Biomedical subjects

L Huang

Publications and source records attributed to L Huang.

At least 127 records · Page 7Linked to original sources

PubMed2001

Pigment epithelium-derived factor (PEDF) in neuroblastoma: a multifunctional mediator of Schwann cell antitumor activity.

Neuroblastoma is notable for its cellular heterogeneity and unpredictable outcome. Tumors are a variable mixture of primitive malignant neuroblasts, more differentiated ganglionic cells, Schwann and endothelial cells. Although often fatal, neuroblastomas can spontaneously regress, possibly due to favorable autocrine and paracrine interactions among these cells. Here, pigment epithelium-derived factor (PEDF), a potent inhibitor of angiogenesis and inducer of neural differentiation, is shown to be produced by ganglionic cells and Schwann cells, but not by more primitive tumor cells. Although undifferentiated neuroblastoma tumor cell secretions were angiogenic primarily due to vascular endothelial growth factor, secretions of Schwann cells were anti-angiogenic due to PEDF. In addition, PEDF was the major factor responsible for Schwann cell's ability to induce tumor cell differentiation in vitro and recombinant PEDF had the same effect in vitro and in vivo. Both the growth and the survival of Schwann cells were enhanced by PEDF. Thus PEDF may serve as a multifunctional antitumor agent in neuroblastomas, inhibiting angiogenesis while promoting the numbers of Schwann cells and differentiated tumor cells that in turn produce PEDF, suggesting that its clinical administration could stimulate a multifaceted antitumor feedback loop with the potential to limit and possibly regress tumor growth.

Angiogenesis Inhibitors↗

PubMed2001

New supports for enzyme immobilization based on copolymers of vinylene carbonate and acrylamide.

In this study, a series of beadlike and hydrophilic supports containing reactive cyclic carbonate groups for enzyme immobilization were prepared via reverse-phase suspension copolymerization of the aqueous solutions of vinylene carbonate (VCA), acrylamide (AA), and N,N'-methylene bisacrylamide in paraffin oil. The supports were used as a matrix for immobilization of trypsin and showed a considerable capacity to couple with trypsin and reasonable retention of activity for the immobilized trypsin, depending on the immobilization conditions, such as the content of VCA structural units, reaction time, and pH of the medium.

Acrylamide↗

PubMed2001

The histogenesis of giant cell tumour of bone: a model of interaction between neoplastic cells and osteoclasts.

Giant cell tumour of bone (GCT) is a benign primary neoplasm of a bone characterised by distinctive clinical, radiological and pathological features. Females are slightly more often affected than males, and the majority of patients present between the ages of 20 and 50. GCT is locally aggressive and produces expansive and lytic lesions, most commonly in the epiphyses of long tubular bones. Histologically, it is composed of oval and spindle mononuclear cells, uniformly distributed amongst which are large multinucleated osteoclast-like giant cells. Although the term "Giant Cell Tumour" (and the erroneous historical term 'osteoclastoma') may imply that it is the multinucleated giant cells which are responsible for the proliferative capacity of the tumour, there is evidence that the stromal-like cells, the major component of the mononuclear cell population, represent the true neoplastic component of the neoplasm. The diagnosis and management of conventional GCT are often challenging and there is considerable current interest in its pathobiology. The precise histogenesis of GCT and the nature of its varying cellular constituents have remained a matter of some controversy. Factors influencing the clinical course and biological aggression of GCT are also unclear. In this selective review, the clinicopathological characteristics of GCT are summarised and current areas of interest in the study of the neoplasm are presented and discussed. Lastly, a hypothetical model of the mechanism of histogenesis and the biological behaviour of GCT is presented.

Animals↗

PubMed2001

Thrombin promotes fibroblast proliferation during the early stages of experimental radiation pneumonitis.

Huang, L., Ogushi, F., Tani, K., Ogawa, H., Kawano, T., Endo, T., Izumi, K., Ueno, J., Nishitani, H. and Sone, S. Thrombin Promotes Fibroblast Proliferation during the Early Stages of Experimental Radiation Pneumonitis. Radiat. Res. 156, 45-52 (2001). To clarify the role of thrombin in the pathogenesis of radiation-induced pneumonitis, we measured the thrombin activity and fibroblast growth-inducing activity in bronchoalveolar lavage fluid obtained from the irradiated lungs of rats at 1, 2, 4, 8 and 18 weeks after irradiation. Thrombin activity was not detected in the bronchoalveolar lavage fluid from unirradiated rats, but the bronchoalveolar lavage fluid from irradiated rats showed significantly increased thrombin activity which reached a maximum at 4 weeks after treatment. Higher fibroblast growth-inducing activity was detected in the bronchoalveolar lavage fluid from irradiated rats at 4 and 18 weeks than in fluid from unirradiated rats. Bronchoalveolar lavage fluid from irradiated rats that were pretreated with the thrombin inhibitors antithrombin III and argatroban showed significantly inhibited fibroblast growth-inducing activity and thrombin activity at 4 weeks. However, these thrombin inhibitors did not inhibit fibroblast growth-inducing activity in bronchoalveolar lavage fluid from irradiated rats at 18 weeks. Purified rat thrombin similarly induced proliferation of fibroblasts derived from irradiated and unirradiated rats. These findings suggest that thrombin may play an important role as a fibroblast growth-inducing factor during the early stages of radiation pneumonitis.

Animals↗

PubMed2001

A new kinetic model for thermal inactivation of microorganisms: development and validation using Escherichia coli O157:H7 as a test organism.

A new kinetic model has been proposed to simulate the nonlinear behavior of survivor curves frequently observed in thermal inactivation of microorganisms. This model incorporates a time component into the first-order inactivation kinetics and is capable of describing the linear, convex, and concave survivor curves. The model was validated using Escherichia coli O157:H7 as a test microorganism. Ground beef (93% lean) samples inoculated to 10(7) to 10(8) CFU/g of meat were subjected to immersion heating at 55, 57.5, 60, 62.5, and 65 degrees C, respectively, in a water bath. All the survivor curves in this study showed upward concavity. Linear and nonlinear regressions were used to fit the survivor curves to the linear first-order inactivation kinetics and the proposed model. Analyses showed that the new kinetic model provides a much better estimate of the thermal inactivation behavior of E. coli O157:H7 in ground beef.

Animals↗

PubMed2001

Multidrug resistance p-glycoprotein 2 is essential for the biliary excretion of indocyanine green.

Multidrug resistance P-glycoprotein 2 (Mdr2) is a phospholipid translocator in the canalicular membrane that is essential for the formation of biliary phospholipid vesicles and mixed lipid/bile salt micelles. Incorporation into biliary vesicles and micelles is thought to contribute to the hepatobiliary excretion of certain hydrophobic organic anions, such as indocyanine green (ICG). The present studies characterized the biliary excretion of two hydrophobic organic anions, ICG and estradiol-17beta(beta-D-glucuronide) (E(2)17G), in the single-pass isolated perfused liver and the biliary excretion of glutathione (GSH) in vivo in wild-type and Mdr2-/- female mice. The biliary excretion of ICG (0.4 micromol) was reduced by 90%, while the biliary excretion of total GSH was decreased by 65% in Mdr2-/- mice relative to wild-type mice. In contrast, the biliary excretion of E(2)17G (0.1 micromol) was increased by 30% in Mdr2-/- mice. These data indicate that the absence of Mdr2 differentially influences the biliary excretion of these organic anions and suggest that phospholipid vesicles and mixed micelles in bile are essential for the biliary excretion of ICG.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

Induction of P-glycoprotein and cytochrome P450 3A by HIV protease inhibitors.

P-Glycoprotein (Pgp) and cytochrome P450 3A (CYP3A) are important enzymes affecting the disposition of HIV protease inhibitors (HIV PIs). After multiple dosing experiments in rats, decreases in the plasma concentrations and area under plasma concentration-time curve (AUC) for HIV PIs have been observed. The purpose of these studies was to determine the changes in Pgp and CYP3A expression and HIV PI plasma exposure after multiple doses of HIV PIs. Male rats were orally dosed with an amprenavir prodrug (450 mg/kg/day amprenavir-equivalent) or nelfinavir (175 mg/kg/day) for 1 or 14 days. Relative to day 1, the C(max) and the AUC for amprenavir at day 14 were decreased by 33 and 51%, respectively. Similarly, the plasma concentration of nelfinavir at 1 h after the last dose (C(max)) was reduced by 52% after multiple doses. Compared with controls, dosing of amprenavir for 14 days increased intestinal Pgp and hepatic CYP3A protein levels by 59 and 151%, respectively, but did not alter intestinal CYP3A protein levels. In contrast, amprenavir treatment did not result in an increase in hepatic CYP3A activity. Nelfinavir treatment increased expression of intestinal Pgp and hepatic CYP3A levels by 83 and 85%, respectively, but not hepatic Pgp or intestinal CYP3A. HIV PIs also induced Pgp expression in the LS174T human intestinal cell line. These results indicate that HIV protease inhibitors induce both intestinal Pgp and hepatic CYP3A and suggest that induction of Pgp and CYP3A is a possible mechanism reducing drug exposure after multiple doses.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Taking the pulse of Internet pharmacies.

Like most businesses, online pharmacy companies will only be successful if they make sure customers are satisfied with the service they receive. But what attributes of service quality lead to satisfaction and dissatisfaction? This study identified 19 Internet pharmacy service quality dimensions in three categories: (1) product cost and availability, (2) customer service, and (3) the online information system. Our analysis uncovered attributes that tend to determine consumer satisfaction and points out ways to improve overall service quality in the Internet pharmacy arena.

Consumer Behavior↗

PubMed2001

Boron supply into wheat (Triticum aestivum L. cv. Wilgoyne) ears whilst still enclosed within leaf sheaths.

The present study investigates whether there is significant remobilization of (10)B previously loaded in the flag and penultimate leaves into the young, actively growing ear enclosed within the sheaths of flag and penultimate leaves. It also explores whether B transport into the enclosed ear declines when air humidity in the shoot canopy increases. After 5 d (10)B labelling during the period from early to full emergence of the flag leaf, the plants were transferred into nutrient solutions containing either 10 microM (11)B or no added B for 3 d. Regardless of the subsequent B supply levels to the roots, (10)B contents in the ear continued to increase by up to 5-fold 3 d after the end of (10)B supply in the nutrient solution. During these 3 d, the ear experienced a rapid increase in biomass. However, the majority of B in the ear during the 3 d treatment period was from the newly acquired (11)B from root uptake, rather than retranslocation of (10)B previously deposited in the leaves. By comparing the relative distribution of (10)B, Rb (xylem-to-phloem transfer marker) and Sr (xylem-marker) in the ear and the flag leaf, the distribution of (10)B resembled that of Rb more than Sr. Canopy cover treatment greatly suppressed leaf transpiration and decreased the amount of newly acquired (10)B in the flag leaf and the ear, but not in the upper stem segments. The results suggest that whilst the young ear was still fully enclosed within the leaf sheaths without any significant transpiration activity, B transport into the ear is predominantly dependent on the long-distance B transport in the xylem driven by leaf transpiration and, therefore, on concurrent B uptake from the roots.

Biological Transport↗

PubMed2001

Variable tinted spectacle lenses: a comparison of aesthetics and visual preference.

PURPOSE: To determine the correlation between the aesthetics of lens tints preferred for cosmesis and lens tints preferred for viewing. METHODS: Thirty-five subjects (mean age: 25; 49% male, 51% female) with no significant ocular pathology participated in the study. Median visual acuity was 20/20. Color vision testing was performed on each subject using Ishihara plates, and those with abnormal scores were excluded from the study. Subjects were shown nine pre-selected tinted lenses (50% transmittance) of variable wavelengths. These lenses were mounted on two separate color backgrounds, one white and the other approximating their skin tone. Subjects were asked to choose from each background which tinted lens they would most prefer to wear and which lens they would least prefer to wear. The subjects were then shown a series of eight pictures (four nature photographs and four paintings) with different dominant wavelengths. Subjects were asked to grade the aesthetic effect of a clear lens and each of the nine tinted lenses on the appearance of the pictures. Chromaticity coordinates were calculated for each lens and picture. RESULTS: The blue lens was the most frequently chosen preferred lens to wear, followed by green, purple, and gray. The least preferred lenses were yellow, brown, and pink. For viewing the nature photographs, the clear lens was preferred over any of the tinted lenses. For viewing the paintings, the purple lens was most preferred. The yellow lens was least preferred for both photographs and paintings. CONCLUSIONS: Younger individuals with no significant ocular pathology preferred viewing both nature photographs and paintings through tinted lenses that did not, or only slightly, altered the chromaticity of the image. Whereas a clear lens was favored over the tinted lenses for viewing the photographs, some tinted lenses (purple and pink) were preferred for viewing paintings. There was no correlation between the most favored lens tint chosen based purely on cosmesis and the most favored lens tint based on viewing preference. However, the least preferred lens tint for cosmesis and viewing was yellow.

Adult↗

PubMed2001

Rational use of in vitro P-glycoprotein assays in drug discovery.

P-glycoprotein (Pgp) affects the absorption, distribution, and clearance of a variety of compounds. Thus, identification of compounds that are Pgp substrates can aid drug candidate selection and optimization. Our goal was to evaluate three assays used to determine whether compounds are Pgp substrates. Sixty-six compounds were tested in monolayer efflux, ATPase, and calcein-AM assays. Assay results yielded two categories of compounds. Category I (n = 35) exhibited concordance across the assays. Category II (n = 31) revealed differences among the assays that related to the apparent permeability (P(app)) of the compounds. Within category II, two groups were discerned based on the absence (group IIA, n = 10, nontransported substrates) or presence (group IIB, n = 21, transported substrates) of monolayer efflux. Detection of efflux (group IIB) was associated with compounds having low/moderate P(app) values (mean = 16.6 nm/s), whereas inability to detect efflux (group IIA) was associated with compounds having high P(app) values (mean = 535 nm/s). The calcein-AM and ATPase assays revealed Pgp interactions for highly permeable group IIA compounds but were less responsive than monolayer efflux for low/moderate P(app) compounds of group IIB. All assays detected substrates across a broad range of P(app), but the efflux assay was more prone to fail at high P(app), whereas the calcein-AM and ATPase assays were more prone to fail at low P(app). When P(app) is low, efflux is a greater factor in the disposition of Pgp substrates. The efflux assay is more reliable at low/moderate P(app) and is the method of choice for evaluating drug candidates despite low throughput and reliance on liquid chromatography with tandem mass spectrometry.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

[The complexity measure and its application to EEG analysis].

In this paper are reviewed the conceptions, characteristics and application of the complexity measure in studying EEG. The reviewers expound the advantages and problems of using complexity measure in the analysis of EEG in different physiological states and deem it a new way to study and understand the human brain function.

Algorithms↗

PubMed2001

Autoantibodies to IL-1 alpha in sera from rapidly progressive idiopathic pulmonary fibrosis.

To clarify the clinical significance of autoantibodies to interleukin-1 alpha (IL-1 alpha autoantibodies) in rapidly progressive idiopathic pulmonary fibrosis (IPF), we measured the level of IL-1 alpha autoantibodies in serum of 11 patients on the first hospital day, when patients were admitted due to severe symptoms, and on the 21st hospital day. IL-1 alpha autoantibodies in serum were measured using radioimmunoassay, and the limitation of this assay for IL-1 alpha autoantibodies was 5 ng/ml. These antibodies were detected in 5 of 11 patients on the first hospital day. On the 21st hospital day, these antibodies were detected in all patients, and its level was increased compared with that on the first hospital day. IL-1 alpha autoantibodies that appeared in patients corresponded to that of IgG. The half life of exogenous autoantibodies was investigated following administration of autoantibody rich plasma obtained from healthy blood donors to 6 control patients (CP) and 6 progressive IPF patients. These autoantibody levels in their serum were less than 5 ng/ml before administration. Serum was obtained at the indicated time after administration of IL-1 alpha autoantibodies and the level of these autoantibodies in serum was measured, then the half life was calculated. Half life of exogenous IL-1 alpha autoantibodies in progressive IPF patients was significantly shorter than that in CP (71.3 +/- 31.8 hr vs 352.0 +/- 98.3 hr, p < 0.01). These findings suggested that IL-1 alpha autoantibodies were generated in response to the inflammatory process of rapidly progressive IPF and may act as a regulatory factor for IL-1 alpha.

Aged↗

PubMed2001

Allogeneic peripheral blood stem cell transplantation for leukemia.

OBJECTIVE: To observe engraftment kinetics, the incidence and severity of graft-versus-host disease (GVHD), and clinical outcome on 40 recipients undergoing allogeneic peripheral blood stem cell transplantation (allo-PBSCT). METHODS: From June 1997 to May 1999, forty leukemia patients with a median age of 35 years underwent allo-PBSCT. PBSC were mobilized with G-CSF at a dose of 5 micrograms/kg s.c. every 12 hours for 5 days. A median of 7.7 (2.0-16.8) x 10(6) CD34+ cells/kg was infused into the recipients. Busulfan-cyclophosphamide (BU-CY) was used as the conditioning regimen. All patients received cyclosporine A and either methotrexate (n = 34) or methylprednisolone (n = 6) for GVHD prophylaxis. RESULTS: Engraftment of neutrophils and platelets was achieved at a median of 13 days (9-28 days) and 12 days (7-60 days) respectively. Patients receiving > or = 4 x 10(6) CD34+ cells/kg or given G-CSF post transplant had significantly accelerated neutrophil and platelet engraftment. Acute GVHD occurred in 17 of 40 patients (42.5%), with grade II-IV acute GVHD in 10 patients (25%). Chronic GVHD developed in 21 (9 extensive, 12 limited) out of 30 evaluable patients (21/30, 70%) with a median follow up of 380 days (180-900 days). Transplant related mortality was 17.5% and the relapse rate was 10%. The probability of leukemia free survival at 3 years was 72.5%. CONCLUSION: Allo-PBSCT can provide rapid hematopoietic reconstitution without an increased incidence of acute GVHD, but may be associated with a high risk of chronic GVHD.

Adult↗

PubMed2001

Vascular endothelial growth factor mRNA and its protein expression in decidua after terminating early pregnancy by mifepristone plus misoprostol.

OBJECTIVE: To investigate the action of mifepristone plus misoprostol on decidua at the level of vascular endothelial growth factor (VEGF) mRNA and its protein expression, as well as the mechanism of prolonged uterine hemorrhage after terminating early pregnancy with these drugs. METHODS: Forty-five decidua specimens were obtained from 45 pregnant women with amenorrhea of 6-7 weeks' duration, in which 15 women were treated with mifepristone and 15 were given mifepristone plus misoprostol. Enzyme-linked immunosorbant assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect VEGF protein and mRNA levels in decidua. RESULTS: In all three groups, only the VEGF121 amplification product of 452 bp was visualized. The mRNA and protein levels of VEGF showed no significant differences among the three groups (P > 0.05). CONCLUSION: In humans, early decidua VEGF121 mRNA is the main isoform. The action of mifepristone plus misoprostol on blood vessels in human decidua may be medicated by some factors other than VEGF.

Abortifacient Agents↗

PubMed2001

Tissue-type plasminogen activator and plasminogen activator inhibitor type-1 mRNA and their protein expression levels in human decidua after early pregnancy termination by mifepristone plus misoprostol.

OBJECTIVE: To investigate the mechanism of prolonged uterine hemorrhage after terminating early pregnancy by mifepristone plus misoprostol. METHODS: Forty-five decidua specimens were obtained from 45 pregnant women with amenorrhea of 6-7 week duration. Fifteen women were treated with mifepristone and 15 were treated with mifepristone plus misoprostol. The remaining 15 served as controls. The tPA and PAI-1 mRNA levels were estimated by reverse transcription-polymerase chain reaction. Chromogenic assay and enzyme-linked immunosorbent assay were used to detect tPA activity and PAI-1 protein level in decidua. RESULTS: The activities of tPA in the mifepristone plus misoprostol group and in the mifepristone group were 46.91 +/- 20.74 IU/mg.protein and 64.25 +/- 35.81 IU/mg.protein respectively, lower than those in the normal decidua group (99.76 +/- 58.61 IU/mg.protein, P < 0.05). tPA mRNA levels in the mifepristone plus misoprostol group were the highest (1.43 +/- 0.39) among the groups. In the mifepristone group, tPA mRNA level (0.90 +/- 0.16) was not significantly different from that in the normal decidua group (0.94 +/- 0.17). The protein and mRNA expression levels of PAI-1 were not significantly different among the three groups (P > 0.05). CONCLUSIONS: Mifepristone plus misoprostol decreased tPA activity in human early decidua by post-transcription pathways, which may influence decidua shedding, endometrial angiogenesis, endometrial remodeling, and cause prolonged uterine hemorrhage after drug abortion.

Abortifacient Agents, Nonsteroidal↗

PubMed2001

Magnetic resonance imaging in distinguishing malignant from benign pleural disease.

OBJECTIVE: To explore the role of magnetic resonance imaging (MRI) in distinguishing malignant from benign pleural disease. METHODS: All 64 patients were examined with both computed tomography (CT) and MRI. The morphologic features of pleural lesions and MR 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 on CT and MR images. Contrary to what has been reported in the literature, pleural thickness greater than 1 cm either on CT or on MRI did not reveal a significant difference between malignant and benign pleural disease (P > 0.05, chi-square test). Using morphologic features in combination with signal intensity features, MRI had a sensitivity of 98% and a specificity of 92% in the detection of pleural malignancy. CONCLUSIONS: Compared with those on CT, the morphologic features on MRI allowed a mostly equal and in some cases superior detection and evaluation of the spread of pleural disease. In combination with signal intensity and morphologic features, MRI is very useful in distinguishing malignant from benign pleural disease.

Adult↗

PubMed2001

Neutralization/enhancement of macrophage-tropic SIVmac infection by plasma from macaques infected with macrophage-tropic or lymphocyte-tropic SIVmac.

Plasma from macaques inoculated with macrophage-tropic SIVmac were tested for neutralization/enhancement of macrophage-tropic SIVmac239-17EBR in normal rhesus macrophages. The plasma of a macaque (R71) that developed a highly virulent neuro-tropic (macrophage-tropic) strain of SIVmac in neuro-adaptation studies significantly enhanced infection of SIVmac239-17EBR as well as infection of dual-tropic SIVmac251. Plasma from other macaques that were inoculated with macrophage-tropic virus, neutralized SIVmac239-17EBR. Also, plasma from macaques infected with lymphocyte-tropic SIVmac239 or dual-tropic SIVmac251 neutralized SIVmac251 infection. When the effect of R71 plasma on the early stages of the SIV life cycle was investigated, this plasma significantly increased binding of 35S-methionine labeled SIVmac239-17EBR and increased binding of 35S-SIVmac251 to primary macrophages, unlike plasma from other macaques infected with either macrophage-tropic or lymphocyte-tropic SIV. A single-cycle infection assay showed higher percentages of positive cells and more intense fluorescence in cultures treated with R71 plasma compared with control plasma. By in situ hybridization, SIV RNA transcripts were detected earlier (12 hr post-infection) and in higher percentages, in cultures treated with R71 plasma than in cultures treated with control plasma (18 hr post-infection). These results indicate that enhancing activity in infected macaque plasma may be associated with severe infection by highly virulent macrophage-tropic (neuro-tropic) SIV. The enhancing effect occurs early in infection and results in increased transcription of SIV RNA.

Animals↗