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PubMed2005

Brief report: A longitudinal investigation of the relation between a negative cognitive triad and depressive symptoms in youth.

The present study examined self-reported depressive symptoms and associated cognitive features by reporting data from a 1-year longitudinal study of a community sample of 93 children and 69 adolescents. Results revealed that in childhood a negative cognitive triad appeared to be more a consequence than a predictor of depressive symptoms after 1 year. In adolescence, a negative view of the future was predictive of depressive symptoms after 1 year. A negative cognitive triad also appeared to be a consequence of depressive symptoms. The results imply that in youth depressive symptoms produce changes in the cognitive style, which may put them at risk for future episodes of depression.

Adolescent↗
PubMed2004

A novel connexin 26 gene mutation associated with features of the keratitis-ichthyosis-deafness syndrome and the follicular occlusion triad.

We report the case of a congenitally deaf white male with mild palmoplantar keratoderma, ichthyosiform scaling, follicular hyperkeratosis, and mild keratitis, features consistent with keratitis-ichthyosis-deafness syndrome. His major problem was severe, disfiguring, inflammatory dissecting folliculitis of the scalp, hidradenitis suppurativa, and cystic acne, features comprising the follicular occlusion triad. This unusual phenotype is associated with a novel heterozygous point mutation (C119T) in the gap junction beta2 gene that substitutes a valine for alanine at codon 40 (A40V) in the connexin 26 protein. Through Xenopus oocyte expression studies, this mutant protein was shown to significantly disrupt the function of the specialized gap junctions connecting the cytoplasm of adjacent cells critical for tissue homeostasis. Mutations within the connexin 26 protein are associated with syndromes involving both sensorineural deafness and hyperkeratotic skin disorders. This is the first report of an association between a connexin 26 protein mutation, follicular hyperkeratosis of keratitis-ichthyosis-deafness syndrome, and severe follicular occlusion triad.

Acne Vulgaris↗
PubMed2005

Cloning, expression, and catalytic triad of recombinant arylformamidase.

Arylformamidase (AFMID) is the second enzyme of the kynurenine pathway metabolizing tryptophan to nicotinic acid and nicotinamide adenine dinucleotide cofactors. Inhibition of AFMID by organophosphorus insecticides in developing chicken embryos is correlated with lowered NAD levels and severe teratogenesis. The cDNA sequence previously identified for mouse liver AFMID (AF399717) (MW 34229) was cloned and expressed in Escherichia coli. Residues identified as potential catalytic triad members (S162, D247, and H279) through sequence motif and homology modeling were mutated to alanine to probe their contributions to enzyme activity. The wild-type and mutant AFMIDs were expressed as amino terminal 6 x His-tagged recombinant proteins to facilitate purification. Three chromatography steps isolated highly purified proteins for enzyme activity comparisons. Expressed AFMID showed high activity, 42+/-1 micromol/min/mg protein, for its natural substrate, N-formyl-l-kynurenine. The same K(m) (0.18--0.19 mM) was observed for expressed and native cytosolic AFMID. The single mutants (S162A, D247A, and H279A) lost essentially all (>99%) activity. The predicted catalytic triad of S162, D247, and H279 is therefore confirmed by site-directed mutagenesis.

Amino Acid Substitution↗
PubMed2005

Active spleno-femoral shunt avoids splanchnic congestion during portal triad occlusion: an experimental study.

UNLABELLED: Portal triad occlusion (PTO) is often performed during hepatic resections for trauma or malignancies to minimize intraoperative blood loss. The pringle maneuver is also regularly required during liver transplantation. This maneuver leads to temporary hepatic ischemia and may be associated with splanchnic blood flow congestion, promoting undesirable hemodynamic disturbances in some patients. Veno-venous bypass is a useful, easily performed technique that may avoid those deleterious hemodynamic effects of PTO. We tested the hypothesis that an active spleno-femoral shunt maintains hemodynamic stability and promotes complete decompression of the mesenteric bed, avoiding intestinal mucosal blood congestion, during PTO. METHODS: Seven dogs (17.2 +/- 0.9 kg) were subjected to 45 minutes of hepatic ischemia during which there was an active spleno-femoral shunt. Systemic hemodynamics were evaluated through Swan-Ganz and arterial catheters. Splanchnic perfusion was assessed by portal vein blood flow and hepatic artery blood flow (PVBF and HABF, ultrasonic flowprobe), intestinal mucosal-arterial pCO(2) gradient (D(t-a)pCO(2), tonometry), and regional O(2)-derived variables. RESULTS: No significant changes in systemic and regional parameters were observed during the ischemia period. During reperfusion, a significant decrease in mean arterial pressure, PVBF, and arterial pH was observed. A significant increase in ALT and D(t-a)pCO(2) (4.8 +/- 2.5 to 18.9 +/- 3 mm Hg) was also observed following hepatic blood flow restoration. CONCLUSION: Spleno-femoral shunt maintains systemic hemodynamic stability, with an effective decompression of the splanchnic bed during portal triad occlusion. The deleterious hemodynamic and metabolic effects observed during reperfusion period, such as transitory hypotension, high D(t-a)pCO(2), and acidemia, were associated with an isolated hepatic ischemia-reperfusion injury, not with the blood congestion in the splanchnic bed.

Animals↗
PubMed1985

Effects of mercaptans upon dihydropyridine binding sites on transverse tubules isolated from triads of rabbit skeletal muscle.

The binding of nitrendipine to transverse (T) tubules isolated from skeletal muscle triads is inhibited by dithiothreitol (KI approximately 0.05 mM) and glutathione (KI approximately 3 mM). The t 1/2's of inhibition (18.3 and 11.5 min, respectively) suggest that these hydrophylic reagents act upon the exposed surface of the vesicles. Dithiothreitol shifts the apparent KD for nitrendipine from 8.5 nM to 30 nM without altering the Bmax extrapolated by Scatchard analysis. That T-tubules isolated by disruption of triad junctions are constrained to have the protoplasmic (P) face uniformly exposed was experimentally confirmed. These studies show that a sulfhydryl residue on the P-face of the T-tubule influences the affinity of the receptor for dihydropyridines.

Animals↗
PubMed1991

Nonmammalian vertebrate skeletal muscles express two triad junctional foot protein isoforms.

Mammalian skeletal muscles express a single triad junctional foot protein, whereas avian muscles have two isoforms of this protein. We investigated whether either case is representative of muscles from other vertebrate classes. We identified two foot proteins in bullfrog and toadfish muscles on the basis of (a) copurification with [3H]epiryanodine binding; (b) similarity to avian muscle foot proteins in native and subunit molecular weights; (c) recognition by anti-foot protein antibodies. The bullfrog and toadfish proteins exist as homooligomers. The subunits of the bullfrog muscle foot protein isoforms are shown to be unique by peptide mapping. In addition, immunocytochemical localization established that the bullfrog muscle isoforms coexist in the same muscle cells. The isoforms in either bullfrog and chicken muscles have comparable [3H]epiryanodine binding capacities, whereas in toadfish muscle the isoforms differ in their levels of ligand binding. Additionally, chicken thigh and breast muscles differ in the relative amounts of the two isoforms they contain, the amounts being similar in breast muscle and markedly different in thigh muscle. In conclusion, in contrast to mammalian skeletal muscle, two foot protein isoforms are present in amphibian, avian, and piscine skeletal muscles. This may represent a general difference in the architecture and/or a functional specialization of the triad junction in mammalian and nonmammalian vertebrate muscles.

Animals↗
PubMed1998

Glycosphingolipids of skeletal muscle: II. Modulation of Ca2(+)-flux in triad membranes by gangliosides.

Membrane vesicles of rabbit skeletal muscle were prepared and separated by sucrose density gradient centrifugation. The fractions obtained (in the order of increasing density) were sarcolemma (SL), T-tubules (TT), sarcoplasmic reticulum (SR1 and SR2) and triads/mitochondria (Tr/M) as characterized by their specific marker enzymes, ligand binding, and ion flux activities. The distribution of neutral glycosphingolipids and gangliosides in these membrane preparations has been documented in the preceding paper (J. Müthing, U. Maurer, U. Neumann, B. Kniep, and S. Weber-Schürholz, Carbohydr, Res., (1988) 135-145). GM3(Neu5Ac) is the dominant ganglioside, neolacto-series gangliosides are moderately expressed and ganglio-series gangliosides were found in minor quantities, however, all showing different qualitative and quantitative membrane-type specific patterns. The voltage dependent Ca(2+)-channels of skeletal muscle reside prevalently in the triad enriched membrane fractions deduced from highest binding capacity of 1,4-dihydropyridines. Calcium channel complexes of triads were reconstituted into unilamellar phospholipid vesicles of 400 nm defined size and the active 45Ca(2+)-uptake into intravesicular space was measured after incorporation of muscle specific gangliosides into the outer vesicle lipid bilayer in parallel to control liposomes without gangliosides. GM3(Neu5Ac) strongly increased the uptake of 45Ca2+ (+285%) whereas GM3(Neu5Gc) severely inhibited the ion flux (-61%). Neolacto-series gangliosides evoked miscellaneous effects upon 45Ca(2+)-flux depending on isomeric sialic acid configuration, oligosaccharide size and fatty acid chain length of the ceramide portion. VI3Neu5Ac-nLcOse6Cer (C24-fatty acid), IV3Neu5Ac-nLcOse4Cer (C16-fatty acid) and IV6Neu5Ac-nLcOse4Cer (C16-fatty acid) strongly enhanced the 45Ca(2+)-flux (+208, +162, and +120%, respectively, whereas IV3Neu5Ac-nLcOse4Cer (C24-fatty acid), VI3Neu5Ac-nLcOse6Cer (C16-fatty acid) and IV6Neu5Ac-nLcOse4Cer (C24-fatty acid) slightly reduced 45Ca(2+)-flux (-3, -6, and -17%, respectively). Out of all gangliosides tested in this study, GM1 showed the strongest stimulatory effect (+327%). GD1a and GT1b gave rise to remarkable flux-stimulation of +283 and +255%, respectively, whereas GD1b exhibited only a slightly positive effect (+38%). This data suggest a functional role of gangliosides in subcellular muscle membranes giving strong evidence that gangliosides are capable of modulating the cytosolic calcium level of muscle, which regulates muscle contraction.

Animals↗
PubMed2000

Insertion of the full-length calcium channel alpha(1S) subunit into triads of skeletal muscle in vitro.

A full-length and a C-terminally truncated form of the calcium channel alpha(1S) subunit can be isolated from skeletal muscle. Here we studied whether full-length alpha(1S) is functionally incorporated into the skeletal muscle excitation-contraction coupling apparatus. A fusion protein of alpha(1S) with the green fluorescent protein attached to its C-terminus (alpha(1S)-GFP) or alpha(1S) and GFP separately (alpha(1S)+GFP) were expressed in dysgenic myotubes, which lack endogenous alpha(1S). Full-length alpha(1S)-GFP was targeted into triad junctions and restored calcium currents and excitation-contraction coupling. GFP remained colocalized with alpha(1S), indicating that intact alpha(1S)-GFP was inserted into triads and that the C-terminus remained associated with the excitation-contraction coupling apparatus.

Calcium Channels, L-Type↗
PubMed1997

Identification of essential aspartic acid and histidine residues of hormone-sensitive lipase: apparent residues of the catalytic triad.

It is expected that hormone-sensitive lipase (HSL), like most other lipases and esterases, adopts an alpha/beta-hydrolase fold and has a catalytic triad of serine, aspartic or glutamic acid, and histidine. Recently, we have published a three-dimensional model for the C-terminal catalytic domain of HSL, having an alpha/beta-hydrolase fold and with Ser-423(1), Asp-703 and His-733 in the catalytic triad (Contreras et al. (1996) J. Biol. Chem. 271, 31426-31430). It has been shown that Ser-423, situated in the motif GXSXG, is essential for catalysis (Holm et al. (1994) FEBS Lett. 344, 234-238). The suggested aspartic acid and histidine were here probed by site-directed mutagenesis. Mutants of residues Asp-703 and His-733 are devoid of both lipase and esterase activity, which is not the case for mutants of other tested aspartic acid and histidine residues. Thus, the presented data support the three-dimensional model structure with Asp-703 and His-733 as part of the traid.

Animals↗
PubMed1988

Carney's triad: guidelines for management.

Carney's triad--gastric leiomyosarcoma, pulmonary chondroma, and extra-adrenal paraganglioma--is a syndrome that occurs primarily in young women. To date, 28 patients with at least two of these individually unusual or rare neoplasms have been described. This updated case report of one of the originally described patients with Carney's triad highlights several clinically important features of this unusual syndrome: (1) the multicentricity of both the paragangliomas and the epithelioid leiomyosarcomas, (2) the often indolent progression of metastatic leiomyosarcoma, (3) the potential for late recurrences, and (4) the importance of distinguishing intra-adrenal from periadrenal catecholamine-producing tumors (paragangliomas). Localization of paragangliomas is facilitated by two relatively new techniques--131I-metaiodobenzylguanidine scanning (a scintigraphic technique with high specificity for catecholamine-producing tumors) and two-dimensional echocardiography (which can noninvasively localize and demonstrate the anatomic relationships of aorticopulmonary paragangliomas). In patients with this syndrome, new or recurrent tumors frequently manifest after unusually long asymptomatic intervals. We outline an approach for continued follow-up of patients with one or more of the three neoplasms that constitute the syndrome. Rigorous long-term screening of these patients should not only lead to early recognition and resection of recurrent or new tumors but also enhance our understanding of this intriguing syndrome.

Adrenal Gland Neoplasms↗
PubMed1996

Structure of the human cytomegalovirus protease catalytic domain reveals a novel serine protease fold and catalytic triad.

Proteolytic processing of capsid assembly protein precursors by herpesvirus proteases is essential for virion maturation. A 2.5 A crystal structure of the human cytomegalovirus protease catalytic domain has been determined by X-ray diffraction. The structure defines a new class of serine protease with respect to global-fold topology and has a catalytic triad consisting of Ser-132, His-63, and His-157 in contrast with the Ser-His-Asp triads found in other serine proteases. However, catalytic machinery for activating the serine nucleophile and stabilizing a tetrahedral transition state is oriented similarly to that for members of the trypsin-like and subtilisin-like serine protease families. Formation of the active dimer is mediated primarily by burying a helix of one protomer into a deep cleft in the protein surface of the other.

Amino Acid Sequence↗
PubMed1998

The female athlete triad.

The opportunities for girls and women to play soccer has rapidly grown and gained acceptance in recent years. The benefits of involvement in soccer, both physically and psychologically, are overwhelmingly positive. Despite the benefits, girls and women involved in soccer are also at risk for medical problems as a result of their sports participation. Amenorrhea, disordered eating, and premature osteoporosis are entities known together as The Female Athlete Triad. The triad occurs in all sports and is associated with significant short- and long-term health consequences, and thus remains a concern for all involved in the care of the soccer athlete.

Amenorrhea↗
PubMed2003

Identification and characterisation of the catalytic triad of the alkaliphilic thermotolerant PHA depolymerase PhaZ7 of Paucimonas lemoignei.

The recently discovered extracellular poly[(R)-3-hydroxybutyrate] (PHB) depolymerase PhaZ7 of Paucimonas lemoignei represents the first member of a new subgroup (EC 3.1.1.75) of serine hydrolases with no significant amino acid similarities to conventional PHB depolymerases, lipases or other hydrolases except for a potential lipase box-like motif (Ala-His-Ser136-Met-Gly) and potential candidates for catalytic triad and oxyanion pocket amino acids. In order to identify amino acids essential for activity 11 mutants of phaZ7 were generated by site-directed mutagenesis and expressed in recombinant protease-deficient Bacillus subtilis WB800. The wild-type depolymerase and 10 of the 11 mutant proteins (except for Ser136Cys) were expressed and efficiently secreted by B. subtilis as shown by Western blots of cell-free culture fluid proteins. No PHB depolymerase activity was detected in strains harbouring one of the following substitutions: His47Ala, Ser136Ala, Asp242Ala, Asp242Asn, His306Ala, indicating the importance of these amino acids for activity. Replacement of Ser136 by Thr resulted in a decrease of activity to about 20% of the wild-type level and suggested that the hydroxy group of the serine side chain is important for activity but can be partially replaced by the hydroxy function of threonine. Alterations of Asp256 to Ala or Asn or of the putative serine hydrolase pentapeptide motif (Ala-His-Ser136-Met-Gly) to a lipase box consensus sequence (Gly134-His-Ser136-Met-Gly) or to the PHB depolymerase box consensus sequence (Gly134-Leu135-Ser136-Met-Gly) had no significant effect on PHB depolymerase activity, indicating that these amino acids or sequence motifs were not essential for activity. In conclusion, the PHB depolymerase PhaZ7 is a serine hydrolase with a catalytic triad and oxyanion pocket consisting of His47, Ser136, Asp242 and His306.

Amino Acid Sequence↗
PubMed1997

Prenatal diagnosis of a Currarino triad.

Prenatal diagnosis of the Currarino triad by means of obstetrical ultrasonography is described. Three related cases are presented. A literature review regarding the therapeutic, ultrasound-guided approach are discussed. The Currarino triad is a genetically transmitted syndrome consisting of an anorectal malformation, a sacral boney defect and a presacral mass. Prenatal diagnosis aids the early recognition and surgical management of persistent spinal-rectal fistulas, thus potentially avoiding life-threatening bacterial meningitis. Copyright 1997 Elsevier Science Ireland Ltd.

Journal Article↗
PubMed1993

Ultrastructural connectivity of [leu]5-enkephalin-immunoreactive synapses in the guinea-pig stellate ganglion: involvement of spines and triads.

The ultrastructure of [leu]5-enkephalin-immunoreactive (ENK-IR) nerve fibres in the guinea-pig stellate ganglion was studied by means of pre-embedding immunohistochemistry. ENK-immunoreactivity was primarily contained within large dense core vesicles (91 +/- 21 nm in diameter; n = 259) but was absent from small clear vesicles (47 +/- 9 nm; n = 488) within the same nerve terminal that were concentrated at presynaptic regions. Thus, fast synaptic transmission mediated by ENK-IR terminals most probably does not involve [leu]5-enkephalin which may be released parasynaptically. Evaluating a total number of 123 synapses involving an ENK-IR presynaptic nerve ending, 47% terminated upon a spine, 46% upon a dendritic shaft, and 7% directly addressed a soma of a postganglionic neuron. In 30% of axo-dendritic synapses and 33% of axo-somatic synapses, non-immunoreactive dendrites or somata being postsynaptic to an ENK-IR terminal were in direct but non-synaptic contact to another dendrite/soma. Such arrangements are termed "triads". In view of the current hypotheses concerning the function of spines and triads, these findings indicate that ENK-IR terminals within the guinea-pig stellate ganglion may be involved in the generation of long-lasting synaptic events and modulation of non-synaptic intraganglionic communication.

Animals↗
PubMed1998

Catalytic triads and their relatives.

Interactions among the residues in the serine protease Asp-His-Ser catalytic triad, in the special environment of the enzyme-substrate complex, activate the nucleophilic potential of the seryl O gamma. In the subtilisin and trypsin families, the composition and arrangement of the catalytic triad do not vary significantly. However, the mechanisms of action of many other hydrolytic enzymes, which target a wide range of substrates, involve nucleophilic attack by a serine (or threonine) residue. Review of these enzymes shows that the acid-base-ser/thr pattern of catalytic residues is generally conserved, although the individual acids and bases can vary. The variations in sequence and organization illustrate the adaptability shown by proteins in generating catalytic stereochemistry on different main-chain frameworks.

Amino Acid Sequence↗
PubMed1998

Activation of Bacillus licheniformis alpha-amylase through a disorder-->order transition of the substrate-binding site mediated by a calcium-sodium-calcium metal triad.

BACKGROUND: The structural basis as to how metals regulate the functional state of a protein by altering or stabilizing its conformation has been characterized in relatively few cases because the metal-free form of the protein is often partially disordered and unsuitable for crystallographic analysis. This is not the case, however, for Bacillus licheniformis alpha-amylase (BLA) for which the structure of the metal-free form is available. BLA is a hyperthermostable enzyme which is widely used in biotechnology, for example in the breakdown of starch or as a component of detergents. The determination of the structure of BLA in the metal-containing form, together with comparisons to the apo enzyme, will help us to understand the way in which metal ions can regulate enzyme activity. RESULTS: We report here the crystal structure of native, metal-containing BLA. The structure shows that the calcium-binding site which is conserved in all alpha-amylases forms part of an unprecedented linear triadic metal array, with two calcium ions flanking a central sodium ion. A region around the metal triad comprising 21 residues exhibits a conformational change involving a helix unwinding and a disorder-->order transition compared to the structure of metal-free BLA. Another calcium ion, not previously observed in alpha-amylases, is located at the interface between domains A and C. CONCLUSIONS: We present a structural description of a major conformational rearrangement mediated by metal ions. The metal induced disorder-->order transition observed in BLA leads to the formation of the extended substrate-binding site and explains on a structural level the calcium dependency of alpha-amylases. Sequence comparisons indicate that the unique Ca-Na-Ca metal triad and the additional calcium ion located between domains A and C might be found exclusively in bacterial alpha-amylases which show increased thermostability. The information presented here may help in the rational design of mutants with enhanced performance in biotechnological applications.

Bacillus↗
PubMed2003

Catalytic triad of intracellular poly(3-hydroxybutyrate) depolymerase (PhaZ1) in Ralstonia eutropha H16.

The amino acid sequence of an intracellular poly[D(-)-3-hydroxybutyrate] (PHB) depolymerase (PhaZ1) from Ralstonia eutropha H16 was compared with the sequences of various proteins using the BLAST search. It showed a number of matches including with intracellular PHB depolymerases, conserved hypothetical proteins, and PHB synthases. From an alignment of these proteins, we constructed nine mutants: C87A, S118A, H120Q, C183A, C183S, D355A, D356A, C370A, and H388Q. The C183A, D355A, and H388Q mutants lost their activities, but C183S and the other mutants did not. C183, D355, and H388 in PhaZ1 were positioned similarly to the amino acids of the catalytic triad of PHB synthase. These results indicated that C183, D355, and H388 make up the catalytic triad of PhaZ1.

Journal Article↗