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A R Beaudoin

Publications and source records attributed to A R Beaudoin.

At least 37 records · Page 2Linked to original sources
PubMed1997

Purification, characterization, and localization of two ATP diphosphohydrolase isoforms in bovine heart.

Two ATP diphosphohydrolase (ATPDase) isoforms have been purified from the bovine heart ventricle. The purification procedure includes the following steps: differential centrifugation, sucrose cushion centrifugation, solubilization with Triton X-100, DEAE agarose ion exchange, and Affi-Gel blue-Sepharose and concanavalin A (con A)-Sepharose chromatographies. The purified enzyme has an optimum pH of catalysis of 7.5 and requires Ca2+ or Mg2+. The apparent Michaelis constant of the enzyme, with ADP as the substrate, is 29 microM, and the apparent maximal velocity is 1.6 mumol.min-1.mg protein-1. Substrate specificity, heat-inactivation curves, and copurification of adenosinetriphosphatase (ATPase) and adenosinediphosphatase (ADPase) activities confirmed the identity of the purified enzyme as an ATPDase. In addition, polyacrylamide gel electrophoresis, under nondenaturing conditions, showed identical migration patterns for the protein involved in ATPase and ADPase activities. Western blot analysis, with an antibody that specifically recognizes the NH2-terminal sequence of pig pancreas ATPDase and specifically reacts with bovine and human ATPDases, showed cross-reactivity with the purified ATPDase isoforms from the bovine heart. Immunocytochemical localization in the ventricle produced strong reactions with the plasma membrane of Purkinje fiber cells and the majority of myocardial cells. Immunoreactivity was variable, producing a mosaic-like aspect. As expected, smooth muscle cells and endothelial cells of coronary vessels were highly reactive. This ectoenzyme could play a protective role against the potentially deleterious effects of extracellular ATP. In tandem with 5'-nucleotidase, it produces adenosine, a powerful vasodilator, especially in hypoxic or ischemic conditions that favor the release of ATP.

Animals↗
PubMed1997

Purification and immunohistochemical localization of the ATP diphosphohydrolase in bovine lungs.

We have recently described different isoforms of mammalian ATP diphosphohydrolase (ATPDase; EC 3.6.1.5). In the present study, we purified the lung ATPDase by column chromatographies followed by polyacrylamide gel electrophoresis under nondenaturing conditions. The active polypeptide that has a molecular mass of 78 kDa was identified by affinity labeling to the ATP analog 5'-p-fluorosulfonylbenzoyladenosine (FSBA), followed by detection on Western blot with an antibody specific for FSBA. N-glycosidase F treatment shifted the molecular mass of the 78-kDa polypeptide down to 54 kDa, indicating that the enzyme bears approximately 6-12 NH2-linked oligosaccharide chains. A polyclonal antibody raised against the pancreas ATPDase, which specifically recognized the 78-kDa glycoprotein on Western blot, was used to carry out an immunological survey of the enzyme distribution in bovine lungs. Immunoreactivity was detected on airway epithelia from the trachea down to alveolar cells, airway and vascular smooth muscle cells, submucous glands, chondrocytes, leucocytes, as well as endothelial and mesothelial cells. Such a wide distribution suggests that the ATPDase may affect a variety of physiological effects mediated by extracellular nucleotides, such as airway smooth muscle tone, surfactant secretion, platelet aggregation, and inflammation.

Adenosine↗
PubMed1996

Identification and characterization of CD39/vascular ATP diphosphohydrolase.

Vascular ATP diphosphohydrolase (ATPDase) is a plasma membrane-bound enzyme that hydrolyses extracellular ATP and ADP to AMP. Analysis of amino acid sequences available from various mammalian and avian ATPDases revealed their close homology with CD39, a putative B-cell activation marker. We, therefore, isolated CD39 cDNA from human endothelial cells and expressed this in COS-7 cells. CD39 was found to have both immunological identity to, and functional characteristics of, the vascular ATPDase. We also demonstrated that ATPDase could inhibit platelet aggregation in response to ADP, collagen, and thrombin, and that this activity in transfected COS-7 cells was lost following exposure to oxidative stress. ATPDase mRNA was present in human placenta, lung, skeletal muscle, kidney, and heart and was not detected in brain. Multiple RNA bands were detected with the CD39 cDNA probe that most probably represent different splicing products. Finally, we identified an unique conserved motif, DLGGASTQ, that could be crucial for nucleotide binding, activity, and/or structure of ATPDase. Because ATPDase activity is lost with endothelial cell activation, overexpression of the functional enzyme, or a truncated mutant thereof, may prevent platelet activation associated with vascular inflammation.

Adenosine Triphosphatases↗
PubMed1996

Hydrolysis of P2-purinoceptor agonists by a purified ectonucleotidase from the bovine aorta, the ATP-diphosphohydrolase.

Pharmacologists are becoming more and more aware of the possibility that certain ATP analogues currently used to classify the P2-purinoceptors are dephosphorylated by ectonucleotidases. In this study, we provide evidence that in the vascular system, these purine analogues are hydrolysed by an ATP-diphosphohydrolase (ATPDase). This enzyme is known as the major plasma membrane nucleotidase of endothelial and smooth muscle cells, and is believed to dephosphorylate extracellular triphospho- and diphosphonucleosides. Assays were conducted with a purified ATPDase from smooth muscle cells of bovine aorta. At a concentration of 250 microM, adenosine 5'-(alpha,beta-methylene) triphosphonate (alpha,beta-metATP), adenosine 5'-(beta,gamma-methylene) triphosphonate (beta,gamma-metATP), adenosine 5'-(alpha,beta-methylene) disphosphonate (alpha,beta-metADP), adenylyl 5'-(beta,gamma-imido) diphosphonate (beta,gamma-imidoATP) and adenosine 5'-O-(2-thiodiphosphate) (ADP beta S) all resisted dephosphorylation, whereas 2-chloroadenosine triphosphate (2-chloroATP), 2-methylthioadenosine triphosphate (2-MeSATP) and 8-bromoadenosine triphosphate (8-bromo-ATP) were hydrolysed at 99, 63, and 20% of the rate of ATP hydrolysis, respectively. All the non-hydrolysable analogues tested, except alpha,beta-metADP, competed with ATP and ADP for the ATPDase catalytic site, reducing their hydrolysis by 35-50%. Apparent Km values for ATP and ADP were estimated at 14.1 and 12.0 microM, respectively, whereas apparent Km and Ki values for the purine analogues ranged from 12 to 28 microM. These results strongly support the view that (1) the ATPDase is expected to reduce substantially the P2-response induced by ATP, ADP, and some hydrolysable agonists; and (2) by competing with the hydrolysis of endogenously released ATP and ADP, non-hydrolysable analogues could alter the amplitude or direction of the cellular response induced by these natural substrates.

Adenosine Diphosphate↗
PubMed1996

Control of gamma-glutamyl transpeptidase expression by glucocorticoids in the rat pancreas. Correlation with granule formation.

Glucocorticoids are known to promote the formation of zymogen granules in acinar cells of the exocrine pancreas in vivo as well as in vitro. To gain insight into the mechanism of this regulation, we studied the effects of glucocorticoids on the synthesis of two components of the secretory granule membrane, the glycoprotein 2 (GP-2) and the gamma-glutamyl transpeptidase (GGT). It was demonstrated that following adrenalectomy, degranulation of pancreatic acinar cells is accompanied by a sharp decrease in GGT and GP-2 synthesis as measured by mRNA and protein accumulation. The decline of GGT synthesis was prevented by glucocorticoid replacement therapy, whereas GP-2 synthesis could be maintained with either glucocorticoid or estradiol treatment. These in vivo observations were corroborated and extended in an in vitro study using AR42J pancreatic cells. With this cell line, it was demonstrated that dexamethasone induces the formation of zymogen granules and the accumulation of a specific GGT transcript (mRNA III) by decreasing its degradation rate. At the same time, the GP-2 mRNA level was not modified by the hormonal treatment. These data demonstrate that glucocorticoids exert a positive control on the GGT expression in pancreatic cells at a post-transcriptional level. GGT, an enzyme of the glutathione metabolism, could play a significant role in protein packaging in secretory cells.

Animals↗
PubMed1996

Immunocytochemical and cytochemical demonstration of a novel selective lysosomal pathway (SLP) of secretion in the exocrine pancreas.

The intracellular distributions of lysosomal and zymogen granule (ZG) membrane proteins were analyzed in the pancreas exocrine acinar cell by cytochemical and immunocytochemical approaches. A strong signal was observed with acid phosphatase (AcPase) in the trans-Golgi network and condensing vacuoles, whereas mature ZG and acinar lumina were devoid of any detectable reaction. The enzyme appears to exit from the regulated pathway by a shedding process during conversion of condensing vacuoles to mature granules. Trimetaphosphatase (TMPase) shows no reaction in the Golgi apparatus and condensing vacuole but is present in immature granules. The exit from the regulated pathway appears to occur at a later stage of the ZG maturation process. A third lysosomal enzyme, nicotinamide adenine dinucleotide phosphohydrolase (NADPase), was found in the median cisterna of the Golgi stack, was undetectable in condensing vacuoles and ZG, but produced a strong signal in the acinar lumen. Our observations show that only one type of intermediate organelle can explain the transport of that enzyme from the Golgi apparatus to the acinar lumen, and it is represented by a subpopulation of lysosomal bodies (LBs) highly reactive for this enzyme. In parallel, immunocytochemical observations with specific antibodies to GP2, a major protein component of the ZG membrane, have confirmed that most of the GP2 molecules in the acinar lumen do not derive from the ZG compartment but rather are from a subpopulation of highly reactive lysosomal structures. Because both NADPase and GP2 co-localize in specific lysosomal structures, and because these LBs are extruded in the acinar lumen, we conclude that this subpopulation of LBs is involved in selective transport of some lysosomal enzymes from the Golgi apparatus to the acinar lumen. This selective lysosomal pathway of secretion can explain the kinetics of GP2 transport and release from the acinar cell that cannot be explained either by the constitutive or the regulated pathway of secretion.

Acid Anhydride Hydrolases↗
PubMed1996

Characterization of SNARE protein expression in beta cell lines and pancreatic islets.

Pancreatic beta cells and cell lines were used in the present study to test the hypothesis that the molecular mechanisms controlling exocytosis from neuronal cells may be used by the beta cell to regulate insulin secretion. Using specific antisera raised against an array of synaptic proteins (SNAREs) implicated in the control of synaptic vesicle fusion and exocytosis, we have identified the expression of several SNAREs in the islet beta cell lines, beta TC6-f7 and HIT-T15, as well as in pancreatic islets. The v-SNARE vesicle-associated membrane protein (VAMP)-2 but not VAMP-1 immunoreactive proteins were detected in beta TC6-f7 and HIT-T15 cells and pancreatic islets. In these islet-derived cell lines, this 18-kDa protein comigrated with rat brain synaptic vesicle VAMP-2, which was cleaved by Tetanus toxin (TeTx). Immunofluorescence confocal microscopy and electron microscopy localized the VAMP-2 to the cytoplasmic side of insulin containing secretory granule membrane. In streptolysin O permeabilized HIT-T15 cells, TeTx inhibited Ca2+-evoked insulin release by 83 +/- 4.3%, which correlated well to the cleavage of VAMP-2. The beta cell lines were also shown to express a second vesicle (v)-SNARE, cellubrevin. The proposed neuronal target (t)-membrane SNAREs, SNAP-25, and syntaxin isoforms 1-4 were also detected by Western blotting. The beta cell 25-kDa SNAP-25 protein and syntaxin isoforms 1-3 were specifically cleaved by botulinum A and C toxins, respectively, as observed with the brain isoforms. These potential t-SNARES were localized by immunofluorescence microscopy primarily to the plasma membrane in beta cell lines as well as in islet beta cells. To determine the specific identity of the immunoreactive syntaxin-2 and -3 isoforms and to explore the possibility that these beta cells express the putative Ca2+-sensing molecule synaptotagmin III, RT-PCR was performed on the beta cell lines. These studies confirmed that betaTC6-F7 cells express syntaxin-2 isoforms, 2 and 2', but not 2'' and express syntaxin-3. They further demonstrate the expression of synaptotagmin III. DNA sequence analysis revealed that rat and mouse beta cell syntaxins 2, 2' and synaptotagmin III are highly conserved at the nucleotide and predicted amino acid levels (95-98%). The presence of VAMP-2, nSec/Munc-18, SNAP-25 and syntaxin family of proteins, along with synaptotagmin III in the islet cells and in beta cell lines provide evidence that neurons and beta cells share similar molecular mechanisms for Ca2+-regulated exocytosis. The inhibition of Ca2+-evoked insulin secretion by the proteolytic cleavage of HIT-T15 cell VAMP-2 supports the hypothesis that these proteins play an integral role in the control of insulin exocytosis.

Animals↗
PubMed1995

Purification of pancreas type-I ATP diphosphohydrolase and identification by affinity labelling with the 5'-p-fluorosulphonylbenzoyladenosine ATP analogue.

The enzyme recently identified as type-I ATP diphosphohydrolase (ATPDase; EC 3.6.1.5) has been purified from the zymogen granule membrane of pig pancreas. After solubilization with Triton X-100 and chromatographies on ion-exchange and Affi-Gel Blue columns an approximate 3500-fold purification was obtained. The enzyme preparation with a specific activity of 45 units/mg of protein was much further purified by PAGE under non-denaturing conditions. The active band localized on the gel contained two proteins after SDS/PAGE and silver staining, corresponding to apparent molecular masses of 56 and 54 kDa. The identity of the ATPDase was confirmed by an affinity labelling technique with 5'-p-fluorosulphonylbenzoyladenosine (FSBA) as an ATP analogue. The latter was detected by a Western blot technique. A strong reaction was observed with the band corresponding to 54 kDa. N-terminal sequence analysis revealed that the 56 kDa protein has significant similarities (50-72%) with lipases, whereas the 54 kDa enzyme has no significant similarity with any known proteins. N-glycosidase F treatment confirmed the glycoprotein nature of the enzyme and suggested that the enzyme bears several N-glycosylation sites. Comparisons of molecular masses and biochemical properties show that this ATPDase is different from other reported mammalian ATPDases.

Adenosine↗
PubMed1994

Demonstration of an ectoATP-diphosphohydrolase (E.C.3.6.1.5.) in non-vascular smooth muscles of the bovine trachea.

An ectoATP-diphosphohydrolase (ATPDase) is put in evidence in non-vascular smooth muscles of the bovine trachea. The enzyme has an optimum pH of 7.0 and catalyzes the hydrolysis of the gamma- and beta-phosphate residues from extracellular triphospho- and diphosphonucleosides. It requires either Ca2+ or Mg2+ and is insensitive to ouabain, oligomycin and Ap5A. Sodium azide (20 mM), mercuric chloride (10 microM) and gossypol (35 microM) inhibit the enzyme activity by more than 45%. Polyacrylamide gel electrophoresis under non-denaturing conditions and kinetic properties, namely pH dependency profiles, heat inactivation and 60Co gamma-irradiation-inactivation curves, support the view that the same catalytic site is responsible for the hydrolysis of ATP and ADP to AMP. Accordingly, when both ATP and ADP were combined, reaction rates were not additive. With ATP, Km,app and Vmax,app were estimated at 15 +/- 2 microM and 1.9 +/- 0.1 mumol inorganic phosphate/min per mg of protein, respectively. From 60Co gamma-irradiation-inactivation curves, the molecular mass of the enzyme was estimated at 71 +/- 5 kDa. Enzyme markers indicate that the ATPDase is associated with the plasma membrane. Enzyme assays on trachea smooth muscle cells in suspension confirm that the catalytic site of this ATPDase is localized on the outer surface of the plasma membrane. Analysis of the biochemical properties shows many points of similarity between the tracheal ATPDase and the ATPDase recently described in the bovine lung.

Animals↗
PubMed1993

Glycoprotein 2 of zymogen granule membranes shares immunological cross-reactivity and sequence similarity with phospholipase A2.

Glycoprotein 2 (GP2), the major protein of rat pancreatic zymogen granule membranes (ZGMs), cross-reacted with an antiserum against porcine secretory phospholipase A2 (sPLA2). Amino acid sequence comparison showed 45% similarity and 23% identity between porcine PLA2 and the C-terminal portion of GP2. An antiserum to intestinal brush border Ca(2+)-independent PLA2 (bbPLA2) also recognized GP2. The antigenic and sequence similarities between GP2, sPLA2, and bbPLA2 imply that the role of GP2 in cellular function is associated with phospholipid binding and/or hydrolysis.

Amino Acid Sequence↗
PubMed1993

Demonstration of a novel type of ATP-diphosphohydrolase (EC 3.6.1.5) in the bovine lung.

A novel type of ATP-diphosphohydrolase (ATPDase) is demonstrated in bovine lung. The enzyme has an optimum pH of 7.5 and catalyzes the hydrolysis of the beta- and gamma-phosphate residues from diphospho- and triphosphonucleosides. It requires Ca2+ or Mg2+ and is insensitive to ouabain, an inhibitor of Na+/K(+)-ATPase, P1,P5-di(adenosine 5')-pentaphosphate, an inhibitor of adenylate kinase, and tetramisole, an inhibitor of alkaline phosphatase. In contrast, sodium azide (10 mM), a known inhibitor of ATPDases and mitochondrial ATPases, as well as mercuric chloride (10 microM) and gossypol (2,2'-bis[8-formyl-1,6,7-trihydroxy-5-isopropyl-3-methylnaphthalene]) (35 microM) are powerful inhibitors of this enzyme. The same inhibition profile is obtained with ATP or ADP as substrate, thereby supporting the concept of a common catalytic site for these substrates. This is further confirmed by enzyme localization after polyacrylamide gel electrophoresis under nondenaturing conditions and by kinetic properties, namely pH dependence profiles, heat inactivation, and 60Co irradiation-inactivation curves. The native molecular mass of the enzyme calculated from 60Co gamma-irradiation-inactivation curves is estimated at 70 +/- 3 kDa, whereas Km,app and Vmax,app of the ATPDase are evaluated at 7 +/- 2 microM and 1.1 +/- 0.3 mumol of Pi/min/mg protein, respectively. A comparison of the kinetic properties of this ATPDase with those of pig pancreas (Type I) and bovine aorta (Type II) lead us to believe that this enzyme is an hitherto undescribed type of ATPDase. By reference to the previously described ATPDase, we propose to identify this enzyme as ATPDase Type III (EC 3.6.1.5).

Animals↗
PubMed1993

Immunocytochemical localization of gamma-glutamyltranspeptidase, GP-2 and amylase in the rat exocrine pancreas: the concept of zymogen granule membrane recycling after exocytosis.

We localized gamma-glutamyltranspeptidase (GGT) in the rat pancreas by immunocytochemistry using the protein A-gold technique. The enzyme was found in the apical and zymogen granule (ZG) membranes of the pancreatic acinar cell. With ZG at the onset of exocytosis, labeling was seen over membrane, whereas content was unreactive. In the acinar lumen, the enzyme was generally associated with small vesicles previously described as "pancreasomes." This observation corroborates a recent proposal that a membrane-shedding process is associated with exocytosis in the exocrine pancreas. It also implies that some elements of the ZG membrane are not recycled after exocytosis. The cellular distribution of GGT was compared with GP2, another glycoprotein component of the ZG membrane, and differences in localization indicate different fates for these two proteins. Indeed, GP2 shows a strong signal with the basolateral membrane, whereas in the case of GGT the signal is barely detectable. The reverse situation is observed on the apical plasma membrane, GGT producing a much stronger signal than GP2. The failure to detect GGT in lysosomal structures, combined with the fact that some endocytic-like vacuoles in the vicinity of the apical plasma membrane give a positive reaction, supports the view that some GGT molecules are recycled in the ZG membrane after exocytosis. Our observations clearly demonstrate that a fraction of the protein components of the ZG membrane are not recycled after exocytosis, raising new questions regarding the concept of membrane recycling associated with regulated secretion.

Amylases↗
PubMed1992

Kinetic properties of type-II ATP diphosphohydrolase from the tunica media of the bovine aorta.

The kinetic properties of type-II ATP diphosphohydrolase are described in this work. The enzyme preparation from the inner layer of the bovine aorta, mostly composed of smooth muscle cells, shows an optimum at pH 7.5. It catalyzes the hydrolysis of tri- and diphosphonucleosides and it requires either Ca2+ or Mg2+ for activity. It is insensitive to ouabain (3 mM), an inhibitor of Na+/K(+)-ATPase, to tetramisole (5 mM), an inhibitor of alkaline phosphatase, and to Ap5A (100 microM), an inhibitor of adenylate kinase. In contrast, sodium azide (10 mM), a known inhibitor for ATPDases and mitochondrial ATPase, is an effective inhibitor. Mercuric chloride (10 microM) and 5'-p-fluorosulfonylbenzoyl adenosine are also powerful inhibitors, both with ATP and ADP as substrates. The inhibition patterns are similar for ATP and DP, thereby, supporting the concept of a common catalytic site for these substrates. Apparent Km and Vmax, obtained with ATP as the substrate, were evaluated at 23 +/- 3 microM and 1.09 mumol Pi/min per mg protein, respectively. The kinetic properties of this enzyme and its localization as an ectoenzyme on bovine aorta smooth muscle cells suggest that it may play a major role in regulating the relative concentrations of extracellular nucleotides in blood vessels.

Animals↗
PubMed1992

Characterization of ATP-diphosphohydrolase activities in the intima and media of the bovine aorta: evidence for a regulatory role in platelet activation in vitro.

The inner layer of the aorta contains the enzyme ATP diphosphohydrolase (ATPDase: EC 3.6.1.5) which catalyzes the sequential phosphorolysis of ATP----ADP----AMP. Two zones of the inner layer, the intima and media, were separated and both were shown to contain ATPDase activity of similar specific activity (0.08 and 0.10 U/mg protein, respectively). However, the media exhibited about 100-times more enzyme activity than the intima. Both preparations were virtually identical with respect to pH optima (7.5), migration patterns after electrophoresis under non-denaturing conditions, relative rates of ATP and ADP hydrolysis and potency to inhibit ADP-induced platelet aggregation in both human platelet-rich plasma and whole blood. The IC50 values for ADP (2 microM)-induced aggregation were 6.8 and 12.9 mU/ml in platelet-rich plasma and whole blood, respectively. Addition of ATPDase to platelets pre-aggregated with ADP resulted in a dose-dependent disaggregation in platelet-rich plasma (IC50 4.9 mU/ml), but not in whole blood. When both ATPDase (5.6-58.7 mU/ml) and ATP (0.5-10 microM) were added to platelet-rich plasma, there was an immediate dose-dependent aggregation of platelets followed by a slowly developing disaggregation. These data show that ATPDase is present in both the intima and media layers of bovine aorta and suggest a dual role for this enzyme in platelet activation. By converting ATP released from damaged cells into ADP, the enzyme could facilitate platelet aggregation at the site of vascular injury, whereas the subsequent conversion of ADP to AMP could inhibit or reverse platelet aggregation. The consequence of these activities would be to control the growth of a platelet thrombus.

Adenosine Triphosphate↗
PubMed1992

A unique secretory behavior for GP2 in the exocrine pancreas.

GP2 is the major glycoprotein component of the zymogen granule membrane of pancreas acinar cell. It was recently found that this protein is secreted and forms a network of fibrils in pancreatic juice. In the present work, with an ELISA, we have examined the fluctuations of GP2 levels in the juice collected in resting and stimulated conditions. In anaesthetized fasting rats, GP2 represented about 6-8% of total protein output. Stimulation by caerulein, carbachol, or their combination caused an immediate and significant burst in both protein and GP2 outputs. However, the GP2 increase did not parallel protein release. Its relative proportions decreased with the intensity of the stimulus. The secretory behavior of GP2 cannot be explained with the current concepts of constitutive and regulated pathways of secretion and suggests the existence of a yet undefined mode of secretion for this protein.

Animals↗
PubMed1992

Histochemical and immunocytochemical characterizations of laminated bodies in the pancreas acinar lumen.

Combined adrenalectomy and castration cause numerous morphological alterations in the exocrine pancreas of the rat. Accumulation of laminated bodies (LB) in the acinar lumen is one of these alterations. A series of classical histological stains was applied to identify the components of these structures. A positive reaction was observed with periodic acid-Schiff, Congo red, and Alcian blue (pH 2.5). The first stain reacts with neutral and some acid mucosubstances and the second with amyloid, whereas the last one reacts with sulfated and nonsulfated acid mucosubstances. The LB also responded to Luxol fast blue, indicating the presence of lipids, an observation that is in agreement with the osmiophilic properties of these structures. A more specific identification of LB components was carried out with the immunocytochemical protein A-gold technique. Presence of gamma-glutamyltranspeptidase (gamma-GT) and GP2, two glycoproteins known to be secreted by the pancreas, was tested. The gamma-GT was associated with LB whereas GP2 was found in the lumen but not associated with these structures. Amylase was undetectable when LB occupied the lumen, suggesting that the process leading to production of LB also blocks secretory activity. To determine if diet influences LB accumulation in the pancreas acinar lumen, their frequency was compared in rats fed Purina Lab Chow or a lipid-free synthetic diet. A significant increase was observed in castrated-adrenalectomized rats fed the latter diet. This increase corresponded to a pronounced reduction in the number of zymogen granules (ZG) in the acinar cell. Our results show that LB are made of lipids, neutral mucosubstances, and nonsulfated acid mucosubstances, and that hormonal (steroids) and dietary factors (lipids) influence their accumulation.

Adrenalectomy↗
PubMed1992

ATLAS-plus: multimedia instruction in embryology, gross anatomy, and histology.

ATLAS-plus [Advanced Tools for Learning Anatomical Structure] is a multimedia program used to assist in the teaching of anatomy at the University of Michigan Medical School. ATLAS-plus contains three courses: Histology, Embryology, and Gross Anatomy. In addition to the three courses, a glossary containing terms from the three courses is available. All three courses and the glossary are accessible in the ATLAS-plus environment. The ATLAS-plus environment provides a consistent set of tools and options so that the user can navigate easily and intelligently in and between the various courses and modules in the ATLAS-plus world. The program is a collaboration between anatomy and cell biology faculty, medical students, graphic artists, systems analysts, and instructional designers.

Anatomy↗