Suppression of prolactin in pigs by Escherichia coli endotoxin.

An endotoxin produced by Escherichia coli caused a decrease in prolactin concentrations in the plasma of sows when given at low dosages 2 days postpartum. Five to tenfold increases occurred in the plasma cortisol concentrations. Piglet growth, used as an indicator of milk secretion by the sows, was significantly depressed after the endotoxin administration. Some cases of lactation failure in the periparturient sow may thus be due to endotoxins suppressing prolactin concentrations. This appears to be the first report of a bacterial endotoxin having an effect on prolactin in any species.

Sustainable agriculture: how to sustain a production system in a changing environment.

During the past 10-15 years, sustainable agriculture has progressed from a focus primarily on a low-input, organic farming approach with a major emphasis on small fruit or vegetable production farms, often described as Low Input Sustainable Agriculture, to the current situation where sustainability is an important part of mainstream animal and plant production units. The US Department of Agriculture programmes cover a broad range of activities, including conserving the natural resource base, enhancing environmental quality, and sustaining productivity of the nation's farms. The use of Geographic Information Systems technology to direct application of fertilisers, pesticides, and herbicides is one example of a rapidly emerging technology that can reduce use of external inputs, protect the agricultural environment, and improve economic returns. This Geographic Information Systems technology also is being used to localise animal pest and disease problems, assist in regulatory or control measures, and identify high risk areas that might need different management systems or should be avoided as sites for animal production. Use of intensive grazing systems also has increased markedly over the past 5-6 years. These systems will allow longer grazing seasons in southern parts of the USA, provide more efficient use of the forages being produced and reduce labour costs in the typical dairy operation. Major animal and plant production agriculture-oriented programmes at the US Department of Agriculture focus on integrated production systems, use of Integrated Pest Management techniques, and development of alternative methods to manage pests and diseases that reduce or avoid the use of drugs and chemicals. The US Department of Agriculture has a programme for sustainable agriculture, the Sustainable Agriculture Research and Education programme, which emphasises alternative approaches for animal and plant production systems.

Identification of oxide layers of commercially pure titanium in response to cleaning procedures.

The composition and thickness of the oxide formed on commercially pure titanium disks were analyzed after the disks were subjected to one of four surface treatments: (1) cleaning with the initial Brånemark regimen, (2) Brånemark regimen and autoclaving, (3) Brånemark regimen and radiofrequency glow discharge (RFGD) treatment for 5 minutes, and (4) Brånemark regimen and RFGD treatment followed by storage for 30 days. Electron spectroscopy for chemical analysis showed titanium dioxide to be the prominent oxide; no significant differences in the thickness of the oxide layers were found.

Effects of palladium addition on emission of mercury vapor from dental amalgam.

OBJECTIVES: The purpose of this investigation was to test the hypothesis that palladium causes a reduction in mercury emission when added to dental amalgam during condensation. METHODS: Mercury vapor release was measured in a closed bottle system and an Intraoral Flow device(IOF). Conventional amalgam restorations were modified by addition of various palladium pellets. 1.57 mm diameter palladium pellets with different porosities were fabricated. These pellets were then placed in amalgam restoration using typical condensation and carving procedures. The samples were stored in a closed bottle and mercury measurements were taken from the bottles at 30 min, 1, 3, 5, 24 and 48 h and 7 days after trituration using a Jerome 411 Mercury Vapor Analyzer (Arizona Instrument Corp., Jerome, AZ). The palladium pellets identified as the most effective in mercury vapor reduction were further tested in an IOF device. Data were analyzed by two-way ANOVA followed by Tukey HSD pairwise analysis for significant findings (alpha = 0.05). RESULTS: The palladium containing amalgams when tested in the closed bottle system yielded significantly lower (p < 0.05) mercury vapor release than the controls. Pellets fabricated with the highest porosity yielded the greatest reduction in overall mercury vapor release. In the IOF device the overall amount of mercury vapor released from the palladium containing amalgams was also significantly less than the control (p < 0.05). SIGNIFICANCE: Mercury vapor emission from dental amalgam was greatly reduced by adding palladium pellets to amalgam during condensation. These techniques require only slight modifications of the standard operative procedures.

Effect of dopamine agonists or antagonists, TRH, stress and piglet removal on plasma prolactin concentrations in lactating gilts.

The effect of dopamine agonists (ergocryptine), antagonists (chlorpromazine, haloperidol, reserpine, pimozide), thyrotropin releasing hormone or stress (restraint, piglet removal) on prolactin release was studied in primiparous lactating gilts. All animals were fitted with surgically implanted jugular catheters before farrowing. The only drug treatments which resulted in a significant change in PRL concentrations in blood were thyrotropin releasing hormone (increase) and ergocryptine (decrease). The results suggest that dopamine may not be the only regulator of prolactin in lactating pigs. Further studies are needed to identify drugs which would be useful in clinical situations for treatment of lactation failure due to low prolactin secretion. In the two stress-exposed groups, there was a gradual, steady decline in the plasma concentration of prolactin which resulted from loss of suckling contact with the piglets. Thus, snare restraint does not increase prolactin secretion in lactating sows confirming the results of other studies on pigs in different physiologic states.

Steroid synthesis by the fetal part of the bovine placenta of late pregnancy in vitro: Effect of a low dose of dexamethasone in vivo.

Pregnant cows were treated with 5 mg dexamethasone (DEX) (n = 5) or 0.9% saline (n = 3) on Day 255 of gestation. Placentomes were removed on Day 250, Day 260 by laparotomy, and immediately after parturition. Fetal placental tissue (500 mg) was homogenized and frozen for the determination of initial tissue content of progesterone (P(4)) and estrone (E(1)) by radioimmunoassay (RIA). Tissue samples (500 mg) were incubated for 1, 5, or 9 h in the presence of 0, 10, or 100 ng/ml androstenedione (A) or pregnenolone (P(5)). After incubation, tissue was homogenized in the incubation medium (HOM) and P(4) and E(1) content assessed by RIA. Finally, tissue was incubated in medium containing (3)H-A or (3)H-P(5) with or without cortisol (70 ng/ml) to measure conversion of precursors into estrogens (E). Overall initial tissue concentration of P(4) decreased as pregnancy progressed (P < 0.05). An interaction between DEX treatment and stage of gestation (P < 0.05) indicated that P(4) decreased only in tissue from DEX-treated cows, whereas P(4) in tissue from control cows remained constant. Tissue concentrations of E(1) increased from Day 250 to parturition (P < 0.05) and were not influenced by in vivo DEX treatment. Progesterone concentration in HOM increased during incubation indicating P(4) synthesis (P < 0.001). Addition of 100 ng/ml P(5) stimulated P(4) production (P < 0.05). There was a larger increase in P(4) in HOM from DEX-treated cows than in HOM from control cows (P < 0.05). Concentration of E(1) decreased during incubation (P < 0.0001) and was not influenced by the addition of A or P(5). Estrogen synthesis was indicated by the conversion of A or P(5) into E (pmol/g/h). The conversion of precursors (A or P(5)) into E increased during gestation and was not influenced by in vivo DEX treatment. Cortisol application in vitro did not affect E synthesis. It is concluded that treatment with 5 mg DEX in vivo on Day 255 of pregnancy does not seem to influence placental E synthesis in vitro. However, the decrease in initial P(4) tissue concentration and the increase in P(4) synthesis by fetal placental tissue from DEX-treated cows in vitro suggest that DEX treatment in vivo stimulates P(4) synthesis with increased metabolism of P(4) into other metabolites.

Uterine motility in the cow during the estrous cycle. II. Comparative effects of prostaglandins F(2alpha), E(2), and cloprostenol.

Intrauterine pressure (IUP) changes were recorded in nonlactating, cyclic dairy cows using transcervically placed intraluminal pressure microtransducers. Spontaneous activity was recorded for the first 30 min. Prostaglandins (PG) F(2alpha) (5 mug/kg), E(2) (5 mug/kg), or cloprostenol (0.1 mug/kg) were then injected intravenously (i.v.) at diestrus, proestrus, estrus, and metestrus, and their effects were recorded. The drug administrations did not alter the duration of the estrous cycle of the cows. Single doses of PGF(2alpha) and E(2) significantly increased uterine activity at all stages of the estrous cycle, while cloprostenol had no effect. PGF(2alpha) and PGE(2) increased IUP, frequency, and amplitude during all stages of the estrous cycle. The spontaneous pattern resumed within 20 min postinjection. Partial uterine refractoriness occurred with both PGs. The results indicate that low doses of natural prostaglandins stimulate uterine activity during the estrous cycle in cattle.

Adrenal-gonad interactions in cattle. Corpus luteum function in intact and adrenalectomized heifers.

To determine the effect of the hyperadrenal state on corpus luteum (CL) function, we treated intact and adrenalectomized (ADRX) heifers with adrenocorticotropin (ACTH) and hydrocortisone. ACTH treatment of intact heifers by infusion of 1 mg alpha 1-24 ACTH/24 hr from day 2 to 25 of an estrous cycle increased progesterone concentrations in plasma to 4 +/- .52 ng/ml plasma on days 3 to 4. Thereafter, progesterone concentrations declined, indicating severe suppression of CL function as compared to that of control heifers. Similar infusions of ACTH to ADRX heifers did not alter CL function as reflected by progesterone concentrations in jugular plasma. Infusion of ADRX animals with hydrocortisone succinate (100 mg/24 hr) decreased progesterone in plasma during the cycle, with maximum values averaging less than 4 ng/ml, compared to concentrations of 6 to 7 ng/ml in control ADRX heifers. Chronic administration of ACTH or hydrocortisone to heifers caused a decreased progesterone secretion during the luteal phase of the estrous cycle. On the basis of these results, we suggest that stress, as indicated by the hyperadrenal state, could inhibit progesterone secretion by the corpus luteum.

Effect of Escherichia coli endotoxin and thyrotropin-releasing hormone on prolactin in lactating sows.

Primiparous gilts were given subcutaneous injections of saline solution or 8 mg of Escherichia coli endotoxin (055:B5 strain) in saline solution on postpartum days (PPD) 2 and/or 6 and saline solution at the same site on PPD 1, 3, 5, and 7 at 1000 hours. On PPD 1 to 3 and on PPD 5 to 7, pigs were given 100 micrograms of thyrotropin-releasing hormone (TRH) IV at 1300 hours to evaluate TRH-induced prolactin (PRL) release. Blood samples were analyzed for PRL, cortisol, triiodothyronine (T3), and tetraiodothyronine (T4) concentrations. Rectal temperatures were monitored at hourly intervals between 0800 and 1500 hours on PPD 2 and 6. The PRL declined after endotoxin administration on PPD 2, but a similar decline was not seen after saline solution administration on PPD 1, 2, or 3. The PRL concentrations remained unchanged on PPD 5, 6, and 7 in gilts exposed to endotoxin for the 1st or 2nd time on PPD 6 and to saline solution on PPD 5 and 7. The TRH injection caused increases in PRL in all animals, but the PRL increase after TRH injection was significantly lower (P less than 0.05) in gilts treated with endotoxin on PPD 2. Cortisol concentrations increased after endotoxin exposure on PPD 2 and 6. Rectal temperatures increased after endotoxin exposure on PPD 2 and 6 with peak temperatures of 41.8 C and 41.6 C seen 4 and 3 hours, respectively, after endotoxin injection. The T3 and T4 response, used as an indicator of TRH perfusion of the adenohypophysis, was unchanged after endotoxin or saline solution administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of arachidonic acid metabolites and steroids on function of bovine polymorphonuclear neutrophils.

Polymorphonuclear neutrophils (PMN) from 4 ovariectomized healthy cows were incubated with 0 (control), 10(-8), 10(-7), and 10(-6) M arachidonic acid metabolites of the cyclo- and lipoxygenase pathways for 30 minutes, and with steroids for 2 hours. Immediately after incubation, PMN were subjected to the following function assays: chemotaxis against zymosan-activated serum, chemotaxis against arachidonic acid metabolite or steroid at the doses given (only control PMN were tested), random migration, ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus (125I-IdUR-S aureus), iodination of proteins, cytochrome C reduction, antibody-independent and -dependent cell-mediated cytotoxicity (AICC and ADCC). Prostaglandin F2 alpha was chemoattractant and stimulated ingestion of 125I-IdUR-S aureus. Prostaglandin E2 stimulated cytochrome C reduction, whereas prostacyclin inhibited iodination of proteins. Thromboxane B2 stimulated ADCC. Leukotriene B4 was chemoattractant for bovine PMN and stimulated random migration and AICC. 5-Hydroxyeicosatetraenoic acid was also chemoattractant, but inhibited ingestion of 125I-IdUR-S aureus. 15-Hydroxyeicosatetraenoic acid was chemoattractant and decreased ADCC. Lipoxin A4 stimulated random migration, whereas lipoxin B4 inhibited chemotaxis against zymosan-activated serum, but was chemoattractant and stimulated cytochrome C reduction. 12-Hydroxyhepadecatrienoic acid and 12-hydroxyeicosatetraenoic acid did not influence any of the PMN functions tested. Of the steroids tested, cortisol increased ADCC, and progesterone stimulated cytochrome C reduction, but decreased ADCC. 17 beta-Estradiol and estrone were chemoattractant and stimulated cytochrome C reduction. In addition, estrone also stimulated random migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Function of neutrophils and chemoattractant properties of fetal placental tissue during the last month of pregnancy in cows.

Neutrophils were isolated from the blood of pregnant cows on days 255, 265, and 275 of pregnancy, and on the day of parturition (n = 5/group), and in addition, simultaneously from 4 ovariectomized healthy cows (control animals). Neutrophils were subjected to neutrophil function assays (chemotaxis against zymosan-activated serum, random migration, ingestion of 125I-iododeoxyuridine [IdUR]-labeled Staphylococcus aureus, iodination of proteins, cytochrome C reduction, antibody-independent and antibody-dependent cell-mediated cytotoxicity). Results were expressed as percentage of control animals. Fetal placental tissue (cotyledon), uterine wall tissue, and skeletal muscle were obtained from the principal animals on the aforementioned days via laparotomy, and tissue suspensions were prepared. Chemotaxis of neutrophils was tested against tissue supernatants. Compared with day 255, there was an increase in ingestion of 125I-IdUR-S aureus at parturition, whereas iodination of proteins and cytochrome C reduction were reduced on the day of calving. The other neutrophil functions tested did not change over time of gestation. Fetal placental and uterine wall tissue attracted neutrophils with uterine wall tissue having a tendency to be more potent than cotyledonary tissue. Skeletal muscle tissue did not attract neutrophils. There was no change in chemotaxis response of neutrophils evoked by intrauterine and uterine tissues over time of gestation. It was concluded that at parturition, neutrophil function is impaired with respect to their bactericidal effects, which may render the animal more susceptible to bacterial infections, and that the chemoattractant properties of fetal placental and uterine wall tissues are tissue-specific, at least when compared with skeletal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of cortisol and different steroidogenic pathways on estrogen synthesis by the bovine placenta.

The influence of cortisol on estrogen synthesis by the bovine placenta and the importance of the delta 4 and delta 5 pathway for estrogen production were investigated. For experiment 1, portions of fetal villi (200 mg) were incubated for 48 hours with 0, 10, 100, and 1,000 ng of cortisol/ml with [3H]androstenedione (3H-A) or [3H]pregnenolone (3H-P5). Villi were also incubated for 4, 28, and 52 hours with or without cortisol (500 ng/ml) and with 3H-A or 3H-P5 (experiment 2). The conversion of various [3H]steroid metabolites such as A, P5, 17 alpha-OH-pregnenolone (17 alpha-OH-P5), progesterone (P4), 17 alpha-OH-P4, cholesterol (chol), and chol plus lipoprotein (500 micrograms/ml) into estrogen was measured during a 4-hour incubation (experiment 3). In experiment 1, cortisol increased conversion of 3H-A and 3H-P5 into estrogen by 3 to 41% and 7 to 34%, respectively, in a dose-dependent manner (P less than 0.05). In experiment 2, times of incubation did not influence conversion of 3H-A into estrogen, which, however, was increased significantly (P less than 0.05) over all times of incubation by administration of 500 ng of cortisol/ml. Conversion of 3H-P5 into estrogen increased over time of incubation and was stimulated by cortisol (P less than 0.05). However, there was no interaction between cortisol treatment and time of incubation. In experiment 3, conversion of 3H-A, 3H-P5, and 3H-17 alpha-OH-P5 into estrogen was greater than the conversion of the other precursors tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Depression of polymorphonuclear leukocyte function associated with experimentally induced Escherichia coli mastitis in sows.

In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection.

Influence of conditioned media from bovine cotyledon tissue cultures on function of bovine neutrophils.

Bovine fetal placental (cotyledon) tissue obtained from pregnant cows on days 255, 265, and 275 of gestation, as well as immediately after parturition (n = 5) was incubated in media for 48 hours, and the incubation media were collected. Neutrophils from 4 ovariectomized nonpregnant cows were incubated for 2 hours with conditioned media from placental tissue cultures or medium (control). Immediately after incubation, the neutrophils were subjected to the following leukocyte function assays: chemotaxis against zymosan-activated serum, chemotaxis against undiluted conditioned media (only neutrophils that were incubated in medium only), random migration, ingestion of 125I-iododeoxyuridine Staphylococcus aureus (125I-IdUR-S aureus), iodination of proteins, cytochrome C reduction, and antibody-independent and -dependent cell-mediated cytotoxicity. Conditioned media from cultured cotyledon tissue was chemoattractant for bovine neutrophils, and increased chemotactic response of neutrophils against zymosan-activated serum by 13%. The following neutrophil functions were decreased: random migration by 25%, iodination of proteins by 44%, cytochrome C reduction by 13%, and antibody-dependent cell-mediated cytotoxicity by 5%. Ingestion of 125I-IdUR-S aureus and antibody-independent cell-mediated cytotoxicity were not influenced by coincubation of neutrophils and conditioned media. Time of gestation did not alter the effects of conditioned media on neutrophil function. It was concluded that chemotactic properties of cotyledon tissue extracts, as has been reported earlier, may be attributable to substances released by fetal placental tissue. Those substances might also locally or systemically influence the oxygen-dependent antimicrobial system of neutrophils, thereby causing an increased susceptibility to bacterial infections in the peripartum period.

Seasonal effects of tropical climate on shaded and nonshaded cows as measured by rectal temperature, adrenal cortex hormones, thyroid hormone, and milk production.

Rectal temperatures and hormone concentrations were monitored at intervals of 2 to 3 weeks, and milk, milk fat, and California mastitis test scores at intervals of 1 week in five shaded and in four nonshaded early lactation cows. Measurements were taken from September to December in the mildly heat stressing climate of Oahu, Hawaii. The daily ambient temperature flux ranged from 22 C to 29 C in September to 20 C to 25 C in December. Average daily temperature-humidity index (THI) values were 75 to 70 for September and December, respectively. Average daily THI values were correlated with rectal temperatures in nonshaded cows and were negatively correlated with plasma adrenal cortex hormones (corticoids) in shaded cows, plasma thyroid hormone in shaded and nonshaded cows, and with milk production in nonshaded cows. Estimated milk production decline per unit increase in THI was 0.32 kg. Nonshaded cows had higher rectal temperatures, a trend for lower plasma corticoids, produced less milk and milk fat, and had higher California mastitis test scores. Shaded cows maintained a higher fat percentage at THI above 74. Average plasma thyroid hormone values were not different between treatment groups. Both groups failed to attain normal rectal temperatures at night. Afternoon rectal temperatures were more highly correlated with the rectal temperature with which the cow started the day than they were with the THI of the day itself.

Progesterone secretion by the bovine fetoplacental unit and responsiveness of corpora lutea to steroidogenic stimuli at two stages of gestation.

To evaluate the response of luteal cells to in vitro stimulation with luteinizing hormone (LH) or dibutyryl cyclic adenosine monophosphate (dbcAMP) and determine the secretion of progesterone by the fetoplacental unit, the corpora lutea were removed surgically in 10 cows (luteectomy) at 250 days (5 cows) or 270 days (5 cows) of gestation. During surgery, but before luteectomy, catheters were placed in the middle uterine artery and vein, carotid artery, and jugular vein. Blood samples were collected from all catheters just before luteectomy and at 8-hour intervals after luteectomy for 72 hours or until calving, whichever occurred first. Luteal tissue was prepared as a dispersed cell preparation and incubated with 0, 0.1, 1.0, 10, or 100 ng of LH/ml of medium or was incubated with 0, 0.5, or 2 mM dbcAMP. Synthesis of progesterone in response to LH by dispersed cells prepared from corpora lutea at 270 days was less (P less than 0.01; analysis of variance) than that by similar preparations at 250 days because a dose-response relationship was not observed for incubations of luteal tissue with LH at 270 days of gestation. Progesterone synthesis in response to the addition of dbcAMP also was less (P less than 0.01) at 270 than at 250 days of gestation. This difference in responsiveness to LH and dbcAMP between the 2 stages of gestation was not reflected by a significant difference between stages of gestation in systemic concentrations of progesterone before luteectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of estrone infusion on secretion of F series prostaglandins and on function of the corpus luteum during late gestation in cattle.

Catheters were surgically implanted in the carotid artery, jugular vein, and middle uterine vein of 8 cows at 245 days of gestation. Four cows were given 4 mg of estrone/hour via continuous jugular infusion from 0800 hours on day 246 of gestation through 0800 hours on day 250 of gestation; the remaining 4 cows (controls) were given the vehicle for estrone at 10 ml/hour for the same period. Blood samples were collected from the carotid artery every 3 hours during the infusion. Samples were collected hourly from the middle uterine vein from 0 through 8, 54 through 66, and 112 through 120 hours of the infusion periods. After completion of the infusion, corpora lutea were enucleated and blood samples were collected from the carotid artery and uterine vein at hourly intervals for an additional 8 hours. Dispersed cell preparations of the corpora lutea were incubated with and without luteinizing hormone (LH) or dibutyryl cyclic adenosine monophosphate (dbcAMP). Circulating concentrations of unconjugated and conjugated estrone and estradiol-17 beta were higher (P less than 0.05) in the group infused with estrone than in the vehicle-infused group. Mean and base-line concentrations of F series prostaglandins (PGF) for each blood collection period tended to increase (P less than 0.10) during infusion with estrone, but not during infusion with vehicle. After luteectomy, mean and base-line concentrations of PGF also tended (P less than 0.10) to be greater in the estrone-infused cows than in the control cows, but a surge in PGF concentrations due to removal of the ovarian source of progesterone did not develop.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of edetate and thiamine for treatment of experimentally induced environmental lead poisoning in cattle.

Twenty mature Holstein cows were randomized into 5 treatment groups. Cows of groups 2 to 5 were given 2 mg of elemental Pb/kg of body weight for 28 days. Clinical signs of plumbism were scored, and blood for Pb, progesterone, and hematologic analyses was collected weekly. Cows also were examined weekly for anomalous ovarian cycles. Starting on study day 28, cows in group 3 were treated once daily with 2 mg of thiamine HCl/kg (IM) for 13 days, cows in group 4 were treated twice daily with 62 mg of Na2,Ca-EDTA/kg (IV) for 4 days, and cows in group 5 were given thiamine (dosage regimen the same as for group 3) plus Na2,Ca-EDTA (dosage regimen the same as for group 4). On study days 96 through 139, cows were slaughtered in a commercial abattoir and samples of blood, skeletal muscles, bones, liver, and kidneys were collected and assayed for Pb concentration. Thiamine was not effective in reducing blood Pb concentration, and treatment with Na2,Ca-EDTA and thiamine plus Na2,Ca-EDTA was effective in reducing the concentration of Pb in blood. However, treatment with thiamine was more effective than treatment with Na2,Ca-EDTA or thiamine plus Na2,Ca-EDTA in inducing remission of clinical signs of plumbism. The concentration of Pb in blood was significantly (P less than 0.05) correlated to the concentration of Pb in liver, kidneys, skeletal muscles, and bones. Significant (P less than 0.05) relationship existed between number of days from Pb exposure to slaughter and concentration of Pb in blood, liver, and skeletal muscles. Exposure to Pb did not significantly alter CBC values.(ABSTRACT TRUNCATED AT 250 WORDS)

Association between neutrophil functions and periparturient disorders in cows.

Neutrophil functions were examined in healthy periparturient dairy cows (n = 46) and in cows with retained placenta and metritis complex (n = 20); metritis (n = 18); or mastitis (n = 13). Blood samples (50 ml) were collected from each cow via jugular vein twice weekly from 1.5 weeks before to 4 weeks after parturition. Neutrophil function was evaluated, using 6 tests: random migration, chemotaxis, ingestion, myeloperoxidase activity (iodination), superoxide production (cytochrome C reduction), and antibody-dependent cell-mediated cytotoxicity. Ability to ingest bacteria and random migration activity of neutrophils from clinically normal cows were high around parturition and increased immediately after parturition, whereas myeloperoxidase activity and antibody-dependent cell-mediated cytotoxicity ability of neutrophils from these cows decreased after parturition. Measurement of neutrophil function in 4 ovariectomized cows revealed significant (P < 0.0005) seasonal changes in results of all 6 functional assays. We observed various defects of neutrophil function in all cows with abnormal conditions after parturition. Before parturition, superoxide production activity by neutrophils from cows with metritis and chemotaxis by neutrophils from cows with mastitis were significantly (P < 0.001 and P < 0.05, respectively) lower, indicating that a defect of neutrophil function may be a predisposing factor in the development of these disorders. In conclusion, the host defense role of neutrophils in periparturient cows was impaired, principally because of a defect in killing capacity, which may increase susceptibility to infections. We also investigated the in vitro effects of arachidonic acid metabolites and recombinant human colony-stimulating factors (rhCSF) on functions of neutrophils from clinically normal and postparturient cows with abnormalities, including retained placenta, metritis, or mastitis (n = 5/group). Each abnormal cow was matched for postpartum period with a clinically normal cow. Neutrophils from individual cows were preincubated with arachidonic acid metabolites (prostaglandin F2 alpha, 10(-7) M; prostaglandin E2, 10(-6) M; leukotriene B4, 10(-8) M; and lipoxin B, 10(-8) M) and rhCSF (rh-granulocyte-CSF, 1,000 or 6,000 U/ml; rh-granulocyte-macrophage-CSF, 5 or 15 ng/ml) in a 37 C water bath for 30 minutes before submitting them to function assays. There was no response by neutrophils from either clinically normal or abnormal postparturient cows to treatment with either arachidonic acid metabolites or rhCSF in any of the 6 functional assays. However, preincubation of neutrophils alone in a 37 C water bath for 30 minutes resulted in some alteration of neutrophil function.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of chlorpyrifos on Holstein steers and testosterone-treated Holstein bulls.

The effect of chlorpyrifos application was studied in a high-testosterone (testosterone-treated bulls) and a low-testosterone group (corn oil-treated steers). Frequent sampling of blood before and after 2 chlorpyrifos applications was used to monitor plasma testosterone concentrations and blood cholinesterase activities. Bulls had significantly higher testosterone concentrations (P less than 0.01) than did the steers, before and after the 1st and 2nd chlorpyrifos applications. Bulls had higher cholinesterase activities (P less than 0.01) than did steers before the 1st chlorpyrifos application. However, cholinesterase activity decreased more in bulls when compared with that in steers (P less than 0.01) after the 1st and 2nd chlorpyrifos application. Abnormal clinical signs were not observed in the steers, but 2 of 4 bulls had severe clinical signs of organophosphorus insecticide toxicosis after the 2nd application. Seemingly, chlorpyrifos is more toxic for testosterone-treated bulls than for corn oil-treated steers of similar age and weight.