[Cytological study of the kidney ischemic lesions in rats]

The course of reparative regeneration after 5/6 nephrectomy and use of low-dose radiation has been studied by means of light and electron microscopy. The experiments were performed on 30 male Wistar rats. All animal procedures were conducted after approval of the protocol by the animal Studies Ethics Committee of the University of Tartu. Renal ablation was then accomplished by right nephrectomy and selective ligation of extrarenal branches of the left renal artery such that approximately 2/3 of the left kidney was infracted. All together 30 rats were randomised after the surgery and divided into two groups matched for age and body weight at week 0 and studied during 2, 4 and 8 weeks: groups I (nephrectomized, n = 15), groups II (nephrectomized and irradiated, n = 15). Left kidney of II groups rats was irradiated (60Co) 24 h after surgery in anaesthetized (Brietal) animals with 3 Gy in a single dose. As a result of experimentally induced ischemia destruction of renal corpuscles, perishing of tubular epithelial cells and and proliferation of connective tissue is followed. Reparative regeneration is based on aseptic inflammation, duration of its phases depends on the extent of organ impairment. In nephrectomized rats parallel to reparative regeneration, necrosis and deposition of calcium is found in the cortical substance. Calcium plays important role in kidney metabolism and its increased content is characteristic to degenerative changes. The experiments reveal that use of low-dose radiation does not accelerate process of reparative regeneration in rat kidney.

Experimental model for low level laser therapy on ischemic random skin flap in rats

PURPOSE: To develop an experimental model to be used in the study of low level Laser therapy on viability of random skin flap in rats. METHODS: The sample was 24 Wistar-EPM rats. The random skin flap measured 10 x 4 cm and a plastic sheet was interposed between the flap and donor site. Group 1 (control) underwent sham irradiation with diode laser (830 nm). Group 2 was submitted to laser irradiation with diode laser (830 nm). The animals were submitted to Laser therapy with 36 J/cm² energy density (72 seconds) immediately after the surgery and on the four subsequent days. The probe was usually held in contact with the skin flap surface on a point at 2.5 cm cranial from the flap base. On the seventh postoperative day, the percentage of necrotic area was measured and calculated. RESULTS: Group 1 reached an average necrotic area of 48.86%, Group 2 - 23.14%. After the statistic analysis, compared with the control group, Group 2 showed a statistically significant increase in survival area (p<0.001). CONCLUSION: The experimental model proved to be reliable to be used in the study of effects of low level laser therapy in random skin flap in rats.

Low-dose irradiation promotes tissue revascularization through VEGF release from mast cells and MMP-9-mediated progenitor cell mobilization

Mast cells accumulate in tissues undergoing angiogenesis during tumor growth, wound healing, and tissue repair. Mast cells can secrete angiogenic factors such as vascular endothelial growth factor (VEGF). Ionizing irradiation has also been shown to have angiogenic potential in malignant and nonmalignant diseases. We observed that low-dose irradiation fosters mast cell–dependent vascular regeneration in a limb ischemia model. Irradiation promoted VEGF production by mast cells in a matrix metalloproteinase-9 (MMP-9)–dependent manner. Irradiation, through MMP-9 up-regulated by VEGF in stromal and endothelial cells, induced the release of Kit-ligand (KitL). Irradiation-induced VEGF promoted migration of mast cells from the bone marrow to the ischemic site. Irradiation-mediated release of KitL and VEGF was impaired in MMP-9–deficient mice, resulting in a reduced number of tissue mast cells and delayed vessel formation in the ischemic limb. Irradiation-induced vasculogenesis was abrogated in mice deficient in mast cells (steel mutant, Sl/Sl^d mice) and in mice in which the VEGF pathway was blocked. Irradiation did not induce progenitor mobilization in Sl/Sl^d mice. We conclude that increased recruitment and activation of mast cells following irradiation alters the ischemic microenvironment and promotes vascular regeneration in an ischemia model. These data show a novel mechanism of neovascularization and suggest that low-dose irradiation may be used for therapeutic angiogenesis to augment vasculogenesis in ischemic tissues.

Endovascular gamma irradiation for the prevention restenosis after angioplasty of femoropopliteal de novo stenoses

The purpose of this study was to investigate the effectiveness and detect side effects of centered, overlapped endovascular gamma irradiation after angioplasty of de novo femoropopliteal stenoses. Thirty patients (age 65.3+/-9.2 years) with arterial occlusive disease were prospectively enrolled to receive endovascular gamma irradiation (192-iridium, 14 Gy centered at 2 mm vessel wall) immediately after percutaneous transluminal angioplasty (PTA) of femoropopliteal stenoses. Irradiation overlapped dilatation by 1-2 cm at each end. Follow-up involved angiography after 12 months; duplex sonography; and interviews before and after PTA and at 1, 6, and 12 months follow-up. PTA and centered endovascular irradiation were performed successfully in all patients. Three thromboembolic complications occurred during irradiation. Angiographic and clinical follow-up was possible in 28 patients. The angiographic degree of stenosis was 73.8%+/-16.3% before and 3.6%+/-23.5% after PTA and was 3.5%+/-43.7% at the 1-year follow-up. Restenosis (>50%) of the target lesion developed in three patients (10.7%) and edge stenoses (>30%) in nine patients (32.1%). An aneurysm of the irradiated segment in one patient was treated by stenting. The rate of retreatment was 17.9%. The vessel diameter after endovascular gamma irradiation and PTA of femoropopliteal stenoses remained stable. Restenosis, induction of edge stenoses, and aneurysm were reasons for reinterventions.

Endovascular Brachytherapy: Effect on Acute Inflammatory Response after Percutaneous Femoropopliteal Arterial Interventions

PURPOSE

To investigate whether endovascular brachytherapy diminishes vascular inflammation in response to femoropopliteal percutaneous transluminal angioplasty (PTA) or stent implantation in two double-blind randomized-controlled trials.

MATERIALS AND METHODS

Forty-seven consecutive patients from two double-blind randomized-controlled trials were studied. Patients either underwent femoropopliteal PTA with endovascular gamma irradiation (n = 8) or placebo irradiation (n = 7) or underwent PTA and stent implantation with brachytherapy (n = 15) or placebo irradiation (n = 17). High-sensitivity C-reactive protein (CRP), serum amyloid A (SAA), and fibrinogen levels were measured at baseline and 8, 24, and 48 hours after the intervention. The change of acute phase parameters from baseline to 48 hours after intervention indicated the extent of the inflammatory response and was compared between patients undergoing brachytherapy and those undergoing placebo irradiation. Fisher exact test was used for comparison of categorical data, and nonparametric statistical methods were applied for analysis of continuous data (Mann-Whitney U tests for unpaired data and Friedman analysis for repetitive measurements).

RESULTS

Median patient age was 70 years (interquartile range, 56-74 years); 33 (70%) patients were men and 14 (30%) were women. Clinical characteristics and baseline values of acute phase parameters were similar between groups. A statistically significant increase in CRP, SAA, and fibrinogen values was observed after PTA and stent implantation, both in the patients who underwent brachytherapy and in those who underwent placebo irradiation. Compared with placebo irradiation, however, brachytherapy did not significantly reduce any acute phase parameter from baseline to 8, 24, or 48 hours after the intervention (P >.05 for all comparisons).

CONCLUSION

Endovascular brachytherapy did not diminish early vascular inflammation in response to PTA or stent implantation and even induced a trend toward an increased inflammatory response.

Effects of diode laser therapy on blood flow in axial pattern flaps in the rat model

Axial pattern skin flaps are a very important reparative tool for the plastic and reconstructive surgeon in the reconstruction of tissue defects. From whatever unfortunate reason, part or all of such flaps occasionally suffers from irreversible ischaemia with loss of the flap. Infrared diode laser therapy has been shown to improve local and systemic circulation. The present study was designed to assess the effect of an 830 nm diode laser (power density, 18.5 W/cm(2), energy density 185 J/cm(2)) on the blood flow of axial pattern flaps in the rat model and their survival, compared with unirradiated controls. The flaps were raised in all animals ( n=40), and blood flow assessed with laser speckle flowmetry (LSF). In the experimental groups (3 groups, n=10 per group), the flaps were irradiated either directly over the dominant feeder vessel (iliolumbar artery), at the proximal end or at the distal end of the flap itself and blood flow assessed during irradiation. Flowmetry was performed again in all animals at 5 and 10 min postirradiation, and the flaps sutured back in position. The unirradiated controls were handled in exactly the same way, but the laser was not activated. The survival rate of the flaps was assessed on the fifth postoperative day. LSF demonstrated significant increased blood flow in the flaps at 5 and 10 min postirradiation in all experimental groups compared with the control animals. At five days postirradiation, there was significantly better survival of the flaps in all the experimental groups compared with the controls ( p<0.01), but no significant difference was seen between any of the experimental groups. We conclude that laser therapy increases the blood flow and perfusion of transferred flaps, and that this has significant effects on the survival of the flaps. One possible mechanism of modulation of the autonomic nervous system is discussed.

Preliminary observations on the need for control angiography after peripheral endovascular brachytherapy using a centering balloon

PURPOSE

To examine the need for completion angiography after endovascular femoropopliteal brachytherapy using a centering catheter.

METHODS

Nine consecutive patients (7 men; mean age 68 years, range 53-79) were enrolled in a double-blinded multicenter randomized trial of endovascular brachytherapy after femoropopliteal balloon angioplasty. All patients underwent postdilation angiography, after which the centering catheter was placed in the dilated segment. The patients were randomized and transferred to the radiotherapy unit; the centering catheter was inflated only in patients randomized to receive brachytherapy (18 Gy of gamma radiation delivered to the target site 2 mm from an iridium-192 source axis). Because the local ethics committee required angiography after any interventional procedure (not stipulated in the study protocol), our patients were taken back to the angiosuite for angiography.

RESULTS

There were no complications of angioplasty or centering catheter introduction. In the 5 patients randomized to brachytherapy, the median inflation time of the centering catheter was 12.1 minutes (range 9.1-13.3). The completion angiogram following brachytherapy showed peripheral embolization in 2 patients and lesion recoil that required redilation in another; all the complications were confined to the treatment group.

CONCLUSIONS

Three of 5 patients who received brachytherapy via a centering catheter demonstrated sequelae on postradiation angiography. Therefore, as in any other peripheral vascular intervention, completion angiography after brachytherapy seems to be essential in preventing delayed diagnosis of procedural complications.

The influence of helium-neon laser irradiation on the viability of skin flaps in the rat

Low energy helium-neon (He-Ne) laser irradiation has been shown to induce various therapeutic effects. We investigated its effect on the viability of skin flaps in the rat. Thirty rats underwent skin flap elevation and were then divided into three equal groups. Group I (control) was not irradiated. Groups II and III were irradiated for 5 days postoperatively, Group II to the transition zone (between the live and expected necrotic areas) and Group III to the transitional and distal zones; total energy, 2.9 J/cm(2)for each rat. Ten days after the last treatment larger surviving areas were demonstrated macroscopically in Groups II and III (P< 0.01 and 0.001, respectively). Histological examination showed tremendous proliferation of capillaries (P</= 0.05) and fibroblasts in the responsive irradiated areas. In conclusion, postoperative low-energy (2.9 J/cm(2)) He-Ne laser irradiation of the expected ischaemic zone of the rat flap can enlarge the surviving area. Irradiation of the whole expected ischaemic zone seems to be superior to irradiating the transition zone alone.

[The influence of laser radiation on blood flow in patients with ischemia of the lower limbs (based on the analysis of the hyperemia reactive test)]

The aim of this paper was to assess the influence of low power infra red laser radiation on blood flow in patients with atherosclerotic disease of the lower limbs. The investigations were based on the hyperemic reactive test and the ankle/brachial pressure index. Analysis of the hyperemic reactive test allows to evaluate microcirculation mechanisms. The results obtained indicate that treatment of low power laser radiation allows to improve microcirculation mechanisms and blood flow in the lower limbs.

[Endovascular radioprevention of intimal hyperplasia after percutaneous transluminal angioplasty of peripheral blood vessels]

The prognosis of interventionally treated arterial occlusive vessel disease in peripheral arteries is not significantly better with the use of stents than with percutaneous transluminar angioplasty. The rate of restenosis or reocclusion in dilated or recanalized and stented peripheral arteries is reported as up to 40%, depending on location and author. In the early phase thrombotic processes are responsible which then demonstrate histologically confirmed intimal hyperplasia. On the basis of many years of radiotherapy experience in the treatment of benign hyperplastic tissue alterations, brachytherapy could be introduced as a method for prophylaxis of vessel restenoses. The early difficulties with this method were due to the inadequacies of the equipment. The development of small radiation sources with high specific activity now enables these target volumes to be reached. The clinical experience so far indicates high efficiency of this method. It can be expected that the range of indications for adjuvant endoluminal irradiation will broaden in the future.

[Intervention and clinical aspects combined with endovascular irradiation of intimal hyperplasia of the vascular system]

After implantation of stents in femoropopliteal arteries we found restenosis or occlusions by intimal hyperplasia in up to 40% especially in the hunter's channel. Repeated balloon angioplasty and prophylactic endovascular radiotherapy with a surface dose of 12 Gy in the vessel wall using an iridium 192 source in the same investigational session is a new technique to reduce or eliminate further recurrence. All 18 patients had developed recurrent stenoses or occlusions 6-8 months after original stent implantations. The patients have not redeveloped recurrent obstructions after this treatment, which up to date showed no short term or long term complications. We conclude that the encouraging results of this pilot study justify further randomized trials.

[Effect of laser biostimulation on leg blood flow in the course of arteriosclerosis]

Blood flow pattern (maximum moment velocity, mean velocity, artery diameter and minute flow) in the superficial femoral artery and in the foot artery was evaluated in 30 patients, subjected to laser biostimulation for symptoms of atherosclerotic ischemia of the lower limbs. The blood flow examination was performed before the treatment and immediately afterwards (20 procedures) and 6 months following the therapy. It was found that laser biostimulation had a favorable effect on the blood flow pattern, particularly in the initial stage of ischemia (Io), and may be a useful method of medical treatment in atherosclerotic ischemia of the lower limbs.

[The microcirculation of patients with arterial ischemia of the lower extremities during laser therapy]

Microcirculation in the patient's foot skin with different stages of arterial ischemia, was examined with the aid of TV-capillaroscopy, laser dopplerography, polarography of transcutaneous oxygen tension. The effect of semiconductor laser (wave length 0.98 mcm) on microcirculation system was studied. The dependence of capillary blood flow on the transcutaneous oxygen tension was determined. The laser therapy proved to be successful in the patients with the II and III stages of arterial ischemia.

[Interventional angiology in the area of the thigh. Percutaneous balloon dilatation, new procedures of recanalization, stents]

The major technique of interventional angiology of the arteries of the thigh is percutaneous balloon dilatation (angioplasty). In the case of short stenoses and occlusions, the primary results and long-term success of these techniques are very good. In order to be able to successfully treat long, highly calcified, eccentric and fresh lesions using the percutaneous approach, numerous new procedures have been developed. These include local fibrinolysis, aspiration of thromboembolic material, ablation of atherosclerotic plaques using an endovascular knife, the drilling open of occlusions, the use of the laser, and implantation of vascular endoprostheses.

[Arterial macrocirculation following ultraviolet irradiation of venous blood in patients with arterial occlusive disease]

The influence on macrocirculatory parameters by ultraviolet irradiation of autologous venous blood was controlled in 5 patients. The ultraviolet irradiation did not show any positive effect on different sizes of blood supply. Therefore, as a conclusion the recommendation is given in every case at first to attempt the possibilities of a reconstruction of the arterial vascular system before the use of this therapy.

[Effect of helium-neon laser radiation on restoration of the structure of the microcirculatory bed and neurocytes of the small intestine following experimental ischemia]

Influence of helium-neon laser lg-75 rays on the microcirculatory bed and neurocytes of the small intestine after its experimental ischemia has been studied. When a normal small intestine is radiated, dilatation of the luminal diameter is observed in all links of the microcirculatory bed (MCB) and also hypertrophy of neurocytes, when phenomena of distrophic processes are absent. In 30 days after 3-hours' ischemia of the intestinal loop and its successive radiation, spasm of arterial and dilatation of the venous link of MCB is registered; they normalize by the 45th day. In the control, after ischemia (without radiation) in 45 days venous plethora of the vessels in the intermuscular plexus of the intestinal wall is kept. In the nervous elements of the muscular-intestinal plexus at early stages of the experiment against the background of ischemia reactive and distrophic changes appear. By the 30th day after radiation, the volume of neurocytic bodies increases, processes grow out, nuclear-cytoplasmic index increases. Nonspecific character of the laser rays is supposed; their effect is realised via regional microvascular and nervous formations.