Spontaneous diametric-drive acceleration initiated by a single beam in a photonic lattice

We demonstrate that a single Gaussian-like beam can self-bend during nonlinear propagation in a uniform photonic lattice. The two components of the beam experiencing normal and anomalous diffractions spontaneously separate and form a pair in a diametric-drive acceleration due to nonlinear action. Such a diametric drive generally describes a jointly accelerating behavior of two beams analogous to positive- and negative-mass objects. The influences of the initial momentum of the input beam and the nonlinear strength are considered in this process. We further realize a self-bending propagation for a partially coherent light beam and discuss the impact of incoherence on the acceleration strength.

Coherent propulsion with negative-mass fields in a photonic lattice

In this Letter, we demonstrate the first, to the best of our knowledge, coherent propulsion with negative-mass fields in an optical analog. We observe a self-accelerating state, driven by a nonlinear coherent interaction of its two components that are experiencing diffractions of opposite signs in a photonic lattice, which is analogous to the interaction of two objects with opposite mass signs. Surprisingly, the coherent propulsion is highly immune to the initial phase of the two components, which is in sharp contrast with the behavior encountered in traditional coherent wave interactions. Compared to its incoherent counter-part, the coherent propulsion exhibits an enhanced acceleration.

Oromandibular reconstruction using microvascularized bone flap: report of 1038 cases from a single institution

This retrospective study was performed to review 1038 patients who underwent mandibular reconstruction with free vascularized bone flaps at a single institution between 2006 and 2017. Of these patients, 827 (79.67%) had fibula flaps, 197 (18.98%) had deep circumflex iliac artery perforator (DCIA) flaps, and 11 (1.06%) had scapula bone flaps. The most common pathological diagnosis was ameloblastoma (n=366, 35.26%), followed by squamous cell carcinoma (n=278, 26.78%) and osteoradionecrosis (n=152, 14.64%). Fifty-seven patients (5.49%) had major complications requiring surgical intervention and one patient died of a pulmonary embolism. Venous crisis was the most frequent major complication (n=20, 1.93%), followed by haematoma (n=17, 1.64%) and flap necrosis (n=14, 1.35%). One-stage mandibular reconstruction was preferred whenever possible, as this generally decreases the financial and hospitalization burden. The four-segment method of jaw reconstruction appeared to achieve good aesthetic appearance results in Asian patients and this was not associated with a higher risk of segment ischemia compared with the three-segment method.

Optical amplification of Airy beams by photorefractive two-wave mixing

We propose and demonstrate nonlinear amplifications of self-accelerating Airy beams by two-wave mixing in photorefractive crystals both numerically and experimentally. By employing a broad Gaussian beam as the pump beam, we show that weak signal Airy beams can be significantly amplified under both diffusion and drift mechanisms. It is revealed that not only higher optical gains but also faster response time can be achieved in the presence of an external electric field, where the drift mechanism dominates. We verify that the self-accelerating and self-healing characteristics of the Airy beams are well preserved during the nonlinear amplification.

Observation of spatial optical diametric drive acceleration in photonic lattices

We experimentally and theoretically demonstrate a spatial diametric drive acceleration of two mutually incoherent optical beams in 1D optical lattices under a self-defocusing nonlinearity. The two beams, exciting the modes at the top/bottom edges of the first Bloch band and hence experiencing normal/anomalous diffraction, can bind together and bend in the same direction during nonlinear propagation, analogous to the interplay between two objects with opposite signs of mass that breaks Newton's third law. Their spatial spectrum changes associated with the acceleration are analyzed for different lattice modulations. We find that the acceleration limit is determined by the beam exciting the top band edge that reaches a saturated momentum change prior to the other pairing beam.

MiR-128 regulation of glucose metabolism and cell proliferation in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is prone to metastasis and has a poor prognosis, with lower survival rates than other breast cancer subtypes. MicroRNAs have recently emerged as powerful regulators of cancer processes and become a promising target in cancer therapy.

METHODS

Expression of miR-128 was examined in invasive ductal breast cancer, and its relationship with clinicopathological features analysed. A series of in vitro and in vivo experiments were performed to investigate the function and mechanism of miR-128 in the development of invasive ductal breast cancer.

RESULTS

A cohort of 110 women with TNBC and 117 with non-TNBC were included in the study. In multivariable Cox regression analysis, overall and disease-free survival were significantly associated with lymph node metastasis, histological grade and molecular subtype. Subgroup analysis showed that low expression of miR-128 correlated with shorter overall and disease-free survival in TNBC (P < 0·001), and shorter overall but not disease-free survival in non-TNBC. In addition, miR-128 was able to inhibit glucose metabolism, mitochondrial respiration and proliferation of TNBC cells. These effects were consistent with miR-128 targeting inhibition of the insulin receptor and insulin receptor substrate 1.

CONCLUSION

MiR-128 might be a prognostic marker and possible molecular target for therapy in patients with TNBC.

Clinical efficacy of one stage posterior debridement joint graft fixation for lumbar vertebral fractures in spinal tuberculosis patients with compression

OBJECTIVE

Spinal tuberculosis, though destructive, can be cured in many patients by chemotherapy, though surgery is often necessary for decompression and deformity correction. Our aim of this study was to investigate the clinical efficacy of posterior debridement joint graft fixation therapy for lumbar vertebral fractures in patients with spinal tuberculosis with a compression fracture.

PATIENTS AND METHODS

We prospectively included 48 patients diagnosed with spinal tuberculosis and lumbar compression fracture in our hospital from June 2010 to June 2013. The patients were randomly divided into observation group (n = 27) and control group (n = 21). The patients in the control group underwent an anterior debridement joint bone fixation therapy, whereas, the patients in the observation group underwent one stage posterior debridement joint bone fixation therapy. The patients in the both groups were followed-up for about 2 years and the postoperative complications were recorded and analyzed.

RESULTS

Incision length, operative time and blood loss in patients of the observation group were significantly lower than the control group (p < 0.05). The kyphosis Cobb's angle was found to be reduced in a time-dependent manner in both groups, however, patients in the observation group achieved a significant reduction than the control (p < 0.05). The ASIA grade of few patients in the observation group significantly (p < 0.05) improved to class E from D at the time of the end of follow-up. The patients under the class 'excellent' and 'good' of Kirkaldy-Willis criteria were significantly (p < 05) higher in the observation group (92.6%) than the control group (85.7%). Also, the patients in the Bridwell grade I and II in the observation group (88.9%) were significantly (p < 0.05) higher in comparison with control group (81%). The prevalence of postoperative complications was significantly lower in the observation group (18.5%) when compared with the control group (28.6%).

CONCLUSIONS

Our results indicate that one-stage posterior debridement joint bone fixation therapy is an effective and safe procedure for patients with spinal tuberculosis and lumbar compression; this method is worthy of clinical application.

MiR-485-3p and miR-485-5p suppress breast cancer cell metastasis by inhibiting PGC-1α expression

Breast cancer is the worldwide leading cause of cancer mortality in women. The majority of deaths from breast cancer arise from metastasis of local tumors. Cancer cells support their rapid proliferation by diverting metabolites into anabolic pathways, but during cancer metastasis, the proliferative program of invasive cancer cells is suspended for a migratory phenotype. In this study, we demonstrated that both mature forms of miRNA-485, miR-485-3p and miR-485-5p were involved in regulating mitochondrial respiration, cell migration and cell invasion in breast cancer cells by directly targeting and inhibiting the expression of PGC-1α. Specifically, the expression levels of both miR-485-3p and miR-485-5p were decreased in breast cancer tissues. Overexpression of miR-485-3p and miR-485-5p suppressed mitochondrial respiration and potential for cell migration and invasion in vitro, and also inhibited spontaneous metastasis of breast cancer cells in vivo. The suppression of mitochondrial respiration and cell invasion could be partially relieved by restoration of PGC-1α expression.

Image signal transmission with Airy beams

We propose and demonstrate an approach for image signal transmission based on self-accelerating Airy beams. The spatial information is encoded in the Fourier space through a 4-f telescope system, which can circumvent obstacles to realize a self-bending signal transmission. Furthermore, the information can be retrieved from the Airy beams after propagation through a disordered scattering medium. Our experimental results agree well with theoretical predictions.

THz band-stop filter using metamaterials surfaced on LiNbO(3) sub-wavelength slab waveguide

We designed and implemented periodic bar arrays metamaterials to select appropriate frequencies of terahertz (THz) waves propagating in a LiNbO(3) sub-wavelength waveguide. The spatial and temporal electric field profiles of the THz waves were recorded using a time-resolved phase-contrast imaging system. The metamaterials can operate as a band-stop filter to realize blocking back THz waves in a band range of 0.6-1.0 THz, while transparent transmission for the fundamental mode of the slab over a range of 0.3-0.6 THz.

Dynamical deformed Airy beams with arbitrary angles between two wings

We study both numerically and experimentally the acceleration and propagation dynamics of 2D Airy beams with arbitrary initial angles between their "two wings." Our results show that the acceleration of these generalized 2D Airy beams strongly depends on the initial angles and cannot be simply described by the vector superposition principle (except for the normal case of a 90° angle). However, as a result of the "Hyperbolic umbilic" catastrophe (a two-layer caustic), the main lobes of these 2D Airy beams still propagate along parabolic trajectories even though they become highly deformed. Under such conditions, the peak intensity (leading energy flow) of the 2D Airy beams cannot be confined along the main lobe, in contrast to the normal 90° case. Instead, it is found that there are two parabolic trajectories describing the beam propagation: one for the main lobe, and the other for the peak intensity. Both trajectories can be readily controlled by varying the initial wing angle. Due to their self-healing property, these beams tend to evolve into the well-known 1D or 2D Airy patterns after a certain propagation distance. The theoretical analysis corroborates our experimental observations, and explains clearly why the acceleration of deformed Airy beams increases with the opening of the initial wing angle.

Generation of linear and nonlinear propagation of three-Airy beams

We report the first experimental demonstration of the so-called three-Airy beams. Such beams represent a two-dimensional field that is a product (rather than simple superposition) of three Airy beams. Our experiments show that, in contrast to conventional Airy beams, this new family of Airy beams can be realized even without the use of truncation by finite apertures. Furthermore, we study linear and nonlinear propagation of the three-Airy beams in a photorefractive medium. It is found that a three-Airy beam tends to linearly diffract into a super-Gaussian-like beam, while under nonlinear propagation it either turns into three intensity spots with a self-defocusing nonlinearity or evolves into a self-trapped channel with a self-focusing nonlinearity.

Reshaping the trajectory and spectrum of nonlinear Airy beams

We demonstrate theoretically and experimentally that a finite Airy beam changes its trajectory while maintaining its acceleration in nonlinear photorefractive media. During this process, the spatial spectrum reshapes dramatically, leading to negative (or positive) spectral defects on the initial spectral distribution under a self-focusing (or defocusing) nonlinearity.

Tunable self-shifting Bloch modes in anisotropic hexagonal photonic lattices

We study controllable self-shifting Bloch modes in anisotropic hexagonal photonic lattices. The shifting results from a deformed band structure due to deformation of the index distribution in each unit cell. By reconfiguration of the index profile of the unit cell, the direction in which the Bloch modes move can be controlled. Our theoretical predictions are experimentally demonstrated in hexagonal lattices optically induced in an anisotropic nonlinear crystal.

Combining transfer of TTF-1 and Pax-8 gene: a potential strategy to promote radioiodine therapy of thyroid carcinoma

Cotransfer of thyroid-specific transcription factor (TTF)-1 and Pax-8 gene to tumor cells, resulting in the re-expression of iodide metabolism-associated proteins, such as sodium iodide symporter (NIS), thyroglobulin (Tg), thyroperoxidase (TPO), offers the possibility of radioiodine therapy to non-iodide-concentrating tumor because the expression of iodide metabolism-associated proteins in thyroid are mediated by the thyroid transcription factor TTF-1 and Pax-8. The human TTF-1 and Pax-8 gene were transducted into the human thyroid carcinoma (K1 and F133) cells by the recombinant adenovirus, AdTTF-1 and AdPax-8. Re-expression of NIS mRNA and protein, but not TPO and Tg mRNA and protein, was detected in AdTTF-1-infected F133 cells, following with increasing radioiodine uptake (6.1-7.4 times), scarcely iodide organification and rapid iodide efflux (t(1/2) ≈ 8-min in vitro, t(1/2) ≈ 4.7-h in vivo). On contrast, all of the re-expression of NIS, TPO and Tg mRNA and proteins were detected in F133 cells coinfected with AdTTF-1 and AdPax-8. AdTTF-1- and AdPax-8-coinfected K1 and F133 cells could effectively accumulate radioiodine (6.6-7.5 times) and obviously retarded radioiodine retention (t(1/2) ≈ 25-30-min in vitro, t(1/2) ≈ 12-h in vivo) (P<0.05). Accordingly, the effect of radioiodine therapy of TTF-1 and Pax-8 cotransducted K1 and F133 cells (21-25% survival rate in vitro) was better than that of TTF-1-transducted cells (40% survival rate in vitro) (P<0.05). These results indicate that single TTF-1 gene transfer may have limited efficacy of radioiodine therapy because of rapid radioiodine efflux. The cotransduction of TTF-1 and Pax-8 gene, with resulting NIS-mediated radioiodine accumulation and TPO and Tg-mediated radioiodine organification and intracellular retention, may lead to effective radioiodine therapy of thyroid carcinoma.

Acceleration control of Airy beams with optically induced refractive-index gradient

We demonstrate both experimentally and theoretically controlled acceleration of one- and two-dimensional Airy beams in optically induced refractive-index potentials. Enhancement as well as reduction of beam acceleration are realized by changing the index gradient, while the beam shape is maintained during propagation through the linear optical potential. Our results of active acceleration manipulation in graded media are pertinent to Airy-type beam propagation in various environments.

Anomalous interactions of spatial gap solitons in optically induced photonic lattices

We demonstrate coherent interactions between spatial gap solitons in optically induced photonic lattices. Because of the "staggered" phase structures, two in-phase (out-of-phase) bright gap solitons can repel (attract) each other at close proximity, in contrast to soliton interaction in homogeneous media. A reversal of energy transfer direction and a transition between attractive and repulsive interaction forces can be obtained solely by changing the initial soliton separation relative to the lattice spacing.

Persistence and breakdown of Airy beams driven by an initial nonlinearity

We study the behavior of Airy beams propagating from a nonlinear medium to a linear medium. We show that an Airy beam initially driven by a self-defocusing nonlinearity experiences anomalous diffraction and can maintain its shape in subsequent propagation, but its intensity pattern and acceleration cannot persist when driven by a self-focusing nonlinearity. The unusual behavior of Airy beams is examined from their energy flow as well as the Brillouin zone spectrum of self-induced chirped photonic lattices.

Optimal control of the ballistic motion of Airy beams

We demonstrate the projectile motion of two-dimensional truncated Airy beams in a general ballistic trajectory with controllable range and height. We show that the peak beam intensity can be delivered to any desired location along the trajectory as well as repositioned to a given target after displacement due to propagation through disordered or turbulent media.

Observation of bandgap guidance of optical vortices in a tunable negative defect

We experimentally demonstrate linear bandgap guidance of optical vortices as high-gap defect modes (DMs) in two-dimensional induced photonic lattices. We show that donut-shaped vortex beams can be guided in a tunable negative (lower-index) defect, provided that the defect strength is set at an appropriate level. Such vortex DMs have fine features in the "tails" associated with the lattice anisotropy and can be considered as a superposition of dipole DMs. Our numerical results find good agreement with experimental observations.

Tuning of Bloch modes, diffraction, and refraction by two-dimensional lattice reconfiguration

We demonstrate controlled excitation of Bloch modes and manipulation of diffraction and refraction in optically induced two-dimensional photonic lattices. Solely by adjusting the bias condition, the lattice structures can be reconfigured at ease, enabling the observation of transition between Bloch modes associated with different high-symmetry points of a photonic band, and interplay between normal and anomalous diffraction as well as positive and negative refraction under identical excitation condition.

Self-trapping of optical vortices at the surface of an induced semi-infinite photonic lattice

We demonstrate self-trapping of singly-charged vortices at the surface of an optically induced two-dimensional photonic lattice. Under appropriate conditions of self-focusing nonlinearity, a singly-charged vortex beam can self-trap into a stable semi-infinite gap surface vortex soliton through a four-site excitation. However, a single-site excitation leads to a quasi-localized state in the first photonic gap, and our theoretical analysis illustrates that such a bandgap surface vortex soliton is always unstable. Our experimental results of stable and unstable topological surface solitons are corroborated by direct numerical simulations and linear stability analysis.

Saddle solitons: a balance between bi-diffraction and hybrid nonlinearity

We demonstrate self-trapping of light by simultaneously compensating normal and anomalous (saddle-shaped) diffractions with self-focusing and self-defocusing hybrid nonlinearity in optically induced ionic-type photonic lattices. Innovative two-dimensional gap solitons, named "saddle solitons," are established, whose phase and spectrum characteristics are different from all previously observed spatial solitons.

Orientation-dependent excitations of lattice soliton trains with hybrid nonlinearity

We demonstrate selective excitation of soliton trains residing in different gaps or within the same Bloch band of a new type of photonic lattice merely by changing the orientation of an input probe beam. A self-focusing and -defocusing hybrid nonlinearity as established in a nonconventionally biased photorefractive crystal leads to controlled soliton transitions from different band edges or subband edges, in good agreement with our theoretical analysis.

Self-trapping of optical vortices in waveguide lattices with a self-defocusing nonlinearity

We demonstrate the self-trapping of single- and double-charged optical vortices in waveguide lattices induced with a self-defocusing nonlinearity. Under appropriate conditions, a donut-shaped single-charged vortex evolves into a stable discrete gap vortex soliton, but a double-charged vortex turns into a self-trapped quadrupole-like structure. Spectrum measurement and numerical analysis suggest that the gap vortex soliton does not bifurcate from the edge of the Bloch band, quite different from previously observed gap spatial solitons. Our numerical findings are in good agreement with experimental observations.

Optically induced transition between discrete and gap solitons in a nonconventionally biased photorefractive crystal

We show that optically induced photonic lattices in a nonconventionally biased photorefractive crystal can support the formation of discrete and gap solitons owing to a mechanism that differs from the conventional screening effect. Both the bias direction and the lattice orientation can dramatically influence the nonlinear beam-propagation dynamics. We demonstrate a transition from self-focusing to -defocusing and from discrete to gap solitons solely by adjusting the optical-beam orientation.

Elliptical discrete solitons supported by enhanced photorefractive anisotropy

We demonstrate elliptical discrete solitons in an optically induced two-dimensional photonic lattice. The ellipticity of the discrete soliton results from enhanced photorefractive anisotropy and nonlocality under a nonconventional bias condition. We show that the ellipticity and orientation of the discrete solitons can be altered by changing the direction of the lattice beam and/or the bias field relative to the crystalline c-axis. Our experimental results are in good agreement with the theoretical prediction.

Observation of dipole-like gap solitons in self-defocusing waveguide lattices

We observe dipole-like gap solitons in two-dimensional waveguide lattices optically induced with a self-defocusing nonlinearity. Under appropriate conditions, two mutually coherent input beams excited in neighboring lattice sites evolve into a self-trapped state, whose spatial power spectrum and stability depend strongly on the initial excitation conditions. Our experimental observations are compared with numerical simulations.

Nonlinear spectrum reshaping and gap-soliton-train trapping in optically induced photonic structures

We report the first theoretical prediction and experimental demonstration of gap soliton trains in a self-defocusing photonic lattice. Without a priori spectral or phase engineering, a stripe beam whose spatial power spectrum lies only in one transverse direction evolves into a gap soliton train with power spectrum growing also in the orthogonal direction due to nonlinear transport and spectrum reshaping. Our results suggest that, in nonlinear k-space evolution, energy can transfer not only between regions of normal and anomalous diffraction, but also from initially excited regions to initially unexcited regions.

Elliptical solitons in nonconventionally biased photorefractive crystals

We theoretically predict and experimentally observe the two-dimensional (2-D) bright solitons in a nonconventionally biased strontium barium niobate (SBN) crystal. A theory describing light propagating in an SBN crystal with a bias field along an arbitrary direction is formulated. Then the existence of 2-D bright solitons in such a crystal is numerically verified. By employing digital holography, the index changes induced by Gaussian beams in an SBN crystal under different biasing conditions are visualized. Finally, skewed elliptical solitons are experimentally demonstrated.

Symmetric and antisymmetric soliton states in two-dimensional photonic lattices

We study the dynamics of off-site excitation in an optically induced waveguide lattice. A single beam centered between two waveguides leads to an asymmetric beam profile as the nonlinearity reaches a threshold. When two probe beams are launched in parallel into two nearby off-site locations, they form symmetric or antisymmetric (twisted) soliton states, depending on their relative phase. A transition of intensity pattern from on-site to off-site locations is also observed as the lattice is excited by a quasi-one-dimensional plane wave.

Enhanced second-harmonic generation by means of high-power confinement in a photovoltaic soliton-induced waveguide

We present the first experimental demonstration of enhanced second-harmonic generation (SHG) by means of power confinement with a femtosecond laser in a photovoltaic soliton-induced waveguide. A dark spatial soliton created with a weak cw laser beam in a photovoltaic lithium niobate crystal induces an efficient waveguide for SHG, leading to a 60% enhancement of the conversion efficiency.

[Internal strontium-89 radiotherapy for malignant bony metastasis]

OBJECTIVE

This work was done to evaluate the indication, effectiveness, and side effects of internal radiotherapy with radioactive nuclide strontium-89 (89Sr) in patients with malignant metastasis in the bone.

METHODS

Fifty-six patients with skeletal metastasis received this internal radiotherapy. The patients were observed and followed up with respect to pain control, lesion improvement and side effects.

RESULTS

The overall effective rate of pain control was 76.8% with the effective rate of prostatic cancer and breast cancer higher than 80%. The lesions in 81.8% patients as assessed by SPECT imaging, were improved. The mild lowering of white cells, platelets and red cells was the main side effect.

CONCLUSION

Internal radiotherapy with 89Sr is very useful for patients with malignant cancer metastasis in the bone.

Sexual behaviour and contraceptive use among unmarried, young women migrant workers in five cities in China

This paper reports the results of exploratory research on reproductive and sexual health knowledge and sexual behaviour of young, unmarried women who migrate to cities from rural areas for work, and their access to and needs in relation to family planning in Beijing, Guangzhou, Shanghai, Guiyang and Taiyuan, in China. Focus group discussions were conducted with 146 young women aged 16-25 and 58 in-depth interviews with key informants. Some of the young female migrant workers were sexually active and living with their boyfriends, most of whom expected to marry each other. Most of the women lacked basic information about reproduction and contraception, and did not know where or how to obtain contraception. There were social, psychological and economic barriers to accessing services. Only a small proportion of those who were unmarried were using contraception, so induced abortion was often the outcome of unprotected premarital sex. Pleasing male partners also played an important role in unprotected sex. The training, attitudes and approach of the entire family planning service system in relation to unmarried and young people in China, including this migrant population, needs to be reorientated so as to provide them with appropriate and adequate services.

The mechanism of the effect of obesity in knee osteoarthritis: the mediating role of malalignment

OBJECTIVE

Obesity is most strongly linked to osteoarthritis (OA) at the knee. Varus malalignment was examined as a possible local mediator that may increase the impact of body weight at the knee, versus the hip or ankle. Compartment load distribution is more equitable in valgus than in varus knees, and valgus knees may better tolerate obesity. We therefore tested whether 1) body mass index (BMI) is correlated with OA severity in varus knees, 2) the BMI-OA severity correlation is weaker in valgus than in varus knees, 3) BMI is correlated with the severity of varus malalignment, and 4) the BMI-medial tibiofemoral OA severity relationship is reduced after controlling for varus malalignment.

METHODS

In 300 community-recruited patients with knee OA, 2 groups (varus and valgus) were identified based on dominant knee alignment on a full-limb radiograph, i.e., the angle formed by the intersection of the femoral and tibial mechanical axes. Severity of knee OA was assessed by measurement of the narrowest joint space width on radiographs of knees in a fluoroscopy-confirmed semiflexed position.

RESULTS

Alignment direction was symmetric (or neutral in 1 limb) in 87% of patients. One hundred fifty-four patients had varus knees and 115 had valgus knees. BMI correlated with OA severity in the varus group (r = -0.29, P = 0.0009) but not in the valgus group (r = -0.13, P = 0.17). BMI correlated with malalignment in those with varus knees (r = 0.26) but not in those with valgus knees (r = 0.16). The partial correlation of BMI and OA severity, controlling for sex, was reduced from 0.24 (P = 0.002) to 0.04 (P = 0.42) when varus malalignment was added to the model.

CONCLUSION

BMI was related to OA severity in those with varus knees but not in those with valgus knees. Much of the effect of BMI on the severity of medial tibiofemoral OA was explained by varus malalignment, after controlling for sex. Whether it precedes or follows the onset of disease, varus malalignment is one local factor that may contribute to rendering the knee most vulnerable to the effects of obesity.

The effect of gestational parity on FEV1 in a group of healthy volunteer women

In the past, studies utilizing within-subject comparisons of small groups of pregnant women showed that forced expiratory volume in 1 s (FEV1) remained essentially unchanged during pregnancy. However, one of the findings from an epidemiological study was that women with greater number of children experienced a faster decline of FEV1. The aim of this study was to examine the effect of parity on FEV1 in a group of healthy volunteer women. To this end, cross-sectional multiple regression analyses of data from 397 healthy women participants in the Baltimore Longitudinal Study of Aging (BLSA) with a mean (range) age of 47.7 (18-92) years were performed. Similar analyses were done using the younger (50 years or less) and the older (> 50 years) subgroups. After controlling for age, height, weight, and smoking, parity as a dichotomous variable was associated with a higher FEV1 in women of child-bearing age (0.139 1; P = 0.02) but not in the older women. There was a modest link with the number of children (P = 0.05), with the first child possibly having the greatest effect on FEV1. We could not account for the effect of parity on FEV1 by the educational level, occupation, health status of the women, or by the presence of a cohort effect. Thus the nulliparous state is associated with lower FEV1 in this group of healthy adult women of child-bearing age.

Laxity in healthy and osteoarthritic knees

OBJECTIVE

Although it is a cause of osteoarthritis (OA) in animal models, laxity in human knee OA has been minimally evaluated. Ligaments become more compliant with age; whether this results in clinical laxity is not clear. In theory, laxity may predispose to OA and/or result from OA. Our goals were to examine the correlation of age and sex with knee laxity in control subjects without OA, compare laxity in uninvolved knees of OA patients with that in older control knees, and examine the relationship between specific features of OA and knee laxity.

METHODS

We assessed varus-valgus and anteroposterior laxity in 25 young control subjects, 24 older control subjects without clinical OA, radiographic OA, or a history of knee injury, and 164 patients with knee OA as determined by the presence of definite osteophytes. A device was designed to assess varus-valgus laxity under a constant varus or valgus load while maintaining a fixed knee flexion angle and thigh and ankle immobilization. Radiographic evaluations utilized protocols addressing position, beam alignment, magnification, and landmark definition; the semiflexed position was used, with fluoroscopic confirmation.

RESULTS

In the controls, women had greater varus-valgus laxity than did men (3.6 degrees versus 2.7 degrees; 95% confidence interval [95% CI] of difference 0.38, 1.56; P = 0.004), and laxity correlated modestly with age (r = 0.29, P = 0.04). Varus-valgus laxity was greater in the uninvolved knees of OA patients than in older control knees (4.9 degrees versus 3.4 degrees; 95% CI of difference 0.60, 2.24; P = 0.0006). In OA patients, varus-valgus laxity increased as joint space decreased (slope -0.34; 95% CI -0.48, -0.19; P < 0.0001) and was greater in knees with than in knees without bony attrition (5.3 degrees versus 4.5 degrees; 95% CI of difference 0.32, 1.27; P = 0.001).

CONCLUSION

Greater varus-valgus laxity in the uninvolved knees of OA patients versus older control knees and an age-related increase in varus-valgus laxity support the concept that some portion of the increased laxity of OA may predate disease. Loss of cartilage/bone height is associated with greater varus-valgus laxity. These results raise the possibility that varus-valgus laxity may increase the risk of knee OA and cyclically contribute to progression.

Does laxity alter the relationship between strength and physical function in knee osteoarthritis?

OBJECTIVE

Since strengthening interventions have had a lower-than-expected impact on patient function in studies of knee osteoarthritis (OA) and it is known that laxity influences muscle activity, this study examined whether the relationship between strength and function is weaker in the presence of laxity.

METHODS

One hundred sixty-four patients with knee OA were studied. Knee OA was defined by the presence of definite osteophytes, and patients had to have at least a little difficulty with knee-requiring activities. Tests were performed to determine quadriceps and hamstring strength, varus-valgus laxity, functional status (Western Ontario and McMaster Universities Osteoarthritis Index Physical Functioning subscale [WOMAC-PF] and chair-stand performance), body mass index, and pain. High and low laxity groups were defined as above and below the sample median, respectively.

RESULTS

Strength and chair-stand rates correlated (r = 0.44 to 0.52), as did strength and the WOMAC-PF score (r = -0.21 to -0.36). In multivariate analyses, greater laxity was consistently associated with a weaker relationship between strength (quadriceps or hamstring) and physical functioning (chair-stand rate or WOMAC-PF score).

CONCLUSION

Varus-valgus laxity is associated with a decrease in the magnitude of the relationship between strength and physical function in knee OA. In studies examining the functional and structural consequences of resistance exercise in knee OA, stratification of analyses by varus-valgus laxity should be considered. The effect of strengthening interventions in knee OA may be enhanced by consideration of the status of the passive restraint system.

Non-inherited maternal HLA antigens and protection against sensitisation

To test the hypothesis that non-inherited maternal antigens (NIMAs), which reportedly afford protection against sensitisation by random transfusions, can provide protection against repetitive antigenic exposure of donor-specific transfusion (DST), 140 DST patients whose donors were mismatched for NIMAs and 71 whose donors were mismatched for non-inherited paternal antigens (NIPAs) were studied. The rate of sensitisation in the two groups of patients was similar (22.1% vs 15.5%). There was no difference in sensitisation to NIMAs and NIPAs between patients who received azathioprine and those who did not. The formation of donor specific HLA antibody was comparable in the two groups. After kidney transplantation there were no differences in 1-year graft survival or the incidence of rejection episodes. These findings suggest that NIMAs do not provide lifelong protection against subsequent repetitive antigen challenge and sensitisation.