The fine structure and histochemistry of human bile duct in obstruction and choledocholithiasis

Biopsies from the common bile ducts from seven patients undergoing surgery for biliary obstruction due to stones or malignancy were studied histochemically and electron microscopically. The surface of the bile duct is lined by a tall epithelium which extends into diverticula. Apically, they contain some neutral and sialated mucosubstances. Fucosyl residues were found in the Golgi apparatus and along the apical cell membrane. The latter is lined by microvilli. There was a well-developed rough endoplasmic reticulum and Golgi apparatus and a small number of apical secretory droplets. Large numbers of lipid droplets were present basally in some cells. Lipid-containing macrophages were also seen intra-epithelially and in the lamina propria. This suggests a possible pathway for lipid transport. The glands were lined by cuboidal cells, some containing much mucus--sulphated, sialated, and neutral with a basal nucleus. A well-developed endoplasmic reticulum and Golgi apparatus were found with abundant secretory droplets. The glandular epithelium contained lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin. These may play a protective role. The lamina propria contained scattered smooth muscle cells amongst the fibroblasts and inflammatory cells.     

Effect of α1-protease inhibitor (α1-antitrypsin on the intensity of transformation of phytohemagglutinin-stimulated lymphocytes

₁-Antitrypsin (₁-AT) reduces the intensity of transformation of human peripheral blood lymphocytes stimulated by phytohemagglutinin. The degree of inhibition is determined by the antiprotease activity of the ₁-AT. Maximal inhibition of transformation was shown to be 50%. Participation of ₁-AT in the control of activity of lymphoid tissue cells is postulated.Laboratory of Immunogenetics, Research Institute of Transplantology and Artificial Organs, Ministry of Health of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 1, pp. 35–36, January, 1980.     

Immunohistochemical findings in rheumatoid nodules

Summary Eighteen nodules from patients with rheumatoid disease were studied histologically and immunohistochemically. A continuum of microscopic changes was observed with varying degrees of fibrinoid necrosis, mononuclear cell infiltration and healing by fibrous scarring. In two cases there was focal evidence of arteritis. Fibrin was plentiful in the necrotic areas of nodules. Small amounts of immunoglobulin were identified in plasma cells and as irregular extracellular deposits in and around areas of necrosis. In a single small vein abnormal IgG was detected.Mononuclear cells surrounding areas of necrosis stained strongly with antisera to ferritin and a cytoplasmic macrophage antigen, stained variably with muramidase (lysozyme) and negatively with alpha-1 antitrypsin antibodies. Perls' stain for ferric iron was almost entirely negative and ultrastructural x-ray microanalysis indicated that the cytoplasm of these cells were entirely free of iron. These findings confirm the chronic inflammatory nature of rheumatoid nodules but provide no support for the view that they originate in areas of vasculitis. A relative lack of cytoplasmic antiprotease along with a strong expression of ferritin appears to be a characteristic feature of macrophages in rheumatoid tissue.     

Granulocyte elastase-mediated proteolysis of alpha 1-antitrypsin in cystic fibrosis bronchopulmonary secretions

Airway secretions of patients with cystic fibrosis (CF) contain large amounts of alpha 1-antitrypsin (alpha 1-AT), yet elastase activity is also often detectable, suggesting that airway alpha 1-AT may not be functional in some CF patients. It is unknown whether in CF sputum alpha 1-AT is inactivated by oxidants, neutrophil metalloproteinases, bacterial elastase, or neutrophil elastase. To investigate the mechanism(s) by which alpha 1-AT may be inactivated in CF airway secretions, sputum samples were obtained from nine patients during respiratory physiotherapy. alpha 1-AT was measured by radial immunodiffusion. Sputum-alpha 1-AT was purified by antibody affinity chromatography. Electrophoresis of alpha 1-AT from seven patients with acute infectious exacerbations revealed two distinct components: a minor band corresponding to an elastase/alpha 1-AT complex and a major band typical of proteolysed alpha 1-AT (Mr = 48 kD). Each patient had large amounts of sputum elastase activity. In contrast, two patients without free sputum elastase activity had intact sputum alpha 1-AT; however, alpha 1-AT was partially truncated by porcine pancreatic elastase suggesting that the alpha 1-AT may have been partially oxidized. Adding alpha 1-AT purified from normal serum to alpha 1-AT-depleted sputum containing elastase activity resulted in a small alpha 1-AT/elastase complex with most alpha 1-AT being truncated. The serine proteinase inhibitor phenylmethylsulfonyl fluoride but not the metalloproteinase inhibitor EDTA prevented alpha 1-AT proteolysis, thus granulocyte elastase can mediate alpha 1-AT degradation in CF. Apparently, the large granulocyte elastase burden in some acutely ill patients with cystic fibrosis can proteolytically inactivate alpha 1-AT.     

Transepithelial transport of prodrugs of the HIV protease inhibitors saquinavir,indinavir, and nelfinavir across Caco-2 cell monolayers

Purpose. This study is dedicated to the permeation of various amino acid-, D-glucose-, and PEG-conjugates of indinavir, saquinavir, and nelfinavir across monolayers of Caco-2 cells as models of the intestinal barrier. This screening is aimed at detecting the most promising prodrugs for improving the intestinal absorption of these protease inhibitors. Methods. The bidirectional transport of the prodrugs was investigated using P-gp-expressing Caco-2 monolayers grown on membrane inserts using high-performance liquid chromatography for quantitation. Results. The L-valyl, L-leucyl, and L-phenylalanyl ester conjugates led to an enhancement of the absorptive flux of indinavir or saquinavir. These results are likely attributable to an active transport mechanism and/or to a decrease of their efflux by carriers such as P-gp. Connection of tyrosine through its hydroxyl, of D-glucose, or of polyethylene glycol decreased their absorptive and secretory diffusion. Conclusions. Conjugation of the protease inhibitors to amino acids constitutes a most appealing alternative that could improve their intestinal absorption and oral bioavailability. Whether it could improve their delivery into the central nervous system remains to be explored. D-Glucose conjugation will most probably not improve their intestinal absorption or their crossing of the blood-brain barrier. If some pharmacologic benefits are to be expected from PEG-protease inhibitor conjugates, they must then be administered intravenously.     

Protease-antiprotease imbalance in the pathogensis of emphysema and chronic bronchial injury: A potential target for drug development

The hypothesis that emphysema might be caused by an imbalance between proteases and antiproteases in the lungs arose shortly after the discovery of the premature and familial occurrence of emphysema in persons with homozygous alpha-1-protease inhibitor deficiency. Experimental evidence for support of this hypothesis has come from experimental induction of emphysema in animals by proteases. The ability of proteases to induce emphysema is proportional to their elastolytic potency. The importance of elastin degradation as a cause of the development of emphysema has also come from experiments of genetic models in which elastin crosslinking is prevented. The neutrophilis believed to be the most likely source of elastase in the induction of the emphysema of smokers. Alpha-1-protease inhibitor is the most important antiprotease. Alpha-1-antiprotease is susceptible to oxidative inactivation by cigarette smoke or by endogenous oxidants. Oxidants from cigarette smoke may also interfere with proper elastin repair. Serine proteases have also been shown to produce secretory cell metaplasia in the central intrapulmonary bronchi of hamsters. The discovery of secretory leukoprotease inhibitor in sputum and its production by bronchial secretory cells raises the possibility that secretory cell metaplasia in humans may also be caused by an imbalance between proteases and antiproteases. Although evidence for the validity of the proteaselantiprotease hypothesis of the phogenesis of emphysema and chronic bronchitis in human smokers is still indirect, the development of supplemental antiprotease therapy seems rational for the prevention of progression of these diseases in persons who are unable to stop smoking.