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Biomedical subjects

C C Yao

Publications and source records attributed to C C Yao.

18 recordsLinked to original sources
PubMed2001

Trophoblast-specific expression and function of the integrin alpha 7 subunit in the peri-implantation mouse embryo.

For implantation and placentation to occur, mouse embryo trophoblast cells must penetrate the uterine stroma to make contact with maternal blood vessels. A major component of the uterine epithelial basement membrane and underlying stromal matrix with which they interact is the extracellular matrix protein laminin. We have identified integrin alpha 7 beta 1 as a major receptor for trophoblast-laminin interactions during implantation and yolk sac placenta formation. It is first expressed by trophectoderm cells of the late blastocyst and by all trophectoderm descendants in the early postimplantation embryo through E8.5, then disappears except in cells at the interface between the allantois and the ectoplacental plate. Integrin alpha 7 expression is a general characteristic of the early differentiation stages of rodent trophoblast, given that two different cultured trophoblast cell lines also express this integrin. Trophoblast cells interact with at least three different laminin isoforms (laminins 1, 2/4, and 10/11) in the blastocyst and in the uterus at the time of implantation. Outgrowth assays using function-blocking antibodies show that alpha 7 beta 1 is the major trophoblast receptor for laminin 1 and a functional receptor for laminins 2/4 and 10/11. When trophoblast cells are cultured on substrates of these three laminins, they attach and spread on all three, but show decreased proliferation on laminin 1. These results show that the alpha 7 beta 1 integrin is expressed by trophoblast cells and acts as receptor for several isoforms of laminin during implantation. These interactions are not only important for trophoblast adhesion and spreading but may also play a role in regulating trophectoderm proliferation and differentiation.

Alternative Splicing↗
PubMed2001

Purification of mouse primary myoblasts based on alpha 7 integrin expression.

Fundamental insights have come from the study of myogenesis. Primary myoblasts isolated directly from muscle tissue more closely approximate myogenesis than established cell lines. However, contamination of primary muscle cultures with nonmyogenic cells can complicate the results. To overcome this problem, we previously described a method for myoblast purification based on novel culture conditions (T. A. Rando and H. M. Blau, 1994, J. Cell Biol. 125, 1275--1287). Here we report a refinement of this method that leads directly to an enriched population of mouse primary myoblasts, within significantly fewer population doublings. The method described here avoids using adhesion as a criterion for selection. This advance capitalizes on the ability of the antibody CA5.5 to recognize alpha 7 integrin, a muscle-specific cell surface antigen. Enrichment of myoblasts to greater than 95% of the cell population can be achieved by a single round of flow cytometry or magnetic bead separation. This is the first description of a mouse myoblast purification method based on a cell-type-specific antigen. The ease of this procedure for isolating primary myoblasts should expand the opportunities for (1) using these cells in cell transplantation studies in animal models of human disease, (2) isolating and characterizing mutant myoblasts from transgenic animals, and (3) allowing in vitro studies of molecules that regulate muscle cell growth, differentiation, and neoplasia.

Animals↗
PubMed2001

Integrin alpha3beta1 engagement disrupts intercellular adhesion.

During tissue morphogenesis and tumor invasion, epithelial cells must undergo intercellular rearrangement in which cells are repositioned with respect to one another and the surrounding mesenchymal extracellular matrix. Using three-dimensional aggregates of squamous epithelial cells, we show that such intercellular rearrangements can be triggered by activation of beta1 integrins after their ligation with extracellular matrices. On nonadherent substrates, multicellular aggregates (MCAs) formed rapidly via E-cadherin junctional complexes and over time became compacted spheroids exhibiting a more epithelial phenotype. After MCAs were replated on culture substrates, the spheroids collapsed to yield tightly arranged cell monolayers. Cell-cell contact induced rapid elevation in E-cadherin levels, which was due to an increase in the metabolic stability of junctional receptors. During MCA remodeling of cell-cell adhesions, and monolayer formation, their E-cadherin levels fell rapidly. Similar behavior was obtained regardless of which ECM ligand-collagen type I, fibronectin, or laminin 1-MCAs were seeded on. In contrast, when seeded onto a matrix elaborated by squamous epithelial cells, cells in the MCA attached, spread, lost cell-cell junctions, and dispersed. Analysis identified laminin 5 as the active ECM ligand in this matrix, and MCA dispersion required functional beta1 integrin and specifically alpha3beta1. Furthermore, substrate-immobilized anti-integrin antibody effectively reproduced the epithelial-mesenchymal-like transition induced by the laminin 5 matrix. During the early stages of aggregate rearrangement and collapse, cells on laminin 5 substrates, but not those on collagen I substrates, exhibited intense cortical arrays of F-actin, microspikes, and fascin accumulation at their peripheral surfaces. These results suggest that engagement of specific integrin-ligand pairs regulates cadherin junctional adhesions during events common to epithelial morphogenesis and tumor invasion.

Antibodies, Monoclonal↗
PubMed2001

Transfection of MCF-7 carcinoma cells with human integrin alpha7 cDNA promotes adhesion to laminin.

The laminin-binding alpha7beta1 integrin receptor is highly expressed by skeletal and cardiac muscles, and has been suggested to be a crucial molecule during myogenic cell migration and differentiation. Absence of integrin alpha7 subunit contributes to a form of muscular dystrophy in integrin alpha7 null mice, whereas specific mutations in the alpha7 gene are associated in humans with congenital myopathy. To examine in more detail the potential role of integrin alpha7 in human-related muscular disorders, we cloned alpha7 cDNA by RT-PCR from human skeletal muscle mRNA and then expressed the full-length human integrin alpha7 cDNA by transfection in several cell lines including MCF-7, COS-7, and NIH3T3 cells. The isolated cDNA corresponds to the human alpha7X2B alternative splice form. Expression of human alpha7 was further confirmed by transfection of chimeric human/mouse alpha7 cDNA constructs. To demonstrate the functionality of expressed human alpha7, adhesion experiments with transfected MCF-7 cells have confirmed the specific binding of human alpha7 to laminin. In addition, mouse polyclonal and monoclonal antibodies were generated against the extracellular domain of human alpha7 and used to analyze by flow cytometry MCF-7 and NIH3T3 cells transfected with the full-length of human alpha7 cDNA. These results show for the first time the exogenous expression of functional full-length human alpha7 cDNA, as well as the development of monoclonal antibodies against the human alpha7 extracellular domain. Antibodies developed will be useful for further analysis of human disorders involving alpha7 dysfunction and facilitate isolation of muscle stem cells (satellite cells) and thereby expand the opportunities for genetically modified transplantation treatment of human disease.

3T3 Cells↗
PubMed2001

Abdominal wall abscess secondary to spilled gallstones: late complication of laparoscopic cholecystectomy and preventive measures.

Spilled gallstones left in the abdominal cavity or trapped at trocar sites may cause considerable morbidity. We saw a patient with an abdominal wall abscess 2 years after laparoscopic cholecystectomy secondary to spilled stones. After we reviewed the operative procedure in addition to the accumulated experience in laparoscopic surgery, we believe that retrieval of specimens and their contents is of paramount importance, especially when the gallbladder is infected, contains several stones, or may harbor malignancy. Therefore, we made use of a simple surgical glove with a long pursestring suture surrounding the opening to collect the specimen. This method proved to be simple and quite convenient, with the needed materials readily available. It can collect the spilled stones within the abdominal cavity as well as the gallbladder and can transport these stones out of the abdominal cavity with ease and safety. It also protects the specimen in contact with the wound and cuts short the operating time. The technique and advantages are described.

Abdominal Abscess↗
PubMed2000

Migration of endoclip into duodenum. A rare complication after laparoscopic cholecystectomy.

The long-term effect of spilled clips within the abdominal cavity after laparoscopic cholecystectomy is unknown. However, most surgeons agree that the migration of clips has limited clinical consequences. A few cases have been reported of clips that have migrated into the common bile duct, causing stone formation and/or obstructions. We present a case of gallstone pancreatitis treated with laparoscopic cholecystectomy that was complicated by bile leakage from the cystic duct stump 1 day after the procedure. Although the leaking stump sealed itself spontaneously after the placement of a biliary stent, a clip had migrated directly to the superior wall of the first portion of the duodenum. Herein the details of the patient's history are presented. We also discuss the possible mechanisms of clip migration and describe some preventive measures.

Bile↗
PubMed2000

Laparosopic removal of large gastric phytobezoars.

Large gastric bezoars are difficult to remove endoscopically. A 78-year-old man presenting with abdominal pain and loss of appetite for 4 months was admitted and evaluated. Gastroscopy disclosed two large phytobezoars within the stomach. Laparoscopic removal was undertaken. The bezoars were removed via a gastrotomy using the three-trocar technique. They were successfully retrieved from the abdominal cavity using an improvised "endobag" made from a simple surgical glove. Such an endobag presents several advantages; they are easy to make, sterile, economical, readily available, disposable, there is ample space to manipulate the specimen within, and there is minimal risk of contamination throughout the procedure. The authors recommend this approach for the treatment of patients with large gastric bezoars in whom laparotomy is indicated.

Abdominal Pain↗
PubMed2000

Liberal use of a bag made from a surgical glove during laparoscopic surgery for specimens retrieval.

Laparoscopic surgery has been gaining wide acceptance in recent years. Tissue removal from the abdominal cavity becomes a paramount issue, especially when the specimen is infected, contains several fragments, or potentially contains a malignancy. Several sophisticated instruments and devices have been designed for this purpose. However, most of these are expensive, difficult to handle, and come in a fixed size. Condoms, glove fingers, and zipper-type plastic bags have been tried also, but with limited success. The authors report use of a simple bag made from a surgical glove to collect specimens; a long purse-string suture surrounds the opening or the base of the glove finger to secure material during retrieval. This method has been found to be simple and convenient, and necessary construction material is readily available. The bag not only protects the specimen from contact with the wound but also cuts short the operating time. The technique and advantages are described.

Gloves, Surgical↗
PubMed1999

Laparoscopic resection of an omental cyst with pedicle torsion.

Omental cysts are the least-common variety of all types of intra-abdominal cystic lesions. In the past, transabdominal laparotomy with excision of the cyst was the treatment of choice. With the advent of laparoscopic surgery, it has become possible to resect the cyst without the need for a large incision in the abdomen. We report a case of a 15-year-old girl who underwent diagnostic laparoscopy for recurring abdominal pain of 2 years' duration. The procedure revealed a huge cyst lying above the omentum with its pedicle rising from the greater curvature of the stomach. The pedicle was noted to have twisted eight times in a clockwise direction. The cyst was resected by laparoscopic means using three trocars. The postoperative course was uneventful. As presented in this case, we believe that a laparoscopic approach is an attractive alternative for the management of omental cystic lesions.

Abdominal Pain↗
PubMed1999

Small bowel perforation caused by a sharp bone: laparoscopic diagnosis and treatment.

Small bowel perforation caused by sharp or pointed foreign bodies rarely is diagnosed preoperatively because clinical symptoms usually are nonspecific and can mimic other surgical conditions such as appendicitis and cecal diverticulitis. We report the case of a 57-year-old man who underwent diagnostic laparoscopy for abdominal pain of unknown etiology. Swelling and erythema were noted in a segment of small bowel in the right lower abdomen. A tiny sharp-pointed object was found penetrating the inflamed portion of the bowel. This foreign body was removed and the perforation immediately repaired under laparoscopic guidance. The postoperative course was uneventful. We believe that in cases of lower abdominal pain with peritoneal irritation, laparoscopy can provide not only a wide field of examination to localize intraabdominal pathology, but in some instances it can aid in case management.

Animals↗
PubMed1999

Laparoscopic appendectomy for ruptured appendicitis.

We conducted a retrospective analysis to assess the feasibility of laparoscopic appendectomy in cases of ruptured appendicitis. Between August 1993 and April 1998, a total of 328 laparoscopic appendectomies were performed in Min-Shen General Hospital. There were 34 cases of pathology-proven ruptured appendicitis. Patients were divided into three groups according to the operative findings: group 1 (10 cases) consisted of patients with a perforated appendix with local peritonitis, group 2 (15 cases) consisted of patients with perforated appendix with diffused peritonitis, and group 3 (9 cases) consisted of patients with abscess formation around the perforated appendix. Three cases in group 3 were converted to laparotomy and were excluded from this study. Mean age (+/- SD) was 30 +/- 15 years in group 1, 39 +/- 23 years in group 2, and 37 +/- 13 years in group 3. Duration of symptoms was longer in group 3 (4.2 +/-1.2 days) than in group 1 (1.8 +/- 1.3 days) and group 2 (2.3 +/- 1.2 days). There was no difference in operation time among groups 1 (52 +/- 10 min), 2 (64 +/- 13 min), and 3 (67 +/- 16 min). The time of flatus passage after operation was similar in the three groups (group 1, 17 +/- 11 hours; group 2, 21 +/- 12 hours; group 3, 24 +/- 8 hours). Hospital stay was significantly shorter in group 1 (3.0 +/- 1.1 days) than in group 2 (5.1 +/- 2.2 days) and group 3 (4.2 +/- 1.2 days). There were no complications and no readmissions. Our results indicate that the laparoscopic approach is feasible for ruptured appendicitis with local or diffuse peritonitis and in selected cases with abscess formation. However, prospective randomized controlled trials are needed to determine which procedure is to be recommended.

Adolescent↗
PubMed1997

Functional expression of the alpha 7 integrin receptor in differentiated smooth muscle cells.

Expression of the alpha7 integrin is developmentally regulated and is thought to be tissue-specific for both skeletal and cardiac muscles. We now report that alpha7 is also strongly and ubiquitously expressed by various types of smooth muscle, including vascular, gastrointestinal and genitourinary smooth muscles. In addition, alpha7 was surface-expressed by a number of smooth muscle cell lines that maintained their differentiated phenotype following adaptation to culture. Studies with the mouse 9E11G smooth muscle cell line showed that the alpha7 integrin mediated both adhesion and motility of these cells on laminin 1 substrates. Alpha7 expression appears to correlate with the smooth-muscle-differentiated phenotype. The multipotential P19 mouse embryonic stem cell line lacks alpha7 but uses the alpha6 integrin to adhere to laminin 1. Following retinoic acid-induced P19 differentiation predominantly to the smooth muscle cell lineage, high expression of alpha7 was detected along with partial dependence on alpha7 for binding to laminin. The expression of alpha7 paralleled the induction of smooth-muscle-specific alpha-actin, as revealed by dual-labeling flow cytometry. In contrast, alpha7, which initially was highly expressed on the surface of vascular smooth muscle cell explants, was rapidly downregulated in smooth muscle cell outgrowths as they dedifferentiated into their synthetic phenotype. The results indicate that the expression of alpha7 integrin in smooth muscle cells is associated with their differentiated phenotype and mediates their interaction with laminins.

Amino Acid Sequence↗
PubMed1996

Alpha7 integrin mediates cell adhesion and migration on specific laminin isoforms.

The laminin-binding alpha7beta1 integrin receptor is expressed at high levels by skeletal and cardiac muscles and by certain melanocytic cells. We have assessed the potential role of the alpha7A/B integrin isoforms in mediating cell adhesion and motility and determined the laminin isoform specificity of this integrin. When MCF-7 breast carcinoma cells, normally nonadherent to laminin 1, were stably transfected with cDNA for mouse alpha7, they adhered with high efficiency and migrated on laminin 1 substrates. Function-perturbing monoclonal antibodies generated to mouse alpha7 subunit blocked both adhesion and migration of alpha7 transfectants on laminin 1 substrates. Additional studies with MCF-7 transfectants revealed that alpha7beta1 binds well to laminin 1 and to a mixture of laminin 2 and 4 but not to laminin 5. Importantly, alpha7beta1 was capable of promoting motility on both laminin 1 and laminin 2/4 substrates. However, MCF-7 cells transfected with cDNA for either alpha7A or alpha7B showed no significant differences in cell adhesion or motility on laminin 1 substrates. Although the role for the alternatively spliced cytoplasmic variants of alpha7 remains unknown, the results establish that alpha7beta1 mediates cell adhesive activities on a restricted number of laminin isoforms.

Amino Acid Sequence↗
PubMed1996

Laminins promote the locomotion of skeletal myoblasts via the alpha 7 integrin receptor.

The alpha 7 beta 1 integrin is specifically expressed by skeletal and cardiac muscles, and its expression and alternative mRNA splicing at the cytoplasmic domain are developmentally regulated. We analyzed the role of alpha 7 integrin in mediating myoblast adhesion and motility on different laminin isoforms. Mouse C2C12 and MM14 myoblast cell lines were found by flow cytometry and immunoprecipitation to express high levels of the alpha 7 integrin. Overall expression of alpha 7 increased as the C2C12 myoblasts differentiated; myoblasts expressed only the alpha 7B cytoplasmic variant whereas in differentiating myotubes alpha 7A increased markedly. Function-perturbing monoclonal antibodies generated to alpha 7 integrin efficiently blocked both adhesion and migration of MM14 and C2C12 mouse myoblasts on laminin 1. Other studies with MM14 myoblasts showed that alpha 7 is also a receptor for laminin 2/4 (human placental merosins) but not for epithelial-cell-specific laminin 5. Blocking antibody to alpha 7 only partially inhibited adhesion to laminin 2/4 but almost completely blocked motility on this substrate. Finally, to assess the potential role of the alpha 7 cytoplasmic domain, CHO cells were stably transfected to expressed chimeric alpha 5 cDNA constructs containing the wild-type alpha 5 or the alpha 7A or alpha 7B cytoplasmic domain; all forms of the integrin showed identical activities for adhesion, migration, proliferation, and matrix assembly on fibronectin substrates. These results established that alpha 7 beta 1 receptor can promote myoblast adhesion and motility on a restricted number of laminin isoforms and may be important in myogenic precursor recruitment during regeneration and differentiation.

Amino Acid Sequence↗
PubMed1995

Growth factor regulation of integrin-mediated cell motility.

Cell motility, a primary component of tumor cell invasion, is a continuum of sequential events in which the cell extends pseudopodia, forms nascent attachments, assembles and contracts the cytoskeleton, and finally, as it translocates forward, disengages distal adhesions. What triggers cells to move? Substratum contact mediated by integrin adhesion receptors is important, but other signals such as chemokinetic factors appear to be required for continued crawling. It is now apparent that integrins do not simply bind cells to matrix in a Velcro-like fashion, but also are potent signaling molecules. Initial engagement of integrins induces their condensation into focal contacts, forming anchors to the extracellular matrix and discrete signal-transducing complexes on the cytoplasmic surface. A number of growth factors, through either autocrine or paracrine pathways, can activate the cellular machinery that mobilizes the cell. Thus, these two classes of receptors--the integrin receptors that bind specific extracellular adhesion molecules, and growth factor receptors that bind their respective ligands--can regulate cell locomotion. Not surprisingly, there is 'cross-talk' between integrin and growth factor receptors that occurs through their common intracellular signaling pathways. In this way, each receptor type can either amplify or attenuate the other's signal and downstream response. An example of growth factor-induced motility is the epithelial-mesenchymal transition induced by hepatocyte growth factor/scatter factor (HGF/SF). When bound to its receptor, the c-met proto-oncogene product, HGF/SF induces a phenotypic conversion that appears to be an important aspect of tumor progression in malignant carcinomas. The motogenic response produced by HGF/SF in carcinoma cells occurs in discrete steps in which integrins and focal adhesion kinase (p125FAK) are first recruited to focal contacts. This is rapidly followed by cell spreading, disruption of focal adhesions and cell-cell contacts, and, finally, cell crawling. The precise mechanism by which growth factors such as HGF/SF and its receptor induce this motogenic response and modulate integrin function has not been clearly defined but appears to involve several signaling pathways. Understanding the process by which growth factor and integrin receptors interact and regulate motility may suggest novel targets for therapeutic intervention.

Animals↗
PubMed1991

Rhodanese and sodium thiosulfate encapsulated in mouse carrier erythrocytes. II. In vivo survivability and alterations in physiologic and morphologic characteristics.

Biodegradable drug carrier mechanisms were employed in drug antagonism studies. Prior studies indicated that erythrocytes containing encapsulated rhodanese and sodium thiosulfate metabolized cyanide to thiocyanate in vitro. Studies were conducted to investigate the properties of these sulfurtransferase-loaded red blood cells in vivo by administering the carrier red blood cells intravenously. Approximately 40 to 50% of the cells were eliminated within the first few hours while the remaining loaded erythrocytes persisted in the circulation. The present studies were initiated to investigate the characteristics of the disposition of the loaded erythrocytes and to examine differences in the properties between carrier and noncarrier erythrocytes. Also, the disposition and viability of the erythrocytes in vivo were studied with relation to various biochemical, physiological, and morphological properties. These studies indicated that the carrier erythrocytes had a smaller cell volume and were more susceptible to hemolysis than normal erythrocytes. Morphologic studies by electron microscopy indicated that extensive morphologic changes occurred during the procedures after hypotonic dialysis, isotonicity adjustment, and resealing were completed. Differences were noted between those cells that were only resealed and those cells that were also subjected to annealing. The morphologic characteristics of most of the cells were restored to the "normal" morphologic appearance only after annealing. Annealed erythrocytes' in vivo survivability was correlated with the physical properties of these cells.

Animals↗
PubMed1990

Subpopulations of intrathyroidal lymphocytes in Graves' disease.

Subsets of T- and B-lymphocytes were immunophenotyped in frozen thyroid tissues from 20 patients with Graves' disease by using the avidin-biotin-complex peroxidase method. A panel of B- and T-cell monoclonal antibodies were employed to detect the subsets of T cells, activated T cells, natural killer cells and B cells. Serum thyroglobulin and microsomal antibodies were also measured simultaneously from both the thyroid vein and the peripheral vein in 9 patients. The quantitative results found that an almost equal ratio of lymphocytes stained positively for Leu 3a (CD4) and T8 (CD8) in almost all specimens. Activated lymphocytes expressing T9, T10, and Tac (CD25) were sporadically noted in the interstitial areas. The lymphoid aggregates and follicles were B cell clusters. Natural killer cells appear to play an insignificant role in Graves' disease. The thyroid epithelial cells expressed HLA-DR (Ia+) and HLA-ABC, suggesting a possible localized immune reaction between antigen-presenting thyroid epithelial cells and lymphocytes. The titers of serum thyroglobulin and microsomal antibodies from either the thyroid vein or the peripheral vein showed no definite correlation with the lymphoid distribution of the thyroid tissues, implying that the in situ or local immunologic reaction may not reflect the status of systemic antibody production. The immunologic mechanism and pathogenesis of Graves' disease is reviewed and discussed.

Autoantibodies↗