Possible involvement of a calcium-stimulated ATP-hydrolyzing activity associated with mycobacteriophage I3 in the DNA injection process.

Ca2+ ions are necessary for the successful propagation of mycobacteriophage I3. An assay for the phage DNA release in the presence of an isolated cell wall preparation from the host was established, and in this system Ca2+ ions also stimulated the release of DNA. The inhibition of phage DNA injection caused by Tween 80 (polyoxyethylene sorbitan monooleate), a nonionic detergent routinely used in mycobacterial cultures, was reversed by Ca2+. The presence of a phage-associated ATP-hydrolyzing activity was demonstrated. This enzyme was stimulated by Ca2+ ions and inhibited by Tween 80. From this and the behavior of the two agents at the level of DNA injection, as well as the fact that phage I3 has a contractile tail structure, we conclude that the phage-associated ATPase is involved in the DNA injection process.

Studies on follicular atresia: role of tropic hormone and steroids in regulating cathepsin-D activity of preantral follicles of the immature rat

The ovary of the immature female rat is comprised of primary and medium-sized preantral follicles. Upon stimulation with FSH or PMSG, the cathepsin-D activity, a representative lysosomal enzyme of granulosa cells, is reduced by 50% (P < 0.01). 17β-Estradiol at the doses tried was unable to mimic this effect. Blockade of steroidogenesis with cyanoketone also had no effect on the cathepsin-D activity of isolated granulosa cells. Dihydrotestosterone (DHT), however, at a dose of 1 mg/rat was able to inhibit PMSG's tropic action. It brought about an increase in cathepsin-D activity and reduction in steroidogenic activity of isolated granulosa cells. The atretogenic activity of DHT could be relieved by supplementation with exogenous FSH. DHT was observed to significantly reduce (P < 0.01) endogenous FSH and LH levels within 12–18 h of its injection suggesting that its atretic effect was due to its action at the pituitary rather than the gonad. In addition to the above the ability of 15 IU of PMSG to reduce cathepsin-D activity of granulosa cells was also significantly reduced (P < 0.01) if endogenous FSH was neutralized by a specific FSH antiserum. The present study suggests that as far as small and medium-sized primary and preantral follicles are concerned, FSH lack is the essential signal for onset of atresia.

Fluorescent alamethicin fragments A study of membrane activity and aqueous phase aggregation

The linear polypeptide antibiotic alamethicin is known to form channels in artificial lipid membranes. Synthetic 13- and 17-residue alamethicin fragments, labelled with a fluorescent dansyl group at the N-terminus, have been shown to translocate divalent cations across phospholipid membranes and to uncouple oxidative phosphorylation in rat liver mitochondria, in a manner analogous to the parent peptides. From studies of the aqueous phase aggregation behavior of the peptides, as well as their interaction with rat liver mitochondria, it is concluded that the interaction of the peptides with membranes is a complex process, probably involving both aqueous and membrane phase aggregation.

The cost-effectiveness of the MobileMums intervention to increase physical activity among mothers with young children: A Markov model informed by a randomised controlled trial

Objectives: To determine the cost-effectiveness of the MobileMums intervention. MobileMums is a 12-week programme which assists mothers with young children to be more physically active, primarily through the use of personalised SMS text-messages. Design: A cost-effectiveness analysis using a Markov model to estimate and compare the costs and consequences of MobileMums and usual care. Setting: This study considers the cost-effectiveness of MobileMums in Queensland, Australia. Participants: A hypothetical cohort of over 36 000 women with a child under 1 year old is considered. These women are expected to be eligible and willing to participate in the intervention in Queensland, Australia. Data sources: The model was informed by the effectiveness results from a 9-month two-arm community-based randomised controlled trial undertaken in 2011 and registered retrospectively with the Australian Clinical Trials Registry (ACTRN12611000481976). Baseline characteristics for the model cohort, treatment effects and resource utilisation were all informed by this trial. Main outcome measures: The incremental cost per quality-adjusted life year (QALY) of MobileMums compared with usual care. Results: The intervention is estimated to lead to an increase of 131 QALYs for an additional cost to the health system of 1.1 million Australian dollars (AUD). The expected incremental cost-effectiveness ratio for MobileMums is 8608 AUD per QALY gained. MobileMums has a 98% probability of being cost-effective at a cost-effectiveness threshold of 64 000 AUD. Varying modelling assumptions has little effect on this result. Conclusions: At a cost-effectiveness threshold of 64 000 AUD, MobileMums would likely be a cost-effective use of healthcare resources in Queensland, Australia. Trial registration number: Australian Clinical Trials Registry; ACTRN12611000481976.

Theoretical studies on Beta-lactam antibiotics VI: Conformational analysis and structure-activity relationships of penicillin sulfoxides and cephalosporins

Conformational energy calculations were carried out on penicillin α-and Β-sulfoxides and δ2- and δ3-cephalosporins, in order to identify the structural features governing their biological activity. Results on penicillin Β-sulfoxide indicated that in its favoured conformation, the orientation of the aminoacyl group was different from the one required for biological activity. Penicillin α sulfoxide, like penicillin sulfide, favoured two conformations of nearly equal energies, but separated by a much higher energy barrier. The reduced activity of the sulfoxides despite the nonplanarity of their lactam peptide indicated that the orientations of the aminoacyl and carboxyl groups might also govern biological activity. δ3-cephalosporins favoured two conformations of nearly equal energies, whereas δ2-cephalosporins favoured only one conformation. The lactam peptide was moderately nonplanÄr in the former, but nearly planar in the latter. The differences in the.preferred orientations of the carboxyl group between penicillins and cephalosporins were correlated with the resistance of cephalosporins to penicillinases.

Isolation and Culture of a Thermophilic Fungus, Melanocarpus albomyces, and Factors Influencing the Production and Activity of Xylanase

Summary: An uncommon thermophilic fungus, Melanocarpus albomyces, was isolated from soil and compost by incubating samples in a glucose/sorbose/asparagine liquid medium, followed by enrichment culture in medium containing sugarcane bagasse as carbon source. The culture filtrate protein of the fungus grown in the presence of bagasse or xylose hydrolysed xylan and some other polysaccharides but cellulose was not hydrolysed. High extracellular xylanase (EC 3.2.1.8) activity was produced by cultures grown on xylose or hemicellulosic materials. The enzyme was induced in glucose-grown washed mycelia in response to addition of xylose or xylan but not by alkyl or aryl β-D-xylosides. Cultures produced higher enzyme yields in shaken flasks than in a fermenter. Gel-filtration chromatography of culture filtrate protein showed the presence of two isoenzymes of xylanase, whose relative proportions varied with the carbon source used for growth. The extent of hydrolysis of heteroxylans or the hemicellulosic fraction of bagasse by culture filtrate protein preparations was greater when the cultures had been grown on bagasse rather than xylose as the inducing substrate. The activity of xylanase preparations was increased when an exogenous β-glucosidase was added.

Glycogen debranching enzyme activity in the muscles of meat producing animals

Muscle glycogen exists in two forms: low molecular weight pro-glycogen and high molecular weight macro-glycogen. The degradation of glycogen to glucose 1 phosphate and free glucose is catalysed by glycogen phosphorylase together with glycogen debranching enzyme (GDE). The process in which glycogen is broken down via anaerobic pathways to lactate, results in the acidification of the muscles and has a great influence on meat quality. Thus, the overall aim of this thesis was to characterise the post mortem action of GDE in muscles of meat production animals (pigs, cattle and chickens). Interest was focused on the differences in GDE activity between fast twitch glycolytic muscles and slow twitch oxidative muscles. The effects of pH, temperature, RN genotype (PRKAG3 gene), and of time post mortem on GDE activity were also investigated. This thesis showed that there are differences in GDE activity between animal species and between different muscles of an animal. It was shown that in pigs and cattle, higher GDE activity and phosphorylase activity exists in the fast twitch glycolytic muscles than in slow twitch oxidative muscles of the same animal. Thus, the high activity of these enzymes enables a faster rate of glycogenolysis in glycolytic M. longissimus dorsi compared to oxidative M. masseter. In chicken muscles, the GDE activity was low compared to pig or cattle muscles. Furthermore, the GDE activity in the glycolytic M. pectoralis superficialis was lower than in more oxidative M. quadriceps femoris despite the high phosphorylase activity in the former. The relative ratios between phosphorylase and GDE activity were higher in fast twitch glycolytic muscles than in slow twitch oxidative muscles of all studied animals. This suggests that the relatively low GDE activity compared to the phosphorylase activity in fast twitch glycolytic muscles may be a protection mechanism in living muscle against a very fast pH decrease. Chilling significantly decreased GDE activity and below 15 C porcine GDE was almost inactive. The effect of pH on GDE activity was only minor at the range normally found in post mortem muscles (pH 7.4 to 5.0). The GDE activity remained level for several hours after slaughter. During the first hours post mortem, GDE activity was similar in RN- carrier pigs and in wild type pigs. However, the GDE activity declined faster in M. longissimus dorsi from wild type pigs than in the RN carrier pigs, the difference between genotypes was significant after 24 h post mortem. Pro-glycogen and macro-glycogen contents were higher, pH decrease was faster and ultimate pH was lower in RN- carrier pigs than in wild type pigs. In the RN- carriers, the prolonged high GDE activity level may enable an extended pH decrease and lower ultimate pH in their muscles. In conclusion, GDE is not the main factor determining the rate or the extent of post mortem glycogenolysis, but under certain conditions, such as in very fast chilling, the inhibition of GDE activity in meat may reduce the rate of pH decrease and result in higher ultimate pH. The rate and extent of pH decrease affects several meat quality traits.

An exploratory study to assess the activity of the acarine growth inhibitor, fluazuron, against Sarcoptes scabei infestation in pigs

Background: The most common treatments for scabies in human and veterinary settings are topical 5% permethrin or systemic treatment with ivermectin. However, these treatments have very little activity against arthropod eggs, and therefore repeated treatment is frequently required. In-vitro, biochemical and molecular studies have demonstrated that human mites are becoming increasingly resistant to both acaricides. To identify alternate acaricides, we undertook a pilot study of the in vivo activity of the benzoylphenyl urea inhibitor of chitin synthesis, fluazuron, in pigs with sarcoptic mange. Findings: Pigs (n = 5) were infested with S. scabei var suis, and randomised to treatment at the start of peak infestation with fluazuron at a dose of 10 mg/kg/day per os for 7 days (n = 3) or no treatment (n = 2). Clinical scores, skin scrapings for mite counts and blood sampling for pharmacokinetic analysis were undertaken. Fluazuron was well absorbed in treated pigs with measureable blood levels up to 4 weeks post treatment. No adverse effects were observed. Modest acaricidal activity of the compound was observed, with a reduction in severity of skin lesions in treated pigs, as well as a reduction in number of scabies mite's early life stages. Conclusions: The moderate efficacy of fluazuron against scabies mites indicates a lead to the development of alternate treatments for scabies, such as combination therapies that maybe applicable for human use in the future.

Investigation of surface activity and photoinduced diffusion of metals in solution deposited amorphous films of As2S3

Surface activity of solution deposited (SD) amorphous films of As2S3 has been investigated. Silver and copper are readily deposited on such films from appropriate aqueous ionic solutions. The metals diffuse into the films upon irradiation with energetic photons. Structure and properties of SD films have been investigated using electron microscopy, optical spectroscopy and differential scanning calorimetry. The amorphous films tend to crystallize upon metal diffusion. The stability of amorphous films, the deposition of metals on their active surfaces and the photo-induced diffusion may all be attributed to the presence or production of charged defects in amorphous chalcogenide films.

Economic theory informing approaches to phoenix activity in small business: A neo-Schumpeterian analysis

The adequacy and efficiency of existing legal and regulatory frameworks dealing with corporate phoenix activity have been repeatedly called into question over the past two decades through various reviews, inquiries, targeted regulatory operations and the implementation of piecemeal legislative reform. Despite these efforts, phoenix activity does not appear to have abated. While there is no law in Australia that declares ‘phoenix activity’ to be illegal, the behaviour that tends to manifest in phoenix activity can be capable of transgressing a vast array of law, including for example, corporate law, tax law, and employment law. This paper explores the notion that the persistence of phoenix activity despite the sheer extent of this law suggests that the law is not acting as powerfully as it might as a deterrent. Economic theories of entrepreneurship and innovation can to some extent explain why this is the case and also offer a sound basis for the evaluation and reconsideration of the existing law. The challenges facing key regulators are significant. Phoenix activity is not limited to particular corporate demographic: it occurs in SMEs, large companies and in corporate groups. The range of behaviour that can amount to phoenix activity is so broad, that not all phoenix activity is illegal. This paper will consider regulatory approaches to these challenges via analysis of approaches to detection and enforcement of the underlying law capturing illegal phoenix activity. Remedying the mischief of phoenix activity is of practical importance. The benefits include continued confidence in our economy, law that inspires best practice among directors, and law that is articulated in a manner such that penalties act as a sufficient deterrent and the regulatory system is able to detect offenders and bring them to account. Any further reforms must accommodate and tolerate legal phoenix activity, at least to some extent. Even then, phoenix activity pushes tolerance of repeated entrepreneurial failure to its absolute limit. The more limited liability is misused and abused, the stronger the argument to place some restrictions on access to limited liability. This paper proposes that such an approach is a legitimate next step for a robust and mature capitalist economy.

Exploring metrics to express energy expenditure of physical activity in youth

Background Several approaches have been used to express energy expenditure in youth, but no consensus exists as to which best normalizes data for the wide range of ages and body sizes across a range of physical activities. This study examined several common metrics for expressing energy expenditure to determine whether one metric can be used for all healthy children. Such a metric could improve our ability to further advance the Compendium of Physical Activities for Youth. Methods A secondary analysis of oxygen uptake (VO2) data obtained from five sites was completed, that included 947 children ages 5 to 18 years, who engaged in 14 different activities. Resting metabolic rate (RMR) was computed based on Schofield Equations [Hum Nutr Clin Nut. 39(Suppl 1), 1985]. Absolute oxygen uptake (ml.min-1), oxygen uptake per kilogram body mass (VO2 in ml.kg-1.min-1), net oxygen uptake (VO2 – resting metabolic rate), allometric scaled oxygen uptake (VO2 in ml.kg-0.75.min-1) and YOUTH-MET (VO2.[resting VO2] -1) were calculated. These metrics were regressed with age, sex, height, and body mass. Results Net and allometric-scaled VO2, and YOUTH-MET were least associated with age, sex and physical characteristics. For moderate-to-vigorous intensity activities, allometric scaling was least related to age and sex. For sedentary and low-intensity activities, YOUTH-MET was least related to age and sex. Conclusions No energy expenditure metric completely eliminated the influence of age, physical characteristics, and sex. The Adult MET consistently overestimated EE. YOUTH-MET was better for expressing energy expenditure for sedentary and light activities, whereas allometric scaling was better for moderate and vigorous intensity activities. From a practical perspective, The YOUTH-MET may be the more feasible metric for improving of the Compendium of Physical Activities for Youth.

Maternal and paternal support for physical activity and healthy eating in preschool children: A cross-sectional study

BACKGROUND Parental support is a key influence on children's health behaviours; however, no previous investigation has simultaneously explored the influence of mothers' and fathers' social support on eating and physical activity in preschool-aged children. This study evaluated the singular and combined effects of maternal and paternal support for physical activity (PA) and fruit and vegetable consumption (FV) on preschoolers' PA and FV. METHODS A random sample comprising 173 parent-child dyads completed validated scales assessing maternal and paternal instrumental support and child PA and FV behaviour. Pearson correlations, controlling for child age, parental age, and parental education, were used to evaluate relationships between maternal and paternal support and child PA and FV. K-means cluster analysis was used to identify families with distinct patterns of maternal and paternal support for PA and FV, and one-way ANOVA examined the impact of cluster membership on child PA and FV. RESULTS Maternal and paternal support for PA were positively associated with child PA (r = 0.37 and r = 0.36, respectively; P < 0.001). Maternal but not paternal support for FV was positively associated with child FV (r = 0.35; P < 0.001). Five clusters characterised groups of families with distinct configurations of maternal and paternal support for PA and FV: 1) above average maternal and paternal support for PA and FV, 2) below average maternal and paternal support for PA and FV, 3) above average maternal and paternal support for PA but below average maternal and paternal support for FV, 4) above average maternal and paternal support for FV but below average maternal and paternal support for PA, and 5) above average maternal support but below average paternal support for PA and FV. Children from families with above average maternal and paternal support for both health behaviours had higher PA and FV levels than children from families with above average support for just one health behaviour, or below average support for both behaviours. CONCLUSIONS The level and consistency of instrumental support from mothers and fathers for PA and FV may be an important target for obesity prevention in preschool-aged children.