Osteopontin immunoreactivity in the ileum and ileocecal lymph node of dairy cows naturally infected with Mycobacterium avium subsp. paratuberculosis

Osteopontin (Opn), a highly acidic glycoprotein, promotes cellular adhesion and recruitment and has been shown to be upregulated in the granulomas of mycobacterial infections. Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is associated with granulomatous enteritis. The objective of this experiment was to identify Opn in the ileum and ileocecal lymph node (ICN) of dairy cows naturally infected with MAP and to compare the frequency and intensity of staining between noninfected healthy controls, subclinical and clinical cows. Sections from these three groups of animals were selected from a tissue archive. Immunohistochemical analysis was used to determine the location and expression of Opn. The frequency and intensity of staining was also reported. Confirmation of acid-fast bacilli in the tissue sections was achieved by the Ziehl-Neelsen method. Within the ileal tissue, macrophages, lymphocytes, and plasma cells stained positive for Opn. Clinical cows expressed Opn at a greater frequency in the lamina propria. Control and subclinical cows did not have areas of granulomatous inflammation but cells staining for Opn were equally intense for the three groups. The frequency of staining for Opn in the ICN was not affected by MAP infection. Results of this study confirm for the first time, the expression of Opn in the ileum and ICN of MAP-infected cattle.     

Developmental changes in cholesterol 7alpha- and 27-hydroxylases in the piglet

Hepatic cholesterol 7alpha-hydroxylase (CYP7A) and sterol 27 hydroxylase activities were measured in fetal, newborn, suckling, and weaned piglets from 76 d into gestation to 49 d of age. Hepatic CYP7A activity was not detected in fetal microsomes, but it increased to 6.8 +/- 2.6 pmol/min x mg(-1) protein in suckling piglets at 21 d of age and to 18.2 +/- 2.5 in weaned piglets at 49 d of age. Hepatic CYP7A activity was not different between 49-d-old piglets weaned at 21 d and piglets suckled for 49 d (18.9 +/- 2.6 and 18.2 +/- 2.5 pmol/min x mg protein, respectively). Fasting for 14 h decreased CYP7A activity by 86% in both suckled and weaned piglets. Cholesterol 7alpha-hydroxylase activity remained decreased for at least 5 h after refeeding. Sterol 27-hydroxylase activity was also undetectable near birth, but was detectable by 21 d of age. Postnatally, sterol 27-hydroxylase activity was not influenced by age or suckling and weaning, as was CYP7A. Sterol 27-hydroxylase was decreased by 80% in piglets deprived of feed compared with piglets given free access. In contrast to CYP7A activity, 27-hydroxylase activity returned within 5 h after refeeding to levels observed in piglets given ad libitum access to feed. Similar to CYP7A enzyme activity, hepatic CYP7A mRNA was not detected in newborn piglets, but increased from 2.7 +/- 1.7 pg mRNA/microg RNA in suckling piglets at 21 d to 13.7 +/- 1.2 in 49-d-old piglets weaned at 21 d. As with enzyme activity, feed deprivation decreased CYP7A mRNA to barely detectable levels (< .5 pg/microg RNA), and which remained decreased for at least 5 h following refeeding (.6 +/- .3 and 2.67 +/- .4 pg mRNA/microg RNA for suckled and weaned piglets, respectively). In piglets allowed free access to feed, CYP7A mRNA concentrations were associated positively (P = .001) with enzyme activity. These results suggest that developmental regulation of CYP7A activity is the result of a pretranslational mechanism.     

Bee venom pretreatment has both an antinociceptive and anti-inflammatory effect on carrageenan-induced inflammation

Although the injection of bee venom (BV) has been reported to evoke tonic pain and hyperalgesia, there is conflicting evidence in the literature indicating that BV can also exert an anti-inflammatory and antinociceptive effects on inflammation. In this regard, BV has been traditionally used in Oriental medicine to relieve pain and to treat chronic inflammatory diseases such as rheumatoid arthritis. The present study was designed to test the hypothesis that BV induces acute nociception under normal conditions, but that it can serve as a potent anti-inflammatory and antinociceptive agent in a localized inflammatory state. The experiments were designed to evaluate the effect of BV pretreatment on carrageenan (CR)-induced acute paw edema and thermal hyperalgesia. In addition, spinal cord Fos expression induced by peripheral inflammation was quantitatively analyzed. In normal animals subcutaneous BV injection into the hindlimb was found to slightly increase Fos expression in the spinal cord without producing detectable nociceptive behaviors or hyperalgesia. In contrast pretreatment with BV (0.8 mg/kg) 30 min prior to CR injection suppressed both the paw edema and thermal hyperalgesia evoked by CR. In addition, there was a positive correlation between the percent change in paw volume and the expression of Fos positive neurons in the spinal cord. These results indicate that BV pretreatment has both antinociceptive and anti-inflammatory effects in CR-induced inflammatory pain. These data also suggest that BV administration may be useful in the treatment of the pain and edema associated with chronic inflammatory diseases.     

Adipose tissue growth and cellularity: changes in bovine adipocyte size and number

Forty crossbred steers of similar birth date and fed the same growing-finishing diet were used to study adipocyte changes in six fat depots during growth from 11 to 19 mo of age. Steers were slaughtered at 2-mo intervals. Adipose tissue samples were obtained from kidney, mesenteric and brisket fat and subcutaneous, intermuscular and intramuscular fat from the 10th to 12th rib section. The osmium tetroxide fixation technique was used for determination of cell size and number. Except for three brisket fat samples, distributions of adipocyte diameters from six different fat depots were monophasic during the age range considered in this study. At 17 mo of age, the mean adipocyte diameter, in decreasing order, was: kidney fat greater than mesenteric greater than subcutaneous greater than intermuscular greater than intramuscular greater than brisket fat. Fat deposition during growth to 19 mo of age occurred mainly by hypertrophy of adipocytes. An apparent cell hyperplasia occurred in the intramuscular fat depot from 11 to 15 mo and in the brisket fat depot after 15 mo of age. Based on cellularity characteristics, evidence exists to classify intramuscular and brisket fat depots as late-developing ones. Cell number/gram of intramuscular adipose tissue was a better predictor of marbling score than was fat cell diameter.     

Two mutant alleles of the insulin receptor gene in a patient with extreme insulin resistance

Insulin receptor complementary DNA has been cloned from an insulin-resistant patient with leprechaunism whose receptors exhibited multiple abnormalities in insulin binding. The patient is a compound heterozygote, having inherited two different mutant alleles of the insulin receptor gene. One allele contains a missense mutation encoding the substitution of glutamic acid for lysine at position 460 in the alpha subunit of the receptor. The second allele has a nonsense mutation causing premature chain termination after amino acid 671 in the alpha subunit, thereby deleting both the transmembrane and tyrosine kinase domains of the receptor. Interestingly, the father is heterozygous for this nonsense mutation and exhibits a moderate degree of insulin resistance. This raises the possibility that mutations in the insulin receptor gene may account for the insulin resistance in some patients with non-insulin-dependent diabetes mellitus.     

Prolonged, moderate nutrient restriction in beef cattle results in persistently elevated circulating ghrelin concentrations

Four ruminally cannulated steers (BW 581 +/- 12.8 kg) were used in a crossover design to determine the effects of prolonged, moderate nutrient restriction on plasma ghrelin concentrations and to establish the relationship of plasma ghrelin concentrations with hormones and metabolites indicative of nutritional status and end products of rumen fermentation. A high-grain diet was offered at 240% of the intake needed for BW maintenance (2.4xM) or 80% of the intake needed for BW maintenance (0.8xM). To standardize, all steers were acclimated to 2.4xM before initiation of the treatment periods. During period 1, 2 steers continued at 2.4xM, whereas intake for the remaining 2 steers was restricted to 0.8xM. On d 7, 14, and 21 after initiation of the restriction, serial blood samples were collected at 15-min intervals via indwelling jugular catheter and were assayed for ghrelin, GH, NEFA, insulin, and glucose concentrations. Rumen fluid was collected at hourly intervals for evaluation of pH and VFA concentrations. After period 1, steers were weighed, the treatments were switched between steer groups, and the intake amounts were recalculated. Intake of 2.4xM was established for previously restricted cattle, and period 2 was then conducted as described for period 1. Data were analyzed statistically as repeated measures in time, and stepwise regression was used to define the relationship of plasma ghrelin with hormones, metabolites, and end products of rumen fermentation. Throughout the 21-d treatment period, plasma ghrelin concentrations were elevated (P 相似文献   

Electrical conductivity of olivine, wadsleyite, and ringwoodite under upper-mantle conditions

Geophysical models show that electrical conductivity in Earth's mantle rises about two orders of magnitude through the transition zone in the depth range 410 to 660 kilometers. Impedance measurements obtained on Mg1.8Fe0.2SiO4 olivine, wadsleyite, and ringwoodite at up to 20 gigapascals and 1400 degreesC show that the electrical conductivities of wadsleyite and ringwoodite are similar and are almost two orders of magnitude higher than that of olivine. A conductivity-depth profile to 660 kilometers, based on these laboratory data, shows a conductivity increase of almost two orders of magnitude across the 410-kilometer discontinuity; such a profile favors a two-layer model for the upper mantle. Activation enthalpies of 1.2 to 1.7 electron volts permit appreciable lateral variations of conductivity with lateral temperature variations.