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. His modesty and self-effacing nature have endeared Hendrik to many generations of students, peers and others who have indeed been privileged to have benefited from knowing him and working with him. In his 50 years with the South African Institute for Medical Research, and subsequently with the National Health Laboratory Service, Hendrik Koornhof has been the ideal academic, who is not as concerned about receiving financial rewards, recognition, etc. as about contributing to scientific knowledge. Many of his contributions have been in guiding others by his words and his deeds, and as a result he has been rewarded in seeing the accomplishments of his students, many of whom have gone on to achieve greatness in diverse fields, both locally and abroad. As we reflect in this festschrift on Hendrik's many achievements over 80 years, we thank him for more than just his research and teaching contributions over half a century with the South African Institute for Medical Research and the National Health Laboratory Service. We thank him for showing us what a privilege it is to work in the world of academia. Although we are not microbiologists, we thank him for having inspired us with the will to address problems of service delivery in the fight against microbiological diseases, which constitute the overwhelming bulk of the burden of disease in the developing world, both in Africa and further afield.

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. Samples were categorized as malaria negative (n = 417), convalescent malaria (n = 64) or malaria positive (n = 350) by reference to thin/thick film microscopy, 'rapid test' procedures, polymerase chain reaction analysis and clinical history. With regard to CD4000 depolarization analysis, a malaria positive CD4000 pattern was ascribed to samples that showed one or more abnormal depolarizing purple events, which corresponded to monocytes containing ingested malaria pigment (haemozoin). Positive CD4000 patterns were observed in 11 of 417, 50 of 64 and 281 of 350 of malaria negative, convalescent malaria and malaria positive samples respectively. The specificity and positive predictive values for malaria (active and convalescent) were very high (97.4 and 96.8%, respectively), while sensitivity and negative predictive values were 80.0 and 83.0% respectively. Depolarization analysis was particularly effective for Plasmodium falciparum malaria but there was lower detection sensitivity for White compared with Black African patients. CD4000 90 degrees depolarization vs 0 degrees analysis revealed a proportion of samples with small nonleucocyte-associated depolarizing particles. Appearance of such events in the form of a discrete cluster was associated with P. vivax rather than P. falciparum infection.

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. Malaria positive cases were subdivided into Micro+ (n = 315) and Micro-, RT+, PCR+ (polymerase chain reaction) (n = 32) subgroups. The mean platelet count for Micro+ cases (89.7 x 10(9)/l) was significantly lower than both the malaria negative (mean 212.6 x 10(9)/l) and convalescent malaria (mean 152.8 x 10(9)/l) groups; 89% of microscopy positive cases were thrombocytopenic (< 150 x 10(9)/l) and 30% had severe thrombocytopenia (< 50 x 10(9)/l). For comparison, 32% of the 417 malaria negative samples were thrombocytopenic and 6% of these were severe. Two thirds of samples with parasitaemia above 10% had platelet counts of < 50 x 10(9)/l while the counts were largely independent of parasite numbers when the parasitaemia was below 10%. Thirty percent of samples with microscopically detectable parasites had a PltClmp flag compared to 13% of the malaria negative group but, when the actual platelet count was taken into account, it became apparent that appearance of the flag was primarily associated with thrombocytopenia per se rather than malaria status. In most samples with a PltClmp flag, the CD4000 optical platelet clump 'signature' was indicative of small platelet aggregates and giant platelets. Morphological examination confirmed the presence of varying numbers of small platelet aggregates (3-12 individual platelets), often together with increased giant platelets, in many samples with a PltClmp flag. The observations suggest that while patients with malaria may be predisposed to the development of thrombocytopenia, a reduced platelet count in some patients may also be due in part to pseudo-thrombocytopenia.

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. Using a nested polymerase chain reaction (PCR) assay, the authors initially tested for the presence of KSHV DNA sequences (KS330(233)) in bone marrow aspirates, bone marrow biopsy material, and cultured bone marrow adherent cell samples of patients with myeloma. KSHV DNA sequences were detected in 4 of 10 (40%) of the adherent cell cultures and 1 of 20 (5%) of the bone marrow aspirate samples. None of the bone marrow biopsy samples (0/9) or control bone marrow aspirate samples (0/19) was positive. To confirm the positive results in the bone marrow cultures noted above and to exclude contamination, the procedure was repeated in a further 7 patients with myeloma and 11 controls with lymphoproliferative disorders using the same nested PCR assay. In addition, the authors used a different set of primers that recognize sequences internal to the 233-bp fragment to yield a final product of 186 bp. The authors were unable to detect any KSHV DNA sequences in the patients with myeloma (0/7) or the control patients with other lymphoproliferative disorders (0/11). Taken together, the finding of a positive result in 4 of 17 patients (23.5%), which is similar to the background seroprevalence rate, does not support a clear association between myeloma and KSHV in blacks in South Africa.

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. Combination ddI-hydroxyurea costs about one-eighth as much as currently recommended triple drug combinations, and several countries in Africa are exploring the feasibility of widescale use of ddI-hydroxyurea for their HIV-infected populations. Intrigued by its potential relevance for Africa, the authors reviewed the literature on the in vitro and clinical efficacy of ddI plus hydroxyurea against HIV. The combination of ddI plus hydroxyurea is an effective and potentially more affordable regimen for HIV-infected persons living in poorer countries.

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. For the DLL method, positive was defined as one or more large mononuclear cell(s) for which the 90 degrees depolarized signal exceeded the 90 degrees polarized signal. To determine possible utility in a routine haematology laboratory setting, 220 random undirected FBC samples were evaluated for possible malaria infection by the DLL method. Of the 224 directed samples, 95 were malaria positive as determined by microscopic and/or immunological methods, and 129 were negative. For the DLL method, overall sensitivity was 72% (90% in the case of Black Africans), and specificity 96%. Positive and negative predictive values overall were 93% and 82% respectively. In the utility study a single positive result was identified among the 220 samples studied. This was found to be from a patient with malaria. The detection of unexpected malaria by automated screening FBC analysis could substantially lower the mortality and morbidity from unascertained infection, especially in indigenous African peoples.

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. A dramatic increase in demand for CD4 counts prompted an investigation for a more cost-effective flow cytometry method than those currently recommended by the Centers for Disease Control (CDC). CD4 counts generated by two different single tube methods using CD3/CD4/CD8 [1(3)] and CD4 [1(1)] antibodies, respectively, were compared to the CDC recommended 6 tube 2 colour panel [6(2)]. Whole blood analysis using the Coulter Multi-Q-Prep system and an Epics XL Flow Cytometer (Coulter, Hialeah, FL) was performed for each of the three methods. Random samples from HIV positive adult patients were compared. A mean difference in the absolute CD4 counts of less than 10x10(6)/l was generated by both of the alternative panels when compared with the 6(2) panel. The precision of the three methods is comparable. In reagents alone, the 1(3) and 1(1) methods represent a cost saving of 76% and 93%, respectively, over the 6(2) method. The 1(3) and 1(1) panels would permit more affordable CD4 counts to be determined by the gold standard methodology of flow cytometry with no clinically significant sacrifices in accuracy or precision.

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 12p11.2-p12.1 subregion has been found to be specifically involved. We have studied a secondary leukemic patient whose cells contained 12p rearrangements with a view to clarifying the underlying molecular events. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) have revealed the presence of 12p11 breakpoints on both 12 homologs as well as amplification of 12p11-p12-derived sequences. Six YACs and a cosmid probe have been used in an attempt to map the amplification unit on 12p. The two YACs contigs WC-1468 and WC-985 were not amplified, and our results suggested a small amplicon localized in the 12p11.2-p12 subregion. We speculate that this region harbors gene(s) which are critical in tumor formation and could be involved in both TGCT and our patient. Whether the same gene(s) are involved in both amplification and translocation is unknown.

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. The nuclease activity was also Ca+2- and Mg+2-dependent, and had endonuclease as opposed to exonuclease activity. Zn+2 ions were found to inhibit the enzyme. The intensity of nuclease activity varied from batch to batch. A lyophilized homogenate of Sf9 insect cells expressing the Rho baculovirus-derived red blood cell protein 4.2 (Pallidin) was also found to have nuclease activity on reconstitution. In contrast, most, though not all E. coli-produced recombinant proteins were found to be free of nuclease activity. The use of activity gels to identify the size of the nuclease contained in the gp120 preparation was limited, because despite the use of many renaturation methods, the enzyme in the gp120 preparation could not be functionally resuscitated following sodium dodecyl sulfate polyacrylamide gel electrophoresis. Immunoprecipitation studies were useful to demonstrate that nuclease activity in the gp120 preparation was functionally distinguishable from the gp120 itself. When mononuclear cells transformed with anti-CD3 were concurrently incubated with gp120 (5-40 micrograms/mL), internucleosomal DNA fragments characteristic of apoptosis were demonstrated in the supernatant by DNA gel electrophoresis. In the context of HIV-1 and AIDS, where the depletion of CD4+ T-cells has been found to be associated with apoptosis, nuclease activity intrinsic to the gp120 preparation used in experimentation may potentially alter experimental results.

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. In addition, cells showing morphological changes suggestive of apoptosis, such as nuclear condensation and fragmentation, did not show evidence of DNA fragmentation using the ApopTag in situ digoxigenin nucleotide labelled, peroxidase detection system. Further studies using annexin V flow cytometric analysis and pulsed field gel electrophoresis were also unable to detect evidence of apoptosis as a significant cause of cell death in megaloblastic anaemia.

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. PARTICIPANTS: 7 nursing sisters, 4 medical students, 2 lay persons. OUTCOME MEASURES: Haemoglobin estimates obtained with the colour scale were compared with the 'true Hb' values determined by the H x 3 Bayer-Technicon automated blood analyser. RESULTS: Although individuals varied in their abilities to use the colour scale, its performance was generally very good when measured against automated haemoglobinometry, as determined by bias and regression analysis and also in terms of its capacity to detect anaemia, as measured by sensitivity, specificity and positive and negative predictive values. CONCLUSIONS: Haemoglobin estimates obtained with the World Health Organisation colour scale are generally reliable, although cognisance should be taken of individual variability. While the utility of the device in monitoring response to therapy remains to be seen, it promises to be a suitable method for mass screening for anaemia.

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 (0.2 microM), PM and CHX nevertheless elicited the phenomenon of superinduction, possibly through mechanisms related to intracellular signalling.

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. The ability of the parasites to grow in red cells of the Dantu and Henshaw phenotypes was also assayed by 3[H] hypoxanthine incorporation. Relative to control red cells, S-s-U- cells and Dantu cells were less suitable as host cells for P. falciparum in vitro. In contrast, cells expressing the Henshaw antigen were equally sensitive to P. falciparum infection as were normal controls. These data support the notion that glycophorins play an important role in P. falciparum infection. Further studies are required to evaluate the epidemiological significance of these results.

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. The expression of the proto-oncogene c-myc has been strongly variously implicated in the regulation of the apoptotic cascade. Since we recently found that a low dose of the protein synthesis inhibitor PM activated the apoptotic cascade in HL-60 leukaemic cells, the current study was undertaken to examine c-myc mRNA transcript levels in such cells, and to assess the relationship, if any, between PM-elicited c-myc mRNA superinduction and subsequent activation of the apoptotic cascade. PM was employed in vitro at doses of 0.9 microM and 2 microM. Dose-dependent c-myc mRNA superinduction was present at 1 hour of PM-exposure, and was associated with subsequent activation of the apoptotic cascade at 24 hours of exposure. Apoptosis was confirmed morphologically as evidenced by chromatin condensation, nuclear fragmentation and the formation of apoptotic bodies, and by DNA agarose gel electrophoresis which showed the pattern of double-stranded DNA fragments that result from the activation of an endogenous endonuclease. [C14]Leucine incorporation studies at 1 hour demonstrated minimal protein synthesis inhibition at doses used, suggesting that c-myc mRNA superinduction in this context may have been the result of mechanisms which were independent of the inhibition of synthesis of new proteins, such as interruptions in signal transduction.

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. In unsynchronized cells, mafosfamide exposure was associated with an S-phase accumulation, a suggestion of a G2-phase arrest and morphological and biochemical evidence of apoptosis. In cells that had been synchronized by the double thymidine block method, S-phase progression was considerably delayed in the presence of mafosfamide. The apoptosis that was evident in mafosfamide-treated cells 12 hours after release from the thymidine block was found to occur in the presence of S-phase and G2-phase cell-cycle arrests. Taken together, the current data suggest that mafosfamide may have potential synergism with other anticancer agents that elicit similar cell-cycle arrests as well as with chemotherapeutic drugs that activate the apoptotic cascade.

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 0.1 to 20 micrograms/ml. No changes in c-myc mRNA levels were evident after 1 hour of exposure to Mafosfamide. After 6 and 24 hours of Mafosfamide-exposure, however, there was a dose- and time-dependent decrease in c-myc transcripts. c-myc mRNA expression was reduced to a greater extent than was either beta-actin of GAPDH expression. Morphological, biochemical and ultrastructural evidence of apoptosis accompanied the Mafosfamide-induced c-myc mRNA down-regulation at 24 hours. We conclude that, in the context of Mafosfamide-treated HL-60 cells, upregulation of c-myc mRNA transcription was not fundamental for the activation of the apoptotic cascade.