Jimmie L. Valentine

The study of the effect of human chorionic gonadotrophic (HCG) hormone on the survival of adrenal medulla transplant in brain Preliminary study

SummaryAutologous adrenal cortex was completely dissected off the medula using microdissection. The adrenal medulla tissue was transplanted to the lateral ventricle in twenty-one adult rats. Group A consisting of ten animals received 200 units of HCG per 100 gram body weight daily for one week and then on every alternate day for seven weeks. The remaining rats (group B) served as control. After eight weeks the brains were removed and a volumetric study was done using histological sections. High pressure liquid chromatography (HPLC) with electrochemical detection for catecholamine assay of the graft was also undertaken. The graft survival in group A was significantly higher (p<0.005) than group B. The level of norepinephrine was significantly higher in group A while dopamine was higher in group B. The higher volume of graft tissue in group A suggests that HCG may help in increased survival and growth of the transplanted tissue. Higher levels of norepinephrine in group A would suggest a tendency for such grafts to be active to a greater extent with the treatment of HCG.

Electromagnetic field focusing (EFF) probe in aneurysm thrombosis

SummaryDue to its capability of producing a well localized intense heat field of predictable dimensions, the electromagnetic field focusing probe was evaluated experimentally as a surgical tool in aneurysm thrombosis. Aneurysm models were created by anastomosing a segment of vein to the abdominal aorta. Seventy-five such aneurysms were created in seventy-five animals. The aneurysms were then placed under the solenoidal radiofrequency coil and the tip of the field focusing probe was inserted into them. Intense heat was delivered with well defined, effective and quick thrombosis and shrinkage of the aneurysm. Nineteen of the aneurysms were followed for up to one week. Histological studies were conducted showing complete thrombosis of the aneurysm with good preservation of the aorta. With further refinement of this technique, it is hoped that stereotaxic aneurysm thrombosis might be possible.

Electromagnetic field focusing (EFF) probe—a new neurosurgical tool

SummaryThe electromagnetic field focusing (EFF) probe is capable of producing well circumscribed, intense heat at the point of contact with the tissue. Experimental studies were carried out to assess this probe as a neurosurgical tool using 38 rats and 4 mice with mammary carcinoma. The study on the rats included study of the cutting, coagulating and vaporizing effect on brain tissue including study of blood brain barrier disruption and heat dissipation. The study on the mice included the study of vaporizing property of the probe on solid tumours. The probe proved to be an excellent tool for cutting, coagulating and vaporizing purposes with very minimal disruption of blood brain barrier and demonstrated well circumscribed heating pattern. The study indicates that this tool combines the beneficial effect of both the YAG and CO2 laser.

Electromagnetic field focusing (EFF) probe for intravascular endarterectomy. Preliminary feasibility study.

SummaryVaporization of atheromas in 10 human aorta segments immersed under flowing blood in vitro were done using the EFF probe. No increase in packed cells of the flowing blood following atheroma vaporization were noted suggesting absence of post vaporization debris. No damage to the aorta underlying the vaporized atheroma was noted on light microscopy suggesting well localized vaporization process. This study suggests that EFF probe might be a safe tool for intravascular endarterectomy.

Effects of Cocaine on Canines' Coronary Arteries:

Nine canines were anesthetized with pentobarbital and studied by both selective and semiselective coronary artery angiography following intravenous bolus doses of 1,3,5,8, or 10 mg/kg of cocaine. Catheterization was accomplished with a 5 Fr catheter over a 0.035 inch guidewire under fluoroscopic control, and angio grams were obtained by injection of a diatrizoate solution. Digital subtraction angiography (DSA) was performed prior to cocaine administration and at minutes 0.5, 1,1.5, 3, 5, and, in some cases, minutes 10 and 15 after cocaine administra tion. The 1 and 3 mg/kg doses of cocaine had no effect on the coronary arter ies. The 5 mg/kg dose significantly dilated the coronary arteries. The 8 mg/kg dose produced significant dilation at 30 seconds after cocaine but nonsignifi cant dilation of the coronary arteries at all other times. The 10 mg/kg dose produced significant dilation at 30 seconds, nonsignificant dilation at 60 seconds followed by significant constriction at 90 seconds after cocaine, which led to immediate death in most animals. The coronary dilation and constriction produced by 10 mg/kg of cocaine could be prevented by either preadministra tion or postadministration of naloxone, but this did not prevent subsequent death.

Electromagnetic Field Focusing (EFF) Probe: Applications in Aneurysm Treatment, Angioplasty, and Brain Tumor Resection

The electromagnetic field focusing (EFF) probe described in this chapter is a new precision surgical tool (US patent pending file No. 906791). It has either a hand-held or an extended form such as a catheter. It produces an intense tissue vaporizing temperature in a precisely defined manner comparable to CO2 laser. Unlike lasers, the EFF probe features tactile operation (i.e., action on touch only) such that the depth hazard associated with lasers is absent. The EFF probe simultaneously cuts (vaporizes) and cauterizes biological tissues except cortical bone. Cauterizing alone can be attained at a lower power setting.

Experimental Surgical Aneurysms in the Rat

Three different surgical methods were used to create experimental models of aneurysms in rats. The first model was an autogeneous side-to-side anastomosis of the inferior vena cava to the abdominal aorta. This model proved to be ac ceptable for acute preparations but was not amenable to survival surgery since occlusion of the venous circulation occurred. The second model developed was a renal vein aneurysm that was created in either of two ways: (1) the left renal vein was ligated at its juncture with the inferior vena cava and a partial ne phrectomy performed, or (2) the left renal vein was ligated in the same manner, as well as the inferior suprarenal artery. With either technique, the aneurysm developed within five to ten minutes. This model was technically satisfactory but also occluded the venous circulation as the first method had. The third model developed was a heterogeneous aorta of a donor animal grafted to the abdominal aorta of a recipient animal. This model proved to be best for survival surgery and gave patent aneurysms up to one week following surgery.