Uncemented hip revision cup as an alternative for T-type acetabular fractures: A cadaveric study

BACKGROUND

The current rise in elderly patients with compromised bone quality complicates the surgical treatment of acetabular T-type fractures (AO type 62B2 fractures). There is on ongoing discussion about the treatment options, mostly consisting of an open reduction and internal fixation (ORIF) with or without primary or secondary total hip arthroplasty (THA). Yet, these patients are oftentimes unable to fulfil weight-bearing restrictions and mostly present with an unavailability of a stable anchor site. Consequently, this study investigates the feasibility of a cementless hip revision cup for acetabular T-type fractures and compares its biomechanical properties to ORIF.

HYPOTHESIS

The cementless hip revision cup provides sufficient biomechanical stability under the simulation of full weight-bearing.

PATIENTS AND METHODS

The study compared two groups of human cadaveric hip bones with T-type fractures, of whom 6 subjects were treated with ORIF (6 male; mean age: 62±17years; mean body weight: 75±15) versus 6 subjects treated with a cementless hip revision cup (2 male; 69±12 years; 73±15kg). The group-assignment was controlled for comparable BMD results (mean BMD: ORIF 110±37 mg Ca-Ha/mL versus hip revision cup 134±32 mg Ca-Ha/mL). To compare for biomechanical stability cyclic loading was applied measuring the force and dislocation of the fracture gap at standardized bone loci using an all-electric testing machine and a 3D-ultrasound measuring system.

RESULTS

Comparing superior pubic ramus versus iliac wing (cementless hip revision cup versus ORIF [mean±standard deviation]: 5.8±2.0 versus 7.0±3.2; p=0.032) as well as sacral ala versus iliac wing (4.6±2.2 versus 6.4±3.7; p=0.002), the cementless revision cup achieved a significantly higher stability than the plate osteosynthesis.

CONCLUSION

Revision cup and ORIF withstood biomechanical loading forces exceeding full weight-bearing in this biomechanical study. The results of our study suggest that the cementless hip revision cup might be promising alternative to the current standard care of ORIF with or without primary THA.

LEVEL OF EVIDENCE

III; case control experimental study.

Evaluation of a New Treatment Strategy for Geriatric Fragility Fractures of the Posterior Pelvic Ring Using Sensor-Supported Insoles: A Proof-of-Concept Study

The incidence of fragility fractures of the pelvis (FFPs) is currently rising. Surgical treatment, which is performed using sacroiliac screws, is complicated by compromised bone quality, oftentimes resulting in implant failure. The iFuse implant system aims to improve attachment and durability with promising results for sacroiliac dysfunction, though data for its feasibility on FFPs are rare. Consequently, this study aims to evaluate the feasibility of the iFuse for FFPs. A total of 10 patients with FFPs were treated with the iFuse in this study. Pre- and postoperatively, both mobility using an established insole force sensor for an inpatient gait analysis and general well-being and pain using questionnaires were evaluated. When comparing pre- and postoperative findings, this study demonstrated a significant increase in the average (8.14%) and maximum (9.4%) loading (p < 0.001), a reduction in pain, as measured by the visual analog scale (VAS), from 4.60 to 2.80 at rest (p = 0.011) and from 7.00 to 4.40 during movement (p = 0.008), an increase in the Barthel Index by 20 points (p < 0.001) and an increase in the Parker Mobility Score by 2.00 points (p = 0.011). All this contributes to the possibility of early postoperative mobilization and improved general well-being, ultimately preventing the late consequences of postoperative immobilization and maintaining patients autonomy and contentment.

Descriptive analysis and short-term follow-up clinical results of osteochondral lesions of the distal tibia based on data of the German Cartilage Register (Knorpelregister® DGOU)

INTRODUCTION

An increasing number of ankle injuries with osteochondral lesions (OCL) also include lesions of the distal tibia. Therefore, the German Cartilage Society database is used to describe and examine the characteristics of these lesions and, early on, the results of different surgical therapies on the clinical outcome.

MATERIALS AND METHODS

Forty-seven patients out of 844 registered in the German Cartilage Society database met the inclusion criteria showing an OCL of the distal tibia (OLDT). Sixteen of them also presented a 1-year follow-up regarding the Foot and Ankle Ability Measure (FAAM). Further evaluations were included in the follow-up, such as the Foot and Ankle Outcome Score (FAOS) and the Visual Analogue Scale for pain (VAS).

RESULTS

The patients' mean age was 35 ± 11 with a mean BMI in the range of overweight (26/27 ± 5 kg/m²). The lesions were equally distributed on the articular surface of the distal tibia. Most patients were operated using anterior ankle arthroscopy [n_T 34 (72%); n_S 13 (81%)], while some (n_T 9; n_S 4) converted to open procedures. Almost 90% staged III and IV in the ICRS classification. Debridement, bone marrow stimulation, solid scaffolds, and liquid filler were the treatment choices among the subgroup. All therapies led to a clinical improvement between pre-op and 1-year follow-up but not to a significant level.

CONCLUSION

This study presents baseline data of OLDT based on data from a large database. BMS and scaffolds were the treatment of choice but did not present significant improvement after a 1-year follow-up.

Improving stability of atlantoaxial fusion: a biomechanical study

PURPOSE

The incidence of atlanto-axial injuries is continuously increasing and often requires surgical treatment. Recently, Harati developed a new procedure combining polyaxial transarticular screws with polyaxial atlas massae lateralis screws via a rod system with promising clinical results, yet biomechanical data is lacking. This biomechanical study consequently aims to evaluate the properties of the Harati technique.

METHODS

Two groups, each consisting of 7 cervical vertebral segments (C1/2), were formed and provided with a dens axis type 2 fracture according to Alonzo. One group was treated with the Harms and the other with the Harati technique. The specimen was loaded via a lever arm to simulate extension, flexion, lateral flexion and rotation. For statistical analysis, dislocation (°) was measured and compared.

RESULTS

For extension and flexion, the Harati technique displayed a mean dislocation of 4.12° ± 2.36° and the Harms technique of 8.48° ± 1.49° (p < 0.01). For lateral flexion, the dislocation was 0.57° ± 0.30° for the Harati and 1.19° ± 0.25° for the Harms group (p < 0.01). The mean dislocation for rotation was 1.09° ± 0.48° for the Harati and 2.10° ± 0.31° for the Harms group (p < 0.01). No implant failure occurred.

CONCLUSION

This study found a significant increase in biomechanical stability of the Harati technique when compared to the technique by Harms et al. Consequently, this novel technique can be regarded as a promising alternative for the treatment of atlanto-axial instabilities.

Blunt traumatic thoracic aortic injuries: a retrospective cohort analysis of 2 decades of experience

OBJECTIVES

The aim of this study was to analyse and report the changes in the management of blunt traumatic aortic injuries (BTAIs) in a single centre during the last 2 decades.

METHODS

A retrospective analysis of all patients diagnosed with BTAI from January 1999 to January 2020 was performed. Data were collected from electronic/digitalized medical history records.

RESULTS

Forty-six patients were included [median age 42.4 years (16-84 years), 71.7% males]. The predominant cause of BTAI was car accidents (54.5%, n = 24) and all patients presented with concomitant injuries (93% bone fractures, 77.8% abdominal and 62.2% pelvic injuries). Over 70% presented grade III or IV BTAI. Urgent repair was performed in 73.8% of patients (n = 31), with a median of 2.75 h between admission and repair. Thoracic endovascular repair (TEVAR) was performed in 87% (n = 49), open surgery (OS) in 10.9% (n = 5) and conservative management in 2.1% (n = 1). Technical success was 82.6% (92.1% TEVAR, 79% OS). In-hospital mortality was 19.5% (17.5% TEVAR, 40% OS). Of these, 3 died from aortic-related causes. Seven (15.2%) required an early vascular reintervention. The median follow-up was 34 months (1-220 months), with 19% of early survivors having a follow-up of >10 years. Only 1 vascular reintervention was necessary during follow-up: secondary TEVAR due to acute graft thrombosis. Of the patients who survived the initial event, 6.7% died during follow-up, none from aortic-related causes.

CONCLUSIONS

Even with all the described shortcomings, in our experience TEVAR for BTAI proved to be feasible and effective, with few complications and stable aortic reconstruction at mid-term follow-up. With the current technical expertise and wide availability of a variety of devices, it should be pursued as a first-line therapy in these challenging scenarios.

Cementless hip revision cup for the primary fixation of osteoporotic acetabular fractures in geriatric patients

BACKGROUND

Elderly patients suffering from hip fractures are usually not able to fulfil postoperative weight-bearing restrictions. Therefore, the operative fixation construct has to be as stable as possible. Aim of the present study was to determine (1) whether a therapeutic advantage could be achieved when using hip arthroplasty to treat acetabular fractures in geriatric patients; (2) whether an acetabular revision cup would be suitable for achieving fast postoperative mobilization and full weight-bearing; and (3) when a treatment with an uncemented hip revision cup for the primary fixation of osteoporotic acetabular fractures in geriatric patients is indicated.

MATERIALS AND METHODS

The functional outcome of THA using a reconstruction cup for an acetabular fracture was evaluated in ten patients using standardized scoring instruments. In addition, an analysis of the preexisting literature referring to total hip replacement in geriatric acetabular fractures was conducted and an algorithm for standardizing the treatment approach for geriatric patients with acetabular fractures was developed.

RESULTS

The mean EQ-5D-3L quality of life score 0.7. The mean VAS Score was 58.2. The average Barthel Index was 80.0 points [range: 0-100]. The mean HHS was 72.0 points, while the MHH Score yielded an average of 63.4 points. The average AP Score was 7.5. The literature analysis showed that total hip arthroplasty could be a feasible option for geriatric acetabular fractures.

CONCLUSION

Primary hip arthroplasty using uncemented revision cup fixed with angular stable screws showed good results and is a feasible treatment option of acetabular fractures in geriatric patients. The approach is especially beneficial in patients with poor bone stock and allows postoperative full weight-bearing. The presented treatment algorithm could be a useful tool for identifying the most appropriate treatment option.

LEVEL OF EVIDENCE

IIb.

Resomer C212© in vertebroplasty or kyphoplasty: A feasibility study on artificial bones with biomechanical and thermal evaluation

BACKGROUND

Vertebroplasty and kyphoplasty are now well-established methods for treating compression fractures of vertebral bodies (AO type A) as well as vertebral body metastases [1, 2, 3]. However, polymethylmethacrylate (PMMA) augmented vertebrae show fractures of subsequent vertebral bodies due to the increased stability of the augmented vertebral body [4]. Resorbable cements are currently only used experimentally. Many commercially available resorbable calcium phosphate cements do not exhibit sufficient biomechanical stability to treat vertebral body fractures [5]. Resomer C212© (Evonik Industries AG, Essen, Germany) is a slow resorbable poly-ε-caprolactone that has low melting temperatures and good biomechanical properties.

OBJECTIVE

This is a feasibility study on how the poly-ε-caprolactone Resomer C212© can be used for kypho- or vertebroplasty, what temperatures are used in the argumentation and how differences in load capacity are measurable compared to conventional PMMA cement.

METHODS

23 Sawbones© blocks (7.5 Open Cell Foam, SKU: 1522-09, laminated on both sides, 4 × 4 × 2.9 cm, Sawbones, Vashon Island, USA) were divided into three groups: 7 without augmentation, 8 augmented with PMMA cement Traumacem V+© (DePuy Synthes, West Chester, USA) and 8 augmented with Resomer C212©. Temperature measurements were made in a 37∘C water bath centrally in the block and on the top and bottom plates. This was followed by a maximum load of up to 2000 N using a universal testing machine (Instron E 10000, Instron Industrial Products, Grove City, USA).

RESULTS

In the Resomer C212© test group, the maximum average increase in temperature was 4.15 ± 4.72∘C central, 0.3 ± 0.31∘C at the top and 0.78 ± 1.27∘C at the base. In the cement test group, the average increase in temperature was 9.80 ± 10.65∘C centrally in the test block, 1.50 ± 0.73∘C at the top plate and 1.42 ± 0.66∘C and the base plate. In the axial compression test, the 7 non-kyphoplasted test blocks showed a first loading peak on average at 275.23 ± 80.98 N, a rigidity of 238.47 ± 71.01 N/mm2. In the Traumacem V+© group, the mean peak load was 313.72 ± 46.26 N and rigidity was 353.45 ± 77.23 N/mm2. The Resomer C212© group achieved a peak load of 311.74 ± 52.05 N and a stiffness of 311.30 ± 126.63 N/mm2. A compression to 50% could not be seen in any test block under the load of 2000 N. At 2000 N, Traumacem V+©'s average height reduction was 9.26 ± 2.16 mm and Resomer C212© was 10.93 ± 0.81 mm.

CONCLUSIONS

It has been shown that the application of Resomer C212© in kyphoplasty or vertebroplasty is well feasible. Thermal analysis showed significantly lower temperatures and shorter temperature application in the Resomer C212© group. In the biomechanical load up to 2000 N no significant differences could be observed between the individual groups.

SAT-523 The Use of FRAX in Identifying Women Less Than 65 Years Needing Bone Mineral Density Testing

The United States Preventive Service Task Force (USPSTF) recommends bone mineral density (BMD) screening for osteoporosis in women under the age of 65 by dual-energy x-ray absorptiometry (DXA) if their risk of a major osteoporotic fracture (MOF) is greater or equal to that of an average 65-year-old woman without risk factors for osteoporosis.(1) The absolute risk of a MOF is calculated using the FRAX ®, a tool that incorporates various risk factors to calculate risk with or without the addition of BMD of the femoral neck as a variable. Those, without the BMD variable, having a calculated 10-year risk of a MOF of 9.3% or greater are recommended for BMD testing. A retrospective chart review was completed for patients between 2012 to 2018. We identified 128 charts and analyzed the extracted data for 113 women < 65-years with osteoporosis confirmed by BMD or fractures. MOF fracture risk calculation without BMD by FRAX of 9.3% or greater were found in 51 (45.1%) patients. Osteoporosis by T-score <-2.5 at the spine, total hip, femoral neck or distal radius was evident in 102 (90%) patients. Previous osteoporotic fractures were noted in 29 (25.7%) patients. Demographics were stratified in terms of high-risk (FRAX >= 9.3%) and low-risk (FRAX< 9.3%). The average age of women in the high-risk group was 58 years and 55 years in the low-risk group. In the high-risk group, 88.2% were Caucasian, 11.8% Hispanic, 0% African American, 0% Asian. In the low risk group, 59.7% were Caucasian, 32.3% Hispanic, 3.2% African American, 4.8% Asian. Women with MOF >9.3% were older, had more years post menopause, and had more risk factors (average 2.18 factors vs 0.61) than women with MOF <9.3%. Total hip T-score was lower in the high-risk group. The sensitivity of FRAX for identifying women with a T-score < -2.5 was 40%. The sensitivity of FRAX for identifying women with a history of fracture was 32%. The sensitivity of FRAX for identifying women with a T-score < -2.5 or identifying women with a history of fracture was 32%. These results demonstrate that the FRAX tool alone, according to USPSTF recommendation, fails to identify many women under the age of 65 with osteoporosis in need of BMD testing. Over half of women would not have had a BMD performed based on guidelines for screening BMD in women < 65. Further study is needed to characterize women under the age of 65 with osteoporosis with FRAX MOF less than 9.3%. Reference: 1. U.S. Preventive Services Task Force (2011). Screening for osteoporosis: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2011;154:356-64. Research Support: Grant to support statistical analysis from the University of Texas Health San Antonio School of Medicine Office of the Dean.

MON-196 Gender-Affirming Hormonal Therapy and Incidence of Metabolic Syndrome and Cardiovascular Events in Patients with Gender Dysphoria

Background: Long-term effects of gender-affirming hormonal therapy (GAHT) on cardiovascular risk factors and metabolic syndrome (MS) is currently unclear. Particularly, the effect of GAHT on cardiovascular outcomes in older individuals (>60 years) with gender dysphoria (GD) is unknown. The aim of this study was to examine the effect of GAHT on cardiovascular risk factors, MS and the incidence of T2DM in subjects with GD. Methods: We reviewed the records of 75 subjects with GD, 54 transwomen (age 49 ± 2 years) and 21 transmen (age 37 ± 2 years), who had a detailed clinical, biochemical and hormonal profile (lipid profile, HbA_1C, FPG, testosterone, estradiol) of which 55 were followed for at least 1 year. MS was defined based on ATP III criteria. As a control group, we reviewed the records of 30 subjects without GD who attended the endocrinology clinic for other hormone-related disorders. Results: The median (IR) follow-up was 22 (11-39) months for transwomen and 15 (11-21) months for transmen. In transwomen plasma testosterone levels decreased (379 ± 31 vs 71 ± 18 ng/dL), estradiol increased (40 ± 7 vs 124 ± 34 pg/mL) while the plasma testosterone levels increased in transmen (57 ± 14 vs 411 ± 79 ng/dL). At baseline, 24% of transwomen had MS and after 1 year, 16% of subjects had MS. In transmen, the prevalence of MS was similar before and 1 year after treatment (25 % vs. 24%). In transwomen, GAHT was associated with mild weight gain, BMI increased (29 ± 1 vs. 30 ± 1 kg/m², p=0.04). There was no difference in HDL, total cholesterol and triglyceride levels before and after hormone therapy, though LDL cholesterol tended to decrease (101 ± 6 vs. 90 ± 6 mg/dL, p=0.06). There was no change in HbA_1C, FPG or SBP in transwomen, though DBP decreased (77 ± 1 vs. 74 ± 1 mmHg, p=0.05). In transmen, no changes were observed in BMI, HDL, total cholesterol, triglycerides, LDL, HbA_1C, FPG and blood pressure. There were no new cases of T2DM, however 1 transman developed MS, 1 transman had CABG and 1 transwoman died from laryngeal cancer. There were no new cases of myocardial infarction or stroke in subjects with and without GD. For subjects above 60 years (n=16, 13 transwomen and 3 transmen), BMI in transwomen increased (27 ± 1 vs. 29 ± 2 kg/m², p=0.03), there was no change in HDL, LDL and total cholesterol, triglycerides, HbA_1C, FPG or blood pressure. In 3 transmen older than 60 years old, only the LDL decreased (194 ± 59 vs. 141 ± 55 mg/dL, p=0.006). In the entire group as well as older individuals with GD the incidence of CV events were not different from the control group. Conclusion: GAHT for 1.5 years was not associated with worsening cardiovascular risk factors, metabolic syndrome or incidence of T2DM in both transmen and transwomen regardless of their age. Long-term studies are required to assess the definite effects of GAHT on cardiovascular outcomes.

OR29-5 New Insights into the Genotype/Phenotype Profile of TMEM127 Germline Mutations

Abstract: Pheochromocytomas/paragangliomas (PHEOs/PGLs) are frequently heritable catecholamine-secreting, neuroendocrine tumors. More than 15 distinct genes cause PHEO/PGL predisposition, including the TMEM127 tumor suppressor gene, a transmembrane protein of unknown function. The clinical spectrum, disease severity and risk of other tumors has not been well established in TMEM127-associated disease. This information is critically important for risk assessment and follow up of probands and mutation-carrier relatives. Goal: The objective of this study is to identify clinical and genetic features of patients with germline TMEM127 mutations and begin to delineate genotype-phenotype associations of relevance for clinical and follow up surveillance. Methods: Demographic and clinical data, including tumor type and location, family history, age at diagnosis, plasma and/or urine catecholamine and/or metanephrine levels, and mutation status were obtained from medical records and/or literature of patients identified with TMEM127 gene nonsynonymous variants. Results: 97 index patients (28 males/50 females/19 unreported) were identified with a germline TMEM127 variant. The most common clinical presentation was PHEO (n=72, 74.2%), followed by PGL (n=6, 6.1%) and renal cell carcinoma (RCC n=5, 5.1%). In addition, three patients presented with both PHEO and PGL (3%), two of which were head and neck PGL, and three other patients had combined PHEO and RCC (3%). The median age at diagnosis was 43.8 years (range, 9 months to 80 years). Twenty-five patients had multicentric presentation, mostly due to bilateral pheochromocytoma (20/25 patients, 80%). Familial history of PHEO/PGL was present in 13 patients and five individuals developed metastatic PHEO. Of those with available biochemical data, tumors secreted predominantly epinephrine (n=14/26, 53.8%), although norepinephrine- (n=2) and dopamine- (n=1) secreting tumors were also detected, and one tumor was non-secreting. In total, 70 distinct variants were identified. Most had a single occurrence (n= 56/70 80%), but 14 variants were detected more than once (2-7 times). Most mutations led to a truncated product including indels, splice site or nonsense variants (56.3%), while 43.6.% were missense. Approximately half of the missense mutations occurred within transmembrane domains. Conclusion: The most common presentation of TMEM127-associated disease is a single PHEO in patients older than 40y, similar to sporadic disease, as previously suggested. However, the frequency of PGLs and malignant disease is higher, while penetrance is lower, than previously reported. This information will be relevant for clinical surveillance strategies for affected individuals and their high-risk relatives.

The potential role of the osteopontin-osteocalcin-osteoprotegerin triad in the pathogenesis of prediabetes in humans

AIMS

To examine the relationship between hormones involved in bone remodeling and glucose metabolism alterations in prediabetes.

METHODS

Individuals (n = 43) with NGT (BMI = 31.1 ± 1.1 kg/m²) and individuals (n = 79) with impaired glucose regulation (IGR) (BMI = 31.9 ± 1.2 kg/m²) including subjects with IFG, IGT, and IFG-IGT underwent OGTT and DXA. Osteopontin (OPN), osteocalcin (OCN), osteoprotegerin (OPG), and PTH levels were measured at fasting. Beta-cell function was calculated using C-peptide deconvolution. Dynamic indexes of insulin sensitivity were calculated from OGTT. A subgroup underwent to a euglycemic hyperinsulinemic clamp with 3-³H-glucose to estimate the endogenous glucose production (EGP) and insulin-mediated body glucose disposal (TGD/SSPI).

RESULTS

OPN was higher in IGR compared to NGT (5.3 ± 0.5 vs. 3.3 ± 0.2 μg/mL; p = 0.008) and in isolated IGT compared to IFG and IFG-IGT (6.3 ± 0.5 vs. 4.5 ± 0.3 and 5.4 ± 0.5 μg/mL; p = 0.02). OCN was similar in IFG and NGT but lower in IGT and IFG-IGT compared to NGT (7.2 ± 0.3 and 5.4 ± 0.2 vs. 8.3 ± 0.3 ng/mL; p < 0.01). OPN was positively correlated with HbA1c, fasting and 2 h plasma glucose and PTH. OCN was negatively correlated with body fat, 2 h plasma glucose, insulin and positively correlated with Stumvoll index. OPG correlated with TGD/SSPI (r = - 0.29; p < 0.05), EGP, and hepatic insulin resistance index in IGR (r = 0.51, r = 0.43; p < 0.01). There was no correlation between PTH and insulin sensitivity or Beta-cell function parameters.

CONCLUSIONS

In prediabetes, hormones known to be involved in bone remodeling may affect glucose metabolism before overt T2DM occurs with tissue-specific mechanisms.

Recurrent Mutations of Chromatin-Remodeling Genes and Kinase Receptors in Pheochromocytomas and Paragangliomas

PURPOSE

Pheochromocytomas and paragangliomas (PPGL) are genetically heterogeneous tumors of neural crest origin, but the molecular basis of most PPGLs is unknown.

EXPERIMENTAL DESIGN

We performed exome or transcriptome sequencing of 43 samples from 41 patients. A validation set of 136 PPGLs was used for amplicon-specific resequencing. In addition, a subset of these tumors was subjected to microarray-based transcription, protein expression, and histone methylation analysis by Western blotting or immunohistochemistry. In vitro analysis of mutants was performed in cell lines.

RESULTS

We detected mutations in chromatin-remodeling genes, including histone-methyltransferases, histone-demethylases, and histones in 11 samples from 8 patients (20%). In particular, we characterized a new cancer syndrome involving PPGLs and giant cell tumors of bone (GCT) caused by a postzygotic G34W mutation of the histone 3.3 gene, H3F3A Furthermore, mutations in kinase genes were detected in samples from 15 patients (37%). Among those, a novel germline kinase domain mutation of MERTK detected in a patient with PPGL and medullary thyroid carcinoma was found to activate signaling downstream of this receptor. Recurrent germline and somatic mutations were also detected in MET, including a familial case and sporadic PPGLs. Importantly, in each of these three genes, mutations were also detected in the validation group. In addition, a somatic oncogenic hotspot FGFR1 mutation was found in a sporadic tumor.

CONCLUSIONS

This study implicates chromatin-remodeling and kinase variants as frequent genetic events in PPGLs, many of which have no other known germline driver mutation. MERTK, MET, and H3F3A emerge as novel PPGL susceptibility genes. Clin Cancer Res; 22(9); 2301-10. ©2015 AACR.

Sclerostin and Insulin Resistance in Prediabetes: Evidence of a Cross Talk Between Bone and Glucose Metabolism

OBJECTIVE

A gene mutation of the Wnt/β-catenin signaling cascade is present in rare patients with the insulin resistance syndrome. Sclerostin is a circulating peptide inhibiting Wnt/β-catenin signaling. Our aims were to evaluate serum sclerostin in subjects with prediabetes and to analyze its relationship with insulin resistance and β-cell function.

RESEARCH DESIGN AND METHODS

We performed a cross-sectional study including 43 healthy normal glucose-tolerant (NGT) individuals and 79 individuals with impaired glucose regulation (IGR), which included subjects with impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and combined IFG-IGT, undergoing oral glucose tolerance test (OGTT) and dual-energy X-ray absorptiometry. A subgroup of 18 with NGT and 30 with IGR also underwent a euglycemic-hyperinsulinemic clamp with tracer.

RESULTS

Sclerostin levels were higher in IGR compared with NGT (50.8 ± 2.4 vs. 38.7 ± 2.3 pmol/L; P = 0.01), positively correlated with HOMA-insulin resistance (IR) (r = 0.62; P < 0.001), and negatively correlated with insulin-mediated total body glucose disposal (r = -0.40; P < 0.001). Fasting endogenous glucose production (EGP) and hepatic and adipose tissue insulin resistance indexes were positively correlated with sclerostin levels (r = 0.48, r = 0.62, and r = 0.61, respectively; P < 0.001). Fasting and OGTT insulin clearance were inversely correlated with sclerostin serum levels (r = -0.52 and r = -0.44, respectively; both P < 0.001). Sclerostin levels were not correlated with β-cell function parameters. In multiple linear regression analysis, the addition of sclerostin levels to the traditional risk factors for insulin resistance improved the r(2) associated with HOMA-IR (r(2) change: 0.055; F change: 28.893; P = 0.001) and insulin-mediated total body glucose disposal (r(2) change: 0.059; F change: 4.938; P = 0.033).

CONCLUSIONS

Sclerostin levels are increased in individuals with prediabetes and correlated with insulin resistance in skeletal muscle, liver, and adipose tissue. The correlation between sclerostin and insulin clearance at fasting state and during OGTT is novel; thus, studies are needed to explore the potential causal relationship.

First genome-wide association scan on neurophysiological endophenotypes points to trans-regulation effects on SLC2A3 in dyslexic children

Dyslexia is one of the most common learning disorders affecting about 5% of all school-aged children. It has been shown that event-related potential measurements reveal differences between dyslexic children and age-matched controls. This holds particularly true for mismatch negativity (MMN), which reflects automatic speech deviance processing and is altered in dyslexic children. We performed a whole-genome association analysis in 200 dyslexic children, focusing on MMN measurements. We identified rs4234898, a marker located on chromosome 4q32.1, to be significantly associated with the late MMN component. This association could be replicated in an independent second sample of 186 dyslexic children, reaching genome-wide significance in the combined sample (P = 5.14e-08). We also found an association between the late MMN component and a two-marker haplotype of rs4234898 and rs11100040, one of its neighboring single nucleotide polymorphisms (SNPs). In the combined sample, this marker combination withstands correction for multiple testing (P = 6.71e-08). Both SNPs lie in a region devoid of any protein-coding genes; however, they both show significant association with mRNA-expression levels of SLC2A3 on chromosome 12, the predominant facilitative glucose transporter in neurons. Our results suggest a possible trans-regulation effect on SLC2A3, which might lead to glucose deficits in dyslexic children and could explain their attenuated MMN in passive listening tasks.

A common variant in fibroblast growth factor binding protein 1 (FGFBP1) is associated with bone mineral density and influences gene expression in vitro

We previously detected strong evidence for linkage of forearm bone mineral density (BMD) to chromosome 4p (lod=4.3) in a set of 29 large Mexican American families. Fibroblast growth factor binding protein 1 (FGFBP1) is a strong candidate gene for bone homeostasis in this region. We sequenced the coding region of FGFBP1 in a subset of our Mexican American study population and performed association studies with BMD on SNPs genotyped in the entire cohort. We then attempted to replicate these findings in an independent study cohort and performed in vitro functional studies on replicated, potentially functional polymorphisms using a luciferase reporter construct to evaluate influence on gene expression. Several SNPs spanning the gene, all in one large block of linkage disequilibrium, were significantly associated with BMD at various skeletal sites (n=872, p=0.001-0.04). The associations were then replicated in an independent population of European ancestry (n=972; p=0.02-0.04). Sex-stratified association analyses in both study populations suggest this association is much stronger in men. Subsequent luciferase reporter gene assays revealed marked differences in FGFBP1 expression among the three common haplotypes. Further experiments revealed that a promoter polymorphism, rs12503796, results in decreased expression of FGFBP1 and inhibits upregulation of the gene by testosterone in vitro. Collectively, these findings suggest that sequence variation in FGFBP1 may contribute to variation in BMD, possibly influencing osteoporosis risk.

Serum MEPE-ASARM-peptides are elevated in X-linked rickets (HYP): implications for phosphaturia and rickets

MEPE (Matrix Extracellular PhosphoglycoprotEin) expression is markedly elevated in X-linked-hypophosphatemic-rickets (HYP) and tumor-induced osteomalacia (TIO). In normal individuals, circulating serum-levels of MEPE are tightly correlated with serum-phosphorus, parathyroid hormone (PTH) and bone mineral density (BMD). Also, MEPE derived, C-terminal ASARM-peptides are candidate minhibins and/or phosphatonins. Our aims were to determine: 1. whether MEPE-ASARM-peptide(s) are abnormally elevated in HYP/hyp serum, and, 2. whether the ASARM-peptide(s) accumulate in hyp mice kidney renal-tubules. Using a specific competitive ELISA we measured a five fold increase (P=0.007) of serum ASARM-peptide(s) in human HYP patients (normal subjects 3.25 microM n=9; S.E.M.=0.51 and HYP-patients 15.74 microM, n=9; S.E.M.=3.32). A 6.23 fold increase (P=0.008) was measured in hyp male mice compared with their normal male siblings (normal-siblings, 3.73 muM, S.E.M.=0.57, n=3; and hyp-mice 23.4 microM, n=3, S.E.M.=4.01). Renal immuno-histological screening also revealed a dramatic increase of ASARM-peptides in regions anatomically consistent with the proximal convoluted tubules. This study demonstrates for the first time that markedly elevated serum levels of protease-resistant ASARM-peptide(s) occur in HYP/hyp and they accumulate in murine hyp kidneys. These peptides are thus likely responsible for the phosphaturia and defective mineralization in HYP/hyp and TIO.

Muscle stem cells can act as antigen-presenting cells: implication for gene therapy

Research has shown that the use of a muscle-specific promoter can reduce immune response and improve gene transfer to muscle fibers. We investigated the efficiency of direct and ex vivo gene transfer to the skeletal muscles of 6- to 8-week-old mdx mice by using two adenoviral vectors: adenovirus (AD) encoding the luciferase gene under the cytomegalovirus (CMV) promoter (ADCMV) and AD encoding the same gene under the muscle creatine kinase (MCK) promoter (ADMCK). Direct intramuscular injection of ADMCK triggered a lower immune response that enabled more efficient delivery and more persistent expression of the transgene than did ADCMV injection. Similarly, ex vivo gene transfer using ADCMV-transduced muscle-derived stem cells (MDSCs) induced a stronger immune response and led to shorter transgene expression than did ex vivo gene transfer using ADMCK-transduced MDSCs. This immune response was due to the release of the antigen after MDSC death or to the ADCMV-transduced MDSCs acting as antigen-presenting cells (APCs) by expressing the transgene and rapidly initiating an immune response against subsequent viral inoculation. The use of a muscle-specific promoter that restricts transgene expression to differentiated muscle cells could prevent MDSCs from becoming APCs, and thereby could improve the efficiency of ex vivo gene transfer to skeletal muscle.

Herpesvirus saimiri vFLIP provides an antiapoptotic function but is not essential for viral replication, transformation, or pathogenicity

Apoptosis of infected cells is an important host defense mechanism, and many viruses have exploited antiapoptotic proteins that interfere with crucial cellular pathways. Viral FLICE inhibitory proteins (vFLIPs) are encoded by rhadinoviruses like herpesvirus saimiri, the related Kaposi's sarcoma-associated herpesvirus-human herpesvirus 8 (KSHV/HHV8), and the poxvirus responsible for molluscum contagiosum. The vFLIPs can block the interaction of the death receptor-adapter complex with the cellular effector FLICE (caspase-8), and this prevents the initiation of the downstream caspase cascade. KSHV/HHV8 vFLIP overexpression can confer resistance to T-cell-mediated apoptosis and acts as a tumor progression factor in a murine B-cell lymphoma model. To analyze the function of herpesvirus vFLIPs in the genetic background of the virus and in a model for viral pathogenesis, we deleted the vFLIP gene (open reading frame 71) from the genome of herpesvirus saimiri strain C488. The viral deletion mutant was viable and replicated like the wild-type virus. An antiapoptotic effect could be attributed to the vFLIP gene, but we also show that the vFLIP gene of herpesvirus saimiri is dispensable for viral transformation of T cells in vitro and for pathogenicity in cottontop tamarins in vivo.

[Pain and psychological disorders in the elderly]

This paper points to different physiological diseases which are associated with extreme pain. Extreme and chronic pain can be related to a higher risk of suicide. Special patterns of pain are characterized psychologically. Furthermore, the relationship between pain and depression is discussed. The necessity for psychosomatic concepts in diagnosis and treatment of pain is shown. Special forms of experiencing pain in patients who suffer from dementia are described. These patients appear to have difficulties in perceiving and describing (clinical) pain.

RelA is a potent transcriptional activator of the CD28 response element within the interleukin 2 promoter

T-cell activation requires two different signals. The T-cell receptor's recognition of a specific antigen on antigen-presenting cells provides one, and the second signal comes from costimulatory molecules such as CD28. In contrast, T cells that are stimulated with antigen in the absence of the CD28 costimulatory signal can become anergic (nonresponsive). The CD28 response element (CD28RE) has been identified as the DNA element mediating interleukin 2 (IL-2) gene activation by CD28 costimulation. Our previous work demonstrates that the Rel/NF-kappa B family proteins c-Rel, RelA (p65), and NFKB1 (p50) are involved in the complex that binds to the CD28RE. We also showed that c-Rel, but not NFKB1 (p50), can bind to the CD28RE and activate CD28RE-driven transcription in cotransfection assays. However, the role of RelA (p65) in CD28 signaling has not yet been addressed. We provide evidence that RelA (p65) itself bound directly to the CD28RE of the IL-2 promoter and other lymphokine promoters. In addition, RelA (p65) was a potent transcriptional activator of the CD28RE in vivo. We show that a RelA (p65)-c-Rel heterodimer bound to the CD28RE and synergistically activated the CD28RE enhancer activity. We also demonstrate that activated Raf-1 kinase synergized with RelA (p65) in activating the CD28RE enhancer activity. Interestingly, a soluble anti-CD28 monoclonal antibody alone, in the absence of other stimuli, also synergized with RelA (p65) in activating the CD28RE. Furthermore, we show that RelA (p65) activated expression of the wild-type IL-2 promoter but not the CD28RE-mutated IL-2 promoter. A combination of RelA (p65) and NFKB1 (p50) also activated the IL-2 promoter through the CD28RE site. These results demonstrate the functional regulation of the CD28RE, within the IL-2 promoter, by Rel/NF-kappa B transcription factors.

A dominant negative Raf-1 mutant prevents v-Src-induced transformation

A vector expressing a dominant negative mutant of Raf-1 was stably introduced into BALB/c 3T3 cells expressing a temperature-sensitive derivative of v-Src. High levels of the Raf-mutant were detected in these cells. Expression of the Raf-1 mutant blocked v-Src-induced transformation, as determined by reversion to a flat non-transformed morphology and the inability to form colonies in soft agar. Cells transfected with the parental vector lacking the mutant Raf-1 could be transformed by v-Src. These data suggest that intracellular signals activated by v-Src that are mediated by Raf-1 are required for transformation by v-Src.

An inhibitory mutant of c-Raf-1 blocks v-Src-induced activation of the Egr-1 promoter

The protein-tyrosine kinase activity of v-Src leads to the transcriptional activation of the mitogen-responsive transcription factor Egr-1. c-Raf-1 is a serine/threonine protein kinase that has been implicated in the transduction of signals induced by mitogens. The involvement of c-Raf-1 in v-Src-induced Egr-1 expression was investigated using an inhibitory mutant of c-Raf-1. We report here that expression of a kinase-defective mutant of c-Raf-1 inhibits v-Src-induced activation of the Egr-1 promoter. This inhibition is reversed by overexpression of wild type c-Raf-1. Consistent with an involvement of c-Raf-1 in a signaling pathway leading to Egr-1 expression, we find that v-Raf induces Egr-1 promoter activation. These data suggest that c-Raf-1 is a component in an intracellular signaling pathway initiated by v-Src leading to the induction of the mitogen-responsive transcription factor Egr-1.

[How families deal with demented relatives--provisional results of an ongoing study (author's transl)]

In the course of a geriatric-sociological field-investigation 140 families were studied, which live with an old relative and take care of him in case of disease. 45 of the old persons suffered from a dementive syndrome of medium or severe degree. All the information obtained in these 45 families (precoded-interviews, questionnaires, free-interviews, follow-up contacts, group-work with care-taking relatives) was inspected regarding the question whether the families, when dealing with the diseased family-member, showed one or more of the following reactions: 1. Reactions of despair 2. Sympathy for the experience of decreasing efficiency 3. Dementia and neurotic interaction 4. Activating care 5. Pedagogic efforts 6. Inclusion of children 7. Readiness and avoidance of contact 8. Readiness to spoil the demented relative - The results show, that the relatives make altogether great efforts ehen caring for their demented family members; this refers to psychic energy as well as to material means.

[Family care for the aged in multigenerational households (author's transl)]

Multigenerational household with widowed elderly above the age of 70 have been studied by interviewing the aged person and his/her daughter/daughter in law. The sample is described according to household composure and some sociodemographic characteristics. Data analysis focused on the relationship between variables in the elderly person and variables in the daughter/daughter in law. Psychic and somatic well-being in the relatives can be predicted by the degree of competence/dependency in the aged family member, but less so with a general health assessment. Organic brain conditions in the aged parents seem to have most adverse effects on the daughter/daughter in law when they are of a moderate degree.

[Treatment of the sick elderly in households accommodating several generations]

Multigenerational households with widowed persons aged 70 and more have been studied in order to determine the relationship between the following two groups of variables: (a) variables in the aged person describing the existence and degree of an organic mental impairment due to a dementive process and of other signs of physical illnesses. (b) variables in her daughter or daughter in law consisting of selfratings of psychosomatic complaints and of attitude-scales. Results were as follows: (a) If there were indications of personality changes due to an organic brain syndrom the relatives had a lower degree of life-satisfaction and more frequently suffered from psychosomatic symptoms and interpersonal stress than those, whose old relatives showed an unaltered personality. (b) A great number of comparisons failed to show any statistical differences. Especially severe physical illness, organic brain syndrome and the need for physical care were not related to life satisfaction, psychosomatic complaints, stress due to emotional involvement and the attitude towards home-care. Our attempt to explain the missing correlations led to the following factors: the small size of the sample, self-selection of the sample and possibly inappropriate operationalisation and measurement of variables. In respect to these results the ongoing study will be modified in some details: There will be a qualitative analysis of transcribed semi-structured interviews. The proportion of families with severely demented relatives will be increased. In an additional step we shall examine families, who have decided to transfer their old member into an institution.