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Biomedical subjects

G J Becker

Publications and source records attributed to G J Becker.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Creation of a modified angiography (endovascular) suite for transluminal endograft placement and combined interventional-surgical procedures.

PURPOSE: To describe early experience with an endovascular suite created for procedures requiring surgical access, endograft placement, or combined surgical and interventional radiologic expertise. MATERIALS AND METHODS: After examining the operating room and angiography environments, practice guidelines, state law, and regulatory agency requirements, a multidepartmental task force recommended reconfiguring an angiography suite to serve as an endovascular suite. Forty patients have been treated; 28 underwent vascular endograft placement and 12 underwent other combined procedures. RESULTS: Procedures included 31 femoral and axillary cutdowns; placement of one aortobifemoral graft, two iliofemoral grafts, two femoropopliteal grafts, and two femoral-femoral crossover grafts; two abdominopelvic exposures for aortic access, and five endarterectomies, including one at the carotid bifurcation performed in combination with common carotid stent placement. Three of the abdominopelvic procedures were not planned, including two emergency conversions. No patient had to be moved to an operating room. There was one major infection (2.5%), two minor wound infections (5%), and one wound with delayed healing (2.5%). CONCLUSION: Early experience with a combined surgical-interventional suite has been favorable, but a vigilant approach is warranted.

Angiography↗
PubMedDate not supplied

The double-tuck model: a new animal model of arterial thrombosis.

PURPOSE: To develop an animal model of a fibrin- and platelet-rich intraluminal arterial thrombus with abnormal mural substrate to simulate in situ thrombosis of human atherosclerotic arteries. MATERIALS AND METHODS: Parallel studies of the crush-thrombin model (CT) and double-tuck model (DT) were performed and evaluated with use of angiography and histologic analysis. Ten Yorkshire swine (1-6 months; 20-30 kg; 10 females) underwent right femoral and carotid cutdowns performed after administration of general anesthesia (4 mL intravenous thiopental sodium, isoflurane 2% in 1 L of oxygen). After angiography, the CT model was created in the left carotid artery and the DT model was performed in the right carotid artery. Angiograms were obtained at 20 minutes (n = 1), at 1 hour (n = 3), at 2 hours (n = 4), and at 3 hours (n = 2) before sacrifice. After sacrifice, histologic specimens were stained with hematoxylin-eosin (H-E stain) and phosphotungstic acid hematoxylin for fibrin. The specimens were examined for endothelial irregularity and adhesion, platelet aggregation, fibrin layering, vessel wall injury, and adventitial hemorrhage. The findings were quantified as 0 = absent, 1+ = slight, 2+ = moderate, and 3+ = severe. RESULTS: Angiographic results were similar. However, histologic analysis of the CT model showed severe damage to the arterial wall with dissection in nine of 10 animals. In the DT model, no dissection was found (n = 10). Endothelial irregularity was found in six of 10 arteries treated with the CT method, as compared with nine of 10 arteries prepared with the DT model; endothelial adhesion was found in five DT arteries and in four CT arteries. Platelet aggregation was present equally in both methods. A fibrin- and platelet-rich thrombus was created in five of 10 examined arteries by both methods. CONCLUSIONS: The DT model creates endothelial irregularity leading to formation of a platelet- and fibrin-rich thrombus, adherent to the vessel wall without damage to the media. This contrasts with the CT method, which created medial dissection in nine of 10 arteries. One hour is the minimum time required to produce a good quality thrombus; 2 hours is the optimum time. The DT model is proposed as a useful tool in the development of new devices, drugs, and biotechnologic advances.

Angiography↗
PubMedDate not supplied

Influence of cardiac function on the quality of intravenous digital subtraction arteriograms.

In a retrospective comparison between 22 pairs of matched intravenous digital subtraction angiogram (DSA) images, five angiographers made independent determinations as to which one of each pair was superior in image quality (110 image comparisons). Matched pairs were identical for anatomic region filmed, catheter position during injection, amount of contrast material injected, injection rate, and iodine concentration of the contrast material. Each pair consisted of images from one patient with a normal (less than 1 S.D. above the mean) sodium dehydrocholate circulation time and images from one patient with a prolonged (greater than 1 S.D. above the mean) circulation time. In 85 of the 110 instances (77.3%) an image judged superior in quality to its matched counterpart derived from a DSA exam in a patient with normal circulation time; images from the exam with prolonged circulation time were judged equal in quality to the ones with the normal circulation time in 14 comparisons (12.3%); in 11 comparisons (10%) the images from the DSA with the prolonged circulation time were judged superior to the ones from the DSA with the normal circulation time. These results show that with statistically significant frequency (P less than 0.001) observers judge intravenous DSA images deriving from patients with normal circulation times superior in quality to those deriving from patients with prolonged circulation times.

Angiography↗
PubMedDate not supplied

Pentoxifylline reduces in vitro renal myofibroblast proliferation and collagen secretion.

Interstitial myofibroblasts (MF) are cells with features of both smooth muscle cells and fibroblasts. They have been universally recognized in situations of tubulointerstitial injury, where their presence has been shown to be a marker of disease progression. The objective of this study was to determine if functions of MF relevant to fibrogenesis can be modified in vitro by the phosphodiesterase inhibitor pentoxifylline (PTX). MF were obtained from sub-culture of normal rat kidney explant outgrowths maintained in DMEM + 20% fetal calf serum (FCS), supplemented with antibiotics. Cells were characterized on the basis of growth characteristics and immunohistochemistry. MF constituted >95% of cells at passage 3. Cell culture media was supplemented with the potential antagonist PTX alone (0, 1, 10, 100 microg/ml) and in combination with TGFbeta(1) (5 ng/ml). Population kinetics, proliferation and collagen production were determined from cell growth, [(3)H]thymidine incorporation and [(3)H]proline incorporation in collagenous proteins, respectively. Both serum-stimulated population growth and proliferation were reduced in a linear fashion by 1, 10 and 100 microg/ml PTX (all p < 0.05 versus 0 microg/ml). Effect of PTX on cell population growth was however reversible when PTX was removed. Basal collagen secretion was decreased by PTX at 10 and 100 microg/ml (p < 0.05 versus 0 microg/ml although layer collagen remained unchanged. Collagen production (secreted and cell layer) was augmented by 5 ng/ml TGFbeta(1). These effects on collagen production were partially reduced when 100 microg/ml PTX was added. The authors conclude that myofibroblast function can be altered with agonists/antagonists. Attempts to down-regulate fibrogenic functions of MF may therefore offer a valuable therapeutic strategy.

Animals↗
PubMedDate not supplied

Anteromedial tibial tubercle transfer without bone graft.

We followed 30 patients for more than 2 years after anteromedial tibial tubercle transfer for persistent patellofemoral pain associated with patellar articular degeneration. Twelve of these patients were followed more than 5 years. We report 93% good and excellent results subjectively and 89% good and excellent results objectively. The quality of improvement was sustained in all 12 of the patients who were evaluated again after more than 5 years from surgery. When examined separately, 75% of those patients with advanced patellar arthrosis achieved a good result; none of these patients achieved an excellent result. Postoperative continuous passive motion has markedly reduced the incidence of stiffness. Serious complications such as compartment syndrome, infection, and skin slough were avoided completely in 51 consecutive cases. Patellofemoral contact pressure studies in five cadaver knees have shown that anteromedial tibial tubercle transfer can provide substantial reduction of patellofemoral contact stress while helping to balance medial and lateral facet pressures. This surgical procedure is mechanically and clinically successful for alleviating intractable pain related to patellar malalignment and articular degeneration. This procedure enables the majority of appropriately selected patients with malalignment and patellar articular degeneration to resume increased levels of activity with substantially diminished pain.

Adolescent↗
PubMedDate not supplied

Healing after arterial dilatation with radiofrequency thermal and nonthermal balloon angioplasty systems.

Thermal balloon angioplasty has been proposed as a means of reducing acute and delayed reclosure of arteries after percutaneous transluminal balloon angioplasty. A radiofrequency (rf) balloon catheter was used to perform thermal balloon angioplasty on canine arteries in vivo. The histologic appearance of rf-treated sites was compared with that of control sites treated by conventional percutaneous transluminal angioplasty. Acutely, rf-treated sites showed a reduced medial cellularity with preservation of internal elastic lamina except at the transitional zone between thermal injury and normal artery, where localized internal elastic lamina disruption was found. Nonthermal sites showed generalized disruption of internal elastic lamina and normal medial cellularity. Both thermal and nonthermal sites displayed a return of intimal cover commencing at 1 to 2 weeks and completed by 4 weeks. Diffuse myointimal hyperplasia appeared by 2 weeks after injury at breaks in the internal elastic lamina along the nonthermal vessels but was localized to the transitional zone in thermal injury sites. In rf-treated vessels, repopulation of the acellular thermally modified media had commenced by 4 weeks, and by 8 weeks the media was diffusely repopulated by spindle-shaped cells resembling smooth muscle cells lying between and aligned with preserved connective tissue laminae. Overall, the distribution and extent of the proliferative response after rf thermal balloon angioplasty were less than those seen after nonthermal balloon angioplasty. Thermal sites, which underwent reintimalization before medial cells returned, were considerably less prone to the development of myointimal hyperplasia. These results suggest that this modality may have beneficial effects on arterial healing after angioplasty.

Angiography↗
PubMedDate not supplied

Pharmacological intervention in renal fibrosis and vascular sclerosis.

Progressive renal disease is associated with the development of fibrosing lesions not only in the glomerulus, but also in the interstitial and vascular compartments of the kidney. A growing body of work suggests that the mechanisms involved in this process are to a large extent shared by the glomerular mesangial cell, tubulointerstitial fibroblast and vascular smooth muscle cell. In this review we consider evidence that treatment strategies focused on any one of these cells are likely to be of universal benefit in the abrogation of the ongoing scarring that accompanies progressive renal disease, while at the same time reducing the progressive vascular sclerosis so often ultimately responsible for the excessive mortality seen in patients with renal failure.

Collagen↗
PubMedDate not supplied

Pirfenidone reduces in vitro rat renal fibroblast activation and mitogenesis.

BACKGROUND: Fibroblasts have been universally recognised in tubulointerstitial injury, where their presence has been shown to be a marker of disease progression. Recently, pirfenidone (PF) has been shown to both ameliorate progressive fibrosis and reduce established scarring after ureteric obstruction (UUO) in the rat, suggesting that it is a novel anti-fibrotic agent. The objective of this study was therefore to determine if these effects include down-regulation of fibroblast function. METHODS: Cortical fibroblasts were obtained from outgrowth cultures of renal tissue isolated from kidneys 3 days after UUO and constituted 100% of cells studied. Functional studies examined the effects of 20 and 200 microg/ml PF on basal serum stimulated activity. Activation was examined by western blotting for alpha smooth muscle actin (alphaSMA) and connective tissue growth factor (CTGF). Cell proliferation, collagenase activity and collagen production were determined from kinetic studies, zymography for MMP2 and [3H] proline incorporation in collagenous proteins respectively. RESULTS: Proliferation, as measured by [3H] thymidine incorporation, was reduced in dose dependent manner by 20 and 200 microg/ml PF (p<0.05; 200 vs 0 microg/ml). Likewise, 200 microg/ml PF reduced cell population growth over 5 days of culture (p<0.05 vs 0 microg/ml). PF (200 microg/ml) decreased alphaSMA and CTGF protein expression to 66+/-13 and 37+/-26% of basal levels respectively (both p<0.05 vs 0 microg/ml). Synthesis of collagen was unaffected by PF. Maximal dose of PF produced a modest reduction in MMP2 lytic activity (p=0.05). Effects of PF were independent of cell toxicity. CONCLUSIONS: Down-regulation of renal fibroblast activation and proliferation are specific actions of PF.

Actins↗
PubMedDate not supplied

Balloon expandable intraluminal vascular stent.

The percutaneous, intraluminal placement of an expandable arterial stent is a new method for reducing stenosis in atherosclerotic arteries. This method, used in conjunction with balloon angioplasty, involves the placement of metallic mesh stent at the sight of the stenosis. Use of this technique has resulted in various improvements over angioplasty alone.

Aged↗
PubMedDate not supplied

Gd-enhanced MR imaging of acute and chronic experimental demyelinating lesions.

Experimental allergic encephalomyelitis, a demyelinating disease with marked similarity to multiple sclerosis, was produced in two of 12 dogs. All dogs were studied with serial MR imaging. T1- and T2-weighted MR images were obtained both before and after IV Gd-DTPA. Multiple, new periventricular white matter demyelinating lesions were observed after each clinical episode of the disease. Like multiple sclerosis, the acute lesions of experimental allergic encephalomyelitis on T2-weighted MR images were indistinguishable from the older, more chronic lesions. However, after Gd-DTPA, there was bright paramagnetic enhancement of the acute lesions and, in one animal, no enhancement of the chronic lesions on T1-weighted MR images. At necropsy, the differences in the MR paramagnetic enhancement correlated well with the relative histologic age of the demyelinating lesions. Our results suggest that MR with Gd-DTPA may be used to differentiate acute, active demyelinating lesions from the more chronic, inactive lesions in this animal model.

Acute Disease↗
PubMedDate not supplied

Creation of atheromatous plaques in experimental animals.

Research of the dissolution of atheromatous plaques requires animal testing before any delivery system can be used on human beings. Using Flemish Giant rabbits, atheromatous plaques are created in our radiology research laboratory by a surgical air drying technique and a high cholesterol diet. Plaque development is monitored by ultrasound scanning and serial angiography.

Animals↗
PubMedDate not supplied

Effects of streptokinase in thrombolytic therapy: a radiology research project.

A radiology research project investigating the relationship between vascular endothelial injury and thrombolytic therapy using streptokinase has provided valuable data that indicates the need for a re-evaluation of such therapy and warrants further investigation in the animal laboratory. The role of the radiology research technologist in such research is explained as well.

6-Ketoprostaglandin F1 alpha↗