Portal Vein Wall Research Articles

Potential role of the neuropeptide CGRP in the induction of differentiation of rat hepatic portal vein wall

The media of the rat hepatic portal vein is composed of an internal circular muscular layer (CL) and an external longitudinal muscular layer (LL). These two perpendicular layers differentiate progressively from mesenchymal cells within the first month after birth. In this paper, we studied the development of calcitonin gene-related peptide (CGRP) innervation during post-natal differentiation of the vessel. We show that CGRP innervation is already present around the vessel at birth in the future adventitia but far from the lumen of the vessel. Progressively, CGRP immunoreactive fibers reached first LL then CL. CL by itself become only innervated at day 14 after birth. This corresponds to the time at which thick filaments (myosin) are visible in electron microscopy and desmin visualisable by immunocytochemistry. Furthermore, we provide evidence by autoradiography, that binding sites for CGRP are transiently expressed on the portal vein media at day 1 and 14 after birth. Vascular smooth muscle cells were transfected with constructs containing promoters for desmin or smooth muscle myosin heavy chain (smMHC). CGRP treatment of the cells significantly increased the expression of smMHC. Overall these results suggest that CGRP can potentially influence the differentiation of smooth muscle cells from the vessel wall.

Appropriateness of a Donor Liver with Respect to Macrosteatosis: Application of Artificial Neural Networks to US Images—Initial Experience

To retrospectively compare performance of artificial neural networks (ANNs) applied to ultrasonographic (US) images with that of radiologists for prediction of appropriateness of a donor liver with respect to macrosteatosis before liver transplantation. Institutional ethics committee approved study; written informed consent was obtained. ANNs, constructed with three-layered 15-neuron back-propagation algorithm, were trained to predict appropriateness of a donor liver with respect to macrosteatosis by using statistically significant laboratory and US parameters derived from univariate analyses, together with correct diagnosis. Input variables for ANNs were alkaline phosphatase, glutamic oxaloacetic transaminase, glutamic pyruvate transaminase, gamma-glutamyltransferase, hepatorenal ratio of echogenicity, and tail area ratio and tail length of portal vein wall echogenicity. Three radiologists graded US images in 94 potential donors (71 men and 23 women) on the basis of four degrees of hepatic steatosis. After training and testing of ANNs, performance of ANNs and radiologists in predicting appropriateness of potential donors was evaluated with receiver operating characteristic (ROC) analysis and compared by means of univariate z score test. Among 94 potential donor livers, 76 were normal or had mild steatosis, and 18 had moderate or severe macrosteatosis at histopathologic examination. Area under ROC curve (Az) of ANNs (Az=0.9673) was significantly greater than that of radiologists (faculty, Az=0.9106, P=.048; fellow, Az= 0.9038, P=.044; resident, Az=0.8931, P=.038). No statistically significant difference in sensitivity for predicting appropriateness as a liver donor with respect to macrosteatosis was found between ANNs (88.9%) and radiologists (P >.05). However, specificity of ANNs (96.1%) was significantly better than that of radiologists (P <.003). ANNs might be a useful tool to categorize whether a donor liver is appropriate for transplantation with respect to macrosteatosis on the basis of multiple variables related to laboratory and US features. Further study is needed.

Smooth muscle cells and interstitial cells of blood vessels

A rise in intracellular ionised calcium concentration ([Ca 2+] i) at sites adjacent to the contractile proteins is a primary signal for contraction in all types of muscles. Recent progress in the development of imaging techniques with special accent on the fluorescence confocal microscopy and new achievements in the synthesis of organelle- and ion-specific fluorochromes provide an experimental basis for study of the relationship between the structural organisation of the living smooth muscle myocyte and the features of calcium signalling at subcellular level. Applying fluorescent confocal microscopy and tight-seal recording of transmembrane ion currents to freshly isolated vascular myocytes we have demonstrated that: (1) Ca 2+ sparks originate from clustered opening of ryanodine receptors (RyRs) and build up a cell-wide increase in [Ca 2+] i upon myocyte excitation; (2) spontaneous Ca 2+ sparks occurred at the highest rate at certain preferred locations, frequent discharge sites (FDS), which are associated with a prominent portion of the sarcoplasmic reticulum (SR) located close to the cell membrane; (3) Ca 2+-dependent K + and Cl − channels sense the local changes in [Ca 2+] i during a calcium spark and thereby couple changes in [Ca 2+] i within a microdomain to changes in the membrane potential, thus affecting excitability of the cell; (4) an intercommunication between RyRs and inositol trisphosphate receptors (IP 3Rs) is one of the important determinants of intracellular calcium dynamics that, in turn, can modulate the cell membrane potential through differential targeting of calcium dependent membrane ion channels. Furthermore, using immunohystochemical approaches in combination with confocal imaging we identified non-contractile cells closely resembling interstitial cells (ICs) of Cajal (which are considered to be pacemaker cells in the gut) in the wall of portal vein and mesenteric artery. Using electron microscopy, tight-seal recording and fluorescence confocal imaging we obtained information on the morphology of ICs and their possible coupling to smooth muscle cells (SMCs), calcium signalling in ICs and their electrophysiological properties. The functions of these cells are not yet fully understood; in portal vein they may act as pacemakers driving the spontaneous activity of the muscle; in artery they may have other a yet unsuspected functions.

Objective criteria of triangular cord sign in biliary atresia on US scans.

To develop objective criteria for the ultrasonographic (US) appearance of the triangular cord (TC) sign for the diagnosis of biliary atresia. US was performed in 86 infants with jaundice. Biliary atresia (n = 20) was confirmed with hepatoportoenterostomy. Neonatal hepatitis (n = 66) was diagnosed with needle biopsy (n = 5), cholescintigraphy (n = 19), or clinical findings (n = 42). Thickness of the echogenic anterior wall of the right portal vein (EARPV) was measured. The TC sign was defined as thickness of the EARPV of more than 4 mm on a longitudinal scan. Biliary atresia was diagnosed when the TC sign was present. Statistical analyses were performed to compare the thickness of the EARPV between patients with biliary atresia and those with neonatal hepatitis and to test the significance of a 4-mm thickness as the criterion for the TC sign in the differentiation of biliary atresia from neonatal hepatitis (P <.05). The TC sign was present in 16 (80%) of 20 patients with biliary atresia and in one of 66 patients with neonatal hepatitis. Mean thickness of the EARPV was significantly greater in patients with biliary atresia (5.39 mm) than in patients with neonatal hepatitis (2.17 mm) (P <.05). Use of 4-mm thickness as the criterion for TC sign was statistically significant (P <.05), resulting in a sensitivity of 80%, specificity of 98%, and positive and negative predictive values of 94% for the diagnosis of biliary atresia. An objective criterion of the TC sign is an EARPV thicker than 4 mm on a longitudinal scan.

Portal hypertension in a dog due to circumscribed fibrosis of the wall of the extrahepatic portal vein

A two-and-a-half-year-old German shepherd dog with ascites and a high concentration of blood ammonia was investigated. Sonographically, its liver was normal but the portal vein was dilated and the flow...

Hilar cholangiocarcinoma involving the portal vein bifurcation: long-term results after resection.

Resection offers the only potential cure of hilar cholangiocarcinoma. Portal bifurcation involvement is often thought to contraindicate resection. We reviewed our experience with aggressive surgical management in 28 patients with hilar cholangiocarcinoma. All patients underwent hepatectomy and bile duct resection with hepaticojejunostomy. In 10 cases (group 1) the portal bifurcation was involved, necessitating portal resection and reconstruction; 18 (group 2) had no portal involvement. Frozen section of duct margins was routine. Survival was estimated using the Kaplan-Meier method and compared with the log-rank test. Portal reconstruction in group 1 was by graft interposition (1), venoplasty using the posterior wall of the right portal vein (2), or end-end anastomosis (7). Hepatectomies included right trisegmentectomy (8), right lobectomy (4), and left lobectomy (16); 20 (71%) had concomitant caudate resection. Median survival was 18 months in group 1 and 32 months in group 2 ( P, not significant [NS]). One-, 3-, and 5-year survivals were 60%, 22%, and 22%, respectively, in group 1 and 70%, 47%, and 38%, respectively, in group 2 ( P= 0.319). Portal involvement by hilar cholangiocarcinoma does not contraindicate resection.

Fine structure of the mouse portal vein in relation to its peristaltic movement.

The hepatic portal vein has been known to make a spontaneous peristaltic movement in some mammals, including the mouse and rat. To investigate the fine structure of the portal vein in relation to its physiological characteristics, we observed the mouse portal vein by using various histological techniques including conventional light microscopy, videomicroscopy, transmission and scanning electron microscopy, and real-time confocal laser scanning microscopy. The mouse hepatic portal vein was provided with a spiral fold which was produced by the inner layer, i.e. the endothelium and smooth muscles of the wall protruding into the lumen. Longitudinal smooth muscle cells spanned the interval of the fold, like a spirally arranged palisade around the vessel wall. The longitudinal muscle fibers ended at the spiral fold, being partly connected with a network of irregularly shaped smooth muscle cells. This network, hitherto unknown, was recognized to be restricted to the fold in distribution and characterized by numerous gap junctions connecting the muscle cells. Real-time confocal laser scanning microscopy using a Ca2+ sensitive fluorescent dye revealed that a transient and periodic increase in Ca2+ concentration occurred in the longitudinal smooth muscle cells and was transmitted spirally from the intestinal to the hepatic side. These findings indicate that, during the peristaltic movement, the contraction of smooth muscle cells is transmitted along the longitudinal smooth muscles of the portal vein wall toward the liver, presumably controlled by the network of the irregularly-shaped smooth muscle cells in the fold of the portal vein. Light microscopic observation in some specimens indicated an occurrence of cardiac muscle cells outside the smooth muscle layer. Restricted to the site of the porta hepatis in distribution, their involvement in the peristaltic contraction of the portal vein seemed unlikely.

The hepatologist in the haematologists' camp.

The hepatologist in the haematologists' camp.

Intravascular ultrasonography for assessment of portal vein invasion by pancreatic carcinoma.

Intravascular ultrasonography (IVUS) was performed to diagnose portal vein invasion by pancreatic carcinoma. In 55 patients with pancreatic carcinoma, the intravascular ultrasonographic catheter was introduced during operation through a branch of the superior mesenteric vein into the intrahepatic portal vein. The catheter was gradually withdrawn, and the cross-sectional images of the area under investigation were recorded. Altogether 45 patients underwent resection, and 34 underwent combined resection of the portal vein. The IVUS findings were compared with the histologic findings of the resected specimen, preoperative computed tomography (CT), and arterial portogram. The wall of the portal vein was visualized as an echogenic band with a thickness of 0.5 to 1.0 mm. A subtle portal vein invasion can be detected by observing this portal vein wall. For the diagnosis of portal vein invasion, the sensitivity, specificity, and overall accuracy of IVUS were 99.6%, 92.3%, and 94. 5%, respectively. The equivalent values for portography were 79.3%, 61.5%, and 70.9%; and those for CT were 82.1%, 74.1%, and 78.1%. IVUS provides more valuable and accurate information on portal vein invasion by pancreatic carcinoma than either CT or portography.

Clinical features of inflammatory liver disease in cats: 41 cases (1983–1993)

Objective To compare the clinical and clinicopathologic findings in and prognosis for cats with lymphocytic portal hepatitis (LPH) versus cats with acute or chronic cholangiohepatitis (CH). Design Retrospective study. Animals 25 cats with LPH; 16 cats with CH (7 acute, 9 chronic). Procedure Cats with LPH and CH were selected by evaluating records from liver biopsy specimens submitted to the University of Minnesota Veterinary Teaching Hospital during a 10-year period. Clinical and clinicopathologic data were retrieved. Results Cats with CH had higher segmented and band neutrophil counts, alanine aminotransferase activities, and total bilirubin concentrations than did cats with LPH. Cats with acute CH had higher segmented and band neutrophil counts and lower serum alkaline phosphatase activities and total bilirubin concentrations than did cats with chronic CH. Twelve of 14 cats with LPH or CH had coarse or nodular texture to the liver on ultrasonography, with loss of portal vein wall clarity noticed in 4 of 8 cats with LPH. Sixteen of 23 cats with LPH and 8 of 15 cats with CH survived &gt; 1 year. Of those cats living &lt; 1 year, all cats with LPH and 5 of 7 cats with CH had a serious concurrent illness that may have been responsible for their deaths. Clinical Implications LPH and CH can be detected and tentatively differentiated through evaluation of clinical laboratory test results, but histologic evaluation of liver specimens is necessary for definitive differentiation. Survival time was good regardless of the type of inflammatory liver disease. (J Am Vet Med Assoc 1999:214:513–516)

Transjugular Intrahepatic Portosystemic Shunt with PTFE-Covered Spiral Z-stent: An Experimental Study in Swine

Purpose : To improve TIPS patency by inserting polytetrafluoroethy l e n e ( P T F E ) - c ov-ered spiralZ-stents in swine. Materials and Methods : Using PTFE covered spiral Z-stents lined with TIPS tract from theportal vein wall to the inferior vena caval orifice of the right hepatic ve i n , TIPS were created in seven youngswine. The animals were followed up by portal ve n o g r a p hy and venous pressure was measured at two - weekintervals for 12 weeks or until shunt occlusion. After sacrifice, resected liver was examined grossly andpre-pared for histology. Results : The fifty percent patency rate using lifetime analysis was 83 % at 4 weeks, 33%at 6 weeks, 17 % at 8 weeks and 0% at 10 weeks. Venography demonstrated that the predominant sites of stenosiswere the portal vein wall(2/6), the TIPS tract(2/6) and the IVC orifice of the right hepatic vein(2/6). One swinedied 11 days after TIPS due to illness, and bile leaks were discovered in two of the seven animals. Histologicstudy demonstrated intimal hyperplasia in either the portal vein wall or the end of the stent at which the IVCorifice was located, as well as thrombus and pseudointimal hyper-plasia in the TIPS tract. Conclusion : P T F E -c overed spiral Z-stents were easily placed and significantly im-proved TIPS patency.

Intraportal endovascular ultrasonography for pancreatic cancer.

Intraportal endovascular ultrasonography (IPEUS) is a new diagnostic procedure for pancreatic cancer. In portal invasion, subtle invasion and compression are difficult to differentiate with conventional imaging techniques such as computed tomography and angiography. IPEUS is performed with an 8-French, 20-MHz intravascular ultrasound catheter. IPEUS provides high-resolution, real-time images perpendicular to the portal vein axis. With IPEUS, the portal vein wall is visualized as an echogenic band. A subtle portal invasion can be detected by observing this portal vein wall. Moreover, the segment II of the extrapancreatic nerve plexus is visualized as an echogenic area around the inferior pancreaticoduodenal artery (IPDA). The extrapancreatic nerve plexus invasion can be diagnosed as low echoic infiltration of the area around the IPDA. In the diagnosis of portal vein and extrapancreatic nerve plexus invasion, IPEUS provides a good diagnostic value and important information for the staging of local extension of the pancreatic cancer.

Echogenicity of hepatic versus portal vein walls revisited with histologic correlation.

The portal vein wall typically is hyperechoic over a wide range of beam-vessel angles, whereas the hepatic vein wall is hyperechoic only when the incident beam and the vessel are perpendicular. This has been attributed to marked discrepancies in mural thickness, collagen content, or perivascular fat between portal and hepatic veins. We evaluated histologically the walls of portal and hepatic veins using three cadaveric livers. For vessels with luminal diameter above 2 to 3 mm, hepatic vein and portal vein wall thicknesses were similar such that portal vein walls were not more than 50% thicker than those of hepatic veins of comparable size. Hepatic vein walls were mostly composed of parallel, tightly packed collagen fibers. In contrast, portal vein walls were composed of loosely arrayed, nonparallel connective tissue fibers which were separated by multiple intervening spaces and only a minority of which were collagenous. Perivascular fat was not identified adjacent to intrahepatic vessels beyond the liver hilus. The marked differences in echogenicity between portal vein and hepatic vein walls typically observed at ultrasonography thus cannot be attributed to differences in mural thickness, collagen content, or perivascular fat between these vessels. Rather, the distinct composition of the hepatic vein wall renders it a specular reflector, which is hyperechoic only when the angle between the ultrasound beam and the vessel wall is close to 90 degrees, whereas the composition of the portal vein wall enables it to appear hyperechoic at a wide range of beam-vessel angles.

Transjugular intrahepatic portosystemic shunt with silicone-covered Wallstents: results in a swine model.

To evaluate the use of impermeable silicone-covered Wallstents for transjugular intrahepatic portosystemic shunt creation. A transjugular intrahepatic portosystemic shunt was created in 14 young swine (weight, 20-32 kg) by using impermeable silicone-covered Wallstents. In eight animals, the silicone covering extended from the portal vein to the inferior vena cava. In two swine, the silicone covering ended short of the inferior vena cava, in two it ended short of the portal vein wall, and in two it ended short at each end. Follow-up transhepatic portal venography was performed weekly for 6 weeks or until the shunt was occluded. Animals were then sacrificed for gross and histologic evaluation. Only two of 14 shunts were patent after 3 weeks; both were stenosed with luminal narrowing of more than 50% in the middle of the shunt. By 6 weeks, all shunts were occluded. At histologic evaluation, a marked foreign-body reaction with superimposed thrombosis was demonstrated. In comparison with uncovered Wallstents, impermeable silicone-covered Wallstents are associated with decreased patency at transjugular intrahepatic portosystemic shunt creation. This is likely due to increased thrombogenicity and a foreign-body reaction.

Contrast-Enhanced Endoscopic Ultrasonography with Galactose Microparticles: SHU508 A (Levovist)

To evaluate the utility of a suspension of galactose microparticles available as SHU508 A (Levovist) as a contrast agent during endoscopic ultrasonography (EUS). Three sets of experiments were performed on three 20-25 kg swine (Sus scrofa) under general anesthesia. Upper EUS was performed with an echo endoscope with color Doppler capability (Pentax FG-32 UA). The celiac artery, superior mesenteric artery, aorta, portal vein, pancreas, and gastrointestinal wall were imaged by EUS. Multiple intravenous bolus injections of 400 mg/ml of SHU508 A were made, and their effect on color Doppler and gray-scale imaging during EUS was studied. After contrast injection there was a significant, visually noticeable enhancement of the color Doppler signals from the celiac artery, superior mesenteric artery, and portal vein. Vessels with weak to no color Doppler signals before injection of SHU508 A--for example, the celiac artery and superior mesenteric artery--were observed to have strong color signals after injection. The effect of SHU508 A on color Doppler imaging was easily appreciated subjectively without the need for complex quantitative measurements. No visually noticeable color Doppler enhancement was seen in vessels such as the aorta that had a very pronounced color Doppler signal even prior to the injection of contrast. Movement of particulate matter was seen in the portal vein on the gray scale. Intravenous SHU508 A as a contrast agent significantly enhances color Doppler signals during EUS. Vascualar contrast of this sort could potentially have a significant role in improving the accuracy of EUS in diagnosing malignant vascular invasion, the detection of occult pancreatic neoplasms, and the diagnosis of vascular thrombosis.

Lymph node metastasis in carcinoma of the body and tail of the pancreas.

There have been no precise reports concerning lymph node metastatic involvement in carcinoma of the body and tail of the pancreas. Histopathological examination of lymph node involvement in 30 specimens obtained from patients who underwent pancreatic resection and wide dissection of lymph nodes, including para-aortic lymph nodes, for carcinoma of the body and tail of the pancreas was performed. Fourteen of 30 patients had lymph node involvement. The highest incidence of lymph node involvement was around the splenic artery (five of 30 patients), aorta (four of 30) and coeliac trunk (four of 30). No significant difference in survival rate between the lymph node-negative group and the lymph node-positive group was observed, but all patients in the positive group died within 2 years after surgery, and four patients with para-aortic lymph node involvement died from recurrence within 10 months after surgery. Survival rates were significantly worse in patients with histopathological extrapancreatic nerve plexus invasion, retropancreatic tissue invasion, tumour diameter more than 4 cm, histological portal system vein wall invasion and carcinoma invasion of the surgical margins. Although aggressive extended surgery including para-aortic node dissection has been performed, the postoperative survival rate is still low in patients with carcinoma of the body and tail of the pancreas. The high incidence of liver metastasis after surgery is a prime cause of the poor outcome, and effective therapy for postoperative liver recurrence requires evaluation.

Clinical significance of carcinoma invasion of the extrapancreatic nerve plexus in pancreatic cancer.

To elucidate the clinical significance of neural invasion in pancreatic carcinoma, a clinicopathological study was performed. Neural invasion is a common feature of pancreatic carcinoma whose clinical significance has not yet been determined. Over a period of > 10 years, 129 of 204 (63%) patients with pancreatic carcinoma underwent resection by extensive radical surgery. A clinicopathological study of those specimens of pancreatic carcinoma was performed, with particular reference to neural invasion. Intrapancreatic neural invasion was observed in 116 of 129 (90%), of which 80 (69%) showed extrapancreatic nerve plexus involvement. A statistically significant (p < 0.001) correlation between the grade of intrapancreatic neural invasion and extrapancreatic nerve plexus invasion was observed. The postoperative survival rate for patients with extrapancreatic nerve plexus involvement was significantly (p < 0.001) lower than that for patients without extrapancreatic nerve plexus involvement. Patients who survived for > 3 years after operation had no extrapancreatic nerve plexus invasion even when portal vein wall invasion was observed.

Intraportal Endovascular Ultrasonography in the Diagnosis of Portal Vein Invasion by Pancreatobiliary Carcinoma

The purpose of this study was to determine the value of intraportal endovascular ultrasonography (IPEUS) in the diagnosis of portal vein invasion by pancreatobiliary carcinoma. The authors reported their experiences with this new technique and compared it with conventional imaging technologies, such as portography and computed tomography (CT). Pancreatobiliary carcinoma often invades the portal vein. Observation of the echogenic band of the portal vein wall by means of a high-frequency, high-resolution intravascular ultrasound catheter allows for the accurate diagnosis of the portal vein invasion. A prospective study of 30 consecutive patients with pancreatobiliary carcinoma (16 pancreatic carcinomas, 8 bile duct carcinomas and 6 gallbladder carcinomas) was performed. In 23 cases IPEUS was performed intraoperatively from the superior mesenteric venous route with an 8 French, 20 MHz intravascular ultrasound catheter. In 7 cases IPEUS was performed before surgery from the percutaneous transhepatic route with a 6 French, 20 MHz intravascular ultrasound catheter. The finding of IPEUS was confirmed by pathologic examination of resected specimens and surgical exploration. The results of IPEUS were compared to those of portography and CT. Intraportal endovascular ultrasonography visualized the portal vein wall as an echogenic band with a thickness of 0.5 mm to 1.0 mm. The diagnostic criterion of portal vein invasion was destruction of this echogenic band. Portal vein invasion was found in 15 of 30 cases. Vascular invasion was confirmed by pathologic examination of resected specimens in 10 patients and operative findings in 5. The sensitivity, specificity, and overall accuracy of IPEUS for diagnosis of portal vein invasion was 100%, 93.3%, and 96.7%, respectively. The values were 80%, 67.7%, and 73.3% for portography and 53.3%, 80%, and 66.7%, respectively, for CT. Intraportal endovascular ultrasonography provided precise information about the relationship between the pancreatobiliary tumor and the portal vein wall. It was capable of accurately detecting or excluding early invasion of the portal vein wall by pancreatobiliary carcinoma.

Subpressor angiotensin II is a bifunctional growth factor of vascular muscle in rats.

The proposition that angiotensin II in subpressor does stimulates vascular growth in vivo was tested. Young adult, male Sprague-Dawley rats received angiotensin II, 200 ng/kg per min intraperitoneally by osmotic minipump, for 24 h or 7-10 days. Sham-infused rats served as controls. Protein (35S-methionine) synthesis in aortic media, portal vein, bladder wall and diaphragm; proteoglycan (35S-sulfate) synthesis in aorta and bladder and synthesis of DNA (3H-thymidine) in aortic media were all measured ex vivo in the rat. The systolic blood pressure of angiotensin II-treated rats was unchanged at 24 h and increased at 7-10 days. At 24 h in angiotensin II-treated rats the protein synthesis in aortic media, portal vein and bladder wall but not in the diaphragm was increased, indicating that the hypertrophic effect of angiotensin II was independent of the arterial pressure. The rate of 35S-methionine washout from angiotensin II- and sham-treated aorta was the same. At 24 h there was also an increase in proteoglycans synthesis of the aorta and bladder wall of angiotensin II-treated rats. In contrast to protein synthesis, the incorporation of 3H-thymidine into aortic muscle DNA was reduced in angiotensin II-treated rats at 24 h, suggesting the inhibition of DNA synthesis. At 7-10 days angiotensin II administration the protein synthesis of aortic media returned to baseline, and DNA synthesis was bimodal: in 53% of rats (n = 10) inhibition continued, and in 26% (n = 5) it was increased by two- to threefold. The present findings confirm in vivo the bifunctionality of the trophic vascular action of angiotensin II. Vascular hypertrophy may play a role in the slow pressor action of angiotensin II.

The characterization of pancreatic and bile duct tumours by duplex Doppler

Duplex Doppler imaging was used to study the effect of pancreatic and bile duct tumours on portal vein and hepatic artery blood flow and the specific Doppler signals recorded from these tumours. Chaotic portal vein flow occurred in 35% (14) of pancreatic and 20% (6) of biliary tumours and complete portal vein occlusion in 28% (11) and 10% (3) respectively. Twenty-eight per cent (11) of pancreatic and 7% (2) of bile duct tumours had high frequency shift Doppler signals and 22% (9) of pancreatic tumours had a signal indicating low impedence flow. Both signal types are suggestive of malignancy. The results suggest that pulsed Doppler imaging has a valuable place in the ultrasound assessment of portal vein wall invasion, is an important staging criterion for pancreatic and biliary tumours and may assist in differentiating benign from malignant lesions.