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Biomedical subjects

G Sun

Publications and source records attributed to G Sun.

At least 55 records · Page 3Linked to original sources
PubMed2001

Development of aflatoxin B(1)-lysine adduct monoclonal antibody for human exposure studies.

Mouse monoclonal antibodies were developed against a synthetic aflatoxin B(1) (AFB)-lysine-cationized bovine serum albumin conjugate. The isotype of one of these antibodies, IIA4B3, has been classified as immunoglobulin G1(lambda). The affinity and specificity of IIA4B3 were further characterized by a competitive radioimmunoassay. The affinities of IIA4B3 for AFB and its associated adducts and metabolites are ranked as follows: AFB-lysine > 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl formamido)-9-hydroxy-AFB > AFB = 8,9-dihydro-8-(N(7)-guanyl)-9-hydroxy-AFB > aflatoxin M(1) > aflatoxin Q(1). IIA4B3 had about a 10-fold higher affinity for binding to AFB-lysine adduct than to AFB when (3)H-AFB-lysine was used as the tracer. The concentration for 50% inhibition for AFB-lysine was 0.610 pmol; that for AFB was 6.85 pmol. IIA4B3 had affinities at least sevenfold and twofold higher than those of 2B11, a previously developed antibody against parent AFB, for the major aflatoxin-DNA adducts 8,9-dihydro-8-(N(7)-guanyl)-9-hydroxy-AFB and 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl formamido)-9-hydroxy-AFB, respectively. An analytical method based on a competitive radioimmunoassay with IIA4B3 and (3)H-AFB-lysine was validated with a limit of detection of 10 fmol of AFB-lysine adduct. The method has been applied to the measurement of AFB-albumin adduct levels in human serum samples collected from the residents of areas at high risk for liver cancer.

Aflatoxin B1↗
PubMed2001

CD8(+)-T-cell depletion ameliorates circulatory shock in Plasmodium berghei-infected mice.

The Plasmodium berghei-infected mouse model is a well-recognized model for human cerebral malaria. Mice infected with P. berghei exhibit (i) metabolic acidosis (pH < 7.3) associated with elevated plasma lactate concentrations, (ii) significant (P < 0.05) vascular leakage in their lungs, hearts, kidneys, and brains, (ii) significantly (P < 0.05) higher cell and serum glutamate concentrations, and (iv) significantly (P < 0.05) lower mean arterial blood pressures. Because these complications are similar to those of septic shock, the simplest interpretation of these findings is that the mice develop shock brought on by the P. berghei infection. To determine whether the immune system and specifically CD8(+) T cells mediate the key features of shock during P. berghei malaria, we depleted CD8(+) T cells by monoclonal antibody (mAb) treatment and assessed the complications of malarial shock. P. berghei-infected mice depleted of CD8(+) T cells by mAb treatment had significantly reduced vascular leakage in their hearts, brains, lungs, and kidneys compared with infected controls treated with rat immunoglobulin G. CD8-depleted mice were significantly (P < 0.05) protected from lactic acidosis, glutamate buildup, and diminished HCO(3)(-) levels. Although the blood pressure decreased in anti-CD8 mAb-treated mice infected with P. berghei, the cardiac output, as assessed by echocardiography, was similar to that of uninfected control mice. Collectively, our results indicate that (i) pathogenesis similar to septic shock occurs during experimental P. berghei malaria, (ii) respiratory distress with lactic acidosis occurs during P. berghei malaria, and (iii) most components of circulatory shock are ameliorated by depletion of CD8(+) T cells.

Acidosis, Lactic↗
PubMed2001

Transduction of cellular sequence by a human immunodeficiency virus type 1-derived vector.

During studies examining the rate of human immunodeficiency virus type 1 (HIV-1) mutation in a single cycle of replication, the 5' long terminal repeat of one progeny provirus was found to contain an insertion of 147 bp including an entire tRNA sequence as well as an additional 66 bp insertion of nonviral origin. Database searches revealed that 65 of 66 bp aligned with the human CpG island sequence found on chromosomes 6, 14, and 17. Therefore it seems probable that it is of human cellular sequence origin and was transduced by HIV-1. This is the first demonstration that HIV-1 can capture a cellular sequence. The site of integration of the parental provirus was mapped to chromosome 1p32.1. Sequence with homology to the transduced CpG island was not found on chromosome 1, suggesting that the transduced cellular sequence was not linked to the site of viral integration.

Base Sequence↗
PubMed2001

Oxidative interactions of synthetic lung epithelial lining fluid with metal-containing particulate matter.

Epidemiology studies show association of morbidity and mortality with exposure to ambient air particulate matter (PM). Metals present in PM may catalyze oxidation of important lipids and proteins present in the lining of the respiratory tract. The present study investigated the PM-induced oxidation of human bronchoalveolar lavage (BAL) fluid (BALF) and synthetic lung epithelial lining fluid (sELF) through the measurement of oxygen incorporation and antioxidant depletion assays. Residual oil fly ash (ROFA), an emission source PM that contains approximately 10% by weight of soluble transition metals, was added (0-200 microg/ml) to BALF or sELF and exposed to 20% (18)O(2) (24 degrees C, 4 h). Oxygen incorporation was quantified as excess (18)O in the dried samples after incubation. BALF and diluted sELF yielded similar results. Oxygen incorporation was increased by ROFA addition and was enhanced by ascorbic acid (AA) and mixtures of AA and glutathione (GSH). AA depletion, but not depletion of GSH or uric acid, occurred in parallel with oxygen incorporation. AA became inhibitory to oxygen incorporation when it was present in high enough concentrations that it was not depleted by ROFA. Physiological and higher concentrations of catalase, superoxide dismutase, and glutathione peroxidase had no effect on oxygen incorporation. Both protein and lipid were found to be targets for oxygen incorporation; however, lipid appeared to be necessary for protein oxygen incorporation to occur. Based on these findings, we predict that ROFA would initiate significant oxidation of lung lining fluids after in vivo exposure and that AA, GSH, and lipid concentrations of these fluids are important determinants of this oxidation.

Antioxidants↗
PubMed2001

Genomic scan for exercise blood pressure in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) Family Study.

Agenome-wide linkage scan was performed for genes affecting submaximal exercise systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the sedentary state and their responses to a standardized endurance training program. A total of 344 polymorphic markers were used, and 344 pairs of siblings from 99 white nuclear families and 102 sibling pairs from 105 black family units were available for the study. All subjects were healthy but sedentary at baseline. SBP and DBP were measured during exercise tests at 2 different intensities: 50 W (SBP50 and DBP50) and 80% of maximal oxygen consumption (SBP80 and DBP80). Baseline blood pressure phenotypes were adjusted for age, gender, and body mass index, and the training responses (after training minus baseline [Delta]) were adjusted for age, gender, baseline body mass index, and baseline blood pressure. Two analytical strategies were used: a multipoint variance-components linkage analysis using all the family data and a single-point linkage analysis using pairs of siblings. In whites, promising linkages (lod score >1.75) were detected for baseline SBP80 on 10q23-q24 and for DeltaSBP50 on 8q21. In addition, several chromosomal regions with suggestive evidence of linkage (lod score 1.0 to 1.75) were observed for SBP50 (22q11.2-q13), DBP50 (6q23-q27), SBP80 (2p24, 2q21, 14q11.1-q12, and 16q21), DBP80 (6q13-q21), DeltaSBP50 (7p12-p13), and DeltaDBP50 (5q31-q32). In blacks, DBP50, DBP80, and DeltaDBP80 showed promising quantitative trait loci on 18p11.2, 11q13-q21, and 10q21-q23, respectively. Suggestive linkages were evident for DBP50 on 2p22-p25, 11p15.5, and 18q21.1; for SBP80 on 6q21-q21, 6q31-q36, 12q12-q13, 15q12-q13, and 17q11-q12; and for DBP80 on 8q24, 10q21-q24, and 12p13. All the detected chromosomal regions include several potential candidate genes and therefore warrant further studies in the Health, Risk Factors, Exercise Training and Genetics (HERITAGE) cohort and other studies.

Blood Pressure↗
PubMed2001

The predominant cholecystokinin in human plasma and intestine is cholecystokinin-33.

Cholecystokinin (CCK) occurs in multiple molecular forms; the major ones are CCK-58, -33, -22, and -8. Their relative abundance in human plasma and intestine, however, is debated. To settle the issue, extracts of intestinal biopsies and plasma from 10 human subjects have been examined by chromatography, enzyme cleavages, and measurements using a library of sequence-specific RIAs. Plasma samples were drawn in the fasting state and at intervals after a meal. The abundance of the larger forms varied with the 8 C-terminal assays in the library, as 2 assays overestimated and 3 underestimated the amounts present. One assay, however, measured carboxyamidated and O:-sulfated CCKs with equimolar potency before and after tryptic cleavage. This assay showed that the predominant plasma form is CCK-33, both in the fasting state ( approximately 51%) and postprandially ( approximately 57%), whereas CCK-22 is the second most abundant ( approximately 34% and 30%, respectively). In contrast, CCK-58 is less abundant in human intestines ( approximately 18%) and plasma ( approximately 11%). Its predominance in feline intestines, however, was confirmed. Hence, the results show a significant species variation and emphasize the necessity of highly specific and well characterized assays in molecular studies of CCK.

Animals↗
PubMed2001

Genomic diversity at thirteen short tandem repeat loci in a substructured caste population, Golla, of southern Andhra Pradesh, India.

Genomic diversity based on 13 short tandem repeat (STR) loci was studied in seven population groups of a substructured Golla caste from Chittoor district in southern Andhra Pradesh, India. These groups are traditionally pastoral, culturally homogeneous, and strictly endogamous. Blood samples were drawn from 317 individuals from 30 Golla villages. The 13 STR loci analyzed in five standard multiplex polymerase chain reactions were: (1) CSF1R, TH01, and PLA2A; (2) F13A1, CYP19, and LPL; (3) D21S1446 and D21S1435; (4) D20S481, D20S473, and D20S604; and (5) D5S1453 and D6S1006. The average heterozygosity was found to be low among the Golla subgroups (0.64-0.70) in comparison to that of groups at the upper levels of the hierarchy. The coefficient of gene differentiation was found to be moderate (average GST = 0.031; range between 0.018 and 0.049 among the loci) when compared to that observed for a similar class of markers among populations with relatively higher levels of hierarchy, for example, among castes. It is, however, much higher when compared to the average observed for Indian caste and tribal populations, based on classical markers. Genetic distance measures revealed clusters of populations that are consistent with the known ethnohistorical and geographical backgrounds of the groups. We claim that these hypervariable markers are quite useful in understanding the process of substructuring within the Indian castes, leading to the formation of smaller breeding isolates, the basic Mendelian units within which microevolutionary forces operate.

Consanguinity↗
PubMed2001

Hepatocellular carcinoma and aflatoxin exposure in Zhuqing Village, Fusui County, People's Republic of China.

Hepatocellular carcinoma (HCC) is a common cause of cancer morbidity and mortality in Asia and Africa. Epidemiological studies have found that dietary exposure to aflatoxin B1 (AFB1) and chronic infection with hepatitis B virus are two major risk factors for HCC. We have collated the incidence and mortality data of malignant tumors from 1973 to 1999 in Zhuqing Village, Fusui County, an area with very high HCC rates, and found that this cancer accounted for 64% of the total cancer incidence. Dietary intake of AFB1 was monitored for 1 week in a study group consisting of 15 males and 14 females from different households in this village. Four of 29 participants (13.8%) and 3 of 15 (20%) male participants were hepatitis B virus surface antigen positive. AFB1 was detectable in 76.7% (23 of 30) of ground corn samples (range, 0.4-128.1 ppb), 66.7% (20 of 30) of cooking peanut oil samples (range, 0.1-52.5 ppb), and 23.3% (7 of 30) of rice samples (range, 0.3-2.0 ppb) collected from each household. Mean levels of serum AFB1-albumin adducts in this group were 1.24 +/- 0.31 pmol/mg of albumin at the beginning of the study and 1.21 +/- 0.19 pmol/mg of albumin at the end of the period. Urinary AFB1 metabolites were detectable in 88.9% (24 of 27) samples (range, 0.9-3569.7 ng/24-h urine). These data provide the exposure and disease risk information for establishing intervention studies to diminish the impact of aflatoxin exposure in this high-risk population.

Adult↗
PubMed2001

[Measurement of chlorodifluoromethane(HCFC-22) in the atmosphere by using an O2-induced electron capture detector (ECD)].

Chlorodifluoromethane (CHClF2, HCFC-22), a typical substitute of dichlorodifluoromethane(CF2Cl2, CFC-12), which atmospheric concentration was only at 10(-12) V/V level. After preconcentrated air sample, O2-Induced method was used to enhance sensitivity of ECD response to HCFC-22. When O2 concentration in carrier gas was 0.54%, there was the greatest value of S/N(signal to noise) and ECD response increased by about 500 times. With the study of other conditions, such as selection of the ECD temperature, programing of the column oven temperature and carrier gas flow, a practicable analysis method with high sensitivity of ECD was established.

Air↗
PubMed2001

[Community characteristics of benthonic animals and its relationship to environmental factors in the Nanhu Lake, Changchun].

There are only 21 species of benthonic animals in the Nanhu Lake, Changchun. The dominant species in the benthos community are obvious, and the individual quantity of Limnodrilus hoffmeisteri, Branchiura sowerbyi, and Tendipus plumosus accounts for 87% of the total individual quantity of all benthonic animals. It indicates that the water in the Nanhu Lake is suffering serious organic pollution, and belongs to an eutrophic lake. The peak values of benthos biomass and energy are found in July(48.23 g WW.m-2 and 241.16 kJ.m-2 respectively), while the maximum individual quantity is appeared in May(401 ind.m-2). The distribution of Oligochaeta and aquatic insects has a significant positive correlation to organic content in the sediment(alpha < 0.05). The community structure of benthonic animals reflects adequately the feature of the Nanhu Lake as an eutrophic lake in temperate zone.

Animals↗
PubMed2001

[Ecological engineering for eutrophication control in lake].

An ecological engineering was conducted for eutrophication control in the Nanhu Lake of Changchun. In 1996, the removal of phosphorus by harvesting aquatic macrophytes and fishes was 149.6 kg and 189.9 kg, respectively, and the phosphorus fixed in molluscs was 153.4 kg. The total output was 492.9 kg, which amounted approximately to the annual phosphorus input to the lake. After ecological engineering, the water quality turned better, the TP concentration in lake water decreased, the phytoplankton density reduced, and the number of phytoplankton species increased. The roles of molluscs and fish in controlling lake eutrophication should be further studied. Ecological engineering is an ideal method to control the eutrophication of urban lakes.

Animals↗
PubMed2001

[Influence of elevated atmospheric CO2 concentration on photosynthesis and leaf nitrogen partition in process of photosynthetic carbon cycle in Musa paradisiaca].

The photosynthetic rate (Pn) in leaves of Musa paradisiaca grown under elevated CO2 concentration (700 +/- 56 microliters.L-1) for one week was 5.14 +/- 0.32 mumol.m-2.s-1, 22.1% higher than that under ambient CO2 concentration, while under elevated CO2 concentration for 8 week, the Pn decreased by 18.1%. It can be inferred that the photosynthetic acclimation to elevated CO2 concentration and the Pn inhibition occurred in leaves of M. paradisiaca. The respiration rate in light (Rd) was lower in leaves under higher CO2 concentration, compared with that under ambient CO2 concentration. If the respiration in light was not included, the difference in CO2 compensation point for the leaves of both plants was not significant. Under higher CO2 concentration for 8 weeks, the maximum carboxylation rate(Vcmax) and electron transportation rate (J) in leaves decreased respectively by 30.5% and 14.8%, compared with that under ambient CO2 concentration. The calculated apparent quantum yield (alpha) in leaves under elevated CO2 concentration according to the initial slope of Pn/PAR was reduced to 0.014 +/- 0.010 molCO2.mol-1 quanta, compared with the value of 0.025 +/- 0.005 molCO2.mol-1 quanta in the control. The efficiency of light energy conversion also decreased from 0.203 to 0.136 electrons.quanta-1 in plants under elevated CO2 concentration. A lower partitioning coefficient for leaf nitrogen in Rubisco, bioenergetics and thylakoid light-harvesting components was observed in plants under higher CO2 concentration. The results indicated that the multi-process of photosynthesis was suppressed significantly by a long-term (8 weeks) higher CO2 concentration incubation.

Carbon Dioxide↗
PubMed2001

Clinicopathologic study of mucosa-associated lymphoid tissue lymphoma of the salivary gland.

OBJECTIVE: To study the histopathologic features and pathogenesis of mucosa-associated lymphoid tissue lymphoma (MALT-oma) of salivary glands. METHODS: Clinical data, paraffin-embedded sections, immunohistochemical slides (SP method) and electron microscopic features of surgical specimens of 32 cases of salivary gland MALT-oma were studied. RESULTS: The patients were 27 males and 5 females, with a mean age of 54.76 years. The lesions were located in the parotid area in 17 cases, and in the submandibular gland in the remaining 15 cases. Much of the MALT-oma was replaced by infiltration of a great amount of centrocyte-like cells (CCL) as background and occasional large cells (centroblast- or immunoblast-like). In MALT-omas "lymphoepithelial lesions" were present. Immunohistochemically, CD20 expression was found to be positive and CD45RO expression was negative in all MALT-omas. CONCLUSION: Most of the MALT-omas are low grade malignant tumors and have a "homing back" phenomenon. The cases were managed by surgery and chemotherapy. In a few MALT-omas which turned into high grade malignant tumors, the prognosis was poor. Acquired MALT may develop as a reaction to autoimmune disease and infection. Hyper-immune reaction and MALT hyperplasia under stimulation may result in myoepithelial sialadenitis and lead to MALT-oma of the salivary gland.

Adolescent↗
PubMed2001

Monitoring of antegrade selective cerebral perfusion for aortic arch surgery with transcranial Doppler ultrasonography and near-infrared spectroscopy.

OBJECTIVE: To evaluate the safety and efficacy of antegrade selective cerebral perfusion (ASCP) during aortic arch surgery as a means of extending the safe period of systemic circulatory arrest using multimodality neuromonitoring to objectively quantify the physiologic responses. METHODS: In twenty-two patients (all less than age 60) scheduled for repair of an aortic arch aneurysm, preoperative verification of effective collateral perfusion through both the carotid and vertebrobasilar arterial systems was documented with transcranial Doppler ultrasonography (TCD). During cardiopulmonary bypass, the sole arterial inflow from the pump was via the right subclavian artery. The magnitude of ASCP was quantified by TCD using peak middle cerebral artery velocity, while flow adequacy was measured by continuous regional cerebrovenous oxygen saturation (rSO2) using dual-wavelength spatially resolved near-infrared spectroscopy. RESULTS: All patients experienced an uneventful recovery. Flow in the middle cerebral artery became undetectable at ASCP < 5 ml.kg-1.min-1, so adjustments from a 15-20 ml.kg-1.min-1 baseline were used to maintain rSO2 above 50%. Furthermore, ASCP flow was highly correlated (P < 0.01) with both peak middle cerebral artery velocity and rSO2(r = 0.86 and 0.96, respectively). CONCLUSION: Neuromonitoring guided ASCP may be expected to extend the safe period and is at least partly responsible for the absence of neurologic complications in this patient cohort.

Adolescent↗
PubMed2001

Serum granulocyte colony-stimulating factor in patients with chronic renal failure.

OBJECTIVE: To gain a better understanding of the regulatory mechanism and kinetic behaviour of granulocyte colony-stimulating factor (G-CSF). METHODS: An enzyme-linked immunosorbent assay (ELISA) method was used to detect serum G-CSF in 61 patients with chronic renal failure +/- long-term hemodialysis and 30 normal controls. RESULTS: Serum G-CSF levels in CRF patients were significantly higher than in normal controls. Eighty percent of patients had detectable G-CSF and serum G-CSF levels were 566.40 +/- 207.98 ng/L in non-hemodialyzed (non-HD) patients. The detectable percentage in hemodialyzed patients was 93.33%, serum G-CSF levels in pre-HD and post-HD patients were 1255.36 +/- 611.25 ng/L and 1151.61 +/- 599.47 ng/L respectively. Serum G-CSF levels in HD patients were slightly higher than in non-HD patients, but no significant difference was found between the two groups. No difference was found between the G-CSF values obtained in pre-HD and post-HD patients. There was no relationship between G-CSF levels and WBC, BUN or Scr (P > 0.05). CONCLUSION: The high value of G-CSF in patients with CRF may be caused by a decrease in G-CSF clearance and/or an increase in G-CSF release.

Adolescent↗
PubMed2001

[The prognostic research of expression and relationship between Helicobacter pylori of c-met oncogene correlation with gastric mucosal proliferation].

OBJECTIVE: To determine whether there is a relationship between Helicobacter pylori (Hp) and expression of c-met oncogene and proliferating cell nuclear antigen (PCNA) in gastric mucosal lesions, and prognostic significance of gastric carcinomas(GC). METHODS: Expression of c-met and PCNA were investigated in 145 gastric mucosal lesions by using immunohistochemistry. Hp was examined by Warthin-Starry method. RESULTS: For chronic superficial gastritis (CSG), chronic atrophic gastritis and intestinal metaplasia (CAS + IM), dysplasia(DYS), early GC and advanced GC, the positive rates of c-met and PCNA were higher in IM, DYS and GC than in CSG (P < 0.05). Expressions of c-met and PCNA increased with the increasing proliferation of gastric mucosa, in rank correlation test, they had a close relationship (P < 0.01). Expressions of c-met and PCNA were correlated significantly with histologic type, serosal invasion and lymph node metastasis. In particular, the expression of c-met and PCNA were significantly higher in Borrmann type 4 GC, type 3 GC and type 1, 2 than in early GC(P < 0.05). By rank correlation test, c-met and PCNA have a close relationship (P < 0.001). Expressions of c-met of Hp positive were higher than Hp negative in intestinal GC (P < 0.05). Expressions of c-met were correlated significantly with Hp positive in CAG + IM, DYS and GC. The survival rate of patients with Hp infection was significantly poorer than that of patients with Hp non-infection. CONCLUSIONS: The expression of c-met may be is associated with proliferation and malignant transformation of gastric mucosa. These results suggest that expression of c-met may be a new prognostic factor in gastric carcinoma. Hp infection and expression of c-met may be associated with in proliferation and malignant transformation of gastric mucosa. Hp infection is associated with prognosis of gastric carcinoma.

Cell Proliferation↗