A small-molecule PI3Kα activator for cardioprotection and neuroregeneration

Harnessing the potential beneficial effects of kinase signalling through the generation of direct kinase activators remains an underexplored area of drug development1-5. This also applies to the PI3K signalling pathway, which has been extensively targeted by inhibitors for conditions with PI3K overactivation, such as cancer and immune dysregulation. Here we report the discovery of UCL-TRO-1938 (referred to as 1938 hereon), a small-molecule activator of the PI3Kα isoform, a crucial effector of growth factor signalling. 1938 allosterically activates PI3Kα through a distinct mechanism by enhancing multiple steps of the PI3Kα catalytic cycle and causes both local and global conformational changes in the PI3Kα structure. This compound is selective for PI3Kα over other PI3K isoforms and multiple protein and lipid kinases. It transiently activates PI3K signalling in all rodent and human cells tested, resulting in cellular responses such as proliferation and neurite outgrowth. In rodent models, acute treatment with 1938 provides cardioprotection from ischaemia-reperfusion injury and, after local administration, enhances nerve regeneration following nerve crush. This study identifies a chemical tool to directly probe the PI3Kα signalling pathway and a new approach to modulate PI3K activity, widening the therapeutic potential of targeting these enzymes through short-term activation for tissue protection and regeneration. Our findings illustrate the potential of activating kinases for therapeutic benefit, a currently largely untapped area of drug development.

An exploratory study of sunitinib plus paclitaxel as first-line treatment for patients with advanced breast cancer

Background: Sunitinib has shown single-agent activity in patients with previously treated metastatic breast cancer (MBC). We investigated the safety of the combination of sunitinib and paclitaxel in an exploratory study of patients with locally advanced or MBC.

Methods: Patients received oral sunitinib 25 mg/day (with escalation to 37.5 mg/day as tolerated) on a continuous daily dosing schedule and paclitaxel 90 mg/m² on days 1, 8, and 15 of each 28-day cycle. Study endpoints included safety (primary endpoint), pharmacokinetics, and antitumor activity.

Results: Twenty-two patients were enrolled. The most frequent adverse events (AEs) were fatigue/asthenia (77%), dysgeusia (68%), and diarrhea (64%). Grade 3 AEs included neutropenia (43%), fatigue/asthenia (27%), neuropathy (18%), and diarrhea (14%). No drug–drug interaction was observed on the basis of pharmacokinetic analysis. Of 18 patients with measurable disease at baseline, 7 (38.9%) achieved objective responses (including 2 complete and 5 partial responses). Clinical responses were observed in three of nine patients with triple-negative receptor status (estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor-2 negative).

Conclusions: These data indicate that sunitinib and paclitaxel in combination are well tolerated in patients with locally advanced or MBC. No drug–drug interaction was detected and there was preliminary evidence of antitumor activity.

Bidentate ligation of magnesium by 1,2-dimethoxyethane in the gas phase

The 1:1 Mg...1,2-dimethoxyethane (Mg-DXE) complexes are studied experimentally and theoretically. They are generated by a laser ablation source in a supersonic expansion. They are studied spectroscopically by resonance two-photon ionization. Density functional theory/Becke three-dimensional Lee, Yang, and Parr and ab initio calculations using the MOLPRO quantum chemistry package are performed to document their ground and excited states in a series of geometry ranging from monodentate to bidentate ligation of Mg by the O atoms of DXE. An absorption band is observed in the 27 800-30 500 cm(-1) range, which, thanks to the calculations, is attributed to the bidentate complex. The structure of the band is discussed in terms of the excitation of electronic states of the complex correlating adiabatically to the 3s3p (1)P and 3s4s (1)S states of Mg at large separation between Mg and DXE.

Silver dressings: more evidence is needed to support their widespread clinical use

Anecdotal and clinical evidence suggests that silver dressings have a role to play in controlling local wound infection, but there is very little high-quality evidence to inform their use. Well-designed trials are needed to fill this evidence gap.

Transition-state spectroscopy of the photoinduced Ca + CH3F reaction. 3. Reaction following the local excitation to Ca(4s3d 1D)

The Ca* + CH3F --> CaF* + CH3 reaction was studied both experimentally and theoretically. The reaction was photoinduced in Ca...CH3F complexes, which were illuminated by a tunable laser in the range 18 000-24 000 cm-1. The absorption band that leads to the reaction extends between 19 000 and 23 000 cm-1. It is formed of three broad overlapping structures corresponding to the excitation of different electronic states of the complex. The two structures of lowest energy were considered in detail. They are associated with two series of respectively 2 and 3 molecular states correlating to Ca(4s3d 1D) + CH3F at infinite separation between Ca and CH3F. The assignment of these structures to specific electronic transitions of the complex stemmed from theoretical calculations where the Ca...CH3F complex is described by a linear Ca-F-C backbone. 2D potential energy surfaces were calculated by associating a pseudopotential description of the [Ca2+] and [F7+] cores, a core polarization operator on calcium, an extensive Gaussian basis, and a treatment of the electronic problem at the CI-MRCI level. All the excited levels correlating to the 4s2 1S, 4s3d 1D, and 4s4p 1P levels of Ca in the Ca + CH3F channel were documented in a calculation that explored the rearrangement channels where either Ca + CH3F or CaF + CH3 are formed. Then, wavepacket calculations on the 2D-PES's allowed one to simulate the absorption spectrum of the complex, in an approximation where the various electronic states of the complex are not coupled together. The assignment above stemmed from this. The second outcome of the calculation was that whatever the excited level of the complex that is considered, the reaction has to proceed through energy barriers. The electronic excitation of the complex on the red side of the absorption band does not seem to deposit enough energy in the system to overcome these barriers (even the lowest one) or to stimulate tunneling reactions. An alternative reaction mechanism involving a transfer to triplet PES's is proposed.

Effect of treatment with sunitinib malate, a multitargeted tyrosine kinase inhibitor, on circulating plasma levels of VEGF, soluble VEGF receptors 2 and 3, and soluble KIT in patients with metastatic breast cancer

578

Background: Sunitinib malate (SU11248) is a multitargeted tyrosine kinase inhibitor with antitumor and antiangiogenic activity that specifically inhibits VEGFR, PDGFR, KIT, RET and FLT3. In a phase II trial of 64 patients with refractory, metastatic breast cancer, sunitinib treatment resulted in an ∼11% objective response rate (Miller et al, ASCO 2005). To characterize potential biomarkers of biological response to sunitinib, we analyzed plasma levels of a panel of soluble proteins from patients in this trial. Methods: Patients received sunitinib in 6-week cycles comprised of 50 mg/day for 4 weeks followed by 2 weeks off treatment. Pre-dose plasma samples from 62 patients were obtained on days 1, 14, and 28 of the first cycle and days 1 and 28 of subsequent cycles. Plasma levels of VEGF, soluble VEGF receptor 2 (sVEGFR-2), soluble KIT (sKIT), and a novel biomarker, sVEGFR-3, were measured via ELISA analysis. Results: Plasma levels of each protein were modulated in most patients during the course of treatment. At the end of the first cycle, VEGF levels were increased more than 3-fold relative to baseline in 73% of cases, while sVEGFR-2 levels decreased by at least 30% in 88% of cases, and by >20% in all but 4 cases. In addition, levels of sVEGFR-3 were decreased by >30% in 82% of cases during the first cycle. For each of these markers, levels tended to return to near-baseline after 2 weeks off treatment. Longitudinal decreases in sKIT were also observed; decreases >50% by the end of cycle 2 were correlated with treatment outcomes for time-to-progression (P < 0.001) and survival (P = 0.03). Further analysis of correlations with pharmacokinetic and clinical parameters is ongoing. Conclusions: Sunitinib therapy is associated with increases in plasma VEGF and decreases in soluble VEGFRs and KIT. This panel of circulating proteins may have utility as pharmacodynamic biomarkers of sunitinib activity in patients with metastatic breast cancer. sVEGFR-3 may be a novel biomarker of the biological activity of sunitinib, while sKIT may be correlated with clinical response. Analysis of these and other biomarkers in larger studies of sunitinib in breast cancer may be warranted.

[Table: see text]

Transition State Spectroscopy of the Photoinduced Ca + CH3F Reaction. 2. Experimental and Ab Initio Studies of the Free Ca···FCH3 Complex

The Ca* + CH3F --> CaF + CH3 reaction was photoinduced in 1:1 Ca...CH3F complexes formed in a supersonic expansion. The transition state of the reaction was explored by monitoring the electronically excited product, CaF, while scanning the laser that turns on the reaction. Moreover, the electronic structure of the Ca...FCH3 system was studied using ab initio methods by associating a pseudopotential description of the [Ca2+] and [F7+] cores, a core polarization operator on calcium, an extensive Gaussian basis and a treatment of the electronic problem at the CCSD(T) (ground state) and RSPT2 (excited states) level. In this contribution we present experimental results for the free complex and a comparison with the results of a previous experiment where the Ca...CH3F complexes are deposited at the surface of large argon clusters. The ab initio calculations allowed an interpretation of the experimental data in terms of two reaction mechanisms, one involving a partial charge transfer state, the other involving the excitation of the C-F stretch in the CH3F moiety prior to charge transfer.

The postprandial state does not impair endothelial function in women with type 2 diabetes irrespective of glycaemic control

AIMS/HYPOTHESIS

The postprandial state has been shown to be associated with endothelial dysfunction, a predictor of cardiovascular morbidity. In type 2 diabetes, postprandial metabolic excursions are prolonged and exaggerated, but less pronounced if glycaemic control is optimised. We investigated the impact of improved glycaemic control on endothelial function in the postprandial state.

METHODS

We studied 19 postmenopausal women with type 2 diabetes and ten non-diabetic subjects. Participants with diabetes were re-studied 3 months after intensive glucose regulation. We measured forearm blood flow by strain gauge plethysmography during rest, during acetylcholine infusion and post ischaemia in the fasting state, and again 3 hours after a mixed meal (660 kcal, 55% fat).

RESULTS

Endothelium-dependent vasodilation was impaired in the diabetic group (p<0.005) and improved following an HbA1c reduction of 0.96% (p<0.05 for high-dose acetylcholine infusion). Postprandial metabolic excursions were higher in the diabetic group (p<0.001, p<0.01 and p<0.05 for glucose, insulin and triglycerides respectively). Resting forearm blood flow increased in all groups after the meal (p<0.005). There was no difference in fasting and postprandial endothelium-dependent vasodilation before and after improved glucose regulation in either group.

CONCLUSIONS/INTERPRETATION

The postprandial state does not impair endothelial function in non-diabetic women and does not make pre-existing endothelial dysfunction worse in women with type 2 diabetes, irrespective of glycaemic control.

Translational regulation of the plant S-adenosylmethionine decarboxylase

It is becoming apparent that control of protein synthesis by metabolites is more common than previously thought. Much of that control is exerted at the level of initiation of mRNA translation, orchestrated by upstream open reading frames (uORFs) and RNA secondary structure. S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis and both mammalian and plant AdoMetDCs are translationally regulated by uORFs in response to polyamine levels by distinct mechanisms.

Sterile saline versus tap water: which is most effective?

As a staff nurse who has recently moved to work in a primary care setting, I am often confused by the views of colleagues who appear unsure as to which is the right solution (tap water or saline) to use when cleaning wounds, most of them chronic. Is there a definitive answer to this question?

Wound-bed preparation

The editor welcomes readers' questions and alternative answers to questions and letters.These should be sent to the Journal of Wound Care, Greater London House, Hampstead Road, London NW1 7EJ. Fax: +44 (0)20-7874 0386. Email: jwc@emap.com

'Universal' concepts

It is assumed that the concepts of moist wound healing and wound-bed preparation are universally accepted and practised. However, the reality is that they are too often ignored, says Mark Collier

Health risk assessment of dioxin emissions from municipal waste incinerators: the Neerlandquarter (Wilrijk, Belgium)

Two municipal waste incinerators in the vicinity of a residential area close to the city of Antwerp caused concern to local habitants. Risk assessment was performed combining chemical, toxicological measurements and model calculations. As the first step in risk assessment an inventory was made of historic emissions from both incinerators with emphasis on dioxins. The operational atmospheric transport and deposition model for priority substances (OPS) was used to calculate the deposition of dioxins in the vicinity of incinerators. The observed soil contamination pattern did not correspond to the calculated deposition pattern, indicating that other sources may contribute at least partly to the local PCDD/PCDF contamination of the area. Dioxin exposure of people in the Neerlandquarter as a function of the food consumption behavior was calculated using a mathematical model (VLIER-HUMAAN) combined with transfer factors. According to the results of these calculations, just residing in the impact area does not result in a meaningful risk. Only if locally produced food was consumed (milk, meat and vegetables), exposure in the Neerlandquarter was enhanced compared to the average dioxin exposure estimated for the Flemish population. Exposure in 1997 was below the exposure in 1980. As a consequence of different eating habits and lower bodyweight, children are subjected to significantly higher exposure than adults. Adverse health outcomes from dioxin exposure in the past cannot be excluded. There was no evidence for enhanced exposure to genotoxicants based on a comparison of chromosomal damage to blood cells of children from the study area to those from a control group.

Cytogenetic investigations on microwaves emitted by a 455.7 MHz car phone

The chromosome aberration or sister chromatid exchange frequency was determined in 455.7 MHz microwave-exposed human lymphocytes and in lymphocytes that were subsequently exposed to MMC or X-rays. The exposure was performed by placing the cells at 5 cm from the antenna of a car phone. In this way the specific absorption ratio was approximately 6.5 W/kg. The temperature and humidity was kept constant during the experiments. No statistically significant difference was found between microwave-exposed and unexposed control samples. When the microwave exposure was followed by exposure to MMC, some differences were found between the combined treatments and the MMC treatments alone. However, there was no consistency in the results. Combined treatments with X-rays did not provide any indication of a synergistic action between the RF fields and X-rays, either. Our data therefore do not support the hypothesis that RF fields act synergistically with chemical or physical mutagens.

Cytogenetic effects of 900 MHz (GSM) microwaves on human lymphocytes

The cytogenetic effects of 900 MHz radiofrequency fields were investigated with the chromosome aberration and sister chromatid exchange frequency methods. Three different modes of exposure (continuous, pseudo-random and dummy burst) were studied for different power outputs (0, 2, 8, 15, 25, 50 W). The specific absorption rates varied between 0 and 10 W/kg. We investigated the possible effects of the 900 MHz radiation alone as well as of combined exposure to the chemical or physical mutagens mitomycin C and X-rays. Overall, no indication was found of a mutagenic, and/or co-mutagenic/synergistic effect of this kind of nonionizing radiation.

Phase I dose-escalation and pharmacokinetic study of a novel folate analogue AG2034

The novel folate analogue AG2034, which was designed as an inhibitor of GARFT (glycinamide ribonucleotide formyltransferase), was evaluated in this phase I study under the auspices of The Cancer Research Campaign, UK. AG2034 blocks de novo purine synthesis through inhibition of GARFT. A total of 28 patients with histologically proven intractable cancers were enrolled. AG2034 was administered as a short intravenous infusion once every 3 weeks. 8 dose levels ranging from 1-11 mg/m(2)were evaluated with patients receiving up to 6 cycles. Dose-limiting toxicities in the form of mucositis, diarrhoea and vomiting were observed at doses of 6 mg/m(2)and above. Significant levels of thrombocytopenia, neutropenia and anaemia were also recorded. Other sporadic toxicities included fatigue and myalgia. The MTD with this schedule of AG2034 was 5 mg/m(2). Most side effects occurred more frequently with cumulative dosing. In keeping with this, pharmacokinetic analysis revealed evidence of drug accumulation. The AG2034 AUC(0-24)increased by a median of 184% (range 20-389%) from cycle 1 to 3 in all 10 patients examined. No objective antitumour responses were observed in the study.

Cytogenetic effects of 50 Hz magnetic fields of different magnetic flux densities

Cytogenetic investigations were performed in human peripheral blood lymphocytes following exposure to 50 Hz magnetic fields alone or in combination with the chemical mutagen mitomycin C or with X-rays. It was found that magnetic fields up to 2500 microT did not significantly influence the chromosome aberration and sister chromatid exchange frequency. Also, the combined treatments failed to indicate the presence of any synergistic, potentiating, or antagonistic effect between the ELF magnetic fields and the mutagens. However, there were two exceptions: Cells exposed to 504 microT magnetic fields before and during cultivation displayed a statistically significant decrease in sister chromatid exchange frequency. Also, when cells were cultivated in the presence of 88.4 microT magnetic fields following X-ray exposures there was a significant increase in chromosome aberration frequency compared to X-ray exposure alone.

Management of patients with fungating wounds

In the absence of much literature about fungating wounds, Mark Collier presents a thought-provoking case history and describes the principles underpinning the optimal care of patients with fungating (malignant) wounds.

Nurses' views about pain and trauma at dressing changes: results of a national survey

Research findings and professional concerns that patients still experience pain and tissue trauma at dressing changes led specialist nurses to develop a postal questionnaire to elicit the views of 1000 nurses with an interest in wound management. The questionnaire asked practitioners to identify the primary considerations underpinning their approach to pain and tissue trauma at dressing changes, the strategies they adopted, and the factors which determined their treatment choices. The higher than anticipated response rate (37%) illustrates the importance nurses attach to this aspect of practice. The practitioners' main considerations during dressing changes were the need to prevent trauma to the wound (47%) and to avoid causing the patient pain (34%). Significantly, 81% noticed that patients experienced most pain when dressing products were removed, highlighting the need to re-emphasise the principles of moist wound healing. A total of 225 respondents (60%) were aware of dressings specifically designed to prevent pain and trauma during dressing changes. Practitioners also had the freedom to use the product of choice all (61%) or most (36%) of the time. However, respondents also demonstrated confusion about the properties and availability of many dressings. Recommendations for practice include reviewing the number of dressings currently available, together with ongoing education and update on all wound management dressing products and related issues.

Pain and tissue trauma during dressing change

BACKGROUND

Preventing patient pain and tissue trauma to the wound and surrounding skin are key considerations for nurses at the time of dressing changes. Mark Collier and Helen Hollinworth present the preliminary findings from a recent survey among nurses with an interest in wound care on the selection of dressing types.

CONCLUSION

Education of student and post-registration nurses about the properties of dressing products, with an understanding of the potential detrimental effects as a result of pain and trauma, is needed to help promote quality wound care. Selecting appropriate dressings was reported as the main strategy nurses adopted to help prevent pain and trauma at the time of dressing change. Appropriate product selection can improve patients' quality of life and optimise wound healing potential.

Blanching and non-blanching hyperaemia

A review of terms and definitions involved in the identification of risk of pressure ulcer development

Brevet tx: anti-embolism stockings for prevention and treatment of DVT

This article highlights the incidence and aetiology of thrombi, in particular deep vein thrombosis (DVT) before discussing the clinical features, diagnostic techniques and management of patients with suspected or confirmed DVT. The prophylactic use of anti-embolism stockings is then reviewed, including relevant clinical evidence, with particular reference to one of the leading brands of stocking currently available, that of Brevert tx (Seton Scholl Healthcare). The action, features, benefits and application of this type of anti-embolic stocking are detailed.

Acceptable evidence?

During the past few years, I have gained the impression in discussions with colleagues about evidence-based practice that evidence will be deemed worthy to shape cost-effective clinical practice only if it has been derived from a randomised controlled trial (RCT). If this is so, we must consider definitions. A randomised controlled trial is one in which treatment is truly randomised by using a computer-generated list, or quasi-randomised by using a random number table (for example, assignment to treatment by medical record number)1. Evidence is defined as the data on which to establish truth or falsehood2.

Shear bond strength of immediately repaired light-cured composite resin restorations

The goal of this study was to examine the extent to which the state of the surface of newly placed restorations made of one of two commercial formulations of composite resin (Pertac-Hybrid and Z-100) affects the interfacial bond strength when such restorations are immediately repaired with the same resin. Three groups of specimens for each material were prepared: one group in which there was an air-inhibited film on the surface of the initial layer of the restoration, another in which that film was prevented from being formed, and a third in which that surface was abraded prior to placement of the repair layer. All specimens were stored for 6 weeks in water at 23 degrees C before being loaded to fracture in shear at a rate of 5 mm/min. The shear bond strength results were treated using the three-parameter Weibull equation and a clearly defined index of performance (I), which is a measure of both the magnitude and variability of the shear bond strength. It was found that, for two states of the surface of the initial layer, I for Pertac-Hybrid specimens is about the same as that for Z-100 specimens. For specimens made of either material, there was a demonstrable difference in I between specimens with or without an air-inhibited film on the initial layer, while abrading the surface of that layer severely degraded I.

Reviews

PRESSURE SORES.

Regeneration of peri-implant infrabony defects using PerioGlas: a pilot study in rabbits

PerioGlas is a silicate-based synthetic bone augmentation material that has been used to fill periodontal defects with bonding and integration to both soft tissue and bone. The purpose of this research was to determine the PerioGlas interface with titanium dental implants and bone. Seven live rabbits were used; however, one rabbit was euthanized at 3 days as a result of a tibial fracture through the implant placement site. Each rabbit received four 3.3 x 8 mm Imtec titanium plasma-sprayed dental implants, two in each proximal tibia. One implant in each rabbit was placed in the standard fashion. Two implants in each rabbit had a surgically created defect adjacent to one side of the coronal aspect of the implant. The defect was subsequently filled with PerioGlas. One implant in each rabbit had a surgically created defect that was not filled with PerioGlas. The rabbits were sacrificed at 1, 2, 3, 6, 12, and 24 weeks. Each specimen was prepared for histologic viewing, yielding a nondecalcified specimen demonstrating the interface of bone, implant, and PerioGlas. The results demonstrate peripheral formation of osteoid, followed by bone deposition within the defect from host (surgical margin) bone, toward the implant. The new osteoid and bone form around the PerioGlas particles. Newly formed trabeculae connect these areas of osteoid and new bone around the PerioGlas, interconnecting the PerioGlas particles. The new bone eventually reaches the implant, and osseointegration occurs with incorporation of the PerioGlas particles.

Cytogenetic effects of 935.2-MHz (GSM) microwaves alone and in combination with mitomycin C

This paper focuses on the genetic effects of microwaves from mobile communication frequencies (935.2 MHz) alone and in combination with a chemical DNA-damaging agent (mitomycin C). Three cytogenetic endpoints were investigated after in vitro exposure of human whole blood cells. These endpoints were the 'classical' chromosome aberration test, the sister chromatid exchange test and the alkaline comet assay. No direct cytogenetic effect was found. The combined exposure of the cells to the radiofrequency fields followed by their cultivation in the presence of mitomycin C revealed a very weak effect when compared to cells exposed to mitomycin C alone.

Intracellular activation of gelatinase A (72-kDa type IV collagenase) by normal fibroblasts

Normal fibroblasts cultured as monolayers secrete matrix metalloproteinases (MMP), including gelatinase A (72-kDa type IV collagenase) as inactive zymogens. Previously we found that normal fibroblasts cultured in a type I collagen lattice (dermal equivalent) secrete active gelatinase A. Here we show that the activation of progelatinase A occurs within the cell and that the activator copurifies with Golgi membranes. Cell extracts of fibroblasts cultured in collagen lattices contain active 62-kDa gelatinase A at least 4-6 h before active enzyme is detected in the culture medium. Pulse-chase experiments confirm these results. The activator is membrane-bound and localizes to the Golgi-enriched fraction. Highly purified plasma membranes from lattice cultures are unable to convert gelatinase A from the zymogen to its active form. The activator may be a metalloproteinase because EDTA prevents activation of exogenous proenzyme by membrane fractions. Membrane-type MMP1, the enzyme thought to be responsible for activation of gelatinase A on the plasma membrane of tumor cells, shows no significant change in either mRNA or protein levels during lattice culture. Intracellular levels of gelatinase A mRNA and protein increase during the culture period, and tissue inhibitor of metalloproteinases concentration does not change. Because of the greater availability of tissue inhibitor of metalloproteinases-free proenzyme as a substrate for the activator, it is possible that membrane-type MMP1 is the activating enzyme. In that case, malignant transformation may involve a change in the localization of the activator to the plasma membrane.

Know how. Kinetic therapy

It is normal practice for patients in intensive care units to be turned regularly--every two hours, or more, depending on their medical condition and at-risk status. Manual turning makes high demands on nursing time and can result in a high incidence of back injuries. The introduction of kinetic therapy as a means of keeping patients moving is proving beneficial in both intensive care and high-dependency care settings to patients and their carers. It is a therapy that can be initiated by both nursing and medical staff.

From the Journals

MEASURING TEMPERATURE IN WOUND HEALING

WATER VAPOUR TRANSMISSION RATES

DYNAMIC PULSATION THERAPY