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At least 307 records · Page 17Linked to original sources
PubMed1987

Effect of albumin on the osmotic pressure exerted by myoglobin across capillary walls in frog mesentery.

1. Individual capillaries in mesenteries of pithed frogs were perfused sequentially with two frog Ringer solutions containing myoglobin at a concentration of 70 mg/ml. The first perfusate solution contained bovine serum albumin at a concentration of 10 mg/ml. The second perfusate contained no albumin. The modified Landis micro-occlusion technique (Michel, Mason, Curry & Tooke, 1974) was used to measure the capillary hydraulic conductivity and the effective osmotic pressure of the myoglobin solution across the capillary wall under conditions where the transcapillary concentration difference was established by steady-state ultrafiltration. 2. In six capillaries the effective osmotic pressure of the myoglobin solution at 20-22 degrees C was 15.9 +/- 2.2 (S.E. of mean) cmH2O when albumin was in the perfusate and 10.1 +/- 1.1 cmH2O after albumin was removed from the perfusate. 3. The hydraulic conductivity of the capillary wall increased from a mean value of 6.5 +/- 1.4 X 10(-7) cm/(s cmH2O) when albumin was in the perfusate to 15.6 +/- 3.8 X 10(-7) cm/(s cmH2O) during perfusion with Ringer solution containing myoglobin alone. 4. Control experiments to measure steady-state filtration rates at pressures 10-30 cmH2O were carried out to check the assumption in the method that the reduction in the measured osmotic pressure of myoglobin was the result of changes in the properties of the molecular sieve within the capillary wall and was not simply the result of solute accumulation on the tissue side of the capillary wall. 5. The measured reduction in the effective osmotic pressure of myoglobin when albumin was removed from the perfusate does not conform to the hypothesis (Crone, 1984) that the tight segment of the intercellular junction is the principal molecular filter for myoglobin in the wall of frog mesenteric capillaries. 6. Our results do conform to the hypothesis that a network of fibrous molecules, reinforced by adsorbed albumin, forms the principal molecular filter at the capillary wall in frog mesenteric capillaries.

Albumins↗
PubMed1961

Action of vasopressin on the permeability of mesentery.

Contemporaneous movements of Rb86 cations and of P(32) orthophosphate across isolated rabbit mesentery display kinetic patterns that are generally associated with passive diffusion. Vasopressin at a concentration of 100 milliunit/ml produced a significant increase in the permeability constant for P(32) and at the same time a significant decrease in the permeability to Rb(86). At lower hormone concentrations (0.1 milliunit/ml) the P32 response was less marked but still significant (P < .01), while the Rb(86) effect was not (P > .05). Hyaluronidase did not mimic these actions of vasopressin.

Animals↗
PubMed1992

Neoplastic and inflammatory processes of the peritoneum, omentum, and mesentery: diagnosis with CT.

Disease processes in the peritoneum, omentum, and mesentery occasionally are not recognized at radiologic examination. The authors have used computed tomography (CT) to categorize the radiologic appearances of the more common abnormalities into three basic patterns: (a) solid but relatively well-defined masses, (b) cystic-appearing masses, and (c) ill-defined or infiltrative processes. The most common solid masses to affect these anatomic regions are secondary neoplasms, which are associated with enhancement of the peritoneum on contrast material-enhanced CT scans and, typically, ascites. The various cystic-appearing masses (including cystic lymphangioma, cystic mesothelioma, teratoma, and loculated ascites) and infiltrating masses (such as peritoneal mesothelioma, retractile mesenteritis, desmoid, and carcinoid) must be differentiated on the basis of clinical findings and additional imaging findings (eg, CT depiction of fat and calcium in teratomas and the radiating appearance of carcinoids). Although the CT appearances of some of the abnormalities overlap, classifying them by pattern is helpful in narrowing the range of the differential diagnosis.

Humans↗
PubMedDate not supplied

Root of the small-bowel mesentery: correlative anatomy and CT features of pathologic conditions.

The root of the small-bowel mesentery (SBM) is an important peritoneal fold that is contiguous to other peritoneal ligaments and mesocolons. Several pathologic conditions can occur in the SBM itself, and diseases that spread through the connections from adjacent organs frequently involve it. The root of the SBM is contiguous to the hepatoduodenal ligament around the superior mesenteric vein (SMV) and contiguous to the right side of the transverse mesocolon around the gastrocolic trunk. The inferior mesenteric vein, which is a landmark of the descending mesocolon, runs along the left side of the root of the SBM. Malignant neoplasms can spread to the SBM by means of direct extension, extension along the neural plexus, extension along neighboring ligaments, or extension along lymphatic vessels. Inflammatory conditions such as pancreatitis and perforation of a jejunal diverticulum can also spread to the SBM. Anomalies that can occur in the SBM include rotation anomalies and internal hernia. Vascular lesions of the SBM include thrombosis of the superior mesenteric artery (SMA), acute SMV thrombosis, SMA dissection, arterioportal fistula, and portal venous gas. Other pathologic conditions that can occur in the SBM are edema or congestion, mesenteric tear, mesenteric panniculitis, and tumors or tumorlike lesions.

Humans↗
PubMed1980

Appearance of lymphomatous involvement of the mesentery by ultrasonography and body computed tomography: the "sandwich sign".

A characteristic appearance of lymphomatous involvement of the mesentery is demonstrated by ultrasonography and computed tomography. The presence of a lobulated confluent mass infiltrating the mesenteric leaves and encasing the superior mesenteric artery and veins producing a "sandwich-like" appearance is reported in seven patients with Hodgkin and non-Hodgkin lymphoma. Retroperitoneal adenopathy was present in all seven patients. In six, a correct prospective diagnosis was made and a major revision of therapeutic planning occurred. Laparotomy was deferred in three patients. The anatomy, pathophysiology, and clinical importance are detailed.

Adult↗
PubMed1987

Normal anatomy and pathologic changes of the small bowel mesentery: US appearance.

The ultrasonographic (US) appearance of the normal small bowel mesenteric leaves was evaluated in two in vitro studies and in 30 patients. Such structures had an elongated shape, echogenic surfaces, and small vessels in their center and could be recognized in 28 of the 30 patients. They did not show active movements, and at their distal end, the small bowel loops could be seen and peristalsis detected. Doppler signals were obtained from the small vascular structures in their center in three additional cases. On the basis of these anatomic findings, pathologic changes such as lymphoma, desmoid tumor, metastatic lesions, dilated vessels, and edema could be detected in 15 patients. When examining with US patients with diseases prone to involve the mesentery, careful attention should be given to this structure, since useful information about the abdominal spread of the disease can be obtained.

Adult↗
PubMed1996

Effects of bradykinin on lymphatic pumping in rat mesentery.

The effects of bradykinin on lymphatic pump activity of rat mesenteric collecting duct were studied, and the receptor subtype responsible for the bradykinin response was evaluated. Rats were anesthetized with intraperitoneal alpha-chloralose and urethan, and exteriorized mesenteries were studied using intravital microscopic techniques. The diameter of the collecting lymph vessels (approximately 100 microns) was continuously monitored and lymphatic pump parameters (end diastolic diameter, end systolic diameter, stroke volume index, ejection fraction, contraction frequency, and pump flow index) were calculated. Bradykinin (0.1-1.0 nM) did not affect end diastolic diameter, end systolic diameter, stroke volume index, and ejection fraction. Bradykinin increased lymphatic contraction frequency and pump flow index in a dose-dependent manner. Des-Arg9-[Leu8]bradykinin (B1 antagonist, 0.1 microM) had no effect on baseline lymphatic pumping but completely inhibited the bradykinin-induced increase in contraction frequency. N-acetyl-D-Arg-[Hyp3,Thi5,8,D-Phe7] bradykinin (B2 antagonist, 0.1 microM) significantly depressed lymphatic contraction frequency in baseline conditions but had no effect on bradykinin-induced increases in contraction frequency. These results indicate that bradykinin induces positive chronotropic but not inotropic effects on lymphatic pump activity through the stimulation of B1 receptors.

Adrenergic beta-Antagonists↗
PubMed2003

Microlymphatic and tissue oxygen tension in the rat mesentery.

Oxygen phosphorescence quenching was used to measure tissue Po(2) of lymphatic vessels of 43.6 +/- 23.1 microm (mean +/- SD) diameter in tissue locations of the rat mesentery classified according to anatomic location. Lymph and adipose tissue Po(2) were 20.6 +/- 9.1 and 34.1 +/- 7.8 mmHg, respectively, with the difference being statistically significant. Rare microlymphatic vessels in connective tissue not surrounded by microvessels had a Po(2) of 0.8 +/- 0.2 mmHg, whereas the surrounding tissue Po(2) was 3.0 +/- 3.2 mmHg, with both values being significantly lower than those of adipose tissue. Lower of lymph fluid Po(2) relative to the surrounding tissue was also evident in paired measurements of Po(2) in the lymphatic vessels and perilymphatic adipose tissue, which was significantly lower than the Po(2) in paired adipose tissue. The Po(2) of the lymphatic fluid of the mesenteric microlymphatics is consistently lower than that of the surrounding adipose tissue by approximately 11 mmHg; therefore, lymph fluid has the lowest Po(2) of this tissue. The disparity between lymph and tissue Po(2) is attributed to the microlymphatic vessel wall and lymphocyte oxygen consumption.

Adipose Tissue↗
PubMed2001

Nitric oxide decreases pacemaker activity in lymphatic vessels of guinea pig mesentery.

Intracellular microelectrode recordings were used to determine whether nitric oxide (NO), affects the pacemaker events that initiate vasomotion in lymphatic vessels of the guinea pig mesentery. This pacemaker activity is recorded as spontaneous transient depolarizations (STDs) and is likely to arise through synchronized Ca2+ release from intracellular stores. We show here that acetylcholine-induced endothelium-derived NO and exogenous NO released by sodium nitroprusside (SNP; 100 microM) and DEA-NONOate (500 microM) reduced the frequency and amplitude of STDs. This inhibition of STD frequency and amplitude was independent of the NO-induced hyperpolarization of the smooth muscle. The SNP-induced inhibition of STD frequency and amplitude was abolished during superfusion with the soluble guanylyl cyclase inhibitor ODQ (10 microM) and was diminished in the presence of cGMP and cAMP-dependent protein kinase inhibitors. The data are consistent with the hypothesis that NO inhibits vasomotion primarily by production of cGMP and activation of both cGMP- and cAMP-dependent protein kinases, which reduce the size and frequency of STDs, probably by acting on the underlying synchronized Ca2+ release from intracellular stores.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Suggestive evidence for a microanatomical relationship between mast cells and nerve fibres containing substance P, calcitonin gene related peptide, vasoactive intestinal polypeptide, and somatostatin in the rat mesentery.

A close microanatomical relationship between serotonin-positive mast cells and nerve fibres positive for substance P, calcitonin gene related peptide, vasoactive intestinal polypeptide, and somatostatin has been observed in whole-mount preparations of rat mesentery by an immunofluorescent double-staining procedure. Peptidergic fibres have been shown either to run in close proximity or come in direct contact with mast cells. This supports earlier morphological and immunohistochemical results suggesting an innervation of mast cells and provides a structural foundation for a series of pharmacological studies which outline the influence of various neuropeptides on mast cell secretory activity.

Animals↗
PubMed1983

Ultrastructure of normal rabbit mesentery.

The ultrastructure of the mesentery was examined by electron microscope (EM) after in vivo fixation in 7 normal rabbits. In 1, the fixation was performed after intravenous injection of an electron-dense tracer (iron dextran) and intraperitoneal infusion of dialysate 4.25% for 1 h. We studied morphometric data of what is considered to be the active peritoneal dialysis membrane, i.e. capillary endothelial cells, interstitium and mesothelial cells. The mesothelial cells are flattened and overlapping with tight junctions between them. They lie on a continuous basement membrane and they contain numerous intracytoplasmic vesicles, separated or in clusters. The mesenteric microvessels were mainly true capillaries of continuous type and postcapillary venules. Capillary lymphatics and larger lymphatic channels (lacunae) seem to be more extensive than the blood capillaries and venules. The endothelial cells contain many vesicles. The interstitium consists of bundles of collagen, fibroblasts and occasional macrophages. The electron-dense tracer was found in the vesicles of the mesothelial cells suggesting that vesicular transport may play an important part in the transportation of at least molecules of a certain size.

Animals↗
PubMed1978

The distribution of blood rheological parameters in the microvasculature of cat mesentery.

In vivo studies of the rheological behavior of blood in the microcirculation were conducted by direct in situ measurements in cat mesentery. Upstream to downstream pressure drops were measured in unbranched arterioles, capillaries, and venules, with diameters from 7 to 58 micrometer. Simultaneous measurements of red cell velocity and vessel geometry facilitated computation of bulk velocity, pressure gradient, apparent viscosity, wall shear stress, and resistance. Arteriovenous distributions of these parameters revealed the following. Maximum pressure gradient (0.015 cm H20/micrometer) occurs in the true capillaries (7 micrometer in diameter); intravascular wall shear stress averaged 47.1 dynes/cm2 in arterioles and 29.0 dynes/cm2 in venules. Extreme values as great as 200 dynes/cm2 were observed in a few shunting arterioles. Apparent viscosity averaged 3.59 cP in arterioles, 5.15 cP in venules, and 4.22 cP overall. Intravascular resistance per unit length of microvessel varied with luminal diameter as a power law function with exponents of -4.04 for arterioles, -3.94 for venules, and -3.99 for all vessels combined. This apparent maintenance of Poiseuille's law is attributed to the opposing processes of hematocrit reduction and decreasing shear rate as blood is dispersed in successive arteriolar segments, and the converse action of these processes in the venous confluences which lessen the extent of network variations in apparent viscosity. Reductions in bulk velocity from the normal flow state to below 0.5 mm/sec resulted in increases in apparent viscosity by a factor of 2 to 10, which are attributed primarily to obstruction of the lumen by leukocyte-endothelium adhesion.

Animals↗
PubMed2001

Calcifying fibrous pseudotumor of mesentery presenting with acute peritonitis: case report with immunohistochemical study and review of literature.

Calcifying fibrous pseudotumor (CFP) is a benign soft tissue lesion composed of thick collagen bundles, scattered fibroblasts, and psammomatous and dystrophic calcifications, located most commonly in the extremities and trunk of children and young adults. The present case in a 36-year-old woman is to the best of our knowledge the first report of a large CFP confined to the mesentery, which, because of torsion, led to acute peritonitis and emergency laparotomy. The typical histologic features were accompanied by a prominent myofibroblastic proliferation along with inflammatory response at the periphery of the lesion. The spindle cells of the lesion were positive for vimentin and focally for CD34 and smooth-muscle actin. Review of the literature and discussion of differential diagnosis in this report focuses on abdominal CFP and other intraabdominal soft tissue lesions, some of which may be precursors of CFP. Int J Surg Pathol 9(3):249-253, 2001

Acute Disease↗
PubMed1978

The misplaced caecum and the root of the mesentery.

Five cases presenting in late infancy and childhood with symptoms and signs referable to malrotation of the midgut are described. The condition may present with jaundice, malabsorption or the signs and symptoms of intestinal obstruction due to internal hernia or volvulus. It may also result in volvulus and gangrene of the midgut. A short root of the mesentery predisposing to this event will be seen on a barium meal and follow through examination and will warn of its impending occurrence.

Cecum↗
PubMed1996

Case report: identification of the transverse mesocolon and root of small bowel mesentery; a new sign of pneumoperitoneum.

A new sign of pneumoperitoneum was observed in a patient with perforation of the ascending colon. The presence of free air in the peritoneal cavity allowed identification of the transverse mesocolon and the root of the small bowel mesentery on plain abdominal radiographs obtained in the supine and in the prone position. This sign may be an aid in the diagnosis of pneumoperitoneum.

Aged↗
PubMed1992

Malignant lymphoma in the mesentery with immune thrombocytopenia.

A 69-year-old man was referred to our hospital for further evaluation of an abdominal mass. After admission, he was suspected of having a malignant mesenteric tumor. Laboratory data disclosed thrombocytopenia with increased levels of platelet-associated immunoglobulin G. On surgery, the tumor involved the ileal mesentery, invading the urinary bladder and mucosal surface of the terminal ileum. The diagnosis of mesenteric lymphoma with immune thrombocytopenia was made. Complete remission was obtained after surgery and the subsequent three courses of combination chemotherapy. However, thrombocytopenia still persisted. This rare presentation is discussed with a review of the available literature.

Aged↗
PubMed1978

Detection of neoplastic involvement of the mesentery and omentum by computed tomography.

A total of 39 patients undergoing abdominal computed tomography and subsequent surgical biopsy of the mesentery or omentum were studied to evaluate the sensitivity of CT in detecting metastases to those areas. Twelve patients had negative biopsies; there were no false positive CT interpretations in that group. Of the 27 patients with positive biopsies, 18 showed positive findings on CT scan. Those patterns of involvement are described and illustrated. The nine false negative cases related to very small metastatic foci, contiguity with the primary tumor, or paucity of intraabdominal fat.

Abdominal Neoplasms↗