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Biomedical subjects

A Yang

Publications and source records attributed to A Yang.

At least 91 records · Page 5Linked to original sources
PubMed1995

Editing efficiency of hepatitis delta virus RNA is related to the course of infection in woodchucks.

Based on evidence in vitro which shows that the small form of hepatitis delta virus (HDV) antigen (S-HDAg) initiates virus replication, whereas the long form (L-HDAg) encoded by the edited L-genome inhibits replication, we first put forward the hypothesis that HDV RNA editing efficiency, i.e. the intracellular L/S-genome ratio, could be a determining factor on the course of the infection. In order to analyse the precise sequence of events after infection, woodchuck carriers of woodchuck hepatitis virus (WHV) were superinfected with HDV and sequential changes in HDV RNA editing efficiency were analysed in relation to the duration of viraemia. Our findings show that: (1) in both transiently and persistently viraemic woodchucks, the percentage of L-genome is higher at the early stage of onset of the disease than at the late stage; (2) at the early stage of onset the percentage of L-genome is higher in cases with transient viraemia than in those with persistent viraemia; (3) a relatively greater decrease in L-genome is seen later in transiently viraemic animals than in those that remain persistently viraemic. In view of the above findings in vivo and other supporting evidence in vitro, we propose a hypothesis for the pathogenesis of HDV. This hypothesis predicts the outcome of acute infection and we suggest a gene therapeutic approach for this disease based on the intracellular accumulation (or increase) of the L-genome.

Animals↗
PubMed1995

Radiography, sonography, and magnetic resonance imaging for stress incontinence. Contributions, uses, and limitations.

Imaging has increased our ability to understand stress incontinence and prolapse and has advanced our existing concepts of pathophysiology. Once these conceptual contributions have been made, imaging modalities may fade from current use, but the lessons learned will remain. It is the relationship of clinical imaging to conceptual development that is important. Conventional radiographic studies are well understood and can be obtained in most facilities. Sonographic units are currently available in many urologic and gynecologic clinics and offices and can be adapted for stress incontinence studies. The benefits of real-time studies and soft-tissue detail at the urethrovesical junction and office-based convenience make this an attractive new technique. The global pelvic approach offered by MR imaging offers spectacular imaging possibilities, which can help in complex cases and in future concepts in the field. MR imaging is rapidly evolving and may continue to offer new insights as technology permits. In accordance with Hodgkinson's earlier observations, imaging should not be routinely required in all patients undergoing evaluation for stress incontinence, but should certainly be considered in failed operations, complex prolapse, and when clinical diagnosis is in doubt. It is always better to use an imaging technique, no matter how expensive, than to end up with a bad surgical result.

Female↗
PubMed1995

[Effects of Sichuan herba Epimedii on the concentration of plasma middle molecular substances and sulfhydryl group of "yang-deficiency" model animal].

The effects of tonifying the kidney and strengthening the "Yang" produced by the extracts of Chinese herbs Epimedium wushanense and E. pubescens were studied in this paper. The results showed that both two herbs could decrease the concentration of plasma middle molecular substances and increase the concentration of plasma sulfhydryl group of "Yang-deficiency" model mice, thus suggesting that the above-said tonifying and strengthening effects of Herba Epimedii may result from its effects on middle molecular substances and sulfhydryl group, so as to strengthen the body resistance and eliminate the invading pathogenic factors.

Animals↗
PubMed1995

[The role of endoscopic ultrasonography and epidermal growth factor receptor assay in preoperative staging for gastric carcinoma].

Endoscopic ultrasonography (EUS) was performed in 36 patients with gastric carcinoma and the epidermal growth factor receptor (EGFR) of the specimen from endoscopic biopsy in 19 patients with gastric carcinoma was measured with immunoassay. Results of EUS were compared to the pathology of resected specimens according to the new (1987) TNM classification. EUS was very accurate in assessing the depth of tumor infiltration and the lymph node metastasis. Overall accuracy in T and N stage were 81% and 72% respectively. The level of EGFR in patients with infiltration into the neighbouring organs (97.7 +/- 27.9 fmol/mg pro.) were significantly higher than those without infiltration (47.7 +/- 21.3 fmol/mg pro.) (P < 0.01). The EGFR levels of those with lymph node metastasis (85 +/- 24.3 fmol/mg pro.) were significantly higher than that without lymph node metastasis (37.1 +/- 16.1 fmol/mg pro.) (P < 0.01). The results show that EUS as well as the EGFR assay could be used to determine the progress and prognosis of gastric carcinoma.

Adult↗
PubMed1995

[Adjustable reconditioner for the treatment of patella fracture].

Patella fracture belongs to the articular fracture. The operative methods to fix the patella fracture are numerous and there is no unanimous view. In order to protect the reconditioned patella, usually it is necessary to fix externally for a period of time. Since 1989, the authors have treated 165 cases of patella fracture with self designed, adjustable reconditioner and have acquired satisfactory results both in its fixing effect and function recovery. There was no need to fix the patella externally and the patients could do functional training in early stage. According to the assessment of the postoperative function and the motion limits of the knee and rehabilitation of the fracture, the results of the treatment were: excellent in 148 cases and good in 17 cases. This article describes the fixing mechanism of the reconditioner. It consists of the left and right petals and a screw. According to different sizes of patella and various types of the fracture, the reconditioner could be adjusted to connect the fracture closely with the petals and a screw. The structure of the reconditioner is simple, the operation is easy to carry out. It is adjustable during the operation and holds the fracture firmly and secure. It is suitable for all kinds of patella fracture avoiding partial or total resection of the patella. The other facture of the reconditioner is that the fixed patella could bear traction force when bending the knee at 90 degrees, so the patient could walk and squat on the heels normally.

Adult↗
PubMed1994

von Willebrand disease in the RIIIS/J mouse is caused by a defect outside of the von Willebrand factor gene.

An animal model for human type I von Willebrand disease (vWD) has been previously described in the inbred mouse strain RIIIS/J. Murine vWD is characterized by a prolonged bleeding time, normal von Willebrand factor (vWF) multimer distribution, autosomal dominant inheritance, and proportionately decreased plasma vWF antigen, ristocetin cofactor, and factor VIII (FVIII) activities. To study the molecular genetics of murine vWD, a portion of the vWF gene surrounding exon 28 was cloned, sequenced, and used to develop two informative DNA sequence polymorphisms for rapid genotyping by DNA polymerase chain reaction. RIIIS/J mice were crossed with PWK/Ph mice, an inbred line of Mus musculus musculus, and the F1 progeny backcrossed to the parental PWK/Ph strain. vWF antigen levels in F1 mice were not significantly different from the parental RIIIS/J strain but were markedly decreased compared with the parental PWK/Ph mice. Genetic linkage analysis of 104 backcross progeny showed no correlation between vWF antigen level and vWF genotype. These data indicate that murine vWD is caused by a defect at a novel genetic locus, distinct from the murine vWF gene. The distribution of vWF antigen levels among backcross progeny suggests the presence of one major dominant vWD gene in the RIIIS/J mouse with possible modifying contributions from one or more additional minor loci. These observations may provide new insights into the molecular basis and variable expressivity of human vWD.

Amino Acid Sequence↗
PubMed1994

At least four genes and sex are associated with susceptibility to urethane-induced pulmonary adenomas in mice.

Susceptibility to urethane-induced lung adenomas in mice has a polygenic mode of inheritance, with no obvious discontinuity in lung tumour counts among 37 AXB recombinant inbred strains. However, mean tumour counts were markedly higher in strains carrying the A/J allele at the Kras2 and H2 complex than in those carrying the C57BL/ allele. In 162 F2 hybrids and small numbers of both backcrosses between strain A/J (susceptible) and C57/BL/6 (resistant) mice, five factors influencing susceptibility were identified. Variation due to the 'major' Kras2 locus (chromosome 6) accounted for 60% of the total variation. 'Minor' loci linked to microsatellite markers Tnfb (in the H2 complex), D9Mit11 and D19Mit16 (on chromosomes 17, 9 and 19, respectively) accounted for a further 13% of the variation, and males had more tumours than females with sex differences accounting for 2% of the variation. No significant association with 32 other loci was detected. On a square-root transformed scale, heterozygotes at all marker loci were of intermediate susceptibility compared with homozygotes. The three minor loci and sex only affected lung tumour counts when at least one susceptible Kras2 allele was present.

Adenoma↗
PubMed1993

Prostate size and configuration in adults with bladder exstrophy.

A total of 13 men born with classical bladder exstrophy underwent magnetic resonance imaging examination of the pelvis to evaluate the size and configuration of the prostate and pelvic organs. Mean patient age was 25.2 years (range 19 to 38). Of the patients 4 are voiding per urethram and 9 have undergone urinary division. Measurements included prostate volume, weight and maximum axial cross sectional area; pubic diastasis, and seminal vesicle size. The mean prostatic cross sectional area was 10.1 +/- 3.4 cm.2. The mean estimated prostatic volume and weight were 20.7 +/- 8.2 cc and 21.7 +/- 8.6 gm., respectively. The mean seminal vesicle length and width were 2.1 +/- 0.99 and 1.1 +/- 0.38 cm., respectively. The volume, weight and maximum cross sectional area of the prostate appear normal compared to published norms. In none of the patients did the prostate extend circumferentially around the urethra and the urethra was anterior to the prostate in all patients. Also, the puborectalis muscle group was widely separated and only provided lateral support of the prostate in patients who were continent and who had undergone prior posterior iliac osteotomy. Thus, the attainment of continence in this complex group of patients is multifactorial and prostate growth as evaluated by magnetic resonance imaging may not influence continence in these patients.

Adult↗
PubMed1993

Lymphoma: monitoring tumor size and signal intensity with MR imaging.

To assess the potential value of magnetic resonance (MR) imaging in monitoring disease status, 34 patients with residual masses underwent MR imaging at sequential intervals. Patterns of signal intensity suggestive of active and inactive residual disease were compared to changes in tumor size. The signal intensity pattern was suggestive of persistent disease in 18 patients, even though tumor size was stable or decreased. Three of these patterns, seen within 6 months of initiation of therapy, were due to necrosis or inflammation. The MR imaging assessment of inactive disease was confirmed in 15 of the remaining 16 patients. In no case was an increase in tumor size seen in conjunction with a decrease in signal intensity. Because tumor size and signal intensity changes are not parallel in many cases, MR imaging may have a role in monitoring masses in patients with lymphoma. Signal intensity patterns, however, reflect gross histologic characteristics and cannot be considered specific, especially in the first 6 months after initiation of therapy.

Adolescent↗
PubMed1993

The in vitro destruction of rumen fluid carotenoids by plant lipoxygenases.

An ability to destroy carotenoids in the rumen of cattle may be an effective method of limiting their absorption from the small intestine which, in turn, is likely to result in reduced adipose tissue colour. Plant lipoxygenases are well known for their ability to bleach beta-carotene. As lutein is the major carotenoid present in most forage grasses, we have investigated the bleaching of lutein as well as beta-carotene by lipoxygenase isolated from soybeans. In vitro studies, using micellar preparations of carotenoids, indicated that lutein was rapidly oxidised and that the progress of the reaction was similar to that observed for beta-carotene. The polyunsaturated fatty acid linoleate was essential. When bovine rumen fluid was used as a source of carotenoid for in vitro studies with preparations of lipoxygenase, a rapid decrease in carotenoid and chlorophyll concentrations was observed, again requiring the addition of linoleic acid. The direct addition of soya flour to bovine rumen fluid resulted in the effective bleaching of the pigments without the inclusion of linoleate. When compared with flours from a variety of other plant sources, soya flour was most effective. The inclusion of dietary sources of lipoxygenase may be an effective method for controlling carotenoid uptake in certain ruminant species.

Animals↗
PubMed1993

A comparison of beta-carotene-splitting activity isolated from intestinal mucosa of pasture-grazed sheep, goats and cattle.

The in vitro enzymatic conversion of beta-carotene to retinal by partially purified preparations from the intestinal mucosa of sheep, goats and cattle was demonstrated. At pH 7.8 and 37 degrees C, this enzyme from sheep, goats and cattle displayed Michaelis-Menten type kinetics with a Vmax (nmol substrate split/mg protein/h) of 0.21, 0.27, and 0.04 and an apparent Km of 4.66 x 10(-6) M, 13.4 x 10(-6) M and 1.27 x 10(-6) M respectively. Maximal reaction was obtained by addition of an appropriate combination of detergent and bile salt, sodium dodecyl sulphate and egg lecithin. The cattle enzyme was inhibited by sodium glycocholate. The activity of sheep enzyme was higher (P < 0.05) than that of goats and cattle. The measured activity of the preparations from sheep, goats and cattle grazed on the same pasture reflected their contents of the reaction product, retinol, in the liver.

Animal Feed↗
PubMed1993

Nuclear medicine, contrast angiography, and magnetic resonance imaging for evaluating vascular problems in the hand.

Techniques for imaging the vascular tree have undergone change and development. Nuclear imaging can lead to decisions concerning diagnoses of masses, while contrast angiography with digital subtraction gives a complete picture of the vessels. Magnetic resonance angiography is the most exciting advance. Completely noninvasive, it yields much the same information as conventional contrast angiography.

Angiography↗