bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of the movement and host range properties of a plant virus vector through DNA shuffling
Authors: Toth Rachel L. , Pogue Gregory P. , Chapman Sean 
Published: March 2003

SummaryVirus expression vectors based on the tobacco mosaic virus (TMV) genome are powerful tools for foreign gene expression in plants. However, the inclusion of increased genetic load in the form of foreign genes limits the speed of systemic plant invasion and host range of these vectors due to reduced replication and movement efficiencies. To improve these properties of TMV vectors, the gene encoding the 30‐kDa movement protein was subjected to mutagenesis and DNA shuffling. A vector that expresses the green fluorescent protein was used to allow simple visual discrimination of mutants with enhanced movement phenotypes. An initial round of mutagenesis produced 53 clones with a faster local movement phenotype. Two subsequent rounds of DNA shuffling produced additional clones that showed further increased rates of cell‐to‐cell movement and degrees of systemic invasion in restrictive hosts. Surprisingly, sequence analysis of the best performing shuffled genes revealed alterations resulting in coding and silent changes in the movement protein gene. Separation of these coding and silent alterations into distinct gene backgrounds revealed that each contributes to improved movement protein function to differing degrees. The resulting vectors demonstrate that the complex activities of the movement protein genes of viruses can be evolved to have improved movement phenotypes, as evidenced by cell‐to‐cell and systemic invasion. The experiments produced improved vectors that will be of use both for in planta functional screening and for therapeutic protein production and demonstrated the power of shuffling for plant virus vector improvement.
Conformational features of crystal‐surface cellulose from higher plants
Authors: Viëtor Remco J. , Newman Roger H. , Ha Marie‐Ann , Apperley David C. , Jarvis Michael C. 
Published: March 2003

SummaryNative cellulose in higher plants forms crystalline fibrils a few nm across, with a substantial fraction of their glucan chains at the surface. The accepted crystal structures feature a flat‐ribbon 21 helical chain conformation with every glucose residue locked to the next by hydrogen bonds from O‐3′ to O‐5 and from O‐2 to O‐6′. Using solid‐state NMR spectroscopy we show that the surface chains have a different C‐6 conformation so that O‐6 is not in the correct position for the hydrogen bond from O‐2. We also present evidence consistent with a model in which alternate glucosyl residues are transiently or permanently twisted away from the flat‐ribbon conformation of the chain, weakening the O‐3′ − 0‐5 hydrogen bond. Previous molecular modelling and the modelling studies reported here indicate that this ‘translational’ chain conformation is energetically feasible and does not preclude binding of the surface chains to the interior chains, because the surface chains share the axial repeat distance of the 21 helix. Reduced intramolecular hydrogen bonding allows the surface chains to form more hydrogen bonds to external molecules in textiles, wood, paper and the living plant.
Transgene integration in aspen: structures of integration sites and mechanism of T‐DNA integration
Authors: Kumar Sandeep , Fladung Matthias 
Published: March 2003

SummaryTo obtain insight into the mechanism of transferred DNA (T‐DNA) integration in a long‐lived tree system, we analysed 30 transgenic aspen lines. In total, 27 right T‐DNA/plant junctions, 20 left T‐DNA/plant junctions, and 10 target insertions from control plants were obtained. At the right end, the T‐DNA was conserved up to the cleavage site in 18 transgenic lines (67%), and the right border repeat was deleted in nine junctions. Nucleotides from the left border repeat were present in 19 transgenic lines out of 20 cases analysed. However, only four (20%) of the left border ends were conserved to the processing end, indicating that the T‐DNA left and right ends are treated mechanistically differently during the T‐DNA integration process. Comparison of the genomic target sites prior to integration to the T‐DNA revealed that the T‐DNA inserted into the plant genome without any notable deletion of genomic sequence in three out of 10 transgenic lines analysed. However, deletions of DNA ranging in length from a few nucleotides to more than 500 bp were observed in other transgenic lines. Filler DNAs of up to 235 bp were observed on left and/or right junctions of six transgenic lines, which in most cases originated from the nearby host genomic sequence or from the T‐DNA. Short sequence similarities between recombining strands near break points, in particular for the left T‐DNA end, were observed in most of the lines analysed. These results confirm the well‐accepted T‐DNA integration model based on single‐stranded annealing followed by ligation of the right border which is preserved by the VirD2 protein. However, a second category of T‐DNA integration was also identified in nine transgenic lines, in which the right border of the T‐DNA was partly truncated. Such integration events are described via a model for the repair of genomic double‐strand breaks in somatic plant cells based on synthesis‐dependent strand‐annealing. This report in a long‐lived tree system provides major insight into the mechanism of transgene integration.
Fluorescence microscopy: a powerful technique to detect low GUS activity in vascular tissues
Authors: Rech Philippe , Grima‐Pettenati Jacqueline , Jauneau Alain 
Published: March 2003

AbstractWe have previously shown that the Eucalyptus gunnii EgCAD2 promoter was preferentially expressed in vascular tissues in different transgenic plants (poplar, tobacco, Arabidopsis and grapevine). In order to delineate the cis elements governing this vascular expression pattern, promoter deletion analysis was performed allowing us to identify the proximal region [−340/−124] as essential for vascular cambium/xylem‐specific expression. In plants transformed with the smallest promoter region [−124/+117], the GUS activity was difficult to detect using conventional bright field microscopy. To overcome this problem, we used fluorescence microscopy, enabling us to show that the [−124/+117] region contained cis‐elements driving activity in phloem fibres but not in secondary xylem. The technical improvement of the histochemical detection of GUS activity using fluorescence microscopy enables accurate investigation of low GUS activity in phenol‐rich tissues.
Heterogeneity of the blood group Ax allele: genetic recombination of common alleles can result in the Ax phenotype
Authors: Olsson  , Chester  
Published: March 2003

The Ax phenotype is an important subgroup of the ABO blood group system. Its inheritance does not always follow Mendelian rules and recent studies suggested that different alleles can result in this phenotype. This suggestion has been explored by cloning and sequencing exons 6 and 7 of the ABO gene and the intervening intron from members of six unrelated families expressing the Ax phenotype.Two families showed the previously described T646A ‘Ax’ mutation as the only deviation from the consensus A1 allele. In two other families the Ax phenotype was inherited as two different recombinational gene products. Combination of exon 6 derived from A or B/O2 alleles with exon 7 from the O1v allele created two novel alleles that have four O1v‐characteristic nucleotide substitutions in exon 7, including T646A. Sequencing and analysis of polymorphisms in intron 6 defined the crossing‐over zones of these hybrid alleles. Southern blot confirmed the hybrid formation by detecting ABO‐related polymorphisms ≈ 1.35 kb downstream from the ABO reading frame.The remaining two families expressed the Ax phenotype via an allele having A2‐specific mutations. Thus, a heterogeneous molecular background leads to the serologically defined Ax phenotype and may well explain the different modes of inheritance observed.
How useful are anthropometric, clinical and dietary measurements of nutritional status as predictors of morbidity of young children in central Africa?
Authors: Tonglet René 
Published: March 2003

Summary

objective  To identify useful predictors of morbidity of young children in central Africa. method  Population‐based follow‐up study in Northern Kivu, Congo, of 842 children under two years of age who completed weekly follow‐up interviews and health examinations during three months. Main outcome measures were crude and adjusted effects of summary measures of nutritional status on one‐month cumulative incidence of malaria, respiratory illness, and diarrhoea. results  Anthropometric indicators appeared to perform badly in predicting morbidity. In contrast, nonanthropometric variables such as growth as judged by the caretaker, child's diet at the time of examination, and occurrence of disease in the month preceding the interval of observation were useful. conclusions  In the context of the ‘Sick Child Initiative’, simple tests and diagnostic tools to improve quality of both prevention and cure in first‐level facilities need to be identified. Focusing on non‐anthropometric indicators should be encouraged to offer a comprehensive appraisal of health status to all children.
The burden of mucocutaneous conditions and the association with HIV‐1 infection in a rural community in Uganda
Authors: Mayanja Billy , Morgan Dilys , Ross Amanda , Whitworth James 
Published: March 2003

Summary objective To determine the prevalence of mucocutaneous conditions and their association with HIV‐1 infection in a rural community in Uganda. methods In a prospective cohort study, participants were recruited from a large population study and invited to attend a clinic every 3 months for a detailed medical interview and a thorough physical examination. All findings including mucocutaneous findings were coded onto a standard questionnaire. results By the end of 1996, 436 participants had provided 1450 person years of observation (pyo); 646 pyo in HIV‐positives and 804 pyo in HIV‐negatives. Overall, 70% of participants had a skin condition during follow‐up, and although skin conditions were significantly more common in HIV‐positive subjects, the background level in HIV‐negative subjects was high (77.3% and 63.6%, respectively). Herpes zoster, thin/sparse hair, maculo‐papular rash and prurigo were significantly more common in the HIV‐positives. Kaposi sarcoma, palmar/plantar rash and herpes zoster had positive predictive values for HIV infection of over 80%. Oral conditions were found in over 40% of participants and were significantly more common in HIV‐positive subjects. Oral candidiasis and Kaposi sarcoma were significantly more frequent among HIV‐positives. conclusion HIV infection increases the already high burden of mucocutaneous diseases in this rural population. We identified some conditions that are more common in HIV and others that can be used as indicators of HIV infection.
Antibiotic dispensing by drug retailers in Kathmandu, Nepal
Authors: Wachter David A. , Joshi Mohan P. , Rimal Binaya 
Published: March 2003

Summary objectives  To assess over‐the‐counter antimicrobial dispensing by drug retailers in Kathmandu, Nepal, for rationality, safety, and compliance with existing government regulations. methods  Standardized cases of dysuria in a young adult male and acute watery diarrhoea in a child were presented by a mock patient to retailers at 100 randomly selected pharmacies. Questions asked by retailers and advice and medications given at their initiative were recorded. results  All retailers engaged in diagnostic and therapeutic behaviour beyond their scope of training or legal mandate. Historical information obtained by retailers was inadequate to determine the nature or severity of disease or appropriateness of antimicrobial therapy. 97% (95% CI = 91.5–99.4%) of retailers dispensed unnecessary antimicrobials in diarrhoea, while only 44% (95% CI = 34.1–54.3%) recommended oral rehydration therapy and only 3% (95% CI = 0.6–8.5%) suggested evaluation by a physician. 38% (95% CI = 28.5–48.2%) gave antimicrobials in dysuria, yet only 4% (95% CI = 1.1–9.9%) adequately covered cystitis. None covered upper urinary tract or sexually transmitted infections, conditions which could not be ruled out based on the interviews, and only 7% (95% CI = 2.9–13.9%) referred for a medical history and physical examination necessary to guide therapy. conclusions  Although legislation in Nepal mandates a medical prescription for purchase of antibiotics, unauthorized dispensing is clearly problematic. Drug retailers in our study did not demonstrate adequate understanding of the disease processes in question to justify their use of these drugs. Risks of such indiscretion include harm to individual patients as well as spread of antimicrobial resistance. More intensive efforts to educate drug retailers on their role in dispensing, along with increased enforcement of existing regulations, must be pursued.
Fascioliasis: sonographic abnormalities of the biliary tract and evolution after treatment with triclabendazole
Authors: Richter Joachim , Freise Stefan , Mull Robert , Millán Juan C. ,   Triclabendazole Clinical Study Group
Published: March 2003

Summary Diagnosis of infection with the liver fluke Fasciola hepatica is usually difficult. Ultrasonography (US) might be a useful diagnostic alternative, and we assessed the value of sequential US in the diagnosis and monitoring of fascioliasis in 76 patients at baseline and for 60 days after treatment with triclabendazole. At baseline, biliary abnormalities were observed in 52 patients. Crescent‐shaped parasites were seen in 11 patients; in 2 cases parasites were spontaneously moving and in 4 patients parasites were motionless. Postprandial examination revealed parasites adhering to the gallbladder wall in a further 5 cases. In 3 further cases, gallbladder contents were mobile but did not sediment downwards after patients changed position. Non‐specific abnormalities were: impaired gallbladder contractility (n= 23), gallbladder tenderness (n= 19), debris (n= 6), calculi (n= 5), wall thickening (n= 2) and bile duct dilatation (n= 12). During day 1–7, Fasciola‐like crescents in the gallbladder or passing through the bile duct were detected in another 15 patients, impaired gallbladder contractility in 16, gallbladder tenderness in 16, and bile duct dilatation in an additional 28 patients. Thirty‐two patients with these US abnormalities experienced colic‐like abdominal pain accompanied by increased alkaline phosphatase in 25 cases. During day 30–60, abnormalities regressed completely in 45 patients; 2/6 triclabendazole failures were evident by detection of living parasites. Biliary tract abnormalities are frequently observed by US, but the detection‐rate of Fasciola hepatica is disappointingly low despite the parasite's relatively large size. US findings must therefore be interpreted together with other clinical measurements. The visualization of parasites being expelled through the dilated common bile duct allowed the causal interpretation of post‐therapeutic abdominal pain and increase of liver enzymes. When triclabendazole is given on suspicion, visualization of worm expulsion and bile duct dilatation by US may be used to confirm diagnosis.
Trachoma: Can trichiasis be treated with a sticking‐plaster? A randomized clinical trial in China
Authors: Graz B. , Xu J. M. , Yao Z. S. , Han S. R. , Kok A. 
Published: March 2003

Trachoma is the most frequent cause of preventable blindness in the world. At the trichiasis/entropion stage, lid surgery is recommended, but many patients only use epilation, which does not prevent loss of vision. We developed a new treatment that should be more accessible than lid surgery and more effective than epilation: a sticking plaster that forces eyelashes back to their correct position. The first randomized controlled trial was conducted in Shanghai with 57 patients to compare the plaster method with epilation. After 3 months of follow‐up, with no attrition, 67% of those treated by the new method presented a good clinical status, vs none of those treated by epilation (P < 0.001). The new treatment was well tolerated and lid function remained normal. Although our results show overwhelming benefit of this new, simple treatment for trachoma at the trichiasis stage, more research is needed at the primary health care level and in other settings to determine the potential use of the new method on a large scale and by nonspecialists.RésuméLa trachome est la première cause de cécitéévitable dans le monde, avec 146 millions de personnes atteintes. Au stade trichiasis/entropion, le traitement chirurgical est recommandé, mais pour beaucoup de patients l'épilation des cils reste le seul traitement, insuffisant pour éviter la perte de la vue. Nous avons développé une nouvelle méthode de traitement, qui se veut plus accessible que la chirurgie et plus efficace que l'épilation: la contention des cils par un sparadrap double‐face. Le premier essai clinique randomisé est présenté, comparant le nouveau traitement à l'épilation, conduit à Shanghai en milieu universitaire avec 57 patients. Après trois mois de suivi, sans perte, 67% des patients traités par contention avaient un status oculaire clinique bon, contre 0% dans le groupe épilation (P < 0.001). Le traitement par contention est bien toléré et il permet de battre des cils normalement. Nos résultats démontrent donc l'efficacité de ce nouveau traitement du trachome au stade trichiasis, d'usage simple et bon marché. Des essais dans des centres de soins primaires et dans d'autres cultures sont nécessaires pour préciser l'usage possible du nouveau traitement par des non‐spécialistes et sur une large échelle.
Severe anaemia in Zambian children with Plasmodium falciparum malaria
Authors: Biemba Godfrey , Dolmans Dennis , Thuma Philip E. , Weiss Günter , Gordeuk Victor R. 
Published: March 2003

Summary Background   Severe anaemia and cerebral malaria are highly prevalent complications of Plasmodium falciparum malaria among African children. The mechanisms of severe malarial anaemia, and the relative importance of this condition in comparison to cerebral malaria, are not known for many regions of Africa. Methods   We reviewed the records of 6200 children up to 6 years of age admitted to one rural Zambian hospital between 1994 and 1996. Severe malarial anaemia was defined as an haemoglobin concentration < 5.0 g/dl in a patient with asexual forms of P. falciparum in the peripheral blood. Cerebral malaria was defined as impaired consciousness (Blantyre coma score < 5) not attributable to any other cause in a patient with a positive malaria smear. Results   Severe malarial anaemia was found in 590 children (9.5% of paediatric admissions) and strictly defined cerebral malaria occurred in 286 children (4.6% of paediatric admissions); 98 of these patients had the combination of both complications. Severe malarial anaemia correlated strongly with the degree of parasitaemia, with malnutrition as indicated by low weight for age, with absence of fever and with presentation late in the malaria season. In comparison, patients with cerebral malaria were more often febrile and presented earlier in the malaria season. The case fatality rate of severe malarial anaemia (0.088) was about half that of cerebral malaria (0.189), but because severe malarial anaemia was more common, these two forms of complicated malaria were implicated in similar numbers of in‐hospital paediatric deaths. Conclusion   Severe anaemia is a more common complication of P. falciparum malaria in hospitalized Zambian children than cerebral malaria and is associated with a similar number of deaths. Malnutrition and changes in immune response patterns due to prolonged exposure to P. falciparum may contribute to the development of this complication.
Chloroquine‐ and sulfadoxine‐pyrimethamine‐resistant falciparum malaria in vivo– a pilot study in rural Zambia
Authors: Bijl Heico M. , Kager Joost , Koetsier David W. , van der Werf Tjip S. 
Published: March 2003

Summary background  Chloroquine (CQ) and Sulfadoxine‐Pyrimethamine (SP) are the predominantly used antimalarials in Zambia and other parts of East Africa, but increasing resistance of P. falciparum is a major concern. methods  Seventy consecutive patients with uncomplicated falciparum malaria were enrolled. In 43 patients, no prior CQ use could be demonstrated by history and urianalysis (qualitative test, Dill & Glazko) and these patients were given CQ; the other 27 had taken CQ before and received SP. results  Combined R‐II and R‐III CQ‐resistance was 58% (60% in under‐fives), which is the range previously reported from Zambia. By contrast, SP‐resistance (R‐II and R‐III) was much higher (26%) than previously reported (3% – 17%). The history of prior CQ intake correlated well with the results of the Dill–Glazko test; there was no evidence for prior SP intake to explain these results. conclusion  If our findings of SP resistance are confirmed, other drugs such as quinine, atovaquone/proguanil and artemisinin are required to treat malaria in Zambia.
Impact on perinatal mortality of missed opportunities to treat maternal syphilis in rural South Africa: baseline results from a clinic randomized controlled trial
Authors: Rotchford Karen , Lombard Carl , Zuma Khangelani , Wilkinson David 
Published: March 2003

Summary objective  To demonstrate the impact on perinatal mortality of inadequate treatment for maternal syphilis despite adequate screening. method  In 12 clinics providing antenatal care in Hlabisa, South Africa 1783 pregnant women were screened for syphilis at their first antenatal visit between June and October 1998. Pregnancy outcome was determined among those with syphilis. results  A total of 158 women were diagnosed with syphilis: prevalence 9% (95% CI 8–10%). Mean gestation at first antenatal visit was 24 weeks. Thirty women (19%) received no treatment and 96 (61%) received all three recommended doses of penicillin. Among those receiving at least one dose, mean delay to the first dose was 20 days. Among those fully treated mean delay to treatment completion was 34 days. Pregnancy outcome was known for 142 women (90%) and there were 17 perinatal deaths among 15 women (11%). Eleven of 43 women (26%) who received one or fewer doses of penicillin experienced a perinatal death whilst only four of 99 women (4%) who received two or more doses of penicillin did so (P = 0.0001). Protection from perinatal death increased with the number of doses of penicillin: linear modelling suggests that one dose reduced the risk by 41%, two doses by 65% and three doses by 79%, compared with no doses. A dose‐specific, categorical model confirmed reduction in risk by 79% for all three doses. conclusion  Despite effective screening, many pregnant women with syphilis remain inadequately treated, resulting in avoidable perinatal mortality. Delays in starting and finishing treatment, as well as incomplete treatment occur. Near‐patient syphilis testing in the antenatal clinic with early treatment could improve treatment of syphilis and reduce perinatal mortality, and a randomized trial to test this is underway.