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Biomedical subjects

E Domingo

Publications and source records attributed to E Domingo.

At least 217 records · Page 12Linked to original sources
PubMed1985

Hemodynamic evaluation of stenotic cardiac valves: I. Effect of ventriculography and atropine on mitral stenosis.

Mitral area is the parameter used for quantitating mitral stenosis (MS) severity. When mitral gradient (MG) is low and reduction of mitral valve area (MVA) might be critical, interventions presumably increasing mitral valve flow (MVF), such as stress or atrial pacing, have been carried out. The purpose of this study was to analyze in 28 patients the combined effect of left ventriculography (LVG) and intravenous atropine (ATR) in the hemodynamic evaluation of MS. The rationale for combining these two interventions is to add up the ATR-positive chronotropic effect to the LVG potentiation of cardiac output. The LVG plus ATR markedly accelerated heart rate (from 80 +/- 14 to 104 +/- 18 bts/min, P less than 0.001), mildly increased cardiac index (from 2.6 +/- 0.6 to 2.9 +/- 0.6 1/min/m2, P less than 0.05), and importantly increased MVF (from 136 +/- 30 to 172 +/- 46 ml/bt, P less than 0.001). Pulmonary wedge pressure increased (from 14 +/- 5 to 21 +/- 5 mmHg, P less than 0.001) because of an important increment of MG (from 12 +/- 6 to 18 +/- 7 mmHg, P less than 0.001). None of six cases with mild MS (MVA greater than 1.5 cm2) and nine of ten cases with severe MS (MVA less than or equal to 1.0 cm2) had MG after LVG plus ATR greater than 12 mmHg. The remaining case with severe MS and the two cases (out of 12) with moderate MS having MG after LVG plus ATR less than or equal to 12 mmHg had, at surgical evaluation, noncritically reduced MVA. This study shows that LVG plus ATR is a valid and easy intervention for increasing MVF during cardiac catheterization. It also allows the reclassification of patients with low baseline MG and reduced MVA into two subgroups: Cases with critically reduced MVA at surgery achieve a postintervention MG greater than 12 mmHg and those cases with noncritically reduced MVA achieve a postintervention MG less than or equal to 12 mmHg.

Adult↗
PubMed1985

Hemodynamic evaluation of stenotic cardiac valves: II. Modification of the simplified valve formula for mitral and aortic valve area calculation.

Since the introduction by Gorlin and Gorlin of the hydraulic formulae for calculating valve area, it has become the best parameter for quantitating valve stenosis. Recently Hakki et al proposed a simplified formula for valve area calculation that does not take into account either heart rate (HR) or left ventricular filling or ejection time. The purpose of this study was to analyze the validity of Hakki's formulae under different physiological conditions and to propose an easy correction to improve its accuracy. Our study suggests: (1) that an easy correction for heart rate in certain cases, dividing by 1.35 when HR less than 75 beats per min in mitral stenosis and when HR greater than 90 beats per min in aortic stenosis, significantly improves the accuracy and validity of Hakki's formulae (p less than 0.02 and p less than 0.05); (2) the instantaneous valve gradients (peak gradient for aortic stenosis and average of instantaneous early, middle, and late diastolic gradients for mitral stenosis) are as valid as mean planimetric gradients for valve area calculation. Thus the simplified formulae proposed in this study allow mitral and aortic valve area calculations by means of instantaneous gradients, cardiac output, and heart rate.

Adolescent↗
PubMed1985

In vitro synthesis of full-length influenza virus complementary RNA.

Influenza virus-specific RNA has been synthesized in vitro, using cytoplasmic or microsomal fractions of influenza virus-infected MDCK cells. The RNA polymerase activity was stimulated 5-30 times by priming with ApG. About 20-30% of the product was polyadenylated. Most of the in vitro product was of positive polarity, as shown by hybridization to strand specific probes and by T1 fingerprinting of the poly(A)+ and poly(A)- RNA segments encoding haemagglutinin and nucleoprotein. The size of poly(A)- RNA segments, determined on sequencing gels, was indistinguishable from that of virion RNA, whereas poly(A)+ RNA segments contain poly(A) tails approximately 50 nucleotides long. The size of in vitro synthesized RNA segments was also determined by gel electrophoresis of S1-treated double-stranded RNAs, obtained by hybridization of poly(A)+ or poly(A)- RNA fractions with excess of unlabelled virion RNA. The results of these experiments indicate that poly(A)- RNA contains full-length complementary RNA. This conclusion is further substantiated by the presence of additional oligonucleotides in the T1 fingerprints of in vitro synthesized poly(A)- haemagglutinin or nucleoprotein RNA, selected by hybridization to cloned DNA probes corresponding to the 3' termini of the genes.

Animals↗
PubMed1985

Direct non-invasive techniques for assessing coronary bypass graft patency.

Venous digital subtraction angiography (vDSA) and computed tomography (CT) are two non-invasive techniques that allow direct imaging of coronary grafts. Neither of them is 100% accurate when compared to selective angiography. We studied 52 patients with 107 coronary grafts (101 saphenous and 6 mammary artery grafts) by CT and vDSA. Fifty patients had control selective angiography and 2 had control digital arterial aortography. CT correctly diagnosed 88 of the 95 patent grafts and 8 out of the 12 occluded grafts (in 1 patient 3 patent grafts could not be well analyzed owing to artifacts from pacemaker wires). vDSA correctly identified 93 patent grafts and the 12 occluded grafts, allowing the correct diagnosis of the 11 non/or misdiagnosed CT grafts. CT allowed the correct identification of the 2 misdiagnosed vDSA grafts. These results show that when there was agreement between CT and vDSA there were no diagnostic errors and that the combination of these two non-invasive techniques may avoid selective angiography for studying coronary bypass graft patency.

Aged↗
PubMed1985

Establishment of cell lines persistently infected with foot-and-mouth disease virus.

Cell lines persistently infected with foot-and-mouth disease virus (FMDV) have been established by growth of BHK-21 (c-13) or IBRS-2 (c-26) that survived standard cytolytic infections with FMDV. They maintain cytoplasmic FMDV RNA sequences, as shown by dot blot hybridization tests, using cloned FMDV cDNA as probes. Cell line C1-BHK-Rc1 was derived by infection of cloned BHK-21 c1 cells and plaque-purified FMDV C-S8 c1. Indirect immunofluorescence assays indicated the presence of FMDV antigens. It was resistant to superinfection by FMDV C-S8 c1, O-S7, or A5, but not by encephalomyocarditis virus (EMCV), vesicular stomatitis virus (VSV), or Semliki forest virus (SFV). Infectious FMDV was detected in the culture medium only up to cell passage 65. The virus isolated from C1-BHK-Rc1 cells showed decreased plaque size and diminished yield in infections at 42 degrees. Multiple mutations in the intracellular FMDV RNA have been detected by T1 oligonucleotide fingerprinting of genomic RNA segments hybridized to FMDV cDNA fragments. At late cell passages, when no infectious FMDV is detected, cells continue to express viral antigens and FMDV RNAs with deletions of up to 3 kb have been identified by Northern blot analysis. We conclude that persistent infections of cell cultures with FMDV are readily established and that multiple genetic and phenotypic variations occur in the virus during persistence.

Animals↗
PubMed1985

Oriented synthesis and cloning of influenza virus nucleoprotein cDNA that leads to its expression in mammalian cells.

The influenza virus nucleoprotein gene has been cloned by a procedure that involves direct cDNA synthesis onto the primer-vector pBSV9, a pBR322-SV40 recombinant plasmid. dT-tailed pBSV9 was used to prime the synthesis of cDNA on a template of in vitro synthesized viral mRNA. The synthesis of ds-cDNA was initiated by a specific oligodeoxynucleotide and the resulting recombinant was circularized by intramolecular ligation. Recombinant pSVa963 contained the viral nucleoprotein gene directly fused to the SV40 early promoter region included in pBSV9 and followed by a dA:dT tail and the SV40 polyadenylation signal. When pSVa963 was used to transfect COS-1 cells, the presence of three NP-specific mRNAs of 1600, 1900 and 2500 nucleotides in length could be detected. Pulse labelling experiments of COS-1 transfected cells and immunobinding to a nucleoprotein monoclonal antibody indicated the synthesis of nucleoprotein. This nucleoprotein accumulated in the nucleus of transfected cells at a level similar to that found in infected cells. The vector and method described may be useful for the specific cloning and expression of any mRNA for which a 5'-terminal sequence is known.

Animals↗
PubMed1985

The quasispecies (extremely heterogeneous) nature of viral RNA genome populations: biological relevance--a review.

We review evidence that cloned (or uncloned) populations of most RNA viruses do not consist of a single genome species of defined sequence, but rather of heterogeneous mixtures of related genomes (quasispecies). Due to very high mutation rates, genomes of a quasispecies virus population share a consensus sequence but differ from each other and from the consensus sequence by one, several, or many mutations. Viral genome analyses by sequencing, fingerprinting, cDNA cloning etc. indicate that most viral RNA populations (quasispecies) contain all possible single and double genomic site mutations and varying proportions of triple, quadruple, etc. site mutations. This quasispecies structure of RNA virus populations has many important theoretical and practical implications because mutations at only one or a few sites may alter the phenotype of an RNA virus.

Base Sequence↗
PubMed1985

Sequence of the viral replicase gene from foot-and-mouth disease virus C1-Santa Pau (C-S8).

The nucleotide sequence of the region including the viral replicase gene, the carboxy terminus of protein P18, and the 3'-extracistronic region of foot-and-mouth disease virus (FMDV) type C1-Santa Pau (C-S8) has been determined from previously cloned cDNA fragments [Villanueva et al., Gene 23 (1983) 185-194]. The comparison with the corresponding gene segments of FMDV of serotypes A or O shows base substitutions in 7.2-8.6% of residues in the replicase gene with no insertions or deletions. This is about fourfold lower variation than found for the region encoding capsid protein VP1 of the corresponding viruses. Intermediate variability (substitution at 16.1-23.6% positions) exists in the 3'-extracistronic region, including point mutations, insertions and deletions. The predicted amino acid sequence of the replicase gene indicates that 75.5-82.6% of mutations are silent and that 93.4% of amino acids are conserved in the four FMDV replicases. The frequency of certain types of silent mutations and of rare codon usage is significantly lower for the replicase gene than for the protein VP1 coding region.

Amino Acid Sequence↗
PubMed1984

Plasmid vectors based on Tn10 DNA: gene expression regulated by tetracycline.

The regulatory region of the tetracycline resistance determinant from transposon Tn10 has been used to construct plasmid vectors for gene expression regulated by tetracycline. Plasmids pRS tetBam-8 and pRS tetBam-16 include the tet regulatory region, the segment coding for the first four amino acids of the tetracycline resistance protein (tetA protein), and a linker region with SalI, HpaII, and BamHI restriction sites for gene fusions. Plasmid pTB-1, a derivative of pRS tetBam-8 and of the beta-galactosidase gene-containing plasmid pMC1403, constitutively expresses a tetA fragment-beta-galactosidase fusion protein. If a multicopy runaway replication plasmid, pMOBglII-16 that includes a 2.7-kb BglII DNA fragment from Tnl10 that provides tetR protein is present along with pTB-1, the expression of beta-galactosidase is reduced eightfold. Tetracycline acts as an inducer of the system and restores the level of beta-galactosidase activity measured in transformants containing pTB-1 alone. Plasmid mutants unable to produce active tetR protein are ineffective in reducing expression. Escherichia coli carrying plasmids that express both tetA protein and tetR protein show an increase in the tetracycline resistance level after incubation with the drug. The observations are consistent with the previously proposed mechanism of regulation of tetracycline resistance in Tn10.

DNA Transposable Elements↗
PubMed1983

Evolution of the influenza virus neuraminidase gene during drift of the N2 subtype.

The complete genetic information for the neuraminidase (NA) gene of influenza virus A/Bangkok/1/79 has been cloned by in vitro synthesis of dsDNA, insertion into pBR322 plasmid, and transformation of Escherichia coli. The nucleotide sequence of the NA gene has been determined by the Maxam and Gilbert method. It is 1466 nucleotides long and contains a single open reading frame with a coding capacity for 469 amino acids. When compared to the NA genes of the N2 strains A/Victoria/3/75, A/Udorn/72, A/NT/60/68, and A/RI/5-/57, 90% of the nucleotide positions and 87% of the amino acid positions remained invariant. Forty-two nucleotide changes and 14 amino acid changes accumulated in the period 1975-1979, but the general structure of the protein appeared to remain constant.

Amino Acid Sequence↗
PubMed1983

Multiple genetic variants arise in the course of replication of foot-and-mouth disease virus in cell culture.

The genetic heterogeneity generated upon passage of foot-and-mouth disease virus (FMDV) in cell culture has been evaluated by T1-oligonucleotide fingerprinting of genomic RNA. Plaque-purified FMDV O-S7 and C-S8 were propagated by serial low multiplicity infections of BHK-21 (c-13) or IBRS-2 (c-26) cells. In independent parallel passage of the same virus, different oligonucleotide variations were fixed in the RNAs. T1-oligonucleotide fingerprinting of RNA from 34 individual viral clones derived from two passaged populations shows an extensive heterogeneity, with some mutations present in only one of the cloned genomes analyzed. Some FMDV variants are phenotypically distinct in that they yield increased progeny in infections of cell monolayers. From the number of variant sequences it can be estimated that each infectious RNA in the population differs in two to eight mutations from the average parental sequence. Thus, passaged FMDV populations consist of a pool of variants, an observation previously made with phage Q beta (E. Domingo, D. Sabo, T. Taniguchi, and C. Weissmann, Cell 13, 735-744, 1978). The FMDV genome must be described as a fluctuating distribution of sequences due to its high mutability. This may be the basis of the extensive genetic and antigenic diversity of this virus in nature.

Animals↗
PubMed1983

Molecular cloning of cDNA from foot-and-mouth disease virus C1-Santa Pau (C-S8). Sequence of protein-VP1-coding segment.

cDNA segments copied from the RNA of foot-and-mouth disease virus (FMDV) C1-Santa Pau (isolate C-S8) have been cloned in plasmid pBR322. A 998-bp DNA fragment, that includes the region coding for capsid protein VP1, the carboxy terminus of VP3, and the amino terminus of precursor protein p52 has been sequenced. Comparison of the nucleotide sequence with those from FMDV O1K, A(10)61, A12 and C3 Indaial (Kurz et al., Nucl. Acids Res. 9 (1981) 1919-1931; Kleid et al., Science 214 (1981) 1125-1129; Boothroyd et al., Gene 17 (1982) 153-161; Makoff et al., Nucl. Acids Res. 10 (1982) 8285-8295) indicates extensive variability between the corresponding gene segments, including short insertions and deletions. Base transversions are more frequent than transitions within the VP1 coding segment, but not in the sequence coding for the amino-terminal end of p52. The nucleotide sequence divergence is reflected in variability in both the primary and the predicted higher-order structures of the encoded VP1s.

Amino Acid Sequence↗
PubMed1983

Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype.

The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/1/79 (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences.

Amino Acid Sequence↗
PubMed1980

Genetic variability of Hong Kong (H3N2) influenza viruses: spontaneous mutations and their location in the viral genome.

The genetic heterogeneity of five influenza A (H3N2) strains isolated between 1968 and 1977 has been estimated by T1-oligonucleotide fingerprinting of 32P-labeled viral RNA. Assuming that the large T1-resistant oligonucleotides represent a random sample of the viral RNA, the genetic differences observed would affect 0.3 to 10.7% of the RNA positions of the genes studied, depending on the pair of viruses considered. A smaller degree of genetic heterogeneity was observed when six coetaneous viral samples were compared. The distribution of spontaneous mutations among the viral genes was studied by fingerprinting individual RNA segments isolated either by gel electrophoresis or hybridization with plasmids containing influenza-specific DNA sequences. No statistically significant differences were detected in the distribution of mutations among the viral genes studied. The mutation frequency at the hemagglutinin RNA region coding for the HA1 subunit was found to be two times higher than that at the region encoding that HA2 subunit. Our results suggest that the antigenic variability of influenza viruses may be a consequence of a general genetic variability which effects many of the viral genes.

Antigens, Viral↗