A robust analytical method for measurement of phytoestrogens and related metabolites in serum with liquid chromatography tandem mass spectrometry.

A sensitive and robust method using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for quantitation of 13 phytoestrogens and related metabolites in rat serum samples. A new type of column, the Kinetex core-shell C18 column, was applied for rapid separation of the target analytes in 10min. Two enzymes, sulfatase H-1 and gulcuronidase H-5 from Helix pomatia were compared on the efficiency of releasing the conjugated forms of the target analytes to their free forms in serum samples. The method detection limit (MDL) defined as three times the signal to noise ratio in spiked serum matrix-based solutions was in the range of 0.1-3.5ng/mL. The linear dynamic calibration was in the broad range of 0.2-500ng/mL for all target compounds. Thirty-two rat serum samples from the rats that were fed with diets containing either casein or soy protein isolates with various amounts of isoflavones for 8 weeks were analyzed for the target analytes with the developed method. Nine target analytes were detected in the serum samples. Those detectable compounds are all the metabolites of the dietary isoflavones, suggesting that the diet isoflavones were mostly metabolized to their metabolites in rat.

Cardio-Metabolic Disease Risks and Their Associations with Circulating 25-Hydroxyvitamin D and Omega-3 Levels in South Asian and White Canadians.

OBJECTIVES: This study compared cardio-metabolic disease risk factors and their associations with serum vitamin D and omega-3 status in South Asian (SAC) and White Canadians (WC) living in Canada's capital region. METHODS: Fasting blood samples were taken from 235 SAC and 279 WC aged 20 to 79 years in Ottawa, and 22 risk factors were measured. RESULTS: SAC men and women had significantly higher fasting glucose, insulin, homeostasis model assessment for insulin resistance (HOMA-IR), apolipoprotein B (ApoB), ratios of total (TC) to HDL cholesterol (HDLC) and ApoB to ApoA1, leptin, E-selectin, P-selectin, ICAM-1 and omega-3 (p < 0.05), but lower HDLC, ApoA1, vitamin D levels than WC (p < 0.05). SAC women had higher CRP and VEGF than WC women. Adequate (50-74.9 nmol/L) or optimal (≥ 75 nmol/L) levels of 25(OH)D were associated with lower BMI, glucose, insulin, HOMA-IR, TG, TC, low density lipoprotein cholesterol (LDLC), ApoB/ApoA1 ratio, CRP, leptin, and higher HDLC, ApoA1, omega-3 index, L-selectin levels in WC, but not in SAC. Intermediate (>4%-<8%) or high (≥ 8%) levels of omega-3 indices were related to lower E-selectin, P-selectin, ICAM-1 and higher HDLC, 25(OH)D levels in WC, but not in SAC. The BMIs of ≤ 25 kg/m2 were related to lower LDLC, ApoB, VEGF, creatinine and higher 25(OH)D in WC, but not in SAC. CONCLUSIONS: The associations of vitamin D, omega-3 status, BMI and risk factors were more profound in the WC than SAC. Compared to WC, vitamin D status and omega-3 index may not be good predictive risk factors for the prevalence of CVD and diabetes in SAC.

Dietary supplementation with soy isoflavones or replacement with soy proteins prevents hepatic lipid droplet accumulation and alters expression of genes involved in lipid metabolism in rats.

Accumulation of hepatic lipid droplet (HLD) is the hallmark pathology of non-alcoholic fatty liver disease (NAFLD). This study examined the effects of soy isoflavones (ISF) and different amounts of soy proteins on the accumulation of HLD, lipid metabolism and related gene expression in rats. Weanling Sprague-Dawley rats were fed diets containing either 20 % casein protein without (D1) or with (D2) supplemental ISF (50 mg/kg diet) or substitution of casein with increasing amounts of alcohol-washed soy protein isolate (SPI, 5, 10, and 20 %; D3, D4, D5) for 90 days. Dietary casein (20 %) induced accumulation of HLD in female, but not in male rats. Both soy proteins and ISF remarkably prevented the formation of HLD. Soy proteins lowered hepatic total cholesterol and triglyceride in a dose-dependent manner. Interestingly, soy proteins but not ISF significantly increased free fatty acids in the liver of the female rats compared to D1. Proteomic analysis showed that at least 3 enzymes involved in lipogenesis were down-regulated and 7 proteins related to fatty acid ß-oxidation or lipolysis were up-regulated by soy protein over D1. Additionally, 9 differentially expressed proteins identified were related to amino acid metabolism, 5 to glycolysis and 2 to cholesterol metabolism. Dietary ISF and SPI markedly reduced hepatic-peroxisome-proliferator-activated receptor γ2 (PPARγ2) and fat-specific protein 27 (FSP27) in female rats. Overall, this study has shown that partial or full replacement of dietary casein by soy protein or supplementation with soy ISF can effectively prevent the accumulation of HLD. The potential molecular mechanism(s) involved might be due to suppression of lipogenesis and stimulation of lipolysis and down-regulation of PPARγ2 and FSP27. This suggests that consumption of soy foods or supplements might be a useful strategy for the prevention or treatment of fatty liver diseases.

Determination of isoflavones in rat serum using liquid chromatography-tandem mass spectrometry with a highly efficient core-shell column.

Consumption and nutritional supplementation of soy and soy-based products have been linked to health benefits such as lower cholesterol and triglyceride levels, and decreased incidence of cardiovascular disease and diabetes. In this study, we have developed a sensitive, specific, and robust method using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for determination of serum isoflavones. A new highly efficient pentafluorophenyl phase core-shell column was first used to separate all isoflavones within 3 min, a separation time which is comparable to ultra-pressure liquid chromatography (UPLC) and micro-HPLC. A two-enzyme hydrolysis system with sulfatase and ß-glucuronidase has also been developed to improve the efficiency of deconjugation of conjugated isoflavones in serum. The corresponding conjugated isoflavones were used to evaluate recoveries. In addition to duplicates, the method of standard addition was also applied in sample analysis for quality control. The developed method was applied to the analysis of 32 serum samples and was shown to be specific, sensitive and reproducible.

Sex- and age-specific immunomodulatory effects of dietary soya protein isolate and isoflavones in rats.

The present study examined, using rats as a model, the effects of sex and age of exposure to dietary soya components on serum total and soya-specific antibody content. In Expt 1, Sprague-Dawley rats at 50 d of age were fed diets containing 20 % casein or 20 % alcohol-washed soya protein isolate (SPI) with or without supplemental isoflavones (ISF, 250 mg/kg diet) for 70, 190 or 310 d. The offspring were fed the same diets as their parents. In Expt 2, juvenile Sprague-Dawley rats at 30 d of age were fed diets containing 20 % casein with or without supplemental ISF (50 mg/kg diet) or increasing amounts of alcohol-washed SPI (5, 10 or 20 %) for 90 d. Exposure of rats to dietary SPI before the age of 28 d increased serum total IgA and IgM, and induced the production of SPI-specific IgA, IgG, IgM and IgE antibodies. Feeding of juvenile or adult rats with SPI elevated serum total IgA in females, while the opposite occurred in males, and markedly stimulated the production of SPI-specific IgM in females and IgG in males. Our data suggest that the effects of soya proteins and ISF on the production of serum total and SPI-specific antibodies appear to be sex dependent and also related to the age of exposure to soya in rats. However, the physiological significance of these immune responses remains to be determined.

Effect of soy proteins and isoflavones on lipid metabolism and involved gene expression.

Clinical trials and animal studies showed that ingestion of soy proteins improves blood lipid profiles including lowering triglyceride, total and LDL cholesterol levels and increasing HDL cholesterol content. However, the effective components in the soy and the mechanisms involved in the hypolipidemic actions are not fully understood. Increasing evidence from animal studies have suggested that soy components may regulate lipid metabolism by modulating the activities of key transcription factors and thereby changing the downstream gene expression involved in lipogenesis or lipolysis. It has been shown that intake of soy proteins alters the expression of genes for sterol regulatory element binding protein, peroxisomal proliferator activated receptor, and liver X receptor. Dietary soy proteins suppress the DNA binding activities of hepatic nuclear receptors for thyroid hormones and retinoic acid, and alter the activities of key enzymes including cholesterol 7alpha hydroxylase and ATPase/ATP synthase through post-translational protein modifications. This paper reviews the current understanding of the cellular and molecular events by which soy components affect lipid levels, especially focusing on modulation of transcription factors and regulation of gene expression involved in lipid metabolism by soy proteins and associated isoflavones.

Defective expression of Bruton's tyrosine kinase in acute lymphoblastic leukemia.

Bruton's tyrosine kinase (BTK) is a cytoplasmic tyrosine kinase that serves an essential role in B cell signaling and development. We examined the BTK expression profile of primary leukemic cells from infants with newly diagnosed acute lymphoblastic leukemia (ALL) (N = 14) and from pediatric patients with newly diagnosed (N = 10) or relapsed (N = 5) B-lineage ALL. Analysis of BTK protein and mRNA expression in the infant patient cells (N = 14) showed variable levels of BTK expression with the majority of samples having reduced to absent BTK expression. Sequence analysis of reverse transcriptase-polymerase chain reaction (RT-PCR) products of Btk mRNA from infant leukemia cells revealed the presence of aberrant transcripts. These Btk transcripts were characterized by either deletion of exon 16 (delta16) alone or deletion of both exons 15 and 16 (delta15 and 16). These deletions involve exact exon skipping and encode BTK proteins with either a deleted (delta16), or truncated (delta15 and 16) kinase domain. Extension of these Btk transcript sequencing studies to 15 pediatric B-lineage ALL patients revealed expression of exon 16 deleted Btk transcripts in several pediatric patients, however, none of these pediatric patients expressed transcripts with the exon 15 and 16 deletion. Both reduced expression of Btk message and expression of aberrant deleted Btk transcripts would contribute to reduced BTK protein expression and function in B-lineage leukemia cells. Since BTK is required for radiation induced apoptosis, reduced to absent expression of functional BTK in infant ALL cells could contribute to their radiation resistance.

CD95 (APO-1/FAS) deficiency in infant acute lymphoblastic leukemia: detection of novel soluble Fas splice variants.

Fas (APO-1/CD95) is a 45-kDa membrane protein which regulates apoptosis in many lymphoid cell types. In the present study, FAS expression was examined in primary leukemic cells from infants with acute lymphoblastic leukemia (ALL). The cells were resistant to apoptosis induction by an anti-FAS antibody and expressed nearly undetectable amounts of FAS protein. Molecular analysis of FAS transcripts in these cells revealed no detectable expression of full-length Fas mRNA after a single round of reverse transcription and polymerase chain reaction (PCR) amplification (RT-PCR). However, a more sensitive nested RT-PCR analysis revealed alternatively spliced Fas transcripts in three of five infants (60%) with the remaining two infants showing no detectable Fas mRNA expression. The primary sequence variation of Fas mRNA seen in the samples was a previously described variant lacking exon 6 encoding soluble FAS. However, we also detected the presence of several novel alternatively spliced FAS transcripts in the ALL cells. In one patient, we observed a novel spliced form of soluble Fas, which not only lacked exon 6 but also contained an insertion of an alternative exon 7 (exon 7B). In another, a novel exon 4Del FAS mRNA variant was observed, which contained an additional 4-bp deletion at the exon 5/6-splice junction. These variants lack intact transmembrane domains and thus are predicted to encode soluble FAS variants. The low level of expression of functional full length FAS transcripts with corresponding low level of FAS protein expression in the ALL cells contribute to their resistance to CD95-mediated apoptosis.

Genomic studies of the spleen protein tyrosine kinase locus reveal a complex promoter structure and several genetic variants.

Here we show that the gene of the cytoplasmic tyrosine kinase SYK spans a region of 90kb with 13 coding exons, an alternative exon 14 and at least two 5' untranslated regions exons 1a and 1b. 5' RACE (Rapid amplification of cDNA ends) of human Syk cDNAs demonstrated a complex promoter usage and splicing pattern. We identified three common single nucleotide polymorphisms in the exon la promoter region of the Syk gene as well as a variant Syk cDNA haplotype. This haplotype was characterized by a constellation of 5 silent mutations in the Syk cDNA: 1065(C-T), 1302(G-C), 1338(G-A), 1521(C-T) and 1545(T-C). A hypervariable CATATA(n) repeat polymorphism was also localized to the intron between exons 11 and 12. These novel insights into the genomic organization, promoter structure and genetic variability of Syk will serve as a foundation for detailed molecular epidemiological investigation of its potential role in human cancer biology.

Jak3 expression and genomic sequence in pediatric acute lymphoblastic leukemia.

Janus tyrosine kinase 3 (JAK3) is one of several key regulatory enzymes in B-cell precursors which is highly conserved between multiple species. The gene for Jak3 has been mapped to human chromosome 19p12-13.1 and encompasses 23 exons. Constitutively high levels of JAK3 activity may contribute to drug resistance and enhanced clonogenicity of leukemic B-cell precursors from children and infants with acute lymphoblastic leukemia (ALL). As part of a systematic effort to accurately determine the genomic sequence of Jak3 gene in normal and leukemic B-cell precursors, we sequenced a relatively short region of Jak3 spanning two introns, originally termed introns 10 and 11. This genomic sequence appeared in certain RT-PCR products from our analysis of Jak3 gene expression in pediatric, as well as infant, primary ALL cells. Unexpectedly, a gap in the original Jak3 genomic sequence was found in intron 10 across the sequence matching to an Alu element. Furthermore, the sequence obtained from intron 11 did not match at all to that previously reported, and the length of the intron was much larger than expected at 1.1 kb. Homology to Alu elements (three regions, 699 bp total) and a LINE2 element (one region, 189 bp total) were seen across the entire region covering exons 10-12 (2.1 kb total). Two potential single nucleotide polymorphisms (SNPs) were observed in intron 11. No apparent genomic mutation was found across this region in leukemic B-cell precursors from any of the ALL patients examined. This newly described sequence corrects the previous published genomic sequence from this region rather than identifying an insertion or translocation specific to these ALL cases. Our results significantly extend previous efforts to determine the genomic sequence of Jak3 and analyze its expression in childhood pro-B ALL and other forms of ALL.