Gbetagamma-mediated regulation of Golgi organization is through the direct activation of protein kinase D.

We have shown previously that the betagamma subunits of the heterotrimeric G proteins regulate the organization of the pericentriolarly localized Golgi stacks. In this report, evidence is presented that the downstream target of Gbetagamma is protein kinase D (PKD), an isoform of protein kinase C. PKD, unlike other members of this class of serine/threonine kinases, contains a pleckstrin homology (PH) domain. Our results demonstrate that Gbetagamma directly activates PKD by interacting with its PH domain. Inhibition of PKD activity through the use of pharmacological agents, synthetic peptide substrates, and, more specifically, the PH domain of PKD prevents Gbetagamma-mediated Golgi breakdown. Our findings suggest a possible mechanism by which the direct interaction of Gbetagamma with PKD regulates the dynamics of Golgi membranes and protein secretion.

Interventional cardiovascular therapy by laser and thermal angioplasty.

The advent of balloon angioplasty as a clinical device crystallized the concept of nonsurgical revascularization. The problems of restenosis, diffuse disease, and total occlusions persist despite the demonstrated efficacy of balloon angioplasty. During the past 5 years, a variety of laser devices and catheter designs have demonstrated usefulness in the treatment of peripheral vascular disease. Initial success rates of 70-90% have been reported in occluded femoropopliteal arteries. Further clinical trials are warranted to compare the relative efficacy of these devices with each other and conventional therapies. Thermal ablative devices have not yet shown great promise for treatment of coronary disease. Modified versions of these devices as well as nonthermally acting excimer lasers are promising as clinical tools for enhancing our ability to nonsurgically revascularize patients, and trials with these devices are now underway.

Percutaneous excimer laser angioplasty of aortocoronary saphenous vein grafts.

Percutaneous coronary excimer laser angioplasty was successfully performed in two patients. An 85 year old woman with a 99% stenosis in a vein graft to a posterior descending artery had the stenosis reduced to 30% with laser angioplasty. Subsequent balloon angioplasty reduced the stenosis further to 20%. A second patient, a man aged 50 years, had multiple previous balloon angioplasties and stent implantation with two subsequent percutaneous atherectomies. Laser angioplasty of the vein graft to the obtuse marginal branch reduced the first of three sequential lesions from 60% to 40%, the second lesion from 90% to none and the third from 60% to 20% without the need for balloon angioplasty. Both procedures were well tolerated without chest pain, burning, vascular perforation or thrombus formation. These cases demonstrate the feasibility of safely performing percutaneous coronary excimer laser angioplasty. Additional studies are indicated to determine the clinical role and potential benefits of this procedure in relation to established procedures and other experimental devices.

Percutaneous excimer-laser and excimer-laser-assisted angioplasty of the lower extremities: results of initial clinical trial.

Percutaneous peripheral excimer-laser angioplasty at 308 nm was used for treatment of 30 patients with peripheral vascular disease. Twenty-eight patients underwent laser-assisted balloon angioplasty, and two patients underwent laser angioplasty alone. Acute angiographic and clinical success was achieved in 24 of 31 (77%) femoropopliteal stenoses and occlusions. Seven of nine (78%) stenoses, six of seven (86%) short (0-5 cm) occlusions, seven of eight (88%) medium-length (6-10 cm) occlusions, three of four (75%) long (11-15 cm) occlusions, and one of three (33%) extreme (greater than 15 cm) occlusions were successfully treated. Inability to treat total occlusions was in each case related to a failure to maintain coaxial position and subintimal passage of the fiber. These cases demonstrate the feasibility of safely performing percutaneous peripheral excimer-laser or excimer-laser-assisted angioplasty. The overall frequency of restenosis after a mean follow-up period of 9.1 months was 29%. The data suggest that these procedures may be useful for the treatment of peripheral vascular disease in selected patients.

Pulsed laser angioplasty: wavelength power and energy dependencies relevant to clinical application.

Despite the theoretical advantages of submicrosecond pulsing for clinical laser angioplasty systems, the optimal laser parameters for clinical application are undefined. Further, the enormous peak powers achieved by submicrosecond pulses destroy available fiberoptics. We irradiated 797 segments of cadaver atherosclerotic aorta with nanosecond pulses at 266, 308, 355, 532, and 1064 nanometers. Effective cutting occurred at lower energy fluences in the ultraviolet than in the visible or infrared. For 308 nanometers, at any energy density, number of pulses to perforation was relatively independent of power density. Therefore, long-pulse ultraviolet wavelengths which could be transmitted through fiberoptics were identified as well suited for a clinical, submicrosecond pulsed laser angioplasty system.

Effects of hematoporphyrin derivative and photodynamic therapy on atherosclerotic rabbits.

This study was performed to demonstrate selective uptake of hematoporphyrin derivative (HPD) within actively developing atheroma, to localize the site of uptake of HPD within the atheroma, and to determine the potential for photodynamic therapy (PDT) of atherosclerosis in the rabbit model. Fifteen rabbits were rendered atherosclerotic. Five rabbits received neither HPD nor PDT and 2 rabbits received HPD, 10 mg/kg intravenously, without subsequent irradiation. Eight other rabbits received 5 to 20 mg of HPD intravenously and subsequent intravascular 636-nm laser radiation to either the thoracic aorta or the aortic arch. A total of 32 to 288 J of laser energy was delivered through a 300-mu quartz fiber. All rabbits that received in vivo HPD had red fluorescence of their aortas when placed under ultraviolet light. The pattern of fluorescence corresponded precisely to the pattern of atheroma. In segments that received PDT, light microscopic examination revealed an accumulation of smooth muscle cells at the intimal surface. Fluorescence microscopy revealed a diminishing concentration gradient of HPD from intimal surface layers towards the media. Assessment of treated thoracic aortic segments revealed quantitative and qualitative differences compared with control segments. In the arch-treated segments, however, no changes were seen. It is concluded that HPD localizes within rabbit atheroma, can be detected by fluorescence and is deposited in a diminishing concentration gradient from lumen toward media. Irradiation with 636-nm light may induce qualitative and quantitative changes in atheroma.