Dissociative photoionization of NO across a shape resonance in the XUV range using circularly polarized synchrotron radiation

We report benchmark results for dissociative photoionization (DPI) spectroscopy and dynamics of the NO molecule in the region of the σ^* shape resonance in the ionization leading to the NO⁺(c³Π) ionic state. The experimental study combines well characterized extreme ultraviolet (XUV) circularly polarized synchrotron radiation, delivered at the DESIRS beamline (SOLEIL), with ion-electron coincidence 3D momentum spectroscopy. The measured (N⁺, e) kinetic energy correlation diagrams reported at four discrete photon energies in the extended 23-33 eV energy range allow for resolving the different active DPI reactions and underline the importance of spectrally resolved studies using synchrotron radiation in the context of time-resolved studies where photoionization is induced by broadband XUV attosecond pulses. In the dominant DPI reaction which leads to the NO⁺(c³Π) ionic state, photoionization dynamics across the σ^* shape resonance are probed by molecular frame photoelectron angular distributions where the parallel and perpendicular transitions are highlighted, as well as the circular dichroism CDAD(θ_e) in the molecular frame. The latter also constitute benchmark references for molecular polarimetry. The measured dynamical parameters are well described by multichannel Schwinger configuration interaction calculations. Similar results are obtained for the DPI spectroscopy of highly excited NO⁺ electronic states populated in the explored XUV photon energy range.

The course of inflammatory bowel disease during pregnancy and postpartum: a prospective European ECCO-EpiCom Study of 209 pregnant women

BACKGROUND

The impact of pregnancy on the course of IBD is still controversial.

AIM

To investigate the impact of pregnancy on IBD and to search for factors with potential impact on remission.

METHODS

Pregnant IBD women from 12 European countries were enrolled between January 2003 and December 2006 and compared at conception (1:1) with nonpregnant IBD women. Data on disease course were prospectively collected at each trimester during pregnancy and in the postpartum (6 months) using a standardised questionnaire.

RESULTS

A total of 209 pregnant IBD women were included: 92 with Crohn's disease (CD; median age 31 years, range 17-40) and 117 with ulcerative colitis (UC; median age 32 years, range 19-42). No statistically significant difference in disease course during pregnancy and postpartum was observed between pregnant and nonpregnant CD women. Longer disease duration in CD and immunosuppressive therapy were found to be risk factors for activity during pregnancy. Pregnant UC women were more likely than nonpregnant UC women to relapse both during pregnancy (RR 2.19; 95% CI: 1.25-3.97, 0.004) and postpartum (RR 6.22; 95% CI: 2.05-79.3, P = 0.0004). During pregnancy, relapse was mainly observed in the first (RR 8.80; 95% CI 2.05-79.3, P < 0.0004) and the second trimester (RR 2.84, 95% CI 1.2-7.45, P = 0.0098).

CONCLUSIONS

Pregnant women with Crohn's disease had a similar disease course both during pregnancy and after delivery as the nonpregnant women. In contrast, pregnant women with ulcerative colitis were at higher risk of relapse during pregnancy and in the postpartum than nonpregnant ulcerative colitis women.

The role of Rydberg states in photoionization of NO2 and (NO+, O-) ion pair formation induced by one VUV photon

We report a combined experimental and theoretical study of photoionization (PI) of the NO2 molecule into the NO2(+) (X (1)Σg(+)) ground state and the photodissociation of NO2 into the NO(+)((1)Σ(+)) + O(-)((2)P) ion pair. These processes were induced by 10.9 eV-13 eV synchrotron radiation and the products were detected using electron-ion or O(-)-NO(+) coincident momentum spectroscopy. The results demonstrate the strong influence of [R(∗)(4b2)(-1), nlα(i), v2(')] Rydberg states vibrationally resolved in the v2(') bending modes for both processes. In particular, we emphasize two regions around 11.5 eV and 12.5 eV that were studied in more detail for their relevance to 400 nm multiphoton ionization induced by femtosecond pulses. The photoelectron energy spectra and asymmetry parameters support the existence of two PI mechanisms, as probed with the help of fixed-nuclei frozen-core Hartree-Fock calculations. We found significant deviations from Franck-Condon ionization predictions which may be assigned to vibronic coupling of NO2(∗) states such as that induced by a conical intersection. The limited agreement between theory and experiment, even for the non-resonant processes, indicates the need for calculations that go beyond the approximations used in the current study. Ion pair formation leads to strong vibrational and rotational excitation of the NO(+)((1)Σ(+),v) product, with an ion fragment angular anisotropy depending on both the v2(') bending quantum number of the excited parent molecule and the v vibrational level of the fragment.

Valence and inner-valence shell dissociative photoionization of CO in the 26-33 eV range. I. Ion-electron kinetic energy correlation and laboratory frame photoemission

The (V(A+), V(e), ê) vector correlation method, combining imaging and time-of-flight resolved electron-ion coincidence techniques, is used to probe dissociative photoionization (DPI) of CO induced by vacuum ultra violet linearly or circularly polarized synchrotron radiation in the 26-33 eV photon excitation energy range. It provides original information about both the photoionization dynamics of the CO molecule and the dissociation dynamics of the CO(+) molecular ions. The explored region corresponds to valence and inner-valence CO(+) ionic states, which involve doubly or multiply excited electronic configurations. In this paper I we identify up to 17 DPI reaction pathways by the position of the intermediate CO(+) molecular states in the Franck-Condon region and the (C(+) + O) or (O(+) + C) dissociation limits to which they correlate. For these processes we report the laboratory frame beta(C+/O+) and beta(e) asymmetry parameters as well as the relative branching ratios in selected binding energy bands. The I(chi,theta(e),phi(e)) molecular frame photoelectron angular distributions for selected PI processes will be reported in a companion paper II and compared with multichannel Schwinger configuration interaction ab initio calculations of these observables.

Molecular frame and recoil frame photoelectron angular distributions from dissociative photoionization of NO2

The authors report measured and computed molecular frame photoelectron angular distributions (MFPADs) and recoil frame photoelectron angular distributions (RFPADs) for the single photon ionization of the nonlinear molecule NO2 leading to the (1a2)-1 b 3A2 and (4a1)-1 3A1 states of NO2+. Experimentally, the RFPADs were obtained using the vector correlation approach applied to the dissociative photoionization (DPI) involving these molecular ionic states. The polar and azimuthal angle dependences of the photoelectron angular distributions are measured relative to the reference frame provided by the ion recoil axis and direction of polarization of the linearly polarized light. Experimental results are reported for the photon excitation energies hnu=14.4 and 22.0 eV. Theoretically the authors give expressions for both the MFPAD and the RFPAD. They show that the functional form in the recoil frame, where an average over the azimuthal dependence of the molecular fragments about the recoil direction is made, is identical to that they have earlier found for the DPI experiments performed on linear molecules. MFPADs were then computed using single-center expansion techniques within the fixed-nuclei frozen-core Hartree-Fock approximation. The computed cross sections for ionization to the (1a2)-1 b 3A2 state show a strong propensity for ionization with the polarization of the light perpendicular to the plane of the molecule, whereas the ionization to the (4a1)-1 3A1 state of the ion is of similar intensity for all orientations of the polarization of the light in the molecular frame. These qualitative features of the MFPAD are also evident in the RFPAD. The RFPAD for ionization leading to the (1a2)-1 b 3A2 state is strongly peaked in the perpendicular orientation, whereas the RFPAD for ionization leading to the (4a2)-1 3A1 state is much more nearly isotropic. Comparison between experimental and theoretical RFPADs indicates that the recoil angle for NO+ fragments is approximately 50 degrees relative to the symmetry axis of the initial C2v symmetry of the NO2 molecule in the ionization leading to the (1a2)-1 b 3A2 state and the recoil angle is approximately 120 degrees for the O+ fragment for ionization leading to the (4a1)-1 3A1 state.

Molecular frame photoelectron emission in the presence of autoionizing resonances

We have measured the angular distribution of valence-shell photoelectrons excited by circularly polarized light from fixed-in-space N2O molecules, near to and on top of resonances due to Rydberg states embedded in the ionization continuum. The sign of the circular dichroism for ionization into the N2O+ (B2Pi, (1pi)-1) state is reversed on top of the lowest dominant resonances. Measured angular distributions are well predicted by state-of-the-art multichannel configuration interaction calculations. The change in sign of the circular dichroism at the peak of the resonance is the result of a rapid change in the phases of resonant dipole matrix elements by a factor of 2pi as the energy is scanned across the resonance.

Dissociative photoionization of N2O in the region of the N2O+(B 2Π) state studied by ion–electron velocity vector correlation

Dissociative direct photoionization of the N2O(X 1Sigma+) linear molecule via the N2O+(B 2Pi) ionic state induced by linearly polarized synchrotron radiation P in the 18-22 eV photon energy range is investigated using the (VA+,Ve,P) vector correlation method, where VA+ is the nascent velocity vector of the NO+, N2+, or O+ ionic fragment and Ve that of the photoelectron. The DPI processes are identified by the ion-electron kinetic energy correlation, and the IchiA+(thetae,phie) molecular frame photoelectron angular distributions (MFPADs) are reported for the dominant reaction leading to NO+ (X 1Sigma+,v) + N(2D)+ e. The measured MFPADs are found in satisfactory agreement with the reported multichannel Schwinger configuration interaction calculations, when bending of the N2O+(B 2Pi) molecular ion prior to dissociation is taken into account. A significant evolution of the electron scattering anisotropies is observed, in particular in the azimuthal dependence of the MFPADs, characteristic of a photoionization transition between a neutral state of Sigma symmetry and an ionic state of Pi symmetry. This interpretation is supported by a simple model describing the photoionization transition by the coherent superposition of two ssigma and ddelta partial waves and the associated Coulomb phases.

Strategy for diagnosis of congenital toxoplasmosis: evaluation of methods comparing mothers and newborns and standard methods for postnatal detection of immunoglobulin G, M, and A antibodies

In a study involving 14 laboratories supported by the European Community Biomed 2 program, we evaluated immunologic methods for the postnatal diagnosis of congenital toxoplasmosis (CT). Among babies born to mothers who seroconverted to positivity for toxoplasmosis during pregnancy, we analyzed 55 babies with CT on the basis of persistent anti-Toxoplasma immunoglobulin G (IgG) at 1 year of life and 50 control babies without anti-Toxoplasma IgG at 1 year of life in the absence of curative treatment with pyrimethamine-sulfonamides. We tested in-house methods such as the enzyme-linked immunofiltration assay (ELIFA) or Immunoblotting (IB) for the detection of IgG or IgM; these methods allowed comparison of the immunologic profiles of the mothers and the infants. We compared ELIFA and IB with a commercial enzyme immunoassay (EIA) or in-house immunosorbent agglutination assay (ISAGA) for the detection of IgM or IgA. The performances of combinations of methods were also assessed. A cumulative sensitivity of 98% during a 1-year follow-up was obtained with the ELIFA plus ISAGA combination. Only one case of CT was missed by the ELIFA plus ISAGA combination, whereas three cases were missed by the IB plus ISAGA combination, even though 48% of patients with CT were treated with pyrimethamine-sulfonamides, which are known to inhibit antibody neosynthesis. A similar performance was obtained with either ELIFA or IB in combination with EIA. The difference in performance between ELIFA plus ISAGA and IB plus ISAGA was not statistically significant (P = 0.31), and we conclude that both combinations of tests can be used for the diagnosis of CT in newborns.

Ecological comparison of the risks of mother-to-child transmission and clinical manifestations of congenital toxoplasmosis according to prenatal treatment protocol

We compared the relative risks of mother-to-child transmission of Toxoplasma gondii and clinical manifestations due to congenital toxoplasmosis associated with intensive prenatal treatment in Lyon and Austria, short term treatment in 51% of Dutch women, and no treatment in Danish women. For each cohort, relative risks were standardized for gestation at seroconversion. In total, 856 mother-child pairs were studied: 549 in Lyon, 133 in Austria, 123 in Denmark and 51 in The Netherlands. The relative risk for mother-to-child transmission compared to Lyon was 1.24 (95% CI: 0.88, 1.59) in Austria; 0.59 (0.41, 0.81) in Denmark; and 0.65 (0.37, 1.01) in The Netherlands. Relative risks for clinical manifestations compared with Lyon (adjusted for follow-up to age 3 years) were: Austria 0.19 (0.04, 0.51); Denmark 0.60 (0.13, 1.08); and The Netherlands 1.46 (0.51, 2.72). There was no clear evidence that the risk of transmission or of clinical manifestations was lowest in centres with the most intensive prenatal treatment.

Vector correlations in dissociative photoionization of diatomic molecules in the VUV range: strong anisotropies in electron emission from spatially oriented NO molecules

Imaging and time-resolved coincidence techniques are combined to determine ion-electron (v-->(i),v-->(e)) velocity correlations in dissociative photoionization of diatomic molecules induced by synchrotron linearly polarized light P-->. The (v-->(i),v-->(e), P-->) vector correlation yields the identification of each process, together with the ( straight theta(e), straight phi(e)) electron emission in the molecule frame for each orientation of the internuclear axis with respect to the polarization. Strong electron emission anisotropies are observed in the NO molecule frame for the parallel and the perpendicular transitions of the NO+hnu(22-25 eV)-->NO+(c(3) Pi)+e-->N+(3P)+O(3P)+e reaction.

Diagnosis of congenital toxoplasmosis in the neonatal period: A multicenter evaluation

OBJECTIVE

To evaluate different laboratory tests used to diagnose congenital toxoplasmosis in the neonatal period.

STUDY DESIGN

A retrospective multicenter study of 294 pregnant women who experienced seroconversion for Toxoplasma gondii and subsequently delivered live-born infants. Fetal infection was assessed via specific IgM and IgA antibodies (cord and neonatal blood) and detection of T gondii in placenta and cord blood by mouse inoculation.

RESULTS

Ninety-three (32%) of the 294 infants were congenitally infected. The sensitivity of IgA in cord blood and in neonatal blood was 64% and 66%; the sensitivity of IgM was 41% and 42%, respectively. Mouse inoculation of the placenta and cord blood had sensitivities of 45% and 16%. Positive results of the serologic tests in congenitally infected children correlated significantly with the gestational age at the time of maternal infection but was not significantly influenced by the administration of specific antiparasitic treatment during pregnancy.

CONCLUSION

Specific T gondii IgA antibody is a more sensitive test than IgM for detecting congenital toxoplasmosis in the neonatal period. The overall specificity is better for serologic tests performed on neonatal blood than for those on cord blood. Neonatal screening with IgM or IgA antibodies will not detect the majority of children with congenital toxoplasmosis when the maternal infection occurred before the 20th week of pregnancy.

Feasibility of neonatal screening for toxoplasma infection in the absence of prenatal treatment. Danish Congenital Toxoplasmosis Study Group

BACKGROUND

The best method for prevention and control of congenital toxoplasma infection is uncertain. Prenatal screening is done in Austria and France, but the effect of treatment during pregnancy is not well documented. The aim of our study was to find out the maternofetal transmission rate and outcome in infants born to mothers who were not treated during pregnancy.

METHODS

We analysed 89873 eluates from phenylketonuria (PKU) cards from neonates and paired first-trimester serum samples from the mothers for specific IgG antibodies to Toxoplasma gondii. Children born to mothers who seroconverted during pregnancy were followed-up clinically and serologically to 12 months of age. In addition, 21144 PKU cards were analysed for toxoplasma-specific IgM antibodies during the last 12 months of the study.

FINDINGS

In 24989 (27.8%) cases both the PKU eluate and the first-trimester samples were IgG positive, which indicates previous maternal infection. 139 of the 64884 seronegative women acquired toxoplasma infection during pregnancy and gave birth to 141 infants (two sets of twins). 27 of these children were diagnosed with congenital toxoplasma infection. The transmission rate was 19.4% (95% CI 13.2-27.0). Clinical signs and symptoms were found in four (15%) of the 27 children. The additional analysis for toxoplasma-specific IgM antibodies from the PKU card identified seven of nine children with congenital toxoplasma infection. The false-positive rate for the IgM test was 0.19 per 1000, and no false-negatives were found.

INTERPRETATION

The risks of transmission of infection and of disease in the infant are low in an area with a low risk of toxoplasma infection. A neonatal screening programme based on detection of toxoplasma-specific IgM antibodies alone will identify between 70% and 80% of cases of congenital toxoplasmosis.

Risk factors for parvovirus B19 infection in pregnancy

CONTEXT

Parvovirus B19 infection during pregnancy has been associated with fetal death. However, the incidence of and risk factors for infection in pregnant women have not been well studied.

OBJECTIVES

To estimate a pregnant woman's risk of infection with parvovirus B19 in epidemic and endemic situations and to study risk factors for infection.

DESIGN

Population-based cohort study conducted between November 1992 and June 1994.

SETTING

Three regions in Denmark.

PARTICIPANTS

A total of 30946 pregnant women from a consecutive and population-based screening.

MAIN OUTCOME MEASURES

Specific IgG antibodies in serum samples obtained in the first trimester of pregnancy and from the newborn infant to assess past infection and seroconversion. Information on family structure, educational background, socioeconomic status, and pregnancy outcome was obtained from national registers.

RESULTS

Based on 30 946 serum samples, 65.0% of pregnant women had evidence of past infection. Annual seroconversion rates among susceptible women during endemic and epidemic periods were 1.5% (95% confidence interval [CI], 0.2%-1.9%) and 13.0% (95% CI, 8.7%-23.1 %), respectively. Baseline seropositivity was significantly correlated with increasing number of siblings, having a sibling of the same age, number of own children, and occupational exposure to children. Risk of acute infection increased with the number of children in the household as follows: 0 children odds ratio (OR), 1 (reference); 1 child OR, 3.17 (95% CI, 2.24-4.49); 2 children OR, 5.47 (95% CI, 3.55-8.45); 3 or more children OR, 7.54 (95% CI, 3.80-14.94). Having children aged 6 to 7 years resulted in the highest rate of seroconversion among mothers (6.8%; OR, 4.07; 95% CI, 1.89-8.73). Compared with other pregnant women, nursery school teachers had a 3-fold increased risk of acute infection (OR, 3.09; 95% CI, 1.62-5.89). Population-attributable risk of seroconversion was 55.4% for number of own children and 6.0% for occupational exposure.

CONCLUSIONS

The risk of infection is high for susceptible pregnant women during epidemics and associated with the level of contact with children. Nursery school teachers have the highest occupational risk, but most infections seem to be the result of exposure to the woman's own children.

Neospora caninum infection and repeated abortions in humans

To determine whether Neospora caninum, a parasite known to cause repeated abortions and stillbirths in cattle, also causes repeated abortions in humans, we retrospectively examined serum samples of 76 women with a history of abortions for evidence of N. caninum infection. No antibodies to the parasite were detected by enzyme-linked immunosorbent assay, immunofluorescence assay, or Western blot.

[Headache, fatigue and edema of the lower limbs during the third trimester of normal pregnancy]

A series of 180 pregnant women with normal pregnancies participated in the study. A questionnaire concerning the presence of headache, fatigue and oedema of the lower limbs was filled out daily from the 30th gestational week to delivery. After the study period 120 questionnaires, of whom eight were excluded, were available for analysis. The weekly prevalences of headache and fatigue during the observation-period were nearly constant with values of 20% and 50%, respectively. The weekly prevalence of oedema increased significantly from 20% in the 31st week to 60% in the 42nd gestational week. Thirty-five percent had not suffered from headache, 22% did not report fatigue, and 42% did not describe oedema at all during the third trimester. The prevalence of headache and fatigue correlated significantly to increasing parity whereas headache was significantly correlated to decreasing age. Headache, fatigue, and oedema are common symptoms in the third trimester of normal pregnancy, and as such their presence alone should not usually give cause for suspicion of disease.

Classification system and case definitions of Toxoplasma gondii infection in immunocompetent pregnant women and their congenitally infected offspring. European Research Network on Congenital Toxoplasmosis

Classification systems and case definitions provide the foundations upon which clinical and epidemiological studies are based. The European Research Network on Congenital Toxoplasmosis acknowledged the lack of such a system or definitions within its field of interest and established a working group to address the issue. Congenital Toxoplasma gondii infection was defined as occurring in four separate patient groups: pregnant women, fetuses, infants, and individuals > 1 year of age. The likelihood of Toxoplasma gondii infection was separated into five mutually exclusive categories: definite, probable, possible, unlikely, and not infected. Inclusion within a specific category is dependent upon the case definition, which is in turn derived from criteria based on serological, parasitological, and clinical information. Notes are included within the classification not only to clarify the definitions, but also to improve the reliability and quality of diagnosis. The goal is to construct a system that encompasses all aspects of congenital toxoplasmosis, which is applicable to different countries and health services, suitable for large epidemiological studies, aids the diagnosis and management of individual cases, and lends itself to computerisation.

[Toxoplasmosis-chorioretinitis: clinical course and treatment of seven patients]

Toxoplasmosis is a major and preventable cause of severe visual loss and blindness in young people. Ocular toxoplasmosis is the leading cause of posterior uveitis and in most cases it represents a late manifestation of a congenital infection. The clinical picture and anti-Toxoplasma therapy of seven patients referred to the Department of Infectious Diseases, Hvidovre Hospital is described. All patients had clinical ocular toxoplasmosis at initial examination with unilateral focal necrotizing retinitis associated with typical old, pigmented scars. All patients had anti-toxoplasmosis IgG antibodies. After anti-Toxoplasma therapy with sulfadiazine, pyrimethamine and corticosteroid the ocular lesions were healed to atrophic scars and the inflammatory activity disappeared. We conclude that when the clinical picture is compatible with toxoplasmosis, antibodies to Toxoplasma gondii are demonstrated and there is no other diagnosis, anti-Toxoplasma treatment should be considered. It is important to inform pregnant women about prophylactic measures, and to perform a serological screening of newborns, since treatment of congenital toxoplasmosis from birth improves the prognosis.

[Occurrence of toxoplasmosis in pregnant women in Denmark. A study of 5.402 pregnant women]

Consecutive serum samples from 5402 women were analyzed for specific IgG and IgM Toxoplasma gondii antibodies by enzyme immunosorbent assay. The prevalence of IgG antibodies was 27.4%. The seroconversion rate was estimated to be 1.16% per year (SE = 0.0017) in all age groups, consistent with an incidence of acute toxoplasmosis in pregnant women of 0.65%. Based on theses figures, the estimated number of congenitally infected cases are discussed. There was no difference in the prevalence of antibodies in women from rural or urban areas, or from different parts of Denmark.

Outcome of children after maternal primary Toxoplasma infection during pregnancy with emphasis on avidity of specific IgG. The Study Group

Congenital toxoplasmosis results from maternal primary infection during pregnancy. In our serologic screening study 42 of 16,733 pregnant women had findings suggestive of primary infection. Here we document the outcome of their offspring, 37 of 39 liveborn children. After 12 months postnatally, serologically verified congenital toxoplasmosis appeared in 4 children. All these children had persisting IgG at the age of 12 months by both the dye test and the IgG enzyme-linked immunosorbent assay. All the congenitally infected infants had also specific IgM and IgA and showed significant increases in avidity of specific IgG during the 12-month follow-up. One of them had a unilateral retinal scar and intracranial calcifications. An additional 3 infants of the mothers with primary infection during early pregnancy presented with unilateral retinal scars but without seroresponses during the first 12 months of life. Maternal high avidity of IgG during the first trimester is a strong indicator against primary infection during pregnancy; the fetuses of such mothers are at low risk for congenital toxoplasmosis.

Upper gastrointestinal symptoms in the third trimester of the normal pregnancy

OBJECTIVES

To report on the prevalence of well-being, heartburn, nausea, and vomiting related to gestational week, parity, and age in the third trimester of the normal pregnancy.

STUDY DESIGN

Self-administered questionnaire filled in daily by 180 women from 31st gestational week to delivery.

RESULTS

The study was completed by 120 women. The weekly prevalence of well-being decreased from 50% at the 31st gestational week to 24% at the 42nd gestational week (P = 0.00001). The weekly prevalence of heart-burn (approximately 60%), nausea (approximately 16%) and vomiting (approximately 7%) was nearly constant throughout the study period. Well-being was inversely related to parity, (P = 0.006), heartburn positively related to age (P = 0.016), and nausea and vomiting inversely related to age (P = 0.003 and P = 0.044).

CONCLUSION

Discomforts are customary in the third trimester of normal pregnancy. However, heartburn and especially nausea and vomiting appeared occasionally and were not present for longer periods. The findings that heartburn, nausea and vomiting had different relations to age may suggest different etiologies.

Detection by enzyme immunosorbent assay of Toxoplasma gondii IgG antibodies in dried blood spots on PKU-filter paper from newborns

Different ways of eluting IgG antibodies against Toxoplasma gondii from blood spots on PKU filter papers from newborns were examined, and the eluate was analysed by Enzyme Immunosorbent Assay (EIA). 10-mm diameter discs (method A), and 3-mm discs (method B) were eluted overnight, and 3-mm discs were eluted directly for 2 hours in the EIA wells (method C). Two groups of paired samples were tested: blood spots on the PKU card from the newborn, cord blood, and a venous blood sample from the mother collected shortly after delivery (Group 1, 191 samples); or PKU cards from the newborns and serum collected from the mother during the first trimester (Group 2, 426 samples). The best results were found for Group 1; method A, a sensitivity of 100% (63/63), and a specificity of 100% (128/128) (r = 0.934, P < 0.0001), and for Group 2; method C, a sensitivity of 100% (125/125), and a specificity of 100% (301/301) (r = 0.822, P < 0.0001). When method C, was used on 188 samples stored for 16-18 month at -20 degrees C, a sensitivity of 100% (62/62) and a specificity of 99.2% (125/126) (r = 0.913, P < 0.0001) were found. The PKU filter paper method is reliable and reproducible, and can be used in screening projects based on analysis of neonatal samples, and in epidemiological studies on toxoplasmosis in pregnant women.

Models for prediction of the frequency of toxoplasmosis in pregnancy in situations of changing infection rates

BACKGROUND

Estimation of the number of women infected during pregnancy with Toxoplasma gondii from seroconversion or seroprevalence data meets with various difficulties. Because of the high risk of transmission of the infection to the fetus such infections are however a major concern in pregnancy-related health planning.

METHODS

The expected annual percentage of pregnant women infected with Toxoplasma was calculated using models with varying assumptions with regard to the infection rate, assumed to be independent of age but dependent on calendar time. Three situations were studied: a stable situation, a sudden fall in the infection rate and a gradually declining (slower or faster) infection rate over the lifetime of the pregnant women.

RESULTS

With a constant infection rate, a maximum number of affected pregnancies occurs at a yearly infection rate of 4%. In countries with a strongly decreasing annual infection rate, estimates based on data on the relation between age and seropositivity related to only one period of time tend to overestimate the number of affected pregnancies by as much as 60%.

CONCLUSIONS

In countries in transition from high to low infection rates, it is likely that the influence of decreasing immunity will, at least temporarily, more than outweigh the influence of the falling infection rates, resulting in a higher number of infected pregnant women. The models used can also describe situations with age-dependent variation in the infection rate, and may well apply to other infectious diseases relevant to pregnancy.

Antimicrobial antibodies in Danish slaughterhouse workers and greenhouse workers

As a consequence of contact with animals and animal products slaughterhouse workers might be at risk of infection with pathogenic microorganisms. This hypothesis has been supported by some earlier studies. In this study 217 slaughtermen and a control group of 113 greenhouse workers were investigated for the prevalence of serum antibodies to Toxoplasma gondii, Campylobacter jejuni (IgA and IgG), Yersinia enterocolitica types 3 and 9, Yersinia pseudotuberculosis types I, II, III, IV, and V, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Salmonella typhimurium, and Borrelia burgdorferi. No significant differences were found concerning either frequency of positive tests or magnitude of titers. The prevalence of toxoplasma antibodies was remarkably high in both groups.

Experimental infection with Toxoplasma gondii in farmed mink (Mustela vison S.)

Live Toxoplasma gondii tissue cysts (Strain 119) were administered orally to five mink (Mustela vison S.) and five mink were inoculated with a suspension of ultrasonicated Toxoplasma gondii trophozoites (RH-strain). Seroconversion was observed in all animals administered live T. gondii cysts indicating that infection was established. Likewise seroconversion was observed in three out of four animals administered ultrasonicated T. gondii trophozoites. Faecal shedding of oocysts of T. gondii was not demonstrated in any of the infected animals. Histologically chronic meningitis with calcification was seen in all animals. Cerebral T. gondii tissue cysts were detected in four animals administered live tissue cysts. The study demonstrates that mink can be experimentally infected with T. gondii, thus representing a potential infection source for man, when considering the pelting procedure.

Antibody response to a major human Pneumocystis carinii surface antigen in patients without evidence of immunosuppression and in patients with suspected atypical pneumonia

IgG and IgM antibodies to a purified human Pneumocystis carinii surface antigen (gp95) were measured in 694 serum specimens from two different population groups using an EIA technique. In a population of 441 patients with no evidence of immunosuppression, the percentage of persons positive for IgG antibodies to gp95 was significantly lower in the age group 1 to 9 years (30%, 23/77) compared to persons 10 to 19 years old (56%, 49/88). In the age group 1 to 14 years there was a significant correlation between the percentage of persons with IgG antibodies to gp95 and age. In 106 consecutive patients under evaluation due to atypical pneumonia, 76 patients showed no change in the titre of antibodies to Legionella spp. or Mycoplasma pneumoniae in two consecutive serum samples. Three of these 76 patients (4%) demonstrated an increase in the level of IgG antibodies to gp95 in the paired samples. One of these patients had a verified Pneumocystis carinii pneumonia, and the two others were elderly men in whom no microbiological diagnosis of the pneumonia was established. Thus, it is concluded that IgG antibodies to gp95 develop in the majority of nonimmunosuppressed persons before the age of 13. Furthermore, Pneumocystis carinii pneumonia should be considered in the differential diagnosis in patients suspected of having atypical pneumonia.

Prevalence, incidence and geographical distribution of Toxoplasma gondii antibodies in pregnant women in Denmark

The purpose of this study was to determine the prevalence and incidence of toxoplasmosis in pregnant women in Denmark, and to estimate the incidence of congenital toxoplasmosis. Consecutive serum samples from 5,402 women were analysed for specific IgG and IgM Toxoplasma gondii antibodies by EIA. The prevalence of IgG antibodies was 27.4%. The seroconversion rate was estimated to be 1.16% per year (SE = 0.0017) in all age groups, consistent with an incidence of acute toxoplasmosis in pregnant women of 0.65%. Specific IgM antibodies were present in sera from 29 women. Based on an assumed maternofetal transmission rate of 50%, the incidence of congenital toxoplasmosis was estimated to be 0.33%. Based on these data it is predicted that about 410 pregnant women are infected with T. gondii every year in Denmark, and that about 200 children every year are infected in utero by T. gondii. There was no difference in the prevalence of antibodies in women from rural or urban areas, or from different parts of Denmark.

[Parasitic diseases in patients with impaired immune response. Clinical picture and diagnosis]

Patients with impaired immune system are frequently infected with various parasitic diseases. The clinical picture is characterized by unusual manifestations and frequently severe recurrences of infections which are not normally serious. Some almost parasitic microorganisms produce symptoms exclusively in patients with impaired immune system. Parasitic infections have become increasingly common with the increasing number of patients who live for prolonged periods with impaired immune systems, often as a result of infection with HIV. Among the numerous parasitic infections which are observed in man, there are a few which occur particularly frequently in patients with impaired immune systems. This is a brief review of the clinical pictures and diagnostic options in parasitic disease in individuals with impaired immune system with particular emphasis on infections caused by: Pneumocystis carinii, Toxoplasma gondii, Cryptosporidium ssp., Microspora, Entamoeba histolytica, Leishmania ssp., and Strongyloides stercoralis. In patients with impaired immunity, parasitic infections frequently cause nonspecific symptoms and, on account of the impaired immunity, antibodies to the parasite are not always produced. The diagnosis of these infections is, therefore, based on morphological demonstration of the microorganism concerned, culture, specific antigen or DNA defections.

[Congential toxoplasmosis and ocular involvement. A review with 6 case reports]

A review is presented of the ocular affections in congenital toxoplasmosis. The epidemiological, pathogenetic and pathological conditions are reviewed together with the clinical manifestations and the diagnostic and therapeutic possibilities. On the basis of incidence investigations and knowledge from the literature, it must be assumed that approximately 190 infants with congenital toxoplasmosis are born annually in Denmark. Only approximately 15% of the infections will be symptom-producing and will be diagnosed neonatally, but more than 85% of the children with congenital toxoplasmosis will develop chorioretinitis on delivery or later in life and this will frequently cause reduction in vision or blindness. Congenital toxoplasmosis must be regarded as the commonest cause of chorioretinitis and it is probable that congenital toxoplasmosis and chorioretinitis due to toxoplasmosis are considerably underdiagnosed in Denmark. Treatment of congenital toxoplasmosis from birth improve the prognosis. Toxoplasmosis should be suspected in all cases of chorioretinitis. When antibodies to Toxoplasma gondii are demonstrated and the clinical picture is compatible with toxoplasmosis and when there is no other diagnosis, anti-Toxoplasma treatment should be considered. It is important to inform pregnant women about prophylactic measures. If investigations for toxoplasmosis were introduced in the prenatal or perinatal examinations, treatment could be initiated from birth and the diagnosis could be confirmed by possible activation of the chorioretinitis at a later date. Six case reports are presented.

[Lactic acidosis associated with metformin]

Lactic acidosis is an extremely rare but serious complication of treatment with metformin. In order to avoid lactate acidosis, it is important to select patients correctly and to ensure that contraindications such as cases of renal involvement, advanced age and chronic alcoholism are observed prior to treatment with metformin. In addition, it is necessary to carry out meticulous follow-up control of the patients with annual investigations of renal and hepatic functions and clinical assessment approximately four times per annum with the object of revealing commencing symptoms of diabetes and ischaemic conditions. In this manner, the majority of cases of lactate acidosis can be avoided.

[Laparoscopic sterilization in women using Filshie clips]

A material of 194 women sterilized laparoscopically using Filshie clips was followed for 16-51 months. The method is economical (short stay in hospital) and with little damage to the tube. Only few complaints and no complications were recorded. One woman became pregnant in the observation period, a failure rate of 0.5%. According to the literature the potential for reversal seems very good. The method seems to have some advantages over other methods in common use for female sterilization.

Maternal bilirubin, cord bilirubin, and placenta function at delivery and the development of jaundice in mature newborns

The study material comprised 213 newborns with a birth weight above 2000 g, and their mothers. At delivery, blood samples were obtained from the umbilical cord and the mother's cubital vein for determination of the transplacental bilirubin gradient and assessment of placental function by means of the HPL concentration in the maternal blood. The HPL concentration showed no relation to the transplacental bilirubin gradient or the umbilical cord bilirubin concentration. Therefore, to the extent that the HPL concentration reflects the rate constants for bilirubin transfer, an increased transplacental bilirubin gradient or an increased cord bilirubin concentration could not be explained by an impaired ability of the placenta to transfer bilirubin. When the infants who became jaundiced were compared with the non-jaundiced, significantly higher transplacental bilirubin gradient (p less than 0.00001), cord bilirubin (p less than 0.00001) and maternal bilirubin values at the time of delivery (p less than 0.03) were found among the jaundiced infants. On the basis of the results it was possible to define subgroups of infants with significantly higher/lower risk of subsequent jaundice.