Biomedical subjects

Q Yang

Publications and source records attributed to Q Yang.

At least 253 records · Page 14Linked to original sources

PubMed1999

Role of membrane-type matrix metalloproteinase 1 (MT-1-MMP), MMP-2, and its inhibitor in nephrogenesis.

Extracellular matrix (ECM) proteins, their integrin receptors, and matrix metalloproteinases (MMPs), the ECM-degrading enzymes, are believed to be involved in various biological processes, including embryogenesis. In the present study, we investigated the role of membrane type MMP, MT-1-MMP, an activator pro-MMP-2, in metanephric development. Also, its relationship with MMP-2 and its inhibitor, TIMP-2, was studied. Since mRNAs of MT-1-MMP and MMP-2 are respectively expressed in the ureteric bud epithelia and mesenchyme, they are ideally suited for juxtacrine/paracrine interactions during renal development. Northern blot analyses revealed a single approximately 4.5-kb mRNA transcript of MT-1-MMP, and its expression was developmentally regulated. Inclusion of MT-1-MMP antisense oligodeoxynucleotide (ODN) in the culture media induced dysmorphogenetic changes in the embryonic metanephros. MMP-2 antisense ODN also induced similar changes, but they were relatively less; on the other hand TIMP-2 antisense ODN induced a mild increase in the size of explants. Concomitant exposure of MT-1-MMP and MMP-2 antisense ODNs induced profound alterations in the metanephroi. Treatment of TIMP-2 antisense ODN to metanephroi exposed to MT-1-MMP/MMP-2 antisense notably restored the morphology of the explants. Specificity of the MT-1-MMP antisense ODN was reflected in the selective decrease in its mRNA and protein expression. The MT-1-MMP antisense ODN also resulted in a failure in the activation of pro-MMP-2 to MMP-2. These findings suggest that the trimacromolecular complex of MT-1-MMP:MMP-2:TIMP-2 modulates the organogenesis of the metanephros, conceivably by mediating paracrine/juxtacrine epithelial:mesenchymal interactions.

Aging↗

PubMed1999

Pathophysiological topography of acute ischemia by combined diffusion-weighted and perfusion MRI.

BACKGROUND AND PURPOSE: Combined echoplanar MRI diffusion-weighted imaging (DWI), perfusion imaging (PI), and magnetic resonance angiography (MRA) can be used to visualize acute brain ischemia and predict lesion evolution and functional outcome. The appearance of a larger lesion by PI than by DWI quantitatively defines a mismatch of potential clinical importance. Qualitative lesion variations exist in the topographic concordance of this mismatch. We examined both the topographic heterogeneity and relative frequency of mismatched patterns in acute stroke using these MRI techniques. METHODS: Acute DWI, PI, and MRA studies of 34 prospectively recruited patients with supratentorial ischemic lesions scanned within 24 hours of stroke onset (range 2.5 to 23.3 hours, 12 patients <6 hours) were analyzed. RESULTS: Ischemic lesions were predominantly in the middle cerebral artery (MCA) territory (94%), with DWI lesions most commonly affecting the insular region. Mismatched patterns with PI lesion larger than DWI lesion occurred in 21 patients (62% overall), in all 4 patients imaged within 3 hours, and in 44% of patients imaged after 18 hours. A patient with a large PI but no DWI lesion and severe clinical deficit at 2.5 hours after stroke onset recovered completely. Regional variations in DWI and PI lesion loci were found, inferring site of proximal MCA occlusion, embolic pathogenesis, and regional arterial reperfusion. CONCLUSIONS: Analysis of the topographic concordance of PI and DWI lesions in acute stroke reveals regional PI lesions without concomitant DWI lesions, which do not necessarily progress to infarction but may suggest stroke pathogenesis and site of current arterial occlusion. Location of DWI lesions may suggest an earlier site of arterial occlusion and regions of maximal perfusion deficit.

Aged↗

PubMed1999

Identification of major ischemic change. Diffusion-weighted imaging versus computed tomography.

BACKGROUND AND PURPOSE: Thrombolytic therapy is not recommended in patients with CT changes of recent major infarction, which has been defined as reduced attenuation or cerebral edema involving >33% of the middle cerebral artery territory (European Cooperative Acute Stroke Study [ECASS] criteria). Diffusion-weighted imaging (DWI) is more sensitive than CT in detecting acute ischemia, and the combination of DWI, MR perfusion imaging, and MR angiography provides additional information from a single examination. We sought to determine whether DWI could identify the presence and extent of major ischemia as well as CT in hyperacute stroke patients. METHODS: Seventeen suspected hemispheric stroke patients were studied with both CT and DWI within 6 hours of symptom onset. None received thrombolytic therapy. The scans were examined separately by 2 neuroradiologists in a blinded fashion for ischemic change and cerebral edema, graded as normal, <33%, or >33% of the MCA territory. Final diagnosis of stroke was determined with the use of standard clinical criteria and T2-weighted imaging at day 90. RESULTS: Sixteen of 17 patients had a final diagnosis of stroke. Acute ischemic changes were seen in all 16 on DWI (100% sensitivity) and in 12 of 16 on CT (75% sensitivity). DWI identified all 6 patients with major ischemia on CT, with excellent agreement between the 2 imaging techniques (kappa=0.88). One patient eligible for thrombolysis on the ECASS CT criteria had major ischemia on DWI. CONCLUSIONS: DWI is more sensitive than CT in the identification of acute ischemia and can visualize major ischemia more easily than CT.

Adult↗

PubMed1999

Serial study of apparent diffusion coefficient and anisotropy in patients with acute stroke.

BACKGROUND AND PURPOSE: We sought to characterize the evolution of apparent diffusion coefficient (ADC) and apparent diffusion anisotropy (ADA) in acute stroke and to evaluate their roles in predicting stroke evolution and outcome. METHODS: We studied 26 stroke patients acutely (<24 hours), subacutely (3 to 5 days), and at outcome (3 months). Ratios of the ADC and ADA within a region of infarction and the normal contralateral region were evaluated and compared with the Canadian Neurological Scale, Barthel Index, and Rankin Scale. RESULTS: Heterogeneity in ADC and ADA evolution was observed not only between patients but also within individual lesions. Three patterns of ADA evolution were observed: (1) elevated ADA acutely and subacutely; (2) elevated ADA acutely and reduced ADA subacutely; and (3) reduced ADA acutely and subacutely. At outcome, reduced ADA with elevated ADC was observed generally. We identified 3 phases of diffusion abnormalities: (1) reduced ADC and elevated ADA; (2) reduced ADC and reduced ADA; and (3) elevated ADC and reduced ADA. The ADA ratios within 12 hours correlated with the acute Canadian Neurological Scale (r=0.46, P=0.06), subacute Canadian Neurological Scale (r=0.55, P=0.02), outcome Barthel Index (r=0.62, P=0.01), and Rankin Scale (r=-0.77, P<0.0005) scores. CONCLUSIONS: Combined ADC and ADA provide differential patterns of stroke evolution. Early ADA changes reflect cellular alterations in acute ischemia and may provide a potential marker to predict stroke outcome.

Acute Disease↗

PubMed1999

Effect of solvent composition during preparations on the characteristics of enoxacin microparticles.

We have studied the effect of the solvent system during preparation on the morphology, encapsulation efficiency, and release characteristics of enoxacin microparticles intended for localized delivery to the bone for the treatment of bone infections. Microparticles of enoxacin were formulated using poly(glycolic acid-co-DL-lactic acid) (PGLA) of different viscosity grades by the solvent-evaporation technique. Microparticles prepared with pure dichloromethane had smoother surfaces and less tendency to aggregate than microparticles prepared with dichloromethane-acetone solvent mixtures, which had porous surfaces. Approximately 65% of the microparticles prepared with pure dichloromethane were < 125 microm in diameter compared with 16% (approx.) of microparticles prepared with dichloromethane-acetone mixtures. Increasing the proportion of acetone from dichloromethane-acetone, 10:0, to dichloromethane-acetone, 1:1, resulted in an increase in encapsulation efficiency from 25 to 37%, and an increase in the yield of microparticles harvested from 39 to 51%. Although a further increase in the amount of acetone to dichloromethane-acetone, 1:9, had no significant effect on the yield, aggregation, or fraction of microparticles below 125 microm in diameter, the encapsulation efficiency increased to 56%. Approximately 55% of enoxacin was released in 24 h for microparticles prepared with dichloromethane-acetone, 1:9, compared with 100% release in 10h and 2h for microparticles of the same size range prepared with dichloromethane-acetone, 1:1, and dichloromethane-acetone, 10:0, respectively. The results suggest that the composition of the dichloromethane-acetone solvent system significantly influences the encapsulation efficiency and the rate of release of enoxacin from microparticles. This is important for the formulation of sustained-release enoxacin microparticles for the localized treatment of osteomyelitis.

Acetone↗

PubMed1999

Case-only design to measure gene-gene interaction.

The case-only design is an efficient and valid approach to screening for gene-environment interaction under the assumption of the independence between exposure and genotype in the population. In this paper, we show that the case-only design is also a valid and efficient approach to measuring gene-gene interaction under the assumption that the frequencies of genes are independent in the population. Just as the case-only design requires fewer cases than the case-control design to measure gene-environment interaction, it also requires fewer cases to measure gene-gene interactions.

Epidemiologic Studies↗

PubMed1999

[Detection of ABO genotypes by simultaneous PCR-RFLP method].

OBJECTIVE: To study human ABO genotyping by means of multiplex PCR and restriction fragment length polymorphism. METHODS: Two specific fragments of ABO gene were simultaneously amplified in a single tube, and then the double restriction digestion with RE Kpn I and Alu I was performed in the same tube. The amplified products were analyzed by PAGE and silver staining. A total of 125 Han unrelated individuals living in Wuhan were genotyped. RESULTS: Six genotypes of ABO were detected and the distribution was in good agreement with Hardy-Weinberg equilibrium. CONCLUSION: The results demonstrate that PCR-RFLP based approach is convenient, reliable and should be of value in forensic application.

ABO Blood-Group System↗

PubMed1999

Genome structure and evolution in the allohexaploid weed Avena fatua L. (Poaceae).

Allohexaploid wild oat, Avena fatua L. (Poaceae; 2n = 6x = 42), is one of the world's worst weeds, yet unlike some of the other Avena hexaploids, its genomic structure has been relatively little researched. Consequently, in situ hybridisation was carried out on one accession of A. fatua using an 18S-25S ribosomal DNA (rDNA) sequence and genomic DNA from A. strigosa (AA-genome diploid) and A. clauda (CC-genome diploid) as probes. Comparing these results with those for other hexaploids studied previously: (i) confirmed that the genomic composition of A. fatua was similar to the other hexaploid Avena taxa (i.e., AACCDD), (ii) identified major sites of rDNA on three pairs of A/D-genome chromosomes, in common with other Avena hexaploids, and (iii) revealed eight chromosome pairs carrying intergenomic translocations between the A/D- and C-genomes in the accession studied. Based on karyotype structure, the identity of some of these recombinant chromosomes was proposed, and this showed that some of these could be divided into two types, (i) those common to all hexaploid Avena species analysed (3 translocations) and (ii) one translocation in this A. fatua accession not previously observed in reports on other hexaploid Avena species. If this translocation is found to be unique to A. fatua, then this information, combined with more traditional morphological data, will add support to the view that A. fatua is genetically distinct from other hexaploid Avena species and thus should retain its full specific status.

Avena↗

PubMed1999

Synergistic anticancer effects of tetrandrine combined with doxorubicin or vincristine in vitro.

AIM: To study the interaction between tetrandrine (Tet) and doxorubicin (Dox) or vincristine (Vin) against human breast cancer cell lines MCF-7 and MCF-7/Dox or human nasopharyngeal cancer cell lines KB and KBV200 in vitro. METHODS: Anticancer activities of a drug alone and a drug combination of Tet and Dox or Vin were determined by tetrazolium (MTT) method. The interaction between Tet and Dox or Vin was evaluated by both a value of a sum of fractional inhibitory concentration (SFIC) and an isobologram method. RESULTS: The SFIC values of the three-different-ratio combinations between Tet and Dox ranged from 0.14 to 0.38 for MCF-7, and 0.10 to 0.29 for MCF-7/Dox; those of Tet-Vin combinations ranged from 0.21 to 0.37 for KB, and 0.32 to 0.63 for KBV200. All the SFIC values of the combination between Tet and Dox or Vin were less than 1.0 when the 3 ratios of the 2 drugs in combination were used, and the shapes of isobolic curves obtained from the combination were concave. CONCLUSION: The interaction between Tet and Dox or Vin against the human cancer cells was markedly synergistic.

Alkaloids↗

PubMed1999

Urinary symptoms and incontinence in women: relationships between occurrence, age, and perceived impact.

BACKGROUND: The prevalence of urinary symptoms that impact on quality-of-life will be important in determining resource allocation in primary care groups. AIM: To determine the prevalence of urinary symptoms and their perceived impact in a community population of women. METHOD: A postal survey using a validated self-completed questionnaire among all women aged over 18 years and registered with one general practice in a major British city. The prevalence rates and perceived impact of a wide range of urinary symptoms and their relationship with age was determined. Data were analysed using the chi-squared test and the chi-squared test for trend. Spearman's rank correlation was used to assess the relationship between symptom severity and perceived impact. RESULTS: The number of completed questionnaires returned was 2075, giving an 80% response rate. Of these, the number of women who reported some degree of incontinence in the previous month was 1414 (69%), although only 578 (30%) indicated that it had social or hygienic impact. Other lower urinary tract symptoms reported included nocturia (19%), poor stream (19%), urgency (61%), and dysuria (23%). The most troublesome symptoms were incontinence for no obvious reason, nocturnal incontinence, and nocturia, with 73%, 69%, and 63% of sufferers, respectively, finding these symptoms troublesome. CONCLUSIONS: Incontinence and other urinary symptoms are more common than previously thought. These symptoms are not always perceived as bothersome or as having a social or hygienic impact, and therefore many women who report urinary leakage do not require treatment. Nocturnal symptoms in women are commoner than might have been supposed and are extremely troublesome to sufferers.

Adult↗

PubMed1999

[Analysis and prevention of dislocation after total hip replacement].

OBJECTIVE: To analyse and prevent postoperative dislocation after total hip replacement (THR). METHODS: Of 850 cases operated on by THR 15 (1.7%) had postoperative dislocation. Eleven were revision cases while the other 4 were operated on their primary procedures. RESULTS: Postoperative dislocation after THR were found in 15 cases. Eleven cases had posterior dislocation by posterolateral approach after revision of THR. Anterior dislocation occurred in 2 cases who received lateral approach. Another two cases of dislocation were related to the design of prosthesis. Separation of polyethylene liner and metal shell in acetabular prosthesis was noted in the two cases. All the cases but 1 were reduced operatively. The cases with malpositioned prosthesis were revised operatively. Augmentation procedure was carried out to increase the strength of abductor. In one case, relocation of the great trochantor increased the strength of abductor. No redislocation was observed during follow-up. CONCLUSIONS: Postoperative dislocation after THR are due to malpositioning of prosthesis, unbalanced bilateral soft tissues, especially the loosening of abductor. Evaluating carefully the development of the pelvis and the deviation of normal bone markers is important in addition to accurate insertion and installment of the prosthesis intraoperatively. Complete clearance of osteophytes and bone cements around the acetabulumis reqaired apart from the repairment of adjacent soft tissues. Double check of hip stability should be carried out before the closure of incision.

Aged↗

PubMed1999

[Establishment of a stochastic model for variation in fecal Schistosoma japonicum egg count and estimation of its parameters].

OBJECTIVE: To establish a stochastic model suitable for interpreting the variation in fecal Schistosoma japonicum egg count, and to estimate its parameters and to describe it. METHODS: Total variation in fecal egg count with a stochastic model can be divided into two kinds of sources, (1) inter-individual variation, and (2) intra-individual variation. Parameters in the model were estimated with the data collected in actual fecal egg count. RESULTS: Parameters M and r differed and k kept nearly the same in various age groups. The best cut-off point of r and M for age-splitting was at eight and 12 years, respectively. Parameter k was assumed the same in different age groups in the model E, and r differed in the groups of 2 - 7 years and 8 years of age, and M differed in the groups of 2 - 11 years and 12 years of age, with a minimum value of Akaike information criterion (AIC). CONCLUSION: Age may be an important factor contributing to the estimations of parameters M and r, and the model E was the best one.

Adolescent↗

PubMed1999

[Light and electron microscope observations of heart and vascular tissues in animals acutely infected with tubercle bacilli].

The objective of this study was to observe the heart and vascular pathological lesions of some animals acutely infected with H37Rv tubercle bacilli. C57 BL/6N mice and rabbits were used for the establishment of the models. Light sections were stained with HE, Z-N, MCT and BCGS-P. Ultrathin sections were stained with uranyl and lead citrate and examined by electron microscope. The results showed that tubercle bacilli were present in heart and vascular tissues. Myocardial fibre, pericardium and vascular tissues had various degrees of lesions. The lesions of myocardial fibre and pericardium were more serious than that of the vascular tissues. These findings suggest that the toxin of the tubercle bacilli can damage the tissues of the infected animals, and the excessive reproduction can be also a factor detrimental to the infected tissues.

Acute Disease↗

PubMed1999

[Influence of pavulon on facial nerve monitoring during middle ear-mastoid operation].

OBJECTIVE: To evaluate the influence of pavulon (muscle relaxant) on facial nerve monitoring for patient with middle ear-mastoid operation during general anesthesia. METHOD: Intraoperative monitoring of the facial nerve (FNM) was done in 45 ears (44 case). For patient with middle ear-mastoid disease, 38 ears underwent inhaled-intravenous anesthesia with muscle relaxant pavulon (group of general anesthesia), 7 ears underwent local anesthesia (group of local anesthesia). Accelography (ACCG) was used in 10 case for testing the correlation between of FNM and the various degree of recovery from ulnar nerve-musculor blockade. RESULT: FNM could be elicited during different periods of recovery with values of T4/T1 varying from 10%-98%. Pavulon could be used to eliminate muscular vibration from disturbing FNM. Electromyography (EMG) potentials were successfully recorded in 34 ears (89.4%). Anesthesia was uneventful and it may be controled satisfactority. CONCLUSION: Considering the advantage of pavulon. It can be used for general anesthesia during intraoperative monitoring of the facial nerve for children or adults suffering from local complicated diseases.

Adolescent↗

PubMed1999

[The design of an ultrasonics Doppler spectrum analysis system for fetal umbilical blood flow monitoring].

This paper explains the design of an Ultrasonics Doppler Spectrum Analysis System for fetal umbilical blood flow monitoring. The gist of discussion includes the sampling method of the Doppler signals and the algorithm of the blood flow parameters. Because the DSP chip is not used in the AD cardboard, the hardware design is simplified and the system works steadily. In the process of computing the blood flow paramenters, an autochange method of the amplitude threshold and a timeout control technology are used, so the algorithm has good adaptability and works very stable.

Algorithms↗

PubMed1999

[The choice of the stapes surgical style in treatments of the otosclerosis].

OBJECTIVE: To investigate the effects of the stapes surgery on treatment of the otosclerosis to find out the more suitable surgical style. METHOD: 71 cases including 31 cases with stapes lifting surgery, 34 cases with partial stapcdectomy, 6 cases with total stapedectomy were summed. RESULT: Both the stapes lifting surgery and partial stapedectomy have steady effects on hearing level for a short or long time. CONCLUSION: The stapes lifting surgery should be adopted as the first surgical style for it is easier and the vestibular reaction is slighter. It will not affect the following surgical process even the two crura are broken.

Adult↗

PubMed1999

Evaluation of polycyclic aromatic hydrocarbon-DNA adducts in exfoliated oral cells by an immunohistochemical assay.

Polycyclic aromatic hydrocarbon-DNA adducts were evaluated in oral cells from 98 healthy volunteers by an immunohistochemical method using a specific antiserum against benzo(a)pyrene-DNA adducts revealed by the immunoperoxidase reaction. Mean adduct content, determined as relative staining intensity by absorbance image analyzer, was significantly higher in the cells from tobacco smokers compared with nonsmokers (330 +/- 98, n = 33 versus 286 +/- 83, n = 64, respectively) with a P = 0.013 obtained by two-sample t test with equal variances. We found that in the smoker group, the PAH-DNA adduct content increases with the number of cigarettes. Thus, the relative staining intensity was 305 +/- 105 in the group smoking 1-10 cigarettes/day (n = 16), 347 +/- 77 in the 11-20 group (n = 14), and 386 +/- 112 in the group smoking more than 20 cigarettes/day (n = 3; P = 0.03 by nonparametric test for trend). No significant association was detected between PAH-DNA adducts in oral cells and variables such as residential area, oral infections, alcohol or vitamin intake, grilled food consumption, and professional activity. This work confirms and extends previous data suggesting that this immunohistochemical method might be used as a valuable dosimeter of genotoxic damage in a carcinogen-exposed population, although further studies are needed to verify the applicability of the test in high-risk populations other than smokers.

Adolescent↗

PubMed1998

Hemochromatosis-associated mortality in the United States from 1979 to 1992: an analysis of Multiple-Cause Mortality Data.

BACKGROUND: Hemochromatosis, which can lead to serious chronic diseases resulting from iron overload, has an estimated prevalence of 50 to 80 cases per 10000 persons. However, little population-based information is available on the impact of hemochromatosis on morbidity and mortality. OBJECTIVE: To evaluate trends over 14 years in deaths and medical conditions associated with hemochromatosis in the United States. DESIGN: We searched Multiple-Cause Mortality Files compiled by the National Center for Health Statistics for the years 1979 to 1992 for all records listing hemochromatosis. We used these data to calculate age-adjusted and age-specific mortality rates, identify medical conditions associated with a known diagnosis of hemochromatosis at death, and calculate proportionate mortality ratios for these medical conditions. RESULTS: The listing of hemochromatosis on death certificates increased 60% from 1979 to 1992. Decedents with hemochromatosis were 23, 13, and 5 times more likely to have liver neoplasms, liver disease, and cardiomyopathy, respectively, than were decedents without hemochromatosis. Conversely, decedents with liver neoplasms, liver disease, and cardiomyopathy were 26, 14, and 5 times more likely, respectively, to have hemochromatosis than were decedents without these conditions. Hemochromatosis was 82 times more likely in persons with the combination of liver neoplasms and diabetes and 43 times more likely in those with the combination of liver disease and diabetes than in those without these conditions. CONCLUSIONS: Comparison of the reported prevalence of hemochromatosis among decedents with estimates of prevalence in the general U.S. population suggests that either the penetrance or the recognition of hemochromatosis, or both, is low. Nevertheless, substantial mortality resulting from liver disease, liver neoplasms, cardiomyopathy, and a combination of liver disease and diabetes in patients with hemochromatosis argues for the improved diagnosis and treatment of hemochromatosis in persons with these conditions.

Age Distribution↗