Objective To develop a sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of forsklin in rat plasma.Methods After extraction with methyl tert-butyl ether,chromatographic separation was performed on a C18 column with the mobile phase consisting of water ( 0.1％ formic acid)-acetonitrile in a gradient elution mode.A tandem mass spectrometer equipped with electrospray ionization (ESI) source was used as detector in the positive ion mode.Quantification was performed using multiple reaction monitoring (MRM) with the precursor product combination ions of m/z 411→375.3 and 285→193 for forsklin and diazepam.Results Good linearity was obtained in the 0.5-1000 ng/ml range for the analyte and the analytical method was validated in terms of specificity,precision,accuracy,recovery,stability and matrix effect.These assays gave RSD values always lower than 14.4％ and RE values between -3.5 ％ and 3.8％.In addition,the specificity,extraction recovery,stability and matrix effect were satisfactory.Conclusion Due to its high sensitivity,specificity and simplicity,the method could be used for pharmacokinetic studies of forsklin.

ABSTRACT:In recent years ,there has been high prevalence of murine typhus in Yunnan Province ,People's Republic of China .A large outbreak of murine typhus occurred in Xishuangbanna Prefecture ,Yunnan Province in 2010 .However ,not all cases were confirmed by laboratory assays ;therefore ,field epidemiologic and laboratory investigations of murine typhus in Xishuangbanna Prefecture were conducted in 2011 .Blood samples were collected from clinical diagnostic cases at the acute and convalescence stages of murine typhus in Xishuangbanna Prefecture ,Yunnan Province ,from June to September of 2011 ,and blood and spleen samples were collected from mice sharing the same habitats as the patients .Immunofluorescence assays were used to test for the presence of IgM and IgG antibodies against Rickettsia typhi in sera from patients and mice .Real‐time PCR was used to detect the groEL gene of R .typhi in blood clots from patients at the acute stage and in spleen tissue from mice .A total of 1 157 clinically diagnosed murine typhus cases occurred in Xishuangbanna Prefecture ,Yunnan Province in 2011 ,with an incidence of 102 .10/100 000 .Of these cases ,80 were investigated by laboratory assays and 74 of 80 patients were confirmed to have murine typhus .The coincidence rate between the clinical diagnosis and laboratory detection was 92 .50% .The positivi‐ty rate for IgG antibodies against R .typhi was 14 .0% (14/100) for Rattus f lavipectus ,while the rate by PCR was 9 .0%(9/100) .That laboratory diagnoses confirmed that the severity of the murine typhus outbreak in Xishuangbanna cannot be ig‐nored .The distribution of host animals transmitting R .typhi underscores this conclusion .

Objective To investigate the expression of HOXB4 gene in patients with myelodysplastic syn-dromes(MDS)and its clinical significance in disease progression.Methods mRNA expression of HOXB4 gene in bone marrow mononuclear cells was detected by real-time fluorescence quantitative PCR(RT-qPCR),and the difference in HOXB4 expression was compared between 49 patients with MDS(MDS group)and 35 patients without MDS(group C).The relationship of mRNA expression of HOXB4 with disease characteristics and clinical prognosis was explored in MDS patients.Results mRNA expression level of HOXB4 gene was higher in MDS group than that in group C(P＜0.05).The patients were divided into a high-and a low-expression group according to the median expression level of HOXB4.Leukocyte count was lower in the high-expression group in the low-expression group at the time of initial diagnosis.The proportion of patients with subtypes of primitive cellular hyperplasia,poor prognostic staging and leukemic transformation was higher in the high-expression group than in the low-expression group.Conclusions mRNA expression level of HOXB4 gene has certain relation with AML transformation in MDS patients.