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We describe how hookworms interact with their human hosts by comparing lymphocyte phenotyping, proliferative responses, and cytokine and chemokine secretion patterns in adults who are either mono-infected with Necator americanus or egg-negative controls resident in an area of high transmission in Brazil. Cellular immune responses against crude hookworm antigen extracts from different developmental stages were evaluated simultaneously. Principal component analysis (PCA) was used to reduce the standardized immune responses. Random effects multivariate regression was then used to investigate whether principal components (PC) differ between the two groups once potential confounders and effect modifiers have been accounted for. Although hookworm patients had reduced percentages of T and B cells, they had higher levels of activated CD4(+) T and CD19(+) B cells. This state of 'immune activation' coincided with lower proliferative responses, especially to third-stage larval antigen. Cytokine levels in mono-infected adults were also lower and characterized by a mixed Th1/Th2-type profile. Excretory/secretory antigen from adult worms was a potent modulator of the immune response, resulting in diminished TNF-alpha and IL-10 secretion in peripheral blood mononuclear cells (PBMC) from hookworm infected patients. We propose that the longevity of hookworms in their human hosts results from a stage-specific, down-modulation of the immune response.

Assuntos

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Synthetic A-type carbonated apatite prepared in controlled conditions was irradiated at room temperature with 60Co gamma rays. The ESR spectrum was associated to axial CO2- and orthorhombic CO3- species. Radicals used as dose markers in biological apatites are long-lived paramagnetic species. The stability of the post-irradiation signal of A-type apatite was investigated for almost 2 years. Measurements showed variations in the spectra attributed to unstable CO3- species, which can be eliminated by thermal treatments at 100 degrees C for 24 h. Results indicated the potential use of an A-type carbonated apatite as a dosemeter.

Assuntos

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Selection of food can be affected by several factors, and with the method of self-selection, qualitative changes in nutritional balance may be detected. The goal of the present study was to evaluate feeding preferences in weaning rats using three macronutrients (protein, carbohydrate, and fat), through a free-choice method, evaluating the alteration in their feeding patterns as compared with the previous nutritional status during the early lactation period. We analyzed the effects of protein restriction during lactation over the nitrogen balance after the weaning. The dams were assigned to one of two diet conditions (nourished or malnourished). At weaning, two pups from each litter were housed individually in metabolic cages, and they were maintained on self-selection under a free-choice paradigm and were provided with separate sources of macronutrients. The parameter for evaluating the nutritional effectiveness of the diets was nitrogen balance. We observed that protein intake tended to increase and consumption of carbohydrate and fat tended to decrease progressively during the 3 wk of experiment. In selecting their own food, growing rats and malnourished rats consumed a larger amount of protein than the other rats. Nourished rats selecting their diet had a larger nitrogen balance than nourished rats receiving a composed diet; no nitrogen balance difference was found between the self-selecting groups. Rats can choose an adaptive form when recovering from protein malnutrition.

Assuntos

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It has been shown that environmental stimulation may reduce the damage caused by malnutrition to morphological and behavioural parameters; however, there are no data on the effects of stimulation on the Brainstem Auditory Evoked Potentials (BAEPs). The aim of this study was to evaluate the effects of protein malnutrition, nutritional recovery and environmental stimulation on the BAEPs of the rat. On the first day of life, the animals were divided into Well-nourished (W) and Malnourished (M) groups. At weaning, half the M rats were submitted to nutritional recovery (R) until the test day. All groups were subdivided into Stimulated (S) and Non-Stimulated (N) rats. BAEPs was tested in animals exposed to clicks of 90, 80 and 70 dB of intensity. The BAEPs latencies of waves I, II, III and IV in the left ear were analysed in independent groups of rats on the 14th, 18th, 22nd, 32nd, and 42nd days of age. Statistical analysis showed diet and environmental stimulation interaction on the latencies of waves I, II, III and IV at all tested ages. WN rats showed longer latencies of waves I, II, III and IV than WS rats, and MN rats also showed longer latencies of these waves compared to WN, MS and RN at all tested ages. The results showed that malnutrition caused a delay in the latency of all BAEPs waves in rats of all ages. However, environmental stimulation reduced these latencies, reversing some damage caused by malnutrition. These data suggest that the auditory brainstem pathway is vulnerable to nutritional insults, and its structures show plasticity with environmental stimulation.

Assuntos

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Mother-pup interaction, as well as other behavioral reactions were studied during the lactation period in 24 litters of Wistar rats and their dams fed either a 16% (control - C; 12 litters) or a 6% (malnourished - M; 12 litters) protein diet. The diets were isocaloric. Throughout lactation there was a 36.4% weight loss of M dams and a 63% body weight deficit in the M pups when compared to control pups. During this period, half of the litters were exposed daily to additional tactile stimulation (CS or MS), while the other half were submitted to normal rearing conditions (CN or MN). The tactile stimulation of pups (handling) consisted of holding the animal in one hand and gently touching the dorsal part of the animal's body with the fingers for 3 min. A special camera and a time-lapse video were used to record litter behavior in their home cages. Starting at 6 p.m. and ending at 6 a.m., on days 3, 6, 12, 15, 18 and 21 of lactation, photos were taken at 4-s intervals. An increase in the frequency (154.88 +/- 16.19) and duration (455.86 +/- 18.05 min) of suckling was observed throughout the lactation period in all groups compared to birth day (frequency 24.88 +/- 2.37 and duration 376.76 +/- 21.01 min), but the frequency was higher in the C (84.96 +/- 8.52) than in the M group (43.13 +/- 4.37); however, the M group (470.2 +/- 11.87 min) spent more time suckling as compared with the C group (393.67 +/- 13.09 min). The M dams showed a decreased frequency of resting position throughout the lactation period (6.5 +/- 2.48) compared to birth day (25.42 +/- 7.74). Pups from the C group were more frequently observed separated (73.02 +/- 4.38) and interacting (258.99 +/- 20.61) more with their mothers than the M pups (separated 66.94 +/- 5.5 and interacting 165.72 +/- 12.05). Tactile stimulation did not interact with diet condition, showing that the kind of stimulation used in the present study did not lead to recovery from the changes induced by protein malnutrition. The changes in mother-pup interaction produced by protein malnutrition of both may represent retardation in neuromotor development and a higher dependence of the pups on their mothers. These changes may represent an important means of energy saving and heat maintenance in malnourished pups.

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The feeding preference of normal rats (n = 14), malnourished rats (n = 14), and enterectomized rats (n = 16) was determined in a situation of free choice of three complete solid diets which only differed in extent of protein polymerization: intact casein, casein hydrolysate, and an amino acid mixture with a composition similar to that of casein. The animals were housed in metabolic cages for 30 days and allowed to freely choose among the three diets presented simultaneously. All three groups showed an initial preference for the intact casein diet. The control group maintained this preference, whereas the malnourished and enterectomized groups reduced the ingestion of the intact casein diet and increased the ingestion of the amino acid diet. The nitrogen balance, which was always positive in all three groups, was constant in the control group (1.51 +/- 0.26 g) initially higher (1.77 +/- 0.19 g) in the malnourished group, with a subsequent fall (1.13 +/- 0.24 g), and lower in the enterectomized group (0.83 +/- 0.32 g). Although total intake was similar for the control and malnourished groups, the malnourished group presented a higher weight recovery (130.2%). In contrast, the food intake of the enterectomized group was much lower, with a small weight gain. After treatment that impairs the digestive tract, intact casein was the initially preferred nitrogen source, which later tended to be replaced with free amino acids. This change was accompanied by an improvement in nitrogen balance and body weight, especially after protein malnutrition. These data may suggest that, in clinical practice, the use of enteral diets containing fully hydrolyzed protein may be of benefit in terms of the recovery of malnourished patients and of patients with short bowel syndrome.

Assuntos

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An increased number of visits and time spent in the open arms of the elevated plus-maze by malnourished rats has been used as indicative of lower anxiety or higher impulsiveness. In order to study how this behavior profile responds to an anxiogenic procedure (short-term social isolation), control (16% protein) and malnourished (6% protein) rats were socially isolated prior to the test in the maze. Litters (dam plus 6 male and 2 female pups) were fed the diets from birth to 49 days of age. From 50 days on, all rats were fed a lab chow diet. Social isolation consists in removing the rats from the group and placing them in individual cages for 2 h before the test. During the test each rat was individually placed on the center of the maze and allowed to explore for 5 min. The results showed higher open arms exploration and lower attempts to enter open arms by the malnourished rats than by the controls. Social isolation decreased open arm exploration and increased time spent on the central platform in control animals, but had no effect on the malnourished rats. The results reinforce the lower anxiety or higher impulsiveness of malnourished rats, as well as the anxiogenic effect of social isolation in control rats. However, the malnourished rats were unresponsive to the anxiogenic effects of social isolation, indicating that protein deficiency early in life not only induces lower anxiety or higher impulsiveness in the maze, but also changes the behavior of these animals in response to another environmentally-induced procedure of anxiety (social isolation).

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A complex program of environmental and sensory stimulation was developed to study its potential effects in reversing some of the alterations produced by early protein malnutrition in the brain and behavior of rats. Litters (dam plus 6 male pups) were fed diets containing 8% (malnourished) or 25% (well-nourished) casein. After weaning, the animals were maintained on the same diets as their respective dams until 50 days of age. Environmental stimulation consisted of 3-min daily handling from birth to 50 days of age. Additional stimulation was provided from birth to 50 days of age by rearing the rats in an enriched living cage and exposing the animals to visual, auditory and olfactory stimuli. At 50 days of age the animals were submitted to locomotor and inhibitory avoidance tests. Animals of the same age were sacrificed, the brain removed and divided in telencephalon, brain steam and cerebellum. DNA and RNA were assessed in telencephalon and cerebellum. Protein malnutrition produced brain weight deficits that were partially reversed by environmental stimulation. DNA and RNA levels were reduced by protein malnutrition and increased by environmental stimulation. The behavioral measures showed lower locomotor activity and higher latencies in inhibitory avoidance for malnourished animals as compared to well-nourished animals. Environmental stimulation reduced the aversiveness in the inhibitory avoidance test as showed by lower latencies in the stimulated group of animals. These results suggest that early protein malnutrition impairs brain and behavior of rats and that a complex program of environmental stimulation is beneficial to reverse some of those impairments.

RESUMO

UNLABELLED: The interaction between the effects of different levels of protein malnutrition and environmental stimulation was investigated in young male rats in the elevated plus-maze (EPM). Litters (dam plus 6 male and 2 female pups) were fed a 16% ( CONTROL: C), 10% (Malnourished: M10) or 6% (Malnourished: M6) protein diet. Half of the litters were daily exposed to additional stimulation (CS, MS10 or MS6), while the other half was maintained in normal rearing conditions (CN, MN10 or MN6). The stimulation (handling) consisted of holding the rat in one hand and gently touching the dorsal part of the body with the fingers for 3 min. On the 22nd day of life (weaning), two male pups from each group were tested in the plus-maze. Two male pups continued to receive the same diet as their mothers, and the other two were fed a non-purified lab chow diet until 35 days of age when they were tested in the plus-maze (LN, LS, LN10, LS10, LN6 and LS6 groups). Results showed that environmental stimulation increased open arms exploration both at 22 and 35 days of age, indicating an anxiolytic effect of this procedure. Younger rats (22 days of age) explored significantly more the open arms of the maze as compared with older rats (35 days of age), indicating an increase in anxiety with age. M6 animals showed significantly higher percentages of open arm entries and less frequent attempts to enter open arms in the maze as compared with C and M10 animals. These results suggest that even a short period of protein deficiency can produce alterations in the emotional response of rats in the elevated plus-maze. In addition, the data demonstrated that protein deficiency more severe than 10% is necessary to produce behavior alterations in the EPM test.

RESUMO

Studies on rats maintained on low-protein-calorie diets during the lactation period show that food intake decreases. This process results in weight loss and a delay in litter development. The purpose of the present study was to determine the alterations in food intake, maternal weight and litter growth during lactation when dams were exposed to diets with different levels of protein and carbohydrate. Female Wistar rats receiving one of 4 different diets, A (N = 14), B (N = 14), C (N = 9) and D (N = 9), were used. Diet A contained 16% protein and 66% carbohydrate; diet B, 6% protein and 77% carbohydrate; diet C, 6% protein and 66% carbohydrate; diet D, 16% protein and 56% carbohydrate. Thus, C and D diets were hypocaloric, while A and B were isocaloric. The intake of a low-protein diet in groups B and C affected the weight of dams and litters during the last two weeks of lactation, while the low-calorie diets limited the growth of D litters at 21 days compared with A litters, but had no effect on the weight of D dams. Group B showed an increase in intake during the first five days of lactation, resulting in a behavioral calorie compensation due to the increase in carbohydrate content, but the intake decreased during the last part of lactation. Food intake regulation predominantly involves the recruitment of a variety of peripheral satiety systems that attempt to decrease the central feeding command system.

Assuntos