HIV testing for the non-specialist.
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Early Diagnosis↗
Biomedical subjects
K Kemp
Publications and source records attributed to K Kemp.
Cytokine production and apoptosis among T cells from patients under treatment for Plasmodium falciparum malaria.
Available evidence suggests that Plasmodium falciparum malaria causes activation and reallocation of T cells, and that these in vivo primed cells re-emerge into the periphery following drug therapy. Here we have examined the cytokine production capacity and susceptibility to programmed cell death of peripheral T cells during and after the period of antimalarial treatment. A high proportion of peripheral CD3+ cells had an activated phenotype at and shortly after time of admission (day 0) and initiation of therapy. This activation peaked around day 2, and at this time-point peripheral T cells from the patients could be induced to produce cytokines at conditions of limited cytokine response in cells from healthy control donors. Activated CD8hi and TCR-gammadelta+ cells were the primary IFN-gamma producers, whereas CD4+ cells constituted an important source of TNF-alpha. The proportion of apoptotic T cells was elevated at admission and peaked 2 days later, while susceptibility to activation-induced cell death in vitro remained increased for at least 1 week after admission. Taken together, the data are consistent with the concept of malaria-induced reallocation of activated T cells to sites of inflammation, followed by their release back into the peripheral blood where they undergo apoptotic death to re-establish immunological homeostasis as inflammation subsides. However, the high proportion of pre-apoptotic cells from the time of admission suggests that apoptosis also contributes to the low frequency and number of T cells in the peripheral circulation during active disease.
Animals↗
Is ageing associated with a shift in the balance between Type 1 and Type 2 cytokines in humans?
The balance between Type 1 and Type 2 cytokines is important for the outcome of several infectious diseases. As elderly humans show increased morbidity and mortality from infectious diseases, this study tests if ageing is associated with a change towards Type 2 dominance in T cells. Expression of IFN-gamma, and IL-4 was measured in CD4+ and CD8+ T cells by flow cytometry in three groups: young controls (n=28), 81-year-olds (n=22), and centenarians (n=25). The major findings were that the percentage of IFN-gamma+ as well as IL-4+ T cells was increased in aged subjects. Furthermore, after adjusting for decreased lymphocyte counts in the elderly, the concentration in the blood of IFN-gamma+ and IL-4+ CD8+ T cells was still increased in the 81-year-olds. In centenarians, a shift towards a relative dominance of Type 2 cytokine expression was found within CD8+ T cells. Furthermore, the percentage of T cells with cytokine expression was closely correlated to the in vivo expression of CD95 and CD45RO. In conclusion, we found some evidence for an age-related shift towards a Type 2 cytokine profile.
Adult↗
Cloning, expression and antigenicity of the L. donovani reductase.
The protozoan parasite Leishmania undergoes a morphological and biochemical transformation from the promastigote to the amastigote form during its life cycle, which is reflected in the expression of stage-specific proteins. One of these proteins shows homology to a superfamily of reductase proteins. We have cloned the reductase gene from L donovani and have shown that it differs in only one nucleotide from the L. major homologue, resulting in one amino acid change. A cytosine (C) to guanine (G) transposition in the coding sequence leads to a nonconserved substitution of asparagine (N) for lysine (K). Only 2 of 22 plasma samples from patients with visceral leishmaniasis were found to have detectable anti-reductase antibodies and peripheral blood mononuclear cells (PBMC) from one of three individuals previously infected with visceral leishmaniasis proliferated in the presence of recombinant reductase protein. Interestingly, 6 of 10 PBMC isolated from Danish controls proliferated in the presence of the reductase protein. Intracellular IFNgamma was found in a significant percentage of cells in all the tested PBMC cultures from Danes, whereas IL4 was only found in a small proportion of cells, or not at all. The results indicate the presence of cross-reacting CD45R0 memory T-cells in individuals not exposed to Leishmania. Several previous studies have shown that T-cells from nonexposed individuals often respond to crude Leishmania antigen preparations. The present study suggests that this reactivity is partly caused by T-cells recognising L. donovani reductase.
Amino Acid Sequence↗
The erosive effects of some mouthrinses on enamel. A study in situ.
BACKGROUND: There are both anecdotal clinical and laboratory experimental data suggesting that low pH mouthrinses cause dental erosion. This evidence is particularly relevant to acidified sodium chlorite (ASC) formulations since they have plaque inhibitory properties comparable to chlorhexidine but without the well known local side effects. AIM: Studies in situ and in vitro were planned to measure enamel erosion by low pH mouthrinses. The study in situ measured enamel erosion by ASC, essential oil and hexetidine mouthrinses over 15-day study periods. The study was a 5 treatment, single blind cross over design involving 15 healthy subjects using orange juice, as a drink, and water, as a rinse, as positive and negative controls respectively. 2 enamel specimens from unerupted human third molar teeth were placed in the palatal area of upper removable acrylic appliances which were worn from 9 a.m. to 5 p.m., Monday to Friday for 3 weeks. Rinses were used 2x daily and 250 ml volumes of orange juice were imbibed 4x daily. Enamel loss was determined by profilometry on days 5, 10 and 15. The study in vitro involved immersing specimens in the 4 test solutions together with a reduced acid ASC formulation for a period of 4 h under constant stirring; Enamel loss was measured by profilometry every hour. RESULTS: Enamel loss was in situ progressive over time with the 3 rinses and orange juice but negligible with water. ASC produced similar erosion to orange juice and significantly more than the two proprietary rinses and water. The essential oil and hexetidine rinses produced similar erosion and significantly more than water. Enamel loss in vitro was progressive over time, and the order from low to high erosion was reduced acid ASC, ASC, Essential oil, and hexetidine mouthrinses and orange juice. CONCLUSION: Based on the study in situ, it is recommended that low pH mouthrinses should not be considered for long term or continuous use and never as pre-brushing rinses. In view of the plaque inhibitory efficacy of ASC, short- to medium-term applications similar to those of chlorhexidine would be envisaged.
Adult↗
High-dose stabilized chlorite matrix WF10 prolongs cardiac xenograft survival in the hamster-to-rat model without inducing ultrastructural or biochemical signs of cardiotoxicity.
WF10 is a stabilized chlorite matrix with immunosuppressive effects. In vitro studies have demonstrated its ability to suppress T cells and delay or abolish antigen presentation. Hence, WF10 may prove useful to prolong graft survival after transplantation. In this study, we evaluated the use of high dose WF10 as a single drug regimen in the hamster-to-rat xenotransplantation model and searched for possible cardiotoxic side effects. WF10 prolonged cardiac xenograft survival, but did not induce tolerence or inhibit pathological signs of acute rejection. Hamsters from the donor population, receiving high dose WF10 for 5 days, were compared with a matched control group. Ultrastructural examination of cardiac tissue as well as biochemical analysis of the cardiac enzymes troponin I, myoglobin and MB isoenzyme of creatine kinase showed no signs of damage. Thus, while prolonging graft survival, high dose WF10 seems to be non-cardiotoxic and as such should not contribute to the differential diagnosis of acute graft failure.
Animals↗
West African donors have high percentages of activated cytokine producing T cells that are prone to apoptosis.
Persistent immune activation has been suggested to affect the subset composition and activation status of peripheral blood cells. In this study we have compared peripheral blood mononuclear cells (PBMC) from a group of Ghanaians living in an area with high prevalence of malaria, mycobacteria, EBV and helmintic infections to a group of European counterparts. Our hypothesis was that persistent challenge with microorganisms is associated with increased production of cytokines and increased susceptibility of periphery cells to undergo apoptosis. We observed an increased frequency of activated T cells and a higher frequency of IL-4- but not IFN-gamma-producing cells in the periphery of the Ghanaians. The IL-4 was produced mainly by CD4+ cells, in contrast to IFN-gamma which was produced equally by CD4+, CD8+ and TCR-gammadelta+ cells. The frequencies of cytokine-producing cells were highly correlated to the frequencies of activated cells. Finally, cells from Ghanaians were more susceptible to activation-induced apoptosis. These results may explain why some epidemic diseases seem to have a different mode of transmission in Africa compared to the western world, and may thus be of importance when vaccine strategies are considered in Africa.
Apoptosis↗
Identification of IFN-gamma-producing CD4+ T cells following PMA stimulation.
Treatment of T cells with phorbol esters, such as phorbol myristate acetate (PMA), induces downregulation of CD4, making unambiguous identification of this subset difficult. In this study, the kinetics of intracellular expression of interferon-gamma (IFN-gamma) and downmodulation of surface CD4 were measured in peripheral blood mononuclear cells (PBMC) after PMA stimulation. The number of IFN-gamma-producing cells increased within a 4-h period while the fluorescence intensity of the CD4(+) cell population decreased, and the two phenomena were correlated (n = 9; p = 0.01). Our data suggest that intracellular staining of CD4 together with cytokine staining will make identification of CD4(+) cells possible and facilitate the procedure of intracellular staining of cytokines.
Adult↗
Lumbosacral plexopathy in gunshot wounds and motor vehicle accidents: comparison of electrophysiologic findings.
OBJECTIVE: To characterize the differences between injuries to the lumbosacral (LS) plexus caused by gunshot wounds (GSW) and motor vehicle crashes (MVC) with regard to the location and extent of involvement. DESIGN: A retrospective review of electrophysiologic data from an electromyography laboratory of a county hospital. Nineteen patients with GSW and ten patients with MVC diagnosed by electromyography with an LS plexopathy were included in the study. Injuries were categorized by the number of anatomic quadrants of the LS plexus: upper anterior, upper posterior, lower anterior, and lower posterior. Comparison of upper vs. lower portions and bilaterality of LS plexus involvement was also made. Statistical analyses were performed with two-tailed Fisher's exact and general association tests. RESULTS: Lower portions of the plexus were involved more frequently in patients with MVC compared those observed in patients with GSW. Upper portions of the LS plexus were more involved compared with the lower portions in patients with GSW injuries. More sections of the plexus were involved in patients with MVC compared with those in patients with GSW. CONCLUSIONS: Compared with patients with MVC, patients with GSW had a greater chance of involvement of the upper portion of the plexus. The reverse was true for the lower portion. Hopefully this information will aid the electromyographer and rehabilitation team in the diagnosis and treatment of traumatic plexopathies caused by different etiologies.
Accidents, Traffic↗
Perturbation and proinflammatory type activation of V delta 1(+) gamma delta T cells in African children with Plasmodium falciparum malaria.
gamma delta T cells have variously been implicated in the protection against, and the pathogenesis of, malaria, but few studies have examined the gamma delta T-cell response to malaria in African children, who suffer the large majority of malaria-associated morbidity and mortality. This is unfortunate, since available data suggest that simple extrapolation of conclusions drawn from studies of nonimmune adults ex vivo and in vitro is not always possible. Here we show that both the frequencies and the absolute numbers of gamma delta T cells are transiently increased following treatment of Plasmodium falciparum malaria in Ghanaian children and they can constitute 30 to 50% of all T cells shortly after initiation of antimalarial chemotherapy. The bulk of the gamma delta T cells involved in this perturbation expressed V delta 1 and had a highly activated phenotype. Analysis of the T-cell receptors (TCR) of the V delta 1(+) cell population at the peak of their increase showed that all expressed V gamma chains were used, and CDR3 length polymorphism indicated that the expanded V delta 1 population was highly polyclonal. A very high proportion of the V delta 1(+) T cells produced gamma interferon, while fewer V delta 1(+) cells than the average proportion of all CD3(+) cells produced tumor necrosis factor alpha. No interleukin 10 production was detected among TCR-gamma delta(+) cells in general or V delta 1(+) cells in particular. Taken together, our data point to an immunoregulatory role of the expanded V delta 1(+) T-cell population in this group of semi-immune P. falciparum malaria patients.
CD3 Complex↗
Comparative genomic sequence analysis of the human and mouse cystic fibrosis transmembrane conductance regulator genes.
The identification of the cystic fibrosis transmembrane conductance regulator gene (CFTR) in 1989 represents a landmark accomplishment in human genetics. Since that time, there have been numerous advances in elucidating the function of the encoded protein and the physiological basis of cystic fibrosis. However, numerous areas of cystic fibrosis biology require additional investigation, some of which would be facilitated by information about the long-range sequence context of the CFTR gene. For example, the latter might provide clues about the sequence elements responsible for the temporal and spatial regulation of CFTR expression. We thus sought to establish the sequence of the chromosomal segments encompassing the human CFTR and mouse Cftr genes, with the hope of identifying conserved regions of biologic interest by sequence comparison. Bacterial clone-based physical maps of the relevant human and mouse genomic regions were constructed, and minimally overlapping sets of clones were selected and sequenced, eventually yielding approximately 1.6 Mb and approximately 358 kb of contiguous human and mouse sequence, respectively. These efforts have produced the complete sequence of the approximately 189-kb and approximately 152-kb segments containing the human CFTR and mouse Cftr genes, respectively, as well as significant amounts of flanking DNA. Analyses of the resulting data provide insights about the organization of the CFTR/Cftr genes and potential sequence elements regulating their expression. Furthermore, the generated sequence reveals the precise architecture of genes residing near CFTR/Cftr, including one known gene (WNT2/Wnt2) and two previously unknown genes that immediately flank CFTR/Cftr.
Animals↗
WF10 in xenotransplantation-a potential new approach.
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Animals↗
What is the cause of lymphopenia in malaria?
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Animals↗
Comparison of the immune profile of nonhealing cutaneous Leishmaniasis patients with those with active lesions and those who have recovered from infection.
Th1-type cellular immune responses play a critical role in protection against infection with Leishmania parasites, whereas activation of Th2-type cells results in progressive disease. Cutaneous leishmaniasis caused by Leishmania major is often a self-healing disease; however, persistent nonhealing forms are also known. In the present study, we have described cell-mediated immune responses in nonhealing patients by measuring T-cell proliferation, cytokine production, and phenotypic characterization of these cells. The responses were compared with those of patients with active lesions, patients who had recovered from infection, and healthy controls. Peripheral blood mononuclear cells from patients with active lesions and recovered donors proliferated vigorously and produced Th1-type cytokine when stimulated with L. major antigens, whereas in nonhealing patients the proliferative responses were significantly lower and showed a Th2-type response to Leishmania antigens. Interleukin-10 (IL-10) production was not a feature of L. major stimulation. Flow cytometric analysis revealed that L. major antigen induced proliferation of the CD4-positive population and that these cells were the major source of gamma interferon and IL-4. These results show a distinct dichotomy in the cytokine response to L. major infection.
Adolescent↗
Bismuth autometallography: protocol, specificity, and differentiation.
We provide a detailed protocol of the autometallographic bismuth technique and evaluate the specificity of the technique. We show by the multi-element technique "proton-induced X-ray microanalysis" (PIXE) that the autometallographic grains contain silver, bismuth, and sulfur, proving that autometallography can be used for specific tracing of bismuth bound as bismuth sulfide clusters in tissue sections from Bi-exposed animals or humans. In sections from animals exposed concurrently to selenium and bismuth, the autometallographic grains also contain selenium. This demonstrates that, if present in excess in the organisms, selenium will bind to exogenous bismuth, creating bismuth selenide clusters. As a further possible control for specificity and as a tool for differentiating among autometallographically detectable metals in sections containing more than one, we describe how bismuth sulfide clusters can be removed from Epon-embedded tissue sections by potassium cyanide.
Animals↗
Cytokine-producing T cell subsets in human leishmaniasis.
Leishmania specific Th1/Th2 cells have been identified in humans as well as in mice. There is a correlation between the clinical outcome of the infection and the cytokine response profile. Generally, the production of Th2 cytokines leads to severe infection, whereas the production of Th1 cytokines leads to subclinical or mild infections. In mice, an infection leads to a polarisation of either Th1 or Th2 Leishmania antigen specific cells. In contrast, both Th1 and Th2 Leishmania antigen specific cells can be identified in humans cured from L. donovani infections. Theoretically, Th1 cells and Th2 cells mutually down-regulate each other. However, the presence of antigen specific regulatory T cell subsets may provide an environment that allows the presence of both Th1 and Th2 cells.
Animals↗
Immunopathology of post kala-azar dermal leishmaniasis (PKDL): T-cell phenotypes and cytokine profile.
In Sudan, post kala-azar dermal leishmaniasis (PKDL) caused by Leishmania donovani develops in half of the patients treated for visceral leishmaniasis (kala-azar). In most patients lesions heal spontaneously, but in others symptoms are severe and persist for years. This study examined the immunological response in lesions of PKDL patients by immunohistochemistry and compared the findings with results obtained using peripheral blood mononuclear cells (PBMCs). In all lesions, parasites or parasite antigen were present and provoked the formation of an inflammatory infiltrate consisting of a mixture of macrophages, lymphocytes, and plasma cells. In patients who had high interferon-gamma (IFNgamma) responses to Leishmania antigen in vitro, compact epithelioid granulomas were formed. The inflammatory cells were mainly CD3(+) and interleukin-10 (IL10) was the most prominent cytokine in the lesions. However, IFNgamma was found in all and IL4 in most lesions, in varying amounts. PBMCs from all patients responded to Leishmania antigen by IFNgamma production or proliferation. The results indicate that PKDL develops as a result of an influx of immunocompetent cells into skin, which harbours parasites. The inflammatory response to the parasites is complex. It involves several cell types and cytokines, of which some are antagonistic. It is conceivable that the balance between these cytokines determines the outcome of the disease.
Adolescent↗
T-cell response in human leishmaniasis.
In the present communication we provide evidence for the existence of a Th1/Th2 dichotomy in the T-cell response to Leishmania antigens in human leishmaniasis. Our data suggest that the pattern of IL-4 and IFN-gamma response is polarised in these patients. Lymphocytes from individuals recovered from cutaneous leishmaniasis (CL) responded by IFN-gamma production following stimulation with Leishmania antigens whereas cells from patients recovered from visceral leishmaniasis (VL) showed a mixed pattern of IFN-gamma and IL-4 responses. The cells producing these cytokines were predominantly CD4+. Furthermore, IL-10 plays an important role in the development of post kala azar dermal leishmaniasis (PKDL) from VL. The balance between the parasitic-specific T-cell response plays an important regulatory role in determining the outcome of Leishmania infections in humans.
Antigens, Protozoan↗