Indigenous men's pathways to 'living the right kind of life and walking the right path' post incarceration in Canada: understanding the impacts of systemic oppression, and guidance for healing and (w)holistic sexual health.

Indigenous men around the world hold expertise over their own lives. Informed by this perspective, this study centres this experience to better understand what is needed to improve sexual health outcomes among a group of men with a history of incarceration. Semi-structured interviews were conducted with 10 Indigenous men with such a history. Through thematic analysis the study identified two major themes: 1) the impacts of systemic oppression; 2) the value of guidance in walking the right path. Men identified colonial trauma and the associated mental, physical, emotional and spiritual wounds stemming from systemic oppression as continuing to impact their wellbeing. Men also described the systems of support necessary to help guide them on their journeys through incarceration, rehabilitation and building strong and nurturing relationships. Findings from the study provide important guidance from Indigenous men for future more holistic sexual health intervention programming.

Feasibility, safety and effectiveness of a pilot 16-week home-based, impact exercise intervention in postmenopausal women with low bone mineral density.

The feasibility and efficacy of home-based, impact exercise are unclear. This pilot impact exercise intervention was feasible and safe, and improved bone health and physical function in postmenopausal women with low bone density. Appropriately designed randomised controlled trials are now required to determine whether such interventions can reduce fracture risk. INTRODUCTION: The feasibility and efficacy of impact exercise in postmenopausal women with low bone mineral density (BMD) are unclear. We aimed to determine adherence, safety and changes in BMD, bone microarchitecture and physical function following a pilot home-based, impact exercise intervention in postmenopausal women with low BMD. METHODS: Fifty community-dwelling postmenopausal women with BMD T-scores < - 1.0 participated in 16 weeks of home-based impact exercise progressively increasing to 50 multi-directional unilateral hops on each leg daily. Bone density and structure were assessed by lumbar spine and hip dual-energy X-ray absorptiometry (DXA), 3D modelling (3D-SHAPER) of hip DXA scans and distal tibial high-resolution peripheral quantitative computed tomography scans. Physical performance was assessed by repeated chair stand time and stair climb time. RESULTS: Forty-four women (mean ± SD age 64.5 ± 7.5 years) completed the intervention, with adherence of 85.3 ± 17.3%. Reasons for withdrawal were related soreness (n = 2), unrelated injury (n = 1) and loss of interest (n = 3). Femoral neck areal BMD increased by 1.13 ± 3.76% (p = 0.048). Trabecular volumetric BMD (vBMD) increased at the total hip (2.27 ± 7.03%; p = 0.038) and femoral neck increased (3.20 ± 5.39%; p < 0.001). Distal tibia total vBMD increased by 0.32 ± 0.88% (p = 0.032) and cortical cross-sectional area increased by 0.55 ± 1.54% (p = 0.034). Chair stand and stair climb time improved by 2.34 ± 1.88 s (p < 0.001) and 0.27 ± 0.49 s (p < 0.001), respectively. CONCLUSION: A 16-week home-based, impact exercise was feasible and may be effective in improving femoral neck areal BMD, total hip and distal tibial vBMD and physical function in postmenopausal women. Appropriately designed randomised controlled trials are now required to determine whether such interventions can reduce fracture risk in older populations.

Associations between physical activity and bone structure in older adults: does the use of self-reported versus objective assessments of physical activity influence the relationship?

Associations of current and previous physical activity (PA) with bone health are unclear. In postmenopausal women with low bone mineral density (BMD), current PA was positively associated with femoral neck BMD and microarchitecture. Past PA was positively associated with tibial microarchitecture. PA appears beneficial for bone health throughout the lifespan. INTRODUCTION: To compare associations of current and past self-reported bone-specific physical activity, and current accelerometer-determined physical activity (PA), with bone structure (bone mineral density [BMD] and microarchitecture) in postmenopausal women with osteopenia or osteoporosis. METHODS: Fifty community-dwelling postmenopausal women (mean age 64.4 ± 7.7) with hip or spine BMD T-score < - 1.0 SD were recruited for an exercise intervention. At baseline, current, past and total Bone-specific Physical Questionnaire (BPAQ) scores were self-reported, and percentages of sedentary, light and moderate to vigorous PA (MVPA) were objectively determined by accelerometer measurements. Bone structure was assessed by lumbar spine and hip dual-energy X-ray absorptiometry (DXA), 3D modelling algorithms (3D-SHAPER) of hip DXA scans and distal tibial high-resolution peripheral quantitative computed tomography (HR-pQCT) scans. RESULTS: Current BPAQ scores and MVPA were significantly positively associated with femoral neck areal BMD (ß = 0.315, p = 0.031 and ß = 0.311, p = 0.042, respectively) following multivariable adjustments. MVPA was also positively associated with femoral cortical surface BMD (ß = 0.333, p = 0.028) and mean cortical thickness (ß = 0.374, p = 0.013). Past and total BPAQ scores demonstrated positive associations with tibial trabecular number (ß = 0.391, p = 0.008 and ß = 0.381, p = 0.010, respectively), and negative associations with trabecular separation (ß = - 0.396, p = 0.006 and ß = - 0.380, p = 0.009, respectively) and distribution (ß = - 0.411, p = 0.004 and ß = - 0.396, p = 0.006, respectively). Current BPAQ score was positively associated with tibial cortical periosteal perimeter (ß = 0.278, p = 0.014). CONCLUSION: BPAQ scores were most consistently associated with tibial bone parameters in older women, with past PA having lasting benefits for trabecular microarchitecture, and current PA positively associated with cortical bone.

The relationship between objectively assessed physical activity and bone health in older adults differs by sex and is mediated by lean mass.

Relationships between objectively assessed free-living physical activity (PA) and changes in bone health over time are poorly understood in older adults. This study suggests these relationships are sex-specific and that body composition may influence the mechanical loading benefits of PA. INTRODUCTION: To investigate associations of objectively assessed PA and bone health in community-dwelling older adults. METHODS: This secondary analysis of a subset of the Tasmanian Older Adult Cohort study included participants with PA assessed utilising ActiGraph GT1M accelerometers over 7 days (N = 209 participants, 53% female; mean ± SD age 64.5 ± 7.2 years). Steps/day and PA intensity were estimated via established thresholds. Bone mineral content (BMC) was acquired at the total hip, lumbar spine, legs and whole body by DXA at baseline and approximately 2.2 years later. Relationships between PA and BMC were assessed by multivariable linear regression analyses adjusted for age, smoking status, height and total lean mass. RESULTS: Men with above-median total hip BMC completed significantly less steps per day, but there was no significant difference in PA intensity compared with those with below-median BMC. There were no significant differences in PA in women stratified by median BMC. In women, steps/day were positively associated with leg BMC (B = 0.178; P = 0.017), and sedentary behaviour was negatively associated with leg BMC (- 0.165; 0.016) at baseline. After adjustment for confounders including lean mass and height, higher sedentary behaviour at baseline was associated with declines in femoral neck BMC (- 0.286; 0.011) but also with increases in pelvic BMC (0.246; 0.030) in men and increases in total hip BMC (0.215; 0.032) in women, over 2.2 years. No other significant longitudinal associations were observed after adjustment for body composition. CONCLUSIONS: Associations of accelerometer-determined sedentary behaviour and PA with bone health in older adults differ by sex and anatomical site and are mediated by body composition.

Visualizations for genetic assignment analyses using the saddlepoint approximation method.

We propose a method for visualizing genetic assignment data by characterizing the distribution of genetic profiles for each candidate source population. This method enhances the assignment method of Rannala and Mountain (1997) by calculating appropriate graph positions for individuals for which some genetic data are missing. An individual with missing data is positioned in the distributions of genetic profiles for a population according to its estimated quantile based on its available data. The quantiles of the genetic profile distribution for each population are calculated by approximating the cumulative distribution function (CDF) using the saddlepoint method, and then inverting the CDF to get the quantile function. The saddlepoint method also provides a way to visualize assignment results calculated using the leave-one-out procedure. This new method offers an advance upon assignment software such as geneclass2, which provides no visualization method, and is biologically more interpretable than the bar charts provided by the software structure. We show results from simulated data and apply the methods to microsatellite genotype data from ship rats (Rattus rattus) captured on the Great Barrier Island archipelago, New Zealand. The visualization method makes it straightforward to detect features of population structure and to judge the discriminative power of the genetic data for assigning individuals to source populations.

Evaluation of a potassium removal filter on irradiated red cells stored in SAGM.

BACKGROUND AND OBJECTIVES: Irradiation of red cell concentrates RCCs) can lead to well-documented elevated extracellular potassium concentrations. Transfusion of these products has the potential, if given as a massive/rapid transfusion, to lead to transient hyperkalemia. A potassium absorption filter (PAF) has recently been developed and has been proven to effectively remove excess K(+) . However, data are lacking on the red cell quality parameters over storage after irradiation. METHODS: Thirty RCCs were pooled and split into 3 groups of 10. All RCCs were irradiated on day 14 and filtered on day 28 (group 1 control), day 15 (group 2) or day 17 (group 3). Pre-irradiation, pre- and post-filtration and day 28 samples were taken for each study. Standard red cell quality parameters were measured over storage at the above time points. RESULTS: Losses for haemoglobin, haematocrit and volume were minimal after filtration with all units containing >40 g Hgb unit(-1). Statistically, significant differences were observed for K(+) and Na(+) levels in groups filtered at either 24 or 72 h post-irradiation, and this was observed directly after filtration and remained by day 28. Filtration had no significant impact on any other parameters measured. CONCLUSIONS: PAF effectively removed supernatant potassium (93%) from all RCC units. Early removal of K(+) at either day 15 or 17 on RCCs subsequently stored to day 28 had no measurable effect on red cell quality, suggesting this may be a useful device to ensure further safety for at-risk immunocompromised patient groups requiring irradiated RCCs.

Factors influencing student nurse decisions to report poor practice witnessed while on placement.

BACKGROUND: While it is commonly accepted that nursing care is generally of a good standard, it would be naïve to think that this is always the case. Over recent years, concern about aspects of the quality of some nursing care has grown. In tandem with this, there is recognition that nurses do not always report poor practice. As future registrants, student nurses have a role to play in changing this culture. We know, however, relatively little about the factors that influence student decisions on whether or not to report. In the absence of a more nuanced understanding of this issue, we run the risk of assuming students will speak out simply because we say they should. OBJECTIVES: To explore influences on student decisions about whether or not to report poor clinical practice, which is a result of deliberate action and which is witnessed while on placement. METHODS: Qualitative interviews were conducted with thirteen pre-registration nursing students from the UK. Participants included both adult and mental health nurses with an age range from 20 to 47. Data were analysed to identify key themes. Category integrity and fit with data were confirmed by a team member following initial analysis. RESULTS: Four themes. The first of these, 'I had no choice' described the personal and ethical drivers which influenced students to report. 'Consequences for self' and 'Living with ambiguity' provide an account of why some students struggle to report, while 'Being prepared' summarised arguments both for and against reporting concerns. CONCLUSION: While there is a drive to promote openness in health care settings and an expectation that staff will raise concerns the reality is that the decision to do this can be very difficult. This is the case for some student nurses. Our results suggest ways in which educationalists might intervene to support students who witness poor practice to report.

Storage of apheresis platelet concentrates after manual replacement of >95% of plasma with PAS 5.

BACKGROUND AND OBJECTIVES: Recently, a glucose- and bicarbonate-containing additive solution termed PAS 5 demonstrated acceptable 7-day platelet storage after >95% plasma replacement with PAS on the day of collection (Day 0). In this study, we examined platelet storage in >95% PAS 5 after manual washing of Day 1 apheresis platelets in plasma collected using either the Amicus or Trima plateletpheresis devices. MATERIAL AND METHODS: Triple platelet donations in plasma were obtained from Amicus (n = 10) and Trima (n = 10) plateletpheresis devices and stored overnight before being centrifuged and manually processed into three units with the following storage media: 100% plasma, >95% PAS 5 or 65% PAS 5/35% plasma. Platelet units were sampled on Days 1, 5 and 7 of storage using a range of tests recommended by the UK guidelines. RESULTS: The majority of in vitro assay results for platelets in PAS 5 were similar to results in paired 100% plasma platelets (controls). The pH of PAS 5 stored platelet units was above the UK recommended guidelines of 7·4 by Day 5. PAS 5 platelets were no more activated than controls as evidenced by comparable soluble P-selectin levels and CD62p and CD42b expression. PAS 5 platelets also exhibited adhesion and aggregation profiles higher than (Day 1) or comparable to (Days 5 and 7) controls as measured by Impact R. CONCLUSION: The 7-day in vitro storage parameters investigated were comparable between >95% PAS 5 and 100% plasma platelets derived from both Amicus and Trima plateletpheresis devices, with the exception that lactose dehydrogenase release rate and pH were significantly higher in PAS 5 units.

Characteristics of prion-filtered red cells suspended in pathogen-inactivated plasma (MB treated or solvent-detergent treated) for neonatal exchange transfusion.

BACKGROUND AND OBJECTIVES: Neonates undergoing exchange transfusion require <5-day-old red cells suspended in plasma. This study assesses the effect of replacing the saline, adenine, glucose and mannitol (SAGM) of prion reduced (P-Capt) red cells with either methylene blue-treated plasma (MBTFFP) or OctaplasLG to reduce the risk of variant Creutzfelt-Jakob disease transmission. MATERIALS AND METHODS: Twenty leucoreduced red cell units in SAGM were prion reduced on day 1. The SAGM was replaced by MBTFFP (n=10) or OctaplasLG (n=10). The units were irradiated and stored at 4°C for 24 h. A further 20 units were stored for 5 days before being processed as above. Haemolysis (%), potassium, ATP, 2,3-DPG and plasma proteins were measured. RESULTS: Haemolysis remained low (≤0·16%). Following irradiation and storage, red cells in both types of plasma showed similar changes in potassium and ATP concentrations. The 2,3-DPG concentrations were well maintained although lower in red cells in OctaplasLG compared with those in MBTFFP (4·79 vs. 6·83 µmoles/g Hb on day 6). MBTFFP contained lower concentrations of fibrinogen, FV and FVIII. In OctaplasLG, alpha-2-antiplasmin was approximately 0·4 U/ml lower than in MBTFFP. After 24 h at 4°C, free protein S in OctaplasLG fell from 0·82 to 0·57 IU/ml. Other plasma proteins, in both types of plasma, were stable. CONCLUSIONS: Red cells in both types of plasma demonstrated similar storage characteristics. The plasma proteins, except protein S in OctaplasLG, were stable over 24 h at 4°C in both types of plasma, and low FVIII concentrations were noted in the MBTFFP (group O) units used.

Stored red-blood-cells inhibit platelet function under physiologic flow.

BACKGROUND AND OBJECTIVES: The DiaMed Impact R tests platelet function under close to physiological flow conditions. The machine is designed to use whole blood but by adding back compatible red cells, it can be used to study stored platelet concentrates. To date, red cells ≤14 days old have been used. In this study, the effect on the assay of using red cells stored for up to 60 days was examined. MATERIAL AND METHODS: This study looked at buffy coat-derived platelet concentrates on day 2 of storage along with various stored red-blood-cells (RBC). To determine whether the age of the RBC is a factor in supporting adhesion and aggregation, platelets were assayed with either RBC stored between 2 and 60 days or with separated 'young' and 'old' red cell populations obtained using a centrifugation method and confirmed by percoll gradient analysis. RESULTS: A statistically significant difference was observed between red-blood-cells stored for ≤20 days compared with those which have been stored for 21-60 days in respect of their ability to support platelet adhesion (SC) and aggregation (AS) (P<0·01). Separating red cells by centrifugation into top (young population) and bottom (old population) showed that the effect of storage was much greater than was any difference between young and old at the individual time-points e.g. 'young' red cells from stored units were poorer at supporting platelet adhesion and aggregation than 'young' red cells from fresh units. CONCLUSION: Results suggest that the red cells should be stored for less than 21 days when using this assay. This assay may also allow assessment of red cell functionality.

Cold storage of pooled, buffy-coat-derived, leucoreduced platelets in plasma.

BACKGROUND: This study was designed to determine which in vitro assays would be most useful for studying the effects of cold storage on platelet concentrates and to establish an in vivo model for platelet recovery and survival. STUDY DESIGN AND METHODS: Paired, plasma-suspended, leucoreduced, buffy-coat-derived platelet concentrates were stored either at 22 or 4 degrees C. Prior to storage and after 18 h, 5 days and 7 days, samples were taken and various assays were performed. On day 6, in vivo studies were carried out using a model system. Galactosylation of the platelets, prior to cold storage, was also tested. RESULTS: Hypotonic shock response, collagen-induced aggregation, RANTES and P-selectin binding site measurements demonstrated differences between platelets stored at 22 and 4 degrees C. The glycocalicin assay was able to demonstrate microvesicle formation at 4 degrees C. The in vivo model showed that there was at least a 50% decrease in recovery and survival when the platelets were stored in the cold. Galactosylation did not improve these results. CONCLUSIONS: Several assays, both in vitro and in vivo, were able to detect differences in platelet-storage characteristics and in vivo recovery and survival in a model system. Galactosylation did not correct these cold-induced changes.

Breath ethane peaks during a single haemodialysis session and is associated with time on dialysis.

There is growing evidence that oxidative stress is increased in haemodialysis patients and that dialysis per se is a contributory factor. The elevated oxidant stress, a result of increased production of reactive oxidant species (ROS), may be due to increased pro-inflammatory activity and reduced antioxidant mechanisms. ROS are transitory molecules and therefore surrogate markers of oxidant damage are required. Identification of potential causes of oxidative damage such as dialyser membranes or dialysate has been proposed and therefore assessment of oxidative damage during a single dialysis session would be of interest. We have used breath ethane, a widely accepted marker of oxidative stress, to investigate the cause and extent of the resulting oxidative damage during single dialysis sessions. Our study involved assessment of breath ethane levels during haemodialysis in an end-stage renal failure haemodialysis population (n = 24). Breath samples were collected using discrete sampling techniques and were subsequently analysed using laser spectroscopy. Each patient adopted the role of longitudinal control in this study and his or her breath ethane level was monitored regularly during the dialysis session. Significant breath ethane elevation was observed at the beginning (within the first 10 min) of each dialysis session. This paper provides an in-depth statistical analysis and clinical discussion of the recent findings. A regression analysis of the collected breath ethane data showed a trend towards increased ethane levels for patients on dialysis for a shorter duration of time (r = 0.656, R-Sq = 43.3%, p = 0.001). Multiple linear regression was undertaken to further assess these associations and revealed that peak ethane levels were significantly and independently associated with time period on dialysis (p < 0.000), vascular access (p = 0.013) and male sex (p = 0.005). However, whilst diabetes status had demonstrated a correlation with peak ethane levels (0.525, p = 0.008) this was not independent of vascular access status. This multivariate linear model was significantly associated with Ln peak ethane levels (S = 0.744, R-Sq = 80.8%). The observed rapid rise in oxidative stress during the first few minutes after commencement of dialysis gives new insight into the dynamics of the oxidative damage resulting from dialysis treatment.

Extended storage of platelets in SSP platelet additive solution.

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate the effects of extended storage of pooled random platelets in SSP+ additive solution (MacoPharma). MATERIALS AND METHODS: Eight buffy coat-derived, pooled, leucoreduced platelet concentrates were prepared in 75% SSP+, 25% plasma using Fresenius/NPBI Composelect thrombocyte polishing filter (TPF) systems. Platelet concentrates were stored for 19 days in polyolefin storage bags and samples for in vitro analysis were taken at various time-points during storage. RESULTS: Platelet yields were lower than seen routinely when platelets are prepared in 100% plasma. The in vitro quality of the platelets stored in SSP+ was maintained until day 9. Glucose was depleted by day 12 and this was accompanied by a rapid fall in pCO2, a rise in pO2 and a cessation of lactate production. ATP and bicarbonate concentrations fell, the platelets began to swell and the ability to swirl decreased. Soluble P-selectin, glycocalicin, and regulated on activation, normal, T-cell expressed, and secreted (RANTES) concentrations increased, as did P-selectin expression. Loss of platelets and an increase in lacate hydrogenase concentration indicated that lysis had occurred. However, the pH remained between 6.4 and 7.4. CONCLUSIONS: The results suggest that SSP+ could be used for platelet storage for up to 9 days. However, the preparation of platelets in the additive requires some optimization. In vivo studies are required to confirm these in vitro results.

Application of laser spectroscopy for measurement of exhaled ethane in patients with lung cancer.

There is increasing interest in ethane (C(2)H(6)) in exhaled breath as a non-invasive marker of oxidative stress (OS) and thereby a potential indicator of disease. However, the lack of real-time measurement techniques has limited progress in the field. Here we report on a novel Tunable Diode Laser Spectrometer (TDLS) applied to the analysis of exhaled ethane in patients with lung cancer. The patient group (n=52) comprised randomly selected patients presenting at a respiratory clinic. Of these, a sub-group (n=12) was subsequently diagnosed with lung cancer. An age-matched group (n=12) corresponding to the lung cancer group was taken from a larger control group of healthy adults (n=58). The concentration of ethane in a single exhaled breath sample collected from all subjects was later measured using the TDLS. This technique is capable of real-time analysis of samples with accuracy 0.1 parts per billion (ppb), over 10 times less than typical ambient levels in the northern hemisphere. After correcting for ambient background, ethane in the control group (26% smokers) ranged from 0 to 10.54 ppb (median of 1.9 ppb) while ethane in the lung cancer patients (42% smokers) ranged from 0 to 7.6 ppb (median of 0.7 ppb). Ethane among the non-lung cancer patients presenting for investigation of respiratory disease ranged from 0 to 25 ppb (median 1.45 ppb). We conclude that, while the TDLS proved effective for accurate and rapid sample analysis, there was no significant difference in exhaled ethane among any of the subject groups. Comments are made on the suitability of the technique for monitoring applications.

Factors influencing women's views on the acceptability and experience of being opportunistically screened for Chlamydia trachomatis in hospital settings.

A subsample of 681 women participating in a two-centred, three-setting larger (2817) prevalence study were approached and, with consent, administered a questionnaire by post or in person. The questionnaire asked about their views of opportunistic screening for Chlamydia trachomatis (CT). The study response rate was 71%. In all, 94% women reported screening should be offered and most, on a regular basis. About 91% thought men should be screened but only 47% thought they would attend. Most (89%) knew the term 'chlamydia' but fewer, (63%) knew they could catch CT more than once. This is one of the very few UK studies which has explored women's views towards the acceptability of CT screening. Results suggest the majority of women report that screening for the condition is acceptable but not all have in-depth knowledge of CT. If a screening programme is to be established more education regarding the condition is required.

Molecular analysis of two cytochrome P450 monooxygenase genes required for paxilline biosynthesis in Penicillium paxilli, and effects of paxilline intermediates on mammalian maxi-K ion channels.

The gene cluster required for paxilline biosynthesis in Penicillium paxilli contains two cytochrome P450 monooxygenase genes, paxP and paxQ. The primary sequences of both proteins are very similar to those of proposed cytochrome P450 monooxygenases from other filamentous fungi, and contain several conserved motifs, including that for a haem-binding site. Alignment of these sequences with mammalian and bacterial P450 enzymes of known 3-D structure predicts that there is also considerable conservation at the level of secondary structure. Deletion of paxP and paxQ results in mutant strains that accumulate paspaline and 13-desoxypaxilline, respectively. These results confirm that paxP and paxQ are essential for paxilline biosynthesis and that paspaline and 13-desoxypaxilline are the most likely substrates for the corresponding enzymes. Chemical complementation of paxilline biosynthesis in paxG (geranygeranyl diphosphate synthase) and paxP, but not paxQ, mutants by the external addition of 13-desoxypaxilline confirms that PaxG and PaxP precede PaxQ, and are functionally part of the same biosynthetic pathway. A pathway for the biosynthesis of paxilline is proposed on the basis of these and earlier results. Electrophysiological experiments demonstrated that 13-desoxypaxilline is a weak inhibitor of mammalian maxi-K channels (Ki=730 nM) compared to paxilline (Ki=30 nM), indicating that the C-13 OH group of paxilline is crucial for the biological activity of this tremorgenic mycotoxin. Paspaline is essentially inactive as a channel blocker, causing only slight inhibition at concentrations up to 1 microM.

Opposing effects of butyrate and bile acids on apoptosis of human colon adenoma cells: differential activation of PKC and MAP kinases.

Butyrate, produced in the colon by fermentation of dietary fibre, induces apoptosis in colon adenoma and cancer cell lines, which may contribute to protection against colorectal cancer. However, butyrate is present in the colon along with other dietary factors, including unconjugated bile acids, which are tumour promoters. We have shown previously that the proapoptotic effects of butyrate on AA/C1 human adenoma cells were reduced in the presence of bile acids. To determine the cellular basis of this interaction, we examined the effects of butyrate and the secondary bile acid ursodeoxycholic acid (UDCA) on signalling pathways known to regulate apoptosis using AA/C1 cells. Butyrate activated PKC-delta and p38 MAP (mitogen-activated protein) kinase, whereas UDCA activated PKC-alpha and p42/44 MAP kinase. Butyrate treatment also resulted in the caspase-3-mediated proteolysis of PKC-delta. Butyrate-induced apoptosis was reduced by inhibitors of PKC-delta (Rottlerin), p38 MAP kinase (SB202190) and caspase 3 (DEVD-fmk), whereas the proliferative/survival effects of UDCA were blocked by inhibitors of PKC-alpha (Gö6976) and MEK 1 (PD98059). The effects of butyrate and bile acids are therefore mediated by the differential activation of signalling pathways that are known to regulate apoptosis.

Molecular cloning and genetic analysis of an indole-diterpene gene cluster from Penicillium paxilli.

The indole-diterpene paxilline is a potent tremorgenic mammalian mycotoxin and a known inhibitor of maxi-K ion channels. The gene cluster responsible for paxilline biosynthesis in Penicillium paxilli was identified by mapping four large plasmid-induced chromosome deletions. The cluster is predicted to lie within a 50 kb region of chromosome Va and to contain 17 genes, including a geranylgeranyl pyrophosphate (GGPP) synthase (paxG), two FAD-dependent monooxygenases (paxM and N), two cytochrome P450 monooxygenases (paxP and Q), a dimethylallyltryptophan (DMAT) synthase (paxD) and two possible transcription factors (paxR and paxS), which contain a Zn(II)2Cys6 DNA-binding motif. Targeted replacement of paxG confirmed that it is essential for paxilline biosynthesis but dispensable for growth. The GGPP for primary metabolism is predicted to be provided by a second GGPP synthase (ggs1) that was cloned, sequenced and mapped to chromosome IV. Semi-quantitative reverse transcriptase-polymerase chain reaction analysis demonstrated that the expression of paxG, paxM and paxP in submerged liquid cultures of P. paxilli increased dramatically with the onset of paxilline biosynthesis. In contrast, the expression of beta-tubulin (tub2) and ggs1 was not induced. This is the first description of the molecular cloning and genetic analysis of an indole-diterpene gene cluster.

Rheology of dental waxes.

OBJECTIVES: The rheological properties of waxes are of considerable interest in dentistry, yet the only adopted method of characterizing them in this respect is arbitrary and uninterpretable. The intention was to identify a means of doing so in an objective fashion and to apply it to a variety of products to establish the scope of behavior. METHOD: The modified Stokes' falling ball method was used to determine the apparent viscosity of 11 waxes over 25-45 degrees C under a wide range of loads and, therefore, strain rates. RESULTS: The falling ball method was demonstrated to be applicable over at least 7 orders of magnitude in viscosity, 7 in terminal velocity, and 3 in load. Waxes were shown to be pseudoplastic, lacking any identifiable yield point and having marked departures from Newtonian behavior. The pseudoplasticity followed a power law, the exponent of which (the pseudoplasticity parameter) was temperature dependent in a complex manner, but which showed a definite relationship to the reduced temperature, referred to the liquidus temperature. A master curve could not be constructed because of this variation, but also because of discontinuities in the isothermal contours attributed to stress-melting of components of the wax mixture. Stress-melting may in part account for the pseudoplasticity. SIGNIFICANCE: A standardized viscosity number has been defined at 30 degrees C and under 10 N load as the common logarithm of the falling ball apparent viscosity in order to characterize the flow behavior of dental waxes with a single convenient number. The shear thinning exponent, the reciprocal of the pseudoplasticity parameter, provides a similarly convenient measure of the stress-sensitivity of the wax. Direct objective comparison of the rheology of dental waxes may now be made, facilitating selection by the user through appropriate labeling.