Biomedical subjects

S Wu

Publications and source records attributed to S Wu.

At least 127 records · Page 7Linked to original sources

PubMed2000

Cyclic nucleotide-gated channels mediate membrane depolarization following activation of store-operated calcium entry in endothelial cells.

Calcium agonists induce membrane depolarization in endothelial cells through an unknown mechanism. Present studies tested the hypothesis that pulmonary artery endothelial cells express a cyclic nucleotide-gated (CNG) cation channel activated by store-operated calcium entry to produce membrane depolarization. In the whole-cell configuration, voltage-clamped cells revealed a large non-inactivating, outwardly rectifying cationic current in the absence of extra- or intracellular Ca(2+) that was reduced upon replenishment of Ca(2+). The inward current was non-selective for K(+), Na(+), Cs(+), and Rb(+) and was not inhibited by high tetraethylammonium concentrations. cAMP and cGMP stimulated the current and changed the cation permeability to favor Na(+). Moreover, 8-bromo-cAMP stimulated the current in voltage-clamped cells in the perforated patch mode. The cationic current was inhibited by the CNG channel blocker LY83,583, and reverse transcriptase-polymerase chain reaction cloning identified expression of a CNG channel resembling that seen in olfactory neurons. Activation of store-operated calcium entry using thapsigargin increased a current through the CNG channel. Stimulation of the current paralleled pulmonary artery endothelial cell membrane depolarization, and both the current and membrane depolarization were abolished using LY83,583. Taken together, these data demonstrate activation of store-operated calcium entry stimulates a CNG channel producing membrane depolarization. Such membrane depolarization may contribute to slow feedback inhibition of store-operated calcium entry.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Association of the N-acetyltransferase I gene (NATI) with mild and severe substance abuse.

We observed a significant increase in the number subjects carrying the NAT1* 10 allele of the N-acetyl transferasel (NAT1) gene in controls with a MAST-R score of > or = 4 and in subjects with drug and/or alcohol dependence (p=0.003), compared with controls with a MAST-R <4. These results suggest that alterations in the acetylation of one or more CNS compounds may be related to both mild and severe substance abuse.

Adult↗

PubMed2000

Human aspartic protease memapsin 2 cleaves the beta-secretase site of beta-amyloid precursor protein.

The cDNAs of two new human membrane-associated aspartic proteases, memapsin 1 and memapsin 2, have been cloned and sequenced. The deduced amino acid sequences show that each contains the typical pre, pro, and aspartic protease regions, but each also has a C-terminal extension of over 80 residues, which includes a single transmembrane domain and a C-terminal cytosolic domain. Memapsin 2 mRNA is abundant in human brain. The protease domain of memapsin 2 cDNA was expressed in Escherichia coli and was purified. Recombinant memapsin 2 specifically hydrolyzed peptides derived from the beta-secretase site of both the wild-type and Swedish mutant beta-amyloid precursor protein (APP) with over 60-fold increase of catalytic efficiency for the latter. Expression of APP and memapsin 2 in HeLa cells showed that memapsin 2 cleaved the beta-secretase site of APP intracellularly. These and other results suggest that memapsin 2 fits all of the criteria of beta-secretase, which catalyzes the rate-limiting step of the in vivo production of the beta-amyloid (Abeta) peptide leading to the progression of Alzheimer's disease. Recombinant memapsin 2 also cleaved a peptide derived from the processing site of presenilin 1, albeit with poor kinetic efficiency. Alignment of cleavage site sequences of peptides indicates that the specificity of memapsin 2 resides mainly at the S(1)' subsite, which prefers small side chains such as Ala, Ser, and Asp.

Alzheimer Disease↗

PubMed2000

Identification, functional characterization, and regulation of a new cytochrome P450 subfamily, the CYP2Ns.

The screening of liver and heart cDNA libraries from the teleost Fundulus heteroclitus with degenerate oligonucleotide probes to conserved alpha-helical regions in mammalian P450s resulted in the identification of two cDNAs that together represent a novel P450 subfamily, the CYP2Ns. Northern analysis demonstrated that CYP2N1 transcripts are most abundant in liver and intestine, whereas CYP2N2 mRNAs are most abundant in heart and brain. CYP2N1 and CYP2N2 proteins were co-expressed with NADPH-cytochrome P450 oxidoreductase in Sf9 insect cells, and their ability to metabolize arachidonic acid and xenobiotic substrates was examined. Both CYP2N1 and CYP2N2 metabolize arachidonic acid to epoxyeicosatrienoic acids. Epoxidation is highly regio- and enantioselective with preferential formation of (8R,9S)-epoxyeicosatrienoic acid (optical purities are 91 and 90% for CYP2N1 and CYP2N2, respectively) and (11R, 12S)-epoxyeicosatrienoic acid (optical purities are 92 and 70% for CYP2N1 and CYP2N2, respectively). CYP2N1 and CYP2N2 also catalyze the formation of a variety of hydroxyeicosatetraenoic acids. Both P450s have benzphetamine N-demethylase activities but show minimal alkoxyresorufin O-dealkylase activities. To investigate factors affecting CYP2N expression in vivo, CYP2N transcripts were examined following starvation and/or treatment with 12-O-tetradecanoyl phorbol-13-acetate. Intestinal CYP2N1 mRNAs decrease in starved and/or phorbol ester-treated fish, whereas intestinal CYP2N2 transcripts decrease only following phorbol ester treatment. Interestingly, cardiac CYP2N2 expression decreases following phorbol ester treatment but increases following starvation. These results demonstrate that members of this novel P450 subfamily encode early vertebrate forms of arachidonic acid catalysts that are widely expressed and are regulated by environmental factors. Given the wealth of information on the functional role of P450-derived arachidonate metabolites in mammals, we postulate that CYP2N1 and CYP2N2 products have similar biological functions in early vertebrates. The identity of the mammalian orthologue(s) of the CYP2Ns remains unknown.

Amino Acid Sequence↗

PubMed2000

Transforming activity of receptor tyrosine kinase tyro3 is mediated, at least in part, by the PI3 kinase-signaling pathway.

Protein tyrosine phosphorylation is an integral part of cytokine-induced proliferation and differentiation of hematopoietic cells. The authors previously reported cloning and characterization of the receptor tyrosine kinase Tif, also termed Tyro3. Using the yeast 2-hybrid technology, they recently identified that the p85 subunit of phosphatidylinositol 3-kinase (PI3 kinase) interacted with the cytoplasmic domain of Tyro3. On treatment with epidermal growth factor (EGF), NIH3T3 cells expressed EGFR/Tyro3 (a fusion receptor with the extracellular domain from epidermal growth factor receptor and the transmembrane and cytoplasmic domains from Tyro3), and EGFR/Tyro3 was rapidly phosphorylated on tyrosine residues. The interaction between Tyro3 and p85 was also confirmed by glutathione S-transferase (GST) pull-down experiments. Co-immunoprecipitation followed by Western blot analysis revealed that PI3 kinase was associated with and phosphorylated by the activated Tyro3. Tyro3-associated PI3 kinase exhibited an enhanced kinase activity. In addition, EGF treatment of EGFR/Tyro3-expressing cells led to enhanced phosphorylation of Akt, a downstream component of PI3 kinase. Treatment of NIH3T3 cells expressing a full length of rat Tyro-3, but not NIH3T3 cells, with protein S also resulted in phosphorylation of Akt. Soft agar colony assays showed that the addition of EGF to EGFR/Tyro3-transfected cells, but not to the parental NIH3T3 cells, resulted in a concentration-dependent increase in the formation of anchorage-independent colonies. Tyro3-mediated transformation of NIH3T3 cells was significantly blocked by wortmannin, a PI3 kinase-specific inhibitor. Results of these combined studies strongly suggested that the oncogenic transforming ability of Tyro3 was mediated at least in part by the PI3 kinase pathway. (Blood. 2000;95:633-638)

3T3 Cells↗

PubMed2000

Gamma-irradiation induces matrix metalloproteinase II expression in a p53-dependent manner.

Matrix metalloproteinases (MMPs) are a family of proteinases that degrade the basement membrane and have been implicated in promoting tumor metastasis. MMP-2, one member of this family, was recently found to be a p53 target and subject to p53 upregulation. In this study, we examined the correlation between the expression of MMP-2 and the increased expression of p53 after gamma-irradiation. Three human p53-positive cell lines that express wild-type p53, including U2-OS (osteosarcoma), RKO (colon carcinoma), MCF-7 (breast carcinoma), one mouse p53 positive cell line and HepG2 (liver carcinoma), and two p53-negative human cell lines, SAOS-2 (osteosarcoma) and RKO-E6 (colon carcinoma), were used in this study. The MMP-2 activity was analyzed by using gelatin zymography. The p53 level was measured by western blot analysis. Our results show that wild-type p53 induced by ionizing radiation caused a subsequent increase of MMP-2 activity in U2-OS and RKO cells but not in MCF-7, HepG2, SAOS-2, or RKO-E6 cells. These results suggest that the gamma-radiation-induced expression of MMP-2 is dependent on the cell type and presence of functional p53. Thus, ionizing radiation could activate MMP-2 activity in a subset of human cancer cells and may lead to an increase in their metastatic potential.

Animals↗

PubMed2000

Degradation pathways of a peptide boronic acid derivative, 2-Pyz-(CO)-Phe-Leu-B(OH)(2).

The peptide boronic acid derivative 2-Pyz-(CO)-Phe-Leu-B(OH)(2) is a potent inhibitor of 20S proteasome and a proposed anticancer agent. During preformulation studies, the compound presented erratic stability behavior. Efforts were made to isolate and identify the degradation products, thereby helping to identify possible mechanisms for the degradation. The reaction of 2-Pyz-(CO)-Phe-Leu-B(OH)(2) with hydrogen peroxide not only provided a convenient way to isolate the initial degradation products seen from hydrolysis in aqueous buffers but also showed that the major, initial degradation pathway was probably oxidative in nature. The isolated degradation products were characterized by nuclear magnetic resonance spectroscopy, mass spectrometry, and optical rotation dispersion. In the presence of hydrogen peroxide, the boronic acid group was cleaved from 2-Pyz-(CO)-Phe-Leu-B(OH)(2) to give an alcohol with an apparent retention of the original stereochemistry. Subsequent isomerization and further hydrolysis were then seen. Surprisingly, added ascorbate and EDTA accelerated rather than inhibited degradation. Degradation of 2-Pyz-(CO)-Phe-Leu-B(OH)(2) under acidic and basic conditions seemed to be mediated by an initial oxidative degradation pathway similar to that seen with the peroxide.

Ascorbic Acid↗

PubMed2000

Retinoids and ovarian cancer.

Each year, an estimated 26,000 women in the United States are diagnosed with ovarian cancer. During any given year, approximately 14,500 women die from this disease. Ovarian cancer is the seventh most common cancer in women worldwide, after breast, cervix, colon/rectum, stomach, corpus uteri, and lung cancers. In the U.S., ovarian cancer is the second most common gynecologic cancer, and is the fourth leading cause of solid tumor cancer deaths among women. Currently, postoperative chemotherapy of ovarian cancer is still suboptimal. Drug resistance is a common problem resulting in only 20 approximately 30% overall 5-year survival rates. Clearly, continued development of alternative therapeutic strategies is essential for the management of this fatal disease. A number of recent studies have suggested that retinoids may play a potential role as an ovarian cancer chemotherapeutic agent. Retinoids, the natural and synthetic derivatives of vitamin A, have been shown to inhibit the growth of human ovarian cancer cells both in vivo and in culture. This review will initially summarize what is known about the pathological and molecular characteristics of ovarian carcinoma. It will then describe retinoid metabolism and the role of the cellular and nuclear retinoid binding proteins in mediating retinoid action. Following this general review of retinoids and their function, data supporting the role of retinoic acid as a suppresser of ovarian carcinoma cell growth will be presented. Particular attention will be paid to studies suggesting that members of the RB family of proteins and RB2/p130, in particular, are the molecular targets responsible for retinoid mediated inhibition of ovarian carcinoma cell growth. This review will then conclude with a brief discussion of two synthetic retinoids, 4 HPR R(fenretinide) and AHPN/CD437, which have been shown to induce apoptosis in ovarian tumor cells. It will be clear from the studies summarized in this review that retinoids represent a potentially powerful alternative to present chemotherapeutic approaches to the treatment of late stage ovarian cancer.

Antineoplastic Agents↗

PubMed2000

Increased alpha2-adrenergic constriction of isolated arterioles in diffuse scleroderma.

OBJECTIVE: Vasospasm and ischemic organ injury are important in the pathogenesis of systemic sclerosis (SSc; scleroderma). The present study was performed to determine whether SSc arterioles have an intrinsic disturbance in vasoconstrictor activity. METHODS: Skin biopsy samples were obtained from the upper arm of 11 patients with diffuse SSc (clinically uninvolved skin) and 8 age- and sex-matched control subjects. Dermal arterioles were dissected from the biopsy sample and mounted in a myograph for continuous monitoring of arteriolar diameter. The resting internal diameter of control and SSc arterioles was similar (mean +/- SEM 164+/-15 micro and 166+/-18micro, respectively). RESULTS: Dermal arterioles displayed no spontaneous constrictor activity in the absence of stimulation. Vasoconstriction in response to KCI, a receptor-independent activator of smooth muscle, or to phenylephrine, a selective alpha1-adrenergic receptor (alpha1-AR) agonist, was similar in control and SSc arterioles. However, constrictor responses to UK 14,304, a selective alpha2-AR agonist, were increased in SSc compared with control arterioles (maximal constriction responses of 25+/-5% and 67+/-4% [mean +/- SEM] in control and SSc arterioles, respectively; P = 0.000014). Mechanical denudation of the endothelium did not alter reactivity to alpha2-AR activation, indicating that the enhanced constriction in SSc was not mediated by changes in endothelial dilator activity. Indeed, in arterioles constricted with phenylephrine, the endothelial stimuli acetylcholine or bradykinin evoked endothelium-dependent relaxation that was similar in control and SSc arterioles. CONCLUSIONS: Vascular smooth muscle in SSc arterioles displayed a selective increase in alpha2-AR reactivity. The endothelial dilator function appeared normal. Altered activity of smooth muscle alpha2-ARs may contribute to the vasospastic activity that is a prominent feature of the SSc disease process.

Adrenergic alpha-2 Receptor Agonists↗

PubMed2000

Expression analysis and characterization of alternatively spliced transcripts of human IL-7Ralpha chain encoding two truncated receptor proteins in relapsed childhood all.

In the family of cytokines and cytokine receptors, alternative splicing of pre-mRNA is a frequently observed process that generates different protein isoforms from a single genetic locus. The splicing-derived cytokine receptor protein isoforms are mostly soluble receptors or show alterations in their cytoplasmic domain. It is possible that receptor abnormalities or a pathological ratio of different isoforms may contribute to leukaemia by circumventing normal growth factor control or altering the balance of proliferation and differentiation. IL-7 plays a critical role in early stages of both B and T cell maturation. Moreover, it stimulates the expansion of mature T cells including anti-tumour reactive cells as well as a number of T and B cell malignancies underlining its potential importance for deregulated lymphoid proliferation and leukaemogenesis. Here, we present detailed data on the expression of the interleukin 7 receptor alpha chain (IL-7Ralpha) in leukaemic cells from 210 children with acute lymphoblastic leukaemia (ALL) and describe two novel alternatively spliced transcripts of human IL-7Ralpha coding for truncated receptor proteins which are still capable of binding IL-7. IL-7Ralpha mRNA expression was more frequent in more mature pre-B ALL [91% (30/33)] than in common [81% (81/100)] or pro-B ALL [64% (18/28)], or even in T ALL [64% (29/45)]. These results are in concordance with flow cytometric analyses on the proportion of IL-7Ralpha bearing cells among total blast cell population. Our results lead us to assume that splicing derived IL-7Ralpha isoforms play a potential role in modulating IL-7 signal transduction and might be important for the pathogenesis of leukaemia.

Alternative Splicing↗

PubMed2000

The role of nitric oxide in reoxygenation injury of brain microvascular endothelial cells.

OBJECT: The role of nitric oxide (NO) in reperfusion injury of the brain is still controversial. The authors demonstrate that NO injures the brain capillary endothelial cells in a reoxygenation state by the formation of peroxynitrite. MATERIALS AND METHODS: 1) Rat brain capillary endothelial cells (BCECs) were isolated by a two-step enzymatic purification method. The BCECs were identified by the presence of factor VIII. 2) Anaerobic cell preparations were achieved by purging under nitrogen gas with 0.5% CO2 at 37 degrees C for 20 minutes and then reoxygenating in an incubator. To ascertain the degree of BCEC injury after anoxia and reoxygenation, lactate dehydrogenase (LDH) release was measured. The production of NO was measured by the Griess method. 3) The cell-protective effects of superoxide dismutase (SOD), NG-nitro-L-arginine (L-NAME), and S-Methyl-ITU (i-NOS blocker) were studied. RESULTS: 1) Both L-NAME and SOD protected the cells from reoxygenation injury. The protective effect of L-NAME was dose-dependent. S-Methyl-ITU did not protect the cells. 2) The NO production after anoxia/reoxygenation was blocked by L-NAME. CONCLUSION: NO from the BCEC can injure the cells themselves through the formation of peroxynitrite under anoxia/reoxygenation conditions. Increased NO production after anoxia can be attributed to the induction of e-NOS.

Animals↗

PubMed2000

SM5-1: a new monoclonal antibody which is highly sensitive and specific for melanocytic lesions.

Antibodies such as HMB-45 and anti-S100 protein have been widely used as markers of malignant melanoma despite evidence that HMB-45 has a sensitivity of only 67-93% and S100 is nonspecific for melanoma. Using a subtractive immunization protocol in a mouse model of human melanoma, we have generated several monoclonal antibodies with putative specificity for melanoma. After initial screenings, the antibody SM5-1 was chosen because of its intriguing reactivity with melanocytic tumors in both frozen and paraffin sections. The immunohistochemical staining of SM5-1 was studied in paraffin-embedded specimens of 401 melanomas (n = 401; 250 primary melanomas, 151 metastases), melanocytic nevi of the skin (n = 16), nonmelanocytic neoplasms (n = 84). The results were compared with HMB-45 and anti-S100 staining. All antibodies reacted with nevi and 97-99% with primary melanomas. Whereas both SM5-1 and anti-S100 stained 96% (146/151) of melanoma metastases, HMB-45 correctly identified only 83% (126/151). All HMB-45-negative metastases were positive for SM5-1. Whereas neither SM5-1 nor HMB-45 stained any of 84 specimens from 40 different nonmelanocytic neoplasms, anti-S100 was positive in 21/84 (25%). While the staining pattern of SM5-1 was mostly homogeneous, small tumor areas in some metastases remained unstained. Staining with SM5-1 was also observed in perivascular dendritic cells, in plasma cells, some myofibroblasts and the secretion of eccrine sweat glands. Nonactivated epidermal melanocytes, keratinocytes, endothelial cells, smooth muscle cells and peripheral nerves were all negative for SM5-1. These results suggest that SM5-1 is highly specific, as well as sensitive, for melanocytic lesions and is useful in the immunohistochemical evaluation of melanoma.

Animals↗

PubMed2000

Performance of the frameless GyneFix and the TCu380A IUDs in a 3-year multicenter, randomized, comparative trial in parous women.

This study was conducted to evaluate a new and improved inserter (GyneFix) for the anchoring of the Frameless IUD in the uterine cavity. Previous studies conducted with a prototype inserter (Flexigard) did not show fully the advantages of the new anchoring concept because of the shortcomings of the Flexigard inserter and the complexity of the insertion technique. The GyneFix IUD was compared with the TCu380A IUD in six centers in China in approximately 300 women in each group. Only parous women were included in the study. The data from this 3-year, ongoing study demonstrate that the shortcomings of the inserter have been corrected, resulting in better performance and a much reduced rate of failed insertion/expulsion of the frameless and anchored device. The cumulative expulsion rate with the GyneFix IUD was 3.0 at 3 years (annual rates 2.67, 0.33, and 0.0, respectively) compared with a cumulative expulsion rate of 7.38 at 3 years with TCu380A (annual rates 4.63, 1.76, and 1.04, respectively). This difference is statistically significant. The majority of the expulsions with the anchored IUD occurred early in the study, indicating improper anchoring technique. The study also shows that both devices are highly efficacious. No pregnancies occurred with the GyneFix IUD (cumulative pregnancy rate 0.0 at 3 years) versus one pregnancy with TCu380A (cumulative pregnancy rate 0.34 at 3 years). The total use-related discontinuation rate at 3 years was significantly lower with the GyneFix IUD (8.34) than with the TCu380A IUD (14.13) and results in a higher rate of continuation with the GyneFix IUD compared to the TCu380A IUD (90.73 vs 85.25). Neither perforations nor pelvic inflammatory disease cases were encountered with either device in this study, demonstrating the safety of the anchoring system.

Adolescent↗

PubMed2000

Purification and characterization of anticoagulation factors from the venom of Agkistrodon acutus.

Two anticoagulants from five-pace snake (Agkistrodon acutus) venom, anticoagulation factor I (ACF I) and anticoagulation factor II (ACF II), have been purified by a multiple-step chromatography procedure of anion-exchange chromatography, gel permeation chromatography and cation-exchange chromatography. Each of them is shown to be homogeneous as judged by PAGE, SDS-PAGE and mass spectrometry. In vitro, both proteins show equivalent anticoagulant activity, and are devoid of proteolytic, esterolytic, L-amino acid oxidase, phospholipase A, thrombin-like, fibrinolytic, hemorrhagic and lethal activities. They have similar amino acid compositions with similar absorption coeffecients (A(1%)(280)) (30.5 for ACF I and 30.0 for ACF II). Both are disulfide-linked consisting of two 14.7 kD chains for ACF I and two 14.6 kD chains for ACFII. ACF I has a molecular mass of 29,604+/-8 atomic mass units (amu) compared to 29,468+/-6 amu for ACF II, determined by mass spectrometry. The isoelectric points of ACF I and ACF II are 5.7 and 7.0, respectively. We conclude that the two isoforms possess equivalent biological activities with similar amino acid compositions and molecular masses, but different isoelectric points.

Agkistrodon↗

PubMed2000

Transgenic mice expressing surface markers for IFN-gamma and IL-4 producing cells.

The detection of T(H)1-type and T(H)2-type cells directly in situ would be of great value in the study of T(H) development and function in vivo. Transgenic mice expressing human Thy1 and mouse Thy1.1 under the control of the murine IFN-gamma and IL-4 promoters, respectively, have been generated. The hThy1(+) cells represent (with some temporal lag) most of the IFN-gamma-producing CD4(+) T-cells, while the mThy1.1(+) cells represent only a percentage of IL-4 secreting cells. This may be due to mono-allelic expression of the IFN-gamma and IL-4 genes. Since permeabilization is not required for the detection of the transgenic surface markers, these transgenic mice can facilitate the detection of T(H)1-type and T(H)2-type cells by flow cytometry with surface immunofluorescent staining. These surface markers should permit isolation of viable cells according to their T(H) type for adoptive transfer experiments, and may serve as a model system for tracing the development of T(H)1 and T(H)2-type cells in vivo.

3T3 Cells↗

PubMed2000

Antisense IRAK-1 oligonucleotide blocks activation of NF-kappa B and AP-1 induced by IL-18.

Interleukin-18 (IL-18) is a novel proinflammatory cytokine. Most of the immune and inflammatory genes induced by IL-18 are nuclear factor-kappaB (NF-kappaB)- and activator protein-1 (AP-1)-regulated. Interleukin-1 receptor-associated kinase-1 (IRAK-1) has recently been shown to be involved in IL-18-stimulated activation of NF-kappaB and AP-1. The purpose of this study is to investigate the effects of preventing IRAK-1 expression by antisense IRAK-1 oligodeoxynucleotide (ODN) on IL-18-stimulated activation of NF-kappaB and AP-1. Semiquantitative reverse transcription-PCR (RT-PCR) and western blot analysis revealed that antisense IRAK-1 ODN inhibited IRAK-1 mRNA and protein expression (P<0.01). As a result, antisense IRAK-1 ODN attenuated IL-18-induced activation of NF-kappaB and AP-1 as measured by sandwich ELISA in a concentration (1-8 microg ml(-1))- and time (5-24 h)-dependent fashion. These data suggest that antisense IRAK-1 ODN may share a role in the design of antiinflammatory therapeutics.

Enzyme Activation↗

PubMed2000

Simultaneous determination of mecamylamine, nicotine, and cotinine in plasma by gas chromatography-mass spectrometry.

The nicotine receptor antagonist mecamylamine has been shown to increase the efficacy of transdermal nicotine as a pharmacotherapy for tobacco addiction. A product for simultaneous transdermal administration of nicotine and mecamylamine is undergoing clinical trials. In order to carry out pharmacokinetic studies, quantitation of low nanogram per milliliter levels of mecamylamine and nicotine was required. This paper describes a method for simultaneous determination of mecamylamine, nicotine, and the nicotine metabolite, cotinine, in human plasma using gas chromatography-mass spectrometry (GC-MS). Limits of quantitation for mecamylamine, nicotine and cotinine are 2, 1 and 2 ng/ml, respectively.

Cotinine↗

PubMed2000

Simplified process for soybean glycinin and beta-conglycinin fractionation.

A simplification of the pilot-plant scale modified Nagano method yielding two protein fractions, glycinin and beta-conglycinin, by pH adjustment and ultrafiltration membrane separation was developed and compared with our pilot-plant-scale modified Nagano procedure and with a soy protein isolate pilot-plant procedure as our reference process. Two protein fractions, glycinin and beta-conglycinin, were produced from our simplified process and compared to the three protein fractions, glycinin, beta-conglycinin, and an intermediate protein mixture, produced with the modified Nagano method. The pilot-plant yields of glycinin, beta-conglycinin, and intermediate mixture fractions from the modified Nagano method were 9.4, 10.3, and 4.8% [dry basis (db)], respectively. The yield of glycinin fraction of the simplified method was 9.7% (db), and it had a protein content and purity similar to those obtained with the modified Nagano method. The yield of the beta-conglycinin fraction was 19.6% (db), which was twice that of the modified Nagano process. The protein content of beta-conglycinin was 91.6% (db), and the purity was 62.6% of the protein content, which was 9% lower in purity than the modified Nagano method. Process optimization of the simplified method suggested the best operating conditions for the membrane filtration system were 20-25 psi inlet pressure and 200-250 L/min ultrafiltration recirculation speeds.

Antigens, Plant↗