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Biomedical subjects

C Simopoulos

Publications and source records attributed to C Simopoulos.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression of laminin, type IV collagen and fibronectin molecules is related to embryonal skin and epidermal appendage morphogenesis.

Basement membrane zones are specialized sheets--like arrangements of extracellular matrix proteins and glycosaminoglycans, and act as an interface between parenchymal cells and support tissue. They separate epithelium, endothelium, muscle cells and Schwann cells from adjacent connective tissue stroma, and also from a limiting membrane in the central nervous system. They are involved in several cellular and biological processes, including adhesion, migration and cellular differentiation. Basement membranes have five major components: collagen type IV, laminin, heparan sulfate, entactin, and fibronectin. In addition, there are numerous minor and poorly characterized protein and glycosaminoglycan components. The various components of the basement membranes of the skin (collagen type IV, proteoglycans--heparan sulfate, laminin, entactin and fibronectin) are products of the epithelial (epidermal) cells. We studied immunohistochemically the origin, the first appearance and distribution of the adhesive extracellular glycoprotein laminin and the fibrillar proteins of the extracellular matrix collagen type IV and fibronectin in the basement membranes of fetal human skin between 12 to 21 weeks of gestational age. Additionally, we studied the expression of vimentin in the extracellular matrix of the epithelial/mesenchyme junction of the skin. This study demonstrates clearly that the expression of the antigens laminin, collagen type IV and fibronectin starts in the germinative epithelial cells of the skin at the bulbs of the hair follicles (12th week for fibronectin and 19th week for laminin and collagen type IV), and migrating progressively involves the epithelial epidermal cells of the covering skin, as well as, the basement membrane at the dermal-epidermal junction in that region (between 20 to 21 weeks of gestational age).

Collagen Type IV↗
PubMed2001

Expression of the intermediate filament vimentin and fibrillar proteins of the extracellular matrix related to embryonal heart development.

During organogenesis, the heart is one the first organs to develop and the earliest organ to function. The early appearance of cardiac activity in the tubular hearts of chick and rat embryos was noted many years ago. It arises from two plates of the splanchnic mesoderm which fuse to form a single tubular structure composed of endocardial and myocardial cells and, between them, the extracellular cardiac matrix. There is considerable variation in the formation of the extracellular matrix in the various regions of the heart during development. The endocardial lining cells of the vertebrate embryos show a regional specificity that remains an unexplained phenomenon in cardiac morphogenesis. The great majority of the endocardial lining cells remain epithlial. However, a restricted population of endothelial cells, lining the atrioventricular (AV) canal and the reputed proximal outflow tract (OT), transforms into mesenchyme; the latter being the reputed progenitor of the valves and membranous septa. The purpose of this study was to investigate the extracellular cardiac matrix of the human fetal heart in different regions and in various stages of development, and also the heterogeneity of the endocardial cell lining, in connection with the endothelial cells of other cardiac vessels. Identification of the mesenchymal cells/extracellular matrix was confirmed by immunohistochemical techniques using the following monoclonal antibodies: actin, desmin, vimentin, collagen IV and fibronectin. The present results provide evidence that the extracellular matrix of the heart is of mesodermal origin but at the level of the valves the mesenchyme is derived from the endothelial lining cells rather than the primitive mesenchyme.

Antibodies, Monoclonal↗
PubMed2001

Intraperitoneal air in the diagnosis of blunt diaphragmatic rupture.

We present here a case of blunt traumatic right hemidiaphragmatic rupture with hepatic hernia that was diagnosed preoperatively on the basis of clinical, chest radiogram, and computed tomography scan suspicions. We proposed that the presence of free intraperitoneal air without guarding or peritoneal signs should be considered to be a clinical indication of hemidiaphragmatic rupture with pneumothorax.

Accidents, Traffic↗
PubMed2001

Differential expression of alpha-smooth muscle actin molecule in a subset of bone marrow stromal cells, in b-cell chronic lymphocytic leukemia, autoimmune disorders and normal fetuses.

Lymphocytes are a constituent of normal marrow. Both B and T lymphocytes are derived from bone marrow stem cells. Lymphocytes are found in normal marrow as single cells and in lymphoid aggregates or follicles. Lymphocytes and precursors are particularly prominent in bone marrow from children in which they may account for up to 40% of the bone marrow cells. The development of hematopoetic cells within the bone marrow (BM) occurs in intimate association with cells of the bone marrow microenvironment. This phenotypically diverse population of connective tissue-type cells includes fibroblasts, macrophages, adipocytes and endothelial cells and, collectively, represents the stromal tissue of the bone marrow. The presence of myoid cells in human bone marrow has been observed during hemopoiesis in embryonic life, whereas during adult life, it is strictly related to different pathologic conditions such as metastatic carcinoma, Hodgkin's disease, hairy cell leukemia and chronic myelo-proliferative diseases. Under normal circumstances, lymphoid cells may constitute up to 20% of the population of nucleated cells in the bone marrow. However, there may be an absolute or a relative increase, the latter due to a reduction in hematopoietic tissue, as in some skeletal areas in advancing age, or in hypoplastic conditions. The aim of this study was to examine the presence, distribution and quantitation of cells expressing alpha-smooth muscle actin in the stroma of the BM of patients with nodular type b-cell chronic lymphocytic leukemia (B-CLL), patients with autoimmune disorders and embryos (gestational age 15 to 25 weeks). For this reason, we investigated the presence of myoid cells (MCs) in a series of 20 trephine bone marrow biopsies from adult patients and ten fetal specimens of the spine and femur, using a monoclonal antibody recognizing alpha-smooth muscle actin, a contractile microfilament expressed exclusively by smooth muscle cells, myofibroblasts and related cells. The results of our study showed that: 1. BM stromal myoid cells represent a distinct subpopulation of reticular cells in the bone marrow, undergoing cytoskeletal remodeling in response to various stimuli (fetuses). 2. The appearance of BM stromal myoid cells is not only seen as a characteristic feature in B-CLL, but is also seen, to a lesser degree, in the stroma of bone marrow in patients with autoimmune disorders. 3. Stromal cells with phenotypic smooth muscle features appear in bone marrow during pathological situations in a manner reminiscent of what occurs during normal development.

Actins↗
PubMed2000

Intraperitoneal abscess after an undetected spilled stone.

Gallbladder perforation with loss of calculi in the abdomen is frequent during laparoscopic cholecystectomy and can cause serious late complications. We report on a 65-year-old woman who underwent laparoscopic cholecystectomy for gallbladder empyema, during which a stone spilled into the peritoneal cavity. The spilled gallstone was not noticed during the initial operation. Three months later, she reported left upper quadrant pain of recent onset without associated symptoms such as fever, nausea, or weight loss. On examination, a palpable 2-cm tender subcutaneous mass was found. Abdominal ultrasound demonstrated an incarcerated hernia, and computed tomography (CT) scan showed an intraperitoneal abscess located in the back of the anterior abdominal wall in the left upper quadrant, which contained a recalcification figure. The patient was brought to surgery, at which time an incision was made over the mass. A chronic abscess in the back of the abdominal wall, also spreading into the subfascial space, was drained, and purulent material was obtained with a large stone, 2.8 cm in diameter, which had become lodged in the rectus abdominis after an undetected stone spillage during laparoscopic cholecystectomy. The patient continued receiving antibiotic treatment for 7 days, recovered well, and was discharged 7 days after drainage of the abscess.

Abdominal Abscess↗
PubMed1994

Effect of different combinations of antibiotics on experimental septic peritonitis in rabbits.

This study was undertaken to evaluate the efficacy of different combinations of antimicrobial agents in the treatment of experimental septic peritonitis. Two hundred rabbits, divided into ten groups of 20 rabbits each, were used. Septic peritonitis was provoked in two stages: treatment of animals by mechanical lavage or antibiotics was performed during the first stage; blood cultures, isolation and identification of aerobic and anaerobic bacteria in the peritoneal cavity were performed during the second stage. The parameters assessed were survival and, in the second phase, the formation of peritoneal abscesses. The most significant finding was noted in the first phase, where diffuse peritonitis took place, with a very high mortality rate due to bacteremia and sepsis. In both blood and pus from the peritoneal cavity cultures in all groups, Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis (among the aerobes) and Bacteroides fragilis, Clostridium sp. and Peptostreptococcus sp. (among anaerobes) were the predominant pathogens identified. High mortality rates appeared to be due to the aerobic microbes, particularly Escherichia coli, whereas abscess formation was related to the anaerobes, particularly Bacteroides fragilis. All antibiotics tested were effective, whether alone or in combination. Metronidazole, however, was the most effective in the reduction of intraabdominal abscesses. The lowest mortality rate was observed in animals injected with piperacillin and a combination of cefoxitin and an aminoglycoside with metronidazole. Finally, good peritoneal lavage seemed to be as effective as any combination of antibiotic treatment.

Animals↗