Chordoma: role of radiation therapy

The treatment of 21 patients with a diagnosis of chordoma seen over a 20-year period is described. The 13 men and eight women (ratio 1.6:1) ranged in age from 7 to 82 years (average, 50 years). Eleven chordomas arose from the clivus; the others originated in the sacral region (three patients), thoracic spine (one), cervical spine (three), and lumbar spine (three). Primary treatment consisted of surgery, reserving radiation therapy for recurrence in the majority of patients. Radiation doses, delivered with megavoltage equipment, ranged between 5,000 cGy delivered over 5 weeks and 6,600 cGy over 6 1/2 weeks. Irradiation produced significant tumor control, with remission of symptoms from 1 to 6 years. The combination of high-dose radiation therapy and complete or subtotal surgical resection offers the best chance for prolonged survival in this group of patients.     

Noninvasive differentiation of tumors with use of localized H-1 MR spectroscopy in vivo: initial experience in patients with cerebral tumors

A recently developed method for image-selected localized hydrogen-1 magnetic resonance (MR) spectroscopy was assessed in the differential diagnosis of nine primary and secondary cerebral tumors, including four gliomas, two meningiomas, one neurilemoma, one arachnoid cyst, and one metastasis of breast cancer. Well-resolved H-1 MR spectra of these tumors were obtained in vivo with a conventional 1.5-T whole-body MR imaging system. All tumor spectra were remarkably different from spectra from normal brain tissue. Spectra obtained from different tumors exhibited reproducible differences, while histologically similar tumors yielded characteristic spectra with only minor differences. The observed spectral alterations reflect variations in concentrations and relaxation times of the H-1 MR sensitive pool of free (mobile) metabolites within the tissues. In most cases, the concentrations of N-acetyl-aspartate and creatine/phosphocreatine are reduced below detectability, whereas choline-containing compounds are generally enhanced. The spectral differences between the tumors are mainly due to the differing concentrations of lipids, lactic acid, and carbohydrates. Localized H-1 MR spectroscopy may become an important clinical tool for the differentiation of tumors as well as for therapeutic control.     

儿科哮喘临床治疗的研究进展

儿童过敏性疾病包括很多种,过去几年其发病率在发达国家有所上升.这类疾病是一些有遗传倾向的儿童受环境因素而诱发,而现在对于这些环境因素仍不完全清楚.异位三合症（atopic triad）通常是指异位性皮炎、过敏性鼻炎和哮喘,患者常同时出现三种疾病的症状,并且一般由最初的异位性皮炎和食物过敏发展到过敏性鼻炎、环境过敏症和哮喘,我们将此过程称之为“遗传性过敏症进行曲”（atopic march）.     

Effect of LVAD outflow conduit insertion angle on flow through the native aorta

Background and aim: The goal of this study was to evaluate the effect of surgical anastomosis configuration of the aortic outflow conduit (AOC) from a continuous flow left ventricular assist device (LVAD) on the flow fields in the aorta using CFD simulations. The geometry of the surgical integration of the LVAD is an important factor in the flow pattern that develops both in series (aortic valve closed, all flow through LVAD) and in parallel (heart pumping in addition to LVAD).

Methods: CFD models of the AOC junctions simulate geometry as cylindrical tubes that intersect at angles ranging from 30° to 90°. Velocity fields are computed over a range of cardiac output for both series and parallel flow.

Results: Our results demonstrate that the flow patterns are significantly affected by the angle of insertion of the AOC into the native aorta, both during series and parallel flow conditions. Zones of flow recirculation and high shear stress on the aortic wall can be observed at the highest angle, gradually decreasing in size until disappearing at the lowest angle of 30°. The highest velocity and shear stress values were associated with series flow.

Conclusions: The results suggest that connecting the LVAD outflow conduit to the proximal aorta at a shallower angle produces fewer secondary flow patterns in the native cardiovascular system.     

Unequal crossing-over: a common basis of single alpha-globin genes in Asians and American blacks with hemoglobin-H disease

The alpha-globin genes of five black Americans, two Chinese, and five Filipinos with HbH disease (an alpha-thalassemia state in which there is a single functional alpha gene) were analyzed by restriction endonuclease techniques. All subjects were found to have one chromosome 16, lacking both alpha genes, and another containing a single alpha gene (--/-alpha). Restriction endonuclease patterns of the DNA obtained from all 12 subjects were identical and compatible with unequal crossing-over as the mechanism of origin of the single alpha gene in these individuals.     

Intravenous infusion for the treatment of diabetic and ischaemic non-healing pedal ulcers

Diabetic and ischaemic non-healing pedal ulcers have a tendency for chronicity and increased chances of infection, which may threaten the viability of the foot. Systemic administration of therapeutic agents may be insufficient in these cases. We have assessed the role of retrograde venous perfusion (RVP) for the treatment of nine diabetic and 10 ischaemic non-healing pedal ulcers. Agents used were soda bicarbonate, heparin, lignocaine, gentamicin and pentoxiphylline. Five of nine diabetic non-healing ulcers showed complete healing and the remaining four improved. The complete recovery in the cases of diabetic ulcer occurred in 10-24 days (mean 16 days), while ischaemic ulcers took 10-14 days for complete recovery (mean 13.6 days). There was a reduction of rest pain in all 10 patients with ischaemic disease; five patients showed complete healing of ulcers, and the other five improved significantly. In two patients, pre-gangrene changes were reversed. RVP is a useful adjunct to conservative or surgical treatment of non-healing pedal ulcers. Its main impact was in improving ischaemia and promoting healing.