Correlation between skin prick test using commercial extract of cow''s milk protein and fresh milk and food challenges

The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of cow's milk protein allergy. It is not known whether commercial extracts have any advantage over fresh milk. The aims of the study were to (i) compare the diagnostic capacity of SPTs for the three main cow's milk proteins (alpha-lactalbumin, casein and beta-lactoglobulin) with fresh milk and (ii) determine a cut-off that discriminates between allergic and tolerant children in a controlled food challenge. A study was carried out on 104 children consecutively attending two paediatric allergy clinics for suspected cow's milk allergy. A clinical history, SPTs with fresh cow's milk and commercial extracts of its three main proteins and a challenge test were performed on all the children. A study of the validity of the prick test was also performed by taking different cut-off points for fresh milk and its proteins. Twenty-eight of 104 challenge tests (26.9%) were positive. At a cut-off point of 3 mm, fresh milk showed the greatest negative predictive value (98%), whereas casein showed the greatest positive predictive value (PPV, 85%). Calculation of 95% predicted probabilities using logistic regression revealed predictive decision points of 12 mm for lactalbumin, 9 mm for casein, 10 mm for beta-lactoglobulin and 15 mm for fresh cow's milk. We found that the greater the number of positive SPTs for milk proteins, the more likely the positive response to challenge. Having a positive SPT for all three milk proteins had PPV of 92.3% and would seem more clinically useful than any cut-off. Both fresh milk and cow's milk extract of the three main proteins could be useful in the diagnostic work-up of cow's milk allergy. Finding positivity to all three cow's milk proteins seems to be a simpler and more useful way of avoiding oral food challenges.     

Iodine-131 metaiodobenzylguanidine scintigraphy for localization of lesions in children with neuroblastoma: comparison with computed tomography and ultrasonography

Iodine-131 metaiodobenzylguanidine (MIBG) scintigraphy, computed tomography (CT) and ultrasonography (US) were used to localize tumour lesions in 28 children with histologically proven neuroblastoma. Overall, a total of 73 lesions were detected on imaging studies. MIBG scintigraphy, CT and US localized 63 (86%), 49 (67%) and 36 (49%) of these lesions, respectively. The findings of the three imaging techniques were concordant in respect of only 31 (42%) of the lesions. The best agreement among MIBG scintigraphy, CT and US was observed for abdominal lesions (the techniques were concordant for 22 of 23 lesions, i.e. 96%). MIBG scintigraphy detected nine out of ten (90%) liver metastases, but agreement with CT and US was observed in only six instances (60%). The imaging findings were concordant in respect of only two (33%) out of six lymph node metastases; the MIBG scan was normal in the other four cases. Imaging agreement was observed for a lesion located in the pelvis. MIBG and CT findings were concordant in four lesions located in the chest, but US was not performed. MIBG scintigraphy depicted the majority (96%) of the skeletal lesions (23/24); CT showed five of these, but, again, US was not performed. The imaging findings were not concordant as regards the remaining five lesions located in different anatomical sites. The results indicated that MIBG imaging is more sensitive that CT and US in localizing the majority of neuroblastoma lesions. Since the metastatic spread of neuroblastoma is unpredictable, we recommend MIBG scintigraphy as the initial imaging modality for staging of these patients. US and, particularly, CT should be performed thereafter to clarify the anatomical detail of the lesions detected on MIBG scans, or when MIBG findings are normal or equivocal.     

Thiamine pyrophosphate determination in whole blood and erythrocytes by high performance liquid chromatography

A sensitive method for the measurement of thiamine pyrophosphate in whole blood and erythrocytes, using a straight-phase high performance liquid chromatography (HPLC), is described. The method was based on sample extraction with trichloracetic acid, conversion of the vitamer to the corresponding high fluorescent thiochrome ester, and separation and measurement of the derivative by HPLC. Evidence for reproducibility and accuracy of the assay is presented. Data indicating the thiamine pyrophosphate levels to be expected in blood and erythrocytes of healthy humans are included.     

Mancozeb adversely affects meiotic spindle organization and fertilization in mouse oocytes

In this study the effects of mancozeb, a widely used ethylenebisdithiocarbamate fungicide, on mouse oocyte meiotic maturation and fertilization were analyzed. Oocyte cumulus cell-complexes were matured in vitro with or without increasing concentrations of the fungicide (from 0.001 to 1 microg/ml) that, due to its different stability in organic solvents and in water, was resuspended either in dimethyl sulfoxide or in culture medium. Although, about 95% of oocytes reached the metaphase II stage; mancozeb-exposed oocytes showed a dose-dependent increase of alterations in spindle morphology, and this negative effect was more evident when the fungicide was resuspended in culture medium. Under the latter culture condition, oocytes matured in the presence of 0.1 and 1 microg/ml mancozeb showed a significant reduction also in the formation of male and female pronuclei. These results indicate that mancozeb can adversely affect mammalian reproductive performance, likely by perturbing microtubular organization during meiotic maturation.     

Mancozeb exposure in vivo impairs mouse oocyte fertilizability

Mancozeb is known to alter reproductive performance in exposed animals, but its specific mechanism of action is still unclear. We investigated whether in female mice of the F1 generation, mancozeb could affect oocyte ability to undergo complete meiotic maturation and fertilization. Female mice were treated with 50 and 500 mg/kg of mancozeb (or vehicle in the controls) from gestational day 2 to postnatal day 20. Results demonstrated that only at the highest dose, mancozeb induced a significant decrease in the number of ovulated eggs. Moreover, at this dose mancozeb caused a significant decrease of fertilizability related to a reduction of the formation of male and female pronuclei.