Angiotensin I-converting enzyme gene polymorphism and acute response to captopril in essential hypertension

Insertion/deletion (I/D) polymorphism of the angiotensin converting enzyme (ACE) gene has been shown to be a determinant for serum ACE level and a marker for several cardiovascular diseases. We investigated whether the ACE gene can predict the therapeutic efficacy of ACE inhibitors in essential hypertensive patients. The response of blood pressure and plasma renin activity (PRA) 1 h after 50 mg captopril administration were evaluated in 82 inpatients with untreated essential hypertension (42 men, 40 women; mean age +/- SD: 52 +/- 13 years; range: 27 to 79 years) in relation to ACE genotypes. There were no differences in age, gender, blood pressure, and PRA in the basal conditions, among essential hypertensive patients with the II, ID, and DD genotypes (n = 36, 34, and 12, respectively). The acute responses of PRA and blood pressure to an ACE inhibitor were similar in the three groups. The blood pressure response was negatively correlated with baseline PRA (r = 0.497). These data suggest that PRA but not the I/D polymorphism of the ACE gene is a useful predictor of the short-term antihypertensive effects of ACE inhibitors.

Change in blood pressure during altered sodium intake is not associated with calciotropic hormone level

1. We evaluated the effects of the dietary restriction of sodium chloride on blood pressure and systemic calcium metabolism in 19 in-patients with essential hypertension (11 men and 8 women, mean age 49.9 +/- 12.1 years). 2. All patients received a high-sodium diet (250 mmol/day) for 1 week, followed by a low-sodium diet (10 mmol/day) for another week. Intake of potassium (100 mmol/day) and of calcium (15 mmol/day) were kept constant throughout the study. 3. Sodium restriction significantly reduced the mean blood pressure (from 114.0 +/- 1.9 to 105.0 +/- 13.7 mmHg, P < 0.01). Urinary calcium excretion was significantly reduced (from 5.1 +/- 2.4 to 2.2 +/- 1.0 mmol/day, P < 0.01). 4. The change in mean blood pressure after sodium restriction was not correlated with a change in any parameter of calcium metabolism [whole blood ionized calcium, plasma intact parathyroid hormone, or 1,25-(OH)2 vitamin D3]. 5. Plasma renin activity during a regular sodium diet, an index of renin status, was significantly and inversely correlated with the change in blood pressure during sodium restriction, but not with any change in the parameters of calcium metabolism. 6. We conclude that sodium restriction reduces blood pressure and decreases urinary calcium excretion. However, we observed no significant role of extracellular calcium concentration or of calciotropic hormone concentration in the mechanism of sodium sensitivity.

Nocturnal decline in blood pressure is attenuated by NaCl loading in salt-sensitive patients with essential hypertension: noninvasive 24-hour ambulatory blood pressure monitoring

We investigated the effect of NaCl on the circadian blood pressure rhythm in patients with essential hypertension classified according to the presence or absence of salt sensitivity. We obtained 24-hour noninvasive ambulatory blood pressure measurements in 64 Japanese patients with mild to moderate essential hypertension who ate a low NaCl diet (50 mmol/d) for 1 week, followed by a high NaCl diet (340 mmol/d) for 1 week. Twenty-six patients whose mean blood pressure was increased more than 10% by NaCl loading were classified as salt sensitive. The remaining 38 patients were classified as salt resistant. The nocturnal decline in mean blood pressure was significantly smaller in salt-sensitive patients (8.3+/-1.0%) than in salt-resistant patients (11.5+/-0.9%) (P<.05) during a high NaCl diet but was similar in both groups during a low NaCl diet. There was no significant difference in the prevalence of the non-dipper pattern between groups on a low NaCl diet, but the prevalence of the non-dipper pattern was significantly higher in salt-sensitive patients than in salt-resistant patients on a high NaCl diet (0.57 versus 0.26, chi2=6.4; P=.02; odds ratio, 3.82). These findings suggest that the NaCl loading blunted the nocturnal decline in blood pressure in salt-sensitive patients but not in salt-resistant patients.

Extracellular Mg2+ inhibits capacitative Ca2+ entry in vascular smooth muscle cells

BACKGROUND

Agonist-induced Ca2+ entry is thought to be mediated by capacitative Ca2+ entry other than L-type Ca2+ channels in vascular smooth muscle cells (VSMCs). The mechanism for capacitative Ca2+ entry has not been fully elucidated. Our objective was to examine the effect of external Mg2+ on capacitative Ca2+ entry in cultured rat aortic VSMCs.

METHODS AND RESULTS

Three doses of external Mg2+ concentration (nominally 0, 1, and 5 mmol/L) were used. After exposure to 1 mumol/L, angiotensin II (Ang II) in Ca(2+)-free medium, addition of Ca2+ to the medium caused an increase in cytosolic free Ca2+ concentration ([Ca2+]i), indicating Ang II-induced Ca2+ influx. This Ca2+ influx was attenuated in cells preincubated with high external Mg2+ concentrations or with 1 mumol/L nifedipine. After VSMCs in Ca(2+)-free medium were exposed to 1 mumol/L thapsigargin, which inhibits the sarcoplasmic reticulum Ca(2+)-ATPase and depletes Ca2+ stores, addition of Ca2+ to the medium induced an increase in [Ca2+]i, indicating capacitative Ca2+ entry. This entry pathway was found to be independent of dihydropyridine-sensitive Ca2+ channels and inhibited by increased external Mg2+ concentration. External Mg2+ concentration did not influence Ca2+ efflux across the plasma membrane after stimulation with Ang II plus thapsigargin.

CONCLUSIONS

Results suggest that in VSMCs, capacitative Ca2+ entry is reduced by external Mg2+. This mechanism may explain in part the inhibitory effect of external Mg2+ on Ca2+ handling.

Pentaerythritol tetranicotinate (niceritrol) decreases plasma lipoprotein(a) levels

We determined the most effective dosage of pentaerythritol tetranicotinate (niceritrol) to reduce plasma lipoprotein(a) [Lp(a)] levels in 44 Japanese patients (16 men and 28 women; mean age, 59.2 +/- 10.8 years) with hyperlipidemia types IIa, IIb, and IV. Patients received oral niceritrol at a dosage of 750 mg (3 tablets)/d for 8 weeks, followed by 1,500 mg (6 tablets)/d for 8 weeks. Administration of niceritrol 750 mg/d for 8 weeks decreased total and low-density lipoprotein (LDL) cholesterol in patients with type IIa hyperlipidemia and decreased triglycerides in patients with type IV hyperlipidemia, but did not affect Lp(a). However, niceritrol 1,500 mg/d for 8 weeks decreased Lp(a) in patients with initial Lp(a) levels greater than 30 mg/dL in addition to decreasing total and LDL cholesterol and triglycerides. These results suggest that the effective dosage of niceritrol to reduce the serum Lp(a) concentration in Japanese hyperlipidemic patients with a high Lp(a) level (> or = 30 mg/dL) is greater than 1,500 mg/d.

Whole-blood incubation method to study neutrophil cytoskeletal dynamics

To reduce artifactual effects in the study of filamentous (F)-actin dynamics in neutrophils, we have developed a whole-blood incubation method. Neutrophils in whole blood contained significantly less basal F-actin than did separated neutrophils. Although the peak relative F-actin content of neutrophils in whole blood after formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation was significantly higher than that of separated neutrophils at 10(-9) to 10(-6) M fMLP concentrations (p < 0.05), there was no significant difference in increase in mean fluorescence intensity and the EC50 (concentration of stimulant giving a half-maximum response). On the other hand, the EC50 of platelet-activating factor (PAF) between separated neutrophils and whole-blood-incubated neutrophils differed significantly (1.6 +/- 1.1 x 10(-9) M in separated neutrophils and 2.0 +/- 0.7 x 10(-8) M in whole-blood-incubated neutrophils, p < 0.05). The whole-blood incubation method described presently reduces the sample volume, cost and time needed to separate neutrophils, prevents neutrophil activation during separation, and reserves all blood components that may affect neutrophil function. For these reasons, the conditions adopted in the present method are thought to simulate well neutrophils circulating in vivo and the method would be preferable to other neutrophil function tests performed to study actin dynamics.

Enhancement of chemotherapeutic effects with focused shock waves: extracorporeal shock wave chemotherapy (ESWC)

The effects of shock waves in combination with various anti-cancer agents i.e. Bleomycin(BLM), Cis-platinum (CDDP) and 5-fluorouracil(5-FU) on various human cancer cells were examined. It was only with BLM that enhancement was evident in all cell lines. The degree of chemotherapeutic enhancement was proportional to the amount of shock wave energy applied. Ladder formation of DNA in GCIY, a gastric cell line, was observed only when treated with both BLM and shock waves in combination. When SW 480, a colon cancer cell line, transplanted into the back of nude mice were treated with a combination of i.v. injected BLM and regional exposure to shock waves, a significant enhancement of chemotherapeutic effects was observed in terms of the tumor growth curve. When cancer cells exposed to shock waves and observed under scanning and transmission electron microscopes, microvilli on the cell surface disappeared and numerous dimples(diameters distributed from 0.05 to 0.5 microns) became apparent. These dimples were concluded to be pores penetrating through the cell membrane, because reagents such as propidium iodide or 5(6)-carboxyfluorescein could enter cells treated shock waves.

[Evaluation of angiotensin I converting enzyme gene polymorphism in patients with essential hypertension and coronary artery disease]

We investigated the role of the insertion (I)/deletion(D) polymorphism in the angiotensin I converting enzyme (ACE) gene in the cardiovascular diseases. First, we studied 520 patients who had undergone coronary angiography: including 220 patients with acute myocardial infarction, 98 patients with effort angina pectoris (> 75% stenosis), 83 patients with vasospastic angina and 119 controls with normal coronary artery. There was no difference in the frequency of ACE gene I/D allele or genotype II, ID and DD among the four groups. Second, we studied the correlation between ACE gene I/D polymorphism and the clinical characteristics in patients with essential hypertension. The distribution of I/D allele and genotype were similar in 140 essential hypertensives and 83 normal controls. In patients with DD genotype, age at onset of hypertension was lower and left ventricular mass index was greater than those in patients with ID and II, although blood pressure levels and the severity of damage to other organs-were similar in the three groups. Further, 66 patients with essential hypertension were classified into 35 salt-sensitive and 31 salt-resistant patients according to changes in mean blood pressure during a week of low salt diet followed by a week of high salt diet. The frequency of I allele was significantly higher in the salt-sensitive group than in the salt-resistant group. In conclusion, ACE gene I/D polymorphism is not associated with coronary artery diseases. In patients with essential hypertension, the D allele was associated with early onset and left ventricular hypertrophy, while I allele was associated with salt sensitivity.

Induction of p53-independent apoptosis associated with G2M arrest following DNA damage in human colon cancer cell lines

The tumor suppressor p53 protein induces apoptosis in response to various kinds of DNA damage in normal cells, but it is still unclear whether or not apoptosis induced by DNA damage correlates with the p53 status in tumor cells. We determined the status of p53 by functional analysis of separated alleles in yeast in five human colon cancer cell lines, SW-480, SW-620, DLD-1, COLO320 and LS174T and investigated whether p53 is necessary for apoptosis and cell cycle arrest after treatment of the cells with a DNA-damaging agent, etoposide (VP-16), or gamma-irradiation. Of these cell lines, only LS174T expresses a functional p53. Apoptosis was detected in SW-480 and COLO320 cell lines, but not in the other cell lines, including LS174T cell line with a normal p53 function. Furthermore, cell cycle analysis revealed accumulation in the G2M phase preceding induction of apoptosis in SW-480 and COLO320 cells, but not in the other cells. These results suggest that apoptotic induction by DNA damage is not necessarily related to p53 status and that induction of p53-independent apoptosis following DNA damage may correlate with G2M arrest in the cell cycle, at least in the colon cancer cell lines used in this study.

Enhancing the effect of anticancer drugs against the colorectal cancer cell line with electroporation

Electroporation was applied in vitro and in vivo in the treatment of human colorectal cancer cell lines to study whether it can enhance the effect of bleomycin (BLM), 5-fluorouracil (5-FU) and cis-platinum (CDDP). We used LS174T and Colo320 cells derived from human colon cancer as target cells in this study. When the LS174T cells were used as target cells, the IC50 of BLM decreased to 10(-3) times, while that of 5-FU decreased to only about one fifth with the application of electric current. In the case of the Colo320 cells, the IC50 of BLM and 5-FU were about one hundredth and a half, respectively. The effect of CDDP was not enhanced with electric current. In vivo experiments were also performed using LS174T cells transplanted subcutaneously (s.c.) into nude mice. By treatment with intravenously (i.v.) administered BLM and simultaneous application of the electric current, tumors were markedly decreased in size after three weeks.

Modulation of target tissue response to angiotensin II and sodium sensitivity in Japanese patients with essential hypertension

"Non-modulators" are essential hypertensive patients who fail to modulate an adrenal response, renovascular response, or both, to angiotensin II (Ang II). The aim of the present study was to characterize "non-modulators" among Japanese patients with normal-renin essential hypertension and to determine whether non-modulation is related to sodium sensitivity of blood pressure. The increase in plasma aldosterone concentration (PAC response) and the decrease in renal plasma flow (RPF response) in response to Ang II infusion (3 ng/kg/min) were assessed in 15 Japanese patients with essential hypertension who received a high sodium diet (250 mEq/d) followed by a low sodium diet (10 mEq/d). The subjects were divided into two groups (6 modulators and 9 non-modulators) based on their ability to modulate the PAC response during sodium restriction. There was no significant difference between modulators and non-modulators in electrolyte balance or in plasma Ang II levels on either diet. Changes in the PAC response during sodium restriction were significantly correlated with the change in mean blood pressure during sodium restriction (r = -0.67, p < 0.01), while changes in the RPF response were not. RPF responses in both groups decreased during sodium restriction, although an effect on the RPF response in non-modulators was unexpected. These results suggest that non-modulators do exist among Japanese patients, but that this defect does not involve both the adrenal gland and the kidney. Apparently, only non-modulation of the adrenal response is involved in the mechanism of sodium sensitivity.

Effects of insulin on calcium metabolism and platelet aggregation

The influence of insulin on platelets in vitro has not been exhaustively investigated. To clarify whether insulin affects Ca2+ metabolism in platelets directly or through alteration of other systems regulating intracellular Ca2+ homeostasis, we examined the effect of insulin both alone and in combination with prostaglandin E1 on platelet aggregation and Ca2+ metabolism. Incubation of rat platelets with insulin reduced thrombin-induced Ca2+ influx but did not change thrombin-evoked release of Ca2+ from internal stores or the size of internal Ca2+ stores. The interactive effects of insulin with prostaglandin E1 were only additive, and insulin did not augment the effects of prostaglandin E1 on platelet Ca2+ metabolism. In contrast, insulin did not inhibit thrombin-induced platelet aggregation but did augment inhibition of platelet aggregation by prostaglandin E1. Our results suggest that insulin inhibits platelet function by both prostaglandin E1-dependent and -independent mechanisms.

Potentiation of the intracellular Ca2+ response to arginine vasopressin by increased cytosolic-free Mg2+ in rat vascular smooth muscle cells

Although the inhibitory effects of extracellular Mg2+ on Ca2+ influx are well established, little is known about the effects of intracellular Mg2+ on Ca2+ handling. In the present study, the effects of cytosolic-free Mg2+ concentration in the physiological (submillimolar) range on Ca2+ handling were investigated after stimulation of rat vascular smooth muscle cells with arginine vasopressin. Cytosolic Mg2+ was manipulated by culturing cells in medium containing different Mg2+ concentrations. Peak cytosolic-free Ca2+ concentration responses to arginine vasopressin (1 mumol/1) were measured in the presence and absence of external Ca2+. The results suggest that an increase in cytosolic-free Mg2+ concentration increases both Ca2+ discharge from intracellular stores and Ca2+ influx, whereas a decrease in intracellular Mg2+ attenuates Ca2+ influx.

Platelet Ca2+ is not increased in stroke-prone spontaneously hypertensive rats: comparative study with spontaneously hypertensive rats

We have reported that cytosolic Ca2+ concentration ([Ca2+]i) is increased in platelets from spontaneously hypertensive rats (SHR) in both basal and thrombin-stimulated conditions. To determine whether the correlation between blood pressure and cellular Ca2+ metabolism exists in stroke-prone SHR (SHRSP), we investigated Ca2+ handling using fura 2 and aggregation response in platelets of 12- to 13-week-old male SHRSP, SHR, and Wistar-Kyoto rats (WKY). Systolic pressure was highest in SHRSP and lowest in WKY (213 +/- 8, 172 +/- 7, and 135 +/- 5 mm Hg, respectively). Basal [Ca2+]i was significantly higher in SHR than WKY (45.9 +/- 4.5 versus 41.2 +/- 4.8 nmol/L, P<.05), and that in SHRSP (40.2 +/- 2.8 nmol/L) was similar to that in WKY. Thrombin (0.1 IU/mL)-stimulated [Ca2+]i rise was greater in SHR and smaller in SHRSP than in WKY in the presence of extracellular Ca2+ (530 +/- 50 and 408 +/- 52 versus 475 +/- 50 nmol/L, respectively; P<.05). The recovery rate from the peak [Ca2+]i response to thrombin was greatest in SHRSP and least in WKY. Ionomycin (5 micromol/L)-stimulated [Ca2+]i rise was similar in WKY, SHR, and SHRSP (731 +/- 97, 743 +/- 88, and 683 +/- 70 nmol/L, respectively). Thrombin-induced maximum platelet aggregation response was higher in SHR and lower in SHRSP than WKY (82 +/- 4 percent and 61 +/- 15 percent versus 73 +/- 6 percent, respectively; P<.05). In contrast to SHR, basal [Ca2+]i in SHRSP was similar to that in WKY, and thrombin-stimulated [Ca2+]i was attenuated. These result suggest that platelet Ca2+ handling differs between SHR substrains and that an increased [Ca2+]i is not obligatory in genetically hypertensive rats.

Enhancement of chemotherapeutic effects with focused shock waves: extracorporeal shock wave chemotherapy (ESWC)

The effects of shock waves in combination with various anti-cancer agents i.e. Bleomycin (BLM), Cisplatin (CDDP) and 5-fluorouracil (5-FU) on tumor cells suspended in media containing these agents were examined. GCIY cells derived from human gastric cancer and LS 174T and SW480 cells derived from human colon cancers were used for in vitro experiments; GCIY and SW480 cells were also transplanted into nude mice for in vivo study. It was only with BLM that enhancement was evident in all three cell lines, with a degree of chemotherapeutic enhancement proportional to the amount of shock wave energy applied. Ladder formation of DNA in GCIY cells was observed only when treated with both BLM and shock waves in combination. When SW480 and GCIY cells transplanted into the backs of nude mice were treated with a combination of intravenously (i.v.) injected BLM and regional exposure to shock waves, a significant enhancement of chemotherapeutic effects was observed in terms of the tumor growth curve.

Angiotensin I-converting enzyme gene polymorphism and salt sensitivity in essential hypertension

We undertook the present study in 66 Japanese patients with essential hypertension to identify genetic factors associated with salt sensitivity. Patients were classified into salt-sensitive or salt-resistant groups on the basis of changes in their mean blood pressures from a week of a low salt diet (50 mmol/d) to a week of a high salt diet (340 mmol/d). Salt sensitivity and resistance were studied in relation to a 287-bp insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme gene detected by a polymerase chain reaction method and the haptoglobin phenotype determined by polyacrylamide gel electrophoresis. Patients with the angiotensin I-converting enzyme gene genotype II were more apt to be salt sensitive than patients with the ID and DD genotypes, although plasma renin activity was similar in each group. The frequency of the I allele in the salt-sensitive group was significantly higher than that in the salt-resistant group (chi2 = 7.4, odds ratio = 2.78). However, there was no significant relationship between haptoglobin phenotype and salt sensitivity. These data suggest that an I/D polymorphism of the angiotensin I-converting enzyme gene is a genetic factor associated with salt sensitivity of blood pressure independently of plasma renin activity in Japanese patients with essential hypertension.

Non-invasive evaluation of abdominal aortic properties: lumped circuit model and estimation of its parameters

To non-invasively determine abdominal aortic properties, a five-element lumped circuit model was adopted. The model consists of resistance due to blood viscosity (R1), inertia of blood flow, compliances of the vessel (C1, C2), resistance of the peripheral arteries (R2) and the impedance of the of the femoral arteries (termination). Patterns of the central velocity of the upper abdominal aorta and the femoral artery are measured by pulsed Doppler echocardiography, and contours of flow volume rates are calculated. The pressure pattern of the lower limb is recorded by a pulse wave transducer and corrected according to sphygmomanometer values. Contours are transformed into respective Fourier transform components. The current transfer function is described theoretically and calculated from the acquired Fourier components. Values of every element are evaluated by the nonlinear least squares method. In 94 subjects (17-92 years), the values of each element are estimated. R2 values are greater in the elderly group than in the young group and r1 (R1/cm) increased with age. This model demonstrates that vessel compliance (C1 + C2 (C1 + C2/cm)) decreases with age, and it is suggested that this may be a useful marker of arteriosclerosis.

Effect of the transmembrane gradient of magnesium and sodium on the regulation of cytosolic free magnesium concentration in human platelets

1. To clarify the mechanism by which cytosolic free Mg2+ concentrations ([Mg2+]i) are regulated in human platelets, we investigated platelet membrane permeability to Mg2+ by altering extracellular Mg2+ concentrations, and tested the existence of a Na(+)-Mg2+ exchanger by manipulating the transmembrane Na+ gradient. 2. Platelet [Mg2+]i was 421 +/- 52 mumol/l in healthy men. [Mg2+]i remained constant during a 120 min exposure to nominally zero (low) or 5 mmol/l (high) external Mg2+ concentrations. 3. Preincubation of platelets with 10(-4) mol/l ouabain effectively decreased the transmembrane Na+ gradient. The ouabain-induced increase in [Mg2+]i was statistically significant after 30 min of exposure (14.6 +/- 2.0%) and reached 24.6 +/- 4.5% after 60 min. Similarly, the replacement of extracellular Na+ with N-methyl-D-glucamine significantly increased [Mg2+]i by 48.5 +/- 3.9% and 78.8 +/- 12.5%, respectively. 4. These results suggest that [Mg2+]i is well controlled in the presence of large transmembrane Mg2+ concentration gradients, and a Na(+)-Mg2+ exchanger may be involved in the regulation of [Mg2+]i in human platelets.

Intravenous administration of L-arginine inhibits angiotensin-converting enzyme in humans

The iv administration of L-arginine, a precursor of endothelium-derived relaxing factor/nitric oxide, is known to decrease blood pressure in humans by its direct vasodilatory effects. The purpose of the present study was to determine whether L-arginine infusion modifies the renin-angiotensin (Ang)-aldosterone system as well as blood pressure and renal hemodynamics. L-Arginine and saline vehicle were iv administered to 10 healthy male subjects in random order on different days. L-Arginine infusion (500 mg/kg over 30 min) decreased mean blood pressure (from 81.2 +/- 2.7 to 74.0 +/- 2.5 mm Hg; P < 0.001) and renal vascular resistance (from 0.085 +/- 0.007 to 0.074 +/- 0.006 mm Hg/mL.min; P < 0.01) and increased heart rate (from 60.3 +/- 2.7 to 69.7 +/- 2.1 beats/min; P < 0.001) and renal plasma flow (from 616.6 +/- 37.8 to 701.0 +/- 49.2 mL/min; P < 0.05). L-Arginine reduced serum Ang-converting enzyme activity (from 10.4 +/- 0.6 to 8.9 +/- 0.5 nmol/mL.min; P < 0.05) and plasma Ang-II (from 19.3 +/- 3.3 to 12.7 +/- 2.8 pg/mL; P < 0.001), but had no effect on PRA or the glomerular filtration rate. The saline vehicle did not alter any of these parameters. The iv administration of L-arginine (endothelium-derived relaxing factor/nitric oxide) may reduce the plasma Ang-II concentration by inhibiting Ang-converting enzyme. The mechanism by which L-arginine infusion decreases blood pressure can be at least in part explained by inhibition of the renin-Ang system.

Comparison of hypocholesterolemic effects induced by dietary linoleic acid and oleic acid in hamsters

We investigated the differences between the hypocholesterolemic effects induced by dietary linoleic acid and those induced by oleic acid in hamsters. Addition of 5% linoleic acid or oleic acid to a 0.1% cholesterol-supplemented diet diminished the increases in plasma total and low density lipoprotein (LDL) cholesterol induced by cholesterol alone. Linoleic acid decreased high density lipoprotein (HDL) cholesterol in comparison with cholesterol alone, whereas oleic acid did not. As compared with a standard diet or a cholesterol-supplemented diet, linoleic acid and oleic acid each prevented hepatic LDL receptor suppression, although linoleic acid was more effective. Oleic acid prevented the increase in plasma cholesteryl ester transfer protein (CETP) activity induced by dietary cholesterol, whereas linoleic acid did not. Neither linoleic acid nor oleic acid altered hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase activity. Only oleic acid increased hepatic cholesterol 7 alpha-hydroxylase activity. These results suggest that dietary linoleic and oleic acids diminish the cholesterol-induced increases in plasma total and LDL-cholesterol by preventing hepatic LDL receptor suppression, and in the case of oleic acid by also preventing the increase in the plasma CETP activity. These effects on cholesterol 7 alpha-hydroxylase activity may influence bile lipid metabolism.

Unrestricted T cell-mediated cytotoxicity to major histocompatibility antigen generated with tumor hybrid cells

Splenic T cells from C3H/He mice injected with the LFM3A#2 hybrid cells intraperitoneally (i.p.) showed cytotoxic activity against the parental FM3A/R tumor cells. We studied the target antigens recognized by cytotoxic T cells (CTL) and the following results were obtained. 1) CTL specifically recognized the MM antigens on the surface of target cells in effector phase. 2) The H-2K or H-2D antigens were not involved in T cell effector function.