Faculty Bibliography

Vascular smooth muscle cell (VSMC) migration participates in atherosclerosis and arterial restenosis after balloon angioplasty. Because these processes are enhanced in insulin-resistant states, our goal was to determine whether insulin affects VSMC migration and, if so, how. The migration of primary cultured VSMCs from canine femoral artery was measured with the use of a wound migration assay and related to cGMP levels. Insulin (1 nmol/L) did not affect migration or cGMP production in control cells. When inducible nitric oxide synthase (iNOS) was induced by 24-hour preincubation with lipopolysaccharide and interleuken-1beta, basal migration decreased, cGMP production increased, and insulin inhibited migration by >90% and stimulated cGMP production by 3-fold. The nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine blocked the affect of insulin on the migration of VSMCs with iNOS. 8-Bromo-cGMP inhibited VSMC migration in control cells, and 1-H-1[1,2,4]oxadiazolo-[4, 3a]quinoxolin-1-one, a selective inhibitor of guanylate cyclase, blocked the inhibition by insulin of migration of cells with iNOS. We conclude that insulin does not normally affect cGMP production or the migration of these VSMCs. However, after the induction of iNOS, insulin stimulates cGMP production and inhibits migration via an NOS-and a cGMP-dependent mechanism.

Germ-line and somatic mutations of the hSNF5/INI1 gene have been reported in atypical teratoid/rhabdoid tumors (AT/RTs) of the brain, consistent with its role as a tumor suppressor gene. In the present study, we determined the frequency of deletions and mutations of INI1 in 52 children whose original diagnosis was medulloblastoma (MB) or primitive neuroectodermal tumor (PNET) of the central nervous system. Mutations were detected in DNA isolated from four tumors, all from children less than 3 years of age at diagnosis. Two of the four were reviewed and reclassified as atypical teratoid tumor, whereas there was insufficient material to establish this diagnosis in the two remaining cases. The relatively low frequency of mutations, even in a large series of infants, suggests that loss of sequences from chromosome 22 and/or mutations of INI1 do not account for the poor prognosis of children with MB or PNET who are less than 3 years of age at diagnosis. Nevertheless, chromosome 22 deletion and INI1-mutation analysis of infants with MB/PNET should be considered for all children who are less than 1 year of age. Detection of these mutations suggests that the child has an AT/RT, rather than a MB/PNET, a finding with important prognostic value

OBJECTIVE: We discuss the clinical aspects, pathology, and molecular genetics of 7 patients with primitive neuroectodermal tumors (PNETs) arising in the brainstem that were treated at our institution from 1986 through 1995. Most neuro-oncologists avoid performing biopsies in children with pontine tumors. This article raises the question as to whether biopsies should be performed, because treatment recommendations might differ if a PNET was diagnosed rather than a pontine glioma. PATIENTS AND METHODS: We reviewed the clinical neuro-oncology database and the files of the Division of Neuropathology at New York University Medical Center from 1986 through 1995 and identified 7 histologically confirmed PNETs arising in the brainstem among 146 pediatric brainstem tumors. The clinical, neuroradiological, and neuropathological data were reviewed. Postmortem examinations were performed in 2 cases. Formalin-fixed, paraffin-embedded tumor tissues were also available in 6 of 7 patients that were tested for p53 gene mutations using single-strand conformation polymorphism analysis. We also tested 9 cerebellar PNETs, 9 brainstem gliomas, and 3 normal brains for p53 gene mutations as controls. RESULTS: All 7 patients presented with focal cranial nerve deficits, and 2 were also hemiparetic. The median age at diagnosis was 2.7 (1-8 years). Magnetic resonance imaging (MRI) characteristics included a focal intrinsic exophytic nonenhancing brainstem lesion that had low T1-weighted and high T2-weighted signals. Hydrocephalus was present in 5 patients at diagnosis, 3 of whom had leptomeningeal dissemination. Meningeal dissemination occurred later in the course of the disease in 3 other patients. Five children required shunts at diagnosis and another 2 at recurrence. Despite therapy, all 7 PNET patients died within 17 months of diagnosis with a mean survival of 8 (4-17) months. No mutation in the p53 gene was detected. CONCLUSIONS: Brainstem PNETs tend to arise at a younger age than brainstem gliomas and medulloblastomas. The MRI pattern suggests a localized rather than a diffuse intrinsic nonenhancing brainstem tumor. Like other PNETs, brainstem PNETs have a high predilection to disseminate within the central nervous system. The absence of p53 mutations is similar to other PNETs. Despite their origin close to the cerebellum, brainstem PNETs exhibit a more aggressive behavior and result in worse clinical outcomes than do cerebellar PNETs

Diencephalic gliomas may be grouped into 2 clinical categories. Optic pathway/hypothalamus gliomas (OPG) arise primarily from a slower-growing juvenile pilocytic astrocytoma, and thalamic gliomas arise primarily from a fibrillary astrocytoma which can become clinically and histologically more aggressive. Children with OPG have an excellent long-term prognosis with a 10-year survival of over 85%. The major therapeutic challenge for these patients is to maximize their quality of life by preserving visual and endocrine function while minimizing treatment-related morbidity. Treatment is often initiated at diagnosis in infants and toddlers who have a major visual impairment or the diencephalic syndrome. The judicious application of chemotherapy may serve to forestall the need for radiotherapy or surgery. Children with neurofibromatosis-1 (NF-1) usually have a more indolent course. Tumors may grow more slowly or occasionally regress spontaneously. However, over 90% of children with OPG without NF-1 will require some form of therapy. Patients with thalamic gliomas present with a shorter history, often with hydrocephalus. Surgical intervention is often required to relieve intracranial pressure and establish the histologic identity of the tumor. Over 75% of these tumors will become locally aggressive. Current multimodality therapy is relatively ineffective. The bithalamic variant behaves similarly to a pontine glioma

OBJECT: The majority of intramedullary spinal cord tumors (IMSCT) in children and young adults are low-grade gliomas. Radical resection of similar tumors in the cerebral hemisphere or cerebellum is usually curative; however, the conventional management for IMSCTs remains partial resection followed by radiotherapy because of the concern for surgical morbidity. Nevertheless, radical resection of IMSCTs without routine adjuvant treatment has been the rule at our institution since 1980. In an attempt to resolve this controversy, the long-term morbidity and survival in a large series of children have been retrospectively reviewed. METHODS: The database records and current status of 164 patients 21 years of age and younger in whom an IMSCT was resected were reviewed. A gross-total resection (>95%) was achieved in 76.8% of the surgical procedures. Subtotal resections (80-95%) were performed in 20. 1%. The majority of patients (79.3%) had histologically low-grade lesions. There were no deaths due to surgery. When comparing the preoperative and 3-month postoperative functional grades, 60.4% stayed the same, 15.8% improved, and 23.8% deteriorated. Only 13 patients deteriorated by more than one functional grade. Patients with either no deficits or only mild deficits before surgery were rarely injured by the procedure, reinforcing the importance of early diagnosis and treatment. The major determinant of long-term patient survival was histological composition of the tumor. The 5-year progression-free survival rate was 78% for patients with low-grade gliomas and 30% for those with high-grade gliomas. Patients in whom an IMSCT was only partially resected (<80%) fared significantly worse. CONCLUSIONS: The long-term survival and quality of life for patients with low-grade gliomas treated by radical resection alone is comparable or superior to minimal resection and radiotherapy. The optimum therapy for patients with high-grade gliomas is yet to be determined

BACKGROUND: Brainstem gliomas often respond to radiotherapy but long term disease control is exceptional. The concomitant administration of a chemotherapy agent with radiosensitizing properties such as carboplatin may increase the efficacy of radiotherapy. METHODS: A dose escalation schedule of carboplatin was devised to determine the maximum tolerated dose (MTD) of intravenous carboplatin when given on a twice-weekly schedule during a course of hyperfractionated, involved field radiotherapy (100 centigrays [cGy] twice daily to 7200 cGy). The starting dose was 20 mg/m(2) and the dose was increased by 15 mg/m(2) after every 3 patients provided no Grade 3 or 4 (according to the National Institutes of Health Common Toxicity Criteria) toxicity occurred. Magnetic resonance imaging (MRI) scans (brain and spine) were obtained before treatment and at the time of disease progression. Clinical entry criteria included an MRI scan demonstrating a diffuse intrinsic pontine tumor and a typical 2-3-month history of evolving cranial neuropathies and a gait disorder. Biopsy-confirmed evidence of a high grade glioma was required for nonpontine brain stem tumors. RESULTS: A total of 34 patients were enrolled. The median age of the patients was 7.8 years (range, 3.6-15.4 years) and the median prodrome duration was 1.5 months (range, 0.25-36 months). The MTD was 110 mg/m(2) or a total cumulative dose of 1540 mg/m(2) over 7 weeks. The dose-limiting toxicity was hematologic. The median progression free survival was 8 months (range, 0-104+ months) and the overall survival was 12 months (range, 5-104+ months). At last follow-up there were 5 long term survivors (15%) who remained in continuous remission after a mean follow-up period of 79 months (range, 46-104 months). Fifteen of the 29 patients (52%) with recurrence and or disease progression developed leptomeningeal/intraaxial tumor spread beyond the local radiation field. CONCLUSIONS: The cumulative MTD for carboplatin is 1540 mg/m(2) when administered concomitantly with involved field, hyperfractionated radiotherapy in a twice-weekly schedule for 7 weeks. Subsequent Phase II and III clinical trials can be conducted safely at this level.

Knowledge of the competitive demands of different sports or activities is important for designing appropriate training programmes to ensure that animals reach a sufficient level of fitness to reduce the risk of overexertion and injury or illness and to achieve the best possible performance in relation to an individual's genetic potential. Whilst the physiological demands of many equestrian sports have been described, to the best of our knowledge the cardiovascular demands of polo have not. The aims of the present study were therefore to record heart rate during and after competitive polo games in a group of low-goal (non-elite) polo ponies in order to describe the absolute heart rates during play, the relationship of these heart rates to maximal heart rate and the characteristics of a typical chukka in terms of effort. Six low-goal polo ponies were studied during a total of 59 chukkas. Heart rate was monitored continuously before, during and after competition using a commercial heart rate monitor. Maximal heart rate was determined with field and treadmill incremental exercise tests and used to express work intensity in terms of time during play that each ponies heart rate was less than 75% HRmax, between 75 and 90% HRmax and greater than 90% HRmax. Mean maximum heart rate was not different during play or during field and treadmill exercise tests; 215+/-7 (mean +/- s.d.), 211+/-7 and 213+/-2 beats/min, respectively (P>0.05). Mean heart rate for all ponies over all chukkas was 166+/-6 beats/min with a mean chukka duration of 611+/-18 s. Of this time, 44+/-7% of the time was spent below 75% HRmax, 39+/-8% between 75 and 90% HRmax and 17+/-8% of time above 90% HRmax. When only one chukka had been played, there was a good correlation between mean heart rate during play and 3 min recovery heart rate (r = 0.63, P<0.001). Based on these observations, it is proposed that low-goal polo places moderate to high stress on the cardiovascular system.