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Biomedical subjects

Y Ma

Publications and source records attributed to Y Ma.

At least 361 records · Page 20Linked to original sources
PubMed1997

Iron-induced apoptosis in mouse renal proximal tubules after an injection of a renal carcinogen, iron-nitrilotriacetate.

Redox-active iron was demonstrated in mouse kidney by Timm's sulphide-silver staining after an injection of a renal carcinogen, iron-nitrilotriacetate (Fe-NTA). The iron was on the apical site of tubular epithelia of the renal proximal convoluted portion and in the tubules of the straight portion 30 min after the Fe-NTA injection. As the epithelial cells of the proximal tubules died, the iron disappeared in the dead cells and was stored in the cytoplasm of the more distal tubular epithelia. Biochemically, redox-active iron in the kidney rapidly increased to four times higher than the control 30 min after the Fe-NTA injection, then decreased to a plateau which was still higher than the control. Iron tightly stored in iron-storage proteins increased gradually by 3 h after the injection and then decreased at 5 h. The iron-induced free radical injuries, such as lipid peroxidation and protein oxidation, were demonstrated in the renal proximal tubules by histochemistry. The nuclei of the proximal tubular epithelia shrank and fragmented with the free radical injuries, and were positive for terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling. DNA ladder was demonstrated in the mice renal cortexes by agarose gel electrophoresis. It was elucidated that redox-active iron caused free radical injuries in the proximal tubules of mice kidneys after the injection of a renal carcinogenic iron (Fe-NTA) and induced the apoptosis of the proximal tubular epithelial cells.

Animals↗
PubMed1997

Functional expression of human mannan-binding proteins (MBPs) in human hepatoma cell lines infected by recombinant vaccinia virus: post-translational modification, molecular assembly, and differentiation of serum and liver MBP.

Human mannan-binding proteins (MBPs) occur in two forms, serum MBP (S-MBP) and liver MBP (L-MBP), both of which are synthesized in the liver from a single form of human MBP mRNA. To investigate further the mechanisms of post-translational modification, molecular assembly and differentiation of S-MBP and L-MBP in vitro, we expressed a full-length human MBP cDNA in three human hepatoma cell lines, using the vaccinia virus expression system. The expression of human MBP cDNA reproduced the native MBP differentiation of S-MBP and L-MBP in human hepatoma cells. The recombinant S-MBP was secreted into the medium, and the recombinant L-MBP retained in the cells. The former had the ability to activate the complement through the classical or lectin pathway but the latter did not. Furthermore, one notable difference between the two MBPs was the degree of oligomerization through interchain disulfide bonds between subunits. In addition, we showed that both S-MBP and L-MBP undergo hydroxylation of lysine and proline residues in collagen-like sequences, and that the hydroxylysine is glycosylated to form glucosylgalactosylhydroxylysine (GluGalHyl) and galactosylhydroxylysine (GalHyl). Hydroxylation was required for S-MBP to be assembled into large complexes, the apparent molecular sizes of which were estimated to be 200-1,300 kDa by SDS-PAGE under non-reducing conditions and gel filtration under non-denaturing conditions. The hydroxylation and subsequent glycosylation and oligomerization were inhibited by alpha,alpha'-dipyridyl, an inhibitor of collagen lysyl and prolyl hydroxylases. These results suggested that newly synthesized lectins undergo post-translational modifications unique to the two forms of MBP, S-MBP, and L-MBP, in human hepatocytes and hepatoma cells, and that the collagen-like domains of the MBPs play an important role in promoting molecular assembly.

Aged↗
PubMed1997

A longitudinal study of students' depression at one medical school.

PURPOSE: Using a standardized measure of depression at three assessment points, to examine depression in medical students during their training. METHOD: Students entering the University of Massachusetts Medical School in the fall in 1987, 1988, and 1989 were mailed a recruitment letter and baseline questionnaire four weeks prior to the start of classes. Subsequent assessments took place in the middles of year 2 and year 4 and included only the students who had participated in the baseline assessment. The baseline assessment included the Center for Epidemiological Studies Depression (CES-D) scale, the Bortner Type A Behavior scale, the Spielberger Trait Anger scale, and the Spielberger Anger Expression scale. In addition, the baseline package included a rating of perceived stress, a demographics questionnaire, and a social-life survey. The follow-up assessments included the CES-D scale, the rating of perceived stress level, and the social-life survey. Analytic methods used were univariate descriptive statistics, correlation, and multiple-linear-regression analyses, two-sample t-tests, analysis of variance, and chi-square tests. RESULTS: Of the initial pool of 300 students, 264 responded at the baseline assessment (88% response rate; 53% men); 171 of these participated in the year-2 assessment (65% response rate; 51% men), and 126 participated in the year-4 assessment (48% response rate; 48% men); a total of 99 students participated in all three assessments. CES-D scores > or =80th percentile were obtained for 18% of the entering students. This rose to 39% at year 2 and 31% at year 4 (p = .0001). No gender difference was found at baseline; however, the women experienced higher depression levels than did the men at year 2 (p = .004) and at year 4 (p = .04). Overall, gender and increases in perceived stress (from baseline to year 2) were significant predictors of increased CES-D scores (from baseline to year 2; p = .01 and p = .0001, respectively). For the women, increased perceived stress, angerin, and frequency of social contacts outside work/school were significant predictors of the magnitude of increases in CES-D scores (baseline to year 2; p = .0001, p = .02, and p = .03, respectively). CONCLUSION: These preliminary data support the view that, upon entering medical school, students' emotional status resembles that of the general population. However, the rise in depression scores and their persistence over time suggest that emotional distress during medical school is chronic and persistent rather than episodic. Also, the women had more significant increases in depression scores than did the men.

Analysis of Variance↗
PubMed1997

A pilot study of nadolol for overt aggression in developmentally delayed individuals.

OBJECTIVE: The aim of this preliminary pilot study was to investigate the safety and efficacy of open-label nadolol as an adjunctive pharmacological treatment for aggression and/or inattention/overactivity in a developmentally delayed child, adolescent, and young adult population. METHOD: Twelve subjects enrolled and completed (mean age 13.8 years, range 9 through 24) a 5-month, open, prospective protocol of nadolol (mean dose 109 mg, range 30 through 220 mg) with systematic baseline and outcome evaluations and weekly clinical assessment. RESULTS: All subjects were developmentally delayed and most were cognitively delayed. Ten subjects (83%) showed clinical improvement while receiving nadolol. Significant improvements were noted on observer-rated overt categorical aggression, severity of illness, and global impressions of improvement. No significant effects were found for inattention/overactivity. Nadolol was well tolerated, with few side effects. CONCLUSIONS: Overt categorical aggression presenting in developmentally delayed children, adolescents, and young adults may respond to nadolol treatment.

Adolescent↗
PubMed1997

A lipid trial tracking system.

A computerized tracking system was developed for the monitoring of recruitment and participant follow-up in the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH). In this study, over 8,000 subjects were screened, from which 1,278 were recruited over a two-year period. Subjects were randomized into three conditions (one is control, the other two with interventions) and followed for one year. Patient lipid profiles, dietary intakes, and psychosocial data were collected at baseline and after one year. The tracking system developed proved essential to the efficient management of WATCH and can be adapted for other research and nonresearch purposes.

Adult↗
PubMed1997

Chronically KIT-stimulated clonally-derived human mast cells show heterogeneity in different tissue microenvironments.

Human mast cell precursors arise in the bone marrow and circulate to different tissue microenvironments, where they develop distinct phenotypes that may be characterized by differential expression of the serine protease, chymase. The growth and development of mast cells is stimulated by mast cell growth factor, which is also known as kit ligand because its obligate receptor is KIT, the protein product of the c-KIT proto-oncogene. The in vivo influence of the KIT-kit ligand axis on the phenotype of human mast cells has not been determined. We used immunohistochemistry to detect in situ expression of tryptase and chymase by mast cells of a patient with urticaria pigmentosa and aggressive systemic mastocytosis, whose pathologic mast cells are clonally derived and chronically stimulated by KIT because they all contain the same point mutation causing constitutive activation of KIT. Mast cells in both spleen and skin expressed tryptase, but only in the skin did a majority of mast cells express chymase. We conclude that chronic stimulation of the KIT-kit ligand axis does not irrevocably commit mast cells to a chymase-positive or chymase-negative phenotype. These findings suggest that factors other than kit ligand predominate in determining mast cell phenotype.

Chymases↗
PubMed1997

Copper and iron-induced oxidative damage in non-tumor bearing LEC rats.

The copper and iron status in the liver of non-tumor bearing Long-Evans Cinnamon (LEC) rats (average age 17 months) was investigated. A direct quantitation of loosely-bound copper and iron was also investigated by using a chelating agent, nitrilotriacetic acid (NTA-chelatable free copper and iron). Besides the total copper and iron contents, the level of NTA-chelatable free copper was also higher in LEC rats than in LEA rats (P<0.05). But for the free iron level there was no significant difference between the two rat groups (P>0.05). The formation of thiobarbituric acid-reactive substances was higher in LEC rats than in LEA rats (P<0.01). The 4-hydroxy-2-nonenal (HNE)-modified proteins were also clearly demonstrated in LEC rat liver. The copper and iron which produced the most important effect in the process of oxidative damage in LEC rats could not be distinguished. Even though free copper, which could induce free radical injuries, was increased in LEC rats, neither tumor-induction nor preneoplastic lesions in the experimental LEC rats were observed. Therefore it is speculated that the elevation of a free iron is another important factor. Copper and iron, both important transition metals in the body, may participate in the induction of DNA damage and oncogenesis.

Animals↗
PubMed1997

Short wave diathermy for small spontaneous pneumothorax.

BACKGROUND: The treatment of small spontaneous pneumothorax can involve observation, tube thoracostomy, and surgery. This study evaluated the use of short wave diathermy as a method of accelerating the resolution of small pneumothoraces. METHODS: Twenty two patients with pneumothoraces of less than 30% by volume were randomly allocated to receive short wave diathermy for 25 minutes each day (n = 11) or observation with bed rest (n = 11). Chest radiographs were taken until the pneumothoraces resolved. RESULTS: There were no significant differences in the clinical characteristics between the two groups of patients. However, the mean (SD) rate of absorption was significantly higher with short wave diathermy than with observation (3.44 (0.94)% versus 1.57 (0.53)%, difference = 1.87, 95% confidence interval (CI) 1.19 to 2.55, p < 0.001). The time to complete reexpansion was shorter with short wave diathermy than with observation (6.86 (3.51) days versus 11.64 (3.61) days, difference = -4.78 days, 95% CI -7.95 to -1.61, p < 0.005). No evidence of damage resulting from short wave diathermy was found. CONCLUSIONS: Although further study is necessary, these results indicate that short wave diathermy may be an alternative treatment for patients with small spontaneous pneumothoraces.

Adolescent↗
PubMed1997

Rapid procedure for acid adaptation of oral lactic-acid bacteria and further characterization of the response.

Acid-adaptive responses could be induced readily in oral lactic-acid bacteria by growing them in batch cultures with excess sugar or more conveniently and rapidly by transferring cells to acidified growth media for the time required for biomass doubling. The response of Streptococcus mutans GS-5 was induced in a progressive rather than all-or-nothing way, and the extent of acid tolerance was inversely related to the pH of the inducing medium over a range from 8.5 to 5. The weak acids fluoride, acetate, or lactate did not measurably enhance acid adaptation, and so the response did not appear to depend primarily on changes in delta pH or the proton motive force across the cell membrane. Transcription and translation to form new proteins did appear to be necessary, as indicated by inhibition of adaptation by rifampin or chloramphenicol and by lack of adaptation by cells suspended in phosphate buffer at pH 5. Streptococcus salivarius and Lactobacillus casei were acid adapted by the rapid method, and the method appeared to be generally useful for oral lactic-acid bacteria. The rapid induction of the response in multiple oral lactic-acid bacteria suggests that it is of general importance for maintaining a diversity of organisms in the oral microbiota, which is regularly subjected to acid stresses.

Acetic Acid↗
PubMed1997

Physicians and smoking cessation. Development of survey measures.

Data from a mailed survey to primary care physicians (N = 122) were used to construct and evaluate psychosocial scales related to performance of smoking cessation counseling. Scales measuring counseling barriers, self-efficacy, and motivation demonstrated considerable promise with excellent or reasonable internal consistency. The correlation for each scale with performance of cessation counseling and with stage of change was statistically significant. Physicians who report they are currently assisting patients had higher performance and self-efficacy rating. Physicians who had participated in formal smoking cessation training had higher self-efficacy; however, their scores on the Barriers, Motivation, and Performance Scales did not differ. Further study with a representative group is encouraged.

Clinical Competence↗
PubMed1997

HER-2/neu gene amplification characterized by fluorescence in situ hybridization: poor prognosis in node-negative breast carcinomas.

PURPOSE: The HER-2/neu gene codes for a membrane receptor protein that is homologous, but distinct from the epidermal growth factor receptor. This investigation was performed to validate fluorescence in situ hybridization (FISH) as a sensitive and specific method for assessing HER-2/neu gene amplification in archival tissue and to test whether this alteration is associated with poor prognosis. MATERIALS AND METHODS: HER-2/neu gene amplification was determined by FISH in 140 archival breast cancers, previously characterized for gene amplification by Southern hybridization or dot-blot hybridization, and for gene expression by Northern hybridization, Western immunoblot, or immunohistochemistry. A separate cohort of 324 node-negative breast cancers was assessed for amplification by FISH to determine the utility of HER-2/neu gene amplification. RESULTS: Relative to solid-matrix blotting procedures, FISH analysis of HER-2/neu gene amplification showed a sensitivity of 98% and a specificity of 100% in 140 breast cancers. Among patients treated by surgery only, the relative risks (relative hazard) of early recurrence (recurrent disease within 24 months of diagnosis), recurrent disease (at any time), and disease-related death were statistically significantly associated with amplification. The prognostic information contributed by HER-2/neu amplification was independent of the other markers studied. CONCLUSION: FISH was an alternative technique for determining gene amplification and had some distinct advantages over Southern hybridization. Our results demonstrate that HER-2/neu gene amplification in the absence of adjuvant therapy is an independent predictor of poor clinical outcome and is a stronger discriminant than tumor size. Women with small tumors that had gene amplification were at increased risk of recurrence and disease-related death.

Aged↗
PubMed1997

[Construction of mycobacterium tuberculosis genomic library].

OBJECTIVE: To provide effective tools for identification and characterization of M. tuberculosis genes/antigenes and to evaluate their roles in diagnosis, vaccination, drug resistance, and pathogenesis. METHODS: M. tuberculosis genomic DNA obtained from H 37 Ra strain was partially digested with DNase I. The DNA fragments ranging from 4-8 kb were isolated from agarose gel and ligated to EcoR I adaptor, and the products were linked to lamda gt11 arms and packaged using an in vitro packaging extract. The different diluted bacteriophages were used to transfect bacteria Y1090. RESULTS: The efficiency and titer of the library were 85% and 3 x 10(5) pfu/ml, respectively. The library contained 1.3 x 10(5) individual recombinant phage whose foreign DNA inserted fragment size was 3.5 kb on average. CONCLUSION: The genomic DNA library constructed here can provide sufficient clone to cover H37Ra gene.

Genome, Bacterial↗
PubMed1997

[The characteristics of metal elements in airbone particle in Taiyuan].

Airbone particle samples were collected using a five-stage classification air sampler. The contents of 16 metals in different diameter airbone particles were determined by atomic absorption spectrophotometry. Variations in the contents of metals were observed in different seasons and areas. The results showed that the contents of most metals were higher in winter than in summer. The contents of metals were higher in urban districts than in suburbs. The metals of being harmful to human body mainly concentrated in the < or = 2.0 microns particles. The enrichment factor of metals was calculated. The results showed that Pb, Cu, Zn, As, Se and Sb mainly originated from man-made pollution, while Al, Fe and Ca mainly originated from natural sources.

Air Pollutants↗
PubMed1997

[Ocular socket plasty with orbital implant of hydroxyapatite].

OBJECTIVE: To evaluate the clinical effect of a new surgical procedure to reconstruct socket with sclera-encapsulated hydroxyapatite after enucleation and evisceration. METHODS: Hydroxyapatite spheres were implanted primarily into auto-sclera capsule in 41 cases. Secondary implantation was performed with heterosclera-encapsulated ones in 9 cases. RESULTS: No inflammation, implant extrusion and implant dislocation occurred in 7-23 months (mean = 15.6 months) of follow-up. CONCLUSION: Satisfactory prothetic motility was obtained in all cases.

Adolescent↗
PubMed1997

[Development of an expert system for assessment of criminal responsibility capacity of mentally ill offenders].

The objective of this study was to develop an expert system for the assessment of legal capacity (ESALC). Visual Basic for Windows 3.0 was employed in establishing ESALC, and 281 cases were assessed by the system. The results were in substantial agreement with those of expert assessment. Kappa = 0.68 (P < 0.01); accuracy 90.04%, sensitivity, 85.63% and specificity 96.49%. ESALC can be used as a supplementary instrument in forensic psychiatric assessment.

Adolescent↗