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Biomedical subjects

J A Barrett

Publications and source records attributed to J A Barrett.

At least 91 records · Page 5Linked to original sources
PubMed1987

The pathways mediating affective defense and quiet biting attack behavior from the midbrain central gray of the cat: an autoradiographic study.

The purpose of this study was to describe the pathways which mediate feline affective defense and quiet biting attack behavior elicited from the midbrain central gray. In these experiments, methods of [3H]leucine and 2-deoxy-[14C]glucose (2-DG) radioautography were utilized in concert with the technique of electrical and chemical brain stimulation. Affective defense behavior elicited from the midbrain central gray is characterized by marked vocalization such as hissing and growling, pupillary dilatation, urination and piloerection. In contrast, quiet biting attack elicited from the midbrain central gray lacks overt autonomic signs observed with affective defense response as well as the stalking component which is typically associated with stimulation of the lateral hypothalamus. Nevertheless, central gray-elicited attack resulted in a directed bite of the neck of an anesthetized rat in a manner similar to that observed from the hypothalamus. Affective defense was elicited from the dorsal half of the midbrain central gray, while quiet biting attack was obtained following stimulation of the ventral half of the midbrain central gray, thus indicating a functional differentiation of the central gray with respect to these two forms of aggression. In a separate series of experiments, affective defense or quiet biting attack response was identified by electrical stimulation through a cannula electrode situated in the midbrain central gray. The affective defense responses were subsequently elicited following microinjections of D,L-homocysteic acid through the same cannula electrode in order to demonstrate that these responses were the result of direct stimulation of cell bodies within the central gray. Then, one of the following autoradiographic tracing procedures was utilized: (1) [3H]leucine was injected through a cannula electrode and the animal was sacrificed after a 4- to 14-day survival period; or (2) a 2-DG solution was systemically injected and electrical stimulation was applied through the cannula electrode in order to metabolically activate the pathways associated with each of these responses. In general, the pattern of labelled target regions as indicated by 3H-amino acid radioautography was similar to that obtained from the 2-DG autoradiographic analysis. The principal ascending pathway associated with affective defense was traced to the anteromedial hypothalamus and medial thalamus. Concerning descending projections, label was traced into the central tegmental fields of the midbrain and pons, locus coeruleus and motor and main sensory nuclei of the trigeminal complex.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1987

The effects of intrahypothalamic injections of norepinephrine upon affective defense behavior in the cat.

The effects of norepinephrine microinjected into the anterior hypothalamus were examined in feline affective defense behavior elicited by electrical stimulation of the region of the ventromedial nucleus. Anterior hypothalamic sites from which affective defense behavior could also be elicited by electrical stimulation and which are known to receive inputs from both the ventromedial nucleus and brainstem noradrenergic neurons were selected for pharmacological analysis. Intracerebral injections of 250 ng (1 nM) and 500 ng (2 nM) quantities of norepinephrine placed into the anterior hypothalamus resulted in a significant lowering of the attack thresholds. These reductions in response thresholds which were reversed by either pre- or post-treatment with yohimbine, indicate that the noradrenergic system may play an important role in the regulation of affective defense behavior.

Aggression↗
PubMed1987

Mandatory vs selective exploration for penetrating neck trauma. A prospective assessment.

To determine the optimal management of patients with penetrating wounds to zone II of the neck, we performed a prospective evaluation of 120 consecutive patients with such injuries, correlating the results of clinical and diagnostic examinations with operative findings. Seven patients presenting with life-threatening hemorrhage from the neck wound were operated on immediately; the remaining 113 patients underwent arteriography, laryngotracheoscopy, esophagoscopy, and esophagography, followed by neck exploration. Forty-eight major injuries were identified in 35 neck explorations. Five patients were identified with clinical and diagnostic findings that were considered normal preoperatively; however, at operation six major injuries were found in these patients. This study indicates that potentially lethal injuries to major vascular and visceral structures in the neck may go undetected if selective exploration criteria are used in the decision to explore penetrating wounds to zone II of the neck.

Adolescent↗
PubMed1987

A new method of rapid fluid resuscitation during thoracotomy performed in the emergency room.

A new technique for inserting and securing large bore intravenous lines directly into the right atrium, to be used in patients requiring a thoracotomy in the emergency room, is described herein. A plastic clip is attached to the edge of the atrial appendage and holds a large catheter in place. We have used this new technique successfully at the Cook County Hospital Trauma Unit and have encountered no complications to date.

Catheters, Indwelling↗
PubMed1986

Results of venous reconstruction after civilian vascular trauma.

The treatment of venous injuries remains controversial. In an attempt to evaluate the results of current management of venous injuries, we retrospectively reviewed our experience between 1979 and 1984. During this period 142 patients had sustained injuries to 158 veins in the neck (31 patients), abdomen (45 patients), upper extremity (20 patients), and lower extremity (62 patients). Overall, 90 venous injuries (61%) were repaired, including 83% of caval and iliac vein injuries and 90% of injuries to the common femoral, superficial femoral, and popliteal veins. There was no morbidity after repair of 73 major veins. Morbidity occurred in four of 11 patients after ligation of major veins (edema in two patients and above-knee amputation in two others). Both ligation (N = 51) and repair (N = 17) of lesser veins (jugular, brachial, profunda femoral, tibial, and minor abdominal veins) resulted in no morbidity. Overall mortality was 6% with all deaths occurring in patients with abdominal venous trauma. These data indicate that repair of venous injuries can be performed without morbidity and that minor veins can be ligated without adverse sequelae. However, in view of the morbidity associated with ligation of major veins, efforts to restore flow to these injured vessels appear appropriate unless contraindicated by life-threatening injury.

Adolescent↗
PubMed1986

Measurement of oxygen tension in the ischemic myocardium using encased polargraphic oxygen electrodes.

The ability to continuously monitor the delicate balance between blood flow and oxygen consumption would be a great asset in the study of myocardial ischemia. The present study was performed, in anesthetized dogs, to validate the use of encased polargraphic oxygen electrodes in the study of myocardial ischemia. Polargraphic oxygen electrodes were placed in the area to be rendered ischemic at fixed tissue depths of 3 mm (epicardium) and 9 mm (endocardium). Endocardial and epicardial oxygen tensions as well as the ratio of endocardial to epicardial oxygen tension and left circumflex coronary flow were monitored. Ischemia was induced by decreasing left circumflex coronary flow by 50%. Upon completion of a 20-min poststenotic period, endocardial pO2, endocardial/epicardial ratio, and coronary flow were significantly decreased (59 +/- 7, 52 +/- 7, and 55 +/- 4%, respectively) whereas epicardial pO2 was slightly decreased. Nitroglycerin (10 micrograms/kg, i.v.) markedly increased endocardial pO2 and endocardial/epicardial ratio above poststenotic control (13 +/- 5 mmHg and 64 +/- 10%, respectively) whereas epicardial pO2 was not significantly decreased. The increases in endocardial pO2 occurred at a point where coronary flow and mean arterial pressure were not significantly changed. Conversely, dipyridamole (125 micrograms/kg, i.v.) significantly increased coronary flow (26 +/- 2 ml/min/100 g) although it did not appreciably alter endocardial or epicardial pO2. It is concluded that encased polargraphic oxygen electrodes provide a quantitative method for determination of oxygen tension in the ischemic myocardium.

Animals↗
PubMed1986

Effects of celiprolol in anesthetized dogs with reduced myocardial function.

Celiprolol HCl is a new cardioselective beta adrenoceptor antagonist with both mild propranolol-sensitive partial agonist activity and propranolol-insensitive cardiostimulatory properties. The purpose of the present investigation was to assess the significance of this unique pharmacological profile in a study of the effects of celiprolol in anesthetized dogs with depressed myocardial function. Dogs were acutely instrumented to directly monitor myocardial contractile force (CF), arterial pressure (AP), heart rate (HR), and ECG limb lead II. Mecamylamine 1 mg/kg i.v., and verapamil, 0.5 mg/kg i.v., reduced CF (80 +/- 6 g), HR (76 +/- 4 beats/min), and AP (59 +/- 8 mm Hg). Celiprolol (3 mg/kg i.v.) did not produce any further decrement in myocardial function. There were no appreciable ECG changes. These data suggest that celiprolol may be the drug of choice in patients receiving verapamil, since it should not further compromise myocardial function.

Animals↗
PubMed1986

Fibronectin depletion and microaggregate clearance following trauma.

Ninety-seven traumatized patients had blood samples taken immediately upon admission before any resuscitation. Microaggregate (MA) formation was measured by the screen filtration pressure (SFP) technique. Plasma fibronectin levels (Fn) were measured by immunoturbimetric assay. An Injury Severity Score (ISS) was calculated for each patient. The results show a highly significant correlation between severity of trauma, amount of MA formation, and amount of Fn depletion. We conclude that the highly significant correlation between MA formation and Fn depletion following trauma suggests a role for the reticuloendothelial system (RES) in the clearance of MA that form following trauma. Further, enhancement of RES clearance of MA may be possible by purified Fn or cryoprecipitate administration early in the treatment of trauma patients, thereby preventing the adverse sequelae of end organ MA deposition.

Animals↗
PubMed1986

Effects of nitroglycerin, dipyridamole, nifedipine, verapamil and diltiazem on canine coronary arterial rings contracted with 5-hydroxytryptamine and anoxia.

Anoxia has been shown to potentiate the constrictor effects of 5-hydroxytryptamine (5HT) in isolated vascular tissue. In the present study, canine coronary arterial rings were incubated with various treatments and exposed to 5HT (4 X 10(-7) M) and anoxia (95% N2 and 5% CO2). Developed tension was increased by 250 +/- 40 mg by 5HT alone and 2,000 +/- 90 mg by 5HT and anoxia. Calcium (5 mM) potentiated, while inorganic (lanthanum, 10(-2) M) and organic calcium antagonists (nifedipine, verapamil and diltiazem; IC50 = 7 X 10(-9), 7.3 X 10(-8) and 2.4 X 10(-7) M, respectively) blocked the anoxic potentiation. Anoxia alone decreased resting tension (RT). Methysergide 3 X 10(-5) M inhibited both the 5HT- and anoxia-potentiated responses. Nitroglycerin decreased RT and inhibited the anoxic response (IC50 = 7.6 X 10(-6) M), while dipyridamole decreased RT and did not affect the anoxic response. These data suggest that the potentiation of 5HT contraction by anoxia is dependent upon extracellular calcium influx and is linked to a 5HT receptor. In addition, inhibition of the anoxic response can be achieved at other sites and is not a property common to all coronary vasodilators.

Animals↗
PubMed1986

Celiprolol, a compound possessing weak alpha 2-adrenergic antagonist properties in the dog.

Studies were conducted to evaluate the effects of celiprolol on alpha-adrenergic stimulation of dog saphenous vein rings (postsynaptic effect) and on catecholamine outflow from the dog coronary circulation during sympathetic nerve stimulation in vivo (presynaptic effect). In venous rings, celiprolol, 10(-6) to 10(-4) M, shifted the concentration-response curve to BHT 920 in a concentration-related manner, but had no effect on the response to methoxamine at concentrations less than 10(-4) M. During continuous stimulation of the right stellate ganglion, celiprolol, 1-10 mg/kg i.v., increased the catecholamine concentration in the coronary sinus, while decreasing heart rate. In contrast, propranolol did not affect catecholamine concentration but decreased heart rate, rauwolscine increased both catecholamine concentration and heart rate, and clonidine decreased both catecholamine concentration and heart rate. These results are consistent with the hypothesis that celiprolol possesses weak alpha 2-antagonist properties in addition to its beta 1-blocking activity.

Adrenergic alpha-Agonists↗
PubMed1985

Use of peritoneal lavage to evaluate abdominal penetration.

A retrospective study was undertaken to evaluate peritoneal lavage in detecting abdominal penetration. Two hundred thirty-five patients with thoracoabdominal, flank, or tangential abdominal gunshot wounds were lavaged. Of these patients, 44 (18.7%) had positive lavages, defined as red blood cell counts greater than 10,000 cells/mm3, white blood cell counts greater than 500 cells/mm3, or the presence of bile, feces, or vegetable matter. There were 13.6% false positives and 1.0% false negatives, with an overall accuracy of 96.6%. The results were unaffected by mechanism or site of injury. If the criteria were changed to include red blood cell counts greater than 100,000 cells/mm3, there would have been no false positives, but an unacceptably high 11.1% false negative rate. Therefore we conclude that peritoneal lavage can be a reliable indicator of abdominal penetration provided sufficiently sensitive criteria are used. These criteria should include red blood cell counts greater than 10,000 cells/mm3 instead of 100,000 cells/mm3.

Abdominal Injuries↗
PubMed1984

Breast cancer in mothers given diethylstilbestrol in pregnancy.

We compared the incidence of breast cancer in 3033 women who had taken diethylstilbestrol (DES) in pregnancy during the period from 1940 to 1960 with the incidence in a comparable group of unexposed parous women. We ascertained vital status in 95 per cent of the exposed women and in 93 per cent of the unexposed women and received completed questionnaires for 88 and 85 per cent, respectively. With over 85,000 woman-years of follow-up in each group, the incidence of breast cancer per 100,000 woman-years was 134 in the exposed group and 93 in the unexposed group, yielding a crude relative risk of 1.4 (95 per cent confidence interval, 1.1 to 1.9). The elevated incidence did not appear to be due to bias or to confounding by other risk factors measured in the study. Breast-cancer mortality was slightly higher in the exposed women (relative risk, 1.1) but not significantly so (95 per cent confidence interval, 0.7 to 2.0). We conclude that the incidence of breast cancer is moderately increased in women given DES, but we cannot exclude the possibility that some unrecognized concomitant of DES exposure accounts for this increase.

Actuarial Analysis↗
PubMed1982

Amebic liver abscess.

Amebic liver abscess was seen in 35 patients over a ten-year period at Cook County and the University of Illinois hospitals, Chicago; 32 had immigrated from an area of endemic amebiasis, but three were natives of Chicago. Typically they had right upper-quadrant abdominal pain and fever of short duration (nine days); on physical examination, upper abdominal tenderness and hepatomegaly were usually present. The diagnosis was confirmed by liver scan, serologic studies, aspiration of "anchovy paste" from the abscess, and/or a favorable response to specific antiamebic therapy. Most were solitary abscesses in the right lobe of the liver. Metronidazole treatment alone was adequate in 24 of 29 patients (83%). Nine patients underwent percutaneous or surgical drainage of the abscess owing to incorrect diagnosis (three), persistent pain and fever after medical treatment (three), expanding left lobe abscess (two), and for diagnosis (one). Mortality was 5.7% (two patients). Owing to current immigration patterns amebic liver abscess should be considered in the differential diagnosis of patients with right upper-quadrant pain and fever. The diagnosis should be confirmed with a liver scan and serologic study for amebiasis.

Adolescent↗