RESUMO
Anomalous dispersion of X-ray diffraction at wavelengths near the X-ray K-absorption edge of sulfur at wavelengths around 5 A has been applied to single crystals of trypsin obtained from an ammonium sulfate solution. The multiwavelength anomalous-dispersion method based on 775 unique reflections (+183 Bijvoet mates) measured at three wavelengths near the K-absorption edge of sulfur in trypsin (two methionines and disulfide bridges of six cystines) reproduces the known features of the trypsin structure of a resolution of 4 A. It appears that there is anisotropic anomalous scattering from the disulfide bridges of cystine. The multiwavelength anomalous solvent contrast shows up at wavelengths near the K-absorption edge of the sulfate ions, which is shifted by 10 eV to higher energies with respect to that of sulfur in trypsin. The influence of the complex contrast of trypsin in 2.5 M ammonium sulfate on the dispersion of a low-order reflection is analyzed. The measurement of anomalous dispersion of X-ray diffraction at long wavelengths beyond 5 A requires a special diffractometer, the features of which are presented. An outstanding one is a detector system consisting of four multiwire proportional counters. Its efficiency is compared with that of imaging plates. The influence of radiation damage with soft X-ray diffraction from single crystals of trypsin is presented and possible remedies are discussed.
RESUMO
The spread of metastases to the brain and the leptomeninges is usually a terminal event in patients with known malignancies. We report on two patients, in whom the diagnosis of a diffusely metastasizing carcinoma was considerably delayed by the initial symptom of a peripheral facial nerve paralysis. The clinical, neuroradiologic and cerebrospinal fluid findings are discussed. A malignant neoplasm with diffuse or focal metastasis to the leptomeninges is a rare cause of peripheral facial paralysis of unclear genesis. The necessity of a lumbar puncture plus magnetic resonance imaging of the brain to enable an early diagnosis is emphasized.
Assuntos
Neoplasias Encefálicas/secundário , Paralisia Facial/etiologia , Neoplasias Primárias Desconhecidas/complicações , Adenocarcinoma Mucinoso/complicações , Adenocarcinoma Mucinoso/diagnóstico , Adenocarcinoma Mucinoso/secundário , Neoplasias Encefálicas/complicações , Neoplasias Encefálicas/diagnóstico , Humanos , Neoplasias Pulmonares/complicações , Neoplasias Pulmonares/diagnóstico , Imageamento por Ressonância Magnética , Masculino , Neoplasias Meníngeas/complicações , Neoplasias Meníngeas/diagnóstico , Neoplasias Meníngeas/secundário , Pessoa de Meia-Idade , Neoplasias Primárias Desconhecidas/diagnóstico , Neoplasias Gástricas/complicações , Neoplasias Gástricas/diagnóstico , Tomografia Computadorizada por Raios XRESUMO
Clomethiazol (Distraneurin) has decisively improved our therapeutic possibilities in delirium tremens. Furthermore, it has acquired a certain degree of importance in the treatment of agitation and sleep disorders in geronto-psychiatric patients. In the meantime, owing to the fact that doctors have been too ready to prescribe it for indications other than those mentioned above, a level of abuse of this substance--which has the potential for both psychological and physical dependence--has reached a point at which its usefulness threatens to become eclipsed.