Oestradiol Induced Inhibition of Neuroendocrine Marker Expression in Leydig Cells of Adult Rats

The objectives of this work were to determine the changes in the expression of neuroendocrine markers in Leydig cell by oestradiol treatment, and to determine whether testosterone is able to recover partially the effects of hormonal suppression induced by oestradiol. Adult male rats were injected daily with either 50 microg of oestradiol or oestradiol plus testosterone propionate (25 mg every 3 days) for 15 days. The animals were sacrificed and testicles were dissected and processed by routine histological protocols. FSH and LH serum levels were determined by radioimmunoassay. The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A (CrA), S-100 protein (S-100), P substance (PS), synaptofisin (SYN), neurofilament protein (NF), gliofibrillary acidic protein (GFAP) and neuron specific enolase (NSE) were used. The mean LH and FSH serum concentrations were consistently suppressed with hormonal treatments. Intermediate filaments (NF and GFAP) showed no difference in their expression. The expression of S-100, NSE and SYN was significantly lower in both hormone-treated groups. In oestradiol-treated rats, the immunoreactivity of CrA and SP decreased significantly but was restored after testosterone supplementation. Although the nature and functions of many of these substances in Leydig cells remain unknown, these results are consistent with the hypothesis that the expression of some neuroendocrine markers is hormonally controlled.     

Relationship of blood corticosterone, immunoglobulin and haematological values in young crocodiles (Crocodylus porosus) to water temperature, clutch of origin and body weight

Objective To examine whether sub-optimal temperature induced stress and immunosuppression in farmed saltwater crocodile (Crocodylus porosus) hatchlings. Design A clinico-pathological study. Animals A total of 140 hatchlings were used. Procedure Body weight and length, plasma corticosterone and immunoglobulin concentrations and total and differential white blood cell counts were measured in 140 hatchlings from five clutches divided between five water temperature treatment groups. Initially all groups were housed at 32°C for 10 weeks, then two groups (L, LC) were changed to low temperature (28°C) and two groups (H, HC) to high temperature (36°C), while one group (C) remained at 32°C. The LC and HC groups were maintained at these temperatures for 10 days, after which the water temperature of both groups was returned to 32°C. Blood samples were collected twice (at 6 and 9 weeks of age) before the initial temperature change, and at 10 days and 4 weeks after the initial temperature change (at 11.5 and 14 weeks of age). Results Except for an increase in plasma corticosterone in the HC group and a decrease in the L group when the temperature change was first introduced, changes in plasma corticosterone were not significant. There were no significant changes in immunoglobulin concentrations. There were, however, significant decreases in the total white cell and lymphocyte counts in the LC group after the temperature was decreased to 28°C, and an increase in these counts after water temperature was returned to 32°C. Clutch of origin had significant effects on body weight and length gains, and there were negative relationships between body weight and corticosterone concentrations and between body weight and immunoglobulin concentrations. Conclusions As haematological changes indicative of stress were not associated with significant changes in serum corticosterone, immunosuppression in young crocodiles may be independent of the hypothalamic-pituitary-adrenal cortical axis.     

On the distribution of tree growth stresses

Summary A plane strain pure bending elastic model is used to predict stress states in a cylindrically orthotropic cylinder due to asymmetric strain distributions continously induced at the periphery. A general solution for the stress states related to each component of the strain distribution expanded in a Fourier series is given. Details of solutions for eleven representative tree species are given. Also the change of curvature of a stem caused by a measured peripheral strain distribution is computed for a given period of growth.     

Residual stresses caused by growth stresses within a stem with radially varying spiral grain angle – two numerical solution approaches: 1) finite element method and 2) transfer matrix method

Two numerical methods, the Finite Element (FE) method and the Transfer Matrix (TM) method, have been applied to derive a solution for residual stresses in a stem. The source of stress is the maturation strains in new wood cells, which give rise to growth stresses. The methods are generally applicable to the case of spiral grain with a grain angle varying with radius, which often is the case in trees. Also, the methods allow for the elastic constants to vary with the radius, which is important to model, for example, juvenile wood. The numerical solutions are checked against an analytical solution in the case of a constant grain angle, and are found to coincide. In addition, the two methods are shown to independently produce the same stress distribution for one pattern of grain angle variation. This shows that the methods are reliable, and they will be used for obtaining a wider range of solutions in a subsequent paper. Received: 13 January 1998     

An extension of Jacobs' method for measuring residual growth strains in logs

Summary Previous methods for measuring residual longitudinal growth strain distributions in logs are reviewed. An extension is given of Jacobs' method for measuring growth strains which yields residual strain information at many points in the cross section other than along the diametrical plank. Some of the longitudinal growth strain distributions measured using the new method are presented.This work was supported in part by NSF Grant ENG-74-02428     

Oral Cyclosporine Treatment in Dogs: A Review of the Literature

Cyclosporine is an immunomodulatory drug used to treat an increasing spectrum of diseases in dogs. Cyclosporine is a calcineurin inhibitor, ultimately exerting its inhibitory effects on T‐lymphocytes by decreasing production of cytokines, such as interleukin‐2. Although, in the United States, oral cyclosporine is approved in dogs only for treatment of atopic dermatitis, there are many other indications for its use. Cyclosporine is available in 2 oral formulations: the original oil‐based formulation and the more commonly used ultramicronized emulsion that facilitates oral absorption. Ultramicronized cyclosporine is available as an approved animal product, and human proprietary and generic preparations are also available. Bioavailability of the different formulations in dogs is likely to vary among the preparations. Cyclosporine is associated with a large number of drug interactions that can also influence blood cyclosporine concentrations. Therapeutic drug monitoring (TDM) can be used to assist in attaining consistent plasma cyclosporine concentrations despite the effects of varying bioavailability and drug interactions. TDM can facilitate therapeutic success by guiding dose adjustments on an individualized basis, and is recommended in cases that do not respond to initial oral dosing, or during treatment of severe, life‐threatening diseases for which a trial‐and‐error approach to dose adjustment is too risky. Pharmacodynamic assays that evaluate individual patient immune responses to cyclosporine can be used to augment information provided by TDM.     

Cross-protective immunity and the serological classification system for Bacteroides nodosus

The relationship between the serological classification system for serogroup B and for serogroup H of Bacteroides nodosus and cross-protection between subgroups within these serogroups was examined. Protection against ovine footrot following vaccination was achieved against other subgroup strains provided sufficient cross-reactive antibody was induced by shared pilus antigens. Within serogroup B, better cross-protection against one subgroup was obtained with a pili vaccine than a whole cell vaccine which correlated with higher pilus antibody titres induced by the former. For serogroup H, a lack of cross-protection and serological reactivity between subgroups was demonstrated, which indicates that the prototype strain of subgroup H2 should be designated a new serogroup.