Sensitivity to radiation-induced apoptosis and neuron loss declines rapidly in the postnatal mouse neocortex.

Therapeutic brain irradiation can cause progressive decline in cognitive function, particularly in children, but the reason for this effect is unclear. The study explored whether age-related differences in apoptotic sensitivity might contribute to the increased vulnerability of the young brain to radiation. Postnatal day 1 (P1) to P30 mice were treated with 0-16 Gy whole-body X-irradiation. Apoptotic cells were identified and quantified up to 48 h later using the TdT-UTP nick end-labelling method (TUNEL) and immunohistochemistry for activated caspase-3. The number of neuron-specific nuclear protein (NeuN)-positive and -negative cells were also counted to measure neuronal and non-neuronal cell loss. Significantly greater TUNEL labelling occurred in the cortex of irradiated P1 animals relative to the other age groups, but there was no difference among the P7, P14 and P30 groups. Irradiation decreased the %NeuN-positive cells in the mice irradiated on P1, whereas in P14 animals, irradiation led to an increase in the %NeuN-positive cells. These data demonstrate that neocortical neurons of very young mice are more susceptible to radiation-induced apoptosis. However, this sensitivity decreases rapidly after birth. By P14, acute cell loss due to radiation occurs primarily in non-neuronal populations.

Sequential delivery of interferon-alpha gene and DCs to intracranial gliomas promotes an effective antitumor response.

Effective presentation of tumor antigens by dendritic cells (DCs) is considered to be essential for the induction of antitumor T-cell responses. Apoptotic and necrotic tumors have been noted to be a robust antigen source for DCs. Because glioma cells undergo apoptosis after transfection with the type I interferon (IFN) gene and type I IFNs promote the stimulatory activity of DCs, we hypothesized that transfection of glioma cells with type I IFN genes and provision of DCs would promote particularly effective antitumor activity by both facilitating apoptosis of glioma cells and the presentation of the glioma antigens, thereby inducing specific immune responses against glioma cells. We have previously reported the proof of this hypothesis in vitro and in a subcutaneous tumor model. Here we report an extension of this approach in intracranial (i.c.) gliomas using adenoviral IFN-alpha (Ad-IFN-alpha) vector. Mice bearing day-5 i.c. GL261 glioma received sequential intratumoral (i.t.) delivery of Ad-IFN-alpha and bone marrow-derived syngeneic DCs. This treatment prolonged survival in that nine of 17 animals survived long term (> 60 days versus 0 of 10 control animals). Specific CTL activity was demonstrated following this regimen in the cervical lymph nodes, and the therapeutic efficacy was dependent upon CD8+ cells. Furthermore, these animals were protected against subsequent re-challenge with GL261 gliomas. DCs injected i.t. survived in the tumor and migrated into cervical lymph node. In vitro migration assays revealed the ability of DCs to migrate toward the tumor, suggesting that i.t. injected DCs migrate through the glioma. Taken together, this combination of gene therapy and cellular immunotherapy may be an effective future strategy for treating human gliomas.

Age-related changes in intracranial pressure in rabbits with uncorrected familial coronal suture synostosis.

OBJECTIVE: Chronic, elevated intracranial pressure (ICP) in craniosynostotic infants may result in ocular and neurocapsular problems; however, not all infants exhibit elevated ICP. Clinical ICP studies are further confounded by small and heterogeneic samples, multiple-suture involvement, and varying surgical management protocols. The present study was designed to describe longitudinal changes in ICP in a large, homogenous sample of rabbits with uncorrected familial, nonsyndromic coronal suture synostosis. METHODS: Ninety-one rabbits were divided into four groups: (1) normal rabbits (n = 28), (2) rabbits with delayed-onset coronal suture synostosis (DOCS; n = 25), (3) rabbits with unilateral coronal suture synostosis (UCS; n = 12), and (4) rabbits with bilateral coronal suture synostosis (BCS; n = 26). ICP was measured at 24 and 42 days of age using a Codman epidural microtransducer. RESULTS: Rabbits with BCS had a significantly (p < .05) higher mean ICP at 25 days of age than rabbits in the other three groups by approximately 146%. However, by 42 days of age, mean ICP in normal control rabbits and rabbits with DOCS was significantly (p < .01) increased compared with their mean ICP values seen at 25 days of age, while mean ICP in BCS rabbits significantly (p < .01) decreased (by 32%) over the same time period. ICP in rabbits with UCS was between that seen in normal control rabbits and rabbits with BCS and did not significantly (p > .05) change over time. CONCLUSIONS: These findings suggest that the degree of suture involvement may be related to early increases in ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are discussed.

Increased intracranial pressure after coronal suturectomy in craniosynostotic rabbits.

It has been suggested that the complications associated with intracranial hypertension in craniosynostotic infants may be managed with surgical release of the synostosed sutures. However, both postoperative increases and decreases in intracranial pressure (ICP) have been reported in heterogeneous samples of infants with syndromic and nonsyndromic craniosynostoses. The present study was designed to describe longitudinal changes in ICP in a homogeneous sample of rabbits with uncorrected and corrected familial coronal suture synostosis and compare them with age-matched normal control rabbits. Fifty-three rabbits were divided into three groups: normal rabbits (n = 28), rabbits with uncorrected bilateral coronal suture synostosis (n = 9), and rabbits with bilateral coronal suture synostosis with coronal suturectomy at 25 days of age (n = 16). ICP was measured at 25 and 42 days of age using a Codman epidural microtransducer. Results revealed that rabbits with uncorrected craniosynostosis had significantly (P < 0.05) higher ICP at 25 days of age than normal control rabbits by approximately 86%. However, by 42 days of age, ICP in normal rabbits increased by 75%, whereas ICP in rabbits with uncorrected craniosynostosis decreased by 69% over the same time. Synostotic rabbits with coronal suturectomy showed a 50% decrease in ICP immediately after surgical release and then followed the normal, age-related ICP pattern, which significantly increased by 75% at 42 days of age. Results suggest that, in the rabbit model, the postsuturectomy rise in ICP may simply be normal, age-related changes, although a longer follow-up will be needed to determine the recurrence of pathological ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are also discussed.

A rabbit model of human familial, nonsyndromic unicoronal suture synostosis. II. Intracranial contents, intracranial volume, and intracranial pressure.

This two-part study reviews data from a recently developed colony of New Zealand white rabbits with familial, nonsyndromic unilateral coronal suture synostosis, and this second part presents neuropathological findings and age-related changes in intracranial volume (ICV) and intracranial pressure (ICP) in 106 normal rabbits and 56 craniosynostotic rabbits from this colony. Brain morphology and anteroposterior length were described in 44 rabbit fetuses and perinates (27 normal; 17 synostosed). Middle meningeal artery patterns were qualitatively assessed from 2-D PCC MRI VENC scans and endocranial tracings from 15, 126-day-old rabbits (8 normal, 7 rabbits with unicoronal synostosis). Brain metabolism was evaluated by assessing 18F-FDG uptake with high-resolution PET scanning in 7, 25-day-old rabbits (3 normal, 4 with unicoronal or bicoronal synostosis). Intracranial contents and ICV were assessed using 3-D CT scanning of the skulls of 30 rabbits (20 normal,10 with unicoronal synostosis) at 42 and 126 days of age. Serial ICP data were collected from 66 rabbits (49 normal; 17 with unicoronal synostosis) at 25 and 42 days of age. ICP was assessed in the epidural space using a Codman NeuroMonitor microsensor transducer. Results revealed that cerebral cortex morphology was similar between normal and synostosed fetuses around the time of synostosis. Significantly (P<0.05) decreased A-P cerebral hemisphere growth rates and asymmetrical cortical remodeling were noted with increasing age in synostotic rabbits. In addition, rabbits with unicoronal suture synostosis exhibited asymmetrical middle meningeal artery patterns, decreased and asymmetrical brain metabolism, a "beaten-copper" intracranial appearance, significantly (P<0.05) decreased ICV, and significantly (P<0.01) elevated ICP compared with normal control rabbits. The advantages and disadvantages of these rabbits as a model for human familial, nonsyndromic unicoronal suture synostosis are discussed, especially in light of recent clinical neuropathological, ICV, and ICP findings recorded in human craniosynostotic studies.