Effects of low dosages of intravenous dexamethasone on serum cortisol concentrations in the normal cat

The suppressive effects of three different low dosages of dexamethasone (5, 10 and 15 micrograms kg-1) on serum cortisol concentrations were evaluated in 10 normal cats. On four different days, serum was collected before and at two, four, six and eight hours after the intravenous administration of saline or dexamethasone. Following the administration of saline, no significant difference in mean serum cortisol concentrations was noted between the basal or postinjection values. In contrast, mean serum cortisol concentrations decreased significantly (P less than 0.05) by two hours and remained significantly below mean basal values eight hours after injection of all three dosages of dexamethasone. The degree of cortisol suppression became progressively greater as the dosages of dexamethasone were increased. After administration of the highest dose of dexamethasone (15 micrograms kg-1), serum cortisol decreased to below 5 ng ml-1 by two to four hours and remained suppressed (under 5 ng ml-1) eight hours after injection in all cats. In contrast, two of the 10 cats showed a slight escape from cortisol suppression by eight hours after injection of dexamethasone at the dosage of 10 micrograms kg-1, whereas a dosage of 5 micrograms kg-1 failed to suppress cortisol concentrations below 10 ng ml-1 at any of the sampling times in one cat and was associated with increasing serum cortisol concentrations at eight hours after injection in three cats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Basal and ACTH-Stimulated Plasma Aldosterone Concentrations are Normal or Increased in Dogs With Trichuriasis-Associated Pseudohypoadrenocorticism

We measured plasma concentrations of Cortisol and aldosterone before and after administration of adrenocorticotropin (ACTH) in dogs with trichuriasis. These dogs had physical examination, historical, and serum electrolyte findings suggestive of hypoadrenocorticism; trichuriasisassociated pseudohypoadrenocorticism has been reported previously. We found normal basal and ACTH-stimulated plasma Cortisol concentrations. Basal and ACTH-stimulated plasma aldosterone concentrations were normal in 2 dogs and increased in 3 dogs, suggesting that the electrolyte abnormalities seen in this clinical syndrome are not due to aldosterone deficiency.     

Influenza viruses in birds of the Atlantic flyway.

Isolation of type A influenza viruses from the feces of 5013 birds of 16 species was attempted during a 33-month study (1977-79). Seventy viruses were isolated from the feces of 3403 ring-billed gulls in Baltimore, Md., during 16 months of sampling. Six hemagglutinin (HA) subtypes and seven neuraminidase (NA) subtypes in 15 combinations were found. The H13N6 virus was the only subtype found each year and accounted for 40% of the isolates. The rate of isolation from gulls was 0.26% in the cold months and 3.0% in the warm months. Hemagglutination-inhibition (HI) and elution-inhibition antibody profiles reflected the presence of some but not all of the viruses isolated. In mute swans, the rates of seroconversions were 16% for HA antibody and 14% for NA antibody, whereas the viral isolation rate was 0.4% over a 3-year period. Both the H5 and the N2 subtypes, which were responsible for the lethal chicken outbreaks in 1983 in Pennsylvania, were isolated from gulls in 1978 in association with subtypes not found in the chicken virus. Also, seroconversions for the H5 HA occurred in mute swans in 1978.     

Black walnut extract-induced laminitis in horses is associated with heterogeneous dysfunction of the laminar microvasculature

REASONS FOR PERFORMING STUDY: Equine laminitis purportedly involves haemodynamic dysfunction at the level of the laminar vasculature. However, to date, no studies have been performed characterising the function of laminar arteries and veins during the prodromal stages of equine laminitis. HYPOTHESIS: That the prodromal stages of laminitis are associated with contractile dysfunction of the equine laminar vasculature. OBJECTIVE: To assess contractile function of laminar arteries and veins to phenylephrine (PE) and 5-hydroxytryptamine (5-HT). METHODS: Horses were administered black walnut heartwood extract (BWHE) or water (control horses) via nasogastric intubation. After euthanasia, laminar vessels (100-800 microm internal diameter) were isolated and mounted on small vessel myographs to assess contractile function. RESULTS: Contractile responses to PE or 5-HT were identical in laminar arteries isolated from either control horses or those administered BWHE. In contrast, responses to PE or 5-HT were significantly reduced in laminar veins isolated from BWHE-administered horses when compared with laminar veins isolated from control horses. CONCLUSIONS AND POTENTIAL RELEVANCE: These results are consistent with the prodromal stages of laminitis being associated with selective dysfunction of laminar veins. Further studies are required to discern the precise nature of this dysfunction and its potential relevance to the pathogenesis of acute laminitis in the horse and possible therapeutic targets for treatment.     

Use of a multifenestrated indwelling lavage system for treatment of septic digital teno-synovitis in cattle

Septic tenosynovitis was diagnosed in seven cattle on the basis of history, physical examination, radiographs, cytological examination of tendon sheath fluids, and microbial culture. A commercially available indwelling multifenestrated silicone rubber drain was used to perform frequent lavage of the flexor tendon sheaths. The sepsis resolved in all cattle. Five of six cattle for which long-term (> 1 year) follow-up information was available were clinically sound on the affected limb and had remained productive members of the herd.     

Isolation and characterization of polyphenol type-A polymers from cinnamon with insulin-like biological activity

The causes and control of type 2 diabetes mellitus are not clear, but there is strong evidence that dietary factors are involved in its regulation and prevention. We have shown that extracts from cinnamon enhance the activity of insulin. The objective of this study was to isolate and characterize insulin-enhancing complexes from cinnamon that may be involved in the alleviation or possible prevention and control of glucose intolerance and diabetes. Water-soluble polyphenol polymers from cinnamon that increase insulin-dependent in vitro glucose metabolism roughly 20-fold and display antioxidant activity were isolated and characterized by nuclear magnetic resonance and mass spectroscopy. The polymers were composed of monomeric units with a molecular mass of 288. Two trimers with a molecular mass of 864 and a tetramer with a mass of 1152 were isolated. Their protonated molecular masses indicated that they are A type doubly linked procyanidin oligomers of the catechins and/or epicatechins. These polyphenolic polymers found in cinnamon may function as antioxidants, potentiate insulin action, and may be beneficial in the control of glucose intolerance and diabetes.