bluuebunny/crossref_metadata_2025 huggingface dataset:
Human hepatocytes transplanted into genetically immunocompetent rats are susceptible to infection by hepatitis B virus in situ
Authors: Wu C. H. , Ouyang E. C. , Walton C. M. , Wu G. Y.
Published: March 2003

Immune tolerance of human cells without generalized immunosuppression was created in groups of normal fetal rats at 17 days of gestation by inoculation ip with primary human hepatocytes in utero. One day after birth, suspensions of human hepatocytes were transplanted via intrasplenic injection and one week later groups of rats were inoculated with hepatitis B virus (HBV). Tolerized rats that were transplanted with human hepatocytes and subsequently infected with HBV produced hepatitis B surface antigen (HBsAg) in serum beginning on day 3. Levels rose fivefold and remained stable at 0.75 pg/ml through at least 60 days. Of cells that stained positive for human serum albumin, approximately 30% were found to be also positive for HBsAg by immunohistochemistry. Serum HBV DNA was detectable from 1 to 15 weeks postinfection. Finally, covalently closed circular DNA, reflecting HBV replication, was found in liver and serum. Controls that were tolerized and not transplanted, but inoculated with HBV, as well as untreated controls, had no evidence of HBV gene expression or replication under identical conditions. The data support the conclusion that primary human hepatocytes transplanted into genetically immunocompetent rodent hosts, survive and maintain sufficient differentiation to produce human serum albumin and be infected by HBV.
Possible role of human interleukin‐6 and soluble interleukin‐6 receptor in hepatitis B virus infection
Authors: Heinz D. , Peters M. , Prange R. , Gerken G. , Rose‐John S.
Published: March 2003

Human interleukin‐6 has been shown to promote hepatitis B virus (HBV) infection. However, it is not clear whether this influence is the result of a direct interaction between interleukin‐6 (IL‐6) and the HBV envelope proteins or of a rather indirect mechanism. A direct interaction of IL‐6 and the preS region of the large envelope protein (L‐protein) of HBV has been reported. In this study we assessed the binding of IL‐6 and of the IL‐6 receptor subunits to the preS region of the L‐protein of HBV. Binding of IL‐6 and IL‐6 receptor subunits sIL‐6R and gp130 to preS was assessed by immunoprecipitation with recombinant preS proteins. In patient sera IL‐6 and sIL‐6R concentrations were analysed with respect to the course of hepatitis B infection during and after interferon‐α (IFN‐α) therapy. The IL‐6 and IL‐6 receptor subunits could not be precipitated with recombinant preS proteins. In sera of patients who responded to IFN‐α therapy by virus elimination, a significant increase in sIL‐6R concentration was measured. No increase in sIL‐6R levels was seen in patients who did not respond to IFN‐α. Hence, IL‐6 and IL‐6 receptor subunits do not bind to preS directly. A possible role for sIL‐6R in the elimination of HBV infection is discussed.
Interferon‐α plus amantadine in chronic hepatitis C resistant to interferon alone: a pilot randomized study
Authors: Gaeta G. B. , Stornaiuolo G. , Stanzione M. , Ascione T. , Pasquazzi C. , Taliani G. , Cimino L. , Budillon G. , Piccinino F.
Published: March 2003

The optimal therapy for patients with chronic hepatitis C who have not responded to interferon (IFN) is still an unsolved issue. The aim of this study was to evaluate the efficacy and tolerability of a high dose of IFN‐α2a plus amantadine for chronic hepatitis C patients who were non‐responders to a previous course of IFN.

Forty consecutive patients with chronic hepatitis C, genotype 1b, who had not responded to IFN‐α, were randomized to receive: (i) IFN 4.5 MU daily plus amantadine 200 mg/day for 4 weeks and then IFN 6 MU thrice weekly plus amantadine 200 mg/day for an additional 5 months (group A) or (ii) IFN alone at the same dosage and duration (group B). After 1 month of therapy, normal alanine aminotransferase (ALT) values were observed in three of 21 (14.3%) patients in group A and in three of 19 (15.8%) in group B; serum hepatitis C virus (HCV)‐RNA clearance was observed in one patient (4.8%) in group A and in six (31.6%) in group B. At the end of treatment, six patients (28.6%) in group A and three (15.8%) in group B had normal ALT levels; however, HCV‐RNA in serum was detectable in all of them at levels comparable to the basal values; an ALT relapse occurred within 3 months of stopping therapy. The combination of daily IFN plus amantadine was ineffective in this setting.
Therapeutic management of hepatitis B‐related cirrhosis
Authors: Merle P. , Trepo C.
Published: March 2003

Hepatitis B virus (HBV) infection has a world‐wide distribution, and may lead to cirrhosis, end‐stage liver disease and hepatocellular carcinoma. Therapeutic strategies for HBV cirrhosis are changing rapidly. Treatment with interferon (IFN)‐α may be hazardous and often can only be administered at low doses. The availability of lamivudine has revolutionized the treatment of chronic hepatitis B and opened up new options for the management of patients with decompensated cirrhosis or recurrent hepatitis B post‐liver transplantation. However, lamivudine therapy should be weighed against the risk of selection of resistant mutants and randomized control trials are needed. Hopefully, in the near future, new antiviral drugs such as adefovir dipivoxil which is active on lamivudine‐resistant mutants will become available. IFN‐α is still the only molecule which may prevent HBV‐induced hepatocarcinogenesis in humans. Whether other antivirals will also prove useful warrants further follow‐up studies.
Transmission of hepatitis A through household contact
Authors: Meyerhoff A. S. , Jacobs R. J.
Published: March 2003

In the USA, cost effectiveness assessments support childhood hepatitis A vaccination in geographical areas with elevated disease rates, but not nationally. However, these studies do not address the reduction in disease transmission which may result from routine childhood vaccination. Using decision analysis, we estimated the number and age distribution of secondary hepatitis A cases occurring within households with an index case. Based on the age of the index case, we determined household size and age composition, the proportion of household members susceptible to hepatitis A, the probability of disease transmission, and the likelihood secondarily infected household members would exhibit symptoms. Our model indicates that for every 100 index cases age 6–11 years, 47.2 secondary infections would occur within households, with 23.1 causing overt disease. Lower transmission rates for older index cases reflect smaller household sizes and a higher proportion of household contacts with hepatitis A immunity. When disease transmission rates are applied to a model simulating lifetime risks of hepatitis A, universal vaccination of an annual USA birth cohort is estimated to prevent 24 100 cases of overt disease among household contacts in addition to 71 000 cases among vaccinees. Sensitivity analysis provides a wide range of estimates, but even conservative assumptions suggest routine vaccination would yield an important reduction in secondary cases. Evaluations of hepatitis A prevention should consider the ability of immunization to protect household and other personal contacts.
Determination of hepatitis B virus subtypes by an enzyme immunoassay method using monoclonal antibodies to type‐specific epitopes of HBsAg
Authors: Laperche S. , Girault A. , Beaulieu M. J. , Bouchardeau F. , Couroucé A. M.
Published: March 2003

We described a Hepatitis B surface antigen (HBsAg) subtyping method based on a commercial enzyme immunoassay (EIA) for detection of HBsAg in which the procedure was modified to include the use of monoclonal antibodies with restricted anti‐HBs specificities. This method, which was able to classify HBsAg as: ayw1, ayw2, ayw3, ayw3* (intermediate between ayw3 and ayw4), ayw4, ayr, adw2, adw4 and adr, was compared to counter electrophoresis procedure (CEP) by testing HBsAg positive sera from blood donors included in a prospective national epidemiological survey. Among the 256 HBsAg positive samples tested with both techniques, 111 (43.3%) could not be subtyped with CEP vs 10 (3.9%) with our modified EIA. This difference was related to the serum HBsAg concentration which must be greater than 3000 ng/mL and 100 ng/mL for CEP and EIA, respectively. The results obtained from 145 sera with both methods were concordant. Seventeen out of 18 samples partially classified as ay with CEP were completely determined with EIA.

This reliable procedure, derived from commercially available reagents, can be easily used in several applications such as large epidemiologic studies and as a substitute for nucleotide sequencing genotyping which is not adapted for large‐scale screening and not applicable on samples from nonviremic hepatitis B virus (HBV) carriers.
Quantitative detection of hepatitis B virus DNA in serum by a new rapid real‐time fluorescence PCR assay
Authors: Jardi R. , Rodriguez F. , Buti M. , Costa X. , Cotrina M. , Valdes A. , Galimany R. , Esteban R. , Guardia J.
Published: March 2003

A sensitive and accurate HBV DNA quantification assay is essential for monitoring hepatitis B virus (HBV) replication. This study evaluated a real‐time PCR method performed in the LightCyclerTM analyser for quantitative HBV DNA assay. HBV DNA results with this method were compared with those obtained using a branched‐chain DNA (bDNA) solution hybridization assay. Real‐time PCR was performed using two adjacent fluorescently labelled probes and primers corresponding to the HBV core gene. The same standard employed in the bDNA assay was used for calibration. Serum samples came from 193 HBV surface antigen (HBsAg)‐positive patients (34 HBV e antigen (HBeAg)‐positive and 93 with antibody to HBeAg (anti‐HBe)), and 66 asymptomatic HBV carriers. In addition, we analysed serum samples from 8 anti‐HBe‐positive patients who had been receiving lamivudine treatment for more than three years. A linear standard curve was seen in the range from 103 to 108 copies/mL. In the reproducibility analysis, intra‐assay coefficient of variation (CVs) at two known HBV DNA concentrations were 4% and 2% and interassay CVs were 6% and 4%. The median of serum HBV DNA by real‐time PCR was 9.2 × 108 copies/mL in HBeAg‐positive patients with persistently elevated alanine aminotransferase (ALT) levels, 1.3 × 107 copies/mL in anti‐HBe‐positive cases with persistently elevated ALT levels, 3.7 × 104 copies/mL in anti‐HBe‐positive patients with fluctuating ALT levels and 104 copies/mL in asymptomatic HBV carriers. The differences in HBV DNA levels among the various groups studied were statistically significant (P < 0.05). The cut‐off between chronic hepatitis patients and asymptomatic carriers was found to be at a serum HBV DNA concentration of 5 × 104 copies/mL. Of the 109 serum samples with a viral load < 7.5 × 105 (negative by bDNA assay) 44 (40%) were positive by real‐time PCR: 24 (56%) chronic hepatitis and 20 (33%) asymptomatic carriers. There was a positive association between HBV DNA levels determined by real‐time PCR and ALT levels (P < 0.05), which was not observed with the bDNA assay for HBV DNA quantification. At 12 months of lamivudine treatment, 6 patients (75%) showed HBV DNA levels < 5 × 104 copies/mL (range < 103–2 × 103), significantly lower than at baseline. At 36 months, 2 of 8 (25%) showed HBV DNA levels persistently lower than 5 × 104 copies/mL (1.7 × 103, 6 × 103). The LightCycler quantitative real‐time PCR is a practical, sensitive, reproducible single‐tube assay with a wide dynamic range of detection. The assay is automatic except for DNA extraction and the running time is only 70 min. The LightCycler real‐time PCR is useful for identifying different states of HBV infection and for evaluating the efficacy of viral therapy.
Progressive hepatic fibrosis in healthy carriers of hepatitis C virus with a transaminase breakthrough
Authors: Rumi M. G. , De Filippi F. , Donato M. F. , Del Ninno E. , Colombo M.
Published: March 2003

In short‐term studies, patients with chronic hepatitis C virus (HCV) infection, consistently normal serum aminotransferase (ALT) levels, and minimal or mild necro‐inflammatory changes in the liver, did not progress to histologically severe hepatitis. There are no data on longer term outcome of liver disease in these patients. We describe two patients with HCV infection (genotype 2c) with a rise in serum ALT values greater than 10 times the upper normal value that occurred after an 8‐ and 15‐year period of persistently normal or minimally elevated ALT levels. In both patients, the rise in ALT values lasted more than 16 weeks and was not associated with any symptom or risk factor for acute hepatitis. A liver biopsy performed 4 and 18 months after the ALT flare showed clear‐cut progression from chronic hepatitis with mild activity to chronic hepatitis with severe activity and central to portal septal fibrosis (Ishak score: grading 14 and 6; staging: 4 and 5, respectively). Hence, extended surveillance of HCV carriers with consistently normal or minimally elevated ALT values is warranted as these patients are at risk of ALT flares and may develop progressive liver disease.
Quantitative and functional differences in CD8+ lymphocyte responses in resolved acute and chronic hepatitis C virus infection
Authors: Lancaster T. , Sanders E. , Christie J. M. L. , Brooks C. , Green S. , Rosenberg W. M. C.
Published: March 2003

CD8+ T lymphocyte responses are important in the clearance of viral infections. In chronic infections they may contribute to pathogenesis. To investigate the role of CD8+ T lymphocyte responses in viral clearance and chronic hepatitis C we have compared hepatitis C virus (HCV) specific cytotoxicity and interferon‐gamma (IFN‐γ) production in patients with resolved‐acute, and chronic HCV infection. CD8+ T cell responses to a panel of 13 HCV T cell peptide epitopes were studied using Elispot assays of IFN‐γ production and chromium release cytotoxicity assays. Responses of seven patients with resolved acute HCV infection were compared with those of 14 chronically infected patients. HCV‐specific cytotoxicity differentiated the two populations of patients. The majority (71%) of patients with resolved acute infection tested positive to 42% of relevant peptides compared with the minority (28%) of patients with chronic hepatitis C (P=0.03) who responded to only 8% of relevant peptides (P=0.0009). In contrast, HCV‐specific IFN‐γ production was detected in 86% of patients with either resolved or chronic infection in response to 42% and 35%, respectively, of relevant peptides tested (not significant). In patients with chronic infection the magnitude of the HCV‐specific IFN‐γ production was inversely correlated to viral load (R2=0.52; P=0.042). Failure to clear HCV infection may be attributable to the presence of noncytolytic IFN‐γ producing CD8+ T lymphocytes in chronically infected patients. However these CD8+ T cells may play a beneficial role in contributing to the control of viral load in chronic hepatitis C.
Seroprevalence of hepatitis C markers among intravenous drug users in western European countries: a systematic review
Authors: Matheï C. , Buntinx F. , Damme P. Van
Published: March 2003

Currently, the most important risk factor for hepatitis C virus (HCV) infection in Europe is intravenous drug use. To establish a better insight into the epidemiology of hepatitis C among intravenous drug users (IVDUs) in western European countries a systematic review on the prevalence of hepatitis C markers and their determinants was performed. Reports were identified by searches on Medline and on the internet and by screening reference lists of selected papers. The prevalence rates of anti‐HCV in western European IVDUs reported in the 66 studies selected for analysis, ranged between 37 and 98%. No relation was found between prevalence rates and mean age, mean duration of intravenous drug use, geographical area, setting of the study, method of recruitment or the year(s) of collection of samples. Eleven studies concerning the prevalence of HCV‐RNA in hepatitis C‐infected IVDUs were selected for analysis. Prevalence rates ranged from 26 to 86%. Based on five studies, a statistically significant positive linear relation was found between the mean age of study population and the prevalence of HCV‐RNA. Our analysis revealed considerable variation in prevalence rates of hepatitis C markers among IVDUs in western Europe. We found no conclusive explanation for this variability. Further research investigating the dynamics of the hepatitis C epidemic in IVDUs is necessary.
Prevalence of hepatitis C virus infection in thalassemia and haemodialysis patients in north Iran‐Rasht
Authors: Ansar M. M. , Kooloobandi A.
Published: March 2003

summary. Hepatitis C virus (HCV) seroprevalence and risk factors in north Iran were investigated in 105 thalassemia sufferers, 93 haemodialysis patients and 5976 blood donors by second generation ELISA. Our study showed that haemodialysis patients and thalassemia sufferers were at higher risk of having HCV infection; the prevalence being 55.9% and 63.8% respectively in comparison to the prevalence of blood donors (0.5%). A confirmatory immunoblotting was employed using HCV‐positive cases (54 thalassemia sufferers and 19 blood donors). The result showed that 92.6% of samples of the first group and 10.5% of the latter were positive. Thus, it can be suggested that ELISA in low‐risk cases may produce considerable false positives. In HCV‐positive patients with thalassemia, the incidence of HCV among different age groups and genders was similar but a strong correlation in respect to the number of blood transfusion (P=0.008) was observed. In HCV‐positive haemodialysis patients, it was found that there was no correlation with liver function tests (alanine aminotransferase and aspartate aminotransferase: ALT and AST), but a significant correlation was observed in respect to the duration of dialysis(P=0.000) and the number of units transfused (P=0.000). Consequently, it still seems blood transfusion is the main factor for increasing the incidence of HCV in thalassemia sufferers and haemodialysis patients.
Induction therapy with consensus interferon (CIFN) does not improve sustained virologic response in chronic hepatitis C
Authors: Layden Thomas J. , Layden Jennifer E. , Reddy K. Rajender , Levy‐Drummer Rachel S. , Poulakos Jennifer , Neumann Avidan U.
Published: March 2003

summary. In patients infected with hepatitis C virus (HCV) genotype 1, sustained viral response (SVR) averages 10–40% depending on treatment regime. It has been proposed that high dose daily interferon (IFN) therapy early in therapy (induction dosing) may enhance SVR. In the present study we examined this issue and also assessed whether one could predict SVR and non‐SVR, based on viral kinetics during the first month of induction therapy. End of treatment response and SVR was determined in 173 HCV infected patients who were treated with different induction doses of consensus interferon (CIFN) for one month followed by 11 months of standard 9 µg of CIFN thrice weekly (TIW). The second phase decline slope was calculated by log‐linear regression on weekly measurements of serum HCV RNA during the first 7–28 days of treatment; rapid viral response (RVR) during the first month of induction dosing was defined as a decline of > 0.3 log copies/mL/week. Overall, SVR occurred in 11% of genotype 1 infected patients and 41% of patients with nongenotype 1. High dose induction therapy did not increase the rate of SVR, in either genotype 1 or genotype 2/3 infected patients. No patient without a RVR during the first month had SVR, while SVR occurred in 55% of the patients with RVR. RVR was the best predictor of SVR using multivariate analysis. These results indicate that induction dosing with CIFN does not improve SVR rates. They also suggest that early viral kinetics during the first month of therapy can predict non‐SVR and thus save a patient a year long treatment which is fraught with side‐effects and significant cost.
Adoptive transfer of donor‐derived immunity by liver transplantation: a potential avenue to prevent hepatitis B virus reinfection
Authors: Dahmen U. , Li J. , Dirsch O. , Gu Y. L. , Polywka S. , Doebel L. , Shen K. , Broelsch C. E.
Published: March 2003

summary. Immunity to hepatitis B has been successfully transferred by bone marrow transplantation, but has also occurred after liver transplantation (LTx). This study was designed to analyse the influence of alloreactivity and immunosuppression, on the efficacy of adoptive immune transfer to hepatitis B by liver transplantation. Orthotopic LTx (n = 34) were performed in three rat strain combinations representing different genetic constellations. Donors had been vaccinated twice with recombinant hepatitis B surface antigen while recipients were unimmunized. Half of the allogeneic recipients were immunosuppressed with cyclosporin A. All animals were monitored weekly for the presence of anti‐hepatitis B surface antibodies (anti‐HBs). Effective anti‐HBs titres were detected in 85% (29/34) of liver recipients and lasted from 2 to 10 weeks. Donor titre above >15 000 mIU/mL ensured a 100% seroconversion rate in the recipients. The maximal anti‐HBs titre in recipients represented 0.06% ∼ 0.76% of the donor titre. Rejection reduced the adoptive immune transfer, which was protected by immunosuppression. These observations suggest that transfer of functionally active donor lymphocytes, deriving from the graft, contributed to the donor‐derived immune response in the recipient. Further studies to augment the donor‐derived immune response are warranted to ensure a therapeutic effect for the recipient at risk of reinfection.
Distribution and status of the Red Squirrel (Sciurus vulgaris) and Grey Squirrel (Sciurus carolinensis) in Ireland
Authors: Teangana D. Ó. , Reilly S. , Montgomery W. I. , Rochford J.
Published: March 2003

The distributions of the Red and Grey Squirrel were surveyed in Northern Ireland and the Republic of Ireland between 1994 and 1996. Survey methods differed between the two studies. In the former, all suitable habitat, of at least 15 ha, was inspected for species presence or absence. In the Republic, data were gathered through questionnaires to governmental and independent wildlife bodies. The combined results indicate that the Red Squirrel remains widespread and locally abundant, and is present in all but two counties. The Grey Squirrel is now more widespread than ever before, and can be found in 22 of the 32 counties. Its range expansion has varied from 0 km/yr to an estimated 13.4 km/yr, as various geographical features, principally rivers, have hindered its progress in certain directions.
Road verges as habitat for small mammals in Britain
Authors: Bellamy P. E. , Shore R. F. , Ardeshir D. , Treweek J. R. , Sparks T. H.
Published: March 2003

There are 370 000 kilometres of roads in Great Britain, mostly bordered by a verge that is potential habitat for small mammals. The present study assessed the importance of road verges as small mammal habitat and investigated the influence of some key features on rodent abundance. Five rodent and three shrew species were live‐trapped on 14 road verges in late summer 1994 and nine verges in autumn 1996 in north Cambridgeshire, UK. On average, between three and four species were captured per verge. Bank Voles Clethrionomys glareolus, Wood Mice Apodemus sylvaticus and Field Voles Microtus agrestis were the most abundant species, with mean densities of 45.5, 40.2 and 29.5 animals km–1 in summer and 52.8, 181.9 and 47.2 animals km–1 in autumn. Numbers varied between verges and this was significantly correlated with particular features on the verge. Bank Vole and Field Vole numbers showed a significant positive correlation with the dimensions of hedges and the width of the tall grass area, respectively. Wood Mice were also more numerous on verges with big hedges but the relationship between mouse abundance and verge structure was complex. The number of mice in 1994 was positively and significantly correlated with hedge features and with the width of the short grass sightline, whereas, in autumn 1996, they were only significantly correlated with total verge width (positive association) and ditch width (negative association).
Coprophagy in leporids and other mammalian herbivores
Authors: Hirakawa Hirofumi
Published: March 2003

Leporids have long been known to reingest soft faeces. However, it was recently found that they regularly reingest hard faeces, too. During the daytime, both soft and hard faeces are defecated and all of the faeces are reingested. Excreted at night are the hard faeces, which are normally discarded but reingested in starvation. The separation mechanism in the proximal colon, which diverts fine particles into the caecum and thus only passes large food particles, produces hard faeces. When the mechanism ceases acting, fermented caecal materials are excreted as soft faeces. The reingestion of soft faeces, rich in vitamins and microbial proteins, is physiologically imperative. Hard faeces are basically a refuse, but their thorough mastication at reingestion reduces poorly digestible large particles to fine ones good for fermentation. The regular reingestion of daytime hard faeces thus promotes food digestibility. The temporary use of night‐time hard faeces allows leporids to do without food for some time. It thus gives leporids behavioural flexibility and thereby an ecological advantage. Reingestion is also known in other small‐ to medium‐sized herbivores, which are all caecal fermenters. Morphological differentiation between faeces is reported only in larger species, but all ingested faeces are found to be richer in nutrients than discarded ones. Thus a separation mechanism is probably present in all reingesting species. Reingestion activity is deeply related to other behavioural and physiological traits of small mammalian herbivores, hence its study is important to understanding of their ecology and biology. Leporids are the largest of the reingesting species except for the semi‐aquatic Coypu, and reingestion by leporids is certainly the most sophisticated. This development of a reingestion‐involved digestive system has probably brought them to their present niche, as terrestrial medium‐sized generalist mammalian herbivores, and consequently made their characteristic hide‐and‐run lifeforms by exposing them to a strong predation pressure.
Geographical distribution and habitat occurrence of the Water Shrew (Neomys fodiens) in the Weald of South‐East England
Authors: Greenwood A. , Churchfield S. , Hickey C.
Published: March 2003

A survey of 96 sites in a range of riparian habitats in the catchments of five rivers during June–August 1998 used the bait tube method to investigate the geographical distribution and habitat occurrence of Water Shrews (Neomys fodiens) in the Weald of South‐East England. Water Shrews were found at 42% of sites, and were widely distributed in all river catchments except the Mole. They occurred in many riparian habitats, including rivers, streams, canals and ditches, with a range of physical and biotic characteristics. There were no signs of habitat avoidance in response to human disturbance but Water Shrews were absent from the river catchment with lowest water quality. Logistic regression analysis was used to model the effect of habitat variables on the presence of Water Shrews, with current speed, water depth, bank incline and bank‐side vegetation identified as important variables. Fast‐flowing shallow waters had a significant positive effect on their presence, whereas scarce herbaceous vegetation and a bank of low incline had a significant negative effect. These habitat variables appear to be reliable indicators of the probability of finding Water Shrews at a particular site, and have implications for habitat management and conservation.
Alary polymorphism in Triatoma spinolai and its possible relationship with demographic strategy
Authors: SCHOFIELD  , APT  , SAGUA  , PANZERA  , DUJARDIN
Published: March 2003

Among collections of Triatoma spinolai from various sites in northern Chile, adults from coastal populations are invariably wingless, whereas inland populations show balanced alary polymorphism between wingless females and males that are either winged or wingless. Laboratory crosses showed that male offspring from normal‐winged parents were always winged (88% long‐winged) and those from long‐winged male parents were all long‐winged. The male offspring from wingless males always included winged males: 11/33 = 33%, of which 8/11 = 73% were long‐winged. An X‐linked mutation is proposed to inhibit wing development. Field studies of population demography indicate that male alary polymorphism is advantageous in the desert environment of northern Chile.
Distribution of Borrelia burgdorferi s.l. spirochaete DNA in British ticks (Argasidae and Ixodidae) since the 19th Century, assessed by PCR
Authors: HUBBARD, MARK J. , BAKER ANNE S. , CANN KATHRYN J.
Published: March 2003

The distribution of Borrelia burgdorferi sensu lato, the Lyme borreliosis agent, was surveyed in British ticks in the collection of the Natural History Museum, London. Alcohol‐preserved specimens of eight species of ticks known to attack humans were studied: Ixodes ricinus, I. hexagonus, I. uriae, I. trianguliceps, Dermacentor reticulatus, Haemaphysalis punctata, Rhipicephalus sanguineus and Argas vespertilionis. The sample comprised all life stages and originated from a wide range of host species, collection dates (1896–1994) and geographical localities in England, Scotland and Wales.

Borrelia burgdorferi s. l. DNA, detected by a polymerase chain reaction that targeted the outer surface protein A gene, was found in all eight species. The overall proportion of PCR‐positive specimens ranged from 7.8% for I. hexagonus (mostly from mustelids and hedgehogs) to 98.3% for I. uriae (mostly from seabirds). Borrelia burgdorferi s. l. DNA was found for the first time in the bat parasite A. vespertilionis (85.3%). The spirochaete is newly recorded in British populations of I. trianguliceps (97.4%, mostly from voles, mice and shrews), D. reticulatus (12.5% from dog and man) and R. sanguineus (30% from dogs and human dwellings). Of the four tick species with larvae available for testing, examples of I. ricinus, I. uriae and A. vespertilionis were PCR positive, as were significantly more nymphs than adults of I. ricinus, I. hexagonus and A. vespertilionis. Analyses showed that B. burgdorferi s. l. has been consistently present in British tick populations since at least 1897. Ticks positive for B. burgdorferi s. l. DNA were collected in all months of the year, throughout Britain, and were found on a wide range of mammal and bird species. PCR positivity does not prove vector or reservoir competence, but the use of archived material has demonstrated an extensive range of host–tick relationships involving B. burgdorferi s.l. in Britain for >100 years.
Increasing parasitism by the German yellow jacket wasp, Paravespula germanica, on dairy cattle in Israel
Authors: BRAVERMAN
Published: March 2003

During the past two decades, parasitism by the German yellow jacket wasp, Paravespula germanica, on lactating dairy cattle has occurred in Israel during August to October annually, affecting up to 65% of cows in certain herds. The nibbled and exposed tissues of teats and sometimes udders become infested by bacteria, especially Streptococcus dysgalactiae and Actinomyces pyogenes, causing clinical and subclinical mastitis. Normally, German wasps are primarily insect predators, but the urbanization around many dairy farms has reduced open space and associated standard food sources, i.e. insects, plants and carcasses. This has resulted in P. germanica nesting more often on dairy farms. In some instances, when high densities of P. germanica correspond with scarcity of prey, a segment of the wasp population preys primarily on the older and heavier cows with weak defensive behaviour. The teat feeding colonies of P. germanica may have an advantage, in that they are less dependent on fluctuations in the number of prey insects.
Mechanical transmission ofTrypanosoma evansiandT. congolensebyStomoxys nigerandS. taeniatusin a laboratory mouse model
Authors: Sumba A. Leunita , Mihok Steve , Oyieke Florence A.
Published: March 2003

Abstract.Mechanical transmission of Trypanosoma evansi (South American origin) and T. congolense of Kilifi DNA type (Kenyan origin) was studied in laboratory mice using the African stable flies Stomoxys niger niger and S. taeniatus. Altogether, 355 flies were interrupted after feeding on infected blood and then transferred immediately to an uninfected mouse to complete feeding. Microscopy and subinoculation of triturated flies into uninfected mice demonstrated the survival of T. congolense in Stomoxys for up to 210 min and T. evansi for up to 480 min. Parasites survived for much longer periods in the digestive tract than inside or on the mouthparts. Trypanosoma congolense was transmitted only by S. n. niger, and only at low rates of 3, 8 and 10% using flies of different feeding histories: fed on blood the previous day, freshly caught, and teneral. Trypanosoma evansi was transmitted by both Stomoxys species at higher rates: S. taeniatus range 13–18%;S. n. niger range 17–35%. The highest transmission rate occurred with the combination of teneral S. n. niger and T. evansi.
Distribution of the Simulium metallicum complex in Mexico in relation to selected environmental variables
Authors: Millest A. L. , Cheke R. A. , Greenwood R.
Published: March 2003

Larvae of the Simulium metallicum complex (Diptera: Simuliidae) were collected from three foci of human onchocerciasis in Mexico. Specimens were separated into five different cytotypes, identified by morphological characteristics (head pattern and body colour) or polytene chromosome features. Differences were found between foci in the cytotype composition of the S.metallicum complex. Nearly all specimens were cytotype A in the Chamula (97%) and Soconusco (86%) foci. In the Oaxaca focus, however, cytotype I predominated (63%) with 14% cytotype A. Cytotype I comprised only 6% of specimens in the Soconusco focus and was very rare in the Chamula focus. Cytotypes B and H occurred only rarely in all three foci. Cytotype X was found only in Oaxaca. Environmental variables were measured at the collection sites and canonical correspondence analysis (CCA) was used to investigate the associations of cytotype distributions with the following factors: stream size, amount of shade, water clarity, pH, temperature and altitude. Members of the S.metallicum species complex were found to be differentially distributed according to stream conditions and there was a significant correlation between their distributions and the environmental variables. The most important factor in canonical axis 1 of the CCA was pH (t‐value –4.38) with temperature (–2.48) and altitude (2.19) having some influence, but the other variables were unimportant. In the second canonical axis, pH (–3.52) was the only variable having a significant effect. Thus, cytotype A was associated with high pH, high temperature and low altitude; B was associated with similar sites but with higher temperatures and at lower average elevations. Cytotype H was found at the centres of the ranges of these variables, I at sites with the lowest temperatures and highest altitudes and X in rivers with the lowest pH.
Effects of permethrin at different temperatures on pyrethroid‐resistant and susceptible strains of Anopheles
Authors: Hodjati M. H. , Curtis C. F.
Published: March 2003

The influence of temperature (16, 22, 28, 37°C) on effects of permethrin was investigated for susceptible and pyrethroid‐resistant strains of the mosquitoes Anopheles gambiae and An. stephensi (Diptera: Culicidae). Young unfed female adult mosquitoes were exposed to 0.25% permethrin test papers or to polyester netting treated with permethrin 500 mg a.i./m2. The time to 50% knock‐down (KT50) declined as temperature increased, i.e. there was a positive temperature coefficient of this effect of the pyrethroid. Resistance ratios (comparing KT50 values) between resistant and susceptible An. stephensi ranged between 2.5 and 4.4 at the different temperatures. Comparative tests of pyrethroid tolerance of different strains would be valid over the 22–28°C range but, when using a discriminating dose to detect resistance, more precise temperature control is desirable.

Mortality 24 h after exposure to 0.25% permethrin of both susceptible and resistant strains of An. stephensi showed a negative correlation with temperature between 16 and 22°C and a positive correlation at higher temperatures. In An. gambiae, however, the correlation was positive over the whole range.

Irritancy of permethrin‐treated netting to Anopheles females (measured as time lapse until first flight take‐off, and the number of take‐offs during 7.5 min exposure) was positively correlated with temperature in all four strains and was much greater for the susceptible than the resistant strains.
IgG responses to salivary gland extract of Ixodes ricinus ticks vary inversely with resistance in naturally exposed sheep
Authors: Ogden N. H. , Casey A. N. J. , Lawrie C. H. , French N. P. , Woldehiwet Z. , Carter S. D.
Published: March 2003

Abstract Enzyme‐linked immunosorbent assay (ELISA) was used to investigate the antibody responses of control sheep, and sheep naturally exposed to Ixodes ricinus Linné (Acari: Ixodidae) ticks, to salivary gland extract (SGE) proteins of partially fed, adult I. ricinus. Comparisons between responses of control sheep and naturally infested sheep by Western blot analysis suggested that variations in IgG responses of I. ricinus‐exposed sheep were mostly associated with specific responses to I. ricinus SGE antigens. Sheep IgG responses were positively related to the numbers of adult ticks feeding per sheep at the time samples were collected, were greater during the spring than the autumn periods of I. ricinus activity and were inversely related to sheep resistance to ticks measured by the weights of nymphal I. ricinus that engorged on the sheep. These findings suggest that sheep lose their resistance to ticks due to polarization of a Th1 type response to some tick antigens towards a Th2 type response when sheep are exposed to high, natural tick infestations, or to seasonal conditions of relative nutritional stress. Potential consequences for the epidemiology of tick‐borne diseases are discussed.
Assessment of rDNA IGS as a molecular marker in the Simulium damnosum complex
Authors: Morales‐Hojas R. , Post R. J. , Cheke R. A. , Wilson M. D.
Published: March 2003

Abstract For five cytospecies of the Simulium damnosum Theobald complex of blackflies (Diptera: Simuliidae) from West Africa, both ends of the intergenic spacer region (IGS) of the rDNA have been sequenced with the aim of developing specific molecular markers. No specific differences in these two regions were detected between Simulium sanctipauli V. & D., Simulium sirbanum V. & D., Simulium soubrense V. & D., Simulium squamosum Enderlein and Simulium yahense V. & D., except in the number of A subrepeats at the 5′ end of the IGS (two in S. squamosum and four or five in the others) and in position 310 of the 3′ end (a C in S. squamosum and a G in the others). However, genetic distances within and between species overlapped. These DNA sequences had no strong phylogenetic signal, and the trees obtained were mostly unresolved. Although most sequences from S. squamosum clustered together, a few of them were more similar to those in other cytospecies. These results could be explained either by hybridization with genetic introgression or by ancestral polymorphism and recent speciation.
The development of a questionnaire to assess the readiness of health care students for interprofessional learning (RIPLS)
Authors: Parsell Glennys , Bligh John
Published: March 2003

Objectives

Although shared learning activities are gradually being introduced to health care undergraduates, it has not been possible to measure the effects of educational interventions on students' attitudes. The main objective of this study was to develop a rating scale using items based on the desired outcomes of shared learning, to assess the `readiness' of health care students for shared learning activities.

Design and participants

A questionnaire study of 120 undergraduate students in 8 health care professions.

Results

Principal components analysis resulted a 3‐ factor scale with 19 items and having an internal consistency of 0.9. The factors have been initially named `team‐working and collaboration', `professional identity' and `professional roles'.

Conclusions

The new scale may be used to explore differences in students' perception and attitudes towards multi‐professional learning. Further work is necessary to validate the scale amongst a larger population.
Visiting elective students at the University of Toronto from the Korea University Medical College
Authors: Ahn
Published: March 2003

Objectives

The main goal of the international elective programme was to provide the Korean students with a cross‐cultural educational environment.

Design

This programme was carried out on a voluntary basis during the summer vacation, rotating students through various clinical divisions in the teaching hospital.

Setting

The University of Toronto.

Subjects

Medical students from the Korea University Medical College.

Results

The students found the student–teacher relationship to be much more open and liberal. Due to a different curricular structure, the Canadians have better clinical skills and problem‐solving abilities in real clinical settings. The cultural differences perceived by the students during the elective programme led them to believe that educational reform in Korea imperatively requires curricular change, but more importantly, a change in our traditional psychological and behavioural traits which derive from Confucianism.

Conclusions

Extreme politeness, passiveness and blind respect for teachers, which are encouraged by Confucianism, are not effective in higher education. All the elective students, as well as the Canadian preceptors, believe that this programme is an invaluable asset.
Use of learning contracts in an office‐based primary care clerkship
Authors: McDermott Mary McGrae , Curry Raymond H , Stille F Conrad , Martin Gary J
Published: March 2003

Objectives

This paper describes implementation of the learner‐centred learning goal within the primary care clerkship at a Midwestern, United States medical school.

Design

The learner‐centred learning goal exercise was developed to tailor students' educational activities to their personal level of development and to enhance their commitment to life‐long learning in medicine. In the learner‐centred learning goal exercise, each student records three specific learning goals early in the primary care clerkship. Students record the methods by which they will pursue and document achievement of each goal. Attainment of the learner‐centred learning goal is evaluated based on an oral presentation at the end of the clerkship. We compiled presented learning goals along with the corresponding grade. Students' ratings of the learner‐centred learning goal exercise were also compiled. Evaluations and ratings were made on a 1–5 Likert scale, where 1 is the best rating and 5 is worst.

Setting

Department of Medicine, Northwestern University Medical School, Chicago, USA.

Subjects

One hundred and seventy‐seven third‐ and fourth‐year medical students who presented learner‐centred learning goals between 1 July 1995 and 30 June 1996.

Results

Students rated pursuing their individual learning goals more worthwhile than most clerkship lectures but less worthwhile than the office experience. Several learning goals were chosen by a disproportionate number of students, potentially indicative of some perceived deficiencies elsewhere in the curriculum. Third‐year students ranked the learner‐centred learning goal exercise more favourably than fourth‐year students (2·14 vs. 2·51, P = 0·03).

Conclusions

The learner‐centred learning goal exercise is a feasible and well‐received method within our primary care clerkship. Further study is required to determine whether the exercise promotes independent learning after formal medical school education is completed.
Migration/selection balance and ecotypic differentiation in the mosquito Culex pipiens
Authors: CHEVILLON C. , RIVET Y. , RAYMOND M. , ROUSSET F. , SMOUSE P. E. , PASTEUR N.
Published: March 2003

Ecotypic differentiation is well described in the mosquito Culex pipiens, separating populations breeding in subterranean and human‐made sites (hypogeous habitat) from those in open‐air sites (epigeous habitat). The pattern of population differentiation observed at the Aat‐1 locus has been suspected to be associated with such ecotypic differentiation via habitat‐dependent selection, but this supposition is still the subject of debate in the literature. We analysed differentiation patterns for Aat‐1 and another four loci among populations from both habitat types in the French Alps. We showed that the Aat‐1A allele is favoured within hypogeous habitats but selected against within epigeous habitats. Comparisons of our results with other data reported in the literature indicate that the Aat‐1A allele is generally evolving under habitat‐differential selection, but that the precise balance of migration and selection that determines equilibrium allele frequencies varies greatly across Europe. The nature of this habitat‐dependent selection, and its resulting (geographically varying) equilibrium point, are discussed in relation to the biology of this mosquito species.
Genetic identification of asteroid larvae from Tasmania, Australia, by PCR–RFLP
Authors: EVANS B. S. , WHITE R. W. G. , WARD R. D.
Published: March 2003

Studies of seastar larvae in the Derwent River (Tasmania) were hampered by identification uncertainties. A genetic test was developed, based on PCR amplification of a 1300 bp mitochondrial DNA region followed by digestion with three restriction enzymes. The restriction profiles of adults of 14 seastar species were determined. The test was validated for larvae as laboratory‐raised larvae of two species had the appropriate composite haplotypes. Approximately 80% of planktotrophic seastar larvae from Derwent River plankton samples were identified as the recently introduced northern Pacific seastar, Asterias amurensis. The two other larval seastars identified were Coscinasterias muricata and Patiriella regularis.
The application of RAPD markers in stock discrimination of the four‐wing flyingfish, Hirundichthys affinis in the central western Atlantic
Authors: GOMES CHARMAINE , DALES RICHARD B. G. , OXENFORD HAZEL A.
Published: March 2003

The polymerase chain reaction–random amplified polymorphic DNA (PCR–RAPD) technique was used to examine genetic variability and population structuring in the four‐wing flyingfish, Hirundichthys affinis within the central western Atlantic. Three random decamer primers and pairs of these primers were used to amplify nuclear DNA from 360 fish sampled from six populations (at five locations) across the region. A total of 58 polymorphic RAPD markers were identified, 20 of which were population‐specific and six of which were subregional or stock‐specific markers. Cluster analysis of similarity indices indicated the presence of three genetically distinct subregional stocks located in the eastern Caribbean, southern Netherlands Antilles and Brazil, respectively. Estimates of gene diversity (φ) and gene flow (Nm) are consistent with this three‐stock hypothesis. Furthermore, partially restricted gene flow was apparent among spatially and temporally separate sampled populations within the eastern Caribbean subregional stock, indicating the possible presence of different spawning groups. These results are entirely consistent with those obtained from PCR–RFLP analysis of the mtDNA D‐loop in the same fish, indicating the presence of barriers to dispersal and interbreeding in both sexes. We conclude that the PCR–RAPD technique is suitable for determining population stock structure in this species and that a three‐stock approach to managing H. affinis within the central western Atlantic would be appropriate.