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Biomedical subjects

Y R Li

Publications and source records attributed to Y R Li.

At least 19 recordsLinked to original sources
PubMed1994

Studies on structural changes of collagen in silicosis.

In order to provide scientific information on the prevention and treatment of silicosis, studies about changes of silicotic collagen in lungs were carried out. In this paper, we present experiments about the structural changes of collagen in silicotic lungs of rats and patients. These included electron microscopy, circular dichroism and infrared spectroscopy studies of collagen fibers. The results indicated that fibers of silicotic collagen were shorter in length, smaller in diameter and decreased in alpha-helix content. The -Si-O-R- group and -OH group were found increased and -C-C- backbone shortened. The increase of -Si-O-R- group indicated that silica formed linking bridges between collagens which may be the cause of progressive enlargement of nodules.

Animals↗
PubMed1994

A study on cellular reactions and fibrogenic effects of mineral dusts.

In vivo cytotoxicity including cellular metabolic activity, lysozyme content and total protein content in rat bronchoalveolar lavage, capacity of interleukin-1 released from rat pulmonary cells and fibrogenic effects evaluated from rat lung dry weight, collagen content of the whole lung and pathological grading induced by mineral dust were assayed. The results showed that: (1) The relationship among in vivo cytotoxicity, interleukin-1 release, fibrogenic effects on the lung induced by mineral dusts correlated well with the free SiO2 content in mineral dusts in most (but not all) cases; (2) The biological harmful effects of mixed dusts were not simply the additive effect of single dust. In the group of WO3-SiO2 mixture, the fibrogenicity was mainly due to SiO2, tungsten trioxide (WO3) showed neither fibrogenic effect, nor significant potentiality to enhance SiO2 fibrogenicity, while in the group of SnO2-SiO2, SnO2 was suppressive to the effect of SiO2, although the contents of SiO2 in the two mixed dusts were similar.

Animals↗
PubMed1991

Study of BOD microbial sensors for waste water treatment control.

A microbial sensor consisting of immobilized yeast or bacterial cells and an oxygen electrode was developed for the estimation of biochemical oxygen demand (BOD). A flow-through system was used, and the response time was within 20 min. A linear relationship was observed between the relative current decrease and the BOD of the sample solution within the range of 1-45 mg/L. The storage lifetime was greater than 1 yr. The reproducibility was quite good, within 6% fsd at a concentration of 20 mg/L BOD. Satisfactory results were attained when the biosensor was applied to the determination of BOD in brewery-plant and glutamate-plant wastewater and in a river.

Biosensing Techniques↗
PubMed1991

Effect of blocking medial area of nucleus retrofacialis on respiratory rhythm.

Experiments were performed on anaesthetized, vagotomized rabbits. Respiratory movement and phrenic rhythmical discharge were reversibly abolished by the symmetrical injection of 1% procaine into the medial area of the nucleus retrofacialis (mNRF). Blocking other areas of the medulla had no obvious effect on respiratory rhythm, with the exception of the rostral portion of the ventral respiratory group (VRG), which overlaps with the mNRF. When the mNRF was blocked, most inspiratory and expiratory neurons recorded in the VRG and DRG (dorsal respiratory group) gradually started to fire continuously, and no longer exhibited respiratory rhythm. A minority of respiratory neurons was inactivated during apnea. Stimulation of the caudal portion of the DRG and VRG evoked only a short cluster of phrenic discharges instead of rhythmical firing, indicating that the respiratory neurons situated in these areas cannot generate rhythmic activity by themselves. This suggests that the mNRF plays an important role in the genesis and maintenance of basic respiratory rhythm.

Action Potentials↗
PubMed1990

Transporting of sodium and calcium cation in erythrocyte in patients with essential hypertension.

The sodium and calcium cation transport in erythrocyte and their influencing factors were studied in essential hypertensive (EH) patients. The result showed that plasma sodium pump inhibitor, endogenous digitalis-like compound (EDLC), rose in some patients and sodium pump was depressed in the others, but there were no parallel links between EDLC and sodium pump. The patients with normal sodium pump have mainly shown a decrease of their maximal CA++ pump activity and calmodulin (CaM) content in erythrocyte. It indicated that there might be different types of ion transporting defect in EH, and the abnormalities of these cation transports might be an important pathogenesis in EH.

Adult↗
PubMed1990

[Role of the medial region of nucleus retrofacialis of the rabbit in the generation of respiratory rhythm].

The medulla of rabbits were exposed from ventral surface. When 1% procaine (0.3-1.0 microliters) was injected bilaterally through a micropipette into the medial region of nucleus retrofacialis (mNRF), the respiratory movement and phrenic rhythmical discharge could be reversibly abolished in all of 20 rabbits tested. The area related is very limited, about 1.0 x 1.0 x 1.0mm. Histological examination has shown that the effective injected area is mNRF. Discharge patterns of the respiratory-related neurons (RRNs) in mNRF of the rabbit were analyzed. The result showed that there were many E and E-I PS neurones in the mNRF. Blockade of mNRF caused continuous firing of most inspiratory and expiratory neurons recorded in the VRG and DRG and abolishment of respiratory rhythm. The minority of respiratory neurons were inactivated during apnea. Stimulation of the caudal portion of VRG and DRG during apnea could evoke only a short cluster of phrenic discharges instead of rhythmical firing, indicating that respiratory neurons located in these areas can not generate rhythmic activity themselves. The results suggest that an important area of the respiratory rhythm generators may be located in the medial region of nucleus retrofacialis.

Animals↗
PubMed1989

Bod measurement system with flowthrough electrode.

Biochemical oxygen demand (BOD) is one of the most important and widely used parameters in measurement of organic pollution. BOD determination by the conventional method requires five days and is too protracted and complicated for use in process control. We constructed a microbial sensor for BOD estimation consisting of immobilized yeast cells (Hansenula anomala) and an oxygen electrode. The electrode was carefully designed and a flowthrough measuring system constructed. A biosensor response time of less than 15 minutes was achieved. A linear relationship was observed between decrease in current and sample solution (GGA, model waste water) BOD over the range 1-45 mg/l. The biosensor service life exceeded one year, with a relative standard deviation of less than 6% of BOD at a concentration of 20 mg/l.

Biosensing Techniques↗
PubMed1989

[The influence of GABA injected into cerebral ventricle on electrical activities of pain-excitation neurons and pain-inhibition neurons in nucleus parafascicularis of the thalamus of rats].

The influence of intraventricular injection of GABA on electrical activities of PEN and PIN in nucleus parafascicularis of the thalamus of rats was studied. The results showed that GABA could significantly inhibit the electrical discharges of PEN and increase the electrical discharges of PIN. So it was believed that intraventricularly injected GABA could antagonize or partly antagonize the excitatory action of noxious stimuli and might thus produce analgesia.

Animals↗
PubMed1988

Health survey among farmers exposed to deltamethrin in the cotton fields.

A health survey was conducted among spraymen exposed to 2.5% deltamethrin EC in the cotton fields. The subjects were exposed to deltamethrin at concentrations of 0.022-24.070 micrograms/m3 in respiratory zone air and of 0.013-0.347 micrograms/cm2 of skin contact. Results showed that one-half of the 44 subjects examined complained of itching and burning sensations on their faces. A few miliary red papules also appeared on the face of one subject but not sign of acute deltamethrin poisoning was evident on physical examination. There were no significant differences between the subjects examined and the controls in sodium, potassium, and urea contents in the serum, sodium potassium ATPase and serotonin in whole blood, and 3-methyl-4-hydroxymandelic acid and 5-hydroxyindoleacetic acid in the urine. Deltamethrin in the urine of spraymen was below the detection limit (0.20 microgram/liter) of the method used.

Adolescent↗
PubMed1988

Studies on the effect of tetrandrine on microtubules. I. Biochemical observation and electron microscopy.

Microtubules were purified by using two cycles of assembly and disassembly processes on fresh brain homogenates from 30 guinea pigs. The yield was about 60 mg. The effect of tetrandrine on tubulin was determined by spectrophotometric analysis and electron microscopy. In addition, we used the indirect immunofluorescent method including tubulin antibody to locate the presence of microtubules in 3T3 cells by fluorescence microscopy. The effects of colchicine and P204 were studied for comparison at the same time. The results showed that colchicine can effectively depolymerize microtubules, while tetrandrine showed aggregation, and in a different manner. The shape and structure of microtubules were definitely destroyed by colchicine, but were not affected by P204 which protected against the destructive effect of tetrandrine. This result indicated the safety of using a combination of P204 and tetrandrine in the treatment of silicosis.

Alkaloids↗
PubMed1988

Studies on the effect of tetrandrine on microtubules. II. Observation with immunofluorescence techniques.

Microtubules were purified by using two cycles of assembly and disassembly processes on fresh brain homogenates from 30 guinea pigs. The yield was about 60 mg. The effect of tetrandrine on tubulin was determined by spectrophotometric analysis and electron microscopy. In addition, we used the indirect immunofluorescent method including tubulin antibody to locate the presence of microtubules in 3T3 cells by fluorescence microscopy. The effects of colchicine and P204 were studied for comparison at the same time. The results showed that colchicine can effectively depolymerize microtubules, while tetrandrine showed aggregation, and in a different manner. The shape and structure of microtubules were definitely destroyed by colchicine, but were not affected by P204 which protected against the destructive effect of tetrandrine. This result indicated the safety of using a combination of P204 and tetrandrine in the treatment of silicosis.

Alkaloids↗
PubMed1988

Studies on the inhibitory effect of tetrandrine on silica-induced fibrogenesis in vitro.

Two cell culture systems composed of rat peritoneal macrophages and 2BS fibroblasts were used to study the inhibitory action of tetrandrine on collagen and glycosaminoglycan synthesis. The activation of silica-treated macrophage supernatants stimulated collagen synthesis by 2BS fibroblast cells. Tetrandrine had an inhibitory effect on the biosynthesis of collagen and glycosaminoglycans. The increase in the content of hydroxyproline, representing collagen, was verified by comparing it with that of DNA.

Alkaloids↗
PubMed1984

The simultaneous discharges of two neurons in N. Pf and RF and the influences on them by stimulating central gray matter.

This paper employs the method of simultaneous recording of the electric discharges of two neurons with two microelectrodes to study the interrelationship of simultaneous electric activities of pain excitation neurons (PEN) and pain inhibition neurons (PIN) in N. parafascicularis (Pf) of thalamus and reticular formation (RF) of midbrain in 42 rats. The results prove: (i) There are both PEN and PIN in RF in midbrain and they act coordinately; (ii) noxious messages may simultaneously act on PEN and PIN in N. Pf and RF, and the reciprocal coordination of electric activities of these two kinds of neurons is very obvious; (iii) stimulating central gray matter or injecting morphine may weaken the activities of PEN simultaneously, with the opposite effects on PIN.

Action Potentials↗