An HMG-CoA reductase inhibitor, cerivastatin, suppresses growth of macrophages expressing matrix metalloproteinases and tissue factor in vivo and in vitro

BACKGROUND

Unstable atherosclerotic plaques that cause acute coronary events usually contain abundant macrophages expressing matrix metalloproteinases (MMPs) and tissue factor (TF), molecules that probably contribute to plaque rupture and subsequent thrombus formation. Lipid lowering with HMG-CoA reductase inhibitors reduces acute coronary events.

METHODS AND RESULTS

To test whether lipid lowering with an HMG-CoA reductase inhibitor retards macrophage accumulation in rabbit atheroma, we administered cerivastatin to immature Watanabe heritable hyperlipidemic rabbits (cerivastatin group, n=10, cerivastatin 0.6 mg x kg(-1) x d(-1); control group, n=9, saline 0.6 mL x kg(-1) x d(-1)) for 32 weeks and measured macrophage accumulation and expression of MMPs and TF. Serum cholesterol levels after 32 weeks were 809+/-40 mg/dL (control group) and 481+/-24 mg/dL (treated group). Cerivastatin diminished accumulation of macrophages in aortic atheroma. Macrophage expression of MMP-1, MMP-3, MMP-9, and TF also decreased with cerivastatin treatment. Cerivastatin reduced the number of macrophages expressing histone mRNA (a sensitive marker of cell proliferation) detected by in situ hybridization but did not alter macrophages bearing a marker of death (TUNEL staining). Cerivastatin treatment (>or=0.01 micromol/L) also reduced growth, proteolytic activity due to MMP-9, and TF expression in cultured human monocyte/macrophages.

CONCLUSIONS

These results suggest that lipid lowering with HMG-CoA reductase inhibitors alters plaque biology by reducing proliferation and activation of macrophages, prominent sources of molecules responsible for plaque instability and thrombogenicity.

Adenosine-induced coronary flow reserve in Watanabe heritable hyperlipidemic rabbits

The Watanabe heritable hyperlipidemic (WHHL) rabbit develops coronary atherosclerosis and hypercholesterolemia because of a genetic deficiency of low-density lipoprotein receptors and is therefore a good animal model for studying the relationships of coronary atherosclerosis, hypercholesterolemia and coronary flow reserve. The aim of the present study was to assess myocardial perfusion at baseline and during adenosine infusion (0.2 mg x kg(-1) x min(-1)) in 8 WHHL rabbits (13.8+/-0.5 months) with 13N-ammonia, small-animal positron emission tomography (PET) and colored microspheres. Results were compared with those from 6 age-matched Japanese white rabbits. Plaque distribution was also examined in the extramural coronary arteries. All 8 WHHL rabbits had coronary plaques, with 6 showing multiple plaques. Mean global myocardial blood flow (ml x min(-1) x g(-1)) did not differ significantly between control and WHHL groups both at baseline (3.67+/-0.72 vs 4.26+/-1.12 ml x min(-1) x g(-1), p=NS) and with adenosine (7.92+/-2.00 vs 9.27+/-2.91 ml x min(-1) x g(-1), p=NS), nor did coronary flow reserve (2.16+/-0.37 vs 2.18+/-0.41, p=NS). None showed evidence of regional perfusion abnormalities by visual and semiquantitative analyses of PET images. It was concluded that WHHL rabbits preserve adenosine-induced coronary flow reserve despite coronary atherosclerosis and hypercholesterolemia, suggesting that a compensatory mechanism develops in this animal model.

Comparison of endothelium-dependent relaxation in carotid arteries from Japanese white and Watanabe heritable hyperlipidemic rabbits

Modifications by atherosclerosis of endothelium-dependent and -independent relaxations were evaluated in carotid arteries isolated from Watanabe heritable hyperlipidemic (WHHL; age 20-29 months) and age-matched Japanese white (JW) rabbits. Marked, patchy atherosclerotic lesions were observed in all WHHL rabbit arteries. Endothelium-dependent relaxations induced by acetylcholine, partly depressed by N(G)-nitro-L-arginine (L-NA), were significantly inhibited in the WHHL rabbit arteries with atherosclerosis, compared with those in the arteries without atherosclerotic lesions from JW and WHHL rabbits. No difference was observed in the relaxation caused by superoxide dismutase in these arteries. Conversely, endothelium-dependent relaxations by substance P were greater in the arteries with and without atherosclerosis from WHHL rabbits than in the arteries from JW rabbits. Endothelium-independent relaxations elicited by sodium nitroprusside and 2,2-(hydroxynitrosohydrazino)bis-ethanamine (NOC18) did not differ in the arteries from JW and WHHL rabbits. The responses to acetylcholine and substance P of JW rabbit arteries with the endothelium were not attenuated by treatment with pertussis toxin. L-NA-resistant, endothelium-dependent relaxations by substance P were almost abolished by charybdotoxin, and atherosclerosis did not alter the response. It is concluded that endothelial functions, evaluated by substance P, in rabbit carotid arteries are not impaired by atherosclerosis and by long exposure to hyperlipidemia in vivo. Dysfunction of muscarinic receptors may be involved in the depressed response to acetylcholine. As far as the arteries used in the present study are concerned, responses mediated possibly by endothelium-derived hyperpolarizing factor (EDHF) are unlikely to be modulated by atherosclerosis.

[1-11C]Octanoate as a PET tracer for studying ischemic stroke: evaluation in a canine model of thromboembolic stroke with positron emission tomography

Octanoate is taken up by the brain and converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. Consequently, [1-11C]octanoate might serve as a useful positron emission tomography (PET) probe for studying cerebral oxidative metabolism and/or astroglial functions. The present study attempted to evaluate the utility of using [1-11C]octanoate as a PET tracer for imaging and evaluating the pathophysiology of ischemic stroke. We used a canine model of thromboembolic stroke. Five male beagle dogs were implanted with an indwelling catheter in the left internal carotid artery. A single autologous blood clot was injected into the left internal carotid artery through the catheter. The brain distribution of [1-11C]octanoate and cerebral blood flow (CBF) were determined 24 h after insult using a high resolution PET scanner. Post mortem brain regions unstained with 2,3,5-triphenyltetrazolium chloride (TTC) were defined as infarcts. In the region of an infarct, accumulation of [1-11C]octanoate decreased concurrently with CBF reduction. In contrast, normal accumulation of [1-11C]octanoate was observed in ischemic but vital regions, suggesting that an increased accumulation of [1-11C]octanoate relative to CBF takes place in these regions. In conclusion, [1-11C]octanoate accumulated in ischemic but vital regions, indicating that [1-11C]octanoate is a potentially useful PET tracer for imaging and evaluating the pathophysiology of ischemic stroke.

Defects of the LDL receptor in WHHL transgenic rabbits lead to a marked accumulation of plasma lipoprotein[a]

In this study, we created LDL receptor (LDLr) defective (WHHL) transgenic rabbits expressing human apo[a] to examine whether LDLr mediates the Lp[a] clearance from the plasma. By crossbreeding WHHL rabbits with human apo[a] transgenic rabbits, we obtained two groups of human apo[a] transgenic rabbits with defective LDLr functions: apo[a](1/0) WHHL heterozygous (LDLr(+/-) and apo[a](+/0) WHHL homozygous (LDLr(-/-) rabbits. The lipid and lipoprotein levels of human apo[a] WHHL rabbits were compared to those of human apo[a] transgenic rabbits with normal LDLr functions (LDLr(+/+). The apo[a] production rate was evaluated by analyzing apo[a] mRNA expression in the liver, the major site for apo[a] synthesis in transgenic rabbits. We found that pre-beta lipoproteins were markedly increased accompanied by a 2-fold increase in the plasma Lp[a] in apo[a](+/0)/LDLr(+/-) rabbits and a 4.2-fold increase in apo[a](+/0)/LDLr(-/-) rabbits compared with that in apo[a](+/0) rabbits with normal LDLr function. In apo[a](+/0)/LDLr(-/-) rabbits, there was a marked increase in plasma total cholesterol and triglycerides, as was found in their counterpart non-transgenic WHHL rabbits. Northern blot analysis revealed that hepatic apo[a] expression in WHHL transgenic rabbits was similar to that in LDLr(+/+) transgenic rabbits, suggesting the accumulation of plasma Lp[a] in WHHL transgenic rabbits was not due to increased apo[a] synthesis. In conclusion, absence of a functional LDLr leads to a marked accumulation of plasma Lp[a] in human apo[a] transgenic WHHL rabbits and LDLr may participate in the catabolism of Lp[a] in rabbits.

Age-associated decrease in plasma cholesterol and changes in cholesterol metabolism in homozygous Watanabe heritable hyperlipidemic rabbits

We examined the cholesterol metabolism of homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model deficient in low-density lipoprotein (LDL) receptors, to clarify the mechanism of the age-associated decrease of plasma total cholesterol, one of the properties of WHHL rabbits. The rabbits were examined at several ages: after weaning at 3 months, at sexual maturation at 6 months, at 12 months, and at 24 months, equivalent to about 35 years of age in humans. Plasma total cholesterol, triglyceride, and phospholipid levels decreased with aging by about 45%. These reductions were mainly dependent on a decrease in the LDL fraction. In the liver microsomal fraction, although there were no age-related changes in the cholesterol concentration and cholesterol 7alpha-hydroxylase (C7H) activity, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity increased and acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity decreased with aging. The lipolytic activity varied with aging. The secretion rate of very-low-density lipoprotein (VLDL) cholesterol as determined by injection of Triton WR-1339 decreased significantly with aging, while the catabolic rate of VLDL cholesterol was about 2-fold higher in the oldest group versus the young groups. From these results, we conclude that the age-associated decrease in plasma cholesterol in WHHL rabbits is related not only to a decrease in the secretion rate of VLDL cholesterol but also to an increase in the catabolic rate.

Preliminary evaluation of [1-11C]octanoate as a PET tracer for studying cerebral ischemia: a PET study in rat and canine models of focal cerebral ischemia

Octanoate is taken up into the brain and is converted in astrocytes to glutamine through the TCA cycle after beta-oxidation. We speculate that [1-11C]octanoate may be used as a tracer for astroglial functions and/or fatty acid metabolism in the brain and may be useful for studying cerebral ischemia. In the present study we investigated brain distribution of [1-11C]octanoate and compared it with cerebral blood flow (CBF) by using rat and canine models of middle cerebral artery (MCA) occlusion and a high resolution PET. In rats brain distribution of [15O]H2O measured 1-2 h and 5-6 h after insult was compared with that of [1-11C]octanoate measured 3-4 h after insult. Radioactivity ratios of lesioned to normal hemispheres determined with [15O]H2O were lower than those determined with [1-11C]octanoate. These results were confirmed by a study on a canine model of MCA-occlusion. Twenty-four hours after insult, CBF decreased in the MCA-territory of the occluded hemisphere, whereas normal or higher accumulation of [1-11C]octanoate was observed in the ischemic regions. The uptake of [1-11C]octanoate-derived radioactivity therefore increased relative to CBF in the ischemic regions, indicating that [1-11C]octanoate provides functional information different from CBF. In conclusion, we found that [1-11C]octanoate is a potential radiopharmaceutical for studying the pathophysiology of cerebral ischemia.

Exacerbation of herpes simplex encephalitis after successful treatment with acyclovir

Herpes simplex encephalitis (HSE) in children sometimes exacerbates after successful treatment; yet the frequency, etiology, and clinical features of exacerbation remain unclear. We report data for 27 children with HSE confirmed by polymerase chain reaction (PCR) analysis; all were successfully treated with acyclovir, but 7 (26%) had a relapse of encephalitic illness. In 2 of those 7, serial examination with a PCR assay showed that herpes simplex virus (HSV) DNA reappeared temporarily in the cerebrospinal fluid (CSF). For 5 of the 7 patients, a second course of acyclovir therapy was effective. Coxsackievirus A9 was isolated from CSF of 1 case patient during subsequent exacerbation. The total dose during initial acyclovir therapy was significantly lower in the relapse group than in the control group (P=.027). In conclusion, exacerbation of HSE in children may be more common than previously recognized. It is suggested that the replication of HSV or another viral pathogen caused a second encephalitic illness (HSE) in some cases.

Radioprotective effects of sodium tungstate on hematopoietic injury by exposure to 60Co gamma-rays in Wistar rats

Radioprotective effects of sodium tungstate (ST) on 60Co gamma-ray induced decrease in hematocrit value and in survival rate in Wistar strain male rats were examined. A long-term administration of ST (less than 150 mg/kg body weight/day) for 60-300 days had no significant effects on body and organs weights and survival days. The LD50/60 in 20 weeks old rats was 220 mg/kg body weight/day. Daily administration of 38, 75 or 150 mg from 7 days before and after irradiation to 60 days significantly mitigated the decrease in hematocrit values, especially at 23 days after irradiation (P < 0.05). The highest mitigation rate of the decrease in hematocrit value was observed in rats administered at a dose of 38 mg ST/day. Simultaneously, a dose of 38 mg ST/day inhibited lethal effect of 60Co gamma-rays significantly. The dose-reduction factor for survival of 38 mg ST administered rats was 1.14.

Granulocyte-macrophage colony-stimulating factor prevents the progression of atherosclerosis via changes in the cellular and extracellular composition of atherosclerotic lesions in watanabe heritable hyperlipidemic rabbits

BACKGROUND

A cytokine network is involved in atherogenesis. This study was conducted to investigate the effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the development and composition of atherosclerotic lesions in Watanabe heritable hyperlipidemic (WHHL) rabbits.

METHODS AND RESULTS

GM-CSF (10 microg. kg-1. d-1) was administered to 4-month-old WHHL rabbits (n=9) 5 days a week for 7.5 months, whereas an equal dose of human serum albumin was administered to controls (n=9). The cholesterol levels were not changed significantly by the treatment. Age-matched 4-month-old rabbits (n=7) had atheromatous plaques over 30.7+/-5.7% of the inner surface area of the aortic arch. After treatment, the percentages of surface atheromatous plaques to total aortic arch area were 45.0+/-12.6% in the GM-CSF group and 74.3+/-11.0% in controls (P<0.0001). Histological examination demonstrated that GM-CSF reduced the ratio of intima to media (P<0.01) and cross-sectional areas of atherosclerotic lesions (P<0.0001). Quantitative analysis indicated a marked decrease in the areas of smooth muscle cells (P=0.0001), collagen (P=0.0001), and extracellular lipid deposits (P<0.05) of atheromatous plaques in GM-CSF-treated rabbits compared with controls. The terminal deoxynucleotidyltransferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method and immunohistochemistry were performed to examine the relationship between decreased atherosclerotic lesions and apoptosis. The percentage of TUNEL-positive cells increased in the GM-CSF group (GM-CSF, 24.1+/-4.4% versus control, 11.6+/-3.2%; P<0.0001). GM-CSF enhanced the apoptosis of smooth muscle cells in the shoulder region and the fibrous cap (P<0.0001), suggesting one of the mechanisms for the antiatherogenic effect.

CONCLUSIONS

GM-CSF altered the composition of atherosclerotic lesions and reduced the atherosclerosis in WHHL rabbits.

Effect of early oral fluoroquinolones in hemorrhagic colitis due to Escherichia coli O157:H7

During the Sakai outbreak of Escherichia coli O157:H7 infection, which was linked to contaminated cafeteria school lunches, there were several treatment modalities with regard to antimicrobial drugs. Patient outcomes among three hospitals with different modalities were compared retrospectively. Hemolytic uremic syndrome did not develop in any of the 15 patients treated with oral fluoroquinolone therapy; however, HUS did develop in three of 15 patients treated with intravenous (i.v.) fosfomycin and in two of 12 patients treated with i.v. cefotaxime and oral fosfomycin. The results indicate that oral fluoroquinolone therapy administered within 3 days of illness is effective in preventing the development of HUS; however, prospective randomized double-blind studies on early antimicrobial therapy of O157 hemorrhagic colitis are necessary. Several antibiotics, including fluoroquinolones, were reported to induce the production or release of Shiga-like toxins (STX) from E. coli O157:H7 in vitro. Although patients were examined for fecal STX, no STX were detected in the stools of patients treated with oral fluoroquinolones. In fact, treatment with fluoroquinolones for 5 days eradicated E. coli O157 in all patients.

Combination treatment with troglitazone, an insulin action enhancer, and pravastatin, an inhibitor of HMG-CoA reductase, shows a synergistic effect on atherosclerosis of WHHL rabbits

We examined whether improving insulin resistance augments the antiatherosclerotic effect of LDL reduction. Since WHHL rabbits show hyperinsulinemia and insulin resistance, we administered troglitazone (100 mg/kg), an insulin action enhancer, pravastatin sodium (50 mg/kg), an HMG CoA reductase inhibitor, and a combination of both drugs to 2-month-old WHHL rabbits for 32 weeks. As compared to the control, total cholesterol levels in the plasma and LDL were decreased significantly by 20% in the pravastatin and combination groups. Basal immunoreactive insulin levels and insulin index were decreased significantly by approximately 50% in the troglitazone and combination groups. Surface lesion area of atherosclerosis on the thoracic aorta was decreased significantly by 36% in the combination group and was less in the troglitazone group. Coronary atherosclerosis was decreased significantly by 39% in the combination group and was less in the pravastatin and troglitazone groups. The collagen content in the plaques was decreased in the troglitezone and combination groups and the extracellular lipid deposits were decreased in the pravastatin and combination groups. The incidence and severity of xanthomata in the digital joints were also decreased significantly in the three treated groups. In conclusion, the antiatherogenic effect of the combination treatment is stronger than that of the monotherapy.

Neopterin Concentrations of Serum and Cerebrospinal Fluid in Febrile Convulsion, Aseptic Meningitis and Influenza Encephalopathy

The concentration of total neopterin in serum and cerebrospinal fluid (CSF) was measured in cases of febrile convulsion, aseptic meningitis and influenza encephalopathy. In febrile convulsion except for exanthem subitum, the concentrations of CSF neopterin (26± 11, Mean±SD, n=6) were all within normal range while those of serum neopterin (66± 20, n=8) were significantly higher (p < 0.05). In aseptic meningitis, on the other hand, the concentrations of CSF neopterin (194± 130, n=13) were significantly higher than those of serum (33±23, n=11, p < 0.05). In influenza encephalopathy, both concentrations of serum neopterin (329±478, n=13) and CSF neopterin(179±131, n=11) were much higher than the control range. Our results indicate that the primary immunoreacting site is the central nervous system (CNS) for aseptic meningitis, the periphery for febrile convulsion except for exanthem subitum and both the periphery and the CNS for influenza encephalopathy. Measurements of neopterin concentrations in CSF as well as in serum may thus constitute an immediate aid for early differentiation of CNS infection from peripheral infection as well as for early detection of viral encephalopathy caused by viruses such as the influenza virus or the human herpes virus 6.

Effect of cerivastatin sodium, a new inhibitor of HMG-CoA reductase, on plasma lipid levels, progression of atherosclerosis, and the lesional composition in the plaques of WHHL rabbits

1. The aim of this study was to examine whether cerivastatin sodium, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, affects the lesional composition of spontaneously developed atherosclerosis due to hypercholesterolaemia and delays progression of the lesions. 2. We administered cerivastatin to 2-month-old WHHL rabbits, a low-density lipoprotein receptor-deficient animal model, at a dose of 0.6 mg kg(-1) day(-1) for 32 weeks. We examined the plasma lipid levels, the severity of atherosclerosis, and composition of atherosclerotic lesions. Lesional composition was determined using immunohistostaining for macrophages and smooth muscle cells, and Azan-Mallory staining for collagen fibres and extracellular lipid deposits. 3. Compared to the control group, the plasma cholesterol levels were decreased in the treated group by 39% (12.7+/-0.6 mmol L(-1) versus 20.9+/-1.0 mmol L(-1), P<0.001). Atherosclerosis was suppressed by about 37% as measured by the thickness of the aortic lesions (158+/-13 microm versus 250+/-15 microm, P<0.001), and by 28% as measured by coronary stenosis (62.7+/-11.4 versus 86.9+/-12.2, P<0.05). In the cerivastatin group, regarding the per cent areas of lesional components in the lesion area, the macrophages (21.0+/-1.5% versus 27.9+/-1.9%, P<0.01) and extracellular lipid deposits (3.2+/-0.4% versus 5.1+/-0.4%, P<0.001) were decreased in the aortic lesions, and the per cent area of macrophages in the coronary lesions was also decreased (4.9+/-1.4% versus, 11.6+/-2.4%. P<0.05). The per cent area of smooth muscle cells and collagen fibres did not significantly decrease. 4. These results indicate that cerivastatin contributed to the plaque stabilization and delayed progression of early atherosclerosis in young WHHL rabbits, in addition to the potent hypolipidemic effects.

An additional variant of the persistent primitive trigeminal artery: accessory meningeal artery--antero-superior cerebellar artery anastomosis associated with moyamoya disease

Persistent embryological carotid-basilar anastomoses are rare. There has been no report on persistent anastomosis between the accessory meningeal artery and the antero-superior cerebellar artery. We describe a 3-year-old boy with moyamoya disease manifesting such a congenital vascular anomaly, namely, a large anastomosis between the accessory meningeal artery and the antero-superior cerebellar artery associated with marked hypoplasia of the basilar artery. This persistent vascular anomaly is considered embryologically as an additional variant of the persistent primitive trigeminal artery, i.e., a "stapedo-trigemino-cerebellar" variant.

Morphological Study of Carotid Artery of WHHL Rabbit after Balloon Dilatation

SUMMARY

We performed balloon dilatation in the carotid artery of WHHL rabbits and examined subsequent morphological alteration over time. The balloon was inserted as far as the carotid bifurcation and observations were made on the morphological alteration after dilatation in the atherosclerotic intimal thickening from immediately after balloon dilatation over a period of ten months. Immediately after balloon dilatation, endothelial cells came of circularly and stretching, fragmentation off elastic fibers and coming off of smooth muscle cells of the media were confirmed. No change in the degree of thickening after dilatation was seen in the atherosclerotic intimal thickening of the carotid bifurcation. Three weeks later, endothelium covering except some parts, circular neointima and fibrosis of the media were observed; foamy cells had accumulated in the upper layer of the atherosclerotic intimal thickening, and that region was not yet covered with endothelial cells. The progress of fibrous intimal thickening so as to keep the lumen smooth was seen up to six months later, but foamy cells were not found in the neointima.

Encephalopathy and cytomegalovirus colitis in an AIDS child

A 2-year-old girl, who had prolonged thrush and spastic diplegia, was found to have a mother-to-child vertical transmission of human immunodeficiency virus type-1 (HIV). A brain computed tomography scan revealed a symmetrical calcification on the bilateral basal ganglia and periventricular white matter. She had an acquired immune deficiency syndrome (AIDS) encephalopathy of pure dominant pyramidal tract disorder without an intellectual deficit. Helper cell lymphocyte count (CD4) increased with the beginning of zidovudine (ZDV, also known as AZT) monotherapy but began to decrease after the 4th week to reach the baseline at 20th week. Zidovudine plus didanosine combination therapy was started at the 68th week, but because of intolerance, the combination was changed to ZDV plus lamivudine at the 98th week. By the 80th week, neither severe opportunistic infection nor deterioration of the neurological status was recognized, but chronic diarrhea appeared. The diarrhea advanced to the wasting syndrome at the age of 4 years and cytomegalovirus genome was confirmed in a biopsied specimen of the colon. Ganciclovir treatment was effective in stopping the diarrhea and increasing her bodyweight, but after the age of 5, resumption of diarrhea was followed by progressive emaciation and weakness. This work may provide some clues in treating children's AIDS.

[Application of a semi-automatic ROI setting system for brain PET images to animal PET studies]

ProASSIST, a semi-automatic ROI (region of interest) setting system for human brain PET images, has been modified for use with the canine brain, and the performance of the obtained system was evaluated by comparing the operational simplicity for ROI setting and the consistency of ROI values obtained with those by a conventional manual procedure. Namely, we created segment maps for the canine brain by making reference to the coronal section atlas of the canine brain by Lim et al., and incorporated them into the ProASSIST system. For the performance test, CBF (cerebral blood flow) and CMRglc (cerebral metabolic rate in glucose) images in dogs with or without focal cerebral ischemia were used. In ProASSIST, brain contours were defined semiautomatically. In the ROI analysis of the test image, manual modification of the contour was necessary in half cases examined (8/16). However, the operation was rather simple so that the operation time per one brain section was significantly shorter than that in the manual operation. The ROI values determined by the system were comparable with those by the manual procedure, confirming the applicability of the system to these animal studies. The use of the system like the present one would also merit the more objective data acquisition for the quantitative ROI analysis, because no manual procedure except for some specifications of the anatomical features is required for ROI setting.

Effect of fluvastatin sodium on the smooth muscle cells in atherosclerotic plaques. In vivo study using low-density lipoprotein receptor deficient Watanabe heritable hyperlipidemic (WHHL) rabbits

The effects of fluvastatin sodium (CAS 93957-55-2, XU 62-320), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on the smooth muscle cells in the atherosclerotic plaques of Watanabe heritable hyperlipidemic (WHHL) rabbits, a low density lipoprotein (LDL) receptor deficient animal model, were examined. Fluvastatin was administered to WHHL rabbits for 32 weeks at a dose of 50 mg/kg of body weight. The control WHHL rabbits were administered distilled water as placebo. Compared to the control group, the total cholesterol levels in the sera, very low density lipoprotein, intermediate density lipoprotein, and LDL decreased by 34%, 72%, 63%, and 25%, respectively. Although the surface lesion area of the aorta in the treated group was not different from that in the control group, intimal thickening in the treated group was significantly lower than that in the control group. Of the lesional components of atherosclerosis, the relative area of smooth muscle cells, collagen fibers, and extracellular lipid deposits in the treated group decreased significantly. It is concluded that fluvastatin decreased in the smooth muscle cell content of the atherosclerotic plaques and delayed progression of the aortic atherosclerosis in addition to the potent hyperlipidemic effect.

Nitric oxide suppression reversibly attenuates mitochondrial dysfunction and cholestasis in endotoxemic rat liver

This study aimed to examine whether nitric oxide (NO) plays a causal role in endotoxin-induced dysfunction of biliary transport. Rats were treated with intraperitoneal injection of endotoxin (O111B4, 4 mg/kg). At 2 hours, the liver was excised and perfused ex vivo with taurocholate (TC)-containing Krebs-Ringer solution under monitoring bile output and NO2 in the perfusate and tissue cyclic guanosine monophosphate (cGMP) levels as indices of NO production. The endotoxin treatment evoked a marked decrease in the bile acid-dependent bile formation concurrent with the increasing NO2 output, cGMP elevation, and a reduction of hepatic adenosine triphosphate (ATP) contents and oxygen consumption. Perfusion with 1 mmol/L aminoguanidine (AG), an inhibitor of inducible NO synthase, but not with L-nitroarginine methyl ester, an inhibitor of the constitutive form of the enzyme, significantly reversed the endotoxin-induced increment of the bile formation in concert with the recovery of oxygen consumption and ATP levels. Laser confocal microfluorography of the liver lobules using rhodamine 123 (Rh), a fluoroprobe sensitive to mitochondrial membrane potential, revealed that endotoxin elicited a significant mitochondrial dysfunction panlobularly. The AG administration reversed the endotoxin-induced decrease in mitochondrial membrane potential. Collectively, up-regulation of NO by inducible NO synthase accounts for a mechanism through which endotoxin impairs the bile formation, and its suppression serves as a therapeutic strategy for improvement of hepatobiliary function.

Effect of macrophage colony stimulating factor on the advanced atherosclerosis in Watanabe heritable hyperlipidemic rabbits

We have reported that macrophage colony-stimulating factor (M-CSF) prevents atherosclerosis in young WHHL rabbits (Atherosclerosis 93:245, 1993). In the present study, we injected recombinant human M-CSF (250 micrograms/day) into WHHL rabbits aged 11 months 3 times a week after advanced atherosclerosis was established. After 8 months of treatment, we did not find any significant difference in plasma lipid levels, cholesterol ester content in the aorta or macroscopic atherosclerosis lesion area between M-CSF treated and non-treated rabbits. There was, however, a significant difference in the ratio of intimal to medial thickness (1.08 vs 1.7, p < 0.01). Thus, M-CSF may influence vascular smooth muscle cell function and modify the process of atherosclerosis in advance lesions.

Zonisamide monotherapy in newly diagnosed infantile spasms

PURPOSE

We determined the short-term efficacy of zonisamide (ZNS) monotherapy in newly diagnosed patients with infantile spasms (IS).

METHODS

Eleven hospitals participated in this open, prospective trial. ZNS 3-10 mg/kg/day was administered as the second-choice drug to 11 newly diagnosed patients with IS (cryptogenic 3, symptomatic 8) who failed to respond to high-dose vitamin B6.

RESULTS

Four infants with symptomatic IS had cessation of spasms and disappearance of the hypsarrhythmia. In these responders, the spasms ceased after a few days (1-5 days) of treatment at a dose of ZNS 4-5 mg/kg/day which produced plasma ZNS concentrations ranging from 5.2 to 16.3 microg/ml (mean 9.8 microg/ml). There were two relapses (50%) 4-6 weeks after cessation of seizures, however. Relapse was predicted by effects of ZNS on EEG; the 2 infants in whom an abnormal EEG persisted had relapses, whereas the 2 whose EEG normalized remained seizure-free (follow-up 20 and 26 months). No adverse reactions were noted.

CONCLUSIONS

ZNS may be effective in the initial treatment of selected patients with IS.

Endogenous carbon monoxide suppression stimulates bile acid-dependent biliary transport in perfused rat liver

This study aimed to investigate whether carbon monoxide (CO), a product of heme oxygenase that degrades protoheme IX, serves as an endogenous modulator for biliary transport. To that end, effects of zinc protoporphyrin IX (ZnPP), a heme oxygenase inhibitor, on the biliary transport were tested in perfused rat liver. Perfusion of 1 microM ZnPP abolished detectable levels of CO in the venous perfusate and increased bile acid-dependent bile output accompanying an increased secretion of bile salts. The ZnPP-induced choleresis coincided with a reduction of tissue guanosine 3',5'-cyclic monophosphate (cGMP) levels and a decrease in vascular conductance. On administration of 2.5 microM CO, ZnPP-elicited choleresis, decreases in vascular conductance, and cGMP levels were all attenuated. Treatment with 1 microM 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) partly attenuated the ZnPP-induced choleresis in concert with repression of vascular conductance. Furthermore, treatment of the liver with methylene blue, a guanylate cyclase inhibitor, evoked a choleresis similar to that induced by ZnPP. Thus endogenous CO suppression stimulates the biliary transport in part through a cGMP-dependent mechanism.

[Sporadic cases of hemolytic uremic syndrome and hemorrhagic colitis with serum IgM antibodies to lipopolysaccharides of enterohemorrhagic Escherichia coli O157]

In 1994-1996 summer, eight patients with hemolytic uremic syndrome(HUS) and 3 patients with hemorrhagic colitis, whose fecal specimens yielded no Enterohemorrhagic Escherichia coli(EHEC) because of the antibiotic therapies before presentation, showed serum IgM antibody responses to lipopolysaccharide(LPS) of O157. Although early bacteriological examination is essential for diagnosis, serological testing of patients with HUS or HC for antibodies to the LPS of EHEC provides evidence of infection with EHEC. We also presented successful fluoroquinolones(SPFX and NFLX) therapies of another 15 HC inpatient cases from Sakai outbreak of O157 infections due to school lunch in summer 1996. In these 15 HC patients, 12 EHECs of serotype O157:H7 with VT1 and VT2 and phage type 32 were obtained, but no growths of EHECs after fluoroquinolones therapy and no progressions to HUS resulted. The MICs of SPFX is 0.025 microgram/dl, NFLX 0.1, NA 3.13, FOM 12.5, ST 0.39, KM 3.13, ABPC 1.56-3.13.

A novel de novo mutation in HPRT gene responsible for Lesch-Nyhan syndrome (HPRT OSAKA)

A virtually complete deficiency of hypoxanthine guanine phosphoribosyltransferase (HPRT) causes Lesch-Nyhan syndrome. A novel mutation of HPRT gene in a Japanese Lesch-Nyhan family has been identified using mRNA and genomic DNA from peripheral blood cells. A single nucleotide substitution of T to C in exon 3 resulted in a mis-sense mutation, CTC (Leu) to CCC (Pro), at codon 65. Utilizing an Mn/I restriction site which was lost in the mutation as an indicator, a family study showed that the mother was normal not having the mutant gene. The mutation was a de novo event that had occurred in the germ cells of the mother or in the proband during the early phase of fetal development.

Expression of very low density lipoprotein receptor mRNA in rabbit atherosclerotic lesions

The expression of very low density lipoprotein (VLDL) receptor mRNA in atherosclerotic lesions in rabbits was investigated. To examine the expression of the VLDL receptor in the vascular wall, poly(A)+ RNA was isolated from whole aortas of cholesterol-fed New Zealand White (NZW), Watanabe heritable hyperlipidemic (WHHL), and normal NZW rabbits, and then Northern blot analysis was performed. The VLDL receptor mRNA was detected in aortas from both NZW rabbits fed 0.5% cholesterol for 16 weeks and 12-month-old WHHL rabbits, whereas no expression was seen in normal NZW rabbit aortas. To further determine the localization of the VLDL receptor mRNA, in situ hybridization using digoxigenin-labeled riboprobes and immunohistochemistry using monoclonal antibodies against each cell component were performed. Early atherosclerotic lesions, termed fatty streaks, in the NZW rabbits fed 0.5% cholesterol for 4 weeks demonstrated strong expression of the VLDL receptor mRNA by macrophages. The VLDL receptor mRNA was also expressed in more advanced atherosclerotic lesions from both atherogenic animal models. The predominant origin of the VLDL receptor mRNA-positive cells was macrophages, and some intimal smooth muscle cells appeared to express a weak but significant signal in these advanced lesions. Our findings suggest that the VLDL receptor expression may play a role in the development of atherosclerosis.

General pharmacological properties of the new angiotensin II receptor antagonist (+/-)-1-(cyclohexyloxycarbonyloxy) ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl] methyl]-1 H-benzimidazole-7-carboxylate. Part II: Effect on cardiovascular system and renal functions

The effects of TCV-116 ((+/-)-1-(cyclohexyloxycarbonyloxy) ethyl 2-ethoxy-1-[[2'-(1 H-tetrazol-5-yl)biphenyl-4-yl] methyl]-1 H-benzimidazole-7-carboxylate, CAS 145040-37-5) on the cardiovascular system and renal function were investigated in rats, guinea pigs, and dogs. TCV-116 at doses of 3 mg/kg (i.d.) and higher markedly increased renal blood flow in anesthetized dogs. TCV-116 at 30 mg/kg (i.d.) had no effect on heart rate, left ventricular systolic pressure, its dp/dtmax, or cardiac output in anesthetized dogs. Furthermore, TCV-116 at 10 and 30 mg/kg (p.o.) had little effect on cardiac output, right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure or respiration in conscious dogs. In isolated guinea pig perfused heart, CV-11974 even at a dose of 0.1 mg/ heart had no effect on cardiac function. In isolated guinea-pig atria, CV-11974, the active metabolite of TCV-116, even at 10(-4) mol/l had no effect on the spontaneous beating rate of the right atria or the contractile force of electrically-paced left atria. No significant effect of TCV-116 on urinary volume or urinary excretion of sodium and potassium was observed in rats (at 30, 100 or 300 mg/kg p.o.). These findings suggest that TCV-116 exerts no any additional pharmacological effects on cardiac and respiratory functions in dogs or on renal function in rats, other than an increase in renal blood flow in anesthetized dogs thought to be due to its inhibitory effect on the renin-angiotensin system.

General pharmacological properties of the new angiotensin II receptor antagonist (+/-)-1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-1H-benzimidazole-7-carboxylate. Part I: Effects on central nervous system and other properties

The effects of TCV-116 ((+/-)-1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl) biphenyl-4-yl]methyl]-1H-benzimidazole-7-carboxylate, CAS 145040-37-5), a nonpeptide angiotensin II receptor antagonist, on the central nervous and autonomic nervous systems, isolated smooth muscle and digestive system were investigated in various experimental animals. TCV-116 at 1000 mg/kg (p.o.) produced a slight decrease in body tone in mice, but at 300 mg/kg did not affect spontaneous locomotor activity, skeletal muscle coordination, tonic extensor convulsions, pentobarbital-induced sleeping time, frequency of acetic acid-induced writhing, or body temperature in mice or rats. TCV-116 (at 300 mg/kg p.o.) did not affect the spontaneous EEG in conscious, unrestrained cats, or (at 100 mg/kg i.d.) the spinal reflex in anesthetized cats. CV-11974, the active metabolite of TCV-116, did not inhibit neuromuscular transmission in isolated rat phrenic nerve-diaphragm preparations (10(-5) mol/l and 10(-4) mol/l). In anesthetized cats, TCV-116 at 100 and 300 mg/kg (i.d.) slightly reduced the pressor response to carotid occlusion, but had no effect on the bradycardic response to stimulation of the cervical vagus nerve, contraction of the nictitating membrane induced by electrical stimulation of the cervical sympathetic preganglionic nerve, or the changes in blood pressure in response to acetylcholine, histamine, norepinephrine, or bradykinin. CV-11974 had no effect on agonist-induced contraction of guinea pig ileum. In isolated smooth muscle preparations, CV-11974 even at 10(-4) mol/l did not affect the spontaneous motility of the rabbit ileum or the rat uterus, or KCl-induced tension in guinea pig trachea. TCV-116 at 300 mg/kg (p.o.) had no significant effect on gastric emptying or intestinal transport of a semisolid meal in rats, or on gastric secretion in pylorus-ligated rats. TCV-116 (30-300 mg/kg p.o.) had no effect on carrageenin-induced paw edema in rats. The results suggest that TCV-116 exerts no notable pharmacological effects on the central nervous system, autonomic nervous system, gastrointestinal function or smooth muscle function.

A case of bronchial cast

We report a case of bronchial cast in a boy 1 year and 5 months old. Bronchial casts often obstruct the main bronchi, causing dyspnea and hypoxia. The bronchial cast was studied pathologically, with findings of eosinophilia and neutrophilic infiltration; the cast seemed to involve an allergic reaction. Such casts can be removed during bronchoscopy, but we used aspiration.

Reduction of serum cholesterol levels alters lesional composition of atherosclerotic plaques. Effect of pravastatin sodium on atherosclerosis in mature WHHL rabbits

We examined whether serum cholesterol reduction alters the lesional composition of atherosclerotic plaques. To reduce serum cholesterol levels, we gave pravastatin sodium, a 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitor, to mature Watanabe heritable hyperlipidemic rabbits, an LDL receptor-deficient animal model, for 48 weeks. Atherosclerotic lesions were immunohistochemically and conventionally stained and each lesional component area was measured by a color image analyzer. Compared with those of a placebo group, serum LDL cholesterol levels were reduced by 22% (P<.05). Data for atherosclerosis indicated a significant decrease in percent of surface lesion area (26% reduction) and in intimal thickening (30% reduction) in the abdominal aorta, as well as in coronary stenosis (29% reduction). Data for lesional composition indicated a significant decrease in the percent area of macrophage plus extracellular lipid deposits in aortic lesions (32% reduction) and coronary lesions (45% reduction). A significant increase was observed in the percent area of collagen in aortic lesions and in the percent area of smooth muscle cells in coronary lesions. The plaques seemed to become stable lesions as a result of pravastatin treatment. In conclusion, a long-term reduction of serum LDL cholesterol reduced lipid-related lesional components, in addition to suppressing the progression of established atherosclerosis.

High dose of fluvastatin sodium (XU62-320), a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, lowers plasma cholesterol levels in homozygous Watanabe-heritable hyperlipidemic rabbits

The effects of fluvastatin sodium (XU62-320), a new type of inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on plasma cholesterol and triacylglycerol levels were investigated using homozygous Watanabe-heritable hyperlipidemic (WHHL) rabbit, an LDL-receptor-deficient animal which expresses a hepatic LDL receptor activity less than 5% that of control rabbits. Plasma levels of total, VLDL- and LDL-cholesterol were decreased profoundly after oral administration of fluvastatin at a dose of 50 mg/kg per day for 4 weeks. Plasma triacylglycerol levels were not affected by fluvastatin. Hepatic HMG-CoA reductase activity increased by 3-fold and hepatic LDL receptor activity increased by only 3.7-fold, as calculated by Scatchard plot analysis, with fluvastatin administration for 4 weeks, and the hepatic mRNA level for the rabbit LDL receptor was increased by 3-fold. Combined administration of fluvastatin (50 mg/kg per day) and cholestyramine, a bile acid sequestrant resin, at a level of 2% of the diet for 4 weeks more profoundly decreased plasma total, VLDL- and LDL-cholesterol levels with induction of hepatic cholesterol 7 alpha-hydroxylase and no further induction of the hepatic LDL receptor. Plasma triacylglycerol levels were increased by the combination treatment. These results suggest that high dose of fluvastatin sodium is effective in lowering plasma cholesterol levels in homozygous WHHL rabbits through the shared mechanisms involving decrease in production and secretion of cholesterol from the liver and the induction of hepatic LDL receptor. Additional effect of cholestyramine on decrease in plasma cholesterol levels seems to be due to the further decrease in hepatic cholesterol secretion by up-regulation of hepatic cholesterol 7 alpha-hydroxylase.

Effects of the non-peptide angiotensin II receptor antagonist TCV-116 on systemic and renal hemodynamics in dogs with renal hypertension

The effects of TCV-116, a new non-peptide angiotensin II receptor antagonist, on systemic and renal hemodynamics were studied in conscious normotensive and renal hypertensive (2-kidney, 1-clip Gold-blatt type) dogs. When orally administered at 0.03 to 1.0 mg/kg, TCV-116 inhibited the pressor response to angiotensin II in conscious normotensive dogs in a dose-dependent fashion. The IC50 and IC100 values were 0.06 mg/kg and 0.86 mg/kg, respectively. TCV-116 at doses of 0.3 mg/kg and 1.0 mg/kg dose-dependently and persistently decreased systolic and diastolic blood pressure in both dogs with acute renal (hyperreninemic) and those with chronic renal (normoreninemic) hypertension. Even a high dose of TCV-116 (10 mg/kg, p.o.) increased effective renal plasma flow without affecting blood pressure or glomerular filtration rate in normotensive dogs. Furthermore, even at this high dose, TCV-116 did not reduce effective renal plasma flow or glomerular filtration rate in dogs with renal hypertension despite marked reduction in systemic blood pressure. The angiotensin converting enzyme inhibitor enalapril (10 mg/kg, p.o.) had renal hemodynamic effects similar to those of TCV-116. These findings indicate that TCV-116 has potent hypotensive effects not only in dogs with acute renal hypertension but also in those with chronic renal hypertension, but does not appear to adversely affect renal hemodynamics.

Effect of fluvastatin sodium on secretion of very low density lipoprotein and serum cholesterol levels. In vivo study using low density lipoprotein receptor deficient watanabe heritable hyperlipidemic rabbits

The hypolipidemic effects of fluvastatin sodium (XU 62-320, CAS 93957-55-2), a new 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, were examined. Fluvastatin sodium was administered to Watanabe heritable hyperlipidemic (WHHL) rabbits, a low density lipoprotein (LDL) receptor deficient animal model, for 6 weeks at doses of 12.5 mg/kg, 25 mg/kg, and 50 mg/kg. Total cholesterol levels in serum, in very low density lipoproteins (VLDL), in intermediate density lipoprotein, and in LDL decreased dose-dependently. In the 50 mg/kg group, cholesterol reduction in each of the aforementioned segments was 50%, 91%, 94% and 33%, respectively. The secretion rate of VLDL-cholesterol, as determined by intravenous injection of Triton WR-1339, also decreased in a dose-dependent manner, showing a reduction of 16% (p < 0.05) in the 50 mg/kg group. In addition, the cholesterol content of newly-secreted VLDL also decreased dose-dependently. These results indicate that fluvastatin sodium has a potent hypolipidemic effect, and suggest that one of the mechanisms responsible for the reduction of serum cholesterol may be the suppression of VLDL-cholesterol secretion.

Potent cholesterol-lowering effect by human granulocyte-macrophage colony-stimulating factor in rabbits. Possible implications of enhancement of macrophage functions and an increase in mRNA for VLDL receptor

The mechanism by which granulocyte-macrophage colony-stimulating factor (GM-CSF) lowers plasma cholesterol levels is not well understood. We tested recombinant human GM-CSF (rhGM-CSF) on plasma cholesterol and triglycerides in rabbits and attempted to determine the mechanisms of the cholesterol-lowering effect. rhGM-CSF (20 micrograms.kg-1.d-1) was administered to normal and cholesterol-fed rabbits for 2 weeks and to Watanabe heritable hyperlipidemic (WHHL) rabbits for 1 week. The administration of rhGM-CSF markedly lowered cholesterol and triglycerides, an effect that persisted in normal and cholesterol-fed rabbits even after termination of treatment. The cholesterol-lowering effect of rhGM-CSF was also observed in WHHL rabbits. rhGM-CSF was capable of stimulating granulocyte-macrophage colony formation in vitro in rabbits with an effect comparable to that in humans. Northern blot analysis with rabbit very-low-density-lipoprotein (VLDL) receptor cDNA revealed that rhGM-CSF increased the levels of VLDL receptor mRNA in muscle of rabbits after only 1.5 hours of treatment compared with control (2.6-fold), with the 1.5-fold increase following a 5-day administration. No changes in the levels of LDL receptor mRNA in liver, spleen, and bone marrow were observed in the treated rabbits. These findings suggest that the cholesterol-lowering effect of rhGM-CSF may be mediated by enhancement of macrophage functions in lipid metabolism and the increase in mRNA for VLDL receptor in rabbits.

Involvement of LDL receptor in the proliferation of vascular smooth muscle cells

To study the involvement of the low-density lipoprotein (LDL) receptor in the growth of vascular smooth muscle cells (VSMC), we compared the proliferation of cultured VSMC from Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack the LDL receptor, and VSMC from normal Japanese white rabbits in response to platelet derived growth factor (PDGF). The increase in the number of VSMC from WHHL rabbits in response to PDGF (10(-8) M) was significantly lower than that of VSMC from normal rabbits. PDGF stimulated the synthesis of DNA in VSMC from both normal rabbits and WHHL rabbits, but the response was significantly lower in the latter. To determine the involvement of the LDL receptor in the decreased mitogenic response of WHHL rabbit VSMC, we used an anti-LDL receptor monoclonal antibody (MAb) to normal rabbit VSMC; DNA synthesis of VSMC was stimulated by PDGF, but the effect was significantly blocked by the anti-LDL receptor MAb. Mitogen-activated protein (MAP) kinase activity in normal rabbit VSMC was increased by exposure to PDGF, but the effect was significantly suppressed in the presence of the MAb. The anti-LDL receptor MAb markedly inhibited LDL binding to the surface of normal rabbit VSMC. These results suggest that the LDL receptor influences the proliferation of VSMC and thus might be involved in the pathogenesis of atherosclerosis.

Relation of N-glycosylation of apolipoprotein B-100 to cellular metabolism of low density lipoprotein

We studied the functional role of N-linked sugar chains of apolipoprotein (apo) B-100 of low density lipoprotein (LDL) in cholesterol metabolism. The N-linked sugar chains of apo B-100 of LDL obtained from four homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits were liberated by hydrazinolysis, followed by NaB3H4 reduction and were fractionated by paper electrophoresis and column chromatography. They consisted of one neutral (N) and two acidic (A1, A2) fractions. The ratio of apo B-100 acidic fractions (A1+A2) varied among 4 WHHL rabbits. Serial measurements of serum cholesterol levels showed that they decreased with aging in each of 4 WHHL rabbits. We investigated the relation of the ratio of acidic sugar chains of apo B-100 to the serum cholesterol levels. Reciprocals of the serum cholesterol levels were significantly correlated with the ratio of acidic sugar chains of apo B-100 (r = 0.901, P < 0.001). To elucidate the role of N-linked sugar chains of apo B-100, we investigated cellular uptake of LDL in normal rabbit skin fibroblasts. The amounts of association, degradation and cholesteryl esterification of LDL with a lower ratio of acidic sugar chains at 37 degrees C were greater than those of LDL with a higher ratio of acidic sugar chains. These results suggest that N-glycosylation of apo B-100 may be related with serum cholesterol levels and N-linked sugar chains of apo B-100 may play an important role in cellular metabolism of LDL.

Cell compositions of coronary and aortic atherosclerotic lesions in WHHL rabbits differ. An immunohistochemical study

This study investigated whether coronary atherosclerosis was different from aortic atherosclerosis in Watanabe heritable hyperlipidemic rabbits. Atherosclerotic lesions were immunohistochemically stained by using a monoclonal antibody for rabbit macrophages (RAM-11) and a monoclonal antibody for muscle actin (HHF35) and were also subjected to conventional staining. The areas of the major lesional components, ie, macrophages, smooth muscle cells, collagen fibers, and extracellular lipid deposits, were measured with a color image analyzer. The percent macrophage area in coronary lesions was significantly lower compared with aortic lesions at all stages (early fatty streak, transitional, and advanced), while the percent smooth muscle cell area and collagen area were significantly higher in early fatty streak lesions of the coronary arteries. In addition, the macrophage area/smooth muscle cell area ratio was significantly lower in coronary lesions compared with aortic lesions at all stages. In conclusion, coronary atherosclerosis had a small number of macrophages and was rich in smooth muscle cells, whereas aortic atherosclerosis showed the opposite features. These results suggested that the role of macrophages and smooth muscle cells in the initiation and/or progression of coronary atherosclerosis differs from the role of these cells in aortic atherosclerosis.

Pravastatin sodium, a competitive inhibitor of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase, decreases the cholesterol content of newly secreted very-low-density lipoprotein in Watanabe heritable hyperlipidemic rabbits

We examined the secretion of very-low-density lipoprotein (VLDL) when hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, a rate-limiting enzyme of cholesterol biosynthesis, was inhibited. To inhibit HMG-CoA reductase in liver, pravastatin sodium, a competitive inhibitor of HMG-CoA reductase, was administered to homozygous Watanabe heritable hyperlipidemic (WHHL) rabbits, a low-density lipoprotein receptor-deficient animal model, at a dosage of 50 mg/kg per day for 5 weeks. Although triglyceride levels were not changed, total cholesterol levels of sera and each atherogenic lipoprotein were decreased by approximately 30%. As a result, the percentage of cholesterol concentration in newly secreted VLDL was significantly decreased by 24%. The VLDL secretion rate was determined by intravenous injection of Triton WR-1339. The VLDL secretion rate was significantly decreased by 23% using cholesterol as an index, but it did not change using triglyceride, phospholipid, or protein as an index. It is concluded that one of the mechanisms of serum total cholesterol decrease due to reduction of the putative cholesterol pool of the liver in homozygous WHHL rabbits is caused by a decrease of cholesterol content in newly secreted VLDL particles.

Quantitative characterization of insulin-glucose response in Watanabe heritable hyperlipidemic and cholesterol-fed rabbits and the effect of cilazapril

A great deal of evidence suggests that insulin resistance, via hyperinsulinemia, contributes to hyperlipoproteinemia and coronary atherosclerosis. When Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model of familial hypercholesterolemia (FH), are compared with normolipidemic Japanese White (JW) rabbits, an elevated fasting plasma insulin level and a heightened plasma insulin response to an intravenous (i.v.) glucose challenge are found. To elucidate the mechanism behind this phenomenon, a two-compartment model of the glucose/insulin system was fitted to empirical time courses of glucose and insulin concentrations during an i.v. glucose tolerance test (IVGTT) by nonlinear least-square regression, and the model parameters such as the glucose utilization rate constant, insulin degradation rate constant, and pancreas sensitivity were determined. WHHL rabbits showed decreased values of glucose utilization and insulin degradation rate constants and slightly higher values of pancreas sensitivity. This suggests that insulin resistance occurs in extrapancreatic tissues, and that this may be attributable to insulin receptor and/or post-insulin receptor abnormalities. Cholesterol feeding did not significantly change glucose tolerance or insulin action in JW rabbits. The effects of an angiotensin-converting enzyme (ACE) inhibitor, cilazapril, on insulin resistance were also examined in WHHL and JW rabbits. A decreased insulin response to an i.v. glucose challenge and increased glucose utilization and insulin degradation rate constants were observed in WHHL rabbits that had been treated with cilazapril, indicating that cilazapril improved insulin resistance in WHHL rabbits, possibly by increasing the number of insulin receptors. No significant differences were found in glucose tolerance and insulin action in JW rabbits before and after cilazapril administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Dextran sulfate, a competitive inhibitor for scavenger receptor, prevents the progression of atherosclerosis in Watanabe heritable hyperlipidemic rabbits

Dextran sulfate competes with binding of modified LDL to the scavenger receptor in macrophages. To elucidate the role of dextran sulfate in the atherosclerotic process, 100 mg of dextran sulfate in drinking water was given to 5 Watanabe heritable hyperlipidemic (WHHL) rabbits for 12 months starting at age 4 months. During the experimental period, there were no significant differences in plasma cholesterol levels between dextran sulfate-treated and untreated rabbits. After 12 months' treatment, accumulation of cholesterol ester in total aorta was significantly suppressed in dextran sulfate-treated rabbits as compared with untreated rabbits (71.4 +/- 22.3 vs. 42.7 +/- 16.5 mg/g dry weight, P < 0.05). Furthermore, lesion area with atherosclerotic plaques in treated rabbits was significantly less than that in untreated rabbits (59.7 +/- 24.5 vs. 30.4 +/- 14.4%, P < 0.05). These results indicate that dextran sulfate might prevent the progression of atherosclerosis by competitively inhibiting the binding of modified LDL to scavenger receptors.