Effects of a moderate exercise regimen on development and puberty attainment of beef heifers reared in drylots at a high stocking density.

This experiment evaluated growth, physiological responses, and puberty attainment in beef heifers reared in drylots with a high stocking density, and provided or not with a moderate exercise regimen. A total of 180 heifers (75% Angus × 25% Brahman) were used in this experiment replicated over 2 yr. Each year, 90 heifers were ranked by age (264 ± 1 d) and body weight (BW on day -3; 200 ± 2 kg) on day 0, and assigned to a) one of six drylot pens (10 × 14 m pens; 10 heifers per pen) with a stocking density of 14 m2/heifer (DENS), or b) one of three pastures (2-ha pastures; 10 heifers per pasture) with a stocking density of 2,000 m2/heifer (CON).

Seroprevalence of porcine reproductive and respiratory syndrome virus on swine farms in a tropical country of the Middle Americas: the case of Costa Rica.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes significant economic losses to the swine industry worldwide. Little is known regarding the epidemiology of this infection in tropical countries. To address this problem in Costa Rica, a seroepidemiological study was carried out in two phases.

Analysis of ORF5 sequences of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) circulating within swine farms in Costa Rica.

Background: Worldwide, Porcine Reproductive and Respiratory Syndrome (PRRS) is among the diseases that cause the highest economic impact in modern pig production. PRRS was first detected in Costa Rica in 1996 and has since then severely affected the local swine industry. Studies of the molecular characterization of circulating strains, correlation with clinical records, and associations with pathogens associated with Porcine Respiratory Disease Complex (PRDC) have not been done in Costa Rica.

Rumen and Serum Metabolomes in Response to Endophyte-Infected Tall Fescue Seed and Isoflavone Supplementation in Beef Steers.

Fescue toxicosis impacts beef cattle production via reductions in weight gain and muscle development. Isoflavone supplementation has displayed potential for mitigating these effects. The objective of the current study was to evaluate isoflavone supplementation with fescue seed consumption on rumen and serum metabolomes.

Specific networks of plasma acute phase reactants are associated with the severity of chronic obstructive pulmonary disease: a case-control study.

A detailed understanding of the intricate relationships between different acute phase reactants (APRs) in chronic obstructive pulmonary disease (COPD) can shed new light on its clinical course. In this case-control study, we sought to identify the interaction networks of a number of plasma APRs in COPD, with a special focus on their association with disease severity. COPD cases and healthy smoking controls (3:1 ratio) were recruited in our outpatient pulmonary clinic.

An adaptive jitter mechanism for reactive route discovery in sensor networks.

This paper analyses the impact of jitter when applied to route discovery in reactive (on-demand) routing protocols. In multi-hop non-synchronized wireless networks, jitter--a small, random variation in the timing of message emission--is commonly employed, as a means to avoid collisions of simultaneous transmissions by adjacent routers over the same channel. In a reactive routing protocol for sensor and ad hoc networks, jitter is recommended during the route discovery process, specifically, during the network-wide flooding of route request messages, in order to avoid collisions.

Sex specificity of ventral anterior cingulate cortex suppression during a cognitive task.

Ventral anterior cingulate cortex (vACC) is a highly interconnected brain region considered to reflect the sometimes competing demands of cognition and emotion. A reciprocal relationship between vACC and dorsal ACC (dACC) may play a role in maintaining this balance between cognitive and emotional processing. Using functional MRI in association with a cognitively-demanding visuospatial task (mental rotation), we found that only women demonstrated vACC suppression and inverse functional connectivity with dACC.

The relation between computerized and paper-and-pencil mental rotation tasks: a validation study.

The present study aimed at validating a computerized mental rotation task developed for use in functional Magnetic Resonance Imaging (fMRI) studies. Eighty-three females and 74 males completed the computerized task, two pencil-and-paper tests of mental rotation, and reported their high school grades in mathematics, English, and history. The computerized task involved the presentation of pairs of three-dimensional stimuli that differed in orientation by 0, 40, 80, 120, or 160 degrees.

Bone mineral density in the complete androgen insensitivity and 5alpha-reductase-2 deficiency syndromes.

Context: Subjects with complete androgen insensitivity (CAI) and 5alpha-reductase-2 deficiency (5alphaRD-2) are natural human models to study the direct effect of androgens on bone mineral density (BMD).

Objective: The objective of this study was to test the hypothesis that androgens have a direct effect on BMD in men.

Design: This was a prospective, observational study (1989-1999) using dual energy x-ray absorptiometry.

Sex differences in mental rotation: top-down versus bottom-up processing.

Functional MRI during performance of a validated mental rotation task was used to assess a neurobiological basis for sex differences in visuospatial processing. Between-sex group analysis demonstrated greater activity in women than in men in dorsalmedial prefrontal and other high-order heteromodal association cortices, suggesting women performed mental rotation in an effortful, "top-down" fashion. In contrast, men activated primary sensory cortices as well as regions involved in implicit learning (basal ganglia) and mental imagery (precuneus), consistent with a more automatic, "bottom-up" strategy.

Long-term growth hormone therapy in adulthood results in significant linear growth in siblings with a PROP-1 gene mutation.

PROP-1 gene mutations result in impaired production of GH, gonadotropins, TSH, and prolactin. We describe three adult siblings, aged 18-25 yr, with short stature, hypothyroidism, and lack of pubertal maturation, who were homozygous for 301-302delAG PROP-1 mutation. We had the unique opportunity to treat them in adulthood with GH for 4-5 yr and thyroid replacement before sex steroid replacement.

Mutations in CYP11B1 gene: phenotype-genotype correlations.

11beta-hydroxylase deficiency, an autosomal recessive disorder, is the second most common cause of congenital adrenal hyperplasia. We studied four subjects with classic 11beta-hydroxylase deficiency and severe hypertension: a 46,XX affected subject from a Turkish family with severe ambiguity of the external genitalia and hypertension, and three affected 46,XY subjects from a Dominican kindred with isosexual precocious puberty and severe hypertension. The affected subjects had significantly elevated plasma 11-desoxycortisol, 11-desoxycorticosterone, Delta4-androstenedione, and testosterone.

Androgen-induced prostate-specific antigen gene expression is mediated via dihydrotestosterone in LNCaP cells.

Prostate cancer is a leading cause of cancer death in American males. Androgens play an essential role in prostate development, growth and pathogenesis of benign prostate hyperplasia, and prostate cancer. Although testosterone is the main androgen secreted from the testes, dihydrotestosterone (DHT), a more potent androgen converted from testosterone by 5alpha-reductase isozymes, type 1 and 2, is the major androgen in the prostate cells.