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Biomedical subjects

Q He

Publications and source records attributed to Q He.

At least 91 records · Page 5Linked to original sources
PubMed2000

[The negative effect of 4-methylhistamine, an H2 receptor agonist, on cytotoxicity of Ara-C for HL-60 leukemia cells].

OBJECTIVE: To study the effect of 4-methylhistamine on cytotoxicity of Ara-C for HL-60 leukemia cells in vitro. METHODS: Proliferation of HL-60 cells was determined by semi-solid colony culture and 3H-TdR incorporation. The typical NBT reduction was used to check cell differentiation. Intracellular cAMP and calcium concentration were determined by high pressure liquid chromatography(HPLC) and fluorescence method, respectively. RESULTS: When HL-60 cells were pretreated with 10(-8) mol.L-1 4-MH for 24 hrs, the cytotoxicity of Ara-C[10(-8)-10(-4)mol.L-1] for HL-60 leukemia cells was significantly decreased both in liquid and semisolid culture. The result of colony counting indicated that the IC50 for HL-60 cells were 1.68 x 10(-6)mol.L-1 with 4-MH pretreatment nad 2.14 x 10(-8)mol.L-1 without 4-MH pretreatment, respectively. Therefore, the potency of Ara-C was reduced nearly 80 times according to IC50 doses. It is interesting that 10(-6)mol.L-1 ranitidine, an antagonist of H2 receptor, can elaborate the negative effect of 4-MH on cytotoxicity of Ara-C for HL-60 cells. CONCLUSION: The dose of Ara-C should be adequately increased, or Ara-C should be used with H2 receptor antagonist such as ranitidine when treating myeloid leukemia patients.

Antimetabolites, Antineoplastic↗
PubMed2000

[Effect of a novel aminosteroid on animal model of murine myelomonocytic leukemia].

To evaluate the effect of a novel aminosteroid on murine myelomonocytic leukemia, BALB/c mice were treated by the novel aminosteroid for 7 days after receiving 1 x 10(6) WEHI-3B(myelomonocytic leukemia) cells intraperitoneally. The counts and classification of white blood cells obtained from tail blood were determined on the day before transplanting WEHI-3B cells and 7, 14, 21, 28 days after transplantation. Undifferentiated cell percentage of bone marrow and spleen weight were checked 30 days after transplantation. The results demonstrated that the above indexes of mice treated with the novel aminosteroid were decreased compared with those treated with normal saline(NS). Decrease of the indexes showed a dose-dependent relationship ranging from 5-20 mg.kg-1.d-1. It is suggested that leukemia mice could be effectively treated by the novel aminosteroid and the efficacy maybe paralleled with the dosage of the novel aminosteroid.

Animals↗
PubMed2000

Hypertension, cardiovascular disease, and age-related macular degeneration. Age-Related Macular Degeneration Risk Factors Study Group.

OBJECTIVES: To describe a case-control study of risk factors for neovascular and non-neovascular age-related macular degeneration (AMD) and to present findings on associations with systemic hypertension and cardiovascular disease. METHODS: Participants with and without neovascular and non-neovascular AMD were recruited from 11 ophthalmology practices in the New York, NY, metropolitan area. Comprehensive data collection included (1) a standardized interview, (2) blood pressure measurements, and (3) blood samples. Cases and controls were classified from fundus photograph gradings. Polychotomous logistic regression analyses were used to evaluate associations. RESULTS: Classification of 1222 sets of available photographs resulted in the inclusion of a neovascular case group (n = 182), a non-neovascular case group (n = 227), and a control group (n = 235). Neovascular AMD was positively associated with diastolic blood pressure greater than 95 mm Hg (odds ratio [OR] = 4.4), self-reported use of potent antihypertensive medication (OR = 2.1), physician-reported history of hypertension (OR = 1.8), use of antihypertensive medication (OR = 2.5), combinations of self-reported and physician-reported data on hypertension and its treatment (OR = 1. 7), high-density lipoprotein level (OR = 2.3), and dietary cholesterol level (OR = 2.2). Non-neovascular AMD was unrelated to hypertension or cholesterol level. No associations were found between either AMD type and other definitions of hypertension or other cardiovascular disease. CONCLUSIONS: These findings suggest that neovascular AMD is associated with moderate to severe hypertension, particularly among patients receiving antihypertensive treatment. They also support the hypotheses that neovascular and non-neovascular AMD may have a different pathogenesis and that neovascular AMD and hypertensive disease may have a similar underlying systemic process.

Aged↗
PubMed2000

Three-dimensional electrophoretic NMR correlation spectroscopy.

A novel method of three-dimensional electrophoretic NMR correlation spectroscopy (3D EP-COSY) has been proposed, developed, and implemented. It has a demonstrated potential of facilitating simultaneous structural assignments of multiple proteins in mixtures. The principle is to add a pulsed DC electric field that introduces a new dimension of electrophoretic flow, in which resonances of different molecules can be separated by their electrophoretic migration rates without physical separation. As a result, two COSY spectra were simultaneously obtained in a single 3D EP-COSY experiment from a mixture of 150 mM l-aspartic acid and 148 mM 4, 9-dioxa-1,12-dodecanediamine with concurrent resolution of their chemical shifts and J-coupling constants. This approach creates a new horizon of multidimensional electrophoretic NMR. The technical advance opens doors for structure characterization of complex protein systems and protein interactions, which are at the basis of biochemical mechanisms and the phenomena of living systems.

Alkanes↗
PubMed2000

Flow injection spectrophotometric determination of anionic surfactants using methyl orange as chromogenic reagent.

A flow injection(FI) spectrophotometric method for the determination of anionic surfactants was developed on the basis of the competition for the cationic surfactant cetyl pyridine (CP+) chloride between the acidic dye methyl orange (MO) and anionic surfactants. In a pH 5.0 medium the cation of cetyl pyridine (CP+) reacts with dissociated methyl orange (MO-) to form an ion-associate complex, causing a blue shift of lambda(max) from 465 nm for MO- to 358 nm for the CP+ x MO- associate. The MO- in the ion-associate complex can be quantitatively substituted by such anionic surfactants as sodium dodecyl benzene sulfonate (DBS) or sodium lauryl sulfate (LS), leading to an increase in the absorbance measured at 465 nm. This increased absorbance value is proportional to the concentration of anionic surfactants. Various chemical and physical parameters for the FI spectrophotometric method were optimized, and interference-free levels were examined. At the optimized conditions, Beer's law was obeyed in the range 1.4 approximately 25 mg/L sodium DBS for an injected sample volume of 180 microL, and a detection limit of 0.22 mg/L for sodium DBS was achieved at a sampling rate of 90 h(-1). Eleven determinations of a 16 mg/L sodium DBS solution gave a RSD of 0.4%. The proposed method has successfully been applied to the determination of anionic surfactant concentration in waste water and in detergents.

Anions↗
PubMed2000

Calibration of a field-portable gamma detector to obtain in situ measurements of the 137Cs inventories of cultivated soils and floodplain sediments.

Over the past 10 years, a number of studies have exploited the potential for using measurements of fallout 137Cs inventories to document rates and patterns of soil erosion on cultivated land and to estimate rates of overbank sedimentation on river floodplains. Traditional procedures for applying the 137Cs technique involve the collection of soil or sediment cores from a study site and their subsequent transfer to the laboratory for preparation and analysis by gamma spectrometry. Such procedures are time consuming and there may be a considerable delay before the results are available. It is therefore difficult to obtain preliminary results, which could be used to guide the development of an ongoing sampling programme. The use of in situ gamma spectrometry measurements to quantify 137Cs inventories in soils and sediments offers a number of potential advantages over traditional procedures. However, in order to derive a reliable estimate of the 137Cs inventory for a measurement point, it is necessary to take account of the attenuation of 137Cs gamma rays by the soil matrix and information on the depth distribution of 137Cs in the soil or sediment is therefore required. In the present study, empirical relationships between in situ measurements of 137Cs activity and total 137Cs inventories have been established for soils from a cultivated field and for floodplain sediments, based on information on the vertical distribution of 137Cs in the soils and sediments provided by the forward scattering ratio derived from the field measured spectra. These relationships have been used to estimate 137Cs inventories from in situ measurements of 137Cs activity at other locations.

Cesium Radioisotopes↗
PubMed2000

Stability and cooperativity of individual tertiary contacts in RNA revealed through chemical denaturation.

For proteins, understanding tertiary interactions involved in local versus global unfolding has become increasingly important for understanding the nature of the native state ensemble, the mechanisms of unfolding, and the stability of both the native and intermediate states in folding. In this work we have addressed related questions with respect to RNA structure by combining chemical denaturation and hydroxyl radical footprinting methods. We have determined unfolding isotherms for each of 26 discrete sites of protection located throughout the Tetrahymena thermophila group I ribozyme. The cooperativity of folding, m-value, and the free energy, DeltaG degrees N-U, associated with formation of each tertiary contact was determined by analysis of the isotherms. The DeltaG degrees N-U values measured in this study vary from 1.7 +/- 0.2 to 7. 6 +/- 1.2 kcal mol-1. Thus, the stability of these discrete tertiary contacts vary by almost 104. In addition, an intradomain contact and three interdomain contacts show high cooperativity (m-values of 1.1 +/- 0.2 to 1.7 +/- 0.3 kcal mol-1 M-1) indicating that these contacts exhibit global cooperatively in their folding behavior. This new approach to examining RNA stability provides an exciting comparison to our understanding of protein structure and folding mechanisms.

Allosteric Site↗
PubMed2000

Risk factors of obesity in preschool children in China: a population-based case--control study.

OBJECTIVE: To identify the risk factors of obesity in preschool children in China. DESIGN: A nationwide case-control study in eight cities in China. SUBJECTS: A total of 748 boys and 574 girls (age 0.1 - 6.9 y), including the obese and non-obese. One obese child was matched with one non-obese child by sex and age. MEASUREMENTS: Weight, height and other measurements were taken for all the subjects. The information on child activity, feeding pattern and family background was collected by our study team from the parents and the kindergarten teacher. RESULTS: Birth weight > or =4.0 kg, high eating speed, obesity among the child's relatives > or =25%, mother's body mass index (BMI) > 25 kg/m2 and father's BMI > 25 kg/m2 were identified as the major significant (P < 0.05) risk factors of obesity in preschool children in China. CONCLUSION: Family history of obesity, high birth weight and eating speed were identified as the risk factors of obesity in preschool children in China. Our results show the need for family therapy as part of an intervention program for childhood obesity, which includes behavior modification.

Birth Weight↗
PubMed2000

Calcium phosphate nanoparticle adjuvant.

Vaccination to protect against human infectious diseases may be enhanced by using adjuvants that can selectively stimulate immunoregulatory responses. In a murine model, a novel nanoparticulate adjuvant composed of calcium phosphate (CAP) was compared with the commonly used aluminum (alum) adjuvants for its ability to induce immunity to herpes simplex virus type 2 (HSV-2) and Epstein-Barr virus (EBV) infections. Results indicated that CAP was more potent as an adjuvant than alum, elicited little or no inflammation at the site of administration, induced high titers of immunoglobulin G2a (IgG2a) antibody and neutralizing antibody, and facilitated a high percentage of protection against HSV-2 infection. Additional benefits of CAP include (i) an insignificant IgE response, which is an important advantage over injection of alum compounds, and (ii) the fact that CAP is a natural constituent of the human body. Thus, CAP is very well tolerated and absorbed. These studies were performed with animal models. By virtue of the potency of this CAP adjuvant and the relative absence of side effects, we believe that this new CAP formulation has great potential for use as an adjuvant in humans.

Adjuvants, Immunologic↗
PubMed2000

Rapid differentiation of Borrelia garinii from Borrelia afzelii and Borrelia burgdorferi sensu stricto by LightCycler fluorescence melting curve analysis of a PCR product of the recA gene.

To differentiate the Borrelia burgdorferi sensu lato genospecies, LightCycler real-time PCR was used for the fluorescence (SYBR Green I) melting curve analysis of borrelial recA gene PCR products. The specific melting temperature analyzed is a function of the GC/AT ratio, length, and nucleotide sequence of the amplified product. A total of 32 DNA samples were tested. Of them three were isolated from B. burgdorferi reference strains and 16 were isolated from B. burgdorferi strains cultured from Ixodes ricinus ticks; 13 were directly isolated from nine human biopsy specimens and four I. ricinus tick midguts. The melting temperature of B. garinii was 2 degrees C lower than that of B. burgdorferi sensu stricto and B. afzelii. Melting curve analysis offers a rapid alternative for identification and detection of B. burgdorferi sensu lato genospecies.

Animals↗
PubMed2000

Isoproterenol and cAMP regulation of the human brain natriuretic peptide gene involves Src and Rac.

Brain natriuretic peptide (BNP) gene expression and chronic activation of the sympathetic nervous system are characteristics of the development of heart failure. We studied the role of the beta-adrenergic signaling pathway in regulation of the human BNP (hBNP) promoter. An hBNP promoter (-1818 to +100) coupled to a luciferase reporter gene was transferred into neonatal cardiac myocytes, and luciferase activity was measured as an index of promoter activity. Isoproterenol (ISO), forskolin, and cAMP stimulated the promoter, and the beta(2)-antagonist ICI 118,551 abrogated the effect of ISO. In contrast, the protein kinase A (PKA) inhibitor H-89 failed to block the action of cAMP and ISO. Pertussis toxin (PT), which inactivates Galpha(i), inhibited ISO- and cAMP-stimulated hBNP promoter activity. The Src tyrosine kinase inhibitor PP1 and a dominant-negative mutant of the small G protein Rac also abolished the effect of ISO and cAMP. Finally, we studied the involvement of M-CAT-like binding sites in basal and inducible regulation of the hBNP promoter. Mutation of these elements decreased basal and cAMP-induced activity. These data suggest that beta-adrenergic regulation of hBNP is PKA independent, involves a Galpha(i)-activated pathway, and targets regulatory elements in the proximal BNP promoter.

Adrenergic beta-Agonists↗
PubMed2000

Interleukin-1beta regulates the human brain natriuretic peptide promoter via Ca(2+)-dependent protein kinase pathways.

We have shown that interleukin-1beta (IL-1beta) activates the human brain natriuretic peptide (hBNP) promoter via a transcriptional mechanism. Others have reported that changes in intracellular calcium (Ca(2+)) mediate the action of IL-1beta. We questioned whether Ca(2+) and Ca(2+)-dependent pathways mediate IL-1beta regulation of the hBNP promoter in cardiac myocytes. The hBNP promoter (-1818 to +100) coupled to a luciferase cDNA reporter gene was transferred into neonatal cardiac myocytes. Cells were then treated with agents that modify Ca(2+) levels or inhibit Ca(2+)-dependent kinases, and luciferase activity was measured as an index of hBNP promoter activity. The Ca(2+) ionophore A23187 increased hBNP promoter activity; however, neither EGTA nor nifedipine reduced IL-1beta-stimulated promoter activity. Long-term treatment with thapsigargin, which depletes intracellular Ca(2+) stores, decreased basal promoter activity and blocked the effect of IL-1beta. Inhibition of protein kinase C completely blocked IL-1beta-stimulated hBNP promoter activity, whereas inhibition of Ca(2+)/calmodulin-dependent kinase II decreased promoter activity by 40%. In contrast, inhibition of the Ca(2+)-regulated phosphatase calcineurin by cyclosporin A had no effect. These data suggest that (1) Ca(2+) activates the hBNP promoter; (2) release of Ca(2+) from intracellular stores is important to IL-1beta regulation of the hBNP promoter, but transport via voltage-sensitive Ca(2+) channels is not; (3) protein kinase C and Ca(2+)/calmodulin-dependent kinase II mediate the action of IL-1beta; and (4) the phosphatase calcineurin is not involved in IL-1beta regulation of the hBNP promoter. Thus, Ca(2+) and Ca(2+)-dependent pathways are critical to IL-1beta regulation of the hBNP promoter.

Animals↗
PubMed2000

Blood pressure is associated with body mass index in both normal and obese children.

Obesity is associated with elevated blood pressure (BP) both in adults and children. Childhood obesity has become a severe health problem, especially during the last few decades. So far there has not been any large-scale study specifically focusing on the association between obesity and BP in early life. The aim of this study is to examine systematically the association between obesity and BP in preschool Chinese children in mainland China. In 1996, measurements of weight, height, and BP values were collected in a nationwide, case-control study of 748 boys and 574 girls who ranged in age from 0.1 to 6.9 years in 8 cities in mainland China. One obese child and 1 nonobese child were matched for gender and age. The BP differences of the mean-matched pair were approximately 5 mm Hg for systolic blood pressure (SBP) and approximately 4 mm Hg for diastolic blood pressure (DBP) (P<0.05); a higher value was noted in obese children. The BP value of 19.4% children in the obese group and 7.0% children in the nonobese group was higher than the 95th percentile value (P<0.0001), which is defined as high BP by the Task Force on Blood Pressure Control in Children. Both SBP and DBP were significantly (P<0.05) positively related to body mass index (BMI) values (P<0.05) for children in obese and nonobese groups after adjustment for age, gender, and height. To be specific, an increase of 1 BMI unit was associated with, on average, an increase of 0.56 mm Hg and 0.54 mm Hg in SBP and DBP, respectively, for obese children. In nonobese children, the increase in SBP and DBP was 1.22 mm Hg and 1.20 mm Hg, respectively. An increase in the BMI is conclusively associated with elevated SBP and DBP in nonobese children. Furthermore, an increase in the adjusted BMI was associated with an increase in SBP and DBP in obese and nonobese children.

Blood Pressure↗
PubMed2000

Endocrine disruptive effects of polychlorinated aromatic hydrocarbons on intestinal cholecystokinin in rats.

The ubiquitous and persistent nature of polychlorinated aromatic hydrocarbons (PCAHs) in our environment and the risk of exposure to PCAHs have provoked concern over their potential toxicity. In humans, exposure to PCAHs is aimed chiefly at epithelial cells residing in the intestinal mucosa, because oral intake of contaminated food is a major source of PCAHs. The purpose of this study, therefore, was to examine the effects of chronic exposure to various PCAHs [i.e. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), 3,3',4,4',5-pentachlorobiphenyl (PCB-126), and 2,2'4,4'5,5'-hexachlorobiphenyl (PCB-153)], given alone or as mixtures, on intestinal cholecystokinin (CCK) peptide and messenger RNA levels. We show that chronic PCAH treatment significantly lowers intestinal levels of stored CCK peptide. Intestinal CCK messenger RNA levels are not affected. In addition, 3,3',4,4',5-pentachlorobiphenyl treatment increased intestinal insulin-like growth factor-binding protein-3 levels in a dose-related manner. Acute 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment of intestinal CCK cells lowered levels of CCK-processing enzymes (i.e. prohormone convertase-1 and -2). Together, these data indicate that PCAHs may decrease intestinal levels of stored CCK peptide by affecting the intestinal insulin-like growth factor system and CCK processing.

Animals↗
PubMed2000

A genetic study of the depressive respiratory responses to hypoxia in chronic obstructive pulmonary disease patients with type II respiratory failure.

OBJECTIVE: The depression of the ventilatory and P(0.1 )responses to hypoxia and hypercapnia may play an important role in the development of CO(2) retention in the patients with chronic obstructive pulmonary disease (COPD). The purpose of this study was to investigate if there is any linkage relationship between the depressed ventilatory and P(0.1) response phenotypes and the microsatellite markers on chromosome 6q21.1-21.2 among Chinese people. METHODS: P(0.1) and ventilatory responses to hypoxia were measured in six COPD patients with type II respiratory failure, as well as in their 21 normal adult offsprings. Polymerase chain reaction (PCR), denaturing polyacrylamide gel electrophoresis and silver staining techniques were used to study the amplified fragment length polymorphism. Linkage analysis was done with the LINKAGE program. RESULTS: Hypoxia response was low in 10 offsprings, and normal in the other 11 offsprings. Linkage analysis showed the maximum Lod score was 1.74(D6S276, theta = 0.10). CONCLUSION: The depressed hypoxia response might have been influenced by genetic factors. The model was in accord with autosomal dominant inheritance. The disease-related gene was linked to D6S276 locus.

Adult↗
PubMed2000

Population-based body mass index reference values from Göteborg, sweden: birth to 18 years of age.

UNLABELLED: The body mass index or BMI (weight/height2) is a somewhat crude estimate of nutritional status. However, due to its simplicity and high correlation with total body fat, it has been the method of choice in both paediatric clinics and research over the years. Since BMI is not an equivalent measure of the percentage of body fat in different ethnic groups and in the two sexes, population-specific BMI reference data is needed. Several BMI reference values have been published for French, American, British and Hong Kong children in recent years. In Sweden, weight-for-age and height-for-age reference values, which were published in 1976, are still used as the current national growth reference values. Updated growth reference values are needed for assessing nutritional status due to the secular trend toward and increasing prevalence of childhood obesity. The aim of this study was to produce BMI reference values for Swedish children of paediatric age. The series came from a large Swedish population-based longitudinal growth study of 3650 full-term babies followed from birth to 18 y of age. The children in this data set were born in the early 1970s. The pattern and level of 50th centile BMI values presented here are quite similar to those of the Swedish cohort study in the 1950s. In comparison with the US BMI reference values, the Swedish values are much lower, especially for the higher centile values. CONCLUSION: The new Swedish BMI chart from our study may provide a useful tool for paediatricians to assess body fat, and consequently nutritional status, in Swedish children.

Adolescent↗