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L Sanz

Publications and source records attributed to L Sanz.

At least 91 records · Page 5Linked to original sources
PubMed1993

Inhibition of protein kinase C zeta subspecies blocks the activation of an NF-kappa B-like activity in Xenopus laevis oocytes.

Nuclear factor kappa B (NF-kappa B) plays a critical role in the regulation of a large variety of cellular genes. However, the mechanism whereby this nuclear factor is activated remains to be determined. In this report, we present evidence that in oocytes from Xenopus laevis, (i) ras p21- and phospholipase C (PLC)-mediated phosphatidylcholine (PC) hydrolysis activates NF-kappa B and (ii) protein kinase C zeta subspecies is involved in the activation of NF-kappa B in response to insulin/ras p21/PC-PLC. Thus, the microinjection of either ras p21 or PC-PLC, or the exposure of oocytes to insulin, promotes a significant translocation to the nucleus of an NF-kappa B-like activity. This effect is not observed when oocytes are incubated with phorbol myristate acetate or progesterone, both of which utilize a ras p21-independent pathway for oocyte activation. These data strongly suggest a critical role of the insulin/ras p21/PC-PLC/protein kinase C zeta pathway in the control of NF-kappa B activation.

Amino Acid Sequence↗
PubMed1993

A dominant negative protein kinase C zeta subspecies blocks NF-kappa B activation.

Nuclear factor kappa B (NF-kappa B) plays a critical role in the regulation of a number of genes. NF-kappa B is a heterodimer of 50- and 65-kDa subunits sequestered in the cytoplasm complexed to inhibitory protein I kappa B. Following stimulation of cells, I kappa B dissociates from NF-kappa B, allowing its translocation to the nucleus, where it carries out the transactivation function. The precise mechanism controlling NF-kappa B activation and the involvement of members of the protein kinase C (PKC) family of isotypes have previously been investigated. It was found that phorbol myristate acetate, (PMA) which is a potent stimulant of phorbol ester-sensitive PKC isotypes, activates NF-kappa B. However, the role of PMA-sensitive PKCs in vivo is not as apparent. It has recently been demonstrated in the model system of Xenopus laevis oocytes that the PMA-insensitive PKC isotype, zeta PKC, is a required step in the activation of NF-kappa B in response to ras p21. We demonstrate here that overexpression of zeta PKC is by itself sufficient to stimulate a permanent translocation of functionally active NF-kappa B into the nucleus of NIH 3T3 fibroblasts and that transfection of a kinase-defective dominant negative mutant of zeta PKC dramatically inhibits the kappa B-dependent transactivation of a chloramphenicol acetyltransferase reporter plasmid in NIH 3T3 fibroblasts. All these results support the notion that zeta PKC plays a decisive role in NF-kappa B regulation in mammalian cells.

3T3 Cells↗
PubMed1993

Effects of L-arginine analogues in isolated cat cerebral arteries.

The possible contribution of nitric oxide (NO) to the endothelium-dependent relaxation of isolated cat cerebral arteries was studied by examining the effects of the L-arginine (L-ARG) analogues L-canavanine and NG-nitro-L-arginine (L-NOARG) on acetylcholine-induced relaxation. L-canavanine (100 microM) as well as L-NOARG (10 microM) decreased significantly the relaxant response of acetylcholine, their effect being significantly reversed by L-arginine (10 microM) but not by D-arginine (10 microM). In resting conditions, L-NOARG (10 microM) elicited a contraction of 314 +/- 42 mg in arteries endowed with endothelium that was significantly diminished by endothelium removal to 88 +/- 35 mg, and by (10 microM) L-arginine to 135 +/- 54 mg. L-canavanine (100 microM) induced contractions in arteries with and without endothelial cells which were not statistically different. The results suggest that the endothelium of cat cerebral arteries has the ability to synthesize nitric oxide from L-arginine and to release it, even in the absence of a stimulus such as that of acetylcholine. L-NOARG seems to be a specific and powerful inhibitor of nitric oxide synthesis.

Acetylcholine↗
PubMed1992

The complete primary structure of the boar spermadhesin AQN-1, a carbohydrate-binding protein involved in fertilization.

Gamete recognition and adhesion are essential steps in the complex process of fertilization. In mammals and in other species, increasing evidence indicates that carbohydrate-binding proteins on the sperm surface play a pivotal role as counter-receptors for certain oligosaccharide moieties attached to the oocyte zona pellucida glycoproteins. Although different sperm-associated zona-pellucida-binding proteins have been identified in a number of species, few of them have been isolated and structurally characterized. In this paper we report the primary structural characterization of AQN-1, a 12-kDa boar-sperm-associated carbohydrate-binding and zona-pellucida-binding protein. The molecular mass of AQN-1 was determined by time-of-flight plasma-desorption mass spectrometry. Determination of its amino acid sequence and location of disulphide bridges were accomplished by a combination of proteochemical and mass spectrometric methods. The primary structure of AQN-1 failed to show any significant similarity to the protein structures deposited with the Martinsried Institute for Protein Sequences data bank, indicating that it may belong to a novel protein family involved in fertilization. AQN-1 shares extensive structural, as well as functional, similarity with two other boar sperm zona-pellucida-binding proteins, AQN-3 and AWN, which we have recently characterized. To name this protein family, we have coined the term spermadhesin. Our data may be relevant for identification of spermadhesins in other species, and thus may contribute to a better understanding of the species-specific sperm-egg recognition mechanism.

Amino Acid Sequence↗
PubMed1992

The complete primary structure of the spermadhesin AWN, a zona pellucida-binding protein isolated from boar spermatozoa.

AWN is a boar protein which originates in secretions of the male accessory glands and which becomes sperm surface-associated upon ejaculation. It is one of the components thought to mediate sperm adhesion to the egg's zona pellucida through a carbohydrate-recognition mechanism. AWN may, thus, participate in the initial events of fertilization in the pig. In this report we describe its complete primary structure by combination of protein-chemical and mass spectrometric methods. AWN exists as two isoforms, AWN-1 and AWN-2, which differ in that AWN-2 is N-terminally acetylated. The amino acid sequence of AWN contains 133 amino acid residues and two disulphide bridges between nearest-neighbour cysteine residues. Analysis of the amino acid sequence of the AWN proteins showed significant similarity only to AQN-1 and AQN-3, two other boar spermadhesins.

Amino Acid Sequence↗
PubMed1992

Boar spermadhesins AQN-1 and AWN are sperm-associated acrosin inhibitor acceptor proteins.

Trypsin-like inhibitors secreted by the male accessory sex glands have been identified in the seminal plasma of every mammalian species so far investigated. They bind to acceptor molecules on the anterior part of ejaculated sperm, and are thought to play a role in the capacitation of spermatozoa stabilizing zona pellucida binding sites during sperm uterine passage, and then dissociating to allow sperm-egg's zona pellucida interaction. Here we report the identification of acrosin inhibitor acceptor molecules isolated from boar seminal plasma. These proteins, termed AQN-1 and AWN, belong to the recently described spermadhesin protein family, whose members have been implicated in sperm-zona pellucida recognition events. Thus, members of the spermadhesin family, although not possessing detectable enzymatic activity, show features of serine proteinases, and may be involved in both sperm capacitation and sperm-egg recognition and binding events.

Acrosin↗
PubMed1992

Isolation and biochemical characterization of two isoforms of a boar sperm zona pellucida-binding protein.

Protein-carbohydrate complementarity has been recognized as a general mechanism of gamete recognition and adhesion in the process of fertilization throughout the whole animal kingdom. It appears that carbohydrate-binding molecules on the anterior sperm head surface mediate the binding of the male gamete to certain glycoconjugates present on the egg's extracellular coat. Subtle differences in protein and carbohydrate conformation may confer to this interaction a species-specific character. The mechanism responsible for gamete recognition is, however, poorly understood. A step in its elucidation is the characterization of the complementary molecules on the egg and sperm surfaces. With this aim we report here the isolation and partial structural characterization of two isoforms of a zona pellucida-binding protein (which we call AWN-1 and AWN-2) from boar spermatozoa, including partial sequence determination, assignment of disulphide bonds and identification of an N-terminal blocking group. AWN-1 and AWN-2 were isolated from acid extracts of washed ejaculated sperm and were present in seminal vesicle secretions, but absent in samples of epididymal fluid, suggesting a seminal vesicle origin for these sperm proteins. No analogous protein sequence could be found in the MIPS data bank, indicating that the AWN proteins may belong to a novel mammalian protein family involved in fertilization.

Amino Acid Sequence↗
PubMed1992

[Prostate transurethral resection syndrome].

The "transurethral resection of prostate" syndrome (TURPS) is the clinical manifestation of the resorption into the patient's body of a large amount of glycocolle-containing irrigating fluid used for this procedure. The full clinical picture, which is seldom seen, consists of dyspnoea, nausea, arterial hypertension, an increased central venous pressure, cerebral oedema, cardiogenic shock and renal failure. Improved surgical techniques, as well as incomplete and atypical forms of the syndrome could explain this low incidence. Absorption into the blood stream may be rapid, by way of the prostatic venous plexi, or slower, from the spaces around the prostate and under the peritoneum. The present-day pathophysiological theory explains this syndrome by an acute hyponatraemia, sometimes dissociated from the hypoosmolality, the toxicity of glycocolle, and the neurological effects of hyperammonemia. Acute hyponatraemia, with blood sodium concentrations below 115 to 120 mmol.l-1, should be considered as potentially serious. The different mechanisms involved may act alone or together, thus explaining that the minor forms of the syndrome mostly consist of a neurological picture. The emergency treatment depends on the natraemia. It includes diuretics and progressive reloading of the patient with sodium in case of severe hyponatraemia with seizures. The best prevention is a correct surgical indication and technique. The resection should not last for more than 90 to 120 min. The major problem remains the early diagnosis of TURPS. Carrying out this surgery under regional anaesthesia is helpful for this purpose, but, in the near future, the best means might be the monitoring of expired ethanol concentrations.

Glycine↗
PubMed1992

Phospholipase C-mediated hydrolysis of phosphatidylcholine is a target of transforming growth factor beta 1 inhibitory signals.

Cell growth and tumor transformation can be restrained in certain cell systems by the action of transforming growth factor beta (TGF-beta). It has been established that the mechanism whereby TGF-beta 1 inhibits cell growth does not interfere with the triggering of early mitogenic signal transduction mechanisms. Phospholipase C-catalyzed hydrolysis of phosphatidylcholine (PC) is a relatively late step in the cascade activated by growth factors. Therefore, conceivably activation of phospholipase C-catalyzed hydrolysis of PC could be the target of TGF-beta 1 action. In the study reported here, we demonstrate that TGF-beta 1 inhibits the coupling of ras p21 to the activation of PC hydrolysis, which appears to be critical for the antiproliferative effects of TGF-beta 1.

Animals↗
PubMed1992

Evidence for a role of protein kinase C zeta subspecies in maturation of Xenopus laevis oocytes.

A number of studies have demonstrated the activation of phospholipase C-mediated hydrolysis of phosphatidylcholine (PC-PLC) both by growth factors and by the product of the ras oncogene, p21ras. Evidence has been presented indicating that the stimulation of this phospholipid degradative pathway is sufficient to activate mitogenesis in fibroblasts as well as that it is sufficient and necessary for induction of maturation in Xenopus laevis oocytes. However, the mechanism whereby PC-PLC transduces mitogenic signals triggered by growth factors or oncogenes remains to be elucidated. In this study, data are presented that show the involvement of protein kinase C zeta subspecies in the channelling of the mitogenic signal activated by insulin-p21ras-PC-PLC in Xenopus oocytes as well as the lack of a critical role of protein kinase C isotypes alpha, beta, gamma, delta, and epsilon in these pathways.

Amino Acid Sequence↗
PubMed1991

Protein kinase C-independent expression of stromelysin by platelet-derived growth factor, ras oncogene, and phosphatidylcholine-hydrolyzing phospholipase C.

Changes in the expression of several genes play critical roles in cell growth and tumor transformation. A number of proteases are increased in some tumors, and the level of these enzymes correlates with the metastatic potential of several cancer cell lines. Stromelysin, with the widest substrate specificity, can degrade the extracellular matrix conferring metastatic potential to tumor cells. The mechanisms whereby growth factors and oncogenes control the expression of stromelysin are beginning to be characterized. In the study shown here we also identify a region in the stromelysin promoter which is involved in the induction of stromelysin in response to platelet-derived growth factor, phosphatidylcholine-hydrolyzing phospholipase C, and ras oncogene. Our results are consistent with the notion that platelet-derived growth factor/phosphatidylcholine-hydrolyzing phospholipase C induces stromelysin gene expression through a phorbol myristate acetate/protein kinase C-independent mechanism by acting through elements in the stromelysin promoter distinct from the 12-O-tetradecanoylphorbol-13-acetate-responsive element.

Base Sequence↗
PubMed1991

The amino acid sequence of AQN-3, a carbohydrate-binding protein isolated from boar sperm. Location of disulphide bridges.

Gamete recognition and adhesion are essential steps in fertilization. Among others, carbohydrate-binding proteins on the sperm surface have been recognized to play a central role in the initial interaction of the male gamete with components of the zona pellucida of the homologous investing oocyte. We have isolated several members of a carbohydrate- and zona pellucida-binding protein family from ejaculated sperm. Here we report the biological origin and structural characterization of AQN-3, a component of this carbohydrate-binding family. The molecular weight of purified AQN-3 was determined by plasma desorption mass spectrometry. The protein was chemically and enzymatically degraded, the proteolytic fragments isolated and characterized by N-terminal sequencing and fast atom bombardment mass spectrometry. In this manner we established the complete amino acid sequence of AQN-3 and the location of its two disulphide bonds. No analogous protein sequence could be found in the MIPS protein sequence data bank, indicating that AQN-3 may belong to a novel mammalian carbohydrate-binding protein family.

Amino Acid Sequence↗
PubMed1991

Isolation and biochemical characterization of a zona pellucida-binding glycoprotein of boar spermatozoa.

Lectin-like molecules on the sperm surface are implicated in the process of gamete recognition and adhesion. We have isolated and biochemically characterized a 15 kDa glycoprotein from ejaculated boar sperm which possess zona pellucida-binding- and haemagglutinating-activity. The zona/15 kDa protein interaction is inhibited by fucoidan, suggesting that the glycoprotein is one of the sperm components which participate in the initial gamete interaction. N-Terminal sequence analysis of the isolated 15 kDa glycoprotein showed that it may belong to the same sperm/egg recognition-mediating protein family as the sea urchin sperm protein binding.

Amino Acid Sequence↗
PubMed1991

[Coma during transurethral resection of the prostate].

Two cases of coma occurring during transurethral resection of the prostate are reported. The 76 and 85-year-old patients lapsed into coma, ranking 9 and 8 on the Glasgow scale, respectively 90 and 120 min after the start of the resection, without any previous haemodynamic alterations. In one patient, coma occurred when the urethral catheter became blocked with fragments of prostates. In the other, coma was initiated by a rupture of the prostatic capsule, with passage of washing fluid (1.5% glycine solution) into the peritoneal cavity. The role played by acute hyponatraemia (128 and 123 mmol.l-1 respectively) and glycine poisoning (10,188 and 11,840 mmol.l-1 respectively) are discussed. These cases underline the interest of regional anaesthetic techniques, allowing an early diagnosis and a rapid surgical procedure which will avoid a worsening of the condition.

Administration, Intravesical↗
PubMed1990

[Indications for subcapsular nephrectomy in children].

Subcapsular nephrectomy has advantages over classical nephrectomy in such cases with the kidney adhered to adjacent structures. Actually, to the usual indications, as chronic renal infection and previous renal surgery, we add up the nephrectomy of transplanted kidney, that forms our main indications. In our review of medical literature we haven't found any references about subcapsular nephrectomy in pediatric age. We report 31 cases of subcapsular nephrectomy from a total number of 121 nephrectomies performed in children during the last 20 years. We analyse the indications, surgical management, postoperative course and latter complications of subcapsular nephrectomy.

Adolescent↗
PubMedDate not supplied

Immunohistochemical localization in the stallion genital tract, and topography on spermatozoa of seminal plasma protein SSP-7, a member of the spermadhesin protein family.

SSP-7 is a protein originally isolated from stallion seminal plasma. It has extensive amino acid sequence homology with boar spermadhesin AWN, and, like its porcine counterpart, SSP-7 displays zona pellucida-binding activity. Strikingly, however, immunohistochemical studies presented here show that the stallion and the boar spermadhesin homologues are secreted at different places of the male genital tract. Furthermore, indirect immunofluorescence shows that the topography of SSP-7 on the surface of stallion spermatozoa is restricted to the equatorial segment, whereas boar AWN epitopes cover the entire acrosomal cap membrane. The different cellular origin and compartimentalization of spermadhesin molecules in different species suggest that structurally related proteins could be involved in species-specific aspects of mammalian fertilization.

Acrosome↗
PubMedDate not supplied

Spermadhesins: a new protein family. Facts, hypotheses and perspectives.

Spermadhesins are a novel family of secretory proteins expressed in the male genital tract of pig, horse and bull. They are major products of the seminal plasma and have been found to be peripherally associated to the sperm surface. The structure and function of spermadhesins have been thoroughly investigated in the pig, which exhibits the greatest diversity of members: AWN, AQN-1, AQN-2, PSP-I and PSP-II and its glycosylated isoforms. They are multifunctional proteins showing a range of ligand-binding abilities, e.g. carbohydrates, sulfated glycosaminoglycans, phospholipids and protease inhibitors, suggesting that they may be involved in different steps of fertilization. Isolated porcine spermadhesins bind the zona pellucida glycoproteins in a cation-dependent manner with a Kd in a low micromolar range, and AWN, AQN-1 and AQN-3 display similar binding affinity for glycoproteins containing Gal beta(1-3)-GalNAc and Gal beta(1-4)-GlcNAc sequences in O-linked and N-linked oligosaccharides, respectively. During sperm passage through the epididymis AQN-3 and AWN have been shown to bind tightly to the sperm surface by interaction with the phospholipids of the membrane bilayer. At ejaculation the spermadhesins form a protective coat around the sensitive acrosomal region of the sperm head, thus possibly preventing premature acrosome reaction. During in vitro capacitation most of these aggregated sperm adhesins are lost, with the exception of phospholipid-bound spermadhesins. AWN and AQN-3 may now serve as a primary receptor for the oocyte zona pellucida, thus contributing to initial binding and recognition between sperm and egg. The amino acid sequence of spermadhesins does not show any discernible similarity with known carbohydrate recognition domains (CRD). However, they belong to the superfamily of proteins with a CUB domain with a predicted all-beta structure. The crystal structure of the heterodimeric complex of the spermadhesins PSP-I/PSP-II has been solved, showing that the overall structure of both spermadhesins consists of a beta-sandwich with five (parallel and antiparallel) beta-strands. It is the first three-dimensional structure of a zona pellucida-binding protein and reveals the architecture of the CUB domain. The spermadhesins represent a novel class of lectins that may be involved in sequential steps of fertilization, at least in the pig.

Animals↗