Biomedical subjects
Publications and source records attributed to R Pauwels.
26 months after the onset of alcohol-induced pain, a diagnosis of primary pulmonary Hodgkin's (PPHD) disease could be made in a 34-year-old woman. Standard radiology of the thorax remains normal up to 18 months after the onset of symptoms. A short review of the literature concerning PPHD is given.
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Various polyoxometalates proved inhibitory to the replication of a number of enveloped DNA and RNA viruses, i.e., herpesviruses (herpes simplex and cytomegalo), togaviruses (Sindbis), paramyxoviruses (respiratory syncytial), rhabdoviruses (vesicular stomatitis), arenaviruses (Junin and Tacaribe), and retroviruses [human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2), simian immunodeficiency virus, and murine sarcoma virus]. The most potent compounds, i.e., JM1590 [K13[Ce(SiW11O39)2]. 26H2O] and JM2766 [K6[BGa(H2O)W11O39]. 15H2O], inhibited HIV-1 and simian immunodeficiency virus at concentrations as low as 0.008-0.8 microM. The polyoxometalates also inhibited giant cell formation in co-cultures of HIV-infected HUT-78 cells and uninfected MOLT-4 cells. Studies designed to unravel the mechanism of action of these compounds revealed that they inhibit the reverse transcriptase activity associated with HIV. The polyoxometalates also proved inhibitory to the binding of HIV-1 virions to the cells. From "time of addition" experiments, whereby the polyoxometalates were added at different times after virus infection, their mechanism of anti-HIV action could be attributed to inhibition of virus-cell binding. There was a good correlation (r = 0.84) between the inhibitory effects of the compounds on HIV-1-induced cytopathicity and their inhibitory effects on syncytium formation and a close correlation (r = 0.902) between their inhibitory effects on syncytium formation and their interaction with gp120, whereas there was no correlation between their anti-HIV-1 activity and their inhibitory effects on HIV-1 reverse transcriptase. In flow cytometric studies, the compounds did not interfere with the binding of OKT4A/Leu-3a monoclonal antibody to the CD4 receptor of uninfected cells, but they inhibited binding of anti-gp120 monoclonal antibody to HIV-1-infected cells. Thus, the binding of the polyoxometalates to the viral envelope glycoprotein gp120 is responsible for their anti-HIV activity.
The reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is present in virions and infected cells as an heterodimer (p66/p51). A new class of potent and selective HIV-1 inhibitors, the tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione (TIBO) derivatives, were found to exert their antiviral activity by interacting with monomeric HIV-1 RT (p66) in a way different from that of previously studied RT inhibitors such as azidothymidine 5'-triphosphate. Upon examination of the kinetic properties of the heterodimeric HIV-1 RT and its inhibition by TIBO compounds, a positive cooperativity between the subunits of the enzyme with regard to the 2'-deoxynucleoside 5'-triphosphates and the template/primer was observed. The cooperativity with respect to the template/primer may result from a progressive dimerization in the presence of increasing concentrations of the template/primer, a process referred to as polysteric linkage. Because the cooperativity of p66/p51 was abolished in the presence of TIBO, these compounds behave as allosteric inhibitors.
Recently, several classes of compounds have been shown to be potent, selective, and specific inhibitors of human immunodeficiency virus type 1 replication in vitro. These include the tetrahydroimidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-one and -thione (TIBO) and the 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) derivatives. Both the TIBO and HEPT derivatives specifically inhibit human immunodeficiency virus type 1 reverse transcriptase (RT). From a comparative study of the characteristics of RT inhibition by TIBO and HEPT, and from the competition between TIBO and HEPT for RT inhibition, we infer that both classes of compounds, although structurally unrelated, are targeted at the same site of the enzyme. Detailed functional and kinetic analyses indicate that this target site is functionally and possibly also spatially related to the substrate binding site.
A term female firstborn infant had unexplained nonimmune fetal hydrops and recurrent left chylothorax at 4 weeks of age. A few months before conception, her mother had had acute dystrophic nail changes and is being treated for recurrent sinusitis, bronchiectasis, and a deficiency of serum IgG2. We suggest that they both suffer from a dominantly inherited congenital lymphedema syndrome known as 'yellow nail dystrophy.' Prenatal manifestation of this disorder has not been reported previously. The child's anthropometric and neurological development was normal at 1 year of age, whereas mild ankle edema and marbling of the skin of the limbs were salient clinical findings. Inherited lymphedema leading to nonimmune fetal hydrops also has been recognized in chromosomal disorders, Noonan's syndrome, multiple pterygium syndrome, pulmonary lymphangiectasis, and mixed-vessel lymphatic dysfunction. Indicators of parental lymphedema are not on record in those instances.
Screening of pharmacologically acceptable prototype compounds has recently led to the discovery of a series of ultraselective inhibitors of human immunodeficiency virus (HIV)-1 replication, the tetrahydroimidazo[4,5,1-jk] [1,4]-benzodiazepin-2(1H)-one and -thione (TIBO) derivatives. The TIBO compounds completely suppress the formation of proviral DNA in acutely infected cells, as revealed by polymerase chain reaction (PCR) analysis. TIBO derivatives are inhibitory to the reverse transcriptase (RT) of HIV-1 but not that of HIV-2 or other retroviruses. The inhibition is most effective with poly(C)-oligo(dG) as the template/primer, and it is selectively directed against the RNA-dependent DNA polymerase activity and not the accompanying DNA-dependent DNA polymerase and ribonuclease H activity of HIV-1 RT. Kinetic studies point to an uncompetitive inhibition with regard to the template/primer. TIBO compounds are active against HIV-1 replication through a unique interaction with HIV-1 RT. The experimental data indicate the existence of a target on HIV-1 RT that is responsible for the inhibition of replication and a mode of action unrelated to that of previously studied RT inhibitors.
R82913, (+)-S-4,5,6,7-tetrahydro-9-chloro-5-methyl-6-(3-methyl-2-butenyl)- imidazo[4,5,1-jk][1,4]-benzodiazepin-2(1H)-thione (a TIBO derivative), inhibited the replication of thirteen different strains of HIV-1 in CEM cells with a median IC50 of 0.15 microM. The concentration of compound that killed 50% of the cells was much higher (46 microM), indicating that R82913 has a high selectivity index. R82913 was 20-fold more potent than AZT-TP in the inhibition of HIV-1 reverse transcriptase in an assay using a naturally occurring template (ribosomal RNA) that more accurately resembles native viral RNA than a synthetic homopolymer. With this template, R82913 inhibited HIV-1 reverse transcriptase with an ID50 (0.01 microM) that is equal to, or lower than, the IC50 for this compound in all of our cell culture assays (0.01-0.65 microM). R82913 has no effect on the replication of HIV-2 in CEM cells and does not inhibit the reverse transcriptase from this virus.
A series of 6-substituted 4,5,6,7-tetrahydro-5-methylimidazo[4,5,1-jk][1,4]benzodiazepin- 2(1H)-ones (9) have been synthesized and tested for their ability to inhibit the replication of the HIV-1 virus in MT-4 cells. Two synthetic methods are described, one of which allows the synthesis of single enantiomers of the final products. A structure-activity study was done within the series of compounds to determine the optimum group for the 6-position substitution and to determine whether the activity was enantiospecific at the 5-position, which was substituted with a methyl group. The best analogue, 9jj, inhibited HIV-1 with an IC50 of 4 microM, which is comparable to the activity level of DDI, a 2',3'-dideoxynucleoside-type structure undergoing clinical trials as an anti-AIDS therapy.
In the first paper of this series a new structure with anti-HIV-1 activity was disclosed and analogues were synthesized to explore the structure-activity relationship of changes in the substituent (R) attached at the N-6 position of 9. This study describes the syntheses and anti-HIV-1 testing of analogues with variations of the five-membered urea ring of the 4,5,6,7-tetrahydro-5-methylimidazo[4,5,1-jk] [1,4]benzodiazepin-2(1H)-one (TIBO) structures. Although many different rings were synthesized to replace the cyclic urea of TIBO, most were found to be inactive in inhibiting the replication of the HIV-1 virus in MT-4 cells. The exceptions were replacement of the urea oxygen with sulfur or selenium to give the corresponding thio- or selenoureas. These were found to be more active than the oxygen counterparts. A small series of analogues was synthesized and tested which allowed direct comparison of urea and thiourea derivatives. Without exception, the latter were always more active than the former. The most active compound of this series (8d) was found to inhibit the HIV-1 virus with an IC50 of 0.012 microM which is comparable to that of AZT.
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The IgG subclass specific immune response against pneumococcal type 3 polysaccharide antigen before and after immunisation in healthy children and children with recurrent bronchitis was studied. Recurrent bronchitis was defined as three or more episodes a year, during at least two consecutive years, of bronchopulmonary infection, productive cough with or without fever, and/or diffuse rales by physical examination. Twenty five patients and 15 healthy children were selected. The patient group had lower concentrations of IgG1 and IgG2 specific pneumococcal antibodies compared with healthy children, regardless of whether or not the total IgG2 concentration was low. The children with recurrent bronchitis showed a greater increase in IgG1 and IgG2 antibodies after immunisation than the controls. It is concluded that children with recurrent bronchitis show a decreased humoral immune response to pneumococcal type 3 polysaccharide antigen. This finding suggests that a defect in the humoral immune response against polysaccharide antigens is an important cause of recurrent bronchitis in childhood.
Tracheobronchomegaly (TBM) is a rare disorder of uncertain aetiology, characterized by marked dilatation of the trachea and main bronchi, bronchiectasis and recurrent lower respiratory tract infections. Two patients with TBM are presented. In one case, a marked decrease of elastic and smooth muscle tissue was present in the bronchial biopsy specimens, obtained by rigid bronchoscopy. The airways of the second patient were visualized using computed tomography. The dimensions of the airways of our patients are compared with the normal values supplied in the literature.
The human immunodeficiency virus (HIV) is a lentivirus which replicates within critical cells of the immune system, particularly CD4+ T-cells and monocyte/macrophages, leading to a progressive loss of helper T-cells and profound immunosuppression. This condition is known as the acquired immunodeficiency syndrome (AIDS). A rational screening strategy was adopted to evaluate new anti-HIV agents. Primary in vitro evaluation of antiviral compounds and studies of the relationship between structure and antiviral activity were carried out in a CD4+ T-cell line (MT-4). These cells develop a cytopathic effect (CPE) within a few days after infection. Initially, protection against the HIV-induced cytopathic effect as well as the MT-4 host cell cytotoxicity was determined by a highly automated evaluation system. Promising lead compounds emerging from these studies were then further investigated for their anti-HIV properties in other target cells and against different HIV-1 and HIV-2 strains. This strategy allowed the identification of several potent and selective inhibitors of HIV replication in vitro. Following the 3'-azidothymidine (AZT) lead, we synthesized and evaluated other 2',3'-dideoxynucleoside analogues with modifications in the base and/or sugar moiety. Based on their selectivity indexes in vitro, several congeners of this group, including 2',3'-thymidine (ddeThd, D4T) and 5-chloro-3'-fluoro-2',3'-dideoxyuridine (FddClUrd), seem at least as promising as AZT. From a series of phosphonylmethoxyalkylpurines and -pyrimidines, 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and 9-(2-phosphonylmethoxyethyl)-2,6-diaminopurine (PMEDAP) emerged as a new class of broad-spectrum anti-retrovirus agents. Sulfated polysaccharides and sulfated polymers represent another class of compounds achieving high therapeutic indexes in vitro. Comparative studies allowed to define the structural requirements for anti-HIV activity. Finally, a rational screening strategy allowed the identification of tetrahydro-imidazo[4,5,1-jk][1,4]-benzodiazepine-2(1H)-one and -thione (TIBO) derivatives which represent a complete new class of anti-HIV-1 agents.(ABSTRACT TRUNCATED AT 400 WORDS)
A series of neoglycoproteins was synthesized by coupling of thiophosgene-activated p-aminophenyl derivatives [Biol. Cell. 47:95-110 (1983); J. Histochem. Cytochem. 32:1091-1094 (1984)] of various sugars to human serum albumin. The compounds were evaluated for their in vitro activity against human immunodeficiency virus (HIV). Neoglycoproteins with the highest sugar content were found to be the most potent inhibitors of HIV-1-induced cytopathogenicity. However, this was not due to the nature of the sugar used but, rather, was related to the extra negative charge of the neoglycoproteins. To investigate whether the antiviral activity of the neoglycoproteins exhibited sugar specificity, increased with increasing negative charge, or depended on both sugar specificity and negative charge, we synthesized albumins and neoglycoproteins with an enhanced negative charge, by treatment with formaldehyde or succinic anhydride. Succinylated human serum albumin had the most pronounced net negative charge and had an IC50 of about 1 microgram/ml. No cytotoxicity was observed at concentrations up to 1 mg/ml, implicating a selectivity index (CC50/IC50) of at least 10(3). To elucidate the mechanism of action of these anionic albumins, we investigated whether they interfered with HIV-1 adsorption to the cells, binding of anti-OKT4A monoclonal antibody (mAb) to the CD4 receptor, binding of anti-gp120 mAb to gp120, or inhibition of syncytium formation in co-cultures of HIV-1-infected HUT-78 cells with MOLT-4 cells. From these experiments, we conclude that albumins with an increased negative charge (a) are potent and nontoxic anti-HIV-1 agents, (b) cause a 50% reduction of syncytium formation in the same concentration range as their IC50 in the antiviral assay, and (c) do not bind to the OKT4A epitope of the CD4 receptor and only partly inhibit anti-gp120 mAb-gp120 interaction and virus-cell binding at concentrations that are 100 times higher than their IC50 in the antiviral assay. Therefore, we conclude that the modified albumins interfere with a post-binding event, of which one of the potential mechanisms is an interaction with the gp41 fusion protein, which is necessary for syncytium formation but is not involved in initial virus binding.
The delivery of the anti-HIV agent 3'-azido-3'-deoxythymidine (AZT), in its 5'-monophosphate form, (in) to human T-lymphocyte MT-4 cells in vitro through covalent coupling to neoglycoproteins was investigated. In vivo application of this drug targeting concept may lead to increased efficacy and/or diminished side effects caused by AZT during the treatment of AIDS and ARC patients. The rationale for the design of the neoglycoprotein carriers is based on the existence of sugar recognizing lectins on T-lymphocytes. Using a phenyl-linkage between sugar and Human Serum Albumin (HSA), various mannose-, fucose-, galactose-and glucose-containing neoglycoproteins were synthesized. The intrinsic anti-HIV activity of these neoglycoproteins was tested in vitro in HIV-1 infected MT-4 cells. Only the derivative having 40 moles mannose per mole protein (Man40HSA) shows pronounced anti-HIV-1 activity itself. This effect may be caused by interference of the Man40HSA with the gp120-CD4 mediated virus/MT-4 cell interaction. After conjugation with AZTMP, the mannose- as well as the fucose- and galactose-containing conjugates exhibited a pronounced activity. Conjugates of glucose-HSA and HSA displayed much less activity in spite of the fact that drug loading was considerably higher, compared with the galactose, mannose and fucose derivatives. In the series of mannose-neoglycoproteins, the Man22HSA-AZTMP conjugate was shown to be more than 30 times as active against HIV-1 compared to HSA-AZTMP. Selectivity indices of Man7 and Man22HSA-AZTMP were exceeding the AZT and AZTMP indices, indicating that these conjugates possess a more selective action. Stability experiments indicate that the potent action of the galactose-, mannose- and fucose-HSA-AZTMP conjugates is not due to a complete extracellular hydrolysis of the covalent drug-protein bond. Since Man22HSA has no intrinsic activity in the concentration range used, the antiviral effect is unlikely to be explained by synergism of the neoglycoprotein by a component of the cell membrane and subsequent internalization and release of the drug from the conjugate may play a role.
In the search for compounds active against human immunodeficiency virus (HIV), we have found that members of a novel series of tetrahydro-imidazo[4,5,1-jk][1,4]-benzodiazepine-2(1H)-one and -thione (TIBO) derivatives inhibit the replication of HIV-1, the main aetiological agent of AIDS, but not of HIV-2, or of any other DNA or RNA viruses. In five cell systems, HIV-1 is inhibited by TIBO derivatives in nanomolar amounts, which are 10(4)-10(5) times lower than the cytotoxic concentration. The unprecedented specificity of these compounds may be due to an interaction with a reverse transcriptase-associated process. By contrast, AZT (3'-azido-2',3'-dideoxythymidine), which is used for the treatment of AIDS, and DDC (2',3'-dideoxycytidine) and DDI (2',3'-dideoxyinosine), whose clinical application is being assessed, inhibit both HIV-1 and HIV-2 at concentrations that, depending on the cell systems, are 2 to 4 orders of magnitude below their cytotoxic concentration. TIBO-derivatives are new chemicals unrelated to any other antiviral agents. We believe that they are the most specific and potent inhibitors of HIV-1 replication studied so far.
Syncytium formation between HUT-78 cells persistently infected with human immunodeficiency virus type 1 (HIV-1) and uninfected CD4-bearing MOLT-4 or CEM cells results in a rapid destruction of the MOLT-4 or CEM cells. This syncytium formation is due to the interaction between the gp120 glycoprotein expressed by the persistently HIV-1-infected HUT-78 cells and the CD4 receptor present on MOLT-4 or CEM cells. A flow cytometric method has been applied to separate the infected (HUT-78) from the uninfected (MOLT-4, CEM) cell populations. This method is based on a modified DNA staining protocol which clearly shows the differences in DNA content between HUT-78 cells, on the one hand, and MOLT-4 or CEM cells, on the other hand. Using this flow cytometric method we have demonstrated that those compounds (i.e., sulfated polysaccharides, aurintricarboxylic acid) that interact with gp120 (of the HIV-infected cells) or CD4 (of the uninfected cells) suppress syncytium formation and concomitant destruction of the CD4+ cells.