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Biomedical subjects

S Y Oh

Publications and source records attributed to S Y Oh.

At least 73 records · Page 4Linked to original sources
PubMed1991

Studies of women eating diets with different fatty acid composition. I. Plasma lipoproteins and steroid excretion.

Moderate changes in dietary fat composition have been recommended to improve plasma cholesterol status. Such changes have not been studied extensively in women. This research evaluates plasma lipoprotein and steroid excretion changes in young women who consumed a diet similar to US average consumption in 1974 [40 en% fat, polyunsaturated (P) to saturated fatty acid (S) ratio, P/S = 0.3, US74] or a diet modified to contain 30 en% fat, P/S = 1.0 (MOD). Following a preexperimental period of self-selected diets, young women were fed the diets for 28-day periods in a crossover design with 10 women at the University of Nebraska, Lincoln, and 10 at Iowa State University, Ames. Plasma lipoproteins and steroid excretion were quantitated and the compositions determined. Data were analyzed for race (five Chinese, 14 Caucasians) and for diet carryover effects, as well as for primary diet effects. In the Chinese women, the US74 diet raised total and very-low-density lipoprotein (VLDL) cholesterol compared to prior self-selected or modified diets; in the Caucasian women the MOD diet lowered total, low-density lipoprotein (LDL), and VLDL cholesterol. The diet carryover was evident in total high-density lipoprotein (HDL) and HDL3 cholesterol. Total HDL and HDL3 cholesterol in response to the US74 diet were unchanged from the MOD diet when the US74 diet followed the MOD diet, but were lower than modified when the US74 diet followed self-selected diets. The US74 diet resulted in greater neutral sterol excretion than the MOD diet; this response was more marked in the self-selected, US74, MOD sequence than in the self-selected, MOD, US74 sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Eggs enriched in omega-3 fatty acids and alterations in lipid concentrations in plasma and lipoproteins and in blood pressure.

Effects of dietary eggs enriched with omega-3 fatty acids on lipid concentrations in plasma and lipoproteins and blood pressure were determined in 11 men and women in two groups. Group 1 consumed four omega-3 eggs per day during the first 4-wk period and four control eggs for the second 4-wk period. Group 2 ate the same number of eggs in the reverse order. Mean plasma cholesterol concentration was significantly increased by control eggs (P less than 0.01) but unchanged by omega-3 eggs. Mean plasma triglyceride concentration was decreased by omega-3 eggs but increased by control eggs. Both systolic and diastolic blood pressures were significantly lowered by omega-3 eggs in group 1 whereas only systolic pressure was significantly decreased on omega-3 eggs in group 2. The control eggs did not change blood pressure. In conclusion, the omega-3 eggs may be more healthful than the control eggs.

Adult↗
PubMed1990

Low probability of double integration in transformation of nonpermissive cells by polyomavirus.

The fate of polyomavirus genomes in stable transformants was examined in experiments in which rat or hamster cells were infected with mixed viral populations containing either two distinguishable wild types or a wild type plus a transformation-deficient mutant. The results demonstrate that in 90% of the cases in either situation, a single polyomavirus parental genome became integrated into the host genome. Both parents in the mixed infection were present in the same cells and both persisted in the infected cells until transformants appeared, eliminating the possibility that one virus would exclude the other in the early steps of the infection process. We believe that these results can be generalized to transformation events derived from normal single infections. Thus, contrary to previous results for the number of integration sites determined by restriction endonuclease and blot hybridization analysis, it appears that the probability for more than one integration event in transformation by polyomavirus is low (1 in 10). A reinterpretation of previous data is proposed.

Animals↗
PubMed1989

Altered regulation of intercellular communication by epidermal growth factor, transforming growth factor-beta and peptide hormones in normal human keratinocytes.

Since many chemical tumor promoters and some oncogenes have been shown to inhibit gap junction-mediated intercellular communication, the effect of various growth factors on gap junctional intercellular communication on normal human keratinocytes was examined. In order to measure the effect of the growth factors on gap junctional communication, the scrape loading/dye transfer technique was used on human keratinocytes grown in a serum-free medium in vitro. At 24 h after treatment epidermal growth factor (10 ng/ml), transforming growth factor-beta (1 ng/ml), whole bovine pituitary extract (70 micrograms/ml) and 12-O-tetradecanoylphorbol-13-acetate (TPA) (100 ng/ml) inhibited intercellular communication. Treatment of these cells with transforming growth factor-beta (1 ng/ml) induced morphological changes in some of the cells and brought about selective intercellular communication within and between the nonaltered and altered cells. Epidermal growth factor and whole bovine pituitary extract, significantly enhanced [3H]thymidine uptake and also stimulated cellular proliferation under the experimental conditions used to inhibit intercellular communication. Both transforming growth factor-beta and TPA markedly inhibited [3H]thymidine uptake and induced differentiation of some of these cells. In order to study the possible mechanism by which the growth factors might inhibit intercellular communication, the effect of the growth factors on protein kinase C activation and alterations of intracellular free calcium was investigated. The results indicated that neither protein kinase C nor an increase in [Ca2+]i were involved in the modulation of gap junctional communication by epidermal growth factor or transforming growth factor-beta. The study suggests that in the human keratinocytes inhibition of intercellular communication may be involved (i) in the action of growth factors such as epidermal growth factor during cellular proliferation and (ii) in the differentiation of primary keratinocytes by transforming growth factor-beta.

Calcium↗
PubMed1988

Effects of low fat diets differing in degree of fat unsaturation on plasma lipids, lipoproteins, and apolipoproteins in adult men.

The effects of two low fat diets with differing ratios of polyunsaturated to saturated fatty acids (P/S) on blood lipids, lipoproteins (LP), and apolipoproteins (Apo) were studied in 23 adult men, 30-60 years old, using a crossover design. Both test diets had 25% fat calories with either a P/S of 0.3 (Diet 1) or a P/S of 1.0 (Diet 2) and equivalent amounts of cholesterol. The study consisted of four periods: a 5-week prestudy on self-selected diet (SS), two 6-week test diet periods followed by a second 5-week post-study period on the SS diet. When compared with the SS diet, Diet 2 lowered the mean plasma total cholesterol (TC) by about 20% (P less than 0.01). Low density lipoprotein (LDL) cholesterol was also decreased by about 18% by Diet 2 (P less than 0.01). The high P/S diet did not cause a change in total cholesterol in the high density lipoprotein (HDL) subclass2 (HDL2) when compared to the SS diet. Levels of triglycerides (TG) were slightly reduced in HDL2 but showed a greater reduction in HDL3 in both diets. Phospholipids (PL) were significantly reduced in HDL2 and in HDL3, but the reduction in HDL3 PL was not statistically significant. Apo A-I levels were not changed by either diet when compared with the SS diet, but Apo A-II levels of HDL2 and HDL3 were significantly decreased by the low fat diets, and there was no P/S effect. No other consistent changes in apoprotein levels occurred. Our data suggest that, in men with normal lipid levels, practical dietary changes involving a moderate increase in P/S from 0.3 to 1.0 in a low fat, low cholesterol diet do influence lipoprotein composition and apoprotein distribution in a short time. The reduction in cholesterol in total lipid composition and in LDL lipids which accompanied the reduction of dietary fat and cholesterol are considered to be beneficial.

Adult↗
PubMed1988

Inhibition of gap junctional blockage by palmitoyl carnitine and TMB-8 in a rat liver epithelial cell line.

Exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA) has been shown to inhibit gap junctional intercellular communication (GJIC) in many cell types in vitro. Using a scrape loading/dye transfer technique, TPA was shown to cause a dose-dependent and transient inhibition of GJIC in WB-F344, a normal rat liver epithelial cell line. Such a down-modulation of intercellular communication was found to be associated with an increase in protein kinase C (PKC) activity. Translocation of this activity to the particulate fraction occurred 10 min after exposure to 16 nM TPA and was consistent with the time course needed to inhibit GJIC. After 6 h exposure to TPA, essentially all the PKC activity was lost concurrent with the recovery of communication in these cells. During this time, the cells also became refractory to inhibition by further addition of TPA. Blockage of communication induced by TPA in WB cells was prevented by treating the cells with 23 microM palmitoyl carnitine for 1 h or 100 microM 8-N, N-(diethylamino)-octyl-3,4, 5-trimethoxybenzoate for 30 min. The results indicate that TPA transiently modulates GJIC in WB cells and PKC activation is possibly involved in blockage of communication in these cells.

Animals↗
PubMed1987

Detoxication of cyanide in the chicken by conversion to thiocyanate, as influenced by the availability of transferable sulphur.

The urinary excretion of thiocyanate by hens after dosage with cyanide (30 mumol) has been studied in a series of acute experiments involving 6 hr urine collection periods. More than half of the dose could be recovered as thiocyanate when cyanide was given by intravenous infusion and the rate of excretion closely paralleled plasma thiocyanate concentration. Little cyanide was excreted directly. The excretion of thiosulphate fell by an amount that suggested that availability of sulphane sulphur might limit the extent of conversion. However, neither thiosulphate nor sulphur amino acids enhanced thiocyanate excretion when they were infused together with cyanide; indeed, thiocyanate excretion decreased as the level of sulphur compound given was increased. Both nitrite and sulphite depressed thiocyanate excretion also but they differed in their effects on plasma thiocyanate levels and the pattern of urinary excretion. Comparison of excretion from both sides of the kidneys separately emphasised the importance of the first pass of cyanide in its conversion to thiocyanate. The results suggest that although sulphur availability may be limited the in vivo production of sulphite also restricts cyanide detoxication.

Animals↗
PubMed1985

Effect of dietary cholesterol and degree of fat unsaturation on plasma lipid levels, lipoprotein composition, and fecal steroid excretion in normal young adult men.

Effect of four test diets differing in the ratio of polyunsaturated to saturated fats (P/S, 1.8 vs 0.28) and two cholesterol levels (1,000 vs 300 mg/day) for each level of the P/S ratio was determined on plasma lipid levels, lipoprotein compositions and concentrations, and fecal steroid excretion in a controlled diet study with 11 normal young men using a crossover design. Plasma cholesterol levels were significantly decreased by the diets high in P/S ratio regardless of the dietary cholesterol levels (14% decrease by high cholesterol and 20% in low cholesterol) while the diets low in P/S ratio increased cholesterol by an average of 24 and 22% in presence of high and low cholesterol, respectively. Lipids and apoproteins of lower-density lipoproteins were changed in accordance with those of plasma cholesterol but changes in high-density lipoprotein (HDL) appear to depend on both cholesterol content and P/S ratio. Dietary cholesterol level profoundly influenced the excretion of neutral sterols and diets high in P/S ratio significantly (p less than 0.05) increased fecal bile acid extraction. The present study demonstrated that dietary polyunsaturated fats, when a moderate amount was consumed, were effective and beneficial hypocholesterolemic nutrients without reducing HDL-cholesterol.

Adult↗
PubMed1985

Effect of dietary egg on variability of plasma cholesterol levels and lipoprotein cholesterol.

The effects of dietary cholesterol on plasma cholesterol levels, its distribution among lipoproteins, and apoproteins of high-density lipoprotein subclasses in individuals who did and did not demonstrate response in plasma cholesterol levels were studied in 21 healthy middle-aged men for 3 mo. After consumption of 3 eggs/day in addition to their habitual diets for 28 days, 21 subjects were divided into 8 hyper- and 13 hypo-responders. The average plasma cholesterol level of the 21 subjects was changed from 188 +/- 36 to 199 +/- 36 mg/100 ml over the 28-day classification period. During the same period the mean plasma cholesterol level of the hyper-responders was significantly increased (p less than 0.025) from 170 +/- 41 to 199 +/- 29 mg/100 ml while that of the hypo-responders fell slightly. The addition of six eggs to the daily diet of the hypo-responders did not alter the mean plasma cholesterol level but resulted in a wide difference in response of plasma cholesterol concentration. The 13 hypo-responders were divided into hypo-hyper-responders (n = 6) and hypo-hypo-responders (n = 7) depending upon the degree of change in plasma cholesterol level. The present study illustrated the variabilities of plasma cholesterol level among free-living subjects who demonstrated two-stage thresholds of response to dietary intake of cholesterol.

Adult↗
PubMed1984

Recombination induces tandem repeats of integrated viral sequences in polyoma-transformed cells.

Transformed Fischer rat cells derived from coinfections with wild-type polyoma virus and transformation-deficient hr-t deletion mutants were studied. The structure of the integrated viral DNA was determined by Southern blot analysis of high-molecular-weight DNA. In several cases the two parental genomes were found cointegrated in a head-to-tail manner at a single site in the host DNA. The results indicate that parental viral genomes recombine in Fischer rat cells in the process of transformation, and that the commonly observed tandem integration of viral genomes in polyoma-transformed cells must be due, in part, to recombination events.

Animals↗
PubMed1982

[Experience with measurements of intracranial pressure in post-hypoxic and post-traumatic coma].

In 27 patients intracranial pressure monitoring (ICP) was carried out for 4-5 days (severe head injury 23, hypoxia after cardiac arrest 3, brain tumor 1). Patients were included who reached a score of 8 or less on the Glasgow Coma Scale and who did not need immediate surgery. The measurements were done with epidural screws (20 patients) and with indwelling ventricular catheters 7). The individually highest ICPs were recorded 3-4 days after incident. 14 patients recovered completely, 3 remained slightly and 3 severely disabled, and 7 patients died. ICP monitoring permitted precise and rational therapeutic management but was of little value prognostically. Poor Glasgow scores were linked to high mortality. The advantages and disadvantages of the two ICP monitoring techniques are discussed. ICP monitoring is recommended as a useful and safe tool for titrated management of deeply comatose patients.

Adult↗
PubMed1982

[Diagnosis of brain death and organ donation].

The Swiss Academy of Medical Sciences published its guidelines for brain death evaluation and removal of donor organs in 1968. Based on this, the authors have designed a formal written protocol for brain death certification with the object of establishing the diagnosis of brain death beyond doubt and within reasonable time. The protocol serves for identification of suitable organ donors.

Brain Death↗
PubMed1981

Aortic transmural serum protein transport: effect of concentration, time, and location.

The diffusive transport of certain 125I-labeled purified serum proteins, canine (C), human (H), and porcine (P) serum albumin (A), as well as human high-density lipoprotein (HDL), into the isolated deendothelialized intimal-medial thoracic aortic preparation was measured as a function of protein concentration (c0), intimal surface exposure time (T), and location (z) along the vessel at 21 degrees C. Selected proteins were studied in each of 11 canine preparations and 1 porcine preparation. The resulting uptake (M, nmol/cm2) was measured by direct gamma counting of specially excised fixed tissue specimens, and the transmural concentration distributions [c(xi), nmol/cm3] were calculated from electron probe X-ray microanalysis of the silver distributions across specially prepared microautoradiographs. The results showed 1) that the processes associated with the diffusive transport of CA, HA, PA, and HDL into the intimal-medial system are independent of c0, i.e., uptake is proportional to c0, 2) that the uptake of CA for short times appeared to be linear with T 1/2, 3) that the apparent wall-plasma partition coefficient for albumin rangers between 0.1 and 0.2, 4) that the apparent tissue albumin diffusion coefficient is approximately 2.7 X 10(-8) cm2/s, 5) that the transport processes for HA and CA are indistinguishable, 6) that the processes for the transport of HDL are two times slower than those for HA or CA, and 7) that the transport rate for albumin tends to decrease with z.

Animals↗
PubMed1981

Effect of arterial stretch on transmural albumin and Evan's blue dye transport.

The influence of arterial wall circumferential stretch (lambda) on the 32-min diffusive mural uptake of 125I-albumin and of Evan's blue dye (EBD) across the injured endothelial surface was studied in the intimal-medial preparation of the canine descending thoracic aorta (DTA). Albumin uptake (MA nmol/cm2) was measured by standard gamma counting techniques and the corresponding EBD uptake (ME) by the reflectance method. MA and ME were measured at a physiological stretch (lambda = 1.4) and at a hypertensive stretch (lambda = 1.8) at four equispaced locations (z) along the DTA. When lambda was changed from 1.4 to 1.8, the average percentage change of MA was -2% and of ME was -4%. These decreases were not significant (P greater than 0.10), and we conclude that arterial wall stretch exerts only minor influence on the parameters governing albumin and EBD-albumin accumulation in the intimal surface of the deendothelialized arterial intimal-medial tissue system.

Absorption↗
PubMed1980

Quantitative microautoradiography of arteries: comparison of radioactivity to silver.

The local concentration of silver in developed aortic transmural microautoradiographs was compared to the corresponding 125I-labeled albumin radioactivity concentration [ci(x)] in the subjacent tissue. Silver [s(x)] was measured by electron probe X-ray microanalysis (EPA) and the corresponding ci(x) by direct gamma-ray counting. The results show 1) that the relationship between volume-averaged values of radioactivity (ci) and EPA signal (s) is adequately described by ci = Ks, where K is a proportionality constant, and 2) that ci(x) measured by EPA [i.e., Ks(x)] agrees closely with ci(s) measured direcly from en face microtomy slices of corresponding unfixed tissue specimens.

Animals↗
PubMed1979

Altered metabolism (in vivo and in vitro) of plasma lipoproteins after selective chemical modification of lysine residues of the apoproteins.

Chemical modification of lysine residues by acetoacetylation of the apoproteins of iodinated canine and human low density lipoproteins (LDL) and canine high density lipoproteins (HDL) resulted in a marked acceleration in the rate of removal of these lipoproteins from the plasma after intravenous injection into dogs. Clearance of the lipoproteins from the plasma correlated with their rapid appearance in the liver. Acetoacetylated canine (125)I-LDL (30-60% of the lysine residues modified) were essentially completely removed from the plasma within an hour, and > 75% of the activity cleared within 5 min. Reversal of the acetoacetylation of the lysine residues of the LDL restored to these lipoproteins a rate of clearance essentially identical to that of control LDL. Identical results were obtained with modified human LDL injected into dogs. At 10 min, when congruent with 90% of the acetoacetylated human (125)I-LDL had been removed from the plasma, 90% of the total injected activity could be accounted for in the liver. Furthermore, it was possible to demonstrate an enhancement in uptake and degradation of acetoacetylated LDL by canine peritoneal macrophages in vitro. The mechanism(s) responsible for the enhanced removal of the LDL and HDL in vivo and in vitro remains to be determined. By contrast, however, acetoacetylation of canine (125)I-apoE HDL(c) did not accelerate their rate of removal from the plasma but, in fact, retarded their clearance. Control (native) apoE HDL(c) were removed from the plasma (64% within 20 min) and rapidly appeared in the liver (39% at 20 min). At the same time point, only 45% of the acetoacetylated apoE HDL(c) were cleared from the plasma and <10% appeared in the liver. Acetoacetylation of the apoE HDL(c) did not enhance their uptake or degradation by macrophages. The rapid clearance from the plasma of the native apoE HDL(c) in normal and hypercholesterolemic dogs suggests that the liver may be a normal site for the removal of the cholesteryl ester-rich apoE HDL(c). The retardation in removal after acetoacetylation of apoE HDL(c) indicates that the uptake process may be mediated by a lysine-dependent recognition system.

Acetoacetates↗