Biomedical subjects

C Yang

Publications and source records attributed to C Yang.

At least 235 records · Page 13Linked to original sources

PubMed1999

Spatial coherence of forward-scattered light in a turbid medium.

We study spatially coherent forward-scattered light propagating in a turbid medium of moderate optical depth (0-9 mean free paths). Coherent detection was achieved by using a tilted heterodyne geometry, which desensitizes coherent detection of the attenuated incident light. We show that the degree of spatial coherence is significantly higher for light scattered only once in comparison with that for multiply scattered light and that it approaches a small constant value for large numbers of scattering events.

Extraterrestrial Environment↗

PubMed1999

Breast tumor aromatase: functional role and transcriptional regulation.

Aromatase has been shown to be expressed at a higher level in human breast cancer tissue than in normal breast tissue, by means of enzyme activity measurement, immunocytochemistry, and RT-PCR analysis. Cell culture including MCF-7 breast cancer cells, animal experiments using aromatase-transfected breast cancer cells, and transgenic mouse studies have demonstrated that estrogen production in situ plays a more important role than circulating estrogens in breast tumor promotion. In addition, tumor aromatase is believed to be able to stimulate breast cancer growth through both autocrine and paracrine pathways, as demonstrated by a three-dimensional cell culture study. RT-PCR and gene transcriptional studies have revealed that the aromatase promoter is switched from a glucocorticoid-stimulated promoter, I.4, in normal tissue to cAMP-stimulated promoters, I.3 and II, in cancerous tissue. Recently, we identified and characterized a cAMP-responsive element (CREaro) upstream from promoter I.3 by DNA deletion and mutational analyses. Our results from promoter functional analysis also demonstrated an interaction between the CREaro and the silencer element (S1) that was identified previously in our laboratory. In the presence of cAMP, the positive regulatory CREaro can overcome the action of the silencer on the function of promoter I.3. On the basis of results generated from our own and other laboratories, we propose that, in normal breast adipose stromal cells and fibroblasts, aromatase expression is driven by promoter I.4 (glucocorticoid dependent), and that the action of promoters I.3 and II is suppressed by the silencer negative regulatory element. However, in cancer cells and surrounding adipose stromal cells, the cAMP level increases, and aromatase promoters are switched to cAMP-dependent promoters - I.3 and II. Furthermore, we applied the yeast one-hybrid screening method to search for proteins interacting with the silencer element, S1. The major protein identified was ERRalpha-1; however, SF-1, which is present in the ovary, is not detected in breast cancer tissue. Using a reporter plasmid with the aromatase genomic fragment containing promoter I.3 and S1, in breast cancer SK-BR-3 cells, ERRalpha-1 was found to have a positive regulatory function. It is believed that the silencer element in the human aromatase gene may function differently in different tissues, as a result of distinct expression patterns of transcription factors.

Animals↗

PubMed1999

Testing the efficacy of a recombinant merozoite surface protein (MSP-1(19) of Plasmodium vivax in Saimiri boliviensis monkeys.

Saimiri boliviensis monkeys were immunized with the yeast-expressed recombinant protein yP2P30Pv200(19). The antigen consisted of the C-terminus (amino acid Asn1622-Ser1729) of the merozoite surface protein 1 of the Plasmodium vivax Salvador I strain. Two universal T helper cell epitopes (P2 and P30) of tetanus toxin and six histidine residues for purification purposes were attached to the N- and C-termini, respectively. Four groups of five monkeys were given three immunizations at four-week intervals with either 250 microg of yP2P30Pv200(19) formulated with nonionic block copolymer P1005, 250 microg of antigen adsorbed to alum, 250 microg of antigen in phosphate-buffered saline (PBS), or PBS alone. Five weeks after the last immunization, each animal was inoculated with 100,000 parasitized erythrocytes of the Salvador I strain of P. vivax. Animals were splenectomized one week after challenge to increase parasite densities; after seven weeks of infection, animals were treated. Eighteen weeks later, the animals were rechallenged with the homologous parasite. Following the first challenge, three monkeys immunized with the antigen with P1005 were protected; no animals were protected from rechallenge. One monkey immunized with yP2P30Pv200(19) with alum was protected; no protection was seen after rechallenge. Two monkeys immunized with antigen alone were protected; none were protected from rechallenge. One control animal had a low parasite count following primary infection; none were protected against rechallenge. Adverse reactions were only observed with animals receiving P1005. It is proposed that splenectomy of the monkeys prevented adequate assessment of the efficacy of this antigen. Identification of a monkey host that supports high density parasitemia without splenectomy appears needed before further testing of blood-stage vaccines against P. vivax.

Adjuvants, Immunologic↗

PubMed1999

Role of eicosanoids in the pathogenesis of murine cerebral malaria.

Because microvascular damage is a common feature of cerebral malaria, we have examined the role eicosanoid metabolites (prostaglandins and leukotrienes) in experimental cerebral malaria. Eighty ICR mice were infected with Plasmodium berghei ANKA, with 40 uninfected mice as controls. Half of the infected mice were treated on days 4 and 5 with aspirin, a prostaglandin synthesis inhibitor. Infected mice started to die of cerebral malaria on day 6, and by day 17, all infected mice died. In contrast, all infected mice treated with aspirin died by day 12. Infected mice had increased phospholipase A2 mRNA expression in the spleen and cyclooxygenase 1 (COX1) and COX2 expression in the brain. At the peak of cerebral malaria, infected mice had higher serum leukotriene B4 levels than control mice, and aspirin-treated infected mice had higher serum leukotriene B4 levels than untreated infected mice. These results suggest that prostaglandins are protective whereas leukotrienes are detrimental in cerebral malaria.

Animals↗

PubMed1999

Cytokine production in rhesus monkeys infected with Plasmodium coatneyi.

Plasmodium coatneyi infection in rhesus monkeys has been used as a model for studying human malaria. Cytokine production in this model, however, has so far not been examined. In this study, four rhesus monkeys were infected with P. coatneyi, with another four animals serving as uninfected controls. Blood samples were taken for the determination of daily parasitemia, and cytokine and prostaglandin E2 (PGE2) levels at days 0, 3, 5, 7, and 10. All inoculated animals became infected, with synchronized appearance of ring-stage parasites. Infected monkeys had increased plasma levels of proinflammatory cytokines (interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha) during the late stage of the infection. They also had increased production of ciliary neurotrophic factor. In conjunction with the production of proinflammatory cytokines, infected monkeys also had gradual increases in the production of PGE2. A continued definition of the P. coatneyi/rhesus monkey animal model should be useful for the elucidation of the immunopathogenesis of human malaria.

Animals↗

PubMed1999

The physiological response of thrombopoietin (c-Mpl ligand) to thrombocytopenia in the rat.

It has been suggested that circulating levels of thrombopoietin (TPO) are determined primarily by platelet and megakaryocyte clearance of TPO and not by changes in hepatic TPO production. The experimental evidence accumulated so far to support this hypothesis is incomplete. We have therefore developed a new model of non-immune thrombocytopenia in the rat and used it to assess the relationship of TPO (c-mpl ligand) to the platelet mass. 14 d following the administration of busulphan, the platelet count reached a nadir of <2% of its initial value and remained at this level for up to 6 d. Circulating TPO was measured by two different bioassays which were sensitive enough to measure normal levels of TPO and levels rose from 106 +/- 29 pg/ml in animals with a normal platelet count to 2015 +/- 544 pg/ml in those with thrombocytopenia. These elevated levels of TPO were solely a response to the low platelet count since transfusion of a normal mass of platelets into the thrombocytopenic animals returned the TPO levels exactly to normal. The increase in TPO levels in thrombocytopenic animals was not due to increased TPO production since the thrombocytopenic animals did not show any increase in TPO mRNA in total or polysome-associated hepatic RNA. Rather, rat platelets were able to bind and stoichiometrically remove TPO from thrombocytopenic plasma via high-affinity receptors (Kd = 38 +/- 10 pm; 233 +/- 32 receptors/platelet). These results serve as a proof that the circulating level of TPO is determined not by alterations in TPO transcription or translation but by the ability of the platelet mass to bind and remove TPO from the circulation.

Animals↗

PubMed1999

Modifications to standard guidelines and changes in blood pressure readings: use of an automatic blood pressure device.

The purpose of the study was to determine what effect modifications to American Heart Association (AHA) guidelines produce when taking blood pressures with an automatic device. Eight blood pressure measurements were taken at least 2 minutes apart; two with standard AHA guidelines and six with modifications. Findings of this study suggest that elevation of the arm can have a significant effect on both the systolic and diastolic blood pressure. Two modifications, talking and placing the arm beside the trunk, raised the diastolic pressure. However, some modifications did not have a statistically significant effect. Techniques used to take blood pressures with an automatic device can have a significant effect on the readings.

Adult↗

PubMed1999

The expression of insulin-like growth factor II, hepatitis B virus X antigen and p21 in experimental hepatocarcinogenesis in tree shrews.

The purpose of this paper was to study the mechanism of synergistic effect in hepatocarcinogenesis induced by hepatitis B virus (HBV) infection and aflatoxin B1 (AFB1) intake. Immunohistochemical staining was used in formalin-fixed, paraffin-embedded sections of cancer and liver tissues. The incidence of hepatocellular carcinomas (HCCs) was 52.9% in experimental tree shrews that received both HBV and AFB1. It was significantly higher than that of animals exposed to HBV (11.1%, Group B), or (AFB1) (15.8%, group C) alone. HCC was not found in the control animals (group D). The expressions of insulin-like growth factor II (IGF-II) were 82.4%, 22.2%, 26.3% and 0 in groups A, B, C and D, respectively. The significant differences of IGF-II were observed between groups A and B, C and D (P < 0.05). The expressions of p21 were 29.4%, 11.1%, 15.8% and 0 in group A, B, C and D, respectively. The positive rate of hepatitis B x antigen (HbxAg) was significantly higher in the group A than that in the group B (52.9% vs. 11.1%, P < 0.05). The parallel relations between the incidence of HCC and the overexpressions of these genes protein have been found in each group. On the other hand, the expressions of these genes in tumour-bearing tree shrews were significantly higher than that in nontumour-bearing animals. These findings suggest a synergistic effects of HBV and AFB1 in activation of these genes in tree shrews. Overexpressions of these genes may take an important role in the course of hepatocarcinogenesis in tree shrews.

Aflatoxin B1↗

PubMed1999

Synergistic effect of hepatitis B virus and aflatoxin B1 in hepatocarcinogenesis in tree shrews.

An animal experiment with tree shrews was performed to detect the synergistic effects of hepatitis B virus (HBV) infection and dietary aflatoxin B1 (AFB1) in hepatocarcinogenesis. Adult healthy tree shrews (Tupaia belangeri chinensis) were divided into four groups: Group A (HBV + AFB1)--animals were infected with human HBV serum at first, then fed AFB1 diluted with milk, 150 ug/kg.bw/day, 6 days/week for 105 weeks. Group B (HBV)--animals were infected with human HBV as Group A, but no AFB1 treatment. Group C (AFB1)--animals were treated with AFB1 as Group A but no HBV infection. Group D--animals were treated neither with human HBV nor AFB1. During the experiment, blood samples and liver biopsies were taken regularly from all animals in each group. All the animals were sacrificed on the 160th week when the experiment ended. The samples of sera and liver tissues were checked for HBV markers and histological changes. Hepatocellular carcinomas (HCCs) were found only in Group A and Group C, with incidences of 67% and 30% respectively. The average time for HCC occurrence in Group A and Group C was 120.3 +/- 16.6 and 153.3 +/- 5.8 weeks respectively (P < 0.01). Even though no HCC occurred in Group B, 1 animal which died before the end of the experiment showed two large hepatocellular nodules. These results showed that there is synergistic effect between HBV and AFB1 in tree shrews' hepatocarcinogenesis, even though the hepatocarcinogenic effect played by HBV alone is rather weak.

Aflatoxin B1↗

PubMed1999

Observation of the efficacy of acupuncture and moxibustion in 62 cases of chronic colitis.

62 patients with chronic colitis were randomly divided into two groups. Acupuncture and moxibustion at acupoints such as Tianshu (St 25), Guanyuan (Ren 4) were applied in the treatment group, and western drugs were applied in the control group. The results showed that acupuncture and moxibustion had a marked curative effective with few side effects, and therefore was readily acceptable to the patients.

Acupuncture Therapy↗

PubMed1999

[Effects of MMP-1 expressing plasmid on rat liver fibrosis].

OBJECTIVE: To observe the effects of MMP-1(Matrix Metalloproteinase-1) expressing plasmid on rat liver fibrosis. METHODS: We constructed the rat's MMP-1 recombinant plasmid which can be expressed in eucaryotic cells. After encapsulating the MMP-1 recombinant plasmid by lipofectin, we transferred it to the rat's fibrotic liver in vivo intraperitoneally, then observed the effects of the plasmid on the fibrotic liver by RT-PCR, immunohistochemistry and the observation of pathology. RESULTS: The recombinant plasmid of MMP-1 could increase the degradation of type I and type III collagen in the rat's fibrotic liver according to immunohistochemistry compared with fibrotic modal group(P < 0.01) or compared with colchicine group(P < 0.05). According to the observation of pathology, recombinant plasmid of MMP-1 has some reverse effects on the rat's fibrotic liver compared with fibrotic model group(P < 0.05), but no obvious difference was found between the plasmid and colchicine(P > 0.05). CONCLUSION: The recombinant plasmid of MMP-1 has some reverse effects on liver fibrosis, but the effects is limited.

Animals↗

PubMed1999

Relationship between serum antisperm antibodies and anticardiolipin antibodies and clinical pregnancy outcome in an in vitro fertilization and embryo transfer program.

OBJECTIVE: To study the influence of maternal immunological factors on clinical pregnancy outcome in an in vitro fertilization and embryo transfer (IVF-ET) program. METHODS: One hundred and fifty IVF-ET treatment cycles from November 1995 to November 1996 were studied. The indication for IVF-ET treatment was bilateral blocked tubes. Serum antisperm antibodies and anticardiolipin antibodies were measured using enzyme-linked immunosorbent assay (ELISA). Cleavage rate and successful pregnancy rate in relation to antibody status of infertile women after IVF-ET treatment were assessed. RESULTS: Lower cleavage rate (64.2% +/- 32.1%) was found in 44 cycles of antisperm antibody seropositive women, compared with 84.8% +/- 18.7% in 106 cycles of seronegative women (P < 0.05). The clinical pregnancy rate was 31.8% in antisperm antibody-positive cycles and 20.8% in negative cycles (P > 0.05). The abortion rates of the two groups were similar (P > 0.05). Lower pregnancy rate (9.5%) was found in 21 cycles of serum anticardiolipin antibody-positive group, compared with 26.3% in 129 cycles of seronegative women (P < 0.05). Of patients with bio-chemical pregnancy and no pregnancy, 20.0% and 16.2%, respectively, had seropositive anticardiolipin antibody, compared with 5.6% of patients with clinical pregnancy (P < 0.05). CONCLUSION: Serum immunological factors may play a part in clinical pregnancy outcome in IVF-ET.

Adult↗

PubMed1999

Cloning and expression of beta 2-glycoprotein 1 recognized by antiphospholipid antibodies and its clinical investigation.

OBJECTIVE: To investigate cloning and expression of beta 2-glycoprotein 1 (beta 2GP1) recognized by antiphospholipid antibodies and to study the clinical significance of anti-beta 2GP1 antibodies in patients with autoimmune disease. METHODS: By using reverse transcription-PCR method, two kinds of expression plasmid which expressed beta 2GP1 and the fifth domain of beta 2-glycoprotein 1 (beta 2GP1-D5) proteins respectively were constructed in this study. Their antigenic activities were identified by immunoblots using rabbit anti-beta 2GP1 antibodies. Anti-r beta 2GP1 and anti-r beta 2GP1-D5 antibodies in the 112 patents were detected by ELISA using r beta 2GP1 and r beta 2GP1-D5 as coating antigens. RESULTS: A significant correlation in statistics (r = 0.667, P < 0.01) between the levels of anti-r beta 2GP1 and anticardiolipin antibodies (aCL) was found. The presence of anti-r beta 2GP1 antibodies was associated with an increased frequency of history of thrombosis and/or recurrent abortion. Anti-r beta 2GP1 assay provided better specificity than conventional aCL assay. The binding of anti-r beta 2GP1 from the sera of patients with antiphospholipid syndrome (APS) to r beta 2GP1 was inhibited by r beta 2GP1-D5. Meanwhile, of 28 patients who had positive anti-r beta 2GP1 antibodies in sera, 27 (96.4%) had positive anti-r beta 2GP1-D5 antibodies. CONCLUSION: It is indicated that antigenic epitope of beta 2 GP1 might be located in its fifth domain. Detection of anti-r beta 2GP1 antibodies may be of potential value for evaluating the risk of thrombosis and/or other APS associated symptom.

Antibodies, Antiphospholipid↗

PubMed1999

[Diagnosis and treatment of pulmonary hamartoma].

OBJECTIVE: To summarize the characteristics of pathogenesis, image, treatment and prognosis of pulmonary hamartoma. METHODS: 39 cases with hamartoma confirmed by pathology received surgical operation during 1971-1998 period. Their clinical data including symptoms, disease courses, image characteristics and surgery types were investigated. The prognostic results of 31 cases were collected by a follow-up study. RESULTS: The average age of morbidity was 44 years old and the mean disease course of hamartoma was 13 months. 21 cases without symptoms were determinated by chance and 18 cases with some extent of cough, expectoration, fever, chest distress, and short of breath. The hamartomas of 21 cases were in right lung, 18 in the left. Image characteristics presented as popcom-shaped tumor with clear border and without satellite focus. 31 cases underwent enucleation, 4 wedge-shaped resection, 3 lobectomy and 1 pneumonectomy. No recurrence or malignant change was demonstrated by follow-up study. CONCLUSIONS: Pulmonary hamartoma is a kind of neoplasms with satisfactory prognosis. Intraluminal hamartoma should be differentiated from hilar lung cancer. Localized resection should be performed for the treatment of the disease.

Adolescent↗

PubMed1999

[Long-term effectiveness of arthroscopic subsynovial sclerotherapy and suturing on recurrent dislocation of the temporomandibular joint].

OBJECTIVE: To evaluate long-term effect of arthroscopic surgery on recurrent mandibular dislocation. METHODS: 30 patients with 34 involved temporomandibular joints (TMJs) (26 unilateral, 4 bilateral) were treated by arthroscopic subsynovial sclerotherapy with or without a discal traction suture. Of them, four patients with 4 TMJs were undergone repeat arthroscopic operations. In total, 38 operations were performed in 34 TMJs. After arthroscopic lysis, lavage, and manipulation, the subsynovial sclerotherapy was performed with 5% sodium morrhuate and was located at retrodiscal lamina. Suturings were taken simultaneously in 19 cases, others (n = 19) were not sutured. The total amount of 5% sodium morrhuate was from 0.4 to 1.2 ml, and the numbers of injection points were from 2 to 5, and the subsynovial depth of injection was not more than 5 mm. The follow-up was from 1 mon to 8 years. RESULTS: The total success rate was 97% (33/34). There were 21 patients with 22 involved TMJs whose follow-ups were more than 2 years. The mean follow-up was 4 years (2-8 years). The long-term success rate was 95% (21/22). There were no serious complications. CONCLUSION: The long-term effectiveness of arthroscopic sclerotherapy and suturing on recurrent mandibular dislocation is stable.

Adult↗

PubMed1999

[Arthrocentesis and lavage of TMJ for the treatment of anterior disc displacement without reduction].

OBJECTIVE: To evaluate the clinical efficacy of the TMJ arthrocentesis and lavage as a treatment for anterior disc displacement without reduction of the TMJ. METHODS: 38 patients with limited mouth opening caused by anterior disc displacement without reduction were treated by using TMJ arthrocentesis and lavage. Clinical data including pain and mandibular motion were collected and then analyzed. Arthrography was used to evaluate disc position. RESULTS: The mandibular motion had increased significantly (P < 0.001) at different period of time, especially within 1 month. Jaw pain had also significantly improved (P < 0.01). Arthrography revealed that most of the TMJs studied had persistent anterior disc displacement with only 2 patients demonstrating a "reduced disc". CONCLUSION: Arthrocentesis and lavage is effective in reducing pain and increasing mandibular motion in patients with anterior disc displacement without reduction, especially in patients the duration of symptoms being less then 6 months. It is recommended as a simple alternative to more invasive TMJ procedures.

Adolescent↗

PubMed1999

[Adrenal cortical carcinoma].

OBJECTIVE: To study the diagnosis and treatment of adrenal cortical carcinoma. METHODS: Fifteen cases of adrenal cortical carcinoma (8 functional and 7 nonfunctional) were treated surgically during the period of 1978 - 1998. They were confirmed operatively and pathologically. RESULTS: The functional carcinoma usually showed typical clinical features such as Cushing's syndrome, primary aldosteronism, and adrenogenital syndrome. The nonfunctional had extra-adrenal symptoms such as acute abdominal pain and hypertension. A definite diagnosis can be made by the measurements of urine 17-ketosteroid, 17-hydrosteroid, cortisol, aldosterone, CT, and B-ultrasonography. CONCLUSIONS: Surgical removal of the tumor is the only effective treatment. Early diagnosis of adrenal cortical carcinoma is very difficult, especially in the non-functional.

Adolescent↗

PubMed1999

[Clinical and immunological studies on transplantation of total cornea with circular lamellar sclera].

OBJECTIVE: To observe the clinical results of total cornea with circular lamellar sclera transplantation (CST) and study its immunological mechanisms by animal experiments. METHODS: 109 patients with corneal transplantation were retrospectively analyzed, and according to the methods of operation they were divided into groups to compare their rate of rejection and the time of occurrence of corneal neovascularization. The methods of grouping and operation in animal experiments were similar to that in the clinical practice. RESULTS: The time of occurrence of neovascularization and rejection of CST were later than that in the total corneal transplantation (TCT), and the postoperative rate of rejection at 3 to 6 months was obviously increased in comparison with that in the partial penetrating keratoplasty (PKP). CONCLUSION: CST is an important method for rebuilding ocular anterior segment, and the donor limbus is active in the immunological of rejection.

Adult↗