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Biomedical subjects

Y Cao

Publications and source records attributed to Y Cao.

At least 379 records · Page 21Linked to original sources
PubMed1996

Quantitative analysis of serum neutralization of human immunodeficiency virus type 1 from subtypes A, B, C, D, E, F, and I: lack of direct correlation between neutralization serotypes and genetic subtypes and evidence for prevalent serum-dependent infectivity enhancement.

Human immunodeficiency virus type 1 (HIV-1) M group strains have been assigned to date to nine distinct genetic subtypes, designated A through I, according to phylogenetic analyses of nucleotide sequences of their env or gag genes. Whether there is any relationship between phylogenetic subtypes and the neutralization serotypes is not clear, yet defining the nature of any such relationship by mathematical means would be of major importance for the development of globally effective HIV-1 vaccines. We have therefore developed a quantitative method to analyze serum neutralization of HIV-1 isolates and to identify HIV-1 neutralization serotypes. This method involves calculations of the neutralization index, N(i), a newly defined parameter derived from plots generated from in vitro neutralization assays, calculations of pairwise serum-virus vector distances, and cluster analyses. We have applied this approach to analyze three independent neutralization matrices involving primary HIV-1 strains and sera from genetic subtypes A, B, C, D, E, F, and I. Detailed serum and HIV-1 isolate cluster analyses have shown that in general, the identified neutralization serotypes do not directly correlate with HIV-1 genetic subtypes. These results suggest that neutralization serotypes do not during natural HIV-1 infection are not governed by antibodies directed against simple epitopes within gp120 monomers. A significant proportion (28%) of 1,213 combinations of sera and HIV-1 isolates caused serum-dependent infectivity enhancement [negative N(i) values] rather than neutralization. We also noted that negative N(i) values tended to correlate better with certain HIV-1 isolates rather than with HIV-1-positive sera. Syncytium-inducing variants of HIV-1 were slightly more likely than non-syncytium-inducing variants to undergo serum-dependent infectivity enhancement, although the latter variants could clearly be susceptible to enhancement.

Amino Acids↗
PubMed1996

T1 alpha protein is developmentally regulated and expressed by alveolar type I cells, choroid plexus, and ciliary epithelia of adult rats.

T1 alpha is the first marker gene known to be expressed in the adult lung solely by the alveolar type I epithelial cell. Previous studies showed that T1 alpha transcripts are abundant in early rat embryos where they are found in the nervous system and in the foregut and certain of its derivatives including the primitive lung. By mid- to late gestation T1 alpha messenger RNA (mRNA) expression is lost from neural tissues but appears to increase in the lung throughout fetal life. To determine whether the T1 alpha transcripts are translated into protein, especially in early embryos which sometimes express transcripts that are translationally silent, we performed immunohistochemistry on embryos and fetal tissues and analyzed certain tissues by western blotting using a monoclonal antibody against T1 alpha protein. T1 alpha protein is present at all sites that have previously been shown to express the mRNA and at similar developmental stages. As estimated from western blots, T1 alpha protein abundance peaks at about fetal day 16 in the brain and decreases thereafter to a relative level in the adult that is lower than that of the neural tube of the day 13 embryo. Relative protein abundance in the lung is very low, although detectable, on embryonic day 13 but increases slowly until fetal day 20 when there is a dramatic increase. At the time of birth, restriction to the type I cell is not complete and therefore must occur during postnatal lung development. Immunostaining reveals additional sites of expression in fetal and adult rats that had not been clearly visualized in previous in situ hybridization studies. T1 alpha is present in mesonephric tubules and apparently in primitive germ cells but is not detectable in specific cells in the adult kidney, ovary, or testis. However, cells of the choroid plexus of the central nervous system and the ciliary epithelium of the eye express T1 alpha in both fetuses and adults. The well-known functions of these epithelia are to elaborate cerebrospinal fluid and aqueous humor respectively by processes of active ion transport and water fluxes, probably through the aquaporin 1 (channel-forming integral membrane protein [CHIP] 28). We speculate therefore that T1 alpha protein may modulate or participate in these types of cellular functions in the lung.

Age Factors↗
PubMed1996

Facial canal dehiscence: a report of 1,465 stapes operations.

We retrospectively reviewed 1,465 stapes operations for facial canal dehiscences. The incidence of facial canal dehiscence was found to be 11.4%. A facial canal dehiscence with protrusion of the facial nerve is more common than a dehiscence without protrusion. In addition, 3 cases (0.2%) had a herniation of the facial nerve. Our data suggests that heredity could be one of the factors associated with a facial canal dehiscence. If an operated ear shows a dehiscent facial canal, there is a 29% possibility that the contralateral ear also has a dehiscence. Bilaterality of facial canal dehiscence is, therefore, exceptional.

Facial Nerve↗
PubMed1996

[A randomized clinical trial for the evaluation of head and neck squamous cell carcinoma treating with traditional Chinese medicine]

This paper described the research design,research process and statistical analysis of randomized clinical trial by treatment with traditional Chinese medicine in patients with squamous cell carcinoma of the head and neck.At first we found there was no significant difference between treating group and contral group(P>0.05) using log-rank test on Kaplan-Meier survival curves. With further multivariate analysis Cox model and after adjusting for sex,age,legth of taking the assigned medication,grade of tumor differentiation and using of chemotherapy,the rate of tumor-related death for control group was significantly higher than that for treating group :hazards ratio estimate was 1.939(95% confidence interval 1.008-3.729,(P<0.05).The length of taking Chinese medicine was one of the most important prognostic factors(P<0.001).The results suggest that the prescribed medication contributed to the improved survival,and it was an independent prognostic factor.

Journal Article↗
PubMed1996

Preoperative reverse transcriptase polymerase chain reaction for prostate specific antigen predicts treatment failure following radical prostatectomy.

PURPOSE: We previously demonstrated than an enhanced reverse transcriptase-polymerase chain reaction assay for prostate specific antigen (PSA) can predict final pathological stage in radical prostatectomy patients. The potential role of the assay in predicting serum PSA recurrence after radical prostatectomy was explored. MATERIALS AND METHODS: We evaluated 100 radical prostatectomy candidates by reverse transcriptase polymerase chain reaction preoperatively, and status was compared to serum PSA, Gleason score and final pathological results. Potential surgical failure was defined as tumor at the surgical margin or extending into the seminal vesicle. Patients were monitored postoperatively by serum PSA every 4 months. Kaplan-Meier analysis was used to evaluate the correlation between reverse transcriptase polymerase chain reaction and disease recurrence, defined as a PSA of 0.2 ng/ml. or greater. RESULTS: Enhanced reverse transcriptase polymerase chain reaction for PSA had a stronger correlation with potential surgical failure than preoperative serum PSA or Gleason score (relative risks 15.2, 5.9 and 3.2, respectively). The correlation between these modalities and PSA recurrence was evaluated during a mean followup of 13.6 months (range 5 to 26). Of 36 patients with positive reverse transcriptase polymerase chain reactions 9 had failure by PSA compared to 3 of 64 (4.7%) with negative polymerase chain reactions (p<0.0286). The relative risk for failure by reverse transcriptase polymerase chain reaction was 3.6. Gleason score and serum PSA had higher correlations with postoperative PSA elevations (relative risk 13.2 and 7.6, respectively). A Cox regression analysis model demonstrated that reverse transcriptase polymerase chain reaction for PSA can be used in conjunction with Gleason score and provides statistically significant risk information. CONCLUSIONS: Enhanced reverse transcriptase polymerase chain reaction for PSA is a statistically significant predictor of potential failure by pathological analysis and of disease recurrence by PSA. Longer followup data are required to define further the role of the assay in the management of patients with prostate cancer.

Aged↗
PubMed1996

[Latency of Epstein-Barr virus and its relationship to nasopharyngeal carcinomas].

Non-radioactive in situ hybridization and image analysis were used to study the distribution of Epstein-Barr virus (EBV) DNA and expression of the EBV latent genes, BNLF1, and BamH1 W sequence, in biopsy specimens of nasopharyngeal carcinoma (NPC) and chronic nasopharyngitis. The results showed that the high copy numbers of EBV genome and the expression of BamH1 W sequence, which was related to the transcription of EBV nuclear antigen 1 (EBNA 1) and the initiation of viral replication, occurred almost simultaneously in all poorly- or un-differentiated NPC. Furthermore, latent membrane protein (LMP) mRNA was expressed even in the nasopharyngeal epithelium with atypical hyperplasia. These results suggested that enormous replication of EBV episomes occurred with the progression of NPC and might be resulted from the activation of the viral promoter in the poorly- or un-differentiated stage of NPC. The inappropriate expression of LMP might be responsible for the proliferation and de-differentiation of nasopharyngeal epithelium.

Carcinoma, Squamous Cell↗
PubMed1996

[Ventilation effects of added jet air flows in different directions during expiratory phase on dogs with steam inhalation injury].

Nine dogs injured by inhaling steam were subjected to high frequency jet ventilation. Jet airflows of different directions were added during the expiratory phase, and their effects on respiration, circulation and improvment in ventilation efficiency of dogs with inhalation injury were compared, and the assessment of the mechanism of high frequency two-way jet ventilation in the trachea was made. According to the direction of added airflow during expiratory phase, the animal models were classified into three groups: Model A, the control group, without any added airflow; Model B, airflow opposite to the direction of ventilation was added; Model C, airflow of the same direction was added. The results showed: 1. Model B, with its CO2 elimination (Vco2) increased significantly (P < 0.01) and PaCO2 decreased significantly (P < 0.01), was preferable to Model A. This might be due to the reduction of dead space. 2. Model C, although there was slightly reduced anatomical and physiological dead space as compared with model A, showed worse ventilation effects. The mechanism was probably related to increase in PEEP (from 0.20 +/- 0.10 to 0.59 +/- 0.08 kPa) and FRC (from 433 +/- 59 to 504 +/- 7.0 ml). It is suggested that high frequency two-way jet ventilation is preferable for the treatment of inhalation injury with type 1 respiratory failure rather than high frequency ventilation with PEEP.

Animals↗
PubMed1996

[The hepatitis A virus isolated and adapted in human diploid fibroblast cells (KMB17)].

Three hepatitis A virus (HAV) strains (L8, H32 and H52) were isolated from stool specimens of hepatitis A patients during an epidemic in 1988 in Shanghai and were adapted to grow in human diploid fibroblast cell strain (KMB17). The strains were serially carried through 10 passages in KMB17. The infectious titrations of these virus strains cultured for 28 days at the 10th passage were high up to 7.0-7.75 log TCID50/ml. The maximum virus yields occured in the 28th day after infection. Immune electronic microscopic studies revealed that the viral particles were 27-30 nm in diameter. The strains were neutralized by specific anti-HAV serum. Special fluorescent stained particles were observed clearly in the infected cellular plasma by direct IF. The above data suggest that the three strains are HAV and may be useful for further study.

Cell Line↗
PubMed1996

[Experimental studies of high frequency jet ventilation improved by enhancing expiratory turbulence].

OBJECTIVE: To improve the effect on CO2 elimination during high frequency jet ventilation by enhancing expiratory turbulence. METHODS: Nine healthy dogs with steam-induced type I respiratory failure were basically applied with high frequency jet ventilation (HFJV), and high frequency two-way jet ventilation (HFTJV), HFJV combined with thoracicoabdominal compression (HFJV+TAC), and HFJV combined with thoracicoabdominal compression-decompression (HFJV+ TACD) randomly for 30 min, respectively. The parameters were determined and the Reynolds numbers (NR) were calculated. RESULTS: Reynolds numbers were more than 3000 in all patterns, suggesting that the airflow was turbulent. Expiratory Na was higher. The NR of the latter three patterns was more significantly higher than that of HFJV (P < 0.01). CO2 elimination was 126, 111, 137 ml. min-1 in the latter three patterns, respectively and significant (P < 0.05) or very significant (P < 0.01) compared with 98.0 ml.min-1 in HFJV. Corresponding changes occurred in PaCO2. NO significant differences (P > 0.05) were observed in hemodynamic parameters. CONCLUSION: HFJV combined with inverse jet or thoracicoabdominal compression or decompression on expiratory phase could enhance expiratory turbulence and facilitate CO2 elimination in 9 dogs with steam-induced type I respiratory failure.

Animals↗
PubMed1996

[Experimental study of circulatory dynamics following inhalation injury in dogs].

Early changes in respiratory and circulatory dynamics before and after steam-inhalation injury were made in a dog model were studied. The results showed that the resistance of the respiratory system was significantly higher 3 hours and 4 hours post injury than that before injury (P < 0.05), the compliances of both the lung 4 hours post-injury and the respiratory system 3 hours psot-injury significantly decreased (P < 0.05), and the heart rate markedly lowered (P < 0.01), and the cardiac output also decreased (P < 0.05) 2 hours after injury. It is suggested that the early changes in the respiratory and circulatory dynamics may be used as markers for the diagnosis and treatment of the inhalation injury.

Airway Resistance↗
PubMed1995

gro-beta, a -C-X-C- chemokine, is an angiogenesis inhibitor that suppresses the growth of Lewis lung carcinoma in mice.

We have found that two chemokines, recombinant gro-alpha and gro-beta, specifically inhibit growth factor-stimulated proliferation of capillary endothelial cells in a dose-dependent manner, whereas gro-gamma has no inhibitory effect. In vivo, gro-beta inhibits blood vessel formation in the chicken chorioallantoic membrane assay. It is sufficiently potent to effectively suppress basic fibroblast growth factor-induced corneal neovascularization after systemic administration in mice. Further, gro-beta significantly inhibits the growth of murine Lewis lung carcinoma in syngeneic C57B16/J and immunodeficient nude mice without toxicity. In vitro, Lewis lung carcinoma cells are completely insensitive to recombinant gro-beta at high concentrations that significantly inhibit endothelial cell proliferation. This finding supports the conclusion that gro-beta inhibits Lewis lung tumor growth by suppression of tumor-induced neovascularization.

Amino Acid Sequence↗
PubMed1995

A rapid non-selective method to generate quadromas by microelectrofusion.

A simple non-selective methodology was developed and standardized to generate desired hybrid-hybridoma or quadroma secreting bifunctional antibodies. This novel protocol is based on microelectrofusion on a meander chamber using a few hundred cells of each of the two parental hybridomas with no laborious drug selection procedures. Seeding approximately 10 cells per well in a 96-well microtitre plate after fusion in 200 microliters standard medium containing 20% FBS and 10% Origen growth factor generated positive quadromas secreting bispecific antibodies with good stability after the second reclone. Compared to the conventional PEG fusion and other methods this simple protocol is both rapid and economical. Generally, conventional methods to make quadromas and triomas require the introduction of drug selection markers into one or both of the parental cells, a procedure that could take 3-6 months. Utilizing the non-selective microelectrofusion method described here, we have generated several quadromas in a very short time. Further, such a protocol could also be potentially adopted to generate human hybridomas with few B cells isolated from peripheral blood lymphocytes enriched by antigen specific panning or affinity microelectrofusions.

Animals↗
PubMed1995

Expression of Thomsen-Friedenreich-related antigens in primary and metastatic colorectal carcinomas. A reevaluation.

BACKGROUND: Expression of the pancarcinoma Thomsen-Friedenreich (TF) carbohydrate antigen or, more correctly, hapten, in colorectal carcinomas is not generally agreed on. Furthermore, its suggested role in liver metastasis so far has not been substantiated by direct immunohistochemical evidence. METHODS: Cryostat sections from 52 primary tumors (20 with adjacent transitional mucosa), 22 liver metastases of colorectal carcinomas, and 17 samples of normal mucosae were examined immunohistologically with a panel of at least two monoclonal antibodies (mAbs) each to TF, to its precursor, Tn, and to sialosyl-Tn, among them two newly developed anti-TF mAbs. RESULTS: Of the primary colorectal carcinomas, 60% expressed TF. Staining was more intense with TF-alpha/beta-reactive than with exclusively TF-alpha- or TF-beta-reactive mAbs. Normal and transitional mucosae were negative. Liver metastases were positive for TF in a significantly higher percentage of cases (91%) than primary carcinomas. Patients with TF-positive primary tumors had a significantly higher risk to develop liver metastases compared with patients with TF-negative tumors (57% vs. 14%, respectively). Tn and sialosyl-Tn were expressed concomitantly in most primary (85%) and metastatic (95%) colorectal carcinomas. These antigens also were detected in transitional mucosae (Tn in 25%, sialosyl-Tn in 55% of cases). Normal mucosae were negative. CONCLUSIONS: These results prove unequivocally the presence of exposed TF epitopes in a majority of colorectal carcinomas in which both anomers of TF are expressed. These data further suggest that TF favors liver metastasis and that its expression in primary colorectal carcinomas is a significant risk factor for the development of liver metastasis.

Antibodies, Monoclonal↗
PubMed1995

Fibrinogen alpha genes: conservation of bipartite transcripts and carboxy-terminal-extended alpha subunits in vertebrates.

All three well-studied subunits of the clotting protein fibrinogen (alpha, beta, gamma) share N-terminal structural homologies, but until recently only the beta and gamma chains were recognized as having similar globular C-termini. With the discovery of an extra exon in the human fibrinogen alpha gene (exon VI), a minor form of the alpha subunit (alpha E) with an extended beta- and gamma-like C-terminus has been identified (Fu et al., Biochemistry 31, 11968, 1992). In the present study, the polymerase chain reaction has been used to identify sequences that encode counterparts to alpha E in chicken, rabbit, rat, and baboon. The basic six-exon structure of the fibrinogen alpha genes is shown to be conserved among mammals and birds, as are the intron positions. Bipartite transcripts--still bearing an intron prior to the last exon--are found among the products of the various vertebrate fibrinogen alpha genes. The last exon represents the largest conserved segment of the gene and, in each species examined, encodes exactly 236 amino acids. The C-termini of these alpha E chains align without a single gap and are between 76 and 99% identical. Since the exon VI-encoded domain of alpha E is as well conserved as the corresponding regions of the beta and gamma chains, it follows that it is equally important and that alpha E-fibrinogen plays a vital, if as-yet unrecognized physiological role.

Amino Acid Sequence↗
PubMed1995

Identification of strong modifications in cation selectivity in an Arabidopsis inward rectifying potassium channel by mutant selection in yeast.

The Arabidopsis thaliana cDNA, KAT1, encodes a hyperpolarization-activated K+ channel. In the present study, we utilized a combination of random site-directed mutagenesis, genetic screening in a potassium uptake-deficient yeast strain, and electrophysiological analysis in Xenopus oocytes to identify strong modifications in cation selectivity of the inward rectifying K+ channel KAT1. Threonine at position 256 was replaced by 11 other amino acid residues. Six of these mutated KAT1 cDNAs complemented a K+ uptake-deficient yeast strain at low concentrations of potassium. Among these, two mutants (T256D and T256G) showed a sensitivity of yeast growth toward high ammonium concentrations and a dramatic increase in current amplitudes of rubidium and ammonium ions relative to K+ by 39-72-fold. These single site mutations gave rise to Rb+- and NH4(+)-selective channels with Rb+ and NH4+ currents that were approximately 10-13-fold greater in amplitude than K+ currents, whereas the NH4+ to K+ current amplitude ratio of wild type KAT1 was 0.28. This strong conversion in cation specificity without loss of general selectivity exceeds those reported for other mutations in the pore domain of voltage-dependent K+ channels. Yeast growth was greatly impaired by sodium in two other mutants at this site (T256E and T256Q), which were blocked by millimolar sodium (K1/2 = 1.1 mM for T256E), although the wild type channel was not blocked by 110 mM sodium. Interestingly, the ability of yeast to grow in the presence of toxic cations correlated to biophysical properties of KAT1 mutants, illustrating the potential for qualitative K+ channel mutant selection in yeast. These data suggest that the size of the side chain of the amino acid at position 256 in KAT1 is important for enabling cation permeation and that this site plays a crucial role in determining the cation selectivity of hyperpolarization-activated potassium channels.

Amino Acid Sequence↗
PubMed1995

The site of action of neuronal acidic fibroblast growth factor is the organ of Corti of the rat cochlea.

Here we show that the mature cochlear neurons are a rich source of acidic fibroblast growth factor (aFGF), which is expressed in the neuronal circuitry consisting of afferent and efferent innervation. The site of action of neuronal aFGF is likely to reside in the organ of Corti, where one of the four known FGF receptor (FGFR) tyrosine kinases--namely, FGFR-3 mRNA--is expressed. Following acoustic overstimulation, known to cause damage to the organ of Corti, a rapid up-regulation of FGFR-3 is evident in this sensory epithelium, at both mRNA and protein levels. The present results provide in vivo evidence for aFGF being a sensory neuron-derived, anterogradely transported factor that may exert trophic effects on a peripheral target tissue. In this sensory system, aFGF, rather than being a neurotrophic factor, seems to promote maintenance of the integrity of the organ of Corti. In addition, aFGF, released from the traumatized nerve endings, may be one of the first signals initiating protective recovery and repair processes following damaging auditory stimuli.

Animals↗