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.

Papillary muscles and tendinous cords of the right ventricle of the human heart: morphological characteristics.

A series of 79 normal human hearts was studied focusing on the morphological characteristics of the papillary muscles of the right ventricle and their tendinous cords (chordae tendineae). The number, incidence, length and shape of the anterior, septal and posterior papillary muscles were observed. The tendinous cords attached to each papillary muscle were counted at their origin. The papillary muscles and the tendinous cords were measured in situ and after the removal of the right atrioventricular valve (tricuspid valve). The anterior and posterior papillary muscles (apm, ppm) were present in 100% of the cases. The septal papillary muscle (spm) was absent in 21.5% of the hearts. The apm presented 1 head in 81% and 2 heads in 19%; it was 19.16 mm in length. The spm was one-headed in 41.7% and presented two heads in 16.5%; the presence of a 3 and 4 heads appeared in 12.7% and 7.6% respectively; the spm was 5.59 mm in length. The ppm had 1 head in 25.4%, 2 heads in 46.8%, 3 heads in 21.5% and 4 heads in 6.3% of the cases; it was 11.53 mm in length. Tendinous cords (TC) varied as follows: from 1 to 11 TC originated in the apm (mean 4.74); from 1 to 8 TC originated in the ppm (mean 2.67) and from 1 to 5 TC originated in the spm (mean 1.77).

The cardiac ganglia: cellular and molecular aspects.

The cardiac ganglia are distributed in different regions of the atria of a number of mammalian species, surrounding the SA node, around the roots of the venae cava and pulmonary veins, interatrial septum, in the proximity of the AV node and in the auricular appendages. A typical cardiac ganglion consists of neurons, satellite cells and SIF cells. The mammalian cardiac ganglia contain unipolar, bipolar and multipolar neurons with differing dimensions and shapes. The neurons and satellite cells of the cardiac ganglia originate from neural crest cells that migrate to the heart. Upon arriving in the outflow tract the cells segregate into parasympathetic neurons and supporting cells to form the cardiac ganglia. The sympathetic innervation of the heart arises from the cervicothoracic sympathetic chains and is derived from the trunk neural crest. The ultrastructural development of the cardiac ganglia in the chicken can be divided into three phases: (1) migration and aggregation of neuroblasts on days 3.5-5; (2) differentiating ganglia, days 5-10; (3) maturing ganglia, days 11 to hatching. The development of cholinergic mechanisms precedes that of adrenergic mechanisms. As a consequence the parasympathetic-cholinergic control becomes functional and plays a role in cardiac function earlier than the sympathetic-adrenal neural control. The genes that may control the development of certain components of the cardiac ganglia are described.

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.

Genetic analysis of alpha 2-adrenergic receptors and blood pressure using Dahl salt-sensitive rats.

OBJECTIVE: To evaluate the role of alpha 2-adrenergic receptors in genetic hypertension by cosegregation analysis using Dahl rats. DESIGN: Inbred Dahl salt-sensitive (SS/Jr) rats were crossed with inbred Dahl salt-resistant (SR/Jr) rats; also, SS/Jr rats were crossed with several control strains, and large F2 populations were subsequently produced from each cross. All F2 populations were raised on a high-salt diet. The rats were genotyped, where possible, at the loci for three different subtypes of alpha 2-adrenergic receptors designated as classes I, II and III. The blood pressures of the rats classified by genotype at each alpha 2-adrenergic receptor subtype locus were compared using analysis of variance. METHODS: Genomic clones of three classes of alpha 2-adrenergic receptors were isolated from genomic lambda-phage libraries of SS/Jr or SR/Jr rat strains, or both, by screening with complementary DNA for human alpha 2-adrenergic receptors. Fragments of the rat genomic clones obtained were used for genotyping by restriction fragment length polymorphism. Also, cloned genomic DNA flanking the alpha 2-adrenergic receptors and containing microsatellites was sequenced; genotyping at informative microsatellite markers was performed using the polymerase chain reaction. Two of the three classes of rat alpha 2-adrenergic receptors were localized to rat chromosomes by linkage analysis or using a panel of mouse-rat hybrid somatic cell lines. RESULTS: Rat alpha 2-adrenergic receptor classes I and III genes were assigned to rat chromosomes 14 and 3, respectively. These correspond to alpha 2-adrenergic receptor genes on human chromosomes 4 and 2, respectively. Extensive cosegregation analysis, involving five alleles in six segregating populations for class I alpha 2-adrenergic receptors, yielded no evidence of an effect of these loci on blood pressure. Classes II and III alpha 2-adrenergic receptors could each be tested in only one population and there was no evidence for an effect of either receptor gene on genetic differences in blood pressure. The dopamine-1B receptor was closely linked to the class I alpha 2-adrenergic receptor on rat chromosome 14. Thus, the negative cosegregation of the class I receptor with blood pressure applies equally to the dopamine-1B receptor. CONCLUSIONS: Genetic analysis in segregating populations involving crosses of inbred Dahl salt-sensitive rats with five other strains provides no evidence for a genetic effect of class I alpha 2-adrenergic receptors, or of the dopamine-1B receptor, on blood pressure. Classes II and III alpha 2-adrenergic receptors also failed to cosegregate with blood pressure but, because only limited testing was possible with the classes II and III receptors, this negative result is not definitive.

Cell-cell interactions influence survival and differentiation of purified Purkinje cells in vitro.

To determine the role of cell-cell interactions in Purkinje cell survival and dendritic differentiation, perinatal mouse Purkinje cells were purified, and their development was analyzed in vitro. In isolation at low density, Purkinje cell survival was poor, improved by neuronal contacts, either with purified granule neurons or with Purkinje cells themselves. Moreover, coculture with specific cell populations led to widely different degrees of Purkinje cell differentiation. Purified Purkinje cells cultured alone or with an inappropriate afferent, the mossy fibers, did not progress beyond immature forms. With astroglia, Purkinje cells had thin smooth processes. Proper Purkinje cell differentiation was driven only by coculture with granule cells, resulting in dendrites with spines receiving synapses. These results suggest that Purkinje cell differentiation is regulated by local epigenetic factors, provided in large part by the granule neuron.

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.

Specificity of a target cell-derived stop signal for afferent axonal growth.

With a novel model culture system in which afferents are co-cultured with purified populations of target neurons, we have demonstrated that a target cell within the central nervous system (CNS), the cerebellar granule neuron, poses a "stop-growing signal" for its appropriate afferents, the mossy fibers. To ask whether this stop signal is afferent specific, we co-cultured granule neurons with another cerebellar afferent system, the climbing fibers from the inferior olivary nuclei, which normally contact Purkinje neurons, and with retinal ganglion cell afferents, which never enter the cerebellum. Granule neurons do not pose a stop signal to either of these afferents. In contrast to pontine mossy afferents that grow well on laminin and showed reduced outgrowth on granule neurons, both olivary and retinal fibers displayed similar growth on laminin alone or on granule neurons. In addition, each afferent showed different degrees of fasciculation and growth cone morphology on laminin. Thus, the growth arrest signal sent by granule neurons is specifically recognized by their appropriate afferents. Moreover, these three types of afferents exhibit varying growth patterns on the same noncellular and cellular substrates, implicating distinct molecular characteristics of growth regulation for different classes of neurons that would contribute to specificity of synapse formation.

Variations of the blood supply of the human conus arteriosus.

The conus arteriosus was divided into right and left halves and each half was subdivided into 3 portions: superior, middle and inferior. The study of the blood supply of the conus was performed in 8O human hearts. The results showed that the sternocostal wall of the conus arteriosus may be supplied by the arteria coni arteriosi but, more frequently by branches of the right and left coronary arteries. The most frequent branches supplying the conus arteriosus were the ramus anterior ventriculi dextri medialis and lateralis (85%), ramus coni arteriosi dexter (51.2%), ramus anterior ventriculi dextri medius I (47.5%), ramus anterior ventriculi dextri intermedius (41.2%), ramus coni arteriosi sinister (40%) and ramus anterior ventriculi dextri superior I (38.7%).

The relationship between the directions of myocardial bridges and of the branches of the coronary arteries in the human heart.

The variations of the direction of the myocardial bundles of the bridges over coronary arteries and branches were studied in relation to the direction of the vessels over which they are found. The investigation was performed on 82 hearts of individuals whose death was accidental and unrelated to cardiac disease. The hearts were obtained from cadavers of individuals of either sex and different racial groups, whose age ranged from 7 to 68 years. The angle between the direction of the musculature and of the vessels may explain why in some cases there is no change in the structure of the "pontine portion" of the wall.

Normally unused positional cues guide ectopic afferents in the leech CNS.

Central projections from peripheral sensory neurons segregate into distinct, ventrally positioned longitudinal tracts within the segmental ganglia of the leech Hirudo medicinalis. As documented here, there is an additional tract in the neuropils of the fifth and sixth body ganglia, located at the lateral margin and formed by afferent axons (the "sex afferents") originating from sensory neurons located in the male and female genitalia. Ablation of the genitalia results in the complete absence of this additional tract. We asked (1) whether segmental differences exist in the distribution of pathway cues available to the sex afferents, and (2) whether central pathway selection by these axons is specific. We transplanted the primordia of the male genitalia to several ectopic positions posterior to the sixth body segment and labeled the ectopic sex afferents in order to examine their paths in the CNS. In about 50% of the experimental animals, afferent axons originating in the transplanted tissue segregated into a distinct lateral fiber bundle within the neuropil of a nearby ganglion, in a position corresponding to their normal one in the sex ganglia. The sex afferents therefore find their normal pathways even in the ganglia of inappropriate segments, although these pathways are not used by any other afferents in these ganglia. We propose, therefore, that the positional cues employed by afferent axons to select appropriate pathways in the ganglionic neuropil are expressed in all segments of the leech CNS, regardless of whether such cues are normally used by afferent axons in each segment.

Types of division of the left coronary artery and the ramus diagonalis of the human heart.

The surgical, clinical and radiological importance of the diagonal artery in the human heart and the extreme variability in its description prompted us to undertake its study. The investigation was performed in 150 hearts, dissected after injection of colored substance in the coronary arteries. The following results were obtained: The left coronary artery presented 3 types of division: bifurcation (54.7%), trifurcation (38.7%) and quadrifurcation (6.7%); the latter 2 patterns produced a diagonal artery. The trunk of the left coronary artery bifurcated more frequently in hearts of female Caucasians (57.1%) and male Caucasians (54.9%). It trifurcated more frequently (60%) in hearts of female non-Caucasians. The ramus diagonalis was found in 45.3% of the hearts. The incidence of a ramus diagonalis did not differ significantly between male Caucasians (45%), male non-Caucasians (42.8%) and female Caucasians (37%). However, it occurred more frequently in female non-Caucasians (66.5%). The length of the ramus diagonalis varied from 20.1 to 50 mm (79.3%) and its relative length varied from 21 to 50% of the length of the left ventricle (75.3%). The ramus diagonalis was classified as short, medium and long types, the former 2 types were most frequent.

The membranous portion of the interventricular septum and its relationship with the aortic valve in humans.

Investigation of the membranous portion of the interventricular septum (MPIS) and its relationship with the aortic valve was performed in 32 human hearts of adult individuals (19 Caucasians and 11 non-Caucasians). With transillumination of the MPIS the specimens were photographed and 35 mm slices obtained. These were digitized into Apple Macintosh II using a Dage Model 68 video camera and a Data Translations DT 2255 frame grabber. The areas and the distances were traced manually, using the NIH Image program (Wayne Rasband, NIH, Research Services Branch, NIHM). The following forms of MPIS were found: oval (31.3%), triangular (28.1%), quadrangular (18.8%), circular (15.6%) and semilunar (6.2%); its surface area varied from 5.65 mm2 to 142.63 mm2 (mean 48.82 +/- 29.17 mm2). The superior border of the MPIS was in close relationship with the aortic valve, and its upper part was usually (41%) in direct continuity with the attachments of both right (RAC) and posterior (PAC) aortic cusps, or with PAC (34%) or RAC (6%) only. Rarely (19%) the MPIS lay below the attachments of both cusps. The distance between the MPIS superior border and the attachment of the RAC was not greater than 5.89 mm (mean 1.69 mm +/- 1.9 mm). The distance between the superior border of the MPIS and the attachment of the PAC was not greater than 5.63 mm (mean 0.77 +/- 1.49 mm). Differences between sex, race and age groups were not statistically significant.

Atrioventricular and ventriculoatrial branches of the coronary arteries in human hearts.

Atrioventricular (AV) and ventriculoatrial (VA) branches of the coronary arteries are vessels which supply simultaneously atrial and ventricular walls by means of recurrent rami. The terminology indicates the name of the main vessel followed by the name of the recurrent vessel both combined in an adjective. These branches establish a vascular 'suture' across the coronary sulcus in front (superficially to) or behind (deeply to) the trunks of the right coronary artery and of the left coronary artery (circumflex artery). The AV and VA branches, found in 95% of 40 human hearts, should be considered a normal characteristic of the coronary circulation and an important anatomical factor for the clinical interpretation of pathological cardiac phenomena.

Anatomical variations of the abducent nerve in humans.

Anatomical variation of the nervus abducens in human encephali were found and described. They consisted of (1) an unusual trifurcation of the abducent nerve, limited to the extradural portion of the neural trunk (1.4% of the cases) and (2) the duplicity (11.1%) of the neural trunk, starting before reaching the orbit and ending before reaching the m. rectus lateralis. The possibility of correlating these variations with clinical aspects and forensic interpretations is mentioned.

Peripheral organs control central neurogenesis in the leech.

Interactions between developing nerve centres and peripheral targets are known to affect neuronal survival and thus regulate the adult number of neurons in many systems. Here we provide evidence that peripheral tissues can also influence cell numbers by stimulating the production of neurons. In the leech Hirudo medicinalis, there is a population of several hundred neurons that is found only in the two segmental ganglia that innervate the genitalia and which seem to be added gradually during post-embryonic maturation. By monitoring 5-bromo-2'-deoxyuridine incorporation immunohistochemically, we have now determined that these neurons are actually born late in embryogenesis, well after all other central neurons are born and after efferent and afferent projections are established between these ganglia and the periphery. Ablation of the male genitalia early in embryogenesis, or evulsion of the nerves that connect them to the ganglia, prevent the birth of these neurons. However, they fail to appear ectopically when male genitalia are transplanted to other segments, despite innervation by local ganglia. We conclude that the generation of the late-appearing neurons depends on a highly localized signal produced by the male genitalia, to which only the ganglia that normally innervate these organs have the capacity to respond.