Variation and heritability of Hb F and F-cells among beta-thalassemia heterozygotes in Hong Kong

Enhanced fetal hemoglobin (Hb F) production can partially compensate for the lack of adult hemoglobin (Hb A) in patients with beta-thalassemia major or intermedia, and ameliorate the clinical severity of these diseases. To further elucidate factors governing Hb F levels, we evaluated demographic, clinical, laboratory, and genetic characteristics in 241 unrelated adult beta-thalassemia carriers in Hong Kong. They had wide variations in Hb F and F-cell numbers skewing toward higher levels. Individuals who coinherited the Xmn IT-allele in the (G)gamma-globin gene promoter had higher Hb F and more F-cells compared with those lacking the Xmn I T-allele. However, both groups exhibited a similarly wide spread of Hb F and F-cells. The correlation of Hb F and F-cells corresponded well to both linear and exponential models, suggesting multiple mechanisms for Hb F augmentation. The heritabilities of Hb F and F-cells were calculated in 66 families (111 parents who were beta-thalassemia carriers and 82 asymptomatic offspring) to be 0.7 to 0.9. The Xmn I polymorphism accounted for 9% of the Hb F and 13% of the F-cell heritabilities. These results suggest that these family members are well suited for genome wide association studies that will identify genetic loci regulating Hb F production, and likely novel pharmacological targets for reactivating Hb F production in adults.     

Sequence Conservation of the Region Targeted by the Abbott RealTime HBV Viral Load Assay in Clinical Specimens

The Abbott RealTime HBV assay targets the N-terminal region of the S gene. Here we analyzed the sequence variability of the assay target region from >2,100 clinical specimens. Thermodynamic modeling of the percentage of bound primer/probe at the assay annealing temperature was performed to assess the potential effect of sequence variability.     

Comparison of Pyrosequencing,Sanger Sequencing,and Melting Curve Analysis for Detection of Low-Frequency Macrolide-Resistant Mycoplasma pneumoniae Quasispecies in Respiratory Specimens

Macrolide-resistant Mycoplasma pneumoniae (MRMP) is emerging worldwide and has been associated with treatment failure. In this study, we used pyrosequencing to detect low-frequency MRMP quasispecies in respiratory specimens, and we compared the findings with those obtained by Sanger sequencing and SimpleProbe PCR coupled with a melting curve analysis (SimpleProbe PCR). Sanger sequencing, SimpleProbe PCR, and pyrosequencing were successfully performed for 96.7% (88/91), 96.7% (88/91), and 93.4% (85/91) of the M. pneumoniae-positive specimens, respectively. The A-to-G transition at position 2063 was the only mutation identified. Pyrosequencing identified A2063G MRMP quasispecies populations in 78.8% (67/88) of the specimens. Only 38.8% (26/67) of these specimens with the A2063G quasispecies detected by pyrosequencing were found to be A2063G quasispecies by Sanger sequencing or SimpleProbe PCR. The specimens that could be detected by SimpleProbe PCR and Sanger sequencing had higher frequencies of MRMP quasispecies (51% to 100%) than those that could not be detected by those two methods (1% to 44%). SimpleProbe PCR correctly categorized all specimens that were identified as wild type or mutant by Sanger sequencing. The clinical characteristics of the patients were not significantly different when they were grouped by the presence or absence of MRMP quasispecies, while patients with MRMP identified by Sanger sequencing more often required a switch from macrolides to an alternative M. pneumoniae-targeted therapy. The clinical significance of mutant quasispecies should be investigated further with larger patient populations and with specimens obtained before and after macrolide therapy.     

Endothelial-like nitric oxide synthase immunolocalization by using gold nanoparticles and dyes

Immunofluorescence is a biological technique that allows displaying the localization of the target molecule through a fluorescent microscope. We used a combination of gold nanoparticles and the fluorescein isothiocianate, FITC, as optical contrast agents for laser scanning confocal microscopy imaging to localize the endothelial-like nitric oxide synthase in skeletal muscle cells in a three-dimensional tissue phantom at the depth of 4µm. The FITC detected fluorescence intensity from gold-nanoparticles-labelled cells was brighter than the emission intensity from unlabelled cells.OCIS codes: (170.1790) Confocal microscopy, (280.1415) Biological sensing and sensors     

Prostate cancer detection upon transrectal ultrasound-guided biopsy in relation to digital rectal examination and prostate-specific antigen level: what to expect in the Chinese population?

We investigated the prostate cancer detection rates upon transrectal ultrasound (TRUS)-guided biopsy in relation to digital rectal examination (DRE) and prostate-specific antigen (PSA), and risk factors of prostate cancer detection in the Chinese population. Data from all consecutive Chinese men who underwent first TRUS-guided prostate biopsy from year 2000 to 2013 was retrieved from our database. The prostate cancer detection rates with reference to DRE finding and PSA level of < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ were investigated. Multivariate logistic regression analyses were performed to investigate for potential risk factors of prostate cancer detection. A total of 2606 Chinese men were included. In patients with normal DRE, the cancer detection rates were 8.6%, 13.4%, 21.8%, 41.7% and 85.2% in patients with PSA < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ respectively. In patients with abnormal DRE, the cancer detection rates were 12.4%, 30.2%, 52.7%, 80.6% and 96.4% in patients with PSA < 4, 4–10, 10.1–20, 20.1–50 and > 50 ng ml⁻¹ respectively. Older age, smaller prostate volume, larger number of biopsy cores, presence of abnormal DRE finding and higher PSA level were associated with increased risk of prostate cancer detection upon multivariate logistic regression analyses (P < 0.001). Chinese men appeared to have lower prostate cancer detection rates when compared to the Western population. Taking the different risk factors into account, an individualized approach to the decision of TRUS-guided biopsy can be adopted.