Etiology of mental retardation in children referred to a tertiary care center: a prospective study.

A prospective assessment following a step-wise protocol in 281 patients with unexplained cognitive delay was used to assess diagnostic possibilities. Diagnostic procedures were complex and required a multidisciplinary approach. One third of diagnoses was established based on clinical history and physical exam only; for another third, clinical history and physical exam provided essential clues for additional investigations; and a third were established by additional investigations only. The likelihood to reach a diagnosis did not depend on the severity of mental retardation. We found that in a tertiary care center, a diagnosis can be established in 1 out of every 2 patients. Clinical history and physical examination are the most important instruments to reach a diagnosis.

Sensitivity of primary R5 HTV-1 to inhibition by RANTES correlates with sensitivity to small-molecule R5 inhibitors.

In approximately 50% of HIV-1 subtype B-infected individuals, progression to AIDS is preceded by the emergence of CXCR4-using (X4) variants, whereas the rest progress to AIDS in the presence of CCR5-using (R5) variants only. In a previous study, we showed that during disease progression in the presence of R5 variants only, HIV-1 variants emerge with a decreased sensitivity to inhibition by RANTES, a natural ligand of CCR5 that inhibits cellular entry of R5 variants. This observation was of potential clinical relevance as HIV-1 small-molecule R5 entry inhibitors are a new class of drugs that, in analogy to RANTES, target the binding and subsequent entry of HIV into the target cell. Here we show that R5 HIV-1 sensitivity to RANTES correlates with sensitivity to the R5 small-molecule inhibitor AD101. HIV-1 small-molecule entry inhibitors are a new class of drugs that target the binding and subsequent entry of HIV into the target cell. Furthermore, we found that R5 variants obtained from individuals who later developed X4 variants were less sensitive to AD101 inhibition compared with R5 variants obtained from individuals who never developed X4 variants. These results may have implications for the evaluation of R5 inhibitors in future clinical trials.

Immunohistochemical detection of melphalan-DNA adducts in colon cancer cells in vitro and human colorectal liver tumours in vivo.

Melphalan is a chemotherapeutic drug that exerts its cytotoxic effect mainly through the formation of DNA adducts. We report the specific immunohistochemical detection and visualisation of melphalan-DNA adducts using the monoclonal antibody MP5/73 in cultured tumour cells and solid tumour tissue from colorectal liver metastases from patients treated with melphalan. The human colon cancer cell lines HT29, SW480 and SW1116, and the rat colon cancer cell line CC531 were exposed to different concentrations of melphalan. In addition, tumour samples from 17 patients with colorectal liver metastases treated by isolated hepatic perfusion with high dose melphalan (200mg) were collected. Cell lines and tumour samples were stained with the MP5/73 antibody against melphalan-DNA adducts and cell viability was determined by an MTT assay. Melphalan-DNA adducts could be visualised by immunohistochemistry in both cultured cells and solid tumour tissue. A correlation between melphalan exposure concentration, the subsequent melphalan-DNA adduct staining intensity, and melphalan cytotoxicity existed for each individual cell line, but the level of both parameters independently differed between cell lines. Specific staining for melphalan-DNA adducts also was feasible in the human solid tumour tissue. There was considerable variation in melphalan-DNA adduct staining, staining intensity, and distribution in the tumour stroma and the tumour epithelium among the different patients. Melphalan-DNA adducts appeared to be more intense in tumour cells at the border of the tumour nodules than in tumour cells in the centre. Thus, visualisation of melphalan-DNA adducts by immunohistochemistry allows the study of distribution of melphalan-DNA adducts in solid tumours.

Ribonuclease H1 maps to chromosome 2 and has at least three pseudogene loci in the human genome.

We have analyzed the genomic structure of ribonuclease H1 (RNase H1) loci in the human genome. Human PAC library screening combined with database searches indicated that several loci are present. The transcribed gene is localized on chromosome 2p25. This was confirmed by RNA analysis of a monochromosomal hybrid cell line that expressed human chromosome 2. These data contradict a previous report, as well as the current Human Genome Project (HGP) annotation, which had placed the gene on chromosome 17p11.2. This location represents a pseudogene. Another highly similar pseudogene is present at a separate locus located more distal on chromosome 17p, while a third pseudogene is localized on chromosome 1q.