Efferent Veins Research Articles

Lobular distribution pattern of lactate dehydrogenase and 6-phosphogluconate dehydrogenase activity in rat liver

Lactate dehydrogenase (LDH) and 6-phosphogluconate dehydrogenase (6-PGDH) activities were measured in lobular areas expanding between 3 portal tracts and an efferent central vein in the livers of male Wistar rats, using a Lowry technique. The maximum of LDH activity was found in a nearly uniform broad area in the lobular periphery. From that area values decreased along periportal/septal-->perivenous gradients, but only slightly within that area along the periportal-->septal axis of the vascular septum. Maximum values of 6-PGDH activity were present in an intermediate area close to the central vein demonstrating a rather inhomogeneous distribution pattern without a clear definition of zonal limits. Our data on the distribution pattern of LDH are in agreement with the concept of the metabolic lobulus and are supported by a recent evaluation of the vascular architecture in rat liver. The lobular distribution pattern of 6-PGDH cannot be interpreted without doubt in accordance with that concept.

Three-dimensional observations of spatial arrangement of hepatic zonation and vein system in mice and house musk shrews.

The three-dimensional (3D) relationship among the hepatic domains and the efferent central and afferent portal veins was investigated by macroscopy, microscopy, and computer-aided 3D reconstruction methods. To clearly distinguish the pericentral domain from the periportal, we used CCl(4)-treated mice and diabetic house musk shrews, which show typical pericentral necrosis and deposition of fat, respectively. The 3D findings obtained were verified against normal control animals using advantages of our unique observations by light and fluorescent microscopy, which made it possible to differentiate the two domains well. The pericentral domains in the mice and shrews appeared three-dimensionally as continuous branched columns, and the periportal domains exist in a sponge-like network that fills the parenchymal space among the columnar pericentral domains. The efferent central veins were concentrically surrounded by the pericentral domain, and segments of the central veins flowed into large sublobular and lobar veins. The walls of these large veins faced the pericentral domain at the confluence with the central veins; the remaining portions of the walls faced the periportal domain. The afferent portal veins were placed at the two-dimensional center of the network of the periportal domain and gave off smaller portal branches radially at the intersections of the network. Three types of liver lobules-classic, portal, and acinar-have been discussed repeatedly at the (2D) level. At the 3D level, it is reasonable to consider that the liver parenchyma consists of the two continuous domains corresponding to the distribution of the vessels that we found.

Expression pattern of glutamine synthetase marks transition from collecting into conducting hepatic veins.

The expression of glutamine synthetase (GS) is confined to a rim of hepatocytes surrounding the efferent hepatic veins in all mammalian species investigated. In rat liver, a two- to three-cell thick layer of GS-positive (GS(+)) hepatocytes uniformly surrounds the two to four terminal branching generations of the hepatic vein that collect blood from sinusoids (central veins). With increasing diameter of the efferent vessel, this multilayered rim of GS(+) hepatocytes becomes confined to patches surrounding the decreasing number of central vein outlets. The remaining part of the wall of these sublobar hepatic veins is bordered by a one-cell thick layer of GS(+) hepatocytes. Around still larger veins, this single-cell layer of GS(+) hepatocytes gradually disappears. The expression pattern of GS is therefore a convenient biological parameter to delimit sinusoidal draining ("collecting") from nondraining ("conducting") surfaces in the wall of the efferent hepatic vessels. The hepatocytes surrounding a single tree of central veins together form a compound liver lobule. (J Histochem Cytochem 47:1507-1511, 1999)

A New Animal Model to Study Intimal Hyperplasia in Arteriovenous Fistulas

Background. Intimal hyperplasia (IH) plays a key role in the failure of arteriovenous (AV) fistulas. The animal models available to study IH in AV fistulas are expensive and do not mimic the development of truly stenotic IH. In this study we examined whether goats are a more suitable model to study IH in AV fistulas.Materials and Methods. Thirteen direct and four bridge graft AV fistulas between the carotid artery and the jugular vein of goats were explanted 10 to 195 days after creation. Immunohistochemical staining and morphometric measurements of intima and media were performed in the artery, the vein, the toe, and the heel of the venous anastomosis. Ratios of intimal to medial thickness (Ith/Mth) and area (Ia/Ma) were calculated.Results. IH developed in all goats, mainly at the anastomosis (Ia/Ma = 0.17) and the efferent vein (Ia/Ma = 0.31). The artery was almost free of lesions (Ia/Ma = 0.03). In the efferent vein, Ith/Mth varied between 0.59 and 0.68. In the anastomosis the largest value of Ith/Mth was measured at the suture lines (0.88 and 0.91). Absolute intimal area increased with time. IH contained many vascular smooth muscle cells with a patchy display of desmin positivity, an abundance of smooth muscle cell α-actin positivity, and almost complete endothelial cell coverage. Occlusion was due to thrombus formation on the IH.Conclusion. A clear intimal hyperplasia developed in AV fistulas in goats at locations comparable to those in humans. Therefore, the AV fistula model in the goat may be seen as an effective model to study IH in hemodialysis AV fistulas.

Aneurysmal bone cyst: its pathogenesis based on angiographic, immunohistochemical and electron microscopic studies.

Based on angiographic, immunohistochemical as well as electron microscopic findings, authors outline a hypothesis for the etiopathogenesis of aneurysmal bone cysts. No changes were found at the arterial site in 16 studied aneurysmal bone cysts, with no signs of an arteriovenous shunt. In certain cases, however, dilated and tortous efferent veins became visible in the late venous phase. Due to the impedance of venous flow, the intracystic pressure increases and the small veins become dilated causing formation of aneurysmal slits. This is supported by the immunohistochemical finding that S-actin shows concentric arrangement around the aneurysmal cavities. Endothelial lining and basal membrane remnants were detectable in places, though the aneurysmal slits were devoid of continuous endothelial lining and basal membrane. We suggested that the aneurysmal bone cyst corresponds to a hemodynamic disturbance and is due to primary or secondary venous malformation of the bones.

Secteur dorsal du foie

The dorsal sector extends in front and to the sides of the inferior vena cava, separating the caval axis from the main liver (excepting superiorly the entrance of the main hepatic veins into the vena cava). The two elements, dorsal sector and retro-hepatic portion of the vena cava, actually make a single unit. It is made of two segments: left (segment I) larger than the Spieghel lobe, right (segment IX) incorporated in the posterior surface of the right liver. The “caudate process” is not a peculiar element: it is nothing else than the inferior margin of segment IX: the breadth gives information on the size of segment IX. The dorsal sector is the midportion of the posterior liver, it is absolutely independent of the right and left livers separated by the main portal fissure. Portal pedicles are numerous and ascendant, they arise from the posterior margin of the transverse portal arch (from right to left: segment VII vein, right lateral vein, right portal vein, left portal vein, segment II vein). The size of the dorsal sector is variable, and can be appreciated by an antero-posterior index. A voluminous sector may be a problem for the surgeon. Segment IX can be divided in three subsegments: IXb under the interval between the right superior hepatic vein and the middle hepatic vein (longer branches can ascend and supply a small portion of the upper surface in front of the vena cava), IXc under the very broad right superior vein, and posteriorly IXd, linked to segment VII. Only segment I and subsegment IXb receive branches from the right and from the left livers. Hepatic veins enter directly the caval axis, some enter the main hepatic veins. The dorsal sector is a large anastomosis between efferent veins and the vena cava. Anteriorly segment I is in contact with segment IV but also with segment VIII, subsegments IXb and IXc with segment VIII and IXd with segment VII. The fissurai limit is difficult to locate. Posteriorly division of the triangular and coronary ligaments, section of the dorsal hepatic veins, the right middle and inferior veins allow separation of the liver from the posterior abdominal wall and the inferior vena cava, so the surgeon can reach the dorsal sector. A remarkable error has been commited when the main hepatectomies were described: the dorsal sector was not known and the caudate lobe was considered as a part of the left liver. Actually the dorsal liver is a separate entity covering the inferior vena cava which has no connexion with the main liver; when the main portal fissure is opened up to the anterior surface of the vena cava, the dorsal sector is opened vertically. Interruption of the pedicles must also be considered. For example, in a left hepatectomy, the left portal pedicle is divided, all the left branches for subsegment IXb (which will be preserved) are interrupted; but the left branches from the right portal pedicle are not interrupted and will bleed when the dorsal sector is divided. When splitting the liver for transplantation, some difficulties can occur, especially with the right transplant. A main practical interest is the possible propagation to the dorsal ducts of hilar carcinoma.

Angiography of Hemodialysis Fistulas

This chapter reviews the basic technique, indications, and problems with angiography of hemodialysis fistulas. Incorporated in the chapter is a description of the angiographic technique, particularly via the brachial artery or direct graft puncture, or puncture of the efferent shunt vein as in cases of Cimino-Brescia fistulas. The normal vascular findings in the shunt as well as recognition of the abnormal findings are described.

The lymphatics of the liver

An overview of our current knowledge of the hepatic lymph vessels is given, and the different lymph node stations that are related to the liver are described. The lymphatics of the liver itself can be divided into a superficial and a deep system. The superficial vessels are mainly situated in the liver capsule, the deep ones follow the triads of Glisson or the efferent hepatic veins. There are no direct communications between spaces in the liver parenchyma and the first lymphatic capillaries, which end blindly in the surrounding connective tissue. Nevertheless, the perisinusoidal space of Disse, the space of Mall, directly adjacent to the outer limiting plate of the parenchyma, and the space of Comparini, surrounding the sublobular hepatic veins can be regarded as prelymphatic spaces from which the hepatic lymph could originate. The extracellular matrix in the space of Disse is apparently continuous with the extraparenchymal areas of the connective tissue. Collagens and proteoglycans offer a morphological pathway for the transport of fluid, the physiological prerequisites of which are discussed.

DSA mit maschinell injiziertem Kohlendioxid: Tierexperimentelle Ergebnisse

Carbon dioxide was used as an intra-arterial contrast medium by mechanical injection in 10 pigs. 127 angiographic examinations of 114 vascular territories were carried out and 93 were successful. A mechanism providing even gas volumes was chosen to obtain reproducible volume and pressures when using a compressible medium such as gas. Gas pressure is exponentially correlated with volume and volumes of 20-50 cm3 at 1000 mbar adequate for filling various infradiaphragmatic vascular areas. In parenchymatous organs, gas filling is seen only as far as third order arteries. The reason for this is escape of gas through preexisting arteriovenous fistulae into the efferent veins.

Tumor necrosis factor-α release during systemic reaction in cold urticaria

Primary cold urticaria (PCU) characterized by the association of urticaria, angioedema, and sometimes a shock-like reaction after cold exposure, is usually considered to be linked with histamine and prostaglandin D 2 release by mast cells. To determine the involvement of cytokines, we studied the release of tumor necrosis factor-α (TNF-α) in the blood of the efferent vein after immersion of the hand in chilled water. Five patients with PCU were compared with a control population (three patients with nonphysical urticaria and three healthy subjects). Among patients with PCU who underwent the cold immersion test, two exhibited a shock-like reaction with a large urticarial plaque (patients 1 and 2), one had only a mild cutaneous reaction, and two had no reaction. Patient 1 was reevaluated after 6 months of treatment with H 1 and H 2 antihistamines: he did not respond to this challenge. All controls were strictly negative. Histamine was released within the first minute after the challenge in the three patients with PCU, but at a higher level for the two patients who had a systemic reaction. TNF-α was undetectable in the blood of the patient with only a mild cutaneous reaction, whereas TNF-α release was observed for the two patients with a systemic reaction, 2 and 6 minutes after the end of the cold immersion test. The two other patients and the control subjects released neither histamine nor TNF-α. In parallel, pathologic and immunohistochemical (with a rabbit anti-TNF-α antibody) studies were performed on skin biopsy specimens collected 10 minutes after ice-cube test. Four patients with PCU who had positive ice-cube test results were studied, as well as patient 1 after treatment, who did not respond to the ice-cube test. The pathologic study revealed that mast cells were the only cells infiltrating the dermis in PCU and that most of mast cells were degranulated but only in the four patients with positive ice-cube test results. Immunohistochemical study revealed that only mast cells were stained by anti-TNF antibody (90% ± 2.5%). In conclusion, besides histamine release, cold exposure in PCU induces a concomittent TNF-α release by mast cells. Its detection in blood suggests that in addition to histamine, TNF-α may be implicated in the shock-like reaction in cold urticaria.

Vascularization of the pineal gland in the crow.

The blood vascularization in the pineal gland of the crow was investigated in detail using a vascular corrosion cast technique and by scanning electron microscopy. The pineal gland received two afferent arteries on either side, each artery arising from the A. cerebralis caudalis (CC) which supplied its branches to the hemisphere. The pineal gland of the crow was so highly vascularized as to be suggestive of its high metabolic and endocrine activities. The efferent veins drained into the Sinus occipitalis and the Sinus sagittalis dorsalis. There was a direct vascular connection between capillaries of the stalk of the gland and those of the Plexus choroideus.

Effect of cardiac sympathetic nerve stimulation on acutely ischemic myocardium. A comparison with the response to exogenous noradrenaline.

To assess the integrity of an adrenergic nervous function in acute myocardial ischemia, the contractile response of the ischemic region to cardiac sympathetic nervous stimulation (CSNS) was measured in comparison that with to exogenous noradrenaline (NA) infusion. In 13 anesthetized open chest mongrel dogs, haemodynamic changes, segmental wall motion, and the concentration of NA in the efferent coronary vein were measured. CSNS was performed by electrically stimulating the left ansa subclavia. Data concerning baseline values, values during CSNS, and those obtained during NA infusion both before and up to 5 h after coronary occlusion were compared. Regional myocardial blood flow of the ischemic region was also measured using the H+ clearance method. Systolic expansion with coronary occlusion was not changed or augmented by CSNS. However, improvement was observed in all experiments when NA infusion was used. The percent change of systolic shortening, indicating the response of segmental wall motion to CSNS, decreased soon after occlusion, recovered temporarily within 30 min after occlusion, but did not improve throughout the period after 60 min. The decrease of NA overflow into the efferent vein by CSNS showed a biphasic pattern; reduction occurring immediately after occlusion and again 3-5h after occlusion. Throughout these experimental studies it was considered that the preserved responses to the exogenous injected NA represented the contribution of presynaptic factor.

Monoaminergic innervation of the rat kidney: a quantitative study

The sympathetic innervation of the renal tubules and vasculature was characterized by measuring the overlap of accumulations of autoradiographic grains (AAGs) on these structures in autoradiograms of kidney sections from rats injected with tritiated norepinephrine. AAG overlap was used as an indirect measure of the innervation of those structures. The renal vasculature showed x 4.5 more AAG overlap than observed on renal tubules. The greatest amount of AAG overlap occurred on afferent arterioles, followed by efferent arterioles, interlobular arteries, cortical capillaries, arcuate arteries, and renal veins. High concentration of AAGs occurred along the vascular bundles of the outer stripe. In the tubular nephron the proximal tubule had the greatest amount of AAG overlap, followed by the cortical thick ascending limb of Henle, the connecting tubule, the distal convoluted tubule, and the collecting duct. It was found that afferent arterioles had significantly higher mean density of AAG overlap than efferent arterioles for the superficial, midcortical, and juxtamedullary (vascular bundles excluded) renal cortex. There was consistently more AAG perimeter facing the interstitium than overlapping the vasculature. These observations, together with the ultrastructural distribution of synaptic vesicles in varicosities, suggest that the interstitium might be an additional pathway of neurotransmitter access to the effector structures.

The correlation between clinical and Duplex ultrasound parameters and the development of complications in arterio-venous fistulae for haemodialysis

In a 2 year prospective study of the fate of arterio-venous haemodialysis fistulae, the influence of several clinical and non-invasive measured variables in 90 patients on maintenance haemodialysis was evaluated. A total of 58 Brescia/Cimino fistulae, 30 graft fistulae and two elbow fistulae were investigated by means of Duplex ultrasound scanning. Sixty-two out of these 90 patients had no problems with their AV fistulae, 28 developed 29 complications, including poor flow (six), thrombosis (seven), venous hypertension (eight), false aneurysm formation (four), distal ischaemia (two) and puncture problems (two). Univariate statistical analysis was performed on a number of clinical variables including diabetes, previous access surgery, type of fistula, duration of functioning fistula, congestive heart failure, peripheral arterial disease, age and sex. Results indicated that the type of fistula, previous access surgery, congestive heart failure and sex were significantly correlated to the development of poor flow and thrombosis (flow-related complications). Measurement of the maximal systolic frequency, end-diastolic frequency and the frequency ratio in the brachial artery Doppler spectrum, was of prognostic value in discriminating between non-complicated fistulae and those which developed flow-related complications. The total number of fistula stenoses (greater than 50% diameter reduction), detected by the Duplex scan, also correlated with the rate of thrombosis and poor flow. The presence of peripheral arterial disease and the number of stenoses in the efferent veins were of predictive value for the development of venous hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

A study on the venous drainage of 150 cerebral arteriovenous malformations as related to haemorrhagic risks and size of the lesion

In this paper we study the venous drainage of 150 cerebral arteriovenous malformations (AVM), correlating the number of efferent veins with the symptoms of clinical onset and with the size of the lesions. Statistical analysis demonstrates that those AVM's which in the angiograms show only one draining vein have a high risk of haemorrhage. As the number of drainage veins increases, this bleeding risk decreases, becoming quite low in angiomas with multiple drainage veins, which we denominate "medusa-head angiomas". Statistics also demonstrate that small angiomas (less than 2 centimeter on diameter) usually have only one drainage vein, thus carrying a high risk of haemorrhage. As their size increase, so do the number of veins, and the possibility of haemorrhage decreases.

Cardiovascular anatomy and physiology of the black‐lip abalone, Haliotis ruber

AbstractThe anatomy of the cardiovascular system of Haliotis ruber is described on the basis of observations from dissection, routine histology, and scanning electron microscopy of vascular casts and critical‐point dried tissue. The finest channels, lacunar tissue spaces, were around 10 μm and appear to lack an endothelial lining. A vascular connection, which exists between the cephalic arterial sinus and the cephalopedal venous sinus, may allow redirection of blood back to the heart during circumstances in which blood flow through the pedal vessels is prevented. 5‐Hydroxytryptamine (5‐HT) immunoreactive nerves were observed in atrial and ventricular walls, pericardium, cephalic arterial sinus, and afferent ctenidial vein. In unrestrained animals, pairs of in vivo pressure measurements were made from the right atrium, the ventricle, the pericardial chamber, the right efferent ctenidial vein, and the renal sac. All sites showed pulsatile pressures of low magnitude. Ventricular systolic:diastolic pressures were typically 8:4 cm water. In unrestrained animals, heart‐rate responses to changes in water temperature and pO2 were established and show H. ruber to be an imperfect regulator with respect to O2. Structural characteristics of the heart and vascular anatomy, pressure measurements, and heart rate are discussed in relation to whole animal function.

Duplex ultrasound scanning in the assessment of arteriovenous fistulas created for hemodialysis access: Comparison with digital subtraction angiography

The results of duplex ultrasound scanning for the diagnosis of stenoses in Brescia-Cimino arteriovenous fistulas and graft arteriovenous fistulas created for hemodialysis access are reported. Quantitative Doppler spectrum analysis of 64 arteriovenous fistulas was correlated with the outcome of digital subtraction angiography. The best Doppler parameter for the detection of a stenoses was the peak systolic frequency. In graft arteriovenous fistulas the use of this parameter resulted in a diagnostic accuracy of 86%, a sensitivity of 92%, and a specificity of 84% in the detection of stenoses. In Brescia-Cimino arteriovenous fistulas the diagnosis of anastomotic stenoses was possible with a diagnostic accuracy of 81%, a sensitivity of 79%, and a specificity of 84%. Measurement of peak systolic frequency ratios or end-diastolic frequencies had no additional diagnostic value for the detection of stenoses. The diagnosis of efferent vein stenoses was very accurate with duplex investigation (accuracy 96%, sensitivity 95%, and a specificity of 97%. We conclude that duplex scanning is a promising noninvasive method for the diagnosis of stenoses in arteriovenous fistulas created for hemodialysis access.

Anatomie fonctionnelle du foie du fœtus humain: applications à l'échographie

The anatomy of the liver of the human fetus was established on the basis of cadaveric techniques, but its study has been transformed by obstetric ultrasonography. This work is based on a personal study of the normal morphology of the liver of the human fetus and on a review of the current literature, particularly with regards to vascularization. The liver is the digestive organ whose rudiments appear earliest and which develops most rapidly. The development of the liver and its functional segmentation are determined by the oxygenated blood flow in the umbilical vein. The extent of each hepatic territory depends on the quantity of umbilical flow, which determines its development and ensures its function. The fetal liver occupies a very large proportion of the abdominal cavity. It is a vascular organ, closely moulded to the walls of the abdominal cavity and the viscera in contact with it. The left liver is a little more bulky than the right liver and is developed mainly transversely. The morphology of the normal fetal liver appears quite uniform. The intrahepatic umbilical vein and the venous axis prolonging it to the right have a remarkably constant arrangement, well demonstrated by ultrasonography. An assessment of the anatomic features of the afferent veins, the ductus venosus and the efferent veins gives some idea of the conditions of the intrahepatic venous circulation in the human fetus that remain to be demonstrated. At birth, ligature of the umbilical v. brings about a sudden change in the hepatic circulation, resulting in temporary morphologic and functional modifications in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Islet Vasculature in Atrophic Pancreas

Islet vasculature was studied in rats rendered dietarily copper-deficient, a regimen that effects progressive acinar atrophy while leaving islets and ducts intact. Scanning electron microscopy of corrosion casts produced from Mercox injected rats was used to analyze islet angioarchitecture in the atrophied gland. The results indicate that with the onset of acinar atrophy, the vasculature of islets remained intact despite loss of insuloacinar interconnectivity. With atrophy of the dense acinar vascular matrix, three populations of islets could be distinguished according to their size and vascular structures: (a) All small islets (40-150 microns in diameter) were found to have exclusively serial vasculature since no postcapillary collecting venules were found directly continuous with parallel efferent veins. (b) A second population of intermediate size islets (160-250 microns) was found to have serial vessels in addition to postcapillary collecting venules that were directly continuous with larger interlobular veins indicative of a parallel mode of microcirculation. (c) All larger islets (260-700 microns) were also found to have both serial as well as parallel microcirculatory patterns based upon the coexistence of both types of postcapillary venules within the same islet. In all cases, postcapillary venules, which normally link islet capillaries to peri-insular acinar plexuses, were continuous with veins that extended through lipomatous lobules devoid of acini to link with branches of interlobular veins. It is proposed that the functional integrity of islet blood flow remains in the atrophied pancreas because of preservation of both serial and parallel microcirculation that facilitate normal glucose-stimulated insulin secretion in the atrophied pancreas, as demonstrated in an earlier study. Furthermore, it is suggested that analysis of the atrophied state of the gland provides a valid comparative model with which to study islet angioarchitecture and microcirculation in the normal gland.

Renal blood vascular system in the elasmobranch, Raja erinacea Mitchill, in relation to kidney zones.

The arrangement and structure of renal blood vessels were studied in a marine skate with injection of silicone rubber and methacrylate resin after intravenous administration of epinephrine and perfusion fixation. The methacrylate casts were investigated with the scanning electron microscope. Histology was performed by light and transmission electron microscopy of serial sections. The course of the blood vessels is described in relation to the renal zones of lateral bundles and mesial tissue. Each nephron performs two loops in the lateral bundles and two coilings in the mesial tissue before it joins the collecting duct system. The lateral bundles contain an elaborate countercurrent arrangement of neck segment, proximal tubule segment PIa, early distal tubule segment, and collecting tubule. Within the bundles, the nephron portions are associated with a blind-ended central vessel, which is connected with the venous sinuses of the mesial tissue. The microcirculatory bed around the bundles is supplied with arterial blood via small bundle arteries that originate from the intrarenal arteries in parallel to the afferent arterioles of the glomeruli. The efferent arterioles of the glomeruli convey their blood to the peritubular sinuses of the mesial tissue, which is largely irrigated with venous blood of the renal portal system. The mesial tissue, containing the proximal tubule segments PIb and PII, intermediate segment, and late distal tubule segment LDTb, receives venous blood from the caudal vein and the lateral musculature via afferent renal and intrarenal veins and from the efferent arterioles of the glomeruli and venules of the microcirculation of the bundles. The sinuses are drained by efferent renal veins via efferent intrarenal veins. By comparing the renal structures of the skate with those of dogfish, a unique type of circulation--as related to nephron segments, renal zones, and fine structure of the wall of the vessels--is revealed in marine elasmobranchs of different evolutionary levels.