Head and neck squamous cell carcinoma and its correlation with human papillomavirus in people living with HIV: a systematic review

Over the last 20 years we assisted to an increase in the mean age of People Living with HIV and their comorbidities. Especially, there was an increase in Human Papillomavirus-related head and neck squamous cell carcinomas. Despite their increasing incidence in HIV-positive people, mechanisms that lead to their development and progression are only partially understood. The aim of this review is to identify key data and factors about HPV-related head and neck squamous cell carcinoma in HIV-seropositive patients. Systematic search and review of the relevant literature-peer-reviewed and grey-was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. We included in our review only the 35 full-text articles we considered the most substantial. It is mandatory to improve our knowledge about the interactions existing between HPV and HIV, and about their actions on oral mucosa immune system.

A humanized form of a CD4-specific monoclonal antibody exhibits decreased antigenicity and prolonged plasma half-life in rhesus monkeys while retaining its unique biological and antiviral properties

Certain monoclonal antibodies (MAbs) directed against CD4 can efficiently block HIV-1 replication in vitro. To explore CD4-directed passive immunotherapy for prevention or treatment of AIDS virus infection, we previously examined the biological activity of a nondepleting CD4-specific murine MAb, mu5A8. This MAb, specific for domain 2 of CD4, blocks HIV-1 replication at a post-gp120-CD4 binding step. When administered to normal rhesus monkeys, all CD4+ target cells were coated with antibody, yet no cell clearance or measurable immunosuppression occurred. However, strong anti-mouse Ig responses rapidly developed in all monkeys. In the present study, we report a successfully humanized form of mu5A8 (hu5A8) that retains binding to both human and monkey CD4 and anti-AIDS virus activity. When administered intravenously to normal rhesus monkeys, hu5A8 bound to all target CD4+ cells without depletion and showed a significantly longer plasma half-life than mu5A8. Nevertheless, an anti-hu5A8 response directed predominantly against V region determinants did eventually appear within 2 to 4 weeks in most animals. However, when hu5A8 was administered to rhesus monkeys chronically infected with the simian immunodeficiency virus of macaques, anti-hu5A8 antibodies were not detected. Repeated administration of hu5A8 in these animals resulted in sustained plasma levels and CD4+ cell coating with humanized antibody for 6 weeks. These studies demonstrate the feasibility of chronic administration of CD4-specific MAb as a potential means of treating or preventing HIV-1 infection.

Vascular cell adhesion molecule (VCAM)-Ig fusion protein defines distinct affinity states of the very late antigen-4 (VLA-4) receptor

The Very Late Antigen-4 receptor (VLA-4) (alpha 4 beta 1) is constitutively expressed on leukocytes and plays a role in cell trafficking, activation and development through its interaction with two alternative ligands, Vascular Cell Adhesion Molecule (VCAM-1) and fibronectin (FN). VLA-4-dependent cell adhesion is augmented by various stimuli, such as divalent cations, certain beta 1-specific monoclonal antibodies (mAbs) and cell activation. However, the steps of the adhesive process which they affect are currently undefined. In order to investigate whether or not these stimuli affect the primary step, VLA-4/ligand binding, we employed a recombinant VCAM-IgG fusion protein (VCAM-Ig) as a soluble ligand for VLA-4. Using this soluble ligand, we have directly demonstrated that the VLA-4 receptor can exist in at least three different affinity states on the cell surface. Two distinct high affinity states are induced on normal peripheral blood T cells, one by the anti-beta 1 mAb TS2/16, and one of 15-20 fold higher affinity by the divalent cation Mn2+. Interestingly, activation through the T cell receptor (TcR), through CD31 or by the Macrophage Inflammatory Protein-1 beta chemokine (MIP-1 beta) do not detectably increase VLA-4 affinity although they do augment VLA-4 dependent cell adhesion in vitro. Thus, VCAM-Ig binding defines high affinity VLA-4 receptors, revealing unique effects of the TS2/16 mAb and Mn2+ cations in vitro, and distinguishes VLA-4/VCAM interactions from subsequent steps in cell adhesion.

[Human infection by Hantavirus in southern and southeastern Brazil]

The results of serological investigation on Hantavírus antibodies carried out between February 1986 and August 1990 in human populations of the States of São Paulo and Paraná, Brazil, which had close contact with urban rats or wild rodents and others small mammals are described. OBJECTIVE--To identify the human infection caused by Hantavíruses, which are the etiological agents of Hemorrhagic fever with renal syndrome. METHODS--Sera from 1063 persons were tested by enzyme immunoassay (ELISA) to Hantaan, Seoul and Puumala antigens. Plaque reduction neutralization test to the same antigens and indirect immunofluorescent test to Hantaan antigen were performed in the positive sera. RESULTS--Antibodies to Hantaan, Seoul or Puumala viruses were detected in 32 persons by enzyme immunoassay (ELISA) and immunofluorescent test. Plaque reduction neutralization test performed in these 32 sera were positive in 5 (3 for Puumala and 2 for Seoul viruses). One serum reacted with high titer to Seoul virus in all tests. It was from a male resident in the rural area of Ribeira Valley, State of São Paulo, where he was born and has always lived. He had only travelled inside the State of São Paulo. CONCLUSION--There are serological evidences of Hantavírus infections in residents of the rural areas of the Amparo Island, Paranaguá Bay, State of Paraná and the Ribeira Valley, State of São Paulo; in employees of the port of Paranaguá, State of Paraná and in patients of the Emílio Ribas Hospital, São Paulo, State of São Paulo, who had a presumptive diagnosis of leptospirosis.

Continuous wave dye-laser technique for simultaneous, spatially resolved measurements of temperature, pressure, and velocity of NO in an underexpanded free jet

Gas dynamic quantities within an underexpanded nitrogen free jet, seeded with 0.5% NO, were measured nonintrusively by using an intracavity-doubled, rapid-tuning, cw ring dye laser. The UV beam passed obliquely through the jet axis, and its frequency repetitively scanned across adjacent rotational lines in the NO gamma band near 225 nm at a rate of 4 kHz. Spatially resolved excitation scans were obtained by monitoring the induced broadband fluoresence. Modeling the Doppler-shifted excitation scans with Voigt profiles permitted simultaneous determinations of NO velocity, rotational temperature, and pressure. Zero Doppler shift was referenced to an absorption trace obtained across a static cell and recorded concurrently with the excitation scan. Typically, the measured and predicted axial distributions agreed within 10%. At high Mach numbers there was evidence of rotational freezing of NO.

Specific interaction of lymphocyte function-associated antigen 3 with CD2 can inhibit T cell responses

Accessory cell surface molecules, such as T cell antigen CD2 and its ligand lymphocyte function-associated antigen 3 (LFA-3; CD58), are critical costimulatory pathways for optimal T cell activation in response to antigens. Interaction of CD2 with cell surface LFA-3 not only increases T cell/accessory cell adhesion, but also induces signal transduction events involved in the regulation of T cell responses. In this report, we show that specific interactions of LFA-3 with CD2 can result in T cell unresponsiveness to antigenic or mitogenic stimuli in vitro. By deletion of certain regions of the extracellular domain of LFA-3, we localized the CD2 binding site to the first domain of LFA-3. We then demonstrated that a soluble, purified first domain-LFA-3/IgG1 fusion protein (LFA3TIP) interacts with CD2 and binds to the same CD2 epitope as purified multimeric or cell surface-expressed LFA-3. LFA3TIP inhibits tetanus toxoid, hepatitis B surface antigen, anti-CD3 mAb, Con A, and phytohemagglutinin P-induced T cell proliferation, as well as xenogeneic and allogeneic mixed lymphocyte reactions (MLR). Unlike anti-LFA-3 or anti-CD2 monoclonal antibodies (mAbs) which inhibit T cell responses by blocking LFA-3/CD2 binding, LFA3TIP is capable of rendering T cells unresponsive to antigenic stimuli in situations where T cell activation is independent of CD2/LFA-3 interactions. Furthermore, LFA3TIP, but not blocking anti-CD2 mAbs, is capable of inducing T cell unresponsiveness to secondary stimulation in allogeneic MLR. This inhibition of T cell responses by LFA3TIP occurs through a different mechanism from that of mAbs to LFA-3 or CD2.

Truncated variants of gp120 bind CD4 with high affinity and suggest a minimum CD4 binding region

The envelope glycoprotein, gp120, of human immunodeficiency virus type 1 (HIV-1) binds the cellular protein CD4 with high affinity. By deletion we show that 62 N- and 20 C-terminal residues along with the V1, V2 and V3 variable regions of gp 120 are unnecessary for CD4 binding. A 287 residue variant (ENV59), missing those 197 amino acids, binds to CD4 with high affinity. A polyclonal antibody failed to efficiently precipitate ENV59 which is consistent with the loss of immunodominant antigenic structures in the regions deleted. This suggests that ENV59 may have potential as an immunogen, able to elicit antibodies against more conserved regions of gp120. Additionally, complementing co-expressed gp120 fragments as well as a circularly permuted molecule bind CD4, and suggest either that the molecular termini are adjacent in the folded structure, or that an N-terminal region folds into the structure unconstrained by its method of attachment to the rest of the molecule.

Signaling by vascular cell adhesion molecule-1 (VCAM-1) through VLA-4 promotes CD3-dependent T cell proliferation

Vascular cell adhesion molecule, VCAM-1, is an adhesion molecule expressed on activated endothelium thought to play a role in leukocyte migration to sites of inflammation. VCAM-1 adheres to leukocytes through the VLA-4 integrin. Recombinant soluble VCAM-1 (rsVCAM) and anti-CD3 mAb OKT3 were utilized to address the role of the VCAM-1/VLA-4 pathway in antigen-dependent T cell activation. Monocyte-depleted T cells proliferated upon exposure to co-immobilized OKT3 and rsVCAM but to neither alone. In contrast, an anti-VLA-4 mAb HP1/2 failed to co-activate with OKT3, despite the fact that both rsVCAM and HP1/2 support T cell adhesion comparably. These data indicate that adhesive function is not sufficient for co-stimulatory activity. They also reveal that VCAM-1 may play a role in regulating T cell immune responses as well as migration in vivo.

Expression and functional characterization of a soluble form of endothelial-leukocyte adhesion molecule 1

Endothelial leukocyte adhesion molecule 1 (ELAM1) is a leukocyte adhesion molecule induced on human venular endothelium in vitro and in vivo by inflammatory stimuli. A truncated cDNA for ELAM1 has been constructed, stably expressed in Chinese hamster ovary cells, and the secreted recombinant soluble form of ELAM1 (rsELAM1) purified to homogeneity by immunoaffinity chromatography. rsELAM1, when immobilized on plastic, is fully functional as an adhesion protein, and selectively binds only cells known to bind cell-surface ELAM1 expressed on human endothelial cells, including the myelomonocytic cell line HL60 and the colon carcinoma cell line HT29. Immobilized rsELAM1 also binds human PMN, monocytes, NK cells, and T cells. T cell subset analyses indicate preferential binding of CD4+ T memory cells. However, rsELAM1 is only a weak inhibitor of ELAM1-mediated adhesion. rsELAM1 should prove valuable for the further study of the role of ELAM1 expressed on the vascular wall during the inflammatory response.

Expression and functional characterization of a soluble form of endothelial-leukocyte adhesion molecule 1

Endothelial leukocyte adhesion molecule 1 (ELAM1) is a leukocyte adhesion molecule induced on human venular endothelium in vitro and in vivo by inflammatory stimuli. A truncated cDNA for ELAM1 has been constructed, stably expressed in Chinese hamster ovary cells, and the secreted recombinant soluble form of ELAM1 (rsELAM1) purified to homogeneity by immunoaffinity chromatography. rsELAM1, when immobilized on plastic, is fully functional as an adhesion protein, and selectively binds only cells known to bind cell-surface ELAM1 expressed on human endothelial cells, including the myelomonocytic cell line HL60 and the colon carcinoma cell line HT29. Immobilized rsELAM1 also binds human PMN, monocytes, NK cells, and T cells. T cell subset analyses indicate preferential binding of CD4+ T memory cells. However, rsELAM1 is only a weak inhibitor of ELAM1-mediated adhesion. rsELAM1 should prove valuable for the further study of the role of ELAM1 expressed on the vascular wall during the inflammatory response.

[Recent occurrence of human infection by Rocio arbovirus in the Valley of Ribeira region]

The presence of IgM antibodies to Rocio in sera of two children from rural area of Ribeira Valley, Brazil, was detected by MAC-ELISA. This new arbovirus of the Flaviviridae family was responsible for an extensive encephalitis epidemic that occurred in the region in 1975-1977. Since 1980 no human disease caused by this virus has been diagnosed. An improvement on surveillance of Rocio infections and on the researches for virus identification in suspected vectors and reservoirs is necessary.

Evidence for the presence of substance P-like immunoreactivity in the human cerebellum

Preliminary results on the localization of substance P-like immunoreactivity in the human cerebellum are presented. Cerebella from newborn and adult subjects were examined. While only sporadic positive fibres were detected in the adult tissue, the immunoreactive material appeared more abundant in the cerebella from newborn subjects. Varicose and non-varicose fibres and dot-like nerve terminals were present with different density in various regions. The paucity of immunoreactive perikarya suggests that most of the cerebellar substance P-like immunoreactive material has an extrinsic origin.

A mammalian tRNAHis-containing antigen is recognized by the polymyositis-specific antibody anti-Jo-1

The mammalian cell antigen reactive with the autoantibody anti-Jo-1 has been shown to contain tRNAHis. The RNA sequence of this human and mouse cell tRNA was determined in a search for unusual features that might be related to antigenicity. The 5' terminal nucleotide is unique among other sequenced tRNAs in that it is a methylated guanine. The presence of the hypermodified base queuine, which occurs in the wobble position of the anticodon of tRNAHis from several species, was not detected in the tRNAHis immunoprecipitated by anti-Jo-1 from either human HeLa or mouse Friend erytholeukemia cell extracts. The binding of protein(s) appears to confer antigenicity on tRNAHis since either proteinase K treatment or phenol extraction resulted in the loss of immunoprecipitability. However, we have not succeeded in identifying an antigenic protein, and we find that the antigenic complex is not resolved from purified tRNAHis by Sephacryl S-200 column chromatography. Immunofluorescence studies indicate that the antigenic form of tRNAHis is located preferentially in the mammalian cell cytoplasm. The results presented here are discussed in light of an earlier report (1) on the nature of the Jo-1 antigen.

Antibodies from patients with connective tissue diseases bind specific subsets of cellular RNA-protein particles

We characterized the RNA-containing antigens precipitated by sera from 260 patients with positive antinuclear antibodies. 49 individuals, most of whom had systemic lupus erythematosus or Sjögren's syndrome, possessed antibodies that precipitated the previously identified RNP, Sm, Ro, and La antigens either singly or in combinations. These antigens, which are located on discrete sets of small nuclear or cytoplasmic RNA-protein particles, exhibited a number of antigenic interrelationships. One patient's serum recognized a new particle containing a small RNA which we have called Th; it also precipitated the Ro complexes. Other patients with systemic lupus erythematosus, hepatitis B virus infection, juvenile rheumatoid arthritis, myositis, and rheumatoid arthritis had antibodies that precipitated specific subsets of ribosomal RNA and transfer RNA. One patient's serum contained a monoclonal immunoglobulin G that precipitated ribosomes. Most of these antibodies identified antigenic determinants constituted at least in part of protein. The specificity of the proteins bound to particular cellular RNA, probably explains the exquisite precision with which antibodies from rheumatic disease patients discriminate among RNA subsets. Such sera should be useful probes for investigating specific roles that different RNA and RNA-protein complexes play in cellular metabolism.

Striking similarities are exhibited by two small Epstein-Barr virus-encoded ribonucleic acids and the adenovirus-associated ribonucleic acids VAI and VAII

The nucleotide sequence of the region of the Epstein-Barr virus genome that specifies two small ribonucleic acids (RNAs), EBER 1 and EBER 2, has been determined. Both of these RNAs are encoded by the right-hand 1,000 base pairs of the EcoRI J fragment of EBV deoxyribonucleic acid. EBER 1 is 166 (167) nucleotides long and EBER 2 is 172 +/- 1 nucleotides long; the heterogeneity resides at the 3' termini. The EBER genes are separated by 161 base pairs and are transcribed from the same deoxyribonucleic acid strand. In vitro, both EBER genes can be transcribed by RNA polymerase III; sequences homologous to previously identified RNA polymerase III intragenic transcription control regions are present. Striking similarities are therefore apparent both between the EBERs and the two adenovirus-associated RNAs, VAI and VAII, and between the regions of the two viral genomes that specify these small RNAs. We have shown that VAII RNA as well as VAI RNA and the EBERs exist in ribonucleoprotein complexes which are precipitable by anti-La antibodies associated with systemic lupus erythematosus. Finally, we have demonstrated that the binding of protein(s) from uninfected cells confers antigenicity on each of the four virus-encoded small RNAs.

Four T7 RNA polymerase promoters contain an identical 23 bp sequence

The DNA sequences of four promoters for the bacteriophage-specified T7 RNA polymerase have been determined. All four regions contain an identical 23 bp sequence 5' pTAATACGACTCACTATAGGGAG-A(oh) which includes the 17 bp prior to and the first 6 bp of the transcribed region. They are located at 46.5, 55, 57 and 87% on the standard T7 map, thereby corresponding to the in vitro T7 class III RNA species IIIa, IV, V and IIIb, respectively. The precise RNA initiation sites were determined by 5' terminal RNA sequence analysis of the transcripts synthesized from promoter-containing DNA fragments. The comparative properties of these promoters for the monomeric T7 RNA polymerase and those for the multimeric E. coli RNA polymerase are discussed.

Photocross-linking analysis of the contact surface of tRNA Met in complexes with Escherichia coli methionine:tRNA ligase

Photoinduced covalent cross-linking has been used to identify a common surface of four methionine-accepting tRNAs which interact specifically with the Escherichia coli methionine:tRNA ligase (EC 6.1.1.10). tRNA--ligase mixtures were irradiated, and the covalently linked complexes were isolated and digested with T1 RNase (Schimmel & Budzik, 1977). The fragments lost from the elution profile of the T1 RNase digest were considered to have been cross-linked to the protein and therefore in intimate contact with the enzyme. Only specific cognate tRNA--ligase pairs produce covalently linked complexes. The four substrate tRNAs used in this study have substantially different sequences, but all showed a common cross-linking pattern, supporting the view that the sites cross-linked to the enzyme reflect the functionally common contact surface rather than particularly photoreactivity regions of tRNA. The cross-linked contact surface is comprised of three regions: (1) the narrow groove of the anticodon stem and its extension into the anticodon loop; (2) the 3' terminal residues; and (3) the 3' side of the "T arm". Unlike previous studies with other tRNAs, the D arm is not involved and significant radiation damage is suffered by the tRNA which must be taken into account in the analysis. The results are consistent with and complement chemical modification studies [Schulman, L. H., & Pelka, H. (1977) Biochemistry 16, 4256].

Isolation and characterization of two methionine: tRNA ligases from wheat germ

Two methionine: tRNA ligases (here called ligase A and ligase B) with distinctly different enzymatic and molecular properties were isolated in homogenous form from extracts of raw wheat germ. Both the A and B enzyme are composed of single polypeptide chains of Mr 105000 and 70000 respectively. The smaller molecule (B) has been shown not to be a proteolytic fragment of the larger one (A). The catalytic properties of both the A and B enzymes have been established and the Mg2-dependent capacity to charge six purified methionine-accepting tRNAs have been compared to those of the methionine: tRNA ligases from Escherichia coli and bakers' yeast. The possible reasons for the presence of two methionine: tRNA ligases and their unusual monomeric nature are discussed.

An isomorphous heavy-atom derivative of crystaline formylmethionine transfer RNA

An isomorphous osmium derivative of crystalline yeast initiator transfer RNA has been prepared and interpreted to 6-angstrom resolution. The coordinates of the heavy atoms have been determined by Patterson and "direct" methods applied to the difference coefficients of the centric projections, followed by least-squares refinement. There is one dominant site per asymmetric unit, consistent with the finding by neutron-activation analysis that there is approximately one osmium atom per molecule of transfer RNA. The osmium derivative appears to be a normal substrate for enzymatic aminoacylation.