Liver and biliary system pathology in equine dysautonomia (grass sickness)

Hepatocellular and hepatobiliary damage was assessed in equine acute, subacute and chronic grass sickness cases (AGS, SAGS, CGS). Histopathological analysis showed that even in some early AGS cases enlarged hepatocytes, hepatocyte vacuolation indicative of lipid accumulation (steatosis), intrahepatocyte, canalicular and periportal deposition of pigments, frequent leucocyte infiltration and cholangitis occurred. Analysis of serum indicated significantly increased levels of unconjugated bilirubin in all groups and conjugated bilirubin in AGS and SAGS groups, increased levels of bile acids in some individuals from each group and significantly increased levels of glutamate dehydrogenase (GLDH) in AGS and SAGS cases. Conjugated bilirubin was significantly elevated in urine of AGS and SAGS cases. The evidence suggests that abnormal liver function involving moderate hepatocellular pathology in conjunction with steatosis and cholestasis may contribute to the pathogenesis of GS.

A monoclonal antibody that enables specific immunohistological detection of prion protein in bovine spongiform encephalopathy cases

The specificity of a monoclonal antibody (mAB) raised against recombinant bovine prion protein (PrP) for the immunohistological detection of PrP accumulation in the medulla oblongata of bovine spongiform encephalopathy (BSE) and ovine scrapie cases was investigated. mAB KG9 showed a diffuse low intensity reaction with the cytoplasm of neurones in normal cattle and sheep sections. In BSE sections the mAB detected widespread granular deposits of PrP associated with neurones and the neuropil. Although scrapie sections showed similar levels of granular deposits with another antibody to PrP these were not detected by KG9 which did however detect diffuse staining in neuronal cytoplasm. Possible explanations for the specificity of binding of KG9 are discussed.

Establishment and characterization of equine autonomic ganglion cell lines to enable direct testing of candidate toxins involved in equine dysautonomia (grass sickness)

To enable direct testing of a range of potential toxins or pathogens that might be involved in grass sickness, equine thoracic sympathetic chain ganglion cell lines were established from primary cell cultures by retroviral-mediated transduction of the temperature-sensitive mutant of the establishment oncogene encoding SV40 large T antigen. Morphological and behavioral features, temperature dependence, and immunocytochemical characteristics of the cell lines were investigated. The majority of cells were noradrenergic neurons in which dopamine-beta-hydroxylase, the enzyme that catalyzes norepinephrine synthesis, and neuropeptide Y coexisted. Cells treated with plasma from grass sickness cases that had previously been shown to induce autonomic nervous system damage when injected into normal horses showed significantly decreased mitochondrial function after 1 day. After 3 days exposure most cells showed severe degeneration in contrast to those treated with normal plasma. Liver and lung cell lines were also susceptible to plasma, suggesting that the toxin is not specifically neurotoxic.

Investigation of the susceptibility of equine autonomic neuronal cell lines, clonally derived from the same paravertebral ganglion, to toxic plasma from equine dysautonomia (grass sickness) cases

In the autonomic nervous system (ANS) of equine grass sickness (GS) cases, some neurones show abnormal changes while neighbouring neurones are unaffected. To test whether noradrenergic neurones showed variable susceptibility to the GS toxin in culture, clonally-derived populations isolated from the same fetal thoracic sympathetic chain ganglion were challenged with plasma from GS cases previously shown to induce ANS damage when injected into normal horses. During the early stages of exposure to toxic plasma, cells within a clonal population showed variable susceptibility ranging from no obvious effect to characteristic patterns of pathology. However, after 3 days of exposure to toxic plasma all cells were killed. Dose response analysis on selected clonal populations showed no significant difference in TD(50) values.

Growth, nutritional status, body composition, and energy expenditure in prepubertal children with Alagille syndrome

OBJECTIVES

To describe the patterns of growth, nutritional status, body composition, and resting energy expenditure (REE) in prepubertal children with Alagille syndrome (AGS) before the onset of end-stage liver disease.

STUDY DESIGN

Thirteen prepubertal subjects with AGS (8 male; mean age, 6.8 2.8 years) were evaluated for growth parameters, body composition by skinfolds and by dual-energy x-ray absorptiometry, and REE by indirect calorimetry. The children with AGS were compared with a healthy, age-matched reference group of 37 prepubertal children.

RESULTS

Compared with healthy children, children with AGS had significantly reduced (P <. 05) growth (weight, weight z score, height, height z score), nutritional status (midarm circumference, triceps skinfold, and midarm muscle area), and body composition (fat mass and fat-free mass). Subscapular thickness, percent body fat, and REE were not different. The AGS subgroup (n = 4) with REE greater than 110% predicted value had a reduced percent body fat (P <.02).

CONCLUSIONS

Growth and body composition abnormalities are common in prepubertal children with AGS.

Generation of an ovine bone marrow-derived myelomonocyte-like cell line by retroviral-mediated transformation. Immunological characterization and the effect of cytokines and lipopolysaccharides

A cell line (designated BMpXT1) was generated from sheep bone marrow using the Moloney murine leukemia virus-based retroviral vector pXT1. BMpXT1 cells resembled mature alveolar macrophages in being adherent and esterase positive, in expressing certain cell surface antigens, and in secreting granulocyte-macrophage colony-stimulating factor (GM-CSF) when stimulated by ovine interferon-gamma and lipopolysaccharide (LPS) in combination. The absence of a proliferative response to ovine GM-CSF and macrophage colony-stimulating factor, the absence of other cell antigens found in mature macrophages, and low-efficiency phagocytosis suggested that the cells may be at an intermediate to late stage of myelomonocytic differentiation.

Variable efficiency of retroviral-mediated gene transfer into early-passage cultures of fetal lamb epithelial, mesenchymal, and neuroectodermal tissues

The relative efficiency of retroviral-mediated gene transfer into early-passage cultures of different tissues of fetal lamb was investigated. Monolayer cultures prepared by plating 1 x 10(6) cells were infected with the Moloney murine leukemia (MoMLV)-based vector pZIP Neo at a multiplicity of infection (moi) of approximately 1 pfu per 2 x 10(2) recipient cells prior to selection for neomycin resistance. At the low moi used, cells from different tissues showed marked differences in efficiency of colony formation in the descending order: brain > kidney > muscle, lung > skin. Brain cells were transduced at least an order of magnitude more efficiently than other cell types, despite the doubling time of brain cell cultures being five times as long. Cultures were analyzed by morphological and immunocytological criteria to determine whether any particular cell types were transduced. A wide variety of morphologically distinct neuron-like and glial-like brain cells were neomycin resistant. The majority of muscle cell colonies were myogenic. Approximately half of the large kidney colonies were epithelial-like. The majority of lung colonies consisted of fibroblasts. The results suggest that cells originating from the surface embryonic germ layer (ectoderm) and/or occupying positions near the fetal external surface have a markedly lower susceptibility to retroviral-mediated gene transduction.

Investigation of association between alpha-1 proteinase inhibitor haplotype and endometritis in the thoroughbred mare

Failure to inhibit proteinases can lead to excessive tissue damage. The possibility that the severity of endometritis in Thoroughbred mares correlates with the haplotypes of plasma alpha 1-proteinase inhibitor (alpha 1-PI) expressed was investigated in two groups of mares. In mares with pyometritis before treatment, the frequency of the N haplotype, which is already high in the Thoroughbred population, was significantly increased when compared with that in a large published population. In mares with acute endometritis which persisted after treatment followed by sexual rest, the absence of S and T haplotypes was significant, suggesting that, when present, they may have a protective function.

Comparative studies of the Spi1 proteins of three equine alpha-1-proteinase inhibitor haplotypes following isolation by affinity chromatography

1. Antiproteinase deficiency can result in excessive proteinase-induced tissue damage. The major anti-elastase (Spi1) protein of equine alpha 1-proteinase inhibitor (alpha 1-PI) was isolated from the plasma/serum of three common haplotypes (I, L and U). 2. The N-terminal amino acid sequences of the three inhibitors were identical, but were only approx 65-77% homologous with two other published equine Spi1 sequences. 3. All three inhibitors complexed quickly and irreversibly with equine leucocyte proteinase 2A (kass = 2 x 10(7) M-1 sec-1). They were also efficient inhibitors of chymase (rat mast cell proteinase-II; kass = 2 x 10(5) M-1 sec-1; Ki = 2 x 10(-10) M). There was therefore no evidence of deficient inhibition in the Spi1 variants of the I,L and U haplotypes.

Retardation of serum albumin migration in native polyacrylamide gel electrophoresis by the incorporation of blue dextran in the gel matrix

Blue dextran was incorporated into the stacking layer of one-dimensional polyacrylamide gels to prevent the migration of albumin into the resolving gel during the electrophoresis of native plasma samples. Human and horse plasma proteins normally masked by albumin were revealed by this method.

Plasma thyroxine levels in Duchenne muscular dystrophy

Some young Duchenne muscular dystrophy (DMD) patients (3-7 years) had total thyroxine (T4) levels and T4 to thyroxine binding globulin (TBG) ratios above the normal range and significantly increased free thyroxine indices (fT4I) which, however, remained within the normal range. Older DMD patients (7-11 years) had T4 and TBG levels and fT4I similar to normal. In both DMD groups the thyroxine binding index (TBI) values were in the normal range.

Microheterogeneity of myelin basic proteins in the partially myelinated spinal roots of the Bar Harbor 129 ReJ muscular dystrophic mouse

The protein composition of normal spinal roots and the partially myelinated spinal roots of Bar Harbor 129 ReJ dystrophic mice was analyzed by 2D-gel electrophoresis which resolved basic proteins. The normal roots contained proteins with mobilities identical to two of the three 18.5 kDa and two of the three 14 kDa myelin basic protein spots resolved in purified spinal cord myelin suggesting that normal root myelin may have some of the characteristics of CNS myelin. In contrast dystrophic roots contained spots with mobilities identical to only one of the spots resolved for each myelin basic protein. The possibility that the difference in microheterogeneity may be responsible for the decreased myelination is discussed.

Elevated plasma levels of haptoglobin in Duchenne muscular dystrophy:electrophoretic variants in patients with a severe form of the disease

Analysis of plasma proteins of Duchenne muscular dystrophy (DMD) patients and normal age-matched boys using two dimensional gel electrophoresis and densitometry indicated a three-fold increase in the average haptoglobin level in DMD plasma. Two electrophoretic variants of haptoglobin in which the alpha 2 chain had more basic or more acidic spots were found in DMD patients with a rapidly progressing form of the disease. The basic variant was present in relatively low amount. Possible reasons for the elevated haptoglobin levels are discussed.

Heterogeneity of human haptoglobin alpha chains detected by two-dimensional gel electrophoresis

The protein spots representing the haptoglobin α1F, α1Sand α2chains in two-dimensional gels of human plasma samples representative of the six common haptoglobin phenotypes were identified by comparing their position with those of purified haptoglobin and distinguished from other spots in the vicinity by comparison with plasma with undetectably low levels of haptoglobin. Silver staining indicated that the α1Fchain was represented by one spot in subtypes 1F-1F, 1F-1S and 1F-2, the α1Schain by three spots in subtypes 1S-1S, 1F-1S and 1S-2 and the α2chain by six spots in 1F-2, 1S-2 and 2–2

Myelin proteins and collagen in the spinal roots and sciatic nerves of muscular dystrophic mice

Proteins of lumbosacral spinal roots and sciatic nerves of adult dystrophic mice (Bar Harbor 129REJ dydy) were analyzed by SDS gel electrophoresis to determine if identifiable proteins were affected. All peripheral nerve myelin proteins (P0 glycoprotein, P1 and Pr basic proteins, X protein and a high-molecular-weight protein) were decreased in the roots but not in the sciatic nerves. Central nervous system myelin proteins were not increased in either roots or sciatic nerves. Although dystrophic spinal roots and sciatic nerves contained less collagen, Type I, III and V collagens were present.

The effect of different collagen types used as substrata on myogenesis in tissue culture

The effect of different collagen types prepared from muscle used as substrata on myogenesis in tissue culture was investigated. Myogenic cells cultured on type I collagen aligned in parallel in some regions of the culture dish and single myotubes could extend for several centimetres. Myotubes grown on type V collagen did not have a normal elongated appearance and were not aligned.

Detection of myosin heavy chain mRNA during myogenesis in tissue culture by in vitro and in situ hybridization

A cDNA copy of purified chick embryonic skeletal myosin heavy chain mRNA (MHC mRNA) distinguished between myogenic and nonmyogenic cells compared by in vitro and in situ hybridization. The majority of cells in replicating mononucleate myogenic cell cultures contained no detectable MHC mRNA. Among the earliest cells to contain MHC mRNA were cells engaged in mitosis. A relatively large amount of MHC mRNA was found in postmitotic monucleate cells and myotubes, and we observed nucleolar localization of MHC mRNA in these cells.

The genes and mRNA coding for the heavy chains of chick embryonic skeletal myosin

A size class of polysomes was isolated from chick embryonic leg skeletal muscle which synthesized almost exclusively a polypeptide chain with a molecular weight identical to the myosin heavy chain. The mRNA purified from these polysomes was shown to synthesize the 200,000 dalton polypeptide in the wheat germ cell-free translation system. At least 90% of the polypeptide had properties similar to the myosin heavy chain. Isoelectric focusing indicated that the myosin heavy chain synthesized in vitro contained two chains in equal amounts, as did purified embryonic leg skeletal muscle myosin. The kinetics of hybridization of the complementary DNA with an excess of the myosin heavy chain mRNA (MHC mRNA) indicated the presence of two different mRNA sequences. Reassociation of the cDNA to an excess of the DNA of the genome suggest that there is little, if any, reiteration of the myosin heavy chain genes.