Cortical thickness is related to working memory performance after non-invasive brain stimulation

Non-invasive brain stimulation (NIBS) probing the dorsolateral prefrontal cortex (DLPFC) has been shown to have little effect on working memory. The variability of NIBS responses might be explained by inter-subject brain anatomical variability. We investigated whether baseline cortical brain thickness of regions of interest was associated with working memory performance after NIBS by performing a secondary analysis of previously published research. Structural magnetic resonance imaging data were analyzed from healthy subjects who received transcranial direct current stimulation (tDCS), intermittent theta-burst stimulation (iTBS), and placebo. Twenty-two participants were randomly assigned to receive all the interventions in a random order. The working memory task was conducted after the end of each NIBS session. Regions of interest were the bilateral DLPFC, medial prefrontal cortex, and posterior cingulate cortex. Overall, 66 NIBS sessions were performed. Findings revealed a negative significant association between cortical thickness of the bilateral dorsolateral prefrontal cortex and reaction time for both tDCS (left: P=0.045, right: P=0.037) and iTBS (left: P=0.007, right: P=0.007) compared to placebo. A significant positive association was found for iTBS and posterior cingulate cortex (P=0.03). No association was found for accuracy. Our findings provide the first evidence that individual cortical thickness of healthy subjects might be associated with working memory performance following different NIBS interventions. Therefore, cortical thickness could explain - to some extent - the heterogeneous effects of NIBS probing the DLPFC.

Alternative chromatographic system for the quality control of lipophilic technetium-99m radiopharmaceuticals such as [99mTc(MIBI)6]+

Knowledge of the radiochemical purity of radiopharmaceuticals is mandatory and can be evaluated by several methods and techniques. Planar chromatography is the technique normally employed in nuclear medicine since it is simple, rapid and usually of low cost. There is no standard system for the chromatographic technique, but price, separation efficiency and short time for execution must be considered. We have studied an alternative system using common chromatographic stationary phase and alcohol or alcohol:chloroform mixtures as the mobile phase, using the lipophilic radiopharmaceutical [99mTc(MIBI)6]+ as a model. Whatman 1 modified phase paper and absolute ethanol, Whatman 1 paper and methanol:chloroform (25:75), Whatman 3MM paper and ethanol:chloroform (25:75), and the more expensive ITLC-SG and 1-propanol:chloroform (10:90) were suitable systems for the direct determination of radiochemical purity of [99mTc(MIBI)6]+ since impurities such as99mTc-reduced-hydrolyzed (RH),99mTcO4- and [99mTc(cysteine)2]-complex were completely separated from the radiopharmaceutical, which moved toward the front of chromatographic systems while impurities were retained at the origin. The time required for analysis was 4 to 15 min, which is appropriate for nuclear medicine routines.

Radioiodine plus recombinant human thyrotropin do not cause acute airway compression and are effective in reducing multinodular goiter

Recombinant human thyrotropin (rhTSH) reduces the activity of radioiodine required to treat multinodular goiter (MNG), but acute airway compression can be a life-threatening complication. In this prospective, randomized, double-blind, placebo-controlled study, we assessed the efficacy and safety (including airway compression) of different doses of rhTSH associated with a fixed activity of 131I for treating MNG. Euthyroid patients with MNG (69.3 ± 62.0 mL, 20 females, 2 males, 64 ± 7 years) received 0.1 mg (group I, N = 8) or 0.01 mg (group II, N = 6) rhTSH or placebo (group III, N = 8), 24 h before 1.11 GBq 131I. Radioactive iodine uptake was determined at baseline and 24 h after rhTSH and thyroid volume (TV, baseline and 6 and 12 months after treatment) and tracheal cross-sectional area (TCA, baseline and 2, 7, 180, and 360 days after rhTSH) were determined by magnetic resonance; antithyroid antibodies and thyroid hormones were determined at frequent intervals. After 6 months, TV decreased significantly in groups I (28.5 ± 17.6 percent) and II (21.6 ± 17.8 percent), but not in group III (2.7 ± 15.3 percent). After 12 months, TV decreased significantly in groups I (36.7 ± 18.1 percent) and II (37.4 ± 27.1 percent), but not in group III (19.0 ± 24.3 percent). No significant changes in TCA were observed. T3 and free T4 increased transiently during the first month. After 12 months, 7 patients were hypothyroid (N = 3 in group I and N = 2 in groups II and III). rhTSH plus a 1.11-GBq fixed 131I activity did not cause acute or chronic changes in TCA. After 6 and 12 months, TV reduction was more pronounced among patients treated with rhTSH plus 131I.

Effect of a selective nonsteroidal anti-inflammatory inhibitor of cyclooxygenase-2 on the small bowel of rats

The pathogenesis of nonsteroidal anti-inflammatory drug (NSAID) enteropathy is a complex process involving the uncoupling of mitochondrial oxidative phosphorylation and inhibition of cyclooxygenase (COX). Rofecoxib, a selective inhibitor of COX-2, has shown less gastric damage, but the same beneficial effect is not clear in the case of the small bowel. Fifty-seven male Wistar rats (250-350 g) were divided into three groups (N = 19 each) to evaluate the effect of this NSAID on the rat intestine. The groups received 2.5 mg/kg rofecoxib, 7.5 mg/kg indomethacin or water with 5 percent DMSO (control) given as a single dose by gavage 24 h before the beginning of the experiment. A macroscopic score was used to quantify intestinal lesions and intestinal permeability was measured using [51Cr]-ethylenediaminetetraacetic acid ([51Cr]-EDTA). The extent of intestinal lesion, indicated by a macroscopic score, was significantly lower when rofecoxib was administered compared to indomethacin (rofecoxib = 0.0 vs indomethacin = 63.6 ± 25.9; P < 0.05) and did not differ from control. The intestinal permeability to [51Cr]-EDTA was significantly increased after indomethacin (control = 1.82 ± 0.4 vs indomethacin = 9.12 ± 0.8 percent; P < 0.0001), but not after rofecoxib, whose effect did not differ significantly from control (control = 1.82 ± 0.4 vs rofecoxib = 2.17 ± 0.4 percent; ns), but was significantly different from indomethacin (indomethacin = 9.12 ± 0.8 vs rofecoxib = 2.17 ± 0.4 percent; P < 0.001). In conclusion, the present data show that rofecoxib is safer than indomethacin in rats because it does not induce macroscopic intestinal damage or increased intestinal permeability.

Avaliaçäo de atividade inflamatória na osteomielite crônica: contribuiçäo da cintilografia com anticorpos policlonais / Evaluation of inflammatory activity in chronic osteomyelitis: contribution of scintigraphy with polyclonal antibodies

OBJETIVO: O diagnóstico de osteomielite crônica em atividade ou sobreposta a outras patologias é difícil, pois estas situações mascaram os achados radiológicos de infecção. A especificidade da cintilografia do esqueleto ou com gálio-67 também é reduzida pela influência da remodelação óssea na captação destes radiofármacos. Anticorpos policlonais marcados com tecnécio-99m (Tc-99m-IgG) apresentam captação independente do metabolismo ósseo, sendo um dos radiofármacos em investigação para avaliação mais específica de infecção. CASUÍSTICA E MÉTODO: Neste estudo comparou-se a cintilografia com Tc-99m-IgG, cintilografia óssea trifásica e cintilografia com gálio-67 no diagnóstico da osteomielite crônica em atividade em 23 segmentos ósseos; correlacionando-as com dados clínico-laboratoriais e radiológicos. RESULTADOS: Oito dos 23 segmentos foram classificados como infectados, 11 não infectados e quatro inconclusivos. A sensibilidade e especificidade encontradas para cintilografia óssea, com gálio-67 e com Tc-99m-IgG foram, respectivamente, 88 e 36 por cento, 75 e 73 por cento, 88 e 82 por cento. CONCLUSÃO: Os resultados sugerem que a Tc-99m-IgG possa ser utilizada no diagnóstico da osteomielite crônica em atividade.

Experiental evaluation of brain spect using d, 1 - HMPAO 99m Tc in dogs. Anatomo-physiological implications

O d, 1-Hexametilpropileno oxima marcado com o tecnécio-99m (potência 99m Tc-HMPAO) é um importante radiofármaco usado tanto para imagens tomográficas cerebrais quanto na marcaçäo "in vitro" de leucócitos. A crescente utilizaçäo deste radiofármaco no estudo de doenças neurológicas no homem levou-nos à obtençäo de "kits" de HMPAO para ser marcado pelo tecnécio-99m. Neste trabalho apresentamos o estudo experimental efetuado com "kits" liofilizados de d, 1-HMPAO elevado à 99mTc desenvolvidos em nosos laboratórios, comparando inclusive com aqueles encontrados no comércio. As imagens cerebrais inicialmente foram feitas em coelhos, entretanto os melhores resultados foram obtidos em cäes. Assim, selecionaram-se seis cäes sem raça definida, considerados clinicamente normais para obtençäo das imagens cintilográficas do cérebro e o "washout" das regiöes de interesse (ROIs). Os estudos experimentais em animais e a considerável reduçäo do custo do radiofármaco mostrou-nos a possibilidade da utilizaçäo destes exames na clínica veterinária, especialmente de pequenos animais. Por outro lado, a perfusäo do d, 1-HMPAO elevado à 99mTc mostra que a concentraçäo do radiofármaco se faz ao mesmo tempo na regiäo do cérebro e nas fossas nasais, demonstrando a existência de estruturas iguais às da barreira hemo-encefálica nesta última regiäo

MRI and brain SPECT findings in patients with unilateral temporal lobe epilepsy and normal CT scan

Foram estudados 26 pacientes com epilepsia do lobo temporal clinicamente documentada por vários EEGs com atividade epileptiforme intercrítica e TC de crânio normal SPECT com TC HMPAO e ressonância magnética (RM) foram realizados em todos os casos 61,5 por cento (n=17) dos SPECTs revelaron algum tipo de anormalidade. Atrofia hipocampal, nas imagens enfatizadas em T1 e presença de hipersinal nas imagens enfatizadas em T2, sugerindo esclerose mesial temporal, foram o principal achado (n=12,75 por cento das RM anormais). RM correlacionou-se ao ECG em 50 por cento (n=13). Concordância entre RM e SPECT ocorreu em 30.7 por cento (n=8) e entre SPECT e EEG em 57.7 por cento (n=15), RM, SPECT e EEG foram congruentes em 26.9 por cento (n=7). Estes resultados refletem o valor do SPECT intercrítico e RM na detecçäo e lateralizaçäo de anormalidades em epilepsia do lobo temporal. Por outro lado, em dois casos, o SPECT correlacionou-se mal com o EEG. Este método funcional näo deve ser utilizado isoladamente na detecçäo de focos temporais. RM é mais útil do que a TC como recurso de neuroimagem na epilepsia do lobo temporal. Ela pode detectar pequenas lesöes estruturais e esclerose mesial temporal, näo facilmente identificáveis pela TC

Feocromocitoma intratorácico: relato de caso / Intrathoracic pheochromocytoma: a case report

Os autores apresentam um caso de feocromocitoma intratorácico demonstrado e localizado através da cintilografia com MIBG-131, e sua correlaçäo com a radiografia convencional e tomografia computadorizada