Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.24.3 (collagenase)
18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Forskolin synergistically potentiated adenosine 3',5'-cyclic monophosphate formation by prostaglandin E1 (PGE1) in rat normal hepatocytes freshly prepared by collagenase digestion and rat ascites hepatoma AH66 cells, but dose-dependently inhibited the accumulation by PGE1 in AH66F cells. Forskolin activated adenylate cyclase in a dose-dependent manner in homogenates of all cell lines. In normal hepatocytes and AH66 cells, simultaneous addition of forskolin and other adenylate cyclase activators [isoproterenol (IPN), PGE1, guanosine 5'-triphosphate sodium salt (GTP), 5'-guanylylimidodiphosphate sodium salt (Gpp (NH)p), NaF, cholera toxin, islet activating protein and MnCl2] gave greater than additive responses. On the other hand, in AH66F cells, the effect of forskolin on adenylate cyclase was hardly influenced by GTP, but forskolin diminished the activities induced by high concentrations of GTP to that by the diterpene alone. Forskolin also significantly inhibited the PGE1-stimulated and the guanine nucleotide binding regulatory protein-stimulated activities. Because AH66F cells were insensitive to IPN, the combination with forskolin and IPN gave similar activity to that obtained with the diterpene alone. The effect of forskolin on the activation by manganese ion was neither synergistic nor inhibitory but was additive in AH66F cells. These results suggest that forskolin promotes the interaction between the stimulatory guanine nucleotide binding regulatory protein and the catalytic unit in normal hepatocytes and AH66 cells, but in AH66F cells forskolin interferes with the coupling of the two components of adenylate cyclase.
...
PMID:Stimulatory and inhibitory effects of forskolin on adenylate cyclase in rat normal hepatocytes and hepatoma cells. 254 54

Previous work has demonstrated that adult newt cardiac myocytes possess a proliferative ability in response to an experimentally induced injury, in vivo. This study describes an in vitro model in which the proliferative events of the adult cardiac myocyte may be studied. Ventricles were minced and then enzymatically dissociated in a Ca++- and MG++-free salt solution containing 0.5% trypsin and 625 U/ml of CLS II collagenase for 8 to 10 hours at 25 degrees C. Enzyme digests were preplated and then cultured on bovine corneal endothelial-derived basement membrane "carpets" in either serum-free or serum-supplemented modified Leibovitz's medium for up to 30 days. Light and transmission electron microscopic characterization demonstrated that a majority of the myocytes underwent an initial period of disorganization characterized by a "rounding up" of the cell and a loss of myofibrillar organization. Once the myocytes had attached to the culture substratum they began to spread out, underwent a reassembly of their contractile elements, resumed spontaneous contractions, and demonstrated ultrastructural evidence of protein synthesis. Mitosis was observed in several myocytes 8 to 15 days following isolation. In 15-day serum-supplemented and serum-free cultures, 6.5% +/- 0.9% and 8.1% +/- 1.4% of the myocytes were binucleated, respectively. These results demonstrate that adult newt ventricular myocytes can be successfully placed into primary culture and are capable of undergoing mitosis. This work may be considered as a foundation for future investigations which will focus on the mechanisms which control cardiac myocyte proliferation.
...
PMID:Primary cell culture and morphological characterization of ventricular myocytes from the adult newt, Notophthalmus viridescens. 265 85

Interlobular duct fragments from the pancreas of the rat were isolated by collagenase digestion and filtration, embedded in a matrix of rat-tail collagen, and cultured in a 1:1 mixture of Dulbecco's minimal essential and Ham's F12 media supplemented with cholera toxin (CT, 100 ng/ml) and epidermal growth factor (EGF, 10 ng/ml) in addition to supplements used previously, thereby improving the yield of ducts by a factor of two compared with previous results. The ducts were harvested by digestion of the collagen matrix with collagenase and were then dissociated by treatment with EDTA in divalent cation-free salt suspended in collagen and cultured as were the ducts. Numerous cysts appeared as a function of time and some of these enlarged dramatically. Some of the larger cysts exhibited secondary tubular processes extending into the surrounding collagen. The addition of bovine pituitary extract (BPE, 50 micrograms/ml) doubled the number of cysts, whereas omission of serum or CT + EGF reduced the number. BPE or forskolin could substitute effectively for CT. Agents that stimulate (secretin) or inhibit (e.g., ouabain or acetazolamide) fluid-electrolyte secretion in vivo had no effect on the number or average diameter of the cysts. The cysts were 83 to 88% epithelial with the balance of the cells being fibroblastic in appearance. Some cysts consisted only of epithelium. The proliferative capacity of the cystic epithelium was shown by the presence of mitotic figures and by an autoradiographic labeling index of 22 to 30% after a 24-h exposure to [3H]thymidine. The labeling index was reduced by the omission of CT + EGF. Transmission electron microscopy showed that the cysts exhibited morphologic features of duct epithelium in vivo, including apical microvilli, lateral interdigitations of the plasma membrane, and typical cytoplasmic organelles.
...
PMID:Rat pancreatic interlobular duct epithelium: isolation and culture in collagen gel. 276 30

To obtain information about the evolution of acetylcholinesterase (AChE), we undertook a study of the enzyme from the skeletal muscle of the lamprey Petromyzon marinus, a primitive vertebrate. We found that the cholinesterase activity of lamprey muscle is due to AChE, not pseudocholinesterase; the enzyme was inhibited by 1,5-bis(4-allyldimethylammonium phenyl) pentane-3-one (BW284C51), but not by tetramonoisopropyl pyrophosphortetramide (iso-OMPA) or ethopropazine. Also, the enzyme had a high affinity for acetylthiocholine and was inhibited by high concentrations of substrate. A large fraction of the AChE was found to be glycoprotein, since it was precipitated by concanavalin A-agarose. Optimal extraction of AChE was obtained in a high-salt detergent-containing buffer; fractional amounts of enzyme were extracted in buffers lacking salt and/or detergent. These data suggest that globular and asymmetric forms of AChE are present. On sucrose gradients, enzyme that was extracted in high-salt detergent-containing buffer sedimented as a broad peak of activity corresponding to G4; additionally, there was usually a peak corresponding to A12. Sequential extraction of AChE in conjunction with velocity sedimentation resolved minor forms of AChE and revealed that the G1, G2, G4, A4, A8, and A12 forms of AChE could be obtained from the muscle. The identity of the forms was confirmed through high-salt precipitation and collagenase digestion. The asymmetric forms of AChE were precipitated in low ionic strength buffer, and their sedimentation coefficients were shifted to higher values by collagenase digestion.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Acetylcholinesterase from the skeletal muscle of the lamprey Petromyzon marinus exists in globular and asymmetric forms. 288 57

The nephritogenic antigen of Heymann's nephritis (HN), gp330, was previously demonstrated (4-9) to be a resident glycoprotein of coated pits in the glomerular and proximal tubule epithelium of rats, and anti-gp330 IgG given intravenously was found to form IDs in glomeruli (passive HN). The purpose of this study was to investigate the detailed events that occur in the formation of IDs in passive HN. HN was induced by the injection of either 125I-labeled or unlabeled anti-gp330 IgG. At various times after injection (15 min to 8 d) the kidneys of some of the injected rats were fixed by perfusion, and the distribution of the rabbit IgG was determined by immunofluorescence and by immunoelectron microscopy. Glomeruli were isolated from the kidneys of injected rats and used for isolation of GBM fractions or for elution of the bound IgG. At 15 min to 1 h after injection, the rabbit IgG was localized by immunocytochemistry exclusively in coated pits along the podocyte plasmalemma facing the GBM. By 1-8 d, anti-gp330 IgG was detected in larger electron-dense IDs often located under the slit diaphragms. Serial sectioning revealed that each of the IDs maintained contact with a coated pit at some level. When GBMs isolated from rats given radiolabeled anti-gp330 IgG were examined by electron microscopy, the IDs were found to remain attached to the GBMs as early as 15 min after injection and coisolated with them at all time points. By double-immunolabeling of the isolated GBMs with two sizes of gold particles, both the antigen (gp330) and the anti-gp330 IgG could be demonstrated in IDs at all time points. When the amount of radiolabeled anti-gp330 bound to GBM fractions was compared with that of isolated glomeruli, it was found that 20% of the radiolabel remained bound to the purified GBMs at 15 min after injection, and 90% at 3 d. The bound IgG was released only by treatments that disrupt antibody-antigen complexes (high and low pH), but not by the other treatments we tried (detergent, high salt, heparinase, or collagenase digestion). When the IgG bound to glomeruli was eluted with acid citrate buffer 3 d after injection, it was found to specifically immunoprecipitate only gp330 from detergent-solubilized 125I-labeled kidney microvillar vesicles. By isoelectric focusing the eluate was found to be enriched in IgGs with acidic isoelectric points.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Initial events in the formation of immune deposits in passive Heymann nephritis. gp330-anti-gp330 immune complexes form in epithelial coated pits and rapidly become attached to the glomerular basement membrane. 288 90

Cytosols from cultured myoblast cells (G-8 and H9c2) prepared in high salt (0.3 M KCl) possesses receptor like proteins for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) that sediment in the 3.2 S region of sucrose gradients. These receptors were characterized as having high affinity (Kd less than 0.1 nM) for 1,25-(OH)2D3 and are in low capacity (less than 80 fmol/mg of cytosol protein). Analog competition for receptor binding revealed that 1,25-(OH)2D3 was more potent than 24,25-(OH)2D3, or 25-(OH)2D3 for displacement of 1,25-(OH)2[3H]D3 from these 3.2 S region sedimenting receptors. Furthermore, the receptor proteins had affinity for DNA and eluted from Sephacryl S-200 as a macromolecule with Stokes radius (Rs) of 32 A. High salt cytosol from collagenase-dispersed skeletal muscle cells was also found to possess a 3.2 S 1,25-(OH)2D3 receptor-like protein. The 1,25-(OH)2D3 receptor concentration in both G-8 and H9c2 myoblast lines was found to down-regulate by 50-70% when cells were stimulated to differentiate to myotubes by lowering fetal calf serum to 5% of the medium. Moreover, we demonstrated that 1,25-(OH)2D3 can inhibit DNA synthesis and cell proliferation of the G-8 myoblast cells in a dose-dependent manner. 1,25-(OH)2D3 was more potent at inhibiting cell proliferation in cells grown in 5% serum than in 20% serum. The data suggest that 1,25-(OH)2D3 can act directly on muscle myoblast via a 1,25-(OH)2D3 receptor that is similar to those found in intestine and bone. The data support the possibility that muscle is a target tissue for 1,25-(OH)2D3 and the hormone may act to initiate terminal differentiation of myoblast cells.
...
PMID:Identification of 1,25-dihydroxyvitamin D3 receptors and activities in muscle. 299 Dec 24

The phenomenon of electric taste was investigated by recording from the chorda tympani nerve of the rat in response to both electrical and chemical stimulations of the tongue with electrolytes in order to gain some insight into its mechanism on both a neurophysiological and biophysical basis. The maximum neural response levels were identical for an individual salt (LiCl, NaCl, KCl, or CaCl2), whether it was presented as a chemical solution or as an anodal stimulus through a subthreshold solution. These observations support the idea that stimulation occurs by iontophoresis of ions to the receptors at these current densities (less than 100 microA/cm2). Electric responses through dilute HCl were smaller than the chemically applied stimulations, but the integrated anodal responses appeared similar to chemical acid responses, as evidenced by an OFF response to both forms of stimuli. Hydrogen may be more permeant to the lingual epithelium and would thus be shunted away from the taste receptors during anodal stimulation. When the anion of electric taste was varied via subthreshold salt solutions, the response magnitude increased as the mobility of the anion decreased. The transport numbers of the salts involved adequately explains these differences. The physical aspects of ion migration occurring within the adapting fluid on the tongue are also discussed. Direct neural stimulation by the current appears to occur only at higher current densities (greater than 300 microA/cm2). If the taste cells of the tongue were inactivated with either iodoacetic acid (IAA) or N-ethyl maleimide (NEM), or removed with collagenase, then responses from the chorda tympani could be obtained only at these higher current densities. Latency measurements before and after IAA or NEM treatment corroborated these findings. The results are discussed in terms of several proposed mechanisms of electric taste and it is concluded that an ion accumulation mechanism can adequately explain the data.
...
PMID:Neurophysiological and biophysical evidence on the mechanism of electric taste. 299 76

Prepuberal (P) gilts were induced to ovulate with pregnant mare serum gonadotropin followed 72 h later by human chorionic gonadotropin (hCG). Three P gilts and three mature (M) gilts each were ovariectomized on d 10, 14, 18, 22 and 26 (d 0 = day of hCG for P gilts and onset of estrus for M gilts). Gilts ovariectomized on d 14, 18, 22 and 26 were hysterectomized on d 6 to ensure maintenance of the corpora lutea (CL). Two to five grams of minced luteal tissue were dispersed using collagenase and hyaluronidase in HEPES buffered salt solution supplemented with glucose and bovine serum albumin. Dispersed cells were rinsed in Dulbecco's Modified Eagle Medium (DMEM), counted (ratio of large to total number of luteal cells determined) and then incubated for 1 h in DMEM. With aliquots standardized to 2.5 X 10(4) viable, large cells (greater than 25 micron diameter) were incubated in 1 ml DMEM for 2 h in the presence of either 10, 50, 100 or 1,000 ng luteinizing hormone (LH); .1, 1, 10 or 100 ng hCG; 10, 100 or 1,000 ng norepinephrine (NE) or either .75, or 1.5 mM dibutyrl cyclic adenosine monophosphate (dbcAMP). Progesterone (P4) in the medium was quantified by radioimmunoassay. Basal P4 production (no P4 stimulator added to the medium) on d 10, 14, 18, 22 and 26 for P gilts was 246 +/- 9, 66 +/- 4, 64 +/- 6, 41 +/- 3 and 69 +/- 6 ng/ml medium, respectively, and for M gilts was 281 +/- 12, 128 +/- 8, 53 +/- 4, 82 +/- 6, 101 +/- 5 ng/ml medium, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Comparison of induced corpora lutea from prepuberal gilts and spontaneous corpora lutea from mature gilts: in vitro progesterone production. 303 Sep 95

The glycosaminoglycans (GAG), glycoproteins and collagen in bovine aorta and venous tissue have been studied. The concentration of hyaluronic acid and dermatan sulphate was significantly more in the venous tissue while chondroitin sulphates were higher in the aorta. Sequential extraction with phosphate buffered saline (PBS) collagenase, hyaluronidase and urea was also carried out with the two tissues. The GAG extractable by PBS and collagenase digestion were more in the aorta. The total aortic glycoproteins had significantly lower hexose and higher sialic acid. The PBS extractable glycoproteins of the venous tissue had more hexose and fucose. The glycoproteins released by collagenase digestion of the venous tissue had lower sialic acid and higher fucose, while glycoprotein released by hyaluronidase digestion had lower sialic acid and higher hexose and fucose. Urea extractable glycoproteins had lower fucose and sialic acid in the venous tissue. Venous tissue had higher total collagen and acid and salt soluble collagen while insoluble collagen was more in the aorta. The total GAG in the venous tissue had greater anticoagulant activity while the aortic GAG bound significantly more serum lipoproteins.
...
PMID:Studies on the macromolecular components of the bovine aortic and venous tissue. 309 9

Normal adult rabbit corneas were digested with 5% pepsin and their collagens extracted with acetic acid. Collagen extracts were fractionated by differential salt precipitation. The 2.5 M NaCl fraction was then redissolved with tris buffer and precipitated with sodium acetate. The precipitate contained a high-molecular-weight disulfide-bonded aggregate which, upon reduction with mercaptoethanol, was converted into three distinct polypeptides having molecular weights between 45 and 66 Kd. These physical characteristics, together with the susceptibility of these polypeptides to collagenase and their amino acid composition, identified the high molecular weight aggregate as type VI collagen. Corneas from neonate rabbits and adult corneas containing 2-week-old scars were organ cultured in the presence of [14C] glycine to incorporate radiolabel into collagen. Tissues were digested with 0.02% pepsin and their collagens extracted with formic acid. The total radioactivity of the extracts and tissue residues was determined before the collagens were separated by SDS-polyacrylamide slab gel electrophoresis. Radioactive collagen polypeptides bands were then stained with Coomassie blue, processed for fluorography, and analyzed by densitometry. The results show that: (1) type VI collagen is synthesized by neonate corneas and healing adult corneas; (2) it is not readily solubilized from either corneal tissue by 0.02% pepsin digestion and formic acid extraction; and (3) the proportion of type VI collagen deposited in scar tissue is markedly lower than that found in neonate corneas.
...
PMID:Heterogeneity of collagens in rabbit cornea: type VI collagen. 313 Mar 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---