To test the hypothesis that dobutamine-induced myocardial ischemia causes early-systolic asynchrony predominantly in the regional left ventricular wall, color kinesis (CK) images during dobutamine ...stress echocardiography (DSE) were recorded in 13 patients with coronary artery disease and in 10 patients without, all of whom showed normal wall motion at rest. Based on the visual interpretation of DSE and the angiographic findings, 21 segments in the short-axis images at the papillary muscle level were defined as ischemic, and 60 segments of the patients without coronary artery disease were defined as normal. The incremental fractional segmental area change (IFAC) was calculated at 33-ms intervals from the CK images. At the peak dose, IFACs during the first 33 and 33-67 ms were significantly lower in the ischemic segments than in the normal ones, and IFACs during 133-167, 200-233 and 233-267 ms were significantly higher in the ischemic segments. The ratio (peak/low dose) of the cumulative fractional area change at 100 ms gave the best sensitivity (= specificity) for differentiating the 2 groups (86%). Dobutamine-induced ischemia is characterized by an early-systolic asynchrony rather than a change in overall wall excursion and CK can provide an objective assessment of ischemia developing during DSE. (Circ J 2003; 67: 317 - 322)
Coronary vasomotor response to acetylcholine infusion was studied in a 69-year-old currently smoking man with enhanced insulin response to oral glucose load. Coronary angiogram showed no significant ...stenoses. Immediately after 20 microg acetylcholine infusion in the right coronary artery, angiographic no-flow, ischemic electrocardiographic changes, and anginal pain developed in the absence of epicardial coronary obstruction. While intracoronary infusion of isosorbide dinitrate was only partially effective, intracoronary infusion of nicorandil, an agent known to improve coronary microcirculation, completely resolved these changes. This is the first case reported so far suggesting that enhanced insulin response may be associated with acetylcholine-induced microvascular vasoconstriction. Microvascular vasoconstriction must be considered when a patient with insulin resistance presents with chest pain.
Myocardial viability is not synonymous with contractile reserve and identifiable in a significant percentage of dysfunctional myocardial segments without contractile reserve. The usefulness of ...ultrasonic tissue characterization by the phase-corrected magnitude of cyclic variation of integrated backscatter (MVIB) in chronic coronary artery disease is not fully validated. Thus, whether MVIB predominantly reflects the contractile reserve or myocardial viability of chronically dysfunctional myocardium was determined.
The MVIB of severely dysfunctional interventricular septum or posterior wall was measured in 34 consecutive patients with previous myocardial infarction. Dobutamine stress echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography were used as the standards of contractile reserve and myocardial viability, respectively.
Among 44 dysfunctional segments, only 15 were judged as having contractile reserve and 29 were judged as not by dobutamine stress echocardiography, whereas 26 segments showed myocardial viability using fluorine-18 fluorodeoxyglucose positron emission tomography and 18 did not. MVIB was greater in segments with than in those without contractile reserve (4.7 +/- 2.2 vs -1.4 +/- 4.9 dB, P < .0001), but there was considerable overlap between the groups. On the other hand, MVIB of segments with and without myocardial viability (4.1 +/- 2.6 vs -4.3 +/- 3.3 dB, P < .0001) was distinctly different and predicted myocardial viability with a sensitivity of 92% and a specificity of 94%.
For patients with chronic coronary artery disease, MVIB better reflects myocardial viability than it does contractile reserve. Ultrasonic tissue characterization, in concordance with fluorine-18 fluorodeoxyglucose positron emission tomography, is a sensitive method for detecting myocardial viability.
The VP7 and VP4 genome segments of human rotavirus strain Mc35 (Urasawa
et al., J. Infect. Dis. , 166, 227-234, 1992) were investigated. Analysis of its VP7 nucleotide and amino acid sequences ...confirmed that it belongs to G (or VP7) serotype 10; however, the nucleotide sequence homologies between Mc35 and the four G10 bovine strains examined were lower than those among the four G 10 bovine strains. The VP4 nucleotide and amino acid sequences of Mc35 were distinct (66.1-68.8% nucleotide and 64.9-70.0% amino acid homologies) from those of previously reported human and animal rotavirus strains representing different P (or VP4) types except for the strain K8 VP4, which was designated as type 3 of human rotavirus VP4 by Gorziglia
et al. (Proc. Natl. Acad. Sci. USA., 87, 7155-7159, 1990). The VP4s of the K8 and Mc35 strains showed a relatively high degree of homology (77.6% nucleotide and 86.0% amino acid sequence homologies) and were presumed to represent subtypes of type 3 human rotavirus VP4 (type 3A (K8 VP4) and type 39 (Mc35 VP4)).
Protein A of Staphylococcus aureus contains a polymorphic Xr-region characterized by a
tandem repeat of eight amino acid units. In this study, the diversity of genes encoding the
repeat regions and ...their relatedness among S. aureus strains was analyzed. Ten different
protein-A types characterized by repeat numbers 4–13 were identified in a total of 293 clinical
isolates. The protein-A type with 10 repeat units (10 repeats) in the Xr-region was most
frequently detected in methicillin-resistant S. aureus, whereas the majority of methicillin-
susceptible strains were distributed almost evenly into protein-A types with 7–11 repeats.
Strains that belonged to a single coagulase type were classified into multiple protein-A types,
e.g. strains with the common coagulase types II and VII were differentiated into 7 and 8
protein-A types, respectively. Nucleotide sequence analysis of the Xr-region of 42 representative strains revealed the
presence of 37 different genotypes (spa types), which were constituted by a combination of
several of 24 different repeat unit genotypes. Based on the similarity in arrangement of repeat
unit genotypes, 34 strains with different repeat numbers were classified into 5 genetic clusters
(C1–C5). The clusters C1, C2 and C3 consisted exclusively of strains with identical coagulase
types II, III, and IV, respectively. These findings suggested that the protein-A gene of S.
aureus has evolved from a common ancestral clone in individual clusters independently.
GTP binding protein-coupled receptor kinase 5 (GRK5) cDNA was cloned from the hearts of Syrian hamsters. The hamster GRK5 cDNA contained 1770 nucleotides encoding 590 amino acids, and the nucleotide ...sequence had 89.6% homology to the human homologue. An inbred cardiomyopathic hamster strain, J2N-k, was used to investigate the alteration of GRK5 mRNA expression in the setting of congestive heart failure. M-mode echocardiography revealed significant dilatation of the left ventricle and a decrease of left ventricular contractility in 20-week-old J2N-k hamsters compared with age-matched control hamsters, J2N-n. Semi-quantitative RT-PCR showed that GRK5 mRNA expression in the hearts of J2N-k was significantly higher than in those of J2N-n (J2N-k 60.3 ± 13.3, J2N-n 25.8 ± 17.2 arbitrary units, p < 0.005, n = 6 in each group). These results suggest that an enhanced GRK5 expression might play a role in the reduced responsiveness to catecholamines in failing hearts via β-adrenergic receptor phosphorylation.
We isolated five stable SA11 clones (TN-S1, TN-S2, TN-L1, TN-L2, and BN-S4) with different plaque sizes from two SA11 stocks. In polyacrylamide gel electrophoresis, the mobilities of the fourth, ...fifth, and seventh RNA segments of SA11 clones with large plaque size (TN-L1 and TN-L2) were faster than those of clones with small plaque size (TN-S1, TN-S2, and BN-S4). Nucleotide sequence determination of the fourth RNA segment identified a five-amino-acid difference in VP4s between the clones with large and small plaque sizes. The VP4 sequences of two clones with small plaque size (TN-S1 and BN-S4) were the same as the sequence of SA11-SEM reported by K. Nishikawa et al. (1988, J. Virol. 62, 4022-4026), while the VP4 sequences of the clones with large plaque size (TN-L1 and TN-L2) were similar, but not identical, to that reported by D. B. Mitchell and G. W. Both (1989, Nucleic Acids Res., 17, 2122). A single-gene reassortant, K8-L2.4, in which RNA segment 4 was derived from clone TN-L2 of SA11 virus and the other RNA segments were from strain K8, produced large plaques like TN-L2, suggesting that the five-amino-acid difference in VP4 between the clones with large and small plaque sizes might be associated with the difference in plaque size.
We previously reported that the VP7 gene from simian rotavirus SA11 with G-serotype 3(G3-VP7 gene) was preferentially selected in the genetic background of SA11 compared with the G1- or G2-VP7 gene. ...In the present study, selection of the G4-VP7 gene in competition with G1-, G2- or G3-VP7 gene in the SA11 background was analyzed through mixed infection experiments using SA11 and SA11-human rotavirus single-VP7 gene-substitution reassortants with G-serotypes 1, 2, and 4 (G1-, G2- and G4-reassortant). In virus clones from coinfection of SA11 and G4-reassortant, the frequency of G4 virus decreased to 7% at the 3rd passage and the G4 virus disappeared at the 10th passage, whereas the majority of the clones possessed G3 specificity. However, the predominance of either of the viruses coinfected was not observed in the mixed infection with G4-reassortant and G1- or G2-reassortant. Although growth kinetics of SA11 and G4-reassortant was similar. G4-reassortant showed significantly smaller plaque size than SA11, G1- and G2-reassortant did. These results indicated that the G3-VP7 gene from SA11 might be preferentially selected in the SA11 genetic background compared with the G4-VP7 gene, and suggested that the introduction of a single G4-VP7 gene may affect growth characteristics of recipient virus SA11. These results together with our previous findings suggested the significance of genetic compatibility between recipient viral genes and foreign VP7 gene in the development of multivalent reassortant rotavirus vaccines.
Department of Hygiene, Sapporo Medical College, South-1, West-17, Chuo-ku, Sapporo 060, Japan
Three anti-VP7 monoclonal antibodies (MAbs) which neutralized only two strains (K8 and S12) of five ...serotype 1 human rotaviruses (HRVs) were obtained, and neutralization epitopes recognized by these monotype-specific MAbs were analysed by epitope mapping and sequencing of the VP7 genes. Neutralization-resistant mutants of K8 and S12 were selected by the monotype-specific MAbs and serotype 1-specific MAbs prepared previously. Cross-neutralization tests between MAbs and neutralization-resistant mutants of K8 and S12 indicated that epitopes of monotype-specific MAbs operationally overlap with those of serotype 1-specific and cross-reactive MAbs recognizing the S1 region. Sequence analyses of the VP7 genes indicated that VP7s of strains K8 and S12, which belong to a monotype of serotype 1 viruses, possessed amino acids at positions 42 and 87 different from other serotype 1 HRVs. Furthermore, amino acid substitution sites of representative mutants of K8, selected by the monotype-specific MAbs, were identified at positions 96, 97 and 100. These results imply that amino acids in variable region B (amino acids 87 to 101) are involved in the monotype-specific neutralization epitope as well as serotype-specific neutralization epitopes.
Received 14 January 1991;
accepted 12 April 1991.
Rotavirus clones Aff5–10 and Aff5–16 isolated from a bovine rotavirus strain Aff5 possess NSP1 gene which has a point mutation generating a nonsense codon and a 500 base-deletion, respectively. As a ...result, the two Aff5 clones encode truncated NSP1 product which lacks cysteine-rich region forming zinc finger motif. In order to analyze reassortment of these mutated NSP1 gene with RNA segments from heterologous strains, we investigated a number of reassortant clones derived from coinfection with either Aff5–10, Aff5–16 or a reference strain Aff5–13 (possessing intact NSP1 gene) and either simian rotavirus SAff11 or human rotavirus KU. In coinfection with SAff11 and Aff5–13, selection rates of Aff5–13 segments in reassortants ranged approximately from 20 to 70% (46% for NSP1 gene). In contrast, in the reassortment between SAff11 and Aff5–10 or between SAff11 and Aff5–16, selection rates of NSP1 gene from Aff5–10 and Aff5–16 were only 1% (one clone) and 0%, respectively. In reassortants from crosses KU × Aff5-clones, selection rate of Aff5–13 NSP1 gene decreased to 15%, while 11 reassortants with Aff5–10 NSP1 gene (31%) and one reassortant with Aff5–16 NSP1 gene (2%) were isolated. Reassortants with Aff5–10 NSP1 possessed a single gene (segment 9 or 11) from KU in the genetic background of Aff5–10. One reassortant clone (cl-55) with Aff5–16 NSP1 gene possessed KU gene segments 3, 4, and 8–11. When single-step growth curves were compared, the reassortant cl-55 showed almost identical growth curve to that of KU, while KU showed a better replication than Aff5–16. These results indicated that although Aff5–10 or Aff5–16 NSP1 gene encoding the truncated NSP1 is selected into reassortants much less efficiently than normal NSP1 gene, the reassortants with the mutated NSP1 gene and RNA segments from heterologous strains normally replicated in cultured cells. Thus, cysteine-rich region of NSP1 was not considered essential for genome segment reassortment with heterologous virus.
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