Fractional Flow on TOF-MRA as a Measure of Stroke Risk in Children with Intracranial Arterial Stenosis

BACKGROUND AND PURPOSE

Conventional angiography is the criterion standard for measuring intracranial arterial stenosis. We evaluated signal intensity ratios from TOF-MRA as a measure of intracranial stenosis and infarct risk in pediatric stroke.

MATERIALS AND METHODS

A retrospective study was undertaken in children with intracranial arterial stenosis, who had TOF-MRA and conventional angiography performed within 6 months. Arterial diameters were measured for percentage stenosis. ROI analysis on TOF-MRA measured signal intensity in pre- and poststenotic segments, with post-/pre-signal intensity ratios calculated. The Pearson correlation was used to compare percentage stenosis on MRA with conventional angiography and signal intensity ratios with percentage stenosis; the point-biserial correlation was used for infarcts compared with percentage stenosis and signal intensity ratios. Sensitivity, specificity, and positive and negative predictive values were calculated for determining severe (≥70%) stenosis from MRA and signal intensity ratios against the criterion standard conventional angiography. P < .05 was considered statistically significant.

RESULTS

Seventy stenotic segments were found in 48 studies in 41 children (median age, 11.0 years; range, 5 months to 17.0 years; male/female ratio, 22:19): 20/41 (48.8%) bilateral, 11/41 (26.8%) right, and 10/41 (24.4%) left, with the most common site being the proximal middle cerebral artery (22/70, 31%). Moyamoya disease accounted for 27/41 (65.9%). Signal intensity ratios and conventional angiography stenosis showed a moderate negative correlation (R = -0.54, P < .001). Receiver operating characteristic statistics showed an area under the curve of 0.86 for using post-/pre-signal intensity ratios to determine severe (≥70%) carotid stenosis, yielding a threshold of 1.00. Sensitivity, specificity, and positive and negative predictive values for severe stenosis were the following-MRA: 42.8%, 58.8%, 30.0%, and 71.4%; signal intensity ratio >1.00: 97.1%, 77.8%, 71.7%, and 97.4%; combination: 75.5%, 100%, 100%, and 76.8%, respectively. Signal intensity ratios decreased with increasing grade of stenosis (none/mild-moderate/severe/complete, P < .001) and were less when associated with infarcts (0.81 ± 0.52 for arteries associated with downstream infarcts versus 1.31 ± 0.55 for arteries without associated infarcts, P < .001).

CONCLUSIONS

Signal intensity ratios from TOF-MRA can serve as a noninvasive measure of intracranial arterial stenosis and allow identification of high-risk lesions in pediatric stroke.

Predicting Ischemic Risk Using Blood Oxygen Level-Dependent MRI in Children with Moyamoya

BACKGROUND AND PURPOSE

Moyamoya is a progressive steno-occlusive arteriopathy. MR imaging assessment of cerebrovascular reactivity can be performed by measuring the blood oxygen level-dependent cerebrovascular reactivity response to vasoactive stimuli. Our objective was to determine whether negative blood oxygen level-dependent cerebrovascular reactivity status is predictive of ischemic events in childhood moyamoya.

MATERIALS AND METHODS

We conducted a retrospective study of a consecutive cohort of children with moyamoya who underwent assessment of blood oxygen level-dependent cerebrovascular reactivity. The charts of patients with written informed consent were reviewed for the occurrence of arterial ischemic stroke, transient ischemic attack, or silent infarcts. We used logistic regression to calculate the OR and 95% CI for ischemic events based on steal status. Hazard ratios for ischemic events based on age at blood oxygen level-dependent cerebrovascular reactivity imaging, sex, and moyamoya etiology were calculated using Cox hazards models.

RESULTS

Thirty-seven children (21 female; median age, 10.7 years; interquartile range, 7.5-14.7 years) were followed for a median of 28.8 months (interquartile range, 13.7-84.1 months). Eleven (30%) had ischemic events, 82% of which were TIA without infarcts. Steal was present in 15 of 16 (93.8%) hemispheres in which ischemic events occurred versus 25 of 58 (43.1%) ischemic-free hemispheres (OR = 19.8; 95% CI, 2.5-160; P = .005). Children with idiopathic moyamoya were at significantly greater risk of ischemic events (hazard ratio, 3.71; 95% CI, 1.1-12.8; P = .037).

CONCLUSIONS

Our study demonstrates that idiopathic moyamoya and the presence of steal are independently associated with ischemic events. The use of blood oxygen level-dependent cerebrovascular reactivity could potentially assist in the selection of patients for revascularization surgery and the direction of therapy in children with moyamoya.

Predictive Value of MRI in Diagnosing Brain AVM Recurrence after Angiographically Documented Exclusion in Children

BACKGROUND AND PURPOSE

MRI is routinely performed following brain AVM after treatment in children. Our aim was to determine the predictive values of contrast-enhanced MR imaging and TOF-MRA for brain AVM recurrence in children, compared with conventional angiography and the role of 3D rotational angiography-MR imaging fusion in these cases.

MATERIALS AND METHODS

We included all pediatric patients with brain AVMs during an 18-year period with angiographically documented obliteration after treatment. Patients underwent 3T MR imaging, including contrast-enhanced MR imaging, TOF-MRA, and conventional angiography, with a subset undergoing 3D rotational angiography. The predictive values of contrast-enhanced MR imaging and TOF-MRA for brain AVM recurrence were determined. CTA sections reconstructed from 3D rotational angiography were coregistered with and fused to 3D-T1WI for analysis.

RESULTS

Thirty-nine children (10.8 ± 3.9 years of age; range, 2-17 years; male/female ratio, 19:20; mean Spetzler-Martin grade, 1.9 ± 0.6) met the inclusion criteria. Of these, 13 had angiographically confirmed brain AVM recurrence, 8 following surgery and 5 following embolization. Sensitivity, specificity, and positive and negative predictive values for recurrence were the following: contrast-enhanced MR imaging: 84.6%, 38.5%, 40.7%, 81.8%; TOF-MRA: 50.0%, 96.1%, 85.7%, 79.3%; both: 75.0%, 90.9%, 85.7%, 83.3%. 3D rotational angiography-MR imaging fused images confirmed or excluded recurrence in all available cases (13/13). Embolization-only treatment was a significant predictor of recurrence (OR = 32.4, P = .006). MR imaging features predictive of recurrence included a tuft of vessels on TOF-MRA and nodular juxtamural/linear enhancement with a draining vein on contrast-enhanced MR imaging.

CONCLUSIONS

MR imaging is useful for surveillance after brain AVM treatment in children, but conventional angiography is required for definitive diagnosis of recurrence. TOF-MRA and contrast-enhanced MR imaging provide complementary information for determining brain AVM recurrence and should be interpreted in conjunction. 3D rotational angiography-MR imaging fusion increases the diagnostic confidence regarding brain AVM recurrence and is therefore suited for intraoperative neuronavigation.

Breath-Hold Blood Oxygen Level-Dependent MRI: A Tool for the Assessment of Cerebrovascular Reserve in Children with Moyamoya Disease

BACKGROUND AND PURPOSE

There is a critical need for a reliable and clinically feasible imaging technique that can enable prognostication and selection for revascularization surgery in children with Moyamoya disease. Blood oxygen level-dependent MR imaging assessment of cerebrovascular reactivity, using voluntary breath-hold hypercapnic challenge, is one such simple technique. However, its repeatability and reliability in children with Moyamoya disease are unknown. The current study sought to address this limitation.

MATERIALS AND METHODS

Children with Moyamoya disease underwent dual breath-hold hypercapnic challenge blood oxygen level-dependent MR imaging of cerebrovascular reactivity in the same MR imaging session. Within-day, within-subject repeatability of cerebrovascular reactivity estimates, derived from the blood oxygen level-dependent signal, was computed. Estimates were associated with demographics and intellectual function. Interrater reliability of a qualitative and clinically applicable scoring scheme was assessed.

RESULTS

Twenty children (11 males; 12.1 ± 3.3 years) with 30 MR imaging sessions (60 MR imaging scans) were included. Repeatability was "good" on the basis of the intraclass correlation coefficient (0.70 ± 0.19). Agreement of qualitative scores was "substantial" (κ = 0.711), and intrarater reliability of scores was "almost perfect" (κ = 0.83 and 1). Younger participants exhibited lower repeatability (P = .027). Repeatability was not associated with cognitive function (P > .05). However, abnormal cerebrovascular reactivity was associated with slower processing speed (P = .015).

CONCLUSIONS

Breath-hold hypercapnic challenge blood oxygen level-dependent MR imaging is a repeatable technique for the assessment of cerebrovascular reactivity in children with Moyamoya disease and is reliably interpretable for use in clinical practice. Standardization of such protocols will allow further research into its application for the assessment of ischemic risk in childhood cerebrovascular disease.

Complexity of gap junctions between horizontal cells of the carp retina

In the vertebrate retina, horizontal cells (HCs) reveal homologous coupling by gap junctions (gj), which are thought to consist of different connexins (Cx). However, recent studies in mouse, rabbit and zebrafish retina indicate that individual HCs express more than one connexin. To provide further insights into the composition of gj connecting HCs and to determine whether HCs express multiple connexins, we examined the molecular identity and distribution of gj between HCs of the carp retina. We have cloned four carp connexins designated Cx49.5, Cx55.5, Cx52.6 and Cx53.8 with a close relationship to connexins previously reported in HCs of mouse, rabbit and zebrafish, respectively. Using in situ hybridization, Cx49.5 expression was detected in different subpopulations of retinal neurons including HCs, whereas the Cx52.6 transcript was localized exclusively in HCs. Using specific antibodies, Cx55.5 and Cx53.8 were detected on dendrites of all four HC subtypes and axon terminals. Immunoelectron microscopy confirmed the presence of Cx55.5 and Cx53.8 in gap junctions between these processes and Cx55.5 was additionally observed in HC dendrites invaginating cone pedicles, suggesting its participation in the modulation of photoreceptor output in the carp retina. Furthermore, using single-cell RT-PCR, all four connexins were detected in different subtypes of HCs, suggesting overlapping expression patterns. Thus, the composition of gj mediating homologous coupling between subtypes of carp HCs appears to be more complex than expected. Moreover, BLAST searches of the preliminary carp genome, using novel sequences as query, suggest that most of the analyzed connexin genes are duplicated in carp.

Decreased Superior Sagittal Sinus Diameter and Jugular Bulb Narrowing Are Associated with Poor Clinical Outcome in Vein of Galen Arteriovenous Malformation

BACKGROUND AND PURPOSE

Few clinical and imaging findings are known to be associated with poor outcome in neonates and infants with vein of Galen arteriovenous malformations. In the present consecutive series of 35 patients, we evaluated both the diameter of the superior sagittal sinus at onset and the diameter of the jugular bulb on follow-up as potential factors related to poor outcome.

MATERIALS AND METHODS

Thirty-five consecutive neonates and infants who were prospectively collected in a single-center data base were included in this review. Outcome was assessed by using the Bicêtre Outcome Score. Both the absolute diameter of the superior sagittal sinus and its ratio to the biparietal diameter were measured at onset, compared with age-matched controls, and correlated to patient outcome.

RESULTS

The diameter of the superior sagittal sinus at onset and its ratio to the biparietal diameter were significantly smaller in the vein of Galen arteriovenous malformation population compared with the matched population (P = .0001) and were correlated significantly with a risk of poor clinical outcome (P = .008). Development of jugular bulb narrowing was also related to poor clinical outcome (P < .0001).

CONCLUSIONS

Decreased superior sagittal sinus diameter may reflect a decrease of cerebral blood flow due to cerebral arterial steal and intracranial hydrovenous disorders. This finding may be considered cerebral blood flow deterioration and thus taken into consideration in the management decisions for patients with vein of Galen arteriovenous malformations. Likewise, our data suggest that progressive jugular bulb narrowing may indicate earlier intervention to prevent severe narrowing.

Expression of timp-1, timp-2, 72-kda and 92-kda type-iv collagenase transcripts in human astrocytoma cell-lines - correlation with astrocytoma cell invasiveness

Malignant astrocytomas are highly invasive neoplasms which infiltrate diffusely into regions of normal brain. As evidence to support one mechanism by which tumor cells are known to invade, we have previously shown that astrocytoma cell lines secrete a variety of matrix metalloproteinases (MMPs) and metalloproteinase inhibitors (Apodaca et al: Cancer Res 50: 2322-2329, 1990). In the present study we determined the expression of tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, 72-kDa and 92-kDa type IV collagenase transcripts among human astrocytoma cell lines. In addition, we sought to correlate MMP and TIMP transcript levels with astrocytoma invasiveness. RNA from seven well characterized human astrocytoma cell lines was extracted before and after phorbol ester treatment and Northern blot analyses were performed using cDNA probes for the MMPs and TIMPs. All astrocytoma cell lines and normal human leptomeningeal cells were tested for their relative invasive potential using an in vitro invasion assay. There was variable expression of MMP and TIMP transcripts among astrocytoma cell lines. SF-188 was the only cell line to demonstrate a relative abundance of 72- and 92-kDa type IV collagenase transcripts over TIMP-1 and TIMP-2 transcript levels. Interestingly, this cell line was the most highly invasive in the in vitro invasion assay system. U 343 MG-A demonstrated relative abundance of TIMP-1 and -2 transcripts over 72- and 92-kDa type IV collagenase transcripts and was the least invasive cell line. Prior treatment of astrocytoma cell lines with phorbol ester upregulated TIMP-1 and 92-kDa type IV collagenase transcripts, but not TIMP-2 and 72-kDa type IV collagenase transcripts. We conclude that there is only partial correlation between MMP and TIMP transcript levels and in vitro cell invasiveness among the astrocytoma cell lines studied. Our analysis has led to the identification of an astrocytoma cell line, SF-188, which appears to overexpress the 72-kDa and 92-kDa type IV collagenase transcripts relative to low level TIMP-1 and TIMP-2 transcripts. This particular cell line will continue to be of considerable value in dissecting some of the molecular mechanisms involved in astrocytoma cell invasion.

Magnetoencephalographic spike sources associated with auditory auras in paediatric localisation-related epilepsy

OBJECTIVE

To characterise magnetoencephalographic spike sources in paediatric patients with auditory auras and recurrent localisation-related epilepsy.

METHODS

Six patients (four boys and two girls (ages 7-14 years) were retrospectively studied. All patients had auditory auras as part of their initial seizure manifestation, including four patients who underwent previous brain surgery. Scalp video electroencephalography and magnetoencephalography (MEG) were carried out in six patients, intraoperative electrocorticography in three patients and extraoperative intracranial video electroencephalography in one patient. MEG auditory-evoked fields (AEFs) were studied in four patients.

RESULTS

Three patients had elementary auditory auras, one had complex auditory aura and two had both complex and elementary auras. All six patients had clustered MEG spike sources with coexisting scattered spike sources. MEG clusters were localised in the superior temporal gyrus with surrounding scatters in four patients (two left and two right); two patients had scattered spikes in the superior temporal gyrus in addition to clustered MEG spike sources in the left inferior and middle frontal gyri or parieto-occipital region. AEFs were located within an MEG cluster in one patient and within 3 cm of a cluster in two patients. Surgical resection, including the regions of MEG clusters, was carried out in four patients. Three of four patients who had previous surgeries were seizure free at 2 years after excision of the MEG cluster region.

CONCLUSIONS

MEG spike sources clustered in the superior temporal gyrus in six patients with auditory auras. These spike sources were in close proximity or seemed to engulf the magnetic AEF. Areas with MEG spike sources contained the residual or recurrent epileptogenic zone after incomplete cortical excision for lesional epilepsy.

Hypothermia pediatric head injury trial: the value of a pretrial clinical evaluation phase

BACKGROUND

The utility of a pretrial clinical evaluation or run-in phase prior to conducting trials of complex interventions such as hypothermia therapy following severe traumatic brain injury in children and adolescents has not been established.

METHODS

The primary objective of this study was to prospectively evaluate the ability of investigators to adhere to the clinical protocols of care including the cooling and rewarming procedures as well as management guidelines in patients with severe traumatic brain injury (Glasgow Coma Scale<or=8) treated with 24 h of hypothermia therapy. A secondary objective was to evaluate the ability of study research assistants to complete the study case report form using a procedures manual. The study was conducted at 18 sites in Canada, the United Kingdom and France prior to proceeding to a randomized controlled trial (RCT). After 2 patients were enrolled at each center, an independent clinical evaluation committee examined the process of care and the completeness of data collection. Centers were permitted to enroll patients in the RCT once they met pre-established adherence criteria.

RESULTS

Seventeen of the 18 centers completed the pretrial clinical evaluation phase demonstrating compliance with study procedures and proceeded to an RCT of hypothermia therapy. One center enrolled only 1 patient in the pretrial clinical evaluation phase due to small numbers of patients with traumatic brain injury, and therefore, did not proceed to the RCT. Three centers were required to enroll more than 2 patients in the pretrial clinical evaluation phase prior to proceeding to the RCT because of problems with adherence to the clinical protocols at two centers and the training of new study personnel at another center. Of the 39 patients enrolled during the pretrial clinical evaluation phase, 8 (20.5%) died and 22 (62.9%) had a good outcome defined as normal, mild or moderate disability assessed using the Pediatric Cerebral Performance Category score at 6 months following injury.

DISCUSSION

The pretrial clinical evaluation phase was useful to ensure compliance with complex hypothermia therapy and consensus-based clinical management guidelines of care successfully implemented across 17 of 18 centers. This study maneuver allowed us to complete a subsequent RCT in 225 children following severe traumatic brain injury.

Ocular manifestations of crush head injury in children

AIMS

To review the ocular manifestations of crush head injuries in children.

METHODS

Retrospective clinical and pathological reviews. Group 1: A total of 16 children admitted with crush head injuries from television tip over. Group 2: Nine autopsy findings in crush head injury.

RESULTS

Group 1: A total of 11 children had fundus examination: three by neurosurgeons, eight by ophthalmologists. Scattered posterior pole preretinal and blot haemorrhages extending to mid equator region observed in one child. No evidence of traumatic retinoschisis or retinal folds in any patient. Group 2: All with multiple skull fractures and six with subdural haemorrhage. Posterior pole retinal haemorrhages in four children, extending to the ora serrata in one after motor vehicle accident. No child had retinal folds. Subinternal limiting membrane haemorrhages in three children. Optic nerve sheath haemorrhage in three children.

CONCLUSIONS

Intraretinal and preretinal haemorrhages, predominantly in the posterior pole, can occur in crush injury to the paediatric head. Haemorrhage under the internal limiting membrane or extending to the ora serrata were only seen in situations where crush injury was part of a fatal trauma scenario related to motor vehicles. Retinal folds and the typical macular retinoschisis associated with abusive head injury were not observed.

Pituitary stalk thickening and primary central nervous system lymphoma

We report a 14-year-old girl in whom a diagnosis of primary central nervous system lymphoma was confirmed while receiving growth hormone (GH) for GH deficiency, detected after presenting with short stature. MRI revealed an enhancing and thickened pituitary stalk with absence of the normal bright signal in the posterior pituitary. Regular MRI surveillance detected progression of the neurohypophyseal changes 13 months into GH treatment. Biopsy confirmed this to be B-cell large cell lymphoma. This case highlights the diagnostic and management challenges inherent in treating such children.

Molecular biology and neurosurgery in the third millennium

The application of techniques in molecular biology to human neurosurgical conditions has led to an increased understanding of disease processes that affect the brain and to novel forms of therapy that favorably modify the natural history of many of these conditions. Molecular strategies are currently being either used or sought for brain tumors, stroke, neurodegenerative diseases, vascular malformations, spinal degenerative diseases, and congenital malformations of the central nervous system. Considering that the structure of deoxyribonucleic acid was ascertained by Watson and Crick as recently as 1953, the progress that has been made to implement molecular medicine in clinical practice has been meteoric. More than 2000 patients have been treated in approved gene therapy trials throughout the world. Many of these patients have been treated for neurological diseases for which conventional medical therapies have been of limited utility. As part of this continuing series on advances in neurosurgery in the third millennium, we first reflect on the history of the nascent field of molecular biology. We then describe the powerful techniques that have evolved from knowledge in this field and have been used in many publications in Neurosurgery, particularly within the past decade. These methods include commonly used techniques such as advanced cytogenetics, differential display, microarray technology, molecular cell imaging, yeast two-hybrid assays, gene therapy, and stem cell utilization. We conclude with a description of the rapidly growing field of bioinformatics. Because the Human Genome Project will be completed within 5 years, providing a virtual blueprint of the human race, the next frontier (and perhaps our greatest challenge) will involve the development of the field of "proteomics," in which protein structure and function are determined from the deoxyribonucleic acid blueprint. It is our conviction that neurosurgeons will continue to be at the forefront of the treatment of patients with neurological diseases using molecular strategies, by performing essential research leading to increased understanding of diseases, by conducting carefully controlled studies to test the effects of treatments on disease processes, and by directly administering (by neurosurgical, endovascular, endoscopic, or stereotactic means) the treatments to patients.

Co-expression of nestin and vimentin intermediate filaments in invasive human astrocytoma cells

Intermediate filaments (IFs) are highly diverse intracytoplasmic proteins within the cytoskeleton which exhibit cell type specificity of expression. A growing body of evidence suggests that IFs may be involved as collaborators in complex cellular processes controlling astrocytoma cell morphology, adhesion and proliferation. As the co-expression of different IF subtypes has been linked to enhanced motility and invasion in a number of different cancer subtypes, we undertook the present study to examine the expression of vimentin and nestin in a panel of human astrocytoma cell lines whose tumorigenicity, invasiveness and cytoskeletal protein profiles are well known. Astrocytoma cells were examined for IF protein expression by immunofluorescence confocal and immunoelectron microscopy. The motility of all cell lines was determined by computerized time-lapse videomicroscopy. Invasive potential of astrocytoma cells was determined using Matrigel as a barrier to astrocytoma cell invasion in vitro. Vimentin was expressed by all astrocytoma cell lines. On the other hand, nestin was variably expressed among the different cell lines. The most motile and invasive astrocytoma cell line in our study was antisense GFAP-transfected U251 (asU251) astrocytoma cells which showed marked up-regulation of nestin expression compared to the U251 parental cell line and controls. The U87 astrocytoma cell line also demonstrated high nestin expression levels and was associated with an increased basal motility rate and a high degree of invasiveness through Matrigel. U343 astrocytoma cells did not express nestin, but had high levels of GFAP. It had the lowest motility rate and invasiveness of all the astrocytoma cell lines examined. Taken together, these data suggest that for the astrocytoma cell lines examined in this study, nestin and vimentin co-expression may serve as a marker for an astrocytoma cell type with enhanced motility and invasive potential. Further studies are required to determine the mechanism by which dual-IF protein expression alters other cytoskeletal or cell surface receptor protein components important in the process of astrocytoma invasion.

Verotoxins inhibit the growth of and induce apoptosis in human astrocytoma cells

Verotoxin 1 (VT1) is an E. coli toxin comprising an A subunit with N-glycanase activity, and five smaller B subunits capable of binding to the functional receptor globotriaosylceramide (Galalpha1-4-Galbeta1-4-Glcceramide-Gb3). VT is implicated in hemorrhagic colitis and the more serious hemolytic uremic syndrome. VT1 is active against various tumor cell lines in vitro and in vivo. To extend the anti-cancer spectrum of activity of VT to human brain tumors, in the present analysis we studied the effects of VT on the growth of 6 permanent human astrocytoma cell lines. All astrocytoma cell lines analyzed express Gb3 and were sensitive to VT-1 at a dose of 50 ng/ml, but sensitivity was not proportional to the relative Gb3 concentration. VT induced apoptosis in these cells was shown by electron microscopy. Morphological evidence (nuclear shrinkage and chromatin condensation) of apoptosis could be clearly distinguished 1.5 hrs after toxin addition. Ultrastructural preservation of organelles was observed in conjunction with blebbing of the plasma membrane, condensation of chromatin within the nucleus and nuclear shrinkage. Apoptosis was also induced by the recombinant toxin B subunit alone, suggesting that the ligation of Gb3 is the primary induction mechanism. These studies indicate that verotoxin/Gb3 targetting may provide a novel basis for the inhibition of astrocytoma tumour cell growth.

Activity of the retinoblastoma family proteins, pRB, p107, and p130, during cellular proliferation and differentiation

Genetic evidence from retinoblastoma patients and experiments describing the mechanism of cellular transformation by the DNA tumor viruses have defined a central role for the retinoblastoma protein (pRB) family of tumor suppressors in the normal regulation of the eukaryotic cell cycle. These proteins, pRB, p107, and p130, act in a cell cycle-dependent manner to regulate the activity of a number of important cellular transcription factors, such as the E2F-family, which in turn regulate expression of genes whose products are important for cell cycle progression. In addition, inhibition of E2F activity by the pRB family proteins is required for cell cycle exit after terminal differentiation or nutrient depletion. The loss of functional pRB, due to mutation of both RB1 alleles, results in deregulated E2F activity and a predisposition to specific malignancies. Similarly, inactivation of the pRB family by the transforming proteins of the DNA tumor viruses overcomes cellular quiescence and prevents terminal differentiation by blocking the interaction of pRB, p107, and p130 with the E2F proteins, leading to cell cycle progression and, ultimately, cellular transformation. Together these two lines of evidence implicate the pRB family of negative cell cycle regulators and the E2F family of transcription factors as central components in the cell cycle machinery.

Co-amplification of MYCN and a DEAD box gene (DDX1) in primary neuroblastoma

DEAD box proteins are putative RNA helicases that have been implicated in cellular processes involving alteration of RNA secondary structure, such as translation initiation and splicing. These proteins share eight conserved amino acid motifs, including Asp(D)-Glu-(E)-Ala(A)-Asp(D) which is part of a more extended motif. Recently, we have shown that the novel DDX1 gene containing a DEAD box motif maps to the same chromosome band as MYCN at 2p24 and is co-amplified with MYCN in retinoblastoma cell lines. Here, we show that the DDX1 gene is co-amplified with the MYCN gene in 2 of three neuroblastoma cell lines and that DDX1 RNA levels correlate with DDX1 gene copy number. Since amplification of MYCN is an indicator of poor prognosis in neuroblastoma, it was of interest to determine whether co-amplification with DDX1 occurred in clinical samples of neuroblastoma and whether such a finding carried any additional prognostic significance. We determined the gene copy number of DDX1 in 32 neuroblastoma patient samples (representative of all stages): 13 were MYCN amplified and 19 had normal copy numbers of the MYCN gene. Of the 13 neuroblastomas that were MYCN amplified, seven were also DDX1 amplified. Of the 19 that were not MYCN amplified, none were DDX1 amplified. This is the first example of a gene that is co-amplified with MYCN at a high frequency in neuroblastoma. While there was a trend towards a worse clinical outcome with co-amplification, the numbers were too small to reach significance.

Characterization of a pineal region malignant rhabdoid tumor. Towards understanding brain tumor cell invasion

The malignant rhabdoid tumor (MRT) of the central nervous system is a highly aggressive neoplasm of early infancy which is characterized by brain invasion and widespread dissemination along cerebrospinal fluid pathways. As the process of tumor invasion is mediated in part by the elaboration of proteases and protease inhibitors by tumor cells, we sought to determine the expression of the type-IV collagenases and their inhibitors (tissue inhibitors of metalloproteases, TIMPs) in an MRT from the pineal region of a 9-month-old male. In addition, as only a few reports exist concerning the cytogenetic abnormalities in MRTs, the cytogenetic features of this MRT were examined. When placed into tissue culture, the MRT grew vigorously in early passages. The cytogenetic analysis of the cells in passage one revealed a near diploid karyotype with some metaphases demonstrating monosomy 22. Northern analysis of type-IV collagenase transcripts revealed that the MRT expressed the highest levels of the 72- and 92-kD type-IV collagenase transcripts of any pediatric brain tumor examined. However, the MRT did not express any significant amounts of the TIMP-1 or TIMP-2 transcripts. By in situ hybridization analysis, the MRT demonstrated marked intratumoral expression of the type-IV collagenase but not TIMP transcripts. The results from this study suggest that this particular MRT may be a highly invasive brain tumor, at least in part on the basis of overexpression of the type-IV collagenases relative to the TIMPs.

The value of reoperation for recurrent glioblastoma

To determine the value of reoperation alone (no further surgical procedures or radiotherapy), 43 patients (27 men, 16 women) with recurrent supratentorial glioblastomas who underwent a second craniotomy for recurrent tumour were reviewed retrospectively. The patients ranged in age from 27 to 66 years (median 53 years). All patients were treated initially by surgical resection and external radiation (50 Gy in 25 fractions through parallel opposed regional fields). In addition, 10 patients (23%) received chemotherapy, 3 patients (7%) received photodynamic therapy and 9 patients (21%) received interstitial brachytherapy postoperatively. Although none of the patients had further surgical procedures or radiotherapy after reoperation for tumour recurrence, 5 of the 43 did receive single-agent chemotherapy. The median survival after the first operation was 57 weeks. The median interval between first and second operations was 32 weeks. Median survival after reoperation was 19 weeks. An interval of more than 50 weeks between the two operations correlated with a significant (p < 0.05) increase in survival. The death rate for reoperation was 4.6%. The infection rate was 9.3%. The authors conclude that reoperation alone confers a modest but valuable increase in survival, especially if the interval between operations is greater than 50 weeks.

Airway responsiveness to intravenous and inhaled acetylcholine in the guinea pig after cigarette smoke exposure

Exposure of conscious guinea pigs to cigarette smoke results in bronchial hyperresponsiveness. To examine the mechanisms involved, we measured airway responses to increasing doses of intravenous or inhaled acetylcholine in guinea pigs exposed to cigarette smoke (n = 20) or to air (n = 20). After exposure the guinea pigs were anesthetized, paralyzed, and studied in a pressure-sensitive body plethysmograph while ventilated through a tracheostomy. Two and 6 puffs of an aerosol of increasing concentrations (0.05 to 500 micrograms/ml) of acetylcholine were delivered via the tracheostomy. Intravenous acetylcholine was delivered in boluses of 0.1 ml of increasing concentrations (0.5 to 50,000 micrograms/ml) via a catheter in an external jugular vein. Pulmonary resistance (RL), dynamic compliance (Cdyn), and heart rate (HR) were measured at baseline (after aerosolized or intravenous saline) and after each dose of acetylcholine. The peak responses to both inhaled and intravenous acetylcholine were rapid in onset (less than 15 s), short-lived (3 to 4 breaths), and were noncumulative. The baseline RL, Cdyn, and HR were not different in the smoke and air exposure groups. In the intravenous acetylcholine group, there were no differences in RL, Cdyn, and HR responses between the air and smoke exposure groups. In the inhaled acetylcholine group, the dose-response curve was shifted to the left (p less than 0.05) and reached a higher maximal response (p less than 0.01) after smoke exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of differing purified cellulose, pectin and hemicellulose fiber diets on mucosal morphology in the rat small and large intestine

The effects of increasing amounts of differing single-fiber sources in chemically-defined and nutritionally-equivalent diets on morphometric measurements of the rat small and large intestinal mucosa were examined. Male Wistar rats received a fiber-free diet, or diets containing 4.5% or 9.0% cellulose, pectin, or hemicellulose. Cellulose and pectin increased jejunal (but not ileal) villus and crypt heights, whereas hemicellulose increased ileal (but not jejunal) mucosal height. Moreover, cellulose and pectin (but not hemicellulose) increased crypt heights in cecum and proximal (but not distal) colon. Parallel increases in the mitotic index were seen with cellulose and pectin diets, but there was a decrease with hemicellulose, suggesting different mechanisms for altered patterns of cell renewal induced by orally-administered single-fiber sources. These changes indicate that differing single-fiber sources exert differential structural effects along the length of the small and large intestine in the rat.

Effect of breathing dry air on structure and function of airways

We compared the effect of breathing dry air (0.70 mg H2O/l) with that of breathing room air (8.62 mg H2O/l) in guinea pigs anesthetized with urethane. The data showed that breathing dry air caused a reduction of extravascular water (EVW) in the trachea (P less than 0.01) but not the lung. Structural analysis showed that this water loss occurred from the loose connective tissue of the submucosa. Histamine dose response curves performed on the animals showed that breathing dry air caused an increase in the maximum response (delta max RL) (P less than 0.01) without changing either the dose required to produce 50% of the delta max RL or the ratio of delta max RL to this dose. We conclude that breathing dry air produces an acute reduction of EVW of the loose connective tissue of the airways and an increase in the maximum response to histamine.

Improved survival in the treatment of advanced Hodgkin's disease at a nonuniversity institution (1970-1979)

From 1970 through 1979, 89 patients with Hodgkin's disease were treated at the Marshfield Clinic/St. Joseph's Hospital. After the pathologic material was reviewed, the patients were analyzed to compare Group I (1970-1973) with Group II (1974-1979). Demographic characteristics in the two groups were similar. In the decade, 76% of patients achieved complete remission. In advanced-stage disease, 50% of patients achieved complete remission in Group I compared with 68% in Group II. At 5 years, 50% of patients were alive without COPP (cyclophosphamide, vincristine, procarbazine, prednisone) chemotherapy; with this treatment, 75% of patients survived (P = 0.02). There was improved survival comparing Group I (56% at 5 years) with Group II (76% at 5 years) patients with advanced disease (P = 0.004). More aggressive combination chemotherapy (COPP) was related to the improvement in survival (P less than 0.001). The advances in treatment made by cooperative groups and universities are being transferred to nonuniversity institutions, with appropriate improvement in survival of Hodgkin's disease.