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Biomedical subjects

L Luo

Publications and source records attributed to L Luo.

At least 91 records · Page 5Linked to original sources
PubMed2000

Linear programming based on neural networks for radiotherapy treatment planning.

In this paper, we propose a neural network model for linear programming that is designed to optimize radiotherapy treatment planning (RTP). This kind of neural network can be easily implemented by using a kind of 'neural' electronic system in order to obtain an optimization solution in real time. We first give an introduction to the RTP problem and construct a non-constraint objective function for the neural network model. We adopt a gradient algorithm to minimize the objective function and design the structure of the neural network for RTP. Compared to traditional linear programming methods, this neural network model can reduce the time needed for convergence, the size of problems (i.e., the number of variables to be searched) and the number of extra slack and surplus variables needed. We obtained a set of optimized beam weights that result in a better dose distribution as compared to that obtained using the simplex algorithm under the same initial condition. The example presented in this paper shows that this model is feasible in three-dimensional RTP.

Algorithms↗
PubMed2000

Interleukin-8 levels and granulocyte counts in cervical mucus during pregnancy.

PROBLEM: We measured interleukin-8 (IL-8) and granulocyte counts in cervical mucus to assess local immunity and parturition. METHOD OF STUDY: We detected IL-8 by enzyme linked immunosorbent assay (ELISA) and Western blotting. Granulocytes were counted on a slide glass containing mucus from the external cervical os. RESULTS: ELISA and Western blotting revealed IL-8 in cervical mucus from both nonpregnant and pregnant women. There were no significant differences in cervical mucus IL-8 levels or granulocyte counts between follicular, ovulatory, and luteal phases. However, IL-8 and granulocyte counts were significantly decreased after menopause. IL-8 and granulocyte counts were increased significantly during pregnancy, and were further increased after 38 weeks of gestation and at labor. IL-8 levels were significantly correlated with granulocyte counts, based on the study of 678 samples (P <0.0001). CONCLUSION: IL-8 is involved in the increase of cervical granulocytes and in the process of parturition.

Adolescent↗
PubMed2000

Caspase-3 activation is required for Leydig cell apoptosis induced by ethane dimethanesulfonate.

Previous studies have shown that ethane dimethanesulfonate (EDS) causes the apoptotic death of Leydig cells. The molecular mechanism by which EDS elicits its effect remains uncertain. The present study tested the hypothesis that caspase-3 is involved in the EDS-induced death of rat Leydig cells. Leydig cells were isolated from adult Sprague Dawley at 3, 6, 12, or 24 h after the rats received an EDS injection. Low mol wt DNA fragments that are characteristic of apoptosis were evident by 12 h post-EDS, and the ladder pattern was more pronounced at 24 h. During this same time period, the number of terminal deoxynucleotidyltransferase-mediated deoxy-UTP-biotin nick end labeling (TUNEL)-positive cells increased. Western blot analysis revealed that procaspase-3 was present only at low levels in control Leydig cells, and increased through 6 h post-EDS. By 12 h, procaspase-3 was reduced, whereas the cleaved, active caspase-3 forms appeared at 12 h and increased through 24 h post-EDS. Caspase-3 activity was blocked by caspase-3 inhibitor. In vitro, EDS treatment induced Leydig cell apoptosis. In the presence of cell-permeable caspase-3 inhibitor, however, apoptosis was significantly suppressed, providing further evidence for the involvement of caspase-3 in EDS-induced Leydig cell apoptotic death. Immunohistochemical analysis revealed weak staining for caspase-3 in the cytoplasm of control Leydig cells. From 12-24 h post-EDS, the time interval during which the active forms of caspase-3 appeared, caspase-3 immunoreactivity increased and became localized to the nuclei. Apoptosis and caspase-3 were colocalized in Leydig cells by a histological method that combined TUNEL and caspase-3 immunohistochemistry. In these studies, TUNEL-positive cells all exhibited intense nuclear caspase-3 immunoreactivity, whereas TUNEL-negative cells exhibited weak caspase-3 immunoreactivity in the cytoplasm. Taken together, these results indicate that Leydig cell apoptosis induced by EDS is mediated by caspase-3 activation, and suggest that the translocation of the active caspase-3 forms to the nucleus may be involved.

Animals↗
PubMed2000

split ends encodes large nuclear proteins that regulate neuronal cell fate and axon extension in the Drosophila embryo.

split ends (spen) encodes nuclear 600 kDa proteins that contain RNA recognition motifs and a conserved C-terminal sequence. These features define a new protein family, Spen, which includes the vertebrate MINT transcriptional regulator. Zygotic spen mutants affect the growth and guidance of a subset of axons in the Drosophila embryo. Removing maternal and zygotic protein elicits cell-fate and more general axon-guidance defects that are not seen in zygotic mutants. The wrong number of chordotonal neurons and midline cells are generated, and we identify defects in precursor formation and EGF receptor-dependent inductive processes required for cell-fate specification. The number of neuronal precursors is variable in embryos that lack Spen. The levels of Suppressor of Hairless, a key transcriptional effector of Notch required for precursor formation, are reduced, as are the nuclear levels of Yan, a transcriptional repressor that regulates cell fate and proliferation downstream of the EGF receptor. We propose that Spen proteins regulate the expression of key effectors of signaling pathways required to specify neuronal cell fate and morphology.

Amino Acid Sequence↗
PubMed2000

MRI and CT in the differential diagnosis of pleural disease.

STUDY OBJECTIVE: To explore the role of MRI in the differential diagnosis of pleural disease. PATIENTS: Forty-two patients with pleural disease were included. METHOD: Retrospective study. All patients were examined with both CT and MRI. The morphologic features of pleural lesions and magnetic resonance signal intensity on T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images were evaluated. RESULTS: Mediastinal pleural involvement, circumferential pleural thickening, nodularity, irregularity of pleural contour, and infiltration of the chest wall and/or diaphragm were most suggestive of a malignant cause both on CT and MRI. Pleural calcification on CT was suggestive of a benign cause. Contrary to what has been previously reported in the literature, neither on CT nor on MRI, pleural thickness >1 cm revealed significant difference between malignant and benign pleural disease (p>0.05, chi(2) test). High signal intensity in relation to intercostal muscles on T2-weighted and/or contrast-enhanced T1-weighted images was significantly suggestive for a malignant disease. Using morphologic features in combination with the signal intensity features, MRI had a sensitivity of 100% and a specificity of 93% in the detection of pleural malignancy. CONCLUSION: When signal intensity and morphologic features are assessed, MRI is more useful and therefore superior to CT in differentiation of malignant from benign pleural disease.

Adult↗
PubMed2000

[Experimental study of biologic effects of tumour necrosis factor-alpha on scar-derived fibroblasts].

OBJECTIVE: To investigate the biologic effects of tumour necrosis factor-alpha(TNF-alpha) on scar-derived fibroblasts and to evaluate the role of TNF-alpha in genesis, prevention and treatment of scar. METHODS: Cell strains were established by tissue culture technique. To study the fibroblasts derived from hypertrophic scar and normal dermis, cytoactivity and expression of fibronectin (FN) were determined by MTT, FCM and immunofluorescence. RESULTS: 1. When TNF-alpha is at a high concentration (1,000 U/ml increases), the cytoactivity of hypertrophic scar fibroblasts was decreased significantly, and the positive rate of FN expression was decreased by 11.7%. 2. Cytoactivity of normal dermis fibroblasts was increased with TNF-alpha while the positive rate of FN expression was increased by 9.6%. CONCLUSIONS: TNF-alpha has different biological effects on fibroblasts derived from hypertrophic scar or normal dermis. Studying the regulative mechanisms of TNF on abnormal scar will probably provide a new way to prevent and cure it.

Adult↗
PubMed2000

Development of cytotoxic cerebral edema in rats following intracaudatum injection of tACPD, an agonist of metabotropic glutamate receptors.

OBJECTIVE: To explore the involvement of metabotropic glutamate receptors (mGluRs) in the formation of cerebral edema. METHODS: Male Wistar rats weighing from 250 g to 300 g were used. Trans-1-aminocyclopentane-1, 3-diacarboxylic acid (tACPD), an agonist of mGluRs, was microinjected into the right caudatum. Brain water content was determined by a wet weight/dry weight technique and Na+, K+ and Ca2+ contents were measured by inductive Couple Plasma-9000 at 6 h, 24 h and 48 h post-injection. Extravasation of Evan's blue (EB) into the brain was determined as an indicator of disturbance in the blood-brain barrier (BBB) and endothelial cells. Histologic studies were performed under a Leitz microscope and a Philips EM208s electron microscope. RESULTS: Dose-dependent and time-related increase of brain water was induced after tACPD (10, 50, 500 and 1000 nmol) injection. A significant increase in Na+ and K+ content but not in Ca2+ content was observed. EB extravasation showed no blue stain, indicating no increase in BBB permeability induced by tACPD-injection. Electron microscope study confirmed this finding and revealed remarkable swelling of astrocytes especially endfoot processes of astrocytes around capillaries at 6 h after tACPD-injection. In addition, all changes mentioned above occurred in both caudatum. CONCLUSION: These results indicate that activation of mGluRs by tACPD injected into the caudatum induced cytotoxic brain edema and interfered with astrocyte K+ buffering. This may provide new clues for therapeutic intervention.

Animals↗
PubMed2000

[Changes of tumor necrosis factor alpha and interleukin-6 levels in peritoneal fluid of patients with endometriosis and their effects on human sperm motility and mouse embryo development].

OBJECTIVE: To study the changes of tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) levels in peritoneal fluid of patients with endometriosis and their effects on human sperm motility and mouse embryo development. METHODS: Levels of TNF-alpha and IL-6 in peritoneal fluid and cultured peritoneal macrophages supernatant were detected by enzyme-linked immunoassay (ELISA) in 14 infertile patients (EMT group) with endometriosis proven by laparoscopy and 11 infertile women with normal pelvic organs (control group). The effects of peritoneal fluids obtained from the 2 groups on human sperm motility and development of 2-cell mouse embryo were also studied in vitro. RESULTS: In EMT group the numbers of peritoneal macrophages were higher than those in the control group. Levels of TNF-alpha [(0.33 +/- 0.15), (7.19 +/- 0.60) micrograms/L] and IL-6 [(0.49 +/- 0.68), (1.51 +/- 0.08) micrograms/L] in peritoneal fluid and peritoneal macrophage supernatant were also elevated significantly as compared with those in the controls (P < 0.01). Meanwhile, after four-hour incubation with peritoneal fluids, the percentage of straight-line moving sperm and total sperm motility rate were decreased significantly in EMT group(P < 0.01). Appearance rate of 16-cell mouse embryo was 32.5% in EMT group versus 47.6% in control group after 48 hour coculture with peritoneal fluids(P < 0.01). CONCLUSION: It is likely that elevation of peritoneal fluids cytokines levels in patients with endometriosis may play a role in the pathogenesis of infertility associated with endometriosis.

Animals↗
PubMed2000

[Establishment of in vitro serum-free embryo implantation model].

OBJECTIVE: To observe the growth and implantation of mouse embryos in vitro. METHODS: In order to establish a serum-free coculture system, the whole components of decidual tissue was collected and cultured in vitro. Then 4-day-mouse embryos were added to the well-developed decidual cells, and the following changes of the above system were closely observed under microscope. RESULTS: Mouse embryos were successfully hatched, adhered, implanted and outspreaded under the coculture system. The extraplacental cone and amniotic sac were formed as well. Decidual cells kept stable during the following 4-day coculture. CONCLUSIONS: Decidual cell is an ideal feeder cell for coculture. Our results showed that the modified method of decidual cell culture and the establishment of implantation model were simple, practical and reliable.

Animals↗
PubMed2000

[In vitro effect of danazol on cytokine production of macrophages in peritoneal fluid of infertile patients with endometriosis and its relationship with cytosolic free calicum concentration].

OBJECTIVE: To investigate in vitro effect of danazol on cytokine production of macrophages in peritoneal fluid from infertile patients with endometriosis and its relationship with cytosolic free calicum ([Ca2+]i) concentration. METHODS: Pertitoneal macrophages were obtaind from 14 cases of 24 infertile women with endometriosis (EM group) and 11 cases of 19 infertile women with normal pelvis (control group). Danazol was added to peritoneal macrophages culture reaching final concentrrations of 10 micrograms/L, 100 micrograms/L, 1,000 micrograms/L respectively. Tumor necrosis factor alpha(TNF-alpha) and interleukin-6 (IL-6) levels in macrophage supernatant were detected by enzyme linked immunoassay. The [Ca2+]i of cultured peritoneal macrophage and its changes after danazol addition were also studied. RESULTS: In EM group TNF-alpha and IL-6 levels in peritoneal macrophage supernatant and [Ca2+]i of macrophages were elevated significantly as compared with those in control group. When danazol was added to the cell culture and reached 100 micrograms/L of concentration, the levels of TNF-alpha and IL-6 in cultured macrophage supernatant and the [Ca2+]i of macrophages in EM group decreased significantly (P < 0.01). CONCLUSION: It is suggested that danazol may exert its suppressive effect on endometriosis by inhibiting cytokine release of peritoneal macrophages and may related to decline of [Ca2+]i concentration.

Adult↗
PubMed2000

[Suppressing effect of isoforskolin and forskolin on ocular hypertension in rabbits].

OBJECTIVE: To examine the effects of isoforskolin (isoF) and forskolin (FSK) suspensions administered topically on eyes with ocular hypertension (OHT) and observe the local irritation of the drugs. METHODS: The intraocular pressure (IOP) was measured with pneumotonometer in screened spontaneous or water-loading induced OHT rabbits for evaluation of drug effects, and the irritation indices were recorded as well. RESULTS: In screened OHT rabbits, isoF significantly lowered IOP from 0.5 to at least 4.5 h after the administration (P < 0.05, paired t-test vs. contralateral control eyes), with the maximum decreases of 0.25% and 1% isoF reaching 8.1 mm Hg and 7.0 mm Hg (1 mm Hg = 0.133 kPa) at about 1.5 h later, respectively. In water-loaded OHT rabbits, both 0.06%, 0.1%, 0.25%, 1% isoF and 1% FSK concentration-dependently suppressed the increments of IOP (P < 0.05 with the exception of 0.06% isoF) induced by water-loading, and the peak effects of the optimal concentration of 0.25% isoF and 1% FSK were 7.1 and 6.9 mm Hg (difference of IOP between bilateral eyes) respectively. The results also indicated that 0.25% isoF or FSK suspension had basically no irritation, but 1% induced slight irritating responses during the experiment. CONCLUSION: Both isoF and FSK had suppressing effects on OHT in rabbits with the optimal concentration being 0.25% and 1% respectively; at concentration of 0.25%, topically both drugs had basically no irritation, while 1% of the drugs may induce mild irritating responses.

Animals↗
PubMed2000

[Application of cellulose acetate membrane with the technique of impression cytology combined with immunohistochemical staining for detection of dry eye].

PURPOSE: To evaluate the conjunctival cells by impression cytology with cellulose acetate membrane. METHODS: The expression of the TGF-beta 1 in conjunctival epithelium of 24 patients with dry eye were studied by impression cytology combined with immunohistochemical staining and observed by microscope. RESULT: The cellulose acetate membrane is very transparent under the microscope. Cell's membrane by TGF-beta 1 staining is clear, cytoplasm brown and nuclei blue. CONCLUSION: The method of impression cytology with cellulose acetate membrane is simple and has no injury to the ocular surface. Combined with immunohistochemistry staining, it is suitable to observe the conjunctival cells by this technique which has an important value for the examination of the ocular surface disease.

Aged↗
PubMed2000

[Application of factor analysis to identification of overlapped spectrum in XRF].

EFA method has been used in the processing of qualitative XRF data for metal alloys. With mathematically selected scanning steps and a mathematical model based on suitable training set selection, the method can correctly identify spectrum overlaps. Studies reveal that identification ability can be affected by the number of data points and the concentrations of the overlapping elements.

Alloys↗
PubMed1999

Optimizing computerized treatment planning for the Gamma Knife by source culling.

PURPOSE: A good plan is crucial to the success of gamma knife treatment, which depends not only on parameters such as the number of shots, shot position, collimator sizes, and shot weight, but also on the number of blocked cobalt sources. However, during treatment, a plug is generally used to block those cobalt sources, so the beam cannot reach critical tissues. We present here an automated method to optimize all of those parameters, and to choose a source set, although the beams of some blocked sources do not hit any critical tissue. This strategy is used to achieve a high dose that better conforms to the tumor shape, and at the same time, avoids healthy tissue. METHODS AND MATERIALS: Using a workstation that integrates the gamma knife treatment planning system, we developed a two-step optimization algorithm. First, we used a modified Powell's method to optimize the location of the shot, collimator size, and shot weight; we used simulated annealing to determine if the number of shots was adequate using this parameter. Then, simulated annealing was used to determine which cobalt sources we needed to block. RESULTS: Application of this optimization method in two cases showed that the treatment plan can be much improved when the set of blocked cobalt sources has been taken into consideration. CONCLUSION: Determining the set of blocked sources is necessary in certain cases. This technique better conforms the desired isodose curves to the outline of the target volume and minimizes damage to the surrounding normal tissues.

Algorithms↗
PubMed1999

The pharmacological and functional characteristics of the serotonin 5-HT(3A) receptor are specifically modified by a 5-HT(3B) receptor subunit.

While homomers containing 5-HT(3A) subunits form functional ligand-gated serotonin (5-HT) receptors in heterologous expression systems (Jackson, M. B., and Yakel, J. L. (1995) Annu. Rev. Physiol. 57, 447-468; Lambert, J. J., Peters, J. A., and Hope, A. G. (1995) in Ligand-Voltage-Gated Ion Channels (North, R., ed) pp. 177-211, CRC Press, Inc., Boca Raton, FL), it has been proposed that native receptors may exist as heteromers (Fletcher, S., and Barnes, N. M. (1998) Trends Pharmacol. Sci. 19, 212-215). We report the cloning of a subunit 5-HT(3B) with approximately 44% amino acid identity to 5-HT(3A) that specifically modified 5-HT(3A) receptor kinetics, voltage dependence, and pharmacology. Co-expression of 5-HT(3B) with 5-HT(3A) modified the duration of 5-HT(3) receptor agonist-induced responses, linearized the current-voltage relationship, increased agonist and antagonist affinity, and reduced cooperativity between subunits. Reverse transcriptase-polymerase chain reaction in situ hybridization revealed co-localization of both 5-HT(3B) and 5-HT(3A) in a population of neurons in the amygdala, telencephalon, and entorhinal cortex. Furthermore, 5-HT(3A) and 5-HT(3B) mRNAs were expressed in spleen and intestine. Our data suggest that 5-HT(3B) might contribute to tissue-specific functional changes in 5-HT(3)-mediated signaling and/or modulation.

Amygdala↗
PubMed1999

[Preliminary study on ToRCH epidemic laws in Wuhan region].

OBJECTIVE: To investigate the ToRCH epidemic law in Wuhan region. METHODS: The ToRCH infection in the normal populations of Wuhan region was inspected through a whole year (from Mar. 1997 to Feb. 1998) by detecting the specific IgM antibodies to ToRCH in sera. RESULTS: The results showed that in the whole year, the average positive rates of IgM aitibodies to Toxo, RuV, CMV and HSV were 5.8%, 7.5%, 4.2% and 4.9% respectively. Three characteristics of the ToRCH epidemic in the region were concluded: (1) The epidemic of RuV obviously changed with seasons. Its infection rates were the highest (8.5%, 19.5%, 14.0%) during spring (March, April and May). However, the changes of Toxo, CMV and HSV were not obvious with seasons; (2). The adult infections were mainly recessive, which had no apparent clinical symptoms; (3) The cross infections of the four pathogens were common, the cross-reaction rate of the surveyed year was 2.6%. CONCLUSIONS: RuV infection of pregnant woman may result in congenital malformation of the emlbryo. Accoroding to the seasonal epidemic characteristics of RuV, women in pregnancy had better not to go to the public places during the sping seasons (March, April, May) as far as possible.

Adult↗
PubMed1999

Interchange of catalytic activity within the 2-enoyl-coenzyme A hydratase/isomerase superfamily based on a common active site template.

The structures and chemical pathways associated with the members of the 2-enoyl-CoA hydratase/isomerase enzyme superfamily are compared to show that a common active site design provides the members of this family with a CoA binding site, an expandable acyl binding pocket, an oxyanion hole for binding/polarizing the thioester C=O, and multiple active site stations for the positioning of acidic and basic amino acid side chains for use in proton shuttling. It is hypothesized that this active site template can be tailored to catalyze a wide range of chemical transformations through strategic positioning of acid/base residues among the active site stations. To test this hypothesis, the active site of one member of the 2-enoyl-CoA hydratase/isomerase family, 4-chlorobenzoyl-CoA dehalogenase, was altered by site-directed mutagenesis to include the two glutamate residues functioning in acid/base catalysis in a second family member, crotonase. Catalysis of the syn hydration of crotonyl-CoA, absent in the wild-type 4-chlorobenzoyl-CoA dehalogenase, was shown to occur with the structurally modified 4-chlorobenzoyl-CoA dehalogenase at kcat = 0.06 s-1 and Km = 50 microM.

3-Hydroxyacyl CoA Dehydrogenases↗