A combined approach for the calculation of activation yields and the characterization of materials for a medical cyclotron

Cyclotrons for the production of radiopharmaceuticals have become important tools in modern nuclear medicine. At the end of their lifecycles, such installations have to be dismantled and any activated materials must be treated according to the local radiation protection legislation. Using a simulation model, we have developed a non-destructive approach for the radiological characterization of components inside and around an IBA Cyclone 18/9 cyclotron. The methodology is based on software tools developed at CERN (FLUKA Monte Carlo code, ActiWiz and RAW). The simulation results were compared to measurements made using reference samples placed around the cyclotron inside the bunker. Results show a reasonable agreement between simulation and measurements of about a factor of two for a set of 27 reference samples and 11 radionuclides of interest. The origin of this factor has been thoroughly evaluated and opened the door to further investigations leading to possible avenues for improvement.

Dosimetric and biologic intercomparison between electron and proton FLASH beams

BACKGROUND AND PURPOSE

The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at an average dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH effect produced by eFLASHvs. pFLASH has yet been performed and constitutes the aim of the present study.

MATERIALS AND METHODS

The electron eRT6/Oriatron/CHUV/5.5 MeV and proton Gantry1/PSI/170 MeV were used to deliver conventional (0.1 Gy/s eCONV and pCONV) and FLASH (≥110 Gy/s eFLASH and pFLASH) dose rates. Protons were delivered in transmission. Dosimetric and biologic intercomparisons were performed using previously validated dosimetric approaches and experimental murine models.

RESULTS

The difference between the average absorbed dose measured at Gantry 1 with PSI reference dosimeters and with CHUV/IRA dosimeters was -1.9 % (0.1 Gy/s) and + 2.5 % (110 Gy/s). The neurocognitive capacity of eFLASH and pFLASH irradiated mice was indistinguishable from the control, while both eCONV and pCONV irradiated cohorts showed cognitive decrements. Complete tumor response was obtained after an ablative dose of 20 Gy delivered with the two beams at CONV and FLASH dose rates. Tumor rejection upon rechallenge indicates that anti-tumor immunity was activated independently of the beam-type and the dose-rate.

CONCLUSION

Despite major differences in the temporal microstructure of proton and electron beams, this study shows that dosimetric standards can be established. Normal brain protection and tumor control were produced by the two beams. More specifically, normal brain protection was achieved when a single dose of 10 Gy was delivered in 90 ms or less, suggesting that the most important physical parameter driving the FLASH sparing effect might be the mean dose rate. In addition, a systemic anti-tumor immunological memory response was observed in mice exposed to high ablative dose of electron and proton delivered at CONV and FLASH dose rate.

Examining Alcohol-Related Blackouts and Drinking Motives Over Time Among College Women

OBJECTIVE

Excessive alcohol consumption and its consequences among college women continues despite prevention efforts. One common consequence, alcohol-related blackouts (ARBs), are periods of alcohol-activated anterograde amnesia. The purpose of the current project is to extend the ARB and drinking motive literature by examining their relationship over time.

METHOD

A sample of 424 women (88.9% White) completed online surveys assessing their ARBs and drinking motives weekly for 10 weeks. A series of hierarchical generalized linear models were estimated to examine the between-person and within-person effects of each drinking motive on repeated measures of experiencing a blackout across the time points.

RESULTS

Women who report higher levels of drinking motives compared with others were more likely to report having blackout experiences. College women who reported higher levels of conformity motives did not have increased odds of experiencing a blackout. In weeks when they reported elevated levels of drinking motives, they were also more likely to experience an ARB.

CONCLUSIONS

In general, college women who reported higher levels of social, coping, or enhancement motives experienced more blackouts than students who reported lower levels of these motives. Women who were underage were more likely to experience a blackout compared with women who were 21 or older. In a given week, 52.6% to 70.7% of the students consumed alcohol, and among women who drank in a given week, the prevalence of blackouts ranged from 8.5% to 14.6%. The results suggest that changes in motivational levels might provide a possible intervention point for ARBs risk.

Postacute Sequelae of SARS-CoV-2: Musculoskeletal Conditions and Pain

Musculoskeletal and pain sequelae of COVID-19 are common in both the acute infection and patients experiencing longer term symptoms associated with recovery, known as postacute sequelae of COVID-19 (PASC). Patients with PASC may experience multiple manifestations of pain and other concurrent symptoms that complicate their experience of pain. In this review, the authors explore what is currently known about PASC-related pain and its pathophysiology as well as strategies for diagnosis and management.

Dosimetric and biologic intercomparison between electron and proton FLASH beams

Background and purpose

The FLASH effect has been validated in different preclinical experiments with electrons (eFLASH) and protons (pFLASH) operating at a mean dose rate above 40 Gy/s. However, no systematic intercomparison of the FLASH effect produced by e vs. pFLASH has yet been performed and constitutes the aim of the present study.

Materials and methods

The electron eRT6/Oriatron/CHUV/5.5 MeV and proton Gantry1/PSI/170 MeV were used to deliver conventional (0.1 Gy/s eCONV and pCONV) and FLASH (≥100 Gy/s eFLASH and pFLASH) irradiation. Protons were delivered in transmission. Dosimetric and biologic intercomparisons were performed with previously validated models.

Results

Doses measured at Gantry1 were in agreement (± 2.5%) with reference dosimeters calibrated at CHUV/IRA. The neurocognitive capacity of e and pFLASH irradiated mice was indistinguishable from the control while both e and pCONV irradiated cohorts showed cognitive decrements. Complete tumor response was obtained with the two beams and was similar between e and pFLASH vs. e and pCONV. Tumor rejection was similar indicating that T-cell memory response is beam-type and dose-rate independent.

Conclusion

Despite major differences in the temporal microstructure, this study shows that dosimetric standards can be established. The sparing of brain function and tumor control produced by the two beams were similar, suggesting that the most important physical parameter driving the FLASH effect is the overall time of exposure which should be in the range of hundreds of milliseconds for WBI in mice. In addition, we observed that immunological memory response is similar between electron and proton beams and is independent off the dose rate.

Detailed study of the distribution of activation inside the magnet coils of a compact PET cyclotron

We determined the distribution of activation products inside the magnet coils of a medical cyclotron that has been operational for fifteen years. Besides FLUKA, we based our approach on new software tools (RAW and ActiWiz) developed for high-energy accelerators at CERN. A combined analysis of measurements on the coils with Monte-Carlo simulations resulted in a detailed three-dimensional radiological characterisation of the coils. Our results provide the required information for the radiation protection expert to identify the appropriate waste elimination scheme.

The epidemiology of benzodiazepine misuse: A systematic review

BACKGROUND

Benzodiazepine misuse is a growing public health problem, with increases in benzodiazepine-related overdose deaths and emergency room visits in recent years. However, relatively little attention has been paid to this emergent problem. We systematically reviewed epidemiological studies on benzodiazepine misuse to identify key findings, limitations, and future directions for research.

METHODS

PubMed and PsychINFO databases were searched through February 2019 for peer-reviewed publications on benzodiazepine misuse (e.g., use without a prescription; at a higher frequency or dose than prescribed). Eligibility criteria included human studies that focused on the prevalence, trends, correlates, motives, patterns, sources, and consequences of benzodiazepine misuse.

RESULTS

The search identified 1970 publications, and 351 articles were eligible for data extraction and inclusion. In 2017, benzodiazepines and other tranquilizers were the third most commonly misused illicit or prescription drug in the U.S. (approximately 2.2% of the population). Worldwide rates of misuse appear to be similar to those reported in the U.S. Factors associated with misuse include other substance use, receipt of a benzodiazepine prescription, and psychiatric symptoms and disorders. Benzodiazepine misuse encompasses heterogeneous presentations of motives, patterns, and sources. Moreover, misuse is associated with myriad poor outcomes, including mortality, HIV/HCV risk behaviors, poor self-reported quality of life, criminality, and continued substance use during treatment.

CONCLUSIONS

Benzodiazepine misuse is a worldwide public health concern that is associated with a number of concerning consequences. Findings from the present review have implications for identifying subgroups who could benefit from prevention and treatment efforts, critical points for intervention, and treatment targets.

Nonmedical benzodiazepine use in adults with alcohol use disorder: The role of anxiety sensitivity and polysubstance use

BACKGROUND AND OBJECTIVES

The nonmedical use of benzodiazepines-defined as use without a prescription or at a dose or frequency higher than prescribed-is increasing among adults in substance use disorder treatment and is associated with risk for overdose. The aim of the current study was to characterize the prevalence of nonmedical benzodiazepine use among adults seeking treatment for alcohol use disorder and to examine whether nonmedical benzodiazepine use was associated with: (1) polysubstance use and (2) greater anxiety sensitivity.

METHODS

A sample of 461 treatment-seeking adults with alcohol use disorder who were recruited for a cross-sectional study were included in this analysis.

RESULTS

A total of 89 participants (19%) reported nonmedical benzodiazepine use in the previous 30 days. Results of a logistic regression indicated that polysubstance use (number of substances used in the past month) was associated with nonmedical benzodiazepine use. The association between anxiety sensitivity and nonmedical benzodiazepine misuse was moderated by gender; anxiety sensitivity was associated with benzodiazepine use among women, but not men.

DISCUSSION AND CONCLUSIONS

These results replicate findings from research on opioid use disorder suggesting that anxiety sensitivity is associated with nonmedical benzodiazepine use in women and not men.

SCIENTIFIC SIGNIFICANCE

Targeted intervention to those with polysubstance use-including education on overdose risk when benzodiazepines are combined with other substances-is indicated in men and women with alcohol use disorder. Anxiety sensitivity may be a potential therapeutic target to reduce nonmedical benzodiazepine use among women with alcohol use disorder. (Am J Addict 2018;27:485-490).

The Fluid Perception of Racial Identity

Scholars view racial identity as a fluid social construction that can shift with time and context. But outside of academia, do people intuitively see racial identity as fluid or fixed? Four studies reveal that people see racial identity as varying flexibly with the social context—in particular, assimilating to the race of one’s friends. Participants perceived the same Black–White Biracial men as identifying as more Black (Study 1) and wanting to be perceived as more stereotypically Black (i.e., athletic; Study 3c) when with Black friends than when alone. Conversely, Biracial men were perceived as identifying as more White (Study 2) and wanting to be perceived as more stereotypically White (i.e., competent and well-spoken; Studies 3a, 3b) when with White friends. Fluid inferences of racial identity also extended to Monoracial people (Studies 4a, 4b). We conclude that people perceive others’ racial identity as shifting with the social context—eliciting distinct biases.

Measurement of the charged-pion polarizability

The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015  (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4)  fm(3) under the assumption α(π)=-β(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

First measurement of chiral dynamics in π- γ → π- π- π+

The COMPASS Collaboration at CERN has investigated the π- γ → π- π- π+ reaction at center-of-momentum energy below five pion masses, sqrt[s]<5m(π), embedded in the Primakoff reaction of 190 GeV pions impinging on a lead target. Exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, t'<0.001  GeV2/c2. Using partial-wave analysis techniques, the scattering intensity of Coulomb production described in terms of chiral dynamics and its dependence on the 3π-invariant mass m(3π)=sqrt[s] were extracted. The absolute cross section was determined in seven bins of sqrt[s] with an overall precision of 20%. At leading order, the result is found to be in good agreement with the prediction of chiral perturbation theory over the whole energy range investigated.

Analysis of rainbow trout Oncorhynchus mykiss epidermal mucus and evaluation of semiochemical activity for polar filament discharge in Myxobolus cerebralis actinospores

As myxozoan actinospores are stimulated by fish epidermal mucus to attach to their hosts via extrusion of filaments from specialized organelles, the polar capsules, mucus components were tested for discharge triggering activity on Myxobolus cerebralis actinospores. Using various methodological approaches, a selective exclusion of candidate substances based on experimental outcome is provided and the physiochemical traits of the putative agents are explored to create a basis for the isolation of the host recognition chemostimuli. Activity was detected in compounds that can be characterized as small molecular, amphiphilic to slightly hydrophobic organic substances. They were separable by chromatographic methods using reversed phase C18 supports. An active fraction was isolated by solid phase extraction comprising at least nine UV-detectable constituents as shown by thin-layer chromatography. By means of biochemical fractionation and analysis of host fish mucus, non-volatile inorganic electrolytes, all volatiles, free L-amino acids, glycoproteins, bound and free hexoses, sialic acids, glycans, proteins, urea, amines and inositols were shown not to trigger polar filament discharge. The results contribute to the identification of the attachment host cues and enable a more focused laboratory activation of myxozoan actinospores.

Observation of a J(PC)=1-+ exotic resonance in diffractive dissociation of 190 GeV/c π- into π- π- π+

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.

Characterization of a soluble oxidoreductase from the thermophilic bacterium Carboxydothermus ferrireducens

An NAD(P)H-dependent oxidoreductase has been purified approximately 40-fold from the soluble protein fraction of the dissimilatory iron-reducing, anaerobic, thermophilic bacterium Carboxydothermus ferrireducens. The enzyme, a flavoprotein, has broad-substrate specificity-reducing Fe(3+), Cr(6+), and AQDS with rates of 0.31, 0.33, and 3.3 U mg(-1) protein and calculated NADH oxidation turnover numbers of 0.25, 0.25, and 2.5 s(-1), respectively. Numerous quinones are reduced via a two-electron transfer from NAD(P)H to quinone, thus participating in managing oxidative stress by avoiding the formation of semiquinone radicals.

Downregulation of RIZ1 protein expression in left-sided versus right-sided primary colorectal carcinomas and their distant metastases and the association with NF-B activation

e15112

Background: Activation of NF- B leads to enhanced proliferation and the expression of anti-apoptotic proteins, which are cancer phenotypes. RIZ1 inactivation through various molecular events was linked to increased proliferation, migration induction and apoptosis inhibition in human cancer. RIZ1 frameshift mutations were recently reported to be confined to MSI-H colorectal tumors and proximal tumor origin, while its hypermethylation was not limited to MSI-H tumors. However, RIZ1 protein expression has not been evaluated in colorectal carcinoma. Methods: TMAs included 28 left-sided and 12 right-sided primary colorectal adenocarcinomas, their matched normal mucosa and their respective distant metastases. Left-sided tumors were compared to right-sided tumors for expression of RIZ1 protein and NF- B activation. RIZ1 immunostaining was scored semiquantitatively (0–3+). NF- B activation was determined by IHC detecting nuclear translocation of its p65 subunit in more than 30% tumor nuclei. Discrepant results were defined as score difference of 2. Results: RIZ1 was less expressed in tumors than in benign mucosa (p<0.0001, r=- 0.377, Chi-Square). The difference between primary vs. metastatic carcinoma was not significant. Low RIZ1 was associated with NF- B activation (p<0.0001, Linear-by-Linear). Left-sided primary tumors showed less RIZ1 protein expression than right-sided (p=0.03, Chi-Square). NF- B activation was more frequent in left-sided primary tumors and their respective metastases (35% in right vs. 67% in left; p=0.002, Chi-Square Test). RIZ1 expression and NF- B activation were almost identical in primary and their respective metastatic tumors with only 3 discrepant results for NF- B status and 2 discrepant results in RIZ1 expression. Conclusions: While RIZ1 downregulation in colorectal adenocarcinoma due to RIZ1 mutations appears to be associated with MSI-H and proximal origin, its protein expression appears to be downregulated more often in distal tumors. NF- B activation is strongly associated with lower RIZ1 protein expression in colorectal adenocarcinoma.

No significant financial relationships to disclose.

Novel chemolithotrophic, thermophilic, anaerobic bacteria Thermolithobacter ferrireducens gen. nov., sp. nov. and Thermolithobacter carboxydivorans sp. nov

Three thermophilic strains of chemolithoautotrophic Fe(III)-reducers were isolated from mixed sediment and water samples (JW/KA-1 and JW/KA-2(T): Calcite Spring, Yellowstone N.P., WY, USA; JW/JH-Fiji-2: Savusavu, Vanu Levu, Fiji). All were Gram stain positive rods (approximately 0.5 x 1.8 microm). Cells occurred singly or in V-shaped pairs, and they formed long chains in complex media. All utilized H(2) to reduce amorphous iron (III) oxide/hydroxide to magnetite at temperatures from 50 to 75 degrees C (opt. approximately 73 degrees C). Growth occurred within the pH(60C) range of 6.5-8.5 (opt. pH(60C) 7.1-7.3). Magnetite production by resting cells occurred at pH(60C) 5.5-10.3 (opt. 7.3). The iron (III) reduction rate was 1.3 mumol Fe(II) produced x h(-1) x ml(-1) in a culture with 3 x 10(7) cells, one of the highest rates reported. In the presence or absence of H(2), JW/KA-2(T) did not utilize CO. The G + C content of the genomic DNA of the type strain is 52.7 +/- 0.3 mol%. Strains JW/KA-1 and JW/KA-2(T) each contain two different 16S rRNA gene sequences. The 16S rRNA gene sequences from JW/KA-1, JW/KA-2(T), or JW/JH-Fiji-2 possessed >99% similarity to each other but also 99% similarity to the 16S rRNA gene sequence from the anaerobic, thermophilic, hydrogenogenic CO-oxidizing bacterium 'Carboxydothermus restrictus' R1. DNA-DNA hybridization between strain JW/KA-2(T) and strain R1(T) yielded 35% similarity. Physiological characteristics and the 16S rRNA gene sequence analysis indicated that the strains represent two novel species and are placed into the novel genus Thermolithobacter within the phylum 'Firmicutes'. In addition, the levels of 16S rRNA gene sequence similarity between the lineage containing the Thermolithobacter and well-established members of the three existing classes of the 'Firmicutes' is less than 85%. Therefore, Thermolithobacter is proposed to constitute the first genus within a novel class of the 'Firmicutes', Thermolithobacteria. The Fe(III)-reducing Thermolithobacter ferrireducens gen. nov., sp. nov. is designated as the type species with strain JW/KA-2(T) (ATCC 700985(T), DSM 13639(T)) as its type strain. Strain R1(T) is the type strain for the hydrogenogenic, CO-oxidizing Thermolithobacter carboxydivorans sp. nov. (DSM 7242(T), VKM 2359(T)).

Dissecting Ascaris glycosphingolipids for immunomodulatory moieties - the use of synthetic structural glycosphingolipid analogues

We have previously shown glycosphingolipids of Ascaris suum to have phosphorylcholine (PC) and non-PC immunomodulatory moieties. In the present study we further investigated the nature of the immunomodulatory moieties by employing three synthetic glycosphingolipids each possessing features of the original molecule to examine effects on macrophage and dendritic cell (DC) cytokine production and surface co-stimulatory molecule expression. Compound 2, which lacked PC but contained ceramide, had no effect on either macrophages or DCs. Surprisingly however, Compound 1, which contained PC and hence arguably most resembled the native material, had, with the exception of a small increase in surface antigen expression, no immunomodulatory properties. Conversely, Compound 3, which contained PC but was otherwise least like the native molecule, demonstrated a number of effects on both macrophages and DCs, including induction of Th-1/pro-inflammatory cytokines, inhibition of such cytokines induced by IFN-gamma/LPS and increased expression of co-stimulatory molecules. Taken together these results indicate: (i) that although PC is an immunomodulatory component of the native molecule other structural feature are necessary to allow it to act; (ii) that carbohydrate rather than ceramide is likely to represent a non-PC immunomodulatory moiety; and (iii) that synthetic PC-containing molecules have the potential to act as immunomodulatory drugs.

Lack of immunological cross-reactivity between parasite-derived and recombinant forms of ES-62, a secreted protein of Acanthocheilonema viteae

The longevity of filarial nematodes is dependent on secreted immunomodulatory products. Previous investigation of one such product, ES-62, has suggested a critical role for post-translationally attached phosphorylcholine (PC) moieties. In order to further investigate this, ES-62 lacking PC was produced, using the Pichia pastoris recombinant gene expression system. Unlike parasite-derived ES-62, which is tetrameric the recombinant material was found to consist of a mixture of apparently stable tetramers, dimers and monomers. Nevertheless, the recombinant protein was considered to be an adequate PC-free ES-62 as it was recognized by existing antisera against the parasite-derived protein. However, subsequent to this, recognition of parasite-derived ES-62 by antibodies produced against the recombinant protein was found to be absent. In an attempt to explain this, recombinant ES-62 was subjected to structural analysis and was found to (i) contain 3 changes in amino acid composition; (ii) demonstrate significant alterations in glycosylation; (iii) show major differences in protein secondary structure. The effects of these alterations in relation to the observed change in immunogenicity were investigated and are discussed. The data presented clearly show that recognition by existing antibodies is insufficient proof that recombinant proteins can be used to mimic parasite-derived material in studies on nematode immunology and vaccination.

In situ assessment of biodegradation potential using biotraps amended with 13C-labeled benzene or toluene

Stable isotope fractionation analysis of an aquifer heavily contaminated with benzene (up to 850 mg L(-1)) and toluene (up to 50 mg L(-1)) at a former hydrogenation plant in Zeitz (Saxonia, Germany) has suggested that significant biodegradation of toluene was occurring. However, clear evidence of benzene biodegradation has been lacking at this site. Determining the fate of benzene is often a determining factor in regulatory approval of a risk-based management strategy. The objective of the work described here was the demonstration of a new tool that can be used to provide proof of biodegradation of benzene or other organics by indigenous microorganisms under actual aquifer conditions. Unique in situ biotraps containing Bio-Sep beads, amended with 13C-labeled or 12C nonlabeled benzene and toluene, were deployed at the Zeitz site for 32 days in an existing groundwater monitoring well and used to collect and enrich microbial biofilms. Lipid biomarkers or remaining substrate was extracted from the beads and analyzed by mass spectrometry and molecular methods. Isotopic analysis of the remaining amounts of 13C-labeled contaminants (about 15-18% of the initial loading) showed no alteration of the 12C/13C ratio during incubation. Therefore, no measurable exchange of labeled compounds in the beads by the nonlabeled compounds in the aquifer materials occurred. Isotopic ratio analysis of microbial lipid fatty acids (as methyl ester derivatives) from labeled benzene- and toluene-amended biotraps showed 13C enrichment in several fatty acids of up to delta (13C) 13400%o, clearly verifying benzene and toluene biodegradation and the transformation of the labeled carbon into biomass by indigenous organisms under aquifer conditions. Fatty acid profiles of total lipid fatty acids and the phospholipid fatty acid fraction and their isotopic composition showed significant differences between benzene- and toluene-amended biotraps, suggesting that different microbial communities were involved in the biodegradation of the two compounds.

First measurement of the transverse spin asymmetries of the deuteron in semi-inclusive deep inelastic scattering

First measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarized 6LiD target are presented. The data were taken in 2002 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins asymmetry turns out to be compatible with zero, as does the measured Sivers asymmetry within the present statistical errors.

Mapping fucosylated epitopes on glycoproteins and glycolipids ofSchistosoma mansonicercariae, adult worms and eggs

The developmental expression of the antigenic fucosylated glycan motifs Fucα1-3GalNAcβ1-4GlcNAc (F-LDN), Fucα1-3GalNAcβ1-4(Fucα1-3)GlcNAc (F-LDN-F), GalNAcβ1-4(Fucα1-3)GlcNAc (LDN-F), Galβ1-4(Fucα1-3)GlcNAc (Lewis X), and GalNAcβ1-4(Fucα1-2Fucα1-3)GlcNAc (LDN-DF) inSchistosoma mansonicercariae, adult worms and eggs, was surveyed using previously defined anti-carbohydrate monoclonal antibodies (mAbs). Lewis X was found both on glycolipids and glycoproteins, yet with completely different expression patterns during the life-cycle: on glycolipids, Lewis X was mainly found in the cercarial stage, while protein-conjugated Lewis X was mainly present in the egg stage. Also protein-conjugated LDN-F and LDN-DF were most highly expressed in the egg-stage. On glycolipids LDN-DF was found in all three examined stages, whereas LDN-F containing glycolipids were restricted to adult worms and eggs. The motifs F-LDN and F-LDN-F were found both on glycoproteins and glycolipids of the cercarial and egg stage, while in the adult stage, they appeared to occur predominantly on glycolipids. Immunofluorescence assays (IFA) showed that these F-LDN and F-LDN-F containing glycolipids were localized in a yet undefined duct or excretory system of adult worms. Murine infection serum showed major reactivity with this adult worm duct-system, which could be fully inhibited by pre-incubation with keyhole limpet haemocyanin (KLH). Clearly, the use of defined mAbs provides a quick and convenient way to map expression profiles of carbohydrate epitopes.

Utilization of microbial biofilms as monitors of bioremediation

A down-well aquifer microbial sampling system was developed using glass wool or Bio-Sep beads as a solid-phase support matrix. Here we describe the use of these devices to monitor the groundwater microbial community dynamics during field bioremediation experiments at the U.S. Department of Energy Natural and Accelerated Bioremediation Research Program's Field Research Center at the Oak Ridge National Laboratory. During the 6-week deployment, microbial biofilms colonized glass wool and bead internal surfaces. Changes in viable biomass, community composition, metabolic status, and respiratory state were reflected in sampler composition, type of donor, and groundwater pH. Biofilms that formed on Bio-Sep beads had 2-13 times greater viable biomass; however, the bead communities were less metabolically active [higher cyclopropane/monoenoic phospholipid fatty acid (PLFA) ratios] and had a lower aerobic respiratory state (lower total respiratory quinone/ PLFA ratio and ubiquinone/menaquinone ratio) than the biofilms formed on glass wool. Anaerobic growth in these systems was characterized by plasmalogen phospholipids and was greater in the wells that received electron donor additions. Partial 16S rDNA sequences indicated that Geobacter and nitrate-reducing organisms were induced by the acetate, ethanol, or glucose additions. DNA and lipid biomarkers were extracted and recovered without the complications that commonly plague sediment samples due to the presence of clay or dissolved organic matter. Although microbial community composition in the groundwater or adjacent sediments may differ from those formed on down-well biofilm samplers, the metabolic activity responses of the biofilms to modifications in groundwater geochemistry record the responses of the microbial community to biostimulation while providing integrative sampling and ease of recovery for biomarker analysis.

An improved HPLC analysis of the metabolite furoic acid in the urine of workers occupationally exposed to furfural

An improved high-performance liquid chromatographic (HPLC) method for the analysis of the metabolite furoic acid in the urine of workers occupationally exposed to furfural is described. The procedure involved an alkaline hydrolysis step followed by solvent extraction using ethyl acetate. HPLC analysis used an acidic acetonitrile/water mobile phase with a C18 column and ultraviolet detection. The overall relative recovery of furoic acid in urine was found to be 98.8% with a relative standard deviation of 9.7%. The limit of quantitation was determined to be 0.01 mmol/L.

Bovine lymphocytes express functional receptors for Escherichia coli Shiga toxin 1

Interactions of Shiga toxins (Stxs) and immune cells contribute to the pathogenesis of diseases due to Stx-producing Escherichia coli (STEC) infections in humans and facilitate the persistence of infection in asymptomatically infected cattle. Our recent findings that bovine B and T lymphocytes express Gb(3)/CD77, the human Stx-receptor, prompted us to determine whether the bovine homologue also mediates binding and internalization of Stx1. In fact, Stx1 holotoxin and recombinant B subunit (rStxB1) bound to stimulated bovine peripheral blood mononuclear cells, especially to those subpopulations (B cells, BoCD8(+) T cells) that are highly sensitive to Stx1. Competition and HPTLC-binding studies confirmed that Stx1 binds to bovine Gb(3), but different receptor isoforms with varying affinities for rStxB1 were expressed during the course of lymphocyte activation. At least one of these isoforms mediated toxin uptake. An anti-StxB1 mouse monoclonal antibody, used as a model for bovine serum antibodies specific for Stx1, modulated rather than generally prevented rStxB1 binding to and internalization by the receptors. The presence of functional Stx1-receptors on bovine lymphocytes explains the immunomodulatory effect of Stx1 observed in cattle at a molecular level. Furthermore, expression of such receptors by bovine but not human T cells enlightens the background for the differential outcome of STEC infections in cattle and man, i.e., persistent infection and development of disease, respectively.

Measurement of spin-transfer observables in p p-->Lambda Lambda at 1.637 GeV/c

Spin-transfer observables for p p-->Lambda Lambda have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables Dnn and Knn (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of Dnn and Knn presented here are found to be in disagreement with predictions from these models.

Core structures of polysialylated glycans present in neural cell adhesion molecule from newborn mouse brain

Polysialylation of the neural cell adhesion molecule (N-CAM) is known to destabilize cell-cell adhesion and to promote plasticity in cell-cell interactions. To gain more insights into the molecular mechanisms regulating the selective expression of polysialic acid on distinct glycan chains, the underlying core structures of polysialylated N-CAM glycans from newborn mouse brain were examined. Starting from low picomolar amounts of oligosaccharides, a multistep approach was used that was based on various mass spectrometric techniques with minimized sample consumption. Evidence could be provided that polysialylated murine N-CAM glycans comprise diantennary, triantennary and tetraantennary core structures carrying, in part, type-1 N-acetyllactosamine antennae, sulfate groups linked to terminal galactose or subterminal N-acetylglucosamine residues and, as a characteristic feature, a sulfated glucuronic acid unit which was bound exclusively to C3 of terminal galactose in Manalpha3-linked type-2 antennae. Hence, our results reveal that part of the murine N-CAM carbohydrates are modified within a single oligosaccharide by polysialic acid plus a HSO3-GlcA-moiety, which is likely to represent a HNK1-epitope. As HNK1-carbohydrates are also known to modulate cell-cell interactions, the simultaneous presence of both carbohydrate epitopes may reflect a new mechanism involved in the fine-tuning of N-CAM functions.

Globotriaosylceramide (Gb(3)/CD77) is synthesized and surface expressed by bovine lymphocytes upon activation in vitro

Neutral glycosphingolipids (GSLs) are considered activation markers on human lymphocytes, which are fundamental for studying the immune system. For cattle, only a limited number of activation markers has yet been identified. We recently showed that Shiga toxin 1, known to use globotriaosylceramide (Gb(3) syn. CD77) as a cellular receptor, depresses proliferation of activated bovine lymphocytes [Infect. Immunol. 67 (1999b) 2209]. In order to confirm the expression of Gb(3)/CD77 on bovine lymphocytes, we flowcytometrically examined a bovine B-lymphoma cell line (BL-3) and bovine peripheral blood mononuclear cells (PBMC) before and after mitogenic stimulation and biochemically characterized neutral GSLs extracted from PBMC. CD77 was detected on the surface of BL-3 cells and cultured PBMC essentially after mitogenic stimulation. Although expressed by all PBMC subpopulations identified, the portion of CD7+ cells was highest for BoCD8+ cells, followed by B-cells and BoCD4+ cells at day 4 of cultivation. Ceramide trihexoside of stimulated PBMC was structurally determined as Gal(alpha1-4)Gal(1-4)Glc(1-1)ceramide (Gb(3)). Biochemically, Gb(3) was also detected within unstimulated PBMC which contained ceramide monohexoside (CMH) and Gb(3) in a ratio of about 4:1. However, stimulation induced an increase of CMH and Gb(3) by a factor of 2.5 and 10, respectively, implicating that bovine lymphocytes regulate surface expression of Gb(3)/CD77 predominantly by quantitative changes in the Gb(3) metabolism. This report presents Gb(3)/CD77 as the first GSL identified on bovine immune cells and highly recommends this activation dependent antigen as a useful tool to investigate lymphocyte activation within the bovine immune system.

Two glycoforms are present in the GPI-membrane anchor of the surface antigen 1 (P30) of Toxoplasma gondii

SAG1 (P30) is the major surface protein of the Toxoplasma gondii tachyzoite, the life cycle stage associated with the acute phase of infection. The protein is inserted into the parasite's plasma membrane by a glycosyl-phosphatidylinositol anchor, a modification that is present on all T. gondii surface proteins characterized so far. Here we describe a detailed structural analysis of this anchor. GPI anchor peptides were isolated from [3H]glucosamine labeled purified P30 by protease digestion and phase partitioning. Neutral glycans were prepared from this material by dephosphorylation and deamination. Two glycoforms were characterized by gel filtration and high performance ion exchange chromatography in combination with exoglycosidase treatment. Both forms were shown to carry an N-acetylgalactosamine bound to the first mannose of the conserved three-mannosyl core. Glycan B carries an additional terminal hexose linked to GalNAc. To identify the nature of this hexose, bulk anchor peptide was prepared and glycans were purified by aminopropyl-HPLC. Highly purified glycans were subjected to MALDI-TOF-MS and, after derivatization, to FAB-MS and methylation linkage analysis. The structures of the two anchors found on SAG1 were determined to be: Man-alpha1,2-Man-alpha1,6-Man-[GalNAc-beta1,4-]-alpha1,4-GlcN-PI and Man-alpha1,2-Man-alpha1,6-Man [Glc-alpha1,4-GalNAc-beta1,4-]-alpha1,4-GlcN-PI. Comparison of these structures with free GPI glycolipid precursors characterized in T. gondii suggests that core modification of the anchor takes place prior to transfer to the protein.

Negative ion chemical ionization GC/MS-MS analysis of dialkylphosphate metabolites of organophosphate pesticides in urine of non-occupationally exposed subjects

Low level exposure to organophosphate (OP) pesticides can be determined by the measurement of dialkylphosphate (DAP) metabolites in urine. An analytical method is presented here which can measure the metabolites dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP) at low levels. This was achieved by lyophilization of the urine, derivatization with pentafluorobenzyl bromide (PFBBr) and quantification by negative ion chemical ionization GC/MS-MS. The detection limits for the metabolites were 0.5 microg L(-1) DMP, 0.1 microg L(-1) DEP, 0.1 microg L(-1) DMTP, 0.04 microg L(-1) DMDTP, 0.04 microg L(-1) DETP and 0.02 microg L(-1) DEDTP. The RSD for the analytical method was 4-14% for the six metabolites. The method was used to monitor a group of non-occupationally exposed individuals in Sydney, Australia. The metabolites DMP, DEP, DMTP, DMDTP, DETP and DEDTP occurred in 73, 77, 96, 48, 100 and 2% of the samples with median values of 13, 3, 12, <1, 1 and 1 microg L(-1) respectively. The method is simple to use, sensitive and suitable for routine analysis of non-occupational exposure levels. These detection limits are between one and two orders of magnitude lower than those previously reported in the literature.

Structural analysis of glycolipids from Borrelia burgdorferi

In this study the lipids of Borrelia burgdorferi, the causative agent of Lyme disease, were analyzed. Lipids comprise about 25-30% of the cell dry weight. The lipid fraction could be separated by HPTLC into 11 components. Staining of these components revealed two glycolipids and two phospholipids. The glycolipids represented about 50% of the total lipids and comprised only galactose as monosaccharide constituents. By means of mass spectrometric and gas chromatographic analysis both glycolipids could be identified as alpha-galactosyl-diacylglycerolipids with different fatty acid compositions. The phospholipids were identified as phosphatidylcholine and phosphatidylglycerol. Immunoassays with sera from patients with Lyme disease showed antibody reactivity only to the glycolipids, which was present in all stages of the disease. Other lipid components seemed to be non-immunogenic in Lyme disease. The glycolipids of B. burgdorferi may be, thus, considered promising candidates for diagnosis and possibly also for vaccination.

Characterization of N-glycans from mouse brain neural cell adhesion molecule

The N-glycosylation pattern of the neural cell adhesion molecule (NCAM), isolated from brains of newborn mice, has been analyzed. Following digestion with trypsin, generated glycopeptides were fractionated by serial immunoaffinity chromatography using immobilized monoclonal antibodies specifically recognizing polysialic acid (PSA) units or the HNK1-carbohydrate epitope. Subsequent analyses of the resulting (glyco)peptides by Edman degradation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) revealed polysialylated glycans to be exclusively linked to glycosylation sites 5 (Asn(431)) and 6 (Asn(460)), whereas glycans carrying the HNK1-epitope could be assigned to sites 2 (Asn(297)), 5, 6, and, to a lesser extent, site 3 (Asn(329)). PSA-, HNK1-, and non-PSA/HNK1-glycan fractions were characterized by carbohydrate constituent and methylation analyses as well as MALDI-TOF-MS in conjunction with chromatographic fractionation techniques. The results revealed that the core structures of PSA-glycans represented predominantly fucosylated, partially sulfated 2,6-branched isomers of triantennary as well as tetraantennary complex-type glycans, whereas carbohydrate chains bearing the HNK1-epitope were dominated by diantennary species carrying in part bisecting GlcNAc residues. Non-PSA/HNK1-glycans exhibited a highly heterogeneous pattern of partially truncated, mostly diantennary structures being characterized by the presence of additional fucose, bisecting GlcNAc and/or sulfate residues. In conclusion, our results revealed that the glycosylation pattern of murine NCAM displays high structural and regional selectivity, which might play an important role in controlling the biological activities of this molecule.

Routine gas chromatographic determination of dialkylphosphate metabolites in the urine of workers occupationally exposed to organophosphorus insecticides

A routine gas chromatographic (GC) method is described for the analysis of dialkylphosphate metabolites in the urine of workers occupationally exposed to organophosphorus insecticides. The procedure involves derivatizing a freeze-dried urine sample with pentafluorobenzyl bromide and then determining the metabolites using dual capillary column GC with flame photometric detection.

Permanent low-activity (125)I seed placement for the treatment of pediatric brain tumors: preliminary experience

Although external beam radiation therapy is effective in the treatment of many pediatric brain neoplasms its use in this patient population has been associated with the development of significant cognitive and endocrine dysfunction and is severely limited as an option in previously irradiated patients. Therefore, we have adopted a strategy for management of residual microscopic disease by implantation of low-activity (125)I seeds in the tumor bed at the time of surgery. Six patients aged 2-14 years with recurrent tumors including two supratentorial primitive neuroectodermal tumors (n = 2), one medulloblastoma, one malignant ependymoma (n = 1), glioblastoma (n = 1) and one pleomorphic xanthoastrocytoma were implanted at the time of reoperation. A total of 11-126 seeds were implanted resulting in total doses of 16-21.8 Gy (after theoretical infinite time) at a depth of 5 mm from the implanted resection bed. Five patients had prior external beam radiation while the other patient (2 years old at initial diagnosis) progressed after surgery and chemotherapy. Two patients had lasting local tumor control. One patient is alive at 390 weeks of follow-up and another who died of distant failure at 366 weeks had no recurrence on MRI at 333 weeks' follow-up. Only 2 patients had first local failures. These results suggest that the use of permanent low-activity (125)I seeds as an adjunct to surgery can provide good local tumor control and is a suitable treatment option for pediatric patients.

Glycoinositolphosphosphingolipids (basidiolipids) of higher mushrooms

The basidiolipids of six mushroom species, i.e. the basidiomycetes Amanita virosa (engl., death cup), Calvatia exipuliformis (engl., puffball), Cantharellus cibarius (engl., chanterelle), Leccinum scabrum (engl., red birch boletus), Lentinus edodes (jap., Shiitake), and Pleurotus ostreatus (engl., oystermushroom), were isolated, and their chemical structures investigated. All glycolipids are structurally related to those of the Agaricales (engl., field mushroom). They are glycoinositolphosphosphingolipids, their ceramide moiety consisting of t18:0-trihydroxysphinganine and an alpha-hydroxy long-chain fatty acid. In contrast to a previous study [Jennemann, R., Bauer, B.L., Bertalanffy, H., Geyer, R., Gschwind, R.M., Selmer, T. & Wiegandt, H. (1999) Eur. J. Biochem. 259, 331--338], the glycoside anomery of the hexose (mannose) connected to the inositol of all investigated basidiomycete glycolipids, including the basidiolipids of Agaricus bisporus, was determined unequivocally to be alpha. Therefore, the root structure of all basidiolipids consists of alpha-DManp-2Ins1-[PO(4)]-Cer. In addition, for some mushroom species, the occurrence of an inositol substitution position variant, alpha-Manp-4Ins1-[PO(40]-Cer, is shown. The carbohydrate of chanterelle basidiolipids consists solely of mannose, i.e. Cc1, Man alpha-3 or -6Man alpha; Cc2, Man alpha-3(Man alpha-6)Man alpha-. All other species investigated show extension of the alpha-mannoside in the 6-position by beta-galactoside, which, in some instances, is alpha-fucosylated in 2-position (Fuc alpha-2)Gal beta-6Man alpha-. Further sugar chain elongation at the beta-galactoside may be in 3- and/or 6-position by alpha-galactoside, e.g. Ce4, Po2, Gal alpha-3-(Gal alpha-6)(Fuc alpha-2)Gal beta-6Man alpha-, whereas A. virosa, Av-3, has a more complex, highly alpha-fucosylated terminus, Gal alpha-3 (Fuc alpha-2)(Fuc alpha-6)Gal alpha-2(Gal alpha-3)Gal beta-6Man alpha-. L. edodes basidiolipids show further elongation by alpha-mannoside, e.g. Le3, Man alpha-2Man alpha-6Gal alpha-3(Fuc alpha-2)Gal beta-6Man alpha-, C. exipuliformis glycolipid by alpha-glucoside, i.e. Ce3, Glc alpha-6Gal beta-6Man alpha-. Basidiolipid Ls1 from L. scabrum, notably, has a 3-alpha-mannosylated alpha-fucose, i.e. Gal alpha-6(Man alpha-3Fuc alpha-2)Gal alpha-6Gal beta-6Man alpha-. In conclusion, basidiolipids, though identical in their ceramide constitution, display wide and systematic mushroom species dependent variabilities of their chemical structures.

Immunohistochemical localization and differentiation of phosphocholine-containing antigens of the porcine, parasitic nematode, Ascaris suum

The glycolipids of Ascaris suum represent either neutral, zwitterionic or acidic structures. The acidic fraction comprises a sulphatide and an unusual phosphoinositolglycosphingolipid (Lochnit et al. 1998b). The sulphatide was previously localized to the hypodermis, contractile zone of somatic muscle cells and the external musculature of the female uterus, whereas the presence of the phosphoinositolglycosphingolipid species was restricted to the intestine. The neutral and zwitterionic components belong to the arthro-carbohydrate series, which are substituted in their zwitterionic structures by phosphocholine (PC) and in one glycolipid by an additional phosphoethanolamine residue. In previous immunohistochemical localization studies, however, the chemical nature of the PC-substituted biomolecules has not been investigated in detail. Here, we report on the immunohistochemical localization and differentiation of phosphocholine-containing structures into lipid- and protein-bound species in adult A. suum. The patterns of immunostaining, obtained with a PC-specific monoclonal antibody and anti-zwitterionic glycolipid hyperimmune serum in the female worm, indicated a parallel organ distribution for glycolipid- and protein-bound PC-epitopes. Immunoreactivity was localized to specific tissues of the body wall, intestine and reproductive tract. This is the first report of surface-located PC-epitopes for ascarids. The patterns of immunolabelling obtained with antibodies directed against the unsubstituted arthro-carbohydrate series backbone suggested that the glycolipid-bound epitope was restricted to the hypodermis, whilst the protein-bound antigenic determinant resembled that for PC.

Structural and Functional Stability of the Mature Transferrin Receptor from Human Placenta

The transferrin receptor (TfR) is a N- and O-glycosylated transmembrane protein mediating the cellular iron uptake by binding and internalization of diferric transferrin. In this study, rate constants and dissociation constants of 125I-ferri-transferrin binding to the human TfR were examined dependent on receptor glycan composition, pH, bivalent cations, and temperature. To do so, purified human placental TfR was noncovalently immobilized to polystyrene surfaces and subjected to alterations in various parameters. We found that transferrin binding was clearly dependent on a receptor pretreatment with buffers of various pH in that most of the TfR molecules irreversibly lost transferrin binding activity below pH 6.5. However, the dissociation constant of the remaining active binding sites was not affected. Similarly, we were able to define the thermal stability of the receptor as a function of transferrin binding ability. Binding of transferrin was completely lost provided that the receptor was pretreated at temperatures of at least 65 degrees C. Treatment with EDTA also caused an irreversible loss of transferrin binding activity, indicating that the functionally active conformation of the mature TfR depends on bivalent cations. In order to examine the role of the receptor glycans, we enzymatically removed the sialic acid residues, the hybrid and oligomannosidic N-glycans, or all types of N-glycans. In contrast to the parameters described above, all desialylated and N-deglycosylated TfR variants had exactly the same transferrin binding properties as the native TfR. To assess changes in the secondary structure of the receptor, circular dichroic spectra were recorded from TfR at pH 5.0, from heat pretreated receptor and from deglycosylated TfR. Since the receptor did not exhibit detectable changes in the CD spectrum of the deglycosylated receptor, it can be concluded that the N-linked carbohydrates of the mature, fully processed TfR are not essential for transferrin binding and conformational stability.

The liver flukes Fasciola gigantica and Fasciola hepatica express the leucocyte cluster of differentiation marker CD77 (globotriaosylceramide) in their tegument

Glycosphingolipids from the parasitic liver flukes Fasciola gigantica and Fasciola hepatica were isolated and their carbohydrate moieties were structurally analysed by methylation analysis, exoglycosidase treatment, on-target exoglycosidase cleavage and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. For both liver fluke species, the ceramide monohexosides Gal1-ceramide and Glc1-ceramide were found in relative amounts of 1.0 to 0.1, respectively. From F. gigantica, the ceramide dihexoside was isolated in sufficient amounts to be structurally determined as lactosylceramide, Gal beta4-Glc1-ceramide, while for both liver fluke species the ceramide trihexoside was shown to be Gal alpha4Gal beta4-Glc1-ceramide, which is designated as either globotriaosylceramide, Pk-blood group antigen or CD77 leucocyte cluster of differentiation antigen. To our knowledge, this is the first report on the expression of globo-series glycosphingolipids in non-mammalian species. Ceramide analysis of ceramide monohexosides yielded as major components octadecanoic and 2-hydroxyoctadecanoic fatty acids together with C18- and C20-phytosphingosines. By the use of an anti-CD77 monoclonal antibody and the Escherichia coli Shiga toxin B1 subunit, globotriaosylceramide could be immunolocalised to the tegument of F. hepatica cryosections. The sharing of CD77 between liver flukes and their mammalian hosts fits in with the concept of molecular mimicry, which is closely parallel to the established imitation of host CD15 (Lewis X) displayed by the blood fluke Schistosoma mansoni.

Growth hormone replacement therapy in children with medulloblastoma: use and effect on tumor control

PURPOSE

Progress has been made in the treatment of medulloblastoma, the most common childhood malignant brain tumor: However, many long-term survivors will have posttherapy growth hormone insufficiency with resultant linear growth retardation. Growth hormone replacement therapy (GHRT) may significantly improve growth, but there is often reluctance to initiate GHRT because of concerns of an increased likelihood of tumor relapse.

PATIENTS AND METHODS

This study retrospectively reviewed the use of GHRT for survivors of medulloblastoma in 11 neuro-oncology centers in North America who received initial treatment for disease between 1980 and 1993 to determine its impact on disease control. A Landmark analysis was used to evaluate the relative risk of relapse in surviving patients.

RESULTS

Five hundred forty-five consecutive patients less than 15 years of age at diagnosis were identified. Six-year progression-free survival (mean +/- SD) was 40% +/- 5% in children less than 3 years of age at diagnosis compared with 59% +/- 3% for older patients. Older patients with total or near-total resections (P = .003) and localized disease at diagnosis (P < .0001) had the highest likelihood of survival. One hundred seventy patients (33% +/- 3% of the cohort) received GHRT. GHRT use varied widely among institutions, ranging from 5% to 73%. GHRT was begun a mean of 3.9 years after diagnosis, later in children younger than 3 years at diagnosis (5.4 years). By Landmark analyses, for those surviving 2, 3, and 5 years after diagnosis, there was no evidence that GHRT increased the rate of disease relapse.

CONCLUSION

This large retrospective review demonstrates that GHRT is underutilized in survivors of medulloblastoma and is used relatively late in the course of the illness. GHRT is not associated with an increased likelihood of disease relapse.