Direct vision valvulotomy for nonreversed vein graft

A new and easy technique using an angioscope in a nonreversed, isolated vein bypass is suggested herein. Direct vision valvulotomy with an angioscope in nonreversed vein graft saves operating time, prevents tearing of the vein wall and inaccurate incision of the valves.

Phospholipid methylation in canine myocardium: kinetic characteristics and the effect of endotoxin administration

The kinetic characteristics and the effect of endotoxin administration on the enzymatic methylation of phospholipids in dog heart microsomes were studied using S-adenosyl-L-[methyl-3H]methionine as a methyl donor. Kinetic studies in control dogs reveal that the stepwise methylation of phosphatidylethanolamine to phosphatidylcholine was catalyzed by three different enzymes. Methyltransferase I catalyzed the methylation of phosphatidylethanolamine to phosphatidyl-N-monomethylethanolamine, had a very low Km (approximately 1.5 microM) for S-adenosylmethionine, and a pH optimum of 6.5, and it was stimulated by Mg2+ and Ca2+. Methyltransferase II catalyzed the methylation of phosphatidyl-N-monomethylethanolamine to phosphatidyl-N,N-dimethylethanolamine, had a low Km (8-12 microM) for S-adenosylmethionine, and a pH optimum of 8.5, and it was stimulated by low concentrations (less than 1 mM) of Ca2+ but was unaffected by Mg2+. Methyltransferase III catalyzed the formation of phosphatidylcholine from phosphatidyl-N,N-dimethylethanolamine, had a high Km (approximately 33 microM) for S-adenosylmethionine, and a pH optimum of 9.5, and it was unaffected by Mg2+ or Ca2+. Experiments with trypsin digestion indicate that methyltransferases I and III were partially embedded while methyltransferase II was completely exposed to the surface of the membrane. Endotoxin administration (2 and 4 hr) decreased the Km and Vmax by 30 to 36% and 24 to 37.7%, respectively, for S-adenosylmethionine. Since the enzymatic methylation of phospholipids has been implicated to play an important role in the regulation of membrane structure and function, the endotoxin-induced decreases in the Km and Vmax of phospholipid-methylating enzymes in dog heart microsomes may contribute to the development of myocardial dysfunction in endotoxin shock.

Thermolabile proton translocating ATPase and pump activities in a clathrin-coated vesicle fraction from an acidification defective Chinese hamster cell line

We have recently described a mutant of Chinese hamster ovary cells, termed G.7.1, that contains a temperature-sensitive, conditionally lethal mutation resulting in defective vacuolar acidification (Marnell, M. H., Mathis, L. S., Stookey, M., Shia, S.-P., Stone, D.K., and Draper, R. K. (1984) J. Cell Biol. 99, 1907-1916). To further characterize the lesion, clathrin-coated vesicles were partially purified from wild type and G.7.1 cells, and the thermolabilities of vanadate and oligomycin-insensitive, N-ethylmaleimide-sensitive, H+-ATPase activity, 32Pi-ATPase exchange activity, and proton pumping were compared. All three parameters of H+ pump activity were markedly diminished by preincubation at 44 degrees C for vesicles harvested from the G.7.1 cells, but not for those from wild type cells. Phosphatidylserine did not protect against heat inactivation in vesicle fractions prepared from G.7.1 cells. The results suggest that the mutation responsible for defective acidification in G.7.1 cells is expressed at the level of the proton pump of organelles present in our clathrin-coated vesicle-enriched preparation.

Argon laser angioplasty with a laser probe

A preliminary basic study of argon laser angioplasty with the use of a specially designed probe is presented. Arterial specimens were harvested from 10 amputated lower extremities. The studies included the evaluation of coaxial laser angioplasty in 10 partially or totally occluded arteries; the observation of the effect of perpendicularly applied laser energy on 35 thrombi, 54 soft and 10 hard atherosclerotic, and 51 normal arterial walls; the comparison of laser energy requirements for coaxial vessel lumen enlargement or recanalization vs. perpendicular penetration in 10 occluded, hard atherosclerotic arteries; and the spectrographic analysis of calcium density gradient in two specimens. The results showed that the power required for vessel lumen enlargement was 10 +/- 6 J/mm of atherosclerotic vessel (mean +/- standard deviation). The probe followed the original arterial lumen, did not perforate the vessel wall, and created a smooth, enlarged path. The power required to penetrate perpendicularly to a similar depth for thrombi, soft and hard atherosclerotic plaques, and normal arterial walls was 15 +/- 4, 30 +/- 15, 65 +/- 32, and 246 +/- 123 J/mm, respectively. In the hard calcified specimens, laser energy required for coaxial lumen enlargement or recanalization was significantly less than that for perpendicular penetration (p less than 0.05), which correlated with the calcium density map indicating an increase from inside to outside.

Intimal response of saphenous vein to intraluminal trauma by stimulated angioscopic insertion

Endothelial damage after simulated angioscopic insertion was evaluated in 22 dogs by radioimmunoassay of endogenous 6-keto-prostaglandin F1 alpha (stable product of prostacyclin produced by the endothelium) by means of a closed perfusion system and scanning electron microscopy. In 20 dogs, a 1.7 mm diameter polyethylene tube similar in size and physical characteristics to a commercially available angioscope was passed once into the distal venotomy site and out of the proximal venotomy site for a total distance of 15 cm in the left saphenous vein (group A) and 10 times in both directions in the right saphenous vein, destroying all valves (group B). The vein segments were examined immediately after simulated angioscopic insertion and at intervals of 2, 3, and 4 weeks. The remaining two dogs were used as control animals to establish baseline prostacyclin production. All veins were patent when harvested. Scanning electron microscopy revealed globular and contracted endothelial cells in some areas of group A veins, whereas partial longitudinal absence of endothelial cells was noted in group B veins. Intimal coverage was complete by 2 weeks in group A veins and between 3 and 4 weeks in group B veins. Prostacyclin synthesis of group B veins was significantly less than that of group A at day 1 and at 2 weeks after operation (p less than 0.05), reaching that of control vein synthesis by 4 weeks. This study suggests that simulated angioscopic trauma of the luminal surface of the canine saphenous vein had no negative effect on early patency.

Role of enteric plexuses in the competency of telescoped intestinal valves

The mechanism of preventing intestinal regurgitation by means of a telescoped intestinal valve has been investigated in this study. Ten telescoped intestinal valves were uniformly created in dogs. A tolerance test to barium reflux was performed before the animals were sacrificed 16 weeks postoperatively, which yielded various barium tolerance values. Statistical analysis revealed that the differences in barium tolerance values in the uniformly constructed valves were closely related to the proportion of the enteric plexuses which contained ganglion cells with normal shapes (r = 0.97, p less than 0.001) and their intestinal segment coverage (r = 0.94, p less than 0.001), but no correlation was found between barium tolerance and the thickness of the valvular musculature (r = 0.04) or the length of the artificial valve (r = 0.39). The results in this study suggest that the intact enteric plexuses play an important role in modulating the competency of the telescoped intestinal valve.

Use of intragastric balloons for weight reduction. An experimental study

The effect of intragastric balloons as a noninvasive method for weight reduction was observed in nine castrated Yorkshire pigs. None of the animals lost weight. The appetites of the experimental animals were inhibited for only a short period of time. A significant dilatation of the stomach after balloon insertion was noted which resulted from increased food intake and obliterated the effect of the intragastric balloons. A long-standing lower blood glucose level played an important role in the increments in food intake and dilatation of the stomach. At the same time, ulceration was seen in 83.3 percent of the animals that received balloons. We conclude that intragastric balloon therapy may not be an effective approach for managing morbid obesity in human subjects.

Relationships between ionizing radiation, bone marrow transplantation and leukemogenesis

Studies of the relationships between ionizing radiation, bone marrow transplantation and leukemogenesis were carried out in 343 LACA mice. The recipients (female) were given whole-body irradiation with 7 or 8 Gy of Co-60 gamma-rays, while the donors (male) were given whole-body irradiation with 3, 1.5, 0.5, 0.1, 0.05 and 0 Gy of Co-60 gamma-rays. Each recipient was intravenously infused with 1-3 X 10(7) of the mixed marrow cells of donors. In the result, the average incidence of surviving over 1 month was 86% in the recipients. Myelocytic leukemia developed in all the transplanted groups, the average incidence being 88.5%. Leukemia was observed in 1.5-2.5 months after transplantation in the recipients receiving marrow cells from donors exposed to 3 Gy, but in 5-8 months in other groups. It was demonstrated by the analysis of Y-chromosome that the leukemic cells were derived from the donor's marrow cells. The results suggest that marrow transplantation for the mice irradiated by Co-60 gamma-rays of lethal dose can protect them from death, but promote the development of leukemia. Radiation can induce production of factors which lead to leukemic transformation of engrafted normal marrow cells in the irradiated mice; the direct damage of DNA caused by radiation is not the unique factor that gives rise to leukemia.

Patterns of pannus growth of the expanded polytetrafluoroethylene vascular graft with special attention to the intimal hyperplasia formation

Serial histologic observations of the healing process of expanded polytetrafluoroethylene (PTFE) vascular grafts in dogs were performed. The common iliac arteries of 12 mongrel dogs were replaced with a 2-cm segment of 6 mm PTFE graft, bilaterally. The grafts were studied microscopically after the animals were killed at 4, 8, 12, 16, 20, and 24 weeks. All the grafts remained patent up to 24 weeks. Special attention was paid to the histological characteristics of pannus growth, which were divided into two types: smooth appearing and irregular. The former type was characterized by smooth, thinner connective tissue growth along the graft, and the latter was defined as irregular-shaped pannus containing large and small thrombi. Only pannus of the smooth type showed similar growth patterns and growth rates. These findings suggest essentially that pannus develops smoothly from both ends of the graft; however, thrombi disturbed this growth pattern. In 24 grafts, eight nodular lesions of the pannus (greater than 500 mu in height) were found: five distally and three proximally. All eight lesions were found within 3 mm of the anastomoses. Among these eight lesions, five were on the completely healed pannus, and the remainings were all on the irregular pannus. This suggests that thrombi organization followed by nodular lesions are major offending factors that lead to the formation of intimal hyperplasia.

The competence and bacteriologic effect of the telescoped intestinal valve after small bowel resection

In 20 dogs the distal one-third of the small intestine and the proximal 10 cm of the ascending colon were resected. Bowel continuity was established by the telescoping technique to create an intestinal valve in ten dogs (group A) and by conventional end-to-end anastomosis in ten dogs (group B). Diarrhea and weight loss were similar in both groups. The ileal bacterial growth was significantly higher than the jejunum in group A (P less than 0.001) but not in group B. The jejunal bacterial growth in group B was significantly higher than that in group A (P less than 0.01). Intestinal transit times were 212 +/- 16.0, 219 +/- 152.4, and 163 +/- 85.8 minutes for normal dogs, groups A and B respectively. The competence of the normal ileocecal valve, the telescoped valve, and conventional anastomosis were 56 +/- 1.7, 49.9 +/- 17.4 and 13.2 +/- 7.8 cm of barium, respectively. Artificial intestinal valve formed by the telescoping technique is safe, simple, and effective in reducing bacterial overgrowth in the jejunum and appears to prolong intestinal transit time.

The healing and tensile strength of the gastroplasty staple line. An experimental study

Inverted and everted staple lines, with and without division of the anterior gastric wall, were performed in 15 mongrel dogs to simulate reduction gastroplasty staple line. There were no significant differences in tensile strength and healing between staple lines at different postoperative periods. The tensile strength of the inverted staple line seemed to be stronger due to breakage of the adjacent gastric tissue. However, the tensile strength of the everted stapling without division of the gastric wall, which is used clinically, was almost equal to that of normal gastric tissue. In addition, there was satisfactory healing 4 weeks postoperatively in the everted stapling without dividing the gastric wall. These results suggest that the everted staple line without division of stomach is not inherently weaker to any significant extent than if the gastric wall was divided or inverted. The reported failure rate of this procedure may be due to other factors.

Intestinal valve formation with a simple invagination technique

In 17 fully conditioned mongrel dogs, the small intestine approximately 50 cm proximal to the ileocecal valve was divided. Three centimeters of the proximal bowel was then inserted into the distal bowel and anastomosis was performed using interrupted 3-0 Dexon sutures in the seromuscular layer of the proximal end and through the entire thickness of the distal end. Two to four dogs were then sacrificed 2, 4, 6, 8, and 10 weeks postoperatively. Two dogs died 3 and 4 weeks postoperatively due to mechanical obstruction just proximal to the anastomosis by hair bezoar, and 15 survived without complications. Retrograde contrast radiologic examination of all segments showed no reflux. Microscopically, the serosal surface of the invaginated segment was found to be gradually covered with mucosa, and the whole segment formed a valvelike structure within 10 weeks time.

Electron microscopy of bacteriophage phi 6 nucleocapsid: three-dimensional image analysis

Electron micrographs of bacteriophage phi 6 nucleocapsids, negatively stained by neutralized phosphotungstate and tilted in a goniometer specimen cartridge, proved that the three distinct morphologies seen in the electron microscope are merely three different aspects of a single nucleocapsid structure and strongly suggested that this structure is dodecahedral.