Biomedical subjects

W W Hall

Publications and source records attributed to W W Hall.

At least 19 recordsLinked to original sources

PubMed1992

In vivo cellular tropism of human T cell leukemia virus type II (HTLV-II).

To investigate the in vivo cellular tropism of human T cell leukemia virus type II (HTLV-II), subpopulations of fresh peripheral blood mononuclear cells from infected individuals were isolated and analyzed by polymerase chain reaction for the presence of provirus. In eight of nine patients, HTLV-II was detected exclusively in the CD8+ T lymphocyte population. In the remaining patient, provirus was also detected in CD4+ T lymphocytes. Provirus was not detected in B lymphocytes or monocytes of any patient. These results suggest that in vivo HTLV-II has a preferential, and perhaps in some cases, an exclusive tropism for CD8+ T lymphocytes. The findings contrast sharply with those on HTLV-I where there is a preferential tropism for CD4+ T lymphocytes. Although HTLV-II infection has not been consistently associated with any lymphoproliferative disorders, the results suggest that if these occur, they may be different from those known to be associated with HTLV-I.

Adult↗

PubMed1992

Multiple isolates and characteristics of human T-cell leukemia virus type II.

Human T-cell leukemia (or lymphotropic) virus type II (HTLV-II) was isolated from eight HTLV-seropositive patients, six of whom were also infected with human immunodeficiency virus, by cocultivation of peripheral blood mononuclear cells (PBMCs) with BJAB, a continuous B-cell line. Restriction endonuclease mapping of the proviruses demonstrated consistent differences among isolates, and two distinct physical map patterns were observed. The results suggest the existence of two closely related molecular subtypes of HTLV-II, which are tentatively designated HTLV-IIa and HTLV-IIb. This finding was supported by preliminary nucleotide sequence analysis of the env gene region encoding the transmembrane glycoprotein gp21, which showed consistent differences between the two proposed virus subtypes. Exploitation of differences in restriction endonuclease sites allowed polymerase chain reaction amplification to detect and differentiate the two subtypes in fresh PBMCs of HTLV-seropositive intravenous drug abusers (IVDAs). The results of these studies confirm that HTLV-II infection is the prominent HTLV infection in seropositive IVDAs and also show that infection with both subtypes occurs. The finding of genetic heterogeneity in the HTLV-II group of viruses may have important implications for studies on its role in human disease and will be useful in characterizing the viruses present in newly discovered endemic foci in New World indigenous populations.

Adult↗

PubMed1991

Deleted HTLV-I provirus in blood and cutaneous lesions of patients with mycosis fungoides.

Mycosis fungoides, a rare form of cutaneous T cell leukemia/lymphoma, is suspected of having a viral etiology on the basis of certain similarities to adult T cell leukemia, which is associated with human T cell leukemia/lymphoma virus type I (HTLV-I) infection. Cell lines were established from peripheral blood mononuclear cells (PBMC) of an HTLV-I-seronegative patient with mycosis fungoides. DNA hybridization analysis revealed the presence of HTLV-I-related sequences with unusual restriction endonuclease sites. Sequence analysis of subcloned fragments demonstrated the presence of a monoclonally integrated provirus with a 5.5-kilobase deletion involving large regions of gag and env and all of pol. Additional evidence for the presence of deleted proviruses was found by polymerase chain reaction (PCR) amplification of DNA from cutaneous lesions of five other HTLV-I-seronegative patients. The findings suggest that HTLV-I infection may be involved in the etiology of at least certain cases of mycosis fungoides.

Base Sequence↗

PubMed1991

Identification of type-specific linear epitopes in the glycoproteins gp46 and gp21 of human T-cell leukemia viruses type I and type II using synthetic peptides.

Synthetic peptides of 20-25 amino acids were employed in enzyme-linked immunosorbent assays to identify linear epitopes in the external glycoprotein gp46 and the transmembrane glycoprotein gp21 of human T-cell leukemia/lymphotropic viruses type I (HTLV-I) and II (HTLV-II). Ten linear epitopes were identified in the HTLV-I glycoproteins, seven in gp46 and three in gp21. Three major linear epitopes were identified in the gp46 of HTLV-II. Peptides representing linear epitopes of gp46 were found to be sensitive and specific for the detection of antibody and permit serological identification and differentiation of HTLV-I and HTLV-II infections.

Amino Acid Sequence↗

PubMed1991

Distribution of atrial natriuretic peptide in the conduction system and ventricular muscles of the human heart.

Atrial natriuretic peptide (ANP), a cardiac hormone, is known to be located in the atrial specific granules, but its presence and localization in the ventricular muscle of the human heart has not been examined fully. Using a specific antibody to human ANP, we studied the conduction system and ventricular muscle with immunohistochemical and ultrastructural methods in 30 hearts obtained at autopsy. These included 12 normal and 18 diseased hearts. In the normal hearts, ANP-positive granules, which were regularly observed in the atrial myocytes, were found in small quantities in the cells of the penetrating and branching bundles in 4 of 12, and in the cells of the ventricular free walls in 2 of the 12 hearts. In the diseased hearts, the positivity increased significantly (P less than 0.05), being found in 13 of 18 (72.2%) conduction systems and 10 of 18 (55.6%) ventricular muscles. The granules were confirmed to be immunoreactive with ANP by ultrastructural examination. Furthermore, the presence of ANP mRNA in the conduction system as well as in the ventricular myocytes was demonstrated by Northern blot hybridization for which we used the complementary DNA of human ANP. Thus, a small quantity of ANP appears to be synthesized and stored in the conduction system and ventricles of some normal hearts. However, ANP was shown to be present in a larger percentage of the diseased hearts.

Aged↗

PubMed1991

Syndrome of severe skin disease, eosinophilia, and dermatopathic lymphadenopathy in patients with HTLV-II complicating human immunodeficiency virus infection.

Two intravenous drug users dually infected with human immunodeficiency virus type 1 (HIV-1) and human T-cell leukemia virus type II (HTLV-II) developed an unusual severe dermatitis characterized by progressive brawny induration, fissuring, and ulceration of the skin, with an associated CD8 cell infiltration in one patient. Both patients had persistent eosinophilia. Lymph node biopsy revealed dermatopathic lymphadenopathy, an unusual pathologic finding in HIV-1 infection but one seen in association with mycosis fungoides and other skin disorders. Two new isolates of HTLV-II virus were established from these patients and were identified as HTLV-II by Southern blotting. This type of skin disease and lymph node pathology has not been found in other intravenous drug users who have been infected with HIV-1 alone or in patients in other risk groups for HIV-1 infection. HTLV-II may play a role in this unique new disease pattern in patients infected with HIV-1.

Adult↗

PubMed1991

Pathological features of virus infections of the central nervous system (CNS) in the acquired immunodeficiency syndrome (AIDS).

Neurological disorders are a common cause of morbidity and mortality in the acquired immunodeficiency syndrome (AIDS). In this report we describe the neuropathological changes associated with both human immunodeficiency virus (HIV) infection and with the major opportunistic virus infections, cytomegalovirus (CMV), JC papovavirus (JCV) and herpes simplex virus (HSV) seen in AIDS. In addition "in situ" hybridization studies have been employed for the detection of virus genomic material in each case and the usefulness of this method in supporting the pathological diagnosis is demonstrated. Mechanisms whereby HIV infection results in leukoencephalopathy and the possible contributing roles of the three opportunistic virus infections are discussed.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Japanese encephalitis virus neurotropism is dependent on the degree of neuronal maturity.

In a study on Fischer rats, all animals infected with Japanese encephalitis virus (JEV) before the age of 13 days died, but animals infected after the age of 14 days did not die, confirming the age-dependent resistance to JEV infection in the rat brain. A study of the kinetics of JEV infection in the developing rat brain disclosed that JEV antigen disappeared in a particular pattern, i.e., from the deeper layers to the upper layers of the motor cortex, which paralleled neuronal maturation in the cortex. Fifteen-day-old rats, which were resistant to JEV infection, received intracerebral transplants of neurons taken from 19-day embryos. When these animals were infected with JEV after transplantation, viral antigen was detected only in the embryonal neurons soon after transplantation. Thus, it can be concluded that the susceptibility to JEV infection in the rat brain is closely associated with neuronal immaturity.

Aging↗

PubMed1991

Continuous epitopes of the human immunodeficiency virus type 1 (HIV-1) transmembrane glycoprotein and reactivity of human sera to synthetic peptides representing various HIV-1 isolates.

Immunoreactive regions of human immunodeficiency virus type 1 (HIV-1) gp41 were mapped by reacting HIV-1 antibody-positive human sera with overlapping synthetic peptides which covered the transmembrane protein. Three immunoreactive domains were identified, and five different and partially overlapping epitopes recognized by HIV-1-positive human sera were found within one immunodominant region. The effect on antibody recognition after single amino acid substitutions within one defined epitope was also studied. The reactivity of various HIV-1-positive sera to synthetic peptides with amino acid substitutions representing known isolates suggests an important substitution in the major epitope of African HIV-1 strains.

Amino Acid Sequence↗

PubMed1990

Human immunodeficiency virus type 1 envelope glycoprotein gp120 produces immune defects in CD4+ T lymphocytes by inhibiting interleukin 2 mRNA.

Envelope glycoprotein gp120 of human immunodeficiency virus type 1 (HIV-1) is known to inhibit T-cell function, but little is known about the mechanisms of this immunosuppression. Pretreatment of a CD4+ tetanus toxoid-specific T-cell clone with soluble gp120 was found to exert a dose-dependent inhibition of soluble antigen-driven or anti-CD3 monoclonal antibody-driven proliferative response, interleukin 2 (IL-2) production, and surface IL-2 receptor (IL-2R) alpha-chain expression, all of which were reversed by the addition of exogenous IL-2. mRNA for the gene encoding IL-2 was suppressed by treatment with gp120, but IL-2R gene transcription was not inhibited. Bypass activation of the T-cell clone with phorbol 12-myristate 13-acetate plus ionomycin was unaffected by gp120 pretreatment. Thus, gp120-CD4 interaction interferes with an essential role of the CD4 molecule in signal transduction through the CD3-antigen receptor (Ti) complex. Such a mechanism of gp120-induced immunosuppression, if operative in vivo, could contribute to the depressed specific immune responses associated with HIV infection.

Antigens, CD↗

PubMed1990

Purine nucleoside phosphorylase: purification using an ether-linked formycin B/sepharose 6B resin with unusual properties.

Formycin B [9-deazainosine] was reacted with epoxy-activated Sepharose 6B to form an affinity resin for purine nucleoside phosphorylase (PNPase). This resin had a large capacity (7,600 units/ml) for the enzyme from Escherichia coli. Enzyme retention was dependent on high ionic strength. Although this property is reminiscent of hydrophobic interaction chromatography, analogous resins prepared with pseudouridine or monoethanolamine instead of with formycin B, did not retain the enzyme even at high ionic strength. Furthermore, hypoxanthine facilitatted elution of the enzyme from the resin. It appeared, therefore, that the enzyme was not bound simply by hydrophobic interactions. A simple two-step purification procedure for PNPase from Escherichia coli was devised using this resin. Overall recovery was 50%, and purity of the final preparation was greater than 95%. This resin was also useful in the purification of PNPase from human erythrocytes. The ether linkage between formycin B and Sepharose 6B, together with the carbon-to-carbon linkage between the pentose and heterocyclic moieties of formycin B, provided stability to both chemical and enzymatic degradation. After 5 years of use and exposure to a variety of biological preparations, the resin showed no detectable decrease in its ability to bind PNPase.

Electrophoresis, Polyacrylamide Gel↗

PubMed1989

Inhibition of xanthine oxidase by 4-hydroxy-6-mercaptopyrazolo[3,4-d]pyrimidine.

Compound B103U, 4-hydroxy-6-mercaptopyrazolo[3,4-d]pyrimidine, was investigated as an inhibitor of human xanthine oxidase. Studies in vitro demonstrated that it was significantly more potent than oxypurinol, 4,6-dihydroxypyrazolo[3,4-d]pyrimidine. It formed an initial complex with electron-rich (reduced) human xanthine oxidase that was tighter than the corresponding complex formed by oxypurinol. The initial complexes with each inhibitor and reduced enzyme were internally rearranged into more stable complexes with first-order rate constants of 2.5 to 3 per min. However, the half-life of the isomerized (stable) complex with B103U was three to four times longer than the half-life of the analogous complex with oxypurinol. This stability was previously noted by Massey et al. (J. Biol Chem 254: 2837-2844, 1970) with B103U and bovine xanthine oxidase. The overall Ki values accounting for the initial and isomerized complexes were 5 nM for B103U and 100 nM for oxypurinol. B103U was also more potent as an inhibitor of bovine xanthine oxidase-catalyzed generation of superoxide radicals. Studies in mice revealed that the relative in vitro potency of B103U was not sustained in vivo. Compared to the inhibition of xanthine oxidase by oxypurinol, inhibition by B103U was neither more potent nor longer lasting. This shortcoming was not caused by weaker inhibition of mouse xanthine oxidase. Instead, it was the result of poor bioavailability. Plasma levels of available B103U rapidly decreased from samples of mouse and human blood because of reversible binding to serum proteins. B103U was also susceptible to oxidation. Two equivalents of H2O2 stoichiometrically oxidized the 6-thiol substituent to a sulfinic acid. This oxidized product was three orders of magnitude weaker as an inhibitor of xanthine oxidase than was B103U.

Animals↗

PubMed1989

Nucleosides of azathioprine and thiamiprine as antiarthritics.

Azathioprine [Imuran; 6-[(1-methyl-4-nitro-1H-imidazol-5-yl)thio]-1H-purine] is a widely used immunosuppressive and antiarthritic drug. For the sake of comparison, the riboside, the 2'-deoxyriboside, and the arabinoside of azathioprine and its 2-amino congener, thiamiprine, were prepared by an enzymatic method. In vitro, the cytotoxicities of these aglycons and their nucleosides were similar (ED50 = 0.8-2 microM), except for the arabinosides, which were nontoxic (ED50 greater than 100 microM). In vivo, their activities were compared in the rat adjuvant arthritis model. The ribosides and 2'-deoxyribosides were less potent than their corresponding aglycons. The safety indexes of these nucleosides were comparable to those of the corresponding aglycons except for the 2'-deoxyriboside of azathioprine, which had an appreciably lower safety index than did azathioprine. Both arabinosides were inactive and nontoxic. All of the aglycons tested (6-mercaptopurine, azathioprine, 6-thioguanine, and thiamiprine) were of similar potency. However, azathioprine had a more favorable therapeutic index than did 6-mercaptopurine. Similarly, thiamiprine was safer than was 6-thioguanine. In this model, the S-(1-methyl-4-nitro-1H-imidazol-5-yl) moiety imparted greater safety to these thiopurines by decreasing toxicity but not affecting potency.

Animals↗

PubMed1988

Purification and properties of inosine-guanosine phosphorylase from Escherichia coli K-12.

A xanthosine-inducible enzyme, inosine-guanosine phosphorylase, has been partially purified from a strain of Escherichia coli K-12 lacking the deo-encoded purine nucleoside phosphorylase. Inosine-guanosine phosphorylase had a particle weight of 180 kilodaltons and was rapidly inactivated by p-chloromercuriphenylsulfonic acid (p-CMB). The enzyme was not protected from inactivation by inosine (Ino), 2'-deoxyinosine (dIno), hypoxanthine (Hyp), Pi, or alpha-D-ribose-1-phosphate (Rib-1-P). Incubating the inactive enzyme with dithiothreitol restored the catalytic activity. Reaction with p-CMB did not affect the particle weight. Inosine-guanosine phosphorylase was more sensitive to thermal inactivation than purine nucleoside phosphorylase. The half-life determined at 45 degrees C between pH 5 and 8 was 5 to 9 min. Phosphate (20 mM) stabilized the enzyme to thermal inactivation, while Ino (1 mM), dIno (1 mM), xanthosine (Xao) (1 mM), Rib-1-P (2 mM), or Hyp (0.05 mM) had no effect. However, Hyp at 1 mM did stabilize the enzyme. In addition, the combination of Pi (20 mM) and Hyp (0.05 mM) stabilized this enzyme to a greater extent than did Pi alone. Apparent activation energies of 11.5 kcal/mol and 7.9 kcal/mol were determined in the phosphorolytic and synthetic direction, respectively. The pH dependence of Ino cleavage or synthesis did not vary between 6 and 8. The substrate specificity, listed in decreasing order of efficiency (V/Km), was: 2'-deoxyguanosine, dIno, guanosine, Xao, Ino, 5'-dIno, and 2',3'-dideoxyinosine. Inosine-guanosine phosphorylase differed from the deo operon-encoded purine nucleoside phosphorylase in that neither adenosine, 2'-deoxyadenosine, nor hypoxanthine arabinoside were substrates or potent inhibitors. Moreover, the E. coli inosine-guanosine phosphorylase was antigenically distinct from the purine nucleoside phosphorylase since it did not react with any of 14 monoclonal antisera or a polyvalent antiserum raised against deo-encoded purine nucleoside phosphorylase.

Escherichia coli↗

PubMed1987

Crystallization and preliminary x-ray investigation of thymidine phosphorylase from Escherichia coli.

Crystals of thymidine phosphorylase from Escherichia coli have been grown from solutions of ammonium sulfate. The crystals are tetragonal, space group P4(1)2(1)2 or P4(3)2(1)2; the axes are a = 132.0 (1) and c = 67.2 (1) A. The crystals are quite stable to x-rays and diffract beyond 2.6-A resolution. The molecule is a dimer and utilizes the 2-fold symmetry of the space group, resulting in one subunit per asymmetric unit.

Escherichia coli↗

PubMed1987

Crystallization and preliminary X-ray investigation of uridine phosphorylase from Escherichia coli.

Crystals of uridine phosphorylase from Escherichia coli K12 have been grown from solutions of polyethylene glycol 4000. The crystals are trigonal, space group R3; the hexagonal axes are a = 154.4 A and c = 49.4 A. The crystals are quite stable to x-rays and diffract beyond 2.6 A resolution. It appears that the molecule is a hexamer with a subunit molecular weight of 27,500 and utilizes the 3-fold symmetry of the space group, resulting in two subunits/asymmetric unit.

Crystallization↗

PubMed1986

Aldehyde oxidase from rabbit liver: specificity toward purines and their analogs.

Aldehyde oxidase (EC 1.2.3.1) plays a role in the oxidation of aromatic heterocyclic compounds ingested by some higher vertebrates. To better understand this function, the specificity of the rabbit liver enzyme toward purines and their analogs was quantitatively studied. The chemical nature of the 6-substituent of purine markedly influenced substrate efficiency (Vmax/Km). Substituents that were hydrophobic were generally favorable. There was a correlation between the degree of hydrophobicity and the tightness of binding. 6-Substituents that were strongly electron-withdrawing also enhanced substrate efficiency. 6-Hydroxy and 6-amino substituents virtually obliterated substrate activity. In contrast, 2-hydroxypurine and 2-aminopurine were efficiently oxidized. 2,6-Disubstitution of purine was much less favorable than either 2- or 6-monosubstitution. N-Substitution of purines enhanced substrate efficiency in many cases. The typical order of preference for 9-substituents was 2'-deoxyribofuranosyl greater than ribofuranosyl greater than arabinofuranosyl greater than H. Acyclic nucleosides (9-[(hydroxy-alkyloxy)methyl]purines) were usually more efficient substrates than were 2'-deoxyribonucleosides. The kinetic constants of a variety of purine analogs revealed that the pyrimidine portion of the purine ring system was a more important determinant of substrate activity than the imidazole portion. The efficient oxidation of a variety of nucleosides suggests that detoxification of naturally occurring nucleoside analogs might be an important aspect of the physiological role of this enzyme. Overall, the data presented serve as a guide for predicting the susceptibility of heterocycles to oxidation by this enzyme.

Aldehyde Oxidase↗

PubMed1986

Human and bovine xanthine oxidases. Inhibition studies with oxipurinol.

Oxipurinol inhibited human xanthine oxidase and bovine xanthine oxidases by very similar mechanisms. It bound to an electronically reduced form of human xanthine oxidase in a manner similar to that previously discerned from its interactions with the bovine enzyme [review article: Spector, Biochem. Pharmac. 26, 355 (1977)]. Xanthine was a good source for the reducing equivalents because it did not compete with oxipurinol for binding to reduced enzyme. The inhibition of the rate of urate production progressively increased with time. Studies of the effect of the concentration of oxipurinol on the rate constant of the development of this inhibition revealed that a complex was rapidly formed between oxipurinol and reduced bovine or human xanthine oxidases (KD of about 8 microM). At 37 degrees these complexes were converted to stable complexes at a maximum rate of about 1.6 min-1. The rate constant was highly temperature dependent with an energy of activation of 30 kcal/mole (cf. 13 kcal/mole for the energy of activation for catalysis). These data support the earlier conclusions that the formation of stable complexes probably reflects a massive rearrangement of the initial complexes. The isolated oxipurinol-xanthine oxidase complexes spontaneously reverted to active enzyme with a rate constant of 0.02 min-1 at 37 degrees. The energy of activation for the "reactivation" was similar to that for the formation of the stable complexes. The rates of "reactivation" could be stimulated by high concentrations of xanthine: 2.4-fold at 50 microM and 3.4-fold at 100 microM. The constant for the overall inhibition by oxipurinol was approximately 100 nM with both enzymes.

Animals↗