The impact of sex on brain responses to smoking cues: a perfusion fMRI study

Background

Anecdotal and clinical theories purport that females are more responsive to smoking cues, yet few objective, neurophysiological examinations of these theories have been conducted. The current study examines the impact of sex on brain responses to smoking cues.

Methods

Fifty-one (31 males) cigarette-dependent sated smokers underwent pseudo- continuous arterial spin-labeled perfusion functional magnetic resonance imaging during exposure to visual smoking cues and non-smoking cues. Brain responses to smoking cues relative to non-smoking cues were examined within males and females separately and then compared between males and females. Cigarettes smoked per day was included in analyses as a covariate.

Results

Both males and females showed increased responses to smoking cues compared to non-smoking cues with males exhibiting increased medial orbitofrontal cortex and ventral striatum/ventral pallidum responses, and females showing increased medial orbitofrontal cortex responses. Direct comparisons between male and female brain responses revealed that males showed greater bilateral hippocampal/amygdala activation to smoking cues relative to non-smoking cues.

Conclusions

Males and females exhibit similar responses to smoking cues relative to non-smoking cues in a priori reward-related regions; however, direct comparisons between sexes indicate that smoking cues evoke greater bilateral hippocampal/amygdalar activation among males. Given the current literature on sex differences in smoking cue neural activity is sparse and incomplete, these results contribute to our knowledge of the neurobiological underpinnings of drug cue reactivity.

     

Samuel Beckett's "Rockaby": dramatizing the plight of the solitary elderly at life's end

Irish playwright Samuel Beckett's spare, compact, and provocative play Rockaby (1981) is a study in old age, isolation, and disengagement from life. In it, an elderly woman rocks in a chair while the audience hears a distant voice remembering her lifelong search for human contact or communion. The play dramatizes the woman's intense physical and psychological isolation and the last sputterings of her impulse to narrate. Such radical isolation may be a necessary precondition for a person relinquishing the narrating that Beckett equates with being, and surrendering unto death. Despite its apparent simplicity, the play powerfully explores the nature of aging in contemporary society, quality-of-life issues for the frail, solitary elderly in our communities and health-care institutions, and how the elderly prepare for life's end in a death-denying culture. Rockaby is thus a text that can help clinicians and other caregivers appreciate the predicament of solitary elderly persons nearing life's end and better understand how we all must manage one day the lonely, self-abnegating yet also paradoxically self-assertive act of dying.     

Activated Cdc42-associated kinase 1 is a component of EGF receptor signaling complex and regulates EGF receptor degradation

Cdc42-associated tyrosine kinase 1 (ACK1) is a specific down-stream effector of Cdc42, a Rho family small G-protein. Previous studies have shown that ACK1 interacts with clathrin heavy chain and is involved in clathrin-coated vesicle endocytosis. Here we report that ACK1 interacted with epidermal growth factor receptor (EGFR) upon EGF stimulation via a region at carboxy terminus that is highly homologous to Gene-33/Mig-6/RALT. The interaction of ACK1 with EGFR was dependent on the kinase activity or tyrosine phosphorylation of EGFR. Immunofluorescent staining using anti-EGFR and GFP-ACK1 indicates that ACK1 was colocalized with EGFR on EEA-1 positive vesicles upon EGF stimulation. Suppression of the expression of ACK1 by ACK-RNAi inhibited ligand-induced degradation of EGFR upon EGF stimulation, suggesting that ACK1 plays an important role in regulation of EGFR degradation in cells. Furthermore, we identified ACK1 as an ubiquitin-binding protein. Through an ubiquitin-association (Uba) domain at the carboxy terminus, ACK1 binds to both poly- and mono-ubiquitin. Overexpression of the Uba domain-deletion mutant of ACK1 blocked the ligand-dependent degradation of EGFR, suggesting that ACK1 regulates EGFR degradation via its Uba domain. Taken together, our studies suggest that ACK1 senses signal of EGF and regulates ligand-induced degradation of EGFR.     

Nutrient Subsidies from Iteroparous Fish Migrations Can Enhance Stream Productivity

Migratory animals often transfer nutrients between ecosystems, enhancing productivity in the subsidized system. Most research on nutrient subsidies by migratory fishes has focused on Pacific salmon, whose semelparous life history is unusual among migratory fishes. To test whether iteroparous species can provide ecologically important nutrient inputs to stream ecosystems, we experimentally blocked the migration of suckers (Catostomidae) midway up an oligotrophic tributary of Lake Michigan. Comparing reaches upstream of the barrier to downstream reaches containing thousands of breeding fish, we found that suckers elevated phosphorus and nitrogen concentrations three- to five-fold. Algal accrual was doubled and caddisflies grew 12% larger in subsidized reaches relative to reference reaches. An enclosure experiment demonstrated that caddisflies with access to a fish carcass rapidly became enriched in ¹⁵N and ¹³C, and experimental carcass additions were rapidly colonized by high densities of caddisflies. However, under natural conditions below the experimental barrier, caddisflies became enriched in ¹⁵N but not ¹³C, indicating that fish-derived nutrients entered the stream food web primarily through indirect pathways rather than direct consumption of carcasses or gametes. At pupation, an average of 18% of caddisfly tissue N below the barrier was sucker-derived. In comparison to our focal stream, a reference stream with few suckers showed no seasonal or longitudinal patterns in nutrients and stable isotopes. These results demonstrate that iteroparous fish migrations can spur productivity via nutrient subsidies, despite low mortality rates. Thus, concerns about negative ecosystem-level consequences of blocking migrations of semelparous fishes are also applicable to iteroparous species when migrations are large.     

Low Message Sensation Health Promotion Videos Are Better Remembered and Activate Areas of the Brain Associated with Memory Encoding

Greater sensory stimulation in advertising has been postulated to facilitate attention and persuasion. For this reason, video ads promoting health behaviors are often designed to be high in “message sensation value” (MSV), a standardized measure of sensory intensity of the audiovisual and content features of an ad. However, our previous functional Magnetic Resonance Imaging (fMRI) study showed that low MSV ads were better remembered and produced more prefrontal and temporal and less occipital cortex activation, suggesting that high MSV may divert cognitive resources from processing ad content. The present study aimed to determine whether these findings from anti-smoking ads generalize to other public health topics, such as safe sex. Thirty-nine healthy adults viewed high- and low MSV ads promoting safer sex through condom use, during an fMRI session. Recognition memory of the ads was tested immediately and 3 weeks after the session. We found that low MSV condom ads were better remembered than the high MSV ads at both time points and replicated the fMRI patterns previously reported for the anti-smoking ads. Occipital and superior temporal activation was negatively related to the attitudes favoring condom use (see Condom Attitudes Scale, Methods and Materials section). Psychophysiological interaction (PPI) analysis of the relation between occipital and fronto-temporal (middle temporal and inferior frontal gyri) cortices revealed weaker negative interactions between occipital and fronto-temporal cortices during viewing of the low MSV that high MSV ads. These findings confirm that the low MSV video health messages are better remembered than the high MSV messages and that this effect generalizes across public health domains. The greater engagement of the prefrontal and fronto-temporal cortices by low MSV ads and the greater occipital activation by high MSV ads suggest that that the “attention-grabbing” high MSV format could impede the learning and retention of public health messages.     

A new catheter for tumor targeting with radioactive microspheres in representative hepatic artery systems. Part I: impact of catheter presence on local blood flow and microsphere delivery

Building on previous studies in which the transport and targeting of (90)Y microspheres for liver tumor treatment were numerically analyzed based on medical data sets, this two-part paper discusses the influence of an anchored, radially adjustable catheter on local blood flow and microsphere delivery in an idealized hepatic artery system (Part I). In Part II a patient-inspired case study with necessary conditions for optimal targeting of radioactive microspheres (i.e., yttrium 90) onto liver tumors is presented. A new concept of optimal catheter positioning is introduced for selective targeting of two daughter-vessel exits potentially connected to liver tumors. Assuming laminar flow in rigid blood vessels with an anchored catheter in three controlled positions, the transient three-dimensional (3D) transport phenomena were simulated employing user-enhanced engineering software. The catheter position as well as injection speed and delivery function may influence fluid flow and particle transport. Although the local influences of the catheter may not be negligible, unique cross-sectional particle release zones exist, with which selectively the new controlled targeting methodology would allow optimal microsphere delivery. The insight gained from this analysis paves the way for improved design and testing of a smart microcatheter (SMC) system as well as new investigations leading to even more successful treatment with (90)Y microspheres or combined internal radiation and chemotherapy.     

A ligand field chemistry of oxygen generation by the oxygen-evolving complex and synthetic active sites

Oxygen-oxygen bond formation and O2 generation occur from the S4 state of the oxygen-evolving complex (OEC). Several mechanistic possibilities have been proposed for water oxidation, depending on the formal oxidation state of the Mn atoms. All fall under two general classifications: the AB mechanism in which nucleophilic oxygen (base, B) attacks electrophilic oxygen (acid, A) of the Mn4Ca cluster or the RC mechanism in which radical-like oxygen species couple within OEC. The critical intermediate in either mechanism involves a metal oxo, though the nature of this oxo for AB and RC mechanisms is disparate. In the case of the AB mechanism, assembly of an even-electron count, high-valent metal-oxo proximate to a hydroxide is needed whereas, in an RC mechanism, two odd-electron count, high-valent metal oxos are required. Thus the two mechanisms give rise to very different design criteria for functional models of the OEC active site. This discussion presents the electron counts and ligand geometries that support metal oxos for AB and RC O-O bond-forming reactions. The construction of architectures that bring two oxygen functionalities together under the purview of the AB and RC scenarios are described.     

Formulation of filamentous fungi for bioremediation

Mycelia of Marasmiellus troyanus embedded in calcium alginate granules with corn cob grits as a nutritive amendment were viable after one year with refrigeration but inviable when stored at room temperature. With refrigeration, Phanerochaete chrysosporium mycelia and spores embedded in alginate were both viable after one year. At room temperature, spores encapsulated in alginate granules gave good viability while mycelial formulations did not. In all trials, corn cob grits was superior to saw dust for extending shelf life. Corn cob grits-amended granules of both species were able to germinate and grow in both uncontaminated soil and chemical waste-contaminated soil. © Rapid Science Ltd. 1998