Stimulus-elicited behavior in rapid eye movement sleep without atonia.

Alert wakefulness (W) and rapid eye movement sleep (REM) are remarkably similar on several measures of brain activity, but 2 differences in REM are reduced sensory responsiveness and atonia in postural muscles. Pontine tegmental lesions create REM without atonia (REM-A), releasing motor behavior. In 9 cats, we studied the acoustic startle reflex (ASR), orienting (OR), and ponto-geniculo-occipital waves (PGOE) elicited by tones during W, REM, REM-A, and non-REM (NREM). OR occurred in W and REM-A, being most complete in cats with the most elaborate spontaneous behavior. ASR occurred in W, NREM, and REM-A in lesioned cats. In normal cats, ASR rarely appeared in NREM and REM. PGOE had similar characteristics in both groups. The similarity of REM to W is particularly obvious when cats lack motoneuronal inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

PHYSICAL STRUCTURE OF THE PRIMARY FROTH FROM ATHABASCA OIL SAND EXTRACTION: CRYOGENIC SAMPLING AND MICROSCOPIC OBSERVATION OF PILOT PLANT FROTHS

Significant incentives remain for decreasing the mean solids and water content and their variability in combined extraction froth from Athabasaca oil sands, both in the hot water processes now commercially implemented, and in projected processes typically operating at lower temperatures. The oil sand can be conditioned in different ways to generate aerated bitumen droplets which can be recovered as a froth by flotation. The froth formation processes determine the quantities of entrained water and solids, and hence froth quality is related to the vertical progression of physical structures in the froth layer. A sampling method was developed to take frozen samples simultaneously from different depths in the froth layer, for the first time, and applied in pilot plant extractions of Athabasca oil sands, operating in either the commercial (Clark) or a development (OSLO) configuration at various temperatures. The patterns of froth structures were rather similar, with minor differences more related to the process temperature than to the oil sand conditioning procedure. The froth structure progressed from loosely packed aerated bitumen droplets at the bottom to bitumen-continuous at the top with an extensive water-continuous middle region containing distorted aerated bitumen droplets and comprising approximately 70% of the total froth depth. An abrupt phase inversion had been expected but was clearly absent. A key factor determining the froth quality appears to be the ability of the bitumen droplets to distort without coalescing, and so to pack more closely allowing continued drainage of the aqueous phase. Implications for froth quality improvement are discussed.     

Sexual differentiation of play behavior in the ferret.

Three experiments examined the endocrine mechanisms responsible for sex differences in prepubertal play behavior of ferrets. In Exp I, 6 gonadally intact adolescent males exhibited higher levels of "stand-over" behavior than 6 females did in tests between 63 and 123 days of age with gonadally intact female partners of the same age. In Exp II, with 69 Ss, those Ss exposed to androgen or to ovarian steroids over Days 5–20 of postnatal life subsequently exhibited significantly higher levels of stand-over behavior in tests with females than did control females gonadectomized on Day 5 and not given steroids. None of the Ss in Exp II exhibited levels of stand-over behavior comparable to those of the gonadally intact males in Exp I. In Exp III, with 36 Ss, males gonadectomized and implanted subcutaneously with testosterone capsules on Day 70 and tested with females at 84–96 days of age exhibited levels of stand-over behavior comparable to those observed in Exp I in gonadally intact males of the same age (Weeks 12–24). Males gonadectomized on Day 70 and given no hormone at testing exhibited significantly lower levels of this behavior. Significantly lower levels were also exhibited by males gonadectomized on Day 35 and females gonadectomized on Day 70, regardless of whether they were tested with testosterone present after Day 70. Sex differences in the expression of prepubertal play behavior of ferrets apparently result from differential exposure of males and females to androgen over an extended postnatal period. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prenatal and neonatal testosterone exposure interact to affect differentiation of sexual behavior and partner preference in female ferrets.

Implanting testosterone (T) subcutaneously over Postnatal Days 5–20 masculinized sexual behavior, reduced proceptive responsiveness, and shifted sexual preference more readily in male than in female ferrets gonadectomized on Day 5. This enhanced sensitivity of males to neonatal T was best duplicated in females exposed transplacentally to T over Embryonic Days (E) 27–39 (41-day gestation) and injected at birth with T (2.5 μg sc in oil:10% ethanol). Extended exposure of male ferrets to high levels of T, beginning shortly after the onset of testicular steroidogenesis (E25) and continuing for several hours after birth (E41) normally sensitizes their brains to the subsequent organizational effects on coital performance and sexual motivation of the relatively low levels of T that circulate in male ferrets during the first 3 postnatal weeks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Leptin is a physiologically important regulator of food intake

OBJECTIVE: These studies were designed to test the hypothesis that endogenous leptin, acting within the brain plays a physiologically important role in the control of food intake in lean rats. DESIGN: Antibodies directed against mouse leptin were raised in rabbits. The purified IgG fractions prepared from pre-immune and immune sera were injected into the right lateral ventricle of lean Sprague-Dawley rats and obese Zucker fatty fa/fa rats. Changes in food intake were measured over the following 20 h period. RESULTS: The anti-leptin antibodies recognized a major epitope in the C-terminal region of the leptin molecule. The antibodies bound both mouse and rat leptin with high affinity, but did not bind human leptin, or a selected range of other hormones and neurotransmitters known to affect food intake. In competition studies, the binding of mouse, but not human leptin to the human Ob-Rb receptor was prevented by the antibodies. This indicates that the antibodies can block the action of leptin by preventing its binding to the ob-Rb receptor. Injection of the anti-leptin antibodies into the brain of lean rats led to an increase in food intake during the first hour after injection which was not compensated during the following 19 h period. Injection of the anti-leptin antibodies did not affect food intake in Zucker fatty fa/fa rats which express an abnormal ob-Rb receptor. CONCLUSION: Endogenous leptin acting within the brain plays a physiologically important role in the control of food intake in lean rats.     

Rapid and precise scanning helium ion microscope milling of solid-state nanopores for biomolecule detection

We report the formation of solid-state nanopores using a scanning helium ion microscope. The fabrication process offers the advantage of high sample throughput along with fine control over nanopore dimensions, producing single pores with diameters below 4 nm. Electronic noise associated with ion transport through the resultant pores is found to be comparable with levels measured on devices made with the established technique of transmission electron microscope milling. We demonstrate the utility of our nanopores for biomolecular analysis by measuring the passage of double-strand DNA.     

Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers.

40 habitual, heavy coffee drinkers (aged 18–48 yrs; mean consumption of 5.7 cups/day) were deprived of their morning coffee for 1 experimental session and not deprived of the other. During each session, Ss consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. Caffeine continues to cause blood pressure increases with chronic, heavy consumption and these effects do not appear to habituate with regular use. Ss reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)