SEARCH · PubMed Health

Results for “coupled patch model”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources

PubMed1996

Regulation of connexin-43, GFAP, and FGF-2 is not accompanied by changes in astroglial coupling in MPTP-lesioned, FGF-2-treated parkinsonian mice.

Basic fibroblast growth factor (bFGF; FGF-2) has potent trophic effects on developing and toxically impaired midbrain dopaminergic (DAergic) neurons which are crucially affected in Parkinson's disease. The trophic effects of FGF-2 are largely indirect, both in vitro and in vivo, and possibly involve intermediate actions of astrocytes and other glial cells. To further investigate the cellular and molecular mechanisms underlying the restorative actions of FGF-2, and to analyse in more detail the changes within astroglial cells in the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-lesioned striatum, we have studied striatal expression and regulation of connexin-43 (cx43), the principal gap junction protein of astroglial cells, along with the expression of glial fibrillary acidic protein (GFAP), FGF-2, and functional coupling. Our results show an immediate, yet transient increase in cx43 mRNA, and a sustained increase in FGF-2 mRNA, GFAP-positive cells, and cx43-immunoreactive punctata following the MPTP lesion, without any induction of functional coupling between astrocytes and other glial cells as revealed by dye coupling of patched cells. Unilateral administration of FGF-2 in a piece of gelfoam caused a further increase in cx43-positive punctata immediately adjacent to the implant, which was more pronounced than after application of a gelfoam containing the nontrophic control protein cytochrome C. These changes were parallelled by a small increase in cx43 protein determined by Western blot, but not by alterations in the coupling state of cells in the vicinity of the gelfoam implant. Although our data indicate that MPTP and exogenous FGF-2 may alter expression and protein levels of cx43, they do not support the notion that increases in cellular coupling may underly the trophic and widespread actions of FGF-2 in the MPTP-model of Parkinson's disease.

Animals↗

PubMed2003

Scale-dependence of resource-biodiversity relationships.

The functional relationship between resource availability and species richness is addressed at different spatial scales. We analyse the smaller, community, scale by using a multi-species contact process coupled to a heterogeneous landscape, i.e. a stochastic spatial model of individual behavior in a system with limited resources. Using percolation theory, the theory of competitive exclusion processes, and the results of Monte Carlo simulations we show that a unimodal resource-species relationship may be understood as a tradeoff between the availability and connectivity of resource patches. We then pose the question of how resource-species relationships may be scaled up to the larger, regional, level and discuss the theoretical basis for differences in behavior at different scales. Regional ecosystems are modeled as statistical aggregates of dynamically driven small-scale ecosystems. Observing a transition from a unimodal relationship at small scales to a monotonically increasing relationship at large scales is shown to be contingent on the presence of a resource-dependent species pool. Finally, we confirm our theoretical prediction of a transition via Monte Carlo simulations of regional landscapes and discuss the potential complicating effects of spatial correlations in the distribution of both resources and species.

Animals↗

PubMed1997

Heterogeneity of astrocyte resting membrane potentials and intercellular coupling revealed by whole-cell and gramicidin-perforated patch recordings from cultured neocortical and hippocampal slice astrocytes.

Astrocytes are thought to regulate the extracellular potassium concentration by mechanisms involving both voltage-dependent and transport-mediated ion fluxes combined with intercellular communication via gap junctions. Mechanisms regulating resting membrane potential (RMP) play a fundamental role in determining glial contribution to buffering of extracellular potassium and uptake of potentially toxic neurotransmitters. We have investigated the passive electrophysiological properties of cultured neocortical astrocytes and astrocytes recorded in hippocampal slices from 18-25 d postnatal rats. These experiments revealed a wide range of astrocyte RMPs that were independent of developmental factors, length of culturing, cellular morphology, the electrophysiological techniques used (whole-cell vs perforated recording), cell-specific expression of Na+/2HCO3- co-transporters, or voltage-dependent Na+ channels. Exposure of cultured astrocytes to differentiation-inducing factors (such as cAMP) or inhibition of proliferation (by serum deprivation) did not significantly influence RMP. Expression of ATP-sensitive potassium channels was absent in these glia; thus, K(ATP)-related mechanisms did not contribute to cell resting potential. In both cultured and slice astrocytes, spontaneous electrophysiological changes were commonly observed. These reversible events, which resulted in differential sensitivity to potassium channel blockers (cesium and barium) and sudden current-voltage profile changes, were attributable to dynamic changes in cell-to-cell coupling, as confirmed by recordings from isolated pairs of cells. We conclude that the heterogeneity of astrocytic RMP and intercellular coupling both in culture and in situ are intrinsic properties of glia that may contribute to transcellular transport of potassium. We propose a model in which spatial buffering may be facilitated by heterogeneous mechanisms controlling glial RMP in combination with dynamic changes in intercellular coupling.

ATP-Binding Cassette Transporters↗

PubMed1997

A surface potential change in the membranes of frog skeletal muscle is associated with excitation-contraction coupling.

1. Voltage changes and intramembrane charge movements in the transverse tubule membranes (T-system) of frog fast twitch muscle fibres were compared using the potentiometric dye WW-375 and a Vaseline-gap voltage clamp. As shown previously, the potentiometric dye reports a dynamic surface potential change that occurs on the myoplasmic face of the T-system membranes when the macroscopic potential applied across the surface membrane exceeds the mechanical threshold (about -60 mV). 2. The voltage dependence of the extra surface potential change and charge movement were found to be similar. Both activated with a sigmoid voltage dependence centred around -35 to -40 mV, and saturated at voltages above 0 mV. Both processes inactivated upon sustained depolarization, with a mid-point for inactivation of -40 mV. 3. Pharmacological agents which alter charge movement and excitation-contraction (E-C) coupling altered the non-linear surface potential change in a parallel manner. Perchlorate, which potentiates charge movement and E-C coupling, slowed the activation and deactivation of both charge movement and the non-linear surface potential change at voltages above -40 mV, and shifted the voltage dependence of both processes by 13 14 mV to more negative voltages. Dantrolene, which depresses charge movement and E-C coupling, shifted the voltage dependence of both processes to more positive voltages. Nifedipine, which suppresses charge movement and E-C coupling, reduced the magnitude of both charge movement and the non-linear surface potential change. 4. The non-linear surface potential change remained after the sarcoplasmic reticulum (SR) was depleted of Ca2+, suggesting that it is not a consequence of Ca2+ release. 5. These results suggest that the non-linear surface potential change is closely associated with movements of the voltage sensor (dihydropyridine (DHP) receptor) that control E-C coupling and/or signal transduction across the triadic junction. We propose that the movement of charged intramembrane domains of the DHP receptor which generate charge movement drive a subsequent movement of charged intracellular molecular domains that move within about 1 nm of the T-system membrane to generate a measurable change in surface charge. For example, the postulated mobile surface charges could be on an intracellular domain of the voltage sensor or closely associated protein, or could be a charged molecular domain of a protein that associates/dissociates with T-system membrane or DHP receptor during E-C coupling.

Animals↗

PubMed1996

Metapopulations and equilibrium stability: the effects of spatial structure.

Recently, there has been a great deal of interest in the dynamics of metapopulations, where a number of local populations are coupled via dispersal. The importance of movement for the persistence of an ensemble of locally unstable patches has been established in many studies. In this paper, we present analytical and simulation results concerning the effects of spatial structure on the equilibrium stability of individual populations. We conclude that for general single-species and two-species competition models, the introduction of the spatial dimension in a biologically sensible way has no effect on the overall stability properties. In host-parasitoid models, however, strong host or parasitoid over-dispersal may be destabilizing.

Animals↗

PubMed1997

Cytosolic Ca2+ and protein kinase Calpha couple cellular metabolism to membrane K+ permeability in a human biliary cell line.

Cholangiocytes represent an important target of injury during the ischemia and metabolic stress that accompanies liver preservation. Since K+ efflux serves to minimize injury during ATP depletion in certain other cell types, the purpose of these studies was to evaluate the effects of ATP depletion on plasma membrane K+ permeability of Mz-ChA-1 cells, a model human biliary cell line. Cells were exposed to dinitrophenol (50 microM) and 2-deoxyglucose (10 mM) as the standard model of metabolic injury. Whole-cell and single K+ channel currents were measured using patch clamp techniques; and intracellular [Ca2+] ([Ca2+]i) was estimated by calcium green-1 fluorescence. Metabolic stress increased [Ca2+]i, and stimulated translocation of the alpha isoform of protein kinase C (PKCalpha) from cytosolic to particulate cell fractions. The same maneuver increased membrane K+ permeability 40-70-fold as detected by (a) activation of K+selective whole cell currents of 2,176+/-218 pA (n = 34), and (b) opening of apamin-sensitive K+ channels with a unitary conductance of 17.0+/-0.2 pS. PKCalpha translocation and channel opening appear to be related since stress-induced K+ efflux is inhibited by chelation of cytosolic Ca2+, exposure to the PKC inhibitor chelerythrine (25 microM) and downregulation of PKC by phorbol esters. Moreover, K+ currents were activated by intracellular perfusion with recombinant PKCalpha in the absence of metabolic inhibitors. These findings indicate that in biliary cells apamin-sensitive K+ channels are functionally coupled to cell metabolism and suggest that cytosolic Ca2+ and PKCalpha are selectively involved in the response.

2,4-Dinitrophenol↗

PubMed2002

FTY720: targeting G-protein-coupled receptors for sphingosine 1-phosphate in transplantation and autoimmunity.

The novel immunomodulator FTY720 is remarkably effective in models of transplantation and autoimmunity. Recent data show that phosphorylated FTY720 is an agonist at four sphingosine 1-phosphate receptors. Stimulation of sphingosine 1-phosphate receptors leads to sequestration of lymphocytes in secondary lymphatic tissues and thus away from inflammatory lesions and graft sites.

Animals↗

PubMed2002

N-terminal tyrosine residues within the potassium channel Kir3 modulate GTPase activity of Galphai.

trkB activation results in tyrosine phosphorylation of N-terminal Kir3 residues, decreasing channel activation. To determine the mechanism of this effect, we reconstituted Kir3, trkB, and the mu opioid receptor in Xenopus oocytes. Activation of trkB by BDNF (brain-derived neurotrophic factor) accelerated Kir3 deactivation following termination of mu opioid receptor signaling. Similarly, overexpression of RGS4, a GTPase-activating protein (GAP), accelerated Kir3 deactivation. Blocking GTPase activity with GTPgammaS also prevented Kir3 deactivation, and the GTPgammaS effect was not reversed by BDNF treatment. These results suggest that BDNF treatment did not reduce Kir3 affinity for Gbetagamma but rather acted to accelerate GTPase activity, like RGS4. Tyrosine phosphatase inhibition by peroxyvanadate pretreatment reversibly mimicked the BDNF/trkB effect, indicating that tyrosine phosphorylation of Kir3 may have caused the GTPase acceleration. Tyrosine to phenylalanine substitution in the N-terminal domain of Kir3.4 blocked the BDNF effect, supporting the hypothesis that phosphorylation of these tyrosines was responsible. Like other GAPs, Kir3.4 contains a tyrosine-arginine-glutamine motif that is thought to function by interacting with G protein catalytic domains to facilitate GTP hydrolysis. These data suggest that the N-terminal tyrosine hydroxyls in Kir3 normally mask the GAP activity and that modification by phosphorylation or phenylalanine substitution reveals the GAP domain. Thus, BDNF activation of trkB could inhibit Kir3 by facilitating channel deactivation.

Amino Acid Motifs↗

PubMed2006

Gap-junctional single-channel permeability for fluorescent tracers in mammalian cell cultures.

We have developed a simple dye transfer method that allows quantification of the gap-junction permeability of small cultured cells. Fluorescent dyes (calcein and Lucifer yellow) were perfused into one cell of an isolated cell pair using a patch-type micropipette in the tight-seal whole cell configuration. Dye spreading into the neighboring cells was monitored using a low-light charge-coupled device camera. Permeation rates for calcein and Lucifer yellow were then estimated by fitting the time course of the fluorescence intensities in both cells. For curve fitting, we used a set of model equations derived from a compartment model of dye distribution. The permeation rates were correlated to the total ionic conductance of the gap junction measured immediately after the perfusion experiment. Assuming that dye permeation is through a unit-conductance channel, we were then able to calculate the single-channel permeance for each tracer dye. We have applied this technique to HeLa cells stably transfected with rat-Cx46 and Cx43, and to BICR/M1R(k) cells, a rat mammary tumor cell line that has very high dye coupling through endogenous Cx43 channels. Scatter plots of permeation rates versus junctional conductance did not show a strictly linear correlation of ionic versus dye permeance, as would have been expected for a simple pore. Instead, we found that the data scatter within a wide range of different single-channel permeances. In BICR/M1R(k) cells, the lower limiting single-channel permeance is 2.2 +/- 2.0 x 10(-12) mm3/s and the upper limit is 50 x 10(-12) mm3/s for calcein and 6.8 +/- 2.8 x 10(-12) mm3/s and 150 x 10(-12) mm3/s for Lucifer yellow, respectively. In HeLa-Cx43 transfectants we found 2.0 +/- 2.4 x 10(-12) mm3/s and 95 x 10(-12) mm3/s for calcein and 2.1 +/- 6.8 x 10(-12) mm3/s and 80 x 10(-12) mm3/s for Lucifer yellow, and in HeLa-Cx46 transfectants 1.7 +/- 0.3 x 10(-12) mm3/s and 120 x 10(-12) mm3/s for calcein and 1.3 +/- 1.1 x 10(-12) mm3/s and 34 x 10(-12) mm3/s for Lucifer yellow, respectively. This variability is most likely due to a yet unknown mechanism that differentially regulates single-channel permeability for larger molecules and for small inorganic ions.

Animals↗

PubMed1999

Voltage-insensitive gating after charge-neutralizing mutations in the S4 segment of Shaker channels.

Shaker channel mutants, in which the first (R362), second (R365), and fourth (R371) basic residues in the S4 segment have been neutralized, are found to pass potassium currents with voltage-insensitive kinetics when expressed in Xenopus oocytes. Single channel recordings clarify that these channels continue to open and close from -160 to +80 mV with a constant opening probability (Po). Although Po is low ( approximately 0.15) in these mutants, mean open time is voltage independent and similar to that of control Shaker channels. Additionally, these mutant channels retain characteristic Shaker channel selectivity, sensitivity to block by 4-aminopyridine, and are partially blocked by external Ca2+ ions at very negative potentials. Furthermore, mean open time is approximately doubled, in both mutant channels and control Shaker channels, when Rb+ is substituted for K+ as the permeant ion species. Such strong similarities between mutant channels and control Shaker channels suggests that the pore region has not been substantially altered by the S4 charge neutralizations. We conclude that single channel kinetics in these mutants may indicate how Shaker channels would behave in the absence of voltage sensor input. Thus, mean open times appear primarily determined by voltage-insensitive transitions close to the open state rather than by voltage sensor movement, even in control, voltage-sensitive Shaker channels. By contrast, the low and voltage-insensitive Po seen in these mutant channels suggests that important determinants of normal channel opening derive from electrostatic coupling between S4 charges and the pore domain.

Algorithms↗

PubMed1998

Extinction times and phase transitions for spatially structured closed epidemics.

This paper considers the time to extinction for a stochastic epidemic model of SEIR form without replacement of susceptibles. It first shows how previous rigorous results can be heuristically explained in terms of the more transparent dynamics of an approximating deterministic system. The model is then extended to include a host population structured into patches, with weak nearest-neighbour mixing of infection. It is shown, by considering the approximating deterministic system, that the expected time to extinction in a population of n + 1 patches each of size N is of the form a log N + bn, provided that N > Nc where Nc is a critical patch size below which transits are unlikely to occur. This corresponds to the simple decomposition of the time of an epidemic into the time it takes to spread through one patch plus the time it takes to transit to each of n successive patches. Expressions for this threshold and the coefficients of the time to extinction are given in terms of the transmission parameters of infection and the coupling strength between patches. These expressions are compared with numerical results using parameters relevant to a study of phocine distemper virus in North Sea seals, and the agreement is found to be good for large and small N. In the region when N approximately Nc, where transits may or may not occur, interesting transitional behaviour is seen, leading to a non-monotonicity of the extinction time as a function of N.

Animals↗

PubMed2005

Neuron-transistor coupling: interpretation of individual extracellular recorded signals.

The electrical coupling of randomly migrating neurons from rat explant brain-stem slice cultures to the gates of non-metallized field-effect transistors (FETs) has been investigated. The objective of our work is the precise interpretation of extracellular recorded signal shapes in comparison to the usual patch-clamp protocols to evaluate the possible use of the extracellular recording technique in electrophysiology. The neurons from our explant cultures exhibited strong voltage-gated potassium currents through the plasma membrane. With an improved noise level of the FET set-up, it was possible to record individual extracellular responses without any signal averaging. Cells were attached by patch-clamp pipettes in voltage-clamp mode and stimulated by voltage step pulses. The point contact model, which is the basic model used to describe electrical contact between cell and transistor, has been implemented in the electrical simulation program PSpice. Voltage and current recordings and compensation values from the patch-clamp measurement have been used as input data for the simulation circuit. Extracellular responses were identified as composed of capacitive current and active potassium current inputs into the adhesion region between the cell and transistor gate. We evaluated the extracellular signal shapes by comparing the capacitive and the slower potassium signal amplitudes. Differences in amplitudes were found, which were interpreted in previous work as enhanced conductance of the attached membrane compared to the average value of the cellular membrane. Our results suggest rather that additional effects like electrodiffusion, ion sensitivity of the sensors or more detailed electronic models for the small cleft between the cell and transistor should be included in the coupling model.

Action Potentials↗

PubMed2002

Using patterned substrates to promote mixing in microchannels.

Using a lattice Boltzmann model for fluid dynamics, we investigate the flow and phase behavior of a binary fluid moving over a patterned substrate within a microchannel. The binary fluid consists of two immiscible components, A and B, and this liquid is subjected to a Poiseuille flow. The substrate is decorated with a checkerboard pattern of A- and B-like patches. Through a coupling of hydrodynamics and thermodynamics, each component is driven to flow from the nonwettable domains to wettable regions. As a consequence, the A and B fluids undergo extensive mixing within the microchannels. We investigate how the degree of mixing depends on the size of the patches, the velocity of the imposed flow field, and the characteristics of the fluid. The results provide guidelines for creating localized "mixing stations" within microfluidic devices. The findings also reveal how a combination of imposed flow fields and surface patterning can be exploited to control the phase behavior of complex fluids.

Journal Article↗

PubMed2002

Importance of cutaneous cooling during photothermal epilation: theoretical and practical considerations.

BACKGROUND AND OBJECTIVES: Sapphire contact cooling is widely used to prevent non-specific epidermal injury from occurring during selective laser treatment of unwanted hair and vascular lesions. This small study was performed to examine the clinical response of the skin to 800-nm laser irradiation with varying extent of cutaneous sapphire contact cooling. Observed clinical responses are compared to those predicted by theoretical analysis in an attempt to construct a more complete picture of sapphire contact cooling and its role in preventing non-targeted tissue devitalization during laser treatment of the skin using a wavelength, pulse duration, and radiant exposure commonly used for laser hair removal. STUDY DESIGN/MATERIALS AND METHODS: Three subjects each received a total of three pulses of laser light (800 nm) of equal radiant exposure (60 J/cm(2)), pulse duration (30 msec), and spot size (9 mm x 9 mm), but with varying extent of cutaneous cooling. One site was pre-cooled and heat-sinked with a chilled (5 degrees C) sapphire window in contact with the skin; another site was heat-sinked only with a room-temperature (20 degrees C) sapphire window in contact with the skin; and a third site received no pre-cooling or heat-sinking. Each site was examined immediately after treatment and at intervals throughout a 3-month period. The thermal response of the tissue was calculated in each case using a Monte Carlo model for light transport in multi-layered tissues coupled with an axisymmetric finite-difference heat diffusion model. Thermal injury was modeled as a first-order kinetic rate process using an Arrhenius expression. RESULTS: In all three subjects, the sites that were pre-cooled and heat-sinked showed no evidence of epidermal or dermal devitalization. The three sites that were heat-sinked only had a few patches of perifollicular epidermal devitalization and subsequent desquamation without any permanent epidermal or dermal injury, as would be evidenced by pigmentary alteration or textural change. In each subject, the site that received no pre-cooling or heat-sinking sustained epidermal and dermal devitalization, appearing as ulceration and resulting in sustained erythema and textural alteration. Clinical responses predicted by theoretical analysis agree with the clinical observations and show that the dominant effect of sapphire contact cooling for pulse durations of 30 msec or less is the reduction of fluence within the epidermis resulting from index matching at the skin surface. CONCLUSIONS: The results of this small study suggest that by judiciously selecting the laser pulse duration and pre-cooling and heat-sinking the epidermis in a manner that provides index matching and compression of the skin, epidermal damage can be avoided while administering the highest, most effective radiant exposures.

Aluminum Oxide↗

PubMed1998

Intermediate conductances during deactivation of heteromultimeric Shaker potassium channels.

A previous study of the T442S mutant Shaker channel revealed activation-coupled subconductance levels that apparently represent kinetic intermediates in channel activation (Zheng, J., and F.J. Sigworth. 1997. J. Gen. Physiol. 110:101-117). We have now extended the study to heteromultimeric channels consisting of various numbers of mutant subunits as well as channels without mutant subunits, all in the background of a chimeric Shaker channel having increased conductance. It has been found that activation-coupled sublevels exist in all these channel types, and are traversed in at least 80% of all deactivation time courses. In symmetric K+ solutions, the currents in the two sublevels have a linear voltage dependence, being 23-44% and 54-70% of the fully open conductance. Sublevels in different channel types share similar voltage dependence of the mean lifetime and similar ion selectivity properties. However, the mean lifetime of each current level depends approximately geometrically on the number of mutant subunits in the channel, becoming shorter in channels having fewer mutant subunits. Each mutant subunit appears to stabilize all of the conducting states by approximately 0.5 kcal/mol. Consistent with previous results in the mutant channel, sublevels in channels with two or no mutant subunits also showed ion selectivities that differ from that of the fully open level, having relatively higher K+ than Rb+ conductances. A model is presented in which Shaker channels have two coupled activation gates, one associated with the selectivity filter and a second associated with the S6 helix bundle.

Animals↗

PubMed2000

Redox regulation of cardiac muscle calcium signaling.

Signal transduction for cardiac muscle contraction is regulated by the Ca2+-induced Ca2+-release mechanism. Redox reactions by biological oxidants and antioxidants have been shown to alter the kinetics of Ca2+-induced Ca2+ release. We postulate that altered kinetics of Ca2+-induced Ca2+ release may divert the contractile pool of Ca2+ to elicit excitation-transcription coupling. We provide evidence that redox reactions regulate excitation-transcription coupling by showing that membrane depolarization may activate the GATA4 transcription factor only when the cells are pretreated with hydrogen peroxide. Therefore, redox regulation of the ryanodine receptor may serve as a mechanism to determine whether the contractile pool of Ca2+ should signal gene transcription during excitation-contraction coupling.

Action Potentials↗

PubMed1999

Electrically excitable normal rat kidney fibroblasts: A new model system for cell-semiconductor hybrids.

In testing various designs of cell-semiconductor hybrids, the choice of a suitable type of electrically excitable cell is crucial. Here normal rat kidney (NRK) fibroblasts are presented as a cell line, easily maintained in culture, that may substitute for heart or nerve cells in many experiments. Like heart muscle cells, NRK fibroblasts form electrically coupled confluent cell layers, in which propagating action potentials are spontaneously generated. These, however, are not associated with mechanical disturbances. Here we compare heart muscle cells and NRK fibroblasts with respect to action potential waveform, morphology, and substrate adhesion profile, using the whole-cell variant of the patch-clamp technique, atomic force microscopy (AFM), and reflection interference contrast microscopy (RICM), respectively. Our results clearly demonstrate that NRK fibroblasts should provide a highly suitable test system for investigating the signal transfer between electrically excitable cells and extracellular detectors, available at a minimum cost and effort for the experimenters.

Action Potentials↗

PubMedDate not supplied

Two methods for recommending bat weights.

Baseball players swung very light and very heavy bats through our instrument and the speed of the bat was recorded. These data were used to make mathematical models for each person. Then these models were coupled with equations of physics for bat-ball collisions to compute the Ideal Bat Weight for each individual. However, these calculations required the use of a sophisticated instrument that is not conveniently available to most people. So, we tried to find items in our database that correlated with Ideal Bat Weight. However, because many cells in the database were empty, we could not use traditional statistical techniques or even neural networks. Therefore, three new methods were used to estimate the missing data: (i) a neural network was trained using subjects that had no empty cells, then that neural network was used to predict the missing data, (ii) the data patching facility of a commercial software package was used, and (iii) the empty cells were filled with random numbers. Then, using these fully populated databases, several simple models were derived for recommending bat weights.

Adolescent↗