Biomedical subjects

R Lu

Publications and source records attributed to R Lu.

At least 55 records · Page 3Linked to original sources

PubMed2000

[The histological changes after preserved human amniotic membrane transplantation for conjunctival reconstruction of rabbits eyes].

PURPOSE: To investigate the histological changes after preserved human amnotic membrane transplantation of rabbit eyes. METHODS: The conjunctiva of 12 New Zealand albino rabbits' right eyes were excised partly. Then the preserved human amniotic membrane were transplanted on the sclera. Eyes were enucleated at 1 week, 3 weeks, 5 weeks and 12 weeks (n = 3 for each) after surgery, and they were examined histologically with staining of HE, PAS, and transmission electronic microscopy. RESULTS: At 1 week after transplantation, the human amniotic membrane firmly attached on the sclera, with the dead epithelial cells remaining on its surface. At 3 weeks, conjunctival epithelization was completed on the human amniotic membrane. Abundant PAS-positive goblet cells were recognized. The amnion began resolve. At 12 weeks, the amnion dissolved. On transmission electronic microscopy, the cell polarity is prominent. The epithelial cells contained a large number of mitochondria and endoplasmic reticulum. Microvilli were pronounced on the apical cell membrane. There are many intracellular desmosomes and hemidesmosomes. CONCLUSION: Preserved human amniotic membrane is a valuable conjunctival replacement material. After transplantation, the histology of new tissue is as same as normal conjunctive.

Amnion↗

PubMed2000

[The culture and cryopreservation of human conjunctival epithelium in vitro].

PURPOSES: To detect the best method of culture and preservation of human conjunctival epithelia. METHODS: Human conjunctival epithelia were cultured by tissue inoculation, mechanical separation or enzyme digestion with 0.25% trypsin. The cultured cells were identified through their morphology, growing features and immunohistochemical staining. The third and fourth passage confluent cells were frozen in liquid nitrogen, and resuscitated 30 days later. RESULTS: Cells from tissue digested with 0.25% Trypsin grew much better than those from tissue inoculation. No cell outgrew in mechanical separating group. The cultured cells spread along the flask in polygonal shape and positive in pan-Keratin staining. Ninty percent of the cryopreserved cells were successfully resuscitated. CONCLUSION: Tissue digestion with trypsin is the best approach to culture human conjunctival epithelium, and the cultured cells can be cryopreserved in liquid nitrogen.

Cell Culture Techniques↗

PubMed2000

[A reappraisal of hyperbaric oxygenation effect and study on serum malondialdehyde and superoxide dismutase in patients with sudden deafness].

OBJECTIVE: To reappraise the effect of HBO and to observe the changes of malondialdehyde (MDA) and superoxide dismutase (SOD) in serum of the patients with sudden deafness. METHODS: 60 patients were randomly divided into two groups. One was treated with HBO combined with medical treatment (treatment group). The other was only treated with HBO (control group). There were 30 healthy volunteers as health group. RESULTS: After treatment, there was a significant difference (chi 2 = 6.48, P < 0.05) in patient's groups in hearing examination. After treatment, SOD volume in treatment group had significant difference with health group and control group (t = 23.27, P < 0.01; t = 27.17, P < 0.01) respectively. There was a significant difference of SOD volume in treatment group itself before and after treatment course (t = 29.27, P < 0.01). There was no significant difference of SOD volume in control group itself before and after treatment(t = 1.33, P > 0.05). MDA: There was a significant difference between treatment group and control one after the treatment. There was a significant difference (t = 7.28, P < 0.01) in treatment group before and after treatment course. There was not a significant difference (t = 1.24, P > 0.05) between treatment and health group after the treatment course. There was a significant difference (t = 7.09, P < 0.01) between control group and health one after the treatment course. CONCLUSION: There was no satisfied curative effect on sudden deafness with HBO only.

Adult↗

PubMed1999

Evidence for calcitonin gene-related peptide-mediated ischemic preconditioning in the rat heart.

Previous studies have suggested that calcitonin gene-related peptide (CGRP) may play an important role in the mediation of ischemic preconditioning. In the present study, we examined the release of CGRP during ischemic preconditioning and the effect of preconditioning frequency on this effect in the isolated rat heart. Thirty minutes of global ischemia and 40 min of reperfusion caused a significant cardiac dysfunction and an increase in the release of creatine kinase (CK) during reperfusion. Preconditioning with one, two or three cycles of 5-min ischemia and 5-min reperfusion caused a marked improvement of cardiac function and a decrease in the release of CK, and there was no difference in the degree of improvement among groups. The protective effects of ischemic preconditioning were abolished by the CGRP receptor antagonist CGRP(8-37). A single preconditioning cycle induced a significant increase in the release of CGRP in the coronary effluent. In the hearts treated with two or three preconditioning cycles, the level of CGRP was highest in the first cycle, and was gradually decreased with increasing number of cycles of preconditioning. These results suggest that the protective effects of ischemic preconditioning are mediated by endogenous CGRP in the isolated rat heart.

Animals↗

PubMed1999

Lithium attenuates p53 levels in human neuroblastoma SH-SY5Y cells.

Lithium has neuroprotective effects in a number of model systems which may contribute to the therapeutic effects of lithium in mood disorders. Because the tumor suppressor p53 is linked to cell death, we tested whether lithium administration to human neuroblastoma SH-SY5Y cells modulated the activation of p53. After treatment of cells with H7 (25, 50, and 75 microM), nuclear p53 levels were increased to 464, 816 and 1079% of basal levels, respectively. A 24 h pretreatment with 5 mM lithium reduced these increases by 69, 61 and 28%, respectively. Pretreatment with 2 mM lithium for 1 or 14 days reduced the 25 microM H7-induced elevations of nuclear p53 by 40 and 70%, respectively, and even a 14-day pretreatment with 1 mM lithium caused a significant 16% reduction. Since increased nuclear p53 is a critical intermediate step in many signaling processes that culminate in cell death, attenuation of p53 activation by lithium reveals a mechanism by which lithium may support neuronal survival.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1999

Stimulation of PC cell-derived growth factor (epithelin/granulin precursor) expression by estradiol in human breast cancer cells.

PC cell-derived growth factor (PCDGF) is an 88 kDa glycosylated protein isolated from a highly tumorigenic mouse teratoma derived cell line which is similar to the epithelin/granulin precursor. Using Northern blot and western blot analyses, we detect the expression of PCDGF mRNA and protein in MCF-7 human breast cancer cells. We show that 17-beta-estradiol stimulates PCDGF mRNA and protein expression in a time and dose-dependent manner. The stimulation of PCDGF expression by 17-beta-estradiol was observed as early as 4 hours and reached a maximum at 12 hours. Maximal stimulation of PCDGF mRNA and protein expression by 17-beta-estradiol was observed at a concentration of 10(-8) M. The stimulation of PCDGF expression by 17-beta-estradiol was completely inhibited by treatment with actinomycin D and with the antiestrogen 4-hydroxytamoxifen. The stimulation of PCDGF expression was also demonstrated in another human estrogen-responsive cell line T47D. The results presented here provide evidence of a novel estradiol responsive gene product in human breast cancer cell lines and give information about the hormonal control of epithelin/granulin (PCDGF) expression in these cells.

Blotting, Western↗

PubMed1999

Resveratrol, a natural product derived from grape, exhibits antiestrogenic activity and inhibits the growth of human breast cancer cells.

Resveratrol is a natural phytoalexin compound found in grapes and other food products. In this study, the effect of resveratrol on the growth of human breast cancer cells was examined. Results show that resveratrol inhibits the growth of estrogen receptor(ER)-positive MCF-7 cells in a dose-dependent fashion. Detailed studies with MCF-7 cells demonstrate that resveratrol antagonized the growth-promoting effect of 17-beta-estradiol (E2) in a dose-dependent fashion at both the cellular (cell growth) and the molecular (gene activation) levels. At 5 x 10(-6) M, resveratrol abolished the growth-stimulatory effect mediated by concentrations of E2 up to 10(-9) M. The antiestrogenic effect of resveratrol could be observed at a concentration of 10(-6) M and above. The antiestrogenic effect of resveratrol was also demonstrated at the molecular level. Resveratrol in a dose-dependent fashion antagonized the stimulation by E2 of progesterone receptor gene expression in MCF-7 cells. Moreover, expression of transforming growth factor-alpha and insulin-like growth factor I receptor mRNA was inhibited while the expression of transforming growth factor beta2 mRNA was significantly elevated in MCF-7 cells cultivated in the presence of resveratrol (10(-5) M). In summary, our results show that resveratrol, a partial ER agonist itself, acts as an ER antagonist in the presence of estrogen leading to inhibition of human breast cancer cells.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Protection of calcitonin gene-related peptide-mediated preconditioning against coronary endothelial dysfunction induced by reperfusion in the isolated rat heart.

This study was designed to explore the protective effect of ischemic preconditioning on reperfusion-induced coronary endothelial dysfunction, with a focus on the role of calcitonin gene-related peptide (CGRP) in this effect, in the isolated perfused rat heart. Thirty minutes of global ischemia and 30 min of reperfusion significantly decreased heart rate, left ventricular pressure, and its first derivative and impaired vasodilator responses to acetylcholine. Ischemia-reperfusion did not affect vasodilator responses to sodium nitroprusside. Preconditioning induced by three cycles of 5 min of ischemia and 5 min of reperfusion produced a significant improvement in cardiac function concomitantly with an amelioration of vasodilator responses to acetylcholine. The protective effects of ischemic preconditioning were abolished by CGRP(8-37) (10(-7) M) , the selective CGRP receptor antagonist. After pretreatment with capsaicin (50 mg x kg(-1), s.c.) to deplete endogenous CGRP, the preconditioning effect was absent. Pretreatment with exogenous CGRP (5 x 10(-9) M) for 5 min induced a preconditioning-like protection. The present study suggests that the cardioprotection of ischemic preconditioning is related to the preservation of the coronary endothelial cell, and that the protective effect of preconditioning is mediated by endogenous CGRP in the isolated perfused rat heart.

Animals↗

PubMed1999

Determinants of phencyclidine potency on the nicotinic acetylcholine receptors from muscle and electric organ.

1. Phencyclidine (PCP) is an inhibitor of the nicotinic acetylcholine receptor (AChR) with characteristics of an open-channel blocker. The location of PCP binding site on the AChR molecule is unknown. 2. PCP inhibits the AChR from electric organ with a higher potency than muscle AChR. To find the molecular basis of this difference, we expressed the two native and six hybrid receptors, and two receptors containing mutated mouse gamma subunits in Xenopus laevis oocytes. The inhibition of ACh-induced current in these receptors by PCP was studied using whole-cell voltage-clamp. All hybrid receptors generated robust ACh-induced currents, while incomplete receptors (gamma-less or delta-less) did not. 3. PCP potency was higher on hybrids containing Torpedo beta and gamma subunits regardless of the alpha and delta subunit origin. A mouse gamma subunit containing the asparagine 6' to the serine mutation in the M2 segment conferred a high sensitivity to PCP. 4. These results support the conclusion that the amino acid residues at the position 6' of the M2 segments contribute to the PCP potency difference between Torpedo and mouse receptors. 5. Another noncompetitive inhibitor of the AChR, the cembranoid eupalmerin acetate (EUAC), also inhibited the electric organ receptor with a somewhat higher potency than muscle AChR. However, the IC50 values for EUAC inhibition of hybrid receptors did not follow the pattern observed for PCP. Therefore, these two inhibitors interact differently with the AChR molecule.

Acetylcholine↗

PubMed1999

Detection of telomerase activity in biopsy samples of colorectal cancer.

BACKGROUND: Telomerase is a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends. The expression of telomerase is thought to be required for cellular immortality and oncogenesis. METHODS: To investigate the role of telomerase in the pathogenesis of colorectal cancer, we analysed telomerase activity in biopsy samples of colorectal cancer and colonic adenomas. Using a polymerase chain reaction-based assay, we examined telomerase activity in 52 samples of colorectal cancer, 12 colonic adenomas and 30 normal colonic mucosa samples obtained by endoscopic biopsy. RESULTS: Telomerase activity was detectable in 88.5% (46/52) of colorectal carcinomas, in 50% (6/12) of colonic adenomas but not in normal colorectal mucosa. There was no correlation between telomerase activity and tumour location, type, size and differentiation (P > 0.05). CONCLUSIONS: It was concluded that telomerase activation plays a role in the evolution of colorectal cancer, and that measurement of telomerase activity in biopsied colorectal mucosa samples may provide information both as a diagnostic marker to detect small numbers of cancer cells, and as a screening method for patients at high risk for colorectal carcinoma.

Adenoma↗

PubMed1999

Oxygen free radicals in interleukin-1beta-induced glycosaminoglycan production by retro-ocular fibroblasts from normal subjects and Graves' ophthalmopathy patients.

Graves' ophthalmopathy (GO) is attributed to an autoimmune process that results in the accumulation in retro-ocular tissue of glycosaminoglycans (GAG) that are in turn responsible for the development of clinical signs and symptoms. Retro-ocular fibroblasts are thought to be the source of GAG production and deposition in GO. In the present study, we investigated interleukin (IL)-1beta-induced oxygen free radical production and the role of oxygen free radicals in IL-1beta-induced GAG production in retro-ocular fibroblasts from both normal subjects and patients with GO. Normal retro-ocular fibroblasts demonstrated no measurable oxygen free radicals whereas GO retro-ocular fibroblasts showed detectable signals by electron paramagnetic resonance (EPR) spectroscopy. IL-1beta increased the free radical production in both cells. Superoxide dismutase (SOD) activity in GO retroocular fibroblasts was higher than that in normal cells. IL-1beta dose- and time-dependently stimulated the SOD activity in both cells, with GO retro-ocular fibroblasts showing less responsiveness. IL-1beta dose-dependently increased [3H]glucosamine incorporation into GAG by both cells. An exogenous oxygen free radical-generating system failed to increase GAG. Scavenging oxygen free radicals by the use of SOD (100 U/mL) and catalase (300 U/mL) partially blocked the IL-1beta-induced GAG production in both cells. These results suggest that stress related oxygen free radicals are present in the retro-ocular tissue in GO and that oxygen free radicals are involved in GAG accumulation induced by cytokine IL-1beta.

Catalase↗

PubMed1999

Cloning of mouse prostaglandin transporter PGT cDNA: species-specific substrate affinities.

We recently identified and/or cloned the PG transporter PGT in the rat (rPGT) (Kanai, N., R. Lu, J. A. Satriano, Y. Bao, A. W. Wolkoff, and V. L. Schuster, Science 268: 866-869, 1995) and the human (hPGT) (Lu, R., and V. L. Schuster, J. Clin. Invest. 98: 1142-1149, 1996). Here we have cloned and expressed the mouse PGT (mPGT) cDNA. The tissue distribution of mPGT mRNA expression is significantly more restricted than that of rPGT and hPGT mRNA. Although the deduced amino acid sequence of mPGT is similar to the rat (91% identity) and human (82% identity) homologues, it has three regions of dissimilarity: amino acids 128-163 and 283-298, and valine 610 and isoleucine 611 (predicted to lie within putative transmembrane span 12). Affinities of hPGT, rPGT, and mPGT for several PG substrates differed, with hPGT having the highest [low Michaelis constant (K(m))] and mPGT the lowest affinity. A chimeric protein, linking the N-terminal domain of mPGT with the C-terminal domain of hPGT, had affinity for PGE2 indistinguishable from that of hPGT, indicating that the C-terminal domain dictates K(m). We mutagenized mouse valine 610 and isoleucine 611 to their corresponding human residues (methionine and glycine, respectively); however, these changes did not convert the inhibition constant of mPGT to that of hPGT. The mouse gene was localized to chromosome 9 in a region syntenic with the region of human chromosome 3 containing the hPGT gene. These studies highlight the species-dependence of tissue expression and function of PGT and lay the groundwork for the use of the mouse as a model system for the study of PGT function.

Amino Acid Sequence↗

PubMed1999

Cloning of the human kidney PAH transporter: narrow substrate specificity and regulation by protein kinase C.

Conserved from fish to mammals, renal proximal tubule organic anion secretion plays an important role in drug and xenobiotic elimination. Studies with the model substrate p-aminohippurate (PAH) have suggested that a basolateral PAH/alpha-ketoglutarate exchanger imports diverse organic substrates into the proximal tubule prior to apical secretion. cDNAs encoding PAH transporters have been cloned recently from rat and flounder. Here we report the cloning of a highly similar human PAH transporter (hPAHT) from human kidney. By Northern blot analysis and EST database searching, hPAHT mRNA was detected in kidney and brain. PCR-based monochromosomal somatic cell hybrid mapping placed the hPAHT gene on chromosome 11. When expressed transiently in vitro, hPAHT catalyzed time-dependent and saturable [3H]PAH uptake (Km of approximately 5 microM). Preincubation with unlabeled alpha-ketoglutaric or with glutaric acid stimulated tracer PAH uptake, and preincubation with unlabeled PAH stimulated tracer alpha-ketoglutarate uptake, results that are consistent with PAH/alpha-ketoglutarate exchange. Several structurally diverse organic anions cis-inhibited PAH uptake. Like rat OAT1 organic anion transporter, hPAHT was inhibited by furosemide, indomethacin, probenecid, and alpha-ketoglutarate. Unlike OAT1, hPAHT was not inhibited by prostaglandins or methotrexate (MTX). Moreover, tracer PGE2 and MTX were not transported, indicating that the substrate specificity for transport by hPAHT is not broad. PAH uptake was inhibited by phorbol 12-myristate 13-acetate (PMA) in a dose- and time-dependent fashion, but not by the inactive 4alpha-phorbol-12,13 didecanoate. PMA-induced inhibition was blocked by staurosporine. Thus the protein kinase C-mediated inhibition of basolateral organic anion entry previously reported in intact tubules is likely due, at least in part, to direct modulation of the PAH/alpha-ketoglutarate exchanger.

Amino Acid Sequence↗

PubMed1999

[The possible role of loss of heterozygosity at APC, MCC and DCC genetic loci in esophageal carcinoma].

OBJECTIVE: To investigate the alterations of APC, MCC and DCC genes in human esophageal carcinoma. METHODS: A total of 46 human esophageal cancer specimens were analyzed for the loss of heterozygosity (LOH) at APC, MCC and DCC genetic loci by means of polymerase chain reaction and restriction fragment length polymorphism. RESULTS: The incidence of LOH was 29.0%(9/31) at APC locus, 33.3%(8/24) at MCC locus, and 32.4%(12/37) at DCC locus, respectively. However, there was no statistically significant correlation between LOH at these three loci with such clinical parameters as pathological types, tumor size, invasiveness, and lymph-node metastasis. CONCLUSION: These data suggest that LOH at APC, MCC and DCC loci in esophageal carcinoma is, to certain extent, a common genetic alteration which might play a role in esophageal carcinogenesis.

Chromosome Mapping↗

PubMed1999

[Staging-syndrome differentiation in treating diabetic foot disorder and its effect on hemodynamic changes of lower extremities with arterial ultrasonic Doppler diagnostic apparatus].

OBJECTIVE: To observe the therapeutic effect of staging-Syndrome Differentiation of TCM in treating the diabetic foot disorder and the corresponding hemodynamic changes in lower extremities. METHODS: Chromatic ultrasonic Doppler diagnostic apparatus (ATL-ULTRAMARK 9 HDI, made in USA) was used to determine the arterial hemodynamic changes and clinical effect on the treatment of diabetic foot disorder in 60 non-insulin dependent diabetes mellitus (NIDDM) patients, among them 30 were treated by staging-Syndrome Differentiation of TCM, and the other 30 as control group treated with 654-2, and the 30 cases of nondiabetic foot disorder as normal control group in comparison. RESULTS: Compared to the normal control, the intravascular diameter, blood flow of both treated groups reduced, maximal and minimal speed of blood flow, and the mean speed were accelerated. Values in dorsal pedis artery had present the most sensitive one. In the comparison between before and after treatment, both treated groups were hemodynamic improvement in the lower extremities' artery, more obviously the dorsal pedis artery, while the comparison between these two groups showed that TCM staging-Syndrome Differentiation had a superior effect on lower extremities' hemodynamics to that of 654-2 group. The comprehensive assessment revealed that the treated groups was also significant different in comparing to that of normal control group (P < 0.05). CONCLUSION: The comprehensive TCM treatment of staging-Syndrome Differentiation as the main therapeutic component was prominently better than that of 654-2 application in the treatment.

Adult↗

PubMed1999

[Origin and progress of myelodysplastic syndrome with hypoplasia].

OBJECTIVE: To study the origin and progress of myelodysplastic syndrome (MDS) with hypoplasia. METHODS: The data of twenty-five cases of hypomyeloplastic MDS diagnosed by our department in the last ten years were analyzed. 17 of the 25 cases were followed up for a long time. RESULTS: (1) The percentage of hypomyeloplastic MDS was 11.4% of the total 219 MDS patients. The median age of the 25 cases was (44.8 +/- 14.7) years. (2) FAB subtype: There were 11 cases of RA and 14 of RAEB. (3) Hypomyeloplastic MDS seems to be a developmental phase in the clinical course in some of the patients and not a special type of MDS. Hyper- and hypo-myeloplasia could be transformed from one to another. The transformation of myelodysplasia could occur either in the same or and different FAB subtype. (4) Seven of the seventeen cases transformed to acute leukemia (41.2%), 6 cases were AML and 1 was ALL. 3 of the 7 cases transformed to hypomyeloplastic leukemia and the remaining 4 transformed to hypermyeloplastic leukemia. (5) The median time from the diagnosis of RAEB to leukemia transformation, was 27 months in 7 cases with hypoplastic RAEB. (6) No relationship was found between therapeutic medicines and development of hypomyeloplastic MDS. CONCLUSION: It is suggested that hypomyeloplastic MDS is probably a developmental phase in the clinical course of MDS, but not a special type.

Adult↗

PubMed1999

[Combined use of rhBMP2/BCB and free periosteum in repairing segmental defects in radii of rabbits].

OBJECTIVE: To study the efficacy of combined use of rhBMP2/BCBand free periosteal graft in repairing segmental bony defects. METHODS: A new grafting material (rhBMP2/BCB) was made by combining recombinant human BMP2 (rhBMP2) and an antigen-free bovine cancellous bone (BCB) as a carrier. rhBMP2/BCB was used alone in conjunction with free periosteal graft to repair a 1.5 cm defect in the radius of the rabbit. The defect-repairing capability for each of the treatment modalities was assessed radiographically, biomechanically, and by densitometry and histological studies. RESULTS: rhBMP2/BCB used alone was capable of healing the defect in large by 16 weeks, with a similar repair process and mechanism seen with RBX. Combined use of rhBMP2/BCB and free periosteal graft was superior in terms of increased amount and quality of the new bone formed at the early stage of the repair process (within 12 weeks) to rhBMP2/BCB used in isolation, with the defect basically healed by 12 weeks. CONCLUSIONS: Both methods are effective in repairing segmental bony defects, with rhBMP2/BCB used in conjunction with free periosteal graft being most preferred, considering the satisfactory osteogenesis, osteoconduction and osteoinduction.

Animals↗

PubMed1999

[The detection of microsatellite instability in carcinoma and adenoma of large bowel and its significance].

OBJECTIVE: To explore the role of microsatellite instability (MSI) in colorectal carcinogenesis and the relationship between MSI, proliferation activity and prognosis. METHODS: PCR-SSLP and immunohistochemistry methods were used to detect MSI and the expression of PCNA in 56 cases of carcinomas, 9 cases of adenomas and 6 cases of adenomas with malignant changes. RESULTS: The total positive rate of MSI were 25/56 cases in colorectal carcinomas. The MSI positive cases were 3/4 in HNPCCs, 22/52 in sporadic colorectal carcinomas, 2/9 in adenomas and 2/6 in adenoma with malignant changes respectively. The PCNA labelling index of MSI positive tumors were significantly lower than that of MSI negative tumors (P < 0.01). The 3 and 5 year survival rates in patients with MSI positive colorectal carcinomas were higher than those of MSI negative tumors. CONCLUSION: MSI may be an early molecular alteration and another molecular mechanism in colorectal carcinogenesis. The MSI positive tumors have low proliferating activity and a better clinical outcome. The detection of MSI might be useful in predicting prognosis of colorectal carcinomas.

Adenoma↗