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PubMed1998

Cytochemical evidence for potassium-dependent p-nitrophenylphosphatase activity in pavement cells of Rana esculenta mesentery.

BACKGROUND: We previously reported that during hibernation in Rana esculenta, various organs (i.e., skin, urinary bladder, kidney) change their osmoregulatory activity. Here, we considered the possible role of the frog mesentery in the ion transport, evaluating morphological and cytochemical (K+-p-nitrophenylphosphatase activity) aspects. METHODS: Pieces of mesentery from Rana esculenta collected in their natural environment during April, June, October, and January were processed to reveal ultrastructural morphology and K+-p-NPPase activity, using cerium as capture agent. RESULTS: The mesenteric mesothelium contained three types of cells: pavement, mitochondria-rich, and ciliated. Only the pavement cells expressed intense reactivity on the basolateral membranes and in the adjacent pinocytotic vesicles; some reaction product also was found on the apical membranes. Moreover, morphological and cytochemical characteristics of the pavement cells appeared to be very seasonal. CONCLUSIONS: The presence of mitochondria-rich cells and ciliated cells, generally found in structures involved in the transport of liquids, as well as K+-p-NPPase activity and pinocytosis in pavement cells, is consistent with the hypothesis that frog mesentery may be involved in seasonally variable osmoregulation.

4-Nitrophenylphosphatase↗
PubMed1998

Primary leiomyosarcoma of the jejunal mesentery: report of a case.

The occurrence of a primary leiomyosarcoma of the mesentery is rare. A 61-year-old man was admitted to the hospital complaining of an abdominal mass. The findings of both abdominal ultrasonography and a computed tomography (CT) scan revealed an irregular and heterogeneous mass located in the mesentery. A laparotomy was performed and a 7.0 x 6.5 cm tumor was thus found within the jejunal mesentery. The tumor was successfully resected by a combined resection of 40 cm of the jejunum and end-to-end anastomosis of the jejunum. Pathological examination of the resected specimen revealed leiomyosarcoma. The patient had an uneventful postoperative course, but multiple liver metastases were discovered 1 year and 5 months after the initial operation. A second operation was performed, but the patient died due to hepatic failure and unexpected bleeding from the cut surface of the remnant liver. Preoperative imaging examinations, including abdominal ultrasonography and CT scan, were thus found to be useful tools for both identifying and diagnosing the origin and extension of a mesenteric mass. However, even using such diagnostic techniques an accurate diagnosis of intraabdominal leiomyosarcoma remains difficult.

Humans↗
PubMed1986

Mast-cell-mediated angiogenesis: a novel experimental model using the rat mesentery.

The angiogenic effect of autogenous secreting mast cells (MCs) was studied using a novel experimental approach. The virtually avascular membranous rat mesentery was used as test tissue. The activation of MCs was elicited by repeated intraperitoneal injections of the MC-secretagogue compound 48/80, which per se appears inert from the proliferogenic and angiogenic point of view. Angiogenesis was quantitated histologically and expressed the number of vessels/unit length of mesentery. The smallest vessels recognized had a luminal area of approximately 7-8 microns 2 (corresponding to a circular diameter of 3.0-3.2 microns). Seven to ten days after MC-activation ended, the number of blood vessels had increased 7- to 6-fold. A retrogressive reaction occurred between days 21 and 38 after treatment, when the number of vessels had essentially normalized, as compared to vehicle-treated controls. The present study, introducing the membranous mesentery as a model for quantitative angiogenetic studies, provides evidence that MCs can induce angiogenesis, which is new. The possible therapeutic implication of this finding is noteworthy.

Animals↗
PubMed2005

Inflammatory pseudotumor of the sigmoid colon mesentery: US and CT findings (2004:12b).

The concept of inflammatory pseudotumor has evolved from meticulous pathological studies; some of its histological features resemble a spindle-cell sarcoma. Despite the fact that it usually affects children and young adults, only limited numbers of childhood cases have been reported in the pediatric literature. Recognition of this rare entity is important because the clinical manifestations and radiological features may be indistinguishable from a malignant lymphoproliferative disorder. This entity has been reported to be anywhere in the body, including a variety of intra-abdominal organs. Although one of the most common intra-abdominal sites is the mesentery, localization within the mesentery of the sigmoid colon is particularly rare. We present a case of abdominal inflammatory pseudotumor of the sigmoid colon mesentery, defining its radiological and primarily ultrasound and Doppler ultrasound findings, with a review of additional examples from the literature.

Child↗
PubMed2002

Diffuse mesenterial sclerosis: a characteristic feature of chronic small-bowel allograft rejection.

Chronic rejection is the major cause of late intestinal allograft dysfunction. The aim of this study was to analyze in detail the histopathological features of chronic rejection in the ACI-to-Lewis rat model of intestinal transplantation. Chronic rejection was achieved in orthotopic small-bowel allografts (ACI-Lewis) by limited immunosuppression with cyclosporin A (CyA). Isogeneic transplants (ACI-ACI) as well as native bowels (ACI) with and without immunosuppression served as controls. Bowels were removed together with the mesenteries 90 days postoperatively and analyzed using sections stained with hematoxylin and eosin as well as Masson's trichrome. The slides were coded, randomized and analyzed by grading of histological abnormalities. The most striking alterations of the allografts were noticed in the mesenteries exhibiting an extensive infiltration by mononuclear cells accompanied by a progressive diffuse fibrosis with shrinking of the mesenteries. These changes were most pronounced in the perivascular areas of the mesenteric arteriae and venae rectae. Three of five allografts showed vasculitis with myointimal proliferation of the arteriae rectae. Focally, there was spill-over of the inflammatory cells onto the intestinal muscularis propria. The mucosa of the allografts showed mild blunting, lymphocytic infiltration of the crypt epithelium and increased crypt cell apoptoses. The submucosa was unaffected, and there were no detectable abnormalities of the enteric ganglion cells. The present data support the view that chronic rejection of intestinal allografts is characterized by a diffuse sclerosing mesenteritis which may significantly contribute to late graft dysfunction. The present model may be useful to study the pathomechanisms of this inflammatory fibrosing process.

Animals↗
PubMed2000

A chylous cyst of the mesentery: report of a case.

A case is presented of an adult chylous cyst of the mesentery that was preoperatively diagnosed to be a pancreatic cystadenoma. A 66-year-old asymptomatic male was followed up for 15 months under the diagnosis of a benign pancreatic cyst. On October 1997, computed tomography showed a 45 x 40 mm cystic mass in the upper abdomen which came in contact with the pancreas. Endoscopic ultrasonography revealed a multilocular mass with a 7 x 4 mm elevated lesion. Endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography revealed the cystic mass to be unrelated to the pancreatic duct. The preoperative diagnosis was a pancreatic cystadenoma or cystadenocarcinoma. A laparotomy showed a 50 x 40 mm cystic mass containing chylous fluid, that arose from the mesentery of the upper part of the jejunum. The pathological diagnosis was a chylous cyst of the mesentery. The preoperative diagnosis in this case was very difficult because the chylous cyst appeared to be attached to the pancreas and this phenomenon is considered to be extremely rare.

Aged↗
PubMed2005

Mesenteritis precedes vasculitis in the rat mesentery after subacute administration of a phosphodiesterase type 4 inhibitor.

Inhibitors of phosphodiesterase type 4 (PDE4) are currently exploited as potent drugs for pulmonary diseases. Some PDE4 inhibitors induce necrotizing panarteritis in the mesentery of rats, comparable to spontaneous polyarteritis nodosa in rats and vascular alterations that are induced by various vasoactive compounds, such as fenoldopam and inhibitors of PDE3. The mechanism of toxicity is unknown. In order to investigate the development of arteritis in the splanchnic vasculature of rats, a time-course study was performed with high doses of a compound (BYK169171), specifically inhibiting PDE4. Rats were treated orally for 1-28 days, and alterations in the mesentery were evaluated by histology, morphometry, and immunohistology. As early as 3 days after the onset of treatment, a mesenteritis was found, characterized by macrophage infiltration, fibroblast proliferation, neovascularization, and loss of adipocytes. Incidence and severity of the mesenteritis were low during the first 2 weeks of treatment, but increased with duration of treatment, finally affecting 2/3 of all animals. A segmental necrotizing panarteritis was detected in some rats treated for 21 or 28 days, but always followed a mesenteritis, whereas many animals with mesenteric inflammation did not have vascular lesions. We postulate that PDE4 inhibitors do not cause a primary vasculitis/arteritis in rats, but induce a non-purulent inflammation as the predominant initial toxic effect in the mesentery. This renders their toxic effect distinct from that of PDE3 inhibitors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

An approach for studies of mediator-induced leukocyte rolling in the undisturbed microcirculation of the rat mesentery.

1. Although intravital microscopy is the method of choice for observation of inflammatory leukocyte rolling and adhesion in small venules in vivo, a problem with this technique is that surgical exposure of suitable tissues per se triggers the rolling mechanism. In this study, we describe an approach to investigate induction of rolling in undisturbed microvessels. For this purpose, intravital microscopic observation of leukocyte rolling and adhesion in the rat mesentery was combined with histological determination of the intravascular concentrations of polymorphonuclear and mononuclear leukocytes (PMNL and MNL). 2. By relating the histologically determined number of intravascular leukocytes to either microvessel volume or to the erythrocyte concentration, the baseline MNL and PMNL content was found to be 3-6 fold higher in venules than in systemic blood. This increase in microvessel leukocyte concentration did not seem to be related to leukocyte-endothelium interactions, because the leukocyte concentration was similarly elevated in arterioles where rolling and adhesion did not take place. 3. Preparation of the rat mesentery for intravital microscopy time-dependently increased the venular PMNL concentration to over 100 fold the systemic PMNL concentration 45 min after exteriorization of the small intestine. The MNLs were much less responsive to the preparative manipulation. By treatment with the polysaccharide fucoidin (inhibits rolling but not firm adhesion per se), or by use of intravital microscopy immediately before tissue fixation, approximately 90% of the accumulated venular PMNLs were found to represent rolling cells. 4. Intraperitoneal injection of 10(-3) M histamine increased the venular PMNL (but not the MNL) concentration to almost 50 fold the systemic PMNL value. The histamine response did not vary with venular diameter, and the relative contribution of rolling vs firmly adherent cells to the PMNL, accumulation was again approximately 90%. Intraperitoneal injection of leukotriene C4, but not prostaglandin E2, caused a significant increase in venular PMNL concentration. 5. Systemic treatment with the anti-P-selectin monoclonal antibody PB1.3 had no effect on the histamine-induced venular PMNL accumulation (i.e. rolling) in female Wistar or male Sprague-Dawley rats. On the other hand, identical treatment with PB1.3 very effectively inhibited the histamine-induced PMNL response in the mesentery of rabbits. 6. In conclusion, we have shown that a histologically determined increase in leukocyte concentration in rat mesenteric venules may be used as an index of mediator-induced leukocyte rolling if the relative contribution of rolling and firm leukocyte adhesion is first determined, for example by the means described in this study. This relatively simple approach may be very useful for studying various aspects of leukocyte rolling when the 'spontaneous' rolling triggered by preparation of tissues for intravital microscopy is undesirable.

Animals↗
PubMed1994

Primary yolk sac tumors of the mesentery. A report of two cases.

Two yolk sac tumors that arose in the mesentery of the jejunum and the mesentery of the transverse colon of two male patients, aged 2 and 17 years, are reported. Both patients had abdominal masses. The tumors measured 9 and 11 cm in maximum dimension. One of them grew into the bowel lumen. Microscopically, both neoplasms exhibited several of the typical patterns of yolk sac tumor and stained immunohistochemically for alpha-fetoprotein. Both patients received chemotherapy postoperatively and are alive, but follow-up is short. The subject of extragonadal yolk sac tumors is reviewed, and histogenetic implications of their occasional origin in the mesentery is discussed.

Adolescent↗
PubMed1999

Gastrointestinal stromal tumors/smooth muscle tumors (GISTs) primary in the omentum and mesentery: clinicopathologic and immunohistochemical study of 26 cases.

Gastrointestinal stromal tumor or smooth muscle tumor (GIST) is the designation for a major subset of gastrointestinal mesenchymal tumors that histologically, immunohistochemically, and genetically differ from typical leiomyomas, leiomyosarcomas, and schwannomas. Because GISTs, like the interstitial cells of Cajal, the gastrointestinal pacemaker cells, express CD117 (c-kit protein), the origin of GISTs from the interstitial cells of Cajal has been recently proposed. Comparison of GISTs primary in the omentum and mesentery to GISTs primary in the tubular gastrointestinal tract is of particular diagnostic and histogenetic interest in view of the possible similarity of these tumors with the GIST group. In this study, we analyzed 14 omental and 12 mesenteric primary mesenchymal tumors representing smooth muscle tumors or GISTs. These tumors were phenotypically compared with gastric and small intestinal GISTs, leiomyomas of the esophagus, and leiomyosarcomas of the retroperitoneum. Most (13 of 14) omental and mesenteric (10 of 12) tumors showed histologic features similar to GISTs with elongated spindle cells or epithelioid cells with high cellularity; most of these tumors showed low mitotic activity. Omental and mesenteric GISTs were typically positive for CD117 and less consistently for CD34. They often showed alpha-smooth muscle actin reactivity but were virtually negative for desmin and S-100 protein. One omental and two mesenteric tumors showed features of leiomyosarcoma with ovoid, less elongated nuclei, cytoplasmic eosinophilia; all these tumors had significant mitotic activity. These tumors were positive for alpha-smooth muscle actin and two of them for desmin, but all were negative for CD34 and CD117, similar to retroperitoneal leiomyosarcomas. Tumor-related mortality occurred in the group of mesenteric GISTs, but not in the group of omental GISTs. In contrast, all three patients with a true leiomyosarcoma of the omentum or mesentery had documented liver metastases or died of tumor. In summary, we show that tumors phenotypically identical with GISTs occur as primary tumors in the omentum and mesentery. The occurrence of CD117-positive tumors outside the gastrointestinal tract militates against an origin of these tumors exclusively from the interstitial cells of Cajal.

Adult↗
PubMed2006

Leukocyte-endothelium interactions after hemorrhagic shock/reperfusion and cecal ligation/puncture: an intravital microscopic study in rat mesentery.

Hemorrhagic shock/reperfusion (HS/R) followed by sepsis triggers systemic microcirculatory disturbances that may induce multiple organ failure. The present study evaluated the effects of HS/R and cecal ligation and puncture, followed by necrotic cecal resection/peritoneal lavage (REL) on leukocyte-endothelium interactions at the mesentery. Eighty-one anesthetized Wistar rats (200-250 g) were randomly assigned to a first injury: (1) control-HS-no hemorrhagic shock/no reperfusion group, (2) HS/blood-HS/R with 25% shed blood, and (3) HS/blood + LR-HS/R with 25% of the shed blood + lactated Ringer's solution, 3x shed blood volume. Twenty-four hours post-HS/R, animals were submitted to cecal ligation and puncture and, 24 h thereafter, to REL. Leukocyte-endothelium interactions were assessed by intravital microscopy and intercellular adhesion molecule (ICAM) 1 and P-selectin expression by immunohistochemistry. Lungs were observed for ICAM-1 expression and neutrophil infiltration. Single and double injury induced significant increases in rolling (approximately 2-fold), adherent (approximately 5-fold), and migrated leukocytes (approximately 7-fold); ICAM-1 expression (approximately 1/2-fold), and P-selectin expression (approximately 1/2-fold) at the mesentery compared with control-HS group. REL normalized leukocyte-endothelium interactions at the mesentery in single-injured animals. However, in double-injured rats, adherence and migration of leukocytes decreased but did not normalize. Similar results were observed on ICAM-1 expression and neutrophil infiltration in the lungs from these animals. In conclusion, the current in vivo observation of the mesenteric microcirculation after a double injury followed by REL is a suitable model for the systematic evaluation of the inflammatory reaction at local and distant sites. In addition, data presented herein emphasized the importance of surgical removal of the septic focus in controlling the otherwise lethal sepsis-induced multiple organ dysfunction syndrome.

Animals↗
PubMed1988

Mesenterial-window hyperplasia in the lactating rat.

By examining the true mesentery adjacent to the small gut before and after weaning, as well as in age-matched controls, we found that the number of mesenteric windows, their total area, and their total DNA content increased significantly during lactation. Simultaneously, Feulgen-DNA absorption analysis in individual mesenteric cells showed that these had a normal DNA stemline, and a normal distribution within the G1-G2 range. The hyperplasia and growth developed and declined temporally somewhat parallel in the mesenterial windows and their adjacent small gut, suggesting that an as yet unknown common factor(s) governs the hyperplastic growth in both these tissues. The novel physiological, mesenterial-window hyperplasia in the lactating rat described in the present study may prove useful for studies of the mesenteric function and the regulation of cell proliferation.

Animals↗
PubMed1973

Splanchnic slowly adapting mechanoreceptors with punctate receptive fields in the mesentery and gastrointestinal tract of the cat.

1. A class of slowly adapting mechanoreceptors with A-delta and C fibres running in the splanchnic nerves of cats is described.2. The mechanoreceptors have punctate regions of mechanical sensitivity at macroscopic vascular branching points and have been found in the lesser omentum, the mesentery of the gall-bladder, porta hepatis, portal vein, pancreas, spleen and the duodenum, jejunum, ileum, colon and their mesenteries.3. The receptive fields of these mechanoreceptors vary considerably in size in the different regions. The largest receptive fields were found in the small intestinal mesentery and consisted of up to seven points of mechanical sensitivity at vascular divisions, each separated by distances of a few up to about 40 mm. The smallest receptive fields were single or double points of mechanical sensitivity which were most commonly found in relation to the portal vein in the root of the mesentery.4. Maintained stretch of the receptive field elicited a train of impulses which had phasic and tonic components. The tonic discharge was sometimes maintained for more than 1 min.5. Distension of a neighbouring viscus often caused a discharge which had a phasic component and a variable tonic component. The occurrence of the latter appeared to depend on the relative positions of the bowel and mesentery, and was probably associated with a change in tension on the mesentery.6. Occlusion of the portal vein resulted in some units in a discharge which began soon after the start of the occlusion.7. The receptors do not appear to be affected by acid, hypoxia or hypercapnia.

Action Potentials↗
PubMed1978

Microvascular pressures and filtration coefficients in the cat mesentery.

1. Filtration coefficient and hydrostatic pressure have been measured in single capillaries and venules in the cat mesentery using a modification of the Landis (1927) single vessel occlusion technique. 2. Venules were found to be filtering fluid, not absorbing it as is often supposed. 3. The mean filtration coefficient in capillaries was 0.018 micrometers . s-1 . mmHg-1 (1.35 X 10(-10)m . s-1 . Pa-1) while that in venules, was 0.027 micrometers . s-1 . mmHg-1 (2.02 X 10(-10)m . s-1 . Pa-1). 4. In both capillaries and venules, filtration coefficient increased with decreasing pressure. 5. The difference between directly measured venular pressure and that calculated from the occlusion data was used to determine the contribution of the interstitium to fluid exchange. In the mesentery superfused with Krebs solution the tissue pressure so determined was found to be zero or subatmospheric initially but became increasingly positive with lengthening exposure of the mesentery.

Animals↗
PubMed2003

Effects of in vivo lipopolysaccharide infusion on vasoconstrictor function of rat isolated mesentery, kidney, and aorta.

Continuous infusion of lipopolysaccharide (LPS) into conscious rats elicits regionally selective cardiovascular disturbances. The aim of the present study was to assess contractile function in different vascular preparations (renal, mesenteric, and thoracic aorta) taken from rats infused with LPS for 2 or 24 h. Sustained responses to continuous infusion of methoxamine but not to KCl were reduced in the aorta (at 2 and 24 h LPS) and mesentery (at 24 h LPS) but not in the renal vascular bed. In contrast, transient responses to bolus doses of methoxamine were unchanged in the mesentery. In Ca2+-imaging experiments with fura-2, challenge with a single concentration of methoxamine (10 microM, which showed an impaired contractile response at 24 h LPS) induced a rise in intracellular Ca2+ in the mesenteric artery that was not different from the control. Furthermore, in the aorta, the contractile response to caffeine was attenuated only in the 2 h LPS group. These results show that there is regional heterogeneity in in vitro vascular responsiveness in preparations taken from LPS-infused rats. Thus, in mesenteric beds and aortae, but not renal beds, there is hypocontractility to methoxamine that is not due to a generalized inability of the smooth muscle to contract, which is evident with sustained but not transient application of agonist (mesentery) and which, in late endotoxemia (24 h LPS), does not appear to involve abnormalities in Ca2+ mobilization or entry.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

Physiological roles of endogenous nitric oxide in lymphatic pump activity of rat mesentery in vivo.

Physiological roles of endogenous nitric oxide (NO) in the lymphatic pump activity of rat mesenteries in vivo were evaluated using an intravital video microscope system. Changes in the pumping frequency (F), the end diastolic diameter (EDD), and the end systolic diameter (ESD) of the mesenteric lymph microvessels were measured with the microscope system and then the pump flow index (PFI) was calculated. A 15-min superfusion of 30 microM N(omega)-nitro-L-arginine methyl ester (L-NAME) in the mesenteries caused significant increases of F and PFI and a significant decrease of the EDD and ESD. Simultaneous superfusion of 1 mM L-arginine with 30 microM L-NAME produced a significant reversal of the L-NAME-mediated increase of F and decrease of ESD. A 15-min superfusion of 100 microM aminoguanidine caused no significant effects on F, EDD, and ESD of the mesenteric lymph vessels in vivo. These findings suggest that endogenous NO has physiologically modulated the lymphatic pump activity in rat mesentery in vivo and that the production and release of NO may be mediated by constitutive NO synthase but not by inducible NO synthase.

Animals↗
PubMed1998

Mechanisms of cell injury in rat mesentery and cremaster muscle.

The events responsible for cell injury after a tissue stimulation are only incompletely understood. The purpose of this study was to examine mechanisms of cell injury in two tissues, rat mesentery and cremaster muscle, after tissue stimulation with N-formylmethionyl-leucyl-phenylalanine (FMLP) and platelet-activating factor (PAF). The response was studied in the same animal in random order using normal and leukopenic rats. The tissues were exteriorized after pentobarbital anesthesia. Five to six vascularized areas were chosen in each tissue, and cell injury and hydroperoxide production were assessed visually by continuous superfusion with 1 microM propidium iodide and 5 microM dichlorofluorescin diacetate (DCFH), respectively. FMLP (1 x 10(-8) M) and then PAF (1 x 10(-8) M) were added to the superfusate, and measurements were made at several time points. The second tissue was then examined using the same protocol. In the cremaster, there was little hydroperoxide production, and the tissue injury was eliminated after leukopenia. Leukopenia had no effect on tissue injury in the mesentery. Although hydroperoxide production was observed, there was no correlation between it and the tissue injury. The level of preactivation showed no correlation with either tissue injury or hydroperoxide production. In light of these results, mast cell degranulation may be an important mechanism of tissue injury in the mesentery.

Abdomen↗
PubMed1997

Stapler division of the omentum and small bowel mesentery in morbidly obese patients undergoing gastric bypass surgery.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) procedures can be technically demanding because of anatomical factors including fat distribution, organ fixation, and wound depth. We developed a technique using the Multifire Endo GIA 60 2.5 disposable surgical stapler which allows greater mobilization, less blood loss, and decreased operating time. METHODS: A disposable stapler designed for laparoscopic surgery was used to transect the gastro-colic omentum and small bowel mesentery in 67 morbidly obese patients undergoing RYGB. Generally, five to six stapler cartridges were needed for the transections. RESULTS: Stapler division of the gastro-colic omentum and small bowel mesentery decreased operating time by an average of 25 minutes. CONCLUSIONS: Applying principles of laparoscopic surgery to RYGB resulted in more efficient mobilization of the stomach and the small bowel mesentery, as well as decreased blood loss and operating time.

Anastomosis, Roux-en-Y↗