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M J Sole

Publications and source records attributed to M J Sole.

At least 37 records · Page 2Linked to original sources
PubMed1993

Characterization of the GArC motif. A novel cis-acting element of the human cardiac myosin heavy chain genes.

A positive element between positions -924 and -851 and a negative element between -851 and -762 of the 5'-upstream region of the alpha-myosin heavy chain gene were identified through transient transfection assays in primary cultures of neonatal rat heart cells. Subsequent DNase I protection analysis revealed almost identical footprints at two positions (GAAAAATCT at -904 to -896 and GAAAATCT at -823 to -816). We have designated this sequence the GArC motif (for G,AT-rich,C). Gel mobility shift assays demonstrated the formation of specific complexes with GArC oligomers when either rat heart, rat liver, or HeLa cell nuclear extracts were used. Competition studies with unlabeled GArC oligomers resulted in a loss of binding. Oligomers were also made to the Xenopus cytoskeletal actin serum response element and to a segment of the alpha-MyHC gene (AT-core), each with a similar AT-rich core sequence. No detectable loss of binding resulted from the addition of an excess of either of these unlabeled oligomers. Southwestern blot analysis identified several proteins which interacted with the GArC element, suggesting the presence of a group of related trans-acting factors. Analysis of a sequence in the beta-MyHC gene with the same AT-rich core was negative, suggesting a role for the bases surrounding the protected area in binding. We propose that the GArC motif, together with its associated trans-acting factor(s), provides a novel mechanism of transcriptional control in addition to those previously reported for the cardiac myosin heavy chain genes.

Animals↗
PubMed1993

Viral myocarditis: a paradigm for understanding the pathogenesis and treatment of dilated cardiomyopathy.

Although an etiologic link between viral myocarditis and idiopathic dilated cardiomyopathy has long been recognized, the actual extent of this relation has been uncertain. In this review, we examine recent developments in the molecular analysis of endomyocardial biopsy specimens, particularly techniques for gene amplification, which have unequivocally confirmed this relation and given us some insight into its significance. In addition, we show that viral myocarditis in a murine model is associated with spasm of the coronary microvasculature, leading to myocyte necrosis, fibrosis, calcification and cardiac dilation. These findings are similar to those seen in the hearts of genetically cardiomyopathic hamsters, rats and humans with hypertension and diabetes, rats after acute brain injury and models of Chagas' disease. Treatment of microvascular spasm with verapamil, captopril or alpha 1-adrenergic blocking agents appears to interrupt this pathway and has been shown to markedly impede the evolution of dilated cardiomyopathy in the genetic hamster model and a murine model of myocarditis. There is some suggestion that digitalis, though beneficial during cardiac decompensation, may actually be detrimental when administered during the early stages of myocardial disease. These experiments have led to a new paradigm for the pathogenesis of cardiomyopathy after viral myocarditis, as well as a general hypothesis for the pathogenesis of some types of dilated cardiomyopathy. They also suggest that the selection of therapeutic agents for some forms of dilated cardiomyopathy may differ significantly between the early and late stages of the disease.

Animals↗
PubMed1993

Structural organization of the human cardiac alpha-myosin heavy chain gene (MYH6).

The human myocardium expresses two cardiac myosin heavy chain (MyHC) isoforms, alpha and beta, that exist in tandem array on chromosome 14q12. We have previously sequenced the entire human cardiac beta-MyHC gene and now report the complete nucleotide sequence of the human cardiac alpha-MyHC, encompassing 26,159 bp as well as the entire 4484-bp 5'-flanking intergenic region. The gene (MYH6) consists of 39 exons, 37 of which contain coding information. The 5'-untranslated region is split into 3 exons, with the third exon containing the AUG translation initiation codon. With the exception of the 13th intron of the human cardiac beta-MyHC, which is not present within the alpha-isogene, all exon/intron boundaries are conserved. Conspicuous sequence motifs contained within the alpha-MyHC gene include four Alu repeats, a single (GT)n element, and a homopurine-homopyrimidine tract containing 23 GAA repeating units followed by 10 GAG repeating units. Comparison of the encoded amino acid sequence with a previously reported human alpha-MyHC cDNA sequence reveals several potential polymorphisms.

Amino Acid Sequence↗
PubMed1993

Quantitation of enteroviral RNA by competitive polymerase chain reaction.

The polymerase chain reaction (PCR) is a new diagnostic technique for the detection of enteroviral infection; however, it currently provides only qualitative results. The aim of this study was to adapt PCR for the accurate quantitation of enteroviral RNA in clinical specimens. For this purpose, we designed a standard RNA which was homologous to sequences at the 5' end of the coxsackie B3 enterovirus genome but contained a single-base-pair mutation which created a novel internal restriction site. Serial dilutions of this standard template RNA were mixed with a fixed concentration of coxsackie B3 enterovirus RNA. The viral and standard templates were reversed transcribed to cDNA and coamplified by PCR, and a comparison of the radioactive PCR products was made. Since the templates were both present in a single reaction tube and competed for the same primers, the ratio of products remained proportional throughout the amplification process. By this approach, a fourfold-difference in viral titer was clearly distinguishable. Moreover, we were able to accurately quantitate as few as 15 50% tissue culture infectious doses, which reflects common clinical viral titers. This study lays the foundation for quantitation of enteroviral RNA in clinical specimens and establishes a technique that can readily be applied to the diagnosis of enteroviral infection.

Base Sequence↗
PubMed1992

The genetic basis of hypertrophic cardiomyopathy.

In this article we review the techniques of molecular biology as they apply to the elucidation of the genetic basis of hypertrophic cardiomyopathy. We review the evidence for linkage to chromosome 14 and the specific mutations described to date. The evidence for genetic heterogeneity is presented. We speculate on the pathophysiology of the disease from the perspective of the known molecular defects and review the clinical implications the evolving information may have.

Cardiomyopathy, Hypertrophic↗
PubMed1992

Persistence of viral genome into late stages of murine myocarditis detected by polymerase chain reaction.

BACKGROUND: Enteroviruses have been considered as the most common etiologic agents in clinical myocarditis and dilated cardiomyopathy; however, their pathogenetic role remains unknown. Hence, the relation of viral replication and development of cardiomyopathy has been determined in a murine model of myocarditis by evaluating the persistence of viral genome during acute and chronic stages of myocarditis by means of Northern blot hybridization and polymerase chain reaction (PCR). METHODS AND RESULTS: DBA/2 mice (n = 146) were injected peritoneally with 10 plaque-forming units of encephalomyocarditis (EMC) virus, and the control mice (n = 33) were injected with normal saline. Animals were randomly killed at 4, 7, 10, 14, 21, 28, 35, and 42 days after infection. Histology revealed acute myocardial necrosis with massive inflammatory cell infiltrate peaking on day 14 followed by increasing fibrosis and declining chronic inflammation features compatible with dilated cardiomyopathy between days 21 and 42. Northern blot analysis of control and infected hearts showed detectable viral RNA in the infected hearts initially at day 4, peaking by day 7, diminishing between day 7 and day 14, and absent at day 21 and day 28. However, potential viral remnants present in low quantities and undetectable by Northern blot were further detected by PCR followed by confirmation with an internal oligonucleotide probe after day 14 up to day 42. CONCLUSIONS: Viral RNA signals on Northern blot showed a strong correlation with massive myocyte necrosis on day 14, but the viral RNA fragment was consistently detectable into late stages of cardiomyopathy on days 21, 28, 35, and 42 by PCR. This indicated that the mature virions are fully developed early in infection and are capable of persisting in the myocardium after virus-mediated myocytolysis stage. Therefore, PCR is an extremely sensitive method for detecting residual viral genome and viral persistence in the myocardium and may offer insights into the pathogenesis of chronic myocarditis leading to dilated cardiomyopathy.

Animals↗
PubMed1992

Verapamil ameliorates the clinical and pathological course of murine myocarditis.

The effects of the calcium channel blocking agent, verapamil, were studied in a murine model of viral myocarditis. Three groups of 8-wk-old DBA/2 mice (n = 25 each) were inoculated with 10 plaque-forming units of encephalomyocarditis virus and randomized to three treatment regimens. Group 1 mice received verapamil intraperitoneally (5 mg/kg per d) for 7 d before infection, followed by verapamil orally (mean dose of 3.5 mg/mouse per d) in drinking water during infection. Group 2 mice received only verapamil orally starting on day 4 after infection, coincident with peak viremia. Group 3 (infected control) received no verapamil in regular drinking water after viral inoculation. Additional control animals were studied in group 4 (n = 21), consisting of uninfected control animals receiving intraperitoneal and oral verapamil at doses identical to group 1, and in group 5 (n = 21), consisting of uninfected and untreated controls. Animals were randomly killed from each group (n = 7) at 7, 14, and 28 d after infection. Routine histology was performed blindly on an apical slice of each heart and semi-quantitatively graded for inflammation, necrosis, calcification, and fibrosis on a scale of 0-4. Digital planimetry was performed to measure the absolute and relative areas of inflammation and necrosis. The pretreated animals in group 1 showed marked reduction in inflammation and necrosis (score of 3.7 +/- 1.4 vs. 8.7 +/- 2.0 in group 3 on day 14, P < 0.05) and were indistinguishable from the posttreated group 2 mice (score of 4.0 +/- 1.5 vs. 8.7 +/- 2.0 in group 3 on day 14, P < 0.05). All the uninfected control animals (groups 4 and 5) showed no myocardial lesions whether treated with verapamil or not. Quantitative planimetry confirmed decreased inflammation and necrosis (2.0 +/- 3.3% in group 1 and 3.5 +/- 3.1% in group 2 vs. 21.9 +/- 22.6% in group 3 on day 14). Untreated infected hearts injected with liquid silicone rubber exhibited extensive areas of focal microvascular constriction and microaneurysm formation; verapamil treatment in either group 1 or 2 completely abolished these abnormalities, resembling uninfected controls in groups 4 or 5. We conclude that verapamil, whether given before infection or after peak viremia in an encephalomyocarditis model of murine myocarditis, significantly reduces the microvascular changes and myocardial necrosis, fibrosis, and calcification leading to cardiomyopathy. This suggests the potentially important role of calcium and microvascular spasm in the pathogenesis of viral myocarditis leading to dilated cardiomyopathy, and may have future therapeutic implications.

Animals↗
PubMed1991

Isolation and characterization of a previously unrecognized myosin heavy chain gene present in the Syrian hamster.

A full length (25,000 base-pair) myosin heavy chain gene completely contained within a single cosmid clone was isolated from a Syrian hamster cosmid genomic library. Sequence comparison of the 3' untranslated region indicated the presence of a 75% homology with the rat embryonic myosin heavy chain gene. Extensive 5' flanking region regulatory element conservation was also found when the sequence was compared to the rat myosin heavy chain gene. S1 nuclease digestion analysis, however, indicated that the Syrian hamster myosin heavy chain gene exhibited expression in adult Syrian hamster ventricular tissue, as well as the adult vastus medialis, a fast twitch skeletal muscle. Expression also appears to be enhanced in myopathic relative to control hearts. This myosin heavy chain gene is neither the alpha nor beta cardiac myosin heavy chain gene, but is a unique, previously unrecognized, myosin heavy chain gene present in both myocardial and skeletal muscle tissues.

Animals↗
PubMed1991

Inefficient muscarinic transduction in cardiomyopathic Syrian hamsters.

Regulation of cyclic AMP (cAMP) production and muscarinic binding were studied in highly washed left ventricular membranes from spontaneously cardiomyopathic Syrian hamsters (TO strain). Basal production of cAMP was decreased relative to that in random-bred (RB) controls, with proportionally similar decreases in stimulated production elicited by 7 beta-deacetyl-7 beta-(gamma-N-methylpiperazino)-butyryl forskolin and by the beta-adrenergic agonist isoproterenol. GTP-stimulated production of cAMP was inhibited fully by the muscarinic agonist carbachol in tissue from controls, but only partially in tissue from TO hamsters. Total muscarinic binding, as revealed by N-[3H]methylscopolamine, was similar in the two strains. Competition between carbachol and the radioligand revealed at least three classes of sites for the agonist, the apparent affinities of which were insensitive to the disease. Upon the addition of guanylyl imidodiphosphate (GMP-PNP, 0.1 mM), there was a disease-dependent redistribution such that the sites appeared to be predominantly of low affinity for the agonist in RB tissue and predominantly of medium affinity in TO tissue. The potency of GMP-PNP in mediating the change in carbachol binding apparently was unaffected by the disease. The loss of muscarinic regulation of cAMP production in TO left ventricular tissue appears to reflect a disease-related change in the coupling of muscarinic receptors to inhibitory GTP-binding proteins.

Adenylyl Cyclases↗
PubMed1991

Dihydropyridine receptor binding sites in the cardiomyopathic hamster heart are unchanged from control.

An increase in the number of voltage dependent calcium channels has been implicated in the overload of calcium found in cardiac tissue of the cardiomyopathic hamster. We examined the binding of [3H]-(+)PN200110 to dihydropyridine receptors in cardiac muscle membranes from TO cardiomyopathic hamsters. When compared to random bred controls, there were no differences in either the Bmax or the KD for [3H]-(+)PN200110 binding using homogenates from 35 to 41-day-old TO cardiomyopathic hearts. In 8 to 9-month-old myopathic animals there were only small decreases in Bmax with no change in KD. We suggest that the calcium overload observed in cardiomyopathic hamster heart may not be due to an increased density of calcium channels as estimated by high affinity dihydropyridine receptor binding sites.

Animals↗
PubMed1991

Pathologic fibrosis and matrix connective tissue in the subaortic myocardium of patients with hypertrophic cardiomyopathy.

To evaluate scar-type and matrix connective tissue and to assess their role in the diastolic dysfunction of hypertrophic cardiomyopathy, surgically resected subaortic myectomy specimens and several autopsy hearts from patients with hypertrophic cardiomyopathy were studied. Eighteen specimens were differentially stained by a newly developed method that precisely determines relative collagen content; these tissues were compared with postmortem hypertrophied and normal control subaortic specimens. Quantitation revealed a 72% higher level (36.5 vs. 22.1 micrograms collagen/mg protein) of stainable collagen in the hearts with hypertrophic cardiomyopathy than in hypertrophied control hearts. The endocardial plaque was quantitated morphometrically, and it constituted only 4.6 +/- 1.7% of the total increased collagen content in the cardiomyopathy specimens. For the matrix studies, the cardiomyopathy specimens were stained by a silver impregnation technique that identifies connective tissue elements not normally visible with routine histologic methods. There was a marked increase in content of all matrix components, both in areas of pathologic scarring and in "normal" zones. Whorls of matrix connective tissue were noted in regions of myocyte whorls, as well as independent of them. Thus, these studies revealed a striking increase of both scar-type and matrix connective tissue in hypertrophic cardiomyopathy. The extensive scarring and the pronounced interstitial and intercellular matrix connective tissue may contribute to the increased ventricular chamber stiffness and impaired relaxation in this disease.

Cardiomyopathy, Hypertrophic↗
PubMed1991

RNA transcription and translation in the hearts of normal and cardiomyopathic Syrian hamsters.

The cardiomyopathic Syrian hamster has an autosomal recessive defect that results in the development of an early onset cardiac myopathy leading to cardiac dysfunction and, eventually, complete heart failure. To assess the regulatory mechanisms modulating gene expression in the normal and myopathic myocardium, we investigated both RNA transcription and translation. Our results indicated that the incorporation of [3H]UMP into myocardial cell nuclear RNA decreased 10-fold from 7 to 210 days of age in the normal Syrian hamster. The incorporation of [3H]UMP was approximately 50% lower in the cardiomyopathic as compared with the normal Syrian hamster. RNA translation, as assessed by rabbit reticulocyte lysate in vitro translation, indicated that a coordinated 50% decrease in RNA translation occurred in normal Syrian hamster from 7 to 210 days of age. A further reduction of 20% in translation was found in cardiomyopathic Syrian hamster ventricular RNA translation as compared with matched random bred control groups. Two-dimensional polyacrylamide gel analysis of cell-free translated protein products demonstrated two myocardial peptides that were found to be consistently altered when the normal and cardiomyopathic Syrian hamsters were compared. These results indicate that transcription and translation decrease with age and that these processes are further downregulated, in an additive manner, with the genesis of the disease process.

Aging↗
PubMed1990

Detection of enterovirus RNA in myocardial biopsies from patients with myocarditis and cardiomyopathy using gene amplification by polymerase chain reaction.

Recent molecular studies have suggested that viral myocarditis frequently underlies human congestive cardiomyopathy; however, only moderately sensitive and specific techniques were used. Polymerase chain reaction (PCR) gene amplification is a sensitive, specific technique ideally suited for the diagnosis of viral disease in small tissue samples where low copy numbers of the viral genome may be present. Using PCR and high stringency condition, we screened biopsies taken from 48 patients with clinically suspected myocarditis or dilated cardiomyopathy. Five patients demonstrated positive enteroviral signals by PCR; two of them had myocarditis by pathology, whereas the other three had changes consistent with cardiomyopathy. Four other patients had myocarditis diagnosed by pathology from 3 months to 1 year earlier but were now negative by both PCR and pathology. Both pathology and PCR were negative for active myocarditis in all other patients. Ventricular samples taken from left ventricular myectomy in four additional patients with hypertrophic cardiomyopathy, normal human ventricle samples, and uninfected monkey kidney cells were also negative by PCR. This study supports a link between viral infection and dilated cardiomyopathy in some patients. PCR gene amplification provides a new diagnostic approach to patients with suspected myocarditis.

Biopsy↗
PubMed1990

Desipramine blocks augmented neurogenic vasoconstrictor responses to epinephrine.

The forearm vasoconstrictor response to lower body negative pressure (LBNP), a reflex stimulus to norepinephrine release, can be augmented by a prior brachial artery infusion of epinephrine. We wished to determine whether this sustained aftereffect of epinephrine could be replicated by systemic infusion and, if so, whether it could be prevented by prior uptake-1 blockade with desipramine. Eight normal men (mean age 30 years) were studied on two separate study days at least 1 week apart, 2.5 hours after taking, at random, either desipramine (125 mg p.o.) or placebo. Forearm vascular resistance was measured at rest and at the end of 6 minutes of LBNP at -40 mm Hg. This was done both before and 30 minutes after a 60-minute infusion of epinephrine (1.5 micrograms/min i.v.). From similar baselines, the forearm vasoconstrictor response to LBNP was significantly augmented 30 minutes after epinephrine on the placebo day (+17 +/- 4 vs. +12 +/- 3 resistance units, mean +/- SEM, p less than 0.01) but not on the desipramine day (+14 +/- 2 vs. +16 +/- 3 resistance units). The heart rate response to LBNP was also greater after epinephrine on the placebo day (+20 +/- 3 vs. +16 +/- 2 beats/min, p less than 0.05). Mean arterial pressure was higher after epinephrine infusion on the placebo (p less than 0.01) but not on the desipramine day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Myocardial catecholamines and the pathophysiology of heart failure.

The sympathetic nervous system contributes importantly to the clinical expression and, perhaps, to the course of myocardial failure. The failing heart exhibits both anatomic and functional defects in its sympathetic innervation and adrenergic receptor function. The nature of these abnormalities is at least partially dependent on the etiology of the underlying myocardial injury. Both efferent cardiac sympathetic tone and circulating catecholamines are elevated during the later stages of most forms of heart failure. This increase is not merely a reflex compensatory response but is also a reflection of defects in parasympathetic function, baroreceptor afferent nerve traffic, and regulation of sympathetic tone within the central nervous system through a serotonergic pathway. Prolonged stimulation of the heart may exhaust myocardial stores of norepinephrine and may lead to the destruction of sympathetic nerve terminals. Importantly, these abnormalities of autonomic function are distributed nonuniformly across the myocardium. Such heterogeneity can have profound effects on the temporal coordination of myocardial contraction and relaxation as well as the duration and configuration of the cardiac action potential and, thus, may contribute to both the mechanical and electrophysiological derangements seen in the failing heart. Therapy that makes sympathetic responses more uniform may improve the temporal coordination of excitation and contraction between innervated and denervated segments. This hypothesis might explain why both sympathetic agonists and antagonists may improve cardiac function since both types of drugs can restore the uniformity of neural stimulation.

Animals↗
PubMed1989

Characterization of human cardiac myosin heavy chain genes.

We have isolated and analyzed the structure of the genes coding for the alpha and beta forms of the human cardiac myosin heavy chain (MYHC). Detailed analysis of four overlapping MYHC genomic clones shows that the alpha-MYHC and beta-MYHC genes constitute a total length of 51 kilobases and are tandemly linked. The beta-MYHC-encoding gene, predominantly expressed in the normal human ventricle and also in slow-twitch skeletal muscle, is located 4.5 kilobases upstream of the alpha-MYHC-encoding gene, which is predominantly expressed in normal human atrium. We have determined the nucleotide sequences of the beta form of the MYHC gene, which is 100% homologous to the cardiac MYHC cDNA clone (pHMC3). It is unlikely that the divergence of a few nucleotide sequences from the cardiac beta-MYHC cDNA clone (pHMC3) reported in a MYHC cDNA clone (pSMHCZ) from skeletal muscle is due to a splicing mechanism. This finding suggests that the same beta form of the cardiac MYHC gene is expressed in both ventricular and slow-twitch skeletal muscle. The promoter regions of both alpha- and beta-MYHC genes, as well as the first four coding regions in the respective genes, have also been sequenced. The sequences in the 5'-flanking region of the alpha- and beta-MYHC-encoding genes diverge extensively from one another, suggesting that expression of the alpha- and beta-MYHC genes is independently regulated.

Amino Acid Sequence↗
PubMed1989

Rat brain regional preproenkephalin A messenger RNA levels are altered in genetic hypertension.

Considerable neuroanatomical and pharmacological evidence suggests that preproenkephalin A-derived peptides, particularly methionine-enkephalin, are involved in regulation of the cardiovascular system in both physiological and pathological states. In this study, we used a rat preproenkephalin A complementary DNA to determine whether proenkephalin A-derived peptides participate in the pathogenesis of hypertension as reflected by brain regional messenger RNA levels. Complementary DNA clones of the rat preproenkephalin A mRNA and rat small myelin basic protein mRNA were hybridized to total RNA extracted from hypothalamus, pons-medulla, thoracic cord, midbrain, and cerebellum of 3 1/2-week-old and 12-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. In 3 1/2-week and 12-week animals there were no differences in the levels of myelin basic protein messenger RNA between the two groups in any brain region. At 3 1/2 weeks, preproenkephalin A mRNA levels did not differ between normotensive and hypertensive strains. In contrast, at 12 weeks preproenkephalin A mRNA levels were increased in hypothalamus, midbrain, thoracic cord, and cerebellum of SHR relative to WKY. Preproenkephalin A mRNA was significantly reduced in the pons-medulla of SHR relative to WKY. Our findings provide evidence that alterations in brain regional preproenkephalin A mRNA levels are associated with the development of spontaneous hypertension in the rat.

Aging↗