Showing papers in "Journal of Physiology and Pharmacology in 2008"

Roles of short-chain fatty acids receptors, GPR41 and GPR43 on colonic functions.

Abstract: Short chain fatty acids (SCFAs) are the major anions in the large intestine. They are produced by a bacterial fermentation of dietary fiber. SCFAs are known to have a variety of physiological and pathphysiological effects on intestine. However, the mechanisms by which intraluminal SCFAs are sensed are not known. In 2003, two orphan G protein coupled receptors (GPRs), GPR41 and GPR43, have been cloned and demonstrated to be receptors for SCFAs. Thus, we had attempted to make antibodies raised against GPR43 and GPR41 to elucidate the roles of SCFAs on colonic functions. We have also evaluated the effects of SCFAs on colonic motility to define the physiological roles on luminal SCFAs. In rat and human colon, GPR43 protein was detected by Western blot analysis in extracts of whole wall and separated mucosa, but not in muscle plus submucosa extract. By immunohistochemistry, GPR43 immunoreactivity was localized with enteroendocrine cells expressing peptide YY, whereas 5-HT immunoreactive enteroendocrine cells were not immunoreactive for GPR43. GPR41 immunoreactivity was also found in human colon. In functional studies, propionate and butyrate concentration-dependently (10 microM - 10 mM) induced phasic and tonic contractions in rat colonic circular muscle. The propionate-induced phasic contraction was attenuated by atropine, tetrodotoxin and the 5-HT(4) receptor antagonists SB204070. However, acetate did not induce phasic or tonic contractions. Propionate-induced responses were not observed in mucosal free preparations. The present results suggest that the SCFA-induced physiological effects on colonic functions might be attributable to the activation of SCFA receptors on epithelial cells in the colon.

Endurance training increases plasma brain-derived neurotrophic factor concentration in young healthy men

Abstract: It is believed that brain derived neurotrophic factor (BDNF) plays an important role in neuronal growth, transmission, modulation and plasticity. Single bout of exercise can increase plasma BDNF concentration [BDNF](p) in humans. It was recently reported however, that elevated [BDNF](p) positively correlated with risk factors for metabolic syndrome and type 2 diabetes mellitus in middle age group of subjects. On the other hand it is well established that endurance training decreases the risk of diabetes and development of metabolic syndrome. In the present study we have examined the effect of 5 weeks of moderate intensity endurance training on the basal and the exercise induced changes in [BDNF](p) in humans. Thirteen young, healthy and physically active men (mean +/- S.E: age 22.7 +/- 0.5 yr, body height 180.2 +/- 1.7 cm, body weight 77.0 +/- 2.5 kg, V(O2max) 45.29 +/- 0.93 ml x kg-1 x min(-1)) performed a five week endurance cycling training program, composed mainly of moderate intensity bouts. Before training [BDNF]p at rest have amounted to 10.3 +/- 1.4 pg x ml(-1). No effect of a single maximal incremental cycling up to V(O2max) on its concentration was found (10.9 +/- 2.3 pg x ml(-1), P=0.74). The training resulted in a significant (P=0.01) increase in [BDNF]p at rest to 16.8 +/- 2.1 pg x ml(-1), as well as in significant (P=0.0002) exercise induced increase in the [BDNF](p) (10.9 +/- 2.3 pg x ml(-1) before training vs. 68.4 +/- 16.0 pg x ml(-1) after training). The training induced increase in resting [BDNF](p) was accompanied by a slight decrease in insulin resistance (P=0.25), calculated using the homeostatic model assessment version 2 (HOMA2-IR), amounting to 1.40 +/- 0.13 before and 1.15 +/- 0.13 after the training. Moreover, we have found that the basal [BDNF](p) in athletes (n=16) was significantly higher than in untrained subjects (n=13) (29.5 +/- 9.5 pg x ml(-1) vs. 10.3 +/- 1.4 pg x ml(-1), P=0.013). We have concluded that endurance training of moderate intensity increases both basal as well as the end-exercise [BDNF](p) in young healthy men. This adaptive response, contrariwise to the recent findings in patients with metabolic disorders, was accompanied by a slight decrease in insulin resistance.

Biological role of liver X receptors.

Abstract: Liver X receptors (LXRs) are ligand-activated transcription factors of the nuclear receptor superfamily. There are two LXR isoforms termed alpha and beta which upon activation form heterodimers with retinoid X receptor and bind to LXR response element found in the promoter region of the target genes. Their endogenous agonists include a variety of oxidized cholesterol derivatives referred to as oxysterols. In the recent years LXRs have been characterized as key transcriptional regulators of lipid and carbohydrate metabolism. LXRs were shown to function as sterol sensors protecting the cells from cholesterol overload by stimulating reverse cholesterol transport and activating its conversion to bile acids in the liver. This finding led to identification of LXR agonists as potent antiatherogenic agents in rodent models of atherosclerosis. However, first-generation LXR activators were also shown to stimulate lipogenesis via sterol regulatory element binding protein-1c leading to liver steatosis and hypertriglyceridemia. Despite their lipogenic action, LXR agonists possess antidiabetic properties. LXR activation normalizes glycemia and improves insulin sensitivity in rodent models of type 2 diabetes and insulin resistance. Antidiabetic action of LXR agonists is thought to result predominantly from suppression of hepatic gluconeogenesis. However, recent studies suggest that LXR activation may also enhance peripheral glucose uptake. The purpose of this review is to summarize the present state of knowledge on the physiological and pathophysiological implications of LXRs with the special consideration of their role in lipid and carbohydrate metabolism and associated diseases.

Regulation by exercise of skeletal muscle content of mitochondria and GLUT4.

Abstract: Endurance exercise-training results in an increase in the size and number of mitochondria in the skeletal muscles that are involved in the exercise. In early studies of this phenomenon, long-term training programs of progressively increasing intensity and duration were used. These studies gave the impression that the adaptive increase in mitochondria is a slow process. Recent advances in the understanding of how mitochondrial biogenesis is regulated, have made it possible to study the mechanisms by which exercise regulates mitochondrial biogenesis. These studies have shown that a single bout of exercise induces a rapid increase in mitochondrial biogenesis that is mediated both by activation and by increased expression of a transcription coactivator, peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha). PGC-1alpha docks on and coactivates transcription factors that regulate expression of nuclear genes that encode mitochondrial proteins and also of the nuclear gene that encodes mitochondrial transcription factor A (TFAM). TFAM regulates mitochondrial DNA transcription. Thus, PGC-1alpha regulates the coordinated expression of mitochondrial proteins encoded in both nuclear and mitochondrial genes. In addition to an increase in mitochondrial biogenesis, exercise induces an increase in the GLUT4 isoform of the glucose transporter. This increase in GLUT4 occurs in parallel with, and is mediated by, the same signals and some of the same transcription factors as the increase in mitochondrial biogenesis. Two signals generated during exercise, the increase in cytosolic Ca(2+) and the decrease in high energy phosphates, mediate the activation and increased expression of PGC-1alpha. The purpose of this article is to present an overview of what is known regarding these phenomena.

Physiology and pathophysiology of liver inflammation, damage and repair.

Abstract: The liver is the largest organ of the body. It is located between the portal and the general circulation, between the organs of the gastrointestinal tract and the heart. The main function of the liver is to take up nutrients, to store them, and to provide nutrients to the other organs. At the same time has the liver to take up potentially damaging substances like bacterial products or drugs delivered by the portal blood or microorganisms, which reach the circulation. The liver is not only an important power and sewage treatment plant of the body. In fact, the liver is probably the best example for a cheap recycling system. Both parenchymal and nonparenchymal liver cells participate in the clearance activities. The function of the liver as clearance organ, however, harbors the danger that the substances that should be degraded and/or eliminated lead to tissue damage. Thus, effective defense mechanisms are necessary. Among the nonparenchymal cells Kupffer cells, sinusoidal endothelial cells, and natural killer (NK) lymphocytes exert cellular defense functions for the whole body but also for the liver itself. Furthermore, each cell type of the liver, including the hepatocytes, possesses its own defense apparatus.

Mechanisms for exercise training-induced increases in skeletal muscle blood flow capacity: differences with interval sprint training versus aerobic endurance training.

Abstract: Skeletal muscle blood flow capacity (BFC) is increased by exercise training due to structural vascular remodeling (in the form of angiogenesis of capillaries and remodeling of the arterial tree within skeletal muscle) and/or altered control of vascular resistance. Changes in control can be central or the result of changes in reactivity of arteries and arterioles (due to changes in vascular smooth muscle and/or endothelium). The purpose of this review is to evaluate the relative importance of these mechanisms for increased BFC following interval sprint training (IST) and endurance exercise training (ET). Based on the results discussed herein we conclude that the importance of each of these mechanisms varies throughout muscle tissue due to interactions of muscle fiber-type composition and muscle fiber recruitment patterns during exercise. The distribution of vascular adaptive changes varies with mode of training. For example, IST has been shown to produce the greatest relative increase in contractile activity in fast-twitch, white, skeletal muscle (i.e. white gastrocnemius muscle (Gw) and Gw muscle exhibits the largest increase in oxidative capacity, capillary density, BFC, and changes in vascular cells with IST. In contrast, ET has been shown to produce the greatest relative increase in contractile activity in red gastrocnemius muscle (Gr), and Gr muscle exhibits the largest increase in oxidative capacity, capillary density, and BFC after ET training. Results demonstrate that the increases in BFC are not mediated solely by structural adaptation. Rather, changes in vascular control predominate in Gr and soleus muscle, while increases in arteriolar and capillary density predominate following IST in Gw. Finally, evidence indicates that ET and IST induce non-uniform changes in smooth muscle and endothelium throughout skeletal muscle arteriolar networks.

Thirty four years since the discovery of gastrointestinal melatonin.

Abstract: After the discovery of melatonin in the pineal gland by Lerner and co-workers in 1958, melatonin was also detected in the retina and the human appendix. Later, melatonin was confirmed immunohistologically in all segments of the gastrointestinal tract (GIT), in the guts of bovine embryos and in the GIT of low vertebrates. Melatonin was also confirmed in the pancreas and the hepatobiliary system. Melatonin is produced in the enteroendocrine cells of the GIT mucosa. The concentrations of melatonin in the GIT are 10-100x higher than in the plasma and the total amount of melatonin in the GIT is around 400x higher than the amount of melatonin in the pineal gland. Similar to pineal melatonin, GIT melatonin is a multifunctional compound which exhibits some general as well as some specific effects, depending on the organ and the location of GIT tissue. In the GIT, melatonin exhibits endocrine, paracrine, autocrine and luminal actions. Generally, the episodic secretion of melatonin from the GIT is related to the intake and digestion of food and to the prevention of tissue damage caused by hydrochloric acid and digestive enzymes. Some actions, such as the scavenging of hydroxyl free radicals, immunoenhancement and antioxidant effects are of general nature, whereas others, such as an increase of mucosal blood flow, the reduction of peristalsis and the regulation of fecal water content, are specific to the tubular GIT. Generally, melatonin actions oppose those of serotonin. Laboratory and clinical studies indicate that the utilization of melatonin can prevent or treat pathological conditions such as esophageal and gastric ulcers, pancreatitis, colitis, irritable bowel disease, and colon cancer.

Telomere shortening and ageing of the immune system

Abstract: Telomeres are protein-DNA complexes localized at the ends of linear chromosomes constituted by short, tandem G-rich hexanucleotide repeats and associated proteins. Their length shortens with each cell division and correlates inversely with age. It can be modified by genetic and epigenetic factors, sex hormones, reactive oxygen species and inflammatory reactions. A critical minimum length of telomeres triggers a cell cycle arrest or senescence of the cell. The immune system is highly sensitive to shortening of telomeres as its competence depends strictly on cell renewal and clonal expansion of T- and B-cell populations. Cells of the immune system are unique among normal somatic cells as they can up-regulate telomerase, the telomere extending enzyme, and limit telomere attrition in the process of cell proliferation undergoing in activated cells. Telomere length is highly variable among humans. Lineage-specific telomere shortening with different kinetics of telomere attrition was observed in CD4+, CD8+ T lymphocytes, B lymphocytes, granulocytes, monocytes and NK cell population. Immunosenescence is characterized by a special remodeling of the immune system induced by antigen exposure and oxidative stress. In ageing immune system adaptive immunity deteriorates because of a progressive decline of naive T and B cells and decrease of absolute numbers of T and B lymphocytes. The innate compartment of the immune system is relatively well preserved although some age-dependent alterations can be also observed. Nonagenarians or centenarians represent phenomenon of successful ageing of the immune system as most of their immune parameters are well preserved.

Effects of cigarette smoke on the lung and systemic immunity.

Abstract: The influence of tobacco smoke on human health is still an important problem worldwide. Complex inflammatory processes and changes in the immune system are crucial in the pathogenesis of smoking related disorders like chronic obstructive lung disease (COPD), lung cancer, atherosclerosis. The objective of this review is to present the alterations in the immune system in smokers. The main affected system by cigarette smoke (CS) is the respiratory tract. In bronchial epithelium metaplastic and dysplastic changes are accompanied by elevated expression of adhesion molecules and secretion of many cytokines capable of stimulation immune cells influx. In the population of pulmonary macrophages an elevated proportion of cells, changes in expression surface markers with impaired phagocytic and antigen presenting function are observed. Chronic exposure to CS causes increased production of metalloproteinases (MMP) by macrophages and proteolitic enzymes by neutrophils. These enzymes cause destruction of alveolar wall. Increased apoptosis of lung tissue results in augmentation of foreign material which may play a role of autoantigen and which is a target for cytotoxic/suppressor cells. The role of regulatory T (Treg) cells in this process is recently postulated. Smoking cessation is the most effective method of prophylaxis and treatment of diseases related to tobacco smoking. However many immunological changes in smokers are not completely reversible after quitting smoking.

The pathophysiological hypothesis of homocysteine thiolactone-mediated vascular disease.

Abstract: Accumulating evidence suggests that homocysteine (Hcy) metabolite, the thioester Hcy-thiolactone, plays an important role in atherothrombosis. Hcy-thiolactone is a product of an error-editing reaction in protein biosynthesis which forms when Hcy is mistakenly selected by methionyl-tRNA synthetase. The thioester chemistry of Hcy-thiolactone underlies its ability to from isopeptide bonds with protein lysine residues, which impairs or alters protein's function. Protein targets for the modification by Hcy-thiolactone include fibrinogen, low-density lipoprotein, high-density lipoprotein, albumin, hemoglobin, and ferritin. Pathophysiological consequences of protein N-homocysteinylation include protein and cell damage, activation of an adaptive immune response and synthesis of auto-antibodies against N-Hcy-proteins, and enhanced thrombosis caused by N-Hcy-fibrinogen. Recent development of highly sensitive chemical and immunohistochemical assays has allowed verification of the hypothesis that the Hcy-thiolactone pathway contributes to pathophysiology of the vascular system, in particular of the prediction that conditions predisposing to atherosclerosis, such as genetic or dietary hyperhomocysteinemia, lead to elevation of Hcy-thiolactone and N-Hcy-protein. This prediction has been confirmed in vivo both in humans and in mice. For example, plasma Hcy-thiolactone was found to be elevated 59-72-fold in human patients with hyperhomocysteinemia secondary to mutations in methylenetetrahydrofolate reductase (MTHFR) or cystathionine beta-synthase (CBS) genes. Plasma N-Hcy-protein levels are elevated 24-30-fold in MTHFR- or CBS-deficiency, both in human patients and in mice. Plasma and urinary Hcy-thiolactone and plasma N-Hcy-protein levels are also elevated up to 30-fold in mice fed a hyperhomocysteinemic (1.5% methionine) diet. Furthermore, plasma levels of prothromobogenic N-Hcy-fibrinogen were elevated in human CBS deficiency, which explains increased atherothrombosis observed in CBS-deficient patients. We also observed increased immunohistochemical staining for N-Hcy-protein in aortic lesions from ApoE-deficient mice with hyperhomocysteinemia induced by a high methionine diet, relative to the mice fed a normal chow diet. We conclude that genetic or dietary hyperhomocysteinemia significantly elevates proatherothrombotic metabolites Hcy-thiolactone and N-Hcy-proteins in humans and mice.

Activation of endocannabinoid transmission induces antidepressant-like effects in rats.

Abstract: Recent reports indicate that endocannabinoid (eCB) system may be involved in depression and in the antidepressant-like activity demonstrated in experimental models. The present study examined the effects of the eCB uptake inhibitor 4-hydroxyphenyl-5Z,8Z,11Z,14Z-eicosatetraenamide (AM404; 0.1-3 mg/kg), the fatty acid amide hydrolase (FAAH) inhibitor cyclohexylcarbamic acid 3-carbamoylbiphenyl-3-yl ester (URB597; 0.03-0.3 mg/kg), the cannabinoid CB(1) receptor agonist (-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl) phenyl]-trans-4-(3-hydroxypropyl)-cyclohexanol (CP55,940; 0.03-0.3 mg/kg) and the CB(1) receptor antagonist rimonabant (0.3-3 mg/kg) on immobility time in the forced swim test (FST) in rats. Moreover, the effects of AM404, CP55,940 and URB597 on the antidepressant-like activity of imipramine and citalopram in the FST were also examined. We found that AM404 (0.3-3 mg/kg), CP55,940 (0.1 mg/kg) and URB597 (0.1-0.3 mg/kg) reduced the immobility time of rats, while rimonabant (0.3-3 mg/kg) was inactive in this respect. We also observed that the anti-immobility effects of AM404 (1 mg/kg), CP55,940 (0.1 mg/kg) and URB597 (0.3 mg/kg), but not of imipramine (30 mg/kg), were blocked by rimonabant (3 mg/kg). In another set of experiments we showed that the inactive dose of AM404 (0.1 mg/kg) potentiated the effects of the inactive doses of imipramine (15 mg/kg) or citalopram (30 mg/kg), while CP55,940 (0.03 mg/kg) and URB597 (0.03 mg/kg) enhanced the effect of imipramine only. None of the drugs studied, given alone or in combination, increased the basal locomotor activity of rats. Our results indicate that activation of the eCB system induces antidepressant-like effects in the FST in rats, and that these effects are mediated by CB(1) receptors. Moreover, they also indicate that agents activating eCB transmission enhance the anti-immobility responses to antidepressant drugs.

A postgenomic integrated view of prostaglandins in reproduction: implications for other body systems.

Abstract: Prostaglandins are primary mediators of pain and are involved in pathological conditions such as hypertension, cancer and inflammation but are also needed for normal function of the female reproductive system. This may hold true for other systems because long term use of selective COX-2 inhibitors such as VIOXX and BEXTRA was associated with heart failure, leading to their withdrawal. A thorough study of the contribution of prostaglandins in the regulation of normal body function is clearly needed. A major drawback of the current therapeutic strategies aiming at controlling PGs is that they aim at early steps of biosynthesis thus blocking all PGs, good and bad. However, PGs often work as opposing dyads such as PGI2-TXA2 in the vascular system and PGF2alpha-PGE2 in the female reproductive system. The paradigm thus appears as effecting selective synthesis, transport and action of individual PG isoforms. In this respect, the female reproductive system appears as an ideal study model. Data from human and animal genome projects allowed identifying the corresponding members of the biosynthetic and signal transduction components of the PG system in different animal species. Of particular interest was that PG terminal synthase shared similarities or identity with enzymes previously known for steroid or sugar metabolism and free radical detoxification. We present here an integrated view of PG action based on observations in the female reproductive system, but with potential strategic implications for cardiovascular and metabolic complications.

Molecular targets of (-)-epigallocatechin-3-gallate (EGCG): specificity and interaction with membrane lipid rafts.

Abstract: Proteomic studies on anticancer activity of Green Tea Catechins (specifically EGCG) are suggesting a large set of protein targets that may directly interact with EGCG and alter the physiology of diseased cells, including cancer. Of notice, benign cells are usually left untouched. Lipid rafts have been recently recognized as signal processing hubs and suggested to be involved in drug uptake by means of endocytosis. These findings are suggesting new insights on the molecular mechanisms of anticancer drugs action. In the membrane, EGCG is hijacked by the laminin receptor (LamR), a lipid raft protein. Similar to aplidin and edelfosin, EGCG alters membrane domains composition also preventing EGF binding to EGFR, imerization of EGFR and relocation of phosphorylated EGFR to lipid rafts. In vitro studies have recently shown that EGCG also binds both DNA and RNA in GpC-rich regions. This event may importantly affect genes function. Moreover, EGCG was shown to inhibit telomerase, topoisomerase II and DNA methyltransferase 1 (DNMT1), thus ultimately affecting chromatin maintenance and remodeling. But another important alternative pathway besides interaction with specific proteins may play an important role in EGCG action: direct targeting of bioactive membrane platforms, lipid rafts. Structural alteration of the platforms deeply impact (and often inactivates) important pathways involving MAP kinases. The key issue is that, important and specific differences in lipid rafts composition have been found in transformed versus benign cells and apoptotic versus non-apoptotic cells. We suggest here that the anticancer activity of Green Tea Catechins against different kind of cancers may find an explanation in direct targeting of lipid rafts by EGCG.

Cardiovascular and gastrointestinal toxicity of selective cyclo-oxygenase-2 inhibitors in man.

Abstract: It is well established that the use of traditional nonsteroidal anti-inflammatory drugs (NSAIDs) increase the vulnerability of the gastrointestinal (GI) mucosa for the development of peptic lesions and serious ulcer complications. In addition, selective and traditional NSAIDs have also been associated with increased frequency of cardiovascular toxicity, especially in susceptible patients. The objective of this communication is to provide an overview of the salient GI and cardiovascular (CV) toxicity for these drugs. Traditional NSAIDs inhibit the constitutional cyclooxygenase-1 (COX-1) enzyme responsible for eicosanoids biosynthesis not only in joints, a beneficial effect, but also in the stomach, a detrimental effect. Selective NSAIDs were specifically designed to preferentially inhibit the cyclooxygenase-2 (COX-2), an inducible enzyme mediating the production of inflammatory eicosanoids in the joints but sparing the endogenous protective eicosanoids in the stomach. Selective COX-2 inhibitors (COXIBs) have been shown to possess much improved GI tolerability and reduced GI related adverse events when compared with nonselective COX-1 inhibitors. An unexpected CV toxicity had emerged during the COXIBs post marketing outcome studies. Many subsequent studies were carried out to define the CV risks associated with COXIBs and NSAIDs. All COX inhibitors had shown this CV toxicity. In many clinical studies, rofecoxib use was associated with significantly more elevated CV risk when compared with celecoxib and non selective NSAIDs. The COX inhibitors associated CV toxicity has multiple manifestations, which include the induction of myocardial infarction (MI), edema, thrombosis, blood pressure destabilization and death. Patients at risk of CV disease or with a history of CV disease were the most significant determinants of CV events after receiving COX inhibitors. This CV toxicity not only led to the marketing withdrawal of rofecoxib and valdecoxib but also resulted in more restricted, but essentially identical, product labels in the United States for celecoxib and traditional NSAIDS. This CV toxicity is dose and treatment duration dependent and appears to be compound specific rather than COX specific. Additional comprehensive, long-term, prospective investigations comparing the CV and GI safety profile of marketed NSAIDs against each other and against selective inhibitors are needed to address the controversy of COX inhibitors.

Inhaled insulin--does it become reality?

Abstract: After more than 80 years of history the American and European Drug Agencies (FDA and EMEA) approved the first pulmonary delivered version of insulin (Exubera ® ) from Pfizer/Nektar early 2006. However, in October 2007, Pfizer announced it would be taking Exubera ® off the market, citing that the drug had failed to gain market acceptance. Since 1924 various attempts have been made to get away from injectable insulin. Three alternative delivery methods where always discussed: Delivery to the upper nasal airways or the deep lungs, and through the stomach. From these, the delivery through the deep lungs is the most promising, because the physiological barriers for the uptake are the smallest, the inspired aerosol is deposited on a large area and the absorption into the blood happens through the extremely thin alveolar membrane. However, there is concern about the long-term effects of inhaling a growth protein into the lungs. It was assumed that the large surface area over which the insulin is spread out would minimize negative effects. But recent news indicates that, at least in smokers, the bronchial tumour rate under inhaled insulin seems to be increased. These findings, despite the fact that they are not yet statistical significant and in no case found in a non-smoker, give additional arguments to stop marketing this approach. Several companies worked on providing inhalable insulin and the insulin powder inhalation system Exubera ® was the most advanced technology. Treatment has been approved for adults only and patients with pulmonary diseases (e.g., asthma, emphysema, COPD) and smokers (current smokers and individuals who recently quitted smoking) were excluded from this therapy. Pharmacokinetics and pharmacodynamics of Exubera ® are similar to those found with short-acting subcutaneous human insulin or insulin analogs. It is thus possible to use Exubera ® as a substitute for short-acting human insulin or insulin analogs. Typical side effects of inhaled insulin were coughing, shortness of breath, sore throat and dry mouth. Physical exercise increases the transport of inhaled insulin into the circulation and in consequence the likelihood of hypoglycemia. Other problems were the inability to deliver precise insulin doses, because the smallest blister pack available contained the equivalent of 3 U of regular insulin and this dose would make it difficult for many people using insulin to achieve accurate control, which is the real goal of any insulin therapy. For example, someone on 60 U of insulin per day would lower the blood glucose about 90 mg/dl (5 mmol) per 3 U pack, while someone on 30 U a day would drop 180 mg/dl (10 mmol) per pack. Precise control was not possible, especially compared with an insulin pump that can deliver one twentieth of a unit with precision. Another disadvantage was the size of the device. The Exubera ® inhaler, when closed, was about the size of a 200 ml water glass. It opened to about twice the size for delivery. To our information also other companies (Eli Lilly in cooperation with ALKERMES, Novo Nordisk (AERx ® , Liquid), Andaris (Powder)) stopped further development and it is unclear whether an inhaled form of insulin will ever be marketed, because of the problems that have occurred. Only Mannkind (Technosphere ® , Powder) is still working on a Phase III trial. However, our review will briefly summarize the experience regarding inhalant administration of insulin and will describe potential future developments for this type of therapy focussing on the lung.

Pathophysiology of portal hypertension.

Abstract: In last years significant progress in recognizing mechanisms of portal hypertension pathophysiology was done. However, some unclear topics in this disease still exist. Portal hypertension is primarily caused by the increase in resistance to portal outflow and secondly by an increase in splanchnic blood flow. Portal hypertension is associated with changes in the intrahepatic, systemic, and portosystemic collateral circulation. Alterations in vasoreactivity (vasodilation and vasoconstriction) play a central role in the pathophysiology of portal hypertension by contributing to increased intrahepatic resistance, hyperdynamic circulation, and expansion of the collateral circulation. Among vasoactive substances which are activated in portal hypertension nitric oxide (NO) is considered as the most important vasodilator. Endothelin-1 and cyclooxygenase-derived prostaglandins are the main vasoconstrictor factors. The imbalance between the hyperresponsiveness and overproduction of vasoconstrictors and the hyporesponsiveness and impaired production of vasodilators are the mechanisms responsible of the increased vascular one in the sinusoidal area of the liver. New concepts in the pathophysiology of portal hypertension find the significant role of hepatic stellate cells activated by endothelial factors which cause vascular remodeling as an adaptive response of the portal vessels wall. The most frequent causes of portal hypertension include portal vein thrombosis, storage diseases of the liver, hepatic cirrhosis (independent of etiology), hepatic veins thrombosis and schistosomiasis. Understanding the pathophysiology of portal hypertension could be of great utility in preventing and curing the complications of portal hypertension, such as esophageal varices, hepatic encephalopathy, ascites.

Sirt7-dependent inhibition of cell growth and proliferation might be instrumental to mediate tissue integrity during aging

Abstract: Mammalian sirtuins, Sirt1 ― Sirt7, are recently discovered regulatory proteins, which play decisive roles in cellular metabolism, stress resistance, and proliferation. Sirtuins are homologs of the founder member of the sirtuin family, the yeast Sir2. Sir2 encodes a NAD + -dependent histone deacetylase and its overexpression extends the lifespan through silencing of specific chromatin regions. Lifespan extension by Sir2 homologs was also demonstrated in more complex species such as C. elegans and D. melanogaster. A longevity function has been also postulated for mammalian sirtuins, however definitive proof is still lacking. Here, we have investigated the role of the mouse Sirt7 in the control of cellular growth and proliferation. Using Sirt7 knockout and overexpressing cells we demonstrate an anti-proliferative role of Sirt7. We also show that Sirt7 expression inversely correlates with the tumorigenic potential of several murine cell lines. Considering the known role of Sirt7 as an activator of rDNA transcription we propose that Sirt7 may enable cells to sustain critical metabolic functions by inhibiting cell growth even under severe stress conditions. We conclude, that these Sirt7 functions may improve tissue integrity in aged animals.

Systemic treatment by inhalation of macromolecules--principles, problems, and examples.

Abstract: Aerosol inhalation is an established route of medical administration for the treatment of pulmonary diseases. In contrast, aerosol inhalation for treatment of systemic diseases is a novel therapeutic approach. Clinical use of the latter therapy for many years has been limited by the lack of accuracy, efficiency, and reproducibility of the administered doses. Usually, only a small fraction of inhaled drug reached the target region within the lungs. Further problems were the risk of potential allergic reactions in the respiratory tract and a potential variability of drug absorption from the alveoli into the circulation. These problems have been solved in the last years by modern aerosol delivery systems allowing the production of an aerosol with a defined and optimised aerosol particle size combined with an optimized breathing maneuver and optimization of the efficacy of the technology. Furthermore, there were no observations of relevant allergic reactions after inhalation of systemically active drugs in numerous studies. Studies demonstrated that only a small number of morphological factors influence alveolar drug deposition (e.g., exogen allergic alveolitis, active sarcoidosis, active smoking). In consequence, an increasing number of studies investigated the systemic effect of inhaled high molecular weight substances (e.g., insulin, heparin, interleukin-2) and demonstrated that controlled aerosol therapy may serve as a non-invasive alternative for drug application by means of a syringe. Our review briefly summarizes the mechanisms for pulmonary absorption of macromolecules and gives an overview on prior research in the field of inhalant treatment of systemic diseases.

Crossroads of cytokine signaling - the chase to stop muscle cachexia

Abstract: There is no universal approach to stop muscle cachexia in a number of life-threatening diseases. Accordingly, it is uncertain why the body mass is so critical to keep alive patients with cancer, congestive heart failure (CHF), AIDS or sepsis. At present, it is widely believed that excess muscle wasting diminishes lean body mass to the risky level accompanied by anorexia, anemia, lipolysis, acute phase response and insulin resistance. If missed and/or untreated muscle cachexia inevitably leads to death due to cardiac and respiratory failure (almost one-third of all cancer deaths). This complex metabolic disorder is suited by the elevated levels of inflammatory cytokines (TNF-alpha, IFN-gamma, IL-1-beta, IL-6, IL-2) and low levels of anti-inflammatory/ other cytokines (IL-15, leptin). Concurrently, tissue sensitivity to insulin is considerably reduced. Recent findings indicate that entirely few muscle-specific genes (i.e. MyoD and myosin heavy chain, MyHC) and their products must be targeted to initiate muscle wasting. Muscle atrophy occurs at different levels, starting from repressed gene expression and ended with accelerated protein degradation. Muscle growth (myogenesis) is severely compromised and disruption of sarcomere architecture heralds the proteolysis of contractile apparatus. This review aims to synthesize our present knowledge of intracellular mechanisms and molecular regulation of muscle cachexia with respect to cytokine signaling.

Control of development of gastrointestinal system in neonates

Abstract: Our recent studies of structure and function of gastrointestinal tract mucosa revealed that the domestification of Sus scrofa corresponds with the significant slowing of the organ development. On top of genetic potential, the nutritional factors (or more precisely - lack of certain biologically active substances in the feed of pregnant sows) are responsible. Moreover, feeding neonates with milk replacers instead of mother's milk further slows down the development. This is manifested by reduced mitotic activity in the crypts and enhanced apoptosis of enterocytes. The negative effects consist of slower replacement of fetal type, vacuolated enterocytes to adult type enterocytes, modified profile of brush border enzymes, alterations in intestinal mucosa barrier, higher susceptibility to infectious agents, and many others. On the other hand, farmers in order to intensify the production, shorten the suckling period imposing the neonatal piglets to be weaned at 3-4 weeks of life and even earlier. Altogether, it makes the weaning disorders one of the most important problems in pig husbandry, and the mortality of piglets in the leading pig-producing countries still reaches 10%. A number of strategies have been developed to counteract the post-weaning problems. One of them is to stimulate the development of the gastrointestinal tract of the neonate by supplementation of the sow diet with certain biologically active substances and plants. The other idea is to speed up the postnatal development of the gut mucosa for example by plant lectins. Lessons from pig studies can be also useful in human nutrition and medicine since the development of porcine gastrointestinal tract shows a great similarity to that of humans.

Physiological mediators in nonsteroidal anti-inflammatory drugs (NSAIDs)-induced impairment of gastric mucosal defense and adaptation. Focus on nitric oxide and lipoxins.

Abstract: Prostaglandins mediate various physiological aspects of mucosal defense and the suppression of prostaglandin synthesis in the stomach is a critical event in terms of the development of mucosal injury after NSAID administration. However, it has become clear that other mediators besides prostaglandins can similarly act to protect the stomach from injury. For instance, nitric oxide (NO) released from vascular epithelium, epithelial cells of gastrointestinal tract and sensory nerves can influence many of the same components of mucosal defense as do prostaglandins. Thus, administration of NO in a form of NO-donors exert protective influence on the stomach from the injury that usually occurs when mucosal prostaglandin levels are suppressed. The new class of NO releasing NSAIDs, including NO-aspirin, represent a very promising approach to reducing the toxicity of anti-inflammatory drugs. Lipoxins are another group of lipid mediators that can protect the stomach. Aspirin-triggered lipoxin synthesis, via COX-2, acts to reduce the severity of damage induced by this drug. Lipoxin analogues may prove to be useful for preventing mucosal injury and for modulating mucosal inflammation. Aspirin-triggered lipoxin also seems to play in important role in gastric adaptation during chronic aspirin administration. Suppression of COX-2 activity by selective COX-2 inhibitors abolishes the production of this endogenous gastroprotective substance and diminishes the gastric tolerability of NSAIDS and gastric adaptation to these drugs. This review was designed to give an updated overview on the physiological factors and experimental and clinical attempts that were used or may be used in the future as the therapeutic approach to counteract adverse effects in the stomach associated with NSAID ingestion.

Role of leptin during perinatal metabolic programming and obesity.

Abstract: The incidence of obesity is rapidly increasing all over the world in epidemic proportions.The epidemia now affects young children and accumulative evidences suggest that the origin of the disease may occur during foetal development and early life. This has introduced the concept of "developmental programming" supported by experimental studies in animal models and numerous epidemiological data. This concept supports the idea that nutritional and hormonal status during pregnancy and early life could interfere irreversibly on the development of the organs involved in the control of food intake and metabolism and particularly the hypothalamic structures responsible of the establishment of the ingestive behaviour and regulation of energy expenditure. The mechanisms responsible of this developmental programming remain poorly documented. However, recent research indicate that the adipokine leptin plays a critical role in this programming.

Biological effects of 2-oxoglutarate with particular emphasis on the regulation of protein, mineral and lipid absorption/metabolism, muscle performance, kidney function, bone formation and cancerogenesis, all viewed from a healthy ageing perspective state of the art - review article

Abstract: The fact that men and women are living longer than they have ever done before is something in which we can all rejoice. However, the process of ageing is associated with changes in skeletal, muscular, gastrointestinal, neural hormonal and metabolic processes that seriously affect an individual's performance and quality of life. Indeed, such changes can be contributory to a loss of independence in the elderly. This state-of-the art address highlights the main changes found to occur with ageing whilst simultaneously reporting findings of in vivo and in vitro studies designed to elucidate the potential of the Krebs cycle intermediate - alpha-ketoglutaric acid (AKG) in protecting elderly body systems from failing and degradation. The topics of paramount importance include impaired bone structure and strength, amino acid and mineral absorption, muscle performance, as well as highlighting the role of Krebs cycle intermediates in the debilitating changes that occur with end-stage renal failure and the regulation of the lipid metabolism. Finally, focus will be given to the role of 2-oxoglutarate as a potent protective factor in connection with the development of malignant cells in the body.

Concentration of matrix metalloproteinase-9 in serum of patients with chronic obstructive pulmonary disease and a degree of airway obstruction and disease progression.

Abstract: Chronic obstructive pulmonary disease (COPD) is chronic inflammation leading to irreversible airway obstruction. Previous studies showed increased metalloproteinases (MMP) level, especially MMP-9, as a sign of local inflammation. Up-to-date, only a few studies estimated the MMP-9 serum concentration in COPD with respect to correlation with systemic inflammation. The aim of the present study was to estimate the MMP-9 serum concentration in COPD and to evaluate the correlation between MMP-9 and a degree of airway obstruction in COPD. Twenty three COPD patients and 23 healthy controls were enrolled. In both groups spirometry was performed. MMP-9 concentration in sera taken from both groups was studied using ELISA. We found that COPD patients had increased serum MMP-9 concentration compared with the control group (P=0.0005). In the COPD group, the MMP-9 levels were negatively correlated with FEV1 (P=0.01) and FEV1/FVC (P=0.0002). In conclusion, the results suggest that MMP-9 plays an important role in systemic inflammation in COPD. Higher MMP-9 serum concentration is connected with higher airway obstruction and disease progression.

Regulation of progesterone synthesis and action in bovine corpus luteum.

Abstract: The main function of the corpus luteum (CL) is to synthesize and secrete progesterone (P4), which regulates the duration of the estrous cycle and maintains of pregnancy in many species. Both synthesis and action of this hormone is regulated by many luteotropic and luteolytic factors. Progesterone also affects its own synthesis by regulation of the activity and genes expression of crucial enzymes which control steroidogenesis. The physiological effect of P4 on luteal cells is mediated through the nuclear receptor which occurs in two specific A and B receptor isoforms and also by non-genomic pathways. The nature of non-genomic action of P4 has not been fully understood. It is possible that P4 can temporarily impair binding of oxytocin to its receptor or it can bind one of the three potential membrane receptors. It is assumed that one of these proteins, progesterone receptor membrane component 1 may be involved in regulation of CL function and it can participate in protecting bovine CL against luteolysis. This review summarize the data involving the molecular regulation of P4 synthesis, its intracellular and membrane receptor and the genomic and non-genomic action in the bovine CL.

Studies on antioxidant properties of polyphenol-rich extract from berries of Aronia melanocarpa in blood platelets.

Abstract: The antioxidant properties of extract from berries of Aronia melanocarpa (chokeberry) containing: anthocyanidines, phenolic acids and quercetine glycosides on oxidative/nitrative stress induced by peroxynitrite (ONOO(-), a powerful physiological oxidant, nitrating species and inflammatory mediator) in human blood platelets were studied in vitro. The extract from A. melanocarpa (5 - 50 microg/mL) significantly inhibited platelet protein carbonylation (measured by ELISA method) and thiol oxidation estimated with 5,5'-dithio-bis(2-nitro-benzoic acid) (DTNB) induced by peroxynitrite (0.1 mM) (IC(50)--35 microg/mL for protein carbonylation, and IC(50)--33 microg/mL for protein thiol oxidation). The tested extract only slightly reduced platelet protein nitration (measured by C- ELISA method). The extract also caused a distinct reduction of platelet lipid peroxidation induced by peroxynitrite. Moreover, in our preliminary experiments we observed that the extract (50 microg/mL) reduced oxidative/nitrative stress in blood platelets from patients with breast cancer. The obtained results indicate that in vitro the extract from A. melanocarpa has the protective effects against peroxynitrite-induced oxidative/nitrative damage to the human platelet proteins and lipids. The extract from A. melanocarpa seems to be also useful as an antioxidant in patients with breast cancer.

Training-induced vascular adaptations to ischemic muscle.

Abstract: Peripheral arterial insufficiency is a progressive degenerative disease associated with an increased morbidity and mortality. It decreases exercise tolerance and often presents with symptoms of intermittent claudication. Enhanced physical activity is one of the most effective means of improving the life of affected patients. While this occurs for a variety of reasons, vascular remodeling can be an important means for improved oxygen exchange and blood flow delivery. Relevant exercise-induced signals stimulate angiogenesis, within the active muscle (e.g. hypoxia), and arteriogenesis (enlargement of pre-existing vessels via increased shear stress) to increase oxygen exchange and blood flow capacity, respectively. Evidence from pre-clinical studies shows that the increase in collateral blood flow observed with exercise progresses over time of training, is accompanied by significant enlargement of isolated collateral vessels, and enhances the responses observed with angiogenic growth factors (e.g. VEGF, FGF-2). Thus, enhanced physical activity can be an effective means of enlarging the structure and function of the collateral circuit. Interestingly, disrupting normal NO production (via L-NAME) eliminates this increase in collateral blood flow induced by training, but does not disturb the increase in muscle capillarity within the active muscle. Similarly, inhibiting VEGF receptor kinase activity eliminates the increase in collateral-dependent blood flow, and lessens, but does not eliminate, angiogenesis within the calf muscle. These findings illustrate distinctions between the processes influencing angiogenesis and arteriogenesis. Further, sympathetic modulation of the collateral circuit does not eliminate the increase in collateral circuit conductance induced by exercise training. These findings indicate that structural enlargement of the collateral vessels is essential to realize the increase in collateral-dependent blood flow capacity caused by exercise training. This raises the potential that meaningful vascular remodeling can occur in patients with intermittent claudication who actively participate in exercise training.

Protective and therapeutic effect of heparin in acute pancreatitis.

Abstract: The initiation and progression of acute pancreatitis is associated with disturbances in pancreatic microcirculatory. Microcirculatory disorders contribute to multiorgan dysfunction syndrome in the course of acute pancreatitis. The aim of this study was to determine the influence of heparin administration on the development and the course of ischemia/reperfusion-induced pancreatitis. Methods: Acute pancreatitis was induced in rats by pancreatic ischemia followed by reperfusion. In the first series of studies, heparin was administered 0.5 h before induction of acute pancreatitis and the severity of acute pancreatitis was assessed after 6-h reperfusion. In the second series of studies, heparin was administered twice a day, starting 24 h after the initiation of reperfusion. In both series of studies, heparin was administered subcutaneously at the dose of 150 U/kg. Results: Treatment with heparin, before induction of pancreatitis, inhibits the development of morphological signs of acute pancreatitis and reduced the pancreatitis-evoked increase in plasma level of pancreatic enzymes and pro-inflammatory interleukin-1b. These effects have been accompanied with improvement of pancreatic blood flow, pancreatic DNA synthesis and reduction in plasma concentration of D-dimer. Administration of heparin after induction of acute pancreatitis accelerates normalization of pancreatic histology, and reduces biochemical markers of the severity of acute pancreatitis. These effects have been accompanied with the improvement of pancreatic circulation, increase in APTT and reduction in plasma D-dimer level. Conclusions: Treatment with heparin inhibits the development of ischemia/reperfusion-induced pancreatitis and accelerates pancreatic regeneration in the course of this disease.

Turning down lipid oxidation during heavy exercise--what is the mechanism?

Abstract: A high potential for lipid oxidation is a sign of metabolic fitness and is important not only for exercise performance but also for health promotion. Despite considerable progress during recent yea ...

Modulatory effect of ghrelin in prepubertal porcine ovarian follicles.

Abstract: Ghrelin is a novel growth hormone-releasing peptide, originally identified in rat stomach as an endogenous ligand of the growth hormone secretagogue receptor. Ghrelin is an important regulator of growth hormone secretion, food intake, and reproductive function. This study investigates whether or not ghrelin can modulate prepubertal pig ovary function, which was measured as ovarian estradiol secretion, aromatase activity, cell proliferation, and apoptosis. To investigate this, ovarian cells were co-cultured with four different doses of ghrelin (100, 250, 500, and 1000 pg/ml) for 48 h. Culture media samples were collected, and estradiol levels were determined, while aromatase expression was measured in the cultured cells. Cell apoptosis was measured by determination of caspase-3 activity, DNA fragmentation and TUNEL assay. Ghrelin in 250 and 500 pg/ml doses stimulated estradiol secretion. At all doses ghrelin stimulated aromatase activity and protein expression. Moreover, ghrelin increased cell proliferation and decreased apoptosis. This study provides novel evidence that ghrelin has a modulatory effect in the ovary. We suggest two mechanisms that explain how ghrelin acts on estradiol secretion: 1) ghrelin directly influences aromatase activity and protein expression; 2) ghrelin stimulates cell proliferation and antiapoptotic actions.