UMLS:C0011570 - FACTA Search

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Query: UMLS:C0011570 (depression)
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1. The carotid body and the carotid nerve were removed from anaesthetized cats and placed in a small Perspex channel through which Locke solution (at various pH values and usually equilibrated with 50% O(2) in N(2)) was allowed to flow. The glomus was immersed in the flowing solution while the nerve was lifted into oil covering the saline. Sensory discharges were recorded from the nerve and their frequency was used as an index of receptor activity. At times, a small segment of carotid artery, containing pressoreceptor endings, was removed together with the glomus. In this case, pressoreceptor discharges were recorded from the nerve.2. The amplitude of either chemo- or pressoreceptor discharges was not changed by strong acid solutions. Acid decreased the frequency of the baroreceptor discharges only when pH fell to less than 4.0. Solutions at low pH increased the chemosensory discharge, but acid depressed the increased chemoreceptor discharge elicited by KCl. These experiments indicated that H(+) ions probably acted as membrane ;stabilizers' without depolarizing either the nerve fibres or endings.3. Acid solutions increased the action of acetylcholine chloride (AChCl) (100-200 mug) on chemoreceptors. This effect probably was due either to inactivation of tissue cholinesterase or to enhanced sensitivity of the sensory endings to ACh.4. Choline chloride (10(-3)M), which favours ACh synthesis, protected the preparation against decay during prolonged experimentation. Hemicholinium-3 (HC-3), which blocks ACh synthesis in low concentrations (10(-5)M), depressed the chemosensory response to acid and to hypoxia when such stimuli were applied repeatedly. This concentration of HC-3 did not change effects of applied ACh.5. Substances which affect ACh release markedly changed the chemoreceptor discharge increase induced by acidity and other forms of stimulation. In the absence of Ca(2+), acid, anoxia, and interruption of flow provoked receptor depression while receptor excitation induced by ACh and KCl persisted. All stimuli excited and showed increased effectiveness as the Ca(2+) concentration was raised, but their effects declined as Ca(2+) was increased above normal values. Mg(2+) ions depressed the chemoreceptor effects induced by all these stimuli. The action of Mg(2+) was not due entirely to nerve ending block. Morphine sulphate (which decreases ACh release in other structures) also depressed the receptor response to acid and flow interruption.6. Cholinergic blocking agents such as mecamylamine, hexamethonium, atropine, dihydro-beta-erithroidine (DHE), HC-3 (10(-4)M), choline and acetylcholine (in combination with choline) depressed the effects of acid and ACh on the chemoreceptors. The effect induced by interruption of flow was depressed only by mecamylamine and DHE.7. Agents which affect the fate of released ACh, such as acetylcholinesterase and eserine salicylate, did not affect clearly the response of chemoreceptors to acid.8. The results suggest that acid stimulates chemoreceptor fibres through an indirect mechanism, viz. through increased release and/or decreased destruction of a presynaptic transmitter from the glomus cell. This transmitter is probably ACh (see following paper, Eyzaguirre & Zapata, 1968).
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PMID:Pharmacology of pH effects on carotid body chemoreceptors in vitro. 429 75

Following previous demonstration that isoproterenol stimulated and norepinephrine inhibited gastric acid secretion induced by secretagogues, role of adrenergic agonists was studied by measuring acidity the peptic activity of the effluent of the perfused rat stomach. Response of gastric secretion to isoproterenol was increased by theophylline treatment but was not affected by metiamide treatment. N6, O2'-Dibutyryladenosine 3', 5'-cyclic monophosphoric acid sodium salt monohydride (dibutyryl-c-AMP) stimulated gastric secretion in a dose-dependent manner. These results suggest the possibility that the action of isoproterenol in gastric acid secretion is mediated by c-AMP. However, gastric secretion induced by pentagastrin, histamine, or carbamylcholine was not affected by theophylline treatment. N2, O2'-Dibutyrylguanosine 3', 5'-cyclic monophosphoric acid sodium salt (dibutyryl-c-GMP) did not exert any effect on gastric secretion. Depression of pentagastrin-induced gastric secretion by norepinephrine was reversed by EGTA infusion. Moreover, Ca2+, depressed pentagastrin-induced gastric secretion. These results suggest that the action of norepinephrine is closely related to the concentration of Ca2+.
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PMID:Role of adrenergic agonists on gastric secretion in the rat. 611 Jul 14

We have previously reported that hyperosmotic solutions of sodium chloride or of xylitol possess potent anti-ulcer activity and reduce gastric acidity in the rat. They also stimulate gastric prostaglandin (PG) biosynthesis, which may bear a causal relationship to the above effects. In the present investigation we studied the effect of intragastric hyperosmolarity on the transmucosal potential difference (PD) and on the permeability to H+ ions in the rat stomach. We also studied the effect of the prostaglandin synthetase inhibitors, indomethacin and flufenamic acid, on these parameters. Rat stomach was perfused in vivo, under urethane anesthesia, by xylitol solutions made up in 0.01 N HCl. While moderately hyperosmotic (13%) xylitol was without effect, the perfusion of intensely hyperosmotic xylitol (34.5%) resulted in a long lasting reduction of the transmucosal PD from a mean (+/- SEM) of -63 +/- 4 mV to a trough value of -40 +/- 3 mV. This depression of transmucosal PD was inhibited in a dose-related fashion by prior treatment with the PG-synthetase inhibitors. Acid recovery in the effluent was significantly reduced by the 34.5% xylitol solution and indomethacin pretreatment did not modify the effect of hyperosmotic xylitol. It is concluded that, although intensely hyperosmotic xylitol produces some of the characteristic effects of a barrier breaker, i.e. depression of transmucosal PD and acid back diffusion, these two phenomena probably involve different mechanisms, as indicated by their differential response to indomethacin.
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PMID:Hyperosmotic xylitol, prostaglandins and gastric mucosal barrier. 679 43

Recent research has demonstrated the effectiveness of added fat in diets to maintain milk production and fat percent. Much of the earlier work which indicated that fat affects digestion negatively may not be applicable because of great differences in the nature of diets and fats fed and especially in total feed intake. Nevertheless, much remains to be learned about interactions of fat, fiber, calcium, and rumen microorganisms if feeding of fat is to be maximized. The uniquely high acidity in the duodenum combined with detergent action of bile acids, lysolecithin, and fatty acids causes saturated fatty acids to be more digestible in ruminants than in nonruminants. Large quantities of added dietary fat increase concentrations in plasma of very low density lipoprotein triglyceride which increases their uptake by the mammary gland with inhibition of short chain fatty acid synthesis and consequent changes in milk fatty acid composition. In some cases, secretion of milk fat is increased. Current research and practice demonstrate that 3 to 5% fat may be added to diets for lactation to increase energy intake of high-producing cows and/or to reduce starch feeding, thereby increasing the ratio of forage to concentrate to prevent depression of milk fat.
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PMID:Fat in lactation rations: review. 698 64

Cods were equipped with cannulae for drainage of the stomach and for the separate perfusion of the stomach (pure seawater containing phenol red as a volume marker) and intestine (diluted seawater). Acidity of the gastric effluence was titrated, its volume calculated from the phenol red concentration. Gastric mucosal plasma flow (MPF) was estimated by gastric 14C-aniline clearance. I.m. injection of angiotensin II (AII) depressed basal acid secretion in a dose-dependent fashion. Also the MPF was reduced, but relatively less than the secretory depression. Therefore, the AII-induced secretory inhibition could not be explained by restrained mucosal blood flow. Perfusion of the intestine with diluted seawater, or a continuous i.m. infusion of 0.6% NaCl both rendered the fishes non-drinking. A high dose of AII (150 micrograms/kg . h) induced drinking in intestinally perfused cod while lower doses (15, 50 micrograms/kg . h) did not. In i.m. saline-injected cod, all three doses were dipsogenic. The results suggest that 0.6% saline infusion induces a permanent satiety and that intestinal perfusion in addition induces a preabsorptive satiety. The preabsorptive satiety appears more resistant to the dipsogenic action of AII than the permanent one.
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PMID:Effects of exogenous angiotensin II in the Atlantic cod, Gadus morhua. Observations on gastric acid secretion, gastric sham drinking and gastric mucosal plasma flow (14C-aniline clearance). 734 2

In a retrospective study it was possible to show that of 110 cases with operative delivery, performed due to suspicious or pathological fetal blood acidity findings, 93.6% were justified. A pre-pathological or pathological umbilical cord artery pH of < 7.25 was taken as the basis for correct clinical management ("true" positive cases). There was a clear relationship between the pH of the umbilical artery blood and the clinical state of depression in the newborn. This study shows that, with the help of combined fetal supervision using cardiotocography (CTG) as a screening method and fetal blood analysis (FBA) as a method of differentiation, early stages of threatened fetal acidosis can be reliably detected without having too high a rate of operative deliveries, which must inevitably result when continuous CTG supervision is used on its own. Obstetricians should therefore try to prevent severe acidosis combined with a corresponding clinical state of depression of the newborn. This requires the use of modern monitoring (CTG and FBA) and prompt clinical measures (tocolysis or termination of labor) when the pH levels are reduced or are apparently falling.
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PMID:Indications for operative termination of labor on cardiotocography and fetal blood analysis: the reliability of these methods. 803 91

Cartilage growth and remodeling are known to be influenced by the biochemical and mechanical environment of the tissue. Previous investigators have shown that chemical factors that are relevant to mechanical loading, such as osmotic pressure and pH, induce changes in cartilage metabolism in vitro. Using a neonatal rat mandibular condyle culture system, the objectives of the work reported here were to determine (1) how the growth is influenced by osmotically applied mechanical loads; and (2) whether changes in intratissue osmotic pressure or pH cause metabolic changes in the cartilage which are then reflected by altered growth behavior. High molecular weight (MW) uncharged macromolecules polyvinylpyrrolidone (PVP) and Ficoll (presumed unable to penetrate the tissue matrix) were used to examine the effect of osmotic loading on tissue growth; concentrations corresponding to osmotic pressures of up to 100 kPa resulted in a dose-dependent depression in growth and matrix accumulation. Raffinose (which can penetrate the matrix but not the cells) had no significant effect on growth for osmotic pressures of up to 87 kPa, suggesting that compression-induced changes in intratissue osmotic pressure are unlikely to provide a signal by which cells sense and respond to mechanical compression. By contrast, changes in medium pH resulted in dose-dependent changes in growth behavior. Specifically, slight alkalinity (acidity) greatly enhanced (diminished) growth and matrix accumulation; the sensitivity to pH suggests that intratissue pH could provide a mechanism for cells to sense local glycosaminoglycan concentration and mechanical compression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of physicochemical factors on the growth of mandibular condyles in vitro. 808 55

The three-compartment model of brain acid-base regulation postulates that under circumstances of changing function or disease, hydrogen ion concentrations may differ considerably in the interstitial space (ISS), the neurons and the glial cells. During hyperglycemia plus profound ischemia, for example, direct measurements by microelectrodes followed by intracellular HRP staining show that intraglial pH can fall transiently as low as 3.9, although more often the nadir drops to the 4.5-5.5 range. Concurrently, ISS-pH and, by calculation, neuronal pH fails to and remains constant (but not necessarily the same) at pH 6.2. By contrast, during spreading depression, ISS and intraglial pH at first move rapidly and transiently in opposite directions, ISS [H+] rising, intraglial falling. These two then gradually stabilize, whereas neuronal pH remains substantially more steady and near normal, shifting only minimally from resting baseline levels over several minutes' time. Similar but less pronounced effects follow direct electrical stimulation. The net change represents complex biophysical transmembrane and buffering mechanisms that appear to guard neuronal homeostasis. Studies carried out on embryonic rat forebrain neurons and glia show that these cells have considerably different vulnerabilities to extracellular acidity depending on the anionic nature of the acid in the bathing medium. In cultures to which HCI was added to the medium, neurons and neuronal processes almost all survived ten minute exposures to pH 3.8, whereas glial cells succumbed after ten minute exposures at pH not lower than 4.2.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In vivo and in vitro control of acid-base regulation of brain cells during ischemic and selective acidic exposure. 842 56

Incubation of cultured hippocampal slices with chloroquine, a compound that increases the pH of acidic subcellular organelles, for 10 h reduced the activity of cathepsin L by 83 +/- 0.87% (mean +/- s.e.m.) while only marginally suppressing cathepsin B. This effect was followed within 3 h by an increase in the concentration of mature, single-chain cathepsin D (up 61 +/- 28%). Selective depression of cathepsin L with N-CBZ-L-phenylalanyl-L-phenylalanine-diazomethylketone also resulted in increases in enzymatically active cathepsin D and the delayed appearance of a 29 kDa fragment of the tau protein. These findings demonstrate that the pattern of cathepsin L, B, and D changes found in the aged brain can be reproduced by reducing the acidity of the lysosomal milieu. They also indicate that such pH shifts initiate a sequence of linked disturbances (inactivation of cathepsin L > induction of cathepsin D > aberrant tau proteolysis) likely to play an important role in brain ageing.
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PMID:Selective suppression of cathepsin L results from elevations in lysosomal pH and is followed by proteolysis of tau protein. 967 99

The processing technology and characteristics of orubisi/amarwa, an opaque beer commonly consumed in Kagera region in the north-western part of Tanzania is described in detail. The protein content of orubisi increased from 2.0 to 2.7% after 120 hours of fermentation. The maximum alcohol content of orubisi as determined by specific gravity method was 2.5%. The alcohol profile of orubisi analysed by gas liquid chromatography (GLC) was found to contain ethanol and iso-butanol. The test for methanol was negative. Orubisi was characterised as product with relatively high acidity ranging from 0.35-0.89 g/100 ml and a final pH of 3.7. The levels of fermentable sugars--sucrose, maltose, glucose and fructose--were 0.5, 0.7, 1.8 and 0.6 g/100 ml after 120 hours of fermentation, respectively. High microbial counts were encountered in orubisi. The viable counts included yeasts: 2.0 x 10(7) cfu/ml, moulds 7.4 x 10(6) cfu/ml, coliforms 1.18 x 10(2) cfu/ml, lactic acid bacteria 6.5 x 10(7) cfu/ml and total aerobic count 2.95 x 10(7) cfu/ml. Based on these results, orubisi poses a serious danger to public health due to the presence of high numbers of total count and coliforms. In order to improve the safety of orubisi the pasteurisation step is recommended in the process of preparing orubisi. Hygienic handling of the final product is necessary in order to avoid contamination before consumption. The presence of trace amount of iso-butanol can lead to irritation of mucous membranes and depression of central nervous system.
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PMID:Aspects of manufacture, composition and safety of orubisi: a traditional alcoholic beverage in the north-western region of Tanzania. 1110 5

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