Pancreatic acinar and islet cells in coculture: selectivity of non-B endocrine cells.
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APUD Cells↗
Biomedical subjects
M Bendayan
Publications and source records attributed to M Bendayan.
Development of the endocrine cells in the rat pancreatic and bile duct system.
Morphological features of the endocrine cells in the duct system of the pancreas and the biliary tract have been recently characterized in the adult animal with respect to their physiological roles. In the present study, we have investigated their chronological appearance as well as their developmental progress at various stages of the rat fetal and postnatal life. On day 12 of gestation, glucagon and insulin, as well as CCK cells, were identified in the pancreatic primordium. On day 14, glucagon and CCK cells were first detected in the epithelial lining of the common hepatic and the hepatic ducts. These cells remained the dominant endocrine type in the duct system during the fetal period. Insulin and pancreatic polypeptide cells were first observed in the common hepatic duct only on days 16 and 18 of gestation respectively. In spite of their presence in the islets, somatostatin cells were not detected in the duct system during fetal life. They started to appear in the accessory pancreatic duct of the neonate, and subsequently in the common hepatic duct as well as in the small pancreatic ones on day 7 after birth. During postnatal development, the endocrine cells showed progressive or retrogressive changes in different portions of the duct system according to the cell type. In general, somatostatin, CCK and pancreatic polypeptide cells showed an increase, while glucagon and insulin cells gradually dwindled in number up to the adult stage. Somatostatin cells exhibited a significant increase in number, becoming the highest population among the duct endocrine cells in the adult. Throughout the developmental progress, the endocrine cells appear to be allocated in regions relevant to their possible influence modulating the exocrine secretion as well as the drainage of the pancreatic and bile fluid.
Aging↗
Differentiation of pancreatic acinar cells into duct-like cells in vitro.
BACKGROUND: Previous studies have shown that a combination of both the extracellular matrix and secretagogues plays critical roles in the maintenance of well-differentiated pancreatic acinar cells in culture. In the present study, we have shown that, upon proper stimulation, acinar cells change their growth pattern and morphologic appearance to a duct like phenotype. EXPERIMENTAL DESIGN: Both rat and guinea pig acinar cells were cultured on or embedded into the Matrigel basement membrane, in the presence of differentiating agents such as dimethylsulfoxide (DMSO), hexamethyl-bis-acetamide, dimethylformamide, triiodothyronine, and butyric acid. The growth patterns, cell proliferation, ultrastructural appearance, intracellular contents, secretion and immunolocalization of amylase, as well as the expression of the ductal marker carbonic anhydrase II and lectin-binding specific sites were analyzed. Moreover, the effects of metabolic inhibitors such as cycloheximide and actinomycin D on the DMSO induced action were also examined. RESULTS: Isolated acinar cells from both rat and guinea pig pancreas showed an important modification of their growth pattern and morphologic appearance when culture embedded into Matrigel in the presence of 2% DMSO. They reaggregate and form isolated branched tubular structures lined by a single cell layer. These tubules can be maintained in culture for over a period of 21 days. The cells lining the tubules were originally acinar cells that became elongated and progressively lost their secretory granules. They displayed a lower number of apical microvilli and established long junctional complexes with elaborated interdigitations. The immunocytochemical localization and biochemical determination of intracellular and secreted amylase revealed a progressive decrease reaching minimal values by the 12th day of culture. The cells further expressed the duct cell marker carbonic anhydrase II and lost the Helix pomatia lectin-binding affinity characteristic of acinar cells. Cell proliferation by modified cells as measured by thymidine incorporation and the autoradiographic labeling index, was significantly lower than in control cultured acinar cells. The DMSO differentiating action was mimicked, but to a lesser extent, by the other agents except butyric acid. Since cycloheximide and actinomycin D inhibited the DMSO-induced changes, protein synthesis and DNA transcription seem to be required. CONCLUSIONS: Our results demonstrate that normal pancreatic acinar cells retain a morphogenetic plasticity and, upon particular stimulation, can change their differentiation commitment pattern toward that of the duct cell phenotype.
3,4-Methylenedioxyamphetamine↗
Ultrastructural localization of DNA in immune deposits of human lupus nephritis.
DNA molecules were revealed in the glomerular wall of lupus nephritis patients by applying two specific colloidal gold cytochemical approaches at the electron microscope level: immunocytochemistry using a monoclonal anti-DNA antibody in conjunction with protein A-gold and enzyme-gold cytochemistry using DNAse-gold complexes. Application of both techniques has demonstrated that DNA molecules are preferentially located over the electron-dense deposits found in the glomerular basement membrane and mesangial matrix of SLE patients, as well as over the nuclei. Their distribution within the glomerular wall was correlated with electron-dense immune deposits revealed by anti-light chain antibodies. In normal control kidney, DNA labeling was restricted to the cell nuclei. Several control experiments have demonstrated the high specificity of the results. These data thus suggest a possible role for DNA as an antigenic component in the formation of immune complexes.
Adolescent↗
Poly-L-lysine-gold probe for the detection of anionic sites in normal glomeruli and in idiopathic and experimentally-induced nephrosis. A comparative ultrastructural study.
Anionic sites play a key role in the charge selectivity of glomerular filtration as well as in the maintenance of the structural integrity of the visceral epithelium and podocytes. Alterations in these sites are believed to be a major factor underlying human idiopathic nephrosis and puromycin-nephrosis in the rat. The poly-L-lysine-gold complex was used for the ultrastructural detection of anionic sites in renal glomeruli of patients with idiopathic nephrosis as well as of rats with puromycin-induced nephrosis, allowing for study of the changes occurring in the anionic sites during nephrosis and for the comparison between human disease and this experimental model. In both normal human and rat controls, the probe was detected on epithelial and endothelial cell surfaces and on the glomerular basement membrane, mainly in both laminae rarae. In proteinuric rats, a decrease in labeling intensity was noted on podocyte membranes and in the lamina rara externa, with a corresponding increase in the more central areas of the glomerular basement membrane. These changes were not as evident in proteinuric humans. Furthermore, a reduction in labeling density was noted in the glomerular basement membrane of proteinuric animals, although this could not be substantiated in human tissues. Poly-L-lysine-gold is a useful probe for anionic sites in fixed tissues, and allows for comparison between human disease and its experimental counterpart.
Adolescent↗
Hapten-tagged plasma proteins as immunocytochemical probes for the study of vascular permeability.
Bovine serum albumin and transferrin were covalently coupled with fluorescein isothiocyanate and digoxigenin, respectively, and intravenously co-injected in equal amounts in mouse. The derivation of the two proteins induces minor alterations of their physicochemical properties as well as of their physiological functions. The two tracers were revealed within vascular and extravascular compartments of diaphragm by quantitative postembedding immunocytochemistry, using antibodies against each of the haptens in conjunction with the protein AG-gold complexes. The influence of different fixatives and embedding protocols on the immunodetectability of the hapten-tagged proteins was assessed. Both resist reasonably well to osmication and embedding in Epon. None of the haptens reacted with the heterologous antibody. At 30 minutes after injection, the tracers were detected in blood plasma, interstitium, and endothelial plasmalemmal vesicles. The presence of both proteins within the interendothelial clefts was inconspicuous. The ratios between the labeling densities found over endothelium, interstitial space, and vascular lumen were similar for both tracers. This suggests that the endothelium of mouse diaphragm capillaries might exhibit comparable permeabilities towards serum albumin and transferrin which are similar in size and charge. The study shows that hapten-tagged polypeptides are close to the corresponding native macromolecules, and represent interesting tools for the morphological study of dynamic processes such as transcytosis.
Animals↗
Characterization of the endocrine cells in the pancreatic-bile duct system of the rat.
Six types of endocrine cells showing immunolabelling against gut or pancreatic islet hormones were identified in the pancreatic-bile duct system of the normal adult rat at the light and electron microscopic levels. They were located within the epithelial lining of the duct system from the intercalated portion to its duodenal opening. However, the distribution and frequency of each endocrine cell varied along the length of the duct system. While insulin, glucagon, somatostatin, and pancreatic polypeptide cells were widely distributed along the entire duct system, small numbers of cholecystokinin and serotonin cells were confined to the terminal portion. A considerable number of somatostatin cells were concentrated in gland-like pouches of the terminal portion of the common pancreatic-bile duct. When the accessory pancreatic duct was present, insulin, glucagon, and somatostatin cells were also found in its epithelial lining. Electron microscopically, the specific content of the secretory granules of all endocrine cells was confirmed by immunolabelling or cytochemical staining. Further the characteristics of the secretory granules of each endocrine cell type corresponded to those present in the same kind of endocrine cells in gut or pancreatic islet. The duct endocrine cells displayed a particular ultrastructural appearance. The "open type cells" were highly polarized, with their apical cytoplasmic process reaching the duct lumen, whereas "closed type cells" showed long basal cytoplasmic processes with no connection with the duct lumen. In general, insulin, and somatostatin cells were of the "open type", while no morphological connection with the duct lumen was found for glucagon and pancreatic polypeptide cells. The presence of various duct endocrine cells with their particular ultrastructural appearance implies that they may take part in modulating the function of the duct system.
Animals↗
Endothelial cell protrusions in the rat aortic wall. Immunocytochemical evidence for an alternative transendothelial passage of plasma proteins.
Focal morphological changes in the endothelial lining were observed in the aortic wall of control rats. They consisted of endothelial cytoplasmic projections and vacuolar structures protruding towards the luminal space and containing electron-dense material. Some of these structures were observed to open into the subendothelial space. Endogenous albumin was detected in these compartments by applying protein A-gold immunocytochemistry to thin tissue sections of glutaraldehyde-fixed, Lowicryl-embedded aortic segments. The labelling was mainly distributed along the plasma membrane of the projections as well as over the dense content of the endothelial protrusions. The presence of endogenous albumin in these endothelial structures, together with their opening into the subendothelial space, suggests a role for these structures in an alternative transendothelial transport of albumin.
Animals↗
Immunocytochemical study of glomerular permeability to anionic, neutral and cationic albumins.
The renal handling of albumin of various isoelectric points (pI) was studied in mice by high resolution quantitative immunocytochemistry. Bovine serum albumin (BSA) was tagged with dinitrophenol (DNP) and cationized to pI 6.5 to 7.5 and to pI over 8.5. These tracers, including the anionic BSA-DNP (pI 4.8) were injected in the iliac vein of mice and the post-embedding protein A-gold technique was used with antibodies against DNP to localize the different tracers in renal tissue. Morphometric analysis of the labeling over the glomerular wall has demonstrated variations in its distribution according to the pI of the markers. Anionic and neutral BSA molecules were detected on the endothelial side of the basement membrane, while labeling for cationic BSA was present mainly in the laminae rarae interna and externa known to display fixed polyanionic sites. Neutral and cationic BSA-DNP reached the urinary space and were detected within the endocytotic apparatus of the proximal tubule epithelium. Neutralization of the anionic sites of the basement membrane with cationic BSA resulted in an increase in the permeability towards anionic BSA-DNP. In addition to the demonstration of glomerular permeability properties towards various probes, the present study has demonstrated that dinitrophenylated albumin represents an excellent versatile tool for the quantitative morphological investigation of glomerular permeability.
Albumins↗
Transendothelial transport of serum albumin: a quantitative immunocytochemical study.
The steady-state distribution of endogenous albumin in mouse diaphragm was determined by quantitative postembedding protein A-gold immunocytochemistry using a specific anti-mouse albumin antibody. Labeling density was recorded over vascular lumen, endothelium, junctions, and subendothelial space. At equilibrium, the volume density of interstitial albumin was 18% of that in circulation. Despite this large difference in albumin concentration between capillary lumen and interstitium, plasmalemmal vesicles labeling was uniformly distributed across the endothelial profile. 68% of the junctions displayed labeling for albumin, which was however low and confined to the luminal and abluminal sides. The scarce labeling of the endothelial cell surface did not confirm the fiber matrix theory. The kinetics of albumin transcytosis was evaluated by injecting radioiodinated and DNP-tagged BSA. At 3, 10, 30, and 60 min, and 3, 5, and 24 h circulation time, blood radioactivity was measured and diaphragms were fixed and embedded. Anti-DNP antibodies were used to map the tracer in aforementioned compartments. A linear relationship between blood radioactivity and vascular labeling density was found, with a detection sensitivity approaching 1 gold particle per DNP-BSA molecule. Tracer presence over endothelial vesicles reached rapidly (10 min) a saturation value; initially localized near the luminal front, it evolved towards a uniform distribution across endothelium during the first hour. An hour was also needed to reach the saturation limit within the subendothelial space. Labeling of the junctions increased slowly, out of phase with the inferred transendothelial albumin fluxes. This suggests that they play little, if any, role in albumin transcytosis, which rather seems to proceed through the vesicular way.
Animals↗
Differences in secretory granule content in pancreatic acinar cells from peri-insular and tele-insular regions.
By applying morphometrical and quantitative double immunocytochemical techniques, differences in size and in amylase and chymotrypsinogen contents were found among pancreatic zymogen granules. These differences were present in granules of peri-insular and tele-insular acinar cells, the peri-insular ones displaying higher numbers of granules of smaller sizes. No correlation was found among enzyme contents in individual granules, nor was there a correlation between enzyme content and granule size. The results suggest that each individual secretory granule is formed in an independent way and that each enzyme is processed and packaged into granules independently. The differences among granules may be associated with nonparallel secretion, since this phenomenon has been reported in the intracellular processing of secretory enzymes. This hypothesis, however, remains to be demonstrated.
Amylases↗
Effect of temperature change on the permeability of eel rete capillaries.
The changes in the permeability properties of the rete capillaries of the eel in response to temperature shifts were studied during countercurrent perfusion at constant flow and pressure. Tracers and oxygen were added to the arterial perfusate. From the ratio of end concentrations of arterial to venous capillaries divided by surface area, calculated from rete weight, a value for the ratio of permeability to flow, P/F, with dimensions in centimeters-2 was estimated. Because flow and surface area are constant, this provides an index of how permeability varies with time. A group of paracellular (albumin, sucrose, and sodium) and cellular (antipyrine, water, and oxygen) probes were used. When the temperature of the perfusate was raised abruptly from 25 degrees C to 35 degrees C, P/F values rose continuously and irreversibly from 0.042 +/- 0.009 to 0.281 +/- 0.112 cm-2 (mean +/- SEM) for 125I-albumin, from 0.082 +/- 0.006 to 1.74 +/- 0.070 cm-2 for [14C]sucrose, and from 0.32 +/- 0.06 to 2.78 +/- 0.62 cm-2 for 22Na, whereas they were not modified for [14C]antipyrine, [3H]water, and O2. Gradual increase of temperature was accompanied by a smaller rise in sucrose and sodium permeability and no change in albumin permeability; with decrease, the change was reversible.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Association of secreted insulin with particular domains of the pancreatic B-cell plasma membrane: the actin-rich microvilli.
Association of insulin with the plasma membrane of the pancreatic B-cell was revealed using the high-resolution protein A-gold immunocytochemical approach. The labeling was found to be heterogeneously distributed, the plasma membrane of the actin-rich microvilli being preferentially labeled. Morphometrical evaluation of labeling intensities confirmed the microvilli location of the insulin binding sites. This membrane domain, which also displays the glucose transporter, therefore appears to play important functional roles in the secretory activity of the B-cell. That the autocrine influence insulin exerts on its own secretion is receptor mediated through these insulin binding sites remains, however, to be determined.
Animals↗
Ultrastructural localization of endogenous albumin in human aortic tissue by protein A-gold immunocytochemistry.
The presence of endogenous plasma albumin in human aortas was demonstrated by immunocytochemical procedures. The protein A-gold approach, combining high resolution and specificity, was applied at the light and electron microscope levels to determine the in situ cellular and extracellular localization of albumin on tissue sections derived from normal and atherosclerotic human aortas. The distribution of albumin across the aortic wall interstitium was found to be uneven, with low to moderate staining intensities in the aortic subendothelial space, low intensities in the media, and high intensities around the vasa vasorum in the adventitia. Albumin was associated with collagen fibers as well as with the electron-dense material bordering the elastic laminae in both normal and pathologic tissues. Extracellular multilamellar structures were found to be characteristic of the necrotic areas of atherosclerotic aortas. These structures were intensely labeled for albumin, with the labeling being closely associated with the membranes. Numerous smooth muscle cell-derived and monocyte-derived foam cells were present in pathologic tissues, and some of their lysosomal compartments were labeled for albumin, suggesting an internalization and degradation of interstitial albumin by these cells.
Aged↗
Presence of extrapancreatic islets of Langerhans in the duodenal wall of the rat.
In the present study we report the existence of typical islets of Langerhans in the duodenal wall of the rat. The nature of the cells and of their corresponding secretory granules were assessed by morpho-cytochemical techniques. The insulin cells formed the core of the islets while the glucagon, the somatostatin and the pancreatic polypeptide cells were located at the periphery. These islets were located in the connective tissue between the duodenal crypts and the muscle layer, neighbouring the last portion of the bile duct. The morphological features of these endocrine cells indicate the presence of high secretory activities which may play an important role in the maintenance of glucose homeostasis, particularly during absorption of nutrients.
Animals↗
Contractile proteins in podocytes: immunocytochemical localization of actin and alpha-actinin in normal and nephrotic rat kidneys.
Actin and alpha-actinin immunoreactive sites have been localized at the electron microscope level by the protein A-gold immunocytochemical technique in podocytes of normal and nephrotic rat renal tissues. In normal renal glomeruli, fibrillar networks located in the core of foot processes or bundles of microfilaments interconnecting them were found to be labelled for these two cytoskeletal proteins. On the other hand, in nephrotic renal glomeruli, concomitant with the loss of podocytic foot processes a reorganization of the podocytic cytoskeleton and a concentration of some of its elements into thick uniform bands was observed. Actin and alpha-actinin were revealed in these bands. Control experiments confirmed the specificity of the labelling obtained. Our results suggest that normal podocytes contain an actin-based contractile system that might contribute to the maintenance of the particular cell shape of these cells and that the rearrangement of the podocytic cytoskeleton occurring in the nephrotic syndrome might account for the changes in the foot processes and contribute to the alteration in glomerular function.
Actinin↗
Secretagogue induction of cell differentiation in pancreatic acinar cells in vitro.
The effect of two different types of secretagogues on rat pancreatic acinar cells cultured onto a reconstituted basement membrane was studied. Cells cultured without any secretagogue were able to reaggregate but did not form monolayer patches. Most of them lost their differentiated ultrastructural characteristics but regained their polarity. In contrast, when CCK, caerulein, or carbamylcholine was added to the culture medium cells developed both acini-like structures and cell monolayer patches. The cells retained the differentiated ultrastructural appearance and polarity resembling their in situ morphology. Furthermore, secretagogue-conditioned cells presented higher amylase contents. The use of secretagogue antagonists such as L-364,718 and L-365,260 for caerulein, or atropine and mecamylamine for carbamylcholine, did not profoundly modify the cultures and the morphological effects triggered by the secretagogues alone. However, both CCK antagonists and cholinergic antagonists inhibited to a certain degree the secretory stimulation. Our data support the theory that a major role is played by secretagogues in conjunction with the basement membrane for the maintenance of differentiation in pancreatic acinar cells in vitro which appears to be independent from their secretory effect.
Amylases↗
Effect of clentiazem on lipid profile, lipoprotein composition and aortic fatty streaks in cholesterol-fed rabbits.
Numerous experimental studies have reported that common antihypertensive drugs such as diuretics, beta-blockers, and methyldopa have adverse effects on plasma lipids and lipoproteins. The present study was designed to define the effect of clentiazem (10 mg/kg/day) an antihypertensive drug, on hyperlipidemia in rabbits on a cholesterol-rich diet (1%) for 12 weeks. Compared with controls, clentiazem treated rabbits had lower plasma concentrations of triglycerides (55%), total cholesterol (24%), free cholesterol (27%), esterified cholesterol (23%) and phospholipids (24%). The decrease in cholesterol was accounted for by a reduction of VLDL-cholesterol (13%), IDL-cholesterol (24%) and primarily LDL-cholesterol (45%). Neither HDL-cholesterol nor chemical composition of VLDL, IDL, LDL and HDL was altered. When the aortic atherosclerotic involvement was evaluated by computerized planimetry, a 24% reduction of lesions was noted in clentiazem treated animals (P less than 0.05). Similarly, cholesterol content extracted from aortic wall was decreased. Our data therefore demonstrated that clentiazem is a potential antiatherosclerotic agent capable of decreasing plasma lipids and atherogenic lipoproteins as well as aortic fatty streaks.
Animals↗