Multinational External Validation of Autonomous Retinopathy of Prematurity Screening.

Importance: Retinopathy of prematurity (ROP) is a leading cause of blindness in children, with significant disparities in outcomes between high-income and low-income countries, due in part to insufficient access to ROP screening. Objective: To evaluate how well autonomous artificial intelligence (AI)-based ROP screening can detect more-than-mild ROP (mtmROP) and type 1 ROP. Design, Setting, and Participants: This diagnostic study evaluated the performance of an AI algorithm, trained and calibrated using 2530 examinations from 843 infants in the Imaging and Informatics in Retinopathy of Prematurity (i-ROP) study, on 2 external datasets (6245 examinations from 1545 infants in the Stanford University Network for Diagnosis of ROP [SUNDROP] and 5635 examinations from 2699 infants in the Aravind Eye Care Systems [AECS] telemedicine programs). Data were taken from 11 and 48 neonatal care units in the US and India, respectively. Data were collected from January 2012 to July 2021, and data were analyzed from July to December 2023. Exposures: An imaging processing pipeline was created using deep learning to autonomously identify mtmROP and type 1 ROP in eye examinations performed via telemedicine. Main Outcomes and Measures: The area under the receiver operating characteristics curve (AUROC) as well as sensitivity and specificity for detection of mtmROP and type 1 ROP at the eye examination and patient levels. Results: The prevalence of mtmROP and type 1 ROP were 5.9% (91 of 1545) and 1.2% (18 of 1545), respectively, in the SUNDROP dataset and 6.2% (168 of 2699) and 2.5% (68 of 2699) in the AECS dataset. Examination-level AUROCs for mtmROP and type 1 ROP were 0.896 and 0.985, respectively, in the SUNDROP dataset and 0.920 and 0.982 in the AECS dataset. At the cross-sectional examination level, mtmROP detection had high sensitivity (SUNDROP: mtmROP, 83.5%; 95% CI, 76.6-87.7; type 1 ROP, 82.2%; 95% CI, 81.2-83.1; AECS: mtmROP, 80.8%; 95% CI, 76.2-84.9; type 1 ROP, 87.8%; 95% CI, 86.8-88.7). At the patient level, all infants who developed type 1 ROP screened positive (SUNDROP: 100%; 95% CI, 81.4-100; AECS: 100%; 95% CI, 94.7-100) prior to diagnosis. Conclusions and Relevance: Where and when ROP telemedicine programs can be implemented, autonomous ROP screening may be an effective force multiplier for secondary prevention of ROP.

External Validation of a Retinopathy of Prematurity Screening Model Using Artificial Intelligence in 3 Low- and Middle-Income Populations.

Importance: Retinopathy of prematurity (ROP) is a leading cause of preventable blindness that disproportionately affects children born in low- and middle-income countries (LMICs). In-person and telemedical screening examinations can reduce this risk but are challenging to implement in LMICs owing to the multitude of at-risk infants and lack of trained ophthalmologists. Objective: To implement an ROP risk model using retinal images from a single baseline examination to identify infants who will develop treatment-requiring (TR)-ROP in LMIC telemedicine programs. Design, Setting, and Participants: In this diagnostic study conducted from February 1, 2019, to June 30, 2021, retinal fundus images were collected from infants as part of an Indian ROP telemedicine screening program. An artificial intelligence (AI)-derived vascular severity score (VSS) was obtained from images from the first examination after 30 weeks' postmenstrual age. Using 5-fold cross-validation, logistic regression models were trained on 2 variables (gestational age and VSS) for prediction of TR-ROP. The model was externally validated on test data sets from India, Nepal, and Mongolia. Data were analyzed from October 20, 2021, to April 20, 2022. Main Outcomes and Measures: Primary outcome measures included sensitivity, specificity, positive predictive value, and negative predictive value for predictions of future occurrences of TR-ROP; the number of weeks before clinical diagnosis when a prediction was made; and the potential reduction in number of examinations required. Results: A total of 3760 infants (median [IQR] postmenstrual age, 37 [5] weeks; 1950 male infants [51.9%]) were included in the study. The diagnostic model had a sensitivity and specificity, respectively, for each of the data sets as follows: India, 100.0% (95% CI, 87.2%-100.0%) and 63.3% (95% CI, 59.7%-66.8%); Nepal, 100.0% (95% CI, 54.1%-100.0%) and 77.8% (95% CI, 72.9%-82.2%); and Mongolia, 100.0% (95% CI, 93.3%-100.0%) and 45.8% (95% CI, 39.7%-52.1%). With the AI model, infants with TR-ROP were identified a median (IQR) of 2.0 (0-11) weeks before TR-ROP diagnosis in India, 0.5 (0-2.0) weeks before TR-ROP diagnosis in Nepal, and 0 (0-5.0) weeks before TR-ROP diagnosis in Mongolia. If low-risk infants were never screened again, the population could be effectively screened with 45.0% (India, 664/1476), 38.4% (Nepal, 151/393), and 51.3% (Mongolia, 266/519) fewer examinations required. Conclusions and Relevance: Results of this diagnostic study suggest that there were 2 advantages to implementation of this risk model: (1) the number of examinations for low-risk infants could be reduced without missing cases of TR-ROP, and (2) high-risk infants could be identified and closely monitored before development of TR-ROP.

MicroRNA-124 expression counteracts pro-survival stress responses in glioblastoma.

Glioblastomas are aggressive adult brain tumors, characterized by inadequately organized vasculature and consequent nutrient and oxygen (O2)-depleted areas. Adaptation to low nutrients and hypoxia supports glioblastoma cell survival, progression and therapeutic resistance. However, specific mechanisms promoting cellular survival under nutrient and O2 deprivation remain incompletely understood. Here, we show that miR-124 expression is negatively correlated with a hypoxic gene signature in glioblastoma patient samples, suggesting that low miR-124 levels contribute to pro-survival adaptive pathways in this disease. As miR-124 expression is repressed in various cancer types (including glioblastoma), we quantified miR-124 abundance in normoxic and hypoxic regions in glioblastoma patient tissue, and investigated whether ectopic miR-124 expression compromises cell survival during tumor ischemia. Our results indicate that miR-124 levels are further diminished in hypoxic/ischemic regions within individual glioblastoma patient samples, compared with regions replete in O2 and nutrients. Importantly, we also show that increased miR-124 expression affects the ability of tumor cells to survive under O2 and/or nutrient deprivation. Moreover, miR-124 re-expression increases cell death in vivo and enhances the survival of mice bearing intracranial xenograft tumors. miR-124 exerts this phenotype in part by directly regulating TEAD1, MAPK14/p38α and SERP1, factors involved in cell proliferation and survival under stress. Simultaneous suppression of these miR-124 targets results in similar levels of cell death as caused by miR-124 restoration. Importantly, we further demonstrate that SERP1 reintroduction reverses the hypoxic cell death elicited by miR-124, indicating the importance of SERP1 in promoting tumor cell survival. In support of our experimental data, we observed a significant correlation between high SERP1 levels and poor patient outcome in glioblastoma patients. Collectively, among the many pro-tumorigeneic properties of miR-124 repression in glioblastoma, we delineated a novel role in promoting tumor cell survival under stressful microenvironments, thereby supporting tumor progression.

Stereotactic body radiation therapy for gastrointestinal malignancies.

Stereotactic body radiotherapy (SBRT) is an emerging treatment for pancreas cancer and liver tumors. Early data suggest excellent control rates for locally advanced pancreas cancer. However, due to the close proximity of the duodenum and stomach, steps to effectively minimize toxicities must be taken through image guidance of treatments. SBRT for liver tumors has also shown high rates of local control with low risks for hepatic toxicity. Careful selection of cases for SBRT is essential to achieve disease control and to minimize toxicity for patients. In treatment, attention must be paid to minimizing exposure of nearby normal tissues, including ribs, skin and bowel as well as the functioning organs surrounding the tumors. There is no accepted standard for the SBRT dose/fractionation schedule for these cases and the optimal strategy will likely depend on the size, number and location of lesions for each patient. However, the published data seem to suggest an overall dose-response effect. To realize the clinical potential of SBRT for these tumors, investigations are needed to determine optimum fractionation schedules and to integrate its use with systemic chemotherapy programs.

Early treatment failure in intermediate-risk rhabdomyosarcoma: results from IRS-IV and D9803--a report from the Children's Oncology Group.

PURPOSE: The goal of this study was to determine the frequency and clinical features of early treatment failure during induction chemotherapy before protocol radiation therapy for children with intermediate-risk rhabdomyosarcoma (RMS). PATIENTS AND METHODS: Patients with intermediate-risk RMS enrolled onto the Intergroup Rhabdomyosarcoma Study-IV and the Children's Oncology Group D9803 study were reviewed for an early treatment failure. Early failure was defined as failure caused by progressive disease, death as a result of progressive disease, or death as a result of other causes occurring fewer than 120 days from study entry. Patients with parameningeal site RMS with high-risk features who received radiation therapy at week 1 were excluded from analysis. Overall survival (OS) was estimated using the Kaplan-Meier method. Fisher's exact test was used to compare differences between groups. Cumulative incidence of progression was estimated. RESULTS: Of 916 patients, 20 (2.2%) were found to have an early disease progression and did not receive planned protocol radiotherapy. Three additional early failures resulted from treatment-related death without progression. Median time to failure was 48 days (range, 7 to 106 days). Nineteen (95%) of the 20 patients experienced progression at their primary site. Five-year OS was 32% (95% CI, 12% to 54%) for patients experiencing an early progression. CONCLUSION: A small proportion of patients with intermediate-risk RMS suffer an early failure as a result of early progression (2.2%) or treatment-related mortality (0.3%). The majority of patients with early progression had a local failure. Earlier radiotherapy could potentially improve outcome by preventing early local progression.

Comparison of intensity-modulated radiotherapy and 3-dimensional conformal radiotherapy as adjuvant therapy for gastric cancer.

BACKGROUND: The current study was performed to compare the clinical outcomes and toxicity in patients treated with postoperative chemoradiotherapy for gastric cancer using intensity-modulated radiotherapy (IMRT) versus 3-dimensional conformal radiotherapy (3D CRT). METHODS: Fifty-seven patients with gastric or gastroesophageal junction cancer were treated postoperatively: 26 with 3D CRT and 31 with IMRT. Concurrent chemotherapy was capecitabine (n=31), 5-fluorouracil (5-FU) (n=25), or none (n=1). The median radiation dose was 45 Gy. Dose volume histogram parameters for kidney and liver were compared between treatment groups. RESULTS: The 2-year overall survival rates for 3D CRT versus IMRT were 51% and 65%, respectively (P=.5). Four locoregional failures occurred each in the 3D CRT (15%) and the IMRT (13%) patients. Grade>or=2 acute gastrointestinal toxicity was found to be similar between the 3D CRT and IMRT patients (61.5% vs 61.2%, respectively) but more treatment breaks were needed (3 vs 0, respectively). The median serum creatinine from before radiotherapy to most recent creatinine was unchanged in the IMRT group (0.80 mg/dL) but increased in the 3D CRT group from 0.80 mg/dL to 1.0 mg/dL (P=.02). The median kidney mean dose was higher in the IMRT versus the 3D CRT group (13.9 Gy vs 11.1 Gy; P=.05). The median kidney V20 was lower for the IMRT versus the 3D CRT group (17.5% vs 22%; P=.17). The median liver mean dose for IMRT and 3D CRT was 13.6 Gy and 18.6 Gy, respectively (P=.19). The median liver V30 was 16.1% and 28%, respectively (P<.001). CONCLUSIONS: Adjuvant chemoradiotherapy was well tolerated. IMRT was found to provide sparing to the liver and possibly renal function.

Stereotactic radiosurgery for treatment of spinal metastases recurring in close proximity to previously irradiated spinal cord.

PURPOSE: As the spinal cord tolerance often precludes reirradiation with conventional techniques, local recurrence within a previously irradiated field presents a treatment challenge. METHODS AND MATERIALS: We retrospectively reviewed 51 lesions in 42 patients treated from 2002 to 2008 whose spinal metastases recurred in a previous radiation field (median previous spinal cord dose of 40 Gy) and were subsequently treated with stereotactic radiosurgery (SRS). RESULTS: SRS was delivered to a median marginal dose of 20 Gy (range, 10-30 Gy) in 1-5 fractions (median, 2), targeting a median tumor volume of 10.3 cm(3) (range, 0.2-128.6 cm(3)). Converting the SRS regimens with the linear quadratic model (α/ß = 3), the median spinal cord maximum single-session equivalent dose (SSED) was 12.1 Gy(3) (range, 4.7-19.3 Gy(3)). With a median follow-up of 7 months (range, 2-47 months), the Kaplan-Meier local control and overall survival rates at 6/12 months were 87%/73% and 81%/68%, respectively. A time to retreatment of ≤12 months and the combination of time to retreatment of ≤12 months with an SSED of <15 Gy(10) were significant predictors of local failure on univariate and multivariate analyses. In patients with a retreatment interval of <12 months, 6/12 month local control rates were 88%/58%, with a SSED of >15 Gy(10), compared to 45%/0% with <15 Gy(10), respectively. One patient (2%) experienced Grade 4 neurotoxicity. CONCLUSION: SRS is safe and effective in the treatment of spinal metastases recurring in previously irradiated fields. Tumor recurrence within 12 months may correlate with biologic aggressiveness and require higher SRS doses (SSED >15 Gy(10)). Further research is needed to define the partial volume retreatment tolerance of the spinal cord and the optimal target dose.

18Fluorodeoxyglucose PET is prognostic of progression-free and overall survival in locally advanced pancreas cancer treated with stereotactic radiotherapy.

PURPOSE: This study analyzed the prognostic value of positron emission tomography (PET) for locally advanced pancreas cancer patients undergoing stereotactic body radiotherapy (SBRT). PATIENTS AND METHODS: Fifty-five previously untreated, unresectable pancreas cancer patients received a single fraction of 25-Gy SBRT sequentially with gemcitabine-based chemotherapy. On the preradiation PET-CT, the tumor was contoured and the maximum standardized uptake value (SUVmax) and metabolic tumor burden (MTB) were calculated using an in-house software application. High-SUVmax and low-SUVmax subgroups were created by categorizing patients above or below the median SUVmax. The analysis was repeated to form high-MTB and low-MTB subgroups as well as clinically relevant subgroups with SUVmax values of <5, 5-10, or >10. Multivariate analysis analyzing SUVmax, MTB, age, chemotherapy cycles, and pretreatment carbohydrate antigen (CA)19-9 was performed. RESULTS: For the entire population, median survival was 12.7 months. Median survival was 9.8 vs.15.3 months for the high- and low- SUVmax subgroups (p <0.01). Similarly, median survival was 10.1 vs. 18.0 months for the high MTB and low MTB subgroups (p <0.01). When clinical SUVmax cutoffs were used, median survival was 6.4 months in those with SUVmax >10, 9.5 months with SUVmax 5.0-10.0, and 17.7 months in those with SUVmax <5 (p <0.01). On multivariate analysis, clinical SUVmax was an independent predictor for overall survival (p = 0.03) and progression-free survival (p = 0.03). CONCLUSION: PET scan parameters can predict for length of survival in locally advanced pancreas cancer patients.

Multimodality treatment with intensity modulated radiation therapy for esophageal cancer.

The objective of this study is to determine the feasibility and report the outcome of patients with locally advanced esophageal cancer treated with preoperative or definitive chemoradiotherapy (CRT) using intensity-modulated radiation therapy (IMRT). Between 2003 and 2007, 30 patients with non-cervical esophageal cancer received concurrent chemotherapy and IMRT at Stanford University. Eighteen patients were planned for definitive CRT and 12 were planned for preoperative CRT. All patients had computed tomography-based treatment planning and received IMRT. The median dose delivered was 50.4 Gy. Patients planned for preoperative CRT underwent surgery 4-13 weeks (median 8.3 weeks) following completion of CRT. Median follow-up of surviving patients from start of RT was 24.2 months (range 8.2-38.3 months). The majority of tumors were adenocarcinomas (67%) and poorly differentiated (57%). Tumor location was 7% upper, 20% mid, 47% lower, and 27% gastroesophageal junction. Actuarial 2-year local-regional control (LRC) was 64%. High tumor grade was an adverse prognostic factor for LRC and overall survival (OS) (P= 0.015 and 0.012, respectively). The 2-year LRC was 83% vs. 51% for patients treated preoperatively vs. definitively (P= 0.32). The 2-year disease-free and OS were 38% and 56%, respectively. Twelve patients (40%) required feeding tube placement, and the average weight loss from baseline was 4.8%. Twelve (40%) patients experienced grade 3+ acute complications and one patient died of complications following feeding tube placement. Three patients (10%) required a treatment break. Eight patients (27%) experienced grade 3 late complications. No grade 4 complications were seen. IMRT was effective and well tolerated. Disease recurrence remains a challenge and further investigation with dose escalation to improve LRC and OS is warranted.

Interfractional uncertainty in the treatment of pancreatic cancer with radiation.

PURPOSE: To compare the interfractional variation in pancreatic tumor position using bony anatomy and implanted fiducial markers. METHODS AND MATERIALS: Five consecutively treated patients with pancreatic adenocarcinoma who received definitive intensity-modulated radiation therapy at Stanford University (Stanford, CA) underwent fiducial seed placement and treatment on the Varian Trilogy system (Varian, Palo Alto, CA) with respiratory gating. Daily orthogonal kilovoltage imaging was performed to verify patient positioning, and isocenter shifts were made initially to match bony anatomy. Next, a final shift to the fiducial seeds was made under fluoroscopic guidance to confirm the location of the pancreatic tumor during the respiratory gated phase. All shifts were measured along three axes, left (+)-right (-), anterior (-)-posterior (+), and superior (+)-inferior (-), and the overall interfractional tumor movement was calculated based on these values. RESULTS: A total of 140 fractions were analyzed. The mean absolute shift to fiducial markers after shifting to bony anatomy was 1.6 mm (95th percentile, 7 mm; range, 0-9 mm), 1.8 mm (95th percentile, 7 mm; range, 0-13 mm), and 4.1 mm (95th percentile, 12 mm; range, 0-19 mm) in the anterior-posterior, left-right, and superior-inferior directions, respectively. The mean interfractional vector shift distance was 5.5 mm (95th percentile, 14.5 mm; range, 0-19.3 mm). In 28 of 140 fractions (20%) no fiducial shift was required after alignment to bony anatomy. CONCLUSIONS: There is substantial residual uncertainty after alignment to bony anatomy when radiating pancreatic tumors using respiratory gating. Bony anatomy matched tumor position in only 20% of the radiation treatments. If bony alignment is used in conjunction with respiratory gating without implanted fiducials, treatment margins need to account for this uncertainty.

Pancreatic tumor motion on a single planning 4D-CT does not correlate with intrafraction tumor motion during treatment.

PURPOSE: To quantify pancreas tumor motion on both a planning 4D-CT and during a single fraction treatment using the CyberKnife linear accelerator and Synchrony respiratory tracking software, and to investigate whether a single 4D-CT study is reliable for determining radiation treatment margins for patients with locally advanced pancreas cancer. METHODS AND MATERIALS: Twenty patients underwent fiducial placement, biphasic pancreatic protocol CT scan and 4D-CT scan in the treatment position while free-breathing. Patients were then treated with a single 25 Gy fraction of stereotactic body radiotherapy. Predicted pancreas motion in the superior-inferior (SI), left-right (LR), and anterior-posterior (AP) directions was calculated from the maximum inspiration and maximum expiration 4D-CT scan. For CyberKnife treatments, mean respiratory cycle motion and maximum respiratory cycle motion was determined in the SI, LR, and AP directions. RESULTS: The range of centroid movement based on 4D-CT in the SI, LR, and AP directions were 0.9 to 28.8 mm, 0.1 to 13.7 mm, and 0.2 to 7.6 mm, respectively. During CyberKnife treatment, in the SI direction, the mean motion of the centroid ranged from 0.5 to 12.7 mm. In the LR direction, the mean motion range was 0.4 to 9.4 mm. In the AP direction, the mean motion range was 0.6 to 5.5 mm. The maximum range of movement (mean) during CyberKnife treatment in the SI, LR, and AP directions were 4.5 to 48.8 mm (mean 20.8 mm), 1.5 to 41.3 mm (mean 11.3 mm), and 1.6 to 68.1 mm (mean 13.4 mm), respectively. Neither the maximum or mean motion correlated with the 4D-CT movement. CONCLUSIONS: There is substantial respiratory associated motion of pancreatic tumors. The 4D-CT planning scans cannot accurately predict the movement of pancreatic tumors during actual treatment on CyberKnife.

A syndrome of irreversible leukoencephalopathy following pediatric allogeneic bone marrow transplantation.

BACKGROUND: Despite decreases in overall mortality following bone marrow transplantation (BMT), a number of complications such as neurotoxicity have been described and often associated with immunosuppressive agents. The syndrome of reversible posterior leukoencephalopathy has been described in patients receiving cyclosporin and FK-506. We report here a subset of children who developed a syndrome of previously undescribed irreversible leukoencephalopathy following allogeneic BMT. PATIENTS AND METHODS: Between 1996 and 2002, 138 pediatric patients received an allogeneic BMT at Lucile Salter Packard Children's Hospital at Stanford. Six cases of irreversible leukoencephalopathy were observed. Cases were defined as children who exhibited progressive and continued, severe neurologic deterioration lasting greater than 2 weeks and consistent with non-localizing, central nervous system abnormalities. Medical records and magnetic resonance images (MRIs) were reviewed. RESULTS: Median age of the affected patients at BMT was 7.8 years. All six received cyclosporine, and [corrected] one had elevated drug levels. Encephalopathy occurred at a median of 53 days (range 14-77) following BMT. Symptoms at onset of leukoenceophalopathy included confusion and altered mental status, sluggish pupillary responses, abnormal movements, and seizures. Two patients died during their neurologic decline. Four patients remain alive with persistent encephalopathy. MRI showed abnormalities in all patients including periventricular or subcortical white matter involvement in all, and basal ganglia lesions in three. CONCLUSIONS: We report a syndrome of irreversible neurologic deficits and cerebral white matter abnormalities following allogeneic BMT, yet not associated with elevated cyclosporin levels. A precise mechanism for this syndrome is lacking and warrants further consideration.

Induction of UGT1A6 isoform by inflammatory conditions in rat astrocytes.

Alteration of drug metabolism under diseased conditions is of clinical importance. We have investigated the effects of inflammatory conditions on phase II drug-metabolizing enzyme activity in rat cultured astrocytes. Lipopolysaccharide (LPS) treatment was used to promote inflammatory conditions. Thus, we reported that LPS initiates an inflammatory response, which is mediated by pro-inflammatory mediators and free radical generation. An increase in astrocyte glucuronidation activity was observed after a 48-h LPS treatment. This increase in glucuronidation activity was associated with an up-regulation of the UGT1A6 isoform mRNA level as shown by RT-PCR and gene reporter assay. Moreover, this endotoxin-induced increase in UGT1A6 expression level was blocked by actinomycin D and cycloheximide, indicating the requirement for RNA and protein synthesis. The UGT1A6 expression enhancement could be prevented by anti-inflammatory drugs (dexamethasone and NS398) or nitric oxide synthase inhibitors (L-NAME and L-NMMA). Moreover, gel shift assay revealed increased activator protein-1 (AP-1) binding activity after LPS treatment. We propose, based on the data presented, that the action of LPS to induce UGT1A6 isoform up-regulation may be mediated by pro-inflammatory mediator accumulation, and AP-1 binding activity increase.

Identifying site-specific metastasis genes and functions.

Metastasis is a multistep and multifunctional biological cascade that is the final and most life-threatening stage of cancer progression. Understanding the biological underpinnings of this complex process is of extreme clinical relevance and requires unbiased and comprehensive biological scrutiny. In recent years, we have utilized a xenograft model of breast cancer metastasis to discover genes that mediate organ-specific patterns of metastatic colonization. Examination of transcriptomic data from cohorts of primary breast cancers revealed a subset of site-specific metastasis genes that are selected for early in tumor progression. High expression of these genes predicts the propensity for lung metastasis independently of several classic markers of poor prognosis. These genes fulfill dual functions-enhanced primary tumorigenicity and augmented organ-specific metastatic activity. Other metastasis genes fulfill functions specialized for the microenvironment of the metastatic site and are consequently not selected for in primary tumors. These findings improve our understanding of metastatic progression, facilitate the interpretation of primary tumor gene expression data, and open several important possibilities for future clinical application.

Redox state alteration modulates astrocyte glucuronidation.

We have investigated the effects of mild oxidative conditions on drug-metabolizing enzyme activity in rat cultured astrocytes. These experimental conditions promoting an oxidative environment were obtained by short exposure to a low concentration of menadione (5 microM) for a short duration (15 min). This resulted in the rapid and transient production of reactive oxygen species (+130%), associated with a decrease in GSH cellular content (-24%), and an increase in total protein oxidation (+26%), but promoted neither PGE(2) nor NO production. This treatment induced a rapid and persistent decrease in astrocyte glucuronidation activities, which was totally prevented by N-acetyl-l-cysteine. These oxidative conditions also affected the specific UGT1A6 activity measured in transfected V79-1A6 cells. Finally, the subsequent recovery of astrocyte glucuronidation activity may result from upregulation of UGT1A6 expression (+62%) as shown by RT-PCR and gene reporter assay. These results show that the catalytic properties and expression of cerebral UGT1A6 are highly sensitive to the redox environment. The protective effect of N-acetyl-l-cysteine suggests both a direct action of reactive oxygen species on the protein and a more delayed action on the transcriptional regulation of UGT1A6. These results suggest that cerebral metabolism can be altered by physiological or pathological redox modifications.

Activation of peroxisome proliferator-activated receptor alpha in rat spinal cord after peripheral noxious stimulation.

Following recurrent noxious stimulation, both functional modification and structural reorganization such as activation of the arachidonate cascade or axon sprouting occur in the central nervous system (CNS). It has been recently proposed that these alterations observed during chronic pain state were supported by an intensification of the lipid metabolism. In this regard, it has been shown that mRNA coding for several fatty acid metabolizing enzymes are up-regulated in the rat lumbar spinal cord in response to persistent nociception induced by a peripheral inflammation. As peroxisome proliferators-activated receptor (PPAR) could mediate such effects, we therefore investigated the activation of this transcription factor in the rat spinal cord following subcutaneous injection of complete Freund's adjuvant (CFA) into a hind paw. In this study, we compared the DNA-binding activity of nuclear proteins extracted from healthy and inflamed rats toward a PPAR response element. Using electrophoretic mobility-shift assay (EMSA), we found that only the PPARalpha isoform was activated in the rat spinal cord after CFA injection. This activation occurred rapidly, as early as 30 min post-CFA injection, and was persistent up to 10 h, reaching a maximum at 6h after CFA injection. In view of the consequences of PPARalpha activation in other tissues, these results suggest that fatty acid utilization is enhanced in the CNS during chronic pain state. Although the physiopathological relevance of PPARalpha activation during hyperalgesia needs further investigation, we provided here a new player in the molecular modeling of pain pathways.

Up-regulation of fatty acid metabolizing-enzymes mRNA in rat spinal cord during persistent peripheral local inflammation.

Persistent peripheral inflammation is associated with repetitive painful inputs into the spinal cord, leading to a chronic pain state. Related dramatic changes occur in the central nervous system (CNS) including central sensitization, which results in hyperalgesia. This neural plasticity involves in part fatty acids as functional and structural compounds. We hypothesized that central modification of fatty acids metabolism might occur after prolonged peripheral noxious stimulation. In the present study, the regulation of genes involved in fatty acids metabolism in the rat CNS was investigated during a chronic pain state. Using semiquantitative RT-PCR, we explored in the neuraxis the mRNA expression of brain acyl-CoA synthetases (ACS) and acyl-CoA oxidase (ACO), which are major fatty acid-metabolizing enzymes, following complete Freund's adjuvant (CFA) injection into a hind paw. Similar spinal up-regulation of the isoforms ACS2, ACS3, ACS4, and of ACO was detected early after 30 min, reaching a maximal after 6 h post-injection. Other peaks were also observed after 4 and 21 days post-inoculation, corresponding to the acute and chronic inflammation, respectively. Induction occurred only in the lumbar spinal cord ipsilaterally to the inflamed paw and was completely inhibited by a local anaesthesia of the sciatic nerve, suggesting a neural transmission of the inducing signal. Moreover, intrathecal injection of MK801, a noncompetitive NMDA antagonist, partially prevented these inductions, highlighting the involvement of the neurotransmitter glutamate in the central ACS and ACO up-regulation. These findings suggest that the fatty metabolism is stimulated in the CNS during a chronic pain state.

Evidence for the presence of both peroxisome proliferator-activated receptors alpha and beta in the rat spinal cord.

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors belonging to the nuclear receptor superfamily. Different subtypes of PPARs (alpha, beta, and gamma) have been described. Their distinct physiological functions depend on their differential ligand activation profiles but also on their specific tissue expression. Previous studies have described their presence in the central nervous system. However, their expression in the adult rat spinal cord in normal physiological conditions has never been investigated. We demonstrated by using reverse-transcription-polymerase chain reaction, and Western blotting, the mRNA and protein expression of PPARalpha and PPARbeta, but not PPARgamma in cervical, thoracic, and lumbar segments of the spinal cord. Using immunohistochemistry, we also showed for the first time the specific cellular distribution of these transcription factors in the different segments of the spinal cord. In the gray matter, the distribution of PPARalpha was homogenous whereas PPARbeta was specifically localized in motoneurons and in medial part of laminae IV, V, VI, VII, VIII, and X. These latter areas are known as nociceptive afferent pathways to supra-spinal structures such as the medulla reticular nucleus and the thalamus. In the white matter, PPARalpha was localized exclusively in astrocytes while PPARbeta was present in oligodendrocytes. The possible functions of PPARalpha and PPARbeta expressed in both white and gray matters of the spinal cord will be discussed but need further studies.

Postural instability in idiopathic Parkinson's disease: the role of medication and unilateral pallidotomy.

Postural instability (PI) is common in idiopathic Parkinson's disease (IPD). We measured sensory and motor contributions to PI in 50 patients with advanced IPD, off and on medication and in a subset pre- and 3, 6 and 12 months post-unilateral pallidotomy, using computerized dynamic posturography [specifically, the Sensory Organization Test (SOT) and the Unified Parkinson's Disease Rating Scale (UPDRS) subscale PIGD (Postural Instability and Gait Disorder)]. Off medication, all patients had abnormal PIGD scores. The group could be separated into those with normal SOT equilibrium scores (SOTN) and those, the majority, with abnormal postural control when sensory feedback was limited (SOTABN). Medication improved the PIGD scores but worsened the SOT scores in the majority of patients. Increases in spontaneous sway in some patients contributed to the negative effect of medication on SOT scores. However, this could not explain the detrimental effect of medication on SOT scores in at least 40% of patients. On the other hand, pallidotomy improved both PIGD and SOT scores in both groups. A predictor of good outcome from pallidotomy concerning PI was the degree of worsening of the effect that medication had on SOT5 scores. PI in IPD appears to be multifactorial. We propose that the PIGD score reflects sensory and motor aspects of postural control, with normal sensory feedback, while the SOT equilibrium scores measure the sensory organizational process of postural control in the presence of altered sensory inputs. There is a dissociation between the effects of medication and pallidotomy on motor and sensory components of postural control, which may reflect the underlying pathophysiological mechanism responsible for these different components of PI. We suggest that patients with advanced IPD and PI on medication should consider adjuvant surgical treatment for better postural control.

Surveillance neuroimaging to detect relapse in childhood brain tumors: a Pediatric Oncology Group study.

PURPOSE: To investigate the prognostic significance of surveillance neuroimaging for detection of relapse among children with malignant brain tumors. PATIENTS AND METHODS: A historical cohort study examined all children who experienced relapse from 1985 to 1999 on one of 10 Pediatric Oncology Group trials for malignant glioma, medulloblastoma, or ependymoma. RESULTS: For all 291 patients (median age at diagnosis, 8.2 years), median time to first relapse was 8.8 months (range, 0.6 to 115.6 months). Ninety-nine relapses were radiographic, and 192, clinical; median time to relapse was 15.7 versus 6.6 months, respectively (P = .0001). When stratified by pathology, radiographic and clinical groups showed differences in median time to relapse for malignant glioma (7.8 v 4.3 months, respectively; P = .041) and medulloblastoma (23.6 v 8.9 months, respectively; P = .0006) but not ependymoma (19.5 v 13.3 months, respectively; P = .19). When stratified by early (< 8.8 months) or late (> or = 8.8 months) time to relapse, 115 early relapses were clinical, and 32, radiographic; for late relapses, 77 were clinical, and 67, radiographic (P = .001). Overall survival (OS) from relapse was significantly longer for radiographic compared with clinical detection (median, 10.8 months; 1-year OS, 46% v median, 5.5 months; 1-year OS, 33%; P = .002), but this trend did not retain significance when analyzed by pathology subgroups. CONCLUSION: Surveillance neuroimaging detects a proportion of asymptomatic relapses, particularly late relapses, and may provide lead time for other therapies on investigational trials. During the first year after diagnosis, radiographic detection of asymptomatic relapse was infrequent. A prospective study is needed to formulate a rational surveillance schedule based on the biologic behavior of these tumors.