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Biomedical subjects

D W Beck

Publications and source records attributed to D W Beck.

36 records · Page 2Linked to original sources
PubMed1985

Insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle.

Experiments were performed to test the hypothesis that insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle. Cultured endothelium and smooth muscle derived from isolated mouse cerebral microvessels were exposed to insulin in serum-free medium, and [3H]-thymidine incorporation in the cells was measured. Up to 40-fold stimulation of DNA synthesis in endothelium and fourfold stimulation in smooth muscle were observed. Stimulation became maximal in both cell types at an insulin concentration of approximately 10(4) ng/ml, although an effect was observed at much lower concentrations. Similar concentrations of insulin produced a less-dramatic (approximately twofold) increase in both endothelial and smooth muscle cell numbers. This effect of insulin, observed in microvessel endothelium and smooth muscle, but not in bovine aortic endothelium, emphasizes another way in which large- and small-vessel endothelia appear to differ.

Animals↗
PubMed1984

Glial cells influence polarity of the blood-brain barrier.

Polarity has been shown to exist at the blood-brain barrier (BBB) with respect to Na+-dependent neutral amino acid transport. A situation similar to the endothelial-astrocyte relationship existing at the BBB can be produced by growing cultured cerebral endothelium on one side of a filter and C6 glial cells on the other in an enclosed double chamber. In this setting 3H-alpha-methylaminoisobutyric acid transport can be demonstrated and is more rapid from the glial surface across the endothelium, as compared with transport in the opposite direction. The observation supports a glial influence on BBB polarity in this system.

Aminoisobutyric Acids↗
PubMed1983

Uptake of adenosine into cultured cerebral endothelium.

Adenosine uptake by cultured cerebral endothelium is a carrier-mediated process. The Km value for adenosine uptake is 5.0 microM and the vmax is 1.15 nmol/min/mg cell protein. The uptake system is inhibited by the adenosine analog 2-chloroadenosine at low adenosine concentrations. The results prove the existence of a nucleoside transport system associated with cerebral capillary endothelium.

2-Chloroadenosine↗
PubMed1983

The role of the macrophage in microvascular regeneration following brain injury.

Although macrophages are the earliest cells found in association with vessels in an area of cerebral injury, the role of this cell in the subsequent regeneration of the microvasculature is unknown. DNA synthesis in cerebral endothelial cells at the margin of injury of mouse brain was assayed by quantitation of the labeling indices from 3H-thymidine autoradiographs of normal animals and animals with X-ray-induced leukopenia. A mean endothelial cell labeling index of 10% in the irradiated animals was significantly lower than control animals (26.7%) (p less than 0.01). In vitro tissue culture studies utilizing peritoneal macrophages and cerebral endothelium were then used to isolate the endothelial response to macrophages and their products. Macrophage-conditioned media did not stimulate cerebral endothelial proliferation when evaluated by a growth factor assay, although this macrophage-conditioned media did stimulate DNA synthesis in fibroblasts and bovine aortic endothelium. A migration study of the cerebral endothelial cells utilizing an agarose technique showed enhanced random migration in the presence of macrophage-conditioned media compared to controls (p less than 0.01). The results indicate that macrophages do not directly stimulate proliferation of cerebral endothelial cells, but influence their migration. A loss of contact inhibition and subsequent DNA synthesis and replication may follow.

Animals↗
PubMed1983

Uptake of adenosine by cultured cerebral vascular smooth muscle cells.

Adenosine uptake by cerebral smooth muscle cells is a carrier-mediated process. The Km value for adenosine uptake is 10.0 microM and the Vmax is 0.95 nmol/min-mg cell protein. This uptake system is inhibited by the adenosine analog 2-chloroadenosine at low adenosine concentrations. These results prove the existence of a nucleoside transport system associated with cerebral smooth muscle.

Adenosine↗
PubMed1982

Treatment of ischemic deficits from vasospasm with intravascular volume expansion and induced arterial hypertension.

In 58 patients with progressive neurological deterioration from angiographically confirmed cerebral vasospasm after spontaneous subarachnoid hemorrhage, arterial hypertension was induced in an attempt to improve their deficits. The most effective regimen consisted of intravascular volume expansion, blockade of the vagal depressor response, and the administration of antidiuretics and vasopressor agents. With this protocol, arterial blood pressure could be sustained at high levels for prolonged periods. Neurological deterioration was reversed in 47 patients, transiently in 4; permanent improvement occurred in 43. Complications experienced during therapy included pulmonary edema, dilutional hyponatremia, aneurysmal rebleeding, coagulopathy, hemothorax, and myocardial infarction. Elevating systemic arterial pressure in states of cerebrovascular insufficiency resulting from vasospasm is safe if meticulous attention is paid to physiological, biochemical, and hematological parameters, with the exception that it may be hazardous in the presence of an untreated ruptured or intact aneurysm. Intravascular volume expansion and induced hypertension are effective in reversing ischemic deficits from vasospasm provided that treatment commences before cerebral infarction and that adequate pressures are maintained for a sufficient period. The production of a hypervolemic state by the use of colloid and crystalloid infusion accompanied by atropine blockade of the vagal depressor response and blunting of the diuresis with vasopressin enables arterial pressure to be elevated for longer than 1 week.

Adolescent↗
PubMed1981

Complications of spinal drainage in the management of cerebrospinal fluid fistula.

Continuous cerebrospinal fluid (CSF) drainage may be used in the treatment CSF fistula. The procedure, however, is not without risk. Marked gradients between the intracranial and intraspinal CSF pressures and intravasation of air through an unsealed fistula may produce serious neurological problems. The use of continuous CSF drainage requires an alert, informed nursing staff to avert catastrophe.

Adult↗
PubMed1979

An intrinsic coagulation pathway inhibitor in a 3-year-old child.

An intrinsic coagulation pathway inhibitor with acitivty against factor XI was detected in the plasma of a 3-year-old child, following a respiratory infection. The inhibitor was present transiently, but it was clinically significant and was manifiested by extensive bruises. Abnormalities of clotting and the bruising tendency disappeared simultaneously without treatment before the inhibitor could be definitively characterized. It was possibly the consequence of an adenovirus infection, as an elevated adenovirus titer was demonstrated in the patient's blood. It is possible that inhibitors of this type are more common sequelae of viral infections than realized, and perhaps a systematic effort should be made to detect them and to define their etiology and mechanism of action.

Adenovirus Infections, Human↗
PubMed1979

Surgical treatment of giant aneurysm of vertebral-basilar junction.

A giant aneurysm of the vertebro-basilar junction is reported. It was successfully treated by ligation of the left vertebral artery, temporary occlusion of the right vertebral and basilar arteries, and evacuation of the aneurysm, following which the neck of the aneurysm was clipped.

Adult↗
PubMedDate not supplied

Effect of intracarotid hyperosmolar mannitol on cerebral cortical arterioles--a morphometric study.

The morphometric response of cerebral cortical arterioles to intracarotid hyperosmolar mannitol was assessed utilizing a technique of rapid freezing of rat brain tissue in vivo. A significant decrease in the wall to lumen (W/L) ratio was noted in the small parenchymal arterioles (20-49 mu) (p less than .0001) ipsilateral to the mannitol infusion. Larger arterioles showed a decreased W/L ratio but this change was not significant. Control infusion of 0.9% NaCl resulted in no change in arteriolar caliber. These results indicate that intracarotid hyperosmolar mannitol causes a direct vasodilatory response in small cerebral cortical arterioles.

Animals↗
PubMedDate not supplied

Demonstration of adenosine receptors on mouse cerebral smooth muscle membranes.

Adenosine receptors have been identified on brain cortical membranes and microvascular preparations. However, they have not been demonstrated on specific microvascular elements in isolation. 2-3H-chloroadenosine was used as a ligand to investigate the presence of adenosine receptors on isolated mouse cerebral smooth muscle membranes. The binding studies reveal the presence of a high affinity binding site with a Kd value of 33.3 nM and a maximal binding capacity (Bmax) of 283 fmol/mg protein. These findings demonstrate that there is an adenosine receptor on cerebral smooth muscle membranes.

2-Chloroadenosine↗
PubMedDate not supplied

Acute effect of angiographic contrast medium on cortical specific gravity after middle cerebral artery occlusion in rats.

Early angiography after cerebral arterial occlusion has been cited as potentially detrimental. This investigation evaluates the effect of acute angiographic contrast medium administration on the cortical edema induced by middle cerebral artery (MCA) occlusion. Sixteen rats underwent MCA occlusion, and after 1 hour half the rats underwent ipsilateral internal carotid injection of meglumine diatrizoate, whereas the remainder underwent cervical internal carotid exposure only. Six rats had only sham operations on the MCA and internal carotid, and 4 other rats served as normal controls. Cortical specific gravity was measured to reflect cerebral edema 4 hours after occlusion or sham operation. Specific gravity of the lateral frontal cortex in the hemisphere ipsilateral to occlusion was 1.0396 +/- 0.0011 (mean +/- SEM) when no angiographic contrast medium was administered, significantly less (p less than 0.01) than in rats exposed to contrast medium (specific gravity 1.0442 +/- 0.0005). The latter value was not significantly different from normal. Other cortical areas on the side of the contrast medium injection were also relatively dehydrated compared with normal controls. Early meglumine diatrizoate administration after MCA occlusion results in a decrease in cerebral cortical edema, possible by inducing an osmotic gradient that draws water from the extravascular space.

Animals↗