Will transcatheter embolotherapy replace surgery in the treatment of gastrointestinal bleeding?(2)(2).

Superselective angiography and transcatheter embolization (SATE) have produced mixed results in the treatment of upper gastrointestinal bleeding (UGIB). The use of SATE to treat hemorrhage distal to the ligament of Treitz has been approached with trepidation because of limited collateral blood supply to the gastrointestinal tract beyond the duodenum. Ischemic bowel injury rates of 15% to 35% are reported when SATE is used to treat lower gastrointestinal bleeding (LGIB). Recent improvements in coaxial catheter design and embolic agents and greater expertise of personnel performing interventional angiographic procedures have decreased the risks of SATE in the lower gastrointestinal tract. The purpose of this study is to review our experience with SATE in the management of both UGIB and LGIB. %METHODS:This is a retrospective cohort study of patients undergoing SATE between January 1996 and November 1998. All SATE was performed in an angiographic suite with the latest generation coaxial catheters and embolic agents. Patient characteristics and outcome measures were noted. Efficacy of SATE was determined by analyzing the following outcome measures: initial technical success, rebleeding rate at less than 30 days post-SATE, the total rebleeding rate post-SATE, the number of patients requiring surgery despite SATE, and the complication rate. Patients undergoing SATE for LGIB were clinically monitored for development of ischemic complications.Of 523 admissions for UGIB and LGIB, 35 patients (6.7%) underwent SATE as definitive therapy for control of gastrointestinal hemorrhage (25 UGIB and 10 LGIB). Mean age of treated patients was 67 years; 49% had greater than 3 significant systemic comorbidities. Initial control of bleeding was achieved in 23/25 UGIB and 10/10 LGIB patients. Rebleeding at less than 30 days occurred in 5/23 UGIB and 2/10 LGIB patients. Rebleeding at greater than 30 days occurred in 2 additional UGIB patients. No known duodenal stenosis or ischemic bowel injury occurred in patients undergoing SATE for UGIB or LGIB, respectively, during the follow-up period.SATE is an excellent therapeutic method for GI bleeding in selected patients, and definitive control is frequently afforded. In the remainder, SATE may allow temporary control and resuscitation of the unstable patient. SATE appears to be as safe and effective for LGIB as it is for UGIB. Further studies are needed to better define the role of SATE for GI bleeding.

Stent-graft repair of mycotic superficial femoral artery aneurysm using a Palmaz stent and autologous saphenous vein.

Developing endoluminal technology has permitted the management of selected aneurysms using stent-grafts, but the applicability and durability of these new devices has not yet been proven. Standard treatment of mycotic aneurysms generally requires arterial ligation, excision and debridement, and autologous or extraanatomic synthetic bypass. A saphenous vein-covered stent was used to exclude an expanding, mycotic, superficial femoral artery aneurysm in a critically ill patient. Although stent-graft exclusion was intended as a bridge to standard therapy, the mass resolved, the superficial femoral artery remains patent, and the patient is symptom-free at 1 year without further intervention. Additional experience is required to determine whether stent-grafts have a role in the management of mycotic aneurysms.

Should balloon angioplasty and stents have any role in operative intervention for lower extremity ischemia?

Balloon angioplasty has been combined with open vascular surgery to treat lower extremity ischemia due to multilevel occlusive disease. The purposes of this study were: (1) to compare staged and simultaneous approaches to determine the optimal method for combining endovascular and open techniques and; (2) to assess the role of stents in intraoperative balloon angioplasty. Among 274 patients undergoing lower extremity revascularization over 30 months, 38 (13.9%) required a combination of endovascular and open techniques; 17 were staged (endovascular followed at an interval by distal open surgery) and 21 were simultaneous (intraoperative balloon angioplasty with or without stent placement at the time of open surgery). Groups were similar with respect to demographics, lesions treated with endovascular intervention, incidence and location of stent placement, and results of surgery. Additional operating time required for intraoperative endovascular intervention was 41.0 +/- 30.7 min., fluoroscopic time was 3.9 +/- 2.4 min. and contrast administered was 58.8 +/- 28.1 ml. There was no perioperative mortality. Length of stay was longer in the staged than in the simultaneous group (p < 0.01). Cumulative combined primary patency at 1 year by life-table methods was 82 +/- 10% in the staged group and 83 +/- 9% in the simultaneous group (p = 0.79). Mean follow-up was 13 +/- 6 months. There is a role for balloon angioplasty and stent placement in operative revascularization of ischemic limbs in selected patients: patency was similar to that produced with the staged approach while the length of stay was shorter. Intraoperative balloon angioplasty is safe and effective and stents permit a measure of control in assuring an optimal intraoperative postangioplasty result.

Synapsis of attachment sites during lambda integrative recombination involves capture of a naked DNA by a protein-DNA complex.

During lambda integration, Int recombinase must specifically bind to and cut attachment sites on both the viral and host chromosomes. We show here by foot-printing and by a novel cleavage assay that the bacterial attachment site, attB, cannot stably bind Int in competition with other DNAs. Instead, during recombination reactions, attB obtains its Int by collision with the intasome, a nucleoprotein assembly that forms on the viral attachment site, attP. Our cleavage assay also shows that the capture of attB by the attP intasome does not depend on DNA homology between the two sites; synapsis is governed solely by protein-protein and protein-DNA interactions.

The interaction of recombination proteins with supercoiled DNA: defining the role of supercoiling in lambda integrative recombination.

Lambda integrative recombination depends on supercoiling of the phage attachment site, attP. Using dimethylsulfate protection and indirect end-labeling, the interaction of the recombination proteins Int and IHF with supercoiled and linear attP has been studied. Supercoiling enhances the binding of Int to attP, but not if a truncated attP site is employed or if IHF is omitted. We reason that the altered affinity reflects the formation of a higher-order nucleoprotein structure, an "attP intasome," that involves Int and IHF assembly of both arms of attP into a wrapped configuration. The good correlation between the degree and sign of supercoiling needed to promote recombination and that needed for the "attP intasome" indicates that the primary role of supercoiling is to drive the formation of the wrapped structure.

The c-myc oncogene is translocated to the involved chromosome 12 in mouse plasmacytoma.

Although it is known that the c-myc oncogene is rearranged in a head-to-head fashion with the immunoglobulin heavy chain locus in mouse plasmacytomas, it has not been clear whether the c-myc oncogene is translocated to the heavy chain locus on mouse chromosome 12 or whether the heavy chain locus is translocated to the c-myc locus on mouse chromosome 15. To determine which of these two possibilities is correct, we hybridized Chinese hamster fibroblasts with J558 mouse plasmacytoma cells that carry a reciprocal chromosome translocation between chromosomes 12 and 15, and we examined the segregating hybrids for the presence of the normal and rearranged mouse c-myc genes, for the presence of different regions of the mouse heavy chain locus, and for the presence of genes located on mouse chromosomes 12 and 15. The results of this analysis indicate that, as in human Burkitt lymphomas with the 8;14 chromosome translocation, the c-myc gene is translocated to the heavy chain locus in mouse plasmacytomas. Thus the orientation of the heavy chain locus on mouse chromosome 12 and of the c-myc gene on mouse chromosome 15 is the same as the orientation of the homologous loci in man.