Modelling auxin efflux carrier phosphorylation and localization.

Regulation of the activity and localization of PIN-FORMED (PIN) membrane proteins, which facilitate efflux of the plant hormone auxin from cells, is important for plants to respond to environmental stimuli and to develop new organs. The protein kinase PINOID (PID) is involved in regulating PIN phosphorylation, and this is thought to affect PIN localization by biasing recycling towards shootwards (apical) (rather than rootwards (basal)) membrane domains. PID has been observed to undergo transient internalization following auxin treatment, and it has been suggested that this may be a result of calcium-dependent sequestration of PID by the calcium-binding protein TOUCH3 (TCH3). We present a mathematical formulation of these processes and examine the resulting steady-state and time-dependent behaviours in response to transient increases in cytosolic calcium. We further combine this model with one for the recycling of PINs in polarized cells and also examine its behaviour. The results provide insight into the behaviour observed experimentally and provide the basis for subsequent studies of the tissue-level implications of these subcellular processes for phenomena such as gravitropism.

Inhibition of quorum sensing in a computational biofilm simulation.

Bacteria communicate through small diffusible molecules in a process known as quorum sensing. Quorum-sensing inhibitors are compounds which interfere with this, providing a potential treatment for infections associated with bacterial biofilms. We present an individual-based computational model for a developing biofilm. Cells are aggregated into particles for computational efficiency, but the quorum-sensing mechanism is modelled as a stochastic process on the level of individual cells. Simulations are used to investigate different treatment regimens. The response to the addition of inhibitor is found to depend significantly on the form of the positive feedback in the quorum-sensing model; in cases where the model exhibits bistability, the time at which treatment is initiated proves to be critical for the effective prevention of quorum sensing and hence potentially of virulence.

Symptoms and signs in patients with colorectal cancer.

The symptoms and signs of colorectal cancer vary from the general population to primary care and in the referred population to secondary care. This review aims to address the diverse symptoms, signs and combinations with relevance to colorectal cancer at various points in the diagnostic pathway and tries to shed light on this complex and confusing area. A move towards a lower threshold for referral and increased use of diagnostics might be a more reliable option for early diagnosis.

Tortuosity in movement paths is related to cognitive impairment. Wireless fractal estimation in assisted living facility residents.

BACKGROUND: Using traditional assessment procedures, prior research demonstrated that deficiencies in gait and balance occur in the later stages of dementia. OBJECTIVE: We tested the hypothesis that an automated system capable of detecting path tortuosity (irregular movement) in elders would show that greater tortuosity was associated with greater cognitive impairment, potentially allowing early detection of dementia over time as tortuosity levels slowly increased. METHODS: An ultra-wideband sensor network using wireless transponders measured daytime locomotion to an accuracy of 20 cm in 14 elderly residents in an assisted living facility (ALF) as they traversed a shared living area while performing daily activities such as going to a dining area, conversing and watching television. Transponder location was updated at 0.4 sec intervals while in motion and revealed large individual differences in activity patterns. RESULTS: Fractal dimension (Fractal D), a measure of movement path tortuosity (directed vs. irregular or apparently aimless locomotion) was significantly and negatively correlated with cognitive status as measured by the Mini Mental State Examination administered to each participant at the study's end. CONCLUSIONS: Previous studies of locomotion in laboratory settings that have demonstrated gait variability increases with poor cognitive status have necessarily controlled various components of gait. The present results demonstrate that directional changes and other locomotion components can be studied by monitoring free movements in normal living settings over time. Implications for assessment and management of dementia-related wandering are discussed.

Continuum approximations of individual-based models for epithelial monolayers.

This work examines a 1D individual-based model (IBM) for a system of tightly adherent cells, such as an epithelial monolayer. Each cell occupies a bounded region, defined by the location of its endpoints, has both elastic and viscous mechanical properties and is subject to drag generated by adhesion to the substrate. Differential-algebraic equations governing the evolution of the system are obtained from energy considerations. This IBM is then approximated by continuum models (systems of partial differential equations) in the limit of a large number of cells, N, when the cell parameters vary slowly in space or are spatially periodic (and so may be heterogeneous, with substantial variation between adjacent cells). For spatially periodic cell properties with significant cell viscosity, the relationship between the mean cell pressure and length for the continuum model is found to be history dependent. Terms involving convective derivatives, not normally included in continuum tissue models, are identified. The specific problem of the expansion of an aggregate of cells through cell growth (but without division) is considered in detail, including the long-time and slow-growth-rate limits. When the parameters of neighbouring cells vary slowly in space, the O(1/N(2)) error in the continuum approximation enables this approach to be used even for modest values of N. In the spatially periodic case, the neglected terms are found to be O(1/N). The model is also used to examine the acceleration of a wound edge observed in wound-healing assays.

Role of sphingosine-1-phosphate (S1P) and the S1P(2) receptor in allergen-induced, mast cell-dependent contraction of rat lung parenchymal strips.

Lung parenchymal strips isolated from ovalbumin-sensitized rats manifest a mast cell-dependent, biphasic contraction when challenged with allergen. The first phase is mediated by the release of preformed 5-HT while the second phase is dependent on de novo synthesis of leukotrienes. Sphingosine 1-phosphate (S1P) is a sphingolipid metabolite which is readily generated in mast cells and has been demonstrated to be an important regulator of allergen-induced mast cell activation. We have used the parenchymal strip to explore the role of sphingosine 1-phosphate and the S1P(2) receptor in the two components of the acute response to allergen. Lung parenchymal strips were prepared from Brown Norway rats actively sensitized to ovalbumin. The strips were set up in organ baths and contractile responses measured isometrically. The inhibitors of sphingosine kinase, D-erythro-NN-dimethylsphingosine (dimethylsphingosine) and 4-[4-(4-chloro-phenyl)-thiazol-2-ylamino]-phenol (SKI-II) inhibited concentration-dependently both phases of the contractile response induced by 0.1 microg ml(-1) ovalbumin. The effects were seen at concentrations similar to those which inhibit the purified enzyme and were selective in that neither the contractile response to adenosine nor that to 5-hydroxytryptamine was affected. JTE-013 (a selective S1P(2) receptor antagonist) also blocked the response to ovalbumin (0.1 microg ml(-1)). However, the concentrations of JTE-013 required (microM) were substantially higher than its affinity for the S1P(2) receptors (nM). However, when tested against a lower concentration of ovalbumin (0.03 microg ml(-1)), JTE-013 inhibited the response with nM potency. These data demonstrate the importance of S1P and the S1P(2) receptor as regulators of allergen-induced activation of mast cells in their natural environment in the rat lung.

In vivo pharmacological evaluation of compound 48/80-induced airways oedema by MRI.

BACKGROUND AND PURPOSE: Allergen-induced airways oedema in actively sensitized rats has been studied earlier by magnetic resonance imaging (MRI). We used MRI to follow the consequences of non-immunological mast cell activation induced by compound 48/80 in the rat lungs in vivo. EXPERIMENTAL APPROACH: Male naïve rats were scanned by MRI prior to and at several time points following intratracheal administration of the mast cell secretagogue, compound 48/80. The effects of a range of drugs on the response induced by compound 48/80 were studied. KEY RESULTS: Strong fluid signals were detected by MRI in the lungs at 24 h after compound 48/80, correlating with increased protein concentration and inflammatory cell infiltration in bronchoalveolar lavage, and with perivascular oedema observed histologically. Pharmacological intervention demonstrated that the increase in MRI signal volume induced by compound 48/80 24 h after challenge was blocked by disodium cromoglycate and the glucocorticoid, budesonide. Pretreatment with wortmannin, capsazepine, DNK333 (a dual neurokinin (NK) 1 and NK2 antagonist) or the anti-allergy drug CGS8515, but not indomethacin, resulted in partial inhibition. CONCLUSIONS AND IMPLICATIONS: Compound 48/80 induced a complex inflammatory reaction which did not solely involve mast cell degranulation but also activation of sensory nerves and was qualitatively similar to allergen challenge. Changes observed by MRI correlated with decreases in protein concentration in BAL fluid. However, the magnitude of the changes detected was greater using MRI. Our results demonstrate that MRI is a sensitive and efficient tool to assess the effects of drugs on lung inflammation.

Validation of the lower gastrointestinal electronic referral protocol.

BACKGROUND: Recognition of people presenting to the general practitioner with symptoms suggestive of colorectal cancer varies considerably, as do the subsequent patterns of referral and treatment. The Lower Gastrointestinal Electronic Referral Protocol (e-RP) was developed to be used alongside the national Choose and Book programme. This paper addresses the validation of the e-RP. METHODS: The e-RP was validated using three datasets: 100 consecutive patients with colorectal cancer, 100 2-week wait (TWW) suspected cancer referrals and 100 routine referrals. The actual destination of referred patients, their clinical diagnosis and referral urgency were compared with destination and referral urgency assigned by the e-RP. RESULTS: Some 43.0 per cent of patients with colorectal cancer were actually referred through the TWW system and the e-RP successfully upgraded 85.0 per cent of these patients as TWW referrals (Pearson chi(2) = 9.76, 1 d.f., P = 0.002). The e-RP also redirected three of four patients with colorectal cancer in routine referrals to TWW clinics. Right-sided cancers were appropriately directed to colonoscopy as the first contact in secondary care or to outpatients for investigation of a palpable mass. Most patients with left-sided cancers were directed to flexible sigmoidoscopy clinics. CONCLUSION: A dedicated referral protocol addressing all colorectal symptoms would significantly improve the overall yield of colorectal cancers through the TWW route and reduce delays in patient pathways with 'straight to test' in secondary care.

Inter general practice variability in use of referral guidelines for colorectal cancer.

OBJECTIVE: The Two-Week Wait (TWW) referral system for suspected colorectal cancers has a low yield. To examine this, we assessed the referral pattern of general practices within four primary care trusts and looked at the variability of yield of colorectal cancer amongst all TWW referrals and assessed the reasons for variability. METHOD: A prospectively collected database of all colorectal cancers was examined for new cases diagnosed in the 12 months from April 1st 2004. Patients were cross-referenced via general practitioner (GP) codes to identify the referral origin. Reasons for the variability in referral patterns from each general practice were assessed in relation to TWW referrals, population demographics and through postal questionnaire of GPs. RESULTS: A total of 175 patients diagnosed with colorectal cancer were referred from 49 general practices. Whilst there was a positive correlation between the number of TWW referrals and colorectal cancer per 1000-practice population (P = 0.001; Spearman correlation coefficient r(s=0.447,) two-tailed), there was a big discrepancy between referrals and cancer diagnosed in many general practices. Twenty-six general practices (53%) had no colorectal cancer diagnosed via the TWW route and these practices had significantly lower utilization of the TWW referral pathway. In the postal survey, 22% of GPs were unaware of TWW clinics or colorectal cancer referral guidelines and only 8% of GPs knew the number of referral criteria. CONCLUSION: This study demonstrates wide variability within primary care, in the appropriate use of colorectal cancer referral guidelines. General practices should be targeted for education.

Should we pursue patients who fail to attend colorectal clinics? A 9-year study.

INTRODUCTION: No uniform protocol exists on how to deal with patients who fail to attend colorectal clinics. Our aim was to identify whether the tendency to 'failure to attend' (FTA) in the colorectal clinic was associated with FTA in other clinics and also whether FTA patients have serious pathology. PATIENTS AND METHODS: This was a retrospective study of a prospectively recorded list of FTA patients, in colorectal urgent or two-week wait clinics from 1996-2004. RESULTS: A total of 151 patients, who failed to attend their first appointment, were included in the study. Of these, 61 (40.4%) were colorectal referrals, 76 (50.3%) were general surgical referrals, and for 14 (9.3%) case notes were not available. There were 59 FTA episodes in 61 colorectal patients associated with 59 FTA episodes in other clinics (Pearson correlation: r = 0.411; P = 0.01, two-tailed, SPSS v.12). Of 58 colorectal outcomes, five (8.6%) colorectal cancers (CRC) were diagnosed, 23 (39.6%) were persistent non-attendees, 16 (27.5%) had benign colorectal pathology, two (3.4%) benign non-colorectal outcomes and 12 (20.6%) normal outcomes. CONCLUSIONS: Tendency to FTA is habitual. Care needs to be exercised in the management of FTAs to avoid delayed presentation of colorectal cancer.

Long-term survival is possible after stenting for malignant ureteric obstruction in colorectal cancer.

INTRODUCTION: Ureteric obstruction is a potentially terminal event in patients with irresectable or recurrent colorectal cancer. Urinary tract obstruction is easily relieved by either two stage antegrade stenting or one stage retrograde stenting. However, there is little in the literature about outcomes after this procedure and it is unclear which, if any, patients should be offered this intervention. PATIENTS AND METHODS: This was a retrospective review of a prospectively collected database of patients diagnosed with colorectal cancer. This database comprised 1428 cases (operative and non-operative) diagnosed at a single institution. This was cross-checked with databases for patients undergoing nephrostomy and/or antegrade stenting and by clinical coding for those patients having retrograde stenting between January 1996 and October 2004. RESULTS: Thirteen patients were identified (median age, 69 years: range, 35-85 years; 9 male). The aetiology of obstruction was recurrent tumour in 6 patients and irresectable tumour in the remaining 7 patients. Two patients were discussed at a urology multidisciplinary meeting before stenting and a further two were discussed with colorectal surgeons. One patient received a palliative cystectomy and ileal conduit for a vesicovaginal fistula followed by radiotherapy. Four patients received chemotherapy after stenting. Overall median survival was 210 days (range, 13-927 days). CONCLUSIONS: Long-term survival is possible in selected patients with recurrent or irresectable colorectal cancer and malignant ureteric obstruction. This appears to be more likely in those patients in whom other treatments, particularly chemotherapy, are available.

Low anastomotic leak rate after colorectal surgery: a single-centre study.

OBJECTIVE: Anastomotic leak after colorectal surgery is a serious event associated with significant morbidity and mortality. There is little consensus regarding 'acceptable' rates of leakage, however. This study describes the experience of anastomotic leakage after both elective and emergency colorectal surgery in a district general hospital. METHOD: A prospectively collected database of all patients with a diagnosis of colorectal cancer in a single hospital formed the basis of the study. Leak was defined as breakdown of the anastomosis contributing to death or requiring reoperation or reintervention. RESULTS: A total of 949 patients underwent surgery with an anastomosis between 1996 and 2004, including 331 patients treated with anterior resection. Anastomotic leaks requiring reoperation occurred in eight patients (0.8%). Thirty-day and in-hospital mortality was 4%. CONCLUSION: A very low rate of anastomotic leakage after colorectal surgery is possible in a district general hospital setting. Given the impact of anastomotic leakage on function, tumour recurrence and long-term survival, it should be considered as a marker of surgical quality when evaluating surgical performance.

Capsaicin-induced mucus secretion in rat airways assessed in vivo and non-invasively by magnetic resonance imaging.

BACKGROUND AND PURPOSE: An up-regulation of the sensory neural pathways in the lung has been implicated in asthma and chronic obstructive pulmonary disease (COPD) and is thought to contribute to mucus hypersecretion, an essential feature of both diseases. The aim of this study was to assess non-invasively the acute effects (up to 60 min) of sensory nerve stimulation by capsaicin in the lung, using magnetic resonance imaging (MRI). EXPERIMENTAL APPROACH: Male Brown Norway rats were imaged prior to and 10, 30 and 60 min after intra-tracheal challenge with capsaicin (30 microg kg(-1)) or vehicle (0.5% ethanol solution). In subsequent studies, pre-treatment with the transient receptor potential vanilloid (TRPV)-1 antagonist, capsazepine; the dual neurokinin (NK) 1 and NK2 receptor antagonist, DNK333 and the mast cell stabilizer, di-sodium cromoglycate (DSCG) was used to modulate the effects of capsaicin. KEY RESULTS: Diffuse fluid signals were detected by MRI in the lung as early as 10 min after capsaicin, remaining constant 30 and 60 min after treatment. Broncho-alveolar lavage (BAL) fluid analysis performed 60 min after capsaicin revealed increased mucin concentration. Capsazepine (3.5 mg kg(-1)), DNK333 (10 mg kg(-1)) but not DSCG (10 mg kg(-1)) administered prophylactically were able to block the effect of capsaicin in the airways. CONCLUSIONS AND IMPLICATIONS: These observations suggest that the fluid signals detected by MRI after capsaicin administration reflected predominantly the release of mucus following activation of sensory nerves. They point to the opportunity of non-invasively assessing with MRI the influence of neuronal mechanisms in animal models of asthma and COPD.

Cause and place of death in patients dying with colorectal cancer.

OBJECTIVE: Few studies on colorectal cancer look at the one-third of patients for whom treatment fails and who need a management strategy for death. This paper has examined the mode and place of death in patients with colorectal cancer. METHOD: This study was a review of 209 deaths, analysed between January 2001 and September 2004 by retrospective review of a prospectively collected database. RESULTS: A total of 118 patients (group 1) had undergone resection of their primary colorectal cancer, 20 (group 2) had had a defunctioning stoma or bypass surgery and the remaining 71 patients (group 3) had either had no surgery, an open and close laparotomy or had a colonic stent. One hundred and fifty-six (75%) patients died of colorectal cancer with the remainder dying of other causes. The number of admissions to hospital and the number of days spent in hospital from diagnosis to death were greatest in group 1. Overall, only 34 patients (22%) dying from colorectal cancer died at home. Forty (26%) died in hospital and 70 (45%) died in a palliative care unit. CONCLUSIONS: Patients dying from colorectal cancer who undergo surgical resection of their primary tumour spend more time between diagnosis and death in hospital. They are also more likely to die in hospital than patients treated by surgical palliation or nonsurgically. Patients who are treated palliatively from the outset (group 3) are most likely to die at home. If hospital is accepted as an appropriate place for death from colorectal cancer, then greater provision for this should be made.

Effects of endotoxin and allergen alone and in combination on the sensitivity of the rat airways to adenosine.

1 The airways of patients with asthma are hyperresponsive to adenosine. The phenomenon can be mimicked in the actively sensitized Brown Norway rat by exposure to allergen or lipopolysaccharide (LPS). We wondered whether combined treatment with allergen and endotoxin would result in additive effects or synergism with respect to increasing the sensitivity of the airways of the Brown Norway rat to adenosine. 2 Animals actively sensitized to ovalbumin and challenged intratracheally with allergen or endotoxin manifested increased bronchoconstrictor responses to adenosine. A combination of ovalbumin and endotoxin also increased the response to adenosine but the effects were at best additive. 3 Changes in the response to adenosine were selective as responses to 5-hydroxytryptamine were unaltered following ovalbumin or LPS either alone or in combination. 4 Thus, endotoxin and allergen acting together could play a role in up-regulating the response of the human asthmatic airway to adenosine. However, our data suggest that the interaction would be additive rather than synergistic.

Suppression of histamine-induced tachypnoea in the rhesus monkey by sibenadet: no role for dopamine D2 receptors.

1. Sibenadet (Viozan), a dual dopamine D(2)/beta(2)-adrenoceptor agonist, suppresses histamine-induced tachypnoea in the dog by activating dopamine D(2) receptors. We here compare the effects of sibenadet and formoterol, a selective beta(2)-adrenoceptor agonist, on histamine-induced tachypnoea in the rhesus monkey. 2. Anaesthetized, spontaneously breathing, rhesus monkeys were set up for measuring airways resistance, respiratory rate, blood pressure and heart rate. 3. Both sibenadet and formoterol administered by aerosol, induced inhibition of the bronchoconstrictor response to aerosolized methacholine accompanied by tachycardia. Sibenadet, but not formoterol, also reduced blood pressure. 4. Administration of histamine by inhalation induced tachypnoea which was accompanied by bronchoconstriction. Tachypnoea to histamine was suppressed by both sibenadet and formoterol at doses which manifest anti-bronchoconstrictor activity. These effects and the accompanying tachycardia but not the hypotension induced by sibenadet were abolished by pretreatment with propranolol. 5. The dopamine D(2) receptor agonist, quinagolide, did not suppress tachypnoea to histamine despite inducing a fall in blood pressure indicating activation of dopamine D(2) receptors. 6. Thus, both sibenadet and formoterol suppress histamine-evoked tachypnoea in the rhesus monkey. The effect arises exclusively through activation of beta(2)-adrenoceptors and probably reflects the anti-bronchoconstrictor effects of these agents. The results reveal a fundamental difference in the role of dopamine receptors in the airways of dog and rhesus monkey.

Airway hyperresponsiveness to bradykinin induced by allergen challenge in actively sensitised Brown Norway rats.

The mechanism(s) of bradykinin-induced bronchoconstriction was investigated in the Brown Norway (BN) rat model of allergic asthma. Bronchoconstrictor responses to i.v. bradykinin in BN rats were maximally augmented 24 h following challenge with allergen and declined at later time points. Histological evaluation of the inflammatory status of the lungs after ovalbumin (OA) challenge showed a marked inflammatory response, which was maximal at 24 h and declined thereafter. However, pretreatment with budesonide did not inhibit the augmented bronchoconstrictor response to bradykinin 24 h after allergen challenge. The selective B1 receptor agonist, Lys-[desArg9]-BK had no bronchoconstrictor effects, whereas the selective B2 receptor antagonist, HOE 140, abolished the response to bradykinin in OA-challenged animals. The augmented response to bradykinin was not affected by methysergide, indomethacin, disodium cromoglycate, iralukast, the 5-lipoxygenase inhibitor, CGS8515, or the NK2 receptor antagonist, SR48968. It was, however, partially inhibited by atropine both in saline- and OA-challenged animals. Pretreatment with captopril and thiorphan markedly potentiated responses to bradykinin both in saline- and OA-challenged animals. Thus, augmentation of the bronchoconstrictor response to bradykinin occurs in actively sensitised BN rats 24 h after challenge with OA and is associated with marked pulmonary inflammation. The response is entirely B2 receptor mediated and approximately 50% of the response is cholinergic. However, mast cell activation, the products of the cyclooxygenase or 5-lipoxygenase pathways and tachykinins are not involved. Peptidase inhibition mimics the effect of allergen challenge on the bronchoconstrictor response to bradykinin and it remains possible that the mechanism of the augmented response to bradykinin following allergen challenge involves downregulation of peptidase activity as a consequence of the inflammatory response.

Per-anal excision of large, rectal, villous adenomas.

PURPOSE: Considering the malignant potential of villous adenoma of the rectum, complete resection at the first intervention is desirable and yet many series suggest that a high recurrence rate must be expected. The experience of one colorectal surgeon in the management of this condition is described. METHODS: Between 1993 and 2000, 50 patients underwent per-anal resection of villous adenoma. The procedure was conducted in the prone jackknife position unless contraindicated, with dissection performed using a diathermy blade, with particular attention to circumferential and deep margins of excision. RESULTS: The mean distance of the proximal margin of the tumor from the dentate line was 5.6 (range, 0.5-11) cm. The mean length of the tumor was 5.2 (range, 0.5-9) cm. Mean anesthetic time was 27 (range, 10-110) minutes, and median hospital stay was two (range, 1-14) days. There was no significant perioperative morbidity and no mortality. On histology of ten patients, there were foci of adenocarcinoma. Excision was complete histologically in 49 patients. The median follow-up was 30 (range, 6-91) months. The patient with incomplete excision developed a probable recurrence after six months, which was ablated with diathermy (residual tumor rate, 2.1 percent). Two patients have subsequently developed villous adenoma at different sites within the rectum (metachronous tumor rate, 4.3 percent). CONCLUSIONS: Many series of this procedure report recurrence in up to 36 percent and significant complication in up to 19 percent of patients. Transanal endoscopic microsurgery has achieved recurrence rates of 2.8 percent and low complication rates but for economic reasons has failed to find a widespread role. This article demonstrates that large, villous tumors of the low and mid rectum can be simply and effectively treated by per-anal resection with recurrence rates equivalent to transanal endoscopic microsurgery.