Microbiologic and Pathologic Findings in an Epidemic of Equine Pericarditis

During the spring and summer of 2001 and in association with the mare reproductive loss syndrome, 22 terminal and 12 clinical cases of equine pericarditis were diagnosed in central Kentucky. Actinobacillus species were the principal isolates from 8 of 10 nontreated, terminally affected and 3 of 10 clinically affected horses. Enterococcus faecalis and Streptococcus zooepidemicus were cultured from the remaining 2 nontreated terminal cases. No viruses were isolated in tissue culture. Nucleic acid of equine herpesvirus-2 was detected in pericardial and tracheal wash fluids of 3 and 1 individuals, respectively. Microscopic alterations in sections of heart and parietal pericardium were consistent with chronic fibrinous bacterial pericarditis. This report confirms a significant role of Actinobacillus species in equine pericarditis and describes an epidemic of this infrequently observed syndrome in the horse.

Thermotaxis of Dictyostelium discoideum amoebae and its possible role in pseudoplasmodial thermotaxis

Thermotaxis by individual amoebae of Dictyostelium discoideum on a temperature gradient is described. These amoebae show positive thermotaxis at temperatures between 14 degrees C and 28 degrees C shortly (3 hr) after food depletion. Increasing time on the gradient reduces the positive thermotactic response at the lower temperature gradients (midpoint temperatures of 14, 16, and 18 degrees C), and amoebae show an apparent negative thermotactic response after 12 hr on the gradient. The thermotaxis response curve for "wild-type" amoebae after 16 hr on the gradient is similar to that shown for the pseudoplasmodia. Growth of the amoebae at a different temperature causes a shift in the thermotaxis response curve for the amoebae. This adaptation is similar to that shown for the pseudoplasmodia. Two mutants in thermotaxis, HO428 and HO813, show changes in amoebal thermotaxis similar to the observed changes in pseudoplasmodial thermotaxis. On the basis of the similarities between these responses, thermotaxis by the amoebae is proposed to be the basis for thermotaxis by the multicellular pseudoplasmodium.

Prevalence of latent, neuropathogenic equine herpesvirus-1 in the Thoroughbred broodmare population of central Kentucky

REASON FOR PERFORMING STUDY

An emerging problem of equine herpesvirus-1 (EHV-1) infection in horses in the USA is a high-mortality myeloencephalopathy that commonly occurs where large numbers of horses are stabled. EHV-1 isolates recovered from recent neurological outbreaks represent a mutant virus strain that possesses enhanced neuropathogenicity. A central question of EHV-1 myeloencephalopathy is the latency carriage rate for these mutants of EHV-1 in USA horse populations.

OBJECTIVE

To estimate the prevalence of neuropathogenic strains of EHV-1 as latent infections in the Thoroughbred broodmare population of central Kentucky.

METHODS

Submandibular lymph nodes (SMLN) were collected during post mortem examination of 132 Thoroughbred broodmares. Total DNA purified from SMLN tissue was tested for the presence of latent EHV-1 DNA by an ultrasensitive magnetic bead-based, sequence-capture, nested PCR method. Differentiation of active from latent infections by EHV-1 was achieved by detection of transcripts of EHV-1 glycoprotein B by reverse transcription PCR.

RESULTS

Latent EHV-1 DNA was detected in the SMLN tissues of 71 (54%) of the 132 mares submitted for necropsy. Thirteen (18%) of the 71 latently infected horses harboured the neuropathogenic biovar of EHV-1. Of the 13 horses latently infected with an ORF30 mutant strain of EHV-1, 11 also carried a latent, wild-type strain of the virus in their SMLN tissues.

CONCLUSIONS

Neuropathogenic strains of EHV-1 have established a significant presence in the Thoroughbred broodmare population of central Kentucky as latently infected carrier horses. The data also indicate that a highly sensitive DNA detection method is required to identify many instances of EHV-1 latency.

POTENTIAL RELEVANCE

The presence of a relatively large biological reservoir of latent, neuropathogenic EHV-1 has the potential for posing emerging equine health and economic threats to the future prosperity of the USA horse industry.

Three equine cases of mixed hepatoblastoma with teratoid features

Hepatoblastoma was diagnosed in 3 Thoroughbreds at the University of Kentucky Livestock Disease Diagnostic Center (LDDC) since 1997. Case #1 involved a fetus with a well-demarcated, multilobulated, solitary mass that extended from the left liver lobe. Case #2 was observed in a neonate with a primary hepatic mass and multiple metastases in the skin, brain, meninges, and stylohyoid bone. Case #3 was a solitary hepatic mass incidentally discovered in a neonate at necropsy. Microscopically, the masses were similarly composed of sheets and cords of fetal and embryonal epithelial cells that frequently formed sinusoid-like structures. Intermixed with the neoplastic epithelial cells were variable amounts of hemorrhage, necrosis, osteoid, and bone. Immunohistochemically, the epithelial cells stained variably positive for alpha- fetoprotein, frequently positive for vimentin, and occasionally positive for cytokeratin. All 3 cases were diagnosed as mixed hepatoblastoma with teratoid features.

Dietary vitamin E and selenium and toxicity of nitrite and nitrate

Nitrites and nitrates are important antimicrobial and flavoring/coloring agents in meat and fish products. However, nitrites and nitrates may cause methemoglobinemia and other illness, and may react with certain amines to form carcinogenic nitrosamines. The nutritional status of vitamin E and selenium has long been associated with nitrite and nitrate toxicity, although the mechanism involved is not yet clear. Information available recently shows that nitrites and nitrates are both oxidation products and ready sources of nitric oxide (NO*), that NO* reacts rapidly with superoxide to form highly reactive peroxynitrite (ONOO-), and that vitamin E may mediate the generation and availability of superoxide and NO*. Increased formation of ONOO- resulting from nitrite treatment and low intake of vitamin E and selenium may thus be the critical event leading to tissue damage and animal mortality observed previously. The protection against the adverse effects of nitrites/nitrates by vitamin E is attributed to its ability to reduce ONOO- formation, while selenium exerts its protective effects via seleno-enzymes/compounds, which reduce ONOO- formed.

Expression of the seqA gene is negatively modulated by the HU protein in Escherichia coli

The SeqA protein acts as a regulator of chromosomal replication initiation in Escherichia coli by sequestering hemi-methylated oriC, effectively blocking methylation and therefore preventing rapid re-initiation. The level of SeqA protein is maximal at mid-log phase and decreases when cells enter late-log phase. In hup mutants that lack the HU protein, the maximal seqA expression is also seen at mid-log phase, but seqA expression, as well as SeqA levels and activity, is increased by up to four fold relative to that in the wild type. These results suggest that the HU protein functions as a negative modulator of seqA expression.

Relationships between acute sediment toxicity in laboratory tests and abundance and diversity of benthic infauna in marine sediments: a review

Acute sediment toxicity tests have become important in regulatory, monitoring, and scientific programs, partly because it has been assumed that they are indicative of ecological damage to benthic infaunal resources. Data from tests of sediment toxicity and measures of benthic community structure were examined from > 1,400 saltwater samples to determine the relationships between acute toxicity and changes in the abundance and diversity of infauna resources. Data were compiled from studies conducted along portions of the Atlantic, Gulf of Mexico, and Pacific coasts of the United States. There was considerable variability among the data sets in the relationships between laboratory results and benthic measures. However, in 92% of the samples classified as toxic, at least one measure of benthic diversity or abundance was < 50% of the average reference value. In 67% of these samples, at least one measure of benthic infauna abundance or diversity was < 10% of average reference conditions. No amphipods were found in 39% of samples that were classified as toxic, whereas amphipods were absent from 28% of the nontoxic samples. In many survey areas, the abundance of crustaceans (notably the amphipods) decreased in the infauna as amphipod survival decreased in the laboratory tests. There appeared to be a break point in the data indicating that, generally, amphipod abundance in the field was lowest when survival in the laboratory tests dropped below 50% of controls. Based on the weight of evidence from all the data analyses, we conclude that ecologically relevant losses in the abundance and diversity of the benthic infauna frequently corresponded with reduced amphipod survival in the laboratory tests.

Intoxication of sheep exposed to ozark milkweed (Asclepias viridis Walter)

Some 20 sheep died 1 at a time on a farm in Fleming County, KY, in late July of 1999 after consumption of Asclepias viridis Walter. Major histological lesions were mild multifocal nonsuppurative myocarditis. Gross pathology revealed wet and heavy lungs. Many affected animals had a hunched appearance, and marked posterior paresis was also observed.

High temperature stress resistance of Escherichia coli induced by a tobacco class I low molecular weight heat-shock protein

TLHS1 is a class I low molecular weight heat-shock protein (LMW HSP) of tobacco (Nicotiana tabacum). For a functional study of TLHS1, a recombinant DNA coding for TLHS1 with a hexahistidine tag at the amino-terminus was constructed and expressed in Escherichia coli. An expressed fusion protein, H6TLHS1, was purified using a Ni2+ affinity column and a Sephacryl S400 HR column. A polyclonal antibody against H6TLHS1 was produced to follow the fate of H6TLHS1 in E. coli. The fusion protein in E. coli maintained its solubility at a temperature of up to 90 degrees C and most of the proteins in the E. coli cell lysate with H6TLHS1 were prevented from thermally induced aggregation at up to 90 degrees C. We compared the viability of E. coli cells expressing H6TLHS1 to the E. coli cells without H6TLHS1 at a temperature of 50 degrees C. After 8 h of high temperature treatment, E. coli cells with H6TLHS1 survived about three thousand times more than the bacterial cells without H6TLHS1. These results showed that a plant class I LMW HSP, TLHS1, can protect proteins of E. coli from heat denaturation, which could lead to a higher survival rate of the bacterial cells at high temperature.

Glomerular lesions in male rabbits treated with aluminium lactate: with special reference to microaneurysm formation

Novel glomerular lesions were seen in male rabbits after intravenous administration of aluminum lactate. Eight rabbits in the treated group were given 0.1 mmol/kg of aluminum lactate 5 days a week for 4 weeks. The control group of 8 rabbits was given 0.3 mmol/kg of sodium lactate by the same injection protocol. In the treated group, the mesangial cells in the glomerular tufts in 6 of 8 rabbits were distended with grayish blue granular material, which was identified by laser microprobe mass spectrometry and acid solochrome azurine stain as an aluminum compound. Other consistent findings in the glomeruli included microaneurysm in 6 of 8 rabbits and segmental sclerosis in 6 of 8 rabbits. Less frequently observed glomerular changes included crescent formation, necrosis with calcification, fibrosis of the Bowman's capsule, cystic dilation of the Bowman's space, and exudation of erythrocytes into the Bowman's space. The mechanism by which aluminum lactate induces the glomerular changes is not certain. However, the pathogenesis may involve the deposition of aluminum in the mesangial cells, resulting in mesangiolysis which in turn causes microaneurysm. The sclerotic change is interpreted as a sequela of microaneurysm. The findings suggest that aluminum induces glomerular lesions in rabbits. This may serve as a good animal model to study mesangiolysis and microaneurysm formation.

Malignant rhabdoid tumour in the orbit of a horse

A malignant rhabdoid tumour was diagnosed in the orbit of a 2-year-old Thoroughbred filly. The neoplasm, which was very aggressive, was present in nearly every part of the ocular and periocular structures and had spread to the lymph nodes of the head and neck, the salivary glands and the subcutaneous tissues around the eye. The neoplasm was composed of polygonal cells with abundant eosinophilic cytoplasm. Many cells had a large, vesiculate, indented nucleus and contained a paranuclear globular inclusion. Ultrastructurally, the inclusions were seen to consist of whorls of intermediate filaments. The neoplastic cells were immunoreactive to vimentin and cytokeratin antisera, but were negative for desmin and actin.

Comparison of the structure and expression pattern for a low molecular weight heat-shock protein cDNA clone from Nicotiana tabacum

We isolated a cDNA clone, named TLHS-1, for a low molecular weight heat-shock protein (LMW HSP) from tobacco. The nucleotide sequence determination of the clone identified an open reading frame for 159 amino acids. To the upstream of the open reading frame, a sequence of 124 nucleotides was determined. To the 3' downstream of the open reading frame, 212 nucleotides were identified which carried a poly(A) tail. A comparison of the open reading frame of TLHS-1 with the previously reported class I LMW HSPs showed a high identity which classified the TLHS-1 as a class I LMW HSP cDNA clone. Reexamination of the amino acid sequences for LMW HSPs including the TLHS-1 argued for the necessity to redraw the consensus region. Six consensus regions were proposed instead of the two consensus regions suggested previously. A RNA blot hybridization for TLHS-1 showed the typical expression pattern of a heat-shock inducible gene from 3 common tobacco cultivars. The genomic DNA blot hybridization for the TLHS-1 gene from the 3 tobacco cultivars showed identical patterns. These results implied that the expression control and structure of the TLHS-1 gene have been well conserved in the tobacco cultivars which are not bred for high temperature stress resistance.

Structure of a polyubiquitin gene in Nicotiana tabacum

Using a tobacco ubiquitin cDNA clone as a probe, a genomic clone in EMBL3 coding for a tobacco polyubiquitin protein was isolated. Southern blot hybridization of the genomic clone with the cDNA clone identified a BamHI/EcoRI fragment of 2.5 kb to contain the coding region of polyubiquitin, and thus the fragment was subcloned into a plasmid vector. Nucleotide sequence determination of the clone identified an open reading frame for the four head-to-tail repeats of ubiquitin monomer of 76 amino acids interrupted by an intron sequence of 55 nucleotides. The four ubiquitin units were completely conserved except for the extra glutamine at the carboxy terminus of the last ubiquitin monomer. At the 5'-region upstream of the open reading frame, a sequence of 630 nucleotides was determined. In this region, well-known regulatory sequences such as the CCAAT box, TATA box and heat-shock elements could not be located; instead, a region very rich in C and T and repeats of CA was noticed. In the 3'-downstream region of the open reading frame, a sequence of 474 nucleotides was determined which contained putative polyadenylation signals and a GU-rich region.

Antiapoptotic compound to enhance hypothermic liver preservation

BACKGROUND

Apoptosis (programmed cell death) occurs as a consequence of global organ ischemia during isolation and storage prior to transplantation. If apoptosis is inhibited during ischemia, organ preservation should be improved, and the length of time for permissible storage may be increased. The objective of this study was to test the effect of a newly developed antiapoptotic compound, LXR-015, during extended hypothermic liver preservation.

METHODS

Three groups of 12 rats each were studied. In the normal group, liver function was studied immediately after harvesting. In the study group, harvested livers were flushed with Euro-Collins solution (30 ml/kg body weight) containing LXR-015 at a concentration equivalent to 9 mg/kg animal body weight (300 microg/ml). The livers were then stored at 4 degrees C for 24 hr before liver function was studied. In the control group, harvested livers were flushed with Euro-Collins solution without LXR-015 and then stored at 4 degrees C for 24 hr before liver function was studied.

RESULTS

Portal venous flow was higher (P<0.05) in the normal and study groups compared with the control group. Portal venous resistance was lower (P<0.05) in the normal and study groups compared with the control group. Liver tissue oxygen consumption in the study group was significantly higher than in both the normal and control groups (P<0.05). Liver enzyme production (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatine kinase) was higher in the control group than in either the study or normal group (P<0.05). Bile production in both the normal and study groups was higher than in the control group (P<0.05). The liver tissue wet to dry weight ratio in both the normal and study groups was lower than in the control group (P<0.05). Histopathology studies revealed fewer apoptotic bodies (P<0.05) in both the normal (1.70+/-0.15 per high-power field) and study groups (2.08+/-0.10 per high-power field) than in the control group (7.92+/-.33 per high-power field).

CONCLUSIONS

Adding an antiapoptotic compound, LXR-015, to Euro-Collins solution significantly improves hypothermic preservation of the rat liver compared with Euro-Collins solution alone.

Nucleotide sequence of a ubiquitin-extension protein gene in Nicotiana tabacum and its expression pattern upon heat shock

Using a tobacco cDNA clone as a probe, a genomic clone coding for a tobacco ubiquitin extension protein was isolated. Nucleotide sequence determination of the clone identified an open reading frame for an ubiquitin unit of 76 amino acids and an extension tail of 80 amino acids. To the 5' upstream of the open reading frame, a sequence of 1,110 nucleotides was determined and a putative CCAAT box and TATA box were located. An intron sequence was not apparent as the open reading frame for the ubiquitin-extension protein was continuous for 468 nucleotides. In the 3' downstream region of the gene, a putative polyadenylation signal and GU rich region were observed. Northern blot analysis of tobacco transcripts with the tail part of the gene as a probe specifically identified the 1.3 kb transcript. The Northern signal at 1.3 kb indicated that the expression of the ubiquitin-extension protein gene in tobacco is downregulated upon heat-shock.

Short-term oral 3-hydroxypyridin-4-one dosing increases aluminum excretion and partially reverses aluminum-induced toxicity in the rabbit independent of chelator lipophilicity

The objectives of the present study were to determine the efficacy and toxicity of repeated oral administration of 3-hydroxypyridin-4-one (HP) chelators in a rabbit model of aluminum (Al) accumulation and toxicity, and the influence of chelator lipophilicity on these effects. Efficacy was assessed as chelator-induced Al mobilization and excretion and reversal of Al accumulation and Al-induced toxicity. Chelator-induced toxicity was assessed by multiple measures. Six HPs were given orally 12 times over 1 month to Al-loaded rabbits, which had significant elevation of Al in most tissues and evidence of Al-induced nephrotoxicity, osteomalacia, and anemia. Intravenous desferrioxamine (DFO), the current chelator of choice for the treatment of Al-overload and toxicity, was included as a positive control. All six HPs and DFO demonstrated efficacy evidenced by significantly greater urinary and biliary Al elimination after the twelfth dose than seen in saline-treated controls. All of the HPs were more effective than DFO. Chelator-induced urinary Al excretion accounted for 58-98% of total (urinary plus biliary) Al excretion. Chelator-facilitated Al excretion was nearly complete within 12 hr, demonstrating a fairly short duration of action in rabbits with intact renal function. HP treatments did not consistently affect tissue concentrations of Al or other metals. However, there was a trend toward chelator-induced reduction of Al-induced nephrotoxicity. The influence of HP lipophilicity was limited to a positive correlation between HP x Al lipophilicity and biliary Al output and a negative correlation between HP and HP x Al lipophilicity and reduction of Kupffer cell Al. Little toxicity was evident after repeated oral HP dosing. Adrenal weight increased after treatment with several HPs. There was a decrease in testes weight after several HPs, which is consistent with an antiproliferative effect. More frequent dosing and/or a longer duration of HP treatment might produce greater reversal of the Al-induced toxicity and perhaps reveal more adverse effects than seen in this study. There was a lack of profound toxicity during this short-term study. The 1,2-dimethyl (CP20) and 1,2-diethyl (CP94) HPs, which have been the most extensively studied HPs, were the least effective of the HPs examined. These results encourage the further investigation of other HPs as oral alternatives to DFO for the treatment of Al accumulation and toxicity.

Experimental asthma developed by room air contamination with cockroach allergen

To study the asthmatogenic effect of certain airborne elements of the home environment, we studied a group of guinea pigs exposed to aerosolized cockroach allergen (CRa) and side-stream cigarette (S-SC) smoke. Four groups of guinea pigs were exposed to aerosols, either saline or CRa, for 4 weeks, after a sham or S-SC smoke pretreatment. Anaphylactic antibodies were measured by passive cutaneous anaphylaxis (PCA) assay and by skin test. Animals were challenged with aerosol CRa on day 35, and lung function and leukotrienes (LTB4 and LTC4/D4) were measured. Skin tests were positive on days 21 and 29. The antibodies were heat-stable, IgG1a-like antibodies (PCA titers 1:2-18). The CRa challenge caused an immediate reduction in both the maximal expiratory flow rate at 50% of the lung capacity and respiratory compliance. The decreased lung function continued for up to 6 h (p < 0.0001). LTB4 and LTC4/D4 were elevated (p < 0.0001) in the sensitized animals at the corresponding times of reduced lung function. S-SC smoke did not affect the CRa sensitization; instead, a protective effect on the CRa-induced bronchospasms was noted. Thus, the study indicates that a simple airborne CRa exposure without an adjuvant sensitizes guinea pigs, and that the animals respond to antigen challenge with CRa-specific airway obstructions.

Congenital polyalveolar lobe in three foals

Three cases of congenital polyalveolar lobe (pulmonary hamartoma) were diagnosed in female Thoroughbred foals. Foal 1 was born at full term but died shortly afterwards. Foal 2 was aborted at the seventh month of gestation. Parturition was induced at the tenth month of gestation in foal 3 because it developed hydrops of the amnion and ascites. In all three foals, the polyalveolar lobe occurred on the right side and affected the entire right lung. In each case, the right lung formed a tumour-like mass, and expanded into the left chest cavity. The lung masses were pink to dark red and spongy to rubbery, with marked lobular patterns on the pleural and cut surfaces. The left lung was compressed and small. The right and left lungs weighed 0.9-6.3 kg and 80 g-0.3 kg, respectively. Microscopically, the polyalveolar lobe consisted of normal alveoli, bronchioli and blood vessels, but the alveolus:artery ratio was greater than normal. In the polyalveolar lobe of two foals the numbers of alveoli per artery were 65.2 and 52.5; in contrast, the corresponding values for three control lungs were 26.9, 26.5 and 27.6. Chronic passive congestion with generalized oedema was observed in foals 2 and 3.

Influenza virus infections in Taiwan from 1979 to 1995

In order to understand the epidemic trends of influenza virus infection in Taiwan, 5,882 throat-swab specimens were collected from June 1979 to June 1995. Influenza virus was detected in 313 specimens including samples collected at Taichung and Tainan from 1981 to 1982. Among them, 214 isolates (68.4%) were identified as influenza virus type A, and 99 (31.6%) as type B. In the course of the surveillance, the influenza virus strain A/Taiwan 1/86 (H1N1), known as a world-wide reference strain, was isolated in April 1986. Influenza virus infection was identified throughout the year in Taiwan based on the frequency of detection of the virus. Some strains were referred to as intermediate strains in comparison with the reference strains on the basis of antigenic heterogeneity. About 80% of the isolates identified in this laboratory were from children under 12 years old. The rate of isolation of virus was about 46% during the epidemic season.

Rhodococcus equi-associated necrotizing lymphadenitis in a llama

A case of Rhodococcus equi-associated necrotizing lymphadenitis in a 2-year-old male llama is described. Caseous necrosis, resembling macroscopically that seen in ovine caseous lymphadenitis, was observed diffusely in the tracheobronchial and mediastinal lymph nodes, and in an extensive lesion in the lungs. Necrosis was present to a lesser extent in the spleen and hepatic and gastric lymph nodes. Numerous bacteria-laden macrophages were present around the necrotic areas. The findings suggest that, as in cattle and pigs, the primary targets of R. equi infection in the llama are the lymphoid organs.

Causes of abortion, stillbirth, and perinatal death in horses: 3,527 cases (1986-1991)

Pathology case records of 3,514 aborted fetuses, stillborn foals, or foals that died < 24 hours after birth and of 13 placentas from mares whose foals were weak or unthrifty at birth were reviewed to determine the cause of abortion, death, or illness. Fetoplacental infection caused by bacteria (n = 628), equine herpesvirus (143), fungi (61), or placentitis (351), in which an etiologic agent could not be defined, was the most common diagnosis. Complications of birth, including neonatal asphyxia, dystocia, or trauma, were the second most common cause of mortality and were diagnosed in 19% of the cases (679). Other common diagnoses were placental edema or premature separation of placenta (249), development of twins (221), contracted foal syndrome (188), other congenital anomalies (160), and umbilical cord abnormalities (121). Less common conditions were placental villous atrophy or body pregnancy (81), fetal diarrhea syndrome (34), and neoplasms or miscellaneous conditions (26). A diagnosis was not established in 16% of the cases seen (585). The study revealed that leptospirosis (78) was an important cause of bacterial abortion in mares, and that infection by a nocardioform actinomycete (45) was an important cause of chronic placentitis.

Equine abortion and stillbirth in central Kentucky during 1988 and 1989 foaling seasons

Pathologic and microbiologic examinations were performed on 1,211 aborted equine fetuses, stillborn foals, and placentas from premature foals in central Kentucky during the 1988 and 1989 foaling seasons to determine the causes of reproductive loss in the mare. Placentitis (19.4%) and dystocia-perinatal asphyxia (19.5%) were the 2 most important causes of equine reproductive loss. The other causes (in decreasing order) were contracted foal syndrome and other congenital anomalies (8.5%), twinning (6.1%), improper separation of placenta (4.7%), torsion of umbilical cord (4.5%), placental edema (4.3%), equine herpesvirus abortion (3.3%), bacteremia (3.2%), fetal diarrhea (2.7%), other placental disorders (total of 6.0%), and miscellaneous causes (1.6%). A definitive diagnosis was not established in 16.9% of the cases submitted. Streptococcus zooepidemicus, Escherichia coli, Leptospira spp., and a nocardioform actinomycete were organisms most frequently associated with bacterial placentitis, and Aspergillus spp. was the fungus most often noted in mycotic placentitis. No viral placentitis was noticed in this series. Dystocia-perinatal asphyxia was mostly associated with large foals, maiden mares, unattended deliveries, and malpresentations. The results of this study indicate that in central Kentucky, the noninfectious causes of equine reproductive loss outnumber the infectious causes by an approximate ratio of 2:1, placental disorders are slightly more prevalent than nonplacental disorders, Leptospira spp. and a nocardioform actinomycete are 2 new important abortifacient bacteria in the mare, the occurrence of contracted foal syndrome is unusually frequent, the incidence of twin abortion has sharply declined, and torsion of the umbilical cord is an important cause of abortion in the mare.

Leptospirosis in equine fetuses, stillborn foals, and placentas

Leptospirosis was diagnosed in 51 equine fetuses and 16 stillborn foals with gestational ages from 3 1/2 to 11 months. Diagnosis was based on one or more of the following: positive fetal antibody titer, positive fluorescent antibody test, demonstration of spirochetes in kidney and/or placental sections stained by the Warthin-Starry technique, high leptospiral titers in aborting mares, or isolation of Leptospira spp. from fetal organs. Gross lesions were observed in 80.3% of the fetuses, stillborn foals, and placentas. Gross placental lesions included nodular cystic allantoic masses, edema, areas of necrosis of the chorion, and necrotic mucoid exudate coating the chorion. The liver (23 cases) was enlarged, mottled, and pale to yellow. The kidneys (seven cases) were swollen and edematous with pale white radiating streaks in cortex and medulla. Microscopic lesions were observed in 96% of fetuses, stillborn foals, and placentas. Placental lesions consisted of thrombosis, vasculitis, mixed inflammatory cell infiltration of the stroma and villi, cystic adenomatous hyperplasia of allantoic epithelium, and villous necrosis and calcification. Fetal lesions included hepatocellular dissociation, mixed leukocytic infiltration of the portal triads, giant cell hepatopathy, suppurative and nonsuppurative nephritis, pulmonary hemorrhages, pneumonia, and myocarditis. Spirochetes were demonstrated with the Warthin-Starry stain in the allantochorion and/or kidney of 69 of the 71 cases. Using the direct fluorescent antibody technique, 56/60 cases tested positively for leptospires. Leptospires were isolated from fetal tissues in 20/42 cases. Sixteen of the isolates were identified by restriction enzyme analysis as Leptospira interrogans serogroup Pomona serovar kennewicki; case Nos. 36 and 41 were serovar grippotyphosa.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenomatous hyperplasia of equine allantoic epithelium

Adenomatous hyperplasia with or without cystic formation of allantoic epithelium was observed in 63/954 equine placentas examined from 1 February 1988 to 31 January 1990. In 61/63 placentas, the adenomatous hyperplasia was associated with other placental lesions: 49 with chronic or chronic-active placentitis, six with placental edema, three with fetal diarrhea, one with placentitis and fetal diarrhea, one with fetal diarrhea and placental edema, and one with hyperplasia of chorionic epithelium. When lesions were less severe, the hyperplastic lesions were not grossly visible, but when lesions were severe, nodular, tumorous, cystic masses were observed at or near the insertion site of umbilical blood vessels. Histologically, lesions classified as stage 1 were characterized by hypertrophy and hyperplasia of epithelial cells and formation of intraepithelial glands (lumina). Lesions classified as stage 2 were characterized by the presence of fibro-adenomatous changes in the allantoic stroma. Lesions classified as stage 3 were characterized by the formation of the nodular masses, which were composed of glandular or cystic structures of various sizes lined by cuboidal or low to medium columnar epithelium. These glands or cysts were empty or contained amphophilic secretion, a mixture of neutrophils and secretion material, or neutrophils. The cause of adenomatous hyperplasia of the equine allantois is not certain; however, there is a close connection between chronic placental disorders and this hyperplastic lesion.

Etiology and pathology of equine placentitis

Placentas from aborted, stillborn, and premature foals were examined during the 1988 and 1989 foaling seasons, and 236 of 954 (24.7%) had placentitis. Microorganisms associated with placentitis were isolated or demonstrated from 162 of 236 (68.6%) placentitis cases. Leptospira spp. and a nocardioform actinomycete were 2 important, newly emerging bacteria associated with equine placentitis. Major pathogens identified in decreasing order were Streptococcus zooepidemicus, Leptospira spp., Escherichia coli, a nocardioform actinomycete, fungi, Pseudomonas aeruginosa, Streptococcus equisimilis, Enterobacter agglomerans, Klebsiella pneumoniae, and alpha-hemolytic Streptococcus. Pathogens were not recovered in 64 cases (27.1%) and overgrowth by saprophytic bacteria was recorded in 10 cases (4.2%). Twenty-seven cases (16.6%) had mixed bacterial growth and 93 cases (57.4%) had bacteria cultured from both placenta and fetal organs. The majority of the placentitis cases caused by bacteria, with the exception of Leptospira spp. and the nocardioform actinomycete, occurred in 2 forms. One was acute, focal or diffuse; had an infiltration of neutrophils in the intervillous spaces or necrosis of chorionic villi; was associated with bacteremia; and frequently occurred in the placenta from fetuses expelled before or at midgestation. The other was observed from foals expelled at late gestation, was mostly chronic and focal or focally extensive, and occurred mostly at the cervical star area. Chronic placentitis was characterized by the presence of 1 or a combination of the following lesions: necrosis of chorionic villi, presence of eosinophilic amorphous material on the chorion, and infiltration of mononuclear inflammatory cells in the intervillous spaces, villous stroma, chorionic stroma, vascular layer, and allantois.(ABSTRACT TRUNCATED AT 250 WORDS)

Brucella abortus-associated meningitis in aborted bovine fetuses

Granulomatous meningitis was present in 6/33 bovine fetuses from which Brucella abortus (B. abortus) had been isolated. Meningitis was severe in three fetuses, moderate in one fetus, and mild in the remaining two fetuses. The meningitis was characterized by the infiltration of a mixed population of lymphocytes, plasma cells, and macrophages in the leptomeninges. Vasculitis characterized by the infiltration of lymphocytes and plasma cells in the vascular wall was observed in the vessels of the cerebral cortices of 4/6 fetuses. Gram negative coccobacilli were present in the cytoplasm of the leptomeningeal macrophages and extracellularly. Brucellar antigens labeled by the avidin-biotin-peroxidase complex method were present in massive amounts in leptomeningeal macrophages and in small foci of stained cells in the choroid plexus and ependyma. The findings indicate that B. abortus is one of pathogens capable of inducing meningitis in bovine fetuses.

A prespore gene, Dd31, expressed during culmination of Dictyostelium discoideum

During culmination of Dictyostelium fruiting bodies, prespore and prestalk cells undergo terminal differentiation to form spores and a cellular stalk. A genomic fragment was isolated by random cloning that hybridizes to a 1.4-kb mRNA present during culmination. Cell type separations at culmination showed that the mRNA is present in prespore cells and spores, but not in prestalk or stalk cells. After genomic mapping, an additional 3 kb of DNA surrounding the original 1-kb fragment was cloned. The gene was sequenced and named Dd31 after the size of the predicted protein product in kilodaltons. Accumulation of Dd31 mRNA occurs immediately prior to sporulation. Addition of 20 mM 8-Br-cAMP to cells dissociated from Mexican hat stage culminants induced sporulation and the accumulation of Dd31 mRNA, while 20 mM cAMP did not. Dd31 mRNA does not accumulate in the homeotic mutant stalky in which prespore cells are converted to stalk cells rather than spores. Characterization of Dd31 extends the known temporal dependent sequence of molecular differentiations to sporulation.

Campylobacteriosis in an aborted equine fetus

Abortion caused by Campylobacter fetus subsp fetus was diagnosed in a 7-month-old equine fetus. The fetus was small for its gestational age. Macroscopically, the proximal portion of the small intestine was hemorrhagic and its wall was thick. Histologically, the Brunner glands were distended with neutrophils, and the submucosa was thick, owing to fluid accumulation and/or cellular infiltrates. Curved bacteria were observed in the Brunner glands and intestinal glands. Campylobacter fetus subsp fetus was isolated from stomach contents, liver, and lungs, and was detected by dark-field microscopic examination of ocular fluid and stomach contents. Placenta was not available for examination.

Regulation of SP60 mRNA during development of Dictyostelium discoideum

The accumulation of mRNA recognized by oligonucleotides coding for a portion of the spore coat protein, SP60, was determined throughout development of Dictyostelium discoideum. The 1.8 kb mRNA first appears at the tipped aggregate stage and accumulates until culmination. This mRNA is present in pre-spore cells but absent from pre-stalk cells. A cDNA clone was selected by the oligonucleotides and found to be homologous to this mRNA. Although the oligonucleotides were designed to match the sequence coding for a hexapeptide repeat at the amino-terminus of SP60, they were able to recognize a similar repeated region at the carboxy-terminus of the protein coded by the cDNA clone. The SP60 gene appears to be subject to temporal and cell-type-specific transcriptional controls that are coordinate with those of SP96, another spore coat gene.

Induction of eosinophilic enteritis and eosinophilia in rats by vitamin E and selenium deficiency

Eosinophilic enteritis and eosinophilia, in addition to muscular dystrophy and occasionally liver necrosis, were experimentally induced in male Sprague-Dawley rats with a vitamin E- and selenium-deficient diet (basal diet) for 9 weeks. Cecum and ileum were affected more frequently and severely than other segments of the gastrointestinal tract. Eosinophils were multifocally or diffusely distributed in the intestinal wall but were most severe in the muscular layer and in the submucosa. Eosinophils were also present in stomach, liver with massive hepatocellular necrosis, and skeletal muscle with marked myonecrosis. Eosinophilic enteritis and eosinophilia were not observed in rats fed the basal diet supplemented with either vitamin E (100 or 200 ppm) or selenium (0.1 or 1.0 ppm). Eosinophilic enteritis, eosinophilia, and muscular dystrophy regressed when vitamin E- and selenium-deficient rats were subsequently fed either the vitamin E- or selenium-supplemented diet for 4-5 weeks. These findings suggest that vitamin E and selenium deficiency may play a role in the development of a diffuse type of eosinophilic enteritis and eosinophilia.

Light-adaptation in the photophobic response by Stentor coeruleus

Effects of preillumination on photophobic response (light-adaptation) and recovery of the photophobic sensitivity in the dark (dark-adaptation) in Stentor coeruleus were examined. When the cells were preilluminated with white light of 7.80 W/m2 for 2 min, the fluence-rate response curve of photophobic response was shifted toward higher light intensities by half an order of magnitude compared to the one without preillumination. Preillumination with a higher light intensity resulted in a further shift of the fluence-rate response curve. An action spectrum for light-adaptation showed a primary peak at 610 nm and secondary peaks at 540 and 480 nm which are almost identical to the peaks observed in the photophobic action spectrum. The light-adapted cells showed a recovery of their photophobic sensing ability following dark treatment. Dark-adaptation resulted in total recovery of photophobic sensing ability in 8 minutes for the most cases examined.

Effect of dietary vitamin E on nitrite-treated rats

The effect of dietary vitamin E on cellular responses to nitrite was studied in rats. One-month-old male Sprague-Dawley rats were fed a basal vitamin E-deficient diet with or without 100 ppm vitamin E and 1000 ppm sodium nitrite (NaNO2) for 9 weeks. In addition to a high mortality rate, nitrite-fed rats maintained on a vitamin E-deficient diet exhibited a marked increase in liver necrosis, tubular nephrosis and myodegeneration, as well as greater biochemical and hematological alterations when compared to the control animals. No animal mortality or histopathologic lesions in any tissues were observed in rats receiving a vitamin E-supplemented diet with or without nitrite. The results suggest that depletion of vitamin E renders rats more susceptible to the adverse effect of nitrite, and that nitrite administration potentiates deficiency of vitamin E in rats.

Subacute and chronic toxicity studies of trinitroglycerin in dogs, rats, and mice

Subacute and chronic oral toxicities of trinotroglycerin (TNG) were studied in beagle dogs, CD rats, and CD-1 mice. No adverse effects were seen in dogs given up to 1 mg/kd/day of TNG for 4 weeks, then 5 mg/kg/day for 9 more weeks. Dogs given 25 to 200 mg/kg/day for 5 days had transient and dose-related severe methemoglobinemia, while 200 mg/kg/day produced depression; dogs given 1, 5, or 25 mg/kg/day for 12 months had transient and dose-related mild methemoglobinemia. Rats fed 0.1% TNG for 5 weeks, then 0.5% (230-234 mg/kd/day) for 8 more weeks had decreases in feed consumption and weight gain after the increase in dosage; rats fed 2.5% TNG (1406 or 1416 mg/kg/day for males and females, respectively) for 13 weeks suffered adverse effects, including weight loss, compensated anemia, and testicular degeneration, but they resumed gaining weight as feeding continued. Rats fed 1% TNG (363 or 434 mg/kg/day for males and females, respectively) for 2 years had decreased weight gain, decreased grooming, methemoglobinemia and its sequelae, cholangiofibrosis , hepatocellular carcinoma, and interstitial cell tumors of the testis. A decrease in the naturally occurring pituitary chromophobe adenoma and mammary tumors increased the life span of the females. Some rats fed 0.1% TNG (31.5 or 38.1 mg/kg/day for males and females, respectively) had mild hepatic lesions similar to those seen in rats fed the larger doses. No adverse effects were seen in mice fed up to 0.1% TNG for 3 weeks, then 0.5% for 10 more weeks. Mice fed 1% TNG (1022 or 1058 mg/kg/day for males and females, respectively) for 2 years had decreased weight gain, decreased grooming, and methemoglobinemia and its sequelae, but no obvious cellular changes as found in the rats.

Myodegeneration in Kentucky white-tailed deer

Skeletal or cardiac myodegeneration, or both, was observed in 4 free-ranging female white-tailed deer that were found dead or recumbent and unable to rise. Gross pathologic findings included white or chalky streaks in heart or skeletal musculature. Degeneration, necrosis, and mineralization were observed microscopically in affected striated muscles. Although the precise cause of myodegeneration was not determined, changes were considered compatible with nutritional or exertional myopathy.

The effect of L-3, 4-dehydroproline on the antitumor activity and toxicity of bleomycin

Pulmonary fibrosis is a serious side effect that limits the therapeutic utility of bleomycin (BLM). Recently, it has been demonstrated that L-3, 4-dehydroproline (DHP), a proline analog, significantly reduced the extent of pulmonary fibrosis in rats administered BLM intratracheally. The present studies were performed to determine the effect of DHP on the oncolytic and toxicologic effects of BLM. DHP (25 mg/kg/day) administered sc concomitantly with BLM (4 mg/kg/day) for 9 consecutive days following a sc inoculation of B16 melanoma cells in BDF1 had no effect on tumor growth inhibition by BLM when tumor growth rate was assessed by tumor volume and by tumor weight. To determine the effect of DHP on the toxicity of BLM, DHP (25 mg/kg/day) and BLM (10 mg/kg/day) were administered to Sprague-Dawley rats for 5 consecutive days followed by 2 days of rest and 5 additional days of drug administration. BLM administration produced decreased body weight gain, acute leukocytopenia, delayed elevation in blood nitrogen levels, chronic lung and kidney disease, and alopecia. Animals administered BLM plus DHP had a similar toxicologic profile. One striking difference was that no animal administered BLM plus DHP developed alopecia, whereas five of eight rats administered BLM alone displayed this untoward effect. These results suggest that DHP neither diminishes the oncolytic activity nor exacerbates the nonpulmonary toxicity of BLM, DHP would appear, therefore, to be a potential candidate as an antifibrotic adjunct to BLM therapy.

Sarcocystosis in an aborted bovine fetus

Sarcocystosis was diagnosed in an aborted bovine fetus. Immature and mature schizonts of Sarcocystis were disseminated in the vascular endothelium of all organs, but especially the brain. Microscopic granulomas, focal gliosis, and petechial hemorrhages in the neuropil were scattered in the brain. Multifocal collections of mononuclear cells were observed in the kidney, liver and heart. Organisms in sections of frozen tissues were demonstrated by immunofluorescent techniques to be Sarcocystis.

Follow-up study on the carcinogenicity of vinyl chloride and vinylidene chloride in rats and mice: tumor incidence and mortality subsequent to exposure

Carcinogenic and other toxic effects in rats and mice were examined during a 12-mo period following exposure to vinyl chloride (VC) or vinylidene chloride (VDC). Exposure of male and female mice to 50, 250, or 1000 ppm VC for 6 h/d, 5 d/wk, for 1, 3, or 6 mo resulted in increased numbers of deaths and increased moribundity at all dose levels during the exposure and postexposure periods, as compared with air-exposed controls. Similar observations were made with rats after 1, 3, 6, or 10 mo exposure to VC. Cumulative tumor incidence at various organ sites also increased in both species during the postexposure period in proportion to dose or duration of exposure at higher dose levels. However, except for mammary gland tumors in female mice, no significant increase in cumulative tumor incidence occurred in either species at 50 ppm VC or 55 ppm VDC, regardless of duration of exposure. These results suggest that exposure to vinyl halides at dose levels lower than those that elicit a significant increase in cancer incidence during the lifetime of the animal may, nonetheless, increase the risk of early death or moribundity from toxic pre- or subcarcinogenic effects. At dose levels higher than those consistent with the physiological defense or repair capabilities of the cell, ultimate tumor incidence becomes proportionate to length of exposure and may reflect the number of carcinogenic events elicited during the exposure period.

Cremophor and Emulphor induced alterations of serum lipids and lipoprotein electrophoretic patterns of dogs

The effects of Cremophor and Emulphor, two polyethoxylated castor oil vehicles, on serum lipids and lipoproteins electrophoretic patterns were examined in beagle dogs. The vehicles were given as daily intravenous (i.v.) infusions of 0.5 ml/kg. Flushing of the skin, edematous wrinkling of the skin above the eyes and shaking of the head were observed during or shortly after each infusion of either vehicle. Thrombocytopenia occurred in Emulphor-treated dogs but increased platelet counts occurred in Cremophor-treated dogs. The spleen, lymph nodes, livers and kidneys all had excessive amounts of lipid present. There were increased serum levels of triglycerides, lipids, cholesterol and lipoproteins. Electrophoresis of sera revealed decreased alpha-lipoprotein fraction and the appearance of a new, as yet unidentified, peak near the origin. The lipid and lipoprotein changes were more marked in dogs treated with Cremophor. It appears that daily infusion with either vehicle results in changes in serum lipids, lipoprotein patterns and tissue lipid content.

Hepatic angiosarcoma. Animal model: angiosarcoma of rats and mice induced by vinyl chloride

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Toxicity of vinylidene chloride in mice and rats and its alterations by various treatments

The toxicity of vinylidene chloride (VDC) was studied in mice and rats exposed to various concentrations of the vapors for 23 hr/day. In addition, the ability of various compounds to alter parameters of toxicity was evaluated. Mice were more sensitive than rats to the lethal, hepatotoxic, and renal toxic effects of VDC. Disulfiram protected mice from these toxic effects of inhaled VDC and reduced the levels of covalently bound radioactivity in the liver and kidney after the ip administration of [14C] VDC. Diethyldithiocarbamate and thiram also protected mice from the acute lethal effects of VDC.