Disorder-related risk factors for revision total hip arthroplasty after hip hemiarthroplasty in displaced femoral neck fracture patients: a nationwide population-based cohort study

Background

The choice of primary hip hemiarthroplasty or total hip arthroplasty for displaced femoral neck fracture is still controversial. Revision hip arthroplasty not only increases risk and cost but also could result in worse outcome. Determining the risk factors for revision can help inform medical decision-making and aid in risk stratification of publicly reported outcomes. Therefore, we conducted a nationwide population-based study to identify the disease-related risk factors and construct a risk score nomogram to predict revision surgery.

Methods

Records of all 68,030 femoral neck fracture patients receiving partial hemiarthroplasty (HA) in 2000–2010, with no total hip arthroplasty (THA) or revision HA history, were collected from the National Health Insurance Research Database. Cox proportional hazard regression was used to estimate the risk of revision hip replacement (RHA). The score of each risk factor was the quotient of the regression coefficient of the variable by the regression coefficient for a 10-year increase in age. The predictive accuracy was tested using the area under the receiver operating characteristic curve (AUROC).

Results

The revision risk for hemiarthroplasty increased in male, those with schizophrenia and end-stage renal disease patients had 1.58-, 1.88-, and 1.74-fold revision HA risk (95 % confidence interval (CI) = 1.40–1.78, 1.26–2.79, and 1.29–2.34, respectively). In a predictive model, the cumulative risk score ranged from 0 to 13 with a 5.08 to 91.82 % 10-year predicted RHA risk. The percentage of AUROC for 10-year RHA risk in nomogram was 61.9 (95 % CI = 60.0–63.4).

Conclusions

Males, schizophrenia and end-stage renal disease patients have higher risk of revision surgery after hemiarthroplasty for femoral neck fracture.

Parasite-induced processes for adenosine permeation in mouse erythrocytes infected with the malarial parasite Plasmodium yoelii

In mouse erythrocytes harbouring the malarial parasite Plasmodium yoelii, three processes contributed to inward fluxes of adenosine, one of which is attributed to the native nucleoside transporter, because of the inhibitory effects of nitrobenzylthioinosine (NBMPR). New (parasite-induced) permeation processes of low NBMPR-sensitivity were (i) saturable fluxes with preference for the D enantiomer (D-Ado) and (ii) apparently unsaturable fluxes that proceeded by a channel-like route without enantiomeric selectivity. Parasite-induced fluxes of L- and D-Ado were similarly inhibited by furosemide [IC50 (concn. causing half-maximal inhibition) 15-17 microM], whereas D-Ado fluxes in uninfected erythrocytes were 10-fold less sensitive.

Factors influencing the heat shock response of Xenopus laevis embryos

We have further characterized the heat shock response of Xenopus laevis embryos. Xenopus embryos respond to heat shock by consistently synthesizing four major heat shock proteins (hsps) of 62, 70, 76, and 87 kilodaltons. In addition to these hsps, heat-shocked embryos also exhibit the synthesis of several minor hsps. The synthesis of these hsps is often variable. We have monitored the effects of different temperatures and lengths of heat shock on the pattern and intensity of hsp synthesis. In general, the four major hsps are induced more strongly at higher temperatures and during increasing intervals of heat shock. The temperature and duration of heat shock can affect the synthesis of the minor hsps, however. Some hsps are synthesized at lower temperatures only (i.e., below 37 degrees C), whereas others are synthesized only at higher temperatures (i.e., above 37 degrees C). We have extensively examined the characteristics of hsp 35 synthesis, one of the most variably synthesized hsps. This hsp is characteristically synthesized at temperatures above 35 degrees C and usually during the first 40 min of heat shock, after which it becomes undetectable. In some experiments, its synthesis is restimulated during later intervals of heat shock. Hsp 35 is also under developmental regulation. It is not synthesized by heat-shocked embryos until the late blastula to early gastrula stage. After this brief period of inducibility, its synthesis is dramatically reduced in mid- to late gastrulae, but reappears in heat-shocked neurulae. We have previously demonstrated that hsp 35 is related to the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The induction of hsp 35 synthesis is inversely correlated with the constitutive levels of GAPDH specific activity. In this paper we document further correlations between the synthesis of hsp 35 and GAPDH specific activity during early Xenopus development.

Concentration-dependent enhancement of 1-dodecylazacycloheptan-2-one on the percutaneous penetration kinetics of triamcinolone acetonide

The enhancing effect of 1-dodecylazacycloheptan-2-one (I) on the penetration kinetics of triamcinolone acetonide (II) and the possible mechanisms of enhancement were studied using nonreinforced and reinforced silicone elastomer membranes and full-thickness hairless mouse skin as penetration barriers. Lactam I, at test concentrations of 0.1-10%, significantly promoted the extent and the rate of penetration of the acetonide II. Regardless of the barrier used the effect was concentration dependent, but the penetration profiles were different. The enhancement with synthetic membranes was attributed solely to the effect of lactam I doubling the diffusion constant (D), which resulted in the increase of the permeability coefficient (Kp) and the shortening of the lag time (tau); the partition coefficient (Km), however, was not affected. With mouse skin, I exerted effects on both D and Km. Compound I potentiated the retention of II in skin (a reservoir effect) about sevenfold; however, the enhancing reservoir effect was independent of the concentration of I. Pretreatment with I was found to be more efficient than the coapplication of I and II in the vehicle. The coexistence of I and II was not required for the enhancement, and the reduced enhancing efficiency suggested an interaction between I and II in the vehicle. Penetration impedance was observed after exposure to I with skin, but not with synthetic membranes. Interaction of I with the skin component, or the coexistence of I and II in the skin, could be responsible for such an impedance.

A prostaglandin-adrenergic link occurs in the hypothalamic pathways which mediate the fever induced by vasopressin in the rat

The effects of direct administration of vasopressin into the preoptic anterior hypothalamus on thermoregulatory functions were assessed in conscious rats at various ambient temperatures. Intrahypothalamic administration of vasopressin caused fever, increased metabolic heat production and decreased heat loss (cutaneous vasoconstriction) in rats. There was no changes in respiratory evaporative heat loss in response to administration of these drugs. Furthermore, it was found that the fever reactions induced by intrahypothalamic vasopressin was antagonized by pretreatment of animals with an intrahypothalamic dose of either yohimbine (an alpha-adrenergic receptor antagonist), propranolol (a beta-adrenergic receptor antagonist), or sodium acetylsalicylate (a prostaglandin synthetase inhibitor). The data indicate that a prostaglandin-adrenergic link occurs in the hypothalamic pathways which mediate the vasopressin-induced fever in rats.

Wind measurements by the temporal cross-correlation of the optical scintillations

Various methods of correlation analysis that have been used to deduce crosswind from a drifting scintillation pattern are briefly described and then compared with regard to their immunity to noise and their accuracy when faced with nonuniformities along the propagation path or changes in the characteristics of the turbulence. Of the techniques considered, none is ideal; but a new technique, using complete knowledge of the cross-covariance function, proves to be advantageous in a wide variety of situations.

Simple inversion technique to obtain cloud droplet size parameters using solar aureole data

A simple inversion technique in the single scattering regime has been developed to deduce cloud droplet size parameters by using the measurement of the radiance of near-forward scattered solar radiation as a function of angle. Compared with the numerical inversion technique that uses exact Mie scattering calculations, the new technique is much less time-consuming and hence should be usable in an on-line real time analysis. To test the effectiveness of the new technique, we use the results of polydispersed cloud size distribution calculated by Deirmendjian to retrieve the model size parameters. The agreement is excellent. We also generalize the theory to include the broadband source. A typical experimental example is given. Its comparison with time-consuming Mie scattering inversion technique again shows excellent agreement.

Optical rain gauge using a divergent beam

We have shown that path-averaged rain rates can be obtained from the raindrop-induced amplitude scintillations of a divergent laser beam (spherical wave case). We found that the rain rate obtained from a divergent beam is less sensitive to drop-size distribution than that from a collimated beam. However, the path-weighting function is heavily weighted toward the receiving end in the spherical wave case, whereas in the plane wave case, it is almost uniformly weighted along the optical path. The theory was confirmed by observations on two optical paths, one using a collimated beam on a 200-m path, the other using a divergent beam on a 1000-m path. The results for the longer path show a saturation effect for rain rates higher than 12 mm/h.

Finite aperture optical scintillometer for profiling wind and C(2)(n)

A new optical technique is described for measuring the path profiles of crosswind and of a refractive-index structure parameter C(2)(n) along a line-of-sight path. Different sizes of transmitters and receivers are used to control the path-weighting function so that it will peak at different path locations. Various linear combinations of these measurements yield the path profile of crosswind and C(2)(n). A prototype instrument has been built and tested. Experimental results show good agreement with the theoretical predictions.

Simplified optical path-averaged rain gauge

It has previously been shown that the scintillations produced by raindrops falling through a collimated laser beam can be used to measure the drop-size distribution and the rainfall rate, both averaged over the path. We now present a theoretical analysis, verified by observation, showing that the variance of the scintillations detected by a line-detector measured at frequencies near 1 kHz is closely related to rain rate and is nearly independent of drop-size distribution. If only rain rate is desired, the variance type of optical rain gauge has several advantages over the earlier model. It could use a diverging beam, thus eliminating the practical difficulties of maintaining adjustment and pointing of a collimated beam. Furthermore, it is less sensitive to the presence of updrafts and downdrafts along the beam and can thus be used over rough terrain.

Measurement of rain parameters by optical scintillation: computer simulation of the correlation method

Earlier analysis of the use of laser-beam scintillations to measure path-averaged rainfall rate and drop-size distribution has been well verified for pathlengths up to 140 m even though, for such a path, overlapping of the scintillation patterns violates a simplifying assumption of the analyses. Analytic extension of the theory to the case where the scintillation patterns overlap appears intractable, so a computer simulation has been used to investigate that limitation of the theory. That simulation, presented here, verifies that the original scintillation-covariance technique for measuring rainfall parameters is, with only a slight modification, still applicable in the presence of overlapping scintillation patterns from many raindrops.

Measurement of rain parameters by optical scintillation

We describe a technique for measuring path-averaged rain parameters by analyzing the rainfall-induced scintillations of a laser beam. From the time-lagged covariance function of two vertically spaced line detectors, we determine the average rainfall rate and drop-size distribution along the optical path. This technique requires no prior assumption of the form of the drop-size distribution. Sample measurements on a 140-m path confirm that the path-averaged drop-size distribution of a steady rain follows a Marshall-Palmer distribution. The optically measured path-averaged rain rate also shows good agreement with conventional tipping-bucket rain-gauge data.

Refractive-turbulence profiles measured by one-dimensional spatial filtering of scintillations

Stellar scintillations, when appropriately analyzed, yield information about the turbulence throughout the atmosphere. We describe an instrument involving a 36-cm telescope and an on-line minicomputer that provides, after 20 min of observation, the refractive-turbulence profile of the atmosphere. The height resolution is sufficient to divide the atmosphere into about four independent regions. The principal limitation to greater accuracy and resolution is the nonstationary behavior of the atmosphere during the 20-min observing period.

Laser wind sensing: the effects of saturation of scintillation

We have developed a physically based extension of the first-order perturbation theory of optical scintillation that accounts for the observed variance and covariance of the amplitude fluctuations in strong integrated turbulence. We use this model to analyze the experimentally observed changes in the operation of our laser wind sensor. The theory suggests a transmitter-receiver configuration that can nearly eliminate the performance-degrading effects of strong turbulence. Based on this analysis, we have developed a saturation-resistant optical wind sensor that maintains its calibration and wind-weighting function throughout the observed range of integrated-turbulence values.

Optical wind sensing by observing the scintillations of a random scene

We demonstrate the feasibility of using a naturally illuminated scene, such as a hillside or forest, as a passive optical source to measure the path-averaged crosswind between the scene and the observer. The resultant path weighting function for the crosswind cannot be varied arbitrarily, but we can obtain a useful range of weighting functions by adjusting the geometry of the receiver.

Wind and refractive-turbulence sensing using crossed laser beams

The theory of optical propagation through atmospheric turbulence demonstrates the sensitivity of such quantities as log-amplitude variance and covariance to strength of refractive turbulence and transverse wind. We exploit this sensitivity by using a crossed-path technique to derive path profiles of these quantities. The results are insensitive to changes in the spatial spectrum of the refractive-index variations. The path resolution is easily varied by changing the receiver and transmitter separations and is ultimately limited by signal-to-noise considerations. The experimental results for horizontal paths, described here, will ultimately be used to indicate the feasibility of profiling on vertical paths with passive sources.