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Biomedical subjects

M L Yang

Publications and source records attributed to M L Yang.

At least 19 recordsLinked to original sources

Fibrinogen adsorption and platelet lysis characterization of fluorinated surface-modified polyetherurethanes.

A polyetherurethane (PU) was modified using fluorinated surface-modifying macromolecules (SMMs). A double radiolabel method was used simultaneously to measure the number of adhered platelets ((51)Cr) and the quantity of adsorbed Fg ((125)I), in a cone-and-plate instrument. The objectives were to determine if adsorbed Fg levels correlated to platelet adhesion on the surfaces, and to assess if any reductions in platelet adhesion for the SMM-treated surfaces resulted from surface-induced platelet lysis, rather than changes directly related to lower platelet activation and attachment on the novel surfaces. Platelet lysis was determined from lactate dehydrogenase (LDH) and unbound (51)Cr released into plasma isolated from whole blood exposed to test materials. The corresponding Fg adsorption, evaluated under the same platelet adhesion conditions, did not account for the reduced platelet adhesion on the treated surfaces. LDH and (51)Cr platelet release were very low and indicated no statistically significant differences between the materials. It was therefore concluded that platelet lysis did not contribute to the reduction in platelet adhesion characteristic observed on the SMM-treated surfaces. More importantly, the work emphasizes that the platelet activation cannot be inferred to by assessing the quantity of fibrinogen as is commonly done in the literature. The finding suggests a much more complex mechanism of action for the SMM surface modifiers. On-going work is investigating other Fg parameters such as protein binding affinity and protein conformational state in order to establish the mechanism by which the fluorinated surface modifiers may be reducing platelet adhesion via intermediary changes in initial protein adsorption.

Adsorption↗

Fibrinogen surface distribution correlates to platelet adhesion pattern on fluorinated surface-modified polyetherurethane.

In previous work, it had been shown that platelet adhesion could be reduced by fluorinating surfaces with oligomeric fluoropolymers, referred to as surface-modifying macromolecules (SMMs). In the current study, two in vitro blood-contacting experiments were carried out on a polyetherurethane modified with three different SMMs in order to determine if altered platelet adhesion levels could be related to the pattern of adsorbed protein and more specifically to the manner in which fibrinogen (Fg) distribution occurs at the surface. In the first experiment, the materials were placed in whole human blood and the adherent platelets were viewed with high-resolution scanning electron microscopy (SEM). In a second experiment, the materials were incubated with human plasma with the absence of platelets. The plasma contained 5% fluorescent-Fg. The materials were then viewed with a fluorescence microscope and images were collected to define the distribution of high-density fluorescent-Fg areas. The SEM and fluorescent-Fg images were imported to Image Pro Plus imaging software to measure the area, length and circularity and a bivariate correlation test was conducted between the two sets of data. For area and length morphology parameters, there were high and significant correlations (r > 0.9, p < 0.05) between the platelets and Fg aggregates. The data suggest that the Fg distribution may serve as a predictor of platelet morphology/activation and provides insight into the non-thrombogenic character of biomaterials containing the fluorinated SMMs.

Adsorption↗

Biological characterization of a novel biodegradable antimicrobial polymer synthesized with fluoroquinolones.

Biomaterial-related infections continue to represent a significant challenge to the medical community. Several approaches have been utilized to incorporate antimicrobial agents at the surface of implant devices in attempts to delay or eliminate the formation of biofilms. To date, most of these strategies have focused on drug conjugation or diffusion-limited systems for the delivery of such pharmaceutical agents. More recently, work has been presented on the feasibility of incorporating drugs into the backbone of polymers as a main-chain monomer. When sequenced into the backbone of the polymer with other monomers that are hydrolytically sensitive to enzyme-catalyzed breakdown, it is thought that drugs may be able to be selectively released. Specifically, degradable polyurethanes have been synthesized with fluoroquinolone antibiotics and have shown an ability to kill bacteria when released following degradation of the polymer chains by the macrophage-derived enzyme cholesterol esterase. However, specificity of the cleavage sites in the polymer was difficult to control. Since cholesterol esterase has specificity for hydrophobic moieties, it is desirable to alter the formulation of the polyurethanes to incorporate long hydrophobic monomers immediately adjacent to the ciprofloxacin molecule. Hence, the current study focuses on evaluating the enzyme-catalyzed degradation of a degradable polyurethane synthesized with 1,12 diisocyanatododecane as a substitute for 1,6 diisocyanatohexane, which was used in previous work. Validation of specific ciprofloxacin release and the generation of antimicrobial are shown. A preliminary cell study to assess the cytotoxicity of this biodegradable antibiotic polymer shows that the material has no observable effects on cell proliferation or cell membrane structure.

Animals↗

Humic acid induced growth retardation in a sertoli cell line, TM4.

Humic acid (HA) is a fluorescent deep brown organic, polymeric compound composed of phenolic acid. Intraperitoneal injection of HA in rats induced testicular morphological changes including degeneration of the seminiferous tubule, reduction in the number of Sertoli cells and spermatogonia, and a loss of spermatids. It was suggested that Sertoli cells may be involved in the progression of testicular atrophy. In this study, we used a mouse Sertoli cell Line, TM4, to investigate the effect of HA on Sertoli cells and the mechanism of the testicular atrophy induced by HA. We found that the cell growth of TM4 cells were reduced in 1 to 4 days of HA exposure. FACScan analysis of the DNA content of HA-treated TM4 cells revealed that there was no sub-G1 peak, indicating that the TM4 cells did not commit to the programmed cell death. However, a large proportion of TM4 cells were arrested at the G1 phase. The percentage of TM4 cells at the G1 phase increased from 36% to 84% after HA treatment for 4 days. Western blot assay of HA-treated TM4 cells showed that the expression of cyclin D1 protein decreased while the expression of p27kiP1 protein increased. These results suggest that HA-induced testicular atrophy is linked in part to an inhibitory effect on the growth of Sertoli cells. This model may be useful in investigation of environmental agents inducing testicular atrophy.

Animals↗

[Clinical observation on effect of xuejie jiawei decoction on vaginal hemorrhagic amount and duration in patients after drug-abortion].

OBJECTIVE: To observe the effect of Xuejie Jiawei Decoction (XJJWD) in reducing vaginal hemorrhagic amount, shortening hemorrhagic duration and lowering the curettage rate of incomplete abortion in patients after drug-abortion. METHODS: Group A was treated with XJJWD No. I from the 2nd day after abortion, one dose per day for 7 days. Group B was treated with XJJWD No. II from the 11th day after abortion, one dose per day for 5 days. The therapeutic effect of the two groups was compared with that of the untreated control group. RESULTS: In the Group A, the total score on vaginal hemorrhagic amount was markedly less than that in the control group (P < 0.01), and the vaginal hemorrhagic duration in patients with menostasis less than 45 days was shorter than that in the control group (P < 0.01). In the Group B, the total score on vaginal hemorrhagic amount in patients with menostasis less than 45 days was lower than that in the control group (P < 0.05). CONCLUSION: XJJWD could reduce the vaginal hemorrhagic amount and duration in patients after drug-abortion. It should be applied early after abortion, the less the duration of menostasis, the more effective the treatment.

Abortifacient Agents, Steroidal↗

Prenatal diagnosis and management of congenital cystic adenomatoid malformation.

Congenital cystic adenomatoid malformation (CCAM) is a rare pulmonary malformation resulting from excessive overgrowth of the terminal bronchioles. We present two CCAM case studies: type I (macrocystic) and type III (microcystic), diagnosed by antenatal ultrasonography at 31 and 21 weeks' gestation, respectively. In the former, multiple dilated cystic masses in the fetal left lung, with polyhydramnios, were identified during the antepartum examination. A postnatal thoracotomy with lobectomy was performed due to persistent cyanosis and resulted in a good outcome. In the latter case, an echogenic mass with multiple cysts in the fetal right lung was detected by prenatal sonography. The parents decided to terminate the pregnancy after prenatal counseling.

Adult↗

Brain-damaged survivors after intrauterine death of a monochorionic twin.

BACKGROUND: Potential risks for a surviving twin after fetal death of a co-twin in twin-to-twin transfusion syndrome (TTTS) has been documented. Although some studies suggest ending a twin pregnancy after a single fetal death as soon as possible in order to minimize the risks of thromboembolic complications in the surviving twin, we are more concerned about the risks of a premature birth. In this study, we searched for a potential marker to predict thromboembolic complications in the surviving twin. METHODS: From 1993 to 1998, nine women in two teaching hospitals had pregnancies complicated by TTTS and the death of one fetus. In addition to routine ultrasound examinations and obstetric monitoring, all patients had disseminated intravascular coagulation tests. The outcome of the surviving fetus was recorded. RESULTS: Three patients had silent and minimal coagulopathy (33%) that revealed only the presence of D-dimer. Among these three patients, two had a disappearance of serum D-dimer, but the other one had persistent D-dimer levels for more than 5 weeks and delivered a fetus with a cerebral infarction. Except for the above-mentioned fetus, all surviving fetuses were normal and healthy and were delivered at the median gestational age of 33 (range, 31-36) weeks. Of the nine surviving children, the mean interval between fetal death of one twin and delivery of the healthy twin was 22.7 days, ranging from 3 days to 47 days. CONCLUSIONS: All patients having TTTS associated with one fetal death should be carefully monitored for coagulopathy; the appropriate time for delivery might depend on the duration of persistent D-dimer in the maternal blood. The long-term presence of D-dimer in the maternal serum may indicate a severe underlying thromboembolic complication in the surviving twin after intrauterine death of a monochorionic twin. Due to the increased risks of morbidity in premature births, the benefit of early termination of pregnancy in order to protect against subsequent sequelae in the surviving twin is minor and remains an area for future research.

Adult↗

Review of pre-eclampsia in Taiwan: a multi-institutional study.

BACKGROUND: Because the reported frequency of pre-eclampsia in Taiwan varies significantly, the aims of this study were to measure the current incidence of pre-eclampsia and its correlated morbidity and mortality for both mothers and fetuses in Taiwan. METHODS: We retrospectively studied all reported cases of pre-eclampsia and eclampsia from January 1, 1993 to December 31, 1997 in the 14 tertiary medical centers and regional hospitals in Taiwan. Recruiting criteria were pregnancy-induced hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) with proteinuria (> or = 300 mg of urinary protein per 24 hours) and independent part edema. RESULTS: There were 4,193 patients with pre-eclampsia and eclampsia for a frequency of 2.03% of 206,551 deliveries during the study period. Of these, 58.9% of patients were classified as having mild pre-eclampsia while 38.4% had severe pre-eclampsia. Advanced maternal age (> 35 years) (odds ratio [OR] = 4.56; 95% confidence interval [CI] = 4.23-4.90; p < 0.001), primiparity (OR = 1.71; 95% CI = 1.61-1.82; p = 0.02) and twin pregnancy (OR = 1.92; 95% CI = 1.64-2.25; p = 0.01) were significant risk factors for developing pre-eclampsia. However, multivariate analysis showed that only advanced maternal age was a significant risk factor for pre-eclampsia (OR = 3.21; 95% CI = 2.95-3.50; p < 0.001). In contrast to mild pre-eclampsia, severe pre-eclampsia resulted in significantly worse outcomes for both mothers and fetuses. Complications in patients with severe pre-eclampsia included placental abruption, acute renal failure, pulmonary edema, postpartum hemorrhage, pleural effusion, preterm labor, intrauterine growth retardation, stillbirth, neonatal mortality and low birth weight infants, all of which occurred significantly more frequently than in patients with mild pre-eclampsia (p < 0.001). CONCLUSIONS: Pre-eclampsia remains a big challenge in modern obstetrics in Taiwan. Early diagnosis and management of patients with pre-eclampsia to prevent progression would significantly improve outcomes for mothers and fetuses.

Adult↗

[Mast cell in the gingival cancer: histochemical and electron microscopical study].

OBJECTIVE: To observe the relation between mast cells and gingival cancer. METHODS: The gingival cancer tissue of 24 cases and normal gingival tissue of 7 cases were studied with histochemical and electron microscopical methods. RESULTS: The results showed that the number of mast cells around the periphery of gingival cancer tissue increased significantly. The histochemical properties of these mast cells differed from the normal gingival tissue. The former did not contain heparin which was present normally. Under electron microscope, according to the characteristic ultrastructure, the mast cells around the gingival cancer were TC mast cells. Some of them showed the appearance of degranulation, and contacted intimately with cancer cells, lymphocytes and macrophages. CONCLUSION: These results suggested that together with lymphocytes, macrophages, the mast cell contributed to the defense reaction to the cancer tissue.

English Abstract↗

Role of the Janus kinase (JAK)/signal transducters and activators of transcription (STAT) cascade in advanced glycation end-product-induced cellular mitogenesis in NRK-49F cells.

Advanced glycation end product (AGE) is important in the pathogenesis of diabetic nephropathy, which is characterized by cellular hypertrophy/hyperplasia leading to renal fibrosis. However, the signal transduction pathways of AGE remain poorly understood. The Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway has been associated with cellular proliferation in some extra-renal cells. Because interstitial fibroblast proliferation might be important in renal fibrosis, we studied the role of the JAK/STAT pathway in NRK-49F (normal rat kidney fibroblast) cells cultured in AGE/BSA and non-glycated BSA. We showed that AGE dose-dependently (10-200 microgram/ml) increased cellular mitogenesis in NRK-49F cells at 5 and 7 days. However, cellular mitogenesis was unaffected by the simultaneous presence of BSA. Regarding the JAK/STAT pathway, AGE (100 microgram/ml) induced tyrosine phosphorylation of JAK2 (but not JAK1, JAK3 or TYK2) at 15-60 min; it also induced the tyrosine phosphorylation of STAT1 and STAT3 at 1-2 h and 0.5-4 h respectively. Being a transcription factor, AGE also increased the DNA-binding activities of STAT1 and STAT3 AG-490 (a specific JAK2 inhibitor) (5 microM) inhibited tyrosine phosphorylation of JAK2 and the DNA-binding activities of STAT1 and STAT3. The same results were obtained by using specific 'decoy' oligodeoxynucleotides (ODNs) that prevented STAT1 and STAT3 from binding to DNA. Meanwhile, the STAT1 or STAT3 decoy ODN and AG-490 were effective in reversing AGE-induced cellular mitogenesis. We concluded that the JAK2-STAT1/STAT3 signal transduction pathway is necessary for AGE-induced cellular mitogenesis in NRK-49F cells.

Animals↗

Peroxisome proliferation, adipocyte determination and differentiation of C3H10T1/2 fibroblast cells induced by humic acid: induction of PPAR in diverse cells.

Humic acid, a high-molecular-weight polyphenolic compound, exists abundantly in soil, natural water, and various terrestrial and aquatic environments. Humic acid causes peroxisome proliferation in mouse liver and induces the expression of peroxisome proliferator activated receptor (PPAR) in BNL CL.2 cells. Both cytotoxicity and flow cytometry show that humic acid inhibits the growth of C3H10T1/2 cells at G1 phase. C3H10T1/2 fibroblast cells express PPARgamma and the adipocyte P2 (aP2) genes which convert into adipocytes after being treated with humic acid. Our findings may provide a unique model for studying the molecular control of determination and differentiation of mesodermal cell lineages.

Adipocytes↗

Borderline ovarian tumors complicating pregnancy: a case report.

Although the majority of ovarian tumors complicating pregnancy are benign, they still pose a challenge because of the difficulty in differentiating between benign and malignant tumors during pregnancy. To our knowledge, the value of color Doppler ultrasound in the diagnosis of borderline malignant tumors complicating pregnancy remains unclear. We present the case of a 29-year-old pregnant woman with an ovarian tumor of low malignant potential. Preoperative ultrasound revealed a well-encapsulated cystic complex on the left ovary measuring 16 x 18 x 12 cm with an internally smooth surface, multiple septa ranging from 2 to 4 mm in thickness and a small solid component 2 cm in diameter, with a resistance index of 0.42. The differential diagnosis preoperatively was a borderline tumor. The patient underwent a left oophorectomy at 18 weeks of gestation. Frozen pathology indicated a mucinous cystadenocarcinoma of low malignant potential. A thorough surgical staging was completed. The final pathology confirmed mucinous cystadenocarcinoma of low malignant potential, stage IA. Postoperatively, the patient had an uneventful course and did not receive any adjuvant therapy. She delivered a normal male fetus weighing 3,450 g at 38 weeks of gestation. We conclude that color Doppler ultrasound is helpful for the preoperative diagnosis of borderline tumors of the ovaries but its usefulness for making an accurate diagnosis may require further evaluation.

Adult↗

Interaction between high glucose and TGF-beta in cell cycle protein regulations in MDCK cells.

Transforming growth factor-beta (TGF-beta) may mediate high glucose effects in renal cells. Thus, Madin-Darby canine kidney cells were studied for the modulation of cell cycle regulatory proteins by high glucose (27.5 mM) and TGF-beta1. We showed that unlike other renal cells, TGF-beta1 mRNA and its bioactivity were not induced by high-glucose culture. Furthermore, high glucose per se increased cellular proliferation without alterations in cell size. High glucose also increased the percentage of cells in the G2/M phase while decreasing cells in the G0/G1 phase of the cell cycle. In contrast, TGF-beta1 dose dependently (1 to 4 ng/ml) decreased cellular mitogenesis while increasing hypertrophy in the cells, especially in the presence of high glucose. TGF-beta1 also increased the percentage of cells arrested in the G0/G1 phase while decreasing cells in the G2/M phase of the cell cycle. Regarding two of the cell cycle regulatory proteins, high glucose increased cdc2 kinase activity and retinoblastoma protein (pRb) phosphorylation. In contrast, TGF-beta1 decreased cdc2 kinase activity and pRb phosphorylation, especially in the presence of high glucose. Additionally, glucose dose dependently (5.5, 16.5, 27.5, and 38.5 mM) increased type I and II TGF-beta receptor protein expression. In conclusion, changes in cdc2 kinase activity and pRb phosphorylation were correlated with high glucose and TGF-beta1-induced growth effects in a cell cycle-dependent manner in the Madin-Darby canine kidney cells. Furthermore, high glucose may potentiate TGF-beta1-induced effects by enhancing TGF-beta receptor protein expression.

Animals↗

Ovarian surgery during pregnancy and puerperium: twelve-year experience at the Veterans General Hospital-Taipei.

BACKGROUND: This study was performed in order to assess the surgical effects and characteristics of ovarian tumors during pregnancy and analyze their prognosis. METHODS: Between 1982 and 1993, 121 patients who had undergone ovarian surgery during pregnancy or puerperium were reviewed at the Veterans General Hospital-Taipei. These patients were analyzed with particular emphasis on the length of gestation at the time of surgery, complications related to the stage of pregnancy, surgical and pathologic findings and the outcome of pregnancy. RESULTS: Ovarian tumors were commonly detected during the second trimester (54.5%) and most of them (79.3%) were asymptomatic. The pathologic review found 38 patients (31.4%) with benign teratoma, 16 patients (13.1%) with corpus luteum and four patients (3.3%) with malignancy. There was a significant difference between emergent ovarian surgery and elective ovarian surgery in the spontaneous fetal wastage rate (14.1% vs 1%, p = 0.009). Compared with elective surgery, cases necessitating oophorectomy, with or without salpingectomy, increased significantly during emergency surgery (57% vs 36%, p = 0.03). All ovarian surgeries performed before a gestational age of seven weeks resulted in spontaneous fetal wastage. CONCLUSIONS: Although the majority of the ovarian tumors detected during pregnancy were benign, emergency laparotomy was sometimes required, which led to an increase in the risk of a fetal wastage. Preconception counseling should be emphasized because early removal of non-functional ovarian tumor before conception, especially teratoma, would decrease the incidence of ovarian surgery during pregnancy. Furthermore, elective and well-prepared surgical intervention appears to be a crucial factor for favorable pregnancy outcome.

Adult↗

Clinical manifestations in 105 persons with nevoid basal cell carcinoma syndrome.

Nevoid basal cell carcinoma syndrome (NBCC; Gorlin syndrome), an autosomal dominant disorder linked to 9q22.3-q31, and caused by mutations in PTC, the human homologue of the Drosophila patched gene, comprises multiple basal cell carcinomas, keratocysts of the jaw, palmar/plantar pits, spine and rib anomalies and calcification of the falx cerebri. We reviewed the findings on 105 affected individuals examined at the NIH since 1985. The data included 48 males and 57 females ranging in age from 4 months to 87 years. Eighty percent of whites (71/90) and 38% (5/13) of African-Americans had at least one basal cell carcinoma (BCC), with the first tumor occurring at a mean age of 23 (median 20) years and 21 (median 20) years, respectively. Excluding individuals exposed to radiation therapy, the number of BCCs ranged from 1 to > 1,000 (median 8) and 1 to 3 (median 2), respectively, in the 2 groups. Jaw cysts occurred in 78/105 (74%) with the first tumor occurring in 80% by the age of 20 years. The number of total jaw cysts ranged from 1 to 28 (median 3). Palmar pits and plantar pits were seen in 87%. Ovarian fibromas were diagnosed by ultrasound in 9/52 (17%) at a mean age of 30 years. Medulloblastoma occurred in 4 patients at a mean age of 2.3 years. Three patients had cleft lip or palate. Physical findings include "coarse face" in 54%, relative macrocephaly in 50%, hypertelorism in 42%, frontal bossing in 27%, pectus deformity in 13%, and Sprengel deformity in 11%. Important radiological signs included calcification of the falx cerebri in 65%, of the tentorium cerebelli in 20%, bridged sella in 68%, bifid ribs in 26%, hemivertebrae in 15%, fusion of the vertebral bodies in 10%, and flame shaped lucencies of the phalanges, metacarpal, and carpal bones of the hands in 30%. Several traits previously considered components of the syndrome (including short fourth metacarpal, scoliosis, cervical ribs and spina bifida occulta) were not found to be significantly increased in the affected individuals. This study delineates the frequency of the clinical and radiological anomalies in NBCC in a large population of US patients and discusses guidelines for diagnosis and management.

Adolescent↗

Rapid detection of trisomy 21 by homologous gene quantitative PCR (HGQ-PCR).

Down's syndrome results from the production of three copies of chromosome 21 within a cell. We have devised a method termed the homologous gene quantitative polymerase chain reaction (HGQ-PCR), which uses one pair of primers and which can directly identify the additional copy of chromosome 21 by simultaneously amplifying two highly homologous genes of the human liver-type phosphofructokinase located on chromosome 21 (PFKL-CH21) and the human muscle-type phosphofructokinase located on chromosome 1 (PFKM-CH1) for self-detecting determination. On analysis of 34 cases of Down's syndrome, including two cases of unbalanced translocation 46, XY, der (14; 21) (q10; q10), + 21, and 100 normal individuals, the relative ratio of the PFKM-CH1/PFKL-CH21 product was 1.33 +/- 0.323 (mean +/- SD) and 0.40 +/- 0.16 (mean +/- SD) for disomy DNA and trisomy DNA, respectively. The difference between these two groups was highly significant (P < 0.001). These results indicate that this quantitative method is practical and may be used for the prenatal diagnosis of Down's syndrome caused by trisomy 21.

Cells, Cultured↗

Clinical evaluation of urinary transforming growth factor-beta1 and serum alpha-fetoprotein as tumour markers of hepatocellular carcinoma.

To evaluate the diagnostic application of urinary transforming growth factor-beta1 (TGF-beta1) and serum alpha-fetoprotein (AFP) levels in hepatocellular carcinoma (HCC), TGF-beta1 and AFP were determined in 94 patients with cirrhotic HCC and in 94 sex- and age-matched patients with cirrhosis alone. TGF-beta1 and AFP levels in HCC were higher than in cirrhosis alone (P = 0.0001). There is an inverse correlation between TGF-beta1 and log AFP (r = -0.292, P = 0.004). Multivariate analysis indicated that TGF-beta1 and AFP were closely associated, in a dose-related fashion, with the development of HCC. Receiver-operating characteristic (ROC) curves were used to determine the optimal cut-off values of TGF-beta1 (50 microg g(-1) creatinine) and AFP (100 ng ml(-1)). Both TGF-beta1 and AFP showed a high specificity (99%) and positive likelihood ratio. The sensitivity was 53.1% for TGF-beta1 and 55.3% for AFP. The determination of both markers in parallel significantly increased the diagnostic accuracy (90.1%) and sensitivity (84%), with a high specificity (98%) and positive likelihood ratio (40.0). In conclusion, TGF-beta1 and AFP are independent tumour markers of HCC and may be used as complementary tumour markers to discriminate HCC from cirrhosis.

Adult↗