We studied central nervous system lesions in patients with neuro-Behcet's disease using magnetic resonance imaging (MRI) of the brain and recording of brain-stem auditory evoked potentials (BAEPs). MRI revealed abnormal findings in seven of eight patients. MRI studies demonstrated extensive regions with high intensity signal in the brain stem and/or basal ganglia on T2-weighted images obtained during the acute stage of the disease in three patients. One of these patients had a strongly gadolinum-enhanced round lesion in the lower pons. In four of the other five patients with chronic disease, brain-stem atrophy was observed on T1-weighted images. Atrophic changes were more severe in the brain stem than in the cerebellum. Abnormal BAEPs were observed in three patients and consisted of prolongation of interpeak latency of waves III-V and defects of wave III or V. Abnormal BAEPs were recorded in patients with severe inflammatory changes or progression of atrophic changes in the brain stem. Our findings show that MRI and BAEPs are useful in detecting the presence and assessing the degree of neurological involvement in patients with neuro-Behçet's disease.

Bythe use of the experimental data of manyprevious studies, a newcorrelation for the pressure drop of a packed column was obtained in this work. The total pressure drop is expressed as the sum of the dry pressure drop and the wet pressure drop. The dry pressure drop originates mainly from the friction of gas rising through the void of the packed bed, and is expressed by the Fanning equation. The wet pressure drop originates from the increase in net gas velocity because of the smaller void of the packed bed owing to the liquid holdup, and therefore it is expressed as a function of liquid holdup, gas velocity, etc. The liquid holdup consists of static and dynamic holdups, and is correlated separately. Intr o du cti onIn previous studies, the method of dimensional analysis has been frequently used to correlate experimental values of the pressure drop of a packed column.Moreover, correlations of the pressure drop for dry packing (dry pressure drop) and for irrigated packing (total pressure drop) have been carried out separately, and no report expressing the total pressure drop consisting of the drop for dry packing and the residuals has apparently been published to date.Because of the smaller void of the packed bed in an operation with irrigation, the net gas velocity through the void becomes larger than that for dry packing. It is inferred that the difference between the total and dry pressure drops (wet pressure drop) is influenced strongly by the liquid holdup in the packed bed, because of the increase in the net gas velocity.However, there is a lack of studies referring to the relation of wet pressure drop and liquid holdup. In this paper, the experimental values of the many previous studies of the total pressure drop of a packed columnare correlated as the sumof the dry pressure drop and the wet pressure drop which is a function of liquid holdup, etc.

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