Recent advances in organ microcirculation research

This review article dealt with progress in the research of gastroenterological organ microcirculation in Japan. It must be emphasized that this remarkable progress particularly in intravital microcirculatory observations at organ level is attributable to great improvement of microscopic devices combined with computerized system, development of new techniques for measuring microcirculatory blood flow and pioneering of a variety of fluorescent and isotope-labelled tracers. Little attention has been directed toward the fact that microvascular manifestations are perhaps the earliest signs of "cells and tissues" dysfunction in disease processes. The microvasculature undergoes a substantial remodeling not only in vascular wall structures, but also in network characteristics themselves especially in chronic disease. Those microvascular alterations in an organ system, which primarily originate in adaptations to the microenvironmental changes, would lead to the chronicity and self-perpetuation of disease. As has been noted in the IVth World Congress for Microcirculation organized by the Japanese Society for Microcirculation, which was held in Tokyo, July 26-30, 1987, further progress has been made in the research of organ microcirculation in the gastroenterological and other fields. It is the cornerstone for better understanding of the pathogenesis of organ diseases to clarify the earliest alterations in the microvasculature of an organ system from a combined aspect of microhemo- and microlymphocirculation using the newly developed techniques for microcirculation study.

Characterization of the syndrome of small and large intestinal variceal bleeding

Massive bleeding from jejunal varices in a young alcoholic with cirrhosis and portal hypertension ceased following a portocaval shunt. Although rare, bleeding from small or large bowel varices has a high mortality. In 62 cases, small or large bowel varices are almost always associated with a predisposing condition including previous abdominal surgery and portal hypertension from cirrhosis or other causes. Hematochezia without hematemesis and nonbleeding esophageal varices generally occur. Angiography is the best diagnostic test.

Infiltrative fibrosis with acute hemorrhagic intestinal infarction: association with a peritoneovenous shunt

This article describes an unusual complication of acute hemorrhagic infarction of the gastrointestinal tract that developed in a 53-year-old man 3 years after a Denver peritoneovenous shunt was implanted for control of cirrhotic ascites. Infiltrative fibrosis, which involved the bowel and mesentery and surrounded its blood vessels, was the cause of the infarction. A spectrum of this fibroproliferative disease in patients with cirrhosis with ascites and peritoneovenous shunts is described, and possible pathogenetic mechanisms are discussed.

Arterial occlusion causing large bowel infarction--a reflection of clotting diathesis in SLE

The patient, a 44-year old woman with systemic lupus erythematosus, (SLE), developed infarction of the bowel and spleen after occlusion of the inferior mesenteric and splenic arteries, necessitating colectomy and splenectomy. She had had previous cerebral thromboses and a lower limb deep vein thrombosis. Histological examination of the involved vessels showed the presence of thrombus only with the total absence of any vasculitis. The patient demonstrated antibodies to phospholipid - the "lupus anticoagulant" (LA) and antibodies to cardiolipin in serum, both strongly associated with thromboses.

[Results of therapy of acute mesenteric vascular occlusion]

From 1979 to 1984 39 patients were operated on for acute mesenteric ischemia. The purpose of this retrospective study was the documentation of the therapeutic results and discussion of the value of a second-look operation and postoperative angiography. Proximal occlusion of SMA in 33 patients (85%) resulted in extended bowel infarction, whereas segmental infarction due to peripheral occlusion was found in 15%. The hospital mortality was 85%. Operative procedure consisted of revascularisation (18%), bowel resection (18%), revascularisation and resection (10%) and explorative laparotomy (18%). The second-look operation as a routine procedure has been replaced by a postoperative angiogram. Laparotomy was performed in case of reocclusion of SMA or clinical signs.

Measurement of blood flow through surgical anastomosis using the radioactive microsphere technique

Two different radioactive microspheres (141Ce and 46Sc) were used to measure blood flow to an area of the large intestine in dogs before and after a surgical resection was performed with surgical staples. The healing of an anastomosis is theoretically related to the blood flow to the anastomotic site. Blood flow studies were conducted in three dogs using this technique. The average blood flow preoperatively was 0.558 mL/minute per gram and 1.04 mL/minute per gram postoperatively. The standard deviation was +/- 0.16. These results indicate a statistically significant (P less than .05) increase in blood flow at the anastomotic site six days after anastomosis when compared with the blood flow to the same area before any surgical procedures.

Temporary ischaemia of a large bowel segment induced by degradable starch microspheres in man

Degradable starch microspheres were used to induce temporary ischaemia measured by electromagnetic flowmetry in colon segments during bowel resection. Severe reversible ischaemia free from unwanted side effects was induced in eight of nine patients. In one of the five patients where the tumour was included in the microsphere-embolised tissue volume no reduction in blood flow was seen. Segmental enteric ischaemia induced by degradable starch microspheres in man seems safe and may be useful for radioprotective purposes in clinical radiation therapy.

Changes in intestinal blood flow during the development of chronic large bowel obstruction

The effect of chronic progressive distal large bowel obstruction on intestinal blood flow was studied in 12 mini-pigs. Blood flow was measured by the techniques of xenon133 clearance and intracardiac injections of radiolabelled microspheres. Intestinal blood flow was increased in the left colon and ileum but decreased in the caecum. Blood was shunted from the mucosa to the muscle layers. The results suggest that primary anastomosis of the obstructed left colon is not contraindicated by haemodynamic considerations.

Ultrastructure of the intestinal mucosa in pigs experimentally inoculated with an edema disease-producing strain of Escherichia coli (0139:K12:H1)

The intestinal tissues from 11 pigs orally inoculated with Escherichia coli (E. coli, 0139:K12:H1) were examined by transmission electron microscopy. The colonization of E. coli along the small intestinal mucosa was found in seven principals without any major changes in the enterocytes from day 2 to day 7 after inoculation when the experiment was terminated. Lesions of vessels of the intestinal mucosa could be detected as early as two days after inoculation and persisted until the experiment was terminated. Lesions consisted of endothelial swelling and vacuolation, subendothelial fibrin deposition, perivascular edema, microthrombus formation, endothelial proliferation, and necrosis of the tunica media. The possible pathogenesis of the disease is discussed.

A method for the determination of microvascular volume in tissue samples

An estimate of the volume of the microvascular bed in injected tissue specimens of human bowel has been made by measuring the concentration of injected contrast material using X-ray fluorescent analysis. The contrast medium used was barium sulphate and this completely fills the microvasculature in excised specimens. The concentration of barium in excised tissue samples has been determined by measuring the ratio of gamma-ray induced X-ray fluorescence in the barium to the 90 degree Compton scattered 140 keV gamma rays from a collimated 99Tcm source. Barium concentration was estimated in tissue samples from 45 specimens of normal bowel and 11 specimens of radiation damaged bowel. The radiation group showed a highly significant reduction (p less than 0.001) in barium concentration and therefore vascular volume. The mean percentage error for barium concentration measured on two separate occasions in 45 randomly selected tissue samples was 5%.

Restricted transport of cationic macromolecules across intestinal capillaries

The charge-selective properties of intestinal capillaries were investigated by measuring steady-state lymph-to-plasma concentration ratios (L/P) of endogenous and exogenous macromolecules of comparable molecular size but different charge. The steady-state L/P values for endogenous lactate dehydrogenase isoenzymes (LD1-LD5) decreased with increasing isoelectric point. The osmotic reflection coefficient for LD1, the most negative isoenzyme studied, was 0.71 +/- 0.01; that for the most positive isoenzyme (LD5) was 0.95 +/- 0.01. The steady-state L/P for an exogenous molecule, neutral dextran, was 0.51 +/- 0.04; the L/P for the positively charged dextran of similar size was 0.25 +/- 0.04. The results indicate that intestinal capillaries behave as a positively charged barrier that reduces blood-lymph exchange of cationic macromolecules and enhances the exchange of anionic molecules.

[Effect of various vagal functional conditions on the blood flow of abdominal organs]

In 21 mongrel dogs blood flow was measured in different gastrointestinal organs under fasting conditions, vagal stimulation with 2-desoxy-D-glucose and vagotomy. The examinations were performed in anaesthesia with the microsphere method. Basal blood flow was found in corpus, fundus and antrum below 0,5 ml/g X min, whereas in the region of the small curvature values of 0,7 ml/g X min were observed. Vagotomy decreases flowrates especially in the mucosa of the stomach except in the region of the antrum. There a significant increase was measured. The stimulated bloodflow shows a similar effect by a vagotomy, but on an elevated lovel. Observations over the time of 3 weeks revealed that bloodflow changes due to vagotomy are not long lasting over that time. Only a decrease can be observed in the region of the antrum. Also in the other abdominal organs bloodflow changes due to vagotomy are terminated to a short time interval. Except the bloodflow changes in the gallbladder lasts longer than 4 weeks. From this investigation the conclusion can be drawn that vagotomy does not cause long lasting and radical bloodflow changes in the abdomen.

Arterial inflammatory-cell infiltration in Crohn's disease

Histologic sections from 70 cases of Crohn's disease were studied for the presence of acute and/or chronic inflammatory cells in the walls of arteries and arterioles. Vessels in areas of marked inflammation were not considered. Similarly, arteries showing chronic obliterative changes, without inflammatory cells, were excluded. More than 20% of the cases showed either chronic inflammatory-cell infiltration, acute and chronic inflammatory-cell infiltration, obliterative changes with inflammatory-cell infiltration, or granulomatous inflammation. These changes need to be recognized as a part of Crohn's disease; furthermore, physicians should refrain from designating patients as having one of the primary vasculitides in the absence of extraintestinal evidence of disease.

[Structural mechanisms of regulation of the lympho-microcirculatory system]

The lymphatic vessels in total macro-microscopical preparations of various human organs and those in some laboratory animals have been injected with silver nitrate solution. There are various morphological structures that are capable to regulate the lymph flow and outflow rate in the microcirculatory lymphatic bed. A peculiar role belongs to the lymphatic postcapillaries (V. V. Kuprianov) that possess valve-sluices. The structural mechanism of the microcirculatory lymphatic bed circulation are in many respects similar to those of the hemomicrocirculatory bed. A model demonstrating a morphofunctional unit in the microcirculatory lymphatic bed is proposed. It is an integrate part of the hemomicrocirculatory bed module.

Neonatal intestinal oxygen consumption during arterial hypoxemia

In 12 chronically catheterized neonatal lambs, we determined intestinal tract blood flow (Qi) and O2 consumption (VO2i) at O2 contents of arterial blood (CaO2) ranging from 15.3 to 3.2 ml O2/dl blood. We measured Qi with the radioactive microsphere technique and computed intestinal O2 delivery (DO2i), VO2i, and O2 extraction (VO2i/DO2i) using the Fick principle. In lambs breathing air, mean Qi = 214 ml X min-1 X 100 g intestine-1, DO2i = 27.0 ml O2 X min-1 X 100 g-1, O2 extraction = 21%, and VO2i = 5.6 ml O2 Xmin-1 X 100 g-1. During reductions in CaO2, Qi and DO2i decreased. Intestinal O2 extraction increased sufficiently, however, so that VO2i was maintained over the range of CaO2 from 15.3 to about 6.5 ml O2/dl blood. VO2i was independent of Qi at Qi greater than 160 ml X min-1 X 100 g-1. When CaO2 was reduced below values of 6.5 ml O2/dl blood, corresponding to Qi less than 160 ml X min-1 X 100 g-1, VO2i fell in association with increases in the H+ concentration difference between mesenteric venous and arterial blood. These data indicate that the intestinal tract of the neonatal lamb can meet its oxygen requirements when O2 supply varies over a wide range. When O2 availability reaches a critically low level, intestinal anaerobic metabolism develops as the O2 supply to the neonatal intestinal tract becomes inadequate for the O2 demand.