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Biomedical subjects

S L Sun

Publications and source records attributed to S L Sun.

At least 19 recordsLinked to original sources
PubMed2005

Calcium/poly(9,9-dioctylfluorene) interaction: a theoretical study.

The geometric and electronic structures of poly(9,9-dioctylfluorene) (PFO) oligomer interacting with Ca atoms were studied using Møller-Plesset perturbation theory. A weak interaction with little charge transfer and with a relatively long Ca-C distance (about 4.0 Angstrom) was found when only one Ca atom was attached to a PFO unit. However, when two Ca atoms were adsorbed at a PFO unit, a strong interaction with a shorter Ca-C distance (about 2.67 Angstrom) took place with considerable charge transfer from the Ca atom to the PFO, resulting in significant deformation in the backbone of the PFO oligomer. In the latter case, the frontier orbitals of the PFO were modified. However, the deformed PFO and its modified frontier orbitals could be recovered when oxygen was added, which is in good agreement with experimental observation.

Journal Article↗
PubMed2002

Phase I study of rubitecan and gemcitabine in patients with advanced malignancies.

BACKGROUND: Rubitecan (9-nitrocamptothecin, 9-NC, Orathecin) and gemcitabine have single-agent activity in pancreatic and ovarian carcinoma. We conducted a phase I trial to evaluate the maximum tolerated dose (MTD) and toxicities of this combination in advanced malignancies. PATIENTS AND METHODS: Twenty-one patients with refractory or recurrent malignancies were enrolled in this dose escalation trial. Dose escalation proceeded from a starting level of rubitecan at 0.75 mg/m(2)/day administered orally on days 1-5 and 8-12 in combination with gemcitabine 1000 mg/m(2) administered intravenously on days 1 and 8 of a 21-day cycle. RESULTS: The MTD was defined as rubitecan 1 mg/m(2) administered orally days 1-5 and 8-12, and gemcitabine 1000 mg/m(2) administered intravenously over 30 min days 1 and 8, given every 21 days. Dose-limiting toxicity was myelosuppression including neutropenia and thrombocytopenia. Other side effects included diarrhea, nausea, vomiting and fatigue. Five patients with stable disease were observed among 18 evaluable patients. CONCLUSIONS: The recommended phase II dose is rubitecan 1 mg/m(2) given orally on days 1-5 and 8-12 in combination with gemcitabine 1000 mg/m(2) as a 30-min intravenous infusion on days 1 and 8 of a 21-day cycle.

Adult↗
PubMed2001

Metastatic human hepatocellular carcinoma models in nude mice and cell line with metastatic potential.

Metastatic human HCC model is needed for the studies on mechanism and intervention of metastatic recurrence. By using orthotopic implantation of histologically intact tissues of 30 surgical specimens, a patient-like metastatic model of human HCC in nude mice (LCI-D20) and a low metastatic model of human HCC in nude mice (LCI-D35) have been established. All mice with transplanted LCI-D20 tumors exhibited extremely high metastatic ability including spontaneous metastasis to liver, lungs, lymph nodes and peritoneal seeding. Remarkable difference was also found in expression of some of the invasiveness related genes and growth factors between the LCI-D20 and LCI-D35 tumors. PAI-1 increased gradually following tumor progression in LCI-D20 model, and correlated with tumor size and AFP level. Phasic expression of tissue intercellular adhesion molecule-1 in this model was also observed. Using corneal micropocket model, it was demonstrated that the vascular response induced by LCI-D20 tumor was stronger than that induced by LCI-D35 tumor. Similar report on metastatic human HCC model in nude mice and human HCC cell line with metastatic potential was rarely found in the literature. This LCI-D20 model has been widely used for the studies on intervention of metastasis, including anti-angiogenesis,antisense approach, metalloproteinase inhibitor, differentiation inducer, etc. It is concluded that the establishment of metastatic human HCC model in nude mice and human HCC cell line with metastatic potential will provide important models for the in vitro and in vitro study of HCC invasiveness, angiogenesis as well as intervention of HCC recurrence.

Animals↗
PubMed2001

[Effect of shenmai injection on neurocyte apoptosis and change of cytoplasmic calcium].

OBJECTIVE: To study the neurocyte apoptosis and change of cytosolic free calcium induced by hypoxia/hypoglycemia culture in SH-SY5Y human neuroblastoma cells, and the effect of Shenmai Injection (SMI) on them. METHODS: The neurocyte apoptosis rate was analysed quantitatively by flow cytometry and cytosolic calcium was determined by measuring mean fluorescent value with Fluo-3 flurometry. RESULTS: Hypoxia/hypoglycemia could induce neurocyte apoptosis and increase the cytosolic calcium in SH-SY5Y cells. SMI could inhibit the SH-SY5Y cell apoptosis and lower the concentration of cytosolic free calcium. CONCLUSION: Apoptosis is one of the death pattern of nerve cells. SMI could obviously reduce the hypoxia/hypoglycemia induced apoptosis and calcium overload, thus protect the neurocytes.

Apoptosis↗
PubMed1994

Experimental studies on immune-complex in situ type glomerulonephritis in rabbits treated with mai-luo-tong and natural indigo.

By injection of C-BSA, immune-complex in situ type glomerulonephritis was duplicated in rabbits and treated with Mai-Luo-Tong and natural Indigo. The results showed that proteinuria in the treated groups M and Q was decreased. The difference between group M and control group is statistically significant (P < 0.05). Under light and electron microscope, although glomerular basement membrane was irregularly thickened and subepithelial dense electron deposited in the treated group, but microthrombus, erythrocytes and platelets aggregation and leukocytes impaction were not seen within glomerular capillaries. Also in groups C, Q, M, mesenteric cell count was 99.40 +/- 18.53, 92.87 +/- 17.89, 66.55 +/- 7.75 respectively, the M. Q groups are compared with group C, the result is of statistical significance (P < 0.05) and there is no apparent glomerular fibrosis in the treated groups.

Animals↗
PubMed1994

Conformation therapy using a computer controlled telecobalt unit for advanced cervical carcinoma.

This retrospective analysis evaluates the results of conformation radiotherapy for patients with advanced cervical carcinoma. Between January 1980 and September 1987, 16 patients with high common iliac/para-aortic node metastases from advanced carcinoma of the uterine cervix were treated using conformation radiotherapy. A large area from L1/L2 to the pelvis, with an average length of 23 cm, was treated to a total tumour dose of 5000-5500 cGy, with a daily tumour dose of 180-200 cGy in 28-30 daily fractions, using a computer controlled tracking cobalt unit (CCTCU). Before external beam irradiation, 11 patients underwent laparotomy/hysterectomy, seven were given chemotherapy and eight received brachytherapy. The preliminary results are encouraging. The actuarial 1-year, 3-year and 5-year survival rates after treatment were 81%, 44% and 37%, respectively. The locoregional control rate was 62.5%. None of the patients relapsed in the para-aortic nodes. All patients tolerated the large area of tracking irradiation therapy very well. None had any severe acute or delayed radiation complications. Use of the conformation radiotherapy technique to include the pelvic and para-aortic nodes has been shown to be an effective form of radiotherapy with minimal morbidity.

Adult↗
PubMed1993

[Research on immune complex in situ type glomerulonephritis treated with mai-luo-tong in rabbits].

Applying c-BSA to duplicate immune complex in situ type glomerulonephritis in rabbits and treating it with Blood Circulation Promoting and Stasis-Removing Drugs Mai-Luo-Tong, the results showed that proteinuria in the treated group was decreased significantly, as compared to the control group (P < 0.01). Under light and electron microscope, although glomerular basement membrane was irregularly thickened and subepithelial dense electron deposits were found in both groups, but histopathologic damage in the treated group less than that of control one. In the treated group micro-thrombus, erythrocytes and platelets aggregation, leukocytes impaction were not seen within glomerular capillary. Also in the treated group mesangial cell proliferation and granulocyte infiltration were decreased significantly (P < 0.01) and there was no apparent glomerular fibrosis in former group.

Animals↗
PubMed1991

Electroacupuncture in rats: evidence for naloxone and naltrexone potentiation of analgesia.

Low frequency electroacupuncture (EA) analgesia has been thought to be mediated by endogenous opioids. Among other lines of evidence, it has been reported that EA stimulation delivered at 2 and 2-15 Hz in rats could be blocked or partially antagonized by naloxone (NAL) and naltrexone (NTX). In contrast, experiments in one of our laboratories (D.J.M.) showed that NAL did not inhibit 2 Hz, and even potentiated 125 Hz EA analgesia. In an attempt to resolve these discrepancies, we conducted joint experiments in the U.S.A. and in China using the methods which previously yielded NAL reversibility of EA analgesia. In no experiment did opiate antagonists block or reduce EA analgesia. On the contrary, we found that, in most experiments, NAL and NTX potentiated 2 and 2-15 Hz EA analgesia respectively. The potentiation occurred independently of laboratory methods, geographic location of the experiment, strain (Chinese or American), tail temperature, sex, and weight of rats. This potentiation suggests the existence of an opioid anti-analgesic system or that NAL and NTX acquired analgesic properties following EA. These results indicate that EA analgesia in rats is a variable phenomenon even when laboratory methods are rigorously replicated. The EA stimulation may activate multiple conflicting neural circuits which interact and ultimately modulate the analgesic outcome.

Aging↗
PubMed1991

Effect of low- and high-frequency TENS on Met-enkephalin-Arg-Phe and dynorphin A immunoreactivity in human lumbar CSF.

Transcutaneous nerve stimulation (TENS) treatment was given for 30 min to 37 patients divided into 3 groups of 10 patients and 1 group of 7 patients. Two groups received low-frequency (2 Hz) and the other 2 groups high-frequency (100 Hz) stimulation. A diagnostic lumbar cerebrospinal fluid (CSF) sample was obtained immediately before and after stimulation. The CSF samples were subjected to analysis of immunoreactive (ir) opioid peptides, Met-enkephalin-Arg-Phe (MEAP) from preproenkephalin and dynorphin A (Dyn A) from preprodynorphin, respectively. Low frequency TENS applied on the hand and the leg resulted in a marked increase (367%, P less than 0.05) of ir-MEAP but not ir-Dyn A, whereas high-frequency (100 Hz) TENS produced a 49% increase in ir-Dyn A (P less than 0.01) but not ir-MEAP. This is the first report in humans that 2 Hz and 100 Hz peripheral stimulation induces differential release of peptides from preproenkephalin and preprodynorphin, respectively.

Adult↗
PubMed1991

[Disposition of 3-(N-piperidinomethylarino)methyl-rifamycin SV (FCE 22250) in rats].

After rats being given ig FCE 22250 5, 10 and 25 mg.kg-1, the plasma peak times (Tmax) were 12-14 h, the max plasma concentrations (Cmax) were 3.0, 5.6 and 12 micrograms.ml-1 respectively, and the half-lives of elimination (T1/2) were 24-26 h. The apparent volumes of distribution of the three doses were about 1 L.kg-1, suggesting that FCE 22250 in blood and in tissue was balanced. Total body clearance rate of each of the three doses was 29 ml.kg-1.h-1. The ig absolute bioavailability ranged from 69-84%. Its distribution in rats was as follows: the highest in liver, next in lung and then in fat, kidney, intestine, spleen, lymphaticode, heart, muscle, testis, the lowest in brain. It was eliminated mainly via the bile with feces. The human serum protein binding rate of FCE 22250 was 96.2%. It was shown that the rate was not correlated with drug concentration in serum under our experimental conditions.

Animals↗
PubMed1990

The effect of volume of epidural morphine on postoperative analgesia in patients undergoing cesarean section.

Ninety paturients undergoing elective cesarean section were included in this randomized study to compare the influence of the injected volume of epidural morphine (EM) on postoperative analgesia. Three similar groups of patients (n = 30 each) received 2 mg EM in 2 ml, 10 ml, and 20 ml saline respectively one hour after the last dose of 2% lidocaine. Pain scores (0-10) at rest (including uterine contraction pain) at the 2nd, 4th, 8th, 12th, 18th, and 24th h were compared among the three groups. There were no statistically significant differences of pain score among the three groups although lower pain score was present in the 20 ml group since the 8th h and thereafter. Regarding the number of patients who requested additional meperidine for pain relief 3 in 2 ml group, 2 in 10 ml group and 1 in 20 ml group respectively. The result may suggest that the influence of the injected volume of EM on postcesarean analgesia is not obvious.

Adult↗
PubMed1989

[The role of selective bronchial arterial infusion in the comprehensive treatment of advanced bronchial carcinoma].

Bronchial arterial infusion (BAI) of cisplatinum and procaine was performed in 20 patients with confirmed, advanced bronchogenic cancer. The short-term response to BAI and survival period were reported. The responsive rates of CR and PR are 65% (75% in small cell carcinoma and 65% in squamous cell carcinoma). The overall mean survival period is 11.5 months (8 months in small cell carcinoma and 12 months in squamous cell carcinoma). We would like to point out that the comprehensive treatment based on BAI should be emphasized in order to improve the survival period. BAI followed by radiation therapy have an effect on completing each other in the therapy of squamous cell carcinoma. But, BAI should take the second place in treatment of small cell carcinoma.

Adult↗
PubMed1989

[High and low frequency electroacupuncture analgesia are mediated by different types of opioid receptors at spinal level: a cross tolerance study].

Previous studies have shown that rats subjected to low or high frequency electroacupuncture (EA) stimulation release enkephalins or dynorphins respectively to produce analgesia. This conclusion was tested in the present study by using cross tolerance technique for further analysing their receptor mechanisms. The main results were as follows: (1) In rats subjected to 2 Hz EA for 6 h, there was a gradual decrease in the analgesic effect, leading to a state of tolerance to 2 Hz EA analgesia. These rats, however, still responded to 100 Hz EA. Likewise, rats made tolerant to 100 Hz EA were still effective to 2 Hz EA stimulation, showing not significant cross tolerance between 2 Hz and 100 Hz EA analgesia. (2) Rats made-tolerant to 100 Hz EA analgesia showed a diminished response to intrathecal dynorphin A (1-13), a kappa agonist, whereas the analgesic effect of the delta agonist [D-Pen2, D-pen5] enkephalin (DPDPE) remained intact. (3) Rats made tolerant to 2 Hz EA analgesia showed a cross tolerance to DPDPE, but not to dynorphin A (1-13). Results obtained from aforementioned cross tolerance studies suggest that 2 Hz and 100 Hz EA analgesia are mediated by delta and kappa opioid receptors, respectively, at the spinal cord of the rat.

Acupuncture Analgesia↗
PubMed1987

Detection of small cell lung cancer bone marrow involvement by discontinuous gradient sedimentation.

Marrow involvement by small cell lung cancer (SCLC) is detected in 10-23% of patients at initial diagnosis by marrow aspirate and biopsy techniques. To improve the detection and potentially monitor marrow involvement by SCLC we have attempted to concentrate malignant cells with clonogenic potential on a discontinuous density gradient (DDG). The bone marrow from 43 patients with SCLC (36 with histologically negative marrow aspirates and biopsies) were separated on a Ficoll-based DDG. Samples were also separated by conventional Ficoll-diatrizoate (FD) (density, 1.077) gradient sedimentation. The cellular interphase from three fractions (F X) corresponding to specific densities 1.050 (F X 1), 1.055 (F X 2), and 1.060 (F X 3) as well as cells separated by Ficoll-diatrizoate (F X FD) centrifugation were isolated and 2.5 X 10(5) cells from each fraction were cultured in 2 ml of 0.3% agar in McCoy's media with 10% fetal calf serum, 2.5 micrograms transferrin, 1 microgram insulin, and 1% penicillin-streptomycin. Colony growth was assessed after 14 days of culture at 37 degrees C and 6% CO2. Tumor colony growth was seen in eight of 36 (22%) patients with histologically negative marrows as well as in four of seven (57%) patients with known involvement. Mean colony growth per 2.5 X 10(5) cells for all 12 patients was 4.3 colonies for F X 1; 8.8 for F X 2; and 2.7 for F X 3. In contrast mean growth from the F X FD was 1.0 colonies. Cells with clonogenic potential could be demonstrated from F X 2 and F X 3 in seven of 12 and eight of 12 patients, respectively; in F X FD four of 12 patients had tumor growth. We conclude that separation of marrow samples by DDG concentrates malignant cells with clonogenic potential at least 8-fold compared to FD separation and that the sensitivity of the clonogenic assay in detecting marrow involvement by SCLC is enhanced by DDG sedimentation.

Biopsy↗