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PubMed2005

Assessment of risk factors for second hip fractures in Japanese elderly.

In an attempt to identify a cohort with a high risk of suffering a fracture of the contralateral hip (second hip fracture), we assessed patients who had suffered hip fracture. A total of 714 patients (130 men and 584 women) were prospectively followed to determine those who suffered a second hip fracture. Pathologic hip fractures and fractures that emerged from high-energy trauma were excluded from the analysis. Age, gender, Singh Index (SI), fracture type, cognitive impairment, and comorbid medical conditions were investigated as medical predictors. The 714 patients were observed for 1,579.5 person-years (mean: 2.4+/-1.4 years per patient). During the observation period, 45 second hip fractures were identified (bilateral group), giving an overall incidence of 0.029 per person-year. The annual incidence rate declined linearly from the occasion of the initial fracture. Furthermore, the second hip fracture tended to occur increasingly within 8 months after the initial hip fracture. The second hip fracture was of the same type (trochanteric or cervical) in 79% of the trochanteric and 71% of the cervical fractures. There was no significant difference in the incidence of second hip fracture by gender or age. In addition, there was no significant difference in the distribution of SI grades of the unfractured hip at the initial hip fracture between the 669 patients who had not suffered a second hip fracture (unilateral group) and the bilateral group. Cox proportional hazard regression analysis revealed that increased risk of a second hip fracture was associated with senile dementia and Parkinson's disease. We concluded that careful follow-up of hip fracture patients associated with senile dementia and Parkinson's disease might effectively prevent the incidence of a second hip fracture.

Aged↗
PubMed1992

The S locus of flowering plants: when self-rejection is self-interest.

In certain families of flowering plants, a self-incompatibility (SI) locus prevents self-fertilization, by a specific interaction between the S-gene product produced in the pistil and the S-gene products borne on or expressed by the male gametophyte, the pollen grain. The female S-locus gene products for two families showing different types of SI have been putatively identified as major pistil glycoproteins (the S-locus-specific glycoproteins of the Brassicaceae and the S-RNases of the Solanaceae). However, they are distinct in sequence and mode of action. The nature of the S-locus gene product borne by the pollen is still uncertain in both systems.

Brassica↗
PubMed2003

Ce10Cl4Ga5 and Ln3ClGa4 (Ln = La, Ce): reduced halides or oxidized intermetallics?

The compounds Ce(10)Cl(4)Ga(5) and Ln(3)ClGa(4) (Ln = La, Ce) were synthesized from stoichiometric mixtures of Ln, LnCl(3), and Ga under Ar atmosphere in sealed Ta ampules at 910-1020 degrees C for 25-26 days. Ce(10)Cl(4)Ga(5) is isostructural to La(10)Cl(4)Ga(5) (space group I4/mcm, No. 140) with lattice constants a = 7.9546(11) A, c = 31.793(6) A. Ln(3)ClGa(4) represents a new structural type, also in the space group I4/mcm, with a = 8.1955(8) and 8.1123(11) A, c = 11.363(2) and 11.229(2) A, respectively, for Ln = La and Ce. Ce(10)Cl(4)Ga(5) features building blocks of Ga-centered Ce(6) trigonal prisms and distinctive two-dimensional intermetallic CuAl(2) and U(3)Si(2) type nets. Its electronic structure falls within the realm of reduced rare-earth halides. Ln(3)ClGa(4) also contains the intermetallic CuAl(2) type nets, but the interstitials are inverted: The building blocks are Cl-centered Ln(6) octahedra. Its electronic structure is characterized by strong peripheral Ln-Ga bonding stabilizing the Ln(6)Cl octahedron which normally would have its Ln-Ln antibonding orbitals filled with electrons from interstitials beyond chalcogen. Magnetic susceptibility and conductivity measurements confirm the metallic nature of all three compounds.

Journal Article↗
PubMed1983

Behavioral and content components of the structured interview assessment of the Type A behavior pattern in women.

The purpose of this study was to analyze relationships among (1) the global assessment of the Type A behavior pattern determined by the Structured Interview (SI), (2) the Type A score of the Jenkins Activity Survey (JAS), and (3) ratings of individual behaviors and content items in the SI. These relationships were analyzed in a sample of 88 white suburban women. The individual behaviors rated were four speech characteristics and motor pace. The correlation between SI global assessment of behavior pattern and JAS Type A score was only 0.27. SI global assessment was strongly correlated with ratings of individual behaviors such as speech speed, speech emphasis, and rapid motor pace. There was little or no correlation between these behaviors and the JAS Type A scores. For items reflecting the content of the interview responses, correlations with JAS Type A scores were generally stronger than correlations with SI global assessment. The findings for this sample of women are quite similar to results from previous studies of men. Thus, the characteristics that influence SI global assessment appear to be similar for women and men.

Adult↗
PubMed1985

The inhibited power motive, type A behavior, and patterns of cardiovascular response during the structured interview and Thematic Apperception Test.

The Type A behavior pattern and the inhibited power motive have been implicated in the development of coronary heart disease (CHD). Since it is widely believed that enhanced cardiovascular responsivity may be one mechanism by which individuals develop CHD, the present study examined the relationship of Type A behavior and the inhibited power motive to different patterns of cardiovascular response during two behavioral tasks. Forty-one (24 Type A's, 17 Type B's) male undergraduates underwent the Type A structured interview (SI) and the Thematic Apperception Test (TAT) while a broad range of cardiovascular functions were simultaneously recorded. Different patterns of cardiovascular response were observed during the SI and TAT, and Type A's showed a greater tendency than Type B's to exhibit increased heart rate (HR), systolic blood pressure (SBP), and forearm blood flow (FBF) during the SI and the preparatory phase (but not the story-telling phase) of the TAT. The inhibited power motive was not related to enhanced cardiovascular responsivity during the SI or TAT. The implications of these findings for the development of CHD are discussed.

Adult↗
PubMed1988

A note on measurement issues in type A research: let's not throw out the baby with the bath water.

It has been suggested that researchers rely exclusively on the structured interview (SI) to assess Type A behavior instead of using objective self-report measures, because the SI is the only prospectively validated instrument currently available. This article considers the costs and benefits of relying solely on the SI to measure Type A behavior. Although using only the SI would assure that researchers measure, in a relatively unobtrusive fashion, actual Type A behaviors known to be predictive of heart disease, it would dramatically increase research costs, impede longitudinal studies of changes in Type A behavior, reduce the validity of statistical conclusions, restrict the convergent and discriminant validity of the Type A construct, and ultimately inhibit our ability to improve accuracy in predicting heart disease. A set of recommendations is proposed for improving the quality of measurement in Type A research.

Humans↗
PubMed2006

Control of the stability, electron-transfer kinetics, and pH-dependent energetics of Si/H2O interfaces through methyl termination of Si(111) surfaces.

Methyl-terminated, n-type, (111)-oriented Si surfaces were prepared via a two-step chlorination-alkylation method. This surface modification passivated the Si surface toward electrochemical oxidation and thereby allowed measurements of interfacial electron-transfer processes in contact with aqueous solutions. The resulting semiconductor/liquid junctions exhibited interfacial kinetics behavior in accord with the ideal model of a semiconductor/liquid junction. In contrast to the behavior of H-terminated Si(111) surfaces, current density vs. potential measurements of CH(3)-terminated Si(111) surfaces in contact with an electron acceptor having a pH-independent redox potential (methyl viologen(2+/+)) were used to verify that the band edges of the modified Si electrode were fixed with respect to changes in solution pH. The results provide strong evidence that the energetics of chemically modified Si interfaces can be fixed with respect to pH and show that the band-edge energies of Si can be tuned independently of pH-derived variations in the electrochemical potential of the solution redox species.

Letter↗
PubMed2002

p(2x2) phase of buckled dimers of Si(100) observed on n-type substrates below 40 K by scanning tunneling microscopy.

We have investigated the basic surface reconstruction of Si(100) on well defined surfaces fabricated on various substrates at low temperatures (-80 K) by scanning tunneling microscopy. Below 40 K, the single p(2x2) phase, a phase never observed before, was observed exclusively on n-type substrates doped in the range of 0.002 to 0.017 Omega cm. We also exclude the possibility of the (2x1) symmetric dimer commonly observed at low temperature (-10 K) being the basic surface reconstruction by showing that a buckled dimer can be flip-flopped by the tunneling tip.

Journal Article↗
PubMed1986

Type A behavior, family history of hypertension, and cardiovascular responsivity among black women.

The purpose of this study was to determine the effects of Type A behavior and family history of hypertension on cardiovascular reactivity to mental stress in a group of employed black women. Measures of heart rate and of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were taken at rest, during a mental arithmetic task, and during the Type A Structured Interview (SI). Results indicated that the Type A behavior pattern was associated with SBP and DBP hyperresponsivity during the SI but not during mental arithmetic. Additionally, certain speech components of the Type A pattern, as well as features of the potential-for-hostility component, were also related to cardiovascular responses during the SI. Family history of hypertension did not influence the cardiovascular parameters either alone or in combination with Type A behavior. The results suggest that many of the cardiovascular response characteristics of the Type A pattern that have been observed in predominantly white samples also hold true for blacks. Replication of these findings with other subgroups of blacks, such as young females and middle-aged males, will help document the generality of these findings within the black population.

Adult↗
PubMed2002

Reactions of silicon atoms with methane and silane in solid argon: a matrix-spectroscopic study.

The reaction of silicon atoms with methane (1) and silane (7) in argon at 10 K has been studied. Methane (1) is found to be inert to silicon atoms, but reaction occurs upon photochemical excitation under formation of methylsilylene (2). On the contrary, silane (7) is spontaneously converted into a mixture of silylsilylene (10) and disilene (12). Subsequent irradiation generates the butterfly-type disilyne Si(2)H(2) (14), together with a third photoproduct, which we assume to be the doubly bridged Si(2)H(4) isomer 13. The structural elucidation of the new species is based on the comparison of the experimental IR and UV/Vis spectra with data from density functional theory calculations. The results are supported by isotopic labeling studies.

Journal Article↗
PubMed2006

A close look at short C-CH3...potassium contacts: synthetic and theoretical investigations of [M2Co2(mu3-OtBu)2(mu2-OtBu)4(thf)n] (M = Na, K, Rb, thf = tetrahydrofuran).

Agostic interactions of the type Si-CH3M+ (M = alkali metal) are frequently mentioned in discussions of solid-state structures of trimethylsilyl compounds and the purpose of this work was to elucidate if they also exist in the related tert-butyl species by using density functional theory. The compounds [M2Co2(mu3-OtBu)2(mu2-OtBu)4(thf)n] (M = Na, n = 2; M = K, n = 0; M = Rb, n = 1) have been synthesised and their crystal structures determined. Close contacts of methyl groups with K atoms are observed in the solid-state structure of [K2Co2(mu3-OtBu)2(mu2-OtBu)4], and calculations of the rotational barrier of a tert-butoxy group about the axis through the C-O bond were performed. It was shown that apparent short C-CH3K distances are in this case a consequence of the packing in the extended solid-state structure.

Journal Article↗
PubMed2007

Water-soluble carbosilane dendrimers: synthesis biocompatibility and complexation with oligonucleotides; evaluation for medical applications.

Novel amine- or ammonium-terminated carbosilane dendrimers of type nG-[Si{OCH2(C6H3)-3,5-(OCH2CH2NMe2)2}]x, nG-[Si{O(CH2)2N(Me)(CH2)2NMe2}]x and nG-[Si{(CH2)3NH2}]x or nG-[Si{OCH2(C6H3)-3,5-(OCH2CH2NMe3 +I-)2}]x, nG-[Si{O(CH2)2N(Me)(CH2)2NMe3 +I-}]x, and nG-[Si{(CH2)3NH3 +Cl-}]x have been synthesized and characterized up to the third generation by two strategies: 1) alcoholysis of Si--Cl bonds with amino alcohols and subsequent quaternization with MeI, and 2) hydrosilylation of allylamine with Si--H bonds of the dendritic systems and subsequent quaternization with HCl. Quaternized carbosilane dendrimers are soluble in water, although degradation is apparent due to hydrolysis of Si--O bonds. However, dendrimers containing Si--C bonds are water-stable. The biocompatibility of the second-generation dendrimers in primary cell cultures of peripheral blood mononuclear cells (PBMCs) and erythrocytes have been analyzed, and they show good toxicity profiles over extended periods. In addition, we describe a study on the interactions between the different carbosilane dendrimers and DNA oligodeoxynucleotides (ODNs) and plasmids along with a comparative analysis of their toxicity. They can form complexes with DNA ODNs and plasmids at biocompatible doses via electrostatic interaction. Also a preliminary transfection assay has been accomplished. These results demonstrate that the new ammonium-terminated carbosilane dendrimers are good base molecules to be considered for biomedical applications.

Cell Survival↗
PubMedDate not supplied

Possible effect of angiotensin-converting enzyme inhibition on glomerular charge selectivity.

Angiotensin-converting enzyme (ACE) inhibitors are known to reduce urinary albumin excretion (UAE) in diabetic patients. Animal studies have shown that, besides diminishing the glomerular capillary pressure, ACE inhibitors might reduce albuminuria by influencing glomerular charge selectivity through glomerular preservation of heparan sulphate proteoglycan. In humans, an indirect measurement of glomerular charge selectivity can be obtained by calculating the glomerular charge selectivity index (SI), a clearance ratio of IgG/IgG4, two identically sized but differently charged molecules. The aim of the present study was to evaluate the effect of ACE inhibition on charge selectivity by comparing SI in type I (insulin-dependent) diabetic patients with microalbuminuria after 6 years of treatment either with or without captopril. Thirty-five of 45 patients participating in a prospective randomized study evaluating the effect of captopril in preventing the development of diabetic nephropathy were included in the present study, 17 being treated with captopril, 18 left as untreated controls. The selectivity index was calculated after measuring s-IgG, u-IgG, s-IgG4, and u-IgG4. The results demonstrated a higher selectivity index in the captopril-treated group [1.21 (0.51-1.94) median (range)] compared to the control group [0.94 (0.31-1.87)], however, the difference was not statistically significant (p = 0.16). A negative correlation between the selectivity index and UAE was demonstrated in the captopril-treated group (r = -0.77; p = 0.0004), whereas the correlation in the control group did not reach statistical significance (r = -0.3; p = 0.2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

SAW characteristics of AlN films sputtered on silicon substrates.

This article is focused on the analysis of the electroacoustic response of surface acoustic wave (SAW) filters made of aluminium nitride (AlN) thin films on various types of Si wafers. AlN films with (00.2) orientation were deposited by RF reactive sputtering of an Al target in Ar and N(2) admixtures on Si(100) and (111) wafers with resistivities ranging between 10 and 2000 Omega cm. The electroacoustic response of SAW filters with an acoustic wavelength of 40 microm was analysed by measuring the Sij parameters with a network analyser. We have determined that the out-of-band loss is directly related to the Si substrate resistivity, varying from 26 dB for 10 Omega cm to 55 dB for 2000 Omega cm. The SAW velocity depends on the orientation of the Si wafer, being approximately 4700 m/s for Si(111) and 5100 m/s for Si(100). The electroacoustic responses of the SAW filters were fitted by computations based on a simple circuital model that takes into account parasitic effects such as airborne electromagnetic coupling and conduction through the substrate. This procedure provides accurate values of the electromechanical coupling factor k2 even for devices with poor characteristics. Good quality SAW filters of AlN on high resistivity Si(100) wafers with k2 larger than 0.12% are demonstrated.

Journal Article↗
PubMed2001

Patient satisfaction after uneventful cataract surgery with implantation of a silicone or acrylic foldable intraocular lens. Comparative study.

PURPOSE: To compare patient satisfaction with vision 12 months after implantation of a silicone or acrylic foldable intraocular lens (IOL). SETTING: John A. Moran Eye Center, University of Utah Medical Center, Salt Lake City, Utah, USA. METHODS: Selection criteria included patients who had uneventful cataract extraction by phacoemulsification with a temporal clear corneal incision or superior scleral tunnel incision, a curvilinear capsulorhexis, and in-the-bag IOL placement. One hundred sixty-two patients surveyed had a mean follow-up of approximately 15 months (range 12 to 18 months). Patients were divided into 3 groups of 54 each based on IOL type: AMO SI-30/40, Alcon MA30BA, and Alcon MA60BA. All patients were surveyed over the telephone using a standardized questionnaire protocol. They were questioned about their perception of vision with best optical correction in relation to visual blurring symptoms, glare symptoms, night vision, near vision, and overall vision. RESULTS: There were no significant differences in patient satisfaction among the 3 IOL groups in visual blurring or night vision. Patients in the SI-30/40 and MA60BA groups reported significantly higher satisfaction with glare symptoms, near vision, and overall satisfaction than patients in the MA30BA group. CONCLUSION: The SI-30/SI-40 and the MA60BA IOLs received significantly higher patient satisfaction scores than the MA30BA IOL in glare symptoms, near vision, and overall satisfaction.

Acrylic Resins↗
PubMed1997

Characterization of Spanish sepiolites by high-resolution solid-state NMR.

29Si NMR (MAS and CP/MAS) and 1H MAS NMR techniques were used to characterize four sepiolites, two of natural origin (commercialized under the names Pangel and Pansil) and the other two obtained from them by treatment with 2 M or 4 M H2SO4, respectively. These techniques were used to identify the structural and surface changes undergone by sepiolites by the effects of acid treatment and calcination. Various types of Si were detected; also, treatment with 4 M H2SO4 destroyed the sepiolite and produced fibrous silica.

Isotopes↗
PubMed2002

Intramolecular charge-transfer process of jet-cooled (p-cyanophenyl)pentamethyldisilane: roles of the torsional motion and the Si-Si bond change.

To investigate the intramolecular charge-transfer (ICT) process of (p-cyanophenyl)pentamethyldisilane (CPDS), laser-induced fluorescence, dispersed fluorescence, and two-color resonance enhanced two-photon ionization spectra were measured in a jet-cooled isolated condition. Dual fluorescence of CPDS was observed from a ground vibrational level in the locally excited pipi state. Similar to an emission from the charge-transfer (CT) state in solution, one of the dual emissions of the isolated molecule in the jet was assigned as the CT emission. A significant vibrational dependence on the ICT process was found as exciting vibronic levels of the molecule. It was identified that the promoting mode of the ICT process is a torsional motion of the disilanyl group with respect to the phenyl ring. It was also revealed that an effective appearance energy of the CPDS cation via the CT state is much lower than that via the locally excited pipi state suggesting that the electronic configuration of the CT state is similar to that of the cation. On the basis of an electronic configuration of the cationic state, that of the CT state was suggested to be of the (sigma(Si)(-)(Si), 2ppi) type.

Journal Article↗
PubMed2003

A stable silicon-based allene analogue with a formally sp-hybridized silicon atom.

Carbon chemistry exhibits a rich variety in bonding patterns, with homo- or heteronuclear multiple bonds involving sp-hybridized carbon atoms as found in molecules such as acetylenes, nitriles, allenes and carbon dioxide. Carbon's heavier homologues in group 14 of the periodic table--including silicon, germanium and tin--were long thought incapable of forming multiple bonds because of the less effective p(pi)-p(pi) orbital overlap involved in the multiple bonds. However, bulky substituents can protect unsaturated bonds and stabilize compounds with formally sp-hybridized heavy group-14 atoms: stable germanium, tin and lead analogues of acetylene derivatives and a marginally stable tristannaallene have now been reported. However, no stable silicon compounds with formal sp-silicon atoms have been isolated. Evidence for the existence of a persistent disilaacetylene and trapping of transient 2-silaallenes and other X = Si = X' type compounds (X, X' = O, CR2, NR, and so on) are also known, but stable silicon compounds with formally sp-hybridized silicon atoms have not yet been isolated. Here we report the synthesis of a thermally stable, crystalline trisilaallene derivative containing a formally sp-hybridized silicon atom. We find that, in contrast to linear carbon allenes, the trisilaallene is significantly bent. The central silicon in the molecule is dynamically disordered, which we ascribe to ready rotation of the central silicon atom around the molecular axis.

Journal Article↗