A model to describe the size distribution of mammalian genomic fragments recovered by microcloning.

Experiments involving the use of microdissection and microcloning of mammalian chromosomes to obtain genomic clones from individual chromosome regions have demonstrated an aberrant clone recovery. The number average microclone size is well below the empirically observed number average size of genomic restriction fragments. A model is proposed that describes the distribution of microclone sizes by the use of two parameters: (1) the frequency of restriction-enzyme cleavage per bp and (2) the frequency of a second DNA event per bp. The model assumes that any DNA fragment subject to this second event is unclonable. The model shows good fit to the observed microclone size distribution from various experiments when the frequency of the second event is of the order of 0.01. The nature of the second event is unknown but it likely represents a hydrolytic event on the DNA caused by acid fixation of metaphase chromosomes prior to microdissection and microcloning.

Characterisation of phosphate binding to mitochondrial and bacterial membrane-bound ATP synthase by studies of inhibition with 4-chloro-7-nitrobenzofurazan.

The effect of phosphate on the inhibition by 4-chloro-7-nitrobenzofurazan of the ATPase activity of the proton-translocating ATP synthase in heart submitochondrial particles was investigated. Binding of phosphate protected strongly against the inhibition. A dissociation constant of 0.2 mM was determined for the enzyme X Pi complex and shown to be independent of pH in the range 7.0-8.0. The protective effect of phosphate was mimicked by arsenate but not by sulphate or malonate. Similar results were obtained for the enzyme from Paracoccus denitrificans. 2,4-Dinitrophenol enhanced phosphate binding to the mitochondrial enzyme since the protective effect of phosphate was increased. The data are compatible with protection arising from binding of phosphate to a catalytic site.

Evaluation of gastrointestinal bleeding by red blood cells labeled in vivo with technetium-99m.

To determine the effectiveness of abdominal imaging with RBCs labeled in vivo with Tc-99m, for the detection of gastrointestinal (GI) bleeding, 28 control subjects and ten patients with suspected bleeding underwent scintigraphy at 0-24 hr after tracer injection. Colonic activity was noted in one of the controls within 3 hr of injection, and in five of ten controls at 24 hr, all of whom had initial gastric activity. Of the ten patients with suspected GI bleeding, eight had documented active bleeding; seven of these had positive scintigrams. Nasogastric (NG) suction markedly decreased the presence of initial gastric activity in the patients with active bleeding. With this blood-pool radiopharmaceutical, frequent imaging of the abdomen over 24 hr can be done to test active bleeding. Continuous NG suction is recommended to reduce accumulation of gastric activity. These results suggest that red blood cells labeled in vivo with Tc-99m provide a sensitive method of detecting active GI bleeding.

Intraoperative localization of small bowel bleeding sites with combined use of angiographic methods and methylene blue injection.

Superselective catheter placement with angiographic techniques and methylene blue injection at laparotomy through a prepositioned angiographic catheter have helped to localize small bowel bleeding lesions. The technique has been applied successfully in two patients with arteriovenous malformations and one patient with bleeding mucosal ulcerations of the small bowel.

Anatomic localization of atherosclerotic lesions by hemodynamic tests.

Use of noninvasive tests to assess the severity of lower-extremity occlusive lesions is generally accepted. To evaluate the effectiveness of noninvasive vascular-laboratory tests in locating atherosclerotic lesions, the results of hemodynamic studies in 100 patients were reviewed by both skilled observers and a vascular computer, and compared with angiograms. The results of the comparison suggest a remarkable sensitivity of the vascular-laboratory tests in locating significant arterial obstructions, and underscore that the great predictive value of a negative results gives the physician reliable information on the patency of a given arterial segment. Computer interpretation proved less accurate than that of the vascular-laboratory personnel.

Peripheral laser-assisted balloon angioplasty. Initial multicenter experience in 219 peripheral arteries.

In this multicenter clinical series of peripheral laser-assisted balloon angioplasty with an argon laser-heated, metallic-capped fiberoptic, angiographic and clinical success was achieved in a total of 155 (71%) of 219 attempted lesions. When the anatomy of the lesion was subjectively categorized by the angiographer into those considered possible or impossible to treat by conventional balloon angioplasty, clinical success was achieved in 116 (78%) of 149 lesions considered possible to treat with balloon angioplasty (39 [95%] of 41 stenoses and 77 [71%] of 108 occlusions). More importantly, clinical success was achieved in 39 (56%) of 70 lesions considered impossible to treat by conventional means. The incidence of complications, including vessel perforation (4.1%), with this new technique was equal to that reported for conventional balloon angioplasty, decreased with operator experience, and was less than that reported for argon laser angioplasty with bare fiberoptics. Thus, laser thermal angioplasty with a laser-heated, metallic-capped fiberoptic is a safe procedure that is easily learned by physicians skilled in interventional techniques. It allows for nonsurgical treatment of lesions considered difficult or impossible to treat by conventional balloon angioplasty.

Transluminal angioplasty of the iliac and femoropopliteal arteries. Current status.

Transluminal angioplasty for the management of atherosclerosis obliterans has been performed in 160 patients for 100 iliac and 98 femoropopliteal lesions. The procedure was performed percutaneously except in eight patients in whom operative exposure was required. Angioplasty was technically successful in all 100 iliac artery lesions. There was hemodynamic and clinical improvement in 92 lesions. The procedure was technically successful in 84 of the 98 femoropopliteal artery lesions with hemodynamic improvement in 74 and clinical improvement in 78. There were ten complications directly related to the angioplasty and six related to the arteriographic procedure. Cumulative patency rates for the angioplasties were 92% and 75% at three years for iliac and femoropopliteal lesions, respectively. These promising results suggest that transluminal angioplasty has a definite role in the management of atherosclerosis obliterans of iliac and femoropopliteal arteries.

Perineal abscess after embolization for high-flow priapism.

High-flow priapism is unusual and is most often due to blunt perineal trauma with resultant laceration of the cavernosal artery, creating an arteriocavernosal fistula. Although few cases have been reported, the consensus on management appears to be embolization of the fistula with autologous clot, alone or in combination with Gelfoam. We present a case of high-flow priapism treated in this manner. The embolized pseudoaneurysm evolved into an abscess that eventually spread to the perineum. The rarity of this entity and the postprocedural morbidity are reported.

Regional hepatic chemotherapy using an implantable drug infusion pump.

Regional infusion of chemotherapeutic agents in the treatment of liver cancer can greatly increase tumor exposure to certain drugs. Exposure is 100 times greater with floxuridine, 6 times greater with mitomycin C, and 6 times greater with BCNU. The Model 400 Infusaid implantable, refillable drug infusion pump overcomes much of the discomfort and inconvenience associated with previously employed extracorporeal systems. Our experience with our first 50 patients has been presented herein. Forty-one patients had metastatic colorectal cancer, 3 primary cancers, and 6 other metastatic cancers. Eleven pumps and 11 catheters were implanted at laparotomy. Thirty-nine patients had their pumps integrated to angiographically placed catheters. In over 260 patient months there were no pump malfunctions and only one infection. There were no vascular complications in the patients with angiographically placed catheters. Chemotherapeutic programs included floxuridine, floxuridine and radiotherapy, or floxuridine with mitomycin C and BCNU. In 18 patients with evaluable metastatic colorectal cancer who received hepatic arterial combination chemotherapy, there were therapeutic responses in 13 and disease stabilization in 4. The pumps were well tolerated by patients. They offer a reasonable approach to long-term ambulatory regional hepatic chemotherapy.

Hepatic and splenic infarctions: complications of therapeutic transcatheter embolization.

Two cases are described in which therapeutic transcatheter Gelfoam embolization was complicated by fatal hepatic infarction in one patient and splenic infarction with abscess formation in another patient. These are unusual complications of this widely used therapeutic technique. The probable pathophysiology of these complications is discussed and suggestions for managing and avoiding them are made.

Combined transluminal angioplasty and infrainguinal reconstruction in multilevel atherosclerotic disease.

Patients with multilevel atherosclerotic disease represent a difficult surgical challenge. This report is a retrospective review of 46 patients who were treated using a combination of iliac transluminal angioplasty and infrainguinal reconstruction. There were 42 male and 4 female patients with an average age of 62 years (range: 40 to 74 years). Follow-up ranged from 1 month to 10 years (mean: 27.3 months). These patients had multiple health problems typical of patients with peripheral vascular disease, including coronary artery disease (67%), hypertension (61%), and diabetes mellitus (42%); 80% of the patients were smokers. Forty-one patients were treated for rest pain and/or tissue loss, while five were treated for incapacitating claudication. Forty-three patients had a combination of angioplasty and distal bypass, while 3 patients had a form of femoral endarterectomy. Iliac artery pressure gradients were reduced from 35.4 +/- 4 mm Hg preangioplasty to 0.6 +/- 0.3 mm Hg postangioplasty. The procedures were well tolerated with no mortality and four serious complications. Vascular laboratory studies showed an improvement in the mean ankle-brachial index from 0.35 +/- 0.03 preoperatively to 0.71 +/- 0.04 postoperatively (p less than 0.05). Life-table analysis revealed a 72% 5-year primary patency rate, with a 93% 5-year limb salvage. Eight patients required a secondary procedure to maintain limb salvage. Five patients underwent amputation, three due to early graft thrombosis and two due to late graft failure. We conclude that combined iliac angioplasty and infrainguinal reconstruction is a safe and effective method for managing the patient with severe multilevel atherosclerotic disease.

Transcatheter embolization for the control of wound hemorrhage following hip surgery.

Angiography was done on sixteen patients with excessive bleeding from the wound following major hip surgery. In ten patients the bleeding site was so identified and the vessel was embolized with autologous clot or surgical gelatin. In six patients no site of bleeding could be seen. There was one angiographic complication: distal embolization to the popliteal artery. We concluded that angiography often may be helpful in localizing the site of excessive postoperative bleeding from a wound, and transcatheter embolization of the bleeding vessel then can be effective in controlling such bleeding.

New method for measuring the thermal conductivity.

A new experimental method is presented for measuring the thermal conductivity as a function of temperature. The basic innovation lies in extracting from the measured temperature profile of a sample in vacuo, the thermal conductivity of each individual cross-sectional sample element. The estimated experimental error is +/-1%. Not only is high accuracy achieved, but also a self-checking procedure offers the possibility of avoiding systematic errors. Measurements on two samples of type 304 stainless steel are presented. Three independent sets of measurements give consistent values for the thermal conductivity to well within the estimated error of +/-1%.

Constant-current supply of 3 ppm stability and resettability; application for a SQUID.

We describe a new design for a constant-current supply which is stable and resettable to 3 ppm over a period of one week, even in the presence of ambient temperature changes of several degrees. These characteristics are achieved by utilizing a digital-to-analog converter for providing a changeable, yet extremely stable, reference voltage. Seven full-scale current ranges are available between 0.1 and 100 mA. It is also shown that this constant-current supply is suitable even for use with a SQUID, meeting all of the exacting requirements for such use.

Inferior pancreaticoduodenal artery aneurysms in association with celiac axis stenosis or occlusion.

PURPOSE: To describe the pathophysiology, identification and management of inferior pancreaticoduodenal artery aneurysms in association with celiac axis stenosis or occlusion has been reported. REVIEW FINDINGS: These aneurysms are thought to arise due to increased flow through the pancreaticoduodenal arcades. The arcades first enlarge, and then form focal aneurysms which may rupture. The aneurysms can be treated through endovascular techniques or by surgery, though the former is a preferred approach.

Angioplasty for peripheral vascular disease.

Surgery is no longer the sole option for patients whose peripheral vascular disease requires treatment beyond conservative management; advances in angioplasty have allowed the physician to offer revascularization procedures even to patients who previously would not have been candidates for surgical reconstruction. Several issues, including the location, severity, and number of lesions and the feasibility of surgery, need to be considered in each case. A team approach, utilizing the skills and expertise of the vascular surgeon, the vascular radiologist (or other physician skilled in angioplasty), and the patient's physician, should ensure that the best choice is made for each patient.