Extracting Wave Structure from Biological Data with Application to Responses in Turtle Visual Cortex

Waves have long been thought to be a fundamental mechanism for communicating information within a medium and are widely observed in biological systems. However, a quantitative analysis of biological waves is confounded by the variability and complexity of the response. This paper proposes a robust technique for extracting wave structure from experimental data by calculating "wave subspaces" from the KL decomposition of the data set. If a wave subspace contains a substantial portion of the data set energy during a particular time interval, one can deduce the structure of the wave and potentially isolate its information content. This paper uses the wave subspace technique to extract and compare wave structure in data from three different preparations of the turtle visual cortex. The paper demonstrates that wave subspace caricatures from the three cortical preparations have qualitative similarities. In the numerical model, where information about the underlying dynamics is available, wave subspace landmarks are related to activation and changes in behavior of other dynamic variables besides membrane potential.     

Model for Transition from Waves to Synchrony in the Olfactory Lobe of Limax

A biophysical model for the interactions between bursting (B) cells and nonbursting (NB) cells in the procerebral lobe of Limax is developed and tested. Phase-sensitivity of the NB cells is exhibited due to the strong inhibition from the rhythmically bursting B cells. Electrical and chemical junctions coupled with a parameter gradient lead to sustained periodic waves in the lobe. Excitatory interactions between the NB cells, which rarely fire, lead to stimulus evoked synchrony in the lobe oscillations. A novel calcium current is suggested to explain the effects of nitric oxide (NO) on the lobe. Gap junctions are shown both experimentally and through simulations to be required for the oscillating field potentials.     

Millimeter wave exposure reverses TPA suppression of gap junction intercellular communication in HaCaT human keratinocytes

The effect of 30.16 GHz millimeter wave (MMW) exposure at 1.0 and 3.5 mW/cm2 on gap junction intercellular communication (GJIC) was studied in cultured HaCaT keratinocytes, using the fluorescence recovery after photobleaching (FRAP) technique and laser confocal scanning microscopy to follow the intracellular movement of 5,6-carboxyfluorescein diacetate dye. While MMW exposure alone for 1 h at either 1.0 or 3.5 mW/cm2 did not affect GJIC, MMW exposure in combination with 5 ng/ml TPA treatment reversed TPA induced suppression of GJIC. Exposure at 1.0 mW/cm2 resulted in a partial reversal, and exposure at 3.5 mW/cm2 resulted in essentially full reversal of the TPA suppression.     

Single millimeter wave treatment does not impair gastrointestinal transit in mice

Millimeter wave treatment (MWT) is based on those biological effects that develop following skin exposure to low power electromagnetic waves. This method of treatment is in wide clinical use in several Eastern European countries for treatment of a variety of conditions, including pain syndromes. However, most treatment modes of MWT were developed empirically, and certain indications and contraindications for the use of MWT remain to be established. In our previous blind experiments we have shown that the hypoalgesic effect of MWT may be quantitatively evaluated, and most probably mediated by the neural system in general, and the system of endogenous opioids in particular. Taking in consideration a well-known ability of opioids to cause gastrointestinal disturbances, which could limit clinical application of MWT, the main aim of the present study was to investigate whether a single MWT, that can produce opioid-related hypoalgesia, may also retard gut transit and colorectal passage in mice. The charcoal meal test was used to quantitatively evaluate upper gastrointestinal transit, and the glass bead test was employed to examine colonic propulsion in mice. MWT was applied to the nose area of mice. The MWT characteristics were: frequency = 61.22 GHz; incident power density = 15 mW/cm(2); and duration = 15 min. The results obtained have shown that MWT does not significantly change small intestinal or colonic transit in mice, and thus suppression of gastrointestinal motility should not be a setback in the clinical use of MWT.     

Eukaryotic cell locomotion depends on the propagation of self-organized reaction-diffusion waves and oscillations of actin filament assembly

Actin filament (F-actin) assembly kinetics determines the locomotion and shape of crawling eukaryotic cells, but the nature of these kinetics and their determining reactions are unclear. Live BHK21 fibroblasts, mouse melanoma cells, and Dictyostelium amoebae, locomoting on glass and expressing Green Fluorescent Protein-actin fusion proteins, were examined by confocal microscopy. The cells demonstrated three-dimensional bands of F-actin, which propagated throughout the cytoplasm at rates usually ranging between 2 and 5 microm/min in each cell type and produced lamellipodia or pseudopodia at the cell boundary. F-actin's dynamic behavior and supramolecular spatial patterns resembled in detail self-organized chemical waves in dissipative, physico-chemical systems. On this basis, the present observations provide the first evidence of self-organized, and probably autocatalytic, chemical reaction-diffusion waves of reversible actin filament assembly in vertebrate cells and a comprehensive record of wave and locomotory dynamics in vegetative-stage Dictyostelium cells. The intensity and frequency of F-actin wavefronts determine locomotory cell projections and the rotating oscillatory waves, which structure the cell surface. F-actin assembly waves thus provide a fundamental, deterministic, and nonlinear mechanism of cell locomotion and shape, which complements mechanisms based exclusively on stochastic molecular reaction kinetics.     

Function of caveolae in Ca2+ entry and Ca2+-dependent signal transduction

The correct spatial and temporal control of Ca²⁺ signaling is essential for such cellular activities as fertilization, secretion, motility, and cell division. There has been a long-standing interest in the role of caveolae in regulating intracellular Ca²⁺ concentration. In this review we provide an updated view of how caveolae may regulate both Ca²⁺ entry into cells and Ca²⁺-dependent signal transduction     

A comparative analysis of heat waves and associated mortality in St. Louis, Missouri – 1980 and 1995

 This research investigates heat-related mortality during the 1980 and 1995 heat waves in St. Louis, Missouri. St. Louis has a long history of extreme summer weather, and heat-related mortality is a public health concern. Heat waves are defined as days with apparent temperatures exceeding 40.6°C (105°F). The study uses a multivariate analysis to investigate the relationship between mortality and heat wave intensity, duration, and timing within the summer season. The heat wave of 1980 was more severe and had higher associated mortality than that of 1995. To learn if changing population characteristics, in addition to weather conditions, contributed to this difference, changes in population vulnerability between 1980 and 1995 are evaluated under simulated heat wave conditions. The findings show that St. Louis remains at risk of heat wave mortality. In addition, there is evidence that vulnerability has increased despite increased air-conditioning penetration and public health interventions. Received: 12 August 1997 / Revised: 12 January 1998 / Accepted: 13 February 1998     

Differential Modulation of SERCA2 Isoforms by Calreticulin

In Xenopus laevis oocytes, overexpression of calreticulin suppresses inositol 1,4,5-trisphosphate-induced Ca²⁺ oscillations in a manner consistent with inhibition of Ca²⁺ uptake into the endoplasmic reticulum. Here we report that the alternatively spliced isoforms of the sarcoendoplasmic reticulum Ca²⁺-ATPase (SERCA)2 gene display differential Ca²⁺ wave properties and sensitivity to modulation by calreticulin. We demonstrate by glucosidase inhibition and site-directed mutagenesis that a putative glycosylated residue (N1036) in SERCA2b is critical in determining both the selective targeting of calreticulin to SERCA2b and isoform functional differences. Calreticulin belongs to a novel class of lectin ER chaperones that modulate immature protein folding. In addition to this role, we suggest that these chaperones dynamically modulate the conformation of mature glycoproteins, thereby affecting their function.     

Variation of the phytoplankton community across the subtropical convergence zone in the west pacific sector of the southern ocean during early austral Summer 1995/6

Phytoplankton of the Southern Ocean, 140–148°E and 40–53°S, was sampled from early austral summer Nov. 1995 to Dec. 1995 to examine cell abundance, cell volume and biomass (cell carbon) distribution across the fronts. A total of 90 phytoplankton taxa were identified. They were 50 diatoms, 37 dinoflagellates, 2 silicoflagellates, and 1 prymnesiophyte. 73 species were observed from north of the subtropical convergence zone and 71 species from south of the subtropical convergence zone.Pseudonitzschia spp. was the most widely distributed species. Nanoplankton predominated cell number of phytoplankton throughout the stations. The abundance of diatoms was higher than that of dinofiagellates. Total biomass profiles were dependent to microphytoplankton biomass. Maximum cell number and biomass were observed from subsurface layer. Phytoplankton community changed across the subtropical convergence zone and 50–53°S (antarctic convergence zone), and physicoehemical factors seem to controll the distribution.     

Real‐time monitoring of incision profile during laser surgery using shock wave detection

Lack of sensory feedback during laser surgery prevents surgeons from discerning the exact location of the incision, which increases duration and complexity of the treatment. In this study we demonstrate a new method for monitoring of laser ablation procedures. Real‐time tracking of the exact three dimensional (3D) lesion profile is accomplished by detection of shock waves emanating from the ablation spot and subsequent reconstruction of the incision location using time‐of‐flight data obtained from multiple acoustic detectors. Here, incisions of up to 9 mm in depth, created by pulsed laser ablation of fresh bovine tissue samples, were successfully monitored in real time. It was further observed that, by utilizing as little as 12 detection elements, the incision profile can be characterized with accuracy below 0.5 mm in all three dimensions and in good agreement with histological examinations. The proposed method holds therefore promise for delivering high precision real‐time feedback during laser surgeries. (© 2013 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)