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Biomedical subjects

C B Wright

Publications and source records attributed to C B Wright.

At least 91 records · Page 5Linked to original sources
PubMed1976

Cerebral blood flow determinations by radioactive microspheres in the subhuman primate: influence of unilateral internal carotid ligation, hypercapnic acidosis, and hypocapnic alkalosis.

Cerebral blood flow (CBF) was measured by electromagnetic and radioactive microsphere (RMS) techniques in the anubis baboon. Regional cerebral blood flows were calculated by distribution of intracardiac injections of RMS, labeled with one of three radionuclides: 51Cr, 85Sr, or 141Ce. In Group I (six animals, normocapnia), CBF's as estimated by electromagnetic measurement of internal carotid blood flow, were 65 +/- 10 and 74 +/- 4 (S.E.M.) ml. per minute per 100 Gm. for the right (RH) and left (LH) cerebral hemispheres, respectively; whereas CBF's as estimated by the RMS technique were 65 +/- 5 and 70 +/- 4 ml. per minute per 100 Gm., respectively, and these values were not significantly (p greater than 0.05) different. CBF, as determined by RMS techniques in Group 1, was not altered by unilateral internal carotid arterial ligation. In Group 2 (seven animals), arterial PCO2 was varied randomly from a low range (18 +/- 2 mm. Hg, L), to a middle range (PCO2 36 +/- 2, M), and a high range (PCO2 64 +/- 2, H), and CBF was measured by the RMS technique. During L, M, and H, CBF's were 44 +/- 10, 75 +/- 15, and 159 +/- 27 ml. per minute per 100 Gm., respectively, for RH, whereas CBF's were 44 +/- 10, 75 +/- 15, and 160 +/- 26 ml. per minute per 100 Gm., respectively, for LH. During H, RH and LH were significantly (p less than 0.05) greater than during L and M. Changes in regional CBF were uniform throughout the brain. These data demonstrate the correlation between CBF, as estimated by electromagnetic and RMS techniques, as well as confirm the adequacy of collateral cerebral circulation during unilateral carotid arterial ligation in the baboon. The usefulness of the RMS technique for hemispheric and regional CBF measurements is prevented also.

Acidosis, Respiratory↗
PubMed1976

Hemodynamic effects of intra-arterial injection of drugs of abuse.

Acute vascular insufficiency following intra-arterial injection of a variety of drugs has been recognized for many years. The present study addresses the hypothesis that this vascular insufficiency may be due to vasospasm. Intra-arterial injections of logarithmic doses of drugs of abuse from the barbiturate, narcotic, non-narcotic analgesic, and amphetamine groups were studied in baboons. All drugs except amphetamine produced significant increases in femoral flow. Dextroamphetamine produced insignificant alteration in flow. Solid excipients, cornstarch, and talcum powder when injected intra-arterially decreased flow, and vascular obstruction was shown angiographically. These data suggest that vasospasm is not a primary response of intra-arterial injection of drugs of abuse.

Animals↗
PubMed1975

Prediction of intestinal viability using Doppler ultrasound technics.

The determination of intestinal viability intraoperatively remains difficult. Intestinal blood flow can be demonstrated in the serosa and mesentery-bowel junction by use of the Doppler ultrasound flow detector. The presence of flow in these areas after an ischemic episode correlates well with ultimate viability of the intestine. This technic may be useful clinically to assist in determining viability and the limits of resection of previously ischemic intestine.

Animals↗
PubMed1975

Electronic particle size measurements of platelet aggregates formed in vitro.

The aggregation of human platelets induced by adenosine diphosphate (ADP) was used to evaluate electronic particle size analyzer measurements of platelet aggregates in plasma. As platelets began to clump in plasma, the total volume and the diameter of individual aggregates increased; after a time dependent on experimental conditions, the diameter increased but the total volume remained unchanged. Similar but opposite changes in size distribution occurred during platelet deaggregation. The total volume of aggregates formed in plasma varied (linear correlation coefficient = 0.99) with the total volume of platelets which were available to clump and with simultaneous changes in optical density. The diameter of the aggregates varied with the concentration of, and time of exposure to, ADP and with the total volume of platelets and aggregates in plasma was not different from that of control platelets in untreated plasma, the individual platelets aggregated without an accompanying increase in size. This study demonstrates that platelet aggregation can be characterized by electronic measurements of the size distribution of platelet aggregates.

Adenosine Diphosphate↗
PubMed1975

Decreased oxygen uptake with stored blood in the isolated hindlimb.

Storage of red cells in acid-citrate-dextrose (ACD) solution for more than a week has been shown to cause a reduction in red cell 2,3-diphosphoglycerate (2,3-DPG), resulting in a decrease in the half-saturation pressure (P50) of stored blood, thus increasing hemoglobin-oxygen affinity and theoretically decreasing oxygen delivery to the tissues. A method to isolate and perfuse the hindlimb in a dog has been developed and used successfully to compare the difference of oxygen release between banked and fresh ACD blood. Ten dogs were perfused using canine blood collected in standard blood transfusion bags containing ACD and stored at 4 degrees C and fresh blood collected in a similar manner but used immediately. The total oxygen release in the limb during perfusion with fresh blood was significantly greater than during perfusion with stored blood.

Animals↗
PubMed1975

Operative assessment of carotid endarterectomy: Internal carotid arterial back pressure, carotid arterial blood flow, and carotid arteriography.

Determination of ICA back pressure, electromagnetic measurement of internal carotid arterial blood flow, and performance of operative carotid arteriography have been assessed in a series of elective carotid endarterectomies. If ICA back pressure is used to determine the need for an internal shunt, our data suggest that a minimal pressure of 60-70 mmHg is required to insure adequacy of collateral cerebral blood flow in all patients. Internal carotid arterial blood flow was not significantly increased after endarterectomy. Although flow measurements are of some interest, their routine measurement does not appear to have significant clinical usefulness. Operative carotid arteriography is a valuable technique in identifying unsuspected technical errors at the site of endarterectomy and should be used routinely.

Aged↗
PubMed1975

Microaggregate formation during regional hypoperfusion.

Occlusion of the infrarenal aorta in the dog is associated with formation of microaggregates. Etiologic factors involve stasis, acidosis and hypoperfusion. Upon restoration of flow, microaggregates are transported through the inferior vena cava to the pulmonary circulation as microemboli. The volume of microaggregates appearing in the inferior vena cava after restoration of flow in our experiments is small and seems inadequate to cause significant pulmonary mechanical obstruction. The vasoactivity of these microparticles, although to date unknown, may be significant in the etiology of the pulmonary alterations which were described previously.

Animals↗
PubMed1975

The filtration limitations of ultrapore filters.

The filtration effectiveness of four commercially available microaggregate filters was determined using 14-day-old stored human blood in a constant infusion system. All filters significantly reduced the volumes of microaggregates contained in 500 ml. of blood. Three of the filters tested either occluded or failed to effectively remove microdebris from larger volumes of blood. These filters should be employed only for single blood transfusions. A fourth filter--of grid design--was effective in removing microdebris from 2,000 ml. of blood, the limits of the study. When employing microaggregate filters in massive transfusion situations for the prevention of pulmonary dysfunction, filtration characteristics and efficiencies of the filters employed must be known so that inadvertent administration of microdebris to the patient might be prevented.

Animals↗
PubMed1975

Evaluation of blood filters: dynamics of platelets and platelet aggregates.

Microaggregates of platelets have been found in stored blood and in extracorporeal circulation systems and the potential microembolism of these particles intensely studied. Four currently available filters were studied for their filtration effectiveness of induced platelet microaggregates and for the removal of normal platelets from blood collected in acid citrate dextrose or heparin. Dacron wool filtration significantly (P less than 0.001) reduced aggregates in 13 to 80 mu sizes to a level similar to that in normal blood. In general, as filtration effectiveness increased so did the elimination of normal platelets.

Animals↗
PubMed1975

Adrenergic mechanisms in the cephalic and cerebral circulations of the subhuman primate.

Effects of circulating adrenergic amines on the cerebral circulation remain contraversial. Common carotid (CCF) and internal carotid (ICF) arterial flows were determined electromagnetically in eight lightly anesthetized baboons to evaluate alterations in the cephalic and cerebral vascular beds, respectively. Epinephrine (E), norepinephrine (NE), phenylephrine (PE), and isoproterenol (I) were injected randomly in doses of 10-3, 10-2, 10-1, and 1 mug (base) per kilogram into each carotid artery. Measurements were repeated in four animals after alpha-adrenergic blockade with phenoxybenzamine and in another four animals after beta-adrenergic blockade with propranolol. Baseline CCF was 75 plus or minus 10 (S.E.M.) ml. per minute and ICF was 58 plus or minus 8 ml. per minute. Significant (p smaller than 0.05) CCF changes without arterial pressure alterations occurred with 10-1 mug per kilogram doses. Alpha blockade significantly (p smaller than 0.05) attenuated the effects of E, NE, and PE on CCF while beta blockade significantly (p smaller than 0.05) attenuated the effect of I on CCF. ICF did not change significantly (p greater than 0.05) after injection of any of the vasoactive amines, unless associated with pressure changes at the highest dose. Our data suggest the presence of alpha- and beta-adrenergic receptor sites within the cephalic circulation resulting in significant flow responses to intra-arterial adrenergic amines. The absence of responses in the cerebral circulation suggests that circulating catecholamines do not significantly influence or regulate the cerebral vasculature. In addition the data suggest that use of adrenergic agonists to alter the hemodynamics of the cerebral circulation is limited.

Adrenergic Agonists↗