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Biomedical subjects

Y Shao

Publications and source records attributed to Y Shao.

At least 145 records · Page 8Linked to original sources
PubMed1996

Effects of thyroid hormone on left ventricular performance and regulation of contractile and Ca(2+)-cycling proteins in the baboon. Implications for the force-frequency and relaxation-frequency relationships.

The transcriptional, posttranscriptional, and related functional effects of thyroid hormone on primate myocardium are poorly understood. Therefore, we studied the effects of thyroid hormone on sarcoplasmic reticulum (SR) Ca(2+)-cycling proteins and myosin heavy chain (MHC) composition at the steady state mRNA and protein level and associated alterations of left ventricular (LV) performance in 8 chronically instrumented baboons. The force-frequency and relaxation-frequency relations were assessed as the response of LV isovolumic contraction (dP/dtmax) and relaxation (Tau), respectively, to incremental atrial pacing. Both the heart rate at which dP/dtmax was maximal and Tau was minimal (critical heart rates) in response to pacing were increased significantly after thyroid hormone. Postmortem LV tissue from 5 thyroid-treated and 4 additional control baboons was assayed for steady state mRNA levels with cDNA probes to MHC isoforms and SR Ca(2+)-cycling proteins. Steady state SR Ca(2+)-ATPase and phospholamban mRNA increased in the hyperthyroid state, and alpha-MHC mRNA appeared de novo, whereas beta-MHC mRNA decreased. Western analysis (4 thyroid-treated and 4 control baboons) showed directionally similar changes in MHC isoforms and a slight increase in SR Ca(2+)-ATPase. In contrast, there was a statistically nonsignificant decrease in phospholamban protein, which resulted in a significant 40% decrease in the ratio of phospholamban to SR Ca(2+)-ATPase. Thus, thyroid hormone increases the transcription of Ca(2+)-cycling proteins and shifts MHC isoform expression in the primate LV. Our data suggest that both transcriptional and posttranslational mechanisms determine the levels of these proteins in the hyperthyroid primate heart and mediate, in part, the observed enhanced basal and frequency-dependent LV performance.

Animals↗
PubMed1996

[Correlation between ability of learning-memory and synaptosomal free [Ca2+]i in mice of different age].

In the present investigation, the behavior of learning and memory of 1-month and 6-month-old mice was studied by using Y-maze and one-trial passive avoidance response device. The synaptosomal free [Ca2+]i of four main brain regions (Hippocampus, Cerebral cortex, Cerebellum, Tectum of midbrain) of these mice were measured by fluorescent probe Ca2+ indicator Fura-2 and an AR-CM-MIC cation measurement system. The results showed that, in comparison with 1-month-old mice, the ability of discrimination learning and memory of 6-month-old ones were attenuated, and the synaptosomal free [Ca2+]i of hippocampus was increased.

Age Factors↗
PubMed1996

[Dynamic study of renal function with radioimmunoassay technique (RIA) in burn patients].

Alb, beta 2-m, IgG in serum and urine were determined in 52 burn patients (from January 1993 to December 1994) with RIA technique. The results revealed that there was no obvious connection between the area of burn and the alteration in these parameters (P > 0.05). Our findings indicated a positive correlation between the depth of burn and impairment in the renal function. The recovery of renal function was gradual, and that of glomerulus was earlier than renal tubules. Monitoring of renal function with RIA technique showed a higher sensitivity and accuracy than routine examinations, and it might play an important role in the treatment of burned patients in different periods.

Adolescent↗
PubMed1996

Pentapeptides from the roots of Aster tataricus.

Asterinin D and E, pentapeptides, have been isolated from the roots of Aster tataricus L.f. (Compositae, syn. Asteraceae, subtribe Asteroideae) and their structures have been elucidated on the basis of spectroscopic analysis, as well as chemical and enzymatic methods.

Amino Acid Sequence↗
PubMed1996

[Prognosis of patients with breast cancer related to the timing of operation during menstrual cycle: a report of 218 patients].

We have finished a retrospective study of 218 premenopausal patients who underwent primary surgery for operable breast carcinoma between March 1958 and December 1984. All these patients had available records of menstrual data and had been followed-up for more than 10 years. U-nivariate analysis showed that the menstrual timing of operation, as other known prognostic factors (tumor size, node status, histological grade, TNM classification, adjuvent systemic therapy, etc), had an influence on the patients' outcome. Multivariate analysis by Cox regression model indicated that disease-free rate and overall survival rate of patients operated during the periovulatory phase (days 7-20, 123 cases) were significantly superior to those during the perimenstrual phase (days 1-6 and 21-40, 95 cases) (P < 0.01). There were no significant differences in prognosis between patients who received their operations during the follicular phase (days 4-14, 96 cases) and those during the luteal phases (days 15-40, 122 cases) (P > 0.1). We suggest that the adequate timing of operation should be further determined by prospective, randomized clinical study.

Adult↗
PubMed1996

[Expression of CD44v mRNA and its clinical significance in colorectal carcinoma].

In order to study the correlation of the CD44v gene abnormal expression and splicing with the clinicopathologic features, the expression of CD44v mRNA from normal colorectal mucosa, adenomatous polypi (precancerous disease) and colorectal carcinoma was studied by RT-PCR and cDNA hybridization. The results showed that CD44v mRNA was expressed in 65 of 67 (97%) primary cancers, in 20 of 20 metastatic tumors (100%) and in 5 of 7 (71.4%) precancerous diseases, but was not expressed in all 15 normal colon mucosa specimens. Abnormally spliced, high molecular weight CD44v could be detected in 10 of 20 (50%) primary cancers and in 18 of 20 (90%) metastatic cancers. In 10 patients with high molecular weight CD44v, metastases were found in 8, while metastases were found in only 2 of 10 patients with low expression of CD44v mRNA in the primary cancers. The results suggest that the expression of CD44v is very common in colorectal carcinoma. CD44v mRNA might be an early marker of colorectal carcinoma and its high expression is suggestive of tumor metastasis.

Adult↗
PubMed1996

[Conservative treatment for early breast cancer].

68 Cases of early breast cancer were divided into local resection group (33 cases) and local resection plus axillary dissection group (35 cases). The 3-, 5- and 10-year survival rate of the two groups were 97.0%, 78.8%, 72.7% and 94.3%, 80.0%, 77.1% respectively; The metastasis rate of the two groups were 6.1%, 12.1%, 3.0% and 8.6%, 17.1%, 8.6% respectively; and the local recurrence rate of the two groups were 6.1%, 6.1%, 3.0%, and 5.7%, 5.7%, 2.9% respectively ( P > 0.05). The cosmetic satisfaction rate of the two groups were 60.6% and 65.7% respectively ( P > 0.05). Factors relating to cosmetic results were type of breast, operative incision, age and postoperative radiotherapy. Conservative operation for early breast cancer was safe, provided incision margin was 2 cm approximately 3 cm. In all patients mammplasty was performed after tumor resection, and contralateral breast were treated by mammominification when it was necessary.

Adenocarcinoma↗
PubMed1995

Prediction of tumor response to experimental radioimmunotherapy with 90Y in nude mice.

PURPOSE: To identify those factors that predict variability in tumor response to 90Y-radioimmunotherapy based on measurement of incorporated activity and physical dimensions of individual tumors and to apply the concept of effective dose to radioimmunotherapy. METHODS AND MATERIALS: Human colon carcinoma xenografts growing in nude mice were treated with anti-CEA antibodies labeled with 90Y directly or through a bispecific antibody/labeled hapten system. Tumor response was measured as the delay in growth to eight times the treatment volume. Noninvasive activity (based on bremsstrahlung radiation) and dimension measurements were made in these animals at several times after label injection. The following parameters were compared for their ability to predict individual tumor response: (a) injected activity, (b) injected activity times a factor based on average uptake as a function of volume, (c) in vivo activity per volume measured in each animal at a single time, (d) the integral over time of in vivo activity per volume in each animal, and (e) the minimum dose for each animal in a uniformly active ellipsoid whose total activity and dimensions varied over time the same as the tumor. RESULTS AND CONCLUSION: After correcting for differences in injected activity, two parameters account for much of the variability in tumor response. One of these is the general trend of larger tumors to take up less activity per volume. Additional variability can be accounted for by the in vivo activity per volume measurements. The minimum dose as introduced here is likely to be useful in estimating the biologically effective dose delivered by each treatment.

Animals↗
PubMed1995

Protein splicing: characterization of the aminosuccinimide residue at the carboxyl terminus of the excised intervening sequence.

Protein splicing is a self-catalyzed, posttranslational process which converts a precursor polypeptide into two new proteins by the excision of an internal polypeptide segment and the ligation of the flanking polypeptides. Evidence has been presented that protein splicing involves a branched intermediate, which is resolved into the two protein products by the cyclization of an asparagine residue to aminosuccinimide [Xu, M. Q., Comb, D. G., Paulus, H., Noren, C. J., Shao, Y., & Perler, F. (1994) EMBO J. 13, 5517-5522]. This report describes the chemical synthesis of a peptide with a C-terminal aminosuccinimide residue, corresponding to the putative C-terminus of the excised intervening sequence (intein) derived from the thermostable DNA polymerase of Pyrococcus species GB-D. The synthetic aminosuccinimide peptide was compared with the C-terminal cyanogen bromide peptide of the excised intein and found to be indistinguishable in terms of its chromatographic properties, high-resolution mass spectrum, and colorimetric assay involving reaction with hydroxylamine. This establishes definitively that protein splicing is accompanied by the cyclization of asparagine to yield an aminosuccinimide residue at the C-terminus of the excised intein and that this unusual residue is therefore a natural constituent of spliced proteins. The effects of pH and temperature on the stability of the synthetic aminosuccinimide peptide are described.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Direct measurement of intratumor dose-rate distributions in experimental xenografts treated with 90Y-labeled radioimmunotherapy.

PURPOSE: To measure, quantify, and evaluate the planar dose-rate distribution for human tumor xenografts implanted into mice that are treated with 90Y-labeled monoclonal antibodies or bispecific antibodies and 90Y-labeled haptens. METHODS AND MATERIALS: Twenty-five LS174T human colon carcinoma tumors grown subcutaneously in nude mice were treated with 90Y by either directly labeled ZCE025 or bispecific ECA001-DBX antibody systems. A simple, quick technique using GAF radiochromic medium determined the dose-rate distribution in a plane passing through the tumor center. The dose-rate distribution is generated from exposure to activity situated in one-half of the tumor (0.045 to 0.83 g). RESULTS: Planar dose-rate distributions were obtained from the tumor xenografts. Planar dose-rate histograms were computed along with the coefficients of variance and skewness of the distributions. The observed dose-rate distributions were quantitatively compared to those calculated for a uniformly distributed activity in a half-ellipsoid of the same volume and approximate shape as the tumor half. The observed dose-rate distributions were usually broader with a more positive coefficient of skewness than the dose-rate distributions calculated from the uniformly active half-ellipsoids. For 90Y, tumor shape plays an important role in determining the minimum tumor dose. For these tumors, the tumor minimum dose-rate is always observed along the edge, usually where the edge curvature is most convex. Larger tumors tended to have broader dose-rate distributions and more positive coefficients of skewness. Exceptions to this trend were associated with dose-rate maxima displaced from the central regions due to activity heterogeneity or tumor size greatly exceeding the range of emission. Calculations for dose rate from the conventional Medical Internal Radiation Dose (MIRD) formulation exceeded the average and minimum dose rate derived from radiochromic media. The coefficient of skewness became more positive for increasing time between injection and tumor excision, consistent with the activity evolving into a more uniform activity distribution. CONCLUSION: Using radiochromic media to measure the spatial dose-rate distribution is a valuable method for comparing the dose-rate heterogeneity among experimental tumor xenografts in animals treated with radiolabeled antibodies. Tumor size (relative to the particle range) and changes in activity distribution radiolabeled antibodies. Tumor size (relative to the particle range) and changes in activity distribution affect the dose-rate distribution that are reflected by changes in the coefficients of skewness and variation of the dose-rate area histogram. The increase in coefficients of variation and skewness with tumor size and time results from the size of the 90Y beta particle penetration range that either exceeds or is comparable to the tumor dimensions. The minimum dose rate is more dependent, relative to the average and the maximum dose rates, on the curvature of the tumor surface.

Animals↗
PubMed1995

Disparate effects of early pressure overload hypertrophy on velocity-dependent and force-dependent indices of ventricular performance in the conscious baboon.

BACKGROUND: The effects of early pressure overload on left ventricular (LV) chamber mechanics in the primate heart are poorly understood. METHODS AND RESULTS: To test the hypothesis that early LV pressure overload hypertrophy is associated with depression of velocity-dependent indices of LV systolic (LV dP/dt) and diastolic function (time constant of relaxation, tau) but unchanged systolic elastance (Ees), we studied six conscious baboons instrumented with LV micromanometers and LV dimension and wall thickness sonomicrometers. Loading conditions were altered by pharmacological angiotensin II generation both before and 12 weeks after producing renovascular hypertension (2 kidney, 1 clip). The LV systolic pressure (149 +/- 11 [SD] versus 114 +/- 5 mm Hg) and LV mass (125 +/- 25 versus 91 +/- 20 g) were greater 12 weeks after than before (both P < .05). Both Ees and Ees normalized for LV mass were similar before versus 12 weeks after (23.0 +/- 9.6 versus 22.3 +/- 9.8 mm Hg/mL and 26.5 +/- 14.5 versus 19.8 +/- 12.5 mm Hg/mL, respectively; both P = NS). At matched LV systolic and diastolic pressures, LV fractional shortening was similar (18.6 +/- 6.8% versus 21.6 +/- 4.9%), but the time constant of LV isovolumic relaxation was significantly longer (42.3 +/- 5.3 versus 31.4 +/- 7.0 ms, P < .05) and LV dP/dt and Vcf were significantly less (1891 +/- 352 versus 2342 +/- 284 mm Hg/s and 0.9 +/- 0.4 versus 1.1 +/- 0.3 circ/s, respectively; both P < .05) 12 weeks after than before. CONCLUSIONS: In conscious baboons with systemic arterial hypertension and early LV hypertrophy, there is depression of velocity-dependent indices of LV contraction and relaxation but unaltered force-dependent measures of contractility.

Animals↗
PubMed1995

Dietary menhaden oil enhances mitomycin C antitumor activity toward human mammary carcinoma MX-1.

In the present study, we investigated the effects of high levels of dietary fish oil on the growth of MX-1 human mammary carcinoma and its response to mitomycin C (MC) treatment in athymic mice. We found that high levels of dietary fish oil (20% menhaden oil + 5% corn oil, w/w) compared to a control diet (5% corn oil, w/w) not only lowered the tumor growth rate, but also increased the tumor response to MC treatment. We also found that high levels of dietary fish oil significantly increased the activities of tumor xanthine oxidase and DT-diaphorase, which are proposed to be involved in the bioreductive activation of MC. Since menhaden oil is highly unsaturated, its intake caused a significant increase in the degree of fatty acid unsaturation in tumor membrane phospholipids. This alteration in tumor membrane phospholipids made the tumor more susceptible to oxidative stress, as indicated by the increased levels of both endogenous lipid peroxidation and protein oxidation after feeding the host animals the menhaden oil diet. In addition, the tumor antioxidant enzyme activities, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPOx), and glutathione S-transferase peroxidase (GSTPx), were all significantly enhanced by feeding a diet high in fish oil. MC treatment caused further increases in tumor lipid peroxidation and protein oxidation, as well as in the activities of CAT, SOD, GPOx, and GSTPx, suggesting that MC causes oxidative stress in this tumor model which is exacerbated by feeding a diet high in menhaden oil. Thus, feeding a diet rich in menhaden oil decreased the growth of human mammary carcinoma MX-1, increased its responsiveness to MC, and increased its susceptibility to endogenous and MC-induced oxidative stress, and increased the tumor activities of two enzymes proposed to be involved in the bioactivation of MC, that is, DT-diaphorase and xanthine oxidase. These findings support a role of these two enzymes in the bioactivating of MC and indicate that the type of dietary fat may be important in tumor response to therapy.

Animals↗
PubMed1995

Glycosides from Aster yunnanensis.

A new oleanane-type triterpene saponin named asteryunnanoside E and a new acetylene glycoside named asteryunnanoside I have been isolated from the roots of Aster yunnanensis, and their structures elucidated as 3-O-beta-D-glucopyranosyl-bayogenin-28-O-beta-D- glucopyranosyl-(1-->2)-beta-D-glucopyranoside and 2Z,8E-decadiene-4,6-diyn-1-O-beta-D-glucopyranos yl-(1-->2)-beta-D- glucopyranoside by means of 1D and 2D NMR techniques (COSY, HETCOR, COLOC, HOHAHA and ROESY) and chemical transformations.

Carbohydrate Conformation↗
PubMed1995

Triterpenoid saponins from Aster batangensis.

Four novel triterpenoid saponins named asterbatanoside F, G, H and I were isolated from the roots of Aster batangensis and their structures elucidated as 3-O-beta-D-glucopyranosyl-23-O-acetyl-bayogenin-28-O-beta-D-glu cop yranosyl- (1-->6)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-bayogenin-28-O-beta-D-glucopyranosyl-(1- ->6)-[alpha-f1p4amnopyranosyl-(1-->2)]-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl- (1-->3)-beta-D-glucopyranosyl-bayogenin-28-O-beta-D-glucopyranosyl -(1-->6)-beta-D-glucopyranoside, and 3-O-beta-D-glucopyranosyl-(1-->3)-beta-D- glucopyranosyl-23-O-acetyl-bayogenin-28-O-beta-D-glucopyranosyl-(1 -->6)-beta-D- glucopyranoside by means of spectral data, especially NMR including COSY, HETCOR, COLOC, HOHAHA, ROESY and selective INEPT techniques, and chemical evidence.

Carbohydrate Sequence↗
PubMed1995

Triterpene saponins from Aster yunnanensis.

Four new triterpene saponins, asteryunnanosides A, B, C and D, have been isolated from Aster yunnanensis and their structures deduced as 2 alpha,3 beta,23-trihydroxyolean-12-en-28-oic acid-28-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside, 2 alpha,3 beta,23-trihydroxyolean-12-en-28-oic acid-28-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside, 2 alpha,3 beta-dihydroxyolean-12-en-28-oic acid-28-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside and 2 alpha,3 beta-dihydroxyolean-12-en-28-oic acid-28-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside, respectively, by means of spectral and chemical data.

Carbohydrate Conformation↗