Effect of cholecystokinin-pancreozymin (CCK-PZ) on glycoprotein secretion from mouse gallbladder epithelium

Summary Structural changes in the gallbladder epithelial cells of the mouse were studied following in vivo and in vitro stimulation of the gallbladder with the gastrointestinal hormone cholecystokinin-pancreozymin (CCK-PZ). Signs of increased secretory activity were observed within the first 2–3 min after hormone administration. At the ultrastructural level, best visualized with the PA-CrA-silver technique, granule discharge was observed, as was an overall increase in size of the granules. After prolonged in vitro incubation or repeated in vivo stimulation, there was an almost total depletion of secretory granules. This phenomenon is accompanied by an enhanced uptake of extracellular thorium dioxide by endocytotic vesicles at the apical cell surface. An exocytosisendocytosis coupling mechanism may be important for membrane conservation in the gallbladder epithelial cells. The findings establish that the hormone CCK-PZ stimulates the secretion of glycoproteins from the mouse gallbladder epithelium.This investigation was supported by grants from the University of Umeå and from the Swedish Medical Research Council (grant No. B76-12X-04758-01). The authors wish to thank Miss K. Karlsson and Miss M. Borg for skilful technical assistance     

Photic evoked responses in the brain stem of the rat]

The appearance of photic evoked responses in various structures of the reticular formation (RF) and the thalamus was investigated in freely moving rats. Photic evoked potentials (PhEP) were recorded in all the nuclei tested. The PhEP are different in shape, amplitude and latency; they can be classified as a "primary type" with small amplitudes and without latency differences from the PhEP of the visual cortex (VC) and as a "secondary type" with large amplitudes and latency differences from the PhEP of the VC. The "primary type" was observed in thalamic, pontine and bulbar structures but the "secondary type" in posterior-thalamic and mesencephalic structures. Photic afterdischarges (PhNE) and photic recruitment (PhR) were recorded in most of the nuclei tested. These PhNE and PhR have a correlation in their frequency and peak-latency to the PhNE and PhR of the VC. It is discussed that a great part of visual information is transferred to the brain stem through the Corpus geniculatum laterale (CGL) and the VC.     

Ultrastructural cytochemistry of the secretory granules of the hamster submandibular gland

Summary The ultrastructure and cytochemistry of the secretory granules of the male hamster submandibular salivary gland were studied. After fixation in glutaraldehyde followed by osmium tetroxide the granules exhibit a characteristic bipartite substructure, with an electron lucid crescenteric rim and a more dense central core. A differentiation into two regions of the granules could also be visualized in specimens primarily fixed in Millonig's osmium tetroxide or in potassium permanganate. The electron lucid peripheral portion of the membrane bounded secretory granules further displays a strong positive reaction after staining of ultrathin sections with the periodic acid-chromic acid-(PA-CrA)-silver technique. The strong periodate reactivity of the rim relative to the core, suggests a difference in mucin composition of the two granule regions. With the PA-CrA-silver staining technique a positive reaction was also observed within the Golgi apparatus of the acinar cells.     

Inhibition of lactoferrin and vitronectin binding toStaphylococcus aureus by heparin

Cells ofStaphylococcus aureus strain ISP 546, previously shown to express high binding of vitronectin (Vn), were shown also to bind radioactive iodine-labeled human lactoferrin (Lf). The binding was specific, and heat treatment ofS. aureus cells abolished Lf binding. When cells were preincubated with heparin (2.5 g/ml), binding of Vn and Lf was inhibited by more than 90%. Two other sulfated carbohydrate polymers, fucoidan and dextran sulfate (mol weights 5000 and 8000) inhibited binding of both iodine-labeled Vn and Lf by about 75% each. No synergistic inhibitory effect between heparin and fuocidan on Lf binding byS. aureus was detected. Mannose, mannoseamine and poly--sialic acid (colominic acid) inhibited Vn binding by about 40% but had no effect on Lf binding. A cell surface extract of ISP 546 inhibited Vn binding but did not affect Lf binding. Lf binding toS. aureus was inhibited by preincubation of the cells with Vn, and Vn binding toS. aureus was inhibited by preincubation with Lf. Our data indicate that Vn and Lf bind to different molecules on theS. aureus cell surface, involving heparin and other carbohydrate interactions.     

Immunological Recognition of Fibronectin-Binding Proteins of Staphylococcus aureus and Staphylococcus capitis,Strain LK499

Antibodies to fibronectin-binding proteins (FnBPs) of Staphylococcus aureus, including binding domain of FnBPA, the D region, or the A-C regions of FnBPB were produced in rabbits and mice. These antibodies were used to characterize cell-associated FnBPs of S. aureus strain Cowan I, S. aureus strain U320 and a coagulase-negative Staphylococcus capitis strain LK499 as well as extracellular FnBPs in culture supernatants of the strain U320. FnBPs of S. aureus were predominantly FnBPA, while FnBPB was hardly detected on the cells or in culture supernatant of these S. aureus strains. Moreover, S. capitis strain LK499 possessed different FnBP(s) compared to S. aureus because the antibodies to S. aureus FnBPs did not recognize FnBP(s) on S. capitis.     

Combined serum IgG response to Helicobacter pylori VacA and CagA predicts gastric cancer

Helicobacter pylori is a major factor for the development of gastric cancer. The aim of this study was to define serum antibody patterns associated with H. pylori infection in patients with gastric cancer using a Western blot technique. Serum samples collected from 115 patients with gastric cancer and 110 age- and gender-matched patients without gastrointestinal diseases were tested for IgG antibodies to H. pylori antigens (outer membrane proteins and whole cell preparations). No significant differences were found between patients with and without gastric cancer using outer membrane proteins (82% and 73%, P>0.05) or whole cell antigens (84% and 76%, P>0.05), respectively. The significant differences between patients with and without gastric cancer were associated with bands of 94 kDa (54% and 20%, P<0.001) and 30 kDa (65% and 44%, P<0.01). A combination of antibodies to 85 kDa (VacA) and 120 kDa (CagA) was significantly (P<0.01) more frequent in gastric cancer patients than in patients without gastric cancer. The detection of antibodies to 94- and 30-kDa bands, in association with the determination of serum antibodies to CagA+/VacA+, may have a prospective value in assessment of the risk of developing of gastric cancer.     

A collagen binding protein from Lactobacillus reuteri is part of an ABC transporter system?

Abstract The gene coding for a collagen binding protein from Lactobacillus reuteri NCIB 11951 was cloned and sequenced. A genomic lambda library was constructed and recombinant plaques were screened using antisera raised against purified collagen binding proteins from the same L. reuteri strain. The positive plaques were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis, which revealed the expression of a 29 kDa protein, which reacted with the antisera and bound ¹²⁵I-labelled type I collagen. The sequence of the corresponding gene, cnb showed that the collagen binding protein has sequence similarities to the solute binding component of bacterial ABC transporters.     

Lack of evidence for sialidase activity in Helicobacter pylori

The role of sialic acid for the adhesion of Helicobacter pylori to gastric mucosa cells and/or to the mucin layer is still under debate. Several but not all H. pylori strains express a sialic acid-binding adhesin, specific for terminal α-2,3-sialic acid residues. Recently, the production of sialidase by H. pylori was reported [Dwarakanath, A.D. et al. (1995) FEMS Immunol. Med. Microbiol. 12, 213–216]. We analysed several strains isolated from gastric biopsies cultivated both in liquid media and on agar plates for sialidase. Activity of this enzyme was first assayed using the fluorigenic substrate 4-methylumbelliferyl-α-d-N-acetylneuraminic acid. Since the fluorimetric assay can give false-positive results caused by non-specific interactions with umbelliferyl-tagged substances, we used also the more sensitive and specific assay with sialyl-[³H]lactitol as a substrate. No evidence for sialidase activity of H. pylori strains, cultivated under both inducible and non-inducible conditions, was obtained.