Mechanical properties of a bioabsorbable nerve guide tube for long nerve defects.

The mechanical properties of nerve guide tubes must be taken into consideration when they are being developed. We previously reported the feasibility of using 50:50 tubes in a canine 40mm peroneal nerve defect model, where 50:50 represents the proportion of poly(L-lactic) acid (PLLA) and polyglycolic acid (PGA). The aim of the current study was to show that 50:50 tubes have suitable mechanical properties for repairing long nerve defects. Four types of nerve guide tubes made with PLLA to PGA fiber ratios of 100:0 (i.e. 100% PLLA) (100:0 tube), 50:50 (50:50 tube), 10:90 (10:90 tube), and 0:100 (0:100 tube) were designed and created using a tubular braiding machine. Their mechanical properties were examined in vitro (up to 16 weeks). In compression testing, 50:50 tubes had the highest normalized force value, followed in order by the 100:0, 10:90, and 0:100 tubes up to 8 weeks after immersion. From the point of view of biomechanics and bioresorbability, out of the 4 tube types tested, 50:50 tubes appeared to have the optimal mechanical properties for longer nerve defects.

Phosphorus flame retardants in indoor dust and their relation to asthma and allergies of inhabitants.

Organophosphate esters are used as additives in flame retardants and plasticizers, and they are ubiquitous in the indoor environment. Phosphorus flame retardants (PFRs) are present in residential dust, but few epidemiological studies have assessed their impact on human health. We measured the levels of 11 PFRs in indoor floor dust and multi-surface dust in 182 single-family dwellings in Japan. We evaluated their correlations with asthma and allergies of the inhabitants. Tris(2-butoxyethyl) phosphate was detected in all samples (median value: 580 µg/g in floor dust, 111 µg/g in multi-surface dust). Tris(2-chloro-iso-propyl) phosphate (TCIPP) was detected at 8.69 µg/g in floor dust and 25.8 µg/g in multi-surface dust. After adjustment for potential confounders, significant associations were found between the prevalence of atopic dermatitis and the presence of TCIPP and tris(1,3-dichloro-2-propyl) phosphate in floor dust [per log10 -unit, odds ratio (OR): 2.43 and 1.84, respectively]. Tributyl phosphate was significantly associated with the prevalence of asthma (OR: 2.85 in floor dust, 5.34 in multi-surface dust) and allergic rhinitis (OR: 2.55 in multi-surface dust). PFR levels in Japan were high compared with values reported previously for Europe, Asia-Pacific, and the USA. Higher levels of PFRs in house dust were related to the inhabitants' health status.

Relationships between mite allergen levels, mold concentrations, and sick building syndrome symptoms in newly built dwellings in Japan.

UNLABELLED: This study investigated the possible relationships between exposures to mite allergen and airborne fungi with sick building syndrome (SBS) symptoms for residents living in newly built dwellings. We randomly sampled 5709 newly built dwellings in six prefectures from northern to southern Japan. A total of 1479 residents in 425 households participated in the study by completing questionnaire surveys and agreeing to environmental monitoring for mite allergen (Der 1), airborne fungi, aldehydes, and volatile organic compounds. Stepwise logistic regression analyses adjusted for confounders were used to obtain odds ratios (OR) of mite allergen and fungi for SBS symptoms. Der 1 had a significantly high OR for nose symptoms. Rhodotorula had a significantly high OR for any symptoms, and Aspergillus had significantly high OR for eye symptoms. However, the total colony-forming units had a significantly low OR for throat and respiratory symptoms. Eurotium had a significantly low OR for skin symptoms. In conclusion, dust-mite allergen levels and indoor airborne Rhodotorula and Aspergillus concentrations may result in SBS symptoms in newly built dwellings. PRACTICAL IMPLICATIONS: Various factors can cause sick building syndrome symptoms. This study focused on biologic factors such as dust-mite allergen and airborne fungi in newly built dwellings in Japan. Dust-mite allergen levels were significantly associated with higher rates of nose symptoms, airborne Rhodotorula concentrations were significantly associated with higher rates of any symptoms, and Aspergillus concentrations were significantly associated with higher rates of eye symptoms. Measures should be taken to reduce mite allergen levels and fungal concentrations in these dwellings.

Regional differences in residential environments and the association of dwellings and residential factors with the sick house syndrome: a nationwide cross-sectional questionnaire study in Japan.

UNLABELLED: This study was conducted to clarify regional differences in residential factors and the association of those factors with dwellings having sick house syndrome (SHS) problems. The survey was conducted in six areas of northern and southern Japan. In terms of regional differences, dampness was not as severe in the dwellings in Sapporo as compared with that in areas in the south. SHS was defined using five categories of nasal, throat and respiratory, skin and general symptoms, which appeared frequently or not frequently and improved upon leaving the home. The dampness index was estimated by the sum of the presence of several indicators: condensation on the window panes and/or wall, visible mold growth, moldy odor, slow-drying wet towels in the bathroom, and water leakage. The dwellings where inhabitants showed any symptoms of SHS comprised 3.7% of all surveyed dwellings. We found significant associations between SHS and dampness index, odors, and stuffiness of the air. For dampness, the adjusted odds ratio (OR) increased with increased dampness index, adjusting for the age of the house, pets indoors, stuffiness of the air, and odors. These results showed an increased risk when several dampness indicators appeared simultaneously. PRACTICAL IMPLICATIONS: To evaluate the associations of residential environments and Sick House Syndrome (SHS), this cross-sectional questionnaire study was conducted on 2297 dwellings in six areas in Japan from 2003 to 2004. The dwellings where inhabitants showed any of nasal, throat and respiratory, skin and general symptoms comprised 3.7% of all surveyed dwellings, and an increased risk for SHS was found when several dampness indicators, 'condensation', 'visible mold growth', 'moldy odor', 'slow drying wet towels in the bathroom' and 'water leakage', appeared simultaneously.

Dose measurement on both patients and operators during neurointerventional procedures using photoluminescence glass dosimeters.

BACKGROUND AND PURPOSE: Although radiation skin injuries associated with interventional radiology have been known as a critical issue, there are few reports mentioning direct measurement of the entrance skin dose (ESD). Thus, the purpose of this study was to clarify the regional distributions of ESDs in neurointervention. MATERIALS AND METHODS: Using photoluminescence glass dosimeters (PLDs), we measured the ESDs in 32 patients with a median age of 61.5 years. Angiographic parameters, including exposure time, dose-area product (DAP), and the number of digital subtraction angiography (DSA) studies and frames, were recorded. The ESDs of operators were analyzed by the same method. RESULTS: The maximum ESD of 28 therapeutic procedures was 1.8 +/- 1.3 Gy. Although the averaged ESD on the right temporo-occipital region was higher than that in other regions, disease-specific patterns were not observed. Statistically positive correlations were found between the maximum ESD and exposure time (r = 0.5283, P = .005), DAP (r = 0.7917, P < .001), the number of DSA studies (r = 0.5636, P = .002), and the number of DSA frames (r = 0.8583, P < .001). As for operators, ESDs to the left upper extremity were significantly higher than those to other regions. However, most of the ESDs were <0.2 mGy. Lead protective garments reduced the exposure doses to approximately one half to one tenth. CONCLUSION: It was shown that the regional ESD could be measured by applying the PLD. This method should contribute to reducing the dose accumulation in patients as well as in operators.

Elastic coefficient of a single polymer chain by using Brownian dynamics analysis.

The elastic coefficient of a single polystyrene chain has been experimentally evaluated by using Brownian dynamics analysis. The Brownian motion of the chain is probed using a particle trapped by optical tweezers with a negligibly small spring constant. The displacement of the particle due to Brownian motion is measured by an interferometer assembled using the same laser beam as the optical tweezers. Two methods are employed for Brownian dynamics analysis: (1) the analysis of the time course of the displacement of the particle and (2) the fitting of the power spectrum of Brownian motion with a Lorentzian. The elastic constant of a polystyrene chain in dichloromethane at 21 degrees C is estimated to be 6.4 x 10(-6) and 1.1 x 10(-5) N/m when methods (1) and (2) are employed, respectively. The elastic constant obtained by approximating the polystyrene chain to a freely jointed chain is in agreement with the experimentally evaluated elastic constant.

Efficacy of carotid artery stenting.

SUMMARY: Carotid Artery Stenting(CAS) was performed for 51 lesions in 46 patients for almost clinically symptomatic stenotic (> 70%)lesions of cervical carotid arteries. The lesions involved the contralateral occlusion cases in eight cases, the bilateral stenotic cases in six cases and the ipsilateral internal carotid artery stenotic cases in two cases. In all cases, endovascular technique was performed from a transfemoral approach under local anesthesia primarily. Under systemic heparinization, CAS was performed using a selfexpanding stent system. For the pre-stenting and post-stenting dilatation, percutaneous transluminal angioplasty (PTA) balloon catheters were used. The balloon was inflated up to the pressure of six to ten atoms for 20 to 30 seconds.After CAS, stenotic lesion dilated successfully in all cases (0-20% residual stenosis; mean, 5.5%) even if in the case of the contra-lateral occlusion cases, more than 90% severe stenotic cases, and the tortuous artery cases. The cerebral protection system was always used, mainly distal blocking balloon type. Only one symptomatic complication occurred after CAS. Follow-up ultrasonic carotid echogram was performed in 30 cases.No cases showed restenosis (more than 50% restenosis). Clinical follow up was performed in all cases for one to 41 months (mean, 15.2 months) and no clinical deterioration such as TIA or stroke occurred. CAS is technically feasible and can be performed with relatively low morbidity even if complicated stenotic cases. It may be useful, but the increase the number of patients and the long-term follow-up are necessary to evaluate the safety and usefulness of this method.

Percutaneous transluminal angioplasty for atherosclerotic stenoses of intracranial vessels.

SUMMARY: To study the efficacy and long-term outcome of percutaneous transluminal angioplasty (PTA) with/without stent placement for intracranial atherosclerotic stenoses, we reviewed our treated cases retrospectively. Between May 1992 and October 2003, PTA with/without stents was performed in 64 intracranial and skull base vessels in 62 patients, including 24 middle cerebral arteries, 16 internal carotid arteries, 13 vertebral arteries, and 11 basilar arteries. PTA was technically successful in 55 vessels (86%). However, four vessels (6%) failed to achieve satisfactory dilatation. We encountered five periprocedural strokes as symptomatic complications, for a mortality rate of 4.7% and a morbidity rate of 3.1%. All the patients with stent placements survived angioplasty without any complication. In the clinical follow-up available for one week to 11.5 years (mean, 4.7 years), there were three strokes related to the treated vessels. The annual stroke rate in the affected territory was estimated at 1.2% per year. According to these results, PTA for intracranial atherosclerotic stenoses seems to be a beneficial therapy for immediate anatomical results and long-term stroke prevention. Stent-assisted PTA could help patients achieve successful dilatation and avoid complications.

Angiographical change of guglielmi detachable coils. Treated cerebral aneurysm in acute stage.

SUMMARY: Acute angiographical changes for preventing acute rebleeding on GDC treated cerebral aneurysms were evaluated. From December 2000 to November 2002, 48 total aneurysms in 44 consecutive patients with acute SAH. Acute angiographical evaluations were carried out in 46 aneurysms, including 42 ruptured and 4 unruptured aneurysms. Two cases were excluded because of poor medical condition. In this series, there were no rebleeding cases in acute stage. In the initial embolization for the 46 aneurysms, CO was achieved in eight aneurysms, NR in 15 aneurysms and BF in 23 aneurysms. Acute angiographical observations showed progressive thrombosis in 17 aneurysms (37%). No changes were observed in remaining 29. No recanalization was observed in this series. Only one case of BF, inside the aneurysm bleb was still observed during follow up. Additional embolization was carried out. Progressive thrombosis was frequently observed in GDC treated cerebral aneurysms during acute stage. This angiographical finding seems to show prevention of rebleeding, which is considered important for the management of GDC treatment in acutely ruptured cerebral aneurysm.

Retreatment of cerebral aneurysms after guglielmi detachable coil embolization.

SUMMARY: Of 175 patients with 181 aneurysms initially treated with Guglielmi Detachable Coils (GDC), 25 were retreated. All retreatments except one were performed on previously ruptured aneurysms. Thirteen aneurysms were retreated because of recurrence, and 12 aneurysms were retreated to complete initial insufficient embolization. Sixteen patients underwent re-embolization and 9 patients were operated upon surgically. No complications related to the retreatment were experienced. We consider that repeat embolization should be attempted before considering surgical treatment in case that additional therapy is required. However, it is difficult to retreat aneurysms having wide necks. In regard to surgical clipping, aneurysms without a coil in the neck are easier to treat with primary clipping, whereas aneurysms with a coil mass in the neck are difficult to surgical clip. We have never used temporary clipping and coil extraction if the distance between the coil and the parent artery was wider than 2 mm. Emerging new embolic agents or devices and technical improvement might decrease the need for retreatment and increase long-term efficacy after endovascular treatment.

Mechanical properties of artificial tracheas composed of a mesh cylinder and a spiral stent.

Much work has been done on the materials used for mesh-type artificial tracheas, but a precise mechanical evaluation of these structures has not yet been performed. In the present study, we determined the mechanical properties of typical mesh-type artificial tracheas and compared them with those of native trachea. Four types of artificial trachea were made and used for the mechanical tests. The basic frame of all the specimens was composed of a mesh cylinder and a spiral stent. The specimen whose mesh was sealed with collagen sponge showed almost the same behavior in the force-strain curve under compression, suggesting that collagen sealing has little effect on mechanical properties. Agreement between measured and estimated mechanical properties was good, especially in the low strain region, suggesting that artificial tracheas can be designed in terms of mechanical properties by mainly considering the basic frame structure.

GABA-evoked chloride currents do not differ between dendrites and somata of rat neocortical neurons.

1. We performed patch-clamp recordings on acutely isolated somata and dendritic segments of rat neocortical neurons, in order to compare the reversal potential (E(GABA)) and relative density of GABA(A) receptor-mediated Cl(-) currents in these two cellular compartments. 2. Currents were recorded with the Cl(-)-impermeable pore former gramicidin (25--75 microg ml(-1)) in HCO(3)(-)-free bath solution. Voltage ramps (-110 to -30 mV) from a holding potential (V(h)) of -60 mV in the absence and presence of 2 microM GABA were used to construct instantaneous current-voltage relationships. Currents were abolished by co-application of GABA with the GABA(A) receptor antagonist bicuculline (40 microM). 3. GABA conductance, normalized to membrane surface area, was not different in somata and dendrites. In addition, E(GABA) was not different in the two compartments. 4. Replacement of intracellular K(+) with Cs(+) resulted in a significantly more depolarized E(GABA) in both somata and dendrites. These results suggest that the resting intracellular Cl(-) concentration ([Cl(-)](i)) is similar in somata and dendrites and that an outward Cl(-) transporter system maintains low [Cl(-)](i).

Increases in K+ conductance and Ca2+ influx under high glucose with suppressed Na+/K+-pump activity in rat myelinated nerve fibers.

To test the combined effect of high glucose and decreased Na+/K+-pump activity, a condition which closely mimics the diabetic state, on nerve ionic currents, changes in action potential and membrane current induced by high glucose in the presence of ouabain were investigated using voltage clamp analysis in rat single myelinated nerve fibers. In the presence of 0.1 mM ouabain, 30 mM glucose caused a progressive increase in the delayed K+ current as well as persistent decreases in action potential and Na+ current, suggesting that Na+/K+ pump plays an important role in preventing the increase in the K+ current. The latter increase was suppressed by a blocker of Ca2+-activated K+ channels. Two types of voltage-dependent Ca2+ channel blockers (L and N-type) as well as a Na+/Ca2+-exchange blocker diminished the ouabain-induced increase in K+ conductance. These results suggest that high glucose with suppressed Na+/K+ pump activity might induce an increase of Ca2+ influx through either Ca2+ channels or reverse Na+/Ca2+-exchange, possibly leading to the elevation of Ca2+-activated voltage-dependent K+ channels. Both a decrease in inward Na+ current and an increase in K+ conductance may result in decreased nerve conduction. In addition, a possible increase of axoplasmic Ca2+ concentration may lead to axonal degeneration. These results provide a clue for understanding the pathophysiologic mechanism of diabetic neuropathy.

The sera from GM1 ganglioside antibody positive patients with Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy blocks Na+ currents in rat single myelinated nerve fibers.

OBJECTIVE: To determine the possible role of anti-GM1 ganglioside antisera from patients with Gullain-Barr*e syndrome (GBS) or chronic inflammatory demyelinating polyneuropathy (CIDP) in the development of nerve dysfunction. METHODS: The effect of the anti-GM1 antibody positive antisera obtained from 4 GBS patients and 1 CIDP patient on membrane potential and ionic currents in rat single myelinated nerve fibers was investigated using the voltage clamp technique and compared with that of the anti-GM1 negative antisera obtained from 3 healthy controls and 2 GBS patients. RESULTS: In the presence of active complement, anti-GM1 positive antisera from 5 patients including 4 GBS patients and 1 CIDP patient significantly suppressed Na+ current more than anti-GM1 negative antisera. CONCLUSION: This study supports the notion that anti-GM1 antibody is one of the causative factors of conduction abnormality in GBS patients.

Variance analysis of current fluctuations of adenosine- and baclofen-activated GIRK channels in dissociated neocortical pyramidal cells.

Whole cell recordings were obtained from pyramidal cell somata acutely isolated from rat neocortex. In voltage-clamp mode, adenosine (0.3-1000 microM), and the GABA(B) receptor agonist, baclofen (1-300 microM), induced K+ current responses mediated by G protein-activated inwardly rectifying K+ (GIRK) channels. In our preparation, adenosine activated GIRK currents with an average EC(50) of 2 microM. Baclofen had an average EC50 of 26 microM. To estimate and compare unitary conductance and density of GIRK channels activated by either adenosine or baclofen, we performed variance analysis of current fluctuations associated with the application of the two agonists at increasing concentrations. Irrespective of the agonist tested, GIRK channels displayed an average single-channel conductance of 25 pS at our recording conditions ([K+]o: 60 mM). Assuming that GIRK channel conductance increases in proportion to the square root of [K+]o, this would translate into 5-6 pS at physiological ion gradients. GIRK channels activated by adenosine or baclofen were not only identical in terms of unitary conductance, they also displayed the same average density of 0.5 channels micron(-2) for both agonists. Our data strongly suggest that the two compounds recruit the same type of channel and thus most likely share a common transduction and effector system.

G protein-activated inwardly rectifying K+ (GIRK) currents in dendrites of rat neocortical pyramidal cells.

1. We performed patch-clamp recordings on acutely isolated dendritic segments and cell somata of rat neocortical pyramidal neurons to determine and compare the relative density of G protein-activated K+ (GIRK) currents in the two cellular compartments. 2. Hyperpolarizing voltage ramps and elevation of extracellular K+ concentration to 40 mM served to identify inwardly rectifying K+ currents. Near-saturating concentrations of adenosine (100 microM), baclofen (20 microM) and serotonin (20 microM) all produced robust GIRK currents in cell somata as well as in dendritic segments that were completely abolished by Ba2+ (200 microM). In addition to agonist-activated GIRK currents, both somata and dendrites displayed a constitutive Ba2+-sensitive inward rectification. 3. In order to compare the relative strengths of GIRK current responses in the two compartments, GIRK conductance was normalized to surface area. In contrast to intrinsic, G protein-independent inward rectification, which was comparable in size in the two compartments, all three agonists evoked significantly larger GIRK conductances in dendrites than in somata. 4. Our data suggest that several neurotransmitters might employ GIRK currents as a tool to directly modulate the electrical properties of dendrites. In concert with voltage-dependent K+ currents and the hyperpolarization-activated cation current (Ih) of the dendrite, GIRK currents should dampen dendritic excitability and thus influence various aspects of dendritic signal integration.

Confocal calcium imaging reveals an ionotropic P2 nucleotide receptor in the paranodal membrane of rat Schwann cells.

1. The paranodal Schwann cell region is of major importance for the function of a myelinated axon. In the present study we searched for a possible ionotropic effect of extracellular ATP in this Schwann cell compartment. 2. Whole-cell patch-clamp recordings from cultured rat Schwann cells revealed that ATP and 2'-3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP) induced a non-specific cation current. The effect of ATP was much enhanced in a Ca2+- and Mg2+-free solution. ADP, UTP and alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-meATP) had no effect. 3. Confocal Ca2+ imaging of myelinating Schwann cells in isolated rat spinal roots showed a BzATP-induced rise in the free intracellular Ca2+ concentration in the paranodal Schwann cell cytoplasm whereas alpha,beta-meATP and 2-(methylthio)-adenosine 5'-triphosphate were without effect. In contrast to the known metabotropic effect of UTP on these Schwann cell regions, the BzATP-induced Ca2+ signal was not transient, was unaffected by depletion of intracellular Ca2+ stores and dependent on the presence of extracellular Ca2+. 4. These results suggest that an ionotropic ATP receptor with electrophysiological and pharmacological characteristics of the P2X7 subtype of nucleotide receptors is functionally active in myelinating Schwann cells of peripheral nerves. Such a receptor might contribute to Schwann cell reactions in nerve injury or neuropathy.