Predicting spike timing of neocortical pyramidal neurons by simple threshold models

Neurons generate spikes reliably with millisecond precision if driven by a fluctuating current--is it then possible to predict the spike timing knowing the input? We determined parameters of an adapting threshold model using data recorded in vitro from 24 layer 5 pyramidal neurons from rat somatosensory cortex, stimulated intracellularly by a fluctuating current simulating synaptic bombardment in vivo. The model generates output spikes whenever the membrane voltage (a filtered version of the input current) reaches a dynamic threshold. We find that for input currents with large fluctuation amplitude, up to 75% of the spike times can be predicted with a precision of +/-2 ms. Some of the intrinsic neuronal unreliability can be accounted for by a noisy threshold mechanism. Our results suggest that, under random current injection into the soma, (i) neuronal behavior in the subthreshold regime can be well approximated by a simple linear filter; and (ii) most of the nonlinearities are captured by a simple threshold process.

A simple presurgical necrotizing enterocolitis-mortality scoring system

OBJECTIVE: To assess the relationship between early laboratory parameters, disease severity, type of management (surgical or conservative) and outcome in necrotizing enterocolitis (NEC). STUDY DESIGN: Retrospective collection and analysis of data from infants treated in a single tertiary care center (1980 to 2002). Data were collected on disease severity (Bell stage), birth weight (BW), gestational age (GA) and pre-intervention laboratory parameters (leukocyte and platelet counts, hemoglobin, lactate, C-reactive protein). RESULTS: Data from 128 infants were sufficient for analysis. Factors significantly associated with survival were Bell stage (P<0.05), lactate (P<0.05), BW and GA (P<0.01, P<0.001, respectively). From receiver operating characteristics curves, the highest predictive value resulted from a score with 0 to 8 points combining BW, Bell stage, lactate and platelet count (P<0.001). At a cutoff level of 4.5 sensitivity and specificity for predicting survival were 0.71 and 0.72, respectively. CONCLUSION: Some single parameters were associated with poor outcome in NEC. Optimal risk stratification was achieved by combining several parameters in a score.

Intracavity Generation of Radially Polarized CO2 Laser Beams Based on a Simple Binary Dielectric Diffraction Grating

We present experimental results on the intracavity generation of radially polarized light by incorporation of a polarization-selective mirror in a CO2 -laser resonator. The selectivity is achieved with a simple binary dielectric diffraction grating etched in the backsurface of the mirror substrate. Very high polarization selectivity was achieved, and good agreement of simulation and experimental results is shown. The overall radial polarization purity of the generated laser beam was found to be higher than 90% .

[Implant-supported bridges in the edentulous jaw. Clinical aspects of a simple treatment concept]

Clinical aspects of a simple treatment concept with fixed prostheses in the edentulous jaw are described. Fixed implant-supported reconstructions in the edentulous jaw require multiple implants, are technically complex, aesthetically demanding and metal-ceramic solutions are expensive. Specific surgical techniques to enhance the hard and soft tissue conditions become often necessary. Thus the bar-supported overdenture may be preferred, because problems with aesthetics and alveolar ridge deficiencies can be solved more easily and the number of implants is reduced. Both, the "All-on-Four" technique and the "Procera implant bridge" are simple type of fixed prostheses, comparable to overdentures or complete dentures with regard to design and technology. They present a cost-effective alternative, with predictable aesthetics and optimum passive fit.

The Hayman technique: a simple method to treat postpartum haemorrhage

Of the several uterine compression sutures described in more recent years to treat postpartum haemorrhage (PPH), the Hayman suture offers the potential advantages that can be applied faster and easier, avoiding the performance of a lower segment hysterotomy when PPH follows a vaginal delivery. Data on efficacy and safety are limited, and long-term follow-up information are lacking. We report our experience with the Hayman suture in 11 consecutive women with massive PPH. Of these, ten were successfully treated without further interventions. One woman ultimately required a hysterectomy. Postoperative course was uncomplicated in all the cases. The median follow-up time was 11 months (range 1-19). One woman conceived spontaneously 10 months after the procedure. Our results suggest that the Hayman suture is an effective and safe treatment for PPH.

Little strokes fill big oaks: a simple in vivo stain of brain cells

High-resolution functional imaging of neural activity in vivo relies on appropriate labeling methods. In this issue of Neuron, Nagayama et al. introduce a simple procedure for staining subsets of neurons with organic calcium indicator dyes via local electroporation. Neuronal populations are sparsely labeled, preserving the ability to resolve calcium signals in dendrites and synaptic structures.

Endocrine symptom assessment in women with breast cancer: what a simple "yes" means

GOALS OF WORK: To investigate the self-reported symptoms related to endocrine therapy in women with early or advanced breast cancer and the impact of these symptoms on quality of life (QL) indicators. MATERIALS AND METHODS: Symptom occurrence was assessed by the Checklist for Patients on Endocrine Therapy (C-PET) and symptom intensity was assessed by linear analogue self-assessment (LASA) indicators. Patients also responded to global LASA indicators for physical well-being, mood, coping effort and treatment burden. Associations between symptoms and these indicators were analysed by linear regression models. MAIN RESULTS: Among 373 women, the distribution of symptom intensity showed considerable variation in patients reporting a symptom as present. Even though patients recorded a symptom as absent, some patients reported having experienced that symptom when responding to symptom intensity, as seen for decreased sex drive, tiredness and vaginal dryness. Six of 13 symptoms and lower age had a detrimental impact on the global indicators, particularly tiredness and irritability. CONCLUSIONS: Patients' experience of endocrine symptoms needs to be considered both in patient care and research, when interpreting the association between symptoms and QL.