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M Baca

Publications and source records attributed to M Baca.

At least 19 recordsLinked to original sources
PubMed2005

Relaxin and prostaglandin E(2) regulate interleukin 11 during human endometrial stromal cell decidualization.

Decidualization of endometrial stromal cells and IL-11 signaling are essential for embryo implantation in the mouse. We investigated the effects of relaxin (RLX) and prostaglandin E(2) (PGE(2)) on IL-11 secretion by human endometrial stromal cells (HESC) and during cAMP or medroxyprogesterone acetate (P)-induced decidualization. cAMP-decidualized HESC secreted high levels of IL-11. RLX, cAMP, or PGE(2) increased IL-11 mRNA and IL-11 secretion, with maximal response to RLX and cAMP. Addition of the cAMP/protein kinase A inhibitor Rp-adenosine-3,5-cyclic-monophosphorothioate to either RLX- or PGE(2)-treated cells decreased IL-11 secretion. Indomethacin treatment decreased IL-11 secretion, which was largely restored by cotreatment with PGE(2) or RLX. Cotreatment of HESC with RLX, PGE(2), or cAMP and estrogen plus P down-regulated IL-11 mRNA and IL-11 secretion at 24 h, before secretion of prolactin (decidualization marker). Addition of W147AIL-11 (IL-11 signaling inhibitor) reduced prolactin secretion stimulated by RLX or PGE(2) and estrogen plus P. This is the first demonstration that cAMP-decidualized HESC secrete IL-11 and that IL-11 mRNA and IL-11 secretion are regulated by RLX and PGE(2), partly via a cAMP/protein kinase A-dependent pathway. Blocking IL-11 signaling reduced RLX+P- or PGE(2)+P-induced decidualization, suggesting that RLX and PGE(2) act via IL-11. This is important in understanding implantation and regulation of fertility.

Animals↗
PubMed2002

[Long-term results of retropubic vesicopexy in the treatment of urinary stress incontinence in women].

OBJECTIVE: To evaluate long-term results of retropubic vesicopexy (e.g. direct suspension of the anterior and lateral walls of the bladder base) in the treatment of female stress urinary incontinence (SUI) caused by hypermobile urethra. DESIGN: Retrospective clinical study. SETTING: Department of Urology, Faculty of Medicine, University of P. J. Safarik, Kosice, Slovakia. METHODS: From a total of 44 females operated on between 1985-1992, 41 (93%) were available for the study (mean age 50 years, 28 pure SUI, 13 mixed incontinence). 18 (44%) patients had failed previous incontinence surgery. Based on the data collected by a detailed questionnaire as a success cure and/or significant improvement (max. 1 pad/day) of SUI have been considered. RESULTS: With a mean of 103 month follow-up period (48-160 months), 32 (78%) patients reported to have their SUI cured, another 5 (12%) significantly improved. Both persistent (8/13, 62%) and de novo urge incontinence (5/28, 18%) have shown to the main reasons for "partial" satisfaction only with the outcome of surgery. Perioperative bleeding requiring blood transfusion was the only serious complication met with this procedure (2 patients). CONCLUSION: Long-term results of vesicopexy is comparable with the effect of standard retropubic procedures like Burch colposuspension or MMK urethropexy. Technical simplicity, no risk of osteitis pubis as well as persisting micturition problems may be considered the main advantages of the procedure. Because of lower cure rate the procedure is less suitable for SUI type IIB.

Adult↗
PubMed2001

Structure-function analysis of a phage display-derived peptide that binds to insulin-like growth factor binding protein 1.

Highly structured, peptide antagonists of the interaction between insulin-like growth factor 1 (IGF-I) and IGF binding protein 1 (IGFBP-1) have recently been discovered by phage display of naïve peptide libraries [Lowman, H. B., et al. (1998) Biochemistry 37, 8870--8878]. We now report a detailed analysis of the features of this turn-helix peptide motif that are necessary for IGFBP-1 binding and structural integrity. Further rounds of phage randomization indicate the importance of residues contributing to a hydrophobic patch on one face of the helix. Alanine-scanning substitutions confirm that the hydrophobic residues are necessary for binding. However, structural analysis by NMR spectroscopy indicates that some of these analogues are less well folded. Structured, high-affinity analogues that lack the disulfide bond were prepared by introducing a covalent constraint between side chains at positions i and i + 7 or i + 8 within the helix. Analogues based on this scaffold demonstrate that a helical conformation is present in the bound state, and that hydrophobic side chains in this helix, and residues immediately preceding it, interact with IGFBP-1. By comparison of alanine scanning data for IGF-I and the turn-helix peptide, we propose a model for common surface features of these molecules that recognize IGFBP-1.

Alanine↗
PubMed2001

Direct inhibition of caspase 3 is dispensable for the anti-apoptotic activity of XIAP.

XIAP is a mammalian inhibitor of apoptosis protein (IAP). To determine residues within the second baculoviral IAP repeat (BIR2) required for inhibition of caspase 3, we screened a library of BIR2 mutants for loss of the ability to inhibit caspase 3 toxicity in the yeast Schizosaccharomyces pombe. Four of the mutations, not predicted to affect the structure of the BIR fold, clustered together on the N-terminal region that flanks BIR2, suggesting that this is a site of interaction with caspase 3. Introduction of these mutations into full-length XIAP reduced caspase 3 inhibitory activity up to 500-fold, but did not affect its ability to inhibit caspase 9 or interact with the IAP antagonist DIABLO. Furthermore, these mutants retained full ability to inhibit apoptosis in transfected cells, demonstrating that although XIAP is able to inhibit caspase 3, this activity is dispensable for inhibition of apoptosis by XIAP in vivo.

Amino Acid Sequence↗
PubMed2000

Cloning and characterization of the genes encoding the ankyrin repeat and SOCS box-containing proteins Asb-1, Asb-2, Asb-3 and Asb-4.

Members of the suppressor of cytokine signalling (SOCS) family of proteins have been shown to inhibit cytokine signalling via direct interactions with JAK kinases or activated cytokine receptors. In addition to their novel amino-terminal regions and SH2 domains that mediate these interactions, the SOCS proteins also contain carboxy-terminal regions of homology called the SOCS box. The SOCS box serves to couple SOCS proteins and their binding partners with the elongin B and C complex, possibly targeting them for degradation. Several other families of proteins also contain SOCS boxes but differ from the SOCS proteins in the type of domain or motif they contain upstream of the SOCS box. We report here the cloning, characterization, mapping and expression analysis of four members of the ankyrin repeat and SOCS box-containing (Asb) protein family.

Amino Acid Sequence↗
PubMed2000

Chopper, a new death domain of the p75 neurotrophin receptor that mediates rapid neuronal cell death.

The cytoplasmic juxtamembrane region of the p75 neurotrophin receptor (p75(NTR)) has been found to be necessary and sufficient to initiate neural cell death. The region was named "Chopper" to distinguish it from CD95-like death domains. A 29-amino acid peptide corresponding to the Chopper region induced caspase- and calpain-mediated death in a variety of neural and non-neural cell types and was not inhibited by signaling through Trk (unlike killing by full-length p75(NTR)). Chopper triggered cell death only when bound to the plasma membrane by a lipid anchor, whereas non-anchored Chopper acted in a dominant-negative manner, blocking p75(NTR)-mediated death both in vitro and in vivo. Removal of the ectodomain of p75(NTR) increased the potency of Chopper activity, suggesting that it regulates the association of Chopper with downstream signaling proteins.

Antigens, CD↗
PubMed2000

Suppressor of cytokine signaling-3 preferentially binds to the SHP-2-binding site on the shared cytokine receptor subunit gp130.

Suppressor of cytokine signaling-3 (SOCS-3) is one member of a family of intracellular inhibitors of signaling pathways initiated by cytokines that use, among others, the common receptor subunit gp130. The SH2 domain of SOCS-3 has been shown to be essential for this inhibitory activity, and we have used a quantitative binding analysis of SOCS-3 to synthetic phosphopeptides to map the potential sites of interaction of SOCS-3 with different components of the gp130 signaling pathway. The only high-affinity ligand found corresponded to the region of gp130 centered around phosphotyrosine-757 (pY757), previously shown to be a docking site for the tyrosine phosphatase SHP-2. By contrast, phosphopeptides corresponding to other regions within gp130, Janus kinase, or signal transducer and activator of transcription proteins bound to SOCS-3 with weak or undetectable affinity. The significance of pY757 in gp130 as a biologically relevant SOCS-3 docking site was investigated by using transfected 293T fibroblasts. Although SOCS-3 inhibited signaling in cells transfected with a chimeric receptor containing the wild-type gp130 intracellular domain, inhibition was considerably impaired for a receptor carrying a Y-->F point mutation at residue 757. Taken together, these data suggest that the mechanism by which SOCS-3 inhibits the gp130 signaling pathway depends on recruitment to the phosphorylated gp130 receptor, and that some of the negative regulatory roles previously attributed to the phosphatase SHP-2 might in fact be caused by the action of SOCS-3.

Amino Acid Sequence↗
PubMed1999

The conserved SOCS box motif in suppressors of cytokine signaling binds to elongins B and C and may couple bound proteins to proteasomal degradation.

The suppressors of cytokine signaling (SOCS) family of proteins act as intracellular inhibitors of several cytokine signal transduction pathways. Their expression is induced by cytokine activation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway and they act as a negative feedback loop by subsequently inhibiting the JAK/STAT pathway either by direct interaction with activated JAKs or with the receptors. These interactions are mediated at least in part by the SH2 domain of SOCS proteins but these proteins also contain a highly conserved C-terminal homology domain termed the SOCS box. Here we show that the SOCS box mediates interactions with elongins B and C, which in turn may couple SOCS proteins and their substrates to the proteasomal protein degradation pathway. Analogous to the family of F-box-containing proteins, it appears that the SOCS proteins may act as adaptor molecules that target activated cell signaling proteins to the protein degradation pathway.

Amino Acid Sequence↗
PubMed1999

Mutational analyses of the SOCS proteins suggest a dual domain requirement but distinct mechanisms for inhibition of LIF and IL-6 signal transduction.

SOCS-1 (suppressor of cytokine signaling-1) is a representative of a family of negative regulators of cytokine signaling (SOCS-1 to SOCS-7 and CIS) characterized by a highly conserved C-terminal SOCS box preceded by an SH2 domain. This study comprehensively examined the ability of several SOCS family members to negatively regulate the gp130 signaling pathway. SOCS-1 and SOCS-3 inhibited both interleukin-6 (IL-6)- and leukemia inhibitory factor (LIF)-induced macrophage differentiation of murine monocytic leukemic M1 cells and LIF induction of a Stat3-responsive reporter construct in 293T fibroblasts. Deletion of amino acids 51-78 in the N-terminal region of SOCS-1 prevented inhibition of LIF signaling. The SOCS-1 and SOCS-3 N-terminal regions were functionally interchangeable, but this did not extend to other SOCS family members. Mutation of SH2 domains abrogated the ability of both SOCS-1 and SOCS-3 to inhibit LIF signal transduction. Unlike SOCS-1, SOCS-3 was unable to inhibit JAK kinase activity in vitro, suggesting that SOCS-1 and SOCS-3 act on the JAK-STAT pathway in different ways. Thus, although inhibition of signaling by SOCS-1 and SOCS-3 requires both the SH2 and N-terminal domains, their mechanisms of action appear to be biochemically different.

Animals↗
PubMed1999

Suppressors of cytokine signaling (SOCS): negative regulators of signal transduction.

SOCS-1 was originally identified as an inhibitor of interleukin-6 signal transduction and is a member of a family of proteins (SOCS-1 to SOCS-7 and CIS) that contain an SH2 domain and a conserved carboxyl-terminal SOCS box motif. Mutation studies have established that critical contributions from both the amino-terminal and SH2 domains are essential for SOCS-1 and SOCS-3 to inhibit cytokine signaling. Inhibition of cytokine-dependent activation of STAT3 occurred in cells expressing either SOCS-1 or SOCS-3, but unlike SOCS-1, SOCS-3 did not directly interact with or inhibit the activity of JAK kinases. Although the conserved SOCS box motif appeared to be dispensable for SOCS-1 and SOCS-3 action when overexpressed, this domain interacts with elongin proteins and may be important in regulating protein turnover. In gene knockout studies, SOCS-1(-/-) mice were born but failed to thrive and died within 3 weeks of age with fatty degeneration of the liver and hemopoietic infiltration of several organs. The thymus in SOCS-1(-/-) mice was small, the animals were lymphopenic, and deficiencies in B lymphocytes were evident within hemopoietic organs. We propose that the absence of SOCS-1 in these mice prevents lymphocytes and liver cells from appropriately controlling signals from cytokines with cytotoxic side effects.

Animals↗
PubMed1999

Night splint treatment for plantar fasciitis. A prospective randomized study.

A prospective randomized study of 116 patients with plantar fasciitis was performed to determine the effectiveness of adjuvant night splint therapy in relieving the acute symptoms of plantar fasciitis. Patients were randomized into one of two groups. Patients in Group 1 were treated with 1 month of oral antiinflammatory medication, Achilles stretching exercises, and shoe recommendations. Patients in Group 2 received identical treatment but also used a dorsiflexion night splint for 3 months. Blinded clinical review of patients was performed at 4, 6, and 12 weeks. Health status data Short Form 36 also was collected at these times and again at an average 19 months of followup. Overall, 68% of patients reported improvement with this nonoperative protocol for a 12-week period. No statistical difference was seen with the presence or absence of a night splint. In addition, no differences in improvement rates were observed with gender, duration of antecedent symptoms, the presence of bilateral symptoms, or the presence of a heel spur. Age older than 45 years did prove to be a statistically significant poor prognostic factor for improvement at the 12-week follow-up. Short Form 36 data obtained at baseline showed significantly lowered perception of health when compared with age matched controls. Patients in both treatment groups had significant improvement in Short Form 36 scores with 12 weeks of conservative care.

Fasciitis↗
PubMed1997

Phage display of a catalytic antibody to optimize affinity for transition-state analog binding.

Catalytic antibodies have shown great promise for catalyzing a tremendously diverse set of natural and unnatural chemical transformations. However, few catalytic antibodies have efficiencies that approach those of natural enzymes. In principle, random mutagenesis procedures such as phage display could be used to improve the catalytic activities of existing antibodies; however, these studies have been hampered by difficulties in the recombinant expression of antibodies. Here, we have grafted the antigen binding loops from a murine-derived catalytic antibody, 17E8, onto a human antibody framework in an effort to overcome difficulties associated with recombinant expression and phage display of this antibody. "Humanized" 17E8 retained similar catalytic and hapten binding properties as the murine antibody while levels of functional Fab displayed on phage were 200-fold higher than for a murine variable region/human constant region chimeric Fab. This construct was used to prepare combinatorial libraries. Affinity panning of these resulted in the selection of variants with 2- to 8-fold improvements in binding affinity for a phosphonate transition-state analog. Surprisingly, none of the affinity-matured variants was more catalytically active than the parent antibody and some were significantly less active. By contrast, a weaker binding variant was identified with 2-fold greater catalytic activity and incorporation of a single substitution (Tyr-100aH --> Asn) from this variant into the parent antibody led to a 5-fold increase in catalytic efficiency. Thus, phage display methods can be readily used to optimize binding of catalytic antibodies to transition-state analogs, and when used in conjunction with limited screening for catalysis can identify variants with higher catalytic efficiencies.

Animals↗
PubMed1997

Antibody humanization using monovalent phage display.

Antibody humanization often requires the replacement of key residues in the framework regions with corresponding residues from the parent non-human antibody. These changes are in addition to grafting of the antigen-binding loops. Although guided by molecular modeling, assessment of which framework changes are beneficial to antigen binding usually requires the analysis of many different antibody mutants. Here we describe a phage display method for optimizing the framework of humanized antibodies by random mutagenesis of important framework residues. We have applied this method to humanization of the anti-vascular endothelial growth factor murine monoclonal antibody A4.6.1. Affinity panning of a library of humanized A4.6.1 antibody mutants led to the selection of one variant with greater than 125-fold enhanced affinity for antigen relative to the initial humanized antibody with no framework changes. A single additional mutation gave a further 6-fold improvement in binding. The affinity of this variant, 9.3 nM, was only 6-fold weaker than that of a murine/human chimera of A4.6.1. This method provides a general means of rapidly selecting framework mutations that improve the binding of humanized antibodies to their cognate antigens and may prove an attractive alternative to current methods of framework optimization based on cycles of site-directed mutagenesis.

Amino Acid Sequence↗
PubMed1997

Actinomycosis of the urachus persistens penetrating into the ileum.

A 16-year-old boy is presented with the problem of free micturition, having a palpable, painless tumour spreading from the symphysis to the umbilicus. Cystoscopy revealed an impression in the vertex of the urinary bladder covered by the inflamed mucous membrane with a bulbar oedema. Fistulography showed transitional urachus persistens communicating with the terminal loops of the ileum. During surgery, a solid, fan-like fibrous connective tissue was removed, together with the vertex of the urinary bladder and peritoneum. Adhering loops of the terminal ileum were sharply separated and sutured. Histopathological examination confirmed actinomycosis of the urachus persistens penetrating into the ileum.

Actinomycosis↗
PubMed1995

Immunization of pigs against Taenia solium cysticercosis: factors related to effective protection.

Fifty-six (56) pigs were immunized against Taenia solium cysticercosis with antigens from Taenia crassiceps metacestodes, in a variety of protocols, and then challenged orally with Taenia solium proglottids or eggs. Results of immunization (expressed as individual parasite loads) ranged from significant reduction of parasite loads (host protection) to clear increase (parasite facilitation) in apparent relation to the immunogen dose, adjuvant employed and genetic background of the pigs. In all trials, however, immunized pigs harboured more damaged cysticerci than controls, indicating that immunization does induce some restrictions to parasite these are eventually overwhelmed by other parasite-promoting factors. Western blots in immunized-protected pigs indicated antigens of 242, 234, 118, 77, 55 and 45 kDa as possibly being involved in immunological protection.

Animals↗
PubMed1995

Is alpha-tocopherol a reservoir for alpha-tocopheryl hydroquinone?

The products of oxidation of the alpha-tocopherol model compound, 2,2,5,7,8-pentamethyl-6-chromanol (PH) by t-butyl hydroperoxide in chloroform varied with the amount of water present. In the presence of a trace of water, the main products were the spirodimer (PSD) and spirotrimer (PST). As the content of water increased, the main product became 2-(3-hydroxy-3-methylbutyl)-3,5,6-trimethyl-1,4-benzoquinone (PQ). Oxidation of PH in aqueous liposome suspension also produced PQ as the major product. These results suggested that, in aqueous solutions, the major oxidation product of PH would be PQ and of alpha-tocopherol (TH) would be alpha-tocopheryl quinone (TQ). The ease of reduction of PQ and TQ was studied in chemical and biological systems. PQ, TQ, and ubiquinone-10 (UQ) were rapidly reduced to their respective hydroquinones (PQH2, TQH2, and UQH2) at pH 7.3 by NADH plus FAD. Whole blood reduced PQ rapidly at 37 degrees C to PQH2 but did not reduce TQ to TQH2. Human peripheral blood mononuclear cells took up TQ from a bovine serum albumin complex and reduced it to TQH2. Ingestion of TQ (350 mg) by one of us (PSK) resulted in the formation of TQH2 during a 5 h period. These results demonstrate that several biological systems are able to reduce TQ to TQH2 and that it is a reaction that may occur normally in vivo.

Blood↗