Effects of doxorubicin administration on bone strength and quality in sedentary and physically active Wistar rats

Summary

Doxorubicin (DOX) is used in pediatric cancer treatment. This study assessed the effects of 7 weeks of DOX and 10-week recovery on bone quality and biomechanical properties in sedentary and exercised Wistar rats. DOX decreases femur diaphysis radial growth and biomechanical properties. Some of these DOX effects were aggravated by exercise.

Introduction

Bone growth in pre-pubertal years critically influences adult fracture risk. DOX is widely used in the treatment of pediatric cancers, but there is limited evidence on its potential negative effects on bone growth. Exercise improves bone growth in children, but there is no evidence if it protects against DOX-induced bone toxicity. This study investigates the early and intermediate effects of a 7-week course of DOX on bone histomorphometry and strength in sedentary and exercised growing animal models.

Methods

Sixty-eight male Wistar rats (8 weeks) were treated with DOX (2 mg kg^?1) or vehicle for 7 weeks and afterward housed in standard cages or in cages with a running wheel and killed 2 or 10 weeks after last DOX administration. Femurs and blood were collected for assaying geometry, trabecular microarchitecture (histology), biomechanical properties (three-point bending and shearing of the femoral neck), bone calcium content and density (atomic absorption spectroscopy), and bone turnover markers (ELISA).

Results

DOX treatment reduced the femur diaphysis radial growth, with DOX-treated animals having a lower tissue area, cortical area, cortical thickness, and moment of inertia. DOX also decreased distal femur trabecular bone volume and trabecular number and increased trabecular separation. Femur diaphysis stiffness and maximum load were also reduced in past DOX-treated animals. Exercise was shown to worsen the effects of past DOX treatment on the femur diaphysis mechanical properties.

Conclusion

DOX negatively affects bone geometry, trabecular microarchitecture, and femur mechanical properties in growing Wistar rats. Exercise further aggravates the detrimental effects of past DOX treatment on bone mechanical properties.

     

Validity and reliability of the Disabilities of Arm,Shoulder, and Hand scale in dental students: A transnational study

This study aimed to evaluate the validity and reliability of the Disabilities of Arm, Shoulder, and Hand (DASH) scale in Brazilian and American dental students and assess the influence of demographic variables on disability in them. A cross-sectional observational study was conducted with a nonprobabilistic sample. The sample was composed of students of both genders from the School of Dentistry of Araraquara, State University of São Paulo (UNESP) (n = 288), and students from Stony Brook University, New York, NY, USA (n = 149). The disabilities of the upper limbs were estimated using the DASH scale. The samples were characterized by collecting information on gender, academic year, and sports and work activities. The refined bifactorial model presented goodness-of-fit indices for both countries. There was a significant effect of the variables gender and academic year for the Brazilian sample and the variable sports practices for the American sample. The refined bifactorial model was valid and reliable for the Brazilian and American populations. In this model, the removal of item 17 for the Brazilian sample and items 3, 13, and 23 for the American sample was necessary. Demographic variables such as gender, academic year, and sports practice contributed significantly to the level of disability in the study populations.     

Translation,Adaptation and Validation of Rapid Geriatric Assessment to the Brazilian Context

Objectives

Translate, cross-culturally adapt and validate the Rapid Geriatric Assessment (RGA) for Brazilian community-dwelling adults.

Design

Cross-sectional study, using a quantitative approach.

Setting

Urban population from the city of São Carlos, located in the interior of São Paulo State, Brazil. Participants: 148 individuals aged 60 or over.

Measurements

Participants were assessed using the RGA, Fried Frailty Phenotype, International Physical Activity Questionnaire - long version, Addenbrooke´s Cognitive Exam - Revised Version, Mini Nutritional Assessment, short Form - 36, EuroQol 5-Dimension, Geriatric Depression Scale - short version, in addition to performing Dual Energy X-ray Absorptiometry to diagnose sarcopenia, according to the criteria established by the European Working Group on Sarcopenia in Older People.

Results

In the translation and adaption process of the RGA, steps recommended by the literature were followed: initial translation, synthesis of translations, backward translation, evaluation from the panel of judges, and pre-test. When evaluating the psychometric properties of the scale, satisfactory reliability (internal consistency and stability) and validity (content, concurrent criterion and convergent, divergent and discriminant construct) were verified.

Conclusion

The Brazilian version of the RGA is reliable and valid, and can be used in the Brazilian context to evaluate the elderly population.

     

Multiplex PCR strategy for subtyping the staphylococcal cassette chromosome mec type IV in methicillin-resistant Staphylococcus aureus: 'SCCmec IV multiplex'

OBJECTIVES: To develop and validate a new multiplex PCR strategy for subtyping SCCmec type IV methicillin-resistant Staphylococcus aureus (MRSA) strains-SCCmec IV multiplex PCR. METHODS: Seven primer pairs were designed to detect the ccrB allotype 2 (internal positive control), the five polymorphic J1 regions described so far for SCCmec type IV and the new J1 region specific for EMRSA-15. Primer sets were tested for specificity and robustness with prototype strains for each subtype of SCCmec type IV. The multiplex PCR conditions were optimized in a trial-error approach. RESULTS: The seven prototype strains for the earlier described subtypes of SCCmec type IV and the EMRSA-15 prototype strain were correctly characterized by our strategy. Moreover, 13 diverse SCCmec type IV strains could be assigned to a subtype of SCCmec type IV and 5 EMRSA-15 strains were assigned to the new subtype IVh. One strain could not be assigned to an SCCmec type IV subtype because of the absence of amplification of the specific J1 region. CONCLUSIONS: This new strategy, based on a single multiplex PCR reaction, is adequate for the rapid assignment of all major subtypes of SCCmec type IV described so far and also the new subtype IVh characteristic of EMRSA-15. This strategy complements well the previously described multiplex PCR assay for the rapid assignment of SCCmec types.     

In vitro inhibition of bacterial growth using different dental adhesive systems

OBJECTIVES: This study evaluated the antibacterial potential of four different adhesive systems. METHODS & MATERIALS: Gluma Comfort Bond + Desensitizer, Gluma Comfort Bond, iBond and One-Up Bond F were tested against Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The inhibition of growth by calibrated preparations was quantified by the measurement of zones of inhibition on bacterial lawns. Bactericidal activity was determined as reductions in recoverable colony-forming units in bacterial suspensions exposed to test preparations. RESULTS: All the preparations exhibited detectable zones of inhibition for all target bacteria through six months. When the bactericidal action was evaluated, all the materials were able to kill all the tested bacteria when tested immediately after polymerization. After one week of aging, iBond was the only material that continued to kill all of the test strains.