Biomedical subjects

L He

Publications and source records attributed to L He.

At least 307 records · Page 17Linked to original sources

PubMed1997

Interactions of Na+, H2O2 and the Na+-Ca2+ exchanger stimulate Ca2+ release in CK1.4 cells.

1. The present study aimed to demonstrate that interaction of cations, hydrogen peroxide (H2O2) and the Na(+)-Ca2+ exchanger stimulate Ca2+ release and oscillations of cytosolic Ca2+[Ca2+]i in non-transfected Chinese Hamster Ovary (CHO) C1 cells and in transfected CHO (CK1.4) cells that contained an expression vector coding the Na(+)-Ca2+ exchanger sequence. 2. The [45Ca2+] uptake assay, fura-2 fluorescence imaging and 2(2) and 2(3) factorial orthogonal statistics provide comparative, direct, efficient, quantitative and transient methods to delineate the effects of such interactions on Ca2+ influx, Ca2+ release and [Ca2+]i in C1 and CK1.4 cells. 3. In contrast to the control of either Na(+)-, Ca2(+)- or H2O2-free or C1 cells, an elevated [45Ca2+] uptake was induced by Ca2+, Na+ and H2O2 individually and in combination, intra-cellular Ca2+ release was activated by H2O2, and by combinations of either H2O2 and Na+, H2O2 and the Na(+)-Ca2+ exchanger, Na+ and the Na(+)-Ca2+ exchanger or by H2O2, Na+ and the Na(+)-Ca2+ exchanger and a rise in [Ca2+]i was triggered by H2O2, Na+ and a combination of Na+ and the Na(+)-Ca2+ exchanger. 4. These results indicate that interactions between H2O2, Na+ and the Na(+)-Ca2+ exchanger stimulate intracellular Ca2+ mobilization via Ca2(+)-induced Ca2+ release mechanisms, ATP-activated G-protein coupled P2y-purinoceptor-sensitive pathways, Na(+)-Ca2+ exchanger-mediated Ca2+ influx and cation-pi interaction (a strong non-covalent force between the cation and the pi face of an aromatic structure in the transmembrane protein). 5. The present findings provide important clues for understanding Ca2+ signal transduction mechanisms from the plasma membrane to the endoplasmic reticulum.

Animals↗

PubMed1997

NtrC is required for control of Klebsiella pneumoniae NifL activity.

In response to molecular oxygen and/or fixed nitrogen, the product of the Klebsiella pneumoniae nitrogen fixation L (nifL) gene inhibits NifA-mediated transcriptional activation. Nitrogen regulation of NifL function occurs at two levels: transcription of the nifLA operon is regulated by the general Ntr system, and the activity of NifL is controlled by an unknown mechanism. We have studied the regulation of NifL activity in Escherichia coli and Salmonella typhimurium by monitoring its inhibition of NifA-mediated expression of a K. pneumoniae phi(nifH'-'lacZ) fusion. The activity of the NifL protein transcribed from the tac promoter is regulated well in response to changes of oxygen and/or nitrogen status, indicating that no nif- or K. pneumoniae-specific product is required. Unexpectedly, strains carrying ntrC (glnG) null alleles failed to release NifL inhibition, despite the fact that synthesis of NifL was no longer under Ntr control. Additional evidence indicated that it is indeed the transcriptional activation capacity of NtrC, rather than its repression capacity, that is needed, and hence it is a plausible hypothesis that NtrC activates transcription of a gene(s) whose product(s) in turn functions to relieve NifL inhibition under nitrogen-limiting conditions.

Bacterial Proteins↗

PubMed1997

Deletion of the mouse GH-binding protein (mGHBP) mRNA polyadenylation and splicing sites does not abolish production of mGHBP.

In murine species, the GH receptor (mGHR) gene encodes a full-length membrane-anchored mGHR and a truncated soluble receptor ectodomain (the GH-binding protein; mGHBP). The mGHR and mGHBP mRNAs are generated by alternative pre-mRNA splicing. Similar GHR/GHBP pairs are generated in other species by proteolysis of the GHR. The regulation of GHBP expression and the biological role of GHBP are not clear. In order to begin to dissect the factors responsible for regulating expression of mGHR and mGHBP, we have cloned a mouse GH receptor/binding protein (mGHR/BP) minigene consisting of two mGHR cDNA fragments and an mGHR/BP genomic sequence, such that the mGHR and mGHBP can be derived from the minigene by mimicking native alternative pre-mRNA splicing. To study the possible role of selection of polyadenylation relative to the expression of mGHR and mGHBP, we deleted the two tandem poly A addition signals and the flanking AT-rich region within the exon (exon 8A) that encodes the carboxy terminus of mGHBP. In addition, two other mutated forms of the minigene, one containing a mutated alternative splice acceptor site (SAS) near exon 8A and the other possessing a deletion of the intron between exons 7 and 8A (intron 7/8A), were generated. Expression of the mGHR/BP minigene and its mutated forms in transfected mouse L cells revealed that removal of the polyadenylation signals diminished but did not abolish either mGHR or mGHBP production. However, mutation of the SAS yielded normal mGHR and an mGHBP which may be a result of the translation of an mRNA possessing an open reading frame in intron 7/8A. Additionally, removal of intron 7/8A abolished mGHR expression but resulted in mGHBP production. The results suggest that selection of alternative polyadenylation sites of the mGHR/BP gene does not play a major role in the regulation of expression of mGHR and mGHBP in vitro. These results also suggest that mutation of the SAS near exon 8A does not abolish the ability of mGHR/BP gene to produce an mGHBP that retains the ability to bind GH, although the new mGHBP may be different from the natural mGHBP at its carboxy terminus.

Amino Acid Sequence↗

PubMed1997

Changes of mu opioid receptor binding sites in rat brain following electroacupuncture.

With [3H]-ohmefentanyl as a ligand, autoradiographic technique was used to observe the effect of electroacupuncture (EA) on mu opioid receptor binding sites in the brain areas related to pain modulation. The results were as follows: (1) The distribution of the mu receptor in the rat central nervous system was consistent in general with the results reported previously. (2) After EA of Tsu-San-Li, the mu receptor binding sites were increased significantly in the following examined structures: the caudate nucleus, septal nucleus, medial preoptic area, amygdalaoid nucleus, periaqueducal gray, interpeduncular nucleus, nucleus raphe magnus, and cervical and lumbar enlargements. The results indicate that EA is able to increase mu binding sites in the brain areas related to analgesia, suggesting the enhancement of mu receptor function by EA.

Animals↗

PubMed1997

[Regulation of cardiovascular myogenic tone via G-protein-sensitive transmembrane signal pathways].

Effects of cellular hypoxia on [Ca2+]i in CK1.4 cells expressed Na(+)-Ca2+ exchange protein were determined by fura-2 fluorescence imaging. In vitro perfused of canine cardiovascular samples (37 degrees C), changes of aortic, cervical, pulmonary arterial smooth myogenic tone and cardiac papillary myogenic tone were measured by mechanic-electrical transducers via a computer-aid autosampling system. In the whole dogs, pharmacolkinetic parameters of a VISA agent at three dosages were calculated by 125Isod-1 scintillation counting according to a 6 x 6 statistical model. The results indicated that 1. hypoxia inhibited the Na(+)-Ca2+ exchange protein induced by and elevated Ca(2+)-influx and [Ca2+]i in the CK1.4 cells; 2. hypoxic perfusions depressed the AlF4-(-)activated myogenic vasoconstriction in aortic, cervical and pulmonary arteries, but facilitated the cardiac papillary myogenic contraction Ca(2+)-influx-induced, the finding was consistent with the first result; and 3. the VISA agent distributed in the cell together with AlF4- simulated and activated G-protein-sensitive transmembrane sygnal, and signhificantly improved the oxidative injuries of the transmembrane macrowolecules and cardiovascular contraction proteins such as Na(+)-Ca2+ exchange protein induced by hypoxia.

Animals↗

PubMed1997

[The effect of exercise on the androgen receptor binding capacity and the level of testosterone in the skeletal muscle].

Androgen receptor (AR) binding and testosterone (T) level of skeletal muscle of rat at the different conditions were observed in this study. The exhausted exercise could up-regulate the AR binding of levator ani muscle, but decrease the T level in quadriceps. The long term exhausted exercise had no effect on the AR binding of quadriceps. The fitness exercise could up-regulate the AR binding of quadriceps but have no significant effect on the T level in quadriceps. There was no effect on the AR binding but T level was increased after injection of HCG for 4 days in quadriceps. The increase of T level in skeletal muscle after injection of HCG for 4 days was higher than that for 8 days. From these results it is suggested that the effect of exercise on the regulation of hormone on skeletal muscle may be in two directions. Both AR binding capacity and T level must be considered in skeletal muscle anabolism.

Animals↗

PubMed1997

[Clinical analysis of 7 cases of mesenteric venous thrombosis].

7 patients with mesenteric venous thrombosis (MVT) were treated in Anzhen Hospital from 1984 to 1996. The patients were all operated on and the diagnosis was confirmed pathologically. Fine patients were cured and 2 died. We discussed the pathophsiology, pathogeny, clinical manifestation, diagnosis and treatment of MVT. Most of the patients presented with a clinical picture of acute abdomen and the diagnosis was made only at laparotomy. Close observation and proper laparotomy should be given to the doubtful cases. To reduce the mortality rate of MVT, we resected the bowel which looks normal in appearance but comprises the mesentery of thrombosis. Adequate anticoagulant therapy should be given as early as possible.

Adult↗

PubMed1997

[Optimazation of conditions for stereoselective reaction by enzyme-catalyzed acetylation].

Optically active endo-tricyclo-[5,2,1, 0(2,6)]deca-8-en-3,5-diol-5-acetate is a very useful chiral synthon for the synthesis of optically active natural products. In this paper, the optimal conditions for the synthesis of this compound was established by orthogonality test. Under these conditions, the chemical percentage yield of acetylation of (+) endo-tricyclo-[5,2,1,0(2,6)] deca-8-en-3,5-diol-5-acetate and its % e.e. can reach up to 81% and 98.3% respectively. The optimazation of the conditions is efficient for the reaction of enzyme-catalyzed esterification.

Acetylation↗

PubMed1997

[Photodynamic effect of 49 single laser photosensitizers on two human tumor cell lines in vitro].

OBJECTIVE: For comparing the photodynamic effect of 49 single laser photosensitizers on two human cancer cell lines. METHODS: After irradiation with a pulsed copper vapour laser, the SW1116 cell line of human colorectal cancer and K562 cell line of erythroleukemia were measured with MTT assay. IC50 and the cell survival rate were observed to evaluate the photodynamic effect of various 49 single photosensitizers. RESULTS: In 49 photosentizers, the structure formula of the leading 9 single photosensitizers belonged to homatoporphyrin group, the average IC50 of which was < or = 1.0 microgram/ml on both cell lines of. The photosensitizers currently used in the clinic, hematoporphyrin-3 (PSD-007), ranked 17th, with IC50 on both cell lines of 1.25 micrograms/ml and 3.75 micrograms/ml, respecively. CONCLUSION: The leading 16 single photosensitizer in ths series studied are better purified and more effective in photodynamic killing of human cancer cell lines in vitro. They can be used in lieu of PSD-007 for cancer treatment.

Colorectal Neoplasms↗

PubMed1997

[The effect of estrogen receptor level on the prognosis of the elderly breast cancer patients].

OBJECTIVE: To evaluate the effect of estrogen receptor (ER) on the prognosis of the elderly female breast cancer patients and the guidance for their post-operation therapy. METHODS: 134 cases of the elderly female breast cancer patients (> or = 60 year-old) were divided into two groups depending on their ER level. Kaplan-Meier method was used to estimate disease-free servival (DFS) rate from the date of surgery. RESULTS: There were 88 patients in ER (+) group and 46 patients in ER (-) group. The medium follow-up of the ER (+) and the ER (-) group was 92.5 and 85.5 months, respectively. The incidence of recurrence and metastasis was 20.5% (18/88) in the ER (+) group and 41.3% (19/46) in the ER (-) group (P < 0.02). CONCLUSION: Estrogen receptor is a reference factor to predict prognosis of breast cancer in elderly patients.

Aged↗

PubMed1997

The correlations of clinicopathologic features, hormone receptor level with the prognosis of breast cancer: report of 308 cases in elderly women.

OBJECTIVE: This study analyses the clinicopathologic features and hormone receptor level of breast cancer in aged patients (> or = 60 years) and explores the related factors of the prognosis. METHODS: For all patients, the clinical data and pathologic data were reviewed retrospectively. Follow-up data were available. Of the 308 cases, tumor specimens in 130 patients were subjected to hormone receptor analysis by a dextran-coated charcoal technique. RESULTS: Of the 308 cases, 82 cases were in stage I, 147 cases in stage II, 66 cases in stage III, and 13 cases in stage IV. Metastatic rate (axillary lymph nodes) was 35.7%. The overall postoperative 5- and 10-year survival rates were 70.8% and 50.5%, respectively. Estrogen receptor and progesterone receptor positive rates were 66.9% and 40.0%, respectively. The survival rate was decreased with the increasing grade of TNM (P < 0.01). The mortality rate of the breast cancer was related to the clinical stage and the hormone receptor level (P < 0.05). CONCLUSIONS: There was a relatively good prognosis in this series. The size of tumor, number of metastatic nodes and hormone receptor level were related to the prognosis.

Adenocarcinoma↗

PubMed1997

[Experimental study on increasing arterial oxygen saturation by healthy exerciser under hypoxia].

The study was carried out among 41 healthy subjects born in Shanghai (Sea level). They were divided into two groups. Group one (10 subjects) was studied at sea level in a hypobaric chamber (3000m). Group two (31 subjects) was studied in high altitude plateau (Xigatse at 3836m). Arterial oxygen saturation (SaO2), Heart Rate (HR), blood pressure (BP) and myocardial oxygen uptake (MVO2) were measured noninvasively with Nelleor N-200 pulse Oxymeter and HEM-812F-Digital Automatic Blood Pressure Monitor. SaO2 increased significantly (from 87.7 +/- 1.7% to 95.3 +/- 1.0% P<0.01 and from 86.4 +/-1.0% to 91.8 +/- 0.6%, P < 0.05, respectively) by healthy exerciser through 15 min in both groups. After 3 min exercise SaO2 was still significantly higher than before exercise. Then HR, BP and MVO2 have not change significantly. The study results suggested that this kind of exerciser may help increasing the SaO2 and thus could be used to prevent and treat acute hypoxic response to some extent.

Altitude↗

PubMed1997

[Cloning and sequencing of cDNA of E2/NS1 gene of hepatitis C virus].

Hepatitis C virus (HCV) RNA extracted from serum of a patient infected with HCV in Beijing was converted to cDNA by reverse transcription. HCV E2/NS1 gene (approximately 930 bp) was amplified by nested polymerase chain reaction and was inserted into pGEM-T plasmid vector. The 431 bp nucleotide sequence at 5' terminus of this gene was determined by dideoxy-mediated chain termination method. The result of comparison of this sequence and sequences of another 9 HCV isolates suggested that the isolate we obtained was highly homologous to HCV genotype II. There are two hypervariable regions (HVR) at the N terminus of envelope protein encoded by HCV E2/NS1 gene. Several relatively conserved amino acid residues and areas located in and out of HVR were also observed. They are concerned in maintenance of spatial conformation of HCV envelope protein, but their immune function remains to be further studied.

Amino Acid Sequence↗

PubMed1997

DynorphinA-(2-17) restores spinal/supraspinal morphine synergy in morphine-tolerant mice.

Morphine administered simultaneously to intracerebroventricular (i.c.v.) and intrathecal (i.t.) sites exhibits synergism, with the antinociceptive potency much greater than would be predicted from a simple addition of the potencies of the same dose administered to either site alone. This synergism was quantified in mice using both a fixed dose method, in which the morphine dose at one site was fixed while the AD50 (antinociceptive dose at 50% effectiveness) of morphine at the other site was determined; and a variable dose method, in which different doses of morphine were administered simultaneously to both sites at a fixed ratio, and the AD50 determined and compared to the AD50 at a single site alone. When animals were made tolerant to morphine by implantation of a 75-mg morphine pellet for 3 days, this synergism was eliminated, so that morphine administered simultaneously to i.c.v. and i.t. sites had an additive effect. However, administration of the peptide DynorphinA-(2-17) i.v. simultaneously to the test doses of morphine in morphine-tolerant animals resulted in a partial restoration of synergism. These results suggest that morphine-induced antinociception is highly dependent on an intact integrated central nervous system system and that the initial tolerance development is the result of a disruption of synergism between the central nervous system sites. Morphine tolerance results not from a reduced sensitivity to morphine at discrete central nervous system sites, but rather from a reduced synergistic interaction of morphine at spinal and supraspinal sites. In support of this conclusion, there was no tolerance observed in morphine-pelleted animals to morphine administered to i.c.v. or i.t. sites alone. DynorphinA-(2-17), a nonopioid peptide has previously been shown to enhance the antinociceptive potency of morphine in morphine-tolerant animals, appears to act by restoring this synergism.

Animals↗

PubMed1997

[Expression of Cath-D, P-gp and Her-2 in carcinoma of the cardia].

OBJECTIVE: To investigate if Cath-D, P-gp and Her-2 are correlated with prognosis in patients with cardiac carcinoma. METHODS: Histological sections of 43 patients with cardiac cancer were tested by immunohistochemistry and analyzed for pathological type and lymphatic metastasis. RESULTS: The research show and that P-gp and Her-2 were not significant in predicting lymphatic metastasis (P > 0.05), but Cath-D positive was significant in lymphatic metastasis (P < 0.01). The P-gp and Cath-D were not significant in differential level of cardiac carcinoma and expression of Her-2 was significant (P < 0.05). CONCLUSION: The results suggest that positive Cath-D is correlated with metastases and positive Her-2 indicates poor survival. Special treatment plans for patients with carcinoma of the cardia should be designed depending on the above marker tests.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

[Diet and antioxidant--a nutritional intervention study].

It has been implicated that high vegetable intake is associated with a decreased risk for various forms of cancer in epidemiological studies. A major defense system against cancer has shown to be antioxidants. Glutathione S-transferases (GSTs), one of the major defense ststems against oxidative damage, can be induced by antioxidant and addition of vegetables to their normal diet. Serum retinol and a-tocopherol were determined by HPLC and the gene expression of GST pi in lymphocytes was measured by reverse transcription-polymerase chain reaction (RT-PCR) techniques. The results showed that there was on significant difference in the levels of serum retinol and a-tocopherol before and after the addition of vegetables. GST pi mRNA levels in lymphocytes were higher in four out of five subjects after addition of vegetables. The results suggested that it might be other antioxidants than vitamin A and E in the vegetables that induced the gene transcription of GST pi.

Adult↗

PubMed1996

Particle-mediated gene transfer with transforming growth factor-beta1 cDNAs enhances wound repair in rat skin.

Based on preliminary but variable results with direct DNA transfer into wounds, we evaluated in vivo gene transfer by particle-mediated DNA delivery to rat skin to determine whether overexpression of TGF-beta1 at the site of skin incisions would result in a significant improvement in repair. Optimization of the method with viral promoter-luciferase reporter constructs indicated that expression of luciferase activity persisted up to 5 d and was promoter, pressure, and site dependent (ventral > dorsal). Using cytomegalovirus (CMV)-driven human alpha1-antitrypsin, transgene expression was immunolocalized within keratinocytes of the stratum granulosum at 24 h. We measured tensile strength of skin incisions at 11-21 d in both normal and diabetic rats transfected with TGF-beta1 expression vectors at surgery. Native murine TGF-beta1 under an SV40 promoter produced positive effects, while wound strengthening was more pronounced in diabetic animals using a CMV-driven construct. Transfection of rat skin with constitutively active, mutant porcine TGF-beta1 under the control of the CMV and Moloney murine leukemia virus promoters significantly increased tensile strength up to 80% for 14-21 d after surgery. Transfection 24 h before surgery was more effective. Particle-mediated gene delivery can be used to deliver viral promoter-cytokine expression constructs into rat skin in a safe, efficient, and reproducible fashion. The extent of wound repair, as evidenced by enhanced tensile strength, can be markedly improved in tissues transfected with TGF-beta1 expression constructs.

Animals↗

PubMed1996

Comparison of flow cytometry and western blotting to measure Hsp70.

The levels of constitutive and inducible forms of heat shock protein 70 (hsp73 and hsp72, respectively) through the cell cycle were measured in CHO cells by flow cytometry and Western blotting at various times after heating. Cells were labeled with antibody C92 (hsp72) or N27 (hsp73) and propidium iodide prior to analysis by flow cytometry. Cells were heated for 15 min at 45 degrees C, then analyzed from 3 to 36 h later. There was about a tenfold increase in hsp72 in early S phase cells beginning within 6 h after heating and these cells gradually cycled though S phase so by 36 h most of them had divided. When CHO cells were exposed to 10 microM sodium vanadate, an inhibitor of tyrosine phosphatase, for 24 h prior to heating, the induction of hsp72 in early S phase cells was almost completely inhibited. Heated cells did not express hsp73 in a cell-cycle-dependent manner. Hsp73 increased uniformly in all cells by 10 h after heating and sodium vanadate did not affect the expression. Quantitative comparisons of the relative levels of hsp72 and hsp73 measured by flow cytometry and Western blotting were in excellent agreement. Control and heated cells were labeled with Hoechst 33342 and sorted from G1, S, and G2/M phases and processed by Western blotting to verify the cell cycle dependent increase in hsp72 as measured by flow cytometry. Again there was excellent agreement between the Western blotting and flow cytometry results.

Animals↗