| Ventriculocisternal Perfusion Studies in the Monkey. III. Sources of Error in Measuring Cerebrospinal Fluid Formation, |
JUN 1976 |
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| Authors:
A. N. Martins; N. Newby; T. F. Doyle; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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 | Ventriculocisternal perfusion is regarded as a precise method of measuring the rate of formation of cerebrospinal fluid (CSF) but possesses inherent potential sources of error not commonly appreciated. Using the technique to measure CSF formation rate in the rhesus monkey, rate changes were observed when none was expected. Most puzzling has been the steady decline of CSF formation rate at 4 percent each hour during the final 5 hours of ... |
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| Ventriculocisternal Perfusion Studies in the Monkey. II. PCO sub 2 and the Rate of Formation of Cerebrospinal Fluid, |
MAY 1976 |
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| Authors:
A. N. Martins; T. F. Doyle; N. Newby; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Changes in cerebrospinal fluid formation rate (Vf) with hypocapnia and hypercapnia were measured by the ventriculocisternal perfusion technique in 24 rhesus monkeys anesthetized with nitrous oxide. In addition cerebral blood flow (CBF) was measured by the hydrogen clearance method. The results indicate that in the monkey variations of PCO2 within broad physiologic limits, which are sufficient to cause large changes in CBF, have little effect on Vf. This observation is ... |
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| Further Studies in Spinal Cord Autoregulation. |
APR 1976 |
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| Authors:
A. I. Kobrine; T. F. Doyle; N. Newby; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Using the hydrogen clearance method to measure focal spinal cord blood flow (SCBF) in the rhesus monkey (Macaca mulatta), the effect of high cervical cord section on the phenomenon of autoregulation was studied. Laminectomies were performed at the T7-T11 as well as the C1-C2 levels. The spinal cord was completely severed at C1-C2. Under normocapnic conditions, SCBF was then measured in the thoracic spinal cord over a wide range of ... |
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| Hyperemia and Edema in the Monkey Spinal Cord Following Injury: Modified by Histamine Antagonists. |
MAR 1976 |
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| Authors:
T. F. Doyle; A. I. Kobrine; A. N. Martins; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Using the hydrogen washout technique, blood flow in the lateral funiculus of the spinal cord of rhesus monkeys was measured before and after a contusion sufficient to render the animals paraplegic. In untreated animals, the blood flow increased 1 hour after injury to almost twice the normal flow rate (17.6 to 31.8 ml/min per 100 g). When the animals were pretreated with histamine antagonists (chlorpheniramine, an H sub 1 antagonist, ... |
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| The Effect of a Simulated Subarachnoid Hemorrhage on Cerebral Blood Flow in The Monkey. |
MAR 1976 |
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| Authors:
A. N. Martins; T. F. Doyle; N. Newby; A. I. Kobrine; A. Ramirez; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| The hydrogen clearance method was used to measure local and total cerebral blood flow (CBF) in the rhesus monkey before and for 5 hours after a simulated subarachnoid hemorrhage (SAH). CBF remained stable after SAH unless SAH was associated with a fall in cerebral perfusion pressure. In addition, cerebrovascular resistance did not increase after SAH. These results suggest that vasoactive agents in fresh whole blood, and the arterial spasm they ... |
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| The Effect of Intracisternal Phentolamine on Cerebral Blood Flow after Simulated Subarachnoid Hemorrhage. |
DEC 1975 |
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| Authors:
A. N. Martins; N. Newby; T. F. Doyle; A. I. Kobrine; A. Ramirez; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| The hydrogen clearance method was used to measure total and focal blood flow (CBF) in the monkey before and for 5 hours after a simulated subarachnoid hemorrhage (SAH). Some monkeys also received 0.2-1.0 mg/kg phentolamine intracisternally 3 hours after SAH. SAH did not change cerebrovascular resistance, but as cerebral perfusion pressure decreased, CBF fell transiently. Phentolamine injected intracisternally 3 hours after SAH produced a significant fall in arterial blood pressure; ... |
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| Physiologic Control of Spinal Cord Blood Flow, |
OCT 1975 |
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| Authors:
A. I. Kobrine; T. F. Doyle; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| The hydrogen clearance technique was used to measure spinal cord blood flow (SCBF) in the rhesus monkey to test the hypothesis of autoregulation in the spinal cord. Laminectomies were performed at the T9-T10 level, and 250-micrometers diameter platinum electrodes were placed through the intact dura, 2 mm into the spinal cord, midway between the midline and lateral borders. Flows were calculated from the desaturation curves of inhaled hydrogen. When the ... |
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| Ventriculocisternal Perfusion Studies in the Monkey. I. Comparison of Radioiodinated (125I) Serum Albumin and Blue Dextran as Indicators to Measure Rate of Formation of Cerebrospinal Fluid, |
OCT 1975 |
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| Authors:
A. N. Martins; A. Ramirez; A. I. Kobrine; T. F. Doyle; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| The characteristics of two nondiffusible indicators, 125I labeled albumin (RISA-125) and blue dextran, were compared by using them simultaneously to measure rate of formation of cerebrospinal fluid (Vf) in in vitro experiments and in a series of ventriculocisternal perfusion experiments in rhesus monkeys. Mean Vf calculated from the dilution of RISA-125 was 37.6 microliters/min; the Vf calculated from the corresponding dilution of blue dextran was 37.1 microliters/min. In the in ... |
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| Histamine-Induced Hypotension Modified by H1 and H2 Antagonists. |
JUN 1975 |
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| Authors:
T. F. Doyle; T. A. Strike; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| The hypotensive response of monkeys to exogenous histamine was measured when the histamine was given without antagonist, after chlorpheniramine (10 mg/kg) or mepyramine (10 mg/kg), and after these two antagonists in combination with burimamide (20 mg/kg). The dose of histamine needed to elicit a 50 percent maximal response was: without antagonist, 0.115 micrograms/kg; after chlorpheniramine, 13.5 micrograms/kg; after chlorpheniramine and burimamide, 23.5 micrograms/kg; after mepyramine, 23.0 micrograms/kg; and after mepyramine ... |
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| Initial Slope Index of Total Cerebral Blood Flow Measured by Hydrogen Clearance: A Pragmatic Evaluation. |
JUN 1975 |
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| Authors:
T. F. Doyle; A. N. Martins; A. I. Kobrine; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| An initial slope index of total cerebral blood flow, measured by hydrogen clearance from torcular blood, shows high correlation with flows calculated by bicompartmental analysis. In 247 flow measurements done on 41 rhesus monkeys, a linear regression analysis between these two methods of calculating flow shows a correlation coefficient of 0.9280 with a standard error about y values of plus or minus 7.63. The initial slope index is not only ... |
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| The Effects of Traumatic Injury on Spinal Cord Blood Flow. |
DEC 1974 |
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| Authors:
T. F. Doyle; A. I. Kobrine; A. N. Martins; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Using the hydrogen clearance technique, the effect of direct crush injury on blood flow was measured in the lateral white matter and central gray matter of the spinal cord of the adult rhesus monkey. Three measurements were made: at the site of injury (T8-T10), 1 cm above and 1 cm below. After injury, blood flow in the central gray matter declined markedly. However, flow in the lateral funiculus increased 100 ... |
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| Norepinephrine Effects on Early Postirradiation Performance Decrement in the Monkey. |
NOV 1971 |
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| Authors:
J. E. Turns; T. F. Doyle; C. R. Curran; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Monkeys, trained to perform a discrete trial, cued avoidance task, were used to measure the effectiveness of intravenously infused norepinephrine in preventing the hypotension and performance decrement which usually follows 3000- to 30,000-rad doses of radiation. After a 4000-rad dose of mixed gamma-neutron radiation, 10 animals were infused with norepinephrine at a rate designed to maintain mean arterial blood pressure at approximately 100 mm Hg; for comparison 10 control animals ... |
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| Radiation Inactivation of Histamine in Aqueous Solution and in Plasma. |
JUL 1971 |
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| Authors:
T. F. Doyle; S. L. Bradley; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| Dilute solutions of histamine in water and plasma were given 140- to 38,000-rad doses of pulsed mixed gamma-neutron radiation. Histamine activity of the solutions was bioassayed using guinea pig ileum. Inactivation of the histamine in water was apparent at doses of 2000 rads or more. Different concentrations of histamine receiving the same dose of radiation showed an inverse relation between concentration and inactivation. Histamine in plasma showed less than 10 ... |
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| Effect of an Antihistamine on Early Transient Incapacitation of Monkeys Subjected to 4000 Rads of Mixed Gamma-Neutron Radiation, |
SEP 1970 |
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| Authors:
T. F. Doyle; J. E. Turns; T. A. Strike; ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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| An antihistamine, chlorpheniramine maleate, was used in monkeys to ameliorate the severe hypotension and to prevent signs of the early transient incapacitation (ETI) frequently associated with supralethal doses of ionizing radiation. Twenty-five monkeys (Macaca mulatta) were given 4000 rads of mixed gamma-neutron radiation delivered as a single pulse of approximately 50 miliseconds duration. Eight of the animals served as controls and received only normal saline injections; 10 animals were each ... |
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