Biomedical subjects

H Zhu

Publications and source records attributed to H Zhu.

At least 541 records · Page 30Linked to original sources

PubMed1990

Detection of beta-thalassemia mutations in the Chinese using amplified DNA from dried blood specimens.

This paper describes DNA polymerase chain reaction (PCR) amplification directly from dried blood specimens for the detection of the beta-thalassemia mutation in China. Target DNA was amplified to span the beta-globin gene regions, which included ten types of mutation sites specific for Chinese beta-thalassemias. Ten kinds of oligonucleotide probes were constructed and used to hybridize with the amplified DNA. A total of 170 beta-thalassemia alleles originating from eastern, southwestern and southern China were analyzed. The results revealed that the distributions of different types of mutations were different in the three regions. The most common types in southern China were a frameshift at codons 41/42 and a C----T substitution at IVS II n.654, the most frequent types in southwestern China were codon 17 and IVS II n.654 mutations, and the predominant mutations in eastern China were frameshifts at codons 41/42 and 71/72.

Base Sequence↗

PubMed1990

Yeast K1 killer toxin forms ion channels in sensitive yeast spheroplasts and in artificial liposomes.

The patch-clamp technique was used to examine the plasma membranes of sensitive yeast spheroplasts exposed to partially purified killer toxin preparations. Asolectin liposomes in which the toxin was incorporated were also examined. Excised inside-out patches from these preparations often revealed at 118 pS conductance appearing in pairs. The current through this conductance flickered rapidly among three states: dwelling mostly at the unit-open state, less frequently at the two-unit-open state, and more rarely at the closed state. Membrane voltages from -80 to 80 mV had little influence on the opening probability. The current reversed near the equilibrium potential of K+ in asymmetric KCl solutions and also reversed near O mV at symmetric NaCl vs. KCl solutions. The two levels of the conductance were likely due to the toxin protein, as treatment of spheroplasts or liposomes with extracellular protein preparations from isogenic yeasts deleted for the toxin gene gave no such conductance levels. These results show that in vivo the killer-toxin fraction can form a cation channel that seldom closes regardless of membrane voltage. We suggest that this channel causes the death of sensitive yeast cells.

Cell Membrane↗

PubMed1990

Purification and Characterization of an Extracellular Acid Proteinase from the Ectomycorrhizal Fungus Hebeloma crustuliniforme.

Hebeloma crustuliniforme produced an extracellular acid proteinase in a liquid medium containing bovine serum albumin as the sole nitrogen source. The proteinase was purified 26-fold with 20% activity recovery and was shown to have a molecular weight of 37,800 (as indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) and an isoelectric point of 4.8 +/- 0.2. The enzyme was most active at 50 degrees C and pH 2.5 against bovine serum albumin and was stable in the absence of substrates at temperatures up to 45 degrees C and pHs between 2.0 and 5.0. Pepstatin A, diazoacetyl-dl-norleucine methylester, metallic ions Fe and Fe, and phenolic acids severely inhibited the enzyme activity, while antipain, leupeptin, N-alpha-p-tosyl-l-lysine chloromethyl ketone, and trypsin inhibitor inhibited the activity moderately. The proteinase hydrolyzed bovine serum albumin and cytochrome c rapidly compared with casein and azocasein but failed to hydrolyze any of the low-molecular-weight peptide derivatives tested.

Journal Article↗

PubMed1990

[Morphology and development of dopaminergic neurons in the cat retina].

Morphology and development of dopaminergic neurons has been studied in the kitten retina, using tyrosine hydroxylase (TH) immunocytochemistry. TH immunoreactive (TH+) cells are already presented in whole amount and sectioned retina at first postnatal day (P1). According to soma size, shape, dendritic process pattern and immunoreactivity, two classes, type I or large dark staining TH+ cells and type II or small light staining TH+ cells are recognized. The TH I cells which consisting of normal placed DA amacrine cells, displaced DA amacrine cells and DA interplex-form-like cells, gradually mature during postnatal development, while TH II cells decrease quickly and through disappear at P30. After eye opening TH I amacrine cells, especially their dendrites develop quickly. The soma diameters increase from 11.8 microns (P1) to 14.2 microns (P30). The dendritic fields increase in size and complexity. At P1 the thick radiating dendrites emerge from the cell body with small or large "spines" and many growth cones. At P13 the dendritic field is markedly enlarged and only a few growth cones can be seen on some stained dendrites. In addition, the dendritic spines are no longer apparent and they are a part of rudimentary rings. By P30 the dendritic plexus of TH+ dendrites and rings in the out most part of IPL, typical of the adult cells, are complete. The influence of light on the development of DA cells after eye opening and the possibility of neurotransmitter changing are discussed.

Animals↗

PubMed1990

[Successful axenic cultivation of a local human strain of Giardia lamblia in suckling gerbil].

G. lamblia cysts isolated from the fresh feces of a Giardia-infected boy in Beijing rural area were inoculated into suckling gerbils (Meriones unguiculatus). Trophozoites of G. lamblia obtained from the intestines of infected gerbils were cultivated in modified TYI-S-33 medium enriched with dehydrated bovine bile. The parasites grew luxuriantly and formed an intensive monolayer on the surface of the culture tube on day 14 after initial cultivation. The culture has been maintained for more than 12 months and more than 120 subcultures have been made. The growth curve of the organism showed that the peak growth of the trophozoites was attained at the 120th hour after seeding. The generation time was 15 +/- 2.0 hours. Periodic examinations of Giardia cultures for bacteria contamination, with Petri dishes of blood agar and beef broth, proved negative. After being cryopreserved in liquid nitrogen for 1 week or longer, the average viable rate of the organism was 65.7% and the resuscitated parasites grew luxuriantly in subcultures.

Animals↗

PubMed1990

[Study on the discrimination of bacteria by gas chromatographic profiles of cellular monosaccharides].

A procedure for obtaining gas chromatographic (GC) profiles of bacterial cellular monosaccharides was described. Some of the unknown component peaks in these profiles were identified. And, based on the complete linkage cluster analysis with the Euclidean distance coefficient, the interpretation of the resulting cellular monosaccharides of bacteria were performed by mini-computer. By means of this method, the discrimination of 5 species (24 strains) of aerobic endospore-forming bacteria. The results showed that there were defined differences between the profiles of cellular monosaccharides of B. anthracis and B. cereus. This procedure has provided a useful method for the classification and identification of microorganisms, for their physiological and biochemical studies, and for studies on their subcellular components.

Bacillus↗

PubMed1990

Establishment of an axenic culture of Giardia lamblia through preliminary passage in suckling gerbil.

Cysts of Giardia lamblia from fresh stool specimens of a 13-year-old boy, who lived in suburban Beijing and had suffered from recurrent diarrheas for years, were concentrated, purified and suspended in physiological saline. Six suckling gerbils (Meriones unguiculatus) were each inoculated with 0.2 ml of this suspension which contained 20,000 cysts/ml. On day 8 after inoculation, the infected animals were sacrificed and trophozoites of G. lamblia which appeared numerous in the upper small intestines were isolated aseptically. The trophozoites were inoculated into modified TYI-S-33 medium and cultivated at 37 C. On day 14 of cultivation, the organism grew luxuriantly and formed a cellular monolayer on the inner wall of the culture tube. The organism replicated every 15 +/- 2 hours and the peak growth occurred 120 hours after seeding. No bacterial growth was detected by repeatedly transferring the culture onto blood agar plates and into beef broths. Several lots of the culture have been subjected to cryopreservation in liquid nitrogen and the viability of the thawed organism ranged from 50% to 80% 1-10 weeks after being cryopreserved. The thawed parasites grew well in subcultures. This axenic culture has been maintained for one year and 4 months, and more than 150 subcultures have been made.

Adolescent↗

PubMed1990

Cloning and identification of a rabbit sperm membrane protein gene.

Antibodies raised against rabbit sperm membrane protein (rSMP-B) interacted with a rat testis cytosolic protein with an estimated molecular weight of 70 kD. The clone expressing rSMP-B was isolated by epitope selection from a rat testis lambda gt11 vector cDNA library. An Eco R1-cut 2.0 kb cDNA fragment encoding rSMP-B was identified. The cDNA fragment (RSD-1) was isolated, subcloned and restriction mapped. Dot hybridization analysis of mRNA prepared from human, rabbit and rat testes showed that the gene encoding rSMP-B is expressed in the testes of all three mammals.

Animals↗

PubMed1990

[Survey and analysis of incidence and relevant factors of osteoporosis in the elderly (with a report of 2041 cases)].

This paper reports the results of roentgenography of calcaneum in 2,041 persons without any underlying disease causing osteoporosis. The trabecular patterns of calcaneum were divided into 5 grades according to Jhamaria method. The incidence of osteoporosis is 18.18%, 25.96%, 54.80%, 67.33%, 85.45% and 90% and the average grading of calcaneum were 2.98, 2.96, 2.53, 2.11 and 2.14 in male and 3.50, 2.89, 2.50, 2.06, 1.60 and 1.61 in female in these aged groups respectively Serum Ca, P, Mg and Vitamin D were determined in 1,798 persons over 60 years of age. There is no significant difference among them Bone density was determined in 381 cases, showing 0.507 +/- 0.003, 0.598 +/- 0.095, 0.673 +/- 0.052, and 0.0645 +/- 0.095 among Jhamaria grading index I, II, III, IV. There is significant difference between 1-2 and 3-4 grading index, suggesting Jhamaria method gives a reliable, simple and applicable criterion for diagnosis of osteoporosis. The relevant factors influencing osteoporosis are discussed.

Adult↗

PubMed1990

[Analysis of cellular fatty acids of Enterobacteria species by gas chromatography-mass spectrometry].

Cellular fatty acid compositions of 15 Enterobacteria were analyzed by gas chromatography-mass spectrometry(GC-MS). About 30 fatty acids were detected in chromatograms, and 13 of them were chemically identified, e.i. C11:0, C12:0, C13:0, C14:0, C15:0, 2OH-C14:0, 3OH-C14:0, C16:1, C16:0, aC17:0, delta C17:0, C18:1 and C18:0. The major cellular fatty acids in all fifteen species were C16:0, C18:1, C15:0, C14:0, C16:1, C13:0, 3OH-C14:0 and C18:0. The cellular fatty acids of Enterobacteria species were characterized by normal straight-chain saturated acids and monounsaturated acids, of which the most abundant fatty acid was C16:0. 3OH-C14:0 was found in all strains of Enterobacteria, whereas 2OH-C14:0 was only found in strains of Serratia species. Other unknown compositions also would have been certain characteristics for bacteria. The present paper would provide some of useful reference data for chemotaxonomy and molecular microbiology of Enterobacteria.

Enterobacteriaceae↗

PubMed1990

[Repair of cicatricial deformities in neck region with trapezius musculocutaneous flap].

Dr. Demergasso was the first one who applied the musculocutaneous flap of trapezius clinically in plastic surgery in 1975. Here the author had obtained satisfactory results in five cases by using the similar musculocutaneous flap to repair cicatricial deformity on the same side of the neck. The author held that this flap is easy to be dissected and moved forward to repair some areas on the neck, between mandible and thorax, and in front of larynx. There is no consequent deformation in the donor region which is hidden backward. The blood supply of trapezius is rich enough to keep from any local necrosis of the flap after transplantation. The color of the skin is usually like the origin one.

Adolescent↗

PubMed1990

Effect of radix Salviae miltiorrhizae extract injection on survival of allogeneic heart transplantation.

The effect of Radix Salviae Miltiorrhizae (RSM), a commonly used herbal blood circulation invigorator for the treatment of blood stasis in traditional Chinese medicine, on the duration of allograft survival following heterotopic heart transplantation in experimental animals was observed. The results in three heart transplantation models--auricular free graft in mice, abdominal graft in rats and cervical graft in rabbits--suggested that RSM injection in an appropriate dosage prolonged the survival time of cardiac allograft. The herb showed no significant toxicity. It was also found that RSM injection had a synergic effect with corticosteroids against graft rejection.

Animals↗

PubMed1989

Functional expression of a yeast mitochondrial intron-encoded protein requires RNA processing at a conserved dodecamer sequence at the 3' end of the gene.

All mRNAs of yeast mitochondria are processed at their 3' ends within a conserved dodecamer sequence, 5'-AAUAAUAUUCUU-3'. A dominant nuclear suppressor, SUV3-I, was previously isolated because it suppresses a dodecamer deletion at the 3' end of the var1 gene. We have tested the effects of SUV3-1 on a mutant containing two adjacent transversions within a dodecamer at the 3' end of fit1, a gene located within the 1,143-base-pair intron of the 21S rRNA gene, whose product is a site-specific endonuclease required in crosses for the quantitative transmission of that intron to 21S alleles that lack it. The fit1 dodecamer mutations blocked both intron transmission and dodecamer cleavage, neither of which was suppressed by SUV3-1 when present in heterozygous or homozygous configurations. Unexpectedly, we found that SUV3-1 completely blocked cleavage of the wild-type fit1 dodecamer and, in SUV3-1 homozygous crosses, intron conversion. In addition, SUV3-1 resulted in at least a 40-fold increase in the amount of excised intron accumulated. Genetic analysis showed that these phenotypes resulted from the same mutation. We conclude that cleavage of a wild-type dodecamer sequence at the 3' end of the fit1 gene is essential for fit1 expression.

Base Sequence↗

PubMed1989

The role of a conserved dodecamer sequence in yeast mitochondrial gene expression.

All mRNAs on the yeast mitochondrial genome terminate at a conserved dodecamer sequence 5'-AAUAAUAUUCUU-3'. We have characterized two mutants with altered dodecamers. One contains a deletion of the dodecamer at the end of the var1 gene, and the other contains two adjacent transversions in the dodecamer at the end of the reading frame of fit1, a gene within the omega+ allele of the 21S rRNA gene. In each mutant, expression of the respective gene is blocked completely. A dominant nuclear suppressor, SUV3-1, was isolated that suppresses the var1 deletion but is without effect on the fit1 dodecamer mutations. Unexpectedly, however, we found that SUV3-1 blocks expression of the wild-type fit1 allele by blocking processing at its dodecamer. SUV3-1 has pleiotropic effects on mitochondrial gene expression, affecting RNA processing, RNA stability, and translation. Our results suggest that RNA metabolism and translation may be part of a multicomponent complex within mitochondria.

Base Sequence↗

PubMed1989

[Streptococcus mutans glucosyltransferase: isolation and its ability to synthesize polysaccharides].

The extracellular glucosyltransferases (GTF, EC 2.4.1.5) were extracted from trypticase yeast L-cystine culture supernatant of streptococcus mutans strains SSMC 167(g), 6715(g), SSMC 100 (c) and Ingbritt (c) by 60% saturated ammonium sulphate precipitation. The yield was more than 50%. All the enzyme preparations could synthesize both water-soluble and insoluble glucans. The results of polyacrylamide gel electrophoresis of enzyme preparations illustrated the complexity and multicomponent nature of the GTF of S. mutans. The abilities of synthesizing polysaccharides were different between S. mutans serotype g and serotype c. The ability of synthesizing water-soluble glucan was almost the same as that of synthesizing water-insoluble glucan for GTFs from the two S. mutans strains of serotype g, but the ability of synthesizing water-soluble glucan was 10-fold to that of synthesizing water-insoluble glucan for GTFs from other two strains serotype c. No frucotosyltransferase activity was found.

Glucans↗

PubMed1987

Determination of the carboxyl termini of the alpha and beta subunits of yeast K1 killer toxin. Requirement of a carboxypeptidase B-like activity for maturation.

The carboxyl-terminal sequences of the two polypeptide chains of the Saccharomyces cerevisiae K1 killer toxin were determined by protein sequencing and amino acid analysis of peptide fragments generated from the mature, secreted toxin. The COOH-terminal amino acid of the beta chain is histidine 316, the final residue encoded by the precursor gene. The COOH terminus of the alpha chain is at alanine 147 of the preprotoxin. Amino acid composition data for the purified toxin are consistent with that predicted from the gene sequence of the preprotoxin where the alpha and beta subunits consist of amino acid residues 45-147 and 234-316, respectively. The molecular weight of the mature alpha beta dimer is about 20,658. The COOH-terminal sequence determination completes the location of the toxin subunits in the precursor, and its configuration may be represented as prepropeptide-Pro-Arg-alpha-Arg-Arg-gamma-Lys-Arg-beta, where gamma represents the interstitial glycosylated peptide. The COOH terminal side of the paired basic residues (Arg-148 Arg-149 and Lys-232 Arg-233 of preprotoxin) are endoproteolytic processing sites for the product of the KEX2 gene (Julius, D., Brake, A., Blair, L., Kunisawa, R., and Thorner, J. (1984) Cell 37, 1075-1089), and thus maturation of the alpha subunit of killer toxin apparently requires a carboxypeptidase B-like activity. A possible candidate for this activity is the product of the KEX1 gene (Dmochowska, A., Dignard, D., Henning, D., Thomas, D.Y., and Bussey, H. (1987) Cell, in press).

Amino Acid Sequence↗

PubMed1987

Dextrorphan: an antagonist for phencyclidine receptors.

Radio-binding assay, bioassay and HPLC detection were used to observe the antagonistic effects of dextrorphan on PCP's actions. Dextrorphan displayed high affinity to PCP receptor in the rabbit mesenteric blood vessels. It had weak PCP-like bioactivity, but could antagonize PCP's action dose-dependently in vitro study with the rabbit ear artery preparation and shifted the dose-response curve of PCP to the right. After PCP administration, the content of norepinephrine in the vascular bath medium was increased, which was reversed by dextrorphan. Thus suggests that dextrorphan is an antagonist with very mild agonistic action for PCP receptors.

Animals↗

PubMed1987

RNA processing and expression of an intron-encoded protein in yeast mitochondria: role of a conserved dodecamer sequence.

The 3' ends of most Saccharomyces cerevisiae mitochondrial mRNAs terminate at a conserved dodecamer sequence, 5'-AAUAAUAUUCUU-3', of unknown function. We have studied the consequences of mutations within a dodecamer found in an 1,143-base-pair optional intron of the mitochondrial large (21S) rRNA gene on RNA processing. The dodecamer is situated at the 3' end of an expressed open reading frame (ORF) within that intron, and the mutations are two adjacent transversions that extend the intron ORF by 51 nucleotides. The strain harboring these mutations, L5-10-1, is defective in biased intron transmission in crosses to strains that lack the intron, as are other mutants which contain nucleotide changes within the ORF (I. G. Macreadie, R. M. Scott, A. R. Zinn, and R. A. Butow, Cell 41:395-402, 1985). However, unlike these other mutants, wild-type strains, or petites which retain the intron allele, L5-10-1 is defective in processing at the intron dodecamer. In addition, L5-10-1 lacks a prominent 2.7-kilobase RNA containing both intron and exon sequences and at least two of four RNAs that correspond to various forms of the excised intron. We propose that these RNAs, missing in L5-10-1 but present in all other strains examined, arise in part by processing at the intron dodecamer. In addition, in all strains examined, we have detected a novel processing activity in which precursor 21S rRNA transcripts are cleaved in the upstream exon, about 1,500 nucleotides from the 5' end of the RNA. This activity, together with 3' intron dodecamer cleavage, probably accounts for the 2.7-kilobase RNA species, a candidate for the mRNA for the intron-encoded protein.

Base Sequence↗