A second protein-tyrosine kinase (PTK) of the focal adhesion kinase (FAK) subfamily, cell adhesion kinase ␤ (CAK␤), was identified by cDNA cloning. The rat CAK␤ is a 115.7-kDa PTK that contains N-and C-terminal domains of 418 and 330 amino acid residues besides the central kinase domain. The rat CAK␤ has a homology with mouse FAK over their entire lengths except for the extreme N-terminal 88 residues and shares 45% overall sequence identity (60% identical in the catalytic domain), which indicates that CAK␤ is a protein structurally related to but different from FAK. The CAK␤ gene is less evenly expressed in a variety of rat organs than the FAK gene. Anti-CAK␤ antibody immunoprecipitated a 113-kDa protein from rat brain, 3Y1 fibroblasts, and COS-7 cells transfected with CAK␤ cDNA. The tyrosinephosphorylated state of CAK␤ was not reduced on trypsinization, nor enhanced in response to plating 3Y1 cells onto fibronectin. CAK␤ localized to sites of cell-tocell contact in COS-7 transfected with CAK␤ cDNA, in which FAK was found at the bottom of the cells. Thus, CAK␤ is a PTK possibly participating in the signal transduction regulated by cell-to-cell contacts. Protein-tyrosine kinases (PTKs)1 that do not span the plasma membranes (so-called nonreceptor PTKs) have been classified into different subclasses (subfamilies) based on the sequence similarity and distinct structural characteristics (1). Many nonreceptor PTKs participate in cellular signal transduction by associating with the intracellular portions of transmembrane receptors which do not themselves have PTK activity. Different nonreceptor PTKs play diverse and specific roles in mediating the signal transduction by different nonkinase receptors (2-4).Focal adhesion kinase (FAK) has been proposed as the prototype (and hitherto the sole member) of a new subfamily of nonreceptor PTK, represented by proteins with large N-and C-terminal domains flanking the catalytic domain but without Src homology 2 and 3 (SH-2 and SH-3) domains (5-9). FAK is concentrated in focal adhesions (5, 6), and its phosphorylation and activation are triggered by the ligand binding to integrins and by the stimulation of certain growth factor and neuropeptide receptors (6, 10 -24). The N-and C-terminal domains of FAK mediate its interactions with integrins, the Src-family kinases and paxillin, a focal adhesion associated protein (8,9,(25)(26)(27)(28). By these and other yet to be characterized interactions, FAK regulates signaling via different receptors. Because only one member of the FAK subfamily is known to date, we sought to identify a second PTK of the FAK subfamily by a homologybased cDNA cloning strategy. We describe here an isolation and characterization of a cDNA coding for a new member of the FAK family. The novel PTK described here is the second member, to our knowledge, of the FAK subfamily whose cDNA has been cloned and sequenced and is designated CAK␤ for cell adhesion kinase ␤.

A physiologically motivated, dynamical model of cardiovascular autonomic regulation is shown to be capable of generating long-range correlated and multifractal heart rate. Virtual disease simulations are carried out systematically to account for the disease-induced relative dysfunction of the parasympathetic and the sympathetic branches of the autonomic control. Statistical agreement of the simulation results with those of real life data is reached, suggesting the possible use of the model as a state-of-the-art basis for further understanding of the physiological correlates of complex heart rate dynamics.

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Blind source separation is the computation underlying the cocktail party effect––a partygoer can distinguish a particular talker’s voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes’ principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico) demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle.

Rat superior cervical ganglion (SCG) neurons and ventricular myocytes (VMs) were co-cultured separately in a minichamber placed on a microelectrode-array (MEA) substrate. The minichamber, fabricated photolithographically using polydimethylsiloxane (PDMS), had 2 compartments, 16 microcompartments and 8 microconduits. The SCG neurons were seeded into one of the compartments and all of the microcompartments using a glass pipette controlled by a micromanipulator and a microinjector. The VMs were seeded into the other compartment. Three days after seeding of the VMs, the SCG neurons were still confined to one compartment and all of the microcompartments, and the neurites of the SCG neurons had connected with the VMs via the microconduits. Constant-voltage stimulation, using a train of biphasic square pulses (1 ms at +1 V, followed by -1 ms at 1 V), was applied to the SCG neurons in the microcompartments using 16 electrodes. Evoked responses were observed in several electrodes while electrical stimulation was applied to the SCG neurons. Two-way analysis of variance (ANOVA) revealed that the frequency of the stimulation pulses had significant effects in increasing the beat rate of the VMs, and that the interaction between the frequency and the number of the pulses also had a significant effect on the ratio. No significant increases in the beat rate were observed when propranolol, a β-adrenergic receptor antagonist, was added to the culture medium. These results suggest that synaptic pathways were formed between the SCG neurons and the VMs, and that this co-culture device can be utilized for studies of network-level interactions between sympathetic neurons and cardiomyocytes.