Biomedical subjects

K Liu

Publications and source records attributed to K Liu.

At least 37 records · Page 2Linked to original sources

PubMed2003

Analysis of HMW glutenin subunits and their coding sequences in two diploid Aegilops species.

Considerable progress has been made in understanding the structure, function and genetic regulation of high-molecular-weight (HMW) glutenin subunits in hexaploid wheat. In contrast, less is known about these types of proteins in wheat related species. In this paper, we report the analysis of HMW glutenin subunits and their coding sequences in two diploid Aegilops species, Aegilops umbellulata (UU) and Aegilops caudata (CC). SDS-PAGE analysis demonstrated that, for each of the four Ae. umbellulata accessions, there were two HMW glutenin subunits (designated here as 1Ux and 1Uy) with electrophoretic mobilities comparable to those of the x- and y-type subunits encoded by the Glu-D1 locus, respectively. In our previous study involving multiple accessions of Ae. caudata, two HMW glutenin subunits (designated as 1Cx and 1Cy) with electrophoretic mobilities similar to those of the subunits controlled by the Glu-D1 locus were also detected. These results indicate that the U genome of Ae. umbellulata and the C genome of Ae. caudata encode HMW glutenin subunits that may be structurally similar to those specified by the D genome. The complete open reading frames (ORFs) coding for x- and y-type HMW glutenin subunits in the two diploid species were cloned and sequenced. Analysis of deduced amino acid sequences revealed that the primary structures of the x- and y-type HMW glutenin subunits of the two Aegilops species were similar to those of previously published HMW glutenin subunits. Bacterial expression of modified ORFs, in which the coding sequence for the signal peptide was removed, gave rise to proteins with electrophoretic mobilities identical to those of HMW glutenin subunits extracted from seeds, indicating that upon seed maturation the signal peptide is removed from the HMW glutenin subunit in the two species. Phylogenetic analysis showed that 1Ux and 1Cx subunits were most closely related to the 1Dx type subunit encoded by the Glu-D1 locus. The 1Uy subunit possessed a higher level of homology to the 1Dy-type subunit compared with the 1Cy subunit. In conclusion, our study suggests that the Glu-U1 locus of Ae. umbellulata and the Glu-C1 locus of Ae. caudata specify the expression of HMW glutenin subunits in a manner similar to the Glu-D1 locus. Consequently, HMW glutenin subunits from the two diploid species may have potential value in improving the processing properties of hexaploid wheat varieties.

Amino Acid Sequence↗

PubMed2003

The impact of weight change on cardiovascular disease risk factors in young black and white adults: the CARDIA study.

OBJECTIVE: To quantify the relation between weight change and change in blood pressure, lipids and insulin levels, and determine if this relation differs by race or initial level of obesity. DESIGN: Longitudinal cohort study. SETTING AND PARTICIPANTS: Community-based sample of 3325 black and white men and women aged 18-30 y from four centers followed for 10 y. Women pregnant at baseline or 10th year exam and persons without a recorded weight at both exams were excluded. Participants whose baseline BMI was >or=25 kg/m(2) were classified as overweight. Height, weight, HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), fasting triglycerides, fasting insulin, and blood pressure were measured at baseline and Year 10. RESULTS: The mean (s.d.) of weight gained over 10 y was 10.5 (10.0) kg (black men), 11.7 (11.0) (black women), 7.7 (8.0) (white men), and 7.2 (10.0) (white women). An increase in weight was associated with adverse changes in all factors in all race-sex groups. For example, a 9.1 kg (20-lb) weight increase in persons not overweight at baseline predicted an increase in LDL-C ranging from 0.23 mmol/l in black women to 0.28 mmol/l in black men and a decrease in HDL-C from 0.09 mmol/l (white women) to 0.11 mmol/l (white men) (all P<0.0001). The estimated change in triglycerides was greater in white than in black participants (P<0.02); no other racial differences were found. Changes in triglycerides (P<0.00001) and fasting insulin (P=0.004) were greater in men than in women. Only for LDL-C was a weight change-associated increase significantly different (greater, P<0.001) for nonoverweight persons than for those overweight at baseline. None of these associations were highly specific. Mean levels of LDL-C, HDL-C, and systolic blood pressure improved among all those who lost or did not gain weight. CONCLUSIONS: A 10 y weight gain in young adults of both races and sexes tends to confer adverse changes in their levels of LDL-C, HDL-C, triglycerides, fasting insulin, and blood pressure. This effect occurs regardless of initial weight, age, race, or gender.

Adolescent↗

PubMed2003

INTERMAP: background, aims, design, methods, and descriptive statistics (nondietary).

Blood pressure (BP) above optimal (< or =120/< or =80 mmHg) is established as a major cardiovascular disease (CVD) risk factor. Prevalence of adverse BP is high in most adult populations; until recently research has been sparse on reasons for this. Since the 1980s, epidemiologic studies confirmed that salt, alcohol intake, and body mass relate directly to BP; dietary potassium, inversely. Several other nutrients also probably influence BP. The DASH feeding trials demonstrated that with the multiple modifications in the DASH combination diet, SBP/DBP (SBP: systolic blood pressure, DBP: diastolic blood pressure) was sizably reduced, independent of calorie balance, alcohol intake, and BP reduction with decreased dietary salt. A key challenge for research is to elucidate specific nutrients accounting for this effect. The general aim of the study was to clarify influences of multiple nutrients on SBP/DBP of individuals over and above effects of Na, K, alcohol, and body mass. Specific aims were, in a cross-sectional epidemiologic study of 4680 men and women aged 40-59 years from 17 diverse population samples in China, Japan, UK, and USA, test 10 prior hypotheses on relations of macronutrients to SBP/DBP and on role of dietary factors in inverse associations of education with BP; test four related subgroup hypotheses; explore associations with SBP/DBP of multiple other nutrients, urinary metabolites, and foods. For these purposes, for all 4680 participants, with standardized high-quality methods, assess individual intake of 76 nutrients from four 24-h dietary recalls/person; measure in two timed 24-h urine collections/person 24-h excretion of Na, K, Ca, Mg, creatinine, amino acids; microalbuminuria; multiple nutrients and metabolites by nuclear magnetic resonance and high-pressure liquid chromatography. Based on eight SBP/DBP measurements/person, and data on multiple possible confounders, utilize mainly multiple linear regression and quantile analyses to test prior hypotheses and explore relations of multiple dietary and urinary variables to SBP/DBP of individuals. The 4680 INTERMAP participants are equally divided across four age/gender strata: diverse in ethnicity, education, occupation, physical activity; use of cigarettes, alcohol; diagnosed high BP, CVD, diabetes; CVD family history; women vary in parity, use of contraceptive medication and hormone replacement therapy.

Blood Pressure↗

PubMed2003

Higher blood pressure in middle-aged American adults with less education-role of multiple dietary factors: the INTERMAP study.

Extensive evidence exists that an inverse relation between education and blood pressure prevails in many adult populations, but little research has been carried out on reasons for this finding. A prior goal of the INTERMAP Study was to investigate this phenomenon further, and to assess the role of dietary factors in accounting for it. Of the 4680 men and women aged 40-59 years, from 17 diverse population samples in Japan, People's Republic of China, UK, and USA, a strong significant inverse education-BP relation was manifest particularly for the 2195 USA participants, independent of ethnicity. With participants stratified by years of education, and assessment of 100+ dietary variables from four 24-h dietary recalls and two 24-h urine collections/person, graded relationships were found between education and intake of many macro- and micronutrients, electrolytes, fibre, and body mass index (BMI). In multiple linear regression analyses with systolic BP (SBP) and diastolic BP (DBP) of individuals the dependent variables (controlled for ethnicity, other possible nondietary confounders), BMI markedly reduced size of education-BP relations, more so for women than for men. Several nutrients considered singly further decreased size of this association by > or =10%: urinary 24-h Na and K excretion, Keys dietary lipid score, vegetable protein, fibre, vitamins C and B6, thiamin, riboflavin, folate, calcium, magnesium, and iron. Combinations of these dietary variables and BMI attenuated the education-SBP inverse coefficient by 54-58%, and the education-DBP inverse coefficient by 59-67%, with over half these effects attributable to specific nutrients (independent of BMI). As a result, the inverse education-BP coefficients ceased to be statistically significant. Multiple specific dietary factors together with body mass largely account for the more adverse BP levels of less educated than more educated Americans. Special efforts to improve eating patterns of less educated strata can contribute importantly to overcoming this and related health disparities in the population.

Adult↗

PubMed2003

Association of education with dietary intake among young adults in the bi-ethnic Coronary Artery Risk Development in Young Adults (CARDIA) cohort.

OBJECTIVE: To examine associations of changes in dietary intake with education in young black and white men and women. DESIGN: The Coronary Artery Risk Development in Young Adults (CARDIA) study, a multi-centre population-based prospective study. Dietary intake data at baseline and year 7 were obtained from an extensive nutritionist-administered diet history questionnaire with 700 items developed for CARDIA. SETTING: Participants were recruited in 1985-1986 from four sites: Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California. SUBJECTS: Participants were from a general community sample of 703 black men (BM), 1006 black women (BW), 963 white men (WM) and 1054 white women (WW) who were aged 18-30 years at baseline. Analyses here include data for baseline (1985-1986) and year 7 (1992-1993). RESULTS: Most changes in dietary intake were observed among those with high education (>or=12 years) at both examinations. There was a significant decrease in intake of energy from saturated fat and cholesterol and a significant increase in energy from starch for each race-gender group (P<0.001). Regardless of education, taste was considered an important influence on food choice. CONCLUSION: The inverse relationship of education with changes in saturated fat and cholesterol intakes suggests that national public health campaigns may have a greater impact among those with more education.

Adolescent↗

PubMed2002

Establishment of a hepatocellular carcinoma cell line with unique metastatic characteristics through in vivo selection and screening for metastasis-related genes through cDNA microarray.

PURPOSE: To establish a hepatocellular carcinoma (HCC) cell line from lung metastatic lesions of human HCC in nude mice so as to provide a suitable model for the study of lung-metastasis-related molecular mechanisms. METHODS: HCC clone cells MHCC97-H were inoculated into BALB/c nude mice, and the pulmonary metastatic lesions were harvested and re-implanted into nude mice for the second round of in vivo selection. The same procedure was repeated twice. A new cell line from the third round of lung metastases was established. RESULTS: A human HCC cell line with unique metastatic characteristics was established by in vivo selection. This cell line, designated as HCCLM3, was polygonal epithelial cell with hypotriploid karyotype and population doubling time of 34.9 h. The cells were positive for alpha fetoprotein (AFP), albumin, cytokeratin 8 (CK8), and negative for hepatitis B surface antigen (HBsAg) by immunocytochemistry. Fluorescence polymerase chain reaction (PCR) showed HBV DNA integration in the cellular genome. When 5 x 10(6) cells were injected subcutaneously into nude mice, tumorigenicity was 100%, with a latency period of 11+/-1 days. Five weeks after s.c. injection, the pulmonary metastatic rate was 100%, the median number of lung metastases being 121 per mouse. After orthotopic implantation of tumor tissue into nude mouse liver for 35 days, widespread loco-regional and distant metastases occurred, with 100% abdominal wall metastases, 80% intra-abdominal cavity metastases, 100% intrahepatic metastases, 70% diaphragm metastases, and 100% pulmonary metastases. The median number of lung metastatic lesions was 268 per mouse. Gene expression profile of HCCLM3 was compared by cDNA microarray with MHCC97-L, a clonal cell strain from the same parental cell line but with low metastatic potential; 25 differentially expressed genes were identified, 18 of which showed decreased expression and seven increased expression in HCCLM3, including the decreased expression of cell cycle control gene Rb2, mismatch repair gene hMSH2, and signal transduction gene protein kinase C beta2, and increased expression of signal transduction gene MAP kinase, kinase 6. CONCLUSIONS: A new HCC cell line characterized by high pulmonary metastases via s.c. and orthotopic inoculation was established, which provides a new model for the study of liver cancer metastasis. Its gene expression profile could help in the understanding of the mechanism of metastasis and provide potential targets for anti-metastasis intervention.

Animals↗

PubMed2002

Interplays between genetic and environmental mechanisms trigger tumorigenic VEGF signalling in human HCC cell lines: pilot study.

The 'angiogenic switch' concept has been used to discover various pro- and anti-angiogenic molecules as pharmacotherapeutic strategies for cancers and other ischemic and inflammatory diseases; however, surprisingly little is known about the 'tumor angiogenic switch' in response to complex interplay between environmental and genetic mechanisms that are most importantly, hypothesis-driven, largely unsolved at the postgenomic level. The present study's aim is to identify those interplays between the expressing green fluorescence protein (EGFP) transcript and redox-driven vascular endothelial growth factor (VEGF) upstream mechanisms that influence tumorigenic VEGF signalling, by using multifactorial orthogonal statistical analyses, the non-transfected and transfected human hepatocellular carcinoma (HCC) cell lines, and quantitative 'sandwich' Elisa immunoassays. The unique results indicate valuable findings on the postgenomic level as follows. Fusion of the EGFP significantly triggers tumorigenic VEGF signalling in three E3-, F11- and A(3-1)-transfected human HCC cell lines, compared with the parental EGFP-free malignant hepatocellular carcinoma (MHCC)1 cell line; Redox-regulated VEGF upstream mechanism interplays dramatically mediate dual responses, either down- or upregulating tumorigenic VEGF signalling, which depends on individual post-transcriptional regulation or upstream modification of the VEGF promoter in the three MHCC1, SMCC7721 and doxorubicin-resistance 7402/D+ non-transfected human HCC cell lines; and mechanism-based strategies for stimulating beta-adrenergic and P2-purinergic signal transduction and counteracting O2 and Ca2+-inflow significantly trigger tumorigenic VEGF signalling in ATRA/ATRP-driven networks, compared with controls of the non-transfected cell types examined. The contrast data offer first pilot paradigms of searching for hypothesis-driven multifactorial interplays on tumorigenic VEGF signalling, which are valuable for further deciphering postgenome-wide VEGF upstream regulatory networks of switching on the tumor angiogenesis, and developing mechanism-based novel pharmacotherapeutic strategies.

Carcinoma, Hepatocellular↗

PubMed2002

The chemical syntheses and bioactivities of novel peptide-based endothelin antagonists.

Endothelin antagonists, novel tripeptides containing a series of unnatural amino acids, were synthesized and characterized. A linear peptide BQ-485, perhydroazepin-1-yl-L-leucyl (1)-D-tryptophanyl (2)-D-tryptophan (3), was selected as the parent compound. The introduction of D-Phe derivatives into these peptidic ET antagonists resulted in potent activity against the contraction of rat aortic smooth muscles induced by ET-1 (10 nM) which activated the ET receptors. Among these compounds, 15 tripeptides had high enough antagonistic activity at the level of 10(-7) mol/L (IC50). The activity of three compounds was 10(-6) mol/L (IC50). These HIM-CO-Leu-D-Trp-D-Phe(-R)-OH compounds as ETA antagonists may provide a tool for the development of therapeutic agents in the treatment of putative ET-1-related disorders.

Animals↗

PubMed2002

Epidemiology survey of rhegmatogenous retinal detachment in Beixinjing District, Shanghai, China.

PURPOSE: To investigate the recent incidence and related risk factors of rhegmatogenous retinal detachment (RRD) in Chinese people. METHODS: This study was an incidence survey based on data for 108,132 persons in Beixinjing District, Shanghai, China. Patients with RRD were inpatients, outpatients, and patients from the local health network. Patients with RRD were compared with control subjects who were matched by sex, age, and block of residence. Previous population data were used to estimate the whole and specific incidence of RRD. Some factors relevant to the incidence of RRD were found by comparing the patients with RRD with the control subjects. RESULTS: Between January 1996 and December 1999, 61 cases of RRD occurred. The annual incidence of RRD was 11.3 cases per 100,000 population in 1996, 14.1 cases per 100,000 population in 1997, 14.1 cases per 100,000 population in 1998, and 17.9 cases per 100,000 population in 1999. The average annual incidence was 14.4 cases per 100,000 population (95% confidence interval, 10.0-18.6). There were 29 males and 32 females with RRD. The incidence of RRD among persons older than 40 years was high, especially among those between 40 and 59 years of age. The proportion of individuals with high myopia (more than -6 diopters) was significantly higher in the patient group than in the control group (P < 0.001). CONCLUSION: The annual incidence of RRD among a local Chinese population increased over 4 years. This disease is strongly associated with high myopia and age.

Adolescent↗

PubMed2002

Effect of food on early drug exposure from extended-release stimulants: results from the Concerta, Adderall XR Food Evaluation (CAFE) Study.

Stimulant therapy is the mainstay of treatment for children, adolescents and adults with attention-deficit/hyperactivity disorder (ADHD). Once-daily, extended-release oral formulations offer long acting control of symptoms by modifying drug delivery and absorption. In particular, consistency in early drug exposure is important for symptom control during school or work hours. Because these once-daily formulations are usually taken in the morning, the timing of the doses with breakfast is important. This study compared the effect of a high-fat breakfast on early drug exposure from a morning dose of two extended-release stimulant formulations: the osmotic-controlled OROS tablet of methylphenidate HCI (CONCERTA) and the capsule containing extended-release beads of mixed amphetamine salts (ADDERALL XR). The study had a single-dose, open-label, randomised, four-treatment, crossover design in which healthy subjects received either 36 mg CONCERTA or 20 mg ADDERALL XR in the morning after an overnight fast or a high-fat breakfast. Serial blood samples were collected over 28h to determine plasma concentrations of methylphenidate and amphetamine. The food effect on early drug exposure and the pharmacokinetic profiles up to 8 h after dosing of the two extended-release stimulants were directly compared using partial area (AUC(p4h), AUC(p6h) and AUC(p8h)) fed/fasted ratios. Amphetamine concentrations were markedly lower when the subjects had eaten breakfast, resulting in lower early drug exposures (p < 0.0001). By contrast, methylphenidate concentrations over the same 8 h were unaffected by breakfast, providing consistent levels of early drug exposure. Therefore, as a child's or adult's eating pattern varies, methylphenidate exposure over the first 8 h would be expected to have less day-to-day variation compared with amphetamine exposure. The osmotic-controlled OROS tablet provides a reliable and consistent delivery of methylphenidate HCI, independent of food, for patients with ADHD.

Absorption↗

PubMed2001

Local uptake of (14)C-labeled acetate and butyrate in rat brain in vivo during spreading cortical depression.

Spreading depression severely disrupts ion homeostasis, causes sensory neglect and motor impairment, and is associated with stroke and migraine. Glucose utilization (CMR(glc)) and lactate production rise during spreading depression, but the metabolic changes in different brain cell types are unknown. Uptake of (14)C-labeled compounds known to be preferentially metabolized by the glial tricarboxylic acid cycle was, therefore, examined during unilateral KCl-induced spreading cortical depression in conscious, normoxic rats. [(14)C]Metabolites derived from [(14)C]butyrate in K+ -treated tissue rose 21% compared to that of untreated contralateral control cortex, whereas incorporation of H(14)CO(3) into metabolites in K+ -treated tissue was reduced to 86% of control. Autoradiographic analysis showed that laminar labeling of cerebral cortex by both (14)C-labeled acetate and butyrate was elevated heterogeneously throughout cortex by an average of 23%; the increase was greatest (approximately 40%) in tissue adjacent to the K+ application site. Local uptake of acetate, butyrate, and deoxyglucose showed similar patterns, and monocarboxylic acid uptake was highest in the structures in which apparent loss of labeled metabolites of [6-(14)C]glucose was greatest. Enhancement of net uptake of acetate and butyrate in cerebral cortex during spreading depression is tentatively ascribed to increased astrocyte metabolism.

Acetates↗

PubMed2001

Transduction of an IL-2 gene into human melanoma-reactive lymphocytes results in their continued growth in the absence of exogenous IL-2 and maintenance of specific antitumor activity.

IL-2-dependent activated cells undergo apoptotic death when IL-2 is withdrawn either in vitro or after in vivo cell transfer. To attempt to sustain their survival after IL-2 withdrawal, melanoma-reactive human T lymphocytes were retrovirally transduced with an exogenous human IL-2 gene. Transduced PBMC and cloned CD8+ T cells produced IL-2 and maintained viability after IL-2 withdrawal. Upon restimulation, IL-2 transductants proliferated in the absence of exogenous IL-2 and could be actively grown, and their survival could be maintained without added IL-2 for over 8 wk. PBMCs similarly transduced with a control vector did not produce IL-2 and failed to proliferate in the absence of IL-2. A CD8+ T cell clone, when transduced with an IL-2 gene, manifested the same phenotypes as PBMCs in the absence of exogenous IL-2. Furthermore, an Ab reactive with the alpha-chain of IL-2R complex reduced the viability mediated by IL-2 secretion of the IL-2 transductants. Moreover, transduction of an IL-2 gene did not affect the high degree of recognition and specificity of transductants against melanoma targets. These tumor-reactive IL-2 transductants may be valuable for in vitro studies and for improved adoptive transfer therapies for patients with metastatic melanoma.

Autocrine Communication↗

PubMed2001

Leg symptoms in peripheral arterial disease: associated clinical characteristics and functional impairment.

CONTEXT: Persons with lower-extremity peripheral arterial disease (PAD) are often asymptomatic or have leg symptoms other than intermittent claudication (IC). OBJECTIVE: To identify clinical characteristics and functional limitations associated with a broad range of leg symptoms identified among patients with PAD. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 460 men and women with PAD and 130 without PAD, who were identified consecutively, conducted between October 1998 and January 2000 at 3 Chicago-area medical centers. MAIN OUTCOME MEASURES: Ankle-brachial index score of less than 0.90; scores from 6-minute walk, accelerometer-measured physical activity over 7 days, repeated chair raises, standing balance (full tandem stand), 4-m walking velocity, San Diego claudication questionnaire, Geriatric Depression Score Short-Form, and the Walking Impairment Questionnaire. RESULTS: All groups with PAD had poorer functioning than participants without PAD. The following values are for patients without IC vs those with IC. Participants in the group with leg pain on exertion and rest (n = 88) had a higher (poorer) score for neuropathy (5.6 vs 3.5; P<.001), prevalence of diabetes mellitus (48.9% vs 26.7%; P<.001), and spinal stenosis (20.8% vs 7.2%; P =.002). The atypical exertional leg pain/carry on group (exertional leg pain other than IC associated with walking through leg pain [n = 41]) and the atypical exertional leg pain/stop group (exertional leg pain other than IC that causes one to stop walking [n = 90]) had better functioning than the IC group. The group without exertional leg pain/inactive (no exertional leg pain in individual who walks </=6 blocks per week [n = 28]) and the leg pain on exertion and rest group had poorer functioning than those with IC. Adjusting for age, sex, race, and comorbidities and compared with IC, participants with atypical exertional leg pain/carry on achieved a greater distance on the 6-minute walk (404.3 vs 328.5 m; P<.001) and were less likely to stop during the 6-minute walk (6.8% vs 36%; P =.002). The group with pain on exertion and rest had a slower time for completing 5 chair raises (13.5 vs 11.9 seconds; P =.009), completed the tandem stand less frequently (37.5% vs 60.0%; P =.004), and had a slower 4-m walking velocity (0.80 vs 0.90 m/s; P<.001). CONCLUSIONS: There is a wide range of leg symptoms in persons with PAD beyond that of classic IC. Comorbid disease may contribute to these symptoms in PAD. Functional impairments are found in every PAD symptom group, and the degree of functional limitation varies depending on the type of leg symptom.

Aged↗

PubMed2001

Solid-state NMR studies of the secondary structure of a mutant prion protein fragment of 55 residues that induces neurodegeneration.

The secondary structure of a 55-residue fragment of the mouse prion protein, MoPrP(89-143), was studied in randomly aggregated (dried from water) and fibrillar (precipitated from water/acetonitrile) forms by (13)C solid-state NMR. Recent studies have shown that the fibrillar form of the P101L mutant of MoPrP(89-143) is capable of inducing prion disease in transgenic mice, whereas unaggregated or randomly aggregated samples do not provoke disease. Through analysis of (13)C chemical shifts, we have determined that both wild-type and mutant sequence MoPrP(89-143) form a mixture of beta-sheet and alpha-helical conformations in the randomly aggregated state although the beta-sheet content in MoPrP(89-143, P101L) is significantly higher than in the wild-type peptide. In a fibrillar state, MoPrP(89-143, P101L) is completely converted into beta-sheet, suggesting that the formation of a specific beta-sheet structure may be required for the peptide to induce disease. Studies of an analogous peptide from Syrian hamster PrP verify that sequence alterations in residues 101-117 affect the conformation of aggregated forms of the peptides.

Amino Acid Sequence↗

PubMed2001

Polycyclic aromatic hydrocarbon (PAH) emissions from a coal-fired pilot FBC system.

Due to the extensive amount of data suggesting the hazards of these compounds, 16 polycyclic aromatic hydrocarbons (PAHs) are on the Environmental Protection Agency (EPA) Priority Pollutant List. Emissions of these PAHs in the flue gas from the combustion of four coals were measured during four 1000h combustion runs using the 0.1MW heat-input (MWth) bench-scale fluidized bed combustor (FBC). An on-line sampling system was designed for the 16 PAHs, which consisted of a glass wool filter, condenser, glass fiber filter, Teflon filter, and a Tenax trap. The filters and Tenax were extracted by methylene chloride and hexane, respectively, followed by GC/MS analysis using the selective ion monitoring (SIM) mode. In this project, the effects of operating parameters, limestone addition, chlorine content in the coal, and Ca/S molar ratio on the emissions of PAHs were studied. The results indicated that the emissions of PAHs in an FBC system are primarily dependent on the combustion temperature and excess air ratio. The injection of secondary air with high velocity in the freeboard effectively reduces PAH emissions. The addition of extra limestone can promote the formation of PAHs in the FBC system. Chlorine in the coal can possibly lead to large benzene ring PAH formation during combustion. The total PAH emission increases with an increase in the sulfur content of coal. Incomplete combustion results in PAHs with four or more benzene rings. High efficiency combustion results in PAHs with two or three benzene rings.

Air↗

PubMed2001

Relationship of blood pressure to 25-year mortality due to coronary heart disease, cardiovascular diseases, and all causes in young adult men: the Chicago Heart Association Detection Project in Industry.

BACKGROUND: Data are limited on blood pressure (BP) in young adults and long-term mortality. Moreover, screening and hypertension treatment guidelines have been based mainly on findings for middle-aged and older populations. This study assesses relationships of BP measured in young adult men to long-term mortality due to coronary heart disease (CHD), cardiovascular diseases (CVD), and all causes. METHODS: This cohort from the Chicago Heart Association Detection Project in Industry included 10 874 men aged 18 to 39 years at baseline (1967-1973), not receiving antihypertensive drugs, and without CHD or diabetes. Relationship of baseline BP to 25-year CHD, CVD, and all-cause mortality was assessed. RESULTS: Age-adjusted association of systolic BP to CHD mortality was continuous and graded. Multivariate-adjusted CHD hazard ratios (HRs) for 1 SD higher systolic BP (15 mm Hg) and diastolic BP (10 mm Hg) were 1.26 (95% confidence interval [CI], 1.11-1.44) and 1.17 (95% CI, 1.01-1.35), respectively. Compared with the Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure stratum with normal BP (and lowest mortality rates), the large strata with high-normal BP and stage 1 hypertension had 25-year absolute risks for death of 63 and 72 per 1000, respectively, and absolute excess risks of 10 and 20 per 1000, respectively; accounted for 59.8% of all excess CHD, CVD, and all-cause mortality; and were estimated to have life expectancy shortened by 2.2 and 4.1 years, respectively. CONCLUSIONS: In young adult men, BP above normal was significantly related to increased long-term mortality due to CHD, CVD, and all causes. Population-wide primary prevention, early detection, and control of higher BP are indicated from young adulthood on.

Adolescent↗

PubMed2001

Augmentation in expression of activation-induced genes differentiates memory from naive CD4+ T cells and is a molecular mechanism for enhanced cellular response of memory CD4+ T cells.

In an attempt to understand the molecular basis for the immunological memory response, we have used cDNA microarrays to measure gene expression of human memory and naive CD4+ T cells at rest and after activation. Our analysis of 54,768 cDNA clones provides the first glimpse into gene expression patterns of memory and naive CD4+ T cells at the genome-scale and reveals several novel findings. First, memory and naive CD4+ T cells expressed similar numbers of genes at rest and after activation. Second, we have identified 14 cDNA clones that expressed higher levels of transcripts in memory cells than in naive cells. Third, we have identified 135 (130 known genes and 5 expressed sequence tags) up-regulated and 68 (42 known genes and 26 expressed sequence tags) down-regulated cDNA clones in memory CD4+ T after in vitro stimulation with anti-CD3 plus anti-CD28. Interestingly, the increase in mRNA levels of up-regulated genes was greater in memory than in naive CD4+ T cells after in vitro stimulation and was higher with anti-CD3 plus anti-CD28 than with anti-CD3 alone in both memory and naive CD4+ T cells. Finally, the changes in expression of actin and cytokine genes identified by cDNA microarrays were confirmed by Northern and protein analyses. Together, we have identified approximately 200 cDNA clones whose expression levels changed after activation and suggest that the level of expression of up-regulated genes is a molecular mechanism that differentiates the response of memory from naive CD4+ T cells.

Actins↗

PubMed2001

The potential mechanism of the diabetogenic action of streptozotocin: inhibition of pancreatic beta-cell O-GlcNAc-selective N-acetyl-beta-D-glucosaminidase.

Streptozotocin (STZ), an analogue of GlcNAc, inhibits purified rat spleen O-GlcNAc-selective N-acetyl-beta-D-glucosaminidase (O-GlcNAcase), the enzyme that removes O-GlcNAc from protein. We have shown previously that STZ increases pancreatic islet O-linked protein glycosylation. In light of these data, we investigated the possibility further that STZ causes beta-cell death by inhibiting O-GlcNAcase. In isolated islets, the time course and dose curve of STZ-induced O-glycosylation correlated with beta-cell toxicity. STZ inhibition of rat islet O-GlcNAcase activity also paralleled that of its beta-cell toxicity, with significant inhibition occurring at a concentration of 1 mM. In contrast, STZ inhibition of rat brain O-GlcNAcase and beta-TC3 insulinoma cell O-GlcNAcase was significantly right-shifted compared with islets, with STZ only significantly inhibiting activity at a concentration of 5 mM, the same concentration required for beta-TC3 cell toxicity. In comparison, N-methyl-N-nitrosourea, the nitric oxide-donating portion of STZ, did not cause increased islet O-glycosylation, beta-cell toxicity or inhibition of beta-cell O-GlcNAcase. Enhanced STZ sensitivity of islet O-GlcNAcase compared with O-GlcNAcase from other tissues or an insulinoma cell line suggests why actual islet beta-cells are particularly sensitive to STZ. Confirming this idea, STZ-induced islet beta-cell toxicity was completely blocked by GlcNAc, which also prevented STZ-induced O-GlcNAcase inhibition, but was not even partially blocked by glucose, glucosamine or GalNAc. Together, these data demonstrate that STZ's inhibition of beta-cell O-GlcNAcase is the mechanism that accounts for its diabetogenic toxicity.

Acetylglucosamine↗