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Biomedical subjects

R C Yang

Publications and source records attributed to R C Yang.

At least 55 records · Page 3Linked to original sources
PubMed1992

Effects of lithium and haloperidol on human sperm motility in-vitro.

Two psychotropic drugs, lithium and haloperidol, were evaluated for their in-vitro effects on sperm motility using a transmembrane migration method. Sperm motility was measured either immediately after semen had been mixed with the drug or after a 2 h incubation period at 37 degrees C. Lithium inhibited human sperm motility in a dose-dependent manner with an EC50 of 10 mM when the semen-lithium mixture had been incubated. Sperm motility was increased to 127% of control when semen had been incubated with 0.027 microM haloperidol; this concentration was within the therapeutic range.

Dose-Response Relationship, Drug↗
PubMed1992

A possible role of heat shock proteins in human sperm motility.

The testicular spermatogenic stem and seminiferous tubular cells selectively synthesize heat shock proteins (Hsps) during heat stress. Hsps, synthesized from testicular cells and leukocytes, are identical in molecular masses as well as chemical properties. In this study, we induced the Hsps from leukocytes and investigated their in vitro effects on human sperm motility. Semen samples were divided into two parts, washed and unwashed. The whole blood was heated in 43 degrees C for 15 minutes for induction of Hsps. A trans-membrane migration method was used to examine the effect of heated blood plasma on human sperm motility. The main heat-induced proteins of leukocytes were detected by 2-D electrophoresis and Coomassie blue stain. Leukocytes treated by heat produced a large amount of Hsp72 and Hsp80, while only a small amount was observed in that of non-heated leukocytes. The heated blood plasma inhibited motility of washed sperm in a manner that was dose-dependent. In the presence of seminal plasma fluid, however, the inhibitory effects of heated plasma on human sperm motility could not be observed. It was concluded that the heat-induced substance(s) from leukocytes, which being highly possible the Hsps, interfered the mobility of wash human sperm and the inhibition might be antagonized by seminal plasma.

Heat-Shock Proteins↗
PubMed1991

Pentoxifylline stimulates human sperm motility both in vitro and after oral therapy.

Pentoxifylline is a haemorrheologic agent often used in the treatment of peripheral vascular disorders. In this study, we measured sperm motility with a trans-membrane migration method and investigated the effect of this drug in the treatment of male infertility. We found that pentoxifylline increased motility of ejaculated spermatozoa in vitro from both normal and asthenozoospermic samples. After giving pentoxifylline to patients with asthenozoospermia for 3 months, sperm motility significantly increased, but sperm concentration did not increase. From the above results, it can be concluded that pentoxifylline is a useful drug in the treatment of normogonadotropic asthenozoospermia.

Administration, Oral↗
PubMed1991

[Clinical and cellular biologic diagnosis of Cockayne syndrome: a case report].

We report a case of Cockayne syndrome. A 6-year-old boy presented with a progeroid face, dwarfism, psychomotor retardation, skin photosensitivity and retinal pigmented degeneration. Neurological study disclosed slowed nerve conduction velocities and a brain CT showed calcification in the basal ganglia. Auditory brain stem evoked potential showed prolonged interpeak latency of wave I to wave V. Laboratory evaluation revealed mild liver dysfunction and peripheral eosinophilia. Fibroblast cultures from the patient and his family were exposed to ultraviolet (UV) light of 254 nm, ranging from 1 to 10 J/m2. Under 1 J/m2 irradiation, the surviving fraction of the fibroblasts from the patient, his mother, and a control subject were 40%, 50%, 90% respectively. If the fibroblasts of these subjects were exposed to 2 J/m2 and 3 J/m2 irradiation, the surviving fraction changed to 10%, 22%, 80% and 1.5%, 9%, 68%, respectively. However, fibroblasts from his sister and father showed the same surviving fraction as the control. The study showed that fibroblasts from the patient and his mother were extremely sensitive to UV light irradiation. We also study the concentration of the pyrimidine dimer of DNA in the patient and the control subject. Pyrimidine dimer showed no difference between the patient and the normal subject before and after 24-hour UV irradiation. These results suggest that the sensitivity to UV of Cockayne fibroblasts may be due to a ligase deficiency or to a replicon initiation disturbance in Cockayne cells.

Cell Survival↗
PubMed1989

Two-dimensional electrophoresis aided by personal computer analysis for screening of mutant proteins in inherited diseases.

A rapid and reproducible method of two-dimensional electrophoresis was developed for screening of abnormal proteins expressed in fibroblasts from patients with inherited diseases. After silver staining, the electrophoresis gel was subjected to semiautomatic digitizer-personal computer analysis: scanning with an image sensor video camera connected to a digitizer, followed by quantitative determination and statistical analysis with a personal computer. The protein spots analyzed by this method showed quantitative variations of various degrees, particularly in 2 of 247 spots examined. Seven spots were not always detected in control and pathological cells in this study. Slight variations in molecular weight were observed in 3 different spots.

Adolescent↗
PubMed1989

Identification of three distinct Clostridium thermocellum xylanase genes by molecular cloning.

Three genes coding for xylanase synthesis in Clostridium thermocellum were cloned and expressed in Escherichia coli. Genomic DNA from Clostridium thermocellum was digested to completion with HindIII, BamHI, and SalI. The fragments were ligated into the corresponding sites of pUC19 and transformed into Escherichia coli. Two of the genes encoded for xylanases which depolymerized xylans but were unable to extensively convert these substrates to reducing sugar. The third gene encoded for an enzyme that extensively hydrolyzed xylan. The insert containing the latter gene was subjected to extensive mapping and was found to encode for a xylanase with a molecular weight of approximately 25,000. The protein product of the cloned gene was obtained in a relatively pure form by heat treatment, ion exchange and gel permeation steps. The enzyme was quite stable to high temperatures with a half-life of 24 h at 70 degrees C.

Cloning, Molecular↗
PubMed1989

Identification of two distinct Bacillus circulans xylanases by molecular cloning of the genes and expression in Escherichia coli.

Two genes coding for xylanase synthesis in Bacillus circulans were cloned and expressed in Escherichia coli. After digestion of genomic DNA from Bacillus circulans with EcoRI and PstI, the fragments were ligated into the corresponding sites of pUC19 and transformed into Escherichia coli. Restriction enzyme mapping of the two inserts coding for xylanase activity indicated distinctly different nucleotide sequences. Cross-hybridization assays confirmed the absence of sequence homology between the two genes. In vitro transcription-translation assays indicated that the cloned genes encoded for proteins with molecular weights of 22,000 and 59,000. The gene products displayed different substrate specificities. The 22,000-dalton enzyme readily hybrolyzed aspeen, larchwood, and oat spelt xylans, whereas the second was unable to extensively depolymerize oat spelt xylan and resulted in very limited reducing sugar release from any of the xylan substrates tested. Both of the xylanases had isoelectric points of approximately 9.0.

Bacillus↗
PubMed1989

Hyperexpression of a Bacillus circulans xylanase gene in Escherichia coli and characterization of the gene product.

A 4.0-kilobase (kb) fragment of Bacillus circulans genomic DNA inserted into pUC19 and encoding endoxylanase activity was subjected to a series of subclonings. A 1.0-kb HindIII-HincII subfragment was found to code for xylanase activity. Maximum expression levels were observed with a subclone that contained an additional 0.3-kb sequence upstream from the coding region. Enhancer sequences in the upstream region are thought to be responsible for these high expression levels. Southern hybridization analyses revealed that the cloned gene hybridized with genomic DNA from Bacillus subtilis and Bacillus polymyxa. Xylanase activity expressed by Escherichia coli harboring the cloned gene was located primarily in the intracellular fraction. Levels of up to 7 U/ml or 35 mg/liter were obtained. The protein product was purified by ion exchange and gel permeation chromatography. The xylanase had a molecular weight of 20,500 and an isoelectric point of 9.0.

Bacillus↗
PubMed1988

Molecular Cloning and Expression of a Xylanase Gene from Bacillus polymyxa in Escherichia coli.

Genomic fragments of Bacillus polymyxa derived from separate and complete digestion by EcoRI, HindIII, and BamHI were ligated into the corresponding sites of pBR322, and the resulting chimeric plasmids were transformed into Escherichia coli. Of 6,000 transformants screened, 1 (pBPX-277) produced a clear halo on Remazol brilliant blue xylan plates. The insert in the pBPX-277 recombinant, identified as an 8.0-kilobase BamHI fragment of B. polymyxa, was subsequently subjected to extensive mapping and a series of subclonings into pUC19. A 2.9-kilobase BamHI-EcoRI subfragment was found to code for xylanase activity. Xylanase activity expressed by E. coli harboring the cloned gene was located primarily in the periplasm and corresponded to one of two distinct xylanases produced by B. polymyxa. Xylanase expression by the cloned gene occurred in the absence of xylan and was reduced by glucose and xylose. Southern blot hybridization with the cloned fragment as a probe against complete genomic digests of the bacilli B. polymyxa, B. circulans, and B. subtilis revealed that the cloned xylanase gene was unique to B. polymyxa. The xylanase expressed by the cloned gene had a molecular weight of approximately 48,000 and an isoelectric point of 4.9.

Journal Article↗
PubMed1987

A simple differential immunoprecipitation assay of urinary acid and neutral alpha-glucosidases for glycogenosis II.

A specific assay for acid alpha-glucosidase in urine was developed to facilitate the diagnosis of glycogenosis II. This enzyme activity was calculated as a difference between the alpha-glucosidase activities before and after immunoprecipitation with antiserum to acid alpha-glucosidase. Acid alpha-glucosidase accounted for 86% of the total activity in control urine. All the cases of various clinical types of glycogenosis II showed either a marked decrease or a complete deficiency of this enzyme activity. A marked decrease of acid alpha-glucosidase was demonstrated by immunoblotting of the urine from patients with late-onset forms of this disease. These results indicate that assays of urinary acid alpha-glucosidase by this immunological method are useful for detection of the various types of glycogenosis II.

Adult↗
PubMed1986

The cloning and characterization of a RAS gene from Schizosaccharomyces pombe.

We have cloned and determined the complete nucleotide sequence of a RAS gene from the yeast Schizosaccharomyces pombe (SP-RAS). The putative RAS protein of 214 amino acids is encoded by two noncontiguous reading frames separated by an intron of 86 bp. The SP-RAS gene product shares extensive homology with the proteins of the Saccharomyces cerevisiae (SC), Dictyostelium, Drosophila, and human RAS genes in its N-terminal region but not in its C-terminal region. The extended C-terminal regions found in the SC-RAS genes have no counterpart in the SP-RAS gene. Thus the RAS genes of these two yeasts are structurally quite distinct. The SP-RAS sequence was expressed in vivo.

Base Sequence↗
PubMed1986

Complete nucleotide sequence and mRNA-mapping of the large subunit gene of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from Chlamydomonas moewusii.

Nucleotide (nt) sequence of the large subunit (LS) gene of ribulose-1,5-bisphosphate carboxylase/oxygenase from the green alga, Chlamydomonas moewusii, and mapping of transcription ends was achieved by two new strategies. The deduced LS sequence of 475 amino acid residues was compared with similar genes from six other species; cyanobacteria, land plants and a related alga (C. reinhardtii). The most conserved regions are the three ribulose bisphosphate binding sites and the CO2 activator site. The nt sequence conservation outside the coding region is limited to only three segments within the 5'-flanking region: a region of tandem repeats, TATAA box and ribosome-binding site. Termination point of transcription is an 'A' residue 3' to the first of two 18-nt inverted repeats, which has the potential to form a stem-loop hairpin structure. The possible role of these potential regulatory features for transcription and translation, and similar structures in other LS genes is presented.

Amino Acid Sequence↗
PubMed1983

An improved strategy for rapid direct sequencing of both strands of long DNA molecules cloned in a plasmid.

A strategy for kilo-base sequencing of a target DNA cloned in plasmid pWR34 is described. A long target DNA is progressively shortened from one end, by digestion with BAL31 nuclease or exonuclease III and nuclease S1, followed by cleaving off the shortened vector DNA. The family of the shortened target DNA molecule is next cloned in between the StuI site on one end, and a cohesive-ended restriction site on the other end, within the polylinker region of pWR34. DNA fragments cloned into this plasmid are sequenced directly by using a synthetic oligonucleotide primer, which binds to one side of the polylinker region using the dideoxynucleotide chain-termination method. The plasmid DNA, easily obtained by adoption of a rapid mini-preparation, is usually pure enough for direct DNA sequencing. Thus, both strands of any DNA several thousand base pairs in length can be completely sequenced (using two different primers) with ease within a short time, without the need for constructing a physical map.

Base Sequence↗