Sequential TPF chemotherapy followed by concurrent chemoradiotherapy in locally advanced head and neck cancer--a retrospective analysis of toxicity and outcomes

BACKGROUND AND AIMS

Phase III trials have shown that the addition of a taxane to cisplatin/5FU-based induction chemotherapy (TPF) improves response rates and overall survival in unresectable stage III/IV head and neck cancer. We sought to assess the tolerability, compliance and clinical outcomes of this treatment regime.

METHODS

A retrospective study of patients treated within a single centre between September 2007 and November 2010. Toxicities were graded according to CTCAE version 3.0. Survival, distant metastasis and local control rates are expressed as percentages at two years using the Kaplan-Meier method.

RESULTS

A total of 100 patients were identified (11% stage III, 86% stage IV) and 32% of patients were admitted as an emergency after TPF. The rate of neutropenic fever was 31%, this number fell to 9% when prophylactic G-CSF was used. In addition, 89% of patients underwent radical chemoradiation. Of these, 96% completed the full radiotherapy course. However, only 64% of patients received a minimum of two cycles of concurrent platinum chemotherapy. The two-year overall survival, metastasis free survival and local control rates were 62.6%, 88.5% and 73.3%, respectively.

CONCLUSIONS

TPF chemotherapy can be delivered safely in a non-trial cohort of patients. There is, however, a significant reduction in concurrent chemotherapy dose intensity. The long-term impact of this remains unclear.

Impaired macrophage phagocytosis in non-eosinophilic asthma

BACKGROUND

Many patients with non-eosinophilic asthma have increased numbers of neutrophils in the airways. The explanation for this chronic inflammation remains unclear, but may result from an impaired ability of alveolar macrophages to phagocytose apoptotic cells (a process termed 'efferocytosis'), as we have shown in chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To examine induced sputum as a non-invasive technique to characterize efferocytosis in chronic lung diseases and to compare efferocytosis in patients with non-eosinophilic asthma, eosinophilic asthma and COPD.

METHODS

Participants with stable asthma (20 with eosinophilic and 30 with non-eosinophilic) and COPD (n = 11) underwent clinical assessment including allergy skin tests, saline challenge and sputum induction. Sputum cells were dispersed using dithiothreitol and resuspended in culture medium. Efferocytosis of apoptotic bronchial epithelial cells by sputum-derived macrophages was determined using flow cytometry.

RESULTS

There were no significant differences in efferocytosis between paired sputum and bronchoalveolar lavage macrophages from three subjects. Efferocytosis was significantly impaired in patients with non-eosinophilic asthma [mean (SD) 0.95 (0.24)] compared with eosinophilic asthma [1.17 (0.19)] and to a similar degree as patients with COPD [1.04 (0.16)]. Sputum neutrophils were significantly higher in patients with COPD and non-eosinophilic asthma compared with eosinophilic asthma.

CONCLUSION AND CLINICAL RELEVANCE

Induced sputum provides a reliable and non-invasive method for studying macrophage efferocytosis in chronic lung disease. Macrophage efferocytosis is impaired in non-eosinophilic asthma to a similar degree as that in COPD and may explain the persistent airway neutrophilia and chronic inflammation that characterizes this asthma subtype.

A phenomenological model of muscle fatigue and the power-endurance relationship

The relationship between power output and the time that it can be sustained during exercise (i.e., endurance) at high intensities is curvilinear. Although fatigue is implicit in this relationship, there is little evidence pertaining to it. To address this, we developed a phenomenological model that predicts the temporal response of muscle power during submaximal and maximal exercise and which was based on the type, contractile properties (e.g., fatiguability), and recruitment of motor units (MUs) during exercise. The model was first used to predict power outputs during all-out exercise when fatigue is clearly manifest and for several distributions of MU type. The model was then used to predict times that different submaximal power outputs could be sustained for several MU distributions, from which several power-endurance curves were obtained. The model was simultaneously fitted to two sets of human data pertaining to all-out exercise (power-time profile) and submaximal exercise (power-endurance relationship), yielding a high goodness of fit (R(2) = 0.96-0.97). This suggested that this simple model provides an accurate description of human power output during submaximal and maximal exercise and that fatigue-related processes inherent in it account for the curvilinearity of the power-endurance relationship.

Longitudinally-graded optical fibers

Optical fibers have become ubiquitous tools for the creation, propagation, manipulation, and detection of light. However, while the intensity of light propagating through the fiber can increase or decrease along the length through amplification or attenuation, respectively, the properties of the fiber itself generally do not, thus removing an opportunity to further control the behavior of light and performance of fiber-based devices. Shown here are optical fibers that exhibit significant changes in their longitudinal optical properties, specifically a tailored longitudinal numerical aperture change of about 12% over less than 20 meters of length. This is about 1900 times greater than previously reported. The Brillouin gain coefficient was found to decrease by over 6 dB relative to a standard commercial single mode fiber. Next generation analogs are expected to exhibit more than a 10 dB reduction in SBS gain using larger, yet still reasonably manufacturable gradients over practical lengths.

Corticosteroid treatment selectively decreases mast cells in the smooth muscle and epithelium of asthmatic bronchi

BACKGROUND

Mast cells are important in the pathophysiology of airway inflammation and evidence suggests their sub-localisation within the airway is altered in asthma. Little is known about the effect of corticosteroids on mast cell localisation within the bronchi.

METHODS

We therefore performed an immunohistochemical analysis of mast cell numbers within the smooth muscle, epithelium and submucosa of healthy subjects (n = 10) and well-characterised asthmatic patients, using either β(2)-agonists alone (n = 10) or β(2)-agonists and inhaled corticosteroids (n = 10).

RESULTS

Patients using inhaled corticosteroids displayed significantly lower numbers of mast cells within their epithelium and smooth muscle compared to those not treated with inhaled corticosteroids. Submucosal mast cells were not affected by corticosteroid treatment. Numbers of smooth muscle mast cells correlated with bronchial responsiveness and epithelial mast cells with exhaled NO.

CONCLUSION

We demonstrate that glucocorticosteroids differentially affect mast cell numbers within specific airway sub-locations highlighting the importance of mast cell and smooth muscle/epithelial interactions in asthma pathogenesis.

Training in Current Medical Education: Surgeons are Different from Their Medical Colleagues

Education and training in surgery have focused on an apprenticeship style of learning, particularly in the operating theatre, with little emphasis on understanding how trainees learn. This focus on one style of training may not achieve the best possible outcomes. The need to deliver training over a shorter period since the introduction of the European WorkingTime regulations makes each learning opportunity vital. Learning styles have already been suggested as an important issue in obstetrics and gynaecology.

Do topical ophthalmic corticosteroids suppress the hypothalmic-pituitary-adrenal axis in post-penetrating keratoplasty patients?

PURPOSE

To establish whether hypothalmic-pituitary-adrenal axis suppression is possible secondary to long-term topical ophthalmic corticosteroid use in patients who have undergone penetrating keratoplasty (PKP).

METHODS

Patients who had undergone a PKP and had been using corticosteroid-based eye drops continuously for more than 6 months, with no history of concomitant steroid (oral, inhaled, or cutaneous) use, were included within the study. A low-dose short Synacthen (LDSST) test was performed in each patient followed later by a short Synacthen test (SST). The mean SST and LDSST after 30 min were calculated along with their corresponding 95% confidence intervals (CIs). Correlation between both baseline SST and baseline LDSST with duration of treatment was determined using Spearman's correlation.

RESULTS

In all, 20 patients were included within the study. The mean duration treatment was 28.2 months (range 11-96 months). All patients had normal baseline cortisol levels in both SST and LDSST tests. The mean 30 min SST was 753.8 nmol/l (95%CI: 696.6 nmol/l, 811.0 nmol/l) and no patients displayed inadequate adrenal response. The mean 30 min LDSST was 709.8 nmol/l (95%CI: 665.1 nmol/l, 754.5 nmol/l) and only one patient had an inadequate adrenal response. There was no correlation between baseline SST or LDSST and duration of treatment.

CONCLUSIONS

This study found no evidence that patients using continuous long-term corticosteroid eye drops after PKP experienced inadequate adrenal response. We did not find any evidence of a negative correlation between length of treatment and SST or LDSST measurements at baseline.

1.12 Tb/s superchannel coherent PM-QPSK InP transmitter photonic integrated circuit (PIC)

In this work, a 10-wavelength, polarization-multiplexed, monolithically integrated InP coherent QPSK transmitter PIC is demonstrated to operate at 112 Gb/sec per wavelength and total chip superchannel bandwidth of 1.12 Tb/s. This demonstration suggests that increasing data capacity to multi-Tb/s per chip is possible and likely in the future.

Prospective study of antenatally diagnosed congenital cystic adenomatoid malformations

PURPOSE

Congenital cystic adenomatoid malformations (CCAMs) are increasingly diagnosed in recent years due to the routine usage of antenatal ultrasound. The aim of this study was to present the natural course and outcome of antenatally diagnosed cystic lung diseases, which were prospectively studied.

METHODS

Between the period June 2004 and June 2010, 25 fetuses with suspected CCAMs were seen in a single tertiary maternal fetal unit. One child was excluded as the fetal MRI suggested congenital diaphragmatic hernia. Data were prospectively entered into a database including antenatal and postnatal findings which were then analyzed.

RESULTS

Mean gestational age at the time of diagnosis was 20.8 weeks (range 17-29). Fetal interventions included amnioreduction (n = 2) and fetal thoracocentesis (n = 3) in one child. The mean gestational age at delivery was 38.5 weeks (range 31.6-40.6). None of the mothers underwent termination of pregnancy or spontaneous abortion. All patients underwent postnatal radiological assessment. Of the 24 cases, 5 children were symptomatic in the immediate neonatal period and 19 were asymptomatic. Anatomical surgical resection was undertaken in all symptomatic cases. There was one death in this group due to severe pre-existing pulmonary hypoplasia. Among the 19 asymptomatic cases, 5 children were managed conservatively as the lesions were not significant and the remaining 14 (73%) underwent surgical resection. The mean age at surgery was 11.1 months (range 3.3-34 months). Postnatal pathology confirmed CCAM in all operated cases, except one who had pulmonary sequestration.

CONCLUSION

Antenatally diagnosed CCAMs have an excellent prognosis except in children with a large lesion and associated with lung hypoplasia. Postnatal investigations are required in all cases to confirm the diagnosis. Symptomatic CCAMs require immediate surgery in the neonatal period with a good outcome. Asymptomatic CCAMs can be safely operated between 9 and 12 months of age.

The oral health needs of children, adolescents and young adults affected by a mucopolysaccharide disorder

BACKGROUND

As one of the 4 United Kingdom national centres for Lysosomal Storage Disorders, Birmingham Children's Hospital (BCH) cares for 49 patients with a mucopolysaccharide (MPS) disorder. Presently, their oral health needs have never been fully investigated. Enzyme therapies are revolutionising medical treatment, and will prolong life expectancy. Therefore, oral health and its impact on quality of life are increasingly important.

HYPOTHESIS

Patients with an MPS disorder have greater oral health needs in comparison with the general population.

DESIGN

Forty-six patients with an MPS disorder were investigated for caries, gingival health and enamel opacities. Questionnaires to establish the utilisation of dental services and assess the perceived difficulties in achieving adequate oral health care were completed.

RESULTS

Patients with an MPS disorder have specific oral health needs depending on the type of MPS experienced. This study found 76% of patients with MPS IV had experienced dental caries and they all showed evidence of a generalised unspecified enamel defect. Subjects with MPS I, II and III did not have an increased caries rate; 50% of the study group had received dental treatment in the past, of which 74% (17, n = 23) required a general anaesthetic.

CONCLUSION

The MPS disorders can have a significant effect on the developing dentition. Subjects with MPS IV do have an increased oral health need in comparison with the general population and the other MPS groups due to their increased caries rate and enamel defects. Further research is required to fully assess their needs and investigate any structural tooth defects.

Severe late anemia of hemolytic disease of the newborn

Late anemia is a well-recognized complication of Rhesus hemolytic disease of the newborn (HDN). The incidence of Rhesus HDN is declining, with a tendency for more severely affected pregnancies to be managed in specialist centres. Consequently, many paediatric departments may see relatively few affected infants with comparatively mild disease, and the risk of late anemia in such cases may not always be appreciated. Two cases of infants born with evidence of Rhesus isoimmunization noted at birth and encountering no immediate problems other than mild hyperbilirubinemia are described. After an uneventful early neonatal course, both infants were discharged without follow-up and presented in the second to third weeks of life with severe, life-threatening anemia, leading to neurological sequelae in one case. The importance of close surveillance, including hemoglobin measurements, in all infants with Rhesus hemolytic disease, irrespective of initial severity, is reiterated.

Patterns of airway disease and the clinical diagnosis of asthma in the Busselton population

The aim of this study was to examine how objective measures related to lung function cluster in the general population and how the patterns relate to asthma and bronchitis as diagnosed by a doctor (DDA and DDB, respectively). A cross-sectional survey of an age-stratified random general population sample of 1,969 adults from the electoral register of Busselton (Australia) was performed in 2005-2007. Respiratory symptoms, DDA ever, DDB ever, recent wheezing and smoking history, together with anthropometric measurements, forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC), methacholine challenge or bronchodilator response, exhaled nitric oxide (eNO), skin-prick tests to common allergens, and blood eosinophil and neutrophil counts were studied. Cluster analysis (variables sex, age, atopy, FEV₁ % predicted, FEV₁/FVC, airway hyperresponsiveness, eNO, log eosinphil count, log neutrophil count and body mass index) was used to identify phenotypic patterns. Seven clusters (subjects with DDA and DDB, respectively) were identified: normal males (n=467; 7 and 13%), normal females (n=477; 12 and 18%), obese females (n=250; 16 and 28%), atopic younger adults (n=330; 21 and 17%), atopic adults with high eNO (n=130; 30 and 25%), atopic males with reduced FEV₁ (n=103; 33 and 32%) and atopic adults with bronchial hyperreactivity (n=212; 40 and 26%). The clinical diagnosis of asthma (ever) and bronchitis (ever) is not specific for any of the clustering patterns of airway abnormality.

Greater white and grey matter changes associated with early cannabis use in adolescent-onset schizophrenia (AOS)

BACKGROUND

Cannabis use is associated with a higher risk of schizophrenia, however, its specific long-term effect on the structure of the brain of adolescent-onset schizophrenic patients remains unclear.

AIMS

To study cognitive and structural (grey and white matter) changes in patients with adolescent-onset schizophrenia (AOS) with early cannabis use (CAN+ve) (more than 3 times/week for at least 6 months) and without cannabis use (CAN-ve) versus controls.

METHOD

An optimised voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) MRI study of 32 adolescents with DSM IV schizophrenia-16 CAN+ve and 16 CAN-ve, and 28 healthy adolescents.

RESULTS

Compared to CAN-ve subjects, CAN+ve subjects showed GM density loss in temporal fusiform gyrus, parahippocampal gyrus, ventral striatum, right middle temporal gyrus, insular cortex, precuneus, right paracingulate gyrus, dorsolateral prefrontal cortex, left postcentral gyrus, lateral occipital cortex and cerebellum. Similar group comparison showed decreased fractional anisotropy (FA) in particular in brain stem, internal capsule, corona radiata, superior and inferior longitudinal fasciculus in CAN+ve patients. No cognitive differences were apparent between CAN+ve and CAN-ve subjects, and both were impaired relative to controls.

CONCLUSION

Cannabis use in early adolescence increases WM and GM deficits in AOS, but does not appear to increase the cognitive deficit associated with this illness.

Chromosomal alterations in Malaysian patients with nasopharyngeal carcinoma analyzed by comparative genomic hybridization

Nasopharyngeal carcinoma (NPC) is one of the most common cancers in Malaysia, mainly occurring among the Chinese population. To detect common genetic alterations in NPC, we screened seven cases of NPC using the comparative genomic hybridization (CGH) technique. Before proceeding to the CGH technique, the tumors were first confirmed to consist of 75% tumor cells or more. In brief, the technique consists of binding tumor DNA with normal DNA and human Cot-1 DNA, which is then hybridized to normal metaphase spreads. The slides were then counterstained with 4,6 diamino-2-phenylindole (DAPI II) for detection. Analyses were performed using CGH software (Cytovision). We found genetic alterations in all seven NPC samples. The common chromosomal gains (57%, four cases) were found on chromosome arms 1q, 4p, 5, 7q, 11, 14p, 15q, 18p, and 21p, and common chromosomal losses (43%, three cases) were found on chromosome arm 16p. Our results showed chromosomal alterations in all seven NPC cases in the Malaysian population. This result provides the platform for further investigations to locate tumor suppressor genes and oncogenes at specific chromosomal regions in Malaysian NPC patients.

Revisiting imaging features and the embryologic basis of third and fourth branchial anomalies

BACKGROUND AND PURPOSE

There is wide discrepancy between common clinical and radiologic presentations of branchial sinuses arising from the pyriform fossa and the theoretic course of third and fourth branchial arch anomalies. The purpose of this study was to revisit the clinical presentations and imaging features of such anomalies in children.

MATERIALS AND METHODS

A retrospective review of institutional and diagnostic imaging data bases from 1998 to 2008 for reported cases of third and fourth branchial cleft anomalies was conducted. Clinical presentation, pharyngoscopy results, and imaging features in all the patients were evaluated. Surgical and histopathology correlation in patients who underwent excision of the tract was also obtained.

RESULTS

Twenty reported cases described as third or fourth branchial apparatus anomalies were identified. There were 12 females and 8 males with a mean age of 84.6 months. The most common presentation was an inflammatory neck mass (18/20, 90%) almost always involving the thyroid gland. Most lesions were on the left side (16/20, 80%). Pharyngoscopy showed a sinus opening at the piriform fossa in 18/20 (90%) cases. None of the cases followed the classic theoretic pathway of third and fourth arch remnants. Histopathology showed tracts lined with pseudostratified squamous epithelium or ciliated columnar epithelium often associated with inflammatory changes in 17 surgically resected cases.

CONCLUSIONS

Branchial sinuses arising from the pyriform fossa often present with an inflammatory neck mass involving the thyroid lobe, most often on the left side. Imaging and surgical findings suggest that they arise from the embryonal thymopharyngeal duct of the third branchial pouch, because they do not follow the hypothetic course of third or fourth arch fistulas.

Increased myoepithelial cells of bronchial submucosal glands in fatal asthma

BACKGROUND

Fatal asthma is characterised by enlargement of bronchial mucous glands and tenacious plugs of mucus in the airway lumen. Myoepithelial cells, located within the mucous glands, contain contractile proteins which provide structural support to mucous cells and actively facilitate glandular secretion.

OBJECTIVES

To determine if myoepithelial cells are increased in the bronchial submucosal glands of patients with fatal asthma.

METHODS

Autopsied lungs from 12 patients with fatal asthma (FA), 12 patients with asthma dying of non-respiratory causes (NFA) and 12 non-asthma control cases (NAC) were obtained through the Prairie Provinces Asthma Study. Transverse sections of segmental bronchi from three lobes were stained for mucus and smooth muscle actin and the area fractions of mucous plugs, mucous glands and myoepithelial cells determined by point counting. The fine structure of the myoepithelial cells was examined by electron microscopy.

RESULTS

FA was characterised by significant increases in mucous gland (p = 0.003), mucous plug (p = 0.004) and myoepithelial cell areas (p = 0.017) compared with NAC. When the ratio of myoepithelial cell area to total gland area was examined, there was a disproportionate and significant increase in FA compared with NAC (p = 0.014). Electron microscopy of FA cases revealed hypertrophy of the myoepithelial cells with increased intracellular myofilaments. The NFA group showed changes in these features that were intermediate between the FA and NAC groups but the differences were not significant.

CONCLUSIONS

Bronchial mucous glands and mucous gland myoepithelial cell smooth muscle actin are increased in fatal asthma and may contribute to asphyxia due to mucous plugging.

Identifying women requiring maternity high dependency care

The prompt identification of clinical deterioration and referral for appropriate care are key issues in the management of women who become critically ill during pregnancy, labour and the postpartum period. The Intensive Care Society has developed designated levels of care in relation to adult patient care, which may not be appropriate for use in midwifery. Therefore, exploring the midwifery, nursing and medical literature related to levels of care and detection of clinical deterioration may highlight the need for these to be modified and adapted for the development of midwifery-specific levels of care that are appropriate for this cohort.

The current status of materials for posterior composite restorations: the advent of low shrink

Polymerization contraction, and the stresses associated with this, have presented problems with resin composite materials, particularly when used to restore cavities in posterior teeth. This paper summarizes the problems associated with polymerization contraction and examines methods used to overcome this, in particular, by the use of materials which have reduced percentage contraction when compared with traditional materials.

CLINICAL RELEVANCE

Use of a material with reduced polymerization contraction should lead to simpler restoration placement.

Developing and piloting an audit tool for mental health education and training: The National Mental Health Education Continuous Quality Improvement Tool

It is clear from the international literature that education and training can play a crucial role in improving the quality of mental health service delivery. In the UK, post-qualification mental health education and training is not generally allied to the national policy agenda and there is a lack of service user and carer involvement in the design, development and delivery of educational curricula. The Department of Health in England has funded the development of a continuous quality improvement tool to address these important concerns and help commissioners of mental health education and training evaluate key aspects of courses. The design of the tool was informed by the literature and a series of semi-structured interviews and focus groups with key stakeholders. Subsequent drafts were refined through steering group consultation and the instrument was then piloted within a selected region in England. This has resulted in a brief, user-friendly tool that takes into account the views of all stakeholders in mental health education programmes, promotes dialogue and facilitates continuous quality improvement. The tool promotes self-assessment of: partnership arrangements; the relevance of the programme to the policy context; the extent to which service users and carers are involved in the design, delivery and evaluation of programmes; and the assessment of the impact of the programme. Results from the initial implementation project (to be reported separately) suggest that the tool is welcomed and can complement existing quality mechanisms.

Comparison between phytoestrogens and estradiol in the preventionof atheroma in ovariectomized cholesterol-fed rabbits

OBJECTIVES

There is increasing interest in the role of complementary and alternative medicines for the treatment of menopause-related problems. This study compared the preventive effect on atheroma formation of a commercially available mixed phytoestrogen concentrate with that of estradiol.

METHODS

An ovariectomized cholesterol-fed rabbit model of atheroma formation was used. Rabbits were ovariectomized before the commencement of the 12-week treatment period. There were two control groups. Control Group 1 received isoflavone-free rabbit chow whilst Control Group 2 received 1% cholesterol-enriched isoflavone-free rabbit chow. Rabbits in Group 3 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 500 mg tablet containing a concentrated extract of Trifolium pretense (red clover). Rabbits in Group 4 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 0.5 mg tablet of oral estradiol. Atheroma formation was measured by, first, calculation of the area of atheroma on the intimal surface, and, second, measuring the cholesterol content in the aorta.

RESULTS

There were no significant differences in serum cholesterol between the cholesterol-fed control Group 2 and the treatment Groups 3 and 4. However, there was significantly less staining for atheroma and significantly less cholesterol accumulation in the aorta in Group 4 (estradiol-treated) rabbits compared with either control Group 2 or Group 3 (phytoestrogen-treated) rabbits.

CONCLUSION

In this study, only estradiol was shown to have a significant protective effect against atheroma formation.

Optimizing the encounter rate in biological interactions: Ballistic versus Lévy versus Brownian strategies

Bartumeus et al. [Phys. Rev. Lett. 88, 097901 (2002)] compared the efficiency of a Lévy random walk predator strategy with a Brownian random walk strategy in a periodic one-dimensional domain with nonrevisitable moving targets. Their findings from numerical simulations conclude that "a Lévy search strategy is the best option in some, but not all, cases for a random search process." Using the same methodology, we show that the simplest random search strategy of all, ballistic motion in a random direction, outperforms a Lévy strategy in almost every case. We further show that, in the small set of cases where the ballistic strategy is not optimal, the periodic model does not capture the more realistic nonperiodic case. In the nonperiodic case, the ballistic strategy again outperforms the Lévy strategy.

Optimal foraging: Lévy pattern or process?

Many different species have been suggested to forage according to a Lévy walk in which the distribution of step lengths is heavy-tailed. Theoretical research has shown that a Lévy exponent of approximately 2 can provide a higher foraging efficiency than other exponents. In this paper, a composite search model is presented for non-destructive foraging behaviour based on Brownian (i.e. non-heavy-tailed) motion. The model consists of an intensive search phase, followed by an extensive phase, if no food is found in the intensive phase. Quantities commonly observed in the field, such as the distance travelled before finding food and the net displacement in a fixed time interval, are examined and compared with the results of a Lévy walk model. It is shown that it may be very difficult, in practice, to distinguish between the Brownian and the Lévy models on the basis of observed data. A mathematical expression for the optimal time to switch from intensive to extensive search mode is derived, and it is shown that the composite search model provides higher foraging efficiency than the Lévy model.