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Biomedical subjects

L Sun

Publications and source records attributed to L Sun.

At least 145 records · Page 8Linked to original sources
PubMed2000

Linkage of the genes controlling natural killer cell activity to HLA-B.

OBJECTIVE: To study whether there is a relationship between HLA-B alleles and low natural killer(NK) cell activity in Chinese. METHODS: The subjects were 34 unrelated healthy individuals (10 males and 24 females), aged 25-60 years, and 31 individuals (17 males and 14 females) from 11 families, aged 22-70 years, previously genotyped for HLA class I, II, complotypes and haplotypes that were assigned based on family studies. The unrelated individuals were typed for HLA-A, -B antigen by a microcytotoxicity assay and all the subjects were tested for NK cell activity by lactate dehydrogenase (LDH) enzyme-release assay. RESULTS: Statistical analysis showed that 30 lysis unit(LU) was the cutoff value of low and high NK reactors. The frequency of low reactor individuals homozygous for HLA-B was significantly higher than that for those for HLA-DR(P< 0. 05). The associated genes included HLA-B13, B40, B46, B7, B57, defined as NKB1 genes, and HLA-B44 as NKB2 gene. Family studies provide further evidence that the genes controlling low NK cell activity were located in the MHC region and it was a recessive trait. CONCLUSION: There were recessive genes associated with HLA-B controlling low NK cell activity in Chinese. The NKB alleles were partly different from those found in Caucasian.

Adult↗
PubMed2000

Flow cytometry measurements of DNA content in primary and recurrent pterygia.

PURPOSE: To evaluate DNA content and cellular proliferation rates in primary and recurrent pterygia. METHODS: Matched pterygium and superior conjunctiva tissue were obtained in 36 eyes of 36 patients undergoing pterygium excision with conjunctival autografting (24 primary pterygia, 12 recurrent pterygia). Epithelial and fibrovascular layers were separated for analysis. Matched superior conjunctiva obtained at the time of surgery were used as controls. Samples were prepared according to Thompson's method, and flow cytometry was performed with a Becton-Dickinson FACScan. Analysis of histograms and calculations of cell percentages in cell cycle phases were carried out using CellFit software (version 2.0). Mean proliferation indices (MPIs) were compared using the Wilcoxon matched-pair signed-rank test. RESULTS: The MPI of pterygium fibrovascular tissue (13.4) was significantly higher than the MPI of pterygium epithelium (3.1; P = 0.0001). The MPI of pterygium fibrovascular tissue was also significantly higher than that of superior conjunctival fibrovascular tissue (6.0; P = 0.0001). There was no difference in MPI values between pterygium epithelium and superior conjunctival epithelium (3.55; P = 0.12). The MPI of fibrovascular tissue from recurrent pterygium (73.75) was significantly higher than the MPI of fibrovascular tissue from primary pterygium (7.3; P = 0.003). CONCLUSIONS: The finding of high levels of cellular proliferation in the subepithelial fibrovascular layer of pterygium confirms that pterygium is a disorder of excessive cellular proliferation and that the fibrovascular layer is the site of cellular proliferation. Markedly raised levels of cellular proliferation in recurrent pterygium tissue suggest a clinical correlation between fibrovascular tissue upregulation and pterygium recurrence after surgery.

Adult↗
PubMed2000

A clinical investigation on zhi ling tang for treatment of senile dementia.

Zhi Ling Tang (ZLT [symbol: see text], a TCM prescription designed for replenishing essence, supplementing marrow, invigorating qi, warming yang, removing blood stasis and phlegm, tonifying the brain, and invigorating mental activity) was used in 32 cases of senile dementia (SD). After treatment, the levels of serum cholesterol (Tch), triglyceride (TG), and plasma lipid peroxides (LPO) were lowered; the content of high density lipoprotein (HDL) and the activity of superoxide dismutase (SOD) in RBC significantly elevated, the cerebral blood flow was increased; latent period of P300 and P3 waves was shortened while the amplitude of P3 elevated; and topographic electroencephalogram, revised Hasegawa dementia scales (HDS) scores (P < 0.05-0.01) and clinical symptoms were improved. The total effective rate was 81.3%, indicating that ZLT exhibits relatively good therapeutic effects for treating senile dementia.

Aged↗
PubMed2000

Oral cocaine pharmacokinetics and pharmacodynamics in a cumulative-dose regimen: pharmacokinetic-pharmacodynamic modeling of concurrent operant and spontaneous behavior within an operant context.

Despite wide use of cumulative-dosing procedures to evaluate dose-response relations, limited attention has been paid to investigating drug concentration-effect relations. We first characterized the pharmacokinetic (PK) parameters for i.v. (2 mg/kg) and oral cocaine (20 and 40 mg/kg) in rats. Cocaine's concentration-time profile for the escalating cumulative-dose regimen was simulated from PK parameters, dose size (1, 2, 7, 20, and 45 mg/kg by the oral route), and dosing interval (tau, 35 min) as well as validated from blood sampling at various time points. This concentration-time profile was integrated with pharmacodynamic (PD) profiles of differential reinforcement of low rate performance and spontaneous activity (large and small movements) under a differential reinforcement of low rate 45-s schedule. Effects on three behavioral measures were characterized by integrated PK-PD models using the sigmoid E(max) (for increases in shorter response rate or large movements) and inhibitory E(max) (for decreases in density of reinforcement) models. But for the intrinsic differences in baseline and efficacy values among the behavioral endpoints, one set of PD parameters (i.e., potency and Hill factors) predicted concentration-effect relations for the three behavioral indices across all five doses. Concurrent monitoring of operant and spontaneous activity behavior within an operant context provides a novel behavioral paradigm to investigate drug effects on spontaneous activity under conditions where a behavioral contingency exists. Additionally, a cumulative-dosing procedure is efficient for determining the entire dose-response relation and provides an ideal mode to study phenomena such as sensitization or tolerance by varying dose size and/or tau.

Administration, Oral↗
PubMed2000

Heroin abuse and nitric oxide, oxidation, peroxidation, lipoperoxidation.

To further reveal the risks of heroin abuse to human body, and to determine the injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers, we determined and compared plasma values of lipoperoxides (LPO), nitric oxide (NO), vitamin C (VC), vitamin E (VE), beta-carotene (beta-CAR) and erythrocyte values of LPO, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in 114 heroin abusers and 100 healthy volunteers. Using linear regression and correlation as well as stepwise regression and correlation, we also analyzed the effect of the abusing duration, and daily abusing quantity on the above-mentioned biochemical parameters in the heroin abusers. The results showed that, compared with the healthy volunteer groups, the average plasma values of LPO, and NO, and the average erythrocyte value of LPO in the heroin abuser group were significantly increased (P < 0.0001), and the average plasma values of VC, VE, and beta-CAR and the average erythrocyte values of SOD, CAT, and GSH-Px were significantly decreased (P < 0.0001). Analysis of linear regression and correlation showed that with prolonged heroin abusing and with increased daily quantity in the heroin abusers, the plasma values of LPO, and NO, and the erythrocyte value of LPO were gradually increased (P < 0.001), whereas the plasma values of VC, VE, and beta-CAR and the erythrocyte values of SOD, CAT, and GSH-Px were gradually decreased (P < 0.001). Analysis of stepwise regression and correlation indicated that the plasma values of NO, VC and VE were closely correlated with the abusing duration and daily abusing quantity. These results indicate that the balance between oxidation and antioxidation in the heroin abusers was seriously disturbed, and the injuries induced by nitric oxide and other free radicals, through oxidation, peroxidation and lipoperoxidation to the bodies of heroin abusers exacerbated. It is therefore necessary that in abstaining from heroin dependence, the heroin abusers should acquire sufficient quantities of antioxidants such as VC, VE and beta-CAR.

Ascorbic Acid↗
PubMed2000

Combined defect in membrane expression and activation of platelet GPIIb--IIIa complex without primary sequence abnormalities in myeloproliferative disease.

Defects in glycoprotein (GP)IIb-IIIa or in its activation may cause abnormal platelet aggregation and a bleeding diathesis. We report studies in a 67-year-old man with a myeloproliferative disease and markedly abnormal platelet responses. By flow cytometry, platelet binding of two complex-specific anti-GPIIb-IIIa monoclonal antibodies (mAbs), A2A9 and 10E5, was approximately 50% of normal. An enzyme-linked immunosorbent assay (ELISA) using immobilized kistrin showed 18% of normal membrane GPIIb-IIIa complex. By immunoblot analysis, GPIIb and GPIIIa levels in platelet lysates and membranes were near normal. Activation of GPIIb-IIIa, monitored with mAb PAC-1, was markedly decreased (< 20% of normal) in response to ADP, thrombin and platelet-activating factor (PAF); expression of ligand-induced binding sites (LIBS) was < or = 30% of normal. Signal transduction-independent LIBS expression, induced by echistatin, was approximately 60% of normal, suggesting that the integrin present had intact ligand-binding capability. Sequence analysis of GPIIb and GPIIIa cDNA, and platelet mRNA levels for both subunits, were normal. These findings document an acquired combined defect in membrane expression (secondary to a defect in post-translational processing of the complex) and inside-out signalling-dependent activation of the GPIIb-IIIa complex.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

A cardiopulmonary bypass perfusion technique for the surgical repair of aortic type I dissections requiring the elephant trunk procedure.

The effect of cerebral and spinal cord protection by a modified perfusion technique during the elephant trunk procedure was assessed. Between 1997 and 1998, six patients underwent selective cerebral perfusion (SCP) and lower half of the body perfusion (LBP), in which the right subclavian and left femoral arteries were separately cannulated and perfused by individual pump heads. Moderate systemic cooling was used (nasal temp. 20-30 degrees C; rectal temp. 23-26 degrees C). The open distal aortic repair was performed using only the selective cerebral perfusion; while the aortic arch reconstruction was performed using both selective cerebral and lower half of the body simultaneous perfusion. Blood oxygen saturation of the left jugular vein (SjO2) and regional oxygen saturation cerebral (rSO2) in the front region of the brain, was monitored along with the pressure of the left temporal superficial and femoral artery. The mean cardiopulmonary bypass time was 136 minutes, with a mean arrest time of 92 minutes. Mean duration of isolated selective cerebral perfusion was 23 minutes, with flow rates of 5-8 mL/kg/min; a left temporal superficial artery pressure of 50 mmHg; SjO2 65-80%, and rSO2 58-72%. Mean duration of simultaneous selective cerebral and lower half of the body perfusion was 27 minutes; cerebral flow rates 5-8 mL/kg/min; the left temporal superficial artery pressure of 45-50 mmHg; SjO2 70-85% and rSO2 55-76%. At the same time, lower half of the body flow rates were maintained within 30-50 mL/kg/min; with a femoral artery pressure 50-80 mmHg. Mean extubation time was 28 hours; mean ICU time was 4.5 days. There were no neurologic complications in any patient. All patients survived the operation and were discharged from the hospital. This modified perfusion technique of SCP and LBP worked well and provided satisfactory cerebral and spinal cord protection.

Adult↗
PubMed2000

Effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on osteoporosis in ovariectomized rats.

AIM: To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl]tetracycline (XW630) on experimental osteoporosis in ovariectomized (OVX) rats. METHODS: Serum estradiol (E2) content and bone 1-carboxyglutamic acid-containing protein (BGP) content were measured by radioimmunoassay. With undecalcified bone section and tetracycline intraperitoneal labeling, the bone static and dynamic data were studied in right femur samples. RESULTS: After treatment with XW630 2.5 mg.kg-1, serum BGP content increased by 75.7% but there was no change in serum E2 content and uterus weight compared with OVX rats. Compared with OVX rats, the static data of trabecular bone volume/total tissue volume, trabecular bone volume/sponge bone volume, and mean trabecular plate density were enhanced after treatment with XW630 for 13 wk. The dynamic data of single-labeled surface, double-labeled surface, trabecular osteoid surface, and bone formation rate in tissue level in XW630 group were increased and osteoid maturation period was shortened. CONCLUSION: XW630 enhanced bone activation frequency and increased trabecular connectivity, stability, and strength. XW630 stimulated bone formation and inhibited bone resorption with no effect on reproductive system.

Animals↗
PubMed2000

Effects of XW630 on cell proliferation, iNOS activity, and cGMP content in human osteoblast-like cell line TE85.

AIM: To study the effects of 2-[3-estrone-N-ethyl-piperazine-methyl] tetracycline (XW630) in human osteoblast-like cell line TE85. METHODS: [3H]Thymidine incorporation and cell count for cell proliferation, radioimmunoassay for cyclic GMP (cGMP) content, and monitoring the conversion of [3H]arginine for inducible nitric-oxide synthase (iNOS) activity assay. RESULTS: After treatment with XW630 for 48 h, [3H]thymidine incorporation and cell numbers increased by 62.7% and 96.9%, respectively. NG-monomethyl-L-arginine (L-NMMA, an NOS inhibitor) induced a concentration-dependent inhibitory effect on the proliferation after treatment for 48 h. The inhibitory effect was prevented partially by XW630 (1.0 nmol.L-1). After treatment with XW630 for 12-48 h, iNOS activity and cGMP concentration increased in time-dependent manners. CONCLUSION: XW630 stimulated cell proliferation, enhanced iNOS activity and cGMP content in human osteoblast-like cell line TE85.

Bone Neoplasms↗
PubMed2000

[Aortic root replacement of 231 cases].

OBJECTIVE: To discuss the operative indications, methods, and surgical techniques of aortic root replacement for aortic not aneurysm. METHODS: Between January 1994 and August 1999, 231 consecutive patients underwent aortic root replacement in our institution, and 13/231 were treated on an emergency basis. They were 189 men and 42 women, ranging in age from 14 to 69 years. The diameter of the aneurysm varied from 4.5 to 11.0 cm. Among this group, 145 had isolated aortic root aneurysms, 65 suffered from DeBakey type I aortic dissection, and the remaining 21 were diagnosed as DeBakey type II aortic dissection. Aortic valve regurgitation was involved in all patients. Aortic root replacement was performed with composite valved graft in 229 patients, and 2 patients reserved the aortic valve. RESULTS: Hospital mortality was 3.03% (7 patients). The early complications included re-exploration for bleeding in 6 patients, pericardial effusion in 9, and cerebral infarction, pleural effusion and pneumothorax each in 2 patients. One hundred and seventy-five patients (78.12%) were followed up, with a mean follow-up period of 15.7 +/- 13.1 months (range, 2 weeks to 65 months). One patient died from lower-limb embolism and renal dysfunction at 3 months postoperatively. Three patients died from postoperative anticoagulant accidents. The preoperative and postoperative mean left ventricular end-diastolic diameters were significantly different (68.1 mm +/- 9.4 mm, range: 54 to 112; vs 54.8 mm +/- 8.2 mm, range: 38 to 88; P < 0.001). CONCLUSIONS: Aortic aneurysm without dissection or with chronic dissection should be operated if the diameter of the aneurysm is greater than 5 cm. Once a diagnosis of acute aortic root dissecting aneurysm is made, the patient should undergo surgery as soon as possible if the general condition permit.

Adolescent↗
PubMed2000

[Studies on the chemical constituents of Kaempferia marginata].

AIM: To study the chemical constituents of the rhizomes of Kaempferia galanga L. (Zingiberaceae). METHODS: Various chromatographic techniques were used to separate and purify. Their physico-chemical properties and spectral data were used to elucidate the structures. RESULTS: Six compounds were isolated from the hexane extract of K. galanga. Their structures were identified as marginatol (1), 8 (14), 15-sanderacopimaradiene-1 alpha, 9 alpha-diol (2), 8 (14), 15-sanderacopimaradiene-1 alpha, 6 beta, 9 alpha-triol (3), germacrone (4), trans-ethyl p-methoxycinnamate (5) and n-pentadecane (6) on the basis of spectral data (IR, MS, 1H-1H, 13C-1H NMR, NOEs and HMBC). CONCLUSION: Marginatol (1) is a new isopimarene diterpenoid and was elucidated as 8(14), 15-isopimaradiene-6 alpha-ol. Compounds 2, 3 and 4 were isolated for the first time from this plant.

Diterpenes↗
PubMed2000

[The progress in research on the mechanisms of the effects of blood volume reduction on orthostatic tolerance after microgravity or simulated microgravity].

Orthostatic intolerance commonly occurs after spaceflight, but its mechanisms remain to be clarified. It is believed that the reduction of blood volume might be one of the important factors. So the current countermeasures against orthostatic intolerance are aimed to control the changes of blood volume. The main differences between physiological effects of microgravity and simulated microgravity on humans appear in the circulation of the low pressure side and in humoral and electrolyte metabolism. Reflexes elicited from the low pressure side are very important for regulation of the extracellular fluids. The authors postulated that for a further understanding of mechanisms of orthostatic intolerance after spaceflight and to establish appropriate countermeasures against orthostatic intolerance, it is important to study the course of changes of the circulation in the low pressure side and the reflexes thus elicited with more appropriate method of simulation.

Adaptation, Physiological↗
PubMed2000

[Analysis and improvement consideration of the current human experimental models of humoral regulation in microgravity].

The main differences between physiological effects of microgravity in spaceflight and simulated microgravity on humans appeared in the circulation of the low pressure side, in humoral and electrolyte metabolism. For a further understanding of the physiological effects of microgravity, some improvement of the current human experimental models are needed. It is possible to choose more adequate models closer to the situation in microgravity through measuring cardiovascular parameters, fluid regulation and renal excretion variables under head-up tilt (HUT) plus lower body positive pressure condition, or under head-down tilt (HDT) plus upper body negative pressure in various angles and pressure levels.

Adaptation, Physiological↗
PubMed2000

[Counteracting effects of intermittent head-up tilt on simulated-weightlessness induced atrophy of anti-gravity muscles].

Objective. To study the efficacy of intermittent + Gz (45 degrees head-up tilt, HUT) exposures in preventing or alleviating atrophic changes in hind limb muscles induced by simulated weightlessness. Method. Male Sprague-Dawley (SD) rats were assigned randomly to one of three groups: simultaneous control (CON), simulated weightlessness (SUS), and SUS plus 6 h/d HUT (SUS + HUT). Muscles examined included soleus (SOL), medial gastrocnemius (correction from grastrocnemius) (MG), lateral gastrocnemius (LG) and extensor digitorum longus (EDL). Sections were treated with an adenosinetriphosphatase (ATPase) stain or alkaline phosphatase stain. The cross-sectional areas (CSA) of fibers, the relative proportion of type I fiber and the ratio of capillaries/fibers (C/F) were measured using Leica image analysis system. Result. Compared with CON, the wet weight of hind limb muscles in SUS were significantly reduced. The changes of wet weight in different groups were various. The C/F ratios of all muscles were significantly reduced. SUS + HUT rats showed significant increases in SOL and MG wet weight, and the relative counter-effects of intermittent HUT were 93.4% and 34.8%, respectively. In SUS + HUT group, the CSA of both type I and II fibers and relative proportion of type I fibers were completely recovered in SOL, and partially recovered in MG, while the counter-effects were much less obvious in the fibers of LG and EDL. However, HUT resulted in a significant recovery of the C/F ratios in all muscles. Conclusion. The present study demonstrated that intermittent HUT is effective in counteracting the atrophy induced by simulated weightlessness. The result that reactivity to HUT varied among different muscles suggests that the intermittent artificial gravity should be complemented with other countermeasures.

Animals↗
PubMed2000

[Changes in electrocardiogram and cardiac phase during various stages in foreign manned spaceflight activities and the analysis of their possible mechanisms].

Electrocardiography (ECG) is still the only method for continuous medical observation during various stages of foreign manned spaceflight activities, and it also serves as an important item for medical monitoring in the project for manned spaceflight activities in our country. With electrocardiography, pulse or heart rate (one of the four life signs) and cardiac function can continuously be observed. Cardiac phase relative to ECG is a main index reflecting cardiac function. Understanding of the results of ECG and cardiac phase and their mechanisms during various stages of foreign manned spaceflight activities will be helpful in establishing emergency measures in the course of manned spaceflight activities in our country.

Aerospace Medicine↗
PubMed2000

Effect of intravenous nitroglycerin on hemodynamics in infants and children with congestive heart failure.

OBJECTIVE: To understand the effect of intravenous nitroglycerin (NTG) on hemodynamics in infants and small children with congestive heart failure secondary to congenital cardiac defect of left to right shunt. METHODS: Heart rate, blood pressure and total peripheral resistance were monitored continuously. Echocardiography was used to measure ejection fraction, fractional shortening, end-diastolic volume index of left ventricle, pulmonary capillary wedge pressure, pulmonary artery mean pressure and left ventricular wall stress before the use and during 0.5, 1.0, 1.5, 2.5, and 5.0 micrograms.kg-1.min-1 dosages of nitroglycerin (NTG). RESULTS: There was no significant difference in the indexes of heart rate, blood pressure, ejection fraction and fractional shortening of left ventricle, stroke volume index, cardiac output index, end-diastolic volume index before the use and after the use of NTG. Pulmonary capillary wedge pressure decreased from 15.5 +/- 2.3 mm Hg before the use of NTG to 14.3 +/- 2.2 mm Hg after the use of 0.5 microgram.kg-1.min-1 NTG (P < 0.05), minimum to 12.3 +/- 2.4 mm Hg; left ventricular wall stress I, II and III decreased from 407 +/- 65 dyn.cm-2.10(3), 166 +/- 48 dyn.cm-2.10(3), 255 +/- 52 dyn.cm-2.10(3) to 357 +/- 75 dyn.cm-2.10(3), 136 +/- 48 dyn.cm-2.10(3), 218 +/- 52 dyn.cm-2.10(3) (P < 0.05), minimum to 321 +/- 50 dyn.cm-2.10(3), 114 +/- 42 dyn.cm-2.10(3), 187 +/- 42 dyn.cm-2.10(3), respectively. Total peripheral resistance and pulmonary artery mean pressure were decreased when the dosage of intravenous NTG was increased to above 2.5 micrograms.kg-1.min-1 (P < 0.05). There was no statistical difference in the above indexes of the different dosages. CONCLUSION: Congestive heart failure secondary to congenital cardiac defect of left to right shunt in infants and small children is the indication of using intravenous NTG which could improve hemodynamics. There was different selectivity in dosage between arterial and venous vasodilatation, and the change in hemodynamics was independent of dosage. The dosages of 0.5-1.0 microgram.kg-1.min-1 NTG are recommended when the decrease of cardiac preload is the main point of therapy of heart failure.

Dose-Response Relationship, Drug↗
PubMed2000

Changes in airway responsiveness and relative factors in asthma with remission at puberty.

OBJECTIVE: To elucidate the airway responsiveness and its relative factors in asthma with natural remission at puberty. METHOD: The airway responsiveness was evaluated by provocation of methacholine (PC20). Blood sIL-2R, IL-4 and IFN-gamma values in the cultural supernatant of mononuclear cells, eosinophil count, basophil count and basophil releasability were detected in 18 asthmatic cases with remission at puberty (group I), in 20 asthmatics without remission at puberty (group II), and in 30 healthy controls (group III). RESULT: The mean value of PC20 in group I was significantly lower than that in group III (P < 0.01), but still higher than that in group II (P < 0.01). The blood sIL-2R, and eosinophil counts dropped almost to those of group III, significantly lower than those of group II. IL-4 in the culture supernatant of mononuclear cells was similar to group III, but significantly lower than that in group II. However IFN-gamma was also similar to group III, significantly higher than that of group II. The basophil count and positive rate of human basophil degranulation test stimulated by mannitol with hyper-osmolarity were still abnormal, significantly higher than those of group III, and the basophil level was significantly related to the airway responsiveness. CONCLUSION: The asthmatics with remission at puberty have a certain degree of airway hyper-responsiveness that is related to the abnormality of basophil.

Adolescent↗