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J E Hansen

Publications and source records attributed to J E Hansen.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Long-term effect of 131I therapy of multinodular non-toxic goiter].

The aim of this study was to investigate the long term effect of 131I treatment on thyroid function and size in patients with non-toxic multinodular goitre. The subjects were 69 consecutive patients with multinodular non-toxic goitre selected for 131I treatment and followed for a minimum of 12 months. Outcome measures were standard thyroid function variables and ultrasonically determined thyroid volume before and after treatment. Fifty-nine patients were treated with a single dose of 131I, 12 with two doses, and one with four doses. In 45 patients treated with one dose who remained euthyroid the median thyroid volume was reduced from 73 (interquartile range 50-106) ml to 29 (interquartile range 23-48) ml at 24 months. The median reduction was 40 (22-48) ml, half of which occurred within three months. Patients treated with two doses as well as those developing hypo- or hyper-thyroidism also had a significant reduction in thyroid volume. Eleven patients developed hypothyroidism (cumulative five year risk 22%). Side effects were few. In conclusion we find that 131I treatment of multinodular non-toxic goitre is an attractive alternative to surgery.

Adult↗
PubMed1994

Fluorescence detection of conformational changes in GroEL induced by thermal switching and nucleotide binding.

GroEL assists other proteins to fold in vivo, usually requiring Mg2+ and ATP to function. Electron micrographs reveal that ATP binding induces a conformational change in this protein. Previously we have suggested that a thermally induced conformational change in GroEL results in the switching between enhanced and arrested reactivation of bacterial glucose-6-phosphate dehydrogenase. This thermal switching occurs over a narrow temperature range (25-30 degrees C). Recently it has aslo been reported that the binding affinity of the P22 tail spike polypeptide to GroEL changes abruptly over this same temperature range. To determine whether these conformational changes occur in GroEL in solution in absence of folding intermediates, the protein was stoichiometrically labeled with AEDANS (N-(acetylaminoacyl)-5-naphthalene-1-sulfonic acid), a fluorescent label whose emission is environment-sensitive. By measuring changes in the fluorescence Stokes shift we have detected two thermally induced conformational changes between 25 and 30 degrees C. The first change occurs between 25 and 26 degrees C, resulting in less than a 1-nm shift in the fluorescence. The second conformational change occurs between 27 and 30 degrees C, resulting in a 3-nm fluorescence shift. The conformational change induced by ATP binding also results in a 3-nm shift in fluorescence. Our data provide a correlation between functional change and structural change in GroEL.

Adenosine Triphosphate↗
PubMed1994

Identification of three N-linked glycans in the V4-V5 region of HIV-1 gp 120, dispensable for CD4-binding and fusion activity of gp 120.

Site-directed mutagenesis was used to study the biological significance of three N-linked glycans (linked to Asn406, Asn448, and Asn463), situated in the CD4-binding region of gp120. Mutagenesis was carried out in a phage M13 system, and the mutated env genes were inserted into recombinant vaccinia virus (r-vaccinia virus). To evaluate if the level of expression affected the biological phenotype of mutant gp120, we expressed the envelope glycoproteins using either a weak (7.5 K) or a strong (11 K) promoter of vaccinia virus. The expression of mutated env proteins was analyzed after infecting CD4-expressing HeLa cells with the r-vaccinia virus, by monitoring the ability of the infected cells to generate CD4-dependent syncytia. Env gene products lacking all three glycans as well as env gene products lacking different permutations of one or two glycans were analyzed. All mutated gp120 species had the expected electrophoretical mobility as anticipated from elimination of one, two, and three N-linked glycans, respectively. Moreover, all mutant env gene products demonstrated the same capacity to induce formation of syncytia, irrespective of using the weak or strong promoter for expression. These data indicate that the three N-linked glycans studied are dispensable for HIV env gene products to function in CD4-binding and the subsequent fusion step.

Amino Acid Sequence↗
PubMed1994

Identification of an N-linked glycan in the V1-loop of HIV-1 gp120 influencing neutralization by anti-V3 antibodies and soluble CD4.

Glycosylation is necessary for HIV-1 gp120 to attain a functional conformation, and individual N-linked glycans of gp120 are important, but not essential, for replication of HIV-1 in cell culture. We have constructed a mutant HIV-1 infectious clone lacking a signal for N-linked glycosylation in the V1-loop of HIV-1 gp120. Lack of an N-linked glycan was verified by a mobility enhancement of mutant gp120 in SDS-gel electrophoresis. The mutated virus showed no differences in either gp120 content per infectious unit or infectivity, indicating that the N-linked glycan was neither essential nor affecting viral infectivity in cell culture. We found that the mutated virus lacking an N-linked glycan in the V1-loop of gp120 was more resistant to neutralization by monoclonal antibodies to the V3-loop and neutralization by soluble recombinant CD4 (sCD4). Both viruses were equally well neutralized by ConA and a conformation dependent human antibody IAM-2G12. This suggests that the N-linked glycan in the V1-loop modulates the three-dimensional conformation of gp120, without changing the overall functional integrity of the molecule.

Amino Acid Sequence↗
PubMed1994

Antibody to HIV-1 Tat protein inhibits the replication of virus in culture.

The HIV-1 transactivator protein Tat is essential for viral replication. Tat is released from infected cells and can be taken up and transactivate HIV-LTR in LTR-CAT transfected cell lines. The present study shows that the addition of monoclonal antibody to Tat in IIIB and MN-infected cultures reduces the HIV antigen production in a concentration dependent manner. These data suggest that external Tat might be important in the replication of HIV, exerting the effect in a paracrine fashion. Using 1 microgram/ml of anti-Tat antibody resulted in a decline of HIV antigen production to 33% and 45% of controls in IIIB and MN infected H9 cells, respectively. A time course experiment showed progressively increased inhibition of replication during 7 days of exposure to anti-Tat antibody, which could be due to increasing Tat concentration. The inhibitory effect of anti-Tat antibodies on the replication of HIV could play an important regulatory role during infection in vivo.

Antibodies, Monoclonal↗
PubMed1994

HIV-1 infection of in vitro cultured human monocytes: early events and influence of anti HIV-1 antibodies.

To characterize the role of the humoral immune response on HIV-1 infection of monocytes and macrophages (M phi s) we examined the susceptibility of in vitro cultured monocyte/M phi s to various HIV-1 isolates and the influence of heterologous and particularly autologous anti HIV-1 sera on this infection. Depending on the period of in vitro cultivation and the virus isolate used different patterns of susceptibility were detected. One week old monocyte/M phi s were highly susceptible to HIV-1 infection, in contrast to monocyte/M phi s cultured 4 weeks. The infection by virus isolated immediately after seroconversion lead to persistent infection with high level of antigen production in contrast to infection by homologous virus isolated later. MAb against the V3-IIIB loop and sCD4 inhibited the infection of monocyte/M phi s in a dose dependent manner, indicating that infection requires binding to CD4 and that post binding events may be common to the infection of lymphocytes. Anti HIV-1 sera showed neutralizing activity against heterologous and even autologous escape virus. This finding, together with the observation that monocytes and M phi s are infected in vivo, suggests that protection against HIV-1 infection of monocytes and M phi s in vivo may not be obtainable by the humoral immune response alone.

Cells, Cultured↗
PubMed1994

Tumour necrosis factor and eicosanoid production from monocytes exposed to HIV in vitro.

We investigated the hypothesis that exposure of monocytes to human immunodeficiency virus (HIV) augments production of proinflammatory mediators. The production of tumour necrosis factor alpha (TNF-alpha) and the eicosanoids PGE2 and LTB4 from human monocytes was evaluated after exposure to two strains of HIV (SSI-002 or HIV-1IIIB). After 16 h incubation with low doses of SSI-002, lipopolysaccharide-stimulated TNF-alpha production was enhanced 70-85% while PGE2 production was decreased. Heat-inactivated virus failed to alter the production of these mediators. Higher viral doses tended to decrease TNF-alpha and PGE2 production concomitantly, but this might be due to toxicity. HIV-1IIIB had no effect on either TNF-alpha or PGE2 production. Calcium ionophore-stimulated LTB4 production was doubled by HIV-1IIIB, but significantly decreased by SSI-002. Three or seven days after exposure to both HIV strains, increased PGE2 production was found. In conclusion, HIV only modestly altered the production of mediators from monocytes. The effects were strain-specific. In most experiments a second stimulus was required to demonstrate differences.

Dinoprostone↗
PubMed1994

Neutralization epitopes on HIV pseudotyped with HTLV-I: conservation of carbohydrate epitopes.

One mechanism for expanding the cellular tropism of human immunodeficiency virus (HIV) in vitro is through formation of phenotypically mixed particles (pseudotypes) with human T lymphotropic virus type I (HTLV-I). In this study we found that pseudotypes allow penetration of HIV particles into CD4-negative cells, previously nonsusceptible to HIV infection. The infection of CD4-negative cells with pseudotypes could be blocked with anti-HTLV-I serum but failed to be significantly inhibited with anti-HIV serum or a V3-neutralizing anti-gp120 monoclonal antibody. This may represent a possibility for pseudotypes to escape neutralization by the immune system in vivo. Previous reports have suggested that carbohydrate structures may be conserved neutralization epitopes on retroviruses. In this study, the neutralizing capacity of lectins and anti-carbohydrate monoclonal antibodies was found to block infection by cell-free pseudotypes in CD4-negative cells. We suggest that although viral cofactors might expand the tropism of HIV in vivo, HIV and HTLV-I seem to induce common carbohydrate neutralization epitopes.

Antibodies, Monoclonal↗
PubMed1993

Thermal switching between enhanced and arrested reactivation of bacterial glucose-6-phosphate dehydrogenase assisted by GroEL in the absence of ATP.

Facilitation of protein folding by GroEL usually requires involvement of GroES and ATP. In their absence nascent proteins tend to be arrested on GroEL or, if released, fail to show enhancement of reactivation yield relative to that observed without the chaperonin. In contrast, the yield of reactivation of glucose-6-phosphate dehydrogenase (Glu-6-PDH) from Leuconostoc mesenteroides at 20 degrees C is increased 2-3-fold (to over 80%) by GroEL alone. ATP greatly enhances the rate of GroEL-assisted reactivation and slightly increases its yield to 90%. The efficiency of the GroEL-assisted reactivation of Glu-6-PDH is strongly dependent on temperature. A switch from enhanced to fully arrested reactivation occurs over a narrow temperature range from 25 to 30 degrees C in the presence of GroEL when ATP is absent. At physiological temperature therefore, reactivation is fully arrested by GroEL if ATP is absent and in its presence the protein is released in a form not committed to correct folding. The data shows that the committing step in Glu-6-PDH refolding occurs while the nascent protein is bound to GroEL, a step which is temperature-sensitive. The extreme temperature sensitivity of this step indicates a sharp structural transition in GroEL.

Adenosine Triphosphate↗
PubMed1993

Screening for inhibitors of HIV gp120-CD4 binding using an enzyme-linked immunoabsorbent assay.

Binding of the HIV-1 major viral surface glycoprotein, gp120, to the major cell receptor, CD4, is essential for HIV infection of the target cell and syncytium formation. An enzyme-linked immunoassay using solid phase CD4 was used to quantitate the binding of HIV-1 gp120 to CD4, and to assess the activity and mechanism of action of putative inhibitors of that reaction. Monoclonal antibodies to the gp120 binding site on CD4 (e.g., Leu3a) blocked gp120 binding, while monoclonal antibodies to other portions of CD4 (e.g. OKT4) did not. Both aurintricarboxylic acid and sulfonated polysaccharides (e.g., dextran sulfate) blocked CD4-gp120 interactions by binding to the CD4 component. Human polyclonal antibodies to gp120 also blocked gp120-CD4 binding, but none of the monoclonal antibodies tested (including several with neutralizing activity) were effective. In contrast, several lectins (including mannose binding protein) bound to gp120 and blocked CD4-gp120 interactions. Enzymatic deglycosylation of gp120 only minimally affected its CD4 binding capacity, while non-glycosylated gp120 (produced in Escherichia coli)-bound CD4 about 10-fold less well than fully-glycosylated material. The results demonstrate that this assay system can be used to measure the activity of inhibitors of CD4-gp120 binding, and to determine the mechanism of action of those inhibitors.

Antiviral Agents↗
PubMed1993

Neutralizing antibody response during human immunodeficiency virus type 1 infection: type and group specificity and viral escape.

The paradox that group-specific neutralizing antibodies (NA) exist in the majority of human immunodeficiency virus type 1 (HIV-1)-infected patients, whereas the NA response against autologous HIV-1 virus isolates is highly type-specific, motivated us to study the type- and group-specific NA responses generated upon presentation of escape virus, and the viral epitopes involved in the escape. Patients with demonstrable escape virus all developed group-specific NA, which were detectable after a delay and disappeared prior to disease development. The sera tested inhibited the binding of recombinant soluble gp120IIIB to cell-associated CD4, but group-specific virus neutralization required binding of NA to HIV-1 prior to viral attachment to target cells. Consecutive escape virus isolates were tested for sensitivity to neutralization by heterologous sera. Only minor differences were demonstrated, suggesting that the majority of the change in neutralization sensitivity is driven by the selective pressure of type-specific NA. Furthermore, no differences were observed in sensitivity to neutralization by anti-carbohydrate neutralizing monoclonal antibodies or the lectin concanavalin A, indicating a conserved nature of certain carbohydrate neutralization epitopes during escape. Finally the V3 sequence of three sets of consecutive virus isolates were analysed revealing amino acid mutations in V3 sequences of all escape virus isolates. The biological significance of these variations was confirmed further by the demonstration of changes in sensitivity to neutralization by anti-V3 monoclonal antibodies. These results strongly suggest a participation of the NA response against the V3 loop in the immunoselection of escape virus.

Amino Acid Sequence↗
PubMed1993

A statistical approach for assessment of bronchodilator responsiveness in pulmonary function testing.

OBJECTIVE: Because published criteria for bronchodilator responsiveness are based on population variability and compare only the single best measures before and after intervention, we hypothesized that the variability of the FEV1 and FEV3 of each patient would better determine that patient's responsiveness. DESIGN AND INTERVENTIONS: Five 3-s forced expiratory maneuvers were used for each of 3 sequential portions of the study: baseline, after nebulized saline solution, and after nebulized albuterol. SETTING: Clinical pulmonary function laboratory in a county/university teaching hospital. PATIENTS: Fifty consecutive adult patients with obstruction referred for routine testing and thought to be able to complete the study. (The primary diagnoses were found to be equally divided between asthma, bronchitis, and emphysema; equal numbers had very severe, severe, moderate, mild, or minimal obstruction.) MEASUREMENTS AND RESULTS: The primary finding was that 36 patients were found to be responders (consistent and statistically significant FEV1 and FEV3 improvement after albuterol). The 14 identified as nonresponders would have been so categorized by all other published criteria. For assessing responsiveness, we found FEV3 measures preferable to vital capacity measures, because the latter depends on the duration of the maneuver. CONCLUSIONS: The percentage of responders identified is higher than recognized by any other published criteria. Most criteria would not have identified the responders with very severe or minimal airways obstruction.

Aerosols↗
PubMed1993

Evaluation of the combination effect of different antiviral compounds against HIV in vitro.

3'-azido-3'deoxythymidine (AZT), a clinically used anti-HIV compound, was evaluated for antiviral effect on HIV infection in combination with other antiviral compounds in vitro. Interactions were evaluated by the median-effect principle and the isobologram technique. Synergistic effect was obtained by combining many evaluated antiviral agents with AZT. We observed a difference in the degree of synergism depending on the evaluated compound; the results indicate that compounds with the same target in the viral replicative cycle (ddI: 2',3'-dideoxyinosine, didanosine; d4T: 2',3'-dideoxy-2',3'-didehydrothymidine stavodine; TIBO: tetrahydro-imidazole-benzodiazepin) had a synergistic effect at all concentrations, agents that disturb the infectivity of virus (CAS: Castanospermine; AME: Amphotericin B Methyl Ester) exerted a strong synergistic effect at low concentrations, and finally compounds interfering with the adhesion/penetration process of virus (ConA: Concanavalin A; DS: dextran sulfate) were most potent with AZT when used in rather high concentrations. At this moment in the HIV epidemic, these observations suggest that combinations of antiviral compounds should be evaluated in clinical trials, with the major emphasis on nucleoside analogues and compounds influencing the infectivity of the virus.

Antiviral Agents↗
PubMed1993

Enhancement of retroviral infection in vitro by anti-Le(y) IgG: reversal by humanization of monoclonal mouse antibody.

Monoclonal mouse IgG3 antibody (ABL 364) against the carbohydrate Le(y) antigen enhanced infection in vitro with HTLV-1 and with HIV-1 when propagated in both transformed and normal lymphocytes. Enhancement was independent of complement, occurred with both lymphocytes and monocytes as target cells, and did not use either L(ey) epitopes on target cells for cross-linkage of virus to the cell or the Fc part of the antibody as a ligand for any cellular receptor. For enhancement to occur, binding of anti-Le(y) antibody to virus was required to take place before virus binding to its specific receptor with no indication of any alternative pathway of infection, as evidenced by abrogation of enhancement by anti-CD4 MAb or soluble recombinant CD4, and also the inability of anti-Le(y) MAb to mediate HIV infection of HSB-2 cells in which HTLV-1/HIV pseudovirus infection was enhanced. While F(ab)2 fragments of ABL 364 also enhanced infection, a human/mouse chimeric antibody and a fully humanized antibody had no enhancing effect on free virus infection. We suggest that binding of anti-Le(y) ABL 364 or its F(ab)2 fragment induced a conformational change in the gp120 oligomers facilitating the process of infection, and that this function was abrogated by the IgG1 Fc of the chimeric and the humanized antibodies. The observations indicate that the non-paratope domains of antiviral antibodies can influence their function as neutralizing or enhancing for infection.

Animals↗
PubMed1993

Glycosylation of the major human Pneumocystis carinii surface antigen.

It has recently been shown that the major rat P. carinii surface antigen is important for initial host-organism attachment, possibly through binding to fibronectin, mannose-binding protein, or surfactant protein A. Since a carbohydrate/lectin interaction may be involved in adhesion, we undertook this study to characterize the glycosylation of the major human P. carinii surface glycoprotein (gp95). We have used purified gp95 as a source of antigen, and in lectin binding and deglycosylation studies it was found that approximately 9% of gp95 consists of N-linked carbohydrates of mainly high-mannose and bisected complex-type glycans. Using a polyclonal antibody raised against purified gp95 and crossed affinoimmunoelectrophoresis and the lectins Con A and WGA, gp95 exhibited carbohydrate-dependent microheterogeneity. We therefore suggest that gp95 is composed of subtypes which differ in N-linked glycosylation.

Antigens, Fungal↗