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Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 631 records · Page 35Linked to original sources
PubMed1997

Characterization of maize elongation factor 1A and its relationship to protein quality in the endosperm.

The protein synthesis elongation factor 1A (eEF1A) is a multifunctional protein in eukaryotic cells. In maize (Zea mays L.) endosperm eEF1A co-localizes with actin around protein bodies, and its accumulation is highly correlated with the protein-bound lysine (Lys) content. We purified eEF1A from maize kernels by ammonium sulfate precipitation, ion-exchange, and chromatofocusing. The identify of the purified protein was confirmed by microsequencing of an endoproteinase glutamic acid-C fragment and by its ability to bundle actin. Using purified eEF1A as a standard, we found that this protein contributes 0.4% of the total protein in W64A+ endosperm and approximately 1% of the protein in W64Ao2. Because eEF1A contains 10% Lys, it accounts for 2.2% of the total Lys in W64A+ and 2.3% of the Lys in W64Ao2. However, its concentration predicts 90% of the Lys found in endosperm proteins of both genotypes, indicating that eEF1A is a key component of the group of proteins that determines the nutritional quality of the grain. This notion is further supported by the fact that in floury2, another high-Lys mutant, the content of eEF1A increases with the dosage of the floury2 gene. These data provide the biochemical basis for further investigation of the relationship between eEF1A content and the nutritional quality of cereals.

Actins↗
PubMed1997

Positive correlations between cerebral protein synthesis rates and deep sleep in Macaca mulatta.

Local rates of cerebral protein synthesis (ICPSleu) were determined with the autoradiographic L-[1-14C]leucine method in seven awake and seven asleep, adult rhesus monkeys conditioned to sleep in a restraining chair in a darkened, ventilated chamber while EEG, EOG, and EMG were monitored. Prior to the period of measurement all animals slept for 1-4 h. Controls were awakened after at least one period of rapid-eye-movement (REM) sleep. Experimental animals were allowed to remain asleep, and they exhibited non-REM sleep for 71-99% of the experimental period. Statistically significant differences in ICPSleu between control and experimental animals were found in four of the 57 regions of brain examined, but these effects may have occurred by chance. In the sleeping animals, however, correlations between ICPSleu and percent time in deep sleep were positive in all regions and were statistically significant (P < or = 0.05) in 35 of the regions. When time in deep sleep was weighted for the integrated specific activity of leucine in grey matter, positive correlations were statistically significant (P < or = 0.05) in 18 regions in the experimental animals. These results suggest that rates of protein synthesis are increased in many regions of the brain during deep sleep compared with light sleep.

Animals↗
PubMed1997

Interlaboratory agreement among results of human papillomavirus type 16 enzyme-linked immunosorbent assays.

Serological assays for measuring antibodies to human papillomavirus type 16 (HPV-16) virus-like particles (VLPs) have become important epidemiologic tools in recent years. However, the interlaboratory replicability of these assays has not been assessed. In this investigation, three laboratories tested a panel of specimens obtained from two different groups: 265 subjects in a vulvar cancer case-control study and 107 healthy volunteer blood donors. Each laboratory used an enzyme-linked immunosorbent assay (ELISA), but no attempt was made to standardize assay procedures among the three laboratories. The data showed good day-to-day intralaboratory replicability in laboratory 1 (correlation coefficient, > or = 0.88) and good intra-assay variability in laboratory 3 (correlation coefficient, > or = 0.93). Interlaboratory correlations, likewise, ranged between 0.61 and 0.80 in both case-control study subjects and healthy blood donors, indicating that ELISA optical density (OD) values between laboratories were linearly related regardless of the population. Kappa coefficients (kappa), based on each laboratory's categorical interpretation of its results (as positive or negative), showed good agreement (kappa, > 0.6) in case-control study subjects and moderate agreement (kappa, > or = 0.4) in blood donors, a population that had few strongly positive sera. When OD values near seropositive cutoffs were treated as indeterminates, there was little discordance between laboratories in either population. The data suggest that each laboratory measured the same humoral immune response and that their HPV-16 VLP ELISAs performed similarly (Pearson correlations). Interlaboratory differences, however, probably due to reagents and procedures, were considerably greater than intralaboratory day-to-day variability. Interlaboratory agreement in determining seropositivity (kappa) could be improved by sharing positive and negative serum controls and by treating marginal results as indeterminate. As part of continuing cooperation to improve interlaboratory agreement, we are preparing bulk serum control specimens to be shared and made available to interested researchers.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

Transcriptional activation by p53 of the human type IV collagenase (gelatinase A or matrix metalloproteinase 2) promoter.

p53, a tumor suppressor and a transcription factor, has been shown to transcriptionally activate the expression of a number of important genes involved in the regulation of cell growth, DNA damage, angiogenesis, and apoptosis. In a computer search for other potential p53 target genes, we identified a perfect p53 binding site in the promoter of the human type IV collagenase (also called 72-kDa gelatinase or matrix metalloproteinase 2 [MMP-2]) gene. This p53 binding site was found to specifically bind to p53 protein in a gel shift assay. Transcription assays with luciferase reporters driven by the promoter or enhancer of the type IV collagenase gene revealed that (i) activation of the promoter activity is p53 binding site dependent in p53-positive cells but not in p53-negative cells and (ii) wild-type p53, but not p53 mutants commonly found in human cancers, transactivates luciferase expression driven by the type IV collagenase promoter as well as by a p53 site-containing enhancer element in the promoter. Significantly, expression of the endogenous type IV collagenase is also under the control of p53. Treatment of U2-OS cells, a wild-type p53-containing osteogenic sarcoma line, with a common p53 inducer, etoposide, induced p53 DNA binding and transactivation activities in a time-dependent manner. Induction of type IV collagenase expression followed the p53 activation pattern. No induction of type IV collagenase expression can be detected under the same experimental conditions in p53-negative Saos-2 cells. All these in vitro and in vivo assays strongly suggest that the type IV collagenase gene is a p53 target gene and that its expression is subject to p53 regulation. Our finding links p53 to a member of the MMP genes, a family of genes implicated in trophoblast implantation, wound healing, angiogenesis, arthritis, and tumor cell invasion. p53 may regulate these processes by upregulating expression of type IV collagenase.

Base Sequence↗
PubMed1997

A comprehensive model for right-left heart interaction under the influence of pericardium and baroreflex.

A phenomenological model of the cardiopulmonary circulation is developed with a focus on the interaction between the right heart and the left heart. The model predicts the hemodynamic consequences of changing circulatory parameters in terms of a broad spectrum of pressure and flow waveforms. Hemodynamics are characterized by use of an electrical analog incorporating mechanisms for transseptal pressure coupling, pericardial volume coupling, intrathoracic pressure, and baroreflex control of heart rate. Computer simulations are accomplished by numerically integrating 28 differential equations that contain nonlinear and time-varying coefficients. Validity of the model is supported by its accurate fit to clinical pressure and Doppler echocardiographic recordings. The model characterizes the hemodynamic waveforms for mitral stenosis, mitral regurgitation, left heart failure, right heart failure, cardiac tamponade, pulsus paradoxus, and the Valsalva maneuver. The wave shapes of pulmonary capillary wedge pressure under the above conditions are also accurately represented. Sensitivity analysis reveals that simulated hemodynamics are insensitive to most individual model parameters with the exception of afterload resistance, preload capacitances, intrathoracic pressure, contractility, and pericardial fluid volume. Baseline hemodynamics are minimally affected by transseptal coupling (up to 2%) and significantly affected by pericardial coupling (up to 20%). The model should be useful for quantitative studies of cardiopulmonary dynamics related to the right-left heart interaction under normal and disease conditions.

Animals↗
PubMed1997

Rates of local cerebral protein synthesis in fetal and neonatal sheep.

During gestation there is likely to be a constantly changing rate of protein synthesis in the brain that may exhibit regional specificity. With the use of the quantitative autoradiographic L-[1-(14)C]leucine method for the determination of local rates of leucine incorporation into cerebral protein (lCPS(Leu)), we have sought to characterize this important process. lCPS(Leu) was measured in nine fetal sheep (118-139 days gestational age) and five newborn lambs (1-5 days of age). In other experiments, the fraction of leucine in the precursor pool for protein synthesis in the brain derived from the arterial plasma was determined to be 0.57 +/- 0.04 (mean +/- SE) in one fetus and two lambs. This value was used in the calculation of lCPS(Leu) in 35 regions of the central nervous system, pineal body, and whole brain. Regardless of age, lCPS(Leu) was highest in the pineal body, brain stem, and hypothalamic nuclei and lowest in white matter. In sensorimotor cortex, corona radiata, pyramidal tracts, and whole brain, lCPS(Leu) was positively correlated with prenatal age (P < or = 0.05). These increases in lCPS(Leu) probably reflect myelination in the cerebrum, which is known to occur in late gestation.

Aging↗
PubMed1997

Aldose reductase gene expression is increased in diabetic nephropathy.

Aldose reductase gene expression is increased in insulin-dependent diabetes mellitus (IDDM) with nephropathy. Epidemiology studies in patients with IDDM and noninsulin-dependent diabetes mellitus (NIDDM) are consistent with the hypothesis that a genetic factor(s) influences the risk for kidney disease of diabetes mellitus (KDDM). Aldose reductase (AR), the rate-limiting enzyme in the polyol pathway, is a potential candidate gene product. The present study explored the hypothesis that AR gene expression is increased in peripheral blood mononuclear cells obtained from patients with KDDM. We studied four groups of volunteers: group I, normal subjects; group II, IDDM without nephropathy; group III, IDDM with kidney disease; and group IV, nondiabetics with kidney disease. AR messenger ribonucleic acid was measured by a ribonuclease protection assay. The results are expressed as the mean and 95% confidence interval (CI) of the AR/beta-actin messenger ribonucleic acid molar ratios (AR/beta-actin R). Among diabetics, the AR/beta-actin R was higher in group III (0.088; CI, 0.068-0.108) than in group I (0.045; CI, 0.033-0.057; P < 0.01). There were no significant differences in age, hemoglobin A1c, or duration of diabetes between groups II and III (P = NS). The AR/beta-actin R in group III was also higher than that in group II (0.045; CI, 0.030-0.060; P < 0.01) or group IV (0.019; CI, 0.011-0.027; P < 0.001). In contrast, among nondiabetics, AR/beta-actin R values were 2-fold lower in group IV than in group I (P < 0.01). The results of this study are consistent with the hypothesis that the degree of AR gene expression modulates the risk of KDDM.

Actins↗
PubMed1997

Reliability of radiographic grading of osteoarthritis of the hip and knee.

We review studies on the reliability of radiographic assessment of osteoarthritis of the hip and knee. Reliability studies were reported for 10 among 24 identified scores. In general, moderate to good agreement was found for overall scores and for separate grading of joint space narrowing of the hip and osteophytes of the knee in the majority of studies, while reliability tended to be lower for other radiographic features. Overall scores of the knee were more reliable than overall scores of the hip, and intra-rater-reliability was considerably higher than inter-rater-reliability in most instances. Comparison of reliability between scores can only be made with caution, given the difference in the design of reliability studies, particularly the different qualification of involved observers. The limits of existing knowledge on reliability of commonly used radiologic scores are outlined, and, proposals are made to overcome those limits in future studies.

Adult↗
PubMed1997

Multiplicity of antioxidant enzyme catalase in mouse liver cells.

Multiplicity of catalase activity has been observed in crude homogenates from the tissue and cell lines of mouse liver by ethanol/Triton X-100/heat treatment. The five enzymatically active catalase bands were designated as CAT1, CAT2, CAT3, CAT4, and CAT5 with a nondenatured molecular mass of 270kDa, 258kDa, 229kDa, 210kDa, or 197kDa, respectively. Cultured mouse liver cell lines, mouse liver tissue homogenate, and pure mouse liver catalase showed only one catalase band (CAT1) after ethanol/Triton X-100 treatment at 4 degrees C for 72 hr. The same treatment but incubated at 37 degrees C for 72 hr yielded three bands (CAT2, CAT4, CAT5) in normal cell line, only one band (CAT5) in MNNG-transformed and SV40-transformed cells, two bands (CAT1, CAT4) in mouse liver tissue homogenates, and two bands (CAT1, CAT3) in pure mouse liver catalase. These five catalase bands were further biochemically characterized. The CAT1, CAT2, and CAT3 are sensitive to heat (68 degrees C, 1 min), while CAT4 and CAT5 are rather heat resistant. The sensitivity to catalase inhibitors, such as aminotriazole, azide, or cyanide varies among the isoforms. Protease inhibitors could prevent the formation of CAT3 and CAT4, but not CAT5. Treatment with protease, however, removed all forms of catalase except CAT5. We conclude from this study that the appearance of different catalase bands is likely due to epigenetic modification of the protein, particularly proteolysis. The lowered catalase activity in transformed cells might also be attributable to the loss of two catalase isoforms.

Animals↗
PubMed1997

[Immunological features of steroid-resistant asthma].

OBJECTIVE: To investigate the pathogenesis and treatment of steroid-resistant (SR) asthma. METHODS: Changes of serum levels of soluble interleukin-2 receptor (sIL-2R) after oral prednisone (20 mg/d) therapy were observed, and the peripheral blood T cell inhibitory effects of dexamethasone, oxymatrine and thymus-derived immunoinhibiting agents were studied in vitro by lymphocyte proliferation assay. RESULTS: After prednisone therapy, serum levels of sIL-2R were significantly decreased in steroid-sensitive (SS) asthmatics (P < 0.001) but not in SR asthmatics (P > 0.5). The inhibitory effects of dexamethasone (10(-7) mol/L) on the proliferation of T cells from SR asthmatics were significantly less than those from SS asthmatics (P < 0.002). Oxymatrine and thymus-derived immuno-inhibiting agents inhibited T cell proliferation to a similar degree between SR and SS asthmatics. CONCLUSIONS: Persistent T cell activation due to relative unresponsiveness of T cells to glucocorticoids was a feature of SR asthma. The therapeutic benefit of immuno-inhibiting agents other than glucocorticoids in the management of SR asthma deserves further investigation.

Adult↗
PubMed1997

[Relationship of mdr1 gene expression and multidrug resistance of primary lung cancer].

OBJECTIVE: To evaluate the expression of mdr1 gene in various type of primary lung cancer. METHOD: A serious of 48 resected primary lung cancer tissues from 5 post-chemotherapy and 43 untreated patients and 33 adjacent normal lung tissues were analyzed for mdr1 gene by RT-PCR method. RESULTS: Fifteen of 48 tumor tissues were found to have overexpression of mdr1 gene, comprising 6 of 12 adenocarcinomas, 7 of 22 squamous cell carcinomas, 1 of 2 sarcocarcinomas, 1 of 12 small cell carcinomas. Of 5 post-chemotherapy specimens, only one case showed positive. In addition, 3 of 33 adjacent normal tissues also showed mdr1-positive. Overexpression of mdr1 gene did not be associated with tumor size, metastasis and stage of lung cancer. The relapse rate with mdr1-positive cases was higher (80%) than that with mdr1-negative (58%) by one year follow-up of these patients. CONCLUSION: Overexpression of mdr1 gene can be detected in untreated primary lung cancer, specially in non-small cell lung cancer and may be regarded as one poorly prognostic marker.

Adenocarcinoma↗
PubMed1997

[Pleural amyloidosis].

OBJECTIVE: To evaluate the clinical significance of systemic amyloidosis in the differential diagnosis of pleural effusion. METHOD: Retrospective analysis of the incidence and the characteristics of pleural effusion in systemic amyloidosis. RESULTS: Seven (47%) of 15 cases of systemic amyloidosis were complicated with pleural effusion, of them 4 cases were confirmed by positive Congo red stain of percutaneous pleural biopsies specimens. CONCLUSIONS: Systemic amyloidosis involving pleura was not rare. Pleural amyloidosis should be suspected in pleural effusion complicated by multiorgan disease. Percutaneous pleural biopsy with Congo red stain can confirm the diagnosis.

Adult↗
PubMed1997

[Clinical study of polymerase chain reaction technique in the diagnosis of bone tuberculosis].

OBJECTIVE: To evaluate the clinical value of polymerase chain reaction (PCR) technique in diagnosis of bone tuberculosis. METHODS: PCR, standard light-microscopy and standard culture technique were used to detect Mycobacterium tuberculosis in samples obtained from 60 patients with bone tuberculosis and 20 patients without bone tuberculosis. In the meantime, some factors affecting PCR result were analysed and methods to deal with them were discussed. RESULTS: In the group of 60 patients with bone tuberculosis, the positive rate was 83% in PCR technique, 3% in standard light-microscope technique and 7% in the standard culture technique. A statistically obvious difference was seen (P < 0.005). In the group of 20 patients without bone tuberculosis, 2 cases showed positive in PCR technique, none in the other methods. Specificity of PCR technique in a blind comparison study indicated 100%. The whole process of PCR amplification is fully automatic and can be finished within several hours, and the detection time is considerably reduced. CONCLUSIONS: PCR technique is a rapid, specific, sensitive and simple method for detection of mycobacterium tuberculosis in sample of bone tuberculosis, and it is of great value in the diagnosis of bone tuberculosis and differentiating bone tuberculosis from other bone diseases.

Adolescent↗
PubMed1997

[The expression of costimulating molecule B7.1 in lymphoma tissues].

OBJECTIVE: To study the expression of immuno-costimulating molecule B7.1 in lymphoma tissue and its part in immuno escape mechanism. METHODS: Using the RT-PCR and in situ hybridization (ISH) techniques, the expression of B7.1 molecule in 12 fresh and 23 paraffin embedded tissues were studied. RESULTS: (1) B7.1 mRNA transcription was detected in 10/12 lymphoma tissues by RT-PCR; (2) mRNA expression in 16/23 lymphoma tissues was detected by ISH with Dig-labelling B7.1 cDNA probe. Alternatively, a 450bp by transcript that was relevant to the normal B7.1 molecule was cloned and studied by RT-PCR and ISH respectively. CONCLUSION: More in depth studies should be performed on the relation between the transcript molecule and lymphoma and its effect on tumor immunity.

B7-1 Antigen↗
PubMed1997

[Surgical treatment of thoracic aortic aneurysm].

In 80 patients with thoracic aortic aneurysm were treated in our hospital, 62 were males and 18 females. Their age ranged from 20 to 73 years. The aneurysm lesions involved ascending aorta in 45 patients (Marfan's syndrome), aortic isthmus segment in 3, descending aortic aneurysm in 26, and thoraco-abdominal aneurysm in 3. Thoracic aortic aneurysm with dissecting aneurysm were found in 49. Stanford type A was present in 28 cases patients and type B in 21.61 patients underwent surgery including Bentall's operation in 35, Wheat's operation in 3, resection of discending aortic aneurysm with vascular prosthesis grafting in 14, and other types of operation in 9. Operative mortality rate was 6%. In the medically treatment group of patients, spontaneous rupture of the aneurysm occurred in 8. Among them, 5 died in hospital and another 2 at home. In this series of patients, Marfan's syndrome and dissecting aneurysm were the predominant pathological lesion. Since acute rupture of dissecting aneurysm is the main cause of death, surgical treatment should be immediate after the diagnosis is established. In the chronic dissecting aneurysm, early surgical treatment also should be considered.

Adult↗
PubMed1997

[In situ hybridization for interleukin 4 and interleukin 5 messenger RNA in asthma].

The actual mechanism by which a group of asthmatics were resistant to glucocorticoids therapy remains poorly understood. Previous in vitro studies suggested that the pattern of cytokine gene expression may play a role in determining steroid resistance. In the current study, we used the technique of mRNA in situ hybridization to examine whether peripheral blood mononuclear cells (PBMCs) from steroid-resistance (SR) asthmatics vs. Steroid-sensitive (SS) asthmatics expressed different patterns of cytokines, particularly after treatment with steroid. PBMCs from SR patients did not differ significantly from those of SS in terms of their number expressing Interleukin (IL)-4 mRNA and IL-5 mRNA (P > 0.05) by culture alone. There were no differences in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P > 0.05) between incubation in the absence and presence of dexamethasone (DXM, 10(-7) mol/L) in SR. SS patients had a significant dicrease in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P < 0.01) after culture in the presence of DXM as compared with incubation in media alone. Our findings indicate that SR asthma is associated with a dysregulation of the expression of the genes encoding for IL-4 and IL-5.

Adult↗
PubMed1997

[Analysis of antibiotic resistance and production of enterotoxin of MRSA].

100 separate Staphylococcus aureus (S. a) isolates at Beijing Jishuitan Hospital during Oct. 1994-Apr. 1995 were submitted to determine the proportion of methicillin-resistant S. a (MRSA) and susceptibility test to 12 antibiotics. MIC determinations of the antibiotics were performed. Also, production rate of enterotoxin was measured with RPLA method. The results showed that MRSA constituted 60% of all cultures. (Burns Dept. 67.4%, Internal Medicine 62.5%, Orthopedics Dept. 44%). The antibiotics with resistant rate of MRSA below 50% included vancomyin (3.3%), norvancomyin (5%) and amikacin (21.5%). The production rate of enterotoxin was 100% in MRSA and 20% in MSSA (methicillin-sensitive S. a). In this group, 35% of MRSA and 5% of MSSA produced more than 2 types of enterotoxin.

Anti-Bacterial Agents↗