Decisional needs in people with kidney failure, their relatives and health professionals about end-of-life care options: A qualitative interview study

AIM

To investigate the decisional needs in Denmark of people with kidney failure, relatives, and health professionals when planning end-of-life care.

DESIGN

A qualitative interview study.

METHODS

Individual semi-structured interviews were carried out with people with kidney failure, relatives and health professionals from November 2021 to June 2022. Malterud's systematic text condensation was used to analyse transcripts.

RESULTS

A total of 13 patients, 10 relatives, and 12 health professionals were interviewed. Overall, four concepts were agreed on: (1) Talking about end of life is difficult, (2) Patients and relatives need more knowledge and information, (3) Health professionals need more tools and training, and (4) Experiencing busyness as a barrier to conversations about end of life.

CONCLUSION

People with kidney failure, relatives, and health professionals shared certain decisional needs while also having some different decisional needs about end-of-life care. To meet these various needs, end-of-life conversations should be systematic and organized according to the patients' needs and wishes.

IMPACT

Non-systematic end-of-life care decision-making processes limit patients' involvement. Patients and relatives need more knowledge about end-of-life care, and health professionals need more competences and time to discuss decisional needs. A shared decision-making intervention for people with kidney failure when making end-of-life care decisions will be developed.

REPORTING METHOD

This empirical qualitative research is reported according to the Consolidated Criteria for Reporting Qualitative Research (COREQ) checklist.

PATIENT OR PUBLIC CONTRIBUTION

Patients, relatives, and health professionals have been involved throughout the research process as part of the research team and advisory board. The patients are people with kidney failure and the relatives are relatives of a person with kidney failure. For this study, the advisory board has particularly contributed to the validation of the invitation letter for participation, the interview guides and the preparation of the manuscript.

Fracture Patterns in Type 1 and Type 2 Diabetes Mellitus: A Narrative Review of Recent Literature

PURPOSE OF REVIEW

In this narrative review, we have summarized the literature on fracture risk in T1DM and T2DM with a special focus on fracture site, time patterns, glucose-lowering drugs, and micro- and macrovascular complications.

RECENT FINDINGS

T1DM and T2DM were associated with an overall increased fracture risk, with preferent locations at the hip, vertebrae, humerus, and ankle in T1DM and at the hip, vertebrae, and likely humerus, distal forearm, and foot in T2DM. Fracture risk was higher with longer diabetes duration and the presence of micro- and macrovascular complications. In T2DM, fracture risk was higher with use of insulin, sulfonylurea, and thiazolidinediones and lower with metformin use. The increased fracture risk in T1DM and T2DM concerns specific fracture sites, and is higher in subjects with longer diabetes duration, vascular complications, and in T2DM with the use of specific glucose-lowering medication.

Abstract P4-06-13: BRCA1/2 mutations identified by screening a large unselected breast cancer cohort in Sweden

Background

Treatment options for BRCA1/2 breast cancer include new therapeutic agents, such as poly (ADP-ribose) polymerase (PARP) inhibitors, which selectively target BRCA defective cells. According to current Swedish screening guidelines, eligibility for clinical BRCA1/2 hereditary mutation testing is mainly based on family history of breast or ovarian cancer and early age onset. We aimed at examining the prevalence and characteristics of BRCA1/2 mutation carriers by screening a large unselected breast cancer cohort in Sweden, and comparing our results with BRCA mutation carriers already identified through the national BRCA testing program.

Methods

Germline DNA (blood) from 5122 women diagnosed with breast cancer between 2001-2008 (LIBRO1 study) were analysed for BRCA1/2 mutations by targeted sequencing (next generation sequencing, NGS), of which 5099 samples passed quality control. All patients provided informed consent. Information on patient and tumor characteristics was collected from the LIBRO1 database. Clinical BRCA testing information was obtained from the BRCA Lab (Lund University, Sweden), which carries out mutation screening for all oncogenetic clinics in Sweden.

Multinomial logit models were used to compare tumor characteristics of BRCA1 and BRCA2 versus non-BRCA carriers. Multivariable logistic regression models were used to examine for differences between BRCA carriers identified through the national BRCA testing program and additional BRCA carriers found by sequencing the entire study population (not tested or not identified under current screening guidelines).

Results

In total, 92 (1.8%) BRCA1/2 mutation carriers were identified retrospectively by NGS. The prevalence of BRCA1/2 mutations was 1.6% (38/2363) between years 2001-2004; and 2.0% (54/2736) between years 2005-2008. After controlling for age and year of diagnosis, BRCA2 mutation carriers were in general similar to non-BRCA carriers regarding tumor characteristics (hormone receptor status, grade, tumor size and proliferation index), except for nodal involvement. BRCA1 mutation carriers, however, had more aggressive tumor characteristics than non-BRCA breast cancer patients.

Overall, 55/92 BRCA1/2 mutation carriers (59.8%) found by NGS were not already identified through the national clinical BRCA testing program. The BRCA carriers identified by clinical testing were more likely high-risk individuals, i.e. younger, less likely to have experienced menopause, and more likely to be associated with a familiar ovarian cancer compared to those not identified through clinical testing, after adjusting for year of diagnosis. A larger proportion of BRCA2 (34/42, 80%) than BRCA1 mutations (25/50, 50%) were missed by selectively testing, mainly high-risk individuals.

Conclusion

BRCA1/2 mutations were found in approximately 2.0% of unselected BC patients. Six out of ten BRCA mutation carriers were not identified through the national testing program, which follows the screening guidelines. Revised guidelines might be needed for the effective identification of BRCA1/2 germline mutations.

Citation Format: Li J, Wen SWX, Eriksson M, Kvist A, Christensen HN, Torstensson A, Easton DF, Teo S-H, Borg Å, Grönberg H, Czene K. BRCA1/2 mutations identified by screening a large unselected breast cancer cohort in Sweden [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-13.

Abstract P4-06-15: Targeted sequencing of BRCA1/2 across a large unselected breast cancer cohort in Sweden

Background

Observed BRCA1/2 mutation frequencies can vary depending on the population screened, screening criteria, founder effects, and methods used for testing. We aimed at examining BRCA1/2 germline mutations, identified through targeted sequencing, in a large unselected breast cancer population in Sweden.

Methods

Sequencing libraries of germline DNA from 5122 breast cancer patients diagnosed between 2001-2008 (LIBRO1) were prepared (48.48 Fluidigm Access Array system, Fluidigm Corp, USA) and sequenced (Next-generation sequencing [NGS], Illumina HiSeq 2500, v2 chemistry, University of Cambridge, UK). A total of 5099 samples (97.8%) passed quality control and were analysed.

BRCA1/2 carriers identified by NGS were compared with those who were already identified by clinical BRCA screening (n=418) performed by the BRCA Lab (Lund University). This unit carries out mutation screening for all oncogenetic clinics in Sweden using denaturing high performance liquid chromatography (DHPLC) and multiple ligation-dependent probe amplification (MLPA).

Results

A total of 50 BRCA1 mutation carriers were identified, of which 28 were unique pathogenic germline mutations. Frameshift insertions and deletions made up 34/50 (68%) of the BRCA1 mutations. Exon 11 harbored 33/50 (66%) of the BRCA1 mutations. The most common mutation was c.3048_3052dupTGAGA (n=8), which is a founder mutation originating from the West coast of Sweden. Three other Swedish founder mutations were also identified (c.1082_1092del [n=5], c.3626delT [n=3] and c.2475delC [n=2]). For BRCA2, 42 mutation carriers were identified; 33 unique deleterious BRCA2 mutations (27 frameshift deletions, 3 frameshift insertions, 9 truncating and 3 splice sites). More than half of the mutations (24/42, 57%) were found on exon 11. Of the 418 women who had attended clinical BRCA testing, 38 deleterious mutations were found. Our screening method confirmed 34 of these mutations, as two each of BRCA1 and BRCA2 mutations were missed, since NGS was proven unsuitable for the detection of large exon duplications. NGS did, however, identify three more carriers not previously identified by clinical testing (c.3048_3052dup, c.2577delA and c.7442delT). Overall, 55/92 BRCA1/2 mutation carriers (59.8%) identified in the present study by NGS were not clinically tested.

Conclusion

NGS is comparable with current BRCA testing tools for the identification of BRCA1/2 germline mutations, suggesting that the technology has the potential to be used in BRCA1/2 clinical testing in unselected breast cancer patients.

Citation Format: Li J, Wen SWX, Eriksson M, Kvist A, Christensen HN, Torstensson A, Easton DF, Teo S-H, Borg Å, Grönberg H, Czene K. Targeted sequencing of BRCA1/2 across a large unselected breast cancer cohort in Sweden [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-15.

Gene-panel testing of breast and ovarian cancer patients identifies a recurrent RAD51C duplication

Gene-panel sequencing allows comprehensive analysis of multiple genes simultaneously and is now routinely used in clinical mutation testing of high-risk breast and ovarian cancer patients. However, only BRCA1 and BRCA2 are often analyzed also for large genomic changes. Here, we have analyzed 10 clinically relevant susceptibility genes in 95 breast or ovarian cancer patients with gene-panel sequencing including also copy number variants (CNV) analysis for genomic changes. We identified 12 different pathogenic BRCA1, BRCA2, TP53, PTEN, CHEK2, or RAD51C mutations in 18 of 95 patients (19%). BRCA1/2 mutations were observed in 8 patients (8.4%) and CHEK2 protein-truncating mutations in 7 patients (7.4%). In addition, we identified a novel duplication encompassing most of the RAD51C gene. We further genotyped the duplication in breast or ovarian cancer families (n = 1149), in unselected breast (n = 1729) and ovarian cancer cohorts (n = 553), and in population controls (n = 1273). Seven additional duplication carries were observed among cases but none among controls. The duplication associated with ovarian cancer risk (3/590 of all ovarian cancer patients, 0.5%, P = .032 compared with controls) and was found to represent a large fraction of all identified RAD51C mutations in the Finnish population. Our data emphasizes the importance of comprehensive mutation analysis including CNV detection in all the relevant genes.

Abstract P3-09-01: BRCAsearch - results of population-based screening of BRCA1 and BRCA2 germline mutations in incident breast cancer in South Sweden

Increasing evidence supports the benefit of identifying the BRCA1 and BRCA2 germline mutation status in early breast cancer. Germline mutations in these two genes are treatment predictive for the benefit of risk reducing surgical interventions of the contralateral breast and the ovaries and fallopian tubes, in early breast cancer (Metcalf 2014; Domchek 2010). Furthermore, they may possibly also be treatment predictive for the effect of certain types of medical interventions (Tutt SABCS 2014).

In order to provide the patient with the opportunity to take BRCA test results into account already when planning primary treatment, BRCA testing and cancer genetic counseling needs to be initiated and performed early during the diagnostic and treatment related process in newly diagnosed breast cancer cases. Special attention needs to be taken to the fact that the test results may affect not only the patient, but also her or his relatives. We have observed that the clinical efficacy of BRCA-screening criteria may be surprisingly low, leaving a substantial number of BRCA-carriers undetected in spite of intense contacts with health care providers (Unpublished results).

BRCAsearch (ClinicalTrials.gov Identifier: NCT02557776) is a population based study including new invasive breast cancer cases at three hospitals in the South of Sweden. Patients are invited to perform BRCA1 and BRCA2 germline mutation analysis at time of primary treatment after written study information and written genetic counseling, irrespective of family history, age or clinical phenotype. The primary end-points of the study include the rate of BRCA mutations in newly diagnosed breast cancer in South Sweden, the fraction of patients that accept inclusion in the study, and the rate of mutation positive patients that do not fulfill clinical criteria for BRCA mutation screening. Secondary end-points include the perception among patient of the intervention and testing procedures, the types of questions the patients present during the process and psychosocial outcome among carriers and non-carriers.

In May 2016 about 400 patients have been included in the study, whereof 333 have been analyzed for BRCA germline mutations. The accrual target of the study is 500 patients, which will be reached during the fall of 2016. At the meeting, the BRCA1 and BRCA2 mutation rates will be presented, as well as the acceptance rate of the study among patients approached, and the fraction of mutation positive patients that do not fulfill current BRCA1 and BRCA2 mutation screening criteria, and whose positive mutation status therefore would have been missed if clinical selection criteria had been applied.

The results of the study will be used to define selection criteria for BRCA-mutation screening in new breast cancer cases, and the design of screening procedures with an appropriate clinical effectiveness.Increasing evidence supports the benefit of identifying the BRCA1 and BRCA2 germline mutation status in early breast cancer. Germline mutations in these two genes are treatment predictive for the benefit of risk reducing surgical interventions of the contralateral breast and the ovaries and fallopian tubes, in early breast cancer (Metcalf 2014; Domchek 2010). Furthermore, they may possibly also be treatment predictive for the effect of certain types of medical interventions (Tutt SABCS 2014).

In order to provide the patient with the opportunity to take BRCA test results into account already when planning primary treatment, BRCA testing and cancer genetic counseling needs to be initiated and performed early during the diagnostic and treatment related process in newly diagnosed breast cancer cases. Special attention needs to be taken to the fact that the test results may affect not only the patient, but also her or his relatives. We have observed that the clinical efficacy of BRCA-screening criteria may be surprisingly low, leaving a substantial number of BRCA-carriers undetected in spite of intense contacts with health care providers (Unpublished results).

BRCAsearch (ClinicalTrials.gov Identifier: NCT02557776) is a population based study including new invasive breast cancer cases at three hospitals in the South of Sweden. Patients are invited to perform BRCA1 and BRCA2 germline mutation analysis at time of primary treatment after written study information and written genetic counseling, irrespective of family history, age or clinical phenotype. The primary end-points of the study include the rate of BRCA mutations in newly diagnosed breast cancer in South Sweden, the fraction of patients that accept inclusion in the study, and the rate of mutation positive patients that do not fulfill clinical criteria for BRCA mutation screening. Secondary end-points include the perception among patient of the intervention and testing procedures, the types of questions the patients present during the process and psychosocial outcome among carriers and non-carriers.

In May 2016 about 400 patients have been included in the study, whereof 333 have been analyzed for BRCA germline mutations. The accrual target of the study is 500 patients, which will be reached during the fall of 2016. At the meeting, the BRCA1 and BRCA2 mutation rates will be presented, as well as the acceptance rate of the study among patients approached, and the fraction of mutation positive patients that do not fulfill current BRCA1 and BRCA2 mutation screening criteria, and whose positive mutation status therefore would have been missed if clinical selection criteria had been applied.

The results of the study will be used to define selection criteria for BRCA-mutation screening in new breast cancer cases, and the design of screening procedures with an appropriate clinical effectiveness.

Citation Format: Loman N, Borg Å, Henriksson K, Kristoffersson U, Kvist A, Silfverberg B, Törngren T, Brandberg Y, Nilsson M. BRCAsearch - results of population-based screening of BRCA1 and BRCA2 germline mutations in incident breast cancer in South Sweden [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-09-01.

Targeted sequencing of BRCA1 and BRCA2 across a large unselected breast cancer cohort suggests that one-third of mutations are somatic

We carried out targeted sequencing of BRCA1/2 in an unselected cohort of patients diagnosed with primary breast cancer within a population without strong founder mutations. Eleven percent of cases harbored a germline or somatic BRCA1/2 mutation, and the ratio of germline versus somatic mutation was 2 : 1. This has implications for treatment, genetic counseling, and interpretation of tumor-only testing.

Background

A mutation found in the BRCA1 or BRCA2 gene of a breast tumor could be either germline or somatically acquired. The prevalence of somatic BRCA1/2 mutations and the ratio between somatic and germline BRCA1/2 mutations in unselected breast cancer patients are currently unclear.

Patients and methods

Paired normal and tumor DNA was analyzed for BRCA1/2 mutations by massively parallel sequencing in an unselected cohort of 273 breast cancer patients from south Sweden.

Results

Deleterious germline mutations in BRCA1 (n = 10) or BRCA2 (n = 10) were detected in 20 patients (7%). Deleterious somatic mutations in BRCA1 (n = 4) or BRCA2 (n = 5) were detected in 9 patients (3%). Accordingly, about 1 in 9 breast carcinomas (11%) in our cohort harbor a BRCA1/2 mutation. For each gene, the tumor phenotypes were very similar regardless of the mutation being germline or somatically acquired, whereas the tumor phenotypes differed significantly between wild-type and mutated cases. For age at diagnosis, the patients with somatic BRCA1/2 mutations resembled the wild-type patients (median age at diagnosis, germline BRCA1: 41.5 years; germline BRCA2: 49.5 years; somatic BRCA1/2: 65 years; wild-type BRCA1/2: 62.5 years).

Conclusions

In a population without strong germline founder mutations, the likelihood of a BRCA1/2 mutation found in a breast carcinoma being somatic was ∼1/3 and germline 2/3. This may have implications for treatment and genetic counseling.

Abstract OT2-05-01: BRCAsearch: A population based prospective study on screening for BRCA1 and BRCA2 germline mutations in patients with newly diagnosed breast cancer treated in southern Sweden

The overall purpose of the study BRCAsearch is to evaluate a new method for offering mutation analysis of BRCA1 and BRCA2 to all patients with newly diagnosed breast cancer.

Patients with breast cancer in southern Sweden are offered inclusion in the SCAN-B study at the time of diagnosis pre-surgery. If they consent, a part of the tumor is sent to a lab in Lund, Sweden, for research purposes (RNA sequencing etc.). Patients that are included in the SCAN-B study are eligible for inclusion in BRCAsearch.

Summary of study procedure for BRCAsearch:

1.An envelope with written information is given to the patient at the visit to the surgeon the week after surgery. This envelope contains a written genetic counseling, information about the study, an informed consent form, psychosocial questionnaires and contact information to a genetic counsellor and psycisians responsible for the study (telephone, e-mail). The patient can contact a genetic counselor for pre-test telephone genetic counseling if she wishes to.

2.BRCA1 and BRCA2 are analyzed.

3.Non-carriers are informed about the test result with a letter. Mutation carriers and VUS (variants of uncertain significance) are telephoned and given a time for an appointment at the Department of Clinical Genetics.

4.Psychosocial self-reported questionnaires are delivered at 3 times over a year.

Inclusion criteria (all):

1.The patient is included in the SCAN-B study.

2.The patient is recently diagnosed with an invasive breast cancer or a ductal cancer in situ.

3.The patient has signed an informed consent form for BRCAsearch.

Exclusion criteria (any of):

1.The patient is unable to understand the written information in Swedish.

2.The patient is a psychological state, due to chronic och temporary reasons, where one could suspect that information about the study substantially could be detrimental to the psychological well-beeing.

Primary outcome measures:

• Prevalence of BRCA1/2 mutations in an unselected breast cancer cohort in southern Sweden

• Uptake of genetic testing

• Proportion of the mutation carriers that do not fulfil current criteria for genetic testing

Secondary outcome measures:

• How many of the patients that contact us for questions and what type of questions they have

• How uptake of genetic testing varies with patient, treatment, and tumor characteristics

• The patients' attitudes towards the method used for identifying mutation carriers

• The economic cost per QALY (quality-adjusted life year)

• Psychosocial comparisons between mutation carriers and non-carriers

Targeted accrual is 500 patients included in the study, which is expected to be reached by the end of 2016.

The study enrolls patients from two hospitals in southern Sweden:

1.Helsingborg Hospital (study start: Febuary 2, 2015)

2.Kristianstad Hospital (study start: March 2, 2015).

Citation Format: Nilsson MP, Borg Å, Henriksson K, Kristoffersson U, Kvist A, Silfverberg B, Törngren T, Loman N. BRCAsearch: A population based prospective study on screening for BRCA1 and BRCA2 germline mutations in patients with newly diagnosed breast cancer treated in southern Sweden. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT2-05-01.

P3-06-08: SCAN-B: An Accelerated Translational Pipeline from Profile to Prognosis and Prediction for Individual Breast Cancer Patients

The South Sweden Cancerome Analysis Network - Breast (SCAN-B) Initiative is a multidisciplinary network of clinical providers of breast cancer (BC) treatment and pre-clinical scientists whose multiyear purpose is to 1) prospectively collect and analyze the “-omes” of a very large, consecutive, and population-based sample of BCs for translational research; 2) utilize this genomic data to develop new clinically-relevant biomarker assays; and 3) to build the infrastructure for future real-time clinical implementation of resultant biomarkers for individualized treatment. Patient enrollment began in the Fall of 2010 at the seven BC surgical units of the South Sweden Healthcare Region, where approximately 1500 new breast cancer diagnoses are treated yearly following the guidelines of the South Sweden Breast Cancer Group. Currently, tumor and blood samples are being collected at the rate of 80–100 patients per month, which represents approximately 75% of the catchment population. SCAN-B will initially focus on tumor transcriptome analysis using mRNA-sequencing on Illumina HiSeq 2000 instruments, and in the future multimodal data generated from other genomic platforms will also be integrated. Here we present initial experiences from this multidisciplinary collaboration including descriptions of the clinical routines, specimen handling, laboratory processing, mRNA-seq data quality control, short- and long-term projects and future directions. We believe large initiatives like SCAN-B could significantly reduce the time to discovery, validation, and clinical implementation of more powerful diagnostic, prognostic, and treatment-predictive tests for breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-06-08.

Carrying large fuel loads during sustained bird flight is cheaper than expected

Birds on migration alternate between consuming fuel stores during flights and accumulating fuel stores during stopovers. The optimal timing and length of flights and stopovers for successful migration depend heavily on the extra metabolic power input (fuel use) required to carry the fuel stores during flight. The effect of large fuel loads on metabolic power input has never been empirically determined. We measured the total metabolic power input of a long-distance migrant, the red knot (Calidris canutus), flying for 6 to 10 h in a wind tunnel, using the doubly labelled water technique. Here we show that total metabolic power input increased with fuel load, but proportionally less than the predicted mechanical power output from the flight muscles. The most likely explanation is that the efficiency with which metabolic power input is converted into mechanical output by the flight muscles increases with fuel load. This will influence current models of bird flight and bird migration. It may also help to explain why some shorebirds, despite the high metabolic power input required to fly, routinely make nonstop flights of 4,000 km longer.

Avian pectoral muscle size rapidly tracks body mass changes during flight, fasting and fuelling

We used ultrasonic imaging to monitor short-term changes in the pectoral muscle size of captive red knots Calidris canutus. Pectoral muscle thickness changed rapidly and consistently in parallel with body mass changes caused by flight, fasting and fuelling. Four knots flew repeatedly for 10 h periods in a wind tunnel. Over this period, pectoral muscle thickness decreased in parallel with the decrease in body mass. The change in pectoral muscle thickness during flight was indistinguishable from that during periods of natural and experimental fasting and fuelling. The body-mass-related variation in pectoral muscle thickness between and within individuals was not related to the amount of flight, indicating that changes in avian muscle do not require power-training as in mammals. Our study suggests that it is possible for birds to consume and replace their flight muscles on a time scale short enough to allow these muscles to be used as part of the energy supply for migratory flight. The adaptive significance of the changes in pectoral muscle mass cannot be explained by reproductive needs since our knots were in the early winter phase of their annual cycle. Instead, pectoral muscle mass changes may reflect (i) the breakdown of protein during heavy exercise and its subsequent restoration, (ii) the regulation of flight capacity to maintain optimal flight performance when body mass varies, or (iii) the need for a particular protein:fat ratio in winter survival stores.

Maximum daily energy intake: it takes time to lift the metabolic ceiling

Conventionally, maximum capacities for energy assimilation are presented as daily averages. However, maximum daily energy intake is determined by the maximum metabolizable energy intake rate and the time available for assimilation of food energy. Thrush nightingales (Luscinia luscinia) in migratory disposition were given limited food rations for 3 d to reduce their energy stores. Subsequently, groups of birds were fed ad lib. during fixed time periods varying between 7 and 23 h per day. Metabolizable energy intake rate, averaged over the available feeding time, was 1.9 W and showed no difference between groups on the first day of refueling. Total daily metabolizable energy intake increased linearly with available feeding time, and for the 23-h group, it was well above suggested maximum levels for animals. We conclude that both intake rate and available feeding time must be taken into account when interpreting potential constraints acting on animals' energy budgets. In the 7-h group, energy intake rates increased from 1.9 W on the first day to 3.1 W on the seventh day. This supports the idea that small birds can adaptively increase their energy intake rates on a short timescale.

Wingbeat frequency and the body drag anomaly: wind-tunnel observations on a thrush nightingale (Luscinia luscinia) and a teal (Anas crecca)

A teal (Anas crecca) and a thrush nightingale (Luscinia luscinia) were trained to fly in the Lund wind tunnel for periods of up to 3 and 16 h respectively. Both birds flew in steady flapping flight, with such regularity that their wingbeat frequencies could be determined by viewing them through a shutter stroboscope. When flying at a constant air speed, the teal's wingbeat frequency varied with the 0.364 power of the body mass and the thrush nightingale's varied with the 0.430 power. Both exponents differed from zero, but neither differed from the predicted value (0.5) at the 1 % level of significance. The teal continued to flap steadily as the tunnel tilt angle was varied from -1 ° (climb) to +6 ° (descent), while the wingbeat frequency declined progressively by about 11 %. In both birds, the plot of wingbeat frequency against air speed in level flight was U-shaped, with small but statistically significant curvature. We identified the minima of these curves with the minimum power speed (Vmp) and found that the values predicted for Vmp, using previously published default values for the required variables, were only about two-thirds of the observed minimum-frequency speeds. The discrepancy could be resolved if the body drag coefficients (CDb) of both birds were near 0.08, rather than near 0.40 as previously assumed. The previously published high values for body drag coefficients were derived from wind-tunnel measurements on frozen bird bodies, from which the wings had been removed, and had long been regarded as anomalous, as values below 0.01 are given in the engineering literature for streamlined bodies. We suggest that birds of any size that have well-streamlined bodies can achieve minimum body drag coefficients of around 0.05 if the feet can be fully retracted under the flank feathers. In such birds, field observations of flight speeds may need to be reinterpreted in the light of higher estimates of Vmp. Estimates of the effective lift:drag ratio and range can also be revised upwards. Birds that have large feet or trailing legs may have higher body drag coefficients. The original estimates of around CDb=0.4 could be correct for species, such as pelicans and large herons, that also have prominent heads. We see no evidence for any progressive reduction of body drag coefficient in the Reynolds number range covered by our experiments, that is 21 600­215 000 on the basis of body cross-sectional diameter.