Rates of implantable cardioverter defibrillator implantation and outcomes in octogenarians or older compared to non-octogenarians in a statewide cohort from 2009 to 2018

Background

Octogenarians are underrepresented or excluded in major implantable cardioverter defibrillator (ICD) trials. The deployment of ICDs and their real-world outcomes in octogenarians is unclear.

Purpose

To investigate the prevalence and outcomes of ICD implantation in octogenarian or older vs non-octogenarian.

Methods

We extracted details of all ICD implanted statewide from 2009–2018 including patient's characteristics, in-hospital complications and mortality using the Centre-for-Health-Record-Linkage administrative datasets. Implantation rates were adjusted for the population size by sex, age-groups in decade and calendar-year. Analysis was stratified by age <80 vs ≥80yo.

Results

There were 9304 admissions (12.1% ≥80yo) for de novo ICD implantation (mean±SD implantation: 1163±122 cases per-annum). The mean age for ≥80 vs <80yo groups was 83.5±2.9yo vs 66.2±12.1yo respectively (overall cohort mean age 66.1±13.1yo). Total ICD implantations increased by 8.4±12.4% vs 1.8±8.4% per-annum for ≥80 vs <80yo groups. The mean implantation rates were 52.7±10.8 vs 22.0±2.8 per-100,000-persons in ≥80yo compared to <80yo, respectively, with rates increasing at 7.7±18.3% per-100,000-persons-per-annum in ≥80yo. In contrast, implantation rates declined slightly by 0.2±12.4% per-100,000-persons-per-annum in <80yo groups. There was a non-significant trend towards more in-hospital non-fatal complications in ≥80yo compared to <80yo (10.8% vs 9.0% respectively, p=0.054), with no difference in in-hospital mortality (0.6% vs 0.4% respectively, p=0.32). The 1-year mortality was 10.7% in ≥80yo compared to 4.7% in <80yo (p<0.001), and 2-year mortality was 20.2% vs 8.8% respectively (p<0.001). The 1-yr and 2-yr mortality hazard ratio for ≥80yo was 2.0 (95% confidence interval [CI] 1.6–2.5, p<0.001) and 2.2 (95% CI 1.8–2.5, p<0.001) respectively after adjusting for sex, year of implantation, referral source, indications for ICD, and comorbidities. Overall, the annual rates of total in-hospital non-fatal complications and mortality did not alter significantly during the study period.

Conclusion

Despite limited clinical trials data on efficacy of ICD use in octogenarians or older, implantation rate was more than double that of <80yo age-groups, with the implantation rate observed to be increasing in ≥80yo. There was no significant difference in in-hospital mortality between the two age-groups, however the 1-year and 2-year mortality rates were significantly higher in the ≥80yo.

Funding Acknowledgement

Type of funding sources: None.

Diabetic visceral neuropathy of gastroparesis: gastric mucosal innervation and clinical significance

BACKGROUND

The pathogenesis of diabetic gastroparesis due to visceral neuropathy involves multi-dimensional mechanisms with limited exploration of gastric mucosal innervation. This study aimed to quantitatively examine this topic and its relationship with gastroparesis symptoms and gastric emptying in diabetes.

METHODS

We prospectively enrolled 22 patients with type 2 diabetes and gastroparesis symptoms and 25 age- and gender-matched healthy controls for comparison. The assessments include (1) neuropathology with quantification of gastric mucosal innervation density (MID) on endoscopic biopsy, (2) clinical manifestations with questionnaire of gastroparesis cardinal symptom index (GCSI), and (3) functional tests of gastric emptying scintigraphy (GES).

RESULTS

In diabetic patients, stomach fullness, bloating, and feeling excessively full after meals constituted the most common GCSI symptoms. Seven (32%) diabetic patients had prolonged gastric emptying patterns. In diabetes, gastric MID was significantly lower in all examined parts compared with the controls: antrum (294.8±237.0 vs. 644.0±222.0mm/mm³ , p<0.001), body (292.2±239.0 vs. 652.6±260.9mm/mm³ , p<0.001), and fundus (238.0±109.1 vs. 657.2±332.8mm/mm³ , p<0.001). Gastric MID was negatively correlated with gastroparesis symptoms and total scores of GCSI (p<0.001). Furthermore, gastric MID in the fundus was negatively correlated with fasting glucose and HbA1c levels. Gastric emptying parameters, including T_1/2 and gastric retention, were prolonged in diabetes and gastric retention at 3h was correlated with fasting glucose level.

CONCLUSION

In diabetes, gastric MID was reduced and GES parameters were prolonged. Both were correlated with gastroparesis symptoms and glycemic control. These findings provide pathology and functional biomarkers for diabetic visceral neuropathy of gastroparesis and underlying pathophysiology.

[A case of atypical iris corneal endothelial syndrome]

Iridocorneal endothelial syndrome is a rare ophthalmic disease, most of which are unilateral and common in women. The rate of misdiagnosis and missed diagnosis is relatively high due to its various clinical manifestations. In this case, the patient presented uncontrollable high intraocular pressure, corneal edema leading to difficult observation of corneal endothelium morphology, and accompanied by a small amount of iris neovascularization. No clearly diagnosis was made before glaucoma surgery. Further examination was performed after corneal clearance, and the final diagnosis was iris corneal endothelial syndrome (Chandler syndrome).

Maladaptive motor cortical excitability and connectivity in polyneuropathy with neuropathic pain

BACKGROUND

Sensory symptoms, especially neuropathic pain, are common in polyneuropathy. Conventional diagnostic tools can evaluate structural or functional impairment of nerves but cannot reveal mechanisms of neuropathic pain. Changes in the brain after polyneuropathy may play roles in the genesis of neuropathic pain.

METHODS

This cross-sectional study investigated changes of cortical excitability within left primary motor cortex (M1) by measuring resting motor thresholds, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF), and afferent inhibition between polyneuropathy patients and controls, and investigated the correlates of these parameters with neuropathic pain and the M1 structural and functional connectivity assessed by diffusion tractography imaging and functional MRI.

RESULTS

Thirty-three painful and 15 non-painful neuropathic patients and 21 controls were enrolled. There were no differences in intraepidermal nerve fiber density, nerve conduction study, thermal thresholds, or autonomic functional tests between patients with and without neuropathic pain. Compared to controls, neuropathic patients exhibited similar resting motor thresholds or afferent inhibition, but attenuated SICI and augmented ICF, especially in painful patients. Changes of intracortical excitability in neuropathic patients were correlated with intensities of neuropathic pain, and different presentations of SICI and ICF were noted between patients with and without thermal paresthesia. Additionally, short latency afferent inhibition at interstimulus intervals of 20 ms was associated with structural connectivity of left M1 with brain areas associated with pain perception.

CONCLUSIONS

Maladaptive cortical excitability with altered structural connectivity in left M1 developed after peripheral nerve degeneration and was associated with neuropathic pain and sensory symptoms in polyneuropathy.

Skin nerve pathology: Biomarkers of premanifest and manifest amyloid neuropathy

OBJECTIVE

Small-fiber sensory and autonomic symptoms are early presentations of familial amyloid polyneuropathy (FAP) with transthyretin (TTR) mutations. This study aimed to explore the potential of skin nerve pathologies as early and disease-progression biomarkers and their relationship with skin amyloid deposits.

METHODS

Skin biopsies were performed in patients and carriers to measure intraepidermal nerve fiber (IENF) density, sweat gland innervation index of structural protein gene product 9.5 (SGII[PGP9.5]) and peptidergic vasoactive intestinal peptide (SGII[VIP]), and cutaneous amyloid index. These skin pathologies were analyzed with clinical disability assessed by FAP stage score (stage 0-4) and compared to neurophysiological and psychophysical tests.

RESULTS

There were 70 TTR-mutant subjects (22 carriers and 48 patients), and 66 cases were TTR-A97S. Skin nerve pathologies were distinct according to stage. In carriers, both skin denervation and peptidergic sudomotor denervation were evident: (1) IENF density was gradually reduced from stage 0 through 4, and (2) SGII(VIP) was markedly reduced from stage 1 to 2. In contrast, SGII(PGP9.5) was similar between carriers and controls, but it declined in patients from stage 2. Skin amyloids were absent in carriers and became detectable from stage 1. Cutaneous amyloid index was correlated with SGII(PGP9.5) and stage in a multivariate mixed-effect model. When all tests were compared, only IENF density, SGII(PGP9.5), and cutaneous amyloid index were correlated with stage, and IENF density had the highest abnormal rate in carriers.

INTERPRETATION

Biomarkers of sensory and sudomotor innervation exhibited a stage-dependent progression pattern, with sensory nerve degeneration as the early skin nerve pathology. Ann Neurol 2019;85:560-573.

miR-375 inhibits the proliferation and invasion of glioblastoma by regulating Wnt5a

The aberrant expression of microRNA-375 (miR-375) has been proved to be associated with carcinogenesis. However, the role of miR-375 in glioblastoma (GBM) remains unknown. The aim of this study was to investigate biological functions and its molecular mechanisms of miR-375 in GBM cells. In this study, real-time PCR results showed that the level of miR-375 expression in GBM tissues and GBM cell lines (U87 and U251) was decreased. Using MTT assay, Transwell migration and invasion assay, we demonstrated that miR-375 overexpression significantly suppress cell proliferation, cell migration and cell invasion capacity in U87 and U251 cells. However, downregulation of miR-375 had reverse effects on cell proliferation, migration and invasion. Targeting association analysis, dual luciferase assay, RT-PCR and western blot analysis results confirmed that miR-375 could target the 3'UTR of Wnt5a mRNA and regulated its protein expression. Further studies also find overexpression of Wnt5a could significantly reverse miR-375-mediated proliferation, migration and invasion on U87 and U251 cells. Therefore, we concluded that miR-375 inhibited the proliferation and invasion of GBM by regulating Wnt5a and might be a possible therapeutic agent for GBM.

Multiple variants in 5q31.1 are associated with systemic lupus erythematosus susceptibility and subphenotypes in the Han Chinese population

BACKGROUND

A previous study provided evidence for a genetic association between PPP2CA on 5q31.1 and systemic lupus erythematosus (SLE) across multi-ancestral cohorts, but failed to find significant evidence for an association in the Han Chinese population.

OBJECTIVES

To explore the association between this locus and SLE using data from our previously published genome-wide association study (GWAS).

METHODS

Single-nucleotide polymorphisms (SNPs) rs7726414 and rs244689 (near TCF7 and PPP2CA in 5q31.1) were selected as candidate independent associations from a large-scale study in a Han Chinese population consisting of 1047 cases and 1205 controls. Subsequently, 3509 cases and 8246 controls were genotyped in two further replication studies. We then investigated the SNPs' associations with SLE subphenotypes and gene expression in peripheral blood mononuclear cells.

RESULTS

Highly significant associations with SLE in the Han Chinese population were detected for SNPs rs7726414 and rs244689 by combining the genotype data from our previous GWAS and two independent replication cohorts. Further conditional analyses indicated that these two SNPs contribute to disease susceptibility independently. A significant association with SLE, age at diagnosis < 20 years, was found for rs7726414 (P = 0·001). The expression levels of TCF7 and PPP2CA messenger RNA in patients with SLE were significantly decreased compared with those in healthy controls.

CONCLUSIONS

This study found evidence for multiple associations with SLE in 5q31.1 at genome-wide levels of significance for the first time in a Han Chinese population, in a combined genotype dataset. These findings suggest that variants in the 5q31.1 locus not only provide novel insights into the genetic architecture of SLE, but also contribute to the complex subphenotypes of SLE.

Linkage analysis of SNPs in IGFBP-6 and its relation with the body sizes of pig

Insulin-like growth factor binding protein-6 (IGFBP-6) is a member of the IGFBP family, which is known to be a key factor in regulating the effect of insulin-like growth factor-2 (IGF-2) on the animal growth and development. Gene sequences of 3'-untranslated regions (UTR) and exon 4 of IGFBP-6 may influence the expression and proteolysis of IGFBP-6. In this study, 551 bp of the IGFBP-6 (including 257 bp of intron 3, exon 4, and 170 bp of 3' UTR) were sequenced and compared in the Bama and Tibetan mini-pigs, the Landrace and Large White pigs, and the Northeast wild boars. Six single nucleotide polymorphisms (SNPs) were detected in the IGFBP-6, in which T593C, T636C, and T745C were in intron 3, A67G was in exon 4, and G37A was in 3' UTR. T636C, T745C, and A67G were in linkage and formed four kinds of haplotypes, with CCT being the dominant haplotype in the mini-pigs; however, the haplotype block was not formed in the Landrace pigs and Large White pigs or the Northeast wild boars. Based on the above results, we concluded that the SNPs and haplotype of the IGFBP-6 may be related to the mini-size formation of the pig.

An RNAi-based screen reveals PLK1, CDK1 and NDC80 as potential therapeutic targets in malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive tumour originating in the thoracic mesothelium. Prognosis remains poor with 9- to 12-month median survival, and new targets for treatments are desperately needed.

METHODS

Utilising an RNA interference (RNAi)-based screen of 40 genes overexpressed in tumours, including genes involved in the control of cell cycle, DNA replication and repair, we investigated potential therapeutic targets for MPM. Following in vitro characterisation of the effects of target silencing on MPM cells, candidates were assessed in tumour samples from 154 patients.

RESULTS

Gene knockdown in MPM cell lines identified growth inhibition following knockdown of NDC80, CDK1 and PLK1. Target knockdown induced cell-cycle arrest and increased apoptosis. Using small-molecule inhibitors specific for these three proteins also led to growth inhibition of MPM cell lines, and Roscovitine (inhibitor of CDK1) sensitised cells to cisplatin. Protein expression was also measured in tumour samples, with markedly variable levels of CDK1 and PLK1 noted. PLK1 expression in over 10% of cells correlated significantly with a poor prognosis.

CONCLUSION

These results suggest that RNAi-based screening has utility in identifying new targets for MPM, and that inhibition of NDC80, CDK1 and PLK1 may hold promise for treatment of this disease.

Sol/gel transition of chitosan solutions

This work studies the occurrence of sol/gel transition and the gel rheology for chitosan solution under various conditions. Experiments were conducted in an oscillatory shear apparatus with small amplitude, using a Rheometrics SR-5 rheometer, with Couette and parallel plate geometries. The experimental results demonstrate that the sol/gel transition concentration and the elastic modulus (G') for CS gel decrease as the pH value and the molecular weight (Mw) increase. However, the sol/gel transition concentration and G' became independent of Mw when Mw exceeded a threshold. The higher ionization constant, Kp, is responsible for the higher sol/gel transition concentration in a formic acid solution than in an acetic acid solution with equivalent molar concentration. The elastic modulus G' of a CS gel increases with temperature, which relationship differs from that for many polysaccharides, and can be understood through classical rubber elastic theory. Finally, a gel whose concentration was barely above the sol/gel point exhibited aging, and its G' and G" declined rather than increase with time, accompanied by a reversal from the sol/gel state back to the sol state. This is an uncommon aging behavior for a polysaccharide and a detailed explanation is provided.

3D FEA of high-performance polyethylene fiber reinforced maxillary dentures

OBJECTIVE

This project studies the effect of high-performance polyethylene (HPPE) fibers on stress distributions in a maxillary denture and the influence of fiber position on improving denture performance.

METHODS

A denture was scanned with a 3D Advanced Topometric Sensor digitizing system. The measuring system converted the images into a 3D digital model. A 3D reverse engineering technology then produced a numerical model which was then refined with Rapidform software. The underlying mucosa and bone were constructed using a freeform system integrated with a PHANTOM haptic device. A fiber lamella reinforcement was incorporated into the denture at different positions (fitting side, mid-palatal plane, polished side) with SolidWorks software. Boundary conditions were constrained at the top of the basal bone while bite force of 230 N was applied to the posterior teeth on both sides. The denture models were analyzed with ABAQUS software.

RESULTS

Stress concentrations were found at the incisal notch and at the anterior and posterior palatal surfaces of the unreinforced denture. The incorporated reinforcement effectively reduced the stress concentrations at these surfaces. Placement of the fibers at polished side was the best position in reducing stress concentrations.

SIGNIFICANCE

3D FEM usefully provides a non-laboratory means to reveal the weak areas in the maxillary complete denture, and exhibit the effectiveness of HPPE reinforcement together with fiber positions on enhancement of denture strength.

Fibulin 1 is downregulated through promoter hypermethylation in gastric cancer

Tumour suppressor genes (TSGs) were frequently inactivated through promoter hypermethylation in gastric carcinoma as well as pre-malignant gastric lesions, suggesting that promoter hypermethylation can be used as a marker to define novel TSGs and also biomarkers for early detection of gastric cancer. In an effort to search for such genes aberrantly methylated in gastric cancer development, fibulin 1 (FBLN1) was found as a candidate TSG epigenetically downregulated in gastric cancer. FBLN1 expression was downregulated in all of gastric cancer cell lines used (100%, 7 out of 7) and the primary gastric carcinoma tissues (84%, 86 out of 102) and significantly restored after pharmacological demethylation. Hypermethylation of the FBLN1 promoter was frequently (71%, 5 out of 7) detected in gastric cancer cell lines and primary gastric carcinoma tissues. Ectopic expression of FBLN1 led to the growth inhibition of gastric cancer cells through the induction of apoptosis. In summary, FBLN1 was identified as a novel candidate TSG epigenetically downregulated in gastric cancer.

Frequent epigenetic inactivation of secreted frizzled-related protein 2 (SFRP2) by promoter methylation in human gastric cancer

The role of secreted frizzled-related protein (SFRP) genes in gastric cancer remains largely unknown. We determined the frequency and functional significance of SFRPs hypermethylation in human gastric cancer. The expression and methylation status of four SFRP members (SFRP1, 2, 4, and 5) in primary gastric cancer samples was screened. The biological effects of SFRP were analysed by flow cytometry, cell viability assay and in vivo tumour growth in nude mice. Among the four SFRPs, only SFRP2 was significantly downregulated in gastric cancer as compared to adjacent non-cancer samples (P<0.01). Promoter hypermethylation of SFRP2 was detected in 73.3% primary gastric cancer tissues, 37.5% of samples showing intestinal metaplasia and 20% adjacent normal gastric tissues. Bisulphite DNA sequencing confirmed the densely methylated SFRP2 promoter region. Demethylation treatment restored the expression of SFRP2 in gastric cancer cell lines. Forced expression of SFRP2 induced cell apoptosis, inhibited proliferation of gastric cancer cells and suppressed tumour growth in vivo. Moreover, methylated SFRP2 was detected in 66.7% of serum samples from cancer patients but not in normal controls. In conclusion, epigenetic inactivation of SFRP2 is a common and early event contributing to gastric carcinogenesis and may be a potential biomarker for gastric cancer.

Bisphosphonates induce apoptosis of stromal tumor cells in giant cell tumor of bone

Giant cell tumour of bone (GCT) is an aggressive primary neoplasm that results in the production of osteolytic lesions. Stromal cells, which form the main neoplastic component of this tumor, regulate the formation of osleoclast-like giant cells that are ultimately responsible for bone destruction. Bisphosphonates prevent bone resorption by inhibiting osteoclast activity and promoting osteoclast apoptosis, and they have been known to induce apoptosis of primary neoplastic cells such as those in breast and prostate cancers. We hypothesized that in bisphosphonates may induce apoptosis not only in osteoclast-like giant cells but also in neoplastic stromal cells of GCT both in vitro and in vivo. Twelve patients with GCT were treated with weekly injections of pamidronate for a period of 6 weeks prior to surgery. GCT specimens were collected at the time of biopsy and during definitive surgery. TUNEL assay was used to evaluate apoptotic DNA fragmentation in cells. In addition, twelve GCT primary cultures from these patients were treated with zoledronate, pamidronate, or alendronate for 48 hours at different doses (3, 30, or 150 microM) and subjected to apoptosis assay by flow cytometry following fluorescent Annexin-V labeling. The results showed that pamidronate significantly induced apoptosis in both osteoclast-like giant cells and stromal tumor cells, in vivo. All three bisphosphonates caused substantial apoptosis of stromal tumor cells in cultures. Zoledronate was the most potent reagent, resulting in an average cell death of 27.41% at 150 microM, followed by pamidronate (22.23%) and alendronate (15.3%). Our observations suggest that these drugs may be considered as potential adjuvants in the treatment of GCT.

Alendronate regulates cell invasion and MMP-2 secretion in human osteosarcoma cell lines

BACKGROUND

Osteosarcoma is the most common malignant bone tumor of childhood. Significant proportions of these patients eventually develop pulmonary metastases and succumb to their disease even after conventional multi-agent chemotherapy and surgical excision. Matrix metalloproteinase (MMP)-2 induced degradation of blood vessel basement membranes is an important pre-requisite for tumor invasion and metastasis. Bisphosphonates (BPs) have been known to inhibit tumor growth and metastasis in some tumors such as breast cancer, renal cell carcinoma, and prostate cancer, and may do so through inhibition of MMP secretion. We, therefore, tested the effect of BPs on tumor cell invasion, MMP-2 secretion, and apoptosis of osteosarcoma cell lines.

PROCEDURE

Two osteosarcoma cell lines (SaOS-2, U(2)OS) were treated with alendronate (50, 100, and 150 microM) for 24 and 48 hr. Matrigel invasion assay was used to investigate the invasive potential of osteosarcoma cell lines before and after alendronate treatment. Real-time quantitative RT-PCR was used to determine the mRNA level of MMP-2 with and without alendronate treatment. Enzyme-linked immunosorbent assay (ELISA) was used to quantify the cytokine level of MMP-2 secreted in the condition medium. BP-induced cell apoptosis was evaluated by fluorescent flow cytometric analysis.

RESULTS AND CONCLUSIONS

The results showed that alendronate inhibited cell invasion of both osteosarcoma cell lines in a dose-dependent manner. Alendronate reduced the mRNA level and cellular level of MMP-2 in both cell lines in a time and dose-dependent manner. Alendronate also induced significant apoptosis in both cell lines. Our finding suggests that alendronate downregulates MMP-2 secretion and induces apoptosis in osteosarcoma cells, which may both contribute to the reduction of invasive potential of the tumor cells.

Expression of preosteoblast markers and Cbfa-1 and Osterix gene transcripts in stromal tumour cells of giant cell tumour of bone

In giant cell tumour of bone (GCT), mononuclear stromal cells, which represent the neoplastic component of this lesion, regulate the formation of multinucleated osteoclast-like giant cells which are the characteristic hallmark of this tumour. However, the origin of stromal tumour cells has not yet been clearly defined. In this study, we evaluated several osteoblast markers including collagen type I, bone sialoprotein (BSP), osteonectin and osteocalcin in GCT using immunohistochemical techniques. Amongst the 13 GCT specimens and 7 GCT stromal cell (GCTSC) cultures studied, majority of the GCTSC synthesized type I collagen, BSP and osteonectin proteins but did not produce the differentiated osteoblast marker, osteocalcin. We further examined the regulation of several important osteogenic genes such as Cbfa-1, osterix and osteocalcin, and regulation of ALP activity in GCTSC in culture by bone morphogenetic protein 2 (BMP-2). Real-time PCR analysis indicated that Cbfa-1, osterix and osteocalcin mRNA were present in primary cultures of GCTSC. The addition of BMP-2 upregulated Cbfa-1 and osterix gene expression within 12 h and the enhancement was still observed at 24 h. ALP activity was minimal in untreated GCTSC in cultures. The number of ALP-positive GCTSC was significantly increased following treatment with BMP-2 or combinations with beta-glycerophosphate and ascorbic acid. In contrast, BMP enhancement of osterix mRNA level and ALP activity was also seen in SaOS2 osteoblast-like cells, but not in the primary culture of normal human skin fibroblasts. In summary, our data suggest that GCT stromal tumour cells may have an osteoblastic lineage and retain the ability to differentiate into osteoblasts.

The effect of hyaluronan on osteoblast proliferation and differentiation in rat calvarial-derived cell cultures

Hyaluronan (or hyaluronic acid, HA) is an essential component of extracellular matrices. It interacts with other macromolecules and plays a predominant role in tissue morphogenesis, cell migration, differentiation, and adhesion. The cell signaling functions of HA are mediated through the CD-44 receptor and are dependent upon the molecular weight of the polymer. We hypothesized that an HA of appropriate molecular weight alone in optimal concentration may induce osteoblast differentiation and bone formation. Enzyme-digested calvarial-derived mesenchymal cells from 2-day-old newborn rats were cultured with the addition of HA of three different molecular weights (2300, 900, and 60 kDa). We added, 0.5, 1.0, and 2.0 mg/mL HA for each molecular weight to the medium at the first plating of cells. After 7 to 20 days in culture, cell proliferation and differentiation were evaluated by measuring thymidine incorporation, alkaline phosphatase activity, and osteocalcin gene expression. The effects of HA on bone formation were examined by using Alizarin red staining for mineralization. The results showed that low molecular weight HA (60 kDa) significantly stimulated cell growth, increased osteocalcin mRNA expression in a dose-dependent manner, but showed no apparent effects on alkaline phosphatase activity and bone mineralization. On the other hand, high-weight HA (900 and 2,300 kDa) significantly increased all the parameters examined, particularly alkaline phosphatase activity, in a dose-dependent manner and stimulated cell mineralization to 126% and 119% of the controls, respectively, in the 1.0 mg/mL dose. Our findings suggest that HA has a molecular weight-specific and dose-specific mode of action that may enhance the osteogenic and osteoinductive properties of bone graft materials and substitutes due to its stimulatory effects on osteoblasts.

Expression of VEGF and MMP-9 in giant cell tumor of bone and other osteolytic lesions

This study aims to investigate the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) in giant cell tumor of bone (GCT) and other osteolytic lesions in bone. By using semi-quantitative RT-PCR, we showed that three major isoforms of VEGF (121, 165 and 189) were expressed in GCTs, with isoform 121 being the most abundant. The expression levels of VEGF and MMP-9 mRNA were significantly higher in advanced GCTs (stage II/III) than in stage I GCTs. We further elucidated the cellular localization of VEGF and MMP-9 gene transcripts in GCT and other osteolytic lesions using an in situ hybridization assay. The results showed that stromal tumor cells and osteoclast-like giant cells of GCT, fibrous stromal cells in anuerysmal bone cysts and fibrous dysplasia, and Langerhans-type giant cells as well as histocytes in eosinophillic granuloma, were all strongly positive for VEGF and MMP-9 mRNA expression. In a prospective study, we performed VEGF and MMP-9 immuno-staining on paraffin sections of pathological tissues harvested from 48 patients (14 GCT, 10 anuerysmal bone cysts, 10 eosinophillic granuloma, 4 fibrous dysplasia, 2 simple bone cyst, 2 osteomyelitis and 6 patients with fractured femoral head as control). The results showed that the differences in VEGF and MMP-9 expression between Stage I and other advanced Stages (II, III and recurrent) were highly significant (p<0.001), with advanced stages showing a higher mean expression. The difference between recurrent and Stage II and III lesions, was also statistically significant (p=0.03 for VEGF, and p=0.01 for MMP-9 expression), with recurrent lesions showing a higher mean expression of both VEGF and MMP-9. In conclusion, VEGF and MMP-9 expression in osteolytic lesions of bone co-relates well with the extent of bone destruction and local recurrence. Their expression may therefore provide some prognostic indication of the possible aggressive behavior of the underlying pathology.

Receptor activator of NF-kappaB ligand (RANKL) is expressed in chondroblastoma: possible involvement in osteoclastic giant cell recruitment

AIMS

Chondroblastoma is a rare, locally aggressive bone tumour that causes osteolytic destruction at the epiphyseal end of the affected bone. It is possible that tumour cells may stimulate osteoclastogenesis and osteolytic destruction through the production of receptor activator of NF-kappaB ligand (RANKL), which is a key molecule essential for regulating osteoclast formation and activity. Therefore, the expression of RANKL at both the mRNA and the protein level was investigated in chondroblastoma tumour tissue obtained from patients.

METHODS

The expression of RANKL gene transcripts was analysed by the reverse transcription-polymerase chain reaction (RT-PCR), and the cellular localisation of RANKL mRNA and protein was demonstrated by means of in situ hybridisation and immunohistochemistry.

RESULTS

RT-PCR analysis indicated that RANKL mRNA was present in all chondroblastoma specimens and normal cancellous bone samples, but not in normal articular cartilage and chondrosarcoma tissues. In contrast, gene transcripts of osteoprotegerin (OPG), the decoy receptor of RANKL, were detected in all types of tissues. The chondroid origin of neoplastic mononuclear cells in chondroblastoma was confirmed by positive S-100 immunohistochemical staining. Both RANKL mRNA and protein were exclusively expressed in these neoplastic mononuclear cells.

CONCLUSIONS

These findings suggest that RANKL may be involved in the tumour cell induced recruitment of osteoclast-like cells and consequent osteolytic bone destruction in chondroblastoma.

Events in the mould during heat processing of poly(methyl methacrylate)

Recordings of temperature and pressure in the mould have raised questions concerning the flow of poly(methylmethacrylate) during heat processing. Three simple experiments investigated flow of polymerised and partly polymerised poly(methylmethacrylate). Flow was not observed at normal processing temperatures. These results, combined with the results of previous work, suggest that as the mould heats up, thermal expansion of the dough exceeds polymerisation contraction, causing increase in pressure rather than flow. Maximum pressure occurs at maximum temperature. Thereafter, thermal expansion is reduced, polymerisation contraction increases and pressure in the mould drops. When the lowest pressure is reached the poly(methylmethacrylate) is polymerised.