Inhibition of TrkB- and TrkC-Signaling Pathways Affects Neurogenesis in the Opossum Developing Neocortex.

We have previously reported that the blockage of TrkB and TrkC signaling in primary culture of opossum neocortical cells affects neurogenesis that involves a range of processes including cell proliferation, differentiation, and survival. Here, we studied whether TrkB and TrkC activity specifically affects various types of progenitor cell populations during neocortex formation in the Monodelphis opossum in vivo. We found that the inhibition of TrkB and TrkC activities affects the same proliferative cellular phenotype, but TrkC causes more pronounced changes in the rate of cell divisions. Additionally, inhibition of TrkB and TrkC does not affect apoptosis in vivo, which was found in cell culture experiments. The lack of TrkB and TrkC receptor activity caused the arrest of newly generated neurons; therefore, they could not penetrate the subplate zone. We suggest that at this time point in development, migration consists of 2 steps. During the initial step, neurons migrate and reach the base of the subplate, whereas during the next step the migration of neurons to their final position is regulated by TrkB or TrkC signaling.

Stability and consumer acceptance of long-chain omega-3 fatty acids (eicosapentaenoic acid, 20:5, n-3 and docosahexaenoic acid, 22:6, n-3) in cream-filled sandwich cookies.

We formulated a filling for sandwich cookies containing 400 mg of eicosapentaenoic acid, 20:5, n-3 (EPA) + docosahexaenoic acid, 22:6, n-3 (DHA) encapsulated in a matrix of starch and gelatin. Cookies were stored at 2 different temperatures (18 degrees C and 35 degrees C) and under 2 different packaging conditions (atmospheric and vacuum packed) for 28 d. At regular intervals, cookies were analyzed for moisture, water activity, and concentrations of EPA, DHA, and dienes. Results showed that there were no significant losses of EPA and DHA during storage under the conditions of study. A maximum loss of 5% was observed after 28 d of storage. The concentration of dienes obtained under different conditions were low (< 25 mmol/kg) as compared to a salmon oil sample with appreciable signs of oxidation (600 mmol/kg). Sensory evaluation of cookies by an untrained panel of healthy consumers and ulcerative colitis patients revealed no aftertaste and high acceptability of the cookies. Our results demonstrated that it is possible to make shelf-stable fortified foods with high levels of long-chain omega3FA.

Optimization of the skin multiple analyte profile bioanalytical method for determination of skin biomarkers from D-Squame tape samples.

BACKGROUND/PURPOSE: This work was performed to optimize extraction conditions for D-Squame tape skin samples for use in the skin multiple analyte profile (SkinMAP) method, a Linco Research Corporation bead-based assay for skin analytes. The experiments were designed to help identify sources of variability during extraction that may be amenable to further control. METHODS: Two experimental designs were used to study factors influencing the extraction of skin samples from D-Squame tapes. Visually healthy skin samples were obtained from both female and male adult volar forearms. Factors studied in two experiments included: four surfactant (SDS) levels (0.02-0.2%), two buffer types [Citrate-phosphate buffered saline at pH 5.5, phosphate-buffered saline (PBS) at pH 7.4], two buffer volumes (1.0, 1.5 mL), two propylene glycol (PG) levels (0.1%, 1.0%), two extraction temperatures (7-10 degrees C, 22-30+ degrees C), two extraction times (30, 60 min), and location in sonication bath (two vectors). The response biomarkers were cortisol, fibronectin, human serum albumin, involucrin, keratin-6 and keratins 1, 10. Skin sampling sites were also evaluated as sources of variation. RESULTS: There was no single set of extraction conditions in our experiments that maximized recovery of all the biomarkers. SDS level had the most consistently significant (P<0.05) and directional effects on biomarker recoveries. In general, higher SDS resulted in higher recovery of all biomarkers. There was less consistency and fewer significant results for the other extraction factors. CONCLUSIONS: These data enable us to better manage SkinMAP studies and interpret their results. The use of 1.5 mL PBS containing 0.2% SDS and 0.5% PG with 30 min sonication at low (near 4 degrees C) temperature is optimal for the quantitation of a range of SkinMAP analytes. In order to protect researchers from obtaining inflated false positive rates, it is crucial to design such studies and analyze the data using appropriate statistical methodology, especially for those studies involving only a small number of subjects.

Personality moderators of the relationship between abusive supervision and subordinates' resistance.

Results of a study using data collected at 2 points in time, separated by 6 months, suggested that subordinates resisted their supervisors' downward influence tactics with greater frequency when their supervisors were more abusive and that subordinates' personality moderated the effects of abusive supervision. The relationship between abusive supervision and subordinates' dysfunctional resistance was stronger among subordinates who were lower in conscientiousness than among subordinates who were higher in conscientiousness, but this effect emerged only for subordinates who were also lower in agreeableness. The relationship between abusive supervision and subordinates' constructive resistance was stronger among subordinates who were higher in conscientiousness than among subordinates who were lower in conscientiousness. The study's implications for theory and research are discussed.

Development of brief methods to classify individuals by PROP taster status.

The purpose of this study was to develop brief methods for classifying individuals by genetic taste sensitivity to 6-n-propylthiouracil (PROP). Two methods are described, which are modifications of a commonly used, suprathreshold procedure. Eighty-nine adult subjects rated the perceived intensity of solutions of 0.032, 0.32 and 3.2 mmol/l PROP and 0.01, 0.1, 1.0 mol/l sodium chloride (NaCl) (three-solution test), as well as solutions of 0.32 mmol/l PROP and 0.1 mol/l NaCl (one-solution test) using the Labeled Magnitude Scale (LMS). Subjects were classified as PROP nontasters (n=22), medium tasters (n=51) or supertasters (n=16) by the three-solution test. Taster status was independently determined by the one-solution test using numerical cutoff scores, which were determined by calculating the +/-95% confidence interval around the group means for PROP taste intensity. Supertasters gave PROP a rating of > or =51 ("very strong" on the LMS) and nontasters gave PROP a rating of < or =15.5 (approximately "moderate" on the LMS). Medium tasters fell between these two limits. Ninety-one percent of nontasters, 82% of medium tasters and 89% of supertasters were classified in a similar way by the two methods. Agreement between methods was high [coefficient of association (P)=0.74; P < or =.001]. These data suggest that three- and one-solution methods can reliably classify subjects by taste sensitivity to PROP and could provide valuable tools in population-based studies.

Justice, citizenship, and role definition effects.

A limitation of the organizational citizenship behavior (OCB) literature is that theory and empirical evidence suggest that some employees define OCBs as part of their job. A theoretical framework that addresses this problem is tested in this article. The framework focuses on 2 effects: a role enlargement effect (i.e., employees with more favorable attitudes define OCB as inrole behavior, which, in turn, results in greater citizenship) and a role discretion effect (i.e., the relationship between employees' attitudes and their citizenship will be stronger among employees who define OCB as extrarole behavior). In tests of this framework with 2 independent samples of supervisor-subordinate dyads, role definitions were found to moderate several relationships between procedural justice and OCB, providing support for the role discretion effect. Implications for OCB theory and research are discussed.

Sweet taste and intake of sweet foods in normal pregnancy and pregnancy complicated by gestational diabetes mellitus.

BACKGROUND: Dietary compliance in gestational diabetes mellitus (GDM) is poor. Changes in sweet taste perception might alter food preferences in GDM, making dietary compliance difficult to achieve. These indexes have never been studied in GDM. OBJECTIVES: This study documented changes in sweet taste perception and dietary intakes in pregnant women with and without GDM and determined whether these differences persisted postpartum. DESIGN: Subjects were 30 pregnant women without GDM, 25 pregnant women with recently diagnosed GDM, and 12 nonpregnant control subjects. Pregnant women were tested at 28-32 wk gestation and retested 12 wk postpartum. Subjects evaluated the taste of strawberry-flavored milks with different sucrose (0-10%) and fat (0-10%) contents and glucose solutions (10-160 mmol/L). RESULTS: Women with GDM showed no differences in liking for the milk samples across test sessions and their liking ratings were not significantly different from those of nonpregnant control subjects. Women without GDM liked the 10% sucrose-sweetened milk samples less during pregnancy than at 12 wk postpartum (P

PROP taster status is related to fat perception and preference.

Individuals who are sensitive to the bitter compound 6-n-propylthiouracil (PROP) are also more sensitive to selected bitter and sweet substances, to sharp foods and to the trigeminal irritant capsaicin. PROP tasters have a greater density of fungiform papillae, and it is speculated that they also have more trigeminal innervation. Since oral texture perception is also mediated, in part, by trigeminal fibers, it has been proposed that individual differences in fat perception might also be linked to PROP taster status and taste bud density. This work tests the hypothesis that individuals who are PROP tasters: (i) have a higher density of fungiform papillae; (ii) are more sensitive to capsaicin; and (iii) have increased ability to discriminate differences in fat content in salad dressing. Hedonic ratings for the salad dressing were also collected and related to the perceptual judgments. Individual subjects were classified as PROP nontasters, medium tasters or supertasters (n = 25/group) by comparing their psychophysical function for PROP to that of NaCl. Papillae densities (papillae/cm2) were significantly different among the three taster groups (p < 0.0001), and were highest among the supertasters. Both medium tasters and supertasters perceived more oral burn from capsaicin than did nontasters at concentrations of 50, 70 and 100 ppm (p < 0.0001). Medium tasters and supertasters could also discriminate differences in fat content between 40% fat and 10% fat salad dressings (p < 0.005), but the nontasters could not. Although medium and supertasters showed no preference for either dressing, the nontasters preferred the 40% fat sample. The reasons for these latter findings are unclear at present. These data support the hypothesis that fat perception and preference can be linked to genetic and anatomical differences between individuals.

Fat perception is related to PROP taster status.

Individuals who are sensitive to the bitter compounds phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) are also more sensitive to selected bitter and sweet substances, to sharp-tasting foods, and to the trigeminal irritant capsaicin. PTC/PROP tasters have a greater density of fungiform taste papillae and it is speculated that PTC/PROP tasters also have more trigeminal innervation. Because oral texture perception is also mediated, in part, by trigeminal fibers, it has been proposed that individual differences in fat perception might also be linked to PTC/PROP taster status and taste bud density. This work tests the hypothesis that individuals who are PROP tasters: 1. have a higher density of fungiform papillae; 2. are more sensitive to capsaicin; and 3. have increased ability to discriminate differences in fat content in salad dressing. Individual subjects were classified as PROP nontasters, medium tasters, or supertasters (n = 25 per group) by comparing their psychophysical function for PROP to that of NaCl. Papillae densities (papillae/cm2) were significantly different among the 3 taster groups (p < or = 0.0001), and were highest among the supertasters. Both medium tasters and supertasters perceived more oral burn from capsaicin than did nontasters at concentrations of 50, 70, and 100 ppm (p < or = 0.0001). Medium tasters and supertasters could also discriminate differences in fat content between 40% fat and 10% fat salad dressings (p < or = 0.005), but the nontasters could not. These data provide the first published evidence that fat perception can be linked to genetic and anatomical differences between individuals.

Diet and physical activity in restrained eaters.

Food choices, nutrient intakes, activity patterns and restrained eating scores were obtained from 249 normal-weight, young adults using self-reported questionnaires. Restrained eaters reported that they consumed more fat-free dairy products, fewer full-fat dairy products, fewer servings of fats and oils, less red meat and more fruits and vegetables than unrestrained eaters. In contrast to previous research, we found no overall difference in estimated daily energy intakes between restrained and unrestrained eaters, although there was a strong trend for restrained men to consume fewer calories per day. However, restrained eaters consumed less fat and more carbohydrate than unrestrained eaters. Restrained eaters in general were not more physically active than unrestrained eaters, but among the most active women, the restrained eaters were estimated to consume 13.3% less fat then the unrestrained eaters. This relationship was not observed in men. These data suggest that: (1) restrained eating influenced macronutrient composition in our respondents, but these effects were somewhat different in men and women; and (2) exercise played an important role in the dieting practices of restrained women but not restrained men. Examining only the food intakes of restrained women without considering their physical activity patterns may provide an incomplete picture of their dieting strategies.

Sweet taste and diet in type II diabetes.

The relationship between sweet taste function and dietary intake was studied in 21 patients with type II diabetes mellitus and 16 age-, weight-, and sex-matched controls. Subjects rated the sweetness intensity and pleasantness of a series of beverage samples sweetened with sucrose: 1.5-24%, fructose: 1-18%, or aspartame: 0.25-4%. They also kept 7-day food records. No group differences were found in sweet taste perception, pleasantness ratings, daily energy intakes, or macronutrient composition of the diets. However, subjects with diabetes consumed less sucrose but 3.5 times more alternative sweeteners than did controls. Peak pleasantness ratings for the beverage samples were positively correlated with dietary sweetness content in the subjects with diabetes but not the controls. These findings suggest that in diabetes, hedonic ratings for a sweetened beverage were related to dietary sweetness intake rather than changes in sweet taste perception.

Use of reduced-calorie/reduced-fat foods by young adults: influence of gender and restraint.

Reduced-calorie/reduced-fat (RC/RF) foods are widespread in the food supply, but there are few published data on who is using them and why. A total of 226 college men (n = 76) and women (n = 150) participated in a survey investigating the influence of gender and dietary restraint on eating habits, dieting and the use of 11 categories of RC/RF foods. Men did not differ from women in their overall use of RC/RF foods, although specific foods were consumed by a greater percentage of women. Restrained eating was strongly related to use of all the foods (p < or = 0.001). Women and those higher in restraint used the foods primarily for weight-control purposes, whereas men and those lower in restraint tended to use the foods for both weight control and other reasons. Women and those high in restraint were also more likely to have changed their eating habits to achieve weight loss and maintenance goals and to achieve a healthier lifestyle. In contrast, a greater percentage of men and those low in restraint wanted to achieve weight gain. These data suggest that RC/RF foods were popular among respondents in the study, but that the reasons for their use by restrained and unrestrained eaters might reflect gender differences in body weight and health concerns.

Reliability of the sensory responder classification to learned flavor cues: a test-retest study.

Previous work from this laboratory has examined the extent to which learned associations between the flavor of food and the caloric consequences of food ingestion influence daily energy intake in humans. We have consistently identified a subset of subjects, called sensory responders, whose intakes were strongly guided by flavor cues. Sensory responders were identified on the basis of post hoc examination of energy intake patterns. The purpose of this study was to confirm the reliability of this classification scheme using a test-retest paradigm. Eighteen normal-weight, free-living adults participated in the study. Subjects were first fed a high-calorie lunch with distinctive flavors for 5 consecutive days then a low-calorie lunch with different distinctive flavors for an additional 5 days. Following this training, the flavors in the lunches were covertly switched. Subjects whose intakes were influenced by the change in the flavor cues were classified as sensory responders and those whose intakes were not influenced by the switch in the flavor cues were classified as sensory nonresponders. Subjects then repeated the protocol. All subjects who were classified as sensory responders at the end of the first trial were similarly classified at the end of the second trial, indicating that their initial responses were reliable.

Effects of learned flavor cues on single meal and daily food intake in humans.

This study examined the effects of learned flavor cues on lunch-meal and daily food intake in 39, normal-weight, free-living adults. Subjects were fed distinctly flavored high-calorie (HC) and low-calorie (LC) milkshake preloads. Following the repeated flavor-calorie pairings, the flavors of the milkshakes were covertly switched. Twenty-three percent of the participants were classified as sensory responders. That is, their lunch intake reflected the anticipated caloric content of the preloads based on the sensory properties rather than the true energy value. Short-term sensory learning did not reliably alter 24-h energy intake in these subjects. The remaining subjects (i.e., sensory nonresponders) ignored the flavor cues and consumed the same size lunches across all phases of the study. Compensation for the preloads was examined during the training period (i.e., before the flavors were switched). Sensory responders accurately adjusted lunch intakes on the first day of exposure to both preloads, demonstrating unlearned compensation for energy density. Compensation continued to be accurate across training days for the HC (85%) but not the LC preload (65%). Sensory nonresponders did not compensate accurately for either of the preloads. Thus, sensory responders were initially more responsive to the caloric density of the preloads and continued to make accurate adjustments when the flavor cue matched the caloric load (i.e., during training) but were misled by the flavor cue when it did not match the caloric consequence (i.e., when the flavors were switched). Sensory nonresponders ignored the sensory cues and ate the same size lunches regardless of the caloric value of the preload.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of engineering controls in reducing occupational exposure to aerosolized pentamidine.

Aerosolized pentamidine administration may pose potential risks to health care workers exposed to fugitive drug and to infectious respiratory pathogens (eg, tuberculosis) generated by pentamidine-induced cough. Classic infection control methods may be applied to this problem, although the effectiveness of these measures in mitigating environmental pentamidine exposure is unknown. Lack of data fully characterizing pentamidine's mechanism of action or potential mutagenicity, carcinogenicity, or teratogenicity raises concern and suggests worker exposed and environmental contamination be minimized. We report herein on the efficacy of an aerosol containment hood in containing fugitive pentamidine aerosol during administration.

Dietary restraint and responsiveness to sensory-based food cues as measured by cephalic phase salivation and sensory specific satiety.

Responsiveness to sensory-based food cues was examined in restrained and unrestrained, normal-weight subjects identified with the Three-Factor Eating Questionnaire. Salivary flow rate was measured with no food present and while subjects viewed hot pizza. In the presence of food, restrained eaters had a mean salivary flow rate (0.388 g/min) greater than twice that of the unrestrained eaters (0.186 g/min). During sensory specific satiety testing, subjects tasted and rated the pleasantness of 9 foods, then received a meal of either cheese and crackers or cookies. Changes in pleasantness for the tasted foods were evaluated at 2, 20, and 40 min following the meal. Both restrained and unrestrained subjects displayed similar patterns of sensory specific satiety, i.e., the pleasantness foods which were eaten decreased relative to foods tasted but not eaten. These patterns were unaffected by the type of food consumed in the test meal. These data demonstrate that restrained eaters show moderately enhanced salivary responses but no changes in sensory-specific satiety to food stimuli, suggesting that heightened responsiveness to the sensory properties of foods may not be a generalized phenomenon in restrained eaters.