Search

Abstract Background Tick cell lines are now available from fifteen ixodid and argasid species of medical and veterinary importance. However, some tick cell lines can be difficult to cryopreserve, and improved protocols for short- and long-term low temperature storage will greatly enhance their use as tools in tick and tick-borne pathogen research. In the present study, different protocols were evaluated for cold storage and cryopreservation of tick cell lines derived from Rhipicephalus (Boophilus) decoloratus, Rhipicephalus (Boophilus) microplus, Ixodes ricinus and Ixodes scapularis. For short-term cold storage, cells were kept under refrigeration at 6°C for 15, 30 and 45 days. For cryopreservation in liquid nitrogen, use of a sucrose-phosphate-glutamate freezing buffer (SPG) as cryoprotectant was compared with dimethylsulfoxide (DMSO) supplemented with sucrose. Cell viability was determined by the trypan blue exclusion test and cell morphology was evaluated in Giemsa-stained cytocentrifuge smears. Results Cold storage at 6°C for up to 30 days was successful in preserving R. (B.) microplus, R. (B.) decoloratus, I. ricinus and I. scapularis cell lines; lines from the latter three species could be easily re-cultivated after 45 days under refrigeration. While cell lines from all four tick species cryopreserved with 6% DMSO were successfully resuscitated, the R. (B.) decoloratus cells did not survive freezing in SPG and of the other three species, only the R. (B.) microplus cells resumed growth during the observation period. Conclusions This constitutes the first report on successful short-term refrigeration of cells derived from R. (B.) decoloratus, R. (B.) microplus, and I. ricinus, and use of SPG as an alternative to DMSO for cryopreservation, thus making an important contribution to more reliable and convenient tick cell culture maintenance.

Chemokine production by cancer cells constitutes a duality. Leukocyte recruitment under the pressure of chemokines may be beneficial for the host or for the tumor. Recently, the chemokine fractalkine and its receptor CX3CR1 have been shown to be expressed in hepatocytes in vivo and in a human hepatocarcinoma cell line in vitro. Therefore, the aim of this study was to analyze the expression of CX3CR1 in hepatocellular carcinoma (HCC) in vivo and to investigate the prevalence of the genetic CX3CR1 polymorphism V249I in HCC patients since this polymorphism has been associated with reduced number of fractalkine binding sites, reduced cell-cell adhesion and decreased signaling and chemotaxis. Genotyping was performed in 183 patients with histologically proven HCC and 99 healthy controls by RFLP-analysis. The frequency of the individual genotypes was similar in HCC patients and controls. The V249I polymorphism revealed no association with tumor grade and stage, the presence of extrahepatic metastasis or the degree of fibrosis in non-tumorous tissue. In addition to genotyping, CX3CR1 mRNA expression was analyzed by quantitative PCR in 9 HCC specimens and in 6 cases in corresponding non-tumorous liver tissues. CX3CR1 mRNA expression levels in HCC showed high variation between individual patients. Similarly, expression in HCC compared to non-tumorous liver varied, from strong downregulation to remarkable upregulation. CX3CR1 mRNA expression levels showed no correlation to the V249I polymorphism. In summary, these results suggest that the patho-physiological role of individual chemokines in carcinogenesis may vary and that the functional CX3CR1 polymorphism V249I is no genetic risk factor for HCC. However, additional independent studies in HCC patients with different ethnic background will be needed to confirm the present study and to elucidate the functional role of CX3CR1 and its polymorphism V249I in chronic liver disease and hepatocarcinogenesis.

Delayed-type hypersensitivity (DTH) testing and total lymphocyte counts as measures of cell-mediated immune function were assessed for medical patients in Dar es Salaam, Tanzania. DTH testing was performed with the Multitest CMI device which simultaneously administers seven antigens. Of 201 patients completing DTH testing, 90 were HIV seropositive. Anergy occurred more frequently among HIV-seropositive patients (39 of 90) as compared with HIV-seronegative patients (17 of 111). DTH skin test reactivity, measured by anergy, the number of positive antigens, and the combined DTH response induration, was significantly related to the clinical stage of HIV disease. Median total lymphocyte counts were significantly lower in HIV-seropositive patients than in HIV-seronegative patients (1,130 vs. 1,680 lymphocytes x 10(6)/L). Total lymphocyte counts decreased with increasing severity of HIV disease. In multivariable analysis, the number of positive antigens in DTH testing and lymphopenia significantly predicted HIV infection. The findings suggest that DTH testing and total lymphocyte counts may be useful, inexpensive tests of immune function in African patients with HIV disease.

Objective: To evaluate the impact of the Duke University Medicine Residency International Health Program (IHP) on program participants and to evaluate the relationship of the IHP to the residency program., Subjects and Methods: The Duke University Medicine Residency Program classes of 1988 to 1996 participated in a questionnaire-based survey. All program participants (n = 59), a group of nonparticipants (n = 138), and residents who had not yet had an opportunity to participate (preparticipants; n = 106)., Results: The overall response rate to the questionnaire was 93%. Participation exceeded expectations and had a strongly positive impact on personal and professional lives of the majority of the participants. Participants reported a significant positive impact on their training in internal medicine and their knowledge of tropical medicine. A minority of nonparticipants identified a positive effect in these areas due to conferences and interactions with their participating colleagues. Participants who changes career plans during residency tended to move toward areas of general internal medicine or public health, in contrast to nonparticipants who tended to change areas of subspecialty or chose private practice. The IHP was identified as a significant factor for selection of the Duke Medicine Residency by 42% of the preparticipant group. Nearly all of the respondents (99%) indicated that the IHP should be continued., Conclusion: The IHP has a measurable positive impact on the participants, as well as on the Medicine Residency Program.

The clinical utility of the World Health Organization (WHO) clinical case definition (CCD) of acquired immune deficiency syndrome (AIDS) in Africa, several proposed modifications of the WHO CCD, and two proposed screening algorithms for human immunodeficiency virus (HIV) infection were examined in adult medical inpatients in Dar es Salaam, Tanzania. Sensitivity, specificity, and positive and negative predictive values were determined for the CCDs and screening algorithms. Multivariable analysis identified factors with high accuracy for HIV infection. Of 223 patients enrolled in the study, 95 were seropositive for HIV infection. The WHO CCD and the modified CCDs had low sensitivities (14.7-32.6%) but high specificities (95.3-99.2%) and positive predictive values (83.8-94.7%). The screening algorithms had moderate sensitivities (66.3-77.9%) and poor specificities (46.1-79.7%). Multivariable analysis consistently identified oral candidiasis and lymphadenopathy as the best predictors of HIV infection. Although patients with asymptomatic or early HIV infection may be missed by clinical criteria, in a high prevalence population, AIDS may be diagnosed accurately clinically because of the effect of prevalence on the positive predictive values of the CCDs. Furthermore, selection of patients for HIV serologic testing may be guided by simple combinations of clinical features.

Setting: Large academic medical center in Tanzania., Objectives: To determine the etiologies and outcomes of large pericardial effusions in HIV-infected and uninfected patients., Design: Prospective cohort study of patients admitted with new large pericardial effusions, confirmed echocardiographically. Patients had pericardial biopsies and drainage with extensive analysis of tissue and fluid specimens, and were followed with clinical and echocardiographic examinations., Results: Of 28 patients with large pericardial effusions, 19 were infected with HIV-1. 22 had invasive diagnostic procedures: 14 of 14 HIV-infected patients, but only 4 of 8 non-HIV-infected patients, had tuberculous pericarditis (P = 0.01). All but 1 of the HIV-infected patients had strongly positive tuberculin skin tests, and short-term outcomes were similar in the 2 groups., Conclusion: TB is the predominant cause of large pericardial effusion in HIV-infected patients in this setting; non-HIV-infected patients are more likely to have other etiologies. These patients were at an early stage of HIV infection and responded well to treatment. In settings where microbiological studies are not routinely available, HIV-infected patients with large pericardial effusions may be treated empirically for tuberculosis and monitored for improvement. If improvement does not follow within 2-4 weeks further studies are indicated. HIV-negative patients should undergo diagnostic evaluation initially.

Plasmodium falciparum-infected erythrocytes (PfE) were collected from acutely infected children in The Gambia and Tanzania and cultured for more than 30 hr until the parasites were mature trophozoites. Sera collected from these countries, other African countries, Asia, and South America were used in the PfE microagglutination test to determine whether PfE from East and West Africa share surface antigens. From the patterns of agglutination reactivity, we identified extensive antigenic diversity in surface antigens, but obtained no evidence for greater differences between isolates from East or West Africa and those within one region. The majority of sera from immune adults from The Gambia, Tanzania, Sudan, Nigeria, or Ghana were pan-agglutinating, and agglutinated all PfE isolates from The Gambia and Tanzania. Some sera from immune adults of Irian Jaya also agglutinated each of the seven African isolates, while others agglutinated many but not all of the isolates, similar to sera from immune adults of Flores, Indonesia. In contrast, sera from nonimmune adults from Colombia agglutinated few of the African isolates. It was remarkable, however, that sera from nonimmune Colombians agglutinated any African isolates. Our results are consistent with the following conclusions: some PfE surface antigen(s) are very diverse; this diversity is a feature of the parasite worldwide; the repertoire of isolate-specific surface antigens, although large, includes antigens that are either identical or antigenically cross-reactive in geographically very distant parasite populations; and African adults have pan-agglutinating antibodies that may contribute to protective immunity. Such pan-agglutinating antibodies could reflect the accumulation of a large repertoire of isolate-specific antibodies. The contribution of antibody against any shared PfE surface antigen to the pan-agglutinating reactivities is unknown and awaits development of the appropriate reagents.

Concurrent infection with HIV-1 and Mycobacterium tuberculosis is increasingly common in East Africa. In the past, a drug regimen consisting of 2 months of intramuscular streptomycin plus 12 months of isoniazid and thiacetazone has been used in tuberculosis control programs with acceptable efficacy and low incidence of adverse reactions. Anecdotal reports of increasing cases of Stevens-Johnson syndrome prompted a 2 month prospective search for cases of severe cutaneous hypersensitivity reactions at Muhimbili Medical Centre in Dar es Salaam, Tanzania. Five such patients were admitted to a single ward during this time, 4 of whom were HIV-seropositive and all of whom were being treated with isoniazid and thiacetazone. These findings have implications for the management of tuberculosis in East Africa and perhaps other countries with high prevalence of both HIV-1 and tuberculosis.

The number of patients admitted to Muhimbili Medical Centre, Tanzania, with pericardial effusions rose after the epidemic of acquired immunodeficiency syndrome (AIDS) began. To investigate a possible relation all patients with suspected pericardial disease admitted between Oct 1, 1987, and March 31, 1989, were studied. 28 of 42 patients (67%) were seropositive for human immunodeficiency virus (HIV). 28 of 39 patients (72%) with pericardial effusion were HIV-seropositive compared with 0 of 3 without effusion. More HIV-seronegative than HIV-seropositive patients were receiving antituberculous chemotherapy and had ascites at enrollment. Only 5 of 28 HIV-seropositive patients had clinical signs of AIDS. 9 of 14 HIV-seropositive patients tested had positive Mantoux tests. There were no significant differences between the HIV-seropositive and seronegative groups in the duration of symptoms, laboratory results, X-ray or ultrasound findings, frequency of tamponade, or mortality. 38 patients were treated for tuberculosis. Pericardial effusion is strongly associated with, and an early manifestation of, HIV infection in Tanzania.