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At least 451 records · Page 25Linked to original sources
PubMed1989

The endometrial cycle: the expression of a secretory component correlated with the luteinizing hormone peak.

This paper reports the pattern of production and secretion of a secretory phase epitope in the endometrium of 44 normal fertile women. Peroxidase immunochemistry was used to detect the monoclonal antibody D9B1, which binds to a peptide-associated sialylated oligosaccharide, in endometrial biopsies all chronologically dated from the luteinizing hormone (LH) peak. During the proliferative phase, the epitope was shown to be absent from tissue sections. It first made its appearance within gland cells 2 days after the LH peak. By LH+3 a rapid accumulation of the D9B1 epitope was noted in the base of the cell, below the nucleus. On subsequent days, increasing amounts of the antigen were detected in the apical cytoplasm, apparently in a more concentrated form than in the basal cell zone. On day LH+6, around the time of implantation, secretory vesicles in the cell apex were discharged into the gland lumen where the glycoconjugate finally accumulated. This immunohistochemical approach introduces a new parameter for evaluation of endometrial function and could be used to improve the accuracy of histological assessment of the endometrial cycle.

Adolescent↗
PubMed1995

Morphological and morphometric study of atrial specific granules and other secretory components in dogs experimentally infected with Trypanosoma cruzi.

Changes in blood volume can induce morphometric and morphological alterations in the secretory complex of the myoendocrine cells due to the stretching of atrial walls. These alterations were studied by electron microscopy, using dogs infected intraperitonially with Trypanosoma cruzi and necropsied during the acute phase of the infection when congestive heart failure was present. Several changes were observed in the myoendocrine cells of the heart: hypertrophy and hyperplasia of rough endoplasmic reticulum and Golgi complex, increase in telenuclear secretory complex, increase in fusion of type B atrial specific granules (ASG), decrease of the total number of ASG, enlargement of the maximum diameter of type A ASG and a relative increase in the number of type B ASG. These alterations suggest a larger secretory activity of the atrial myoendocrine cells with a larger secretion of atrial natriuretic peptide (ANP).

Acute Disease↗
PubMed1986

Lectin binding sites in Paramecium tetraurelia cells. I. Labeling analysis predominantly of secretory components.

Though all three lectins tested (ConA, RCA II, WGA) bound to the entire cell membrane, none bound selectively to the docking site of secretory organelles (trichocysts); the same results were achieved with FITC-conjugates, or, on the EM level, with peroxidase- or gold-labeling. Only WGA triggered the release of trichocysts and none of the lectins tested inhibited AED-induced synchronous exocytosis. When exocytosis was triggered synchronously in the presence of any of these three lectins (FITC-conjugates), the resulting ghosts trapped the FITC-lectins and the cell surface was immediately afterwards studded with regularly spaced dots (corresponding to the ghosts located on the regularly spaced exocytosis sites). These disappeared within about 10 min from the cell surface (thus reflecting ghost internalization with a half life of 3 min) and fluorescent label was then found in approximately 6-10 vacuoles, which are several microns in diameter, stain for acid phosphatase and, on the EM level, contain numerous membrane fragments (otherwise not found in this form in digesting vacuoles). We conclude that synchronous massive exocytosis involves lysosomal breakdown rather than reutilization of internalized trichocyst membranes and that these contain lectin binding sites (given the fact free fluorescent probes did not efficiently stain ghosts). Trichocyst contents were analyzed for their lectin binding capacity in situ and on polyacrylamide gels. RCA II yielded intense staining (particularly of "tips"), while ConA (fluorescence concentrated over "bodies") and WGA yielded less staining of trichocyst contents on the light and electron microscopic level. Only ConA- and WGA-staining was inhibitable by an excess of specific sugars, while RCA II binding was not. ConA binding was also confirmed on polyacrylamide gels which also allowed us to assess the rather low degree of glycosylation (approximately 1% by comparison with known glycoprotein standards) of the main trichocyst proteins contained in their expandable "matrix". Since RCA II binding could be due to its own glycosylation residues we looked for an endogenous lectin. The conjecture was substantiated by the binding of FITC-lactose-albumin (inhibitable by a mixture of glucose-galactose). This preliminary new finding may be important for the elucidation of trichocyst function.

Animals↗
PubMed2002

Lectin-blot analyses of Trichinella spiralis muscle larvae excretory-secretory components.

The rapid recognition of invading pathogen polysaccharides by host lectins might have a significant role in the outcome of the infection. Oligosaccharide structures of the pathogens may provoke an antibody response and serve as a target for specific antibodies. It is well known that Trichinella spiralis antigens, either on the surface or excreted-secreted, are key modulators or targets of the host immune system. In our study of the role of lectins in host defense against T. spiralis infection, an investigation on sugar component of parasite glycoproteins was performed. Affino-blot analyses of T. spiralis muscle larvae excretory-secretory (ES) products by plant lectins revealed that these proteins possess: (1) N-glycans (ConA, PSA, PHA), and probably some O-linked structures (AAA), (2) oligosaccharide structures with mannose residues, especially of the oligomannose type (ConA) and the biantennary complex type with Fuc in the pentasaccharide core (PSA), (3) bisected oligosaccharides, probably some polyantennary glycophorms (PHA), (4) terminally positioned Gal (RCA I, AAA), (5) N-glycans containing oligomers of, or bisected GlcNAc (WGA), that lack alpha2,6 type of linkage (absence of SNA binding).

Animals↗
PubMed1996

The time course of ultrastructural changes in the secretory components of pancreatic acinar cells and trypsinogen activation in taurocholate pancreatitis in rats.

The purpose of this study was to compare a time course of ultrastructural changes of secretory compartment of acinar cells in the pancreas, and a pattern of trypsinogen activation during the course of taurocholate acute pancreatitis (AP) in rats. Acute pancreatitis was induced in 21 rats by injection 0.2 ml of 5% natrium taurocholate into the biliopancreatic duct. Control rats (n = 18) were sham operated (SO). The ultrastructural and biochemical (trypsinogen activation, free active [FAT] and total potential trypsin [TPT]) examinations were performed after 6, 12 and 18 h of AP or SO. Ultrastructural lesions of acinar cells comprised of disorganization of RER, enlargement of Golgi apparatus, changes in size, shape and number of zymogen granules. These alterations were most conspicuous after 6 h of AP and they were associated with maximal activation of trypsinogen. Biochemical changes gradually normalized at 12 to 18 h of AP, however the morphological lesions persisted at these intervals of time.

Acute Disease↗
PubMed1996

MUC1 as a cell surface and secretory component of endometrial epithelium: reduced levels in recurrent miscarriage.

The mucin MUC1 is a large, highly glycosylated, hormonally regulated product of endometrial glandular and luminal epithelium with both cell surface-associated and secreted isoforms. The abundance of mRNA coding for MUC1 increases about sixfold from the proliferative to the early secretory phase (Hey et al., J. Clin. Endocrinol. Metab. 78:337-342, 1994). Immunohistochemical studies show intracellular deposits accumulating in the early secretory phase followed by the release of MUC1 into gland lumens. The apical surface of luminal epithelium is strongly immunopositive in the early secretory phase. We have used a two site ELISA to measure MUC1 in uterine flushings as a function of time after the luteinising hormone (LH) peak. Low levels of secretory MUC1 are observed before day LH+7, while values on days LH+7-LH+13 are much higher. Using semi-quantitative immunohistochemical methods we have shown that in women suffering recurrent spontaneous miscarriage, mid secretory phase levels of MUC1 core protein and mucin-associated glycans are reduced (Serle et al., Fertil. Steril. 62:989-996, 1994). Similarly, lower core protein levels are observed in uterine flushings after day LH+7 in these women. Reduced epithelial secretory function and a resultant change in uterine fluid composition are features of endometrium from recurrent miscarriage patients.

Abortion, Habitual↗
PubMed1985

Evidence for a secretory component in the handling of unconjugated bilirubin by the isolated perfused rat kidney.

Previous studies in rats have suggested that the urinary excretion of unconjugated bilirubin (UB) comprises only a small fraction of the pigment that reaches the tubular lumen by glomerular filtration and escapes from tubular cell reabsorption. However, additional data also indicated that UB interacts with renal peritubular cell membranes impairing the secretion of p-aminohippurate (PAH). In this study we examined the possibility of a secretory step which could also be involved in the renal excretory mechanism for UB. An isolated rat kidney preparation was used, and the uptake of UB by renal tissue, the UB appearance in the urine, and the secretion of PAH were analyzed throughout the perfusion. The results indicated that the UB urinary excretion rate changed independently of UB filtered load. The latter remained almost unchanged during the perfusion, whereas the excretion rate of UB and the UB-to-creatinine (Cr) clearance ratio increased significantly. Furthermore, a relationship between the uptake of UB by the kidney, the UB-to-Cr clearance ratio, and the decrease in PAH secretion rate, was proved. In addition, when probenecid was added to the perfusate solution the cumulative uptake of UB by the kidney and the rate of excretion of UB in the urine were diminished. We conclude that the mechanism of UB excretion by the kidney may be considered as the result of a process involving glomerular filtration plus tubular secretion followed by a back diffusion step from the lumen in a similar way to other endogenous compounds, thus explaining the virtual absence of UB from the normal urine.

Animals↗
PubMed2000

The F-actin cytoskeleton modulates slow secretory components rather than readily releasable vesicle pools in bovine chromaffin cells.

Adrenal chromaffin cells were used to test the role of the peripheral cytoskeleton of F-actin in controlling different vesicle pools. Phorbol 12-myristate 13-acetate and calyculin A, two substances affecting phosphorylation-dephosphorylation cycles, produced different degrees of F-actin reorganization, inducing the partial and the almost total disassembly of this structure, respectively, as visualized using rhodamine-phalloidin staining. Consequently, electron microscopy studies revealed the higher efficiency of calyculin-A over phorbol 12-myristate 13-acetate in promoting vesicle access to the plasmalemma boundary. Surprisingly, only the phorbol ester enhanced fast kinetics and the population of rapidly releasable vesicle pools as studied by single-cell amperometry, whereas both agents, as well as the F-actin severing compound, Latrunculin A, promoted an increase in the population of vesicles recruited in response to prolonged or repetitive stimulations. Taken together, our data support the notion that the F-actin peripheral barrier controls primary granule recruitment from reserve vesicle pools, whereas the phorbol ester effect on the rapidly releasable pools might be related to the alteration of late secretory stage through protein kinase C-dependent phosphorylation of an unidentified target.

Actins↗
PubMed1986

Lectin binding sites in Paramecium tetraurelia cells. II. Labeling analysis predominantly of non-secretory components.

All the lectin-FITC conjugates tested (ConA, RCA II, WGA) bind to the surface of Paramecium cells. Yet only WGA yields a distinct fluorescent pattern; it contours the basis of cilia and in some cells it brilliantly stains a few neighbouring rows of the regular surface fields in the anterioventral region (a region known to contain extensive fields of linear aggregates of freeze-fracture particles and to be engaged in conjugation). Incubation in vivo with WGA-FITC resulted in the selective labeling of the cytopharyngeal region as well as of the cytoproct. On Lowicryl K4M sections, WGA-gold probes concomitantly labeled disk-shaped vesicles that are assumed in the literature to serve as shuttle vesicles between these two cell regions and, thus, to connect forming and defecating digesting vacuoles (stages DV I and DV IV). On K4M sections WGA-Au stains also most other components of the lysosomal system. Also on K4M sections RCA II-Au labeled the walls of bacteria contained in DV I and II type digesting vacuoles (but not lysosomes identified bona fide by their size and shape and by their frequent vicinity to or continuity with digesting vacuoles). The WGA data largely support previous conclusions on the possible functional connection of all these elements (DV I-IV, smaller lysosomes, disk-shaped vesicles etc.) of the lysosomal system in Paramecium, as proposed by Allen and his group on the basis of other lines of evidence. As shown in the accompanying paper, ConA-FITC stained ghosts (formed after massive trichocyst exocytosis) also abut into DV-like structures. The different results obtained with the three lectins tested reflect the complex sorting machinery contained in the elaborate lysosomal system of a Paramecium cell. In the cytosol, finally, there occurs a particularly intense staining with ConA-gold, applied to Lowicryl sections, that probably represents glycogen-like particles. The same procedure reveals some weak staining of secretory contents and of nuclear structures.

Animals↗
PubMed1999

Reduced amount of secretory component of IgA secretion in tears of patients with atopic dermatitis.

Coupled with the previous finding that sIgA excretion was reduced onto the surface of the skin, we demonstrated that sIgA secretion in the tears of patients with atopic dermatitis (AD) was significantly lower than that of normal subjects, using a small stick made of nitrocellulose membrane. In the bacterial cultures, we have also detected a higher frequency of Staphylococcus aureus in the tears from patients with AD compared to normal subjects. These findings suggested reduced sIgA secretion on the mucous membrane might play a crucial role in the pathomechanisms of the ocular lesions, such as abnormal bacterial flora and ocular complications as well as the establishment of skin lesions in AD.

Adolescent↗