Current concepts in dentin bonding: focusing on dentinal adhesion factors

With greater need for treating root surface lesions, dentinal adhesives are more in demand. For successful treatment, all factors--dentin, tooth, patient and materials--must be considered.     

Characterization of the bioactive form and molecular determinants of recognition of cyclic enkephalin peptides at the delta-opioid receptor

An extensive and systematic search strategy to determine the conformational profile of 12 cyclic disulfide-bridged opioid peptides with varying affinities at the delta receptor has been carried out to identify the structure that is recognized by the delta receptor for each analogue. The methods and procedures used here for the conformational search have already been validated for [D-Pen2,D-Pen5] enkephalin (DPDPE), one member of this family. Use of these methods led to a low-energy solution conformation of DPDPE in excellent agreement with all the geometric properties deduced from its solution nmr spectra. Each of the analogue was subjected to the same procedure, involving a combination of molecular dynamics simulations at high and low temperature. The study was repeated in two environmental conditions, an apolar environment, simulated by using a distance-dependent dielectric constant, and a polar environment by embedding the peptides in a high constant dielectric (epsilon = 80). An automated comparison of the different conformers based on their backbone rms and average distance between the key aromatic moieties was followed by graphic analysis using maximum structural overlap. The cross-comparison of the conformations for each analogue revealed a unique conformer that may be recognized by the delta receptor for each high-affinity analogue that permitted maintaining the critical elements required for recognition in a simple spatial orientation, while maximizing similarity in other regions.     

Hormone replacement therapy and the risk of stroke. Follow-up of a population-based cohort in Sweden

BACKGROUND: The protective effect of postmenopausal estrogen replacement therapy on coronary heart disease has been shown in several studies. However, the effect on stroke is more controversial, and data on estrogen-progestin combinations are sparse. METHODS: A total of 23,088 women living in the Uppsala (Sweden) Health Care Region were identified from pharmacy records as having been prescribed noncontraceptive estrogens during 1977 through 1980. They were followed up from 1977 to 1983 for admissions to the hospital because of a first stroke (International Classification of Diseases, Eighth Revision, codes 430 through 438 and 344). The mean observation time was 5.8 years. The expected number was based on person-years in the cohort and incidence rates in the population of the region. RESULTS: Overall, 361 cases of first stroke were observed in the cohort, as compared with 403.2 expected (relative risk [RR], 0.90; 95% confidence limits, 0.81, 0.99). The RR for acute stroke (International Classification of Diseases, Eighth Revision, codes 431 through 436) was 0.85 (0.75, 0.97). In women younger than 60 years at entry who were prescribed estradiol compounds (1 to 2 mg) or conjugated equine estrogens (0.625 to 1.25 mg), the risk of any stroke was reduced by almost 30% (RR, 0.72; 0.58, 0.88) and the risk of acute stroke was reduced by 40% (RR, 0.61; 0.46, 0.79). Women prescribed a combined estradiol-levonorgestrel brand also had a lowered risk of stroke (RR, 0.61; 0.40, 0.88). Weak compounds (mainly estriol) showed no stroke-protective effect, nor was there any relationship between hormone replacement and risk of subarachnoid hemorrhage. CONCLUSION: Hormone replacement therapy with potent estrogens alone or cyclically combined with progestins can, particularly when started shortly after menopause, reduce the risk of stroke.     

量度及預測隧道鑽機的土傳噪音及震動

在市區進行夜間隧道鑽挖工程所產生的土傳噪音及震動,容易引起投訴。現時的技術難以準確預測噪音及震動的級數,而隧道工程的進度也常因進行隧道鑽挖工程時產生過大的土傳噪音及震動而延誤。本文所提述的新技術,可以更準確地量度及預測鑽機震動強度及土壤傳震的特性@個技術包括測量單位衝擊力及隧道鑽機摩擦力所產生的震動級數鋵嵲珈?80於代,美國政府運輸部門(U.S.DeptofTransportationFederalTransitAdministrative)已研發相關的技術,並將該技術應用於鐵路土傳噪音量度及預測上。本文報告隧道鑽機所產生的土傳噪音及震動級數1/3倍頻帶數值的量度及預測。比較地面震動峰值速度(PPV)、最高(Lmax)噪聲和振動級數按快速和緩慢的時間常數和整體百分比(Percentile)數值列出。     

Viscoelastic response of solid rocket motor components for service life assessment

A methodology for determining the response of rocket motor materials and bondlines to thermal loadings by measuring their dynamic mechanical properties is reported. The critical temperatures at which debonding and/or propellant cracking occur and the number of thermal cycles required to induce failure were evaluated. These results were compared with those from instrumented rocket motors subjected to similar thermal loadings. A model, developed for fibre reinforced composites, was applied to the propellant-inhibitor bimaterial obtained from a rocket motor. The internal energy dissipation due to a lack of perfect adhesion at the propellant–inhibitor interface, tan δ_adh, was used to give an indication of the failure mode of the bondline (i.e., adhesive failure at the interface or cohesive failure in the propellant) and the bond adhesion parameter, C, was related to the bond strength measured by rectangular bond-in-tension tests. This revised version was published online in November 2006 with corrections to the Cover Date.     

Selective cytotoxicity of two rodent T cell lymphomas to rat yolk sac tumours involves a retroviral envelope protein expressed by the lymphoma

OBJECTIVE: To test a model for the study of inequalities in hospitalizations in the city of Ribeirao Preto (SP), understanding them to be due both to the social position of inpatients and also to health care policies in Brazil. MATERIAL AND METHOD: Using a hospital information system in existence for more than 25 years in the city of Ribeirao Preto-SP, 56.293 hospitalizations of municipal inhabitants occurring in some of the 12 general hospitals in 1993, were studied. Using the Brazilian occupancy classification for mortality, these inpatients were grouped on 6 occupational levels, as in the British classification: professional, intermediate, qualified non manual, qualified manual, partially qualified and unqualified. RESULTS AND CONCLUSIONS: Two-thirds of the inpatients had no place in the i.e. did not belong to the economically active population--and consisted of housewives, pensioners, children and students--and one third had some economic activity and thus belonged to the economically the active population. A close association was found between social strata and the classification of the hospital financing system into private, private group clinic and public health system patients. There were differences in hospital parameters as well as in morbidity patterns between these groups. The inequalities relating to average age, average age of hospital deaths, mean lengths of stay, hospital mortality, re-internment and frequency of diseases are discussed. This model allows the social position of the inpatient to be estimated using the hospital financing system, including also those patients with no economic activity, which covers the majority of the population. Social mechanisms created to compensate for inequalities in the welfare state do not cancel out the social differences.     

Birthdate and cell marker analysis of scrambler: a novel mutation affecting cortical development with a reeler-like phenotype

The reeler mutation in mice produces an especially well characterized disorder, with systematically abnormal migration of cerebral cortical neurons. The reeler gene encodes a large protein, termed Reelin, that in the cortex is synthesized and secreted exclusively in the Cajal-Retzius neurons of the cortical marginal zone (D'Arcangelo et al., 1995). In reeler mutant mice, loss of Reelin protein is associated with a systematic loss of the normal, "inside-out" sequence of neurogenesis in the cortex: neurons are formed in the normal sequence but become localized in the cortex in a somewhat inverted, although relatively disorganized "outside-in" pattern. Here we show that the scrambler mutant mouse exhibits a loss of lamination in the cortex and hippocampus that is indistinguishable from that seen in the reeler mouse. We use BrdU birthdating studies to show that scrambler cortex shows a somewhat inverted "outside-in" sequence of birthdates for cortical neurons that is similar to that previously described in reeler cortex. Finally, we perform staining with the CR-50 monoclonal antibody (Ogawa et al., 1995), which recognizes the Reelin protein (D'Arcangelo et al., 1997). We show that Reelin immunoreactivity is present in the scrambler cortex in a normal pattern, suggesting that Reelin is synthesized and released normally. Our data suggest that scrambler is a mutation in the same gene pathway as the reeler gene (Relnrl) and is most likely downstream of Relnrl.