Maternal atherogenic diet in swine is protective against early atherosclerosis development in offspring consuming an atherogenic diet post-natally.

Atherosclerosis found early in life suggests that it may arise from fetal adaptations during development in utero. We evaluated the effect of a maternal atherogenic diet on atherosclerosis development in offspring. Aortic fat deposition was evaluated by Sudan IV staining and coronary atherosclerosis was assessed histologically. Sows were fed an atherogenic diet (ath) or standard diet (std) throughout gestation. Twelve neonates (six per maternal diet group) were evaluated with no significant differences noted (P>0.05) in serum lipids or aortic fat deposition and there was no evidence of coronary atherosclerosis. Twenty offspring (10 per maternal diet group) were followed for 5 months forming the pubertal age group. Half of these swine received an atherogenic (ATH) diet (std-ATH and ath-ATH) and half received a standard (STD) diet (std-STD and ath-STD). Pubertal age swine on the ATH diet had significantly greater (P<0.05) serum lipids and aortic fat deposition compared with those on the STD diet, with significantly greater fat deposition (P<0.05) occurring in the std-ATH versus ath-ATH group. Coronary atherosclerosis was exhibited only in the std-ATH diet group. Our findings suggest that gestational diet may alter the body's management of cholesterol later in life, possibly providing a protective effect from atherosclerosis.

Effects of angioplasty balloon inflation time on arterial contractions and mechanics.

The purpose of this study was to characterize and compare the immediate effects of short and long angioplasty inflation times on arterial contractions and passive mechanics and thereby determine if there is a potential advantage obtained by increasing the duration of balloon inflation. In each of 10 nonatherosclerotic New Zealand rabbits, one external iliac artery was dilated for 20 seconds, and the contralateral artery was dilated for 2 minutes. Although angioplasty stretched the arteries 27% and 30% for the short and long dilations respectively, the pre- and post-angioplasty arteriographic diameters were not different. Both short and long dilations had equal effects on passive biomechanics: circumferential wall stress was increased (P less than .01); wall thickness was decreased (P less than .01); the incremental elastic modulus was increased (P less than .01). In vitro studies of arterial rings demonstrated that maximal active contractile force in response to KCl (70 mM) was significantly (P less than .05) less for dilated arteries than for undilated arteries. More importantly, maximal active force after the 2-minute dilations was significantly (P less than .05) less than after the 20-second dilations. These results suggest that, when dilating normal arteries, increasing angioplasty balloon inflation time from 20 seconds to 2 minutes offers no mechanical advantage but produces more smooth muscle cell dysfunction, which may reduce vasospasm and restenosis after angioplasty.

Angioplasty-induced vasospasm in rabbit model. Mechanisms and treatment.

Angioplasty of the distal iliac and proximal femoral arteries in rabbits resulted in focal and diffuse vasospasm similar to that seen in humans. The focal vasospasm occurred in all experiments immediately distal to the site of angioplasty. Occasional diffuse vasospasm was preceded by intravascular thrombosis or extravasation. Heparin reduced the incidence of diffuse vasospasm and reduced the severity of focal vasospasm. Verapamil and Dazoxiben reversed focal vasospasm, but only Verapamil in the presence of heparin prevented vasospasm. Prazocin had no effect on vasospasm.

Sources of error in arterial morphometric measurements.

The authors used radiopaque vascular casts to test a new computer-based analysis method that employs a densitometric profile to determine arterial diameters. Results from this method were compared with those obtained with caliper measurements of overhead projection images of the radiograph and direct caliper measurements of the vascular cast. In addition, the corresponding in vivo angiograms were compared with the measurements obtained from the vascular casts. Vessel diameters obtained from cast radiographs by caliper measurement, operator-determined and automated densitometric curve fitting showed excellent correlations with acceptable intraobserver and interobserver variation. All methods, however, underestimated arterial diameters by about 7% compared with diameters obtained from casts by direct caliper measurements. In vivo angiograms revealed smaller arterial diameters than those obtained from specimens. However, we observed higher correlations for measurements at stenotic sites than in non-stenotic regions. Our results suggest definite limitations for the often used direct comparison between in vivo angiographic and postmortem findings.

New rabbit atherosclerosis model for the investigation of transluminal angioplasty.

In order to investigate the long-term and short-term effects of transluminal angioplasty, an animal model was developed that closely simulates human disease. Using the Flemish Giant rabbit, lesions were created by air-drying an isolated segment of femoral artery and feeding the rabbits a diet of 2% cholesterol, 6% peanut oil for one month. The lesions were studied with serial angiography for up to three months and with correlative histology. The results showed focal, stenotic lesions that appeared stable over time and had histologic similarity to human lesions. the artery adjacent to the lesions appeared normal. Since the femoral arteries in this rabbit strain are sufficiently large to undergo angioplasty, and it is possible to perform serial angiograms, it is believed that this model is suitable for use in the investigation of angioplasty, and the preliminary work confirms its feasibility.

Morphometric changes in normal arteries and those undergoing transluminal angioplasty.

To understand the morphometric effects of balloon catheter angioplasty in autopsy specimens, we studied the effect of histologic preparation on the size of control arterial specimens (N) and those having angioplasty at room temperature (CD) or body temperature (WD). Diameters of external and internal iliac arteries were measured with calipers, photography, and X-rays without any distention, after 200 mm Hg in a balloon catheter, after angioplasty to 4 atmospheres, and after fixation with a balloon catheter in place was inflated to 200 mm Hg. Arterial diameters were also taken from the tissue blocks and histologic slides. Images taken from the photos, X-rays, tissue blocks, and slides were digitized, and the diameter was calculated from circumference measurements. Diameters increased approximately 30% (P less than .001) when distended from the resting state to 200 mm Hg. There was a 7.4-8.2% decrease in diameter of arteries in blocks (P less than .01) and a further decrease of 9.8-11.9% from block to slide (P less than .005). Thus, significant size changes occur during arterial preparation. The postmortem artery shrinks without any distending pressure. Paraffin embedding and slide preparation are also associated with significant decreases in arterial size. These changes may influence the understanding of the pathophysiology of angioplasty and the estimation of stenoses by histopathology.

Ultrasound-assisted thrombolysis.

RATIONALE AND OBJECTIVES: Current use of thrombolytic agents to lyse thrombus, though safe, is complicated by stroke, bleeding, and clot embolization. Therapy may be protracted, resulting in further ischemia and possible tissue loss. Peripheral arterial and graft occlusions often require several hours of thrombolytic therapy, which may occasionally exceed 48 hours and may also require expensive intensive care monitoring. It is desirable to accelerate clot lysis and to thereby reduce the risks and costs associated with the procedure and minimize morbidity. In this article, the authors propose the use of intravascular ultrasound in conjunction with thrombolytic agents to increase the rate of thrombolysis. METHODS AND RESULTS: In-vitro thrombolysis of fresh human blood clots was studied with and without urokinase by using continuous wave, 20-KHz ultrasound at the power levels 1-2 watts. Loss in weight of each clot was used to measure the extent of thrombolysis. Clot lysis was observed when ultrasound and thrombolytic agents were used alone. At modest power levels of 1.0 to 1.5 watts of ultrasonic energy a significant increase in lysis was observed in conjunction with 5,000 units of urokinase. CONCLUSIONS: In the short treatment duration of this in-vitro study, 5,000 units of urokinase combined with 20-KHz ultrasound energy at 1.0 and 1.5 watts was associated with a greater percentage thrombolysis by weight than either urokinase or ultrasound alone.

Permanent percutaneous antegrade ureteral stent placement without transurethral assistance.

A simple, one-step, permanent, percutaneous, antegrade insertion of a ureteral stent is described, utilizing a double, pigtail catheter. No transurethral assistance is necessary. The advantages of this simplified technique are presented, and the necessary prerequisites for its application are discussed.

Computed masks in coronary subtraction imaging.

In this paper we propose a method to overcome the effects of cardiac and respiratory motion in coronary subtraction imaging. We present the ideas of retrospective gating of masks, where both cardiac and respiratory phases are measured for a set of masks, and are subsequently used in a functional decomposition of motion. Through retrospective gating of masks, we are able to select appropriate images and to perform temporal and spatial processing on them to produce computed masks, subtraction of which should lead to motion-artifact-free images. The computed masks are built from two components: the first includes the time-variant structures related to respiration, such as ribs and soft tissues of the chest wall, and the second incorporates the time-variant structures related to cardiac motion. A preliminary study of the method in the area of digital subtraction angiography produced images which are comparable to but not better than those produced by techniques in current clinical practice: we discuss the reasons for this.

Awakenings to the pathogenicity of urease and the requirement for continuous long term therapy.

Urease is an enzyme found in plants and bacteria, but not mammals. It catalyzes the conversion of urea to carbon dioxide and ammonia. Ammonia shortens the life span of cells; and higher concentrations cause tissue necrosis and cytolysis. Twenty percent of total body urea is converted to ammonia by bacterial urease in the colon. Small injections of urease immunize animals by producing antiurease, a gamma globulin, which inactivates urease. Immunization eliminates the colonic conversion of urea to ammonia. Injection of urease produces ammonia intoxication making immunization hazardous. Although previously impossible, a non enzymatic urease antigen was synthesized by covalently bonding jack bean urease with glutaraldehyde. This antigen stimulated the production of antiurease that inactivates native urease. Helicobacter pylori, a potent urease producer, has been implicated in peptic ulcer, gastritis and other inflammatory bowel lesions. The pathogenicity of H pylori is dependent on its urease production. Immunization to urease can render H pylori non pathogenic. Cirrhotics develop encephalopathy and hyperammonemia because their livers fail to convert all the ammonia in portal venous blood to urea and collaterals develop by passing the liver. Colonic ammonia increases the turnover rate of colonic mucosa. Ammonia absorbed into the portal venous system is transported to the liver where it is reconverted to urea. Absorbed ammonia adversely influences liver function. Infections with urease producing organisms destroy the renal parenchyma and produce struvite stones. Urease immunization aids colonic healing and prevents uremic colitis. Absorbed ammonia is a noxious influence on the liver. Animals immunized to urease regenerate the liver faster and are less susceptible to hepatotoxins. Immunization to urease ameliorates cirrhosis. Proteus and other urease producers become non toxic and do not damage the renal parenchyma. Urease is responsible for the pathogenicity of infections with urease producing organisms. Immunization to urease renders urease producing organisms non pathogenic.

Photoplethysmographic documentation of improved microcirculation after pentoxifylline therapy.

Pentoxifylline is the prototype of a new class of drugs that improve peripheral blood flow mainly by increasing red blood cell flexibility. Few studies have been performed to objectively evaluate the effect of the drug in a routine clinical setting. In 11 patients with intermittent claudication, photoplethysmography was used to monitor the effect of pentoxifylline on the microcirculation in the lower extremities. Values obtained improved significantly (p less than .0001) under therapy. Concomitant measurements of ankle-brachial indices showed no significant changes despite clinical improvement. Diabetic patients in this study seemed to benefit from treatment with pentoxifylline at least as much as nondiabetic patients. Photoplethysmography proved to be a very efficient and inexpensive method of studying the effects of pentoxifylline. Ankle-brachial indices are not a suitable method of detecting flow changes attributable to the mechanism of action of this drug.

Carbon dioxide digital subtraction angiography: the practical approach.

CO(2) has developed into a viable alternative to iodinated contrast for digital vascular imaging. Because CO(2) is a gas, it has a unique set of properties that affords certain advantages over iodinated contrast in a variety of settings. However, if CO(2) is used inappropriately, these same properties are associated with a unique set of rare but potentially harmful events. Therefore, it is essential that these unique characteristics be understood in order to employ a few simple precautionary measures. Fortunately, there is a delivery system currently available that is readily assembled and easy to use that ensures the appropriate administration of CO(2). This system, combined with experience, can reduce the greater labor intensity sometimes associated with CO(2) digital subtraction angiography. When it is used appropriately, CO(2) digital subtraction angiography alone or in combination with iodinated contrast offers diagnostic and interventional rewards that are not available with traditional intravascular contrast examinations.

Preliminary abdominal films in oral cholecystography: are they necessary?

A survey of 45 radiologists with a special interest in gastrointestinal radiology showed that only 8% used a preliminary abdominal film for oral cholecystography. Review of 467 cases of oral cholecystography with preliminary films over a 1 year period disclosed 88 confirmed cases of cholelithiasis. Of these 88 cases, 27% had opaque gallstones visible on the preliminary film. In one-third of the cases, the opaque gallstones had a classic diagnostic appearance, while the remainder required oral cholecystography for confirmation. Opaque calculi were obscured by oral contrast material in 2% of cases. Other significant pathology on the preliminary films was found in 5.5% of the 467 cases.

Shear stress in the performance of esophageal dilation: comparison of balloon dilation and bougienage.

While both the balloon catheter and the bougie are effective for esophageal dilation, each has its proponents. From a biomechanical point of view, the two methods should differ significantly, since bougienage depends on advancing a tapered dilator to generate radial force and balloon catheter dilation depends solely on balloon inflation to generate its radial dilating force. In a series of equivalent esophageal stenoses made by suture plication in swine esophageal segments, the authors measured shear force and radial force generated by dilation with a Maloney bougie, a Savary-Gilliard bougie, and an esophageal balloon. The mean radial forces generated were 6.42, 4.46, and 4.04 N, respectively, which did not differ significantly. However, the mean shear forces measured were 16.92, 6.92, and 1.44 N, respectively. The shear force with the Maloney bougie differed significantly from that with the Savary-Gilliard and the balloon and was on the same order of magnitude as the tensile strength of the esophagus (25-27 N). The shear force with the balloon was significantly lower than that with either bougie. In theory, the reduced shear force associated with balloon dilation might reduce the risk of esophageal perforation, but safety will have to be determined in clinical trials.

The mythology of povidone-iodine and the development of self-sterilizing plastics.

The predominance of elemental iodine as a chemical antiseptic has been established during a century. Free iodine is effective for treatment and prevention of infection. Iodophors, such as povidone-iodine, have replaced elemental iodine in clinical use. Toxic absorption of povidone-iodine occurs from all tissues except intact adult skin, to which its use should be restricted. Povidone-iodine binds iodine so firmly that insufficient free iodine is released to be effective for treating or preventing infection. It is a weak antiseptic that is marginally acceptable as a disinfectant for adult skin. The shortcomings of povidone-iodine stimulated a search for iodophors that would liberate therapeutically effective concentrations of free iodine. These investigations led to a new self-sterilizing plastic formed by the complexing of polyurethane and iodine.

Pressure-infusion venography of the leg with remote-control fluoroscopy.

A method for lower-extremity venography using remote-control fluoroscopy and radiography, as well as pressure infusion of contrast media, is described. This technique combines the advantages of fluoroscopically-timed and positioned radiographs with the improved image and size of overhead views. There is less radiation exposure to the patient, radiologist, and technologist than with venography performed with conventional fluoroscopy.

Lymphangioma: one of the soft lesions of the colon.

Lymphangiomas are benign tumors most commonly found in the neck, axilla and skin. Occasionally they may occur in the gastrointestinal tract, most in the small intestine or mesentary. Lymphangioma of the colon is rare. Many of the reported cases, however, have manifested similar radiographic features. This case exemplifies the characteristic radiographic and colonoscopic features which may suggest the diagnosis.

Restenosis and successful angioplasty: histologic-radiologic correlation.

Histologic analysis was undertaken on 24 perfusion-fixed arteries from New Zealand White rabbits that had undergone percutaneous transluminal angioplasty (PTA) of a focal arteriosclerotic lesion in the femoral artery 1 month earlier. Experiments representative of occlusion, restenosis (greater than or equal to 50% stenosis), a good result (less than 50% stenosis), or aneurysm (as defined angiographically) were randomly selected for histologic analysis. Histologic findings were compared with those in untreated control lesions in the contralateral femoral artery. All good results (n = 11) but only four of seven restenoses had histologic evidence of a tear into the tunica media or the tunica adventitia (P = .017). Cases of tears to the adventitia were more likely to have a good result. New myointimal proliferation was more severe with restenosis (P less than .05). Occlusions and aneurysms appeared to be more severe expressions of the histologic findings observed in restenoses and good results, respectively. An arterial tear is necessary but not sufficient to obtain a good result after PTA; outcome is ultimately dependent on the degree of intimal hyperplasia.

Reduced vasoconstrictor response after angioplasty in normal rabbit aortas.

Angioplasty was performed on rabbit aortas in vivo. During balloon catheter inflations, the aortic diameters increased by 29%-75%; after deflation, there was persistent dilation of the treated segments by 11%-45%. Aortic strips removed from dilated and nondilated segments were tested for vasoconstrictor response in vitro. The vasoconstrictor response was attenuated in proportion to the effective stretch applied to the aorta in vivo. It was concluded that angioplasty can induce paralysis of smooth muscle.