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)

The pathophysiological biology of human hypertrophic scar was examined in a long-term organ culture system. Fresh full-thickness, thin slices of scar were placed in petri dishes. Tissue was successfully maintained for 2 weeks in an environment made up of CMRL-1066 medium, fetal bovine serum, insulin, and hydrocortisone under an environment of 40% O2, 5% CO2, and 55% N2 at 37 degrees C on a rocking platform. Histologically the explants were viable and remained differentiated. The omission of hydrocortisone caused localized destruction of the connective tissue matrix under the epidermal layer. Transplanting the epidermis to the adipose surface of an explant before culturing in hydrocortisone-free medium, produced localized connective tissue matrix destruction only within the deep dermal layer. Removal of the epidermis before culturing in hydrocortisone-free medium produced no localized connective tissue matrix destruction. Culture medium from intact explants maintained in hydrocortisone-free media had higher levels of latent collagenase activity compared to epidermal free explants and intact explants in hydrocortisone-containing medium. This hypertrophic scar latent collagenase had a molecular weight estimated to be 33,000 by molecular-sieve chromatography. The active form of the enzyme had a molecular weight estimated to be 26,000. When examined by gel electrophoresis, activated collagenase cleaved types I and III native collagens, producing TC-A peptide fragments of alpha chains. Type V collagen was not cleaved by this enzyme. Metal chelators such as 1,10-phenanthroline blocked enzymatic activity. Serine and sulfhydryl proteolytic inhibitors showed no effects. Intact hypertrophic scar has the capacity to produce collagenase which appears responsible for the destruction of the connective tissue matrix of the scar. The production of hypertrophic scar collagenase is somehow controlled by the epidermis.
...
PMID:Epidermis promotion of collagenase in hypertrophic scar organ culture. 632 10

The characteristics of alpha-adrenoceptors in rat myocardium were investigated by specific binding of [3H]prazosin to cells isolated from adult rat heart by perfusion with collagenase and hyaluronidase. The cells were incubated in Krebs-Ringer bicarbonate buffer gassed with 95% O2 and 5% CO2 at 31 degrees with the appropriate concentrations of the different ligands. Non-specific binding was defined by the addition of 10(-5) mole/l. phentolamine. The binding of [3H]prazosin was saturable and reached equilibrium within 15 min. Scatchard analysis showed a straight line giving an apparent dissociation constant, Kd, equal to 155.9 +/- 8.0 pmole/l. and a maximal number of binding sites equal to 76.7 +/- 11.1 fmole/mg protein. Inhibition of specific [3H]prazosin binding by different adrenergic blockers showed the order of potency characteristic of alpha 1-adrenoceptors: prazosin much greater than phentolamine greater than yohimbine much greater than propranolol. Inhibition by adrenergic agonists showed the order of potency: adrenaline greater than noradrenaline = phenylephrine greater than isoprenaline. The same orders of potency were observed in the presence of propranolol. However, propranolol slightly decreased the affinity for noradrenaline and phenylephrine. Hofstee analyses of the inhibition curves showed two binding components for all ordinary alpha-adrenoceptor blockers and agonists including unlabelled prazosin. In contrast, [3H]prazosin showed only one binding component. Both binding components were of the alpha 1-adrenoceptor subtype according to the order of potency of blockers. The different ligands had different affinity ratios for the two binding components giving them different profiles. Trifluoperazine, a phenothiazine compound, also had high affinity for the [3H]prazosin binding sites. This drug, however, apparently detected one class of binding sites only, as interpreted from the Hofstee analysis. Hill analyses of the inhibition data consistently yielded Hill constants, nH, in the range 0.75-0.85 except for [3H]prazosin, where nH = 1.02 and for trifluoperazine, where nH = 1.07. Although the two binding components may serve different functions, it seems impossible at present to relate the negative and the positive inotropic components, respectively, of the alpha-adrenergic inotropic response observed in functional studies only to one or the other binding component.
...
PMID:Specific binding of [3H]prazosin to myocardial cells isolated from adult rats. 632 25

Perinatal rat islets of Langerhans, isolated and cultured in vitro, were examined following long-term allotransplantation across a major histocompatibility barrier in nonimmunosuppressed recipients. Islets were isolated to varying degrees of purity without the use of collagenase digestion. Newborn bovine serum was a component of the incubation medium and the atmosphere during culture was air: 5% CO2. Islets transplanted without rigorous purification were fully rejected by 14 days posttransplantation. However, if islets were maintained in subculture, permitting their subsequent meticulous purification, no evidence of rejection was observed after 45 days at the kidney subcapsular site. Grafts consisted of morphologically intact islets. The three major endocrine cell types of the islet were identified by immunocytochemical localization of insulin, glucagon, and somatostatin. These results demonstrate that perinatal islets can exhibit altered immunogenicity, as evidenced by prolonged allograft survival, when isolated and purified by the nonenzymic in vitro method.
...
PMID:Modification of allograft immunogenicity in perinatal islets isolated and purified in vitro. 642 93

A method is described which allowed in-vitro measurements of metabolic CO2 production from [U-14C]-substrates by single pieces of kidney tubules. The tubules were isolated by microdissection from collagenase treated rat kidneys. Single pieces of various distal nephrons portions were incubated in 1 microliter of bicarbonate free minimum essential medium containing the required [U-14C]-substrate (about 0.2 mu Ci per sample), and the 14CO2 produced was continuously trapped into a 2-microliter KOH droplet. The KOH droplets were replaced every 30 min. Metabolic CO2 production from the labelled substrate used was calculated as picomoles CO2 per mm of tubular length per minute, by dividing the KOH radioactivity by the specific radioactivity per carbon of the substrate present in the incubate [( U-14C] plus cold substrate concentrations). Under these conditions, it was established that single pieces of tubule could sustain almost constant CO2 production for at least 2 h at 31 degrees C. Experiments testing four different conditions with five to six replicate samples per condition were performed in order to compare oxidative metabolism in medullary (MAL) and cortical (CAL) thick ascending limbs, medullary (MCT) and cortical (CCT) collecting tubules and, in a few instances, proximal convoluted tubules (PCT) and early distal convoluted tubules (DCT).(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Metabolic CO2 production by isolated single pieces of rat distal nephron segments. 643 91

It is well-known that the hypothalamus predominantly exerts an inhibitory control on prolactin secretion and that dopamine (DA) is the main prolactin inhibiting factor (PIF). In addition, the hypothalamus contains prolactin-releasing factors (PRF). Thyrotropin-releasing hormone (TRH), vasoactive intestinal polypeptide (VIP) and peptide-histidine-isoleucine (PHI) are the components of PRF. However, the detailed mechanism by which the peptides release prolactin (PRL) at the pituitary level is still unknown. Therefore, in this paper, an in vitro perifusion system using the cell column of cultured rat pituitary cells attached on Cytodex beads was employed to investigate the mechanism of PRL release. The rat anterior pituitary cells were isolated using collagenase, and the dispersed pituitary cells were cultured with swollen Cytodex beads in Dulbecco's modified Eagle medium (DMEM) containing fetal calf serum at 37 degrees C in 5% CO2 and 95% air for 2--3 days. The cultured anterior pituitary cells attached on Cytodex beads were packed in a column and perifused with DMEM at a constant flow rate of 0.4 ml/min using a peristaltic pump. The following results were obtained. A five minute perifusion with 100 pg/ml to 100 ng/ml TRH caused a significant increase of PRL in a dose-related manner. A continuous perifusion with 2 ng/ml or 10 ng/ml DA inhibited PRL release in a dose-related manner. When TRH at a dose of 1 ng/ml, 10 ng/ml or 100 ng/ml was perifused for 120 min at a rate of 0.4 ml/min, a large amount of PRL was released during the early period of the TRH infusion, and then the PRL release gradually decreased to the basal levels in spite of the continuous TRH infusion. An additional TRH, of which the concentration was ten-fold higher than the TRH level in the continuous infusion, when added at the end of the continuous TRH infusion, had no effect on PRL release. On the other hand, a 5 minute TRH infusion given at 30 min after the end of the continuous TRH infusion caused a significant increase in PRL release. A continuous perifusion with 1 mM 8-bromo-cyclic AMP caused a small but continuous PRL release. An additional continuous 8-bromo-cyclic AMP infusion during the late period of a continuous TRH infusion caused a continuous PRL release similar to that induced by the continuous infusion of cyclic AMP only. A short period perifusion with 1 X 10(-9)M to 1 X 10(-7)M of vasoactive intestinal polypeptide (VIP) enhanced a significant increase of PRL release in a dose-related manner, but the amounts of PRL release induced by VIP were smaller than those induced by TRH.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:[A study on the prolactin releasing mechanism using an in vitro perfusion system with a cell column of cultured rat anterior pituitary cells]. 644 Aug 13

To determine intracellular pH gradients rabbit renal cortical tubular cells were prepared by collagenase separation, suspended in a Krebs-Ringer buffer solution, and gassed with 95% O2-5% CO2 in a special nuclear magnetic resonance (NMR) probe. Renal tubular cellular pH was determined simultaneously from the distribution of 14C-dimethadione (DMO) (pHDMO) or the chemical shift of inorganic phosphate (pHNMR). Experiments were performed at different external pH values (pHe) ranging between 6.52 and 7.20. pHNMR, a measure of cytoplasmic pH, changed by an amount equal to the change in pHe. pHDMO, however, a measure of cytoplasmic plus mitochondrial pH, changed less than pHe as the latter increased. pHDMO, higher than pHNMR at low pHe, became equal to pHNMR at higher pHe values. By use of assumed mitochondrial volumes of 30-40% mitochondrial pH was calculated from pHDMO and pHNMR. Mitochondrial pH remained relatively constant over the entire pHe range studied. Since cytoplasmic pH fell as pHe was lowered, the transmitochondrial pH gradient increased at low pHE values. These findings suggest that the transmitochondrial pH gradient may be important in regulating metabolism.
...
PMID:Estimation of cellular pH gradients with 31P-NMR in intact rabbit renal tubular cells. 647 6

The isolated islets of Langerhans are the most available donors for transplantation. As the preservation of the isolated islets is difficult, we attempted to keep these tissues viable by use of an organ culture. Islets of Langerhans from adult Wistar rats were isolated by a collagenase technique and cultured in air-CO2 (95-5%) incubator at 37 degrees C. Insulin contents of the culture media which was changed every 3 days ranged from 1097 to 1434 microunits/ml during the 80 days' culture period. Transplantation of these islets into the portal vein of streptozotocin-induced diabetic rats resulted in a good recovery from the diabetic state. These studies indicate that cultured islets do preserve their original biological abilities.
...
PMID:Culture of the islets of Langerhans for transplantation. 680 49

In this paper the theoretical basis of alloreactivity and its relevance to transplantation biology is discussed prior to a review of work showing that culture of adult mouse pancreatic islets for 7 days in 95% O2 and 5% CO2 facilitates successful grafting to nonimmunosuppressed allogeneic recipients. These allografts function by reversing both chemically induced and spontaneous diabetes. The fetal mouse pancreas is more immunogenic than adult islets, and even after a culture period of 10 days in 95% O2 and 5% CO2, BALB/c allografts are consistently rejected by nonimmunosuppressed recipient mice. The immunogenicity of fetal pancreas is thought to be due to the presence of contaminating lymphoreticular cells in the mesentery surrounding the fetal pancreas. Digestion of the fetal pancreas with collagenase allows the isolation of proislets that develop into functional islet tissue on transplantation. Fetal proislets are less immunogeneic than the whole fetal pancreas and may provide a source of tissue for clinical transplantation. Established islet allografts are relatively stable and are not rejected following nonspecific stimulation of the recipient's immune system or following passive transfer of either antibody or antibody and complement. After prolonged residence in the recipient a state of allograft tolerance develops and such grafts resist rejection by specific stimulation of the recipient. The administration of donor antigen in the form of uv-irradiated cells enforces this state of allograft tolerance.
...
PMID:The reversal of diabetes by pancreatic islet transplantation. 681 62

In order to study the hormonal characteristics of human prolactin-secreting pituitary adenomas, in vitro monolayer and suspension cultures from human pituitary glands were established. Optimal conditions for cultures included enzymatic dispersion into viable single-cell suspensions with the use of 1% collagenase in phosphate-buffered saline solution. After pelleting the dispersed cells by centrifugation (800 rpm for 10 minutes), they were cultured in RPMI medium that contained 20% fetal calf serum and then incubated at 37degrees C in 5% CO2. Cells were subcultured weekly at a ratio of one plate to two. In an attempt to establish whether bromocriptine has a direct inhibitory effect on pituitary secretion of prolactin (PRL), variable doses of bromocriptine were added to duplicate plates. The addition of bromocriptine to the culture medium induced suppression of PRL within 7 days. In conclusion, this study demonstrated that either monolayer of suspension cultures of human PRL secreting adenomas can be established, and that bromocriptine in doses of 1 ng/plate or more has a direct inhibitory effect on the secretion of PRL.
...
PMID:Monolayer and suspension culture of human prolactin-secreting pituitary adenoma. 743 30

The factors determining the outcome of human fetal islet transplantation in patients with insulin-dependent diabetes mellitus (IDDM) remain unclarified. In this study we analysed the ratio between immunoregulatory lymphocyte subpopulations in order to search for a possible marker of the immune destruction of transplanted islets. Human fetal islets were isolated by collagenase digestion, cultured for 14 days at 37 degrees C, 5% CO2, and implanted under fascia of m. rectus abdominis in 7 IDDM patients (5 pancreata per patient). After transplantation we evaluated simultaneously the level of metabolic control through HbA1c values determined by chromatography, the capacity of insulin secretion through the C-peptide levels (determined by radioimmunoassay) before and 6 minutes after 1 mg glucagon i.v. stimulation, and the ratio between CD4+ and CD8+ lymphocytes determined by immunofluorescence using monoclonal antibodies. We found that metabolic control after transplantation was improved together with the decrease of the insulin daily dose, and the improvement was simultaneous to the increase of both basal and glucagon-stimulated C-peptide levels. Four months after transplantation we detected a remarkable decrease in the secretion capacity, accompanied by the necessity for an increase in daily insulin dose to maintain optimal metabolic control. However, the loss of islet function was preceded by the increase in CD4+/CD8+ ratio, thus reflecting the presumable accumulation of CD4+ inducer T-lymphocytes. When the islet secretion capacity was destroyed, we found a decrease in CD4+/CD8+ ratio, reflecting the recruitment of CD8+ effector cells.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:[Human fetal pancreatic islet transplantation in insulin-dependent diabetics: possibilities of early detection of transplant destruction]. 759 Apr 18


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

---