Biomedical subjects

Y Y Yeh

Publications and source records attributed to Y Y Yeh.

At least 19 recordsLinked to original sources

PubMed2001

Water-soluble organosulfur compounds of garlic inhibit fatty acid and triglyceride syntheses in cultured rat hepatocytes.

The putative hypolipidemic effect of garlic remains controversial. To gain further insight into the effect of garlic on lipid metabolism, the present study determined the inhibitory effects of water-soluble organosulfur compounds present in garlic on triglyceride (TG) and fatty acid synthesis in cultured rat hepatocytes. When incubated at 0.05 to 4.0 mmol/L with cultured hepatocytes, S-allyl cysteine (SAC) and S-propyl cysteine (SPC) decreased [2-14C]acetate incorporation into triglyceride in a concentration-dependent fashion achieving a maximal inhibition at 4.0 mmol/L of 43 and 51%, respectively. The rate of [2-14C]acetate incorporation into phosphlipids was depressed to a similar extent by SAC and SPC. SPC, SAC, S-ethyl cysteine (SEC), and gamma-glutamyl-S-methyl cysteine decreased [2-14C]acetate incorporation into fatty acid synthesis by 81, 59, 35, and 40%, respectively, at 2.0-4.0 mmol/L concentrations. Alliin, gamma-glutamyl-S-allyl cysteine, gamma-glutamyl-S-propyl cysteine S-allyl-N-acetyl cysteine, S-allylsulfonyl alanine, and S-methyl cysteine had no effect on fatty acid synthesis. The activities of lipogenic enzymes, fatty acid synthase (FAS), and glucose-6-phosphate dehydrogenase (G6PDH) were measured in cultured hepatocytes treated with the inhibitors. The activity of FAS in cells treated with 4.0 mmol/L SAC and SPC, respectively, was 32 and 27% lower than that of nontreated cells. Neither SAC nor SPC affected G6PDH activity. The results indicate that SAC, SEC, and SPC inhibit lipid biosynthesis in cultured rat hepatocytes, and further suggest that these S-alk(en)yl cysteines of garlic impair triglyceride synthesis in part due to decreased de novo fatty acid synthesis resulting from inhibition on FAS. Whether tissue concentrations of active garlic components can achieve levels required to inhibit TG synthesis in vivo warrants further investigation.

Acetates↗

PubMed2001

Feasibility and potential benefit of maintenance endoscopic variceal ligation in patients with unresectable hepatocellular carcinoma and acute esophageal variceal hemorrhage: a controlled trial.

BACKGROUND: Patients with unresectable hepatoma and acute esophageal variceal bleeding have extremely high rates of recurrent bleeding and mortality. This controlled study evaluates the feasibility and potential benefit of maintenance endoscopic variceal ligation in these patients. METHODS: Patients with unresectable hepatoma and acute esophageal variceal bleeding underwent emergent endoscopic variceal ligation. After hemostasis, patients were randomized to undergo maintenance or esophageal variceal ligation (EVL) as necessary (demand ligation). RESULTS: Fifty-four patients underwent maintenance EVL and 55 demanded EVL. One or more subsequent EVL session could be performed in only 30 patients (55.6%) in the maintenance group (actual maintenance ligation). Logistic regression analysis found that hepatic function determines the feasibility of maintenance ligation (Child-Pugh's A+B vs. C, OR 23.00: 95% CI [5.26, 100.66]). The survival and recurrent bleeding rates were similar in both groups. A subgroup analysis of patients with Child-Pugh's A and B hepatic reserve in both the maintenance EVL group (n = 24) and demand EVL group (n = 25) was performed to assess the potential benefit of maintenance ligation. Maintenance ligation reduced the rate of recurrent bleeding compared with demand ligation (p = 0.043). Cox regression showed that portal vein thrombosis and tumors in both hepatic lobes were also factors together with EVL that determined recurrence of bleeding. Survival was similar in both groups. CONCLUSIONS: Maintenance ligation is feasible in patients with unresectable hepatoma and variceal hemorrhage if they have a good hepatic reserve. Maintenance ligation might lower the rate of recurrent bleeding in this subgroup of patients.

Acute Disease↗

PubMed2001

The emission characteristics of a small D.I. diesel engine using biodiesel blended fuels.

Biodiesel and biodiesel blends provide low emissions without modification on the fuel system of conventional diesel engines. This study aims to develop a new domestic biodiesel production procedure which makes use of waste fryer vegetable oil by transesterification method, and further investigates the emission characteristics of a small D.I. diesel engine using biodiesel blends and diesel fuels, respectively. The 20/80 and 30/70 blends of biodiesel to diesel fuel are used in this study. The emission characteristics include smoke emissions, gaseous emissions (CO, HC, NOx and SO2), particle size distributions and number concentrations at a variety of steady state engine speed points. We have found that diesel engine fueled with biodiesel blends emits more PM2 particle number concentrations than those with diesel fuel, and PM2 number concentration increases as biodiesel concentration increases. As for the smoke and gaseous emissions, such as CO, HC, NOx and SO2, the results favored biodiesel blends.

Air Pollutants↗

PubMed2001

Cholesterol-lowering effect of garlic extracts and organosulfur compounds: human and animal studies.

The medicinal use of garlic dates back thousands of years, but there was little scientific support of its therapeutic and pharmacologic properties until recently. In the past decade, the cancer-protective effects of garlic have been well established by epidemiologic studies and animal experiments. However, the cardiovascular-protective properties of garlic are less well understood. In particular, despite the reported hypocholesterolemic effect of garlic, the mechanism of the effect is unclear. In a recent randomized, double-blind, placebo-controlled intervention study, we showed that aged garlic extract (AGE) supplementation was effective in lowering plasma concentration of total cholesterol by 7% and LDL cholesterol by 10% in hypercholesterolemic men compared with subjects consuming a placebo. Supplementation of AGE in animal diets similarly reduced plasma concentrations of total cholesterol and triacylglycerol by 15 and 30%, respectively. In subsequent experiments using cultured rat hepatocytes, we found 44--87% inhibition of cholesterol synthesis by the water-extractable fraction (WEF), methanol-extractable fraction (MEF) and petroleum ether-extractable fraction (PEF) of fresh garlic, and Kyolic (liquid form of AGE). These observations suggested that hydrophilic and hydrophobic compounds of garlic are inhibitory to cholesterol synthesis. Because S-allylcysteine (SAC) alone was less potent than Kyolic, which contains SAC and other sulfur compounds, a maximal inhibition appears to require a concerted action of multiple compounds of garlic. In a series of experiments, we further characterized the inhibitory potency of individual water-soluble and lipid-soluble compounds of garlic. Among water-soluble compounds, SAC, S-ethylcysteine (SEC), and S-propylcysteine (SPC) inhibited cholesterol synthesis by 40--60% compared with 20--35% by gamma-glutamyl-S-allylcysteine (GSAC), gamma-glutamyl-S-methylcysteine (GSMC) and gamma-glutamyl-S-propylcysteine (GSPC). Lipid-soluble sulfur compounds (i.e., diallyl sulfide, diallyl disulfide, diallyl trisulfide, dipropyl sulfide and dipropyl trisulfide) at low concentrations (0.05--0.5 mol/L) slightly (10--15%) inhibited cholesterol synthesis but became highly cytotoxic at high concentrations (1.0--4.0 mol/L). All water-soluble compounds, except S-allylmercaptocysteine, were not cytotoxic, judging from the release of cellular lactate dehydrogenase into the culture medium. Taken together, the results of our studies indicate that the cholesterol-lowering effects of garlic extract, such as AGE, stem in part from inhibition of hepatic cholesterol synthesis by water-soluble sulfur compounds, especially SAC.

Animals↗

PubMed2000

Inhibition of cholesterol biosynthesis by organosulfur compounds derived from garlic.

The study was undertaken to test the inhibitory potential on cholesterogenesis of organosulfur compounds derived from garlic. The primary rat hepatocytes maintained in Dulbecco's modified Eagle's medium were treated with [2-14C]acetate as substrate for cholesterol synthesis in the presence or absence of test compounds at 0.05 to 4.0 mmol/L. Eleven water-soluble and six lipid-soluble compounds of garlic were tested. Among water-soluble compounds, S-allyl cysteine (SAC), S-ethyl cysteine (SEC), and S-propyl cysteine (SPC) inhibited [2-14C]acetate incorporation into cholesterol in a concentration-dependent manner, achieving 42 to 55% maximal inhibition. Gamma-glutamyl-S-allyl cysteine, gamma-glutamyl-S-methyl cysteine, and gamma-glutamyl-S-propyl cysteine were less potent, exerting only 16 to 29% maximal inhibitions. Alliin, S-allyl-N-acetyl cysteine, S-allylsulfonyl alanine, and S-methyl cysteine had no effect on cholesterol synthesis. Of the lipid-soluble compounds, diallyl disulfide (DADS), diallyl trisulfide (DATS), and dipropyl disulfide (DPDS) depressed cholesterol synthesis by 10 to 25% at low concentrations (< or =0.5 mmol/L), and abolished the synthesis at high concentrations (> or =1.0 mmol/L). Diallyl sulfide, dipropyl sulfide, and methyl allyl sulfide slightly inhibited [2-14C]acetate incorporation into cholesterol only at high concentrations. The complete depression of cholesterol synthesis by DADS, DATS, and DPDS was associated with cytotoxicity as indicated by marked increase in cellular LDH release. There was no apparent increase in LDH secretion by water-soluble compounds except S-allyl mercaptocysteine, which also abolished cholesterol synthesis. Judging from maximal inhibition and IC50 (concentration required for 50% of maximal inhibition), SAC, SEC, and SPC are equally potent in inhibiting cholesterol synthesis.

Acetates↗

PubMed2000

The conception of depression in Chinese American college students.

The conception of depression in Chinese American college students was examined with the Center for Epidemiologic Studies--Depression Scale (CES-D). It was hypothesized that, because of their significant engagement with mainstream American culture, these students' conception of depression would better approximate White Americans' differentiated view (L. Radloff, 1977) than the general Chinese American community's integrated view (Y. Ying, 1988). A total of 353 bicultural Chinese American college students participated in the study. Consistent with the hypothesis, principal-components factor analysis with varimax rotation revealed a factor structure and loading similar to that found in White American adults. Confirmatory factor analysis also showed Chinese American college students to better approximate Radloff's differentiated model based on her White American samples than Ying's integrated model based on her Chinese American community sample. Implications of the findings and directions for future research are discussed.

Acculturation↗

PubMed1999

Dietary supplementation with arachidonic and docosahexaenoic acids has no effect on pulmonary surfactant in artificially reared infant rats.

Despite the potential use of long chain polyunsaturated fatty acid (LCPUFA) supplementation to promote growth and neural development of the infant, little is known about potential harmful effects of the supplementation. The present study determined whether supplementation with arachidonic acid (AA) and/or docosahexaenoic acid (DHA) in rat milk formula (RMF) affects saturation of pulmonary surfactant phospholipids (PL). Beginning at 7 d of age, infant rats were artificially fed for 10 d with RMF supplemented with AA at 0, 0.5, and 1.0% of total fatty acid, or supplemented with DHA at 0, 0.5, and 1.0%, or cosupplemented with AA and DHA at levels of 0:0, 0.5:0.3, and 1.0:0.6% of the fat blend. Lung tissue PL contained 43 weight percent palmitate (16:0) of total fatty acids in infant rats fed the unsupplemented RMF. The supplementation with AA at both 0.5 and 1.0% decreased the weight percentage of 16:0 and stearate (18:0), indicating a decrease in saturation of PL. The observed decreases were accompanied by increases in AA and linoleic acid (18:2n-6). Surfactant phosphatidylcholine (PC) consisted of 71 weight percent 16:0 in the unsupplemented group, and this highly saturated PC was not altered by the cosupplementation with AA and DHA although there was a slight increase in DHA. Similarly, the cosupplementation did not change fatty acid composition of surfactant PL when compared with the unsupplemented group. The cosupplementation slightly decreased the weight percentage of 16:0 with a proportional increase in 18:0 leading to an unchanged weight percentage of total saturated fatty acids. These results suggest that, unlike lung tissue PL, the composition of saturated fatty acids in surfactant PL, particularly PC, is resistant to change by dietary AA and DHA supplementation. This, together with the unchanged concentration of total fatty acids in surfactant PC, indicates that LCPUFA cosupplementation causes no effect on pulmonary surfactant.

Animals↗

PubMed1999

[The study of family structure, illness symptom, and stress adaptation of psychotic patients].

The major purposes of this paper are to explore the phenomena of family structure, illness symptoms, family coping and adaptation for patients with schizophrenia or manic-depression psychosis. This paper tries to provide a good reference instrument for application by nurses in home care, in order to understand and evaluate family needs. Subjects are schizophrenic or manic-depression outpatients from 3 hospitals located in northern Taiwan. Data were collected through home interview with primary caregivers and observations. There were fifty subjects from each of the 3 hospitals, and 151 subjects in total. Descriptive statistics, t-test, one way ANOVA, Pearson correlation and multiple stepwise correlation were used to analyze data. Research indicates that most patients are aged between 31 to 40, with over 10 years elapsed since onset, and are not married. Most primary caregivers are parents over 60 years old. Most family development was at the stage with young adult offspring. The manic-depressive patients have more working opportunities than schizophrenic patients. For schizophrenic patients, paranoia was the most serious in active symptoms; lack of interpersonal interaction was the most serious in negative symptoms; the other major problem was sleep disturbance in emotion-behavior assessment. Patient's disposition was the most concerning issue for families and the worst coping efficiency occurred with lazy behavior and sleep disturbance. For manic-depressive patients, aggressive behavior was the most serious active symptom, lack of energy was the most serious in negative symptom, and sleep disturbance was the most concerning problem in emotion-behavior assessment. The patient's symptom was the most concerning issue for families and the worst coping efficiency was found in drug side effect. The result also indicates that active and negative symptoms are both related to coping efficiency.

Adaptation, Psychological↗

PubMed1998

Modification of milk formula to enhance accretion of long-chain n-6 and n-3 polyunsaturated fatty acids in artificially reared infant rats.

Artificially reared infant rats were used to determine the effects of long-chain polyunsaturated fatty acid (LCPUFA) supplementation on blood and tissue concentrations of arachidonic acid (AA) and docosahexaenoic acid (DHA). Beginning at 7 d of age, infant rats were fed for 10 d with rat milk formulas supplemented with AA at 0, 0.5 and 1.0%, or supplemented with DHA at 0, 0.5 and 1.0% of total fatty acid. The supplementation of AA increased accretion of the fatty acid in tissue and blood phospholipids with a maximum increase of 9% in brain, 15% in liver, 25% in erythrocytes, and 43% in plasma above the values of unsupplemented infant rats. Rat milk formula containing 1.0% of AA had no added benefits over that containing 0.5% of AA. The supplementation of DHA increased phospholipid DHA by a maximum of 24% in brain, 87% in liver, 54% in erythrocytes, and 360% in plasma above the unsupplemented control. The increase in tissue and blood DHA was concentration-dependent on formula fatty acid. Brain phosphatidylcholine and phosphatidylethanolamine were similarly enriched with AA and DHA by supplementation of the corresponding fatty acids. In general the observed increase of AA was accompanied by a decrease in 16:0, 18:1 n-9, and/or 18:2n-6, whereas the increased DHA was associated with a reduction of 18:1n-9, 18:2n-6, and/or 20:4n-6. Clearly, infant rats were more responsive to DHA than AA supplementation, suggesting a great potential of dietary manipulation to alter tissue DHA concentrations. However, the supplementation of DHA significantly decreased tissue and blood AA/DHA ratios (wt%/wt%), whereas there was little or no change in the ratio by AA supplementation. Although the physiological implications of the levels of AA and DHA, and AA/DHA ratios achieved under the present experimental conditions are not readily known, the findings suggest that artificial rearing could provide a suitable model to investigate LCPUFA requirements using various sources of AA and DHA in rats.

Animals↗

PubMed1998

Case report: successful obliteration of a bleeding duodenal varix using endoscopic ligation.

The occurrence of duodenal varices is rare and experience in the control of haemorrhage from duodenal varices is limited. A 69-year-old man with hepatocellular carcinoma presenting with upper gastrointestinal bleeding is reported. Emergency upper gastrointestinal endoscopy indicated one varix 1.5 cm in diameter with white nipple sign at the anterior wall of the duodenal bulb. Endosonography confirmed the diagnosis of duodenal varix. The patient was treated with endoscopic ligation and follow-up endoscopy showed complete eradication of duodenal varix 3 weeks later.

Aged↗

PubMed1997

Stearic acid modifies very low density lipoprotein lipid composition and particle size differently from shorter-chain saturated fatty acids in cultured rat hepatocytes.

Stearic acid as compared to myristate, palmitate, or oleate is poorly incorporated into triacylglycerol, a major lipid component of very low density lipoprotein (VLDL). The present study investigated the effects of these fatty acids on VLDL metabolism in cultured rat hepatocytes. All fatty acids stimulated [2-3H] glycerol incorporation into VLDL lipids and secretion of [3H]-labeled VLDL by hepatocytes. However, the rate of [3H]-labeled VLDL secretion in the presence of nonlabeled stearate (12.8 +/- 0.7 pmol/mg protein/4 h) was 46, 59, and 22% of that observed for those treated with myristate, palmitate, and oleate, respectively. [1-14C]Stearate as a substrate was also less effective than other labeled fatty acids to be incorporated into VLDL lipids. Of total VLDL lipids synthesized from [1-14C] stearate, triacylglycerol accounted for 78% as compared to 88-97% of that derived from palmitate, myristate, and oleate. The amounts of apoB100 and apoB48 were the same in hepatocytes treated with or without exogenous fatty acids. Similarly, the rate of apoB synthesis from [35S] methionine was not affected by exogenous fatty acids. The treatment of cells with various saturated fatty acids increased the particle size of VLDL to different extents. The largest particles of VLDL, with a mean diameter of 79.3 +/- 11.9 nm, were seen in the cells treated with stearate, followed by those treated with palmitate and myristate (45.5 +/- 9.8 and 38.6 +/- 6.8 nm, diameter, respectively). Clearly, hepatocytes treated with stearate secrete less VLDL and produce larger VLDL particles than those treated with shorter-chain saturated fatty acids.

Animals↗

PubMed1997

Desaturation of stearate is insufficient to increase the concentrations of oleate in cultured rat hepatocytes.

Desaturation of stearate and palmitate and its effect on cellular accumulation of oleate were determined in primary culture of rat hepatocytes. The rate of oleate synthesis as measured by the formation of monounsaturated fatty acids from stearate was significantly higher than that from palmitate. The rate of [1-(14)C]stearate incorporation into oleate [1208 +/- 195 pmol/(mg protein x 4 h)] was 80% higher than that of [1-(14)C]palmitate [(672 +/- 82 pmol/(mg protein x 4 h)]. Despite the different rates of desaturation, the cellular oleate concentrations did not differ in the cells treated with stearate and palmitate (i.e., 42.5 +/- 4.5 vs. 40.8 +/- 5.2 nmol/mg protein). On the other hand, oleate concentration in the cells incubated with exogenous oleate was 198.1 +/- 9.5 nmol/mg protein. There was a dose-dependent increase in cellular stearate concentration by increasing stearate concentrations from 0.5 mmol/L to 4.0 mmol/L in culture medium. A linear increase in cellular stearate concentration was also achieved by increasing the duration of incubation with 1.0 mmol/L stearate from 2 to 24 h. Despite the marked increases in stearate concentrations under these conditions, oleate concentrations remained unchanged in the cells. These results do not support the contention that the hypocholesterolemic effect of stearate may be mediated by its conversion to oleate, although stearate is a more favorable substrate for desaturation than palmitate.

Animals↗

PubMed1996

Stearic acid unlike shorter-chain saturated fatty acids is poorly utilized for triacylglycerol synthesis and beta-oxidation in cultured rat hepatocytes.

Utilization of stearate as compared to various saturated fatty acids for cholesterol and lipid synthesis and beta-oxidation was determined in primary culture of rat hepatocytes. At 0.5 mmol/L in the medium, stearate (18:0) adequately solubilized by albumin was less inhibitory to cholesterol synthesis from [2-14C] acetate than myristate (14:0) and palmitate (16:0) (68% vs. 91 and 88% inhibition, respectively). The rate of incorporation into cholesterol from [1-14C] stearate (3.0 +/- 0.6 nmol/mg protein/4 h) was 37-, 1.8-, and 7.8-fold of that from myristate, palmitate, and oleate, respectively. Conversely, the rate of [1-14C] stearate incorporation into total glycerolipids was 88-90% lower than that of labeled palmitate, myristate, and oleate. The rate of [1-14C] stearate incorporation into triacylglycerol (3.6 +/- 0.4 nmol/mg protein/4 h) was 6-8% of that from myristate, palmitate, oleate, and linoleate. The rate of stearate incorporation into phospholipids was the lowest among tested fatty acids, whereas the rate of mono- and diacylglycerol synthesis was the highest with stearate treatment. The rate of beta-oxidation as measured by CO2 and acid soluble metabolite production was also the lowest with [1-14C] stearate treatment at 22.7 nmol/mg protein/4 h, which was 35-40% of those from other [1-14C] labeled fatty acids. A greater proportion of stearate than other fatty acids taken up by the hepatocytes remained free and was not metabolized. Clearly, stearate as compared to shorter-chain saturated fatty acids was less efficiently oxidized and esterified to triacylglycerol in cultured rat hepatocytes.

Animals↗

PubMed1996

Triacylglycerol and cholesterol transport during absorption of glycerol trioleate vs. glycerol trielaidate.

We used conscious, chronic lymph-fistula rats to compare intestinal lymphatic transport of glycerol trioleate (TO) vs. glycerol trielaidate (TE) and to determine the effect of TO vs. TE on absorption and transport of cholesterol. Rats were implanted with intestinal lymph fistulas and duodenal cannulas and then given intraduodenal infusions of lipid emulsions containing purified TO or TE (40 mumol/h) and cholesterol (7.8 mumol/h + 2 microCi [14C]cholesterol). Lymph samples were collected at 0, 2, 4, 5, 6, 7, and 8 h after the start of lipid infusion. Lymphatic output and luminal and gut wall recovery of radioactive lipid at 8 h were quantified. Triacylglycerol (TG) fatty acid isomers did not affect lymphatic output of TG; lymph TG fatty acid composition and output reflected infusate composition. Lymphatic output of cholesterol (mass and radioactivity) did not differ between groups; luminal and gut wall recovery of [14C]cholesterol was also similar between groups. Similar lymphatic transport of TG and cholesterol between triolein- and trielaidin-infused rats was maintained for up to 16 h after the cessation of an infused lipid load. These results indicate that TO and TE are transported into lymph similarly, and that cholesterol absorption and transport are similar irrespective of whether TO or TE is the TG source. The data suggest that trans fatty acid-induced hypercholesterolemia is not due to altered intestinal absorption and transport of cholesterol.

Animals↗

PubMed1995

Segregation by color and stereoscopic depth in three-dimensional visual space.

Two experiments were conducted to investigate how color and stereoscopic depth information are used to segregate objects for visual search in three-dimensional (3-D) visual space. Eight observers were asked to indicate the alphanumeric category (letter or digit) of the target which had its unique color and unique depth plane. In Experiment 1, distractors sharing a common depth plane or a common color appeared in spatial contiguity in the xy plane. The results suggest that visual search for the target involves examination of kernels formed by homogeneous items sharing the same color and depth. In Experiment 2, the xy contiguity of distractors sharing a common color or a common depth plane was varied. The results showed that when target-distractor distinction becomes more difficult on one dimension, the other dimension becomes more important in performing visual search, as indicated by a larger effect on search time. This suggests that observers can make optimal use of the information available. Finally, color had a larger effect on search time than did stereoscopic depth. Overall, the results support models of visual processing which maintain that perceptual segregation and selective attention are determined by similarity among objects in 3-D visual space on both spatial and nonspatial stimulus dimensions.

Color Perception↗

PubMed1994

Arachidonic acid and eicosapentaenoic acid stimulate type II pneumocyte surfactant secretion.

Arachidonic acid and its leukotriene metabolites have been shown to stimulate surfactant secretion by alveolar type II cells. The present study was undertaken to determine the effects of various unsaturated fatty acids, including eicosapentaenoic acid, on surfactant secretion. Surfactant secretion was expressed as the percent of [3H]choline-derived phospholipids released into culture medium by type II pneumocytes of adult rats. Consistent with the earlier findings, arachidonic acid stimulated secretion in a concentration-dependent fashion (3.5-21 microM), doubling baseline secretion at 21 microM. Eicosapentaenoic acid was found to be equally effective as arachidonic acid in stimulating secretion. A comparison with palmitic, oleic and linoleic acids revealed that highly unsaturated fatty acids stimulated secretion to the greatest extent. This was supported by a positive correlation between degree of unsaturation (i.e., 0, 1, 2, 4 and 5 double bonds) and stimulation of surfactant secretion. In the present study, exogenous leukotriene E4 (10(-13)-10(-6) did not stimulate surfactant secretion. Neither nordihydroguairetic acid (0.1 microM) nor indomethacin (0.1 microM) affected arachidonic acid-stimulated secretion. The stimulatory effects of arachidonic acid and eicosapentaenoic acid on surfactant secretion were related to the highly unsaturated nature of the fatty acids and were not mediated by increased levels of cyclic adenosine monophosphate or calcium.

Animals↗

PubMed1994

Garlic reduces plasma lipids by inhibiting hepatic cholesterol and triacylglycerol synthesis.

Prompted by the reported hypolipidemic activity of garlic, the present study was undertaken to elucidate the mechanism(s) underlying the cholesterol-lowering effects of garlic. Rat hepatocytes in primary culture were used to determine the short-term effects of garlic preparations on [1-14C]acetate and [2-3H]glycerol incorporation into cholesterol, fatty acids and glycerol lipids. When compared with the control group, cells treated with a high concentration of garlic extracts [i.e., petroleum ether- (PEF), methanol- (MEF) and water-extractable (WEF) fractions from fresh garlic] showed decreased rates of [1-14C]acetate incorporation into cholesterol (by 37-64%) and into fatty acids (by 28-64%). Kyolic containing S-allyl cysteine and organosulfur compounds inhibited cholesterogenesis in a concentration dependent manner with a maximum inhibition of 87% at 0.4 mM. At this concentration, Kyolic decreased [1-14C]acetate incorporation into fatty acids by 67%. S-allyl cysteine at 2.0 and 4.0 mM inhibited cholesterogenesis by 20-25%. PEF, MEF and WEF depressed the rates of [2-3H]glycerol incorporation into triacylglycerol, diacylglycerol and phospholipids in the presence of acetate, but not in the presence of oleate. The results suggest that the hypocholesterolemic effect of garlic stems, in part, from decreased hepatic cholesterogenesis, whereas the triacylglycerol-lowering effect appears to be due to inhibition of fatty acid synthesis. Primary hepatocyte cultures as used in the present study have been proven useful as tools for screening the anticholesterogenic properties of garlic principles.

Acetates↗

PubMed1994

Selectivity of cyclopean masking for the spatial frequency of binocular disparity modulation.

Previous studies have presented evidence for the existence of channels tuned to the spatial frequency (SF) of binocular disparity modulation. Bandwidths reported for masking curves were extremely narrow, possibly because of off-frequency viewing, whereby observers can best detect a signal with a channel tuned to an SF on the opposite side of the signal from the masker's SF, rather than with a channel tuned directly to the signal's SF. Herein are reported the results of four detection experiments. Experiment 1 measures unmasked threshold for detection of a cyclopean grating. Experiments 2-4 are masking experiments. Experiment 2 demonstrates that threshold for detection of a cyclopean grating is proportional to the intensity of masking noise, which is consistent with the operation of linear channels. Experiments 3 and 4 demonstrate that masking curves are narrower when obtained with narrowband-noise maskers than when obtained with notched-noise maskers, which render the off-frequency viewing ineffective. Implications for understanding the processing of cyclopean images are discussed.

Adult↗