Search PubMed⌕ Search

Biomedical subjects

G M Shaw

Publications and source records attributed to G M Shaw.

At least 199 records · Page 11Linked to original sources
PubMed1987

Mechanism of leukemogenesis by human T-cell leukemia virus types I and II: role of the lor gene.

The human T-cell leukemia (HTLV) family of viruses now include two groups of transforming viruses (HTLV-I and HTLV-II) and one group of viruses with immunosuppressive activity but no apparent transforming ability (HTLV-III). Nucleotide sequence analysis of an HTLV-I provirus by Seiki et al [Proc Natl Acad Sci USA 1982: 6899-902] has revealed a distinct region of the genome located between env and the long terminal repeat sequences (LTR). Analysis of a variant of HTLV-I, called HTLV-Ib, which retains transforming ability, revealed a deletion in the 5' portion of this sequence that indicates that this portion of the sequence probably does not play an essential role in transformation. Hybridizations at varying stringencies show that at least a portion of this additional region of HTLV-I and -II is more highly conserved than most other regions of the genome. The DNA sequence of this HTLV-II region localizes the area of homology within the 1,000 base pairs just upstream of the LTR; the remainder of the region is not conserved. The conserved region includes a long open reading frame, is denoted lor, and has the coding capacity for a protein of at least 38 kilodaltons (kd). Studies of the transcriptional activity of the LTR sequences show that the rate of LTR-directed transcription is greatly augmented in HTLV-infected cells, a phenomenon called trans-acting transcriptional regulation. It is suggested that transformation of lymphocytes by HTLV-I or -II is mediated by action of HTLV-encoded trans-acting transcription factors on cellular genes that control the replication of lymphocytes.

Deltaretrovirus Infections↗
PubMed1986

Genetic variation in HTLV-III/LAV over time in patients with AIDS or at risk for AIDS.

In a study of genetic variation in the AIDS virus, HTLV-III/LAV, sequential virus isolates from persistently infected individuals were examined by Southern blot genomic analysis, molecular cloning, and nucleotide sequencing. Four to six virus isolates were obtained from each of three individuals over a 1-year or 2-year period. Changes were detected throughout the viral genomes and consisted of isolated and clustered nucleotide point mutations as well as short deletions or insertions. Results from genomic restriction mapping and nucleotide sequence comparisons indicated that viruses isolated sequentially had evolved in parallel from a common progenitor virus. The rate of evolution of HTLV-III/LAV was estimated to be at least 10(-3) nucleotide substitutions per site per year for the env gene and 10(-4) for the gag gene, values a millionfold greater than for most DNA genomes. Despite this relatively rapid rate of sequence divergence, virus isolates from any one patient were all much more related to each other than to viruses from other individuals. In view of the substantial heterogeneity among most independent HTLV-III/LAV isolates, the repeated isolation from a given individual of only highly related viruses raises the possibility that some type of interference mechanism may prevent simultaneous infection by more than one major genotypic form of the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Identification and characterization of conserved and variable regions in the envelope gene of HTLV-III/LAV, the retrovirus of AIDS.

To determine the extent and nature of genetic variation present in independent isolates of HTLV-III/LAV, the nucleotide sequences of the entire envelope gene and parts of gag and pol were determined for two AIDS viruses. The results indicated that variation throughout the viral genome is extensive and that the envelope gene in particular is most highly variable. Within the envelope, changes were most prevalent within the extracellular region where clustered nucleotide substitutions and deletions/insertions were evident. Based on predicted secondary protein structure and hydrophilicity, these hypervariable regions represent potential antigenic sites. In contrast to the hypervariable regions, other sequences in the extracellular envelope and the overall envelope structure (including 18 of 18 cysteine residues), as well as most of the transmembrane region, were highly conserved.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Characteristics of hazardous material spills from reporting systems in California.

Data on hazardous material releases that occurred between January 1, 1982 and September 30, 1983 in California were obtained from the California Highway Patrol (CHP) and the US Department of Transportation (DOT). The majority of incidents involved highway transport of hazardous materials, although some information was available on air, rail, and stationary facility releases. Vehicle accidents and failure of or damage to the container were the most frequent causes of releases. Proportionately more hazardous materials incidents occurred in early summer than at other times of the year, during weekdays, and daytime hours. The largest proportions of incidents involved the chemical categories of corrosives and fuels. Reported exposures and injuries to response personnel and other people at the scene were relatively few; no fatalities were reported. Few incidents were reported in both data sources, suggesting that the examination of only one data source would yield a gross underestimate of the total number of hazardous materials incidents in California. The lack of available denominator data limits the interpretation of the findings.

Accidents↗
PubMed1985

Genomic diversity of human T-lymphotropic virus type III (HTLV-III).

The DNA genomes of human T-lymphotropic virus type III (HTLV-III) isolated from 18 individuals with AIDS or who were at risk for AIDS were evaluated for evidence of variation. Although all of the 18 viral DNA's hybridized throughout their entire genomes to a full-length cloned probe of the original HTLV-III isolate, each of the 18 isolates showed a different restriction enzyme pattern. The number of restriction site differences between isolates ranged from only 1 site in 23 to at least 16 sites in 31. No particular viral genotype was associated with a particular disease state and 2 of the 18 patients had evidence of concurrent infection by more than one viral genotype. Propagation of three different viral isolates in vitro for up to 9 months did not lead to detectable changes in their restriction patterns. These findings indicate that different isolates of HTLV-III comprise a spectrum of highly related but distinguishable viruses and have important implications regarding the pathogenicity of HTLV-III and attempts to develop effective diagnostic, therapeutic, and preventive measures for this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1985

HTLV-III infection in brains of children and adults with AIDS encephalopathy.

Unexplained debilitating dementia or encephalopathy occurs frequently in adults and children with the acquired immune deficiency syndrome (AIDS). Brains from 15 individuals with AIDS and encephalopathy were examined by Southern analysis and in situ hybridization for the presence of human T-cell leukemia (lymphotropic) virus type III (HTLV-III), the virus believed to be the causative agent of AIDS. HTLV-III DNA was detected in the brains of five patients, and viral-specific RNA was detected in four of these. In view of these findings and the recent demonstration of morphologic and genetic relatedness between HTLV-III and visna virus, a lentivirus that causes a chronic degenerative neurologic disease in sheep, HTLV-III should be evaluated further as a possible cause of AIDS encephalopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Etiology of AIDS: biological and biochemical characteristics of HTLV-III.

The newly identified human HTLV-III virus, the etiologic agent for AIDS, shares many of the biological and physicochemical properties common to a family of retroviruses named human T-cell leukemia (lymphotropic) viruses, or HTLV. Because of the similarities, and because of the uniform nomenclature for human T-cell leukemia (lymphotropic) viruses adopted at the first Cold Spring Harbor Meeting on HTLV (19, 79), this newly discovered virus associated with AIDS as HTLV-III was named HTLV-III. Other investigators making independent isolations of virus have suggested naming the virus lymphadenopathy virus or LAV (3, 16), immunodeficiency associated virus or IADV (48), AIDS-related virus (41). Immunological and nucleic acid comparison has now demonstrated that these viruses are, not surprisingly, very similar to HTLV-III (55, 63, 78). In view of the wide range of disease manifestations caused by the virus, and previous discussions concerning a uniform nomenclature for human T-lymphotropic retroviruses, it would seem ill-advised to restrict the name of this virus to one clinical manifestation of one disease. The frequent isolation of HTLV-III from patients with AIDS and ARC, the detection of antibodies specific for HTLV-III in nearly all patients with these diseases and in a high proportion of individuals at risk, and finally its effect on cells in vitro, leaves little doubt that HTLV-III is causatively involved in the development of these diseases. This etiologic association is further strengthened by the detection of HTLV-III infection in many instances where a direct cause-and-effect association can be made, e.g., hemophiliacs and children with AIDS, and blood from HTLV-III infected donors and the otherwise normal recipients of this blood who subsequently develop AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Genomic diversity of the acquired immune deficiency syndrome virus HTLV-III: different viruses exhibit greatest divergence in their envelope genes.

Converging lines of research have linked human T-cell lymphotropic virus type III (HTLV-III) to the pathogenesis of the acquired immune deficiency syndrome. A characteristic feature of this virus is its genomic heterogeneity, which occurs to varying degrees in different viral isolates. To define further the nature and extent of these genomic changes, we compared the molecularly cloned genomes of two variant HTLV-III isolates by extensive restriction enzyme mapping and heteroduplex thermal melt analysis. Both viral isolates were found to be highly related to each other throughout their entire genomic complement, yet they differed markedly in their restriction enzyme maps. Electron microscopic heteroduplex analysis revealed several distinct regions of divergence located almost exclusively in the part of the genome that encodes the viral envelope gene. In vitro culture of one of these viruses over a period of 3 months did not result in any genomic changes as determined by restriction analysis of viral DNA. These results, as well as the recently published nucleotide sequences of other HTLV-III isolates, indicate that the most substantial variation among HTLV-III isolates is located in the envelope. These findings raise the possibility that viral isolates from different individuals could have important biological differences in their envelope antigens, a consideration relevant to ongoing attempts to develop a vaccine against HTLV-III.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Nucleotide sequence analysis of a variant human T-cell leukemia virus (HTLV-Ib) provirus with a deletion in pX-I.

A variant of human T-cell leukemia virus subgroup I (HTLV-I), designated HTLV-Ib, has been isolated from a transformed T-lymphocytic cell line established from a Zairian patient with adult T-cell lymphoma. A recombinant phage clone of the variant provirus, denoted lambda MC-1, hybridizes under high stringency to HTLV-I DNA probes, but 17 of 43 restriction enzyme sites differ from those of HTLV-I, 10 of them clustering within 1.5 kilobases in the env-pX region. Since this variant virus retains its capacity to transform T-cells in vitro, and since a pX product is suspected to be important in transformation, we have determined the nucleotide sequence of the entire pX region of this virus for comparison to the prototype HTLV-I. In addition, the region between the gag and pol genes, parts of the pol and env genes, and a portion of the U3 region of the long terminal repeat sequence were also analyzed. We noted 141 single-base-pair changes among 3,897 base pairs, which were relatively well distributed over those portions of the provirus that were examined. In addition, an 11-base-pair deletion was found which included the potential initiator ATG codon of the first open reading frame of pX (pX-I). The next potential initiator codon predicted by the sequence is followed by 10 codons and then a termination codon. An identical deletion was also demonstrated in the only provirus present in another cell line established from the same patient on a different occasion after transformation in vitro of normal human umbilical cord blood cells. These results indicate that pX-I is not required for transformation.

Amino Acid Sequence↗
PubMed1984

Molecular characterization of human T-cell leukemia (lymphotropic) virus type III in the acquired immune deficiency syndrome.

The human T-cell leukemia (lymphotropic) virus type III (HTLV-III) appears to be central to the causation of the acquired immune deficiency syndrome (AIDS). Two full-length integrated proviral DNA forms of HTLV-III have now been cloned and analyzed, and DNA sequences of the virus in cell lines and fresh tissues from patients with AIDS or AIDS-related complex (ARC) have been characterized. The results revealed that (i) HTLV-III is an exogenous human retrovirus, approximately 10 kilobases in length, that lacks nucleic acid sequences derived from normal human DNA; (ii) HTLV-III, unlike HTLV types I and II, shows substantial diversity in its genomic restriction enzyme cleavage pattern; (iii) HTLV-III persists in substantial amounts in cells as unintegrated linear DNA, an uncommon property that has been linked to the cytopathic effects of certain animal retroviruses; and (iv) HTLV-III viral DNA can be detected in low levels in fresh (primary) lymphoid tissue of a minority of patients with AIDS or ARC but appears not to be present in Kaposi's sarcoma tissue. These findings have important implications concerning the biological properties of HTLV-III and the pathophysiology of AIDS and Kaposi's sarcoma.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Molecular cloning and analysis of a new variant of human T-cell leukemia virus (HTLV-ib) from an African patient with adult T-cell leukemia-lymphoma.

We report the identification and characterization of a new variant of HTLV-I in an African patient with adult T-cell leukemia/lymphoma (ATL). Proviral sequences were detected by Southern blot analysis in three T-cell lines established from this patient's peripheral blood lymphocytes (PBL) and lymph-node cells. We molecularly cloned and analyzed proviruses from two of these cells lines, one established by direct culture of PBL and one established by co-cultivation of PBL with cord-blood T cells. These two HTLV clones contained full-length proviruses which were identical to each other in 44 out of 44 restriction enzyme sites. They were closely related to, but distinct from, the prototype HTLV-I, having divergence in their envelope and 5' pX regions and therefore represented a new variant of HTLV-I. We designated it as HTLV-Ib. Despite the genomic differences, however, HTLV-Ib retained its tropism for OKT4+ lymphocytes as well as its ability to initiate and maintain transformation of these cells. The finding of a variant of HTLV-I in this African ATL patient, along with the results of recent seroepidemiological studies, extends to the African continent the prevalence of HTLV-I associated malignancy previously identified in the Caribbean and Japan.

Adult↗
PubMed1984

Homology of genome of AIDS-associated virus with genomes of human T-cell leukemia viruses.

A T lymphotropic virus found in patients with the acquired immune deficiency syndrome (AIDS) or lymphadenopathy syndrome has been postulated to be the cause of AIDS. Immunological analysis of this retrovirus and its biological properties suggest that it is a member of the family of human T-lymphotropic retroviruses known as HTLV. Accordingly, it has been named HTLV-III. In the present report it is shown by nucleic acid hybridization that sequences of the genome of HTLV-III are homologous to the structural genes (gag, pol, and env) of both HTLV-I and HTLV-II and to a potential coding region called pX located between the env gene and the long terminal repeating sequence that is unique to the HTLV family of retroviruses.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Genomes of evolutionarily divergent members of the human T-cell leukemia virus family (HTLV-I and HTLV-II) are highly conserved, especially in pX.

Human T-cell leukemia virus (HTLV) is a family of related human T-lymphotropic retroviruses closely linked with certain human T-cell malignancies and associated with many cases of acquired immunodeficiency syndrome (AIDS). We isolated and molecularly cloned HTLV from patients with both types of clinical disorders and found by restriction endonuclease mapping and core and envelope protein analysis that at least two evolutionarily divergent viral subgroups exist, HTLV-I and HTLV-II. Previous studies have failed to detect significant nucleotide sequence homology between HTLV-I and HTLV-II even though these different members of the HTLV family share certain biologic properties such as T-cell tropism and transformation. To further test these viruses for conserved regions in their genomes, we examined hybridization between HTLV-I and HTLV-II by using Southern blotting and heteroduplex mapping at different melting points. These two techniques produced similar results, showing that HTLV-I and HTLV-II proviruses have, in fact, strongly conserved nucleotide sequences in the pX region and lesser although still substantial homology in the LTR, gag, pol, and env regions. These data provide experimental evidence that HTLV-II, like HTLV-I, contains pX sequences. Although the function of pX is unknown, its conservation in evolutionarily divergent human T-lymphotropic viruses implies a biologically important function. It is possible, but unproven, that pX could encode proteins involved in T-cell tropism, cell transformation, immune suppression, or other biologic actions characteristic of the HTLV family.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Human T-cell leukemia virus: its discovery and role in leukemogenesis and immunosuppression.

We have highlighted the events leading to the discovery of the first human RNA tumor virus and then reviewed what is currently known about its biology. From this, it is clear that we have only begun to appreciate the biologic diversity, the geographic distribution, and the disease spectrum of this family of human T-lymphotropic retroviruses which we collectively term HTLV. At a basic level, HTLV provides a unique opportunity to study in vitro and in vivo mechanisms of cell transformation. Given its close association with adult T-cell leukemia and its ability to efficiently immortalize primary cells in vitro, we believe that HTLV will very likely harbor clues to the biology of cell growth, differentiation, and transformation. At a more clinical level, the close association between HTLV and a malignancy of clonally expanded (HTLV-containing) mature T-cells argues strongly for a causal relationship, although the mechanism for such is currently unknown. It is likely that further study of the molecular and cellular biology of this virus will bring together these basic and clinical findings and elucidate, at least in part, one mechanism for human leukemogenesis. From a more speculative viewpoint, the role of HTLV in the pathogenesis of human disease appears even broader. As discussed in this chapter, there are indications that all subtypes of HTLV may produce immunosuppression both in vitro and in vivo, and there is now exciting new data to suggest that a novel member of this family of viruses, HTLV-III, is causally linked to the AIDS syndrome. Moreover, the possibility has been raised that the immunosuppressive properties of HTLV could predispose patients to non-T-cell malignancies as occurs in patients with AIDS or chemically induced immunosuppression. Finally, by employing the experimental strategies which were successful in isolating HTLV-I, HTLV-II, and HTLV-III, it may be possible in the future to identify still other human retroviruses.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Molecular characterization of human T-lymphotropic leukemia virus type III associated with the acquired immunodeficiency syndrome.

A T-lymphotropic retrovirus with cytopathic but not immortalizing activity has been isolated repeatedly from patients with acquired immune deficiency (AIDS) or lymphadenopathy syndrome (LAS) and successfully transmitted to a T-cell line (HT) for continuous production. Seroepidemiology data and the OKT4 tropism and cytopathogenicity of this virus indicate it is the etiological agent of AIDS. We have cloned HTLV-III genomes using three approaches: (1) cDNA clones were obtained from a cDNA plasmid library constructed from RNA of purified virions using oligo (dT) primers; (2) unintegrated provirus clones were obtained from Hirt supernatants of acutely infected H9 cells using virus from H9/HTLV-III; (3) clones of integrated provirus with flanking cellular sequences were obtained from a genomic DNA library of H9/HTLV-III. Analyses of these clones show that the HTLV-III genome is similar in size to those of HTLV-I and HTLV-II and contains a gene that functions as a transcriptional activator. Different isolates of HTLV-III display greater polymorphism than different isolates of HTLV-I among each other, possibly due to the highly replicative nature of HTLV-III. Viral sequences could be detected in fresh lymph node tissues of some AIDS patients, but even in the positive samples the number of infected cells is small (less than 1%). In both fresh tissues that are positive for viral sequences and HTLV-III infected cell lines, a substantial amount of unintegrated viral DNA is present in addition to integrated provirus. This is an unusual finding for retroviruses but may be significant in the cytopathicity of HTLV-III as has been proposed for some avain retroviruses.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Quantification of platelet-bound IgG by 125I-Staphylococcal protein A in immune thrombocytopenic purpura and other thrombocytopenic disorders.

In this report we describe the use of an 125I-Staphylococcal protein A (SPA) assay to measure platelet-bound IgG in the evaluation of 62 thrombocytopenic patients. Platelets from 150 normal subjects were found to bind 146 +/- 112 molecules of SPA per platelet (mean +/- 2 SD). Nineteen of 20 patients with untreated immune thrombocytopenia had platelet IgG values above this range, with 15 of 20 having values above 1,000 molecules of SPA per platelet. Patients with immune thrombocytopenic purpura by clinical criteria, but who had failed conventional therapy (corticosteroids or splenectomy), had a wide range of platelet IgG levels: 4 of 20 had normal values, 6 of 20 had minimally elevated levels in the range seen with nonimmune thrombocytopenia, and 10 of 20 had much higher values. Fifteen patients with thrombocytopenia of apparent nonimmune origin and 7 others with chronic stable thrombocytopenia of unknown etiology were found to have platelet IgG levels within or only slightly above the normal range. Because of its simplicity, accuracy, and clinical correlation, the 125I-SPA assay provides an important new approach for studying platelet IgG in thrombocytopenic states. The data obtained with this technique are similar to those found in immune hemolytic anemia and suggest that the platelet-bound IgG so measured has pathophysiologic relevance in immune thrombocytopenic purpura.

Adult↗
PubMed1983

Immune thrombocytopenic purpura. Use of a 125I-labeled antihuman IgG monoclonal antibody to quantify platelet-bound IgG.

We used a radiolabeled monoclonal antibody to the Fc portion of human IgG to measure platelet-bound IgG in 54 thrombocytopenic patients and in 48 normal controls. The control group had a mean (+/- 1 S.D.) of 169 +/- 79 IgG molecules bound per platelet--10 to 100 times lower than values generally reported with other assay techniques. Sixteen of 17 patients with untreated thrombocytopenic purpura considered to be of immune origin had values ranging from 790 to 13,095--levels well above those found in normal subjects and in patients with "nonimmune" thrombocytopenia (246 +/- 156). In a second group, consisting of 11 patients with "immune" thrombocytopenic purpura who did not respond to conventional therapy (corticosteroids or splenectomy), the values were quite divergent: two patients had levels in the normal range, three had levels in the range of subjects with nonimmune thrombocytopenia, and six had much higher levels. Measurement of platelet-bound IgG with this monoclonal-antibody technique can help differentiate between immune and nonimmune thrombocytopenias. Low platelet counts in patients who have immune thrombocytopenia according to clinical criteria but are resistant to therapy may be related to factors other than IgG antibody.

Adult↗