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PubMed1977

Different proliferative responsiveness of fibroblasts and mesothelial cells in the rat mesentery following administration of compound 48/80 at various hours of the day.

The proliferative responsiveness of fibrolasts and mesothelial cells in the mesenterial membrane of normal rats was studied quantitatively after a single i.p. injection of the mast-cell activating and histamine-releasing drug Compound 48/80. To make some allowance for a possible chronobiologic effect of the circadian type on the induced proliferation, the drug was given at 1 a.m., 9 a.m., or 5 p.m., and the animals were examined 16, 24, and 32 h later. The proliferation was estimated by cytophotometric Feulgen DNA measurements in individual fibroblast and mesothelial cell nuclei, and by mitotic frequency counting. The main result was that a larger fraction of fibroblasts than of mesothelial cells was stimulated to proliferation, regardless of the hour of treatment with Compound 48/80. It was further demonstrated that in control animals the fraction of cells of either fibroblastic or mesothelial type present in the S cum G2 cell-cycle phases varied markedly at different hours of the day. Quantitative differences appeared in the induced proliferation with regard to the hour of treatment. The most vigorous proliferative response appeared after administration of the drug at 9 a.m. The fraction of cells in the S cum G2 cell-cycle phases was then increased at 16 h and the fraction of dividing cells at 24 h after treatment, illustrating the promptness of the induced proliferative reaction.

Animals↗
PubMed1985

Lack of mast cell reactivity during leukemic infiltration of the rat mesentery under syngeneic and allogeneic conditions. A study by transmission electron microscopy (TEM).

The ultrastructural morphology of mast cells localized in rat mesenteries was studied after intraperitoneal implantation of L5222 rat leukemia cells in syngeneic and allogenic hosts. It became evident that the mast cells in the syngeneic (BDIX rat) as well as the allogeneic system (BN rat) showed nor morphological alterations. Degranulation was never observed. This is in contrast to the behavior of macrophages which displayed a strong phagocytotic activity in allogeneic hosts. Thus, it seems that mast cells, under the present experimental conditions, remained inactive during a phase of intense tumor rejection.

Animals↗
PubMed2006

Contribution of mesenterial muscle dedifferentiation to intestine regeneration in the sea cucumber Holothuria glaberrima.

Holothurians (sea cucumbers) have been known from ancient times to have the capacity to regenerate their internal organs. In the species Holothuria glaberrima, intestinal regeneration involves the formation of thickenings along the free mesentery edge; these thickenings will later give rise to the regenerated organ. We have previously documented that a remodeling of the extracellular matrix and changes in the muscle layer occur during the formation of the intestinal primordium. In order to analyze these changes in depth, we have now used immunocytochemical techniques and transmission electron microscopy. Our results show a striking disorganization of the muscle layer together with myocyte dedifferentiation. This dedifferentiation involves nucleic activation, disruptions of intercellular junctions, and the disappearance of cell projections, but more prominently, the loss of the contractile apparatus by the formation and elimination of spindle-like structures. Muscle dedifferentiation can be seen as early as 2 days following evisceration and continues during the next 2 weeks of the regeneration process. Dedifferentiation of myocytes might result in cells that proliferate and give rise to new myocytes. Alternatively, dedifferentiating myocytes could give rise to cells with high nuclear-to-cytoplasmic ratios, with some being eliminated by apoptosis. Our results, together with those in other regeneration models, show that myocyte dedifferentiation is a common event in regeneration processes and that the dedifferentiated cells might play an important role in the formation of the new tissues or organs.

Animals↗
PubMed2006

Technique for instant stapling of the sigmoid mesentery and mesorectum in laparoscopic colorectal surgery.

BACKGROUND: Dissection of the mesentery of the distal sigmoid or rectum before transection with a linear stapler in laparoscopic colorectal surgery is time consuming, can cause irritating bleeding, and can harm the vascularization of the distal part of the bowel anastomosis. METHODS: A new linear stapling technique in laparoscopic colorectal surgery is presented. This technique is used to perform transection of the distal sigmoid or proximal rectum with a linear stapler by instant stapling of both the mesentery/mesorectal fat and the intestine instead of standard preliminary dissection. This technique was performed in a pilot study of 27 laparoscopic colorectal operations for benign or malignant disease. RESULTS: In none of the 27 patients was leakage of the anastomosis observed. CONCLUSIONS: This new technique is safe and effective. It saves time, avoids troublesome dissection of the mesentery/mesorectum, which can cause bleeding or damage to the bowel, and preserves vascularization of the distal part of the anastomosis.

Adult↗
PubMed2003

Gastrointestinal stromal tumor of the rectal mesentery.

We report a case of gastrointestinal stromal tumor (GIST) arising from the rectal mesentery. GIST of the large intestine is a rare tumor that accounts for only 0.1% of all colorectal cancers. The patient presented to our hospital with constipation and abdominal distension. Computed tomography (CT) revealed a huge mass in the pelvic cavity, and laparotomy disclosed diffuse peritoneal dissemination from the primary tumor. Radiochemotherapy was commenced, but the patient became too ill to complete it and died of the disease 2 months after surgery. A large high-grade tumor with diffuse dissemination was recognized as an indicator of poor survival in this patient.

Aged↗
PubMed2004

Intestinal obstruction in the terminal ileum caused by an anomalous congenital vascular band between the mesoappendix and the mesentery: report of a case.

We report a case of intestinal obstruction caused by a congenital abnormal vascular band in a 17-year-old boy. The patient was admitted with acute colicky abdominal pain, and an emergency laparotomy revealed that the ileum was strangulated by a fibrous band with vessels about 2 mm in diameter and 7 cm in length, extending from the antemesenterium of the terminal ileum to the mesoappendix. The affected intestine was resected with the band and the appendix. Histologically, the fibrous band was composed of loose connective tissue containing arteries, veins, and nerve fibers, suggesting that it was congenital and originated from a remnant of the ventral mesentery in the embryonic period. There have been few reports of intestinal obstruction being caused by a congenital vascular band, especially in patients beyond the pediatric age group.

Abdominal Pain↗
PubMed2005

Inflammatory myofibroblastic tumor of the ileocecal mesentery mimicking abdominal lymphoma in childhood: report of two cases.

An inflammatory myofibroblastic tumor is an uncommon benign tumor located in various organs that can be misdiagnosed as a malignant neoplasm. We herein present two patients with ileocecal inflammatory myofibroblastic tumors. An abdominal mass was detected in a 13-year-old girl and a 15-year-old boy who presented with paleness, fatigue, intermittent fever, and night sweating. The radiological findings confirmed a mass originating from the ileocecal region. The presumptive diagnosis was Burkitt's lymphoma. The histopathological diagnosis was inflammatory myofibroblastic tumor. After a surgical resection, all systemic symptoms rapidly resolved. Inflammatory myofibroblastic tumor is a rare pseudosarcomatous clinical and pathological entity. Although this tumor is more commonly reported in the lung, it can be detected in extrapulmonary sites, including the mesentery. Because the choice of treatment for this tumor is conservative surgery, an accurate preoperative analysis is important to avoid any unnecessary aggressive surgical intervention or other therapeutic approaches.

Abdominal Neoplasms↗
PubMed2002

Giant cystic lymphangioma of the small bowel mesentery: report of a case.

We herein describe the case of a 48-year-old man who presented to our hospital with abdominal distension and pain. Preoperative studies including abdominal ultrasonography and computed tomography failed to determine the cause of the pain. At laparotomy, a giant cystic tumor of the small bowel mesentery was found. Histologically, the tumor was diagnosed as a cystic lymphangioma. Although mesenteric lymphangiomas are rare, especially in adults, they should be considered as a possible cause of acute abdomen.

Abdomen, Acute↗
PubMed1990

Isolation of fatty acid amide as an angiogenic principle from bovine mesentery.

Erucamide (13-docosenamide) was found to be the major bovine mesentery angiogenic lipid as assessed by chorioallantoic membrane (CAM) assay. Two micrograms of this lipid caused angiogenesis in the assay. Angiogenic activity of this naturally occurring lipid was also found by rat corneal micropocket and mouse dorsal air-sac assays. Specificity of the chemical structure which elicited activity was low, however. The mechanism of angiogenic activity is unknown and this lipid does not promote proliferation of endothelial cells or induce inflammatory effects.

Angiogenesis Inducing Agents↗
PubMed1975

Agenesis of the dorsal mesentery without jejunoilial atresia ("apple peel small bowel").

Agenesis of the dorsal mesentery with apple peel or Christmas tree deformity but without small-bowel atresia can occur beyond the neonatal period. The recognition of this entity is imperative as it is also associated with a marginal artery which may be the only blood supply to the majority of small bowel. Preservation of this vessel is necessary to avoid catastrophic bowel death.

Child, Preschool↗
PubMed1986

The radial protein concentration profile in the interstitial space of the rat ileal mesentery.

The radial distribution of the protein concentration in the interstitium between arteriolar and venular vessels of the ileal mesentery of the rat was examined. Protein mass was determined by means of uv ultramicrospectrophotometry (UMS) and the relative volume distribution by means of fluorescence microscopy (FM) using the Na fluorescein and FITC-dextran (10,000 mol wt). UMS revealed gradients for protein mass from the vessels out into the interstitial space. FM showed a uniform distribution of fluorescence in the interstitium between the vessels. A gradient for protein mass without a gradient for volume distribution signifies the presence of a concentration gradient for protein in the interstitial space. The protein concentration across the arteriolar wall drops from 5.4 +/- 0.24 (SD) to 2.6 +/- 0.65% and across the venular wall from 5.4 +/- 0.24 to 3.3 +/- 0.43%. From the perivascular site the protein concentration declines exponentially reaching a minimum average interstitial concentration of 1.6 +/- 0.56%. Minimal protein concentration occurred at a point 37 +/- 6.4% of the 295 +/- 37 micron distance from the arteriolar to the venular vessels. In view of this distribution, it is unlikely that lymph or direct samples of interstitial fluid are representative of the perivascular protein concentration.

Animals↗
PubMed1987

Leukocyte-endothelium adhesion: microhemodynamics in mesentery of the cat.

The effects of leukocyte-endothelium adhesion on microhemodynamics were studied in cat mesentery under control conditions and following tissue suffusion with the chemotactic agent N-formyl-methionyl-leucyl-phenylalanine (FMLP). The results indicate that under normophysiological conditions there is little or no leukocyte-endothelium adhesion in arterioles and venules. Tissue suffusion with FMLP significantly increases the number of adhering leukocytes in venules, but not in arterioles. Analysis of the number of adhering leukocytes (in venules) as a function of wall shear rate suggested that increased adhesion of leukocytes was primarily due to elevated adhesive forces and not the result of decreases in dispersal forces, i.e., wall shear stress. From measurements of upstream to downstream pressure drop, red cell velocity, and microvessel hematocrit in 16 unbranched venules, no significant changes in diameter (mean of 39.9 +/- 7.8 (SD) micron), intravascular pressure gradient (0.59 +/- 0.40 X 10(-2) cm H2O/micron), nor microvessel hematocrit (31.0 +/- 9.8%) occurred in response to FMLP. There were significant decreases in upstream pressure (8%) and estimated bulk flow (28%) as well as significant increases in the number of adhering leukocytes, from 1.5 +/- 2.8 to 11.4 +/- 8.3 cells/100 micron, and vessel resistance (81%). Changes in hemodynamics were found to be more pronounced in venules with small diameters. The observed response to FMLP suggests that changes in hemodynamics during leukocyte-endothelium adhesion can be accounted for by a decrease in the effective diameter due to obstruction of the lumen by WBCs, and that adhesive interactions between WBCs and endothelium are a major determinant of blood flow resistance in the microcirculation.

Animals↗
PubMed1993

Renal angiomyolipoma associated with neurofibromatosis and primary carcinoid of mesentery.

A patient with von Recklinghausen's disease manifested by dermal neurofibromatosis and cafe-au-lait spots presented with complaints of malaise, weight loss, lower extremity weakness, and a palpable left lower abdominal quadrant mass. Evaluation revealed a lumbar neurofibroma, a localized primary carcinoid tumor of the mesentery, and a left renal angiomyolipoma. Although an association between neurofibromatosis and carcinoid has been previously reported, we believe this is the first report documenting the association of all three entities.

Carcinoid Tumor↗
PubMed1979

The permeability coefficient of albumin of the isolated rat mesentery. Modification by some mediators of inflammation, cyclic AMP and calcium.

In order to study the mechanisms whereby mediators of inflammation exert their exudative effects, we used isolated rat mesentery placed as a separation membrane between the two compartments of a diffusion cell. In this experimental arrangement, the permeability coefficient of albumin (PA) can be easily computed from the equilibration rate of 125I-labelled albumin added to one compartment. Histamine, bradykinin, serotonin and prostaglandins A1, A2, E1, E2, F1 alpha and F2 alpha all increased PA to some extent, the maximal values being approx. +60%. Dibutyryl-cyclic AMP, theophylline and isoproterenol also increased PA, thus suggesting involvement of cyclic AMP. Direct measurements of this nucleotide confirmed this hypothesis; furthermore, a linear relation between cyclic AMP levels and PA could be demonstrated. In contrast, cyclic GMP is probably not involved in the control of PA. Calcium-depleted tissues had a low PA (approx. 40% below controls), and did not respond to exogenous prostaglandin E1. These results suggest that transmesenteric passage of albumin is at least partly controlled by cyclic AMP and intracellular Ca2+ levels.

Animals↗
PubMed1981

Cyclic AMP and permeability coefficient of albumin of the isolated rat mesentery. Effects of Escherichia coli endotoxin.

We have investigated the mechanisms whereby Escherichia coli endotoxin exerts its exudative effects, by using an isolated rat mesentery placed as a separation membrane between the two compartments of a diffusion cell. The permeability coefficient of albumin (PA) can be easily computed from the equilibration rate of 125I-labeled albumin added to one compartment. E. coli endotoxin increased PA in a concentration-related manner. Direct measurements revealed an early and transient increase in cyclic AMP and prostaglandin E-immunoreactive material. These effects of endotoxin could be inhibited by indomethacin. Calcium-depleted tissues have a low PA, even though cyclic AMP levels could still be increased by endotoxin. It incubations were prolonged beyond 90 min, PA remained elevated, but prostaglandin E and cyclic AMP levels fell to control values. Similar results were observed with trypsin-treated tissues. These results suggest that transmesenteric passage of albumin is increased in the presence of endotoxin. During the earlier part of the incubation (up to 90 min), the effects could be related to a local synthesis of prostaglandin E, and are controlled by cyclic AMP and intracellular calcium levels. During longer incubations (90-280 min) mesothelial exfoliation could occur, allowing free diffusion of albumin through the remaining interstitial tissue.

Animals↗
PubMed1985

Ultrastructural evidence for contacts between migrating L5222 rat leukemia cells and extracellular matrix components of the rat mesentery.

The nature of interactions between cells migrating through tissues and their structural surroundings are largely unknown. We have therefore examined the ultrastructural relationship between L5222 rat leukemia cells, moving through the loose connective tissue of the mesentery, and components of the extracellular matrix (ECM). Ultrathin tissue sections, fixed in the presence of ruthenium hexammine trichloride (RHT), revealed the following: Constitutents of fibrillar and nonfibrillar elements of the ECM are in contact with the plasma membrane of L5222 cells. Linear nonfibrillar ECM elements contact the plasma membrane at point-like sites, often associated with root-like structures present within the submembraneous microfilament mesh. Aggregates of ECM material are connected to patch-like cell membrane sites, associated with a condensed, plate-like part of the microfilament mesh. Point-like and patch-like contacts are more numerous at the anterior part of polarized migrating L5222 cells than on the posterior end. In round resting leukemia cells they are evenly distributed around the cell periphery. We suggest that the ECM-cell membrane contacts represent tissue adhesion sites. We therefore hypothesize that in migrating cells a coordinate interaction occurs between the contact sites and the continuous microfilament meshwork which results in a simultaneous backward movement of ECM-membrane contacts on the cell body and in a net forward movement of the whole cell. Since Dembo et al. (1981) present a similar mechanism for in vitro locomotion of granulocytes, we assume that blood cell locomotion in vivo and in vitro depends on similar molecular mechanisms: force generation by the cell, transmembraneous linkage between cytoskeletal and ECM elements, and membrane fluidity. The major difference in blood cell locomotion through a three-dimensional tissue or on a plane substratum would then be given by the distribution of contact sites, occurring around the cell periphery or limited to the ventral cell surface, respectively.

Animals↗
PubMedDate not supplied

CT findings of plexiform neurofibromatosis involving the ileum and its mesentery.

We present a case of plexiform neurofibromatosis involving the ileum and its mesentery. Computed tomography (CT) scans showed a cluster of small soft-tissue density nodules, which represented a cross-sectional image of the enlarged peripheral nerves and wall thickening of the distal ileum. Trapped fat tissue was demonstrated between these enlarged nerves. Histopathologic studies of the resected specimen correlated well with CT findings.

Adult↗
PubMed2004

Blunt trauma to the gastrointestinal tract and mesentery: is there a role for helical CT in the decision-making process?

The CT diagnosis of bowel and mesenteric injuries is difficult and warrants optimal technique and skilled interpretation. We retrospectively reviewed 36 consecutive patients with blunt traumatic injuries to the bowel and mesentery at our regional level I trauma center during the past 3 years. Physical examination, laboratory, Computed tomographic (CT), and intraoperative findings were compared. Surgically proven bowel injuries (13 cases) occurred in the duodenum (three cases), ileum (two cases), jejunum (two cases), colon (three cases), and stomach (three cases). CT findings considered specific of bowel rupture were observed in 5/13 patients including: extraluminal oral contrast or luminal content extravasation (four cases) and discontinuity of hollow viscus wall (one case). In the remaining 8/13 CT findings considered suggestive of bowel injury consisted of: pneumoperitoneum (six), gas bubbles close to the injured hollow viscus (three), thickened (>4-5mm) bowel wall (five), bowel wall hematoma (three), intraperitoneal fluid of unknown source (three). Mesenteric injury (23 cases) were surgically observed at the level of the mesenteric vessels (17 cases), legament of Treitz (two cases), gastro-duodenal artery (one case), transverse (one case) and sigmoid mesocolon (one case). CT finding considered specific of mesenteric laceration was active extravasation of contrast material from the mesenteric vessels (10 cases). CT findings suggestive of mesenteric injury (13 cases) consisted of: mesenteric hematoma (five) and/or high attenuation fluid collections, within the mesenteric root (eight) and folds (four). Helical CT is sensitive in the identification of bowel and mesenteric injury after blunt trauma providing a wide spectrum of findings. However, CT cannot be used as the sole indicator in cases with isolated thichened bowel wall, mesenteric hematoma, bowel hematoma, pneumoperitoneum or gas bubbles. Persistent, active extravasation of intravenous constrast medium from the mesenteric vessels, in isolation or associated with further injuries, requires immediate exploration and repair; disruption of bowel wall and extravasation of oral contrast are definite signs of bowel rupture. Close clinical observation, monitoring, and surgical expertise are mandatory for appropriate management.

Contrast Media↗