Analysis of the isomerization of diketopiperazine consisting of proline and aromatic amino acid residues using nuclear magnetic resonance.

Under different concentrations of the base potassium deuteroxide KOD, the progress of reactions, such as enolization, D-substitution, isomerization, and conformational changes of diketopiperazine cyclo(L-Pro-L-Xxx) and cyclo(D-Pro-L-Xxx) (Xxx = Phe, Tyr) in D2O solution, was investigated by 1H nuclear magnetic resonance (NMR). Cyclo(L-Pro-L-Xxx) is mostly isomerized to cyclo(D-Pro-L-Xxx) in D2O solution, whereas cyclo(D-Pro-L-Xxx) is only slightly isomerized to cyclo(L-Pro-L-Xxx) even under stronger basic conditions. After adding a deuterated organic solvent (CD3COCD3, CD3SOCD3 or CD3OD) to a D2O solution of cyclo(L-Pro-L-Xxx), cyclo(D-Pro-L-Xxx), or increasing the temperature of the D2O solution, CH-π interaction between H9 and the benzene ring of cyclo (D-Pro-L-Xxx) was stronger than that between H8α and the benzene ring of cyclo(L-Pro-L-Xxx).

[Acute disseminated encephalomyelitis following influenza vaccination: report of a case with callosal disconnection syndrome].

We present a case of callosal disconnection syndrome as a rare manifestation of acute disseminated encephalomyelitis (ADEM). A dextral 48-year-old Japanese woman received trivalent inactivated influenza vaccine in mid-November 2011. Twenty days later, she was found to be in a daze. Subsequently, she developed abnormal behavior and gait disturbance, and she was disoriented regarding time and place. Nystagmus and abnormal ocular movements were absent. Upper limb power was normal, whereas her lower limbs were mildly weak. Tendon reflexes were normally evoked without pathological reflexes. There was no sensory impairment. Serum CRP levels were slightly elevated; other routine laboratory tests, thyroid functions, and vitamin B1 levels were within the normal range. Cerebrospinal fluid examination revealed that it was acellular with a protein level of 54 mg/dl and high myelin basic protein level. Fluid-attenuated inversion recovery MR images revealed a large hyperintense lesion in the corpus callosum, but the lower part of the splenium was spared. Flow voids were observed in the pericallosal arteries. She was diagnosed with post-vaccination ADEM and vigorously treated with an intravenous infusion of methylprednisolone (1 g/day for 6 days) and immunoglobulin (1.2 g/kg). Gait disturbance and disorientation rapidly improved; however, tactile anomia, ideomotor apraxia, ideational apraxia, and agraphia of the left hand were present one month after onset. She had no aphasia or alexia.Interestingly, the patient's left unilateral agraphia was more prominent in kana than kanji (an article in Japanese text) for polysyllabic words, whereas she could write kana characters to dictation. Changes in the sequential order of kana characters within a word were observed. These findings were similar to those observed in pure agraphia associated with lesions in the posterior part of the left middle frontal gyrus. Thus, an interhemispheric mechanism is probably involved in the selection and arrangement of kana characters to form words.