Potent cytotoxicity of an antihuman transferrin receptor-ricin A-chain immunotoxin on human glioma cells in vitro

The cytotoxic effects of an antihuman transferrin receptor monoclonal antibody-ricin A-chain conjugate (anti-TfR-A) immunotoxin on glioma cells were assessed in vitro. Five human glioma cell lines were studied; three were derived from surgical explants (MG-1, MG-2, MG-3) and two were well characterized established glioma cells (U-87 MG, U-373 MG). The C6 rat glioma line served as a nonhuman control. One of six lines (U-373) expressed glial fibrillary acidic protein, as assessed by immunohistochemistry. All five human lines expressed human transferrin receptor, as assessed by flow cytometry; no human transferrin receptor was demonstrable on rat C6 cells. Potent inhibition of protein synthesis was found after an 18-h incubation with anti-TfR-A. Fifty % inhibitory concentration (IC50) values for human glioma cells ranged from 1.9 X 10(-9) to 1.8 X 10(-8) M. In contrast, no significant inhibition of leucine incorporation was observed when anti-TfR-A was tested on rat cells (IC50 greater than 10(-7) M) or when a control immunotoxin directed against carcinoembryonic antigen was substituted for anti-TfR-A on human glioma cells (IC50 greater than 10(-7) M). Coincubation with the carboxylic ionophore monensin (10(-7) M) decreased the IC50 of anti-TfR-A against human glioma lines from 16- to 842-fold (range, 7.0 X 10(-12) to 1.5 X 10(-10) M). In contrast, an IC50 of greater than 10(-7) M was obtained when C6 cells were incubated with anti-TfR-A and monensin. Anti-TfR-A immunotoxins potentiated by monensin are extremely potent in vitro cytotoxins for human glioma cells

Quantitative analysis of the loss of distinction between gray and white matter in comatose patients after cardiac arrest

BACKGROUND AND PURPOSE: Anecdotal reports suggest that a loss of distinction between gray (GM) and white matter (WM) as adjudged by CT scan predicts poor outcome in comatose patients after cardiac arrest. To address this, we quantitatively assessed GM and WM intensities at various brain levels in comatose patients after cardiac arrest. METHODS: Patients for whom consultation was requested within 24 hours of a cardiac arrest were identified with the use of a computerized database that tracks neurological consultations at our institution. Twenty-five comatose patients were identified for whom complete medical records and CT scans were available for review. Twenty-five consecutive patients for whom a CT scan was interpreted as normal served as controls. Hounsfield units (HUs) were measured in small defined areas obtained from axial images at the levels of the basal ganglia, centrum semiovale, and high convexity area. RESULTS: At each level tested, lower GM intensity and higher WM intensity were noted in comatose patients compared with normal controls. The GM/WM ratio was significantly lower among comatose patients compared with controls (P:\u3c0.0001, rank sum test). There was essentially no overlap in GM/WM ratios between control and study patients. The difference was greatest at the basal ganglia level. We also observed a marginally significant difference in the GM/WM ratio at the basal ganglia level between those patients who died and those who survived cardiac arrest (P:=0. 035, 1-tailed t test). Using receiver operating characteristic curve analysis, we determined that a difference in GM/WM ratio of \u3c1.18 at the basal ganglia level was 100% predictive of death. At the basal ganglia level, none of 12 patients below this threshold survived, whereas the survival rate was 46% among patients in whom the ratio was \u3e1.18. The empirical risk of death was 21.67 for comatose patients with a value below threshold. CONCLUSIONS: The ratio in HUs of GM to WM provides a reproducible measure of the distinction between gray and white matter. A lower GM/WM ratio is observed in comatose patients immediately after cardiac arrest. The basal ganglia level seems to be the most sensitive location on CT for measuring this relationship. Although a GM/WM ratio \u3c1.18 at this level predicted death in this retrospective study, the difference in this study is not robust enough to recommend that management decisions be dictated by CT results. The results, however, do warrant consideration of a prospective study to determine the reliability of CT scanning in predicting outcome for comatose patients after cardiac arrest

TrkA expression decreases the in vivo aggressiveness of C6 glioma cells

We stably expressed the nerve growth factor receptor trkA or a truncated trkA lacking the kinase domain (trkA delta) in a highly tumorigenic rat glioma cell line, C6. Survival of rats with large intrastriatal inocula of C6trkA cells was significantly longer than for rats bearing C6 or C6trkA delta cells. Histological studies revealed that C6trkA cells were much less invasive than C6 or C6trkA delta cells and had a greater rate of apoptosis. There was no apparent induction of differentiation of C6 cells by trkA. Therefore, unlike what is observed in neuroblastomas, trkA decreases tumorigenicity by modulating invasiveness and tumor cell death independent of inducing differentiation. This novel mechanism suggests a new therapeutic strategy for malignant gliomas

Brain tumor presenting as an acute pure motor hemiparesis

Acute pure motor hemiparesis is a clinical syndrome of isolated hemiparesis usually related to lacunar infarction, although other etiologies have been described. We recently encountered three patients with the abrupt onset of pure motor hemiparesis as the initial manifestation of primary or metastatic brain tumor. In each patient, early computed tomography demonstrated a nonhemorrhagic, right frontal, enhancing mass lesion. While the mechanism whereby brain tumor may present abruptly and simulate a stroke remains uncertain, these cases illustrate that pure motor hemiparesis can be the initial symptom of intracranial tumor. Early computed tomography or magnetic resonance imaging is suggested for all patients who present acutely with pure motor hemiparesis

Cortical blindness after correction of symptomatic hyponatremia: dynamic cerebral dysfunction visualized using serial SPECT scanning

A 70-yr-old woman developed cortical blindness after correction of hyponatremia. Regional hyperperfusion was noted on SPECT scans obtained in the acute phase. One month later when symptoms had largely resolved, a repeat examination was normal. This regional hyperperfusion, which was not associated with any apparent structural damage, may have represented either luxury perfusion or a transient increased metabolic requirement of the dysfunctional cortical area. SPECT scanning may be a useful method to study cerebral dysfunction resulting from an osmotic disturbance

The rationale for early detection and treatment of brain tumors in survivors of childhood cancer

Survivors of childhood cancer have a relatively high risk of developing second cancers. The incidence of brain tumor in these patients approaches 1% at 10 years, over 80-fold that in the general population. This high incidence increases the likelihood that early detection of brain tumors in survivors of childhood cancer is feasible. By analogy with other epithelial cancers, detection and treatment of brain tumors at a pre-neoplastic or premalignant stage may render screening and treatment cost effective for certain high-risk populations. Our animal studies with a clinically appropriate model of this condition suggest that there is a pre-neoplastic, pre-malignant brain tumor lesion that is potentially both detectable and effectively treated. The possibility of detecting such a treatable antecedent to brain tumors provides the rationale for genomic and proteomic screening of tumor tissue, CSF, plasma and urine in this animal model, of tumor tissue and body fluids of patients with known brain tumors at various stages, and of body fluids of survivors of childhood cancer

Embryonic precursor cells that express Trk receptors: induction of different cell fates by NGF, BDNF, NT-3, and CNTF

Epidermal growth factor (EGF)-treated neurosphere cultures from embryonal striatum contain multipotential cells capable of neuronal, astrocytic, and oligodendroglial differentiation. In this study, we tested whether these neural precursor cells differentiate in the presence of neurotrophic factors. We first assayed neurosphere cells for expression of neurotrophin receptors. TrkA, TrkB, TrkC, and gp75 were detected by immunofluorescence microscopy in 60-80% of cells. In addition, the ciliary neurotrophic factor receptor alpha was expressed in 50-60% of cells. In the presence of the mitogen, EGF, treatment of stem cells with neurotrophic factors had no apparent effect. Removal of EGF from cells resulted in cessation of cell proliferation and pronounced astrocytic (glial fibrillary acidic protein+) differentiation. Neuronal (neurofilament+) and oligodendroglial (galactocerebroside+) cells appeared in cultures treated with neurotrophic factors. Nerve growth factor (NGF) resulted in bipolar neuronal cells, and brain-derived neurotrophic factor led to multipolar neuronal cells. Treatment with neurotrophin-3 or ciliary neurotrophic factor resulted in bipolar neuronal cells and oligodendrocytes. Neuronal differentiation in the presence of NGF was enhanced by extracellular matrix, and the resulting neuronal cells expressed choline acetyltransferase and, to a lesser degree, tyrosine hydroxylase. These studies demonstrate that neurotrophic factors influence the fates of these multipotential precursor cells. Indeed, the true utility of multipotential precursor cells is the production of different types of cells in different situations. Local cues, such as neurotrophic factors and extracellular matrix, may regulate production of different types of neural cells during development or in response to other stimuli, such as injury