Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to investigate whether platelet-activating factor (PAF), PAF receptors, and PAF receptor-mediated effects in the human myocardium play a role in cardiac depression during anaphylaxis or septic shock. The effects of PAF, the biologically inactive derivative lyso-PAF, and the specific PAF antagonist WEB 2086 were studied in human myocardial tissue, in human coronary arteries, in human platelets, and in human lung tissue. PAF (C16-PAF, C18-PAF; 0.000001 to 1 mumol/L) had no effect on isometric force of contraction of electrically driven right atrial trabeculae (patients undergoing aortocoronary bypass surgery) and left ventricular papillary muscle strips (mitral valve replacement). PAF (0.2 mumol/L) did not influence the concentration-response curve of either the beta-adrenoceptor agonist isoprenaline (ISO, 0.0001 to 1 mumol/L) or the m-cholinoceptor agonist carbachol (CARB, 0.0001 to 10 mumol/L). The effectiveness (ISO +4.7 +/- 0.7 mN, PAF + ISO + 4.3 +/- 0.44 mN, CARB -2.7 +/- 1.06 mN; PAF + CARB -2.6 +/- 0.52 mN) and the potency--as indicated by the EC50 values--of both isoprenaline and carbachol were identical with and without pretreatment with PAF (0.2 mumol/L). PAF at concentrations of 0.000001 to 10 mumol/L exerted no effect on force of contraction either precontracted (prostaglandin F2 alpha, 0.3 mumol/L) or unprecontracted in human coronary artery rings. Histamine (0.01 to 100 mumol/L) and noradrenaline (0.001 to 30 mumol/L) initiated concentration-dependent contraction in human coronary artery rings (EC50: histamine, 1.86 mumol/L; noradrenaline, 0.69 mumol/L). At lower concentrations (PAF, 0.01 mumol/L) PAF produced complete aggregation of human platelets. In human platelet membranes and lung membranes, 3H-WEB 2086 exhibited saturable high-affinity binding (KD 14.4 nmol/L and 14.3 nmol/L). The maximal binding capacity was 292 fmol/mg protein and 268 fmol/mg protein, respectively. In displacement experiments PAF (0.01 to 10000 nmol/L) and WEB 2086 (0.01 to 10000 nmol/L), but not lyso-PAF, completely displaced 3H-WEB 2086 from its binding sites on human and lung membranes. In contrast, neither in left ventricular membranes nor in right atrial membranes was specific binding of 3H-WEB 2086 observed. These results suggest that there are neither specific PAF receptors nor direct PAF-mediated actions in human myocardial tissue or human coronary artery rings. The effects of PAF on myocardial function may be due to the activation of mediators (e.g., histamine).
 ...
PMID:Existence of PAF receptors in human platelets and human lung tissue but not in the human myocardium. 132 30

Intraindividual comparisons of diets supplemented with sunflowerseed oil (rich in linoleic acid, LA, C18:2n-6), linseed oil (enriched with alpha-linolenic acid, LNA, C18:3n-3) and canned mackerel (rich in eicosapentaenoic acid, EPA, C20:5n-3 and docosahexaenoic acid, DHA, C22:6n-3) were made in 30 patients with primary hyperlipoproteinemia (HLP) of phenotypes IIa (n = 9), IIb (n = 7), IV (n = 7) and V (n = 7). The lipid- and blood pressure-lowering effects of polyunsaturated fatty acids (PUFA), particularly those of the EPA- and DHA-rich diet, were confirmed irrespective of the type of HLP. Apolipoproteins A-I and B remained unchanged. The most remarkable finding was a substantial depression of free fatty acids (FFA) within a standardized glucose tolerance test (GTT) associated with the fall of serum triglycerides after diets enriched with n-6 and especially after those supplemented with n-3 PUFA. It was suggested that the decrease of FFA indicates reduced peripheral lipolysis, which might be a hitherto ignored factor involved in the triglyceride-lowering action of n-6 and, more pronounced, of n-3 PUFA.
 ...
PMID:A possible contribution of decrease in free fatty acids to low serum triglyceride levels after diets supplemented with n-6 and n-3 polyunsaturated fatty acids. 214 66

Plasma and urine levels of an endogenous digitalis-like compound (EDLC) are increased in low renin Na+-dependent experimental hypertension, in some normotensive offspring of hypertensive patients and in some essential hypertensive patients. Urine-drived EDLC was purified from 550 L of urine from essential hypertensive patients (n = 8) and from normotensive subjects with a family history of hypertension (n = 27), using flash chromatography on C18 reversed-phase, anion exchange chromatography and various reversed-phase high performance liquid chromatographies. The mechanism of Na+-K+ ATPase inhibition and the related effects of semipurified urine-derived EDLC were studied and compared with those of ouabain. Its action was similar to that of ouabain in 8 out of 10 of the tests applied. The main effects of such a compound were the depression of Na+-K+ pump activity of human erythrocytes, the inhibition of 5-hydroxytryptamine reuptake by human platelets, and the induction of natriuresis in urethanized rats. Therefore, EDLC may be considered as one of the natriuretic hormones whose mechanism of action closely resembles that of ouabain.
 ...
PMID:An endogenous digitalis-like compound extracted from human urine: biochemical and chemical studies. 282 38

An inhibitor of hepatic uroporphyrinogen decarboxylase (EC 4.1.1.37) was demonstrated in heat-treated extracts of livers from C57BL/10ScSn mice with iron overload after a single dose (100 mg/kg; 350 mumol/kg) of hexachlorobenzene (HCB). Inhibition was not due to accumulated uroporphyrin since this could be removed by a SEP-PAK C18 cartridge without affecting inhibitor activity. The presence of the inhibitor could be first demonstrated 2 weeks after mice received HCB and before major elevation of hepatic porphyrin levels. Maximum inhibitory potential was reached at about 8 weeks and was still detected 25 weeks after the chemical, thus paralleling the depression of enzyme activity reported previously [Smith, Francis, Kay, Greig & Stewart (1986) Biochem. J. 238, 871-878]. The inhibitor was not detected following treatment of mice with either iron or HCB alone or after the decarboxylase activity was destroyed in vitro by the combination of uroporphyrin and light. The formation of the inhibitor by inbred mouse strains nominally Ah-responsive (C57BL/6J, C57BL/10ScSn, BALB/c, C3H/HeJ, CBA/J and A/J) and Ah-nonresponsive (SWR, AKR, 129, SJL, LP and DBA/2) did not correlate fully with their reported Ah-phenotype. There was a correlation amongst the Ah-responsive strains only, with hepatic ethoxyphenoxazone de-ethylase activity induced in parallel experiments by treatment with beta-naphthoflavone. De-ethylase activity induced by HCB, however, was considerably less than that with beta-naphthoflavone, which has not been reported as porphyrogenic. Other polyhalogenated chemicals, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,4,2',3',4'-hexachlorobiphenyl and hexabromobenzene, also caused the formation of the inhibitor of uroporphyrinogen decarboxylase.
 ...
PMID:Chemically-induced formation of an inhibitor of hepatic uroporphyrinogen decarboxylase in inbred mice with iron overload. 367 56

Emulsions of C18 unsaturated fatty acids (FA) were infused for 2 h into the intestine of conscious sheep while motility of the reticulum and rumen was recorded. Statistically-significant depression of motility was found when 3 or 5 g FA/h were infused. At 1 g/h there were minor disruptions of motility. The inhibitory potency was not related to the extent of unsaturation of the FA. Receptors mediating the inhibitory effect were postulated to be distal to the iliac flexure of the duodenum, but the possible role of bile and pancreatic juice is discussed in relation to this problem. The probability that the effect was hormonally mediated is discussed.
 ...
PMID:The inhibitory effect of intestinal infusions of unsaturated long-chain fatty acids on forestomach motility of sheep. 641 Nov 15

The interrelationships of dietary vitamin E and essential fatty acids and their effects on serum and pulmonary prostaglandin (PG) synthesis and fatty acid precursors were examined. In a preexperimental period, male weanling rats were depleted of essential fatty acids (EFA) by feeding on a hydrogenated coconut oil diet. At the end of 45 days, average serum triene:tetraene ratio for the EFA-deficient rats was 0.76. After a refeeding period with a 20% safflower oil diet and 0, 1 or 50 mg of dl-alpha-tocopheryl acetate daily, serum and pulmonary fatty acid profiles and PG synthesis were determined. A trend to growth depression on the high vitamin E diet was observed. Vitamin E supplementation seemed to have no significant effect on fatty acid composition or synthesis of PGE1, PGE2, PGF2 alpha or PGI2 in lung. This may be due to the small lipid content and presumed inability of lung to accumulate excess vitamin E. Lung may, therefore, be resistant to such dietary manipulations. Serum PG synthesis was not affected by vitamin E dose, although the C20:4 omega 6/C18:2 omega 6 ratio in serum was significantly lowered on the high vitamin E diet.
 ...
PMID:Effects of dietary vitamin E on serum and pulmonary fatty acids and prostaglandins in rats fed excess linoleic acid. 672 76

Data were pooled from 11 studies evaluating supplemental fat sources differing primarily in degree of saturation (tallow, animal-vegetable fat, vegetable oil, and hydrogenated fats). Data were standardized as proportions of the respective controls to reduce variation among individual studies and were subjected to stepwise multiple regression against the iodine value of fats, the percentage increases of total fatty acids in diets above the respective controls, or the ratio of total C16 to C18 fatty acids in fats (only for hydrogenated fats). Increased iodine value (increasing unsaturation) of fats increased apparent fatty acid digestibility, especially as iodine value increased from 11 to 27. For partially hydrogenated fat sources, as the ratio of C16 to C18 fatty acids increased, digestibility also increased, especially with increasing iodine value (positive interaction). Beneficial effects of higher C16:C18 ratio were reduced as amount of added fat increased (negative interaction). Dry matter intake and FCM production decreased as iodine value increased, perhaps because of inhibition of fiber digestion or metabolic regulation of DMI. Milk protein percentage depression averaged .2 percentage units for most fats. However, as partially hydrogenated fat sources became more saturated, milk protein depression appeared to be less evident; increased ratio of C16:C18 of fatty acids appeared to increase milk protein percentage. Despite the lower apparent digestibility of fatty acids of hydrogenated fats, increased milk production and percentages of fat and protein appeared to make them more economical than more unsaturated fats.
 ...
PMID:Assessment of the effects of iodine value on fatty acid digestibility, feed intake, and milk production. 796 57

The role of trans-C18:1 fatty acids in milk fat depression was examined. Six rumen-cannulated Holstein cows were assigned to two Latin squares with 21-d periods. The common basal diet contained 40% forage and 60% concentrate. Treatments were the uninfused control, 750 g/d of a mixture of cis fat (65% high oleic sunflower oil and 35% cocoa butter), and 750 g/d of a mixture of trans fat (93% shortening and 7% corn oil) infused into the abomasum via a tube that passed through the rumen cannula. Milk yield was similar among treatments. Milk fat percentage and yield were lower, and milk citrate concentration was higher, for the trans than the cis treatment. Changes in the fatty acid composition of milk were similar for the cis and trans treatments compared with the control except for trans-C18:1. The concentration of trans-C18:1 was greater for the cis and trans treatments than for the control and was greater for the trans than for the cis treatment. These data clearly demonstrated that infusion of trans-C18:1 fatty acids into the abomasum depressed milk fat percentage and yield. We speculate that reduced synthesis of fatty acids and reduced activity of acyl transferase in mammary tissue contributed to depressed milk fat percentage for the trans treatment.
 ...
PMID:Milk fat yield and composition during abomasal infusion of cis or trans octadecenoates in Holstein cows. 812 Jan 84

Metabolic and endocrinological characteristics were compared for cows that differed in the extent of milk fat depression. Forty-one multiparous Holstein cows were fed control (40% concentrate and 60% forage) and high concentrate (80% concentrate and 20% forage) diets in a doubale-reversal design. Cows showing one or more percentage units of depression in milk fat were arbitrarily classified as responders (n = 26); those remaining were classified as nonresponders (n = 15). Compared with nonresponders, responders had greater increases in DMI, estimated NEL intake and balance, BW, milk yield, protein and lactose yields in milk, weight percentage of trans-C18:1 fatty acids in milk, and concentrations of triiodothyronine and thyroxine in serum when switched from the control diet to the 80% concentrate diet. Lack of an increase in concentrations of glucose and insulin in serum of cows with the greatest decline in percentage of milk fat casts doubt on the ability of the glucogenic theory to explain milk fat depression completely.
 ...
PMID:Milk fat depression, the glucogenic theory, and trans-C18:1 fatty acids. 855 Sep 10

Milk fat depression in cows fed high grain diets has been shown to be related to increased trans-C18:1 fatty acids in milk. Trans-C18:1 fatty acids are produced as a result of incomplete biohydrogenation of dietary polyunsaturated fatty acids in the rumen. The objective of this study was to determine the effects of varying amounts of dietary concentrate and buffer addition on duodenal flow, apparent absorption, and incorporation of trans-C18:1 fatty acids into milk fat. Four ruminally and duodenally cannulated multiparous Holstein cows in midlactation were fed diets consisting of 60% (high) or 25% (low) forage with or without buffer (1.5% NaHCO3 and 0.5% MgO). Treatments were arranged in a 2 x 2 factorial within a 4 x 4 Latin square design. The diet containing low forage and no buffer increased the flow of trans-C18:1 fatty acids to the duodenum compared with the effects of other diets (120 vs. 57 to 66 g/d). Ruminal pH was lower for cows fed the low forage diets. The addition of buffer increased ruminal pH by 0.19 and 0.02 units for cows fed the low forage and high forage diets, respectively. Cows fed the diet containing low forage and no buffer produced milk with a lower fat percentage. The addition of buffer to the low forage diet partially corrected milk fat depression. Milk trans-C18:1 fatty acids were higher for cows fed the low forage diet without buffer than for cows fed the other diets (5.8% vs. 3.0%). Altered ruminal function resulting from low ruminal pH for cows fed the low forage diet and no buffer may play a role in the increased production of trans-C18:1 fatty acids in the rumen.
 ...
PMID:Effect of dietary forage concentration and buffer addition on duodenal flow of trans-C18:1 fatty acids and milk fat production in dairy cows. 931 53


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