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INTRODUCTION: Giant cell arteritis (GCA) is characterized by headaches, but few studies have examined the detailed characteristics of pathologically confirmed cases. We investigated the characteristics of GCA patients, particularly headache, and their correlation with pathological findings. METHODS: We retrospectively analyzed 26 patients (median age: 77.5 years, male: 38.4%) with GCA who underwent superficial temporal artery (STA) biopsy at the Japanese Red Cross Shizuoka Hospital between May 2001 and February 2022. All patients fulfilled the American College of Rheumatology and European League Against Rheumatism classification criteria for GCA. We focused on the relationship between clinical features, especially headache, and pathological findings. RESULTS: Twenty-four patients had unilateral, nonpulsatile, intermittent headaches. Transmural inflammation (TMI), a characteristic pathology of GCA, was present in 14 patients. Bivariate analysis revealed significant associations between the TMI and STA-related tenderness (odds ratio [OR]=11, 95% confidence interval [CI]=1.14 to 106.43, p=0.046) and the TMI and STA-related chordal thickening (OR=0.19, 95% CI=0.068 to 0.52, p=0.021). CONCLUSIONS: Headache in GCA patients was often unilateral, nonpulsatile, and intermittent. This study highlights the significant association of TMI with STA tenderness and ligamentous thickening, which has not been reported previously. Abnormal STA findings were significantly associated with pathological changes in GCA patients, emphasizing the importance of these lesions in predicting GCA.
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The progression of neuroinflammation after anti-parkinsonian therapy on the Parkinson's disease (PD) brain and in vivo evidence of the therapy purporting neuroprotection remain unclear. To elucidate this, we examined changes in microglial activation, nigrostriatal degeneration, and clinical symptoms longitudinally after dopamine replacement therapy in early, optimally-controlled PD patients with and without zonisamide treatment using positron emission tomography (PET). We enrolled sixteen PD patients (Hoehn and Yahr stage 1-2), and age-matched normal subjects. PD patients were randomly divided into two groups: one (zonisamide+) that did and one (zonisamide-) that did not undergo zonisamide therapy. Annual changes in neuroinflammation ([11C]DPA713 PET), dopamine transporter availability ([11C]CFT PET) and clinical severity were examined. Voxelwise differentiations in the binding of [11C]DPA713 (BPND) and [11C]CFT (SUVR) were compared with normal data and between the zonisamide+ and zonisamide- PD groups. The cerebral [11C]DPA713 BPND increased with time predominantly over the parieto-occipital region in PD patients. Comparison of the zonisamide+ group with the zonisamide- group showed lower levels in the cerebral [11C]DPA713 BPND in the zonisamide+ group. While the striatal [11C]CFT SUVR decreased longitudinally, the [11C]CFT SUVR in the nucleus accumbens showed a higher binding in the zonisamide+ group. A significant annual increase in attention score were found in the zonisamide+ group. The current results indicate neuroinflammation proceeds to the whole brain even after anti-parkinsonian therapy, but zonisamide coadministration might have the potential to ameliorate proinflammatory responses, exerting a neuroprotective effect in more damaged nigrostriatal regions with enhanced attention in PD.
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Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , Zonisamida , Enfermedades Neuroinflamatorias , Tomografía de Emisión de Positrones , Encéfalo/metabolismo , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismoRESUMEN
We investigate the phase-transition behavior of ionic liquid crystals, namely 1-methyl-3-alkylimidazolium tetrafluoroborate, [Cnmim]BF4, confined in cylindrical nanopores using differential scanning calorimetry, x-ray scattering, and dielectric relaxation spectroscopy. Here, n is the number of carbon atoms in the alkyl part of this ionic liquid crystal. For n = 10 and 12, the isotropic liquid phase changes to the smectic phase and then to a metastable phase for the cooling process. During the subsequent heating process, the metastable phase changes to the isotropic phase via crystalline phases. The transition temperatures for this ionic liquid crystal confined in nanopores decrease linearly with the increase in the inverse pore diameter, except for the transitions between the smectic and isotropic phases. In the metastable phase, the relaxation rate of the α-process shows the Vogel-Fulcher-Tammann type of temperature dependence for some temperature ranges. The glass transition temperature evaluated from the dynamics of the α-process decreases with the decrease in the pore diameter and increases with the increase in the carbon number n. The effect of confinement on the chain dynamics can clearly be observed for this ionic liquid crystal. For n = 10, the melting temperature of the crystalline phase is slightly higher than that of the smectic phase for the bulk, while, in the nanopores, the melting temperature of the smectic phase is higher than that of the crystalline phase. This suggests that the smectic phase can be thermodynamically stable, thanks to the confinement effect.
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The isothermal crystallization from the melt state of syndiotactic polypropylene (sPP) has been studied by wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and optical microscopy. The WAXD and SAXS results show the crystallization mechanism near the glass transition temperature in which the crystalline and mesomorphic nodules cover the entire sample with the formation of aggregation regions. For the SAXS analysis, the scattering function for the three-component system has been suggested. Furthermore, to analyze the growth kinetics of the aggregation region for sPP, the time-dependent structure factor combined with the homogeneous and inhomogeneous nucleation-and-growth kinetics has been suggested. The analysis shows that the growth kinetics of the aggregation region for sPP is the homogeneous nucleation-and-growth. The growth velocity of the aggregation region is a natural extrapolation of that of spherulite to the high supercooling region. These results might indicate that the crystallization with the nodular aggregation is a fundamental crystallization process near the glass transition temperature for polymers.
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The isothermal crystallization near the glass transition temperature from the melt state of poly(trimethylene terephthalate) has been studied by wide-angle x-ray diffraction (WAXD), small-angle x-ray scattering (SAXS), and optical microscopy. The SAXS and WAXD results show the crystallization mechanism in which the crystalline nodules cover the entire sample with the formation of aggregation regions. The analysis of the SAXS results using Kolmogorov-Johnson-Mehl-Avrami theory indicates that the formation kinetics of the aggregation regions is of three-dimensional homogeneous nucleation type. The analysis of the SAXS profiles using Sekimoto's theory provides the growth velocity and the nucleation rate of the aggregation region. The temperature dependence of the growth velocity of the aggregation region is a natural extrapolation of that of spherulite to the high supercooling region. The temperature dependence of the nucleation rate of the aggregation region is also represented by the parameters of the spherulitic growth rate. The result of the growth velocities of the aggregation region and the spherulite suggests the existence of precursors at the front of the crystal growth.
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OBJECTIVES: Decreased workforce productivity has a significant economic impact on healthcare systems. Presenteeism, the practice of working at reduced potential, is more harmful than absenteeism. Present workers most often experience musculoskeletal pain that is not mitigated by general exercise or stretching. We aimed to assess whether a regimen of pain neuroscience education (PNE) and exercise tailored to individual healthcare workers could reduce presenteeism and improve productivity. METHODS: An independent investigator randomized 104 medical professionals into two groups (intervention and control). The control group received general feedback after answering a questionnaire, while the intervention group received a 6-month plan of exercises and PNE created by a physical therapist with 10 years of experience. Our primary outcome was the scores of the Japanese version of the World Health Organization Health and Work Performance Questionnaire (WHO-HPQ) to investigate presenteeism; and our secondary outcomes were pain intensity, widespread pain index (WPI), and EuroQol 5-dimension (EQ5D-5L). RESULTS: In the intervention group, post intervention, we observed significant improvement in presenteeism, pain intensity, WPI, physical and psychological stress, and EQ5D-5L (P < .05). In the control group, we noted significant improvement only in the physical and psychological stress post intervention (P < .05). The results showed significant between-group differences in presenteeism post-intervention (P < .05). CONCLUSION: We demonstrated that a combination of PNE and exercise decreases presenteeism of healthcare workers. Our findings will help healthcare facilities carry out better employee management and ensure optimal productivity.
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Ejercicio Físico , Personal de Salud/psicología , Dolor Musculoesquelético/prevención & control , Educación del Paciente como Asunto/métodos , Presentismo , Adulto , Anciano , Femenino , Promoción de la Salud/métodos , Humanos , Japón , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Rendimiento Laboral , Lugar de TrabajoRESUMEN
AIM: The target Geriatric Nutritional Risk Index (GNRI) for patients on chronic maintenance hemodialysis is unclear. We aimed to determine the relationship between the GNRI and independent walking ability in such patients. METHODS: In the present retrospective cohort study, 90 patients receiving chronic maintenance hemodialysis were included. Logistic regression analyses were carried out to evaluate the relationship between the GNRI and independent walking ability. Receiver operating characteristic curve analysis was carried out to determine the cut-off GNRI for predicting independent walking ability. RESULTS: Multivariate logistic regression analysis showed significant differences in age (odds ratio [OR] 0.8, 95% confidence interval [CI] 0.6-0.9), creatinine generation rate percentage (OR 1.1, 95% CI 1.0-1.2), GNRI (OR 1.4, 95% CI 1.1-1.8; P < 0.01) and urea removal rate (OR 0.3, 95% CI 0.1-0.9; P < 0.05). The cut-off GNRI for independent walking ability was 86.7 (area under the curve 0.80, sensitivity 92.1%, specificity 66.7%, positive hit ratio 86.6%, negative hit ratio 78.3%). The factors correlated with survival in the univariate analysis were the GNRI, equilibrated Kt/V, urea removal rate, clear space rate, salt intake amount (P < 0.01), number of days of hospitalization and %creatinine generation rate (P < 0.05). The Cox proportional hazard regression model showed an OR of 0.77 (95% CI 0.32-1.8) at a GNRI <86/GNRI ≥86. In the multivariate survival analysis, we observed no significant differences in any of the factors. CONCLUSIONS: GNRI was correlated with walking ability, which indicated that GNRI might predict future walking ability; also, a GNRI of 87 might be the target for maintaining walking ability. Geriatr Gerontol Int 2018; 18: 1556-1561.
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Evaluación Nutricional , Diálisis Renal , Insuficiencia Renal/fisiopatología , Caminata/fisiología , Anciano , Femenino , Evaluación Geriátrica , Humanos , Pruebas de Función Renal , Modelos Logísticos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Curva ROC , Insuficiencia Renal/complicaciones , Insuficiencia Renal/terapia , Estudios Retrospectivos , Factores de RiesgoRESUMEN
BACKGROUND: Venous thromboembolism (VTE) has a long-term risk of recurrence, which can be prevented by anticoagulation therapy.MethodsâandâResults:The COMMAND VTE Registry is a multicenter registry enrolling 3,027 consecutive patients with acute symptomatic VTE between January 2010 and August 2014. The entire cohort was divided into the transient risk (n=855, 28%), unprovoked (n=1,477, 49%), and cancer groups (n=695, 23%). The rate of anticoagulation discontinuation was highest in the cancer group (transient risk: 37.3% vs. unprovoked: 21.4% vs. cancer: 43.5% at 1 year, P<0.001). The cumulative 5-year incidences of recurrent VTE, major bleeding and all-cause death were highest in the cancer group (recurrent VTE: 7.9% vs. 9.3% vs. 17.7%, P<0.001; major bleeding: 9.0% vs. 9.4% vs. 26.6%, P<0.001; and all-cause death: 17.4% vs. 15.3% vs. 73.1%, P<0.001). After discontinuation of anticoagulation therapy, the cumulative 3-year incidence of recurrent VTE was lowest in the transient risk group (transient risk: 6.1% vs. unprovoked: 15.3% vs. cancer: 13.2%, P=0.001). The cumulative 3-year incidence of recurrent VTE beyond 1 year was lower in patients on anticoagulation than in patients off anticoagulation at 1 year in the unprovoked group (on: 3.7% vs. off: 12.2%, P<0.001), but not in the transient risk and cancer groups (respectively, 1.6% vs. 2.5%, P=0.30; 5.6% vs. 8.6%, P=0.44). CONCLUSIONS: The duration of anticoagulation therapy varied widely in discordance with current guideline recommendations. Optimal duration of anticoagulation therapy should be defined according to the risk of recurrent VTE and bleeding as well as death.
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Anticoagulantes/administración & dosificación , Sistema de Registros , Terapia Trombolítica , Tromboembolia Venosa/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Anticoagulantes/efectos adversos , Femenino , Estudios de Seguimiento , Hemorragia/inducido químicamente , Hemorragia/enfermería , Hemorragia/terapia , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Neoplasias/tratamiento farmacológico , Neoplasias/mortalidad , Factores de Riesgo , Factores de Tiempo , Tromboembolia Venosa/mortalidadRESUMEN
Chain-level structure of semicrystalline polymers in melt- and solution-grown crystals has been debated over the past half century. Recently, 13Câ»13C double quantum (DQ) Nuclear Magnetic Resonance (NMR) spectroscopy has been successfully applied to investigate chain-folding (CF) structure and packing structure of 13C enriched polymers after solution and melt crystallization. We review recent NMR studies for (i) packing structure, (ii) chain trajectory, (iii) conformation of the folded chains, (iv) nucleation mechanisms, (v) deformation mechanism, and (vi) molecular dynamics of semicrystalline polymers.
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Poly(l-lactic acid) (L)/poly(d-lactic acid) (D) blends form a stereocomplex (SC) at a mixing ratio of 7/3-3/7. The stoichiometry and packing structure of L/D in the SC are controversial topics because the SC is semicrystalline and because the enantiomeric pair has the same chemical structure. In this study, both the stoichiometry and packing structure of 33% 13C CH3-labeled (l) L/nonlabeled D blends at mixing ratios of 7/3-3/7 were investigated by using solid-state (SS) NMR. The 13C CO signals in natural abundance provided the fractions of the SC (ΦSC), α, and amorphous regions of l-L/D blends. Moreover, the 33% 13CH3-labeled signals could determine the fraction of only l-L in the SC (ΦL) and amorphous region. These two data sets allowed us to determine the stoichiometry of l-L/D in the SC (ΦL-SC/ΦD-SC) to be 1/1. 13C-13C double-quantum (DQ) buildup curves of l-L in the SC followed one universal curve even at different mixing ratios. Comparison of the experimental and simulated DQ curves led to the conclusion that all SC crystals adopt a regular packing structure at varied mixing ratios.
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BACKGROUND: The neuroinflammatory glial response contributes to the degenerative process in Parkinson's disease (PD). However, the pattern of microglial progression remains unclear. METHODS: We evaluated microglial activation in early stage PD patients by quantifying changes in neuroinflammation using PET with [(11)C]DPA713, a selective PET tracer for microglial activation. Eleven PD patients (Hoehn and Yahr stages 1-2) without dementia underwent the [(11)C]DPA713 PET scan two times with 1 year apart. The binding potential (BPND) was estimated with the simplified reference tissue model. Voxelwise and regions of interest analyses were used to compare the regional BPND among groups. RESULTS: Significant increase in [(11)C]DPA713 BPND was found extrastriatally in the occipital, temporal and parietal cortex in PD patients, and the degree of BPND became much higher over the brain regions predominantly in the temporal and occipital cortex 1 year later. CONCLUSION: The current results indicated that an extrastriatal spreading of microglial activation reflects one of PD pathophysiology occurring at an early stage.
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Microglía/patología , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/patología , Tomografía de Emisión de Positrones , Acetamidas/metabolismo , Anciano , Radioisótopos de Carbono , Femenino , Humanos , Masculino , Microglía/metabolismo , Persona de Mediana Edad , Enfermedad de Parkinson/metabolismo , Pirazoles/metabolismo , Pirimidinas/metabolismoRESUMEN
The phase transition behavior and dynamics of ionic liquid crystals, 1-methyl-3-alkylimidazolium tetrafluoroborate with various alkyl chain lengths, were investigated by X-ray scattering, differential scanning calorimetry, optical microscopy, and dielectric relaxation spectroscopy to elucidate the mechanism of their structural and phase changes. A metastable phase was found to appear via a supercooled smectic phase on cooling. In the metastable phase, disorder in the smectic phase is partially frozen; thus, the phase has order higher than that of the smectic phase but lower than that of the crystalline phase. During the subsequent heating process, the frozen disorder activates, and a crystalline phase appears in the supercooled smectic phase before entering the smectic phase. The relationship between the phase behavior and the dynamics of charge carriers such as ions is also discussed.
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Benign hereditary chorea is a rare autosomal-dominant disorder that is characterized by childhood-onset nonprogressive chorea and normal cognitive function. Defects in NKX2-1 on chromosome 14q13, which encodes thyroid transcription factor 1, produce a concurrent clinical manifestation of chorea, respiratory distress, and hypothyroidism known as "brain-lung-thyroid syndrome." Here, the authors describe a video report of benign hereditary chorea in a Japanese female with a novel frameshift mutation of NKX2-1 (c.915_916insC) (p.Ala303ArgfsX132) that was initially misdiagnosed as ataxic cerebral palsy. In early infancy, especially before the appearance of chorea, benign hereditary chorea can be misdiagnosed as ataxic and dyskinetic cerebral palsy due to shared clinical features including motor delay, hypotonia, ataxic gait, and dystonia.
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The origin of two maxima in specific heat observed at the higher and the lower temperatures in the glass-transition region in the heating process has been studied for polymethyl methacrylate and polyvinyl chloride using differential scanning calorimetry, and the calculation was done using the phenomenological model equation under a thermal history of the typical annealing experiment composed of cooling, annealing, and heating. The higher maximum is observed above the glass-transition temperature, and it remains almost unchanged independent of annealing time t_{a}, while the lower one is observed above an annealing temperature T_{a} and shifts toward the higher one, increasing its magnitude with t_{a}. The analysis by the phenomenological model equation proposed in order to interpret the memory effect in the glassy state clarifies that under a typical annealing history, two maxima in specific heat essentially appear. The shift of the lower maximum toward higher temperatures from above T_{a} is caused by an increase in the amount of relaxation during annealing with t_{a}. The annealing temperature and the amount of relaxation during annealing play a major role in the determination of the number of maxima in the specific heat.
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Idiopathic hypoparathyroidism (IHP) is accompanied by cognitive impairment. We report the case of a 70-year-old IHP patient with cognitive disturbance. Brain computed tomography showed bilateral calcification in basal ganglia, thalamus, and cerebellum. Neuropsychological assessment revealed low scores for intelligence, memory, and perseverative errors. Brain positron emission tomography showed a significant reduction in [(18)F]-Fludeoxyglucose (FDG) uptake in bilateral frontal, left temporal and parietal cortices, along with a marked reduction in [(11)C]-flumazenil binding in left frontal, temporal, parietal, and bilateral cerebellum. These findings suggest cognitive impairment in IHP may be ascribed to GABAergic dysfunction, thus leading to, or coexisting with, cerebral hypometabolism.
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Encéfalo/metabolismo , Encéfalo/patología , Trastornos del Conocimiento/etiología , Cognición , Hipoparatiroidismo/metabolismo , Hipoparatiroidismo/patología , Receptores de GABA-B/metabolismo , Ácido gamma-Aminobutírico/metabolismo , Anciano , Ganglios Basales/patología , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Calcinosis/diagnóstico por imagen , Cerebelo/metabolismo , Cerebelo/patología , Corteza Cerebral/metabolismo , Trastornos del Conocimiento/metabolismo , Fluorodesoxiglucosa F18/administración & dosificación , Humanos , Hipoparatiroidismo/complicaciones , Hipoparatiroidismo/psicología , Masculino , Pruebas Neuropsicológicas , Tomografía de Emisión de Positrones/métodos , Radiofármacos/administración & dosificación , Tálamo/patología , Tomografía Computarizada por Rayos XRESUMEN
OBJECTIVE: To elucidate the genetic predisposition of Rasmussen syndrome (RS). METHODS: In 29 Japanese patients, we examined the genome sequences of cytotoxic T-lymphocyte-associated protein 4 (CTLA4), programmed cell-death 1 (PDCD1), and T-bet (TBX21) genes by direct sequencing, and evaluated the significance of SNPs (single nucleotide polymorphism) by comparison with Hap Map data. RESULTS: In all patients, no disease-causative mutations were found in CTLA4, PDCD1, and T-bet. However, rs231775 SNP in exon 1 of CTLA4 showed significant positive genotypic (p=0.0363) and allelic associations (p=0.0137) with onset of RS compared with Japanese controls, as did rs231779 SNP in intron 1 of CTLA4 (p=0.0467 and 0.0188, respectively). Also, rs2227982 SNP in exon 5 of PDCD1 showed significant positive genotypic and allelic associations with RS (p=0.0145 and 0.0114, respectively). Poor cognitive outcome (IQ below 50) was found in 0% of wild type (C/C), 9% of heterologous (C/T) and 25% of homologous (T/T) genotype of rs2227982. Quadriplegia was found only in homologous (T/T) genotype, and hemiplegia was in heterologous (C/T) and homologous (T/T) genotype of rs2227982. No association between SNPs of T-bet and RS onset was found. Regarding SNPs in promoter regions (rs4794067 and rs17250932) of T-bet, however, IQ below 50 was found in 19% of wild type (T/T) and 0% of heterologous (T/C) genotype of rs4794067, and in 19% of wild type (T/T) and 0% of heterologous (T/C) genotype of rs17250932. Quadriplegic patients were found only in wild-type patients (rs4794067 and rs17250932). CONCLUSIONS: We identified three SNPs (rs231775, rs231779, rs2227982) as some of the SNPs associated with onset of Japanese RS. We need further studies in other populations to confirm these genetic predispositions in RS.
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Pueblo Asiatico/genética , Antígeno CTLA-4/genética , Encefalitis/genética , Variación Genética , Receptor de Muerte Celular Programada 1/genética , Proteínas de Dominio T Box/genética , Adolescente , Antígeno CTLA-4/inmunología , Niño , Preescolar , Encefalitis/inmunología , Femenino , Predisposición Genética a la Enfermedad , Variación Genética/inmunología , Humanos , Masculino , Polimorfismo de Nucleótido Simple/genética , Polimorfismo de Nucleótido Simple/inmunología , Receptor de Muerte Celular Programada 1/inmunología , Estudios Retrospectivos , Proteínas de Dominio T Box/inmunologíaRESUMEN
Antibodies against glutamic acid decarboxylase (GAD-Abs) are associated with cerebellar ataxia, which is refractory to treatment with GABAergic drugs. To investigate the GABAergic neuronal system in vivo, we performed a combined positron emission tomography (PET) study with [(11)C]-flumazenil and [(18)F]-fluorodeoxyglucose (FDG) in three patients with cerebellar ataxia with GAD-Abs. The GABA-A receptor function was investigated using flumazenil, which is a selective GABA-A receptor ligand, while FDG-PET using a three-dimensional stereotactic surface projection analysis was performed to estimate the metabolic rates of glucose (MRGlc) in the patients. GABAergic drugs showed no efficacy for the cerebellar ataxia in all three patients, and all three displayed a significant decrease in flumazenil binding in the cerebellum. No MRGlc decrease in the cerebellum was found in the two patients who presented with amelioration of cerebellar ataxia following intravenous immunoglobulin (IVIG) therapy, whereas a significant MRGlc decrease in the cerebellar hemisphere was observed in another patient who showed severe cerebellar atrophy on magnetic resonance images and no response to the IVIG therapy. The decreased flumazenil binding in the present patients indicated cerebellar GABA-A receptor impairment, which may be due to either neuronal cell loss, as demonstrated by the decreased MRGlc, or a dysfunction in GABAergic neuronal inhibition. Although GAD-Abs have been postulated to prevent the synthesis of GABA, resulting in decreased GABAergic transmission, the GABA-A receptor impairment may play another pathogenic role in cerebellar ataxia associated with GAD-Abs resulting in a condition refractory to GABAergic drug therapy.
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Encéfalo/diagnóstico por imagen , Ataxia Cerebelosa/diagnóstico por imagen , Ataxia Cerebelosa/metabolismo , Glutamato Descarboxilasa/inmunología , Receptores de GABA-A/metabolismo , Adulto , Autoanticuerpos/sangre , Autoanticuerpos/inmunología , Autoantígenos/inmunología , Encéfalo/metabolismo , Encéfalo/patología , Ataxia Cerebelosa/inmunología , Femenino , Flumazenil , Fluorodesoxiglucosa F18 , Humanos , Masculino , Tomografía de Emisión de Positrones , RadiofármacosAsunto(s)
Encéfalo/diagnóstico por imagen , Receptores de GABA/metabolismo , Degeneraciones Espinocerebelosas/diagnóstico por imagen , Ácido gamma-Aminobutírico/metabolismo , Encéfalo/metabolismo , Femenino , Humanos , Persona de Mediana Edad , Tomografía de Emisión de Positrones , Degeneraciones Espinocerebelosas/metabolismoRESUMEN
The effects of thermal history on the enthalpy relaxation in polystyrene are studied by differential scanning calorimetry. The temperature dependence of the specific heat in the liquid and the glassy states, that of relaxation time, and the exponent of the Kohlrausch-Williams-Watts function are determined by measurements of the thermal response against sinusoidal temperature variation. A phenomenological model equation previously proposed to interpret the memory effect in the frozen state is applied to the enthalpy relaxation and the evolution of entropy under a given thermal history is calculated. The annealing below the glass transition temperature produces two effects on enthalpy relaxation: the decay of excess entropy with annealing time in the early stage of annealing and the increase in relaxation time due to physical aging in the later stage. The crossover of these effects is reflected in the variation of temperature of the maximum specific heat observed in the heating process after annealing and cooling.
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Our purpose in this study was to investigate the behavior of signal harmonics in magnetic particle imaging (MPI) by experimental and simulation studies. In the experimental studies, we made an apparatus for MPI in which both a drive magnetic field (DMF) and a selection magnetic field (SMF) were generated with a Maxwell coil pair. The MPI signals from magnetic nanoparticles (MNPs) were detected with a solenoid coil. The odd- and even-numbered harmonics were calculated by Fourier transformation with or without background subtraction. The particle size of the MNPs was measured by transmission electron microscopy (TEM), dynamic light-scattering, and X-ray diffraction methods. In the simulation studies, the magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively. The odd- and even-numbered harmonics were calculated by Fourier transformation under various conditions of DMF and SMF and for three different particle sizes. The behavior of the harmonics largely depended on the size of the MNPs. When we used the particle size obtained from the TEM image, the simulation results were most similar to the experimental results. The similarity between the experimental and simulation results for the even-numbered harmonics was better than that for the odd-numbered harmonics. This was considered to be due to the fact that the odd-numbered harmonics were more sensitive to background subtraction than were the even-numbered harmonics. This study will be useful for a better understanding, optimization, and development of MPI and for designing MNPs appropriate for MPI.