A randomized trial comparing balloon kyphoplasty and vertebroplasty for vertebral compression fractures due to osteoporosis.

BACKGROUND AND PURPOSE: Several trials have compared vertebral augmentation with nonsurgical treatment for vertebral compression fractures. This trial compares the efficacy and safety of balloon kyphoplasty and vertebroplasty. MATERIALS AND METHODS: Patients with osteoporosis with 1-3 acute fractures (T5-L5) were randomized and treated with kyphoplasty (n = 191) or vertebroplasty (n = 190) and were not blinded to the treatment assignment. Twelve- and 24-month subsequent radiographic fracture incidence was the primary end point. Due to low enrollment and early withdrawals, the study was terminated with 404/1234 (32.7%) patients enrolled. RESULTS: The average age of patients was 75.6 years (77.4% female). Mean procedure duration was longer for kyphoplasty (40.0 versus 31.8 minutes, P < .001). At 12 months, 7.8% fewer patients with kyphoplasty (50/140 versus 57/131) had subsequent radiographic fracture, and there were 8.6% fewer at 24 months (54/110 versus 64/111). The results were not statistically significant (P > .21). When we used time to event for new clinical fractures, kyphoplasty approached statistical significance in longer fracture-free survival (Wilcoxon, P = .0596). Similar pain and function improvements were observed. CT demonstrated lower cement extravasation for kyphoplasty (157/214 versus 164/201 levels treated, P = .047). For kyphoplasty versus vertebroplasty, common adverse events within 30 postoperative days were procedural pain (12/191, 9/190), back pain (14/191, 28/190), and new vertebral fractures (9/191, 17/190); similar 2-year occurrence of device-related cement embolism (1/191, 1/190), procedural pain (3/191, 3/190), back pain (2/191, 3/190), and new vertebral fracture (2/191, 2/190) was observed. CONCLUSIONS: Kyphoplasty and vertebroplasty had similar long-term improvement in pain and disability with similar safety profiles and few device-related complications. Procedure duration was shorter with vertebroplasty. Kyphoplasty had fewer cement leakages and a trend toward longer fracture-free survival.

The impact of different health dimensions on overall quality of life related to kyphoplasty and non-surgical management.

UNLABELLED: This study uses data from a previously published randomised trial where balloon kyphoplasty was compared to non-surgical management. Of the improved overall quality of life, 60 % was caused by decreased pain. However, ignoring other dimensions of quality of life would underestimate the procedure's effect. INTRODUCTION: Acute back pain has been viewed as the most important factor lowering quality of life (QoL) for patients suffering vertebral fractures. The objective of this study was to quantify the impact of different health dimensions on overall QoL using patient-reported outcome measurements (PROMs) collected in Fracture Reduction Evaluation (FREE) trial. METHODS: The analysis was based on patients included in the 2-year-long randomised controlled FREE trial studying the efficacy and safety of balloon kyphoplasty procedure (BKP) compared to non-surgical management (NSM). The PROMs included were EQ-5D, Short Form (SF)-36, visual analogue scale (VAS) pain and the Roland-Morris Disability Questionnaire (RMDQ). The health dimensional contribution to the overall QoL improvements was analysed by isolating the impact of each dimension on QoL in the SF-36 and EQ-5D, respectively. A correlation analysis of the QoL improvement was performed to investigate the relationships between the four instruments. RESULTS: Changes in pain explained 60 % of the quality-adjusted life years (QALY) gained in BKP vs. NSM followed by self-care (17 %), mobility (16 %) and usual activities (10 %) (EQ-5D). Health dimensions capturing the mental state had little impact on the QALY gained. The SF-36 dimensional analysis showed similar results. The correlation analysis showed that the correlation between VAS pain, RMDQ and QALY improvement was fairly weak. CONCLUSIONS: Changes in the pain dimension of health are the most important drivers for changes of overall QoL in patients treated with BKP or NSM. However, ignoring the impact of other dimensions would lead to an underestimation of the actual improvement in overall QoL.

A randomized trial comparing 2 techniques of balloon kyphoplasty and curette use for obtaining vertebral body height restoration and angular-deformity correction in vertebral compression fractures due to osteoporosis.

BACKGROUND AND PURPOSE: Vertebral compression fractures often result in pain and vertebral deformity. We compared 2 different balloon kyphoplasty techniques both using intraoperative curettage. MATERIALS AND METHODS: Adults 50 years of age or older with osteoporosis and 1 acute VCF were randomized to undergo bilateral BKP in which the curette was used first (n = 57) followed by inflatable bone tamps or in which IBTs were used first, followed by curettage and a second IBT inflation (n = 55). RESULTS: Mean procedure duration was 33.5 and 36.8 minutes, and fluoroscopy duration was 3.8 and 3.7 minutes for the CF and IBTF groups, respectively. Two-thirds of VCFs were wedge-shaped, and one-half had dynamic mobility. Anterior height restored postoperatively was 2.28 mm (95% CI, 1.49-3.08 mm; P < .001) and 2.78 mm (95% CI, 1.89-3.66 mm; P < .001) for CF and IBTF groups, representing ∼35% and 39% of lost height restored, but group differences were not significant (P = .4). Intraoperative anterior height gain attributed to dynamic mobility was 2.96 mm (95% CI, 1.92-4.00 mm; P < .001) and 3.05 mm (95% CI, 2.10-4.00 mm; P < .001); additional height attributed to IBT inflation was 1.09 mm (95% CI, 0.77-1.41 mm; P < .001) and 1.25 mm (95% CI, 0.68-1.82 mm; P < .001), representing a 37% and 41% increase. There was no significant height loss on IBT removal and cementation. Both groups had improved pain and ambulation. Asymptomatic leakage occurred in 15% of VCFs. There was 1 nonserious device-related hematoma (IBTF group). One new clinical VCF occurred in each group, but they were not device-related. CONCLUSIONS: Both techniques resulted in significant vertebral body height and pain improvement. Procedure and adverse event data demonstrated safe curette use in conjunction with balloon kyphoplasty procedures.

Chaperone-mediated regulation of hepatic protein secretion by caloric restriction.

Calorie restriction (CR) delays age-related physiological changes, reduces cancer incidence, and increases maximum life span in mammals. Here we show that CR decreased the expression of many hepatic molecular chaperones and concomitantly increased the rate and efficiency of serum protein secretion. Hepatocytes from calorie-restricted mice secreted twice as much albumin, 63% more alpha1-antitrypsin, and 250% more of the 31.5-kDa protein 2 h after their synthesis. A number of trivial explanations for these results, such as differential rates of protein synthesis and cell leakage during the assay, were eliminated. These novel results suggest that CR may promote the secretion of serum proteins, thereby promoting serum protein turnover. This may reduce the circulating level of damaging, glycoxidated serum proteins.

Vitamin D receptor displays DNA binding and transactivation as a heterodimer with the retinoid X receptor, but not with the thyroid hormone receptor.

The vitamin D receptor (VDR) is a transcription factor believed to function as a heterodimer with the retinoid X receptor (RXR). However, it was reported [Schräder et al., 1994] that, on putative vitamin D response elements (VDREs) within the rat 9k and mouse 28k calcium binding protein genes (rCaBP 9k and mCaBP 28k), VDR and thyroid hormone receptor (TR) form heterodimers that transactivate in response to both 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) and triiodothyronine (T(3)). We, therefore, examined associations of these receptors on the putative rCaBP 9k and mCaBP 28k VDREs, as well as on established VDREs from the rat osteocalcin (rOC) and mouse osteopontin (mOP) genes, plus the thyroid hormone response element (TRE) from the rat myosin heavy chain (rMHC) gene. In gel mobility shift assays, we found no evidence for VDR-TR heterodimer interaction with any tested element. Further, employing these hormone response elements linked to reporter genes in transfected cells, VDR and TR mediated responses to their cognate ligands only from the rOC/mOP and rMHC elements, respectively, while the CaBP elements were unresponsive to any combination of ligand(s). Utilizing the rOC and mOP VDREs, two distinct repressive actions of TR on VDR-mediated signaling were demonstrated: a T(3)-independent action, presumably via direct TR-RXR competition for DNA binding, and a T(3)-dependent repression, likely by diversion of limiting RXR from VDR-RXR toward the formation of TR-RXR heterodimers. The relative importance of these two mechanisms differed in a response element-specific manner. These results may provide a partial explanation for the observed association between hyperthyroidism and bone demineralization/osteoporosis.

Calories and aging alter gene expression for gluconeogenic, glycolytic, and nitrogen-metabolizing enzymes.

We characterized the effects of calorie restriction (CR) on the expression of key glycolytic, gluconeogenic, and nitrogen-metabolizing enzymes in mice. Of the gluconeogenic enzymes investigated, liver glucose-6-phosphatase mRNA increased 1.7- and 2. 3-fold in young and old CR mice. Phosphoenolpyruvate carboxykinase mRNA and activity increased 2.5- and 1.7-fold in old CR mice. Of the key glycolytic enzymes, pyruvate kinase mRNA and activity decreased approximately 60% in CR mice. Hepatic phosphofructokinase-1 and pyruvate dehydrogenase mRNA decreased 10-20% in CR mice. Of the genes that detoxify ammonia generated from protein catabolism, hepatic glutaminase, carbamyl phosphate synthase I, and tyrosine aminotransferase mRNAs increased 2.4-, 1.8-, and 1.8-fold with CR, respectively. Muscle glutamine synthetase mRNA increased 1.3- and 2. 1-fold in young and old CR mice. Hepatic glutamine synthetase mRNA and activity each decreased 38% in CR mice. These CR-induced changes are consistent with other studies suggesting that CR may decrease enzymatic capacity for glycolysis and increase the enzymatic capacity for hepatic gluconeogenesis and the disposal of byproducts of muscle protein catabolism.

Glucose regulation of GRP78 gene expression.

The endoplasmic reticulum chaperone glucose-regulated protein 78 (GRP78) is essential for the proper glycosylation, folding and assembly of many membrane bound and secreted proteins. GRP78 mRNA is well known to be induced in cultured cells by lowering medium glucose concentrations from 4.5 to 0 mg/ml. Here we report a study designed to determine the effects of intermediate concentrations of glucose on GRP78 mRNA abundance. Progressive reduction in culture medium glucose from 4.5 to 1.0 mg/ml progressively reduced GRP78 mRNA to approximately 30% of the initial level. Induction of GRP78 mRNA by glucose starvation was observed in medium containing less than 1 mg/ml glucose. Determination of the amount of glucose consumed in these cultures showed that reduction of glucose concentrations led first to repression of GRP78 mRNA abundance, followed by induction of the mRNA only when glucose is nearly exhausted. Caloric restriction in mice both reduces fasting and mean 24 h glucose blood concentrations and GRP78 mRNA abundance in the liver. Thus, it is possible that negative regulation of GRP78 mRNA in the liver is due directly to reduced blood glucose concentrations.

Caloric intake alters the efficiency of catalase mRNA translation in the liver of old female mice.

The free radical theory of aging predicts that calorie restriction, which extends life span, should reduce oxidant damage. In mammals, the oxidative processes centered in the liver are a major source of free radicals. Liver catalase has the dominant role in the intracellular detoxification of hydrogen peroxide. In male rodents, published studies indicate that aging decreases catalase gene transcription and that calorie restriction obviates this effect. In females, published studies are inconsistent, and no molecular mechanisms have been identified. Here we report that, in female mice, aging can lead to an increase in the translational efficiency of hepatic catalase mRNA, and that calorie restriction obviates this effect. Consideration of these results and published studies leads us to propose that the variability in catalase results in females may arise from the small number of studies or from unique aspects of female physiology, perhaps the estrous cycle and its cessation with age.

Dietary energy tissue-specifically regulates endoplasmic reticulum chaperone gene expression in the liver of mice.

A number of putative molecular chaperones seem to play essential roles in the correct folding, assembly and glycosylation of membrane and secreted proteins in the endoplasmic reticulum. We have shown that life span-extending dietary energy restriction significantly and specifically reduces GRP78 mRNA and protein by 50-75% in mice. Here, 5-mo-old female C3B10RF1 mice were given free access to food after being fed 50% less dietary energy since weaning. Hepatic GRP78 mRNA increased linearly, reaching the same level after 2 wk as was found in the liver of 20-mo-old mice with free access to food. This increase took place with no change in body weight. The mRNA levels of endoplasmic reticulum, cytosolic and mitochondrial chaperones were determined in young (7-mo-old) and old (21- or 28-mo-old) female C3B10RF1 mice. Each age group was either 50% energy restricted or was fed approximately 10% less energy than consumed by mice given free access to food. In young and old energy-restricted mice, hepatic expression of the endoplasmic reticulum chaperones ERp57 (37%), GRP170 (51%), ERp72 (43%), calreticulin (54%) and calnexin (23%) was significantly and specifically reduced. The GRP78, GRP94, GRP170, ERp57 and calnexin mRNA response to diet occurred reproducibly only in liver, and not in adipose, brain, heart, kidney, lung, muscle or small intestine. The mRNA for GRP75, a mitochondrial chaperone, HSC70, a cytoplasmic chaperone, protein disulfide isomerase, an endoplasmic reticulum chaperone, and C/EBPalpha, a transcription factor, was not regulated. Hepatic C/EBPbeta was 15% higher in old energy-restricted mice. Thus the expression of nearly all endoplasmic reticulum chaperones responded rapidly and specifically to dietary energy in mice.

Dietary energy restriction in mice negatively regulates hepatic glucose-regulated protein 78 (GRP78) expression at the posttranscriptional level.

Dietary energy restriction delays age-related physiologic changes, increases maximum life span, and reduces cancer incidence. We showed previously that 50% energy restriction in mice reduces hepatic expression of glucose-regulated protein mRNA by 50 to 80%. Changes in glucose-regulated protein 78 (GRP78) levels can either decrease or increase the rate of secretion of specific proteins. Therefore, energy restriction probably produces a global change in the spectrum of proteins secreted by the liver. These studies were initiated to investigate the molecular basis for the negative regulation of the gene. By use of transfection and nuclear run-on techniques, the strong induction of GRP78 gene transcription in cultured cells subjected to acute, extreme glucose deprivation has been well characterized. However, negative regulation of GRP78 gene expression in vivo by energy restriction is not as well understood. In our studies, a reduction in GRP78 protein levels determined using Western blotting closely paralleled a reduction in hepatic GRP78 mRNA measured by Northern and dot blotting. In each case the changes were statistically significant. This close correspondence indicates that energy restriction does not influence the translation rate or the stability of GRP78 protein. No statistically significant difference in the rate of transcription of the gene was detected in energy-restricted mice by use of transcription run-on assays. These results strongly suggest that energy restriction results in destabilization of GRP78 mRNA, thereby repressing hepatic expression of the gene.

Dietary calorie restriction in mice induces carbamyl phosphate synthetase I gene transcription tissue specifically.

Dietary calorie restriction (CR) delays age-related physiologic changes, increases maximum life span, and reduces cancer incidence. Here, we present the novel finding that chronic reduction of dietary calories by 50% without changing the intake of dietary protein induced the activity of mouse hepatic carbamyl phosphate synthetase I (CpsI) 5-fold. In liver, CpsI protein, mRNA, and gene transcription were each stimulated by approximately 3-fold. Thus, CR increased both the rate of gene transcription and the specific activity of the enzyme. Short-term feeding studies demonstrated that higher cpsI expression was due to CR and not consumption of more dietary protein. Intestinal CpsI activity was stimulated 2-fold, while its mRNA level did not change, suggesting enzyme activity or translation efficiency was stimulated. CpsI catalyzes the conversion of metabolic ammonia to carbamyl phosphate, the rate-limiting step in urea biosynthesis. cpsI induction suggests there is a shift in the metabolism of calorie-restricted animals toward protein catabolism. CpsI induction likely facilitates metabolic detoxification of ammonia, a strong neurotoxin. Enhanced protein turnover and metabolic detoxification may extend life span. Physiologic similarities between calorie-restricted and hibernating animals suggest the effects of CR may be part of a spectrum of adaptive responses that include hibernation.

Structure and regulation of the mouse GRP78 (BiP) promoter by glucose and calcium ionophore.

Dietary calorie restriction, also termed energy restriction, increases mean and maximum life span, reduces the incidence of tumors and increases the mean age of onset of diseases and tumors in every animal tested. Because life-span is genetically determined, we are studying the mechanisms by which energy restriction regulates the expression of genes. We found that energy restriction reduces hepatic glucose-regulated protein-78 (GRP78) and protein-94 mRNA levels by 2-3-fold in mice [Spindler et al., J. Nutr. 20 (1990) 1412-1417]. To investigate this down-regulation, we have cloned the mouse GRP78 promoter (pGRP78) and studied its regulation by glucose. The mouse pGRP78 and the previously cloned rat promoter mediate responsiveness to glucose deprivation, as well as to the calcium ionophore A23187. These studies are the first demonstration that cis-elements in the pGRP78 mediate responsiveness to glucose deprivation.

Homodimer and heterodimer DNA binding and transcriptional responsiveness to triiodothyronine (T3) and 9-cis-retinoic acid are determined by the number and order of high affinity half-sites in a T3 response element.

T3 (triiodothyronine) response elements (TREs) consist of pairs of strong and weak (S and W), 10-nucleotide T3 receptor (TR) monomer binding sites (half-sites). We report that the number and order of S and W half-sites in a direct repeat TRE determines whether it mediates ligand-dependent or independent transcriptional activation or inhibition in the presence of TR or TR and 9-cis-retinoic acid receptor (RXR); and whether a TRE is preferentially bound by TR homodimers, TR-RXR heterodimers, or CV1 cell TR accessory protein (TRAP)-TR heterodimers. TR homodimers bound equally to TREs composed of the 5'-S and 3'-W (SW) and the opposite (WS) arrangement of half-sites. TR-RXR gamma heterodimers bound SW better than WS. TR-TRAP heterodimers bound WS better than SW. Transcription of a reporter gene cis-linked to WS responded to unliganded TR and RXR, and either ligand stimulated expression 2-fold more. Reporter expression cis-linked to SW was not altered by unliganded receptors, and T3 stimulated transcription only in the presence of both TR and RXR. SS was strongly activated by liganded, but not by unliganded TR. SS was activated by unliganded TR and RXR gamma together, and T3 further stimulated transcription 2-fold. Under these conditions, transcription was inhibited 60% by 9-cis-retinoic acid.

Promoter independent down-regulation of the firefly luciferase gene by T3 and T3 receptor in CV1 cells.

We report that the activity of the firefly luciferase (LUC) reporter gene is down-regulated by T3 and T3 receptor (TR) in the CV1 mammalian cell line, which is widely used for studies of TR action. Repression was highly reproducible, T3 and TR dependent, promoter independent, and observed regardless of whether an internal control for transfection efficiency was used. Cotransfections with normal and mutant TRs indicate that the negative T3 response is mediated by sequences within the LUC gene coding region, and is not due to the interaction of TR with a limiting transcription factor. Negative regulation of the LUC reporter was overcome by a strong, cis-linked T3 response element (TRE), but continued in the presence of a TRE of moderate strength. The results described here demonstrate that conclusions drawn from studies of TRE structure and activity performed using the LUC reporter in CV1 cells should be interpreted with caution.

Positive and negative thyroid hormone response elements are composed of strong and weak half-sites 10 nucleotides in length.

The steroid-thyroid hormone receptors bind to imperfect repeats of two or more half-sites. It is generally accepted that a T3 response element (TRE) half-site consists of a six-nucleotide core motif (5'-AGGT(C/A)A-3'). It is less widely appreciated that the nucleotides flanking this core motif also have a major influence on the affinity of T3 receptor (TR) for its response element. We analyzed TR-DNA interactions under conditions in which the affinity of receptor monomers for individual TRE half-sites of the rat GH (rGH) gene was measured. These studies avoided the effects of half-site spacing and orientation on receptor binding. Variations in the nucleotides flanking the core sequence can modulate receptor binding by more than 15-fold. Systematic mutational analysis of TRE half-site structure demonstrated that at least two nucleotides flanking either side of the half-site core motif strongly influence TR binding affinity and activity, indicating that half-sites are approximately 10 nucleotides long. Thus, the half-sites of most TREs overlap, and mutations in one half-site may affect the activity of its partner. The TRE half-site sequence 5'-CTGAGGTAACG-3' was bound with highest affinity by TRs. The negatively T3-responsive promoter of the rGH gene was used to investigate the functional significance of the nucleotides flanking the core motif in vivo. A promoter consisting of only 22 rGH nucleotides, containing two functional TRE half-sites which overlap the rGH TATA box, directed T3-inhibited transcription. Mutation of nucleotides flanking the core sequence of the weaker half-site dramatically reduced the activity of the element, demonstrating that the flanking sequences of the half-sites can profoundly affect TRE activity.