Determination of the total attenuation coefficient for six contact lens materials using the Beer-Lambert law

The Beer-Lambert law has been used to determine the total attenuation coefficient, mu t, of three hard and three soft contact lens materials. The three hard contact lens materials were PMMA, Polycon II and Boston IV whereas the 3 soft materials were chosen with differing water contents of 38, 55 and 70%, respectively. The total attenuation coefficients of all six materials were obtained from measurements of the axial transmission at 632.8 nm of a series of plano powered lenses varying in axial thickness from 0.5 to 3.5 mm. The value of the total attenuation coefficient depends on both scattering and absorption and hence PMMA and Boston IV, which both incorporated a handling tint, showed significantly higher values (P < 0.0001) of mu t (0.562 +/- 0.010 mm-1 and 0.820 +/- 0.008 mm-1, respectively) than Polycon II (mu t = 0.025 +/- 0.005 mm-1). A comparison between Polycon II and the three hydrated soft contact lens materials showed a significant increase (P < 0.02) in the total attenuation coefficients for the 38% and 55% water content materials, and a weakly significant increase for the 70% water content soft lens material (P < 0.1). On the assumption that the absorption coefficients of these four materials are approximately constant, then this change would be due to an increase in the scattering coefficient of the material and could contribute to an increase in intraocular scatter. No significant difference (P > 0.5) was found between any of the hydrated soft contact lens materials tested.     

Demonstration of delayed hypersensitivity in Chlamydia trachomatis salpingitis in monkeys: a pathogenic mechanism of tubal damage

The role of delayed hypersensitivity in the pathogenesis of Chlamydia t trachomatis salpingitis was studied in the monkey "pocket" model. Pigtailed monkeys (Macaca nemestrina) were sensitized by inoculation of live C. trachomatis organisms (E/UW-5/Cx) into subcutaneous pockets containing salpingeal autotransplants. At 21 days, affinity-purified recombinant C. trachomatis heat-shock protein (rhsp60) was injected into pockets either previously sensitized with C. trachomatis or not sensitized in the same monkey. Delayed-type hypersensitivity reaction was observed, characterized by mononuclear cell infiltration with peak reaction at 48 h. Injection of rhsp60 into the pockets of a naive animal did not induce inflammation. This study showed that C. trachomatis infection in monkeys induced delayed hypersensitivity, which is mediated by hsp60. Histologic findings of the salpinx were consistent with delayed hypersensitivity reaction observed in ocular C. trachomatis infection, further suggesting a similar pathogenesis for both salpingitis and trachoma.     

The Influence of Adherend Topography on the Fracture Toughness of Aluminium-Epoxy Adhesive Joints in Humid Environments

The adherend surface topography has a dramatic effect on the durability of structural bonds formed between aluminium and an epoxy adhesive. Systematic changes in the micro-roughness of an aluminium adherend were achieved using an ultra-milling technique to prepare surfaces with topographies ranging from ultra-flat to a sawtooth profile with a base angle of approximately 60° and a peak-to-valley depth of 10 μm. The fracture toughness of double-cantilever beam specimens, stressed in the Mode 1 direction and exposed to a humid environment was found to change by a factor of approximately one hundred as the sawtooth profile angle was increased. These changes in fracture toughness may be accounted for through complex interrelationships between moisture diffusion and interphase mechanical properties, each with a strong dependence on the surface micro-topography.     

The efficacy of oral appliances in the treatment of persistent sleep apnea after uvulopalatopharyngoplasty

Twenty-four patients who failed uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea (OSA) had an adjustable oral (Herbst) appliance made to treat the persistent apnea. Six patients discontinued the device prior to sleep evaluation. Eighteen patients had polysomnographic evaluations at baseline, post-UPPP, and with the Herbst appliance in place. The apnea-hypopnea index baseline (AHI) and arterial oxygen saturation (SaO2) nadir were 42.3+/-6.1 and 83.6+/-1.8%, respectively. There was no significant change in either parameter with surgery. With the oral appliance, the AHI fell to 15.3+/-4.4 (p < or = 0.01) and the SaO2 nadir increased to 87.9+/-1.2% (p < or = 0.05). Ten of the patients had control of the OSA with the Herbst appliance with a fall in the AHI to < 10. There were, in addition, two partial responders as defined by an AHI of <20 and a >50% fall in AHI compared with baseline and post-UPPP values. All but one of the responders and partial responders had complete resolution of subjective symptoms of daytime sleepiness with the appliance. An adjustable oral appliance appears to be an effective mode of therapy to control OSA after an unsuccessful UPPP.     

典藏中国智慧 从《孔子》走向影坛的李欣汝

1月,备受关注的年度大戏《孔子》将亮相荧屏。在其中饰演霓裳的李欣汝,一个从古典舞中走出的女子,形神兼具的身韵翩然跳出最优美的舞姿,带你进入千年以前,那个烽火连天却笙箫依旧的春秋战国,领略中华名族的根髓。     

Dynamic complexes of beta2-adrenergic receptors with protein kinases and phosphatases and the role of gravin

Signals mediated by G-protein-linked receptors display agonist-induced attenuation and recovery involving both protein kinases and phosphatases. The role of protein kinases and phosphatases in agonist-induced attenuation and recovery of beta-adrenergic receptors was explored by two complementary approaches, antisense RNA suppression and co-immunoprecipitation of target elements. Protein phosphatases 2A and 2B are associated with the unstimulated receptor, the latter displaying a transient decrease followed by a 2-fold increase in the levels of association at 30 min following challenge with agonist. Protein kinase A displays a robust, agonist-induced association with beta-adrenergic receptors over the same period. Suppression of phosphatases 2A and 2B with antisense RNA or inhibition of their activity with calyculin A and FK506, respectively, blocks resensitization following agonist removal. Recycling of receptors to the plasma membrane following agonist-promoted sequestration is severely impaired by loss of either phosphatase 2B or protein kinase C. In addition, loss of protein kinase C diminishes association of phosphatase 2B with beta-adrenergic receptors. Overlay assays performed with the RII subunit of protein kinase A and co-immunoprecipitations reveal proteins of the A kinase-anchoring proteins (AKAP) family, including AKAP250 also known as gravin, associated with the beta-adrenergic receptor. Suppression of gravin expression disrupts recovery from agonist-induced desensitization, confirming the role of gravin in organization of G-protein-linked signaling complexes. The Ht31 peptide, which blocks AKAP protein-protein interactions, blocks association of beta-adrenergic receptors with protein kinase A. These data are the first to reveal dynamic complexes of beta-adrenergic receptors with protein kinases and phosphatases acting via an anchoring protein, gravin.     

Smoking and Parkinson''s disease: a dose-response relationship

BACKGROUND: Previous studies questioned the link between early childhood anemia and detrimental child development. OBJECTIVE: A population-based study was conducted to examine the association between early childhood anemia and mild or moderate metal retardation at 10 y of age. DESIGN: The present study linked early childhood nutrition data collected by the Special Supplemental Program for Women, Infants, and Children (WIC) and school records. Hemoglobin values were used to determine the relation between anemia in early life and children's placement in special education classes for mild or moderate mental retardation. Subjects were all participants in the WIC program. A computer program was used to link data from birth, WIC, and school records. RESULTS: Logistic regression showed an increased likelihood of mild or moderate mental retardation associated with anemia, independent of birth weight, maternal education, sex, race-ethnicity, the mother's age, or the child's age at entry into the WIC program. CONCLUSION: These findings support the proposition that efforts to prevent mild and moderate mental retardation should include providing children with adequate nutrition during early childhood.