MCP-1 and IL-8 concentrations were correlated with HOMA-IR indexes (r = 0.52; r = 0.49, p < 0.0001) and adiponectin levels (r = ? 0.59, p < 0.0001). The M group demonstrated a diminution in the adiponectin level (p < 0.01) and pronounced increase of HOMA-IR in comparison with the other three groups (p < 0.01).ConclusionObese CAD patients with MS have a more pronounced increase of MCP-1, IL-8 and HOMA-IR and more decreased adiponectin levels than non-obese CAD patients without MS.     

Arylsulfonamidothiazoles as a new class of potential antidiabetic drugs. Discovery of potent and selective inhibitors of the 11beta-hydroxysteroid dehydrogenase type 1

Novel antidiabetic arylsulfonamidothiazoles are presented that exert action through selective inhibition of the 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) enzyme, thereby attenuating hepatic gluconeogenesis. The diethylamide derivative 2a was shown to potently inhibit human 11beta-HSD1 (IC(50) = 52 nM), whereas the N-methylpiperazinamide analogue 2b only inhibited murine 11beta-HSD1 (IC(50) = 96 nM). Both compounds showed >200-fold selectivity over human and murine 11beta-HSD2. 2b was subsequently shown to reduce glucose levels in diabetic KKA(y) mice, substantiating the 11beta-HSD1 enzyme as a target for the treatment of type 2 diabetes.     

Potato (Solanum tuberosum) juice exerts an anticonvulsant effect in mice through binding to GABA receptors

Naturally occurring benzodiazepines have been identified in regular food such as wheat and potato, but there is still no evidence that potato extracts can affect CNS responses in vivo. Here we found that undiluted potato juice and potato juice diluted with saline 1 : 2 administered 10 min intracisternally ( I. C.) and 30 min per os before bicuculline exerted significant anticonvulsant activity in the bicuculline-induced seizure threshold test in mice. In vitro, potato juice from different harvests at dilution series from 10 % to 0.000001 %, diluted 100,000-fold, displaced 50 % of gamma-aminobutyric acid (GABA) receptor ligand [ (3)H]GABA and diluted 40-fold displaced 50 % of [(3)H]flunitrazepam from binding sites in mice forebrain membranes. The low content of diazepam (0.04 +/- 0.01 mg/kg) determined by HPLC and mass spectrometry in the potato extracts could not sustain the anticonvulsant activity of potato juice in vivo; therefore we hypothesized that potato juice might contain GABA (A) receptor GABA-site active compounds. The findings of this study suggest that potato juice as well as potato taken as food may have the capacity of influencing brain GABA-ergic activity.     

Scale-Up and Testing of Polyurethane Bio-Foams as Potential Cryogenic Insulation Materials

This article compares the properties of closed-cell PUR bio-foams produced on a laboratory scale and on an industrial scale. In the formulation used, the polyol premix contained 40 wt.% of a bio-polyol based on rapeseed oil. Selected useful properties of the foams obtained on the two scales and the use of one-step and spraying methods were compared. In the case of the spraying method, the experimental system was compared to a commercial one. Given the possibility of applying the bio-foams in insulation systems for cryogenic and liquefied natural gas (LNG) applications, a compressive strength analysis of the foams was carried out at room temperature as well as at −196 °C. It was found that the foams modified with the bio-polyol were characterized by a higher compressive strength at low temperatures than commercial foams based on a petrochemical polyol.     

The effect of 2 different diameter cast posts on tooth root fracture resistance in vitro

Prosthetic treatment frequently involves the restoration of endodontically treated teeth (ETT), which in turn implies that there has been a reduction of the crown due to previous restorative treatment, trauma and/or endodontic manipulations. The prognosis of a restored ETT is very much dependent on pre-endodontic status of the tooth, the quality of the endodontic treatment, the amount remaining tooth structure and the bone support. The aim of this study is to measure fracture resistance of extracted premolar teeth restored with 2 different diameter posts. Extracted premolars were collected and stored in physiologic solution at 5 degrees C. The teeth were examined for fractures by direct and transillumination observation and 40 premolars were accepted for the study. The PC were modelled using the appropriate diameter plastic pattern for the post and Pattern Resin (GC) was used to model the core part of the PC. The PC patterns were invested and cast in cobalt chromium alloy and then cemented using zinc phosphate cement. Fracture resistances of the samples were tested in an "Instron 4301" (Instron Series IX Automated Material Testing System Version 5) with a loading speed of 0.5 mm/min. The data for each sample was recorded graphically. Both groups were analyzed using the t-test (p<0.01) in relationship to the mean value of that group. Post and cores significantly reduce the fracture resistance of the tooth and should be used only to secure retention and resistance form for full coverage crowns. Teeth with a larger diameter post have a reduced fracture resistance than teeth with a smaller diameter.     

Role of adenosine 3′,5′-cyclic monophosphate in adrenoceptor-mediated control of 3H-noradrenaline secretion in guinea-pig ileum myenteric nerve terminals

Secretion of 3H-noradrenaline was evoked by electrical field stimulation (1 Hz, 300 shocks) in guinea-pig ileum myenteric plexus. The role of cyclic nucleotides in the presynaptic receptor-mediated control of 3H-noradrenaline secretion was studied. The secretion of 3H-noradrenaline was maximally enhanced to the same extent, viz. 300-400% of control, by two analogues of cyclic AMP (8-Br cyclic AMP and dibutyryl cyclic AMP), by an adenylate cyclase activator (forskolin) and by three structurally different inhibitors of phosphodiesterase (3-isobutyl-1-methylxanthine, SQ 20,006 and Ro 20-1724), but not altered by two analogues of cyclic GMP (8-Br cyclic GMP and dibutyryl cyclic GMP). Added separately an alpha 2-adrenoceptor antagonist (yohimbine) and a beta-adrenoceptor agonist (isoprenaline) enhanced the 3H-noradrenaline secretion. Yohimbine, but not isoprenaline, increased additively the 'maximal enhancement' of the 3H-noradrenaline secretion caused by 3-isobutyl-1-methylxanthine. These results suggest that neuronal cyclic AMP may be involved in beta- but not in alpha-adrenoceptor-mediated control of 3H-noradrenaline secretion in guinea-pig ileum myenteric nerve terminals.