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Biomedical subjects

G J Becker

Publications and source records attributed to G J Becker.

At least 127 records · Page 7Linked to original sources
PubMed1988

Radiofrequency balloon angioplasty. Rationale and proof of principle.

Post-angioplasty restenosis (PARS) in atherosclerotic lesions of medium and small arteries occurs in about one-third of cases in the first year following percutaneous transluminal angioplasty (PTA) (early PARS). PARS includes acute spasm, dissection with reclosure, elastic recoil, fibrocellular proliferative response, and progressive atheromatous disease. Fibrocellular proliferation (possibly initiated by platelet derived growth factor) is felt to be culpable in many cases of early PARS (months). Pharmacologic regimens, stents, and thermal welding of the intimal-medial cracks of PTA are among the interventions being developed to deal with PARS. Radiofrequency (RF) current as a source of thermal energy may be useful in combination with balloon angioplasty to reduce PARS. Ideally, this combination would (1) weld intimal-medial cracks of PTA; (2) mold plaque and normal vessel to increase lumen diameters without creating intimal-medial cracks; and (3) destroy medial smooth muscle cells and multipotential cells (cellular substrate of PARS). Canine in vivo studies have established the feasibility of RF-mediated vascular tissue welding. Human aortic specimens (N = 28) were manually dissected into intima-media and media-adventitia layers. Bipolar RF energy (650 KHz, total 300 J) and mechanical pressure (1 atm) (experimental group, N = 24) or mechanical pressure alone (control group, N = 4) were applied to the reapposed specimen layers in a special chamber. The chamber was modified with a bipolar electrode designed to reproduce that planned for an RF balloon angioplasty catheter. Welding was demonstrated in normal and atherosclerotic treated specimens (23/24 or 96%) but not controls (0/4).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1988

In vitro study of high-pressure catheters and various contrast agents.

The versatility of angiography has been expanded by the introduction of low-osmolality contrast agents; high-pressure, high-flow catheters with small outer diameters; and the use of contrast agents with low iodine concentrations. These changes have resulted in the need for a review of the physical factors that influence the flow of contrast agents through flush catheters. Various contrast agents were injected through several types of high-pressure, high-flow catheters with small outer diameters, and the flow rates were measured. Great differences in the viscosities of contrast agents resulted in proportionately smaller differences in maximum flow rates, and warming the contrast agent from room to body temperature had little effect on the maximum flow rate, except for the most viscous contrast agents. The maximum flow rates of the new low-osmolality contrast agents did not differ significantly from those of conventional ionic contrast agents of similar iodine concentration. With unheated contrast agents, iodine delivery was more rapid for contrast agents with iodine concentrations of 280-300 mg/mL.

Angiography↗
PubMed1988

Intraluminal stents in atherosclerotic iliac artery stenosis: preliminary report of a multicenter study.

Fifteen patients with symptomatic iliac artery stenosis were treated with intraluminal placement of balloon-expandable stents. Before treatment, 14 patients had intermittent claudication, and one had a limb at risk for amputation. One patient had diabetes mellitus, nine had hypertension, and all were long-term smokers. Two patients had surgical placement of the stent; in one patient this was part of a combined revascularization procedure. All other stents were placed percutaneously. The transstenotic gradient after injection of vasodilating drugs distal to the lesion decreased from a mean of 32.3 mm Hg +/- 16.7 to 3.1 mm Hg +/- 4.2 after stent placement. Ankle-arm Doppler systolic pressure index increased from a mean of 0.68 +/- 0.22 to 0.96 +/- 0.24 after the procedure. The treatment eliminated intermittent claudication in 14 patients and increased exercise tolerance to 500 m in the patient with a limb at risk for amputation before the procedure. The improved condition persisted in all patients during the follow-up of 6-12 months. Stent placement may be a valuable adjunct in the management of iliac artery disease.

Angiography↗
PubMed1988

Treatment of dural sinus thrombosis with local urokinase infusion. Case report.

Current therapy for dural sinus thrombosis consists of supportive measures, anticoagulation therapy, and in some cases intravenous infusion of a fibrinolytic agent. A patient with extensive dural sinus thrombosis was successfully treated with local urokinase infusion. The technique and rationale for this aggressive therapy are discussed.

Adult↗
PubMed1988

Renal failure and nephrotic syndrome associated with sulindac.

Four elderly patients developed nephrotic syndrome while receiving sulindac. Sulindac treatment had commenced 4-12 months prior to presentation with the nephrotic syndrome. Two patients also developed oliguric renal failure. Renal biopsy in one showed minimal change nephropathy and in three cases membranous nephropathy. Interstitial nephritis was present on renal biopsy in all cases. The nephrotic syndrome and renal failure resolved in all cases after withdrawal of sulindac. Two patients received steroid therapy and improvement in renal function and disappearance of proteinuria seemed to be temporarily related to steroid therapy in both cases. Despite the fact that sulindac is less likely to cause renal failure due to inhibition of renal prostaglandin secretion this report shows that sulindac treatment can be associated with renal failure and the nephrotic syndrome.

Acute Kidney Injury↗
PubMed1987

Elimination of enoxacin in renal disease.

The elimination of enoxacin was investigated in 15 subjects, 10 of whom were hospital outpatients with renal disease and varying degrees of renal impairment. Each was given enoxacin orally (200 mg b.i.d.) for 7 days. Blood specimens collected over 24 hours after the final dose of enoxacin and urine collected during the 12-hour dose interval after the final dose were assayed for enoxacin by HPLC. The elimination half-life of enoxacin increased with worsening renal function. In general, patients with diminished renal function had lower plasma enoxacin clearance values than had normal subjects, and a statistically significant correlation between apparent oral clearance and creatinine clearance was observed. Excretion of enoxacin by the kidney accounted for 26% to 72% of the apparent plasma clearance in normal subjects. This was markedly reduced in patients with severe renal failure.

Administration, Oral↗
PubMed1987

Morphometric aspects of reflux nephropathy.

We have studied the relationships between renal size, glomerular hypertrophy and sclerosis and renal function in adults with reflux nephropathy. A digitizer was used to measure the renal surface areas in intravenous pyelogram films. This was then corrected for patient size by dividing by the area of the first three lumbar vertebrae. In renal biopsies, glomerular surface area and the proportion of segmentally and globally sclerosed glomeruli were measured and compared with a control group of 17 renal donors. Of 57 patients studied, 45 had intravenous pyelogram films and 32 had renal biopsy tissue available from the time of presentation, 20 had both. Thirty-one were followed for two years or more (median 6 years, range 2 to 11 years). There were positive correlations between corrected renal size and renal function, and inverse correlations between these and maximum glomerular size, the proportion of sclerosed glomeruli and vascular wall thickness. Proteinuria correlated best with the proportion of segmentally sclerosed glomeruli. As a prognostic guide, the strongest correlations were between rate of functional decline and percent segmental sclerosis, urine protein excretion and creatinine clearance at presentation. These studies confirm expected relationships between renal size, glomerular size and renal function and suggest that the severity of segmental sclerosis is a major factor in eventual decline into renal failure.

Adolescent↗
PubMed1987

Detection of acute gastrointestinal bleeding by intra-arterial Tc-99m sulfur colloid scintigraphy in a canine model. Preliminary study.

The diagnostic sensitivities of arteriography, intravenous (IV) Tc-99m sulfur colloid scintigraphy, and intra-arterial (IA) Tc-99m sulfur colloid scintigraphy were evaluated in a canine model of gastrointestinal bleeding. Fifteen dogs were studied at bleeding rates ranging from .4 to 1.0 ml/minute. All three studies were obtained in six of the 15 dogs. Intravenous scintigraphy was superior to angiography in two cases, inferior in three, and equal in one. No significant difference could be shown between these two tests at these bleeding rates. Intra-arterial scintigraphy was superior to angiography in four cases and equal in two (P = .06). It was superior to IV scintigraphy in five cases and inferior in one (P = .10). In this small preliminary study, IA scintigraphy appears to be superior to the other two modalities and may prove useful in the detection of acute bleeding at the time of negative arteriography, and in serial studies in patients receiving Pitressin.

Acute Disease↗
PubMed1987

Bronchial artery embolization: monitoring with somatosensory evoked potentials. Work in progress.

Surgery remains the treatment of choice for massive and recurrent hemoptysis. In some instances, however, immediate surgical intervention is contraindicated. In these situations, bronchial artery embolization (BAE) has proved to be a successful definitive treatment for non-surgical candidates and a palliative therapy in patients requiring hemodynamic stabilization prior to surgery. The most serious complication of BAE is spinal cord ischemia. This relates directly to the potential anastomotic connections between the bronchial circulation and the anterior spinal artery. Somatosensory evoked potentials (SSEPs) have been used in the past to monitor spinal cord ischemia during procedures that threaten the vascularity of the spinal cord. The authors report two cases in which SSEPs were employed to monitor spinal cord ischemia during bronchial artery embolization.

Aged↗
PubMed1987

Interventional radiology for restoration of vascular patency in the postoperative patient--case reports.

The postoperative patient may present with one or more of a variety of problems amenable to management by interventional radiologic techniques, which may be curative by themselves or may, in addition, require or allow successful surgical intervention. To optimize patient care, a good working relationship between the vascular surgeon and the interventional radiologist is essential. Consideration should be given to the patient's presenting signs and symptoms, the surgical history with its alteration of anatomy, the results of available noninvasive studies, and knowledge of various therapeutic alternatives. Vascular radiologic interventions include angioplasty, thrombolytic therapy, a combination of both angioplasty and thrombolysis, and newer techniques such as percutaneous valvectomy. In this report, examples of some of the experience at Indiana University are presented. Emphasis is placed on the appropriate approach to the patient.

Adult↗
PubMed1987

Serum sickness nephropathy in the rat using cationized albumin: effect of preimmunization and antigen dose.

A model of glomerulonephritis induced in preimmunized rats with cationic albumin is described. Extensive glomerular immune complex formation and a severe nephrotic syndrome occurred within 5 days of commencement of daily intravenous injections. Severity of disease was markedly influenced by the degree of preimmunization and, to a lesser extent, by the dose of cationic albumin administered. Immune deposits, although initially confined along the capillary loops, were seen at all sites in the glomerulus. This study confirms that, in rats, the use of cationic antigens accelerates the development of 'serum sickness' nephropathy but preimmunization is necessary to produce significant disease.

Animals↗
PubMed1987

Rapid development of diffuse crescents in post-streptococcal glomerulonephritis.

A 14-year-old boy presented with 3 days of hematuria and oliguria following impetigo. Renal biopsy showed diffuse endocapillary proliferative glomerulonephritis with subendothelial electron dense deposits but no crescents. Due to recrudescence of clinical abnormalities after initial improvement, the patient was re-biopsied 10 days later. This biopsy showed circumferential crescents in 83% of the glomeruli. Treatment with intensive plasma exchange, prednisolone, cyclophosphamide and dipyridamole was accompanied by prompt improvement in renal function. The need to carefully monitor the course in patients with acute post-streptococcal glomerulonephritis is emphasized.

Adolescent↗