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Elevated bile acids in the plasma of laying hens fed rapeseed meal.

A simple procedure was developed for the estimation of bile acid taurine conjugates in fowl plasma. Laying hens fed a diet containing rapeseed meal (RSM) (400 g kg-1) for 12 weeks had higher bile acid levels (154 mumol litre-1) than hens fed a control soyabean diet (116 mumol litre-1) (P less than 0.01). The incidence of liver haemorrhages was higher (34.8 per cent) in RSM-fed hens than in controls (21 per cent), but the severity of the lesions did not correlate with the bile acid concentration in affected birds. Histological examination of sections from livers of RSM-fed birds did not reveal significant hepatocyte degeneration outside the immediate vicinity of the haemorrhage. Canalicular bile plugs were never seen. The incidence of liver haemorrhages (13 per cent) and plasma bile acids (85 mumol litre-1) were lower in hens fed a diet containing beta-aminopropionitrile (0.5 g kg-1), a known lathyrogen. Acute treatment of hens with the hepatotoxin alpha-naphthyl isothiocyanate over four days induced necrosis of hepatocytes and resulted in elevated bile acid concentrations (262 mumol litre-1) compared with controls (73 mumol litre-1) given arachis oil. It was concluded that laying hens fed high levels of RSM develop cholestasis but the toxic principle is not known.

Animal Feed↗

Lathyrism: a neurotoxic disease.

Lathyrism, one of the oldest neurotoxic diseases known to Man, results from excessive consumption of the chickling pea, Lathyrus sativus, and certain related species. Once prevalent throughout Europe, N. Africa, Middle East and parts of the Far East, the disease is presently restricted to India, Bangladesh and Ethiopia. Lathyrism is a form of irreversible, non-progressive spastic paraparesis associated with poorly understood degenerative changes in spinal cord. Domestic animals, notably the horse, also develop hindlimb paralysis after prolonged feeding on lathyrus fodder. Experimental animal models of lathyrism have been reported but none has been satisfactorily investigated, and concurrence between these experimental diseases and the human condition is unproven. The culpable agent in lathyrus species that precipitates paralysis also is unknown. Current attention is focused on the glutamate analog, beta-(N)-oxalyl-amino-L-alanine acid (BOAA). While this compound is present in those lathyrus species that induce spastic paraparesis and, in large doses, reportedly causes neuropathological changes similar to glutamate neurotoxicity, there is little to compare these neuropathological changes with those found in human lathyrism. Chronic primate feeding studies utilizing BOAA need to be carried out to determine whether this agent is responsible for human lathyrism. Some species of lathyrus, notably Lathyrus odoratus, are unable to induce human lathyrism but contain a compound, beta-aminopropionitrile (BAPN), that induces pathological changes in bone ("osteolathyrism") and blood vessels ("angiolathyrism") of experimental animals without damaging the nervous system. However, related compounds, dimethylaminopropionitrile (DMAPN) and beta, beta'-iminodipropionitrile (IDPN), are chronic neurotoxins in humans and animals, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids, Diamino↗

[Communicating acute aortic dissection (pathogenetic study)].

Thirty-five dissecting aneurisms of the aorta (D.A.). have been microscopically and ultramicroscopically examined. These data have been compared to those obtained from personal experiences on human aorta aging, as well as from Beta Aminopropionitrile treated rats. The authors conceive D.A. as a non-obligatory complication of a precocious and intense medianecrosis of the aortic wall, particularly characterized by a mucous imbibition and a loss elastic laminae. This medianecrosis is identical in dysplasic D.A. (Martan's syndrome for example) and in acquired D.A. (rapid aging or arteriosclerosis). The simultaneous occurence of a medianecrosis and conditions triggering tunica intima rupture, with blood afflux in the necrotic zone are undoubtedly rare. This explains the small number of observed D.A. in comparison to the large number of aortas with accentuated medial lesions.

Aged↗

Sulphate turnover of surface proteoglycans in cultured rat smooth muscle cells.

Turnover of radioactive sulphate-labelled proteoglycans in cultured rat smooth muscle cells was detected by pulse chase techniques. The degradation appeared to take the form of desulphation of sulphated macromolecules, with a loss in total sulphate of approximately 50% in 5 days. The desulphation process occurred in the pericellular/matrix compartment of the culture system and was unaffected by inhibition of matrix formation by beta-aminopropionitrile, or by incubation of cells with lysomotropic inhibitors. There was no evidence for further degradation of desulphated species even when exogenous, radio-labelled proteoglycans were added to fresh cultures and incubated for four days. Labelled macromolecules initiated on xyloside acceptors were desulphated by rat smooth muscle cell cultures more slowly than intact proteoglycans.

Animals↗

Considerations of copper metabolism in osteochondrosis of suckling foals.

Of 8 Thoroughbred foals in which osteochondrosis developed before weaning, 7 had serum copper and ceruloplasmin concentrations below normal. Three foals on one farm had serum zinc content high enough to suggest zinc toxicosis, and the liver of each foal contained abnormally high content of zinc. Four foals from the second farm had extremely low serum copper content, but normal serum zinc content. Evidence of environmental exposure to excess zinc was not found on either farm. The lesions in the zones of endochondral ossification of the afflicted foals were similar in many respects to those found in other species of animals with molybdenum-induced copper deficiency and with inhibition of the function of copper-dependent lysyl oxidase by beta-aminopropionitrile, a toxic component of Lathyrus odoratus known to cause osteolathyrism.

Animals↗

Processing of procollagen types III and I in cultured bovine smooth muscle cells.

The processing of type III and type I procollagen molecules in cultured bovine aortic smooth muscle cells was investigated. The molecular identities of the processing intermediates of type III and type I procollagen were characterized by analysis of the radioactive collagenous components using mammalian collagenase and pepsin digestions and cyanogen bromide peptide mapping. The results indicate that the processed intermediates for procollagen type III and type I are their respective pC components. Although the processing pathways for both collagen types are the same, data from pulse-chase experiments suggest that the rates at which the processing occurs are different. Type I procollagen is processed more rapidly to its intermediate than is type III procollagen. The type I pC intermediate is almost completely processed to alpha-chains and a significant portion of these fully processed molecules remains in a soluble form even after 11 h. In the same time period, the type III pC intermediate is slowly converted to alpha-chains. Since beta-aminopropionitrile was not employed in these studies, significant accumulation of collagen chains into the insoluble extracellular matrix was observed during the chase period.

Animals↗

Stimulation of collagen biosynthesis by platelet homogenate in various cell cultures.

Confluent cultures of Balb c/3T3, L-929 and PZ-32 cells were incubated at 37 degrees C for 16 h in the serum-free culture medium supplemented with ascorbic acid, beta-aminopropionitrile and (5(-3) H)proline. An addition of platelet homogenate to the culture medium increased significantly proline incorporation into proteins and synthesis of the hydroxyproline-containing, collagenase-sensitive proteins.

Animals↗

Collagen fibril assembly in the developing avian primary corneal stroma.

PURPOSE: The primary stroma of the developing avian cornea is a highly organized extracellular matrix composed largely of striated collagen fibrils synthesized by the epithelium. These fibrils are heterotypic structures consisting of at least two different fibrillar collagen types (I and II) and probably a fibril-associated collagen (type IX). The epithelial derivation and vectorial secretion of the components of this matrix provide an advantageous system to study the steps in the assembly of this developmentally regulated matrix, as well as in the assembly and maturation of heterotypic collagen fibrils in general. To ascertain when and where two of the collagens of the primary stroma (collagen types II and IX) are assembled into fibrils, monoclonal antibodies were used that bind to the newly deposited, "immature" (non-cross-linked) forms of these molecules, but not to ones that have been assembled into fibrils and have become cross-linked. METHODS: The patterns of immunoreactivity for newly deposited versus total collagens were compared by immunofluorescence histochemistry on sections of corneas from developing chicken embryos. Pretreatments that affect collagen cross-linking and enzymatic digestions with collagenase also were used. RESULTS: In early corneas, immunoreactivity for the newly deposited forms of both collagen types II and IX was confined to a narrow subepithelial zone, their epitopes being masked in the deeper layers of the stroma. The masked immunoreactivity could be exposed in these layers by inhibiting cross-link formation with beta-aminopropionitrile. At later developmental stages, after the stroma has swollen and become invaded by mesenchymal cells, type IX collagen is no longer detectable either as an "immature" or as a fibril-associated form. During most of this period, the distribution of "immature" type II collagen is noticeably more restricted to the subepithelial zone than is total type II. Much of the undetectable immunoreactivity for collagen type II could be "unmasked" in deeper stromal layers by brief digestions with bacterial collagenase as well as by inhibition of cross-link formation. The extent of such unmasking of type II, however, is more limited in older corneas, suggesting that some of the putatively masked epitopes at these stages may in fact be proteolytically degraded. CONCLUSIONS: These results conform with previous studies suggesting that the type II and type IX collagens of the primary stroma are derived from the epithelium. They also suggest that (1) the assembly and maturation of the heterotypic fibrils, including the addition of the fibril-associated collagen type IX and covalent cross-link formation, occur shortly after synthesis and secretion of the molecules; (2) most, if not all, of the corneal type IX collagen becomes fibril-associated; and (3) during much of corneal development the N-telopeptide epitope in type II collagen is largely retained in a sterically masked form, but in later stages, during remodeling it may be removed by proteolytic degradation.

Animals↗

Elastic fiber abnormalities associated with a leaflet perforation in floppy mitral valve.

The alterations observed in the elastic fibers of the perforated floppy mitral valve of a 68-year-old man are described. The patient had not history of infective endocarditis and no stigmata of Marfan syndrome or Ehlers-Danlos syndrome. Ultrastructurally, the elastic fibers in the area of the perforation showed unique, round-shaped expansion of the amorphous components, which lacked associated microfibrils. These features resembled those of the elastic fibers in animals treated with beta-aminopropionitrile, an inhibitor of lysyl oxidase. Aggregations of microfibrils without amorphous components were also observed. These abnormalities are considered to be related to the pathogenesis of the perforation in this valve.

Aged↗

COLLAGEN METABOLISM IN THE NORMAL AND LATHYRITIC CHICK.

1. Radioisotope incorporation studies of normal and lathyritic chick embryo bone collagen do not demonstrate any interference by lathyrism with collagen synthesis or fibril formation. 2. The results indicate that a portion of the extractable collagen from lathyritic chick embryo bone represents newly synthesized protein. Evidence from a double labeling experiment and from analysis of isotope flow between the extractable and non-extractable pools suggests the extractable lathyritic collagen is heterogeneous. We propose that the lathyritic process affects collagen in all states of aggregation, probably in varying degree. 3. Puromycin, administered intravenously, reduces the amount of extractable collagen in both normal and lathyritic chick embryo bone, and diminishes the incorporation of labeled proline into collagen. 4. Marked fluctuations in incorporation of labeled amino acids into chick embryo bone collagen suggests the occurrence of wide fluctuations in metabolism of this protein.

Amino Acids↗