Peri-interventional ischemic stroke after coronary angiography: a large-scale nationwide cohort analysis from 2006 to 2020

Background

Ischemic stroke after coronary angiography is a life-threatening complication, leading to high mortality and long-term sequelae in surviving patients. Contemporary data from a European nationwide perspective are however lacking.

Purpose

We aimed to investigate the incidence, temporal trends, and outcome of ischemic stroke complicating coronary angiography in a German nationwide cohort.

Methods

A retrospective analysis of healthcare records from 2006–2020 based on ICD-10 and OPS codes obtained from the German Federal Statistical Office was carried out. Patients ≥18 years of age hospitalized for coronary angiography (both diagnostic and percutaneous interventions) were included in this analysis. Ischemic stroke events as well as co-morbidities were identified using ICD-10 and OPS codes. The outcome of interest was in-hospital mortality. Multivariable logistic regressions were computed for the association of ischemic stroke with in-hospital mortality adjusting for age, gender, hypertension, hyperlipoproteinemia, and diabetes mellitus.

Results

Overall 5,098,751 cases of patients undergoing coronary angiography (mean age 68.7±11.4 years; 28.0% female) between 2006 and 2020 were included. Ischemic stroke occurred in 3,808 (0.07%) patients. In comparison, individuals who suffered from peri-interventional ischemic stroke were older (70.8±11.1 vs. 68.7±11.4; p<0.001), more likely female (33.4% vs. 27.9%; p<0.001), and differed significantly according to their clinical characteristics (see Table 1). Patients with ischemic stroke had a significantly longer in-hospital stay (18.3±15.5 vs. 6.4±8.0 days; p<0.001), and higher rates of in-hospital mortality (18.0% vs. 3.2%; p<0.001) compared to patients without ischemic stroke. After multivariable adjustment, ischemic stroke remained independently associated with a higher risk of in-hospital mortality with an Odds ratio of 6.5 (95% Confidence Interval: 5.9, 7.1; p<0.001). Also, incidence of peri-interventional stroke increased gradually from 0.03% in 2006 to 0.12% in 2020 (see Figure 1).

Conclusion

In a contemporary nationwide cohort of patients hospitalized for coronary angiography spanning 15 years, the incidence of ischemic stroke remained low, although a gradual increase from 2006 to 2020 was documented. The occurrence of ischemic stroke was independently associated with a markedly increased risk of in-hospital mortality. These findings might be helpful in evaluating patients undergoing coronary angiography and to reduce the high mortality and morbidity associated with this complication in future.

Funding Acknowledgement

Type of funding sources: None.

Target populations and treatment cost for bempedoic acid and PCSK9 inhibitors: a simulation study in a contemporary CAD cohort

Background

The 2019 ESC dyslipidaemia guidelines recommend a more intense LDL-cholesterol (LDL-C) reduction for patients with coronary artery disease (CAD). As a result the need for PCSK9 inhibitors (PCSK9i) is projected to increase significantly, with a concomitant substantial impact on treatment cost. Adding the novel lipid lowering agent bempedoic acid (BA) to established oral lipid lowering therapy could provide an affordable alternative to PCSK9i to attain the LDL-C treatment target, particularly in patients with statin intolerance.

Aims

To quantify the target populations for BA and PCSK9i as well as the related treatment costs to achieve the LDL-C target of the 2019 ESC dyslipidaemia guidelines assuming addition of BA to lipid lowering medication.

Methods

We included 1922 patients (mean age 69.3 years) with angiographically documented CAD from an observational cohort study ongoing since 2015. A Monte Carlo simulation incorporating an algorithm for intensification of lipid lowering medication was applied in order to achieve the LDL-C treatment goal of <55 mg/dL and a ≥50% reduction from baseline LDL-C. The algorithm added sequentially a statin, ezetimibe, optionally BA, and a PCSK9i, and considered both partial and total statin intolerance. Two scenarios of treatment intensification were simulated for both a moderate (2% full and 10% partial) and a high rate of statin intolerance (12% full): 1. without BA and 2. with BA. Treatment costs and preventable events were calculated for each scenario and the following annual medication cost in Germany: €6049 evolocumab, €1551 BA.

Results

Figure 1 displays the baseline LDL-C distribution (median LDL-C 86.0 mg/dL) and lipid lowering medications. The need for PCSK9i in scenario 1 would be 41.4% for a moderate and 46.1% for a high rate of statin intolerance. Addition of BA in scenario 2 would reduce the need for PCSK9i to 25.3% and 29.4%. Figure 2 displays the LDL-C distributions and lipid lowering medications for scenarios 1 and 2 assuming a moderate rate of statin intolerance. Use of BA would lower the annual overall treatment cost incurred through use of PCSK9i ± BA per 1,000,000 CAD patients by 13.3% and 10.5%. The cost per prevented event in the entire cohort would be lower (−5.0 and −6.3%), however at the price of less prevented cardiovascular events (−8.7% and −4.5%). Amongst patients with full statin intolerance, the cost per prevented event would be reduced (−6.8% for both rates of statin intolerance) whilst more cardiovascular events would be prevented (+7.5% and +6.9%).

Conclusion

Use of BA in patients with CAD would reduce the need for PCSK9i as well as the overall treatment cost for add-on lipid lowering therapy. The subpopulation of patients with full statin intolerance might profit particularly.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Baseline LDL-C distribution and LLMFigure 2. LDL-C and LLM after LLM intensification

Association of high-sensitivity Troponin T and I blood levels with outcome of coronary artery disease – results from the INTERCATH cohort

Background

High-sensitivity Troponin T and I (hsTnT/I) concentration is independently associated with coronary artery disease (CAD) severity and cardiovascular outcome. Here we explored whether hsTnT/I blood levels add predictive information irrespective of CAD severity and further confounders in unselected stable patients with angiographically characterized CAD.

Methods

Between 2015 and 2020, 3,012 patients undergoing coronary angiography were included in the observational Hamburg INTERCATH study. In 2,209 consecutive patients Troponin levels were quantified for hsTnT (Roche Diagnostics Elecsys) and hsTnI (Abbott Diagnostics ARCHITECT STAT). Patients presenting with acute coronary syndromes and heart transplant recipients were excluded, leaving 1,841 patients for analyses. CAD severity was graded according to the Gensini score. Major adverse cardiac events (MACE) as a composite of cardiovascular death, stroke, myocardial infarction, and coronary revascularization were defined as endpoint. Kaplan-Meier analyses stratified by hsTnT/I quartiles were performed. Multivariable Cox models were computed for the association of hsTnT/I with MACE adjusting for age, gender, arterial hypertension, hyperlipoproteinemia, smoking, diabetes mellitus, body-mass index, eGFR and Gensini Score.

Results

Mean age was 68.5±10.9 years (27.9% female). 81.1% were diagnosed with CAD by coronary angiography. Gensini score was 21.0±30.2. Median follow-up time was 4.42 years. hsTnT quartiles differentiated MACE across all categories (Figure 1A). For hsTnI, cardiovascular risk was differentiated between the lowest and highest quartiles as well as the 1st and 2nd quartile particularly beyond 24 months of follow-up (Figure 1B). However, MACE after 3 years was not associated with hsTnT after adjustment for classical cardiovascular risk factors and CAD severity (Figure 1C), whereas the hazard of MACE was increased in the 3rd and 4th hsTnI quartiles compared to the 1st quartile (HR 1.3, IQR 1.1–1.6 for both categories; Figure 1D).

Conclusion

Increasing hsTn concentration was related to intermediate term cardiovascular outcome in unselected stable patients. Only hsTnI concentration remained as independent predictor after testing for most possible confounders, including CAD severity. This data underpins the role of hsTnI in outcome prediction.

Funding Acknowledgement

Type of funding sources: None.

Risk scores for risk stratification in chronic coronary syndrome and their improvement by Gensini and SYNTAX scores

Introduction

There is a substantial residual risk in patients with chronic coronary syndrome (CCS). Risk scores could be useful tools to allocate intensified secondary preventive medications to address this residual risk. Whether their predictive value can be improved by addition of angiographic scores of the extent of coronary artery disease (CAD) is unknown.

Purpose

To test and compare the predictive value of three externally developed risk scores for CAD and to investigate the effect of addition of SYNTAX and Gensini scores.

Methods

We tested the TIMI risk score for secondary prevention (TRS 2°P), a risk score derived from the INVEST study, and the ABC-CHD model (see references 1–3) in 1280 patients with CCS from a contemporary observational CAD cohort ongoing since 2015 with a median follow-up of 3.6 years. In a second step we added SYNTAX and Gensini scores to the models. The endpoints tested were cardiovascular death and major adverse cardiovascular events (MACE), consisting of cardiovascular death, myocardial infarction and ischemic stroke.

Results

All investigated scores yielded continuously increasing event rates for MACE and cardiovascular death with increasing score points obtained. As an example Figure 1 displays 3-year rates for cardiovascular death and MACE against the points obtained in the TRS 2°P, whilst also displaying the distribution of patients amongst the risk categories. The three scores showed modest predictive value for occurrence of cardiovascular death (c-indices 0.60, 0.64, 0.70 for TRS 2°P, INVEST score, ABC-CHD score, respectively). Addition of both SYNTAX and Gensini scores to the models yielded c-indices of 0.66, 0.69 and 0.70 respectively (Figure 2a). Similar predictive values were observed for the occurrence of MACE (c-indices 0.59, 0.60, 0.64 for TRS 2°P, INVEST score, ABC-CHD score, respectively) as well after addition of both SYNTAX and Gensini scores (c-indices 0.62, 0.63, 0.64, see Figure 2b).

Conclusion

(I) Currently available risk scores are modestly predictive for the occurence of cardiovascular events in patients with CCS. (II) Addition of Gensini and SYNTAX scores improves their predictive value particularly in weaker risk scores.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2a (left) and 2b (right)

The impact of the revised ESC Dyslipidaemia Guidelines on lipid-lowering therapy: simulating the need for PCSK9 inhibition in a contemporary ASCVD cohort

Introduction

The recently updated ESC guidelines on the management of dyslipidaemias recommend a more intense LDL-cholesterol (LDL-C) reduction. For patients with atherosclerotic cardiovascular disease (ASCVD) the LDL-C goal has been revised to ≤55 mg/dl with a concomitant class IA upgrade for cost intensive PCSK9 inhibitors.

Purpose

We aim to quantify the need for PCSK9 inhibitors to achieve the revised LDL-C target compared to former ESC recommendations in ASCVD patients

Methods

We included all patients with ASCVD (angiographically documented coronary artery disease, history of peripheral artery disease or stroke) from an observational cohort study ongoing since 2015. A simulation treatment algorithm adding sequentially a high intensity statin, ezetimibe and a PCSK9 inhibitor in case of a missed treatment target was applied with consideration of both partial and total statin intolerance. The need for PCSK9 inhibitors was calculated for 3 recommendations: 1. LDL-C treatment target ≤55 mg/dl (ESC 2019 Guidelines), 2. LDL-C treatment target ≤70 mg/dl (ESC 2016 Guidelines) and 3. risk-based use of PCSK9 inhibitors restricted to patients with a residual LDL-C >140 mg/dl or >100 mg/dl with clinical/angiographic risk factors (ESC consensus update 2017).

Results

We included 1936 patients (mean age 69 years, 74% male). Median LDL-C at inclusion was 86 mg/dl, with 60% of patients taking lipid lowering medication (55% statin only, 4% statin + ezetimibe, 1% ezetimibe only). Table 1 shows the distribution of medications required to meet recommendations 1–3. After simulated stepwise intensification of lipid lowering therapy 99% of patients achieved the revised LDL-C target of ≤55 mg/dl, with a need of 23.5% for a PCSK9 inhibitor. For the former LDL-C target of ≤70 mg/dl the need for PCSK9 inhibitors was 10.5%. Restricting the use of PCSK9 inhibitors to the highest risk patients according to the ESC 2017 consensus statement reduced the need for PCSK9 inhibition to only 1.4% with slightly fewer patients achieving their LDL-C target (78% for ≤55 mg/dl and 91% for ≤70 mg/dl respectively).

Conclusion

The revised LDL-C treatment goals substantially increase the projected need for PCSK9 inhibitors with an unclear health economic impact. Identification of ASCVD patients with a reasonable benefit/cost-ratio of PCSK9 inhibition remains to be investigated urgently.

Funding Acknowledgement

Type of funding source: None

Low-to-moderate alcohol consumption and success in fertility treatment: a Danish cohort study

STUDY QUESTION

Does female weekly alcohol intake and binge drinking impact the chance of a successful fertility treatment?

SUMMARY ANSWER

Low-to-moderate weekly alcohol drinking and binge drinking were not associated with the chance of achieving a clinical pregnancy or a live birth among women and couples undergoing medically assisted reproduction (MAR) treatments.

WHAT IS KNOWN ALREADY

Alcohol consumption is common among women of reproductive age, even though health authorities advise women trying to conceive to abstain from drinking. A growing number of couples struggle with infertility, but it is unknown whether low-to-moderate levels of alcohol consumption and alcohol binge drinking impair success in fertility treatment.

STUDY DESIGN, SIZE, DURATION

Cohort study with prospectively collected exposure information including 1708 women and potential partners undergoing fertility treatment at the public fertility clinic, Aarhus University Hospital, 1 January 2010 to 31 August 2015. In total, data on 1511 intrauterine insemination (IUI) cycles, 2870 in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles and 1355 frozen embryo transfer cycles.

PARTTICIPANTS/MATERIALS, SETTING, METHODS

Exposure to weekly average alcohol intake was assessed from questionnaires completed by participants before the start of treatment. Outcome measures are the achievement of a clinical pregnancy and live birth in consecutive treatment cycles in the Danish national health registries, enabling complete follow-up. A modified Poisson regression with robust standard errors was used to evaluate associations between a weekly average alcohol intake and MAR outcomes, adjusting for female age, body mass index, cigarette smoking, coffee consumption, chronic diseases, level of education, and cycle number. When evaluating the association between binge drinking in the month prior to baseline and MAR outcomes the analyses were further adjusted for average weekly alcohol consumption.

MAIN RESULTS AND THE ROLE OF CHANCE

Low-to-moderate average weekly alcohol intake was not statistically significantly associated with the chance of achieving a clinical pregnancy or a live birth following IUI or IVF/ICSI treatment cycles. Compared to women abstaining from alcohol, the adjusted relative risks for achieving a live birth among those reporting 1–2, 3–7, and >7 drinks per week were 1.00 (95% CI 0.66; 1.53), 1.20 (0.76; 1.91), and 1.48 (0.56; 3.93), respectively, among women initiating IUI treatments. Among those initiating IVF/ICSI treatments, the chance for achieving a live birth among those reporting 1–2, 3–7, and >7 drinks per week were 1.00 (0.83; 1.21), 0.95 (0.75; 1.20), and 0.89 (0.53; 1.51), respectively. The chance of achieving a live birth in the first IUI or IVF/ICSI treatment cycle was unrelated to the number of binge drinking episodes in the month preceding baseline.

LIMITATIONS, REASONS FOR CAUTION

The risk of non-differential exposure misclassification, confounding, or chance cannot be ruled out. In addition, due to the low number of women reporting an intake of >7 drinks/week, the potential effect of high alcohol consumption should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

Although it remains unsettled if and how alcohol affects female reproduction, our results indicate that is not necessary to abstain from alcohol when striving for a successful outcome following fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

J.L. is supported by a fully financed Ph.D. scholarship from Aarhus University and has received funds from the A.P. Møller foundation. The funding sources had no involvement in the conduct of the article. Dr Kesmodel reports personal fees from MSD and Ferring Pharmaceuticals outside the submitted work. All other authors have no conflicts of interest to declare and all have completed the ICMJE disclosure form.

TRIAL REGISTRATION NUMBER

Not relevant.

Risk of stillbirth in low-risk singleton term pregnancies following fertility treatment: a national cohort study

OBJECTIVE

To assess the risk of stillbirth in low-risk in vitro fertilisation (IVF) pregnancies.

DESIGN

Register-based national cohort study.

SETTING

Denmark 2003-2013.

POPULATION

Cohort of 425 732 singleton pregnancies including 10 235 conceived following IVF/intracytoplasmic sperm injection (ICSI), 4521 conceived following intrauterine insemination (IUI), and 410 976 spontaneously conceived.

METHODS

Information on pregnancy, obstetrical risk factors, stillbirth, and fertility treatment was obtained from the Danish national health registers for all pregnancies after gestational week 21⁺⁶ . We estimated the overall and gestational age-specific risk of stillbirth in low-risk term pregnancies following IVF, ICSI, and IUI. Further, we estimated the association between stillbirth and IVF and ICSI respectively as well as fresh or frozen-thawed embryo transfer.

MAIN OUTCOME MEASURES

Risk of stillbirth.

RESULTS

The number of stillbirths in spontaneously conceived and IVF/ICSI low-risk term pregnancies was 525 (0.1%) and 35 (0.3%), respectively. In multivariate analysis, the risk of stillbirth in pregnancies following IVF/ICSI was increased (odds ratio 2.1, 95% CI 1.4-3.1). The risk of stillbirth was correspondingly increased in time-to-event analyses taking risk time for each fetus into account from gestational week 37 and onwards (hazard ratio 2.4, 95% CI 1.6-3.6). In sub-analyses, the risk of stillbirth was increased for pregnancies following ICSI (odds ratio 2.2, 95% CI 1.2-3.1), but not IVF (odds ratio 1.7, 95% CI 0.9-3.1).

CONCLUSION

We found a systematically increased risk of stillbirth in low-risk term pregnancies following IVF/ICSI. Whether the risk was related to the treatment or to underlying subfertility is uncertain. The results may indicate a need for obstetrical surveillance for these pregnancies when reaching term.

TWEETABLE ABSTRACT

Increased risk of stillbirth in low-risk term pregnancies following fresh cycle IVF/ICSI.

Childhood growth of singletons conceived following in vitro fertilisation or intracytoplasmic sperm injection: a systematic review and meta-analysis

BACKGROUND

Assisted reproductive techniques are associated with an increased risk of adverse pregnancy outcomes, including low birthweight and intrauterine growth restriction. Yet, the long-term follow-up on the growth of these children is limited.

OBJECTIVE

To systematically review the literature on post-neonatal height and weight among children conceived following in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment, compared with that of children born after spontaneous conception.

SEARCH STRATEGY

A systematic computerised literature search using the online databases PubMed, Embase, and Scopus.

SELECTION CRITERIA

Cohort or case-control studies with an exposed group of singletons conceived following IVF or ICSI along with a control group of spontaneously conceived singletons.

DATA COLLECTION AND ANALYSIS

Studies were reviewed by at least two authors. Meta-analyses were conducted using Cochrane Review Manager. The quality of the studies was assessed with the Newcastle-Ottawa Scale.

MAIN RESULTS

Twenty studies were included, with 13 of these eligible for meta-analyses. The meta-analyses compared 3972 children born after IVF/ICSI with 11 012 spontaneously conceived children and revealed no statistically significant difference in child weight [mean difference (MD) in weight of -160 g; 95% confidence interval (95% CI) -360, 3]. When stratifying by age of child at follow-up, we found a significant lower weight in children aged 0-4 years conceived following IVF/ICSI treatment (MD -180 g; 95% CI -320, -4), but this was no longer significant in children from 5 years of age (MD -160 g; 95% CI -580, 260). The pooled analysis revealed no statistically significant difference in childhood height.

CONCLUSIONS

In vitro fertilisation/ICSI was not associated with long-term weight and height.

TWEETABLE ABSTRACT

Children born following IVF/ICSI do not have impaired long-term weight or height compared with spontaneously conceived children.

Quantifying Bulk Electrode Strain and Material Displacement within Lithium Batteries via High-Speed Operando Tomography and Digital Volume Correlation

Tracking the dynamic morphology of active materials during operation of lithium batteries is essential for identifying causes of performance loss. Digital volume correlation (DVC) is applied to high-speed operando synchrotron X-ray computed tomography of a commercial Li/MnO2 primary battery during discharge. Real-time electrode material displacement is captured in 3D allowing degradation mechanisms such as delamination of the electrode from the current collector and electrode crack formation to be identified. Continuum DVC of consecutive images during discharge is used to quantify local displacements and strains in 3D throughout discharge, facilitating tracking of the progression of swelling due to lithiation within the electrode material in a commercial, spiral-wound battery during normal operation. Displacement of the rigid current collector and cell materials contribute to severe electrode detachment and crack formation during discharge, which is monitored by a separate DVC approach. Use of time-lapse X-ray computed tomography coupled with DVC is thus demonstrated as an effective diagnostic technique to identify causes of performance loss within commercial lithium batteries; this novel approach is expected to guide the development of more effective commercial cell designs.

Synthesis, characterization and theoretical studies of 5-(benzylthio)-1-cylopentyl-1H-tetrazole

In this study, 5-(benzylthio)-1-cylopentyl-1H-tetrazole (5B1C1HT) have been synthesized. Boiling points of the obtained compound have been determined and it has been characterized by FT-IR, (1)H NMR, (13)C-APT and LC-MS spectroscopy techniques. The FT-IR, (1)H NMR and (13)C-APT spectral measurements of the 5B1C1HT compound and complete assignment of the vibrational bands observed in spectra has been discussed. The spectra were interpreted with the aid of normal coordinate analysis following full structure optimization and force field calculations based on Density Functional Theory (DFT) at 6-311++G(**), cc-pVDZ and cc-pVTZ basis sets. The optimized geometry with 6-311++G(**) basis sets were used to determine the total energy distribution, harmonic vibrational frequencies, IR intensities.

The association of pre-pregnancy alcohol drinking with child neuropsychological functioning

OBJECTIVE

To examine the effects of pre-pregnancy alcohol drinking on child neuropsychological functioning.

DESIGN

Prospective follow-up study.

SETTING AND POPULATION

154 women and their children sampled from the Danish National Birth Cohort.

METHODS

Participants were sampled based on maternal alcohol consumption before pregnancy. At 5 years of age, the children were tested with the Wechsler Preschool and Primary Scale of Intelligence-Revised, the Test of Everyday Attention for Children at Five (TEACh-5), and the Movement Assessment Battery for Children (MABC). The Behaviour Rating Inventory of Executive Function (BRIEF) was completed by the mothers and a preschool teacher. Parental education, maternal IQ, prenatal maternal smoking, child's age at testing, child's sex, and maternal alcohol intake during pregnancy were considered potential confounders.

MAIN OUTCOME MEASURES

Performance on the Wechsler Preschool and Primary Scale of Intelligence-Revised, the TEACh-5, the MABC, and the BRIEF.

RESULTS

Intake of 15-21 drinks/week on average prior to pregnancy was not associated with any of the outcomes, but intake of ≥22 drinks/week on average was associated with a significantly lower adjusted mean full scale IQ and lower adjusted means in overall attention and sustained attention score, but not in selective attention score or any of the BRIEF index scores or MABC scores.

CONCLUSIONS

Intake of ≥22 drinks/week before pregnancy was associated with lower mean full scale IQ, overall attention and sustained attention. Assessment of pre-pregnancy drinking provides additional information regarding potential prenatal alcohol exposure and its implications for child neurodevelopment.

Comparison of growth factor treatments on the fibrochondrogenic potential of canine fibroblast-like synoviocytes for meniscal tissue engineering

OBJECTIVE

To determine the in vitro effects of differing growth factor treatments on the fibrochondrogenic potential of fibroblast-like synoviocytes from cruciate ligament deficient femorotibial joints of dogs.

STUDY DESIGN

In vitro study.

SAMPLE POPULATION

Synoviocytes from dogs (n = 8) with naturally occurring cruciate ligament insufficiency.

METHODS

Synoviocytes were cultured in monolayer and synthesized into tensioned synoviocyte bioscaffolds (TSB) suspended in media containing TGF-β3, or FGF-2, TGF-β1, and IGF-I. The 1,9-dimethylmethylene blue (DMMB) assay and toluidine blue stain assessed glycosaminoglycan content; hydroxyproline assay, and collagen I and II immunohistochemistry assessed collagen content. Biomechanical properties were determined by materials testing/force-deformation curves.

RESULTS

All tissue cultures formed tensioned fibrous tissue-like constructs. Mean tissue cellularity and cellular viability was significantly greater in the triple growth factor-treated TSB by 0.09% and 44%, respectively. Percentage collagen content, and relative gene expression for collagen I, II, and aggrecan was not significantly different between groups. Median percentage of GAG content was significantly greater in triple growth factor-treated TSB by 1.6%. Biomechanical properties were not different in compression. Triple growth factor-treated TSB were significantly stronger in toughness, peak load to failure, and stiffness in tension.

CONCLUSIONS

TGF-β3 cultured bioscaffolds failed to outperform triple growth factor-treated TSB. Architectural extracellular matrix (ECM) organization and cellularity likely explained the differences between groups. TGF-β3 alone cannot be recommended at this time for in vitro formation of autologous fibrocartilage bioscaffolds for meniscal deficiency.

Differential cellular zinc levels in metastatic and primary nasopharyngeal carcinoma

Zinc levels are known to be elevated in certain cancer tissues. In this study, zinc content in metastatic and primary nasopharyngeal carcinoma (NPC) cells were quantitated by X-ray microanalysis at the ultrastructural level. Zinc levels of cancer cells derived from the cervical lymph node of a patient with metastatic carcinoma and that from the nasopharynx biopsy of another NPC patient with no clinical evidence of secondary spread, were analyzed. X-ray microanalysis revealed significantly higher cellular zinc levels in metastatic NPC cells. Zinc is a known anti-apoptotic agent and tumor response to radiotherapy is linked with apoptosis or programmed cell death. Raised zinc levels observed here could provide the biological basis for the observation of a higher percentage of distant metastasis in cervical node positive NPC patients treated by radiotherapy (the mainstay of treatment for NPC) as compared to those without regional nodal disease.

Relationship of donor variables and graft dimension on biomechanical performance of femoral ring allograft

Structural femoral ring allograft is commonly used in interbody spinal arthrodesis. Fractures of implanted femoral ring allograft have been reported. Data to guide donor screening and tissue processing by allograft tissue banks for factors that affect graft strength are incomplete. Fresh frozen human femora from 34 cadaveric donors were sectioned into ten 20-mm thick specimens. Bone mineral density (BMD), donor age, and graft dimensions were recorded for each specimen. Three hundred twenty-seven specimens were tested in quasi-static axial compression. Linear regression models compared load to failure with BMD, sex-specific donor age, minimum/maximum cortical wall thickness, and minimum/maximum outer ring diameter. Correlations between minimum and maximum cortical wall thickness and load to failure were significant (r = 0.73, p < 0.001 and r = 0.74, p < 0.001, respectively). BMD showed a weaker negative correlation with load to failure (r = -0.11, p = 0.05). Correlations between load to failure and minimum and maximum outer ring diameter and age (r = 0.06, p = 0.31) were not significant. We found that the minimum and maximum cortical wall thicknesses of femoral ring allograft are strongly correlated with the axial compressive load to failure of the graft. Other tested parameters did not prove to be effective predictors of resistance to axial loading.

Biomechanical comparison of a fully threaded, variable pitch screw and a partially threaded lag screw for internal fixation of Type II dens fractures

STUDY DESIGN

Stiffness and load to failure were studied in a human cadaver model of Type II odontoid fractures stabilized with either a single partially threaded lag screw and washer or a headless fully threaded variable pitch screw.

OBJECTIVE

To determine whether a headless fully threaded variable pitch screw provides biomechanically superior fixation of Type II odontoid fractures in comparison with a partially threaded, cannulated lag screw and washer.

SUMMARY OF BACKGROUND DATA

Surgical treatment of Anderson and D'Alonzo Type II odontoid fractures is often performed using a partially threaded cannulated screw and washer. Reported clinical failure rates of this construct are as high as 20%. This technique requires perforation of the cortex of the tip of the dens, placing the brainstem and vertebrobasilar circulation at risk. A headless fully threaded variable pitch screw has not been described for this application.

METHODS

A transverse osteotomy was created at the base of the dens in 16 human cadaver C2 specimens and stabilized using either a headless fully threaded variable pitch screw or a partially threaded cannulated lag screw and washer. Specimens were loaded to failure under a static, posteriorly directed force applied to the surface of the dens. Stiffness and load to failure were measured and the mode of failure for each specimen was determined.

RESULTS

Stiffness and load to failure were greater for the headless, fully threaded variable pitch screw compared with the partially threaded lag screw and washer. The mode of failure for all specimens was via anterior screw cut-out at the C2 vertebral body.

CONCLUSION

A headless, fully threaded variable pitch screw was biomechanically favorable in comparison with a partially threaded lag screw and washer in this cadaver model of Type II dens fractures. The mode of failure at the C2 vertebral body may have important implications for further improvements in construct strength.

Application of high-energy synchrotron radiation for texture studies

A novel experimental technique that employs high-energy synchrotron radiation is used for the investigation of through-thickness texture gradients in two aluminium plates, cold-rolled 40% with either intermediate or small draughts. In these two plates, crystallographic textures are inspected in a large number of layers. Texture maps of pole densities throughout the sample thickness are presented. A texture of the rolling type is developed through the plate thickness after intermediate draught rolling. Pronounced inhomogeneities associated with the shear texture are observed in the sample rolled with small draughts. For selected layers, direct pole figures are compared with those obtained by traditional low-energy X-ray diffraction and by the electron backscattering pattern technique using a scanning electron microscope. A good qualitative agreement between textures measured using the three different techniques is obtained. Experimental aspects and potentials of the new technique are discussed.

Immunohistochemical expression of p53 protein in invasive breast carcinoma: clinicopathologic correlations

The results of immunohistochemical expression of p53 protein in 106 invasive breast cancers were correlated with conventional pathologic prognostic parameters. Archival formalin-fixed, paraffin-embedded tissue sections of these cases were stained with a monoclonal antibody (Ab-2), raised against p53 protein using a peroxidase-labelled streptavidin biotin kit. Fifty-six (53%) showed positive nuclear staining; 31 were considered weakly, 21 moderately and 4 strongly positive. Forty-three (77%) of these positive cases stained less than 50% of the tumor cells, with a significant association between intensity and proportion of nuclei stained (p<0. 05). p53 staining also correlated with histologic grade (p<0.005) but not with tumor size nor clinical stage (p>0.05). The follow-up data did not reveal any statistically significant survival advantage for patients with p53 negative tumors.

Biomechanical evaluation of impaction fractures of the femoral head

OBJECTIVES

To measure the effect of an impaction fracture of the femoral head on load transmission in the hip joint.

DESIGN

We measured the contact areas and pressure between the acetabulum and femoral head of cadaveric pelves in four different conditions: intact, with an operatively created one-square-centimeter defect in the superior femoral head, with a two-square-centimeter defect, and with a four-square-centimeter defect. All defects were uniformly three millimeters deep.

SETTING

Hips were loaded in a simulated single-limb stance. Pressure and area measurements were made with Fuji pressure-sensitive film.

SPECIMENS

Seven hip joints in seven whole pelves were tested.

MAIN OUTCOME MEASUREMENTS

Contact area, load, and mean and maximum pressures were measured.

RESULTS

Peripheral loading was seen in the intact acetabulum. This was not disrupted after impaction fractures of any size. A significant increase in mean maximum pressures in the superior acetabulum was seen with two-square-centimeter and four-square-centimeter defects.

CONCLUSIONS

In contrast to prior biomechanical studies of acetabular fractures, our investigation revealed that disruption of the peripheral distribution of load does not occur with impaction fractures of the femoral head. Clinical series indicate that impaction injuries to the femoral head are associated with a poor prognosis. Previous biomechanical data on acetabular fracture patterns associated with a poor prognosis have shown increases in mean and peak pressures in the superior acetabulum. This was seen with two-square-centimeter and four-square-centimeter impaction injuries. Other factors, such as wear of the articular cartilage during joint motion or associated microscopic damage to the remainder of the joint surface at the time of injury, may also contribute to the rapid joint deterioration seen in these injuries. Further study is indicated.

Metallothionein expression and zinc levels in invasive ductal breast carcinoma

Metallothioneins (MTs) and zinc are both known to promote progression of tumors in human cancers. A close relationship exists between MT and zinc, as synthesis of the former has been reported to be induced by the latter. To assess the relationship between MT and zinc content in breast cancer tissues, we analysed MT expression by immunohistochemistry and tissue zinc levels by atomic absorption spectrometry (AAS) in invasive ductal breast cancers and adjacent benign breast tissues. We observed overexpression of MT in breast cancer tissues and noted that zinc content in breast cancer tissues was twice that of benign breast tissues. The nuclear fraction obtained by subcellular fractionation of breast cancer tissues was found to have a higher zinc content than the plasma membrane and cytosolic fractions. Contrary to expectations, we found a significant inverse correlation of MT expression with zinc levels in breast cancer tissues, suggesting that whilst both synergistically influence growth and survival of tumor cells, they may also have divergent roles in carcinogenesis.

The role of the acetabular labrum and the transverse acetabular ligament in load transmission in the hip

We performed a biomechanical study of seventeen hip joints in the pelves of nine cadavera in order to assess the role that the acetabular labrum and the transverse acetabular ligament play in load transmission. The distribution of contact area and pressure between the acetabulum and the femoral head was measured with the hip in four different conditions: intact (seventeen hips), after removal of the transverse acetabular ligament (eight hips), after removal of the entire labrum (nine hips), and after removal of both the transverse acetabular ligament and the labrum (seventeen hips). The hip joint was loaded in simulated single-limb stance, and the measurements were made with use of pressure-sensitive film. A peripheral distribution of load was seen in the intact acetabula. This pattern was altered only minimally after removal of the transverse acetabular ligament or the labrum, or both. When both of these structures were removed, the only significant change was a decrease in the maximum pressure in the posterior aspect of the acetabulum (p = 0.02). No significant changes were detected with regard to the contact area, load, mean pressure, or maximum pressure in the anterior or superior aspect of the acetabulum under any testing condition.

Biomechanical evaluation of a low anterior wall fracture: correlation with the CT subchondral arc

OBJECTIVE

To measure the effect of a simulated low anterior wall fracture of the acetabulum on load transmission in the hip joint.

DESIGN

We measured the contact areas and pressure between the acetabulum and the femoral head of cadaveric pelves in three different conditions: intact, with an operatively created fracture of the anterior wall, and after anatomic reduction and internal fixation of the fracture.

SETTING

Hips were loaded in simulated single-limb stance. Pressure and area measurements were made with Fuji pressure-sensitive film.

SPECIMENS

Seven hip joints in seven whole pelves were tested.

INTERVENTION

Anterior wall fractures were anatomically reduced and fixed.

MAIN OUTCOME MEASUREMENTS

Contact area, load, and mean and maximum pressures were measured.

RESULTS

Anterior wall fractures in our specimens entered the hip joint an average of 9.7 millimeters from the vertex of the acetabulum, corresponding to a 45-degree roof arc measurement. Peripheral loading seen in the intact acetabulum was disrupted after fracture. The loading pattern was not restored to preinjury levels with anatomic reduction and fixation. There was no significant change in the contact area (p = 0.43), force (p = 0.06), or mean (p = 0.57) or maximum (p = 0.20) pressures in the superior aspect of the acetabulum after creation of the anterior wall fracture.

CONCLUSIONS

These results differ from those of previous studies with posterior wall acetabulum fractures, where significant increases in force and mean and maximum pressures were noted in the superior acetabulum after fracture. The lack of significant increases in superior acetabular pressures is discussed in relation to the mean computed tomographic subchondral arc of approximately ten millimeters in our specimens.

Bone ingrowth and mechanical properties of coralline hydroxyapatite 1 yr after implantation

A previous study of coralline hydroxyapatite as a bone-graft substitute was extended from 4 to 12 months to determine better the relationships between implantation time, bone ingrowth and mechanical properties. The model consisted of a 10 x 30 mm window defect in the shaft of the canine radius (a cortical site), and a 10 mm diameter cylindrical defect in the head of the humerus (a cancellous site). In the new study, these two defects were made bilaterally in eight dogs, and filled with block-form coralline hydroxyapatite. The radius defects were supported by a metal fixation plate which was removed after 9 months. After 12 months, the dogs were killed and the left-side implants were analyzed histomorphometrically and mechanically. The right-side radius and humerus were reserved for structural analysis. The results were combined with those previously measured after 4, 8, 12 and 16 wk of implantation. In the cortical site, bone ingrowth increased from 52% at 16 wk to 74% at 1 yr. In the cancellous site, bone ingrowth was 38% after 4 wk, then fell monotonically, reaching 17% at 1 yr. Bending and compressive strength and stiffness of the radius implants increased throughout the post-implantation year, but compressive strength and stiffness of the humerus implants did not change after the first 2-4 months. Mechanical properties were strongly correlated to bone ingrowth in the cortical, but not the cancellous, site. The volume fraction of the coralline hydroxyapatite material diminished significantly with time in the cortical, but not the cancellous, site.