bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between small antisense RNAs and aberrant RNAs associated with sense transgene mediated gene silencing in tomato
Authors: Han Yuanhuai , Grierson Don
Published: March 2003

We investigated the occurrence and properties of small sense and antisense RNAs and aberrant transcripts in transgenic tomato plants exhibiting post‐transcriptional silencing of the endogenous polygalacturonase (PG) sense gene and a truncated homologous transgene. Small antisense RNAs, about 23 nucleotides in size, were present in the leaves and immature green fruit where the transgene was transcribed in the absence of transcripts from the fruit ripening‐specific endogenous PG gene. This suggests that the small antisense RNAs were produced from the transgene, which was supported by their failure to hybridise with the 3′ half of the endogenous PG gene, the region that was excluded from the transgene. The features of two aberrant RNAs, corresponding to the 5′ and 3′ halves of the endogenous gene, strongly suggest that they arise by endonucleolytic cleavage of endogenous PG mRNA. The region where cleavage occurs is associated with the preferential production of small RNAs from the 3′ end of the transgene. These results suggest a model where small antisense RNAs generated from the 3′ end of the transgene anneal to the endogenous mRNA, resulting in cleavage at or near the annealing regions.
The Arabidopsis gain‐of‐function mutant dll1 spontaneously develops lesions mimicking cell death associated with disease
Authors: Pilloff Rachel K. , Devadas Sendil K. , Enyedi Alexander , Raina Ramesh
Published: March 2003

We describe the characterization of a novel gain‐of‐function Arabidopsis mutant, dll1 (disease‐like lesions1), which spontaneously develops lesions mimicking bacterial speck disease and constitutively expresses biochemical and molecular markers associated with pathogen infection. Despite the constitutive expression of defense‐related responses, dll1 is unable to suppress the growth of virulent pathogens. However, dll1 elicits normal hypersensitive response in response to avirulent pathogens, thus indicating that dll1 is not defective in the induction of normal resistance responses. The lesion+ leaves of dll1 support the growth of hrcC mutant of Pseudomonas syringae, which is defective in the transfer of virulence factors into the plant cells, and therefore non‐pathogenic to wild‐type Col‐0 plants. This suggests that dll1 intrinsically expresses many of the cellular processes that are required for pathogen growth during disease. Epistasis analyses reveal that salicylic acid and NPR1 are required for lesion formation, while ethylene modulates lesion development in dll1, suggesting that significant overlap exist between the signalling pathways leading to resistance‐ and disease‐associated cell death. Our results suggest that host cell death during compatible interactions, at least in part, is genetically controlled by the plant and DLL1 may positively regulate this process.
Interactions between sterol biosynthesis genes in embryonic development of Arabidopsis
Authors: Schrick Kathrin , Mayer Ulrike , Martin Gottfried , Bellini Catherine , Kuhnt Christine , Schmidt Jürgen , Jürgens Gerd
Published: March 2003

The sterol biosynthesis pathway of Arabidopsis produces a large set of structurally related phytosterols including sitosterol and campesterol, the latter being the precursor of the brassinosteroids (BRs). While BRs are implicated as phytohormones in post‐embryonic growth, the functions of other types of steroid molecules are not clear. Characterization of the fackel (fk) mutants provided the first hint that sterols play a role in plant embryogenesis. FK encodes a sterol C‐14 reductase that acts upstream of all known enzymatic steps corresponding to BR biosynthesis mutants. Here we report that genetic screens for fk‐like seedling and embryonic phenotypes have identified two additional genes coding for sterol biosynthesis enzymes: CEPHALOPOD (CPH), a C‐24 sterol methyl transferase, and HYDRA1 (HYD1), a sterol C‐8,7 isomerase. We describe genetic interactions between cph, hyd1 and fk, and studies with 15‐azasterol, an inhibitor of sterol C‐14 reductase. Our experiments reveal that FK and HYD1 act sequentially, whereas CPH acts independently of these genes to produce essential sterols. Similar experiments indicate that the BR biosynthesis gene DWF1 acts independently of FK, whereas BR receptor gene BRI1 acts downstream of FK to promote post‐embryonic growth. We found embryonic patterning defects in cph mutants and describe a GC–MS analysis of cph tissues which suggests that steroid molecules in addition to BRs play critical roles during plant embryogenesis. Taken together, our results imply that the sterol biosynthesis pathway is not a simple linear pathway but a complex network of enzymes that produce essential steroid molecules for plant growth and development.
Disruption of the Arabidopsis AtKu80 gene demonstrates an essential role for AtKu80 protein in efficient repair of DNA double‐strand breaks in vivo
Authors: West Christopher E. , Waterworth Wanda M. , Story Geraint W. , Sunderland Paul A. , Jiang Qing , Bray Clifford M.
Published: March 2003

Double‐strand breaks (DSBs) in DNA may occur spontaneously in the cell or be induced experimentally by γ‐irradiation, and represent one of the most serious threats to genomic integrity. Non‐homologous end joining (NHEJ) rather than homologous recombination appears to be the major pathway for DSB repair in humans and plants, and it may also be the major route whereby T‐DNA integrates into the plant genome during cell transformation. In yeast and mammals, the exposed ends of damaged DNA are bound with high affinity by a dimer of Ku70 and Ku80 proteins, which protects the ends from exonucleases and juxtaposes the two ends of the DSB, independent of sequence homology. Here we report the functional characterization of Ku70 and Ku80 from Arabidopsis thaliana, and demonstrate that AtKu80 and AtKu70 form a heterodimer with DNA binding activity that is specific for DNA ends. An atku80 knockout mutant shows hypersensitivity to the DNA‐damaging agents menadione and bleomycin, consistent with a role for AtKu80 in the repair of DSBs in vivo in Arabidopsis.
The VERNALIZATION INDEPENDENCE 4 gene encodes a novel regulator of FLOWERING LOCUS C
Authors: Zhang Hua , Van Nocker Steven
Published: March 2003

The late‐flowering, vernalization‐responsive habit of many Arabidopsis ecotypes is mediated predominantly through repression of the floral programme by the FLOWERING LOCUS C (FLC) gene. To better understand this repressive mechanism, we have taken a genetic approach to identify novel genes that positively regulate FLC expression. We identified recessive mutations in a gene designated VERNALIZATION INDEPENDENCE 4 (VIP4), that confer early flowering and loss of FLC expression in the absence of cold. We cloned the VIP4 gene and found that it encodes a highly hydrophilic protein with similarity to proteins from yeasts, Drosophila, and Caenorhabditis elegans. Consistent with a proposed role as a direct activator of FLC, VIP4 is expressed throughout the plant in a pattern similar to that of FLC. However, unlike FLC, VIP4 RNA expression is not down‐regulated in vernalized plants, suggesting that VIP4 is probably not sufficient to activate FLC, and that VIP4 is probably not directly involved in a vernalization mechanism. Epistasis analysis suggests that VIP4 could act in a separate pathway from previously identified FLC regulators, including FRIGIDA and the autonomous flowering promotion pathway gene LUMINIDEPENDENS. Mutants lacking detectable VIP4 expression flower earlier than FLC null mutants, suggesting that VIP4 regulates flowering‐time genes in addition to FLC. Floral morphology is also disrupted in vip4 mutants; thus, VIP4 has multiple roles in development.
TIR‐X and TIR‐NBS proteins: two new families related to disease resistance TIR‐NBS‐LRR proteins encoded in Arabidopsis and other plant genomes
Authors: Meyers Blake C. , Morgante Michele , Michelmore Richard W.
Published: March 2003

The Toll/interleukin‐1 receptor (TIR) domain is found in one of the two large families of homologues of plant disease resistance proteins (R proteins) in Arabidopsis and other dicotyledonous plants. In addition to these TIR‐NBS‐LRR (TNL) R proteins, we identified two families of TIR‐containing proteins encoded in the Arabidopsis Col‐0 genome. The TIR‐X (TX) family of proteins lacks both the nucleotide‐binding site (NBS) and the leucine rich repeats (LRRs) that are characteristic of the R proteins, while the TIR‐NBS (TN) proteins contain much of the NBS, but lack the LRR. In Col‐0, the TX family is encoded by 27 genes and three pseudogenes; the TN family is encoded by 20 genes and one pseudogene. Using massively parallel signature sequencing (MPSS), expression was detected at low levels for approximately 85% of the TN‐encoding genes. Expression was detected for only approximately 40% of the TX‐encoding genes, again at low levels. Physical map data and phylogenetic analysis indicated that multiple genomic duplication events have increased the numbers of TX and TN genes in Arabidopsis. Genes encoding TX, TN and TNL proteins were demonstrated in conifers; TX and TN genes are present in very low numbers in grass genomes. The expression, prevalence, and diversity of TX and TN genes suggests that these genes encode functional proteins rather than resulting from degradation or deletions of TNL genes. These TX and TN proteins could be plant analogues of small TIR‐adapter proteins that function in mammalian innate immune responses such as MyD88 and Mal.
Acyl CoA profiles of transgenic plants that accumulate medium‐chain fatty acids indicate inefficient storage lipid synthesis in developing oilseeds
Authors: Larson Tony R. , Edgell Teresa , Byrne James , Dehesh Katayoon , Graham Ian A.
Published: March 2003

Several Brassica napus lines transformed with genes responsible for the synthesis of medium‐ or long‐chain fatty acids were examined to determine limiting factor(s) for the subsequent accumulation of these fatty acids in seed lipids. Examination of a decanoic acid (10:0) accumulating line revealed a disproportionately high concentration of 10:0 CoA during seed development compared to long‐chain acyl CoAs isolated from the same tissues, suggesting that poor incorporation of 10:0 CoA into seed lipids limits 10:0 fatty acid accumulation. This relationship was also seen for dodecanoyl (12:0) CoA and fatty acid in a high 12:0 line, but not for octadecanoic (18:0) CoA and fatty acid in a high 18:0 line. Comparison of 10:0 CoA and fatty acid proportions from seeds at different developmental stages for transgenic B. napus and Cuphea hookeriana, the source plant for the medium‐chain thioesterase and 3‐ketoacyl‐ACP synthase transgenes, revealed that C. hookeriana incorporates 10:0 CoA into seed lipids more efficiently than transgenic B. napus. Furthermore, β‐oxidation and glyoxylate cycle activities were not increased above wild type levels during seed development in the 8:0/10:0 line, suggesting that lipid catabolism was not being induced in response to the elevated 10:0 CoA concentrations. Taken together, these data suggest that transgenic plants that are engineered to synthesize medium‐chain fatty acids may lack the necessary mechanisms, such as specific acyltransferases, to incorporate these fatty acids efficiently into seed lipids.
SAD: a new DOF protein from barley that activates transcription of a cathepsin B‐like thiol protease gene in the aleurone of germinating seeds
Authors: Isabel‐LaMoneda Inés , Diaz Isabel , Martinez Manuel , Mena Montaña , Carbonero Pilar
Published: March 2003

Functional analysis of hydrolase gene promoters, induced by gibberellin (GA) in aleurone cells following germination, has identified a GA‐responsive complex (GARC) as a tripartite element containing a pyrimidine‐box motif 5′‐CCTTTT‐3′. We describe here the characterization of a new barley gene (Sad gene) encoding a transcription factor (SAD) of the DNA binding with One Finger (DOF) class that binds to the pyrimidine box in vitro and activates transcription of a GA‐induced protease promoter in bombarded aleurone layers. RT‐PCR and in situ hybridization analyses showed that the Sad transcripts accumulated in all tissues analysed, being especially abundant in the scutellum and aleurone cells upon seed germination. The SAD protein, expressed in bacteria, binds in a specific manner to two oligonucleotides containing the sequence 5′‐G/CCTTTT/C‐3′, derived from the promoter region of the Al21 gene encoding a cathepsin B‐like cysteine protease. Although the Sad transcript accumulation did not respond to external GA‐incubation in aleurone cells, in transient expression experiments in co‐bombarded aleurone layers, SAD trans‐activated transcription from the Al21 promoter in a similar manner as did GAMYB, a MYB protein previously shown to respond to GA and to activate several hydrolase gene promoters in barley aleurone cells. In vivo interaction between the GAMYB and SAD proteins was shown in the yeast two‐hybrid system, where GAMYB potentiates the SAD trans‐activation capacity through interaction with its C‐terminal domain.
Functional complementation in yeast reveals a protective role of chloroplast 2‐Cys peroxiredoxin against reactive nitrogen species
Authors: Sakamoto Atsushi , Tsukamoto Shigefumi , Yamamoto Hiroshi , Ueda–Hashimoto Manami , Takahashi Misa , Suzuki Hitomi , Morikawa Hiromichi
Published: March 2003

The importance of nitric oxide (NO) as a signaling molecule to various plant physiological and pathophysiological processes is becoming increasingly evident. However, little is known about how plants protect themselves from nitrosative and oxidative damage mediated by NO and NO‐derived reactive nitrogen species (RNS). Peroxynitrite, the product of the reaction between NO and superoxide anion, is considered to play a central role in RNS‐induced cytotoxicity, as a result of its potent ability to oxidize diverse biomolecules. Employing heterologous expression in bacteria and yeast, we investigated peroxynitrite‐scavenging activity in plants of 2‐Cys peroxiredoxin (2CPRX), originally identified as a hydroperoxide‐reducing peroxidase that is ubiquitously distributed among organisms. The putative mature form of a chloroplast‐localized 2CPRX from Arabidopsis thaliana was overproduced in Escherichia coli as an amino‐terminally hexahistidine‐tagged fusion protein. The purified recombinant 2CPRX, which was catalytically active as peroxidase, efficiently prevented the peroxynitrite‐induced oxidation of a sensitive compound. We also examined in vivo the ability of the Arabidopsis 2CPRX to complement the 2CPRX deficiency of a Saccharomyces cerevisiae mutant. Functional expression in the mutant strain of the Arabidopsis 2CPRX not only increased cellular tolerance to hydrogen peroxide, but also complemented the hypersensitive growth defect induced by nitrite‐mediated cytotoxicity. The complemented cells significantly enhanced the capacity to reduce RNS‐mediated oxidative damages. The results presented here demonstrate a new role of plant 2CPRX as a critical determinant of the resistance to RNS, and support the existence of a plant enzymatic basis for RNS metabolism.
The biology and clinical applications of dendritic cells
Authors: Reid
Published: March 2003

Dendritic cells (DC) have an essential role in the induction of immune responses to antigen by naive T cells. As ‘professional’ antigen‐presenting cells they are specialized to take up, process and present soluble antigens in complexes with either class I or class II MHC molecules. They are present in only trace numbers in most tissues and in a relatively immature state but, in the presence of inflammatory signals, they rapidly take up foreign antigens and undergo maturation into potent antigen‐presenting cells that migrate to secondary lymphoid tissue where they initiate an immune response. It is now possible to expand populations of DC in vitro both from primitive haemopoietic progenitors as well as from more mature peripheral blood mononuclear cells. This has shed light on many developmental aspects of DC biology and furthered our knowledge of the mechanisms of antigen processing and presentation. It is clear that there is more than one pathway of DC differentiation and that some DC may actually induce immunological unresponsiveness — a possible mechanism for tolerance to self‐antigens. For clinicians the most exciting prospect is of their use as cellular adjuvants to generate beneficial responses to antigens of low immunogenicity such as tumour antigens. This review outlines aspects of human DC development and the way in which a greater understanding of their biology may lead to promising clinical applications.
Use of a phycoerythrin‐conjugated anti‐glycophorin A monoclonal antibody as a double label to improve the accuracy of FMH quantification by flow cytometry
Authors: Lloyd‐Evans  , Guest  , Austin  , Scott
Published: March 2003

The use of flow cytometry for quantifying fetomaternal haemorrhage is increasing, and has been shown to be more accurate than the Kleihauer–Betke test for evaluating larger bleeds of over 4 mL in volume. Red cells are stained with fluorescently labelled monoclonal anti‐D. Cells for analysis are normally gated manually on the basis of forward and side scatter. We investigated whether the use of an antiglycophorin A monoclonal antibody conjugate (red cell specific) in a dual labelling technique would improve the gating of RBC and FMH quantification.

Mixes of adult rr and cord R1r RBC were prepared to simulate 1, 0.5, 0.25, 0.12 and 0.06% fetal bleeds. Phycoerythrin‐conjugated BRIC 256 (mouse monoclonal antiglycophorin A) was used to label all RBC, and FITC‐BRAD‐3 monoclonal anti‐D was used to determine the proportion of D‐positive cells. Results from the dual labelling experiments were compared to those from single labelling of the same mixtures with FITC‐BRAD‐3 alone, using gated and ungated data. The results showed that single labelling with manual gating gave falsely low FMH estimates.

We conclude that use of a fluorescently labelled antiglycophorin A antibody improves the accuracy of the FMH measurement by flow cytometry, as manual subjective gating of RBC excludes a higher proportion of fetal than of adult RBC.
Endogenous glutathione and platelet function in platelet concentrates stored in plasma or platelet additive solution
Authors: Hervig T. , Mansoor M. A. , Farstad M.
Published: March 2003

Platelet function was studied in platelet concentrates by assay of the thrombin‐induced release of endogenous serotonin and presence of the swirling phenomenon in relation to endogenous glutathione (GSH) and cysteine.

In platelets stored in plasma, addition of cysteamine resulted in only a moderate fall in GSH after 5 days of storage, from an average of 14·91 to 11·46 nmol per 109 platelets. Exogenously added GSH had no effect, and addition of buthionine sulfoximine (BSO) resulted in almost complete depletion of GSH, to an average of 0·65 nmol per 109 platelets. Addition of cysteamine or GSH resulted in increased endogenous cysteine whereas BSO had no effect.

In platelets stored in a platelet additive solution (T‐sol®), complete depletion of GSH was found in the presence of cysteamine, GSH and BSO.

Endogenous serotonin was unchanged during storage both in plasma and in additive solution (2·8 nmol per 109 platelets). Despite almost total depletion of endogenous GSH, the thrombin‐induced release of serotonin after 5 days' storage was significantly affected only in the presence of BSO in platelets stored in additive solution (mean values 72·3% vs. 63·3% of endogeneous serotonin, P < 0·05).

Similarly, addition of cysteamine or GSH had no significant effect on swirling but BSO reduced the swirling score after 5 days' storage in platelet additive solution compared with plasma. After 10 days' storage, there was a significant reduction in swirling in the concentrates where BSO was added (P < 0·05).
Improved platelet compatiblity of water vapour glow discharge treated non‐woven poly(ethylene terephthalate) leukocyte‐reduction filters for different types of platelet concentrates
Authors: Kostelijk E. H. , Klomp A. J. A. , Engbers G. H. M. , Gouwerok C. W. N. , Verhoeven A. J. , Van Aken W. G. , Feijen J. , De Korte D.
Published: March 2003

. Non‐woven poly[ethylene terephthalate] (NW‐PET) filter fabric, usually used for leucocyte removal of red cells, was modified by water vapour glow discharge (WVGD) treatment to improve platelet compatibility.

Modified filter material was evaluated with different kinds of platelet concentrates (PCs). In addition, modified filter materials were γ‐sterilized and tested after different time intervals at different storage conditions.

Modification of the filter material resulted in an improved platelet recovery after filtration of PC from 57 to about 80%. No significant difference in platelet recovery was observed when filtering either freshly prepared (79 ± 3·5%, mean ± SD), overnight‐stored single BC‐PC (78 ± 3·3%), overnight‐stored single PRP‐PC (75 ± 8·8%) or overnight‐stored pooled BC‐PC (79 ± 8·9%). However, freshly prepared pooled BC‐PC gave a significantly higher platelet recovery (84 ± 3·5%). Leukocyte depletion did not differ significantly between the different types of PC. γ‐Sterilization and subsequent storage of the modified filter material for 5, 14 and 26 weeks at 20 °C or 37 °C had no significant influence on the filtration results of overnight‐stored pooled BC‐PC.

The results of the present study show that WVGD‐treated NW‐PET is platelet compatible and can be used for leucocyte removal from preferably BC‐PC. It can be γ‐sterilized and stored for at least 6 months prior to filtration without affecting the platelet recovery and leucocyte removal.
Measurement of blood volume after haemodilution with haemoglobin‐based oxygen carriers by a radiolabelled‐albumin method
Authors: Caron A. , Mayer J.‐C. , Menu P. , Alayash A. , Marie P.‐Y. , Vigneron C.
Published: March 2003

. Recent studies have shown that the use of haemoglobin‐based oxygen‐carrying solutions (HBOCs) for perioperative haemodilution could significantly reduce the need for packed red blood cells in clinical practice. Though the effects of HBOCs on plasma volume have been characterized in experimental models of volume resuscitation from hypovolaemic shock, little is known about their action in normovolaemic haemodilution conditions. We therefore applied a radiolabelled serumalbumin method to determine blood volume after haemodilution with crosslinked or conjugated haemoglobin, in comparison with a reference solution of hydroxyethyl starch (HES). Three groups of New Zealand white rabbits were studied (n = 7 each group) subjected to moderate exchange transfusion with low molecular weight HES, bis(3,5‐dibromosalicyl)fumarate crosslinked haemoglobin (αα‐Hb), or dextran‐conjugated haemoglobin (Hb‐Dex‐BTC). HES induced no changes in heart rate and blood pressure. The amplitude and duration of blood pressure increase and bradycardia were similar in both haemoglobin groups. A significant contraction of blood volume (12%) was observed 60 min after haemodilution with αα‐Hb, compared to HES and Hb‐Dex‐BTC. At the same time point, a decrease in absolute haemoglobin (plasma haemoglobin × plasma volume) was also noted. This study suggests that in haemodilution conditions, the specific oncotic properties and circulating persistence of crosslinked and conjugated haemoglobin solutions affect the pattern of blood volume distribution differently.
Study of five cell salvage machines in coronary artery surgery
Authors: Burman J. F. , Westlake A. S. , Davidson S. J. , Rutherford L. C. , Rayner A. S. , Wright A. M. , Morgan C. J. , Pepper J. R.
Published: March 2003

Summary  We evaluated the effectiveness, ease of use and safety of five machines for blood salvage during coronary artery surgery. All were equally effective in concentrating red cells. We measured haemoglobin, packed cell volume, free haemoglobin, white cells, neutrophil elastase, platelets, thrombin–antithrombin complex (TAT), prothrombin activation peptide F1·2, fibrin degradation product (d‐dimers), tissue plasminogen activator (tPA) and heparin in wound blood, in washed cell suspensions and in a unit of bank blood prepared for each patient. All machines were equally safe and easy to use and were equally effective in removing heparin and the physiological components measured. There were no adverse effects on patients. Clotting factors are severely depleted both in salvaged blood, even before washing, and in bank blood. Cell savers are a valuable adjunct to coronary artery surgery, but careful monitoring of coagulation is required when the volumes of either bank blood or salvaged blood are large.
Evaluation of the 3D BacT/ALERT automated culture system for the detection of microbial contamination of platelet concentrates
Authors: McDonald C. P. , Rogers A. , Cox M. , Smith R. , Roy A. , Robbins S. , Hartley S. , Barbara J. A. J. , Rothenberg S. , Stutzman L. , Widders G.
Published: March 2003

Summary Bacterial transmission remains the major component of morbidity and mortality associated with transfusion‐transmitted infections. Platelet concentrates are the most common cause of bacterial transmission.

The BacT/ALERT 3D automated blood culture system has the potential to screen platelet concentrates for the presence of bacteria. Evaluation of this system was performed by spiking day 2 apheresis platelet units with individual bacterial isolates at final concentrations of 10 and 100 colony‐forming units (cfu) mL−1. Fifteen organisms were used which had been cited in platelet transmission and monitoring studies. BacT/ALERT times to detection were compared with thioglycollate broth cultures, and the performance of five types of BacT/ALERT culture bottles was evaluated. Sampling was performed immediately after the inoculation of the units, and 10 replicates were performed per organism concentration for each of the five types of BacT/ALERT bottles.

The mean times for the detection of these 15 organisms by BacT/ALERT, with the exception of Propionibacterium acnes, ranged from 9·1 to 48·1 h (all 10 replicates were positive). In comparison, the time range found using thioglycollate was 12·0–32·3 h (all 10 replicates were positive). P. acnes' BacT/ALERT mean detection times ranged from 89·0 to 177·6 h compared with 75·6–86·4 h for the thioglycollate broth.

BacT/ALERT, with the exception of P. acnes, which has dubious clinical significance, gave equivalent or shorter detection times when compared with the thioglycollate broth system. The BacT/ALERT system detected a range of organisms at levels of 10 and 100 cfu mL−1. This study validates the BacT/ALERT microbial detection system for screening platelets. Currently, the system is the only practically viable option available for routinely screening platelet concentrates to prevent bacterial transmission.
IgG4 serology of loiasis in three villages in an endemic area of south‐eastern Gabon
Authors: Touré Fousseyni S. , Egwang Thomas G. , Millet Pascal , Bain Odile , Georges Alain J. , Wahl Goetz
Published: March 2003

Human filariasis due to Loa loa differs from other filariasis in that the majority of infected subjects are without circulating microfilariae (occult loiasis). In search for alternative diagnostic methods, which do not depend on circulating microfilariae or the (rather infrequent) eye‐passage of adult worms, it was shown earlier that IgG4 antibodies directed against Loa loa adult worm antigen are apparently a good marker of occult loiasis and specific with regard to the sympatrically occurring Mansonella perstans. In this study we evaluated an IgG4 antibody‐based ELISA using crude extract of Loa loa microfilariae (which is easier to obtain than adult worm) to estimate the prevalence of loiasis in 3 villages in South‐East Gabon. Of 222 examined individuals (80 children < 16 years, 142 adults) 44 (20%) carried Loa loa microfilariae and 170 (77%) M. perstans. Using the mean OD‐value + 1 standard deviation of 9 sera from patients solely infected with M. perstans (from the Gambia, where Loa loa is not endemic) as a cut‐off, 35 of the 44 microfilaraemic Loa loa patients and 2 of the 9 Gambian controls were positive. This shows that our method had a sensitivity of 80% and a specificity of 78%. Among the remaining 178 subjects who had no microfilariae of Loa loa, as many as 97 (55%) had significant levels of specific IgG4 antibodies against Loa loa, suggesting that they carried occult loiasis. The mean IgG4 level in these putatively occult loiasis patients was slightly but significantly lower than in microfilaraemic subjects (P < 0.03). In conclusion, despite the limited sensitivity and specificity of our method, IgG4‐ ELISA at present is a very useful tool in estimating the real prevalence of loiasis in epidemiological surveys and at the individual level can confirm the diagnosis of L. loa amicrofilaraemic subjects with clinical signs suggesting loiasis.
Geophagy, iron status and anaemia among primary school children in Western Kenya
Authors: Geissler P. Wenzel , Mwaniki David L. , Thiong'o Frederick , Michaelsen Kim F. , Friis Henrik
Published: March 2003

As part of a cross‐sectional study among 156 primary school children (median age 13 years, range 10–18) in Western Kenya, geophagy was assessed through interviews. 114 (73.1%) of these children reported eating soil daily. Haemoglobin levels were determined in all 156 children and serum ferritin concentrations in 135. The mean haemoglobin (Hb) concentration was 12.7 g/dl, and median ferritin concentration 27.2 μg/l. Both the proportion of anaemic (Hb < 11.0 g/dl) and of iron‐depleted (ferritin < 12 μg/l) children was significantly higher among the geophageous children than among the nongeophageous (9.6%vs. 0% anaemia; P= 0.037; 18.4%vs. 5.4% iron depletion; P= 0.046). Serum ferritin and haemoglobin concentrations were not correlated (r= 0. 13 5; P= 0. 100). Multiple regression analysis showed that geophagy, hookworm eggs per gram faeces and malaria parasite counts per μl blood were independent predictors of serum ferritin, when controlling for other helminth infections, age and sex, and socio‐economic and educational background of the children's families and family size (y = 36.038–11.247(geophagy) – 0.010(hookworm epg) + 0.001(malaria parasite counts); R2 = 0.17). Multiple regression analysis with haemoglobin as dependent variable and the same independent variables did not reveal any significant predictors. Analysis of the soil eaten by the children revealed a mean HCl‐extractable iron content of 168.9 mg/kg (SD 44.9). Based on the data on the amounts eaten daily and this mean iron content, soil could provide on average 4.7 mg iron to a geophageous child (interquartile range 2.1–7.1 mg), which is equivalent to 32% of the Recommended Nutrient Intake (RNI) for girls (interquartile range 14–48%) or 42% of the RNI for boys (interquartile range 19–63%). Iron depletion and anaemia are associated with geophagy, but only serum ferritin concentrations were shown to be dependent upon geophagy in the regression model. From the cross‐sectional data no inference about causality can be made. To clarify the possible causal relationships involved, longitudinal studies and iron‐supplementation intervention studies are needed.
Seroprevalence of viral hepatitis in Tanzanian adults
Authors: Miller  , Miller  , Shao  , Weaver  , Shimokura  , Paul  , Lallinger
Published: March 2003

In a cross‐sectional study in Dar es Salaam, Tanzania, we determined the seroprevalence of markers for hepatitis A, B, C and E viruses and examined associated risk markers. Among 403 healthy adults, the seroprevalence of antibodies to hepatitis A virus was 99.0% (95% confidence interval: 97.5–99.7). Prior exposure to hepatitis C and E viruses was rare (hepatitis C: 0.7% (0.2–2.1); hepatitis E: 0.2% (< 0.1–1.4)). The prevalence of all markers of hepatitis B was 70.7% (66.0–75.1). Hepatitis B surface antigen was identified in 6.0% (3.9–8.7) of subjects. Independent predictors of hepatitis B infection identified by logistic regression included older age, male gender, Muslim religion and type of abode. Given the high prevalence of hepatitis B and the low prevalence of hepatitis C, the majority of chronic viral hepatitis is likely to be associated with hepatitis B. Control efforts should focus primarily on hepatitis B.
Deriving meteorological variables across Africa for the study and control of vector‐borne disease: a comparison of remote sensing and spatial interpolation of climate
Authors: Hay S. I. , Lennon J. J.
Published: March 2003

SummaryThis paper presents the results of an investigation into the utility of remote sensing (RS) using meteorological satellites sensors and spatial interpolation (SI) of data from meteorological stations, for the prediction of spatial variation in monthly climate across continental Africa in 1990. Information from the Advanced Very High Resolution Radiometer (AVHRR) of the National Oceanic and Atmospheric Administration's (NOAA) polar‐orbiting meteorological satellites was used to estimate land surface temperature (LST) and atmospheric moisture. Cold cloud duration (CCD) data derived from the High Resolution Radiometer (HRR) on‐board the European Meteorological Satellite programme's (EUMETSAT) Meteosat satellite series were also used as a RS proxy measurement of rainfall. Temperature, atmospheric moisture and rainfall surfaces were independently derived from SI of measurements from the World Meteorological Organization (WMO) member stations of Africa. These meteorological station data were then used to test the accuracy of each methodology, so that the appropriateness of the two techniques for epidemiological research could be compared. SI was a more accurate predictor of temperature, whereas RS provided a better surrogate for rainfall; both were equally accurate at predicting atmospheric moisture. The implications of these results for mapping short and long‐term climate change and hence their potential for the study and control of disease vectors are considered. Taking into account logistic and analytical problems, there were no clear conclusions regarding the optimality of either technique, but there was considerable potential for synergy.
Feasibility of a rapid dipstick antigen‐capture assay for self‐testing of travellers' malaria
Authors: Trachsler Matthias , Schlagenhauf Patricia , Steffen Robert
Published: March 2003

SummaryThis open comparative study sought to determine whether, and with what level of instruction, travellers can successfully use and interpret the rapid whole blood malaria diagnostic test, ParaSight F. 160 visitors to the Zürich University Travel Clinic took part in the study. One group received written instructions only, while another group was given combined oral and written instructions on how to test their own blood for malaria infection and interpret a series of 5 prepared test strips. Each volunteer also completed a questionnaire targeted at assessing performance in using the diagnostic, interpretation of the results and acceptability of the concept of self‐testing for malaria infection. The main outcome measures were successful performance of the test, correct interpretation of prepared test strips and acceptability of the test. In the group which received only written instructions, 60/80 (75%) were successful, whilst in the group which received written and oral instructions, 72/80 (90%) successfully performed the test (P < 0.02). Overall, 565 (70.6%) test strips were correctly and 165 (20.6%) incorrectly interpreted with 113 (14.1%) false negative interpretations. No prepared test strip was interpreted as false positive. Seventy (8.8%) test strips were not interpreted. Some 91.9% of all candidates would use such a test if it were available. While it is possible for lay persons to successfully perform the test, interpretation of results poses a problem. In particular, the proportion of false negative interpretations is unacceptable. A combination of written and oral instructions leads to a significantly higher level of successful test performance. If such a test is to be made available to the general public, written instructions must be made concise and foolproof and the test endpoint clearly defined, as the currently available test is more suitable for trained laboratory personnel. In the meantime other candidate diagnostics have become available and these should now be assessed for their suitability in the context of travellers' malaria.
Dogmas and misunderstandings in East Coast fever
Authors: Dolan Thomas T.
Published: March 2003

Summary East Coast fever (ECF) is the most important tick‐borne disease in eastern, central and southern Africa and caused an estimated loss of US $186 million in 1989 in the 11 countries where it occurs. It was brought to southern Africa with cattle from Tanzania in 1901 and, over the next 3 years, devastated the cattle that had survived the rinderpest pandemic of the 1890s. Chemical control of ticks using arsenical compounds was introduced in the early 1900s and became the main control measure for both ticks and the diseases they transmit. This method of control has become less reliable over the last 30 years for many reasons, including reduced government spending on livestock and extension, the cost of acaricides, acaricide resistance, poor management of dips and spray races, and poor application of cattle movement control and quarantine. Significant advances in immunization and treatment have been made in the last 30 years, and more robust integrated strategies combining immunization, reduced frequency of chemical control and treatment are being adopted or considered. Throughout its history, ECF has been a source of great anxiety and cost to farmers, and of intense interest to research workers. Many dogmas and misconceptions have become established, some of which still flourish while others took years to demolish. This paper briefly reviews these as well as the history of the disease and explores recent epidemiological findings and their relevance to applying effective control.
Decline of mortality in children in rural Gambia: the influence of village‐level Primary Health Care
Authors: Hill A. G. , MacLeod W. B. , Joof D. , Gomez P. , Walraven G.
Published: March 2003

Summary Using data from a longitudinal study conducted in 40 villages by the UK MRC in the North Bank Division of The Gambia beginning in late 1981, we examined infant and child mortality over a 15‐year period for a population of about 17 000 people. Comparisons are drawn between villages with and without PHC. The extra facilities in the PHC villages include: a paid Community Health Nurse for about every 5 villages, a Village Health Worker and a trained Traditional Birth Attendant. Maternal and child health services with a vaccination programme are accessible to residents in both PHC and non‐PHC villages. The data indicate that there has been a marked improvement in infant and under‐five mortality in both sets of villages. Following the establishment of the PHC system in 1983, infant mortality dropped from 134/1000 in 1982–83 to 69/1000 in 1992–94 in the PHC villages and from 155/1000 to 91/1000 in the non‐PHC villages over the same period. Between 1982 and 83 and 1992–94, the death rates for children aged 1–4 fell from 42/1000 to 28/1000 in the PHC villages and from 45/1000 to 38/1000 in the non‐PHC villages. Since 1994, when supervision of the PHC system has weakened, infant mortality rates in the PHC villages have risen to 89/1000 in 1994–96. The rates in the non‐PHC villages fell to 78/1000 for this period. The under‐five mortality rates in both sets of villages have converged to 34/1000 for 1994–96. When the PHC programme was well supported in the 1980s, we saw significantly lower mortality rates for the 1–4‐year‐olds. These differences disappeared when support for PHC was reduced after 1994. The differential effects on infant mortality are less clear cut.
A prospective evaluation of a clinical algorithm for the diagnosis of malaria in Gambian children
Authors: Bojang K. A. , Obaro S. , Morison L. A. , Greenwood B. M.
Published: March 2003

Summary Diagnosis of clinical malaria remains difficult, especially in areas where a high proportion of the asymptomatic population have parasitaemia, for the symptoms and signs of malaria overlap with those of other common childhood diseases, such as acute lower respiratory tract infections. However, a study of symptoms and signs in a group of children who presented to Farafenni Health Centre, The Gambia with a history of recent fever identified a group of signs and symptoms which were strong predictors of malaria as opposed to other febrile illnesses. Using these predictors, an algorithm was developed which could be used by fieldworkers and which had a similar sensitivity and specificity for the diagnosis of malaria as that of an experienced paediatrician working without laboratory support. This algorithm has been validated prospectively on 518 children who presented to the Medical Research Council clinic at Basse, The Gambia with fever or a history of recent fever during a 10‐month period. A fieldworker obtained a detailed history from the parent or guardian of each child and performed a clinical examination which included measurement of axillary temperature and respiratory rate. Packed cell volume was measured and a thick smear was examined for malaria parasites. A malaria score, based on the presence or absence of malaria‐related signs and symptoms, was determined for 382 children who were seen at the clinic during the high transmission season. Using the cut‐off score which was optimal during the previous retrospective study, a sensitivity of 70% and a specificity of 77% for a diagnosis of malaria was obtained. The optimal cut‐off score for the Basse population was a score of 7; this gave a sensitivity of 88% and a specificity of 62%, figures comparable to those obtained by an experienced paediatrician without laboratory support.
Recent urban growth and urinary schistosomiasis in Niamey, Niger
Authors: Ernould J. C. , Kaman Kaman A. , Labbo R. , Couret D. , Chippaux J. P.
Published: March 2003

Summary A cluster sample survey was conducted in 1998 in 30 schools to assess the effect of the growth of Niamey during the last decade on a urinary schistosomiasis urban focus described in 1989. Two thousand and forty‐two children (11.0 + 0.1 years old) had a urine filtration test and answered a behavioural questionnaire. Snail populations of the sites used by schoolchildren were followed up in 1999. The global prevalence was 15.7% in 1998, as opposed to 23.7% in 1989. The prevalence was very low in schools far from the river and higher in those along the Niger banks, particularly in villages on the periphery of the urban area. Geographical factors were more important than socio‐economic ones in explaining the distribution of the disease. Only 46% of the children in Niamey reported water contact; mainly in the river, rarely in pools and the canal. The infection risk was low in pools (RR = 1.6), high in the river (RR = 3.5) and very high in the canal (RR = 12.5). Malacological studies confirmed the location of transmission sites obtained through parasitological studies and the questionnaire. Sixty‐one per cent of the children travelled outside Niamey to the hyperendemic surrounding areas. However, these movements did not increase their infection level. The results are discussed in relation to water contact behaviour and Schistosoma haematobium transmission features.
Percutaneous catheter drainage in drug‐resistant amoebic liver abscess
Authors: Hanna R. M. , Dahniya M. H. , Badr S. S. , El‐Betagy A.
Published: March 2003

Summary This communication records our experience with the percutaneous catheter drainage (PCD) of 22 amoebic liver abscesses in 19 patients who had failed to respond to amoebicidal therapy. In one patient with a left lobe abscess, imminent rupture was an additional indication for drainage. PCD combined with amoebicidal therapy not only expedited recovery, but was curative in all 19 patients. There were no complications. We conclude that PCD is a most useful adjunct to drug therapy and recommend its routine use in the management of drug‐resistant amoebic liver abscesses.
Specificity of circulating antigen detection for schistosomiasis mansoni in Senegal and Burundi
Authors: Polman Katja , Diakhate Meremarie M. , Engels Dirk , Nahimana Samuel , Van Dam Govert J. , Falcão Ferreira Sonja T. M. , Deelder Andre M. , Gryseels Bruno
Published: March 2003

The specificity of schistosome circulating antigen detection was determined in negative individuals from two S. mansoni‐ endemic countries, Senegal and Burundi, and compared with results from Dutch control individuals. A nearly absolute specificity was achieved for circulating anodic antigen (CAA) detection in serum, irrespective of the target population or sample pretreatment method. Circulating cathodic antigen (CCA) detection in serum and urine resulted in a lower specificity than serum CAA detection. Apparent large differences in specificity of CCA detection between countries were mainly due to pretreatment methods. Apparently, the alkaline/heating pretreatment method is not as effective as trichloroacetic acid (TCA) ‐pretreatment in removing (certain) interfering components, which may vary between populations. In view of the development of the urine CCA assay into a noninvasive screening test, a slightly lower specificity may still be acceptable. For precise epidemiological analyses the highly specific serum CAA assay remains the method of choice.
Should trichiasis surgery be offered in the village? A community randomised trial of village vs. health centre‐based surgery
Authors: Bowman R. J. C. , Sey Soma O. , Alexander N. , Milligan P. , Rowley J. , Faal H. , Foster A. , Bailey R. L. , Johnson G. J.
Published: March 2003

Summary introduction  Surgery for trachomatous trichiasis prevents blindness and is advocated by the WHO as part of the SAFE strategy for the global elimination of trachoma. We conducted a randomised community trial to investigate the effect of providing surgery in villages on surgical uptake in The Gambia.

methods  56 villages from two divisions were assigned to eight pairs of clusters matched by geographical division and proximity. One cluster from each pair was randomly assigned to receive village‐based surgery and the other cluster health centre‐based surgery. Outcome measures were uptake rates and surgical results after 1 week and 3 months. The paired t‐test was used to analyse the results.

results  Overall uptake was 66% in the village‐based clusters and 44% in the health centre‐based clusters. Subjects in the village‐based surgery arm had significantly shorter journey times (P = 0.01) and lower costs (P = 0.002). The mean difference in absolute acceptance rates of surgery was 20% better in village‐based clusters (95% CI –9 to + 49%, P = 0.15), which would equate to an improvement of 45% (95% CI −20% to 120%) on the average acceptance rates of 44% in the health centre‐based group.

conclusion  These results strongly suggest better surgical uptake when surgery is provided in patients' villages due to lower cost to the patient, time saved and less fear of the operation.