Evaluation of a New Neural Network Classifier for Diabetic Retinopathy.

Background: Medical image segmentation is a well-studied subject within the field of image processing. The goal of this research is to create an AI retinal screening grading system that is both accurate and fast. We introduce a new segmentation network which achieves state-of-the-art results on semantic segmentation of color fundus photographs.

Comparative incorporation of proenkephalin-derived peptides, chromogranin A, and dopamine beta-hydroxylase into chromaffin vesicles.

The incorporation of enkephalin-containing peptides (ECPs) derived from proenkephalin into chromaffin vesicles was examined in primary cultures of adrenal medullary chromaffin cells. Cells were pulse-labeled with [35S]methionine and chased for periods up to 24 h. Chromaffin vesicles in cell homogenates were then fractionated by density gradient centrifugation and the presence of [35S]Met-enkephalin sequences in gradient fractions determined.

Synthesis of chromogranin A, dopamine beta-hydroxylase, and chromaffin vesicles.

Primary cultures of bovine adrenal medullary cells synthesize chromogranin A (CgA) and dopamine beta-hydroxylase (DBH) and incorporate them into chromaffin vesicles. The incorporation of L-[35S]methionine into CgA, DBH, and total protein was approximately linear for 8 h at methionine concentrations of 12.5, 25, and 50 microM.

Synthesis of alpha 2-macroglobulin by bovine adrenal cortical cell cultures.

Primary cultures of bovine adrenal medullary cells synthesize and secrete a high-molecular-weight protein into the culture medium. The protein was purified from the serum-free medium of cultured cells and was identified as alpha 2-macroglobulin by gel electrophoresis, sedimentation velocity, electron microscopy, immunoprecipitation, immunodiffusion, and autoradiography. Antisera directed against the protein were prepared and used to determine the cell types that synthesize the protein.

Effects of reserpine and tetrabenazine on catecholamine and ATP storage in cultured bovine adrenal medullary chromaffin cells.

The in vivo storage relationship between catecholamines and ATP in chromaffin vesicles of cultured bovine adrenal medulla cells was investigated using drugs that block vesicular catecholamine uptake. Three-day treatments with reserpine and tetrabenazine causing 85-90% depletion of catecholamines resulted in 41-46% reductions in cellular ATP content. Subcellular fractionation of reserpine-treated cells indicated that the ATP is lost from the chromaffin vesicle pool.

Metabolic pools of ATP in cultured bovine adrenal medullary chromaffin cells.

Cultured bovine adrenal chromaffin cells contain a pool of ATP sequestered within the chromaffin vesicles and an extravesicular pool of ATP. In a previous study it was shown that the turnover of ATP in the extravesicular pool was biphasic. One phase occurred with a t1/2 of 3.

Turnover and storage of newly synthesized adenine nucleotides in bovine adrenal medullary cell cultures.

The adenine nucleotide stores of cultured adrenal medullary cells were radiolabeled by incubating the cells with 32Pi and [3H]adenosine and the turnover, subcellular distribution, and secretion of the nucleotides were examined. ATP represented 84-88% of the labeled adenine nucleotides, ADP 11-13%, and AMP 1-3%. The turnover of 32P-adenine nucleotides and 3H-nucleotides was biphasic and virtually identical; there was an initial fast phase with a t1/2 of 3.

Relationship between the regulation of enkephalin-containing peptide and dopamine beta-hydroxylase levels in cultured adrenal chromaffin cells.

Adrenal medullary chromaffin cells were maintained under conditions known to increase their cellular levels of enkephalin-containing peptides and the effects of these treatments on another chromaffin vesicle component, dopamine beta-hydroxylase, were examined. Catecholamine-depleting drugs, such as tetrabenazine, and cyclic nucleotide-elevating drugs, including forskolin, 8-bromo-cyclic AMP, and theophylline, increase chromaffin cell enkephalin-containing peptide levels but fail to increase dopamine beta-hydroxylase. In contrast, insulin treatment increases the levels of both enkephalin-containing peptides and dopamine beta-hydroxylase.

Flux of catecholamines through chromaffin vesicles in cultured bovine adrenal medullary cells.

Primary cultures of bovine adrenal medullary chromaffin cells were pulse-labeled with [3H]dopamine or [3H]norepinephrine and examined for radioactive and total catecholamine contents by high performance liquid chromatography after additional incubations of 15 min to 10 days. [3H]Dopamine was rapidly taken up by chromaffin vesicles in situ and converted to norepinephrine with a half-time of approximately 6 h. [3H] Norepinephrine taken up by the cells was metabolized in three phases.

Visualization of the exocytosis/endocytosis secretory cycle in cultured adrenal chromaffin cells.

Cultured bovine adrenal medullary chromaffin cells were stimulated to secrete catecholamines by addition of veratridine or nicotine. The formation of an exocytotic pit exposes a major secretory granule membrane antigen, the enzyme dopamine beta-hydroxylase, to the external medium. By including antiserum to this enzyme in the medium, we were able to visualize sites of exocytosis by decoration of bound antibody using a fluorescent second antibody.

Effects of ascorbic acid, dexamethasone, and insulin on the catecholamine and opioid peptide stores of cultured adrenal medullary chromaffin cells.

Bovine adrenal medullary chromaffin cells cultured in serum-free medium were examined for changes in their catecholamine and opioid peptide stores following exposure to dexamethasone, ascorbic acid, or insulin for 2 to 12 days. Dexamethasone failed to alter cellular catecholamine levels, measured by high performance liquid chromatography with electrochemical detection, or cellular opioid peptide content, measured by an enkephalin radioreceptor assay. Chromaffin cells cultured in medium supplemented with ascorbic acid retained high ascorbate contents for 2 to 3 days, despite the rapid loss of this vitamin from the culture medium (approximately 50% lost in 2 hr).

Effects of manganese and other divalent cations on calcium uptake and catecholamine secretion by primary cultures of bovine adrenal medulla cells.

Primary cultures of bovine adrenal medullary chromaffin cells were used to examine the effect of replacing divalent cations in the extracellular media on secretion. When calcium was replaced by manganese, nicotine-stimulated secretion was delayed in onset for 3 to 5 minutes, but continued for approximately 60 minutes. In contrast, calcium-supported secretion began immediately on stimulation and plateaued by 10 minutes.

Calcium-evoked secretion from digitonin-permeabilized adrenal medullary chromaffin cells.

The effects of the steroid glycoside digitonin on cultured bovine adrenal chromaffin cells were studied as a way to gain access to the intracellular sites of calcium action in stimulus-secretion coupling. Chromaffin cells treated with digitonin secreted catecholamines by an exocytotic mechanism when exposed to free calcium concentrations of greater than 1 microM. At free calcium concentrations of less than 100 microM, an apparently saturable release of catecholamines was observed with a half-maximal effect (EC50) of 3-4 microM.

Inhibition of calcium uptake, sodium uptake, and catecholamine secretion by methoxyverapamil (D600) in primary cultures of adrenal medulla cells.

The calcium-entry antagonist D600 (methoxyverapamil) inhibited nicotine- and veratridine-induced 45Ca2+ uptake, 22Na+ uptake, and catecholamine secretion in primary cultures of bovine adrenal medulla cells. Inhibition of nicotine-induced effects occurred at D600 concentrations approximately 3-10-fold lower than those needed to produce similar inhibition of veratridine-induced effects. Inhibition of the veratridine-induced effects was competitive, but inhibition of the nicotine-induced effects was not competitive.

22Na+ uptake and catecholamine secretion by primary cultures of adrenal medulla cells.

The uptake of 22Na+ and secretion of catecholamines by primary cultures of adrenal medulla cells under the influence of a variety of agonists and antagonists were determined. Veratridine, batrachotoxin, scorpion venom, and nicotine caused a parallel increase in 22Na+ uptake and Ca2+-dependent catecholamine secretion. Ba2+, depolarizing concentrations of K+, and the Ca2+ ionophore Ionomycin stimulated secretion of catecholamines but did not increase the uptake of 22Na+.

Inhibition of 45Ca2+ uptake and catecholamine secretion by phenothiazines and pimozide in adrenal medulla cells cultures.

The inhibition by several phenothiazine drugs and pimozide of the uptake of 45Ca2+ and secretion of catecholamines by cultured adrenal medulla cells stimulated with nicotine, veratridine, 50 mM K+, ionomycin and Ba2+ was studied. The inhibition of 45Ca2+ uptake, except for ionomycin, closely parallelled the inhibition of catecholamine secretion. The nicotine-and veratridine-stimulated effects were several fold more sensitive to inhibition by the drugs than were those stimulated by 50mM K+, ionomycin and Ba2+; the ionomycin-stimulated effects were least sensitive to inhibition.

Calcium uptake and catecholamine secretion by cultured bovine adrenal medulla cells.

The uptake of 45Ca2+ and secretion of catecholamines by primary cultures of adrenal medulla cells were studied. Nicotine, veratridine, potassium, and Ionomycin stimulate both the accumulation of 45Ca2+ and the secretion of catecholamines. Nicotinic antagonists block 45Ca2+ uptake induced by nicotine, tetrodotoxin blocks 45Ca2+ uptake induced by veratridine, and D600 or secretion induced by Ionomycin.

The adrenal medulla of the diabetic mouse (C57BL/KsJ, db/db): biochemical and morphological changes.

1. Anatomic and biochemical indices of adrenal medullary function were studied in mice (Mus musculus) with hereditary mellitus (C57BL/KsJ, db/db). 2.

Inhibition of catecholamine secretion from adrenal medulla cells by neurotoxins and cholinergic antagonists.

The effects of several neurotoxins and cholinergic antagonists on the nicotine-induced secretion of catecholamines by adrenal medulla cells in culture were investigated. Aconitine, veratridine, and batrachotoxin, in the presence of 1 micrometer-tetrodotoxin inhibited the nicotine-stimulated secretion of catecholamines in a dose-dependent manner in Locke's solution. In Na+-free sucrose medium, tetrodotoxin was not required to inhibit the stimulatory effects of aconitine, veratridine, and batrachotoxin, and these agents by themselves inhibited the nicotine-stimulated secretion of catecholamines.

Phosphorylation of adrenal medulla cell proteins in conjunction with stimulation of catecholamine secretion.

Enhanced phosphorylation of two specific protein bands accompanied catecholamine secretion from cultured bovine adrenal medulla cells stimulated by different secretagogues. Cells preincubated with 32Pi were treated with nicotine, veratridine, Ionomycin, or barium. Each of these secretagogues stimulated the phosphorylation of two protein bands with apparent molecular weights of 60,000 and 95,000.

Ion channels and membrane potential in stimulus-secretion coupling in adrenal medulla cells.

The role of Na+ channels and membrane potential in stimulus secretion coupling in adrenal medulla cell cultures was investigated. Veratridine, aconitine, batrachotoxin (BTX), and scorpion venom, which increase the flux of ions through tetrodotoxin(TTX)-sensitive Na+ channels, all evoke secretion of catecholamines that is blocked by TTX. TTX partially inhibits secretion induced by low concentrations of nicotine in Locke's solution but has no effect on high concentrations of nicotine (20 microM).