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N Ngo

Publications and source records attributed to N Ngo.

10 recordsLinked to original sources
PubMed2000

Decrease in immune activation in HIV-infected patients treated with highly active antiretroviral therapy correlates with the function of hematopoietic progenitor cells and the number of naive CD4+ cells.

This study was conducted to determine the impact of immune activation, cytokine production and apoptosis on the naive CD4+ cell count and the function of hematopoietic progenitor cells during the initial phase of highly active antiretroviral therapy (HAART). Blood samples from 11 HIV-infected patients were collected prior to HAART and after 4 and 12 weeks of therapy. Flow cytometry was used to determine the naive CD4+ count and activated T cells. The cloning efficiency of progenitor cells was determined using a colony-forming cells assay. Finally, apoptosis and cytokine production were determined. During the study period, the naive CD4+ count and the cloning efficiency increased significantly. Immune activation was found in HIV-infected patients and decreased during HAART. The level of immune activation correlated negatively with both the naive CD4+ count and the function of progenitor cells. A negative correlation was found between apoptosis and the naive CD4+ count. Alterations in cytokine production during HAART or correlation between cytokine production and the naive CD4+ count or the cloning efficiency of progenitor cells were not detected. In conclusion, immune activation in HIV-infected patients treated with HAART is inversely correlated with the function of progenitor cells and the naive CD4+ count.

Anti-HIV Agents↗
PubMed1999

Weak anti-HIV CD8(+) T-cell effector activity in HIV primary infection.

HIV-specific CD8(+) T cells play a major role in the control of virus during HIV primary infection (PI) but do not completely prevent viral replication. We used IFN-gamma enzyme-linked immunospot assay and intracellular staining to characterize the ex vivo CD8(+) T-cell responses to a large variety of HIV epitopic peptides in 24 subjects with early HIV PI. We observed HIV-specific responses in 71% of subjects. Gag and Nef peptides were more frequently recognized than Env and Pol peptides. The number of peptides recognized was low (median 2, range 0-6). In contrast, a much broader response was observed in 30 asymptomatic subjects with chronic infection: all were responders with a median of 5 peptides recognized (range 1-13). The frequency of HIV-specific CD8(+) T cells among PBMC for a given peptide was of the same order of magnitude in both groups. The proportion of HIV-specific CD8(+)CD28(-) terminally differentiated T cells was much lower in PI than at the chronic stage of infection. The weakness of the immune response during HIV PI could partially account for the failure to control HIV. These findings have potential importance for defining immunotherapeutic strategies and establishing the goals for effective vaccination.

Adult↗
PubMed1998

No evidence for proliferation in the blood CD4+ T-cell pool during HIV-1 infection and triple combination therapy.

OBJECTIVE: To evaluate the role of cell proliferation in peripheral blood lymphocyte (PBL) dynamics during HIV infection and potent antiretroviral therapy including protease inhibitors. DESIGN: Transverse study of 150 patients at different stages of infection. Longitudinal study of 50 patients on triple combination antiretroviral therapy with 9-month follow-up. METHODS: Ex vivo incubation of fresh PBL with the DNA biosynthetic marker bromodeoxyuridine (BrdU). Flow cytometric analysis of cell phenotypes and BrdU incorporation. Parallel determination of plasma virus load and CD4+ cell counts. RESULTS: Percentages of BrdU+ B and T lymphocytes found in patients with asymptomatic HIV infection were not different from the low values found in HIV-seronegative controls, and were not correlated with the CD4+ cell count. DNA synthesis increased significantly only during acute opportunistic infections occurring in patients with high plasma viral load and fewer than 100 x 10(6) CD4+ cells/l. Triple combination therapy induced a decrease of plasma virus load and a rise of CD4+ cell counts, whereas BrdU incorporation remained low or decreased. CONCLUSION: Proliferation of peripheral blood T cells observed at late stages of HIV infection corresponds to a response to opportunistic infections. Apart from these particular cases, proliferation in this compartment does not appear as a critical parameter of CD4+ cell kinetics during chronic HIV infection and potent therapy.

Anti-HIV Agents↗
PubMed1998

Acanthamoeba meningoencephalitis following autologous peripheral stem cell transplantation.

Amoebic meningoencephalitis is an unusual complication of bone marrow transplantation. We report a case of Acanthamoeba meningoencephalitis in a patient with non-Hodgkin's lymphoma after autologous stem cell transplantation. Leg weakness, fever and urinary retention developed 69 days following transplantation. The patient then developed fever, generalized tonic clonic seizure, rapid deterioration of mental functions and hypercapneic respiratory failure. Magnetic resonance imaging demonstrated a ring enhancing lesion at the level of the thoracic spines 11 and 12. Examination of the cerebrospinal fluid revealed pleocytosis. Despite empiric therapy with broad-spectrum antimicrobial agents, the patient's condition worsened and she died 11 days following admission. Autopsy findings revealed a subacute meningoencephalitis secondary to Acanthamoeba culbertsoni.

Acanthamoeba↗
PubMed1997

Deletions of the Aequorea victoria green fluorescent protein define the minimal domain required for fluorescence.

The Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria is a widely used marker for gene expression and protein localization studies. Dissection of the structure of the protein would be expected to shed light on its potential applications to other fields such as the detection of protease activity. Using deletion analysis, we have defined the minimal domain in GFP required for fluorescence to amino acids 7-229. This domain starts at the middle of the first small alpha helix at the N terminus of GFP and ends immediately following the last beta sheet. Studies of the amino acids at both termini of the minimal domain revealed that positions 6 and 7 at the N terminus are Glu-specific. Change of the Glu residues to other amino acids results in reduction of GFP fluorescence. Position 229 at the C terminus of GFP, however, is nonspecific: the Ile can be replaced with other amino acids with no measurable loss of fluorescence. A total of only 15 terminal amino acids can be deleted from GFP without disrupting fluorescence, consistent with findings of a previous study of GFP crystal structure (Ormo, M., Cubitt, A. B., Kallio, K., Gross, L. A., Tsien, R. Y., Remington, S. J. (1996) Science 273, 1392-1395 and Yang, F., Moss, L. G., and Phillips, G. N., Jr. (1996) Nat. Biotechnol. 14, 1246-1251) that a tightly packed structure exists in the protein. We also generated internal deletions within the loop regions of GFP according to its crystal structure and found that all such deletions eliminated GFP fluorescence.

Animals↗
PubMed1993

In vitro assembly of multiprotein complexes containing alpha, beta, and gamma tubulin, heat shock protein HSP70, and elongation factor 1 alpha.

We have isolated two sets of multiprotein complexes from supernatants from high-speed centrifugation of nocodazole-arrested CHO cells. One set, assembled in vitro after a 37 degrees C incubation in the presence of ATP or GTP, is composed of equivalent amounts of alpha- and beta-tubulin and a 50-kDa protein, provisionally identified as elongation factor 1 alpha. These complexes, which are heterogeneous in size when analyzed by sucrose gradient ultracentrifugation, also contain the cognate form of heat shock protein HSP70 and gamma-tubulin, a tubulin isoform of low abundance, along with other proteins known to be involved in the regulation of mitosis. Similar but distinct complexes assemble in vitro if the same extracts are incubated at 37 degrees C without added nucleotides; multiprotein complexes generated under these conditions lack HSP70 but contain instead a 43-kDa protein identified as an actin isoform. Both sets of assembled complexes exhibit a globular substructure when analyzed by electron microscopy, and their size distribution suggests that they assemble by the step-wise addition of smaller precursors. The properties of these multiprotein complexes and their presence in cells arrested in a stage between prophase and metaphase suggest that they may be precursors to mitotic centrosomes and are possibly involved in mitotic spindle nucleation.

Animals↗