Adenosine, ‘pertussis-sensitive’ G-proteins, and K+ conductance in central mammalian neurones under energy deprivation

There is a striking similarity between the effects of adenosine and of hypoxia or glucose depletion on membrane potential and conductance of hippocampal neurones in tissue slices of rat brain. Both induce a membrane hyperpolarization by an increase in potassium conductance. It seemed likely, therefore, that a rise in extracellular adenosine concentration during energy deprivation may link neuronal metabolism with membrane K+ conductance. To test this hypothesis, we have now investigated the effects of hypoxia/glucose deprivation on hippocampal neurones from pertussis toxin-treated rats. In such slices adenosine had no effect on postsynaptic membrane potential and input resistance. Nevertheless, hypoxia or glucose depletion were as effective as in controls. These data provide evidence against adenosine as the main mediator between cell metabolism and potassium conductance

Preserving Family: Themes from a Qualitative Study of Kin Caregivers

This article presents themes from a qualitative study of 58 African American female kinship caregivers in San Francisco. Core concepts that emerged describe various paths along which children move into kin homes, and caregivers\u27 mixed emotional reactions to becoming surrogate parents. Women also discussed multiple family roles they assumed after taking in children. Responses highlight three primary reasons for becoming caregivers that center on providing for and protecting these children—particularly from the perceived threat of the public foster care system—and ultimately preserving the family unit. Paradoxically, caregivers\u27 reasons mirror the stated goals of the public foster care system, which they view as a threat to family stability. We discuss the problems of implementing practice and policy recommendations for permanency and family preservation and how to bridge the gap between the deeply held negative beliefs of African American caregivers towards the public system and begin to build trust

Identification of commonly expressed exoproteins and proteolytic cleavage events by proteomic mining of clinically relevant UK isolates of Staphylococcus aureus

The range of exoproteins and core exoproteome of 14 Staphylococcus aureus isolates representing major lineages associated with asymptomatic carriage and clinical disease in the UK was identified by MS proteomics using a combined database incorporating sequences derived from 39 S. aureus genomes. In all, 632 different proteins were identified and, of these, only 52 (8 %) were found in all 14 isolates whereas 144 (23 %) were found in just a single isolate. Comparison of the observed mass of each protein (based on migration by SDS-PAGE) with its predicted mass (based on amino acid sequence) suggested that 95 % of the proteins identified were not subject to any major post-translational modification. Migration of 5 % of the proteins was not as expected: 1 % of the proteins migrated at a mass greater than predicted, while 4 % appeared to have undergone proteolytic cleavage; these included SsaA2, Aur, SspP, Ebh as well as BlaR1, MecR1, FsH, OatA and LtaS. Intriguingly, a truncated SasG was produced by a single CC8 USA300-like strain. The analysis provided evidence of the marked heterogeneity in protein expression by S. aureus in broth, while yielding a core but narrow common exoproteome

Distribution of catecholamine fibers in the cochlear nucleus of horseshoe bats and mustache bats

The glyoxylic-acid-induced fluorescence technique was applied to demonstrate patterns of catecholaminergic innervation within the auditory brainstem of echolocating bats and the house mouse. In the cochlear nucleus of the rufous horseshoe bat (Rhinolophus rouxi) and the mustache bat (Pteronotus parnelli), species-specific catecholaminergic innervation patterns are found that contrast with the relatively homogeneous innervation in the rodent. In both bats the subnuclei of the cochlear nucleus receive a differentially dense supply of catecholaminergic fibers, and within the subnuclei, the catecholamine innervation densities can be correlated with the tonotopic frequency representation. The areas devoted to the high-frequency echolocation calls are less densely innervated than those regions which are responsive to lower frequencies. Apart from this common scheme, there are noteworthy distinctions between the two bats which correlate with specialized cytoarchitectural features of the cochlear nucleus. The marginal cell group, located medially to the anteroventral cochlear nucleus of Pteronotus, receives the densest supply of catecholaminergic fibers of all auditory nuclei. This plexus is formed by a morphologically distinct population of catecholaminergic fibers

Strict Liability for Prescription Drugs: Which Shall Govern-Comment K or Strict Liability Applicable to Ordinary Products?

This Comment will review the history of strict products liability and the policies which have shaped its development. It will examine the state of the law today regarding strict liability for harm caused by prescription drugs, and demonstrate that comment k should continue to govern prescription drugs. Furthermore, it will point out that sound reasoning and public policy dictate that the modified strict products liability of comment k, rather than ordinary strict products liability, is the appropriate theory to establish liability for prescription drugs; it is also the method most beneficial to society\u27s needs. Finally, this Comment will predict how the California Supreme Court will apply comment k to prescription drugs when the court is faced with the appropriate case

Interactions of a Dopamine D Receptor Agonist with Glutamate NMDA Receptor Antagonists on the Volitional Consumption of Ethanol by the mHEP Rat

Stimulation of the dopamine D1 receptor is reported to cause the phosphorylation of DARPP-32 at the thre34 position and activates the protein. If intracellular Ca2+ is increased, such as after activation of the glutamate NMDA receptor, calcineurin activity increases and the phosphates will be removed. This balance of phosphorylation control suggests that a D1 receptor agonist and a NMDA glutamate receptor antagonist should have additive or synergistic actions to increase activated DARPP-32 and consequent behavioral effects. This hypothesis was tested in a volitional consumption of ethanol model: the selectively bred Myers’ high ethanol preferring (mHEP) rat. A 3-day baseline period was followed by 3-days of twice daily injections of drug(s) or vehicle(s) and then a 3-day post-treatment period. Vehicle, the D1 agonist SKF 38393, the non-competitive NMDA receptor antagonist memantine, or their combination were injected 2 h before and after lights out. The combination of 5.0 mg/kg SKF 38393 with either 3.0 or 10 mg/kg memantine did not produce an additive or synergistic effect. For example, 5.0 mg/kg SKF reduced consumption of ethanol by 27.3% and 10 mg/kg memantine by 39.8%. When combined, consumption declined by 48.2% and the proportion of ethanol solution to total fluids consumed declined by 17%. However, the consumption of food also declined by 36.6%. The latter result indicates that this dose combination had a non-specific effect. The combination of SKF 38393 with (+)-MK-801, another NMDA receptor antagonist, also failed to show an additive effect. The lack of additivity and specificity suggests that the hypothesis may not be correct for this in vivo model. The interaction of these different receptor systems with intraneuronal signaling and behaviors needs to be studied further

Nonlinear self-action of light through biological suspensions

It is commonly thought that biological media cannot exhibit an appreciable nonlinear optical response. We demonstrate, for the first time to our knowledge, a tunable optical nonlinearity in suspensions of cyanobacteria that leads to robust propagation and strong self-action of a light beam. By deliberately altering the host environment of the marine bacteria, we show experimentally that nonlinear interaction can result in either deep penetration or enhanced scattering of light through the bacterial suspension, while the viability of the cells remains intact. A theoretical model is developed to show that a nonlocal nonlinearity mediated by optical forces (including both gradient and forward-scattering forces) acting on the bacteria explains our experimental observation

Corticotropin‐releasing hormone–induced seizures in infant rats originate in the amygdala

The neuroanatomical substrate of seizures induced by picomolar amounts of corticotropin‐releasing hormone in infant rats was investigated. Electrographic and behavioral phenomena were monitored in 42 rat pups aged 5 to 22 days. Rat pups carried bipolar electrodes implanted in subcortical limbic structures, as well as cortical electrodes and intracerebroventricular cannulae. The administration of corticotropin‐releasing hormone produced age‐specific seizures within minutes, which correlated with rhythmic amygdala discharges. Paroxysmal hippocampal and cortical discharges developed subsequently in some rats. Corticotropin‐releasing hormone–induced electrographic and behavioral seizures originate in the amygdala. Copyright © 1992 American Neurological Associatio