Pretreatment with continuous-wave ultraviolet irradiation to prevent the development of delayed vasospasm in the rabbit common carotid artery model

PPP2R2C as a candidate gene of a temperament and character trait-based endophenotype of ADHD

There are several lines of evidence that the 4p16 region is a candidate locus of both attention-deficit/hyperactivity disorder (ADHD) and bipolar disorder. None of the harbored candidate genes of this region were hitherto shown to be associated with ADHD despite promising functionality. One of the most promising candidate genes in this region is protein phosphatase 2, regulatory subunit B, gamma (PPP2R2C), which, however, thus far has not been assessed for a potential association with ADHD. A total of 513 in- and outpatients affected with adult ADHD and 536 controls as well as 170 nuclear families with 249 children affected with ADHD were genotyped for 35 SNPs, which tagged the promoter region, the 5' and 3' UTRs, and the exons of the PPP2R2C. Two independent samples provided evidence that the major G allele of rs16838844 increases risk toward ADHD. Allelic variations of PPP2R2C rs16838698 on the other hand might be associated with a variety of personality traits. There is evidence that allelic variation in PPP2R2C may be associated with a variety of personality traits and ADHD per se. Nevertheless, as all those conditions are comorbid, PPP2R2C might reflect a common underlying neurobiological risk factor.

Hypercholesterolemia increases vasospasm resulting from basilar artery subarachnoid hemorrhage in rabbits which is attenuated by Vitamin E

BACKGROUND

Aneurysm rupture results in subarachnoid hemorrhage (SAH) with subsequent vasospasm in the cerebral and cerebellar major arteries. In recent years, there has been increasing evidence that hypercholesterolemia plays a role in the pathology of SAH. It is known that hypercholesterolemia is one of the major risk factors for the development of atherosclerosis. Among the factors that have been found to retard the development of atherosclerosis is the intake of a sufficient amount of Vitamin E. An inverse association between serum Vitamin E and coronary heart disease mortality has been demonstrated in epidemiologic studies. Therefore, we tested, in an established model of enhanced cholesterol feed in rabbits, the effects of hypercholesterolemia on vasospasm after SAH by using computed tomography (CT) angiograms of the rabbit basilar artery; in addition, we tested the effects of Vitamin E on these conditions, which have not been studied up to now.

METHODS

In this study rabbits were divided into 3 major groups: control, cholesterol fed, and cholesterol + Vitamin E fed. Hypercholesterolemia was induced by a 2% cholesterol-containing diet. Three rabbit groups were fed rabbit diet; one group was fed a diet that also contained 2% cholesterol and another group was fed a diet containing 2% cholesterol and they received i.m. injections of 50 mg/kg of Vitamin E. After 8 weeks, SAH was induced by the double-hemorrhage method and distilled water was injected into cisterna magna. Blood was taken to measure serum cholesterol and Vitamin E levels. Basilar artery samples were taken for microscopic examination. CT angiography and measurement of basilar artery diameter were performed at days 0 and 3 after SAH.

RESULTS

Two percent cholesterol diet supplementation for 8 weeks resulted in a significant increase in serum cholesterol levels. Light microscopic analysis of basilar artery of hypercholesterolemic rabbits showed disturbances in the subendothelial and medial layers, degeneration of elastic fibers in the medial layer from endothelial cell desquamation, and a reduction of waves in the endothelial layer. However, the cholesterol + Vitamin E group did not exhibit these changes. The mean diameter of the basilar artery after SAH induction in the cholesterol-treated group was decreased 47% compared with the mean diameter of the control group. This value was less affected in cholesterol + Vitamin E-treated rabbits, which decreased 18% compared with the mean diameter of the control group.

CONCLUSIONS

Hypercholesterolemia-related changes in the basilar artery aggravate vasospasm after SAH. Adding Vitamin E to cholesterol-treated rabbits decreased the degree of vasospasm following SAH in the rabbit basilar artery SAH model. We suggest that Vitamin E supplements and a low cholesterol diet may potentially diminish SAH complicated by vasospasm in high-risk patients.

Feasibility of photocrosslinkable chitosan as an embolization material for aneurysms. Biological reaction after aneurysm embolization

SUMMARY

The purpose of this study was to evaluate the feasibility of photocrosslinkable chitosan as an embolization material for aneurysms. Three experimental aneurysms were created in three Japanese white rabbits. All of the aneurysms were packed with chitosan hydrogel. Histopathologic data were analyzed on two, seven, and 30 days after embolization. Unorganized clots and minimal inflammation around the applied chitosan hydrogel were observed two days after implantation. After seven days, the chitosan was reduced and inflammatory response appeared. At 30 days, most of the aneurysm lumen was replaced with inflammatory cells, and the remaining chitosan was not observed. Severe complications such as anaphylaxis did not occur after the embolization with the chitosan. These results suggest that photocrosslinkable chitosan might be a candidate for an embolization material for endovascular treatment of cerebral aneurysms.

Long-term effects of UV light on contractility of rat arteries in vivo

Several studies have shown that UV irradiation may be effective for preventing vascular restenosis or vasopasm. However, the long-term effects of UV light on the physiological properties of vessels such as arterial tension have not been elucidated. We therefore studied the long-term effects of UV using rat carotid arteries treated with UV-B light (wavelength = 313 nm, total energy = 14 mJ/mm2). The animals were sacrificed at 1, 7 and 14 days after UV light exposure, and the carotid arteries were studied by light microscopy and the contractile responses of isolated arterial rings were recorded under isometric tension. UV treatment had induced a substantial loss of smooth muscle cells (SMC) along the entire circumference of the media on days 7 and 14, whereas loss of SMC on day 1 was negligible. Contractile responses of arteries that had been exposed to UV light were significantly reduced on days, 1, 7 and 14. The susceptibility of UV-treated arteries to phenylephrine and prostaglandin F2 alpha was significantly decreased on days 1 and 7, but decreased susceptibility was not seen on day 14. Acetylcholine-induced relaxations were not altered by UV treatment. These results suggest that the long-term effect of UV light is an attenuation of smooth muscle contractility without impairment of endothelial function.

Vasospasm model of a rabbit common carotid artery for endovascular research

RATIONALE AND OBJECTIVES

Endovascular treatments such as balloon angioplasty and injection of vasodilators play an important role in cerebral vasospasm refractory to first-line therapies. Experimental studies with intracranial arteries of animals have some limitations, however, because in most cases endovascular devices are too large and inflexible to catheterize these arteries. The purpose of this study was to document the natural course of a vasospasm model using a rabbit common carotid artery.

MATERIALS AND METHODS

The common carotid arteries of 24 New Zealand white rabbits were used. Autologous blood was placed around the isolated artery and kept in place with a silicone cuff. The time course of vasoconstriction after blood clot placement was examined with angiography and with histopathologic evaluation.

RESULTS

Angiographic vasoconstriction was prominent on day 2, less obvious on day 9, and absent on day 30. At histopathologic evaluation, folding of the endothelial surface, corrugation of the internal elastic lamina, and thickening of the arterial wall were observed in the group with blood clot placements around the artery on day 2 and were nearly absent on day 30.

CONCLUSION

This model may be used for the study of endovascular treatments of vasospasm.

Inhibition of experimental vasospasm by pretreatment with ultraviolet light irradiation in a rat femoral artery model

OBJECTIVE

Chronic cerebral vasospasm is resistant to conventional treatments despite recent advances in treatment modalities. We studied the preventive effect of ultraviolet (UV) irradiation on development of vasospasm and its mechanism in a rat femoral artery model.

METHODS

The rat femoral artery model for vasospasm was used in this investigation (n = 108). The femoral arteries were divided into four groups: empty and no irradiation (control), UV irradiation (UV group), blood placement (VS group), and blood placement after UV irradiation (VS + UV group). Luminal area was measured, and smooth muscle cell counts in the medial layer of the vessel wall were obtained. An immunohistochemical study was performed with cross sections of fixed femoral arteries at 12 hours and 1, 3, 5, 7, and 49 days after blood placement. The rings of femoral arteries on Day 7 were subjected to pharmacological study.

RESULTS

Pretreatment with UV irradiation (VS + UV group) resulted not only in significant inhibition of chronic vasospasm but also in a significant decrease in smooth muscle cells compared with the VS group on Days 5 and 7. The UV-treated arteries (UV and VS + UV groups) exhibited a significant number of Bax- and Bcl-2-positive cells on Days 5 and 7, but few CPP-32 positive cells were observed at the same time points. In the pharmacological study, contractile response to KCI or phenylephrine was reduced significantly in the UV-treated arteries.

CONCLUSION

These results imply that UV irradiation prevents chronic vasospasm and suggest that UV-induced cell death plays an important role in the preventive effect without causing complications during the chronic period.

Photochemical oxygen consumption, oxygen evolution and spectral changes during UVA irradiation of EMT6 spheroids

Remarkable rates of oxygen consumption are observed via microelectrode measurements immediately upon the onset of 325 nm irradiation of multicell tumor spheroids. Consumption is irradiance dependent over the range 20-200 mW cm-2, and its magnitude is comparable to that observed previously in the same system using exogenous photosensitizers. Oscillations in the oxygen concentrations suggest that oxygen is also being evolved during irradiation. Oxygen evolution is likely the result of enzymatic dissociation of hydrogen peroxide, which is formed through UV-induced photochemistry. Irradiation of spheroids at 442 and at 514 nm produces a much more modest but detectable oxygen consumption. The dynamics of oxygen concentration changes are quite different at these wavelengths, suggesting a different photochemical mechanism. In these cases, initial oxygen depletion is followed immediately by a more gradual, monotonic increase in the oxygen concentration, consistent with irreversible photobleaching. No oscillations in the oxygen concentration are detectable. At 662 nm, no oxygen consumption was observed over the range of irradiances studied. Fluorescence spectra of cells prior to irradiation include contributions from anthranilic acid and reduced nicotinamide adenine dinucleotide (NADH). During 325 nm irradiation, anthranilic acid is rapidly and irreversibly bleached, while NADH emission undergoes only modest reduction.