Serum-Stable and Selective Backbone-N-Methylated Cyclic Peptides That Inhibit Prokaryotic Glycolytic Mutases

N-Methylated amino acids (N-MeAAs) are privileged residues of naturally occurring peptides critical to bioactivity. However, de novo discovery from ribosome display is limited by poor incorporation of N-methylated amino acids into the nascent peptide chain attributed to a poor EF-Tu affinity for the N-methyl-aminoacyl-tRNA. By reconfiguring the tRNA's T-stem region to compensate and tune the EF-Tu affinity, we conducted Random nonstandard Peptides Integrated Discovery (RaPID) display of a macrocyclic peptide (MCP) library containing six different N-MeAAs. We have here devised a "pool-and-split" enrichment strategy using the RaPID display and identified N-methylated MCPs against three species of prokaryotic metal-ion-dependent phosphoglycerate mutases. The enriched MCPs reached 57% N-methylation with up to three consecutively incorporated N-MeAAs, rivaling natural products. Potent nanomolar inhibitors ranging in ortholog selectivity, strongly mediated by N-methylation, were identified. Co-crystal structures reveal an architecturally related Ce-2 Ipglycermide active-site metal-ion-coordinating Cys lariat MCP, functionally dependent on two cis N-MeAAs with broadened iPGM species selectivity over the original nematode-selective MCPs. Furthermore, the isolation of a novel metal-ion-independent Staphylococcus aureus iPGM inhibitor utilizing a phosphoglycerate mimetic mechanism illustrates the diversity of possible chemotypes encoded by the N-MeAA MCP library.

SU-E-T-125: High-Resolution Linear Diode Array for Use in Stereotactic Beam Commissioning

PURPOSE

Task Group 106 discusses detector arrays and their usefulness in "soft-wedge" profile measurements. This study verifies an extension of their use; where a high-resolution linear diode array is used to measure profile scans for use in commissioning stereotactic beam. Small-field data is acquired with the LDA-99sc (IBA Dosimetry America, Memphis, TN), an array of 99 two-mm-diameter Hi-pSi diodes. These data are compared to data collected during serial scanning with an IBA SFD stereotactic diode.

METHODS

Field measurements were taken at varying depths using an LDA-99sc in 1×1 cm² , 2×2cm² , and 3×3cm² fields of a Trilogy accelerator (Varian Medical Systems, Palo Alto, CA). These scans were duplicated in resolution and sample rate with an SFD scanning diode. Both techniques acquired point data in 1.0mm increments.

RESULTS

In identical conditions, the LDA-99sc provided readings with significantly less signal fluctuation than with traditional diode scanning; which is attributed to the reduction of water motion associated with detector travel during traditional scanning. This smoother data precluded the use of smoothing and filtration algorithms; allowing the beam to be modeled using raw data. The LDA-99sc measured an average penumbra of 0.1 mm wider than that which was measured with the diode. The LDA-99sc also measured an average field size of 0.3mm wider than that which was measured with the diode. With respect to time, a single profile scan (30cm-depth, 3×3cm² field) using the LDA-99sc took 31 seconds, while a diode scan took 229 seconds.

CONCLUSIONS

The LDA99 provided accurate commissioning-grade small-field beam profile data, as verified by comparison with diode scans, with a reduction of uncertainty in readings and a substantial reduction in time. Variation in penumbra and beam widths were deemed acceptable and can be attributed to the LDA-99sc data being raw, while the diode data was processed. Research supported in-part by IBA Dosimetry America.

A single agent, phase I pharmacodynamic study of nimotuzumab (TheraCIM-h-R3) in patients with advanced refractory solid tumors

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Background: Nimotuzumab (N) is a humanized mAb against the EGFR extracellular ligand binding domain. Although well tolerated when combined with radiotherapy in previous studies and lacking usual toxicities of EGFR-targeting agents, the pharmacodynamics (PD) of N has not been elucidated. This phase I study was designed to evaluate the safety, tolerability and PD of N. Methods: Eligibility criteria included advanced solid tumors refractory to standard therapy and ECOG PS = 0 - 2. IV N was administered weekly x 6 and then every other week (6 weeks = 1 treatment cycle). Tumor, skin and liver biopsies obtained pre- and 2 and 7 weeks post-treatment were evaluated using computer-based, whole mount assessment of immunohistochemical staining. Results: Accrual was completed 21/09/06, 17 patients (11m/6f, median age 63, 13 colorectal cancer, ECOG 0:1:2 = 6:10:1, prior therapy 1:2:3+ = 2:6:9) were registered and 16 patients were treated on 4 dose levels (100, 200, 400 and 800 mg) for a total of 43 treatment cycles (1 patient deemed ineligible after registration did not receive study therapy). Treatment was well tolerated. One dose-limiting toxicity was observed (dose level 1 - grade 3 fatigue possibly attributable to N) . Skin toxicity was mild (Gr 1/2 in 7/1 patients). Confirmed stable disease was seen in 6 patients, a confirmed partial response in 1 patient with prolonged progression-free status observed in 3 patients for 5.8, 14.1 and 18.7 months (the latter two remain on study). Baseline and week 2 biopsies of tumor/skin/liver were evaluable in 12/13/7 pts. Week 7 tumor/skin/liver biopsies in initially responding or stable patients were evaluable in 6/8/6 pts. Post treatment (week 2), EGFR staining decreased in 8/12 matched tumor [mean ratio (post/pre): 0.79 range: (0.37, 1.91)], 8/13 skin [0.96 (0.40, 1.31)] and 5/7 liver [0.88 (0.62, 1.17)] biopsies. No significant relationship was detected between pre/post-treatment EGFR expression with either response or toxicity. Evaluation of downstream targets of EGFR (in tumor, skin and liver) is ongoing and will be presented. Conclusions: Overall nimotuzumab was well tolerated and exhibits mild skin toxicity. Prolonged progression free-survival was observed in 3/16 of these heavily pre-treated patients.

No significant financial relationships to disclose.

Manipulating Enteric Methane Emissions and Animal Performance of Late-Lactation Dairy Cows Through Concentrate Supplementation at Pasture

The objective of this study was to determine the potential of increased fiber-based concentrates to reduce methane (CH(4)) production in relation to milk yield from late-lactation dairy cows. The effect of 2 levels of concentrate supplementation (0.87 vs. 5.24 kg on a dry matter basis) on herbage voluntary intake, total dry matter intake, milk yield, milk composition, and CH(4) production were determined by way of a randomized block designed grazing trial using lactating Holstein-Friesian cows (231 +/- 44 d in milk) grazing a mixed-grass sward with a regrowth aged 36 d. Increased concentrate supplementation resulted in a significant increase in total dry matter intake, milk yield, fat-corrected milk (FCM) yield, and daily CH(4) production. However, herbage intake and milk composition were unaffected. Although daily CH(4) production increased with fibrous concentrate use the increase was not as great as that observed for milk yield. The decline in CH(4) production per kilogram of milk was nonsignificant; however, when relating CH(4) production to FCM(FCM at 35 g of fat/kg of milk), a declining trend was identified within increasing concentrate supplementation (19.26 and 16.02 g of CH(4)/kg of FCM). These results suggest that increased fibrous concentrate use at pasture, even at modest levels, could reduce enteric CH(4) production per kilogram of animal product. However, the effectiveness of such a strategy is dependent on the maintenance of production quotas and a subsequent decline in the number of livestock needed to fulfill the specified production level.

Protonation and deprotonation of TpOs(NHPh)Cl(2): an unusually inert amido ligand

Protonation of the Os(IV) amido complex TpOs(NHPh)Cl(2) (1) to give the aniline complex [TpOs(NH(2)Ph)Cl(2)]OTf (2) requires excess triflic acid (HOTf). Complex 1 is unreactive with HCl and other moderately strong acids. Consistent with the low basicity of 1, the aniline complex 2 is extremely acidic and is deprotonated by stoichiometric addition of weak bases such as Cl(-) or H(2)O. No reaction is observed between 1 and methyl triflate (CH(3)OTf) at ambient temperatures. Upon heating, CH(3)OTf removes the chloride ligands from 1 to give CH(3)Cl and the amidobis(triflate) complex TpOs(NHPh)(OTf)(2) (3). Attack at the amido nitrogen is not observed. Complex 1 is thus very inert to protonation and electrophilic attack at nitrogen. A deprotonated form of 1, TpOs[NPh(MgBr)]Cl(2) (4), is generated on reaction of PhMgBr with TpOs(N)Cl(2). Complex 4 is extremely basic and will protonate to 1 with weak acids such as CH(3)CN, DMSO, and acetic anhydride. Thus, 1 has a low acidity as well as a low basicity; it is both less acidic and less basic than aniline. The inertness of 1 is ascribed to partial Os-N pi bonding and to the oxidizing nature of the Os(IV) center.

C--N bond formation on addition of aryl carbanions to the electrophilic nitrido ligand in TpOs(N)Cl(2)

The osmium(VI) nitrido complex TpOs(N)Cl(2) (1) has been prepared from K[Os(N)O(3)] and KTp in aqueous ethanolic HCl. It reacts rapidly with PhMgCl and related reagents with transfer of a phenyl group to the nitrido ligand. This forms Os(IV) metalla-analido complexes, which are readily protonated to give the analido complex TpOs(NHPh)Cl(2) (4). The nitrido-phenyl derivatives TpOs(N)PhCl and TpOs(N)Ph(2) react more slowly with PhMgCl and are not competent intermediates for the reaction of 1 with PhMgCl. Reactions of 1 with alkyl- and arylboranes similarly result in transfer of one organic group to nitrogen, leading to isolable borylamido complexes such as TpOs[N(Ph)(BPh(2))]Cl(2) (11). This is an unprecedented insertion of a nitrido ligand into a boron--carbon bond. Hydrolysis of 11 gives 4. Mechanistic studies suggest that both the Grignard and borane reactions proceed by initial weak coordination of Mg or B to the nitrido ligand, followed by migration of the carbanion to nitrogen. The hydrocarbyl group does not go to osmium and then move to nitrogen--there is no change in the atoms bound to the osmium during the reactions. It is suggested that there may be a general preference for nucleophiles to add directly to the metal--ligand multiple bond rather than binding to the metal first and migrating. Ab initio calculations show that the unusual reactivity of 1 results from its accessible LUMO and LUMO + 1, which are the Os = N pi* orbitals. The bonding in 1 and its reactivity with organoboranes are reminiscent of CO.

National survey of hepatitis testing and vaccination services provided by drug services in England and Wales

Since viral hepatitis among intravenous drug users continues to be a major cause of morbidity and mortality, the present study was conducted to survey drug agencies in England and Wales in order to identify the prevalence of hepatitis B and C testing and vaccination being provided. A postal survey of all 539 drug agencies in England and Wales was thus conducted to assess their current treatment provisions and practices. An analysis of the responses provided by the 373 agencies that returned usable data (69.2% response rate) revealed that only one-quarter (26.6%) of the drug agencies conducted routine hepatitis B testing, and 26.9% did not offer it at all. Just over half (55.7%) of the agencies provided hepatitis B vaccination, but only 21.7% did so routinely. Seventy percent provided hepatitis C testing, but only 24% did so routinely. Nevertheless, the majority of respondents, of whom 40.3% were nurses and 25.1% drug workers, believed that clients and their partners should be offered hepatitis B and C screening. The paucity of hepatitis testing and vaccination services being offered to injecting drug users is unacceptable, with users, their partners and children being needlessly exposed to continued risk. The disparity between recommended policy and current practice needs to be urgently addressed.

Pharmacy-based needle exchange (PBNX) schemes in south east England: a survey of service providers

AIMS

To describe the activities of service providers with regard to (i) the business operation and policies defining pharmacy-based needle exchange (PBNX) in South East England; (ii) the day-to-day work of PBNX outlets from the provider perspective; and (iii) problems encountered by PBNX providers.

DESIGN

(i) Postal self-completion questionnaire to all participating PBNX community pharmacies in South East England; and (ii) postal self-completion questionnaire to needle exchange coordinators.

SETTING

Community pharmacy needle exchanges.

PARTICIPANTS

Pharmacists in charge of needle exchange; and needle exchange coordinators.

FINDINGS

Data were collected (i) from 381/440 (86.7%) participating community pharmacists, and (ii) 32/36 (88.9%) of coordinators. The study found that PBNX was reaching injecting drug users (many of whom used PBNX regularly), and providing a wide range of injecting equipment. Although pharmacists reported that problems such as shoplifting occurred relatively frequently, more serious problems such as violence were relatively rare. However, PBNX pharmacists reported needing further training for themselves and their staff. Suggested improvements included better advertising of services and improving returns rates for used injecting equipment.

CONCLUSION

Needle exchange can reasonably be provided by non-specialist health care professionals such as community pharmacists. However, attention should to be paid to the educational needs of service providers who also require adequate support.

Irinotecan therapy in adults with recurrent or progressive malignant glioma

PURPOSE

To determine the activity, toxicity, and pharmacokinetics of irinotecan (CPT-11, Camptosar; Pharmacia & Upjohn, Kalamazoo, MI) in the treatment of adults with progressive, persistent, or recurrent malignant glioma.

PATIENTS AND METHODS

Patients with progressive or recurrent malignant gliomas were enrolled onto this study between October 1996 and August 1997. CPT-11 was given as a 90-minute intravenous (i.v.) infusion at a dose of 125 mg/m2 once weekly for 4 weeks followed by a 2-week rest, which comprised one course. Plasma concentrations of CPT-11 and its metabolites, SN-38 and SN-38 glucuronide (SN-38G), were determined in a subset of patients.

RESULTS

All 60 patients who enrolled (36 males and 24 females) were treated with CPT-11 and all were assessable for toxicity, response, and survival. Pharmacokinetic data were available in 32 patients. Nine patients (15%; 95% confidence interval, 6% to 24%) had a confirmed partial response, and 33 patients (55%) achieved stable disease lasting more than two courses (12 weeks). Toxicity observed during the study was limited to infrequent neutropenia, nausea, vomiting, and diarrhea. CPT-11, SN-38, and SN-38G area under the plasma concentration-time curves through infinite time values in these patients were approximately 40%, 25%, and 25%, respectively, of those determined previously in patients with metastatic colorectal cancer not receiving antiepileptics or chronic dexamethasone treatment.

CONCLUSION

Response results document that CPT-11, given with a standard starting dose and treatment schedule, has activity in patients with recurrent malignant glioma. However, the low incidence of severe toxicity and low plasma concentrations of CPT-11 and SN-38 achieved in this patient population suggest that concurrent treatment with anticonvulsants and dexamethasone enhances drug clearance.

DNA mismatch repair and O6-alkylguanine-DNA alkyltransferase analysis and response to Temodal in newly diagnosed malignant glioma

PURPOSE

We evaluated the response to Temodal (Schering-Plough Research Institute, Kenilworth, NJ) of patients with newly diagnosed malignant glioma, as well as the predictive value of quantifying tumor DNA mismatch repair activity and O6-alkylguanine-DNA alkyltransferase (AGT).

PATIENTS AND METHODS

Thirty-three patients with newly diagnosed glioblastoma multiforme (GBM) and five patients with newly diagnosed anaplastic astrocytoma (AA) were treated with Temodal at a starting dose of 200 mg/m2 daily for 5 consecutive days with repeat dosing every 28 days after the first daily dose. Immunochemistry for the detection of the human DNA mismatch repair proteins MSH2 and MLH1 and the DNA repair protein AGT was performed with monoclonal antibodies and characterized with respect to percent positive staining.

RESULTS

Of the 33 patients with GBM, complete responses (CRs) occurred in three patients, partial responses (PRs) occurred in 14 patients, stable disease (SD) was seen in four patients, and 12 patients developed progressive disease (PD). Toxicity included infrequent grades 3 and 4 myelosuppression, constipation, nausea, and headache. Thirty tumors showed greater than 60% cells that stained for MSH2 and MLH1, with three CRs, 12 PRs, three SDs, and 12 PDs. Eight tumors showed 60% or less cells that stained with antibodies to MSH2 and/or MLH1, with 3 PRs, 3 SDs, and 2 PDs. Eleven tumors showed 20% or greater cells that stained with an antibody to AGT, with 1 PR, 2 SDs, and 8 PDs. Twenty-five tumors showed less than 20% cells that stained for AGT, with 3 CRs, 12 PRs, 4 SDs, and 6 PDs.

CONCLUSION

These results suggest that Temodal has activity against newly diagnosed GBM and AA and warrants continued evaluation of this agent. Furthermore, pretherapy analysis of tumor DNA mismatch repair and, particularly, AGT protein expression may identify patients in whom tumors are resistant to Temodal.

Treatment of adults with progressive oligodendroglioma with carboplatin (CBDCA): preliminary results. Writing Committee for The Brain Tumor Center at Duke

BACKGROUND

Exploration of the role of chemotherapy in the treatment of low grade glioma, including oligodendroglioma, has been limited to the pediatric population, reflecting the sensitivity of young patients to radiation-induced toxicity and a desire to avoid this intervention (7-12).

PROCEDURE

Nine adults with progressive oligodendroglioma were treated with carboplatin at a dose of 560 mg/m2 administered at 4 week intervals.

RESULTS

Eight patients have demonstrated stable disease as determined by serial MRI imaging at 2-3 month intervals with neither tumor regression nor growth noted. The ongoing duration of tumor control ranges between 6-22 months. Three patients have completed therapy with carboplatin and continue with stable dis-ease off chemotherapy. One patient progressed after 1 year of therapy with histologic confirmation of growth of well differentiated oligodendroglioma. Toxicity was limited to grade 3 thrombocytopenia in 3 patients and grade 3 neutropenia in 2 patients.

CONCLUSIONS

Carboplatin appears to be active in the treatment of adults with progressive oligodendroglioma. Further trials are warranted to more precisely define the role of carboplatin in the treatment of these tumors.

Phase II study of carboplatin (CBDCA) in progressive low-grade gliomas

In this study, the authors sought to investigate the response rate and toxicity of carboplatin in patients with progressive low-grade glioma (LGG). Thirty-two patients with progressive LGG were treated with carboplatin at a dosage of 560 mg/m2. Treatment was given at 4-week intervals and continued until the disease progressed, unacceptable toxicity supervened, or for 12 additional courses after achieving maximal response. Patients with stable disease were treated with a total of 12 cycles. All patients were treated as outpatients. Patients were evaluated for response to treatment and toxicity.

All patients received a minimum of two cycles of carboplatin, and were examined for response. A partial response was achieved in nine patients (28%) and a minimal response in two (6%), for an overall response rate of 34% (11 of 32 patients). Eighteen patients (56%) had stable disease. A partial response was achieved in the nine patients after a median of six cycles (range 4-11 cycles), a minimal response was achieved in the two patients after five cycles. Glioma progression was noted in three patients after three, five, and five cycles, respectively. The 11 patients in whom some response was achieved had either an optic pathway tumor or a juvenile pilocytic astrocytoma. Twenty-six of the 32 patients had those characteristics, making the response rate in that group 42% (11 of 26 patients). Thirty-two patients received a total of 387 cycles of chemotherapy. Hematological toxicity was moderate. Twenty-one patients developed thrombocytopenia (platelet count < 50,000/μl); three patients required one platelet transfusion each. Nine patients developed neutropenia (absolute neutrophil count < 500/μl); one developed fever and required administration of antibiotic agents. One dose adjustment in each of the patients prevented further thrombocytopenia and neutropenia. Two patients with stable disease died of respiratory complications. One patient developed Grade III ototoxicity after receiving five cycles, one patient developed hypersensitivity to carboplatin, and none developed nephrotoxicity.

Carboplatin given at a dosage of 560 mg/m2 every 4 weeks has activity in patients with progressive LGG. This drug regimen is relatively simple and well tolerated. Further investigation and longer follow-up study are warranted.

Ecstasy: 3,4-methylenedioxymethamphetamine (MDMA)

The crystal structure of 3,4-methylenedioxymethamphetamine [systematic name: N-methyl-1-[3,4-(methylenedioxy) phenyl]-2-aminopropane] hydrochloride, C11H15NO2.HCl, also known as 'ecstasy' or MDMA, has been determined by X-ray diffraction.

Evaluation of chemicals with endocrine modulating activity in a yeast-based steroid hormone receptor gene transcription assay

There is a concern that chemicals in our environment are affecting human health by disrupting normal endocrine function. Much of the concern has focused on chemicals that can interact directly with steroid hormone receptors. We have used a yeast-based assay to assess chemical interactions with the estrogen, androgen, and progesterone receptors. The yeast transformants used in this study contained the human estrogen, androgen, or progesterone receptor along with the appropriate steroid responsive elements upstream of the beta-galactosidase reporter gene. Chemicals were added to yeast cultures in doses ranging from 10(-12) to 10(-4) M and following incubation, the yeasts were then lysed and assayed for beta-galactosidase activity. Diethylstilbesterol and 17-beta estradiol were most active in the estrogen receptor assay, followed by the phytoestrogen, coumestrol. p-Nonylphenol and bisphenol A were approximately 5000- and 15,000-fold less active, respectively, than estradiol. Methoxychlor, DDT and its metabolites, o,p'-DDD, and o,p'-DDE ranged in potency from 5 to 24 X 10(6) less potent than estradiol. Testosterone and dihydrotestosterone were most potent in the androgen receptor assay, followed by estradiol and progesterone. p,p'-DDE was approximately 10(6)-fold less potent than testosterone. None of the industrial chemicals tested interacted with the progesterone receptor. These data demonstrate the utility of using yeast-based receptor assays for detecting chemical interaction with steroid receptors and these assays should serve as a useful component of an in vitro-in vivo strategy to assess the effects of chemicals on endocrine function.

The effect of cephalothin prophylaxis on postoperative ventriculoperitoneal shunt infections

Postoperative infection is an important complication after insertion of a ventriculoperitoneal (VP) shunt in children with hydrocephalus. A randomized double-blind placebo-controlled study was performed to determine the efficacy of cephalothin in preventing postoperative shunt infection. Sixty-three children who presented for elective VP shunt insertion between January 1982 and December 1985 and who did not have a history of shunt infections were randomly assigned to receive four doses of prophylactic cephalothin, 25 mg/kg (32 patients), or of a multivitamin placebo (31 patients). Postoperative infection developed in 6% of the treatment group, compared with 10% of the placebo group, a difference that was not statistically significant, although a clinical significance may have been masked by the small sample size. A large multicentre trial is needed to determine the efficacy of antibiotic prophylaxis in reducing the incidence of postoperative VP shunt infections.

Refeeding after acute gastroenteritis: a controlled study

Children admitted with acute gastroenteritis were managed with clear fluids and then given either the standard graduated feeding regimen or an abrupt reintroduction of normal feeds. The rapid refeeding group lost less weight, went home sooner, and had no increase in complication rate. Rapid refeeding is a reasonable option in the management of acute gastroenteritis.

Food habits and nutritional status of Brisbane schoolchildren

One hundred and forty-five children, aged 11-12 years, attending a primary school in a working class suburb of Brisbane, had their weights and heights measured and answered questions about their food intakes and home backgrounds. Analyses of the data showed that children of working mothers were more likely to be overweight (greater than or equal to 110% W/H); while eating calorie dense snack foods and frequent use of the school tuckshop was associated with less underweight (less than 90% W/H), but no increase in overweight. The use of convenience foods in the home was associated with increased underweight and decreased overweight.

The natural history of chronic middle ear disease in Australian Aboriginals: a cross-sectional study

One hundred and sixty-three Australian Aboriginals, who were aged from four months to 60 years, were examined clinically and otologically. Audiometric tests were completed on 110 of these subjects. On the assumptions that the aural health of these people has remained stable for many years, the cross-sectional data which were obtained have been used to infer the natural history of ear disease. Seromucinous otitis media is manifest as a disease of early childhood, which recovers spontaneously in most cases and has no obvious sequelae. Perforated tympanic membranes likewise seem to heal spontaneously in the majority of cases. The evidence suggests that hearing loss is the main problem and treatment should be directed towards the level of hearing loss and its effects.

Infant death rates in Queensland, 1962 to 1972

Published statistical material has been used to analyse the infant death rate in Queensland. The neonatal death rates, which tend to reflect the level of obstetric care, were approximately twice as high in the Peninsula Division as in Brisbane, and the late infant mortality rate was almost eight times as high in the Peninsula Division as in Brisbane. In the Peninsula there has been no fall in infant death rate over the 11 years studied. One small area had an infant mortality rate of 100 deaths per 1,000 live births. The areas with the highest infant death rates were those with a significant Aboriginal population. The data show that proximity to major health facilities does not ensure low infant death rates and in the Brisbane Metropolitan Division there were threefold differences in late infant death rates. It seems likely that infant death rates are influenced by the economic status and education of parents and by the priority they place on infant care. The study has shown that published statistical data can detect areas within Queensland with high infant death rates, and could therfore be used to direct resources to improve the well-being of infants in these areas.

A flow calorimetric method of determining electron beam energy

The construction of an adiabatic flow calorimeter using water as the working substance is described. It is shown that at high dose rates the heat defect due to chemical reactions in water is small (of the order of 0-3%) and that under high dose rate conditions flow calorimetry can be used as a method of measuring the energy of high intensity electron beams. Measurements made with a 15 MeV linear accelerator are reported and compared with magnetic measurements.