Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The diagnosis of Cushing's syndrome due to "autonomous adrenocortical tumour" has been established in a patient by appropriate examinations (especially dexamethasone suppression test, ACTH stimulation test, ACTH measurement by radioimmunoassay). Isolated cells have been prepared from a piece of the tumour by a trypsin technique so that the action of ACTH on steriodogenesis in these cells could be studied in vitro. Basal production of corticosteroids by the isolated tumour cells was low (0.3 mu plus or minus 0.04/2 h/10-5 cells). Addition of ACTH induced a dose-dependent stimulation of corticosteroid production. The tumour cells appeared to be unable to produce corticosteroids in the absence of ACTH; maximal production was rather low (1.38 mu plus or minus 0.07/2 h/10-5 cells). A possible explanation for the discrepancies between endocrine function tests and the results of the in vitro studies is given.
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PMID:Dissociation of in vivo and in vitro "autonomy" in human adrenocortical tumour. 16 66

The steroidogenic response to ACTH prostaglandin E2 (PGE2) was studied in cat adrenocortical cells dispersed with trypsin. The dose-response curves of both agents were qualitatively and quantitatively similar. Exposure to PGE2 or ACTH in the presence of labeled steroid precursor (acetate) resulted in the accumulation of comparable levels of steroid intermediates and end-product. Submaximal or maximal concentrations of ACTH and PGE-2 given simultaneously elicited a response which was no greater than that obtained with either stimulant alone. Although calcium was required for optimal PGE-2 stimulation of steroid production, this requirement with ACTH as the stimulant, but greater than with butyryl cyclic AMP. PGE-2-induced increase in the adrenal cyclic AMP was not statistically significant and was small in relation to that found with equipotent steroidogenic ACTH concentrations. The possible relationship between prostaglandins, cyclic AMP, and calcium in the action of ACTH is discussed.
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PMID:Evidence for a possible prostaglandin link in ACTH-induced steroidogenesis. 16 16

Isolated adrenal cells from Vitamin E-deficient and control rats were prepared by a trypsin digestion method. Cyclic adenosine 3',5'-monophosphate (cyclic AMP) formation was studied in response to adrenocorticotropin (ACTH) in the presence and absence of ascorbate by measuring the conversion of prelabeled adenosine 5'-triphosphate [14C]ATP to cyclic [14C]AMP. Ascorbate (0.5 mM) inhibited ACTH-induced cyclic [14C]AMP formation in adrenal cells isolated from Vitamin E-deficient rats but had no effect in the control cells. The inhibitory effect of ascorbate on ACTH-induced cyclic AMP formation in Vitamin E-deficient rats decreased as the concentration of ACTH increased. In Vitamin E-deficient rats ascorbate inhibited ACTH-induced cyclic [14C]AMP formation after 30 min of incubation. There was no further significant accumulation of cyclic [14C]AMP at 60 min or 120 min although in the absence of ascorbate cyclic [14C]AMP continued to be formed. The in vitro addition of alpha-tocopherol reduced the inhibition of ACTH-induced cyclic [14C]AMP formation by ascorbate in Vitamin E-deficient rats. These studies suggest that alpha-tocopherol and ascorbate may affect ACTH-induced cyclic AMP formation through interaction with the membrane-bound enzyme adenylate cyclase.
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PMID:Effect of ascorbic acid on ACTH-induced cyclic AMP formation and steroidogenesis in isolated adrenal cells of vitamin E-deficient rats. 16 1

Prostaglandins biosynthesized from 3H-arachidonic acid by trypsin-dispersed cat adrenocortical cells were isolated by silicic acid and thin layer chromatography. PGE, PGF, and a third component with mobility properties indistinguishable from either PGA or PGB were identified both in cortical cell homogenates and incubation medium. Concentrations of ACTH (125-250 muU) which stimulate steroidogenesis enhanced the conversion of labeled precursor to all three of these prostaglandins. These findings provide further evidence for the proposal that prostaglandins function as a critical link in ACTH-induced steroidogenesis.
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PMID:ACTH-induced prostaglandin biosynthesis from 3H-arachidonic acid by adrenocortical cells. 17 81

Isolated adrenal cell preparation was used to investigate the relationship between ascorbic acid and steroidogenesis by two methods: (1) in vivo incorporation of exogenous [1-14C]ascorbic acid into endogenous ascorbic acid of adrenal by intraperitoneal injection of labeled ascorbic acid into rats and studying the depletion of labeled ascorbic acid under a variety of experimental conditions; and (2) study of the uptake of [14C]ascorbic acid by IAC in response to steroidogenic stimuli and various steroids. These studies demonstrate that: 1. IAC preparation by the trypsin digestion method results in almost total depletion of ascorbic acid from adrenal cells, i.e., ascorbic acid content of the cell preparation was less than 1% of the original ascorbic acid in quartered adrenal gland. 2. In spite of such a severe depletion of ascorbic acid, steroidogenesis in response to ACTH and dibutyryl cyclic AMP (dcAMP) is quite pronounced. 3. ACTH and dcAMP affect depletion of endogenously labeled ascorbic acid in IAC by a process that is both concentration- and time-dependent, but is independent of steroidogenic processes. 4. ACTH and dcAMP both inhibit the uptake of exogenous [1-14C]ascorbic acid, which is time-dependent but independent of the steroidogenic phenomenon. 5. The uptake of [14C]ascorbic acid by IAC is independent of extra-to-intracellular gradient of glucocorticoids or mineralocorticoids.
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PMID:Effect of steroidogenesis on ascorbic acid content and uptake in isolated adrenal cells. 17 27

Prostaglandin (PG) biosynthesis by trypsin-dispersed cat adrenocortical cells was studied by radioimmunoassay (RIA). Parallel assays of incubation media using PGF2alpha and PGF1alpha antisera established that PGF2alpha is the primary PGF released by feline cortical cells. Following the reduction of PGE to PGF with sodium borohydride (NaBH4) these same two antisera were also used to identify PGE2 as the primary PGE released. RIA using a PGE antiserum confirmed the presence of PGE in the incubation medium. Steroidogenic concentrations of ACTH (50-250muU) enhanced PGE and PGF release, and indomethacin suppressed the ACTH-facilitated release. These studies provide additional evidence for ACTH-induced PG synthesis by feline cortical cells, and support the hypothesis that PGs play some role in the steroidogenic action of ACTH.
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PMID:Radioimmunoassay measurement of ACTH-facilitated PGE2 and PGF2alpha release from isolated cat adrenocortical cells. 18 38

A 45-year-old women had medullary tyroid carcinoma associated with Cushing's syndrome and galactorrhoea. Elevated plasma immunoreactive ACTH and cortisol were partially suppressed by intravenous dexamethasone, appreciably raised by lysine vasopressin, and urinary excretion of 17-oxogenic steroids slightly elevated by metyrapone. A large arterio-venous increase in plasma corticotrophin releasing factor-like activity across the thyroid gland was observed and tumour tissue contained corticotrophin releasing factor-like activity. Biologically active ACTH was not detected in tumour extracts before incubation with trypsin, but after trypsinization a value of 3.2 mU per gram was obtained. Arterial plasma contained biologically active ACTH (1.5 mU/100 ml) prior to trypsinization. Venous effluent from the thyroid gland contained biologically active (9.6 mU/100 ml) and immunoreactive ACTH (970 pg/ml) before trypsinization. Tumour extracts also contained prolactin production-stimulating activity. These findings can explain the Cushing's syndrome and the galactorrhoea both of which disappeared completely after thyroidectomy.
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PMID:Medullary thyroid carcinoma: ectopic production of peptides with ACTH-like, corticotrophin releasing factor-like and prolactin production-stimulating activities. 18 33

Bovine adrenocortical cells dispersed by trypsin digestion of fasciculata-reticularis minces were maintained in monolayer culture for up to 6 weeks. During the first week cells grown in medium containing ACTH (1 mU/ml) secreted steroids at a rate 10 to 20-fold greater than control cultures, cortisol accounting for 80-90% of the corticotrophic response. Using tracer amounts of [3H] progesterone and [3H] pregneolone, the major products were cortisol, corticosterone, 11-deoxycortisol and 11-deoxycorticosterone in decreasing order of magnitude. After 10 to 15 days in culture steroidogenesis was no longer enhanced by ACTH. This was concomitant with an apparent loss of 11 beta-hydroxylase activity which was mainly manifested by a sharp increase in the formation of 44-deoxycortisol. Short-term incubations of these cells during the first week in culture provided evidence that steroidogenesis was related to ACTH concentrations (from 0.1 to 100 muU/ml) and stimulated by dibutyryl cyclic AMP, the corticotrophic responses being further enhanced by theophylline (0.5to 50 mumoles/5 ml). Exposure of the cells to ACTH (50 muU/ml) resulted in a rapid increase in intracellular cyclic AMP contractions concomitant with a progressive increase in the corticosteroids released into the medium.
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PMID:Preliminary observations of bovine adrenal fasciculata-reticularis cells in monolayer culture: steroidogenesis, effect of ACTH and cyclic AMP. 18 35

In light of previous studies which have implicated prostaglandin (PG) formation as a link in ACTH-induced steroid production by isolated cat adrenocortical cells, experiments were carried out to provide additional information regarding the role of PGs in adrenal steroidogenesis and their interactions with calcium and cyclic AMP. Perfusion of cat adrenal glands with Locke's solution plus beta(1-24)-ACTH resulted in an immediate increase in PGF2alpha release, which rapidly declined to basal levels after the stimulus was withdrawn. In contrast, maximal rates of steroid release were manifest some 30 min after removal of ACTH. ACTH and its onitrophenyl sulfenyl derivative (NPS-ACTH) increased PG (PGF2alpha and PGE2) and steroid release by trypsin-dispersed cat cortical cells, but NPS-ACTH, unlike ACTH, did not augment cortical cyclic AMP levels. In this same preparation, indomethacin completely blocked ACTH and NPS-ACTH facilitated PGF2alpha and PGE2 release but failed to suppress steroid release markedly. Calcium-deprivation blocked PG and steroid release evoked by these two polypeptides, and depressed PG release elicited by monobutyryl cyclic AMP (bcAMP) without affecting steroid release. These experiments offer additional evidence to support the concept that PGs play a role in the mode of action of ACTH; however, they do not appear to be obligatory intermediates in the steroidogenic process. The importance of calcium in regulating PG formation is discussed with special regard for the idea that this cation has a direct action on the enzyme systems which control PG synthesis.
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PMID:Further studies on the mechanisms controlling prostaglandin biosynthesis in the cat adrenal cortex: the role of calcium and cyclic AMP. 18 9

Monolayer cultures of trypsin-dispersed cells of the rat adenohypophysis were grown for 5 to 54 days. ACTH was localized by immunocytochemistry using an antiserum to synthetic ACTH1-28 prepared in rabbit and sheep anti-goat immunoglobulin coupled with peroxidase. ACTH content of the culture medium was measured by radioimmunoassay. Corttion time. The corticotrophs retained their essential morphological characteristics. Immunological staining was found in the secretory granules, some tubular or saccular structures, parts of the rough endoplasmic reticulum, and the cytoplasmic matrix. Immature secretory granules in the Golgi apparatus as well as some Golgi elements showed different degrees of immunoreactivity. In agreement with the high ACTH content of the culture medium the number, size and shape of the secretory granules, the active Golgi apparatus, the high amount of extragranular ACTH as well as pictures suggesting granule extrusion claim for a high ACTH synthesis and transport (and low ACTH storage) in the cultured corticotrophs.
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PMID:Corticotroph cells in primary cultures of rat adenohypophysis: a light and electron microscopic immunocytochemical study. 18 91


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