PubMed Health⌕ Search

Biomedical subjects

S L Gong

Publications and source records attributed to S L Gong.

8 recordsLinked to original sources
PubMed2005

Trends of heavy metal components in the Arctic aerosols and their relationship to the emissions in the Northern Hemisphere.

Twenty-one years of observations (1980-2000) of weekly mean concentrations of major anthropogenic and natural metals in the aerosol of the lower Arctic troposphere at Alert have been analyzed by time series analysis for seasonal and long-term trends and by positive matrix factorization for major aerosol components with which metals are associated. Metals at Alert exhibit distinct seasonal variations depending on the source and origin of the metals. Anthropogenic metals such as Pb, Zn and Cu and the sea-salt components Na and Mg exhibit maxima in winter and minima in summer. Similar variations were observed for non-soil fractions of V and Mn. Weak seasonal variations were found for soil-related metals such as Al, Ba, Ca and Fe. If any trend is evident in anthropogenic metals, it is a slight decrease from 1980 to mid-1990s but generally the variation is not monotonic. It is found through the winter observations of Pb, Zn, Ni and Cu concentrations that the decline trends have been leveled off and started to increase again around 1995. No long-term trends were detected in Na, Mg and Ca concentrations but a slight decrease is observed for soil components Al, Fe and Ti after 1995. Analysis showed that these trends are mostly associated with the anthropogenic emission variations surrounding the Arctic regions.

Journal Article↗
PubMed2001

Effects of low dose radiation on signal transduction of neurons in mouse hypothalamus.

OBJECTIVE: Effects of low dose radiation on signal transduction of neurons in mouse hypothalamus were investigated. METHODS: In the present study competitive protein binding assay, radioimmunoassay, in situ hybridization and immunohistochemistry were used to observe the effects of whole-body irradiation with 75 mGy X-rays on the contents of cAMP and cGMP and the expressions of c-fos mRNA, Fos protein and proopiomelanocortin (POMC) mRNA in the neurons of mouse hypothalamus. RESULTS: The results showed that cAMP content in mouse hypothalamus immediately increased significantly and reached the peak value in 15 min after irradiation, and then returned to near sham-irradiation level 1 h after irradiation, followed by a small fluctuation of increase and decrease; the changes of cGMP content were basically opposite to those of cAMP content, while the changes of cAMP/cGMP ratio were basically consistent with those of cAMP content. The expression of c-fos mRNA in the neurons of hypothalamus appeared 15 min after irradiation, reached its peak value within 1 h, began to abate 2 h with its total disappearance 8 h after irradiation; the expression of Fos protein reached its peak value 8 h after irradiation, and then gradually returned to sham-irradiation level 48 h after irradiation; the expression of POMC mRNA decreased significantly 1 h after irradiation and remained at a lower level in the observation period of 12 h. CONCLUSION: These findings implicate that low dose radiation may potentiate the activity of the neurons in mouse hypothalamus, expedite their signal transduction, and down-regulate the functions of hypothalamus-pituitary-adrenocortical axis.

Animals↗
PubMed2000

Adaptive response of thymocyte apoptosis and cell cycle progression induced by low dose X-ray irradiation in mice.

The dose-effect of adaptive response of thymocyte apoptosis and cell cycle progression induced by whole-body X-ray irradiation (WBI) was studied in male Kunming mice. The inductive doses (D1) were 25, 50, 75, 100 or 200 mGy 6 h before the challenging doses (D2) of 1.0, 1.5 or 2.0 Gy. The changes in the percentages of the thymocyte apoptotic bodies (TAB) and the cells in different phases of cell cycle were measured with flow cytometry. The percentages of TAB decreased, the arrests of G1 and G2 + M phases diminished, and the cells of DNA synthesis of S phase increased when the D1 + D2 groups was compared with the D2 groups. When D1 was 200 mGy, the adaptive response of thymocyte apoptosis and cell cycle progression were no longer induced by low dose radiation (LDR). In addition, the extracellular fluid from the splenocytes were cultured with Con A for 48 h in vitro 24 h after 75 mGy WBI was placed in the murine thymocyte suspension from mice irradiated with 2.0 Gy WBI and co-incubated. The thymocyte apoptosis decreased. Especially, noteworthy was that the percentages of TAB after the incubation for 72 h were significantly lower than those in 2.0 Gy irradiated thymocytes (P < 0.05). These results indicate that when the mice were irradiated with 25-100 mGy (D1, 12.5 mGy/min) 6 h before 1.0-2.0 Gy (D2, 0.287 Gy/min) exposure, an adaptive response of thymocyte apoptosis and cell cycle progression may be induced under the condition of WBI, and LDR (75 mGy) may change the microenvironment of immune cells and decrease the thymocyte apoptosis.

Animals↗
PubMed1996

A nuclear mass spectrometer for studying radon progeny clusters.

A Nuclear Mass Spectrometer (NMS) system was developed and used to investigate the cluster formation of radon progeny (218Po) in gaseous H2O and H2O-SO2 environments. This NMS combines the mass-separation ability of a mass spectrometer and the low detection limit of a surface barrier detector for alpha particles and enables the detection of individual radon progeny cluster ions of defined mass at the molecular level. Clusters in the form of 218Po+(H2O)n were experimentally observed for 218Po at a relative humidity of 0.1%. The number n ranged from 1 to 7 with 4 being the most abundant peak under these conditions. No charged cluster of 218Po was detected when the relative humidity was 90%, possibly due to a neutralization process. On addition of SO2 at a low relative humidity, 218Po+(H2O)n (H2SO4)m clusters were experimentally detected for the first time by the NMS system in this study with n from 0-4 and m from 0-3. The maximum distribution occurs at a radius of about 3.65 angstrom or a mobility of about 2.00 cm2 V-1 s-1. These maximum clusters correspond to a composition of 218Po+(H2SO4)2 or 218Po+(H20)2 (H2SO4)1.

Mass Spectrometry↗
PubMed1995

Harmful effects of MSG on function of hypothalamus-pituitary-target gland system.

It has been demonstrated that neonatal administration of monosodium glutamate (MSG) results in a clearly defined lesion of the arcuate nucleus (AN) of the hypothalamus. The present study shows that fat was accumulated in the abdomen of male rats treated with MSG; weights of the body, pituitary and testis were lower; beta-EP content in hypothalamus decreased while L.EnK content increased; serum LH, FSH, TSH, GH and TS levels all decreased in varying degrees while serum PRL level significantly increased. The cAMP content lowered in pituitary, but nor in testes; clear histological changes occurred in testicular tissue; Se-GSH-Px activity in both testis and adrenal gland lowered while LPO level significantly increased. Both Se-GSH-Px activity and LPO level in liver increased. These results indicate that MSG is harmful to the function of the hypothalamus-pituitary-target system of neonatal rats.

Adrenal Glands↗
PubMed1993

[Protective effect of panaxatriols on function of reproductive endocrine axis in radiation-injured rats].

After whole body irradiation with X-ray 5 Gy (radiation condition: 0.31 Gy.min-1, 200 kV, 10 mA, 0.5 mm Cu and 1.0 mm Al), the male rats were given ip panaxatriols 5 mg.d-1 24 h before and after irradiation for 14 d. The results showed that hypothalamic leu-enkephalin (165 +/- 12 vs 131 +/- 14 pg.mg-1), pituitary beta-endorphin (2.3 +/- 0.5 vs 1.6 +/- 0.3 ng.mg-1) contents, and serum testosterone (1.66 +/- 0.15 vs 0.82 +/- 0.23 ng.ml-1) level were decreased, while serum FSH (1.34 +/- 0.10 vs 1.99 +/- 0.10 ng.ml-1) level increased in irradiation group vs normal control. These indices approached to control levels in irradiation + panaxatriols group. These suggest that panaxatriols have protective effects on reproductive endocrine axis and promote their recovering course from the radiation injuries.

Animals↗