Development and characterization of immobilized cannabinoid receptor (CB1/CB2) open tubular column for on-line screening

Cannabinoid receptors, CB1 and CB2, are therapeutic targets in the treatment of anxiety, obesity, movement disorders, glaucoma, and pain. We have developed an on-line screening method for CB1 and CB2 ligands, where cellular membrane fragments of a chronic myelogenous leukemia cell line, KU-812, were immobilized onto the surface of an open tubular (OT) capillary to create a CB1/CB2-OT column. The binding activities of the immobilized CB1/CB2 receptors were established using frontal affinity chromatographic techniques. This is the first report that confirms the presence of functional CB1 and CB2 receptors on KU-812 cells. The data from this study confirm that the CB1/CB2-OT column can be used to determine the binding affinities (K(i) values) for a single compound and to screen individual compounds or a mixture of multiple compounds. The CB1/CB2-OT column was also used to screen a botanical matrix, Zanthoxylum clava-herculis, where preliminary results suggest the presence of a high-affinity phytocannabinoid.

Algorithmic network monitoring for a modern water utility: a case study in Jerusalem

We report on the design, deployment, and use of TaKaDu, a real-time algorithmic Water Infrastructure Monitoring solution, with a strong focus on water loss reduction and control. TaKaDu is provided as a commercial service to several customers worldwide. It has been in use at HaGihon, the Jerusalem utility, since mid 2009. Water utilities collect considerable real-time data from their networks, e.g. by means of a SCADA system and sensors measuring flow, pressure, and other data. We discuss how an algorithmic statistical solution analyses this wealth of raw data, flexibly using many types of input and picking out and reporting significant events and failures in the network. Of particular interest to most water utilities is the early detection capability for invisible leaks, also a means for preventing large visible bursts. The system also detects sensor and SCADA failures, various water quality issues, DMA boundary breaches, unrecorded or unintended network changes (like a valve or pump state change), and other events, including types unforeseen during system design. We discuss results from use at HaGihon, showing clear operational value.

Cross-reactive immunologic material status affects treatment outcomes in Pompe disease infants

Deficiency of acid alpha glucosidase (GAA) causes Pompe disease, which is usually fatal if onset occurs in infancy. Patients synthesize a non-functional form of GAA or are unable to form native enzyme. Enzyme replacement therapy with recombinant human GAA (rhGAA) prolongs survival in infantile Pompe patients but may be less effective in cross-reactive immunologic material (CRIM)-negative patients. We retrospectively analyzed the influence of CRIM status on outcome in 21 CRIM-positive and 11 CRIM-negative infantile Pompe patients receiving rhGAA. Patients were from the clinical setting and from clinical trials of rhGAA, were 6 months of age, were not invasively ventilated, and were treated with IV rhGAA at a cumulative or total dose of 20 or 40 mg/kg/2 weeks. Outcome measures included survival, invasive ventilator-free survival, cardiac status, gross motor development, development of antibodies to rhGAA, and levels of urinary Glc(4). Following 52 weeks of treatment, 6/11 (54.5%) CRIM-negative and 1/21 (4.8%) CRIM-positive patients were deceased or invasively ventilated (p<0.0001). By age 27.1 months, all CRIM-negative patients and 4/21 (19.0%) CRIM-positive patients were deceased or invasively ventilated. Cardiac function and gross motor development improved significantly more in the CRIM-positive group. IgG antibodies to rhGAA developed earlier and serotiters were higher and more sustained in the CRIM-negative group. CRIM-negative status predicted reduced overall survival and invasive ventilator-free survival and poorer clinical outcomes in infants with Pompe disease treated with rhGAA. The effect of CRIM status on outcome appears to be mediated by antibody responses to the exogenous protein.

The effect of alar cinch sutures and V-Y closure on soft tissue dynamics after Le Fort I intrusion osteotomies

Adverse effects on the soft tissues after Le Fort I osteotomies include: broadening of the alar base, loss of vermilion show of the upper lip and down sloping of the commissures. In theory, an alar cinch suture combined with a muco-musculo-periosteal V-Y closure (ACVY) should improve not only the nasal width, but would also improve the dynamics of some of the mimic muscles. To test the validity of this hypothesis, a prospective study was set up including 22 patients, using standardized full facial frontal photographs, taken immediately preoperatively and 18 months postoperatively. Sets containing three pictures were made: soft tissue in repose, maximum closed mouth smile and maximum smile. The landmarks, alare, crista philtri and cheilion were analysed. The preliminary results show that ACVY-closure does significantly improve the horizontal movement of cheilion with both maximum closed mouth smile and maximum smile, as well as the vertical movement of crista philtri with maximum closed mouth smile.

CONCLUSION

The Le Fort I osteotomy with ACVY improves the orofacial dynamics.

Use of intraoperative breast cancer sentinel lymph node (SLN) assay to predict of ≥4 positive (+) lymph nodes (LN)

530

Background: Predicting which patients will have ≥4 +LN and may need radiation therapy affects immediate breast reconstruction. We hypothesized that model s to predict the likelihood of ≥4+LN may be improved by incorporation of quantitative real time RT-PCR analysis of SLN. Methods: 728 patients were enrolled in 2 prospective studies of the GeneSearch BLN Assay (Veridex LLC) for SLN metastases. 205 (28.2%) were found to have +SLN by hematoxylin-eosin staining. Of these, 115 pts (15.8%) had tumors ≤5 cm in size with >4 total LN removed, forming the cohort of interest for this study. Quantitative cycle times (CT) for mammaglobin (MG) and CK19 were correlated with finding ≥4+LN on final pathology. Results: Median tumor size was 2.0 cm (range; 0.2–5.0 cm). Median number of SLN removed was 3 (range; 1–11). 18 patients (15.7%) had ≥4 +LN on final pathology. Median CT for MG was 29.1 (interquartile range (IQR): 24.7–39.0) in patients with <4 +LN vs. 21.4 (IQR: 18.5–26.8) in those with ≥4 +LN, p<0.001. Median CT for CK19 was 23.7 (IQR: 20.9–28.2) in patients with <4 +LN vs. 19.6 (IQR: 17.8–20.7) in those with ≥4 +LN, p<0.001. Tumor size ≥2cm, proportion of SLN+ >50%, MG CT <25.8 and CK19 <20.8 were correlated with ≥4 +LN on final pathology. On multivariate analysis, tumor size, MG CT and CK19 CT were significant (see table). A simplified CPR was created with 1 point given if tumor size was ≥2cm, 1 point if MG CT <25.8 and 2 points if CK19 CT<20.8. Of the 24 patients (20.9%) with 0 points, only 1 (4.2%) had ≥4 +LN; of the 12 patients (10.4%) with 3 points, 8 (66.7%) had ≥4 +LN on final pathology, p<0.001. Area under the receiver-operator curve was 86.2% (95% CI: 76.1%-96.2%). Conclusions: Intraoperative quantitative RT-PCR of SLN improves prediction of ≥4 +LN; further validation of this model will have clinical utility regarding the use of immediate, delayed, or delayed-immediate reconstruction approaches.

[Table: see text]

[Table: see text]

A phase II study of capecitabine (CAP) plus PHY906 in patients (pts) with advanced pancreatic cancer (APC)

e15508

Background: Gemcitabine (G) is regarded as the standard treatment for pts with APC. However, a standard second-line chemotherapy regimen has yet to be defined after G. PHY906, a 4-herb traditional Chinese medicine has a history of > 1,800 yrs of human use to treat GI symptoms including diarrhea. Preclinical studies showed that PHY906 may potentiate antitumor activity of CAP in human PANC-1 xenograft (ASCO 2007). A phase I study showed that CAP can be escalated up to 1750 mg/m2 PO BID on d1- 7 and PHY906 800mg PO BID on d1–4 q 2 wks with no DLTs (ASCO, 2008). Delivered dose-intensity of CAP was similar at 1750mg/m2 dose level as 1500mg/m2. Therefore, 1500mg/m2 of CAP and PHY906 was further tested in a phase II study as second-line treatment in pts with APC. Methods: Pts with G-refractory APC with ECOG PS <2 were treated with CAP 1500mg/m2 d1–7 with PHY906 800mg d1–4 q 2 wks. Response was assessed by CT scan according to RECIST q 6 wks and toxicity according to NCI-CTC v3.0. Primary objective is overall survival. Secondary objectives include overall RR, PFS and measurement of cytokines to assess inhibition of NF-kappa B, a possible mechanism responsible for PHY906's pharmacological activity. Results: As of January 5, 2009, 25 pts have been enrolled. Baseline characteristics include median age, 65 (range, 40–85); male/female,15/10; ECOG PS 0/1, 4/19; median cycles: 3 (r: 0.5–15). At this point 5 pts are still in active treatment. 4 pts have confirmed OS > 6 ms (1 still on study) with 2 further pts approaching 6 ms. Among evaluable pts, 1 had PR (5.3%), 11 SD (57.9%) and 7 PD (36.8%) after initial restaging scan. 36 % pts had >30% reduction in CA19–9 as biochemical response. There were 7 deaths on/within 30 days of study treatment, 6 related to PD and 1 had acute MI. G3/4 toxicities diarrhea 3/25 (12%), fatigue, 1/25 (4%), HFS 1/25 (4%) and mucositis 1/25 (4%). 1 pt was removed from study due to G3 HFS. Biomarker studies (IL4, GM-CSF, TNF-alpha, IL10, MCP-1, IL2, IL6) are ongoing. Conclusions: This is the first clinical study to evaluate a botanical formulation PHY906 with CAP in G-refractory APC pts. CAP + PHY906 regimen appears a safe and feasible salvage therapy in APC and warrants further investigation. In addition, PHY906 may have a cytoprotective antidiarrheal and anti-HFS effect, making treatment with CAP more tolerable.

[Table: see text]

Protein expression comparison and physiological profiling of matched pairs DCIS/normal and invasive/normal primary epithelial cells

Abstract #6031

Background: Approximately 50% of patients who are diagnosed with Ductal Carcinoma In-Situ (DCIS) develop invasive breast cancer. The progression from DCIS to invasive cancer is not well understood. To better understand the range of biological processes involved in this progression, we have successfully isolated primary epithelial cell cultures from patient breast tissue and are using mass spectrometry-based methods to identify differentially expressed proteins in these different cell types. Bioinformatics analysis was used to identify differences in the underlying pathways.&#x2028; Methods: Primary Human Mammary epithelial cells from DCIS and Stage 3 Invasive tumors and normal tissue from the same patient were isolated immediately after surgery. Cells were maintained in defined CNT27 media for up to 2 passages and were characterized for epithelial and breast cancer markers by immunohistochemistry and western blot. Tamoxifen response was measured by cell proliferation assay. Protein lysates were labeled with the ITRAQ isobaric tags. Two-dimensional high-pressure liquid chromatography and mass spectrometry were used to identify differentially expressed proteins.&#x2028; Results: The proliferation rate of cells from DCIS tissue was 33% higher than the matched control cells and 50% higher from invasive tissue. Furthermore, Tamoxifen was more effective at inhibiting DCIS cell proliferation than the invasive cells in a dose- and time-dependent manner. We identified 50-100 proteins differentially expressed between the different tissue types. Validated tumor markers such as members of protein S100 family were significantly different between the tumor and normal samples. Thrombospondin, a known angiogenesis inhibitor, had similar concentrations in normal and DCIS tissues but was down-regulated (ratio=0.4) in the invasive tumor samples.&#x2028; Discussion: Using the analogous methods from gene expression studies, we found that pathways associated with processes such as differentiation, angiogenesis, and invasion are enriched in the proteome of the invasive tumors. Further comparisons of additional samples is continuing with the goals of better understanding the underlying biology that drives DCIS to invasive breast cancer and ultimately defining markers that could be used in better prognosis for DCIS patients.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6031.

Pathogenesis and therapeutic approaches for improved topical treatment in localized scleroderma and systemic sclerosis

SSc is a chronic progressive disorder of unknown aetiology characterized by excess synthesis and deposition of collagen and other extracellular matrix components in a variety of tissues and organs. Localized scleroderma (LS) differs from SSc in that with LS only skin and occasionally subcutaneous tissues are involved. Although rarely life threatening, LS can be disfiguring and disabling and, consequently, can adversely affect quality of life. There is no known effective treatment for LS, and various options, including, as examples, corticosteroids and other immunomodulatory agents, ultraviolet radiation and vitamin D analogues, are of unproven efficacy. Clinical trials evaluating combination therapy such as corticosteroids with MTX or UVA1 exposure with psoralens have not been established as consistently effective. New immunomodulators such as tacrolimus and thalidomide are also being evaluated. A better understanding of the molecular and cellular mechanisms of LS has led to evaluation of new treatments that modulate profibrotic cytokines such as TGF-beta and IL-4, regulate assembly and deposition of extracellular matrix components, and restore Th1/Th2 immune balance by administering IL-12 or IFN-gamma. IFN-gamma acts by directly inhibiting collagen synthesis and by restoring immune balance. In this review, we evaluate current and future treatment options for LS and cutaneous involvement in SSc. Recent advances in therapy focus mainly on anti-fibrotic agents. Delivery of these drugs into the skin as the target tissue might be a key factor in developing more effective and safer therapy.

Characterization of a multiple ligand-gated ion channel cellular membrane affinity chromatography column and identification of endogenously expressed receptors in astrocytoma cell lines

Cellular membranes obtained from the 1321N1 and A172 astrocytoma cell lines were immobilized on a chromatographic phase to create cellular membrane affinity chromatography (CMAC) columns, CMAC(1321N1) and CMAC(A172). The columns were characterized using frontal affinity chromatography with [(3)H]-epibatidine as the marker ligand and epibatidine, nicotine, and methyllycaconitine as the displacers. The results indicated that the columns contained homomeric alpha7 nicotinic acetylcholine receptors (alpha7 nAChR) and heteromeric nicotinic acetylcholine receptors (alpha(x)beta(y) nAChRs), which was confirmed by the addition of subtype-specific inhibitors, alpha-bungarotoxin (alpha7 nAChR) and kappa-bungarotoxin (alpha(x)beta(y) nAChR) to the mobile phase. The presence of two additional ligand-gated ion channels (LGICs), gamma-aminobutyric acid (GABA(A)) and N-methyl-D-aspartic acid (NMDA), was established using frontal affinity chromatography with flunitrazepam and diazepam (GABA(A) receptor) and MK-801 and NMDA (NMDA receptor). The presence of the four LGICs was confirmed using confocal microscopy and flow cytometry. The results indicate that the CMAC(1321N1) and CMAC(A172) columns contain four independently functioning LGICs, that the columns can be used to characterize binding affinities of small molecules to each of the receptors, and that the CMAC approach can be used to probe the expression of endogenous membrane receptors.

Optical properties of a bio-inspired gradient refractive index polymer lens

The design, fabrication, and properties of one of a new class of gradient-index lenses are reported. The lens is an f/2.25 GRIN singlet based on a nanolayered polymer composite material, designed to correct for spherical aberration. The light gathering and focusing properties of the polymer lens are compared to a homogeneous BK7 glass singlet with a similar f-number. The modulation transfer function of the polymer GRIN lens exceeded that of the homogeneous glass lens at all spatial frequencies and was as much as 3 times better at 5 cyc/mm. The weight of the polymer lens was approximately an order of magnitude less than the homogeneous glass lens.

The FDA's assessment of follow-on protein products: a historical perspective

The scientific and regulatory issues that are associated with the possible introduction of 'follow-on' versions of protein drug products are the topic of considerable debate at present. Because of the differences between protein drug products and small-molecule drugs, the development of follow-on versions of protein products presents more complex scientific challenges than those presented by the development of generic versions of small-molecule drugs. Here, with a view to illustrating the Food and Drug Administration's (FDA's) scientific reasoning and experience in this area, we discuss past examples of the FDA's actions involving the evaluation of various types of follow-on and second-generation protein products and within-product manufacturing changes. The FDA believes its evaluation of the safety and effectiveness of follow-on protein products will evolve as scientific and technological advances in product characterization and manufacturing continue to reduce some of the complexity and uncertainty that are inherent in the manufacturing of protein products.

The reliability of frontal facial photographs to assess changes in nasolabial soft tissues

A simple, modified method to evaluate changes in the nasolabial soft tissues after orthognathic surgery is presented. Eighteen healthy volunteers were photographed in a standardized manner with a 2-month interval. Pictures were taken with the soft tissues in repose and 'maximum closed mouth smile'. Discrepancies for repose and dynamic excursions (x and y coordinates) were calculated for the landmarks alare, crista philtri and cheilion. Multiple analysis of variance revealed no significant interaction for intra-observer variance and time of recording. Coefficients of reliability (repose: 90-99%, dynamic excursion (cheilion): >95%), Spearman correlation coefficients (repose: >0.8, dynamic: >0.6) and squared correlation (repose: >75%, dynamic: >50%) showed this method to be reliable for repose and dynamic excursions. The error of measurement was less than 1.8 mm for both repose and dynamic excursions (SD(differences)=0.9 mm). This is smaller than mean differences in nasolabial soft-tissues excursions found between the pre- and post-Le Fort I osteotomy situation in a previous study using video imaging. The discrepancies found were in keeping with other earlier reports for 2D and 3D measuring methods. The method as proposed is simple, cost effective and can be used to evaluate soft-tissue changes after orthognathic surgery.

Self-exam is the most common method of breast cancer identification

1543

Background: Breast cancer survival is improved by early diagnosis. The role of self-exam as an adjunct to screening mammography has been questioned as some studies suggest that self-examinations lead to unnecessary diagnostic procedures without improving survival. Methods: Patients who had been diagnosed with breast cancer and who were attending a university-based cancer clinic were interviewed, using a structured questionnaire, to determine the way in which their breast cancers were first identified. Inference was conducted using exact methods (Clopper-Pearson intervals for proportions and Fisher’s test for odds ratios). Results: Breast cancers were first identified by mammogram in 16% of women, by provider in 9%, by the spouse in 2%. Seventy-five percent (95% CI=61% to 85%) of patients first identified their tumors by self exam. Self-identifiers occurred in all demographic groups. These women included those with all types of insurance: private insurance (68%), Medicare (60%), Medicaid (100%), or no insurance (85%); all levels of education: 77% with college education and 75% with high school; all income levels: for example, among 79% with annual incomes of <$10K and 73% with incomes >$50K; and among both black (91%) and white (66%) women. Of the women who reported both regular mammograms and regular self-examination (N=35), 77% (95% CI=60 to 90%) were self-identifiers. However, cancers found by mammography were more likely to be Stage I than were those identified by self-examination (odds ratio=3.9, 95% CI .9 to 17.5, p=.047). Conclusions: Most breast cancers (75%) were found by self-examination, even among women who had regular mammography. We did not find any demographic factor that predicted mammography as the primary method of tumor identification. These findings suggest that self-examination remains an important method of breast cancer identification.

No significant financial relationships to disclose.

Functional results after conservative treatment of fractures of the mandibular condyle

Since the introduction of osteosynthesis materials for rigid internal fixation after anatomical reduction there is an ongoing discussion about the treatment of condylar fractures of the mandible. Sixty patient files were analyzed and 28 patients were seen for re-examination and a x-orthopantomogram was taken. Functionality was graded with the Helkimo index at an average of 3.0 years follow-up. The clinical dysfunction index showed: severe symptoms in 11%, moderate symptoms in 39%, mild symptoms in 39% and 11% had no symptoms. Index for occlusal state showed: 21% severe occusal disturbances, 61% moderate occlusal disturbances and 18% no occlusal disturbances. According to the anamnestic dysfunction index 89% of the patients were symptom-free. The clinical outcome group showed a significant left/right ramus length difference compared with a 20-person control group. The re-examined group did not significantly differ from the control group. Conservative treatment for condylar fractures was successful in only 46% according to the 1999 consensus criteria described by Bos et al.

Factors predicting tumor size at presentation in breast cancer patients

10609

Background: Early diagnosis of breast cancer improves prognosis. A high percentage of women at our institution present with large breast cancers. Using tumor board records, we investigated the potential covariates associated with tumor size at presentation, including age, race, marital status, and insurance status in order to identify populations at risk for presenting with late stage disease. Methods: Data were obtained from tumor board records of University Health Systems, Greenville, NC, a regional referral center in rural Eastern North Carolina. We analyzed data from patients presenting between 1999 and 2005. Relationships between tumor size at diagnosis and explanatory variables (marital status, age, ethnicity, and insurance status) were explored. Results: 1568 patients with breast cancer were identified of which 32% were African American (AA), 67% were White (W), and 0.6% other. 8.3% of patients had Medicaid; 27%, Medicare; 53.5%, private insurance; 3.4%, HMO; and 6.1% were uninsured. Tumor size was 0.01 to 25 cm and highly skewed so that statistical inferences were conducted on the log of tumor size. Tumors of >5 cm were found in 13.8% of AA women as compared to 6.4% of W women. Overall tumor size in AA women was larger than in W women (p-value = .0000). Marital status was not statistically significant (p-value = .5148). A linear regression model for log tumor size at time of diagnosis using explanatory variables marital status, age, ethnicity, and insurance status showed that only race (p-value = .0000) and age (p-value = .0004) were statistically significant. Older patients presented with somewhat smaller tumors. Most of the variability in log tumor size remained unexplained (r-squared = 4%). Conclusions: AA women were more likely to present with large tumors. While Medicaid patients had larger tumors, insurance status was not statistically significant in the linear regression model due to partial confounding of insurance and race: 20.8% of AA women were on Medicaid compared to 2.6% of W women.

No significant financial relationships to disclose.

Mild traumatic brain injury induces persistent cognitive deficits and behavioral disturbances in mice

Victims of mild traumatic brain injury (mTBI) do not show clear morphological brain defects, but frequently suffer from long-lasting cognitive deficits, emotional difficulties and behavioral disturbances. In the present study, we investigated the effects of experimental mTBI in mice on cognition, spatial and non-spatial tasks, and depressive-like behavior in mice. Experimental brain injury was induced using a concussive head trauma, which creates the TBI by a weight-drop device. Different groups of mice were tested at 7, 30, 60, and 90 days post-injury for cognitive function (the swim T-maze and the passive avoidance test) and for depression-like behavior (the forced swimming test). These tests have been used infrequently in the past in mTBI research. Significant differences were observed between the injured mice compared to the controls in both the swim T-maze (day 30: p < 0.001) and passive avoidance (day 30: p < 0.05) tests. In addition, a significant difference was detected in the forced swimming test between the injured mice and the controls (day 7: p < 0.05; day 90: p < 0.01), which showed a depressive- like state in the injured animals beginning 7 days post-injury. These results demonstrate that persistent deficits in these tests of cognitive learning abilities and emergence of depressive-like behavior in injured mice are similar to those reported in human post-concussion syndrome.

Guided resonances in asymmetrical GaN photonic crystal slabs observed in the visible spectrum

We demonstrate that guided resonant modes can be readily observed in asymmetrical photonic crystal slabs on high-index substrates. In spite of the high radiative loss associated with all optical modes in these cases, the guided resonant modes are found to give rise to strong high-Q features in the transmission spectra. Since these photonic crystal structures are far more robust and easier to fabricate than the free-standing photonic crystal membranes used in previous studies of guided resonant modes, detailed studies of relevant optical phenomena and the implementation of proposed applications are greatly simplified.

Changing of hepatitis C virus genotype patterns in France at the beginning of the third millenium: The GEMHEP GenoCII Study

This cross-sectional study aimed to investigate, during a short period between 2000 and 2001, in a large population of patients with chronic hepatitis C, the epidemiological characteristics of hepatitis C virus (HCV) genotypes in France. Data from 26 referral centres, corresponding to 1769 patients with chronic hepatitis C were collected consecutively during a 6-month period. HCV genotyping in the 5'-non-coding region (NCR) was performed in each center using the line probe assay (LiPA, in 63% of cases), sequencing (25%) or primer-specific polymerase chain reaction (PCR) (12%). HCV genotypes 1a, 1b, 2, 3, 4, 5, non-subtyped 1 and mixed infection were found in 18, 27, 9, 21, 9, 3, 11 and 1% of our population, respectively. HCV genotype distribution was associated with gender, age, source and duration of infection, alanine aminotransferase (ALT) levels, cirrhosis, alcohol consumption, hepatitis B virus (HBV) and human immunodeficiency virus (HIV) coinfection. In multivariate analysis, only the source of infection was the independent factor significantly associated with genotype (P = 0.0001). In conclusion, this study shows a changing pattern of HCV genotypes in France, with i.v. drug abuse as the major risk factor, an increase of genotype 4, and to a lesser extent 1a and 5, and a decrease of genotypes 1b and 2. The modification of the HCV genotype pattern in France in the next 10 years may require new therapeutic strategies, and further survey studies.

The influence of orthognathic surgery on masticatory performance in retrognathic patients

Surgical correction of retrognathism may influence chewing performance and its underlying mechanisms selection and breakage of food particles. In this study we examined the hypothesis that treatment of this anomaly improves chewing performance. Furthermore, we determined to what extent this change can be attributed to selection and breakage of food particles. Eleven patients were tested before and 1-1.5 years after surgery. To determine chewing performance, eight cubes of 8 mm of a silicone rubber (Optosil) were used as a test food. Selection and breakage were determined in one-chew experiments using three particle sizes. On average, no differences were found for chewing performance, selection or breakage. However, on an individual basis, patients with a poor chewing performance before surgery tended to improve, whereas no improvement was observed for patients with a good chewing performance. The change in chewing performance was mainly due to a change in breakage of the food particles.