Properties of basal dendrites of layer 5 pyramidal neurons: a direct patch-clamp recording study

Basal dendrites receive the majority of synapses that contact neocortical pyramidal neurons, yet our knowledge of synaptic processing in these dendrites has been hampered by their inaccessibility for electrical recordings. A new approach to patch-clamp recordings enabled us to characterize the integrative properties of these cells. Despite the short physical length of rat basal dendrites, synaptic inputs were electrotonically remote from the soma (>30-fold excitatory postsynaptic potential (EPSP) attenuation) and back-propagating action potentials were significantly attenuated. Unitary EPSPs were location dependent, reaching large amplitudes distally (>8 mV), yet their somatic contribution was relatively location independent. Basal dendrites support sodium and NMDA spikes, but not calcium spikes, for 75% of their length. This suggests that basal dendrites, despite their proximity to the site of action potential initiation, do not form a single basal-somatic region but rather should be considered as a separate integrative compartment favoring two integration modes: subthreshold, location-independent summation versus local amplification of incoming spatiotemporally clustered information.

Eczematous skin reaction to atopy patch testing with cockroach in patients with atopic dermatitis

BACKGROUND: Aeroallergens from house dust mite (HDM) may be an important trigger in a subgroup of patients with atopic dermatitis (AD). HDM and cockroach (CR) contain cross-reactive allergens, such as tropomyosin. OBJECTIVE: To investigate the diagnostic value of patch testing with an aeroallergen and the role of CR allergen and HDM allergen in persons with AD. METHODS: We performed skin prick tests (SPT) with a panel of common aeroallergens and total serum immunoglobulin (Ig)E and specific IgE tests for CR and HDM on 23 patients with AD and 9 nonatopic control participants. Atopy patch tests (APT) were performed with CR and HDM extracts on clinically uninvolved skin on the back, and evaluated after 48 and 72 hours. RESULTS: A positive APT reaction to CR was found in 10/23 (43%) patients with AD. No positive reactions were observed in the nonatopic control participants. Positive APT reactions for CR showed no significant correlation with SPT or specific IgE levels for this allergen. Twelve of the 23 (52%) patients with AD were also sensitized to HDM. There was no significant correlation between positive results for SPT, APT, and specific IgE to CR and HDM. CONCLUSION: We demonstrate that CR allergens can induce positive patch test reactions in patients with AD. The absence of a significant correlation to SPT and specific IgE antibodies suggests that T-cell- and IgE-sensitization may be mediated by different allergens. There was no significant relationship between CR and HDM sensitivity, thus indicating no major cross-reactivity.

Global biomass burning: a synthesis and review of Holocene paleofire records and their controls

We synthesize existing sedimentary charcoal records to reconstruct Holocene fire history at regional, continental and global scales. The reconstructions are compared with the two potential controls of burning at these broad scales – changes in climate and human activities – to assess their relative importance on trends in biomass burning. Here we consider several hypotheses that have been advanced to explain the Holocene record of fire, including climate, human activities and synergies between the two. Our results suggest that 1) episodes of high fire activity were relatively common in the early Holocene and were consistent with climate changes despite low global temperatures and low levels of biomass burning globally; 2) there is little evidence from the paleofire record to support the Early Anthropocene Hypothesis of human modification of the global carbon cycle; 3) there was a nearly-global increase in fire activity from 3 to 2 ka that is difficult to explain with either climate or humans, but the widespread and synchronous nature of the increase suggests at least a partial climate forcing; and 4) burning during the past century generally decreased but was spatially variable; it declined sharply in many areas, but there were also large increases (e.g., Australia and parts of Europe). Our analysis does not exclude an important role for human activities on global biomass burning during the Holocene, but instead provides evidence for a pervasive influence of climate across multiple spatial and temporal scales.

Association of bilateral acute anterior uveitis with a capsaicin patch

PURPOSE To report a case of bilateral acute anterior uveitis in association with the application of an analgesic transdermal capsaicin patch. METHODS Case report and review of literature. RESULTS A 38-year-old woman suffered from bilateral acute anterior uveitis, manifesting 12-24 h after application of an analgesic capsaicin patch (Isola Capsicum N Plus) that served to alleviate muscular neck pain. Systemic immune-mediated and infectious diseases were excluded by medical history and laboratory testing. Control of inflammation was achieved with topical corticosteroid treatment within 1 week. Over the course of a 1-year follow-up, no further recurrence of uveitis was observed. CONCLUSIONS The case suggests a possible association of capsaicin-containing transdermal patches and acute anterior uveitis.