Stage-specific functions of Semaphorin7A during adult hippocampal neurogenesis rely on distinct receptors

The guidance protein Semaphorin7A (Sema7A) is required for the proper development of the immune and nervous systems. Despite strong expression in the mature brain, the role of Sema7A in the adult remains poorly defined. Here we show that Sema7A utilizes different cell surface receptors to control the proliferation and differentiation of neural progenitors in the adult hippocampal dentate gyrus (DG), one of the select regions of the mature brain where neurogenesis occurs. PlexinC1 is selectively expressed in early neural progenitors in the adult mouse DG and mediates the inhibitory effects of Sema7A on progenitor proliferation. Subsequently, during differentiation of adult-born DG granule cells, Sema7A promotes dendrite growth, complexity and spine development through β1-subunit-containing integrin receptors. Our data identify Sema7A as a key regulator of adult hippocampal neurogenesis, providing an example of how differential receptor usage spatiotemporally controls and diversifies the effects of guidance cues in the adult brain

High-field Zeeman effect of shallow acceptors in germanium

Zeeman absorption spectra have been obtained for B and Ga in Ge for B∥〈100〉 in the Voigt configuration with plane-polarized radiation. All twelve allowed transitions were observed for both the G and D lines. The corresponding excited states of these two lines for both impurities behave identically; two recent theoretical results are in good agreement. The measurements are a sensitive probe of the ground states; there are differences between the behavior of these for the two acceptors

Limitations of compression ultrasound for the detection of symptomless postoperative deep vein thrombosis

Compression ultrasonography is regarded as the non-invasive gold-standard to detect deep vein thrombosis (DVT) in patients presenting with symptoms. However, its use as a screening method in symptom-free postoperative patients at high risk of developing DVT remains controversial. In 100 consecutive patients who had undergone craniotomy, we compared the results of bilateral compression ultrasonic measurements of the results of bilateral compression ultrasonic measurements of the entire legs with the outcomes of contrast venography. Proximal DVT was detected in 13 patients, 5 of whom also had an abnormal ultrasonic result (sensitivity 38%, 95% CI 8-69%). Only 5 of the 9 patients with an abnormal ultrasound result for the proximal veins had proximal DVT (positive predictive value, 56%, 18-94%). Calf sonograms were evaluable in 71 of the 91 patients with bilaterally normal ultrasound results for the proximal veins. Of the 16 patients with calf DVT, ultrasound was abnormal in 8 (sensitivity 50%, 25-75%). Overall, ultrasound detected 13 of the 26 patients with proximal or isolated calf DVT (sensitivity 50%, 29-71%). The positive predictive value for the whole leg examination was 41% (24-60%). Most thrombi missed by ultrasound were non-occlusive and smaller than 5 cm. We conclude that compression ultrasound is not useful for screening for DVT in symptom-free postoperative high-risk patient

Clinical utility of real-time compression ultrasonography for diagnostic management of patients with recurrent venous thrombosis

In the diagnostic management of patients with clinically suspected recurrent deep-vein thrombosis (DVT), there are potential limitations to all available diagnostic techniques. Since venous abnormalities may persist for some time after an acute thrombosis, the usefulness of compression ultrasonography (US) for the detection of recurrent DVT may be jeopardized. We determined the rate of normalization of an abnormal compression US test of the popliteal and the common femoral veins in patients after a first episode of proximal DVT. In a cohort of 60 consecutive patients, the test result was normalized in only 29, 44, 54, and 60% of patients at 3, 6, 9, and 12 months, respectively. The investigation shows that for the detection of recurrent DVT of the leg, real-time compression US (using the single criterion of compression of the common femoral and popliteal vein) is of limited value. Future studies need to be performed, using more subtle interpretation of the compression US result, by quantifying the extent of residual thrombus, which may increase the usefulness of this test in patients with recurrent symptom

Exhaled NO level and number of eosinophils in nasal lavage as markers of pollen-induced upper and lower airway inflammation in children sensitive to grass pollen

Exhaled NO level and number of eosinophils in nasal lavage as markers of pollen-induced upper and lower airway inflammation in children sensitive to grass pollen. van Amsterdam JG, Bischoff EW, de Klerk A, Verlaan AP, Jongbloets LM, van Loveren H, Opperhuizen A, Zomer G, Hady M, Spieksma FT, Dormans JA, Steerenberg PA. Laboratory of Health Effects Research, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands. [email protected] OBJECTIVES: This study investigates the upper and lower inflammatory response induced by natural exposure to grass pollen in atopic and non-atopic children. METHODS: After children's atopic profile had been assessed, their nasal lavage fluid (NAL) and exhaled air was sampled once before and once during the pollen season. Level of nitric oxide (NO) was determined in exhaled air, and the following mediators were measured in NAL: ECP, IL-6, IL-8, albumin, uric acid, and urea. The number of eosinophils in NAL was determined after Giemsa staining. During the experiment ozone and pollen levels were measured continuously. RESULTS: During the pollen season the level of grass pollen was 95 pollen grains per cubic metre. At baseline, 8.0% and 5.4% of total cells in NAL of children sensitive to, respectively, house dust mite (HDM) and pollen + HDM were eosinophils, whereas virtually no eosinophils were observed in NAL of non-atopic children. In contrast to the non-atopic and HDM groups, in children sensitive only to grass pollen, grass pollen induced a threefold increase in the percentage of NAL eosinophils and a 2.5-fold increase in the NAL level of ECP ( P<0.05). In all groups, the NAL levels of albumin, uric acid, urea, IL-6 and IL-8 were not significantly increased by pollen exposure. At baseline, children sensitive to HDM showed significantly higher exhaled nitric oxide (eNO) values than non-atopic subjects and children sensitive only to pollen (79 to 141% increase). During pollen exposure eNO of children sensitive only to pollen increased from 35.8 to 64.5 ppb ( P<0.05), whereas no increase in eNO was observed in the other children. CONCLUSION: Pollen-sensitive children show a season-dependent upper and lower airway inflammatory response, resembling the continuous inflammation in HDM-sensitive childre

Report 'Effects of air pollution on allergy'

In the last decade the prevalence of asthma and allergy is increasing. Epidemiological studies have frequently shown that allergic diseases and asthma are more prevalent in children living in areas with relative high traffic intensity. To study whether the urban air pollution adversely affects the allergic responses to pollen and house dust mite, the present study was performed in allergic and non-allergic children living in the city of Utrecht (Zuilen and Ondiep). 119 Schoolchildren were selected and they were divided into 4 groups: children without allergy, and children allergic for pollen, for house dust mite or for both pollen and house dust mite. Besides the completing a diary, the higher and lower respiratory tract of children were investigated using non-invasive sampling procedures. The results show that the levels of air pollution in the region Zuilen/Ondiep, measured in the study, are normal for urban regions and below the current standards. Between the groups with different ethnic origin differences in prevalence of allergic sensitisation were observed. Children sensitised to pollen, house dust mite or to both allergens, do not show an increased prevalence of complaints during exposure to pollen or increased levels of airpollution. This is objectified by the results obtained in the study measuring biomarkers in exhaled air and nasal lavage. In conclusion, children allergic for airway-allergens (based on positive skin test) have significant more respiratory complaints than children who were negative in this test. However, during this study air pollution did neither facilitate a stronger allergic reaction nor did it result in more respiratory complaints in school children living in the regions Zuilen and Ondiep

Acute effect of air pollution on respiratory complaints, exhaled NO and biomarkers in nasal lavages of allergic children during the pollen season

Acute effect of air pollution on respiratory complaints, exhaled NO and biomarkers in nasal lavages of allergic children during the pollen season. Steerenberg PA, Bischoff EW, de Klerk A, Verlaan AP, Jongbloets LM, van Loveren H, Opperhuizen A, Zomer G, Heisterkamp SH, Hady M, Spieksma FT, Fischer PH, Dormans JA, van Amsterdam JG. Laboratory for Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, Bilthoven, The Netherlands. [email protected] During 2 months of the pollen season, the acute and putative adjuvant effect of traffic-related air pollution on respiratory health was investigated in children sensitised to grass pollen or house dust mite (HDM). Respiratory complaints were objectified via measurement of exhaled NO and inflammatory mediators in nasal lavage (NAL). During the study children, skin prick negative (n = 31) or positive to grass pollen (n = 22), HDM (n = 34) or grass pollen + HDM (n = 32), kept a daily diary on respiratory symptoms, and NAL and exhaled air was sampled twice a week. The level of air pollutants and pollen was monitored continuously. Like children sensitised to HDM, those sensitised to pollen reported respiratory complaints (shortness of breath, itchy eyes or blocked nose) more frequently than non-sensitised children during (but not before) the pollen season; the respiratory complaints of sensitised children were independent of the pollen level. In addition, exposure to increased levels of PM(10) induces 'shortness of breath' in pollen- and HDM-sensitised children, whereas ozone induces a blocked nose in HDM-sensitised children. Combined exposure to PM(10) + pollen and O(3) + pollen induces a blocked nose in both HDM-sensitised children and children sensitised to pollen + HDM. Significant positive associations were found between eNO and the levels of NO(2), CO, PM(2.5) and pollen in both sensitised and non-sensitised children. At the start of the pollen season, the NAL concentration of eosinophils and ECP in pollen-sensitised children was increased compared to winter, but their levels were not further affected by increased exposure to pollen or air pollution. In conclusion, during the pollen season, sensitised children continuously report a high prevalence of respiratory complaints which coincides with increased levels of upper and lower airway inflammatory markers. No additional pro-inflammatory effect of air pollution was observed, which indicates that air pollution does not facilitate allergen-induced inflammatory responses. Copyright 2003 S. Karger AG, Base

Report &apos;Effects of air pollution on allergy&apos;

In the last decade the prevalence of asthma and allergy is increasing. Epidemiological studies have frequently shown that allergic diseases and asthma are more prevalent in children living in areas with relative high traffic intensity. To study whether the urban air pollution adversely affects the allergic responses to pollen and house dust mite, the present study was performed in allergic and non-allergic children living in the city of Utrecht (Zuilen and Ondiep). 119 Schoolchildren were selected and they were divided into 4 groups: children without allergy, and children allergic for pollen, for house dust mite or for both pollen and house dust mite. Besides the completing a diary, the higher and lower respiratory tract of children were investigated using non-invasive sampling procedures. The results show that the levels of air pollution in the region Zuilen/Ondiep, measured in the study, are normal for urban regions and below the current standards. Between the groups with different ethnic origin differences in prevalence of allergic sensitisation were observed. Children sensitised to pollen, house dust mite or to both allergens, do not show an increased prevalence of complaints during exposure to pollen or increased levels of airpollution. This is objectified by the results obtained in the study measuring biomarkers in exhaled air and nasal lavage. In conclusion, children allergic for airway-allergens (based on positive skin test) have significant more respiratory complaints than children who were negative in this test. However, during this study air pollution did neither facilitate a stronger allergic reaction nor did it result in more respiratory complaints in school children living in the regions Zuilen and Ondiep.VWSDirectie Preventie Onderzoek en Gezondhei