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Biomedical subjects

R Wu

Publications and source records attributed to R Wu.

At least 379 records · Page 21Linked to original sources
PubMed1988

Alpha-factor-directed synthesis and secretion of beta-subunit of human choriogonadotropin (beta-hCG) in yeast S. cerevisiae.

A couple of shuttle vectors (pYNA and pYNB), containing a sequence coding for the leader region of the alpha-factor precursor (alpha-factor leader sequence) and the origin of 2 micron circle, were constructed. The cDNA for the beta-hCG (145aa) was fused in phase to the 3'-end of the alpha-factor leader sequence and transformed into the yeast Saccharomyces cerevisiae. The yeast cells carrying this hybrid gene synthesized and secreted a protein with the immunoactivity of beta-hCG in an amount of 45 micrograms per liter of culture. The preliminary characterization of this protein is also reported in this paper.

Amino Acid Sequence↗
PubMed1987

A new rice repetitive DNA shows sequence homology to both 5S RNA and tRNA.

Moderately repetitive DNA sequences are found in the genomes of all eucaryotes that have been examined. We now report the discovery of a novel, transcribed, moderately repetitive DNA sequence in a higher plant which is different from any of the known repetitive DNA sequences from any organism. We isolated a rice cDNA clone which hybridizes to multiple bands on genomic blot analysis. The sequence of this 352 bp cDNA contains four regions of homology to the wheat phenylalanine tRNA, including the polymerase III-type promoter. Unexpectedly, two regions of the same 352 bp sequence also show homology to the wheat 5S RNA sequence. Using the cDNA as a probe, we have isolated six genomic clones which contain long tandem repeats of 355 bp sequence, and have sequenced nine repeat units. Our findings suggest that the rice repetitive sequence may be an amplified pseudogene with sequence homology to both 5S RNA and tRNA, but organized as long tandem repeats resembling 5S RNA genes. This is the first example showing homology between the sequences of a moderately repetitive DNA with unknown function and 5S RNA.

Base Sequence↗
PubMed1987

Rice chloroplast DNA molecules are heterogeneous as revealed by DNA sequences of a cluster of genes.

We describe the isolation of two rice chloroplast HindIII fragments (9.5 kb and 5.3 kb) each containing a gene cluster coding for the large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL), beta and epsilon subunits of ATPase (atpB and atpE), tRNAmet (trnM) and tRNAval (trnV). All five genes contained in the 9.5 kb fragment are potentially functional, whereas in the 5.3 kb fragment, rbcL is truncated and atpB is frame-shift mutated. The copy number of the 9.5 kb fragment is 10 times that of the 5.3 kb fragment, indicating that the two fragments are probably located on different chloroplast genomes and represent two different (major and minor) genomic populations. Thus, the rice chloroplast genome appears to be heterogeneous, contrary to general belief. We also describe the isolation of a rice mitochondrial HindIII fragment (6.9 kb) which contains an almost complete transferred copy of this chloroplast gene cluster. In this transferred copy, the coding sequences of rbcL, atpE and trnM contain perfectly normal reading frames, whereas atpB has become grossly defective and trnV is truncated.

Adenosine Triphosphatases↗
PubMed1987

Relationships between heart rate and PR interval during physiological and pharmacological interventions.

The relationships between heart rates (HR) and corresponding PR intervals (PR) were studied in 12 healthy young subjects during rest, standing and graduated treadmill exercise to heart rates of 160 to 170 beats min-1 and during the infusion of isoprenaline to heart rates of 100 to 110 beats min-1. During exercise, PR diminished with increasing HR. Over the range of HR from 60 to 160 beats min-1 all 12 individual subjects exhibited negative linear correlations between HR and PR described by the equation: PR (ms) = -0.351 HR (beats min-1) + 176.7 for composite data. During isoprenaline infusion the PR interval also diminished with increasing heart rate. Over the range of HR from 60 to 110 beats min-1, 11 of the 12 subjects exhibited negative linear correlations between HR and PR described by the equation: PR (ms) = -0.582 HR (beats min-1) + 186.5 for composite data. The exercise model was used to study the indirect (or rate-dependent) effects and the direct actions on atrioventricular conduction of beta-adrenoceptor blocking drugs and calcium channel antagonists, alone and in combination, in three groups of healthy subjects. Control and placebo observations on HR and PR at rest, standing and during exercise in these additional subjects also exhibited individual inverse linear relationships between HR and PR. Following the administration of beta-adrenoceptor blockers, PR were prolonged more than expected at the HR observed. Rate-adjusted PR prolongation during exercise exceeded standing which exceeded resting, indicating greater beta-adrenoceptor blockade in atrioventricular nodal tissue than in sinoatrial nodal tissue at each level of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1987

[Satellite vasculitis of B or non-A non-B hepatitis. Diagnostic value of a provocation test by intradermal injection of histamine].

The histo-pathological lesions of hypersensitivity vasculitis (HV) consist in an inflammatory reaction to circulating immune complexes deposited on the vascular endothelium. A provocation test by intradermal injection of histamine was used to demonstrate HV in patients with chronic hepatitis. Three groups of patients were studied: 16 with chronic hepatitis and HV, 22 with chronic hepatitis without HV, 4 control subjects. Skin biopsy was performed before and 3 hours after intradermal histamine. The following markers were looked for in the serum, skin and liver of all patients with chronic hepatitis: HBV (HBs Ag and HBe Ag, anti-HBs, anti-HBe and anti-HBc in the serum, HBs and HBc Ag in the liver); non-A non-B (non-A, non-B Ag and antibody, anti non-A non-Bc in the serum, non-A, non-Bc Ag in the liver). Viral antigens were found in healthy skin in 2 cases (1 chronic A hepatitis, 1 vasculitis), and after injection of histamine in 9 cases (4 chronic A hepatitis, 5 vasculitis). Viral antigens were found on skin biopsy in 2 patients with negative sera. Significant skin changes after histamine were detected only in HV (75 p. 100) even in the absence of cutaneous vasculitis (6/12 positive cases). An intradermal histamine provocation test is a simple, non-invasive method for diagnosing HV.

Hepatitis, Chronic↗
PubMed1986

Simultaneous synthesis of human-, mouse- and chimeric epidermal growth factor genes via 'hybrid gene synthesis' approach.

Simultaneous synthesis of two DNA duplexes encoding human and mouse epidermal growth factors (EGF) was accomplished in a single step. A 174 b.p. DNA heteroduplex, with 16 single and double base pair mismatches, was designed. One strand encoded the human EGF, and the opposite strand indirectly encoded the mouse EGF. The heteroduplex DNA was synthesized by ligation of seven overlapping oligodeoxyribonucleotides with a linearized plasmid. After transformation in E. coli HB101 (recA 13), the resulting heteroduplex plasmid served as the template in plasmid replication. Two different plasmid progenies bearing either the human or mouse EGF-coding sequence were identified by colony hybridization using the appropriate probes. However, in E. coli JM103, the same process yielded plasmid progenies encoding different chimeric EGF molecules, presumably due to crossover of human and mouse EGF gene sequences.

Animals↗
PubMed1986

Effects of retinoids on human bronchial epithelial cells: differential regulation of hyaluronate synthesis and keratin protein synthesis.

Respiratory tract epithelia are one type of tissue targeted by vitamin A. In this study the effects of vitamin A and its analogs (retinoids) on human bronchial epithelial (HBE) cells have been investigated in a serum-free hormone-supplemented medium. This serum-free medium, which was developed for the long-term cultivation of protease-dissociated HBE cells, consists of Ham's F12 nutrient medium supplemented with insulin, transferrin, epidermal growth factor, hydrocortisone, cholera toxin, and bovine hypothalamus extract. Under these in vitro conditions, retinoids specifically stimulate the synthesis and secretion of hyaluronate (HA) and alter the pattern of synthesis of keratin proteins. In regard to HA, the degree of stimulation ranges from two-fold to ten-fold and is concentration dependent. In regard to keratin proteins, the most prominent effects of retinoids are inhibition of synthesis of the 48 kd and 50 kd keratin proteins (corresponding to cytokeratins 16 and 14, respectively, in the catalog of human cytokeratins; Moll et al., 1982) and stimulation of synthesis of the 40 kd and 52-54 kd proteins. The data indicate that retinoid effects on HA and keratin protein synthesis occur at different levels. The stimulation of HA synthesis occurs immediately after the addition of retinoid and cannot be prevented by pretreatment with actinomycin D, whereas the alterations in the pattern of keratin protein synthesis appear later and are inhibited by treatment with actinomycin D at or before the administration of retinoid. This study demonstrates that HBE cultures maintained in the serum-free condition can serve as an in vitro model to elucidate the mechanisms of retinoid actions.

Bronchi↗
PubMed1986

Evaluation of once daily endralazine in hypertension.

Endralazine, a novel vasodilator related to hydralazine, exhibits a longer half-life and is only minimally influenced by acetylator status. The antihypertensive action of once daily endralazine has been studied in 17 patients previously controlled with an antihypertensive regimen which included hydralazine and a beta-blocker. Hydralazine was discontinued but other medications were unchanged. Pre-study dosage of hydralazine ranged from 25 mg b.i.d. to 50 mg g.i.d., mean daily dose 126.5 mg. Endralazine was started at a dose of 10 mg o.d. and increased by 10 mg to a maximum of 40 mg o.d. until seated DBP was controlled below 95 mmHg. All 17 patients completed the study. Seated BP significantly decreased from 147.5/99.7 to 133.8/83.9 and standing BP from 145.8/99.2 to 133.6/87.3 mmHg. Ten patients (59%) were successfully controlled with endralazine once daily but 7 patients required twice daily dosage schedules because of lack of BP control at 24 h after dosing or excessive hypotension shortly after dosing. Other adverse effects were headache, palpitations and fatigue. There was a statistically insignificant average weight gain of 1 kg but pedal edema was not observed. Endralazine is an effective antihypertensive agent with adverse symptoms similar to those experienced with hydralazine.

Acetylation↗
PubMed1986

Evolution of cytochrome c genes and pseudogenes.

A statistical analysis of the nucleotide sequences of cytochrome c genes from four species of animals and two of yeast and of cytochrome c pseudogenes from rat, mouse, and human was conducted. It was estimated that animals and yeast diverged 1.2 billion years ago, that the two duplicated genes DC3 and DC4 in Drosophila diverged 520 million years ago, and that the two duplicated genes Iso-1 and Iso-2 in the yeast Saccharomyces cerevisiae diverged 200 million years ago. DC3 is expressed at a low level and has evolved 3 times faster than DC4. This observation supports the neutralist view that relaxation of functional constraints is a more likely cause of accelerated evolution following gene duplication than is advantageous mutation. All the rodent pseudogenes examined appear to be processed pseudogenes derived directly from the functional genes, and most of them apparently arose after the mouse-rat split. No event of gene conversion could be detected between any pair of the rodent pseudogenes. Our analysis suggests that the human cytochrome c gene has evolved at a rate comparable to the average rate for pseudogenes, whereas some human cytochrome c pseudogenes have evolved at an exceptionally low rate.

Animals↗
PubMed1986

Developing differentiated epithelial cell cultures: airway epithelial cells.

Recent progress in cell culture enables us to grow and to maintain differentiated epithelial cells in a serum-free defined culture environment. Such an epithelial cell culture system free from interference by other nonepithelial cell types should be used widely in studies related to toxicology, carcinogenesis, and disease-related problems. This approach will lead to a better understanding of pathological changes indicated in the injured epithelial layer. The gap of information existing between in vivo and in vitro can be bridged together by this simple epithelial cell culture system by carefully analyzing changes of cell properties from in vivo to in vitro and by the cell separation to enrich specific cell types in preparation. Furthermore, evidence has been accumulated suggesting that the properties of epithelial cells in culture are part of the integral cellular physiologies of epithelial cells in vivo. These properties are, in most cases, related to cell injury which is reparable even in vitro if the appropriate condition is provided. Using the airway epithelial cell culture system developed in our laboratory as an example, the above points are discussed. Finally, we have shown that a differentiated tracheal epithelium with a similar polarity as in vivo was established in the described serum-free culture condition.

Animals↗
PubMed1986

A simple and rapid nucleotide sequencing strategy and its application in analyzing a rice histone 3 gene.

An improved rapid method for sequencing a target DNA is described. A new plasmid, pAA-PZ1, which contains the origin of replication from phage M13 and a portion of the Tn9 transposon was constructed. A long fragment of target DNA cloned into this vector is progressively shortened in vivo from one end by transposon-mediated deletions. The plasmids carrying different lengths of target DNA are then made into single-stranded DNA in the same host upon infection with an M13 phage and their sequence is determined using the dideoxynucleotide chain-termination method. This method bypasses the in vitro enzymatic manipulations for progressive deletions and requires no subcloning. Using this strategy, we sequenced 1.3 kb of rice DNA containing a histone 3 gene within three weeks.

Amino Acid Sequence↗
PubMed1986

Nucleotide sequence of the rice cytochrome f gene and the presence of sequence variation near this gene.

The rice (Oryza sativa L. var. Labelle) chloroplast (cp) gene encoding cytochrome f has been isolated and sequenced. The coding region of this rice gene displays 95.1%, 85.3% and 85.2% nucleotide sequence homology with that of wheat, pea and spinach, respectively. To examine the cpDNA sequence variation in rice, cpDNA from Labelle and its parents, Belle Patna and Dawn was compared. Using the cytochrome f gene as the probe for hybridization, we found several differences in the size and number of restriction fragments in the cp genome of three rice varieties. An additional restriction fragment found in the Belle Patna cp suggests that this cp genome is either heterogeneous or contains two copies of cytochrome f gene per cpDNA.

Amino Acid Sequence↗