THE EFFECT OF AGE ON THE ELASTICITY OF THE MAJOR BRAIN ARTERIES

1965 ◽  
Vol 43 (2) ◽  
pp. 185-202 ◽  
Author(s):  
Douglas E. Busby ◽  
Alan C. Burton
Keyword(s):  
High Pressures ◽  
Mean Value ◽  
Collagen Fibers ◽  
Peripheral Arteries ◽  
Volume Data ◽  
Maximum Slope ◽  
Brain Arteries ◽  
Autopsy Specimens ◽  
Collagenous Fibers ◽  
The Brain

In previous work on peripheral arteries the law of Laplace has been applied to the pressure–volume data to yield the elastic constants and interrelation of function of elastin and collagenous fibers in the wall, and the changes with age. Similar analysis of major brain arteries has been made on autopsy specimens, aged 2 to 90. Volume (micrometer syringe) and pressure (electromanometer) in arterial segments were accurately measured. Absolute volumes were obtained by collapsing the artery with negative pressure, and the "unstretched circumferences" of the vessel were deduced from the curves. Tension–circumference curves were constructed. These showed the characteristic increasing slope (increased "elastance" or "stiffness") with increasing degree of stretch, interpreted as successive "recruitment" of collagen fibers as they reach their unstretched length.Increases in arterial length with distension were very small and negligible in vessels older than 30 years. Maximum slope (stiffness) was reached at pressures in the physiological range. The maximal stretch was 26 to 38% for vessels aged 30 to 90 years. This is less than for peripheral arteries, except those over 80 years old.Ageing showed itself mainly in reduction of the stretch required to bring 50% of the collagen fibers to their unstretched length, i.e. in the "degree of slackness". This was 30% stretch for younger vessels, 20% for the older. Unlike the peripheral arteries, the brain arteries show no significant increase with age in the maximal stiffness (related to their total collagen content). The mean value of the Young's modulus of the wall at high pressures was 1.93 ± 0.67 × 107 dynes/sq.cm. No significant change in thickness of the wall or lumen diameter with age was found.It is concluded that the major brain arteries are less distensible than peripheral arteries of comparable diameter, particularly in youth. Distensibility decreases with age, mainly because the "degree of slackness" of the collagen fibers is reduced. At physiological pressures the major resistance to distension is due to the collagen fibers rather than to the elastin fibers, which appear histologically to be less abundant, except in the elastica interna, than in peripheral arteries.

Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

1990 ◽  
Vol 48 (3) ◽  
pp. 274-275
Author(s):  
Enrico D.F. Motti ◽  
Hans-Georg Imhof ◽  
Gazi M. Yasargil
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Corrosion Casts ◽  
Cerebral Microcirculation ◽  
Pial Arteries ◽  
Random Occurrence ◽  
Brain Arteries ◽  
Homogeneous Network ◽  
The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

Association of Variables of Coagulation, Fibrinolysis and Acute-phase with Atherosclerosis in Coronary and Peripheral Arteries and those Arteries Supplying the Brain

1995 ◽  
Vol 73 (03) ◽  
pp. 374-379 ◽  
Author(s):  
Jürgen Heinrich ◽  
Helmut Schulte ◽  
Rainer Schönfeld ◽  
Ekkehart Köhler ◽  
Gerd Assmann
Keyword(s):  
Acute Phase ◽  
Coronary Atherosclerosis ◽  
Plasminogen Activator Inhibitor ◽  
Arterial Disease ◽  
Plasma Fibrinogen ◽  
Base Line ◽  
Peripheral Arteries ◽  
Brain Vessels ◽  
The Brain ◽  
D Dimer

SummaryWe investigated the vessel status of coronary and peripheral arteries and those arteries supplying the brain in 929 consecutive male patients admitted to a coronary rehabilitation unit. The severity of coronary atherosclerosis was scored using coronary angiography. Changes in extracranial brain vessels and manifest cerebrovascular disease (CVD) were determined by B-mode ultrasound and Doppler examination. Peripheral arterial disease (PAD) was diagnosed using base-line and stress oscillography. We assessed variables of coagulation, fibrinolysis, and the acute phase response.There was a significant increase in plasma fibrinogen, plasminogen, d-dimer and C-reactive protein (CRP) with increasing severity of coronary heart disease. Compared to men with unaffected arteries, men with 3 diseased coronary arteries had 58% greater d-dimer concentrations. Patients with CVD and PAD, respectively, also had significantly higher fibrinogen, d-dimer and CRP concentrations. We did not find an association between plasminogen activator inhibitor activity and the severity of coronary atherosclerosis.In conclusion, plasma fibrinogen, d-dimer and CRP concentrations were significantly related to atherosclerosis in the coronary, peripheral and extracranial brain arteries.

Analysis of Red Cell Mass and Plasma Volume in Patients With Polycythemia

2005 ◽  
Vol 129 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Mordechai Lorberboym ◽  
Naomi Rahimi-Levene ◽  
Helena Lipszyc ◽  
Chun K. Kim
Keyword(s):  
Body Weight ◽  
Plasma Volume ◽  
Cell Mass ◽  
Mean Value ◽  
Whole Body ◽  
Red Cell ◽  
Volume Data ◽  
Red Cell Mass ◽  
The Mean ◽  
Iodine 125

Abstract Context.—Polycythemia describes an increased proportion of red blood cells in the peripheral blood. In absolute polycythemia, there is increased red cell mass (RCM) with normal plasma volume, in contrast with apparent polycythemia, in which there is increased or normal RCM and decreased plasma volume. In order to deliver the appropriate treatment it is necessary to differentiate between the two. Objective.—A retrospective analysis of RCM and plasma volume data are presented, with special attention to different methods of RCM interpretation. Design.—The measurements of RCM and plasma volume in 64 patients were compared with the venous and whole-body packed cell volume, and the incidence of absolute and apparent polycythemia was determined for increasing hematocrit levels. Measurements of RCM and plasma volume were performed using chromium 51–labeled red cells and iodine 125–labeled albumin, respectively. The measured RCM of each patient was expressed as a percentage of the mean expected RCM and was also defined as being within or outside the range of 2 SD of the mean. The results were also expressed in the traditional manner of mL/kg body weight. Results.—Twenty-one patients (13 women and 8 men) had absolute polycythemia. None of them had an increased plasma volume beyond 2 SD of the mean. When expressed according to the criteria of mL/kg body weight, 17 of the 21 patients had abnormally increased RCM, but 4 patients (19%) had a normal RCM value. Twenty-eight patients had apparent polycythemia. The remaining 15 patients had normal RCM and plasma volume. Conclusions.—The measurement of RCM and plasma volume is a simple and necessary procedure in the evaluation of polycythemia. In obese patients, the expression of RCM in mL/kg body weight lacks precision, considering that adipose tissue is hypovascular. The results of RCM are best described as being within or beyond 2 SD of the mean value.

scholarly journals The arteries of the brain base in the degu (Octodon degus Molina 1782)

2014 ◽  
Vol 59 (No. 7) ◽  
pp. 343-348 ◽  
Author(s):  
W. Brudnicki ◽  
B. Skoczylas ◽  
R. Jablonski ◽  
W. Nowicki ◽  
A. Brudnicki ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Basilar Artery ◽  
Internal Carotid ◽  
Cerebral Arteries ◽  
Left Vertebral Artery ◽  
Brain Arteries ◽  
Middle Cerebral Arteries ◽  
The Brain ◽  
Synthetic Latex

The brain arteries derived from 50 adult degu individuals of both sexes were injected with synthetic latex introduced with a syringe into the left ventricle of the heart under constant pressure. After fixation in 5% formalin and brain preparation, it was found that the sources of the brain’s supply of blood are vertebral arteries and the basilar artery formed as a result of their anastomosis. The basilar artery gave rise to caudal cerebellar arteries and then divided into two branches which formed the arterial circle of the brain. The internal carotid arteries in degus, except for one case, were heavily reduced and did not play an important role in the blood supply to the brain. The arterial circle of the brain in 48% of the cases was open from the rostral side. Variation was identified in the anatomy and the pattern of the arteries of the base of the brain in the degu which involved an asymmetry of the descent of caudal cerebellar arteries (6.0%), rostral cerebellar arteries (8%) as well as middle cerebral arteries (12%). In 6% of the individuals double middle cerebral arteries were found. In one out of 50 cases there was observed a reduction in the left vertebral artery and the appearance of the internal carotid artery on the same side. In that case the left part of the arterial circle of the brain was supplied with blood by an internal carotid artery, which was present only in that animal.

Magnetic Resonance Imaging of Cerebral Central Sulci: a Study of Monozygotic Twins

1998 ◽  
Vol 47 (2) ◽  
pp. 89-100 ◽  
Author(s):  
I. Bonan ◽  
A.M. Argenti ◽  
M. Duyme ◽  
D. Hasboun ◽  
A. Dorion ◽  
...  
Keyword(s):  
Intraclass Correlation ◽  
Monozygotic Twins ◽  
Correlation Coefficients ◽  
Mean Value ◽  
Resonance Imaging ◽  
Mr Images ◽  
Central Sulcus ◽  
Intraclass Correlation Coefficients ◽  
Left Right Asymmetry ◽  
The Brain

AbstractThe cerebral central sulci, seat of the sensorimotor cortex, vary anatomically in form, length and depth among individuals and present a left/right asymmetry. The purpose of this work was to measure central sulcus's lengths, at the surface and in-depth, in each hemisphere of monozygotic twins in order to evaluate the influence of environmental factors on the morphometry and asymmetry of this structure. A measurement technique on MR images of the brains using 3 D software was developed. Two operators applied this technique to measure central sulcus lengths at the surface of the brain and in-depth in each hemisphere. Besides the fact that the technique developed gave high Intraclass Correlation Coefficients (ICC) for the surface lengths (mean value 0.94), and slightly less high for the in-depth length (mean value 0.87), we found a weak (from 0.57 to 0.73 for raw data) but significant ICC between homologous sulci in pairs of twins. In addition, the ICC for asymmetry indices were not significant. Hence, if central sulcus morphometry is in part genetically influenced, these results show that nongenetic factors are nonetheless important in their development.

Age-Related Changes in Scleral Material Properties of the Monkey Eye

2008 ◽  
Author(s):  
Michaël J. A. Girard ◽  
Jun-Kyo F. Suh ◽  
Michael Bottlang ◽  
Claude F. Burgoyne ◽  
J. Crawford Downs
Keyword(s):  
Intraocular Pressure ◽  
Material Properties ◽  
Lamina Cribrosa ◽  
Collagen Fibers ◽  
Visual Signals ◽  
Type I ◽  
Retinal Ganglion ◽  
Age Related ◽  
The Brain ◽  
Age Related Changes

The sclera is the outer shell and principal load-bearing tissue of the eye, which consists primarily of avascular lamellae of collagen fibers. Ninety percent of the collagen fibers in the sclera are Type I, which provide the eye with necessary mechanical strength to sustain intraocular pressure (IOP). In the posterior sclera, there is a fenestrated canal, called the optic nerve head (ONH), through which the retinal ganglion cell axons pass transmitting visual signals from the retina to the brain. The opening of the ONH is structurally supported by a fenestrated connective tissue called the lamina cribrosa.

Reference sample method for cardiac output and regional blood flow determinations in the rat

1976 ◽  
Vol 40 (3) ◽  
pp. 472-475 ◽  
Author(s):  
A. B. Malik ◽  
J. E. Kaplan ◽  
T. M. Saba
Keyword(s):  
Cardiac Output ◽  
Regional Blood Flow ◽  
Reference Sample ◽  
Peripheral Arteries ◽  
Blood Flows ◽  
Tissue Weight ◽  
Regional Blood Flows ◽  
Sample Method ◽  
The Brain ◽  
Cardiac Output Measurements

The reference sample method was used for simultaneous determinations of cardiac output and regional blood flows in conscious rats. Microspheres (15 +/- 5 mum in diam) labeled with strontium-85 were injected into the left ventricle and known volumes of reference sample were withdrawn from peripheral arteries. The calculated cardiac output measurements agreed with the previously reported values in rats. The percent distribution of the cardiac output to the brain, intestinal bed, and lungs were different from the reported values obtained in the rats using larger spheres. These differences may be related to the use of smaller spheres and to differences in the preparation. The absolute regional flows to various organs expressed in terms of milliliters per minute per gram tissue weight were also determined. The results indicate that the reference sample method can be applied to smaller mammals for determinations of regional flows and cardiac output.

Cerebral hemodynamics in angioma patients: an intraoperative study

1987 ◽  
Vol 67 (6) ◽  
pp. 822-831 ◽  
Author(s):  
Werner Hassler ◽  
Helmuth Steinmetz
Keyword(s):  
Doppler Sonography ◽  
Perfusion Pressure ◽  
Normal Brain ◽  
Content Type ◽  
Vasomotor Reactivity ◽  
Brain Arteries ◽  
Normal Perfusion Pressure Breakthrough ◽  
The Brain ◽  
Intravascular Pressure ◽  
Flow Velocities

✓ Local hemodynamics were investigated during 33 operations for cerebral arteriovenous malformation (AVM). In all cases, microvascular Doppler sonography was used to measure flow velocities and vasomotor reactivity to CO2 changes. Intravascular pressure recordings were performed in six patients. The AVM feeders had low intravascular pressure, high flow velocity, low peripheral stream resistance, and very poor vasomotor reactivity. Remote brain arteries showed no abnormalities. Doppler findings in arterial branches of AVM feeders that supplied normal brain indicated arteriolar dilation in their peripheral distribution. On removal of the angiomas, the arteries that formerly supplied them showed a return to normal intravascular pressure, whereas flow velocities dropped far below normal in these vessels. Remote arteries and branches of the former AVM feeders supplying the brain did not show any signs of impaired vasomotor reactivity following angioma removal. The results are in contrast to the normal perfusion pressure breakthrough theory.

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