Differential effects of AMPA receptor activation on survival and neurite integrity during neuronal development

While neuronal cultures are an established model for analyzing excitotoxic brain injury in the adult, in vitro systems have not been extensively employed to study how developing neurons respond to levels of excitatory compounds that are lethal to mature neurons. Recently, we reported that the in vivo differentiation programs of cerebellar granule cells (CGNs) are recapitulated in purified CGN cultures [Manzini M.C., Ward M.S., Zhang Q., Lieberman M.D., Mason C.A. (2006) The stop-signal revised: immature cerebellar granule neurons in the external germinal layer arrest pontine mossy fiber growth. J. Neurosci. 26:6040-6051]. Here, we have used this model system to compare the response of immature and mature neurons to excitotoxic compounds. We found that immature CGNs are less sensitive to AMPA receptor (AMPA-R) activation than mature cells and that levels of AMPA-R expression on the plasma membrane are critical in regulating the balance between death and survival during maturation of these neurons. However, the majority of immature cells that survive excitotoxic treatment bear a degenerating neurite, suggesting that AMPA-R activation can still cause damage in the absence of cell death.

Genetic counselling following paternal therapeutic irradiation

We discuss a patient who received adjuvant radiotherapy for stage I seminoma. He was advised to avoid conception for 6 months following treatment. However, his partner became pregnant only shortly after he completed his radiotherapy (i.e. with sperm that had been irradiated). We estimated the dose received by the remaining testis as 30 cGy. Here, we review the information available to advise patients on the risks to the fetus from paternal preconception irradiation. For the population, a doubling dose for hereditary effects of 1 Gy has recently been reaffirmed (United Nations Scientific Committee on the Effects of Atomic Radiation 2001). However, a range of animal studies suggest conception with postmeiotic sperm carries a greater risk of genetic damage than conception with sperm derived from irradiated stem cells. We have attempted to quantify the risks in this particular case. Lead shielding of the testes may reduce radiation received from the primary beam, but internal scatter still produces a risk. In male patients who are potentially fertile, the best advice remains to delay conception after radiotherapy for as long as 6 months. Our case illustrates the need to reinforce such advice.

Cell type-specific interleukin-1beta signaling in the CNS

Interleukin-1beta (IL-1beta) is a potent and pleiotropic inflammatory cytokine that is highly produced in the CNS under conditions of damage, disease, or stress. This cytokine acts on CNS glia to effect inflammatory responses, mediated in part via activation of the nuclear factor-kappaB (NF-kappaB) transcription factor, and consequent induction of numerous cytokines. Neurons as well as astrocytes in the hippocampus also express the type 1 IL-1 receptor, indicating that this cytokine can influence neuronal function directly, yet IL-1beta does not induce production of cytokines in neurons as it does in glia. In contrast, IL-1beta regulates synaptic function of hippocampal neurons. Here we demonstrate that different signaling pathways mediate IL-1beta actions in neurons as compared with astrocytes. IL-1beta activates the p38 mitogen-activated protein kinase (MAPK) signaling pathway and induces the activation of CREB in hippocampal neurons, in contrast to the activation of NF-kappaB in hippocampal astrocytes, demonstrating cell type-specific signaling responses to IL-1 in the brain and yielding distinct functional responses.

Surgical caseload and outcomes for women with invasive breast cancer treated in Western Australia

We have assessed the outcomes for all women diagnosed with invasive breast cancer in Western Australia during 1989, 1994 and 1999, and compared the results for surgeons who treat 20 or more cases per year with those of surgeons who treat less. Women treated by high caseload surgeons were more likely to retain their breast (53.3% vs. 36.7%, p<0.001), have adjuvant radiotherapy (50.0% vs. 30.6%, p<0.001), and be alive after 4 years (1989, 86% vs. 82%; 1994, 89% vs. 84%; 1999, 90% vs. 79%, HR 0.71, p=0.03). Adjusting for age and year of diagnosis, women were not more likely to be treated with adjuvant chemotherapy (29.2% vs. 20.9%, p=0.28). In 1989 35% of women were treated by high caseload surgeons. By 1999 this had risen to 82%. The results confirm that women treated by high caseload surgeons have better outcomes.

Functional similarities and differences of AMPA and kainate receptors expressed by cultured rat sensory neurons

Dorsal root ganglion neurons express functional AMPA and kainate receptors near their central terminals. Activation of these receptors causes a decrease in glutamate release during action potential evoked synaptic transmission. Due to differences in kinetic properties and expression patterns of these two families of glutamate receptors in subpopulations of sensory neurons, AMPA and kainate receptors are expected to function differently. We used embryonic dorsal root ganglion (DRG) neurons maintained in culture to compare functional properties of kainate and AMPA receptors. Most DRG neurons in culture expressed kainate receptors and about half also expressed AMPA receptors. Most AMPA and kainate receptor-expressing DRG neurons were sensitive to capsaicin, suggesting involvement of these glutamate receptors in nociception. When activated by kainate, AMPA receptors were capable of driving a sustained train of action potentials while kainate receptors tended to activate action potential firing more transiently. Glutamate elicited more action potentials and a larger steady-state depolarization in neurons expressing both AMPA and kainate receptors than in neurons expressing only kainate receptors. Adding to their more potent activation properties, AMPA receptors recovered from desensitization much more quickly than kainate receptors. Activation of presynaptic receptors by low concentrations of kainate, but not ATPA, caused a tetrodotoxin-sensitive increase in the frequency of spontaneous EPSCs recorded in dorsal horn neurons. By recording synaptic pairs of DRG and dorsal horn neurons, we found that activation of presynaptic kainate and AMPA receptors decreased evoked glutamate release from terminals of DRG neurons in culture. Our data suggest that the endogenous ligand, glutamate, will cause a different physiological impact when activating these two types of non-NMDA glutamate receptors at central or peripheral nerve endings of sensory neurons.

Multicentre analysis of treatment planning information: Technical requirements, possible applications and a proposal

Digital data from 3-D treatment planning computers is generally used for patient planning and then never considered again. However, such data contains enormous quantities of information regarding patient geometries, tissue outlining, treatment approaches and dose distributions. Were such data accessible from planning systems from multiple manufacturers, there would be substantial opportunities for undertaking quality assurance of radiotherapy clinical trials, prospective assessment of trial outcomes and basic treatment planning research and development. The technicalities of data exchange between planning systems are outlined, and previous attempts at producing systems capable of viewing and/or manipulating imaging and radiotherapy digital data reviewed. Development of a software system for enhancing the quality of Australasian clinical trials is proposed.

A randomised trial of single-dose radiotherapy to prevent procedure tract metastasis by malignant mesothelioma

A single 9-MeV electron treatment, following invasive thoracic procedures in patients with malignant pleural mesothelioma, was examined. In all, 58 sites were randomised to prophylactic radiotherapy or not. There was no statistically significant difference in tract metastasis. A single 10-Gy treatment with 9-MeV electrons appears ineffective.

A prospective trial of short-fractionation radiotherapy for the palliation of liver metastases

The purpose of this study was to prospectively examine the effectiveness and tolerability of a simple radiotherapy technique for the palliation of symptomatic liver metastases. Twenty-eight patients with symptomatic liver metastases were enrolled from seven centres, and received targeted (partial or whole) liver irradiation consisting of 10 Gy in two fractions over 2 days. Symptoms at baseline were hepatic pain (27 patients), abdominal distension (19), night sweats (12), nausea (18) and vomiting (eight). Twenty-two patients (76%) had failed previous treatment with chemotherapy, hormonal therapy and/or high-dose steroids. Symptoms and potential toxicities were prospectively assessed at the time of treatment, then 2, 6 and 10 weeks later. Individual symptom response rates were 53-66% at 2 weeks. Partial or complete global symptomatic responses were noted in 15 patients (54%) overall. The treatment was well tolerated with two patients (7%) experiencing grade 3 toxicity (one vomiting and one diarrhoea); however, four patients reported temporary worsening of pain shortly after treatment. This simple and well-tolerated treatment achieves useful palliation.

Functional expression of AMPA receptors on central terminals of rat dorsal root ganglion neurons and presynaptic inhibition of glutamate release

No direct evidence has been found for expression of functional AMPA receptors by dorsal root ganglion neurons despite immunocytochemical evidence suggesting they are present. Here we report evidence for expression of functional AMPA receptors by a subpopulation of dorsal root ganglion neurons. The AMPA receptors are most prominently located near central terminals of primary afferent fibers. AMPA and kainate receptors were detected by recording receptor-mediated depolarization of the central terminals under selective pharmacological conditions. We demonstrate that activation of presynaptic AMPA receptors by exogenous agonists causes inhibition of glutamate release from the terminals, possibly via primary afferent depolarization (PAD). These results challenge the traditional view that GABA and GABA(A) receptors exclusively mediate PAD, and indicate that PAD is also mediated by glutamate acting on presynaptically localized AMPA and kainate receptors.

System validation and work practice efficiency gains of a new localization method for stereotactic radiotherapy

The increased procedural demands of stereotactic localization techniques when compared with conventional treatment practices reduces machine efficiency, an outcome likely to be greatly magnified by the introduction of fractionation to stereotactic techniques. Currently in Australia and New Zealand there are no guidelines for the definition of efficiency. We sought to devise a system to simultaneously validate the accuracy and efficiency of the technique. The frameless relocation methods employed in the Medtronic Sofamor Danek (MSD) stereotactic radiotherapy (SRT) system were studied in the clinical setting. Accuracy has been determined according to the accumulation of errors throughout the planning and treatment process. The clinical demands of the system (staffing and resources) were analysed relative to conventional treatment approaches. Timing studies indicate a mean time of 19.7 min for treatment of a daily SRT fraction (4-5 arcs, single isocentre). Cost and staffing requirements are similar to those for conventional radiotherapy. It is concluded that with the system used, SRT is efficient for routine clinical implementation, with the level of efficiency increasing with increasing patient numbers. It is recommended that a common acceptance standard be developed to allow cross-institutional comparison of the clinical efficiency of new treatment techniques.

Introduction and implementation of the basic treatment equivalent in a Varian-based department

The increasing popularity of 3-D planning leads to procedural alterations as both workload and resource utilization increase. Although the complexity of the techniques has increased (as well as the set-up and treatment times), the workload statistics must still include the number of fields treated. It is commonly known that machine statistics of fields treated per day do not accurately represent workload because there are major differences between techniques. A mantle treatment technique and an opposed spine technique both have (statistically) two fields, although the set-up requirements and treatment times are very different. A basic treatment equivalent (BTE) formula was reported in early 1999 by Delaney et al. and incorporates a large number of variables inherent in patient treatment. The formula considers different factors that affect overall treatment time, and aims to represent a more accurate treatment time indicator. The aim of introducing the BTE into the Department of Radiation Oncology at Sir Charles Gairdner Hospital was to create a more accurate scheduling system and even out workloads on all treatment units. Therefore the BTE formula was used to assess accuracy of treatment times in order to determine if the values could be relied upon as accurate time indicators. Patients undergoing a variety of treatment techniques were timed for the duration of their treatment procedure, and their treatment times compared to the time estimated using the BTE formula. A few minor alterations were made to the equation for treatment units with multi-leaf collimation (MLC). A trial conducted at Sir Charles Gairdner Hospital found that, using the BTE formula (with a few modifications required for the MLC treatment units), of 60 patients timed for the duration of their set-up and treatment, 85% of values were in the range of +/- 3 min, and 95% were in the range of +/- 5 min of the estimated times. Through the routine use of the BTE equation a more sensitive indication of treatment machine workload can be found. Advantages such as: (i) a more accurate measure of treatment workload (for comparison with other departments) and (ii) increased scheduling accuracy will succeed over the currently accepted system of fields per hour.

A phase III double-blind randomised study of rectal sucralfate suspension in the prevention of acute radiation proctitis

BACKGROUND AND PURPOSE

A limited number of studies have suggested that oral sucralfate reduces the acute and late gastro-intestinal side-effects of pelvic radiotherapy and sucralfate enemas ameliorate symptoms of chronic proctitis. Sucralfate may act via local bFGF at the mucosal level in promoting angiogenesis and reducing epithelial associated microvascular injury. This multi-institutional study was designed to test the hypothesis that sucralfate given as an enema would have a significant protective effect against acute radiation induced rectal injury by direct application to the mucosa.

MATERIALS AND METHODS

Eighty-six patients having radiotherapy for localised carcinoma of the prostate were randomised in a double-blind placebo-controlled study to receive either 15 ml of placebo suspension or 3 g of sucralfate in 15 ml suspension, given as a once daily enema during and for 2 weeks following radiotherapy. Assessment was based on the EORTC/RTOG acute toxicity criteria and a patient self-assessment diary.

RESULTS

There was no significant difference between placebo and sucralfate for peak incidences of EORTC/RTOG proctitis. For the placebo and sucralfate arms 95 and 88% (difference 7 +/- 11%) suffered some degree of proctitis, with 71 and 61% (difference 10 +/- 19%) reaching grade 2, respectively. The median period to onset of grade 2 proctitis was 33.5 and 36 days, with the median duration being 9.5 and 15 days, respectively, again these difference being non-significant. Thirty-five and 37% of patients rated the effect of radiotherapy on bowel habit as 'a lot' with a moderate or severe effect on normal daily living in 52 and 49%, respectively.

CONCLUSION

This study suggests that sucralfate given as a once daily enema does not substantially reduce the incidence of symptoms associated with acute radiation proctitis and its routine clinical use cannot be recommended. This cohort of patients will be followed to determine if any difference develops in relation to late toxicity.

A combined modality approach to the management of oesophageal cancer

This study aims to update the experience of multimodality approaches in the management of oesophageal cancer that have been adopted in several Australian and New Zealand hospitals. Between 1984 and 1985, 92 patients received pre-operative radiotherapy (30-36 Gy over 3 weeks) and one of two chemotherapy regimes (one or two courses of i.v. cisplatin 80 mg/m2 plus a 4-5 day continuous i.v. of fluorouracil 5-800 mg/m2/day) concurrently prior to surgery. Eighty-two patients (89%) underwent resection as planned. Operative specimens were microscopically free of residual tumour in 18 patients. Eight patients (9%) had treatment-related deaths: seven from surgery and one due to pre-operative chemoradiation. The Kaplan-Meier 5-year cause-specific survival estimates were 32.9 +/- 7.8% for the 58 patients with squamous cancer and 0% for the 32 with adenocarcinoma. Complete pathological response to the pre-operative regime was more common in females and was associated with a survival advantage. Five-year cause-specific survival expectation in patients who experienced a complete pathological response was 71.5 +/- 12.4%, whereas it was only 15.9 +/- 5.6% in patients who had residual cancer in their surgical specimens. Although less toxic the pre-operative regime utilizing only one cycle of chemotherapy was no less efficacious either in producing a complete pathological response or in terms of survival expectation. This uncontrolled pilot study has produced encouraging long-term results, especially for patients with squamous carcinoma that experienced a complete response to pre-operative synchronous chemoradiotherapy. A randomized controlled study comparing surgery alone with (one cycle) chemoradiation followed by surgery is now underway.

Factors influencing outcome following radio-chemotherapy for oesophageal cancer. The Trans Tasman Radiation Oncology Group (TROG)

BACKGROUND AND PURPOSES

To define new directions, the Trans Tasman Radiation Oncology Group (TROG) has conducted a detailed analysis of its unrandomised experience with radio-chemotherapy in oesophageal cancer.

METHODS AND PATIENTS

Since 1984, 373 patients with oesophageal cancer have been treated on three prospective, but unrandomised, protocols involving radiation with concurrent cisplatin and infusional fluorouracil. Centres in Australia and New Zealand have contributed patients. Reasons for case selection have been examined in detail and prognostic models have been examined in the light of biases exposed.

RESULTS

Cause specific survival in 92 patients treated pre-operatively with 35 Gy, infusional fluorouracil and cisplatin was 25.5 +/- 6.0% at 5 years and similar to the 5 year expectations of 169 patients treated with 60 Gy and two courses of the same chemotherapy (23.8 +/- 4.7%). Analysis of failure in these groups suggests that local relapse precedes the development of metastases and competes as a cause for ultimate failure. Although patients treated surgically were less likely to relapse locally, survival was no better because more developed metastases. Some of the 112 patients treated "palliatively" with 30-35 Gy concurrent with chemotherapy without surgery have become long-term survivors with 5 year survival figure in this group 7.7 +/- 3.4%. Apart from variables related to disease stage and performance status at presentation, tumour site emerged as a strong predictor of outcome. Prognosis worsens the nearer the tumour is to the stomach. In addition, indications of a radiation dose response relationship emerged.

CONCLUSIONS

Concurrent radio-chemotherapy protocols can improve outcome in patients fit enough to tolerate these approaches. New strategies remain necessary, however.

Factors influencing the degree of erythematous skin reactions in humans

Dose-response relationships have been studied using an ordinal visual scale and reflectance spectrophotometry data from 123 treatment sites on 110 patients treated with 10 dose fractions over 12-14 days. Dose rates varied between 3 and 240 Gy/h and total doses of between 25 and 41 Gy were given using teletherapy apparatus. We found qualitative scoring of erythematous skin reactions to be subject to considerable inter- and intra-observer variation. Reflectance spectrophotometry provided more reproducible information, some of which was undetectable by naked eye. Baseline erythema readings were significantly higher in male patients and at anatomical sites of previous heavy UV exposure. In addition, a pronounced decline in erythema readings during the second week of therapy and 'reciprocal vicinity' (abscopal) effects adjacent to the field, undetected by the eye, were observed in a subset of patients. Meaningful dose-response relationships could be derived only from reflectance data with peak change from the pretreatment baseline measure providing the best discrimination. Peak erythema measures following treatment were found to depend on the age and gender of the patient as well as the treatment site and its baseline erythema measurement. This was independent of the total dose administered or the instantaneous dose rate at which it was delivered. The rate of erythema development was also dose rate dependent but only weakly dependent on the biological dose intensity (Gy equiv./day) of the treatment course. The data raise the question of whether irradiation-induced erythema is exclusively a secondary phenomenon occurring as a result of basal cell killing. The short repair half time value of 0.06 h obtained by direct analysis is perplexing and may reflect a dose rate-dependent physiological vasodilatory response to irradiation and/or a multi-component cellular repair process.

Bacillus Calmette-Guérin complications in children born to HIV-1-infected women with a review of the literature

OBJECTIVE

To compare the risk of complications following Bacillus Calmette-Guérin (BCG) vaccination among children by maternal and infant HIV-1 infection status as part of an investigation of an outbreak of BCG complications.

METHODS

A nonconcurrent cohort study of BCG complications among 125 infants born to HIV-1 seropositive and 166 infants born to HIV-1 seronegative mothers was conducted in Cité Soleil, Haiti. Infants were examined at regular intervals until 15 months of age, and complications from BCG were documented. An investigation of BCG vaccination practices was conducted.

RESULTS

Mild or moderate complications occurred among 16 of 166 (9.6%) infants born to HIV-1 seronegative mothers compared with 4 of 13 HIV-1-infected infants (30.8%, P = .04) and 10 of 75 (13.3%, P = .39) uninfected infants born to HIV-1-infected mothers. No serious complications were noted. The outbreak of complications was associated with administration of 2.0 to 2.5 times the recommended dose of BCG vaccine.

CONCLUSIONS

This and five other cohort studies indicate that there may be a small increased risk of complications following BCG vaccination among HIV-1-infected children, but the reactions are usually mild and the risk does not outweigh the benefits of BCG vaccination in populations at high risk of tuberculosis during infancy and childhood.

Prevalence of HIV-1 DNA and p24 antigen in breast milk and correlation with maternal factors

Breast milk specimens from human immunodeficiency virus type 1 (HIV-1)-seropositive and HIV-1-seronegative women were examined for the presence of HIV-1 p24 antigen by the antigen capture method and for viral DNA using the polymerase chain reaction. HIV-1 DNA was present in 70% of milk specimens collected from 47 HIV-seropositive women 0-4 days after delivery and in approximately 50% of specimens collected 6 and 12 months postpartum. p24 antigen, present in 24% of milk specimens collected from 37 seropositive women within the first 4 days postpartum, was not detected in any of the subsequent specimens. The presence of HIV-1 DNA or p24 antigen in milk was not significantly associated with maternal CD4 lymphocyte count, beta 2-microglobulin level, or fulfillment of the AIDS clinical case definition. Although the correlation of either HIV-1 proviral DNA or p24 antigen with the presence of infectious virus is not known, these data indicate the need for additional studies examining the role of breastfeeding in maternal-infant transmission of HIV-1.

Phase I/II study of concurrent weekly carboplatin and radiation therapy in advanced head and neck cancer

Thirty-two patients with locally advanced head and neck cancer have been treated with concurrent weekly carboplatin and conventional radiation therapy (RT) (2 Gy fractions 4-5 days/week to a total dose of 64-70 Gy over 7-8 weeks) in a Phase I/II study. Carboplatin was administered weekly during RT at doses of 75-150 mg/m2/wk as a 1-hour infusion. The maximum tolerated dose of carboplatin was 130 mg/m2/wk, with myelosuppression, predominantly neutropenia, being dose limiting. Other systemic toxicities were insignificant and no overlapping toxicity was evident. Ultimate locoregional control and survival probabilities were disappointing. It is suggested that either further studies using radiation and carboplatin at the dose 130 mg/m2/wk, or variations on dose and scheduling be performed prior to the instigation of Phase III studies.

Pelvic radiotherapy with concurrent 5-fluorouracil modulated by leucovorin for rectal cancer: a phase II study

Combined modality treatment for cancer of the rectum has been shown to reduce recurrences and improve overall survival. We wished to find out if we could safely give concurrent radiotherapy and 5-fluorouracil (5-FU) modulated by leucovorin (LV) in 3 settings: pre-operatively, adjuvantly and in recurrent disease. A total of 39 patients were treated, 11 preoperatively, 17 adjuvantly and 11 with recurrent disease. There were 26 males and 13 females with a median age of 64 years. The median radiotherapy (RT) dose was 45 Gy/25 fractions/1.8 Gy per fraction (range 25-63 Gy). Chemotherapy consisted of LV 80 mg/m2 i.v. infusion over 1.5 hours followed by 5-FU 400 mg/m2 i.v. bolus, both given once a week. The median number of cycles was 8 (range 3-12). Diarrhoea was the main toxicity, and was encountered in 30 patients (77%): grade 1 in 3 (8%), grade 2 in 12 (30%), grade 3 in 11 (28%), and grade 4 in 4 (10%). This required 18 (46%) patients to have modifications to their RT (20% had breaks and 26% ceased at doses < 45 Gy). Nine patients (23%) had modifications in the chemotherapy (10% had breaks and 13% received < 6 cycles). Encouraging responses were seen in the preoperative setting. Concurrent RT and 5-FU/LV, as given in this schedule, results in an unacceptable incidence of diarrhoea, limiting both the total dose of RT and chemotherapy that can be delivered, particularly in patients who have had previous surgery.

Treatment and planning decisions in non-small cell carcinoma of the lung: an Australasian patterns of practice study

Fourteen practising radiation oncologists were surveyed to assess their treatment and planning habits utilizing six sample cases of non-small cell carcinoma of the lung. Respondents were first given a general questionnaire, designed to evaluate their theoretical treatment and planning recommendations based on various tumour and patient related variables. Respondents then undertook a practical planning exercise utilizing planning CT and simulator radiographs for each of the six sample cases. Each case was accompanied by a brief history and report outlining specific tumour stage and non-stage related variables. The practical planning exercise was repeated on the second day of the survey utilizing different non-stage related variables but identical radiology and stage-related information. This design enabled firstly, a comparison of clinicians' intended policy and planning methods with actual policy and planning decisions, and secondly, an assessment of intra-clinician variability in decision making and planning practice. Good agreement was evident among clinicians with respect to general, non-case specific treatment policies; however, very significant variation occurred at an inter- and intra-clinician level and involved the entire treatment and planning process for individual cases. Despite identical treatment intent across identical radiological case pairings, clinicians chose widely differing margins and target volumes in their planning exercise. Treatment intent appeared to be influenced more by non-stage related variables rather than stage related information and radiological appearances per se. We have shown that experienced radiation oncologists do not adhere to stated case selection criteria and show inconsistencies in their treatment planning for non-small cell carcinoma of the lung.