Biochemical Mapping of Peptidyl-Glycine α-Amidation Activity in the Rat CNS

Peptidyl-glycine alpha-amidation enzyme activity has been measured in 36 nuclei or areas in the rat CNS and pituitary using D-Tyr-Phe-Gly as the substrate. The distribution of this enzyme is highly uneven, with highest activity levels (greater than 30 pmol/mg of protein/h) in hypothalamic nuclei, substantia grisea centralis, and nucleus ruber; moderate activity levels (10-30 pmol/mg of protein/h) in globus pallidus, septum, midbrain, pons, medulla oblongata, and cervical spinal cord; and low activity levels (1-10 pmol/mg of protein/h) in other telencephalic and thalamic structures. Almost no alpha-amidation activity (less than 0.5 pmol/mg of protein/h) was detected in cerebellar cortex. The Km values in several brain regions are of the same order.     

Cytochemical changes in hepatocytes of rats with endotoxemia or sepsis: localization of fibronectin, calcium, and enzymes

Bacterial lipopolysaccharide (LPS) is known to be implicated in the pathogenesis of endotoxemia and septic shock. The liver is the first vital organ to exhibit pathological alterations in shock. The present studies include immunoelectron microscopic localization of tissue fibronectin and cytochemical localization of calcium and enzymes in hepatocytes of animals with LPS-induced endotoxemia or cecal ligation-induced septic shock. The results showed increased staining of fibronectin in the basal (perisinusoidal) surfaces and in the cisternae of rough endoplasmic reticulum and the Golgi complex of hepatocytes in rats with endotoxemia or septic shock. Intracellular calcium content was significantly increased in the LPS-treated or septic rats. Calcium pyroantimonate precipitate was deposited predominantly on the outer surfaces of the RER of hepatocytes. In addition, diminution or depletion of glycogen, reduction of catalase-containing peroxisomes, increase of G-6-Pase activity, and depletion of cytochrome c oxidase in many mitochondria were also observed in hepatocytes of experimental animals. The overall results suggest that LPS stimulates: (a) hepatic synthesis and secretion of fibronectin; (b) uptake of calcium by hepatocytes; and (c) G-6-Pase activity. LPS treatment also leads to reduced numbers of peroxisomes and depletion of cytochrome c oxidase.     

Collagen autoimmunity and arthritis

Collagen-induced arthritis in animals is an example of polyarthritis that sufficiently resembles human rheumatoid arthritis to be used as a model. It is caused by immunizing susceptible animals with type II collagen isolated from articular cartilage. Susceptibility is genetically determined and linked to the major histocompatibility locus. It is important because some human arthritis is also associated with major histocompatibility genes and may be caused or aggravated by the presence of autoimmunity to normal cartilage components. Collagen-induced arthritis is also important because it is an example of immunologically mediated joint destruction, which may share some of the mechanisms present in human disease. Although it is caused by autoimmunity to collagen, susceptibility and responsiveness to type II collagen are not completely correlated, and there are examples of animals with high levels of collagen immunity who do not develop arthritis. The initial lesion appears to be the deposition of an antibody on the surface of articular cartilage, which precedes development of overt arthritis by several days. Disease can be readily transferred with specific antibody. Arthritogenic antibodies appear to have restricted epitope specificity, which may partially explain the disparities between responsiveness to immunization with collagen and susceptibility to arthritis, but precise delineation of the epitopes involved has not yet been accomplished. Complement activation also appears to be intimately involved since the disease correlates with the presence of high levels of complement-binding IgG isotypes, and passive transfer is possible only into complement-sufficient recipients. Inflammation progresses rapidly so that cartilage destruction and marginal erosion develop over a period of a few days. Collagen-induced arthritis offers a unique opportunity to study autoimmune-mediated arthritis in which the inducing antigen is well characterized and readily available. Analysis of the disease has permitted the proposal of a schema for its pathogenesis.     

Differential expression of K+ channel mRNAs in the rat brain and down-regulation in the hippocampus following seizures.

K+ channels are major determinants of membrane excitability. Differences in neuronal excitability within the nervous system may arise from differential expression of K+ channel genes, regulated spatially in a cell type-specific manner, or temporally in response to neuronal activity. We have compared the distribution of mRNAs of three K+ channel genes, Kv1.1, Kv1.2, and Kv4.2 in rat brain, and examined activity-dependent changes following treatment with the convulsant drug pentylenetetrazole. Both regional and cell type-specific differences of K+ channel gene expression were found. In addition, seizure activity caused a reduction of Kv1.2 and Kv4.2 mRNAs in the dentate granule cells of the hippocampus, raising the possibility that K+ channel gene regulation may play a role in long-term neuronal plasticity.     

Metacercarial infections of Paragonimus westermani in freshwater crabs sold in markets in Seoul

Status of metacercarial infections of Paragonimus westermani was observed in freshwater crabs, which were purchased at 3 markets in its peak season of 1990. All of 85 crabs were Eriocheir japonicus. No other species of Eriocheir were found. When crushed muscle and viscera was examined individually, the infection rate was 11.8%; and mean number of metacercariae was 2.1 per infected crab. Unless adequately cooked, freshwater crabs are still potential sources of human paragonimiasis.     

Component proteins in crude extract of adult Paragonimus westermani purified by immunoaffinity chromatography using monoclonal antibodies.

The nature of 2 component proteins in crude saline extract of adult Paragonimus westermani was investigated. By immunoaffinity chromatography using monoclonal antibodies (MAb) as ligands, the proteins were purified from the crude extract. Band 1 protein in disc-polyacrylamide gel electrophoresis (PAGE) was purified by PFCK-136 MAb. The protein, known to have molecular mass of 440 kDa, was composed of 23, 46 and 92 kDa subunits when observed by reducing SDS-PAGE and SDS-PAGE/immunoblot. This protein was originated from eggs of the worm as revealed by immunohistochemical staining with PFCK-136 Mab. Another affinity purified protein utilizing PFCK-44 MAb was the band 4 protein of 17 kDa in disc-PAGE. This was a monomer protein in reducing SDS-PAGE and SDS-PAGE/immunoblot. The protein was produced at intestinal epithelium of the worm.     

A comparison of chloride, bromide, and sucrose dilution volumes in neonatal pigs

Use of 36Cl, 82Br, and [3H]sucrose to estimate extracellular water volume was evaluated in 14 piglets (7-14 days old). 36Cl and 82Br were distributed in approximately the same volume, but a period of 5-6 hr after injection was required to reach equilibrium in the neonatal pig. Dilution volumes calculated before equilibration (2-5 hr) for 36Cl (326 +/- 11 ml/kg) and 82Br (328 +/- 13 ml/kg) were different from equilibration (6-8 hr) phase volumes (356 +/- 13 ml/kg and 355 +/- 13 ml/kg, respectively; P less than 0.001). A 3-hr sample estimated the same volume distribution calculated by extrapolation of the 6- to 8-hr period because of the relationship between the two slopes of the plasma clearance curves. After the 82Br and 36Cl had achieved equilibration, each was distributed in a volume equivalent to total body chloride space (362 +/- 29 ml/kg) measured by neutron activation; no statistical differences were found (P = 0.6). The early equilibration phase measured a 10% smaller, faster exchangeable fraction of total body Cl. Sucrose dilution volume (332 +/- 19 ml/kg) required multiple plasma samples for extrapolation and measured a dilution volume 7% smaller (P less than 0.05) than total body chloride space.