Do patients report quality of life improvements after fitting of their unilateral bone conducting hearing implant?

OBJECTIVE: The audiological benefits of a bone conducting hearing implant are well documented; however, there is a paucity of literature comparing pre- and post-operative quality of life benefits. This study assessed the quality of life status before and after the device is implanted. METHODS: A prospective study was conducted of all adult bone conducting hearing implants inserted in a teaching hospital between 2012 and 2017. All patients completed the Glasgow Health Status Inventory, a validated quality of life questionnaire, before and three to six months after implantation. RESULTS: Sixty-two patients received a unilateral bone conducting hearing implant. All scores except the social score improved post-operatively. The paired t-test showed that the differences in the means for the Glasgow Health Status Inventory total, general and physical scores were statistically significant at the 5 per cent level (p < 0.0001). CONCLUSION: This study, one of the few to assess quality of life pre- and post-implantation, showed a vast improvement in patients' perceived quality of life from the pre- to the post-operative phase.

A 4-year retrospective study of tonsillectomy rate and admission rate of tonsillitis and complications in the East of England and nationally.

OBJECTIVES: Guidance set out by Scottish Intercollegiate Guidelines Network (SIGN) sought to restrict the frequency of elective tonsillectomy in reaction to the recognised and substantial risks of the procedure, namely pain and bleeding. With stricter criteria in place before a patient can undergo tonsillectomy, patients must endure more episodes of tonsillitis than was previously the case. The cost of managing tonsillitis and its complications as an inpatient is substantial to the NHS and also to the economy as a whole in missed work days. The authors sought to establish if the reduced rate of tonsillectomy performed had any effect on the rate of acute hospital admission for tonsillitis or the associated abscesses-peritonsillar, parapharyngeal and retropharyngeal. METHODS: A retrospective multi-centre study reviewed admission data across a 4-year period. The rate of tonsillectomies performed for recurrent tonsillitis across four trusts in Mid-Essex was compared with the number of admissions for tonsillitis, peritonsillar, parapharyngeal and retropharyngeal abscesses. National hospital episode statistics data over a 5-year period was also analysed. RESULTS: For the regional data in 2015, 979 tonsillectomies were performed across the four centres, reducing to 875 in 2018. There was no trend in the rates of acute tonsillitis requiring admission but the rates of peritonsillar abscess increased from 156 to 192 cases per year in the same period. This correlation was found not to be statistically significant in the measured sample size. The National hospital episode statistics data showed a significant correlation between tonsillectomy rates and admissions from complications of tonsillitis as well as the associated abscesses. CONCLUSION: This study shows that the reduced tonsillectomy rate was correlated with an increased number of admissions with peritonsillar abscess regionally. Nationally reduced tonsillectomy rate is significantly associated with increased admissions with tonsillitis and all its complications. A decreased rate of tonsillectomy may be increasing the rate of serious tonsillitis. This has an impact on patient morbidity, an increasing financial burden on the NHS and the UK economy.

Low dose effect of bisphosphonates on hMSCs osteogenic response to titanium surface in vitro.

Since the 1980s, titanium (Ti) implants have been routinely used to replace missing teeth. This success is mainly due to the good biocompatibility of Ti and the phenomenon of osseointegration, with very early events at implant placement being important in determining good osseointegration. However, enhancing implant performance with coatings such as hydroxyapatite (HA) and calcium phosphate has proved largely unsuccessful. Human mesenchymal stem cells (hMSCs) are the first osteogenic cells to colonise implant surfaces and offer a target for enhancing osseointegration. We previously reported that small doses of bisphosphonate (BP) may play an integral role in enhancing hMSC proliferation and osteogenic differentiation. The aim of this study is to investigate whether small doses of bisphosphonates enhance proliferation and osteogenic differentiation of hMSCs on Ti surfaces, to enhance bone osseointegration and to accelerate wound healing around the implant surface. Our data suggests that treating cells with small doses of BP (100 nM & 10 nM) induces significant hMSC stimulation of osteogenic markers including calcium, collagen type I and ALP compared to control group on titanium surfaces (P < 0.05). In addition, cell proliferation and migration were significantly enhanced on titanium surfaces (P < 0.05).

Management of pinna haematoma study (MaPHaeS): A multicentre retrospective observational study.

OBJECTIVES: To assess current variation in the management of pinna haematoma (PH) and its effect on outcomes. DESIGN: Multicentre retrospective observational record-based study. SETTING: Eleven hospitals around the UK. PARTICIPANTS: Eighty-three patients above the age of 16 with PH. OUTCOME MEASURES: The primary outcome measure was recurrence rate of PH over a 6-month period post-treatment, assessed by treatment type (scalpel incision vs needle aspiration). Secondary outcome measures assessed the impact of other factors on recurrence, infection and cosmetic complications of PH over a period of 6 months. RESULTS: After adjusting for confounding factors, involvement of the whole ear, and management within an operating theatre were associated with a lower rate of recurrence of pinna haematoma. The drainage technique, suspected aetiology, choice of post-drainage management, grade and specialty of practitioner performing drainage, the use of antibiotic cover and hospital admission did not affect the rate of haematoma recurrence, infection or cosmetic complications. CONCLUSIONS: Where possible PH should be drained in an operating theatre. Multicentre randomized controlled trials are required to further investigate the impact of drainage technique and post-drainage management on outcome.

Fatal cutaneous anthrax in a heroin user.

BACKGROUND AND OBJECTIVE: Cutaneous anthrax usually has a mortality rate of less than 1 per cent. However, since December 2009 there have been more than 13 deaths in the UK due to anthrax-contaminated heroin. We therefore wish to raise clinical awareness of this treatable disease. CASE REPORT: We describe the case of a heroin user with an equivocal presentation of cellulitis in the neck. Within 36 hours, this led to death due to cutaneous anthrax. CONCLUSION: Whilst cutaneous anthrax remains rare, this case report aims to raise awareness of the fact that the symptoms and signs of this condition in intravenous drug users may not always fit the typical picture.

Identification of RANKL in osteolytic lesions of the facial skeleton.

RANKL (receptor activator of nuclear factor kappaB ligand) promotes osteoclast differentiation, stimulates osteoclast activity, and prolongs osteoclast survival and adherence to bone. Abnormalities of the RANKL/RANK/osteoprotegerin system have been implicated in a range of diseases, including osteoporosis. To date, no work has been done in osteolytic lesions of the facial skeleton. In this study, specimens of ameloblastomas, dentigerous cysts, odontogenic keratocysts, and radicular cysts were subjected to immunohistochemical analysis for RANKL and tartrate-resistant acid phosphatase (TRAP). Immunofluorescence staining for TRAP was visualized under confocal microscopy. All specimens demonstrated distinct positive immunoreactivity to RANKL and TRAP. The TRAP-positive cells also stained with in situ hybridization for human calcitonin receptor, a definitive marker for osteoclasts. Mononuclear pre-osteoclasts were observed to migrate from blood to the connective tissue stroma and multinucleate toward the bone surface. It can be concluded that RANKL plays a role in bone resorption in osteolytic lesions of the facial skeleton.

Measurement of nitric oxide in temporomandibular joint saline aspirates.

Temporomandibular joint (TMJ) saline aspirates, obtained from the upper joint space of 17 patients undergoing TMJ arthroscopy under general anaesthesia were assayed for the presence of nitrite, a stable metabolite of nitric oxide by a spectrophotographic method using the Griess reaction. Measurable levels of nitrites were found in the saline aspirates of both symptomatic and asymptomatic joints. There was no statistically significant difference between the two sides. The presence of nitric oxide metabolites in the asymptomatic joints has not been previously reported in the literature. This finding may represent a latent disease process in the symptomless joint.

Human chaperonin 60 (Hsp60) stimulates bone resorption: structure/function relationships.

It is established that the molecular chaperone, chaperonin 60, from various bacteria and from Homo sapiens has cell-cell signalling activity and is able to induce proinflammatory cytokine synthesis. We previously reported that chaperonin 60 proteins from Gram-negative bacteria, but not mycobacteria, have the capacity to resorb cultured murine calvarial bone. We now report that lipopolysaccharide-low human recombinant chaperonin 60 (Hsp60) is a relatively weak cytokine-inducing agonist but is a potent stimulator of murine calvarial bone resorption. The osteolytic activity of Hsp60 was significantly inhibited by indomethacin, interleukin-1 receptor antagonist, and osteoprotegerin, but 5-lipoxygenase inhibitors were less effective. Analysis of Hsp60 truncation mutants revealed that N-terminal mutants (Delta1-137, Delta1-358, and Delta1-465) retained bone resorbing activity. In contrast, a C-terminal truncation mutant (Delta1-26 + Delta466-573) was inactive. This suggests that the active domain in this protein is found within residues 466-573. It is now established that Hsp60 is present in the blood of the majority of the population with the normal range encompassing levels able to activate bone cells. The possibility exists that this protein could play a role in bone remodelling.

Ultrasound stimulates nitric oxide and prostaglandin E2 production by human osteoblasts.

We have previously shown that the therapeutic range of ultrasound heals osteoradionecrotic bone and induces bone formation in vitro. It is well established that nitric oxide (NO) and prostaglandins are crucial early mediators in mechanically induced bone formation. The therapeutic range of ultrasound may act in the same way; therefore, we have investigated the effect of the therapeutic range of ultrasound on NO induction and prostaglandin E(2) (PGE(2)) production in vitro. Two ultrasound machines were evaluated, "traditional" (1 MHz, pulsed 1:4, tested at four intensities) and a "long-wave" (45 kHz, continuous, also tested at four intensities) devices. Ultrasound was applied to human mandibular osteoblasts for 5 min, and incubated at 37 degrees C for up to 24 h. The control group (sham insonated) was treated in the same way. NO was determined by measuring the nitrite concentration in the culture media colorimetrically, and PGE(2) was assayed by radioimmunoassay. Ultrasound produced a significant increase in both induced nitrite and PGE(2) production. The NO synthesis appeared to be via inducible NO synthase (iNOS) on the basis of the time course and levels of nitrite obtained, although the inhibition of other NOS isoforms by aminoguanidine cannot be excluded. PGE(2) synthesis appeared to be via COX-2. With the 45 kHz machine, a significant increase in NO was achieved at three intensities, 5, 30, and 50 mW/cm(2). The 1 MHz machine stimulated the synthesis of both NO and PGE(2), but was significant at only one dose (0.1 W/cm(2(SAPA))). There was no difference between the two machines with regard to PGE(2) synthesis. The time-course experiment revealed peak production to be 12-18 h for both NO and PGE(2). The therapeutic range of ultrasound stimulates both NO and PGE(2) synthesis by human osteoblasts, and the 45 kHz machine appeared to be more effective than the traditional short-wave length. These results may reflect the healing effect of ultrasound on fractures and osteoradionecrosis.

Temporomandibular joint synovial fluid sampling: estimation of dilution factor using calcium ion concentration.

Saline aspirates have been commonly used in the biochemical investigations of temporomandibular joint (TMJ) pathology. However, due to presence of adhesions in the diseased temporomandibular joint, full equilibration between the injected saline and the synovial fluid may not be achieved in all cases. We measured calcium ion concentration in the saline aspirates and the plasma to assess the degree of dilution of the synovial fluid by the injected media. Saline aspirates obtained prior to the arthroscopic examination of 17 patients with painful TMJs not responding to 3 months of conservative treatment were analysed for their calcium content by a highly sensitive spectrophotometric autoanalyser. In 10 patients with unilateral symptoms, the contralateral asymptomatic side was used as a control. Using a concentration volume equation the amount of the synovial fluid in the saline aspirates was calculated. The yield of the saline aspirates was variable ranging from 330 to 1000 microl. The mean calcium level was 0.787 mg/dl in the symptomatic group (C.I. 95% 0.337-1.237 mg/dl) and 0.512 mg/dl (C.I. 95% 0.235-0.797) in the asymptomatic group. Using a Student t-test there was no significant difference between the two groups. Furthermore, there was no demonstrable correlation between the volume of the aspirate and its synovial fluid content. This study confirms that the saline aspirate may not be a representative sample of the TMJ synovial fluid, and that expression of the results of the biochemical assays per volume of the aspirate may be misleading.

Copper stimulates human oral fibroblasts in vitro: a role in the pathogenesis of oral submucous fibrosis.

Copper is implicated in the pathogenesis of several fibrotic disorders. Areca nut has been shown to have a high copper content and areca chewing is associated with oral submucous fibrosis (OSF). The effects of copper on human oral fibroblasts were investigated in vitro. Human oral fibroblasts were incubated with copper chloride (CuCl2) at concentrations ranging from 0.01 microM to 500 microM for 24 h, and in vitro cell proliferation was assayed by incorporation of tritiated-thymidine; soluble and non-soluble collagen synthesis was assayed using tritiated-proline. Addition of copper chloride at concentrations ranging from 0.1 microM to 50 microM increased the collagen synthesis by the oral fibroblasts compared with growth without copper (P<0.05). The addition of copper chloride neither increased the synthesis of non-collagenous proteins by the fibroblasts nor influenced their proliferation rate. We conclude that copper upregulates collagen production in oral fibroblasts. This appears to be concentration dependent, with peak collagen synthesis at 50 microM CuCl2. These in vitro results taken together with the recent findings of copper in oral biopsies from OSF subjects support the hypothesis that copper in areca nut acts as a mediator of OSF.

Extracellular ADP is a powerful osteolytic agent: evidence for signaling through the P2Y(1) receptor on bone cells.

There is increasing evidence that extracellular nucleotides act on bone cells via P2 receptors. This study investigated the action of ADP and 2-methylthioADP, a potent ADP analog with selectivity for the P2Y(1) receptor, on osteoclasts, the bone-resorbing multinuclear cells. Using three different assays, we show that ADP and 2-methylthioADP at nanomolar to submicromolar levels caused up to fourfold to sixfold increases in osteoclastic bone resorption. On mature rat osteoclasts, cultured for 1 day on polished dentine disks, peak effects on resorption pit formation were observed between 20 nM and 2 microM of ADP. The same concentrations of ADP also stimulated osteoclast and resorption pit formation in 10-day mouse marrow cultures on dentine disks. In 3-day explant cultures of mouse calvarial bones, the stimulatory effect of ADP on osteoclast-mediated Ca(2+) release was greatest at 5-50 microM and equivalent to the maximal effects of prostaglandin E(2). The ADP effects were blocked in a nontoxic manner by MRS 2179, a P2Y(1) receptor antagonist. Using in situ hybridization and immunocytochemistry, we found evidence for P2Y(1) receptor expression on both osteoclasts and osteoblasts; thus, ADP could exert its actions both directly on osteoclasts and indirectly via P2Y(1) receptors on osteoblasts. As a major ATP degradation product, ADP is a novel stimulator of bone resorption that could help mediate inflammatory bone loss in vivo.

Staphylococcus aureus fibronectin binding proteins are essential for internalization by osteoblasts but do not account for differences in intracellular levels of bacteria.

Staphylococcus aureus is a major pathogen of bone that has been shown to be internalized by osteoblasts via a receptor-mediated pathway. Here we report that there are strain-dependent differences in the uptake of S. aureus by osteoblasts. An S. aureus septic arthritis isolate, LS-1, was internalized some 10-fold more than the laboratory strain 8325-4. Disruption of the genes for the fibronectin binding proteins in these two strains of S. aureus blocked their ability to be internalized by osteoblasts, thereby demonstrating the essentiality of these genes in this process. However, there were no differences in the capacity of these two strains to bind to fibronectin or osteoblasts. Analysis of the kinetics of internalization of the two strains by osteoblasts revealed that strain 8325-4 was internalized only over a short period of time (2 h) and to low numbers, while LS-1 was taken up by osteoblasts in large numbers for over 3 h. These differences in the kinetics of uptake explain the fact that the two strains of S. aureus are internalized by osteoblasts to different extents and suggest that in addition to the fibronectin binding proteins there are other, as yet undetermined virulence factors that play a role in the internalization process.

Interferon gamma (IFN-gamma) may reverse oral submucous fibrosis.

Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity and oropharyngx characterised by fibrosis in the submucosa leading to progressive limitation of the mouth opening. Interferon gamma (IFN-gamma) is a known anti-fibrotic cytokine. In this study we have investigated: a) the effect of IFN-gamma on collagen synthesis by arecoline-stimulated OSF fibroblasts in vitro (n=5), b) the effect of intra-lesional IFN-gamma on the fibrosis of OSF patients (n=29) and c) the immunohistochemical analysis of pre- and post-treatment inflammatory cell infiltrates and cytokine levels in the lesional tissue (n=29). The results show that the increased collagen synthesis in vitro in response to arecoline was inhibited in the presence of IFN-gamma (0.01-10.0 U/ ml) in a dose-related way. In an open uncontrolled study intra-lesional IFN-gamma treatment showed improvement in the patients mouth opening from an inter-incisal distance before treatment of 21 +/- 7 mm, to 30 +/- 7 mm immediately after treatment and 30 +/- 8 mm 6-months later, giving a net gain of 8 +/- 4 mm (42%) (range 4-15 mm). Patients also reported reduced burning dysaesthesia and increased suppleness of the buccal mucosa. The post-treatment immunohistochemistry showed a decreased amount of inflammatory cell infiltrate and an altered level of cytokines compared with the pre-treatment lesional tissue. The effect of IFN-gamma on collagen synthesis appears to be a key to the treatment of these patients, and intra-lesional injections of the cytokine may have a significant therapeutic effect on OSF.

pH dependence of bone resorption: mouse calvarial osteoclasts are activated by acidosis.

We examined the effects of HCO(3)(-) and CO(2) acidosis on osteoclast-mediated Ca(2+) release from 3-day cultures of neonatal mouse calvaria. Ca(2+) release was minimal above pH 7.2 in control cultures but was stimulated strongly by the addition of small amounts of H(+) to culture medium (HCO(3)(-) acidosis). For example, addition of 4 meq/l H(+) reduced pH from 7.12 to 7.03 and increased Ca(2+) release 3.8-fold. The largest stimulatory effects (8- to 11-fold), observed with 15-16 meq/l added H(+), were comparable to the maximal Ca(2+) release elicited by 1,25-dihydroxyvitamin D(3) [1, 25(OH)(2)D(3); 10 nM], parathyroid hormone (10 nM), or prostaglandin E(2) (1 microM); the action of these osteolytic agents was attenuated strongly when ambient pH was increased from approximately 7.1 to approximately 7.3. CO(2) acidosis was a less effective stimulator of Ca(2+) release than HCO(3)(-) acidosis over a similar pH range. Ca(2+) release stimulated by HCO(3)(-) acidosis was almost completely blocked by salmon calcitonin (20 ng/ml), implying osteoclast involvement. In whole mount preparations of control half-calvaria, approximately 400 inactive osteoclast-like multinucleate cells were present; in calvaria exposed to HCO(3)(-) acidosis and to the other osteolytic agents studied, extensive osteoclastic resorption, with perforation of bones, was visible. HCO(3)(-) acidosis, however, reduced numbers of osteoclast-like cells by approximately 50%, whereas 1,25(OH)(2)D(3) treatment caused increases of approximately 75%. The results suggest that HCO(3)(-) acidosis stimulates resorption by activating mature osteoclasts already present in calvarial bones, rather than by inducing formation of new osteoclasts, and provide further support for the critical role of acid-base balance in controlling osteoclast function.

Oral submucous fibrosis patients have altered levels of cytokine production.

Oral submucous fibrosis (OSF) is a pre-malignant fibrotic lesion of the mouth in betel quid chewers and is characterised by dense bands of collagen in the juxta-epithelial region preceded by inflammation. We have investigated the spontaneous and stimulated production of cytokines by peripheral blood mononuclear cells (PBMC) from OSF patients and compared them with genetically-related relatives, Indian and Caucasian control subjects. The cytokines studied included: interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). The results show: a) significant differences in the stimulated versus non-stimulated levels of IL-1beta, IL-6, IL-8 and TNF-alpha but not of IFN-gamma production by patients, and in the relatives' stimulated versus non-stimulated levels of IL-1beta, IL-6 and IFN-gamma; b) no difference in the spontaneous cytokine production between any two groups; and c) significant increases in the patients' stimulated cytokines compared to the Caucasian and Indian controls (P< or =0.050). These results demonstrate increased levels of proinflammatory cytokines and reduced anti-fibrotic IFN-gamma in patients with OSF, which may be central to the pathogenesis of OSF.

Mechanisms of internalization of Staphylococcus aureus by cultured human osteoblasts.

Staphylococcus aureus is an important bone pathogen, and evidence shows that this organism is internalized by chick osteoblasts. Here we report that S. aureus is internalized by human osteoblasts. Internalization was inhibited by monodansylcadaverine and cytochalasin D and to a lesser extent by ouabain, monensin, colchicine, and nocodazole. We propose that internalization occurs via a receptor-mediated pathway, requiring the participation of cytoskeletal elements, principally actin.

Effect of ultrasound on the production of IL-8, basic FGF and VEGF.

Therapeutic angiogenesis is the controlled induction or stimulation of new blood vessel formation to reduce unfavourable tissue effects caused by local hypoxia and to enhance tissue repair. The effects of ultrasound on wound healing, chronic ulcers, fracture healing and osteoradionecrosis may be explained by the enhancement of angiogenesis. The aim of this study was to identify which cytokines and angiogenesis factors are induced by ultrasound in vitro. Two ultrasound machines were evaluated, a "traditional" (1 MHz, pulsed 1:4, tested at four intensities), and a "long wave" machine (45 kHz, continuous, also tested at four intensities). The ultrasound was applied to human mandibular osteoblasts, gingival fibroblasts and peripheral blood mononuclear cells (monocytes). The following cytokines and angiogenesis factors were assayed by ELISA techniques: interleukin-1beta(IL-1beta), IL-6, tumour necrosis factor alpha (TNF-alpha), IL-8, fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF).A slight stimulation of IL-1beta was noted in all cell types. There was no difference in the IL-6 and TNF-alpha levels. The angiogenesis-related cytokines, IL-8 and bFGF, were significantly stimulated in osteoblasts, and VEGF was significantly stimulated in all cell types. Both ultrasound machines produced similar results, and the optimum intensities were 0.1 and 0. 4 W/cm2 (SATA) with 1 MHz ultrasound, and 15 and 30 mW/cm2 (SATA) with 45 kHz ultrasound.The results show that therapeutic ultrasound stimulates the production of angiogenic factors such as IL-8, bFGF and VEGF. This may be one of the mechanisms through which therapeutic ultrasound induces angiogenesis and healing.

In vitro effects of therapeutic ultrasound on cell proliferation, protein synthesis, and cytokine production by human fibroblasts, osteoblasts, and monocytes.

PURPOSE: The aim of this study was to evaluate several in vitro effects of ultrasound that could revert or prevent the hypoxia, hypovascularity, and hypocellularity observed in osteoradionecrosis. MATERIALS AND METHODS: Two different ultrasound machines were evaluated, a "traditional" (1 MHz, pulsed 1:4) and a "long wave" (45 kHz, continuous) machine, tested at various intensities. Ultrasound was applied to human gingival fibroblasts, mandibular osteoblasts, and monocytes. The assays performed were cell proliferation (DNA synthesis), collagen and noncollagenous protein (NCP) synthesis, and cytokine production (ELISA) involving interleukin (IL) 1 beta, IL-6, and IL-8, tumor necrosis factor alpha (TNF alpha), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF). RESULTS: Both ultrasound machines induced increased cell proliferation in fibroblasts and osteoblasts, between 35% and 52%. The collagen and NCP synthesis were also significantly enhanced to levels up to 112%, the best results being with the 45-kHz machine. The ELISA results showed a slight stimulation of IL-1 beta by all cell types; there was no difference in IL-6 and TNF alpha levels. The angiogenesis-related cytokines evaluated were significantly stimulated: IL-8 and bFGF production was enhanced in osteoblasts, and VEGF production was stimulated in all three cell types. Both ultrasound machines produced the same results, with the recommended intensities being 15 and 30 mW/cm2(SA) for the 45-kHz ultrasound, and 0.1 and 0.4 W/cm2(SAPA) for the 1 MHz ultrasound. CONCLUSIONS: Therapeutic ultrasound induces in vitro cell proliferation, collagen/NCP production, bone formation, and angiogenesis. These findings support its use in prospective clinical trials for the prevention and treatment of osteoradionecrosis.

Molecular chaperones stimulate bone resorption.

Molecular chaperones, also known as heat shock proteins (hsp), are intracellular proteins found in all cells that catalyze protein folding. We have discovered that one class of bacterial molecular chaperone, the chaperonins, are potent inducers of bone resorption. To address the question of whether the osteolytic activity of the chaperonins was unique to this protein class, or was a common attribute of molecular chaperones generally, we have examined a number of bacterial and mammalian molecular chaperones for activity in the murine calvarial bone resorption assay. All the Escherichia coli molecular chaperones (groEL, groES, and dnaK) were active. The osteolytic activity of groEL was inhibited by indomethacin and the natural antagonist of interleukin-1 receptor antagonist (IL-1ra) but was unaffected by neutralization of tumor necrosis factor (TNF) or inhibition of 5-lipoxygenase. Mammalian molecular chaperones of molecular mass 27, 47, 70, and 90 kDa were also tested and, with the exception of the 47 kDa protein, all showed activity in the murine calvarial assay. Molecular chaperones appear, therefore, to have the capacity to modulate the cellular processes in bone explant cultures, resulting in resorption of the calcified matrix. The possibility that these proteins could play a role in the normal or pathological remodeling of bone is discussed.