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Biomedical subjects

R Zhou

Publications and source records attributed to R Zhou.

At least 163 records · Page 9Linked to original sources
PubMed1995

Immunogold labeling of oncogenic and tumor related proteins.

Immunogold labeling electron microscopy technique has been used to study the ultrastructural localization of oncogenic proteins: Mos, Met, Ski, and the tumor-associated protein, Muc1, as well as their relationship with other tumor-related proteins. By pre- and postembedding immunogold labeling electron microscopy techniques, we showed that the Mos protein pp39mos colocalized with microtubule bundles, suggesting that microtubulin or microtubule-associated protein(s) may be the substrate of Mos. Met protein was labeled at the microvilli of the lumen that are formed in cultured T47D cells, implying its potential involvement in lumen formation. Ski localization experiments revealed a unique globular structure "Ski body" that is present inside the nucleus of interphase chicken embryo fibroblast infected with Ski cDNA FB29 and FB2-29. Ski bodies were also found scattered in the cytoplasm of metaphase FB29 and FB2-29 Ski expressing chicken embryo fibroblasts. In T47D cells, tumor-associated protein Muc1 was associated with both the plasma membrane and the membranes of secretory vesicles in the cytoplasm. In MUC1 infected NIH3T3 cells, however, labeling showed that in addition to the plasma membrane and the membranes of secretory vesicles, some Muc1 gold spheres were seen inside the secretory vesicles, suggesting that the subcellular localization of the protein may vary in different cell types.

3T3 Cells↗
PubMed1995

Isolation and expression analysis of tyro3, a murine growth factor receptor tyrosine kinase preferentially expressed in adult brain.

Growth factors and their receptors function in the nervous system to induce proliferation and differentiation of neuronal precursor cells and to support survival of mature neurons. We have isolated a murine growth factor receptor tyrosine kinase using an anti-phosphotyrosine antibody screening procedure and studied the pattern of expression. The deduced amino acid sequence of the kinase has all the characteristics of a growth factor receptor and consists of a putative extracellular domain, a transmembrane domain, and a tyrosine kinase domain. Sequence comparison with known receptor tyrosine kinases indicated that the murine kinase is a mouse homolog of tyro3. tyro3 belongs to the Axl/Ufo growth factor receptor family. In the putative extracellular domain, there are two Ig-like domains and two fibronectin type III repeats which are conserved in other members of the Axl/Ufo family receptors. Northern blot hybridization analysis showed that tyro3 is expressed at high levels in the brain of adult mice, although considerable expression was also observed in the testis. In situ hybridization analysis revealed that high levels of tyro3 are expressed in the cerebral cortex, the lateral septum, the hippocampus, the olfactory bulb, and in the cerebellum. The highest levels of tyro3 expression in the brain are associated with neurons. The preferential expression of tyro3 in specific regions of the adult mouse brain suggests that tyro3 may function as a novel neurotrophic factor receptor.

Amino Acid Sequence↗
PubMed1995

Anatomical and physiological measures of auditory system in mice with peripheral myelin deficiency.

Animal models with genetic abnormalities have been increasingly used in auditory research. Both TrJ mice and Po-DT-A mice are animals with peripheral myelin deficiency. In TrJ mice, the defect is due to a mutated PMP-22 gene. In Po-DT-A mice, the defect is produced by a transgene using the rat Po promotor to direct the expression of gene encoding for the bacterial diphtherial toxin A chain (DT-A). This study evaluates the auditory system both physiologically and histologically in these two strains of mice. Histological examination revealed that there was myelin deficiency of the auditory nerve fibers, accompanied by a loss of dendrites and a loss of spiral ganglion cell bodies in both strains of mice. In general, histological deficits in TrJ mice were greater than those in Po-DT-A mice. There was a strong correlation between the degree of myelin deficiency and the survival of spiral ganglion neurons. ABR measurements exhibited differences in threshold, latency and slope of the ABR growth function between myelin-deficient mice and their respective controls. These results suggest that the integrity of the myelin in the auditory nerve is important both for neural survival and for normal electrophysiological function of spiral ganglion neurons.

Acoustic Stimulation↗
PubMed1995

Electrically evoked auditory brainstem response in peripherally myelin-deficient mice.

The integrity of the myelin sheath is important for normal electrophysiological function and survival of neurons that make up the auditory nerve. It is hypothesized that myelin deficiency of the auditory nerve may change the electrophysiologic characteristics of the auditory system, especially the temporal properties. In this study, the electrically evoked auditory brainstem response (EABR) was systematically evaluated in TrJ and Po-DT-A mice. Both of these mice have a deficit of their peripheral myelin. Correlation between the EABR and degree of myelin deficiency was also evaluated. The EABR in both strains of poorly myelinated mice exhibited prolonged latency, decreased amplitude, elevated threshold of wave I evoked by short-duration stimuli (20 microseconds/phase). A 2-pulse stimulation paradigm was used to evaluate refractory properties. Myelin-deficient mice exhibited slower recovery from the refractory state than controls. Long-duration stimuli (4 ms/phase) were used to assess integration properties. Myelin-deficient mice demonstrated prolonged wave I latency and more gradual latency changes with current level. Myelin thickness showed a strong correlation with EABR threshold for short-duration stimulation (r = -0.784), maximum wave I latency (r = -0.778) and the time constant of the wave I latency-current level function (r = -0.736) for long-duration stimulation and normalized wave I recovery functions (r = -0.718). These findings suggest that EABR measurement may be a promising tool to assess the electrically stimulated properties of auditory neurons, particularly related to the status of myelin sheath.

Animals↗
PubMed1995

Physical and transcriptional map of an aflatoxin gene cluster in Aspergillus parasiticus and functional disruption of a gene involved early in the aflatoxin pathway.

Two genes involved in aflatoxin B1 (AFB1) biosynthesis in Aspergillus parasiticus, nor-1 and ver-1, were localized to a 35-kb region on one A. parasiticus chromosome and to the genomic DNA fragment carried on a single cosmid, NorA. A physical and transcriptional map of the 35-kb genomic DNA insert in cosmid NorA was prepared to help determine whether other genes located in the nor-1-ver-1 region were involved in aflatoxin synthesis. Northern (RNA) analysis performed on RNA isolated from A. parasiticus SU1 grown in aflatoxin-inducing medium localized 14 RNA transcripts encoded by this region. Eight of these transcripts, previously unidentified, showed a pattern of accumulation similar to that of nor-1 and ver-1, suggesting possible involvement in AFB1 synthesis. To directly test this hypothesis, gene-1, encoding one of the eight transcripts, was disrupted in A. parasiticus CS10, which accumulates the aflatoxin precursor versicolorin A, by insertion of plasmid pAPNVES4. Thin-layer chromatography revealed that gene-1 disruptant clones no longer accumulated versicolorin A. Southern hybridization analysis of these clones indicated that gene-1 had been disrupted by insertion of the disruption vector. These data confirmed that gene-1 is directly involved in AFB1 synthesis. The predicted amino acid sequence of two regions of gene-1 showed a high degree of identity and similarity with the beta-ketoacyl-synthase and acyltransferase functional domains of polyketide synthases, consistent with a proposed role for gene-1 in polyketide backbone synthesis.

Aflatoxin B1↗
PubMed1995

Branchpoint and polypyrimidine tract mutations mediating the loss and partial recovery of the Moloney murine sarcoma virus MuSVts110 thermosensitive splicing phenotype.

Balanced splicing of retroviral RNAs is mediated by weak signals at the 3' splice site (ss) acting in concert with other cis elements. Moloney murine sarcoma virus MuSVts110 shows a similar balance between unspliced and spliced RNAs, differing only in that the splicing of its RNA is, in addition, growth temperature sensitive. We have generated N-nitroso-N-methylurea (NMU)-treated MuSVts110 revertants in which splicing was virtually complete at all temperatures and have investigated the molecular basis of this reversion on the assumption that the findings would reveal cis-acting elements controlling MuSVts110 splicing thermosensitivity. In a representative revertant (NMU-20), we found that complete splicing was conferred by a G-to-A substitution generating a consensus branchpoint (BP) signal (-CCCUGGC- to -CCCUGAC- [termed G(-25)A]) at -25 relative to the 3' ss. Weakening this BP to -CCCGAC- [G(-25)A,U(-27)C] moderately reduced splicing at the permissive temperature and sharply inhibited splicing at the originally nonpermissive temperature, arguing that MuSVts110 splicing thermosensitivity depends on a suboptimal BP-U2 small nuclear RNA interaction. This conclusion was supported by results indicating that lengthening the short MuSVts110 polypyrimidine tract and altering its uridine content doubled splicing efficiency at permissive temperatures and nearly abrogated splicing thermosensitivity. In vitro splicing experiments showed that MuSVts110 G(-25)A RNA intermediates were far more efficiently ligated than RNAs carrying the wild-type BP, the G(-25)A,U (-27)C BP, or the extended polypyrimidine tract. The efficiency of ligation in vitro roughly paralleled splicing efficiency in vivo [G(-25)A BP > extended polypyrimidine tract > G(-25)A,U(-27)C BP > wild-type BP]. These results suggest that MuSVts110 RNA splicing is balanced by cis elements similar to those operating in other retroviruses and, in addition, that its splicing thermosensitivity is a response to the presence of multiple suboptimal splicing signals.

Amino Acid Sequence↗
PubMed1995

ImmunoMax. A maximized immunohistochemical method for the retrieval and enhancement of hidden antigens.

BACKGROUND: Since the introduction of mAb, immunohistochemistry has become an important tool in research and in surgical pathology. The most widely used fixative in routine histopathology is formaldehyde, and it has become the gold standard for morphologic tissue preservation. Although the molecular mechanism underlying the tissue fixation is not well understood, it has become clear that available immunoreactive Ag are progressively lost during the fixation process. For a long time, it was thought that formalin-sensitive Ag might be irreversibly destroyed during the fixation process. Although monoclonal anti-Ig Ab frequently worked inadequately, polyclonal anti-Ig Ab were shown to produce reproducible staining results. It thus appeared possible that most cellular Ag might not be irreversibly destroyed but only masked. EXPERIMENTAL DESIGN: Although some Ag may be retrieved under appropriate conditions, there might still be many for which available antigenic epitopes are still too sparse to be visualized, as observed for a large number of leukocyte differentiation Ag. One reliable approach to resolve this dilemma is the use of a combination of an optimized Ag retrieval system and a powerful immunohistochemical staining protocol introducing a biotin amplification step, in which signal amplification is accomplished by covalent deposition of biotin molecules. RESULTS: Cryostat and paraffin sections were stained with the avidin-biotin complex technique and, for comparison, with the new maximized immunohistochemical staining protocol, termed the ImmunoMax method. Each step was monitored to establish how effectively it enhanced the overall sensitivity. Although pretreatment with detergent, protease, a chaotropic substance, or microwave heating resulted in only moderately improved immunostaining, the biotinylated tyramine enhancement step proved to be the most efficient one, although the latter is not sufficient for many Ag when used without pretreatment steps. The combination of an Ag retrieval step with the biotinylated tyramine enhancement step resulted in a 100 to 10,000-fold boost in sensitivity without loss of specificity. CONCLUSIONS: With the ImmunoMax method, defined Ag can be reproducibly detected in formalin-fixed, paraffin-embedded tissues, and the sensitivity of the method is tremendously enhanced. Moreover, it also allows many previously unreactive or unsatisfactorily reactive Ag to be detected, as shown here for IgD, IgM, and CD7 with the use of mAb.

Antigens↗
PubMed1995

[Comparative study of umbilical artery Doppler velocimetry, antenatal fetal heart rate monitoring and umbilical artery blood-gas analysis in the prediction of neonatal outcome].

One hundred and fifteen term pregnancies (62 normal pregnancies, 53 high risk pregnancies) were observed by umbilical artery Doppler velocimetry (UmA S/D ratio) and antenatal fetal heart rate monitoring (NST), and 37 of them were also observed by umbilical artery blood-gas analysis at birth. We compared the effects of these three methods to predict the neonatal outcome. The standards of the neonatal poor outcome were 5-min Apgar score < or = 7 and/or a birth weight < 2500g (SGA). The results were: (1) The neonatal poor outcome were more frequently observed in the abnormal UmA S/D ratio (> or = 3.0) group and in the UmA pH < or = 7.2 group (P < 0.005, P < 0.025, respectively), but there was no significant difference between the NST reactive or nonreactive groups (P > 0.05); (2) The neonatal acidosis at birth was also associated with the abnormal UmA S/D ratio (> or = 3.0); (3) The sensitivities of UmA S/D ratio, UmA pH, NST to predict the 5-min Apgar score < or = 7 were 60.0%, 60.0%, 20.0% respectively; the specificities 84.6%, 81.3%, 81.8% respectively. And their sensitivies to predict SGA were 100.0%, 100.0%, 40.0% respectively; the specificities 86.4%, 80.0%, 82.7% respectively. Our data show that UmA S/D ratio and UmA pH are better than NST in the prediction of neonatal outcome, and the abnormal UmA S/D ratio is closely associated with neonatal acidosis at birth.

Apgar Score↗
PubMed1995

[The analysis of the causes and changes in maternal mortality in 42 years].

The causes and change of maternal death in this hospital from 1949 to 1990 was analyzed. The average maternal mortality of 42 years was 150.22/10(5) livebirths. The 42 years was divided into four periods which were 1949-1960, 1960-1970, 1971-1980 and 1981-1990. The results showed that the maternal mortality rate lowered from 365.31/10(5) livebirths in first period to 43.67/10(5) livebirths in the 4th period. The difference was markedly significant P < 0.01. The direct obstetric causes of maternal deaths in these periods were 30.00%, 23.81%, 25.00% and 55.56% respectively and increased in the 4th period. Obstetric hemorrhage (55.71%) pregnancy induced hypertension (31.43%) and preperal infection (11.43%) were the three main causes of maternal deaths in direct obstetric causes. Cardiac diseases (40.00%) was the leading cause in indirect causes.

Adult↗
PubMed1994

Isolation and characterization of Bsk, a growth factor receptor-like tyrosine kinase associated with the limbic system.

Neuronal degeneration has been shown to be involved in various neurological disorders. Growth/trophic factors and their receptors are known to be important for the regeneration and survival of neurons. We report here the molecular cloning of a receptor-like protein tyrosine kinase, bsk, (for brain specific kinase). Bsk is highly related to the eph/elk receptor-like kinase family members. Northern blot analysis shows that it is expressed specifically in the brain, with no expression detected in adult heart, spleen, lung, liver, skeletal muscle, and kidney. In situ hybridization analysis of adult mouse brain sections indicates that bsk is expressed at high levels in the hippocampus, tenia tecta, indusium griseum, and the piriform cortex, major components of the limbic system that are important for learning and memory. In addition, elevated levels of expression are found in other areas of the limbic system such as the amygdala, medial septum, and nucleus of the diagonal band, and in the olfactory bulb, which has close connections to the limbic system. The highest level of expression is found in the CA3 region of the hippocampus and the pyramidal cell layer of the piriform cortex. In 16.5 day mouse embryos, bsk is expressed predominantly in the primordial cortex of the telencephalon. An antibody against a C-terminal peptide of bsk recognized a 105 kD protein in the 16.5 day embryonic head extract. Our analysis shows that bsk is a growth factor receptor-like protein tyrosine kinase and that its greatest expression in the adult brain is associated with components of the limbic system.

Amino Acid Sequence↗
PubMed1994

Quantitation of prostate-specific acid phosphatase in prostate cancer: reproducibility and correlation with subjective grade.

In this study, we quantitatively evaluated the intensity and extent of prostate-specific acid phosphatase in immunocytochemically stained prostate carcinoma tissue sections by using a dual-wave-length-based image processing technique. Tissue sections were doubly stained in a standard way, i.e., prostate-specific acid phosphatase was immunocytochemically labeled by peroxidase-antiperoxidase (PAP) technique using diaminobenezidene (DAB) as the substrate and hematoxylin as a nuclear counterstain. Statistical analysis in this study indicated that the quantitative measures of the prostate-specific acid phosphatase staining (PAP-DAB) are reproducible. We found that the quantitative intensity was generally proportional to the subjective intensity (graded as 1 to 4+) of PAP-DAB. Although the quantitative extent measurements compared with the subjective estimates of the percentage of tumor showing staining with PAP-DAB had a similar tendency, there were significant overlaps between extent of tumor staining falling in the mid-ranges. Because subjective grading of immunocytochemical prostate-specific acid phosphatase has been thought to be a useful marker of tumor differentiation in patients with prostate carcinoma, we also evaluated the relationship of the quantitative measures of PAP-DAB staining to other predictors of patient outcome, including histologic grades (Gleason score and MD Anderson grading scheme) and clinical stage. We confirmed that quantitative intensity and extent of PAP-DAB staining were independent of histologic grades and stage, just as the subjective measures of intensity and extent were found to be. Possible explanations of this lack of correlation are discussed.

3,3'-Diaminobenzidine↗
PubMed1994

Further observations on the human maximum safe dietary selenium intake in a seleniferous area of China.

This report is a summarization of preliminary results from a study of dietary Se intake in a seleniferous area in order to determine safe levels. All patients have symptoms of toxicity: broken hair strands or various levels of nail damage. Finger-nail signs were the first symptoms used for diagnosis of selenosis in this work. Based upon the lowest blood-Se level of five subjects with persistent overt finger-nail signs of selenosis, it was found in 1986 that the individual marginal toxic blood Se level (LOAEL) and the corresponding Se intake were 1054 micrograms/L and 910 micrograms/d, respectively. To re-examine the clinical signs and blood Se levels of the five individuals and to see how the two are correlated, a study was conducted in July 1992 at the same location in the seleniferous area. The results showed that along with the absence of clinical signs, the average blood Se level had decreased from 1346 to 968 micrograms/L. The corresponding safe Se intake per day would be 819 +/- 126 micrograms (15 micrograms/kg B.W. or approximately 800 micrograms per day, which is suggested as the mean No Adverse Effect Level (NOAEL), and the lower limit of the 95% confidence interval, 600 micrograms per day would approximately the maximum individual safe Se intake. For safety, 400 micrograms is again proposed as the Maximum Safe Daily Dietary Se Intake. Problems inherent in this estimation have been discussed.

China↗
PubMed1994

Direct observation of the effect of autoreceptors on stimulated release of catecholamines from adrenal cells.

The direct effect of alpha 2-autoreceptors was studied by measuring the effects of piperoxan, an alpha 2-autoreceptor antagonist, and clonidine, an agonist on catecholamine exocytosis, from single bovine chromaffin cells in culture. Catecholamine release was elicited by stimulation with 100 microM nicotine and was monitored electrochemically with a carbon-fiber microelectrode placed adjacent to the cell. These electrodes allowed the number of exocytotic release events to be monitored and reported as total charge for release following a specific stimulus. Repeated stimulation with 100 microM nicotine showed that total release caused by the second exposure to nicotine was 32% of the first, and release caused by the third exposure to nicotine was 80% of the second. Total release of catecholamine increased significantly after application of 20 microM piperoxan relative to a control application of balanced salt solution. Application of 20 microM piperoxan alone did not cause release. After the cells were incubated in culture medium containing 20 microM clonidine, a significant decrease in nicotine-stimulated catecholamine release was observed. These results confirm that there are autoreceptors on chromaffin cells and, when relatively high levels of catecholamine are released, the catecholamine stimulates the alpha 2-autoreceptors, which inhibits subsequent release through a negative feedback mechanism. In addition to piperoxan, the sympathomimetic drug amphetamine also increases quantal release after application of nicotine. Amphetamine increases the extracellular concentration of catecholamine, and these data appear to indicate that at least part of the pharmacology of amphetamine might involve blocking catecholamine autoreceptors.

Adrenal Medulla↗
PubMed1993

Etiological investigation of acute post-transfusion non-A, non-B hepatitis in China.

The etiology of acute post-transfusion hepatitis (PTH) non-A, non-B (NANB) in China was investigated with the combination of advanced techniques, including a second generation of enzyme immunoassay for detection of the antibodies to hepatitis C virus (anti-HCV), a reverse transcription and nested polymerase chain reaction (RT-nPCR) for HCV RNA, and a PCR for hepatitis B virus DNA. Of the 57 patients who were diagnosed as acute PTH-NANB, 46 (80.7%) were positive for anti-HCV and 41 (71.9%) had HCV RNA. Combining together, 53 (93.0%) were seropositive for anti-HCV and/or HCV RNA. Surprisingly, 18 of these with HCV markers were also positive for HBV DNA, although they were negative for HBsAg, suggesting that a portion of the patients with acute PTH NANB were coinfected by both HCV and HBV. In addition, 4 (7%) of the patients with acute PTH-NANB had no detectable HCV and HBV markers with the use of the above-mentioned techniques. These results indicate that etiologic agents(s) other than HCV and HBV may also cause acute PTH-NANB or that the current techniques may still not be sensitive enough to detect trace levels of HCV and HBV markers.

Adolescent↗