bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiological and ecological characteristics of past dengue virus infection in Santa Clara, Peru
Authors: Reiskind Michael H. , Baisley Kathy J. , Calampa Carlos , Sharp Trueman W. , Watts Douglas M. , Wilson Mark L.
Published: March 2003

To determine risk factors associated with dengue (DEN) virus infection among residents of Santa Clara, Peru, a rural Amazonian village near Iquitos, a cross‐sectional serological, epidemiological and environmental survey was conducted. Demographic, social and behavioural information was obtained by standardized questionnaire from 1225 Santa Clara residents (61.3%) aged 5 years or older. Additional data were obtained on the environmental variables and immature mosquito species and abundance surrounding each household (n=248). Sera that had been collected previously by the Peruvian Ministry of Health from residents were tested by an enzyme‐linked immunosorbent assay (ELISA) for DEN virus IgG antibody. Antibody identity was verified as DEN by plaque reduction neutralization test. Data on individuals were analysed by univariate and multivariable methods, and independent sample t‐tests. Spatial clustering was evaluated by comparing distances among DEN positive households. Overall, antibody prevalence was 29.4% and more than doubled from the youngest to the oldest age groups, but did not differ by sex. Curiously, length of residence in Santa Clara was negatively associated with DEN virus antibodies. More frequent travel to Iquitos was positively associated with seroprevalence. Residents who obtained water from a river source rather than a local well also had significantly higher antibody prevalence. None of the environmental variables measured at each household corresponded to the patterns of antibody distribution. Of the larval mosquitoes found around residences, all were determined to be species other than Aedes. No evidence of spatial autocorrelation among antibody‐positive households was detected. These results strongly suggested that recent DEN virus transmission did not occur in the village and that most infections of residents of this rural village were acquired while visiting the city of Iquitos.
Molecular characterization of field isolates of human pathogenic trypanosomes
Authors: Gibson Wendy
Published: March 2003

The accurate identification of each of the three subspecies of Trypanosoma brucei remains a challenging problem in the epidemiology of sleeping sickness. Advances in molecular characterization have revealed a much greater degree of heterogeneity within the species than previously supposed. Only group 1 T. b. gambiense stands out as a separate entity, defined by several molecular markers. T. b. rhodesiense is generally too similar to sympatric T. b. brucei strains to be distinguished from them by any particular molecular markers. Nevertheless, characterization of trypanosome isolates from humans and other animals has allowed the identification of potential reservoir hosts of T. b. rhodesiense. The recent discovery of a gene for human serum resistance may provide a useful marker for T. b. rhodesiense in the future. There have been few attempts to find associations between genetic markers and other biological characters, except human infectivity. However, virulence or fly transmissibility have been correlated with molecular markers in some instances.
Tungiasis: a neglected health problem of poor communities
Authors: Heukelbach Jörg , De Oliveira Fabíola Araújo Sales , Hesse Gerhard , Feldmeier Hermann
Published: March 2003

Tungiasis is caused by the flea Tunga penetrans. Growing urbanization, improved housing and use of appropriate footwear presumably have led to an overall reduction of the occurrence of this ectoparasitosis within the last decades. However, it is still highly prevalent where people live in extreme poverty, occurring in many Latin American and African countries. Although the infection has long been known, data on the ectoparasite’s biology and the epidemiology of the disease are scant. Methods for treatment, prevention and control have never been evaluated in a scientific manner. Tungiasis remains an important public health problem for the very poor, a problem neglected by those who are affected, by the medical profession and by the scientific community.
The influence of prematurity and low birthweight on transplacental antibody transfer in a rural West African population
Authors: Okoko J. B. , Wesumperuma H. L. , Hart C. A.
Published: March 2003

OBJECTIVE To determine the influence of prematurity and low birthweight (LBW) on transplacental antibody transfer.

METHOD In a physician‐blinded, cross‐sectional study of 213 mother–baby pairs in the labour ward of Bansang Hospital, The Gambia, paired maternal and cord serum samples were tested for specific IgG antibody titres for measles virus (MeV), herpes simplex virus type 1 (HSV1), respiratory syncytial virus (RSV), varicella‐zoster virus (VZV), tetanus toxoid (TT) and diphtheria toxoid (DT) antigens using enzyme linked immunosorbent assay (ELISA).

RESULTS Prematurity was significantly associated with reduced placental antibody transfer for MeV, HSV1, TT, DT, RSV and VZV. Maternal antibody transfer for MeV, HSV1, TT, DT, RSV and VZV was significantly lower in neonates with LBW than in babies with adequate birthweight (ABW).

CONCLUSION Materno–foetal transfer of antibodies is impaired in prematurity and LBW babies in this Gambian population. Reduction in antibody transfer may further predispose these already vulnerable neonates to bacteria and viral infections. Therefore, alternative vaccination strategies, including earlier vaccination schedules, are needed to provide better protection to these young infants.
Somatostatin and intestinal schistosomiasis: therapeutic and neuropathological implications in host–parasite interactions
Authors: Chatterjee Shyama , De Man Joris , Van Marck Eric
Published: March 2003

A better insight into the mechanisms regulating the human body can lead to improved knowledge of the patho‐physiological processes of many diseases. New therapeutic possibilities can be devised at the level of these regulatory mechanisms. Somatostatin is one of the major regulatory hormones in the central nervous system (CNS) and digestive system. Its wide variety of activities means it is implicated in a broad range of conditions. One symptom common to both the acute and chronic stages of schistosomiasis is intestinal pathology characterized by abdominal pain, diarrhoea that is bloody in more chronic stages, nausea and fever. Some chronic patients develop severe hepatosplenic fibrosis, leading to fatal oesophageal variceal bleeding. In this review we assess the therapeutic potential of somatostatin in the treatment of intestinal pathology associated with schistosomiasis. The activity of somatostatin is mediated via binding to specific cell surface receptors. While we are making progress in studies of the expression and regulation of the different somatostatin receptors, the true role and distribution of each receptor subtype is far from fully understood. Animal models will help to define the specific role of individual receptors in physiological and pathological conditions. The regulation of receptor expression as well as receptor internalization can give us insight into the effect of exogenous somatostatin on schistosomiasis‐mediated intestinal pathology, as well as its modulation by intrinsically produced somatostatin levels.
Availability and affordability of treatment for Human African Trypanosomiasis
Authors: Etchegorry M. Gastellu , Helenport J. P. , Pecoul B. , Jannin J. , Legros D.
Published: March 2003

Human African Trypanosomiasis (HAT) is a re‐emerging disease whose usual treatments are becoming less efficient because of the increasing parasite resistance. Availability of HAT drugs is poor and their production in danger because of technical, ecological and economic constraints. In view of this dramatic situation, a network involving experts from NGOs, WHO and pharmaceutical producers was commissioned with updating estimates of need for each HAT drug for the coming years; negotiations with potential producers of new drugs such as eflornithine; securing sustainable manufacturing of existing drugs; clinical research into new combinations of these drugs for first and second‐line treatments; centralizing drug purchases and their distribution through a unique non‐profit entity; and addressing regulatory and legal issues concerning new drugs.
Is Rhodnius robustus (Hemiptera: Reduviidae) responsible for Chagas disease transmission in Western Venezuela?
Authors: Feliciangeli M. Dora , Dujardin Jean‐Pierre , Bastrenta Brigitte , Mazzarri Milena , Villegas Judith , Flores Maria , Muñoz Maruska
Published: March 2003

We present evidence for the putative role of Rhodnius robustus as extradomestic vector of Chagas disease in Western Venezuela. First, we assessed the validity of this triatomine species by genetic characterization in relation with some other species of the prolixus group. Random amplified polymorphic DNA data showed a clear separation between this species and R. prolixus and indicated a probable genetic heterogeneity within R. robustus. Faeces and gut contents were microscopically examined in 54 of 137 R. robustus collected in palm trees. According to this morphological examination, 18% were positive for Trypanosoma cruzi, 11% harboured T. rangeli and 11% showed mixed infection. Five of the seven samples examined gave a polymerase chain reaction major band of 270 bp specific of T. cruzi. The hybridization probes showed that R. robustus may transmit clones 20 and 39 (or genetically related ones) in Venezuela. Such a transmission might occur when, in absence of domestic R. prolixus and attracted by artificial light, R. robustus enters houses and feeds on humans, or when people are bitten outdoors. The lack of bugs inside houses could mean that the insects leave houses after feeding, or die without reproducing there.
Wide distribution of Plasmodium ovale in Myanmar
Authors: Win T. T. , Lin K. , Mizuno S. , Zhou M. , Liu Q. , Ferreira M. U. , Tantular I. S. , Kojima S. , Ishii A. , Kawamoto F.
Published: March 2003

The presence of Plasmodium ovale has never been previously reported in Myanmar. Using blood samples obtained in many villages across the country between 1996 and 2000, molecular diagnosis of Plasmodium species was made with semi‐ or full‐nested polymerase chain reaction (PCR) with species‐specific primers, followed by agarose gel electrophoresis to detect amplification products. The presence of P. ovale was also confirmed with the another PCR‐based diagnosis, the microtiterplate hybridization (MPH) method using species‐specific probes. Both methods target the A type of the small subunit ribosomal RNA gene of the four human malaria parasites. Plasmodium ovale DNA was amplified in samples from 65 (4.9%) of 1323 PCR‐positive patients, with perfect agreement between results obtained by nested PCR and MPH. Only four P. ovale‐infected patients had single‐species infection; all others were coinfected with P. falciparum, P. vivax and/or P. malariae. Quadruple infections were observed in six subjects. Parasites with typical P. ovale morphology were found in only 19 patients by conventional microscopy of Giemsa‐stained thin smears or fluorescence microscopy of acridine orange‐stained thin smears. Plasmodium ovale infections were found in villages situated in the southern, central and western regions of Myanmar, suggesting that P. ovale may be widely distributed in this country.
Malaria prevention in highland Kenya: indoor residual house‐spraying vs. insecticide‐treated bednets
Authors: Guyatt Helen L. , Corlett Sarah K. , Robinson Timothy P. , Ochola Sam A. , Snow Robert W.
Published: March 2003

This study compares the effectiveness and cost‐effectiveness of indoor residual house‐spraying (IRS) and insecticide‐treated bednets (ITNs) against infection with Plasmodium falciparum as part of malaria control in the highlands of western Kenya. Homesteads operationally targeted for IRS and ITNs during a district‐based emergency response undertaken by an international relief agency were selected at random for evaluation. Five hundred and ninety homesteads were selected (200 with no vector control, 200 with IRS and 190 with ITNs). In July 2000, residents in these homesteads were randomly sampled according to three age‐groups: 6 months–4 years, 5–15 years, and > 15 years for the presence of P. falciparum antigen (Pf HRP‐2) using the rapid whole blood immunochromatographic test (ICT). The prevalence of P. falciparum infection amongst household members not protected by either IRS or ITN was 13%. Sleeping under a treated bednet reduced the risk of infection by 63% (58–68%) and sleeping in a room sprayed with insecticide reduced the risk by 75% (73–76%). The economic cost per infection case prevented by IRS was US$ 9 compared to US$ 29 for ITNs. This study suggests that IRS may be both more effective and cheaper than ITNs in communities subjected to low, seasonal risks of infection and as such should be considered as part of the control armamentarium for malaria prevention.
An internal control for the detection of Onchocerca volvulus DNA by PCR–ELISA and rapid detection of specific PCR products by DNA Detection Test StripsTM
Authors: Pischke S. , Büttner D. W. , Liebau E. , Fischer P.
Published: March 2003

We developed a polymerase chain reaction–enzyme‐linked immunosorbent assay (PCR–ELISA) for the detection of Onchocerca volvulus DNA. To standardize the PCR and to avoid false‐negative results, an internal control DNA was co‐amplified by the same set of primers. We differentiated the wild‐type PCR product of the O‐150 DNA sequence from the internal control by specific DNA probes. Detection of biotinylated PCR products by DNA probes was performed by ELISA to quantify the PCR product or by DNA Detection Test StripsTM as a rapid field technique. The methods were evaluated on skin biopsies from individuals living in an area endemic for O. volvulus in Uganda, but with low microfilaria densities because of ivermectin treatment. Microfilaria density was assessed by a single skin snip and a second skin snip was examined by PCR. Among 69 samples from microfilaria carriers, 47 (68%) were positive by ELISA and 55 (80%) by test strip detection of PCR products. When 39 samples of microfilaria‐negative individuals from the same area were tested, 10 (27%) were positive by ELISA and 12 (31%) by test strips. None of the 19 samples obtained from persons living in an area not endemic for O. volvulus but endemic for Mansonella streptocerca was positive in either test. Although the ELISA is theoretically more sensitive than the test strips for the detection of PCR products, examination of field samples revealed that the test strip method had a higher operational sensitivity and was more convenient to perform. Thus, the DNA Detection Test StripsTM are a rapid and low‐tech tool for identification of PCR products in laboratories of countries endemic for onchocerciasis.
Sulphadoxine/pyrimethamine: an appropriate first‐line alternative for the treatment of uncomplicated falciparum malaria in Ghanaian children under 5 years of age
Authors: Driessen G. J. A. , Van Kerkhoven S. , Schouwenberg B. J. J. W. , Bonsu G. , Verhave J. P.
Published: March 2003

OBJECTIVE  To assess whether chloroquine (CQ) still is an appropriate first‐line drug for the treatment of uncomplicated falciparum malaria in Ghana and whether sulphadoxine/pyrimethamine (SP) could be a good alternative.

METHOD  The parasitological, clinical and haematological responses to CQ and SP were studied in children < 5 years of age according to a modified WHO 28‐day in vivo protocol. A total of 142 children attending the outpatients department meeting the inclusion criteria were randomly assigned to the CQ (n=72) or SP (n=70) group.

RESULTS  In the CQ group, 15 children (20.8%) exhibited early clinical failure (within 3 days) compared with only 1 (1.4%) in the SP group (P < 0.01). The clinical failure rate before day 14 (early treatment failure plus late treatment failure before day 14) also showed a marked advantage in favour of the SP group (1.4 against 29.2%). The median time to clinical failure was 11.5 days in the CQ group and 26 days in the SP group (P < 0.01). Of the 72 children treated with CQ, 9 (12.5%) had RIII resistance and 19 (26.4%) had RII resistance. A total of 36 (50.0%) were sensitive to CQ. From the 70 children treated with SP, none had RIII or RII resistance. There was no difference in haematological response between the two treatment groups.

CONCLUSION  Although there is little concordance on when to change treatment policy, the high resistance to CQ in this study supports the change to another first‐line drug for children under 5 years of age. SP seems to be a good alternative, although a high RII and RIII resistance against this drug has already been reported in the coastal zones of Ghana.
Alanine metabolism in acute falciparum malaria
Authors: Pukrittayakamee S. , Krishna S. , Ter Kuile F. , Wilaiwan O. , Williamson D. H. , White N. J.
Published: March 2003

We investigated the integrity of the gluconeogenic pathway in severe malaria using alanine metabolism as a measure. Alanine disposition and liver blood flow, assessed by indocyanine green (ICG) clearance, were measured simultaneously in 10 patients with falciparum malaria (six severe and four moderately severe malaria). After intravenous infusion of alanine (0.3 g/kg), glucose increments (AUC0−55 min) were lower in patients with severe malaria than in those with moderately severe malaria (median = 508 vs. 808 mmol/min/l; P = 0.055). There were no significant differences in the other metabolite increments (alanine, lactate and pyruvate; P ≥ 0.27). The two fatal cases had markedly delayed alanine removal (larger AUC0−55 min), prolonged T½ and slower clearance (P ≤ 0.007). Overall the increments in blood alanine correlated directly with lactate increments (rs = 0.84; P = 0.002) and inversely with glucose (rs = −0.70; P = 0.025). Between acute and convalescent studies, the increments (AUC0−55 min) of alanine and glucose were not significantly different (P ≥ 0.07) but the increments of lactate and pyruvate were lower in convalescence. Thus, the ratio of the increments of alanine to those of lactate and pyruvate were significantly higher in the convalescent study (P ≤ 0.017). The mean (SD) ICG clearance during acute malaria was not significantly different to that in convalescence (21.6 ± 9.3 vs. 34.1 ± 15.5 ml/min/kg; P = 0.25). During the acute study, there was a significant inverse correlation between ICG clearance and the post‐infusion increments of lactate (rs = −0.63, P = 0.049) and pyruvate (rs = −0.74, P = 0.014). These data indicate that alanine clearance is impaired in acute falciparum malaria in proportion to the severity of illness and suggest an important role for anaerobic glycolysis in the pathogenesis of hypoglycaemia in severe malaria.
Plasmodium falciparum multiple infections in Mozambique, its relation to other malariological indices and to prospective risk of malaria morbidity
Authors: Mayor Alfredo , Saute Francisco , Aponte John J. , Almeda Jesús , Gómez‐Olivé F. Xavier , Dgedge Martinho , Alonso Pedro L.
Published: March 2003

We describe the frequency of Plasmodium falciparum clones infecting individuals living in a rural area of southern Mozambique and analyse the relationship between multiplicity of infection, age and other malariometric indices, including prospective risk of clinical malaria. The genotyping was based on the use of restriction fragment length polymorphism–polymerase chain reaction (RFLP–PCR) analysis of P. falciparum merozoite surface protein 2 (msp2). We analysed 826 samples collected during five cross‐sectional surveys from residents of Manhiça ranging in age from 4 months to 83 years. We also determined the multiplicity of infection in samples obtained from 6‐month‐old infants (n = 79) and children <10 years (n = 158) who were then treated and followed prospectively for 1 year or 75 weeks, respectively. Multiplicity of infection did not vary significantly during the first year of life, but increased thereafter, and decreased during adulthood to the levels found in infants. With increasing multiplicity of infection, there was a statistically significant decrease in the risk of submicroscopic infections. There was also a significant correlation between multiplicity of infection and parasite density in infants, children <4 years of age and adults, suggesting that high densities increase the probability of discriminating more clones in complex infections. We found that the relationship between multiple infections and malaria morbidity is age‐dependent. In infants, the risk of subsequent episodes of clinical malaria was related to the parasite density but not to baseline multiplicity of infection. In older children, however, the more clones a child carried, the more likely they were to have a clinical malaria episode, and this was true after adjusting for parasite densities. This change in the association between multiplicity and risk of clinical malaria may indicate a shift in the host response to P. falciparum.
Feline Langerhans cells migrate from skin and vaginal mucosa to regional lymph nodes during experimental contact sensitization with fluorescein isothiocyanate
Authors: Marchal Isabelle Saint‐AndrÉ , Martin Jean‐Pierre , Kirn AndrÉ , Magnol Jean‐Pierre , Dezutter‐Dambuyant Colette , Schmitt Daniel , Marchal Thierry
Published: March 2003

Recently, feline Langerhans cells (LC) were immunophenotypically characterized as CD1a+, CD4+, CD18+, CD53+ and MHC II+ cells. In mice, these cells are known to internalize antigens and to migrate to the lymph nodes (LN). In the cat, we have investigated the migration of LC from the skin and vaginal mucosa to regional LN in response to chemical exposure (fluorescein isothiocyanate). Three days after the administration of a FITC solution on the posterior limb of two male cats and in the vagina of one female, a biopsy was carried out on the draining LN of the sensitized zones. Immunostaining with monoclonal antibodies anti‐CD79, anti‐CD8, and antibodies recognizing LC was performed on cytospins and frozen sections of LN and showed that a majority of FITC+ cells displayed a LC immunophenotype and were localized in T‐cell areas, but not in follicular areas. These results are the first evidence of migration of feline LC from skin and vaginal mucosa to the regional LN.
Clinical and histological evaluation of immediate and delayed flea antigen intradermal skin test and flea bite sites in normal and flea‐allergic cats
Authors: Lewis  , Ginn  , Kunkle
Published: March 2003

Seven cats diagnosed as flea allergic by specific criteria and seven normal control cats were exposed to flea bites in a controlled manner and were given intradermal injections of 1:1000 w/v flea antigen. Subjective evaluation of gross lesions and documentation of histological changes at flea antigen intradermal skin test (IDST) and flea bite sites were performed at 15 min, 24 h and 48 h after IDST or flea exposure. Control cats did not develop an immediate gross reaction to either flea bites or the intradermal injection of flea antigen. All seven flea‐allergic cats had an immediate gross reaction at the site of IDST with flea antigen; five of these cats also developed immediate gross reactions to flea bites. Three of seven flea‐allergic cats developed a gross 24 h and/or 48 h delayed reaction at the flea antigen IDST sites. These three and one other cat had both an immediate and delayed gross reaction to flea bites. Histological examination of 15 min skin specimens from IDST and flea bite sites of flea‐allergic cats were similar with a mild lymphocytic, histiocytic and mastocytic superficial perivascular dermatitis. Histological examination of 24 h and 48 h skin specimens from IDST and flea bite sites of flea‐allergic cats showed that they were often indistinguishable. Histological features of IDST and flea bite sites of flea‐allergic cats at 24 h consisted of a perivascular to diffuse predominately eosinophilic dermatitis and mural folliculitis with variable epidermal necrosis and ulceration.
Sebaceous adenitis in four domestic rabbits (Oryctatagus cuniculus)
Authors: White Stephen D. , Linder Keith E. , Schultheiss Patricia , Scott Kathryn V. , Garnett Page , Taylor  , Best  , Walder Emily J. , Rosenkrantz Wayne , Yaeger Julie A.
Published: March 2003

Four domestic rabbits were presented with a history of nonpruritic scale. Multiple skin biopsies revealed findings compatible with sebaceous adenitis as reported in other species: inflammation directed at the sebaceous gland, and/or an absence of sebaceous glands, a perifollicular lymphocytic infiltrate at the level of the absent sebaceous glands, hyperkeratosis, follicular keratosis, follicular dystrophy, perifollicular fibrosis, and a mural infiltrative lymphocytic folliculitis. Histological changes not consistent with sebaceous adenitis in other species were interface dermatitis and interface folliculitis with single cell necrosis and basal cell hydropic degeneration.
Comparison of T‐lymphocyte proliferation in canine epitheliotropic lymphosarcoma and benign lymphocytic dermatoses
Authors: Murphy Marcia K. , Olivry Thierry
Published: March 2003

The lesions of patch/plaque cutaneous T‐cell lymphosarcoma (CTCL) are similar to many benign inflammatory dermatoses, both histopathologically and clinically. In humans, attempts to develop a simple, reliable immunophenotypic technique to differentiate between the malignant and benign dermatoses have been unsuccessful. The purpose of our study was to determine, using a proliferating cell nuclear antigen (PCNA)/CD3 double immunolabelling technique of paraffin‐embedded sections, if the rate of T‐cell proliferation in canine CTCL was greater than that of other diseases with non‐neoplastic lymphocyte epitheliotropism. We selected cases of patch/plaque (PP) and tumour stage CTCL, erythema multiforme (EM) and cutaneous lupus erythematosus (CLE). We did not find a significant difference in the rate of T‐cell proliferation in the epithelia nor the superficial dermis between PP‐CTCL and EM. Whereas epithelial T‐cell proliferation is significantly higher in PP‐CTCL than CLE, it is not diagnostically useful because of overlap in the labelling indices.
The association of Staphylococcus schleiferi with canine pyoderma
Authors: Frank L. A. , Williamson N. L. , Wilkes R. P. , Kania S. A. , Hnilica K. A. , Bemis D. A.
Published: March 2003

Staphylococcus schleiferi is a recently recognized organism with potential pathogenic implications in human and veterinary medicine. The purpose of this study was to determine the frequency of S. schleiferi in canine pyodermas and see if methicillin resistance (MR) is associated with this organism. Cultures were obtained from dogs with pyoderma over a 1‐year period. It was determined if the pyoderma was a first‐time or recurrent one, and if the dog was receiving antibiotics at the time of culture. Of 15 dogs with first‐time pyoderma, four dogs were receiving antibiotics at the time of culture: S. schleiferi was not cultured from any dog in this group. Cultures were obtained from 27 dogs with recurrent infection that were not receiving antibiotics: S. schleiferi was cultured from five of these dogs; three of the five S. schleiferi‐cultured isolates were MR. Cultures were obtained from 12 dogs with recurrent pyoderma while receiving antibiotics: S. schleiferi was cultured from nine of these dogs; eight of the nine S. schleiferi‐cultured isolates were MR. Five of the 12 dogs had been cultured previously while not receiving antibiotics. Three of these dogs cultured positive for S. intermedius initially, and then ‐cultured; one dog cultured S. schleiferi positive both times; and one dog cultured S. schleiferi positive, then S. intermedius positive. To the authors’ knowledge, this is the first report of S. schleiferi associated with canine pyoderma. Results indicate that S. schleiferi is cultured more often from dogs with recurrent pyodermas while receiving antibiotics. MR is frequently associated with S. schleiferi.

 Funded by the Department of Small Animal Clinical Sciences and a grant from the Center of Excellence.
Interactions between weeds of winter wheat under different fertilizer, cultivation and weed management treatments
Authors: McCLOSKEY  , FIRBANK  , WATKINSON  , WEBB
Published: March 2003

Interactions between the weeds Bromussterilis L., Galium aparine L. and Papaver rhoeas L. were investigated over 3 years of continuous winter wheat (Triticum aestivum L.) across a factorial combination of organic and conventional fertilizer, and ploughing and hand‐roguing contrasted with minimum tillage and herbicide. The species were sown separately and together at 50 seeds m−2 per species at the start of the experiment in October 1989. In addition, there were weed‐free and background‐weed controls. Weed densities were monitored at roughly monthly intervals and crop yield recorded for three seasons. B. sterilis populations increased 10‐fold under minimum tillage, but declined under ploughing. Densities of P. rhoeas remained largely low. G. aparine increased on the organically fertilized minimum‐tillage plots, except where B. sterilis was present; the high densities of B. sterilis reduced the population size of G. aparine. Crop yield was influenced most strongly by the fertilizer treatment in the first season, but later the density of B. sterilis was by far the most important factor; the evidence of interactive effects of the different weed species on crop yield was weak at best. Interactive effects of arable weed species can be observed, but only at very high densities, and so are unlikely to be of widespread economic importance.
Phytochrome‐mediated germination control of Datura stramonium L. seeds after seed burial
Authors: BENVENUTI  , MACCHIA
Published: March 2003

A series of experiments investigated the light sensitivity of buried weed seeds both within and outside the soil gas microenvironment. Light sensitivity of Datura stramonium L. seeds was found to be increased markedly by a period of soil burial; seeds showed a pronounced germination response even in far‐red light (724 nm). Despite this elevated light sensitivity (even to less than 0.01% of incident light), soil overlying buried seeds was sufficient to neutralize the germination trigger. Furthermore, in situ irradiation of buried seeds was found to be virtually ineffective as a germination trigger, showing that the gaseous environment surrounding buried seeds may represent the main obstacle to germination. It is suggested in this study that the soil environment restricts the removal of the germination‐inhibiting products of fermentation metabolism. This suggestion is supported by the finding that gas exchange within the seed:soil complex, achieved by flushing with nitrogen, partially restores seed light sensitivity. In addition, it was found that with increasing sowing depth, the germination response was attenuated and also became less dependent on seed phytochrome photoequilibrium conditions. This demonstrates that the phenomenon of germination photoinduction can be reversed by other environmental factors that reduce or eliminate phytochrome physiological activity. Finally, it was shown that seed very low fluence response (VLFR) is triggered only when gas exchange around buried seeds co‐occurs with light exposure.
Competition between safflower and weeds as influenced by crop genotype and sowing time
Authors: PAOLINI  , PUGLIA S. DEL , PRINCIPI  , BARCELLONA  , RICCARDI
Published: March 2003

The effects of crop genotype and sowing time on competition between safflower (Carthamus tinctorius L.) and weeds were investigated in a 2‐year field study. Each year, safflower was grown as a pure stand and in mixture with a natural weed infestation, mostly represented by Polygonum aviculare L., Fallopia convolvulus (L.) A. Löve and Chenopodium album L., in an additive design including weed stands grown without the crop. Grain yield reduction ranged from about 50% to 80% depending on crop genotype, and was higher under spring sowing (mid‐March) than under winter sowing (mid‐February). In general, those genotypes incurring the least yield reduction gave the greatest suppression of weed biomass. More competitive genotypes also tended to reduce the proportion of C. album in the weed biomass at harvest, particularly in 1994 (the wetter growing season). The competitive ability of the crop was mainly correlated with its biomass at early growth stages, but was not related to its grain‐yielding ability in the absence of weeds. Results showed that more competitive crops may be obtained by sowing the most competitive genotypes early. Selecting for higher competitive ability in safflower does not seem to imply a reduction in grain‐yielding ability.
Modelling the effect of crop and weed on herbicide efficacy in wheat
Authors: BRAIN  , WILSON  , WRIGHT  , SEAVERS  , CASELEY
Published: March 2003

Recommended field application rates of herbicides have to give effective weed control in every situation and are, thus, often higher than that required for specific fields. An understanding of the interaction between crop:weed competition and herbicide dose may, in many cases, allow herbicide application rates to be reduced, important both environmentally and economically. We have developed a model of the interaction between crop:weed competition and herbicide dose, using an empirical model of the relationship between crop yield and weed biomass (related to weed density), and an empirical model of the relationship between weed biomass and herbicide dose. The combined model predicts crop yield, given herbicide dose and weed biomass at an interim assessment date. These crop yield loss predictions may be used to quantify the herbicide dose required to restrict yield loss to a given percentage. Parameters of the model were estimated and the model tested, using results from experiments, which used cultivated oats (Avena sativa) or oilseed rape (Brassica napus) as model weeds in a crop of winter wheat (Triticum aestivum).For the crop:weed:herbicide combinations investigated there was little increase in crop yield for herbicide dose rates above 20% of recommended field rates, in broad agreement with the model predictions. There may still be potential for further reduction below this level on economic grounds; the model could be used to estimate the `break‐even' herbicide dose.
Soil potassium supply and Rumex obtusifolius and Rumex crispus abundance in silage and grazed grassland swards
Authors: HUMPHREYS  , JANSEN  , CULLETON  , MACNAEIDHE  , STOREY
Published: March 2003

Three experiments investigating factors influencing the abundance of Rumex spp. (docks) in silage and grazed grassland swards are presented. In Experiment 1, Rumex obtusifolius plants were sown with perennial ryegrass and white clover in pots in March and harvested at either 5‐ or 10‐week intervals between June and October. The 10‐week harvest interval increased root dry‐matter production of R. obtusifolius compared with the 5‐week interval; herbage (above‐ground material) production was not significantly affected. In Experiment 2, R. obtusifolius and Rumex crispus population densities in grassland swards were correlated with soil P, K and Mg concentrations, and soil pH. In general, silage swards contained higher population densities than grazed swards. There were significant positive correlations between soil K concentrations and abundance of Rumex spp. in grazed swards and in silage swards. In Experiment 3, R. obtusifolius was sown with perennial ryegrass in pots in March. Treatments consisted of nine rates of K fertilization ranging between the equivalent of 0 and 600 kg K ha−1 year−1. Herbage was harvested at regular intervals (4–6 weeks except during the winter) until May of the following year. In general, perennial ryegrass dry‐matter yields were not greatly affected by soil K, whereas limited soil K supply tended to reduce dry‐matter production of R. obtusifolius. It is possible that maintenance of moderate soil K concentrations may play a role in limiting abundance of Rumex spp. in grassland.
Seasonal changes in the germination of buried seeds of Monochoria vaginalis
Authors: CHEN  , KUO
Published: March 2003

This study investigates the seasonal variation of germination ability of buried seeds of Monochoria vaginalis (Burm.f.) Presl var. plantaginea Solms. The field‐collected seeds were buried in a flooded or an upland field and then exhumed monthly. The exhumed seeds were germinated under four temperature regimes. The seeds exhumed from the flooded soil were dormant at the beginning of burial and proceeded into a conditional dormancy/non‐dormancy/conditional dormancy cycle throughout the remaining period of the experiment. The seeds exhumed monthly from the non‐flooded soil exhibited an annual dormant cycle, which is dormancy/conditional dormancy/non‐dormancy/conditional dormancy/dormancy. At day and night temperatures of 25/20 °C, the exhumed seeds from both the flooded and the upland soil resembled each other in terms of seasonal variation of the germination percentage. In September and October, more seeds exhumed from upland soil failed to germinate under higher temperature than from flooded soil. Strictly avoiding exposure to light during seed exhuming and seed testing prevented the seeds from germinating. A short exposure of the exhumed seeds to light during preparation promoted dark germination when the seeds were at the non‐dormant stage. The potential implications of our results for weed management strategies in rice production are discussed.
New insights concerning the ecology and the biology of Rhamphicarpa fistulosa (Scrophulariaceae)
Authors: OUÉDRAOGO  , NEUMANN  , RAYNAL‐ROQUES  , SALLÉ  , TUQUET  , DEMBÉLÉ
Published: March 2003

Rhamphicarpa fistulosa (Hochst.) Benth. is a parasitic member of the Scrophulariaceae occurring sporadically on rice and other cereal crops in tropical Africa. Relatively little is known about this parasite, and some aspects concerning its life cycle and its impact on crops are reported in the present paper. The size, the shape and the seedcoat ornamentation of R. fistulosa are described and compared with those of Striga spp. The seeds do not require a host root exudate to stimulate germination but do require light. As in the case of Striga spp., they show a period of dormancy of at least 6 months. When the parasite roots come into close contact with a host root, they swell and develop haustoria, which form a direct xylem connection between host and parasite. In vitro and pot culture experiments establish that R. fistulosa is a facultative parasite, as it is able to complete its life cycle without a host plant. However, plants growing under these conditions are much smaller and produce only a few seeds. Field observations indicate that in some places, R. fistulosa can destroy cereals. The agronomic hazard represented by this member of the Scrophulariaceae is discussed.
Interannual variation in weed biomass on arable land in Sweden
Authors: Milberg  , Hallgren  , Palmer
Published: March 2003

Data were analysed on weed biomass from untreated plots in 2672 field experiments conducted in spring‐ and autumn‐sown cereal and oilseed crops in Sweden 1972–1992. The coefficient of variation (CV) among years in the biomass of annual weeds per square metre was 29% in autumn‐sown crops. In spring‐sown crops, which had less weed biomass, the corresponding value was 49%. The biomass of summer annuals varied most (105%). Low winter temperatures seemed to increase the biomass of weeds in autumn‐sown crops. In spring‐sown crops, weed biomass production was higher in years with high rainfall during late spring. Partial ordination (pCCA) of weed data indicated that the interannual variations in autumn‐sown crops were mainly manifested by the occurrence of summer annuals. Results from similar ordination of data from spring‐sown crops were partly explained by the occurrence of winter annuals.
Cutting weeds with a CO2 laser
Authors: Heisel T , Schou J , Christensen S , Andreasen C
Published: March 2003

Stems of Chenopodium album. and Sinapis arvensis. and leaves of Lolium perenne. were cut with a CO2 laser or with a pair of scissors. Treatments were carried out on greenhouse‐grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non‐linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO2 laser than C. album. When stems were cut below the meristems, 0.9 and 2.3 J mm−1 of CO2 laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2‐true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne.
Diclofop‐methyl resistance in populations of Lolium spp. from central Italy
Authors: Bravin F , Zanin G , Preston C
Published: March 2003

Populations of Lolium spp. collected in central Italy were screened for resistance to acetyl‐coenzyme A carboxylase (ACCase)‐inhibiting herbicides and compared with known susceptible and resistant Lolium rigidum (Gaud.) populations from Australia. Populations Roma’94 and Tuscania’97 were up to 8‐ and 7.5‐fold more resistant to diclofop‐methyl, respectively, than susceptible populations in pot experiments. However, populations Tarquinia’97 and Vetralla’94 were not resistant. Diclofop‐methyl resistance levels in the Italian populations were lower than in the Australian populations SLR31 and WLR96 (16.5 and > 64 times more resistant than S respectively). In an agar germination test, Tuscania’97 showed low levels of cross‐resistance to fluazifop‐p‐butyl, whereas no cross‐resistance was found in the Roma’94 population.
Weed flora and soil seedbanks in fields dominated by Imperata cylindrica in the moist savannah of West Africa
Authors: Chikoye D , Ekeleme F
Published: March 2003

Imperata cylindrica (L.) Raeuschel is a dominant and infamous grass weed in the savannah of West Africa. Research to reduce the weed to non‐damaging levels is a priority activity at many agricultural institutions. The successful development and implementation of long‐term I. cylindrica management strategies depend on the ability to predict changes in weed composition after I. cylindrica has been controlled effectively. The weed flora and soil seedbank were assessed from 329 fields dominated by this species in the fringes of the humid forest (HFF), coastal/derived savannah (CDS) and in the southern Guinea savannah (SGS) in 1996 and 1997. The objectives of the study were to correlate species composition of the weed flora with that of the soil seedbank and to determine the effect of management factors and soil properties on the composition of the weed flora. Species richness in the weed flora and in the weed seedbank was higher in the SGS than in the CDS and HFF. Mean weed density per field was generally higher in the HFF (156 ± 25.0 weeds m–2) than in the CDS (108 ± 8.1 weeds m–2) and in the SGS (92 ± 6.3 weeds m–2). Weed composition varied with agroecological zone as well as with management factors and soil properties. Sørenson’s index of similarity was low (mean=0.20) in all zones, indicating poor similarity between the weed flora above‐ground and the soil seedbank.
Successful prenatal exclusion of an unspecified subtype of severe epidermolysis bullosa
Authors: Shimizu MD Hiroshi , Horiguchi MD Yuji , Suzumor MD Kaoru , Watanabe MD Isao , Owaribe PhD Katsushi , Nishikawa MD Takeji
Published: March 2003

Background In most cases of prenatal diagnosis of epidermolysis bullosa (EB), the subtype of severe EB from which the fetus is at risk is identified by studying the specimens of the proband. In this study, the parents of a child with an unspecified subtype of severe EB sought prenatal diagnosis for their second and third pregnancies.

Methods The firstborn of a couple (the proband) suffered generalized blistering and erosions of the skin present from delivery, and died on the 11th postnatal day of severe EB of an unspecified type. The only diagnostic specimen available from the first infant was a conventionally stained skin section for light microscopy that showed the dermo–epidermal separation. For prenatal diagnosis in the second and third pregnancies, fetal skin biopsies were performed at 19 weeks of gestation.

Results In both cases, fetal skin showed no ultrastructural abnormalities and no evidence of dermo–epidermal separation. Indirect immunofluorescence was positive for monoclonal antibodies against type VII collagen, laminin 5, uncein, α6 and β4 integrins, BPAG2, and HD1/plectin, which are known to be reduced or absent in specific subsets of severe EB. The pregnancies were therefore continued, and normal healthy second and third children were delivered.

Conclusions Fetal skin biopsy, together with a panel of newly developed monoclonal antibodies, provided reliable prenatal diagnosis in the present family in which preliminary information of the EB proband was limited.
Different patterns of in vitro acantholysis in normal human skin samples explanted from different sites of the body
Authors: Ruocco Vincenzo , Brenner Sarah , Ruocco Eleonora , De Angelis Francesca , Lombardi Maria Luisa
Published: March 2003

Background The factors that contribute to a preferential anatomic localization of pemphigus lesions are not well known. In particular, the question arises as to whether certain skin areas may be more acantholysis‐prone than others.

ObjectiveTo verify whether, in pemphigus patients, a different susceptibility to acantholysis exists among different cutaneous regions, the technique of tissue cultures was used.

MethodsNormal human skin explants from two distinct anatomic regions (back and buttocks) of two former pemphigus patients were cultured in vitro in the presence of enalapril (6 mM) or cystamine (10 mM), two substances with a proven biochemical acantholytic effect. After 4 days of culture, the tissues were processed for standard histology.

ResultsDiffuse acantholysis, with large intraepidermal splits, was observed in the explants taken from the backs of both subjects and cultured with either enalapril or cystamine. Mild to moderate acantholytic changes were detected in the explants taken from the buttocks of both subjects and cultured with either enalapril or cystamine. No structural changes were seen in the control cultures.

ConclusionsPemphigus patients present different thresholds of acantholysis in different areas of their bodies. This might explain, at least in part, certain preferential anatomic localizations of pemphigus lesions.