The amygdala response to emotional stimuli: a comparison of faces and scenes

As a central fear processor of the brain, the amygdala initiates a cascade of critical physiological and behavioral responses. Neuroimaging studies have shown that the human amygdala responds not only to fearful and angry facial expressions but also to fearful and threatening scenes such as attacks, explosions, and mutilations. Given the relative importance of facial expressions in adaptive social behavior, we hypothesized that the human amygdala would exhibit a stronger response to angry and fearful facial expressions in comparison to other fearful and threatening stimuli. Twelve subjects completed two tasks while undergoing fMRI: matching angry or fearful facial expressions, and matching scenes depicting fearful or threatening situations derived from the International Affective Picture System (IAPS). While there was an amygdala response to both facial expressions and IAPS stimuli, direct comparison revealed that the amygdala response to facial expressions was significantly greater than that to IAPS stimuli. Autonomic reactivity, measured by skin conductance responses, was also greater to facial expressions. These results suggest that the human amygdala shows a stronger response to affective facial expressions than to scenes, a bias that should be considered in the design of experimental paradigms interested in probing amygdala function.     

Methicillin‐Resistant Staphylococcus aureus: An Emerging Pathogen of Pets in Egypt with a Public Health Burden

Community‐acquired methicillin‐resistant Staphylococcus aureus (CA‐MRSA) has emerged to be a pathogen of public health burden causing infections with significant concern. This study was conducted to investigate methicillin‐resistant Staphylococcus aureus (MRSA) infection in pet dogs and cats as an emerging zoonosis that could be disseminated in the community. A total of 184 (nasal, oral, ear and wound) swabs were collected from 70 pet dogs and 48 pet cats, whereas 50 nasal and oral swabs were collected from 28 apparently healthy companion persons in intimate contact with pets and without history of hospitalization. All samples were cultured for the isolation and identification of Staphylococcus aureus using selective media, biochemical and serological tests, while isolates were identified as MRSA after antimicrobial susceptibility testing and determination of the MIC. PCR was applied using specific primers to confirm MRSA. Three MRSA isolates have been recovered from two dogs of 70 (2.9%) and one isolate from 28 examined persons (3.6%), while none of the examined cats yielded MRSA. Furthermore, we found that two MRSA isolates recovered from one diseased dog seemed to be hospital‐associated methicillin‐resistant Staphylococcus aureus (HA‐MRSA), whereas the other dog isolate as well as the human isolate were considered as community‐acquired (CA‐MRSA). The occurrence of MRSA in apparently healthy and/or diseased pet dogs makes it an emerging veterinary pathogen which could be considered a public health burden if it is disseminated in our community outside hospitals.     

Adiposity Measurements by BMI,Skinfolds and Dual Energy X-Ray Absorptiometry in relation to Risk Markers for Cardiovascular Disease and Diabetes in Adult Males

Background. Choice of adiposity measure may be important in the evaluation of relationships between adiposity and risk markers for cardiovascular disease and diabetes. Aim. We explored the strengths of risk marker associations with BMI, a simple measure of adiposity, and with measures provided by skinfold thicknesses and dual energy X-ray absorptiometry (DXA). Subjects and Methods. We evaluated in three subgroups of white males (n = 156–349), participating in a health screening program, the strengths of relationship between measures of total and regional adiposity and risk markers relating to blood pressure, lipids and lipoproteins, insulin sensitivity, and subclinical inflammation. Results. Independent of age, smoking, alcohol intake, and exercise, the strongest correlations with adiposity measures were seen with serum triglyceride concentrations and indices of insulin sensitivity, with strengths of association showing little difference between BMI and skinfold and DXA measures of total and percent body fat (R = 0.20–0.46, P < 0.01). Significant but weaker associations with adiposity were seen for serum HDL cholesterol and only relatively inconsistent associations with adiposity for total and LDL cholesterol and indices of subclinical inflammation. Conclusions. BMI can account for variation in risk markers in white males as well as more sophisticated measures derived from skinfold thickness measurements or DXA scanning.     

Neural mechanisms of genetic risk for impulsivity and violence in humans

Neurobiological factors contributing to violence in humans remain poorly understood. One approach to this question is examining allelic variation in the X-linked monoamine oxidase A (MAOA) gene, previously associated with impulsive aggression in animals and humans. Here, we have studied the impact of a common functional polymorphism in MAOA on brain structure and function assessed with MRI in a large sample of healthy human volunteers. We show that the low expression variant, associated with increased risk of violent behavior, predicted pronounced limbic volume reductions and hyperresponsive amygdala during emotional arousal, with diminished reactivity of regulatory prefrontal regions, compared with the high expression allele. In men, the low expression allele is also associated with changes in orbitofrontal volume, amygdala and hippocampus hyperreactivity during aversive recall, and impaired cingulate activation during cognitive inhibition. Our data identify differences in limbic circuitry for emotion regulation and cognitive control that may be involved in the association of MAOA with impulsive aggression, suggest neural systems-level effects of X-inactivation in human brain, and point toward potential targets for a biological approach toward violence.     

High resolution spiral CT scan in the diagnosis of pseudoaneurysm of ascending aorta

Pseudoaneurysms of the ascending aorta are rare (<1%), and extremely rare from aortic vent site, but can be a lifethreatening complication. The basic methods of diagnosis are computed tomography scan and aortography. We report high resolution spiral CT may provide the best less invasive means in the diagnosis of the pseudoaneurysm of the ascending aorta originated from the aortic vent site.     

An Interaction of Oxytocin Receptors with Metabotropic Glutamate Receptors in Hypothalamic Astrocytes

Hypothalamic astrocytes play a critical role in the regulation and support of many different neuroendocrine events, and are affected by oestradiol. Both nuclear and membrane oestrogen receptors (ERs) are expressed in astrocytes. Upon oestradiol activation, membrane‐associated ER signals through the type 1a metabotropic glutamate receptor (mGluR1a) to induce an increase of free cytoplasmic calcium concentration ([Ca²⁺]_i). Because the expression of oxytocin receptors (OTRs) is modulated by oestradiol, we tested whether oestradiol also influences oxytocin signalling. Oxytocin at 1, 10, and 100 nm induced a [Ca²⁺]_i flux measured as a change in relative fluorescence [ΔF Ca²⁺ = 330 ± 17 relative fluorescent units (RFU), ΔF Ca²⁺ = 331 ± 22 RFU, and ΔF Ca²⁺ = 347 ± 13 RFU, respectively] in primary cultures of female post‐pubertal hypothalamic astrocytes. Interestingly, OTRs interacted with mGluRs. The mGluR1a antagonist, LY 367385 (20 nm ), blocked the oxytocin (1 nm )‐induced [Ca²⁺]_i flux (ΔF Ca²⁺ = 344 ± 19 versus 127 ± 11 RFU, P < 0.001). Conversely, the mGluR1a receptor agonist, (RS)‐3,5‐dihydroxyphenyl‐glycine (100 nm ), increased the oxytocin (1 nm )‐induced [Ca²⁺]_i response (ΔF Ca²⁺ = 670 ± 31 RFU) compared to either compound alone (P < 0.001). Because both oxytocin and oestradiol rapidly signal through the mGluR1a, we treated hypothalamic astrocytes sequentially with oxytocin and oestradiol to determine whether stimulation with one hormone affected the subsequent [Ca²⁺]_i response to the second hormone. Oestradiol treatment did not change the subsequent [Ca²⁺]_i flux to oxytocin (P > 0.05) and previous oxytocin exposure did not affect the [Ca²⁺]_i response to oestradiol (P > 0.05). Furthermore, simultaneous oestradiol and oxytocin stimulation failed to yield a synergistic [Ca²⁺]_i response. These results suggest that the OTR signals through the mGluR1a to release Ca²⁺ from intracellular stores and rapid, nongenomic oestradiol stimulation does not influence OTR signalling in astrocytes.     

Incomplete recovery of muscle cell function following partial but not complete ischemia

A simultaneous comparison of the effect of partial and total ischemia on skeletal muscle was made in dogs. The totally ischemic muscle had larger changes in adenosine triphosphate (ATP), creatine phosphate (CP), and cellular transmembrane potential difference (PD) during the 3-hour ischemic period than the partially ischemic muscle. Following recovery, all measured parameters in the totally ischemic muscle returned to normal, but paradoxically the PD in the partially ischemic muscle remained depressed despite the return to normal levels of ATP and CP. Contrary to the results in partially and totally ischemic brain tissue there was no evidence for higher levels of lactic acid in the partially ischemic muscle that could explain the persistent alteration in muscle cell function.