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排序方式: 共有893条查询结果,搜索用时 31 毫秒
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Heidi E Kirsch Mary Mantle Srikantan S Nagarajan 《Journal of clinical neurophysiology》2007,24(3):215-231
Both electroencephalography (EEG) and magnetoencephalography (MEG) localize epileptiform activity but may yield different results. This discordance may arise from different detection capabilities or from different data collection and interpretation techniques. Comparisons of MEG and EEG have focused on detection of individual spikes. However, side-by-side comparisons of results as used in the clinical setting is lacking. In this report, we present our empirical comparison. We reviewed 58 simultaneous MEG-EEG recordings (35 paired-sensors, 23 whole-head) from a diverse epilepsy population, comparing previous clinical MEG interpretations with new blinded EEG interpretations, noting lobar concordance of readers' judgments of regional abnormalities. A second-pass unblinded analysis, using all available clinical data, assessed the relative contribution and plausibility of the results of each technique. Concordance was high (85%) overall. Discordance was sometimes caused by constraints imposed by MEG dipole fitting techniques. Even when results of the techniques did not match, MEG often disambiguated the clinical scenario, especially when combined with imaging information. Thoughtful analysis of combined MEG-EEG datasets, beyond algorithm-based interictal spike detection, can help guide clinical decision-making even when concordance between techniques is imperfect. In some cases, EEG and MEG are synergistic and provide complementary information. 相似文献
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Srikantan S. Nagarajan Dominique M. Durand Kai Hsuing-Hsu 《Annals of biomedical engineering》1997,25(1):112-125
We determined the location of excitation for different positions of a round and butterfly coil duringin vitro magnetic stimulation of cut peripheral nerves. We analyzed the conditions under which excitation occurs, either at the termination
or at the peak of the field gradients (first spatial derivative of the electric field). These results were then compared to
predictions about the location of excitation sites from a theoretical model of magnetic stimulation of finite neuronal structures.
Excitation along a straight nerve occurred at terminations when 1) a coil was positioned close to the end of a nerve (at least
one diameter length from the end), 2) a nerve ended in a finite terminating impedance much greater than the axial resistance
of the nerve, 3) the induced electric field was of sufficient magnitude, pointing in a direction away from the axis of a nerve.
Excitation occurred at the negative peak of the field gradients along a nerve when 1) a coil was positioned far away from
the ends of a nerve, 2) there were no geometric or volume conductor inhomogeneities around a nerve, and 3) it was of sufficient
magnitude. Threshold strengths for excitation at terminations were significantly lower than that for field gradient excitation
and comparable to that due to geometric and volume conductor inhomogeneities. 相似文献
5.
Hepatic capillariasis 总被引:6,自引:0,他引:6
E B Attah S Nagarajan E N Obineche S C Gera 《American journal of clinical pathology》1983,79(1):127-130
The clinico-pathologic features of Capillaria hepatica infection in a 27-year-old Nigerian woman are discussed. This animal parasite has been encountered only rarely in humans. Less than 30 cases of human infection, mostly in children, having been recorded as far as the present authors are aware. This is the first case of hepatic capillariasis reported in West Africa. The pathologic features of this patient is marked by severe hepatic fibrosis, and this is correlated with disordered liver function. The possibility of histopathologic confusion with schistosomiasis mansoni is discussed. 相似文献
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Inhalation of regular insulin for meal time glucose control has been found to be safe, efficacious and reliable in Type I and Type II diabetics. The administration of regular insulin through the human lungs by inhalation has been conducted in at least 14 short studies in both normal and diabetic subjects beginning as early as 1925. In all studies, significant insulin absorption and lowering of blood glucose was observed in the absence of penetration enhancers. Although a concern of variable dosing was raised in early studies, the development of new reproducible delivery systems has ensured that the variability of aerosol insulin can be as good, if not better, than subcutaneous (SC) injection. In the longest controlled studies in humans to date, both Type I and Type II insulin-dependent diabetics used a novel inhaled dry powder insulin delivery system for 3 months for meal time glucose control. The study results indicate that inhaled insulin provides equivalent glucose control, measured by hemoglobin A1c, when directly compared to SC injection. Interim results from an additional study with Type II diabetics who were failing oral hypoglycemic agents suggest that adjunctive therapy with inhaled insulin markedly improved glycemic control with a low risk of hypoglycemia. In all the 3 month studies the system was efficacious, well tolerated, well liked, and resulted in reproducible results. A potential advantage of aerosol insulin is that it is more rapidly absorbed (serum peak at 5-60 min) and cleared than SC injection (peak at 60-150 min), which provides a more relevant and convenient therapy for meal time glucose control. The relative efficiency of insulin delivery by aerosol, compared to SC injection, has been estimated from the dose measured at the exit point of the aerosol device, and found to range between 8 and 25% of SC, depending on the study. 相似文献
7.
S.A. Syam Kumar Prabakar Sukumar Padmanaban Sriram Dhanabalan Rajasekaran Srinu Aketi Nagarajan Vivekanandan 《Medical Dosimetry》2012,37(4):436-441
The recalculation of 1 fraction from a patient treatment plan on a phantom and subsequent measurements have become the norms for measurement-based verification, which combines the quality assurance recommendations that deal with the treatment planning system and the beam delivery system. This type of evaluation has prompted attention to measurement equipment and techniques. Ionization chambers are considered the gold standard because of their precision, availability, and relative ease of use. This study evaluates and compares 5 different ionization chambers: phantom combinations for verification in routine patient-specific quality assurance of RapidArc treatments. Fifteen different RapidArc plans conforming to the clinical standards were selected for the study. Verification plans were then created for each treatment plan with different chamber-phantom combinations scanned by computed tomography. This includes Medtec intensity modulated radiation therapy (IMRT) phantom with micro-ionization chamber (0.007 cm3) and pinpoint chamber (0.015 cm3), PTW-Octavius phantom with semiflex chamber (0.125 cm3) and 2D array (0.125 cm3), and indigenously made Circular wax phantom with 0.6 cm3 chamber. The measured isocenter absolute dose was compared with the treatment planning system (TPS) plan. The micro-ionization chamber shows more deviations when compared with semiflex and 0.6 cm3 with a maximum variation of ?4.76%, ?1.49%, and 2.23% for micro-ionization, semiflex, and farmer chambers, respectively. The positive variations indicate that the chamber with larger volume overestimates. Farmer chamber shows higher deviation when compared with 0.125 cm3. In general the deviation was found to be <1% with the semiflex and farmer chambers. A maximum variation of 2% was observed for the 0.007 cm3 ionization chamber, except in a few cases. Pinpoint chamber underestimates the calculated isocenter dose by a maximum of 4.8%. Absolute dose measurements using the semiflex ionization chamber with intermediate volume (0.125 cm3) shows good agreement with the TPS calculated among the detectors used in this study. Positioning is very important when using smaller volume chambers because they are more sensitive to geometrical errors within the treatment fields. It is also suggested to average the dose over the sensitive volume for larger-volume chambers. The ionization chamber-phantom combinations used in this study can be used interchangeably for routine RapidArc patient-specific quality assurance with a satisfactory accuracy for clinical practice. 相似文献
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Cutaneous histoplasmosis with prominent parasitization of epidermal keratinocytes: report of a case
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Hedieh H. Honarpisheh Jonathan L. Curry Kristen Richards Priyadharsini Nagarajan Phyu P. Aung Carlos A. Torres‐Cabala Doina Ivan Carol R. Drucker Richard Cartun Victor G. Prieto Michael T. Tetzlaff 《Journal of cutaneous pathology》2016,43(12):1155-1160
Disseminated histoplasmosis most commonly occurs in immunosuppressed individuals and involves the skin in approximately 6% of patients. Cutaneous histoplasmosis with an intraepithelial‐predominant distribution has not been described. A 47‐year‐old man was admitted to our institution with fever and vancomycin‐resistant enterococcal bacteremia. He had been diagnosed with T‐cell prolymphocytic leukemia 4 years earlier and had undergone matched‐unrelated‐donor stem cell transplant 2 years earlier; on admission, he had relapsed disease. His medical history was significant for disseminated histoplasmosis 6 months before admission, controlled with multiple antifungal regimens. During this final hospitalization, the patient developed multiple 2–5 mm erythematous papules, a hemorrhagic crust across the chest, shoulders, forearms, dorsal aspect of the fingers, abdomen and thighs. Skin biopsy revealed clusters of oval yeast forms mostly confined to the cytoplasm of keratinocytes and within the stratum corneum; scattered organisms were present in the underlying superficial dermis without any significant associated inflammatory infiltrate. Special stains and immunohistochemical studies confirmed these to be Histoplasma organisms. We highlight this previously unrecognized pattern of cutaneous histoplasmosis to ensure its prompt recognition and appropriate antifungal therapy. 相似文献