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R L Zhao

Publications and source records attributed to R L Zhao.

12 recordsLinked to original sources
PubMed2001

Phenotypic recombination between bean common mosaic and bean common mosaic necrosis potyviruses in vivo.

The US-5 strain of bean common mosaic virus (BCMV) and the NL-8 strain of bean common mosaic necrosis virus (BCMNV) are both seedborne potyviruses in common bean (Phaseolus vulgaris L). They have contrasting and highly stable biological characteristics which are genetically controlled. BCMV strain US-5 belongs to pathogenicity group IV. BCMNV strain NL-8 belongs to pathogenicity group III. The two strains have contrasting serological characteristics: NL-8 is serotype A; US-5 is serotype B. When these two strains were maintained separately or as a mixture for more than three years (39 serial transfers) or in more than 100 plants of either of two susceptible hosts, we were unable to isolate a single virus strain that exhibited mutant-like or recombinant-like characteristics. However, within 28 days (during the 1st passage) after these 2 strains were inoculated to opposite primary leaves of bean plants that were susceptible to one virus and resistant to the other, we were able to recover 17 strains that clearly possessed recombinations of various phenotypic characteristics from each of the two "parental" viruses. Three types of phenotypic characteristics were recombined singly or in combination during a single passage in vivo: 1) Biological characteristics known to be controlled by genes for pathogenicity; 2) Serotype; and 3) Temperature-induced hypersensitive vascular necrosis. Each of the phenotypic recombinant strains contained only pathogenicity genes or serological characteristics found in one or both parents. In no case did we isolate a strain that could be described as a random mutation or one that contained pathogenicity or serological characteristics which were not found in at least one parent strain. This is the first known demonstration of phenotypic recombinations between distinct potyviruses in vivo. Implications for the evolution of new virus strains through the use of resistant cultivars and its impact on breeding programs and bean seed production are discussed.

Antigens, Viral↗
PubMed2001

[lambda N gene expression regulated by the leader sequence].

It was reported recently that changing the TIR (translational initiation region) of lambda N gene resulted in the increasing expression of lambda N gene and it was regulated at translational level. According to the alignment, the leader sequence of lambda N gene had three parts: a code region for ORF lambda N, the upstream sequence of ORF lambda N and 17 bp of spacer between ORF lambda N and downstream of lambda N gene. ORF lambda N is an open reading frame located at upstream of lambda N gene coding a peptide of 19 amino acids. To study the mechanism of regulation of lambda N gene expression, three serials of plasmids with mutant leader region of lambda N gene were constructed. (1) pMC1403-XT, in which the start codon or the partial code of ORF lambda N was connected with lacZ to obtain the ORF lambda N-lacZ fusion gene and in which the ORF lambda N-lacZ expression was under the control of a strong trp/lac promoter; (2) The ORF lambda N mutants in which the termination codon TAA was introduced into ORF lambda N at different positions by site-directed mutagenesis to preterminate the ORF lambda N on plasmid pMC1403N; (3) Mutants in which a deletion was located at upstream ORF lambda N in the ORF lambda N mutants above. The results obtained from determination of the beta-galactosidase activity in the transformants harboring the different plasmids showed that the ORF lambda N-lacZ expression was suppressed by the ORF lambda N code region and the lambda N expression was increased in both the second and third serials of mutants. At the same time the results from RNA-DNA dot hybridization showed that the lambda N gene expression was regulated at translational level. Therefore it was predicted that the reason of relatively low expression for lambda N gene in pMC1403N was due to the low efficiency of ORF lambda N translation. There are two ways to increase the expression of lambda N gene. One is to preterminate the translation of ORF lambda N at a suitable position to decrease the ORF lambda N effects on downstream lambda N gene translation; the other is to change the upstream sequence of ORF lambda N to improve its translation efficiency.

5' Untranslated Regions↗
PubMed2000

Determination of sperm acrosin activity for evaluation of male fertility.

AIM: To investigate a simple method for assaying acrosin activity for the evaluation of male fertility. METHODS: The acrosin activity of 7.5 x 10(6) sperm without seminal plasma and acrosin activity inhibitors was assayed using N-alpha-benzoyl-DL-arginine-p-nitroanilide (BAPNA) and detergent (Triton X-100) as substrate. RESULTS: The acrosin activity of 60 normal fertile men (35 +/- 10 microIU/10(6) sperm ) was higher than that of 168 infertile men (16 +/- 8 microIU/10(6) sperm) (P < 0. 01). It was indicated that there was a significant positive correlation between the acrosin activity and the sperm motility (r > or = 0.6534, P < 0.01) and a significant negative correlation between the sperm malformed rate and the WBC number (r < or = -0.5426, P < 0.01). The temperature and time of incubation and the sperm concentration could influence the assay results. CONCLUSION: Acrosin activity is an important index for the evaluation of male fertility. The approach developed by the authors is a simple method for the determination of acrosin activity.

Acrosin↗
PubMed1994

[Non-operative regions extradural hematoma: a review of 5 cases].

The authors report five patients who developed non-operative regions extradural hematoma following removal of intracranial tumors (3 cases) or cystiform diseases (2 cases). 3 cases developed on the left hemicerebrum. 2 cases formed on the bilateral. 4 cases were supratentorial operations, one inferior tentorial. The causative mechanisms of hematoma formation were attributed to a rapid fall in intracranial pressure, an increased blood velocity and the patient's position during the operation. Unexplained cerebral swelling during operation or delayed post-operative recovery should be intensely investigated by CT scanning. An emergency operation is indicated when the hematoma volume is more than 30ml.

Adult↗
PubMed1993

[Late radiation brain necrosis: a brain tumor like mass].

7 cases of late radiation brain necrosis, most of them were diagnosed as intracranial brain tumor at admission, were reported. Histological confirmation was obtained on 4 cases through craniotomy. Generally this disease is occurred 1 to 3 years after radiation therapy. CT and MR image show a low-density (Long T1) with variable mass effect. It is generally not possible to differentiate it from brain tumor on radiological and clinical grounds. Steroid therapy and drugs which promote brain cell metabolism and provide nourishment for nerve tissue have been effective in the treatment of this disease. 3 to 4 weeks after medication, symptoms recovered remarkably and long -term prognosis was good. In this article, we have a discussion about the treatment and diagnosis of this disease.

Adenoma↗
PubMed1992

[Blood and urine prostaglandin E2 and prostaglandin F2 alpha in patients with chronic gastritis and peptic ulcer].

The blood and urine prostaglandin E2 (PGE2), Prostaglandin F2 alpha (PGF2 alpha) in 106 cases of chronic gastritis and peptic ulcer were investigated by RIA. Meanwhile, the relationship among PGE2, PGF2 alpha and the Syndromes of TCM were approached. The result showed: In comparing with the normal control, the blood and urine PGE2 of 106 cases were obviously higher (P < 0.01), but PGF2 alpha was not (P > 0.05). The urine PGE2 and PGF2 alpha of moderate gastritis were markedly higher than those of mild gastritis (P < 0.05), but there were no significant difference between blood PGE2, PGF2 alpha of moderate gastritis and those of mild gastritis (P > 0.05). The blood PGE2, PGE2/PGF2 alpha ratio of Dampness-Heat in Spleen-Stomach Syndrome and the blood PGE2/PGF2 alpha ratio of incoordination between Liver and Stomach Syndrome were higher than those of Spleen Stomach Deficiency Syndrome in all the cases (P < 0.05). Compared with the normal control, both the decreased amplitude of blood PGE2/urine PGE2 and increased amplitude of blood PGF2 alpha/urine PGF2 alpha ratio showed as following: Spleen-Stomach Deficiency Syndrome > incoordination between Liver and stomach Syndrome > Dampness-Heat in Spleen-Stomach Syndrome. This study suggested: (1) There was a close relation between PGE2 and chronic gastritis and peptic ulcer; (2) There was no correlation between blood PGE2, PGF2 alpha and urine PGE2, PGF2 alpha; (3) PG was possibly a useful objective parameter to the Syndrome Differentiation in TCM.

Adult↗
PubMed1990

Neonatal and maternal outcome in low-pelvic and midpelvic operative deliveries.

A retrospective analysis of low-pelvic and midpelvic operative deliveries (according to the new definitions by the American College of Obstetricians and Gynecologists, 1989) matched with cesarean section deliveries of similar station was undertaken. In all vaginally delivered groups there was significantly decreased maternal morbidity, maternal hospital stay, and estimated blood loss. In the midpelvic deliveries, there was a significant increase in the frequency of neonatal resuscitation and an increase in base deficit for the umbilical artery. In both the midforceps and low-forceps groups, there was a significant increase of neonates with cord arterial pH less than 7.10, and an increase of base deficit, even when cases of fetal distress were eliminated. The midforceps group also had an increased rate of admission to the intensive care nursery and an increase in the risk of significant birth trauma. In considering a midforceps or midvacuum operative delivery, the potential associated risks to the neonate must be balanced against the benefits to the mother.

Birth Injuries↗
PubMed1986

Dot-immunobinding assay in the serodiagnosis of human hydatid disease.

A rapid and convenient procedure for the indirect serological detection of anti-Echinococcus antibodies in human hydatid disease is described. Sheep hydatid cyst fluid was spotted on nitrocellulose membranes. All remaining unbound sites on the membrane were blocked with polyxyethylene sorbitan monolaurate (Tween 20). The immobilized antigens were then reacted first with human serum to be diagnosed followed by reaction with horse anti-human IgG conjugated with peroxidase or protein A conjugated with peroxidase. The conjugated enzyme was then detected by the formation of the blue-brown precipitate which permanently stained the nitrocellulose membrane when the peroxidase reacted with benzidine-HCl and hydrogen peroxide. The results indicate that the dot-immunobinding assay is sensitive, specific, economical, fast and safe for serodiagnosis of hydatid disease. This is the first report of diagnosing human hydatid disease by the dot-immunobinding assay.

Antibodies↗