Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MESENTERY”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2005

Overexpression of the Del1 gene causes dendritic branching in the mouse mesentery.

In the present study, we established transgenic mice overexpressing Del1, a ligand of integrins, to examine the effect of overexpression of Del1 on vascular morphogenesis. In the wild-type mouse, mesenteric vessels are shaped like rakes consisting of a long stalk and short branches at the periphery. In contrast, those in transgenic mice showed typical dendritic architecture consisting of a few large primary branches with smaller spreading branches. The phenotype of mice overexpressing Del1 suggests the existence of a tissue-specific mechanism for branching morphogenesis in the mesentery.

Animals↗
PubMed1978

Relief of lymph obstruction by use of a bridge of mesentery and ileum.

The background to the use of a bridge of ileum with its associated mesentery in the relief of lymphatic obstruction is described. A case report of the successful use of this method in a 22-year-old patient with lymphoedema praecox is presented. Following experience with further cases, it is suggested that, provided changes in the lymph channels and in the tissues of the affected limb are not irreversibly damaged, effective drainage through small gut lymphatics may be achieved.

Adult↗
PubMed1990

Plexiform neurofibromatosis of the liver and mesentery in a child.

Plexiform neurofibromatosis of the liver was recognized by needle biopsy of the liver in an 11-yr-old boy who had a 2-yr history of diarrhea, intermittent abdominal pain, failure to gain weight and progressive abdominal distention. Imaging studies demonstrated a large retroperitoneal mass; a laparotomy was performed. At surgery, the mesentery was greatly thickened by neurofibromas, and plexiform neurofibroma extended through the hilum of the liver. Light and electron microscopy demonstrated that in addition to the direct involvement by tumor, neural hyperplasia existed throughout the liver. The most distal ramifications of the portal spaces were filled with Schwann cells, bundles of unmyelinated nerves and perineurium-surrounded nerves containing myelinated and unmyelinated fibers. The ultrastructural findings were consistent with stimulation of proliferation of all the portal neural elements and tumoral tissue. The nontumoral response was more than simple hyperplasia because it appeared to result in fibrotic changes in the most involved areas and active breaching of the limiting plate with destruction of hepatocytes and collagen deposition throughout the liver.

Biopsy, Needle↗
PubMed1985

Tumor-associated desmoplasia in the rabbit mesentery characterized by morphological, biochemical and cytophotometric methods.

Intraperitoneal implantation of V2 carcinoma cells in the rabbit leads to invasion of the mesentery and to structural tissue alterations which are concomitantly of a destructive and a desmoplastic type. In this report, we describe the desmoplastic changes which are characterized by the increased formation of collagen and of proteoglycans resulting in an increased thickness of the membrane. Biochemical data indicate that the total amount of collagen increases with time after implantation, whereas the relative amount per unit of dry weight, as well as the contributions of type I (15-25%) and type III (6-8%), stay within the same range. The increased synthesis of extracellular matrix is accompanied by a change in the appearance of the fibroblasts which now show the morphologic features of synthesizing cells. Also, an appreciable number have entered the S-phase. We propose that the desmoplastic changes are tumor-associated, since implantation of epithelial cells from normal rabbit liver does not result in similar alteration. Our findings are discussed in view of the role played by tumor and/or host cells in the increased production of extracellular matrix, of possible factor(s) elaborated by the tumor cells, and of the general significance of desmoplastia for tumor spread.

Animals↗
PubMed1985

Malignant smooth muscle tumors of the retroperitoneum and mesentery: a clinicopathologic analysis of 44 cases.

Forty-four cases of leiomyosarcoma arising in the retroperitoneum (33 cases) and mesentery (11 cases) were analyzed clinicopathologically, and four were examined ultrastructurally. These tumors were more common in women (61%) than in men (39%), and the median age of the patients was 59 years. Except for three tumors, most were large and over 10 cm in the greatest diameter. Twenty-seven tumors were classical leiomyosarcomas, while seven were composed predominantly of epithelioid cells and classified as malignant leiomyoblastoma (epithelioid leiomyosarcoma). In addition to the classical microscopic features, dedifferentiated areas resembling malignant fibrous histiocytoma were noted in three cases. Ultrastructurally, the tumors were characterized by smooth muscle tumor cells showing a spectrum of differentiation of varying degrees. Of the 42 patients for whom follow-up information could be obtained, 33 (79%) died within a period of five years after the initial treatment. Mitotic activity showed no significant correlation with biological behavior; ten of the 15 patients in whom the mitotic counts were less than five per 10 high-power fields (HPF), expired of the tumor.

Adult↗
PubMed1994

Regional differences in spontaneously occurring angiogenesis in the adult rat mesentery.

Despite intensive study in the area of angiogenesis, relatively little is known about normal angiogenesis in adult animals. Preliminary studies using the Griffonia simplicifolia I (GSI) lectin as a microvascular marker indicated that capillary sprouting occurs in the clear "windows" of normal intact adult rat mesentery. The purpose of this study was to determine whether angiogenesis occurs uniformly within the mesenteric windows and whether maturational age affects the extent of angiogenesis in the absence of any experimental or pathological perturbation. Four groups of female Sprague-Dawley rats were used, "weanling" (4-5 weeks), "juvenile" (6-8 weeks), "young adult" (10-13 weeks), and "adult" (16-20 weeks). Microvessels sprouting into proximal and distal windows were delineated in whole mounts by use of fluorescent derivative of the GSI lectin. Microvascular sprouting, indicating angiogenesis, was found in all age groups, but was most frequent in the windows sampled from the distal region of the small intestine when compared with those from the proximal region. The mean number of microvessels per sample site was significantly higher in the distal windows of adults than in the weanling or juvenile rats. Angiogenesis was found to occur asymmetrically within the individual windows in the two adult groups, with significantly more angiogenesis on the intestinal side compared to that along the portal vessels. We conclude that there is an age-related increase in angiogenesis into the mesenteric windows, and that the intestinal side is more prone to spontaneous angiogenesis than is the portal side.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1997

Mechanism of macromolecule concentration in collecting lymphatics in rat mesentery.

The mechanism by which macromolecular contents are concentrated during lymph transport was investigated in the collecting lymphatics of the mesentery of the rat. To examine changes in the concentration of lymph macromolecular tracer (fluorescein isothiocyanate-tagged dextran, MW 148,900) in the rhythmically contractile lymphatics, we quantified the fluorescence intensity of the lymph tracer using an intravital microscopy system with single slit-laser (20 microns in thickness) epi-illumination, regardless of the vasomotion of the lymph vessel. The results for the fluorescence intensity measurement at different sites at distances of about 300-1000 microns along unbranched collecting lymphatics revealed that the concentration of the lymph macromolecular contents was significantly increased during their passage from upstream to downstream (P < 0.05). The fluorescence intensity of lymph tracer in the occluded segment of collecting lymphatics around 1000 microns in length was enhanced during the contraction phase and reduced during the relaxation phase. These results suggest that the filtration of macromolecule-free fluid from the lymph across the lymphatic wall during its contraction plays an important role in the lymph concentration mechanism in the collecting lymphatics, probably due to the Starling forces acting across the lymphatic wall.

Animals↗
PubMed1993

Oxyradical generation from leukocytes during endotoxin-induced microcirculatory disturbance in rat mesentery--attenuating effect of cetraxate.

By using the intravital microscope equipped with digital imaging processor, we investigated the granulocyte-mediated oxidative burst during the endotoxin-induced microvascular derangement in rat mesentery. The leukocyte behavior after the injection of acridine orange was detected by using a silicon-intensified target camera, the erythrocyte velocity was measured by using a high-speed video camera system, and the luminol-dependent photoemission was visualized by an ultrasensitive photon-counting camera in lipopolysaccharide (LPS)-treated microvascular beds. At 60 min after the LPS administration, a significant leakage of FITC-labeled albumin was observed along mesenteric venules under a fluorescence microscopy. The number of sticking leukocytes increased in association with the decrease in erythrocyte velocity after starting the LPS infusion. The luminol-dependent chemiluminescence in microvascular beds gradually increased over that recorded prior to LPS exposure and was fourfold higher 60 min after the start of LPS infusion. The distribution of the photoemission clearly corresponded to the venular endothelium, to which leukocytes adhered. In blood samples taken from the mesenteric vein at 60 min after the LPS administration, a decrease in the number of granulocytes and increases of total and individual chemiluminescence activities were observed. These results suggest that LPS induces oxidative burst from granulocytes on the venular endothelium. Cetraxate, an inhibitor of proteases including plasmin, significantly inhibited the leukocyte activation and prevented alterations in microvascular hemodynamics induced by LPS in vivo, whereas it had no effect on the LPS-induced oxyradical generation from adherent leukocytes in vitro. The present study demonstrates that proteases such as plasmin may play an important role in the pathogenesis of endotoxin-induced microvascular disturbances.

Animals↗
PubMed1995

Nitric oxide mediates microvascular permeability in the isolated perfused rat mesentery?

The permeability influencing effect of nitric oxide was studied by means of an isolated perfused mesentery preparation in combination with a intravital/fluorescence microscopic set up. As a fluorescent marker served FITC-dextran mol wt 70,000 daltons. Tissue treatment was performed by application of NO-donors like SNP or GTN. Additionally the effects of bradykinin, L-nitroarginine or the combination of both were tested in regard to a permeability modulation. The results point out that NO-donors did not enhance microvascular permeability, whereas the permeability increasing effect of bradykinin is mediated by an NO-independent pathway.

Animals↗
PubMed1984

Cellular and extracellular changes following mast-cell secretion in avascular rat mesentery. An electron-microscopic study.

Mast cell (MC) secretion induces local cell proliferation lasting 48-72 h in fibroblasts and mesothelial cells in the almost avascular true mesentery of the rat. We studied this membranous tissue by transmission electron microscopy with regard to cellular and extracellular features occurring during the first 72 h following MC secretion. After MC secretion elicited by compound 48/80, apparently all individual tissue-bound cells (i.e. fibroblasts, mesothelial cells, and macrophages) show signs of accelerated metabolic activity. In fibroblasts, conspicuous increases in the volume of Golgi apparatus and rough endoplasmic reticulum and in the amount of plasmalemmal indentations suggest an increased production and secretion of the extracellular matrix. Released MC granules lying close to projections of nearby phagocytosing cells cause areas free from electron-dense material in the extracellular matrix. MC secretion therefore appears to produce a remodelling of extracellular matrix. Most of the activities initiated by MC secretion start to subside within (48-)72 h. The findings indicate a close functional relationship between the tissue MC and all its neighbouring cells and the surrounding extracellular matrix. The striking chain of events that it induces emphasizes strongly that the secreting MC plays a prominent although as yet in many respects enigmatic role in normal tissue.

Animals↗
PubMed1984

Blood-nerve barrier in the Vater-Pacini corpuscle of cat mesentery.

Correlated thin-section, freeze-fracture and tracer examinations were used to examine the blood-nerve barrier of the Vater-Pacini corpuscles in cat mesentery. A laminar inner core and a multilayered outer core enfolded the terminal nerve fiber of the corpuscle. The lamellar cells of both cores were characterized by numerous vesicular membrane invaginations. Freeze-fracture images and tracer experiments employing lanthanum nitrate proved that these invaginations are static structures mediating in neither active pinocytosis nor the transcellular transport of metabolites. In both inner and outer cores, lamellar cells were connected to one another by tight junctions of either the zonula or the fascia type, that occurred between lamellar-cell processes within the lamella and between the cells of adjacent lamellae. Intravascularly applied lanthanum lay at the outermost regions of the corpuscles without entering their internal zones, apparently because lamellar-cell tight junctions hindered further penetration. The results of our investigations suggest strongly that the Vater-Pacini corpuscle lamellae enfolding the nerve terminal form an effective diffusion barrier against the permeation of tissue fluids, thus preserving the corpuscle internal circumference.

Animals↗
PubMed1979

Effect of hemodilution and hemoconcentration on red cell flow velocity in the capillaries of the rat mesentery.

Erythrocyte velocities in capillaries of rat mesentery were measured during systemic normotension and hypotension over a range of hematocrit from 0.31 +/- 0.06 to 0.58 +/- 0.04. Velocity was measured according to the method of Tompkins, Monti and Intaglietta. The hematocrit was varied by isovolemic exchange of blood with 4.5 g% albumin solution (bovine) or packed red cells (Hct. approximately 0.9). Hypotension was induced by hemorrhage to a preselected pressure of about 35 mm Hg. Under normotension red cell velocity stayed almost constant over a range of Hct. from 0.31 +/- 0.07 to 0.58 +/- 0.09. However, during hypotension significant differences were found for control animals (Hct. 0.43 +/- 0.07), hemodiluted animals (Hct. 0.31 +/- 0.06), and hemoconcentrated animals (Hct. 0.58 +/- 0.04). Velocities amounted to 36 +/- 21%, 52 +/- 24%, and 29 +/- 27% respectively, compared to control velocity. These marked differences in red cell velocities are explained by the strong effect of the hematocrit levels on apparent blood viscosities. It is assumed that the post-capillary microvascular bed is the site where the hematocrit level will affect apparent blood viscosity most intensively.

Animals↗
PubMed1980

Effect of reduced red cell "deformability" on flow velocity in capillaries of rat mesentery.

A graded reduction of "deformability" of red blood cells (RBC's) of rats was obtained by treatment with the SH-oxidizing agent, diamide. Rigidified RBC's were injected into rats by isovolemic exchange against 60% of the native RBC's and RBC flow velocities in capillaries of rat mesentery measured. At normal mean arterial pressure RBC flow velocity decreases by 29% in rats receiving cells rigidified with 0.5 mmol . 1(-1) diamide. Surprisingly a further rigidification of erythrocytes by 1.5 mmol . 1(-1) diamide results in a decrease of flow by only 15%. During hypotension RBC flow velocities dropped precipitously to 8 +/- 15% for the 0.5 nmol . 1(-1) and to 2 +/- 6% for the 1.5 mmol . 1(-1) diamide group compared to velocities during normotension. By microscopy we observed a stop of flow in many vessels. This result outlines the importance of a normal red cell "deformability" for the maintenance of sufficient perfusion of the microcirculation, in particular at low blood pressure gradients.

Animals↗
PubMed1977

Isolation and study of functional mast cells from lung and mesentery of the guinea pig.

A method is described for the dissociation of guinea pig lung and mesentery into their component cells. The method comprises incubation of the tissues with the enzyme pronase in Ca++- and Mg++-free saline followed by mechanical dispersion and yields on average 3-8% free mast cells. These cells are morphologically intact and viable. They retain an active sensitization or can be passively sensitized. The levels of cAMP and cGMP in the whole cell suspension respond to catecholamine, histamine or cholinergic stimulation in a way similar to that observed in the corresponding undispersed tissue. Although the separation of guinea pig mast cells from other cells proved to be more difficult than the purification of rat mast cells, an inrichment of greater than 50% has been achieved. The mast cells isolated by this method proliferate in vitro and have been cultured successfully for several months.

Anaphylaxis↗
PubMed1991

Experimental mast cell activation improves connective tissue repair in the perforated rat mesentery.

The participation of mast cells in connective tissue repair was studied using the perforated-rat-mesentery model. Perforation of mesenteric membranes was performed during laparotomy of anesthetized Sprague-Dawley rats. Laparotomy significantly reduced the histamine content of the mesenteric membranes on day 1 postoperatively and perforation as such reduced the histamine content even more on days 1-10. Mast cell activation induced by a single intraperitoneal injection of Compound 48/80 two days prior to operation, significantly improved healing on days 5-7 postoperatively. Daily injections of Compound 48/80 for 5 days prior to operation showed significantly better healing compared to such injections for five days postoperatively. Administration of lupitidine, a long acting histamine H2-receptor antagonist, two times daily starting on the day of 48/80 injection to day 4 after operation did not apparently affect healing. The results indicate that mast cells may be activated during normal wound healing and that a preoperative, pharmacological activation improves healing. Furthermore, histamine does not seem to be of major importance for the beneficial effect of such mast cell activation on connective tissue repair.

Animals↗
PubMed1980

[Rupture of intestine and mesentery due to fall from height (author's transl)].

Twenty-five cases of falls from heights are reported under the aspect of lesions of the intestinal tract depending on height of fall and impact. Rupture of mesentery occurred in five cases, in only one case a rupture of intestinal wall. The results verify the thesis, asserted in a recent investigation of injuries caused by maltreatment: direct and not indirect forces lead to isolated lesions of intestinal tract.

Accidents↗
PubMed1989

Cystic teratoma of the mesentery.

Cystic teratoma is an unusual cause of mesenteric/omental cysts. A case of cystic teratoma of the mesentery in a 5-year-old girl is reported.

Child, Preschool↗
PubMed1986

Inflammatory pseudotumor of the mesentery and small intestine.

Three cases of abdominal inflammatory pseudotumor or inflammatory myofibroblastic tumor of the small intestinal mesentery are presented with additional examples from the literature. An abdominal mass was detected in three preadolescent children who presented with fever, growth failure, hypochromic anemia, thrombocytosis and polyclonal hypergammaglobulinemia. The radiographic findings confirmed the presence of a mass. Following surgical resection, the systemic manifestations dramatically resolved. The solid mesenteric mass was composed of spindle cells with the features of myofibroblasts and mature plasma cells and small lymphocytes. Clinical follow-up confirmed the benign nature of this lesion with no signs of recurrence in any patient from 3 to 6 years after the initial surgery.

Child↗