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T T Sun

Publications and source records attributed to T T Sun.

At least 37 records · Page 2Linked to original sources
PubMed1999

Primary uroepithelial cultures. A model system to analyze umbrella cell barrier function.

Despite almost 25 years of effort, the development of a highly differentiated and functionally equivalent cell culture model of uroepithelial cells has eluded investigators. We have developed a primary cell culture model of rabbit uroepithelium that consists of an underlying cell layer that interacts with a collagen substratum, an intermediate cell layer, and an upper cell layer of large (25-100 micrometer) superficial cells. When examined at the ultrastructural level, the superficial cells formed junctional complexes and had an asymmetric unit membrane, a hallmark of terminal differentiation in bladder umbrella cells. These cultured "umbrella" cells expressed uroplakins and a 27-kDa uroepithelial specific antigen that assembled into detergent-resistant asymmetric unit membrane particles. The cultures had low diffusive permeabilities for water (2.8 x 10(-4) cm/s) and urea (3.0 x 10(-7) cm/s) and high transepithelial resistance (>8000 Omega cm2) was achieved when 1 mM CaCl2 was included in the culture medium. The cell cultures expressed an amiloride-sensitive sodium transport pathway and increases in apical membrane capacitance were observed when the cultures were osmotically stretched. The described primary rabbit cell culture model mimics many of the characteristics of uroepithelium found in vivo and should serve as a useful tool to explore normal uroepithelial function as well as dysfunction as a result of disease.

Animals↗
PubMed1999

Three-dimensional analysis of the 16 nm urothelial plaque particle: luminal surface exposure, preferential head-to-head interaction, and hinge formation.

The luminal surface of mouse urothelium in contact with the urine is almost entirely covered with plaques consisting of uroplakin-containing particles that form p6 hexagonal crystals with a center-to-center distance of 16 nm. A combination of quick-freeze/deep-etch images and our previous negative staining data indicate that the head domain of the uroplakin particle, which is exposed without an extensive glycocalyx shield, interacts closely with the head domains of the neighboring particles, while the membrane-embedded tail domains are farther apart; and that urothelial particles and plaques are not rigid structures as they can change their configuration in response to mechanical perturbations. Based on these data, we have constructed three-dimensional models depicting the structural organization of urothelial particles and plaques. Our models suggest that the head-to-head interaction may play a key role in determining the shape and size of the urothelial plaques. These models can explain many properties of urothelial plaques including their unique shape, detergent-insolubility, and morphological changes during vesicle maturation.

Animals↗
PubMed1999

New concepts of histological changes in experimental augmentation cystoplasty: insights into the development of neoplastic transformation at the enterovesical and gastrovesical anastomosis.

PURPOSE: To our knowledge the pathogenesis of malignancy associated with ileal cystoplasty, ureterosigmoidostomy and ileal conduits is currently unknown. To gain further insights into the mechanism of neoplastic transformation we studied histological changes in a canine augmentation cystoplasty model. MATERIALS AND METHODS: Enterocystoplasty and gastrocystoplasty were performed using a 5 to 7 cm. patch of ileum in 8 dogs and gastric antrum in 6. Specimens were harvested 4 months postoperatively. Representative 3 microm sections of the enterovesical and gastrovesical junctions were stained with hematoxylin and eosin. Uroplakin expression was assessed using an indirect peroxidase method subjected to double staining with alcian blue and periodic acid-Schiffreagent. RESULTS: The bladder portion of the augmentation cystoplasty had 3 to 4 stratified cell layers covered with a distinctive umbrella cell layer. Strong uroplakin staining was visible in all cell layers except the basal layer. At the enterovesical and gastrovesical junctions 6 to 10 layers of hyperplastic, urothelial appearing cells covered the glandular epithelium of the ileal and gastric segments. These cells expressed uroplakins. At this junction zone there was a marked decrease of underlying enteric glands, which had atrophied in proportion to the degree of urothelial hyperplasia. Double staining of uroplakin stained sections with alcian blue and periodic acid-Schiff reagent revealed mucosubstances in hyperplastic urothelial cells covering the enteral segments, indicating that the cells co-expressed uroplakins and mucins. CONCLUSIONS: Histological changes in this experimental canine model of augmentation cystoplasty indicated that the overgrowth of hyperplastic transitional epithelium develops at the enterovesical and gastrovesical junctions. These cells express not only uroplakins, but also mucosubstances. Our results suggest that the migrated hyperplastic urothelial cells have undergone changes characteristic of the enteric and gastric epithelium, which may have important implications in the pathogenesis of malignancy in bladder augmentations.

Anastomosis, Surgical↗
PubMed1999

Urothelial hinge as a highly specialized membrane: detergent-insolubility, urohingin association, and in vitro formation.

Urothelial surface is covered by numerous plaques (consisting of asymmetric unit membranes or AUM) that are interconnected by ordinary looking hinge membranes. We describe an improved method for purifying bovine urothelial plaques using 2% sarkosyl and 25 mM NaOH to remove contaminating membrane and peripheral proteins selectively. Highly purified plaques interconnected by intact hinge areas were obtained, indicating that the hinges are as detergent-insoluble as the plaques. These plaque/hinge preparations contained uroplakins, an as yet uncharacterized 18-kDa plaque-associated protein, plus an 85-kDa glycoprotein that is known to be hinge-associated in situ. Examination of the isolated, in vitro-resealed bovine AUM vesicles by quick-freeze deep-etch showed that each AUM particle consists of a 16-nm, luminally exposed "head" anchored to the lipid bilayer via a 9-mm transmembranous "tail", and that an AUM plaque can break forming several smaller plaques separated by newly formed particle-free, hinge-like areas. These data lend support to our recently proposed three-dimensional model of mouse urothelial plaques. In addition, our findings suggest that urothelial plaques are dynamic structures that can rearrange giving rise to new plaques with intervening hinges; that the entire urothelial apical surface (both plaque and hinge areas) is highly specialized; and that these two membrane domains may be equally important in fulfilling some of the urothelial functions.

Animals↗
PubMed1999

Detection of circulating uroplakin-positive cells in patients with transitional cell carcinoma of the bladder.

PURPOSE: Although transitional cell carcinoma of the bladder (TCC) metastasizes frequently with devastating consequences, no marker has been available to monitor this process. Uroplakins are a group of specific markers for normal urothelium and are continuously expressed by the majority of TCCs. Detection of uroplakin-positive cells in the circulation would be a strong indication of hematogenous dissemination of tumor cells in patients with TCC. MATERIALS AND METHODS: Total RNAs were extracted from peripheral blood of 60 patients with TCC (50 non-metastatic and 10 metastatic) and 10 healthy controls, reverse-transcribed and subjected to polymerase chain reaction amplification (RT-PCR) using oligonucleotide primers of human uroplakin II gene. A uroplakin-expressing human bladder cancer cell line (RT4) was used as a positive control to establish the sensitivity of the RT-PCR assay. RESULTS: We showed that the PCR-amplification of the mRNA encoding uroplakin II (UPII), a 15-kDa urothelium-specific marker, constitutes a highly sensitive and specific assay for detecting 100% of transitional cell carcinoma tissue, and that this assay can detect a single bladder cancer cell in a 5-ml. blood sample. UPII mRNA was detected in the blood samples of 2 patients with metastatic bladder cancer without chemotherapy and 1 out of 8 such patients with chemotherapy, but not in those of 50 non-metastatic patients or normal controls. CONCLUSIONS: Uroplakin II is a highly specific marker for human TCC and the detection of uroplakin II in the peripheral blood is associated with metastatic spread of bladder cancer cells. The specific and sensitive detection of uroplakin II provides a useful adjunct for detecting bladder cancer metastasis, staging, and monitoring chemotherapeutic response.

Biomarkers, Tumor↗
PubMed1999

Spiny keratoderma--a demonstration of hair keratin and hair type keratinization.

Six cases of spiny keratoderma were analyzed with hair specific antikeratin antibodies (AE13, AE14) and by electron microscopy. The keratotic column exhibited a different keratin birefringence and the underlying viable epidermis was less eosinophilic than the surrounding epidermis. AE13, which is specific for hair cortex, was positive in the lower column and variably positive in the viable epidermis, often beyond the columnar lesion. AE14 was negative in the lesion. Electron microscopy demonstrated features of keratinization of normal hair cortex, i.e. by the accretion of keratin filaments without production of keratohyalin or trichohyalin granules. Cementsomes (lamellar granules) and marginal bands were not produced as they are not formed in normal cortical keratinization. It was suggested that spiny keratoderma represents an ectopic hair formation of palms and soles.

Aged↗
PubMed1998

Uroplakin II gene is expressed in transitional cell carcinoma but not in bilharzial bladder squamous cell carcinoma: alternative pathways of bladder epithelial differentiation and tumor formation.

Uroplakins (UPs) are integral membrane proteins that are synthesized as the major differentiation products of mammalian urothelium. We have cloned the human UP-II gene and localized it on chromosome 11q23. A survey of 50 transitional cell carcinomas (TCCs) revealed a UP-II polymorphism but no tumor-specific mutations. Immunohistochemical staining using rabbit antisera against a synthetic peptide of UP-II and against total UPs showed UP reactivity in 39.5% (17 of 43 cases) of conventional TCCs, 12.8% (5 of 39) of bilharzial-related TCCs, and 2.7% (1 of 36) of bilharzial-related squamous cell carcinomas (SCCs). The finding that fewer bilharzial TCCs express UPs than conventional TCCs (12.8 versus 40%) raised the possibility that the former are heterogeneous, expressing SCC features to varying degrees. Our data strongly support the hypothesis that urothelium can undergo at least three pathways of differentiation: (a) urothelium-type pathway; (b) epidermis-type pathway; and (c) glandular-type pathway, characterized by the production of UPs, K1/K10 keratins, and secreted glycoproteins, respectively. Vitamin A deficiency and mesenchymal factors may play a role in determining the relative contributions of these pathways to urothelial differentiation as well as to the formation of TCC, SCC, and adenocarcinoma, or a mixture thereof.

Amino Acid Sequence↗
PubMed1998

Extracellular matrix changes in human corneas after radial keratotomy.

Extracellular matrix and basement membrane alterations were identified in human corneas after radial keratotomy. Ten normal and five radial keratotomy autopsy corneas (two at 6 months post surgery, and three at 3 years post surgery) were studied by immunofluorescence with antibodies to 28 extracellular matrix and basement membrane components. Outside of radial keratotomy scars, all studied components had a normal distribution. Of stromal extracellular matrix, only type III collagen accumulated around the scars. The basement membrane around epithelial plugs had a normal composition except for type IV collagen. Its alpha1-alpha2 chains, normally present only in the limbal basement membrane, appeared around all plugs. alpha3 and alpha4 chains were very weak or absent in these areas, contrary to nonscarred areas. This basement membrane pattern was similar to the normal limbal but not to the central corneal pattern. Keratin 3 also had a limbal-like, suprabasal expression in the plug epithelium. The stroma around the scars accumulated tenascin-C, fibrillin-1, types VIII and XIV collagen, all of which were absent from normal corneal basement membrane and extracellular matrix. Only tenascin-C showed less staining in anterior scars 3 years post surgery than 6 months post surgery, but still persisted in posterior scars. Incomplete scar healing was evident even 3 years post radial keratotomy. It was manifested by the accumulation of abnormal extracellular matrix in the anterior and posterior scars and by the limbal-like pattern of type IV collagen isoforms in the basement membrane around epithelial plugs.

Adult↗
PubMed1998

Autologous transplantation of urothelium into demucosalized gastrointestinal segments: evidence for epithelialization and differentiation of in vitro expanded and transplanted urothelial cells.

PURPOSE: Our study established a technique for in vitro expansion and subsequent transplantation of autologous urothelial cells into vascularized seromuscular segments from stomach and colon in sheep. The proof of proliferation and differentiation of the transplanted urothelium in the absence of resident urothelium is considered to be a prerequisite for use of this technique in bladder augmentation. MATERIALS AND METHODS: Autologous sheep urothelial cells were expanded in vitro and grown on collagen membranes for sheet grafting. Using a vital stain, viability and confluency status of the urothelial graft were determined before transplantation into demucosalized segments isolated from the sheep stomach and colon gastrointestinal pouches. The gastrointestinal segments were sewn up and remained in the abdomen as small pouches stiched to the abdominal wall. Take and differentiation of transplanted cells within the pouch were assessed two and three weeks later using histological and immunohistological means. RESULTS: Urothelial cells grew well on collagen membranes. A confluency status > 40% and co-culturing with 3T3 feeder cells favored successful transplantation. Two weeks after transplantation a multilayered urothelial-like epithelium was found to line the lumen of the pouch. The epithelium was characterized by a distinct urothelium-typical distribution of basal and luminal keratins and the expression of the umbrella cell-specific marker uroplakin III. Moreover, the epithelium had an underlying basal lamina which focally contained collagen type IV. CONCLUSIONS: The data indicate that in vitro expanded urothelial cells are capable of epithelializing demucosalized gastrointestinal segments forming a genuine, differentiated "neo" urothelium.

Animals↗
PubMed1998

The bladder as a bioreactor: urothelium production and secretion of growth hormone into urine.

Uroplakin genes are expressed in a bladder-specific and differentiation-dependent fashion. Using a 3.6-kb promoter of mouse uroplakin II gene, we have generated transgenic mice that express human growth hormone (hGH) in their bladder epithelium, resulting in its secretion into the urine at 100-500 ng/ml. The levels of urine hGH concentration remain constant for longer than 8 months. hGH is present as aggregates mostly in the uroplakin-delivering cytoplasmic vesicles that are targeted to fuse with the apical surface. Using the bladder as a bioreactor offers unique advantages, including the utility of all animals throughout their lives. Using urine, which contains little protein and lipid, as a starting material facilitates recombinant protein purification.

Animals↗
PubMed1998

Strategies of epithelial repair: modulation of stem cell and transit amplifying cell proliferation.

Using double labeling techniques, we studied the replication of corneal epithelial stem cells that reside exclusively in the limbal zone, and their progeny transit amplifying cells. We show that corneal epithelial stem cells can be induced to enter DNA synthesis by wounding and by TPA. We demonstrate the existence of a hierarchy of TA cells; those of peripheral cornea undergo at least two rounds of DNA synthesis before they become post-mitotic, whereas those of central cornea are capable of only one round of division. However, the cell cycle time of these TA cells can be shortened and the number of times these TA cells can replicate is increased in response to wounding. These results thus demonstrate three strategies of epithelial repair: (i) stem cell replication, (ii) the unleashing of additional rounds of cell proliferation that remain as an untapped reserve under normal circumstances, and (iii) enhancement of TA cell proliferation via a shortening of the cycling time.

Animals↗
PubMed1998

Phorbol ester preferentially stimulates mouse fornical conjunctival and limbal epithelial cells to proliferate in vivo.

PURPOSE: The authors investigated whether fornical epithelium displays a differential in vivo response to acute and chronic stimulation when compared with bulbar and palpebral epithelia. METHODS: To induce an increase in epithelial proliferation, 0.5% phorbol myristate (TPA) was topically applied in petrolatum daily to both eyes of SENCAR mice for 12 days. Control mice (three per group) received petrolatum only. After 6, 12, 18, and 24 hours (acute) and 2, 3, 4, 5, 7, 9, and 12 days (chronic) of TPA treatment, mice (three per group) were administered intraperitoneally 0.1 ml 40 microCi [3H]thymidine ([3H]TdR) 1 hour before they were killed. Conjunctival epithelium was fixed and processed for autoradiography, and the labeling index (LI; number of [3H]TdR-labeled nuclei per 1000 basal keratinocytes) was determined for each of the epithelial zones. RESULTS: Under normal situations, the LI was lowest in fornical epithelium (1.9 +/- 0.5) compared with bulbar (4.4 +/- 0.9) and palpebral (5.5 +/- 0.5) epithelia. Within 24 hours of TPA treatment, a 12-fold increase in fornical basal cell labeling was noted compared with a 2.5- and 5-fold increase in bulbar and palpebral basal cell labeling, respectively. Fornical epithelium maintained a significantly greater proliferative response (4.5-fold increase) during chronic stimulation than either bulbar or palpebral epithelia (0.5- and 1.5-fold increase, respectively). CONCLUSIONS: The more vigorous response of the fornical epithelium to acute and chronic stimulation is strong evidence that this epithelium has a greater proliferative capacity than the other two epithelia, which is consistent with the authors' hypothesis that conjunctival epithelial stem cells are primarily located in the fornical region.

Administration, Topical↗
PubMed1997

Uterine blood flow velocity waveforms during early postpartum course following caesarean section.

OBJECTIVE: To assess the change of uterine blood flow after Caesarean section. STUDY DESIGN: Doppler flow velocity waveforms were acquired from the uterine arteries and small arteries near the myometrial wound detected by transvaginal power Doppler ultrasonography in 23 patients on the 3rd, 6th and 9th postoperative days. RESULTS: The resistance index for the uterine artery did not show any change during the study period, while that for the small arteries slightly decreased. CONCLUSION: Uterine blood flow resistance after Caesarean section did not show any change during the early postpartum period.

Blood Flow Velocity↗
PubMed1997

Effects of serum from pregnant versus non-pregnant women on natural killer cell activity.

PROBLEM: To test the effect of serum obtained from in vitro fertilization-embryo transfer (IVF-ET) patients on the healthy volunteers natural killer (NK) cell activity. METHOD OF STUDY: Retrospective non-randomized clinical study. Suppressive effect on NK cell activity was measured with serum obtained from 25 pregnant and 24 non-pregnant women during IVF-ET procedure. RESULTS: Suppressive serum effect of volunteers' NK cell activity was significantly higher in pregnant than in non-pregnant women (P < 0.01). CONCLUSIONS: The suppressive activity of serum from pregnant women on NK cell suppression activity was useful in predicting the establishment of a successful pregnancy.

Adult↗
PubMed1997

Regulation of K3 keratin gene transcription by Sp1 and AP-2 in differentiating rabbit corneal epithelial cells.

Rabbit corneal epithelial cells cultured in the presence of 3T3 feeder cells undergo biochemical differentiation, as evidenced by their initial expression of K5 and K14 keratins characteristic of basal keratinocytes, followed by the subsequent expression of K3 and K12 keratin markers of corneal epithelial differentiation. Previous data established that mutations of an Sp1 site in a DNA element, E, that contains overlapping Sp1 and AP-2 motifs reduce K3 gene promoter activity by 70% in transfection assays. We show here that Sp1 activates while AP-2 represses the K3 promoter. Although undifferentiated corneal epithelial basal cells express equal amounts of Sp1 and AP-2 DNA-binding activities, the differentiated cells down-regulate their Sp1 activity slightly but their AP-2 activity drastically, thus resulting in a six- to sevenfold increase in the Sp1/AP-2 ratio. This change coincides with the activation and suppression of the differentiation-related K3 gene and the basal cell-related K14 keratin gene, respectively. In addition, we show that polyamines, which are present in a high concentration in proliferating basal keratinocytes, can inhibit the binding of Sp1 to its cognate binding motif but not that of AP-2. These results suggest that the relatively low Sp1/AP-2 ratio as well as the polyamine-mediated inhibition of Sp1 binding to the E motif may account, in part, for the suppression of the K3 gene in corneal epithelial basal cells, while the elevated Sp1/AP-2 ratio may be involved in activating the K3 gene in differentiated corneal epithelial cells. Coupled with the previous demonstration that AP-2 activates the K14 gene in basal cells, the switch of the Sp1/AP-2 ratio during corneal epithelial differentiation may play a role in the reciprocal expression of the K3 and K14 genes in the basal and suprabasal cell layers.

3T3 Cells↗
PubMed1997

Clonal analysis of the in vivo differentiation potential of keratinocytes.

PURPOSE: This study investigated the in vivo differentiation of conjunctival keratinocytes. METHODS: Keratinocytes from the fornical region of the conjunctival epithelium were isolated and plated at low density (5 x 102 per 100-mm dish) in Dulbecco's minimum essential medium containing 20% fetal bovine serum in the presence of mitomycin C-treated 3T3 feeder cells. At this density, only single, isolated cells were attached after overnight culture. Eight days later, small, well-isolated colonies separated from one another by the feeder cells were detached as a sheet from the dish and were injected subcutaneously into the flanks of BALB/c athymic mice through an 18-gauge needle. Within a day, a small firm nodule appeared at the site of injection. At different time points, the animals were killed, and the nodules were excised for morphologic, histogeometric, and cell kinetic analyses. RESULTS: Each implanted colony derived from a single cell gave rise to a single epithelial cyst lined with a reconstituted stratified epithelium. Goblet-like cells loaded with periodic acid-Schiff-positive cytoplasmic granules began to appear singularly in some of the cysts by day 8 postimplantation and were observed in approximately 85% of the cysts by day 14. CONCLUSIONS: Because the cysts formed were derived from clonal populations of epithelial cells and the majority of cysts had a mixed keratinocyte-goblet cell phenotype, these results suggest strongly the existence of a bipotent precursor cell in conjunctival epithelium that can give rise to both goblet and nongoblet cells. This system can be used to study factors that can influence the commitment of pluripotent epithelial stem cells to divergent pathways of differentiation.

Animals↗
PubMed1996

In vitro binding of type 1-fimbriated Escherichia coli to uroplakins Ia and Ib: relation to urinary tract infections.

Urinary tract infections, caused mainly by Escherichia coli, are among the most common infectious diseases. Most isolates of the uropathogenic E.coli can express type 1 and P fimbriae containing adhesins that recognize cell receptors. While P fimbriae recognize kidney glycolipid receptors and are involved in peyelonephritis, the urothelial for type 1 fimbriae were not identified. We show that type 1-fimbriated E. coli recognize uroplakins Ia and Ib, two major glycoproteins of urothelial apical plaques. Anchorage of E. coli to urothelial surface via type 1 fimbriae-uroplakin I interactions may play a role in its bladder colonization and eventual ascent through the ureters, against urine flow, to invade the kidneys.

Adhesins, Bacterial↗