A three year review on surgical treatment of tubo-ovarian abscess.

The authors made a 3-year retrospective study of cases of tubo-ovarian abscess surgically treated in KK Women's and Children's Hospital. In the period studied (1998 through 2000), there were 36 such cases. A total of 11 patients underwent laparoscopic treatment while 25 patients underwent laparotomy. The study demonstrates the differences in the patient profile and the short term morbidity in each mode of surgical treatment and the changing trends in the surgical treatment of tubo-ovarian abscess.

Neurological outcome prediction in a cardiorespiratory arrest survivor.

Outcome prediction of neurological recovery in an unconscious survivor of cardiorespiratory arrest is difficult and uncertain. We describe the case of a 25-yr-old post-arrest survivor who made a remarkable neurological improvement despite a seemingly hopeless prognosis. Conventional clinical and neurophysiological assessments need to be interpreted with care in the presence of uncontrolled seizure activity and sedative medications. The measurement of biochemical markers in the serum and cerebrospinal fluid may be useful in helping the clinician to arrive at a more accurate neurological outcome prediction.

Protection against human immunodeficiency virus type 1 infection in persons with repeated exposure: evidence for T cell immunity in the absence of inherited CCR5 coreceptor defects.

It has been hypothesized that protection against human immunodeficiency virus (HIV)-1 infection may result from either acquired host immunity, inheritance of a dysfunctional CCR5 HIV-1 coreceptor, or a low or attenuated virus inoculum. Thirty-seven HIV-1-uninfected persons engaging in repeated high-risk sexual activity with an HIV-1-infected partner were prospectively studied to determine the contribution of these factors in protecting against HIV-1 transmission. More than one-third (13/36) demonstrated HIV-1-specific cytotoxicity, and this activity significantly correlated with the wild type CCR5 genotype (P=.03). Only 1 subject (3%) demonstrated the homozygous CCR5 32-bp deletion (Delta32/Delta32). Median plasma HIV-1 RNA levels from 18 HIV-1-infected sex partners were not statistically different from those of matched infected control patients. These results indicate that inheritance of the Delta32 CCR5 mutation does not account for the majority of persistently HIV-1-resistant cases, and the presence of cellular immunity in these persons suggests either undetected infection or protective immunity.

HIV-1 Vpr increases viral expression by manipulation of the cell cycle: a mechanism for selection of Vpr in vivo.

The human immunodeficiency virus type 1 (HIV-1) encodes a protein, called Vpr, that prevents proliferation of infected cells by arresting them in G2 of the cell cycle. This Vpr-mediated cell-cycle arrest is also conserved among highly divergent simian immunodeficiency viruses, suggesting an important role in the virus life cycle. However, it has been unclear how this could be a selective advantage for the virus. Here we provide evidence that expression of the viral genome is optimal in the G2 phase of the cell cycle, and that Vpr increases virus production by delaying cells at the point of the cell cycle where the long terminal repeat (LTR) is most active. Although Vpr is selected against when virus is adapted to tissue culture, we show that selection for Vpr function in vivo occurs in both humans and chimpanzees infected with HIV-1. These results suggest a novel mechanism for maximizing virus production in the face of rapid killing of infected target cells.

Indicator cell lines for detection of primary strains of human and simian immunodeficiency viruses.

CCR5 and CXCR4 are the two major coreceptors that have been identified for human immunodeficiency virus (HIV) entry. We have modified several beta-galactosidase-based HIV indicator cell lines to express CCR5 and/or CXCR4. Using these new reagents, we have been able to detect all primary isolates tested using one or both of these cell lines. However, there is large variation in the absolute viral infectivity among primary strains. Furthermore, all HIV strains are capable of causing syncytia in the indicator cells when the coreceptor is present regardless of whether they had previously been characterized as "syncytia-inducing" or "non-syncytium-inducing."

Inhibition of human immunodeficiency virus syncytium formation and virus replication by castanospermine.

Castanospermine (1,6,7,8-tetrahydroxyoctahydroindolizine) is a plant alkaloid that modifies glycosylation by inhibiting alpha-glucosidase I. Castanospermine is shown to inhibit syncytium formation induced by the envelope glycoprotein of the human immunodeficiency virus and to inhibit viral replication. The decrease in syncytium formation in the presence of castanospermine can be attributed to inhibition of processing of the envelope precursor protein gp160, with resultant decreased cell surface expression of the mature envelope glycoprotein gp120. In addition, castanospermine may cause defects in steps involved in membrane fusion after binding of CD4 antigen. The antiviral effects of castanospermine may be due to modifications of the envelope glycoprotein that affect the ability of the virus to enter cells after attachment to the CD4 cell receptor.

Functional regions of the envelope glycoprotein of human immunodeficiency virus type 1.

The envelope of the human immunodeficiency virus type 1 (HIV-1) plays a central role in the process of virus entry into the host cell and in the cytopathicity of the virus for lymphocytes bearing the CD4 molecule. Mutations that affect the ability of the envelope glycoprotein to form syncytia in CD4+ cells can be divided into five groups: those that decrease the binding of the envelope protein to the CD4 molecule, those that prevent a post-binding fusion reaction, those that disrupt the anchorage of the envelope glycoprotein in the membrane, those that affect the association of the two subunits of the envelope glycoprotein, and those that affect post-translational proteolytic processing of the envelope precursor protein. These findings provide a functional model of the HIV envelope glycoprotein.

Expression of the art gene protein of human T-lymphotropic virus type III (HTLV-III/LAV) in bacteria.

Human T-lymphotropic virus type III (HTLV-III/LAV or HIV) contains a gene designated art (anti-repressor transactivator). Here, we report the expression of the art gene product in bacteria and show that the 20-kilodalton (kDa) bacterially expressed art protein is recognized by serum of a patient. The bacterially synthesized art protein competed in an immunological reaction with a 20-kDa protein produced in HTLV-III/LAV-infected lymphocytes. Antiserum to a synthetic oligopeptide corresponding to a sequence in the second exon of the art gene also precipitated the 20-kDa protein in HTLV-III/LAV-infected cells. These results demonstrate that the 20-kDa art gene product is expressed in cell lines that produce HTLV-III/LAV virions.

Role of the HTLV-III/LAV envelope in syncytium formation and cytopathicity.

Acquired immune deficiency syndrome (AIDS) is characterized by marked depletion of the T4+ helper subset of T cells. The aetiological agent of the disease, the human T-lymphotropic virus type III (HTLV-III)/lymphadenopathy-associated virus (LAV), specifically kills T4+ cells in vitro. Part of this specificity for the T4+ population residues in the relative efficiency with which HTLV-III infects these cells, as a result of a specific interaction between the T4 molecule and the virus envelope glycoprotein. In addition, the cytotoxic consequences of HTLV-III replication are dependent on cell type, as certain lymphoid and myeloid cells can be productively infected without notable cytopathic effect. Here we investigate the basis for the specific cytotoxicity of the virus, and report that high-level expression of the HTLV-III envelope gene induces syncytia and concomitant cell death in T4+ cell lines but not in a B-lymphocyte line. Syncytium formation depends on the interaction of envelope-expressing cells with neighbouring cells bearing surface T4 molecules. These results explain, at least in part, the specific cytopathic effect of HTLV-III infections.

Identification of a protein encoded by the trans activator gene tatIII of human T-cell lymphotropic retrovirus type III.

The human T-cell lymphotropic virus type III (HTLV-III/LAV) is a retrovirus associated with acquired immune deficiency syndrome. The region on the viral genome that is necessary for trans-activation of the HTLV-III/LAV long terminal repeat called tatIII has previously been determined to lie between nucleotides 5365 and 5607. Here we report that a bacterial fusion protein containing amino acid sequences specified by the first coding exon of the tatIII gene is recognized by some patient antisera. We also demonstrate that lymphoid and epithelial cells that express the trans activator function express a 14-kilodalton (kDa) protein recognized by a patient antiserum that reacts with the bacterial tatIII fusion protein. Cells transiently transfected with a deletion mutant of the trans activator protein produce a 12-kDa protein rather than the 14-kDa protein. These observations indicate that the tatIII region contains a functional gene and is capable of expressing a protein that migrates with an apparent molecular size of 14 kDa in some lymphoid and epithelial cells transfected with plasmids containing the tatIII region. We propose that the product of the trans activator gene be designated p14tat-III.

Trans-activator gene of HTLV-II induces IL-2 receptor and IL-2 cellular gene expression.

The human T-lymphotropic viruses types I and II (HTLV-I and -II) have been etiologically linked with certain T-cell leukemias and lymphomas that characteristically display membrane receptors for interleukin-2. The relation of these viruses to this growth factor receptor has remained unexplained. It is demonstrated here that introduction of the trans-activator (tat) gene of HTLV-II into the Jurkat T-lymphoid cell line results in the induction of both interleukin-2 receptor and interleukin-2 gene expression. The coexpression of these cellular genes may play a role in the altering T-cell growth following retroviral infection.

A second post-transcriptional trans-activator gene required for HTLV-III replication.

Evidence is provided for the existence of a seventh gene in the genome of human T-lymphotropic virus type III/lymphadenopathy-associated virus. The gene is necessary for replication and acts post-transcriptionally to relieve negative regulation of the messenger RNA for the virion capsid and envelope proteins. These observations suggest mechanisms for regulating both the latent and lytic phases of the virus life cycle.

Replicative and cytopathic potential of HTLV-III/LAV with sor gene deletions.

The genome of the human T-lymphotropic virus type III (HTLV-III/LAV) has the potential to encode at least three polypeptides in addition to those encoded by the gag, pol, and env genes. In this study, the product of the sor (short open reading frame) region, which overlaps the 3' end of the pol gene, was found to be a protein with a molecular weight of 23,000. An assay was developed for testing the ability of cloned HTLV-III proviruses to produce viruses cytopathic for T4+ lymphocytes. In the cell line used, C8166, neither the HTLV-III sor gene product nor the complete 3'-orf gene product were necessary for the replication or cytopathic effects of the HTLV-III.

The trans-activator gene of the human T cell lymphotropic virus type III is required for replication.

The trans-activator gene (tat-III) of the human T lymphotropic virus type III (HTLV-III/LAV) is shown to regulate positively the expression of viral proteins. Viruses in which the tat-III gene is deleted are incapable of prolific replication and do not demonstrate cytopathic effects in T4+ cell lines. These defects can be fully complemented in cell lines that constitutively express the tat-III gene product. We conclude that the tat-III gene product is required for efficient replication of HTLV-III in T4+ cells, and for that reason is important for the cytopathic effects of virus infection. These observations predict that inhibitors of the tat-III gene product may constitute effective therapeutic agents.

Post-transcriptional regulation accounts for the trans-activation of the human T-lymphotropic virus type III.

The level of synthesis of viral proteins and heterologous proteins under the control of long terminal repeat sequences of human T-lymphotropic virus type III (HTLV-III or LAV) increases dramatically in cells that constitutively express the HTLV-III trans-activator protein. Increased levels of protein synthesis occur without a comparable increase in the levels of corresponding messenger RNA. We propose that post-transcriptional events mediated by the HTLV-III trans-activator protein account for positive regulation of HTLV-III gene products in infected cells.

trans-Activation of the human T-cell leukemia virus long terminal repeat correlates with expression of the x-lor protein.

Cell lines established directly from adult T-cell leukemia-lymphoma patients or immortalized by human T-cell leukemia virus type I (HTLV-I) in vitro that do not produce complete HTLV virions were characterized both for the content of viral proteins and for the presence of trans-acting factors activating gene expression under the control of the HTLV long terminal repeat. The expression of the 42-kilodalton HTLV x-lor product correlated with trans-activation of the long terminal repeat. The implications of this study for understanding the role of the HTLV x-lor product in the initiation and maintenance of T-lymphocyte transformation are discussed.

Expression of the x-lor gene of human T-cell leukemia virus I in Escherichia coli.

The 3'-terminal regions of the human T-cell leukemia virus I (HTLV-I) and HTLV-II genomes encode a novel gene product. We showed that expression of this region fused to the beta-galactosidase gene in bacteria produces a protein recognized by adult T-cell leukemia-lymphoma patient sera. Rabbit antibodies raised against this protein specifically precipitated the 42-kilodalton x-lor gene protein from HTLV-I-infected cells.

A transcriptional activator protein encoded by the x-lor region of the human T-cell leukemia virus.

Human T-cell leukemia viruses type I and II (HTLV-I and -II) exhibit several features characteristic of this retroviral family: the presence of an x-lor gene encoding a nuclear protein, transformation properties suggesting the involvement of a virus-associated trans-acting factor, and transcriptional trans-activation of the long terminal repeat (LTR) in infected cells. In the study described here the HTL x-lor products, in the absence of other viral proteins, were able to activate gene expression in trans directed by HTLV LTR. The regulation of the expression of particular genes in trans by HTLV x-lor products suggests that they play a role in viral replication and possibly in transformation of T lymphocytes.

Subcellular localization of the product of the long open reading frame of human T-cell leukemia virus type I.

Human T-cell leukemia virus type I (HTLV-I) is a retrovirus associated with adult T-cell leukemia and lymphoma. In addition to containing the gag, pol, and env genes of the chronic leukemia viruses, the genome of HTLV-I contains a long open reading frame (LOR) located between the 3' end of the envelope gene and the 3' long terminal repeat sequence (LTR). It has been suggested that a protein of 42 kilodaltons that is encoded by the LOR region may participate in both trans-acting transcriptional regulation of the viral LTR as well as in the transforming properties of HTLV-I. It is reported here that a significant fraction of the 42-kilodalton HTLV LOR product is located in the nucleus of HTLV-I-infected transformed lymphocytes, a finding that is consistent with its proposed functions.