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Genin S, Boucher CA. A superfamily of proteins involved in different secretion pathways in gram-negative bacteria: modular structure and specificity of the N-terminal domain. MOLECULAR & GENERAL GENETICS : MGG 1994; 243:112-8. [PMID: 8190064 DOI: 10.1007/bf00283883] [Citation(s) in RCA: 140] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The family of PulD proteins, which has been characterized in a wide variety of microorganisms, comprises several membrane-associated proteins essential for the transport of macromolecules across bacterial membranes. These proteins are involved in the transport of complex structures (such as phage particles, DNA) or various proteins (such as extracellular enzymes and pathogenicity determinants). Amino acid sequence analysis revealed a possible modular organisation of proteins of this superfamily, with highly conserved C-terminal domains and dissimilar N-terminal domains. In the C-terminal domain, four highly conserved regions have been found, one of them containing a remarkable common motif: (V, I)PXL(S, G)XIPXXGXLF. Structural comparisons between the N-terminal domains indicate that proteins of this superfamily can be divided into at least two subgroups, probably reflecting the existence of distinct secretion mechanisms. This implies that members of the superfamily of PulD-related proteins are independently involved in (1) the general secretory pathway, (2) a new signal-peptide-independent secretion pathway found in several bacterial pathogens, and possibly in (3) the translocation of bacteriophage particles through the bacterial cell envelope.
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Kellam P, Boucher CA, Tijnagel JM, Larder BA. Zidovudine treatment results in the selection of human immunodeficiency virus type 1 variants whose genotypes confer increasing levels of drug resistance. J Gen Virol 1994; 75 ( Pt 2):341-51. [PMID: 7509370 DOI: 10.1099/0022-1317-75-2-341] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
High level resistance to 3'-azido-3'-deoxythymidine (AZT, zidovudine or Retrovir) is conferred by the presence of four or five mutations (Met-41-->Leu; Asp-67-->Asn; Lys-70-->Arg; Thr-215-->Tyr or Phe; Lys-219-->Gln) in the human immunodeficiency virus (HIV) reverse transcriptase. The order of appearance of these five mutations in asymptomatic patients during therapy has been studied. This has enabled us to propose a model for the acquisition of zidovudine resistance mutations during the treatment of high-risk asymptomatic HIV-infected individuals. A consistent acquisition pattern of mutations at codons 41, 70 and 215 was observed in 17 individuals. Complex mixtures of HIV species containing different combinations of single and linked double resistance mutations were present early in zidovudine therapy in isolates from two patients studied in detail. From these mixtures the linked Leu-41/Tyr-215 genotype outgrew all others initially. The development of each new virus population is likely to be mediated primarily by the increase in the level of drug resistance rather than changes in the growth kinetics of the virus. This leads us to conclude that one major driving force in the outgrowth of different mutant viruses is the selective advantage conferred by higher levels of drug resistance.
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Arlat M, Van Gijsegem F, Huet JC, Pernollet JC, Boucher CA. PopA1, a protein which induces a hypersensitivity-like response on specific Petunia genotypes, is secreted via the Hrp pathway of Pseudomonas solanacearum. EMBO J 1994; 13:543-53. [PMID: 8313899 PMCID: PMC394843 DOI: 10.1002/j.1460-2075.1994.tb06292.x] [Citation(s) in RCA: 190] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
This paper describes the identification of a new class of extracellular bacterial proteins, typified by PopA1 and its derivative PopA3, which act as specific hypersensitive response (HR) elicitors. These two heat-stable proteins, with HR-like elicitor activities on tobacco (non-host plant) but without activity on tomato (host plant), have been characterized from the supernatant of the plant pathogenic bacterium Pseudomonas solanacearum strain GMI1000. These two proteins induced the same pattern of response on Petunia, as a function of the genotypes tested. popA, the structural gene for PopA1, maps outside of the hrp gene cluster but belongs to the hrp regulon. The amino acid sequence of PopA1 does not show homology to any characterized proteins. Its secretion is dependent on hrp genes and is followed by stepwise removal of the 93 amino-terminal amino acids, producing the protein PopA3. Petunia lines responsive to PopA3 and its precursors were resistant to infection by strain GMI1000, whereas non-responsive lines were sensitive, suggesting that popA could be an avirulence gene. A popA mutant remained fully pathogenic on sensitive plants, indicating that this gene is not essential for pathogenicity. While lacking PopA1, this mutant, which remained avirulent on tobacco and on resistant Petunia lines, still produced additional extracellular necrogenic compounds. On the basis of both their structural features and the biological properties of the popA mutant, PopA1 and PopA3 clearly differ from hairpins characterized in other plant pathogenic bacteria.
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Bruisten SM, Koppelman MH, Roos MT, Loeliger AE, Reiss P, Boucher CA, Huisman HG. Use of competitive polymerase chain reaction to determine HIV-1 levels in response to antiviral treatments. AIDS 1993; 7 Suppl 2:S15-20. [PMID: 8161441 DOI: 10.1097/00002030-199311002-00005] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To develop a competitive polymerase chain reaction technique with which to evaluate the usefulness of HIV-1 level as a marker of response to antiviral treatment. DESIGN HIV-1 sequences were assessed by competitive polymerase chain reaction in four subjects participating in a double-blind study of monotherapy versus combination therapy with nucleoside analogues. METHODS We inserted a mutant construct of the HIV-1 pol sequence into a commercial vector, enabling us to generate known amounts of mutant DNA and RNA for competitive polymerase chain reaction. To measure HIV-1 DNA copies in cells, the mutant DNA fragments were allowed to compete in a 10-fold dilution series with a constant amount of nucleic acid from the subject. To measure HIV-1 RNA copies in plasma, in vitro synthesized mutant RNA was added in a 10-fold dilution series to a constant amount of subject RNA and copy DNA was synthesized. DNA and copy DNA were used as the input for nested pol polymerase chain reaction. Mutant and wild-type amplimers were discriminated by size. RESULTS The competitive polymerase chain reaction technique has been validated in model experiments and can be used over a broad range (at least 6 logs) of levels. Three of the four subjects showed a decline of 1 log in proviral DNA levels in cells after beginning antiviral treatment. All four showed a decline of at least 1 log in viral RNA levels in plasma, but this decline was transient in one subject. CONCLUSION The HIV-1 sequence level is a useful marker in antiviral treatment studies.
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Boucher CA, Cammack N, Schipper P, Schuurman R, Rouse P, Wainberg MA, Cameron JM. High-level resistance to (-) enantiomeric 2'-deoxy-3'-thiacytidine in vitro is due to one amino acid substitution in the catalytic site of human immunodeficiency virus type 1 reverse transcriptase. Antimicrob Agents Chemother 1993; 37:2231-4. [PMID: 7504909 PMCID: PMC192256 DOI: 10.1128/aac.37.10.2231] [Citation(s) in RCA: 227] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Passage of human immunodeficiency virus type 1 in the presence of increasing 2'-deoxy-3'-thiacytidine (3TC) concentrations results in high-level (> 100-fold) 3TC-resistant viruses. All 3TC-resistant viruses possess a substitution at the second codon (from a methionine into an isoleucine) at position 184 within the highly conserved motif (YMDD) of human immunodeficiency virus type 1 reverse transcriptase. 3TC-resistant viruses were cross-resistant to the (-) enantiomer of the fluorinated derivative of BCH-189 but remained susceptible to 2',3'-dideoxyinosine and 2',3'-dideoxycytidine. The susceptibilities of the 3TC-resistant viruses to the (+) enantiomers of BCH-189 and the fluorinated derivative of BCH-189 demonstrate an enantiomeric specificity for viruses selected under these conditions. Introduction of an isoleucine substitution at codon 184 into a background of two known 3'-azido-3'-deoxythymidine resistance mutations (amino acids 41 and 215) restored the susceptibility of this virus to 3'-azido-3'-deoxythymidine.
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Zusman RM, Higgins J, Christensen D, Boucher CA. Bepridil improves left ventricular performance in patients with angina pectoris. J Cardiovasc Pharmacol 1993; 22:474-80. [PMID: 7504141 DOI: 10.1097/00005344-199309000-00020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Patients with coronary artery disease and angina pectoris have abnormalities of left ventricular (LV) diastolic performance. These abnormalities, which exist when the patients are at rest and not experiencing angina, are presumably secondary to abnormalities of intracellular calcium metabolism. Twenty-three patients with chronic exertional angina pectoris participated in a placebo-controlled, randomized, cross-over trial of bepridil hydrochloride. Angina frequency, nitroglycerin (NTG) consumption, and treadmill exercise capacity were assessed, and each patient underwent first-pass radionuclide cineangiography while receiving placebo or bepridil to assess LV performance. Bepridil decreased angina frequency from 8.5 +/- 0.6 to 4.4 +/- 1.5 episodes per week (p < 0.01) and NTG consumption from 7.2 +/- 2.4 to 3.6 +/- 1.5 tablets per week (p < 0.01). Total treadmill exercise time, time to onset of angina, and time to 1-mm ST segment depression increased significantly during bepridil therapy. Cardiac output (CO), stroke volume (SV), and ejection fraction (EF) increased at rest and during peak upright bicycle exercise. Peak ejection rate and peak filling rate increased, and time to peak ejection rate and time to peak filling rate decreased at rest and at peak exercise during bepridil therapy. In addition, early diastolic filling fraction increased and atrial filling volume decreased during bepridil treatment. Bepridil is effective as monotherapy for treatment of patients with exertional angina; its use is associated with increased exercise capacity and decreased angina frequency and NTG consumption as well as improved LV systolic and diastolic performance at rest and during peak exercise.
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Boucher CA, van Leeuwen R, Kellam P, Schipper P, Tijnagel J, Lange JM, Larder BA. Effects of discontinuation of zidovudine treatment on zidovudine sensitivity of human immunodeficiency virus type 1 isolates. Antimicrob Agents Chemother 1993; 37:1525-30. [PMID: 8103317 PMCID: PMC188006 DOI: 10.1128/aac.37.7.1525] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Zidovudine treatment of individuals infected with human immunodeficiency virus type 1 (HIV-1) results in HIV-1 isolates with a reduced zidovudine sensitivity in vitro. This reduction is due to mutations causing amino acid substitutions at five codons (41, 67, 70, 215, and 219) on the reverse transcriptase enzyme of HIV. HIV-1 isolates were obtained 8 to 69 weeks after therapy discontinuation from 10 patients at different stages of disease. Zidovudine sensitivity was determined by the HeLa CD4+ plaque assay. The presence of the resistance-conferring mutations was determined by using a selective polymerase chain reaction. Sensitivity could be determined for six isolate pairs: one showed a decline in the 50% inhibitory zidovudine concentration after therapy discontinuation; four pairs did not show a change. The majority of changes in the five codons in isolates from all 10 patients were the result of a relative increase in the wild-type sequence. Complete changes from mutant to the wild type were seen for only two codons in isolates from two patients. This study of isolates from a small group of individuals at different stages of disease, who had been taking zidovudine for 1 to 2 years, shows that a period of 1 year without zidovudine may be required to achieve a change from a mutant or mixed virus population to a wild-type virus population.
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Gough CL, Genin S, Lopes V, Boucher CA. Homology between the HrpO protein of Pseudomonas solanacearum and bacterial proteins implicated in a signal peptide-independent secretion mechanism. MOLECULAR & GENERAL GENETICS : MGG 1993; 239:378-92. [PMID: 8316211 DOI: 10.1007/bf00276936] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A region of approximately 22 kb of DNA defines the large hrp gene cluster of strain GMI1000 of Pseudomonas solanacearum. The majority of mutants that map to this region have lost the ability to induce disease symptoms on tomato plants and are no longer able to elicit a hypersensitive reaction (HR) on tobacco, a non-host plant. In this study we present the complementation analysis and nucleotide sequence of a 4772 bp region of this hrp gene cluster. Three complete open reading frames (ORFs) are predicted within this region. The corresponding putative proteins, HrpN, HrpO and HpaP, have predicted sizes of 357, 690 and 197 amino acids, respectively, and predicted molecular weights of 38,607, 73,990 and 21,959 dalton, respectively. HrpN and HrpO are both predicted to be hydrophobic proteins with potential membrane-spanning domains and HpaP is rich in proline residues. A mutation in hpaP (for hrp associated) does not affect the HR on tobacco or the disease on tomato plants. None of the proteins is predicted to have an N-terminal signal sequence, which would have indicated that the proteins are exported. Considerable sequence similarities were found between HrpO and eight known or predicted prokaryotic proteins: LcrD of Yersinia pestis and Y. enterocolitica, FlbF of Caulobacter crescentus, FlhA of Bacillus subtilis, MxiA and VirH of Shigella flexneri, InvA of Salmonella typhimurium and HrpC2 of Xanthomonas campestris pv. vesicatoria. These homologies suggest that certain hrp genes of phytopathogenic bacteria code for components of a secretory system, which is related to the systems for secretion of flagellar proteins, Ipa proteins of Shigella flexneri and the Yersinia Yop proteins. Furthermore, these homologous proteins have the common feature of being implicated in a distinct secretory mechanism, which does not require the cleavage of a signal peptide. The sequence similarity between HrpO and HrpC2 is particularly high (66% identity and 81% similarity) and the amino acid sequence comparison between these two proteins presented here reveals the first such sequence similarity to be shown between Hrp proteins of P. solanacearum and X. campestris. An efflux of plant electrolytes was found to be associated with the interactions between P. solanacearum and both tomato and tobacco leaves. This phenomenon may be part of the mechanism by which hrp gene products control and determine plant-bacterial interactions, since hrpO mutants induced levels of leakage which were significantly lower than those induced by the wild type on each plant.
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Zwart G, Wolfs TF, Bookelman R, Hartman S, Bakker M, Boucher CA, Kuiken C, Goudsmit J. Greater diversity of the HIV-1 V3 neutralization domain in Tanzania compared with The Netherlands: serological and genetic analysis. AIDS 1993; 7:467-74. [PMID: 8507412 DOI: 10.1097/00002030-199304000-00003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To compare variation in the HIV-1 V3 neutralization domain in Tanzania and The Netherlands. METHODS For serologic analysis, the specificity of anti-V3 antibodies (immunoglobulin G) for a panel of V3 peptides was determined in sera from 55 symptomatic HIV-1-infected Tanzanians and 51 Dutch AIDS patients. For genetic analysis, viral RNA was isolated from 15 of the Tanzanian sera and six of the Dutch sera. The V3 encoding region was reverse-transcribed, polymerase chain reaction-amplified and bacterially cloned, and sequences were determined over a stretch of at least 207 nucleotides. RESULTS Thirty-five per cent of the Tanzanian sera, versus 2% of the Dutch sera, showed the highest reactivity to a V3 sequence of Zairian origin (RKSIHVGPGQAFYATG). Twenty-nine per cent of the Tanzanian sera, versus 82% of the Dutch sera, showed the highest reactivity to V3 sequences of US/European origin (RKSIXIGPGRAFYTTG; X = H, P or N). The Tanzanian RNA sequences showed greater diversity (mean distance, 19%) than the Dutch RNA sequences (10%). The measured anti-V3 specificities of the Tanzanian sera did not match accurately with the V3 sequences recovered from these sera. However, reactivity to the Zairian V3 peptide was associated with the sequence GPGQ, found in the centre of the V3 in 50% of the Tanzanian sequences. Sera from both countries that showed similar reactivities to the peptide panel contained RNA sequences that were relatively distant. CONCLUSIONS The diversity of the HIV-1 population in Tanzania is much greater than that in The Netherlands. An indication of the HIV-1 V3 variation in a particular geographic region can be obtained by serological methods, but sequence analysis should not be omitted.
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Lange JM, Teeuwsen VJ, Boucher CA, Vahlne A, Barin F, Tjong-A-Hung S, Dekker J, Parkhede U, de Wolf F, Goudsmit J. Antigenic variation of the dominant gp41 epitope in Africa. AIDS 1993; 7:461-6. [PMID: 8507411 DOI: 10.1097/00002030-199304000-00002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVE To determine the value of (combinations of) synthetic peptides representing immunodominant sites on HIV-1/HIV-2 transmembrane proteins for the detection and discrimination between HIV-1 and HIV-2 infection in various populations. DESIGN AND METHODS Two 24-mer synthetic peptides derived from immunodominant sites on the HIV-1 and HIV-2 transmembrane proteins were used separately, in combination (env 1/2), and in combination with recombinant p24 (p24/env) in enzyme-linked immunosorbent assays. RESULTS Positive reactions with env-1 were found in 150 out of 150 (100%) samples from Dutch AIDS patients, 60 out of 60 (100%) samples from Dutch homosexual men obtained 1 year after HIV-1-antibody seroconversion, 29 out of 30 (96.7%) samples from these men obtained at the time of HIV-1-antibody seroconversion, 40 out of 41 (97.6%) samples from East Africans with AIDS-related symptoms, and three out of 29 (10.3%) samples from West Africans with HIV-2 infection (including a sample from an individual infected with both HIV-1 and HIV-2). Positive reactions with env-2 in these study populations were 11 out of 150 (7.3%), nine out of 60 (15%), none out of 30 (0%), 25 out of 41 (60.9%) and 29 out of 29 (100%), respectively. In the samples with dual reactivity, true versus cross-reactivity could generally be differentiated on the basis of large differences in optical density values in the respective assays. All samples reacted positively with p24/env; 308 out of 310 (99.3%) were positive in the env 1/2 assay. Four East African samples that had negative or only weakly positive reactions with env-1 showed a noticeably stronger reaction with variant peptides derived from Central African isolate sequences. In all samples from HIV-1-infected Dutch homosexual men, the strongest signal was detected using the env-1 peptide sequence, which is derived from European and American isolates. CONCLUSIONS Small peptide antigens may permit the detection of strain-specific antibodies, allowing serological characterization of HIV isolates.
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Björling E, Boucher CA, Samuelsson A, Wolfs TF, Utter G, Norrby E, Chiodi F. Two highly antigenic sites in the human immunodeficiency virus type 1 reverse transcriptase. J Clin Microbiol 1993; 31:588-92. [PMID: 7681439 PMCID: PMC262825 DOI: 10.1128/jcm.31.3.588-592.1993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Antibodies to human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) are found in the serum of the majority of infected individuals, and inhibition of RT polymerase activity by HIV-1-positive sera can be demonstrated in vitro. The binding sites of human antibodies on the protein have not yet been identified. We synthesized overlapping peptides covering the entire RT protein of HIV-1 and used them in an enzyme-linked immunosorbent assay system to map the reactivities of HIV-1 and HIV-2 antibody-positive sera. Two highly antigenic regions were identified by both HIV serotypes. One region was found in the central part of the RT protein (amino acids 261 to 280) and another was found at the carboxy terminus in the RNase H portion of RT (amino acids 517 to 536). Comparison of the serological results with the crystal structure of the RT revealed that the antigenic region in the RNase H portion is located at the surface of the protein. The other antibody-binding site (amino acids 261 to 280) was located in the "thumb" region of the polymerase domain of RT. Polyclonal antibodies to either of the antibody-binding sites do not affect the polymerase activity of the RT protein.
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Travin MI, Boucher CA, Newell JB, LaRaia PJ, Flores AR, Eagle KA. Variables associated with a poor prognosis in patients with an ischemic thallium-201 exercise test. Am Heart J 1993; 125:335-44. [PMID: 8427125 DOI: 10.1016/0002-8703(93)90009-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To determine the exercise workload, ECG, and thallium-201 image parameters that are most closely associated with a poor prognosis from ischemic heart disease, the test results of 268 patients were reviewed. Only patients with unequivocal thallium-201 redistribution were selected. A multivariate analysis was performed to find the variables that were most strongly associated with the outcomes of coronary revascularization, myocardial infarction, and cardiac death during a follow-up period of 25 +/- 19 months. Patients who underwent early elective revascularization had poorer exercise tolerance and more thallium image abnormalities than those with no events. In the remaining patients myocardial infarction was most closely related to the extent and severity of thallium ischemia (p = 0.0086), whereas cardiac death was associated with abnormal thallium lung uptake (p = 0.0082) and an inability to exercise to 9.6 MET (p = 0.0144). Thus unlike myocardial infarction, cardiac death is best predicted by variables that reflect poor left ventricular function rather than those that indicate ischemia.
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Okada RD, Murphy JH, Boucher CA, Pohost GM, Strauss HW, Johnson G, Daggett WM. Relationship between septal perfusion, viability, and motion before and after coronary artery bypass surgery. Am Heart J 1992; 124:1190-5. [PMID: 1442485 DOI: 10.1016/0002-8703(92)90399-g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The etiology of abnormal interventricular septal motion occurring after open-heart surgery using cardiopulmonary bypass has not been clarified. Intraoperative ischemic septal injury has been proposed as one explanation for this finding. To examine this possibility, resting septal perfusion and viability were studied using rest and redistribution thallium-201 scintigraphy in 16 patients before and after coronary artery bypass surgery. The results were compared with septal motion on preoperative and postoperative resting gated blood pool scans. Preoperatively, septal thallium uptake was normal in 10 of 16 patients, and septal motion was normal in 14 of 16. Postoperatively, septal thallium uptake was normal in 11 of 16 patients, while septal motion was abnormal in all. Thus abnormal postoperative septal motion is usually associated with normal septal perfusion and viability on thallium scans and therefore is not the result of septal ischemic injury in a majority of patients.
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Boucher CA, Lange JM, Miedema FF, Weverling GJ, Koot M, Mulder JW, Goudsmit J, Kellam P, Larder BA, Tersmette M. HIV-1 biological phenotype and the development of zidovudine resistance in relation to disease progression in asymptomatic individuals during treatment. AIDS 1992; 6:1259-64. [PMID: 1282015 DOI: 10.1097/00002030-199211000-00003] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE To determine which parameters are associated with clinical progression during zidovudine treatment of asymptomatic HIV-1-infected individuals. METHODS Twenty-four initially asymptomatic HIV-1-infected individuals were treated with zidovudine and followed until the development of AIDS or for approximately 3 years. HIV-1 phenotype was determined by cocultivation of patient cells with donor lymphocytes, and by a new assay of direct cocultivation with MT-2 cells. Specific mutations in the HIV-1 reverse transcriptase (RT) gene conferring resistance to zidovudine were detected using a selective polymerase chain reaction. RESULTS Progression to AIDS was more rapid in individuals harbouring syncytium-inducing (SI) viral isolates or showing a conversion from non-syncytium-inducing (NSI) to SI viral isolates. One out of 20 patients who spent a total of 559 months harbouring an NSI phenotype progressed to AIDS, whereas eight out of 12 patients who spent a total of 223 months harbouring an SI phenotype progressed to AIDS (P < 0.001). There was no significant difference between SI and non-SI isolates in the frequency of five mutations causing zidovudine resistance. However, all SI isolates obtained after 2 years of treatment contained mutations in codons 41 and 215 of the RT gene, whereas only five out of 11 (45%) NSI isolates obtained at that time had this combination of mutations. CONCLUSIONS Conversion to the SI phenotype cannot be prevented by zidovudine treatment. The presence or appearance of an SI virus heralded disease progression in zidovudine-treated individuals. Further research is required to investigate the relationship between virus phenotype and development of zidovudine resistance.
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Burstein S, Semigran MJ, Dec GW, Boucher CA, Fifer MA. Positive inotropic and lusitropic effects of intravenous flosequinan in patients with heart failure. J Am Coll Cardiol 1992; 20:822-9. [PMID: 1527293 DOI: 10.1016/0735-1097(92)90179-q] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVES This study was designed to assess the direct effects of flosequinan on myocardial function. BACKGROUND Flosequinan has been shown to improve symptoms and exercise tolerance in patients with heart failure. Although previous studies have established that flosequinan is a vasodilator, it is not known to what extent direct actions of the drug on myocardial contractility or diastolic properties contribute to its beneficial hemodynamic effects. METHODS Nitroprusside and intravenous flosequinan were administered sequentially to 18 patients with severe heart failure (New York Heart Association functional class III or IV, left ventricular ejection fraction 0.14 +/- 0.02). Micromanometer left ventricular pressure and radionuclide volume data were combined to construct pressure-volume loops during 1) a baseline period, 2) nitroprusside infusion, 3) a second baseline period, and 4) flosequinan infusion. RESULTS The peak rate of left ventricular pressure development increased from 899 +/- 84 to 1,070 +/- 94 mm Hg/s (p less than 0.05) with flosequinan. The baseline left ventricular end-systolic pressure-volume relation was constructed in 15 patients from the two baseline pressure-volume loops and from that obtained during afterload manipulation with nitroprusside. During flosequinan administration, the relation between end-systolic pressure and volume was shifted upward and leftward, indicating enhanced contractility, in 14 of 15 patients (p less than 0.001). The maximal rate of decrease in left ventricular pressure during isovolumetric relaxation increased in magnitude with flosequinan from 882 +/- 63 to 1,026 +/- 68 mm Hg/s (p less than 0.05). CONCLUSIONS These results indicate that intravenous flosequinan has positive inotropic and lusitropic effects in patients with heart failure. Further studies are needed to assess the direct myocardial effects of oral flosequinan.
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Genin S, Gough CL, Zischek C, Boucher CA. Evidence that the hrpB gene encodes a positive regulator of pathogenicity genes from Pseudomonas solanacearum. Mol Microbiol 1992; 6:3065-76. [PMID: 1479894 DOI: 10.1111/j.1365-2958.1992.tb01764.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The hrp gene cluster of Pseudomonas solanacearum GMI1000 strain encodes functions that are essential for pathogenicity on tomato and for the elicitation of the hypersensitive response on tobacco. In this study, we present the nucleotide sequence of one of the hrp genes (hrpB) located at the left-hand end of the cluster and we show that hrpB encodes a positive regulator controlling the expression of hrp genes. hrpB has a coding capacity for a 477-amino-acid polypeptide, which shows significant similarity to several prokaryotic transcriptional activators including the AraC protein of Escherichia coli, the XylS protein of Pseudomonas putida and the VirF protein of Yersinia enterocolitica. The predicted hrpB gene product belongs to a family of bacterial regulators different from the previously described HrpS protein of the hrp gene cluster of Pseudomonas syringae pv. phaseolicola. Genetic evidence demonstrates that the hrpB gene product acts as a positive regulator of the expression in minimal medium of all but one of the putative transcription units of the hrp gene cluster and also controls the expression of genes located outside this cluster. We also show in this paper that the transcription of hrpB is induced in minimal medium and is partly autoregulated.
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Zusman RM, Christensen DM, Higgins J, Boucher CA. Comparison of the cardiac and hemodynamic effects of lisinopril and atenolol in patients with hypertension: therapeutic implications. J Cardiovasc Pharmacol 1992; 20:216-22. [PMID: 1381012 DOI: 10.1097/00005344-199208000-00006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The antihypertensive and hemodynamic effects of lisinopril and atenolol were evaluated in 21 patients with mild-to-moderate essential hypertension. Left ventricular systolic and diastolic performances were assessed prior to and following treatment by first-pass radionuclide cineangiography at rest and during peak upright bicycle exercise. Both lisinopril and atenolol treatment significantly reduced the blood pressure. Lisinopril therapy was associated with a reduction in systemic vascular resistance and left ventricular end-diastolic and end-systolic volumes but no change in stroke volume, cardiac output, peak ejection rate, peak filling rate, time to peak ejection rate, or time to peak filling rate. In contrast, atenolol therapy was associated with an increase in end-diastolic volume and stroke volume but no change in cardiac output; the left ventricular peak ejection and peak filling rates were decreased by atenolol treatment. Although both lisinopril and atenolol each significantly reduced the blood pressure, lisinopril had no effect on left ventricular systolic or diastolic performance; in contrast, atenolol decreased both systolic and diastolic parameters of ventricular performance. Left ventricular function may be affected in significantly different ways despite apparent similarities in blood pressure control in patients who respond to angiotensin converting enzyme inhibition or beta-adrenergic receptor blockade. Differences in hemodynamic response to an antihypertensive agent may be important in the selection of a drug for the treatment of subsets of patients with cardiac function abnormalities.
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Semigran MJ, Aroney CN, Herrmann HC, Dec GW, Boucher CA, Fifer MA. Effects of atrial natriuretic peptide on myocardial contractile and diastolic function in patients with heart failure. J Am Coll Cardiol 1992; 20:98-106. [PMID: 1535081 DOI: 10.1016/0735-1097(92)90144-c] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Atrial natriuretic peptide alters left ventricular performance in patients with heart failure. To assess the direct effects of this hormone on myocardial function, its actions were compared with those of the pure vasodilator nitroprusside in 10 patients with heart failure. Simultaneous left ventricular micromanometer pressure and radionuclide volume were obtained during a baseline period, during nitroprusside infusion, during a second baseline period and during atrial natriuretic peptide infusion. The baseline end-systolic pressure-volume relation was generated in nine patients from pressure-volume loops obtained during the two baseline periods and during afterload reduction with nitroprusside. Mean arterial pressure decreased with atrial natriuretic peptide (89 +/- 3 to 80 +/- 2 mm Hg, p less than 0.05) and by a greater amount with nitroprusside (90 +/- 4 to 73 +/- 3 mm Hg, p less than 0.05). Left ventricular end-diastolic pressure also decreased with atrial natriuretic peptide (24 +/- 2 to 16 +/- 3 mm Hg, p less than 0.05) and by a greater amount with nitroprusside (24 +/- 2 to 13 +/- 3 mm Hg, p less than 0.05). Cardiac index increased during infusion of each agent from 2.0 +/- 0.2 to 2.4 +/- 0.2 liters/min per m2 (p less than 0.01). Heart rate increased slightly with nitroprusside but did not change with atrial natriuretic peptide. Peak positive first derivative of left ventricular pressure (dP/dt), ejection fraction and stroke work index were unchanged by either agent. The relation between end-systolic pressure and volume during atrial natriuretic peptide infusion was shifted slightly leftward from the baseline value in four patients, slightly rightward in four and not at all in one patient, indicating no consistent inotropic effect.(ABSTRACT TRUNCATED AT 250 WORDS)
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Coley CM, Field TS, Abraham SA, Boucher CA, Eagle KA. Usefulness of dipyridamole-thallium scanning for preoperative evaluation of cardiac risk for nonvascular surgery. Am J Cardiol 1992; 69:1280-5. [PMID: 1585860 DOI: 10.1016/0002-9149(92)91221-o] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The ability to stratify cardiac risk before nonvascular surgery using clinical markers and dipyridamole-thallium scanning (DTS) was assessed for patients with known or suspected coronary artery disease unable to exercise. Of 100 consecutively studied patients who proceeded to nonvascular surgery, 9 (9%) experienced greater than or equal to 1 perioperative cardiac ischemic event, including death in 2 patients (2%) and nonfatal myocardial infarction in 2 (2%). Logistic regression identified 2 clinical predictors (age greater than 70 years and history of heart failure), and 1 DTS (thallium redistribution) predictor of events. Of 45 patients with neither clinical variable, none (0%; 95% confidence intervals [CI] 0 to 8%) had events. Of 55 patients with greater than or equal to 1 clinical marker, 9 (16.4%; 95% CI 7 to 26%) had events. Within this subgroup, 1 of 31 patients (3.2%; 95% CI 0 to 16%) without thallium redistribution had events compared with 8 of 24 (33.3%; 95% CI 14 to 52%) with redistribution. An algorithm combining 5 independent clinical and 2 DTS predictors, derived previously in vascular surgery patients, was validated in the 100 nonvascular surgery patients. It is concluded that preoperative planar DTS is most useful to stratify selected nonvascular surgery patients at intermediate or high risk by clinical assessment. However, for almost half of those patients with known or suspected coronary artery disease, DTS may be unnecessary because of sufficiently low predictive value based on simple clinical descriptors.
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Zusman RM, Christensen DM, Higgins J, Boucher CA. Effects of antianginal therapy on left ventricular systolic and diastolic performance: comparison of the response to bepridil, propranolol, and diltiazem. Am J Cardiol 1992; 69:25D-30D. [PMID: 1553888 DOI: 10.1016/0002-9149(92)90955-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Abnormalities of left ventricular (LV) systolic performance develop during exercise in patients with coronary artery disease (CAD) as a result of ischemia-induced regional wall motion abnormalities. Like patients with hypertension and those with hypertrophic cardiomyopathy, patients with CAD display abnormalities of LV diastolic performance under basal conditions in the absence of ischemia. The purpose of these studies was to compare the effects of bepridil versus those of propranolol or diltiazem in patients with exertional angina pectoris. LV systolic and diastolic performance were assessed at rest and during peak upright bicycle exercise by first-pass radionuclide ventriculography. Compared with propranolol, bepridil increased exercise capacity, cardiac output, and stroke volume and decreased systemic vascular resistance. Compared with diltiazem, bepridil increased exercise capacity, peak filling rate, and early diastolic filling fraction and decreased systemic vascular resistance, heart rate, time to peak filling rate, and atrial filling volume. Bepridil therapy is associated with improved exercise capacity and decreased anginal frequency and nitroglycerin consumption. In addition, its use is accompanied by favorable changes in LV systolic and diastolic function at rest and during exercise. These changes are consistent with benefits resulting from resolution of myocardial ischemia as well as from positive lusitropic effects of bepridil on the ventricular myocardium.
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Kellam P, Boucher CA, Larder BA. Fifth mutation in human immunodeficiency virus type 1 reverse transcriptase contributes to the development of high-level resistance to zidovudine. Proc Natl Acad Sci U S A 1992; 89:1934-8. [PMID: 1371886 PMCID: PMC48568 DOI: 10.1073/pnas.89.5.1934] [Citation(s) in RCA: 307] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is recognized that high-level resistance to 3'-azido-3'-deoxythymidine (AZT, zidovudine, or Retrovir) is conferred by the presence of four mutations in the human immunodeficiency virus (HIV) reverse transcriptase [RT; deoxynucleoside-triphosphate:DNA deoxynucleotidyltransferase (RNA-directed), EC 2.7.7.49] coding sequence. However, a number of clinical isolates have been observed that exhibit high-level resistance but contain only three of the four identified mutations (Asn-67, Arg-70, and Tyr-215). Construction of a molecular clone with this genotype gave rise to only a partially resistant virus, raising the possibility that an additional mutation existed in some clinical isolates. Using an HIV marker rescue system, we have mapped and identified a fifth mutation conferring resistance to zidovudine, namely, methionine to leucine at codon 41 of HIV RT. An infectious molecular clone containing this mutation together with three previously identified mutations in the RT coding sequence yielded highly resistant HIV after transfection of T cells. Direct detection of the fifth mutation in DNA samples from cocultured peripheral blood lymphocytes by the PCR revealed that it occurred relatively early in the development of zidovudine resistance. However, this mutation was only detected after the appearance of the codon 215 change in the RT coding sequence. Identification of this mutation in addition to the other known mutations conferring resistance enables rapid and direct correlation between an RT genotype and sensitivity of the virus.
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Zusman RM, Christensen DM, Higgins J, Boucher CA. Effects of fosinopril on cardiac function in patients with hypertension. Radionuclide assessment of left ventricular systolic and diastolic performance. Am J Hypertens 1992; 5:219-23. [PMID: 1534664 DOI: 10.1093/ajh/5.4.219] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Numerous pharmacologic agents are capable of lowering the blood pressure of hypertensive patients; however, each drug has a characteristic side effect profile and effect on cardiac performance. In this study, the hemodynamic effects of the angiotensin converting enzyme inhibitor fosinopril were assessed at rest and at peak upright bicycle exercise by first-pass radionuclide cineangiography in 12 patients with essential hypertension. Fosinopril reduced blood pressure at rest in the seated position from 152/101 to 131/85 mm Hg (P less than .01) and at peak exercise from 206/103 to 184/91 mm Hg (P less than .01). Fosinopril therapy was associated with an increase in stroke volume and cardiac output and a decrease in systemic vascular resistance at rest and during peak exercise. Both peak ejection rate and peak filling rate increased significantly at rest during fosinopril therapy. The unique cardiotropic response to fosinopril may reflect its effects on the myocardial renin-angiotensin system, and suggests that this agent may offer a therapeutic advantage compared with other angiotensin converting enzyme inhibitors.
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Boucher CA, Lange JM. HIV-1 sensitivity to zidovudine and clinical outcome. Lancet 1992; 339:626. [PMID: 1347137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
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Boucher CA. Clinical significance of zidovudine-resistant human immunodeficiency viruses. RESEARCH IN VIROLOGY 1992; 143:134-6. [PMID: 1594797 DOI: 10.1016/s0923-2516(06)80098-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Arlat M, Gough CL, Zischek C, Barberis PA, Trigalet A, Boucher CA. Transcriptional organization and expression of the large hrp gene cluster of Pseudomonas solanacearum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1992; 5:187-93. [PMID: 1617200 DOI: 10.1094/mpmi-5-187] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cloning and localized mutagenesis of the larger cluster of hrp genes of Pseudomonas solanacearum strain GMI1000 allowed the definition of the borders of this cluster, which now extends about 2 kb to the left of the insert of the previously described plasmid pVir2 (Boucher et al. 1987, J. Bacteriol. 169:5626-5632). The size of the cluster has also been expanded 3 kb to the right to include a region previously described as dsp; our present data demonstrate that insertions occurring in these 3 kb lead to leaky mutations affecting both pathogenicity on tomato and ability to induce the hypersensitive response (HR) on tobacco. Therefore, the size of the entire hrp gene cluster is estimated to be about 22 kb. The use of transposon Tn5-B20, which promotes transcriptional gene fusions, allowed us to demonstrate that the hrp gene cluster is organized in a minimum of six transcriptional units, which are transcribed when the culture is grown in minimal medium but are repressed during growth in rich medium or in the presence of peptone or Casamino Acids. The level of expression in minimal medium is modulated by the carbon source provided; pyruvate is the best inducer. Under these conditions the level of expression observed in vitro appears to be representative of the actual expression observed in planta.
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