The low rate of HLA class I molecules on the human embryonic stem cell line HS293 is associated with the APM components' expression level.

Human embryonic stem cells (hESCs) represent a promise for future strategies of tissue replacement. However, there are different issues that should be resolved before these cells can be used in cellular therapies; among others, the rejection of transplantable hESCs as a result of HLA incompatibility between donor cells and recipients. The hESCs exhibit a weak HLA class I expression on the cell surface, but today the responsible mechanisms are unknown. We have analyzed the level expression of HLA class I heavy chain, beta2-microglobulin (beta2-m), and antigen-processing machinery (APM) components (TAP1, TAP2, LMP2, LMP7, and Tapasin) using the HS293 hESC line by real-time quantitative RT-PCR. This analysis has revealed a low expression of beta2-m, HLA-B, and Tapasin, and an absence of expression of: TAP1, TAP2, LMP2, and LMP7 genes in the HS293 hESC line respect to the embryoid bodies (EBs) and the induced stem cells with IFNgamma (with significant differences, p<0.05). The lack or loss of HLA class I molecules due to the down-regulation of the APM components has been frequently found in tumors of different histology as specific mechanisms of immune-evasion. We described for the first time in this report that the hESCs shared similar mechanisms with respect to tumor cells responsible for the weak HLA class I expression on the cell surface.

Direct detection and identification of Arcobacter species by multiplex PCR in chicken and wastewater samples from Spain.

Twenty-two chicken livers, 10 chicken carcasses, and 15 wastewater samples were processed and analyzed for Arcobacter by PCR and traditional culture methods. Samples were enriched for 24 and 48 h, incubated at 30 degrees C under aerobic conditions, and streaked on blood selective media. To determine the best isolation conditions, 20 samples also were processed under microaerophilic conditions at 37 degrees C. Simple and multiplex PCR assays were used directly with enrichment broths and isolated strains. Seventeen Arcobacter strains were isolated from chicken samples, and A. butzleri was the only Arcobacter species identified. The direct PCR assay revealed that 29 of the 32 chicken samples were contaminated with Arcobacter. A. butzleri was the most frequently detected species, although Arcobacter cryaerophilus also was present in some of the samples and Arcobacter skirrowii occasionally was detected. All the wastewater samples were positive by PCR assay for Arcobacter after 24 h of enrichment. A. butzleri and A. cryaerophilus were detected with the multiplex PCR assay. Fourteen Arcobacter strains were isolated from 10 of the 15 water samples analyzed; 7 were identified as A. butzleri and the remaining 7 were A. cryaerophilus. Both for chicken and water samples, Arcobacter detection rate for PCR amplification was higher than for culture isolation. These results indicate the high prevalence of Arcobacter in chicken and wastewater and the inadequacy of available cultural methods for its detection. The species-specific multiplex PCR assay is a rapid method for assessing Arcobacter contamination in chicken and wastewater samples and is a viable alternative to biochemical identification of isolated strains.

Embryonic stem cell bank: a work proposal.

Human embryonic stem cells (hESCs) have an unlimited capacity to proliferate by a self-renewal process and can be differentiated in the three germ layers, opening doors to new clinical therapies to replace missing or damaged cells. The number of research groups and projects using human stem cells has increased largely in the last 5 yr. The creation of stem cell banks is another important step to support the advance of research in this field. Banks must be operated within the strict regulatory famework of good manufacturing practices and good laboratory practices that assure the highest quality standards and must implement a quality system that complies with international quality systems standards. It may also be appropriate to aim at an accreditation in order to assure correct laboratory practices at all times. Stem cell banks should receive the lines previously derived by other groups and hESCs should be provided for groups that justify their use in a research project previously approved by an ethical committee. The assays generally accepted as typical of hESCs together with the microbiological analysis should be performed in order to assure a consistent, reliable, and safe line for the researchers. In this article, the Andalusian Stem Cell Bank proposes a model of a stem cell banking process in order to create a flow diagram of hESC lines and, following the international initiatives in stem cells research, to achieve the full characterization of cells and a standardization of protocols that would simplify the hESCs culture.

Identity tests: determination of cell line cross-contamination.

Cell line cross-contamination is a phenomenon that arises as a result of the continuous cell line culture. It has been estimated that around 20% of the cell lines are misidentified, therefore it is necessary to carry out quality control tests for the detection of this issue. Since cell line cross-contamination discovery, different methods have been applied, such as isoenzyme analysis for inter-species cross-contamination; HLA typing, and DNA fingerprinting using short tandem repeat and a variable number of tandem repeat for intra-species cross-contamination. The cell banks in this sense represent the organizations responsible for guaranteeing the authenticity of cell lines for future research and clinical uses.

[Ribotypes of strains of Pseudomonas aeruginosa in a patient with cystic fibrosis]. / Ribotipos de cepas de Pseudomonas aeruginosa en un paciente afectado de fibrosis quística.

BACKGROUND: Pseudomonas aeruginosa is the major causative agent of respiratory infection in cystic fibrosis (CF) patients, and its presence in sputum is related with important deterioration of lung function in affected patients, thus a methodical monitorization and control of such a microorganism is decisive in the clinical status of the patient. Due to the limited effectiveness of phenotypic subtyping techniques, it is necessary to use molecular characterization methods. MATERIAL AND METHODS: We have studied the respiratory secretions periodically obtained over a period of time of 19 months, screening for total bacterial counts, P. aeruginosa load and genomic analysis of isolates using a ribotyping protocol. RESULTS: This study has showed the chronical and transitory carriage of different strains and the relation of increased bacterial counts with clinical deterioration periods. CONCLUSIONS: We consider that the use of molecular markers can be of great interest in the epidemiological surveillance of P. aeruginosa in CF patients.

Opposite imbalances of distal 14q in two unrelated patients.

Two unrelated children were found to have de novo opposite imbalances for distal 14q. One had a 46,XY, del(14)(q24q32) karyotype and exhibited, like three other patients with similar deletions, a distinctive facial appearance including round face, frontal hypertrichosis, thick eyebrows, horizontal narrow palpebral fissures, a short bulbous nose with a flat root, and mild micrognathia. The other had a 46,XX, dir dup(14)(q22----q32) karyotype and stigmata common to patients with comparable duplications, namely high forehead, sparse eyebrows, prominent overlip, gingival hypertrophy, and overriding fingers. Therefore, it is concluded that each of these imbalances originates a distinct syndrome.

Translocation (Y;19)(q12;q13) and azoospermia.

An azoospermic male with a 46,X,t(Y;19)(q12;q13) karyotype is described. The comparison with 12 similar cases reveals that the Y breakpoints are usually on the long arm whereas the autosomal ones seem to be at random. Since a premeiotic origin is inconsistent with the arrest at diakinesis seen in those cases with meiotic studies, we postulate that a balanced t(Y;A) arises either via a chromatid exchange in the meiotic interphase or through a chromosome exchange in spermiogenesis or at the one cell stage of the zygote.