Context controls the timing of responses to an alcohol-predictive conditioned stimulus

Context can influence the number of responses elicited by a discrete, appetitive conditioned stimulus (CS) but can context control when a CS elicits a response? To test this fundamental question, we gave male, Long-Evans rats Pavlovian conditioning sessions in which the same auditory conditioned stimulus (CS, 30 s, 15 trials/session) was presented in 2 different physical contexts on alternating days, according to a within-subjects design. In one context, called the early context, alcohol (15 % ethanol, 0.2 ml/trial) was delivered from the onset of the 5^th second until the termination of the 10^th second of the 30 s CS. In the second late context, alcohol was delivered from the onset of the 25^th second until the termination of the 30^th second of the same CS. In a comparison of the last session of training, the probability of making a conditioned response during the first four seconds of the CS was significantly higher in the early context than in the late context. This result shows that context can signal when an unconditioned stimulus occurs in relation to a CS and highlights a role for context in controlling precisely timed alcohol-seeking responses.

Consolidative mediastinal irradiation of malignant lymphoma using active scanning proton beams: clinical outcome and dosimetric comparison

PURPOSE

Current research approaches in lymphoma focus on reduction of therapy-associated long-term side effects. Especially in mediastinal lymphoma, proton beam radiotherapy (PT) may be a promising approach for reducing the dose to organs at risk (OAR).

PATIENTS

In total, 20 patients were irradiated with active scanning PT at Heidelberg Ion Beam Therapy Center (HIT) between September 2014 and February 2017. For comparative analysis, additional photon irradiation plans with helical intensity-modulated radiotherapy (IMRT) were calculated and quantitative and qualitative dose evaluations were made for both treatment modalities. Toxicity and survival outcomes were evaluated.

RESULTS

Clinical target volume coverage was comparable in both treatment modalities and did not significantly differ between IMRT and PT. Nevertheless, PT showed superiority regarding the homogeneity index (HI_PT = 1.041 vs. HI_IMRT = 1.075, p < 0.001). For all OAR, PT showed significantly higher dose reductions compared with IMRT. In particular, the dose to the heart was reduced in PT (absolute dose reduction of D_mean of 3.3 Gy [all patients] and 4.2 Gy [patients with pericardial involvement]). Likewise, the subgroup analysis of female patients, who were expected to receive higher doses to the breast, showed a higher dose reduction in D_mean of 1.2 Gy (right side) and 2.2 Gy (left side). After a median follow-up of 32 months (range 21-48 months), local and distant progression free survival (LPFS and DPFS) were 95.5% and 95.0%, respectively. Radiotherapy was tolerated well with only mild (grade 1-2) radiation-induced acute and chronic side effects.

CONCLUSION

A significant reduction in the dose to the surrounding OAR was achieved with PT compared with photon irradiation, without compromising target volume coverage. Dosimetric advantages may have the potential to translate into a reduction of long-term radiation-induced toxicity in young patients with malignant lymphoma of the mediastinum.

4DMRI-based investigation on the interplay effect for pencil beam scanning proton therapy of pancreatic cancer patients

BACKGROUND

Time-resolved volumetric magnetic resonance imaging (4DMRI) offers the potential to analyze 3D motion with high soft-tissue contrast without additional imaging dose. We use 4DMRI to investigate the interplay effect for pencil beam scanning (PBS) proton therapy of pancreatic cancer and to quantify the dependency of residual interplay effects on the number of treatment fractions.

METHODS

Based on repeated 4DMRI datasets for nine pancreatic cancer patients, synthetic 4DCTs were generated by warping static 3DCTs with 4DMRI deformation vector fields. 4D dose calculations for scanned proton therapy were performed to quantify the interplay effect by CTV coverage (v95) and dose homogeneity (d5/d95) for incrementally up to 28 fractions. The interplay effect was further correlated to CTV motion characteristics. For quality assurance, volume and mass conservation were evaluated by Jacobian determinants and volume-density comparisons.

RESULTS

For the underlying patient cohort with CTV motion amplitudes < 15 mm, we observed significant correlations between CTV motion amplitudes and both the length of breathing cycles and the interplay effect. For individual fractions, tumor underdosage down to v95 = 70% was observed with pronounced dose heterogeneity (d5/d95 = 1.3). For full × 28 fractionated treatments, we observed a mitigation of the interplay effect with increasing fraction numbers. On average, after seven fractions, a CTV coverage with 95-107% of the prescribed dose was reached with sufficient dose homogeneity. For organs at risk, no significant differences were found between the static and accumulated dose plans for 28 fractions.

CONCLUSION

Intrafractional organ motion exhibits a large interplay effect for PBS proton therapy of pancreatic cancer. The interplay effect correlates with CTV motion, but can be mitigated efficiently by fractionation, mainly due to different breathing starting phases in fractionated treatments. For hypofractionated treatments, a further restriction of motion may be required. Repeated 4DMRI measurements are a viable tool for pre- and post-treatment evaluations of the interplay effect.

Significance of intra-fractional motion for pancreatic patients treated with charged particles

Background

Uncertainties associated with the delivery of treatment to moving organs might compromise the accuracy of treatment. This study explores the impact of intra-fractional anatomical changes in pancreatic patients treated with charged particles delivered using a scanning beam. The aim of this paper is to define the potential source of uncertainties, quantify their effect, and to define clinically feasible strategies to reduce them.

Methods

The study included 14 patients treated at our facility with charged particles (protons or 12C) using intensity modulated particle therapy (IMPT). Treatment plans were optimized using the Treatment Planning System (TPS) Syngo® RT Planning. The pre-treatment dose distribution under motion (4D) was simulated using the TPS TRiP4D and the dose delivered for some of the treatment fractions was reconstructed. The volume receiving at least 95% of the prescribed dose (V95CTV) and the target dose homogeneity were evaluated. The results from the 4D dose calculations were compared with dose distributions in the static case and its variation correlated with the internal motion amplitude and plan modulation, through the Pearson correlation coefficient, as well the significant p-value. The concept of the modulation index (MI) was introduced to assess the degree of modulation of IMPT plans, through the quantification of intensity gradients between neighboring pencil beams.

Results

The induced breathing motion together with dynamic beam delivery results in an interplay effect, which affects the homogeneity and target coverage of the dose distribution. This effect is stronger (∆V_95CTV > 10%) for patients with tumor motion amplitude above 5 mm and a highly modulated dose distribution between and within fields. The MI combined with the internal motion amplitude is shown to correlate with the target dose degradation and a lack of plan robustness against range and positioning uncertainties.

Conclusions

Under internal motion the use of inhomogeneous plans results in a decrease in the dose homogeneity and target coverage of dose distributions in comparison to the static case. Plan robustness can be improved by using multiple beams and avoiding beam entrance directions susceptible to density changes. 4D dose calculations support the selection of the most suitable plan for the specific patient’s anatomy.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1060-8) contains supplementary material, which is available to authorized users.

Next generation multi-scale biophysical characterization of high precision cancer particle radiotherapy using clinical proton, helium-, carbon- and oxygen ion beams

The growing number of particle therapy facilities worldwide landmarks a novel era of precision oncology. Implementation of robust biophysical readouts is urgently needed to assess the efficacy of different radiation qualities. This is the first report on biophysical evaluation of Monte Carlo simulated predictive models of prescribed dose for four particle qualities i.e., proton, helium-, carbon- or oxygen ions using raster-scanning technology and clinical therapy settings at HIT. A high level of agreement was found between the in silico simulations, the physical dosimetry and the clonogenic tumor cell survival. The cell fluorescence ion track hybrid detector (Cell-Fit-HD) technology was employed to detect particle traverse per cell nucleus. Across a panel of radiobiological surrogates studied such as late ROS accumulation and apoptosis (caspase 3/7 activation), the relative biological effectiveness (RBE) chiefly correlated with the radiation species-specific spatio-temporal pattern of DNA double strand break (DSB) formation and repair kinetic. The size and the number of residual nuclear γ-H2AX foci increased as a function of linear energy transfer (LET) and RBE, reminiscent of enhanced DNA-damage complexity and accumulation of non-repairable DSB. These data confirm the high relevance of complex DSB formation as a central determinant of cell fate and reliable biological surrogates for cell survival/ RBE. The multi-scale simulation, physical and radiobiological characterization of novel clinical quality beams presented here constitutes a first step towards development of high precision biologically individualized radiotherapy.

Carbon ion therapy (C12) for high-grade malignant salivary gland tumors (MSGTs) of the head and neck: do non-ACCs profit from dose escalation?

Purpose

To evaluate the use of high-dose radiotherapy using carbon ions (C12) on non-adenoid cystic malignant salivary gland tumors (MSGT).

Patients and methods

Between 2009 and 2013, patients with biopsy-proven non-ACC MSGT histologies of the head and neck received a combined regimen of IMRT plus C12 boost. Treatment toxicity (CTC v3), response (RECIST 1.1), control and survival rates were retrospectively analyzed.

Results

40 patients with pathologically confirmed non-ACC MSGT (T4: 45 %; N+: 40 %; gross residual: 58 %; mucoepidermoid carcinoma (MEC): 45 %; adenocarcinoma: 20 %) were treated with a median of 74 GyE (80 Gy BED). Chemoradiation was given in 5 patients with MEC. Grade III acute toxicity was observed in up to 15 % (mucositis, dermatitis, dysphagia), no higher-grade late toxicity occurred to date. At a follow-up of 25.5 months, LC, and PFS at 2 and 3 years are 81.5 % (LC) and 66.8 % (PFS), OS at 2 and 3 years is 83.6 % and 72.8 %. Most frequent site of disease progression was distant metastasis. Histologic subtype correlated with LC and PFS. Resection status (gross vs microscopic disease) had no significant effect on LC, PFS, or OS.

Conclusion

The treatment is well tolerated, no higher grade late effects were observed. Considering the negative pre-selection, LC, PFS and OS are promising. While histology and site of origin significantly influenced control and survival rates, resection status did not, potentially due to the effect of dose escalation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0657-z) contains supplementary material, which is available to authorized users.

Intensity-modulated radiotherapy versus proton radiotherapy versus carbon ion radiotherapy for spinal bone metastases: a treatment planning study

Outcomes for selected patients with spinal metastases may be improved by dose escalation using stereotactic body radiotherapy (SBRT). As target geometry is complex, we compared SBRT plans using step‐and‐shoot intensity‐modulated radiotherapy (IMRT), carbon ion RT, and proton RT. We prepared plans treating cervical, thoracic, and lumbar metastases for three different techniques — IMRT, carbon ion, and proton plans — to deliver a median single 24 Gy fraction such that at least 90% of the planning target volume (PTV) received more than 18 Gy and were compared for PTV coverage, normal organ sparing, and estimated delivery time. PTV coverage did not show significant differences for the techniques, spinal cord dose sparing was lowered with the particle techniques. For the cervical lesion spinal cord maximum dose, dose of 1% (D1), and percent volume receiving 10 Gy (V10Gy) were 11.9 Gy, 9.1 Gy, and 0.5% in IMRT. This could be lowered to 4.3 Gy, 2.5 Gy, and 0% in carbon ion planning and to 8.1 Gy, 6.1 Gy, and 0% in proton planning. Regarding the thoracic lesion no difference was found for the spinal cord. For the lumbar lesion maximum dose, D1 and percent volume receiving 5 Gy (V5Gy) were 13.4 Gy, 8.9 Gy, and 8.9% for IMRT; 1.8 Gy, 0.7 Gy, and 0% for carbon ions; and 0 Gy,<0.01 Gy, and 0% for protons. Estimated mean treatment times were shorter in particle techniques (6–7 min vs. 12–14 min with IMRT). This planning study indicates that carbon ion and proton RT can deliver high‐quality PTV coverage for complex treatment volumes that surround the spinal cord.

PACS number: 87.55.dk

Carbon Ion irradiation in the treatment of grossly incomplete or unresectable malignant peripheral nerve sheaths tumors: acute toxicity and preliminary outcome

Background

To report our early experience with carbon ion irradiation in the treatment of gross residual or unresectable malignant peripheral nerve sheath tumors (MPNST).

Methods

We retrospectively analysed 11 patients (pts) with MPNST, who have been treated with carbon ion irradiation (C12) at our institution between 2010 and 2013. All pts had measurable gross disease at the initiation of radiation treatment. Median age was 47 years (29-79). Tumors were mainly located in the pelvic/sacral (5 pts) and sinunasal/orbital region (5 pts). 5 pts presented already in recurrent situation, 3 pts had been previously irradiated, and in 3 pts MPNST were neurofibromatosis type 1 (NF1) associated. Median cumulative dose was 60 GyE. Treatment was carried out either as a combination of IMRT plus C12 boost (4 pts) or C12 only (7 pts).

Results

Median follow-up was 17 months (3-31 months). We observed 3 local progressions, translating into estimated 1- and 2-year local control rates of 65%. One patient developed distant failure, resulting in estimated 1- and 2-year PFS rates of 56%. Two patients have died, therefore the estimated 1- and 2-year OS rates are 75%. Acute radiation related toxicities were generally mild, no grade 3 side effects were observed. Severe late toxicity (grade 3) was scored in 2 patients (trismus, wound healing delays).

Conclusion

Carbon ion irradiation yields very promising short term local control and overall survival rates with low morbidity in patients suffering from gross residual or unresectable malignant peripheral nerve sheath tumors and should be further investigated in a prospective trial.

Re-irradiation of adenoid cystic carcinoma: analysis and evaluation of outcome in 52 consecutive patients treated with raster-scanned carbon ion therapy

BACKGROUND

Treatment of local relapse in adenoid cystic carcinoma (ACC) following prior radiation remains a challenge: without the possibility of surgical salvage patients face the choice between palliative chemotherapy and re-irradiation. Chemotherapy yields response rates around 30% and application of tumouricidal doses is difficult due to proximity of critical structures. Carbon ion therapy (C12) is a promising method to minimize side-effects and maximize re-treatment dose in this indication. We describe our initial results for re-irradiation in heavily pre-treated ACC patients.

METHODS

Patients treated with carbon ion therapy between 04/2010 and 05/2013 (N=52pts, median age: 54 a) were retrospectively evaluated regarding toxicity (NCI CTC v.4), tumour response (RECIST) and control rates. 48pts (92.3%) received carbon ions only, 4pts received IMRT plus C12.

RESULTS

4pts were treated following R1-resection, 43pts for inoperable local relapse. Most common tumour sites were paranasal sinus (36.5%), parotid (19.2%), and base of skull (17.3%). Pts received a median dose of 51GyE C12/63Gy BED and cumulative dose of 128Gy BED [67-182Gy] after a median RT-interval of 61months. Median target volume was 93ml [9-618ml]. No higher-grade (>°II) acute reactions were observed, 7pts showed blood-brain-barrier changes (°I/II: 8pts; °III: 2pts), 1 pt corneal ulceration, xerophthalmia 7pts, °IV bleeding 1 pt, tissue necrosis 2pts, otherwise no significant late reactions. Objective response rate (CR/PR) was 56.6%. With a median follow-up of 14months [1-39months] local control and distant control at 1a are 70.3% and 72.6% respectively. Of the 18pts with local relapse, 13pts have recurred in-field, 1 pt at the field edge, 3pts out of field, and one in the dose gradient.

CONCLUSION

Despite high applied doses, C12 re-irradiation shows moderate side-effects, response rates even in these heavily pre-treated patients are encouraging and present a good alternative to palliative chemotherapy. Though most local recurrences occur within the high-dose area, further dose escalation should be viewed with caution.

Inactivating the infralimbic but not prelimbic medial prefrontal cortex facilitates the extinction of appetitive Pavlovian conditioning in Long-Evans rats

The infralimbic medial prefrontal cortex (IL) has been posited as a common node in distinct neural circuits that mediate the extinction of appetitive and aversive conditioning. However, appetitive extinction is typically assessed using instrumental conditioning procedures, whereas the extinction of aversive conditioning is customarily studied using Pavlovian assays. The role of the IL in the extinction of appetitive Pavlovian conditioning remains underexplored. We investigated the involvement of the IL and prelimbic medial prefrontal cortex (PrL) in appetitive extinction in Pavlovian and instrumental conditioning assays in male, Long-Evans rats. Following acquisition, a gamma-aminobutyric acid agonist solution (0.03 nmol muscimol; 0.3 nmol baclofen; 0.3 μl/side) was bilaterally microinfused into the IL or PrL to pharmacologically inactivate each region before the first extinction session. Compared to saline, PrL inactivation did not affect the acquisition of extinction or the recall of extinction memory 24-h later. IL inactivation caused a more rapid extinction of Pavlovian conditioning, but had no effect on the extinction of instrumental conditioning or extinction recall. IL inactivation during a Pavlovian conditioning session in which conditioned stimulus (CS) trials were paired with sucrose did not affect CS-elicited behaviour, but increased responding during intervals that did not contain the CS. The same manipulation did not impact lever pressing for sucrose. These findings suggest that the IL may normally maintain Pavlovian conditioned responding when an anticipated appetitive CS is unexpectedly withheld, and that this region has distinct roles in the expression of Pavlovian conditioning when an appetitive unconditioned stimulus is either presented or omitted.

Unilateral inactivation of the basolateral amygdala attenuates context-induced renewal of Pavlovian-conditioned alcohol-seeking

Environmental contexts associated with drug use promote craving in humans and drug-seeking in animals. We hypothesized that the basolateral amygdala (BLA) itself as well as serial connectivity between the BLA and nucleus accumbens core (NAC core) were required for context-induced renewal of Pavlovian-conditioned alcohol-seeking. Male Long-Evans rats were trained to discriminate between two conditioned stimuli (CS): a CS+ that was paired with ethanol (EtOH, 20%, v/v) delivery into a fluid port (0.2 mL/CS+, 3.2 mL per session) and a CS- that was not. Entries into the port during each CS were measured. Next, rats received extinction in a different context where both cues were presented without EtOH. At test, responding to the CS+ and CS- without EtOH was evaluated in the prior training context. Control subjects showed a selective increase in CS+ responding relative to extinction, indicative of renewal. This effect was blocked by pre-test, bilateral inactivation of the BLA using a solution of GABA receptor agonists (0.1 mm muscimol and 1.0 mm baclofen; M/B; 0.3 μL per side). Renewal was also attenuated following unilateral injections of M/B into the BLA, combined with either M/B, the dopamine D1 receptor antagonist SCH 23390 (0.6 μg per side) or saline infusion in the contralateral NAC core. Hence, unilateral BLA inactivation was sufficient to disrupt renewal, highlighting a critical role for functional activity in the BLA in enabling the reinstatement of alcohol-seeking driven by an alcohol context.

Recommended screening and preventive practices for long-term survivors after hematopoietic cell transplantation

Advances in hematopoietic cell transplantation (HCT) technology and supportive care techniques have led to improvements in long-term survival after HCT. Emerging indications for transplantation, introduction of newer graft sources (eg, umbilical cord blood) and transplantation of older patients using less intense conditioning regimens have also contributed to an increase in the number of HCT survivors. These survivors are at risk for developing late complications secondary to pre-, peri-, and posttransplant exposures and risk factors. Guidelines for screening and preventive practices for HCT survivors were published in 2006. An international group of transplantation experts was convened in 2011 to review contemporary literature and update the recommendations while considering the changing practice of transplantation and international applicability of these guidelines. This review provides the updated recommendations for screening and preventive practices for pediatric and adult survivors of autologous and allogeneic HCT.

Dosimetric precision of an ion beam tracking system

Background

Scanned ion beam therapy of intra-fractionally moving tumors requires motion mitigation. GSI proposed beam tracking and performed several experimental studies to analyse the dosimetric precision of the system for scanned carbon beams.

Methods

A beam tracking system has been developed and integrated in the scanned carbon ion beam therapy unit at GSI. The system adapts pencil beam positions and beam energy according to target motion.

Motion compensation performance of the beam tracking system was assessed by measurements with radiographic films, a range telescope, a 3D array of 24 ionization chambers, and cell samples for biological dosimetry. Measurements were performed for stationary detectors and moving detectors using the beam tracking system.

Results

All detector systems showed comparable data for a moving setup when using beam tracking and the corresponding stationary setup. Within the target volume the mean relative differences of ionization chamber measurements were 0.3% (1.5% standard deviation, 3.7% maximum). Film responses demonstrated preserved lateral dose gradients. Measurements with the range telescope showed agreement of Bragg peak depth under motion induced range variations. Cell survival experiments showed a mean relative difference of -5% (-3%) between measurements and calculations within the target volume for beam tracking (stationary) measurements.

Conclusions

The beam tracking system has been successfully integrated. Full functionality has been validated dosimetrically in experiments with several detector types including biological cell systems.

Speed and accuracy of a beam tracking system for treatment of moving targets with scanned ion beams

The technical performance of an integrated three-dimensional carbon ion pencil beam tracking system that was developed at GSI was investigated in phantom studies. Aim of the beam tracking system is to accurately treat tumours that are subject to respiratory motion with scanned ion beams. The current system provides real-time control of ion pencil beams to track a moving target laterally using the scanning magnets and longitudinally with a dedicated range shifter. The system response time was deduced to be approximately 1 ms for lateral beam tracking. The range shifter response time has been measured for various range shift amounts. A value of 16 +/- 2 ms was achieved for a water equivalent shift of 5 mm. An additional communication delay of 11 +/- 2 ms was taken into account in the beam tracking process via motion prediction. Accuracy of the lateral beam tracking was measured with a multi-wire position detector to < or =0.16 mm standard deviation. Longitudinal beam tracking accuracy was parameterized based on measured responses of the range shifter and required time durations to maintain a specific particle range. For example, 5 mm water equivalence (WE) longitudinal beam tracking results in accuracy of 1.08 and 0.48 mm WE in root mean square for time windows of 10 and 50 ms, respectively.

Special issues related to hematopoietic SCT in the Eastern Mediterranean region and the first regional activity report

Although several centers are now performing allogeneic hematopoietic SCT (HSCT) in the Eastern Mediterranean (EM) region, the availability is still limited. Special issues including compatible donor availability and potential for alternative donor programs are discussed. In comparison to Europe and North America, differences in patterns of diseases and pre-HSCT general status, particularly for patients with BM failure, are described. Other differences including high sero-positivity for CMV, hepatitis B and C infection, and specific observations about GVHD and its relation to genetically homogeneous communities are also discussed. We report that a total of 17 HSCT programs (performing five or more HSCTs annually) exist in 9 countries of the EM region. Only six programs are currently reporting to European Group for Blood and Marrow Transplantation or Center for International Blood and Marrow Transplantation Research. A total of 7617 HSCTs have been performed by these programs including 5701 allogeneic HSCTs. The area has low-HSCT team density (1.56 teams per 10 million inhabitants vs 14.43 in Europe) and very low-HSCT team distribution (0.27 teams per 10 000 sq km area vs <1-6 teams in Europe). Gross national income per capita had no clear association with low-HSCT activity. Much improvement in infrastructure and formation of an EM regional HSCT registry are needed.

Target motion tracking with a scanned particle beam

Treatment of moving targets with scanned particle beams results in local over- and under-dosage due to interplay of beam and target motion. To mitigate the impact of respiratory motion, a motion tracking system has been developed and integrated in the therapy control system at Gesellschaft für Schwerionenforschung. The system adapts pencil beam positions as well as the beam energy according to target motion to irradiate the planned position. Motion compensation performance of the tracking system was assessed by measurements with radiographic films and a 3D array of 24 ionization chambers. Measurements were performed for stationary detectors and moving detectors using the tracking system. Film measurements showed comparable homogeneity inside the target area. Relative differences of 3D dose distributions within the target volume were 1 +/- 2% with a maximum of 4%. Dose gradients and dose to surrounding areas were in good agreement. The motion tracking system successfully preserved dose distributions delivered to moving targets and maintained target conformity.

Second allogeneic bone marrow transplantation after myeloablative conditioning analysis of 43 cases from single institution

Between March 1984 and December 1999, a total of 43 second related allogeneic BMT procedures after myeloablative conditioning were carried out in our institution, 37 following allogeneic, and 6 following autologous BMT. Thirty one patients were males (72%). At 1st BMT (BMT1), median age was 11.5 years (range, 0.16-45 years). BMT1 was carried out for the diagnosis of AML in 13 patients (30%), SAA in nine (21%), ALL in six (14%), CML in six (14%), immunodeficiency in three (7%), NHL in two, beta-thal in two, HD in one, Red cell aplasia in one. HLA matching status for allogeneic BMT1 was full match in 33, one antigen mismatch in two and haplo identical in two patients. Median age at the 2nd BMT (BMT2) was 14 years (range, 0.41-46.7 years). Indications for BMT2 were recurrent hematologic neoplasm in 23 patients (53%), primary graft failure in 12 (28%) and late graft failure in 8 (19%). Median time from BMT1 to recurrence of hematologic neoplasm or late graft failure was 10 months (range, 2.5- 88 months). Median BMT1 to BMT2 interval was 13 months (range, 1-107 months). For BMT2, the same donor was used in 29 patients, while 14 patients had alternate related donor (12 full match, 1-one Ag mismatch, 1 haplo identical). A different conditioning regimen was used in the majority of the patients (39, 91%). Radiation containing conditioning regimen were used mostly for patients previously conditioned with chemotherapy only for BMT1 and chemotherapy conditioning +/- ATG for those who received radiation containing conditioning at BMT1. Bone marrow was the stem cell source for all patients at BMT2 and all except three autologous peripheral stem cell transplantation patient at BMT1. Significant organ toxicity leading to procedure related death in 13 patients (30%) was observed after BMT2. At a median follow up of 36 months after BMT2, 22 patients (51%) are alive (20 free of disease, 2 with recurrent disease) with overall median survival of 47.5 (SD +/- 9) months. Univariate analysis of relevant clinical factors identified the following variables as the only statistically significant favorable prognostic factors for overall survival: BMT1-BMT2 interval of > or = 6 months (P=0.0007) and age at BMT2 < or = 10 years (P=0.041). The nature of underlying disease (neoplastic or non-neoplastic) was not statistically significant (P=0.23). There was no statistically significant difference in survival outcome of BMT2 using same donor vs. alternate related donor (P=0.51). Due to the relatively limited sample size, multivariate analysis was not attempted. This single institution study suggests that second allogeneic BMT after myeloblative conditioning has an acceptable treatment related morbidity/mortality and favorable outcome if performed at age < or = 10 years and with an interval of > or = 6 months after the first BMT. Additionally same donor can successfully be used for the second transplant with similar survival outcome to alternate donor.

Cue dependency of nicotine self-administration and smoking

A paradox exists regarding the reinforcing properties of nicotine. The abuse liability associated with smoking equals or exceeds that of other addictive drugs, yet the euphoric, reinforcing and other psychological effects of nicotine, compared to these other drugs, are more subtle, are manifest under more restricted conditions, and do not readily predict the difficulty most smokers experience in achieving abstinence. One possible resolution to this apparent inconsistency is that environmental cues associated with drug delivery become conditioned reinforcers and take on powerful incentive properties that are critically important for sustaining smoking in humans and nicotine self-administration in animals. We tested this hypothesis by using a widely employed self-administration paradigm in which rats press a lever at high rates for 1 h/day to obtain intravenous infusions of nicotine that are paired with two types of visual stimuli: a chamber light that when turned on signals drug availability and a 1-s cue light that signals drug delivery. We show that these visual cues are at least as important as nicotine in sustaining a high rate of responding once self-administration has been established, in the degree to which withdrawing nicotine extinguishes the behavior, and in the reinstatement of lever pressing after extinction. Additional studies demonstrated that the importance of these cues was manifest under both fixed ratio and progressive ratio (PR) schedules of reinforcement. The possibility that nicotine-paired cues are as important as nicotine in smoking behavior should refocus our attention on the psychology and neurobiology of conditioned reinforcers in order to stimulate the development of more effective treatment programs for smoking cessation.

The spectrum of Fusarium infection in immunocompromised patients with haematological malignancies and in non-immunocompromised patients: a single institution experience over 10 years

Fusarium is a newly emerging fungal pathogen associated with significant morbidity and mortality in the immunocompromised host. We have reviewed our hospital's experience with Fusarium between 1985 and 1995. Fusarium species were isolated from 22 specimens, representing 11 patients. Cases were not clustered by time period. The median age of the patients was 36.5 years (range 17-69 years). The sources of the organism were 12 skin lesions from eight patients, seven blood cultures from two patients and one specimen each from a Hickman catheter tip, nail clippings and a bronchoalveolar lavage. Seven of the patients had chemotherapy-induced neutropenia when the Fusarium was isolated. Five of them developed invasive fusarosis during acute leukaemia induction treatment. They remained neutropenic, and none survived. The other two patients recovered from neutropenia and were treated successfully for this infection. The remaining four patients were not neutropenic or immunocompromised. Three grew Fusarium from skin or nail clippings and one from bronchial alveolar lavage (BAL). There was no evidence of invasive disease in any of the four. None of them received antifungal therapy, and they were all alive at last follow-up. We conclude that Fusarium is a newly emerging infection in neutropenic patients. A high index of suspicion, especially for skin lesions, will help in early diagnosis before systemic and visceral dissemination. Excision of the initial focus of infection and antifungal therapy, aided by speedy neutrophil recovery, are likely to protect patients threatened with these fatal infections. Fusarium isolated from non-neutropenic, non-immunosuppressed patients is not significant and does not merit systemic antifungal treatment.

Mycobacterium tuberculosis infection in allogeneic bone marrow transplantation patients

Bone marrow transplant (BMT) recipients are prone to bacterial, viral and fungal infections. Mycobacterium tuberculosis infection can occur in these patients, but the incidence is lower than that of other infections. This report describes four patients with Mycobacterium tuberculosis infection identified from 641 adult patients who received a BMT over a 12-year period (prevalence 0.6%). The pre-transplant diagnosis was AML in two patients and CML in the other two. Pre-transplant conditioning consisted of BU/CY in three patients and CY/TBI in one. Graft-versus-host disease (GVHD) prophylaxis was MTX/CsA in three patients and T cell depletion of the graft in one patient. Sites of infection were lung (two), spine (one) and central nervous system (one). Onset of infection ranged from 120 days to 20 months post BMT. Two patients had co-existing CMV infection. One patient had graft failure. The two patients who received anti-tuberculous (TB) therapy recovered from the infection. Although the incidence of tuberculosis in BMT patients is not as high as in patients with solid organ transplants, late diagnosis due to the slow growth of the bacterium can lead to delay in instituting anti-TB therapy. A high index of suspicion should be maintained, particularly in endemic areas.