Development and Validation of a Risk-Adapted Scoring Model for Metachronous Upper Tract Urothelial Carcinoma following Radical Cystectomy.

PURPOSE: The incidence and risk factors for metachronous upper tract urothelial carcinoma (UTUC) following radical cystectomy (RC) remain incompletely defined, which has limited the ability to individualize postoperative surveillance. MATERIALS AND METHODS: A retrospective review of 2 institutional registries was performed to identify patients undergoing RC for urothelial carcinoma. Multivariable Cox proportional hazard models for metachronous post-RC UTUC were developed in one institutional data set and validated in the second institutional data set. A post-RC UTUC risk score was then developed from these models. RESULTS: A total of 3,170 RC patients were included from the training cohort and 959 RC patients from the validation cohort. At a median followup after RC of 4.6 years (IQR 2.1-8.7), 167 patients were diagnosed with UTUC. On multivariable analysis in the training cohort, risk factors for metachronous UTUC were the presence of positive urothelial margin (HR 2.60, p <0.01), history of bacillus Calmette-Guérin treatment prior to RC (HR 2.20, p <0.01), carcinoma in situ at RC (HR 2.01, p <0.01) and pre-RC hydronephrosis (HR 1.48, p=0.04). These factors had similar discriminative capacity in the training and validation cohorts (C-statistic 0.71 and 0.73, respectively). A UTUC risk score was developed with these variables which stratified patients into low (0 points), intermediate (1-3 points), and high risk (4+ points) for post-RC UTUC, with respective 5-year UTUC-free survivals of 99%, 96%, 89% in the training cohort and 98%, 96%, and 91% in the validation cohort. CONCLUSIONS: We developed and validated a risk score for post-RC UTUC that may optimize UTUC surveillance protocols after RC.

Open-label sildenafil treatment of partial and non-responders to double-blind treatment in men with antidepressant-associated sexual dysfunction.

Fifty partial and non-responders (Clinical Global Impression-Sexual Function (CGI-SF) score>2), out of 76 men who completed a 6-week, double-blind, placebo-controlled trial of sildenafil treatment for serotonergic antidepressant-associated sexual dysfunction, were eligible for an additional 6-week trial of open-label sildenafil (50 mg adjustable to 100 mg) under the same protocol, with blind maintained to initial assignment. Participation (double-blind and open-label) required major depressive disorder in remission (MDD-R) and continuing antidepressant medication. Forty-three entered open-label study: 16/17 initially randomized to sildenafil (sildenafil/sildenafil) and 27/33 initially randomized to placebo (placebo/sildenafil). Thirty-five of 43 (81%) achieved full response (CGI-SF

Detection and consequences of recombinant protein isoforms: implications for biological potency.

Various types of structural variants have been observed in recombinant DNA - derived products. These isoforms include variations in post translational carbohydrate modifications where variations in site occupancy or unoccupied sites may occur. In addition, varying degrees of C-terminal processing and N-terminal substitutions have been observed. Isoforms may also be generated during processing and can include aggregated and/or chemically modified forms of the protein. Sophisticated analytical techniques exist for the identification and characterization of these structural variants. Several strategies have been used to isolate or enrich the isoform before molecular characterization. However, the effect these structural variations have on the biological activity of the product is less well understood. This may, in part, be due to the specificity and variability of the bioassay employed. This presentation describes the isolation and characterization of specific molecular isoforms for a monoclonal antibody product as well as an assessment of effects on biological activity.

The ABRF-MIRG'02 study: assembly state, thermodynamic, and kinetic analysis of an enzyme/inhibitor interaction.

Fully characterizing the interactions involving biomolecules requires information on the assembly state, affinity, kinetics, and thermodynamics associated with complex formation. The analytical technologies often used to measure biomolecular interactions include analytical ultracentrifugation (AUC), isothermal titration calorimetry (ITC), and surface plasmon resonance (SPR). In order to evaluate the capabilities of core facilities to implement these technologies, the Association of Biomolecular Resource Facilities (ABRF) Molecular Interactions Research Group (MIRG) developed a standardized model system and distributed it to a panel of AUC, ITC, and SPR operators. The model system was composed of a well-characterized enzyme-inhibitor pair, namely bovine carbonic anhydrase II (CA II) and 4-carboxybenzenesulfonamide (CBS). Study participants were asked to measure one or more of the following: (1) the molecular mass, homogeneity, and assembly state of CA II by AUC; (2) the affinity and thermodynamics for complex formation by ITC; and (3) the affinity and kinetics of complex formation by SPR. The results from this study provide a benchmark for comparing the capabilities of individual laboratories and for defining the utility of the different instrumentation.

Formulary restriction of selective serotonin reuptake inhibitors for depression: potential pitfalls.

The American healthcare market is currently estimated at more than 900 billion US dollars with double digit rising costs per year. Psychotropic agent costs have more than kept pace with market increases. Medication acquisition costs are an obvious focus for limiting costs in various care systems. Restrictive formularies are a common method of attempting to limit costs. To support our opinion that a single agent is ill advised, we explored the available evidence on the intended and unintended consequences of having a single or exclusive selective serotonin reuptake inhibitor (SSRI) on a formulary. Central to this position is an assumption of the interchangeability of SSRIs; we examined the evidence for and against this through a model to determine the probability of interchangeability. We conclude that the practice of having a single SSRI on the formulary for a healthcare plan seems ill founded. Patients who switch antidepressants remain in treatment 50% longer and cost approximately 50% more to treat in a more costly treatment setting. Giving the primary care physician several antidepressant choices can provide more options to continue treatment of his or her patient in the less expensive primary care setting. In terms of cost containment, formulary restrictions are far more likely to have the opposite effect.

Modification of the Fc region of a primatized IgG antibody to human CD4 retains its ability to modulate CD4 receptors but does not deplete CD4(+) T cells in chimpanzees.

Keliximab, a Primatized IgG1 CD4 mAb, was reconfigured to an IgG4 antibody. The gamma4 constant region was further modified by substituting glutamic acid for serine at position 235 in the CH2 domain (IgG4-E), to remove residual binding to Fcgamma receptors, and substitution of serine with proline at position 228 in the hinge region (IgG4-PE) for greater stability. Pharmacokinetic analysis in rats gave a t(1/2) of approximately 4 days for IgG4-E and 9 days for IgG4-PE, consistent with a greater stability of the IgG4-PE molecule. The effects on T cell subsets were assessed in chimpanzees given escalating doses of IgG4-PE: 0.05 mg/kg on Day 16, 1.5 mg/kg dose on Day 43, and 15 mg/kg on Day 85. Receptor modulation was observed at the two highest doses, but no depletion of T cells at any dose. The in vitro and in vivo results demonstrate the potential of this IgG4-PE mAb for use in human trials.

Energetics of the HIV gp120-CD4 binding reaction.

HIV infection is initiated by the selective interaction between the cellular receptor CD4 and gp120, the external envelope glycoprotein of the virus. We used analytical ultracentrifugation, titration calorimetry, and surface plasmon resonance biosensor analysis to characterize the assembly state, thermodynamics, and kinetics of the CD4-gp120 interaction. The binding thermodynamics were of unexpected magnitude; changes in enthalpy, entropy, and heat capacity greatly exceeded those described for typical protein-protein interactions. These unusual thermodynamic properties were observed with both intact gp120 and a deglycosylated and truncated form of gp120 protein that lacked hypervariable loops V1, V2, and V3 and segments of its N and C termini. Together with previous crystallographic studies, the large changes in heat capacity and entropy reveal that extensive structural rearrangements occur within the core of gp120 upon CD4 binding. CD spectral studies and slow kinetics of binding support this conclusion. These results indicate considerable conformational flexibility within gp120, which may relate to viral mechanisms for triggering infection and disguising conserved receptor-binding sites from the immune system.

Measurement of protein interaction bioenergetics: application to structural variants of anti-sCD4 antibody.

This chapter has described a bioenergetic analysis of the interaction of sCD4 with an IgG1 and two IgG4 derivatives of an anti-sCD4 MAb. The MAbs have identical VH and VL domains but differ markedly in their CH and CL domains, raising the question of whether their antigen-binding chemistries are altered. We find the sCD4-binding kinetics and thermodynamics of the MAbs are indistinguishable, which indicates rigorously that the molecular details of the binding interactions are the same. We also showed the importance of using multiple biophysical methods to define the binding model before the bioenergetics can be appropriately interpreted. Analysis of the binding thermodynamics and kinetics suggests conformational changes that might be coupled to sCD4 binding by these MAbs are small or absent.

Secondary structure and structure-activity relationships of peptides corresponding to the subunit interface of herpes simplex virus DNA polymerase.

The interaction of the catalytic subunit of herpes simplex virus DNA polymerase with the processivity subunit, UL42, is essential for viral replication and is thus a potential target for antiviral drug discovery. We have previously reported that a peptide analogous to the C-terminal 36 residues of the catalytic subunit, which are necessary and sufficient for its interaction with UL42, forms a monomeric structure with partial alpha-helical character. This peptide and one analogous to the C-terminal 18 residues specifically inhibit UL42-dependent long chain DNA synthesis. Using multidimensional (1)H nuclear magnetic resonance spectroscopy, we have found that the 36-residue peptide contains partially ordered N- and C-terminal alpha-helices separated by a less ordered region. A series of "alanine scan" peptides derived from the C-terminal 18 residues of the catalytic subunit were tested for their ability to inhibit long-chain DNA synthesis and by circular dichroism for secondary structure. The results identify structural aspects and specific side chains that appear to be crucial for interacting with UL42. These findings may aid in the rational design of new drugs for the treatment of herpesvirus infections.

Self-activation of guanosine triphosphatase activity by oligomerization of the bacterial cell division protein FtsZ.

The essential bacterial cell division protein FtsZ (filamentation temperature-sensitive protein Z) is a distant homologue to the eukaryotic cytoskeletal protein tubulin. We have examined the GTP hydrolytic activity of Escherichia coli FtsZ using a real-time fluorescence assay that monitors phosphate production. The GTPase activity shows a dramatic, nonlinear dependence on FtsZ concentration, with activity only observed at enzyme concentrations greater than 1 microM. At 5 microM FtsZ, we have determined a K(m) of 82 microM GTP and a V(max) of 490 nmol of P(i) min(-1) (mg of protein)(-1). Hydrolysis of GTP requires Mg(2+) and other divalent cations substitute only poorly for this requirement. We have compared the concentration dependence of FtsZ GTPase activity with the oligomeric state by use of analytical ultracentrifugation and chemical cross-linking. Equilibrium analytical ultracentrifugation experiments show that FtsZ exists as 68% dimer and 13% trimer at 2 microM total protein concentration. Chemical cross-linking of FtsZ also shows that monomer, dimer, trimer, and tetramer species are present at higher (>2 microM) FtsZ concentrations. However, as shown by analytical centrifugation, GDP-bound FtsZ is significantly shifted to the monomeric state, which suggests that GTP hydrolysis regulates polymer destabilization. We also monitored the effect of nucleotide and metal ion on the secondary structure of FtsZ; nucleotide yielded no evidence of structural changes in FtsZ, but both Mg(2+) and Ca(2+) had significant effects on secondary structure. Taken together, our results support the hypothesis that Mg(2+)-dependent GTP hydrolysis by FtsZ requires oligomerization of FtsZ. On the basis of these results and structural comparisons with the alpha-beta tubulin dimer, GTP is likely hydrolyzed in a shared active site formed between two monomer subunits.

Modeling the pharmacoeconomic cost of three selective serotonin reuptake inhibitors.

The authors present a method for modeling cost data on three selective serotonin reuptake inhibitors (SSRIs)-fluoxetine, paroxetine, and sertraline-from a large clinical outcomes study in a university-affiliated mental health center. Using data from 2,779 patients, average drug cost per day was calculated based on the percentage of patients on each daily dose of each medication. Given no overall significant difference between the SSRIs in effectiveness, the actual average cost per day determined by dose distribution was $1.79 for fluoxetine, $1.41 for paroxetine, and $1.21 for sertraline (using halved 100 mg tablets). The results suggest that cost can serve as one measure to help guide choice of medications.

Antidepressant medication change in a clinical treatment setting: a comparison of the effectiveness of selective serotonin reuptake inhibitors.

BACKGROUND: This investigation focuses on the 3 most frequently used selective serotonin reuptake inhibitors (SSRIs) (paroxetine, fluoxetine, sertraline) and examines the rate of medication switches as a measure of effectiveness. We answer 2 questions: (1) What is the likelihood that a patient starting treatment with an SSRI will complete treatment with the same agent? and (2) Depending on the initial SSRI agent used, do patients switch at different frequencies? METHOD: A retrospective chart review was performed on 2779 patients treated in a university outpatient clinic from March 1995 to January 1997. Of these, 263 patients given antidepressants were randomly selected: 214 were prescribed SSRIs; 24, novel antidepressants; and 25, tricyclic antidepressants. RESULTS: There was no significant difference in rate of switching between the different classes of antidepressant (p = .1) nor between drugs within the SSRI class (p = .513). When medication change was the independent factor, significant differences between the groups were total time in treatment and number of visits (p < .001 and p = .011, respectively). Age, education, and Clinical Global Impressions-Severity of Illness scale scores (admission, discharge, and change) were not significantly different between the groups. CONCLUSION: Approximately 25% of patients started with an SSRI will switch to another antidepressant in the course of their treatment. The SSRIs appear to be equivalent in effectiveness. They are not interchangeable, because patients who discontinue one SSRI for lack of tolerability or response can generally be treated effectively with another.

Sildenafil for women patients with antidepressant-induced sexual dysfunction.

In an open study, sildenafil (Viagra) was prescribed for nine women outpatients who reported sexual dysfunction induced by antidepressant medication, primarily selective serotonin reuptake inhibitors. A 50 mg dose of sildenafil was prescribed, and patients were instructed to take it approximately one hour before sexual activity. They were told to increase the dose to 100 mg on the next occasion if they experienced a partial response or a lack of response to sildenafil. The nine patients, all of whom had experienced either anorgasmia or delayed orgasm with or without associated disturbances, reported significant reversal of sexual dysfunction, usually with the first dose of 50 mg of sildenafil.

Employing new grads: a plan for success.

The authors describe an elegant goal-driven program designed to prepare new nursing graduates to function optimally on a hospital unit by focusing first on their security and affiliative needs [belonging], and subsequently on their professional skill and knowledge acquisition. This developmental program has both a clear timeline and structure as well as well defined role expectations for the experienced RN guide/mentor, the orientee, and the unit's nurse manager and staff. The guide/mentors are carefully selected and prepared for their new roles as well. Shared goal-setting sessions are held weekly, along with three major evaluations during the first 90 days, with less frequent updates throughout the following year. This frequent feedback, reinforcement, and fine-tuning of goals allows the new graduate to gradually take on the full work load by the end of week 12 without feeling as overwhelmed or inadequate as those who are less carefully developed.

Sildenafil for iatrogenic serotonergic antidepressant medication-induced sexual dysfunction in 4 patients.

OBJECTIVE: To evaluate the effect of sildenafil on iatrogenic serotonergic antidepressant-induced sexual dysfunction. METHOD: Four outpatients (2 men, 2 women) who developed sexual dysfunction (erectile impotence, anorgasmia) during treatment with a serotonin reuptake inhibitor antidepressant for psychiatric disorder were selected. Each subject was initially prescribed sildenafil 50 mg to be taken approximately 1 hour before sexual activity. The dose was increased to 100 mg for a partial or failed response. RESULTS: Four cases are detailed in case report fashion. All 4 had rapid reversal of their sexual dysfunction, usually with the first dose. Reversal equates to 1 successful use of sildenafil in each of 2 patients and 3 uses in 2 patients. CONCLUSION: Sildenafil may be an effective treatment for serotonergic antidepressant-induced sexual dysfunction and deserves further evaluation in randomized placebo-controlled studies.

Herpesvirus entry mediator ligand (HVEM-L), a novel ligand for HVEM/TR2, stimulates proliferation of T cells and inhibits HT29 cell growth.

Herpesvirus entry mediator (HVEM), a member of the tumor necrosis factor (TNF) receptor family, mediates herpesvirus entry into cells during infection. Upon overexpression, HVEM activates NF-kappaB and AP-1 through a TNF receptor-associated factor (TRAF)-mediated mechanism. Using an HVEM-Fc fusion protein, we screened soluble forms of novel TNF-related proteins derived from an expressed sequence tag data base. One of these, which we designated HVEM-L, specifically bound to HVEM-Fc with an affinity of 44 nM. This association was confirmed with soluble and membrane forms of both receptor and ligand. HVEM-L mRNA is expressed in spleen, lymph nodes, macrophages, and T cells and encodes a 240-amino acid protein. A soluble, secreted form of the protein stimulates proliferation of T lymphocytes during allogeneic responses, inhibits HT-29 cell growth, and weakly stimulates NF-kappaB-dependent transcription.