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Biomedical subjects

J Liu

Publications and source records attributed to J Liu.

At least 793 records · Page 44Linked to original sources
PubMed2000

Chiroptical switches and sensors based on ligand conformational changes in labile coordination complexes.

A series of molecules have been developed that give significantly differentiated circular dichroic signals upon presentation of a metal ion, exchange of metal ion, or change in oxidation state. These properties have led to prototypes of molecular sensors for metal ions and redox-mediated chiroptical switches. In some complexes, the CD signal arises by an excitonic coupling mechanism, affording further information about ligand conformation or absolute configuration.

Circular Dichroism↗
PubMed2000

[The realization methods of 3D ultrasonic blood flow mapping].

3D ultrasonic blood flow mapping has undergone significant technological refinements in image acquisition, signal processing and display techniques since its introduction in 1982. This paper describes the realization methods of 3D ultrasonic blood flow mapping systems. The performances of different systems are evaluated from the views of 3D localization, design of wall filters, velocity estimation and 3D visualization.

Blood Flow Velocity↗
PubMed2000

Distribution of substance P-like immunoreactive fibers in feline temporomandibular joint.

OBJECTIVE: To study the distribution of substance P-like immunoreactive fibers in feline temporomandibular joint. METHODS: The immunohistochemical PAP method was used for the investigation of the distribution of substance P-like immunoreactive fibers in feline temporomandibular joint. RESULTS: The TMJ capsule and the anterior and posterior disc attachments all contained SP-immunoreactive nerve fibers, but the medium fibers in diameter were mainly observed. The density of the distribution of SP-positive nerve fibers was the highest in the subsynovium of the TMJ capsule. The density of distribution was similar in the anterior and posterior disc attachments, but lower than in the subsynovium and the lateral joint capsule. Such fibers in the synovial membrane were sparser, and a part of the fibers were seen around the thin blood vessels in all the foregoing tissues. CONCLUSION: These results provide the morphological data for exploring the neurobiological mechanisms of temporomandibular joint disorder and its pain.

Animals↗
PubMed2000

Peroxynitrite leads to arteriolar smooth muscle cell membrane hyperpolarization and low vasoreactivity in severe shock.

This paper aimed to study the mechanism of vascular hyporeactivity during severe hemorrhagic shock. Rats were divided into control and shock group. Membrane potential of arteriolar strips was measured with intracellular recording method and membrane potential changes in arteriolar smooth muscle cells (ASMC) were recorded with membrane potential sensitive fluorescent dye (DiBAC4) and confocal microscopy. Hyperpolarization of ASMC membrane appeared at the late stage of shock, which correlated to low vasoreactivity. Glybenclamide, an inhibitor of K(ATP) channel reversed the hyperpolarizing effect. S-nitroso-N-acetylpenicillamine (SNAP), a donor of NO, in a higher concentration (400 mol/l) caused membrane hyperpolarization in control and shock group, which was completely reversed by application of Tiron, a scavenger of O2-. The hyperpolarizing effect of SNAP was decreased by ODQ, glybenclamide and (or) charybdotoxin. It is concluded that hyperpolarization of ASMC leads to vascular hyporeactivity. Peroxynitrite (OONO-) involves in the development of hyperpolarization in severe shock. The production of cGMP and activation of K(ATP) and K(Ca) channel contribute to the hyperpolarizing effect of OONO-*.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed2000

[The relationship between dental fluorosis and dietary pattern among Tibetan children in natural protective areas of Mount Qomolangma].

OBJECTIVE: To study the relationship between dietary pattern and dental fluorosis among Tibetan children in natural protective areas of Mount Qomolangma. METHODS: Environmental fluorine levels, dietary pattern and occurrence of dental fluorosis among children in Xieger town, Dingri County and Zhangmu town, Nielamu County, were studied. RESULTS: The total fluorine intake in children was 8.039 mg in Xieger town and the prevalence rate of dental fluorosis was 75.93%. The total fluorine intake and morbidity of dental fluorosis are 2.797 mg and 25.86% respectively in Zhangmu town. CONCLUSION: It suggested that fluorosis of children is related to total fluoride intake.

Adolescent↗
PubMed2000

Tumor necrosis factor and reactive oxygen species cooperative cytotoxicity is mediated via inhibition of NF-kappaB.

BACKGROUND: Tumor necrosis factor alpha (TNFalpha) plays a key role in pathogenesis of brain injury. However, TNFalpha exhibits no cytotoxicity in primary cultures of brain cells. This discrepancy suggests that other pathogenic stimuli that exist in the setting of brain injury precipitate TNFalpha cytotoxicity. The hypothesis was tested that reactive oxygen species (ROS), that are released early after brain injury, act synergistically with TNFalpha in causing cell death. MATERIALS AND METHODS: Cultured human and rat brain capillary endothelial cells (RBEC), and cortical astrocytes were treated with TNFalpha alone or together with different doses of H2O2, and apoptotic cell death and DNA fragmentation were measured by means of 3'-OH-terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Hoechst fluorescence assay, respectively. The effect of H2O2 on TNFalpha-induced activation of nuclear factor kappa B (NF-kappaB) was measured by Western blots of cytoplasmic and nuclear extracts of RBEC using anti-inhibitor of NF-kappaB (IkappaB) and anti-p65 subunit of NF-kappaB antibodies. Nuclear translocation of NF-kappaB was investigated by immunofluorescent staining of RBEC with anti-p65 antibodies. RESULTS: TNFalpha alone had no cytotoxic effect in brain endothelial cells and astrocytes at concentrations up to 100 ng/ml. Co-treatment with 5-10 microM of H2O2 caused a two-fold increase in the number of apoptotic cells 24 hr later. Similar doses (1-3 microM) of H2O2 initiated early DNA fragmentation. H2O2 inhibited TNFalpha-induced accumulation of p65 in the nucleus, although it had no effect on degradation of the IkappaB in cytoplasm. Immunostaining confirmed that H2O2 inhibited p65 transport to the nucleus. CONCLUSIONS: Reactive oxygen species could act synergistically with TNFalpha in causing cytotoxicity via inhibition of a cytoprotective branch of TNFalpha signaling pathways, which starts with NF-kappaB activation.

Animals↗
PubMed2000

[Effect of Sophora flavescens Ait on cultured beating myocardial cells of coxsackie B3 virus infected newborn rat].

OBJECTIVE: Coxsackie B viruses (CVB3) are considered to be the most common etiologic agents of viral myocarditis. There are not any special anti-CVB3 drugs yet. From previous studies, the anti-CVB3 affect of sophora flavescens ait (SFA) had been discovered. Our experiment was to study the anti-CVB3 ability of SFA to cultured heating myocardial cells of CVB3 infected newborn rat. METHODS: The myocardial cells were divided into four groups: 1. infected group (n = 8), infected only with CVB3, not adding SFA; 2. treated group (n =8), infected with CVB3, adding SFA (100 microg/ml); 3. drug group (n=6), adding SFA (100 microg/ml) only; 4. control group (n = 6), not infected with CVB3, not adding SFA. RESULTS: The myocardial cells of the infected group had cell pathogenic effect (CPE) on the second day after virus inoculation, the CPE progressed rapidly from + to ++++. In contrast, no CPE in the other three groups was found. The LDH and SGOT of the infected group were higher than that in the other three groups, showing a significant difference (P <0.05). The virus titer of the infected group was higher than that of the treated group. There was no influence on normal myocardial cells if the concentration of SFA was lower than 300 microg/ml. When the concentration of SFA was 6.25 microg/ml 200 microg/ml, it showed protective effect on infected myocardial cells. CONCLUSIONS: The results of the experiment suggest that SFA might inhibit CVB3 replication in myocardial cells.

Animals↗
PubMed2000

[Individual biomass of natural Pinus densiflora].

The aboveground biomass of individuals with different growth potentials in natural Pinus densiflora forest with different stand densities was measured in Yanbian, Jilin Province. The variation of individual biomass affected by densities was in order of dominant tree < intermediate tree < suppressed tree, while the distribution proportion of biomass in different organs affected by densities was: in order of trunk > branch > needle > bark. The biomass components of P. densifliora with different growth potentials varied markedly with the approaching of density class III, and the change of intermediate trees was similar to the whole stand. The vertical distributions of biomass of different trees were different from each other, but all showed that the biomass of trunks and barks was mainly distributed below 6 m high from ground, that of branches was within 6-10 m high, that of needles was uniform in the upper, middle and lower layers, and that of branches and needles in upper layer was least affected by density.

Biomass↗
PubMed2000

[Variation of dormancy characteristic of different Pinus bungeana seed sources].

Studies on the dormancy characteristics of Pinus bungeana seeds from 7 representative seed sources show that the difference of water permeability of seed capsule was very significant among seed sources. The seeds from northern part of distribution area had a much higher water permeability than from the south. According to water permeability, the seven seed sources were divided into 2 geographical groups, with Qinling Mountain as the division line. The difference of seed ventilation was caused firstly by outer seed capsule, and secondly by inner one. The variation of permeability had a similar trend with the ventilation. The inhibition ability of seed extracts was significantly different among different seed sources, which was increased with the concentration of seed extracts. Based on the inhibition ability of extracts from seed capsule and endosperm, the seven seed sources were divided into 2 and 3 geographical groups, respectively. The germination capacity decreased with increasing latitude, and seeds with poor germination capacity took relatively more time for germination. All population groups based on different division criteria showed such a character, i.e., the difference of seed characteristics was more significant among groups than in same group, and the distance of seed source was longer among groups than in a group. The difference of dormancy characteristics of different P. bungeana seed sources was the result of interaction between climatic and geographical factors.

Germination↗
PubMed2000

[Environmental fluorine level in Tibet].

The concentration of fluorine in water, soil, fuel, food, vegetable and tea in Tibetan habitats with different environmental characteristic were measured by ion-specific electrode potentiometer. The results showed that the fluorine concentration in water, soil, fuel, food vegetable, butter tea and Zanba both of them were made from brick teas was 0.06 mg.L-1, 0.45 mg.kg-1, 0.10 mg.kg-1, 0.06-0.33 mg.kg-1, 3.09 mg.L-1 and 3.61 mg.kg-1, respectively. The water-soluble fluorine content in brick tea which came from Sichuan and Yunnan Provinces reached up to 533.89-617.32 mg.kg-1. It is suggested that drinking brick tea may induce fluorosis in Tibetan habitats.

Environment↗
PubMed2000

[Nitrogen dynamics in different organs of Calamagrostis angustifolia and Carex lasiocarpa in Sanjiang plain].

The dynamics of nitrogen content and storage in different organs of Calamagrostis angustifolia and Carex lasiocarpa which are dominant vegetation in swamp wetland were determined, and the utilization rate of nitrogen and its nutrient limitation in the region were analyzed. The results showed that the aboveground and underground biomass might be described by p = gamma + alpha t + beta t2 and p = a0 + b0t, respectively. The content of total N, NH4(+)-N and NO3(-)-N varied widely with different organs because of the effects of soil water, nutrient content, atmospheric temperature, vegetable feature and selective absorption to nitrogen, etc. The content of NO3(-)-N in different organs varied less than that of NH4(+)-N, and NH4(+)-N/NO3(-)-N was < 1. The N:P content less than 14 in two vegetations showed that it was N but not P was the limitation nutrient to the growth of vegetation in this region, moreover, the limitation was less in July than in August. This conclusion was also drawn from the analysis of the NH4(+)-N and NO3(-)-N content in soil.

Biomass↗
PubMed2000

[Nitrogen content variation in litters of Deyeuxia angustifolia and Carex lasiocarpa in Sanjing plain].

This paper dealt with the litter of two dominant species Deyeuxia angustifolia and Carex lasiocarpa in swamp of Sanjiang Plain, and analyzed the seasonal variation and content feature of nitrogen in litter and its roles on maintaining matter equilibrium in ecosystems. The nitrogen content in litter decreased with the increasing temperature and above-ground biomass. The weightlessness rate of litter increased with time, and the annual accumulative weightlessness rates of D. angustifolia and C. lasiocarpa were 32.2% and 27.7%, respectively. The annual accumulative nitrogen input amount of D. angustifolia community was 1478 mg.m-2, C. lasiocarpa 587 mg.m-2, while the annual accumulative nitrogen output amount in litter of D. angustifolia community was 759 mg.m-2, C. lasiocarpa 410 mg.m-2. It was suggested that the nitrogen input amount was higher than output, and that the state of nitrogen accumulation was beneficial to the stability of the ecosystems.

Biodegradation, Environmental↗
PubMed2000

[Quantitative characteristics of rare and endangered Castanopsis kawakamii population].

In this paper, a new self-adaptive model for population growth, i.e. S = exp(alpha ln2(1 + ce-rt) + beta ln(1 + ce-rt) + gamma) was established, which combined Logistic, Smith, Gompertz, Gui-Lawson, Zhang-Logistic and Liu-Logistic models. Estimations with genetic algorithm showed that the new model was more suitable than other models to simulate the actual growth trend of Castanopsis kawakamii population.

China↗
PubMed2000

[Dynamics of soil P pool in a long-term fertilizing experiment of wheat-maize rotation. I. Crop yield effect of fertilizer P and dynamics of soil total P and inorganic P].

The effects of long-term applying fertilizer P and manure on the pools of soil total P and inorganic P and the crop yield in rotation of winter wheat-summer maize-->spring maize were studied. The results showed that the pool of soil total P and inorganic P were increased by applying fertilizer P and manure, and the phosphorus mostly accumulated in soil was inorganic P. The critical amounts of fertilizer P (P2O5) for balancing soil P were 94.7 kg.hm-2 to winter wheat-summer maize and 51.5 kg.hm-2 to spring maize. Based on regression equations, the application rates of fertilizer P (P2O5) for economic optimum and highest yields were 135.8 and 149.8 kg.hm-2 to winter wheat-summer maize, and 88.6 and 95.9 kg.hm-2 to spring maize, respectively.

China↗
PubMed2000

[Dynamics of soil P pool in a long-term fertilizing experiment of wheat-maize rotation. II. Dynamics of soil Olsen-P and inorganic P].

Studies on the dynamics of soil Olsen-P and different form inorganic P in the long-term fertilizing experiment of winter wheat-summer maize-->spring maize rotation showed that the contents of Olsen-P and inorganic P were changed by the accumulation and consumption of P in soil. In P0 treatments, Olsen-P decreased gradually, and then, trended to the critical level. When fertilizing amount was basically equal to the intake by crops, the balance of Olsen-P was dynamically maintained. The contents of Olsen-P and inorganic P were enhanced, when applied P was larger than the P intake by crops. The major contents of residual inorganic P were Ca2-P and Ca8-P, both accounting for 52.3% of total inorganic P in average, and Ca8-P accounting for 78.3%. Al-P and Fe-P accounted for 26.1%, and O-P and Ca10-P accounted for 20.4% of total inorganic P. The availability of fertilizer P was obviously increased by long-term applying fertilizer P together with manure, compared with applying fertilizer P alone.

China↗
PubMed2000

[Tree species diversity in gaps of different sizes and developmental stages in lower subtropical evergreen broadleaved forest, South China].

The change pattern of tree species diversity in gaps of different sizes and developmental stages in the lower subtropical evergreen broadleaved forest was analyzed in this paper. The species diversity index(Shannon-Wienner) did not change in the gaps with a size of < 400 m2, reached the highest in those with a size of 400-500 m2 and the lowest in the gaps of 500-600 m2 size, and increased in those with a size of > 600 m2. The index was the highest in the middle period of 20-50 years, secondly high within 20 years, and lowest after 50 years of gap formation. The species diversity in regeneration layer(H < 1.5 m) reached a peak in the gaps with a size of 500-600 m2, and the lowest values occurred at the gaps with a size of > 600 m2 and 200-300 m2. Species diversity index in the regeneration layer reached the highest in the first 10 years after gap formation, then revealed a general trend of decreasing, but two relative peaks were formed in the gap ages of about 30-40 years and 50-60 years, respectively. The general trends of species richness were correspondent with those of species diversity index. Gaps of different sizes and ages had a strong influence on the tree species regeneration through changes of ecological factors in gaps, thus, tree species diversity was different in gaps of different sizes and ages. Gap is one of the most important mechanisms for the maintenance of tree species diversity in the lower subtropical evergreen broadleaved forest.

China↗
PubMed2000

The circadian rhythm of blood pressure and the effect of salt intake in salt-sensitive subjects.

OBJECTIVE: To investigate the effect of salt intake on the circadian rhythm of blood pressure and the characteristics of ambulatory blood pressure (ABP) in salt-sensitive (SS) subjects. METHODS: Twenty-three normotensive subjects and forty-three patients with essential hypertension were included in this study. Salt sensitivity was determined with a chronic dietary salt loading test and an acute venous saline loading test, respectively. 24-hour ABP measurements were performed twice in normotensive subjects when they were on a high salt diet and when they had a low salt diet. Blood and urine samples were collected for measurement of plasma norepinephrine concentration (PNE), plasma renin activity (PRA), angiotensin II, aldosterone, erythrocyte sodium content and urinary sodium excretion. 24-hour ABP readings were also obtained in patients with essential hypertension when antihypertensive drugs were discontinued for at least 2 weeks. RESULTS: High salt intake attenuated the circadian rhythm of blood pressure in SS normotensive subjects, and the nocturnal decline in blood pressure was smaller in SS patients with essential hypertension than in salt-resistant (SR) patients. The level of PNE was higher and the suppression of PRA was smaller in SS subjects than in SR subjects when they had a high salt diet, and the urinary sodium excretion decreased and the erythrocyte sodium content increased significantly in SS subjects on high salt intake. CONCLUSIONS: High salt intake caused an abnormal circadian rhythm of blood pressure in SS subjects. The blunted nocturnal decline in blood pressure may be a characteristics of SS patients with essential hypertension.

Adult↗