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To investigate the antitumor activities of xanthonic compounds, 10 prenylated xanthone derivatives 2-11 along with their key building block 1,3,6-trihydroxyxanthone 1 were evaluated for their potential cytotoxic activities against HeLa and MDA-MB-231 cancer cell lines. The synthesis afforded a series of prenylated derivatives with typical and new xanthone skeletons. Compounds 2, 3, 4 and 9 were reported for the first time to possess a new scaffold of 2H-xanthene- 3,9-dione. Interestingly, analogues 2 and 3 with the new scaffold demonstrated remarkable in vitro growth inhibitory activities against both the cell lines by displaying a greater cytotoxic potency than the standard drugs used in the assay, namely doxorubicin and cisplatin. In contrast, a dramatic loss of activity was observed for the O-prenylated derivatives 9- 11. These findings have highlighted the therapeutic potential of 2H-xanthene-3,9-dione scaffold to be exploitable as drug lead with specific activity against cervical and breast cancers.

Our recent study on Artocarpus odoratissimus (Moraceae) has resulted in the purification of a new prenylated pyranoflavone derivative artosimmin (1) and traxateryl acetate (2). Details of structural elucidations associated with 1 and 2 are reported by combining 1D, 2D NMR and mass spectrometric methods. Compound 2 is obtained for the first time from this species. Furthermore, the biological assay results exhibited compound 1 to be significantly cytotoxic against cancer cell lines (HL-60 & MCF-7) and also possessed antioxidant properties toward 1,1-diphenyl-2-picrylhydrazyl radical (DPPH).

Fifty-six novel alkyl and/or alkoxy disubstituted 2-(2,3-difluorobiphenyl-4′-yl)-1,3-dioxanes (DFBPD) were prepared. Smectic C and nematic mesophases were exhibited by most of the alkyl-alkoxy homologues. Conversely, most of the dialkyl compounds exhibited smectic C, smectic A and nematic phases. The birefringence (Δn), dielectric anisotropy (Δɛ), spontaneous polarisation and response times of two ferroelectric mixtures formulated from the dioxanyl systems were determined. The birefringence results were compared with eight other groups of mixtures where the materials were based on different core systems. The overall electro-optic properties of the DFBPDs were found to be comparable to the best of the eight most commonly used materials in ferroelectric display devices.

In a 5-year retrospective survey of respiratory syncytial virus (RSV) infections among hospitalized children, 1340 cases were identified of which, 98·4% were children <5 years old with a male:female ratio of 1·5:1. Most cases occurred from April to September showing a significant positive correlation with temperature and relative humidity. Community-acquired infections accounted for 92·5% of the cases with a mean hospital stay of 5 days. The estimated annual incidence of RSV infection requiring hospitalization was 2·5/1000 children <5 years old with a mortality of 0·15% among hospitalized cases. On average, 248 children were admitted each year to the 1400-bed acute regional hospital accounting for an expenditure of HK $1.94 (~US $0.25) million for hospitalization costs which equates to an annual cost in excess of HK $6.67 (~US $0.86) million for the whole of Hong Kong. An RSV vaccine should be a priority.

The cat reporter gene was used to assess expression of two promoters, previously strongly expressed in Escherichia coli, in Brevibacterium sp. R312 strain. The tac promoter (de Boer et al., 1983, Proc. Natl. Acad. Sci. USA 80, 21-25) was poorly expressed in Brevibacterium sp. In contrast, the AatII-SalI fragment of plasmid pYEJ001 (Pharmacia LKB Biotechnology, Sweden) containing two lac operators, a consensus sequence promoter and the cat structural gene clearly revealed chloramphenicol acetyltransferase activity and the presence of a 25,600-kDa protein, corresponding to the monomeric CAT protein, in cell extracts. Copyright 1993, 1999 Academic Press

Background: Dengue haemorrhagic fever (DHF) is a leading cause of hospitalization of children in Southeast Asia and regarded mainly as a problem of childhood. In Singapore, however, both dengue fever (DF) and DHF now occur most frequently in those aged 16-25 years and case fatality rates are higher among adults than children. Objective: To describe adults who died from DHF in Singapore. Study design: The clinical, laboratory and, where performed, autopsy records of adults reported to the Ministry of the Environment to have died from DHF were reviewed. Results: Four of 10 adults had clinical, serological and/or virological evidence of acute dengue virus infection. All 4 patients, who were between 27 and 58 years old, had dengue IgM antibodies. Two of them had elevated dengue IgG antibodies consistent with a recent infection. Dengue type 2 virus was isolated from one of these two patients who had bled into the lungs, skin, pericardial and pleural surfaces and succumbed to shock. The other patient had no evidence of overt bleeding. A third patient, who suffered massive intractable retroperitoneal haemorrhage and shock, seroconverted in the haemagglutination inhibition test for dengue antibodies. The fourth patient had bleeding into her skin, urinary and gastrointestinal tracts, acute pulmonary oedema, ascites and hypotension. Her stillborn baby also had ascites. Conclusion: Deaths from DHF are not mainly a childhood occurrence. Adults do die from severe DHF, whether the infection be primary or secondary.

Rotavirus gastroenteritis should soon be a vaccine-preventable disease. In a 10-year survey of rotavirus gastroenteritis conducted at the Prince of Wales Hospital (PWH), 2281 cases were detected of which 2213 (97%) occurred in children <5 years old. A consistent epidemic occurred each winter during the months of December and January. Of all laboratory-confirmed cases, 78% were community-acquired with a mean hospital stay of 4·7 days. The estimated incidence of rotavirus-attributed hospitalization was 2/1000 children <5 years old. Over the 10 years, rotavirus was responsible for one death, and contributory to three other deaths. On average each year, 195 children <5 years old were hospitalized for a total of 917 days in PWH, accounting for an estimated expenditure of HK$2·8 (~US$0·4) million on hospitalization costs. The annual financial burden for rotavirus gastroenteritis for the whole of Hong Kong could be in excess of HK$9·6 (~US$1·2) million.

The recurrence of cerebral palsy in the same family is uncommon. We, however, report on two families with two or more affected siblings. In both families, numerous potential risk factors were identified including environmental, obstetric, and possible maternal effects. We hypothesize that multiple risk factors may lead to the increased risk of recurrence of cerebral palsy in families. Intrinsic and maternal risk factors should be investigated in all cases of cerebral palsy to properly counsel families on the risk of recurrence. Recent studies of genetic polymorphisms associated with cerebral palsy are considered with reference to our observations in these two families.

Clotting blood contains fibrin-bound thrombin, which is a major source of procoagulant activity leading to clot extension and further activation of coagulation. When bound to fibrin, thrombin is protected from inhibition by antithrombin (AT) + heparin but is neutralized when AT and heparin are covalently linked (ATH). Here, we report the surprising observation that, rather than yielding an inert complex, thrombin-ATH formation converts clots into anticoagulant surfaces that effectively catalyze inhibition of thrombin in the surrounding environment.