Effects of smooth and rough Pasteurella haemolytica lipopolysaccharides on plasma cyclic-nucleotides and free fatty acids in calves

The present study examined the potency of smooth or rough Pasteurella haemolytica lipopolysaccharide infusion (LPS, 24 ng kg-1 min-1 for 500 min) on plasma cyclic-nucleotides and several free fatty acids (FFA) in calves. Both smooth or rough LPS increased plasma cAMP immediately to its maximum at 1 h of infusion, whereas plasma cGMP levels rose slowly and peaked 12 h later. The increases in cAMP levels were more prolonged for smooth LPS than rough LPS. The maximum plasma cAMP rise coincided with increases of several plasma FFA. Rough LPS increased plasma oleic greater than palmitic greater than stearic greater than linoleic acids in the second hour and reached their steady state levels between 2 h of infusion and 5 h post-infusion. Thereafter, oleic acid remained maximally elevated, while stearic acid decreased and other FFA returned to baseline. Smooth LPS had no effects on palmitic and stearic acids, but elevated oleic acid in an essentially similar manner to rough LPS and increased linoleic acid initially at 5 h, followed by decreases throughout post-infusion. These results demonstrate that endotoxemia produces early marked elevations in plasma cAMP, a gradual rise in plasma cGMP and disproportionate increases in several plasma FFA. The data also demonstrate that smooth and rough LPS differ in their abilities to increase plasma cAMP and FFA and these may be attributed to differences in their in vivo mechanisms of action. The study suggests that cAMP and cGMP may mediate actions of endotoxin at the cellular level and that differences exist in release and/or utilization of each FFA at different stages of endotoxemia.     

Association of induction of protease and chitinase in chickpea roots with resistance to Fusarium oxysporum f.sp. ciceri

To improve the breeding of chickpea varieties with resistance to Fusarium wilt, an attempt was made to analyse the biochemical basis of disease resistance by measuring levels of chitinase, β-1,3-glucanase, protease and proteinase inhibitor activities in dry and soaked seeds and in root and shoot tissues of wilt-resistant and wilt-susceptible cultivars. Marginal variation was observed in the levels of the candidate proteins in dry or soaked seeds. Chitinase activity was higher in roots than in shoots or cotyledons. No proteinase inhibitor activity was detected in root and shoot tissue of any of the cultivars. When the levels of these proteins were analysed in resistant (Vijay) and susceptible (JG-62) cultivars during development of wilt by growing plants in soil infested with F. oxysporum f.sp. ciceri , race 1, both cultivars showed induction of chitinase activity in the roots. However, the induced activity in JG-62 (3.82 U g⁻¹) was equivalent to the constitutive level in Vijay (3.90 U g⁻¹) and much lower than that induced in Vijay (5.18 U g⁻¹). Induction of protease activity was observed only in root extracts of Vijay when challenged by the pathogen. The root extract of Vijay showed in vitro antifungal activity in a plate assay. Simultaneous induction of proteolytic and chitinolytic activities specifically in the resistant cultivar was correlated with antifungal properties of root extracts effective in conferring resistance.     

Rearing performance of Clarias batrachus larvae: Effect of age at stocking on growth and survival during fingerling production

An experiment was conducted to evaluate the rearing performance of different larval stages for optimum growth and survival during fingerling production of Clarias batrachus with an aim to reduce the rearing time of the catfish larvae in a hatchery system. The larvae were reared for 5, 10 and 15 days before stocking them in the nursery tanks. No significant (P < 0.05) difference could be found in length increment at the end of first week of rearing. But the total length was reduced during rest three weeks in five days old larvae compared to that of other two higher age groups. In 5 days old larvae the reduced weight (P < 0.05) was observed during the entire rearing period. However, the specific growth rate (SGR) did not vary among the groups. The survival rate as well as total biomass was decreased while stocking five days old larvae for rearing, compared to that of other two age groups.     

Arachidonic acid immunoregulation in lambs persistently infected with border disease virus

To evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene C4 (LTC4), prostaglandin D2 (PGD2) and their plasma fatty acid (FA) precursor, arachidonic acid (AA), in six lambs with congenital border disease (BD). Significantly elevated average plasma LTC4 during the first half year of life was associated with increased PDG2 when compared to uninfected control lambs. Significantly elevated total plasma esterified AA stores suggest an effective BDV-mediated prostenoid immunostimulation. However, at 1 yr old, prostenoid secretion had fallen to normal (LTC4) or below normal (PGD2) levels. In contrast, there remained significantly elevated plasma esterified AA, present as available substrate for formation of these anti-viral immunoregulatory agents. These results suggested that preventing mobilization of AA from lipid stores for effective immune responses may be a viral strategy of BD virus that is associated with long term border disease effects.     

Biochemical and haematological changes following prolonged halothane anaesthesia in horses

Six healthy horses were anaesthetised with halothane (1·2 times the horse minimal alveolar concentration) in oxygen for more than 12 hours. Serum bilirubin, aspartate aminotransferase, alkaline phosphatase and L-iditol dehydrogenase values were significantly (P<0·05) increased for up to nine days after anaesthesia. These changes suggest au anaesthesia related liver dysfunction. Creatine kinase increased to an average of more than 1400 iu litre⁻¹ 24 hours after anaesthesia and this change is indicative of muscle cell disruption. Renal-associated biochemical results, (that is serum creatinine and inorganic phosphate concentrations) were significantly increased transiently and are indicative of reduced renal function during and immediately after anaesthesia. Plasma concentrations of eicosanoids (6-keto-PGF_1a, PGF_2a, pge and thromboxane) following anaesthesia were not different from preanaesthetic values. The magnitude of liver and muscle cell related increases in serum enzyme activities resulting from prolonged halothane anaesthesia was in excess of that previously reported for anaesthesia of shorter duration.     

Role of eicosanoids, histamine, and serotonin in the pathogenesis of Klebsiella pneumoniae-induced bovine mastitis

By inoculating Klebsiella pneumoniae into the teat canals of mammary glands, coliform mastitis was induced experimentally in 6 lactating cows. Release of eicosanoids, histamine, and serotonin in plasma and milk was studied in response to 2 doses of K pneumoniae. A low dose (mean, 5,000 organisms/ml) was inoculated into cows 1 through 4, and a high dose (mean, 200,000 organisms/ml) was inoculated into cows 5 and 6. Milk and blood samples were collected before inoculation (0 hours), and hourly, from 3 to 24 hours after inoculation. Concentrations of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E (PGE), thromboxane B2 (TxB2), histamine, and serotonin were measured in plasma and milk obtained from control (NaCl solution-inoculated) and infected quarters. Fluorometric analysis of milk from infected quarters revealed significantly increased histamine and serotonin concentrations regardless of the dose of K pneumoniae. The mean (+/- SEM) peak concentrations of histamine were significantly (P less than 0.01) increased from the preinoculation value of 44 (+/- 12) ng/ml to 312 (+/- 104) ng/ml in milk from infected quarters and 72 (+/- 24) ng/ml in milk from control quarters. The mean peak concentration of serotonin increased significantly from the preinoculation concentration of 436 (+/- 37) ng/ml to 1,754 (+/- 662) ng/ml and 4,867 (+/- 1,248) ng/ml in milk from control (P less than 0.02) and infected (P less than 0.001) quarters, respectively. However, serotonin concentration in milk from infected quarters was approximately 2.8 times greater than that in milk from control quarters. Concentrations of PGF2 alpha, PGE, and TxB2 in milk and plasma were evaluated by radioimmunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cyclic nucleotides in hamster retina

The concentrations of cyclic 3':5'-adenosine monophosphate (cyclic AMP) and cyclic 3':5'-guanosine monophosphate (cyclic GMP) were determined in white light- and dim red light-adapted golden Syrian hamster retinas. Retinas from animals in dim red light had cyclic AMP concentrations of 9.29 +/- 2.94 pmol/mg of protein and cyclic GMP concentrations of 110.62 +/- 32.98 pmol/mg of protein. After white light adaptation, retinal cyclic AMP and cyclic GMP concentrations were reduced to 74% and 45% of the previous values, respectively. In another experiment with white light-adapted animals, the sex or method of immobilization of the animals (cervical dislocation vs sodium pentobarbital) had no significant effect on cyclic nucleotide values.