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Biomedical subjects

A M Stone

Publications and source records attributed to A M Stone.

At least 37 records · Page 2Linked to original sources
PubMed1993

Endopyelotomy and endoureterotomy with the acucise ureteral cutting balloon device: preliminary experience.

Endoureterotomy and endopyelotomy usually involve an endoscopic antegrade approach. In an effort to simplify this technique, we designed an 8-mm balloon catheter with a 100-microns electrocautery cutting wire (Acucise) for retrograde incision of the ureter under fluoroscopic control. Twenty-eight patients with ureteral or ureteropelvic junction obstruction of 3.5 cm or less underwent Acucise endoureterotomy or endopyelotomy. The average operating time was 100 minutes, and the average hospital stay was 2.6 days. Follow-up was obtained with a subjective symptom score, intravenous urography, diuretic renal scan, a Whitaker test, or various combinations thereof. All patients had a minimum of 3 months of follow-up (mean 3.8 months; range 3-9 months). Overall, of the 21 patients who had symptoms of upper tract urinary obstruction, 14 (67%) had complete resolution, and another 4 (19%) had partial resolution, of their symptoms. Postoperative studies demonstrated normal upper tracts in 71% and improvement in another 14% of the patients. In our experience, the Acucise ureteral cutting balloon device provides an effective and efficient means for performing a retrograde endoureterotomy or endopyelotomy.

Catheterization↗
PubMed1993

Ligation of the renal pedicle during laparoscopic nephrectomy: a comparison of staples, clips, and sutures.

Evaluation of the role of staples, clips, and sutures for laparoscopic ligation of the renal artery revealed that occluding the renal artery with three, 9 mm titanium clips is as secure as occluding the renal artery with standard 2-0 and 0-silk ligatures. However, a triple staggered line of 2.5 mm staples placed across the renal artery was not as secure as either clips or silk sutures. The authors also studied eight female farm pigs who underwent laparoscopic nephroureterectomy with en masse stapled occlusion of the renal hilum. In one animal, an arteriovenous fistula was documented 6 months postoperatively. Currently, when laparoscopically occluding the renal hilum, the authors recommend a thorough dissection of the renal artery and renal vein; each should then be separately occluded so that three individually placed titanium clips remain on the stump of the renal artery and on the renal vein.

Animals↗
PubMed1993

Transforming growth factor beta (TGF-B) stimulation of angiogenesis: an electron microscopic study.

The object of this study was to examine the initiation and pattern of corneal angiogenesis stimulated by transforming growth factor beta (TGF-B) using scanning electron microscopy (SEM) of vascular corrosion casts and transmission electron microscopy (TEM). Fifty nanograms of TGF-B was combined with the slow release polymer Hydron and implanted in the rabbit cornea as an assay for angiogenic activity. Two and 7 days after implantation, the corneas were removed for TEM. At the same time intervals the limbal vasculature was filled with Mercox, an acrylic monomer. After the Mercox hardened, the tissue was digested with alternating immersions in 40% KOH and distilled water. The resulting casts were air-dried, sputter coated with gold and viewed with the scanning electron microscope. TEM revealed that 2 days after implantation, TGF-B elicited an influx of a vast number of inflammatory cells, which at two days were predominantly neutrophils. By 7 days the inflammation had subsided and typical capillaries were seen between the collagenous laminae of the normally avascular corneal stroma. SEM of vascular corrosion casts showed evidence of margination/diapedesis of leukocytes from the limbal venules 2 days post-implantation. In addition, the casts from the 7 day time point showed that new vessels arose solely from limbal venules.

Animals↗
PubMed1993

Retroperitoneal endoscopic adrenalectomy: an experimental study.

Laparoscopic approaches to adrenalectomy have been limited by the retroperitoneal (RP) location of the adrenal glands and their relative inaccessibility transabdominally. We developed a technique for endoscopic adrenalectomy in a domestic swine model using insufflation of the RP space with CO2 and retroperitoneoscopy. The technique for retroperitoneal endoscopic adrenalectomy was first developed in an acute study of three animals. A chronic survival study was then undertaken in six pigs. Unilateral right (n = 3) or left (n = 3) adrenalectomy was performed. Mean RP insufflation time was 14.5 min (range, 7-30 min), and mean dissection time after insufflation was 100 min (range, 80-120 min). Two additional animals died under anesthesia after RP insufflation and placement of the trocars for retroperitoneoscopy but before dissection of the adrenal gland. One death was unexplained at autopsy. The other death was associated with a right-sided pneumothorax attributable to penetration of the diaphragm by a trocar. The remaining six pigs recovered uneventfully from the procedure. Autopsies performed 37 to 51 days postoperatively showed minimal scarring of the adrenalectomy bed. The results suggest that posterior adrenalectomy using RP CO2 insufflation and direct retroperitoneoscopy is potentially applicable to the treatment of small adrenal lesions in humans.

Adrenalectomy↗
PubMed1992

The role of shame in post-traumatic stress disorder.

Shame is an important part of human experience but, by its very nature, is often neglected as an issue in treatment. Various recent conceptions of shame and its place in personality development, interpersonal relationships, and psychotherapy are presented. The contributions of affect theory are explored in their applications to the understanding of post-traumatic stress disorder, and implications for treatment are discussed.

Adaptation, Psychological↗
PubMed1991

The influence of exogenous eicosanoids on the radiation response of cultured bovine aortic endothelial cells.

The radioprotection by several eicosanoids was investigated in cultures of bovine aortic endothelial cells. One hour before irradiation (0-500 cGy, 137Cs gamma rays) 10 micrograms/ml of PGD2, PGE1, PGI2, misoprostol (PGE1-analog), 16,16-dimethyl PGE2, PGA2, or 1 microgram/ml LTC4 was added. Radiation decreased incorporation of [3H]thymidine at 4 h, cell number/culture at 24 h, and cell survival as measured by colony formation. Under these conditions the eicosanoids were not radioprotective. Two eicosanoids, PGD2 and PGA2, appeared to be toxic. Because receptors might mediate eicosanoid-induced radioprotection, radioligand binding of PGE2 and LTC4 and levels of adenosine 3',5'-cyclic monophosphate (cAMP) were measured. Evidence for a receptor was equivocal; there was nonspecific binding and metabolism of LTC4. The level of cAMP was elevated by 16-16-dimethyl-PGE2 in the presence of isobutyl methylxanthine; however, this combination of the prostaglandin and the methylxanthine was not radioprotective. These investigations suggest that an elevated cAMP level alone does not lead to eicosanoid-induced radioprotection of bovine aortic endothelial cell monolayers in vitro.

16,16-Dimethylprostaglandin E2↗
PubMed1989

Successful weaning from mechanical ventilation. Strategies to avoid failure.

The majority of patients who require mechanical ventilation can be weaned quickly from the ventilator. Patients with severe lung disease and multisystem disease often require a more prolonged, gradual reduction of ventilatory support. Identification of patients who are ready to be weaned, correction of common problems that occur in weaning, and use of a standard approach during weaning trials can improve the likelihood of successful discontinuation of mechanical ventilation.

Humans↗
PubMed1985

Effect of steroids on the cardiac output and renal changes of bacteremia.

The effects of methyl prednisolone pretreatment in dogs prior to a bacterial infusion were measured in relation to cardiac output, blood pressure, intrarenal blood flow, and glomerular filtration rate. In dogs not pretreated with steroid, cardiac output fell 61.1 per cent 30 min postbacterial infusion and remained depressed for the balance of the experiment. Pretreated animals showed a similar 61 per cent depression in cardiac output immediately following bacterial infusion, but then experienced recovery of cardiac output and blood pressure to levels not significantly different from controls at the conclusion of the experiment. Changes in outer cortical bloodflow and glomerular filtration rate were not affected by steroid pretreatment. Based on the above data, the author concludes that the salutary effect of steroid pretreatment on cardiovascular dynamics occurs independently of changes in renal function.

Animals↗
PubMed1983

Gastric mucosal blood flow and Escherichia coli bacteremia.

The specific changes in gastric blood flow during sepsis are controversial. Previous investigations of intragastric blood flow using endotoxin models revealed decreased total gastric blood flow and decreased gastric mucosal blood flow. Endotoxin models are now thought to be inadequate due to the accompanying depression of the systemic circulation. More recently, increased gastric blood flow has been demonstrated in a septic hindlimb model. To further elucidate the changes in intragastric blood flow in sepsis, the gastric mucosal and nonmucosal blood flow were measured in the antrum and corpus of pig stomachs before and after the onset of sepsis. Increased gastric mucosal blood flow was demonstrated in both the antrum and corpus 15 minutes after the onset of E. coli bacteremia. By 75 minutes postonset, the changes were not significant, which implied partial recovery. Clinically, gastric mucosal ulcers may accompany the multiple organ system failure of sepsis. These data suggest that mucosal ischemia is not an etiologic factor as previously postulated from experiments with endotoxin.

Animals↗
PubMed1983

Pancreatic nesidioblastosis in adults. Report of a patient with hyperinsulinemic hypoglycemia.

Hyperinsulinemic hypoglycemia in neonates occurs most commonly secondary to nesidioblastosis, a persistence of fetal development of the endocrine cells of the pancreas. In adults, hyperinsulinemic hypoglycemia is usually due to insulinoma or beta-cell hyperplasia. Nesidioblastosis arising in adults has only recently been reported. An adult patient with nesidioblastosis has been described. The light and electron microscopic films of this entity are shown in detail, and the embryology and treatment are discussed. Further understanding of this newly described disease entity will require research on factors that regulate the differentiation of beta cells of the pancreas.

Female↗
PubMed1983

Indomethacin and the gastric mucosal blood flow changes of sepsis.

Recent evidence suggests that sepsis results in increased gastric mucosal blood flow (GMBF). To investigate the possible role of prostaglandins in mediating this response, the GMBF was measured in the fundus, corpus, and antrum of pig stomachs with and without pretreatment with indomethacin, an inhibitor of prostaglandin synthesis, before and after the induction of bacteremia. The studies were done in 22 piglets (seven sepsis controls, seven indomethacin controls and eight experimental [indomethacin pretreated sepsis] ). Sepsis was produced in piglets by bolus intravenous injection of 10(9) live Escherichia coli followed by an infusion of 10(9) E. coli/hr. Cardiac output (C.O.) was measured by thermodilution. GMBF was measured by microsphere trapping. Following sacrifice, hyperemia was noted in the sepsis group but not in the other groups. GMBF was determined by standard techniques (expressed as ml/min/100 gm tissue). There were significant (p less than 0.05) increases in gastric mucosal blood flow to the fundus (+47%), corpus (+50%), and antrum (+101%) at 15 minutes following the onset of E. coli infusion. At 135 minutes, the increase was only significant in the antrum. GMBF, however, did not change in the indomethacin control or indomethacin pretreated sepsis groups. These data demonstrate GMBF in the stomach following sepsis. The changes were not present in the indomethacin control or in the indomethacin pretreated sepsis groups. Since indomethacin is an inhibitor of prostaglandin synthesis, the results suggest that the GMBF may be a prostaglandin mediated response.

Animals↗
PubMed1980

The effects of Escherichia coli bacteremia on in vitro perfused kidneys.

The renal response to sepsis results in increased renal blood flow, decreased renal vascular resistance, polyuric renal failure and a change in intracortical renal blood distribution. Prior reports used whole animal preparations, where the effects of sepsis on other organs may have led to systemic vasoactive changes altering the experimental model. To elucidate the direct effect of gram negative bacteremia on the kidney, intracortical hemodynamics and urinary flow were investigated using isolated canine kidneys perfused with a nonpulsatile pump oxygenator primed with modified dog plasma. Bacteremia was produced by 2.5 x 10(11) live Escherichia coli organisms infused directly into the perfusate. Intracortical blood flow distribution was measured by radioactive microsphere trapping using 15 microns diameter plastic radioactive microspheres. Urine flow increased 157% (p less than 0.05) following E. coli bacteremia while intracortical blood distribution was unchanged. The polyuric renal failure of sepsis is therefore, a direct result of bacteremia and not secondary to a change in intracortical flow as previously reported. The changes in intracortical blood distribution reported previously in sepsis using intact animal models probably reflect the renal response to release of vasoactive compounds originating in other organs rather than an intrinsic renal reaction to bacteremia.

Animals↗
PubMed1980

Mesenteric hernia.

Acute intestinal obstruction secondary to an idiopathic mesenteric hernia has been reviewed by collecting 139 reports from the literature and studying them from the standpoint of incidence, etiology, pathogenesis, clinical manifestations, diagnosis, treatment and mortality. An acute intestinal obstruction with strangulation in the absence of an external hernia and with no history of previous surgical procedures must suggest the possibility of an internal hernia, especially if the patient has a history of chronic intermittent abdominal distress and a palpable abdominal mass if found on examination.

Adolescent↗
PubMed1979

Changes in intrarenal blood flow during sepsis.

The intrarenal hemodynamics of nine dogs were studied using 15 micron diameter plastic radioactive microspheres labeled with either 85Sr or 141Ce injected before and with the alternative isotope injected 30 minutes after the induction of sepsis. Total renal microsphere trapping increased by 30.6 per cent, p less than 0.01, after the induction of sepsis. The glomerular filtration rate was unchanged. Microsphere trapping in the outer and inner cortex increased by 36.9 per cent, p less than 0.005, and by 20.3 per cent, p less than 0.05, respectively, reflecting increased renal blood flow. Fractional renal microsphere distribution in the outer cortex increased from 70.0 to 73.4 per cent, p less than 0.01, following the induction of sepsis. These data confirm that sepsis results in renal vasodilatation. In addition, a shift in intrarenal blood flow to the outer cortex was demonstrated. Since the outer cortex is perfused with blood which first passes through the inner cortex, it can be hypothesized that renal blood flow in septic states may be passing through dilated glomerular vessels unable to trap microspheres in the inner cortex or passing through precapillary open arteriovenous shunts, or both, thereby bypassing inner cortical functioning glomeruli. This may partly explain the decreased renal function associated with increased renal blood flow in septic states.

Animals↗
PubMed1979

Renal vascular effects of stroma and stroma-free hemoglobin.

To assess the renal effects of hemoglobulin infusion, intrarenal hemodynamics were studied in 14 dogs using radioactive microspheres following the infusion of hemoglobin and stroma. Fractional renal microsphere distribution in the outer cortex remained at control levels following the infusion of hemoglobin. When the infusion of stroma followed, there was a 4.3 per cent, p less than 0.01, increase in the outer cortex microsphere distribution at the expense of the inner cortex, p less than 0.05. When the order was reversed, the stroma suspension being infused first, again there was a significant increase in the outer cortex distribution--6.1 per cent; p less than 0.01. When the infusion of hemoglobin followed, the outer cortex microsphere trapping reverted to control levels. These data revealed no effect upon intrarenal blood flow following the infusion of hemoglobin. The previously reported renal toxicity of hemoglobin infusion is, therefore, probably secondary to contamination with stroma. Hemoglobin should be further investigated for use as an ideal resuscitation fluid.

Animals↗