Genetic analysis of the CYP2D6 locus in a Hong Kong Chinese population

BACKGROUND: The cytochrome P450 CYP2D6 enzyme debrisoquine 4-hydroxylase metabolizes many different classes of commonly used drugs, such as tricyclic antidepressants and neuroleptics. Genetic polymorphism of the CYP2D6 gene is responsible for pronounced interindividual and interracial differences in the metabolism of these drugs. The CYP2D6*10 allele and its variants are the most frequent alleles found in Orientals, and they are responsible for diminished debrisoquine 4-hydroxylase activity because of the presence of a C(188)-->T mutation in exon 1. METHODS: One hundred nineteen Hong Kong Chinese subjects were genotyped by means of allele-specific PCR, PCR, and restriction enzyme analysis for 10 CYP2D6 alleles (CYP2D6*1, *2, *4D, *5, *8/*14, *10A, *10B, *15, *16, and J9). RESULTS: CYP2D6*10B was the most prevalent allele, and CYP2D6*10/CYP2D6*10 was the most frequent genotype, representing 41.17% [corrected] of the population. CONCLUSIONS: There was no significant difference in the prevalence of the alleles analyzed between our study and the Chinese populations genotyped previously. This is the largest study in terms of the number of CYP2D6 alleles analyzed in an Oriental population and the first one conducted in a Hong Kong Chinese population.     

State of the art and future directions of scaffold-based bone engineering from a biomaterials perspective

Scaffold-based bone tissue engineering aims to repair/regenerate bone defects. Such a treatment concept involves seeding autologous osteogenic cells throughout a biodegradable scaffold to create a scaffold-cell hybrid that may be called a tissue-engineered construct (TEC). A variety of materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past two decades. This review aims to discuss the advances in bone engineering from a scaffold material point of view. In the first part the reader is introduced to the basic principles of bone engineering. The important properties of the biomaterials and the scaffold design in the making of tissue engineered bone constructs are discussed in detail, with special emphasis placed on the new material developments, namely composites made of synthetic polymers and calcium phosphates. Advantages and limitations of these materials are analysed along with various architectural parameters of scaffolds important for bone tissue engineering, e.g. porosity, pore size, interconnectivity and pore-wall microstructures.     

Comparison of cellular and protein changes in bronchial lavage fluid of symptomatic and asymptomatic patients with red cedar asthma on follow-up examination

Seventeen patients with occupational asthma due to western red cedar had bronchial lavage during follow-up examination after removal from exposure for at least 1 year. Seven patients were asymptomatic while ten continued to have symptoms of asthma requiring treatment. Symptomatic patients had evidence of airway inflammation, as reflected by a significantly higher total cell count, neutrophils and eosinophils, as well as an increase in protein and albumin in their bronchial lavage fluid compared to those without symptoms. Asymptomatic patients had no evidence of airway inflammation in the lavage fluid. There was no correlation between the degree of non-specific bronchial hyperresponsiveness and the number or percentage of inflammatory cells to suggest that cellular infiltration is the sole cause of persistent bronchial hyperresponsiveness.     

Evaluation of Pyrosequencing for Detecting Extensively Drug-Resistant Mycobacterium tuberculosis among Clinical Isolates from Four High-Burden Countries

Reliable molecular diagnostics, which detect specific mutations associated with drug resistance, are promising technologies for the rapid identification and monitoring of drug resistance in Mycobacterium tuberculosis isolates. Pyrosequencing (PSQ) has the ability to detect mutations associated with first- and second-line anti-tuberculosis (TB) drugs, with the additional advantage of being rapidly adaptable for the identification of new mutations. The aim of this project was to evaluate the performance of PSQ in predicting phenotypic drug resistance in multidrug- and extensively drug-resistant tuberculosis (M/XDR-TB) clinical isolates from India, South Africa, Moldova, and the Philippines. A total of 187 archived isolates were run through a PSQ assay in order to identify M. tuberculosis (via the IS6110 marker), and to detect mutations associated with M/XDR-TB within small stretches of nucleotides in selected loci. The molecular targets included katG, the inhA promoter and the ahpC-oxyR intergenic region for isoniazid (INH) resistance; the rpoB core region for rifampin (RIF) resistance; gyrA for fluoroquinolone (FQ) resistance; and rrs for amikacin (AMK), capreomycin (CAP), and kanamycin (KAN) resistance. PSQ data were compared to phenotypic mycobacterial growth indicator tube (MGIT) 960 drug susceptibility testing results for performance analysis. The PSQ assay illustrated good sensitivity for the detection of resistance to INH (94%), RIF (96%), FQ (93%), AMK (84%), CAP (88%), and KAN (68%). The specificities of the assay were 96% for INH, 100% for RIF, FQ, AMK, and KAN, and 97% for CAP. PSQ is a highly efficient diagnostic tool that reveals specific nucleotide changes associated with resistance to the first- and second-line anti-TB drug medications. This methodology has the potential to be linked to mutation-specific clinical interpretation algorithms for rapid treatment decisions.     

Vaginal metastasis presenting as postmenopausal bleeding

Vaginal cancer is rare worldwide and represents 2% of all gynaecological cancers in Singapore. Primary vaginal malignancies are rare and vaginal metastases constitute the majority of vaginal malignancies. Most of these metastases arise from the cervix, endometrium or ovary, although they can also metastasise from distant sites such as the colon, breast and pancreas. We report a rare case of vaginal metastasis in a patient with previous gastric and rectal adenocarcinomas. An 89-year-old woman with a history of gastric and rectal malignancy presented with postmenopausal bleeding. A 2-cm vaginal tumour at the introitus was discovered upon examination. This case demonstrates the importance of performing a gynaecological examination during follow-up for patients with a history of malignancy. The prognosis for vaginal metastasis is poor, as it is often associated with disseminated disease. Depending on the extent of the lesions, radiotherapy or surgery can be considered.     

High mammographic density is associated with an increase in stromal collagen and immune cells within the mammary epithelium

Introduction

Mammographic density (MD), after adjustment for a women’s age and body mass index, is a strong and independent risk factor for breast cancer (BC). Although the BC risk attributable to increased MD is significant in healthy women, the biological basis of high mammographic density (HMD) causation and how it raises BC risk remain elusive. We assessed the histological and immunohistochemical differences between matched HMD and low mammographic density (LMD) breast tissues from healthy women to define which cell features may mediate the increased MD and MD-associated BC risk.

Methods

Tissues were obtained between 2008 and 2013 from 41 women undergoing prophylactic mastectomy because of their high BC risk profile. Tissue slices resected from the mastectomy specimens were X-rayed, then HMD and LMD regions were dissected based on radiological appearance. The histological composition, aromatase immunoreactivity, hormone receptor status and proliferation status were assessed, as were collagen amount and orientation, epithelial subsets and immune cell status.

Results

HMD tissue had a significantly greater proportion of stroma, collagen and epithelium, as well as less fat, than LMD tissue did. Second harmonic generation imaging demonstrated more organised stromal collagen in HMD tissues than in LMD tissues. There was significantly more aromatase immunoreactivity in both the stromal and glandular regions of HMD tissues than in those regions of LMD tissues, although no significant differences in levels of oestrogen receptor, progesterone receptor or Ki-67 expression were detected. The number of macrophages within the epithelium or stroma did not change; however, HMD stroma exhibited less CD206⁺ alternatively activated macrophages. Epithelial cell maturation was not altered in HMD samples, and no evidence of epithelial–mesenchymal transition was seen; however, there was a significant increase in vimentin⁺/CD45⁺ immune cells within the epithelial layer in HMD tissues.

Conclusions

We confirmed increased proportions of stroma and epithelium, increased aromatase activity and no changes in hormone receptor or Ki-67 marker status in HMD tissue. The HMD region showed increased collagen deposition and organisation as well as decreased alternatively activated macrophages in the stroma. The HMD epithelium may be a site for local inflammation, as we observed a significant increase in CD45⁺/vimentin⁺ immune cells in this area.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0592-1) contains supplementary material, which is available to authorized users.     

Extensive Bone Marrow Necrosis in a Case of Acute Myeloid Leukemia Transformed from a Myeloproliferative Neoplasm

Extensive necrosis affecting more than 50%percnt; of the bone marrow is an extremely rare histopathological finding. Relatively little is known about its clinical significance because it is most commonly identified at autopsy – whether it is an independent prognostic marker or whether it is a surrogate marker of underlying disease burden remains unclear. We describe herein a case of a 66-year-old patient with acute myeloid leukemia who presented with acute bone marrow failure and was found to have extensive necrosis. We include presenting clinical features, pathology attained at biopsy, and the challenge of treatment. Bone marrow necrosis is a rare but important clinicopathological entity whose recognition may herald the way for more effective prognostication of underlying disease.Key Words: Bone marrow necrosis, Acute myeloid leukemia, Myeloproliferative neoplasm