bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of matrix metalloproteinase‐9 in mononuclear cells of hyperhomocysteinaemic subjects
Authors: Holven K. B. , Halvorsen B. , Schulz H. , Aukrust P. , Ose L. , Nenseter M. S.
Published: June 2003

Atherosclerotic plaque instability and rupture requires extracellular matrix modification, a complex process regulated by matrix metalloproteinases (MMPs). We hypothesized that homocysteine's atherogenic effects may involve MMP‐mediated mechanisms. Our results showed the following: (i) Compared with healthy control subjects (n = 9), patients with hyperhomocysteinaemia (n = 9) had elevated mRNA levels of MMP‐9 and tissue inhibitors of metalloproteinases‐1 (TIMP‐1) in freshly isolated peripheral blood mononuclear cells (PBMCs), which were positively correlated with homocysteine and negatively correlated with folate and vitamin B12 levels. (ii) Peripheral blood mononuclear cells obtained from these patients released markedly enhanced the amount of MMP‐9 upon oxidized LDL (oxLDL) stimulation, whereas no such enhancing effect was seen in cells from healthy controls. (iii) During folic acid 6 weeks’ treatment, normalization of homocysteine levels was accompanied by a significant reduction in mRNA levels of MMP‐9 and TIMP‐1 in PBMCs, as well as a marked reduction in oxLDL‐stimulated release of MMP enzyme activity. These novel findings may suggest that homocysteine exerts its atherogenic effect in part by elevating levels and activity of MMPs, which in turn may enhance matrix degradation, potentially promoting atherogenesis and plaque instability. Moreover, our findings suggest that folic acid supplementation may down‐regulate these inappropriate responses in these patients.
Alternative sources of beta cells for cell therapy of diabetes
Authors: Scharfmann R.
Published: June 2003

Type 1 and type 2 diabetes affect 150 million people worldwide. This is a result of the incapacity of pancreatic beta cells to produce and secrete enough insulin. Transplantation of pancreatic beta cells represents a potential therapeutic approach for type 1 diabetes. However, one limitation is the insufficient amount of beta cells available for grafts. Alternative sources of beta cells have yet to be defined. During the past years, progress has been made in the definition of new strategies to produce mature pancreatic beta cells. Different cell sources are currently tested for their capacity to differentiate into mature beta cells. In this review, I will summarize the status of our knowledge in the field of cell therapy for diabetes.
Coupled biogeochemical and hydrological responses of streams and rivers to drought
Authors: Dahm Clifford N. , Baker Michelle A. , Moore Douglas I. , Thibault James R.
Published: June 2003

Severe or extreme droughts occurred about 10% of the time over a 105‐year record from central New Mexico, U.S.A., based on the Palmer Drought Severity Index.

Drought lowers water tables, creating extensive areas of groundwater recharge and fragmenting reaches of streams and rivers. Deeper groundwater inputs predominate as sources of surface flows during drought. Nutrient inputs to streams and rivers reflect the biogeochemistry of regional ground waters with longer subsurface residence times.

Inputs of bioavailable dissolved organic carbon to surface waters decrease during drought, with labile carbon limitation of microbial metabolism a byproduct of drought conditions.

Decreased inputs of organic forms of carbon, nitrogen and phosphorus and a decrease in the organic : inorganic ratio of nutrient inputs favours autotrophs over heterotrophs during drought.

The fate of autotrophic production during drought will be strongly influenced by the structure of the aquatic food web within impacted sites.
Parallels and contrasts in the effects of drought on stream macroinvertebrate assemblages
Authors: Boulton Andrew J.
Published: June 2003

It is axiomatic that unusually long dry periods (droughts) adversely affect aquatic biota. Recovery after drought is rapid by macroinvertebrates that possess strategies to survive drying or are highly mobile but other taxa take longer to recolonise depending on the timing, intensity, and duration of the dry phase.

Although drought acts as a sustained ‘ramp’ disturbance, impacts may be disproportionately severe when certain critical thresholds are exceeded. For example, ecological changes may be gradual while a riffle dries but cessation of flow causes abrupt loss of a specific habitat, alteration of physicochemical conditions in pools downstream, and fragmentation of the river ecosystem. Many ecological responses to drought within these habitats apparently depend on the timing and rapidity of hydrological transitions across these thresholds, exhibiting a ‘stepped’ response alternating between gradual change while a threshold is approached followed by a swift transition when a habitat disappears or is fragmented.

In two Australian intermittent streams, drought conditions eliminated or decimated several groups of macroinvertebrates, including atyid shrimps, stoneflies and free‐living caddisflies. These taxa persisted during the early stages of the drought but did not recruit successfully the following year, despite a return to higher‐than‐baseflow conditions. This ‘lag effect’ in response to drought emphasises the value of long‐term survey data. Although changes in faunal composition were inconsistent among sites, marked shifts in taxa richness, abundance and trophic organisation after the riffle habitat dried provide evidence for a stepped response.

Responses by macroinvertebrate assemblages to droughts of differing severity in English chalk streams were variable. The prolonged 1988–92 drought had a greater impact than shorter droughts in the early 1970s but recovery over the next 3 years was swift. Effects of the 1995 summer drought were buffered by sustained groundwater discharge from the previous winter. These droughts tended to reduce available riverine habitats, especially via siltation, but few taxa were eliminated because they could recolonise from perennial sections of the chalk streams.

In the contrasting environments of the intermittent streams studied in England and Australia, there are parallels in the rapid rates of recolonisation. However, recruitment by taxa that lack desiccation‐resistant stages or have limited mobility is delayed. Currently, long‐term data on these systems may be insufficient to indicate persistent effects of droughts or predict the impacts of excessive surface or groundwater abstraction or the increased frequency and duration of droughts expected with global climate change.
Causes and consequences of long‐term climatic variability on the Australian continent
Authors: Kershaw Peter , Moss Patrick , Van Der Kaars Sander
Published: June 2003

Summary 1. Ice‐volume forced glacial–interglacial cyclicity is the major cause of global climate variation within the late Quaternary period. Within the Australian region, this variation is expressed predominantly as oscillations in moisture availability. Glacial periods were substantially drier than today with restricted distribution of mesic plant communities, shallow or ephemeral water bodies and extensive aeolian dune activity.

2. Superimposed on this cyclicity in Australia is a trend towards drier and/or more variable climates within the last 350 000 years. This trend may have been initiated by changes in atmospheric and ocean circulation resulting from Australia's continued movement into the Southeast Asian region and involving the onset or intensification of the El Niño‐Southern Oscillation system and a reduction in summer monsoon activity.

3. Increased biomass burning, stemming originally from increased climatic variability and later enhanced by activities of indigenous people, resulted in a more open and sclerophyllous vegetation, increased salinity and a further reduction in water availability.

4. Past records combined with recent observations suggest that the degree of environmental variability will increase and the drying trend will be enhanced in the foreseeable future, regardless of the extent or nature of human intervention.
Effects of drought on fish across axes of space, time and ecological complexity
Authors: Matthews William J. , Marsh‐Matthews Edie
Published: June 2003

We evaluate the position of 50 previously published studies of fish and drought with respect to spatial scale of study (individual stream pools to subcontinents), length of the dry period (weeks to centuries), and level of system complexity (individual fish to ecosystems). Most papers address short (months to a year) droughts or dry periods, in local reaches of streams, and impacts on populations or local assemblages. In these 50 papers, the most frequently demonstrated effects of drought were population declines, loss of habitat, changes in the community, negative effects from changes in water quality, movement within catchments, and crowding of fish in reduced microhabitats. Thirteen other less frequent effects also were identified.

Gaps in knowledge exist on effects of long‐term droughts (decades to centuries), influence of drought on fish effects in ecosystems, and at the spatial scale of river basins to subcontinents. However, some of these gaps have recently been addressed, particularly additive effects of repeated drying episodes and whole‐lake or basin‐wide effects of drought, and in using molecular techniques to seek signals of drought at wide geographic scales because of events in the deep past. Gaps in knowledge remain for effects of very short dry periods, on drought effects on higher levels of complexity, and on the manner in which droughts at the scale of decades affect fish.

Data from streams in Oklahoma and elsewhere in the south‐western U.S.A. suggest that most droughts may leave little persistent signal in the existing fish fauna, i.e. that recovery from drought by fish populations or assemblages in the region can be rapid. However, species that are vulnerable to drought or water loss in streams may have disappeared from some basins in the region before the mid‐1900s, and recent evidence also suggests that extreme droughts do sometimes alter fish assemblages.

Little is known about mechanisms by which droughts have direct or indirect effects on fish, the roles of droughts in the evolution of fish species, and the ways droughts alter effects of fish in ecosystems. Global climate changes may have serious consequences for future local or regional fish faunas, but ongoing studies of fish experiencing drought may aid in future conservation of what will become species at risk under climate‐change scenarios.
The role of refugia for fishes during drought: a review and synthesis
Authors: Magoulick Daniel D. , Kobza Robert M.
Published: June 2003

Drought is a natural disturbance of aquatic ecosystems and can be a major factor in structuring aquatic communities. For individuals, populations and communities to persist in disturbed environments, they must have refuge from disturbance or disturbance must be minimal. Refugia convey spatial and temporal resistance or resilience in the face of disturbance, but the role of refugia in aquatic systems remains poorly understood.

2. We review available literature on aquatic refugia for fishes in order to synthesise current knowledge and provide suggestions for needed research. Our objectives were to clarify definitions of disturbance and refugia in the context of drought in aquatic systems, review how refuge habitats influence fish community structure, and consider the potential impact of refugia on fish population and community dynamics during drought.

3. Droughts cause a decrease in surface area/volume and an increase in extremes of physical and chemical water quality parameters. These conditions are linked with biotic interactions that structure the community of fishes residing in low‐flow or dry season refugia by increasing mortality rates, decreasing birth rates and/or increasing migration rates. Many aquatic organisms seek refuge from disturbance and/or have adaptations (e.g. physiological tolerance) that provide refuge.

4. Drought in aquatic systems leads to shifts in refugia spacing and connectance at multiple spatial and temporal scales. Refuge size, disturbance intensity, and mobility of organisms is predicted to play a large role in population persistence. We expect that refuge habitats will experience net immigration during drying and net emigration after rewetting, with the opposite occurring in surrounding habitat patches. Population dynamics of fishes using refugia during drought are best modelled by modified source‐sink dynamics, but dynamics are likely to change with spatial scale.
Drought and aquatic ecosystems: an introduction
Authors: Humphries Paul , Baldwin Darren S.
Published: June 2003

1. This paper introduces, and summarises the key messages of, a series of papers that emanated from a symposium on the Role of Drought in the Ecology of Aquatic Systems, held in Australia in 2001.

2. Defining drought hydrologically is problematic because the return times, intensity, duration and long‐term trends in low‐flow periods are specific to regions and times. Droughts may instead be referred to as ‘significant low‐flow periods’, many of which have been replaced by ‘anti‐drought’ conditions in rivers as they are used increasingly as irrigation conduits.

3. Droughts can be divided into those that cause predictable, seasonal press disturbances and less predictable, protracted ‘ramp’ disturbances. However, while droughts may be ‘ramp’ disturbances, their effects on aquatic biota are most likely to be ‘stepped’ when geomorphological or hydrological thresholds are crossed, causing abrupt changes in biological community structure and ecosystem processes.

4. Physical, morphological, physiological or behavioural refugia confer resistance or resilience to riverine populations and communities that experience drought conditions. The physical and chemical parameters associated with refugia habitats and their formation, influence population parameters within, and interactions among, species and can have protracted reproductive consequences, even well after the cessation of the drought.

5. Fish, invertebrate and plant populations and assemblages seem to recover rapidly from drought. Most studies of the effects of drought, however, have arisen fortuitously and have involved relatively short temporal, and small spatial, scales. Innovative approaches, such as microsatellite DNA analyses, can reveal that the effects of drought may be profound and long‐lasting, resulting in population bottlenecks and altering the course of the evolution of species.

6. During periods of drought, decreases in inputs of dissolved organic carbon, nitrogen and phosphorus may lead to carbon limitation to microbial metabolism, resulting in autotrophic production being favoured over heterotrophic production.

7. Long‐term climate trends, as indicated by palaeoecological evidence, suggest that, at least for Australia, droughts are likely to occur more frequently in the future. Anthropogenic effects on climate are likely to exacerbate this.

8. It is important that drought is seen for what it is: a natural extreme of the flow continuum, with flooding at the other extreme. Thus, despite the potential for dramatic impacts on aquatic biota and the negative social connotations associated with such events, drought must be incorporated into river management plans.
Effects of extreme low flows on freshwater shrimps in a perennial tropical stream
Authors: Covich A.P. , Crowl T.A. , Scatena F.N.
Published: June 2003

Long‐term data on rainfall suggests that perennial rainforest streams rarely are subject to drying of riffles or pools in the wet, non‐seasonal Caribbean climate of Puerto Rico. Unusually low rainfall in 1994 caused some headwater riffles to dry out completely, resulting in isolated pools, reduced pool volumes and loss of access to microhabitats by benthic invertebrates.

From 1992 to 1998, shrimp populations were sampled bimonthly using baited traps in six pools along 1200 m (from 305 to 480 m in altitude) of Quebrada Prieta, a second‐order headwater stream in the Luquillo Experimental Forest (Caribbean National Forest).

Following contraction of the smaller and shallower pools in the most upstream section of the stream, mean densities of the dominant shrimp (Atya lanipes) increased from 22 to 75 shrimp m−2 of pool area during the 1994 drought year. A second common species (Xiphocaris elongata) increased from 5 to 14 shrimp m−2. A smaller percentage of adults of both species was gravid during the drought.

Following the 1994 drought (1995–1998), densities of both shrimp species and reproductive activity of Atya returned to predrought (1990–1993) levels. However, the reproductive activity of Xiphocaris remained lower than in the predrought period.

It is suggested that prolonged droughts, even in tropical rainforest biomes, may significantly alter aquatic communities through localised crowding effects resulting from habitat contraction, and lead to prolonged decreases in reproductive output. Consequently, major alterations in aquatic populations and communities would be predicted by current climate change scenarios of decreased total rainfall and increased variability.
Why organizations adopt information system process innovations: a longitudinal study using Diffusion of Innovation theory
Authors: Mustonen‐Ollila Erja , Lyytinen Kalle
Published: June 2003

Abstract.  This paper identifies factors that affected over 200 information system (IS) process innovation adoption decisions in three organizational environments over a period that spanned four decades. The analysis is based on Rogers's (1995) theory of Diffusion of Innovations (DOI). The results show that several DOI factors strongly affect IS process innovation adoption. These include user need recognition, availability of technological infrastructure, past experience, own trials, autonomous work, ease of use, learning by doing and standards. Yet, a large number of IS process innovation adoptions followed no discernible pattern.
The paucity of multimethod research: a review of the information systems literature
Authors: Mingers John
Published: June 2003

Abstract.  It has commonly been argued that the use of different research methods within the information system (IS) discipline and within individual pieces of research will produce richer and more reliable results. This paper reports on a survey of the IS literature to discover the extent of multimethod research. The findings are that such work is relatively scarce, and where it occurs involves only a small set of traditional methods. Possible reasons for this are discussed.
Protection against atypical furunculosis in Atlantic halibut, Hippoglossus hippoglossus (L.); comparison of a commercial furunculosis vaccine and an autogenous vaccine
Authors: Gudmundsdóttir S , Lange S , Magnadóttir B , Gudmundsdóttir B K
Published: June 2003

Atlantic halibut, Hippoglossus hippoglossus (L.), was shown to be sensitive to infection by three different isolates of Aeromonas salmonicida ssp. achromogenes in pre‐challenge tests using intraperitoneal (i.p.) and intramuscular (i.m.) injections as well as bath challenges. A commercial furunculosis vaccine, Alphaject 1200, and an autogenous vaccine, AAS, based on the challenge strain, induced immune protection as shown in challenge tests 8 weeks post‐immunization. The survival rate of vaccinated fish after i.p. challenge was 100%, whereas mortality of control fish was 61%. Employing i.m. challenge, relative percentage survival induced by the furunculosis vaccine and the AAS vaccine was 47 and 44, respectively. Mortality of i.m. injected controls was 68%. Vaccinated fish behaved normally following vaccination but the weight gain was significantly reduced in vaccinated fish 8 weeks post‐vaccination compared with control fish receiving phosphate‐buffered saline. At the same time, intra‐abdominal adhesions were observed in fish injected with either of the two vaccines or adjuvant alone. Antibody response against A. salmonicida ssp. achromogenes was detected in sera from fish receiving either vaccine.
Non‐specific immune response of turbot, Scophthalmus maximus (L.), experimentally infected with a pathogenic Vibrio pelagius
Authors: Villamil L , Figueras A , Aranguren R , Novoa B
Published: June 2003

The effect of a pathogenic Vibrio pelagius, isolated during a mass mortality of turbot larvae, on the non‐specific immune response of turbot, Scophthalmus maximus (L.), macrophages was studied both in vitro and in vivo. The in vitro treatment of head kidney (HK) macrophages with viable V. pelagius caused a significant inhibition of the chemiluminescence (CL) response in comparison with untreated macrophages, while incubation with heat‐killed bacteria did not affect this response. In vivo, the intraperitoneal injection of V. pelagius resulted in a significant inhibition of the CL response in infected fish at days 1 and 4 post‐infection compared with the control fish response. The HK macrophage nitric oxide (NO) production was enhanced by in vitro incubation with intermediate doses of viable V. pelagius (5 × 103 and 5 × 104 bacteria mL−1) and higher doses of the heat‐killed bacteria (5 × 104–5 × 106 bacteria mL−1). In both cases, the NO inhibitorN‐ω ‐nitro‐L‐arginine was capable of down‐regulating the specific NO induction caused by incubation with the bacterial treatments. In contrast, incubation with ECPs at higher doses caused a reduction in NO production.

In vivo, a significant enhancement in NO production was also observed in macrophage supernatants at day 10 post‐infection. Lysozyme concentration in the serum was also significantly increased in the experimentally infected fish at days 4 and 10 post‐injection. In addition, viable V. pelagius and its ECPs significantly reduced HK macrophage viability in vitro, whereas no significant differences in viability were observed during the incubation with heat‐killed bacteria. As NO production was enhanced in the experimentally infected fish, the inhibitory effect of the NO donor, S‐nitroso‐acetyl‐penicillamine (SNAP), was tested in vitro in a cell‐free assay. The results showed that growth of V. pelagius was significantly inhibited using SNAP at a high concentration (1 mm).
A single‐dose pharmacokinetic study of oxolinic acid and vetoquinol, an oxolinic acid ester, in cod, Gadus morhua L., held in sea water at 8 °C and in vitro antibacterial activity of oxolinic acid against Vibrio anguillarum strains isolated from diseased cod
Authors: Samuelsen O B , Bergh Ø , Ervik A
Published: June 2003

The pharmacokinetic properties of the antibacterial agent oxolinic acid and vetoquinol, the carbitol ester of oxolinic acid, were studied after intravenous (i.v.) and oral (p.o.) administration to 100–150 g cod, Gadus morhua L., held in sea water at 8 °C. Following i.v. injection, the plasma drug concentration‐time profile showed two distinct phases. The distribution half‐life (t1/2α) was estimated at 1.3 h, the elimination half‐life (t1/2β) as 84 h and the total body clearance (ClT) as 0.047 L kg−1 h−1. The volume of distribution at steady state, Vd(ss) was calculated to be 5.5 L kg−1, indicating good tissue penetration of oxolinic acid in cod. Following p.o. administration of oxolinic acid or vetoquinol, the peak plasma concentrations (Cmax) of oxolinic acid and the time to peak plasma concentrations (Tmax) were estimated to be 1.2 and 2.5 μg mL−1, and 24 and 12 h, respectively. The bioavailabilities of oxolinic acid following p.o. administration of oxolinic acid and vetoquinol were calculated to be 55 and 72%, respectively. The in vitro minimum inhibitory concentration (MIC) values of oxolinic acid against three strains of Vibrio anguillarum isolated from diseased cod were 0.016 μg mL−1 (HI‐610), 0.250 μg mL−1 (HI‐618) and 0.250 μg mL−1 (HI‐A21). Based on a MIC value of 0.016 μg mL−1 a single p.o. administration of 25 mg kg−1 of oxolinic acid maintains plasma levels in excess of 0.064 μg mL−1, corresponding to four times the MIC‐value, for approximately 12 days. The analogous value for a single p.o. dose of 25 mg kg−1 of oxolinic acid administered as vetoquinol was 13 days.
Putative virulence factors of atypical Aeromonas salmonicida isolated from Arctic charr, Salvelinus alpinus (L.), and European grayling, Thymallus thymallus (L.)
Authors: Madetoja J , Pylkkö P , Pohjanvirta T , Schildt L , Pelkonen S
Published: June 2003

Atypical Aeromonas salmonicida (AAS) causes generalized lethal infections in farmed Arctic charr, Salvelinus alpinus (L.), and European grayling, Thymallus thymallus (L.), and is thus a serious threat for culture of these fish species. Virulence factors were studied among isolates of AAS from Arctic charr (n = 20), European grayling (n = 19) and other fish species (n = 20), of which 48 were of Finnish and 11 of Swedish origin. All isolates produced an A‐layer. Extracellular products (ECP) of the AAS isolates did not produce detectable gelatinase and caseinase activity in test assays. Analysis of the same ECP preparations with substrate sodium dodecyl sulphate–polyacrylamide gel electrophoresis showed weak proteolytic activity, indicating the different sensitivity of the detection methods used. The ECP from AAS isolates showed low cytotoxic activity against cultured cells. However, the ECP did not induce mortality in challenged Arctic charr. The results suggest that toxic components, like ECP, secreted by the bacterium may not be the major virulence factor in AAS‐infection in Arctic charr and European grayling, and hence the pathogenesis also differs from the pathogenesis of AAS‐infection in Atlantic salmon, Salmo salar L.
A UK Consensus Group on management of glucocorticoid‐induced osteoporosis: an update
Authors: Eastell R. , Reid D. M. , Compston J. , Cooper C. , Fogelman I. , Francis R. M. , Hosking D. J. , Purdie D. W. , Ralston S. H. , Reeve J. , Russell R. G. G. , Stevenson J. C. , Torgerson D. J.
Published: June 2003

Abstract. Eastell R, Reid DM, Compston J, Cooper C, Fogelman I, Francis RM, Hosking DJ, Purdie DW, Ralston SH, Reeve J, Russell RGG, Stevenson JC, Torgerson DJ (University of Sheffield Medical School, Sheffield; University of Aberdeen, Aberdeen; University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge; Southampton General Hospital, Southampton; Guy's Hospital, London; Freeman Hospital, Newcastle upon Tyne; Nottingham City Hospital, Nottingham; Hull Royal Infirmary, Hull; Wynn Institute for Metabolic Research, London; and the University of York, York, UK). A UK Consensus Group on management of glucocorticoid‐induced osteoporosis: an update (Review). J Intern Med 1998; 244: 271–292.

In the UK, over 250 000 patients take continuous oral glucocorticoids (GCs), yet no more than 14% receive any therapy to prevent bone loss, a major complication of GC treatment. Bone loss is rapid, particularly in the first year, and fracture risk may double. This review, based wherever possible on clinical evidence, aims to provide easy‐to‐use guidance with wide applicability. A treatment algorithm is presented for adults receiving GC doses of 7.5 mg day−1 or more for 6 months or more. General measures, e.g. alternative GCs and routes of administration, and therapeutic interventions, e.g. cyclical etidronate and hormone replacement, are recommended.
Determination of the oral susceptibility of South African livestock‐associated biting midges, Culicoides species, to bovine ephemeral fever virus
Authors: Venter G. J. , Hamblin C. , Paweska J. T.
Published: June 2003

Abstract.  A total of 10 607 Culicoides midges (Diptera: Ceratopogonidae) were fed on either sheep or horse blood containing not less than 6.5 log10 TCID50/ml of bovine ephemeral fever virus (BEFV). Insects were collected during two consecutive summers from two distinct climatic areas. Two seed viruses, originating from either South Africa or Australia, were used separately in the feeding trials. Blood‐engorged females were incubated at 23.5°C for 10 days and then individually assayed in microplate BHK‐21 cell cultures. Of the 4110 Culicoides that survived, 43% were C. (Avaritia) imicola Kieffer and 27% were C. (A.) bolitinos Meiswinkel. The remainder represented 18 other livestock‐associated Culicoides species. Although BEFV was detected in 18.9% of midges assayed immediately after feeding, no virus could be detected after incubation. The absence of evidence of either virus maintenance or measurable replication suggests that most of the abundant livestock‐associated Culicoides species found in South Africa are refractory to oral infection with BEFV. Future studies should be carried out using species of mosquitoes that are associated with cattle in the BEF endemic areas.
Nymphs of the Oriental cockroach (Blatta orientalis) as passive vectors of causal agents of avian tuberculosis and paratuberculosis
Authors: Fischer O. A. , Matlova L. , Dvorska L. , Svastova P. , Pavlik I.
Published: June 2003

Abstract.  The potential transmission of the causal agent of paratuberculosis Mycobacterium avium ssp. paratuberculosis and avian tuberculosis Mycobacterium avium ssp. avium (Actinomycetales: Mycobacteriaceae) by nymphs of the Oriental cockroach Blatta orientalis L. (Blattodea: Blattidae) was investigated by oral infection with mycobacterial suspensions and examination of their droppings and bodies. Both the subspecies of M. avium were isolated from droppings at 3 days post‐infection and M. a. avium was found in homogenized bodies at 10 days post‐infection. The identity of M. a. avium and M. a. paratuberculosis isolates was demonstrated by Restriction Fragment Length Polymorphism (RFLP) analysis. The M. a. avium isolate used as the inoculum and the isolates from the bodies and droppings of the nymphs were shown to be virulent in chickens. The results show that orally infected nymphs of B. orientalis can harbour and shed viable and virulent mycobacteria. This hazard should be considered in the implementation of control measures against mycobacterial infections of animals and humans, which should include destruction of all developmental stages of cockroaches and prevention of their access to materials that can be contaminated by mycobacteria.
Molecular evidence for a kdr‐like pyrethroid resistance mechanism in the malaria vector mosquito Anopheles stephensi
Authors: Enayati A. A. , Vatandoost H. , Ladonni H. , Townson H. , Hemingway J.
Published: June 2003

Abstract.  The mosquito Anopheles stephensi Liston (Diptera: Culicidae) is the urban vector of malaria in several countries of the Middle East and Indian subcontinent. Extensive use of residual insecticide spraying for malaria vector control has selected An. stephensi resistance to DDT, dieldrin, malathion and other organophosphates throughout much of its range and to pyrethroids in the Middle East. Metabolic resistance mechanisms and insensitivity to pyrethroids, so‐called knockdown resistance (kdr), have previously been reported in An. stephensi. Here we provide molecular data supporting the hypothesis that a kdr‐like pyrethroid‐resistance mechanism is present in An. stephensi. We found that larvae of a pyrethroid‐selected strain from Dubai (DUB‐R) were 182‐fold resistant to permethin, compared with a standard susceptible strain of An. stephensi. Activities of some enzymes likely to confer pyrethroid‐resistance (i.e. esterases, monooxygenases and glutathione S‐transferases) were significantly higher in the permethrin‐resistant than in the susceptible strain, but the use of synergists — piperonyl butoxide (PBO) to inhibit monooxygenases and/or tribufos (DEF) to inhibit esterases — did not fully prevent resistance in larvae (permethrin LC50 reduced by only 51–68%), indicating the involvement of another mechanism. From both strains of An. stephensi, we obtained a 237‐bp fragment of genomic DNA encoding segment 6 of domain II of the para type voltage‐gated sodium channel, i.e. the putative kdr locus. By sequencing this 237 bp fragment, we identified one point mutation difference involving a single A–T base change encoding a leucine to phenylalanine amino acid substitution in the pyrethroid‐resistant strain. This mutation appears to be homologous with those detected in An. gambiae and other insects with kdr‐like resistance. A diagnostic polymerase chain reaction assay using nested primers was therefore designed to detect this mechanism in An. stephensi.
Spatial distribution of Culicoides species in Portugal in relation to the transmission of African horse sickness and bluetongue viruses
Authors: Capela R. , Purse B. V. , Pena I. , Wittman E. J. , Margarita Y. , Capela M. , Romão L. , Mellor P. S. , Baylis M.
Published: June 2003

Abstract.  Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midge vectors was carried out at 87 sites within a 50 × 50 km grid distributed across Portugal, using light trap collections at the time of peak midge abundance. Culicoides imicola (Kieffer) made up 66% of the 55 937 Culicoides in these summer collections. It was highly abundant in the central eastern portion of Portugal, between 37°5′ N and 41°5′ N, and in a band across to the Lisbon penninsula (at around 38°5′ N). Of all the complexes, its distribution was most consistent with that of previous outbreaks of Culicoides‐borne disease, suggesting that it may remain the major vector in Portugal. Its distribution was also broadly consistent with that predicted by a recent climate‐driven model validating the use of remote sensing datasets for modelling of Culicoides distribution. Adult C. imicola were found to have overwintered at 12 of 20 sites re‐surveyed in winter but it did so in very low numbers. Culicoides obsoletus (Meigen) and Culicoides pulicaris (Linnaeus) complex midges were widespread despite their low summer abundance. The observed coincidence of high abundances of C. imicola and high abundances of C. pulicaris in summer lead us to suggest that C. imicola could bring African horse sickness virus or bluetongue virus into contact with C. pulicaris and the latter complex, together with C. obsoletus, could then transmit these viruses across much wider areas of Europe. The fact that adult C. pulicaris are present in high abundances in winter may provide a mechanism by which these viruses can overwinter in these areas.
Low temperature episodes in development of blowflies: implications for postmortem interval estimation
Authors: Ames C. , Turner B.
Published: June 2003

Abstract.  Traditionally the calculation of accumulated degree days or hours (ADD or ADH) involves the concept of a minimum threshold temperature below which development ceases. Hence in fluctuating conditions, where temperatures drop below this threshold, there may be periods of time when development is taken to be zero. This has important implications when the calculation of postmortem interval (PMI) is based on the ADD or ADH of larval dipterans. Normal development of larvae of the blowflies Calliphora vicina Robineau‐Desvoidy and C. vomitoria L. (Diptera: Calliphoridae) at 20°C was interrupted by cold episodes. The expectation was that total development time would increase by the period at low (therefore no development) temperature but the total ADD or ADH should be the same as non‐cold treated cohorts. The results, however, showed that total ADH for both species decreased linearly with increasing temperature with no evidence of any minimum threshold temperature effect. The increased ADH at low temperatures may be due to either continued but reduced development or a delay in development restarting after the cold episode. Use of ADH in PMI estimations has shortcomings particularly during the winter period where low temperatures are involved or where there are sudden summer cold spells during the development period. As blowfly development progresses from egg to pupa such errors will be compounded.
Sublethal iridovirus disease of the mosquito Aedes aegypti is due to viral replication not cytotoxicity
Authors: Marina C. F. , Ibarra J. E. , Arredondo‐Jiménez J. I. , Fernández‐Salas I. , Valle J. , Williams T.
Published: June 2003

Abstract.  Invertebrate iridescent viruses (Iridoviridae) possess a highly cytotoxic protein. In mosquitoes (Diptera: Culicidae), invertebrate iridescent virus 6 (IIV‐6) usually causes covert (inapparent) infection that reduces fitness. To determine whether sublethal effects of IIV‐6 are principally due to cytotoxicity of the viral inoculum (which inhibits macromolecular synthesis in the host), or caused by replication of the virus larvae of the mosquito Aedes aegypti (L) were exposed to untreated IIV‐6 virus that had previously been deactivated by heat or ultraviolet light. Control larvae were not exposed to virus. Larval development time was shortest in control larvae and extended in larvae exposed to untreated virus. Covertly infected mosquitoes laid significantly fewer eggs, produced between 20 and 35% fewer progeny and had reduced longevity compared to other treatments. Wing length was shortest in mosquitoes exposed to heat‐deactivated virus. Multivariate analysis of the same data identified fecundity and progeny production as the most influential variables in defining differences among treatments. Overall, viral infection resulted in a 34% decrease in the net reproductive rate (R0) of covertly infected mosquitoes, vs. only 5–17% decrease of R0 following treatments with deactivated virus, compared to controls. Sublethal effects of IIV‐6 in Ae. aegypti appear to be mainly due to virus replication, rather than cytotoxic effects of the viral inoculum.
Natural skip oviposition of the mosquito Aedes aegypti indicated by codominant genetic markers
Authors: Colton Y. M. , Chadee D. D. , Severson D. W.
Published: June 2003

Abstract.  This study examines the use of codominant restriction fragment length polymorphism (RFLP) markers to estimate the number of sibling families found within and among oviposition sites used by the mosquito Aedes aegypti (L) (Diptera: Culicidae). Estimates were made using pairwise relatedness (rxy) calculations based on alleles shared between individuals. Genotypes for eight laboratory mosquito families were determined at six RFLP loci and the observed allele frequencies were used to generate simulated distributions of rxy from full‐sibling and unrelated pairs of individuals. The midpoint (mp) between the means of the pairwise rxy distributions was used to discriminate full‐sibling families from unrelated families. Clusters of individuals with rxy values higher than the mp value were grouped as putative sibling families. This method was tested by calculating actual rxy for all pairwise comparisons of the known laboratory full‐sibling and paternal half‐sibling families, followed by upgma cluster analysis to group sibling families. The technique was then used for sibling estimations on wild caught mosquitoes collected at three locations in Trinidad, West Indies. From field populations, 35 families were estimated among 122 individuals tested with an average of 6.2 families per container. Members of 19 predicted families clustered as groups across multiple containers, providing molecular evidence for skip‐oviposition behaviour in Ae. aegypti females, whereby individual females oviposit in more than one container.
A method for extraction and analysis of high quality genomic DNA from ixodid ticks
Authors: Hill C. A. , Gutierrez J. A.
Published: June 2003

Abstract.  Currently, no published methods describe the extraction of high molecular weight genomic DNA from ixodid ticks (Acari: Ixodidae) and commonly used methods of extraction are not well adapted for use with members of this family. A method for extraction of minimally degraded genomic DNA from ixodid ticks that can be completed in one or two days is described. The method produces DNA which is of sufficient size (>24 kb) for use in Southern analysis and which is readily digestible by restriction endonucleases. Southern analysis using a cytochrome P450 gene probe, demonstrates the success of our method with genomic DNA extracted from two species of Ixodidae, the lone star tick, Amblyomma americanum (Linnaeus) and the cattle fever tick, Boophilus microplus (Canestrini).
In vitro efficacy of extracts of Melia azedarach against the tick Boophilus microplus
Authors: Borges L. M. F. , Ferri P. H. , Silva W. J. , Silva W. C. , Silva J. G.
Published: June 2003

Abstract.  The efficacy of ripe fruit extracts of Melia azedarach L. (Rutales: Meliaceae) was evaluated against the tick, Boophilus microplus (Canestrini) (Acari: Ixodidae). Ripe fruits of M. azedarach dried and powdered were extracted by Soxhlet apparatus successively using hexane, CHCl3 and 96% aqueous ethanol. Larvae and engorged females were immersed in decreasing concentrations from 0.25% to 0.015% of each extract. The mortality of larvae was evaluated 24, 72 and 168 h after treatment. The effectiveness of treatment against engorged females was assessed by measuring egg production. All tested extracts caused mortality of B. microplus larvae, with higher mortality rates observed in CHCl3 (100%) and hexanic extract (98%) than in ethanolic extract (50%) 168 h after treatment. The mortality was dependent on concentration and on time after treatment. Similarly hexanic and CHCl3 extracts showed higher effectiveness (varying from 14% to 100%) against B. microplus engorged females than ethanolic extract (varying from 0% to 46%). Melia azedarach extracts did not kill the adult females, but inhibited partially or totally egg production and embryogenesis. These results show that the less polar the extract of M. azedarach ripe fruits the more its effectiveness against larvae and engorged females of B. microplus. This plant may therefore be useful in the control of resistant B. microplus populations.
Field evaluation of a lethal ovitrap against dengue vectors in Brazil
Authors: Perich M. J. , Kardec A. , Braga I. A. , Portal I. F. , Burge R. , Zeichner B. C. , Brogdon W. A. , Wirtz R. A.
Published: June 2003

Abstract. Field evaluation of a ‘lethal ovitrap’ (LO) to control dengue vector Aedes mosquitoes (Diptera: Culicidae), was undertaken in two Brazilian municipalities, Areia Branca and Nilopolis, in the State of Rio de Janeiro. The LO is designed to kill Aedes via an insecticide‐treated ovistrip (impregnated with deltamethrin). In each municipality, the intervention was applied to a group of 30 houses (10 LOs/house) and compared to 30 houses without LOs in the same neighbourhood. Five LOs were put outside and five LOs inside each treated house.

Three methods of monitoring Aedes density were employed: (i) percentage of containers positive for larvae and/or pupae; (ii) total pupae/house; (iii) total adult females/house collected by aspirator indoors. Weekly mosquito surveys began during the month before LO placement, by sampling from different groups of 10 houses/week for 3 weeks pre‐intervention (i.e. 30 houses/month) and for 3 months post‐intervention in both treated and untreated areas.

Prior to LO placement at the end of February 2001, Aedes aegypti (L) densities were similar among houses scheduled for LO treatment and comparison (untreated control) at each municipality. Very few Ae. albopictus (Skuse) were found and this species was excluded from the assessment. Post‐intervention densities of Ae. aegypti were significantly reduced for most comparators (P < 0.01), as shown by fewer positive containers (4–5 vs. 10–18) and pupae/house (0.3–0.7 vs. 8–10) at LO‐treated vs. untreated houses, 3 months post‐treatment at both municipalities. Numbers of adult Ae. aegypti females indoors were consistently reduced in LO‐treated houses at Areia Branca (3.6 vs. 6.8/house 3 months post‐intervention) but not at Niloplis (∼3/house, attributed to immigration). These results demonstrate sustained impact of LOs on dengue vector population densities in housing conditions of Brazilian municipalities.
The poultry red mite, Dermanyssus gallinae, a potential vector of Erysipelothrix rhusiopathiae causing erysipelas in hens
Authors: Chirico J. , Eriksson H. , Fossum O. , Jansson D.
Published: June 2003

Abstract.  Erysipelas is a bacterial disease caused by Erysipelothrix rhusiopathiae, which may infect swine as well as several other species of mammals and birds, including domestic fowl. In poultry, erysipelas may cause sudden high mortality due to septicemia. This communication describes the first isolation of E. rhusiopathiae from the haematophagous poultry red mite, Dermanyssus gallinae DeGeer (Acari: Dermanyssidae), that was collected on three farms where hen erysipelas was diagnosed. The bacteria were isolated from the integument as well as from the interior of the mites. Serotypes 1a and 1b of E. rhusiopathiae found in the mites corresponded with those isolated from the diseased birds. These findings imply that D. gallinae is a potential vector of E. rhusiopathiae. The current lack of effective measures to control D. gallinae causes reoccurring mite problems in poultry facilities once afflicted by this parasite. Consequently, mites containing E. rhusiopathiae may act as reservoir hosts of this bacterium, allowing it to persist in the poultry house between flock cycles as a source of infection for the replacement pullets. The zoonotic potentials of both E. rhusiopathiae and D. gallinae should also be considered.
Dipteran predators of Simuliid blackflies: a worldwide review
Authors: Werner D. , Pont A. C.
Published: June 2003

Abstract. Haematophagous female blackflies (Diptera: Simuliidae) are serious biting pests and obligate vectors of vertebrate pathogens, namely filarialDirofilaria,Mansonella,Onchocercaand protozoalLeucocytozoon. Immature stages of Simuliidae inhabit lotic waterways, the sessile larvae filter‐feeding and often forming a large proportion of the benthic biomass, usually aggregated in well‐oxygenated sections of streams, rivers, waterfalls and spillways. Simuliid control practices depend on larvicidal chemicals, biological products (bacteria, nematodes) and environmental modification. The potential use of predators for biological control of Simuliidae has not been exploited. Predators of Simuliidae include examples of at least 12 families of Diptera and other predaceous arthropods (Crustacea and insects: Coleoptera, Odonata, Plecoptera, Trichoptera), invertebrates (notably Turbellaria), as well as browsing fish. Diptera impacting upon simuliid populations comprise mainly Chironomidae, Empididae and Muscidae, although several other families (Asilidae, Dolichopodidae, Phoridae, Drosophilidae, Scathophagidae) play a significant role as predators. Details of predator and prey species and life stages are presented, by zoogeographical region, including the prevalence of cannibalism among Simuliidae.