Using staged teaching and assessment approaches to facilitate inter-university collaboration and problem-based learning

This article describes the segmented module design and problem-based learning approaches employed to enable parts of a higher education environmental health module (course) to be shared between universities in Wales, Northern Ireland, and Australia. The module requires students to identify the needs and assets of a community then design community-based interventions to address problems and undertake an evaluation of those interventions. Accreditation body and the degree program learning outcome requirements in the UK and Australia were found to hold many comparable knowledge, skills, and graduate attribute criteria, eliminating a potential barrier for international learning and teaching collaboration between higher education institutions. Instead, barriers to collaboration were associated with institutional issues and practicalities such as timetabling and assessment requirements. Taking a segmented approach to module design allowed staged and varied levels of collaboration between participating institutions, all delivering modules (courses) with similar learning outcomes. This provided a more sustainable environment to facilitate shared learning and teaching and fostered closer relations between programs, within these constraining factors. Students using problem-based learning and its group-working component exhibited the development of leadership, communication, and independent learning skills.

Short‐ and long‐term outcomes of polyethylene band attenuation of congenital extrahepatic portosystemic shunts in dogs: 60 cases (2010‐2020)

OBJECTIVES

To report the short- and long-term outcomes following attenuation of congenital extrahepatic portosystemic shunts in dogs using a novel polyethylene band.

MATERIALS AND METHODS

Records were retrospectively reviewed for dogs that underwent congenital extrahepatic portosystemic shunt attenuation by a polyethylene banding technique, at a single institution between 2010 and 2020. Short-term outcome data were collected from peri-operative clinical records with follow-up examinations, scheduled at 6 and 18 weeks post-operatively, and post-operative imaging when performed. Long-term follow-up was collected by validated owner questionnaire, telephone interview or medical records. Long-term outcomes were categorised by "excellent", "good" or "poor".

RESULTS

Sixty dogs were included. Post-operative complications occurred in 10 of 60 dogs (16.7%), four major and six minor, with a peri-operative mortality of 6.7%. Persistent shunting was identified in nine of 53 dogs (17%) available for follow-up examination and four dogs underwent a revision surgery. Long-term follow-up was available for 44 dogs at a median of 75 months post-operatively (range 7 to 128). Long-term outcomes were "excellent" (26) or "good" (8) in 81.8% of dogs and "poor" (8) in 18.2%. At the time of follow-up, 30 of 44 (68.2%) dogs were not receiving any medical treatment and 27 of 28 (96.4%) questionnaire respondents were satisfied with the response to surgery.

CLINICAL SIGNIFICANCE

Polyethylene band attenuation of congenital extrahepatic portosystemic shunts provides comparable outcomes to cellophane. The material used in this study is widely available and consistent while being pre-sterilised and pre-folded makes it easy to use.

Comparing hospital and telephone follow-up for patients treated for stage-I endometrial cancer (ENDCAT trial): a randomised, multicentre, non-inferiority trial

OBJECTIVE

To evaluate the effectiveness of nurse-led telephone follow-up (TFU) for patients with stage-I endometrial cancer.

DESIGN

Multicentre, randomised, non-inferiority trial.

SETTING

Five centres in the North West of England.

SAMPLE

A cohort of 259 women treated for stage-I endometrial cancer attending hospital outpatient clinics for routine follow-up.

METHODS

Participants were randomly allocated to receive traditional hospital based follow-up (HFU) or nurse-led TFU.

MAIN OUTCOME MEASURES

Primary outcomes were psychological morbidity (State Trait Anxiety Inventory, STAI-S) and patient satisfaction with the information provided. Secondary outcomes included patient satisfaction with service, quality of life, and time to detection of recurrence.

RESULTS

The STAI-S scores post-randomisation were similar between groups [mean (SD): TFU 33.0 (11.0); HFU 35.5 (13.0)]. The estimated between-group difference in STAI-S was 0.7 (95% confidence interval, 95% CI -1.9 to 3.3); the confidence interval lies above the non-inferiority limit (-3.5), indicating the non-inferiority of TFU. There was no significant difference between groups in reported satisfaction with information (odds ratio, OR 0.9; 95% CI 0.4-2.1; P = 0.83). Women in the HFU group were more likely to report being kept waiting for their appointment (P = 0.001), that they did not need any information (P = 0.003), and were less likely to report that the nurse knew about their particular case and situation (P = 0.005).

CONCLUSIONS

The TFU provides an effective alternative to HFU for patients with stage-I endometrial cancer, with no reported physical or psychological detriment. Patient satisfaction with information was high, with similar levels between groups.

TWEETABLE ABSTRACT

ENDCAT trial shows effectiveness of nurse-led telephone follow-up for patients with stage-I endometrial cancer.

Tear physiology in dry eye associated with chronic GVHD

The purpose of this study was to compare tear physiology characteristics of chronic GVHD (cGVHD)-associated dry eye to dry eye caused by Sjogren's syndrome (SS), a extreme form of aqueous-deficient dry eye, and meibomian gland dysfunction (MGD), the major cause of evaporative dry eye. Tear turnover rate, evaporation and osmolarity along with meibomian gland dropout and lipid layer interferometric patterns were assessed in the right eyes of 12 patients with dry eye associated with cGVHD, 12 age-matched patients with SS and 12 age-sex matched subjects with MGD. In cGVHD, the decrease in tear turnover rate was similar (P=0.33), but the number of non-functioning meibomian glands was significantly higher (P<0.01) than in SS. Tear evaporation rate in cGVHD dry eye was found to be similar to that in MGD (P=0.36) and significantly higher than in SS (P<0.01). The lipid layer was most unstable in cGVHD compared with other groups. There was no variation in tear volume across all groups. Although statistical significance was not detected, the mean tear osmolarity (333.51±14.67mOsm/L) was highest in cGVHD. Major aspects of tear physiology were severely impaired in cGVHD-associated dry eye.

Neuronal differentiation in Drosophila ommatidium

Using monoclonal and polyclonal antibodies as differentiation markers, we have found that the eight photoreceptors of the Drosophila ommatidium differentiate in a fixed sequence. The foundation photoreceptor, R8, expresses neural antigens first. The paired photoreceptors R2/5 are next to express, followed by the pair R3/4, followed by the pair R1/6; R7 is the final photoreceptor to differentiate. From previous studies it is known that Drosophila photoreceptors use local, positional cues to select their identities. Together with the morphological picture of ommatidial development, the sequential order of photoreceptor differentiation demonstrated here suggests that these cues may be encoded in the particular combination of cells an undetermined cell finds itself in contact with.

Cellular communication in the developing Drosophila eye

Undetermined cells are directed to their fate in the Drosophila eye by positional cues which are probably presented by adjacent differentiating cells. The sevenless protein is thought to function as a signal-receiving protein on the plasma membrane of the cell destined to form the seventh photoreceptor, R7. Localization of the protein indicates the interactions between undetermined and differentiating cells and suggests the existence of other receptor proteins similar to sevenless.

The comparative diagnostic accuracy of conventional and liquid-based cytology in a colposcopic setting

OBJECTIVE

This study was conducted to compare the performance of liquid-based cytology (LBC) and conventional cytology (CS) in the high prevalence setting of colposcopy clinic.

DESIGN

A split sample of matched ThinPrep (TP) and conventional smear from 563 patients were evaluated blindly. The performance of both techniques was compared with the gold standard of biopsy results or normal colposcopy examination in 441 cases.

SETTING

Colposcopy clinic of an inner city hospital for women and children.

SAMPLE

Five hundred and sixty-three women referred to colposcopy clinic over 14-month period.

METHODS

Cervical smears were taken from 563 women referred for colposcopy. Using the split-sample technique, the material was spread on a conventional (CS) slide and the remaining material rinsed in a PreservCyt solution. A T2000 processor was used to prepare LBC preparations. All women underwent colposcopy/biopsy according to local protocol. Four hundred and forty-one women met the diagnostic standard criteria of the study, which was either a normal colposcopy or histopathology result. Sensitivity, specificity and positive and negative predictive values were calculated for both methods of cytology preparations.

MAIN OUTCOME MEASURES

Matched TP and conventional smears, detection of abnormality, matched biopsies, sensitivity, specificity, and positive and negative predictive values.

RESULTS

Inadequate rates for CS and LBC (TP) were 4.3% and 0.68%, respectively. In 73% of cases, the CS and the LBC preparations showed exact agreement, whereas 77% agreement was seen when comparison was made for amalgamated low grade and high grade abnormalities. Low grade cytological abnormalities accounted for 44% of LBC slides versus 37% in CS slides. High grade cytological abnormalities accounted for 22% of LBC versus 17% seen in CS cases (P < 0.001). LBC showed increased sensitivity in the detection of CIN2 or worse than CS (92% and 83%, respectively) and CS showed greater specificity than LBC (82% and 76%, respectively).

CONCLUSIONS

In high prevalence setting, LBC performed at least as well as CS. The inadequate rate was significantly lower with LBC. The numbers are too small, however, to make confident comments about increased sensitivity and negative predictive value with LBC. Larger studies are required to verify these findings.

Visualizing the photonic band gap in hollow core photonic crystal fibers

The light radiated from the guided mode of a hollow core photonic crystal fiber into free space is measured as a function of angle and wavelength. This enables the direct experimental visualization of the photonic band gap and the identification of localized modes of the core region.

Ultimate low loss of hollow-core photonic crystal fibres

Hollow-core photonic crystal fibres have excited interest as potential ultra-low loss telecommunications fibres because light propagates mainly in air instead of solid glass. We propose that the ultimate limit to the attenuation of such fibres is determined by surface roughness due to frozenin capillary waves. This is confirmed by measurements of the surface roughness in a HC-PCF, the angular distribution of the power scattered out of the core, and the wavelength dependence of the minimum loss of fibres drawn to different scales.

Does improving communication and information for women increase attendance at colposcopy in an inner city clinic? A randomised controlled trial

PURPOSE

To establish whether information leaflets and appointment reminders improve attendance for diagnostic colposcopy.

DESIGN & SETTING

Randomised controlled trial in an inner city colposcopy clinic.

PARTICIPANTS

500 women newly referred to the colposcopy clinic with abnormal cervical screening smear results were randomly assigned to an intervention or control group using computer-generated numbers.

INTERVENTION

233 women referred for colpoposcopy were sent a comprehensive information leaflet with their appointment details and additionally were sent reminder letters regarding their appointment 7-10 days prior to their appointment date.

CONTROL

267 women were sent the standard basic information prior to their appointment.

MAIN OUTCOME MEASURE

Attendance and default rates for diagnostic colposcopy.

RESULTS

Default in the intervention arm was 42 out of 233 (18%) compared with 93 out of 267 (35%) in the control arm.

CONCLUSION

Improved communication and information in the form of a detailed leaflet and a reminder letter for women with a recently abnormal smear result increased attendance for initial colposcopy assessment.

ISABEL: a web-based differential diagnostic aid for paediatrics: results from an initial performance evaluation

AIMS

To test the clinical accuracy of a web based differential diagnostic tool (ISABEL) for a set of case histories collected during a two stage evaluation.

SETTING

acute paediatric units in two teaching and two district general hospitals in the southeast of England.

MATERIALS

sets of summary clinical features from both stages, and the diagnoses expected for these features from stage I (hypothetical cases provided by participating clinicians in August 2000) and final diagnoses for cases in stage II (children presenting to participating acute paediatric units between October and December 2000).

MAIN OUTCOME MEASURE

presence of the expected or final diagnosis in the ISABEL output list.

RESULTS

A total of 99 hypothetical cases from stage I and 100 real life cases from stage II were included in the study. Cases from stage II covered a range of paediatric specialties (n = 14) and final diagnoses (n = 55). ISABEL displayed the diagnosis expected by the clinician in 90/99 hypothetical cases (91%). In stage II evaluation, ISABEL displayed the final diagnosis in 83/87 real cases (95%).

CONCLUSION

ISABEL showed acceptable clinical accuracy in producing the final diagnosis for a variety of real as well as hypothetical case scenarios.

Transducing properties of Drosophila Frizzled proteins

In Drosophila, two closely related serpentine receptors, Frizzled (Fz) and D-Frizzled2 (Fz2) are able to act as receptors for the secreted Wnt peptide, Wingless (Wg). In addition to transducing the Wg signal, Fz (but not Fz2) is able to transduce a second, unidentified signal that mediates planar polarity. Much attention has been focused on the structure of the N-termini of the Fz-class receptors and their role in ligand binding. Experiments using techniques of high-level expression have suggested a role for the C-termini in specifying which of the two second messenger systems the receptors are able to activate (M. Boutros, J. Mihaly, T. Bouwmeeste and M. Mlodzik (2000). Science288, 1825-1828). We argue here that experiments involving high level expression of the receptors cannot be adequately interpreted and we have tested the ability of the receptors and chimeric forms when driven at moderate levels to rescue loss of function of the fz and fz2 genes. Under these conditions we find that all receptors tested will function as Wg receptors, but only a subset show the ability to rescue the polarity pathway. The presence of this subset implies that the N terminus is necessary but not sufficient and suggests that the ability to transduce the polarity signal is widely distributed throughout the protein.

Anterior Corneal Optical Aberrations Induced by Photorefractive Keratectomy for Hyperopia

PURPOSE

Photorefractive keratectomy (PRK) for hyperopia requires both a steepening of the central cornea and a flattening of the mid-periphery to achieve its effect and is likely to affect the optical aberrations of the eye.

METHODS

Nine patients underwent PRK to correct between +2.00 and +4.00 D of hyperopia (first eye treated for each patient) using the Summit Technology Apex Plus excimer laser. Anterior corneal aberrations for pupil diameters of 3, 5.5 and 7 mm were estimated from corneal topography data (TMS-1), assuming a uni-index, single surface cornea. Refractive error was assessed using retinoscopy and standard subjective tests.

RESULTS

Apart from the intended change in refraction (mean spherical equivalent manifest refraction, +4.60 +/- 1.60 D before surgery and +0.70 +/- 1.60 D at 1 year after surgery), the most significant change was in spherical aberration. Anterior corneal spherical aberration was positive (+1.60 +/- 0.60 D for a 5.5-mm pupil) before surgery and became negative after surgery (-1.80 +/- 1.20 D at 1 year). The change in spherical aberration was related to the achieved change in refractive error.

CONCLUSIONS

The large change (approximately 3.00 D) in spherical aberration (from positive to negative aberration) has implications for the optical performance of the whole eye, where the effects of lenticular aberration must also be considered.

Delta/Notch and Boss/Sevenless signals act combinatorially to specify the Drosophila R7 photoreceptor

The R7 photoreceptor, a unique cell type within the Drosophila ommatidium, was initially proposed to be specified by two distinct signals from neighboring cells, one from the R8 photoreceptor and another from the R1/6 photoreceptor pair. The R8-to-R7 signal is the transmembrane ligand Bride of Sevenless (Boss), which is received by the receptor tyrosine kinase Sevenless (Sev) and transduced via Ras activation within the presumptive R7 cell. However, the identity of the R1/6-to-R7 signal has remained elusive. Here, we present evidence that the transmembrane ligand Delta (Dl), expressed by the R1/6 pair, activates the receptor Notch (N) in the presumptive R7 cell and constitutes the postulated R1/6-to-R7 signal required in combination with the Boss/Sev signal to specify the R7 fate.

What does the phenol red thread test actually measure?

PURPOSE

This study attempts to resolve whether the phenol red thread test (PRT) is a test of tear volume or tear production through comparisons with other techniques.

METHODS

Twenty asymptomatic subjects (10 men and 10 women; average age 30.6 +/- 10.8 years) had PRT (Zone Quick, Menicon) results compared with tear turnover rate (by fluorophotometry; Fluorotron Master, OcuMetrics) and tear volumes (from tear meniscus height and back extrapolation from fluorometric data).

RESULTS

PRT wetting was not correlated with either tear turnover or volume (by fluorophotometry or tear meniscus height) on a Pearson product moment correlation test (p > 0.05).

CONCLUSIONS

No clear experimental evidence in favor of the PRT being a measure of tear production or volume was found. It is probable that the PRT measures uptake of a (small) amount of fluid residing in the eye, stimulates a low degree of reflex tearing, and reflects the absorption characteristics of the thread dependent on the biophysics or composition of tears.

Nitric oxide synthase inhibitors have opposite effects on acute inflammation depending on their route of administration

The bulk of published data has shown that NO is proinflammatory. However, there also exists the conflicting notion that NO may be protective during an inflammatory insult. In an attempt to resolve this issue, we have compared the effects on inflammation of a range of NO synthase (NOS) inhibitors given either directly to the site of the inflammatory lesion or systemically. It was found that in the carrageenin-induced pleurisy, a single intrapleural injection of the selective inducible NO inhibitors S-(2-aminoethyl) isothiourea (AE-ITU; 3 and 10 mg/kg) and N-(3-(aminomethyl)-benzyl) acetamidine (1400W; 10 mg/kg) or the selective endothelial cell NOS inhibitor L-N(5)(1-iminoethyl)-ornithine (10 mg/kg) not only exacerbated inflammation at the very early stages of the lesion (1-6 h), but also prevented inflammatory resolution. By contrast, administering NOS inhibitors systemically ameliorated the severity of inflammation throughout the reaction. To elucidate the mechanisms by which inhibition of NO synthesis locally worsened inflammation, we found an increase in histamine, cytokine-induced neutrophil chemoattractant, superoxide, and leukotriene B(4) levels at the inflammatory site. In conclusion, this work shows that the local production of NO is protective by virtue of its ability to regulate the release of typical proinflammatory mediators and, importantly, that NOS inhibitors have differential anti-inflammatory effects depending on their route of administration.

Symbiogenesis in learning classifier systems

Symbiosis is the phenomenon in which organisms of different species live together in close association, resulting in a raised level of fitness for one or more of the organisms. Symbiogenesis is the name given to the process by which symbiotic partners combine and unify, that is, become genetically linked, giving rise to new morphologies and physiologies evolutionarily more advanced than their constituents. The importance of this process in the evolution of complexity is now well established. Learning classifier systems are a machine learning technique that uses both evolutionary computing techniques and reinforcement learning to develop a population of cooperative rules to solve a given task. In this article we examine the use of symbiogenesis within the classifier system rule base to improve their performance. Results show that incorporating simple rule linkage does not give any benefits. The concept of (temporal) encapsulation is then added to the symbiotic rules and shown to improve performance in ambiguous/non-Markov environments.

Effect of oral contraceptives on tear physiology

Variations in sex hormones due to the menstrual cycle (and oral contraceptives) were evaluated for their effect on tear physiology. Subjects were 18 females taking oral contraceptives or their age matched controls (no medication), aged 21-33 years. Symptoms of ocular discomfort (visual analog scale), tear film structure (TearScope), non-invasive tear thinning time (HirCal grid), evaporation rate (ServoMed evaporimeter), osmolality (Nanolitre Osmometer), tear turnover rate, tear volume (Fluorotron Master), and tear protein levels (HPLC) were measured around day 2 (D2), actually day 1-4 and day 19 (D19) actually day 18-21 of the cycle. No significant differences were found for any tear parameters between D2 and D19 for either pill users or controls alone, or in the comparison of pill users with controls. No effect on tear physiology was found for serum hormone changes induced by oral contraceptive use or by normal cyclic variations in healthy young females.

Transcriptional regulation of the Hedgehog effector CI by the zinc-finger gene combgap

Members of the Hedgehog (HH) family of secreted signaling molecules specify cell fate during animal development by controlling the activity of members of the Gli family of zinc-finger transcription factors in responding cells. In Drosophila the Gli homolog, cubitus interruptus (CI), is expressed only in the anterior compartment where it represses targets such as the signaling molecule genes decapentaplegic (dpp) and wingless (wg). HH is expressed in the posterior and diffuses into the anterior where it antagonizes CI repression resulting in dpp and wg expression immediately anterior to the compartment border. Reducing CI levels results in misexpression of wg and dpp, while CI misexpression in the posterior disrupts differentiation. Thus, normal disc patterning requires high levels of CI in the anterior and the absence of CI in the posterior. Here we show that mutations in combgap (cg) result in deregulation of CI expression, which is now expressed at much lower levels and ubiquitously, i.e., also in the posterior. Consequently, cg mutants phenocopy ci loss-of-function mutants in the anterior and ci gain-of-function mutants in the posterior. cg encodes a putative DNA-binding protein that regulates both transcriptional activation and repression of the ci gene.

arrow encodes an LDL-receptor-related protein essential for Wingless signalling

The Wnt family of secreted molecules functions in cell-fate determination and morphogenesis during development in both vertebrates and invertebrates (reviewed in ref. 1). Drosophila Wingless is a founding member of this family, and many components of its signal transduction cascade have been identified, including the Frizzled class of receptor. But the mechanism by which the Wingless signal is received and transduced across the membrane is not completely understood. Here we describe a gene that is necessary for all Wingless signalling events in Drosophila. We show that arrow gene function is essential in cells receiving Wingless input and that it acts upstream of Dishevelled. arrow encodes a single-pass transmembrane protein, indicating that it may be part of a receptor complex with Frizzled class proteins. Arrow is a low-density lipoprotein (LDL)-receptor-related protein (LRP), strikingly homologous to murine and human LRP5 and LRP6. Thus, our data suggests a new and conserved function for this LRP subfamily in Wingless/Wnt signal reception.

The role of tear physiology in ocular surface temperature

PURPOSE

To determine whether the more rapid cooling of the tear film in dry eyes is related to other tear film parameters, a battery of tear physiology tests was performed on dry eye patients and control subjects.

METHODS

Tear evaporation rate was measured with a modified Servomed (vapour pressure) evaporimeter and ocular temperature with an NEC San-ei 6T62 Thermo Tracer in 9 patients diagnosed as having dry eye and in 13 healthy control subjects. Variability in temperature across the ocular surface was described by the temperature variation factor (TVF). Lipid layer structure and tear film stability were assessed with the Keeler Tearscope and tear osmolality was measured by freezing point depression nanolitre osmometry.

RESULTS

The data were explored by principal component analysis. The subjects with and without dry eye could be separated into two distinct groups entirely on the basis of their tear physiology. Dry eye patients exhibited higher tear evaporation rates, osmolalities and TVF, lower tear film stabilities and poorer-quality lipid layers than the control subjects. A significant linear relationship was found to exist between tear evaporation rate and TVF for all subjects (R2 = 0.242, p = 0.024).

CONCLUSIONS

Rapid cooling of the tear film in dry eyes appears to be related to the reduced stability of the tears and the increased rate of evaporation. The higher latent heat of vaporisation, associated with the increased evaporation in dry eyes, may account for the increased rate of cooling of the tear film in this condition.

Spatial location studies on the chemical composition of human tear ferns

Tear ferns are the patterns formed when tears are allowed to dry on a clean smooth surface. The patterns have been categorised according to confluence of pattern, with less confluent ferns indicative of tear film abnormalities. Little is known about the mechanism that gives rise to this phenomenon. Previous work has concentrated on correlation of alterations in tear film composition on the ferning phenomenon. The present study takes a new approach by analysing the locations of chemical elements in the fern to understand how the ferns form. By means of SEM coupled with EDXA, Na, K and Cl were detected within the fern. Sulphur, indicative of the presence of macromolecules such as mucins and proteins, was only found at the very periphery of the dry tear drop. The results suggest that macromolecules do not play a direct role in the formation of the ferns. A model is put forward to explain the observation whereby proteins and mucins are precipitated selectively by increasing salt concentration at the drop margin.

Salicylate inhibition of Acanthamoeba attachment to contact lenses: a model to reduce risk of infection

PURPOSE

Acanthamoeba attachment (adsorption) to hydrogel contact lenses is enhanced by Pseudomonas aeruginosa biofilm. The effect of sodium salicylate on Acanthamoeba attachment to biofilm-coated and uncoated hydrogel lenses was investigated.

DESIGN

Experimental study.

PARTICIPANTS AND CONTROLS

A minimum of 16 replicates were used for each test condition; a control condition using clean lenses without biofilm was included.

METHODS

Four groups of hydrogel contact lenses (etafilcon A) were pretreated with P. aeruginosa to form a biofilm. In addition, two more groups remained untreated. Quartered lenses of all six groups were then incubated in a suspension of A. castellanii trophozoites. Two batches of lenses had either 3 or 30 mM sodium salicylate added to the bacterial suspension (stage 1 intervention). Two other batches of lenses had salicylate added to the amoebal suspension (stage 2 intervention). One of the batches, which had a stage 1 intervention, had salicylate added at the second stage as well. The remaining batches received no salicylate exposure and included lenses with and without biofilm coating.

MAIN OUTCOME MEASURE

The outcome measure in this study was the number of Acanthamoeba trophozoites attached, per square centimeter, to the hydrogel surfaces.

RESULTS

Biofilm coating from P. aeruginosa gave a significantly increased attachment of A. castellanii trophozoites to the contact lens. When introduced at a first (biofilm) stage, second (trophozoite attachment) stage, or with intervention at both stages, 30 mM sodium salicylate reduced amoebal attachment to the hydrogel lens. When applied to both stages and when applied at stage 2 to the biofilm coated contact lenses, 3 mM sodium salicylate reduced amoebal attachment. The 3 mM concentration was not effective for the lower level of amoebae attachment to uncoated (nonbiofilm) lenses.

CONCLUSIONS

Sodium salicylate successfully reduced amoebal trophozoite attachment to hydrogel lenses. This was the result of one of the following possibilities or a combination thereof: inhibition of biofilm formation; a direct effect on the amoebae; an alteration in the biofilm-amoebal attachment and resulting modification of the hydrogel lens surface. The results of this study suggest the major action is at stage 2 (on amoebal attachment to lenses) and favors alteration of the biofilm-amoebal attachment mechanism. This study demonstrates salicylate's potential benefit as a component of contact lens care solutions, designed to reduce microbial attachment and the risk of infection.

Decoding vectorial information from a gradient: sequential roles of the receptors Frizzled and Notch in establishing planar polarity in the Drosophila eye

The Drosophila eye is composed of several hundred ommatidia that can exist in either of two chiral forms, depending on position: ommatidia in the dorsal half of the eye adopt one chiral form, whereas ommatidia in the ventral half adopt the other. Chirality appears to be specified by a polarizing signal with a high activity at the interface between the two halves (the ‘equator’), which declines in opposite directions towards the dorsal and ventral poles. Here, using genetic mosaics, we show that this polarizing signal is decoded by the sequential use of two receptor systems. The first depends on the seven-transmembrane receptor Frizzled (Fz) and distinguishes between the two members of the R3/R4 pair of presumptive photoreceptor cells, predisposing the cell that is located closer to the equator and having higher Fz activity towards the R3 photoreceptor fate and the cell further away towards the R4 fate. This bias is then amplified by subsequent interactions between the two cells mediated by the receptor Notch (N) and its ligand Delta (Dl), ensuring that the equatorial cell becomes the R3 photoreceptor while the polar cell becomes the R4 photoreceptor. As a consequence of this reciprocal cell fate decision, the R4 cell moves asymmetrically relative to the R3 cell, initiating the appropriate chiral pattern of the remaining cells of the ommatidium.

Dexamethasone inhibition of leucocyte adhesion to rat mesenteric postcapillary venules: role of intercellular adhesion molecule 1 and KC

BACKGROUND

A previous study showed that the glucocorticoid dexamethasone, at doses of 100 microg/kg and above, inhibited leucocyte adhesion to rat mesenteric postcapillary venules activated with interleukin 1beta (IL-1beta), as assessed by videomicroscopy.

AIMS

To identify whether the adhesion molecule, intercellular adhesion molecule 1 (ICAM-1), or the chemokine KC could be targeted by the steroid to mediate its antiadhesive effect.

METHODS

Rat mesenteries were treated with IL-1beta (20 ng intraperitoneally) and the extent of leucocyte adhesion measured at two and four hours using intravital microscopy. Rats were treated with dexamethasone, and passively immunised against ICAM-1 or KC. Endogenous expression of these two mediators was validated by immunohistochemistry, ELISA, and the injection of specific radiolabelled antibodies.

RESULTS

Dexamethasone greatly reduced IL-1beta induced leucocyte adhesion, endothelial expression of ICAM-1 in the postcapillary venule, and release of the mast cell derived chemokine KC. Injection of specific antibodies to the latter mediators was also extremely effective in downregulating (>80%) IL-1beta induced leucocyte adhesion.

CONCLUSIONS

Induction by IL-1beta of endogenous ICAM-1 and KC contributes to leucocyte adhesion to inflamed mesenteric vessels. Without excluding other possible mediators, these data clearly show that dexamethasone interferes with ICAM-1 expression and KC release from mast cells, resulting in suppression of leucocyte accumulation in the bowel wall, which is a prominent feature of several gastrointestinal pathologies.

Transducing the Dpp morphogen gradient in the wing of Drosophila: regulation of Dpp targets by brinker

Dpp, a TGFbeta, organizes pattern in the Drosophila wing by acting as a graded morphogen, activating different targets above distinct threshold concentrations. Like other TGFbetas, Dpp appears to induce transcription directly via activation of a SMAD, Mad. However, here we demonstrate that Dpp can also control gene expression indirectly by downregulating the expression of the brinker gene, which encodes a putative transcription factor that functions to repress Dpp targets. The medial-to-lateral Dpp gradient along the anterior-posterior axis is complemented by a lateral-to-medial gradient of Brinker, and the presence of these two opposing gradients may function to allow cells to detect small differences in Dpp concentration and respond by activating different target genes.

A LIM-homeodomain combinatorial code for motor-neuron pathway selection

Different classes of vertebrate motor neuron that innervate distinct muscle targets express unique combinations of LIM-homeodomain transcription factors, suggesting that a combinatorial code of LIM-homeodomain proteins may underlie the control of motor-neuron pathway selection. Studies of LIM-homeodomain genes in mouse, Drosophila melanogaster and Caenorhabditis elegans have revealed functions of these genes in neuronal survival, axon guidance, neurotransmitter expression and neuronal function, but, to our knowledge, none of these studies have addressed the issue of a functional code. Here we study two members of this gene family in Drosophila, namely lim3, the homologue of the vertebrate Lhx3 and Lhx4 genes, and islet, the homologue of the vertebrate Isl1 and Is12 genes. We show that Drosophila lim3 is expressed by a specific subset of islet-expressing motor neurons and that mutating or misexpressing lim3 switches motor-neuron projections predictably. Our results provide evidence that lim3 and islet constitute a combinatorial code that generates distinct motor-neuron identities.

The role of Pseudomonas aeruginosa biofilm in the attachment of Acanthamoeba to four types of hydrogel contact lens materials

PURPOSE

The effect of the previous coating of a contact lens surface with Pseudomonas biofilm on adsorption of Acanthamoeba onto four types of hydrogel materials was investigated.

METHODS

Hydrogel contact lens quarters from each of the four FDA groups of hydrogel materials were incubated for at least 12 h in a suspension of 10(7)/ml of Pseudomonas aeruginosa (ATCC 27853) to coat their surfaces with biofilm. After rinsing, the lenses were incubated for 90 min in 5 x 10(5)/ml of Acanthamoeba castellanii trophozoites. New, uncoated lens quarters were incubated in the Acanthamoeba suspension as controls. After rinsing, all adsorbed trophozoites on one surface of each lens quarter were counted by direct light microscopy. Adsorption was expressed as numbers of amoebae per square centimeter of lens surface, and nonparametric data analysis was performed.

RESULTS

Acanthamoeba adsorption to new, uncoated lenses was greater for ionic materials (groups 3 and 4) than for the nonionic materials (groups 1 and 2). Pseudomonas biofilm increased adsorption on all four lens types.

CONCLUSION

Pseudomonas biofilm enhanced adsorption of Acanthamoeba on all lens types studied, but the adsorption to nonionic materials was significantly less. This suggests that all lens wearers may be at increased risk for Acanthamoeba infection if lenses are previously contaminated with bacterial biofilm, but this risk may be reduced by the use of certain lens types (low water content, nonionic materials).

The roles of the homeobox genes aristaless and Distal-less in patterning the legs and wings of Drosophila

In the leg and wing imaginal discs of Drosophila, the expression domains of the homeobox genes aristaless (al) and Distal-less (Dll) are defined by the secreted signaling molecules Wingless (Wg) and Decapentaplegic (Dpp). Here, the roles played by al and Dll in patterning the legs and wings have been investigated through loss of function studies. In the developing leg, al is expressed at the presumptive tip and a molecularly defined null allele of al reveals that its only function in patterning the leg appears to be to direct the growth and differentiation of the structures at the tip. In contrast, Dll has previously been shown to be required for the development of all of the leg more distal than the coxa. Dll protein can be detected in a central domain in leg discs throughout most of larval development, and in mature discs this domain corresponds to the distal-most region of the leg, the tarsus and the distal tibia. Clonal analysis reveals that late in development these are the only regions in which Dll function is required. However, earlier in development Dll is required in more proximal regions of the leg suggesting it is expressed at high levels in these cells early in development but not later. This reveals a correlation between a temporal requirement for Dll and position along the proximodistal axis; how this may relate to the generation of the P/D axis is discussed. Dll is required in the distal regions of the leg for the expression of tarsal-specific genes including al and bric-a-brac. Dll mutant cells in the leg sort out from wild-type cells suggesting one function of Dll here is to control adhesive properties of cells. Dll is also required for the normal development of the wing, primarily for the differentiation of the wing margin.

The effects of cyclooxygenase 2 inhibitors on cartilage erosion and bone loss in a model of Mycobacterium tuberculosis-induced monoarticular arthritis in the rat

Selective cyclooxygenase 2 (COX 2) inhibitors NS-398 and nimesulide were investigated for their effects on patellar cartilage and bone content in a model of Mycobacterium tuberculosis (M.tb)-induced monoarticular arthritis in the rat. The protective/destructive properties of these nonsteroidal antiinflammatory drugs (NSAIDs) were compared with piroxicam, known to accelerate cartilage breakdown and reduce bone erosion in this model in comparison to untreated arthritic controls. Male CFHB Wistar rats were injected intraarticularly with heat killed M.tb into the left stifle joint, resulting in loss of patellar cartilage glycosaminoglycans (GAG), bone erosion and inflammation. The right stifle joint received saline. Animals were dosed daily, p.o., with NS-398 (1, 10 mg/kg), nimesulide (0.5, 5 mg/kg) or piroxicam (10 mg/kg). Four days after M.tb injection, patellar GAG content, bone weight and joint swelling were measured in drug-treated animals and untreated arthritic controls. Changes in the left joint were compared to the right. The expression and distribution of COX 2 protein was determined by immunocytochemistry in synovial tissue from arthritic controls over the time course. Focal accumulations of inflammatory cells were positively immunolabelled for COX 2 in the synovium from the left stifle joint of untreated arthritic animals, 6 h after injection of M.tb. Labeling of inflammatory cell infiltrates increased and was widespread in the synovium at 24 h. By day 4 fibroblasts were positively labelled for COX 2 in addition to polymorphonuclear and mononuclear leukocytes. Piroxicam and nimesulide at the higher dose significantly exacerbated M.tb-induced cartilage GAG loss while NS-398 was without effect. Both COX 2 inhibitors did not alter M.tb-induced patellar bone loss. In contrast, piroxicam significantly reduced bone loss. All COX inhibitors significantly reduced joint swelling. In conclusion, the selective inhibition of COX 2 may result in the amelioration of synovitis with a lowered risk of NSAID-induced cartilage damage in rheumatic disease.