Identification and Characterization of a Secondary Sodium-Binding Site and the Main Selectivity Determinants in the Human Concentrative Nucleoside Transporter 3.

The family of concentrative Na+/nucleoside cotransporters in humans is constituted by three subtypes, namely, hCNT1, hCNT2, and hCNT3. Besides their different nucleoside selectivity, hCNT1 and hCNT2 have a Na+/nucleoside stoichiometry of 1:1, while for hCNT3 it is 2:1. This distinct stoichiometry of subtype 3 might hint the existence of a secondary sodium-binding site that is not present in the other two subtypes, but to date their three-dimensional structures remain unknown and the residues implicated in Na+ binding are unclear. In this work, we have identified and characterized the Na+ binding sites of hCNT3 by combining molecular modeling and mutagenesis studies. A model of the transporter was obtained by homology modeling, and key residues of two sodium-binding sites were identified and verified with a mutagenesis strategy. The structural model explains the altered sodium-binding properties of the hCNT3C602R polymorphic variant and supports previously generated data identifying the determinant residues of nucleoside selectivity, paving the way to understand how drugs can target this plasma membrane transporter.

Cell mediated and antibody immune response to inactivated hepatitis A vaccine.

The humoral and cellular immune response to inactivated hepatitis A vaccine was investigated dynamically in a time elapse study over 1 year. Fourty-five healthy volunteers, seronegative for anti-HAV, were vaccinated with 1440 enzyme-linked immunosorbent assay units (EU) of formalin-inactivated hepatitis A virus following a 0--6-month schedule. Serum anti-HAV levels and HAV-specific proliferation of peripheral blood mononuclear cells were measured at several time points over a 26- and 28-week period after the first and second injection, respectively. Distinct B and T cell responses were determined within 14 days after primary vaccination. The booster vaccination-induced immediate peak levels for the humoral (anti-HAV GMC=5376mIU/ml) as well as the cellular (median Deltacpm=14173cpm) response.

Pertussis-specific cell-mediated immunity in infants after vaccination with a tricomponent acellular pertussis vaccine.

The aim of this study was to investigate pertussis-specific cell-mediated immunity in infants vaccinated with a tricomponent acellular vaccine. Infants were investigated during a primary vaccination schedule from the third month of life to the sixth month as well as before and after a booster at 15 to 24 months. This is the first report of specific cell-mediated immune responses to pertussis-related antigens in infants below the age of 12 months. Our data show that the vaccine induces T-cell responses specific for the vaccine components, detoxified pertussis toxin, filamentous hemagglutinin, and pertactin, that increase progressively over the course of the vaccination schedule. In contrast to declining antibody titers, cell-mediated immune responses are stable over the postprimary to prebooster period. Vaccination results in a progressive increase in the number of T cells that express activation marker CD45RO preferentially on CD4-positive T cells after stimulation with pertussis antigens. Measurements of cytokine secretion profiles demonstrated a preferential induction of interleukin 2- and gamma interferon-producing T-helper 1 cells and only low production of interleukin 10. The observed persistence of the specific cell-mediated immunity may have a bearing on the protective mechanisms induced by pertussis vaccination. Cell-mediated immunity requires further study, particularly to improve our understanding of the persistence of protection afforded by vaccination up to the administration of booster doses.

[Lymphadenitis colli due to non-tuberculous mycobacteria (NTM): a case-series and review of the literature]. / Lymphadenitis colli durch nichttuberkulöse Mykobakterien (NTM) im Kindesalter -- Eine Fallserie und Literaturübersicht.

OBJECTIVE: Lymphadenitis colli due to NTM should always be considered in children with cervical Lymphadenitis. For Germany there is a lack of data concerning the incidence, the epidemiology, the diversity and frequency of the different bacteria, the diagnosis, the clinical manifestation and the medical treatment. METHODS: By means of a questionnaire, which was retrospective for 1985 to 1994 and was sent to 277 children's hospitals in Germany, we collected data on Lymphadenitis colli in Germany. In our study we also incorporated cases from the "National Laboratory for Mycobacteria" in Borstel as well as six cases from our hospital in Mainz. Therefore our data includes both clinical (28) and laboratory (30) cases. Additionally we screened the literature on "Lymphadenitis colli in children due to NTM". RESULTS: A total of 51 cases of Lymphadenitis due to NTM could be identified. The illness occurs typically in young children up to six years of age. The most frequent cause were species of the Mycobacterium avium-intracellulare-scrofulaceum complex. Except for the local diagnosis of a cervical Lymphadenitis other clinical symptoms are missing, just as specific laboratory parameters with a subacute or chronic course. The tuberculin skin test can be false positive. The diagnosis is confirmed by biopsy and histology as well as through microbiological tests. CONCLUSIONS: The best treatment is complete surgical excision, whereas the importance of additional or exclusive treatment with Clarithromycin, Rifabutin and other antibiotics could not be clarified completely. But in patients with AIDS Rifabutin and other drugs could perhaps be useful, even for prophylaxis. Also if complete excision is impossible, treatment with certain drugs (Clarithromycin or Azithromycin in combination with Rifampicin) will be recommended. It still remains in question if NTM infections in children are really increasing.

Immunogenicity and reactogenicity of HbOC vaccine administered simultaneously with acellular pertussis vaccine (DTaP) into either arms or thighs of infants.

To evaluate the reactogenicity and immunogenicity of a Haemophilus influenzae type b conjugate vaccine (HbOC) and of a tricomponent acellular pertussis vaccine (DTaP) when injected simultaneously into either contralateral arms or into contralateral thighs, 110 infants were enrolled to receive three doses of DTaP at 3, 4, and 5 months and two HbOC doses at 3 and 5 months of age. Administration of either of the two vaccines into arms was associated with significantly more local side effects than administration into thighs. There was no difference in geometric mean concentration (GMC) values for any of the four vaccine antigens between subjects who had been vaccinated into arms or thighs. After immunization, all children had protective antibody titers to diphtheria toxin. While post vaccination the mean anti-tetanus toxoid GMC was > or = 1.25 IU/ml, there was no significant rise as compared to the GMC before vaccination. GMCs of antibodies against the various pertussis antigens were similar to those observed before with the same DTaP vaccine. The simultaneous administration of DTaP and HbOC was safe and immunogenic irrespective of the site of vaccine administration, but significantly more local reactions occurred when vaccines were injected into arms.