How parasitism affects critical patch-size in a host–parasitoid model: application to the forest tent caterpillar

Habitat structure has broad impacts on many biological systems. In particular, habitat fragmentation can increase the probability of species extinction and on the other hand it can lead to population outbreaks in response to a decline in natural enemies. An extreme consequence of fragmentation is the isolation of small regions of suitable habitat surrounded by a large region of hostile matrix. This scenario can be interpreted as a critical patch-size problem, well studied in a continuous time framework, but relatively new to discrete time models. In this paper we present an integrodifference host-parasitoid model, discrete in time and continuous in space, to study how the critical habitat-size necessary for parasitoid survival changes in response to parasitoid life history traits, such as emergence time. We show that early emerging parasitoids may be able to persist in smaller habitats than late emerging species. The model predicts that these early emerging parasitoids lead to more severe host outbreaks. We hypothesise that promoting efficient late emerging parasitoids may be key in reducing outbreak severity, an approach requiring large continuous regions of suitable habitat. We parameterise the model for the host species of the forest tent caterpillar Malacosoma disstria Hbn., a pest insect for which fragmented landscape increases the severity of outbreaks. This host is known to have several parasitoids, due to paucity of data and as a first step in the modelling we consider a single generic parasitoid. The model findings are related to observations of the forest tent caterpillar offering insight into this host-parasitoid response to habitat structure.

Climate and competition: the effect of moving range boundaries on habitat invasibility

Predictions for climate change include movement of temperature isoclines up to 1000 m/year, and this is supported by recent empirical studies. This paper considers effects of a rapidly changing environment on competitive outcomes between species. The model is formulated as a system of nonlinear partial differential equations in a moving domain. Terms in the equations describe competition interactions and random movement by individuals. Here the critical patch size and travelling wave speed for each species, calculated in the absence of competition and in a stationary habitat, play a role in determining the outcome of the process with competition and in a moving habitat. We demonstrate how habitat movement, coupled with edge effects, can open up a new niche for invaders that would be otherwise excluded.

Could preferential prescribing and referral behaviour of physicians explain the elevated thrombosis risk found to be associated with third generation oral contraceptives?

BACKGROUND

Recently published case-control studies on third versus second generation oral contraceptives showed a slightly increased risk for venous thromboembolism (VTE) and led to a discussion about biases or confounders external to the study such as, preferential prescribing of third generation pills to women at higher risk and differential diagnostic behaviour.

METHODS

An interview survey with 102 physicians was performed in 2 weeks of December 1995 in Germany and 1209 of their patients were included in a retrospective cohort analysis of drug utilization and risk markers.

RESULTS

German physicians previously preferred to prescribe third generation pills whenever an increased risk was perceived, i.e. risk for VTE and for arterial thrombosis (risk factors, personal or family history of cardiovascular diseases). Almost all predefined risk scenarios were associated with an increased attention to non-specific venous symptoms and patients were more frequently sent for intensive diagnostic search for venous thromboses. The behaviour was not directly dependent on the type of OC; however the third generation pills were indirectly associated with higher risk in the pill-taking women. The physicians' view was confirmed by the analysis of the cohorts of patients: preferential prescribing was also found in this data set, although it was not as impressive as in the physicians responses.

CONCLUSION

The possibility cannot be excluded that preferential prescribing and differential diagnostic behaviour alone could have explained the roughly two-fold increased odds ratios from case-control studies recently published, had this information been available among the study variables.

Complete necrosis of allograft ureter after cadaveric renal transplantation

Complete necrosis of a transplant ureter is a rare complication that needs to be considered early in cases of severe graft dysfunction if successful surgical intervention and restoration of graft function is to be achieved. We report on two cases of this complication occurring in children and discuss the surgical management. Surgical exploration of grafts where there is an early sudden decline in function is imperative as routine imaging will not exclude this potentially treatable problem.

A fully coupled binary biochemical reactive-diffusion model with analytic solution

Coupled multicomponent biochemical reactive diffusion underlies a variety of biological signalling processes and pharmacokinetic applications, such as paracrine signalling involving "cocktails" comprised of growth promoter/inhibitor factors and proteases associated with tumor angiogenesis, invasion and metastasis, extravascular drug delivery, and polymeric controlled-release drug codelivery design. Here, we present a model and develop a new analytic solution to illustrate the spatiotemporal behavior associated with fully coupled binary biochemical reactive diffusion. The complete coupling renders the solution appreciably more complex in structure and behavior than solutions for unicomponent or partially coupled models. Concentration behavior is illustrated by the computational simulation of binary-species tumor angiogenesis factor reactive-diffusion in the extravascular tissue matrix. The computational results indicate that (a) steady-state concentration profiles are achieved within 1 h of a change in factor production; (b) in the steady state, the spatial profiles of the two components tend to be similar; (c) exceedingly steep concentration gradients, involving several orders-of-magnitude differences in concentration over a few tenths of a millimeter, can occur in the vicinity of boundary sources due to inter-species reaction; (d) the concentration profiles of the two species differ from unicomponent predictions due to the simultaneous mass interchange between the two species. The analytic solution predictions are also used to provide a first-ever validation of a time-dependent, binary-component Crank-Nicholson numerical solution. The ability to quantitatively model interacting and often strongly varying concentration levels as a function of time and position can serve as a powerful complementary tool to experimental analyses for assessing disease state and interventional pharmacological efficacy, especially when the spatial scales on which in vivo behavior occurs taxes the limits of imaging capabilities.

Serum leptin and IGF-I during growth hormone treatment in chronic renal failure

Serum leptin decreases during growth hormone (hGH) treatment and pre-treatment values have been suggested as a predictor of the response to hGH in GH deficiency (GHD) but not in non-GHD syndromes. To investigate whether this holds true in children with chronic renal failure (CRF), we evaluated changes in serum leptin, insulin-like growth factor-I (IGF-I) and height before(b) and during the 1st year (3 months, 6 months, 9 months, 12 months) of hGH treatment (1 IU/kg per week) in 11 children (median age(b) 10.1 years, mean height(b) -2.9 SDS) with CRF. Serum leptin and IGF-I were compared with values from healthy children. Each patient also served as his/her own control, with values during treatment compared with those before treatment. Growth improved in all patients during treatment (mean change(12 m) +7.2 cm, change in height SDS(12 m) +0.5, P=0.001). Weight decreased (median decrease(12 m) 0.3 SDS, P=0.02) but body mass index (BMI) and serum leptin did not change during treatment. Serum IGF-I levels were low before (mean -1.1 SDS) but increased during hGH treatment, the increment being greatest at 10 days (mean increment +1.9 SDS, P<0.0001). Serum leptin(b) did not correlate with change in serum IGF-I(10d), height(12 m) or weight(12 m). Serum IGF-I SDS(b) correlated with height SDS at 12 months ( r=0.80, P=0.006) of hGH treatment. Serum leptin(b) correlated with BMI ( r(s)=0.75, P=0.01). Levels adjusted for BMI did not differ from values in healthy children and did not change during treatment. Despite an IGF-I and growth response during hGH treatment, serum leptin did not change and pre-treatment values did not predict the growth response in these children with CRF.

An evaluation of the use of colonized periphyton as an indicator of wastewater impact in near-coastal areas of the Gulf of Mexico

Receiving water impacts of point source discharges to the Gulf of Mexico are seldom reported on indigenous flora. The objective of this research was to evaluate the ability of colonized periphyton to provide this information. Water quality and biomass and pigment concentrations of the periphyton were determined at 27 stations located above and below 8 wastewater discharges. Most physicochemical parameters and concentrations of pesticides and PCBs were either unchanged or below detection in the receiving waters, which contrasted occasional increases in concentrations of several trace metals and nutrients. The response of the periphyton was specific to the wastewater, colonization station, response parameter, and colonization period. Statistically significant differences in biomass and pigment content occurred for at least one colonization station located below each of the eight outfalls. This represented a total of 18 of the 21 stations located in wastewater-impacted areas. Phytostimulation was more common than inhibition. Ash-free dry weight increased, on average, by 181% (+/- 1 SD = 123%) and chlorophyll a increased by 356% (+/- 593%) in wastewater-impacted areas. The in situ phytostimulation paralleled the stimulatory trend observed in standardized NPDES whole effluent tests conducted with cultured microalgae for four of eight wastewaters. The use of colonized periphyton as an indicator of wastewater impact was not simple. Spatial variation in response needs consideration to ensure relevancy of the results if this assessment methodology is used for near-coastal wastewater hazard evaluations.

Oral health status of adults from a California regional center for developmental disabilities

The oral health status and treatment needs of developmentally disabled adults (18 years and older) from a Los Angeles Regional Center who live in a variety of settings were measured as part of a comprehensive study to determine their overall health status. A dental assessment was performed on a sample of 325 persons which was similar in demographic composition to the entire population at the center. Approximately 80% of clients reported a personal dentist of record, and 73% brushed their own teeth. Edentulism was 9%. The mean number of retained teeth per person was 22. Subjectively, 15.7% of the sample was rated as having "good" overall dental health, 77.7% "fair," and 6.6% "poor." The major reasons rendering fair or poor assessments were oral hygiene, clinical periodontal disease, and dental caries. More females than males were assessed as having "good" overall dental health. The overall appearance of the teeth for a majority of the sample (76.5%) was rated as "same as most." Persons who brushed their own teeth had fewer missing teeth than those who did not. Persons with a dentist of record had fewer decayed and more filled teeth. Persons living at home with family or friends had a significantly lower DMFT index than those living independently or in facilities. In general, these findings are encouraging; however, caution must be exercised, since efforts to improve the oral health status of this population require continued attention.

Strain persistence of invasive Candida albicans in chronic hyperplastic candidosis that underwent malignant change

OBJECTIVES

The aim of this study was to assess persistence and tissue invasion of Candida albicans strains isolated from a 65 year-old patient with chronic hyperplastic candidosis (CHC), that subsequently developed into squamous cell carcinoma (SCC).

MATERIALS AND METHODS

C. albicans (n=7) were recovered from the oral cavity of the patient over seven years. Confirmation of CHC and SCC in this patient was achieved by histopathological examination of incisional biopsy tissue. DNA fingerprinting was performed on the seven isolates from the CHC patient together with a further eight isolates from patients with normal oral mucosa (n=2), chronic atrophic candidosis (n=1), SCC (n=1) and CHC (n=4). Genotyping involved the use of inter-repeat PCR using the eukaryotic repeat primer 1251. Characterisation of the tissue invasive abilities of the isolates was achieved by infecting a commercially available reconstituted human oral epithelium (RHE; SkinEthic, Nice, France). After 24 h, C. albicans tissue invasion was assessed by histopathological examination.

RESULTS

DNA fingerprinting demonstrated strain persistence of C. albicans in the CHC patient over a seven year period despite provision of systemic antifungal therapy. The strain of C. albicans isolated from this patient was categorised as a high invader within the RHE compared to other isolates.

CONCLUSIONS

Candidal strain persistence was evident in a patient with CHC over seven years. This persistence may be due to incomplete eradication from the oral cavity following antifungal therapy or subsequent recolonisation from other body sites or separate exogenous sources. The demonstration of enhanced in vitro tissue invasion by this particular strain may, in part, explain the progression to carcinoma.

Drug use and adverse event monitoring in German children

OBJECTIVE

To assess drug use and the incidence of mild to moderate adverse drug effects (AE) in children aged 0 - 16 years, with 2 different approaches.

METHODS

All 185 pediatric practices in the State of Brandenburg, Germany, were surveyed (95% positive response). A random sample of 50 practices servicing 36,000 children participated in the study as sentinel physicians reporting any AE among their patients. Twenty practices servicing 14,000 children were included in a drug utilization component (DUC) which documented diagnoses, prescribing and AE in all children seen in a 3-month period.

RESULTS

The results on the DUC are based on 12,628 children with 26,168 physician contacts, 34,465 diagnoses and 33,140 drug prescriptions given to 85% of the children seen (average age: 6.7 years). Practice size ranged from 94 to 1,473 children seen in a 3-month period. The average number of physician contacts per child was 2. 1, with 10% seeing a physician 5 times and more. The diagnoses were respiratory ailments (30%), skin- (12%), injection- (11%) and trauma- (10%) related diagnoses. Major drug uses were respiratory (34% of prescriptions), anti-infective (22%), dermatological (13%), gastrointestinal (9%) and psychotropic agents (8%). One hundred and fifty-two AE affecting 150 children were documented in the DUC, 60% of these occurring within 3 days after treatment initiation. 83% of AE were mild (up to 4 on a scale from I -6), and 85% were considered by physicians to be attributable. Only 4 reports of very severe events were received. 47% of reports were related to antibiotic uses, 31% to immunizations, 11% to respiratory, and 4% to gastrointestinal agents. While there are no differences in the occurrence of AE by gender, AE decreases significantly by age, maintaining the same patterns of AE type and causative medication. Over a 3-month period, the incidence of mild to moderate ADR in children given medications is estimated as 1,200 per 100,000, or about 1%.

CONCLUSIONS

Underreporting of AE remains an issue even when a monitoring scheme suggests compliance. The results of this study show that while AE in children are generally non-serious, 1% of treatments might elicit mild AE leading to a consultation. Direct practice recording produces more reports than a sentinel system.

PCR fingerprinting of Candida albicans associated with chronic hyperplastic candidosis and other oral conditions

The purpose of this study was to genotype strains of Candida albicans to determine whether specific types were associated with chronic hyperplastic candidosis (CHC). A total of 67 candidal isolates from CHC patients (n = 17) and from patients with other oral conditions (n = 21) were genotyped by PCR fingerprinting employing two interrepeat primer combinations (1245 and 1246 primers or 1251 primer) and a single minisatellite-specific M13 primer. The most suitable primer for fingerprint analysis was found to be primer 1251, yielding well-resolved banding patterns. For the 67 isolates tested, PCR fingerprinting delineated 25 (1245 and 1246 primers), 27 (1251 primer), and 25 (M13 primer) profiles. The majority of C. albicans isolates from multiple sites within the mouth produced identical profiles (six out of nine subjects examined). For patients for whom a series of longitudinal isolates was available, strain persistence for up to 7 years was evident for five out of eight individuals, despite episodes of antifungal therapy. Computer-assisted comparison of the interrepeat PCR fingerprints identified seven distinct profiles that were shared among isolates from different individuals. However, no association was evident among isolates of C. albicans from specific clinical conditions. Eight isolates that were initially identified as C. albicans but having atypical PCR profiles were later confirmed as Candida dubliniensis. In conclusion, the genotypic data do not indicate clonal restriction of C. albicans with respect to CHC. Furthermore, these results have demonstrated that in the majority of individuals, colonizing populations of C. albicans are clonal in nature and exhibit strain persistence.

Measurement of heat conduction through stacked screens

This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with the apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter and 55 mm in length. The cold end of the stacked screens is cooled by a Gifford-McMahon (GM) cryocooler at cryogenic temperature, and the hot end is maintained at room temperature. Heat conduction through the screens is determined from the temperature gradient in a calibrated heat flow sensor mounted between the cold end of the stacked screens and the GM cryocooler. The samples used for these experiments consisted of 400-mesh stainless steel screens, 400-mesh phosphor bronze screens, and two different porosities of 325-mesh stainless steel screens. The wire diameter of the 400-mesh stainless steel and phosphor bronze screens was 25.4 micrometers and the 325-mesh stainless steel screen wire diameters were 22.9 micrometers and 27.9 micrometers. Standard porosity values were used for the experimental data with additional porosity values used on selected experiments. The experimental results showed that the helium gas between each screen enhanced the heat conduction through the stacked screens by several orders of magnitude compared to that in vacuum. The conduction degradation factor is the ratio of actual heat conduction to the heat conduction where the regenerator material is assumed to be a solid rod of the same cross sectional area as the metal fraction of the screen. This factor was about 0.1 for the stainless steel and 0.022 for the phosphor bronze, and almost constant for the temperature range of 40 to 80 K at the cold end.

Oral submucous fibrosis in a 11-year-old Bangladeshi girl living in the United Kingdom

A case of oral submucous fibrosis occurring in a 11-year-old Bangladeshi girl is presented. This paper reviews the aetiology, clinical presentation and treatment modalities of oral submucous fibrosis. This case highlights the link between oral submucous fibrosis and the regular use of areca-nut (paan) and the newer transcultural oral tobacco products. This association has been reported among children resident in the Indian sub-continent but is unrecorded for United Kingdom residents. The case report underlines the danger that children face with products which are clearly targeted at them by the tobacco industry.

Bullying in nursing

BACKGROUND

Current concerns about the need to improve the working lives of health service staff are well founded, and are receiving new impetus in current NHS human resource practice. However, the incidence of bullying in nursing would seem particularly problematic considering its effect on such a large proportion of the health service workforce. This article deals with a number of pertinent issues regarding what might constitute bullying and the growth of the phenomenon. In particular, the lessons we can learn in relation to its impact on patient care should be of concern.

CONCLUSION

Ongoing research by the author is beginning to indicate that managerial and often union recognition and handling of such problems is frequently far from satisfactory. The article concludes with some suggestions for improvements.

Sediment chemical contamination and toxicity associated with a coastal golf course complex

The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities of sediments impacted by a coastal golf course complex. Sediment contaminant concentrations were determined at least twice during the two-year study period at 14 sampling stations. In addition, a combination of acute and chronic bioassays were conducted exposing four invertebrate test species to whole sediments and associated pore waters. Overall, the Florida, USA, golf course complex had a measurable impact on sediment chemical quality, particularly in near-field areas. Higher concentrations of several trace metals and organochlorine pesticides were detected in many golf course-associated sediments compared with reference areas; however, concentrations decreased seaward and only a few, primarily chlorinated pesticides, exceeded proposed sediment quality guidelines. Chromium, zinc, and mercury were detected more frequently than other trace metals. The DDT and associated metabolites, dieldrin and chlordane, were the more commonly detected organic contaminants. Acute toxicity was uncommon and occurred consistently for sediment collected from one coastal location. In contrast, chronic toxicity occurred at several study sites based on the response of Mysidopsis bahia. It was concluded that the impact of golf course runoff on sediment quality may be subtle and sensitive biological assessment methods, such as chronic toxicity tests, will be needed to detect adverse effects.

How predation can slow, stop or reverse a prey invasion

Observations on Mount St Helens indicate that the spread of recolonizing lupin plants has been slowed due to the presence of insect herbivores and it is possible that the spread of lupins could be reversed in the future by intense insect herbivory [Fagan, W. F. and J. Bishop (2000). Trophic interactions during primary sucession: herbivores slow a plant reinvasion at Mount St. Helens. Amer. Nat. 155, 238-251]. In this paper we investigate mechanisms by which herbivory can contain the spatial spread of recolonizing plants. Our approach is to analyse a series of predator-prey reaction-diffusion models and spatially coupled ordinary differential equation models to derive conditions under which predation pressure can slow, stall or reverse a spatial invasion of prey. We focus on models where prey disperse more slowly than predators. We comment on the types of functional response which give such solutions, and the circumstances under which the models are appropriate.

ESS analysis of mechanistic models for territoriality: the value of scent marks in spatial resource partitioning

In this paper elements of game theory are used to analyse a spatially explicit home range model for interacting wolf packs. The model consists of a system of nonlinear partial differential equations whose parameters reflect the movement behavior of individuals within each pack and whose solutions describe the patterns of space-use by each pack. By modifying the behavioral parameters, packs adjust their patterns of movement so as to maximize their reproductive output. This involves a tradeoff between maximizing prey intake and minimizing conflict with neighbors. Evolutionarily stable choices of the behavioral parameters yields territories that are immune to invasion by groups with alternate behaviors.

Correlates of actual and perceived knowledge of prostate cancer among African Americans

While digital rectal examination, prostate-specific antigen, and transrectal ultrasound have been identified as effective means of early detection of prostate cancer, African American men tend to underuse these services as compared to white men. Using a nonrandom sample of 108 African American men, the authors conducted an exploratory investigation of the effects of education, income, age, and health insurance coverage on actual and perceived knowledge of prostate cancer. The extent to which the use of prostate cancer screening services may be attributed to actual and perceived knowledge of prostate cancer was also explored. Respondents demonstrated a poor knowledge of prostate cancer and less than 40% reported having had prostate cancer screening as part of their annual physical examination. The results of the study also revealed that (a) there was a moderately strong correlation between actual and perceived knowledge of prostate cancer, (b) use of prostate cancer screening service was positively associated with actual and perceived knowledge of the disease, (c) actual knowledge of prostate cancer was negatively correlated with education, age, and income, and (d) actual and perceived knowledge of prostate cancer were both correlated with having health insurance coverage.

Identification of Candida dubliniensis, based on ribosomal DNA sequence analysis

Differentiation of Candida albicans and the recently described C. dubliniensis has proven difficult due to the high degree of phenotypic similarity of these species. The present study examines sequence variations in the ribosomal DNA (rDNA) intergenic transcribed spacer (ITS) regions of C. albicans (n = 5) and C. dubliniensis (n = 7) strains, with a view to identifying sequence differences that would enable consistent differentiation of these two species by restriction fragment length polymorphism (RFLP) analysis. The ITS1 and ITS2 regions, together with the entire 5.8S rRNA gene of the strains, were amplified by the polymerase chain reaction (PCR), using primers ITS1 and ITS4, PCR products from both C. albicans and C. dubliniensis were of similar size (around 540 bp); however, sequence analysis revealed over 20 consistent base differences between the products of the two species. On the basis of sequence variation, the restriction enzyme MspA1 I was selected and used to differentiate the PCR products of C. albicans and C. dubliniensis by RFLP analysis. MspA1 I yielded two discernible fragments from C. albicans PCR products, whilst those from C. dubliniensis appeared undigested, thereby providing an approach to differentiate the two species.

A molecular epidemiological study of sequential oral isolates of Candida albicans from terminally ill patients

The pattern of candidal colonisation was studied in a group of terminally ill patients receiving antifungal treatment for oral candidosis. A total of 43 isolates of C. albicans was collected pre- and post-antifungal treatment from patients up to a maximum period of 4 weeks. Isolates were analysed by electrophoretic karyotyping (EK) and by inter-repeat polymerase chain reaction (IR-PCR). Fifteen electrophoretic karyotypes and 17 IR-PCR profiles were identified. Sequential isolates from 10 patients yielded identical profiles in both EKs and IR-PCR analyses. In the case of four patients, minor differences in the profiles were obtained by either EK or IR-PCR. The findings suggest that antifungal treatment in this patient group fails to eradicate the original C. albicans strain, thereby allowing recolonisation of the oral cavity. The present study has also shown that either EK or IR-PCR is a useful typing approach in such epidemiological investigations.

Alpha(2) adrenoceptor agonists as potential analgesic agents. 3. Imidazolylmethylthiophenes

A series of imidazolylmethylthiophenes has been prepared and evaluated as ligands for the alpha(2) adrenoceptor. These compounds were tested in two animal models that are predictive of analgesic activity in humans. The 3-thienyl compounds were generally the most potent, particularly those with substitution in the 4-position. A subset of the most active compounds was further evaluated for adverse cardiovascular effects in the anesthetized rat model. In addition to excellent binding at the alpha(2D) adrenoceptor, the 4-bromo analogues 20e and 21e were very active in the rat abdominal irritant test (RAIT) with ED(50) doses of 0.38 and 0.31 mg/kg, respectively. We constructed a pharmacophore model based on the biological activity of the present series, dexmedetomidine (1), and conformationally restrained analogues 3 and 4.

Electron capture dissociation of gaseous multiply charged ions by Fourier-transform ion cyclotron resonance

Fourier-transform ion cyclotron resonance instrumentation is uniquely applicable to an unusual new ion chemistry, electron capture dissociation (ECD). This causes nonergodic dissociation of far larger molecules (42 kDa) than previously observed (<1 kDa), with the resulting unimolecular ion chemistry also unique because it involves radical site reactions for similarly larger ions. ECD is highly complementary to the well known energetic methods for multiply charged ion dissociation, providing much more extensive protein sequence information, including the direct identification of N- versus C-terminal fragment ions. Because ECD only excites the molecule near the cleavage site, accompanying rearrangements are minimized. Counterintuitively, cleavage of backbone covalent bonds of protein ions is favored over that of noncovalent bonds; larger (>10 kDa) ions give far more extensive ECD if they are first thermally activated. This high specificity for covalent bond cleavage also makes ECD promising for studying the secondary and tertiary structure of gaseous protein ions caused by noncovalent bonding.