Stabilization of HIV-1 gp120-CD4 receptor complex through targeted interchain disulfide exchange.

HIV-1 enters cells via interaction between the trimeric envelope (Env) glycoprotein gp120/gp41 and the host cell surface receptor molecule CD4. The requirement of CD4 for viral entry has rationalized the development of recombinant CD4-based proteins as competitive viral attachment inhibitors and immunotherapeutic agents. In this study, we describe a novel recombinant CD4 protein designed to bind gp120 through a targeted disulfide-exchange mechanism.

Development of e-Juba, a preliminary proof of concept unmanned aerial vehicle designed to facilitate the transportation of microbiological test samples from remote rural clinics to National Health Laboratory Service laboratories.

For students and academics within the field of Medical Microbiology and Infectious Diseases, it is readily apparent what an enormous professional contribution Professor Hendrik Koornhof has made to this critically important specialty, not only in Africa, but worldwide. For those outside of the specialty, his contributions as a thoroughly decent person and role model are no less evident. What emerges in both spheres is his clear commitment to the welfare of others, as opposed to himself.

Automated detection of malaria-associated intraleucocytic haemozoin by Cell-Dyn CD4000 depolarization analysis.

Laboratory tests for malaria are only performed if there is clinical suspicion of the disease, and a missed diagnosis contributes substantially to morbidity and mortality. Malaria parasites produce haemozoin, which is able to depolarize light and this allows the automated detection of malaria during routine complete blood count analysis (CBC) with some Abbott Cell-Dyn instruments. In this study, we evaluated the Cell-Dyn CD4000 with 831 blood samples submitted for malaria investigations.

Thrombocytopenia in patients with malaria: automated analysis of optical platelet counts and platelet clumps with the Cell Dyn CD4000 analyser.

Platelet counts and automated detection of platelet clumps were evaluated by optical analysis with the Abbott CD4000 analyser (Abbott Diagnostics, Santa Clara, CA, USA) in this South African study of 828 samples referred for malaria investigations. Based on microscopy (Micro) and rapid tests (RT) for HRP2 protein and parasite-associated LDH, malaria negative samples (n = 417) were defined as Micro-, RT-. Convalescent cases (n = 64) were Micro-, RT+ and had a recent record of positive microscopy.

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 and multiple myeloma in South Africa.

Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) has been implicated in the etiopathogenesis of multiple myeloma. Although the association is biologically plausible and attractive, conflicting data have been reported, including evidence against the involvement of KSHV in the pathogenesis of the disease. The purpose of this study was to determine the relationship between KSHV and myeloma in blacks in South Africa, in whom the disease is not uncommon and the seroprevalence of KSHV is higher than in the areas in which this association has been documented.

Systematic review of combination antiretroviral therapy with didanosine plus hydroxyurea: a partial solution to Africa's HIV/AIDS problem?

Effective antiretroviral therapy remains beyond the reach of most human immunodeficiency virus (HIV)-infected persons living in the third world because of its tremendous cost. The cancer drug, hydroxyurea, inhibits HIV-1 replication in vitro and, when combined with didanosine (ddI), results in significant antiretroviral synergy. In vivo, hydroxyurea specifically targets quiescent lymphocytes and macrophages, important cellular reservoirs for HIV-1, and the combination of ddI plus hydroxyurea effectively reduces plasma HIV-1 RNA levels.

Automated malaria detection by depolarization of laser light.

Anecdotal experience with full blood count (FBC) technology incorporating analysis of depolarized laser light (DLL) for the enumeration of eosinophils showed that malaria infection generated unusual distributions in the white cell channels. The objective of this study was to identify and define criteria for a diagnosis of malaria using this technology. To determine sensitivity, specificity, and positive and negative predictive values, 224 directed samples referred specifically for malaria were used; true positives were defined as those in which malaria was identified by microscopic and/or immunological methods.

CD4+ T cell enumeration in HIV infection with limited resources.

The incidence of human immunodeficiency virus (HIV) infection continues to increase in South Africa. Limited resources are available for diagnosis and management of the disease and the development of affordable strategies is required. Absolute CD4 counts are used locally predominantly to monitor disease progression and institute prophylaxis against opportunistic infections.

Field evaluation of a novel haemoglobin measuring device designed for use in a rural setting.

Objective: To evaluate the use of a robust, cheap method for haemoglobin estimation by non-laboratory-trained personnel in a rural setting.

Design: Comparative study.

Setting: Tintswalo Hospital, Acornhoek.

12p rearrangement and DNA amplification mapped by comparative genomic hybridization in a patient with secondary myeloid leukemia.

Rearrangements of the short arm of chromosome 12 (12p) are a common finding in hematologic malignancies. There has recently been considerable interest in chromosome 12 abnormalities in view of the mapping of the TEL gene to 12p13 and frequent 12p interstitial deletions. Overrepresentation of 12p sequences is, on the other hand, a consistent finding in testicular germ cell tumor (TGCT), and the 12p11.

Identification of endonuclease activity in HIV-1 gp120 preparations produced using baculovirus expression systems.

Experiments undertaken with commercially available recombinantly produced human immunodeficiency virus Type 1 (HIV-1) gp120 demonstrated that the resuspended lyophilized protein, a product of the baculovirus expression system, had intrinsic nuclease activity. This nuclease activity was distinguishable from the molecular-grade bovine serum albumin that it was constituted in. The activity was thermolabile in that if the preparation was heated to 100 degrees C for 10 min, the activity was abolished, although this did not happen when it was stored at -20 degrees C.

Evaluation of DNA analysis for evidence of apoptosis in megaloblastic anaemia.

This study involved DNA analysis of bone marrow cells of 15 patients with megaloblastic anaemia. The diagnosis was based on the morphological changes seen in the bone marrow, associated with either a low red cell folate or serum vitamin B12 level and an adequate response to appropriate therapy as confirmation of the diagnosis. Flow cytometric DNA analysis showed an increase in the S and G2 phases of the cell cycle, but conventional agarose gel electrophoretic DNA analysis did not confirm the characteristic 'ladder pattern' which might have been expected in classic apoptosis.

Protein synthesis inhibition is not a requisite for puromycin- and cycloheximide-induced c-myc mRNA superinduction.

The phenomenon of superinduction refers to the process by which high doses (30-180 microM) of the protein synthesis inhibitors Puromycin (PM) or Cycloheximide (CHX) augment and stabilize mRNA transcript levels through mechanisms which are dependent on the complete inhibition of protein synthesis. The current study undertaken in HL-60 leukaemic cells has dissociated the protein synthesis-inhibitory effects of PM and CHX from their c-myc mRNA superinducing effects. When employed at concentrations which were sub-inhibitory with respect to protein synthesis (0.

Glycophorin variants and Plasmodium falciparum: protective effect of the Dantu phenotype in vitro.

Experimental work was carried out to establish the growth characteristics of Plasmodium falciparum in an in vitro culture system using cells with the Dantu, Henshaw and S-s-U- blood-group variants. A flow cytometric technique, using the dye thiazole orange, was adapted for use on the Epics Profile II flow cytometer to count the parasites. This was performed at 24, 48 and 72 h.

Puromycin-elicited c-myc mRNA superinduction precedes apoptosis in HL-60 leukaemic cells.

The phenomenon of superinduction refers to the process by which high concentrations of protein synthesis inhibitors augment and stabilize mRNA transcript levels, e.g. 36-180 microM of Puromycin (PM) has been found to elicit c-myc mRNA superinduction.

C-myc expression is down-regulated in mafosfamide-treated HL-60 cells undergoing apoptosis.

The expression of the proto-oncogene c-myc has been strongly implicated in the regulation of apoptosis. Since we have previously shown apoptosis to occur in HL-60 leukemic cells exposed to the prodrug Mafosfamide (ASTA Z 7557), the present study was undertaken to examine the levels of c-myc mRNA transcripts in such cells. Mafosfamide, which is a cyclophosphamide derivative that rapidly generates 4-Hydroperoxycyclophosphamide after aqueous dissolution, was employed in doses ranging from 0.

Cell-cycle disruptions and apoptosis induced by the cyclophosphamide derivative mafosfamide.

The effect of the cyclophosphamide derivative mafosfamide (ASTA Z 7557) was investigated in vitro in HL60 leukemic cells. Mafosfamide, which rapidly generates 4-hydroxycyclophosphamide after aqueous dissolution, was employed at doses ranging from 0.1 to 10 micrograms/mL.

Substituted purines elicit differential cytokinetic, molecular and phenotypic effects in HL-60 cells.

This study investigated and compared the cytokinetic, phenotypic and molecular effects elicited in HL-60 human leukemic cells by low doses (0.6 microM) of 3 closely related, substituted purines, puromycin (PM), puromycin aminonucleoside (PAN) and 6-dimethylaminopurine (6-DMAP). PM, but not 6-DMAP or PAN, inhibited [14C]leucine incorporation, induced a time-related cytotoxic effect, a G2-arrest, a metaphase-mitotic-arrest, apoptosis and c-myc mRNA superinduction.

CD10 antigen density in childhood common acute lymphoblastic leukaemia: comparisons of race and sex.

During the 25 month period from July 1989 until August 1991, 58 children with FAB defined acute lymphoblastic leukaemia (ALL) were referred for immunophenotypic analysis. Of these, 42 children with a common/pre-B phenotype (CD19/CD10-positive) were studied specifically to assess CD10 antigen density. A pattern of segregation was found between males and females and between black and white children.

Unexpected cytokinetic effects induced by puromycin include a G2-arrest, a metaphase-mitotic-arrest, and apoptosis.

The potent effects of low doses of PM on the cell cycle have to date been obscured by the conventional usage of this drug at high concentrations (5-50 micrograms/ml) to inhibit protein synthesis. In this in vitro study undertaken in a variety of malignant and non-malignant human and murine cell types, we found that low doses of PM (0.1-0.