Iliac auricular surface morphofunctional study in felidae

Felids show remarkable phenotypic similarities and are conservative in behavioral and ecological traits. In contrast, they display a large range in body mass from around 1kg to more than 300kg. Body size and locomotory specializations correlate to skull, limb and vertebral skeleton morphology. With an increase in body mass, felids prey selection switches from small to large, from using a rapid skull or spine lethal bite for small prey, to sustained suffocating bite for large prey. Dietary specialization correlates to skull and front limbs morphology but no correlation was found on the spine or on the hind limb. The morphology of the sacroiliac junction in relation to ecological factors remained to be described. We are presenting a study of the overall shape of the iliac auricular surface with qualitative and quantitative analyses of its morphology. Our results demonstrate that body mass, prey selection, and bite type, crucially influence the auricular surface, where no significant effect of locomotor specialization was found. The outline of the surface is significantly more elevated dorso-caudally and the joint surface shows an irregular W-shape topography in big cats whereas the surface in small cats is smoother with a C-shape topography and less of an elevated ridge. Biomechanically, we suggest that a complex auricular surface increases joint stiffness and provides more support in heavier cats, an advantage for subduing big prey successfully during a sustained bite.

Clinical and immunological characteristics of type 1 diabetes mellitus in a northwestern Colombian population

We underwent a project aimed to define the clinical and immunological characteristics of type 1 diabetes (T1D) in a Colombian population. This was a multicenter and cross-sectional study. Patients were systematically interviewed and their medical records reviewed, using a questionnaire that sought information about demographic, clinical and immunological characteristics. Glutamic acid decarboxylase antibodies (GADA), tyrosine phosphatase antibodies (IA-2A) and insulin antibodies (IAA) were examined by radioimmunoassay. There were 107 patients with T1D. Male:female ratio was 1:1. Half of the patients developed diabetes ketoacidosis at onset. GADA, IA-2A, and IAA were detected in 45%, 40%, and 69% of the cases, respectively. GADA positive patients were older and had a less duration of disease than patients without these autoantibodies (p<0.01). Association between breast feeding with the presence of antibodies or clinical characteristics was not observed. The results highlight some differences of T1D expression according to geographic location and ethnicity. Differences in age at onset and clinical variables may point to an environmental factor or deficient access to health care system. Genetic studies underway will provide important information in this population. These results might help to define public health policies in our population to improve T1D diagnosis, patients' quality of life and their outcome.

Estrogen receptor-alpha and -beta are expressed throughout postnatal development in the rat and rabbit growth plate

Estrogen regulates skeletal growth and promotes epiphyseal fusion. To explore the mechanisms underlying these effects we investigated the expression of estrogen receptor-alpha (ERalpha) and -beta (ERbeta) in rat and rabbit growth plates during postnatal development, using immunohistochemistry. Immunoreactivity for ERalpha and ERbeta was observed in resting zone and proliferative zone chondrocytes at all ages studied for both rat (7, 14, 28 and 70 days of age) and rabbit (1, 7, 28 and 120 days of age). In the rat distal humerus and the rabbit proximal tibia, expression of both receptors in the hypertrophic zone was minimal at early ages, increasing only at the last time point prior to epiphyseal fusion. Expression was rarely seen in the hypertrophic zone of the rat proximal tibia, a growth plate that does not fuse until late in life. Therefore, we conclude that ERalpha and ERbeta are both expressed in the mammalian growth plate. The temporal and anatomical pattern suggests that ER expression in the hypertrophic zone in particular may play a role in epiphyseal fusion.

Glucocorticoid excess during adolescence leads to a major persistent deficit in bone mass and an increase in central body fat

Endogenous Cushing's syndrome (CS) in children causes growth retardation, decreased bone mass, and increased total body fat. No prospective controlled studies have been performed in children to determine the long-term sequelae of CS on peak bone mass and body composition. A 15-year-old girl with Cushing disease (CD), and her healthy identical co-twin, were followed for 6 years after the CD was cured. At the 6-year follow-up both twins had areal bone mineral density (BMD) and body composition determined by dual-energy X-ray absorptiometry (DXA) and three-dimensional quantitative computed tomography (3DQCT). Z scores for height, weight, and body mass index (BMI) were -2.3, -0.8 and 0.2, and 1.2, 0.2, and -0.6, in the twin with CD and her co-twin, respectively. In the twin with CD, areal BMD and bone mineral apparent density (BMAD) at different sites varied from 0.7 to 3 SD below her co-twin. Volumetric lumbar spine bone density Z score was -0.75 and 1.0, and total body, abdominal visceral, and subcutaneous fat (%) was 42, 10, and 41 versus 26, 4, and 17 in the twin with CD and her co-twin, respectively. The relationship between total body fat and L2-L4 BMAD was inverse in the twin with CD (p < 0.05), which by contrast in her co-twin was opposite and direct (p < 0.001). In the twin with CD, despite cure, there was a persistent deficit in bone mass and increase in total and visceral body fat. These observations suggest that hypercortisolism (exogenous or endogenous) during adolescence may have persistent adverse effects on bone and fat mass.

Effects of estrogen on growth plate senescence and epiphyseal fusion

Estrogen is critical for epiphyseal fusion in both young men and women. In this study, we explored the cellular mechanisms by which estrogen causes this phenomenon. Juvenile ovariectomized female rabbits received either 70 microg/kg estradiol cypionate or vehicle i.m. once a week. Growth plates from the proximal tibia, distal tibia, and distal femur were analyzed after 2, 4, 6, or 8 weeks of treatment. In vehicle-treated animals, there was a gradual senescent decline in tibial growth rate, rate of chondrocyte proliferation, growth plate height, number of proliferative chondrocytes, number of hypertrophic chondrocytes, size of terminal hypertrophic chondrocytes, and column density. Estrogen treatment accelerated the senescent decline in all of these parameters. In senescent growth plates, epiphyseal fusion was observed to be an abrupt event in which all remaining chondrocytes were rapidly replaced by bone elements. Fusion occurred when the rate of chondrocyte proliferation approached zero. Estrogen caused this proliferative exhaustion and fusion to occur earlier. Our data suggest that (i) epiphyseal fusion is triggered when the proliferative potential of growth plate chondrocytes is exhausted; and (ii) estrogen does not induce growth plate ossification directly; instead, estrogen accelerates the programmed senescence of the growth plate, thus causing earlier proliferative exhaustion and consequently earlier fusion.

Regulation of growth plate chondrogenesis by bone morphogenetic protein-2

Bone morphogenetic proteins (BMPs) regulate embryonic skeletal development. We hypothesized that BMP-2, which is expressed in the growth plate, also regulates growth plate chondrogenesis and longitudinal bone growth. To test this hypothesis, fetal rat metatarsal bones were cultured for 3 days in the presence of recombinant human BMP-2. The addition of BMP-2 caused a concentration-dependent acceleration of metatarsal longitudinal growth. As the rate of longitudinal bone growth depends primarily on the rate of growth plate chondrogenesis, we studied each of its three major components. BMP-2 stimulated chondrocyte proliferation in the epiphyseal zone of the growth plate, as assessed by [(3)H]thymidine incorporation. BMP-2 also caused an increase in chondrocyte hypertrophy, as assessed by quantitative histology and enzyme histochemistry. A stimulatory effect on cartilage matrix synthesis, assessed by (35)SO(4) incorporation into glycosaminoglycans, was produced only by the highest concentration of BMP-2. These BMP-2-mediated stimulatory effects were reversed by recombinant human Noggin, a glycoprotein that blocks BMP-2 action. In the absence of exogenous BMP-2, Noggin inhibited metatarsal longitudinal growth, chondrocyte proliferation, and chondrocyte hypertrophy, which suggests that endogenous BMPs stimulate longitudinal bone growth and chondrogenesis. We conclude that BMP-2 accelerates longitudinal bone growth by stimulating growth plate chondrocyte proliferation and chondrocyte hypertrophy.

Leptin secretion in Cushing's syndrome: preservation of diurnal rhythm and absent response to corticotropin-releasing hormone

The normal inverse relationship between leptin and cortisol is lost in chronic hypercortisolism. We studied this apparent dysregulation in patients with Cushing's syndrome to investigate 1) the effect of chronic hypercortisolemia on the circadian rhythm of leptin secretion, 2) the response of leptin after administration of CRH, and 3) the short term effect of curative surgery on leptin. The preoperative morning leptin concentration was 54.2 +/- 8.1 ng/mL, and the nighttime value was 68.6 +/- 9.8 ng/mL, reflecting a mean rise of 32.8 +/- 7.6%, similar to the nocturnal increase observed in normal subjects. By contrast, cortisol's diurnal variation (21.8 +/- 1.7 vs. 16.9 +/- 1.1 mg/dL) was blunted. In women, but not men, body mass index correlated with leptin (P = 0.001). Preoperative ACTH and cortisol (both P < 0.0001), but not leptin levels increased after CRH. Ten days after surgery, basal cortisol values were subnormal (1.1 +/- 0.6 mg/dL), but leptin levels remained unchanged and did not increase after CRH. Body mass index and insulin also remained unchanged. Insulin, but not age, urinary free cortisol, or plasma cortisol correlated with leptin (P < 0.05). In summary, patients with Cushing's syndrome have moderately elevated leptin levels that maintain an intact circadian rhythm but do not respond to acute or subacute alterations of cortisol.

Determinants of spatial polarity in the growth plate

Growth of long bones occurs at the growth plate, a layer of cartilage that separates the epiphysis from the metaphysis. Growth plate exhibits spatial polarity. Proliferative chondrocytes undergo terminal differentiation when they approach the metaphyseal, but not the epiphyseal, border of the growth plate. The adjacent bone also exhibits spatial polarity. Metaphyseal, but not epiphyseal, blood vessels and bone cells invade the adjacent growth plate, remodeling it into bone. As a result, the metaphysis, but not the epiphysis, elongates over time. To determine whether cartilage polarity determines bone polarity and/or whether bone polarity determines cartilage polarity, rabbit distal ulnar growth plates were excised, inverted, and reimplanted in their original beds. Thus, cartilage polarity was inverted relative to bone polarity. Histological examination showed that the inverted cartilage polarity was maintained over time. In contrast, the polarity of the adjacent bone reversed after surgery, to match that of the cartilage. Blood vessel and bone cell invasion ceased in the metaphysis and arose in the epiphysis. Longitudinal bone growth (measured with weekly radiographs) occurred at the epiphyseal, not at the metaphyseal, surface of the growth plate. We conclude that the polarity of growth plate cartilage is determined by intrinsic factors. The cartilage polarity then determines the polarity of the adjacent bone and, consequently, the functional polarity of longitudinal bone growth.

Treatment of persistent myoclonic tardive dystonia with verapamil

A dramatic improvement in a patient with tardive dystonia was obtained with verapamil after the failure of other medicines. The use of verapamil or other calcium-channel blockers should be considered when treating drug-induced movement disorders.