Glial neoplasms: dynamic contrast-enhanced T2*-weighted MR imaging

PURPOSE

To evaluate the role of T2*-weighted echo-planar perfusion imaging by using a first-pass gadopentetate dimeglumine technique to determine the association of magnetic resonance (MR) imaging-derived cerebral blood volume (CBV) maps with histopathologic grading of astrocytomas and to improve the accuracy of targeting of stereotactic biopsy.

MATERIALS AND METHODS

MR imaging was performed in 29 patients by using a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence followed by conventional imaging. The perfusion data were processed to obtain a color map of relative regional CBV. This information formed the basis for targeting the stereotactic biopsy. Relative CBV values were computed with a nondiffusible tracer model. The relative CBV of lesions was expressed as a percentage of the relative CBV of normal white matter. The maximum relative CBV of each lesion was correlated with the histopathologic grading of astrocytomas obtained from samples from stereotactic biopsy or volumetric resection.

RESULTS

The maximum relative CBV in high-grade astrocytomas (n = 26) varied from 1.73 to 13.7, with a mean of 5.07 +/- 2.79 (+/- SD), and in the low-grade cohort (n = 3) varied from 0.92 to 2.19, with a mean of 1.44 +/- 0.68. This difference in relative CBV was statistically significant (P < .001; Student t test).

CONCLUSION

Echo-planar perfusion imaging is useful in the preoperative assessment of tumor grade and in providing diagnostic information not available with conventional MR imaging. The areas of perfusion abnormality are invaluable in the precise targeting of the stereotactic biopsy.

Deep-Learning Convolutional Neural Networks Accurately Classify Genetic Mutations in Gliomas

BACKGROUND AND PURPOSE

The World Health Organization has recently placed new emphasis on the integration of genetic information for gliomas. While tissue sampling remains the criterion standard, noninvasive imaging techniques may provide complimentary insight into clinically relevant genetic mutations. Our aim was to train a convolutional neural network to independently predict underlying molecular genetic mutation status in gliomas with high accuracy and identify the most predictive imaging features for each mutation.

MATERIALS AND METHODS

MR imaging data and molecular information were retrospectively obtained from The Cancer Imaging Archives for 259 patients with either low- or high-grade gliomas. A convolutional neural network was trained to classify isocitrate dehydrogenase 1 (IDH1) mutation status, 1p/19q codeletion, and O6-methylguanine-DNA methyltransferase (MGMT) promotor methylation status. Principal component analysis of the final convolutional neural network layer was used to extract the key imaging features critical for successful classification.

RESULTS

Classification had high accuracy: IDH1 mutation status, 94%; 1p/19q codeletion, 92%; and MGMT promotor methylation status, 83%. Each genetic category was also associated with distinctive imaging features such as definition of tumor margins, T1 and FLAIR suppression, extent of edema, extent of necrosis, and textural features.

CONCLUSIONS

Our results indicate that for The Cancer Imaging Archives dataset, machine-learning approaches allow classification of individual genetic mutations of both low- and high-grade gliomas. We show that relevant MR imaging features acquired from an added dimensionality-reduction technique demonstrate that neural networks are capable of learning key imaging components without prior feature selection or human-directed training.

Differentiation of glioblastoma multiforme and single brain metastasis by peak height and percentage of signal intensity recovery derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging

BACKGROUND AND PURPOSE

Glioblastoma multiforme (GBM) and single brain metastasis (MET) are the 2 most common malignant brain tumors that can appear similar on anatomic imaging but require vastly different treatment strategy. The purpose of our study was to determine whether the peak height and the percentage of signal intensity recovery derived from dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion MR imaging could differentiate GBM and MET.

MATERIALS AND METHODS

Forty-three patients with histopathologic diagnosis of GBM (n=27) or MET (n=16) underwent DSC perfusion MR imaging in addition to anatomic MR imaging before surgery. Regions of interest were drawn around the nonenhancing peritumoral T2 lesion (PTL) and the contrast-enhancing lesion (CEL). T2* signal intensity-time curves acquired during the first pass of gadolinium contrast material were converted to the changes in relaxation rate to yield T2* relaxivity (Delta R2*) curve. The peak height of maximal signal intensity drop and the percentage of signal intensity recovery at the end of first pass were measured for each voxel in the PTL and CEL regions of the tumor.

RESULTS

The average peak height for the PTL was significantly higher (P=.04) in GBM than in MET. The average percentage of signal intensity recovery was significantly reduced in PTL (78.4% versus 82.8%; P=.02) and in CEL (62.5% versus 80.9%, P<.01) regions of MET compared with those regions in the GBM group.

CONCLUSIONS

The findings of our study show that the peak height and the percentage of signal intensity recovery derived from the Delta R2* curve of DSC perfusion MR imaging can differentiate GBM and MET.

Language barriers and resource utilization in a pediatric emergency department

BACKGROUND

Although an inability to speak English is recognized as an obstacle to health care in the United States, it is unclear how clinicians alter their diagnostic approach when confronted with a language barrier (LB).

OBJECTIVE

To determine if a LB between families and their emergency department (ED) physician was associated with a difference in diagnostic testing and length of stay in the ED.

DESIGN

Prospective cohort study.

METHODS

This study prospectively assessed clinical status and care provided to patients who presented to a pediatric ED from September 1997 through December 1997. Patients included were 2 months to 10 years of age, not chronically ill, and had a presenting temperature >/=38.5 degrees C or complained of vomiting, diarrhea, or decreased oral intake. Examining physicians determined study eligibility and recorded the Yale Observation Score if the patient was <3 years old, and whether there was a LB between the physician and the family. Standard hospital charges were applied for each visit to any of the 22 commonly ordered tests. Comparisons of total charges were made among groups using Mann-Whitney U tests. Analysis of covariance was used to evaluate predictors of total charges and length of ED stay.

RESULTS

Data were obtained about 2467 patients. A total of 286 families (12%) did not speak English, resulting in a LB for the physician in 209 cases (8.5%). LB patients were much more likely to be Hispanic (88% vs 49%), and less likely to be commercially insured (19% vs 30%). These patients were slightly younger (mean 31 months vs 36 months), but had similar acuity, triage vital signs, and Yale Observation Score (when applicable). In cases in which a LB existed, mean test charges were significantly higher: $145 versus $104, and ED stays were significantly longer: 165 minutes versus 137 minutes. In an analysis of covariance model including race/ethnicity, insurance status, physician training level, attending physician, urgent care setting, triage category, age, and vital signs, the presence of a LB accounted for a $38 increase in charges for testing and a 20 minute longer ED stay.

CONCLUSION

Despite controlling for multiple factors, the presence of a physician-family LB was associated with a higher rate of resource utilization for diagnostic studies and increased ED visit times. Additional study is recommended to explore the reasons for these differences and ways to provide care more efficiently to non-English-speaking patients.

Distinguishing recurrent intra-axial metastatic tumor from radiation necrosis following gamma knife radiosurgery using dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging

BACKGROUND AND PURPOSE

MR image-guided gamma knife radiosurgery is often used to treat intra-axial metastatic neoplasms. Following treatment, it is often difficult to determine whether a progressively enhancing lesion is due to metastatic tumor recurrence or radiation necrosis. The purpose of our study was to determine whether relative cerebral blood volume (rCBV), relative peak height (rPH), and percentage of signal-intensity recovery (PSR) derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging can distinguish recurrent metastatic tumor from radiation necrosis.

MATERIALS AND METHODS

Twenty-seven patients with systemic cancer underwent gamma knife radiosurgery for metastatic lesions of the brain and subsequently developed enlarging regions of enhancement within the radiation field. Subsequent surgical resection or clinicoradiologic follow-up established a diagnosis of recurrent metastatic tumor or radiation necrosis. Perfusion MR imaging datasets were retrospectively reprocessed, and regions of interest were drawn around the entire contrast-enhancing region. The resulting T2* signal-intensity time curves produced rCBV, rPH, and PSR values for each examination. A Welch t test was used to compare imaging values between groups.

RESULTS

The mean, minimum, and maximum PSR values were significantly lower (P < .01) in cases of recurrent metastatic tumor. The mean and maximum rCBV and rPH values were significantly higher (P < .02) in the recurrent metastatic tumor group.

CONCLUSIONS

The findings of our study suggest that perfusion MR imaging may be used to differentiate recurrent intra-axial metastatic tumor from gamma knife-induced radiation necrosis.

Diffusion-weighted MR imaging derived apparent diffusion coefficient is predictive of clinical outcome in primary central nervous system lymphoma

BACKGROUND AND PURPOSE

There is evidence that increased tumor cellular density within diagnostic specimens of primary central nervous system lymphoma (PCNSL) may have significant prognostic implications. Because cellular density may influence measurements of apparent diffusion coefficient (ADC) by using diffusion-weighted MR imaging (DWI), we hypothesized that ADC measured from contrast-enhancing regions might correlate with clinical outcome in patients with PCNSL.

MATERIALS AND METHODS

PCNSL tumors from 18 immunocompetent patients, treated uniformly with methotrexate-based chemotherapy, were studied with pretherapeutic DWI. Enhancing lesions were diagnosed by pathologic analysis as high-grade B-cell lymphomas. Regions of interest were placed around all enhancing lesions allowing calculation of mean, 25th percentile (ADC(25%)), and minimum ADC values. Histopathologic tumor cellularity was quantitatively measured in all patients. High and low ADC groups were stratified by the median ADC value of the cohort. The Welch t test assessed differences between groups. The Pearson correlation examined relationships between ADC measurements and tumor cellular density. Single and multivariable survival analysis was performed.

RESULTS

We detected significant intra- and intertumor heterogeneity in ADC measurements. An inverse correlation between cellular density and ADC measurements was observed (P < .05). ADC(25%) measurements less than the median value of 692 (low ADC group) were associated with significantly shorter progression-free and overall survival. Patients with improved clinical outcome were noted to exhibit a significant decrease in ADC measurements following high-dose methotrexate chemotherapy.

CONCLUSIONS

Our study provides evidence that ADC measurements within contrast-enhancing regions of PCNSL tumors may provide noninvasive insight into clinical outcome.

Locally advanced primary colorectal cancer: intraoperative electron and external beam irradiation +/- 5-FU

PURPOSE

For locally advanced primary colorectal cancer, our institution has combined intraoperative electron irradiation (IOERT) with external beam irradiation (EBRT) +/- 5-fluorouracil (5-FU) and surgical resection. Disease control and survival were compared with the current IOERT and prior non-IOERT regimens.

METHODS AND MATERIALS

From April 1981 through August 1995, 61 patients received an IOERT dose of 10-20 Gy, usually combined with 45-55 Gy of fractionated EBRT; 56 had minimum follow-up of 18 months. The amount of residual disease remaining at IOERT after exploration and maximal resection in the 56 patients was gross in 16, < or = microscopic in 39, and unresected in 1.

RESULTS

Survival (SR) and disease control were analyzed as a function of potential prognostic factors. Factors that achieved statistical significance for improved overall survival included treatment sequence of preop EBRT + 5-FU (vs. postoperative EBRT + 5-FU, p = 0.003) and < or = microscopic residual disease after maximal resection (vs. gross residual, p = 0.005). Those that appeared to favorably impact disease-free survival included EBRT + 5-FU (vs. EBRT alone, p = 0.01), < or = microscopic residual (vs. gross, p = 0.0014), and colon site of primary (vs. rectum, p = 0.009). Failures within an irradiation field have occurred in 4 of 16 patients (25%) who presented with gross residual after partial resection vs. 2 of 39 (5%) with < or = microscopic residual after gross total resection (p = 0.01). The significant prognostic factors for a decrease in distant metastases were the same as for disease-free SR with respective p-values of 0.013 (EBRT + 5-FU), 0.008 (microscopic residual), and 0.03 (colon primary). The current data suggests a relationship between IOERT dose and incidence of Grade 2 or 3 neuropathy (< or = 12.5 Gy--1 of 29 or 3%, > or = 15 Gy--6 of 26 or 23%, p = 0.03).

CONCLUSIONS

Both overall survival and disease control appear to be improved with the addition of IOERT to standard treatment. More routine use of systemic therapy is indicated as a component of IOERT containing treatment regimens because the incidence of distant metastases was 50% of patients at risk.

Imaging Characteristics of Pediatric Diffuse Midline Gliomas with Histone H3 K27M Mutation

BACKGROUND AND PURPOSE

The 2016 World Health Organization Classification of Tumors of the Central Nervous System includes "diffuse midline glioma with histone H3 K27M mutation" as a new diagnostic entity. We describe the MR imaging characteristics of this new tumor entity in pediatric patients.

MATERIALS AND METHODS

We retrospectively reviewed imaging features of pediatric patients with midline gliomas with or without the histone H3 K27 mutation. We evaluated the imaging features of these tumors on the basis of location, enhancement pattern, and necrosis.

RESULTS

Among 33 patients with diffuse midline gliomas, histone H3 K27M mutation was present in 24 patients (72.7%) and absent in 9 (27.3%). Of the tumors, 27.3% (n = 9) were located in the thalamus; 42.4% (n = 14), in the pons; 15% (n = 5), within the vermis/fourth ventricle; and 6% (n = 2), in the spinal cord. The radiographic features of diffuse midline gliomas with histone H3 K27M mutation were highly variable, ranging from expansile masses without enhancement or necrosis with large areas of surrounding infiltrative growth to peripherally enhancing masses with central necrosis with significant mass effect but little surrounding T2/FLAIR hyperintensity. When we compared diffuse midline gliomas on the basis of the presence or absence of histone H3 K27M mutation, there was no significant correlation between enhancement or border characteristics, infiltrative appearance, or presence of edema.

CONCLUSIONS

We describe, for the first time, the MR imaging features of pediatric diffuse midline gliomas with histone H3 K27M mutation. Similar to the heterogeneous histologic features among these tumors, they also have a diverse imaging appearance without distinguishing features from histone H3 wildtype diffuse gliomas.

A dual role for interferon-gamma in the pathogenesis of Sjogren's syndrome-like autoimmune exocrinopathy in the nonobese diabetic mouse

Sjogren's syndrome-like autoimmune exocrinopathy (AEC) in the nonobese diabetic (NOD) mouse progresses from a preimmune phase to an immune phase, resulting in dry mouth and/or dry eyes. In the present study, the impact of the prototypical T-helper type 1 cytokine, interferon-gamma (IFN-gamma), on the onset of AEC was investigated using both the IFN-gamma and the IFN-gamma receptor gene knockout mice, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-), respectively. Neither the NOD.IFN-gamma(-/-) nor the NOD.IFN-gammaR(-/-) mice exhibited increased acinar cell apoptosis and abnormal salivary protein expression, typically observed in parental NOD mice prior to disease. Without these preimmune phase abnormalities, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-) mice showed no subsequent autoimmune responses against the salivary glands at 20 weeks. Interestingly, real-time polymerase chain reaction and electrophoretic gel mobility shift assays suggested that IFN-gamma and STAT1, as well as the transcriptional activity of STAT1 in NOD glands, were increased at birth. Unlike the neonatal submandibular glands of NOD or NOD-scid mice that show abnormal glandular morphogenesis at birth, the submandibular glands of the newly constructed congenic strain, NOD-scid.IFN-gamma(-/-), were found to be normal. Taken together, IFN-gamma appears to play a critical role not only during the later immune phase of AEC, but also the early preimmune phase, independent of effector functions of immune cells. How exactly IFN-gamma functions during this period remains speculative.

Evidence for antimuscarinic acetylcholine receptor antibody-mediated secretory dysfunction in nod mice

OBJECTIVE

Antibodies directed against general and specific target-organ autoantigens are present in the sera of human patients and animal models with autoimmune disease. The relevance of these autoantibodies to the disease process remains ambiguous in most cases. In autoimmune exocrinopathy (Sjögren's syndrome), autoantibodies to the intracellular nuclear proteins SSA/Ro and SSB/La, as well as the cell surface muscarinic cholinergic receptor (M3) are observed. To evaluate the potential role of these factors in the loss of secretory function of exocrine tissues, a panel of monoclonal and polyclonal antibodies was developed for passive transfer into the NOD animal model.

METHODS

Monoclonal antibodies to mouse SSB/La, rat M3 receptor, and a rabbit polyclonal antiparotid secretory protein antibody were obtained for this study. These antibody reagents were subsequently infused into NOD-scid mice. Saliva flow rates were subsequently monitored over a 72-hour period. Submandibular gland lysates were examined by Western blotting for alteration of the distribution of the water channel protein aquaporin (AQP).

RESULTS

Evaluation of the secretory response indicated that only antibodies directed toward the extracellular domains of the M3 receptor were capable of mediating the exocrine dysfunction aspect of the clinical pathology of the autoimmune disease. In vitro stimulation with a muscarinic agonist of submandibular gland cells isolated from mice treated with anti-M3 antibody, but not saline or the isotype control, failed to translocate AQP to the plasma membrane.

CONCLUSION

These findings define a clear role for the humoral immune response and the targeting of the cell surface M3 signal transduction receptor as primary events in the development of clinical symptoms of autoimmune exocrinopathy. Furthermore, the anti-M3 receptor activity may negatively affect the secretory response through perturbation of normal signal transduction events, leading to translocation of the epithelial cell water channel.

Kinetic studies of thymidine phosphorylase from mouse liver

Initial velocity and product inhibition studies of thymidine phosphorylase from mouse liver revealed that the basic reaction mechanism of this enzyme is a rapid equilibrium random bi-bi mechanism with an enzyme-phosphate-thymine dead-end complex. Thymine displayed both substrate inhibition and nonlinear product inhibition, i.e., slope and intercept replots vs. 1/[thymine] were nonlinear, indicating that there is more than one binding site on the enzyme for thymine and that when thymine is bound to one of these sites, the enzyme is inhibited. Furthermore, both thymidine and phosphate showed "cooperative effects" in the presence of thymine at concentrations above 60 microM, suggesting that the enzyme may have multiple interacting allosteric and/or catalytic sites. The deoxyribosyl transferase reaction catalyzed by this enzyme is phosphate-dependent, requires nonstoichiometric amounts of phosphate, and can proceed by an "enzyme-bound" 2-deoxyribose 1-phosphate intermediate. These findings are in accord with the rapid equilibrium random bi-bi mechanism and demonstrate that deoxyribosyl transfer by this enzyme involves an indirect-transfer mechanism. These results strongly suggest that phosphorolysis and deoxyribosyl transfer are catalyzed by the same site on thymidine phosphorylase.

Structure-activity relationship of ligands of the pyrimidine nucleoside phosphorylases

Eighty-seven pyrimidine base and nucleoside analogs were evaluated as inhibitors of uridine phosphorylase (UrdPase) and thymidine phosphorylase (dThdPase). These findings, together with an extensive literature review, have allowed construction of structure-activity relationships for the binding of ligands to UrdPase and dThdPase and provide a basis for the rational design of new inhibitors of these enzymes. Additionally, 2,6-pyridinediol and 6-benzyl-2-thiouracil have been identified as being potent inhibitors of UrdPase and dThdPase respectively.

Intraoperative electron and external beam irradiation with or without 5-fluorouracil and maximum surgical resection for previously unirradiated, locally recurrent colorectal cancer

PURPOSE/OBJECTIVE

1) Disease control and survival will be evaluated for treatment regimens containing intraoperative electron irradiation (IOERT) for locally recurrent, previously unirradiated colorectal cancers. 2) Various prognostic factors will be evaluated to determine whether they have an impact on disease control or survival.

MATERIALS AND METHODS

From April 1981 through August 1995, 123 patients with previously unirradiated locally recurrent colorectal cancers received IOERT at our institution, usually as a supplement to external beam irradiation (EBRT) and maximum resection. All received EBRT with or without concomitant 5-fluorouracil-based chemotherapy. Forty-five Gy in 25 fractions was given to the tumor or tumor bed plus 3-cm to 5-cm margins in 121 of 123 patients and a boost of 5.4 to 9 Gy in 3 to 5 fractions to the tumor plus 2-cm margins. Maximum resection was performed before or after EBRT. IOERT doses ranged from 10 to 20 Gy in 119 of 123 patients, with dose dependent on resection margins (130 fields in 123 patients). Maintenance chemotherapy was given to only two patients.

RESULTS

Disease relapse and survival were evaluated. Central failure (within the IOERT field) was documented in 13 of 123 patients (11 percent) with a five-year actuarial rate of 26 percent. Local relapse (in EBRT field) occurred in 24 patients (20 percent); five-year rate was 37 percent. Distant metastases occurred in 66 patients (54 percent); five-year rate was 72 percent. Median survival was 28 months, with overall survival at two, three, and five years of 62, 39, and 20 percent, respectively. Tolerance data suggest a relationship between IOERT dose and incidence of Grade 2 or 3 neuropathy (< or = 12.5 Gy, 2 of 29 or 7 percent; > or = 15 Gy, 19 of 101 or 19 percent; P = 0.12). Survival and disease control were analyzed as a function of potential prognostic factors. None of the prognostic factors had a significant impact on disease control or survival. Although there was a trend for reduction in local relapse rates with gross total vs. partial resection, this neither achieved statistical significance nor translated into improved survival. Patients with gross residual disease after maximum resection had three-year and five-year survival rates of 36 and 18 percent, respectively, which paralleled results for patients with gross total resection at 41 and 24 percent, respectively.

CONCLUSION

Encouraging trends for improved local control with or without survival exist in separate locally recurrent colorectal IOERT analyses from our institution and other institutions. Therefore, continued evaluation of IOERT approaches seems warranted. Disease control within the IOERT and external fields is decreased when the surgeon is unable to accomplish a gross total resection. Therefore, it is reasonable to consistently add 5-fluorouracil or other dose modifiers during EBRT and to evaluate the use of dose modifiers in conjunction with IOERT (sensitizers and hyperthermia). In view of high systemic failure rates of > 50 percent in patients with locally recurrent disease, more routine use of systemic therapy is indicated as a component of IOERT-containing treatment regimens (use existent chemotherapy and/or develop effective immunotherapy and gene transfer therapy). Even with locally recurrent lesions, the aggressive multimodality approaches including IOERT have resulted in improved local control and long-term survival rates of 20 percent vs. an expected 5 percent with conventional techniques.

Progress in understanding autoimmune exocrinopathy using the non-obese diabetic mouse: an update

Sjögren's Syndrome (SS) is a chronic autoimmune disease characterized by histological and functional alterations of salivary and lacrimal glands that result in a severe dryness of the mouth and the eyes. The etiology of SS has remained undefined despite investigators' significant efforts to identify the mechanisms of initiation. Based on histopathology, several animal models are available--such as MRL/lpr, NZW/NZB, NFS/sld, graft vs. host, transgenic mouse expressing viral surface antigen, and the non-obese diabetic (NOD) mouse--for investigation of the etiology of SS. Biochemical and immunological similarities between human SS and autoimmune exocrinopathy (AEC) in the NOD mouse, including the loss of secretory function, establish the NOD mouse as an appropriate model to unravel the underlying pathophysiology of SS. Recently, several NOD congenic partner strains have been developed to investigate the roles of genetic intervals, cytokines, and autoantibodies in the disease pathogenesis. Studies on NOD-scid suggest that the pathogenesis of SS occurs in two phases: an asymptomatic phase, in which epithelial cells of exocrine tissues undergo dedifferentiation accompanied by elevated apoptosis; and a second phase in which autoaggression is mounted against target organ autoantigens, resulting in the activation of T- and B-cells, and the generation of autoantibodies. The presence of autoantibodies on the cell-surface signaling receptor, the muscarinic(3) receptor, in both SS patients and the NOD mice correlates with the hallmark clinical symptom of secretory dysfunction. Additionally, the NOD mouse model provides an important example of how both Th1 and Th2 cytokines, as well as non-immune genetic loci, are involved in the maintenance of and progression to the overt disease state. Ultimately, analysis of these data provides insight into potentially novel therapeutic interventions.

5-benzylacyclouridine and 5-benzyloxybenzylacyclouridine, potent inhibitors of uridine phosphorylase

Various pyrimidine acyclonucleosides (1-(2'-hydroxyethoxymethyl)uracils) are specific inhibitors of uridine phosphorylase[Niedzwicki et al., Biochem. Pharmac. 30, 2097 (1981) )). 5-Benzyluracils have also been shown to inhibit this enzyme[Baker and Kelley, J. med. Chem. 13, 461 (1970); Woodman et al., Biochem. Pharmac. 29, 1059 (1980) )). We have synthesized the acyclonucleoside analogs of 5-benzyluracil (BU) and 5-benzyloxybenzyluracil (BBU). These compounds, 5-benzyl-1-(2'-hydroxyethoxymethyl)uracil (BAU) and 5-(m-benzyloxybenzyl)-1-(2'-hydroxyethoxymethyl)uracil (BBAU), are potent inhibitors of uridine phosphorylase. K1 values of 98 and 32 nM were estimated for BAU and BBAU respectively. These compounds are better inhibitors of uridine phosphorylase than BU (K1= 1575 nM), BBU (K1=270 nM), and all other compounds previously tested, and they have no effect on thymidine phosphorylase, uridine-cytidine kinase, or thymidine kinase. Potential chemotherapeutic applications of BAU and BBAU are discussed.

Incremental costs of enrolling cancer patients in clinical trials: a population-based study

BACKGROUND

Payment for care provided as part of clinical research has become less predictable as a result of managed care. Because little is known at present about how entry into cancer trials affects the cost of care for cancer patients, we conducted a matched case-control comparison of the incremental medical costs attributable to participation in cancer treatment trials.

METHODS

Case patients were residents of Olmsted County, MN, who entered phase II or phase III cancer treatment trials at the Mayo Clinic from 1988 through 1994. Control patients were patients who did not enter trials but who were eligible on the basis of tumor registry matching and medical record review. Sixty-one matched pairs were followed for up to 5 years after the date of trial entry for case patients or from an equivalent date for control patients. Hospital, physician, and ancillary service costs were estimated from a population-based cost database developed at the Mayo Clinic.

RESULTS

Trial enrollees incurred modestly (no more than 10%) higher costs over various follow-up periods. The mean cumulative 5-year cost in 1995 inflation-adjusted U.S. dollars among trial enrollees after adjustment for censoring was $46424 compared with $44 133 for control patients. After 1 year, trial enrollee costs were $24645 compared with $23 964 for control patients.

CONCLUSIONS

This study suggests that cancer chemotherapy trials may not imply budget-breaking costs. Cancer itself is a high-cost illness. Clinical protocols may add relatively little to that cost.

IL-4-dependent effector phase in autoimmune exocrinopathy as defined by the NOD.IL-4-gene knockout mouse model of Sjögren's syndrome

NOD mice manifest many features of autoimmune exocrinopathy (Sjögren's syndrome), a disease generally characterized by a chronic, progressive immunological attack against the exocrine tissues of the salivary and lacrimal glands. Previous studies using the NOD congenic partner strain, NOD.Igmu(null), defined an important role for B lymphocytes in the development of xerostomia, implicating autoantibodies reactive with the acetylcholine muscarinic receptor (M3R) as the possible effector mechanism. In the present study, we have examined the impact of the cytokine, interleukin (IL)-4, on autoimmune exocrinopathy by using the IL-4 gene knockout (KO) NOD mouse strain, NOD.IL-4-/-. Despite manifesting the physiological aberrations and marked leukocytic infiltration of the salivary glands characteristic of autoimmune xerostomia in NOD mice, the NOD.IL-4-/- mice do not develop xerostomia. However, NOD.IL-4-/- mice that received adoptively transferred T lymphocytes derived from NOD.Igmu-/- mice progress to xerostomia, thereby reversing the defect. While progression or lack of progression to xerostomia correlated with the ability of the NOD.IL-4-/- mice to express detectable anti-M3R autoantibodies, the precise mechanism of how IL-4 influences the development of autoimmune xerostomia remains speculative.

Activation-induced cell death of rat astrocytes

Inflammatory activation of astrocytes has been implicated in various neurodegenerative diseases. The elimination of activated astrocytes by apoptosis or the deactivation may be the mechanisms for auto-regulation of activated astrocytes. To test the possibility of apoptotic elimination of activated astrocytes, we examined a potential correlation between activation state of astrocytes and their viability using C6 rat glial cells and rat primary astrocyte cultures exposed to a variety of inflammatory stimuli such as lipopolysaccharide, interferon-gamma, and tumor necrosis factor-alpha. Nitric oxide production was measured to evaluate inflammatory activation of astrocytes. We found that: (i) the activation of astrocytes by the combination of lipopolysaccharide and inflammatory cytokines, but not by either alone, led to nitric oxide production followed by apoptotic cell death; (ii) the amount of nitric oxide produced by activated astrocytes was inversely proportional to the viability of the cells; (iii) inhibition of nitric oxide synthase by N-monomethyl L-arginine blocked death of activated astrocytes; and (iv) nitric oxide donors induced apoptosis of astrocytes in a caspase-dependent manner. Taken collectively, our results suggest that activated astrocytes produce nitric oxide as an autocrine mediator of caspase-dependent apoptosis, and this type of programmed cell death of astrocytes may be the underlying mechanism for the auto-regulation of inflammatory activation of astrocytes.

Spectroscopic magnetic resonance imaging of a tumefactive demyelinating lesion

Tumefactive demyelinating lesions can present with features similar, clinically and radiologically, to those of brain tumours. Proton MR spectroscopy has been increasingly used to characterize intracranial pathology. As the underlying pathophysiology of neoplasms is different from that of demyelinating disease, one may expect the metabolic composition of neoplasms to be significantly different from that of demyelinating lesions. We report a 49-year-old woman in whom the neurologic and radiologic findings were highly suggestive of a high-grade brain tumor, and the spectroscopic features were sufficiently similar to that of a tumor to convince the neurosurgeon to operate. This case emphasizes the need for caution when confronted with a patient who presents with a differential diagnosis of demyelinating lesion versus neoplasm.