Insights into the metabolism and behaviour of Varroa destructor mites from analysis of their waste excretions.

Varroa destructor mites (Acari: Varroidae) are harmful ectoparasites of Apis mellifera honey bees. Female foundresses of wax-capped pupal host cells and their daughters feed on host fluids from open wounds on the host's integument. Details of V. destructor mite nutrition are forthcoming, and little is known about the potential physical effects on hosts from mite feeding. Chemical analysis of waste excretions can infer details of animals' nutrition. Here, chemical analysis by high-performance liquid chromatography/mass spectrometry (HPLC-MS/MS) of mite excretions showed that the purine content of V. destructor waste consists of guanine with traces of hypoxanthine. Traces of uric acid and caffeine were also detected. Concentrations of guanine attenuated over time and excretions collected from senescing mites did not contain detectable guanine. Non-reproducing individual female mites maintained in vitro, housed in gelatin capsules and provided a honey bee pupa, deposited an average of nearly 18 excretions daily, mostly on the host's integument rather than on the capsule wall. The weight and volume of excretions suggest mites can consume nearly a microlitre of host fluids each day. Compounded over 10 days, this together with open wounds, could lead to substantial water loss and stress to developing pupae.

Using an in vitro system for maintaining Varroa destructor mites on Apis mellifera pupae as hosts: studies of mite longevity and feeding behavior.

Varroa destructor mites (varroa) are ectoparasites of Apis mellifera honey bees, and the damage they inflict on hosts is likely a causative factor of recent poor honey bee colony performance. Research has produced an arsenal of control agents against varroa mites, which have become resistant to many chemical means of their control, and other means have uncertain efficacy. Novel means of control will result from a thorough understanding of varroa physiology and behavior. However, robust knowledge of varroa biology is lacking; mites have very low survivability and reproduction away from their natural environment and host, and few tested protocols of maintaining mites in vitro are available as standardized methods for varroa research. Here, we describe the 'varroa maintenance system' (VMS), a tool for maintaining in vitro populations of varroa on its natural host, and present best practices for its use in varroa and host research. Additionally, we present results using the VMS from research of varroa and host longevity and varroa feeding behavior. Under these conditions, from two trials, mites lived an average of 12 and 14 days, respectively. For studies of feeding behavior, female mites inflicted wounds located on a wide range of sites on the host's integument, but preferred to feed from the host's abdomen and thorax. Originally in the phoretic-phase, female mites in VMS had limited reproduction, but positive instances give insights into the cues necessary for initiating reproduction. The VMS is a useful tool for laboratory studies requiring long-term survival of mites, or host-parasite interactions.

Deformed wing virus type A, a major honey bee pathogen, is vectored by the mite Varroa destructor in a non-propagative manner.

Honey bees, the primary managed insect pollinator, suffer considerable losses due to Deformed wing virus (DWV), an RNA virus vectored by the mite Varroa destructor. Mite vectoring has resulted in the emergence of virulent DWV variants. The basis for such changes in DWV is poorly understood. Most importantly, it remains unclear whether replication of DWV occurs in the mite. In this study, we exposed Varroa mites to DWV type A via feeding on artificially infected honey bees. A significant, 357-fold increase in DWV load was observed in these mites after 2 days. However, after 8 additional days of passage on honey bee pupae with low viral loads, the DWV load dropped by 29-fold. This decrease significantly reduced the mites' ability to transmit DWV to honey bees. Notably, negative-strand DWV RNA, which could indicate viral replication, was detected only in mites collected from pupae with high DWV levels but not in the passaged mites. We also found that Varroa mites contain honey bee mRNAs, consistent with the acquisition of honey bee cells which would additionally contain DWV replication complexes with negative-strand DWV RNA. We propose that transmission of DWV type A by Varroa mites occurs in a non-propagative manner.

Insights into the feeding behaviors and biomechanics of Varroa destructor mites on honey bee pupae using electropenetrography and histology.

Feeding behaviors and biomechanics of female Varroa destructor mites are revealed from AC-DC electropenetrography (EPG) recordings of mites feeding from Apis mellifera honey bee pupae and histology of mite internal ingestion apparatus. EPG signals characteristic of arthropod suction feeding (ingestion) were identified for mites that fed on pupae during overnight recordings. Ingestion by these mites was confirmed afterwards by observing internally fluorescent microbeads previously injected into their hosts. Micrographs of internal ingestion apparatus illustrate the connection between a gnathosomal tube and a pharyngeal lumen, which is surrounded by alternating dilator and constrictor muscles. Inspection of EPG signals showed the muscularized mite pharyngeal pump operates at a mean repetition rate of 4.5 cycles/s to ingest host fluids. Separate feeding events observed for mites numbered between 23 and 33 over approximately 16 h of recording, with each event lasting ~10 s. Feeding events were each separated by ~2 min. Consecutive feeding events separated by either locomotion or prolonged periods of quiescence were grouped into feeding bouts, which ranged in number from one to six. Statistical analyses of EPG data revealed that feeding events were prolonged for mites having lower pharyngeal pump frequencies, and mites having prolonged feeding events went unfed for significantly more time between feeding events. These results suggest that mites may adjust behaviors to meet limitations of their feeding apparatus to acquire similar amounts of food. Data reported here help to provide a more robust view of Varroa mite feeding than those previously reported and are both reminiscent of, as well as distinct from, some other acarines and fluid-feeding insects.

Argasid and ixodid systematics: Implications for soft tick evolution and systematics, with a new argasid species list.

The systematics of the genera and subgenera within the soft tick family Argasidae is not adequately resolved. Different classification schemes, reflecting diverse schools of scientific thought that elevated or downgraded groups to genera or subgenera, have been proposed. In the most recent classification scheme, Argas and Ornithodoros are paraphyletic and the placement of various subgenera remains uncertain because molecular data are lacking. Thus, reclassification of the Argasidae is required. This will enable an understanding of soft tick systematics within an evolutionary context. This study addressed that knowledge gap using mitochondrial genome and nuclear (18S and 28S ribosomal RNA) sequence data for representatives of the subgenera Alectorobius, Argas, Chiropterargas, Ogadenus, Ornamentum, Ornithodoros, Navis (subgen. nov.), Pavlovskyella, Persicargas, Proknekalia, Reticulinasus and Secretargas, from the Afrotropical, Nearctic and Palearctic regions. Hard tick species (Ixodidae) and a new representative of Nuttalliella namaqua (Nuttalliellidae), were also sequenced with a total of 83 whole mitochondrial genomes, 18S rRNA and 28S rRNA genes generated. The study confirmed the utility of next-generation sequencing to retrieve systematic markers. Paraphyly of Argas and Ornithodoros was resolved by systematic analysis and a new species list is proposed. This corresponds broadly with the morphological cladistic analysis of Klompen and Oliver (1993). Estimation of divergence times using molecular dating allowed dissection of phylogeographic patterns for argasid evolution. The discovery of cryptic species in the subgenera Chiropterargas, Ogadenus and Ornithodoros, suggests that cryptic speciation is common within the Argasidae. Cryptic speciation has implications for past biological studies of soft ticks. These are discussed in particular for the Ornithodoros (Ornithodoros) moubata and Ornithodoros (Ornithodoros) savignyi groups.

Effect of plasma homocysteine concentration on early and late events in patients with acute coronary syndromes.

BACKGROUND: Although a raised plasma homocysteine is a risk factor for vascular disease, it is not known whether it is associated with an adverse cardiac outcome in patients admitted with acute coronary syndromes. We evaluated the relationship between plasma homocysteine and short-term (28 days) and long-term (median 2.5 years) prognosis in acute coronary syndromes. METHODS AND RESULTS: We evaluated the relationship of quintiles of homocysteine to fatal and nonfatal coronary disease early (28 days) and late (29 days to a median of 2. 5 years) after admission to a single unit of patients with unstable angina (n=204) and myocardial infarction (n=236). The end points studied were cardiac death (n=67) and/or myocardial (re)infarction (n=30). Cox regression and logistic regression were used to estimate the relationship of homocysteine to coronary events. The event rate within the first 28 days (22 cardiac deaths and 5 nonfatal infarctions) was not related to the admission homocysteine level. In the 203 unstable angina and 214 myocardial infarction survivors, an apparent threshold effect was seen on long-term follow-up, with a significant step-up in the frequency of events between the lowest 3 quintiles (14 cardiac deaths and 11 nonfatal infarctions) and the upper 2 quintiles (31 fatal and 12 nonfatal events). Patients in the upper 2 quintiles (>12.2 micromol/L) had a 2.6-fold increase in the risk of a cardiac event (95% CI, 1.5 to 4.3, P<0.001). CONCLUSIONS: Elevated total homocysteine levels on admission strongly predict late cardiac events in acute coronary syndromes.

Interactions between tussock grass (Poa spp.) and Eucalyptus pauciflora seedlings near treeline in South-Eastern Australia.

Observations of tussock grasses (mainly Poa species) and tree seedlings (Eucalyptus pauciflora) growing near treeline suggested that the tussocks may physically protect and compete with the tree seedlings. An analysis of nearest neighbour data from sites burnt in 1972-3 showed the there is a minimum separation between seedlings and tussocks, indicating that competition is taking place. Correlation and principal components analyses show that seedlings growing close to tussocks tend to be taller, with fewer stems and leaves than those growing further away. This same trend from tall, few-stemmed individuals to shorter multistemmed individuals also occurs with an increase in altitude. It is concluded that the trend in habit is related to exposure to environmental extremes. The concept of the regeneration niche and its application to E. pauciflora seedlings is discussed.

Cost-Effectiveness of Budesonide Controlled Ileal Release (CIR) Capsules as Maintenance Therapy versus No Maintenance Therapy for Ileocaecal Crohn's Disease in Sweden.

A decision-analytic model was designed to estimate the associated costs and outcomes of maintenance therapy for Crohn's disease with budesonide controlled ileal release (CIR) capsules (Entocort((R)) capsules, Astra Draco, Lund, Sweden) versus no maintenance therapy. A third-party payer perspective was adopted to compare the direct costs associated with the medication and healthcare resource use for each therapy over a period of 12 four-week cycles. The costs of routine patient care and the consequences of failure, in terms of relapses, acute therapies, hospitalisations and surgery, were included. The outcome was measured as the average number of days in remission per patient per 12-cycle period. Based on the assumptions in the model, the results show that budesonide CIR capsules are associated with a reduction of 16.6 (26%) days in relapse, i.e. a 6% increase in days in remission, over a one-year period compared with no maintenance therapy. Direct healthcare costs are increased by 6% or Swedish kronor (SEK) 1673 ($US1 ~ SEK7.60). Overall, the model shows that there are substantial (non-drug associated) cost offsets from using budesonide CIR capsules as maintenance therapy in Crohn's disease. These cost offsets, in addition to improvements in patients' well-being and quality of life, indicate that maintenance therapy is cost effective compared with no maintenance therapy. The cost per added day in remission is relatively modest (SEK101 ~ $US13). If indirect costs are added to the calculation, it is realistic to argue that a net saving to society would be most likely.

An investigation of the physico-chemical basis of foaming in fungal fermentations.

A detailed physico-chemical analysis of two foaming fungal fermentations was carried out to identify that key groups of compounds responsible for foam formation. Fermentations were carried out on a 20-L scale in a stirred aerated tank, over 7 days, using a commercial, defined medium. The organisms investigated were Penicillium herqueii, a hyphomycete, and an unidentified Ingoldian fungus. Samples of broth and, where possible, foam were analyzed to determine which groups of compounds were concentrated into generated foams. Surface tension, bulk viscosity, and antifoam A concentration were additionally determined in broth samples. To date the cause of foaming in fermentations has been attributed to the surfactant properties of extracellular proteins. This assumption was tested and found to be incomplete as many additional groups of biochemicals were found to be enriched into the foam. The results of the investigation revealed the presence of proteins, carbohydrates, alpha-keto acids, and lipophilic biosurfactants, particularly extracellular pigments, enriched within stable foams. (c) 1994 John Wiley & Sons, Inc.

Transuretero-ureterostomy: a review of 253 cases.

OBJECTIVES: To review our experience of transuretero-ureterostomy (TUU), which can be a dangerous procedure if a problem arises with the anastomosis, because both upper urinary tracts are put at risk to deal with a problem that initially affected only one side. PATIENTS AND METHODS: TUU was performed in 253 patients following undiversion, trauma or strictures of the distal ureter, with a Mitrofanoff-type of continent urinary diversion, or otherwise during reconstructive urological surgery, mainly in association with cystectomy and substitution cystoplasty. The patients were followed and complications or problems reviewed. RESULTS: Five patients had problems with the distal ureter below the TUU and one had problems as a result of stone disease in the transposed ureter some distance proximal to the TUU, but there were no long-term complications as a direct result of the TUU. CONCLUSIONS: Providing the anastomosis is stented until there is radiological evidence of healing of the TUU, then TUU is a safe and reliable procedure.

Physicochemical properties of the matrix proteins of three main culture vehicles.

The protein components of three industrial recombinant expression systems: Escherichia coli, Saccharomyces cerevisiae, and a mammalian cell culture supernatant of CHO cells were characterized in terms of their molecular weight, isoelectric point, and relative surface hydrophobicity. Identification of individual proteins was done by reference to their position in protein band profiles by polyacrylamide gel electrophoresis (PAGE) of the crude material. This permitted a rapid and facile assignment of quantitative values for these three parameters to all the major protein components in these materials. Because it is the indigenous proteins in expression systems that will form the bulk of any impurities in the product, once the values of these parameters are known for any target recombinant protein, the data obtained will enable appropriate expression systems to be chosen for minimizing amounts of potential contaminants and reducing downstream processing requirements and costs. The data will also indicate which fractionation steps (i.e., charge, size or hydrophobicity-based) are likely to be best for distinguishing between target and contaminant proteins, thus aiding and early removal of the maximum quantities of undesired protein to bring subsequent bioseparation steps down in scale and cost and up in terms of efficiency.

Botulinum toxin type A in the management of equinus in children with cerebral palsy: an evidence-based economic evaluation.

INTRODUCTION: The aim of this study was to compare two methods of conservative management of calf spasticity and equinus gait--intramuscular injection of botulinum toxin type A (BTX-A) and serial casting. An economic evaluation framework was adopted to assess whether BTX-A offers value for money in the management of equinus gait due to calf spasticity in children with cerebral palsy. Short- to medium-term health care costs and outcomes were estimated for the comparison. This study was embarked upon to provide clinical and economic data as part of an application to the Pharmaceutical Benefits Advisory Committee (PBAC) for the reimbursement of BOTOX by the Australian Commonwealth Government. This is the primary mechanism for reimbursement of pharmaceuticals in Australia, as they are not routinely reimbursed through health insurance companies. The perspective of the analysis was that of the Australian health system. METHODOLOGY: Randomized controlled trials (RCTs) exist comparing one treatment cycle of BTX-A with serial casting (Corry et al., 1998; Flett et al., 1999). A long-term prospective study provided data on multiple cycles of BTX-A treatment in a more naturalistic setting (Boyd et al., 1999). A simple economic modelling approach was used to establish resource utilization by treatment arm. Only direct medical costs were considered (BTX-A, medical personnel time and medical consumables). MAIN MEASURES: Clinical efficacy was obtained from the randomized controlled trials (Corry et al., 1998; Flett et al., 1999). Patient/parent preference was obtained from long-term follow-up (Corry et al., 1998) and a preference questionnaire (Flett et al., 1999). Australian treatment patterns and patient demographics were obtained from the naturalistic study (Boyd et al., 1999). RESULTS: The RCTs demonstrated equivalent efficacy of BTX-A and serial casting; however, with BTX-A the effect lasted longer and was clearly the preferred treatment. For patients with hemiplegia the costs of an episode of treatment with BTX-A or serial casting are ($AUD) $595 and $435, respectively, and thus the additional costs associated with BTX-A are $160. The corresponding costs for patients with diplegia are $1045 for BTX-A treatment and $870 for serial casting and thus the additional cost associated with BTX-A is $175. With an overall treatment duration of 3.7 years and an average treatment interval of 10 months, patients would receive an average of 5.4 treatments. Thus, for patients with hemiplegia the total additional cost, discounted at 5% annually, for BTX-A is $793. For patients with diplegia the total additional cost for BTX-A is $867. CONCLUSIONS AND CLINICAL INTERPRETATIONS: BTX-A is an effective, safe and acceptable treatment modality and is associated with only a modest increase in direct medical costs per child per year. BTX-A can be considered a valuable and cost-effective treatment in the conservative management of equinus due to calf spasticity in children with cerebral palsy. This conclusion is supported by the acceptance of the Pharmaceutical Benefits Advisory Committee (PBAC) recommendation that BOTOX should attract a full Government subsidy in Australia.

Immunolocalization of vitamin D receptor and calbindin-D28k in human tooth germ.

The role of vitamin D in ameloblasts and odontoblasts has been studied experimentally in rodents. Dental dysplasias have also been reported in clinical studies of children with rickets. Vitamin D acts via a nuclear receptor which binds the major metabolite, 1,25-dihydroxyvitamin D3, and positively or negatively controls the expression of specific genes. The most extensively studied markers of 1,25-dihydroxyvitamin D3 action are calbindin-D9k, calbindin-D28k, and osteocalcin. Therefore, to study in more detail the potential role of 1,25-dihydroxyvitamin D3 in human dental development, 1,25-dihydroxyvitamin D3 receptor (VDR) was localized by immunofluorescence in forming teeth (8-26 wk of gestation). Calbindin-D28k was also mapped by immunoperoxidase in antenatal and postnatal forming and formed teeth. VDR were detected in both dental epithelium and mesenchyme of bud, cap, and bell stages of tooth germs. Nuclei of overtly differentiated ameloblasts and odontoblasts were also immunostained. Calbindin-D28k was present in differentiated ameloblasts and odontoblasts. The presence of VDR and calbindin-D28k in ameloblasts and odontoblasts suggests that 1,25-dihydroxyvitamin D3 may contribute to the regulation of enamel and dentin formation, as classically reported for bone formation. Finally, the early appearance of VDR supports the concept that 1,25-dihydroxyvitamin D3 may also control forward stages of tooth crown development in humans.

Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems.

Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains uncertain. Here we provide an overview of the current state of knowledge of global and regional patterns of carbon exchange by terrestrial ecosystems. Atmospheric carbon dioxide and oxygen data confirm that the terrestrial biosphere was largely neutral with respect to net carbon exchange during the 1980s, but became a net carbon sink in the 1990s. This recent sink can be largely attributed to northern extratropical areas, and is roughly split between North America and Eurasia. Tropical land areas, however, were approximately in balance with respect to carbon exchange, implying a carbon sink that offset emissions due to tropical deforestation. The evolution of the terrestrial carbon sink is largely the result of changes in land use over time, such as regrowth on abandoned agricultural land and fire prevention, in addition to responses to environmental changes, such as longer growing seasons, and fertilization by carbon dioxide and nitrogen. Nevertheless, there remain considerable uncertainties as to the magnitude of the sink in different regions and the contribution of different processes.