Biomedical subjects

L Sun

Publications and source records attributed to L Sun.

At least 73 records · Page 4Linked to original sources

PubMed2001

Simultaneous pharmacokinetic modeling of cocaine and its metabolites, norcocaine and benzoylecgonine, after intravenous and oral administration in rats.

To accurately assess the mechanism of involvement of the active metabolite norcocaine in the effects of oral cocaine, it is essential to determine the rate and extent of the formation of norcocaine. Although this study was designed specifically for this aim, it was also of interest to characterize the metabolite kinetics of benzoylecgonine for comparative purpose. We first characterized the pharmacokinetics of cocaine, norcocaine, and benzoylecgonine by the i.v. route of administration; all three drugs decayed biexponentially. These pharmacokinetic estimates were then used for determination of the formation of norcocaine and benzoylecgonine after i.v. and p.o. (20-40 mg/kg) cocaine administration. Although t(1/2alpha), and t(1/2beta) were similar across the three compounds, the values of volume of distribution in the central compartment and clearance for benzoylecgonine were much smaller than those of cocaine and norcocaine. Norcocaine was not detected following i.v. cocaine; however, serum norcocaine concentrations were as high as those of oral cocaine. Both routes of cocaine administration produced benzoylecgonine. A pharmacokinetic model for the metabolite kinetics was proposed by sequentially adding the models that most adequately described the formation of each metabolite to the model of cocaine. For oral cocaine, the absolute bioavailability was 3.48%, whereas 6.04 and 2.26% of cocaine were converted to benzoylecgonine and norcocaine, respectively, during first-pass absorption regardless of dose. Furthermore, the majority of norcocaine and 92% of benzoylecgonine were formed during the first-pass absorption, leaving 8% of benzoylecgonine produced in systemic circulation. The profile of norcocaine as a metabolite confirmed the involvement of norcocaine in cocaine's behavioral effects.

Administration, Oral↗

PubMed2001

Predicting risk of prostate specific antigen recurrence after radical prostatectomy with the Center for Prostate Disease Research and Cancer of the Prostate Strategic Urologic Research Endeavor databases.

PURPOSE: Biostatistical models to predict stage or outcome in patients with clinically localized prostate cancer with pretreatment prostate specific antigen (PSA), Gleason sum on biopsy or prostatectomy specimen, clinical or pathological stage and other variables, including ethnicity, have been developed. However, to date models have relied on small subsets from academic centers or military populations that may not be representative. Our study validates and updates a model published previously with the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE, UCSF, Urology Outcomes Research Group and TAP Pharmaceutical Products, Inc.), a large multicenter, community based prostate cancer database and Center for Prostate Disease Research (CPDR), a large military database. MATERIALS AND METHODS: We validated a biostatistical model that includes pretreatment PSA, highest Gleason sum on prostatectomy specimen, prostatectomy organ confinement status and ethnicity, including white and black patients. We then revised it with the Cox regression analysis of the combined 503 PSA era surgical cases from the CPDR prospective cancer database and 1,012 from the CaPSURE prostate cancer outcomes database. RESULTS: The original equation with 3 risk groups stratified CaPSURE cases into distinct categories with 7-year disease-free survival rates of 72%, 42.1% and 27.6% for low, intermediate and high risk men, respectively. Parameter estimates obtained from a Cox regression analysis provided a revised model equation that calculated the relative risk of recurrence as: exponent (exp)[(0.54 x Race) + (0.05 x sigmoidal transformation of PSA [PSA(ST)]) + (0.23 x Postop Gleason) + (0.69 x Pathologic stage). The relative risk of recurrence, as calculated by the aforementioned equation, was used to stratify the cases into 4 risk groups. Very low-4.7 or less, low-4.7 to 7.1, high-7.1 to 16.7 and very high-greater than 16.7, and patients at risk had 7-year disease-free survival rates of 85.4%, 66.0%, 50.6% and 21.3%, respectively. CONCLUSIONS: With a broad cohort of community based, academic and military cases, we developed an equation that stratifies men into 4 discrete risk groups of recurrence after radical prostatectomy and confirmed use of a prior 3 risk group model. Although the variables of ethnicity, pretreatment PSA, highest Gleason sum on prostatectomy specimen and organ confinement status on surgical pathology upon which the model is based are easily obtained, more refined modeling with additional variables are needed to improve prediction of intermediate risk in individuals.

Databases, Factual↗

PubMed2001

[Characteristics of N2O emissions from vegetal soils on Fildes peninsula, Antarctica].

The N2O fluxes from the vegetal soils were first measured on the Fildes peninsula, Antarctica, and the total N2O emission was also estimated in the summer 2 months. The daily variations of N2O fluxes appeared single-peak trend under the sunshine or rainy weather conditions but they were irregular under the snow weather conditions and inconsistent with the atmospheric temperatures. The seasonal variations of the N2O fluxes were affected by the temperature and rainfall. The conditions during the transitions between dry and wet seasons improved the N2O emission. The total N2O emissions from moss and lichen soils were 3.7152 kg and 2.5344 kg, respectively. It follows that the vegetal soils are the sources for the atmospheric N2O on the Fildes peninsula, Antarctica.

Antarctic Regions↗

PubMed2001

[Measurement of CO2 concentration in the areas with vegetation cover on the Fildes peninsula, Antarctica].

The average CO2 concentration was above 473.5 mg.m-3 in the areas covered by moss or lichen, greatly higher than the global average CO2 concentration, implying that these areas may be one of the atmospheric CO2 sources. Abnormally high CO2 concentration was relative with vegetal physiological and ecological characters. In the areas covered by moss, the daily variation of the CO2 concentrations was affected by sunshine and temperature and it was also different under the conditions of the different weathers. Sunshine was the main factors influencing the CO2 concentration. The seasonal variation of the CO2 concentration was negatively correlated with atmospheric temperature and positively with rainfall and air relative humidity. This article first presents the variations of CO2 concentration and its influential factors under the Antarctic environmental conditions, which also presents new information for the further study to the Antarctic greenhouse gases.

Air↗

PubMed2001

Changes in vasoreactivity of rat pulmonary artery after 7 d tail-suspension.

OBJECTIVE: To clarify the effects of simulated microgravity on the local regulating function of the pulmonary circulation. METHOD: Rat tail-suspension (TS) was used as the animal model to simulate the effects of microgravity. The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique. RESULT: As for the endothelium-intact vessel rings from TS group compared with those from the control (C) group, the contractile responses of pulmonary artery to potassium chloride (KCl, 10 ~ 70 mmol/L) did not change obviously after 7 d tail-suspension, which were markedly diminished as to phenylephrine (PE, 10(-9) ~ 10(-5) mol/L). The vasodilatory responses to acetylcholine (ACh, 10(-9) ~ 10(-5) mol/L) were markedly enhanced, which did not change obviously as to captopril (Cap, 10(-5) ~ 3 x 10(-3) mol/L). The vasoreactivity of endothelium-removed pulmonary artery rings to all vasoactive agents did not change after 7 d tail-suspension as compared with those from control rats. CONCLUSION: The release of nitric oxide (NO) by rat pulmonary arterial endothelium was enhanced after 7 d tail-suspension. The vasodilatory function of pulmonary artery was enhanced.

Acetylcholine↗

PubMed2001

[Changes of arterial blood pressure during various stages in spaceflight activities].

Arterial blood pressure (BP) is one of the four life signs in human beings, it could reflect cardiovascular function in some degrees. Thus, BP serves as an important cardiovascular parameter during various stages in foreign spaceflight activities. Although the reports about BP are not always in consistency during spaceflight, hypotension commonly occurs during orthostatic stress after spaceflight. The mechanisms of orthostatic intolerance after spaceflight are virtually the same as that of orthostatic hypotension after spaceflight. This paper simply reviewed the reports on BP during various stages in foreign spaceflight activities and the researches on the mechanism of orthostatic hypotension after spaceflight.

Aerospace Medicine↗

PubMed2001

Aortic root replacement.

OBJECTIVE: To report our operative experience with aortic root replacement in 231 patients with aortic root aneurysm and discuss the current indications, methods, and surgical techniques. METHODS: Between January 1994 and August 1999, a group of 231 consecutive patients underwent aortic root replacement at our hospital, with 13 being treated on an emergency basis. There 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 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 having DeBakey type II aortic dissection. Aortic valve regurgitation occurred in all cases. Aortic root replacement was performed with composite valved graft in 229 patients, and in 2 patients the aortic valve was preserved. RESULTS: The hospital mortality rate was 3.03% (7 patients). Early complications included re-exploration for bleeding in 6 patients, pericardial effusion in 9, as well as cerebral infarction, pleural effusion, and pneumothorax in 2 patients each. One hundred and seventy-five patients (78.12%) were followed up, with a mean follow-up time of 15.7 +/- 13.1 months (range, 2 weeks to 65 months). One patient died from lower-limb embolism and renal dysfunction 3 months postoperatively. Three patients died from postoperative anticoagulation accidents. The preoperative and postoperative mean left ventricular end-diastolic diameters were significantly different (68.1 +/- 9.4 mm, range 54 to 112 mm; vs 54.8 +/- 8.2 mm, range 38 to 88 mm; P < 0.001). CONCLUSIONS: Once a diagnosis of acute aortic root dissecting aneurysm is made, the patient should undergo surgery as soon as possible if the general conditions permit. Aortic aneurysm without dissection or with chronic dissection should be operated if the diameter of the aneurysm is greater than 5 cm.

Adolescent↗

PubMed2001

High levels of HER-2 expression alter the ability of epidermal growth factor receptor (EGFR) family tyrosine kinase inhibitors to inhibit EGFR phosphorylation in vivo.

The epidermal growth factor receptor (EGFR) and HER-2 tyrosine kinases have been implicated in the development, progression, and severity of several human cancers and are attractive targets for therapeutic intervention. SU11925 was developed as a small molecule inhibitor of the tyrosine kinase activity of both EGFR and HER-2. In cellular assays, SU11925 exhibited similar potency against EGFR and HER-2, inhibiting EGF-stimulated EGFR autophosphorylation in A431 (human epidermoid carcinoma) cells with an IC(50) of 30 nM and HER-2 phosphorylation in SK-OV-3TP5 (human ovarian carcinoma) cells with an IC(50) of 38 nM. In contrast to its similar activity against the two targets in cellular assays, approximately 10-fold higher plasma concentrations of SU11925 were required to inhibit HER-2 phosphorylation in HER-2-overexpressing tumors compared with EGFR phosphorylation in EGFR-overexpressing tumors in vivo. Consistent with the proposed mechanism of action of this inhibitor, SU11925 inhibited the s.c. growth of EGFR- and HER-2-dependent tumors in athymic mice at doses that produced substantial inhibition of target receptor phosphorylation in vivo. An unexpected finding from these studies was that higher plasma concentrations of SU11925 were required to inhibit EGFR phosphorylation in vivo in tumors that also express high levels of HER-2 than in tumors that express EGFR alone. This observation, which suggests that it is more difficult to inhibit EGFR phosphorylation in vivo in cells that express high levels of HER-2, was confirmed with ZD1839 (Iressa), a selective EGFR inhibitor that also targets the tyrosine kinase catalytic site. The potential clinical implications of this observation are discussed.

Animals↗

PubMed2001

[Clinicopathologic analysis of ovarian serous and mucinous borderline tumors].

OBJECTIVE: To understand the clinicopathological features of ovarian borderline tumors and evaluate the significance of various histological appearances. METHODS: Forty-five patients with borderline tumors were analyzed retrospectively. The stage distribution was stage I, 34 patients, stage II, 4 patients and stage III, 7 patients. RESULTS: Forty-five cases of borderline tumors accounted for 25.4% of ovarian epithelial malignant tumors. The ratio of serous borderline tumors (SBTs) to mucinous borderline tumors (MBTs) was approximately 1:1.3. Nine of eleven SBTs with exophytic growth presented peritoneal implants, of which two were invasive and seven noninvasive. Two SBTs and 1 MBT recurred after 5, 4, and 1 years respectively. Thirty-three cases were followed from 2 to 9 years. The 5-year survival rate was 100% (Kaplan-Meir method). CONCLUSIONS: The prognosis of the SBTs is favorable. SBTs with exophytic growth are often associated with peritoneum implants.

Adenocarcinoma, Mucinous↗

PubMed2001

[Nourishing characteristic of geochemical elements in Antarctic mosses and lichens].

Studies on the nourishing properties of geochemical elements in Antarctic mosses and lichens show that potassium and calcium were the most active elements, while phosphorous was accumulated in the middle part of lichen cells, and participated in organic synthesis. Mosses accumulated sulphur stressly, but took in iron and magnesium negatively. Aluminum and silicon were absorbed passively by lichens. It is concluded that potassium and calcium were the important nutrient elements for the growth of mosses and lichens, sulphur and phosphorous were the middle significant nutrients, while aluminum and silicon were the passively accumulated elements.

Aluminum↗

PubMed2001

[Surgical treatment of DeBakey type I and II aortic dissection].

OBJECTIVE: Aortic dissection is associated with significant mortality and morbidity. Effective methods to treat aortic disection are now available although these lesions still challenge the cardiovascular surgeon. METHODS: From January 1994 to January 2000. 131 patients with DeBakey I, II type aortic dissection underwent surgical treatment. Operations were performed under cardiopulmonary bypass in 59 patients. Hypothermic circulatory arrest was used in 15 patients. Hypothermic circulatory arrest and selective cerebral perfusion was used in 57 patients. A graft replacement of ascending aorta and partial aortic arch was performed in 25 patients, ascending aorta and total aortic arch in 10. 83 patients underwent the Bentall procedure. The Bentall procedure and total aortic arch replacement were performed in 3 patients, the Wheats operation in 4. 4 patients underwent the elephant trunk techniques and 2 patients with the elephant trunk techniques and the Bentall procedures. RESULTS: There were 4 deaths within 30 days after surgery with an operative mortality of 3.05%, and 3 neurological dysfunction undergone hypothermic circulatory arrest. They were recovered within 1 week. CONCLUSION: The operative technique is difficult. Selective cerebral perfusion can provide available protection during surgery of aortic dissection. It prolongs the time allowed to performed the aortic repair.

Adolescent↗

PubMed2001

Monitoring of antegrade selective cerebral perfusion for aortic arch surgery with transcranial Doppler ultrasonography and near-infrared spectroscopy.

OBJECTIVE: To evaluate the safety and efficacy of antegrade selective cerebral perfusion (ASCP) during aortic arch surgery as a means of extending the safe period of systemic circulatory arrest using multimodality neuromonitoring to objectively quantify the physiologic responses. METHODS: In twenty-two patients (all less than age 60) scheduled for repair of an aortic arch aneurysm, preoperative verification of effective collateral perfusion through both the carotid and vertebrobasilar arterial systems was documented with transcranial Doppler ultrasonography (TCD). During cardiopulmonary bypass, the sole arterial inflow from the pump was via the right subclavian artery. The magnitude of ASCP was quantified by TCD using peak middle cerebral artery velocity, while flow adequacy was measured by continuous regional cerebrovenous oxygen saturation (rSO2) using dual-wavelength spatially resolved near-infrared spectroscopy. RESULTS: All patients experienced an uneventful recovery. Flow in the middle cerebral artery became undetectable at ASCP < 5 ml.kg-1.min-1, so adjustments from a 15-20 ml.kg-1.min-1 baseline were used to maintain rSO2 above 50%. Furthermore, ASCP flow was highly correlated (P < 0.01) with both peak middle cerebral artery velocity and rSO2(r = 0.86 and 0.96, respectively). CONCLUSION: Neuromonitoring guided ASCP may be expected to extend the safe period and is at least partly responsible for the absence of neurologic complications in this patient cohort.

Adolescent↗

PubMed2001

Primary studies on heroin abuse and injury induced by oxidation and lipoperoxidation.

OBJECTIVE: To further reveal serious risks of heroin abuse to human body and clarify grave injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers. METHODS: Determined and compared plasma levels of nitric oxide (P-NO), vitamin C (P-VC), vitamin E (P-VE), beta-carotene (P-beta-CAR), lipoperoxides (P-LPO) and erythrocyte activities of superoxide dismutase (E-SOD), catalase (E-CAT), glutathione peroxidase (E-GSH-Px) and erythrocyte level of lipoperoxides (E-LPO) in 137 cases of heroin abusers (HAs) and 100 cases of healthy volunteers (HVs), used linear regression and correlation, stepwise regression and correlation to analyze correlation among heroin-abusing-duration (HAD), daily-heroin-abusing-quantity (DHAQ) with above determination values in the HAs. RESULTS: Compared with the above average values in the HVs group, the average values of P-NO, P-LPO, E-LPO in the HAs group were significantly increased (P < 0.0001), the average values of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT and E-GSH-Px were significantly decreased (P < 0.0001); the analysis of linear regression and correlation showed that with ascending of the HAD and DHAQ in the HAs, the values of P-NO, P-LPO, E-LPO were gradually increased (P < 0.0001), the values of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT, E-GSH-Px were gradually decreased (P < 0.0001); the analysis of stepwise regression and correlation suggested that the correlation among the HAD, DHAQ with the values of P-NO, P-VC, P-VE was the closest. CONCLUSION: The balance between oxidation and antioxidation in the HAs was seriously destroyed, and the injuries induced by nitric oxide and other free radicals, oxidation, peroxidation and lipoperoxidation reactions to the body of HAs gravely exacerbated. In the abstaining from heroin dependence, therefore, it should consider that sufficient quantum antioxidants such as VC, VE and beta-CAR are dosed to the HAs so as to abate the injuries to their bodies.

Adult↗

PubMed2001

Surgical treatment of 52 patients with congenital coronary artery fistulas.

OBJECTIVE: To evaluate the outcome of surgical treatment for congenital coronary artery fistulas (CAF) in 52 patients seen between May 1988 and July 1999. METHODS: Fifty-two patients ranging in age from 9 months 58 years (mean 15.7 +/- 16.4 years) were studied. Thirty-six patients had no other cardiac defects, 9 of those patients were more than 20 years old and presented with symptoms. Only one of 36 patients less than 20 years old had clinical findings before surgery. Sixteen patients had associated cardiac lesions. The site of fistula origin was the right coronary artery in 37 patients (71.2%), and the left coronary artery in 15 patients (28.8%). The sites of CAF drainage were the right ventricle, right atrium, left ventricle, left atrium and pulmonary artery in 22 (42.3%), 16 (30.8%), 6 (11.5%), 3 (5.8%), and 5 (9.6%) patients, respectively. The mean diameter of the fistula in 43 patients with single ostium was 7.34 +/- 4.12 mm. RESULTS: Cardiopulmonary bypass was used in all patients and no patient died. An arteriotomy was made on the anomalous coronary artery and the proximal opening of a fistula was closed within the vessel in 10 patients. Closure of the distal opening of a fistula draining into a cardiac chamber or pulmonary artery was performed in 26 patients. In 16 patients, both the proximal and distal opening were closed. Two and 3 distal opening of a fistula were found in 6 and 3 patients, respectively. No residual shunt was found before patients were discharged from the hospital. Forty patients were followed up for a mean period of 3.14 +/- 1.84 years. The remaining 12 patients could not be contacted during follow-up. No clinical symptoms were found in those patients during follow-up but one patient still presented with ST-T change. CONCLUSION: Early and properly surgical management is safe and effective for congenital coronary fistula.

Adolescent↗

PubMed2001

[A pilot study in treatment of systemic lupus erythematosus by autologous bone marrow transplant].

OBJECTIVE: To explore the clinical effect for treatment of SLE by autologous bone marrow transplantation(ABMT). METHODS: Three patients with refractory SLE were chosen. BM stem cells were harvested from the posterior superior iliac crests under epidural anesthesia and preserved in 4 degrees C. BM stem cells were reinfused after conditioned by CTX (120 mg/kg) and malphalan (140 mg/m(2)) or VP-16 (1.0 g/m(2)). G-CSF was used to help hematopoietic and immunologic reconstitution. RESULTS: These three patients had clinical remission after transplantation; the levels of immunoglobulins declined and complements rose up. Most of the auto-antibodies turned negative. Skin pathology in case 2 showed that the former tissue injury alleviated or disappeared. Moreover, myocardial hypertrophy and pericardial effusion also disappeared. CONCLUSIONS: (1) ABMT is obviously effective for SLE. The duration of remission remains to be decided in long-term follow up. (2) Mechanisms of improvement are possibly related to decrease of immunologic pathological cells in tissues after conditioning, reduction of the level of immunoglobulins and drop of the quantity of auto-antibodies.

Adolescent↗

PubMed2001

Relationship between hyperventilation and intracranial pressure in patients with severe head injury.

With high fatality rate and disability rate, the pathophysiologic changes of severe head injury are complicated. But the method of lowering intracranial pressure (ICP) through artificial hyperventilation is called in question recently. To understand the related changes of the partial pressure of carbon dioxide in artery (PaCO(2)) and the ICP at the acute period of severe head injury, a total of 64 patients with severe head injury were monitored and analyzed on the 3rd day after injury.

Adolescent↗

PubMed2001

[The dynamic changes of NOSmRNA in endothelial cells of aortae and pulmonary arteries in rats under tail suspension].

Objective. Through the observations of dynamic changes of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation and pulmonary circulation under simulated weightlessness, to collect some data for studies of the adaptive mechanisms of local regulation in arterial systems. Method. Wistar rats were -30 degrees tail suspended to simulate the effects of weightlessness. The rats were randomly divided into three groups: control group (CON), 7-day tail suspension group (TS7) and 14-day tail suspension group (TS14). Changes of NOSmRNA expresses in endothelial cells of the thoracic aortae and pulmonary arteries were observed with in situ hybridization technique. Result. The eNOSmRNA and iNOSmRNA of thoracic aortic and pulmonary arterial endothelial cells in TS7 rats increased very significantly. The eNOSmRNA of thoracic aortic endothelial cells from TS14 rats returned to control level, but remained very significantly increased in pulmonary arteries. The iNOSmRNA in pulmonary arterial endothelial cells from TS14 rats decreased very significantly, but that in thoracic aortae returned to the control level. Conclusion. The responses of eNOSmRNA and iNOSmRNA in arterial endothelial cells of systematic circulation to tail suspension were similar, but they were different in pulmonary arterial endothelial cells, which might be due to the difference in the peak course of the shift of fluid from lower body entering the pulmonary or systematic circulation during initial period of simulated weightlessness. It could be a kind of important sign of depressed local regulative function under simulated weightlessness and might contribute to orthostatic intolerance after simulated weightlessness.

Animals↗

PubMed2001

[The study of countermeasures on measles control in infants].

OBJECTIVE: To understand: a) measles antibody levels in purpura and their newborns, and the relation between them, b) maternal transferred measles antibody level of different age group infants, c) immunization rates of success in 6 and 8 month old infants, d) to study measles control countermeasures on infants. METHOD: To test measles IgG antibody levels of infant's blood using ELISA method. RESULTS: Antibody levels of measles in 58 pairs of mother and their newborns, 51 pairs were the same, while 7 pairs were different. Measles antibody levels in newborns was not high and reduced to 50% in 3 months, 20% in 6 months, and 15% in 8 months. The antibody levels in 6 and 8 month olds were low, nearly no protection to children. It was found that rates of immunization success and the antibody distribution were not statistically different between 6 and 8 months olds after measles vaccination. CONCLUSION: It was found that the measles antibody level in most matured women was low. Since mother's measles antibody level has close relation to their newborns, it seems that the newborn's antibody level can be improved by vaccination to matured women. In order to reduce morbidity of infant measles, the age of first vaccination of measles vaccine should be changed from 8 months old to 6 months old in some regions.

Age Factors↗