Efficacy and safety of ketamine for pediatric and adolescent super-refractory status epilepticus and the effect of cerebral inflammatory conditions

OBJECTIVE

To investigate the short-term benefits and adverse effects of ketamine in the treatment of pediatric and adolescent super-refractory status epilepticus (SRSE), with a focus on the inflammatory etiology.

METHODS

This retrospective observational cohort study included a consecutive series of 18 pediatric to adolescent patients with SRSE admitted between 2008 and 2023 and treated with ketamine. Seizure frequency per hour before and after ketamine administration and response rate were calculated. Neurological decline, catecholamine administration, and adverse effects were also assessed. The patients were divided into inflammatory and non-inflammatory etiology groups.

RESULTS

The median age at SRSE onset was 1 year 5 months (range: 11 days-24 years), and 78% of the patients were male individuals. The median duration of treatment was 7.5 days (interquartile range: 2.8-15.5 days). Fifteen (83%) patients achieved >50% seizure reduction. The median seizure frequency before and after ketamine treatment was 5.9 and 0.9, respectively, showing a significant reduction in seizure frequency (p < 0.0001). Ten patients had inflammatory etiologies including bacterial meningitis (n = 2), viral encephalitis (n = 3), and febrile infection related epilepsy syndrome (n = 5). The inflammatory etiology group required a longer treatment duration (p = 0.0453) and showed lower seizure reduction (p = 0.0264), lower response rate (p = 0.0044), and higher neurological decline (p = 0.0003) than the non-inflammatory etiology group. Three (17%) patients experienced transient adverse events requiring intervention within 24 h of initiating ketamine administration.

CONCLUSIONS

Ketamine administration was associated with fewer serious adverse events and a reduced seizure frequency. Additionally, inflammatory conditions may weaken the efficacy of ketamine in patients with SRSE.

Arterial stiffness of the aorta and iliofemoral artery and their responses to nitroglycerin administration in myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits

OBJECTIVES

The role of hypercholesterolemia in arterial stiffness, which usually reflects the progression of atherosclerosis has not been fully investigated. To clarify the meaning of arterial stiffness in hypercholesterolemia, we evaluated arterial stiffness in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits by using new arterial stiffness indices of the aorta and common iliac to femoral artery. The new arterial stiffness indices of both arteries were determined by the application of the theory of cardio-ankle vascular index (CAVI) to the aorta (aBeta) and ilio-femoral artery (ifBeta). Furthermore, the responses of both indices to nitroglycerin (NTG) administration were compared between WHHHMI and normal rabbits.

DESIGN AND METHODS

aBeta and ifBeta of WHHLMI and normal rabbits were measured under anesthesia. Pulse wave velocity in the whole aorta (aPWV) and ilio-femoral artery (ifPWV), blood pressure, and other parameters were measured before and after administration of NTG (50-120 μg/kg/min) every 1 for 5 min.

RESULTS

Atherosclerotic lesions were observed in the aorta, but a little in the ilio-femoral artery in WHHLMI rabbits. Compared with normal rabbits, aBeta was significantly higher, but ifBeta was lower in WHHLMI rabbits. When NTG was administered, ifBeta decreased significantly in both groups; however, aBeta increased in normal rabbits, but remained unchanged in WHHIMI rabbits.

CONCLUSION

These findings suggested that hereditary hypercholesterolemia in rabbits did not uniformly enhance arterial stiffness in elastic artery and muscular artery. The responses to NTG were also different between two arteries. The mechanism of these different responses needs further studies.

Longitudinal electroencephalogram findings predict acute neurological and epilepsy outcomes in patients with hemorrhagic shock and encephalopathy syndrome

OBJECTIVE

Hemorrhagic shock and encephalopathy syndrome (HSES) is a severe subtype of acute encephalopathy with a poor prognosis. The association between electroencephalogram (EEG) findings and neurological outcomes in patients with HSES, including the onset of epilepsy, remains unclear.

METHODS

Thirty-two children with HSES registered in a database of Osaka City General Hospital between 2003 and 2018 were included in this study. The EEG findings which consisted of continuity, reactivity, state change, voltage, rhythmic and periodic patterns, and electrographic or electroclinical seizures, in the onset phase were evaluated for patient outcome. Patients who avoided acute death were investigated for epilepsy by a longitudinal EEG. Seizure types were determined by ictal video recordings.

RESULTS

We analyzed EEG findings in the onset phase of 30 patients. Severely to extremely abnormal EEG pattern (deteriorated continuity more than discontinuous pattern, presence of generalized abnormal low voltage slow wave, and presence of generalized rhythmic and periodic patterns) in the onset phase correlated with poor outcome (p = 0.0024). Subsequently, 9/23 patients (39%) developed epilepsy, of which a total of eight had epileptic spasms. A significant correlation between interictal epileptic discharges and the development of epilepsy was observed as early as within three months (p = 0.0003).

CONCLUSIONS

EEG pattern in the onset phase may be useful to predict the neurological prognosis in the acute stage. Moreover, this study demonstrated that longitudinal EEG findings after the acute phase of HSES were significantly related to the development of epilepsy. EEG findings are useful for predicting acute prognosis and epilepsy in patients with HSES.

Pathological Investigations of Intracranial Atherosclerosis Using Multiple Hypercholesterolemic Rabbit Models

BACKGROUND

Intracranial atherosclerosis (ICAS) is one of the most common causes of ischemic stroke, but there are few animal models that can recapitulate its pathological features. In this study, we examined ICAS pathological features and anatomic distributions using three types of hyperlipidemic rabbit models. We also investigated the effect of different lipoprotein profiles and hypertension on ICAS.

MATERIALS AND METHODS

We examined Watanabe heritable hyperlipidemic (WHHL) rabbits, apoE knockout (KO) rabbits and wild-type rabbits (WT) fed a cholesterol diet, in addition to WT rabbits fed a standard diet as a control. The whole brain was dissected and embedded in paraffin. Serial sections were stained with either hematoxylin/eosin or elastica van Gieson, or immunohistochemically stained with monoclonal antibodies against macrophages and smooth muscle cells. We investigated (1) the presence of cerebral atherosclerosis; (2) the lesion locations in the cerebral arteries; (3) the degree of lumen stenosis; (4) pathological features and cellular components of the lesions in these rabbits; and (5) whether hypertension affects ICAS.

RESULTS

ICAS was detected in apoE and WHHL rabbits, but not in WT rabbits. Compared with apoE KO rabbits, WHHL rabbits had greater ICAS. The lesions of cerebral atherosclerosis were mainly distributed at the bifurcations of the posterior cerebral artery, basilar artery and vertebral artery, and they were basically characterized by smooth muscle cells and extracellular matrix with few macrophages. The extent of the ICAS in WHHL rabbits was significantly increased by hypertension.

CONCLUSIONS

ICAS was detected in WHHL and apoE KO rabbits, and occurred in specific locations in the cerebral arteries. Hypertension promotes the development of ICAS in the setting of hypercholesterolemia.

Intrathecal dexamethasone therapy for febrile infection-related epilepsy syndrome

OBJECTIVE

Increasing reports suggest a role for immunological mechanisms in febrile infection-related epilepsy syndrome (FIRES). The objective of this study was to elucidate the efficacy and safety of intrathecal dexamethasone therapy (IT-DEX).

METHODS

We assessed six pediatric patients with FIRES who were administered add-on IT-DEX in the acute (n = 5) and chronic (n = 1) phases. We evaluated clinical courses and prognosis. We measured cytokines/chemokines in cerebrospinal fluid (CSF) from FIRES patients at several points, including pre- and post-IT-DEX, and compared them with control patients with chronic epilepsy (n = 12, for cytokines/chemokines) or with noninflammatory neurological disease (NIND, n = 13, for neopterin).

RESULTS

Anesthesia was weaned after a median of 5.5 days from IT-DEX initiation (n = 6). There was a positive correlation between the duration from the disease onset to the introduction of IT-DEX and the length of ICU stay and the duration of mechanical ventilation. No patient experienced severe adverse events. Seizure spreading and background activities on electroencephalography were improved after IT-DEX in all patients. The levels of CXCL10, CXCL9, IFN-γ, and neopterin at pre-IT-DEX were significantly elevated compared to levels in epilepsy controls, and CXCL10 and neopterin were significantly decreased post-IT-DEX, but were still higher compared to patients with chronic epilepsy. IL-6, IL-8, and IL-1β were significantly elevated before IT-DEX compared to epilepsy controls, though there was no significant decrease post-treatment.

INTERPRETATION

IT-DEX represents a therapeutic option for patients with FIRES that could shorten the duration of the critical stage of the disease. The effect of IT-DEX on FIRES might include cytokine-independent mechanisms.

Effect of the dipeptidyl peptidase-4 inhibitor linagliptin on atherosclerotic lesions in Watanabe heritable hyperlipidemic rabbits: iMap-IVUS and pathological analysis

Dipeptidyl peptidase-4 (DPP-4) inhibitors have potential as a treatment for atherosclerosis. However, it is unclear whether DPP-4 inhibitors stabilize atherosclerotic plaque or alter the composition of complex plaque. Sixteen Watanabe heritable hyperlipidemic rabbits aged 10-12 weeks with atherosclerotic plaque in the brachiocephalic artery detected by iMap^™ intravascular ultrasound (IVUS) were divided into a DPP-4 inhibitor group and a control group. Linagliptin was administered to the DPP-4 inhibitor group via nasogastric tube at a dose of 10 mg/kg/day for 16 weeks, and control rabbits received the same volume of 0.5% hydroxyethylcellulose. After evaluation by IVUS at 16 weeks, the brachiocephalic arteries were harvested for pathological examination. IVUS revealed that linagliptin significantly reduced the plaque volume and vessel volume (control group vs. DPP-4 inhibitor group: ∆plaque volume, 1.02 ± 0.96 mm³ vs.  - 3.59 ± 0.92 mm³, P = 0.004; ∆vessel volume,  - 1.22 ± 2.36 mm³ vs.  - 8.66 ± 2.33 mm³, P = 0.04; %change in plaque volume, 6.90 ± 5.62% vs.  - 15.06 ± 3.29%, P = 0.005). With regard to plaque composition, linagliptin significantly reduced the volume of fibrotic, lipidic, and necrotic plaque (control group vs. DPP-4 inhibitor group: ∆fibrotic volume, 0.56 ± 1.27 mm³ vs.  - 5.57 ± 1.46 mm³, P = 0.04; ∆lipidic volume, 0.24 ± 0.24 mm³ vs.  - 0.42 ± 0.16 mm³ P = 0.04; ∆necrotic volume, 0.76 ± 0.54 mm³ vs.  - 0.84 ± 0.25 mm³, P = 0.02). Pathological examination did not show any significant differences in the %smooth muscle cell area or %fibrotic area, but infiltration of macrophages into plaque was reduced by linagliptin treatment (%macrophage area: 12.03% ± 1.51% vs. 7.21 ± 1.65%, P < 0.05). These findings indicate that linagliptin inhibited plaque growth and stabilized plaque in Watanabe heritable hyperlipidemic rabbits.

Integral role of receptor for advanced glycation end products (RAGE) in nondiabetic atherosclerosis

An advanced glycation end products (AGE)/a receptor for AGE (RAGE) axis plays a central role in the pathogenesis of diabetic vascular remodeling. This study was conducted to clarify the role of RAGE in nondiabetic atherosclerosis. We used the aortic and coronary atherosclerotic lesions of Watanabe heritable hyperlipidemic (WHHL) rabbits prone to myocardial infarction (WHHLMI) at 1 to 14 months. Immunohistochemistry demonstrated the significant expression of RAGE as early as at 1 month with the stronger expression at 3 and 7 months, which was remarkably diminished at 14 months. RAGE expression was concordant with AGE accumulation. The major original sources of RAGE expression were macrophages and smooth muscle cells in addition to endothelial cells, and RAGE expression was distributed in the areas of phospholipid products, a component of oxidized LDL and nitrotyrosine. The concentrations of serum AGE did not alter significantly with aging. These findings suggested the expression of RAGE was induced by hyperlipidemia and oxidative stress independent of diabetes in WHHLMI rabbits. Additionally, our in vitro study showed that silencing of RAGE tended to attenuate oxidized-LDL-triggered PAI-1 expression in human cultured macrophages, as well as oxidized-LDL-induced tissue factor expression in peritoneal macrophages, suggesting a possible role of RAGE in prothrombogenic molecular regulation. In conclusion, the present study provides in vivo evidence that RAGE plays an integral role in the initiation and progression of nondiabetic atherosclerosis, suggesting that RAGE may be a novel target for treating not only diabetic but also nondiabetic vascular complications.

Lipid Profiling of Serum and Lipoprotein Fractions in Response to Pitavastatin Using an Animal Model of Familial Hypercholesterolemia

Statins are widely used for the treatment of atherosclerotic cardiovascular diseases. They inhibit cholesterol biosynthesis in the liver and cause pleiotropic effects, including anti-inflammatory and antioxidant effects. To develop novel therapeutic drugs, the effect of blood-borne lipid molecules on the pleiotropic effects of statins must be elucidated. Myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits, an animal model for hypercholesterolemia, are suitable for the determination of lipid molecules in the blood in response to statins because their lipoprotein metabolism is similar to that of humans. Herein, lipid molecules were investigated by lipidome analysis in response to pitavastatin using WHHLMI rabbits. Various lipid molecules in the blood were measured using a supercritical fluid chromatography triple quadrupole mass spectrometry. Cholesterol and cholesterol ester blood concentrations decreased by reducing the secretion of very low density lipoproteins from the liver. Independent of the inhibition effects of cholesterol biosynthesis, the concentrations of some lipids with anti-inflammation and antioxidant effects (phospholipid molecules with n-6 fatty acid side chains, lysophosphatidylcholines, phosphatidylethanolamine plasmalogens, and ceramide molecules) were significantly altered. These findings may lead to further investigation of the mechanism of statin action.

The History of the WHHL Rabbit, an Animal Model of Familial Hypercholesterolemia (I) - Contribution to the Elucidation of the Pathophysiology of Human Hypercholesterolemia and Coronary Heart Disease

Animal models that closely resemble both human disease findings and their onset mechanism have contributed to the advancement of biomedical science. The Watanabe heritable hyperlipidemic (WHHL) rabbit and its advanced strains (the coronary atherosclerosis-prone and the myocardial infarction-prone WHHL rabbits) developed at Kobe University (Kobe, Japan), an animal model of human familial hypercholesterolemia, have greatly contributed to the elucidation of the pathophysiology of human lipoprotein metabolism, hypercholesterolemia, atherosclerosis, and coronary heart disease, as described below. 1) The main part of human lipoprotein metabolism has been elucidated, and the low-density lipoprotein (LDL) receptor pathway hypothesis derived from studies using fibroblasts was proven in vivo. 2) Oxidized LDL accumulates in the arterial wall, monocyte adhesion molecules are expressed on arterial endothelial cells, and monocyte-derived macrophages infiltrate the arterial intima, resulting in the formation and progression of atherosclerosis. 3) Coronary lesions differ from aortic lesions in lesion composition. 4) Factors involved in the development of atherosclerosis differ between the coronary arteries and aorta. 5) The rupture of coronary lesions requires secondary mechanical forces, such as spasm, in addition to vulnerable plaques. 6) Specific lipid molecules in the blood have been identified as markers of the progression of coronary lesions. At the end of the breeding of the WHHL rabbit family at Kobe University, this review summarizes the history of the development of the WHHL rabbit family and their contribution to biomedical science.

The History of the WHHL Rabbit, an Animal Model of Familial Hypercholesterolemia (II) - Contribution to the Development and Validation of the Therapeutics for Hypercholesterolemia and Atherosclerosis

A number of effective drugs have been developed through animal experiments, contributing to the health of many patients. In particular, the WHHL rabbit family (WHHL rabbits and its advanced strains (coronary atherosclerosis-prone WHHL-CA rabbits and myocardial infarction-prone WHHLMI rabbits) developed at Kobe University (Kobe, Japan) contributed greatly in the development of cholesterol-lowering agents. The WHHL rabbit family is animal models for human familial hypercholesterolemia, coronary atherosclerosis, and coronary heart disease. At the end of breeding of the WHHL rabbit family, this review summarizes the contribution of the WHHL rabbit family to the development of lipid-lowering agents and anti-atherosclerosis agents. Studies using the WHHL rabbit family demonstrated, for the first time in the world, that lowering serum cholesterol levels or preventing LDL oxidation can suppress the progression and destabilization of coronary lesions. In addition, the WHHL rabbit family contributed to the development of various compounds that exhibit lipid-lowering and anti-atherosclerotic effects and has also been used in studies of gene therapeutics. Furthermore, this review also discusses the causes of the increased discrepancy in drug development between the results of animal experiments and clinical studies, which became a problem in recent years, and addresses the importance of the selection of appropriate animal models used in studies in addition to an appropriate study design.

Distribution of atherosclerotic lesions in various arteries of WHHLMI rabbits, an animal model of familial hypercholesterolemia

In WHHLMI rabbits, arterial lesions develop spontaneously in various arteries even with standard chow. Here, we examined the development of arterial lesions in various arteries to demonstrate standard characteristics of arterial lesions in WHHLMI rabbits. For WHHLMI rabbits at 6, 12, 20, and 30 months of age, lesion areas and areas of arterial lumen surfaces were measured using image analysis software. Histopathological sections of arterial lesions were stained with elastic van Gieson staining. Arterial lesions developed around bifurcations and expanded with aging. In the aorta, atheromatous lesions were severe in the thoracic aorta but were mild in the distal part of the abdominal aorta. Carotid artery lesions progressed in the proximal region and at bifurcations, and the histopathological features were similar to those of coronary lesions. Pulmonary artery lesions contained many foam cells. Fibrous lesions were observed in the proximal and distal areas of the renal arteries, at the bifurcation of the iliac-femoral artery and mesenteric artery, and around the anastomosis of vertebral arteries. Lesions in the celiac artery contained foam cells and/or lipid droplets within fibrous lesions. In a pair of right and left arteries, the arterial lesions tended to progress more in the right artery. Gender did not affect analysis of arterial lesions. In conclusion, the arterial lesions expanded from bifurcations, and the morphological features of the arterial lesions varied depending on the type of artery. These results serve as reference data for arterial lesions in studies using WHHLMI rabbits.

Species differences in lipoprotein lipase and hepatic lipase activities: comparative studies of animal models of lifestyle-related diseases

Lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) have an important role in lifestyle-related diseases. To evaluate species differences, we compared LPL and HTGL activities in different animal models of lifestyle-related diseases using the same assay kit. Normal animals (JW rabbits, ICR mice, and SD rats), a hypercholesterolemic animal model (WHHLMI rabbits), and obese animal models (KK-A^y mice and Zucker fatty rats) fed standard chow were used in this study. Plasma was prepared before and after an intravenous injection of heparin sodium under fasting and feeding. LPL and HTGL activities were measured with the LPL/HTGL activity assay kit (Immuno-Biological Laboratories) using an auto-analyzer. Only in mice, high HTGL activity was observed in pre-heparin plasma. In normal animals, LPL and HTGL activities were high in ICR mice and SD rats but low in JW rabbits. Compared to normal animals, LPL activity was high in Zucker fatty rats and WHHLMI rabbits at both fasting and feeding, while LPL activity after feeding was low in KK-A^y mice. HTGL activity was higher in fasted and fed WHHLMI rabbits and fasted Zucker fatty rats, but was lower in fed KK-A^y mice. Gender difference was observed in HTGL activity in SD rats and LPL activity in WHHLMI rabbits but not in ICR mice. In conclusion, this simple assay method was effective for measuring LPL and HTGL activities of experimental animals, and the activities are highly regulated depending on animal species, animal models, feeding/fasting conditions and genders.

Clasmatodendrosis is associated with dendritic spines and does not represent autophagic astrocyte death in influenza-associated encephalopathy

BACKGROUND

Influenza-associated encephalopathy (IAE) is one of the most serious CNS complications of an influenza virus infection, with unclear pathophysiology. Clasmatodendrosis is a complex of morphological changes in astrocytes characterized by fragmentation of the distal processes and swollen cell bodies. Although pathologists in Japan have long been aware of the presence of clasmatodendrosis in IAE brains, no details of the phenomenon have been published to date. We aimed to confirm the existence, and characterize the spatial distribution of clasmatodendrosis in postmortem IAE brains.

METHODS

Autopsied brains from 7 patients with IAE and 8 non-IAE subjects were examined immunohistochemically. In addition, immunofluorescent staining and electron microscopy were performed.

RESULTS

Clasmatodendrosis was present in all examined regions of the IAE brains, but none of the control brains. Fragmented processes of astrocytes in IAE brains were closely adjacent to synapses on the dendritic spines, with the fragmentation especially prominent in the cerebellar molecular layer. In addition, the clasmatodendrotic astrocytes were negative for autophagy markers. Furthermore, whereas aquaporin 4 was predominantly detected in the perivascular endfeet of astrocytes in the control brains, its primary localization site shifted to the fragmented perisynaptic processes in the IAE brains.

CONCLUSION

Clasmatodendrosis was distributed diffusely in the IAE brains in close association with synapses, and was not caused by astrocyte autophagy. Clasmatodendrosis may be a suggestive pathological feature of IAE.

Hypertension Enhances Advanced Atherosclerosis and Induces Cardiac Death in Watanabe Heritable Hyperlipidemic Rabbits

Hypertension is a major risk factor for the development of atherosclerosis. Cardiovascular risk has been reported to be significantly increased in hyperlipidemic patients with hypertension. However, it is not clear whether hypertension can directly destabilize plaques, thereby enhancing cardiovascular events. To examine whether hypertension enhances the development of atherosclerosis and increases plaque vulnerability, we generated hypertensive Watanabe heritable hyperlipidemic (WHHL) rabbits by surgical removal of one kidney and partial ligation of the other renal artery and compared the nature of aortic and coronary atherosclerosis in hypertensive WHHL rabbits with normotensive WHHL rabbits. All hypertensive WHHL rabbits died from 34 to 56 weeks after surgery, whereas no normotensive WHHL rabbits died. Pathologic examinations revealed that hypertensive WHHL rabbits showed different degrees of myocardial infarction caused by severe coronary stenosis along with myocardial hypertrophy. Furthermore, aortic lesions in hypertensive WHHL rabbits exhibited a higher frequency of intraplaque hemorrhage and vulnerable plaques than those in normotensive WHHL rabbits. These results indicate that hypertension induced by the surgical removal of one kidney and partial ligation of the other renal artery method in WHHL rabbits may not only enhance the development of atherosclerosis but also destabilize the plaques, increasing cardiac death.

Widely-targeted quantitative lipidomics method by supercritical fluid chromatography triple quadrupole mass spectrometry

Lipidomics, the mass spectrometry-based comprehensive analysis of lipids, has attracted attention as an analytical approach to provide novel insight into lipid metabolism and to search for biomarkers. However, an ideal method for both comprehensive and quantitative analysis of lipids has not been fully developed. Here, we have proposed a practical methodology for widely targeted quantitative lipidome analysis using supercritical fluid chromatography fast-scanning triple-quadrupole mass spectrometry (SFC/QqQMS) and theoretically calculated a comprehensive lipid multiple reaction monitoring (MRM) library. Lipid classes can be separated by SFC with a normal-phase diethylamine-bonded silica column with high resolution, high throughput, and good repeatability. Structural isomers of phospholipids can be monitored by mass spectrometric separation with fatty acyl-based MRM transitions. SFC/QqQMS analysis with an internal standard-dilution method offers quantitative information for both lipid class and individual lipid molecular species in the same lipid class. Additionally, data acquired using this method has advantages, including reduction of misidentification and acceleration of data analysis. Using the SFC/QqQMS system, alteration of plasma lipid levels in myocardial infarction-prone rabbits to the supplementation of EPA was first observed. Our developed SFC/QqQMS method represents a potentially useful tool for in-depth studies focused on complex lipid metabolism and biomarker discovery.-Takeda, H., Y. Izumi, M. Takahashi, T. Paxton, S. Tamura, T. Koike, Y. Yu, N. Kato, K. Nagase, M. Shiomi, and T. Bamba.

Comparison of 125I- and 111In-labeled peptide probes for in vivo detection of oxidized low-density lipoprotein in atherosclerotic plaques

OBJECTIVE

Oxidized low-density lipoprotein (OxLDL) plays a pivotal role in atherosclerotic plaque destabilization, which suggests its potential as a nuclear medical imaging target. We previously developed radioiodinated ¹²⁵I-AHP7, a peptide probe carrying a 7-residue sequence from the OxLDL-binding protein Asp-hemolysin, for specific OxLDL imaging. Although ¹²⁵I-AHP7 recognized OxLDL, it had low stability. Thus, to improve stability, we designed radiolabeled 22-residue peptide probes, ¹²⁵I-AHP22 and ¹¹¹In-AHP22, which include the entire AHP7 sequence, and evaluated the stability, activity, and applications of these probes in vitro and in vivo.

METHODS

Probes consisting of a 21-residue peptide derived from the Asp-hemolysin sequence and an N-terminal Cys or aminohexanoic acid for labeling with ¹²⁵I-N-(3-iodophenyl)maleimide or ¹¹¹In diethylene triamine pentaacetic acid were termed ¹²⁵I-AHP22 and ¹¹¹In-AHP22. An in vitro-binding inhibition assay with OxLDL was performed using ¹²⁵I-AHP7 as a radiotracer. Radioactivity accumulation in the atherosclerotic aorta and plasma intact fraction was evaluated 30 min after intravenous administration of probes in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits.

RESULTS

¹²⁵I-AHP22 and ¹¹¹In-AHP22 were synthesized in ~ 360 and 60 min, respectively, with > 98% radiochemical purities after RP-HPLC purification. An in vitro-binding assay revealed similar or greater inhibition of OxLDL binding by both In-AHP22 and I-AHP22 compared to I-AHP7. The fraction of intact ¹²⁵I-AHP22 and ¹¹¹In-AHP22 in plasma was estimated to be approximately tenfold higher than that of ¹²⁵I-AHP7. Both probes were rapidly cleared from the blood. ¹¹¹In-AHP22 had a 2.3-fold higher accumulation in WHHLMI rabbit aortas compared to control rabbits, which was similar to ¹²⁵I-AHP7. However, ¹²⁵I-AHP22 accumulated to similar levels in aortas of WHHLMI and control rabbits due to high nonspecific accumulation in normal aortas that could be due to high lipophilicity.

CONCLUSIONS

¹¹¹In-AHP22, easily prepared within 1 h, showed moderate affinity for OxLDL, high stability in vivo, and high accumulation in atherosclerotic aortas. ¹¹¹In-AHP22 could be a potential lead compound to develop future effective OxLDL imaging probes.

The Coronary Artery Running Pattern is One of the Causes of Individual Differences in the Progression of Coronary Atherosclerosis in WHHLMI Rabbits, an Animal Model for Coronary Atherosclerosis

AIMS

The relationship between the coronary artery running pattern and development of coronary lesions was re-examined herein using WHHLMI rabbits, an animal model of spontaneous coronary atherosclerosis.

METHODS

The coronary artery running pattern was analyzed using an X-ray computed tomography (CT) apparatus after perfusion. Pathological sections were prepared (Victoria blue-HE staining) at 100 µm intervals from the origin of the left circumflex artery (LCX). The severity of coronary lesions was evaluated based on cross-sectional narrowing (lesion area/inner area of the internal elastic lamina).

RESULTS

In the CT analysis, the angle of the main curvature of the LCX negatively correlated with the percentage of sections with lesions and cross-sectional narrowing. The percentage of sections with lesions was significantly higher in acute angle-type LCX than in obtuse angle-type LCX. Cross-sectional narrowing was also significantly greater in acute angle-type LCX than in obtuse angle-type LCX. The percentage of fibrous lesions was high at the proximal region of LCX, whereas that of lipid-rich lesions was high at the curvature. In 24 months age group, the percentage of sections with calcification in acute angle-type LCX was about twice that in obtuse angle-type LCX.

CONCLUSIONS

Individual differences were observed in the angle of the main curvature of the LCX, which affected the occurrence and extension of atherosclerotic lesions.

Distinct genetic clades of enterovirus D68 detected in 2010, 2013, and 2015 in Osaka City, Japan

The first upsurge of enterovirus D68 (EV-D68), a causative agent of acute respiratory infections (ARIs), in Japan was reported in Osaka City in 2010. In this study, which began in 2010, we surveyed EV-D68 in children with ARIs and analyzed sequences of EV-D68 strains detected. Real-time PCR of 19 respiratory viruses or subtypes of viruses, including enterovirus, was performed on 2,215 specimens from ARI patients (<10 years of age) collected between November 2010 and December 2015 in Osaka City, Japan. EV-D68 was identified in 18 enterovirus-positive specimens (n = 4 in 2013, n = 1 in 2014, and n = 13 in 2015) by analysis of viral protein 1 (VP1) or VP4 sequences, followed by a BLAST search for similar sequences. All EV-D68 strains were detected between June and October (summer to autumn), except for one strain detected in 2014. A phylogenetic analysis of available VP1 sequences revealed that the Osaka strains detected in 2010, 2013, and 2015 belonged to distinct clusters (Clades C, A, and B [Subclade B3], respectively). Comparison of the 5' untranslated regions of these viruses showed that Osaka strains in Clades A, B (Subclade B3), and C commonly had deletions at nucleotide positions 681-703 corresponding to the prototype Fermon strain. Clades B and C had deletions from nucleotide positions 713-724. Since the EV-D68 epidemic in 2010, EV-D68 re-emerged in Osaka City, Japan, in 2013 and 2015. Results of this study indicate that distinct clades of EV-D68 contributed to re-emergences of this virus in 2010, 2013, and 2015 in this limited region.

Morphological features of coronary plaques in WHHLMI rabbits (Oryctolagus cuniculus), an animal model for familial hypercholesterolemia

In order to examine their suitability for studies on coronary atherosclerosis, we evaluated the features of coronary atherosclerotic plaques in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits, a spontaneous animal model for coronary atherosclerosis and myocardial infarction. Coronary segments of the hearts of 187 WHHLMI rabbits (10–29 months old) were sectioned serially and stained histopathologically and immunohistologically. Progression of coronary lesions was prominent in rabbits that had died suddenly. The degree of coronary lesions of females was higher than that of males. Various types of atherosclerotic lesions were observed in the coronary arteries, such as plaques with a large lipid core covered by a thin fibrous cap, fatty streaks, early and advanced fibroatheromas, fibrous lesions, and advanced lesions with calcium accumulation and the vasa vasorum. In rabbits that had died suddenly, the frequencies of fibroatheromas or advanced lesions were higher than those of rabbits euthanized. Matrix metalloproteinase (MMP)-positive macrophages were detected in gaps among endothelial cells at the plaque surface, beneath the fibrous cap of thin-capped fibroatheromas, and at the bottom of the intimal plaques in which the tunica media was attenuated. Immunohistological results suggest that MMP-positive macrophages are involved in the initiation, progression, and destabilization of coronary plaques, in addition to vascular remodeling, even in WHHLMI rabbits. In conclusion, coronary lesions in WHHLMI rabbits resemble human atherosclerotic lesions, and thus, the WHHLMI rabbit is a suitable animal model for studies on human coronary plaques.

High susceptibility of atherosclerotic coronary arteries to the onset of vasospasm and angina pectoris-like symptoms due to coronary spasm in WHHLMI rabbits

We examined the relationship between atherosclerosis and the provocation of coronary spasm as well as the influence of coronary spasm on the onset of acute ischemic myocardial disease. Coronary spasm was provoked in anesthetized normal Japanese white (JW) rabbits and myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits, an animal model for coronary atherosclerosis and myocardial infarction, by injecting ergonovine during the infusion of norepinephrine through a marginal ear vein. A decrease in contrast flow in the left circumflex artery was observed on coronary angiograms. Ischemic changes were observed on the electrocardiograms of 29% (2/7) of JW and 79% (27/34, P=0.007) of WHHLMI rabbits. The frequency of coronary spasm was significantly high in rabbits with severe coronary plaques showing diffuse lesions. Left ventricle motility in vasospasm-positive rabbits, which was evaluated with echocardiograms, was decreased by 29% following the ergonovine injection (P<0.001), and every serum ischemic marker markedly increased 4 h after the provocation of vasospasm. These results demonstrate that atherosclerotic coronary arteries are positively related to the provocation of vasospasm, and vasospasm in severe atherosclerotic coronary segments evokes angina pectoris-like findings and/or non-fatal myocardial infarction. WHHLMI rabbits may be a novel animal model for angina pectoris and acute ischemic heart disease.

Angiotensin II Destabilizes Coronary Plaques in Watanabe Heritable Hyperlipidemic Rabbits

OBJECTIVE

Increased plasma concentrations of angiotensin II (Ang II) have been implicated in many cardiovascular diseases, such as atherosclerosis, aortic aneurysms, and myocardial infarction, in humans. However, it is not known whether high levels of plasma Ang II affect coronary plaque stability and subsequent myocardial infarction. This study was designed to examine whether elevated plasma Ang II can directly induce coronary events, such as acute coronary syndrome.

APPROACH AND RESULTS

To examine the above hypothesis, we infused Ang II (100 ng/min per kg [low group] and 200 ng/min per kg [high group]) or saline vehicle via osmotic minipumps into Watanabe heritable hyperlipidemic rabbits, a model of human familial hypercholesterolemia and atherosclerosis. Infusion of Ang II resulted in mortality rates of 50% and 92% in the low- and high-Ang II groups, respectively, whereas there were no deaths in the vehicle group. Pathological analysis revealed that Ang II-infused Watanabe heritable hyperlipidemic rabbits that died showed myocardial infarction. Furthermore, Ang II-infused Watanabe heritable hyperlipidemic rabbits exhibited coronary plaque erosion and rupture that were associated with thrombosis.

CONCLUSIONS

These findings suggest that increased blood levels of Ang II can destabilize coronary plaques and trigger the thrombosis, which possibly induces myocardial infarction. The model described in this study provides a novel means for the study of human acute coronary syndrome.

High-fructose and high-fat diet-induced insulin resistance enhances atherosclerosis in Watanabe heritable hyperlipidemic rabbits

Background

Individuals with insulin resistance and resulting impaired glucose tolerance along with type 2 diabetes showed an increased prevalence of atherosclerosis. Our aim in this study was to address whether diet-induced insulin resistance plays any roles in the development of aortic and coronary atherosclerosis in hyperlipidemic rabbits.

Methods

We fed Watanabe heritable hyperlipidemic (WHHL) rabbits with a high-fructose and high-fat diet (HFFD) with restricted normal calories and compared the lesions of both aortic and coronary atherosclerosis with those of control WHHL rabbits fed a normal chow diet.

Results

HFFD-fed WHHL rabbits showed insulin resistance and impaired glucose tolerance accompanied by elevated plasma lipid levels and accumulation of adipose tissue even though their body weight was unchanged compared to the control rabbits. At 8 weeks, the aortic gross lesion area of HFFD-fed WHHL rabbits was increased by 40 % over the controls and their lesions were characterized by increased number of macrophages and smooth muscle cells. At 16 weeks, the lesions of HFFD-fed WHHL rabbits showed more advanced lesions such as lipid core formation and calcification. In addition, coronary atherosclerosis was significantly increased in HFFD-fed WHHL rabbits.

Conclusions

These results suggest that insulin resistance accelerates lesion formation of atherosclerosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-015-0024-3) contains supplementary material, which is available to authorized users.

Lipidomic analysis of plasma lipoprotein fractions in myocardial infarction-prone rabbits

Lipids play important roles in the body and are transported to various tissues via lipoproteins. It is commonly assumed that alteration of lipid levels in lipoproteins leads to dyslipidemia and serious diseases such as coronary artery disease (CAD). However, lipid compositions in each lipoprotein fraction induced by lipoprotein metabolism are poorly understood. Lipidomics, which involves the comprehensive and quantitative analysis of lipids, is expected to provide valuable information regarding the pathogenic mechanism of CAD. Here, we performed a lipidomic analysis of plasma and its lipoprotein fractions in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits. In total, 172 lipids in plasma obtained from normal and WHHLMI rabbits were quantified with high throughput and accuracy using supercritical fluid chromatography hybrid quadrupole-Orbitrap mass spectrometry (SFC/Q-Orbitrap-MS). Plasma levels of each lipid class (i.e., phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, lysophosphatidylcholine, lysophosphatidylethanolamine, sphingomyelin, ceramide, triacylglycerol, diacylglycerol, and cholesterol ester, except for free fatty acids) in 21-month-old WHHLMI rabbits were significantly higher than those in normal rabbits. High levels of functional lipids, such as alkyl-phosphatidylcholines, phospholipids including ω-6 fatty acids, and plasmalogens, were also observed in WHHLMI rabbit plasma. In addition, high-resolution lipidomic analysis using very low density lipoprotein (VLDL) and low density lipoprotein (LDL) provided information on the specific molecular species of lipids in each lipoprotein fraction. In particular, higher levels of phosphatidylethanolamine plasmalogens were detected in LDL than in VLDL. Our lipidomics approach for plasma lipoprotein fractions will be useful for in-depth studies on the pathogenesis of CAD.

MRI study of atherosclerotic plaque progression using ultrasmall superparamagnetic iron oxide in Watanabe heritable hyperlipidemic rabbits

OBJECTIVE

The purpose of this study was to evaluate plaque progression by using MRI with ultrasmall superparamagnetic iron oxide (USPIO) and by histopathological studies.

METHODS

We divided 12 Watanabe heritable hyperlipidemic (WHHL) rabbits into 4 groups based on their age (3, 9, 14 and 26 months) and injected them intravenously with 0.8 mmol (Fe) kg(-1) of USPIO (size, 32 nm; concentration, 15 mg dl(-1)). On the fifth post-injection day, they were again given an intravenous injection with 40 μmol kg(-1) of the same USPIO, and MR angiography (MRA) was performed. The signal-to-noise ratio (SNR) in regions of interest in the wall of the upper abdominal aorta was calculated on coronal images. Specimens from the same level of the aorta were subjected to iron staining and RAM-11 immunostaining and used for histopathological study. For statistical analysis of the MRA and histopathological findings, we used analysis of variance [Tukey's honest significant difference (HSD) test].

RESULTS

In 9-month-old rabbits, the SNR was significantly lower than in rabbits of the other ages (p < 0.01), and the area of RAM-11 (DAKO Corporation, Glostrup, Denmark) and iron uptake in the aortic wall was significantly larger (RAM-11, p < 0.01; iron, p < 0.05). These areas were the smallest in 3-month-old rabbits.

CONCLUSION

Histopathologically, the number of macrophages was the greatest in 9-month-old rabbits. Our findings indicate that the SNR on MRI scans reflects the number of macrophages in the aortic wall of WHHL rabbits.

ADVANCES IN KNOWLEDGE

USPIO-enhanced MRI visualized the accumulation of macrophages in early atherosclerotic plaques of WHHL rabbits in the course of natural progression.

Clinical and genetic features of acute encephalopathy in children taking theophylline

BACKGROUND

Theophylline has recently been suspected as a risk factor of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), although there has been no systematic study on the relationship between acute encephalopathy in children taking theophylline (AET) and AESD.

METHODS

We recruited 16 Japanese patients (11 male and 5 female, median age of 2 years and 7 months) with AET from 2008 to 2013. We evaluated their clinical features, such as the duration of first seizure, biphasic clinical course and cranial CT/MRI imaging and compared them with those of AESD. We analyzed the polymorphisms or mutations of genes which are associated with AESD.

RESULTS

Clinically, 12 patients had neurological and/or radiological features of AESD. Only one patient died, whereas all 15 surviving patients were left with motor and/or intellectual deficits. Genetically, 14 patients had at least one of the following polymorphisms or mutations associated with AESD: thermolabile variation of the carnitine palmitoyltransferase 2 (CPT2) gene, polymorphism causing high expression of the adenosine receptor A2A (ADORA2A) gene, and heterozygous missense mutation of the voltage gated sodium channel 1A (SCN1A) and 2A (SCN2A) gene.

CONCLUSIONS

Our results demonstrate that AET overlaps with AESD, and that AET is a multifactorial disorder sharing a genetic background with AESD.

Characteristic neuroradiologic features in hemorrhagic shock and encephalopathy syndrome

Hemorrhagic shock and encephalopathy syndrome is a devastating disease, but the pathogenesis remains unclear. The aim of this study was to examine the usefulness of neuroimaging in establishing a diagnosis and elucidating the pathogenesis. We analyzed the neuroradiologic features of 22 patients who fulfilled the Levin criteria. All patients underwent brain computed tomography (CT), and 14 patients underwent brain magnetic resonance imaging (MRI) including diffusion-weighted imaging in 10 patients. Initial CT showed normal findings in 14 of 18 (78%) patients, but subsequently hypodensities appeared in bilateral watershed zones and progressed to whole brain edema. MRI revealed cytotoxic edema, showing hyperintensities in bilateral watershed zones on diffusion-weighted imaging with a low apparent diffusion coefficient. Serial neuroimaging showed characteristic features of a widespread brain ischemic event mainly in watershed zones in hemorrhagic shock and encephalopathy syndrome.

[A clinical study on high-dose erythropoietin therapy for acute encephalopathy or encephalitis]

OBJECTIVE

We performed high-dose erythropoietin therapy (hEPO) for acute encephalopathy or encephalitis (AE), and evaluated its safety and efficacy.

METHODS

We performed hEPO in AE patients with widespread lesions demonstrated by diffusion-weighted imaging, and prospectively investigated changes in hemoglobin levels, adverse events, changes in images, and developmental quotients.

RESULTS

All four patients showed neither an increase in the hemoglobin level nor adverse event possibly related to hEPO. One patient with acute encephalitis showed resolution of the lesion and normal developmental quotient. Two patients who had acute encephalopathy with febrile convulsive status epilepticus showed mild cerebral atrophy in the recovery phase;one had a normal developmental quotient. The patient with acute necrotizing encephalopathy including a brainstem lesion avoided acute-phase death.

CONCLUSION

Two patients showed no sequelae despite images indicating widespread abnormality. hEPO could be performed safely in patients with AE, however further trials are necessary concerning its efficacy.

Bisphenol A exposure enhances atherosclerosis in WHHL rabbits

Bisphenol A (BPA) is an environmental endocrine disrupter. Excess exposure to BPA may increase susceptibility to many metabolic disorders, but it is unclear whether BPA exposure has any adverse effects on the development of atherosclerosis. To determine whether there are such effects, we investigated the response of Watanabe heritable hyperlipidemic (WHHL) rabbits to 400-µg/kg BPA per day, administered orally by gavage, over the course of 12 weeks and compared aortic and coronary atherosclerosis in these rabbits to the vehicle group using histological and morphometric methods. In addition, serum BPA, cytokines levels and plasma lipids as well as pathologic changes in liver, adipose and heart were analyzed. Moreover, we treated human umbilical cord vein endothelial cells (HUVECs) and rabbit aortic smooth muscle cells (SMCs) with different doses of BPA to investigate the underlying molecular mechanisms involved in BPA action(s). BPA treatment did not change the plasma lipids and body weights of the WHHL rabbits; however, the gross atherosclerotic lesion area in the aortic arch was increased by 57% compared to the vehicle group. Histological and immunohistochemical analyses revealed marked increases in advanced lesions (37%) accompanied by smooth muscle cells (60%) but no significant changes in the numbers of macrophages. With regard to coronary atherosclerosis, incidents of coronary stenosis increased by 11% and smooth muscle cells increased by 73% compared to the vehicle group. Furthermore, BPA-treated WHHL rabbits showed increased adipose accumulation and hepatic and myocardial injuries accompanied by up-regulation of endoplasmic reticulum (ER) stress and inflammatory and lipid metabolism markers in livers. Treatment with BPA also induced the expression of ER stress and inflammation related genes in cultured HUVECs. These results demonstrate for the first time that BPA exposure may increase susceptibility to atherosclerosis in WHHL rabbits.

[Clinical evaluation of six patients with anti-NMDAR encephalitis]

OBJECTIVE

We examined the clinical course and the prognosis of patients with anti-NMDAR encephalitis.

METHODS

We retrospectively evaluated the patients who has distinctive clinical features as anti-NMDAR encephalitis based on their medical records.

RESULTS

There were two male and four female patients with anti-NMDAR encephalitis. They were aged between 13 and 16 years. One of the six, 14 years female patient was negative for anti-NMDAR antibody. All four female patients with anti-NMDAR encephalitis had an ovarian tumor. Neurocognitive dysfunction and epilepsy remained in one female patient with right temporal lobe lesion and one male patient with celebellar abnormalities had mild mental impairment. In three patients including two patients who were examined abdominal MRI for the first time after recovery from the encephalitis, overian tumors became apparent during follow-up. In one of other patients, overian tumors had a tendency to increase in size after recovery.

CONCLUSION

Sequellae were seen in two cases that have abnormalities in brain MRI. As to ovarian tumor, it was considered to be necessary to checkup pelvic MRI for at least four years after the onset of encephalitis.

Collagen morphology and texture analysis: from statistics to classification

In this study we present an image analysis methodology capable of quantifying morphological changes in tissue collagen fibril organization caused by pathological conditions. Texture analysis based on first-order statistics (FOS) and second-order statistics such as gray level co-occurrence matrix (GLCM) was explored to extract second-harmonic generation (SHG) image features that are associated with the structural and biochemical changes of tissue collagen networks. Based on these extracted quantitative parameters, multi-group classification of SHG images was performed. With combined FOS and GLCM texture values, we achieved reliable classification of SHG collagen images acquired from atherosclerosis arteries with >90% accuracy, sensitivity and specificity. The proposed methodology can be applied to a wide range of conditions involving collagen re-modeling, such as in skin disorders, different types of fibrosis and muscular-skeletal diseases affecting ligaments and cartilage.

Decreased sialylation of IgA1 O-glycans associated with pneumococcal hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) in children is usually caused by Shiga-like toxin-producing Escherichia coli, but approximately 5% of cases are caused by invasive pneumococcal infection (P-HUS). Reported herein is the case of a 9-month-old HUS patient with pneumococcal meningitis who needed hemodialysis for 12 days. Decreased sialylation was characterized in both transferrin N-glycans and IgA1 O-glycans, analyzed in the acute phase on mass spectrometry, consistent with S. pneumonia-produced sialidases hydrolyzing both α2,3- and α2,6-linked sialic acids. The method will complement the T-antigen activation test and help to understand the molecular pathology related to P-HUS.

Contribution of the WHHL rabbit, an animal model of familial hypercholesterolemia, to elucidation of the anti-atherosclerotic effects of statins

This year marks the 40th year since the discovery of a mutant rabbit showing spontaneous hyperlipidemia, which is the proband of the Watanabe heritable hyperlipidemic (WHHL) rabbit strain, an animal model of familial hypercholesterolemia, and the first statin, a general term for inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase, a rate limiting enzyme in cholesterol biosynthesis. Nowadays, statins are the primary drug of choice for treating cardiovascular disease. Although several reviews have described clinical trials and in vitro studies of statins, the anti-atherosclerotic effects of statins on animal models have not been comprehensively reviewed. This review summarized the contribution of WHHL rabbits to elucidating the anti-atherosclerotic effects of statins in vivo. Studies using WHHL rabbits verified that statins suppress plaque destabilization by reducing unstable components (foam cells derived from macrophages, foam cell debris, and extracellular lipid accumulation), preventing smooth muscle cell reductions, and increasing the collagen content of plaques. In addition, the expression of matrix metalloproteinases and tissue factor are decreased in intimal macrophages by statin treatment. Lipid-lowering effects of statins alter plaque biology by reducing the proliferation and activation of macrophages, a prominent source of the molecules responsible for plaque instability and thrombogenicity. Although statins remain the standard treatment for cardiovascular disease, new therapeutics are eagerly awaited. WHHL rabbits will continue to contribute to the development of therapeutics.

Vasospasm of atherosclerotic coronary arteries precipitates acute ischemic myocardial damage in myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits

OBJECTIVE

This study tested the hypothesis that vasospasm can trigger coronary plaque injury and acute ischemic myocardial damage.

APPROACH AND RESULTS

Myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits received an intravenous bolus of ergonovine maleate (0.45 µmol/kg) during intravenous infusion of norepinephrine (12 nmol/kg per minute) to provoke coronary spasm in vivo. After this treatment, coronary angiography demonstrated vasospasm, and the ECG showed ischemic abnormalities (ST depression/elevation and T-wave inversion) in 77% of animals (23/30). These changes normalized after nitroglycerin injection. In rabbits that demonstrated these ECG findings for >20 minutes, echocardiograms showed left ventricular wall motion abnormality. Serum levels of heart-type fatty acid-binding protein, cardiac troponin-I, and myoglobin increased markedly 4 hours after spasm provocation. In coronary lesions of myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits with provoked coronary spasm, we observed intimal injury in 60.9% in the form of endothelial cell protrusions (39.1%), denudation (30.4%), and macrophage extravasation (56.5%). Plaque disruption with luminal thrombus, however, was only seen in 2 of 23 animals (8.7%), and mural microthrombus was rarely observed (4.3%).

CONCLUSIONS

These observations show that provocation of vasospasm in myocardial infarction-prone strain of the Watanabe heritable hyperlipidemic rabbits associates with subsequent ischemic myocardial damage. Although treatment with spasmogens altered aspects of plaque morphology, for example, endothelial protrusion and macrophage emigration, thrombosis was rare in these animals with chronic atherosclerotic disease.