Nanocrystalline hydroxyapatite for bone repair: an animal study

Abstract Hydroxyapatite has become the most common material to replace bone or to guide its regeneration. Nanocrystalline hydroxyapatite suspension had been introduced in the clinical use recently under the assumption that small dimension of crystals could improve resorption. We studied the resorption and osteointegration of the nanocrystalline hydroxyapatite Ostim in a rabbit model. The material was implanted either alone or in combination with autogenic or allogenic bone into distal rabbit femora. After survival time of 2, 4, 6, 8 and 12 weeks the implants had been evaluated by light and electron microscopy. We observed a direct bone contact as well as inclusion into soft tissue. But we could observe no or only marginal decay and no remarkable resorption in the vast majority of implants. In situ the nanocrystalline material mostly formed densely packed agglomerates which were preserved once included in bone or connective tissue. A serious side effect was the initiation of osteolysis in the femora far from the implantation site causing extended defects in the cortical bone.

Single-shot optical conductivity measurement of dense aluminum plasmas

The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.

Structure of 240Pu: evidence for octupole phonon condensation?

The expanded level structure of 240Pu available from the present study highlights the role of strong octupole correlations in this nucleus. In addition to a delayed alignment in the yrast band, the observations include the presence of both I(+)-->(I-1)(-) and I(-)-->(I-1)(+)E1 transitions linking states of the yrast and negative-parity bands at high spin and the presence of an additional even-spin, positive-parity band deexciting exclusively to the negative-parity sequence. The observations appear to be consistent with expectations based on the recently proposed concept of octupole phonon condensation.

An evaluation of the role of smoking context on a biobehavioral index of distress tolerance

The present study evaluated the effect of smoking deprivation on a biobehavioral index of distress tolerance, breath-holding duration, among 43 adult smokers in a repeated measures test (Session 1=smoking-as-usual, Session 2=12-h smoking deprivation). We theorized that distress tolerance is a context-dependent individual difference variable whose expression varies prospectively, within-individuals, as a function of smoking context. As predicted, participants' breath-holding duration was significantly shorter during an experimental session that immediately followed a 12-h smoking deprivation period than during a smoking-as-usual session. Furthermore, we theorized that among individuals with a pre-existing diathesis (i.e., psychiatric symptoms), smoking deprivation may activate a vulnerability process that decreases capacity to tolerate distress; in the absence of this stressor, these psychiatrically vulnerable smokers may express variable levels of distress tolerance. As predicted, we observed that level of psychiatric symptoms was significantly negatively correlated with breath-holding duration during the smoking deprivation, but not the smoking-as-usual session. These data advance our understanding of smoking and distress tolerance and the context-dependent phenomenology of distress tolerance.

Limits on spin-dependent WIMP-nucleon cross sections from the XENON10 experiment

XENON10 is an experiment to directly detect weakly interacting massive particles (WIMPs), which may comprise the bulk of the nonbaryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with 129Xe and 131Xe from 58.6 live days of operation at the Laboratori Nazionali del Gran Sasso. Based on the nonobservation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of approximately 10 GeV/c2-2 TeV/c2 as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

Introducing an asymmetric cleft lift technique as a uniform procedure for pilonidal sinus surgery

BACKGROUND AND AIMS

Asymmetric techniques for surgery in pilonidal sinus disease (PSD) have been reported to provide better results than simple excision and closure in the midline. The aim of this retrospective study was to evaluate the results after introducing the Bascom asymmetric cleft lift procedure in our hospital on a day care basis.

MATERIAL AND METHODS

From a total of 33 patients operated from April 2002 to September 2004 with the Bascom asymmetric cleft lift technique, we were able to contact 29 who were invited to a follow up study. Eighteen (62%) of these patients accepted a consultation in the outpatient clinic while 11 (38%) were interviewed by phone.

RESULTS

At follow up mean 17 (range 10-27) months after the operation 24 (83%) of the wounds were healed while recurrences were present in 5 (17%) of the patients. In two of the patients with recurrences errors in the procedures were identified. Further results related to pre-, per- and postoperative conditions are discussed in this paper.

CONCLUSION

Early results after surgery for PSD with the Bascom asymmetric cleft-lift technique are promising. The technique has now become our standard procedure for treating chronic, symptomatic PSD.

[Radiological mid-term results of total knee arthroplasty with femoral components of different materials]

AIM

The present work aimed at evaluating the radiological mid-term results of femoral components of different materials in an identically designed total knee system.

METHOD

31 knees with zirconium femoral components and 32 standard femoral components were evaluated about 4 years following surgery using the Roentgenographic Evaluation and Scoring System of the Knee Society.

RESULTS

In both groups, the implant position was correct. There was a statistically significant higher rate of radiolucent lines in zones 1 and 4 at the tibia site in the zirconium group.

CONCLUSION

Our clinical results disagree with the results of biomechanical studies of the same type of prosthesis. However, there are some findings from animal studies showing that zirconium ions may inhibit the mineralisation of osteoid, which could be an explanation for the higher rate of radiolucent lines seen in the present study.

First results from the XENON10 dark matter experiment at the Gran Sasso National Laboratory

The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon to discriminate signal from background down to 4.5 keV nuclear-recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006, and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross section of 8.8x10(-44) cm2 for a WIMP mass of 100 GeV/c2, and 4.5x10(-44) cm2 for a WIMP mass of 30 GeV/c2. This result further constrains predictions of supersymmetric models.

Automatization of nanotomography

An approach for automated nanotomography, a layer-by-layer imaging technique based on scanning probe microscopy (SPM), is presented. Stepwise etching and imaging is done in situ in a liquid cell of an SPM. The flow of etching and rinsing solutions after each etching step is controlled with solenoid valves which allow for an automated measuring protocol. The thermal drift and the drift of the piezo scanner is corrected by applying offsets calculated from the cross correlation coefficients between successive images. As an example, we have imaged human bone with approximately 10 nm resolution using tapping mode SPM and successive etching with hydrochloric acid.

High-resolution myocardial perfusion imaging at 3 T: comparison to 1.5 T in healthy volunteers

The purpose of this study was to evaluate high-resolution (HR) myocardial first-pass perfusion in healthy volunteers at 3 T compared to a typical clinical imaging protocol at 1.5 T, with respect to overall image quality and the presence of subendocardial dark rim artifacts. Myocardial first-pass rest perfusion studies were performed at both field strengths using a T1-weighted saturation-recovery segmented k-space gradient-echo sequence combined with parallel imaging (Gd-DTPA 0.05 mmol/kg). Twenty-six healthy volunteers underwent (1) a HR perfusion scan at 3 T(pixel size 3.78 mm(2)) and (2) a standard perfusion approach at 1.5 T(pixel size 9.86 mm(2)). The contrast enhancement ratio (CER) and overall image quality (4-point grading scale: 4: excellent; 1: non-diagnostic) were assessed, and a semiquantitative analysis of dark rim artifacts was performed for all studies. CER was slightly higher (1.31 +/- 0.32 vs. 1.14 +/- 0.34; p<0.01), overall image quality was significantly improved (3.03 +/- 0.43 vs. 2.37 +/- 0.39; p<0.01), and the number of dark rim artifacts (139 +/- 2.09 vs. 243 +/- 2.33; p<0.01) was significantly reduced for HR perfusion imaging at 3 T compared to the standard approach at 1.5 T. HR myocardial rest perfusion at 3 T is superior to the typical clinical perfusion protocol performed at 1.5 T with respect to the overall image quality and presence of subendocardial dark rim artifacts.

[Cage failure following replacement of the third lumbar vertebral body in Hodgkin's disease]

AIM

We present a case report and the histological analysis of cage failure following vertebral body replacement in Hodgkin's disease.

METHOD

In a 35-year-old patient with a single metastasis of Hodgkin's disease replacement of the third lumbar vertebral body (Harms-titanium-mesh-cage, DePuy Acromed, completely filled with autogenous spongiosa from the iliac crest) was performed. 51 months postoperatively, the patient presented with acute back pain without trauma. The X-ray showed a collapse of the Harms-titanium-mesh-cage. The cage fragments had caused ventral dislocation of the main blood vessels and dura compression without neurological deficits. After the replacement of the failed Harms-cage (Synex, Synthes) histological analysis (light microscope, non-decalcified horizontal cuts, thickness of 150-200 microm, Giemsa und van Gieson staining) was done.

RESULT

The histology showed a remodelling of new bone in the area of the endplates without contact to the cage wall. In the region of the cage corpus, bony necrosis and connective tissue rich in cells was found.

CONCLUSION

Bridging fusion in vertebral body replacement cages is not proven. As a result cage failure may occur. Therefore, in tumour patients with high live expectancy, Palacos filling of the cages should be discussed.

Functional characterization of novel presenilin-2 variants identified in human breast cancers

We identified in breast cancer cases two germline alterations, R62H and R71W, in presenilin-2 (PS-2), a gene involved in familial Alzheimer's disease (FAD). The role of these alleles in FAD is unclear, but neither allele affected Abeta(42)/Abeta(40) ratio. However, both R62H and R71W alterations compromised PS-2 function in Notch signaling in Caenorhabditis elegans and cell growth inhibition in mouse embryonic fibroblasts, and these effects were dependent on gene dosage. We found that both alterations enhanced the degradation of the PS-2 full-length protein, indicating that they may have a loss-of function effect. The effect of the R71W alteration was noticeably stronger, and we observed an almost threefold higher frequency of this allele in breast cancer cases versus controls, but this difference did not reach statistical significance. Nonetheless, these results collectively suggest that the novel PS-2 alleles described here, especially R71W, affect PS-2 function and may potentially confer a moderate risk of susceptibility to breast cancer.

[Axial load in case of press-fit fixation of the ACL graft--a fundamental study]

AIM

The aim of this study was the determination of the axial fixation load resting on smooth press-fit dowels needed for fixation of the patellar tendon graft (BTB) in order to reach the same fixation properties compared to the interference screw on anterior cruciate ligament (ACL) plasty.

METHOD

Bovine test specimens with 27 BTB grafts fixed in tibial drill holes were used and divided in 3 groups: interference screw, and press-fit cylinder (Ø 7 mm) with 150 N and 100 N axial loads. Prior to fixation, impactation of the transplant into bone was carried out. Failure testing was done in a tensiometer at a cross-head speed of 50 mm/min. Determinations of peak load and stiffness were also made.

RESULTS

Similar peak loads and stiffness were reached on introducing a press-fit dowel (slashed circle 7 mm) with 100 N and 150 N axial load compared to interference screw fixation of the BTB graft. Peak load: 988.1 N +/- 365.1 (screw) versus 1 210.4 N +/- 292.4 (dowel 150 N) and 1 109.8 N +/- 505.4 (dowel 100 N). Stiffness: 86.4 N/mm +/- 20.5 (screw) versus 102.4 N/mm +/- 15.2 (dowel 150 N) and 77.1 N/mm +/- 11.0 (dowel 100 N). There was no significant difference.

CONCLUSION

When introducing a press-fit dowel (slashed circle 7 mm) with 100 N axial load into a preformed bone bed, the same fixation properties are reached as in the case of an interference screw on BTB-ACL plasty.

The accuracy of dynamic wedge dose computation in the ADAC Pinnacle RTP system

The nonphysical wedge is a modality that uses computer‐controlled jaw motion to generate wedge‐shaped dose distributions. There are Varian enhanced dynamic wedges (EDWs) and Siemens virtual wedges (VWs). We recently commissioned dynamic wedges on both Varian and Siemens LINACs. The beam data, acquired with a Wellhöfer chamber array and a Sun Nuclear profiler, are used for modeling in the ADAC Pinnacle system. As recommended by ADAC, only a limited number of beam data is measured and used for beam modeling. Therefore, the dose distributions of dynamic wedges generated by Pinnacle must be examined. Following the commissioning of the dynamic wedges, we used Pinnacle to generate a number of dose distributions with different energies, wedge angles, field sizes, and depths. The computed data from Pinnacle are then compared with the measured data.

The deviations of the output factor in all square and rectangular fields are mostly within 2.0% for both EDW and VW. For asymmetric fields, the deviations are within 3%. However, exceptions of differences more than 3% have been found in a larger field and large wedge combinations. The precision of the beam profiles generated by Pinnacle is also evaluated. As a result of this investigation, we present a scope of quality assurance tests that are necessary to ensure acceptable consistency between the delivered dose and the associated treatment plan when dynamic wedges are applied.

PACS numbers: 8753 Dq, 87.53.Xd

A home-based nutrition intervention to increase consumption of fruits, vegetables, and calcium-rich foods in community dwelling elders

OBJECTIVE

To increase fruit, vegetable, and calcium-rich food consumption in community-dwelling, functionally impaired elderly.

DESIGN

Six-month, home-based nutrition intervention study.

SUBJECTS

Seventy men and women older than age 69 years were randomized to either a nutrition education intervention (n = 38) or a control group that received an exercise intervention (n = 32).

INTERVENTION

Nutrition education was designed to increase fruit, vegetable, and calcium-rich food consumption.

MAIN OUTCOME MEASURES

Food intake was assessed by a food frequency questionnaire. Fasting blood measures of nutrients and carotenoids were performed. Statistical Analysis Two-group randomized controlled trial with pre-test and post-test design and intention-to-treat analysis. Analysis of covariance to was used to assess differences between the two groups. Baseline and change partial correlation coefficients were performed between intake and blood nutrient levels. Paired t tests were conducted to test within-group changes.

RESULTS

Compared with the exercise group, subjects in nutrition group increased their self-reported intake of fruits by 1.1 +/- 0.2 (mean +/- SEM) servings per day (2.8 to 3.9, P = .01), vegetables 1.1 +/- 0.2 servings per day (2.3 to 3.4, P = .001), and milk/dairy 0.9 +/- 0.2 servings per day (3.0 to 3.9, P = .001). There was an increase in the dietary intake of alpha-carotene and beta-carotene in the nutrition group and this correlated with the increase in blood concentrations of alpha-carotene and beta-carotene (P < or = .02; r = 0.33 and r = 0.33, respectively).

CONCLUSION

The results of this study suggest that it is possible to improve the dietary intake of community dwelling elders to include more fruits, vegetables, and calcium-rich foods. Recommendations for increasing consumption of fruits, vegetables, and calcium-rich foods should be specific and individualized to meet the dietary pattern and lifestyle of the individual. Compliance should be encouraged with record keeping as well as through continuous monitoring and positive reinforcement.

Relativistic effects and two-body currents in (H)((-->)e(')p)n using out-of-plane detection

Measurements of the (2)H((-->)e,e(')p)n reaction were performed with the out-of-plane magnetic spectrometers (OOPS) at the MIT-Bates Linear Accelerator. The longitudinal-transverse, f(LT) and f(')(LT), and the transverse-transverse, f(TT), interference responses at a missing momentum of 210 MeV/c were simultaneously extracted in the dip region at Q2 = 0.15 (GeV/c)(2). In comparison to models of deuteron electrodisintegration, the data clearly reveal strong effects of relativity and final-state interactions and the importance of two-body meson-exchange currents and isobar configurations. We demonstrate that such effects can be disentangled by extracting these responses using the novel out-of-plane technique.

A locus affecting obesity in human chromosome region 10p12

AIMS/HYPOTHESIS

Obesity is a complex trait influenced by multiple genes. We evaluated linkage in three regions of human chromosome 10 previously linked to obesity-related phenotypes.

METHODS

We conducted non-parametric linkage analysis of obesity-related phenotypes in cohorts of 170 European-American and 43 African-American families having extremely obese and normal weight subjects.

RESULTS

We found support for linkage of an obesity phenotype (BMI > or = 27 kg/m2) in both cohorts, as well as in a combined analysis (European-American cohort, Z = 1.90, p = 0.03; African-American cohort, Z = 2.25, p = 0.014; combined cohort, Z = 2.55, p = 0.005).

CONCLUSION/INTERPRETATION

These results confirm previous reports of linkage in French and German families. The consistency of results across these four cohorts supports the localization of a quantitative trait locus influencing obesity to human chromosome region 10p12.