Effects of fumonisin B1 on selected biological responses and performance of broiler chickens

The objective of this study was to determine the effects of three doses of fumonisin B1 (0, 100, and 200mg/kg of feed) on biological variables (relative weight of liver [RWL], total plasma protein [TPP], albumin [Alb], calcium [Ca], phosphorus [P], uric acid [UA], alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma glutamyltransferase [GGT], alkaline phosphatase [AP], total cholesterol [Chol], triglycerides [Tri], sphinganine-to-sphingosine ratio [SA:SO], and C-reactive protein [CRP]), morphological evaluation of the small intestine (villus height [VH], crypt depth [CD], and villus-to-crypt ratio [V:C]), histological evaluation, and on performance (body weight [BW], feed intake [FI], and feed conversion rate [FCR]) of broiler chickens. Significant effects of FB were observed on BW and FI (reduced), on RWL, TPP, Ca, ALT, AST, GGT, Chol, and Tri (increased) at both 14 and 28 days evaluations. In addition, significant increase was observed on FCR, Alb, P, SA:SO, and CRP and significant reduction in UA, VH, and V:C only at the 28 days evaluation. Significant histological lesions were observed on liver and kidney of FB inoculated broilers at 14 and 28 days. Those results show that FB has a significant effect on biological and histological variables and on performance of broiler chickens.

Growth, biomass allocation and photosynthesis of Rolandra fruticosa (asteraceae) in response to shade

The effects of shade on growth, biomass allocation patterns and photosynthetic response was examined for Rolandra fruticosa (L.) Kuntze, a common perennial weed shrub in cultivated pastures and agricultural areas of Brazilian Amazonia, for plants grown in full sunlight and those shaded to 30 % of full sunlight over a 34-d period. Specific leaf area and leaf area ratio were higher for shade plants during all the experimental period. Shade plants allocated significantly less biomass to root tissue than sun plants and relative growth rate was higher in sun plants. Sun leaves had significantly higher dark respiration and light saturated rates of photosynthesis than shade leaves. The apparent quantum efficiency was higher for shade leaves, while light compensation point was higher for sun leaves. These results are discussed in relation to their ecological and weed management implications.

Growth of the crabgrass species Digitaria ciliaris and Digitaria nuda

The aim of this research paper was to compare the growth of D. ciliaris and D. nuda crabgrass species under non-competitive conditions. To this end, two experiments were conducted, one from March - July 2010 and the other from February - June 2011. The experimental design of both trials was completely randomized making a factorial (2 seasons x 2 species crabgrass x 12 evaluation periods) with four replications. Assessments began at 15 days after sowing (DAS), and repeated weekly until 92 DAS. The variables evaluated were total dry matter (roots+leaves+stems), leaf area, leaf number and tiller. The results were submitted to analysis of variance and the absolute growth rate, relative growth rate and leaf area ratio were calculated using the means, which were adjusted regression models. The crabgrass species were significantly different in leaf area, leaf number, tiller number and dry matter per plant. D. ciliaris for all variables was statistically higher than D. nuda. Regarding the speed at which the growth of the species occurred, the absolute growth rate and relative growth rate of D. ciliaris was also greater than D. nuda. In addition, D. ciliaris also had a lower leaf area ratio indicating greater efficiency in converting light energy into carbohydrates. It can be concluded that D. ciliaris has a higher growth rate in conditions where there is no limitation of nutrients and water availability in relation to D. nuda, mainly due to D. ciliaris have greater leaf area, number of leaves and dry matter accumulation per plant.

Germination and growth of Fimbristylis miliacea biotypes resistant and susceptible to acetolactate synthase-inhibiting herbicides

Weed biotypes resistant and susceptible to herbicides may have differences in their adaptive values. The aims of this study were to compare, under controlled and non-competitive condition, the growth analysis, germination features and seed weight of Fimbristylis miliacea (FIMMI) biotypes resistant and susceptible to acetolactate synthase (ALS) inhibiting herbicides. Experiments were conducted in a greenhouse and in a laboratory from October 2008 to February 2010. Two resistant biotypes (FIMMI 10 and FIMMI 12) and one susceptible biotype (FIMMI 13) were used for the studies. For the study on growth analysis, the treatments were arranged in a completely randomized experimental design with four replications and sampled at 21, 28, 35, 42, 49, 56, 69 days after emergence (DAE) and at flowering stage. For the studies on germination speed, germination and seed weight, the indexes for germination speed, percentage of germination at different temperatures and seed weight of the biotypes were determined. The results showed that the resistant biotype FIMMI 12 shows differences in all variables compared to the resistant biotype FIMMI 10 and compared to the susceptible biotype FIMMI 13, only for the evaluation at flowering. The susceptible biotype FIMMI 13 showed a higher germination speed index and higher germination rate when compared with the resistant biotypes. On the other hand, the resistant biotypes FIMMI 10 and FIMMI 12 showed higher seed weight.

Growth and leaf demography of two Cecropia species

Allometry, growth and leaf demography of two Cecropia species, one with ant mutualist (C. glazioui) and another without it (C. hololeuca), were studied in an Atlantic Rain Forest area in the State of Rio de Janeiro, SE Brazil. Stem diameter was allometrically related to height in both species. Cecropia glazioui showed higher annual growth rates and longer internodes than C. hololeuca. Leaf phenology showed a seasonal pattern in both species, but the number of leaves on each plant was more variable along the year in C. hololeuca than in C. glazioui. Survivorship curves for leaves were intermediate between Deevey's Type I and Type II curves, with young leaves of C. glazioui showing a greater survival rate and life expectancy than those of C. hololeuca. Low variability in leaf production throughout the year and high survival rate for young leaves of C. glazioui may be characteristics related to its association with ants.

Assimilate partitioning in leaves of the raffinose-storing herb Lamium album L.: photosynthesis and carbon partitioning throughout the photoperiod

Lamium album accumulates starch, sucrose and raffinose-family oligosaccharides (RFO) as the major products of photosynthesis. These products were measured in leaves throughout a sixteen-hour photoperiod and under various irradiance conditions. There was continuous accumulation of sucrose and starch. The rate of gas exchange was higher at 500 µEm² s-1 and 900 µEm²s-1 than at 300 µEm² s-1. The rate of photosynthesis did not decline over the sixteen-hour photoperiod, which suggested that there was no short-term feed back inhibition due to sucrose accumulation in this plant. When the products of photosynthesis were compared at the end of the photoperiod, only sucrose increased in abundance at high irradiance. The RFO pool in leaves was shown to contain raffinose, stachyose and verbascose; galactinol was also present. 14CO2 feeding demonstrated that roots and flowers were the major sinks. The middle leaves were major source leaves whilst young leaves acted as both sources and sinks.

Genetic variability in salt tolerance during germination of Stylosanthes humilis H.B.K. and association between salt tolerance and isozymes

Variation in salt tolerance of six natural populations of Stylosanthes humilis from three ecogeographic regions, Mata (wet tropical climate), Agreste and Sertão (semi-arid tropical climate) of Pernambuco State, Northeast Brazil, was evaluated on germination in 201 mM NaCl. There were significant differences among families of all populations for germination percentage and of five populations (except Tamandaré, from Mata) for germination rate. Populations from semi-arid regions presented high coefficients of genetic variation, those from Agreste being higher than those from Sertão. Populations from Mata showed low coefficients of genetic variation. The coefficients of genotypic determination were high for five populations, except Tamandaré, both for germination percentage ( > or = 0.89) and for germination rate ( > or = 0.79), indicating the possibility of selection for salt tolerance in these populations. An electrophoretic analysis of esterase and peroxidase isozymes was also performed in the six populations, and correlations were estimated between salt tolerance and allelic frequencies. The analysis of salt tolerant and salt sensitive families of populations from Agreste suggested an association of alleles of a peroxidase locus with salt tolerance during germination in the Caruaru population

MHC-restricted antigen presentation and recognition: constraints on gene, recombinant and peptide vaccines in humans

The target of any immunization is to activate and expand lymphocyte clones with the desired recognition specificity and the necessary effector functions. In gene, recombinant and peptide vaccines, the immunogen is a single protein or a small assembly of epitopes from antigenic proteins. Since most immune responses against protein and peptide antigens are T-cell dependent, the molecular target of such vaccines is to generate at least 50-100 complexes between MHC molecule and the antigenic peptide per antigen-presenting cell, sensitizing a T cell population of appropriate clonal size and effector characteristics. Thus, the immunobiology of antigen recognition by T cells must be taken into account when designing new generation peptide- or gene-based vaccines. Since T cell recognition is MHC-restricted, and given the wide polymorphism of the different MHC molecules, distinct epitopes may be recognized by different individuals in the population. Therefore, the issue of whether immunization will be effective in inducing a protective immune response, covering the entire target population, becomes an important question. Many pathogens have evolved molecular mechanisms to escape recognition by the immune system by variation of antigenic protein sequences. In this short review, we will discuss the several concepts related to selection of amino acid sequences to be included in DNA and peptide vaccines.

Relationship between the actions of atrial natriuretic peptide (ANP), guanylin and uroguanylin on the isolated kidney

Guanylin and uroguanylin are peptides that bind to and activate guanylate cyclase C and control salt and water transport in many epithelia in vertebrates, mimicking the action of several heat-stable bacteria enterotoxins. In the kidney, both of them have well-documented natriuretic and kaliuretic effects. Since atrial natriuretic peptide (ANP) also has a natriuretic effect mediated by cGMP, experiments were designed in the isolated perfused rat kidney to identify possible synergisms between ANP, guanylin and uroguanylin. Inulin was added to the perfusate and glomerular filtration rate (GFR) was determined at 10-min intervals. Sodium was also determined. Electrolyte dynamics were measured by the clearance formula. Guanylin (0.5 µg/ml, N = 12) or uroguanylin (0.5 µg/ml, N = 9) was added to the system after 30 min of perfusion with ANP (0.1 ng/ml). The data were compared at 30-min intervals to a control (N = 12) perfused with modified Krebs-Hanseleit solution and to experiments using guanylin and uroguanylin at the same dose (0.5 µg/ml). After previous introduction of ANP in the system, guanylin promoted a reduction in fractional sodium transport (%TNa+, P<0.05) (from 78.46 ± 0.86 to 64.62 ± 1.92, 120 min). In contrast, ANP blocked uroguanylin-induced increase in urine flow (from 0.21 ± 0.01 to 0.15 ± 0.007 ml g-1 min-1, 120 min, P<0.05) and the reduction in fractional sodium transport (from 72.04 ± 0.86 to 85.19 ± 1.48, %TNa+, at 120 min of perfusion, P<0.05). Thus, the synergism between ANP + guanylin and the antagonism between ANP + uroguanylin indicate the existence of different subtypes of receptors mediating the renal actions of guanylins.

Long-term outcome of 25 children and adolescents with severe aplastic anemia treated with antithymocyte globulin

Severe aplastic anemia (SAA) is probably an immune-mediated disorder, and immunosuppressive therapy is recommended for patients with no available donor for bone marrow transplant. Between October 1984 and November 1987, 25 consecutive children and adolescents with SAA with no HLA-compatible marrow donor received equine antithymocyte globulin (ATG) (15 mg kg-1 day-1) for 10 days. The patients were evaluated 6 weeks, 6 months, and 12 months after starting ATG treatment. Thereafter, patients were evaluated yearly until July 1998. Median age was 10 years (range, 1.5-20 years), granulocyte counts on referral ranged from 0.032 to 1.4 x 10(9)/l (median 0.256 x 10(9)/l), and 12 patients had granulocyte counts <0.2 x 10(9)/l. At a median follow-up of 9.6 years (range, 8.6-11.8 years), 10 patients (40%) remained alive with good marrow function. No morphologic evidence of hematological clonal disorders has been observed, although two patients probably have acquired clonal chromosomal abnormalities (trisomy 8 and del(6)q21, respectively). Responses to ATG were observed between 6 weeks and 6 months from the start of treatment in 60% of evaluable patients. The response rate was not different in patients whose granulocyte count at diagnosis was <0.2 x 10(9)/l, or in those who were <10 years of age. This study supports the view that, when compared with supportive measures, ATG is an effective treatment for children or adolescents with SAA. Although these results are inferior to those reported for marrow transplantation or more intensive immunosuppressive regimens, these patients who responded to ATG are long-term survivors with stable peripheral blood counts and a low rate of relapse.

Effects of exercise training on autonomic and myocardial dysfunction in streptozotocin-diabetic rats

Several investigators have demonstrated that diabetes is associated with autonomic and myocardial dysfunction. Exercise training is an efficient non-pharmacological treatment for cardiac and metabolic diseases. The aim of the present study was to investigate the effects of exercise training on hemodynamic and autonomic diabetic dysfunction. After 1 week of diabetes induction (streptozotocin, 50 mg/kg, iv), male Wistar rats (222 ± 5 g, N = 18) were submitted to exercise training for 10 weeks on a treadmill. Arterial pressure signals were obtained and processed with a data acquisition system. Autonomic function and intrinsic heart rate were studied by injecting methylatropine and propranolol. Left ventricular function was assessed in hearts perfused in vitro by the Langendorff technique. Diabetes (D) bradycardia and hypotension (D: 279 ± 9 bpm and 91 ± 4 mmHg vs 315 ± 11 bpm and 111 ± 4 mmHg in controls, C) were attenuated by training (TD: 305 ± 7 bpm and 100 ± 4 mmHg). Vagal tonus was decreased in the diabetic groups and sympathetic tonus was similar in all animals. Intrinsic heart rate was lower in D (284 ± 11 bpm) compared to C and TD (390 ± 8 and 342 ± 14 bpm, respectively). Peak systolic pressure developed at different pressures was similar for all groups, but +dP/dt max was decreased and -dP/dt max was increased in D. In conclusion, exercise training reversed hypotension and bradycardia and improved myocardial function in diabetic rats. These changes represent an adaptive response to the demands of training, supporting a positive role of physical activity in the management of diabetes.

Somaclonal variation: a morphogenetic and biochemical analysis of Mandevilla velutina cultured cells

Cell cultures of Mandevilla velutina have proved to be an interesting production system for biomass and secondary metabolites able to inhibit the hypotensive activity of bradykinin, a nonapeptide generated in plasma during tissue trauma. The crude ethyl acetate extract of cultured cells contains about 31- to 79-fold more potent anti-bradykinin compounds (e.g., velutinol A) than that obtained with equivalent extracts of tubers. Somaclonal variation may be an explanation for the wide range of inhibitor activity found in the cell cultures. The heterogeneity concerning morphology, differentiation, carbon dissimilation, and velutinol A production in M. velutina cell cultures is reported. Cell cultures showed an asynchronous growth and cells in distinct developmental stages. Meristematic cells were found as the major type, with several morphological variations. Cell aggregates consisting only of meristematic cells, differentiated cells containing specialized cell structures such as functional chloroplasts (cytodifferentiation) and cells with embryogenetic characteristics were observed. The time course for sucrose metabolism indicated cell populations with significant differences in growth and metabolic rates, with the highest biomass-producing cell line showing a cell cycle 60% shorter and a metabolic rate 33.6% higher than the control (F2 cell population). MALDI-TOF mass spectrometric analysis of velutinol A in selected cell lines demonstrated the existence of velutinol A producing and nonproducing somaclones. These results point to a high genetic heterogeneity in general and also in terms of secondary metabolite content.

Vertical growth phase and positive sentinel node in thin melanoma

Sentinel node (SN) status is the most important prognostic factor for localized melanoma. Usually, patients with Breslow thickness of less than 1.0 mm are not included in SN protocols. However, the literature presents a rate ranging from 3 to 7% of nodal recurrence in thin melanoma. Ulceration, regression and high mitotic rate have been considered to be indications for an SN biopsy. The metastatic potential of the vertical growth phase is uncertain. To correlate pathological features in thin melanoma with SN metastasis, we reviewed 358 patients submitted to SN biopsy. Seventy-seven patients with lesions of 1 mm or smaller were included in the study group. Histological evaluation of the primary tumor included thickness, Clark level, mitotic rate, ulceration, regression, and growth phase. Lymphoscintigraphy was performed on all patients. Lymphatic mapping and gamma probe detection were both used for SN biopsy. Histological examination of SN consisted of hematoxylin-eosin and immunohistochemical staining. Median follow-up was 37 months. Six patients had micrometastases. Statistical analysis by the Fisher test showed that ulceration (P = 0.019), high mitotic rate (P = 0.008) and vertical growth phase (P = 0.002) were positively correlated with micrometastases. If other studies confirm these results, more melanoma patients must be submitted to SN biopsy.

Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats

The effect of swimming training (ST) on vagal and sympathetic cardiac effects was investigated in sedentary (S, N = 12) and trained (T, N = 12) male Wistar rats (200-220 g). ST consisted of 60-min swimming sessions 5 days/week for 8 weeks, with a 5% body weight load attached to the tail. The effect of the autonomic nervous system in generating training-induced resting bradycardia (RB) was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. Cardiac hypertrophy was evaluated by cardiac weight and myocyte morphometry. Plasma catecholamine concentrations and citrate synthase activity in soleus muscle were also determined in both groups. Resting heart rate was significantly reduced in T rats (355 ± 16 vs 330 ± 20 bpm). RB was associated with a significantly increased cardiac vagal effect in T rats (103 ± 25 vs 158 ± 40 bpm), since the sympathetic cardiac effect and intrinsic heart rate were similar for the two groups. Likewise, no significant difference was observed for plasma catecholamine concentrations between S and T rats. In T rats, left ventricle weight (13%) and myocyte dimension (21%) were significantly increased, suggesting cardiac hypertrophy. Skeletal muscle citrate synthase activity was significantly increased by 52% in T rats, indicating endurance conditioning. These data suggest that RB induced by ST is mainly mediated parasympathetically and differs from other training modes, like running, that seems to mainly decrease intrinsic heart rate in rats. The increased cardiac vagal activity associated with ST is of clinical relevance, since both are related to increased life expectancy and prevention of cardiac events.

Prevalence of retinopathy in Caucasian type 2 diabetic patients from the South of Brazil and relationship with clinical and metabolic factors

Diabetic retinopathy (DR) is a sight-threatening chronic complication of diabetes mellitus and is the leading cause of acquired blindness in adults. In this cross-sectional study, we investigated the prevalence of and the factors associated with DR in an analysis of 210 consecutive and unrelated Brazilian Caucasians with type 2 diabetes mellitus. Retinopathy was evaluated by ophthalmoscopy and/or biomicroscopy through dilated pupils. The relationship between clinical and metabolic variables and the presence of DR was assessed by logistic regression analysis. DR was detected in 99 of the 210 patients (47%). In the univariate logistic regression analyses, male sex, duration of diabetes, body mass index, glycated hemoglobin, C-peptide, LDL cholesterol, smoking, and albumin excretion rate were found to be associated with the presence of DR. However, the multiple logistic regression analysis showed that only duration of diabetes (odds ratio (OR) = 1.15, 95% CI = 1.09-1.22; P < 0.001), glycated hemoglobin (OR = 1.21, 95% CI = 1.01-1.46; P = 0.047) and albumin excretion rate >100 µg/min (OR = 12.72, 95% CI = 3.89-41.56; P < 0.001) were independently associated with DR. Although DR was found to be frequent among Brazilian type 2 diabetic patients, its prevalence was within the range observed in other Caucasian populations. Our findings emphasize the need for good glycemic control in order to prevent or delay the onset of DR, since the most well-known risk factors for the development of this complication in type 2 diabetes mellitus, such as duration of diabetes, glycated hemoglobin and albumin excretion rate were independently related to DR.