Biomedical subjects

E Hug

Publications and source records attributed to E Hug.

17 recordsLinked to original sources

PubMed1999

Analysis of the relationship between tumor dose inhomogeneity and local control in patients with skull base chordoma.

PURPOSE: When irradiating a tumor that abuts or displaces any normal structures, the dose constraints to those structures (if lower than the prescribed dose) may cause dose inhomogeneity in the tumor volume at the tumor-critical structure interface. The low-dose region in the tumor volume may be one of the reasons for local failure. The aim of this study is to quantitate the effect of tumor dose inhomogeneity on local control and recurrence-free survival in patients with skull base chordoma. METHODS AND MATERIALS: 132 patients with skull base chordoma were treated with combined photon and proton irradiation between 1978 and 1993. This study reviews 115 patients whose dose-volume data and follow-up data are available. The prescribed doses ranged from 66.6 Cobalt-Gray-Equivalent (CGE) to 79.2 CGE (median of 68.9 CGE). The dose to the optic structures (optic nerves and chiasm), the brain stem surface, and the brain stem center was limited to 60, 64, and 53 CGE, respectively. We used the dose-volume histogram data derived with the three-dimensional treatment planning system to evaluate several dose-volume parameters including the Equivalent Uniform Dose (EUD). We also analyzed several other patient and treatment factors in relation to local control and recurrence-free survival. RESULTS: Local failure developed in 42 of 115 patients, with the actuarial local control rates at 5 and 10 years being 59% and 44%. Gender was a significant predictor for local control with the prognosis in males being significantly better than that in females (P = 0.004, hazard ratio = 2.3). In a Cox univariate analysis, with stratification by gender, the significant predictors for local control (at the probability level of 0.05) were EUD, the target volume, the minimum dose, and the D5cc dose. The prescribed dose, histology, age, the maximum dose, the mean dose, the median dose, the D90% dose, and the overall treatment time were not significant factors. In a Cox multivariate analysis, the models including gender and EUD, or gender and the target volume, or gender and the minimum target dose were significant. The more biologically meaningful of these models is that of gender and EUD. CONCLUSION: This study suggests that the probability of recurrence of skull base chordomas depends on gender, target volume, and the level of target dose inhomogeneity. EUD was shown to be a useful parameter to evaluate dose distribution for the target volume.

Adult↗

PubMed1998

Temporal lobe (TL) damage following surgery and high-dose photon and proton irradiation in 96 patients affected by chordomas and chondrosarcomas of the base of the skull.

PURPOSE: To determine the temporal lobe (TL) damage rate in 96 patients treated with high-dose proton and photon irradiation for chordomas and chondrosarcomas of the base of the skull. METHODS AND MATERIALS: The records of 96 consecutive patients treated at Massachusetts General Hospital (MGH) and Harvard Cyclotron Laboratory (HCL) between June 1984 and 1993, for chordomas and chondrosarcomas of the base of the skull were reviewed. All the patients had undergone some degree of resection of the tumor prior to radiation therapy. Seventy-five patients were classified as "primary tumors" and 21 as recurrent or regrowing tumors after one or more surgical procedures. All the patients were randomized to receive 66.6 or 72 cobalt Gray equivalent (CGE) on a prospective dose-searching study by proton and photon irradiation (Radiation Therapy Oncology Group #85-26) with conventional fractionation (1.8 CGE/day, 5 fractions/week). All treatments were planned using the three-dimensional (3D) planning system developed at the Massachusetts General Hospital, and the dose was delivered using opposed lateral fields for the photon component and a noncoplanar isocentric technique for the proton component. Clinical symptoms of TL damage were classified into 4 grades. Computerized tomography (CT) and magnetic resonance imaging (MRI) scans were evaluated for white matter changes. Abnormalities associated with persistent or recurrent tumor were distinguished from radiation-induced changes. TLs were delineated on the original scans of the 10 patients with damage and those of a group of 33 patients with no clinical or MRI evidence of injury. Dose distributions were calculated and dose-volume histograms were obtained for these patients. RESULTS: Of the patients, 10 developed TL damage, with bilateral injury in 2 and unilateral injury in 8. The cumulative TL damage incidence at 2 and 5 years was 7.6 and 13.2%, respectively. The MRI areas suggestive of TL damage were always separated from the tumor bed. Symptoms were severe to moderate in 8 patients. Several baseline factors, tumor- or host-related, were analyzed to evaluate their predictivity for TL damage: age, gender, tumor site, histology, type of presentation, type and number of surgical procedures, primary tumor volume, prescribed dose, normal tissue involvement, and volume of TL receiving doses ranging between 10 and 50 CGE or more. Only gender, in a univariate analysis (log rank) was a significant predictor of damage (0.0155), with male patients being at significantly higher risk of TL injury. In a stepwise Cox regression that included gender as a variable, no other baseline variable improved the prediction of damage. CONCLUSIONS: The 2- and 5-year cumulative TL damage rates were 7.6 and 13.2%, respectively. Despite the different TL damage rates related to age, tumor volume, number of surgical procedures prior to radiation therapy, and prescribed doses to the tumor, only gender was a significant predictor of damage (p = 0.0155) using a univariate (log rank) test. Chordomas and chondrosarcomas of the base of the skull may represent an interesting model to evaluate the TL damage rates because of their extradural origin, displacing the white matter instead of infiltrating it as gliomas do, because of their longer local recurrence-free survival other than gliomas and other brain tumors and because of the high doses of irradiation delivered to the target volume to obtain local control.

Adolescent↗

PubMed1994

Thymoma. Histologic subclassification is an independent prognostic factor.

BACKGROUND: Several histologic classifications of thymomas have been proposed, and attempts have been made to correlate the different histologic subtypes to clinical behavior and prognosis. Recently, Marino and Müller-Hermelink and Kirchner et al. proposed a new morphologic classification of thymomas based on the resemblance of the neoplastic cells to subtypes of the normal thymic epithelial cells. In this classification, six categories of thymic epithelial tumors are recognized. They define four categories of thymoma: medullary, mixed, organoid (predominantly cortical), and cortical, and two subgroups of thymic carcinomas: well differentiated thymic carcinoma and high grade carcinomas. METHODS: The authors studied 116 patients with thymic epithelial tumors classified according to the proposals of Marino and Müller-Hermelink and Kirchner et al. to assess the effect of histologic classification and other factors (stage, size of tumor, lymphoid hyperplasia, myasthenia gravis, age, sex, and treatment) on survival, and freedom from relapse. RESULTS: Eight cases (7%) were medullary, 32 cases (28%) mixed, 20 cases (17%) organoid (predominantly cortical), 21 cases (18%) cortical, 29 cases (25%) well differentiated carcinoma (WDTC), two cases (2%) high grade carcinoma, and four cases (3%) unclassifiable. Fifty-two patients were in stage I, 32 stage II (16 IIA, 16 IIB), 28 stage III, and four Stage IVA. Only stage (P = 0.0001; hazard ratio = 5.36) and histology (P = 0.0019; hazard ratio = 8.010) were significant in predicting recurrence. Histology was highly correlated with stage, but by multivariate analysis was an independent factor in predicting relapse (P = 0.0281; hazard ratio = 5.92). None of the medullary or mixed thymomas recurred, even though 30% were invasive. Patients with WDTC recurred more often and earlier than patients with organoid and cortical thymoma (log rank, P = 0.0001). The actuarial freedom from relapse for patients with WDTC was 58% at 5 years and 46% at 10 years compared with 100% for other subtypes. Both advanced stage (III and IV) and the WDTC histologic subtype significantly increased the risk of death from thymoma (log rank, P = 0.0001). The actuarial survival of patients with WDTC was 80% at 5 years and 54% at 10 years, whereas that of patients with the other subtypes was 100% at 5 and 10 years. Five of seven relapses and six of seven deaths from thymoma occurred in patients with WDTC. In Stage II patients, one of 16 minimally invasive (Stage IIA) tumors recurred, compared with 3 of 16 grossly invasive (Stage IIB) tumors, indicating that microscopic assessment of invasion is important in staging. CONCLUSIONS: The histologic classification of Marino and Müller-Hermelink has prognostic significance, independent of tumor stage. Medullary and mixed thymomas were benign tumors with no risk of recurrence, even when capsular invasion was present. Organoid and cortical thymoma showed intermediate invasiveness and a low, but significant, risk of late relapse, even with minimal invasion. WDTC were always invasive and had a significantly increased risk of relapse and death, even for Stage II patients. Adjuvant therapy appears unnecessary for medullary and mixed thymomas, even when invasive.

Adolescent↗

PubMed1992

Autoreactivity of low but not of high CD4 variants of an antigen-specific, I-A-restricted mouse T cell clone.

Variant lines expressing high and low surface densities of the accessory molecule CD4 have been developed by repeated preparative flow cytometric cell sortings from the murine Th cell clone D10.G4.1 (D10). The high CD4 variant line (D10H) fully maintained the original I-Ak restricted specificity for conalbumin of wild-type D10 cells. In contrast, the low CD4 variant line (D10L) showed a strong autoreactivity to I-Ak carrying stimulator cells alone which was only slightly augmented by addition of conalbumin. Cell surface molecules other than CD4, including TCR, CD3, CD11a, CD2, CD45, CD44, and MHC class I, remained identical on D10H and D10L sublines as on D10 wild-type cells. The possibility that D10L cells had suffered alterations of their TCR-alpha beta was excluded by demonstrating their reactivity with a panel of eight different anti-clonotypic mAb specific for various epitopes of the D10 TCR. By limiting dilution analysis we show that the majority of responding cells of D10L sublines were autoreactive. Although the reactivity for allogeneic I-A also increased as compared with D10H cells, a clear preference for self-I-Ak was maintained so that a true autoreactive phenotype was evident. The results indicate that the surface concentration of CD4 has a decisive influence on self-non-self discrimination of MHC class II-restricted Th cells.

Animals↗

PubMed1988

Cloned Listeria monocytogenes specific non-MHC-restricted Lyt-2+ T cells with cytolytic and protective activity.

Mice were infected with Listeria monocytogenes and Lyt-2+ T cell clones capable of lysing Ag-primed bone marrow macrophages were established. In accordance with earlier findings obtained at the population level, some T cell clones were identified which lysed bone marrow macrophages of different MHC type provided the relevant Ag was present. This unusual target cell recognition was further analyzed using a T3+, L3T4-, Lyt-2+, F23+, KJ16+ T cell clone, designated L-28. Target cell lysis by this clone was Ag specific, apparently non-MHC restricted. In contrast, YAC cells and P815 cells were not lysed by clone L-28. However, lysis of irrelevant targets could be induced by anti-T3, F23, or KJ16 mAb. Furthermore, Ag-specific lysis was blocked by anti-Lyt-2 mAb and by F(ab)2 fragments of F23 mAb. In addition to its cytolytic activity, clone L-28 produced IFN-gamma after co-stimulation with accessory cells, Ag, and rIL-2 and conferred significant protection on recipient mice when given together with rIL-2. These data suggest that non-MHC-restricted Lyt-2+ killer cells generated during listeriosis are cytolytic T lymphocytes that interact with their target Ag via the T cell receptor/T3 complex and the Lyt-2 molecule and, furthermore, that these cells play a role in anti-listerial resistance. The possible relevance of IFN-gamma secretion and target cell lysis for antibacterial protection is discussed.

Animals↗

PubMed1987

Specific lysis of Listeria monocytogenes-infected macrophages by class II-restricted L3T4+ T cells.

Mice were infected with the intracellular bacterium, Listeria monocytogenes, and T cell clones from spleens, lymph nodes and peritoneal exudates were established. The capacity of L3T4+, Lyt2- T-cell clones to specifically lyse L. monocytogenes-infected macrophages was analyzed. As a source of target cells, bone marrow macrophages (BMM phi) after 9 days of culture in hydrophobic teflon bags were used. These BMM phi were totally Ia-; however, significant Ia-expression could be induced by interferon-gamma (IFN-gamma). IFN-gamma-stimulated BMM phi, after priming with live or killed L. monocytogenes organisms were effectively lysed by the vast majority of L3T4+ T cell clones. In the absence of either IFN-gamma stimulation or antigen priming, no lysis occurred. Cytolysis was demonstrable in a conventional 4-h 51Cr-release assay and in an 18-h neutral red uptake assay and was antigen specific and class II restricted. Native T cells from L. monocytogenes-infected mice failed to lyse stimulated, L. monocytogenes-primed BMM phi and gained their cytolytic activity after antigenic restimulation in vitro. These data demonstrate that L. monocytogenes-specific L3T4+ T cells could lyse M phi presenting listerial antigens provided that Ia antigen expression had been induced. L3T4+ T cell clones produced IFN-phi after restimulation with antigen plus accessory cells in vitro and IFN-gamma secretion could be increased by costimulation with recombinant IL 2. These T cell clones conferred significant protection upon recipient mice which was more pronounced in the liver. The possible relevance of lysis by L3T4+ T cells of infected M phi to protection against and pathogenesis of intracellular bacterial infections is discussed.

Animals↗

PubMed1986

Listeria monocytogenes-reactive T lymphocyte clones with cytolytic activity against infected target cells.

Lyt-2+ T cell clones were established from Listeria monocytogenes-infected mice. The clones secreted IFN-gamma after stimulation with spleen cells from L. monocytogenes-infected mice plus IL-2. Spleen cells from normal mice were not stimulatory. Furthermore, cloned T cells lysed L. monocytogenes-infected macrophages. Cytolysis was antigen-specific and H-2K-restricted. These findings suggest a role for specific cytotoxic T cells in the immune response to intracellular bacteria.

Animals↗

PubMed1986

Ouabain binding and inotropy in acute potassium depletion in guinea pigs.

In hypokalaemia the incidence of cardiac toxicity with digitalis is increased, possibly through changes in the affinity or capacity of the digitalis receptor in the heart. Previous studies have reported an increased ouabain binding capacity or Na+-K+ ATPase activity after hypokalaemia in human erythrocytes and rabbit and guinea pig hearts and no change or decreases in rabbit or rat skeletal muscles with no changes in ouabain affinity. The present study determined (a) the effect of potassium on 3H-ouabain binding to normokalaemic guinea pig cardiac cell membranes, (b) the effect of acute hypokalaemia induced by a potassium deficient diet for 14-18 days in guinea pigs on 3H-ouabain binding to erythrocytes and cardiac and skeletal muscle homogenates, and (c) ouabain induced inotropy in isolated contracting guinea pig left atria, right ventricular papillary muscles, and soleus muscle strips from normokalaemic and hypokalaemic guinea pigs. 3H-ouabain binds to cardiac cell membranes in the presence of magnesium and inorganic phosphate with an affinity (KD value) of 1.13 X 10(-7) mol X litre-1. Potassium decreased this affinity without changing the binding capacity. Erythrocytes and heart muscle homogenates showed the same affinity as cardiac cell membranes, whereas soleus muscle homogenates had a higher affinity for ouabain (KD 5.1 X 10(-8) mol X litre-1). After hypokalaemia, the ouabain affinity did not change in any tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Comparison of ouabain receptors in sheep myocardium and Purkinje fibres.

The conducting system of the heart has been reported to be more sensitive to the toxic effects of digitalis than the working myocardium. To investigate the molecular basis of these observations, we have characterized the ouabain receptor in Purkinje fibres and ventricular muscle of the digitalis-sensitive sheep heart using cell membrane preparations, crude homogenates and contracting heart tissues. [3H]-Ouabain binding has the following characteristics: in sheep left ventricular cell membranes, specific binding was of high affinity (KD 1.9 X 10(-9) M at 37 degrees); was co-incident with an inhibition of (Na+ + K+)-ATPase activity; and was inhibited by K+ and unlabelled cardiotonic steroids; in crude homogenates, the maximal binding capacity but not the affinity for ouabain varied in different parts of the sheep heart with Purkinje fibres containing markedly fewer binding sites (0.33 X 10(14)/g wet weight; left ventricle, 1.3 X 10(14)/g wet weight) and in isolated, contracting Purkinje fibres and right ventricular moderator band strips, concentration-response curves for [3H]-ouabain binding, increase in force of contraction and inhibition of [86Rb+]-uptake were co-incident. In both contracting tissues, a ouabain concentration of 3 X 10(-7) M occupied about 50% of the specific binding sites, gave the maximal inotropic effect without toxicity and inhibited [86Rb+]-uptake by about 50%. The maximal binding capacity was lower in contracting Purkinje fibres (2 X 10(14) binding sites/g wet weight) than in contracting moderator band strips (3.9 X 10(14) binding sites/g wet weight). The maximal inotropic effects were reached slightly faster in Purkinje fibres but toxicity also occurred faster in these fibers. We conclude that the specific ouabain binding site is the receptor mediating positive inotropy and inhibition of (Na+ + K+)-ATPase in the sheep heart. Further, this receptor is identical in both the conducting system and working myocardium but the conducting system contains many fewer receptors. This change in receptor number, rather than affinity, may underlie the increased ouabain toxicity observed in Purkinje fibres.

Animals↗

PubMed1985

Effective protection against Listeria monocytogenes and delayed-type hypersensitivity to listerial antigens depend on cooperation between specific L3T4+ and Lyt 2+ T cells.

Selected L3T4- and Lyt 2- T-cell subpopulations from Listeria monocytogenes-infected mice were transferred into syngenic recipients, and their capacity to adoptively mediate protection against L. monocytogenes and delayed-type hypersensitivity to listerial antigens was determined. Both functions were markedly reduced by pretreatment of cells with either anti-L3T4 or anti-Lyt 2.2 antibodies plus complement, but they could be restored by admixture of the two selected T-cell subsets. Thus, after systemic cell transfer effective protection against L. monocytogenes and delayed-type hypersensitivity to listerial antigens depend on cooperation between specific L3T4+ and Lyt 2+ T cells.

Animals↗

PubMed1978