Prophylactic and therapeutic efficacy of Australian-registered insecticide formulations against Old World screwworm (Chrysomya bezziana) infestation.

OBJECTIVE: To determine the prophylactic and therapeutic efficacy of Australian-registered insecticide formulations against Old World screwworm (OWS) myiases for potential use in screwworm containment and eradication programs. METHODS: The longevity of protection provided by six insecticidal formulations (subcutaneous ivermectin, doramectin and abamectin, a topically applied aqueous formulation of spinosad, ivermectin controlled-release capsule and a dicyclanil spray-on formulation) was tested using implants of 1st-instar OWS larvae on Javanese thin-tail sheep. Therapeutic efficacy of four formulations (topical ivermectin, chlorfenvinphos/cypermethrin mixture, aerosol spinosad formulation and a formulation containing propetamphos and eucalyptus oil) was tested against 2- and 4-day-old OWS strikes. RESULTS: Both the ivermectin capsule and dicyclanil spray-on formulation gave 100% protection against screwworm implants for the full 12 weeks of the study. Ivermectin, doramectin and abamectin administered SC all gave 100% protection at 3 days post-treatment, but at 2 weeks the protection had become incomplete. Spinosad dipping did not give complete protection at any time. All four therapeutic treatments gave complete resolution of 2-day-old strikes and topical ivermectin, spinosad and chlorfenvinphos/cypermethrin, but not the propetamphos/eucalyptus oil formulation, gave complete resolution of all 4-day-old strikes. CONCLUSION: Dicyclanil spray-on and ivermectin capsule formulations, both registered for use in sheep, but not for cattle or other livestock species, gave much longer protection against screwworm implants than the currently recommended SC ivermectin. Pre-emptive action to facilitate rapid deployment of these formulations in the event of a screwworm incursion is urgently needed.

Cattle herd inspections and fly trapping for the detection of the Old World screw-worm fly (Chrysomya bezziana).

OBJECTIVES: To compare the sensitivity of inspections of cattle herds and adult fly trapping for detection of the Old World screw-worm fly (OWS). PROCEDURES: The incidence of myiases on animals and the number of OWS trapped with LuciTrap®/Bezzilure were measured concurrently on cattle farms on Sumba Island (Indonesia) and in peninsular Malaysia (two separate periods for the latter). The numbers of animal inspections and traps required to achieve OWS detection at the prevalent fly densities were calculated. RESULTS: On Sumba Island, with low-density OWS populations, the sensitivity of herd inspections and of trapping for OWS detection was 0.30 and 0.85, respectively. For 95% confidence of detecting OWS, either 45 inspections of 74 animals or trapping with 5 sets of 4 LuciTraps for 14 days are required. In Malaysia, at higher OWS density, herd inspections of 600 animals (twice weekly, period 1) or 1600 animals (weekly, period 2) always detected myiases (sensitivity = 1), while trapping had sensitivities of 0.89 and 0.64 during periods 1 and 2, respectively. For OWS detection with 95% confidence, fewer than 600 and 1600 animals or 2 and 6 LuciTraps are required in periods 1 and 2, respectively. CONCLUSIONS: Inspections of cattle herds and trapping with LuciTrap and Bezzilure can detect OWS populations. As a preliminary guide for OWS detection in Australia, the numbers of animals and traps derived from the Sumba Island trial should be used because the prevailing conditions better match those of northern Australia.

Avulsion fragmentation of the tibial tuberosity apophysis and associated patellar tendon enthesopathy in a skeletally immature dog.

A 9.5-month-old, female entire, 31.3 kg crossbred dog was presented with a 12 week history of moderate weight-bearing right pelvic limb lameness. Radiographic, computed tomographic, and ultrasonographic imaging revealed progressive avulsion fragmentation of the right tibial tuberosity apophysis and a patellar tendon insertional enthesopathy without physeal involvement. Conservative management was successful in achieving a good clinical outcome. A progressive avulsion of the contralateral proximal tibial physes that occurred concurrently resulted in development of an excessive tibial plateau slope angle. The additional development of a moderate left distal femoral varus deformity was surgically corrected. This is the first report of a progressive, traction injury to the tibial tuberosity apophysis in a dog that appears clinically and radiographically very similar to Osgood-Schlatter disease in humans.

Interaction between the BDNF gene Val/66/Met polymorphism and morning cortisol levels as a predictor of depression in adult women.

BACKGROUND: Common genetic variants, such as the brain-derived neurotrophic factor (BDNF) Val/66/Met polymorphism (rs6265), are known to interact with environmental factors such as early adversity to increase the risk of subsequent major depression. Much less is known about how they interact with individual differences in cortisol, although these also represent a risk for major depression. AIMS: To determine whether this BDNF variant moderated the risk represented by higher levels of morning salivary cortisol in adult women. METHOD: We recruited 279 premenopausal women who were at high risk of major depressive disorder because of either negative self-evaluation, unsupportive core relationship or chronic subclinical symptoms of depression or anxiety. Morning salivary cortisol was measured daily for up to 10 days at entry. Participants were followed up for about 12 months by telephone calls at 3-4 monthly intervals. Major depression and severe life events were assessed through interviews at baseline and follow-up; DNA was obtained from the saliva. RESULTS: There were 53 onsets (19%) of depressive episodes during follow-up. There was a significant U-shaped relationship between adjusted morning cortisol levels at baseline and the probability of depression onset during follow-up. In total, 51% experienced at least one severe life event/difficulty, and this strongly predicted subsequent onsets of depressive episodes. The BDNF Val/66/Met genotype was not directly associated with onsets of depression or with cortisol levels, but there was significant interaction between Val/66/Met and cortisol: the association between baseline cortisol and depression was limited to those with the Val/66/Val variant. There was no interaction between life events and either this BDNF polymorphism or cortisol levels. CONCLUSIONS: Morning salivary cortisol interacts with the BDNF Val/66/Met polymorphism in predicting new depressive episodes. This paper adds to the evidence that single gene polymorphisms interact with endogenous factors to predict depression.

Field assessment of synthetic attractants and traps for the Old World screw-worm fly, Chrysomya bezziana.

The performance of newly developed trapping systems for the Old World screw-worm fly, Chrysomya bezziana has been determined in field trials on cattle farms in Malaysia. The efficacy of non-sticky traps and new attractants to trap C. bezziana and non-target flies was compared with the standard sticky trap and Swormlure. The optimal trap was a modified LuciTrap(®) with a new attractant mixture, Bezzilure-2. The LuciTrap/Bezzilure-2 caught on average 3.1 times more C. bezziana than the sticky trap with Swormlure (P<0.05) and provided selectivity for C. bezziana against Chrysomya megacephala and Chrysomya rufifacies with factors of 5.9 and 6.4, respectively. The LuciTrap also discriminates with factors of 90 and 3.6 against Hemipyrellia sp. and sarcophagid flesh flies respectively, compared to the sticky trap. The LuciTrap/Bezzilure-2 system is recommended for screwworm fly surveillance as it is more attractive and selective towards C. bezziana and provides flies of better quality for identification than the sticky trap.

Nuisance flies on Australian cattle feedlots: immature populations.

Species composition, seasonality and distribution of immature fly populations on a southern Queensland feedlot during 2001-2003 were determined. Similar data were collected on feedlots in central New South Wales and central Queensland. The fly species recovered in the highest numbers were Musca domestica L. (Diptera: Muscidae), Stomoxys calcitrans L. (Diptera: Muscidae) and Physiphora clausa Macquart (Diptera: Ulidiidae). Houseflies were the dominant species at all feedlots. Houseflies preferred the warmer months from October to June, but stable flies preferred the cooler months and peaked in spring (September-November) and autumn (March-May). Larval abundance ratings recorded in the feedlot and numbers of larvae extracted in the laboratory from corresponding samples followed similar trends. Larvae of M. domestica were most abundant in the hospital and induction area and least abundant in horse stables and yards. Pupae of M. domestica were abundant in the hospital and induction area and drains, but least abundant in horse stables and yards. Larvae of S. calcitrans were most abundant in drains and least abundant in horse stables and yards. Pupae of S. calcitrans were most numerous in drains and least numerous in old cattle pens. Feedlot design and management had little effect on fly reduction.

Mechanism of resistance to synthetic pyrethroids in buffalo flies in south-east Queensland.

Resistance to synthetic pyrethroids (SP) was first recorded in buffalo flies in Australia in 1980, associated with previous use of DDT and fenvalerate. By the 1990s, resistance was widespread. Resistance to SP in the related horn fly of the Americas is associated with kdr and super-kdr mutations in a gene encoding for a voltage-gated sodium channel. We describe 7-20-fold resistance to SP in buffalo flies from south-east Queensland, present evidence of flies that are heterozygous resistant at the kdr locus and show an increase in the frequency of the resistant allele 1 month after treatment of cattle with SP.

Specific detection of the Old World screwworm fly, Chrysomya bezziana, in bulk fly trap catches using real-time PCR.

The Old World screwworm fly (OWS), Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), is a myiasis-causing blowfly of major concern for both animals and humans. Surveillance traps are used in several countries for early detection of incursions and to monitor control strategies. Examination of surveillance trap catches is time-consuming and is complicated by the presence of morphologically similar flies that are difficult to differentiate from Ch. bezziana, especially when the condition of specimens is poor. A molecular-based method to confirm or refute the presence of Ch. bezziana in trap catches would greatly simplify monitoring programmes. A species-specific real-time polymerase chain reaction (PCR) assay was designed to target the ribosomal DNA internal transcribed spacer 1 (rDNA ITS1) of Ch. bezziana. The assay uses both species-specific primers and an OWS-specific Taqman((R)) MGB probe. Specificity was confirmed against morphologically similar and related Chrysomya and Cochliomyia species. An optimal extraction protocol was developed to process trap catches of up to 1000 flies and the assay is sensitive enough to detect one Ch. bezziana in a sample of 1000 non-target species. Blind testing of 29 trap catches from Australia and Malaysia detected Ch. bezziana with 100% accuracy. The probability of detecting OWS in a trap catch of 50 000 flies when the OWS population prevalence is low (one in 1000 flies) is 63.6% for one extraction. For three extractions (3000 flies), the probability of detection increases to 95.5%. The real-time PCR assay, used in conjunction with morphology, will greatly increase screening capabilities in surveillance areas where OWS prevalence is low.

Strategic use of crutching and dicyclanil to protect unmulesed sheep against breech strike.

OBJECTIVE: To test strategies for the application of dicyclanil and mid-season crutching to maximise protection of unmulesed sheep against breech strike. PROCEDURE: Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep. RESULTS: All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction (P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks. CONCLUSION: In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing.

Solid-state quantum computer based on scanning tunneling microscopy.

We propose a solid-state nuclear-spin quantum computer based on application of scanning tunneling microscopy (STM) and well-developed silicon technology. It requires the measurement of tunneling-current modulation caused by the Larmor precession of a single electron spin. Our envisioned STM quantum computer would operate at the high magnetic field (approximately 10 T) and at low temperature approximately 1 K.

Morning cortisol as a risk factor for subsequent major depressive disorder in adult women.

BACKGROUND: Whether individual differences in cortisol contribute to subsequent major depressive disorder (MDD) is unknown. AIMS: To determine whether premorbid levels of salivary cortisol and dehydroepiandrosterone (DHEA) were associated with subsequent MDD and how these related to psychosocial factors known to increase the risk for MDD. METHOD: Adult women (n=116) were recruited from general practices. None was currently depressed; 83 were 'psychosocially vulnerable' to MDD, 33 were not. Salivary steroids (cortisol and DHEA at 08.00 h and 20.00 h), recent life events, current mood and social support were assessed at entry. Onset of MDD was recorded during 13 months' follow-up. RESULTS: There were no associations between salivary cortisol or DHEA and recent life events or vulnerability. Twenty-eight onsets of MDD occurred during the follow-up period. This was associated with: severe adverse life events and difficulties during the follow-up period; mean morning cortisol levels at entry; and the presence of any of three vulnerability factors. CONCLUSIONS: Individual differences in morning salivary cortisol levels may represent an independent risk factor for subsequent MDD. The origin of these differences in cortisol is not yet understood.

Schizosaccharomyces pombe Hsk1p is a potential cds1p target required for genome integrity.

The fission yeast Hsk1p kinase is an essential activator of DNA replication. Here we report the isolation and characterization of a novel mutant allele of the gene. Consistent with its role in the initiation of DNA synthesis, hsk1(ts) genetically interacts with several S-phase mutants. At the restrictive temperature, hsk1(ts) cells suffer abnormal S phase and loss of nuclear integrity and are sensitive to both DNA-damaging agents and replication arrest. Interestingly, hsk1(ts) mutants released to the restrictive temperature after early S-phase arrest in hydroxyurea (HU) are able to complete bulk DNA synthesis but they nevertheless undergo an abnormal mitosis. These findings indicate a second role for hsk1 subsequent to HU arrest. Consistent with a later S-phase role, hsk1(ts) is synthetically lethal with Deltarqh1 (RecQ helicase) or rad21ts (cohesin) mutants and suppressed by Deltacds1 (RAD53 kinase) mutants. We demonstrate that Hsk1p undergoes Cds1p-dependent phosphorylation in response to HU and that it is a direct substrate of purified Cds1p kinase in vitro. These results indicate that the Hsk1p kinase is a potential target of Cds1p regulation and that its activity is required after replication initiation for normal mitosis.

Regulation of chromosome replication.

The initiation of DNA replication in eukaryotic cells is tightly controlled to ensure that the genome is faithfully duplicated once each cell cycle. Genetic and biochemical studies in several model systems indicate that initiation is mediated by a common set of proteins, present in all eukaryotic species, and that the activities of these proteins are regulated during the cell cycle by specific protein kinases. Here we review the properties of the initiation proteins, their interactions with each other, and with origins of DNA replication. We also describe recent advances in understanding how the regulatory protein kinases control the progress of the initiation reaction. Finally, we describe the checkpoint mechanisms that function to preserve the integrity of the genome when the normal course of genome duplication is perturbed by factors that damage the DNA or inhibit DNA synthesis.

Befriending as an intervention for chronic depression among women in an inner city. 1: Randomised controlled trial.

BACKGROUND: Earlier work on the protective role of social support in onset and course of depressive disorder suggested that its provision might be relevant for outcome. AIMS: To evaluate volunteer befriending as an intervention among women with chronic depression in inner London. METHOD: A randomised controlled trial, with a waiting list control design, with outcome measured as Present State Examination (PSE)-based full or partial remission after one year. RESULTS: A statistically significant effect upon remission was found for befriending. Other treatments monitored naturalistically did not relate to remission, nor did initial duration of chronic episode or comorbidity, but there was an association with initial PSE score. The findings are discussed in relation to standard drug-trial results and to another befriending intervention with the elderly. CONCLUSIONS: The results are not unpromising. Additional trials with less restricted intake conditions, and in more naturalistic general practice settings, might confirm volunteer befriending as a useful adjunct to current treatments.

Befriending as an intervention for chronic depression among women in an inner city. 2: Role of fresh-start experiences and baseline psychosocial factors in remission from depression.

BACKGROUND: Volunteer befriending promoted remission of chronic depression when clinical and other treatment variables were controlled. AIMS: To examine the role of other psychosocial factors relevant for outcome. METHOD: Factors measured at baseline interview were examined in multivariate analyses along with psychosocial factors occurring during follow-up, such as 'fresh-start' experiences and new severe events and difficulties. RESULTS: Fresh-start experiences and a standard attachment style were found to enhance chances of remission, with new severe stressors and markedly poor coping strategies liable to prevent it, with volunteer befriending continuing to play a role. CONCLUSIONS: The positive result reported in the preceding paper is unlikely to be an artefact. However, fresh-start experiences, absence of new severe stressors and standard attachment style were more important predictors of remission. This knowledge might profitably be incorporated into the evaluation of existing treatments.

Cell cycle regulation of Dfp1, an activator of the Hsk1 protein kinase.

In fission yeast, the Hsk1 protein kinase is essential for the initiation of DNA replication. We have shown previously that Hsk1 forms a heterodimeric complex with the regulatory subunit, Dfp1. In this report we describe the further characterization of Dfp1. Reconstitution experiments with purified proteins indicate that Dfp1 is necessary and sufficient to activate Hsk1 phosphorylation of exogenous substrates, such as the Schizosaccharomyces pombe minichromosome maintenance protein Cdc19. The dfp1(+) gene is essential for viability of S. pombe, and depletion of the Dfp1 protein significantly delays the onset of S phase. Dfp1 is a phosphoprotein in vivo and becomes hyperphosphorylated when cells are blocked in S phase by treatment with the DNA synthesis inhibitor hydroxyurea. Hyperphosphorylation in S phase depends on the checkpoint kinase Cds1. The abundance of Dfp1 varies during progression through the cell cycle. The protein is absent when cells are arrested in G(1) phase. When cells are released into the cell cycle, Dfp1 appears suddenly at the G(1)/S transition, coincident with the initiation of DNA replication. The absence of Dfp1 before S phase is due largely, but not exclusively, to posttranscriptional regulation. We propose that cell cycle-regulated activation of Dfp1 expression at the G(1)/S transition results in activation of the Hsk1 protein kinase, which, in turn, leads to the initiation of DNA replication.

Purification of Hsk1, a minichromosome maintenance protein kinase from fission yeast.

Members of the Cdc7 family of protein kinases are essential for the initiation of DNA replication in all eukaryotes, but their precise biochemical function is unclear. We have purified the fission yeast Cdc7 homologue Hsk1 approximately 30,000-fold, to near homogeneity. Purified Hsk1 has protein kinase activity on several substrates and is capable of autophosphorylation. Point mutations in highly conserved regions of Hsk1 inactivate the kinase in vitro and in vivo. Overproduction of two of the mutant hsk1 alleles blocks initiation of DNA replication and deranges the mitotic checkpoint, a phenotype consistent with a role for Hsk1 in the early stages of initiation. The purified Hsk1 kinase can be separated into two active forms, a Hsk1 monomer and a heterodimer consisting of Hsk1 complexed with a co-purifying polypeptide, Dfp1. Association with Dfp1 stimulates phosphorylation of exogenous substrates but has little effect on autokinase activity. We have identified Dfp1 as the fission yeast homologue of budding yeast Dbf4. Purified Hsk1 phosphorylates the Cdc19 (Mcm2) subunit of the six-member minichromosome maintenance protein complex purified from fission yeast. Since minichromosome maintenance proteins have been implicated in the initiation of DNA replication, the essential function of Hsk1 at the G1/S transition may be mediated by phosphorylation of Cdc19. Furthermore, the phosphorylation of critical substrates by Hsk1 kinase is likely regulated by association with a Dbf4-like co-factor.

Genetic and population perspectives on life events and depression.

Population comparisons of epidemiological surveys using the same investigator-based measures suggest that large differences are possible in the experience of clinically relevant depression and of life events capable of provoking such episodes. It is argued that, given the great majority of onsets in the various populations were provoked by a life event, the differences in the experience of depression are likely to have been largely the result of psychosocial factors. Moreover, this interpretation would still be likely to hold even if heritability (h2) coefficients for depression within the component populations were substantial. The same argument would hold for the interpretation of the across-population differences in the experience of life events. New material concerning the differing experience across populations of humiliation/entrapment events, known to be particularly depressogenic, is also presented and the implications of the findings for future aetiological research discussed.

Gender differences in marital support following a shared life event.

Previous work has established that women with good marriages are less at risk of depression of clinical severity following a crisis than women in poor quality relationships. Evidence for such protectiveness is less clear for men. The paper examines the relationship between marital quality, onset of depression, and gender following a severely threatening life event. The results show that good quality of marriage related to lower rates of depression for both men and women, although the overall rate for women was higher. For women with a good marital relationship, but for whom support from partner was not forthcoming at the time of the crisis (i.e. the person was "let down"), risk was increased, confirming a result from a study in Islington. The current study shows that the same set of findings holds for men. Gender differences did emerge when the subjective need for support within the marital relationship is taken into account, with women expressing greater need. However, such a desire for support was not necessarily translated into support-seeking behaviour as in a poor relationship turning to a partner was frequently inopportune. Women were also more likely to seek support outside the marriage; as in the earlier Islington research this was related to a lower risk of depression for those in a poor relationship. An unexpected finding was that men who received support outside marriage had an increased risk of depression.

Predicting depression in women: the role of past and present vulnerability.

BACKGROUND: A prospective study, covering just over a 1-year period, sought to confirm an earlier finding that around 40% of women who experience a severe life event in the presence of two ongoing psychosocial vulnerability factors, (negative close relationships and low self-esteem) will develop a major depressive episode. Distal risk factors were examined to see if they improved prediction. METHODS: A population sample of 105 mainly working-class mothers with vulnerability and without depression were interviewed three times over a 14-month period to date the occurrence of severe life events and onset of major depression. Degree of vulnerability was assessed at first contact together with distal risk in terms of childhood neglect/abuse and any earlier episodes of depression. RESULTS: Thirty-seven per cent of these vulnerable women became depressed in the study period. The majority experienced a severe life event, and of these, 48% had onsets. Contrary to expectation, risk was only a little less among those with just one of the two vulnerability factors. Two-thirds of women with an onset had been depressed in previous years. Although this was associated with increased risk, the effect was greatest for those who had experienced an episode before age 20. A relationship between childhood neglect/abuse and onset was entirely accounted for by such early depression. CONCLUSION: An aetiological model of depression outlined in earlier research was confined with a new factor of teenage depression shown to increase risk of onset.