Development of portable long counter with two different moderator materials

A portable, light-weight long counter (LC) with small dimensions was developed. This LC consists of a (3)He thermal neutron counter, a cylindrical moderator and outer shields. It was designed to have an almost flat response in a neutron energy range of 0.4 eV to 5 MeV. The portable LC has a radius of 11 cm and a length of 39 cm. Its weight was successfully reduced to 15 kg. Polystyrene was employed instead of polyethylene for the front part of the moderator in order to increase the sensitivity to low-energy neutrons. The response function calculated using the MCNP code was consistent with the results of experiments using monoenergetic neutron calibration fields.

Photon dose mixed in monoenergetic neutron calibration fields using 7Li(p,n)7Be reaction

The ambient dose equivalents H*(10) of photons mixed in the 144, 250 and 565 keV monoenergetic neutron fields were evaluated using measurements from an NaI(Tl) detector and calculations done using the MCNP-ANT code. It was found that H*(10) of the photons produced in the target assembly dominates the dose, particularly near the target. The H*(10) of the photons produced in other materials in the field increases with the increase in distance from the target and could not be neglected at a large distance from the target. The ratios of the H*(10) of the mixed photons to that of the monoenergetic neutrons for 144, 250 and 565 keV neutron fields, were evaluated to be below 5.5, 6.9 and 1.5 %, respectively. The ratios were calculated at calibration points between 100 and 500 cm from the target.

Treatment outcomes of carotid artery stenting with two types of distal protection filter device

PURPOSE

Preventing cerebral embolism from debris produced during carotid artery stenting (CAS) is important. This study compared the treatment outcomes of CAS using two types of filter-based embolic protection devices currently in use in Japan.

MATERIALS AND METHODS

We assessed 121 consecutive cases of CAS performed with FilterWire EZ™ between July 2010 and November 2012 and 37 consecutive cases of CAS performed with the Spider FX™ between November 2012 and June 2013. A Carotid Wallstent™ was used in all cases. The incidence of positive lesions on diffusion-weighted magnetic resonance imaging (DWI) and stroke were compared between the groups.

RESULTS

Postoperative DWI-positive lesions were observed in 38 (31.4%) and 14 (37.8%) patients in the FilterWire and Spider groups, respectively. In the FilterWire group, complications were transient ischemic attacks in 3 (2.5%) patients, cerebral infarction in 2 (1.7%) patients (1 patient each with minor and major stroke), and cerebral hemorrhage due to hyperperfusion syndrome in 1 (0.8%) patient. In the Spider group, except for cerebral infarction (minor stroke) in 1 (2.7%) patient, no complications were observed. No significant differences were observed in the incidence of complications between the groups.

CONCLUSION

FilterWire EZ and Spider FX are comparable in terms of treatment outcome.

Onset Time of Ischemic Events and Antiplatelet Therapy after Intracranial Stent-assisted Coil Embolization

BACKGROUND

Stent-assisted coil embolization is effective for intracranial aneurysms, especially wide-necked aneurysms; however, the optimal antiplatelet regimens for ischemic events that develop after coil embolization have not yet been established. We aimed to determine the onset time of such postoperative ischemic events and the relationship between these events and antiplatelet therapy.

METHODS

We performed coil embolization using a vascular reconstruction stent for 43 cases of intracranial aneurysms and evaluated the incidence of postoperative ischemic events in these cases.

RESULTS

Nine patients showed postoperative ischemic events during the follow-up period (13 ± 7 months). Two patients developed cerebral infarction within 24 hours. Five patients developed transient ischemic attack within 40 days while they were receiving dual antiplatelet therapy. In addition, 1 patient showed cerebral infarction 143 days postoperatively during single antiplatelet therapy, and a case of transient visual disturbance was reported 191 days postoperatively (49 days after antiplatelet therapy had been discontinued). We increased the number of antiplatelet agents in 4 of these patients. The other 5 patients were under strict observation with dual antiplatelet therapy. All these patients were shifted to single antiplatelet therapy 3-13 months postoperatively. No recurrence of ischemic events was noted.

CONCLUSIONS

Postoperative ischemic events are most likely to occur within 40 days postoperatively. For patients with postoperative ischemic events, additional ischemic events can be prevented by increasing the number of antiplatelet agents; subsequently, they can be shifted to single antiplatelet therapy after the risk of recurrence has decreased.

Incidence of hemodynamic depression after carotid artery stenting using different self-expandable stent types

The rates of hemodynamic depression (HD) and thromboembolism were compared in 95 carotid artery stenting (CAS) procedures performed in 87 patients with severe carotid artery stenosis using self-expandable braided Elgiloy stents (Wallstent) in 52 and slotted-tube Nitinol stents (Precise) in 43 procedures. The blood pressure, pulse rate, and neurological signs were recorded at short intervals during and after CAS. All patients underwent diffusion-weighted magnetic resonance imaging within 5 days after the procedure. The incidences of hypotension, bradycardia, and both were 17.9%, 3.2%, and 11.6%, respectively. The rate of postprocedural HD was 23.1% with Wallstent and 44.2% with Precise; the difference was significant (p = 0.025). No patient manifested major cardiovascular disease after CAS. Diffusion-weighted magnetic resonance imaging revealed thromboembolism after 26.9% and 34.9% of Wallstent and Precise stent placement procedures, respectively; the difference was not significant. The type of self-expandable stent placed may affect the risk of procedural HD in patients undergoing CAS. Postprocedural HD was resolved successfully by the administration of vasopressors and by withholding antihypertensive agents.

A simplified pull-through angioplasty technique without a snare device. A technical note

The pull-through angioplasty technique allows stable wire tension and stabilization of the device during the procedure. In this technique, a guide wire is passed from one sheath to another, usually with the aid of a snare device. We describe the treatment of occlusive subclavian artery disease and lesion at the origin of the vertebral artery employing a brachiofemoral pull-through technique without using a snare device. In this technique, the guide wire is advanced from the femoral artery to the brachial artery. The guide wire is directly inserted into the sheath placed at the brachial artery. The brachial artery is compressed proximal to the point of sheath insertion to prevent bleeding. The sheath is extracted temporally and the guide wire is caught outside of the body. The sheath is then introduced again through the guide wire. We used the pull-through technique without a snare device in seven cases, and we were able to build the pull-through system in six of these cases without a snare device. This pull-through technique without a snare device is not difficult to use, and may reduce the time and cost of angioplasty procedures.

Intracranial tuberculoma in non-immunosuppressive state

The rise in the incidence of tuberculosis is generally related to human immunodeficiency virus infection. However, intracranial tuberculoma, a complication of tuberculosis considered to be a critical disease, can develop even in the absence of immunosuppressive state. Here, we describe 2 cases of intracranial tuberculoma occurring in patients with no evidence of immunosuppressive state or past history of tuberculosis. In Case 1, lesions were observed in the right lateral ventricle, with histological examination revealing granulomatous lesions. In Case 2, scattered lesions were observed in the cranium and the lung fields. In both cases, the QuantiFERON Test (QFT) was positive, and improvements were observed in the symptoms following administration of antituberculous drugs. Intracranial tuberculoma cannot be considered rare, and needs to be included in the differential diagnosis of intracranial lesions. Diagnosis can be tricky since this disease can develop in a patient in a non-immunosuppressive state or without a past history of tuberculosis. The QFT is an effective test to enable the diagnosis of tuberculomas in atypical patients.

Distal protection filter device efficacy with carotid artery stenting: comparison between a distal protection filter and a distal protection balloon

PURPOSE

This retrospective study aimed to compare the effectiveness of the embolization prevention mechanism of two types of embolic protection device (EPD)-a distal protection balloon (DPB) and a distal protection filter (DPF).

METHODS

Subjects were 164 patients scheduled to undergo carotid artery stenting: a DPB was used in 82 cases (DPB group) from April 2007 until June 2010, and a DPF was used in 82 cases (DPF group) from July 2010 to July 2011. Rates of positive findings on postoperative diffusion-weighted imaging (DWI) and stroke incidence were compared.

RESULTS

Positive postoperative DWI results were found in 34 cases in the DPB group (41.4 %), but in only 22 cases in the DPF group (26.8 %), and there was only a small significant difference within the DPF group. In the DPB group, there was one case of transient ischemic attack (TIA) (1.2 %) and four cases of brain infarction (2 minor strokes, 2 major strokes; 4.9 %), compared to the DFP group with one case of TIA (1.2 %) and no cases of minor or major strokes.

CONCLUSIONS

In this study, significantly lower rates of occurrence of DWI ischemic lesions and intraoperative embolization were associated with use of the DPF compared to the DPB.

Intraprocedural prediction of hemorrhagic cerebral hyperperfusion syndrome after carotid artery stenting

Hyperperfusion syndrome (HPS) is a rare but severe complication after carotid artery stenting (CAS). Reliable methods for predicting HPS remain to be developed. We aimed to establish a predictive value of hemorrhagic HPS after CAS. Our retrospective study included 136 consecutive patients who had undergone CAS. We determined the cerebral circulation time (CCT) by measuring the interval between the point of maximal opacification of the terminal portion of the internal carotid artery and the cortical vein. We calculated intraprocedural CCT changes (ΔCCT) by subtracting postprocedural CCT values from preprocedural CCT values. The mean ΔCCT was 0.9 ± 0.9 seconds; 3 patients (2.2%) with prolonged ΔCCT (2.7, 5.4, and 5.8 seconds) developed HPS. The cutoff time of 2.7 seconds predicted hemorrhagic HPS retrospectively with 100% sensitivity and 99% specificity. Our findings suggest that post-CAS HPS can be predicted by using the ΔCCT value obtained by intraprocedural digital subtraction angiography. Patients with a ΔCCT >2.7 seconds require careful intensive hemodynamic and neurologic monitoring after CAS.

Angiographically confirmed stent over expansion in the internal carotid artery during stenting: incidence, predictors, and outcomes

INTRODUCTION

Selection of the appropriate diameter of stent is difficult in patients with the size mismatch between the internal carotid artery (ICA) and the common carotid artery (CCA). Although stent overexpansion (SOE) in the ICA after carotid artery stenting (CAS) is suspected of producing restenosis, SOE has not been well established. We discuss its incidence, predictors, and outcomes.

METHODS

We retrospectively reviewed follow-up angiographs of 206 CAS-treated arteries in 201 patients who had undergone CAS. SOE was defined as angiographic evidence of an intimal gap between the non-stented normal and the dilated stented ICA at the distal stent edge. We also collected data on the patients' clinical status, comorbidities, and radiological and procedural data. Patients with SOE were further followed up closely by duplex ultrasound scans.

RESULTS

SOE was detected in nine of 206 CAS-treated ICAs (4.4%). Univariate analysis revealed a significant association between SOE and open-cell stents, the stent diameter (p < 0.01), pre-procedural stenosis, the ICA diameter, ICA/CCA ratio, and the ICA/stent ratio (p < 0.05). Entering these variables into a logistic regression model, open-cell stents were the only variable that significantly increased the risk for SOE (OR 2.36; 95% CI 0.99-4.60; p < 0.05). During a mean clinical follow-up of 31.1 months (range 24-39 months), none of the patients with SOE developed new neurologic ischemic symptoms, stent-edge stenosis, or in-stent restenosis.

CONCLUSION

SOE after CAS was not associated with clinical adverse effects. This study suggests that the diameter of stent should be determined by reference to the CCA diameter without respect to the ICA diameter.

Early ceasing of intra-aneurysmal contrast opacification during coil embolization in ruptured aneurysms compared with unruptured aneurysms

BACKGROUND

The difference between coil-embolized ruptured and unruptured aneurysms with respect to intra-aneurysmal thrombus formation remains to be determined.

OBJECTIVE

We examined whether there was a difference between ruptured and unruptured coil-embolized aneurysms in the rate and timing of thrombus formation in the aneurysmal sac and discuss the effect of thrombus on the treatment outcome.

METHODS

We evaluated 209 aneurysms with an aneurysmal dome smaller than 10 mm and a neck size less than 4 mm. Of these, 91 (43.5%) were ruptured. We assessed intra-aneurysmal thrombus formation by the coil-packing ratio (CPR): the percentage of coil volume occupying the aneurysmal sac. The initial CPR was defined as the CPR at which contrast influx into the sac ceased and the final CPR as that at the end of the procedure. ΔCPR was calculated as the difference between initial and final CPRs. Embolized aneurysms were evaluated on follow-up angiograms.

RESULTS

The initial CPR was significantly lower in ruptured aneurysms (P < .01), and there was not a significant difference in the final CPR between ruptured and unruptured aneurysms (P = .05). ΔCPR was significantly higher in ruptured aneurysms (P < .01). The rate of aneurysmal recanalization was significantly higher in ruptured aneurysms (P < .05). The incidence of recanalization was high in ruptured aneurysms with low initial CPR and ΔCPR values.

CONCLUSION

In ruptured aneurysms, intra-aneurysmal thrombus formation tends to occur in the earlier stages of coil embolization. In some cases, thrombus formation may inhibit dense coil packing and result in recanalization.

The constitutional t(11;22): implications for a novel mechanism responsible for gross chromosomal rearrangements

The constitutional t(11;22)(q23;q11) is the most common recurrent non-Robertsonian translocation in humans. The breakpoint sequences of both chromosomes are characterized by several hundred base pairs of palindromic AT-rich repeats (PATRRs). Similar PATRRs have also been identified at the breakpoints of other nonrecurrent translocations, suggesting that PATRR-mediated chromosomal translocation represents one of the universal pathways for gross chromosomal rearrangement in the human genome. We propose that PATRRs have the potential to form cruciform structures through intrastrand-base pairing in single-stranded DNA, creating a source of genomic instability and leading to translocations. Indeed, de novo examples of the t(11;22) are detected at a high frequency in sperm from normal healthy males. This review synthesizes recent data illustrating a novel paradigm for an apparent spermatogenesis-specific translocation mechanism. This observation has important implications pertaining to the predominantly paternal origin of de novo gross chromosomal rearrangements in humans.

Intraprocedural changes in angiographic cerebral circulation time predict cerebral blood flow after carotid artery stenting

Changes in the cerebral blood flow (CBF) are important for planning postoperative care in patients treated by carotid artery stenting (CAS). The relationship between intraprocedural changes in the angiographic cerebral circulation time (CCT) and perioperative CBF changes were retrospectively studied in 49 CAS procedures performed in 46 patients with carotid artery stenosis. The CCT, defined as the interval between the timing of maximal opacification at the terminal portion of the internal carotid artery and at the cortical vein, was determined by referring to time-density curves of data obtained from routine intraprocedural digital subtraction angiography. The intraoperative change in CCT (Delta CCT) was calculated for each of the 49 procedures. CBF studies, using dynamic perfusion computed tomography, were performed 10-2 days before and 2-4 days after CAS. Perioperative changes in the ratio of the CBF in the territory of the middle cerebral artery on the affected side to CBF on the contralateral side (%CBF) were calculated by subtracting pre- from postoperative %CBF (Delta%CBF) and the correlation between Delta CCT and Delta%CBF was evaluated. Mean CCT was shortened by 1.1 seconds from 5.3 to 4.2 seconds after CAS. Mean %CBF increased by 11.9% from 91.8% to 103.7% after the procedure. Delta CCT and Delta%CBF showed a significant positive correlation (r = 0.61, p = 0.008). Intraprocedural changes in angiographic CCT are predictive of postoperative CBF in patients with CAS.

Venting of carbon dioxide-rich fluid and hydrate formation in mid-okinawa trough backarc basin

Carbon dioxide-rich fluid bubbles, containing approximately 86 percent CO(2), 3 percent H(2)S, and 11 percent residual gas (CH(4) + H(2)), were observed to emerge from the sea floor at 1335- to 1550-m depth in the JADE hydrothermal field, mid-Okinawa Trough. Upon contact with seawater at 3.8 degrees C, gas hydrate immediately formed on the surface of the bubbles and these hydrates coalesced to form pipes standing on the sediments. Chemical composition and carbon, sulfur, and helium isotopic ratios indicate that the CO(2)-rich fluid was derived from the same magmatic source as dissolved gases in 320 degrees C hydrothermal solution emitted from a nearby black smoker chimney. The CO(2)-rich fluid phase may be separated by subsurface boiling of hydrothermal solutions or by leaching of CO(2)-rich fluid inclusion during posteruption interaction between pore water and volcanogenic sediments.

Pharmacogenetic polymorphisms in Brazilian-born, first-generation Japanese descendants

Brazil hosts the largest Japanese community outside Japan, estimated at 1.5 million individuals, one third of whom are first-generation, Brazilian-born with native Japanese parents. This large community provides a unique opportunity for comparative studies of the distribution of pharmacogenetic polymorphisms in native Japanese versus their Brazilian-born descendants. Functional polymorphisms in genes that modulate drug disposition (CYP2C9, CYP2C19 and GSTM3) or response (VKORC1) and that differ significantly in frequency in native Japanese versus Brazilians with no Japanese ancestry were selected for the present study. Healthy subjects (200 native Japanese and 126 first-generation Japanese descendants) living in agricultural colonies were enrolled. Individual DNA was genotyped using RFLP (GSTM3 A/B) or TaqMan Detection System assays (CYP2C9 2 and 3; CYP2C19 2 and 3; VKORC1 3673G>A, 5808T>G, 6853G>C, and 9041G>A). No difference was detected in the frequency of these pharmacogenetic polymorphisms between native Japanese and first-generation Japanese descendants. In contrast, significant differences in the frequency of each polymorphism were observed between native or first-generation Japanese and Brazilians with no Japanese ancestry. The VKORC1 3673G>A, 6853G>C and 9041G>A single nucleotide polymorphisms were in linkage disequilibrium in both native and first-generation Japanese living in Brazil. The striking similarity in the frequency of clinically relevant pharmacogenetic polymorphisms between Brazilian-born Japanese descendants and native Japanese suggests that the former may be recruited for clinical trials designed to generate bridging data for the Japanese population in the context of the International Conference on Harmonization.

Symptomatic inferior cavernous sinus artery aneurysm associated with cerebral arteriovenous malformation

A 50-year-old man presented with a symptomatic aneurysm arising from the right inferior cavernous sinus artery (ICSA) associated with a cerebral arteriovenous malformation (AVM) manifesting as a 3-month history of progressive right abducens nerve palsy. Cerebral angiography demonstrated a high-flow AVM and a saccular aneurysm arising from the right ICSA acting as a meningeal feeder. The symptom was thought to be attributable to aneurysmal mass effect rather than the AVM. The aneurysm was successfully treated with endovascular embolization and the symptom improved gradually. Hemodynamic stress in the ICSA may have resulted in the development of the aneurysm of the ICSA. Meningeal artery aneurysm presenting with cranial nerve palsy is extremely uncommon. The present case illustrates the need for detailed evaluation of the external carotid artery and internal carotid artery vasculature in patients with cerebral AVMs.

Carotid artery stenting for calcified lesions

BACKGROUND AND PURPOSE

Our aim was to assess the feasibility of carotid artery stent placement (CAS) for calcified lesions.

MATERIALS AND METHODS

Using embolic protection devices (EPDs), we performed 51 CAS procedures in 43 patients with severe carotid artery stenosis accompanied by plaque calcification. Before intervention, all lesions were subjected to multidetector-row CT. The arc of the circumferential plaque calcification was measured on axial source images at the site of maximal luminal stenosis, and the total volume of the plaque calcification was determined. The angiographic outcome immediately after CAS, and intra- and postoperative complications were recorded.

RESULTS

The mean arc of calcification was 201.1 +/- 72.3 degrees (range, 76-352 degrees ), and the mean of the total calcification volume was 154.9 +/- 35.4 mm(3) (range, 92-2680 mm(3)). Balloon rupture occurred in 1 procedure (2.0%) at predilation angioplasty; all 51 CAS procedures were successful without clinical adverse effects. Although there was a correlation between the arc of plaque calcification and residual stenosis (r = 0.6, P < .001), excellent dilation with residual stenosis < or =30% was achieved in all lesions. There was no correlation between the total volume of calcification and residual stenosis. None of the patients developed stroke or death within 30 days of the CAS procedure.

CONCLUSION

CAS by using EPDs to treat lesions with plaque calcification is feasible even in patients with near-total circumferential plaque calcification.

Endovascular treatment of tiny ruptured anterior communicating artery aneurysms

Introduction

Because of its high complication rate, the endovascular treatment (EVT) of anterior communicating artery (ACoA) aneurysms less than 3 mm in maximum diameter remains controversial. We evaluated EVT of tiny ruptured ACoA aneurysms with Guglielmi detachable coils (GDCs).

Methods

We treated 19 ruptured ACoA aneurysms with a maximum diameter of ≤3 mm with GDCs. The pretreatment Hunt and Hess score was grade 1 in four patients, grade 2 in six, grade 3 in six, and grade 4 in three. The patients were clinically assessed before and after treatment and with multiple angiographic follow-up studies.

Results

All EVTs were successful; there were no aneurysm perforations or any other treatment-related complications. In five patients older than 80 years the transfemoral approach was difficult, and the direct carotid approach was used. Complete and near-complete occlusion was achieved in 16 patients (84.2%) and 3 patients (15.8%), respectively. Of the 19 patients, 16 (84.2%) were followed angiographically for a median of 38.5 months (range 16–72 months). None demonstrated recanalization of the aneurysm requiring additional treatment. In 15 patients (78.9%) the final outcome was good (modified Rankin scale, mRS, score 0–2), and 3 patients (15.8%) died or suffered severe disability (mRS score 4–6). None of 18 patients who were followed clinically for a median of 39.5 months (range 17–84 months) experienced rebleeding.

Conclusion

Even tiny ruptured ACoA aneurysms can be safely treated by EVT by expert neurointerventionalists using advanced techniques.

Rebleeding after endovascular embolization of ruptured cerebral aneurysms

This study retrospectively reviewed 227 patients with ruptured solitary cerebral aneurysm who underwent endovascular embolization with detachable coils between March 1997 and March 2006 to establish the incidence of rebleeding after endovascular treatment for ruptured cerebral aneurysm and identify the risk factors. The site and size of the aneurysm, the interval between treatment and rebleeding, and the outcome were investigated in six of the 227 patients (2.6%) who rebled after treatment. Four patients had large or giant aneurysms located on the internal carotid artery at the origin of the posterior communicating artery. The interval between treatment and rebleeding was less than 1 year in four patients (mean 394.2 days). Two patients died, and the survivors had modified Rankin Scale scores of 0, 2, 3, and 4. Re-embolization was performed in four patients and no further bleeding occurred during the mean follow-up period of 1.9 years after re-treatment. Patients with giant aneurysms of the internal carotid artery are at increased risk for rebleeding. Re-treatment should be considered if there is conventional and/or magnetic resonance angiographic evidence of dome filling. Patients with ruptured cerebral aneurysms must be followed up with diagnostic imaging closely during the first 12 months post-embolization because rebleeding frequently occurs within 1 year after initial treatment. Re-embolization is safe and effective in patients with recurrent hemorrhage from aneurysms previously embolized with detachable coils.

Potassium channel openers accelerate epidermal barrier recovery

BACKGROUND

Maintenance of a competent permeability barrier in the face of external and internal stressors requires signals between the stratum corneum interface and the metabolic machinery in the underlying nucleated layers. For example, reductions in the ion gradients for Ca2+ after acute barrier disruption stimulate lamellar body (LB) secretion, a response required to restore barrier homeostasis. Although alterations in external K+ levels also regulate barrier recovery after acute insults, the mechanisms whereby K+ regulates barrier function remain unknown.

OBJECTIVES

To evaluate effects of regulators of K+ channels on barrier homeostasis in hairless mice.

METHODS

We tested a number of chemically different drugs that alter intracellular K+ levels. Results Single applications of either K+ channel openers (i.e. 1-EBIO, minoxidil, diazoxide) or the K+ ionophore, valinomycin, accelerated barrier recovery after acute insults to murine skin, paralleled by a reduction in intracellular K+ levels in cultured human keratinocytes. In contrast, applications of K+ channel blockers (i.e. gilbenclamide, dequalinium) delayed barrier recovery. Alterations in intracellular K+ regulated barrier homeostasis by either stimulating (reduced K+) or inhibiting (elevated K+) LB secretion. Finally, development of epidermal hyperplasia, a downstream consequence of barrier disruption, was also inhibited by agents that reduce intracellular K+ levels.

CONCLUSIONS

These results demonstrate that changes in K+ levels that can be presumed to occur after barrier disruption signal metabolic responses, i.e. LB secretion, which accelerates normalization of barrier function.