Robert W. Ogilvie

Basic Fibroblast Growth Factor Increases Collateral Blood Flow in Rats With Femoral Arterial Ligation

The potential for exogenous infusion of basic fibroblast growth factor (bFGF) to increase collateral blood flow to dependent tissue was quantified in adult male rats with peripheral arterial insufficiency. Occlusion of the femoral artery at a proximal site did not infringe on resting blood flow to the distal hindlimb muscle, but did remove the blood flow reserve. Blood flow to the hindlimb muscles was measured with radiolabeled microspheres using an isolated hindlimb preparation perfused in the descending aorta (Krebs-Henseleit bicarbonate, 5% albumin medium containing red blood cells [40% hematocrit]) at 100 mm Hg. Calf muscle blood flow changed modestly (approximately equal to 50%) with infusion of only the carrier (heparin/saline), increased markedly over the first 2 weeks of bFGF infusion (1 microgram/d into the femoral artery), but did not change further with infusion for 4 weeks. Waiting 2 weeks after 1 week of bFGF infusion did not further increase the intermediate improvement in blood flow. The improved collateral blood flow and increased muscle capillary density likely contributed to the enhanced muscle performance observed during nerve stimulation in situ. X-ray films of arterial casts identified an expansion of upper thigh vessels that likely served as collaterals. In animals with peripheral arterial insufficiency, short-term exogenous infusion of bFGF is effective at inducing vascular expansion that is sufficient to improve the flow reserve of dependent distal tissue and enhance muscle function. This raises the expectation that a similar response in patients with peripheral arterial insufficiency would significantly improve morbidity, including the symptoms of intermittent claudication.

Students’ attitudes towards computer testing in a basic science course

The introduction of computerized testing offers several advantages for test administration, however, little research has examined students’ attitudes toward computerized testing. This paper, reports the attitudes of 202 students in a first year cell biology and histology course toward computerized testing and its influence on their study habits over a three year period.

Heparin Increases Exercise-Induced Collateral Blood Flow in Rats With Femoral Artery Ligation

The potential for heparin to enhance the training-induced increase in collateral-dependent blood flow to the distal hind-limb muscles was evaluated after bilateral femoral artery ligation in adult male rats (approximately 350 g). Rats received either saline (n = 34) or heparin (n = 36) injections and were kept sedentary (limited to cage activity) or exercised on a treadmill 5 days per week up a 15% incline by one of two protocols: (1) exercise at a constant moderate speed (20 m/min) for approximately 6 wks or (2) exercise at a progressively increased speed for 7 to 8 weeks (started at 20 m/min, increased at 15 minutes to 25 m/min, and then increased at 30 minutes to 30 m/min). Heparin- and saline-treated rats, exercised by the moderate-speed protocol, were run for the same time each day. Collateral-dependent blood flow to the distal limb tissue was determined by using 15-microns 85Sr-labeled microspheres in an isolated hindquarter preparation perfused in the descending aorta at 100 mm Hg. For comparison with the above groups, sedentary animals with acute femoral artery ligation and without femoral obstruction were included. Exercise tolerance increased from approximately 7 minutes initially to 30 to 40 minutes per bout; tolerance was greater in the heparin-injected rats than in the saline-injected rats (P < .05). Muscle performance of the gastrocnemius-plantaris-soleus muscle group (GPS) during isometric contractions in situ improved with training, was further increased by heparin administration (P < .001), and generally scaled with recovery of blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise training enhances basic fibroblast growth factor-induced collateral blood flow

This study evaluated whether daily exercise would enhance the peripheral collateral vessel development found in response to exogenous basic fibroblast growth factor (bFGF) infusion. After bilateral femoral occlusion, male Sprague-Dawley rats (∼325 g) received intra-arterial infusions of either bFGF (1 μg/day; n = 15) or carrier solution ( n = 13) via osmotic pumps for 2 wk. Subgroups of each treatment were kept sedentary (cage activity) or trained by walking at 20 m/min at 15% grade, two times a day, 5 days/wk for 4 wk. Training markedly increased citrate synthase activity in the active muscle ( P < 0.001). Muscle function and blood flows (85Sr microsphere) were evaluated using an isolated hindquarter perfused at 100 mmHg via the abdominal aorta. The significant increase in blood flow to the entire hindlimb in the sedentary animals, caused by bFGF infusion ( P < 0.05), was further increased ( P < 0.01) in the bFGF-trained group. The quantitatively largest increases in blood flows were observed in the collateral-dependent tissues of the distal hindlimb. Blood flows to the entire calf muscle group increased ∼140% in carrier-trained ( P < 0.001), ∼180% in bFGF sedentary ( P< 0.001), and ∼240% in the bFGF-trained ( P < 0.001) groups compared with the carrier sedentary group. The increases in collateral blood flow were functionally important, as improvements in calf muscle performance correlated with measured blood flows. Our results demonstrate that exogenous bFGF administration in combination with a moderate-intensity exercise program greatly increases collateral-dependent blood flow and improves muscle performance. That physical activity enriched the bFGF response is consistent with the hypothesis that hemodynamic factors are important contributors to collateral vessel enlargement.This study evaluated whether daily exercise would enhance the peripheral collateral vessel development found in response to exogenous basic fibroblast growth factor (bFGF) infusion. After bilateral femoral occlusion, male Sprague-Dawley rats (approximately 325 g) received intra-arterial infusions of either bFGF (1 microg/day; n = 15) or carrier solution (n = 13) via osmotic pumps for 2 wk. Subgroups of each treatment were kept sedentary (cage activity) or trained by walking at 20 m/min at 15% grade, two times a day, 5 days/wk for 4 wk. Training markedly increased citrate synthase activity in the active muscle (P < 0.001). Muscle function and blood flows (85Sr microsphere) were evaluated using an isolated hindquarter perfused at 100 mmHg via the abdominal aorta. The significant increase in blood flow to the entire hindlimb in the sedentary animals, caused by bFGF infusion (P < 0.05), was further increased (P < 0.01) in the bFGF-trained group. The quantitatively largest increases in blood flows were observed in the collateral-dependent tissues of the distal hindlimb. Blood flows to the entire calf muscle group increased approximately 140% in carrier-trained (P < 0.001), approximately 180% in bFGF sedentary (P < 0.001), and approximately 240% in the bFGF-trained (P < 0.001) groups compared with the carrier sedentary group. The increases in collateral blood flow were functionally important, as improvements in calf muscle performance correlated with measured blood flows. Our results demonstrate that exogenous bFGF administration in combination with a moderate-intensity exercise program greatly increases collateral-dependent blood flow and improves muscle performance. That physical activity enriched the bFGF response is consistent with the hypothesis that hemodynamic factors are important contributors to collateral vessel enlargement.

Oxygen tension in the globus pallidus and neostriatum of unanesthetized rats during exposure to hyperbaric oxygen

Abstract Unanesthetized rats were exposed 1 h to 100% oxygen at 60 psig (5 atmospheres absolute). Utilizing platinum semimicroelectrodes, oxygen tension was recorded from the globus pallidus and the neostriatum. Oxygen tension increased from control values (room air at ambient pressure) during the exposure period in both experimental groups. In the globus pallidus, oxygen tension reached the first stable peak in an average of 27.8 min, whereas in the neostriatum the first stable peak was reached in an average of 3.0 min. The results of this study suggest a correlation between oxygen tension and pathologic changes observed in the basal ganglia.

E-education in pathology including certification of e-institutions

E–education or electronically transferred continuous education in pathology is one major application of virtual microscopy. The basic conditions and properties of acoustic and visual information transfer, of teaching and learning processes, as well as of knowledge and competence, influence its implementation to a high degree. Educational programs and structures can be judged by access to the basic conditions, by description of the teaching resources, methods, and its program, as well as by identification of competences, and development of an appropriate evaluation system. Classic teaching and learning methods present a constant, usually non-reversible information flow. They are subject to personal circumstances of both teacher and student. The methods of information presentation need to be distinguished between static and dynamic, between acoustic and visual ones. Electronic tools in education include local manually assisted tools (language assistants, computer-assisted design, etc.), local passive tools (slides, movies, sounds, music), open access tools (internet), and specific tools such as Webinars. From the medical point of view information content can be divided into constant (gross and microscopic anatomy) and variable (disease related) items. Most open access available medical courses teach constant information such as anatomy or physiology. Mandatory teaching resources are image archives with user–controlled navigation and labelling, student–oriented user manuals, discussion forums, and expert consultation. A classic undergraduate electronic educational system is WebMic which presents with histology lectures. An example designed for postgraduate teaching is the digital lung pathology system. It includes a description of diagnostic and therapeutic features of 60 rare and common lung diseases, partly in multimedia presentation. Combining multimedia features with the organization structures of a virtual pathology institution will result in a virtual pathology education institution (VPEI), which can develop to a partly automated distant learning faculty in medicine.

Oxygen Tensions in the Deep Gray Matter of Rats Exposed to Hyperbaric Oxygen

Selective necrosis of neurons and nuclei consistently occurs within the central nervous system (CNS) of rats paralyzed by repeated 1 hour exposures to 5 atmospheres of oxygen.l The distribution of the lesions differs from those of hypoxia in the same animal species. Excessive oxygen inhibits many enzymes vital to cellular metabolism in the CNS and it is reasonable to hypothesize that the neuronal necrosis produced by hyperbaric oxygen exposure is related to elevated tissue oxygen tensions. However, hyperbaric oxygen notedly produces cerebral vasospasm and a reduction in cerebral blood flow, and regional ischemia has been a tenable hypothesis for the occurrence of the CNS lesions. This latter mechanism seems unlikely because unilateral carotid artery ligation protects the ipsilateral but not the contralateral cerebral hemisphere from the occurrence of the oxygen induced lesions.2 (see Fig. 1)Selective necrosis of neurons and nuclei consistently occurs within the central nervous system (CNS) of rats paralyzed by repeated 1 hour exposures to 5 atmospheres of oxygen.l The distribution of the lesions differs from those of hypoxia in the same animal species. Excessive oxygen inhibits many enzymes vital to cellular metabolism in the CNS and it is reasonable to hypothesize that the neuronal necrosis produced by hyperbaric oxygen exposure is related to elevated tissue oxygen tensions. However, hyperbaric oxygen notedly produces cerebral vasospasm and a reduction in cerebral blood flow, and regional ischemia has been a tenable hypothesis for the occurrence of the CNS lesions. This latter mechanism seems unlikely because unilateral carotid artery ligation protects the ipsilateral but not the contralateral cerebral hemisphere from the occurrence of the oxygen induced lesions.2 (see Fig. 1)

Effects of hyperbaric oxygenation on electrical activity of globus pallidus and neostriatum

Abstract The electrical activity (electroencephalogram, EEG) and oxygen tension of the globus pallidus and neostriatum were studied in anesthetized rats under hyperbaric oxygenation (100% oxygen at 5 atm absolute). An increase in oxygen tension was correlated with an increase in electrical activity in the globus pallidus. The changes in oxygen tension and EEG of the neostriatum did not appear to be significant. Exposure to a hyperoxic environment produced an initial desynchronization of the EEG which was observed in only the globus pallidus. The results of this study suggest a correlation between oxygen tension, electrical activity, and pathological changes observed in selected subcortical nuclei.

Comparison of Oxygen Tension in the Spinal Cord and Globus Pallidus During Hyperbaric Oxygen Exposure of Rats Under Pentobarbital Anesthesia

Lesions in the brain and spinal cord have been produced by exposing rats to hyperbaric oxygen. Complete or partial necrosis of nuclear groups with damage to myelin, axons and glia have been produced consistently in the globus pallidus and spinal cord gray matter of unanesthetized rats after intermittent exposures to 100% oxygen at 60 P.S.I.G. (Pounds per Square Inch by the Guage).1,2 Pentobarbital anesthesia has been found to protect the globus pallidus from the necrotic lesions of hyperbaric oxygen, but it potentiates lesions of the spinal cord.3 In exploration of the causal mechanism of these lesions, we have previously reported direct measurements of oxygen tensions in the globus pallidus of rats anesthetized with pentobarbital and compressed to 60 P.S.I.G. with 100% oxygen.4 Oxygen tensions up to 475 mmHg were recorded within five minutes after achieving a pressure of 60 P.S.I.G. The oxygen tensions then fell to an average value of 60 mmHg within 45 minutes.