Adoption of a Urologic Oncology Perioperative Surgical Home is Associated with Decreased Total Length of Stay: A Pilot Study.

INTRODUCTION: Urologists partnered with anesthesiologists to implement a model of perioperative and postoperative care known as the multidisciplinary perioperative surgical home in order to improve the quality and efficiency of care. We describe early outcomes associated with implementation of the perioperative surgical home. METHODS: Retrospective chart review was performed of patients at a single institution undergoing radical prostatectomy, radical cystectomy, partial nephrectomy and radical nephrectomy from January 2014 to March 2016. Outcomes measured were length of stay and 30-day reoperation, readmission, unexpected intensive care unit admission and mortality rates. Statistical analysis was performed using the independent samples Mann-Whitney U test and Fisher exact test with p <0.05 considered significant. Univariate and multivariate analyses were performed to determine whether implementation of the perioperative surgical home was associated with improved outcomes. RESULTS: Length of hospital stay decreased from 4.79 to 3.19 days and 30-day complication rate decreased from 15.3% to 5.7% after implementation of the perioperative surgical home (p <0.01 for both). There was no change in the 30-day readmission rate. On multivariate analysis surgery occurring after perioperative surgical home implementation was associated with decreased length of stay (p = 0.008). The direct cost savings resulting from this length of stay reduction totaled $1,245,585 for the study period. CONCLUSIONS: The adoption of a perioperative surgical home is associated with a significantly decreased postoperative hospital stay and 30-day complication rate for urologic oncology cases.

Mucosal tolerance to brain antigens preserves endogenous TGFß-1 and improves neurological outcomes following experimental craniotomy.

Intracranial surgery causes brain damage from cortical incisions, intraoperative hemorrhage, retraction, and electrocautery; collectively these injuries have recently been coined surgical brain injury (SBI). Inflammation following SBI contributes to neuronal damage. This study develops T-cells that are immunologically tolerant to brain antigen via the exposure of myelin basic protein (MBP) to airway mucosa. We hypothesize that these T-cells will migrate to the site of corticotomy, secrete immunosuppressive cytokines, such as TGFß1, reduce inflammation, and improve neurological outcomes following SBI. A standard model for SBI was used for this experiment. C57 mice were divided into six groups: SHAM+Vehicle, SHAM+Ovalbumin, SHAM+MBP, SBI+Vehicle, SBI+OVA, and SBI+MBP. Induction of mucosal tolerance to vehicle, ovalbumin, or MBP was performed prior to SBI. Neurological scores and TBFß1 cytokine levels were measured 48 h postoperatively. Mice receiving craniotomy demonstrated a reduction in neurological score. Animals tolerized to MBP (SBI+MBP) had better postoperative neurological scores than SBI+Vehicle and SBI+OVA. SBI inhibited the cerebral expression TGFß1 in PBS and OVA treated groups, whereas MBP treated-animals preserved preoperative levels. Mucosal tolerance to MBP leads to significant improvement in neurological outcome that is associated with the preservation of endogenous levels of brain TGFß1.

Inhibition of a protein-protein interaction between INI1 and c-Myc by small peptidomimetic molecules inspired by Helix-1 of c-Myc: identification of a new target of potential antineoplastic interest.

c-Myc is a transcription modulator proto-oncogene. When overexpressed, it becomes an important contributor to the multi-hit process of malignant transformation. In two earlier papers in this journal (see refs. 19 , 20) we reported that retro-inverso peptidomimetic molecules inspired by the Helix-1 of c-Myc motif could be sequence-specific antiproliferative agents active in the low micromolar range. We also found that our peptides were not opening the four-alpha-helix Myc:Max bundle. Their antiproliferative activity in cancer cell lines needs the presence of side chains projecting outside of the bundle in the corresponding native H1 motif. This observation suggested interference with an external partner. In this study we investigated the INI1:Myc interaction. INI1 is a subunit of the SWI/SNF complex (component of the enhanceosome surrounding Myc:Max heterodimer). The INI1:Myc interaction was confirmed via pull down, ELISA, and fluorescence anisotropy assays. According to the length of INI1 fragments used, we calculated Kds ranging between 1.3x10(-6) and 4.8x10(-7) M. The three different techniques applied showed that the INI1:Myc interaction was also the target of our retro-inverso peptidomimetic molecules, which seem to bind specifically at INI1. A Myc binding, 21aa INI1 fragment (minimum interacting sequence), could inspire the synthesis of a new class of more selective c-Myc inhibitors.

A structural characterization of the interactions between titin Z-repeats and the alpha-actinin C-terminal domain.

Titin and alpha-actinin, two modular muscle proteins, are with actin the major components of the Z-band in vertebrate striated muscles where they serve to organize the antiparallel actin filament arrays in adjacent sarcomeres and to transmit tension between sarcomeres during activation. Interactions between titin and alpha-actinin have been mainly localized in a 45-amino acid multiple motif (Z-repeat) in the N-terminal region of titin and the C-terminal region of alpha-actinin. In this study, we provide the first quantitative characterization of alpha-actinin-Z-repeat recognition and dissect the interaction to its minimal units. Different complementary techniques, such as circular dichroism, calorimetry, and nuclear magnetic spectroscopy, were used. Two overlapping alpha-actinin constructs (Act-EF34 and Act-EF1234) containing two and four EF-hand motifs, respectively, were produced, and their folding properties were examined. Complex formation of Act-EF34 and Act-EF1234 with single- and double-Z-repeat constructs was studied. Act-EF34 was shown quantitatively to be necessary and sufficient for binding to Z-repeats, excluding the presence of additional high-affinity binding sites in the remaining part of the domain. The binding affinities of the different Z-repeats for Act-EF34 range from micromolar to millimolar values. The strongest of these interactions are comparable to those observed in troponin C-troponin I complexes. The binding affinities for Act-EF34 are maximal for Zr1 and Zr7, the two highly homologous sequences present in all muscle isoforms. No cooperative or additional contributions to the interaction were observed for Z-repeat double constructs. These findings have direct relevance for evaluating current models of Z-disk assembly.

SMN tudor domain structure and its interaction with the Sm proteins.

Spinal muscular atrophy (SMA) is a common motor neuron disease that results from mutations in the Survival of Motor Neuron (SMN) gene. The SMN protein plays a crucial role in the assembly of spliceosomal uridine-rich small nuclear ribonucleoprotein (U snRNP) complexes via binding to the spliceosomal Sm core proteins. SMN contains a central Tudor domain that facilitates the SMN-Sm protein interaction. A SMA-causing point mutation (E134K) within the SMN Tudor domain prevents Sm binding. Here, we have determined the three-dimensional structure of the Tudor domain of human SMN. The structure exhibits a conserved negatively charged surface that is shown to interact with the C-terminal Arg and Gly-rich tails of Sm proteins. The E134K mutation does not disrupt the Tudor structure but affects the charge distribution within this binding site. An intriguing structural similarity between the Tudor domain and the Sm proteins suggests the presence of an additional binding interface that resembles that in hetero-oligomeric complexes of Sm proteins. Our data provide a structural basis for a molecular defect underlying SMA.

Endothelin 1 transcription is controlled by nuclear factor-kappaB in AGE-stimulated cultured endothelial cells.

Incubation of bovine aortic endothelial cells (BAECs) with erythrocytes from patients with type 2 diabetes induced an increase in endothelin 1 (ET-1) production. The effect of erythrocytes on ET-1 synthesis was dependent on glycemic control. ET-1 levels after incubation with erythrocytes derived from patients with HbA(1c) levels <6% were just half the levels observed after incubation with erythrocytes from patients with HbA(1c) levels >8%. Nepsilon-(carboxymethyl)lysine (CML)-containing protein isolated from patients' erythrocytes induced ET-1, and CML-containing protein-dependent ET-1 induction was blocked by the recombinant decoy peptide soluble receptor for advanced glycation end products (AGEs), which comprises the NH2-terminal Ig domain of the receptor for AGEs. In vitro-generated AGEs induced ET-1 mRNA transcription (nuclear run-on assay and Northern blot) in a time- and dose-dependent manner. Transient transfection of BAECs with a chimeric construct containing the 5' promoter region of the ET-1 gene linked to a reporter gene confirmed that AGE induced ET-1 promoter activity. Electrophoretic mobility shift assay confirmed AGE-inducible binding of members of the nuclear factor-kappab (NF-kappaB) family to a potential binding site at -2,090 bp. Binding was functionally significant because overexpression of the cytoplasmic inhibitor of NF-kappaB or deletion of the NF-kappaB binding site reduced ET-1 induction, whereas overexpression of NF-kappaB p65 induced ET-1 even in the absence of AGEs. Thus, ET-1 transcription is controlled by the AGE-inducible redox-sensitive transcription factor NF-kappaB.

Towards a structural understanding of Friedreich's ataxia: the solution structure of frataxin.

BACKGROUND: Lesions in the gene for frataxin, a nuclear-encoded mitochondrial protein, cause the recessively inherited condition Friedreich's ataxia. It is thought that the condition arises from disregulation of mitochondrial iron homeostasis, with concomitant oxidative damage leading to neuronal death. Very little is, as yet, known about the biochemical function of frataxin. RESULTS: Here, we show that the mature form of recombinant frataxin behaves in solution as a monodisperse species that is composed of a 15-residue-long unstructured N terminus and an evolutionarily conserved C-terminal region that is able to fold independently. The structure of the C-terminal domain consists of a stable seven-stranded antiparallel beta sheet packing against a pair of parallel helices. The structure is compact with neither grooves nor cavities, features that are typical of iron-binding modules. Exposed evolutionarily conserved residues cover a broad area and all cluster on the beta-sheet face of the structure, suggesting that this is a functionally important surface. The effect of two clinically occurring mutations on the fold was checked experimentally. When the mature protein was titrated with iron, no tendency to iron-binding or to aggregation was observed. CONCLUSIONS: Knowledge of the frataxin structure provides important guidelines as to the nature of the frataxin binding partner. The absence of all the features expected for an iron-binding activity, the large conserved area on its surface and lack of evidence for iron-binding activity strongly support an indirect involvement of frataxin in iron metabolism. The effects of point mutations associated with Friedreich's ataxia can be rationalised by knowledge of the structure and suggest possible models for the occurrence of the disease in compound heterozygous patients.

Binding of alpha-actinin to titin: implications for Z-disk assembly.

Titin is an exceptionally large protein (M.Wt. approximately 3 MDa) that spans half the sarcomere in muscle, from the Z-disk to the M-line. In the Z-disk, it interacts with alpha-actinin homodimers that are a principal component of the Z-filaments linking actin filaments. The interaction between titin and alpha-actinin involves repeating approximately 45 amino acid sequences (Z-repeats) near the N-terminus of titin and the C-lobe of the C-terminal calmodulin-like domain of alpha-actinin. The conformation of Z-repeat 7 (ZR7) of titin when complexed with the 73-amino acid C-terminal portion of alpha-actinin (EF34) was studied by heteronuclear NMR spectroscopy using (15)N-labeling of ZR7 and found to be helical over a stretch of 18 residues. Complex formation resulted in the protection of one site of preferential cleavage of EF34 at Phe14-Leu17, as determined by limited proteolysis experiments coupled to mass spectrometry measurements. Intermolecular NOEs show Val16 of ZR7 to be positioned close in space to the backbone of EF34 around Phe14. These observations suggest that the mode of binding of ZR7 to EF34 is similar to that of troponin I to troponin C and of peptide C20W to calmodulin. These complexes would appear to represent a general alternative binding mode of calmodulin-like domains to target peptides.

The three-dimensional structure of the HRDC domain and implications for the Werner and Bloom syndrome proteins.

BACKGROUND: The HRDC (helicase and RNaseD C-terminal) domain is found at the C terminus of many RecQ helicases, including the human Werner and Bloom syndrome proteins. RecQ helicases have been shown to unwind DNA in an ATP-dependent manner. However, the specific functional roles of these proteins in DNA recombination and replication are not known. An HRDC domain exists in both of the human RecQ homologues that are implicated in human disease and may have an important role in their function. RESULTS: We have determined the three-dimensional structure of the HRDC domain in the Saccharomyces cerevisiae RecQ helicase Sgs1p by nuclear magnetic resonance (NMR) spectroscopy. The structure resembles auxiliary domains in bacterial DNA helicases and other proteins that interact with nucleic acids. We show that a positively charged region on the surface of the Sgs1p HRDC domain can interact with DNA. Structural similarities to bacterial DNA helicases suggest that the HRDC domain functions as an auxiliary domain in RecQ helicases. Homology models of the Werner and Bloom HRDC domains show different surface properties when compared with Sgs1p. CONCLUSIONS: The HRDC domain represents a structural scaffold that resembles auxiliary domains in proteins that are involved in nucleic acid metabolism. In Sgs1p, the HRDC domain could modulate the helicase function via auxiliary contacts to DNA. However, in the Werner and Bloom syndrome helicases the HRDC domain may have a role in their functional differences by mediating diverse molecular interactions.

The NH2 terminus of titin spans the Z-disc: its interaction with a novel 19-kD ligand (T-cap) is required for sarcomeric integrity.

Titin is a giant elastic protein in vertebrate striated muscles with an unprecedented molecular mass of 3-4 megadaltons. Single molecules of titin extend from the Z-line to the M-line. Here, we define the molecular layout of titin within the Z-line; the most NH2-terminal 30 kD of titin is located at the periphery of the Z-line at the border of the adjacent sarcomere, whereas the subsequent 60 kD of titin spans the entire width of the Z-line. In vitro binding studies reveal that mammalian titins have at least four potential binding sites for alpha-actinin within their Z-line spanning region. Titin filaments may specify Z-line width and internal structure by varying the length of their NH2-terminal overlap and number of alpha-actinin binding sites that serve to cross-link the titin and thin filaments. Furthermore, we demonstrate that the NH2-terminal titin Ig repeats Z1 and Z2 in the periphery of the Z-line bind to a novel 19-kD protein, referred to as titin-cap. Using dominant-negative approaches in cardiac myocytes, both the titin Z1-Z2 domains and titin-cap are shown to be required for the structural integrity of sarcomeres, suggesting that their interaction is critical in titin filament-regulated sarcomeric assembly.

ATP-independent DNA unwinding by the adenovirus single-stranded DNA binding protein requires a flexible DNA binding loop.

The adenovirus DNA binding protein (DBP) binds cooperatively to single-stranded (ss) DNA and stimulates both initiation and elongation of DNA replication. DBP forms protein filaments via a C-terminal arm that hooks into a neighbouring molecule. This multimerization is the driving force for ATP-independent DNA unwinding by DBP during elongation. Another conserved part of DBP forms an unstructured flexible loop that is probably directly involved in contacting DNA. By making appropriate deletion mutants that do not distort the overall DBP structure, the influence of the C-terminal arm and the flexible loop on the kinetics of ssDNA binding and on DNA replication was studied. Employing surface plasmon resonance we show that both parts of the protein are required for high affinity binding. Deletion of the C-terminal arm leads to an extremely labile DBP-ssDNA complex indicating the importance of multimerization. The flexible loop is also required for optimal stability of the DBP-ssDNA complex, providing additional evidence that this region forms part of the ssDNA-binding surface of DBP. Both deletion mutants are still able to stimulate initiation of DNA replication but are defective in supporting elongation, which may be caused by the fact that both mutants have a reduced DNA unwinding activity. Surprisingly, mixtures containing both mutants do stimulate elongation. Mixing the purified mutant proteins leads to the formation of mixed filaments that have a higher affinity for ssDNA than homogeneous mutant filaments. These results provide evidence that the C-terminal arm and the flexible loop have distinct functions in unwinding during replication. We propose the following model for ATP-independent DNA unwinding by DBP. Multimerization via the C-terminal arm is required for the formation of a protein filament that saturates the displaced strand. A high affinity of a DBP monomer for ssDNA and subsequent local destabilization of the replication fork requires the flexible loop.

Pterin-4a-carbinolamine dehydratase from Pseudomonas aeruginosa: characterization, catalytic mechanism and comparison to the human enzyme.

The three-dimensional structure of pterin-4a-carbinolamine dehydratase (PCD) from Pseudomonas aeruginosa has been solved. Based on this we have investigated the roles of putative active center residues through functional replacement by site-directed mutagenesis. Three histidines, His73, His74 and His91, appear to be involved in dehydration catalysis. The three-dimensional positions of these residues match those of corresponding histidines at the active center of human PCD. Based on the coincidence of catalytic parameters, and on the similar effects induced by the mutations, it is concluded that the substrate binding mode and the reaction mechanisms of bacterial and human PCD are basically identical.

Tissue-specific expression and alpha-actinin binding properties of the Z-disc titin: implications for the nature of vertebrate Z-discs.

Titins are giant filamentous proteins which connect Z-discs and M-lines in the sarcomeres of vertebrate striated muscles. Comparison of the N-terminal region of titin (Z-disc region) from different skeletal and cardiac muscles reveals a 900-residue segment which is expressed in different length variants, dependent on tissue type. When searching for ligands of this differentially expressed domain by a yeast-two hybrid approach, we detected binding to alpha-actinin. The isolated alpha-actinin cDNAs were derived from the C-terminal region of the alpha-actinin isoform (alpha-actinin-2) encoded by the ACTN2 gene. Therefore, the two antiparallel subunits of an alpha-actinin-2 homodimer will attach to actin at their respective C termini, whereas they will bind to the Z-disc titin at their N termini. This may thus explain how alpha-actinins can cross-link antiparallel titin and thin filaments from opposing sarcomeres. The alpha-actinin-2 binding site of the Z-disc titin is located within a sequence of 45-residue repeats, referred to as Z-repeat region. Both the N-terminal and C-terminal Z-repeats have alpha-actinin binding properties and are expressed in all striated muscles. By contrast, the more central Z-repeats are expressed in slow and fast skeletal muscles, as well as embryonic and adult cardiac muscles, in different copy numbers. Such alternative splicing of the Z-disc titin appears to be important for the tissue and fibre type diversity of the Z-disc lattice.

The crystal structure of an intact human Max-DNA complex: new insights into mechanisms of transcriptional control.

BACKGROUND: Max belongs to the basic helix-loop-helix leucine zipper (bHLHZ) family of transcription factors. Max is able to form homodimers and heterodimers with other members of this family, which include Mad, Mxi1 and Myc; Myc is an oncoprotein implicated in cell proliferation, differentiation and apoptosis. The homodimers and heterodimers compete for a common DNA target site (the E box) and rearrangement amongst these dimer forms provides a complex system of transcriptional regulation. Max is also regulated by phosphorylation at a site preceding the basic region. We report here the first crystal structure of an intact bHLHZ protein bound to its target site. RESULTS: The X-ray crystal structure of the intact human Max protein homodimer in complex with a 13-mer DNA duplex was determined to 2.8 A resolution and refined to an R factor of 0.213. The C-terminal domains in both chains of the Max dimer are disordered. In contrast to the DNA observed in complex with other bHLH and bHLHZ proteins, the DNA in the Max complex is bent by about 25 degrees, directed towards the protein. Intimate contacts with interdigitating sidechains give rise to the formation of tetramers in the crystal. CONCLUSIONS: The structure confirms the importance of the HLH and leucine zipper motifs in dimerization as well as the mode of E box recognition which was previously analyzed by X-ray crystallography of shortened constructs. The disorder observed in the C-terminal domain suggests that contacts with additional protein components of the transcription machinery are necessary for ordering the secondary structure. The tetramers seen in the crystal are consistent with the tendency of Max and other bHLHZ and HLH proteins to form higher order oligomers in solution and may play a role in DNA looping. The location of the two phosphorylation sites at Ser1 and Ser10 (the latter is the N-cap of the basic helix) suggests how phosphorylation could disrupt DNA binding.

The bifunctional protein DCoH modulates interactions of the homeodomain transcription factor HNF1 with nucleic acids.

The hepatocyte nuclear factor-1 (HNF1) is a homeodomain transcription factor that binds DNA as a dimer. HNF1 dimers associate with two molecules of DCoH, a bifunctional protein that also has an enzymatic function in the tetrahydrobiopterin regeneration, to form stable heterotetramers also capable of DNA binding. Employing purified, recombinant HNF1, HNF1/DCoH heterotetramers and DCoH homotetramers we investigated whether DCoH affects interactions of HNF1 with nucleic acids. Although we detected no direct binding of DCoH to DNA or RNA, DCoH stabilized HNF1/DNA complexes and promoted interactions with sub-optimal DNA target sequences such as the human alpha1-antitrypsin TATA box region. Importantly, we also observed interactions of HNF1 with RNA, but these interactions were completely abolished when HNF1 was complexed with DCoH. Interestingly, DCoH retains its enzymatic activity while complexed with HNF1. Our results document intermolecular regulation of HNF1 binding to nucleic acids by DCoH.

Location of the active site and proposed catalytic mechanism of pterin-4a-carbinolamine dehydratase.

Based on the recently solved three-dimensional structure of pterin-4a-carbinolamine dehydratase from rat/human liver the involvement of the proposed active-site residues Glu57, Asp60, His61, His62, Tyr69, His79, Arg87 and Asp88 was examined by site-directed mutagenesis. Most of the mutants showed reduced activity, and only the Glu57-->Ala mutant and the His61-->Ala, His62-->Ala double mutant were fully devoid of activity. The dissociation constants of quinonoid 6,6-dimethyl-7,8-dihydropterin were significantly increased for binding to the Glu57-->Ala, His61-->Ala, His62-->Ala single mutants and the His61-->Ala, His62-->Ala double mutant, confirming that His61 and His62 are essential for substrate binding and catalysis. The mechanism of dehydration is proposed to involve base catalysis at the N(5)-H group of the substrate by His61.

A helical arch allowing single-stranded DNA to thread through T5 5'-exonuclease.

THE 5'-exonucleases are enzymes that are essential for DNA replication and repair. As well as their exonucleolytic action, removing nucleotides from the 5'-end of nucleic acid molecules such as Okazaki fragments, many 5'-3'-exonucleases have been shown to possess endonucleolytic activities. T5 5'-3'-exonuclease shares many similarities with the amino terminal of eubacterial DNA polymerases, although, unlike eubacteria, phages such as T5, T4 and T7 express polymerase and 5'-exonuclease proteins from separate genes. Here we report the 2.5-A crystal structure of the phage T5 5'-exonuclease, which reveals a helical arch for binding DNA. We propose a model consistent with a threading mechanism in which single-stranded DNA could slide through the arch, which is formed by two helices, one containing positively charged, and the other hydrophobic, residues. The active site is at the base of the arch, and contains two metal-binding sites.