Role of Endothelial Kinin B1 Receptor on the Membrane Potential of Transgenic Rat Aorta.

The kinin receptors are classically involved in inflammation, pain and sepsis. The effects of the kinin B1 receptor agonist des-Arg9-bradykinin (DBK) and lipopolysaccharide (LPS) were investigated by comparing the membrane potential responses of aortic rings from transgenic rats overexpressing the kinin B1 receptor (B1R) in the endothelium (TGR(Tie2B1)) and Sprague Dawley (SD) rats. No difference in the resting membrane potential in the aorta's smooth muscle from the transgenic and SD rats was observed. The aorta rings from SD rats hyperpolarized only to LPS but not to DBK, whereas the aorta rings from TGR(Tie2B1) responded by the administration of both drugs. DBK and LPS responses were inhibited by the B1 receptor antagonist R715 and by iberiotoxin in both cases. Thapsigargin induced a hyperpolarization in the smooth muscle of SD rats that was not reversed by R715, but was reversed by iberiotoxin and this hyperpolarization was further augmented by DBK administration. These results show that the model of overexpression of vascular B1 receptors in the TGR(Tie2B1) rats represent a good model to study the role of functional B1 receptors in the absence of any pathological stimulus. The data also show that KCa channels are the final mediators of the hyperpolarizing responses to DBK and LPS. In addition, we suggest an interaction between the B1R and TLR4, since the hyperpolarization induced by LPS could be abolished in the presence of R715.

Cardiac morphofunctional characteristics of transgenic rats with overexpression of the bradykinin B1 receptor in the endothelium.

Our aim was to evaluate whether endothelial overexpressing of the bradykinin B1 receptor could be associated with altered left ventricular and myocardial performance. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function in Sprague Dawley transgenic rats overexpressing the endothelial bradykinin B1 receptor (Tie2B1 rats). The myocardial inotropism was evaluated on papillary muscles contracting in vitro. In Tie2B1 animals, an enlarged left ventricular cavity and lower fractional shortening coupled with a lower rate of pressure change values indicated depressed left ventricular performance. Papillary muscle mechanics revealed that both Tie2B1 and wild-type rat groups had the same contractile capacities under basal conditions; however, in transgenic animals, there was accentuated inotropism due to post-pause potentiation. Following treatment with the Arg(9)-BK agonist, Tie2B1 papillary muscles displayed a reduction in myocardial inotropism. Endothelial B1 receptor overexpression has expanded the LV cavity and worsened its function. There was an exacerbated response of papillary muscle in vitro to a prolonged resting pause, and the use of a B1 receptor agonist impairs myocardial inotropism.

Sex-dependent differences in renal angiotensinogen as an early marker of diabetic nephropathy.

AIM: The renal renin-angiotensin system (RAS) has been implicated in the pathogenesis of diabetic nephropathy. The aim of this study was to investigate sex differences in renal renin-angiotensin system (RAS) and the roles of androgens in diabetes-associated renal injury. METHODS: Renal injury and fibrosis were studied in streptozotocin-induced diabetic rats by albuminuria and by gene expression of collagen I and fibronectin. RAS was investigated by analysing the plasma angiotensinogen (AOGEN) and renin activity (PRA) and their renal gene expression. Also, a group of diabetic rats was treated with the anti-androgen flutamide. RESULTS: Albuminuria was significantly lower in diabetic females than in males (1.2 [0.8-1.5] versus 4.4 [2.2-6.1] mg/24 h, data are median [IQR] values, P < 0.05). Renal AOGEN mRNA levels were increased by diabetes in males (8.1 ± 0.8% in diabetes versus 0.8 ± 0.2% in control, P < 0.001) but not in females (1.0 ± 0.1% in diabetes versus 0.8 ± 0.1% in control, P > 0.05), as were collagen I and fibronectin mRNAs. Furthermore, AOGEN mRNA levels were strongly correlated with albuminuria (Spearman r = 0.64, 95% [CI] 0.36-0.81, P < 0.0001). Diabetes decreased PRA, renal renin mRNA and plasma AOGEN in both females and males. Anti-androgen treatment decreased albuminuria only in diabetic males without affecting the endocrine or renal RAS. CONCLUSIONS: These data indicate that renal but not hepatic AOGEN or renin is positively associated with diabetic albuminuria and contribute to the sex-dependent differences in renal injury. Androgens may contribute to albuminuria in male independently of the RAS.

Evidence for the participation of kinins in Freund's adjuvant-induced inflammatory and nociceptive responses in kinin B1 and B2 receptor knockout mice.

Experiments were designed to investigate the role of kinin B(1) and B(2) receptors in Freund's adjuvant (CFA)-induced inflammation and nociception responses by the use of B(1) and B(2) null mutant mice. Intradermal (i.d.) injection of CFA produced time-dependent and marked hyperalgesic responses in both ipsilateral and contralateral paws of wild-type mice. Gene disruption of the kinin B(2) receptor did not interfere with CFA-induced hyperalgesia, but ablation of the gene of the B(1) receptor reduced the hyperalgesia in both ipsilateral (48+/-13%, at 12 h) and contralateral (91+/-22%, at 12 h) paws. Treatment of wild-type mice with the selective B(1) antagonist des-Arg(9)-[Leu(8)]-BK (150 nmol/kg, s.c.) reduced CFA-evoked thermal hyperalgesia, to an extent which was similar to that observed in mice lacking kinin B(1) receptor. I.d. injection of CFA produced a time-related and long-lasting (up to 72 h) increase in paw volume in wild-type mice. A similar effect was observed in B(1) knockout mice. In mice lacking B(2) receptor, the earlier stage of the CFA-induced paw oedema (6 h) was significantly greater compared with the wild-type animals, an effect which was almost completely reversed (76+/-5%) by des-Arg(9)-[Leu(8)]-BK. This data demonstrates that kinin B(1) receptor, but not B(2) receptor, exerts a critical role in controlling the persistent inflammatory hyperalgesia induced by CFA in mice, while B(2) receptor appears to have only a minor role in the amplification of the earlier stage of CFA-induced paw oedema formation. The results of the present study, taken together with those of previous studies, suggest that B(1) receptor antagonists represent a potential target for the development of new drugs to treat persistent inflammatory pain.

Interactions between angiotensin-(1-7), kinins, and angiotensin II in kidney and blood vessels.

The heptapeptide angiotensin (Ang)-(1-7) is currently considered one of the biologically active end products of the renin-angiotensin system. The formation of Ang-(1-7) by pathways independent of Ang II generation, the selectivity of its actions, and its peculiar property of exhibiting effects that are partially opposite of those of the parent compound, Ang II, confer a unique biochemical and functional profile to this peptide. In this article, we will review novel aspects of the biological actions of Ang-(1-7), dealing with its interaction with Ang II and kinins, especially in the kidney and blood vessels.

Altered neutrophil homeostasis in kinin B1 receptor-deficient mice.

The kallikrein-kinin system is activated during inflammation and plays a major role in the inflammatory process. One of the main mechanisms of kinin action includes the modulation of neutrophil function employing both receptors for kinins, B1 and B2. In this report we show by the use of B1 receptor-deficient mice that neutrophil migration in inflamed tissues is dependent on kinin B1 receptors. However, there is no change in circulating leukocyte number and composition after genetic ablation of this receptor. Furthermore, apoptosis of neutrophils necessary for the resolution of persistent inflammatory processes is impaired in mice lacking the B1 receptor. We also show that this receptor is expressed on neutrophils, thus it may be directly involved in the induction of apoptosis in these cells after prolonged activation at inflamed sites. In conclusion, our data show that the kinin B1 receptor modulates migration and the life span of neutrophils at sites of inflammation and may be therefore an important drug target in the therapy of inflammatory diseases.

Análisis comparativo in vitro de las propiedades físico-mecánicas de dos resinas compuestas de reciente aparición v/s su antecesora / In vitro comparative study of physical-mechanical properties of 2 new composites versus the olders

Se realizó un estudio experimental para comparar propiedades físicas y mecánicas de la resina compuesta Z100 y sus dos sucesoras: P60 y Z250. Se confeccionaron 30 probetas en total para realizar las pruebas de: Resistencia a la tensión diametral, translucidez, profundidad de polimerización, tiempo de trabajo útil. Una vez realizadas las pruebas se concluyó que el material P60 registra la mayor profundidad de polimerización y el material Z250 presenta la mayor resistencia a la tensión diametral, así como la mayor translucidez. En promedio, todos los valores de las nuevas resinas compuestas fueron superiores a Z100, siendo o no estadísticamente significativas

Angiotensin peptides acting at rostral ventrolateral medulla contribute to hypertension of TGR(mREN2)27 rats.

We have previously demonstrated that microinjections of the selective angiotensin-(1-7) [ANG-(1-7)] antagonist, A-779, into the rostral ventrolateral medulla (RVLM) produces a significant fall in mean arterial pressure (MAP) and heart rate (HR) in both anesthetized and conscious rats. In contrast, microinjection of angiotensin II (ANG II) AT(1) receptor antagonists did not change MAP in anesthetized rats and produced dose-dependent increases in MAP when microinjected into the RVLM of conscious rats. In the present study, we evaluated whether endogenous ANG-(1-7) and ANG II acting at the RVLM contribute to the hypertension of transgenic rats harboring the mouse renin Ren-2 gene, TGR(mREN2)27. Unilateral microinjection of A-779 (0.1 nmol) produced a significant fall in MAP (-25 +/- 5 mmHg) and HR (-57 +/- 20 beats/min) of awake TGR rats. The hypotensive effect was greater than that observed in Sprague-Dawley (SD) rats (-9 +/- 2 mmHg). Microinjection of the AT(1) antagonist CV-11974 (0.2 nmol) produced a fall in MAP in TGR rats (-14 +/- 4 mmHg), contrasting with the pressor effect observed in SD rats (33 +/- 9 mmHg). These results indicate that endogenous ANG-(1-7) exerts a significant pressor action in the RVLM, contributing to the hypertension of TGR(mREN2)27 transgenic rats. The role of ANG II at the RVLM seems to be dependent on its endogenous level in this area.

Altered heart rate and blood pressure variability in mice lacking the Mas protooncogene.

Heart rate variability is a relevant predictor of cardiovascular risk in humans. A significant genetic influence on heart rate variability is suggested, although the genes involved are ill-defined. The Mas-protooncogene encodes a G-protein-coupled receptor with seven transmembrane domains highly expressed in testis and brain. Since this receptor is supposed to interact with the signaling of angiotensin II, which is an important regulator of cardiovascular homeostasis, heart rate and blood pressure were analyzed in Mas-deficient mice. Using a femoral catheter the blood pressure of mice was measured for a period of 30 min and 250 data values per second were recorded. The mean values and range of heart rate and blood pressure were then calculated. Neither heart rate nor blood pressure were significantly different between knockout mice and controls. However, high resolution recording of these parameters and analysis of the data by non-linear dynamics revealed significant alterations in cardiovascular variability in Mas-deficient animals. In particular, females showed a strong reduction of heart rate variability. Furthermore, the data showed an increased sympathetic tone in knockout animals of both genders. The marked alterations detected in Mas-deficient mice of both genders suggest that the Mas-protooncogene is an important determinant of heart rate and blood pressure variability.

Molecular biology of the kallikrein-kinin system: from structure to function

The participation of the kallikrein-kinin system, comprising the serine proteases kallikreins, the protein substrates kininogens and the effective peptides kinins, in some pathological processes like hypertension and cardiovascular diseases is still a matter of controversy. The use of different experimental set-ups in concert with the development of potent and specific inhibitors and antagonists for the system has highlighted its importance but the results still lack conclusivity. Over the last few years, transgenic and gene-targeting technologies associated with molecular biology tools have provided specific information about the elusive role of the kallikrein-kinin system in the control of blood pressure and electrolyte homeostasis. cDNA and genomic sequences for kinin receptors B2 and B1 from different species were isolated and shown to encode G-protein-coupled receptors and the structure and pharmacology of the receptors were characterized. Transgenic animals expressing an overactive kallikrein-kinin system were established to study the cardiovascular effects of these alterations and the results of these investigations further corroborate the importance of this system in the maintenance of normal blood pressure. Knockout animals for B2 and B1 receptors are available and their analysis also points to the role of these receptors in cardiovascular regulation and inflammatory processes. In this paper the most recent and relevant genetic animal models developed for the study of the kallikrein-kinin system are reviewed, and the advances they brought to the understanding of the biological role of this system are discussed.

Transgenic animal models for the functional analysis of vasoactive peptides.

The interplay of vasoactive peptide systems is an essential determinant of blood pressure regulation in mammals. While the endothelin and the renin-angiotensin systems raise blood pressure by inducing vasoconstriction and sodium retention, the kallikrein-kinin and the natriuretic-peptide systems reduce arterial pressure by eliciting vasodilatation and natriuresis. Transgenic technology has proven to be very useful for the functional analysis of vasoactive peptide systems. As an outstanding example, transgenic rats overexpressing the mouse Ren-2 renin gene in several tissues become extremely hypertensive. Several other transgenic rat and mouse strains with genetic modifications of components of the renin-angiotensin system have been developed in the past decade. Moreover, in recent years gene-targeting technology was employed to produce mouse strains lacking these proteins. The established animal models as well as the main insights gained by their analysis are summarized in this review.

Molecular biology of the kallikrein-kinin system: from structure to function.

The participation of the kallikrein-kinin system, comprising the serine proteases kallikreins, the protein substrates kininogens and the effective peptides kinins, in some pathological processes like hypertension and cardiovascular diseases is still a matter of controversy. The use of different experimental set-ups in concert with the development of potent and specific inhibitors and antagonists for the system has highlighted its importance but the results still lack conclusivity. Over the last few years, transgenic and gene-targeting technologies associated with molecular biology tools have provided specific information about the elusive role of the kallikrein-kinin system in the control of blood pressure and electrolyte homeostasis. cDNA and genomic sequences for kinin receptors B2 and B1 from different species were isolated and shown to encode G-protein-coupled receptors and the structure and pharmacology of the receptors were characterized. Transgenic animals expressing an overactive kallikrein-kinin system were established to study the cardiovascular effects of these alterations and the results of these investigations further corroborate the importance of this system in the maintenance of normal blood pressure. Knockout animals for B2 and B1 receptors are available and their analysis also points to the role of these receptors in cardiovascular regulation and inflammatory processes. In this paper the most recent and relevant genetic animal models developed for the study of the kallikrein-kinin system are reviewed, and the advances they brought to the understanding of the biological role of this system are discussed.

Transcriptional regulatory elements in the rat bradykinin B2 receptor gene.

In an attempt to elucidate the mechanisms underlying the regulation of bradykinin B2 receptor gene expression, the molecular structure of the rat gene including the 5'-flanking region was characterized (J. Biol. Chem. 269: 26920-26925, 1994). In this study we show that the gene spans about 32 kb, including a long first intron of 25 kb. The promoter region drives reporter gene expression in NG108-15 neuroglioma cells, and its expression is upregulated by cAMP, bradykinin, phorbol esters and by coexpression of an activated ras oncogene but not by dexamethasone.

Molecular cloning and functional characterization of a mouse bradykinin B1 receptor gene.

The gene encoding a putative mouse bradykinin B1 receptor was cloned from a genomic library by low stringency screening. Analysis of two isolated clones revealed a region which contains an open reading frame uninterrupted by introns and encodes a 334 amino acid protein, which exhibits seven potential transmembrane domains and is 68% identical to the human and rabbit bradykinin B1 receptors. Lipopolysaccharide-treatment induces B1 receptor transcripts in the heart, liver, and lung. Stable expression of the coding region in COS-7 cells resulted in high levels of binding sites for the specific B1 ligand des-ARG10 kallidin (Kd = 1.3 nM; Bmax = 51 fmol/mg protein). The rank order of affinity of the receptor for the agonists and antagonists was: des-Arg9BKdes-Arg9Leu8BKdes- Arg10kallidin >> Hoe-140=bradykinin. Functional coupling of the cloned receptor was demonstrated by the dose-dependent effects of des-Arg(9)BK on the extracellular acidification rate in stably transfected COS-7 cells. This effect was not produced by bradykinin and could be blocked by the B1 antagonist des-Arg9Leu8BK.

Molecular structure and expression of rat bradykinin B2 receptor gene. Evidence for alternative splicing.

Bradykinin is a potent vasodilatory peptide hormone involved in a broad range of physiological actions. While it acts through at least two types of receptors which are named B1 and B2, most of its effects are mediated via activation of the B2 receptor. The gene for this receptor was isolated from a rat genomic library and shown to span more than 28 kilobases, including four introns. The relative positions of the exons were mapped and all exons, intron-exon boundaries, and 5'- and 3'-flanking regions were sequenced. While the 5'-untranslated region of the mRNA is distributed on all four exons, the coding and the 3'-untranslated region are located entirely on the fourth exon. Characterization of the region upstream to the transcriptional start site detected by primer extension analysis shows that the bradykinin B2 receptor promoter contains no typical TATA or CCAAT boxes. Nevertheless, the promoter sequence was shown to be functional in NG108-15 cells transfected with a construct bearing 1.1 kilobases of 5'-flanking sequence fused to a luciferase reporter gene. Reverse transcription-polymerase chain reaction analysis detected two different bradykinin B2 receptor mRNAs containing or lacking exon 3 in all rat tissues tested, providing evidence for alternative splicing of the 5'-untranslated sequence.

Permeabilidad de barnices cavitarios: estudio in vitro / Permeability of cavity varnishes: in vitro study

Los varnices cavitarios vienen usándose hace tiempo en la profesión odontológica en cavidades operatorias de amalgamas, para disminuir la infiltración marginal debido a la mala adaptación inicial de ellas, y evitar la tinción del diente por la corrosión del metal. Se estudiaron 3 barnices (Copalite, Derfla, Silicate varnish y barniz cavitario Hertz), determinñandose la permeabilidad de ellos a un colorante (azul de metileno 1 por ciento en solución acuosa) medida a la 1ª hora de su aplicación en cavidades simuladas en yeso extraduro saturado con humedad; el grado de permeabilidad fue determinado analizando la penetración del colorante medida en superficie, para cada tipo de material y un grupo control sin barniz. Los valores promedio en mm² de área de infiltración a la 1ª hora fueron de 77.7 para Derfla, 115.6 para Hertz, 127.8 para Copalite, y 127.2 para el grupo Control, encontrándose diferencias estadísticamente significativas entr Derfla y los otros grupos

The international transfer of medical technology--an analysis and a proposal for effective monitoring.

The international transfer of medical technology to the developing countries occurs at four levels--medical education, research, and missions; multinational corporate transactions; technical assistance projects sponsored by the World Health Organization; and bilateral foreign aid programs. In this article, a proposal is made for effective monitoring of international medical technology transfer through political and legal means, including a specific code of conduct for corporations engaged in medical technology transfer. The development of "intermediate health technologies" along the lines suggested by E. F. Schumacher, and the advantages of such an innovation in terms of population issues and economic development are also discussed.

Breast-feeding: the role of multinational corporations in Latin America.

The decline in birthrates in the developed countries of the world has forced multinational corporations engaged in the production of infant formula to seek out new markets in the developing countries, where burgeoning population rates potentially guarantee the long-term profitability of these corporations. This development, ostensibly benign and nutritionally advantageous to infants in developing countries, has serious public health consequences, due to the high relative cost of purchased formula and the paucity of hygienic facilities essential to the sterile preparation of bottle formula. This paper delineates in detail economic and contraceptive advantages of breast-feeding, and examines the role of health personnel and multinational advertising techniques which have catalyzed the decline in breast-feeding. In addition, the paper focuses on the question of cultural imperialism and current efforts to regulate the multinational firms through both United Nations groups and stock-holders' suits. Finally, some suggestions are made concerning ameliorative public policy approaches to the breast-feeding controversy.

PIP: The role of multinational corporations producing infant formula in contributing to the decline of breast-feeding in Latin America is attacked. Breast-feeding has declined dramatically in developing countries during the past 30 years, not only because mothers work but also because bottle feeding is seen as a status symbol. Breast-feeding is seen as backward and failure of lactation is a response to the stress of urbanization. The advantages of breast feeding are summarized. The spread of manufacturers of infant formulas into Latin America is documented. Both advertising in the media and health professionals tend to turn mothers away from breast-feeding. This not only affects infant health adversely since most of these mothers do not have the experience or facilities to bottle feed properly, it affects birthrates by eliminating the lactational amenorrhea which is so important for birth spacing in poor countries. Health professionals need to be aware of this threat and information programs for women must be developed to counteract the advertising of the multinational corporations.