Freeze-thawing of breast milk does not prevent cytomegalovirus transmission to a preterm infant

Freezing human milk is recommended to inactivate cytomegalovirus (CMV). A case of a preterm infant exclusively receiving frozen breast milk from his CMV seropositive mother showed that storage of breast milk for two months at -20 degrees C did not prevent symptomatic postnatal CMV infection.

Age and seasonal variation in the transition rates and detectability of Plasmodium falciparum malaria

The effect of acquired immunity on the duration of Plasmodium falciparum infections is unclear, although this is an important term in models of malaria transmission. It is problematical to determine the duration of infections because of the difficulty of distinguishing persisting infections from new ones, and because parasite densities are often transiently below the limit of detection. We recently developed a dynamic model for infection incidence, clearance and detection of multiple genotype P. falciparum infections and fitted it to a panel dataset from a longitudinal study in Northern Ghana. We now extend this model to allow for seasonal and age variation in infection rates and also age dependence in clearance and in detectability of infections. These models indicate that there is seasonal variation in the infection rate, and age dependence in detectability. The best fitting models had no age dependence in infection or clearance rates, suggesting that acquired immunity mainly affects detectability.

Association of a new mannose-binding lectin variant with severe malaria in Gabonese children

Mannose-binding lectin (MBL2) variants that decrease the plasma level of the protein or encode dysfunctional proteins are frequently associated with the severity of a number of infections and autoimmune disorders. The high frequencies of these variants in most populations of the world are probably maintained by some selective advantage against widespread diseases. We found 14 new MBL2 allelic haplotypes, two of them with non-synonymous variants, by screening 136 children with uncomplicated malaria, 131 children with severe malaria and 39 older healthy schoolchildren. We also found a significant association of a novel variant with susceptibility to severe malaria (P=0.010). Increased MBL plasma levels and corresponding MBL2 genotypes were associated with lower concentration of several cytokines and chemokines in plasma of malaria patients. We suggest that malaria could have been one of the evolutionary driving forces shaping the MBL2 polymorphism in the African population.

Correlation with digital dermoscopic images can help dermatopathologists to diagnose equivocal skin tumours

BACKGROUND

A variety of pigmented skin tumours can lead to diagnostic difficulties in dermatopathology.

OBJECTIVES

To investigate whether the interobserver agreement between histopathological diagnoses of equivocal pigmented tumours made by two referral centres can be improved by additional use of dermoscopic images.

MATERIAL AND METHODS

Retrospective study using 160 tumours excised in the pigmented skin lesions clinic in Graz and 141 from Tübingen. Tumours were diagnosed in the referring centres using clinical data, histopathology and, if required, immunohistochemistry. The tumours were initially diagnosed as 74 melanomas, 218 melanocytic naevi and nine nonmelanocytic tumours. Haematoxylin and eosin sections, patients' age and sex, tumour localization and digital dermoscopic images were then exchanged between the participating centres. Then, diagnoses were made initially based solely on dermatopathology and clinical information. After a washout phase, the same sections were reevaluated with the additional use of dermoscopic images. The main outcome measures were the Cohen's kappa-coefficients of the initial diagnoses of the centre submitting the cases and the diagnoses of the other centre without and with dermoscopy.

RESULTS

The kappa-coefficient between the initial diagnoses with those made by the second centre without dermoscopy was 0.90 in Graz, 0.73 in Tübingen, and 0.81 overall. With the additional use of dermoscopy the kappa-value was invariably high with 0.89 in Graz, and improved to 0.87 in Tübingen, and to 0.88 overall.

CONCLUSIONS

The additional use of digital dermoscopic images further improved the overall very good agreement of histopathological diagnoses between two referral centres.

Tirofiban (Aggrastat®) Protects Platelets and Decreases Platelet-Granulocyte Binding in an Extracorporeal Circulation Model

OBJECTIVES

Extracorporeal circulation (ECC) induces platelet activation and inflammation with potentially life-threatening organ dysfunction. Short-acting GP IIb/IIIa inhibitors like tirofiban and eptifibatide protect platelets during ECC without increasing bleeding complications and may reduce inflammation. This study investigates anti-thrombotic and anti-inflammatory effects of different platelet inhibitors.

METHODS

Control (untreated) and treated (using either 150 ng/mL tirofiban, 2.5 microg/mL eptifibatide, 0.7 microg/mL milrinone, 15 microg/mL dipyridamol, or 300 KIU/mL aprotinin) heparinized blood of healthy volunteers (n = 6) was recirculated in a well-established ECC model (Chandler loop). Percentage of platelet aggregates, P-selectin-expressing (activated) platelets, CD15-positive aggregates (indicating proinflammatory platelet-granulocyte binding), and platelet counts were determined before (baseline) and after 30 minutes recirculation in unstimulated and ADP-stimulated samples using flow cytometry. Statistical analysis was performed using multifactor ANOVA after transforming the data (logarithms for counts and log odds for percentages). Least square means were backtransformed to obtain appropriate means and their 95 % confidence intervals. Multiple post-hoc comparisons were performed by Tukey's HSD test with a global alpha of 5 %.

RESULTS

Significant inhibition was observed for: 1) ECC-induced platelet aggregation by tirofiban (unstimulated: 2.2-fold/stimulated: 2.46-fold), eptifibatide (unstimulated: 1.96-fold/stimulated: 2.65-fold), and milrinone (unstimulated: 1.87-fold/stimulated: 1.37-fold); 2) ECC-induced P-selectin expression by tirofiban (unstimulated: 3.95-fold/stimulated: 2.54-fold), and eptifibatide (unstimulated: 5.87-fold/stimulated: 3.28-fold); 3) ECC-induced platelet loss by tirofiban (1.27-fold), and eptifibatide (1.25-fold); 4) ECC-induced platelet-granulocyte binding by tirofiban (unstimulated: 2.25-fold/stimulated: 1.59-fold), but not by eptifibatide.

CONCLUSIONS

Amongst the investigated drugs only GP IIb/IIIa inhibitors decreased activation, aggregation, and loss of platelets during ECC but acted differently on platelet-granulocyte interaction. A short-acting GP IIb/IIIa inhibitor with the potential to inhibit platelet activation and platelet-leukocyte interaction should be considered both for platelet protection and inhibition of platelet-mediated inflammation during ECC.

New standardised texts for assessing reading performance in four European languages

AIMS

To develop standardised texts for assessing reading speed during repeated measurements and across languages for normal subjects and low vision patients.

METHODS

10 texts were designed by linguistic experts in English, Finnish, French, and German. The texts were at the level of a sixth grade reading material (reading ages 10-12 years) and were matched for length (830 (plus or minus 2) characters) and syntactic complexity, according to the syntactic prediction locality theory of Gibson. 100 normally sighted native speaking volunteers aged 18-35 years (25 per language) read each text aloud in randomised order. The newly designed text battery was then applied to test the reading performance of 100 normally sighted native speaking volunteers aged 60-85 years (25 per language).

RESULTS

Reading speed was not significantly different with at least seven texts in all four languages. The maximum reading speed difference between texts, in the same language was 6.8% (Finnish). Average reading speeds (SD) in characters per minute are, for the young observer group: English 1234 (147), Finnish 1263 (142), French 1214 (152), German 1126 (105). The group of older readers showed statistically significant lower average reading speeds: English 951 (97), Finnish 1014 (179), French 1131 (160), German 934 (117).

CONCLUSION

The authors have developed a set of standardised, homogeneous, and comparable texts in four European languages (English, Finnish, French, German). These texts will be a valuable tool for measuring reading speed in international studies in the field of reading and low vision research.

PCV chemotherapy for recurrent glioblastoma

The authors administered procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU, lomustine), and vincristine (PCV) to 86 patients with recurrent glioblastoma. There were three partial responses, but no complete responses. Median progression-free survival was 17.1 weeks and progression-free survival at 6 months was 38.4%. World Health Organization grade III/IV hematologic toxicity was common (25.6%), but nonhematologic toxicity was mild.

Distribution of survival times of deliberate Plasmodium falciparum infections in tertiary syphilis patients

Survival time data of Plasmodium falciparum infections from deliberate infection of human subjects with P. falciparum between 1940 and 1963 as a treatment for neurosyphilis in the USA (Georgia) have been used to test the fits of five commonly used parametric distributions for survival times using quantile-quantile plots. Our results suggest that the best fit is obtained from the Gompertz or Weibull distributions. This result has important implications for mathematical modelling of malaria, which has for the past century exclusively assumed that the duration of malaria infections has an exponential distribution. It is desirable to know the correct distribution because its shape profoundly influences the length of monitoring needed in an intervention programme for eliminating or reducing malaria.

A meta-analysis of hyperfractionated and accelerated radiotherapy and combined chemotherapy and radiotherapy regimens in unresected locally advanced squamous cell carcinoma of the head and neck

Background

Former meta-analyses have shown a survival benefit for the addition of chemotherapy (CHX) to radiotherapy (RT) and to some extent also for the use of hyperfractionated radiation therapy (HFRT) and accelerated radiation therapy (AFRT) in locally advanced squamous cell carcinoma (SCC) of the head and neck. However, the publication of new studies and the fact that many older studies that were included in these former meta-analyses used obsolete radiation doses, CHX schedules or study designs prompted us to carry out a new analysis using strict inclusion criteria.

Methods

Randomised trials testing curatively intended RT (≥60 Gy in >4 weeks/>50 Gy in <4 weeks) on SCC of the oral cavity, oropharynx, hypopharynx, and larynx published as full paper or in abstract form between 1975 and 2003 were eligible. Trials comparing RT alone with concurrent or alternating chemoradiation (5-fluorouracil (5-FU), cisplatin, carboplatin, mitomycin C) were analyzed according to the employed radiation schedule and the used CHX regimen. Studies comparing conventionally fractionated radiotherapy (CFRT) with either HFRT or AFRT without CHX were separately examined. End point of the meta-analysis was overall survival.

Results

Thirty-two trials with a total of 10 225 patients were included into the meta-analysis. An overall survival benefit of 12.0 months was observed for the addition of simultaneous CHX to either CFRT or HFRT/AFRT (p < 0.001). Separate analyses by cytostatic drug indicate a prolongation of survival of 24.0 months, 16.8 months, 6.7 months, and 4.0 months, respectively, for the simultaneous administration of 5-FU, cisplatin-based, carboplatin-based, and mitomycin C-based CHX to RT (each p < 0.01). Whereas no significant gain in overall survival was observed for AFRT in comparison to CFRT, a substantial prolongation of median survival (14.2 months, p < 0.001) was seen for HFRT compared to CFRT (both without CHX).

Conclusion

RT combined with simultaneous 5-FU, cisplatin, carboplatin, and mitomycin C as single drug or combinations of 5-FU with one of the other drugs results in a large survival advantage irrespective the employed radiation schedule. If radiation therapy is used as single modality, hyperfractionation leads to a significant improvement of overall survival. Accelerated radiation therapy alone, especially when given as split course radiation schedule or extremely accelerated treatments with decreased total dose, does not increase overall survival.

Conventional histology vs. three-dimensional histology in lentigo maligna melanoma

BACKGROUND

Conventional surgery for lentigo maligna melanoma (LMM) is based on normal histological evaluation. However, such evaluation leaves diagnostic gaps. In contrast, complete three-dimensional (3D) histology of excision margins permits accurate detection of continuously spreading tumour strands like those of LMM. These can be specifically excised in tumour-positive areas with smaller excision margins, and better cosmesis and function. To date there have been no controlled studies of micrographic surgery of LMM.

OBJECTIVES

Clinical parameters and surgical strategies influencing the prognosis of patients with LMM were evaluated in a prospective study of melanoma patients in the Department of Dermatology of the University of Tübingen (1980-99).

METHODS

The 292 LMMs comprised 7.4% of 3960 primary stage I and II melanomas treated during this period. One hundred and thirty-six patients in this group (46.6%) underwent surgery on the basis of 3D histology.

RESULTS

The geometric mean excision margins were significantly smaller in the 3D histology group (P < 0.0001). Patients with micrographic surgery had fewer recurrences. Multivariate analysis of clinical, histological and surgical variables was carried out, and tumour thickness and 3D histology proved to be independent, significant factors for the prognosis of recurrence-free survival (relative risk, RR 2.08, P < 0.0001 and RR 2.11, P = 0.0037, respectively). There were no melanoma-related deaths in the 3D histology group. All 16 melanoma-related deaths were observed among the 156 patients of the conventional histology group (10.3%).

CONCLUSIONS

Excision of LMM using 3D histology resulted in a twofold lower probability of recurrence and twofold smaller excision margins. 3D histology is a valuable diagnostic tool and can be used in the management of LMM because of the latter's pattern of continuous tumour spread.

Ergonomic testing of two different types of handles via virtual reality simulation

BACKGROUND

Ergonomics in laparoscopic surgery is an unsolved problem. Deficiencies of the instrument handles are well-known and described in several reports and studies. Today, virtual training modules for laparoscopic surgery are available. The aim of this study was to evaluate the ability of a virtual reality (VR) simulator to determine the ergonomic properties of two different laparoscopic instrument handles.

METHODS

Two different types of handles, a ring and an axial handle from Richard Wolf, were used to perform the short clip and cut task of the Xitact 500 LS simulator. The task was repeated every 2 days for a period of 5 weeks. After every trial the volunteers were asked structured questions about their preferences while using the two handles.

RESULTS

The axial handle was superior or equal to the ring handle in all criteria. Learning curves over the entire time and day by day were similar. No differences were found for travel distances and error rates, but task times were different for both handles. The subjects preferred the axial handle at the end of the study.

CONCLUSION

It is possible to determine differences in ergonomics of handle design with a VR trainer. In this study, the Richard Wolf axial handle was superior to the ring handle.

[Detection of high-risk human papillomavirus (HPV) E6 and E7 oncogene transcripts increases the specificity of the detection of a cervical intraepithelial neoplasia (CIN)]

AIMS

The oncogenic potential of the high-risk human papillomavirus (HR-HPV) genotypes depends on the expression of the viral oncogenes E6 and E7. Thus, the detection of these transcripts could serve as a factor in the evaluation of a woman's risk of development of cervical intraepithelial neoplasia (CIN).

METHODS

A nested RT-PCR assay for the detection of E6/E7 oncogene transcripts of all known HR-HPV genotypes was established. Cervical scrapes of 779 HR-HPV-DNA-positive women exhibiting all grades of CIN were examined.

RESULTS

Spliced E6/E7 oncogene transcripts of all the HR-HPVs were detected in numerous samples. In 459 cases with agreement between the cytologic and histologic findings, the prevalence increased with lesion severity: CIN 0, 18%; CIN I, 58%; CIN II, 77%; CIN III, 84%. While sensitivity and negative predictive value of HR-HPV DNA-positivity for the detection of a CIN lesion were significantly (p < 0.0001) higher than those of E6/E7 mRNA positivity (90.3% vs. 65.5% and 93% vs. 83.1%), the opposite was true for the specificity and positive predictive value (72.8 % vs. 95.2%) and 65.1% vs. 88.5%, p < 0.0001). Preliminary follow-up data in 120 initially HPV-16 DNA-positive women revealed the development, persistence or progression of a CIN lesion in 33% (8/24) of HR-HPV DNA-positive and E6/E7 mRNA-negative women, compared to 93% (66/71, p < 0.0001) in women in whom transcriptional activity of the E6/E7 oncogenes was detectable.

CONCLUSIONS

Besides the identification of HPV DNA, the detection of HR-HPV E6/E7 oncogene transcripts may serve as a valuable tool in increasing the specificity of HPV testing.

Bewertung von Präzision und Genauigkeit der digitalen Oberflächenphotogrammetrie mit dem DSP 400 System / Assessment of Precision and Accuracy of Digital Surface Photogrammetry with the DSP 400 System

The objective of the present study was to evaluate the precision and accuracy of facial anthropometric measurements obtained through digital 3-D surface photogrammetry with the DSP 400 system in comparison to traditional 2-D photogrammetry. Fifty plaster casts of cleft infants were imaged and 21 standard anthropometric measurements were obtained. For precision assessment the measurements were performed twice in a subsample. Accuracy was determined by comparison of direct measurements and indirect 2-D and 3-D image measurements. Precision of digital surface photogrammetry was almost as good as direct anthropometry and clearly better than 2-D photogrammetry. Measurements derived from 3-D images showed better congruence to direct measurements than from 2-D photos. Digital surface photogrammetry with the DSP 400 system is sufficiently precise and accurate for craniofacial anthropometric examinations.

Bayesian age-stage modelling of Plasmodium falciparum sequestered parasite loads in severe malaria patients

A discrete-time age-stage model is proposed for estimating the number of sequestered parasites in severe malaria patients. A Bayesian Markov chain Monte Carlo (MCMC) approach is used to model the dynamics of Plasmodium falciparum parasitaemia in 107 paediatric patients in a randomized controlled trial of quinine and artemether in Kenya, in whom 4-hourly peripheral parasitaemia determinations were made. The MCMC approach allows the model to be fitted simultaneously to the entire dataset, providing point and interval estimates for both population and individual patient parameters. Analysis of a simulated dataset indicated that the models gave good estimates of the distribution of parasites between different stages on enrolment, for patients with a wide range of initial states. The analysis of the Kenyan patients suggested that there is considerable variation between patients within the same centre, in both the proportion of sequestered parasites and the intrinsic rate of increase of the parasite population in the absence of treatment. The resulting models should prove a useful tool for cross-validating biochemical approaches for estimating the sequestered load.

Detection and typing of human papillomavirus by e6 nested multiplex PCR

A nested multiplex PCR (NMPCR) assay that combines degenerate E6/E7 consensus primers and type-specific primers was evaluated for the detection and typing of human papillomavirus (HPV) genotypes 6/11, 16, 18, 31, 33, 35, 39, 42, 43, 44, 45, 51, 52, 56, 58, 59, 66, and 68 using HPV DNA-containing plasmids and cervical scrapes (n = 1,525). The performance of the NMPCR assay relative to that of conventional PCR with MY09-MY11 and GP5+-GP6+ primers, and nested PCR with these two primer sets (MY/GP) was evaluated in 495 cervical scrapes with corresponding histologic and cytologic findings. HPV prevalence rates determined with the NMPCR assay were 34.7% (102 of 294) in the absence of cervical intraepithelial neoplasia (CIN 0), 94.2% (113 of 120) in the presence of mild or moderate dysplasia (CIN I/II), and 97.8% (44 of 45) in the presence of severe dysplasia (CIN III). The combination of all four HPV detection methods applied in the study was taken as "gold standard": in all three morphological subgroups the NMPCR assay had significantly (P < 0.0001) higher sensitivities than the MY09-MY11 and GP5+-GP6+ assays and sensitivities comparable or equal to those of the MY/GP assay. All 18 HPV genotypes investigated were detected among the clinical samples. The ratio of high- to low-risk HPV genotypes increased from 4:1 (80 of 103) in CIN 0 to 19:1 (149 of 157) in CIN I to III. Multiple infections were detected in 47.9% (124 of 259) of the patients. In conclusion, the novel NMPCR method is a sensitive and useful tool for HPV DNA detection, especially when exact HPV genotyping and the identification of multiple HPV infections are required.

The relationships between the burden of adult parasites, host age and the microfilarial density in human onchocerciasis

We investigate the relationship between the microfilarial density in the skin and the burden of adult female Onchocerca volvulus by analysing pre-control nodulectomy data which allow for a direct approach, independent of exposure. The data of 169 patients in Burkina Faso and 182 patients in Liberia represent savannah and forest onchocerciasis in West Africa, respectively. Whereas in Burkina Faso, a saturating relationship between microfilarial density and worm burden suggests the operation of density-dependent processes within human hosts, the Liberian data show a linear relationship implying no density dependence. The differences may derive from differences between both parasite strains, i.e. the savannah or the forest strain of O. volvulus. Consistently for both parasite strains and independent of the worm burden, the microfilarial density increases with host age emphasising the concept of the acquisition of immunological tolerance. In male hosts in Liberia, the microfilarial density increases stronger with the worm burden than in female hosts, whereas such sex-specific differences cannot be found in Burkina Faso. In the methodological part of this investigation, we suggest the beta-distribution to be most appropriate for describing variability in microfilarial densities and we present an approach to consider the uncertainty in the adult parasite burden which cannot be determined precisely in helminth infections. Implications of density dependence are discussed with respect to immunological processes in the human host and with respect to the success of control programs. The relationships described show that regulatory processes between the parasite and the human host are multi-dimensional, operating within a high degree of biological variability.

MRI-based volumetric differentiation of sporadic cerebellar ataxia

The term idiopathic cerebellar ataxia (IDCA) designates a variety of cerebellar syndromes that may present with a purely cerebellar syndrome (IDCA-C) or with additional extracerebellar features (IDCA-P). Multiple system atrophy is also a sporadic neurodegenerative disorder of unknown origin that may cause prominent cerebellar symptoms (MSA-C). The final neuropathological answer to the question whether IDCA-P and MSA-C represent different varieties of one disease or two distinct entities is still lacking. Three-dimensional MRI-based volumetry allows morphological investigations intra vitam. Volumetric analysis of cerebellum, brainstem and basal ganglia was therefore performed in 46 patients with sporadic cerebellar ataxia and 16 age-matched healthy controls. Patients with dementia were excluded from the study since cognitive impairment is an exclusion criterion for the diagnosis of MSA. Cerebellar patients were clinically divided into two groups: 33 patients with multiple system atrophy with prominent cerebellar symptoms (MSA-C) and 13 patients with extracerebellar features not corresponding to MSA-C (IDCA-P). There was evidence for substantial cerebellar atrophy in both cerebellar groups while additional brainstem atrophy was significantly more pronounced in MSA-C patients. Absolute caudate and putamen atrophy was found to be restricted to single MSA-C individuals while group comparisons of mean volumes did not yield significant differences from controls. Based on the volumetric data, diagnosis could be correctly predicted in 94% of control, 82% of MSA-C and 100% of IDCA-P individuals. The finding of specific imaging characteristics strengthens (i) the value of MRI volumetry in separating MSA-C from other types of sporadic cerebellar ataxia, and (ii) the hypothesis of two independent neurodegenerative disorders in MSA-C and IDCA-P.

Non-invasive determination of effective pulmonary blood flow: evaluation of a simplified rebreathing method

PRIMARY OBJECTIVE

To evaluate a new technical approach to measuring effective pulmonary blood flow (PBF) in mechanically ventilated patients.

RESEARCH DESIGN

Prospective clinical study; evaluation of accuracy and reproducibility.

METHODS

Effective pulmonary blood flow was determined non-invasively in 32 mechanically ventilated patients by using a new rebreathing system (PBF(rb)). Cardiac output corrected for intrapulmonary shunt was taken as reference value (PBF(thd)). Bias, precision and reproducibility of the rebreathing method were calculated from duplicate measurements in each patient.

MAIN RESULTS

The mean difference between PBF(rb) and PBF(thd) was - 0.67 +/- 0.83 l min(-1). The mean difference between duplicate measurements with the rebreathing system was 0.16 +/- 0.36 l min(-1). However, the accuracy of the rebreathing system tended to decrease in patients with PBF levels greater than 6 l min(-1).

CONCLUSIONS

The new device appears to be reliable for determination of PBF values below 6 l min(-1). With this limitation, the present method may be used as a trend-indicator of PBF in mechanically ventilated patients.

Density-dependent parasite establishment suggests infection-associated immunosuppression as an important mechanism for parasite density regulation in onchocerciasis

The modulation of human immune response by filarial parasites has yielded contradictory experimental findings and attracted much controversy. We address the unresolved question of acquisition, establishment and accumulation of Onchocerca volvulus by using a modelling approach that relates computer simulations to cross-sectional data concerning parasite burdens in 913 West African onchocerciasis patients. It is shown that the acquisition of O. volvulus is not constant with host age; instead, the analysis of age profiles of parasite burdens strongly indicate the operation of immunosuppressive processes within the human host, associated with the presence of adult parasites or microfilariae. It is suggested that these processes suppress immunity against incoming infective larvae (L3), which themselves act as an immune modulating component once they have successfully overcome the barrier of concomitant immunity. Suppression of parasite-specific immunity leads to parasite establishment rates which increase along with the parasite burden, but which hardly depend on hyperendemic annual transmission potentials. Children, still immunocompetent due to low parasite burdens, acquire 0.1-0.5 adult female parasites per year, whereas older people, immunosuppressed due to high burdens, acquire 2-4 adult female parasites per year. Differences in parasite establishment between the forest and the savannah strains of O. volvulus are quantified and dynamic aspects of density-dependent parasite establishment discussed.

Evaluation of a commercial IgG/IgM Western blot assay for early postnatal diagnosis of congenital toxoplasmosis

The aim of this study was to evaluate a commercial Western blot IgG/IgM assay for use in the early serological diagnosis of congenital toxoplasmosis. This assay compares the immunological profile of mother and infant and allows differentiation between passive transmitted maternal antibodies and newly synthesized antibodies of the infant within the first 3 months of life. Over a 6-year period (1995-2001), the sera from 169 mothers and their 175 offspring (6 had twins) were examined for specific anti- Toxoplasma gondii IgG, IgM and IgA antibodies with an enzyme-linked immunosorbent assay or an immunosorbent agglutination assay. All mothers had primary Toxoplasma infection during pregnancy. Serological and clinical follow-up of the infants during the first year of life confirmed 36 cases of congenital toxoplasmosis. In 139 cases, infection could be ruled out. Three hundred fifty-one paired samples from 175 mother-child pairs were tested retrospectively for IgG and IgM patterns by Toxoplasma Western blot IgG/IgM (LDBIO Diagnostics, France). The results of conventional serological analysis (immunosorbent agglutination assay or enzyme-linked immunosorbent assay) to detect IgM or IgA were compared with the results of the Toxoplasma Western blot IgG/IgM on samples obtained within the first 3 months of life. The performance of the combination of the two methods was also assessed. At birth, the sensitivity values of conventional serological analysis and the Toxoplasma Western blot were 52% and 67%, with specificity values being 99% and 96%, respectively. Combination of the Western blot and conventional serological analysis increased the sensitivity at birth to 78% and within the first 3 months of life to 85%. Overall, the combination of both methods detected 94% of congenital infections. Therefore, this commercial Western blot represents a useful tool for early postnatal diagnosis of congenital toxoplasmosis.

Immunohistochemical and molecular biological investigations regarding the pathogenesis of extrahepatic biliary atresia. (Part 1: immunohistochemical studies)

INTRODUCTION

The pathogenetic model for biliary atresia presently most favored is that EHBA is the result of a peri- or postnatal bile duct lesion. Several authors demonstrated inflammatory infiltrations in the mesenchymal areas of the liver and thus concluded an infectious genesis. An association of rota-, reo- (and CMV) virus infection with EHBA was suspected, but the presence of these viruses in EHBA could not be reproduced. In view of this controversial debate we found it to be indicated to investigate tissue blocks from the porta hepatis and liver biopsies in children with EHBA by histo- and immunohistochemistry for the quality and quantity of leukocyte infiltrations.

METHODS

31 tissue excidates of the porta hepatis were gained on the occasion of hepatoportoenterostomy, fixed in 4 % buffered formalin and embedded in paraffin. The presence of leukocyte infiltrations and their subpopulations was demonstrated by histochemical reactions and immunohistochemical staining methods using specific antibodies against surface markers. The number of leukocytes and their subpopulations was counted in three different regions of the porta hepatis, the obliterated extrahepatic bile duct, the fibrous mass of the porta hepatis and the transition zone between the fibrous mass and liver parenchyma. A statistical analysis was done.

RESULTS

In EHBA, leukocyte infiltrations consist mainly of macrophages. Antigen-presenting cells and lymphatic cells play a minor role. Lymphatic cells could only be detected in 6 out of 31 tissue preparations. Antigen-presenting cells could only be detected via anti-F13a antibody which shows cross-reactivities, i.e. against macrophages and embryonal tissue. Evaluating the density of leukocyte infiltrations with regard to the different anatomical regions of the porta hepatis we could demonstrate that leukocyte infiltrations are scarce around the rudiment of the bile duct whereas the highest leukocyte density could be found in the fibrous mass of the porta hepatis and the intrahepatic fibrous septs interconnecting the fibrous mass of the porta hepatis with liver parenchyma. Liver parenchyma was mainly free of leukocyte infiltrations with the exception of neutrophilic granulocytes. Regardless of the subpopulations, leukocytes were mainly arranged around the bile ducts of the fibrotic septa.

CONCLUSIONS

Most tissue preparations from children operated on during the 4th-8th week of life show only small leukocyte infiltrations and in the majority of cases no immunocompetent lymphocytes. This leads to the conclusion that a virus infection as an underlying cause for EHBA is very unlikely. Most probably, the observed leukocyte infiltrations are due to an unspecific phagocytotic activity. Comparing our results to reports from Hadchouel et al (9) and Landing et al (12) led us to believe that a pathologic immunoreaction with a possible defective antigen elimination could also be considered as a reason for EHBA.

On the interpretation of age-intensity profiles and dispersion patterns in parasitological surveys

The present paper describes how age-intensity profiles of macroparasite burdens are affected by processes underlying the distribution of the parasite numbers in host populations. In a comparative way, we consider the following 6 processes: (i) age-dependent exposure, (ii) parasite-induced host mortality, (iii) heterogeneity within, the host population, (iv) clumped infection, (v) density-dependent parasite mortality and (vi) density-dependent parasite establishment. For each of these processes, we show typical patterns in the age-intensity profile and provide, if possible, explicit and simple solutions for the age-dependent mean parasite burden and the corresponding dispersion patterns. Emphasis is given to density-dependent parasite establishment and to age-intensity profiles resulting from the superposition of different processes. By means of 2 examples we show that the interpretation of observed patterns can be ambiguous if more than 1 process takes place. These findings underline that age-intensity profiles should be interpreted on the basis of available a priori knowledge about the processes assumed to be involved. For purposes of testing different hypotheses, a simulation program is provided with which discrepancies between model prediction and data can be explored.