Relationship Between Colonic Transit Response to Eating With Self-reported Constipation Severity in Constipated Patients According to the Phenotype.

Background/Aims: Eating is the major synchronizer of gastrointestinal motility and secretions. The present study aims to evaluate the interplay between self-perceived constipation severity (CS) and colonic response to eating in constipated patients according to the phenotype. Methods: We included 387 consecutive outpatients complaining of Rome IV chronic idiopathic constipation. Likert scales for CS, abdominal pain severity, bloating severity, depression and anxiety assessment, total and segmental colonic transit time (CTT), and colonic transit response to eating (CTRE) were performed in all patients. Results: Of the 387 patients included (49.7 ± 16.4 years), 320 (83%) were female, 203 had irritable bowel syndrome with constipation (IBS-C), 184 as functional constipation (FC), and 283 had defecation disorders (DD). The female gender was characterized by increased bloating severity (P = 0.011) and decreased Bristol stool form (P = 0.002). In IBS-C and FC patients, CS was related with bloating severity (P < 0.001 in both groups) and total CTT (P = 0.007 in IBS-constipation, P = 0.040 in FC). In IBS-C patients, CS was also associated with abdominal pain severity (P = 0.003) and Bristol stool form (P = 0.004). In contrast, in FC, CS was only related to left CTRE (P = 0.006), and in patients with DD, CS was associated with total CTT (P < 0.001) and left CTRE (P = 0.002). Conclusion: Colonic transit response to eating was not associated to CS in IBS-C patients, but left CTRE was associated with constipation severity in FC and DD patients.

Dose summation and image registration strategies for radiobiologically and anatomically corrected dose accumulation in pelvic re-irradiation.

BACKGROUND: Re-irradiation (reRT) is a promising technique for patients with localized recurrence in a previously irradiated area but presents major challenges. These include how to deal with anatomical change between two courses of radiotherapy and integration of radiobiology when summating original and re-irradiation doses. The Support Tool for Re-Irradiation Decisions guided by Radiobiology (STRIDeR) project aims to develop a software tool for use in a commercial treatment planning system to facilitate more informed reRT by accounting for anatomical changes and incorporating radiobiology. We evaluated three approaches to dose summation, incorporating anatomical change and radiobiology to differing extents. METHODS: In a cohort of 21 patients who previously received pelvic re-irradiation the following dose summation strategies were compared: (1) Rigid registration (RIR) and physical dose summation, to reflect the current clinical approach, (2) RIR and radiobiological dose summation in equivalent dose in 2 Gy fractions (EQD2), and (3) Patient-specific deformable image registration (DIR) with EQD2 dose summation. RESULTS: RIR and physical dose summation (Strategy 1) resulted in high cumulative organ at risk (OAR) doses being 'missed' in 14% of cases, which were highlighted by EQD2 dose summation (Strategy 2). DIR (with EQD2 dose summation; Strategy 3) resulted in improved OAR overlap and distance to agreement metrics compared to RIR (with EQD2 dose summation; Strategy 2) and was consistently preferred in terms of clinical utility. DIR was considered to have a clinically important impact on dose summation in 38% of cases. CONCLUSION: Re-irradiation cases require individualized assessment when considering dose summation with the previous treatment plan. Fractionation correction is necessary to meaningfully assess cumulative doses and reduce the risk of unintentional OAR overdose. DIR can add clinically relevant information in selected cases, especially for significant anatomical change. Robust solutions for cumulative dose assessment offer the potential for future improved understanding of cumulative OAR tolerances.

Abdominal Pain Severity Is Mainly Associated with Bloating Severity in Patients with Functional Bowel Disorders and Functional Abdominal Pain.

PURPOSE: Abdominal pain is a cardinal sign of functional bowel disorders (FBD), in favor of irritable bowel syndrome (IBS). However, the determinants of abdominal pain severity (APS) are unknown. The present study aimed to search the relationships between APS and demographic, psychological, and clinical parameters in tertiary care FBD outpatients. PATIENTS AND METHODS: In this retrospective study, we included 2043 new outpatients with FBD or functional abdominal pain. They fulfilled the Rome III questionnaire, psychological evaluation, and four 10-points Likert scale for the perceived severity of constipation, diarrhea, bloating, and abdominal pain. Linear regression was performed for each phenotype to model the severity of abdominal pain with demographic, psychological parameters, and symptoms severity. RESULTS: APS was positively associated with bloating severity in all phenotypes, but APS was also associated with other variables according to gender and phenotype. APS was negatively associated with age and positively with depression, constipation severity, and diarrhea severity in female patients. In male patients, APS was associated with state anxiety, constipation severity, and diarrhea severity. APS severity was associated with bloating severity and transit severity in IBS patients, while in non-IBS patients, APS was only associated with bloating severity. CONCLUSION: Perceived abdominal pain severity is always associated with perceived bloating severity in FBD and FAP patients.

Biliary pancreatitis in a duplicate gallbladder: a case report and review of literature.

Duplicated gallbladder is a rare congenital anomaly that require special attentions due to its clinical, surgical and diagnostic difficulties. We present a case of a 39-year-old female patient with a duplicated gallbladder who presented with an acute biliary pancreatitis, a case to our knowledge is the first in the literature. A double gallbladder in an abdominal ultrasonography was doubtful, thus a computed tomography scan, a magnetic resonance cholangiopancreatography and an endoscopic retrograde cholangiopancreatography were done that confirmed the double gallbladder. A laparoscopic cholecystectomy with an intraoperative cholangiography was performed safely two months after the acute attack. The histopathological report revealed a Y-shaped type 1 double gallbladder according to the Harlaftis et al. classification.

Loss of local control due to tumor displacement as a function of margin size, dose-response slope, and number of fractions.

PURPOSE: Geometric uncertainties are inevitable in radiotherapy. To account for these uncertainties, a margin is added to the clinical target volume (CTV) to create the planning target volume (PTV), and its size is critical for obtaining an optimal treatment plan. Dose-based (i.e., physical) margin recipes have been published and widely used, but it is important to consider fractionation and the radiobiological characteristics of the tumor when deriving margins. Hence a tumor control probability (TCP)-based margin is arguably more appropriate. METHODS: Margins required for ≤ 1% loss in mean population TCP (relative to a static tumor) for varying numbers of fractions, varying slope of the dose-response curve (γ50) and varying degrees of dose distribution conformity are investigated for spherical and four-field (4F)-brick dose distributions. To simulate geometric uncertainties, systematic (Σ) and random (σ) tumor displacements were sampled from Gaussian distributions and applied to each fraction for a spherical CTV. Interfraction tumor motion was simulated and the dose accumulated from fraction to fraction on a voxel-by-voxel basis to calculate TCP. PTV margins derived from this work for various fraction numbers and dose-response slopes (γ50) for different degrees of geometric uncertainties are compared with margins calculated using published physical-dose- and TCP-based recipes. RESULTS: Larger margins are required for a decrease in the number of fractions and for an increase in γ50 for both spherical and 4F-brick dose distributions. However, the margins can be close to zero for the 4F-brick distribution for small geometric uncertainties (Σ = 1, σ = 1 mm) irrespective of the number of fractions and the magnitude of γ50 due to the higher "incidental" dose outside the tumor. For Σ = 1 mm and σ = 3 mm, physical-dose-based recipes underestimate the margin only for the combination of hypofractionated treatments and tumors with a high γ50. For all other situations TCP-based margins are smaller than physical-dose-based recipes. CONCLUSIONS: Margins depend on the number of fractions and γ50 in addition to Σ and σ. Dose conformity should also be considered since the required margin increases with increasing dose conformity. Ideally margins should be anisotropic and individualized, taking into account γ50, number of fractions, and the dose distribution, as well as estimates of Σ and σ. No single "recipe" can adequately account for all these variables.

(Radio)biological optimization of external-beam radiotherapy.

"Biological optimization" (BIOP) means planning treatments using (radio)biological criteria and models, that is, tumour control probability and normal-tissue complication probability. Four different levels of BIOP are identified: Level I is "isotoxic" individualization of prescription dose D(presc) at fixed fraction number. D(presc) is varied to keep the NTCP of the organ at risk constant. Significant improvements in local control are expected for non-small-cell lung tumours. Level II involves the determination of an individualized isotoxic combination of D(presc) and fractionation scheme. This approach is appropriate for "parallel" OARs (lung, parotids). Examples are given using our BioSuite software. Hypofractionated SABR for early-stage NSCLC is effectively Level-II BIOP. Level-III BIOP uses radiobiological functions as part of the inverse planning of IMRT, for example, maximizing TCP whilst not exceeding a given NTCP. This results in non-uniform target doses. The NTCP model parameters (reflecting tissue "architecture") drive the optimizer to emphasize different regions of the DVH, for example, penalising high doses for quasi-serial OARs such as rectum. Level-IV BIOP adds functional imaging information, for example, hypoxia or clonogen location, to Level III; examples are given of our prostate "dose painting" protocol, BioProp. The limitations of and uncertainties inherent in the radiobiological models are emphasized.

An analytical approach to acceptance criteria for quality assurance of Intensity Modulated Radiotherapy.

Detectability and impact of potential treatment machine errors on IMRT treatments were evaluated. The ability of the gamma index to detect deliberately introduced errors was assessed and their clinical impact was assessed using Tumour Control Probability (TCP) and Normal Tissue Complication Probability. TCP was only marginally affected by 2mm errors in MLC position. Dose delivery errors had greater impact but were not detected as effectively using the gamma index. Acceptance criteria should include mean dose as well as gamma to help identify errors in the delivered dose.

Exploiting a list of protein sequences.

We describe a software program to help exploit a database of aligned protein sequences. In addition to the classical lists of sequences, a graphical representation is used to get a better overview of the information. As natural parameters, the type of amino acid and sequence position are used. Various plots or 3D representations are then updated. Examples are shown based on globin sequences from various species and on the abnormal human hemoglobins. The software should be of interest to protein engineers who need to know what variants are already known.

High pressure enhances hexacoordination in neuroglobin and other globins.

The techniques of high applied pressure and flash photolysis have been combined to study ligand rebinding to neuroglobin (Ngb) and tomato Hb, globins that may display a His-Fe-His hexacoordination in the absence of external ligands. High pressure induces a moderate decrease in the His association rate and a large decrease in His dissociation rate, thus leading to an enhancement of the overall His affinity. The overall structural difference between penta- and hexacoordinated globins may be rather small and can be overcome by external modifications such as high pressure. Over the pressure range 0.1-700 MPa (7 kbar), the globins may show a loss of over a factor of 100 in the amplitude of the bimolecular rebinding phase after photodissociation. The kinetic data show that pressure induces a moderate increase of the rate for ligand binding from the correlated pair state (just after photodissociation) and a large (factor of 1000) decrease in rate for migration through the protein. The effect on the ligand migration phase was similar for both the external ligands (such as oxygen) as for the internal (histidine) ligand, suggesting the dominant role of protein fluctuations, rather than specific chemical barriers. Thus high pressure efficiently closes the protein migration channels; however, contrary to the effect of high viscosity, high pressure induces a greater decrease in rate for ligand migration toward the exterior (heme to the solvent) versus inward migration, as if the presence of the ligand itself induces an additional steric constraint.

Hyperthermal stability of neuroglobin and cytoglobin.

Neuroglobin (Ngb) and cytoglobin (Cygb), recent additions to the globin family, display a hexa-coordinated (bis-histidyl) heme in the absence of external ligands. Although these proteins have the classical globin fold they reveal a very high thermal stability with a melting temperature (Tm) of 100 degrees C for Ngb and 95 degrees C for Cygb. Moreover, flash photolysis experiments at high temperatures reveal that Ngb remains functional at 90 degrees C. Human Ngb may have a disulfide bond in the CD loop region; reduction of the disulfide bond increases the affinity of the iron atom for the distal (E7) histidine, and leads to a 3 degrees C increase in the T(m) for ferrous Ngb. A similar Tm is found for a mutant of human Ngb without cysteines. Apparently, the disulfide bond is not involved directly in protein stability, but may influence the stability indirectly because it modifies the affinity of the distal histidine. Mutation of the distal histidine leads to lower thermal stability, similar to that for other globins. Only globins with a high affinity of the distal histidine show the very high thermal stability, indicating that stable hexa-coordination is necessary for the enhanced thermal stability; the CD loop which contains the cysteines appears as a critical region in the neuroglobin thermal stability, because it may influence the affinity of the distal histidine.

Neuroglobin and other hexacoordinated hemoglobins show a weak temperature dependence of oxygen binding.

Mouse and human neuroglobins, as well as the hemoglobins from Drosophila melanogaster and Arabidopsis thaliana, were recombinantly expressed in Escherichia coli, and their ligand-binding properties were studied versus temperature. These globins have a common feature of being hexacoordinated (via the distal histidine) under deoxy conditions, as evidenced by a large amplitude for the alpha absorption band at 560 nm and the Soret band at 426 nm. The transition from the hexacoordinated form to the CO bound species is slow, as expected for a replacement reaction Fe-His --> Fe --> FeCO. The intrinsic binding rates would indicate a high oxygen affinity for the pentacoordinated form, due to rapid association and slow (100 ms-1 s) dissociation. However, the competing protein ligand results in a much lower affinity, on the order of magnitude of 1 torr. In addition to decreasing the affinity for external ligand, the competitive internal ligand leads to a weaker observed temperature dependence of the ligand affinity, since the difference in equilibrium energy for the two ligands is much lower than that of ligand binding to pentacoordinated hemoglobin. This effect could be of biological relevance for certain organisms, since it could provide a globin with an oxygen affinity that is nearly independent of temperature.

Coupling of the heme and an internal disulfide bond in human neuroglobin.

Neuroglobin displays a hexacoordination His-Fe-His in the absence of external ligands such as oxygen. The observed oxygen affinity therefore depends on the binding rates of both oxygen and the competing distal histidine. Furthermore, the binding properties depend on the presence of an internal disulfide bond. In the case of human neuroglobin, cysteines at positions CD7 and D5 are sufficiently close to form an internal disulfide bond. For cytoglobin, the cysteine residues at positions A7 and GH4 may also form a disulfide bond. Mass spectrometry, ligand binding, and thiol accessibility studies were used to study the role influence of these disulfide bonds. Mutation of specific cysteines, or reduction to break the S-S bond, led to a large decrease in the observed oxygen affinity of human neuroglobin, mainly due to a decrease in the histidine dissociation rate. This suggests a novel mechanism for the oxygen binding; reduction of the disulfide bond would provoke the release of oxygen.

Neuroglobin ligand binding kinetics.

Neuroglobin, cytoglobin, and hemoglobins from Drosophila melanogaster and Arabidopsis thaliana were studied for their ligand binding properties versus temperature. These globins have a common feature of being hexacoordinated (via the distal histidine) under deoxy conditions, displaying and enhanced amplitude for the alpha absorption band at 560 nm. External ligands can bind, but the transition from the hexacoordinated form to the ligand (L) bound species is slow, as expected for a replacement reaction Fe-His <--> Fe <--> Fe-L. Histidine binding is on the order of 1 ms; dissociation times are variable, and may be as long as 1 s for the highest histidine affinities. Oxygen binds rapidly but dissociates slowly, requiring as much as 1 s. These rates would correspond to a very high affinity for the pentacoordinated form; however, competition with the distal histidine leads decreases the affinity for the external ligand. The observed oxygen affinity remains in the range of 1 to 10 mm Hg. The low oxygen dissociation indicates a stabilization via H-bonds as for certain globins from parasites (Ascaris, the trematodes). Other ligands such as CO, or CN for the ferric form, show a decreased affinity, since only the competition with the E7 histidine, but not the stabilizing H-bond, plays a role. In addition, the competitive internal ligand leads to a weaker observed temperature dependence of the ligand affinity, since the difference in equilibrium energy for the two ligands is much lower than that of ligand binding to pentacoordinated hemoglobin. This effect could be of biological relevance for certain organisms, since it would lead to an oxygen affinity that is nearly independent of temperature.

The redox state of the cell regulates the ligand binding affinity of human neuroglobin and cytoglobin.

Neuroglobin and cytoglobin reversibly bind oxygen in competition with the distal histidine, and the observed oxygen affinity therefore depends on the properties of both ligands. In the absence of an external ligand, the iron atom of these globins is hexacoordinated. There are three cysteine residues in human neuroglobin; those at positions CD7 and D5 are sufficiently close to form an internal disulfide bond. Both cysteine residues in cytoglobin, although localized in other positions than in human neuroglobin, may form a disulfide bond as well. The existence and position of these disulfide bonds was demonstrated by mass spectrometry and thiol accessibility studies. Mutation of the cysteines involved, or the use of reducing agents to break the S-S bond, led to a decrease in the observed oxygen affinity of human neuroglobin by an order of magnitude. The critical parameter is the histidine dissociation rate, which changes by about a factor of 10. The same effect is observed with human cytoglobin, although to a much lesser extent (less than a factor of 2). These results suggest a novel mechanism for the regulation of oxygen binding; contact with an appropriate electron donor would provoke the release of oxygen. Hence the oxygen affinity would be directly linked to the redox state of the cell.