Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.     

Evolutionary dynamics of the human immunoglobulin kappa locus and the germline repertoire of the Vkappa genes

We have determined the entire nucleotide sequence of the human immunoglobulin kappa locus, comprising a total of 1,010,706 nucleotides. The 76 Vkappa genes found by a hybridization-based approach and their classification in 7 families were confirmed. A Vkappa orphon located near the locus was also sequenced. In addition, we identified 55 novel Vkappa relics and truncated pseudogenes, which establish 5 new families. Among these 132 Vkappa genes, 46 have open reading frames. According to the databases and the literature, 32 unique Vkappa genes and 5 identical gene pairs form VJ-joints, 27 unique genes and 4 gene pairs are transcribed, and 25 unique genes and 4 gene pairs produce functional proteins. The Vkappa gene locus contains a 360-kb inverted duplication, which harbors 118 Vkappa genes. A comparison of the duplicated Vkappa genes suggests positive selection on the complementarity-determining regions of the duplicated genes by point mutations. The entire duplication unit was divided into 13 blocks, each of which has its distinct nucleotide sequence identity to its duplication counterpart (98.1 - 99.9 %). An inversion-mediated mechanism is suggested to generate the high-homology blocks. Based on the homology blocks and the mutation rates, the inverted duplication is assumed to have taken place approximately 5 million years ago. An orphon Vkappa gene near the kappa locus and a cluster of five Vkappa orphons on chromosome 22 have no counterparts within the kappa locus. This suggests possible mechanisms of the transposition of orphon Vkappa genes.     

Functional supertype of HLA-A2 in the presentation of Flu matrix p58-66 to induce CD8+ T-cell response in a Northern Chinese population

The functional supertype of HLA-A2 was investigated in the presentation of the A*0201-restricted Flu matrix p58-66 peptide to activate recall CD8+ T-cell response. In healthy Northern Chinese, the HLA-A2 supertype was mainly composed of the six alleles, A*0201 (26.4%), A*0206 (12.7%), A*0203 (8.2%), A*0207 (7.3%), A*0210 (1.8%) and A*0205 (0.9%), as analyzed by PCR using sequence specific primer (PCR-SSP) and sequence based typing (SBT). The IFN-gamma release Elispot assay was employed to assess effector CD8+ T cells. In A*0201-bearing individuals, the CD8+ T-cell response was potent when stimulated with autologous CD8- PBMCs. The frequency of the effector CD8+ T cells was 96.6% with the magnitude of effector CD8+ T cells of 225 SFC/5 x 104 CD8+ T cells and the RI of 25.7. In non-A*0201 individuals, the effector CD8+ T cells were minimally detectable while the peptide was presented by the autologous CD8- PBMCs. However, the induction of the response of CD8+ T cells obtained from non-A*0201 individuals was remarkably improved when the peptide was presented by autologous dendritic cells instead of CD8- PBMCs. The HLA-A2 alleles possessing cross-reactivity in the peptide presentation were mainly of A*0206 and non-A*0201 heterozygotes of A*0206 and A*0210. Moreover, A*0206 as the HLA-A2 functional supertype was further confirmed by tetramer assay. In two A*0206+ donors with CD8+ T-cell response to the peptide, the CD8+ T-cell frequency assessed by specific binding of peptide HLA-A*0201 tetramer was 4.62% and 1.66%, respectively. Thus, our results have substantiated the immunological relevance of the HLA-A2 supertype, which may benefit the design of peptide vaccines with the potential to be applicable in broader populations.     

Clearance of Chlamydia pneumoniae infection in H-2 class I human leucocyte antigen-A2.1 monochain transgenic mice

CD8+ T cells have been suggested to play an important role in protective immunity against pulmonary Chlamydia pneumoniae infection in mice. Moreover, several classical major histocompatibility complex class I - restricted cytotoxic CD8+ T lymphocytes (CTL) specific for C. pneumoniae- derived peptides have been identified. Here, we studied the outcome of C. pneumoniae infection in human leucocyte antigen (HLA)-A2.1 transgenic mice (HHD mice) that are only able to express a classical human class I molecule (HLA-A2.1). C. pneumoniae infection was self-restricted in HHD mice which were able to develop specific immune responses and a protective immunity against a subsequent rechallenge in a manner comparable to wildtype mice. Furthermore, accumulation of functional and C. pneumoniae-specific T cells to the site of infection was detected after challenge. Antigen processing and HLA-A2.1-dependent presentation was studied by immunizing the HHD mice with chlamydial outer protein N (CopN). Isolation of a peptide-specific CTL line from the CopN-immunized mice suggests that the HLA-A2.1 molecule can support the development of CTL response against a chlamydial protein in mice. These findings suggest that the transgenic mouse model can be used for further characterization of the HLA-A2.1-restricted CD8+ T-cell response during C. pneumoniae infection and for identification of CD8 epitopes from chlamydial antigens.     

Awareness of breast cancer incidence and risk factors among healthy women.

The efficacy of early breast cancer detection programmes seems to be mainly influenced by the awareness of breast cancer in general among healthy women. This study aimed to provide information about women's understanding of breast cancer incidence and risk of disease. Based on a newly developed questionnaire 2108 healthy women were asked about their knowledge and perceptions in relation to breast cancer incidence, risk factors, risk perception and level of concern. Of these women 78.8% were well aware of breast cancer in general terms. However, there were major aspects such as incidence or risk factors that were poorly understood. Only one-third correctly estimated the incidence of breast cancer; 95% understood breast cancer in the familial history as a risk factor, but only 57% understood the age risk; 37.1% of women perceived hormonal contraceptives and 35.9% hormonal replacement therapy as risk factors of breast cancer. The latter estimation was significantly higher in women above 40 years. Recommendations for the improvement of cancer prevention programmes include targeting understanding of lifetime risk of breast cancer, age as a risk factor, survival from breast cancer or hormonal factors. There is a need to separately address the perceptions of women depending on age, social status and educational levels.     

Analysis of exome sequence in 604 trios for recessive genotypes in schizophrenia

Genetic associations involving both rare and common alleles have been reported for schizophrenia but there have been no systematic scans for rare recessive genotypes using fully phased trio data. Here, we use exome sequencing in 604 schizophrenia proband–parent trios to investigate the role of recessive (homozygous or compound heterozygous) nonsynonymous genotypes in the disorder. The burden of recessive genotypes was not significantly increased in probands at either a genome-wide level or in any individual gene after adjustment for multiple testing. At a system level, probands had an excess of nonsynonymous compound heterozygous genotypes (minor allele frequency, MAF ⩽1%) in voltage-gated sodium channels (VGSCs; eight in probands and none in parents, P=1.5 × 10⁻⁴). Previous findings of multiple de novo loss-of-function mutations in this gene family, particularly SCN2A, in autism and intellectual disability provide biological and genetic plausibility for this finding. Pointing further to the involvement of VGSCs in schizophrenia, we found that these genes were enriched for nonsynonymous mutations (MAF ⩽0.1%) in cases genotyped using an exome array, (5585 schizophrenia cases and 8103 controls), and that in the trios data, synaptic proteins interacting with VGSCs were also enriched for both compound heterozygosity (P=0.018) and de novo mutations (P=0.04). However, we were unable to replicate the specific association with compound heterozygosity at VGSCs in an independent sample of Taiwanese schizophrenia trios (N=614). We conclude that recessive genotypes do not appear to make a substantial contribution to schizophrenia at a genome-wide level. Although multiple lines of evidence, including several from this study, suggest that rare mutations in VGSCs contribute to the disorder, in the absence of replication of the original findings regarding compound heterozygosity, this conclusion requires evaluation in a larger sample of trios.     

Cerebellar ataxia and Purkinje cell dysfunction caused by Ca2+-activated K+ channel deficiency

Malfunctions of potassium channels are increasingly implicated as causes of neurological disorders. However, the functional roles of the large-conductance voltage- and Ca(2+)-activated K(+) channel (BK channel), a unique calcium, and voltage-activated potassium channel type have remained elusive. Here we report that mice lacking BK channels (BK(-/-)) show cerebellar dysfunction in the form of abnormal conditioned eye-blink reflex, abnormal locomotion and pronounced deficiency in motor coordination, which are likely consequences of cerebellar learning deficiency. At the cellular level, the BK(-/-) mice showed a dramatic reduction in spontaneous activity of the BK(-/-) cerebellar Purkinje neurons, which generate the sole output of the cerebellar cortex and, in addition, enhanced short-term depression at the only output synapses of the cerebellar cortex, in the deep cerebellar nuclei. The impairing cellular effects caused by the lack of postsynaptic BK channels were found to be due to depolarization-induced inactivation of the action potential mechanism. These results identify previously unknown roles of potassium channels in mammalian cerebellar function and motor control. In addition, they provide a previously undescribed animal model of cerebellar ataxia.