Together Everyone Achieves More? Herding Behavior in the Finnish Stock Market

This thesis examines whether or not Finnish stock markets has herding behavior. Sample data is from 2004 to 2013. Including total of 2516 market days. Market wide herding, up and down market herding, extreme price movement herding and turnover volume herding are measured in this thesis. Methods used in this thesis are cross-sectional absolute dispersion and cross-sectional standard deviation. This thesis found no signs of herding in the Finnish stock market.

Pup age and aggressive behavior in lactating rats

High levels of aggressive behaviors against intruders in the nest area are displayed by female rats during the first 10 days after delivery, declining thereafter to very low levels, even though lactation continues. Cross-fostering experiments were undertaken to test the hypothesis that pup age may affect aggression in lactating rats. The behavior of females on the 8th day after delivery when raising fostered 8-day-old pups was compared to that of females on the 8th postpartum day raising older pups (18 days old) for the last 5 days, and females on the 18th day after delivery raising fostered 18-day-old pups were compared to females in the same postpartum period nursing younger pups (8 days of age at the time of the maternal aggression test) for 5 days. Pup retrieval activity and plasma prolactin level were also analyzed. Females on the 8th postpartum day nursing 18-day-old pups were less aggressive than females in the same postpartum period, but with 8-day-old pups. Likewise, females on the 18th postpartum day nursing younger pups were more aggressive and presented higher levels of prolactin than females nursing older pups. Thus, pup development can alter the natural decline of maternal aggressive behavior.

Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress

In order to investigate whether prolonged stress interferes with the onset of sexual behavior at puberty and with fertility at adulthood, prepubertal male Wistar rats (40 days of age) were immobilized 6 h a day for 15 days (up to early puberty) or for 60 days (until sexual maturity). Pubertal stressed rats showed a two-fold increase in the latency for the first mount (probably due to repeated aversive experience in which a change of environment was always followed by immobilization) and a 2.5-fold increase in the frequency of thrusting (indicative of enhanced sexual performance). The apparently stimulatory effect of prolonged stress on the onset of sexual behavior is discussed in terms of increased testosterone level and interference with the complex interchanges between the neurotransmitters/neuropeptides involved in the central control of male sexual activity. Adult stressed animals were mated with normal females, which became pregnant but exhibited a more than two-fold increase in both pre-implantation and post-implantation loss, probably due to a smaller rate of fertilization and/or fertilization with damaged spermatozoa.

Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses

This is a review of the research undertaken since 1971 on the behavior and physiological ecology of sloths. The animals exhibit numerous fascinating features. Sloth hair is extremely specialized for a wet tropical environment and contains symbiotic algae. Activity shows circadian and seasonal variation. Nutrients derived from the food, particularly in Bradypus, only barely match the requirements for energy expenditure. Sloths are hosts to a fascinating array of commensal and parasitic arthropods and are carriers of various arthropod-borne viruses. Sloths are known reservoirs of the flagellate protozoan which causes leishmaniasis in humans, and may also carry trypanosomes and the protozoan Pneumocystis carinii.

Effects of dietary lipids on renal function of aged rats

Normal aging is accompanied by renal functional and morphological deterioration and dietetic manipulation has been used to delay this age-related decline. We examined the effects of chronic administration of diets containing 5% lipid-enriched diet (LD, w/w) on renal function of rats at different ages. Three types of LD were tested: canola oil, fish oil and butter. Mean systemic tail-cuff blood pressure and glycemia remained within the normal range whatever the age and the diet of the animals. Proteinuria began to rise from the 8th month in the groups ingesting LD, while in the control group it increased significantly (above 10 mg/24 h) only after the 10th month. With age, a significant and progressive decline in glomerular filtration rate (GFR) and renal plasma flow was observed in the LD groups but after 6 months of lipid supplementation, the decline in these parameters was more marked in the butter and fish oil groups. By the 18th month, the lowest GFR level was observed in the group ingesting the butter diet (2.93 ± 0.22 vs 5.01 ± 0.21 ml min-1 kg-1 in control, P<0.05). Net acid excretion, evaluated in 9- and 18-month-old rats, was stimulated in the fish oil group when compared both to control and to the other two LD groups. These results suggest that even low levels of LD in a chronic nutritional regimen can modify the age-related changes in renal function and that the impact of different types of lipid-supplemented diets on renal function depends on the kind of lipid present in the diet.

Incorporation of dietary trans monounsaturated fatty acids into tissues of Walker 256 tumor-bearing rats

The correlation between dietary trans fatty acids and neoplasia was examined in the present study. Walker 256 tumor-bearing and control rats were fed a trans monounsaturated fatty acid (MUFA)-rich diet for 8 weeks and the incorporation of trans fatty acids by tumor tissue was examined. Also, the effect of tumor growth on trans fatty acid composition of plasma and liver, and the content of thiobarbituric acid-reactive substances (TBARS) was determined. Walker 256 tumor cells presented both trans and cis MUFAs given in the diet. The equivalent diet proportions were 0.66 for trans and 1.14 for cis. Taking into consideration the proportion of trans MUFAs in plasma (11.47%), the tumor incorporated these fatty acids in a more efficient manner (18.27%) than the liver (9.34%). Therefore, the dietary trans fatty acids present in the diet are actively incorporated by the tumor. Tumor growth itself caused marked changes in the proportion of polyunsaturated fatty acids in the plasma and liver but provoked only slight modifications in both trans and cis MUFAs. Tumor growth also reduced the unsaturation index in both plasma and liver, from 97.79 to 86.83 and from 77.51 to 69.64, respectively. This effect was partially related to an increase in the occurrence of the lipid oxidation/peroxidation process of TBARS content which was increased in both plasma (from 0.428 to 0.505) and liver (from 9.425 to 127.792) due to tumor growth.

Effect of dietary (n-3) highly unsaturated fatty acids on growth and survival of fat snook (Centropomus parallelus, Pisces: Centropomidae) larvae during first feeding

The effect of rotifers, Brachionus rotundiformis (S-type), fed three different diets: A (rotifer fed Nannochloropsis oculata), B (rotifer fed N. oculata and baker's yeast, 1:1), and C (rotifer fed N. oculata and baker's yeast, 1:1, and enriched with Selcoâ), was evaluated based on the survival, growth and swim bladder inflation rate of fat snook larvae. Rotifers of treatment A had higher levels (4.58 mg/g dry weight) of eicosapentaenoic acid (EPA) than B (1.81 mg/g dry weight), and similar levels (0.04 and 0.06 mg/g dry weight, respectively) of docosahexaenoic acid (DHA). Rotifers of treatment C had the highest levels of EPA (13.2 mg/g dry weight) and DHA (6.08 mg/g dry weight). Fat snook eggs were obtained by spawning induction with human chorionic gonadotropin. Thirty hours after hatching, 30 larvae/liter were stocked in black cylindric-conical tanks (36-liter capacity). After 14 days of culture, there were no significant differences among treatments. Mean standard length was 3.13 mm for treatment A, 3.17 mm for B, and 3.39 mm for C. Mean survival rates were very low (2.7% for treatment A, 2.3% for B, and 1.8% for C). Swim bladder inflation rates were 34.7% for treatment A, 27.1% for B, and 11.9% for C. The lack of differences in growth and survival among treatments showed that the improvement of the dietary value of rotifer may not have been sufficient to solve the problem of larval rearing. Some other factor, probably pertaining to the quality of the larvae, may have negatively influenced survival.

Dietary fiber intake, stool frequency and colonic transit time in chronic functional constipation in children

The objective of the present study was to evaluate associations between fiber intake, colonic transit time and stool frequency. Thirty-eight patients aged 4 to 14 years were submitted to alimentary evaluation and to measurement of colonic transit time. The median fiber intake of the total sample was age + 10.3 g/day. Only 18.4% of the subjects presented a daily dietary fiber intake below the levels recommended by the American Health Foundation. In this group, the median left colonic transit time was shorter than in the group with higher dietary fiber intake (11 vs 17 h, P = 0.067). The correlation between stool frequency and colonic transit time was negative and weak for left colon (r = -0.3, P = 0.04), and negative and moderate for rectosigmoid and total colon (r = -0.5, P<0.001 and r = -0.5, P<0.001, respectively). The stool frequency was lower in the group with slow transit time (0.8 vs 2.3 per week, P = 0.014). In conclusion, most patients with chronic functional constipation had adequate dietary fiber intake. The negative correlation between stool frequency and colonic transit time increased progressively from proximal segments to distal segments of the colon. Patients with normal and prolonged colonic transit time differ in terms of stool frequency.

The brain decade in debate: VIII. Peptide hormones and behavior: cholecystokinin and prolactin

This article is a transcription of an electronic symposium held on November 28, 2000 in which active researchers were invited by the Brazilian Society of Neuroscience and Behavior (SBNeC) to discuss the advances of the last decade in the peptide field with particular focus on central actions of prolactin and cholecystokinin. The comments in this symposium reflect the diversity of prolactin and cholecystokinin research and demonstrate how the field has matured. Since both peptides play a role in reproductive behaviors, particularly mother-infant interactions, this was the starting point of the discussion. Recent findings on the role of the receptor subtypes as well as interaction with other peptides in this context were also discussed. Another issue discussed was the possible role of these peptides in dopamine-mediated rewarding systems. Both prolactin and cholecystokinin are involved in mechanisms controlling food intake and somatic pain thresholds. The role of peripheral inputs through vagal afferents modulating behavior was stressed. The advent of knockout animals as potential generators of new knowledge in this field was also addressed. Finally, interactions with other neuropeptides and investigation of the role of these peptides in other fields such as immunology were mentioned. Knowledge about the central functions of prolactin and cholecystokinin has shown important advances. The role of these peptides in neurological and psychiatric syndromes such as anorexia, drug abuse and physiological disturbances that lead to a compromised maternal behavior seems relevant.

Dopaminergic modulation of grooming behavior in virgin and pregnant rats

Dopamine receptors are involved in the expression of grooming behavior. The pregnancy-induced increase in self-licking observed in rats is important for mammary gland development and lactation. This study focuses on the role of dopamine receptor subtypes in grooming behavior of virgin and pregnant female rats. General and mammary gland grooming were measured in virgin rats treated with 0.25 mg/kg of the D1-like agonist SKF-81297 and antagonist SKF-83566 and the D2-like agonist lisuride and antagonist sulpiride. The effects of 0.01 and 0.25 mg/kg doses of the same agonists and antagonists were evaluated in pregnant rats as well. In virgin animals both SKF-83566 and sulpiride treatments significantly reduced the time spent in general grooming, while none of the dopamine agonists was able to significantly change any parameter of general grooming. Time spent in grooming directed at the mammary glands was not affected significantly by any of the drug treatments in virgin rats. All drugs tested significantly decreased the frequency of and the time spent with general grooming, while SKF-81297 treatment alone did not significantly reduce the duration of mammary gland grooming in pregnant rats. These data show that in female rats the behavioral effects of D1-like and D2-like dopamine receptor stimulation and blockade differ according to physiological state. The results suggest that dopamine receptors may play specific roles modulating grooming behavior in pregnant rats. Since grooming of the mammary gland during pregnancy may influence lactation, this aspect is relevant for studies regarding the perinatal use of dopamine-related drugs.

Reproductive experience influences grooming behavior during pregnancy in rats

The pregnancy-induced increase in self-licking observed in rats is important for mammary gland development and lactation. Reproductive experience has epidemiologial implications such as a decrease in the incidence of mammary gland cancer in women and it also influences various behavioral, neurochemical and endocrine parameters. The aim of the present study was to investigate the influence of reproductive experience on grooming behavior patterns during pregnancy in rats. Self-grooming behavior was measured in age-matched virgin, primi- and multigravid (days 7, 8, 9, 19, and 20 of pregnancy) rats. General grooming (head, forelimbs and shoulders) was not significantly different among virgin, primi- and multigravid rats during pregnancy. Confirming previous work, pregnant rats spent significantly more time in specific grooming (mammary glands, nipple lines, genital and pelvic regions) than did virgin animals. In addition, self- licking of mammary glands was significantly increased in multi- as compared to primigravid rats on days 8, 9, 19 and 20 of pregnancy. The increase in mammary gland grooming observed in multigravid rats appears to be a consequence of previous reproductive experience. These data show that reproductive experience modulates mammary gland grooming during pregnancy, possibly contributing to successful reproduction.

Effect of dietary linoleic acid on the progression of chronic renal failure in rats

The role of linoleic acid in chronic renal failure (CRF) is controversial. In the present study 21 male Wistar rats submitted to 5/6 renal mass reduction (R) and 16 normal controls (C) were fed a supplement (S) or normal (N) linoleic acid diet for 60 days starting 10 days after CRF. As expected, serum creatinine, cholesterol and triglycerides (mean ± SEM) were higher in the CRF groups compared to the C groups (P<0.05). The RS group presented lower cholesterol (84 ± 4 vs 126 ± 13 mg%) and triglyceride (88 ± 9 vs 132 ± 19 mg%) levels compared to the RN group. Proteinuria and kidney weight did not differ between CRF groups. Glomerular area increased 78% in RS and 100% in RN compared to control rats. Glomerular sclerosis index tended to be lower in RS (27%) compared to RN (38%), tubulointerstitial damage was similar between CRF groups (RS = 1.91 ± 0.2 and RN = 2.14 ± 0.3), and mesangial fractional volume increased to the same extent in both CRF groups. The data suggest that a linoleic acid-enriched diet did not protect against the progression of CRF after 60 days.

Effects of septal cholinergic lesion on rat exploratory behavior in an open-field

The medial septum participates in the modulation of exploratory behavior triggered by novelty. Also, selective lesions of the cholinergic component of the septohippocampal system alter the habituation of rats to an elevated plus-maze without modifying anxiety indices. We investigated the effects of the intraseptal injection of the cholinergic immunotoxin 192 IgG-saporin (SAP) on the behavior of rats in an open-field. Thirty-nine male Wistar rats (weight: 194-230 g) were divided into three groups, non-injected controls and rats injected with either saline (0.5 µl) or SAP (237.5 ng/0.5 µl). Twelve days after surgery, the animals were placed in a square open-field (120 cm) and allowed to freely explore for 5 min. After the test, the rats were killed by decapitation and the septum, hippocampus and frontal cortex were removed and assayed for acetylcholinesterase activity. SAP increased acetylcholinesterase activity in the septum, hippocampus and frontal cortex and decreased the total distance run (9.15 ± 1.51 m) in comparison to controls (13.49 ± 0.91 m). The time spent in the center and at the periphery was not altered by SAP but the distance run was reduced during the first and second minutes (2.43 ± 0.36 and 1.75 ± 0.34 m) compared to controls (4.18 ± 0.26 and 3.14 ± 0.25 m). SAP-treated rats showed decreased but persistent exploration throughout the session. These results suggest that septohippocampal cholinergic mechanisms contribute to at least two critical processes, one related to the motivation to explore new environments and the other to the acquisition and storage of spatial information (i.e., spatial memory).

Dietary cellulose has no effect on the regeneration of hemoglobin in growing rats with iron deficiency anemia

The objective of the present study was to determine the effect of cellulose on intestinal iron absorption in rats during recovery from iron deficiency anemia. Twenty-one-day-old male Wistar-EPM rats were fed an iron-free ration for two weeks to induce anemia. At 5 weeks of age, the rats were divided into two groups (both groups receiving 35 mg of elemental iron per kg diet): cellulose group (N = 12), receiving a diet containing 100 g of cellulose/kg and control (N = 12), receiving a diet containing no cellulose. The fresh weight of the feces collected over a 3-day period between the 15th and 18th day of dietary treatment was 10.7 ± 3.5 g in the group receiving cellulose and 1.9 ± 1.2 g in the control group (P<0.001). Total food intake was higher in the cellulose group (343.4 ± 22.0 g) than in the control (322.1 ± 13.1 g, P = 0.009) during the 3 weeks of dietary treatment. No significant difference was observed in weight gain (cellulose group = 132.8 ± 19.2, control = 128.0 ± 16.3 g), hemoglobin increment (cellulose group = 8.0 ± 0.8, control = 8.0 ± 1.0 g/dl), hemoglobin level (cellulose group = 12.3 ± 1.2, control = 12.1 ± 1.3 g/dl) or in hepatic iron levels (cellulose group = 333.6 ± 112.4, control = 398.4 ± 168.0 µg/g dry tissue). We conclude that cellulose does not adversely affect the regeneration of hemoglobin, hepatic iron level or the growth of rats during recovery from iron deficiency anemia.

Dietary fiber, energy intake and nutritional status during the treatment of children with chronic constipation

The present prospective study was carried out to determine dietary fiber and energy intake and nutritional status of children during the treatment of chronic constipation. Twenty-five patients aged 2 to 12 years with chronic constipation were submitted to clinical evaluation, assessment of dietary patterns, and anthropometry before and after 45 and 90 days of treatment. The treatment of chronic constipation included rectal disimpaction, ingestion of mineral oil and diet therapy. The standardized diet prescribed consisted of regular food without a fiber supplement and met the nutrient requirements according to the recommended daily allowance. The fiber content was 9.0 to 11.9 g for patients aged less than 6 years and 12.0 to 18.0 g for patients older than 6 years. Sixteen patients completed the 90-day follow-up and all presented clinical improvement. The anthropometric variables did not change, except midarm circumference and triceps skinfold thickness which were significantly increased. Statistically significant increases were also found in percent calorie intake adequacy in terms of recommended daily allowance (55.5 to 76.5% on day 45 and to 68.5% on day 90; P = 0.047). Percent adequacy of minimum recommended daily intake of dietary fiber (age + 5 g) increased during treatment (from 46.8 to 52.8% on day 45 and to 56.3% on day 90; P = 0.009). Food and dietary fiber intake and triceps skinfold thickness increased during follow-up. We conclude that the therapeutic program provided a good clinical outcome.