Stanniocalcin gene expression during mouse urogenital development: a possible role in mesenchymal-epithelial signalling.

Stanniocalcin (STC) is a polypeptide hormone first discovered in fish and more recently in mammals. In mammals, the STC gene is widely expressed and the hormone is involved in a variety of functions, but STC does not normally circulate in the blood. In both kidney and gut, STC regulates phosphate fluxes across the transporting epithelia, whereas in brain it protects neurons against cerebral ischemia and promotes neuronal cell differentiation. However, the gene is most highly expressed in ovary and expression is dramatically up-regulated by both pregnancy and nursing. STC mRNA levels are also high in the developing mouse embryo, but literally nothing is known of the tissue pattern of gene expression. Therefore, the aim of this study was to map the temporal and spatial patterns of gene expression during mouse embryologic development, starting with the urogenital system where the gene is so highly expressed in adults. STC mRNA was evident as early as E10.5 in both the mesonephros and genital ridge. Between E10.5 and 14.5 in developing kidney, STC was produced in undifferentiated mesenchyme cells and sequestered by ureteric bud epithelial cells that did not express the gene but nonetheless contained high levels of STC protein. Thereafter, the distribution pattern resembled that in adults such that gene expression predominated in collecting duct cells, whereas protein was present in most nephron segments. The pattern of gene expression during gonadal development was sexually dimorphic. In males, expression was first evident on E12.5 in interstitial mesenchyme cells surrounding the developing sex cords, whereas the protein accumulated in developing gonocytes within the sex cords that did not express the gene. This pattern became more pronounced over the course of gestation. In contrast, ovarian gene expression was only weakly evident during development. Collectively, the evidence suggests that in addition to its regulatory effects in adults, STC has novel and distinctive roles in the mesenchymal-epithelial interactions that are vital to normal organogenesis.     

The emerging role of the endocannabinoid system in cardiovascular disease

Endocannabinoids are endogenous bioactive lipid mediators present both in the brain and various peripheral tissues, which exert their biological effects via interaction with specific G-protein-coupled cannabinoid receptors, the CB₁ and CB₂. Pathological overactivation of the endocannabinoid system (ECS) in various forms of shock and heart failure may contribute to the underlying pathology and cardiodepressive state by the activation of the cardiovascular CB₁ receptors. Furthermore, tonic activation of CB₁ receptors by endocannabinoids has also been implicated in the development of various cardiovascular risk factors in obesity/metabolic syndrome and diabetes, such as plasma lipid alterations, abdominal obesity, hepatic steatosis, inflammation, and insulin and leptin resistance. In contrast, activation of CB₂ receptors in immune cells exerts various immunomodulatory effects, and the CB₂ receptors in endothelial and inflammatory cells appear to limit the endothelial inflammatory response, chemotaxis, and inflammatory cell adhesion and activation in atherosclerosis and reperfusion injury. Here, we will overview the cardiovascular actions of endocannabinoids and the growing body of evidence implicating the dysregulation of the ECS in a variety of cardiovascular diseases. We will also discuss the therapeutic potential of the modulation of the ECS by selective agonists/antagonists in various cardiovascular disorders associated with inflammation and tissue injury, ranging from myocardial infarction and heart failure to atherosclerosis and cardiometabolic disorders.     

The role of the endocannabinoid system in gametogenesis, implantation and early pregnancy

Maternal use of marijuana, in which the exocannabinoid ⁹-tetrahydrocannabinolis the most active psychoactive ingredient, is known to haveadverse effects on various aspects of reproduction includingovulation, spermatogenesis, implantation and pregnancy duration.Endogenous cannabinoids of which Anandamide is the prototypeare widely distributed in the body especially in the reproductivetract and pregnancy tissues and act through the same receptorsas the receptor as ⁹-tetrahydrocannabinol. Anandamide, has beenreported to have pleiotropic effects on human reproduction andin experimental animal models. It appears to be the importantneuro-cytokine mediator synchronizing the embryo-endometrialdevelopment for timed implantation, the development of the embryointo the blastocyst and transport of the embryo across the fallopiantubes. The mechanisms by which it exerts these effects are unclearbut could be via direct actions on the various sites withinthe reproductive system or its differential actions on vasculartone dependent. In this review article we bring together thecurrent knowledge on the role of endoccanabinoids in reproductionand postulate on the potential mechanisms on how these affectreproduction. In addition, we examine its role on the endotheliumand vascular smooth muscle as a potential mechanism for adversepregnancy outcome.     

GPI-microdomains: a role in signalling via immunoreceptors.

Glycosylphosphatidylinositol (GPI)-anchored proteins and glycosphingolipids are assembled on the leukocyte surface within membrane microdomains, which also accommodate a set of cytoplasmic signalling molecules (Src family kinases, G-proteins, linker proteins). Recent results suggest that these membrane specializations mediate not only signal transduction via GPI-proteins and glycolipids but also play important roles in initiation of signalling via immunoreceptors.     

Integrins: a role as cell signalling molecules.

Integrins form the major family of proteins that mediates cell-matrix interactions. As well as an adhesive function, it is increasingly apparent that integrins can transduce messages via classic signalling pathways and impact upon such fundamental cellular processes as proliferation, apoptosis, differentiation, and motility. Dysregulation of these processes are a feature of many malignancies. Altered integrin expression has been observed in many human tumours, and perturbation of integrin function or expression in experimental systems has demonstrated that altered integrin signalling may directly contribute to the development of the malignant phenotype.     

Immune response: A possible role in the pathophysiology of hemangioma

Hemangioma is a distinct category of benign vascular tumors characterized by presentation within the first weeks of life, rapid growth during the first year and variable degree of spontaneous involution over a period of several years. Recent research reported that CD8+ T cells in hemangiomas, and the endothelia of hemangioma uniquely expressed leukocyte marker FCgammaRII and myeloid cell marker. Presence of high levels of indoleamine 2,3-dioxygenase in proliferating hemangiomas and significantly decreasing during involution was also confirmed. Topical application of imiquimod cream, an immune regulator, to proliferating hemangiomas apparently accelerated regression of the lesions. These findings suggest immune response may be involved in the pathogenesis of hemangioma. The endothelia of hemangioma may express various markers to escape the immune surveillance. An immune response may be one of the mechanisms for hemangioma regression. Strategies with systemically or locally applying immune regulator into the tumor may be an applicable way in accelerating the involution of hemangioma.     

Cardiac arrhythmias: the possible role of the renin-angiotensin system

Activation of the renin-angiotensin system during the process of heart failure may predispose the heart to reentrant malignant arrhythmias by reducing the cell coupling and conduction velocity. Here I discuss the possible role of the renin-angiotensin system on the modulation of cell coupling and impulse propagation with consequent generation of reentrant rhythms. Particular emphasis is given to the effects of angiotensin II on the electrical properties of the failing heart and the beneficial effects of angiotensin-converting enzyme inhibitors and angiotensin II AT1 receptor blockade.     

Is the MHC a general self-recognition system playing a major unifying role in an organism?

From the review of several recent observations of cell-cell interactions, which occur preferentially in autologous or syngeneic situations such as rosettes, adhesion, homing, and contact inhibition, the existence of an active general process of cellular self-recognition, not limited to the immune system, is postulated. This process is MHC associated or dependent, and seems to require an identity of ubiquitous molecules of class I--or other linked gene products at the surface of interacting cells. In contrast, class II molecules are not apparently implicated in general self-recognition. The immune system is regarded as a late evolution from a self-recognition system. It retains the ability of self-evolution, but possesses the exclusive property of active discrimination against foreignness. The astonishing fact that identity of MHC products seems to be needed for recognition is discussed in the context of various possible mechanisms. From immunological and genetical consideration, it is proposed that the genuine biological role of the MHC would be that of a self-recognition and unifying system.     

Hypothesis. Biochemical changes at the menopause: possible role of the central nervous system

Some of the biochemical changes which occur at the menopause can be attributed to an increased rate of loss of bone but others cannot be explained in this way. Data, collected through literature search, are presented which suggest that the rise in plasma phosphate concentration at the menopause is not due primarily to increased breakdown of bone but rather to the following sequence of events: progesterone deficiency----respiratory hypoventilation----mild respiratory acidosis and hypoxia----compensatory metabolic alkalosis----altered carbohydrate metabolism----rise in plasma phosphate concentration. Increases in the concentration of many plasma constituents occur at the menopause, which appear to be due to fluid loss and haemoconcentration. A possible cause of these changes is a reduced secretion of vasopressin by the pituitary gland as a result of oestrogen deficiency. Increases in the fasting urinary excretion of phosphate, sodium and magnesium also occur at the menopause. These changes cannot be attributed to increased bone loss but could be due to the effects of oestrogen deficiency on circadian rhythms in the hypothalamus.     

Deregulation of the hedgehog signalling pathway: a possible role for the PTCH and SUFU genes in human rhabdomyoma and rhabdomyosarcoma development

The naevoid basal cell carcinoma syndrome (NBCCS) is caused by mutations in the hedgehog receptor PTCH gene. It is characterized by developmental defects and a predisposition to the development of certain tumours, such as basal cell carcinoma, medulloblastoma and meningioma, and potentially fetal rhabdomyomas and embryonal rhabdomyosarcomas. This study aimed to analyse PTCH status in an NBCCS patient with fetal rhabdomyoma and to investigate whether deregulation of hedgehog signalling, as shown by altered expression of hedgehog pathway components and/or genetic imbalances, is a general finding in sporadic rhabdomyomas and rhabdomyosarcomas. The NBCCS patient had a novel PTCH germ-line mutation, 1370insT, and developed a fetal rhabdomyoma that harboured a 30 bp in-frame deletion in the second allele resulting in homozygous inactivation of PTCH. Sporadic rhabdomyomas and rhabdomyosarcomas showed overexpression of PTCH (43/43) and GLI1 (41/43) mRNA, as determined by in situ hybridization, indicating ongoing active hedgehog signalling. Immunohistochemical staining revealed a subgroup of fetal rhabdomyomas and embryonal rhabdomyosarcomas (12/34) lacking PTCH immunoreactivity. Four of nine informative fetal rhabdomyomas and embryonal rhabdomyosarcomas showed loss of heterozygosity (LOH) in the PTCH region with two of these (one fetal rhabdomyoma and one embryonal rhabdomyosarcoma) also showing LOH in the SUFU region. These findings suggest that haploinsufficiency for the two tumour suppressor genes PTCH and SUFU, which are both active in the same signalling pathway, may be important for tumour development. Based on our results we propose that the pathogenesis of rhabdomyoblastic tumours, particularly fetal rhabdomyomas and embryonal rhabdomyosarcomas, involves deregulation of the hedgehog signalling pathway.     

Natriuresis of fasting: the possible role of leptin-neuropeptide Y system

We developed a new hypothesis claiming that natriuresis of fasting is not only caused by diminished insulin resistance and hyperinsulinaemia with the subsequent reduction of renal sodium retention but it can also be attributed to the function of the leptin-NPY system. Each element of this concept has been substantiated by convincing experimental evidences as follows:1. Leptin, the adipocyte-derived peptide hormone conveys information to the central nervous system about the size of body energy stores and it reciprocally regulates the hypothalamic expression of NPY, the major mediator of its metabolic and neuroendocrine actions.2. NPY has been demonstrated to be intimately involved in the regulation of renal functions; under various experimental conditions it increased urine flow rate and urinary sodium excretion presumably through stimulating the synthesis and/or release of other natriuretic factors.3. Fasting-induced suppression of tissue expression of leptin mRNA and circulating plasma leptin levels is associated with simultaneous activation of NPY system.4. This sequence of events implies that NPY contributes to natriuresis that occurs in response to fasting.     

Establishment of ionic channels and signalling cascades in the embryonic stem cell-derived primitive endoderm and cardiovascular system

The first organ system to be established in early embryogenesis is the cardiovascular system which develops upon interaction with hypoblastic cells of the primitive endoderm. Here we focus on recent work on embryoid bodies derived from pluripotent embryonic stem (ES) cells. Ca(2+) oscillations and Ca(2+) signalling pathways during the differentiation of primitive endodermal cell layers are reported. Furthermore, the development-dependent expression of ion channels and the buildup of signalling cascades involved in the modulation of voltage-dependent L-type Ca(2+) channels during early cardiomyogenesis and the formation of functional vascular structures in the process of vasculogenesis and angiogenesis are reviewed. We also report on the use of green fluorescent protein reporter gene expression under the control of cardiac-specific promoters, e.g. the human cardiac alpha-actin promoter, which enables the identification and in vivo characterization of cardiomyocytes at very early stages of cardiomyogenesis.     

Recovery of a unique bacterial organism in human middle ear fluid and its possible role in chronic otitis media

The middle ear fluids of 10 children with persistent otitis media with effusion (OME) were found to contain an unclassified, slow-growing, gram-positive organism. Large gram-positive cocci, often present as diplococci or tetrads, were readily seen in each effusion. Culture of the fluid on a blood agar plate required 2 to 5 days of incubation at 37 degrees C and yielded a slow-growing coccus in pure culture in 70% of cases and in mixed culture in 30% of cases. The organism in question was unique and could be distinguished from aerococci, gemellas, enterococci, and micrococci. It grew in 6.5% saline and on bile esculin agar. It did not grow at 45 degrees C or anaerobically. It was uniformly catalase and hippurate positive. It gave negative reactions with tellurite, tetrazolium, and pyruvate and did not utilize any of the carbohydrates tested. Reactions to bile esculin were variable. The episodes of OME associated with the bacterium in question were asymptomatic, had been present from 1 to 8 months, and occurred in children who had previously experienced OME. The middle ear fluids were typically serous or seromucinous and contained inflammatory cells. The data suggest that the gram-positive coccus is a newly described middle ear pathogen and may be responsible, in part, for persistent middle ear effusion. The characteristically slow growth of the organism in vitro could hinder recovery of the organism from clinical specimens and may therefore have prevented its earlier recognition.     

Urocortin 2 and urocortin 3 in endometriosis: evidence for a possible role in inflammatory response

Urocortin 2 (Ucn 2) and urocortin 3 (Ucn 3) are neuropeptides expressed by human endometrium. This study evaluated (i) the expression of Ucn 2 and Ucn 3 mRNA in endometriotic lesions and in endometrium of women with endometriosis; (ii) the effect of Ucn 2 and Ucn 3 on cytokines secretion from cultured endometrial stromal cells. Endometriotic tissue was collected from endometrioma (n=39); endometrial specimens were obtained from women with (n=39) and without (n=41) endometriosis throughout menstrual cycle. Tissue specimens were analysed for Ucn 2 and Ucn 3 mRNA expression and peptide localization; the effects of Ucn 2 or Ucn 3 on tumour necrosis factor (TNF-α) and interleukin (IL-4) secretion from cultured endometrial stromal cells was studied. Ucn 2 and Ucn 3 mRNA expression and localization were assessed by RT-PCR and by immuohistochemistry, respectively; cytokines secretion were measured by ELISA. Results showed that endometriotic tissue expressed both Ucn 2 and Ucn 3, with Ucn 3 expression higher in ectopic than in eutopic endometrium. Endometrial Ucn 2 mRNA expression in controls showed peak values at early proliferative phase, while in endometriotic patients low expression and no significant changes throughout menstrual cycle were observed. Endometrial Ucn 3 mRNA expression was highest in late secretory phase in controls, while in endometriotic patients low levels and no menstrual-cycle-related changes were found. When added to cultured endometrial cell cultures, Ucn 2 significantly increased TNF-α (P<0.01) and IL-4 (P<0.001), while Ucn 3 induced an increase of IL-4 secretion (P<0.01). In conclusion, endometriotic tissue expressed and localized Ucn 2 and Ucn 3; patients with endometriosis showed Ucn 2 and Ucn 3 mRNA expression in eutopic endometrium lower than in control group, with no endometrial cycle-related changes. Ucn 2 and Ucn 3-modulated TNF-α and IL-4 secretion from culture endometrial cells. These data suggest a possible involvement of Ucn 2 and Ucn 3 in the mechanisms of endometriosis.