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Biomedical subjects

Y Cai

Publications and source records attributed to Y Cai.

At least 163 records · Page 9Linked to original sources
PubMed1998

Somatic inactivation of Pkd2 results in polycystic kidney disease.

Germline mutations in PKD2 cause autosomal dominant polycystic kidney disease. We have introduced a mutant exon 1 in tandem with the wild-type exon 1 at the mouse Pkd2 locus. This is an unstable allele that undergoes somatic inactivation by intragenic homologous recombination to produce a true null allele. Mice heterozygous and homozygous for this mutation, as well as Pkd+/- mice, develop polycystic kidney and liver lesions that are indistinguishable from the human phenotype. In all cases, renal cysts arise from renal tubular cells that lose the capacity to produce Pkd2 protein. Somatic loss of Pkd2 expression is both necessary and sufficient for renal cyst formation in ADPKD, suggesting that PKD2 occurs by a cellular recessive mechanism.

Alleles↗
PubMed1998

Retinoic acid differentially regulates retinoic acid receptor-mediated pathways in the Hep3B cell line.

Retinoic acid (RA) up-regulates retinoic acid receptor beta (RAR beta) gene expression in a variety of cell lines. Whether up-regulation of the RAR beta gene reflects increased activity in a RAR beta-mediated biological process is unclear since RAR beta tends to heterodimerize with retinoid x receptor (RXR). In F9 teratocarcinoma cell line, RA-induced differentiation is accompanied by increased expression of the RAR beta, RXR alpha, and alpha-fetoprotein (AFP) genes. Previously, we have shown that the RA-mediated regulation of the AFP gene is through RXR alpha homodimers. In contrast to F9 cells, Hep3B is unique in that the AFP gene is down-regulated by RA in a manner reminiscent of down-regulation of AFP in postfetal liver. In this paper, we have examined the RA-mediated regulation of the RAR, RXR, peroxisome proliferator-activated receptor (PPAR), and AFP genes in Hep3B cells. RA induced the expression of RAR alpha, beta, and gamma mRNA in Hep3B cells. However, the expression of RXR alpha mRNA was down-regulated, and the levels of RXR beta and RXR gamma mRNA remained unchanged after RA treatment. In addition, the expression of the PPAR alpha, beta, and gamma genes was also unchanged. Gel retardation assays demonstrated that RA decreased the overall binding of nuclear receptors to the RA and PPAR response elements. By super-shift assays using specific anti-RAR and -RXR antibodies, RA treatment decreased the amount of RXR alpha while increasing the amount RAR beta bound to retinoic acid response element-DR1 (direct repeat with spacer of one nucleotide), indicating the levels of RAR/RXR heterodimer, RXR/RXR homodimer, or RAR/RAR homodimers were altered upon RA treatment of Hep3B cells. In addition, the RA-mediated reduction of RXR alpha in part results in down-regulation of the AFP gene. Our data indicates that RA exerts its effects by differentially regulating its own receptor gene expression.

Animals↗
PubMed1998

Real-time interactive simulator for percutaneous coronary revascularization procedures.

This article describes the simulation of real-time catheter navigation in our interactive interventional cardiology simulation system (ICard). ICard is designed to enable medical students or physicians to familiarize themselves with the techniques of interventional catheterization procedures. The ICard software provides three-dimensional (3-D) views of the blood vessels and fluoroscopic images for real-time visualization of the catheter position. The 3-D human vasculature is built from various image data sets and is represented with a central line hierarchy model. Navigation of the catheter and guide wire and their interaction with blood vessels are implemented by applying the finite element method. Physical modeling that features the elasticity of the catheter and guide wire was developed to provide a realistic simulation of catheterization procedures. An electromechanical device was also developed in the system, allowing physical manipulation of catheter and guide wire movements. ICard can be used for training and design of equipment for interventional cardiology and may be further extended for pretreatment planning.

Computer Simulation↗
PubMed1998

Airway inflammation after treatment with aerosolized deoxyribonuclease in cystic fibrosis.

Recombinant human deoxyribonuclease (rhDNase) has been shown to reduce sputum viscoelasticity and to improve lung function in patients with cystic fibrosis (CF). The aim of this study was to determine whether airway inflammation would decrease after administration of rhDNase. Twenty patients with CF and chronic suppurative lung disease inhaled 2.5 mg of rhDNase daily for 1 month. Before and after the 1-month trial, lung function was measured and sputum was obtained, either after spontaneous expectoration or after sputum induction with hypertonic saline. Sputum total cell and differential counts were measured using techniques previously described. The mean age of the patients was 16.8 years (range, 6.7-27.5). After 1 month of rhDNase, mean FEV1 increased from a baseline of 62.3% predicted to 70.8% (P= 0.02, paired t test); and FVC increased from 74.4% to 83.9% predicted (P=0.007). No significant differences were found in sputum cytology before or after rhDNase (median total cell counts 16.0 x 10(6)/ml vs. 19.3 x 10(6)/ml, P=0.68). Thirteen patients had a 10% or greater increase in FEV1 after rhDNase (responders). Initial lung function was less in responders than in nonresponders (53.5% vs. 78.6%, P=0.007). There was no significant change in total cell count and neutrophil count after rhDNase in either responders or nonresponders. We conclude that airway inflammation, as measured by total cell counts in sputum, was a prominent feature in cystic fibrosis, and neutrophils were the dominant inflammatory cells. Although the administration of rhDNase resulted in significant improvements in FEV1, there was no evidence of accompanying changes in airway inflammation.

Administration, Inhalation↗
PubMed1998

In vitro 2,3,7,8-tetrachlorodibenzo-p-dioxin interference with the anterior pituitary hormone adrenocorticortropin.

Treatment of male Sprague-Dawley rats with a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to increase serum adrenocorticotropin (ACTH) and decrease serum corticosterone. The present in vitro study was designed to assess whether TCDD has a direct effect on the anterior pituitary under basal and stimulated conditions. Primary anterior pituitary cell cultures were prepared from normal 180- to 220-g male Sprague-Dawley rats and the cultures treated with 10(-9)-10(-19) M TCDD. Maximal secretion of ACTH occurred between 10(-11) and 10(-15) M TCDD for both medium (2-fold) and intracellular (1.5-fold) concentrations after 24 h TCDD exposure. TCDD treatment also caused an early (6 h) and persistent (10 days) increase in basal medium (1.4- to 2.8-fold) and intracellular (1.1- to 1.7-fold) ACTH concentrations. However, while stimulation with corticotropin-releasing hormone (CRH) increased intracellular ACTH 1.5- to 1.7-fold in pituitary cells treated for 24 h with 10(-9)-10(-13) M TCDD, ACTH secreted into the media was decreased by 30-50% compared with controls. Lastly, the secretagogue arginine-8-vaso-pressin (AVP), did not increase the amount of ACTH secreted above levels observed with basal TCDD exposure. From this study, it appears that TCDD stimulates in vitro synthesis and secretion of ACTH by the anterior pituitary under basal conditions, but decreases the pituitary's responsiveness to CRH and AVP stimulation.

Adrenocorticotropic Hormone↗
PubMed1998

Influence of lactobacillus spp. from An inoculant and of weissella and leuconostoc spp. from forage crops on silage fermentation

Lactobacillus spp. from an inoculant and Weissella and Leuconostoc spp. from forage crops were characterized, and their influence on silage fermentation was studied. Forty-two lactic acid-producing cocci were obtained from forage crops and grasses. All isolates were gram-positive, catalase-negative cocci that produced gas from glucose, and produced more than 90% of their lactate in the D-isomer form. These isolates were divided into groups A and B by sugar fermentation patterns. Two representative strains from the two groups, FG 5 and FG 13, were assigned to the species Weissella paramesenteroides and Leuconostoc pseudomesenteroides, respectively, on the basis of DNA-DNA relatedness. Strains FG 5, FG 13, and SL 1 (Lactobacillus casei), isolated from a commercial inoculant, were used as additives to alfalfa and Italian ryegrass silage preparations. Lactic acid bacterium counts were higher in all additive-treated silages than in the control silage at an early stage of ensiling. During silage fermentation, inoculation with SL 1 more effectively inhibited the growth of aerobic bacteria and clostridia than inoculation with strain FG 5 or FG 13. SL 1-treated silages stored well. However, the control and FG 5- and FG 13-treated silages had a significantly (P < 0.05) higher pH and butyric acid and ammonia nitrogen contents and significantly (P < 0. 05) lower lactate content than SL 1-treated silage. Compared with the control silage, SL 1 treatments reduced the proportion of D-(-)-lactic acid, gas production, and dry matter loss in two kinds of silage, but the FG 5 and FG 13 treatments gave similar values in alfalfa silages and higher values (P < 0.05) in Italian ryegrass silage. The results confirmed that heterofermentative strains of W. paramesenteroides FG 5 and L. pseudomesenteroides FG 13 did not improve silage quality and may cause some fermentation loss.

Journal Article↗
PubMed1998

Persistence of sputum eosinophilia in children with controlled asthma when compared with healthy children.

We aimed to describe induced sputum cell counts in healthy nonasthmatic children, and to compare these to children with controlled and uncontrolled asthma. Following clinical assessment and spirometry, ultrasonically nebulized hypertonic saline was used to induce sputum from children with asthma (n=50) and without asthma (n=72). Sputum was dispersed and cell counts performed to yield total and differential cell counts. Specific stains were used for eosinophil and mast cell counts. All of the children with asthma were receiving inhaled and/or oral corticosteroids. Current asthma control was assessed in terms of symptoms and lung function. Children were classified as controlled on inhaled corticosteroids (no current symptoms, normal lung function n=15), current symptomatic asthma (n=16) and asthma exacerbation (n=11). It was found that eosinophils comprised a median 0.3% (interquartile range (IQR): 0, 1.05) of cells in sputum from healthy children. Sputum eosinophils (4.3% (IQR: 15, 14.1) p=0.0005) and epithelial cells (14% (IQR: 6, 19.4) p=0.0005) were significantly higher in children with asthma than in nonasthmatic children. Children whose asthma was controlled, as well as those with symptoms, had more sputum eosinophils and epithelial cells than the nonasthmatics. Mast cells were found in the sputum of only four of the 42 children with asthma. This study demonstrates that eosinophilic airway inflammation and epithelial damage can occur in children with asthma. Airway inflammation persists even in those children who are receiving inhaled corticosteroids, have normal lung function and good symptomatic control of their disease.

Administration, Inhalation↗
PubMed1998

Changes in populations of Listeria monocytogenes inoculated on packaged fresh-cut vegetables.

A variety of wholesale and retail packaged vegetables and salads were inoculated with a mixture of strains of Listeria monocytogenes and incubated at 4 and 10 degrees C. Whole rutabagas, butternut squash, and onions, as well as packaged Caesar salad, carrots, coleslaw mix, and stir-fry vegetables were purchased from local supermarkets in the Ottawa area. L. monocytogenes population levels remained constant on all fresh-cut vegetables stored at 4 degrees C for 9 days, except for carrots and butternut squash: counts of cell numbers declined on carrots and increased on the butternut squash. Fresh-cut vegetables stored at 10 degrees C, however, supported good growth of L. monocytogenes on all vegetables tested, except for chopped carrots, where the population decreased approximately 2 log units over a 9-day storage period. As in the situation with the produce stored at 4 degrees C, butternut squash supported the highest rate of cell growth. In addition, Caesar salad and coleslaw mix were kept at 25 degrees C for 1 or 2 days before subsequent storage at 4 or 10 degrees C to stimulate extreme temperature-abuse conditions. In Caesar salad stored at 4 degrees C, by day 6 an initial 24- and 48-h temperature abuse at 25 degrees C led to a 1.21- and 2.55-log-unit population increase, respectively, over the control. Similar increases were observed on Caesar salads stored at 10 degrees C. Compared to Caesar salad, coleslaw mix temperature-abused at 25 degrees C and then stored at 4 degrees C supported slightly greater increases in the population of L. monocytogenes, i.e., a 3.22- and 3.83-log-unit increase over the control for the 1- and 2-day abused samples, respectively. Coleslaw mix samples temperature-abused and then stored at 10 degrees, however, only showed log unit increases of 1.75 and 1.94, respectively, compared to the controls. These results point to the importance of strict temperature control to prevent or reduce the growth of L. monocytogenes cells on fresh-cut vegetables.

Colony Count, Microbial↗
PubMed1998

Characterization of a transferrin-independent iron uptake system in rat primary cultured cortical cells.

Multiple transferrin-independent iron uptake (Tf-IU) systems are known to be involved in the internalization of free iron salt in various mammalian cells. However, the characteristics of a Tf-IU system in cortical cells are not clear. In this study, we characterized the Tf-IU systems in both cortical and glial predominant (GP) cells from rat cerebral cortex to investigate the mechanism by which iron (Fe) or aluminum (Al) accumulates in the cerebral cortex. The Tf-IU systems in both cells were temperature- and Ca2*-dependent. The upregulation of Tf-IU system in GP cells by Fe- or Al-nitrilotriacetate (Fe- or AI-NTA) was 2- or 4-fold higher than that of cortical cells. Chemiluminescence analysis specific for O2- and 1O2 also showed that the production of active oxygen species in Fe-loading GP cells was twice higher than that of Fe-loading cortical cells. These results suggest the existence of Tf-IU systems in both cortical and GP cells similar to those of HeLa cells whose Tf-IU is metal- and Ca-2+ dependent, and that the glial cells contribute to metal accumulation in cerebral cortex. The present study may help to explain the pathogenesis of neurodegenerative disorders caused by inducing oxidative stress.

Aluminum↗
PubMed1998

[The clinical feature of laryngeal cancer in Yanbian area of China].

The pathogenic factors of laryngeal cancer in Yanbian area of China were investigated by analyzing the clinical characteristic of laryngeal cancer patients treated in Yanbian hospital from February 1981 to February 1992. The results showed that the peak period for the occurrence of this disease was at the ages between 50 and 69. The ratio of female patients to males was much lower than that found in Northeast Area of China. The onset of laryngeal cancer had been increasing since 1982 and remained high even in 1990s. The penetrating site was most frequently found in supraglottic portion, and the squamous cell carcinoma was the most common pathologic type. Laryngeal cancer was related to cigarette smoking to which the female patients were more sensitive than males. However, no definite reference was found between drinking and laryngeal cancer.

Adult↗
PubMed1998

[A model for exercise-induced asthma in guinea pigs with lipopolysaccharide and metyrapone].

OBJECTIVE: To investigate the relationship between airway inflammation and exercise-induced asthma (EIA), an experimental model for EIA in guinea pigs was developed. METHOD: 27 guinea pigs was divided into 4 groups. A) LPS + MET exercise group (n = 7) had been pretreated with lipopolysaccharide (LPS 1 mg/kg, i.p.) and metyrapone (MET 50 mg/kg, i.p.) on the first day. Then lung resistance (RL) and dynamic compliance (Cdyn) were measured before and after exercise on the fourth day. B) LPS + MET non exercise group (n = 6) that pretreated with LPS and MET had nonexercise on the 4th day. C) NS exercise group (n = 7) pretreated with normal saline (NS 1 mg/kg, i.p.) on the 1st day. RL and Cdyn were measured before and after exercise on the 4th day. D) NS nonexercise group (n = 7) that pretreated with NS had no exercise on the 4th day. RESULT: In LPS+MET exercise group RL increased and Cdyn reduced significantly after exercise. In another 3 control groups there were no such changes either in RL or in Cdyn. CONCLUSION: These observations suggest that the treatment with LPS and MET could make a model for exercise-induced asthma.

Airway Resistance↗
PubMed1998

[Chemical stability of salmon calcitonin (sCT) analogues in aqueous solution].

Calcitonin is a peptide hormone with 32 amino acids. Natural calcitonins are presumably quite unstable in solution and numerous analogues of calcitonin had been synthesized to improve the stability. In the present paper, we report the investigation of the chemical stability of salmon calcitonin (sCT) analogues [Val1, Ala7]sCT, [Val1, Ala7, Ala30]sCT and [D-Ala30]sCT in aqueous solutions by reversed phase high-performance liquid chromatography (RP-HPLC) and fast atom bombardment mass spectrometry (FAB-MS) methods. The degradation patterns of the sCT analogues showed a marked dependence on pH and temperature. Most of the degradation products in pH 9.0 solution of sCT and its analogues were identified by FAB-MS analysis. Results showed that the sCT analogues are more stable at pH 3.3 and pH 3.7 than at pH 6.0 and pH 9.0. Analogues without disulfide bridge [Val1, Ala7]sCT and [Val1, Ala7, Ala30]sCT showed higher chemical stability than sCT while [D-Ala30]sCT showed lower chemical stability than the native sCT.

Calcitonin↗
PubMed1998

[The development of a myocardial infarction monitoring system].

In this paper, the author will discuss the system design of one portable myocardial infarction monitoring system which possesses the functions of the general arrhythmia monitoring and the alarm & emergency of acute myocardial infarction (AMI). This system also can provide accurate real time ECG signal parameters for clinic diagnosis.

Equipment Design↗
PubMed1998

[Determination of polyamines in pyronaridine-sensitive and -resistant Plasmodium berghei-infected erythrocytes].

AIM: To understand the relationship between polyamine metabolism and pyronaridine resistance of malaria parasites. METHODS: Kunming strain mice weighing 18 g-22 g were inoculated intraperitoneally with Plasmodium berghei ANKA strain (pyronaridine-sensitive, PS), and P. berghei ANKA strain low and high pyronaridine resistant lines (PRA and PRB), respectively. Seven days after inoculation, blood samples were collected and WBC in the blood were removed by the method of chromatography using SE-cellulose and Sephadex G25 (1:2). After thin layer chromatography, the contents of three polyamines, i.e. putrescine(PTC), spermidine (SPD), and spermine(SPM) in normal and infected erythrocytes were determined with fluorescence spectrometer. The changes of polyamine level in PS and PRB infected erythrocytes of mice treated by a single oral dose of PND 5 and 10 mg/kg respectively were also observed. RESULTS: The contents of PTC, SPD and SPM in PS infected erythrocytes were 47.5 +/- 28.6, 97.7 +/- 34.0 and 81.7 +/- 23.8 nmol/10(9) RBC (n = 9), respectively, being 1.5, 3.5, and 6.6 times of those appeared in the normal RBC (32.0 +/- 9.9, 28.2 +/- 12.3, and 12.4 +/- 15.0 nmol/10(9) RBC, n = 9), respectively. The differences between two groups were significant. Interestingly, when mice infected with pyronaridine resistant line PRA and PRB, the contents of PTC, SPD and SPM in the infected erythrocytes increased to 187.7 +/- 139.9, 258.3 +/- 137.9 and 142.8 +/- 143.8 nmol/10(9) RBC (n = 18), and 345.5 +/- 223.0, 435.8 +/- 265.4 and 189.4 +/- 171.7 noml/10(9) RBC, respectively. Except for SPM, PTC and SPD in the PRA and PRB infected erythrocytes were significantly higher than those in the PS and PRA infected erythrocytes, respectively, being 3.9, 2.6 and 1.8, 1.7 times of those appeared in PS and PRA infected erythrocytes. In PND treated group, SPD and SPM contents of PS infected erythrocytes were decreased by 31.6% and 47.3% compared with non-treated group, but the polyamine level of PRB infected erythrocytes did not significantly change after PND administration. CONCLUSION: The resistance of P. berghei to PND is related to the alteration of polyamine metabolism in the malarial parasites.

Animals↗
PubMed1998

[Facial soft tissue features analysis of normal Han race adults in Guangdong Province using computer-assisted-photogrammetric-system].

Facial soft tissue profile features of 150 normal native adults of Guangdong Province were analysed using computer-assisted-photogrammetric-system, which contained parameters written by polar coordinate. The results indicated that normal native adults of Guangdong Han race showed sex and region difference in features of facial profile soft tissue, and those parameters written by polar coordinate were helpful in the further study and clinical therapy.

Adult↗
PubMed1998

[Comparing the diagnoses of pneumoconiosis made by computer and experts from X-ray films].

The results on the agreement between microcomputer and experts for the diagnosis of pneumoconiosis from X-ray films are presented in this paper. On a set of 200 films, the diagnoses made by the computer and by five experts were compared; From 100 films, the agreement rates were 83.5% for the normal/abnormal, 73.0% for the four categories of profusion and 70.5% for the four categories of pneumoconiosis. From 100 films, the rates of agreament between the computer and the basic-level consultation group were 86.0%, 82.0% and 63.0% respectively. From 300 films for screening pneumoconiosis, the rate of agreement between the computer and the experts was 89.3%. The results demonstrate that the automatic diagnosis by computer is closer to the diagnosis made by experts.

Diagnosis, Computer-Assisted↗