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Biomedical subjects

H Ren

Publications and source records attributed to H Ren.

At least 127 records · Page 7Linked to original sources
PubMed1996

Apoptosis in the corneal epithelium.

PURPOSE: To determine the viability of corneal surface cells and to determine whether apoptosis is present in the corneal epithelium of the rabbit. METHODS: The viability of epithelial surface cells was examined using a calcein-ethidium assay. In this two-color fluorescence assay, viable cells fluoresce green, and the nuclei of nonviable cells fluoresce red. The number of nonviable cells on the normal corneal epithelial surface was quantified. Surface and shed cells also were examined from shear-stressed corneas. The TUNEL technique (TdT-mediated dUTP nick-end labeling) was used to detect DNA fragmentation characteristic of apoptotic cells. RESULTS: The calcein-ethidium viability assay revealed that the normal epithelial surface is composed mainly of viable cells, with nonviable cells making up a small percentage of the whole. There was an increase in the density of nonviable cells from the periphery of the epithelial surface to the center, In flatmounts of the cornea, TUNEL labeling demonstrated that a small percentage of surface cells exhibited DNA fragmentation, whereas cross-sections revealed that DNA-fragmented cells were found exclusively on the epithelial surface. Epithelial cells from shear-stressed corneas showed an increased number of apoptotic cells. CONCLUSIONS: The normal epithelial surface consists mainly of viable cells, with only a small percentage of nonviable cells and apoptotic cells. The results suggest that nonviable epithelial cells are shed after terminal differentiation, whereas viable cells can be shed by classical apoptosis with the formation of blebs. Thus, there appears to be more than one mechanism for removal of cells from the corneal surface.

Animals↗
PubMed1996

[Prevention of endotoxic shock in rats with hepatic stimulating substance].

In order to understand the mechanism of prevention of endotoxic shock and evaluate the pathological changes taking place, an animal model of endotoxic shock was established by intravenous injection of endotoxin into rats, which were then treated with a hepatic stimulating substance, hepatopoietin (HPN). The results were as follows; (1) There was coincidence of low blood pressure and high serum level of tumor necrosis factor (TNF) in the experimental rats. (2) Simultaneous intravenous injection of endotoxin and introperitoneal injection of HPN showed that HPN can prevent the drop of blood pressure, lower the TNF level and ameliorate the tissure injury in lungs and kidneys induced by endotoxin. If HPN was given 15 minutes ofter injection of endotoxin, the drop of blood pressure could not be prevented and the TNF level remained high. It is suggested that TNF is an important mediator for endotoxic shock and treatment of endotoxic shock might be effective, if it is intituted early.

Animals↗
PubMed1996

Pulmonary leiomyosarcoma--report of three cases.

Three cases of pulmonary leiomyosarcoma were presented. The characteristic clinical features were described with review of literature. In comparison with bronchogenic carcinoma, the leiomyosarcoma has some characteristics: 1) On chest X-ray, it usually appears as a sharply demarcated, even density round mass, growing rapidly within the lung, it rarely accompanies with hilar or mediastinal lymph node metastasis. 2) The preoperative cytological or pathological diagnosis is difficult either by sputum smear or by bronchoscopic biopsy or by fine needle percutaneous aspiration biopsy. 3) Pathological differential diagnosis of leiomyosarcoma of lung from anaplastic lung cancer is difficult. In conclusion, the primary pulmonary leiomyosarcoma is a rare malignant tumor, detecting the present illness seriously, paying attention to the chest X-ray films characterize, early surgical resection is the only way to get diagnosis and effective treatment method.

Adult↗
PubMed1996

[Effect of leaf picking on the output of radix Astragali seu Hedysari].

Based on an orthogonal design, the experiments have shown that proportion and time of leaf picking are the major factors to influence the thickness and output of Radix Astragali seu Hedysari. If the proportion is extended and the time is delayed, both the thickness and output of the roots will be reduced accordingly. The output will not change much if the time is set on around June 15 each year and the proportion is taken 1 out of 3.

Fabaceae↗
PubMed1995

NMR identification of calcineurin B residues affected by binding of a calcineurin A peptide.

Triple resonance 3D NMR methods have been used to study the interaction between calcineurin B and a peptide fragment of calcineurin A for which it has high affinity (KD approximately 4 x 10(-7) M). Although calcineurin B aggregates at NMR concentrations of approximately 1 mM, in the presence of a target peptide fragment of calcineurin A it becomes monomeric and yields NMR spectra that are very similar to those reported previously for calcineurin B solubilized by the zwitterionic detergent CHAPS. Changes in chemical shifts between CHAPS- and peptide-solubilized calcineurin B are small which is indicative of no differences in secondary structure. Residues most affected by binding to target peptide are found primarily on the hydrophobic faces of the four helices, present in each of the two globular domains in calcineurin B, and in the loops connecting helices II and III, IV and V, and possibly in the C-terminal 12 residues, which also exhibit a change in mobility.

Amino Acid Sequence↗
PubMed1995

Human adenosine A1 receptor gene: systematic screening for DNA sequence variation and linkage mapping on chromosome 1q31-32.1 using a silent polymorphism in the coding region.

Adenosine is a major inhibitory neuromodulator in the central nervous system. One of the receptors mediating the central effects of adenosine is the adenosine A1 receptor. We performed a systematic mutation scan of the coding region of the adenosine A1 receptor gene to explore its variability in the general population. Investigating 40 unrelated healthy subjects by single-strand conformation analysis no sequence changes of likely functional relevance were observed. We detected, however, a frequent T to G substitution at nucleotide position 716 which constitutes the first variant described in an adenosine receptor gene. It was used for fine scale linkage mapping of the A1 gene. Employing a polymerase-chain-reaction-based restriction assay, we genotyped 7 CEPH families (Centre d'Etude du Polymorphisme Humaine) and mapped the receptor in a gene cluster around the renin gene on chromosome 1q31-32.1. In addition, we utilized the 716T/G polymorphism to demonstrate biallelic expression of the adenosine A1 receptor gene in adult human brain.

Adult↗
PubMed1995

Rotational dynamics of calcium-free calmodulin studied by 15N-NMR relaxation measurements.

The backbone motions of calcium-free Xenopus calmodulin have been characterized by measurements of the 15N longitudinal relaxation times (T1) at 51 and 61 MHz, and by conducting transverse relaxation (T2), spin-locked transverse relaxation (T1 rho), and 15N-[1H] heteronuclear NOE measurements at 61 MHz 15N frequency. Although backbone amide hydrogen exchange experiments indicate that the N-terminal domain is more stable than calmodulin's C-terminal half, slowly exchanging backbone amide protons are found in all eight alpha-helices and in three of the four short beta-strands. This confirms that the calcium-free form consists of stable secondary structure and does not adopt a 'molten globule' type of structure. However, the C-terminal domain of calmodulin is subject to conformational exchange on a time scale of about 350 microseconds, which affects many of the C-terminal domain residues. This results in significant shortening of the 15N T2 values relative to T1 rho, whereas the T1 rho and T2 values are of similar magnitude in the N-terminal half of the protein. A model in which the motion of the protein is assumed to be isotropic suggests a rotational correlation time for the protein of about 8 ns but quantitatively does not agree with the magnetic field dependence of the T1 values and does not explain the different T2 values found for different alpha-helices in the N-terminal domain. These latter parameters are compatible with a flexible dumb-bell model in which each of calmodulin's two domains freely diffuse in a cone with a semi-angle of about 30 degrees and a time constant of about 3 ns, whereas the overall rotation of the protein occurs on a much slower time scale of about 12 ns. The difference in the transverse relaxation rates observed between the amides in helices C and D suggests that the change in interhelical angle upon calcium binding is less than predicted by Herzberg et al. Strynadka and James [Strynadka, N. C. J. & James, M. N. G. (1988) Proteins Struct. Funct. Genet. 3, 1-17].

Animals↗
PubMed1995

Solution structure of calcium-free calmodulin.

The three-dimensional structure of calmodulin in the absence of Ca2+ has been determined by three- and four-dimensional heteronuclear NMR experiments, including ROE, isotope-filtering combined with reverse labelling, and measurement of more than 700 three-bond J-couplings. In analogy with the Ca(2+)-ligated state of this protein, it consists of two small globular domains separated by a flexible linker, with no stable, direct contacts between the two domains. In the absence of Ca2+, the four helices in each of the two globular domains form a highly twisted bundle, capped by a short anti-parallel beta-sheet. This arrangement is qualitatively similar to that observed in the crystal structure of the Ca(2+)-free N-terminal domain of troponin C.

Animals↗
PubMed1995

[Expression of 12 antibody escape mutants of hepatitis B virus surface antigen gene in mammalian cell by using an Epstein-Barr based vector].

A 900bp DNA fragment of hepatitis B virus surface antigen gene by digesting BamHI and HpaI sites on the open reading frame of HBV DNA on plasmid pEcob6 containing double copes of HBV DNA was cloned into SmaI site on the phagmide vector pBluescribt SK +. From this recombinant vector, 12 hepatitis B virus surface antigen gene mutants were obtained by oligonucleotide-mediated site directed mutagenesis. The expression vector-pMEP4HBS mutants are constructed by sub-cloning all of these mutant fragments of hepatitis B virus surface antigen gene on pBluescritSK+HBSM into BsmHI and KpnI sites on an Epstein-Barr virus based on eukaryotic expression vector-pMEp4. The vector pMEp4HBSMs were transfected to human hepatocellular carcinoma cell line-HepG2 by calcium phosphate mediated transfection, and resistant cell clones were obtained 3 weeks after selecting by hygromycine B. The results of detection of HBsAg excreted by resistant cell clones with monoclonal antibody to HBsAg showed that all antibody escape mutants of HBsAg except mutant 145R, a substitution of arginine for glycine at amino acid 145 position in HBsAg, were positive.

Carcinoma, Hepatocellular↗
PubMed1995

Corneal epithelial fluorescein staining.

BACKGROUND: There is some difference of opinion in the literature about the nature of fluorescein staining of the epithelial surface. Most authors support the view that fluorescein staining is due to drop out of cells and pooling of fluorescein in the footprint. Others believe that fluorescein fills intercellular spaces. Others suggest that cells themselves stain with fluorescein. METHODS: Rabbit corneas were stained with fluorescein and examined with the biomicroscope and later with a higher magnification epifluorescent microscope following excision. RESULTS: Fluorescein staining was shown to be due to staining of individual cells. No evidence was found to support the contention that fluorescein resides in areas of cell drop out, or that staining was due to filling of intercellular spaces. Micropunctate staining is shown to be due to staining of cells in an optimum manner, which is referred to as hyperfluorescence. CONCLUSIONS: The recognition that fluorescein stains cells, even in the case of epithelial abrasion, allows reinterpretation of many staining phenomena, including "salt and pepper" staining.

Animals↗
PubMed1995

Diagnosis and surgical treatment of bronchogenic cysts.

Between 1974 and 1993, 22 patients with bronchogenic cysts were operated on in our hospital; there were 14 men and 8 women, ranging in age from 11 to 62 years. The cyst locations were mediastinal in 13 (59.1%) and intrapulmonary in 9 (40.9%). There were symptoms (chest pain and recurrent bronchiolitis) in 20 patients (91%). The preoperative complications included infection in the lung and in the cyst and dysphagia due to esophageal compression. Chest pain was the main symptom in mediastinal cyst and recurrent infection of lung in intrapulmonary cyst. Plain chest radiograms showed that a round shadow, occasional air-fluid levels, and peripheral calcification may be found in cysts. An operation is the best treatment for cysts. All cysts were completely excised. No postoperative complications, late complications, or recurrence developed in our patients.

Adolescent↗
PubMed1995

A comparison of the effects of the propofol versus midazolam during total intravenous anesthesia for gynecological surgery procedures.

The effects of propofol and midazolam as an intravenous anesthetic were compared in 40 ASA I-II patients undergoing gynecological surgery during total intravenous anesthesia (TIVA). They were divided into propofol group (P n = 20) and midazolam group (M n = 20) randomly. The anesthesia was designed for each group respectively. Here, we discuss the experimental method and the results, which indicate that propofol is not only an effective anesthetic but also has more rapid and head-clear recovery properties than midazolam.

Adult↗
PubMed1995

Separate promoters in the human A1 adenosine receptor gene direct the synthesis of distinct messenger RNAs that regulate receptor abundance.

There are two types of transcripts for the human A1, adenosine receptor. They are expressed in a tissue-specific manner in human tissues and contain distinct exons. Previously, it had appeared that the two transcripts may have occurred through alternative splicing. The transcript beta has two upstream AUG codons, which in transiently transfected COS-7 cells leads to a reduced level of receptor expression. When genomic sequence including sequences 5' to transcriptional start site, exon 1A, intron 1A, exon 1B, intron 1B, exon 2, and coding sequence was inserted into an expression vector (pCMV5/huA1), the resulting transcripts had the same overall structure as the transcripts present in human tissues. Primer extension and 5' rapid amplification of cDNA ends of mRNA from transfected cells revealed the transcription start sites for these two transcripts occurred in what previously had been termed introns. These results were confirmed with similar analysis of mRNA derived from human tissues. Two nonconsensus putative TATA boxes (TTAAGA and TTTAAA) are located upstream of the transcription start sites for transcripts alpha and beta. When the TATA boxes and their flanking sequences were fused to a firefly luciferase gene containing promoterless vector, both demonstrated strong promoter activity in Chinese hamster ovary cells. Promoter A directs the synthesis of transcript alpha, and promoter B directs the synthesis of transcript beta. Promoter A contains a series of AGG elements between the putative TATA box and the transcription start, which accounts for a major portion of the promoter activity based on deletion and mutation analysis. In general, promoter A is more active than promoter B in transfected cells. The nonconsensus TATA box in promoter B plays a more important role in promoter activity than the TATA box in promoter A. The human A1 adenosine receptor gene appears to use two separate promoters to direct synthesis of distinct transcripts, which can then regulate the relative abundance of A1 adenosine receptor in tissues. We have redefined the human A1 adenosine receptor gene structure based on these new data.

Animals↗
PubMed1994

Characterization of the lanthanide ion-binding properties of calcineurin-B using laser-induced luminescence spectroscopy.

Calcineurin (CaN) is a Ca2+/calmodulin-dependent protein phosphatase found in brain and other tissues. It is a heterodimer consisting of a catalytic subunit (CaN-A) and a Ca(2+)-binding regulatory subunit (CaN-B). The primary structure of CaN-B indicates that it, like calmodulin, is an EF-hand protein and binds four Ca2+ ions. Eu3+, due to its favorable spectroscopic and chemical properties, has been substituted for Ca2+ in CaN-B to determine the metal ion-binding properties of this "calmodulin-like" protein. Excitation of the 7F0-->5D0 transition of Eu3+ results in a spectrum similar to that of calmodulin, consisting of three peaks. Analysis of the spectral titration curves reveals four Eu(3+)-binding sites in CaN-B. The affinities vary: sites I and II have dissociation constants of 1.0 +/- 0.2 and 1.6 +/- 0.4 microM, respectively; the values for sites III and IV are Kd = 140 +/- 20 and Kd = 20 +/- 10 nM, respectively. Binding of Tb3+ is slightly weaker. Tb3+ luminescence, sensitized by tyrosine, reveals that for lanthanides the highest affinity sites lie in the C-terminal domain. Energy transfer distance measurements between Eu3+ and Nd3+ in sites III and IV reveal a separation of 10.5 +/- 0.5 A, which suggests that these sites are arranged in a typical EF-hand pair. This information indicates that the overall structure of CaN-B is similar to the dumbbell-shaped proteins troponin-C and calmodulin, but is more like TnC in its metal-binding properties.

Amino Acid Sequence↗