Incorporation of tocopherol acetate-containing particles in acrylic bone cement

Acrylic bone cement (BC) is used in orthopaedic surgery to anchor cemented prostheses to bone. Association of antioxidant molecules to BC may suppress reactive species injury which contributes to implant failure. Tocopherol acetate (ATA)-loaded polymethylmethacrylate (PMMA) particles (ATA(PMMA)) were prepared by single emulsion solvent evaporation technique and were incorporated into BC. An encapsulation efficiency of 84% (w/w) was obtained and drug release studies showed distinct ATA release profiles and mechanisms before and after particle incorporation into BC. Experimental data, analysed using first-order, Higuchi and Korsmeyer-Peppas models revealed that ATA was released from particles by a Fickian diffusion mechanism while a non-Fickian transport was observed upon particle incorporation in BC. There were no changes in the mechanical properties of BC specimens containing ATA(PMMA) particles, in contrast to what was observed when ATA was loaded directly into BC. Overall, ATA(PMMA) particles are potential carriers for the incorporation of an antioxidant drug into BC.

The teaching of management of the pulp in primary molars in Europe: a preliminary investigation in Ireland and the UK

AIM

This was to determine which methods of primary pulp therapy are currently being taught in European dental schools starting with a preliminary study in the UK and Ireland.

METHODS

A questionnaire, based on that used in a USA study, was sent to paediatric dentistry staff at each of 18 dental schools in Ireland and the UK.

RESULTS

There was a response rate of 87%. All respondents taught the vital pulpotomy technique in primary molars but no uniformity was found regarding pulpectomy, indirect and direct pulp capping techniques. Most respondents, 92.9%, taught the use of ferric sulphate for vital pulpotomy. Formocresol, mineral trioxide aggregate and calcium hydroxide accounted for the remainder, with some respondents electing to teach different medicaments depending on whether the students were at undergraduate or postgraduate level.

CONCLUSIONS

Formocresol is no longer the most commonly taught pulp medicament in dental schools in Ireland and the UK.

Evaluation of bone mechanical strenght and fracture risk assessment (Frax) in patients with hip joint replacement surgery

BACKGROUND

Fracture risk assessment tools are useful to calculate the long term probability of osteoporotic fracture. However, how it reflects bone quality is unknown. The aim of this study was to correlate the WHO clinical fracture risk assessment tool, FRAX, with bone mechanical properties.

METHODS

Six patients submitted to hip replacement surgery, either due to osteoporotic fractures or to osteoarthritis, were evaluated. Bone samples were collected and the mechanical properties assessed by compression tests. Patients' data regarding the presence of clinical risk factors for fracture were registered. Laboratorial assessment of bone metabolic parameters and a dual X-ray absorptiometry(DXA) were done.

RESULTS

Analysis of the load-displacement curves showed that patients with fragility fractures (n=4) had low values of elastic modulus, yield load and energy absorbed until yield point. Osteoarthritis patients tend to have a better biomechanical performance.Femoral neck DXA scan was also performed in 3 patients. Fragility fracture patients had a lower bone mineral density than the patients with osteoarthritis. FRAX algorithm was applied and a positive relation was found between FRAX results and biomechanical parameters. Blood bone metabolic markers were within the normal range for all the subjects.

CONCLUSIONS

The worse mechanical properties observed in the fragility fracture patients were related to high probability of fracture given by FRAX. These observations, in a very small sample, need further confirmation. However, they suggest that the fracture risk assessment tool, FRAX, may reflect the current mechanical bone behavior of the patient.

Chronic arthritis directly induces quantitative and qualitative bone disturbances leading to compromised biomechanical properties

OBJECTIVES

Rheumatoid arthritis (RA) is associated with an increased risk of fragility fractures. In RA patients, the direct effect of inflammation on bone is difficult to study because their skeleton is also affected by medication with corticosteroids and other drugs as well as aging and menopause, which contribute to bone fragility. This study used an animal model of chronic arthritis to evaluate the direct impact of chronic inflammation on biomechanical properties and structure of bone.

METHODS

In the SKG mouse chronic arthritis model three point bending tests were performed on femoral bones and compression tests on vertebral bodies. Collagen structure was analysed using second-harmonic generation (SHG) imaging with a two-photon microscope, ultramorphology by scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS) and bone density using water pycnometer.

RESULTS

Arthritic bones had poor biomechanical quality compared to control bones. SHG, SEM and pycnometry disclosed variable signs of impaired collagen organization, poor trabecular architecture and low bone density.

CONCLUSION

Present data demonstrate for the first time that chronic inflammation per se, without confounding influence of drugs and aging, leads to impairment of bone biomechanics in terms of stiffness, ductility and ultimate strength (fracture).

Evaluation of CSF neurotransmitters and folate in 25 patients with Rett disorder and effects of treatment

BACKGROUND

Rett disorder (RD) is a progressive neurodevelopmental entity caused by mutations in the MECP2 gene. It has been postulated that there are alterations in the levels of certain neurotransmitters and folate in the pathogenesis of this disease. Here we re-evaluated this hypothesis.

PATIENTS AND METHODS

We evaluated CSF folate, biogenic amines and pterines in 25 RD patients. Treatment with oral folinic acid was started in those cases with low folate. Patients were clinically evaluated and videotaped up to 6 months after therapy.

RESULTS

CSF folate was below the reference values in 32% of the patients. Six months after treatment no clinical improvement was observed. Three of the four patients with the R294X mutation had increased levels of a dopamine metabolite associated to a particular phenotype. Three patients had low levels of a serotonin metabolite. Two of them were treated with fluoxetine and one showed clinical improvement. No association was observed between CSF folate and these metabolites, after adjusting for the patients age and neopterin levels.

CONCLUSION

Our results support that folinic acid supplementation has no significant effects on the course of the disease. We report discrete and novel neurotransmitter abnormalities that may contribute to the pathogenesis of RD highlighting the need for further studies on CSF neurotransmitters in clinically and genetically well characterized patients.

Stereotypies in Rett syndrome: Analysis of 83 patients with and without detected MECP2 mutations

BACKGROUND

Hand stereotypies are considered a hallmark of Rett syndrome (RTT) and are usually described as symmetric movements at the midline. However, related pathologies may show the same type of involuntary movement. Furthermore, patients with RTT also have stereotypies with other localizations that are less well characterized.

METHODS

We analyzed stereotypies in 83 patients with RTT, 53 with and 30 without a mutation detected in the MECP2 gene. Patients were observed and videotaped always by the same pediatric neurologist. Stereotypies were classified, and data were submitted to statistical analysis for comparison of mutation-positive and -negative patients and analysis of their evolution with the disease.

RESULTS

All the patients showed hand stereotypies that coincided with or preceded the loss of purposeful hand movements in 62% of the patients with MECP2 mutations. The hair pulling stereotypy was more frequent in the group with detected mutations, whereas hand washing was not. Hand gaze was absent in all RTT patients with MECP2 mutations. Patients with MECP2 mutations also had more varied stereotypies, and the number of stereotypies displayed by each patient decreased significantly with age in this group. In all patients, stereotypies other than manual tended to disappear with the evolution of the disease.

CONCLUSIONS

Although symmetric midline hand stereotypies were not specific to patients with an MECP2 mutation, some of the other stereotypies seemed to be more characteristic of this group. In patients younger than 10 years and meeting the necessary diagnostic criteria of Rett syndrome, the association of hand stereotypies without hand gaze, bruxism, and two or more of the other stereotypies seemed to be highly indicative of the presence of an MECP2 mutation.

An outbreak of catalase-negative methicillin-resistant Staphylococcus aureus

The wide dissemination of a major epidemic methicillin-resistant Staphylococcus aureus (MRSA) clone in Brazilian hospitals (Brazilian clone) limits the value of molecular typing techniques such as pulsed-field gel electrophoresis (PFGE) for outbreak investigation. We report the first outbreak of a catalase-negative strain of MRSA, which was initially detected by the unusual result of this phenotypical test. The outbreak occurred in the Hospital Sanatorinhos de Carapicuíba, a 237-bed secondary hospital located in São Paulo, Brazil. From May to August 2002, a total of 11 MRSA isolates were recovered from four patients in the intensive care unit. All the isolates were catalase negative and susceptible only to vancomycin and linezolid. Three of the four patients eventually died. Molecular typing demonstrated an indistinguishable PFGE pattern among the 11 isolates, with similarities to the Brazilian clone and the hospital's usual MRSA strain. This report emphasizes the importance of an uncommon phenotypical result as a marker for initiating an outbreak investigation and should encourage clinical laboratories to recognize and report such isolates.

66 HISTIOTROPHIC NUTRITION AND IRON TRANSFER ACROSS THE MATERNO-FETAL INTERFACE IN NUCLEAR TRANSFER-DERIVED SOMATIC CATTLE CLONES

The histiotrophic nutrition by the endometrial glands and the materno-fetal interface in the cloned cattle placenta were analyzed in order to investigate the iron transfer. Placentomes and intercaruncular region samples were recovered at term Caesarean delivery from 14 cloned cattle and 10 controls, fixed in 4% paraformaldehyde and 10% formaldehyde in PBS, processed and stained for light microscopy (hematoxylin-eosin, picrosirius, and Masson's trichrome), histochemistry [Perls, acid phosphatase and periodic acid Schiff (PAS) reactions], and immunohistochemistry (with rabbit anti-pig uteroferrin antibody because the uteroferrin is an iron transporter protein). In the controls we verified blood extravasations in the materno-fetal interface between the uterine and the trophoblast epithelium characterized by hemophagous areas with consequent erythrophagocytosis by the adjacent trophoblast. This content presented extravasated erythrocytes, plasm, cell debris, and cells in a probable apoptotic process. The Perls histochemical reactions that exposed the ferric iron in the placentomes were positive, as was the uteroferrin immunohistochemistry in the trophoblast cytoplasm and in other deep points in the placentomes. The histochemical reactions, demonstrating the acid phosphatase enzyme that detects the phagocytic activity, were positive in the mesenchyme and trophoblast, with a weak stain in an endometrial stroma. In the top of fetal villi, mainly in the binucleate cells, we visualized accumulations of PAS-positive secretions, indicating the presence of mucoid material. The uterine gland epithelium was columnar-type and in the gland lumina there were cell debris and PAS-positive mucoid secretions. We confirmed the reactivity of the uterine glands to the acid phosphatase enzyme and to the Perls reaction in the epithelium and in the gland lumina. The uteroferrin immunohistochemistry showed a strong stain in the cytoplasm of the endometrial glands cells and in the lumina. In the NT bovine placentae, the blood extravasations between uterine and trophoblast epithelium were aberrant. There was also the remodeling of the maternal connective tissue (endometrial stroma) in this area. We also demonstrated phagocytic uptake of uteroferrin by the trophoblast, although the histochemical and immunohistochemical reactions were weak in the trophoblast of the placentomes and in the endometrial glands of the intercaruncular region, when compared with the controls. The results obtained by the histochemistry and immunohistochemistry indicated that these sites of transfer substances from mother to fetus are very important in providing adequate nutrition to the fetus, key to a successful pregnancy in NT bovines. This work was funded by FAPESP, Brazil.

Surface studies on acrylic bone cement

Poly(methyl methacrylate) (PMMA) is used to fill the gap between the prosthesis and the surrounding bone in cemented arthroplasties. Biocompatibility problems related to bone cement application limit the clinical success of these cemented arthroplasties. Being the cement surface in close connection with the living bone, it is reasonable to assume that surface properties such as, surface composition and surface energy, will play a role in the biomaterial performance. X-ray photoelectron spectroscopy (XPS) analysis and surface energy studies were carried out during 4 months, in order to assess a possible correlation between aging time and surface changes. The aging of PMMA, in a biological model fluid, strongly influences the composition and wettability of the cement surface. These changes may be explained through the hydrolysis of PMMA ester groups and the subsequent hydrogen bonding. Although our study does not exactly reproduce the in vivo environment surrounding a prosthesis, it suggests that the changes in the composition and wettability of the surface may modulate the host response towards the implant, thus contributing to its loosening.

The effect of ethanol on acrylic bone cement

Prosthesis loosening is a major problem associated with the use of poly(methyl methacrylate) (PMMA) bone cement that may be related to a peri-implant vacuolisation commonly observed at bone-cement interface. Methyl methacrylate (MMA) monomer may be one of the cement components partly responsible for the mentioned vacuolisation due to a cytotoxic effect associated to this compound. Alcoholism has been related to bone necrosis in predisposed individuals. Furthermore, ethanol has been shown to clean material with adherent cement debris during cleaning procedure in laboratory. Consequently, we have decided to study whether ethanol will also be related to an increased liberation of MMA from the polymer matrix. 'In vitro' release studies using PMMA plates were conducted to access the role of ethanol on the liberation of the monomer. Contact angle measurements and surface tension estimation were also carried out in order to find a possible effect of ethanol on surface cement properties. Results suggest that ethanol, even in small quantities, enhances the leaching of the monomer from the polymer matrix, but does not considerably change the wettability properties of the cement surface.

A functional promoter polymorphism in the macrophage migration inhibitory factor (MIF) gene associated with disease severity in rheumatoid arthritis

The macrophage migration inhibitory factor (MIF) is a potent pro-inflammatory cytokine and regulates the anti-inflammator effects of glucocorticoids. An important role for MIF within the cytokine cascade is to act in concert with endogenous glucocorticoids to control the set-point and magnitude of the inflammatory response. Elevated expression of MIF in the circulation and in the synovial joint has been documented in rheumatoid arthritis. MIF also has been linked to the development of joint damage and disease pathology in experimental animal models. We describe herein a novel CATT-tetranucleotide repeat polymorphism at position -794 of the human Mif gene and show that it functionally affects the activity of the MIF promoter in gene reporter assays. We describe four genotypes which comprise 5, 6, 7, or 8-CATT repeat units and show that the 5-CATT allele has the lowest level of basal and stimulated MIF promoter activity in vitro. The presence of the low expressing, 5-CATT repeat allele correlated with low disease severity in a cohort of rheumatoid arthritis patients.

RAGE and arthritis: the G82S polymorphism amplifies the inflammatory response

The receptor for advanced glycation end products (RAGE) and its proinflammatory S100/calgranulin ligands are enriched in joints of subjects with rheumatoid arthritis (RA) and amplify the immune/inflammatory response. In a model of inflammatory arthritis, blockade of RAGE in mice immunized and challenged with bovine type II collagen suppressed clinical and histologic evidence of arthritis, in parallel with diminished levels of TNF-alpha, IL-6, and matrix metalloproteinases (MMP) 3, 9 and 13 in affected tissues. Allelic variation within key domains of RAGE may influence these proinflammatory mechanisms, thereby predisposing individuals to heightened inflammatory responses. A polymorphism of the RAGE gene within the ligand-binding domain of the receptor has been identified, consisting of a glycine to serine change at position 82. Cells bearing the RAGE 82S allele displayed enhanced binding and cytokine/MMP generation following ligation by a prototypic S100/calgranulin compared with cells expressing the RAGE 82G allele. In human subjects, a case-control study demonstrated an increased prevalence of the 82S allele in patients with RA compared with control subjects. These data suggest that RAGE 82S upregulates the inflammatory response upon engagement of S100/calgranulins, and, thereby, may contribute to enhanced proinflammatory mechanisms in immune/inflammatory diseases.

Numerical-experimental method for the validation of a controlled stiffness femoral prosthesis

The aim of this paper is to describe a new numerical-experimental method to determine the stiffness of a conceptual proximal femoral prototype. The methodology consists of the comparison of the numerical and experimental displacement distributions of the prosthesis loaded as a cantilever beam to validate a design concept: controlled stiffness prosthesis. The manufactured prototype used to test the applicability of the numerical-experimental procedure integrates a stiff metal core bonded to a composite material made of an epoxy resin reinforced with carbon-glass braided pre-forms. The prosthesis with an embedded controlled stiffness concept was obtained by varying the geometry of the core with the composite layer thickness.

The influence of vacuum mixing on methylmethacrylate liberation from acrylic cement powder

Polymethylmethacrylate (PMMA) bone cement is a biomaterial used to anchor prostheses during joint replacement surgery. Residual methylmethacrylate monomer (MMA) may be related with the cytotoxic effect of PMMA. The aim of the present paper was to investigate the effect of two different cement mixing methods: hand stirring at atmospheric pressure and under partial vacuum (0.330 and 0.154 bar) on residual monomer liberation in phosphate buffer saline solution from acrylic cement powder. Residual MMA content was determined by high-performance liquid chromatography. Mathematical models were applied to experimental dissolution data revealing that monomer release was significantly reduced in bone cement powder obtained at 0.154 bar vacuum pressure compared to the other mixing conditions. The kinetic models applied are consistent with a simple diffusion mechanism of the monomer from the polymer matrix.

Recessive ataxia with ocular apraxia: review of 22 Portuguese patients

BACKGROUND

The recessive ataxias are a heterogeneous group of neurodegenerative disorders characterized by cerebellar ataxia associated with a number of different neurologic, ophthalmologic, or general signs. They are often difficult to classify in clinical terms, except for Friedreich ataxia, ataxia-telangiectasia, and a relatively small group of rare conditions for which the molecular basis has already been defined.

OBJECTIVES

To study the clinical presentation and to define diagnostic criteria in a group of Portuguese patients with ataxia and ocular apraxia, an autosomal recessive form without the essential clinical and laboratory features of ataxia-telangiectasia.

PATIENTS AND METHODS

We reviewed 22 patients in 11 kindreds, identified through a systematic survey of hereditary ataxias being conducted in Portugal.

RESULTS

Age at onset ranged from 1 to 15 years, with a mean of 4.7 years. The duration of symptoms at the time of last examination varied from 5 to 58 years. All patients presented with progressive cerebellar ataxia, the characteristic ocular apraxia, and a peripheral neuropathy. Associated neurologic signs included dystonia, scoliosis, and pes cavus. Magnetic resonance imaging was performed in 16 patients, all of whom showed cerebellar atrophy.

CONCLUSIONS

Ataxia with ocular apraxia may be more frequent than postulated before, and may be identified clinically using the following criteria: (1) autosomal recessive transmission; (2) early onset (for most patients in early childhood); (3) combination of cerebellar ataxia, ocular apraxia, and early areflexia, with later appearance of the full picture of peripheral neuropathy; (4) absence of mental retardation, telangiectasia, and immunodeficiency; and (5) the possibility of a long survival, although with severe motor handicap.

In vitro release studies of methylmethacrylate liberation from acrylic cement powder

Bone cement or polymethylmethacrylate (PMMA) is commonly used for anchoring cemented prosthesis to the bone. Cytotoxic effect of culture media exposed to PMMA powder may be related with long term problems associated with acrylic cement application, being the monomer (methylmethacrylate) one of the cement's component partly responsible for the cytotoxic effect. The present work reports the studies of monomer release from acrylic bone cement powder under different experimental conditions: setting time of PMMA (in solution and air) and different culture media composition. High-performance liquid chromatography was used for the determination of residual monomer. Mathematical models were applied to experimental dissolution data revealing that monomer release is lightly affected by the studied variables. The monomer release seems to be a surface phenomena, suggesting that the possible actions of monomer will mainly be due to the initial loss of non polymerized monomer rather than to further depolymerization of the already polymerized cement.

Prenatal diagnosis of abdominal enteric duplications

Alimentary tract duplications are rare congenital malformations with few reports of the antenatal sonographic appearance. Early diagnosis is of paramount importance to prevent complications. We present a case of a cystic gastric duplication diagnosed antenatally at 31 weeks' gestation, which was treated successfully. Simultaneously, we review all published cases of prenatally diagnosed enteric duplications.