Fat mass, weight and body shape changes at menopause - causes and consequences: a narrative review

In addition to age-related weight gain, menopause adds additional challenges for women with the occurrence of significant metabolic alterations and central and visceral fat redistribution. The changes in body composition then influence risks of cardiovascular disease, metabolic disruption, cancer, fracture, lung disease, sexual dysfunction, mental health disorders and dementia. They may also heighten the severity of vasomotor symptoms. Treatment of these changes requires a flexible long-term strategy. This narrative review explores the pathogenesis of the metabolic changes at menopause and effective management options.

Transitioning Behavioral Healthcare in Louisiana Through the COVID-19 Pandemic: Policy and Practice Innovations to Sustain Telehealth Expansion

A statewide COVID-19 quarantine order forced an abrupt shift for Louisiana’s behavioral health providers who provide mental health and substance abuse treatment services. The Center for Evidence to Practice conducted a study of this unprecedented shift to better understand the disruption and continuation of care during early statewide adoption of telemental health. The Center performed a mixed-method assessment including a series of focus groups and key informant interviews followed by a survey of over 300 responding providers. Over 85% of providers reported sustaining behavioral health services using a variety of telemental health strategies. While traditional referral networks and client volume were significantly disrupted, temporary relaxation of Medicaid regulatory and reimbursement policies appeared to be a key facilitator of telemental health adoption and continued services. Shifting to telemental health relied on provider’s quick adaptations, engaging clients with a hybrid of teleconferencing platforms, calls/texts, and socially-distanced in-person visits. Larger multi-clinician providers and evidence-based practice (EBP) providers were better equipped to support the adoption of telemental health. Rural and EBPs providers disproportionately discontinued services. Although many practitioners viewed the original COVID-19 pandemic as a short-lived condition, the recent emergence of Delta and other variants has shown the impact on the BH care system may be lasting. Flexibility across policies and a variety of telemental health platforms are keys to telehealth adaptation. However, the contraction of the client base raises concerns of increasing disparities among vulnerable and hard-to-reach populations if telemental health becomes a sustained approach in response to future COVID-19 variants.

Menopause status and climacteric symptoms in a birth cohort of mid-life New Zealand women

BACKGROUND

There is little current research on the transition to natural menopause among contemporary groups of mid-life women at age 40 years.

OBJECTIVE

This study reports on female members of the Christchurch Health and Development Study cohort. This research aimed to: document the menopause status, reproductive outcomes and climacteric symptoms of the women at age 40 years; examine the associations between menopause status and concurrent measures of psychosocial and economic well-being; and document the associations between menopause status and potential predictors of menopause reflecting childhood, family and individual factors prior to age 40 years.

METHODS

The Christchurch Health and Development Study is a longitudinal, representative, prospective cohort of 1265 babies (630 females) born in New Zealand in 1977. At age 40 years, 470 women (who had not experienced surgical menopause) were interviewed on their menopause status, climacteric symptoms and associated factors.

RESULTS

The majority of women were premenopausal, around 20% were perimenopausal and 2% were postmenopausal. Statistically significant associations were found reflecting higher rates of diagnosed reproductive disorder, climacteric symptoms, low occupational status, non-heterosexual sexuality and exposure to childhood sexual abuse amongst both perimenopausal and postmenopausal women at age 40 years.

CONCLUSION

These data will inform directions for future data collection and analyses.

Specialization Within a Specialty: Advanced Practice Psychiatric Nursing Pathways for the Greatest Good

Dr. Hildegard Peplau's theory on the primacy of the therapeutic interpersonal relationship remains central to the role of the psychiatric-mental health advanced practice nurse (PMH APN). In 1989, Peplau published her thoughts on how World War II (WWII) shaped early PMH APN practice. Following WWII and the return of hundreds of thousands of previously mentally healthy service members with combat-related psychiatric symptoms and disorders, the prevailing societal beliefs about mental illness began to shift from an innate/inherited etiological perspective to a broader appreciation of the additional contributions of social and environmental factors to mental well-being. With that awareness came a decrease in stigma and a shift from housing patients in psychiatric hospitals to treating them in community settings. The coronavirus 2019 (COVID-19) pandemic has likewise affected societal beliefs through exposure to the mental toll of massive infection rates, loss of life, social isolation, and other downstream consequences. During these times of crises, psychiatric nurses and educators are challenged to provide innovative solutions to meet the increased demands for psychosocial care. [Journal of Psychosocial Nursing and Mental Health Services, xx(xx), xx-xx.].

A 12-Week Evidence-Based Education Project to Reduce Cardiovascular and Metabolic Risk in Adults With Serious Mental Illness in the Integrated Care Setting

BACKGROUND: Individuals with serious mental illness (SMI) such as schizophrenia spectrum disorders, severe bipolar disorder, or severe recurrent major depressive disorder have a shorter life expectancy compared with those in the general population. This is largely due to the higher rates of diabetes, hyperlipidemia, and hypertension. Treatment adherence, diet, exercise, and weight management are modifiable risk factors for these cardiometabolic conditions, yet the use of educational lifestyle interventions is not common practice in the clinical setting. AIM: The purpose of this project was to evaluate a 12-week evidence-based diabetes prevention education program integrated into a primary care behavioral health setting for adults with SMI, diabetes, or prediabetes, and who were overweight or obese. METHOD: This project utilized a pretest-posttest intervention design. Outcomes for this project included diabetes knowledge, self-care, and health indicators (blood pressure, hemoglobin A1C, weight, body mass index, and medication adherence). The project also addressed feasibility and acceptability of the program in this setting. RESULTS: Project outcomes showed a reduction in weight, waist circumference, hemoglobin A1C, and blood pressure. Outcomes also indicated an improvement in participants' self-knowledge and self-care. CONCLUSIONS: There was a high attendance rate and overall acceptability and feasibility described by participants. This project highlights the important role that primary care providers can play in providing health education to patients with SMI.

Broadening the ecology of fear: non-lethal effects arise from diverse responses to predation and parasitism

Research on the 'ecology of fear' posits that defensive prey responses to avoid predation can cause non-lethal effects across ecological scales. Parasites also elicit defensive responses in hosts with associated non-lethal effects, which raises the longstanding, yet unresolved question of how non-lethal effects of parasites compare with those of predators. We developed a framework for systematically answering this question for all types of predator-prey and host-parasite systems. Our framework reveals likely differences in non-lethal effects not only between predators and parasites, but also between different types of predators and parasites. Trait responses should be strongest towards predators, parasitoids and parasitic castrators, but more numerous and perhaps more frequent for parasites than for predators. In a case study of larval amphibians, whose trait responses to both predators and parasites have been relatively well studied, existing data indicate that individuals generally respond more strongly and proactively to short-term predation risks than to parasitism. Apart from studies using amphibians, there have been few direct comparisons of responses to predation and parasitism, and none have incorporated responses to micropredators, parasitoids or parasitic castrators, or examined their long-term consequences. Addressing these and other data gaps highlighted by our framework can advance the field towards understanding how non-lethal effects impact prey/host population dynamics and shape food webs that contain multiple predator and parasite species.

Rural-urban disparities in the distribution of dental caries among children in south-eastern Louisiana: a cross-sectional study

INTRODUCTION

The purpose of this cross-sectional study was to assess the prevalence of dental caries among elementary school-aged children in rural compared to urban communities within south-eastern Louisiana that have participated in a school-based dental screening and sealant program.

METHODS

The authors utilized de-identified Sealant Efficiency Assessment for Locals and States screening data for 2007-2014 provided by The Health Enrichment Network oral health program. The screening was conducted throughout 46 elementary schools in Louisiana. Screening forms recorded decayed, missing, and filled permanent teeth (DMFT). Descriptive statistics including demographic characteristics and oral health conditions were calculated. Univariate and multivariable logistic regression analyses were performed to assess the burden of caries in schools.

RESULTS

Of 963 children screened, 32% had dental caries. There was an increased risk of having any DMFT among children who attended rural schools as compared to those who attended urban schools (prevalence odds ratio (POR)=2.17, 95% confidence interval (CI)=1.61-2.93). This study found that non-Hispanic black children had reduced odds of DMFT as compared to the children from other reported ethnicities (POR=0.695, 95%CI=0.503-0.960).

CONCLUSION

A higher prevalence of dental caries was found in rural compared to urban communities. Further research is needed to assess the extent of geographic differences to improve oral health outcomes.

Cytomegalovirus seropositivity is independently associated with cardiovascular disease in non-dialysis dependent chronic kidney disease

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of early death in patients with chronic kidney disease (CKD). Previous work has described an association between Cytomegalovirus (CMV) seropositivity and CVD amongst patients with dialysis dependent end stage renal disease. Whether CMV seropositivity is associated with CVD in non-dialysis dependent CKD has not been established.

AIM

Investigate whether past CMV infection is associated with prevalent CVD in patients with non-dialysis dependent CKD.

DESIGN

A retrospective observational study using the Renal Impairment in Secondary Care cohort, a study evaluating bio-clinical determinants of outcomes in patients with progressive CKD.

METHODS

We assayed cryopreserved serum samples collected at inception for anti-CMV IgG antibodies from 764 patients with stages 2 to 5 CKD (pre-dialysis) and investigated its relationship with prevalent CVD.

RESULTS

Median estimated glomerular filtration was 24 ml/min/1.73 m2 (IQR 19-32). Sixty-eight percent of patients were CMV seropositive. CMV seropositivity was associated with older age, non-Caucasian ethnicity, diabetes and higher social deprivation index score. On univariable analysis, CMV seropositivity correlated with higher systolic blood pressure (P = 0.044), prevalent CVD (P < 0.001), ischaemic heart disease (P < 0.001) and cerebrovascular disease (P = 0.022). On multivariable analysis, CMV seropositive patients nearly twice as likely to have CVD compared to seronegative patients [Odds Ratio (OR) = 1.998, CI 1.231-3.242, P = 0.005].

CONCLUSIONS

In patients with non-dialysis CKD, CMV seropositivity is independently associated with a higher prevalence of CVD.

Abstract PD8-07: Does resection of cavity shave margins result in lower positive margin and re-excision rates in patients with stage 0-III breast cancer? Results from a prospective multicenter randomized controlled trial

INTRODUCTION: Routine resection of cavity shave margins has been shown in single center studies to result in a significant reduction in positive margin and re-excision rates. In this prospective multicenter randomized controlled trial, we sought to validate these findings across practice settings.

METHODS: Nine centers across the United States, varying in practice setting and patient population, participated in this clinical trial of 398 stage 0-III breast cancer patients undergoing partial mastectomy (with or without resection of selective cavity margins). Participants were stratified by clinical stage and randomized 1:1 to either have routine cavity shave margins resected (“shave”) or not (“no shave”). Randomization group was revealed to the surgeon intraoperatively, after they had completed their standard partial mastectomy and were ready to close. Positive margins were defined as “tumor at ink” for invasive cancer or within 2 mm for ductal carcinoma in situ (DCIS). Adverse events were defined as seromas requiring percutaneous drainage, and/or hematomas or abscesses requiring operative intervention.

RESULTS: Median patient age was 65 (range; 29-94). 116 patients had invasive disease, 74 had DCIS, 179 had both, and 29 had no residual cancer at the time of partial mastectomy. The median invasive cancer size was 1.2 cm (range; 0.05-8.00 cm); the median extent of DCIS was 0.9 cm (range; 0.05-6.40 cm). The “shave” and “no shave” groups were well matched at baseline for clinicopathologic and demographic factors.

FactorShave (n=197)No Shave (n=201)p-valueAge (years); median (range)67 (36-94)64 (29-89)0.585Race  0.062-- White173 (87.8%)164 (81.6%) -- Black20 (10.2%)33 (16.4%) -- Asian2 (1.0%)2 (1.0%) -- Native American0 (0%)2 (1.0%) -- Unknown/Declined2 (1.0%)0 (0%) Hispanic ethnicity28 (14.2%)32 (15.9%)0.806Invasive tumor size (cm); median (range)1.30 (0.09-8.00)1.20 (0.05-7.50)0.282DCIS extent (cm); median (range)0.80 (0.10-6.40)1.00 (0.05-5.50)0.906Invasive histology  0.556-- Ductal177 (89.8%)186 (92.5%) -- Lobular16 (8.1%)13 (6.5%) -- Mucinous3 (1.5%)2 (1.0%) -- Other1 (0.5%)0 (0%) Neoadjuvant therapy15 (7.6%)19 (9.5%)0.592Palpable tumor57 (28.9%)56 (27.9%)0.825Node positive*24 (16.3%)16 (10.6%)0.175*Of the 298 patients who had lymph nodes evaluated

Prior to randomization, positive margin rates were similar in the “shave” and “no shave” groups (38.1% vs. 37.3%, respectively, p=0.918). After randomization, however, those in the “shave” group were significantly less likely than those in the “no shave” group to have positive margins (8.6% vs. 37.3%, respectively, p&lt;0.001). They were also less likely to require re-excision or mastectomy for margin clearance (8.6% vs. 23.9%, p&lt;0.001). There were no significant differences between the two groups in terms of adverse events (p=0.280). Rates of seroma (1.5% vs. 0.5%, p=0.368), hematoma (0.5% vs. 0.5%, p=1.000) and abscess (0.3% vs. 0%, p=0.495) were similar between the “shave” and “no shave” groups, respectively.

CONCLUSION: Resection of cavity shave margins significantly reduces positive margin and re-excision rates in patients with stage 0-III breast cancer undergoing partial mastectomy.

Citation Format: Chagpar AB, Tsangaris T, Garcia-Cantu C, Howard-McNatt M, Chiba A, Berger AC, Levine E, Gass JS, Gallagher K, Lum SS, Martinez RD, Willis AI, Pandya SV, Brown EA, Fenton A, Mendiola A, Murray M, Haddad V, Solomon NL, Senthil M, Bansil H, Ollila D, Snyder SK, Edmonson D, Lazar M, Namm JP, Li F, Butler M, McGowan NE, Herrera ME, Avitan YP, Yoder B, Dupont E. Does resection of cavity shave margins result in lower positive margin and re-excision rates in patients with stage 0-III breast cancer? Results from a prospective multicenter randomized controlled trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD8-07.

Prescription opioid use among individuals with serious mental illness

Prevalence and correlates of prescription opioid use were explored in individuals with serious mental illness (SMI) by examining a sample of adults from two inner city community psychiatry clinics. Of 271 participants, 12.9% (n = 35) were on a prescribed opioid. Being on an opioid was significantly associated with history of heroin use and active prescription sedative-hypnotic use, including benzodiazepine use. Concurrent use of opioids with sedative-hypnotics was significantly associated with suicidal ideation. The results highlight risks of prescription opioid use in those with SMI, particularly in combination with prescription sedative-hypnotics.

Infections on the move: how transient phases of host movement influence disease spread

Animal movement impacts the spread of human and wildlife diseases, and there is significant interest in understanding the role of migrations, biological invasions and other wildlife movements in spatial infection dynamics. However, the influence of processes acting on infections during transient phases of host movement is poorly understood. We propose a conceptual framework that explicitly considers infection dynamics during transient phases of host movement to better predict infection spread through spatial host networks. Accounting for host transient movement captures key processes that occur while hosts move between locations, which together determine the rate at which hosts spread infections through networks. We review theoretical and empirical studies of host movement and infection spread, highlighting the multiple factors that impact the infection status of hosts. We then outline characteristics of hosts, parasites and the environment that influence these dynamics. Recent technological advances provide disease ecologists unprecedented ability to track the fine-scale movement of organisms. These, in conjunction with experimental testing of the factors driving infection dynamics during host movement, can inform models of infection spread based on constituent biological processes.

Reported co-infection deaths are more common in early adulthood and among similar infections

BACKGROUND

Many people have multiple infections at the same time, but the combined contribution of those infections to disease-related mortality is unknown. Registered causes of death offer a unique opportunity to study associations between multiple infections.

METHODS

We analysed over 900,000 death certificates that reported infectious causes of death. We tested whether reports of multiple infections (i.e., co-infections) differed across individuals' age or sex. We also tested whether each pair of infections were reported together more or less often than expected by chance, and whether this co-reporting was associated with the number of biological characteristics they had in common.

RESULTS

In England and Wales, and the USA, 10 and 6 % respectively of infection-related deaths involved co-infection. Co-infection was reported reported most often in young adults; 30 % of infection-related deaths among those aged 25-44 from the USA, and 20 % of infection-related deaths among those aged 30-39 from England and Wales, reported multiple infections. The proportion of infection-related deaths involving co-infection declined with age more slowly in males than females, to less than 10 % among those aged >65. Most associated pairs of infections co-occurred more often than expected from their frequency of being reported alone (488/683 [71 %] in the USA, 129/233 [55 %] in England and Wales), and tended to share biological characteristics (taxonomy, transmission mode, tropism or timescale).

CONCLUSIONS

Age, sex, and biologically similar infections are associated with death from co-infection, and may help indicate patients at risk of severe co-infection.

Microleakage of Posterior Composite Restorations Lined with Self-adhesive Resin Cements

Two self-adhesive resin cements resulted in minimal microleakage scores when used as liners in Class II composite restorations.

Rates of very preterm birth in Europe and neonatal mortality rates

OBJECTIVE

To estimate the influence of variation in the rate of very preterm delivery on the reported rate of neonatal death in 10 European regions.

DESIGN

Comparison of 10 separate geographically defined European populations, from nine European countries, over a 1-year period (7 months in one region).

PARTICIPANTS

All births that occurred between 22(+0) and 31(+6) weeks of gestation in 2003.

MAIN OUTCOME MEASURE

Neonatal death rate adjusted for rate of delivery at this gestation.

RESULTS

Rate of delivery of all births at 22(+0)-31(+6) weeks of gestation and live births only were calculated for each region. Two regions had significantly higher rates of very preterm delivery per 1000 births: Trent UK (16.8, 95% CI 15.7 to 17.9) and Northern UK (17.1, 95% CI 15.6 to 18.6); group mean 13.2 (95% CI 12.9 to 13.5). Four regions had rates significantly below the group average: Portugal North (10.7, 95% CI 9.6 to 11.8), Eastern and Central Netherlands (10.6, 95% CI 9.7 to 11.6), Eastern Denmark (11.2, 95% CI 10.1 to 12.4) and Lazio in Italy (11.0, 95% CI 10.1 to 11.9). Similar trends were seen in live birth data. Published rates of neonatal death for each region were then adjusted by applying (a) a standardised rate of very preterm delivery and (b) the existing death rate for babies born at this gestation in the individual region. This produced much greater homogeneity in terms of neonatal mortality.

CONCLUSIONS

Variation in the rate of very preterm delivery has a major influence on reported neonatal death rates.

The impact of parasite dispersal on antagonistic host-parasite coevolution

Coevolving populations of hosts and parasites are often subdivided into a set of patches connected by dispersal. Higher relative rates of parasite compared with host dispersal are expected to lead to parasite local adaptation. However, we know of no studies that have considered the implications of higher relative rates of parasite dispersal for other aspects of the coevolutionary process, such as the rate of coevolution and extent of evolutionary escalation of resistance and infectivity traits. We investigated the effect of phage dispersal on coevolution in experimental metapopulations of the bacterium Pseudomonas fluorescens SBW25 and its viral parasite, phage SBW25Phi2. Both the rate of coevolution and the breadth of evolved infectivity and resistance ranges peaked at intermediate rates of parasite dispersal. These results suggest that parasite dispersal can enhance the evolutionary potential of parasites through provision of novel genetic variation, but that high rates of parasite dispersal can impede the evolution of parasites by homogenizing genetic variation between patches, thereby constraining coevolution.

Squamous cell carcinoma arising in a dermoid cyst of the ovary: a case series

OBJECTIVE

Malignant transformation in a dermoid cyst of the ovary is a rare complication, occurring in only 1-2% of cases, with squamous cell carcinoma being the most common type. Preoperative diagnosis is difficult because of the lack of specific symptoms and signs to suggest malignancy. Because of the small numbers of women involved, our knowledge of this rare tumour type is limited. This study aims to further characterise the population of women affected, the disease itself and the most appropriate management strategy.

DESIGN

We identified 14 women with this diagnosis between 1989 and 2006. This is a descriptive study, looking at the patient characteristics, mode of presentation and the role of tumour markers and radiological imaging in diagnosis. We also examined the stage and pathological features of the tumour at presentation and the subsequent course of the disease. We have also described our experiences using surgery, chemotherapy and radiotherapy in the management of these women.

RESULTS

We found that these tumours present at an age older than that of mature teratomas and that there are no reliable diagnostic tools or prognostic indicators. The behaviour of these tumours is unpredictable, and the role of chemotherapy and radiotherapy remains unclear. We suggest that repeated surgical resection of disease at the time of relapse could give a very durable response in selected women.

THE IMPACT OF PARASITE MANIPULATION AND PREDATOR FORAGING BEHAVIOR ON PREDATOR–PREY COMMUNITIES

Parasites are known to directly affect their hosts at both the individual and population level. However, little is known about their more subtle, indirect effects and how these may affect population and community dynamics. In particular, trophically transmitted parasites may manipulate the behavior of intermediate hosts, fundamentally altering the pattern of contact between these individuals and their predators. Here, we develop a suite of population dynamic models to explore the impact of such behavioral modifications on the dynamics and structure of the predator-prey community. We show that, although such manipulations do not directly affect the persistence of the predator and prey populations, they can greatly alter the quantitative dynamics of the community, potentially resulting in high amplitude oscillations in abundance. We show that the precise impact of host manipulation depends greatly on the predator's functional response, which describes the predator's foraging efficiency under changing prey availabilities. Even if the parasite is rarely observed within the prey population, such manipulations extend beyond the direct impact on the intermediate host to affect the foraging success of the predator, with profound implications for the structure and stability of the predator-prey community.

Pathogen responses to host immunity: the impact of time delays and memory on the evolution of virulence

Current analytical models of the mammalian immune system typically assume a specialist predator-prey relationship between invading pathogens and the active components of the immune response. However, in reality, the specific immune system is not immediately effective following invasion by a novel pathogen. First, there may be an explicit time delay between infection and immune initiation and, second, there may be a gradual build-up in immune efficacy (for instance, during the period of B-cell affinity maturation) during which the immune response develops, before reaching maximal specificity to the pathogen. Here, we use a novel theoretical approach to show that these processes, together with the presence of long-lived immune memory, decouple the immune response from current pathogen levels, greatly changing the dynamics of the pathogen-immune system interaction and the ability of the immune response to eliminate the pathogen. Furthermore, we use this model to show how distributed primary immune responses combine with immune memory to greatly affect the optimal virulence of the pathogen, potentially resulting in the evolution of highly virulent pathogens.

The relationship between polychlorinated biphenyls in blubber and levels of nematode infestations in harbour porpoises, Phocoena phocoena

Post-mortem examinations of harbour porpoises, Phocoena phocoena, regularly reveal heavy parasitic worm burdens. These same post-mortem records show varying levels of polychlorinated biphenyls (PCBs) accumulating in the blubber of porpoises. Although a number of papers have documented geospatial and temporal changes of PCBs and their detrimental effects on marine mammal health, as yet none have examined their role in determining nematode burdens in wild marine mammal populations. Using a data set consisting of harbour porpoises stranded in the UK between 1989 and 2002, we found a significant, positive association between PCB levels and nematode burdens, although the nature of the relationship was confounded with porpoise sex, age and cause of death. It was also apparent that individuals with the heaviest infestations of nematodes did not have the highest PCB level: while PCBs are important, they are clearly not the sole determinants of nematode burdens in wild populations of the harbour porpoise around the UK.

Patterns of parasite aggregation in the wild European rabbit (Oryctolagus cuniculus)

Understanding the factors controlling the distribution of parasites within their host population is fundamental to the wider understanding of parasite epidemiology and ecology. To explore changes in parasite aggregation, Taylor's power law was used to examine the distributions of five gut helminths of the wild rabbit. Aggregation was found to be a dynamic process that varied with year, season, host sex, age class, and myxomatosis. Yearly and seasonal changes are thought, in the main, to be the result of variations in weather conditions acting upon infectious stages (or intermediate hosts). Evidence in support of this was the comparatively low degree of fluctuation in the aggregation of the pinworm, Passalurus ambiguus, as the infectious stage of this parasite is likely to be less susceptible to environmental variation. Host age had a marked effect on the level of aggregation of all parasites, but this effect varied between parasite species. P. ambiguus, Trichostrongylus retortaeformis and Cittotaenia denticulata aggregation were lower in adult than juvenile rabbits whilst Graphidium strigosum and Mosgovoyia pectinata aggregation tended to increase with age. Host immunity is thought to be responsible for these differences. Differences in aggregation for different parasites were also seen when the rabbit population was split into males and females. Myxomatosis had a marked effect on helminth distribution with substantially less aggregation in rabbits showing clinical signs of the disease.

Passive and active place avoidance as a tool of spatial memory research in rats

A modified model of the arena described by Bures et al. (Bures J, Fenton AA, Kaminsky Y, Zinyuk L. Place cells and place navigation, Proc. Natl. Acad. Sci. USA. 1997a;94:343-350) was applied to the place learning of adult male rats in two different avoidance paradigms. In the passive avoidance task rats exploring a stationary circular arena had to avoid a 60 degrees sector entering of which was punished by mild footshocks. Intramaze as well as extramaze cues could be used for adequate solution of this task. In the active avoidance paradigm rats were trained to avoid a room frame defined sector (e.g. North-East) of a slowly rotating arena the movement of which forced the animals to rely on extramaze cues and to ignore intramaze information. Rats had to find an active solution of the task since otherwise they were passively transported into the room frame defined punished zone. The suitability of these tasks for testing spatial abilities of rats is discussed.

Re-assessing the infection strategies of the entomopathogenic nematode Steinernema feltiae (Rhabditidae; Steinernematidae)

Previous studies have indicated that between 60 and 80% of a population of entomopathogenic nematodes do not infect their insect hosts at any one period in time. Two hypotheses explain this behaviour: the first that there is a subpopulation of non-infectious nematodes and the second that the non-infectious group is created by inhibitory cues derived from infected insects. Through an experimental approach with the Galleria mellonella-Steinernema feltiae system we show that both mechanisms operate together. When conditions for infection were optimized, the sum of individual infection behaviours was similar to the number infecting as a population, implying observed infection rates are driven by intrinsic mechanisms. In addition, there was evidence that an infected host released a chemical cue into the environment which inhibited subsequent levels of infection. This degree of inhibition was independent of the number of infecting nematodes. Both these mechanisms are dynamic, so the observed proportion of infectious nematodes depended heavily on the time of exposure. The implications of these findings for both the design of laboratory trials and the use of entomopathogenic nematodes in biological control are discussed.

A regulatory RNA (PrrB RNA) modulates expression of secondary metabolite genes in Pseudomonas fluorescens F113

The GacS-GacA two-component signal transduction system, which is highly conserved in gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in Pseudomonas spp. Screening of a Pseudomonas fluorescens F113 gene bank led to the isolation of a previously undefined locus which could restore secondary metabolite production to both gacS and gacA mutants of F113. Sequence analysis of this locus demonstrated that it did not contain any obvious Pseudomonas protein-coding open reading frames or homologues within available databases. Northern analysis indicated that the locus encodes an RNA (PrrB RNA) which is able to phenotypically complement gacS and gacA mutants and is itself regulated by the GacS-GacA two-component signal transduction system. Primer extension analysis of the 132-base transcript identified the transcription start site located downstream of a sigma(70) promoter sequence from positions -10 to -35. Inactivation of the prrB gene in F113 resulted in a significant reduction of 2, 4-diacetylphloroglucinol (Phl) and hydrogen cyanide (HCN) production, while increased metabolite production was observed when prrB was overexpressed. The prrB gene sequence contains a number of imperfect repeats of the consensus sequence 5'-AGGA-3', and sequence analysis predicted a complex secondary structure featuring multiple putative stem-loops with the consensus sequences predominantly positioned at the single-stranded regions at the ends of the stem-loops. This structure is similar to the CsrB and RsmB regulatory RNAs in Escherichia coli and Erwinia carotovora, respectively. Results suggest that a regulatory RNA molecule is involved in GacA-GacS-mediated regulation of Phl and HCN production in P. fluorescens F113.

The effects of oviposition aggregation on the incidence of sheep blowfly strike

The distribution of a parasite population within its natural host population can have a significant influence on the dynamics of both the host and parasite populations. The majority of parasite species are typically distributed in an aggregated manner within the host population, leaving most hosts lightly infected and a few hosts supporting very large parasite burdens. This paper presents a consideration of the effects of aggregation on the incidence of ovine cutaneous myiasis caused by the sheep blowfly, Lucilia sericata (Meigen). Using simulation analysis, the mechanisms causing larval aggregation are included in the model, allowing the consequences for control to be investigated. By explicitly incorporating host susceptibility, it becomes apparent that early in the season, strategies targeting the blowfly population may prove more effective in suppressing strike levels, whereas later in the season, treatment of the sheep population may be more beneficial. The analysis also shows that the greater the degree of aggregation, the fewer sheep that become struck and, hence, suggests that increasing the heterogeneity in susceptibility amongst a flock of sheep restricts strikes to relatively few sheep. Providing the highly-susceptible sheep could be identified, concentrating strikes on a low number of sheep would allow fewer sheep to be treated, leading to a more efficient means of controlling the blowfly population and suppressing strike.

The effect of farm management strategies on the incidence of sheep strike in Britain: a simulation analysis

A deterministic model is used to simulate the seasonal incidence of sheep myiasis (strike) on farms in Britain and to explore the effects of different farm management strategies on strike incidence. The model is based on two sub-components: the seasonal pattern of abundance of the primary agent of sheep myiasis in northwest Europe, the blowfly Lucilia sericata and the range of factors known to influence ewe and lamb susceptibility to strike. The results of these simulations show that familiar farm management strategies, such as shearing, reduction in scouring caused by endoparasitic worms and insecticide use can have an important role in the reduction of strike incidence in ewes and lambs. However, the effectiveness of these techniques can be highly dependent of their timing in relation to seasonal changes in blowfly abundance and the effects of temperature and rainfall.

The incidence of sheep strike by Lucilia sericata on sheep farms in Britain: a simulation model

Using a combination of a temperature-dependent simulation of the population dynamics of Lucilia sericata and a logistic model of sheep susceptibility, based on patterns of faecal soiling, fleece length and fleece humidity, a deterministic simulation model has been constructed to predict the incidence of sheep strike by L. sericata on lambs and ewes in Britain. Strikes are assigned to individual sheep in the flock according to a negative binomial distribution. The model shows that the majority of the first strikes of the season occur equally on ewes and lambs, when ewe fleeces are long and before lamb susceptibility increases though faecal soiling. With each subsequent generation of gravid blowflies, however, a greater proportion of strikes occur on lambs, while the number of strikes observed on ewes remains relatively consistent throughout the season. The increase in strike of lambs is due to the seasonal increase in lamb faecal soiling, associated with rising helminth infections and lamb fleece growth. The model shows that at the beginning of the season the incidence of strike is limited by the low number of flies present: towards the end of seasons, however, the blowfly population had grown large enough for the number of strikes to be limited by the number of susceptible ewes and lambs. The model shows that the seasonal incidence of strike is highly sensitive to the interactions between temperature, rainfall and would length. Strike was most prevalent under warm, wet conditions. However, there is a critical period during spring, where the short fleeces of lambs and ewes, in the latter case due to shearing, results in the desiccation of egg batches. If this coincides with dry conditions, the high levels of mortality result in suppression of the fly population and a reduction in the subsequent incidence of strike.

Role of 2,4-Diacetylphloroglucinol in the Interactions of the Biocontrol Pseudomonad Strain F113 with the Potato Cyst Nematode Globodera rostochiensis

The potato cyst nematode Globodera rostochiensis is an important pest of potato (Solanum tuberosum). Pseudomonas fluorescens F113, which produces 2,4-diacetylphloroglucinol (DAPG), was investigated as a potential biocontrol agent against G. rostochiensis. Exposure of nematode cysts to the pseudomonad, under in vitro conditions or in soil microcosms, almost doubled the ability of the eggs to hatch. The percentage of mobile juveniles was reduced threefold following their incubation in the presence of the pseudomonad, both in vitro and in soil. Results obtained with a transposon-induced DAPG-negative biosynthetic mutant of F113 and its complemented derivative with restored DAPG synthesis showed that the ability of strain F113 to produce DAPG was responsible for the increase in hatch ability and the reduction in juvenile mobility. Similar effects on egg hatch ability and juvenile mobility of G. rostochiensis were obtained in vitro by incubating nematode cysts and juveniles, respectively, in the presence of synthetic DAPG. DAPG-producing P. fluorescens F113 is proposed as a potential biocontrol inoculant for the protection of potato crops against the potato cyst nematode.