Molecular biology and biochemistry of brain tumours

ßElucidating some molecular mechanisms and biochemistry of brain tumours is an important step towards the development of adjuvant medical therapies. The present study concentrates on cholecystokinin (CCK), a gut-brain peptide that has been described to be able to induce mitosis of rat gliomas as well as hormone secretion by the anterior pituitary, via the CCK-B receptor. The significance of a polymorphism in the growth hormone releasing hormone (GHRH) receptor (GHRH-R) gene was also determined. Finally, defects in the ß-catenin gene, an important component of the developmental pathway, in a sub-set of craniopharyngiomas were investigated. Reverse transcription-polymerase chain reaction (RT-PCR), restriction digestion analysis and direct sequencing demonstrated expression of CCK peptide itself and its A and B receptors by human gliomas, meningiomas and pituitary tumours. CCK peptides stimulated growth of cultured gliomas and meningiomas as well as in vitro hormone secretion [growth hormone (GH), luteinizing hormone (LH) and follicle stimulating hormone (FSH)] by human pituitary tumours. These biological effects were reduced or abolished by CCK antagonists. In addition, an antibody to CCK reduced mitosis by gliomas and meningiomas, and the same antibody inhibited hormone secretion by cultured human pituitary tumours. CCK peptides stimulated phosphatidylinositol (PI) hydrolysis, indicating coupling of the CCK receptors to phopsholipase C. Cyclic AMP was unaffected. In addition, caspase-3 activity was significantly and markedly increased, whilst proteasome activity was decreased. Taken together, these results may indicate an autocrine/paracrine role of CCK in the control of growth and/or functioning of gliomas, meningiomas and pituitary tumours. Primer induced restriction analysis (PIRA) of a rarer and alternative polymorphism in the GHRH-R receptor, in which Thr replaces Ala at codon 57, in human GH-secreting pituitary tumours was investigated. Whilst the rarer form correlated with an increased response of the pituitary cells to GHRH in vitro, allele distribution studies revealed that it is unlikely that the polymorphism contributes to increased risk of developing GH-secreting tumours and therefore acromegaly. Further findings of this study, using PCR and direct sequencing, were the demonstration of an association between b-catenin gene alterations and craniopharyngiomas of the adamantinomatous type. Since this gene product is involved with development, these results suggest that p-catenin mutations may contribute to the initiation and subsequent growth of congenital adamantinomatous craniopharyngiomas.

The primary amine metabolite of sibutramine stimulates lipolysis in adipocytes isolated from lean and obese mice and in isolated human adipocytes

Sibutramine is a satiety-inducing serotonin-noradrenaline reuptake inhibitor that acts predominantly via its primary and secondary metabolites. This study investigates the possibility that sibutramine and/or its metabolites could act directly on white adipose tissue to increase lipolysis. Adipocytes were isolated by a collagenase digestion procedure from homozygous lean (+/+) and obese-diabetic ob/ob mice, and from lean nondiabetic human subjects. The lipolytic activity of adipocyte preparations was measured by the determination of glycerol release over a 2-hour incubation period. The primary amine metabolite of sibutramine M2, caused a concentration-dependent stimulation of glycerol release by murine lean and obese adipocytes (maximum increase by 157 ± 22 and 245 ± 1696, respectively, p < 0.05). Neither sibutramine nor its secondary amine metabolite M1 had any effect on lipolytic activity. Preliminary studies indicated that M2-induced lipolysis was mediated via a beta-adrenergic action. The non-selective beta-adrenoceptor antagonist propranolol (10-6M) strongly inhibited M2-stimulated lipolysis in lean and obese murine adipocytes. M2 similarly increased lipolysis by isolated human omental and subcutaneous adipocytes (maximum increase by 194 ± 33 and 136 ± 4%, respectively, p < 0.05) with EC50 values of 12 nM and 3 nM, respectively. These results indicate that the sibutramine metabolite M2 can act directly on murine and human adipose tissue to increase lipolysis via a pathway involving beta-adrenoceptors. © Georg Thieme Verlag KG Stuttgart.

Insulin-like growth factor-I gene expression as a growth indicator in Nile tilapia Oreochromis niloticus L.

Somatic growth in fishes is regulated by a variety of hormones. A central step in this hormonal network is the growth hormone-insulin-like growth factor-I (IGF-I) axis. Studies conducted evaluated the relationship of hepatic IGF-I (hIGF-1) mRNA with growth as affected by feeding regimes (satiation or restricted level; daily or alternate-day feeding), temperatures (high, ambient, low) and by social stress. To develop a cellular means for the quantification of hIGF-I mRNA levels in O. niloticus, hIGF-I cDNA was isolated and cloned. The partial sequence of IGF-I cDNA encodes for signal peptide, mature protein and a portion of the E-domain. A sensitive TaqMan quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed based on the mature IGF-I. Using the developed qRT-PCR assay a significant positive correlation was observed between hIGF-I mRNA levels and growth rate of fish reared under different feeding regimes (r = 0.64) and temperature conditions (r = 0.64). On the dynamics of hIGF-I gene expression in response to elevated temperature, hIGF-I mRNA levels were significantly elevated after at least 2 days of exposure to warm temperature. This validates the concept that hIGF-I gene expressions are sufficiently sensitive to be used as a rapid growth rate indicator for O. niloticus. The hIGF-I levels have a significant positive correlation with specific growth rate (length; r = 0.92), and with condition factor (r = 0.55). On the effect of social stress, differential alterations in growth rates between the dominant and subordinates were observed which was attributed more to behavioral changes as transduced by physiological regulators. The fish's relative position in the social hierarchy was consistently reflected in the levels of hIGF-I mRNA and the eye color pattern. Subordination depressed hIGF-I levels while dominance stimulated it. These findings have shown that hGF-I level remained positively correlated to growth rate as affected by feeding regime, temperature and social stress. This suggests that hIGF-I plays a key role in controlling growth in O. niloticus and indicates that IGF-I mRNA quantification could prove useful for the rapid assessment of growth rate in this species of fish.

Alterações à fisiologia e infeção por Plasmodium berghei do mosquito Anopheles gambiae mediadas pela ativação de recetores GPCR

Dissertação de Mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2015

A novel non-peptidic agonist of the ghrelin receptor with orexigenic activity in vivo

Loss of appetite in the medically ill and ageing populations is a major health problem and a significant symptom in cachexia syndromes, which is the loss of muscle and fat mass. Ghrelin is a gut-derived hormone which can stimulate appetite. Herein we describe a novel, simple, non-peptidic, 2-pyridone which acts as a selective agonist for the ghrelin receptor (GHS-R1a). The small 2-pyridone demonstrated clear agonistic activity in both transfected human cells and mouse hypothalamic cells with endogenous GHS-R1a receptor expression. In vivo tests with the hit compound showed significant increased food intake following peripheral administration, which highlights the potent orexigenic effect of this novel GHS-R1a receptor ligand.

Pituitary Macroadenoma Presenting As A Nasal Tumor: Case Report.

Pituitary macroadenomas are rare intracranial tumors. In a few cases, they may present aggressive behavior and invade the sphenoid sinus and nasal cavity, causing unusual symptoms. In this paper, we report an atypical case of pituitary adenoma presenting as a nasal mass. The patient was a 44-year-old woman who had had amenorrhea and galactorrhea for ten months, with associated nasal obstruction, macroglossia and acromegaly. Both growth hormone and prolactin levels were increased. Magnetic resonance imaging showed a large mass originating from the lower surface of the pituitary gland, associated with sella turcica erosion and tumor extension through the sphenoid sinus and nasal cavity. Histopathological analysis demonstrated a chromophobe pituitary adenoma with densely packed rounded epithelial cells, with some atypias and rare mitotic figures. There was no evidence of metastases. Macroadenoma invading the nasal cavity is a rare condition and few similar cases have been reported in the literature. This study contributes towards showing that tumor extension to the sphenoid sinus and nasopharynx needs to be considered and investigated in order to make an early diagnosis when atypical symptoms like nasal obstruction are present.

Lazer como pratica educativa : as possibilidades para o desenvolvimento humano

Universidade Estadual de Campinas. Faculdade de Educação Física

Survey regional sobre crescimento e desenvolvimento : relações com maturação, sobrepeso e obesidade, nível socioeconômico e desempenho motor

Universidade Estadual de Campinas . Faculdade de Educação Física

Hormônio do crescimento e exercício físico: considerações atuais

Embora o hormônio do crescimento (GH) seja um dos hormônios mais estudados, vários de seus aspectos fisiológicos ainda não estão integralmente esclarecidos, incluindo sua relação com o exercício físico. Estudos mais recentes têm aumentado o conhecimento a respeito dos mecanismos de ação do GH, podendo ser divididos em: 1) ações diretas, mediadas pela rede de sinalizações intracelulares, desencadeadas pela ligação do GH ao seu receptor na membrana plasmática; e 2) ações indiretas, mediadas principalmente pela regulação da síntese dos fatores de crescimento semelhantes à insulina (IGF). Tem sido demonstrado que o exercício físico é um potente estimulador da liberação do GH. A magnitude deste aumento sofre influência de diversos fatores, em especial, da intensidade e do volume do exercício, além do estado de treinamento. Atletas, normalmente, apresentam menor liberação de GH induzida pelo exercício que indivíduos sedentários ou pouco treinados. Evidências experimentais demonstram que o GH: 1) favorece a mobilização de ácidos graxos livres do tecido adiposo para geração de energia; 2) aumenta a capacidade de oxidação de gordura e 3) aumenta o gasto energético.

Effects of trans-10, cis-12 conjugated linoleic acid on gene expression and lipid metabolism of adipose tissue of growing pigs

The objective of the present study was to determine the effects of trans-10, cis-12 conjugated linoleic acid (CLA) in adipose tissue explant cultures of growing pigs on the following responses: lipogenesis (measured as rate of C-14-labeled glucose incorporation over a subsequent 2-h incubation in the presence or absence of insulin), lipolysis (release of non-esterified fatty acid over a 2-h incubation in the presence or absence of isoproterenol), activities of lipogenic enzymes, and mRNA abundance of fatty acid synthase (FAS). Adipose tissue explants from nine growing pigs (78 +/- 3 kg) were cultured in 199 medium with insulin, dexamethasone and antibiotics for 4, 12, 24, and 48 h. The treatments were 1) control: 100 mu M polyvinyl alcohol (PVA); 2) pGH: 100 ng/mL porcine growth hormone (pGH) plus 100 mu M PVA; 3) CLA200: 200 mu M trans-10, cis-12 CLA; 4) CLA50: 50 mu M trans-10, cis-12 CLA, and 5) LA: 200 mu M linoleic acid. Fatty acids were added along with PVA (2: 1), respectively, for 24 h. Explants were collected after each culture period and assayed for lipogenesis. Transcripts of FAS mRNA were quantified by real-time RT-PCR after 24 and 48 h. Lipolysis and activities of FAS, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-malate dehydrogenase were determined after 48 h. As expected, glucose incorporation was decreased (P < 0.05) in response to pGH treatment (positive control). LA had no effect on any parameter evaluated. Treatment with trans-10, cis-12 CLA decreased FAS activity (P < 0.05), but NADPH-generating enzymes were unaffected by treatments. Consistent with reduction in FAS activity, both lipid synthesis and FAS mRNA abundance were reduced with chronic CLA treatment, pGH increased baseline and stimulated lipolysis (P < 0.05) after 48 h of culture, while CLA treatment had no effect on non-esterified fatty acid release. Results of this study showed that trans-10, cis-12 CLA alters lipogenesis but has no effect on lipolysis in cultures of pig adipose tissue.

Latin American Consensus: Children Born Small for Gestational Age

Background: Children born small for gestational age (SGA) experience higher rates of morbidity and mortality than those born appropriate for gestational age. In Latin America, identification and optimal management of children born SGA is a critical issue. Leading experts in pediatric endocrinology throughout Latin America established working groups in order to discuss key challenges regarding the evaluation and management of children born SGA and ultimately develop a consensus statement. Discussion: SGA is defined as a birth weight and/or birth length greater than 2 standard deviations (SD) below the population reference mean for gestational age. SGA refers to body size and implies length-weight reference data in a geographical population whose ethnicity is known and specific to this group. Ideally, each country/region within Latin America should establish its own standards and make relevant updates. SGA children should be evaluated with standardized measures by trained personnel every 3 months during year 1 and every 6 months during year 2. Those without catch-up growth within the first 6 months of life need further evaluation, as do children whose weight is <= -2 SD at age 2 years. Growth hormone treatment can begin in SGA children > 2 years with short stature (< -2.0 SD) and a growth velocity < 25th percentile for their age, and should continue until final height (a growth velocity below 2 cm/year or a bone age of > 14 years for girls and > 16 years for boys) is reached. Blood glucose, thyroid function, HbA1c, and insulin-like growth factor-1 (IGF-1) should be monitored once a year. Monitoring insulin changes from baseline and surrogates of insulin sensitivity is essential. Reduced fetal growth followed by excessive postnatal catch-up in height, and particularly in weight, should be closely monitored. In both sexes, gonadal function should be monitored especially during puberty. Summary: Children born SGA should be carefully followed by a multidisciplinary group that includes perinatologists, pediatricians, nutritionists, and pediatric endocrinologists since 10% to 15% will continue to have weight and height deficiency through development and may benefit from growth hormone treatment. Standards/guidelines should be developed on a country/region basis throughout Latin America.

Actions of angiotensin II and dopamine in the medial preoptic area on prolactin secretion

Dopamine (DA) is known as a primary regulator of prolactin secretion (PRL) and angiotensin II (Ang II) has been recognized as one brain inhibitory factor of this secretion. In this work, estrogen-primed or unprimed ovariectornized rats were submitted to the microinjection of saline or Ang II after previous microinjection of saline or of DA antagonist (haloperidol, sulpiride or SCH) both in the medial preoptic area (MPOA). Our study of these interactions has shown that 1) estrogen-induced PRL secretion is mediated by Ang II and DA actions in the MPOA, i.e. very high plasma PRL would be prevented by inhibitory action of Ang II, while very low levels would be prevented in part by stimulatory action of DA through D-2 receptors, 2) the inhibitory action of Ang II depends on estrogen and is mediated in part by inhibitory action of DA through D, receptors and in other part by inhibition of stimulatory action of DA through D2 receptors.

Decreased fertility in poor responder women is not related to oocyte morphological status

Introduction: In women showing impaired fertility, a decreased response to ovarian stimulation is a major problem, limiting the number of oocytes to be used for assisted reproduction techniques (ART). Despite the several definitions of poor response, it is still a matter of debate whether young poor responder patients also show a decrease in oocyte quality. The objective in this study was to investigate whether poor ovarian response to the superstimulation protocol is accompanied by impaired oocyte quality. Material and methods: This study included 313 patients younger than 35 years old, undergoing intracytoplasmic sperm injection. Patients with four or fewer MII oocytes (poor-responder group, PR, n = 57) were age-matched with normoresponder patients (NR, n = 256). Results: A higher rate of oocyte retrieval and a trend towards an increase in MII oocyte rate were observed in the NR group when compared to the PR group (71.6 +/- 1.1% and 74.1 +/- 1.0% vs. 56.3 +/- 2.9% and 66.5 +/- 3.7%; p < 0.0001 and p = 0.056, respectively). A trend toward increased implantation rates was observed in the NR group when compared to the PR group (44 and 24.5 +/- 2.0% vs. 28.8 and 16.4 +/- 3.9%; p = 0.0305 and p = 0.0651, respectively). Conclusions: Low response to ovarian stimulation is apparently not related to impaired oocyte quality. However, embryos produced from poor responder oocytes show impaired capacity to implant and to carry a pregnancy to term.

The Monocarboxylate Transporter 8 and L-Type Amino Acid Transporters 1 and 2 Are Expressed in Mouse Skeletons and in Osteoblastic MC3T3-E1 Cells

Background: Several plasma membrane transporters have been shown to mediate the cellular influx and/or efflux of iodothyronines, including the sodium-independent organic anion co-transporting polypeptide 1 (OATP1), the sodium taurocholate co-transporting polypeptide (NTCP), the L-type amino acid transporter 1 (LAT1) and 2 (LAT2), and the monocarboxylate transporter 8 (MCT8). The aim of this study was to investigate if the mRNAs of these transporters were expressed and regulated by thyroid hormone (TH) in mouse calvaria-derived osteoblastic MC3T3-E1 cells and in the fetal and postnatal bones of mice. Methods: The mRNA expression of the iodothyronine transporters was investigated with real-time polymerase chain reaction analysis in euthyroid and hypothyroid fetuses and litters of mice and in MC3T3-E1 cells treated with increasing doses of triiodothyronine (T(3); 10(-10) to 10(-6) M) or with 10(-8) M T(3) for 1-9 days. Results: MCT8, LAT1, and LAT2 mRNAs were detected in fetal and postnatal femurs and in MC3T3-E1 cells, while OATP1 and NTCP mRNAs were not. LAT1 and LAT2 mRNAs were not affected by TH status in vivo or in vitro or by the stage of bone development or osteoblast maturation (analyzed by the expression of osteocalcin and alkaline phosphatase, which are key markers of osteoblastic differentiation). In contrast, the femoral mRNA expression of MCT8 decreased significantly during post-natal development, whereas MCT8 mRNA expression increased as MC3T3-E1 cells differentiated. We also showed that MCT8 mRNA was up-regulated in the femur of hypothyroid animals, and that it was down-regulated by treatment with T(3) in MC3T3-E1 cells. Conclusions: This is the first study to demonstrate the mRNA expression of LAT1, LAT2, and MCT8 in the bone tissue of mice and in osteoblast-like cells. In addition, the pattern of MCT8 expression observed in vivo and in vitro suggests that MCT8 may be important to modulate TH effects on osteoblast differentiation and on bone development and metabolism.

Hormonal, metabolic and perceptual responses to different resistance training systems

Aim. The purpose of the present study was to compare the effect of different resistance training systems (Multiple-set [MS] and Pyramid [P]) on hormonal, metabolic and perceptual markers of internal load. Methods. Ten healthy men performed two resistance training sessions (MS and P) which consisted of three exercises (bench press, peck deck and decline bench press) with the same total volume of load lifted. The training sessions were performed 14 days apart and allocated in a counter-balanced order. Hormonal (plasma insulin, growth hormone [GH], testosterone and cortisol) and metabolic (blood glucose and lactate) responses were assessed before and after each exercise bout. Session rating of perceived exertion (session RPE) was taken 30-min following each bout. Results. No difference was observed for session-RPE between P and MS bouts (P>0.05). Plasma GH, cortisol and lactate increased significantly after exercise both bouts (P<0.01), but there were no significant changes between MS and P (P>0.05). Conclusion. It is concluded that the acute bout of resistance exercise following MS and P systems provide similar training strain when the total volume of load lifted is matched.