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Biomedical subjects

L Hou

Publications and source records attributed to L Hou.

At least 55 records · Page 3Linked to original sources
PubMed2000

Hyperbaric oxygen preconditioning induces neuroprotection against ischemia in transient not permanent middle cerebral artery occlusion rat model.

OBJECTIVE: This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia. METHODS: Sixty male SD rats were used in this study. Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model. The rats were randomly allocated to 3 sub-groups: control group (n = 10), HBO-3 group (n = 10), and HBO-5 group (n = 10). The animals in HBO-3 and HBO-5 groups received 1 hour hyperbaric oxygenation at 2.5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively. The animals in the control group received sham treatments. 24 hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique. The neurological outcome was evaluated until 24 hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats. The infarct volume was then assessed by TTC staining. RESULTS: In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group (P < 0.05 and 0.001). The infarct volume decreased from 171.5 +/- 113 mm3 to 40.6 +/- 49.9 mm3(P < 0.05) in the HBO-3 group and 16.2 +/- 28.8 mm3(P < 0.01) in the HBO-5 group. There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats. CONCLUSIONS: The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a "dose-dependent" manner.

Animals↗
PubMed2000

[Expression of telomerase genes in human tumors].

OBJECTIVE: To investigate the correlation between the expression of telomerase genes and malignant phenotypes of human tumors and to compare the expression of telomerase genes and its activity reported in order to evaluate the role of detection of telomerase genes in tumor diagnosis. METHODS: With in situ hybridization, the expression and distribution of telomerase hTR and hTRT genes were observed in 78 cases of human cancer tissues, 20 cases of precancerous lesions and 28 of benign lesions. The results were statistically analyzed. RESULTS: hTR and hTRT were detected in 85% (66/78) and 82% (64/78) of the primary cancers. While in the adjacent tissues, the positive rates were only 3% (2/78) and 5% (4/78). In 20 precancerous cases, the positive rate for hTR and hTRT were 20% (4/20) and 15% (3/20) and the positive cases in 28 benign lesions were 0 and 1/28 (4%), respectively. The positive detection of hTR and hTRT expression in cancer group were significantly different from those in the adjacent tissues, precancerous cases and benign lesion group (P < 0.01). In analysing main types of the human cancers, the positive frequency of hTR and hTRT were 94% (15/16) and 88% (14/16) for the breast cancer, 85% (17/20) and 90% (18/20) for the colon cancer, 80% (8/10) and 80% (8/10) for the gallbladder cancer, 75% (6/8) and 75% (6/8) for the lung cancer, 75% (6/8) and 75% (6/8) for the stomach cancer, and 83% (5/6) and 83% (5/6) for the esophagus cancer, respectively. The expression level of telomerase hTR and hTRT correlated well with the malignancy and metastatic potentials in breast cancer, colon cancer and bladder cancer. Besides, the expressions of hTR and hTRT were noticed to be also highly correlated (P < 0.01). CONCLUSIONS: The expression of telomerase genes correlates with tumor malignant phenotypes, and may reflect the progression of tumors, and the detection of telomerase gene expression may be useful in a retrospective cancer research. It is worthwhile for further study to clarify whether screening of telomerase gene expression is able to become a new index for tumor diagnosis and prognosis.

Breast Neoplasms↗
PubMed2000

[Zymographic analysis of matrix metalloproteinases in mouse carcinoma cell lines with different lymphatic metastasis potential].

OBJECTIVE: To investigate the correlation between lymphatic metastasis and matrix metalloproteinases (MMPs) activity. METHODS: Zymographic analysis was used to detect the difference of MMPs product and activities between high lymphatic metastatic cell line (HCa-F) and low lymphatic metastatic cell line (HCa-P), that were cultured in the medium including homogenate of lymph node or liver or spleen tissue. RESULTS: HCa-F and HCa-P cells produced small quantities of MMP-9 in 1640 medium. After adding lymph node homogenate to the culture medium, F cells produced a large quantity of MMP-9 as well as active MMP-9 and MMP-2. P cells also produced MMP-9, active MMP-9 and MMP-2, but were much lower than that of F cells. Neither F cells nor P cells produced MMPs in the media with homogenate of liver or spleen added. CONCLUSION: The metastatic potential of F cells is stronger than that of P cells may be due to F cell's ability to secrete MMPs is stronger than P cell's, therefore the production of MMPs of hepatocarcinoma cells is closely correlated to their metastatic potential.

Animals↗
PubMed2000

[Selection and recombinant expression of an immunodominant B cell epitope of HIV gp41].

A novel method was designed for disease-specific B cell epitope mapping and epitope expression in E. coli. A phage library displaying random dodecamers was biopanned first with human total IgG antibodies against HIV-1, and then non-specific phages were subtracted by HIV(-) polyclonal antibodies. After three rounds of screening, the positive phages were tested in an ELISA for their reactivity with HIV(+)-IgG and HIV(-)-IgG antibodies. Phages that showed positive reactivity with HIV(+)-IgG, but negative to HIV(-)-IgG, were selected and their displayed peptides were determined by DNA sequencing. All the 13 positive clones sequenced displayed five kinds of peptides (SPKCLGKLLCAF, THQCLGKLQCGV, SCSAKFTCTTQI, KSDCSARFMCSV, DCLKQWACEWSR) that have homology to the HIV-1 gp41(602GCSGKLICTTNV613), demonstrating there is a dominant epitope in the region.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

[Effect of natrahagin, a Chinese cobra venom proteinase on hemorrheology in rat].

The effects of natrahagin, a Chinese cobra venom proteinase on hemorrheology and plasma fibrinogen level in rat was investigated. The results showed that intravenous injection of natrahagin (0.025-0.1 mg/kg) dose-dependently decreased the whole blood viscosity and the plasma viscosity (P < 0.05 or P < 0.01) in rat, but caused no significant effect on hematocrit (P > 0.05). Natrahagin also decreased the plasma fibrinogen level (P < 0.05 or P < 0.01) of rat in a dose-dependent manner at these doses.

Animals↗
PubMed2000

[Morphological and commercial identification on semen torreyae].

The morphological characters and commercial identification on Semen Torreyae has been reported. The results of identification of commercial samples indicated that Torreya grandis was mainly used; T. fargesii, T. yunnanensis and T. jackii were used in their producing areas.

Pharmacognosy↗
PubMed2000

[The preventive effect of the oil from the seed of Torreya grandis cv. merrillii on experimental atherosclerosis in rats].

OBJECTIVE: To determine the preventive effect of the oil from the seed of Torreya grandis cv. merrillii (OTM) on experimental atherosclerosis in rats. METHODS: The concentration of blood lipids, plasma thromboxane (TXA2), prostacyclin (PGI2), the ratio of TXA2/PGI2 and endothelin (ET) were investigated in male Wistar rats fed high-fat feed (HFF) containing OTM(2%) for 12 weeks. RESULTS: OTM could reduce the level of serum total cholesterol (TC), triglyceride (TG) and the atherosclerosic index (AI), and increase the level of serum high-density-lipoprotein cholesterol (HDL-C). The plasma concentration of TXA2, ET and the ratio of TXA2/PGI2 in group supplemented with OTM were lower than those in HFF group. Moreover, the level of plasma PGI2, was higher than that in HFF group. CONCLUSION: OTM is beneficial in preventing atherosclerosis.

Animals↗
PubMed2000

[Application of extended high frequency audiometry in the early diagnosis of noise--induced hearing loss].

OBJECTIVE: To assess the application of 10-20 kHz audiometry in early diagnosis of noise-induced hearing loss and to explore the relationship between hearing loss and subjects' age, the exposure time as well as the noise level. METHODS: One thousand workers with noise exposure history were examined by pure tone audiometry(0.5-20 kHz). One hundred and twenty normal subjects served as the control group. RESULTS: The noise levels at working sites ranged from 95 to 115dB(A). Compared with the control group, noise-exposed subjects showed minor changes in the thresholds from 0.5 to 6 KHz, whereas the thresholds were elevated in the high frequency range of 10-16 kHz (P < 0.001). The incidence of ears without any response to the maximum output at the frequency range of 14 to 20 kHz was much higher (P < 0.01) than that of the control group. In the animals exposed to noise, the thresholds of 10-18 kHz increased with the aging and with increase of working time (6-10 years), but there were no significant differences among subjects exposed to the noises at different levels(P > 0.05). CONCLUSION: In noise-exposed ears, the occurrence of threshold changes in the high frequency range (10 to 20 kHz) is earlier than that in the low frequency range (0.5 to 6 kHz). Aging and working time also affect the 10-20 kHz hearing thresholds. The lack of responses to maximum output and the changes in thresholds in the high frequency range (10-20 kHz) can be used as indices for the diagnosis of early noise-induced hearing loss and for the assessment of the susceptibility of the subject to noise damage.

Adolescent↗
PubMed2000

Molecular cloning of hTRT catalytic domain from HeLa cells and its expression in E. coli and purification.

OBJECTIVE: To investigate the expression of telomerase gene hTRT mRNA in HeLa cells and to obtain hTRT protein for further study. METHODS: The gene for encoding hTRT catalytic domain was cloned based on RT-PCR amplification from HeLa cells and sequenced. The cloned hTRTcDNA was in-frame inserted into His-tag fusion expression vector pEK318. The His-tag hTRT fusion protein were purified by Ni-NTA chromatography and stained by western blotting. RESULTS: An approximately 620bp fragment was generated and cloned into pBluescript SK + between SaII and BamHI sites. DNA sequencing showed the isolated fragment was consistent to those reported. SDS-PAGE present that a 17kDa protein was expressed stably in E. coli JM109 harboring pEKTRT344 containing 6 x His-tag and hTRT 150aa, and the expression level of the protein was about 26% of the total bacterial proteins, while the expression of pEKTRT containing 6 x His-tag and hTRT 243aa was only detectable as 27 kDa band in western blotting. Both of fusion proteins were purified by Ni-NTA chromatography and showed single band( > 95% purifity) in Coomassie Brilliant staininng. Western-blotting confirmed that two proteins could be recognized by the Ni-NTA AP conjugate. CONCLUSIONS: The hTRT catalytic domain was highly conserved. The expressed hTRT protein contained recognizable His-tag, telomerase-specific and strong antigenic epitops, which may be convenient for further investigation.

Catalytic Domain↗
PubMed1999

Optimization of fast acquisition methods for whole-brain relative cerebral blood volume (rCBV) mapping with susceptibility contrast agents.

Fast gradient-echo magnetic resonance scan techniques with spiral and rectilinear (echoplanar) k-space trajectories were optimized to perform bolus-tracking studies of human brain. Cerebral hemodynamics were studied with full brain coverage, a spatial resolution of 4 mm, and a temporal resolution of 2 seconds. The sensitivity of the techniques to detect image signal-intensity changes during the first pass of the contrast agent was studied at a range of TEs using dedicated experiments. For single-shot versions of spiral scanning and echoplanar imaging techniques with a 0.1-mmol/kg injection of gadolinium diethylenetriamine pentaacetic acid using a mechanical injector at 10 mL/sec under 1.5 T, the maximum sensitivity was obtained at TEs between 35 and 45 msec. At TEs less than 35 msec, signal-intensity artifacts were observed in the images. Analysis of the point-spread function revealed that susceptibility changes induced by the contrast agent can result in signal shifts to neighboring voxels. These artifacts are attributed to susceptibility-related signal changes during the acquisition window.

Artifacts↗
PubMed1999

Effects of local tissue environment on the differentiation of neural crest cells in turtle, with special reference to understanding the spatial distribution of pigment cells.

The spatial distribution of neural crest-derived pigment cells in turtles differs markedly from those found in chickens and mice. One hypothesis to explain such differences in the spatial distribution of pigment cells is that local tissue factors interact with neural crest cells, thereby determining their differentiation into pigment-synthesizing cells. It is reported here that local tissue factors in the soft-shell turtle (Trionyx sinensis japonicus) play a critical role in the development of melanophores from neural crest cells during embryogenesis. Undifferentiated neural crest cells derived from trunk neural tubes were co-cultured in vitro with homochronous somites, or with heterochronous dermis, lung or liver for 14 days. Melanophore differentiation from neural crest cells was significantly promoted when co-cultured with cells from lung, somites or dermis, but not when co-cultured with liver cells. These results suggest that local tissue factors stimulate the differentiation of pluripotent neural crest derivatives toward pigment cells. It is proposed that specific environmental cues play an important role in the spatial distribution of pigment cells in a variety of vertebrate species.

Animals↗
PubMed1999

The material basis for reduced mechanical properties in oim mice bones.

Osteogenesis imperfecta (OI), a heritable disease caused by molecular defects in type I collagen, is characterized by skeletal deformities and brittle bones. The heterozygous and homozygous oim mice (oim/+ and oim/oim) exhibit mild and severe OI phenotypes, respectively, serving as controlled animal models of this disease. In the current study, bone geometry, mechanics, and material properties of 1-year-old mice were evaluated to determine factors that influence the severity of phenotype in OI. The oim/oim mice exhibited significantly smaller body size, femur length, and moment of area compared with oim/+ and wild-type (+/+) controls. The oim/oim femur mechanical properties of failure torque and stiffness were 40% and 30%, respectively, of the +/+ values, and 53% and 36% of the oim/+ values. Collagen content was reduced by 20% in the oim/oim compared with +/+ bone and tended to be intermediate to these values for the oim/+. Mineral content was not significantly different between the oim/oim and +/+ bones. However, the oim/oim ash content was significantly reduced compared with that of the oim/+. Mineral carbonate content was reduced by 23% in the oim/oim bone compared with controls. Mineral crystallinity was reduced in the oim/oim and oim/+ bone compared with controls. Overall, for the majority of parameters examined (geometrical, mechanical, and material), the oim/+ values were intermediate to those of the oim/oim and +/+, a finding that parallels the phenotypes of the mice. This provides evidence that specific material properties, such as mineral crystallinity and collagen content, are indicative and possibly predictive of bone fragility in this mouse model, and by analogy in human OI.

Animals↗
PubMed1999

[The action of proglumide blocking gastrin on gastric cancer cells].

OBJECTIVE: To investigate the practicability of proglumide to treat gastric cancer. METHODS: MKN45 gastric cancer cell line was cultured and the effects on gastrin and gastrin receptor antagonist proglumide proliferative rate, cell dynamic cycle distribution and the concentration of cAMP in the cells were observed in vitro. RESULTS: Gastrin promoted the proliferation of MKN45 cells and shifted cells from phase G(0)/G(1) to phase S, G(2)/M as well as increased intracellular cAMP, while proglumide blocked these effects. CONCLUSIONS: Gastrin induces the proliferation and synthesis of DNA by its receptor. Proglumide may provide a new approach of non-cytotoxic treatment of gastric cancer.

Cell Cycle↗
PubMed1999

[Molecular cloning of hTRT catalytic domain and its expression in tumors].

OBJECTIVE: To study the expression of hTRT gene in tumors and its significance in cancer diagnosis. METHODS: The expression of hTRT in HeLa cells and PG cells was estimated by RT-PCR and the hTRT cDNA encoding the catalytic domain from HeLa cells were cloned and sequenced. Using in situ hybridization (ISH) techniques, the expression of hTRT mRNA in 54 human tumors were observed and compared with the expression of hTR. RESULTS: hTRT was detected in both HeLa and PG cells. Sequencing showed that the cloned hTRT catalytic domain cDNA was identical with that reported in the literature. hTRT and hTR expressions were detected in 38/46 and 40/46 malignant tumors respectively, while both hTRT and hTR were not detected in 8 benign tumors. CONCLUSION: hTRT was detected in both HeLa and PG cancer cells. hTRT catalytic domains were highly conservative. The expression of hTRT and hTR were both high in malignant tumors and they were strongly correlated. Our results suggest that detection of hTRT was valuable to clinical oncology diagnosis.

Catalytic Domain↗
PubMed1999

[Effects of p21WAF1/CIP1 gene introduction on a human lung cancer cell line with p53 mutation].

OBJECTIVE: To study the effects of p21WAF1/CIP1 gene expression on the biological hehavior of cancer cells with p53 gene mutation. METHODS: Expression of p21 vehicle was constructed and introduced into a human lung cancer cell ling PG with p53 gene mutation, the morphological and growth characteristics of the transfectant were then analysed. The CDK4 and PCNA levels were evaluated and the response to genotoxic agents were observed. RESULTS: The PG cells with mutant p53 were transfected with ectopic p21 gene which resulted in overexpression of p21 (6-fold of the control). The transfectants presented decreased nuclear irregularity and thinner membrane in nuclear atypia, with delayed growth rate and contact growth inhibition. The transfectant also displayed high serum requirement in culture and increased anchorage dependence. Both levels of CDK4 and PCNA were decreased. However, the cisplatin induced cell apoptosis was delayed. CONCLUSIONS: Expression of p21WAF1/CIP1 gene was effective in cancer suppression even in p53 gene mutation. This may have been achieved through lowering of CDK4 or PCNA levels and not involving the apoptosis mechanism. Activation of p21WAF1/CIP1 gene may be considered a bypass for restoration of p53 gene function in cancer cells with p53 gene mutation.

Antineoplastic Agents↗
PubMed1999

[Expression of antisense telomerase genes suppressing human cancer malignant phenotypes].

OBJECTIVE: Altering the expression of telomerase genes hTRT and hTR to induce changes in cancer cell biology and to determine their value in cancer gene therapy. METHODS: By genetic transfection of antisense hTRT into HeLa cells, and treatment of PG cells with antisenes hTR oligonucleotides, their effects on cancer cell growth and malignant phenotypes were analyzed. RESULTS: The vehicle for eukaryotic expression of hTRT antisense was constructed and transfected into HeLa cells. The obtained transfectants T4, T5 that could produce antisense hTRT stablely showed marked decrease in growth, with an arrest rate of 24%; the presence of contact growth inhibition was obvious; in nude mice transplantation, the rate for tumor induction was decreased from 100% to 25% or 0%; histologically, the tumor cells from inoculation of transfectant showed less nuclear chromatins and fewer giant tumor cells than those of the parent HeLa cells;the expression of PCNA was significantly reduced in the transfected cells. Treatment of antisense hTR oligonucleotides inhibited PG cell growth at a rate of 8%. CONCLUSIONS: Antisense expression of telomerase genes could significantly suppress cancer cell growth, decrease malignant phenotypes and histological atypia. Therefore, altering expression of telomerase genes may be a new pathway for cancer therapy.

Animals↗