Supplemental methionine and time of supplementation effects on ruminal fermentation, digesta kinetics, and in situ dry matter and neutral detergent fiber disappearance in cattle

Two experiments were conducted to study the effects of methionine supplementation on ruminal fermentation and digesta kinetics. In Exp. 1, nine ruminally cannulated beef heifers (average initial BW = 527 kg) in a crossover design were fed low-quality grass hay and cottonseed meal with or without 11.4 g of supplemental methionine (polysaccharide-coated). Particulate and fluid kinetics, rate of DM and NDF disappearance, ruminal VFA and NH3 N concentrations, and pH were not altered (P > .10) by supplemental methionine; however, ruminal purine concentration was greater (P < .05) in methionine-supplemented heifers than in unsupplemented heifers. In Exp. 2, 12 ruminally cannulated Holstein steers (average initial BW = 622 kg) grazing a fescue pasture were allotted to one of three groups: no supplemental methionine (CON) or 11.4 g of supplemental methionine fed at 0700 (AM) or at 1200 (PM). Forage intake, particulate kinetics, ruminal fluid kinetics, pH, VFA, and NH3 N concentrations were not altered (P > .10) by supplemental methionine or supplementation time. In situ rate of DM and NDF disappearance was greater (P < .05) in supplemented steers than in CON steers; AM steers exhibited faster (P < .05) rates than PM steers. Overall, methionine supplementation of low-quality forage increased ruminal purine concentration but did not alter in situ fermentation or digesta passage, whereas supplementation at 0700, but not at 1200, of steers grazing fescue forage increased rate of NDF fermentation.     

Localization of glutamate receptors in dorsal horn of rat spinal cord

Immunocytochemical localization of metabotropic glutamate receptors (mGluRs) and ionotropic glutamate receptors (NMDA-type: NMDAR1 and NMDAR2A-C; AMPA-type: GluR1-4) was performed on sections of rat dorsal horn. Immunoreactivity for mGluR1 alpha was detected in laminae I-III of the dorsal horn, whilst mGluR2/3 immunoreactivity was detected primarily in lamina III. Immunoreactivity for NMDAR1, GluR1, GluR2, GluR2/3, GluR4 and GluR5/6/7 was strongly localized in neuronal elements of laminae I-III. Immunoreactivity for NMDAR2B was localized in laminae I-III. No mGluR5, NMDAR2A and NMDAR2C immunoreactivity was detected. In addition, immunoreactivity for receptors was found to co-localize with immunoreactivity for glutamate in the dorsal horn. The present results indicate that glutamate receptors are differentially localized in neuronal elements of dorsal horn where receptor-neurotransmitter interaction takes place.     

Postnatal survival and growth of mouse irradiated in utero with low dose

In order to investigate radiation risks associated with low dose and low dose-rates, pregnant Swiss albino mice were exposed to gamma rays, 0.80 Gy from a cobalt-60 source at two different dose-rates (0.0795 and 0.0012 Gy/min) on 18 day post conception. In females exposed to lower dose-rate (0.0012 Gy/min), litter size was found to be decreased, while those exposed to higher dose-rate (0.0795 Gy/min), it remained unaltered. In both groups, appearance of fur and development of complete fur were delayed, whereas gait was delayed only in higher dose-rate group. Male offspring exhibited a biphasic mode of weight loss, while female offspring after an initial weight loss at 1 week, displayed a continuous recovery, but could not attain the normal weight till 12 weeks of age. It appears that higher dose-rate is more effective in delaying the appearance of physiological markers and weight loss, while in terms of litter size lower dose-rate (0.0012 Gy/min) is more effective.     

An epidemiological profile of elderly suicides in Hong Kong

Suicide rates in Hong Kong increased with age, and the highest suicide rate occurred among the oldest age groups. Hong Kong has one of the highest elderly suicide rates in the world. The elderly suicide rate was four to five times above the average. Furthermore, gender differences were observed among different marital status groups. For example, single males had a much higher rate than single females and married males had a higher rate than their widowed counterparts. The suicide rate for an economically inactive person was six times higher than for an active one. Jumping has become increasingly common and seems to substitute for other methods of suicide. Winter months and the Chinese New Year period had the lowest suicide occurrence. Some explanations are given.     

Ca2+-dependent structural changes in C-type mannose-binding proteins

C-type animal lectins are a diverse family of proteins which mediate cell-surface carbohydrate-recognition events through a conserved carbohydrate-recognition domain (CRD). Most members of this family possess a carbohydrate-binding activity that depends strictly on the binding of Ca2+ at two sites, designated 1 and 2, in the CRD. The structural transitions associated with Ca2+ binding in C-type lectins have been investigated by determining high-resolution crystal structures of rat serum mannose-binding protein (MBP) bound to one Ho3+ in place of Ca2+, and the apo form of rat liver MBP. The removal of Ca2+ does not affect the core structure of the CRD, but dramatic conformational changes occur in the loops. The most significant structural change in the absence of Ca2+ is the isomerization of a cis-peptide bond preceding a conserved proline residue in Ca2+ site 2. This bond adopts the cis conformation in all Ca2+-bound structures, whereas both cis and trans conformations are observed in the absence of Ca2+. The pattern of structural changes in the three loops that interact with Ca2+ is dictated in large part by the conformation of the prolyl peptide bond. The highly conserved nature of Ca2+ site 2 suggests that the transitions observed in MBPs are general features of Ca2+ binding in C-type lectins.     

Effectiveness of chlorine dioxide in disinfection on two soft denture liners

OBJECTIVE: The purpose of this study was to evaluate a hydroxylapatite-based material and calcium sulfate when each was used under a resin-modified glass ionomer cement to repair furcation perforations. STUDY DESIGN: Perforations of pulp chamber floors were made in 72 teeth of 9 dogs. Perforations were divided into 3 equal-sized groups and repaired with resin-modified glass ionomer either alone or over an artificial floor. The artificial floor was either a hydroxylapatite-based material or calcium sulfate. Three dogs were killed at each of 3 intervals (1, 3, and 6 months). The tissue response to the tested materials was evaluated clinically, radiographically, and histologically. RESULTS: The hydroxylapatite-based material showed the highest radiographic success; this was followed by calcium sulfate and glass ionomer. From histologic evaluation, the average success rate was found to be 67% for calcium sulfate, 62% for the hydroxylapatite-based material, and 59% for glass ionomer. However, there was no statistical significant difference with the resin-modified glass ionomer when it was used alone and when it was used over a barrier. There was also no significant difference between the hydroxylapatite-based material and the calcium sulfate when they were used as artificial floors. CONCLUSION: The use of an artificial floor may not be necessary when flowable resin-modified glass ionomer cements are used.     

Sites of alcohol and volatile anaesthetic action on GABA(A) and glycine receptors

Volatile anaesthetics have historically been considered to act in a nonspecific manner on the central nervous system. More recent studies, however, have revealed that the receptors for inhibitory neurotransmitters such as gamma-aminobutyric acid (GABA) and glycine are sensitive to clinically relevant concentrations of inhaled anaesthetics. The function of GABA(A) and glycine receptors is enhanced by a number of anaesthetics and alcohols, whereas activity of the related GABA rho1 receptor is reduced. We have used this difference in pharmacology to investigate the molecular basis for modulation of these receptors by anaesthetics and alcohols. By using chimaeric receptor constructs, we have identified a region of 45 amino-acid residues that is both necessary and sufficient for the enhancement of receptor function. Within this region, two specific amino-acid residues in transmembrane domains 2 and 3 are critical for allosteric modulation of both GABA(A) and glycine receptors by alcohols and two volatile anaesthetics. These observations support the idea that anaesthetics exert a specific effect on these ion-channel proteins, and allow for the future testing of specific hypotheses of the action of anaesthetics.     

N-cadherin-catenin interaction: necessary component of cardiac cell compartmentalization during early vertebrate heart development

During early heart development the expression pattern of N-cadherin, a calcium-dependent cell adhesion molecule, suggests its involvement in morphoregulation and the stabilization of cardiomyocyte differentiation. N-cadherin's adhesive activity is dependent upon its interaction with the intracellular catenins. An association with alpha-catenin and beta-catenin also is believed to be involved in cell signaling. This study details the expression patterns of alpha-catenin, beta-catenin, and gamma-catenin, during definition of the cardiac cell population as distinct compartments in the anterior regions of the chick embryo between stages 5 and 9. The restriction of N-cadherin/catenin localization at stage 5+ from a uniform pattern in vivo, to specific cell clusters that demarcate areas where mesoderm separation is initiated, suggests that the N-cadherin/catenin complex is involved in boundary formation and in the subsequent cell sorting. The latter two processes lead to the specification and formation of the somatic and cardiac splanchnic mesoderm. N-cadherin colocalized with alpha- and beta-catenin at the cell membrane before and during the time that its expression becomes restricted to the lateral mesoderm and continues cephalocaudad into stage 8. These proteins continue to colocalize in the myocardium of the tubular heart. Plakoglobin is not expressed in this region during stages 6-8, but is detected in the myocardium later at stage 13. The observed in vivo expression patterns of alpha-catenin, beta-catenin, and plakoglobin suggest that these proteins are directly linked with the developmental regulation of cell junctions, as cardiac cells become stably committed and phenotypically differentiated to eventually form a mature myocardium. The localization of N-CAM also was analyzed during these stages to determine whether the N-cadherin-catenin localization was unique or whether other cell adhesion molecules were expressed similarly. The results indicate that the unique pattern of N-cadherin expression is not shared with N-CAM. We also show that perturbation of N-cadherin using a function perturbing N-cadherin antibody (NCD-2) inhibits normal early heart development and myogenesis in a cephalocaudad, stage-dependent manner. We propose a model whereby myocardial cell compartmentalization also defines the endocardial population. The presence of beta-catenin suggests that a similar signaling pathway involving Wnt (wingless)-mediated events may function in myocardial cell compartmentalization during early vertebrate heart development, as in Drosophila contractile vessel development.