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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eggs and adult males and females of Mekong Schistosoma were studied by scanning and transmission electronmicroscopy. The observation of the eggs by the scanning and light microscopy revealed fine shell fenestration and a prominent knoblike spine. There are marked differences between the surface structures of male and female as studied by scanning and transmission electronmicroscopy. The surface of the male schistosome is moderately rough while that of the female is relatively smooth. SEM reveals certain basic features such as spines in the oral sucker, minute spines and folds in the gynecophoral canal of the male, and general features of male and female tegumental surfaces. The observations of the cross sections of adult schistosomes by transmission technique revealed certain features such as spines or ridges, and mucin droplets on the surface, the smooth muscles lining the integument, the mucin-producing cells and numerous lipid droplets in the body of the Schistosoma.
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PMID:Scanning and transmission electronmicroscopy of Mekong Schistosoma eggs and adults. 48 21

The Entamoeba histolytica galactose-binding lectin is a surface glycoprotein composed of 170- and 35-kDa subunits. Inhibition of this lectin with galactose or anti-170 kDa subunit polyclonal antibody blocks amebic adherence to target cells and colonic mucin glycoproteins. We describe the properties of 10 mAb with specificity for the 170-kDa subunit. Based on competitive binding studies, six nonoverlapping antigenic determinants on the lectin were identified. The effect of the mAb on adherence of amebic trophozoites to both Chinese hamster ovary (CHO) cells and human colonic mucins was measured. Antilectin antibodies directed against epitopes 1 and 2 enhanced adherence, with the number of amebae having at least three adherent CHO cells increasing with the addition of epitope 1 mAb from 26 +/- 9 to 88 +/- 2% and the binding of colonic mucins increasing from 34 +/- 1 to 164 +/- 3 pg/10(5) amebae. Antibody-enhanced adherence remained 90 to 100% galactose inhibitable, occurred at 4 degrees C and was not Fc mediated. Univalent Fab fragments of epitope 1 mAb augmented mucin binding by 238% and CHO cell adherence by 338%. The binding of purified lectin to CHO cells was increased from 1.1 +/- 0.1 to 2.4 +/- 0.3 ng/10(3) CHO cells by mAb directed to epitope 1, demonstrating that enhanced adherence was due to direct activation of the lectin. mAb to epitope 3 bound to the lectin only upon its solubilization from the membrane and had no effect on adherence. Adherence to CHO cells and mucins was inhibited from 50 to 75% by mAb to epitopes 4 and 5; epitope 6 mAb inhibited amebic adherence to CHO cells but not mucins. The pooled sera from 10 patients with amebic liver abscess blocked the binding to the 170-kDa subunit of mAb directed to all six epitopes. Striking individual variations in the effects of immune sera on adherence were observed. Although the sera of all 44 South African patients with amebic liver abscess had high titer anti-lectin antibodies, 16 patients' sera significantly (more than 3 SEM) enhanced adherence whereas 25 patients' sera significantly inhibited adherence. Antilectin antibodies exert profound functional effects on the interaction of E. histolytica with target cells and human colonic mucins. Exploration of the clinical consequences of adherence-enhancing and inhibitory antibody responses may give insight into the role of antilectin antibodies in immunity to invasive amebiasis.
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PMID:Monoclonal antibodies directed against the galactose-binding lectin of Entamoeba histolytica enhance adherence. 169 41

The epithelial cell types present in respiratory (= distal alveolarized) and terminal (= distal nonalveolarized) bronchioles in adult human lung were characterized with scanning and transmission electron microscopy (SEM, TEM) and light microscopic cytochemistry, using specific antibodies against surfactant protein SP-A and mucins, and Alcian blue/periodic acid-Schiff (AB/PAS) staining. In the respiratory bronchiole, two epithelial cell populations share the same basal lamina: one pseudostratified columnar with ciliated, secretory, and basal cells and the other predominantly simple cuboid with some interspersed flat (type I) cells. The columnar secretory cells show the ultrastructure of mucous cells. Light microscopically, they react with mucin antibodies and contain primarily periodate-reactive acid mucins. The mucous cells are the distal secretory cells described by Clara (1937). The cuboid cells are identified as type II (precursor) cells based on ultrastructural criteria for embryonic type II cells (Ten Have-Opbroek et al., 1988a, 1990a), including a cuboid cell shape, a large and roundish nucleus, rough and smooth endoplasmic reticulum (ER), osmiophilic multivesicular bodies, and dense bodies. These dense bodies in turn frequently exhibit--like those in embryonic type II cells--internal vesicles or lamellae, variability in size and shape, a specific relationship to ER and a widespread cytoplasmic distribution. Finally, the cuboid cells show a cytoplasmic staining pattern for SP-A. The terminal bronchiole is lined by the columnar cell population. In the respiratory bronchiole, the columnar (bronchial) and cuboid (alveolar) cell populations occupy distinctly different zones (pulmonary artery zone versus remaining wall). The alveolar part of the respiratory bronchiole (called alveolar tubule) defines the proximal border of a true respiratory unit.
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PMID:The proximal border of the human respiratory unit, as shown by scanning and transmission electron microscopy and light microscopical cytochemistry. 170 49

The interaction of lactoferrin (Lf) with Aeromonas hydrophila (n = 28) was tested in a 125I-labeled protein-binding assay. The mean per cent binding values for human Lf (HLf) and bovine Lf (BLf) were 13.4 +/- 2.0 (SEM), and 17.5 +/- 2.7 (SEM), respectively. The Lf binding was characterized in type strain A. hydrophila subsp. hydrophila CCUG 14551. The HLf and BLf binding reached a complete saturation within 2 h. Unlabeled HLf and BLf displaced 125I-HLf binding in a dose-dependent manner, and more effectively by the heterologous (1 microgram for 50% inhibition) than the homologous (10 micrograms for 50% inhibition) ligand. Apo- and holo-forms of HLf and BLf both inhibited more than 80%, while mucin caused approx. 50% inhibition of the HLf binding. Various other proteins (including transferrin) or carbohydrates did not block the binding. Two HLf-binding proteins with an estimated molecular masses of 40 kDa and 30 kDa were identified in a boiled-cell-envelope preparation, while the unboiled cell envelope demonstrated a short-ladder pattern at the top of the separating gel and a second band at approx. 60 kDa position. These data establish a specific interaction of Lf and the Lf-binding proteins seem to be porins in A. hydrophila.
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PMID:Specific binding of lactoferrin to Aeromonas hydrophila. 177 17

Noninvasive break-up time (NIBUT) of the tears was measured in a controlled, randomized, double-masked study to assess: (1) the stability of the prelens tear film during wear of new high and low water content lenses and (2) the stability of the precorneal tear film following lens removal after 1 h of wear. The prelens tear film NIBUT of 6 subjects was found to be relatively constant over a 1-h wearing period, averaging 6.1 +/- 1.1 s (mean +/- SEM). These values were significantly (Scheffe's S test, p less than 0.05) lower than those recorded for the precorneal tear film before lens insertion (33.5 +/- 10.6; mean +/- SEM), although 85% of prelens tear film NIBUT's were greater than the 3-s average interblink period reported previously for soft lens wearers. After lens removal, precorneal tear film NIBUT was reduced significantly compared to prewear levels (Scheffe's S test, p less than 0.05) for up to 15 min. Application of the monomolecular growth model to the NIBUT recovery data revealed a half-time for recovery of 6.0 min, with recovery 95% complete 25.8 min after lens removal. Lens type was not a significant factor in tear film stability, either during wear or after lens removal. The basis for reduced precorneal tear film NIBUT after lens removal is unknown; however, a disruption of the mucin layer coating the corneal epithelium is the most likely mechanism. Indeed, the technique of measuring precorneal tear film NIBUT after lens removal may be a useful determinant of the extent to which contact lens wear disrupts the precorneal mucin layer, providing an indication of the susceptibility of the cornea to a variety of complications.
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PMID:Effect of hydrogel lens wear on tear film stability. 185 1

The pathogenesis of enteric changes was studied in gnotobiotic piglets which, after hysterectomy had been infected orally with Campylobacter jejuni on the first day of their life. The involvement of the entire large intestine became clinically manifest by scouring on days post infection (DPI) 4 to DPI 5, and pathomorphologically, by simultaneous inflammation and severe edema of the intestinal wall. Histology and SEM revealed inflammatory edema with abundant neutrophils, microulcerations, focal propagation and activation of goblet cells, and a presence of mucin-positive material within the intestinal lumen. TEM examination revealed disconnected interdigitating folds and wide dilated intercellular spaces between enterocytes. The endothelial cells of small blood vessels in the lamina propria showed hypertrophy with increase in the thickness of their basal lamina. Ultrastructural lesions of the large intestinal microcirculation also support the hypothesis that disturbances in the vascular system are responsible for edema in the cecum and colon. Gnotobiotic piglets may be used as a suitable animal model to study colitis induced by C. jejuni.
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PMID:The gnotobiotic piglet as a model for the pathogenesis of Campylobacter jejuni infection. 276 93

SEM was used to visualize tear-film/hydrogel polymer surface interactions. Lenses were preserved by fixation including a quaternary ammonium complex to aid in mucin preservation. In less than 2 weeks of continuous wear the anterior surface was completely coated, yet the coating was absent from the posterior lens surface. Tear-film break-up over the deposited lens surface, combined with degradation and deformation at the polymer surface boundary, as well as entrapment of moieties within the polymer matrix, all occurred. These are the likely culprits which can contribute to adverse reactions as well as cause light scatter and diminished vision. Lenses removed directly from the eyes of patients suffering with different forms of conjunctivitis were obtained. Bacterial and viral conjunctivitis can induce a microbially contaminated as well as a heavily deformed and deposited lens. Viable and intact microbes were not typically observed in the mucoprotein layer of hydrogel contact lenses.
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PMID:Surface interactions on hydrogel contact lenses: scanning electron microscopy (SEM). 348 Sep 10

A total of 39 samples of hostile mucus, as defined by postcoital examination, were examined for N-acetylneuraminic acid (NANA) deficiency, as measured by the enzymatic addition of NANA, spermatozoal penetration and immobilization. Only 56.7% of the mucus samples were deficient in NANA and this did not correlate with spermatozoal penetration or immobilization, which were negatively correlated. Thus, as the spermatozoal hostility in the mucus decreases, spermatozoal penetration increases. This finding also applies to hostile mucus not deficient in NANA. In contrast, resialylation of NANA hostile mucus, deficient and not deficient in NANA, although not enhancing spermatozoal penetration, did reduce spermatozoal immobilization. Thus, components of the mucus deficient in NANA and/or the lack of unbound NANA may contribute to mucus hostility, but it is not the only hostile factor. In addition, SEM studies of NANA-deficient mucin before and after resialylation were shown to have similar structures. Hence ultrastructural changes are not apparent in NANA-deficient mucin, and this supports the previous finding that NANA deficiency does not impede spermatozoal penetration. The spermatozoa from the husbands of the infertile couples formed three distinct groups in terms of spermatozoal penetration and immobilization in normal donor mucus. One group demonstrated normal levels of spermatozoal penetration and immobilization in donor mucus. A second group was demonstrable in which spermatozoal penetration was similar to that in the wife's hostile mucus, but had a normal level of spermatozoal immobilization. In the third group, both spermatozoal penetration and immobilization in donor mucus were similar to that in the wife's hostile mucus. The results demonstrate that not all hostile mucus is deficient in NANA, and that other unknown factors are involved. In addition, there are also male factors which may impede spermatozoal penetration and/or result in the inability of the spermatozoa to survive in normal donor mucus.
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PMID:N-acetylneuraminic acid and hostile mucus infertility. 366 64

To explore the time course and the mechanism of development of bronchial secretory cell metaplasia (SCM) induced by human neutrophil elastase (HNE), anesthetized hamsters were injected intratracheally with 300 micrograms highly purified HNE in 0.5 ml saline solution; saline-injected and untreated animals served as controls. At 3, 8, 16, and 21 days after treatment, animals were killed and their lungs fixed by vascular perfusion. Samples from the hilar region of the left lung, containing the main axial airway and its proximal branches, were embedded in Epon-Araldite, and 1 micron sections were stained with methylene blue. Epithelial cells with a luminal border were categorized into three cell types and expressed as a percent of total cells counted (mean 1900 per animal); cells containing at least three mucin granules were classified as secretory, ciliated cells displayed cilia or basal bodies, and cells with none of these characteristics were classified as indeterminate. Percentages of the three cell types in saline-treated animals, at all time points, were comparable to those in the untreated controls. With HNE treatment the secretory cell percentages were higher at 16 days (mean +/- SEM, 36.4% +/- 3.2%) and at 21 days (35.7% +/- 2.9%) than in the untreated animals (18.2% +/- 1.8%, P less than 0.05). The percentage of the indeterminate cells in the HNE group was decreased at days 8, 16, and 21 (7.2% +/- 1.6%, 5.0% +/- 1.4%, and 8.2% +/- 2.5%, respectively) compared with that in the untreated group (21.7% +/- 2.5%, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Quantitative study of secretory cell metaplasia induced by human neutrophil elastase in the large bronchi of hamsters. 384 55

The effects of the undecapeptide, substance P(SP), on the secretion of mucin and proteolytic enzymes from dispersed cells of the rat submandibular gland were studied. The peptide, at a concentration of 1 X 10(-7) M, stimulated the release of 31.9 +/- 3.0% (mean +/- SEM) of intracellular mucin over 40 min, compared with 12.5 +/- 1.5% in untreated controls (p less than 0.01). This effect was duplicated by the homologous peptides, physalaemin, and eledoisin-related peptide. Substance P action was not affected by pre-incubation of cells with phentolamine or propranolol and was therefore independent of adrenergic stimulation. Furthermore, SP did not enhance the intracellular concentrations of cyclic AMP or cyclic GMP, confirming that cyclic nucleotides were not involved in its stimulus-secretion coupling mechanism. The isoproterenol-stimulated secretion of mucin from dispersed cells was reduced to 75.7% of the normal response (p less than 0.01) after a brief exposure to SP. This inhibitory effect was probably mediated by intracellular events rather than by direct effects on cell surface receptors. However, mucin release after treatment with SP followed by norepinephrine (NE) was 161% of that caused by NE alone (p less than 0.01) and may reflect an additive response to the independent stimulation of SP and NE receptors. Substance P and related peptides had no effect on arginine esterase secretion in the experimental model, although a response was elicited by alpha- and beta-adrenergic agonists. It is, therefore, proposed that serous cells of the granular convoluted tubule in the rat submandibular gland lack substance P receptors.
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PMID:Effect of substance P on exocrine secretion by rat submandibular gland cells. 620 29


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