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PubMed1996

Antithrombotic effects of aspirin and LMWH in a laser-induced model of arterials and venous thrombosis.

Antiplatelet drug aspirin and anticoagulant low molecular weight heparin (LMWH) were compared as arterial and venous antithrombotic preparations in the rat experimental model of the laser induced thrombus formation. A method to induce microthrombi in small mesenteric vessel (15-25 microns) has been developed to investigate antithrombotic drugs and to study platelet reactions. Mesenteric injuries are induced in the vascular system of Wistar rats with an argon laser. The laser beam induced formation of the vessel wall injury with damage of endothelial cells. Thrombus was formed within seconds after laser injury and grew rapidly. The aggregate can be swept away by the flow and a new thrombus was formed again. This embolization began within the minute following the laser flash. Thrombus formation and embolization were repetitive phenoma. Aspirin (100 mg/kg) and LMWH (1 mg/kg) are approximately the same as to decrease the number of emboli detached from the thrombus and the duration of embolization; both in venules and in arterioles. This results suggest reflexion about the role of platelets in venous thrombosis induced by laser beam.

Administration, Cutaneous↗
PubMed1993

Preoperative evaluation of intraabdominal tumors in children: gradient-recalled echo vs spin-echo MR imaging.

OBJECTIVE: The purpose of this study was to compare gradient-recalled echo (GRE) with spin-echo (SE) MR imaging in the assessment of vessel patency and tumor margins in children with intraabdominal tumors. MATERIALS AND METHODS: Findings on GRE and SE images in 10 children with abdominal neoplasms were retrospectively evaluated and compared with pathologic findings or results of CT studies. RESULTS: Detection of tumor thrombus was 100% with GRE sequences and 75% with SE sequences. The SE sequences yielded two false-positive diagnoses of tumor thrombosis, whereas the GRE sequences yielded no false-positive or false-negative diagnoses. In patients with extrinsic compression of the inferior vena cava by tumor, GRE images were consistently better than SE images for confirming vessel patency. GRE images also were superior to SE images at showing flow in mesenteric vessels, renal arteries, and renal veins. However, GRE images displayed tumor margins less well than SE images did, and they were also more susceptible to ghosting artifacts. CONCLUSION: Our results suggest that the GRE sequence is a useful adjunct to SE sequences for evaluating vascular involvement in children with abdominal tumors.

Abdominal Neoplasms↗
PubMed1995

A comparison of the relative risk of vessel injury with conical versus pyramidal laparoscopic trocars in a rabbit model.

OBJECTIVE: Our purpose was to compare the relative risk of vessel injury after use of a 5 mm conical-tipped trocar, a 5 mm pyramidal-tipped trocar, and a 10 mm pyramidal-tipped trocar in a rabbit vessel model. STUDY DESIGN: Plastic templates were placed in front of and behind 108 mesenteric vessels in 11 anesthetized New Zealand White rabbits. Laparoscopic trocars were inserted through the templates and mesentery. The incidence of vessel injury was determined at distances from the vessels ranging from 0 to 5 mm. RESULTS: The 5 mm conical trocar resulted in a vessel injury rate of 88% at 0 mm from the vessel but 0% at 1 or 2 mm. The 5 mm pyramidal trocar resulted in 100%, 88%, and 62% injury rates of 0, 1, and 2 mm from the vessels, respectively. The 10 mm pyramidal trocar resulted in a 100% injury rate at 0, 1, 2, or 3 mm from the vessels and 80% and 40% at 4 mm and 5mm, respectively. CONCLUSION: The relative risk of vessel injury is significantly increased by the use of pyramidal-tipped trocars when compared with conical-tipped trocars, especially if larger diameter trocars are used.

Animals↗
PubMed2005

Pancreas head carcinoma: frequency of invasion to soft tissue adherent to the superior mesenteric artery.

Despite radical extension of surgical procedures, the cure rate of pancreatic head carcinoma patients still remains low. A cause of this concerns unsuccessful locoregional control, which may originate from a positive surgical margin near the superior mesenteric artery (SMA). However, no studies have examined invasion of pancreatic carcinoma around the SMA. En bloc resection of the head of the pancreas and the superior mesenteric vessels was performed on 6 patients who had pancreatic head carcinoma invading the superior mesenteric vein. The specimens were cut perpendicular to the SMA and consecutive serial sections were made. The slices were stained with hematoxylin and eosin or immunohistochemistry for cytokeratin 19 to easily detect carcinoma tissue under a microscope. Nodal metastasis around the SMAs was found in all of the cases. There were no characteristics of the arrangement of the metastatic nodes along the SMA. Lymphatic emboli were often observed close to the metastatic nodes. Neural invasions were detected around the tumors in every case and were continuously connected with the extrapancreatic nerve plexus. The nerve plexus covering the SMA were involved in 4 cases. Involvement was observed mainly behind the SMA, reaching as far as the left side of the SMA in 3 cases. The invasion extended further upwards along the right side of SMA for the celiac nerve plexus. The lymphatics and the nerve plexus in the area around the SMA were frequently involved by pancreatic head carcinoma. This involvement would have been left behind unless the SMA was resected.

Aged↗
PubMed1984

Augmented thromboxane generation by mesenteric arteries from pancreatectomized diabetic dogs is coincident with the vascular tone enhancement evoked by Na arachidonate and prostacyclin.

We studied the relationships between arachidonic acid (AA) metabolism and contractile responses to Na arachidonate (NaA) and the prostaglandins (PGs) in mesenteric arteries isolated from sham-operated and totally pancreatectomized dogs. PGE2 and PGF2 alpha produced a similar dose-dependent relaxation of mesenteric arteries from normal and diabetic dogs. On the contrary, NaA and prostacyclin (PGI2) enhanced the resting basal tone of arteries from pancreatectomized animals but depressed it in arteries from intact normal control or from sham-operated groups. Inhibitors of thromboxane A2 (TXA2) biosynthesis abolished in vitro the vasoconstricting effect of NaA and PGI2 in diabetics whereas inhibitors of PGI2 biosynthesis blocked the vasodilating influence of NaA in normal mesenteric vessels. Additionally, antagonists of cyclooxygenase activity prevented both the vasoconstricting and the vasodilating actions of NaA in normal and in diabetic arteries, respectively, as well as the PGI2 tone enhancement in vessels from diabetics. In arteries from pancreatectomized animals treated with insulin, PGI2 induced a biphasic (constriction and relaxation) effect of a magnitude between that of effects seen in normal controls or sham-operated and those in untreated diabetic animals. The basal radioconversion of exogenous [1-14C]AA, showed that mesenteric arteries from diabetic dogs generated more TXB2 than did vessels from intact normal control or sham-operated dogs. Moreover, in the presence of exogenous PGI2, the vascular production of TXB2 from AA in the diabetic group was significantly greater than that of preparations not exposed to PGI2. The % conversion of AA into PGI2 (assessed as 6-oxo-PGF1 alpha) was similar in normal controls, in sham-operated and in diabetic vessels. Insulin given in vivo abolished the greater basal conversion of AA into TBX2 by mesenteric arteries from diabetic dogs and significantly attenuated the enhanced prostacyclin-evoked generation of thromboxane. The present results strongly suggest that the abnormal constricting response evoked by NaA and PGI2 in mesenteric arteries from diabetic dogs could be related to the generation of TXA2 by vessel walls.

Animals↗
PubMed1992

Mechanisms of action of cicletanine in human and guinea pig resistance arteries.

Human subcutaneous (s.c.) arteries and guinea pig mesenteric vessels (internal diameter 150-570 microns) were isolated and mounted on a microvascular myograph. Cicletanine-induced relaxation curves were constructed after preconstriction with either depolarising potassium (KPSS) or norepinephrine (NE) and in the presence and absence of indomethacin, glibenclamide, or tetraethylammonium chloride (TEA). Using only guinea pig vessels, cicletanine relaxation curves were constructed with and without charybdotoxin. In human vessels, there was no significant difference between cicletanine-induced relaxation in vessels preconstricted with either NE or KPSS, and neither ATP-sensitive or Ca(2+)-activated K channels were involved. However, with indomethacin added, in human vessels the maximal response to cicletanine (30 microM) was reduced by 51% (p less than 0.05). In guinea pig mesenteric arteries, cicletanine (30 microM) produced a 95% relaxation of the NE-constricted vessel and only 30% relaxation of the KPSS-constricted vessel (p less than 0.001). There was no evidence for any involvement of the ATP-sensitive K channel or the eicosanoid system. The relaxation to cicletanine (less than 3 microM) in with TEA added was greatly reduced (p less than 0.001) and with charybdotoxin added the concentration response curve to cicletanine was shifted approximately 3 log units to the right (p less than 0.001), suggesting an involvement of Ca(2+)-activated K channels. The acute vasodilator action of cicletanine is complex, with multiple mechanisms of action, and the relative importance of these varies in different species or at least in different vascular beds.

Animals↗
PubMedDate not supplied

Evaluation of a vessel-sealing device for small intestinal resection and anastomosis in normal horses.

OBJECTIVES: To compare arterial bursting pressure after vessel closure using a vessel-sealing device (LigaSure Atlas Laparoscopic Sealer/Divider Instrument; Valleylab, Boulder, CO), a ligate-and-divide stapling device (LDS), and 2-0 polydioxanone suture. To evaluate the LigaSure Atlas as a method for ligation of the mesenteric vasculature during small intestinal resection in normal horses. STUDY DESIGN: Experimental study. ANIMALS: Part A: jejunal segments from 19 horses. Part B: 6 horses, aged 1 to 18 years, weighing 330 to 509 kg. METHODS: Part A: Jejunal segments with mesenteric vessels were collected from 19 horses. After closure by 1 of 3 methods (LigaSure Atlas, LDS, 2-0 polydioxanone) arteries were cannulated, and bursting pressure was measured by incrementally increasing intraluminal pressure until failure. Part B: Six horses had jejunal resection and anastomosis using a vessel-sealing device (LigaSure Atlas) to provide hemostasis of the mesenteric vasculature. Horses were monitored clinically for 4 weeks. RESULTS: Part A: Mean +/- SEM bursting pressure after 2-0 polydioxanone ligation (1,014.50 +/- 279.05 mm Hg) was significantly greater than mean bursting pressure after LigaSure (554.25 +/- 228.79 mm Hg), which was significantly greater than the mean bursting pressure after LDS (373.25 +/- 183.69). Part B: No major operative or postoperative hemorrhage occurred after application of the LigaSure Atlas for sealing and transecting mesenteric vasculature during small intestinal resection in normal horses. CONCLUSIONS: The LigaSure Atlas appears to be a safe method for hemostasis of the mesenteric vasculature during small intestinal resection in normal horses. CLINICAL RELEVANCE: Benefits of the LigaSure Atlas vessel-sealing device include reduced time required to provide hemostasis, acceptable arterial bursting pressure, no remaining foreign material, and no risk for ligature slippage. In our experience, use of the LigaSure Atlas during small intestinal resection and anastomosis in horses is safe for ligation of vessels less than or equal to 7-mm diameter.

Anastomosis, Surgical↗
PubMed2003

Successful treatment of mesenteric vasculitis caused by Henoch-Schönlein purpura with methylprednisolone pulse therapy.

Although mesenteric vasculitis due to Henoch-Schönlein purpura (HSP) is relatively uncommon, it is the most life-threatening manifestation associated with high mortality. We describe a 15-year-old boy with HSP who had massive gastrointestinal bleeding and ileus but delayed onset of the purpuric rash. Abdominal ultrasonography revealed thickening of both small and large intestinal walls, and CT found prominent mesenteric vessels with comb sign and double wall of the bowel. These findings were consistent with mesenteric vasculitis and bowel ischaemia. The ischaemic intestine recovered after methylprednisolone pulse therapy and surgical intervention was avoided. Our report suggests that corticosteroid pulse therapy may help controlling HSP with massive gastrointestinal haemorrhage and ischaemic bowel due to widespread mesenteric vasculitis.

Adolescent↗
PubMed2004

Reduced release of nitric oxide to shear stress in mesenteric arteries of aged rats.

We hypothesized that aging is characterized by a reduced release of nitric oxide (NO) in response to shear stress in resistance vessels. Mesenteric arterioles and arteries of young (6 mo) and aged (24 mo) male Fischer 344 rats were isolated and cannulated. Shear stress (15 dyn/cm(2))-induced dilation was significantly reduced and shear stress (1, 5, 10, and 15 dyn/cm(2))-induced increases in perfusate nitrite were significantly smaller at all shear stress levels in vessels of aged rats. Inhibition of NO synthesis abolished shear stress-induced release of nitrite. Furthermore, shear stress (15 dyn/cm(2))-induced release of nitrate was significantly higher and total nitrite (nitrite plus nitrate) was significantly lower in vessels of aged rats. Tiron or SOD significantly increased nitrite released from vessels of aged rats, but this was still significantly less than that in young rats. Superoxide production was increased and the activity of SOD was decreased in vessels of aged rats. There were no differences in endothelial NO synthase (eNOS) protein and basal activity or in Cu/Zn-SOD and Mn-SOD proteins in vessels of the two groups, but extracellular SOD was significantly reduced in vessels of aged rats. Maximal release of NO induced by shear stress plus ACh (10(-5) M) was comparable in the two groups, but phospho-eNOS in response to shear stress (15 dyn/cm(2)) was significantly reduced in vessels of aged rats. These data suggest that an increased production of superoxide, a reduced activity of SOD, and an impaired shear stress-induced activation of eNOS are the causes of the decreased shear stress-induced release of NO in vessels of aged rats.

Aging↗
PubMed2000

CT evaluation of mesenteric panniculitis: prevalence and associated diseases.

OBJECTIVE: This study was undertaken to assess the prevalence of mesenteric panniculitis on CT and to describe its appearance and associated diseases. SUBJECTS AND METHODS: A total of 7620 consecutive abdominal CT examinations were prospectively evaluated for features common to mesenteric panniculitis such as a well-delineated inhomogeneous hyperattenuated fatty mass at the mesenteric root, envelopment of mesenteric vessels, and no evidence of invasion of the adjacent small-bowel loops that may be displaced. RESULTS: CT findings of mesenteric panniculitis were seen in 49 patients (0.6%). We found a female predominance. Mesenteric panniculitis coexisted with malignancy in 34 patients and with benign disorders in 11 patients. In the remaining four patients, mesenteric panniculitis, verified on histology, was considered to be responsible for the patients' clinical manifestations; no other abnormality was identified. Soft-tissue nodules (n = 39) and a fatty halo surrounding vessels and nodules (n = 42) were observed in most patients. Follow-up abdominal CT examinations in 29 of the 49 patients showed changes in only one patient. CONCLUSION: CT findings of mesenteric panniculitis may be seen in patients undergoing abdominal CT for various symptoms.

Adolescent↗
PubMedDate not supplied

Anterior transposition of the third part of the duodenum in the management of chronic duodenal compression by the superior mesenteric artery.

Transposition of the third part of the duodenum anteriorly to the superior mesenteric vessels was performed in ten patients with chronic duodenal obstruction due to compression by the superior mesenteric artery (SMAS). Follow-up evaluation showed that all the patients (a) had complete relief of their preoperative symptoms, (b) could tolerate normal diet postoperatively and (c) gained weight rapidly following surgery. There were no major complications or deaths among the patients so treated. The Author feels that this technique is more direct approach, aimed at permanently circumventing the obstruction for these groups of patients selected on the basis of the radiological, pathological and operative findings. The success encountered with the patients so treated would seem to confirm this impression.

Adult↗
PubMed1994

Heterogeneity of vascular DNA synthesis in response to the development of Goldblatt two-kidney, one clip hypertension.

OBJECTIVE: To examine the changes in the rate of DNA synthesis in the aorta and mesenteric and subcutaneous resistance arteries during the development of renovascular hypertension. METHODS: Goldblatt two-kidney, one clip hypertensive and sham-operated control rats were studied 3, 7, 14 and 28 days after surgery. DNA synthesis was measured as the hourly rate of [3H]-thymidine incorporation into the DNA. RESULTS: Three days after renal artery constriction there was a significant increase in the DNA synthesis in both the aorta and the mesenteric vessels, although the blood pressure was not changed. DNA synthesis was elevated during the development of hypertension, but returned to control levels after 28 days when the blood pressure had reached a plateau. By contrast, there was no increase of DNA synthesis in the subcutaneous vessels at any time after renal artery constriction. The plasma renin concentration also was increased after 3 days in the clipped rats and remained elevated throughout the study. There were no significant changes in the blood pressure, the plasma renin concentration or the rate of vascular DNA synthesis in the sham-operated control rats. CONCLUSIONS: These data indicate that there are regional differences in the vascular response to the induction of renovascular hypertension and that in some vascular beds an increase in DNA synthesis precedes the rise in blood pressure.

Animals↗
PubMed2004

Quinapril effects on resistance artery structure and function in hypertension.

The effects of chronic treatment with quinapril on blood pressure, vascular reactivity and structure of resistance arteries were examined in adult, male spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. SHR and WKY at 15 weeks of age were treated with quinapril (10 mg/kg per day) for 10 weeks. Structural changes in the mesenteric arteries were measured by optical sectioning with confocal microscopy and in renal arteries by light microscopic measurements. Apoptotic cells in the mesenteric vessel wall were identified using the terminal deoxynucleotide transferase-mediated dUTP-nick end-labelling (TUNEL) method. The response of mesenteric arteries to noradrenaline, electrical stimulation, acetylcholine and sodium nitroprusside was studied using a pressure myograph system. Treatment with quinapril significantly lowered systolic blood pressure and ventricular weight in both SHR and WKY. It reduced wall thickness and medial volume in mesenteric arteries from SHR and WKY and media-to-lumen ratio in interlobular arteries of SHR. It also decreased the number of smooth muscle layers in SHR and increased the number of apoptotic smooth muscle cells in both SHR and WKY. In addition, treatment normalized the augmented contractile responses and improved the impaired relaxation response of SHR mesenteric arteries to the level of WKY. We conclude that treatment with quinapril lowered blood pressure and improved cardiac and vessel structure and vessel function. An increase in apoptotic process of medial smooth muscle cells is one of the mechanisms underlying the vascular structural improvement.

Animals↗
PubMed1975

Mesenteric baroreceptors.

Occlusion of the mesenteric vessels in the cat and injection of catecholamines produced significant changes in skin and muscle blood flows. These were abolished by cutting the mesenteric nerves. The occurrence of systemic pressure and peripheral resistance changes in cross-perfused mesenteric preparations indicates that hemodynamic factors alone, such as might result from occlusion of a large vascular region, were not initiating the reflex. This also excludes extramesenteric receptors within the heart and large vessels from the reflex. Since both intravascular pressure and catecholamines have been shown to modify Pacinian receptor discharge in vivo, the evidence suggests that the mesenteric Pacinian corpuscle is the baroreceptor probably initiating the vasomotor reflexes in skin and muscle. The net effect of mesenteric receptor activity appears to be an inhibition of vasomotor neurons supplying skin and muscle.

Animals↗
PubMed1998

Effects of 17beta-oestradiol on rat isolated coronary and mesenteric artery tone: involvement of nitric oxide.

Pre- and post-menopausal women receiving oestrogen replacement therapy have a significantly reduced risk of cardiovascular disorders. It has been suggested that this protection might be partly a result of a direct relaxant effect of oestrogens on coronary arteries. This study examines and directly compares the effects of 17beta-oestradiol on rat isolated coronary and mesenteric vessels. The influence of nitric oxide on these responses was also investigated. 17Beta-oestradiol caused similar concentration-dependent relaxation of isolated coronary and mesenteric resistance arteries pre-contracted with either KCl (60 mM) or 9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin (U46619; 1 microM). The relaxation responses to 17beta-oestradiol were significantly reduced, but not totally inhibited, in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase; they were not altered by indomethacin, an inhibitor of prostaglandin synthesis. The responses to 17beta-oestradiol in the presence of L-NAME were not dependent on the vessel studied or the pre-contracting agent used. These results suggest that nitric oxide might contribute to the vasodilatory effects of 17beta-oestradiol in rat isolated coronary and mesenteric resistance arteries.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2006

Changes in the function and ultrastructure of vessels in the rat model of multiple low dose streptozotocin-induced diabetes.

In this study we investigated functional changes in the femoral artery and ultrastructural alterations in mesenteric vessels and capillaries in the rat model of multiple low dose streptozotocin (STZ)-induced diabetes. Participation of oxidative stress in this model of diabetes was established by studying the effect of the pyridoindole antioxidant stobadine (STB) on diabetes-induced impairment. Experimental diabetes was induced by i.v. bolus of STZ (20 mg/kg) given for three consecutive days to male rats. At the 12(th) week following STZ administration, the animals revealed typical signs of diabetes, such as polyphagia, polydypsia and polyuria. There was no weight gain in the diabetic groups throughout the experiment. No exitus occurred in any group. Diabetes was characterised with high levels of plasma glucose, no significant changes in lipid metabolism, decreased serum levels of glutathione, increased serum levels of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAGA), injured endothelial relaxant capacity of the femoral artery and alterations in ultrastructure of mesenteric arteries and capillaries. Antioxidant STB in the dose of 25 mg/kg body weight i.p. (5 times per week) did not influence glucose levels, however, it mitigated biochemical, functional and ultrastructural changes induced by diabetes, suggesting a role of reactive oxygen species in diabetes-induced tissue damage.

Animals↗
PubMed2005

Influence of elastin on rat small artery mechanical properties.

We have previously developed a method for estimating elastin content and organization in resistance arteries, where it is a minor component. The aim of the present study was to validate the method against a quantitative assay and to determine the relative importance of elastin content and organization for intrinsic elasticity of small arteries. Mesenteric third order branches (from 10-day-old, 1- and 6-month-old rats) and middle cerebral arteries (from 6-month-old rats) were pressurized. beta-Values were calculated from stress-strain relationships and used as indicators of intrinsic stiffness. The same pressure-fixed arteries were used to estimate elastin content and organization in the internal elastic lamina with confocal microscopy. Collagen and elastin contents were determined by Picrosirius Red staining and radioimmunoassay for desmosine, respectively. Confocal and desmosine assays gave similar results: no difference in elastin content of mesenteric vessels from 1- and 6-month-old rats, and a significant reduction in cerebral compared to mesenteric arteries. For all parameters (elastin and collagen content, fenestrae area and internal elastic lamina thickness) the best correlation was found between beta-values and fenestrae size. These data suggest that in small arteries: (1) confocal microscopy can be used as a method for the simultaneous study of changes in elastin content and organization; and (2) elastin organization might be a key determinant of intrinsic elastic properties.

Aging↗