Brain tumors in children. I. Advances in diagnosis

This article emphasizes the contributions that new diagnostic techniques have made toward the management of children with brain tumors. The development of computerized tomographic (CT) scanning has revolutionized both the diagnosis and management of patients with brain tumors and has obviated the previously inevitable delays in diagnosis. The development of magnetic resonance imaging (MRI) has certainly facilitated diagnosis of brain tumors in certain locations with the brain, but it remains unproven in other locations. It is clear that at least some of the early promise of MRI scanning has not been realized. Neither CT nor MRI are able to provide functional detail within the brain, nor are they able to differentiate tumor from peritumoral edema to better delineate the tumor margins. It is hoped that the currently experimental techniques of Positron Emission Tomography (PET) scanning and contrast-enhanced MRI scanning will provide such information in the near future. Neurophysiologic methods of assessing brain tumors merit greater consideration than has been afforded to date. Sensory evoked-potential monitoring provides information about nervous system function. This information is useful both in diagnosis and in monitoring of brain tumors, since the functional information can be localized to discrete regions within the brain. The value of cerebrospinal fluid (CSF) evaluation, both for cytology and tumor markers, cannot be overstated. A significant proportion of childhood brain tumors tend to seed throughout the neuraxis by the CSF pathways. Thus, evaluation of CSF cytology prior to surgical perturbation of the primary tumor should be undertaken whenever safely feasible, in order to avoid the dilemma of postoperative positive CSF cytology and its questionable significance.     

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

In-vivo comparison of four absorbable sutures: Vicryl, Dexon Plus, Maxon and PDS

Absorbable sutures are initially equal or superior to nonabsorbable sutures in terms of tensile strength but are absorbed at variable rates by the action of hydrolysis. This study demonstrated that the in-vivo half-life tensile strength of the braided absorbable sutures polyglycolic acid (Dexon Plus) and polyglactin 910 (Vicryl) is 2 weeks, whereas those of the monofilament absorbable sutures polyglyconate (Maxon) and polydioxanone (PDS) are 3 and 6 weeks respectively. The addition of a single hitch or six knots reduced the in-vitro tensile strength by 30% to 35%. Polyglyconate (Maxon) suture demonstrated the best in-vitro knot security.     

Stability of the original Hoffmann and AO tubular external fixation devices

Detailed data of the stability of external fixation devices are needed by the orthopaedic surgeon to predict successful healing of a fracture. The stability (rigidity, yield and failure criteria) of four half-frame configurations (single, stacked, double and delta) of the original Hoffmann and AO tubular frame have been analysed under four loading conditions: axial compression, torsion, and both AP- and ML-bending. Overall the two systems' rigidities were the same between similar configurations. Both systems' single half-frames were particularly weak; however, as the number of components (rods, pins, clamps, couplings) on the frame increased, the rigidity of the frame increased. The difference in performance between the two systems lies in their yield and failure characteristics. The AO system exhibited excellent failure criteria in all modes of loading, i.e. no configuration failed within the test limits, whereas most Hoffman frames yielded and failed at low loads.     

Classical and anaplastic seminoma: difference in survival

Classical and anaplastic seminoma are traditionally treated with radiation therapy and are said to have the same prognosis. A retrospective study was undertaken of 90 seminoma patients treated with radiation therapy between 1961 and 1985. The classical group consisted of 71 patients of whom 50 had stage I and 21 had stage II disease. The anaplastic group consisted of 19 patients of whom ten had stage I and nine had stage II disease. The median follow-up time was 64 months for the entire group. The 10-year relapse-free survival rate for the classical group was 94% and for the anaplastic group was 70% (P less than .05). For patients with classical stage I disease, the relapse-free actuarial survival rate was 98%; for patients with anaplastic stage I disease, it was 64% (P less than .02). For the classical stage II disease group, the relapse-free actuarial survival rate was 84% and for the anaplastic stage II disease group, 75% (P less than .70). Four patients in the classical group (6%) had relapses; of these, one patient had local recurrence of tumor, and three had distant metastases. In the anaplastic group, four patients (21%) had relapses; two patients had local recurrence of tumor, and two had distant metastases. Therefore the data suggest a difference in survival and relapse rates between classical and anaplastic seminoma.     

Cytokinetic factors in drug resistance of Lewis lung carcinoma: comparison of cells freshly isolated from tumours with cells from exponential and plateau-phase cultures.

The cytotoxic effects of chemotherapeutic drugs on quiescent and actively proliferating cells of a Lewis lung carcinoma (LLTC) cell line have been examined. The sensitivities of cells in plateau-phase and exponentially growing cultures were compared with those of cells recovered from large subcutaneous tumours both immediately after tumour disaggregation and after one or 4 days in culture. Flow cytometric analysis indicated that when cells freshly prepared from tumours were placed into culture, they underwent extensive recruitment into S-phase. Several drugs were less cytotoxic towards both plateau-phase cultured cells and cells freshly isolated from tumours than they were against exponentially growing cells. These included amsacrine, its 4-methyl-5-(N-methyl)carboxamide derivative CI-921, doxorubicin, and nitrogen mustard. In contrast to these drugs, chlorambucil and plasma from cyclophosphamide-treated mice did not show decreased activity against slowly proliferating cells from cultures or tumours relative to cells in an actively proliferating state. The similar sensitivities of plateau-phase cultured cells and cells taken directly from large growing tumours is direct evidence that plateau-phase cultures are a useful approximation to the state of cytokinetic resistance to chemotherapeutic drugs that prevails in solid tumours, although they may not fully reflect the cytokinetic heterogeneity present in tumours.