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At least 73 records · Page 4Linked to original sources
PubMed1990

Suppressed peripheral blood lymphocyte blastogenesis in pre- and postpartal sheep by chronic heat-stress, and suppressive property of heat-stressed sheep serum on lymphocytes.

Phytohemagglutinin (PHA) and concanavalin A (Con A)-induced blastogenesis of peripheral blood lymphocytes was examined in heat-stressed pre- and postpartal sheep. The peak responses of lymphocytes to PHA and Con A in heat-stressed sheep revealed significant reduction before and after parturition compared with those in the corresponding control animals kept under thermoneutral conditions. Furthermore, the effect of serum from control or heat-stressed sheep on PHA-induced lymphocyte blastogenesis was examined. Supplementation of serum from heat-stressed sheep significantly suppressed the blastogenesis of lymphocytes obtained from healthy sheep, bovine, and human donors. Unlike dexamethasone, heat-stressed sheep serum did not inhibit IL-2 production by PHA-stimulated human peripheral blood lymphocytes. These results indicate that the immunosuppression of heat-stressed sheep is in part mediated by serum factor(s) that can modulate T-cell function in a species nonspecific manner.

Animals↗
PubMed1986

Characterization of two mouse myeloma X sheep lymphocyte cell lines secreting sheep antibody.

Two mouse X sheep interspecific cell hybrids were obtained by fusing mouse myeloma cell line Sp2/O. Ag14 with sheep lymphocytes obtained from a lymph node antigenically stimulated with azo-benzene arsonate-ovalbumin (ABA-ova). The interspecific cell lines were characterized using immunochemical, karyotypic and molecular DNA techniques. Both cell lines secreted sheep IgG1 antibody specific for the ABA haptenic determinant. Karyotypic analysis revealed that cell lines 4.11 and 11.9 had modal chromosome numbers of 91 and 106, respectively. Although C-banded spreads confirmed that fusion between sheep and mouse cells had occurred, it was not possible to differentiate sheep from mouse chromosomes. However, DNA hybridization techniques showed that each line contained sheep repetitive sequence DNA. It was calculated that cell line 11.9 contained 17640 copies while cell line 4.11 contained 734 copies of the previously characterized sheep satellite DNA.

Animals↗
PubMed2001

Experimental transmission of sheep-associated malignant catarrhal fever from sheep to Japanese deer (Cervus nippon) and cattle.

The assumption that sheep carry ovine herpesvirus-2 (OvHV-2), the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), is widely accepted, albeit OvHV-2 has not been isolated. We attempted experimental contact transmission of MCF from Japanese sheep persistently infected with OvHV-2 to Japanese deer (Cervus nippon) and cattle. In Experiment 1, a deer was kept in close quarters with an infected ewe. In Experiment 2, a second deer was kept with the same ewe. In Experiment 3, two cows were each kept with two infected wethers. In Experiment 1, the deer developed clinical signs at 138 days after first contact and then died. OvHV-2 genes by polymerase chain reaction (PCR) and fluorescent antibodies to Alcelaphine herpesvirus-1 were detected in the affected deer. Moreover, sequences of PCR products (423bp), obtained by amplification of materials from the sheep and from the affected deer, coincided. These results clearly confirmed that the sheep was a carrier of OvHV-2, and that this virus had induced SA-MCF in a deer. In other experiments, no OvHV-2 infection occurred in deer and cattle during the 6-18 months periods of contact, though viral genes were detected in the nasal swabs and white blood cells of the sheep. To our knowledge, this is the first report on successful experimental transmission of MCF from OvHV-2-infected sheep to deer.

Animals↗
PubMed2000

Serum pharmacokinetics of oxytetracycline in sheep and calves and tissue residues in sheep following a single intramuscular injection of a long-acting preparation.

The pharmacokinetics of a long-acting oxytetracycline (OTC) formulation (Liquamycin LA-200) injected intramuscularly (i.m.) at a dose of 20 mg/kg were determined in four calves and 24 sheep to determine if the approved label dose for cattle provided a similar serum time/concentration profile in sheep. The AUC for the calves was 168+/-14.6 (microg ? h/mL) and was significantly less than the AUC for sheep (209+/-43 microg ? h/mL). Using the standard two-stage approach and a one-compartment model, the mean Cmax for the calves was 5.2+/-0.8 microg /mL, and for the sheep was 6.1+/-1.3 microg /mL. The mean terminal phase rate constants were 0.031 and 0.033 h, and the Vdss were 3.3 and 3.08 L/kg for the calves and sheep respectively. Analysis of the data using the standard two-stage approach, the naive pooled-data approach and a population model gave very similar results for both the cattle and sheep data. Sheep tissue residues of OTC in serum, liver, kidney, fat, muscle and injection site were measured at 1, 2, 3, 5, 7 and 14 days after a single i.m. injection of 20 mg/kg OTC. Half-lives of OTC residues in the tissues were 38.6, 33.4, 28.6, 25.4, 21.3, and 19.9 h for injection site, kidney, muscle, liver, mesenteric fat and renal fat, respectively. The ratio of tissue to serum concentration was fairly consistent at all slaughter times, except for the fat and injection sites. The mean ratios were 1.72, 4.19, 0.11, 0.061, 0.84 and 827 for the liver, kidney, renal fat, mesenteric fat, muscle and injection sites, respectively. The tissue concentrations of OTC residues were below the established cattle tolerances for OTC in liver (6 p.p.m.), muscle (2 p.p.m.) and kidney (12 p.p.m.) by 48 h, and in injection site muscle by 14 days after the single i.m. injection of 20 mg/kg.

Animals↗
PubMed2000

Generation of sheep X (sheep X mouse) heterohybridoma cell line expressing the beta-1 integrin membrane molecule.

Sheep are an important biological model in such diverse areas as immunology and reproductive biology. The limitation of sheep as an experimental model is the absence of reliable cell lines. To establish cell lines that express functional sheep membrane molecules, we produced a sheep x mouse heterohybridoma by fusion of sheep efferent lymph T cells with the murine myeloma cell line NS1. A cloned heterohybridoma fusion partner was selected by treatment with 8-azaguanine. The resulting cell line HL1/385 was selected for hypoxanthine/aminopterin/thymidine (HAT) sensitivity and growth efficiency. The HL1/385 cell line was used as a back-fusion partner into lectin-stimulated efferent T lymphocytes. The back-fusion approach produced more than 50 heterohybrid cell lines with high growth efficiency. The expression of physiological levels of the sheep beta-1 integrin cell surface molecule on the HT4/6 cell line was stable for months in culture. These results suggest that somatic heterohybrids may provide a reliable source of cell lines for sheep studies in vitro.

Animals↗
PubMed1977

G-band patterns of the Siberian snow sheep (Ovis nivicola) and their relationship to chromosomal evolution in sheep.

G-band patterns of the Siberian snow sheep, Ovis nivicola alleni, 2n=52, were compared with the patterns reported in 2n=54 wild Asiatic mouflon and 2n=54 North American sheep and those in domestic sheep with 2n=54, 53, and 52. The three largest pairs of biarmed autosomes displayed indistinguishable, presumably homologous, G-banding patterns in all types of sheep. The banding and morphology of the fourth pair of biarmed autosomes in O.nivicola differed from those of the three translocation variants described in domestic sheep. Wild sheep with 2n=54 may have evolved monophyletically from an ancestral 2n=58-56-54 population or polyphyletically by a series of independent, nonrandom fusions. In contrast, the fouth pair of biarmed autosomes in O.nivicola and in 2n=52 domestic sheep variants may have resulted from random fusions of different chromosomes.

Animals↗
PubMed1975

The relation between the rabbit potency test and the response of sheep to sheep clostridial vaccines.

Six commercially available clostridial vaccines comprising one oil-emulsion, two alum-precipitated and three aluminum hydroxide adjuvanted preparations, each containing between two and seven antigenic components, were administered to groups of 10 rabbits and eight sheep in accordance with manufacturers' recommendations. Serum antitoxic values to Cl welchii beta, Cl welchii epsilon, Cl septicum, Cl oedematins and Cl tetani toxins were determined 14 days after completion of each vaccination course. The overall pattern of mean antitoxic values was found to be similar in sheep and rabbits, a vaccine eliciting a comparatively high antibody titre to any given antigen component in sheep also inducing a comparatively high titre in the corresponding group of rabbits. Similarly, comparatively poor responses in sheep were associated with poor responses in rabbits. The degree of variation in response within groups of animals was greater in sheep than in rabbits for all five antigenic components assayed. Sheep consistently developed higher titres than rabbits to Cl oedematins component but consistently lower titres to both Cl welchii beta and epsilon components irrespective of the type of vaccine used. The response of both species to Cl tetani antigen was similar in terms of serum antitoxic values. It was concluded that rabbits provide a suitable model for the assessment of potency of sheep clostridial vaccines.

Adjuvants, Immunologic↗
PubMed1985

Variations in sheep serum conglutinating complement activity and pathway involved in reactivity with sheep erythrocytes sensitized by rabbit antibody.

Based on conglutination tests with the sheep E-rabbit A indicator system, three types of sheep sera were encountered. Type 1 sera failed to directly conglutinate or sensitize sheep E-rabbit A for conglutination by bovine conglutinin. Type 2 sera also failed to directly conglutinate sheep E-rabbit A but sensitized the indicator for conglutination by bovine conglutinin. Type 3 sera both directly conglutinated and sensitized sheep E-rabbit A for conglutination. Changes in serum type were induced in sheep by venepuncture (type 1 to type 2) or venepuncture and an intraperitoneal injection of yeast cells (type 2 to type 3). Direct conglutinating activity of type 3 sera was inhibited by heating serum at 50 degrees C for 30 min and was not restored by alternative activation pathway factor B. Chelation of Ca2+ in type 2 and 3 sera blocked sensitization of sheep E-rabbit A for conglutination by bovine conglutinin, indicating that the classical activation pathway was involved.

Acetylglucosamine↗
PubMed2006

Immune responses to Staphylococcus aureus and Psoroptes ovis in sheep infected with P. ovis--the sheep scab mite.

In sheep, lesions caused by Psoroptes ovis, the sheep scab mite, may become colonized by Staphylococcus aureus. The present study compares clinical signs, lesional area and the immune response to P. ovis and S. aureus in P. ovis-infested sheep with and without secondary S. aureus infection. No differences were detected in the clinical signs or lesional areas in the S. aureus-positive and -negative sheep. However, 6 weeks after infestation an IgG but not IgE isotype antibody response to S. aureus was detected in the S. aureus-positive but not the S. aureus-negative group of sheep. This response targeted S. aureus antigens with molecular weights of approximately 36, 38, 50 and 65 kDa. In addition, 6 weeks after infestation an IgE response to P. ovis was detected in the S. aureus-positive but not the S. aureus-negative group of sheep.

Animals↗
PubMed1999

The distribution of pepsinogen within the abomasa of cattle and sheep infected with Ostertagia spp. and sheep infected with Haemonchus contortus.

The effect of nematode infections on the production of pepsinogen by ruminants was investigated immunohistochemically and biochemically. Abomasal tissues were collected from parasite-naive cattle and sheep, from sheep infected with predominantly Ostertagia circumcincta, sheep infected experimentally with Haemonchus contortus and cattle infected with Ostertagia ostertagi. Pepsinogen was also assayed biochemically in homogenates of fundic mucosae from sheep infected with predominantly O. circumcincta. Infection with Ostertagia spp. parasites was associated mainly with nodular hyperplasia, resulting in increased numbers of cells that produce both pepsinogen and mucus. Measured biochemically, nodules contained more pepsinogen than adjacent more normal mucosa (p < 0.05), and this effect was largely attributable to the greater mass of nodules. Infection of sheep with H. contortus was associated with generalised hyperplasia, characterised by increased numbers of mucopeptic cells and in at least one animal with reductions in parietal cell numbers. At the same time, the zymogen granule content of chief cells was reduced. Similar changes were occasionally seen in sheep infected predominantly with O. circumcincta. Generalised hyperplasia is likely to be indicative of the presence of ambulatory parasitic stages as opposed to those confined to nodules. The potential for the enhanced production of pepsinogen by increased numbers of cells with a joint mucous cell and zymogenic cell phenotype may offset decreases in the numbers of chief cells or reductions in chief cell activity.

Abomasum↗
PubMed1992

The influence of challenge dose, duration of immunity, or steroid treatment on mucosal mast cells and on the distribution of sheep mast cell proteinase in Haemonchus-infected sheep.

The distribution of granule-specific sheep mast cell proteinase (SMCP), was assayed by immunocytochemistry and quantified by immunoassay in sheep immune to Haemonchus contortus. Repeated infection with Haemonchus larvae over 10-12 weeks induced a pronounced mucosal mastocytosis, including intraepithelial globule leukocytes (GL), which, 7 days after ceasing this dosing regime, was associated with the inability of incoming larvae to establish within the abomasal mucosa. Loss of this resistance, due to the cessation of stimulation with Haemonchus larvae 84 days previously or to treatment of sheep with corticosteroid, was associated with a marked decline in mast cell density and concentrations of SMCP in abomasal mucosal tissues. Nevertheless, larvae also failed to establish in immune sheep rested from challenge 42 days previously and in which mast cell counts were not significantly different from those of control sheep. A small, but significant, release of SMCP was demonstrated in gastric mucus from immune sheep following larval challenge, whereas little or no SMCP was detected in mucus from naïve animals.

Abomasum↗
PubMed2003

Susceptibility of transgenic mice expressing chimeric sheep, bovine and human PrP genes to sheep scrapie.

The use of Transgenic (Tg) mice expressing chimeric sheep/mouse (Sh/Mo) prion protein (PrP) and chimeric bovine/mouse (Bo/Mo) PrP genes was evaluated as a sheep scrapie model. We also investigated the potential for the transmission of sheep scrapie to a human/mouse (Hu/Mo) PrP Tg mouse line. The Sh/Mo PrP and Bo/Mo PrP Tg Prnp(+/+) or Prnp(0/0) mouse lines were inoculated intracerebrally with brain homogenates from three sheep with natural scrapie (KU, Y5 or S2). Incubation periods were slightly shorter in Sh/Mo PrP Tg Prnp(+/+), than in non-Tg mice inoculated with KU brain homogenate. In contrast, the incubation period was significantly prolonged (p<0.05) in Bo/Mo PrP Tg Prnp(+/+) mice inoculated with KU brain homogenate. The incubation period was significantly longer in all Tg Prnp(+/+) and Prnp(0/0), than in non-Tg mice (p<0.01) inoculated withY5 brain homogenate. None of the Tg Prnp(0/0) mice inoculated with S2 brain homogenate developed clinical signs and PrP(Sc) was undetectable in their brains. These results suggested that expression of the Sh/Mo PrP or Bo/Mo PrP transgenes does not confer susceptibility to sheep prions upon mice, and thus none of the Tg mouse lines could be a suitable model of sheep scrapie. Hu/Mo PrP Tg Prnp(0/0) mice inoculated with natural and experimental scrapie or mouse prions did not develop clinical signs of scrapie and PrP(Sc) was undetectable. These results suggested that neither sheep nor mouse strains of scrapie are highly transmissible to humans.

Animals↗
PubMed1996

[Antibiotic resistance in Staphylococcus aureus mastitis in sheep, sheep milk and its products].

A study of current resistance to antibiotics was conducted in 500 strains of Staphylococcus aureus isolated from ewes with clinical and latent mastitis, from sheep milk and products made from it (sheep lumpy cheese, bryndza cheese). A diffusion disk method was used to assay 14 kinds of antibiotics (AMP, BAC, CEF, ERY, GEN, CMP, KAN, LIN, OXA, PEN, RIF, SPI, VAN, TET) and one chemotherapeutic drug (COT). The highest resistance was observed in the cases of clinical mastitis (from 8% and 10% in COT and KAN to 68% and 69% in PEN and TET). Resistance significantly decreased in 13 kinds of antibiotics in the group of cases with latent mastitis (from 3% in SPI to 30% in PEN), it increased in KAN (13%) and COT (12%) only. Resistance also decreased in bulk samples of sheep milk; it was the highest in PEN (27%) and AMP (17%) and the lowest in CEF, RIF and SPI (5%). Sheep lumpy cheese and bryndza cheese are mostly made from unpasteurized milk. Resistance continued to decrease even in these dairy products. It ranged from 2% in CEF to 16% in OXA in sheep lumpy sugar, while it varied from 0% in SPI to 14% in TET in bryndza cheese. The results demonstrate that sheep milk and products made from it are not any important sources of antibiotic resistance of S. aureus in Central Slovakia.

Animals↗
PubMed1994

Seven loci on human chromosome 4 map onto sheep chromosome 6: a proposal to restore the original nomenclature of this sheep chromosome.

Seven new loci, casein alpha-S1 (CSN1S1), casein alpha-S2 (CSN1S2), casein beta (CSN2), the Hardy-Zuckerman 4 feline sarcoma viral (v-kit) oncogene homolog (KIT), albumin (ALB), phosphodiesterase cyclic GMP (rod receptor) beta polypeptide (PDEB), and complement component 1 (IF), were assigned to sheep Chromosome (Chr) 6 by Southern hybridization to a panel of chromosomally characterized sheep x hamster cell hybrids. By isotopic in situ hybridization, CSN2 was regionally localized to sheep Chr (OOV) 6q22-q31, anchoring this syntenic group of markers on to OOV6 and confirming its homology at a molecular and cytological level with cattle Chr 6. The assignment of these loci, from PDEB (located on human Chr 4p16.3) to IF (on HSA4q24-q25), and the observation that interleukin 2 (IL2, on HSA4q26-q27) and tryptophan 2,3-dioxygenase (TDO2, on HSA4q31) are not located on OOV6, is further evidence of the close evolutionary relationship of sheep and cattle and the conserved synteny in these species of this extensive region of human Chr 4. On the basis of this conserved synteny, and the similar G- and Q-banding patterns of this chromosome in cattle and sheep, we propose that this sheep chromosome be numbered as 6, not 4 as recommended by ISCNDA (1990).

Animals↗
PubMed1989

Human recombinant interleukin 2-activated sheep lymphocytes lyse sheep pulmonary microvascular endothelial cells.

Administration of lymphokine-activated killer (LAK) cells in combination with interleukin 2 (IL-2) has been effective in reducing tumor mass in humans, but has been accompanied by significant toxicity. We used a chronic awake sheep model to investigate the cause of the vascular leak syndrome associated with IL-2 administration. Sheep repeatedly infused with human recombinant IL-2 (hrIL-2) developed mild pulmonary hypertension, systemic hypotension, acidemia, hypoxemia, and increased flow of protein rich lung lymph. We hypothesized that LAK cells may damage lung endothelium in vivo and cause increased lung vascular permeability. Sheep peripheral blood and lung lymph lymphocytes incubated in vitro with hrIL-2 generated cytotoxic activity for human K-562 cells and sheep pulmonary microvascular endothelial cells. In addition, cytotoxic effector cells were isolated from the peripheral blood of a sheep which had received hrIL-2. These observations suggest that LAK cells possess the ability to damage endothelial cells and may contribute to an increased pulmonary vascular permeability observed following hrIL-2 infusion in sheep.

Animals↗
PubMed1981

Haemolysis of human erythrocytes heavily sensitized with sheep amboceptor by sheep complement chelated with EGTA or Mg2+-EGTA.

Human erythrocytes sensitized with an agglutinating dose of either sheep anti-human erythrocyte antiserum, IgM, slow or fast gamma-globulin antibody are haemolysed by foetal lamb or sheep serum complement (C) in the presence of ethyleneglycoltetraacetic acid (EGTA) or Mg2+-EGTA but not ethylenediaminetetraacetic acid (EDTA) or triethylenetetraminehexaacetic acid (TTHA). Dialysis of the C source against phosphate buffered saline rendered it inactive, but addition of Mg2+ or Mg2+-EGTA restored haemolytic activity. Haemolysis of sensitized erythrocytes took place more rapidly in buffer containing Ca2+ and Mg2+ than in EGTA or Mg2+-EGTA. Heating the C source at 50 degrees C for 30 min or 56 degree C for 3 min abolished haemolytic activity. In the presence of EGTA or Mg2+-EGTA, haemolytic activity was restored to 50 degrees C-heated serum by a CM-cellulose fraction that contained sheep factor B. These results show that sheep C, in the presence of EGTA or Mg2+-EGTA will haemolyse human erythrocytes heavily sensitized with sheep amboceptor. The alternative pathway of sheep C is thought to be involved.

Animals↗
PubMed1996

The amino acid sequences, structure comparisons and inhibition kinetics of sheep cathepsin L and sheep stefin B.

Cathepsin L and stefin B were isolated from sheep liver, the cathepsin L being isolated by a low pH homogenisation method, which increases the proportion of the two-chain form of the enzyme, thus facilitating sequencing. The amino acid sequences of the isolated cathepsin L and stefin B were determined. The two-chain form of cathepsin L contains 217 amino acid residues and has an M(r) of 23,627. The sequence was obtained by sequencing the native active enzyme, the light and heavy chains and the peptides generated by cyanogen bromide cleavage. These peptides were aligned with peptides obtained by hydrolysis with endoproteinase Lys-C, glycyl endopeptidase and endoproteinase Glu-C. Sheep liver cathepsin L exhibits a high degree of sequence identity to human cathepsin L. Sheep stefin B consists of 98 amino acid residues and its calculated M(r) is 11,150. The inhibitor has its NH2-terminal amino acid residue blocked. Its amino acid sequence was determined by sequencing the peptides obtained by cleavage with cyanogen bromide and peptides obtained by hydrolysis with endoproteinase Glu-C and endoproteinase Lys-C. Sheep stefin B shows a high degree of sequence identity with bovine and human stefin B. The kinetics of the interaction between sheep cathepsin L and stefin B were determined, with the interaction of stefin B with papain used as a benchmark to compare with other published results. Despite the considerable homology between bovine and sheep stefin B, the kinetics of their interaction with papain and cathepsin L differed markedly, possibly due to the differences in the so-called "trunk" region of the cystatin molecule.

Amino Acid Sequence↗
PubMed1999

Genomic characterization of the sheep vasopressin V1a receptor gene and promoter, with assignment to bands q23-24 of sheep chromosome 3 and cattle chromosome 5.

Arginine vasopressin interacts with the vasopressin type 1a receptor (V1aR) to initiate physiological effects such as vasoconstriction of blood vessels and glycogenolysis. AVP is also involved in central nervous effects such as body homeostasis and blood pressure control. The complete genomic organization of the sheep V1aR gene has been determined, including the presence of one major and two minor transcriptional start sites at -321, -206 and -91bp respectively, relative to the ATG codon. Another more distal minor transcriptional start site was also localized between nucleotides -997 and -892 relative to the ATG codon. One intron exists in the sheep V1aR gene and potential cis- and trans- acting sites were identified in the sheep V1aR promoter. The promoter was also compared to the rat V1aR promoter. The sheep V1aR promoter displays features typical of housekeeping genes, although tissue-specific expression does not support this. V1aR mRNA is absent in the adult sheep liver but not the kidney. One copy of the V1aR gene exists in the sheep genome, which was localized to chromosome 3q23-24, and to the homoeologous position, 5q23-24 in cattle.

Amino Acid Sequence↗