bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebral palsy, low birthweight and socio‐economic deprivation: inequalities in a major cause of childhood disability
Authors: Dolk Helen , Pattenden Sam , Johnson Ann
Published: March 2003

There is currently little and conflicting evidence concerning the existence of socio‐economic inequalities in cerebral palsy prevalence, or the extent to which this is influenced by socio‐economic inequalities in low birthweight, a strong risk factor for cerebral palsy. The study is based on 753 children registered with cerebral palsy, resident in the former Oxford Regional Health Authority area and born in the years 1984–90. Two population definitions were used: 1. Children with cerebral palsy resident at birth in the area, with resident births as denominator, 2. Children with cerebral palsy resident at age 5 in the area, with children of ages 1–7 resident in the area in the 1991 census as denominator. Children with cerebral palsy and all births/children were classified according to the Carstairs area deprivation index (grouped into quintiles) of their ward of residence. The prevalence among residents at birth varied from 2.08 per 1000 births in the most affluent quintile to 3.33 in the most deprived quintile (trend P < 0.001). Although there was a tendency for children to move to more affluent areas during early childhood, the socio‐economic gradient was similar at age 5. A greater proportion of births in the more deprived quintiles were of low or very low birthweight, the proportion rising from 5.6% in the most affluent quintile to 8.2% in the most deprived. Within the normal birthweight category there was a trend for higher prevalence of cerebral palsy in more deprived quintiles, from 1.29 per 1000 in the most affluent quintile to 2.42 in the most deprived quintile (trend P < 0.001). Within the low birthweight and very low birthweight groups, separately or combined, there was no evidence of any relationship between cerebral palsy prevalence and deprivation. We estimate that up to 17% of cerebral palsy cases might be ‘preventable’ in terms of the reduction to be expected if the whole population had the rate of cerebral palsy of the most affluent quintile. Although the strong socio‐economic gradient for cerebral palsy was restricted to the normal birthweight category, we estimate that two‐thirds of the excess cases in the population associated with greater socio‐economic deprivation were normal birthweight cases, and one‐third were low birthweight cases owing to the greater prevalence of low birthweight in more deprived populations. The pattern of socio‐economic inequalities should be further explored in other regions, and should be taken into account in aetiological research, and in the effective delivery and evaluation of services.
Cerebral palsy births in eastern Denmark, 1987–90: implications for neonatal care
Authors: Topp Monica , Uldall Peter , Greisen Gorm
Published: March 2003

The Cerebral Palsy Register in eastern Denmark has collected cases using a uniform data sampling procedure since birth year 1979. We have investigated changes in the rate of cerebral palsy, related to gestational age, mortality and perinatal risk factors in children born 1983–90. The total cerebral palsy birth prevalence decreased from 3.0 in the birth year period 1983–86 to 2.4 per 1000 live births (P < 0.01) in 1987–90, owing to a decrease among all preterm infants (29–19 per 1000, P < 0.001). The perinatal and early neonatal mortality in preterm infants was unchanged from 1983–86 to 1987–90. The rate of cerebral palsy in term infants was 1.5 per 1000 in all birth‐year periods from 1979–90. Among the cerebral palsy infants, the proportion of very preterm babies treated with mechanical ventilation in the neonatal period decreased from 95% in 1983–86 to 61% in 1987–90 (P < 0.001), while the group treated with CPAP among the moderately preterm babies increased from 61% to 78% (P < 0.05). The significant decline in cerebral palsy rate in preterm infants born 1987–90 may be due to a change in treatment at the neonatal intensive care units using less mechanical ventilation, a hypothesis which needs further investigation.
Childhood leukaemia in Costa Rica, 1981–96
Authors: Monge Patricia , Wesseling Catharina , Rodríguez Ana Cecilia , Cantor Kenneth P. , Weiderpass Elisabete , Reutfors Johan , Ahlbom Anders , Partanen Timo
Published: March 2003

Childhood leukaemia incidence in Costa Rica during 1981–96, among the highest in the world, was analysed by histology, gender, birth year, time period of diagnosis, age at diagnosis and region. Numbers of cases were extracted from the database of the National Cancer Registry (RNT) of Costa Rica. Person–years at risk were calculated from census data and post‐census population estimates. During the follow‐up, 918 cases of leukaemia in children under 15 years (510 boys, 408 girls) were reported to the RNT (41% of all childhood malignancies), with an overall age‐standardised incidence rate of 56 per million person–years. Acute lymphocytic leukaemia (ALL) represented 79% and acute non‐lymphocytic leukaemia (ANLL) 16% of the cases, with rates of 43 and 9 per million person–years respectively. There were downward trends in incidence of total leukaemias, ALL and ANLL and ‘not otherwise specified’ (NOS) combined. Incidence of ALL was highest at 1–4 years of age in boys and girls, whereas ANLL peaked in girls during the first year of life. During 1991–96, the decrease in ALL was significant (P = 0.042). A multivariable Poisson regression model identified significant excesses of ALL for boys, for age groups 1–4 and 5–9 years and for three out of seven regions. Possible reasons for the high rates in Costa Rica are discussed.
Socio‐demographic determinants of poor infant outcome in north‐west Russia
Authors: Grjibovski Andrej , Bygren Lars Olov , Svartbo Boo
Published: March 2003

The infant outcome determinants vary in different settings, and there is still a need for analysis within environments. This study was designed to examine the relation between poor infant outcome (PIO), (i.e. any of the following indicators: preterm delivery, low birthweight, perinatal death and low first‐minute Apgar score) and socio‐demographic factors, smoking and alcohol consumption in a Russian setting. The study was conducted in the town of Severodvinsk, north‐west Russia. A total of 1404 pregnant women who attended antenatal care clinics in 1999 and delivered at the municipal maternity home comprised the cohort. Data on women and infants were collected from the medical files and a questionnaire on social indicators, smoking and alcohol consumption was administered. The adjusted odds ratio (OR) calculated by multivariable logistic regression was used as the measure of association between PIO and the variables studied. Education was found to be the most significant factor associated with PIO (OR = 1.9, 95% CI 1.2, 3.0 for secondary or less education compared with at least 3 years of university studies). Increased risks of PIO were also found in mothers aged 30 years and older (OR = 1.6, 95% CI 1.1, 2.5 compared with other age groups) and in unmarried mothers (OR = 1.4, 95% CI 1.0, 1.9) after control for the possible confounders. Other socio‐demographic determinants studied (smoking, alcohol use, stress, maternal occupation, housing and young age of the mother) could not be found to influence PIO. The findings contribute to the hypothesis that maternal education is one of the most important social factors influencing pregnancy outcomes in countries in transition.
Increased mortality in children and adolescents with developmental disabilities
Authors: Decouflé Pierre , Autry Andrew
Published: March 2003

A population‐based cohort of 10‐year‐old children with mental retardation, cerebral palsy, epilepsy, hearing impairment or vision impairment, who were ascertained at 10 years of age in a previous study conducted in metro Atlanta during 1985–87, was followed up for mortality and cause of death information. We used the National Death Index to identify all deaths among cohort members during the follow‐up period (1985–95). We estimated expected numbers of deaths on the basis of actual age‐, race‐ and sex‐specific death rates for the entire Georgia population for 1989–91. The objective was to quantify the magnitude of increased mortality and evaluate the contribution of specific disabilities to mortality among children and adolescents with one or more of five developmental disabilities.

A total of 30 deaths were observed; 10.1 deaths were expected, yielding an observed‐to‐expected mortality ratio of almost three to one. The numbers of observed deaths exceeded those of expected deaths, regardless of the number of disabilities present, but the ratios were statistically significant (at the 95% confidence level) only in children with three or more co‐existing disabilities. In general, the magnitude of the mortality ratios was directly related to various measures of the severity of the person's disability. An exception to this pattern was the elevated mortality from cardiovascular disease among cohort members with isolated mental retardation (three observed deaths vs. 0.2 expected). The specific underlying causes of death among other deceased cohort members included some that were the putative cause of the developmental disability (e.g. a genetic syndrome) and others that could be considered intercurrent diseases or secondary health conditions (e.g. asthma). Prevention efforts to decrease mortality in adolescents and young adults with developmental disabilities may need to address serious conditions that are secondary to the underlying disability (i.e. infections, asthma, seizures) rather than towards injuries, accidents and poisonings, the primary causes of death for persons in this age group in the general population.
Immune responses to third stage larvae of Onchocerca volvulus in interferon‐gamma and interleukin‐4 knockout mice
Authors: JOHNSON EUGENE H. , SCHYNDER‐CANDRIAN SYLVIA , RAJAN THIRUCHANDURAI V. , NELSON F.KENNETH , LUSTIGMAN SARA , ABRAHAM DAVID
Published: March 2003

To shed clarity on the dichotomy of reported results relative to the significance of T helper‐1 vs T helper‐2 immune responses in onchocerciasis, we compared the survivability of Onchocerca volvulus third‐stage larvae (L3) in immunized mice that had either a targeted disruption of the Interleukin‐4 or Interferon‐gamma gene. Treatment groups consisted of control mice and mice immunized with irradiated O. volvulus L3. All mice were challenged with diffusion chambers containing viable L3. Vaccinated IL‐4−/− were unable to kill this larval target. In contrast, vaccinated IFN‐γ−/− and C57BL/6 mice, exhibited high levels of killing, had elevated levels of IL‐4 and significantly greater numbers of eosinophils in their diffusion chambers than the IL‐4−/−. Whereas, levels of IFN‐γ in all three groups of immunized mice were equivalent to those of control mice, levels of IL‐5 were elevated, even in the IL‐4−/−, indicating that cytokines other than IL‐4 were involved in its production. The protective immune response to third‐stage larvae of O. volvulus in mice vaccinated with irradiated larvae has an absolute IL‐4 requirement.
Profound suppression of cellular proliferation mediated by the secretions of nematodes
Authors: ALLEN JUDITH E. , MACDONALD ANDREW S.
Published: March 2003

Loss of T lymphocyte proliferation and the emergence of a host response that is dominated by a Th2‐type profile are well‐established features of human filarial infection. Downregulation and modulation of host T cell responses during lymphatic filariasis has been investigated by implantation of parasite stages into inbred mice. Adherent peritoneal exudate cells (PEC) from mice transplanted with adult or larval Brugia malayi parasites are profoundly anti‐proliferative but do not prevent antigen‐specific cytokine production by T cells. We demonstrate here that the excretory/secretory (E/S) products of the adult parasite are sufficient to induce PEC that block proliferation if injected daily into mice. We have previously shown that in vivo production of host IL‐4 is required for the generation of suppressive cells. Because the induction of host IL‐4 is characteristic of infection with nematodes, we asked whether E/S from two other nematode parasites, Nippostrongylus braziliensis and Toxocara canis were also capable of generating a suppressor cell population. Injection of E/S from these two parasites also led to a reduction in T cell proliferation suggesting that this mechanism of down‐regulating host responses is a feature common to nematode parasites.
Cross reacting antibodies against keyhole limpet haemocyanin may interfere with the diagnostics of acute schistosomiasis
Authors: THORS CECILIA , LINDER EWERT
Published: March 2003

The number of individuals catching schistosomiasis has increased with the popularity of ‘primitive tourism’ in Africa. Highly immunogenic material originating from the intestine of intravascular adult schistosomes gives rise to an antibody response making possible early identification of infected individuals using serology. Antibodies against gut associated antigens (anti‐GAA), detected by indirect immunofluorescence microscopy employing sections of adult worms as antigen may occur before the onset of egg production. In the present study we show that this well known schistosomiasis‐specific anti‐GAA staining reaction can be confused with a similar staining reaction with ducts of both male and female worms. Antibodies with duct reactivity were seen in sera both from schistosomiasis‐patients and patients with some other invasive worm infections. Cross reactive anti‐duct antibodies appear to have different specificity. One cross reactive antibody reacted with antigenic epitopes present in keyhole limpet haemocyanin (KLH). Anti‐duct reactivity could be inhibited by absorption with KLH. This was most obvious in the trichinellosis patient sera.
Mast cells, eosinophils and antibody‐mediated cellular cytotoxicity are not critical in resistance to Trichuris muris
Authors: BETTS CATHERINE J. , ELSE KATHRYN J.
Published: March 2003

The murine intestinal nematode Trichuris muris provides an invaluable model of human infection with T. trichiura. Hence, analysis of the immunological responses in the mouse may elucidate the mechanisms of immunity to trichuriasis in man. The work described here investigates the roles of eosinophils, mast cells and antibody‐dependent cell‐mediated cytotoxicity (ADCC) in the elimination of T. muris from the host gut. Following ablation of IL‐5, and hence eosinophilia, mice usually resistant to T. muris infection remained so. Further, blocking the stem cell factor receptor, c‐kit, to facilitate complete ablation of mast cells over the period of parasite expulsion in resistant mice had no effect on the development of protective immunity. Therefore it can be deduced that eosinophils and mast cells are not critical in resistance. In addition to these studies, the role of antibody‐mediated cellular cytotoxic mechanisms was investigated via the analysis of an infection time course in FcγR−/− mice. These animals, on a resistant background, were fully immune and expelled the parasites before development of the adult stage. Thus this model provides evidence against a major role for ADCC in resistance to infection with T. muris. The studies described here have eliminated some of the major effector mechanisms traditionally associated with helminth infection, and work continues to elucidate the critical immune responses associated with resistance.
Indomethacin treatment slows disease progression and enhances a Th1 response in susceptible BALB/c mice infected with Leishmania major
Authors: DE FREITAS LUIZ A.R. , LAMINE MBOW  , ESTAY MONICA , BLEYENBERG JULIE A. , TITUS RICHARD G.
Published: March 2003

Prostaglandins of the E series inhibit the development of Th1 responses. When infected with Leishmania major, BALB/c mice fail to develop a Th1 response, but instead mount a Th2 response and die of the disease. Therefore, we treated L. major‐infected BALB/c mice with indomethacin, which inhibits prostaglandin production. Indomethacin lessened disease severity (parasite burden and pathology), and promoted a Th1 response, but the mice still succumbed to infection. The explanation for these observations may be two‐fold: (1) the beneficial effects of indomethacin were predominantly observed later in infection (beyond two weeks), a time at which indomethacin was unable to sufficiently block the development of a Th2 response; (2) indomethacin was unable to induce a Th1 response in BALB/c mice that was of the same magnitude as the Th1 response observed in C57BL/6 mice infected with L. major.
Immunization with an affinity purified protein extract from the adult parasite protects lambs against infection with Haemonchus contortus
Authors: KNOX  , SMITH  , SMITH
Published: March 2003

Young lambs were immunized with membrane protein extracts from adult Haemonchus contortus which had been enriched for cysteine protease activity using Thiol‐Sepharose chromatography. The resulting extract comprised several peptides including cysteine as well as serine and metallo‐protease activities although the former predominated. A limited number of the peptide components were glycosylated. Following a single challenge infection with the same parasite, vaccinated lambs had substantially reduced faecal egg outputs and final worm burdens (overall means of 77% and 47%, respectively, from three trials) compared with challenge controls. Antibody in sera from vaccinated lambs was almost exclusively bound to the surface of the parasite gut indicating that protection may be mediated by the inhibition of parasite digestion.
Experimental Leishmania major infection in mice: role of IL‐10
Authors: CHATELAIN RENÉ , MAUZE SMITA , COFFMAN ROBERT L.
Published: March 2003

L. major infection of mice induces polarized Th1 and Th2 responses that are correlated with healing of the infection (Th1) or a fatal disease (Th2). The Th subset specific cytokines, IFNγ and IL‐4, themselves were shown to be important factors for the differentiation into the Th1 and Th2 pathways during infection. We studied the role of the Th2 cytokine IL‐10 during leishmania infection: removal of endogenous IL‐10 by anti‐IL‐10 treatment did not alter the Th2 cytokine pattern in non‐healer mice nor did it modulate DTH reactivity, IgE production or fatal disease progression, but partially blocked the IFNγ inhibiting effect of rIL‐4 in healer mice. During chronic infection similar amounts of IL‐10 were produced in both healer and non‐healer mice. However, at early time‐points during infection IL‐10 production was significantly higher in the non‐healer Th2 responder animals. IL‐10 production in vitro caused significant inhibition of in vitro IFNγ production. In conclusion IL‐10, unlike IL‐4 and IFNγ, does not seem to play a readily detectable role in the Th subset differentiation during L. major infection. However, the high production of IL‐10 early during infection in non‐healer mice and inhibition of leishmania–specific IFNγ production may contribute to drive the immune response towards a Th2 response.
Interleukin‐15 enhances host protection against acute Toxoplasma gondii infection in T‐cell receptor α−/−deficient mice
Authors: LEE YOUNG‐HA , ELY KENNETH H. , LEPAGE ANNE , KASPER LLOYD H.
Published: March 2003

A potential role for T‐cell receptor (TCR)‐γδ cells in response to Toxoplasma gondii has been described. This study was undertaken to evaluate whether exogenous rIL‐15 can enhance the production of γδ T cells in response to infection with T. gondii. For this, C57BL/6 and TCR α‐gene deficient mice (α−/−) were vaccinated with Toxoplasma lysate antigen (TLA) in combination with interleukin (IL)‐15. The cellular and humoral immune response was assessed following immunization. Administration of IL‐15/TLA to α−/−mice lengthened survival time post lethal challenge. Several immunological parameters were increased in the α−/−mice following immunization with IL‐15/TLA including serum immunoglobulin (Ig)G1 and IgG2a antibody titres and splenocyte lymphoproliferation in response to parasite antigen. Further, the CTL response to parasite infected target cells as well as the production of interferon γ was enhanced by IL‐15/TLA administration in the α−/−mice. These observations indicate that the γδ T cells response to this parasite can be enhanced by the administration of exogenous IL‐15 in the presence of parasite lysate antigen.
Cytoadherence of Plasmodium falciparum‐infected erythrocytes in the human placenta
Authors: Maubert Bertrand , Fievet Nadine , Tami Germaine , Boudin Christian , Deloron Philippe
Published: March 2003

In Plasmodium falciparum‐parasitized pregnant women, erythrocytes infected by mature stages of the parasite sequester into placental intervillous spaces. The presence of parasites in the placenta causes maternal anaemia and low birth weight of the infant. In‐vitro studies suggest placental sequestration may involve the cytoadherence of infected erythrocytes to chondroitin sulphate A (CSA) and/or intercellular adhesion molecule 1 (ICAM‐1) expressed by human placental syncytiotrophoblast. We identified P. falciparum receptors expressed on the surface of human syncytiotrophoblast using immunofluorescence of placental biopsies from Cameroon, a malaria‐endemic area. In all placentas, a strongly positive staining was observed on the syncytiotrophoblast for CSA, but not for ICAM‐1, vascular endothelium cell adhesion molecule‐1, E‐selectin, nor CD36. The cytoadherence ability of parasites from pregnant women and nonpregnant subjects was assessed on in‐vitro cultured syncytiotrophoblast. Parasites from pregnant women bound to the trophoblast via CSA but not ICAM‐1. Parasites from nonpregnant hosts either did not bind to the trophoblast culture or bound using ICAM‐1. Our data support the idea that placental sequestration may result from cytoadherence to placental trophoblast and that pregnant women are parasitized by parasites that differ from parasites derived from nonpregnant host by their cytoadherence ability.
Potentiation of vesicular stomatitis New Jersey virus infection in mice by mosquito saliva
Authors: Limesand  , Higgs  , Pearson  , Beaty
Published: March 2003

Saliva of arthropod vectors can modulate vertebrate host immunological functions in many ways. To investigate if vesicular stomatitis New Jersey virus (VSNJ) infection could be potentiated by arthropod saliva, mice in three different age groups (3 days, 3 weeks, or > 8 months) were exposed to VSNJ‐infected mosquitoes or were needle injected with an equivalent dose of VSNJ (titre 1.5–3 logs). Previous studies have demonstrated that VS viruses do not replicate in mice older than 3 weeks of age. Infection was monitored by examining serum for the presence of VSNJ at 2 days postinfection (PI) or for neutralizing antibody on days 7 and 14 PI. All 3‐day‐old mice succumbed to viral infection by mosquito transmission or delivery by injection. Ninety‐four percent of the 3‐week‐old mice bitten by infected mosquitoes developed antibody, whereas antibody was detected in only 13% of inoculated mice. Adult mice developed neutralizing antibody (73%) when fed upon by infected mosquitoes, but only 11% developed antibody when virus was injected. Day 2 serum samples from 3‐week and adult age groups were negative by virus isolation. These data indicate that mosquito mediated delivery of VSNJ exacerbates virus infection in mice older than 3 weeks.
Immunity to experimental neosporosis in pregnant sheep
Authors: Buxton D. , Wright S. , Maley S.W. , Rae A.G. , Lundén A. , Innes E.A.
Published: March 2003

Neospora caninum is an important cause of fetal loss in cattle but has also infrequently been shown to cause disease in sheep and goats. Experimental infection of pregnant sheep with N. caninum causes clinical and pathological changes very similar to those of neosporosis in cattle. An experiment in sheep was undertaken to examine whether infection with N. caninum before pregnancy conferred immunity to subsequent challenge with the parasite during pregnancy. Primary inoculation of NC1 tachyzoites subcutaneously, either before or during pregnancy, caused a significant temperature response in ewes, while those given a secondary challenge at 90 days gestation (dg) did not show such a response. Primary infection of 12 ewes during pregnancy resulted in the loss of all fetuses while a further 12 ewes inoculated with NC1 tachyzoites before mating and subsequently challenged with the same dose at 90 dg produced nine live and seven dead lambs. There were no fetal deaths in ewes only infected with Neospora before mating although there was serological evidence of vertical transmission in four of their clinically normal offspring while Neospora DNA was detected in the cerebrospinal fluid of a fifth healthy lamb. Thus an experimental primary infection with N. caninum during pregnancy killed all the fetuses while inoculation before pregnancy did not cause any mortality but did provide a degree of protection against subsequent challenge with Neospora during pregnancy.
Immune responses to multiple antigen peptides containing T and B epitopes from Plasmodium falciparum circumsporozoite protein of Brazilian individuals naturally exposed to malaria
Authors: Avila Sandra L.M. , Goldberg Anna Carla , Arruk Viviana G. , Marin Maria Lúcia , Guilherme Luiza , Kalil Jorge , Ferreira Antonio Walter
Published: March 2003

We have evaluated the immune responses of individuals living in a malaria endemic area of Brazil to the (T1B)4, a multiple antigen peptide (MAP) from Plasmodium falciparum circumsporozoite (CS) protein and the related monoepitope MAPs, B4 and (T1)4, and the linear peptides, T1B and B. The highest antibody frequencies were against MAPs containing the B cell epitope sequence (T1B)4 (42·2%) and B4 (28·8%), while the highest lymphoproliferative response frequencies were against the MAPs containing the T cell epitope sequence (T1)4 (47%) and (T1B)4 (36·4%). We analysed individual responses considering lymphoproliferative response to (T1)4 MAP and IgG antibody titre to (T1B)4 as patterns of ideal cellular and humoral responses, respectively. The frequency of responders, cellular and/or humoral was 66·6%, significantly higher than non responders (P = 0·003). We also determined the HLA class II haplotype of each individual but no association between these and immune response patterns to the MAPs was observed. The results showed that individuals primed against P. falciparum in their natural habitat, present a very diverse array of responses against the same peptide antigens, varying from no response in one‐third of the individuals to cognate B and T cell responses. Our study underlines the importance of previous studies of vaccine candidates to guarantee that the immunization will be capable of reverting inefficient or absent responses to malaria epitopes.
Susceptibility of the different developmental stages of the asexual (schizogonic) erythrocyte cycle of Plasmodium chabaudi chabaudi to hyperimmune serum, immunoglobulin (Ig)G1, IgG2a and F(ab′)2 fragments
Authors: Cavinato Regiane A. , Bastos Karina R.B. , Sardinha Luiz R. , Elias Rosa M. , Alvarez José M. , D'Império Lima Maria Regina
Published: March 2003

The mechanisms by which antibodies interfere with Plasmodium growth are still under debate. Characterizing the asexual erythrocyte stages susceptible to antibodies from hyperimmune individuals is therefore a relevant contribution to vaccine research. In this study, using a virulent and synchronous murine malaria parasite, Plasmodium chabaudi chabaudi AJ, we have shown that trophozoites and circulating schizonts are not the main targets for antibodies from hyperimmune serum. In drug‐cured mice challenged with a high inoculum of ring‐infected erythrocytes, parasitemias do not decline until the moment of erythrocyte rupture, suggesting that effector mechanisms operate immediately prior to reinvasion. Confirming these findings, treatment of primary‐infected mice with hyperimmune serum inhibited the generation of new ring forms, but did not alter the numbers of schizont‐infected erythrocytes, despite the fact that these cells were recognized by immunoglobulin (Ig)G antibodies. When these mice were treated with IgG1 or IgG2a purified from hyperimmune serum, both subclasses limited reinvasion, but IgG2a showed a stronger protective activity. The fact that Fc digestion decreases but does not abrogate protection suggests that both Fc‐dependent and independent mechanisms participate in this process. Treatment with cobra venom factor did not interfere with the antibody‐mediated protection, ruling out the participation of the complement system in both lysis and phagocytosis of merozoites or infected erythrocytes. Therefore, in mice suffering from P. c. chabaudi AJ malaria, merozoite neutralization seems to be a major mechanism of protection conferred by hyperimmune serum antibodies. However, FcγR‐mediated interactions, or other mechanisms not yet defined, may also contribute to inhibit erythrocyte reinvasion.
Worms and malaria: noisy nuisances and silent benefits
Authors: Nacher Mathieu
Published: March 2003

The burden of malaria mortality has been a major evolutionary influence on human immunity. The selection of the most successful immune responses against malaria has been in populations concomitantly infected by intestinal helminths. Animal models have shown that coinfections with helminths and protozoa in the same host elicit a range of antagonist and synergistic interactions. Recent findings suggest similar interactions take place between helminths, Plasmodium falciparum and humans. However, as the threat of HIV and tuberculosis becomes a major selective force, what used to be a successful ecological system may now prove detrimental. Nevertheless, the understanding of the ecological forces at play may expose new intervention targets for malaria control, and give a new perspective on our shortcomings against the deadliest of human parasites.
Electroantennogram studies of potential oviposition attractants for Toxorhynchites moctezuma and T. amboinensis mosquitoes
Authors: COLLINS LARISSA E. , BLACKWELL ALISON
Published: March 2003

Abstract.Ether extracts of water samples taken from tyre sections in the field were shown to be active in electroantennogram studies with female Toxorhynchites moctezuma (Dyar & Knab) and Toxorhynchites amboinensis (Doleschall). In addition, electroantennograms were recorded from both Toxorhynchites species for seven compounds found commonly in water containing decaying leaves and known to be oviposition attractants for other mosquito species. The compounds were 4‐methylcyclohexanol, phenol, indole, 3‐methylindole, m‐cresol, o‐cresol and p‐cresol. The response thresholds for these compounds ranged between 1 × 10–4μg and 1 μg for female antennae (100 μg for male antennae). These results provide a basis for behavioural studies of oviposition attractants for the Toxorhynchites species.
Age‐grading adult insects: a review of techniques
Authors: Hayes Eleanor J. , Wall Richard
Published: March 2003

Abstract.The range of techniques available for age‐grading adult insects is reviewed, with particular emphasis on species of medical and veterinary importance. Chronological and physiological age‐grading are discussed, considering the relative merits of each approach. The techniques described include those based on changes to the reproductive system, those relying on somatic changes and those dependent on cuticular degradation. The advantages and problems of each technique and the use of a number of techniques in combination are discussed.
The role of pre‐ and post‐imaginal experience in the host‐finding and oviposition behaviour of the cabbage moth
Authors: Rojas Julio C. , Wyatt Tristram D.
Published: March 2003

The influence of pre‐ and post‐imaginal experience on the orientation, landing, and oviposition of the female cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae) was studied in a wind tunnel. The results of experiments on the influence of pre‐imaginal experience do not support the Hopkins host selection hypothesis because the females’ responses to host plants were not affected by the plant species used for feeding the larvae. The females were initially attracted to and landed on chrysanthemum whether or not they were fed on this plant species. In addition, the oviposition preference for cabbage plants was not changed by the larval feeding regimen. Imaginal experience influenced the females’ subsequent orientation/landing responses: exposure of the females to chrysanthemum plants for 5 min decreased their subsequent responses to this species, but subsequent responses to cabbage were not changed when the females were exposed to cabbage plants. Overnight exposure of females to a chrysanthemum or cabbage plant decreased the subsequent orientation/landing on the same species offered in non‐choice tests. A similar effect was observed in responses to chrysanthemum plants after overnight contact, and possibly to cabbage plants, in the two‐choice tests. Overnight exposure to cabbage or chrysanthemum had no effect on subsequent oviposition: females from both treatments oviposited more often on cabbage.
Changes in desiccation resistance during development in the millipedePolydesmus angustus
Authors: David J. ‐F. , Vannier G.
Published: March 2003

Water loss at increasing temperature in dry air (< 5% r.h.) was measured for the eight stadia ofPolydesmus angustusLatzel (Diplopoda, Polydesmida: Polydesmidae). Instantaneous rates of water loss, expressed as percentages of original body water, were calculated at 20, 25 and 30°C. At each temperature, the rate of water loss varied greatly among stadia, decreasing between 15‐ and 18‐fold from stadium I to stadium VII, and then significantly increasing from stadium VII to stadium VIII (adult). In all stadia, the rate of water loss increased with rising temperature, but the temperature effect was much more pronounced in juveniles than in larger stadia. The threshold temperature of heat stupor, which was measured from stadium IV onwards, increased significantly during development, from 35.6°C in stadium IV to 39.5°C in adults. Survival at 20°C and 76% r.h. varied as could be expected from the water loss rates in dry air, survival time increasing from stadium I to stadium VII and then decreasing from stadium VII to the adult stage. The maximum tolerable water loss, estimated for stadia V, VII and adults, did not change significantly among stadia (mean: 47% of the original water content), suggesting that survival times under desiccating conditions depended primarily on the rates of water loss. The relevance of the results in terms of summer survival under natural conditions is discussed, and it is concluded that juvenile mortality could be substantial in the field. This is important for understanding the adaptive value of cohort‐splitting inP. angustus.
The effect of relative humidity on the behaviour and development of Triatoma brasiliensis
Authors: Guarneri Alessandra A. , Lazzari Claudio , Diotaiuti Liléia , Lorenzo Marcelo G.
Published: March 2003

Abstract The preference for relative humidity (RH) and suitability of different levels of this environmental parameter were investigated in the haematophagous bug Triatoma brasiliensis Neiva, 1911 (Hemiptera, Reduviidae). The hygropreference of T. brasiliensis was studied using a RH gradient and the effect of different RHs on the egg hatching, nymph mortality and moulting success was also analysed. The results show that egg hatching in first‐instar nymphs of T. brasiliensis was lower at extreme RHs and, particularly, it was lowest at 9.3% RH. The survival of starved nymphs was not affected by RH, but the percentage of engorged nymphs and the ecdysis success of these nymphs once fed was diminished strongly by high humidity. Fourth‐instar nymphs preferred to stay at the lowest RH during the first 5 days after feeding and during ecdysis. This preference changed markedly during starvation. Fifteen days after ecdysis, the bugs moved towards intermediate humidities, and 30 days after ecdysis they even preferred the most humid sectors of the gradient. Females preferred to lay eggs in dry environments, suggesting that they may not have a particular hygropreference for oviposition, but that they simply lay their eggs at the RHs where they prefer to stay.
Nutritional suitability of individual carbohydrates and amino acids for adult Pieris brassicae
Authors: Romeis J. , Wäckers F. L.
Published: March 2003

Abstract Many adult Lepidoptera are dependent on carbohydrate‐rich solutions such as nectar and honeydew. These food sources can contain a range of carbohydrates as well as low levels of other compounds, including free amino acids, proteins and lipids. Little is known about the nutritional value of individual nectar sugars and amino acids for adult Lepidoptera. Ten sugars occurring in nectar and honeydew were tested with respect to their effects on a number of Pieris brassicae life‐table parameters. In similar experiments it was investigated whether the butterfly derives nutritional benefits from mixtures of common non‐essential or essential amino acids when provided either in water or in a sucrose solution. Food sources were found to have a significant effect on butterfly fertility, longevity, lifetime fecundity and daily oviposition rate. Whereas a number of sugars significantly increase longevity, melibiose and melezitose reduce P. brassicae longevity. Butterfly fecundity is compromized significantly by sucrose and melibiose. Glucose is the only sugar that has a positive effect on both longevity and fecundity as well as a number of oviposition parameters. Amino acids seem to have no or only a minor effect on the life‐table parameters tested. However, when provided in sucrose, they appear to compensate for the negative effect of pure sucrose on fecundity. A comparison with an earlier study on the gustatory response of P. brassicae shows that there is only a weak correlation between the nutritional value of sugars and amino acid mixtures and their perceptibility.
Sucrose metabolism in cold‐stored potato tubers with decreased expression of sucrose phosphate synthase
Authors: Krause K.‐P. , Hill L. , Reimholz R. , Hamborg Nielsen T. , Sonnewald U. , Stitt M.
Published: March 2003

Transfer of potato tubers to low temperature leads after 2–4 d to a stimulation of sucrose synthesis, a decline of hexose‐phosphates and a change in the kinetic properties, and the appearance of a new form of sucrose phosphate synthase (SPS). Antisense and co‐suppression transformants with a 70–80% reduction in SPS expression have been used to analyse the contribution of SPS to the control of cold sweetening. The rate of sucrose synthesis in cold‐stored tubers was investigated by measuring the accumulation of sugars, by injecting labelled glucose of high specific activity into intact tubers, and by providing 50 mol m–3 labelled glucose to fresh tuber slices from cold‐stored tubers. A 70–80% decrease of SPS expression resulted in a reproducible but non‐proportional (10–40%) decrease of soluble sugars in cold‐stored tubers, and a non‐proportional (about 25%) inhibition of label incorporation into sucrose, increased labelling of respiratory intermediates and carbon dioxide, and increased labelling of glucans. The maximum activity of SPS is 50‐fold higher than the net rate of sugar accumulation in wild‐type tubers, and decreased expression of SPS in the transformants was partly compensated for increased levels of hexose‐phosphates. It is concluded that SPS expression per se does not control sugar synthesis. Rather, a comparison of the in vitro properties of SPS with the estimated in vivo concentrations of effectors shows that SPS is strongly substrate limited in vivo. Alterations in the kinetic properties of SPS, such as occur in response to low temperature, will provide a more effective way to stimulate sucrose synthesis than changes of SPS expression.
Stem water storage and diurnal patterns of water use in tropical forest canopy trees
Authors: Goldstein G. , Andrade J. L. , Meinzer F. C. , Holbrook N. M. , Cavelier J. , Jackson P. , Celis A.
Published: March 2003

Stem water storage capacity and diurnal patterns of water use were studied in five canopy trees of a seasonal tropical forest in Panama. Sap flow was measured simultaneously at the top and at the base of each tree using constant energy input thermal probes inserted in the sapwood. The daily stem storage capacity was calculated by comparing the diurnal patterns of basal and crown sap flow. The amount of water withdrawn from storage and subsequently replaced daily ranged from 4 kg d–1 in a 0·20‐m‐diameter individual of Cecropia longipes to 54 kg d–1 in a 1·02‐m‐diameter individual of Anacardium excelsum, representing 9–15% of the total daily water loss, respectively. Ficus insipida, Luehea seemannii and Spondias mombin had intermediate diurnal water storage capacities. Trees with greater storage capacity maintained maximum rates of transpiration for a substantially longer fraction of the day than trees with smaller water storage capacity. All five trees conformed to a common linear relationship between diurnal storage capacity and basal sapwood area, suggesting that this relationship was species‐independent and size‐specific for trees at the study site. According to this relationship there was an increment of 10 kg of diurnal water storage capacity for every 0·1 m2 increase in basal sapwood area. The diurnal withdrawal of water from, and refill of, internal stores was a dynamic process, tightly coupled to fluctuations in environmental conditions. The variations in basal and crown sap flow were more synchronized after 1100 h when internal reserves were mostly depleted. Stem water storage may partially compensate for increases in axial hydraulic resistance with tree size and thus play an important role in regulating the water status of leaves exposed to the large diurnal variations in evaporative demand that occur in the upper canopy of seasonal lowland tropical forests.
Effects of exposure to humid air on epidermal viability and suberin deposition in maize (Zea mays L.) roots
Authors: Enstone D. E. , Peterson C. A.
Published: March 2003

When the basal zones of 4‐d‐old hydroponically grown maize (Zea mays L. cv. Seneca Horizon) roots were exposed to moist air for 2 d, the development of both endodermis and exodermis was affected. In the endodermis, Casparian bands enlarged and more cells developed suberin lamellae. The most striking effect was seen in the exodermis. In submerged controls, only 4% of the cells had Casparian bands, whereas in root regions exposed to air, 93% developed these structures. Similarly, in submerged roots 11% of the exodermal cells had either developing or mature suberin lamellae compared with 92% in the air‐treated region. The majority of epidermal cells remained alive in the zone exposed to air. Some cell death had occurred earlier in the experiment when the seedlings were transferred from vermiculite to hydroponic culture. The precise stimulus(i) associated with the air treatment which led to accelerated development in both endodermis and exodermis is as yet unknown.
Determination of cell water‐relation parameters using the pressure probe: extended theory and practice of the pressure‐clamp technique
Authors: Murphy R. , Smith J. A. C.
Published: March 2003

The aim of the present study was to develop and test an extended theory of the pressure‐clamp technique that would allow the estimation of additional cell water‐relation parameters using the pressure probe. It was assumed that intercellular water transport (vacuole → vacuole) occurs via a composite ‘membrane’ comprising the tonoplast, cytoplasm, plasma membrane, plasmodesmata and cell wall and that solute transport across the micropipette tip of the probe is dominated by convection. The extended theory allows the simultaneous estimation of cell volume (V), effective cell‐sap osmotic pressure (σΠ0), composite‐membrane hydraulic conductance (ALP) and the ‘instantaneous’ volume change (v0) at the start of the pressure clamp. With an estimate of cell‐sap osmotic pressure (Π0), the weighted‐average reflection coefficient (σ) of the composite membrane may also be determined from an endosmotic pressure‐clamp experiment. In principle, the cell volume before the clamp (V0) can be estimated as V0 = V + v0, and the cell volumetric elastic modulus (ɛ) can be estimated as ɛ = –V0(ΔP/v0), where ΔP (< 0) is the change in turgor pressure at t = 0. In practice it may be necessary to correct v0 for transmembrane water flow when estimating V0 and ɛ. To test this theory, a previously described pressure‐probe system was upgraded by incorporating a data‐acquisition system to record turgor pressure, meniscus position, the penetration depth of the pressure‐probe micropipette and the micropipette profile. An air bubble in the system allowed the turgor pressure to be clamped at a near‐constant value. For mesophyll cells in leaf discs of Kalanchoë daigremontiana, the estimated mean value of V0[(2·46 ± 0·24) × 10–13 m3] was in reasonable agreement with a value obtained from microscopy [(1·91 ± 0·10) × 10–13 m3]. When the positive correlation between ɛ and |ΔP| was taken into account, the parameter estimates obtained from pressure‐clamp experiments were found to be consistent with those derived from pressure‐relaxation experiments. The mean values of ɛ (1·4 ± 0·2 MPa) and LP[(5·76 ± 0·83) × 10–12 m s–1 Pa–1] were significantly different from previous estimates obtained with older leaves. Furthermore, in contrast to the estimated reflection coefficient of the plasma membrane/tonoplast (≈ 1), the mean value of σ obtained in the present study (0·62 ± 0·05) was significantly less than unity. This is attributed to a high hydraulic conductance and a low reflection coefficient of a symplastic pathway for intercellular water transport. The qualitative behaviour of LP and σ was consistent with a quasi‐steady‐state model of intercellular water transport that included volume flow through plasmodesmata. A quantitative description was obtained by fitting a simplified version of this model to the data. This led to the conclusion that significant volume flow can occur through plasmodesmata during pressure‐clamp experiments, especially for small A and |ΔP|.
Response of sugar beet (Beta vulgaris L.) yield and biochemical composition to elevated CO2 and temperature at two nitrogen applications
Authors: Demmers‐Derks H. , Mitchell R. A. C. , Mitchell V. J. , Lawlor D. W.
Published: March 2003

Effects on sugar beet (Beta vulgaris L.) of current and elevated CO2 and temperature alone and in combination and their interactions with abundant and deficient nitrogen supply (HN and LN, respectively) have been studied in three experiments in 1993, 1994 and 1995. Averaged over all experiments, elevated CO2 (600 μmol mol–1 in 1993 and 700 μmol mol–1 in 1994 and 1995) increased total dry mass at final harvest by 21% (95% confidence interval (CI) = 21, 22) and 11% (CI = 6, 15) and root dry mass by 26% (CI = 19, 32) and 12% (CI = 6, 18) for HN and LN plants, respectively. Warmer temperature decreased total dry mass by 11% (CI = – 15, – 7) and 9% (CI = – 15, – 5) and root dry mass by 7% (CI = – 12, – 2) and 7% (CI = – 10, 0) for HN and LN plants, respectively. There was no significant interaction between temperature and CO2 on total or root dry mass. Neither elevated CO2 nor temperature significantly affected sucrose concentration per unit root dry mass. Concentrations of glycinebetaine and of amino acids, measured as α‐amino‐N, decreased in elevated CO2 in both N applications; glycinebetaine by 13% (CI = – 21, – 5) and 16% (CI = – 24, – 8) and α‐amino‐N by 24% (CI = – 36, – 11) and 16% (CI = – 26, – 5) for HN and LN, respectively. Warmer temperature increased α‐amino‐N, by 76% (CI = 50, 107) for HN and 21% (CI = 7, 36) for LN plants, but not glycinebetaine.