Predicting the rate of cognitive decline in aging and early Alzheimer disease.

OBJECTIVES: To determine prognostic factors affecting the course of Alzheimer disease (AD) and to determine the role of region-specific brain volumes as predictors of cognitive decline. METHODS: Longitudinal data from 166 normal elderly individuals and 59 early AD patients were analyzed. Brain volumes were extracted from MRI scans using semiautomated recursive segmentation methods. Prognostic factors were considered significant if they had a significant effect on the rate of cognitive decline. RESULTS: In multivariate analysis, higher Clinical Dementia Rating Scale (CDR) score at entry was a significant prognostic factor for an increased rate of cognitive decline. Significant prognostic factors within the baseline CDR = 0 group were base rate of progression and percent total high signal intensity (HSI), percent ventricular, and percent CSF volumes. Base rate of progression, family history, and percent ventricular volume were significant prognostic factors within the CDR = 0.5 group and APOE had a marginally significant effect on the rate of cognitive decline in the CDR = 1 group. CONCLUSIONS: Percent total HSI, ventricular, and total CSF volume measures can independently predict the rate of cognitive decline and improve the predictive power of statistical models that use only clinical data. Brain volumetric measures from MRI can be used to estimate the rate of cognitive decline even among normal elderly individuals and thus may aid in the prediction of time of onset of disease.

The influence of gender on survival and tumor recurrence following adjuvant therapy of completely resected stages II and IIIa non-small cell lung cancer.

This study evaluates the influence of gender on survival and tumor recurrence following adjuvant therapy of completely resected stages II and IIIa non-small cell lung cancer (NSCLC). The Eastern Cooperative Oncology Group conducted a randomized prospective trial of adjuvant therapy in patients with completely resected stages II and IIIa NSCLC. A laboratory correlative study assessed the prevalence and prognostic significance of p53 and K-ras mutations. Patients were randomized to receive either radiotherapy (RT) alone or four cycles of cisplatin and VP-16 administered concurrently with radiotherapy (CRT). Median survival was 35 months for the 285 men and 41 months for the 203 women enrolled in the study (P = 0.12). The relative risk (RR) of death for men vs women was 1.19 (95% confidence interval [CI], 0.95-1.49). Median survival of the 147 men and 95 women randomized to the RT arm was 39 months each (P = 0.35). Median survival of the 138 men and 108 women randomized to the CRT arm was 30 and 42 months, respectively (P = 0.18). Disease recurrence patterns were similar between the genders. Univariate and multivariate analyses demonstrated improved survival for women with tumors of non-squamous histology (P < 0.01). The distribution of p53 and K-ras mutations was similar between the genders and had no influence on survival. Gender does not influence survival following adjuvant RT or CRT administered to patients with completely resected stages II and IIIa NSCLC. However, women with non-squamous histology have increased survival when compared to men.

Phase I/II trial of outpatient docetaxel, cisplatin, 5-fluorouracil, leucovorin (opTPFL) as induction for squamous cell carcinoma of the head and neck (SCCHN).

The purpose of this study was to establish the maximum tolerated dose (MTD) of docetaxel in an outpatient docetaxel (T), cisplatin (P), 5-fluorouracil (5-FU) (F), and leucovorin (L) (opTPFL) regimen and to obtain preliminary assessment of opTPFL efficacy. Thirty-four patients with stage III or IV squamous cell carcinoma of the head and neck were treated with opTPFL. Docetaxel was escalated from 60 to 95 mg/m(2) in combination with 100 mg/m(2) cisplatin intravenous bolus, and 2,800 mg/m(2) 5-FU continuous infusion and 2,000 mg/m(2) leucovorin continuous infusion with prophylactic growth factors and antibiotics. Patients who achieved a complete (CR) or partial (PR) response to three cycles received definitive twice-daily radiation therapy. A total of 97 cycles were administered to 34 patients. The major acute toxicities were neutropenia and mucositis. The MTD of docetaxel was 90 mg/m(2) . Seventy-seven of 97 cycles of were administered on an outpatient basis. The overall clinical response rate to opTPFL was 94%, with 44% CRs and 50% PRs. The MTD of opTPFL is 90 mg/m(2) docetaxel. Outpatient administration of opTPFL is tolerable, feasible, and does not alter the ability to administer definitive radiation therapy on schedule.

Genome-wide pathway analysis and visualization using gene expression data.

Visualization of results for high performance computing pose special problems due to the complexity and the volume of data these systems manipulate. We present an approach for visualization of c-DNA microarray gene expression data in metabolic and regulatory pathways using multi-resolution animation at different levels of detail. We describe three scoring functions to characterize pathways at the transcriptional level based on gene expression, coregulation and cascade effect. We also assess the significance of each pathway score on the basis of their biological connotation.

Hypothyroidism incidence after multimodality treatment for stage III and IV squamous cell carcinomas of the head and neck.

PURPOSE: Treatment of head-and-neck cancer patients with surgery, radiotherapy (RT), and chemotherapy has been associated with posttherapy hypothyroidism (HT). We evaluated the rate of posttherapy HT in patients with locally advanced squamous cell carcinoma of the head and neck, treated with multimodality therapy to determine which factors might predict this condition and at what interval the condition developed. METHODS: We reviewed the prospectively collected thyroid function data of patients treated with sequential chemotherapy, RT, and neck dissection. The incidence of posttherapy HT was estimated. The patient, tumor, and treatment factors possibly associated with HT were evaluated. RESULTS: Of 203 patients, 118 had data adequate for evaluation. HT developed in 45% at a median of 24.4 months after therapy. HT occurred in 14% and 27% of patients at 6 months and 1 year after treatment, respectively. Univariate and multivariate analyses of sex, age, RT dose, RT fractionation, T and N stage, tumor site, and neck dissection failed to identify a clinically relevant risk factor. CONCLUSIONS: A high number of patients undergoing aggressive organ-sparing multimodality therapy for advanced squamous cell carcinoma of the head and neck are at risk for subsequent HT. We recommend that all patients definitively irradiated to the head and neck region undergo frequent serum thyroid-stimulating hormone screening for HT, beginning 6 months after RT.

Regulation of the properties of the heme-NO complexes in nitric-oxide synthase by hydrogen bonding to the proximal cysteine.

Nitric-oxide synthase (NOS) catalyzes the formation of NO and citrulline from l-arginine and oxygen. However, the NO so formed has been found to auto-inhibit the enzymatic activity significantly. We hypothesized that the NO reactivity is in part controlled by hydrogen bonding between the conserved tryptophan residue (position 409 in the neuronal isoform of NOS (nNOS)) and the cysteine residue that forms the proximal bond to the heme. By using resonance Raman spectroscopy and NO as a probe of the heme environment, we show that in the W409F and W409Y mutants of the oxygenase domain of the neuronal enzyme (nNOSox), the Fe-NO bond in the Fe3+NO complex is weaker than in the wild type enzyme, consistent with the loss of a hydrogen bond on the sulfur atom of the proximal cysteine residue. The weaker Fe-NO bond in the W409F and W409Y mutants might result in a faster rate of NO dissociation from the ferric heme in the Trp-409 mutants as compared with the wild type enzyme, which could contribute to the lower accumulation of the inhibitory NO-bound complexes observed during catalysis with the Trp-409 mutants (Adak, S., Crooks, C., Wang, Q., Crane, B. R., Tainer, J. A., Getzoff, E. D., and Stuehr, D. J. (1999) J. Biol. Chem. 274, 26907-26911). The optical and resonance Raman spectra of the Fe2+NO complexes of the Trp-409 mutants differ from those of the wild type enzyme and indicate that a significant population of a five-coordinate Fe2+NO complex is present. These data show that the hydrogen bond provided by the Trp-409 residue is necessary to maintain the thiolate coordination when NO binds to the ferrous heme. Taken together our results indicate that the heme environment on the proximal side of nNOS is critical for the formation of a stable iron-cysteine bond and for the control of the electronic properties of heme-NO complexes.

Quality of life assessment in advanced non-small-cell lung cancer patients undergoing an accelerated radiotherapy regimen: report of ECOG study 4593. Eastern Cooperative Oncology Group.

PURPOSE: To prospectively evaluate the quality of life (QOL) before, at completion, and after therapy for patients receiving an accelerated fractionation schedule of radiotherapy for advanced, unresectable non-small-cell lung cancer in a Phase II multi-institutional trial. METHODS AND MATERIALS: The Functional Assessment of Cancer Therapy-Lung (FACT-L) patient questionnaire was used to score the QOL in patients enrolled in the Eastern Cooperative Oncology Group Phase II trial (ECOG 4593) of hyperfractionated accelerated radiotherapy in non-small-cell lung cancer. Radiotherapy (total dose 57.6 Gy in 36 fractions) was delivered during 15 days, with three radiation fractions given each treatment day. The protocol was activated in 1993, and 30 patients had accrued by November 1995. The FACT-L questionnaire was administered at study entry (baseline), on the last day of radiotherapy (assessment 2), and 4 weeks after therapy (assessment 3). The FACT-L includes scores for physical, functional, emotional, and social well-being (33 items), and a subscale of lung cancer symptoms (10 additional items). The summation of the physical, functional, and lung cancer symptom subscales (21 items) constitutes the Trial Outcome Index (TOI), considered the most clinically relevant outcome measure in lung cancer treatment trials. RESULTS: The FACT-L completion rates at the designated study time points were as follows: baseline, 30 of 30 (100%); assessment 2, 29 (97%) of 30; and assessment 3, 24 (80%) of 30. At treatment completion, statistically significant declines in QOL scores were noted, compared with baseline for physical and functional well-being. Emotional well-being scores improved at both assessment 2 and assessment 3. The physical and functional scores returned approximately to baseline values at assessment 3. The change in TOI score was evaluated as a function of the clinical response to treatment, toxicity grade, and survival; no clear association was noted. A trend for the largest decrease in QOL was noted for patient groups with shorter survival times. The mean change in the TOI score from baseline to assessment 3 was -8.96 for patients surviving < 52 weeks vs. -0.95 for those surviving > 52 weeks. CONCLUSIONS: The FACT-L questionnaire can be successfully administered to non-small-cell lung cancer patients enrolled in a prospective Phase II trial of accelerated radiation fractionation. The decrement in physical and functional QOL during treatment returned to baseline level at 4 weeks after treatment. Emotional well-being improved at all time points. A trend was noted for shorter survival times in patients with the largest negative change in TOI score. These data suggest that the clinical use of hyperfractionated accelerated radiotherapy did not cause a significant, long-term decrease in the QOL of the treated patients, and that it is feasible to perform a QOL study of patients enrolled in such a trial.

A phase II study of combined oral uracil and ftorafur with leucovorin for patients with squamous cell carcinoma of the head and neck.

BACKGROUND: The objective of this Phase II study was to define the response rate, safety profile, and toxicity of oral uracil and ftorafur (UFT) with leucovorin (UFT/LV) as a palliative treatment for patients with squamous cell carcinoma of the head and neck (SCCHN). METHODS: Patients with metastatic or recurrent SCCHN with an Eastern Cooperative Oncology Group performance status < 2 and adequate organ function were enrolled in an institutional review board-approved trial. Prior induction or adjuvant chemotherapy was permitted provided 6 months had elapsed since the last chemotherapy. Patients were treated with UFT 300 mg/m(2) per day and leucovorin 90 mg per day administered in three doses daily for 28 days followed by a 7-day break for a 35-day cycle. Planned intrapatient dose modifications were based on individual toxicity. Patients were removed from the study for progression of disease or unacceptable toxicity. RESULTS: One hundred six cycles of UFT/LV had been administered to 42 patients as of January 1, 2000. The most common toxicities, in descending order of incidence, were anemia, pain, fatigue, diarrhea, nausea, mucositis, and anorexia. Clinically significant toxicities attributable to UFT/ LV were primarily gastrointestinal. On an intent-to-treat basis, three patients (7%) achieved a complete response, and six patients (14%) achieved a partial response. The overall response rate was 21% (95% confidence interval, 10--37%). CONCLUSIONS: UFT/LV therapy is feasible in this patient population and is generally well tolerated. Response rates are similar to the rates expected with continuous-infusion 5-fluorouracil. UFT/LV should be studied further both alone and in combination therapy for patients with SCCHN.

Survival analysis with time-varying relative risks: a tree-based approach.

A tree-based method for estimating time-varying effects of baseline patient characteristics on survival is introduced. A Cox-type model for censored survival data is used in which the time-varying relative risks are modelled as piecewise constants. The tree method consists of three steps: 1. Growing the tree, in which a fast algorithm using maximized score statistics is utilized to determine the optimal change points; 2. A pruning algorithm is applied to obtain more parsimonious models; 3. Selection of a final tree, which may be either via bootstrap resampling or based on a measure of explained variation. The piecewise constant model is more suitable for clinical interpretation of the regression parameters than the more continuously time-varying models (spline, loess, etc.) that have been proposed previously.

An essential role of active site arginine residue in iodide binding and histidine residue in electron transfer for iodide oxidation by horseradish peroxidase.

The objective of the present study is to delineate the role of active site arginine and histidine residues of horseradish peroxidase (HRP) in controlling iodide oxidation using chemical modification technique. The arginine specific reagent, phenylglyoxal (PGO) irreversibly blocks iodide oxidation following pseudofirst order kinetics with second order rate constant of 25.12 min(-1) M(-1). Radiolabelled PGO incorporation studies indicate an essential role of a single arginine residue in enzyme inactivation. The enzyme can be protected both by iodide and an aromatic donor such as guaiacol. Moreover, guaiacol-protected enzyme can oxidise iodide and iodide-protected enzyme can oxidise guaiacol suggesting the regulatory role of the same active site arginine residue in both iodide and guaiacol binding. The protection constant (Kp) for iodide and guaiacol are 500 and 10 microM respectively indicating higher affinity of guaiacol than iodide at this site. Donor binding studies indicate that guaiacol competitively inhibits iodide binding suggesting their interaction at the same binding site. Arginine-modified enzyme shows significant loss of iodide binding as shown by increased Kd value to 571 mM from the native enzyme (Kd = 150 mM). Although arginine-modified enzyme reacts with H2O2 to form compound II presumably at a slow rate, the latter is not reduced by iodide presumably due to low affinity binding. The role of the active site histidine residue in iodide oxidation was also studied after disubstitution reaction of the histidine imidazole nitrogens with diethylpyrocarbonate (DEPC), a histidine specific reagent. DEPC blocks iodide oxidation following pseudofirst order kinetics with second order rate constant of 0.66 min(-1) M(-1). Both the nitrogens (delta, epsilon) of histidine imidazole were modified as evidenced by the characteristic peak at 222 nm. The enzyme is not protected by iodide suggesting that imidazolium ion is not involved in iodide binding. Moreover, DEPC-modified enzyme binds iodide similar to the native enzyme. However, the modified enzyme does not form compound II but forms compound I only with higher concentration of H2O2 suggesting the catalytic role of this histidine in the formation and autoreduction of compound I. Interestingly, compound I thus formed is not reduced by iodide indicating block of electron transport from the donor to the compound I. We suggest that an active site arginine residue regulates iodide binding while the histidine residue controls the electron transfer to the heme ferryl group during oxidation.

Topotecan versus observation after cisplatin plus etoposide in extensive-stage small-cell lung cancer: E7593--a phase III trial of the Eastern Cooperative Oncology Group.

PURPOSE: To determine the efficacy of topotecan in combination with standard chemotherapy in previously untreated patients with extensive-stage small-cell lung cancer (SCLC), the Eastern Cooperative Oncology Group (ECOG) conducted a phase III trial. PATIENTS AND METHODS: Eligible patients had measurable or assessable disease and an ECOG performance status of 0 to 2; stable brain metastases were allowed. All patients received four cycles of cisplatin and etoposide every 3 weeks (step 1; PE). Patients with stable or responding disease were then randomized to observation or four cycles of topotecan (1.5 mg/m(2)/d for 5 days, every 3 weeks; step 2). A total of 402 eligible patients were registered to step 1, and 223 eligible patients were registered to step 2 (observation, n = 111; topotecan, n = 112). RESULTS: Complete and partial response rates to induction PE were 3% and 32%, respectively. A 7% response rate was observed with topotecan (complete response, 2%; partial response, 5%). The median survival time for all 402 eligible patients was 9.6 months. Progression-free survival (PFS) from date of randomization on step 2 was significantly better with topotecan compared with observation (3.6 months v 2.3 months; P <.001). However, overall survival from date of randomization on step 2 was not significantly different between the observation and topotecan arms (8.9 months v 9.3 months; P =.43). Grade 4 neutropenia and thrombocytopenia occurred in 50% and 3%, respectively, of PE patients in step 1 and 60% and 13% of topotecan patients in step 2. Grade 4/5 infection was observed in 4.6% of PE patients and 1.8% of topotecan patients. Grade 3/4 anemia developed in 22% of patients who received topotecan. No difference in quality of life between topotecan and observation was observed at any assessment time or for any of the subscale scores. CONCLUSION: Four cycles of PE induction therapy followed by four cycles of topotecan improved PFS but failed to improve overall survival or quality of life in extensive-stage SCLC. Four cycles of standard PE remains an appropriate first-line treatment for extensive-stage SCLC patients with good performance status.

Chimeras of nitric-oxide synthase types I and III establish fundamental correlates between heme reduction, heme-NO complex formation, and catalytic activity.

Neuronal nitric-oxide synthase (nNOS or NOS I) and endothelial NOS (eNOS or NOS III) differ widely in their reductase and nitric oxide (NO) synthesis activities, electron transfer rates, and propensities to form a heme-NO complex during catalysis. We generated chimeras by swapping eNOS and nNOS oxygenase domains to understand the basis for these differences and to identify structural elements that determine their catalytic behaviors. Swapping oxygenase domains did not alter domain-specific catalytic functions (cytochrome c reduction or H(2)O(2)-supported N(omega)-hydroxy-l-arginine oxidation) but markedly affected steady-state NO synthesis and NADPH oxidation compared with native eNOS and nNOS. Stopped-flow analysis showed that reductase domains either maintained (nNOS) or slightly exceeded (eNOS) their native rates of heme reduction in each chimera. Heme reduction rates were found to correlate with the initial rates of NADPH oxidation and heme-NO complex formation, with the percentage of heme-NO complex attained during the steady state, and with NO synthesis activity. Oxygenase domain identity influenced these parameters to a lesser degree. We conclude: 1) Heme reduction rates in nNOS and eNOS are controlled primarily by their reductase domains and are almost independent of oxygenase domain identity. 2) Heme reduction rate is the dominant parameter controlling the kinetics and extent of heme-NO complex formation in both eNOS and nNOS, and thus it determines to what degree heme-NO complex formation influences their steady-state NO synthesis, whereas oxygenase domains provide minor but important influences. 3) General principles that relate heme reduction rate, heme-NO complex formation, and NO synthesis are not specific for nNOS but apply to eNOS as well.

A proximal tryptophan in NO synthase controls activity by a novel mechanism.

The heme of neuronal nitric oxide synthase (nNOS) participates in O2 activation but also binds self-generated NO, resulting in reversible feedback inhibition. We utilized mutagenesis to investigate if a conserved tryptophan residue (Trp409), which engages in pi-stacking with the heme and hydrogen bonds to its axial cysteine ligand, helps control catalysis and regulation by NO. Mutants W409F and W409Y were hyperactive regarding NO synthesis without affecting cytochrome c reduction, reductase-independent N-hydroxyarginine oxidation, or Arg and tetrahydrobiopterin binding. In the absence of Arg electron flux through the heme was slower in the W409 mutants than in wild-type. However, less NO complex accumulated during NO synthesis by the mutants. To understand the mechanism, we compared the kinetics of heme-NO complex formation, rate of heme reduction, kcat prior to and after NO complex formation, NO binding affinity, NO complex stability, and its reaction with O2. During the initial phase of NO synthesis, heme-NO complex formation was three and five times slower in W409F and W409Y, which corresponded to a slower heme reduction. NO complex formation inhibited wild-type turnover 7-fold but reduced mutant turnover less than 2-fold, giving mutants higher steady-state activities. NO binding kinetics were similar among mutants and wild type, although mutants also formed a 417 nm ferrous-NO complex. Oxidation of ferrous-NO complex was seven times faster in mutants than in wild type. We conclude that mutant hyperactivity primarily derives from slower heme reduction and faster oxidation of the heme-NO complex by O2. In this way Trp409 mutations minimize NO feedback inhibition by limiting buildup of the ferrous-NO complex during the steady state. Conservation of W409 among NOS suggests that this proximal Trp may regulate NO feedback inhibition and is important for enzyme physiologic function.

Lack of prognostic significance of p53 and K-ras mutations in primary resected non-small-cell lung cancer on E4592: a Laboratory Ancillary Study on an Eastern Cooperative Oncology Group Prospective Randomized Trial of Postoperative Adjuvant Therapy.

PURPOSE: To determine the prognostic and predictive significance of p53 and K-ras mutations in patients with completely resected non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients were randomized preoperatively to receive adjuvant postoperative radiotherapy (Arm A) or radiotherapy plus concurrent chemotherapy (Arm B). p53 protein expression was studied by immunohistochemistry (IHC) and p53 mutations in exons 5 to 8 were evaluated by single-strand conformational analysis. K-ras mutations in codons 12, 13, and 61 were determined using engineered restriction fragment length polymorphisms. RESULTS: Four hundred eighty-eight patients were entered onto E3590; 197 tumors were assessable for analysis. Neither presence nor absence of p53 mutations, p53 protein expression, or K-ras mutations correlated with survival or progression-free survival. There was a trend toward improved survival for patients with wildtype K-ras (median, 42 months) compared with survival of patients with mutant K-ras who were randomized to chemotherapy plus radiotherapy (median, 25 months; P = .09). Multivariate analysis revealed only age and tumor stage to be significant prognostic factors, although there was a trend bordering on statistical significance for K-ras (P = .066). Analysis of survival difference by p53 by single-stranded conformational polymorphism and IHC, interaction of p53 and K-ras, interaction of p53 and treatment arm, nodal station, extent of surgery, weight loss, and histology did not reach statistical significance. CONCLUSION: p53 mutations and protein overexpression are not significant prognostic or predictive factors in resected stage II or IIIA NSCLC. K-ras mutations may be a weak prognostic marker. p53 or K-ras should not be routinely used in the clinical management of these patients.

Neuronal nitric-oxide synthase mutant (Ser-1412 --> Asp) demonstrates surprising connections between heme reduction, NO complex formation, and catalysis.

Rat neuronal NO synthase (nNOS) contains an Akt-dependent phosphorylation motif in its reductase domain. We mutated a target residue in that site (Ser-1412 to Asp) to mimic phosphorylation and then characterized the mutant using conventional and stopped-flow spectroscopies. Compared with wild-type, S1412D nNOS catalyzed faster cytochrome c and ferricyanide reduction but displayed slower steady-state NO synthesis with greater uncoupling of NADPH oxidation. Paradoxically, the mutant had faster heme reduction, faster heme-NO complex formation, and greater heme-NO complex accumulation at steady state. To understand how these behaviors related to flavin and heme reduction rates, we utilized three soybean calmodulins (CaMs) that supported a range of slower flavin and heme reduction rates in mutant and wild-type nNOS. Reductase activity and two catalytic parameters (speed and amount of heme-NO complex formation) related directly to the speed of flavin and heme reduction. In contrast, steady-state NO synthesis increased, reached a plateau, and then fell at the highest rate of heme reduction that was obtained with S1412D nNOS + CaM. Substituting with soybean CaM slowed heme reduction and increased steady-state NO synthesis by the mutant. We conclude the following. 1) The S1412D mutation speeds electron transfer out of the reductase domain. 2) Faster heme reduction speeds intrinsic NO synthesis but diminishes NO release in the steady state. 3) Heme reduction displays an optimum regarding NO release during steady state. The unique behavior of S1412D nNOS reveals the importance of heme reduction rate in controlling steady-state activity and suggests that nNOS already has a near-optimal rate of heme reduction.

A kinetic simulation model that describes catalysis and regulation in nitric-oxide synthase.

After initiating NO synthesis a majority of neuronal NO synthase (nNOS) quickly partitions into a ferrous heme-NO complex. This down-regulates activity and increases enzyme K(m,O(2)). To understand this process, we developed a 10-step kinetic model in which the ferric heme-NO enzyme forms as the immediate product of catalysis, and then partitions between NO dissociation versus reduction to a ferrous heme-NO complex. Rate constants used for the model were derived from recent literature or were determined here. Computer simulations of the model precisely described both pre-steady and steady-state features of nNOS catalysis, including NADPH consumption and NO production, buildup of a heme-NO complex, changes between pre-steady and steady-state rates, and the change in enzyme K(m,O(2)) in the presence or absence of NO synthesis. The model also correctly simulated the catalytic features of nNOS mutants W409F and W409Y, which are hyperactive and display less heme-NO complex formation in the steady state. Model simulations showed how the rate of heme reduction influences several features of nNOS catalysis, including populations of NO-bound versus NO-free enzyme in the steady state and the rate of NO synthesis. The simulation predicts that there is an optimum rate of heme reduction that is close to the measured rate in nNOS. Ratio between NADPH consumption and NO synthesis is also predicted to increase with faster heme reduction. Our kinetic model is an accurate and versatile tool for understanding catalytic behavior and will provide new perspectives on NOS regulation.

Comparison of the QTDT analysis for IgE in the CSGA data set.

Over the past few years at least 13 transmission/disequilibrium test (TDT)-based tests have been developed for quantitative (Q) traits for the assessment of association or linkage in the presence of the other. A total of six of these QTDT methods were used to analyze log10IgE in the Collaborative Study on the Genetics of Asthma data set. Only moderate agreement was found between the tests. The results of the QTDT analyses were only slightly affected by the use of gender and age as covariates. Results from analysis of IgE and log10IgE were inconsistent. Our conclusion is that there is only modest agreement among the QTDT methods examined, covariates should be used even if they have a small effect, and that data should be normalized before analysis.

A randomized trial of postoperative adjuvant therapy in patients with completely resected stage II or IIIA non-small-cell lung cancer. Eastern Cooperative Oncology Group.

BACKGROUND: We conducted a randomized trial to determine whether combination chemotherapy plus thoracic radiotherapy is superior to thoracic radiotherapy alone in prolonging survival and preventing local recurrence in patients with completely resected stage II or IIIa non-small-cell lung cancer. METHODS: After surgical staging and resection of the tumor (usually by lobectomy or pneumonectomy), the patients were randomly assigned to receive either four 28-day cycles of cisplatin (60 mg per square meter of body-surface area intravenously on day 1) and etoposide (120 mg per square meter intravenously on days 1, 2, and 3) administered concurrently with radiotherapy (a total of 50.4 Gy, given in 28 daily fractions) or radiotherapy alone (a total of 50.4 Gy, given in 28 daily fractions). RESULTS: Of the 488 patients who were enrolled in the study, 242 were assigned to receive radiotherapy alone and 246 were assigned to receive chemotherapy and radiotherapy. The median duration of follow-up was 44 months. Treatment-associated mortality was 1.2 percent in the group given radiotherapy alone and 1.6 percent in the group given chemotherapy and radiotherapy. The median survival was 39 months in the group given radiotherapy and 38 months in the group given chemotherapy and radiotherapy (P= 0.56 by the log-rank test). The relative likelihood of survival among patients assigned to receive chemotherapy and radiotherapy, as compared with those assigned to receive radiotherapy alone, was 0.93 (95 percent confidence interval, 0.74 to 1.18). Intrathoracic disease recurred within the radiation field in 30 of 234 patients (13 percent) in the group given radiotherapy and in 28 of 236 patients (12 percent) in the group given chemotherapy and radiotherapy (P=0.84); data on recurrence were not available for 18 patients. CONCLUSIONS: As compared with radiotherapy alone, adjuvant radiotherapy and chemotherapy with cisplatin and etoposide does not decrease the risk of intrathoracic recurrence or prolong survival in patients with completely resected stage II or IIIa non-small-cell lung cancer.

Mediastinal lymph node dissection improves survival in patients with stages II and IIIa non-small cell lung cancer. Eastern Cooperative Oncology Group.

BACKGROUND: Mediastinal lymph node dissection (MLND) is an integral part of surgery for non-small cell lung cancer (NSCLC). To compare the impact of systematic sampling (SS) and complete MLND on the identification of mediastinal lymph node metastases and patient survival, the Eastern Cooperative Oncology Group (ECOG) stratified patients by type of MLND before participation in ECOG 3590 (a randomized prospective trial of adjuvant therapy in patients with completely resected stages II and IIIa NSCLC). METHODS: Eligibility requirements for study entry included a thorough investigation of the mediastinal lymph nodes with either SS or complete MLND. The former was defined as removal of at least one lymph node at levels 4, 7, and 10 during a right thoracotomy and at levels 5 and/or 6 and 7 during a left thoracotomy, while the latter required complete removal of all lymph nodes at those levels. RESULTS: Three hundred seventy-three eligible patients were accrued to the study. Among the 187 patients who underwent SS, N1 disease was identified in 40% and N2 disease in 60%. This was not significantly different than the 41% of N1 disease and 59% of N2 disease found among the 186 patients who underwent complete MLND. Among the 222 patients with N2 metastases, multiple levels of N2 disease were documented in 30% of patients who underwent complete MLND and in 12% of patients who had SS (p = 0.001). Median survival was 57.5 months for those patients who had undergone complete MLND and 29.2 months for those patients who had SS (p = 0.004). However, the survival advantage was limited to patients with right lung tumors (66.4 months vs 24.5 months, p<0.001). CONCLUSIONS: In this nonrandomized comparison, SS was as efficacious as complete MLND in staging patients with NSCLC. However, complete MLND identified significantly more levels of N2 disease. Furthermore, complete MLND was associated with improved survival with right NSCLC when compared with SS.

Arginine conversion to nitroxide by tetrahydrobiopterin-free neuronal nitric-oxide synthase. Implications for mechanism.

We studied catalysis by tetrahydrobiopterin (H4B)-free neuronal nitric-oxide synthase (nNOS) to understand how heme and H4B participate in nitric oxide (NO) synthesis. H4B-free nNOS catalyzed Arg oxidation to N(omega)-hydroxy-l-Arg (NOHA) and citrulline in both NADPH- and H(2)O(2)-driven reactions. Citrulline formation was time- and enzyme concentration-dependent but was uncoupled relative to NADPH oxidation, and generated nitrite and nitrate without forming NO. Similar results were observed when NOHA served as substrate. Steady-state and stopped-flow spectroscopy with the H4B-free enzyme revealed that a ferrous heme-NO complex built up after initiating catalysis in both NADPH- and H(2)O(2)-driven reactions, consistent with formation of nitroxyl as an immediate product. This differed from the H4B-replete enzyme, which formed a ferric heme-NO complex as an immediate product that could then release NO. We make the following conclusions. 1) H4B is not essential for Arg oxidation by nNOS, although it helps couple NADPH oxidation to product formation in both steps of NO synthesis. Thus, the NADPH- or H(2)O(2)-driven reactions form common heme-oxy species that can react with substrate in the presence or absence of H4B. 2) The sole essential role of H4B is to enable nNOS to generate NO instead of nitroxyl. On this basis we propose a new unified model for heme-dependent oxygen activation and H4B function in both steps of NO synthesis.