The mechanism of lack of hypocholesterolemic effects of pravastatin sodium, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, in rats.

In order to clarify the reason why pravastatin, a 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor, did not show hypocholesterolemic effects in rats, the changes of various parameters affecting the serum cholesterol levels by pravastatin were determined in rats and rabbits, as a comparison. In rabbits, pravastatin administration at 50 mg/kg for 14 days decreased serum and liver cholesterol by 40% and 8%, respectively. The hepatic LDL receptor activity was increased 1.7-fold, and VLDL cholesterol secretion was decreased. Cholesterol 7 alpha-hydroxylase activity was not changed. In contrast, in rats, serum cholesterol was increased by 14% at 50 mg/kg and 27% at 250 mg/kg for 7 days, respectively. At 250 mg/kg, liver cholesterol was significantly increased by 11%. Under these conditions, neither the hepatic LDL receptor activity nor cholesterol 7 alpha-hydroxylase was changed, and VLDL cholesterol secretion was increased. At 250 mg/kg, net cholesterol synthesis in rat liver was increased after 7 days of consecutive administration. These results imply that in rats, stimulated net cholesterol synthesis caused the increase of liver cholesterol followed by the increase of VLDL cholesterol secretion, and resulted in the raise of plasma cholesterol. Although hepatic HMG-CoA reductase was induced almost the same fold in both animals at 50 mg/kg, the induced HMG-CoA reductase activity in rats might overcome the inhibitory capability of pravastatin, resulting in an increase of net cholesterol synthesis, but not in rabbits. This over response to pravastatin in rats might cause the lack of hypocholesterolemic effects of this drug.

Suppression of established atherosclerosis and xanthomas in mature WHHL rabbits by keeping their serum cholesterol levels extremely low. Effect of pravastatin sodium in combination with cholestyramine.

We investigated the possibility that established atherosclerosis and xanthomas in mature WHHL rabbits could be suppressed or even regressed when their serum cholesterol levels were kept extremely low. Ten-month-old WHHL rabbits were divided into 3 groups, i.e. control rabbits, sacrificed at age 10 months, and placebo and treated rabbits, sacrificed at age 18 months. The treated rabbits were given pravastatin sodium (50 mg/kg/day), an HMG-CoA reductase inhibitor, in combination with cholestyramine (2% in diet), a bile acid sequestrant, for 36 weeks. The serum cholesterol levels and atherogenic lipoproteins in the treated group were markedly reduced, by about 60% (P less than 0.005 and P less than 0.001). Consequently, the degrees of both coronary and aortic atherosclerosis in the treated group were significantly reduced compared with the placebo group, and were almost the same as in the control group. The histopathological findings supported the above results. In addition, the incidence and degree of xanthomas in digital joints in the treated group were significantly reduced. These results suggest that established atherosclerosis and xanthomas in mature WHHL rabbits could be suppressed by keeping their serum cholesterol levels extremely low by the combination drug treatment.

Spectrum of cardiovascular lesions in mucocutaneous lymph node syndrome: analysis of eight cases.

Eight cases of mucocutaneous lymph node syndrome with cardiovascular complications are described. The clinical presentation in all but one patient conformed to the previously described features of this syndrome. Five patients had cardiac enlargement, six had electrocardiographic abnormalities and three had a murmur of mitral insufficiency. Each of the four patients who died had aneurysms of the coronary arteries, usually associated with organizing thrombi. In addition to involvement of the coronary arteries, the renal, mesenteric, vertebral, splenic, hepatic and iliac arteries were affected to individual cases. One patient required triple aortocoronary bypass surgery and one patient underwent excision of a brachial arterial aneurysm. Further long-term follow-up studies of the patients who have survived the acute stage of the syndrome are indicated to establish this spectrum of late complications and sequelae.

The antioxidant effect of DL-alpha-lipoic acid on copper-induced acute hepatitis in Long-Evans Cinnamon (LEC) rats.

The Long-Evans Cinnamon (LEC) rats, due to a genetic defect, accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease and spontaneously develop acute hepatitis with severe jaundice. In this study we examined the protective effect of DL-alpha-Lipoic acid (LA) against acute hepatitis in LEC rats. LA was administered to LEC rats by gavage in doses of 10, 30 and 100 mg/kg five times per week, starting at 8-weeks-old and continuing till 12-weeks-old. Although LA had little effect against the increases in serum transaminase activities, it suppressed the loss of body weight and prevented severe jaundice in a dose-dependent manner. Antioxidant system analyses in liver showed that LA treatment significantly suppressed the inactivations of catalase and glutathione peroxidase, and the induction of heme oxygenase-1, an enzyme which is inducible under oxidative stress. Furthermore, LA showed dose-dependent suppressive effect against increase in nonheme iron contents of both cytosolic and crude mitochondrial fractions in a dose-dependent manner. Although at the highest dose, LA slightly suppressed the accumulation of Cu in crude mitochondrial fraction, it had no effect on the accumulation of Cu in cytosolic fraction. While LA completely suppressed the increase in lipid peroxidation (LPO) in the microsomal fraction at the highest dose, the suppressive effect against LPO in crude mitochondrial fractions was slight. From these results, it is concluded that LA has antioxidant effects at the molecular level against the development of Cu-induced hepatitis in LEC rats. Moreover, mitochondrial oxidative damage might be involved in the development of acute hepatitis in LEC rats.

Blood pressure levels in school-age Japanese children: the Hisayama Study.

Blood pressure (BP) measurements were obtained on a total of 6325 children (3294 boys and 3031 girls), aged 6-14 years, in Hisayama, Japan. All BPs were recorded in a sitting position by trained observers in a standardised manner. Standard mercury sphygmomanometers were used with commercially available cuffs, selected according to the arm circumference. Cuff size no. 3 (bladder width 9 cm, length 23 cm) was the one most commonly selected in 84% of elementary schoolers aged 6-11 years and in 35% of junior high schoolers aged 12-14 years. Mean systolic BPs (SBPs) increased from 89 mm Hg at age 6 years to 108 mm Hg at 14 years (a 21% increase) for boys and from 88 mm Hg to 102 mm Hg (a 16% increase) for girls. Diastolic BP (DBPs, Korotkoff phase IV, KIV) increased from ages 6 to 14 years to the same degree, from 58 mm Hg to 72 mm Hg (a 24% increase) for boys and from 58 mm Hg to 70 mm Hg (a 21% increase) for girls. The increase in DBP (Korotkoff phase V, KV) was greater, from 48 mm Hg to 63 mm Hg (a 30% increase) for boys and from 48 mm Hg to 61 mm Hg (a 28% increase) for girls. The increase in mean SBP for adolescent boys was greater compared with that of girls; however, separation of age-specific values by sex was not observed for mean DBP (KIV) and DBP (KV). The cross-sectional relation between age and mean SBP levels was not linear.

Troglitazone can prevent development of type 1 diabetes induced by multiple low-dose streptozotocin in mice.

Recent investigations suggest that cytotoxic cytokines such as tumor necrosis factor (TNF)alpha and interleukin (IL)-1beta or free radicals play an essential role in destruction of pancreatic beta cells in Type 1 diabetes and that, therefore, anti-oxidant or anti-TNF alpha and IL-1beta therapy could prevent the development of Type I diabetes. Troglitazone belongs to a novel class of antidiabetic agent possessing the ability to enhance insulin action provably through activating PPAR gamma and to scavenge free radicals. In the present study, we examined whether troglitazone can prevent the development of Type 1 diabetes in multiple, low-dose streptozotocin (MLDSTZ)-injected mice. In addition, effects of troglitazone on cytokine-induced pancreatic beta cell damage were examined in vitro. Type 1 diabetes was induced by MLDSTZ injection to DBA/2 mice (40 mg/kg/day for 5 days). Troglitazone was administered as a 0.2% food admixture (240 mg/kg/day) for 4 weeks from the start of or immediately after STZ injection. MLDSTZ injection elevated plasma glucose to 615 +/- 8 mg/dl 4 weeks after final STZ injection and was accompanied by infiltration of leukocytes to pancreatic islets (insulitis). Troglitazone treatment with MLDSTZ injection prevented hyperglycemia (230 +/- 30 mg/dl) and, suppressed insulitis and TNF alpha production from intraperitoneal exudate cells. TNF alpha (10 pg/ml) and IL-1beta (1 pg/ml) addition to hamster insulinoma cell line HIT-T15 for 7 days in vitro decreased insulin secretion and cell viability. Simultaneous troglitazone addition (0.03 to approximately 3 microM) significantly improved cytokine-induced decrease in insulin secretion and in cell viability. These findings suggest that troglitazone prevents the development of Type 1 diabetes in the MLDSTZ model by suppressing insulitis associated with decreasing TNF alpha production from intraperitoneal exudate cells and the subsequent TNF alpha and IL-1beta-induced beta cell damage.

Hepatic cytochrome P450 and flavin-containing monooxygenase in male Nts:Mini rat, a transgenic rat carrying antisense RNA transgene for rat growth hormone.

We investigated the characteristics of hepatic cytochrome P450s and flavin-containing monooxygenase 1 (FMO1) in male Nts:Mini rats, a Wistar/Jcl-derived transgenic rat strain showing less plasma GH concentration than the parental strain. The total hepatic P450 contents of Mini rats were significantly reduced. A suppression was observed in the activities and protein expression of male-specific P450s (CYP3A and CYP2C11) and was speculated to be a potential cause of the reduction in total P450 contents. The activity and protein expression of CYP2B1 were suppressed and those of CYP2E1 and CYP2B2 were enhanced. With the exception of our data on CYP2B1, these results largely agreed with previous reports concerning GH-depletion rat models (hypophysectomized rats, rats neonatally treated with glutamate, and dwarf rats), implying that the changes in Mini rats were caused by GH insufficiency. The liver FMO1 protein expression in Mini rats was higher than that in Wistar rats but the activity was comparable, suggesting that GH is not a positive regulator of FMO expression. With their insufficient but not depleted levels of plasma GH, Mini rats may thus become another candidate for use in the investigation of GH regulation of hepatic mixed-function monooxygenases.

The effects of R-75,317 on antiglomerular basement membrane glomerulonephritis in rats.

Platelet-activating factor (PAF) is a potent inflammatory mediator which is released by various inflammatory cells and produced by certain tissues, including the kidney. PAF has been shown to increase glomerular permeability to protein and to decrease glomerular filtration rate (GFR) by contracting mesangium. On the basis of these observations, it has been suspected that PAF may play a role as mediator of glomerular damage in glomerular nephritis. To examine this possibility, we studied the effects of a specific PAF antagonist, R-75,317, on the development of an experimental model of anti-glomerular basement membrane (anti-GBM) glomerulonephritis. Glomerulonephritis was initiated by injecting rabbit anti-rat GBM serum into rats. Proteinuria gradually developed after serum injection, plateaued at week 2, and remained at the high level of week 2 throughout the experimental period (6 wk). Chronic treatment with R-75,317 (10 mg/kg/day i.p.) tended to delay the onset of proteinuria and significantly accelerated the recovery phase. Creatinine clearance (Ccr) fell to 40% at week 3. R-75,317 treatment completely prevented this decline of Ccr. Histological changes in this model (glomerular hypertrophy, proliferation of mesangial matrix and interstitial fibrosis) were also ameliorated by the R-75,317 treatment. The results suggest that PAF may play a role in the development of glomerulonephritis and that PAF antagonists could be used in the treatment of human renal disease.

Postnatal exposure to chlorinated dioxins and related chemicals on lymphocyte subsets in Japanese breast-fed infants.

Effects of postnatal exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) on lymphocyte subpopulations were investigated in the peripheral blood of 36 breast-fed Japanese babies. As a result, estimated total intakes of these chemicals in toxic equivalent quantity (TEQ) converted into 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents from the breast milk positively and negatively correlated with the respective percentages of CD4+ and CD8+ lymphocytes in the blood of breast-fed babies. Consequently, the ratios of CD4+ to CD8+ T cells showed significant increasing tendency with the estimated total TEQ intakes. Therefore, our study suggests that exposure to background levels of the highly toxic organochlorine compounds through the breast milk influences the human neonatal immune system.

Postnatal exposure to chlorinated dioxins and related chemicals on thyroid hormone status in Japanese breast-fed infants.

Effects of postnatal exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) on thyroid hormone status were studied in the peripheral blood of 36 breast-fed Japanese infants. Estimated total intakes of these chemicals in toxic equivalent quantity (TEQ) converted into 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) from the breast milk significantly and negatively correlated with the levels of triiodothyronine (T3) and thyroxine (T4) in the blood of breast-fed babies. Therefore, exposure to background levels of the highly toxic organochlorine chemicals through the breast milk may cause some effects on thyroid hormone status in Japanese infants.

Life expectancy and social adaptation in individuals with Down syndrome with and without surgery for congenital heart disease.

Life expectancy and social adaptation in 373 children with Down syndrome with and without congenital heart disease (CHD) were assessed retrospectively. Survival at age 24 years was 92.2% for patients without CHD (n=200), and 74.6% for those with CHD (n=173). Survival for those who underwent operation for cardiovascular lesions (n=95) was 87.8%, and for those not operated on despite hemodynamically significant cardiovascular lesions (n=39), it was 41.4%. Cardiac functional capacity was better in the children without congenital heart disease and in the group operated on, where most patients also attained good social adaptation. We conclude that children with Down syndrome with congenital heart disease should undergo early cardiac evaluation and surgery if indicated.

Effect of dioxins in mother's milk on sister chromatid exchange frequency in infant lymphocytes.

Sister chromatid exchange (SCE) frequency which was an index to the synthetic and sharp genetic toxicity was examined using the infant lymphocyte cells around postnatal of 1 year. SCE frequency as the control culture which was treated with the solvent, DMSO, alone (SCEcontrol) was 8.2 +/- 0.9/cell and as cultured with 7,8-benzoflavone (ANF) (SCEANF) was 11.8 +/- 1.4/cell. In addition, the difference of SCEANF and SCEcontrol, namely, delta SCEs became 3.6 +/- 1.3/cell. The concentration of the dioxins in the mother's milk, which had taken by the infants, in the 2-4 month postpartum was 0.95 +/- 0.51 pg-TEQ/g in the male infants, and 0.97 +/- 0.48 pg-TEQ/g in the female ones. The sex difference could not be recognized in contamination levels of the dioxins in mother's milk. The SCE frequency of the infant lymphocytes was examined in order to evaluate the genetic toxicity of the dioxins which had contaminated mother's milk. As the result, either the SCE frequencies or delta SCEs did not show any significant correlation to the dioxins. Therefore, the dioxins were considered not to induce the genetic toxicity such as the SCEs at the present levels of pollution in Japanese mother's milk around postnatal of 1 year.

Spectrum of infective endocarditis during infancy and childhood: 20-year review.

The medical records of the 29 patients under 18 years of age with infective endocarditis (IE) seen over a 20-year period by our department were reviewed to provide an overview of the spectrum of IE during infancy and childhood. None of the 29 patients had had previous cardiovascular surgery. The mean age at onset of IE was 7 years 2 months; 3 patients (10%) were under 2 years of age at onset. One patient during the early years died following 4 months of treatment with various antibiotics. Three patients underwent urgent surgery, and 17 patients with healed IE had elective surgery. All of the 20 patients who were operated on survived. The remaining 8 were followed with medical treatment alone. Positive blood cultures were obtained from 24 (83%) patients, and streptococci were still commonly found (38%). Ventricular septal defect (VSD) accounted for 66% of underlying heart diseases and rheumatic heart diseases for 14%. Vegetations were detected in 12 (67%) of 18 patients observed by echocardiography. Among these 12 patients, 1 with VSD underwent urgent tricuspid valve replacement and VSD closure because of worsening congestive heart failure due to progressive tricuspid regurgitation. Echocardiography identifies patients at high risk with IE, though the presence of a vegetation on echocardiography does not necessarily of itself dictate surgical intervention.

Influence of upright activity on plasma renin activity and aldosterone concentration in children.

Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured in 156 healthy infants and children under basal conditions of normal diet and recumbency. PRA and PAC were also evaluated during and after stimulation of the renin-angiotension-aldosterone system by postural change. Basal values of PRA significantly declined with increasing age. Postural change by standing up resulted in an increase of PRA and PAC in all age groups. The increment of PRA but not of PAC was greater in older than in younger children. Neither the basal nor the stimulated levels of PRA and PAC were influenced by sex, body weight, body surface area, serum sodium, serum potassium, creatinine, and 24-h urine secretion of sodium and potassium. Both PRA and PAC returned to the basal levels within 60 min after resuming recumbent posture.

Influence of crying on plasma renin activity and aldosterone concentration.

Infants and toddlers often start crying at venopuncture and the stress of crying has been known to increase the levels of plasma renin activity (PRA) and plasma aldosterone concentration (PAC), but no precise information is available. We measured the levels of PRA and PAC in blood samples taken from 30 infants and toddlers within 1 min after the onset of crying, as induced by venopuncture, and 3 and 5 min after continuation of crying (PRA1.0, PRA3.0, PRA5.0, and PAC1.0, PAC3.0, PAC5.0). The age of these subjects ranged from 1 to 30 months (median 16 months). PRA1.0, PRA3.0 and PRA5.0 were 4.0 +/- 1.8 ng/ml per hour, 5.5 +/- 2.7 ng/ml per hour, and 7.8 +/- 4.2 ng/ml per hour, respectively. PAC1.0, PAC3.0 and PAC5.0 were 210 +/- 110 pg/ml, 231 +/- 118 pg/ml and 269 +/- 145 pg/ml, respectively. Both PRA and PAC increased with elapsing time. The increase in PRA was marked after a short episode of crying, but that in PAC was of a mild degree.

Atrial septal defects in neonates with reference to spontaneous closure.

Early diagnosis of atrial septal defects (ASDs) by means of two-dimensional echocardiography has facilitated studies on the natural course of this lesion. Among 12 Japanese infants in whom a diagnosis of opening of the atrial septum was made in the neonatal period, eight had spontaneous closure at age 2 to 16 months, as shown by two-dimensional echocardiography. To study the exact incidence and natural course of atrial openings in the neonatal period, another 102 consecutive infants from two neonatal care units were followed prospectively with the use of two-dimensional echocardiography. Atrial openings were evident in 24 infants (24%) within the first week of life, in 13 (13%) older than 1 week, in seven (7%) older than 1 month, in five (5%) older than 6 months, and in two (2%) older than 1 year. Twenty-eight of the 30 infants with spontaneous closure in both groups had valvelike openings of the atrial septum that closed by fusion of the valves. ASDs that closed spontaneously in infants with clinical signs and symptoms of atrial shunt may be the same clinical entity as the valvelike openings of the atrial septum frequently observed in neonates with few clinical symptoms and may be differentiated morphologically from ASDs with openings without valve formation, which have little tendency to close.