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Biomedical subjects

H Liu

Publications and source records attributed to H Liu.

At least 1,027 records · Page 57Linked to original sources
PubMed1995

[Studies on the histological classification of proliferative disease of breast and its relation with breast carcinoma].

According to the degree of fibroplastic proliferation, proliferative disease of breast can be divided into three types: lobular hyperplasia type, fibroadenosis type and fibrosclerosis type. Each type could have simple or compound lesions. The latter include: atypical hyperplasia of duct epithelial cells, large sweat gland metaplasia, cyst and fibroadenoma formation. The progress of lesions coincided with the increase of age. The age of fibrosclerosis patients were close to that of patients with breast carcinoma accompanied with proliferative breast disease. The level of PCNA expression in the three types of proliferative breast disease increased progressively and the level of PCNA expression in fibrosclerosis and breast carcinoma being similar. It is emphasized that in the fibrosclerosis type hyperplasia, the presence of twisting, fragmentation or incomplete encirclement of the periductal myoepithelial cells as well as the basement membrane of the tubules may be considered as a warning to call one's attention to follow up patients closely.

Adult↗
PubMed1995

Morphometric evaluation on myocardial protection of cold crystalloid versus warm blood cardioplegia.

Twenty patients undergoing open-heart valve replacement were divided randomly into two groups in this study; intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (hypothermic group) and continuous administration of warm blood cardioplegia with normothermic CPB (normothermic group) respectively. Tissue samples were taken from the right atrium before weaning from CPB and from the right appendage 30 minutes after removal of the cross-clamp. The results of pathological study in these two groups were as follows: the structural alterations were most severe during the ischemic period in the hypothermic group. Damages of the myocardial mitochondria examined with transmission electron microscope were found more severe in the hypothermic group than in the normothermic group, and in the reperfusion period than in the ischemic period. Loss of integrity of the mitochondrial membrane could be noted during reperfusion in the hypothermic group. The surface to volume ratios of mitochondria of each period of the two groups were calculated by computerizing the microphotographs of the myocardium. It was shown that the average of the surface to volume ratios was smallest in the reperfusion period in the normothermic group. It seemed that the volumes of the mitochondria were larger in the warm group than in the cold one. Probably the results were due to more severe damages of the mitochondrial membranes in the hypothermic group, which led to the release of the contents out of the mitochondria while in the normothermic group, the sodium-pump was disordered and it made the mitochondria swell. Pathologically, blood cardioplegic perfusion with the use of normothermic CPB is a feasible method for myocardial protection in open-heart surgery.

Bicarbonates↗
PubMed1995

Crown gall culture and production of tanshinone in Salvia miltiorrhiza.

Crown galls were induced by direct infection of sterile seedlings with Agrobacterium tumefaciens C58, and the transformation was proved by opine identification. The crown galls grew well in a hormone-free medium. B5 and MS basic media were good for the growth of crown galls (strain Ca), which increased up to 102 and 90 times in a month, respectively. However, 67-V and WP basic media are good for tanshinone production. It has been shown that crown galls can be utilized as a culture system to produce secondary metabolites.

Abietanes↗
PubMed1995

Epidermal growth factor in acute promyelocytic leukemia treated with retinoic acid.

We studied 18 patients with acute promyelocytic leukaemia and 13 with relapsed APL. We found a significantly elevated EGF in acute leukaemia, especially in APL, being 418.59 +/- 19.2 micrograms in the 24-h urine that was much higher than that of the normal controls. When eight APL patients achieved complete remission by RA treatment, the EGF value decreased to 149.9 +/- 27.3 micrograms in the 24-h urine near to normal. In 13 patients with relapsed APL, EGF rose to 446.9 +/- 82.6 micrograms in the 24-h urine. Most interestingly, this elevated EGF could be detected before the relapse by 5 +/- 0.84 months in seven out of eight APL with relapse. We suggest that the unaccountably elevated EGF during remission period may be an indicator of the occurrence of relapse.

Acute Disease↗
PubMed1995

Molecular recognition of tRNA(Pro) by Escherichia coli proline-tRNA synthetase.

We have investigated the molecular recognition of tRNA(Pro) by Escherichia coli proline tRNA synthetase (ProRS) in vitro using semi-synthetic tRNAs and site-directed mutagenesis of full-length tRNA transcripts. These studies have led to an improved understanding of how this class II synthetase interacts with its tRNA substrate. The ability to efficiently aminoacylate a tRNA(Pro) molecule assembled by annealing together a shorter, chemically synthesized oligonucleotide and a 3/4 tRNA prepared enzymatically, has facilitated the identification of RNA structural features that are critical for aminoacylation by ProRS. This approach has been successful using either a 3'-3/4 tRNA annealed to a 5'-oligonucleotide or a 5'-3/4 tRNA annealed to a 3'-oligonucleotide. These studies show that ProRS appears to be particularly sensitive to mutations that result in structural changes in the core region of tRNA(Pro). Moreover, the so-called "variable pocket" nucleotides appear to be dispensable for aminoacylation. We have also identified a specific 2'-hydroxyl-base interaction between the ribose of U8 and the 2-amino group of G46 that makes a thermodynamically significant contribution to tRNA(Pro) aminoacylation by E. coli ProRS.

Amino Acyl-tRNA Synthetases↗
PubMed1995

Cloning and overexpression of thermostable DNA polymerase gene in Escherichia coli.

Thermostable DNA polymerase genes had been amplified from Thermus aquaticus YT-1 using the PCR technique. The amplified 2.5-kb DNA fragment was inserted into pUC18 and confirmed to be a thermostable DNA polymerase gene by restriction mapping and DNA sequencing. The insert fragment was then combined into an expression vector, pBV221. This recombinant plasmid overexpressed a 94-kDa of recombinant protein in E. coli. A 100-mL E. coli. culture could yield 1.5 x 10(5) units of Taq DNA polymerase, which could be applied in the PCR.

Base Sequence↗
PubMed1995

[Effects of low dose aspirin on platelet function and prostaglandins metabolism in systemic and coronary circulation in patients with ischemia heart disease].

Eleven patients with ischemia heart disease (IHD) were treated with low dose aspirin (ASA, 50mg/day) for more than two weeks (ASA group). 29 cases with IHD not taking ASA served as patient control (NASA group) and 13 cases without IHD not taking ASA as normal control. Blood samples for measurement of plasma (serum) TXB2 and 6-keto-PGF1 alpha were simultaneously taken from aortic root (AO) and coronary sinus (CS). The results showed: ASA group had lower plasma TXB2 level in AO blood than NASA group (P < 0.05), but there was no significant difference in plasma 6-keto-PGF1 alpha level between the two groups. Both of plasma and serum TXB2/6-keto-PGF1 alpha ratios in AO blood in ASA group were significantly lower than those in NASA group (P < 0.05 and P < 0.0005 respectively). Plasma TXB2 CS/AO ratio and 6-keto-PGF1 alpha CS/AO ratio in ASA group were significantly lower than those in NASA group (P < 0.05), but not different from those in control group. Both ASA and NASA groups had lower serum TXB2 CS/AO ratios than control group (P < 0.05). The results suggest that low dose aspirin inhibits selectively TXA2 synthesis in systemic circulation and inhibits synthesis and/or release of TXA2 and PGI2 equally (no selectivity) in coronary circulation, but could not completely inhibit intracoronary platelet activation.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

[A primary observation on the effect of cell fusion on metastatic potential of tumor cells].

Mouse spleen cells transfected with pSV2 neo by CaPO4 precipitation were fused with highly metastatic cell clone (PLA801-D95) from human large cell lung cancer cell line. Hybrid cell clone PMS-2 was obtained after G418(400/ml)selection. After injection of 7 x 10(6) PMS-2 cells into nude mice, there was a tumor nodule developed, but the metastatic foci could not be found while 3 x 10(6) PLA801-D95 cells would metastasize to lung and lymph nodes after they were injected into nude mice. It might indicate that sometime mouse spleen cells could not suppress tumor formation but the metastatic potential could be suppressed by the fusion of mouse spleen cells with the lung cancer cells. The results of growth curve, serum independence and incorporation rates of H-thymidine all showed that the growth rates of parental cells were higher than those of PMS-2. Our data suggest that suppression of tumorigenicity and metastatic potential could be controlled by different kinds of genes, and the cloning of metastasis suppressor gene by subtractive hybridization is ongoing in our laboratory.

Animals↗
PubMed1995

[Preparation of 125I-F(ab')2-DNR-liposomes and radioimmunoassay of their specific conjugating ability].

The F(ab')2-DNR-liposomes were prepared using F(ab')2 obtained from digested monoclonal antibody against human white cells HI30 (CD45). Their affinity constant for peripheral blood mononuclear cells was determined by radioimmunoassay. Ka = 2.0 x 10(9). A good specific conjugation ability was demonstrated. In preparing the immunoliposomes, it was found that F(ab')2 coupled to the smaller liposomes with higher conjugation ratio.

Antibiotics, Antineoplastic↗
PubMed1995

[A clinical study on multidrug resistance gene (MDR1) expression in acute leukemia].

The authors established a highly sensitive, specific and quantitative method-RT-PCR for measuring the levels of MDR1 mRNA in 91 acute leukemic samples (including 30 untreated cases, 32 remission cases, 29 refractory and relapse cases). The results showed that MDR1 mRNA positive rate for refractory and relapse cases, untreated cases and remission cases were 82.8%, 40.0%, 28.1% respectively. In untreated patients, it was found that the first complete remission rate differed significantly between MDR1 positive (41.7%) and MDR1 negative groups (88.9%) (P < 0.05). In remission group, MDR1 positive cases had a higher relapse rate than MDR1 negative case (66.7%; 13.0% P < 0.01) and all these cases relapsed of MDR1 gene overexpression (6 cases) were resistant to further treatment. It is concluded that the expression of MDR1 mRNA might be an unfavorable prognostic factor for patients with acute leukaemia and could predict the efficacy of intensive chemotherapy and serve as a high risk factor for early and resistant relapse.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Rapid non-empirical approaches for estimating relative binding free energies.

Rapid non-empirical methods for estimating binding free energies are reviewed. A novel approach based on the application of the free energy perturbation formula to a biased ensemble is presented. Preliminary results demonstrating the applicability of this approach in protein systems are shown and the potential of this method in structure-based drug design is discussed.

Models, Theoretical↗
PubMed1995

[The study of the relationship between the granule size of immunoliposomes and the conjugate ratio of F(ab')2 of McAb HI30 (CD45)].

The immunoliposomes were prepared by conjugating the F(ab')2 of monoclonal antibodies HI30(CD45) labelled by 125I with the liposomes labelled by 131I, and then were separated by a sephacryl S-300 column. The chromatography showed that the liposomes prepared by ultrasonic method were not homogeneous, and the liposomes of smaller granule size had a higher conjugate ratio. It was also found that the fragment F(ab')2 of McAb conjugated to liposomes could enlarge their granule size.

Animals↗
PubMed1995

[A study on the viability of corneal endothelium in rabbit by dual staining with trypan blue and alizanin red S].

PURPOSE: We study the viability of preserved rabbit corneal endothelium by dual staining with trypan blue and alizanin red S. METHOD: We randomly divided New Zealand white rabbit eyes into four groups, each with 5 eyes. The eye balls were preserved in moist chambers with aqueous remorad and C3F8 temponade for 5, 7, 10 and 14 days. Then we got the corneal Bottons with sclera ring. Isolated corneas were placed with the endothelial side up in a corneal cup, and trypan blue (0.25%) was added drop-wise to cover the endothelium. After 1.5 minutes the stain was poured out. The endothelial layer was then covered with aliznin red S (0.2%) for 1.5 minutes and pouring away the staining reagent. After staining, the corneas were immensec in glutaraldehyde fixative solution for 10 minutes. Finally, the endothelium was examinated and taken photoes with light microscope. RESULTS: Changed cells that have become permeable to trypan blue show deep blue staining of their nuclei in contrast to the unstained condition of normal cells. All the intercellular borders of endothelial cells were purple. The survival rate of the endothelium preserved for 5 and 7 day is more than 95%, for 10 days is 75-80%, and for 14 days about 70%. CONCLUSION: This technique allows a proportion cout of damaged and undamaged cells in the endothelial monolayer, makes it possible to observe their structures clearly and gives advantage to take pathelage photos.

Animals↗
PubMed1995

[Observation of corneal endothelial cells in modified mid-term preservation by scanning electronic microscope].

PURPOSE: To observe the ultramicroscopic structure of corneal endothelium in modified mid-term preservation. METHODS: Eyes of 4 New Zealand rabbits were enucleated. The 4 right eyes and additional 6 human eyes (as experiment group) were treated as follows: Aqueous was drawn off and replaced with equal volume of C3F8 air, then the whole eye was preserved in wet chamber at 4 degrees C, with 2 rabbit eyes being preserved for 7 days. 1 for 10 days and 1 for 14 days, and 6 human eyes for 0, 3, 5, 7, 10 and 14 days respectively. Corneas with 1 mm scleral ring of the 4 rabbit eyes (control group) were derived and preserved in Optisol nutrients at 4 degrees C for the same period of time. Corneas of all eyes were examined by scanning electronic microscope. RESULTS: For rabbit eyes, slight edema was found in the cornea preserved for 7 days, and loss of surface microvilli and cell lysis were found in those preserved for 10 and 14 days. For human eyes, no significant change was found in cornea preserved for 7 days, and different changes were found in those preserved longer. CONCLUSION: No significant change was found in cornea endothelium preserved by this method for 7 days.

Animals↗
PubMed1994

Suppression of hyphal formation in Candida albicans by mutation of a STE12 homolog.

A Candida albicans gene (CPH1) was cloned that encodes a protein homologous to Saccharomyces cerevisiae Ste12p, a transcription factor that is the target of the pheromone response mitogen-activated protein kinase cascade. CPH1 complements both the mating defect of ste12 haploids and the filamentous growth defect of ste12/ste12 diploids. Candida albicans strains without a functional CPH1 gene (cph1/cph1) show suppressed hyphal formation on solid medium. However, cph1/cph1 strains can still form hyphae in liquid culture and in response to serum. Thus, filamentous growth may be activated in C. albicans by the same signaling kinase cascade that activates Ste12p in S. cerevisiae; however, alternative pathways may exist in C. albicans.

Amino Acid Sequence↗
PubMed1994

Indolo[3,2-b]carbazole: a dietary-derived factor that exhibits both antiestrogenic and estrogenic activity.

BACKGROUND: Indole-3-carbinol (I3C) and related compounds have been identified in vegetables of the Brassica genus. I3C and its acid-derived condensation product, indolo[3,2-b]carbazole (ICZ), bind to the aryl hydrocarbon (Ah) receptor and induce CYP1A1/1A2 gene expression in both in vivo and in vitro models. I3C also inhibits mammary tumor development in rodent models. PURPOSE: The major focus of this study was to investigate the induction of CYP1A1-dependent activity and antiestrogenic effects of ICZ in the MCF-7 human breast cancer cell line and determine if induction of CYP1A1 is required for observed antiestrogenic responses. METHODS: The induction of CYP1A1 in MCF-7 cells was determined by measuring time- and concentration-dependent changes in ethoxyresorufin O-deethylase (EROD) activity in response to ICZ treatment. The effects of ICZ on occupied nuclear estrogen receptor (ER) levels and inhibition of estrogen (17 beta-estradiol [E2])-induced cell proliferation, [3H]thymidine uptake, secretion of the 52-kd protein, and nuclear progesterone receptor (PR) levels were also measured. Chloramphenicol acetyl transferase (CAT) activity was assayed in MCF-7 cells transiently transfected with an estrogen-responsive vit-CAT plasmid. Competitive binding to rat cytosolic ER was also examined. RESULTS: ICZ (> or = 10 nM) induced CYP1A1 in MCF-7 human breast cancer cells. This compound also elicited a diverse spectrum of antiestrogenic responses, including inhibition of E2-induced cell proliferation, [3H]thymidine uptake, occupied nuclear PR binding, and CAT activity in cells transfected with the estrogen-responsive vit-CAT plasmid. In nuclear extracts from ICZ-treated cells, there was a decrease in ER levels and binding to an estrogen-responsive element in a gel shift assay. I3C also decreased nuclear ER binding in MCF-7 cells. ICZ bound with low affinity to the ER and exhibited weak estrogen-like activity. CONCLUSIONS: Like other Ah receptor agonists, ICZ is antiestrogenic in human breast cancer cells, and this activity is consistent with the inhibitory activity of I3C on mammary tumor formation in rodents. ICZ-induced antiestrogenic responses can be observed at times or concentrations in which EROD activity is unchanged, indicating an interaction between the Ah receptor and ER-mediated endocrine pathways that is independent of P450-induced hormone metabolism. ICZ also is a weak estrogen in MCF-7 cells and binds to the ER. IMPLICATIONS: The current focus on the role of dietary and environmental estrogens in human disease should take into account the possible contra-active effects of Ah receptor agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), ICZ, I3C, and related compounds that exhibit antiestrogenic activity.

Base Sequence↗
PubMed1994

Escherichia coli proline tRNA synthetase is sensitive to changes in the core region of tRNA(Pro).

To investigate the relationship between tRNA conformation and specific recognition by aminoacyl-tRNA synthetases, a full-length tRNA molecule was assembled by annealing together two oligonucleotides representing fragments of Escherichia coli tRNA(Pro). A shorter chemically synthesized 5'-fragment (7-18 nucleotides) was combined with an in vitro transcribed 3'-fragment (59 nucleotides). Despite a break in the phosphodiester backbone between nucleotides U17a and G18, this tRNA molecule was an efficient substrate for class II Escherichia coli proline tRNA synthetase. While the deletion of three D-loop nucleotides (U17a, U17, and C16) was tolerated, removal of G15 and A14 significantly reduced aminoacylation efficiency. Hybrid DNA-RNA "annealed" substrates were also prepared and assayed for aminoacylation. Native gel electrophoresis was used to compare the global folding of the various substrates tested. The results of these studies suggest that proline tRNA synthetase is sensitive to changes in the core region of tRNA(Pro) through which information required for efficient aminoacylation may be transmitted. In particular, nucleotides in the D-loop and backbone functional groups in the D-stem appear to be critical for maintaining a tRNA structure that is optimal for recognition by proline tRNA synthetase in vitro.

Amino Acyl-tRNA Synthetases↗