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Biomedical subjects

A H Yang

Publications and source records attributed to A H Yang.

At least 37 records · Page 2Linked to original sources
PubMed1998

Tubular epithelial-myofibroblast transdifferentiation in progressive tubulointerstitial fibrosis in 5/6 nephrectomized rats.

BACKGROUND: Tubulointerstitial fibrosis is the final common pathway to end-stage renal failure. The present study investigated the potential role of tubular epithelial cells (TEC) in progressive fibrosis in the rat remnant kidney model. METHODS: Rats underwent 5/6 nephrectomy or a sham operation (control), and groups of six animals were killed at weeks 1, 3, 5, 9, 13, 17 and 21. RESULTS: Immunohistochemistry staining and in situ hybridization at week 3 after nephrectomy demonstrated de novo expression of alpha-smooth muscle actin (alpha-SMA)--a marker of smooth muscle cells and myofibroblasts--by TEC that was invariably associated with disruption of the tubular basement membrane (TBM). This phenotypic evidence of tubular epithelial-myofibroblast transdifferentiation was supported by ultrastructural studies identifying the presence of characteristic actin microfilaments and dense bodies within TEC with a transformed morphology. In the late stage of this apparent tubular epithelial-myofibroblast transdifferentiation, TEC lost apical-basal polarity and tight junctions, became elongated, detached from the TBM, separated from neighboring cells and appeared to migrate into the peritubular interstitium through the damaged basement membrane. Indeed, focal peritubular accumulation of alpha-SMA+ myofibroblasts and local tubulointerstitial fibrosis was closely associated with alpha-SMA+ tubules, suggesting a tubular epithelial origin for some of these cells. Quantitative analysis found a significant correlation between the number of alpha-SMA+ TEC and the accumulation of interstitial alpha-SMA+ myofibroblasts and the severity of tubulointerstitial fibrosis (both P < 0.001). CONCLUSIONS: This study provides phenotypic and morphological evidence to support the hypothesis that TEC are pro-fibrogenitor cells capable of tubular epithelial-myofibroblast transdifferentiation in progressive renal fibrosis. In addition, we postulate that disruption of the TBM, which facilitates epithelial cell contact with the interstitial matrix, promotes this process of transdifferentiation.

Actins↗
PubMed1998

Association of apolipoprotein E polymorphism with lipoprotein glomerulopathy. Report of 2 cases with a new genotype and comparison of the relative frequencies of apolipoprotein E isoforms in lipoprotein glomerulopathy and in the general population.

Two cases of lipoprotein glomerulopathy with a new apolipoprotein E (Apo E) genotype, epsilon3/epsilon4, were diagnosed recently. These 2 cases, together with other cases documented in English literature made a total of 6 common isoforms of Apo E encountered in lipoprotein glomerulopathy. Although the calculated allele frequency of epsilon2 is relatively high in cases with lipoprotein glomerulopathy as compared with that in the general population (39.3 vs. 6.4-11.4%), the gradual emergence of Apo E isoforms other than E2/E3 in lipoprotein glomerulopathy implicates that the genetic susceptibility of certain Apo E isoforms may not be a crucial factor. An alteration in the local environment of glomerular capillaries may be more important in the pathogenesis of lipoprotein glomerulopathy.

Adult↗
PubMed1998

High frequency of rearrangement of the RET protooncogene (RET/PTC) in Chinese papillary thyroid carcinomas.

The activation of RET protooncogene, through chromosomal translocation, is unique to papillary thyroid carcinomas. Rearrangement of the RET kinase domain to 3 partner genes has been described, of which the RET/PTC1 is the most common. To investigate the frequency of RET rearrangement in Chinese papillary thyroid carcinomas, we have performed RT-PCR to amplify specific RET/PTC transcripts. Among the papillary thyroid carcinomas of 11 patients examined, we have identified 2 containing RET/PTC1, 3 containing RET/PTC2, and 1 containing RET/PTC3 oncogenes. Although the cause of the high frequency of RET/PTC oncogenes in Chinese papillary thyroid carcinomas is unknown, our study suggests that RET rearrangement is an important genetic lesion underlying the development of thyroid papillary carcinoma in Taiwan.

Adult↗
PubMed1998

Absorbable PDS-II suture and nonabsorbable polypropylene suture in aortic anastomoses in growing piglets.

The long-term outcome of vascular anastomoses in children can be compromised by stenosis when the growth of the anastomosis does not match that of the vessels. This can be influenced by the suture material. We evaluated the suitability of the new generation of polydioxanone (PDS-II), an absorbable synthetic monofilament suture, in vascular surgery, in terms of permitting normal growth of aortic anastomoses. Ten piglets underwent primary end-to-end anastomosis of the thoracic aorta, five with PDS-II suture and five with conventional polypropylene (Prolene) suture. Six months after surgery, an aortogram was obtained for each animal. The piglets were then killed and the aortas were sent for pathologic examination. Complete absorption of suture material with slight dilatation of the anastomoses was found in all five pigs in the PDS-II suture group. We also found thrombus formation in one pig in this group. Mild stenosis of the anastomotic site was noted in all five pigs in the polypropylene suture group, but no intraluminal thrombus formation was seen. The degree of dilatation or stenosis within each group was not significantly different when intraluminal diameters were compared at three distinct sites in the reconstructed aorta (p > 0.05). The differences in vascular growth between the two groups were also not significant (p > 0.05). Histologic examination revealed less tissue reaction in the PDS-II suture group than in the polypropylene suture group. Thus, PDS-II seems to be a suitable suture material for anastomoses as far as vascular growth is concerned, but the possibility of aneurysm formation secondary to dilatation of the anastomotic site should be kept in mind.

Anastomosis, Surgical↗
PubMed1998

Focal segmental glomerulosclerosis after poststreptococcal glomerulonephritis in the elderly: a case report.

Acute poststreptococcal glomerulonephritis (PSGN) is quite rare in the elderly population. It is very difficult to recognize because the initial symptoms are similar to those of more common diseases of this age group. Compared with younger patients, elderly patients with PSGN tend to have a high incidence of renal function impairment and anuria or prolonged oliguria. Recovery from acute PSGN in the elderly is less predictable than in children and younger adults, especially when associated with severe impairment of renal function. We present the case of an elderly patient with PSGN, who had a skin infection of the face and anuria on admission. Percutaneous left renal biopsy was performed in the initial hospitalization period and in the recovery phase of the disease. Renal function recovered within two months. However, increased urinary white blood cell sediments with normal serum creatinine concentrations persisted in the successive three years of follow-up. Renal biopsy was repeated and showed evidence of focal segmental glomerulosclerosis.

Aged↗
PubMed1998

Metastatic leiomyosarcoma of the thyroid: a case report.

Metastatic malignant tumors of the thyroid are rarely encountered clinically. Most arise from primary sites in the lung, breast, kidney or gastrointestinal tract. Their clinical presentation may mimic a primary thyroid tumor and include signs and symptoms such as enlargement of the neck, hoarseness and dysphagia. Without a history of carcinoma in other organs, management as for primary thyroid tumor is often undertaken and misdiagnosis is common. This report concerns a 63-year-old female patient with a rapidly progressive enlargement of the neck. She had had a primary leiomyosarcoma lesion in her left leg that had been well controlled after wide excision. Bilateral pulmonary metastases were noted two years later without local recurrence. She receive wedge lung resections several times. To relieve progressive shortness of breath, debulking surgery of the thyroid was performed and metastatic leiomyosarcoma was proved. The related clinical data of this rare metastatic leiomyosarcoma of the thyroid is presented and the literature is reviewed.

Female↗
PubMed1998

Uterine myoma after cessation of gonadotropin-releasing hormone agonist: ultrasound and histopathologic findings.

BACKGROUND: This study attempted to search for the possible mechanism of regrowth of uterine myoma after cessation of gonadotropin-releasing hormone agonist (GnRHa) therapy. METHODS: Five premenopausal women presenting with symptomatic uterine myoma were prospectively studied in this trial. All patients were treated with a subcutaneous injection of goserelin depot 3.6 mg every four weeks for 16 weeks. Clinical examinations as well as hormonal and ultrasound determinations were performed before, during and after treatment to monitor the efficacy of therapy. At the end of the treatment period, all patients underwent myomectomy. The ultrastructural change of the myoma was evaluated postoperatively. RESULTS: The volume of the uterus decreased 21-57% and the volume of the uterine myoma decreased 21-65% after therapy. There was no significant change in resistance index of the uterine vessels or major vessels supplying the uterine myoma between pretreatment and post-treatment values. The morphologic features of the treated myoma showed marked cellular shrinkage and loss of myofibrillar structure. CONCLUSIONS: There is no significant cellular damage to the cellular structure that contributes to regrowth of treated intramural uterine myoma following cessation of treatment.

Antineoplastic Agents, Hormonal↗
PubMed1997

Peritoneal dialysis solution induces apoptosis of mesothelial cells.

For better simulation of the long-dwell exchanges in conventional CAPD, we have developed a modified mesothelial cell culture system consisting of a Transwell culture apparatus. The equilibration patterns of pH, dextrose and osmolality in the present culture system were observed to be very similar to those in human CAPD. The effects of six different peritoneal dialysis solutions on the apoptosis of mesothelial cells were evaluated using this modified culture system. The results imply that peritoneal dialysis solution per se may incite apoptosis of mesothelial cells, and also that low calcium peritoneal dialysis solution is a milder apoptosis stimulant as compared to the conventional peritoneal dialysis solution. Moreover, varying concentrations of dextrose in the peritoneal dialysis solution were not observed to significantly affect the apoptosis rate. The roles of ambient high concentrations of calcium and dextrose, low pH, as well as high osmolality in the apoptosis are also discussed.

Apoptosis↗
PubMed1997

Glomerular deposition of alpha 2-macroglobulin in glomerular diseases.

BACKGROUND: alpha 2-macroglobulin (alpha 2M) is a glycoprotein involved in delivery of growth factors, regulation of matrix degrading enzymes and modulation of fibrinolysis factors, all of which are considered as important pathogenic mechanisms of glomerular injury. However, the role of alpha 2M in glomerular disease has not been extensively studied. The amount, frequency and local distribution of alpha 2M in diseased glomeruli are similarly undetermined. METHODS: Two hundred and fifty renal biopsy cases with glomerular disease were collected. The glomerular deposition of alpha 2M was surveyed with immunofluorescence-microscopy and intraglomerular localization of alpha 2M was assessed by immunoelectron-microscopy. To clarify the relationship between circulatory concentration and local deposition of alpha 2M, serum samples were collected at time of biopsy and alpha 2M was determined using radial immunodiffusion assay. RESULTS: The amount and frequency of local deposition of alpha 2M in glomeruli varied from disease to disease, and the average positive rate was approximately 20%. Patients with minimal-change nephrotic syndrome and IgM nephropathy not only had the highest mean serum alpha 2M concentration but also exhibited higher frequency of glomerular deposition of alpha 2M (25.9 and 30% respectively). The local deposition of alpha 2M revealed by optical and electron-microscopy may not be directly related to the high serum level of alpha 2M. The deposited alpha 2M was observed to associate with electron-dense deposits, mesangial matrix and mesangial cells. CONCLUSIONS: To our knowledge, this is the first report that reveals the ultrastructural distribution of alpha 2M in glomerular disease. The relatively selective deposition of alpha 2M in some glomerular diseases strongly indicates that alpha 2M may play an active role in the modulation of local inflammatory reaction and tissue repair in these glomerular diseases.

Biopsy↗
PubMed1996

Dialyzer reuse: interaction between dialyzer membrane, disinfectant (formalin), and blood during dialyzer reprocessing.

The growing practice of dialyzer reuse in recent years is mainly based on medical and economic considerations. However, adverse reactions such as immunohemolytic anemia due to anti-Nform antibody associated with dialyzer reuse have been reported. In this study, scanning electron microscopy and cytologic staining were used to evaluate the interaction between blood components and the reprocessed synthetic dialyzer membrane (polysulfone) after disinfectant (formaldehyde) treatment. The results showed that various blood components such as fibrin and blood cells still adhered to the dialyzer membrane after reprocessing. The study also demonstrated that the adhered denatured blood components could be detached by sonication and/or simulated hemodialysis and then gain access into the circulation. The re-entry of the denatured blood components to the patients exposed to reused dialyzers may result in an enhanced immunological response which may contribute to antibody formation (such as anti-Nform antibody) with a reused hemodialyzer.

Anemia, Hemolytic↗
PubMed1996

Comparative radionuclide imaging of metastatic insular carcinoma of the thyroid: value of technetium-99m-(V)DMSA.

We report a case of metastatic insular carcinoma of the thyroid evaluated with 201TI, 99mTc-MIBI, 99mTc-(V)DMSA, 99mTc-MDP and 131I whole-body scans, which were obtained after total thyroidectomy. For the majority of lesions detected in the skeleton and soft tissue, 131I images were generally available, although most were visualized easier with 99mTc-(V)DMSA. Technetium-99m-MDP images were considered better than 99mTc-(V)DMSA images in showing bone lesions but not soft-tissue lesions. Both 201TI and 99mTc-MIBI scans provided sufficient advantage to exhibit neck and mediastinal metastases, but they did not surpass 99mTc-(V)DMSA in detecting abdominal or bony lesions. In this patient with various metastases from insular carcinoma of the thyroid, 99mTc-(V)DMSA seemed to be the tracer of choice for whole-body imaging.

Bone Neoplasms↗
PubMed1996

Giant cell fibroblastoma: a case report.

A one-year-old girl with a giant cell fibroblastoma (GCF) of the skin in the left arm is described. The tumor presented as a small, asymptomatic, subcutaneous mass that enlarged relatively slowly. GCF is a rare mesenchymal tumor occurring predominantly in young children. Its unique histopathological feature can lead to a misdiagnosis as sarcoma very easily. We review briefly the clinical and pathological information of 68 documented cases in the literature and discuss the pathogenesis of this peculiar neoplasm.

Dermatofibrosarcoma↗
PubMed1996

Poorly differentiated "insular" carcinoma of the thyroid: a case report.

Poorly differentiated "insular" carcinoma of the thyroid is a rare type of thyroid malignancy, situated morphologically and biologically in an intermediate position between well-differentiated (papillary and follicular) and undifferentiated (anaplastic) carcinoma. Here we report a case of a 56-year-old woman who developed a mass over the left thyroid gland in 1988, and received a thyroid operation in 1990 which was reported as benign lesion. Three years later, a mass recurred over the right lobe of the thyroid, and another thyroid operation was performed. The pathological report was medullary carcinoma. Four months later, recurrent mass over the right thyroid bed developed. Fine-needle aspiration biopsy of the mass showed moderately high cellularity with moderate pleomorphism, and multinucleated giant cells. Distinct cytoplasmic blue granules were also found in Liu's stain. She received total thyroidectomy and right neck radical dissection. Pathology examination showed well-defined nests of tumor cells ('insulae'), and immunohistochemical study showed positive stain for calcitonin. Pathologic diagnosis was poorly differentiated "insular" carcinoma of the thyroid. Four months after operation, recurrent neck mass over the suprasternal notch developed. Computerized tomography of neck and chest showed tumor mass over left thyroid bed with extension to anterior mediastinum. Whole body 131I scan showed mediastinum involvement and multiple bony metastases. Ablative 131I treatments (150 mCi and 200 mCi) were given twice, but in vain. The patient died 14 months after her last operation.

Carcinoma↗
PubMed1996

Langerhans' cell histiocytosis (histiocytosis-X) in a women with typical ultrastructure of Birbeck's granule: a case report.

A 28-year-old woman was admitted to our hospital with the chief complaint of progressive gingival swelling with easy bleeding and loosening of teeth for about two years. The liver and spleen were not enlarged and there were no lymphadenopathy. The hemogram was normal. The skull X-ray showed floating teeth. CT scan of face showed destructive bony lesions over maxilla and left mandible with adjacent soft tissue swelling. Pathologic examination of the gingiva revealed that the oral mucosal tissue was heavily infiltrated with histiocyte-like Langerhans' cells. The Langerhans' cells showed positive immunostain for S-100 protein. Under electron microscope, ultrastructure of the Langerhans' cells revealed typical intracytoplasmic tennnis racquet-shaped structure with a central zipper-like striation (Birbeck's granules). Langerhans' cell histiocytosis was diagnosed. She received rdiotherapy with a total dose of 1,000 cGy in fractions and oral chemotherapeutic drugs. Painful gingival swelling subsided gradually. She was followed at our OPD for the past 10 months and there was no evidence of local recurrence. Langerhans' cell histiocytosis is a rare disease. The relevant literature about its distinct pathologic features, clinical course and treatment is reviewed.

Adult↗
PubMed1995

Coexpression of a novel glomerular basement membrane matrix material in mesangial cell culture and glomerulosclerosis.

After in vivo administration of purified antibody against cultured mesangial cell (anti-MC IgG), glomerular basement membrane (GBM) was selectively bound. The glomerular bound anti-MC IgG exhibited a monospecificity for a 109-kDa antigen extracted from cultured mesangial cells and normal GBM. The antigen was not digestible by collagenase, heparitinase, or chondroitinase and was revealed by immunoelectron microscopy of a normal glomerular component to be predominantly distributed along the lamina rara externa of GBM and to be absent in mesangium. The ample expression of the antigen in puromycin aminonucleoside nephrosis implies that it represents a significant sclerotic material in glomerulonephritis. Abnormal production of GBM components by mesangial cells may play an important role in glomerulosclerosis.

Animals↗