Biomedical subjects
Publications and source records attributed to Y Kitaura.
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AIMS: Although increased digitalis-like immunoreactive substances have been found in cases of hypertension and heart failure, no information is available about digitalis-like immunoreactive substances in patients with hypertrophic cardiomyopathy. We investigated digitalis-like immunoreactive substances in the plasma and biopsied specimens of patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: In 40 patients with hypertrophic cardiomyopathy (27 with the non-obstructive type and 13 with the obstructive type), the plasma concentration of digitalis-like immunoreactive substances was studied by fluorescence polarization immunoassay. Right ventricular endomyocardial biopsy specimens were analysed immunohistochemically, using a monoclonal antibody against digoxin. An increase in digitalis-like immunoreactive substances of more than 0.2 ng. ml(-1)in plasma was found in six of 27 patients with non-obstructive hypertrophic cardiomyopathy (22.2%) and five of 13 with obstructive hypertrophic cardiomyopathy (38.4%). Under light microscopy, positive staining against the antibody was observed heterogeneously on some cardiocytes. In non-obstructive hypertrophic cardiomyopathy, digitalis-like immunoreactive substances in the plasma correlated with the left atrial dimension and inversely with the cardiac index. In obstructive hypertrophic cardiomyopathy, plasma and myocardial digitalis-like immunoreactive substances were positively correlated; they also correlated with left ventricular end-diastolic pressures. Under electron microscopy, digitalis-like immunoreactive substances were detected at the sarcolemma in the free wall, T-tubules, intercalated discs and Z-bands of cardiocytes. CONCLUSIONS: Increased digitalis-like immunoreactive substances in plasma and cardiocytes, which may have been caused by pressure and/or volume overload, were found in patients with hypertrophic cardiomyopathy. Digitalis-like immunoreactive substances may act on the sarcolemma of cardiocytes and be transported into the cytoplasm.
Integrated backscatter (IB) provides the quantitative assessment of left atrial spontaneous echo contrast (SEC). The IB intensity of the left atrial cavity relative to the left ventricular cavity is related to atrial thrombus in patients with atrial fibrillation (AF) or sinus rhythm. However, little is known about the relation between the quantitative SEC value of the left atrial cavity and variables implying thromboembolism in nonvalvular AF. To examine this relation, we performed transesophageal echo-cardiography with IB analysis in 65 patients with chronic nonvalvular AF. The quantitative SEC value of the left atrial cavity was defined as the difference between atrial IB intensity and ventricular IB intensity (corrected IB intensity). The corrected IB intensity was correlated with the left atrial dimension (r = 0.25, P =.049), the left atrial appendage velocity (r = -0.41, P <.001), and the duration of AF (r = 0.23, P =. 023). The corrected IB intensity was higher in patients who had a history of hypertension (3.2 +/- 2.2 dB versus 2.0 +/- 1.6 dB, P =. 018), SEC (3.9 +/- 1.9 dB versus 1.4 +/- 1.1 dB, P =.002), and left atrial thrombus (4.5 +/- 2.7 dB versus 2.2 +/- 1.7 dB, P <.001) when compared with those who did not have these abnormalities. The corrected IB intensity was significantly lower in patients with significant mitral regurgitation than in those without it (1.1 +/- 1. 2 dB versus 2.7 +/- 2.0 dB, P =.036). When the cutoff value of the corrected IB intensity was set at >/=2.0 dB, the sensitivity for left atrial thrombus was 78% and the specificity was 55%. In patients with chronic nonvalvular AF, the quantitative SEC value of the left atrial cavity depends on the duration of AF as well as the left atrial dimension and appendage velocity. Although IB may be capable of identifying patients with higher risk of cardiogenic embolism, a large-scale prospective study is needed to actually establish this.
The calpain small subunits of sorcin, grancalcin, and ALG-2 constitute a family of the Ca(2+)-binding proteins with five EF-hand-like motifs (penta-EF-hand domain or PEF domain) in their C-terminal regions and hydrophobic domains with variable lengths in their N-terminal regions. Searching the human DNA data base of expressed sequence tags (EST) revealed novel partial sequences similar to, but distinct from, the sequences of the previously known PEF proteins. We isolated a cDNA clone of near full length by 5'- and 3'-RACE (rapid amplification of cDNA end) methods and compared the predicted amino acid sequence (284 residues) of the novel EF-hand protein, named peflin, with those of known PEF proteins. The PEF domain of peflin is most similar to ALG-2 (40.9% identity) among the family, particularly in EF-1 (46.2%) and EF-3 (57.1%) regions. Peflin has a longer N-terminal hydrophobic domain than any other member of the family, and it contains nine nonapeptide (A/PPGGPYGGP) repeats. Western blot analysis demonstrated that peflin (30 kDa) was expressed in various nonadherent and adherent cultured human cell lines, including Jurkat, HL60, HeLa, and HT1080. Peflin may play basic roles in Ca(2+) signaling irrespective of cell types.
Long-chain fatty acids (LCFA) are the major energy substrate for heart and their oxidation is important for achieving maximal cardiac work. However, the mechanism of uptake of LCFA by myocardium has not been clarified. We previously reported that bovine myocardial LCFA transporter has a sequence homology to human CD36. Clinically, total defect of myocardial uptake of radiolabeled long-chain fatty acid analog [123I-BMIPP: Iodine-123 15-(p-iodophenyl)-(R,S)-methylpentadecanoic acid] has been reported in some restricted cases, but the etiology has not been clarified. In the present study, we analyzed CD36 expression and CD36 gene in subjects who showed total lack of myocardial 123I-BMIPP accumulation, and, vice versa, evaluated myocardial 123I-BMIPP uptake in subjects with CD36 deficiency. Four unrelated subjects were evaluated, Two were found to have negative myocardial LCFA accumulation by 123I-BMIPP scintigraphy, after which the expression of CD36 on their platelets and monocytes was analyzed. Remaining two subjects were identified as CD36 deficiency by screening, then 123I-BMIPP scintigraphy was performed. Expression of CD36 on platelets and monocytes was measured by flow cytometric analysis. The molecular defects responsible for CD36 deficiency was detected by allele-specific restriction enzyme analysis. CD36 expression was totally deficient in all 4 subjects on both platelets and monocytes. Two subjects were homozygous for a 478C-->T mutation. One was heterozygous for the dinucleotide deletion of exon V and single nucleotide insertion of exon X, and remaining one was considered to be heterozygous for the dinucleotide deletion of exon V and an unknown gene abnormality. All cases demonstrated a completely negative accumulation of myocardial LCFA despite of normal myocardial perfusion, which was evaluated by thallium scintigraphy. In addition, all cases demonstrated apparently normal hepatic LCFA accumulation Thus, these findings suggested that CD36 acts as a major myocardial specific LCFA transporter in humans.
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ALG-2 is a 22 kDa EF-hand type Ca2+-binding protein associated with lymphocyte apoptosis. Comparison of the primary structure of ALG-2 with those of EF-hand type proteins revealed that it belongs to the penta-EF-hand (PEF) protein family including the small subunit of calpain. We established a convenient method for the purification of the recombinant mouse ALG-2 expressed in Escherichia coli. The recombinant protein was first pelleted from a lysate in the absence of a Ca2+-chelator, and then extracted with buffer containing EDTA/EGTA followed by purification by conventional column chromatographies. Estimation of the molecular mass by gel filtration suggested that the recombinant ALG-2 occurred as a monomeric form. Ca2+-dependent precipitation was blocked by inclusion of non-ionic detergent Triton X-100, suggesting hydrophobic self-aggregation at high concentrations of the protein. The N-terminal deletion mutant lacking the hydrophobic non-PEF region was found to be more soluble than the wild type in the presence of Ca2+. Analysis using a fluorescent hydrophobicity probe indicated that ALG-2 exposed a hydrophobic surface in a Ca2+-concentration dependent manner, the half-maximal effect occurring at approximately 6 microM. Mg2+ was not effective for the conformational change. On Western blotting, ALG-2 was detected in particulate fractions from cultured mammalian cells, suggesting the association of the protein with macromolecules in the cells.
A human fibroblast cDNA expression library was screened for cDNA clones giving rise to flat colonies when transfected into v-Ki-ras-transformed NIH 3T3 cells. One such gene, RECK, encodes a membrane-anchored glycoprotein of about 110 kDa with multiple epidermal growth factor-like repeats and serine-protease inhibitor-like domains. While RECK mRNA is expressed in various human tissues and untransformed cells, it is undetectable in tumor-derived cell lines and oncogenically transformed cells. Restored expression of RECK in malignant cells resulted in suppression of invasive activity with concomitant decrease in the secretion of matrix metalloproteinase-9 (MMP-9), a key enzyme involved in tumor invasion and metastasis. Moreover, purified RECK protein was found to bind to, and inhibit the proteolytic activity of, MMP-9. Thus, RECK may link oncogenic signals to tumor invasion and metastasis.
BACKGROUND: Idiopathic restrictive cardiomyopathy is a rare disease characterized by diastolic dysfunction, and the pathogenesis of the stiff heart remains unclear. The purpose of this study was to analyze the subpopulation of collagen fibers and determine the expression of matrix metalloproteinase in restrictive cardiomyopathy. METHODS AND RESULTS: In endomyocardial biopsy specimens obtained from seven patients with restrictive cardiomyopathy, collagen fiber types I, III, and IV, and matrix metalloproteinase- and two were observed by light and electron microscopy, using monoclonal antibodies. Type I collagen was less prominent in the interstitium, whereas the immunoreactivity for type III collagen was marked. The immunoreactivity against matrix metalloproteinase-1 was observed along with types I and III collagen fibers and in the cytoplasm of some fibrocytes/fibroblasts. The matrix metalloproteinase-1 tended to increase when the reactivity against types I and III collagen was prominent. Both type IV collagen and matrix metalloproteinase-2 were observed along arterial walls and the basement membrane of cardiocytes. CONCLUSIONS: Increased type III collagen may play an important role as the cause of left ventricular stiffness in restrictive cardiomyopathy. The matrix metalloproteinase appeared to be involved in a cascade of collagen synthesis and the remodeling of the heart in patients with restrictive cardiomyopathy.
DBA/2 inbred mice spontaneously develop myocarditis and a unique form of subepicardial inflammation of the right ventricle characterized by a prominent eosinophilic infiltrate with calcinosis. We studied this myocarditis using light microscopy and both transmission and analytical X-ray electron microscopy, paying particular attention to eosinophil-associated cardiocyte injury. At 5 weeks of age, many eosinophils and mononuclear cells (MNCs) were seen in the subepicardium of the right ventricle. Electron microscopy showed that cardiocytes underwent degenerative changes, including myofibrillar lysis, accumulation of Z-band material and mitochondrial inclusions, and rupture of plasma membranes. The infiltrating eosinophils appeared to be activated, and cells with cytoplasmic vacuoles, suggestive of degranulation, were noted. The myocardial injury was most severe in the 7th week and healed with myocardial fibrosis and calcinosis by the 8th week. Analytical X-ray electron microscopy showed that the calcinosis was initiated in mitochondrial inclusions of injured cardiocytes. The peripheral eosinophil count did not increase during the course of the disease, but there was a positive correlation between the ratio of eosinophils to infiltrated white blood cells (Eo/WBCs) in the right ventricle and the severity of myocardial damage. Eosinophils may play a significant part in subepicardial cardiocyte injury seen in DBA/2 mice.
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A case is presented of endocarditis that was affecting a prosthetic ball valve (Starr-Edwards) and which was caused by Gemella species. A 57-year-old man was admitted with a 3-day history of abdominal pain with fever. At the time of admission, his temperature was 37.7 degrees C and laboratory tests showed elevated inflammatory parameters and an increased neutrophil count. However, transthoracic echocardiogram showed no vegetation. During hospitalization, Gemella spp. were detected by blood culture, and a transesophageal echocardiogram showed vegetation on the prosthetic valve. He was treated with intravenous ampicillin and astromycin, and also underwent valve replacement. This is the first case in Japan of infective endocarditis of a prosthetic valve due to Gemella spp.
In patients with malignant lymphoma, the first signs and symptoms are frequently noncardiac and clinical manifestations of cardiac involvement are often nonspecific. This case report presents a patient with malignant lymphoma whose first manifestation was characteristic of heart failure, mainly due to diastolic dysfunction, and whose postmortem examination revealed massive myocardial invasion.
We describe the clinical manifestations of a patient with Churg-Strauss syndrome who presented with severe acute cardiac involvement and whose disease evolved to dilated cardiomyopathy (DCM), with special reference to the histopathological findings. Endomyocardial biopsies, conducted sequentially, three times within 10 months, revealed severe eosinophilic endomyocarditis in the acute phase, interstitial fibrosis in the subacute phase, and endocardial thickening with mural thrombi, at 10 months. Although acute inflammation associated with elevation of eosinophil granule proteins subsided with steroid therapy, left ventricular dilatation with reduced contractility progressed. A subgroup of DCM is not considered to be idiopathic but, rather, an aftereffect of hypereosinophilic heart disease.
Group B Coxsackieviruses are a common cause of myocarditis. To detect the viral genome and its localization in the myocardium, we examined C3H/He mice with Coxsackievirus B3 (CVB3) myocarditis on days 5, 8, and 14 after inoculation by the reverse transcriptase polymerase chain reaction and by in situ hybridization. Sense and antisense CVB3 RNA were detected in the myocardium of all mice up to day 14 by reverse transcriptase polymerase chain reaction. Light microscopic in situ hybridization with a cDNA probe for CVB3 showed clusters of positive signals in the areas of myocardial necrosis and cell infiltration. With electron microscopic in situ hybridization, CVB3 RNA was detected in the cytoplasm of cardiocytes, between the myofibrils, near the mitochondria, and in tubular or vesicular structures. Viral RNA was also detected in necrotic debris, in the cytoplasm of macrophages, and in the cytoplasm of interstitial fibroblasts. These findings suggest that CVB3 RNA is replicated in the cytoplasm of cardiocytes, transferred into tubular or vesicular structures, released into the interstitium, and phagocytosed by macrophages. Some positive signals were also detected in the cytoplasm of cardiocytes showing close contact with infiltrating lymphocytes, suggesting that the lymphocytes recognized virus-infected cardiocytes and caused cell-mediated immune cardiocyte damage.
Myocarditis is a rare complication of influenza infection but is occasionally fatal. Recent application of percutaneous cardiopulmonary support and/or intraaortic balloon pumping to the serious case of viral myocarditis brought an good prognosis. We should recognize that the patient with viral infection such as influenza may have myocarditis and should make an early diagnosis for adequate treatment in time. To avoid misdiagnosis we must know characteristic symptoms and signs of cardiac involvement during influenza infection.
Enteroviruses (EVs), especially group B coxsackieviruses, have been implicated in the pathogenesis of myocarditis and dilated cardiomyopathy (DCM). To determine whether a specific type of EV is present in DCM hearts, we examined the genotypes of EVs detected in endomyocardial biopsies and pericardial effusions by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis. Positive PCR results were obtained from biopsies in 6 (19 percent) of 31 patients with DCM, 5 (18 percent) of 28 with myocarditis, 5 (22 percent) of 23 with other cardiac diseases, and from pericardial effusions in 4 (57 percent) of 7 patients with pericarditis. SSCP profiles of most of the clinical samples were different and were not identical to any of the standard group B coxsackie viruses. Our findings suggest that EV genomes are involved in the myocardium of patients with various cardiac conditions and that a particular type of EV is not present in DCM hearts.
Enterovirus genotypes were identified rapidly by reverse (RT-PCR) followed by single-strand conformation polymorphism (SSCP) analysis. The primer pair was chosen from the highly conserved sequence at the 5' non-coding region of enterovirus genomes. RT-PCR amplified a 154 bp sequence in all samples from 14 serotypes of enteroviruses, including group A and B Coxsackie viruses, echoviruses and polioviruses. SSCP analysis of these products revealed different electrophoretic profiles. Thus, SSCP analysis will be useful for differentiating the genotypes of enteroviruses, and may be applicable for rapid diagnosis of enteroviral infection.