Equatorial X-ray Emissions: Implications for Jupiter's High Exospheric Temperatures

Observations with the High Resolution Imager on the Rontgensatellit reveal x-ray emissions from Jupiter's equatorial latitudes. The observed emissions probably result from the precipitation of energetic (>300 kiloelectron volts per atomic mass unit) sulfur and oxygen ions out of Jupiter's inner radiation belt. Model calculations of the energy deposition by such heavy ion precipitation and of the resulting atmospheric heating rates indicate that this energy source can contribute to the high exospheric temperatures(>800 kelvin at 0.01 microbar) measured by the Galileo probe's Atmospheric Structure Instrument. Low-latitude energetic particle precipitation must therefore be considered, in addition to other proposed mechanisms such as gravity waves and soft electron precipitation, as an important source of heat for Jupiter's thermosphere.     

Investigations into the toxicity of Echium plantagineum in sheep: 1. Field grazing experiments

A field grazing trial was undertaken to monitor the health and production of crossbred sheep grazing pasture where Echium plantagineum constituted a considerable proportion of the available forage. The trial, conducted for 19 months over successive grazing seasons, demonstrated a significant difference in production, with sheep on the E. plantagineum pasture being lighter and growing less wool compared with sheep on Echium-free pasture. No mortalities involving pyrrolizidine alkaloid poisoning were recorded in sheep grazing E. plantagineum, although there was histological evidence of moderately severe liver damage associated with high liver copper concentrations in at least one sheep following the grazing of large quantities of the plant.     

African horsesickness: Pathogenesis and immunity

African horsesickness (AHS) is a serious, non-contagious disease of horses and other solipeds caused by an arthropod-borne orbivirus of the family Revoiridae. In horses, AHS causes three distinct clinicopathologic syndromes, the pulmonary, cardiac and fever forms of the disease. Recent work has shown that the primary determinant of the form of disease expressed by naive horses is the virulence of the virus inoculum. Horses which recover from AHS exhibit solid humoral immunity against homologous challenge. Protective antibodies appear to be directed towards neutralizing epitopes on AHS virus VP2. The relationship of neutralization to protection and vaccination is discussed.     

Truncated gamma-glutamyl carboxylase in rambouillet sheep

A flock of Rambouillet sheep was examined because of increased lamb mortality due to ineffective hemostasis at parturition. Decreased activities of coagulation factors II, VII, IX, and X, and severely reduced hepatic gamma-glutamyl carboxylase activity with adequate vitamin K 2,3 epoxide reductase activity was determined.(1,)(21) Parenteral vitamin K(1) supplementation did not improve vitamin K-dependent coagulation factor activities in 3 affected lambs. Affected lamb gamma-glutamyl carboxylase deoxyribonucleic acid was sequenced, and 4 single nucleotide polymorphisms (SNPs 2-5) of the gamma-glutamyl carboxylase gene were identified. Single nucleotide polymorphism-4 results in an arginine to stop codon (UGA) substitution, which prematurely terminates the peptide at residue 686 (R686Stop). This genotype (GATT/GATT) has a strong association with the coagulopathy observed in clinically affected lambs, P < 0.001. The frequency of SNP-3 in exon 11 (R486H) within the MARC 1.1 database is high in the US sheep population overall. Gamma-glutamyl carboxylase activity in hepatic microsomes from a SNP-3 homozygous lamb lacking the SNP-4 mutation (GACC/GACC) was similar to control sheep homozygous for arginine at 486 and also lacking SNP-4 (TGCC/TGCC), indicating that the R486H does not measurably impact gamma-glutamyl carboxylase activity. The remaining two SNPs (2 and 5) are located within non-coding intron sequences. These 4 SNPs allowed for determining the genotype associated with the observed fatal coagulopathy. Screening for the premature truncation (SNP-4) based on the presence of a Bbv I restriction site in clinically normal lambs but not in the homozygous affected lambs allows for detection of the heterozygous state (GATT/GACC), because carrier animals are clinically normal.     

Association of neonatal serum immunoglobulin G1 concentration with health and performance in beef calves

OBJECTIVE: To evaluate associations between neonatal serum IgG1 concentration and pre- and postweaning morbidity and mortality rates and average daily gains (ADGs) in beef calves and define a cutoff point for serum IgG1 concentration necessary for optimal health and performance of beef calves. DESIGN: Nonconcurrent cohort study. ANIMALS: 1,568 crossbred beef calves. PROCEDURE: Single radial immunodiffusion was used to quantitate IgG1 concentration in sera collected from calves between 24 and 72 hours after birth. Logistic regression, ANCOVA, and likelihood ratios were used to analyze data. RESULTS: In the preweaning period, lower perinatal IgG1 concentrations were significantly associated with higher morbidity rates, higher mortality rates, and lower ADGs. Calves with serum IgG1 concentration < 2,400 mg/dL were 1.6 times as likely to become ill before weaning and 2.7 times as likely to die before weaning as calves with higher serum IgG1 concentrations. Calves with serum IgG1 concentration of at least 2,700 mg/dL weighed an estimated 3.35 kg (7.38 lb) more at 205 days of age than calves with lower serum IgG1 concentration. No significant association of serum IgG1 concentration with feedlot morbidity, death, or ADG was identified. CONCLUSIONS AND CLINICAL RELEVANCE: By use of likelihood ratios, the threshold of serum IgG1 concentration for optimal health and performance of calves was higher than values reported previously. Implementation and maintenance of management and intervention strategies designed for early detection and treatment of calves at risk for failure of passive transfer will likely result in increases in preweaning health and performance parameters.     

Small ruminant lentivirus genetic subgroups associate with sheep TMEM154 genotypes

Small ruminant lentiviruses (SRLVs) are prevalent in North American sheep and a major cause of production losses for the U.S. sheep industry. Sheep susceptibility to SRLV infection is influenced by genetic variation within the ovine transmembrane 154 gene (TMEM154). Animals with either of two distinct TMEM154 haplotypes that both encode glutamate at position 35 of the protein (E35) are at greater risk of SRLV infection than those homozygous with a lysine (K35) haplotype. Prior to this study, it was unknown if TMEM154 associations with infection are influenced by SRLV genetic subgroups. Accordingly, our goals were to characterize SRLVs naturally infecting sheep from a diverse U.S. Midwestern flock and test them for associations with TMEM154 E35K genotypes. Two regions of the SRLV genome were targeted for proviral amplification, cloning, sequence analysis, and association testing with TMEM154 E35K genotypes: gag and the transmembrane region of env. Independent analyses of gag and env sequences showed that they clustered in two subgroups (1 and 2), they were distinct from SRLV subtypes originating from Europe, and that subgroup 1 associated with hemizygous and homozygous TMEM154 K35 genotypes and subgroup 2 with hemi- and homozygous E35 genotypes (gag p < 0.001, env p = 0.01). These results indicate that SRLVs in the U.S. have adapted to infect sheep with specific TMEM154 E35K genotypes. Consequently, both host and SRLV genotypes affect the relative risk of SRLV infection in sheep.     

Diagnosis of African horsesickness

African horsesickness (AHS) is a very serious, non-contagious disease of horses and other solipeds caused by an arthropod-borne orbivirus of the family Reoviridae. The epizootic nature of the disease makes rapid, accurate diagnosis of AHS absolutely essential. Currently, diagnosis of AHS is based on typical clinical signs and lesions, a history consistent with vector transmission and confirmation by laboratory detection of virus and/or anti-AHS virus antibodies. The clinicopathologic presentation of AHS, current and next generation laboratory diagnostic methods are discussed.     

Acute hemolytic anemia after oral administration of L-tryptophan in ponies

The hematologic and pathologic effects of orally administered L-tryptophan and indoleactic acid and of L-tryptophan administered IV were studied in ponies. Sixteen adult Shetland ponies were allotted into 4 experimental groups. Group 1 consisted of 5 ponies (1-5) given 0.6 g of tryptophan/kg of body weight in a water slurry via stomach tube. Group 2 included 4 ponies (6-9) given 0.35 g of tryptophan/kg orally. Group-3 ponies (10-13) were given 0.35 g of indoleacetic acid/kg orally. Group 4 consisted of 3 ponies (14-16) given a single 4-hour IV infusion of 0.1 g of tryptophan/kg. Restlessness, increased respiratory rate, hemolysis, and hemoglobinuria were detected in 4 of the 5 group-1 ponies. Only pony 7 in group 2 developed hemolysis, hemoglobinuria, and a significant increase in respiratory rate. Renal pathologic lesions, consistent with hemoglobinuric nephrosis, were seen in ponies 2, 4, 5, and 7. Bronchiolar degeneration was evident in 4 of 9 ponies given tryptophan orally. The importance of these respiratory lesions was unknown. Clinical or pathologic abnormalities were not noticed in the ponies of groups 3 and 4. Mean plasma tryptophan values increased significantly in groups 1 and 2 at 6 hours after dosing. A second peak of tryptophan was detected in both groups at 12 hours. Values returned to predose values by 48 hours. Plasma indole and 3-methylindole concentrations were detectable in only 2 ponies (4 and 7). In vitro incubations of cecal fluid from ponies 6, 8, and 9 yielded a percentage conversion of tryptophan to indole of 16.75%, 5.84%, and 7.96%, respectively. 3-Methylindole was not produced. These results suggested that indole was the major metabolite of orally administered tryptophan in these ponies.