Bone cement extracts modulate the osteoprotegerin/osteoprotegerin-ligand expression in MG63 osteoblast-like cells

The osteoprotegerin-ligand (OPG-L) has been identified as the essential factor required for osteoclastogenesis, and its effects are prevented by the osteoprotegerin (OPG). The OPG-L/OPG balance plays a crucial role in coordinating the sequence of osteoclast and osteoblast differentiation during the bone remodeling. The aim of the study was to investigate if polymethylmethacrylate-based cements are able to modulate the expression of OPG-L/OPG in MG63 cells, which are known to have high levels of OPG and inducible expression of OPG-L. Four radio-opaque cements. namely Sulfix-60, CMW1, CMW2 and CMW3, were polymerized for either 1 h or 7 d. MG63 were incubated for 24 h with culture medium only, cement extracts and 2 microg/ml of human recombinant IL-1beta as positive control. An RT-PCR was performed to detect the OPG and OPG-L expression, and the house-keeping gene, GAPDH, was used as a reference for the semi-quantitative analysis. An increase in the OPG-L band density was observed for all cements, and consequently, the OPG-L/OPG ratio also increased. The ability of bone cements to induce the expression of OPG-L could be a co-factor in the development of osteolysis at the bone-cement interface.     

Cell culture methods for testing biocompatibility

Cell culture systems may be of value in testing the biocompatibility of prosthetic materials before they are introduced into clinical use. In recent years, in vitro methods for assaying biomaterials have gained in importance owing to the growing concern over the use of animals for biomaterials testing. Significant effort is therefore being focused toward developing predictive and quantitative, but also simple and reliable, methods of testing using cultured cells. At present, a number of methods for measuring both the cytotoxicity and the specific cytocompatibility of different materials are available. The usefulness of these systems is no longer confined to screening new materials; they can be used to study the mechanisms of action of various materials during tissue/material interaction. This paper reviews the published literature on the use of cell culture models in evaluating biocompatibility and reports on the personal experience of the authors, who have been using cell culture systems for many years and for different purposes.     

Cryopreservation of all prezygotes in patients at risk of severe hyperstimulation does not eliminate the syndrome, but the chances of pregnancy are excellent with subsequent frozen-thaw transfers

In-vitro fertilization patients (n = 15) at risk of ovarian hyperstimulation syndrome (OHSS) (oestradiol > or =4500 pg/ml on the day of human chorionic gonadotrophin administration and 25 or more follicles of intermediate or large size) underwent aspiration of all follicles and cryopreservation of all fertilized oocytes at the pronuclear stage. Patients were monitored for up to 2 weeks post- retrieval. Subsequent transfer of cryopreserved-thawed embryos was performed in programmed cycles using exogenous oestrogen and progesterone for endometrial preparation. Two patients (13%) developed OHSS necessitating hospitalization and vaginal aspiration of ascitic fluid. Two other patients (13%) developed moderate OHSS requiring ascitic fluid vaginal aspiration in the office setting, with dramatic improvement of the condition. Subsequent transfer of cryopreserved- thawed embryos yielded a clinical pregnancy rate of 58% per transfer and ongoing or delivery rates of 42 and 67% per transfer and per patient respectively. By eliminating pregnancy potential with cryopreservation of all prezygotes and examining the pregnancy potential with subsequent cryopreserved-thawed transfers, it is concluded that OHSS is reduced, but not eliminated for patients at risk. Subsequent transfer of cryopreserved-thawed prezygotes in a programmed cycle with exogenous steroids yields an excellent pregnancy rate.      

Diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is a true pediatric and medical emergency. Diagnosis should be entertained and confirmed within 30 min of presentation. Any delay in making the diagnosis or instituting fluid and electrolyte correction is likely to increase morbidity and mortality. Slow and careful monitoring and correction of water, sodium and potassium levels should decrease DKA-associated problems with either continuous intravenous low-dose insulin or intramuscular insulin protocols designed to slowly bring the hyperglycemic and hyperosmotic state towards normal homeostasis. Special attention should be paid to potassium replenishment. Most patients do not require bicarbonate replacement. Cerebral edema, when it occurs, is associated with an approximately 50% morbidity and mortality; therefore, all attempts should be made at early recognition and prevention since treatment is less than ideal. Recurrent ketoacidosis is often related to omitted insulin and major psychosocial turmoil in the family, such as depression substance abuse, physical and/or sexual abuse. Prevention of recurrent DKA remains a major challenge for diabetologists and involves detailed assessment of family psychodynamics plus responsibility for home monitoring and insulin administration by a mature adult. Sick day guidelines should be taught and reviewed frequently in an effort to decrease ketoacidosis and metabolic decompensation during episodes of intercurrent illness. □ Cerebral edema, diabetic ketoacidosis, diabetes mellitus, DKA, sick day guidelines, sick day management, type 1 diabetes mellitus     

A STD/HIV prevention trial among adolescents in managed care

OBJECTIVE: To determine if sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV) infection, risk assessment, and education tools provided as part of office-based primary care reduce adolescent risky sexual behaviors. DESIGN: A randomized intervention trial with 3- and 9-month follow-up. SETTING: Five staff-model managed care sites in Washington, DC (n = 19 pediatricians). PATIENTS: Consecutive 12- to 15-year-olds receiving a general health examination; 81% minority. Participation rate = 215/432 (50%). Nine-month follow-up rate = 197/215 (92%). INTERVENTION: Audiotaped STD risk assessment and education about staying safe (safer = condoms, safest = abstinence). MAIN OUTCOME MEASURES: Adolescent-reported sexual intercourse and condom use. RESULTS: More intervention adolescents reported pediatrician discussion on 11/13 sexual topics. Although more vaginal intercourse (odds ratio [OR] = 2.46, 95% confidence interval [CI] = 1.04-5.84) was reported in the intervention group at 3 months, this was not true of overall sexual intercourse (OR = 1.55, 95% CI =.73-3.32). More sexually active adolescents reported condom use in the intervention group at 3 months (OR = 18.05, 95% CI = 1.27-256.03). At 9 months, there were no group differences in sexual behaviors; however, more signs of STD were reported by the control (7/103) than the intervention group (0/94). CONCLUSIONS: STD risk assessment and education tools administered in a single office visit facilitated STD/HIV prevention education. Any impact on sexual activity and condom use was short-lived. Further research is needed to develop brief, office-based sexual risk reduction for young adolescents.     

The influence of alumina and ultra-high molecular weight polyethylene particles on osteoblast-osteoclast cooperation

Particle-induced macrophage activation, mainly by UHMWPE wear, has been recognized as the biological mechanism leading to periprosthetic bone resorption, which is responsible for the loosening of the total hip replacements (THR). Ceramic-on-ceramic implants have been advocated as a means of reducing wear products. Many studies investigated the effect of alumina (Al(2)O(3)) particles on monocytes/macrophages, but only limited information are available on their participation to bone turnover. An in vitro model was performed to investigate how Al(2)O(3) and UHMWPE particles may influence the osteoblast-osteoclast interaction: human osteoblasts (HOB) were obtained from trabecular bone, while osteoclasts were derived from peripheral blood mononuclear cells (PBMC) of healthy donors. The amount of IL6, TNF alpha, GM-CSF, and other factors acting on the bone turnover, i.e. the 'receptor activator of NF kappa B' ligand (RANKL) and osteoprotegerin (OPG), was detected in culture medium of particle-challenged HOB (HOB-CM). The Al(2)O(3) and UHMWPE particles did not affect either cell viability or TNF and GM-CSF release, while the increase in IL6 release seemed to be dependent on the particle concentration. UHMWPE increased the release of RANKL from HOB, while OPG and OPG-to-RANKL ratio were significantly inhibited. The ability of HOB-CM to promote osteoclastogenesis was tested via osteoblast/monocyte cooperation: after seven days of culture UHMWPE HOB-CM induced a large amount of multinucleated TRAP-positive giant cells, as well as significantly reduced the amount of IL6, GM-CSF and RANKL in the supernatant. With regard to the inductive effect on the osteoclastogenesis, our results show that the Al(2)O(3) wear debris are less active.     

Anti-HIV effects of chloroquine: inhibition of viral particle glycosylation and synergism with protease inhibitors

OBJECTIVE: We tested the effects of chloroquine (CQ) on glycosylation of HIV particles and in combination with protease inhibitors (PIs) on HIV replication and on P-glycoprotein (P-gp)/multidrug resistance protein-1 (MRP1). DESIGN: CD4 cell lines were infected with laboratory strains and peripheral blood mononuclear cells were infected with primary isolates for evaluation of the anti-HIV effects. Peripheral blood lymphocytes were evaluated for of P-gp and MRP1 functions. METHODS: HIV replication was assessed by enzyme-linked immunosorbent assay. HIV glycosylation was measured by metabolic labeling of viral particles with [H] glucosamine. Synergism was tested using isobolograms. P-gp and MRP1 functions were assayed using rhodamine 123 (Rh123) and carboxyfluorescein (CF) efflux assays, respectively. RESULTS: CQ alone inhibited HIV replication and glycosylation in a dose-dependent manner. In combination with indinavir (IDV), ritonavir, or saquinavir (SQV), CQ had a synergistic effect at concentrations found in plasma of subjects receiving malaria prophylaxis. CQ decreased the 50% effective concentration of IDV in primary isolates from Africa and restored the response to IDV or SQV in 3 PI-resistant isolates. CQ increased the block of Rh123 and CF efflux activity exerted by PIs. CONCLUSION: The inhibitory effects of CQ on HIV glycosylation are associated with synergistic effects in combination with PIs. The CQ/PI combination exerts combined inhibitory effects on P-gp and MRP1 function.     

A prospective, randomised, controlled trial using a Mg-hydroxyapatite - demineralized bone matrix nanocomposite in tibial osteotomy

We in vivo investigated the bone healing ability of a nanocomposite (DBSint®), constituted by biomimetic nano-structured Mg-hydroxyapatite (SINTlife®) and human demineralized bone matrix. Thirty-one subjects undergoing high tibial osteotomy for genu varus were randomly assigned to three groups: during surgery, DBSint® was inserted into nine patients, SINTlife® in thirteen patients and lyophilised bone chips, that is the routine surgery, in nine subjects. As outcome measures, clinical, radiographic and histomorphometry scores were calculated. The osseointegration was evaluated by imaging six weeks, three, six and twelve months after surgery. At six-week follow-up, DBSint® showed a significantly higher osseointegration rate in comparison with lyophilised bone chips (p = 0.008). At the same follow-up, CT-guided bone biopsies were obtained and analysed by histomorphometry: a good osteogenetic potential was demonstrated with DBSint®, as well as with SINTlife® and controls. Unresorbed material was evident with DBSint® and SINTlife®, with a significantly higher percentage in SINTlife® group. At 1-year follow-up, DBSint® was demonstrated as effective and safe as SINTlife® and lyophilized bone chips. More significant results could be obtained by continuing the clinical trial, by increasing the patient number and the study power. Eventually, the role of non-resorbed graft remnants is still unclear and requires further investigation.