Investigation of a fatigue failure in a stainless steel femoral plate.

Surgical implants are exposed to severe working conditions and therefore a wide range of failure mechanisms may occur, including fatigue, corrosion, wear, fretting and combinations of them. The mechanical failures of metallic implants may also be influenced by several other factors, including the design, material, manufacturing, installation, postoperative complications and misuse. An 83-year-old patient suffered an oblique femoral shaft fracture due to a fall at home. A stainless steel locking compression plate (LCP) employed in the fracture reduction failed after four months and was sent back to the producer. A second LCP of the same type was implanted and also failed after six months. A failure analysis of the second femoral LCP is performed in this paper. The results demonstrate that poor material quality was decisive to the failure. The chemical analysis revealed a high P content in the steel, which is not in accordance to the standards. A combination of factors lead to LCP fracture and these include: brittle crack initiation due to phosphorus, segregation at grain boundaries, crack propagation due to cyclic loading and final fast fracture favored by the loss of ductility due to cold work.

Depression levels in chronic orofacial pain patients: a pilot study.

The assessment of depressive behaviour in chronic pain patients is especially important, because depression is commonly associated with chronic pain. The aim of this pilot study was to compare depression levels between patients with head and neck cancer pain and temporomandibular disorders (TMD), and to determine whether there is an association between depression levels and chronic pain severity. This study was an observational and sectional study and the sample consisted of 40 patients, uniformly divided into those with chronic orofacial pain related to cancer and those with painful TMD classified with research diagnostic criteria for temporomandibular disorders (RDC/TMD) axis I. Depression levels, pain intensity and severity were assessed with RDC/TMD axis II. The study demonstrated statistically significant differences in depression levels present in the head and neck cancer pain group and the painful TMD group, with the occurrence of a moderate statistically significant correlation between depression levels and chronic pain severity.

The brain-specific activator p35 allows Cdk5 to escape inhibition by p27Kip1 in neurons.

Cell cycle withdrawal in postmitotic cells involves cyclin-dependent kinase (Cdk) inhibitors that repress cell cycle Cdk activity. During mouse neurogenesis, cortical postmitotic neurons are shown here to accumulate high levels of the p27 Cdk inhibitor compared with their progenitor neuroblasts. Elevated p27 levels in staged embryo brain extracts correlate with p27 binding to Cdk2, and Cdk inactivation. Yet, Cdk5, which is associated with the noncyclin activator p35 in neurons, remains active in the presence of high p27 levels. Both in vitro and in vivo, p27 and related inhibitors can recognize a cyclin D-Cdk5 complex but not a p35-Cdk5 complex. The results indicate that the choice of activator determines the susceptibility of Cdk5 to p27 and related Cdk inhibitors, and thus its ability to act in postmitotic cells.

Metodologia de avaliaçäo cardiológica do atleta normal e cardiopata / Methodology for cardiac evaluation of normal athletes and with heart disease

O exame cardiológico do atleta tem, entre seus principais objetivos, a detecçäo de alguma cardiopatia desconhecida, que poderia levar a problemas futuros, com a manutençäo da prática esportiva. O cardiologista deve estar a par das alteraçöes que podem ser encontradas no "coraçäo do atleta", para identificar anormalidades da propedêutica potencialmente importantes, bem como conhecer como as alteraçöes habituais regridem quando o indivíduo abandona a atividade esportiva. Säo discutidos os exames mínis que deve ser realizados na avaliaçäo do atleta, tendo em vista a dificuldade de obtençäo das condiçöes tecnológicas ideais. Entretanto, säo abordados também exames mais sofisticados, que seräo realizados de acordo com a necessidade de cada caso.

Winged helix transcription factor BF-1 is essential for the development of the cerebral hemispheres.

We generated mice with a null mutation of the forebrain-restricted transcription factor BF-1 to examine its function in brain development. Heterozygous animals have an apparently normal phenotype. Homozygous null BF-1 mutants die at birth and have a dramatic reduction in the size of the cerebral hemispheres. The development of the ventral telencephalon is more severely affected than that of the dorsal telencephalon. Telencephalic neuroepithelial cells are specified in the BF-1 mutant, but their proliferation is reduced. Dorsal telencephalic neuroepithelial cells also differentiate prematurely, leading to early depletion of the progenitor population. These results suggest that BF-1 controls the morphogenesis of the telencephalon by regulating the rate of neuroepithelial cell proliferation and the timing of neuronal differentiation.

Estimate of the genetic divergence between inbred Dahl salt-sensitive and salt-resistant rats.

OBJECTIVE: The genetic divergence of inbred Dahl salt-sensitive (SS/Jr) rats from inbred Dahl salt-resistant (SR/Jr) rats and various other inbred strains was measured. DESIGN: Structural differences in DNA between strains were evaluated. METHODS: Genetic variants were sought (1) by restriction fragment length polymorphism (RFLP) analysis, using 19 DNA probes, (2) by the polymerase chain reaction around microsatellites and (3) by DNA sequencing. RESULTS: It was estimated that 1 in 1532 bases of DNA were different between the SS/Jr and SR/Jr strains. In comparing SS/Jr and SR/Jr rats, it was also observed that one DNA probe in 10 will yield multiple RFLP, presumably as the result of large insertion/deletion events. A comparison of SS/Jr rats with seven other inbred strains showed that the percentage of loci that carry alleles different from SS/Jr rats varies from about 23% for Albino Surgery rats to 71% for Brown Norway rats. CONCLUSIONS: Although the SR/Jr strain is an appropriate contrasting strain for the genetic analysis of hypertension in SS/Jr rats, a genetic analysis involving crosses of SS/Jr rats and unrelated inbred strains is also likely to be useful in identifying genes that cosegregate with blood pressure because more informative genetic markers will be available than in a cross of SS/Jr with SR/Jr rats.