Prostatic hyperplasia: radiological intervention. Work in progress

Benign prostatic hypertrophy is the most common cause for urethral obstruction in males over 50 years of age. Interventional radiologic dilatation under fluoroscopic control offers a nonoperative alternative for treatment of prostatic hyperplasia. Cadaver studies with the use of arteriographic balloon catheters indicated that manual injection pressure provides effective dilatation of the prostatic urethra. Evaluation of symptom relief will have to await patient studies.     

Tissue relaxation time: in vivo field dependence

Relaxation times (T1 and T2) were measured in vivo in mongrel dogs at fields of 0.3, 0.5, 1.0, 1.35, and 1.5 tesla (T). T1 was measured using nine values of inversion time ranging from 10 to 1,280 msec. T2 was measured with a four-point multiple spin-echo sequence. Relaxation times were calculated for muscle, kidney cortex, spleen, and adipose tissue. T2 is independent of field. A linear fit to the field dependence of T1 yields slopes of 400-500 msec/T for tissues in which the primary source of protons is water. The lower slope of adipose (approximately 150 msec/T) reflects the different mechanism of spin-lattice relaxation of the -CH2 protons.     

Normal brain iodine-125 radiation damage: effect of dose and irradiated volume in a canine model

High-activity iodine-125 sources in plastic catheters were surgically placed in the cerebral white matter of healthy beagle dogs and later removed. Reference doses, calculated at a point 0.75 mm from the source, ranged from 10 to 40 Gy. Necrosis, vascular-related damage, and edema were quantified by computed tomography. Volumetric analyses were used to derive the relationship of dose and dose rate to necrosis and contrast enhancement. The extent of necrosis was related to irradiated volume; a minimum effective dose averaging 180-200 Gy was required to induce this type of damage. Contrast enhancement was less dependent on irradiated volume or total dose. The extent of radiation-induced edema was directly related to the volumes of necrosis plus contrast enhancement. Noninvasive serial studies in a well-characterized in vivo model can address specific clinically related questions on damage to normal tissue after interstitial irradiation.     

Percutaneous vascular intervention after surgical shunting for portal hypertension

Twenty percutaneous transluminal angioplasty (PTA) procedures and 13 percutaneous venous embolization (PVE) procedures were performed in 23 patients who either had or were at risk for the development of recurrent bleeding, hepatic encephalopathy, or both after surgical shunt placement for portal hypertension. PTA, performed in 12 patients with significant shunt stenoses, resulted in reduction or elimination of gradients in all patients; rebleeding has occurred in only one patient. Complications consisted of one fatal rupture of a mesocaval interposition vein graft and one balloon rupture requiring surgical removal. PVE, performed in 11 patients, resulted in measurable improvement in four of seven encephalopathic patients and temporary control in the two patients with intractable bleeding. Three patients underwent PVE prophylactically. PTA of graft strictures is a valuable treatment modality. Embolization may be helpful in selected cases of hepatic encephalopathy.     

Lithium stimulation of murine hematopoiesis in liquid culture: an effect mediated by marrow stromal cells

Lithium has previously been observed to stimulate in vitro Dexter culture hemopoiesis with increases in granulocytes, megakaryocytes, and pluripotent stem cells (CFU-S). In the present study, a two-phase murine Dexter culture system was established to study the mechanism of lithium-mediated stem cell stimulation. Different lots of horse sera or fetal calf sera were found to have markedly different effects on Dexter culture growth; given the appropriate sera supplementation, supernatant cells from Dexter cultures established from C57BL/6J mice 3 wk previously were free of stromal-forming capacity, but had stem cells and could grow on 900-950 R irradiated stroma. Conversely, in vitro irradiation (900-950 R) of 3-wk cultures resulted in a stem-cell-free adherent monolayer that could support growth for up to 9 wk in culture. The stroma from Dexter cultures preexposed to lithium chloride (1.0 mmole/liter) for 3 wk, irradiated (900 R), and then refed with 3-wk Dexter supernatant cells has an enhanced capacity to support cell production, CFU-S, and probably granulocyte-macrophage colony-forming cell (GM-CFU-C) production, as compared to stroma not preexposed to lithium. Lithium carryover was ruled out in these experiments. These data indicate that lithium stimulates CFU-S and in vitro granulopoiesis by an indirect effect on a radioresistant adherent stromal cell.