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PubMedDate not supplied

Microcirculation in the elderly.

Studies on microcirculation in the elderly include observations in the small vessels of the bulbar conjunctiva and of the nailbed with respect to a classification of the findings according to a number of semeiologic criteria (diameter and shape alterations, terminal capillary network, intravascular red cell aggregation). In vascular diseases of the elderly there are typical alterations of the capillaroscopic findings in the bulbar conjunctiva and in the nailbed, particularly in cases of arteriosclerosis, arterial hypertension, diabetic microangiopathy, heart failure, ischemic myocardiopathies. During the treatment with some vasoactive drugs (nicotinic acid and its derivatives, buflomedil, CPD-choline) there are marked modifications of the small conjunctival vessels, with evident dilatations, appearance of collaterals, increased homogeneity of the blood flow, better evidence of the capillary network and reduction of intravascular red cell aggregation.

Aged↗
PubMed1976

Activation of intravascular coagulation by endotoxin: the significance of granulocytes and platelets.

The importance of granulocytes and/or platelets in endotoxin-induced generalized intravascular coagulation was studied as well as thrombocytopenic rabbits. Neutropenia and thrombocytopenia were induced by oral administration of busulphan. Generalized intravascular coagulation, as indicated by renal glomerular microclot formation, was initiated by two intravenous injections of endotoxin. Granulocyte counts before the second injection of endotoxin were most significantly related to activation of intravascular coagulation whereas platelet counts either before the first or second injection of endotoxin were not definitely related to the activation process. Renal glomerular microclots occurred in rabbits after two injections of endotoxin even when the platelet counts were between 500 and 5000/mul. These experiments indicated that granulocytes but not platelets are essential to the activation of endotoxin-induced intravascular coagulation.

Animals↗
PubMed1994

[Use of colloids in acute hypovolemia].

In Denmark several natural and synthetic colloids are available. Natural colloids are fresh frozen plasma (FFP) and human albumin (HA). Both are ideal as plasma expanders, but FFP can carry infectious agents and HA is quite expensive. The synthetic colloids or modified macromolecules are the dextrans (Macrodex (MD) and Rheomacrodex (RMD)), Haemaccel (HC), and Haes-steril (HS) in 6 and 10% solutions. HC has few indications because of a questionable volume expansion and a relatively high frequency of side effects. RMD is useful in cases of compromised regional blood flow. HS 10% and HA 20% are hyperoncotic and are effective in redistributing interstitial fluid to the intravascular space. HS and MD are both effective as volume substitutes. In addition HS and MD have beneficial side effects such as an inhibition of erythrocyte aggregation and inhibition of leucocyte marginalisation. Furthermore, MD has an anti-thrombotic effect. However, MD has in contrast to HS a dose dependent effect on the bleeding time. HS and MD are effective in restoring the colloid osmotic pressure and can in many cases replace HA in treatment of hypovolaemia.

Acute Disease↗
PubMed1991

Rouleaux formation in sickle cell traits.

Rouleaux formation of washed red blood cells (r.b.c.s) from subjects with sickle cell trait (HbAS) was measured by the rapid coagulation method. The r.b.c.s were suspended in the donor's native plasma or in 1.3% dextran in phosphate-buffered Ringer solution at pHs of 6.5, 7.4 and 8.2. HbAS cells showed more rouleaux formation than HbAA (normal) cells in plasma (P less than 0.005). Plasma fibrinogen concentration of HbAS and HbAA subjects did not differ significantly (mean 2.9, s.d. 0.7 g l-1 for both groups). In the dextran solution, HbAS cells were more aggregable at pH 6.5 but less at pH 8.2 than HbAA cells. There was no significant difference in dextran-induced aggregation between the two groups of cells at pH 7.4. The results suggest that HbAS subjects may be more prone to intravascular sludging and stasis and that this risk may be enhanced by reduction in pH of blood.

Adult↗
PubMed1967

Hypofibrinogenaemia in metastatic carcinoma of the prostate: suppression of systemic fibrinolysis by haparin.

In a patient with generalized prostatic carcinoma and hypofibrinogenaemia heparin infusion on four occasions abolished systemic fibrinolysis as determined by euglobulin clot lysis time, bovine fibrin plate assay, thromboelastography, and immunoelectrophoretic demonstration of fibrinogen split products. The pathogenesis of hypofibrinogenaemia in cases of prostatic carcinoma and the possibility of a direct heparin effect on fibrinolysis are discussed. Despite the lack of histological evidence for intravascular coagulation, the findings are considered additional evidence for the view that fibrinolysis in this syndrome may be secondary to intravascular coagulation.

Afibrinogenemia↗
PubMed1991

Dynamic structure of blood flow in microvessels.

The present article summarizes the author's perennial research on the flow of red blood cells in microvessels, the major determinant of rheological properties of blood in the microcirculation. Two main patterns of blood flow structure in microvessels, in the smallest arteries and veins and in the capillaries are described. The red cell concentration (hematocrit) in the blood flowing in microvessels undergoes regular alterations with changes of blood flow rate and vessel diameter in the microvascular beds. Further, the red blood cell concentration and flow velocity gradients are found in the cross-section of microvessels that should considerably affect the blood rheological properties in the microcirculation. In addition, radial displacements and blood velocity fluctuations of red cells in the flow are discovered in the larger microvessels during ischemic decrease of blood flow rate. The main factor disturbing the normal blood flow structure, and hence the normal rheological properties of blood, is the intravascular aggregation of red blood cells, which is to be diagnosed and eliminated in patients with blood rheological disturbances.

Erythrocyte Aggregation↗
PubMed1996

Immune cell migration through the arterial wall in the murine lung during a pulmonary inflammatory response.

Perivascular accumulation of leukocytes in the lung was induced by intratracheal administration of sheep erythrocyte antigen to primed mice. The route of migration of intravascular leukocytes to the perivascular space in the lung, in particular from arteries, and the structure of lymphatic vessels among the aggregated leukocytes were examined by transmission electron microscopy. Leukocytes--lymphocytes, granulocytes, monocytes and macrophages--were demonstrated to adhere to the endothelial surface and to migrate between endothelial cells to reach the internal elastic lamina of arteries. Becoming conspicuously constricted, the leukocytes penetrate through this elastic lamina. They further migrate through the smooth muscle layer to the interstitium, passing through the external elastic laminar region. At 2 days after antigen administration, dilated lymphatic vessels containing large numbers of leukocytes in the lumen and bearing endothelial gaps open to the interstitium began to be seen. The lymphatic walls were more convoluted and richer in pinocytotic vesicles than those prior to antigen challenge. This study confirms the light microscopic findings by Curtis et al. (1990) that arteries, besides veins, venules and capillaries, may represent a major route of inflammatory cell entry into the lung parenchyme in an acute and vigorous immune response. In addition, lymphatic vessels were suggested to be newly formed for the transport of fluid and immune cells from the sites of inflammation in the lung.

Animals↗
PubMed1980

The dextrans--clinical data.

The use of dextrans in clinical practice are mainly based on the following effects: 1. Plasma volume effects 2. Flow Promotion 3. Antithrombotic effects. The dextrans are the only plasma volume substitute with the antithrombotic effect but this discussion will only deal with their effects on plasma volume and flow. The effect on plasma volume--the colloid supported intravascular volume--can be calculated as ml of water held in circulation per gram circulating colloid--for dextran 70 around 20 ml/g, for albumin 18 ml/g and for plasma protein 12-13 ml/g. After infusion of a plasma volume substitute the volume effect depends on dose injected, molecular weight distribution, rate of disappearance from the intravascular department mainly via the kidneys. The clinical experience of a reliable plasma volume expansion can be demonstrated in animal experiments comparing different infusion fluids. The effect on erythrocyte aggregation depends on kind of substance and molecular weight distribution. The flow promoting effect is mainly due to restoration of plasma volume but also related to hemodilution and aggregation. The vasoconstriction seen in shock can be counteracted essentially with colloid supported plasma volume expansion. The supposed influence of the dextrans on the kidney function in some clinical cases has been investigated experimentally.

Blood Circulation↗
PubMed1985

Vasoactive agents and production of thrombosis during intravascular coagulation. 2. alpha-Adrenergic stimulation: effects and mechanisms.

The mechanism whereby norepinephrine elicits thrombosis during intravascular coagulation was investigated further in rabbits given a 4 h infusion of thrombin (1 NIH unit/kg/min). Norepinephrine (3 micrograms/kg/min) combined with thrombin produced glomerular capillary thrombosis in all animals as compared to 4.3% with thrombin alone. Alpha-adrenergic receptors mediated this effect, as indicated (a) by prevention of glomerular thrombosis by dibenzyline but not by methysergide, and (b) by failure of histamine or acetylcholine combined with thrombin to induce the phenomenon. However, in combination with thrombin, these two agents induced duodenal mucosal microthrombosis. Study of the glomerular circulation with colloidal carbon showed that norepinephrine elicits severe glomerular capillary stasis in thrombin treated rabbits; the vasomotor reaction precedes increased fibrinogen consumption and focal deposition of fibrin in the glomeruli. Pretreatment with dibenzyline prevented glomerular stasis and reduced fibrinogen consumption. The phagocytic activity of the reticulo-endothelial system was increased 7 times by thrombin infusions, with or without norepinephrine. We conclude that stimulation of the alpha 1-adrenergic receptors triggers glomerular thrombosis by production of severe glomerular stasis which localizes formation of thrombi in the dilated vessels. These results provide a rational explanation for the role of alpha-adrenergic stimulation in the endotoxin-induced generalized Shwartzman reaction and outline some of the mechanisms and agents implied in the selection of the target organs for thrombosis during intravascular coagulation.

Animals↗
PubMed1981

[Effect of an infusion with middle molecular weight hydroxyethyl starch (HAES-steril 10%) on the flow properties of blood in healthy probands].

Ten healthy volunteers received infusions of 500 ml of a 10% solution of middle-molecular-weight hydroxy-ethyl-starch (HES 200, HAES-steril 10%) within 30 min. Measurements of hemorheological parameters before and up to 3 hrs after infusion revealed a statistically significant decrease of whole-blood viscosity and a slight, but also statistically significant increase of plasma viscosity. RBC filterability and RBC aggregation remained unchanged. The data presented show that despite of a relatively high molecular weight of the infused HES-solution which is responsible for the relatively long intravascular persistence, the flow properties of blood as a whole are positively influenced.

Adult↗