The Anticoagulant Properties of a Modified Form of Protein S

Protein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.

In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.

These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.

A compartmentalized phosphoinositide signaling axis at cilia is regulated by INPP5E to maintain cilia and promote Sonic Hedgehog medulloblastoma

Sonic Hedgehog (SHH) signaling at primary cilia drives the proliferation and progression of a subset of medulloblastomas, the most common malignant paediatric brain tumor. Severe side effects associated with conventional treatments and resistance to targeted therapies has led to the need for new strategies. SHH signaling is dependent on primary cilia for signal transduction suggesting the potential for cilia destabilizing mechanisms as a therapeutic target. INPP5E is an inositol polyphosphate 5-phosphatase that hydrolyses PtdIns(4,5)P₂ and more potently, the phosphoinositide (PI) 3-kinase product PtdIns(3,4,5)P₃. INPP5E promotes SHH signaling during embryonic development via PtdIns(4,5)P₂ hydrolysis at cilia, that in turn regulates the cilia recruitment of the SHH suppressor GPR161. However, the role INPP5E plays in cancer is unknown and the contribution of PI3-kinase signaling to cilia function is little characterized. Here, we reveal INPP5E promotes SHH signaling in SHH medulloblastoma by negatively regulating a cilia-compartmentalized PI3-kinase signaling axis that maintains primary cilia on tumor cells. Conditional deletion of Inpp5e in a murine model of constitutively active Smoothened-driven medulloblastoma slowed tumor progression, suppressed cell proliferation, reduced SHH signaling and promoted tumor cell cilia loss. PtdIns(3,4,5)P₃, its effector pAKT and the target pGSK3β, which when non-phosphorylated promotes cilia assembly/stability, localized to tumor cell cilia. The number of PtdIns(3,4,5)P₃/pAKT/pGSK3β-positive cilia was increased in cultured Inpp5e-null tumor cells relative to controls. PI3-kinase inhibition or expression of wild-type, but not catalytically inactive HA-INPP5E partially rescued cilia loss in Inpp5e-null tumor cells in vitro. INPP5E mRNA and copy number were reduced in human SHH medulloblastoma compared to other molecular subtypes and consistent with the murine model, reduced INPP5E was associated with improved overall survival. Therefore our study identifies a compartmentalized PtdIns(3,4,5)P₃/AKT/GSK3β signaling axis at cilia in SHH-dependent medulloblastoma that is regulated by INPP5E to maintain tumor cell cilia, promote SHH signaling and thereby medulloblastoma progression.

Post-processing strategies in image scanning microscopy

Image scanning microscopy (ISM) coupled with pixel reassignment offers a resolution improvement of √2 over standard widefield imaging. By scanning point-wise across the specimen and capturing an image of the fluorescent signal generated at each scan position, additional information about specimen structure is recorded and the highest accessible spatial frequency is doubled. Pixel reassignment can be achieved optically in real time or computationally a posteriori and is frequently combined with the use of a physical or digital pinhole to reject out of focus light. Here, we simulate an ISM dataset using a test image and apply standard and non-standard processing methods to address problems typically encountered in computational pixel reassignment and pinholing. We demonstrate that the predicted improvement in resolution is achieved by applying standard pixel reassignment to a simulated dataset and explore the effect of realistic displacements between the reference and true excitation positions. By identifying the position of the detected fluorescence maximum using localisation software and centring the digital pinhole on this co-ordinate before scaling around translated excitation positions, we can recover signal that would otherwise be degraded by the use of a pinhole aligned to an inaccurate excitation reference. This strategy is demonstrated using experimental data from a multiphoton ISM instrument. Finally we investigate the effect that imaging through tissue has on the positions of excitation foci at depth and observe a global scaling with respect to the applied reference grid. Using simulated and experimental data we explore the impact of a globally scaled reference on the ISM image and, by pinholing around the detected maxima, recover the signal across the whole field of view.

Development of a graded index microlens based fiber optical trap and its characterization using principal component analysis

We demonstrate a miniaturized single beam fiber optical trapping probe based on a high numerical aperture graded index (GRIN) micro-objective lens. This enables optical trapping at a distance of 200μm from the probe tip. The fiber trapping probe is characterized experimentally using power spectral density analysis and an original approach based on principal component analysis for accurate particle tracking. Its use for biomedical microscopy is demonstrated through optically mediated immunological synapse formation.

A hybrid discrete-continuum mathematical model of pattern prediction in the developing retinal vasculature

Pathological angiogenesis has been extensively explored by the mathematical modelling community over the past few decades, specifically in the contexts of tumour-induced vascularisation and wound healing. However, there have been relatively few attempts to model angiogenesis associated with normal development, despite the availability of animal models with experimentally accessible and highly ordered vascular topologies: for example, growth and development of the vascular plexus layers in the murine retina. The current study aims to address this issue through the development of a hybrid discrete-continuum mathematical model of the developing retinal vasculature in neonatal mice that is closely coupled with an ongoing experimental programme. The model of the functional vasculature is informed by a range of morphological and molecular data obtained over a period of several days, from 6 days prior to birth to approximately 8 days after birth. The spatio-temporal formation of the superficial retinal vascular plexus (RVP) in wild-type mice occurs in a well-defined sequence. Prior to birth, astrocytes migrate from the optic nerve over the surface of the inner retina in response to a chemotactic gradient of PDGF-A, formed at an earlier stage by migrating retinal ganglion cells (RGCs). Astrocytes express a variety of chemotactic and haptotactic proteins, including VEGF and fibronectin (respectively), which subsequently induce endothelial cell sprouting and modulate growth of the RVP. The developing RVP is not an inert structure; however, the vascular bed adapts and remodels in response to a wide variety of metabolic and biomolecular stimuli. The main focus of this investigation is to understand how these interacting cellular, molecular, and metabolic cues regulate RVP growth and formation. In an earlier one-dimensional continuum model of astrocyte and endothelial migration, we showed that the measured frontal velocities of the two cell types could be accurately reproduced by means of a system of five coupled partial differential equations (Aubert et al. in Bull. Math. Biol. 73:2430-2451, 2011). However, this approach was unable to generate spatial information and structural detail for the entire retinal surface. Building upon this earlier work, a more realistic two-dimensional hybrid PDE-discrete model is derived here that tracks the migration of individual astrocytes and endothelial tip cells towards the outer retinal boundary. Blood perfusion is included throughout plexus development and the emergent retinal architectures adapt and remodel in response to various biological factors. The resulting in silico RVP structures are compared with whole-mounted retinal vasculatures at various stages of development, and the agreement is found to be excellent. Having successfully benchmarked the model against wild-type data, the effect of transgenic over-expression of various genes is predicted, based on the ocular-specific expression of VEGF-A during murine development. These results can be used to help inform future experimental investigations of signalling pathways in ocular conditions characterised by aberrant angiogenesis.

Dynamics of angiogenesis during murine retinal development: a coupled in vivo and in silico study

The manner in which the superficial retinal vascular plexus (RVP) develops in neonatal wild-type mice is relatively well documented and poses an interesting challenge to the mathematical modelling community. Prior to birth, astrocyte sprouting and proliferation begin around the edge of the optic nerve head, and subsequent astrocyte migration in response to a chemotactic gradient of platelet-derived growth factor (PDGF)-A results in the formation of a dense scaffold on the surface of the inner retina. Astrocytes express a variety of chemotactic and haptotactic proteins that subsequently induce endothelial cell sprouting and modulate growth of the RVP. An experimentally informed, two-dimensional hybrid partial differential equation-discrete model is derived to track the outward migration of individual astrocyte and endothelial tip cells in response to the appropriate biochemical cues. Blood perfusion is included throughout the development of the plexus, and the evolving retinal trees are allowed to adapt and remodel by means of several biological stimuli. The resulting wild-type in silico RVP structures are compared with corresponding experimental whole mounts taken at various stages of development, and agreement between the respective vascular morphologies is found to be excellent. Subsequent numerical predictions help elucidate some of the key biological processes underlying retinal development and demonstrate the potential of the virtual retina for the investigation of various vascular-related diseases of the eye.

Impact of a standard medication chart on prescribing errors: a before-and-after audit

OBJECTIVES

(1) To develop and implement a standard medication chart, for recording prescribing (medication orders) and administration of medication in public hospitals in Queensland. (2) To assess the chart's impact on the frequency and type of prescribing errors, adverse drug reaction (ADR) documentation and safety of warfarin prescribing. (3) To use the chart to facilitate safe medication management training.

DESIGN, SETTING AND PARTICIPANTS

The medication chart was developed through a process of incident analysis and work practice mapping by a multidisciplinary collaborative. Observational audits by nurse and pharmacist pairs, of all available prescriptions before and after introduction of the standard medication chart, were undertaken in five sites.

RESULTS

Similar numbers of both patients (730 pre-implementation and 751 post-implementation; orders, 9772 before and 10 352 after) were observed. The prescribing error rate decreased from 20.0% of orders per patient before to 15.8% after (Mann-Whitney U test, p = 0.03). Previous ADRs were not documented for 19.5% of 185 patients before and 11.2% of 197 patients after (chi(2), p = 0.032). Prescribing errors involving selection of a drug to which a patient had had a previous ADR decreased from 11.3% of patients before to 4.6% after (chi(2), p = 0.021). International normalised ratios (INRs) >5 decreased from 1.9% of 14 405 INRs in the 12 months before to 1.45% of 15 090 INRs after (chi(2), p = 0.004). After minor modifications, the chart was introduced into all hospitals statewide, which enabled standardised medication training and safer rotation of staff. The chart also formed the basis for the National Inpatient Medication Chart.

CONCLUSION

Introduction of a standard revised medication chart significantly reduced the frequency of prescribing errors, improved ADR documentation and decreased the potential risks associated with warfarin management. The standard chart has enabled uniform training in medicine management.

Post-liver transplantation multicentric Castleman disease treated with valganciclovir and weaning of immunosuppression

Multicentric Castleman disease is a lymphoproliferative disorder which when seen in the setting of HIV/AIDS is often associated with human herpes virus 8 (HHV-8) infection. We describe the case of a HIV-negative man who developed HHV-8-associated multicentric Castleman disease 11 years after liver transplantation. The patient presented with fevers and weight loss. Physical examination revealed enlarged cervical, axillary and inguinal lymph nodes. Widespread lymphadenopathy was confirmed on computed tomography (CT) scanning. Histology of an enlarged lymph node showed a polymorphous infiltrate with mature plasma cells, plasmacytoid lymphocytes and occasional blasts within the cortex and paracortex. The diagnosis of Castleman disease was confirmed by the finding of numerous HHV-8-immunopositive cells around the regressed lymph node follicles and the detection of HHV-8 on plasma PCR. Although the conventional treatment for this condition has been combination chemotherapy, in the post-transplant context it was decided to treat the patient with valganciclovir and cessation of immunosuppression. His symptoms resolved rapidly and repeat plasma PCR done 3 months after starting treatment was negative for HHV-8. A follow-up CT scan showed a dramatic reduction in the size and amount of lymphadenopathy. After 15 months of treatment, he remains well with no evidence of graft dysfunction or rejection.

Electron paramagnetic resonance in human fingernails: the sponge model implication

The most significant problem of electron paramagnetic resonance (EPR) fingernail dosimetry is the presence of two signals of non-radiation origin that overlap the radiation-induced signal (RIS), making it almost impossible to perform dose measurements below 5 Gy. Historically, these two non-radiation components were named mechanically induced signal (MIS) and background signal (BKS). In order to investigate them in detail, three different methods of MIS and BKS mutual isolation have been developed and implemented. After applying these methods, it is shown here that fingernail tissue, after cut, can be modeled as a deformed sponge, where the MIS and BKS are associated with the stress from elastic and plastic deformations, respectively. A sponge has a unique mechanism of mechanical stress absorption, which is necessary for fingernails in order to perform its everyday function of protecting the fingertips from hits and trauma. Like a sponge, fingernails are also known to be an effective water absorber. When a sponge is saturated with water, it tends to restore to its original shape, and when it loses water, it becomes deformed again. The same happens to fingernail tissue. It is proposed that the MIS and BKS signals of mechanical origin be named MIS1 and MIS2 for MISs 1 and 2, respectively. Our suggested interpretation of the mechanical deformation in fingernails gives also a way to distinguish between the MIS and RIS. The results obtained show that the MIS in irradiated fingernails can be almost completely eliminated without a significant change to the RIS by soaking the sample for 10 min in water. The proposed method to measure porosity (the fraction of void space in spongy material) of the fingernails gave values of 0.46-0.48 for three of the studied samples. Existing results of fingernail dosimetry have been obtained on mechanically stressed samples and are not related to the "real" in vivo dosimetric properties of fingernails. A preliminary study of these properties of pre-soaked (unstressed) fingernails has demonstrated their significant difference from fingernails stressed by cut. They show a higher stability signal, a less intensive non-radiation component, and a nonlinear dose dependence. The findings in this study set the stage for understanding fingernail EPR dosimetry and doing in vivo measurements in the future.

Q-band EPR biodosimetry in tooth enamel microsamples: feasibility test and comparison with x-band

A comparative study of electron paramagnetic resonance dosimetry in Q- and X-bands has shown that Q-band is able to provide accurate measurements of radiation doses even below 0.5 Gy with tooth enamel samples as small as 2 mg. The optimal amount of tooth enamel for dose measurements in Q-band was found to be 4 mg. This is less than 1% of the total amount of tooth enamel in one molar tooth. Such a small amount of tooth enamel can be harmlessly obtained in an emergency requiring after-the-fact radiation dose measurement. The other important advantage of Q-band is full resolution of the radiation-induced EPR signal from the native, background signal. This separation makes dose response measurements much easier in comparison to conventional X-band measurements in which these overlapping signals necessitate special methods for doses below 0.5 Gy. The main disadvantages of Q-band measurements are a higher level of noise and lower spectral reproducibility than in X-band. The effect of these negative factors on the precision of dose measurements in Q-band could probably be reduced by improvement of sample fixation in the resonance cavity and better optimization of signal filtration to reduce high-frequency noise.

Protocol for emergency EPR dosimetry in fingernails

There is an increased need for after-the-fact dosimetry because of the high risk of radiation exposures due to terrorism or accidents. In case of such an event, a method is needed to make measurements of dose in a large number of individuals rapidly and with sufficient accuracy to facilitate effective medical triage. Dosimetry based on EPR measurements of fingernails potentially could be an effective tool for this purpose. This paper presents the first operational protocols for EPR fingernail dosimetry, including guidelines for collection and storage of samples, parameters for EPR measurements, and the method of dose assessment. In a blinded test of this protocol application was carried out on nails freshly sampled and irradiated to 4 and 20 Gy; this protocol gave dose estimates with an error of less than 30%.

EPR dosimetry in chemically treated fingernails

By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this approach is the presence of artifacts due to mechanically induced EPR signals (MIS) caused by mechanical stress during the collection and preparation of the samples and the so-called background (non-radiation) signal (BKS). The MIS and BKS have spectral parameters (shape, g-factor and linewidth) that overlap with the radiation-induced signal (RIS) and therefore, if not taken into account properly, could result in a considerable overestimation of the dose. We have investigated the use of different treatments of fingernails with chemical reagents to reduce the MIS and BKS. The most promising chemical treatment (20 min with 0.1 M dithiothreitol aqueous solution) reduced the contribution of MIS and BKS to the total intensity of EPR signal of irradiated fingernails by a factor of 10. This makes it potentially feasible to measure doses as low as 1 Gy almost immediately after irradiation. However, the chemical treatment reduces the intensity of the RIS and modifies dose dependence. This can be compensated by use of an appropriate calibration curve for assessment of dose. On the basis of obtained results it appears feasible to develop a field-deployable protocol that could use EPR measurements of samples of fingernails to assist in the triage of individuals with potential exposure to clinically significant doses of radiation.

Phosphorus transport pathways to streams in tile-drained agricultural watersheds

Agriculture is a major nonpoint source of phosphorus (P) in the Midwest, but how surface runoff and tile drainage interact to affect temporal concentrations and fluxes of both dissolved and particulate P remains unclear. Our objective was to determine the dominant form of P in streams (dissolved or particulate) and identify the mode of transport of this P from fields to streams in tile-drained agricultural watersheds. We measured dissolved reactive P (DRP) and total P (TP) concentrations and loads in stream and tile water in the upper reaches of three watersheds in east-central Illinois (Embarras River, Lake Fork of the Kaskaskia River, and Big Ditch of the Sangamon River). For all 16 water year by watershed combinations examined, annual flow-weighted mean TP concentrations were >0.1 mg L(-1), and seven water year by watershed combinations exceeded 0.2 mg L(-1). Concentrations of DRP and particulate P (PP) increased with stream discharge; however, particulate P was the dominant form during overland runoff events, which greatly affected annual TP loads. Concentrations of DRP and PP in tiles increased with discharge, indicating tiles were a source of P to streams. Across watersheds, the greatest DRP concentrations (as high as 1.25 mg L(-1)) were associated with a precipitation event that followed widespread application of P fertilizer on frozen soils. Although eliminating this practice would reduce the potential for overland runoff of P, soil erosion and tile drainage would continue to be important transport pathways of P to streams in east-central Illinois.

Effect of composite shade, increment thickness and curing light on temperature rise during photocuring

OBJECTIVES

To examine the effect of composite shade, increment thickness and curing light characteristics on the temperature rise associated with composite photocuring.

METHODS

Four shades (C2, A4, B1 and B3), four sample thicknesses (2, 3, 4 and 5 mm) of a hybrid resin composite and two curing units, one with two modes of curing, were investigated. The composite samples were packed in polytetrafluoroethylene (PTFE) moulds and cured for 40 s. Samples cured with the ramp curing mode were irradiated for only 20 s. Temperature rises on the undersurface of the curing resin composite were measured using an infrared scanning system.

RESULTS

Shade C2 produced the highest maximum temperature of all shades (56.7 degrees C). Thinner samples produced greater temperature rises (2mm induced 60.9 degrees C, 5 mm induced 45.7 degrees C). Samples cured with Optilux 501 unit produced greater temperature rises (60.9 degrees C) than those cured with Dentsply unit (56.2 degrees C).

CONCLUSIONS

There was a quantifiable amount of heat generated during visible light curing of resin composite. The amount of heat generated was influenced by shade selected, thickness of material and characteristics of the light curing unit.

Engineering Properties and Performance of Dental Crowns

Dental crowns are used to replace damaged natural crowns of teeth and are fixed to prepared teeth with luting cements, which should provide an adhesive bond to the tooth structure giving reliable retention and minimal microleakage. Mechanical testing of crowns in vitro gives failure load distributions that are well described by Weibull models, comparing probabilities of survival and reliability. Fatigue testing of crowns is time consuming, but regression analysis to interpolate functions through data points quoting probability limits or applying Weibull analysis is achievable. A complementary approach is to conduct materials tests with appropriate interfacial geometries. Luting cements are used in thin layers of 40–150 um. Contraction during polymerization is restrained by adhesion to substrates, allowing little relaxation of stresses. Conventional and resin-modified glass ionomer cements create thin zones of interaction with dentine and fail cohesively. The chevron notch short rod technique has been used to measure fracture toughness and rank cements. A development of this method, using chevron notch short bar specimens, permitted fracture toughness to be determined for luting cement-dentine substrate interfaces. Representative fracture experiments need to be developed to apply mixed mode conditions. The basic challenge to predict long-term performance from short-term laboratory tests remains.

Optimization of reading conditions for flat panel displays

Task Group 18 (TG 18) of the American Association of Physicists in Medicine has developed guidelines for Assessment of Display Performance for Medical Imaging Systems. In this document, a method for determination of the maximum room lighting for displays is suggested. It is based on luminance measurements of a black target displayed on each display device at different room illuminance levels. Linear extrapolation of the above luminance measurements vs. room illuminance allows one to determine diffuse and specular reflection coefficients. TG 18 guidelines have established recommended maximum room lighting. It is based on the characterization of the display by its minimum and maximum luminance and the description of room by diffuse and specular coefficients. We carried out these luminance measurements for three selected displays to determine their optimum viewing conditions: one cathode ray tube and two flat panels. We found some problems with the application of the TG 18 guidelines to optimize viewing conditions for IBM T221 flat panels. Introduction of the requirement for minimum room illuminance allows a more accurate determination of the optimal viewing conditions (maximum and minimum room illuminance) for IBM flat panels. It also addresses the possible loss of contrast in medical images on flat panel displays because of the effect of nonlinearity in the dependence of luminance on room illuminance at low room lighting.

Thermographic investigation of contemporary resin-containing dental materials

OBJECTIVES

To measure the temperature rise induced during visible light curing of modern resin-containing dental materials and the effect of dentine sections in reducing this temperature rise.

METHODS

A variety of newly introduced resin-containing materials were investigated, including flowable, packable and conventional hybrid composites, as well as a compomer and a resin modified glass ionomer material. The resin was packed into polytetrafluoroethylene (PTFE) moulds and cured for 40s. Temperature rises on the undersurface of the curing resin were measured using the Thermovision 900 infra-red scanning system. In the second part of the study, extracted, caries free teeth were sectioned into dentine disks of three thicknesses (0.7, 1.4 and 1.9 mm). Composite samples were overlaid by the disks and the insulating effect of dentine measured.

RESULTS

The maximum temperature increases were: 43.1 degrees C (flowable composite), 32.8 degrees C (conventional composite), 32.8 degrees C (RMGI), 23.3 degrees C (compomer) and 22.4 degrees C (packable composite).

CONCLUSIONS

There was a quantifiable amount of heat generated in resin-containing material during light curing. Dentine sections were good thermal insulators that significantly reduced temperature rises associated with resin composite photocuring.

Thermal mismatch strains in sidewall functionalized carbon nanotube/polystyrene nanocomposites

We present an unusual temperature dependence of thermal strains in 4-(10-hydroxy)decyl benzoate (HDB) modified SWNTPS (SWNT-single wall carbon nanotube, PS-polystyrene) nanocomposites. The strain transfer from the matrix to nanotubes in these nanocomposites, inferred from the frequency change of the Raman active tangential modes of the nanotubes, is enhanced strongly below 300 K, whereas it is vanishingly small at higher temperatures. The increased strain transfer is suggestive of reinforcement of the HDB-SWNTPS nanocomposites at low temperatures. On the other hand, the pristine SWNTs couple weakly to the PS matrix over the entire temperature range of 4.5-410 K. We argue that the strain transfer in HDB-SWNTPS is determined by the thermomechanical properties of the interface region composed of polystyrene plasticized by the tethered alkanelike modifier.

Audit of consultant physicians' reply letters for referrals to clinics in a tertiary teaching hospital

BACKGROUND

Doctors referring patients to consultant physicians seek reply letters which both educate and assist in ongoing patient management. Highly desirable attributes in specialist letters include clearly stated and justified: (i) diagnostic formulations, (ii) management regimens, (iii) use of clinical investigations, (iv) prognostic statements, (v) contingency plans and (vi) follow-up arrangements.

AIM

To explicitly evaluate the quality of reply letters for new patients referred to clinics at a tertiary teaching hospital.

METHODS

Letters were sampled from outpatient clinics of 10 different medical specialties at Princess Alexandra Hospital in Brisbane, Australia. Reply letters for new patient referrals between 1 August 2000 and 31 October 2000 were retrieved, from which data were abstracted to calculate the proportion of letters satisfying prespecified quality attributes.

RESULTS

Of 297 new patient referrals, reply letters were retrieved for 204 (69%). Of these, 147 (72%) referrals were accompanied by a referral letter, mostly (113/147; 77%) from general practitioners. For 120 referrals involving diagnostic issues, 69 (56%) letters stated a diagnostic formulation. Of 114 letters recommending further clinical investigations, 61 (53%) described a rationale for such testing. In 125 cases where therapy was a key issue, 83 (66%) letters recommended changes to current treatment for which reasons were specified in 46 (55%) cases, and contingency plans provided in 13 (16%). Prognosis was mentioned in only 18 (9%) cases. Follow-up arrangements were detailed in 123 (60%) letters. Assessments of patient understanding and likely adherence to therapy were stated in less than 15% of -letters.

CONCLUSIONS

Opportunities exist for improving quality of consultant physicians' reply letters in terms of greater use of problem lists, contingency plans, prognostic statements and patient-centred assessments, as well as more frequent enunciation of consultants' reasoning behind requests for further tests and changes to current management. Use of structured letter templates may facilitate more consistent inclusion of key information to referring doctors.

Deciphering the science behind electrocoagulation to remove suspended clay particles from water

Electrocoagulation removes pollutant material from water by a combination of coagulant delivered from a sacrificial aluminium anode and hydrogen bubbles evolved at an inert cathode. Rates of clay particle flotation and settling were experimentally determined in a 7 L batch reactor over a range of currents (0.25-2.0 A) and pollutant loadings (0.1-1.7 g/L). Sedimentation and flotation are the dominant removal mechanism at low and high currents, respectively. This shift in separation mode can be explained by analysing the reactor in terms of a published dissolved air flotation model.

Fracture mechanics analysis of the dentine-luting cement interface

The objectives of this study were to determine the fracture toughness of adhesive interfaces between dentine and clinically relevant, thin layers of dental luting cements. Cements tested included a conventional glass-ionomer, F (Fuji 1), a resin-modified glass-ionomer, FP (Fuji Plus) and a compomer cement, D (DyractCem). Ten miniature short-bar chevron notch specimens were manufactured for each cement, each comprising a 40 microm thick chevron of lute, between two 1.5 mm thick blocks of bovine dentine, encased in resin composite. The interfacial K(IC) results (MN/m3/2) were median (range): F; 0.152 (0.14-0.16), FP; 0.306 (0.27-0.37), D; 0.351 (0.31-0.37). Non-parametric statistical analysis showed that the fracture toughness of F was significantly lower (p <0.05) than those of FP or D, and all were significantly lower than values for monolithic cement specimens. Scanning electron microscopy of the specimens suggested crack propagation along the interface. However, energy dispersive X-ray analysis indicated that failure was cohesive within the cement. It is concluded that the fracture toughness of luting cement was lowered by cement-dentine interactions.

Intracanopy lighting reduces electrical energy utilization by closed cowpea stands

The high planting densities needed to grow edible biomass in sustainable space life support systems will create problems for planophile crops that form closed, self-shading canopies. The use of traditional overhead-lighting configurations will reduce the penetration of photosynthetically active radiation (PAR) into such canopies and will result in substantial shading of understory leaves. Intracanopy lighting, an irradiation approach that allows plants to grow around fixed arrays of low-intensity lamps, reduces overall energy expenditure for crop production by improving light distribution and interception throughout the canopy. Comparing different fluorescent lamp geometries within vegetative canopies of cowpea (Vigna unguiculata L. Walp) revealed great plasticity of leaf orientation to maximize absorption of PAR from lamps arrayed at various nontraditional angles. Varying the amount of photosynthetic energy available within canopies creates considerable potential to manipulate canopy productivity. Increasing lamp number 38% within cowpea canopies raised stand productivity 45%, reflecting the highly efficient interception and absorption of intracanopy PAR. However, combined above/within-canopy lighting did not increase overall PAR interception and vegetative yield, and productivity did not improve relative to the same input wattage of intracanopy lighting alone. Optimization of intracanopy lighting for crops to be used in future space life support systems will substantially reduce power and energy burdens for food-crop production.

The SH2-containing inositol polyphosphate 5-phosphatase, SHIP-2, binds filamin and regulates submembraneous actin

SHIP-2 is a phosphoinositidylinositol 3,4,5 trisphosphate (PtdIns[3,4,5]P3) 5-phosphatase that contains an NH2-terminal SH2 domain, a central 5-phosphatase domain, and a COOH-terminal proline-rich domain. SHIP-2 negatively regulates insulin signaling. In unstimulated cells, SHIP-2 localized in a perinuclear cytosolic distribution and at the leading edge of the cell. Endogenous and recombinant SHIP-2 localized to membrane ruffles, which were mediated by the COOH-terminal proline-rich domain. To identify proteins that bind to the SHIP-2 proline-rich domain, yeast two-hybrid screening was performed, which isolated actin-binding protein filamin C. In addition, both filamin A and B specifically interacted with SHIP-2 in this assay. SHIP-2 coimmunoprecipitated with filamin from COS-7 cells, and association between these species did not change after epidermal growth factor stimulation. SHIP-2 colocalized with filamin at Z-lines and the sarcolemma in striated muscle sections and at membrane ruffles in COS-7 cells, although the membrane ruffling response was reduced in cells overexpressing SHIP-2. SHIP-2 membrane ruffle localization was dependent on filamin binding, as SHIP-2 was expressed exclusively in the cytosol of filamin-deficient cells. Recombinant SHIP-2 regulated PtdIns(3,4,5)P3 levels and submembraneous actin at membrane ruffles after growth factor stimulation, dependent on SHIP-2 catalytic activity. Collectively these studies demonstrate that filamin-dependent SHIP-2 localization critically regulates phosphatidylinositol 3 kinase signaling to the actin cytoskeleton.

Selective nucleation and discovery of organic polymorphs through epitaxy with single crystal substrates

Crystallization of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (1), previously found to produce six conformational polymorphs from solution, on single-crystal pimelic acid (PA) substrates results in selective and oriented growth of the metastable "YN" (yellow needle) polymorph on the (101)(PA) faces of the substrate. Though the freshly cleaved substrate crystals expose (101)(PA) and (111)(PA) faces, which are both decorated with [101](PA) ledges that could serve as nucleation sites, crystal growth of YN occurs on only (101)(PA). Goniometry measurements performed with an atomic force microscope reveal that the (001)(YN) plane contacts (101)(PA) with a crystal orientation [100](YN)//[010](PA) and [010](YN)//[101](PA). A geometric lattice analysis using a newly developed program dubbed GRACE (geometric real-space analysis of crystal epitaxy) indicates that this interfacial configuration arises from optimal two-dimensional epitaxy and that among the six polymorphs of 1, only the YN polymorph, in the observed orientation, achieves reasonable epitaxial match to (101)(PA). The geometric analysis also reveals that none of the polymorphs, including YN, can achieve comparable epitaxial match with (111)(PA), consistent with the absence of nucleation on this crystal face. In contrast, sublimation of 1 on cleaved succinic acid (SA) substrates, which expose large (010)(SA) faces decorated with steps along [101](SA), affords growth of several polymorphs, each with multiple orientations, as well as oriented crystals of a new metastable polymorph on the (010)(SA) surfaces. The lack of polymorphic selectivity on (010)(SA) can be explained by the geometric lattice analysis, which reveals low-grade epitaxial matches between (010)(SA) and several polymorphs of 1 but no inherent selectivity toward a single polymorph. These observations demonstrate the sensitivity of crystal nucleation to substrate surface structure, the potential of crystalline substrates for selective nucleation and discovery of polymorphs, and the utility of geometric lattice modeling for screening of substrate libraries for controlling polymorphism.

Intracanopy lighting of cowpea canopies in controlled environments

Traditional designs for plant-growth lighting in space life support systems irradiate tops of closed foliar canopies while canopy understories are light limited. "Intracanopy lighting," a technique whereby plants are allowed to grow up and around multiple layers of low-intensity lamps that irradiate interior portions of canopies, can potentially enhance productivity while reducing overall energy consumption. Intracanopy lighting of cowpea (Vigna unguiculata L. Walp) was optimized by varying stand densities and lining growth compartments with light-scattering or reflective films. Yield rates using intracanopy lighting were less than those obtained with traditional lighting strategies. However, yield efficiencies and energetic conversion efficiencies, parameters that put edible yield in terms of inedible biomass, energetic, spatial, and temporal penalties, indicate intracanopy lighting is more efficient in crop production. Single-leaf photosynthetic rates indicate all leaves participate in net carbon gain regardless of age and position within a canopy.

Effects of carbon dioxide level and plant density on cowpea canopy productivity for a bioregenerative life support system

Plant density and atmospheric carbon dioxide level were manipulated to optimize productivity of cowpea [Vigna unguiculata (L.) Walp] for future use in a space-deployed Controlled Ecological Life Support System. Cowpea breeding line IT87D-941-1 was grown at plant densities of 3.6, 7.2, 10.7, or 14.3 plants m-2 in a growth chamber maintained at 400 (control) or 1200 (elevated) micromoles CO2 mol-1. Both green leaves and dried seeds were harvested as edible yield. Crop productivity was measured by edible yield rate (EYR), harvest index (HI), yield efficiency rate (YER), energy efficiency, and net photosynthesis (Pn). Increasing plant density within a canopy tended to increase EYR, but decreased HI and YER. Elevated CO2 also increased EYR, but decreased HI and YER as well. However, when the energy penalty for crop production was taken into consideration, cowpea crops grown under elevated CO2 were more productive than those grown at control CO2. Pn averaged 15 micromoles CO2 m-2 s-1 for cowpeas grown at 400 micromoles CO2 mol-1. Low Pn at the beginning and end of the cropping cycle indicated waste of high irradiance lighting during those times.

Characterization of an adapter subunit to a phosphatidylinositol (3)P 3-phosphatase: identification of a myotubularin-related protein lacking catalytic activity

The D3-phosphoinositides act as second messengers by recruiting, and thereby activating, diverse signaling proteins. We have previously described the purification of a rat phosphatidylinositol 3-phosphate [PtdIns(3)P] 3-phosphatase, comprising a heterodimer of a 78-kDa adapter subunit in complex with a 65-kDa catalytic subunit. Here, we have cloned and characterized the cDNA encoding the human 3-phosphatase adapter subunit (3-PAP). Sequence alignment showed that 3-PAP shares significant sequence similarity with the protein and lipid 3-phosphatase myotubularin, and with several other members of the myotubularin gene family including SET-binding factor 1. However, unlike myotubularin, 3-PAP does not contain a consensus HCX(5)R catalytic motif. The 3-PAP sequence contains several motifs that predict interaction with proteins containing Src homology-2 (SH2) domains, phosphotyrosine-binding (PTB) domains, members of the 14-3-3 family, as well as proteins with SET domains. Northern blot analysis identified two transcripts (5.5 kb and 2.5 kb) with highest abundance in human liver, kidney, lung, and placenta. 3-PAP immunoprecipitates isolated from platelet cytosol hydrolyzed the D3-phosphate from PtdIns(3)P and PtdIns 3,4-bisphosphate [PtdIns(3,4)P(2)]. However, insect cell-expressed 3-PAP recombinant protein was catalytically inactive, confirming our prior prediction that this polypeptide represents an adapter subunit.

Interaction of calmodulin with the cytoplasmic domain of the platelet membrane glycoprotein Ib-IX-V complex

Engagement of platelet membrane glycoprotein (GP) Ib-IX-V by von Willebrand factor triggers Ca(++)-dependent activation of alphaIIbbeta3, resulting in (patho)physiological thrombus formation. It is demonstrated here that the cytoplasmic domain of GPIb-IX-V associates with cytosolic calmodulin. First, an anti-GPIbalpha antibody coimmunoprecipitated GPIb-IX and calmodulin from platelet lysates. Following platelet stimulation, calmodulin dissociated from GPIb-IX and, like the GPIb-IX-associated proteins 14-3-3zeta and p85, redistributed to the activated cytoskeleton. Second, a synthetic peptide based on the cytoplasmic sequence of GPIbbeta, R149-L167 (single-letter amino acid codes), affinity-isolated calmodulin from platelet cytosol in the presence of Ca(++) as confirmed by comigration with bovine calmodulin on sodium dodecyl sulfate-polyacrylamide gels, by sequence analysis, and by immunoreactivity with the use of an anticalmodulin antibody. The membrane-proximal GPIbbeta sequence was analogous to a previously reported calmodulin-binding sequence in the leukocyte adhesion receptor, L-selectin. In addition, the cytoplasmic sequence of GPV, K529-G544, was analogous to a calmodulin-binding IQ motif within the alpha1c subunit of L-type Ca(++) channels. Calmodulin coimmunoprecipitated with GPV from resting platelet lysates, but was dissociated in stimulated platelets. A GPV-related synthetic peptide also bound calmodulin and induced a Ca(++)-dependent shift on nondenaturing gels. Together, these results suggest separate regions of GPIb-IX-V can directly bind calmodulin, and this novel interaction potentially regulates aspects of GPIb-IX-V-dependent platelet activation. (Blood. 2001;98:681-687)

Surface roughness and wettability of enamel and dentine surfaces prepared with different dental burs

The aim of dental adhesive restorations is to produce a long lasting union between the restoration and the tooth structure. This bond depends on many variables including the geometry of the preparation and the type of bonding agent or luting cement. It is therefore suggested that the topography of the tooth surface may influence the wettability and the bonding quality of adhesive systems. This study measured the surface roughness and wettability of enamel and dentine after preparation with different dental burs. The mesial and distal surfaces of 15 extracted sound human premolar teeth were prepared with a tungsten carbide crown bur, a diamond bur and a tungsten carbide finishing bur and finished in enamel or dentin, respectively. The prepared surfaces were analysed with a surface profilometer and scanning electron microscopy (SEM). The contact angle of distilled water on each of the prepared surfaces was used as the measure of wettability. The differences in average surface roughness (Ra) were significant between the rotary instrument groups, as revealed by a two-way ANOVA test. No differences were detected between enamel and dentine surfaces prepared with the same type of dental bur. The smoothest surfaces were those completed with tungsten carbide finishing burs. The diamond bur preparations were intermediate in the roughness assessment and the tungsten carbide crown burs gave the roughest surfaces. There were no significant differences in the contact angle measurements for the various groups. It was concluded that the surface roughness of enamel and dentine prepared by different rotary instruments had no significant influence on the wettability of distilled water on these surfaces.

Nondestructive, in vitro quantification of crown margins

STATEMENT OF PROBLEM

It is important that artificial crowns fit the prepared tooth accurately, as marginal deficiencies are predisposed to plaque accumulation and lead to increased risk of periodontal disease. Various methods of evaluation for marginal fit are described in the literature, but most approaches are limited by destructive methods of assessment and/or small points of measurement.

PURPOSE

This study compared, in vitro, the marginal fit of 4 types of complete crowns on human premolar teeth with the use of nondestructive profilometry. This method determined whether fit was influenced by type of crown or surface morphology of the tooth, namely, grooved or ungrooved surfaces.

MATERIAL AND METHODS

Four groups of specimens were prepared for complete crowns: group BA, bonding alloy with chamfer finish line; group G, gold alloy with chamfer finish line; group PC, porcelain with a chamfer finish line; and group PS, porcelain with a shoulder finish line. Two profiles of grooved mesial and ungrooved distal surfaces of the teeth were performed: (1) teeth prepared for each type of crown and (2) teeth with crowns seated but not cemented. Marginal fit (absolute marginal discrepancy) from the finish line edge of the tooth preparations to crown edges (CE) and leading edges (LE) of crowns were measured.

RESULTS

A 2-way analysis of variance for crown type and tooth surface morphology revealed significant differences between crown types for all measurement parameters, except vertical LE. The effect of surface morphology was not significant, except for vertical LE (P<.05). For all parameters, except vertical LE, the ranking of marginal fit discrepancies from greatest to least was as follows: group PC, G, BA, and PS. For vertical LE distances, the ranking was PS, BA, G, and PC (P<.05).

CONCLUSION

Profilometry was used as a nondestructive, accurate method of evaluating the absolute marginal fit of different types of crowns. Marginal fits varied continuously around the circumference of each crown and made clinical assessment of fit accuracy subjective and arduous.

A comparative evaluation of dental luting cements by fracture toughness tests and fractography

In recent years there has been a shift from traditional methods of investigating dental materials to a fracture mechanics approach. Fracture toughness (KIC) is an intrinsic material property which can be considered to be a measure of a material's resistance to crack propagation. Glass-ionomer cements are biocompatible and bioactive dental restorative materials, but they suffer from poor fracture toughness and are extremely susceptible to dehydration. The main objective of this study was to evaluate the fracture toughness of three types of commercially available dental cements (polyacid-modified composite resin, resin-modified and conventional glass ionomer) using a short-rod chevron-notch test and to investigate and interpret the results by means of fractography using scanning electron microscopy. Ten specimens of each cement were fabricated according to manufacturers' instructions, coated in varnish, and stored at ambient laboratory humidity, 100 per cent relative humidity, or in water at 37 degrees C for 7 days prior to preparation for testing. Results indicated that significant differences existed between each group of materials and that the fracture toughness ranged from 0.27 to 0.72 MN/m3/2. It was concluded that the resin-modified glass-ionomer cement demonstrated the highest resistance to crack propagation. Fractographs clearly showed areas of stable and unstable crack growth along the fractured surfaces for the three materials examined.

p110beta and p110delta phosphatidylinositol 3-kinases up-regulate Fc(epsilon)RI-activated Ca2+ influx by enhancing inositol 1,4,5-trisphosphate production

Fc(epsilon)RI-induced Ca2+ signaling in mast cells is initiated by activation of cytosolic tyrosine kinases. Here, in vitro phospholipase assays establish that the phosphatidylinositol 3-kinase (PI 3-kinase) lipid product, phosphatidylinositol 3,4,5-triphosphate, further stimulates phospholipase Cgamma2 that has been activated by conformational changes associated with tyrosine phosphorylation or low pH. A microinjection approach is used to directly assess the consequences of inhibiting class IA PI 3-kinases on Ca2+ responses after Fc(epsilon)RI cross-linking in RBL-2H3 cells. Injection of antibodies to the p110beta or p110delta catalytic isoforms of PI 3-kinase, but not antibodies to p110alpha, lengthens the lag time to release of Ca2+ stores and blunts the sustained phase of the calcium response. Ca2+ responses are also inhibited in cells microinjected with recombinant inositol polyphosphate 5-phosphatase I, which degrades inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), or heparin, a competitive inhibitor of the Ins(1,4,5)P3 receptor. This indicates a requirement for Ins(1,4,5)P3 to initiate and sustain Ca2+ responses even when PI 3-kinase is fully active. Antigen-induced cell ruffling, a calcium-independent event, is blocked by injection of p110beta and p110delta antibodies, but not by injection of 5-phosphatase I, heparin, or anti-p110alpha antibodies. These results suggest that the p110beta and p110delta isoforms of PI 3-kinase support Fc(epsilon)RI-induced calcium signaling by modulating Ins(1,4,5)P3 production, not by directly regulating the Ca2+ influx channel.

Mammalian inositol polyphosphate 5-phosphatase II can compensate for the absence of all three yeast Sac1-like-domain-containing 5-phosphatases

Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] plays a complex role in generating intracellular signalling molecules, and also in regulating actin-binding proteins, vesicular trafficking and vacuolar fusion. Four inositol polyphosphate 5-phosphatases (hereafter called 5-phosphatases) have been identified in Saccharomyces cerevisiae: Inp51p, Inp52p, Inp53p and Inp54p. Each enzyme contains a 5-phosphatase domain which hydrolyses PtdIns(4,5)P(2), forming PtdIns4P, while Inp52p and Inp53p also express a polyphosphoinositide phosphatase domain within the Sac1-like domain. Disruption of any two yeast 5-phosphatases containing a Sac1-like domain results in abnormalities in actin polymerization, plasma membrane, vacuolar morphology and bud-site selection. Triple null mutant 5-phosphatase strains are non-viable. To investigate the role of PtdIns(4,5)P(2) in mediating the phenotype of double and triple 5-phosphatase null mutant yeast, we determined whether a mammalian PtdIns(4,5)P(2) 5-phosphatase, 5-phosphatase II, which lacks polyphosphoinositide phosphatase activity, could correct the phenotype of triple 5-phosphatase null mutant yeast and restore cellular PtdIns(4,5)P(2) levels to near basal values. Mammalian 5-phosphatase II expressed under an inducible promoter corrected the growth, cell wall, vacuolar and actin polymerization defects of the triple 5-phosphatase null mutant yeast strains. Cellular PtdIns(4,5)P(2) levels in various 5-phosphatase double null mutant strains demonstrated significant accumulation (4.5-, 3- and 2-fold for Deltainp51Deltainp53, Deltainp51Deltainp52 and Deltainp52Deltainp53 double null mutants respectively), which was corrected significantly following 5-phosphatase II expression. Collectively, these studies demonstrate the functional and cellular consequences of PtdIns(4,5)P(2) accumulation and the evolutionary conservation of function between mammalian and yeast PtdIns(4,5)P(2) 5-phosphatases.

The yeast inositol polyphosphate 5-phosphatase Inp54p localizes to the endoplasmic reticulum via a C-terminal hydrophobic anchoring tail: regulation of secretion from the endoplasmic reticulum

The budding yeast Saccharomyces cerevisiae has four inositol polyphosphate 5-phosphatase (5-phosphatase) genes, INP51, INP52, INP53, and INP54, all of which hydrolyze phosphatidylinositol (4,5)-bisphosphate. INP54 encodes a protein of 44 kDa which consists of a 5-phosphatase domain and a C-terminal leucine-rich tail, but lacks the N-terminal SacI domain and proline-rich region found in the other three yeast 5-phosphatases. We report that Inp54p belongs to the family of tail-anchored proteins and is localized to the endoplasmic reticulum via a C-terminal hydrophobic tail. The hydrophobic tail comprises the last 13 amino acids of the protein and is sufficient to target green fluorescent protein to the endoplasmic reticulum. Protease protection assays demonstrated that the N terminus of Inp54p is oriented toward the cytoplasm of the cell, with the C terminus of the protein also exposed to the cytosol. Null mutation of INP54 resulted in a 2-fold increase in secretion of a reporter protein, compared with wild-type yeast or cells deleted for any of the SacI domain-containing 5-phosphatases. We propose that Inp54p plays a role in regulating secretion, possibly by modulating the levels of phosphatidylinositol (4,5)-bisphosphate on the cytoplasmic surface of the endoplasmic reticulum membrane.

Development of a program to manage costly outliers

The advanced practice nurse group devised a method to identify clinical variables of the elderly patients with multisystem failure requiring complex nursing care referred to as outlier. Outliers in this program were defined as patients whose hospital charges were greater than $50,000 with a length of stay greater than the primary diagnostic related group designated. Once criteria were identified, nursing strategies were developed to monitor the elderly patient, implement interventions, and evaluate patient outcomes. The goals of this program were to identify who the outliers might be prior to becoming outliers and to manage their nursing care early in their hospital course, attempting to match resource requirements with resource availability.

Decreased SLIM1 expression and increased gelsolin expression in failing human hearts measured by high-density oligonucleotide arrays

BACKGROUND

Failing human hearts are characterized by altered cytoskeletal and myofibrillar organization, impaired signal transduction, abnormal protein turnover, and impaired energy metabolism. Thus, expression of multiple classes of genes is likely to be altered in human heart failure.

METHODS AND RESULTS

We used high-density oligonucleotide arrays to explore changes in expression of approximately 7000 genes in 2 nonfailing and 2 failing human hearts with diagnoses of end-stage ischemic and dilated cardiomyopathy, respectively. We report altered expression of (1) cytoskeletal and myofibrillar genes (striated muscle LIM protein-1 [SLIM1], myomesin, nonsarcomeric myosin regulatory light chain-2 [MLC(2)], and ss-actin); (2) genes responsible for degradation and disassembly of myocardial proteins (alpha(1)-antichymotrypsin, ubiquitin, and gelsolin); (3) genes involved in metabolism (ATP synthase alpha-subunit, succinate dehydrogenase flavoprotein [SDH Fp] subunit, aldose reductase, and TIM17 preprotein translocase); (4) genes responsible for protein synthesis (elongation factor-2 [EF-2], eukaryotic initiation factor-4AII, and transcription factor homologue-HBZ17); and (5) genes encoding stress proteins (alphaB-crystallin and mu-crystallin). In 5 additional failing hearts and 4 additional nonfailing controls, we then compared expression of proteins encoded by the differentially expressed genes, alphaB-crystallin, SLIM1, gelsolin, alpha(1)-antichymotrypsin, and ubiquitin. In each case, changes in protein expression were consistent with changes in transcript measured by microarray analysis. Gelsolin protein expression was also increased in cardiomyopathic hearts from tropomodulin-overexpressing (TOT) mice and rac1-expressing (racET) mice.

CONCLUSIONS

Altered expression of the genes identified in this study may contribute to development of the heart failure phenotype and/or represent compensatory mechanisms to sustain cardiac function in failing human hearts.

The yeast inositol polyphosphate 5-phosphatases inp52p and inp53p translocate to actin patches following hyperosmotic stress: mechanism for regulating phosphatidylinositol 4,5-bisphosphate at plasma membrane invaginations

The Saccharomyces cerevisiae inositol polyphosphate 5-phosphatases (Inp51p, Inp52p, and Inp53p) each contain an N-terminal Sac1 domain, followed by a 5-phosphatase domain and a C-terminal proline-rich domain. Disruption of any two of these 5-phosphatases results in abnormal vacuolar and plasma membrane morphology. We have cloned and characterized the Sac1-containing 5-phosphatases Inp52p and Inp53p. Purified recombinant Inp52p lacking the Sac1 domain hydrolyzed phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] and PtdIns(3, 5)P(2). Inp52p and Inp53p were expressed in yeast as N-terminal fusion proteins with green fluorescent protein (GFP). In resting cells recombinant GFP-tagged 5-phosphatases were expressed diffusely throughout the cell but were excluded from the nucleus. Following hyperosmotic stress the GFP-tagged 5-phosphatases rapidly and transiently associated with actin patches, independent of actin, in both the mother and daughter cells of budding yeast as demonstrated by colocalization with rhodamine phalloidin. Both the Sac1 domain and proline-rich domains were able to independently mediate translocation of Inp52p to actin patches, following hyperosmotic stress, while the Inp53p proline-rich domain alone was sufficient for stress-mediated localization. Overexpression of Inp52p or Inp53p, but not catalytically inactive Inp52p, which lacked PtdIns(4,5)P(2) 5-phosphatase activity, resulted in a dramatic reduction in the repolarization time of actin patches following hyperosmotic stress. We propose that the osmotic-stress-induced translocation of Inp52p and Inp53p results in the localized regulation of PtdIns(3,5)P(2) and PtdIns(4,5)P(2) at actin patches and associated plasma membrane invaginations. This may provide a mechanism for regulating actin polymerization and cell growth as an acute adaptive response to hyperosmotic stress.

The inositol polyphosphate 5-phosphatases and the apurinic/apyrimidinic base excision repair endonucleases share a common mechanism for catalysis

Inositol polyphosphate 5-phosphatases (5-phosphatase) hydrolyze the 5-position phosphate from the inositol ring of phosphatidylinositol-derived signaling molecules; however, the mechanism of catalysis is only partially characterized. These enzymes play critical roles in regulating cell growth, apoptosis, intracellular calcium oscillations, and post-synaptic vesicular trafficking. The UCLA fold recognition server (threader) predicted that the conserved 300-amino acid catalytic domain, common to all 5-phosphatases, adopts the fold of the apurinic/apyrimidinic (AP) base excision repair endonucleases. PSI-BLAST searches of GENPEPT, using the amino acid sequence of AP endonuclease exonuclease III, identified all members of the 5-phosphatase family with highly significant scores. A sequence alignment between exonuclease III and all known 5-phosphatases revealed six highly conserved motifs containing residues that corresponded to the catalytic residues in the AP endonucleases. Mutation of each of these residues to alanine in the mammalian 43-kDa, or yeast Inp52p 5-phosphatase, resulted in complete loss of enzyme activity. We predict the 5-phosphatase enzymes share a similar mechanism of catalysis to the AP endonucleases, consistent with other common functional similarities such as an absolute requirement for magnesium for activity. Based on this analysis, functional roles have been assigned to conserved residues in all 5-phosphatase enzymes.

Inositol (1,4,5)trisphosphate metabolism and enhanced calcium mobilization in airway smooth muscle of hyperresponsive rats

Airway hyperresponsiveness (AHR) is a phenotype of asthma and can be modeled by the inbred Fisher strain of rat, which is hyperresponsive in vivo relative to the Lewis strain. Enhanced airway smooth muscle (ASM) contractility and Ca(2+) mobilization are associated with the AHR observed in Fisher rats. In this study, we investigated whether the interstrain differences in Ca(2+) mobilization to serotonin (5HT) result from differences in inositol (1,4,5)trisphosphate (IP(3)) metabolism and/or IP(3) receptor (IP(3)R) sensitivity. Ca(2+) mobilization by 5HT in cultured ASM cells from both rat strains was phospholipase C (PLC) dependent. Inositol polyphosphate accumulation, and hence PLC activity, was similar in both rat strains, but a specific IP(3) transient was detectable only in Fisher myocytes in response to 5HT. These findings suggested that IP(3) degradation rather than production differed between the two strains. The Vmax and Michaelis constant (K(m)) of IP(3)-specific 5-phosphatase activity were higher in the particulate fraction of Lewis than in Fisher ASM cell homogenates and appeared to be related to a greater expression of two isoforms of 5-phosphatase (type I and type II) in Lewis cells as shown by Western blot analysis. The sensitivity of the IP(3)R to IP(3) was similar between Fisher and Lewis ASM cells, indicating that the interstrain intracellular Ca(2+) differences were unrelated to IP(3)R function. We propose that interstrain variations in 5-phosphatase activity and expression may give rise to the interstrain differences in IP(3)-mediated Ca(2+) release in ASM and may be a determinant of AHR.

Selection of materials for post cementation

Many types of cement are available for post cementation, each with advantages and disadvantages. For posts with adequate mechanical retention, zinc phosphate is a good choice for patients for whom fluoride release is not considered essential. Posts with compromised mechanical retention benefit from use of a resin-modified glass-ionomer cement, which also releases fluoride. Composite resin cements should be reserved for rare cases where mechanical retention is so compromised that use of a resin-modified glass-ionomer cement provides inadequate retention. Great care is required when using composite resin cements to ensure optimum performance and avoid the creation of difficult-to-remove excess cement. Clinicians should be aware that posts cemented with resin-modified glass ionomer or composite resin cements may be difficult or impossible to remove if access to the root canal system is subsequently required.

Prevalence of lower respiratory tract infections in hospitalized patients in the United Kingdom and Eire--results from the Second National Prevalence Survey

During 1993 and 1994, the Hospital Infection Society conducted its Second National Prevalence Survey of infections in patients in British hospitals. The prevalence rates for hospital-acquired (HA) and community-acquired (CA), lower respiratory tract infections (LRTIs) were 2.4% and 6.1%, respectively; this shows an increase over that reported in the First National Prevalence Study. The prevalence rate of HA infections for ventilated patients was 18.6%. The prevalence was greater in males, odds ratio (OR, 95% CI) for HA-LRTIs (1.4, 1.1-1.6) and CA-LRTIs (1.2, 1.1-1.3) than in females. In the case of both HA-LRTIs and CA-LRTIs, there was an increase in prevalence in patients with age >75 years, (HA-LRTIs 1.7, 1.3-2.2; CA-LRTIs 1.7, 1.0-2.7). Results of multivariable logistic regression analysis showed an increased risk of HA-LRTIs in patients who had a nasogastric tube (3.6, 2.3-3.6), were ventilated (2.3, 1.6-3.2), trauma patients (2.2, 1.5-3.0), chronic obstructive airway disease (COAD), (1.9, 1.5-2.3), a tracheostomy (1.9, 1.3-2.7), prior blood transfusion (1.5, 1.2-1.8), smokers (1.4, 1.1-1.6) or on systemic corticosteroid therapy (OR 1.3, 1.1-1.6). Community-acquired LRTIs were positively associated with cystic fibrosis (33.7, 19.1-59.3), HIV (9.8, 6.5-14.8), COAD (4.8, 3.8-4.8), systemic corticosteroid therapy (2.5, 2.2-2.8), tracheostomy (1.8, 1.1-2.9), males (1.2, 1.1-1.3) and smoking (1.2, 1.1-1.4).

Cloning and characterization of a 72-kDa inositol-polyphosphate 5-phosphatase localized to the Golgi network

The inositol-polyphosphate 5-phosphatase enzyme family removes the 5-position phosphate from both inositol phosphate and phosphoinositide signaling molecules. We have cloned and characterized a novel 5-phosphatase, which demonstrates a restricted substrate specificity and tissue expression. The 3.9-kb cDNA predicts for a 72-kDa protein with an N-terminal proline rich domain, a central 5-phosphatase domain, and a C-terminal CAAX motif. The 3. 9-kilobase mRNA showed a restricted expression but was abundant in testis and brain. Antibodies against the sequence detected a 72-kDa protein in the testis in the detergent-insoluble fraction. Indirect immunofluorescence of the Tera-1 cell line using anti-peptide antibodies to the 72-kDa 5-phosphatase demonstrated that the enzyme is predominantly located to the Golgi. Expression of green fluorescent protein-tagged 72-kDa 5-phosphatase in COS-7 cells revealed that the enzyme localized predominantly to the Golgi, mediated by the N-terminal proline-rich domain, but not the C-terminal CAAX motif. In vitro, the protein inserted into microsomal membranes on the cytoplasmic face of the membrane. Immunoprecipitated recombinant 72-kDa 5-phosphatase hydrolyzed phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol 3, 5-bisphosphate, forming phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3-phosphate, respectively. We propose that the novel 5-phosphatase hydrolyzes phosphatidylinositol 3,4, 5-trisphosphate and phosphatidylinositol 3,5-bisphosphate on the cytoplasmic Golgi membrane and thereby may regulate Golgi-vesicular trafficking.

Phosphoinositide 3-kinase forms a complex with platelet membrane glycoprotein Ib-IX-V complex and 14-3-3zeta

The binding of von Willebrand factor (vWF) to glycoprotein (GP) Ib-IX-V stimulates transmembrane signaling events that lead to platelet adhesion and aggregation. Recent studies have revealed that the signaling protein 14-3-3 zeta binds directly to the cytoplasmic domain of GP Ib alpha. In this study, the dynamic association of 14-3-3 zeta with GP Ib-IX, the phosphoinositide 3-kinase (PI 3-kinase), or both, was investigated in resting, thrombin, or vWF and botrocetin-stimulated platelets by analysis of discrete subcellular fractions. Results of this study demonstrate maximal coimmunoprecipitation of 14-3-3 zeta with GP Ib-IX in the nonstimulated cytosolic fraction and in the actin cytoskeletal fraction of thrombin- or vWF-stimulated human platelets. Immunoprecipitated 14-3-3 zeta or GP Ib from cytosolic fractions contained PI 3-kinase enzyme activity and an 85-kd polypeptide recognized by antibodies to the p85 subunit of PI 3-kinase. After platelet activation, the level of association between these species decreased in the cytosolic fraction. However, increased complex formation between 14-3-3 zeta and GP Ib-IX and between PI 3-kinase and GP Ib-IX was detected in actin cytoskeletal fractions derived from thrombin- or vWF-stimulated platelets. Recombinant glutathione S-transferase-14-3-3 zeta fusion protein (14-3-3 zeta-GST) inhibited affinity-captured PI 3-kinase enzyme activity up to 70% at 2 mcmol/L 14-3-3 zeta-GST. However, increasing concentrations up to 5 mcmol/L 14-3-3 zeta-GST resulted in the 3-fold enhancement of PI 3-kinase enzyme activity. We propose that the association between PI 3-kinase and 14-3-3 zeta with GP Ib-IX serves to promote the rapid translocation of these signaling proteins to the activated cytoskeleton, thereby regulating the formation of 3-position phosphoinositide-signaling molecules in this subcellular compartment. (Blood. 2000;96:577-584)

Sustained elevation in inositol 1,4,5-trisphosphate results in inhibition of phosphatidylinositol transfer protein activity and chronic depletion of the agonist-sensitive phosphoinositide pool

The 43 kDa inositol polyphosphate 5-phosphatase (5-phosphatase) hydrolyses the signalling molecules inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4, 5)P(4)) in a signal-terminating reaction. We have utilised cell lines that stably underexpress the 43 kDa 5-phosphatase, as a model system to investigate whether Ins(1,4,5)P(3) can control the rate of its own formation by regulating the resupply of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)). A sustained 2.6-fold elevation in the basal concentration of Ins(1,4,5)P(3), in cell lines underexpressing the 43 kDa 5-phosphatase, correlated with a 32% reduction in the total cellular mass of PtdIns(4,5)P(2). The depletion in cellular PtdIns(4,5)P(2) was confined to a Triton-insoluble cell compartment, enriched in caveolin. In resting cells with elevated Ins(1,4,5)P(3) concentrations resulting from underexpression of the 43 kDa 5-phosphatase, phosphatidylinositol (PtdIns) and phosphatidylinositol 4-phosphate (PtdIns(4)P) were depleted by 50% and PtdIns(4,5)P(2) by 61% in the caveolin-enriched Triton-insoluble compartment. Agonist stimulation resulted in the rapid turnover of phosphoinositides in the caveolin-enriched Triton-insoluble fraction of vector-transfected cells, but not in cells with high basal Ins(1,4,5)P(3) concentrations. Depletion of phosphoinositides from the caveolin-enriched Triton-insoluble pool in cells underexpressing the 43 kDa 5-phosphatase did not result from activation of phospholipase C isoenzymes, or inhibition of PtdIns 4-kinase or PtdIns(4)P 5-kinase activities. Significant inhibition of phosphatidylinositol transfer protein (PITP) activity (up to 70%) was observed in cells with elevated basal Ins(1,4,5)P(3) concentrations; however, no reduction in PITP(α) protein expression was detected. These studies indicate that chronic elevation in cellular Ins(1,4,5)P(3) concentrations decreases the PITP-mediated resupply of phosphoinositides in the caveolin-enriched agonist-sensitive pool.