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

We have examined the epididymal (caput, corpus and cauda) and ejaculated spermatozoa of bufallo-bull (Bubalus bubalis) employing microscopic and spectroscopic techniques. Fluorescein isothiocyanate conjugated lectins namely concanavalin A (Con A), Dolichos biflorus (DBA), Maclura pomifera (MPA), peanut agglutinin (PNA), soybean agglutinin (SBA) and wheat germ agglutinin (WGA) were used to study the changes in the sperm surface carbohydrate make up as the spermatozoa mature. Quantitative analysis of the lectin binding was made flow cytometrically. 31P-NMR (nuclear magnetic resonance) spectra of the sperms obtained from different regions (head, body and tail) of the epididymis and of the ejaculate were analyzed to assess their metabolic activity. And the kinetics of spin label reduction of these samples was monitored with ESR (electron spin resonance) spectroscopy. These observations are supplemented with the electron microscopic (SEM and TEM) examination of the epididymal and ejaculated spermatozoa.
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PMID:Spectroscopic and microscopic studies of buffalo-bull (Bubalus bubalis) spermatozoa. 838 30

We evaluated two different assays for the determination of bone-specific alkaline phosphatase (B-AP). One assay was a direct method using a two-site IRMA (AP(Hyb)). The other assay determined B-AP indirectly after precipitation with lectin (AP(BM)). The assays were compared to serum osteocalcin (levels) and total AP in 20 premenopausal women and in 40 early postmenopausal women before and after 9 months of treatment with hormone replacement therapy (HRT) (n = 20) or placebo (n = 20). Serum osteocalcin correlated with serum AP(Hyb) (r = 0.45), and with serum AP(BM) (r = 0.33) (both p < 0.001). The correlation between AP(Hyb) and AP(BM) was moderate, r = 0.71 (p < 0.001). When comparing postmenopausal to premenopausal women, serum osteocalcin had a t score (mean +/- SEM) of 2.30 +/- 0.29 followed by total AP(T-AP) (1.20 +/- 0.28), AP(Hyb) (1.05 +/- 0.33) and AP(BM) (0.64 +/- 0.21) (paired t-test: p < 0.01 for osteocalcin vs. other markers). After 9 months of HRT all markers had declined significantly to premenopausal levels (mean +/- SEM): osteocalcin with 44.5% +/- 6.1%; AP(BM) with 32.1% +/- 5.6%; AP(Hyb) with 36.4% +/- 4.4% and T-AP with 24.4% +/- 2.9%; p < 0.001. Of the markers, only serum osteocalcin correlated significantly with the rate of bone loss in the placebo group (r = 0.52, p < 0.02). We conclude that both assays for B-AP reflect bone turnover in postmenopausal women with and without HRT. Under controlled conditions they did not show any advantage of osteocalcin in diagnosing increased bone turnover or monitoring the effect of an anti-resorptive therapy in postmenopausal women.
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PMID:The effect of menopause and hormone replacement therapy on bone alkaline phosphatase. 863 81

The floc-forming ability of flocculent strains of Kloeckera apiculata, isolated from musts, was tested for susceptibility to proteinase and sugar treatments. Three different flocculation phenotypes were discriminated by protease digestion, whereas the inhibition of flocculation by sugars distinguished two definite patterns: one mechanism of flocculation involved a galactose-specific protein and the other a broad-specificity lectin. SEM and TEM observation of the cell surface of two different Kloeckera strains revealed fine fibrils and a diffuse structure at the point of contact in one strain, and thick masses of mucus on the cell wall of the other strain.
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PMID:The flocculation of wine yeasts: biochemical and morphological characteristics in Kloeckera apiculata. 874 Sep 10

The apical surface of the guinea-pig organ of Corti was examined with SEM after WGA-lectin histochemistry which has a binding specificity for sialic acid and N-acetyl-glucosamine. The contrast of colloidal gold markers were particularly enhanced by back-scattered electron imaging. WGA lectin showed remarkable preference for the microvilli as well as flat surface areas in the supporting cells. Stereociliary surfaces and interstereociliary connections of the sensory hair cell were strongly labelled, whilst only rarely the markers were found in the flat areas of the apical surface of the hair cell. The connections, which are known to be involved in the initiation of the mechanoelectrical transduction, should consist of sialic acid and/or N-acetyl-glucosamine.
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PMID:WGA lectin binding sites of the apical surface of corti epithelium: enhancement by back-scattered electron imaging in guinea-pig inner ear. 876 16

Ricin, a toxic lectin from the castor bean, affects the cardiovascular system. Because calcium is very important in cardiotoxicity and cell intoxication, we studied the effects of ricin pretreatment to rabbits on basal intracellular calcium levels and calcium uptake and release from isolated papillary muscle, microsomes, and mitochondria. An increase in basal intracellular calcium levels was observed. Ricin pretreatment nearly doubled the intracellular-free Ca2+ concentration as measured by fura-2 fluorescence microscopy in isolated myocytes (p = 0.002). Ricin did not alter basal calcium efflux in isolated papillary muscles. However, ricin inhibited the NE-induced calcium efflux (expressed as fractional efflux ratios) in papillary muscles from rabbits receiving the minimum lethal dose of ricin at 25-35 minutes (p = 0.002 and 0.003, respectively). Ricin depressed basal calcium uptake into isolated papillary muscles at 5 minutes (mean +/- SEM, mumol/g wet weight) (control: 3.68 +/- 0.57; ricin: 2.31 +/- 0.28, p = 0.045, n = 6). Ricin pretreatment significantly depressed calcium uptake into microsomes (mean +/- SEM, mumol/g protein) (control: 9.9 +/- 1.9; ricin: 3.1 +/- 1.9, p = 0.025, n = 6). Calcium uptake into mitochondria was increased at the beginning (2 minutes, p = 0.048), but not thereafter. Thus, administration of ricin disturbed calcium homeostasis in the rabbit heart, which may be at least partially responsible for altering cardiac function and myocardial cell death.
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PMID:Ricin disturbs calcium homeostasis in the rabbit heart. 893 35

Serum neuraminidase (NA, sialidase) activity has been demonstrated in acute poststreptococcal glomerulonephritis (APSGN) and implicated in the pathogenesis of the disease. Recent investigations show that neuraminidase-treated leukocytes accumulate preferentially in kidneys; therefore, we were interested in knowing if desialized cells infiltrate the kidney in APSGN. We first tested the capacity of peanut agglutinin lectin (PNA) to detect injected NA-treated leukocytes in the kidney of rats. NA-treated leukocytes were transfused and desialized cells were identified with fluorescein-conjugated peanut lectin (FITC-PNA) in renal tissue. PNA positive cells were identified in rat kidneys 3 hours after injection (glomeruli: 1.67 +/- 0.19 cells/g.c.s.; interstitium: 0.50 +/- 0.12 cells/int). Sections from available renal biopsy material of APSGN (n = 11), other glomerulonephritis (n = 28) and normal kidneys (n = 5) were double-stained with FITC-PNA and with monoclonal antibody to the CD11b molecule, which is expressed on polymorphonuclear and monocytes the main types of infiltrating cells during APSGN. Desialized (FITC-PNA positive) cells were found in the glomeruli (2.17 +/- SEM 0.22 cells per glomerular cross section, g.c.s.) and interstitium (0.61 +/- 0.15 cells per 0.0625 mm2, int) in all biopsies of APSGN. Only in 2 of 28 other glomerulonephritis showed desialized cells. More than 80% of the PNA positive cells in APSGN expressed the CD11b molecule and the infiltration was more intense in early biopsies. In conclusion, desialized leukocytes represent a significant part of the inflammatory infiltrate in APSGN. This finding gives support for a role of NA in the disease and provides clinical validation for a mechanism of renal cellular infiltration suggested by experimental observations.
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PMID:Histological evidence of neuraminidase involvement in acute nephritis: desialized leukocytes infiltrate the kidney in acute post-streptococcal glomerulonephritis. 912 87

Eggs of the marine gastropod Crepidula fornicata examined by confocal imaging of FITC-lectin binding to the surface, and cryoscopic-SEM both reveal a surface architecture of linear structures organized around the animal-vegetal axis, which is spatially related to the anterior-posterior (a-p) axis of the subsequent embryo. A series of structures is also orientated with reference to specific micromere quartets formed during spiral cleavage. Thus, the surface architecture may provide a visible marker for a morphogenetic field which generates the a-p axis and organizes the cleavage pattern. Moreover, this architecture is co-extensive with that found on the vegetal, polar lobe-bearing region of eggs, as described by others, and which varies between gastropod taxa with varied types of body form. Confocal imaging reveals a distinct localization of F-actin to the architecture of the lobe region. However, the integrity of this F-actin is not responsible for the maintenance of the surface architecture. The significance of these findings to our understanding of the generation of diversity within the Gastropoda and general ontogenic mechanisms is discussed.
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PMID:Morphological evidence for a morphogenetic field in gastropod mollusc eggs. 949 89

Lectins or agglutinins are proteins with affinity for specific sugar residues. Peanut agglutinin (PNA) and the lectin from the edible mushroom (Agaricus bisporus, ABL) both bind to the disaccharide galactosyl beta-1,3-N-acetyl galactosamine alpha-. This is expressed in keratinocytes as an O-linked chain on CD44, a polymorphic membrane glycoprotein. Many lectins are mitogens and PNA is a mitogen for colonic epithelial cells. However, ABL reversibly inhibits proliferation of colonic cancer cell lines without cytotoxicity and thus has therapeutic potential in situations such as psoriasis where proliferation is increased. We have therefore investigated the effect of ABL on the growth of normal human cultured keratinocytes and a human papilloma virus (HPV)-transformed cell line. In a 5-day dose-response study, keratinocyte growth was greatly reduced by 1.0 microg/mL ABL and completely inhibited by 3.0 microg/mL ABL (ANOVA, P < 0.0001). Exposure to 1.0 microg/mL ABL for only 8 h gave the same growth inhibition as did continued exposure for 3 days. No cytotoxic or morphological changes were observed. An HPV-immortalized cell line was relatively resistant to ABL: in a 5-day dose-response study, exposure to 30 microg/mL was required to inhibit cell growth completely. Topical application of ABL 0.01% or 0.1% to normal human skin caused no change in skin erythema, blood flow or thickness compared with vehicle or baseline (n = 6). ABL 0. 1% in white soft paraffin was compared with vehicle in 11 psoriatic patients, using comparative contralateral plaques. Twice daily application for 2 weeks showed no significant difference from vehicle-treated sites, although the skin thickness of plaques fell from 5.3 +/- 0.4 (n = 11, mean +/- SEM) to 4.1 +/- 0.3 mm. In view of the in vitro results further studies are warranted, particularly if means can be found to improve the epidermal penetration of the relatively large ABL molecule (60 kDa).
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PMID:The antiproliferative effect of lectin from the edible mushroom (Agaricus bisporus) on human keratinocytes: preliminary studies on its use in psoriasis. 1021 68

The microenvironment near the apical membrane of MDCK cells was studied by quantitation of the fluorescence of wheat germ agglutinin attached to fluorescein (WGA). WGA was shown to bind to sialic acid residues attached to galactose at the alpha-2,3 position in the glycocalyx on the apical membrane. Young MDCK cells (5-8 days after splitting) showed a patchy distribution of WGA at stable sites that returned to the same locations after removal of sialic acid residues by neuraminidase treatment. Other lectins also showed stable binding to patches on the apical membrane of young cells. The ratio of WGA fluorescence emission at two excitation wavelengths was used to measure near-membrane pH. The near-membrane pH was markedly acidic to the pH 7.4 bathing solution in both young and older cells (13-21 days after splitting). Patches on the apical membrane of young cells exhibited a range of near-membrane pH values with a mean +/- SEM of 6.86 +/- 0.04 (n = 121) while the near-membrane pH of older cells was 6.61 +/- 0.04 (n = 120) with a uniform WGA distribution. We conclude that the distribution of lectin binding sites in young cells reflects the underlying nonrandom location of membrane proteins in the apical membrane and that nonuniformities in the pH of patches may indicate regional differences in membrane acid-base transport as well as in the location of charged sugars in the glycocalyx.
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PMID:The apical membrane glycocalyx of MDCK cells. 1088 25

The study reports on secretion production and composition in the tubular glands of the canine anal sacs. For this purpose, light and electron microscopical (TEM, SEM) as well as several histochemical methods for the demonstration of lysosomal acidity, lipofuscin, and complex carbohydrates were used. The glandular tubules exhibited a pseudostratified epithelium with secretory cells of a different shape as related to secretion production activity, and regionally varying amounts of basal cells. Flat, cuboidal or columnar cells with or without apocrine-like protrusions were assembled in one glandular endpiece, although grouping of these cell types often occurred. Active secretory cells were columnar with many cytoplasmic vesicles and a typically merocrine and/or micro-apocrine exocytosis of vesicle contents. Additionally, many lysosomes of different sizes could be found, whereby in aged cells giant secondary lysosomes (autophagolysosomes, about 7 microm in diameter) occupied the major cell part. These giant lysosomes were shed by an apocrine-like process forming a final bottleneck stage of the upper cell part, and consisted of ceroid-type lipofuscin. The general carbohydrate histochemical and the lectin histochemical methods revealed that the secretion produced was composed of strongly concentrated neutral glycoproteins with the following saccharide residues: alpha-D-mannose, beta-D-galactose, beta-N-acetyl-D-glucosamine, alpha-L-fucose and N-acetyl-neuraminic acid (sialic acid); the luminal secretion contained only beta-D-galactose and, especially, N-acetyl-neuraminic acid. This luminal secretion showed a spatially orientated maturation beginning in terminal tubular regions and finishing near the excretory duct, independent of the different secretory cell types. The results obtained demonstrated highly active secretion production, with a regional variation in the glandular tubule, and at least three different modes of secretion by the secretory cells, whereby the shedding of giant lipofuscin granules seems to be very specific. The high amounts of sialic acids in the glycoproteins found may influence the rheological properties of the secretion by their water-binding capacities.
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PMID:Cytological and lectin histochemical characterization of secretion production and secretion composition in the tubular glands of the canine anal sacs. 1117 5


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