Search PubMed⌕ Search

Biomedical subjects

C Y Lu

Publications and source records attributed to C Y Lu.

At least 109 records · Page 6Linked to original sources
PubMed1994

Polyamines mediate coronary transcapillary macromolecular transport in the calcium paradox.

This study addresses the role of polyamines and their rate limiting enzyme, ornithine decarboxylase in regulation of macromolecular transport of two macromolecules, fluorescein and horseradish peroxidase, across coronary capillaries. Rat hearts were isolated and retrogradely perfused through the aorta (Langendorff method), stabilized by 10 min perfusion with Krebs-Henseleit medium containing Ca2+, followed by 5 min perfusion with Krebs-Henseleit medium without Ca2+ and an additional 30 s to 2 min with Krebs-Henseleit medium containing 1 mg/ml horseradish peroxidase. alpha-Difluoromethylornithine, the only known function of which is inhibition of ornithine decarboxylase, and putrescine were added as needed. Perfusion with Krebs-Henseleit medium without Ca2+ caused a two-fold increase in fluorescein transport but a decrease in horseradish peroxidase transport. Reperfusion with Krebs-Henseleit medium caused a four-fold increase in fluorescein transport and a ten-fold increase in horseradish peroxidase positive intraendothelial cell vesicles over control values. alpha-Difluoromethylornithine inhibited these increases and putrescine negated the alpha-difluoromethylornithine effect. Other morphological measures of horseradish peroxidase transport and associated membrane activities including modulation of endothelial cells luminal and abluminal pits were effected in the same manner. Transport of macromolecules through coronary capillaries, over the short term studied, appears to be regulated by the ornithine decarboxylase/polyamine pathway.

Animals↗
PubMed1994

Detection of serum hepatitis B virus using a nested polymerase chain reaction assay.

We described a nested polymerase chain reaction (PCR) assay to detect serum hepatitis B virus (HBV) DNA in patients. We compared the sensitivity of the PCR assay to that of slot-blot hybridization for detecting HBV DNA in serum and found that analysis by PCR provides a > 10(4) fold increase over the slot-blot assay. Most of the HBe Ag-positive patients were positive in PCR, and most of those being anti-HBe-positive were negative with this PCR assay.

Base Sequence↗
PubMed1994

Characterization of C-type natriuretic peptide receptors in human mesangial cells.

Our aim was to examine whether the human glomerulus was a target for C-type natriuretic peptide (CNP) and how A, B and C receptors of natriuretic peptides (ANPR-A, ANPR-B, ANPR-C) were distributed in glomerular mesangial and epithelial cells. CNP stimulated cyclic GMP production in cultured human mesangial and epithelial cells with similar threshold concentrations (1 nM) and maximum effects (basal value x 30 at 1 microM). In contrast, atrial natriuretic peptide (ANP) was only stimulatory in epithelial cells. [125I] CNP bound specifically to mesangial cells with a Kd of 0.47 nM and Bmax of 42 fmol/mg. Equilibrium of binding was obtained after four to five hours at +4 degrees C and nonspecific binding represented 10 to 20% of total binding. HS142-1 (100 micrograms/ml), a specific inhibitor of ANPR-A and ANPR-B, suppressed 90% of CNP-dependent cyclic GMP production whereas it had little effect on [125I]-CNP binding, suggesting that C receptors were largely predominant in mesangial cells. No biological effect of CNP on mesangial cells, including change in basal or angiotensin II-induced contractility and inhibition of basal or serum-dependent proliferation, could be demonstrated. Similar results were obtained with 8-bromo-cyclic GMP and sodium nitroprusside. Intraglomerular localization of ANPR-A, ANPR-B and ANPR-C mRNA was studied using reverse transcriptase-polymerase chain reaction with amplification of their corresponding cDNA by different primers. Amplification products were identified on gel electrophoresis by their predicted sizes and sequencing. ANPR-A, ANPR-B and ANPR-C mRNA were present in epithelial cells whereas only ANPR-B and ANPR-C mRNA were detected in mesangial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed1994

Isolation and characterization of a cDNA clone corresponding to the Rt locus of Petunia hybrida.

We have isolated, via differential screening of a Petunia hybrida petal cDNA library, a cDNA clone that corresponds to the Rt locus which controls the conversion of anthocyanidin-3-glucosides to anthocyanidin-3-rutinosides by the UDP rhamnose: anthocyanidin-3-glucoside rhamnosyltransferase (3RT). The cDNA encodes a 469 amino acid long polypeptide with regions of similarity to the UDP glucose: flavonoid glucosyltransferases (3GT) from barley and maize. Some sequence similarity was also observed with non-plant glycosyltransferases. Two aberrant transcripts are present in most of the rt/rt petunia lines examined. Excision of a transposon from an unstable Rt locus of one petunia line (Tr38) is associated with a change in transcript size back to wild-type. The Rt transcript is most abundant in petals from flowers at an early stage of development and levels decline as the flower matures. Transcripts are also detected in the style and anthers but not in leaf, stem, root, petiole, ovary or sepals. Incubation of leaves in glucose under high light conditions induces the expression of the Rt gene as well as other flavonoid pathway genes. In situ hybridization revealed that the Rt transcript predominantly accumulates in the epidermal cells of the petal, the site of anthocyanin accumulation.

Amino Acid Sequence↗
PubMed1994

Xenotransplantation.

Transplantation of solid organs (heart, lung, liver, and kidney) from swine to humans would solve the current critical shortage of cadaver organs needed by patients with end-stage disease of these organs. In addition, transplantation between distant species (discordant xenografting) will require an understanding of a number of unique immunologic features. Discordant xenografts are rejected within minutes to hours after transplantation. This rejection is due to natural immunity by recipients never before exposed to the xenografts. In some species combinations, this fulminant rejection is due to naturally occurring pre-existing antibodies against the xenograft endothelium. In other species combinations, the xenograft activates the alternative pathway of complement. The swine to human species combination is the most clinically relevant. In this combination, natural human and private antibodies recognize alpha-galactosyl residues of glycoproteins and glycolipids. Potential future therapeutic measures to prevent natural immunity include the genetic engineering of human complement inhibitors into swine cell membranes or genetic "knock out" of the enzymes responsible for placing alpha-galactosyl residues on swine cell surfaces. There are also special considerations in acquired immunity against xenografts. Cytokines and adhesion molecules may not work across species lines. Xenograft antigens may have to be processed by host antigen-presenting cells in order to effectively stimulate the immune system.

Animals↗
PubMed1994

[A preliminary study of BCG adjuvant therapy in oral and maxillofacial malignant melanoma.].

Malignant melanoma is a kind of tumor with higher malignant and lower therapeutic effect.it is demonstrated by experiment that melanoma cells have antigenicity and refer to immunology.BCG is a kind of biologic response modifier(BRM).it is able to promote physical antitumor ability.There were 42 patients with oral and maxillofacial malignant melanoma who received freezing therapy and surgery in this paper.11 cases of them added BCG immunotherapy.The result is that the median survival time of therapy plus BCG group is 4 years,and 3 years,5 years,7 years survival rate are 89%,72% and 32%,over 8 years survival rate is 18%.The median survival time of another group is 2 years,and 3 years,5 years,7 years survival rate are 55%,24% and 12%,over 8 years survival rate is 3%.There is a statistically significant difference between these two groups and BCG group has a longer survival time.This preliminary study demonstrated that BCG adjuvant therapy could decrease recurrence of metastases and increase patients survival time.

English Abstract↗
PubMed1994

[Radioimmunological localization study using 131-iodine radioalbelled monoclone antibody ASC5 against human tongue squamous-cell carcinoma.].

Nude mice carrying human tongue squamous-cell carcinoma xenografts were studied in vivo.McAb ASC5 were purified from ascitic fluid obtained from BALB/c mice pristane-primed prior to being inocualted intraperitoneally with hybridoma cell,using with protein A sepharose CL-4B.Nude mice bearing xenografts were given i.v,injection of McAb labelled with 1311 and 1251.Mice were imaged daily with PHO gamma camera and sacrificed at interval after i.v.injection,weighted and counted.Gamma scanning indicated that there were a larger amount of activity detectable in tumor at 72h after i.v.injection 1311ASC5,then the tumor could be more clearly visualized at 96h and remained strongly position over the 7-day period,with the background activity decreasing.Tumor to non-tumor ratio was more than 2.9.It was secondary best of the antibody uptake at 72h,approximately 9.20+/-1.96%ID/g(mean+/-SD),which compared with isotypical antibody-paired normal mouse IgG,the difference was significant at P<0.05.Results demonstrated that ASC5 is useful in localization diagnosis and management of cancer.

English Abstract↗
PubMed1993

Cloning and expression of cytochrome P450 genes controlling flower colour.

Blue and violet flowers generally contain derivatives of delphinidin; red and pink flowers generally contain derivatives of cyanidin or pelargonidin. Differences in hydroxylation patterns of these three major classes of anthocyanidins are controlled by the cytochrome P450 enzymes flavonoid 3'-hydroxylase and flavonoid 3',5'-hydroxylase. Here we report on the isolation of complementary DNA clones of two different flavonoid 3',5'-hydroxylase genes that are expressed in petunia flowers. Restriction-fragment length polymorphism mapping and complementation of mutant petunia lines showed that the flavonoid 3',5'-hydroxylase genes correspond to the genetic loci Hf1 and Hf2.

Amino Acid Sequence↗
PubMed1993

Glomerular filtration rates in persons evaluated as living-related donors--are our standards too high?

We have retrospectively analyzed the glomerular filtration rate by 125-I iothalamate clearance and creatinine clearance in a group of 661 persons evaluated as potential kidney donors. The average GFR in this population is lower than that reported in previous studies and ranges from 102 +/- 15 and 114 +/- 17 ml/min for males and females age 21-30 to 84 +/- 13 and 79 +/- 15 ml/min for males and females age 51-60. Furthermore, there has been a gradual decrease in GFR in this population from 1970 to 1990 in both the entire population and in those under the age of 40. The cause of this drop is not apparent. These data can be utilized to determine the appropriateness of a potential donor for donation, and may indicate that our current standards are too high.

Adult↗
PubMed1993

N-methyl-D-aspartate receptor excitotoxicity involves activation of polyamine synthesis: protection by alpha-difluoromethylornithine.

We investigated the role of polyamines and their regulatory enzyme ornithine decarboxylase in N-methyl-D-aspartate-induced excitotoxicity in embryonic chick retina. N-Methyl-D-aspartate (200 microM) produced an early increase in ornithine decarboxylase activity, putrescine concentration, and Ca2+ entry, leading to selective neuronal death by 30 min. This response was attenuated by the ornithine decarboxylase inhibitor alpha-difluoromethylornithine and the N-methyl-D-aspartate receptor antagonist 5-aminophosphonovaleric acid. Exogenous putrescine increased intracellular putrescine and spermine levels and reversed neuroprotection by alpha-difluoromethylornithine, but not by 5-aminophosphonovaleric acid. N-Methyl-D-aspartate-receptor stimulation of putrescine/polyamine synthesis mediates abnormal Ca2+ entry and acute excitotoxic neuronal death. Postreceptor inhibition of the ornithine decarboxylase/polyamine cascade by alpha-difluoromethylornithine may provide neuroprotection against N-methyl-D-aspartate-induced excitotoxicity.

Animals↗
PubMed1993

Prevention and treatment of renal allograft rejection: new therapeutic approaches and new insights into established therapies.

Renal transplantation is the preferred treatment modality for patients with ESRD who are good surgical risks and able to comply with chronic immunosuppressive medications. Clinical transplantation has advanced significantly, with most transplant centers reporting 1-yr renal allograft survival rates of better than 80%. Nevertheless, rejection and a progressive loss of allografts over time continue to occur. The immunosuppressive agents currently used may lead to the development of life-threatening infections, malignancies, and advanced atherosclerosis as a consequence of some of their side effects. This review examines the mechanisms involved in allograft rejection as currently understood. The recent knowledge into the mechanism of action of cyclosporine, FK506, and rapamycin on T cell activation is presented. Information recently available on some of the established therapies such as steroids, antimetabolites and monoclonal antibodies as well as the newer agents is also discussed. The interaction between clinical transplantation and basic research in immunology continues to result in exciting advances in both fields.

Animals↗
PubMed1993

[Treatment of acute myocardial infarction with oral captopril. A randomized, double blind and placebo controlled pilot study].

A randomized, double blind and placebo-controlled pilot study was done on the use of converting enzyme inhibitor captopril in 98 patients in the early stage of acute myocardial infarction (AMI) with the purpose of testing the feasibility and justifiability of a large clinical trial on such therapy. The results of the study were as follows. (1) The randomization in this study was quite satisfactory. The interruption of the treatment protocol for more than 24 hours and the patients drop out rate were only 5.1% each, and no side effects of captopril were observed. These indicated that such study could be carried out on large scale. (2) Captopril slightly lowered blood pressure (average 10.2/4.5mm Hg after 2 hours of oral 6.25mg) with minimal change of heart rate, but it did not increase the incidence of sustained hypotension. (3) Captopril decreased the angiotensin II level significantly after 2 hours of ingesting 12.5mg. (4) Early captopril treatment tended to reduce the incidence of cardiac free wall rupture, the severity of congestive heart failure and cardiogenic shock, therefore tended to reduce the early mortality of AMI (3/43 captopril group VS 8/55 placebo group).

Angiotensin II↗
PubMed1993

Age-related differences in responses to endotoxin infusion in unanesthetized piglets.

Newborn endotoxic shock syndrome is associated with high morbidity and mortality, yet presents with different clinical manifestations than in older patients. To determine the influence of age on hemodynamic and metabolic responses to endotoxin, we developed a chronically instrumented endotoxic shock model using eight 1-3-day-old and seven 2-3-week-old piglets. Three days after surgery, 10 mg/kg of endotoxin was infused intravenously over 10 min in the younger group, and 5-10 mg/kg was given to the older animals. Two older piglets died immediately after infusion of 5 mg/kg of endotoxin, and five of the seven died within 4 hr, while all eight younger animals lived longer than 4 hr. Pulmonary artery pressure increased significantly after endotoxin in both groups, and there were no differences between groups. Systemic artery pressure and cardiac index fell by 44 +/- 10% and 70 +/- 15%, respectively, 5 min after endotoxin infusion in the older group, while these values did not change significantly in the younger group. Endotoxin infusion also caused greater elevation in pulmonary vascular resistance index in the older animals. In the later phase, which began 30 min after endotoxin, both groups displayed systemic hypotension and pulmonary hypertension, and the groups did not differ from one another in this regard. With progression of endotoxic shock, more severe metabolic acidosis developed in the older animals than in the younger animals. Plasma thromboxane B2 levels in the older group were about double those in younger piglets. Plasma 6-keto-PGF1 alpha and TNF alpha levels in both groups were similar and were significantly increased in the later phase.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗