Abstract This paper describes an experimental and numerical investigation of the dielectric resonators based on the MgTiO3 ceramic matrix, which relates to their dielectric properties in microwave. The resonators are compounds of the MgTiO3 added with 4, 6, 8, 10 and 12 wt% of the CaCu3Ti4O12. The manufacturing process of the resonators is based on the solid-state method. The properties of the permittivity and dielectric loss are elucidated using the Hakki and Coleman´s method. The experimental measurements of the dielectric resonators, acting as antennas, provide some results as return loss, gain, efficiency, bandwidth and input impedance. These results are coherent with the numerical investigation. The addition of the perovskite CaCu3Ti4O12 in the MgTiO3 ceramic matrix increased the value of the dielectric constant and it was obtained a higher value of 21.01 for the sample MgTiO3 added with 12% CaCu3Ti4O12. The temperature coefficient of resonant frequency (τf) was measured for all the samples and the best value obtained was 9.62 ppm/°C for the sample MgTiO3 added with 12% CaCu3Ti4O12. The material duly proposed, shows to be promising for applications as dielectric antennas and this study point out that it is possible to obtain a dielectric resonator antenna (DRA) with a temperature coefficient of resonant frequency close to zero.

Exercise intolerance due to impaired oxidative metabolism is a prominent symptom in patients with mitochondrial myopathy (MM), but it is still uncertain whether L-carnitine supplementation is beneficial for patients with MM. The aim of our study was to investigate the effects of L-carnitine on exercise performance in MM. Twelve MM subjects (mean age±SD=35.4±10.8 years) with chronic progressive external ophthalmoplegia (CPEO) were first compared to 10 healthy controls (mean age±SD=29±7.8 years) before they were randomly assigned to receive L-carnitine supplementation (3 g/daily) or placebo in a double-blind crossover design. Clinical status, body composition, respiratory function tests, peripheral muscle strength (isokinetic and isometric torque) and cardiopulmonary exercise tests (incremental to peak exercise and at 70% of maximal), constant work rate (CWR) exercise test, to the limit of tolerance [Tlim]) were assessed after 2 months of L-carnitine/placebo administration. Patients with MM presented with lower mean height, total body weight, fat-free mass, and peripheral muscle strength compared to controls in the pre-test evaluation. After L-carnitine supplementation, the patients with MM significantly improved their Tlim (14±1.9 vs 11±1.4 min) and oxygen consumption ( V ˙ O 2) at CWR exercise, both at isotime (1151±115 vs 1049±104 mL/min) and at Tlim (1223±114 vs 1060±108 mL/min). These results indicate that L-carnitine supplementation may improve aerobic capacity and exercise tolerance during high-intensity CWRs in MM patients with CPEO.

Os autores apresentam dois casos de polineuropatia carencial (PC) entre os índios Xavantes, em que o arroz era o alimento exclusivo no caso 1 e quase exclusivo no caso 2. O arroz consumido por esses índios era o beneficiado ou despolpado. A intoxicação pelo cianeto da mandioca ou de outros vegetais foi afastada. RELATO DOS CASOS. Foram observados em suas aldeias dois índios com 18 e 25 anos, com história progressiva de fraqueza, diminuição da força muscular e emagrecimento. Removidos ao Hospital São Paulo, notou-se, no exame neurológico do caso 1, atrofia da musculatura distal dos membros superiores e inferiores, déficit motor distalmente com grau zero na musculatura flexora, reflexos profundos abolidos, reflexo cutâneo plantar sem resposta bilateralmente, sensibilidade táctil, dolorosa e palestésica diminuída distalmente nos membros inferiores. No exame neurológico do caso 2, notou-se hiporreflexia proximal nos membros superiores, arreflexia nas porções distais dos membros superiores e inferiores, hipoestesia táctil e dolorosa nos pés, hipoacusia à direita. As eletroneuromiografias mostraram anormalidades compatíveis com polineuropatia sensitivo-motora simétrica, de padrão axonal desmielinizante no caso 1 e de predomínio desmielimizante no caso 2. Os exames de líquor foram normais. DISCUSSÃO. A polineuropatia foi caracterizada pela história clínica, pelos exames neurológicos, eletroneuromiográficos e líquor. O diagnóstico de PC ficou estabelecido pela história clínica e pelos exames eletroneuromiográficos sugestivos de polineuropatia periférica de causa nutricional. Esta PC não se enquadra nas mieloneuropatias como a neuropatia atáxica tropical, a paraparesia espástica e a neuropatia de Cuba. CONCLUSÃO. A PC dos Xavantes deve-se à deficiência da tiamina (vitamina B1), sendo o beribéri seco, tendo como causa o consumo do arroz beneficiado industrialmente como alimento exclusivo ou quase exclusivo. A polineuropatia dos Xavantes é diferente da neuropatia verificada entre os índios Kreen-Akrore e a observada entre os adolescentes índios do Parque do Xingu.

The authors present two cases of polyneuropathy deficiency among Xavante indians where the sole food was rice in case 1 and almost so in case 2. The rice consumed by these indians was processed or hulled. Intoxication by cyanide from maniot or other vegetables was excluded. CASE REPORT - Two indians aged 18 and 25 years with a progressive history of weaness, decrease in muscular force and thinning were observed in their villages. On removal to the Hospital São Paulo, atrophy of the distal musculature of the upper and lower limbs, motor deficit distally with zero degree in the flexor musculature, abolished deep reflexes, plantar cutaneous reflex without response bilaterally, decreased tactile, painful and pallesthetic sensitivity distally in the lower limbs were noted on neurological examination of case 1. On neurological examination of case 2 proximal hyporeflexia in the upper limbs, areflexia in the distal portions of the upper and lower limbs, tactile and painful hypoesthesia in the feet, right hypoacousis were noted. Electromyography showed abnormalities compatible with symmetric sensorimotor polyneuropathy with an axonal demyelination pattern in case 1 and predominantly demyelinizing in case 2. Cerebrospinal fluid tests were normal. DISCUSSION - Polyneuropathy was characterized by the clinical history and by neurological, electromyographic and cerebrospinal fluid tests. The diagnosis of polyneuropathy deficiency was established by the clinical history and by electromyography suggesting peripheral polyneuropathy of nutritional origin. This neuropathy deficiency does not fit myeloneuropathies such as ataxic tropical neuropathy, spastic paraparesis and Cuba neuropathy. CONCLUSION - The Xavante polyneuropathy deficiency is caused by thiamine (vitamin B1) deficiency, that is dry beriberi, owing to consumption of industrially processed rice as sole or almost sole food. The Xavante polyneuropathy is different from the neuropathy observed among Kreen-Akrore indians and from that of adolescent indians in the Xingu Park.

Para investigar a possibilidade de comprometimento auto imune no nervo periférico de pacientes com esclerose lateral amiotrófica (ELA) 83 biópsias do nervo periférico de 79 pacientes (51 sexo masculino, 28 sexo feminino) com média de idade de 62 anos (variação de 19 a 82) foram congeladas e coradas para demonstração de HLA-DR usando anticorpo monoclonal. Quarenta amostras (48%) mostraram expressão nitidamente aumentada de HLA-DR na região endoneural. Usando proteína S-100 como marcador, demonstramos que HLA-DR se expressava principalmente nas células de Schwann. Não encontramos co-expressão com HLA-DR usando anticorpos antineurofilamento ou antimielina, mas detectamos co-expressão de HLA-DR e anti-receptor de fator de crescimento nervoso na maioria das células HLA-DR positivas. Células inflamatórias foram encontradas ocasionalmente, sendo detectadas em somente 11 casos, predominantemente ao redor de vasos sanguíneos epineurais. Biópsias de nervo sensitivo e motor feitas simultaneamente mostraram maior expressão de HLA-DR em nervos motores de 2 dos 4 pacientes. A significância desses achados ainda não é clara. A presença de células endoneurais expressando HLA-DR sugere que mecanismos auto imunes podem estar envolvidos na ELA tendo a célula de Schwann como um dos principais alvos.

To investigate the possibility of local antigen presentation within the peripheral nerve in amyotrophic lateral sclerosis (ALS), cryostat sections of 83 peripheral nerve biopsies were stained for the demonstration of HLA-DR using a monoclonal antibody. Forty samples showed increased expression of HLA-DR in endoneurium. The phenotypic characteristics of the HLA-DR positive cells are chiefly Schwann cells, using S-100 protein as a marker. We did not detect any co-expression between HLA-DR and NF (axons) and HLA-DR and myelin marker. We also detected co-expression between HLA-DR and NGFr in a majority of HLA-DR positive cells. Inflammatory cells were infrequent, being detected only in 11 cases, predominantly around epineurial blood vessels. Motor and sensory nerve biopsies performed simultaneously showed higher expression of HLA-DR in motor nerves in 2 out of 4 patients. The significance of these findings is not clear. The presence of endoneurial cells expressing HLA-DR suggests that an autoimmune mechanism may be involved in ALS having Schwann as the main target.

A síndrome clínica produzida pelo vírus da dengue, inclui febre, exantema, cefaléia e especialmente mialgia. Entretanto, as possiveis alterações morfológicas do músculo esquelético, eventualmente relacionadas com a mialgia, ainda não haviam sido estudadas em seres humanos com dengue. Nosso objetivo foi estudar o substrato, anatomopatológico da mialgia nesses pacientes. Foram avaliados 15 pacientes com diagnóstico de dengue, forma clássica, com idades variando de 14 a 47 anos (mediana de 23 anos), sendo 4 do sexo masculino e 11 do sexo feminino, através de exame clínico e neurológico, exames laboratoriais e biópsia muscular com histoquímica, durante a epidemia de dengue em Alagoas, em 1987. Todos os pacientes apresentavam história de cefaléia, febre e mialgia intensa, sem fraqueza muscular. Ao exame clínico observou-se exantema em 4 pacientes, febre em 3 e discreta hepatomegalia em 3. O exame neurológico foi normal em todos e a enzima CK sérica estava pouco elevada em 3 pacientes. A biópsia muscular revelou discreto infiltrado inflamatório mononuclear perivascular em 12 pacientes, acúmulo lipídico em 11, predominância de fibras do tipo I em 6, raros focos de necrose em 3, proliferação mitocondrial em 3, centralização nuclear em 3 e "type grouping" em 2. As alterações mais frequentemente observadas na biópsia muscular, infiltrado inflamatório perivascular e acúmulo lipídico, podem estar relacionadas com a mialgia.

Dengue is known to produce a syndrome involving muscles, tendons and joints. The hallmark of this syndrome is severe myalgia but includes fever, cutaneous rash, and headache. The neuromuscular aspects of this infection are outlined only in isolated reports, and the muscle histopathological features during myalgia have not been described. In order to ascertain the actual neuromuscular involvement in dengue and better comprehend the histological nature of myalgia, we performed a clinical and neurological evaluation, a serum CPK level and a muscle biopsy (with histochemistry) in 15 patients (4 males), median age 23 years (range 14-47) with classic dengue fever, serologically confirmed, during the bra-zilian dengue epidemics from September 1986 to March 1987. All patients had a history of fever, headache and severe myalgia. Upon examination 4 had a cutaneous rash, 3 had fever, and 3 a small hepatomegaly. The neurological examination was unremarkable in all and included a manual muscle test. CPK was mildly elevated in only 3 patients. Muscle biopsy revealed a light to moderate perivascular mononuclear infiltrate in 12 patients and lipid accumulation in 11. Mild mitochondrial proliferation was seen in 3, few central nuclei in 3, rare foci of myonecrosis in 3, and 2 patients had type grouping. Dengue in our patients, produced myalgia but no detectable muscle weakness or other neuromuscular involvement. The main histopathological correlation with myalgia seems to be a perivascular mononuclear infiltrate and lipid accumulation.