Separation of isomers using a differential mobility analyser (DMA): Comparison of experimental vs modelled ion mobility.

Mass spectrometry is uniquely suited to identify and quantify environmentally relevant molecules and molecular clusters. Mass spectrometry alone is, however, not able to distinguish between isomers. In this study, we demonstrate the use of both an experimental set-up using a differential mobility analyser, and computational ion mobility calculations for identification of isomers. In the experimental set-up, we combined electrospray ionisation with a differential mobility analyser time-of-flight mass spectrometer to separate environmentally relevant constitutional isomers, such as catechol, resorcinol and hydroquinone, and configurational isomers, such as cyclohexanediols and fatty acids (i.e., oleic and elaidic acids). Computational ion mobility predictions were obtained using the Ion Mobility Software (IMoS) program. We find that isomer separation can be achieved with the differential mobility analyser, while for catechol, resorcinol and hydroquinone, the computational predictions can reproduce the experimental order of the ion mobilities between the isomers, confirming the isomer identification. Our experimental set-up allows analysis both in the gas and liquid phase. The differential mobility analyser can, moreover, be combined with any mass spectrometry set-up, making it a versatile tool for the separation of isomers.

Benefits of surgical repair of coarctation of the aorta in patients older than 50 years.

BACKGROUND: Most patients with unrepaired coarctation of the aorta die before the age of 50 years. In patients who present at an older age, the indications for surgical treatment are controversial because the benefits of operating are unclear. METHODS: At follow-up investigation from 0.5 to 11.5 years (mean, 4 years) after primary surgical correction of coarctation in 15 patients aged 50 to 63 years (mean, 54 years), we analyzed the preoperative and postoperative complications, symptoms, need for antihypertensive drugs, and blood pressure at rest and during exercise. RESULTS: Preoperatively no patient had normal blood pressure at rest despite combined antihypertensive medication. There was no significant mortality or morbidity after repair. At follow-up examination only 3 patients had at rest mild hypertension, the other 12 patients were normotensive. Of the 11 tested patients, 8 displayed systolic arterial hypertension during exercise. CONCLUSIONS: Surgical correction of coarctation can be performed after the age of 50 years with low surgical risk. Operation reduces systolic hypertension at rest and permits more effective medical treatment. Despite persistence of the hypertension during exercise, symptomatic improvement occurs in most patients.

[Metastasizing malignant germ cell tumor of the testis with infiltration of the thoracic aorta--a case for metastasis surgery]. / Metastasierender maligner Keimzelltumor des Hodens mit Infiltration der Aorta thoracica--Kasuistik zur Metastasenchirurgie.

HISTORY AND FINDINGS: A 33-year-old man was admitted 7 years after a testicular teratomatous carcinoma had first been diagnosed, treated by a right orchiectomy and two-stage radical retroperitoneal lymphadenectomy. Five years later the first mediastinal metastases were treated with high-dosage chemotherapy and autologous germ-cell transplantation, and remaining paraaortic--mediastinal tumour tissue was resected. Two years later another tumour at that site was only partially resected. A curing treatment seemed impossible, because the aortic wall had been invaded. TREATMENT AND COURSE: Five months after re-thoracotomy the metastasis and the invaded aortic segment were resected, the latter replaced by a vascular prosthesis. Histology indicated metastasis of a malignant teratoma of intermediate type. There has been no evident recurrence in the last 20 months. CONCLUSION: Combined orchidectomy, lymphadenectomy, high-dosage chemotherapy with cisplatin and autologous germ-cell transplantation at present constitute the standard treatment of malignant testicular germ-cell tumour. In case of metastatic infiltration of vital structures, such as the aortic wall, special operative procedures can prolong the period of remission when the success of a standard treatment seems limited.