Extracellular glucose concentrations in the rat hippocampus measured by zero-net-flux: effects of microdialysis flow rate, strain, and age

The concentration of glucose in the brain's extracellular fluid remains controversial, with recent estimates and measurements ranging from 0.35 to 3.3 mM. In the present experiments, we used the method of zeronet-flux microdialysis to determine glucose concentration in the hippocampal extracellular fluid of awake, freely moving rats. In addition, the point of zero-net-flux was measured across variations in flow rate to confirm that the results for glucose measurement were robust to such variations. In 3-month-old male Sprague-Dawley rats, the concentration of glucose in the hippocampal extracellular fluid was found to be 1.00 +/- 0.05 mM, which did not vary with changes in flow rate. Three-month-old and 24-month-old Fischer-344 rats both showed a significantly higher hippocampal extracellular fluid glucose concentration, at 1.24 +/- 0.07 and 1.21 +/- 0.04 mM, respectively; there was no significant difference between the two age groups. The present data demonstrate variation in extracellular brain glucose concentration between rat strains. When taken together with previous data showing a striatal extracellular glucose concentration on the order of 0.5 mM, the data also demonstrate variation in extracellular glucose between brain regions. Traditional models of brain glucose transport and distribution, in which extracellular concentration is assumed to be constant, may require revision.     

Serological responses in Lyme disease: the influence of sex, age, and environment

Social workers in a rehabilitation hospital established an outreach service through which volunteers with previous amputations visited patients with recent amputations, acting as role models and offering emotional support and information. Volunteers received in-depth training and continued with their own system of support. Patients who were visited had strong positive responses to the program. Critical components of the program were developing a collaborative partnership between volunteers and social workers; demonstrating credibility to health care professionals; linking emotional support, information, and affirmation; providing benefits to both patient and volunteer; and strengthening linkages among patient, community, and institution.     

Streets, drugs, and the economy of sex in the age of AIDS

Drug addicted women whose economic and social base is urban streets face limited options for income generation and multiple dangers of predation, assault, arrest, and illness. Exchanging sex for money or drugs offers one important source of income in this context. Yet the legal, social, and safety risks associated with these exchanges reduce the likelihood of regular safer sex practices during these encounters, thereby increasing the risk of HIV infection. Such conditions lead women engaged in sexual exchanges for money to varied and complex responses influenced by multiple and often contradictory pressures, both personal and contextual. Street-recruited women drug users in an AIDS prevention program in Hart-ford, Connecticut reported a range of condom use when engaging in sex for money exchanges. This paper explores their differences by ethnicity, economic resources, and drug use, and analyzes these and other factors that impact on street risks through sexual income generation. Surveys and in-depth interviews with drug-addicted women sex workers describe their various approaches to addressing multiple risks on the streets and suggest significant effort by women in these contexts to avoid the many risks, including HIV infection.     

Free radical theory of aging: effect of age, sex and dietary precursors on rat-brain docosahexanoic acid

Increasing the peroxidizability of dietary fat has an adverse effect on the function of the central nervous system (CNS) in the rat. This effect may be influenced by the level of docosahexanoic acid, a highly unsaturated fatty acid, selectively concentrated in the phospholipids of brain membranes. This study was aimed at determining the influence of age, sex, and the nature of a dietary lipid supplement - linolenic acid (18:3w3), docosahexanoic acid (22:6w3), or the same amount of 22:6w3 in the form of menhaden oil triglycerides - on the rate of increase in the percentage of 22:6w3 in the whole-brain fatty acids of rats between the ages of 1 and 12 months. The dietary lipid supplements were reflected in linear increases in the brain 22:6w3 of female rats throughout the study. Between 6 and 12 months of age, the rate of incorporation of dietary 22:6w3 and its precursors into the brain 22:6w3 of male rats dropped. At 12 months it was about half that for females in the case of 22:6w3 and menhaden oil, and about zero for 18:3w3. It is suggested that dietary 22:6w3 and its precursors may modify CNS function by altering membrane function and peroxidizability through changes in the concentration of 22:6w3 in membrane phospholipids.     

Relationship of age, age at onset, and sex to depression in older adults

The authors investigated the relationships among factors of age, age at onset, and sex in depressed older adults. A group of 96 outpatients (mean age, 60) diagnosed with late-(LOD) and early-onset (EOD) major depression were assessed for severity of depression and underwent magnetic resonance imaging (MRI). The MRI scans were rated for severity of white-matter hyperintensities (WMH) and ventricle-to-brain ratio (VBR). LOD was associated with increased amounts of WMH, larger VBR, and history of hypertension. Men were more severely depressed than women, with higher rates of neurovegetative signs and history of smoking. Age correlated with increased VBR and WMH, history of hypertension, history of percipitants for the current episode, and lack of social support. Results suggest that a subgroup of men may be more at risk for LOD associated with WMH and that sex and age at onset need to be considered in future studies.     

Hydroxysteroid sulfotransferase activity in the rat brain and liver as a function of age and sex

The high concentrations of dehydroepiandrosterone sulfate and pregnenolone sulfate in the mammalian brain, despite the blood-brain barrier's impermeability to these compounds, and the apparent independence of these concentrations from those in plasma prompted us to investigate whether enzymatic sulfation of dehydroepiandrosterone was detectable in the rat brain. Low hydroxysteroid sulfotransferase activities were detectable in in vitro incubations of homogenates from all rat brain regions except the cerebellum, being highest in the hypothalamus and pons. This activity was not ascribable to enzyme in brain capillary blood. The activity was mainly cytosolic, although there was also significant activity in the partially purified nuclear fraction. The enzyme had different properties from those of hepatic isozymes, with a pH optimum of 6.5 and a high Km of approximately 2 mM for dehydroepiandrosterone. The enzyme was also active with pregnenolone as substrate. Activities in the brain were approximately 300-fold lower than in the liver but, as in the liver, these were higher in females than in males. The variations in brain activity as a function of age did not parallel those in the liver. Relatively high activities were found in the fetal brain and declined at birth, while activities were insignificant in the fetal liver and rose following birth. There was a major peak in activity in pubertal female brains, but this peak was less important, and later, in males. No evidence was found to indicate that the low brain enzyme activities and high Km were attributable either to the presence of an inhibitor or to the steroid sulfation actually being a secondary activity of another brain sulfotransferase. We discuss whether the sulfotransferase activities found are adequate to synthesize the dehydroepiandrosterone and pregnenolone sulfate found in brain.     

Judgments of chronological age: Adult age and sex differences.

62 male and 137 female undergraduates and 76 male and 93 female Ss (mean age = 71.3 and 71.6 yrs, respectively) judged the ages of males and females portrayed in sets of 27 photographs. Results demonstrate the operation of judgmental assimilation and contrast principles in determinations of chronological age, with females exhibiting greater extremity of judgments than males. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tensile properties of human tendo Achillis: effect of donor age and strain rate

Two sets of tensile tests were conducted on tendo Achillis taken from 16 embalmed cadavers (donor ages, 36 to 100 years). From the stress, sigma-versus-strain, epsilon results, values of the following properties were obtained: linear stiffness, ST (which is defined as the slope of the linear zone of the post-toe region of the load-versus-extension plot), ultimate tensile strength [UTS], the strain at the UTS point (herein called the ultimate tensile strain) [epsilon max], and the tangent modulus of elasticity, [ET] (which is the slope of the linear zone of the post-toe region of the sigma-epsilon curve). In the first set of tests, the loading rate was 10%/sec. The results are thus: linear stiffness: 685 +/- 262 N/mm.; UTS = 59 +/- 18 MPa; epsilon max = 22 +/- 7%; and ET = 375 +/- 102 MPa. It was found that donor age exerts an insignificant effect on linear stiffness, a marked effect on UTS, an insignificant effect on epsilon max, and a moderate effect on ET (Student's t-test; p < 0.05). In the second set of tests, the test tendons were taken from the cadavers of "middle-aged" donors (52 to 67 years), and the strain rate was 100%/sec. By combining the results of the first and second sets of tests for a subset of this group (i.e., those with matched counterparts), it was found that strain rate has a statistically significant effect on ST and ET but not on UTS and epsilon max (paired Student's t-test; p < 0.05). Based on all results and findings, donor age is suggested as one of the considerations when selecting tendo Achillis to be used as allografts for the repair of severely damaged or ruptured tendo Achillis or anterior cruciate ligament.     

Voluntary alcohol consumption in vervet monkeys: individual, sex, and age differences

The patterns of voluntary alcohol consumption were studied in 35 vervet monkeys (Cercopithecus aethiops), classified into four groups. Each monkey showed a fairly steady rate during the studied period, resulting in individual differences that became more evident as the treatment evolved. Females showed higher alcohol intake frequencies than males. This sexual difference was maintained among adults and juveniles. Age differences were also observed: juveniles showed higher frequencies of intake than adults, both in general and in each sex group. Intake frequency was not related to age in prepubertal subjects, neither in general nor in each particular sex. The origin of these sex and age alcohol consumption differences remains to be studied, but differences in alcohol metabolism and factors related to puberty are possible influences.     

Illusory correlation in impression formation: Variations in the shared distinctiveness effect as a function of the distinctive person's age, race, and sex.

Examined in 3 parts with 96 White undergraduates, the nature of illusory correlation effects when associative connections and shared infrequency operated simultaneously. When undesirable behaviors were both infrequent and also associatively linked to a stimulus person's demographic group, there was an illusory correlation between membership in an infrequently appearing group and performance of infrequent, undesirable behaviors. More specifically, stimulus persons who were Black, old, or of the opposite sex from the S were rated more negatively when their demographic group appeared infrequently. Different illusory correlations were obtained when infrequency and associative links acted in opposition, undesirable behaviors being infrequent and desirable behaviors being associatively linked. More specifically, stimulus persons who were White, young, or of the same sex as the S were rated more positively when their demographic group appeared infrequently. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sensation seeking in England and America: Cross-cultural, age, and sex comparisons.

Compared the factor structure of the Sensation-Seeking Scale (SSS) in English and American samples, and constructed a new form of the SSS, applicable to both groups. The English Ss consisted of 254 males and 639 females from the Maudsley Twin Register, ages 15–70 yrs. The American sample included 97 male and female undergraduates. Three of the 4 factors showed good cross-national and cross-sex reliability (i.e., significant and reasonably high resemblance between the 4 national and sex symbols). English and American males did not differ on the total SSS score, but American females scored higher than English females. Males in both countries scored higher than females on the total SSS score and on the Thrill and Adventure-Seeking and Disinhibition subscales. Significant age declines occurred for both sexes, particularly on Thrill and Adventure Seeking and Disinhibition. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parenting during the second year: effects of children's age, sex, and attachment classification

70 2-parent families with 12-month-old infants and 67 2-parent families with 18-month-old toddlers participated in the study. Mothers and fathers participated in separate interviews and filled out questionnaires on family and child behaviors. Mothers and their children participated in the Ainsworth Strange Situation, and the families were observed for a total of 4 hours in their homes. Families were compared on composite measures of family environment variables, parents' perception of their children, and on process variables from home observations. Family differences in environmental stress and marital adjustment showed no effects for attachment classifications, although parents of 12-month-olds reported greater marital adjustment and more pleasure in parenting than parents of 18-months-olds. Both mothers and fathers reported that children classified as resistant were more difficult on several temperament measures. During home observations, 12-month-old children received more positive responses from mothers, and 18-month-old children received more instructions and directions from both parents. Insecure boys (both avoidant and resistant) received the least instructions and directions from both parents, but insecure-avoidant girls received the most instruction from fathers.     

Specific 3H-imipramine binding in human platelets. Influence of age and sex

Human platelets have been shown to possess high-affinity binding sites for 3H-imipramine. These binding sites have a similar affinity and drug specificity to those already described in rat brain. The platelets from healthy volunteers show no difference in 3H-imipramine binding between the sexes but there is a decrease in maximal 3H-imipramine binding with increasing age of the donor.     

Arcuate nucleus of the hypothalamus: effects of age and sex

Young children's attributions of gender-typed activities to figures/models differing in height and/or sex were examined over three experiments. The influence of gender constancy understanding on children's gender-typed attributions was also examined. In Experiment 1, young children attributed significantly more masculine activities to male than female figures and significantly more feminine activities to female than male figures. Experiment 2 confirmed the results demonstrated in Experiment 1. In Experiment 2, additional line-drawn stimuli and figure comparisons were incorporated; participants attributed significantly more masculine activities to taller than shorter male figures and taller than shorter female figures. In addition, children attributed significantly more feminine activities to taller than shorter female figures. In Experiment 3, participants viewed pictures of taller and shorter male and female models. Results confirmed those of Experiment 1, as well as most of those of Experiment 2. No consistent patterns of children's gender-typed attributions as a function of gender constancy understanding emerged in the three experiments. Results are discussed as they apply to unexplored tenets from Kohlberg's cognitive-developmental model, as well as those of gender schema models, of early gender role development.     

Locus of control: differences by sex and age

Fast x-ray computed tomography can be used to generate indicator dilution curves in perfused tissues following intravascular injection of roentgen contrast agent. These curves can be used to estimate regional parenchymal perfusion, intravascular blood volume, heterogeneity of these two parameters, and vascular bed transfer function.     

Sleep in relation to age, sex, and chronotype in Japanese workers

The Morningness-Eveningness Questionnaire and Life Habits Inventory were administered to 622 Japanese workers matched for sex and age. We investigated the distributions of the scores on the Morningness-Eveningness Questionnaire and sleep-wake habits by age and sex. Subjects were classified into five age groups and three chronotypes. The distributions and mean scores on the questionnaire advanced slightly toward the Morning type from the young to the aged group. The habitual bedtimes and waking times were significantly earlier in all the chronotypes from the young to the aged group, and the preferred bedtimes and waking times were also clearly earlier from the young to the aged group. The length of sleep was shorter for the Evening than the Morning types, especially in the group below 24 yr. The differences in habitual and preferred sleep length were greater than 1 hour for all age groups, especially the two groups under 34 yr. The number of awakenings during night sleep increased from the young to the aged group for all chronotypes. The older Evening type tended more toward frequent napping and longer naptime. The variabilities of bedtime and sleep length were larger for the young and Evening type than for the old group and Morning types. Further, the mood upon waking and satisfaction with sleep length were better in the aged Evening type than the young Morning type. The women under 44 yr. woke up earlier than the men of the same age, and the women of the 35-54 yr. groups had a shorter length of sleep than others. These may be related to childcare and housework. These results indicated that the phase of circadian rhythms had moved forward from the young to the aged group, and the individual's rhythm, of those that were aged Morning types, showed better agreement with sleep-wake rhythms than did others.     

Intima-media thickness and diameter of carotid and femoral arteries in children, adolescents and adults from the Stanislas cohort: effect of age, sex, anthropometry and blood pressure

OBJECTIVES: To study carotid and femoral intima-media thicknesses and diameters in relation to age, sex, morphologic status and blood pressure. PARTICIPANTS: The subjects were 369 men and women (aged 10-54 years) from the Stanislas cohort, with no known cardiovascular disease. METHODS: Intima-media thicknesses and diameters were measured by B-mode ultrasonography. The effects of sex, age, smoking, anthropometric variables, cholesterol and blood pressure were studied using bivariate and regression analysis. RESULTS: Carotid and femoral intima-media thicknesses were not affected by age nor by sex up to 18 years of age. Thereafter, they increased sharply in men and remained higher than in women. Values were correlated with systolic blood pressure only in men, and with fat-free mass in children and young adults only at the femoral site. Smoking, body mass index and fat mass were associated with intima-media thicknesses only in adults. Carotid diameter was little affected by age during childhood and in adults. Femoral diameter increased up to the age of 18 in both sexes and remained unaffected by age thereafter. This increase was more pronounced in boys, and so values became consistently greater in males aged over 14 years. Carotid diameter was correlated with body mass index or fat mass whereas femoral diameter was correlated with weight or fat-free-mass in children and men. The opposite was observed in women. CONCLUSION: Sex differences occur before adolescence for arterial diameter, but only at an adult age for intima-media thickness. In young subjects, carotid geometry seems to be influenced by blood pressure and excess body weight, while femoral artery geometry seems to be related to blood pressure and body growth.