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Biomedical subjects

K Liu

Publications and source records attributed to K Liu.

At least 379 records · Page 21Linked to original sources
PubMed1995

[Experimental study of radioimmunotherapy for xenograft of human esophageal carcinoma].

Using nude mice bearing human esophageal carcinoma strain Eca 109 as models of tumor, we tested the therapeutic efficiency of 131I labelled monoclonal antibody MGb2 A 4-week experimental study was carried out in 5 treatment groups: group A, buffer, group B, unlabelled MGb2; group C, 131I-labelled normal mice IgG and group D, 131I-labelled MGb2 18.5MBq. All nude mice above were given agents intraperitoneally. In group E, the animals were given 131I-labelled MGb2 18.5MBq by intratumoral administration. The results showed that from the second week, in group D and E the tumor volume was remarkably decreased as compared with that of the other 3 groups (P < 0.01 or P < 0.05). In the fourth week the mean volume in group D and E were 0.55 cm3 and 0.23cm3, while in group A, the volume was 1.43cm3. The inhibition rate of tumor growth in group D and E was higher than in other groups from the second week (P < 0.01), especialy in the third and fourth week with a mean value of 62. 4%, 61.5% and 82.2%, 83.9% respectively. There were no significant differences between group A, B, and C in tumor volume or growth inhibition rate.

Animals↗
PubMed1995

[Growth pattern and metastatic behaviour of orthotopically metastatic model of human hepatocellular carcinoma in nude mice].

Growth pattern, metastatic behaviour and serial alph-a-fetoprotein (AFP) level of highly metastatic model of human hepatocellular carcinoma in nude mice (LCI-D20), which constructed by using orthotopic implantation of histologically intact patient specimens, were studied by implanting into the liver, subcutis and peritoneum of nude mice. Pathologic (by light and electronmicroscopic examination) and biologic (chromosome karyotype and DNA contents by flow cytometry) characteristics of LCI-D20 were also observed. The results showed that transplantability of LCI-D20 was 100% in 12 generations (passage time: 20 days) and all of these mice implanted tumors died within 40 days after transplantation due to serious metastasis. After LCI-D20 implanted into the liver of nude mice, growing implant-tumors in progress were negatively related to their double time during animal survival. LCI-D20 maintained 100% (70/70) metastatic rate in nude mice that showed early intrahepatic metastasis and late lymphatic and pulmonary metastasis. The high metastatic potentials of LCI-D20 tumor cells were kept in subcutis and peritoneum (70%, 100% respectively). The increase of the serial AFP secreting from the tumor cells was correlated with the implantation tumor growth rate (797.5 micrograms/L/5th week). The data from histological and electronmicroscopic findings, chromosome karyotype and DNA content analysis of the tumor cells revealed characteristics of human hepatocellular carcinoma. The results indicated that LCI-D20 exhibited the variety of clinical behaviours seen in hepatoma patients and it could be a useful model for investigating the metastasis mechanism of human hepatoma and anti-metastasis therapy.

Adult↗
PubMed1995

[The relation between p53 mutations and tumor invasiveness of human hepatocellular carcinoma].

We have combined the polymerase chain reaction (PCR) with the HaeIII enzyme restriction analysis to study the mutations at codon 249 of p53 gene in L02 human liver cell line, Bel-7402, SMMC-7721 human hepatocellular carcinoma cell lines and 19 surgical specimens of hepatocellular carcinoma (HCC) and their surrounding non-cancer liver tissues. None of the three cell lines and the non-cancer liver tissues was found to have p53 mutation; but 10 of 19 HCC samples (52.6%) had p53 point mutations, and the p53 gene mutated more frequently in HCC with incomplete capsule, intrahepatic metastasis, or multiple nodules than in those with well encapsulated (70% vs 33.3%, P < 0.05), no intrahepatic metastasis (71.4% vs 41.6%, P < 0.05) and single nodule (83.3% vs 38.5%, P < 0.05). These suggested that the codon 249 was a mutational hotspot of the p53 gene in human HCC seen in China, and p53 mutations may be related to invasiveness of human HCC.

Base Sequence↗
PubMed1995

Opioid in peripheral analgesia: intra-articular morphine for pain control after arthroscopic knee surgery.

BACKGROUND: Some authors reported that a small dose of intra-articular morphine (1-5 mg) injection provided a potent and long-acting analgesic effect on pain after arthroscopic knee surgery. However, many in other reports did not agree to this result. Therefore, the characteristic of the analgesic effect of intra-articular morphine is worth evaluation. In order to rule out the systemic action of intra-articular morphine, we designed a study to compare the efficacy of 3 mg intra-articular morphine with that of 3 mg intravenous morphine in providing analgesia after arthroscopic knee surgery. METHODS: Sixty patients undergoing arthroscopic knee surgery under spinal anesthesia were randomly divided into two groups (n = 30, each). At the end of surgery, group 1 received 3 mg intra-articular morphine in 15 ml isotonic saline and intravenous isotonic saline 10 ml; group 2 received 15 ml intra-articular isotonic saline and 3 mg intravenous morphine in 10 ml isotonic saline. Postoperative pain was evaluated using visual analogue scale (VAS) during an active or passive flexion of the operated knee joint. Also, additional analgesic consumption requested by patient postoperatively (morphine, 2 mg, iv, each) was recorded. RESULTS: Pain scores were lower in group 1 than in group 2 from 4 to 36 h postoperatively (Mann-Whitney rank-sum test). Also, the consumption of supplemental analgesic morphine was lower in group 1 than in group 2 from 6 to 36 h postoperatively. CONCLUSIONS: Intra-articular morphine (3 mg) provided long-lasting analgesia from 6 to 36 h postoperatively and this effect was not due to systemic absorption of morphine.

Adult↗
PubMed1995

[The effect of anti basic fibroblast growth factor on the development of experimental silicosis bacillus].

Anti-bFGF serum was used to treat rabbit experimental silicosis. At 90 days, when experimental group was compared with control group, the number and size of the nodules in experimental group were much less and smaller than those in control group. Nodules in control group were mainly consist of fibroblast mixed with a small amount of collagen fiber, whereas nodules in experimental group were made up of macrophages. At 180 days, in addition to fibroblasts, there was II to III degree of collagen fiber in nodules of control group. Most of nodules in experimental group mainly contained macrophages. Fibroblasts of lung in fetal mice were cultured in vitro. The results showed that bFGF stimulated proliferation of fibroblast, whereas anti-bFGF serum inhibited fibroblast growth. It appeared that anti-bFGF serum actually blocked proliferation of fibroblast and fibrosis in rabbit experimental silicosis.

Animals↗
PubMed1994

On the origin of mRNA encoding the truncated dopamine D3-type receptor D3nf and detection of D3nf-like immunoreactivity in human brain.

A truncated dopamine D3-receptor-like mRNA, named D3nf, predicts a protein that differs from the D3-receptor only in the carboxyl terminus. However, such a protein has lost the predicted membrane topology typically found for G protein-coupled receptors. Results presented here show that D3nf mRNA arises from the D3-encoded primary transcript via alternative splicing. This splicing, however, appears to involve cleavage of an unusual 3' splice site. Therefore, we tested the possibility that D3nf mRNA results from a splicing error. If this were the case, D3nf mRNA would be expected to be present in the cytoplasm only at very low amounts, and it would not be expected to be translated into protein. However, the relative abundance of cytoplasmic D3/D3nf mRNA in human cortical tissues was found to be similar. Furthermore, we raised polyclonal antisera against the predicted carboxyl-terminal peptide sequence of D3nf that reacts specifically with a protein expressed in stably D3nf mRNA-expressing COS 7 cells. The use of this antiserum also revealed the presence of a approximately 68 kDa D3nf-like immunoreactive protein in human brain, suggesting that the atypically processed D3nf mRNA is translated.

Aged↗
PubMed1994

Generation of thiyl and ascorbyl radicals in the reaction of peroxynitrite with thiols and ascorbate at physiological pH.

Electron spin resonance (ESR) spin trapping was utilized to investigate the reaction of peroxynitrite with thiols and ascorbate at physiological pH. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The reaction of peroxynitrite with DMPO generated 5,5-dimethylpyrrolidone-(2)-oxy-(1) (DMPOX). Formate enhanced the peroxynitrite decomposition but did not generate any detectable amount of formate-derived free radicals. Thus, the spin trapping measurements provided no evidence for hydroxyl (.OH) radical generation in peroxynitrite decomposition at physiological pH. Thiols (glutathione, cysteine, and penicillamine) and ascorbate reacted with peroxynitrite to generate the corresponding thiyl and ascorbyl radicals. The one-electron oxidation of thiols by peroxynitrite may be one of the important mechanisms for peroxynitrite-induced toxicity and ascorbate may provide a detoxification pathway.

Ascorbic Acid↗
PubMed1994

Characterization of the mouse Rep-3 gene: sequence similarities to bacterial and yeast mismatch-repair proteins.

The mouse Rep-3 gene is transcribed divergently from the same promoter region as the dihydrofolate reductase-encoding gene and has a deduced amino-acid sequence that shares identity with the bacterial protein, MutS, which is involved in DNA mismatch repair. We have cloned Rep-3, mapped it and sequenced all of the known exons and their intron junction sequences. We find that the open reading frame is considerably larger than initially reported and that the most abundant form of Rep-3 mRNA encodes a protein of 123 kDa. The gene spans at least 134 kb and consists of 26 exons, including several alternatively spliced exons. All of the exon/intron junctions match the expected consensus sequences with the exception of the splice junctions for intron 6, which has AT and AC dinucleotides instead of the usual GT and AG bordering the exon sequences. The junction sequences for this intron share consensus sequences with three intron sequences from other genes, thereby helping to establish an alternative consensus sequence.

Amino Acid Sequence↗
PubMed1994

Lidocaine protects hippocampal neurons against ischemic damage by preventing increase of extracellular excitatory amino acids: a microdialysis study in Mongolian gerbils.

Extracellular levels of amino acids in the hippocampal CA1 region of the gerbil were analyzed by a microdialysis-HPLC procedure. Transient forebrain ischemia produced significant increase in aspartate, glutamate, glycine and taurine (760%, 1070%, 190% and 1210%, respectively), and neuronal blockade by perfusion with a lidocaine (4 mM)-containing medium resulted in 67%, 79%, 58% and 59% reduction in the peak values of each amino acid, respectively. On the other hand, an intracerebroventricular administration of lidocaine, 0.8 mumol or more, produced a protective effect against delayed damage of hippocampal CA1 pyramidal cells, which was caused by bilateral carotid artery occlusion for 4 min. The results suggest that lidocaine may protect neurons against ischemic damage, by preventing the ischemia-induced rise of extracellular concentration of excitatory amino acid.

Animals↗
PubMed1994

One-electron reduction of vanadate by ascorbate and related free radical generation at physiological pH.

The one-electron reduction of vanadate (vanadium(V)) by ascorbate and related free radical generation at physiological pH was investigated by ESR and ESR spin trapping. The spin trap used was 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Incubation of vanadium(V) with ascorbate generated significant amounts of vanadium(IV) in phosphate buffer (pH 7.4) but not in sodium cacodylate buffer (pH 7.4) nor in water. The vanadium(IV) yield increased with increasing ascorbate concentration, reaching a maximum at a vanadium(V): ascorbate ratio of 2:1. Addition of formate to the incubation mixture containing vanadium(V), ascorbate, and phosphate generated carboxylate radical (.COO-), indicating the formation of reactive species in the vanadium(V) reduction mechanism. In the presence of H2O2 a mixture of vanadium(V), ascorbate, and phosphate buffer generated hydroxyl radical (.OH) via a Fenton-like reaction (vanadium(IV)+H2O2-->vanadium(V)+.OH+OH-). The .OH yield was favored at relatively low ascorbate concentrations. Omission of phosphate sharply reduced the .OH yield. The vanadium(IV) generated by ascorbate reduction of vanadium(V) in the presence of phosphate was also capable of generating lipid hydroperoxide-derived free radicals from cumene hydroperoxide, a model lipid hydroperoxide. Because of the ubiquitous presence of ascorbate in cellular system at relatively high concentrations, one-electron reduction of vanadium(V) by ascorbate together with phosphate may represent an important vanadium(V) reduction pathway in vivo. The resulting reactive species generated by vanadium(IV) from H2O2 and lipid hydroperoxide via a Fenton-like reaction may play a significant role in the mechanism of vanadium(V)-induced cellular injury.

Ascorbic Acid↗
PubMed1994

Hypocholesterolemic effects of mixture Da Huai on experimental rats and treatment of a homozygous FH child.

This study observes the hypocholesterolemic effects of Mixture Da Huai--a drug of enhancing monocyte macrophage system--on experimental rats, and the treatment of a homozygous familial hypercholesterolemia (FH) child. The results show that TC, VLDL-C and LDL-C in Mixture Da Huai group were significantly reduced and HDL-C was significantly increased. Fractional clearance rates for 125I-GLC-LDL, and the 125I-GLD-LDL uptake of rat peritoneal macrophages were significantly increased. Excretions of total sterol and acidic sterol in feces were also increased. After treatment for 3 months, serum TC and LDL-C of a homozygous FH child were significantly decreased. Tendon and cutaneous xanthomas were limited. This study indicates that by promoting the monocyte macrophage system to degrade LDL, a promising prevention and treatment of hypercholesterolemia and atherosclerosis might be provided, especially in the treatment of homozygous FH.

Animals↗
PubMed1994

Ethnic differences in electrocardiographic left ventricular hypertrophy in young and middle-aged employed American men.

In the United States population, black men have higher prevalence rates of electrocardiographic (ECG) high QRS voltage, more ST-segment and T-wave abnormalities, and more ECG left ventricular hypertrophy (LVH) than do white men. Reasons for these differences have not been fully elucidated. The prevalence rate of ECG LVH and associated characteristics were compared in black and white men in the Chicago Heart Association Detection Project in Industry population study. Data were from 1,391 black men and 19,126 white men (age range 20 to 64 years) employed by 84 Chicago organizations. ECG LVH was defined by the presence of both high QRS (Minnesota code 3.3) and ST-T abnormality (code 4.1-4.3 or 5.1-5.3). Black men had a significantly higher prevalence rate of ECG LVH than did white men in each 15-year age group (15.9 vs 2.4, 14.6 vs 2.8, and 35.7 vs 12.5/1,000 in the 20- to 34-, 35- to 49-, and 50-to 64-year age groups, respectively; p < 0.01 for each comparison). Multiple logistic regression analyses indicated that systolic blood pressure and age were associated positively with ECG LVH (p < 0.01) in both black and white men. Men with history of hypertension and receiving drug treatment had a greater likelihood of having ECG LVH than did those with history of hypertension but not receiving drug treatment, possibly because those with more severe hypertension were more likely to have been prescribed medication. Serum cholesterol, cigarettes smoked/day, 1-hour post-load plasma glucose and education were not consistently related to ECG LVH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Post-irradiation bladder dysfunction: muscle strip findings.

Strips of rat detrusor muscle were studied in an organ bath 6 months after X-irradiation at doses of 15 and 25 Gy; cystometric studies in these animals had shown a persistent and significant reduction in compliance. The organ bath study demonstrated an increase in the purinergic sensitivity of irradiated detrusor muscle as compared with control. This was significant: p < 0.0145 for the 25 Gy dose group (n = 8) and p < 0.0456 for the 15 Gy group (n = 8) at an alpha,beta-methylene-ATP concentration of 10(-4) M (Mann-Whitney U-Test). There was no difference in sensitivity to cholinergic or noradrenergic stimulation, or to electrical stimulation of the transmural nerves. The finding of purinergic hypersensitivity in irradiated muscle, coupled with ultrastructural evidence of a neural injury, raises the interesting possibility that a denervation supersensitivity phenomenon may contribute to the pathophysiology of post-irradiation bladder dysfunction.

Animals↗
PubMed1994

An immunohistochemical study of the c-fos protooncogene in the developing human retina.

The localization and distribution of the protooncogene c-fos were studied immunohistochemically in the retina of human fetuses ranging in age from 15 to 40 weeks of gestation. The highest levels of immunoreactivity were observed in the retinae of younger fetuses, decreasing in intensity with increasing age. At 15 weeks of gestation intense immunoreactivity was observed in the inner nuclear layer while the photoreceptor cells exhibited moderate staining. At 26 weeks of gestation, immunoreactivity in the inner nuclear layer was reduced. The ganglion cells, amacrine cells and photoreceptor cells showed moderate immunopositivity throughout the 26-40 weeks period. The role of c-fos in development is discussed in the light of its other known functions.

Embryonic and Fetal Development↗
PubMed1994

Magnetic resonance imaging of rodent tumors using radiofrequency gradient echoes.

This paper evaluates the use of radiofrequency (RF) magnetic field gradient echoes to provide contrast in magnetic resonance (MR) images of model tumors. Decay of RF gradient echoes as a function of evolution time was measured and sensitivity of the decay to changes in blood pressure was evaluated. Previous investigators have demonstrated that static field (B0) gradient echoes provide MR image contrast which is sensitive to the rate of self-diffusion of tissue water and may also be sensitive to the rate of tissue perfusion. Gradient echoes produced by RF magnetic field gradients provide a useful alternative to the conventional B0 methods. Unlike B0 gradient echoes RF gradient echoes are relatively insensitive to local magnetic susceptibility gradients and to magnetic field gradients produced by eddy currents. Differences between the two methods may be particularly significant for studies of tumors where large concentrations of deoxyhemoglobin and other paramagnetic substances may cause significant susceptibility gradients. Mammary adenocarcinomas subcutaneously implanted in the flanks of female Fisher rats were studied. Magnetic resonance experiments were performed at 2 T. A surface coil was used to provide an RF gradient and to excite and detect signals from the tumors. The decay of echo amplitude as a function of evolution time was measured and the decay at short and long evolution times was analyzed independently to calculate two apparent diffusion coefficients (ADCs). The preparation was extremely stable and the standard error for 10 consecutive measurements of gradient echo amplitude made over 30-60 min with an RF gradient strength of 50 kHz/cm, gradient duration of 1 ms (i.e., 50 cycles/cm), and echo evolution time (td) of 1 s was generally +/- 0.8%. The ADC calculated from the decay at short evolution times was approximately 3 x 10(-5) cm2/s. The ADC calculated from the decay at longer evolution times was approximately 0.5 x 10(-5) cm2/s. Both ADCs decreased immediately following sacrifice and administration of Hydralazine. The experiments demonstrate that measurements of RF gradient echo amplitudes in tumors can be made in vivo with a high degree of reproducibility and suggest that RF gradient echo amplitudes are sensitive to acute physiological changes in tumors. This method may be useful for characterization of tumors and prediction and monitoring of effects of therapeutic agents.

Animals↗
PubMed1994

A comparison of two methods to ascertain dietary intake: the CARDIA Study.

Data on dietary intake were collected in the Coronary Artery Risk Development in Young Adults (CARDIA) Study at the baseline examination in 1985-86 and again at the second examination 2 years later. At baseline, a diet history questionnaire developed for the CARDIA study was used; at the second exam the NCI (Block) food frequency questionnaire was used. The purpose of the present report is to compare the estimated nutrient intakes obtained with the two instruments; to compare correlations of nutrient intakes obtained at the two exams with those observed for other lifestyle and physiological variables also measured 2 years apart; and to assess ability to test hypotheses relating 2-year changes in risk factors to between-exam differences in reported nutrient intakes. Mean levels of reported intake were generally greater for both blacks and whites on the CARDIA diet history than on the Block food frequency. Rank order correlations of reported nutrient intakes between the two questionnaires indicated greater consistency between instruments for whites (r's ranging between 0.35 and 0.52) than for blacks (r's ranging between 0.29 and 0.45). Correlations over time for nutrients were smaller than those observed for body size measures and lipid levels but were similar in magnitude to those for blood pressure, physical activity, and life events. At both exams, total caloric intake was positively associated with physical activity (range of r's for CARDIA were 0.07 for white women to 0.23 for black men, the range of r's for Block were 0.06 for women to 0.11 for white men). Using data from the two examinations, 2-year changes in total plasma cholesterol were significantly related to 2 year changes in Keys scores. The results of this comparison are useful in that they show similarities and differences between two instruments developed to gather dietary intake data. The study also illustrates the need to monitor young adults during a time when rapid changes occur in many lifestyle and physiologic factors.

Adult↗