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Biomedical subjects

M E Carey

Publications and source records attributed to M E Carey.

At least 19 recordsLinked to original sources
PubMed1992

Central and peripheral biogenic amine effects of brain missile wounding and increased intracranial pressure.

This study was performed to ascertain the acute effects of brain missile wounding on brain-stem and hypothalamic biogenic amines in a group of cats anesthetized with pentobarbital (40 mg/kg). Brain wounding is associated with a concomitant increase in intracranial pressure (ICP); to separate the effects of elevated ICP alone from the effects of wounding, a second group of cats had ICP artificially increased from a normal level of approximately 5 mm Hg to approximately 140 mm Hg by infusion of mock cerebrospinal fluid into the cisterna magna. In both groups, significant epinephrine depletions (47% to 74%) occurred in the nucleus tractus solitarius, area A1C1, locus ceruleus, raphe nuclei, and posterior hypothalamus. Epinephrine levels were also significantly decreased in the anterior hypothalamus in the wounded cats. In addition, both brain wounding and artificially induced ICP increases caused significant decreases of norepinephrine in the posterior hypothalamus, and of serotonin, 5-hydroxyindoleacetic acid, dopamine, and homovanillic acid in the raphe nuclei. Only brain wounding, however, caused significant reductions of norepinephrine, dopamine, and homovanillic acid in the nucleus tractus solitarius and area A1C1. The plasma catecholamine levels resulting from brain wounding or artificially induced ICP increases were dissimilar only in the amount of time required to attain maximum plasma levels, with the wounded animals responding faster. It is concluded that the hypothalamic and brain-stem biogenic amine changes resulting from either brain wounding or increased ICP alone are reflective of a stress response. Brain-stem distortion caused by brain wounding did not appear to be a factor and monoaminergic systems appeared to remain intact despite a severe and eventually lethal brain injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Cerebral cardiovascular and respiratory variables after an experimental brain missile wound.

Brain missile wounding (BMW) affects brainstem and medullary cadiorespiratory functions leading to immediate systemic hypertension, bradycardia, and apnea. Secondary complications may also occur because of subsequent changes in systemic and intracranial physiological variables. To delineate the immediate and secondary effects of BMW, we monitored changes in several cerebral and cardiorespiratory parameters in pentobarbital-anesthetized spontaneously breathing cats before wounding and up to 90 min afterward. Total and regional cerebral blood flow (rCBF) and cardiac output (CO) were measured (microsphere technique) and arterial blood was sampled for pH, PO2 and PCO2 once before BMW and one to four times afterward. Mean arterial blood pressure (MABP), intracranial pressure (ICP), cerebral perfusion pressure (CPP = MABP - ICP), electrocardiogram (ECG), heart rate (HR), and electroencephalogram (EEG) were continuously recorded. Respiratory frequency (f), tidal volume (Vt), and ventilation (V) were recorded during each flow measurement and periodically throughout the experiment. Four unwounded cats served as controls and 15 cats were wounded at 1.4 J fronto-occipitally through an intact cranium. Unwounded cats showed no significant changes in any physiological variable measured during a 100 min experimentation period. Four wounded cats survived a 90 min post-BMW period and had only a transient brainstem effect including a 50% increase in MABP concurrently with 50% reductions in the f and HR. Nonsurvivors (11 of 15) lived from 1 to 41 min after wounding. These cats initially demonstrated similar changes in MABP, f, and HR to survivors, but these variables remained unstable, possibly indicating a persisting brainstem damage. Apnea accounted for death in 10 of 11 nonsurvivors. Although the primary brainstem effect might have existed in all nonsurvivors, it appears that only one cat died from reduced respiration alone. Others had one or several postwounding secondary complications: abruptly increased ICP producing a negative CPP, extreme reductions in CO or CBF and ventilation. Cardiac arrest occurred once. Thus, post-BMW mortality cannot be consistently ascribed to the impairment of a single physiological variable.

Analysis of Variance↗
PubMed1991

Coagulation changes after an experimental missile wound to the brain in the cat.

Platelet studies (total number and platelet aggregation) and coagulation assays (fibrinogen, factor VIII, and anti-thrombin III) were performed on systemic arterial blood of four control and four experimental adult cats that sustained a penetrating missile injury to the brain. Among the brain-wounded, a significant decrease in the total number of platelets and aggregates occurred 120 minutes after injury. Fibrinogen levels decreased significantly in the brain-wounded animals by 240 minutes after injury and continued declining until the end of the 6-hour experiment. No significant changes occurred in factor VIII and antithrombin III levels in wounded as compared with control animals. These results indicate that blood coagulation factors are altered following a missile wound to the brain. These alterations may, occasionally, lead to clinically manifested bleeding disorders, specifically disseminated intravascular coagulation. Thus, early analysis and control of the coagulation system in the brain-wounded patient should be considered to prevent and treat bleeding disorders in the setting of penetrating head injury.

Analysis of Variance↗
PubMed1990

Brain edema following an experimental missile wound to the brain.

Brain edema occurs after brain injury and may be life threatening. The occurrence and type of brain edema, its magnitude, and time course have never been ascertained following a missile wound to the brain. We therefore measured the development of brain edema in a series of cats in which a right cerebral hemisphere wound was made with a 2.0 mm, 31.7 mg steel sphere with a velocity of 240-300 m/s (0.9-1.4 J). The entire brain was surveyed for postwounding brain edema by determining the wet weight minus dry weight. Brain edema was seen to develop only in the white matter about the missile wound track in the injured cerebral hemisphere. There, brain water rose from 66 to 73%; white matter sodium also increased significantly from approximately 150 mEq/kg dry weight to 254 mEq/kg dry weight. Potassium levels remained essentially unchanged. This vasogenic edema was relatively mild, peaked at 24-48 h after wounding, and resolved spontaneously within a week without specific treatment. We infer that brain edema following an uncomplicated cerebral missile wound in the human brain is also mild, self-limited, and may resolve spontaneously without special treatment.

Animals↗
PubMed1990

Brain edema after an experimental missile wound.

We have developed an experimental model to study cerebral pathophysiology associated with a missile wound to the brain. After wounding, vasogenic edema occurs about the missile wound track in the injured cerebral hemisphere. This edema is relatively mild, does not appear life-threatening, peaks at 48 hr after wounding, and spontaneously resolved in 1 week.

Animals↗
PubMed1989

Experimental missile wound to the brain.

Among civilians in the United States, 33,000 gunshot wound deaths occur each year; probably half of these involve the head. In combat, head wounds account for approximately half of the immediate mortality when death can be attributed to a single wound. No significant reduction in the neurosurgical mortality associated with these wounds has occurred between World War II and the Vietnam conflict, and very little research into missile wounds of the brain has been undertaken. An experimental model has been developed in the anesthetized cat whereby a ballistic injury to the brain may be painlessly reproduced in order that the pathophysiological effects of brain wounding may be studied and better treatments may be designed to lower the mortality and morbidity rates associated with gunshot wounds. Prominent among physiological effects observed in this model was respiratory arrest even though the missile did not injure the brain stem directly. The incidence of prolonged respiratory arrest increased with increasing missile energy, but arrest was often reversible provided respiratory support was given. It is possible that humans who receive a brain wound die from missile-induced apnea instead of brain damage per se. The mortality rate in humans with brain wounding might be reduced by prompt respiratory support. Brain wounding was associated with persistently increased intracranial pressure and reduced cerebral perfusion pressure not entirely attributable to intracranial bleeding. The magnitude of these derangements appeared to be missile energy-dependent and approached dangerous levels in higher-energy wounds. All wounded cats exhibited postwounding increases in blood glucose concentrations consistent with a generalized stress reaction. A transient rise in hematocrit also occurred immediately after wounding. Both of these phenomena could prove deleterious to optimal brain function after injury.

Animals↗
PubMed1988

Pyogenic cervical osteomyelitis presenting as a massive prevertebral abscess in a patient with rheumatoid arthritis.

Pre-existing rheumatoid arthritis appeared to have masked the diagnosis and contributed to a succession of hazardous events in a 58-year-old man with pyogenic cervical osteomyelitis. A massive prevertebral abscess and near asphyxiation finally led to the diagnosis of an indolent Staphylococcus aureus infection in a course marked by antecedent staphylococcal sepsis, a series of dangerous cervical spine chiropractic manipulations in the presence of advanced bony destruction, and, ultimately, cervical spine bony collapse and gibbus formation. The absence of myelopathy despite long-standing progressive advanced destruction is noteworthy. The roentgenologic documentation of this progression was unique. This appears to be the first fully documented case of cervical spine osteomyelitis presenting as a prevertebral abscess in a patient with rheumatoid arthritis.

Abscess↗
PubMed1985

Long-term effects of focal, cortical injuries upon articulation and discrimination performance.

Residual, long-term effects of cortical injuries upon speech production are rarely examined. In this study, we examined the articulation and discrimination abilities in twelve subjects who received focal, cortical injuries in Vietnam during 1968-1971. The subjects were divided into two groups based upon the hemisphere (right or left) of lesion. Data revealed the left-hemisphere injured group produced a greater number of articulation and discrimination errors than the right-hemisphere injured group. Articulation errors occurred more often than discrimination errors in both groups. However, a feature analysis revealed the left-hemisphere injured group made predominantly combination errors and the right-hemisphere injured group made predominantly place errors. Taken overall, the data suggest the left-hemisphere injured group may experience residual difficulties with the encoding of phonological units while the right-hemisphere injured group appears to have residual problems that may be related to the spatial correlates of speech.

Adult↗
PubMed1984

The correlation between surgical and CT estimates of brain damage following missile wounds.

The occurrence of distant brain damage following an apparent focal missile injury to the brain has not been well documented until computerized tomography scanning demonstrated this phenomenon. Mechanisms of additional or distant damage within the brain may include a high deposit of kinetic energy from the penetrating missile, additional vascular damage, and possibly neuronal and axonal degeneration. Widespread and distant brain changes may explain some instances of late neuropsychological and psychiatric dysfunction or rehabilitation failure following a brain wound. Brain imaging should be used to properly evaluate the full extent of brain damage following wounding.

Adult↗
PubMed1982

An analysis of fatal and non-fatal head wounds incurred during combat in Vietnam by U.S. forces.

Analysis of data obtained from U.S. military personnel who received either a lethal or non-lethal brain or head wound in Vietnam indicate that: 1. Bullets caused more fatal brain wounds that did fragments. 2. Most bullet wounds were received at close range, 40.9 m average. Most fatal fragment wounds to the brain occurred at a very close range, 2.9 m average. 3. Clinically significant intracranial blood clots occurred in only 7% of all fatal brain wounds. Only one man with a non fatal brain wound had an associated clot, 3.3%. 4. Helmets offered no protection against bullets but gave significant protection against fragments. 5. Men who sustained either fetal or non fatal brain wounds became immediately militarily non effective.

Brain Injuries↗
PubMed1981

The effect of severe hypoglycemia upon cerebrospinal fluid formation, ventricular iodide clearance, and brain electrolytes in rabbits.

Severe insulin-induced hypoglycemia in rabbits reduces cerebrospinal fluid (CSF) formation, but not ventricular iodide clearance as measured by ventriculocisternal perfusion. This indicates that CSF production is ultimately glucose-dependent but that ventricular iodide clearance is not. The data suggest that severe hypoglycemia results in intracellular potassium loss within the brain and show that extracellular sodium replaces lost intracellular potassium. Hypoglycemia probably results in cellular adenosine triphosphate (ATP) reduction which affects membrane Na/K ATPase and the ability of the brain cell to maintain a potassium gradient. Potassium levels in the CSF also rise consequent to hypoglycemia. Homeostatic mechanisms that maintain a constant CSF potassium, therefore, are also affected by hypoglycemia.

Adenosine Triphosphate↗
PubMed1980

SIADH after subarachnoid hemorrhage and craniotomy.

A 64-year-old woman had the syndrome of inappropriate ADH secretion (SIADH) after surgical repair of a ruptured aneurysm of the anterior communicating artery. SIADH began while the intracranial pressure was elevated, and resolved when the pressure returned to normal. Whether this syndrome was caused by direct hypothalamic lesions, local pressure on the hypothalamus secondary to enlargement of the third ventricle, or some other mechanism cannot be ascertained. The occurrence of intracranial pressure changes with SIADH is described.

Brain↗
PubMed1979

Further data on the acute effect of intravenous steroids on canine CSF secretion and absorption.

Considerable difference of opinion has arisen as to whether intravenously administered steroids affect cerebrospinal fluid (CSF) production in the acute laboratory animal undergoing ventriculocisternal perfusion. Our experiments with ventriculocisternal perfusion in dogs indicate that, when given intravenously, neither dexamethasone, methylprednisolone, hydrocortisone, nor aldosterone result in a significant, acute effect upon CSF production. Similarly, CSF absorption and outflow resistance mechanisms are not acutely affected by intravenous methylprednisolone, hydrocortisone, and aldosterone. Dexamethasone also probably does not produce an immediate effect upon CSF absorption.

Aldosterone↗
PubMed1977

Pancreatitis following spinal cord injury.

Six cases of pancreatitis following spinal cord injury are presented. No single, etiologically accepted mechanism already postulated to cause pancreatitis can account for all the cases reported. The authors hypothesize that spinal cord disruption may produce pacreatitis by sympathetic-parasympathetic nervous system imbalance resulting in over-stimulation of the sphincter of Oddi. This may lead to stasis of secretions with absorption of amylase into the systemic circulation, and structural pancreatic damage. Pancreatitis in those with cord injuries is easily overlooked because abdominal pain is usually absent and fever is usually attributed to more frequently occurring pulmonary or urinary tract infections. Recognition of this complication is important in order to decrease the morbidity and mortality that follows spinal cord damage.

Adult↗