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Biomedical subjects

T Wang

Publications and source records attributed to T Wang.

At least 721 records · Page 40Linked to original sources
PubMed1990

[Effect of the resin system on dentin bond strength].

The tensile bond strength for four commercial dentin bonding agents (Gluma Dentin Bond, Dentin Adhesive, Dentin Adhesit and Scotchbond) and two experimental dentin bonding agents, which contains different resin system respectively was tested. The range of bond strength to human dentin for the four commercial products is from 2.6 MPa to 6.2 MPa, the Gluma got the best value among them and for the two experimental dentin bonding agents the value is 16.6 MPa and 12.8 MPa. After thermal cycle (5 degrees C/55 degrees C, 30 sec 1000 periods) the bond strength for all materials fell down obviously, but experimental dentin bonding agent No. 2 kept its value in 9.3 MPa.

Adhesiveness↗
PubMed1990

[Effect of moxibustion on the inflammatory reactions of adjuvant arthritics rats].

Adjuvant arthritic (AA) rats were used as the experimental model and the thickness of pedal pad, the circumference and the pathological (light microscopic changes of the ankle joint as well as the plasma content of middle sized molecules (MSM) were studied before and at subsequent experimental days after moxibustion (once a day for 6 days, on Shenque acupoint). The results showed that moxibustion reduced the inflammatory reactions significantly in comparison with that of the control group.

Animals↗
PubMed1990

Role of oxygen-derived free radicals in superior mesenteric artery occlusion shock in rats.

This study was designed to investigate effects of cellular injury mediated by oxygen-derived free radicals on the intestine, heart, liver, kidney and lung tissues during superior mesenteric artery occlusion shock in rats. The animals were divided into four groups: control (Group 1, n = 6), one hour occlusion (Group 2, n = 8), one hour after releasing the clamp (Group 3, n = 8), and two hours after releasing the clamp (Group 4, n = 8). Compared to control values, the contents of malondialdehyde (MDA) in each tissue in Group 2 had 110 significant changes (P greater than 0.05); in Group 3, MDA in the intestine and heart tissues significantly elevated by 62% (P less than 0.05) and 56% (P less than 0.05); in Group 4, MDA in the intestine, heart, liver, and lung tissues increased by 121% (P less than 0.01), 65% (P less than 0.05), 32% (P less than 0.05), and 31% (P less than 0.05), respectively. Plasma lactic acid, beta-glucuronidase and acid phosphatase increased significantly (P less than 0.01). The results showed that oxygen-derived free radical could cause lipid peroxidation damage not only in the intestine tissue, but also in the heart, liver, and lung tissues, suggesting that oxygen-derived free radicals might play an important role in cellular injury during superior mesenteric artery occlusion shock.

Animals↗
PubMed1990

[plants of Coptis from Tibet and Yunnan].

In this paper the relationship of Tibetan Huanglian and Yunnan Huanglian with Coptis teeta has been studied. The distribution and taxonomic features of Tibetan Huanglian are just the same as Coptis teeta, but quite different from Yunnan Huanglian. The results reveal that Tibetan Huanglian and Yunnan Huanglian are different in botanical origin.

China↗
PubMed1990

Oxygen-derived free radicals induced cellular injury in superior mesenteric artery occlusion shock: protective effect of superoxide dismutase.

This study was designed to investigate the beneficial effect of administration of exogenous superoxide dismutase (SOD) on the inhibition of lipid peroxidation and cellular protection during superior mesenteric artery occlusion shock in rats. Wistar rats were anesthetized with sodium pentobarbital (30 mg/kg body weight), and the superior mesenteric artery occlusion shock model was induced by clamping the superior mesenteric artery for a 60-min period and then releasing the arterial clamp. The following parameters were determined: 1) average arterial blood pressure; 2) survival rate and mean survival time (MST); 3) activities of plasma lysosomal enzymes beta-glucuronidase (beta-G) and acid phosphatase (ACP); and 4) the contents of malondialdehyde (MDA) in visceral tissues. The SOD group received 15,000 U/kg body weight SOD intra-arterially 15 min before release of the clamp. The saline group received intra-arterially a corresponding volume of saline given to the SOD group. The superior mesenteric artery of rats in the control group was not clamped. In the saline group, the contents of MDA presented significant increases (P less than 0.05) in bowel and heart tissues at 1 hr after release of the clamp and showed more significant increases (P less than 0.01-0.05) in bowel, heart, liver, and lung tissues at 2 hr after release of the clamp, when compared with control values. However, the contents of MDA in bowel and heart tissues in the SOD group showed significant decreases (P less than 0.05) compared with values in the saline group and had insignificant changes (P greater than 0.05) compared with control values at 1 hr after release of the clamp. The contents of MDA in bowel, heart, and lung tissues in the SOD group were still lower than those in the saline group (P less than 0.05) at 2 hr after release of the clamp, although they were higher than those in the control group (P less than 0.05). The activities of plasma lysosomal enzymes in the SOD group were much lower than those in the saline group at 1 and 2 hr after release of the clamp. The mean survival time of shocked animals was prolonged when treated with SOD. These results suggested that administration of exogenous SOD may protect cells against lipid peroxidation injury mediated by oxygen-derived free radicals, depress the release of lysosomal enzymes, and prolong the mean survival time of shocked animals.

Acid Phosphatase↗
PubMed1990

Bilateral macular holes in sporadic posterior microphthalmos.

The authors report an unusual sporadic case of bilateral posterior microphthalmos in an 8-year-old Chinese girl. Cycloplegic refraction showed hyperopia of 12.5 diopters in both eyes. Anterior segment examination showed normal corneal diameters, open angles, and normal lens thicknesses. Ultrasonography showed short vitreous compartments resulting in short axial lengths of 17.2 mm. Fundoscopy showed full-thickness macular holes associated with radiate retinal striae. This is the first report of bilateral macular hole formation in sporadic posterior microphthalmos. The literature is reviewed.

Child↗
PubMed1990

[Processing technique of American ginseng].

The article deals with a new technique for processing American ginseng cultivated in China by far-infrared and moisture absorption. The qualities of processed product as per ton-quantity (including appearance, physical properties and chemical compositions) show no difference from those of American ginseng imported from U.S.A. and Canada. The mathematical model of dry-loss weight of American ginseng during processing is given in this article.

Amino Acids↗
PubMed1990

Mechanism of angiotensin II action on proximal tubular transport.

Our previous studies have shown that a low dose of angiotensin II (Ang II) stimulates fluid and bicarbonate absorption from the apical side of rat proximal tubule (PCT). These effects can be blocked by Ang II antagonist, (Sar1, Ile8)Ang II. The cellular mechanism underlying Ang II action, however, remained unclear. Thus, this study was designed to investigate the possible role of phosphoinositide turnover in mediating this action of angiotensin. Rat PCT was perfused in vivo with Ringer's solution containing [3H]inulin as a volume marker. Bicarbonate flux (JHCO3) was determined by total CO2 changes between the collected fluid and the original perfusate as analyzed by microcalorimetry. Luminal perfusion of 10(-11) M Ang II stimulated both JHCO3 and fluid reabsorption. These effects could be blocked by 10(-3) M amiloride and 10(-5) M ethylisopropylamiloride. Luminal perfusion of 4 beta-phorbol-12-myristate-13-acetate (10(-8) M) also stimulated both fluid reabsorption and JHCO3. These effects could also be blocked by amiloride and ethylisopropylamiloride. When both Ang II (10(-11) M) and 4 beta-phorbol-12-myristate-13-acetate (10(-8) M) were perfused together, the stimulatory effects on fluid reabsorption and JHCO3 were not additive. These results suggest that Ang II interacts with its receptors on the apical membrane leading to modulation of the Na-H exchange mechanism in PCT. The phosphoinositide turnover may play an important role in the Ang II action on PCT transport.

Amiloride↗
PubMed1989

Human fetal endometrium--light and electron microscopic study.

Human fetal endometrium was examined by light and electron microscopy. Our study shows the following new morphological aspects: (1) Glands are already present. (2) Endometrium undergoes a maturation process during gestation and at late gestational age resembles late proliferative endometrium. (3) The nuclear bodies are present in cell nuclei throughout gestation. (4) Nucleolar channel systems (NCS) sometimes appear at a late gestational age. (5) Cells with the same morphology as that of endocrine cells are found in the basal layers of endometrium at a late gestational age. The significance of these morphological aspects is discussed.

Embryonic and Fetal Development↗
PubMed1989

[Uterine spiral arteries of the human in gestosis, fetal growth retardation and postmaturity].

The uterine spiral arteries in humans were examined after a normal course of pregnancy and a pathological course with gestosis, fetal growth retardation and post-term birth. We found that the spiral arterioles in normal pregnancy underwent physiological changes, such as invasion of trophoblasts and decomposition of fibromuscular media and elastic tissue. Apart from the post-term birth, we detected in pathological pregnancies a narrowing of the vascular lumen by proliferation of the intima and often little or no physiological changes of the spiral arterioles in the myometrial segment. Compared to normal pregnancies, thrombogenic formation, swelling of the intima and infiltration of erythrocytes were more frequently observed in post-term births. The flow resistance of maternal blood is greater in cases of gestosis and fetal growth retardation than in normal pregnancies, since the uterine spiral arterioles exhibited a narrowing of the vascular lumen and little or no physiological changes of the vascular wall, and in post-term births also increased thrombogenic formation and swelling of the intima. The resulting decrease in uteroplacental blood flow could lead to a functional insufficiency of the placenta.

Arteries↗
PubMed1989

Measurement of thermal expansion coefficient of human teeth.

The coefficient of thermal expansion of specimens from 60 freshly extracted human teeth were measured over the range 10-80 degrees C using a dilatometer. The coefficient increased rapidly above 50 degrees C, but there was no significant variation with tooth age between 10 and 70 years. The average values obtained were 16.96 (SD 3.83) x 10(-6)/degrees C for enamel, 10.59 (SD 2.38) x 10(-6)/degrees C for dentine, 11.90 (SD 4.42) x 10(-6)/degrees C for crowns and 9.44 (SD 0.61) x 10(-6)/degrees C for roots.

Adolescent↗
PubMed1989

Role of endogenous cholecystokinin on vagally stimulated pancreatic secretion in dogs.

Pancreatic exocrine secretion was evoked by electrical stimulation of the vagus nerves (EVS) in dogs to determine whether a gut hormone was responsible for the pancreatic stimulatory activity. In 39 dogs, pancreatic juice was continuously collected to measure volume, bicarbonate, and amylase output, while portal and femoral venous plasma concentrations of gastrin, cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), and pancreatic polypeptide (PP) were determined by radioimmunoassay. EVS produced a significant increase in the pancreatic secretion. Although concentrations of all four peptides significantly increased in plasma, only CCK at the concentration in venous circulation was bioactive in dispersed rat pancreatic acini preparations. This bioactivity of CCK was completely blocked by CR 1409, a CCK-receptor antagonist. The pancreatic secretion by EVS was reduced significantly by intravenous MK-329 (formerly L364,718) to as low as 22% of control values and was completely suppressed by intravenous atropine. The increment in plasma CCK by EVS was also significantly suppressed by atropine. The present study indicates that increased pancreatic secretion by EVS is in part mediated by endogenous CCK.

Amylases↗
PubMed1989

Neural control of distal tubular bicarbonate and fluid transport.

Although previous studies have shown that inhibition of proximal tubular reabsorption of bicarbonate and fluid partially accounts for bicarbonaturia and diuresis observed in the denervated kidney, the role of the distal convoluted tubule in the neural regulation of electrolyte excretion has not been defined. This study was designed to examine the effects of denervation on bicarbonate and fluid reabsorption in the distal convoluted tubules by using in situ microperfusion methods. Early distal tubules were perfused with a solution containing 15 mM bicarbonate at a rate of 12 nl/min, and fluid samples were collected from the late distal tubule. Bicarbonate concentrations were measured as total CO2 by microcalorimetry. The rate of fluid absorption (Jv) was determined using [methoxy-3H]inulin as a volume marker. Before denervation, the rate of bicarbonate absorption (JHCO3-) was 24.7 +/- 2.6 peq.min-1.mm-1, and Jv was 1.80 +/- 0.14 nl.min-1.mm-1. After denervation, marked reductions in JHCO3- (51%) and Jv (60%) were observed. In contrast, sham denervation did not affect JHCO3- or Jv significantly. Our results indicate that the distal convoluted tubule can reabsorb bicarbonate and fluid under physiological conditions. We conclude that the transport processes in this segment of the nephron are regulated by renal nerve activity.

Absorption↗
PubMed1989

[The change of the concentration of substance P in the rats "channel" "point" skin and plasma in the acupuncture analgesia].

Numerous reports indicated that substance p (SP) was a neurotransmitter involved in nociception, it also had analgesic effects in the most part of the central nervous system of all mammals, including man. The numbers of mast cell in human's some acupoint tissue were much higher than the non-acupoint tissue, there was connection between the nerves and mast cells which contained SP particles. Therefore, it is worth studying the change of the concentration of SP in the skin and plasma of rats during the process of acupuncture analgesia. 55 rats were divided into 8 groups; (1) Control group; (2) Heat stimulation group; (3) Electro-acupuncture group; (4) Morphine group; (5) Naloxone (NX) group; (6) NX plus electro-acupuncture group; (7) Non-acupoint electro-acupuncture group; (8) Normal saline solution group. The concentration of SP in the "channel" "acupoint" skin and plasma of rats were determined by radioimmunoassay (RIA). The results show that after acupuncture, the tail-flick threshold is increased, the concentration of SP in the skin and plasma is decreased significantly and the effect of electro-acupuncture is abolished by naloxone (i.p). The results suggest that SP is a transmitter relating to skin nociception and involves the process of pain regulation. Electro-acupuncture can inhibit SP release from the skin and the plasma of rats. There is a functional interaction between SP and endorphin in the effects of electro-acupuncture. That is the SP decreased induced by electro-acupuncture may depend upon the function of opiate receptors.

Acupuncture Analgesia↗