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T R Sadler

Publications and source records attributed to T R Sadler.

At least 19 recordsLinked to original sources
PubMed2005

Mapping cerebral blood flow changes during auditory-cued conditioned fear in the nontethered, nonrestrained rat.

Conditioned fear (CF) is one of the most frequently used behavioral paradigms; however, little work has mapped changes in cerebral perfusion during CF in the rat-the species which has dominated CF research. Adult rats carrying an implanted minipump were exposed to a tone (controls, n = 8) or a tone conditioned in association with footshocks (CS group, n = 9). During reexposure to the tone 24 h later, animals were injected intravenously by remote activation with [14C]-iodoantipyrine using the pump. Significant group differences in regional CBF-related tissue radioactivity (CBF-TR) were determined by region-of-interest analysis of brain autoradiographs, as well as in the reconstructed, three-dimensional brain by statistical parametric mapping (SPM). CS animals demonstrated significantly greater, fear-enhanced increases in CBF-TR in auditory cortex than controls. The lateral amygdala was activated, whereas the basolateral/basomedial and central amygdala were deactivated. In the hippocampus and medial prefrontal cortex, CBF-TR increased significantly ventrally but not dorsally. Significant activations were noted in medial striatum and the thalamic midline and intralaminar nuclei. However, the ventrolateral/dorsolateral striatum and its afferents from motor and somatosensory cortex were deactivated, consistent with the behavioral immobility seen during CF. Significant activations were also noted in the lateral septum, periaqueductal gray, and deep mesencephalic nucleus/tegmental tract. Our results show that auditory stimuli endowed with aversive properties through conditioning result in significant redistribution of cerebral perfusion. SPM is a useful tool in the brain mapping of complex rodent behaviors, in particular the changes in activation patterns in limbic, thalamic, motor, and cortical circuits during CF.

Animals↗
PubMed1989

Solitary plasmacytoma of the sternum: surgical resection with long-term follow-up.

Two patients with solitary plasmacytoma of the sternum were treated with primary surgical resection. Good long-term results were obtained. There is no long-term documentation that primary radiotherapy alone is the treatment of choice for solitary plasmacytomas. An individualized approach is warranted, especially when there is an isolated bulky lesion involving the chest wall.

Aged↗
PubMed1985

Upper dorsal sympathectomy.

Over a 20 year period, 60 patients underwent 76 procedures for upper dorsal sympathectomy, usually with a transaxillary approach but occasionally with an anterior approach. Procedures in male patients and in those that were carried out on the right side were most frequent. There were few simultaneous procedures. The extent of sympathectomy included resection of the lower half of the stellate ganglion through the fourth thoracic ganglion. The results were satisfying for patients with vasospastic disorders and hyperhidrosis and quite acceptable for those with causalgia and vaso-occlusive disorders. Complication rates and the incidence of postoperative Horner's syndrome were low. There were prominent differences in results among the various age groups. In addition, female patients and those with bilateral procedures had less favorable results. Factors that did not appear to affect results included technique of surgical approach, extent of sympathectomy, presence of Horner's syndrome, or the addition of other procedures. Current indications for upper dorsal sympathectomy include cases of Raynaud's and Buerger's diseases refractory to drug therapy, causalgia, vaso-occlusive disorders, and hyperhidrosis.

Adolescent↗
PubMed1982

Technique and value of operative arteriography in coronary artery bypass operations.

In an attempt to make evaluation of coronary artery bypass more meaningful, operative coronary arteriography has been used to aid in defining more precisely the technical aspects of the operation at a time when corrective measures can be carried out. Arteriography is performed following the completion of distal bypass graft anastomoses, whether saphenous vein or internal mammary artery (IMA) bypasses are used. Cut films are exposed at the rate of 2 to 4 frames per second and are evaluated for showing (1) status of anastomosis, (2) status of runoff, (3) lesions undetected preoperatively, and (4) any problems with the bypass conduit. A total of 934 vessels (including 107 IMA grafts) have been visualized in 535 patients. Some form of technical revision was necessary in nine instances. The use of this technique during intraoperative balloon dilatation, in conjunction with and to extend the benefits of conventional bypass, is currently being evaluated.

Angiography↗
PubMed1981

Aneurysm of the descending thoracic aorta: replacement with the use of a shunt or bypass.

The optimal method of protecting the spinal cord and viscera during the resection of aneurysms of the descending thoracic aorta is controversial, and some surgeons have recently abandoned shunting and bypass techniques. We are concerned that this may not be the safest approach in most surgeon's hands and have reviewed our experience with a consecutive series of these aneurysms, all of which were done with either bypass or a shunt. Between 1965 and 1976, we performed 23 aneurysm replacements with femorofemoral bypass. From 1976 to 1980, we used the Gott shunt in 12 aneurysm operations. Atherosclerotic, traumatic, and dissecting aneurysms were all presented. Nineteen operations were elective and 16 were urgent. Three patients died in the hospital, for an 8.6% operative mortality. There were no cases of paraplegia in the entire series of 35 operations. The actuarial 5 year survival rate (including operative deaths) is 79%. We conclude that when the appropriate surgical technique of aneurysm replacement is combined with a shunt or bypass, an acceptable operative mortality and a very low incidence of paraplegia can be obtained.

Aortic Dissection↗
PubMed1979

Dynamic behavior of prosthetic aortic tissue valves as viewed by high-speed cinematography.

Using a valve testing apparatus of our own design and with a high-speed (600 to 800 frames per second) 16 mm movie camera, films were made of Hancock porcine, Carpentier-Edwards porcine, and Ionescu-Shiley bovine pericardial valves mounted in the aortic position and cycled under physiological conditions at 72 to 100 beats per minute. Fresh and explanted valves were observed using saline or 36.5% glycerol as the pumping solution. When fresh valves were studied using saline solution as the pumpint fluid, the Hancock and Carpentier-Edwards porcine valves showed high-frequency leaflet vibration, which increased in frequency with higher cycling rates. Abnormal leaflet motion was decreased when glycerol was used as the blood analogue. The Ionescu-Shiley bovine pericardial valve did not show abnormal leaflet motion under these conditions. Conclusions drawn from tissue valve testing studies that use excessively high pulsing rates and pressures (accelerated testing) and saline or water as pumping solutions cannot be transposed to predict the fate of tissue valves in a clinical setting.

Aortic Valve↗
PubMed1975

Thoracic outlet compression. Application of positional arteriographic and nerve conduction studies.

Positional arteriography has not proved to be of significant assistance in the evaluation of patients with thoracic outlet compression and should be reserved for those patients presenting with an obvious arterial problem such as aneurysm, obstruction, or embolic phenomena. Positional ulnar nerve conduction times were positive in 88 per cent of all patients operated on for thoracic outlet compression. Patients with normal neutral and elevated velocities through the outlet should be approached cautiously from a surgical standpoint. We believe that positional ulnar nerve conduction times are a desirable addition to the diagnostic armamentarium of the physician evaluating the patient presenting with symptoms and signs of the thoracic outlet compression syndrome.

Angiography↗
PubMed1975

In vivo strain measurements of a prosthetic aortic valve.

Up to the present, stress forces on prosthetic heart valves have been studied primarily in an in vitro state and have been derived with a fair amount of estimation. Because of the practical and clinical implications, such as forces that may cause fabric wear or material deterioration, we felt that in vivo determination would be worthy of investigation. A microminiature strain gauge was secured to each leg of a non-cloth-covered prosthetic aortic valve and connected to a dual-beam oscilloscope. Strain measurements were first determined in a pulse duplicator with a blood analogue solution and physiological pressures and flow. The valve was also implanted into a dog in the subcoronary position and strain again measured. In vivo strain was found to be approximately 57 per cent of strain on a prosthetic aortic valve, in vitro, under the conditions of this experiment. This represents the first time that strain and force on a prosthetic aortic valve have been determined directly in the intact animal.

Animals↗