Molecular characterization of Hb Hamilton Hill (HBA2: c.388delC), a novel HBA2 variant generating a premature termination codon and truncated HBA2 chain.

In recent years, the identification of α-thalassemias caused by nondeletional mutations has increased significantly due to the advancement of sensitive molecular genetics tools. We report clinical and experimental data for a novel frameshift mutation caused by a single base deletion at position 388 in exon 3 of the α2-globin gene (HBA2: c.388delC; Hb Hamilton Hill), resulting in the phenotype of α-thalassemia (α-thal). Hb Hamilton Hill was identified in an adult female of unknown ethnicity investigated for unexplained microcytosis. Direct DNA sequencing of the HBA2 gene revealed a heterozygous mutation, HBA2: c.388delC, and the molecular effect of this mutation was assessed experimentally using our previously described in vitro model. The experimental analysis involved transfection of a human bladder carcinoma (5637) cell line with expression vectors carrying either HBA2-wild type (HBA2-WT) or HBA2: c.388delC followed by total RNA purification and cDNA synthesis. Both wild type and mutant gene expression was studied and compared at the transcriptional and translational levels using quantitative real time polymerase chain reaction (qReTi-PCR) and immunofluorochemistry (IFC), respectively. Our experimental data showed a significant reduction by 25.0% (p = 0.04) in the transcriptional activity generated from HBA2: c.388delC compared to HBA2-WT. As a result of this base deletion, a frameshift in the open reading frame generates a premature termination codon (PTC) at codon 132 of exon 3 resulting in the formation of a truncated α-globin chain. The truncated α-globin chain, observed by the IFC technique, is most likely unstable and undergoes a rapid turnover resulting in the thalassemic phenotype.

Drotrecogin alfa (activated): real-life use and outcomes for the UK.

INTRODUCTION: In March 2001, the results of the Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis (PROWESS) study were published, which indicated a 6.1% absolute reduction in 28-day mortality. Drotrecogin alfa (activated; DrotAA) was subsequently approved for use in patients with severe sepsis. METHODS: In December 2002, critical care units in England, Wales and Northern Ireland were invited to participate in an audit of DrotAA. Data for each infusion of DrotAA were linked to case mix and outcome data from a national audit. Use of DrotAA was described and a nonrandomized comparison of effectiveness was conducted. RESULTS: 1,292 infusions of DrotAA were recorded in 112 units; 61% commenced during the first 24 hours in the unit. The majority (77%) of patients had three or more organs failing; lung (42%) and abdomen (40%) were the most common primary sites of infection. Crude hospital mortality was high (45%); at 28 days, only 18% had left acute hospital and 19% were still in the unit. For 30%, the full 96-hour infusion was not completed; 24% of infusions were interrupted; 8.1% experienced one or more serious adverse events, of which 77% were serious bleeding events. Of eight relative risks estimated from individually-matched (0.75 to 0.85) and propensity-matched (0.82 to 0.90) controls, seven were consistent with the results of PROWESS. Restricting the analysis to patients receiving DrotAA during the first 24 hours resulted in larger treatment effects (relative risks 0.62 to 0.81). For all matches, similar patterns were seen across subgroups. No effect of DrotAA was seen for two organs failing or lower severity scores, compared with a significant mortality reduction for three or more organs failing or higher severity scores. CONCLUSION: Use of DrotAA was approximately one in 16 for admissions meeting the definition for severe sepsis and with two or more organs failing. Patients receiving DrotAA were younger and more severely ill but were less likely to have serious conditions in their past medical history. Nonrandomized estimates for the effectiveness of DrotAA were consistent with the findings of PROWESS. DrotAA appeared not to be effective in patients with less severe disease.

Development of a multi-pathogen oligonucleotide microarray for detection of Bacillus anthracis.

An oligonucleotide microarray system has been specifically designed to detect and differentiate Bacillus anthracis from other bacterial species present in clinical samples. The pilot-scale microarray initially incorporated probes to detect six common species of bacteria, which were fully evaluated. The microarray comprised long oligonucleotides (50--70-mer) designed to hybridise with the variable regions of the 16S rRNA genes. Probes which hybridised to virulence genes were also incorporated; for B. anthracis, these initially included the pag, lef, cap and vrrA (for partial genotyping) genes. Hybridisation conditions were initially optimised to be run using 5 x SSC, 0.1% SDS, 50 degrees C for 16 h. The detection limits of the microarray were determined under these conditions by titration of chromosomal DNA and unlabelled amplicons followed by hybridisation to determine the levels of sensitivity that could be obtained with the microarray. Two different amplification methodologies were also compared-specific-primer based PCR and random PCR (with the labelling stage incorporated). Higher sensitivity was obtained using specific PCR primers, however, since one of the desired outcomes of a microarray-based detection system was the high discrimination that it offered, random amplification and labelling was used as the amplification method of choice. The length of hybridisation was investigated using a time-course, and 1--2h was found to give optimal and higher signals than 16 h incubation. These results indicate that microarray technology can be employed in a diagnostic environment and moreover, results may be obtained in a similar time-scale to a standard PCR reaction, but with the advantage that no a priori knowledge of the infectious agent is required for detection.