Abnormal nocturnal blood pressure fall in normotensive adolescents with insulin-dependent diabetes is ameliorated following glycemic improvement

Lack of the physiological nocturnal fall in blood pressure (BP) has been found in diabetics and it seems to be related to the presence of diabetic complications. The present study examined the changes in the nocturnal BP pattern of 8 normotensive insulin-dependent diabetic adolescents without nephropathy following improvement in glycemic control induced by an 8-day program of adequate diet and exercise. The same number of age- and sex-matched control subjects were studied. During the first and eighth nights of the program, BP was obtained by ambulatory BP monitoring. After a 10-min rest, 3 BP and heart rate (HR) recordings were taken and the mean values were considered to represent their awake values. The monitor was programmed to cuff insufflation every 20 min from 10:00 p.m. to 7:00 a.m. The glycemic control of diabetics improved since glycemia (212.0 ± 91.5 to 140.2 ± 69.1 mg/dl, P<0.03), urine glucose (12.7 ± 11.8 to 8.6 ± 6.4 g/24 h, P = 0.08) and insulin dose (31.1 ± 7.7 to 16.1 ± 9.7 U/day, P<0.01) were reduced on the last day. The mean BP of control subjects markedly decreased during the sleeping hours of night 1 (92.3 ± 6.4 to 78.1 ± 5.0 mmHg, P<0.001) and night 8 (87.3 ± 6.7 to 76.9 ± 3.6 mmHg, P<0.001). Diabetic patients showed a slight decrease in mean BP during the first night. However, the fall in BP during the nocturnal period increased significantly on the eighth night. The average awake-sleep BP variation was significantly higher at the end of the study (4.2 vs 10.3%, P<0.05) and this ratio turned out to be similar to that found in the control group (10.3 vs 16.3%). HR variation also increased on the eighth night in the diabetics. Following the metabolic improvement obtained at the end of the period, the nocturnal BP variation of diabetics was close to the normal pattern. We suggest that amelioration of glycemic control may influence the awake-sleep BP and HR differences. This effect may be due at least in part to an attenuated insulin stimulation of sympathetic activity

A high-fructose diet induces changes in pp185 phosphorylation in muscle and liver of rats

Insulin stimulates the tyrosine kinase activity of its receptor resulting in the tyrosine phosphorylation of pp185, which contains insulin receptor substrates IRS-1 and IRS-2. These early steps in insulin action are essential for the metabolic effects of insulin. Feeding animals a high-fructose diet results in insulin resistance. However, the exact molecular mechanism underlying this effect is unknown. In the present study, we determined the levels and phosphorylation status of the insulin receptor and pp185 (IRS-1/2) in liver and muscle of rats submitted to a high-fructose diet evaluated by immunoblotting with specific antibodies. Feeding fructose (28 days) induced a discrete insulin resistance, as demonstrated by the insulin tolerance test. Plasma glucose and serum insulin and cholesterol levels of the two groups of rats, fructose-fed and control, were similar, whereas plasma triacylglycerol concentration was significantly increased in the rats submitted to the fructose diet (P<0.05). There were no changes in insulin receptor concentration in the liver or muscle of either group. However, insulin-stimulated receptor autophosphorylation was reduced to 72 ± 4% (P<0.05) in the liver of high-fructose rats. The IRS-1 protein levels were similar in both liver and muscle of the two groups of rats. In contrast, there was a significant decrease in insulin-induced pp185 (IRS-1/2) phosphorylation, to 83 ± 5% (P<0.05) in liver and to 77 ± 4% (P<0.05) in muscle of the high-fructose rats. These data suggest that changes in the early steps of insulin signal transduction may have an important role in the insulin resistance induced by high-fructose feeding.

Activation of neural cholecystokinin-1 receptors induces relaxation of the isolated rat duodenum which is reduced by nitric oxide synthase inhibitors

Cholecystokinin (CCK) influences gastrointestinal motility, by acting on central and peripheral receptors. The aim of the present study was to determine whether CCK has any effect on isolated duodenum longitudinal muscle activity and to characterize the mechanisms involved. Isolated segments of the rat proximal duodenum were mounted for the recording of isometric contractions of longitudinal muscle in the presence of atropine and guanethidine. CCK-8S (EC50: 39; 95% CI: 4.1-152 nM) and cerulein (EC50: 58; 95% CI: 18-281 nM) induced a concentration-dependent and tetrodotoxin-sensitive relaxation. Nomeganitro-L-arginine (L-NOARG) reduced CCK-8S- and cerulein-induced relaxation (IC50: 5.2; 95% CI: 2.5-18 µM) in a concentration-dependent manner. The magnitude of 300 nM CCK-8S-induced relaxation was reduced by 100 µM L-NOARG from 73 ± 5.1 to 19 ± 3.5% in an L-arginine but not D-arginine preventable manner. The CCK-1 receptor antagonists proglumide, lorglumide and devazepide, but not the CCK-2 receptor antagonist L-365,260, antagonized CCK-8S-induced relaxation in a concentration-dependent manner. These findings suggest that CCK-8S and cerulein activate intrinsic nitrergic nerves acting on CCK-1 receptors in order to cause relaxation of the rat duodenum longitudinal muscle.

Adenosine A1 receptor-mediated inhibition of in vitro prolactin secretion from the rat anterior pituitary

In previous studies, we demonstrated biphasic purinergic effects on prolactin (PRL) secretion stimulated by an adenosine A2 agonist. In the present study, we investigated the role of the activation of adenosine A1 receptors by (R)-N6-(2-phenylisopropyl)adenosine (R-PIA) at the pituitary level in in vitro PRL secretion. Hemipituitaries (one per cuvette in five replicates) from adult male rats were incubated. Administration of R-PIA (0.001, 0.01, 0.1, 1, and 10 µM) induced a reduction of PRL secretion into the medium in a U-shaped dose-response curve. The maximal reduction was obtained with 0.1 µM R-PIA (mean ± SEM, 36.01 ± 5.53 ng/mg tissue weight (t.w.)) treatment compared to control (264.56 ± 15.46 ng/mg t.w.). R-PIA inhibition (0.01 µM = 141.97 ± 15.79 vs control = 244.77 ± 13.79 ng/mg t.w.) of PRL release was blocked by 1 µM cyclopentyltheophylline, a specific A1 receptor antagonist (1 µM = 212.360 ± 26.560 ng/mg t.w.), whereas cyclopentyltheophylline alone (0.01, 0.1, 1 µM) had no effect. R-PIA (0.001, 0.01, 0.1, 1 µM) produced inhibition of PRL secretion stimulated by both phospholipase C (0.5 IU/mL; 977.44 ± 76.17 ng/mg t.w.) and dibutyryl cAMP (1 mM; 415.93 ± 37.66 ng/mg t.w.) with nadir established at the dose of 0.1 µM (225.55 ± 71.42 and 201.9 ± 19.08 ng/mg t.w., respectively). Similarly, R-PIA (0.01 µM) decreased (242.00 ± 24.00 ng/mg t.w.) the PRL secretion stimulated by cholera toxin (0.5 mg/mL; 1050.00 ± 70.00 ng/mg t.w.). In contrast, R-PIA had no effect (468.00 ± 34.00 ng/mg t.w.) on PRL secretion stimulation by pertussis toxin (0.5 mg/mL; 430.00 ± 26.00 ng/mg t.w.). These results suggest that inhibition of PRL secretion after A1 receptor activation by R-PIA is mediated by a Gi protein-dependent mechanism.

Resistance exercise improves hippocampus-dependent memory

It has been demonstrated that resistance exercise improves cognitive functions in humans. Thus, an animal model that mimics this phenomenon can be an important tool for studying the underlying neurophysiological mechanisms. Here, we tested if an animal model for resistance exercise was able to improve the performance in a hippocampus-dependent memory task. In addition, we also evaluated the level of insulin-like growth factor 1/insulin growth factor receptor (IGF-1/IGF-1R), which plays pleiotropic roles in the nervous system. Adult male Wistar rats were divided into three groups (N = 10 for each group): control, SHAM, and resistance exercise (RES). The RES group was submitted to 8 weeks of progressive resistance exercise in a vertical ladder apparatus, while the SHAM group was left in the same apparatus without exercising. Analysis of a cross-sectional area of the flexor digitorum longus muscle indicated that this training period was sufficient to cause muscle fiber hypertrophy. In a step-through passive avoidance task (PA), the RES group presented a longer latency than the other groups on the test day. We also observed an increase of 43 and 94% for systemic and hippocampal IGF-1 concentration, respectively, in the RES group compared to the others. A positive correlation was established between PA performance and systemic IGF-1 (r = 0.46, P < 0.05). Taken together, our data indicate that resistance exercise improves the hippocampus-dependent memory task with a concomitant increase of IGF-1 level in the rat model. This model can be further explored to better understand the effects of resistance exercise on brain functions.

Ox-LDL increases OX40L in endothelial cells through a LOX-1-dependent mechanism

Oxidative low-density lipoprotein (Ox-LDL) is a key risk factor for the development of atherosclerosis, and it can stimulate the expression of a variety of inflammatory signals. As a new and highly sensitive inflammation index, OX40L may be a key to understanding the mechanisms that regulate interactions between cells within the vessel wall and inflammatory mediators during the development of atherosclerosis. To investigate whether Ox-LDL regulates OX40L expression through an oxidized LDL-1 receptor (LOX-1)-mediated mechanism, we investigated the effect of different concentrations of Ox-LDL (50, 100, 150 µg/mL) on endothelial cell proliferation and apoptosis. Stimulation with Ox-LDL increased OX40L protein 1.44-fold and mRNA 4.0-fold in endothelial cells, and these effects were inhibited by blocking LOX-1. These results indicate that LOX-1 plays an important role in the chronic inflammatory process in blood vessel walls. Inhibiting LOX-1 may reduce blood vessel inflammation and provide a therapeutic option to limit atherosclerosis progression.

Expression of NR1I3 in mouse lung tumors induced by the tobacco-specific nitrosamine 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanone

Nuclear receptor subfamily 1, group I, member 3 (NR1I3) is reported to be a possible novel therapeutic target for some cancers, including lung, brain and hematopoietic tumors. Here, we characterized expression of NR1I3 in a mouse model of lung carcinogenesis induced by 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanone (NNK), the most potent tobacco carcinogen. Lung tumors were collected from mice treated with NNK (400 mg/kg) and euthanized after 52 weeks. Benign and malignant lesions were formalin-fixed and paraffin-embedded for histology and immunohistochemistry, with samples snap-frozen for mRNA analysis. Immunohistochemically, we found that most macrophages and type I and II pneumocytes expressed NR1I3, whereas fibroblasts and endothelial cells were NR1I3−. Compared with benign lesions, malignant lesions had less NR1I3+ tumor cells. Gene expression analysis also showed an inverse correlation between NR1I3 mRNA expression and tumor size (P=0.0061), suggesting that bigger tumors expressed less NR1I3 transcripts, in accordance with our immunohistochemical NR1I3 tests. Our results indicate that NR1I3 expression decreased during progression of malignant lung tumors induced by NNK in mice.

Diagnosis of iron deficiency anemia in children of Northeast Brazil

OBJECTIVE: To diagnose iron deficiency anemia in children. METHODS: The study was conducted with a sample of 301 children aged six to 30 months attending public daycare centers in the city of Recife, Northeast Brazil, in 2004. The diagnoses of anemia were based on a combination of different hematological and biochemical parameters: hemoglobin, mean corpuscular volume, ferritin, C-reactive protein, transferrin saturation and transferrin receptor. The chi-square test and ANOVA were used in the statistical analysis. RESULTS: Of all children studied, 92.4% had anemia (Hb <110 g/L) and 28.9% had moderate/severe anemia (Hb <90 g/L). Lower levels of hemoglobin were found in children aged 6-17 months. Iron deficiency was found in 51.5% of children using ferritin (<12 μg/L) as parameter. Taking into consideration the combination of hemoglobin level, ferritin and transferrin receptor, 58.1% had anemia with iron deficiency, 34.2% had anemia without iron deficiency and 2.3% had iron deficiency without anemia. Mean ferritin concentration was significantly higher in children with high C-reactive protein when compared with those with normal levels (22.1 vs. 14.8 µg/L). CONCLUSIONS: The use of several biochemical and hematological parameters allowed to diagnosing iron deficiency anemia in two thirds of children, suggesting a need to identify other determinants of anemia without iron deficiency.

Clinical and laboratory characteristics associated with dyslipidemia and liver steatosis in chronic HBV carriers

Introduction Chronic hepatitis B virus (HBV) infection and liver steatosis (LS) are the most common causes of chronic liver disease, and their coexistence is frequently observed in clinical practice. Although metabolic syndrome is the main cause of LS, it has not been associated with HBV infection. The aims of this study were to describe the lipid profile and prevalence of LS among HBV carriers and to identify the characteristics associated with LS in this group. Methods This retrospective cross-sectional study included hepatitis B surface antigen (HBsAg)-positive patients evaluated during 2011 and 2012. Results Of the 83 patients included, the mean age was 46.4&#177;12.5 years, 53% were men, and 9.1% were hepatitis B e antigen (HBeAg) -positive. These patients exhibited the following lipid profile: total cholesterol = 175.4&#177;38.8mg/dL, low-density lipoprotein (LDL) = 113.0&#177;32.7mg/dL, and triglycerides = 91.1&#177;45.2mg/dL. Their fasting glucose was 95.3&#177;14.5g/dL, and fasting insulin was 6.1&#177;5.9&#181;IU/mL. Liver steatosis was observed on abdominal ultrasound in 11.3% of individuals. Factors associated with the presence of LS included higher levels of total cholesterol, prothrombin activity, fasting insulin, and body mass index (BMI) as well as lower levels of aspartate aminotransferase (AST). Conclusions These findings suggest that LS in patients with chronic HBV appears to be a consequence of metabolic alterations and insulin action rather than of viral factors.

Análise combinada de fatores genéticos e ambientais na hipertensão essencial em um município da região Amazônica

OBJETIVO: Este estudo avaliou a contribuição de seis polimorfismos genéticos presentes em genes do sistema renina-angiotensina-aldosterona (SRAA) e fatores de risco clínicos para o desenvolvimento da hipertensão arterial essencial em um município da região Amazônica. MÉTODOS: Oitenta e dois indivíduos hipertensos e setenta e oito indivíduos normotensos foram genotipados quanto à presença de polimorfismos REN-G1051A (renina), AGT-M235T (angiotensinogênio), ECA-Alu I/D (enzima conversora de angiotensina I), AGTR1-A1166C (receptor tipo 1 da angiotensina II) e CYP11B2-C344T (aldosterona sintetase) pela técnica de reação em cadeia da polimerase (PCR), com análise de restrição quando necessário. A influência de polimorfismos genéticos e fatores de risco clínicos na variação da pressão arterial foi avaliada por meio de regressão linear stepwise. RESULTADOS: Relatamos a co-ocorrência de fatores de risco clínicos e polimorfismo do gene da enzima conversora de angiotensina (ECA) na população de um município da região amazônica. Nossos resultados mostram que a elevação da pressão arterial sistólica é favorecida pelo alelo D do polimorfismo de inserção/deleção do gene da ECA e pelo aumento da idade, enquanto consumo de bebida alcoólica e envelhecimento estão associados ao aumento da pressão arterial diastólica (PAD). CONCLUSÃO: Esses achados indicam que os moradores de Santa Isabel do Rio Negro que possuem o alelo D da ECA ou têm o hábito de beber apresentam valores mais elevados de PAS e PAD, respectivamente, com o passar dos anos.

Coffee seedlings in different substrates and protected environments

The production of high-quality seedlings is a critical factor for successful implementation of a determined crop in the field. In order to evaluate the production of coffee seedlings, experiments were conducted with different substrates and in different protected environments. Treatments consisted of evaluation of the following substrates: 50% cattle manure + 50% commercial substrate, 50% cattle manure + 50% vermiculite, 50% commercial substrate + 50% vermiculite, 1/3 cattle manure + 1/3 commercial substrate + 1/3 vermiculite, 50% cattle manure + 50% sand, 1/3 sand + 1/3 cattle manure + 1/3 commercial substrate and 50% commercial substrate + 50% sand. These substrates were tested in different protected environments: agricultural greenhouse, mesh screen with 50% shading, aluminized screen with 50% shading, black screen with 30% shading, black screen with 70% shading, nursery with a buriti straw roof and full sunlight. In each environment, the experiments were conducted in a completely randomized design with five replicates of four plants each followed by joint analysis. The substrates containing 50% cattle manure associated with vermiculite or the commercial substrate may be indicated for production of coffee seedlings. Screened environments with 30, 50 and 70% shading resulted in the highest quality seedlings.

Morphological and immunohistochemical characterization of angiogenic and apoptotic factors and the expression of thyroid receptors in the ovary of tilapia Oreochromis niloticus in captivity

Morphological and immunohistochemical characterization of angiogenic and apoptotic factors and the expression of thyroid receptors in the ovary of tilapia Oreochromis niloticus in captivity were studied. The morphological evaluation of the ovaries was performed by histological paraffin embedded and stained with HE. The immunohistochemical expressions of CDC47, VEGF, Flk-1, angiopoietin, Tie-2 and thyroid receptor (TRα) were performed by the technique of streptavidein-biotin-peroxidase. Apoptosis was assessed using the TUNEL kit. The relative expression of thyroid hormone receptors (TRα and TRβ) was assessed by RT-PCR real time. The nuclear expression of CDC47 increased with the stage of maturation of the oocyte and was observed in the follicle cells. Apoptotic bodies were observed in the follicular cells of atretic follicles and postovulatory follicles from the ovaries of 150g and 350g fish. Expression of VEGF and its receptor Flk-1 was also observed in the follicular cells, and the expression of both increased with the maturity of the oocyte, with a higher intensity observed in the full-grown follicle. The expression of angiopoietin and of its receptor (Tie 2) was discrete and moderate respectively. TRα expression was independent of follicular development. However, the 350 g tilapia exhibited higher expression of TRβ compared with the 50 g tilapia. We conclude that the proliferative activity and the expression of VEGF and its receptor increase with follicular maturation and that the TRs expression increases with ovarian maturity in tilapia (Oreochromis niloticus).

Baroreflex and chemoreflex dysfunction in streptozotocin-diabetic rats

Several investigators have demonstrated that streptozotocin (STZ) diabetes induces changes in the autonomic control of the cardiovascular system. Changes in cardiovascular function may be related to peripheral neuropathy. The aim of the present study was to analyze changes in heart rate (HR) and arterial pressure (AP) as well as baroreflex and chemoreflex sensitivity in STZ-induced diabetic male Wistar rats (STZ, 50 mg/kg, iv, 15 days). Intra-arterial blood pressure signals were obtained for control and diabetic rats (N = 9, each group). Data were processed in a data acquisition system (CODAS, 1 kHz). Baroreflex sensitivity was evaluated by measuring heart rate changes induced by arterial pressure variation produced by phenylephrine and sodium nitroprusside injection. Increasing doses of potassium cyanide (KCN) were used to evaluate bradycardic and pressor responses evoked by chemoreflex activation. STZ induced hyperglycemia (447 ± 49 vs 126 ± 3 mg/dl), and a reduction in AP (99 ± 3 vs 118 ± 2 mmHg), resting HR (296 ± 11 vs 355 ± 16 bpm) and plasma insulin levels (16 ± 1 vs 57 ± 11 µU/ml). We also observed that the reflex bradycardia (-1.68 ± 0.1 vs -1.25 ± 0.1 bpm/mmHg, in the diabetic group) and tachycardia (-3.68 ± 0.5 vs -1.75 ± 0.3 bpm/mmHg, in the diabetic group) produced by vasopressor and depressor agents were impaired in the diabetic group. Bradycardia evoked by chemoreflex activation was attenuated in diabetic rats (control: -17 ± 1, -86 ± 19, -185 ± 18, -208 ± 17 vs diabetic: -7 ± 1, -23 ± 5, -95 ± 13, -140 ± 13 bpm), as also was the pressor response (control: 6 ± 1, 30 ± 7, 54 ± 4, 59 ± 5 vs diabetic: 6 ± 1, 8 ± 2, 33 ± 4, 42 ± 5 mmHg). In conclusion, the cardiovascular responses evoked by baroreflex and chemoreflex activation are impaired in diabetic rats. The alterations of cardiovascular responses may be secondary to the autonomic dysfunction of cardiovascular control

Biosynthesis and metabolism of steroid hormones by human adrenal carcinomas

Over a 15-year period, our university-based laboratory obtained 125 adrenal tumors, of which 15 (12%) were adrenal cortical carcinomas. Of these, 6 (40% of the carcinomas) occurred in patients with clear clinical manifestations of steroid hormone excess. Adrenal cortical carcinoma cells derived from the surgically resected tumors in 4 of these patients were isolated and established in primary culture. Radiotracer steroid interconversion studies were carried out with these cultures and also on mitochondria isolated from homogenized tissues. Large tumors had the lowest steroidogenic activities per weight, whereas small tumors had more moderately depressed enzyme activities relative to cells from normal glands. In incubations with pregnenolone as substrate, 1 mM metyrapone blocked the synthesis of corticosterone and cortisol and also the formation of aldosterone. Metyrapone inhibition was associated with a concomitant increase in the formation of androgens (androstenedione and testosterone) from pregnenolone. Administration of metyrapone in vivo before surgery in one patient resulted in a similar increase in plasma androstenedione, though plasma testosterone levels were not significantly affected. In cultures of two of four tumors examined, dibutyryl cAMP stimulated 11ß-hydroxylase activity modestly; ACTH also had a significant stimulatory effect in one of these tumors. Unlike results obtained with normal or adenomatous adrenal cortical tissues, mitochondria from carcinomatous cells showed a lack of support of either cholesterol side-chain cleavage enzyme complex or steroid 11ß-hydroxylase activity by Krebs cycle intermediates (10 mM isocitrate, succinate or malate). This finding is consistent with the concept that these carcinomas may tend to function predominantly in an anaerobic manner, rather than through the oxidation of Krebs cycle intermediates.

Normal expression of IFN-gammaR in four patients with uncommon mycobacterial infection phenotypes

Several primary immunodeficiency diseases affecting the interleukin 12/interferon gamma (IFN-gamma) pathway have been identified, most of them characterized by recurrent and protracted infections produced by intracellular microorganisms, particularly by several species of mycobacteria. In the present study we analyzed the expression of IFN-gamma receptor (IFN-gammaR) and signal transducer and activator of transcription 1 (STAT-1) in 4 children with Mycobacterium tuberculosis infection of uncommon clinical presentation. These molecules were evaluated by flow cytometry and Western blotting in B cells transformed with Epstein-Barr virus and mutations were scanned by single-strand conformational polymorphisms and DNA sequencing. The expression of IFN-gammaR1 was normal in all 4 patients. The genetic analysis of IFN-gammaR1 and IFN-gammaR2 coding sequences did not reveal any mutation. The expression of the STAT-1 molecule was similar in patients and healthy controls; however, when the phosphorylation of this transcription factor in response to IFN-gamma activation was evaluated by Western blot, a significant lower signal was evident in one patient. These data indicate that there are no alterations in the expression or function of the IFN-gammaR chains in these patients. However, the low level of STAT-1 phosphorylation found in one of these patients might be explained by a defect in one of the molecules involved in the signal transduction pathway after IFN-gamma interacts with its receptor. In the other three patients the inability to eliminate the mycobacteria may be due to a defect in another effector mechanism of the mononuclear phagocytes.