Amnesic Concentrations of the Nonimmobilizer 1,2-Dichlorohexafluorocyclobutane (F6, 2N) and Isoflurane Alter Hippocampal θ Oscillations In Vivo

Background: Drug-induced temporary amnesia is one of the principal goals of general anesthesia. The nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also termed 2N) impairs hippocampus-dependent learning at relative, i.e., lipophilicity-corrected, concentrations similar to isoflurane. Hippocampal [theta] oscillations facilitate mnemonic processes in vivo and synaptic plasticity (a cellular model of memory) in vitro and are thought to represent a circuit level phenomenon that supports memory encoding. Therefore, the authors investigated the effects of F6 and isoflurane on [theta] oscillations (4-12 Hz).

Methods: Thirteen adult rats were implanted with multichannel depth electrodes to measure the microelectroencephalogram and were exposed to a range of concentrations of isoflurane and F6 spanning the concentrations that produce amnesia. Five of these animals also underwent control experiments without drug injection. The authors recorded the behavioral state and hippocampal field potentials. They confirmed the electrode location postmortem by histology.

Results: The tested concentrations for isoflurane and F6 ranged from 0.035% to 0.77% and from 0.5% to 3.6%, respectively. Isoflurane increased the fraction of time that the animals remained immobile, consistent with sedation, whereas F6 had the opposite effect. Electroencephalographic power in the [theta] band was less when the animals were immobile than when they explored their environment. F6 suppressed the power of oscillations in the [theta] band. Isoflurane slowed [theta] oscillations without reducing total power in the [theta] band.     

Singularities explained: Response to Klein.

Klein [Klein, A. S. (2006). Separating transducer nonlinearities and multiplicative noise in contrast discrimination. Vision Research, 46, 4279-4293] questions the existence of intrinsic singularities in two-alternative force-choice (2AFC) Signal Detection Theory (SDT) models, suggesting that the singularities found in Katkov et al. [Katkov, M., Tsodyks, M., & Sagi, D. (2006a). Singularities in the inverse modeling of 2AFC contrast discrimination data. Vision Research, 46, 259-266; Katkov, M., Tsodyks, M., & Sagi, D. (2006b). Analysis of two-alternative force-choice Signal Detection Theory model. Journal of Mathematical Psychology, 50, 411-420] are due to discarding higher order terms in the Taylor expansion of d' and/or limited to steep psychometric functions. Here we provide some simple intuitive examples that illustrate the results described in Katkov et al. (2006a, 2006b). We show, for the constant noise model, that singularities exist when exact values of d' are computed and that the singularities are not limited to steep psychometric functions. In these cases the disambiguation of the different models requires millions of trials.     

Depression, Night Terrors, and Insomnia Associated With Long-Term Intrathecal Clonidine Therapy

Abstract:   Intraspinal clonidine is an effective adjunct to intrathecal/epidural opioid administration. We report a case of neuropathic pain treated with intraspinal analgesics in which depression, insomnia, and night terrors developed in association with intraspinal clonidine.     

Multiple mechanisms govern the dynamics of depression at neocortical synapses of young rats

Synaptic transmission between pairs of excitatory neurones in layers V ( N = 38) or IV ( N = 6) of somatosensory cortex was examined in a parasagittal slice preparation obtained from young Wistar rats (14–18 days old). A combined experimental and theoretical approach reveals two characteristics of short-term synaptic depression. Firstly, as well as a release-dependent depression, there is a release-independent component that is evident in smaller postsynaptic responses even following failure to release transmitter. Secondly, recovery from depression is activity dependent and is faster at higher input frequencies. Frequency-dependent recovery is a Ca²⁺-dependent process and does not reflect an underlying augmentation. Frequency-dependent recovery and release-independent depression are correlated, such that at those connections with a large amount of release-independent depression, recovery from depression is faster. In addition, both are more pronounced in experiments performed at physiological temperatures. Simulations demonstrate that these homeostatic properties allow the transfer of rate information at all frequencies, essentially linearizing synaptic responses at high input frequencies.     

The Feasibility of Using Computrition Software for Nutrition Research—A Pilot Study

We evaluated the feasibility of using Computrition to design and implement a low vs. typical sodium meal plan intervention for older adults. Dietitians used Computrition to design a 7-day meal plan with three caloric levels (≤1750, 2000, ≥2250 kcals/day) and two sodium densities (low = 0.9 mg/kcal; n = 11 or typical = 2 mg/kcal; n = 9). Feasibility was determined by post-hoc definitions of effectiveness, sodium compliance, palatability of diet, sustainability, and safety. Given the low number of participants in one of the three calorie groups, the higher calorie groups were combined. Thus, comparisons are between low vs. typical meal plans at two calorie levels (≤1750 or ≥2000 kcals/day). Overall, regardless of the calorie group, the meal plans created with Computrition were effective in reaching the targeted sodium density and were safe for participants. Furthermore, individuals appeared to be equally compliant and reported similar palatability across meal plans. However, one of the three criteria for the sustainability definition was not met. In conclusion, we successfully used Computrition to design low and typical sodium meal plans that were effective, compliable, and safe. Future studies of older adults in similar settings should focus on improving the palatability of the meal plans and scaling this protocol to larger studies in older adults.     

考马斯亮蓝染色法检测人精子顶体反应的评价

为建立一种检测人精子顶体反应的简便实用的新技术，用３．５％高氯酸水溶液配制０．０５％考马斯亮蓝（Ｒ２５０）染色液浸染人精子３０ｍｉｎ，顶体完整者顶体区染成紫蓝色，顶体反应者则不染。对获能前后和钙离子载体Ａ２３１８７诱导顶体反应的精子进行染色并与经典的顶体反应检测技术ＰＳＡ法对照，两种方法检测顶体反应率无显著差异。方法学检验证明新技术结果可靠。本法操作简便、经济，普通显微镜即可检测，易于推广，克服了原有技术复杂昂贵的缺点，具有研究和临床诊断的良好价值。     

The histopathologic spectrum of decorative tattoo complications

Tattooing for ornamental purposes is an ancient practice that remains popular in modern times. Tattoos are encountered by the dermatopathologist either as incidental findings on skin biopsies or because of complications specific to the tattoo. A range of neoplasms and inflammatory conditions are seen in association with tattoos, many of which may be attributed to hypersensitivity to tattoo inks. The composition of tattoo inks is highly variable, and inks can contain numerous potentially allergenic or carcinogenic compounds. Infections with bacterial, viral and fungal species can occur after tattooing, sometimes after substantial delay. Atypical mycobacterial infections in particular are increasingly reported; special stains for mycobacteria should be performed and cultures recommended particularly when dense, mixed or granulomatous infiltrates are present.