Matching One Sample According to Two Criteria in Observational Studies.

Multivariate matching has two goals: (i) to construct treated and control groups that have similar distributions of observed covariates, and (ii) to produce matched pairs or sets that are homogeneous in a few key covariates. When there are only a few binary covariates, both goals may be achieved by matching exactly for these few covariates. Commonly, however, there are many covariates, so goals (i) and (ii) come apart, and must be achieved by different means. As is also true in a randomized experiment, similar distributions can be achieved for a high-dimensional covariate, but close pairs can be achieved for only a few covariates. We introduce a new polynomial-time method for achieving both goals that substantially generalizes several existing methods; in particular, it can minimize the earthmover distance between two marginal distributions. The method involves minimum cost flow optimization in a network built around a tripartite graph, unlike the usual network built around a bipartite graph. In the tripartite graph, treated subjects appear twice, on the far left and the far right, with controls sandwiched between them, and efforts to balance covariates are represented on the right, while efforts to find close individual pairs are represented on the left. In this way, the two efforts may be pursued simultaneously without conflict. The method is applied to our on-going study in the Medicare population of the relationship between superior nursing and sepsis mortality. The match2C package in R implements the method.

Mortality and cardiovascular disease among older live kidney donors.

Over the past two decades, live kidney donation by older individuals (≥55 years) has become more common. Given the strong associations of older age with cardiovascular disease (CVD), nephrectomy could make older donors vulnerable to death and cardiovascular events. We performed a cohort study among older live kidney donors who were matched to healthy older individuals in the Health and Retirement Study. The primary outcome was mortality ascertained through national death registries. Secondary outcomes ascertained among pairs with Medicare coverage included death or CVD ascertained through Medicare claims data. During the period from 1996 to 2006, there were 5717 older donors in the United States. We matched 3368 donors 1:1 to older healthy nondonors. Among donors and matched pairs, the mean age was 59 years; 41% were male and 7% were black race. In median follow-up of 7.8 years, mortality was not different between donors and matched pairs (p = 0.21). Among donors with Medicare, the combined outcome of death/CVD (p = 0.70) was also not different between donors and nondonors. In summary, carefully selected older kidney donors do not face a higher risk of death or CVD. These findings should be provided to older individuals considering live kidney donation.

Pediatric care for preterm infants after NICU discharge: high number of office visits and prescription medications.

OBJECTIVE: To determine the frequency and risk factors for clinic and pharmacy use in preterm infants during the first year after neonatal intensive care unit (NICU) discharge. STUDY DESIGN: We analyzed clinic visits and prescriptions in a cohort of 23 to 32 weeks infants. We constructed multivariable regression models to determine risk factors for high use. RESULT: The 892 preterm infants experienced 18 346 pediatric visits (mean 20 visits per infant per year) and filled 2100 prescriptions (mean 5.5 prescriptions per year among infants taking medications). Most visits were non-well child care visits to pediatric primary care providers. Prematurity and bronchopulmonary dysplasia (BPD) are important risk factors: infants at 23 to 26 weeks gestation or infants with BPD had an average 29 visits per year and 9 prescriptions per year among infants taking medication. However, half of the highest using infants were relatively healthy infants at 27 to 32 weeks gestation who escaped BPD, NEC or grade 3 to 4 intraventricular hemorrhage. CONCLUSION: Premature infants had frequent pediatric visits and prescription medications. Extreme prematurity and neonatal morbidities are important risk factors; however, half of the highest using infants are moderately preterm without neonatal morbidities.

Safety and immunogenicity of a zoster vaccine in varicella-zoster virus seronegative and low-seropositive healthy adults.

OBJECTIVE: To evaluate immunogenicity and tolerability of a live attenuated zoster vaccine in varicella-zoster virus (VZV) seronegative or low-seropositive adults > or = 30 years of age. STUDY DESIGN: Double-blind, placebo-controlled, randomized, multicenter study. Subjects were enrolled in two stages by prescreened serostatus. Subjects with a low VZV antibody titer (< or = 5 gpELISA units/mL) were enrolled in Stage 1. Subjects with undetecable VZV antibodies and no safety issues identified during Stage 1 were enrolled in Stage 2. All enrolled subjects were randomized 4:1 to receive one dose (approximately 50,000 PFU) of zoster vaccine or placebo and were followed for safety for 42 days postvaccination. Primary objectives/hypotheses: (1) no vaccine-related serious adverse experiences (AE); (2) < or = 1 laboratory-confirmed varicella-like rash with > 50 lesions within 42 days postvaccination. SECONDARY OBJECTIVE: summarize the VZV antibody response postvaccination. RESULTS: Twenty-one subjects (age 27 to 69 years; median 34) enrolled (1148 prescreened); 18 (including 4 seronegative subjects) received vaccine and 3 (including 1 seronegative subject) received placebo. Twenty subjects completed the study; one subject withdrew for reasons unrelated to safety. No serious vaccine-related AE or laboratory-confirmed varicella-like rashes with > 50 lesions were reported. In the zoster vaccine group, all 4 of the initially seronegative subjects (age 32 to 36 years; median 33.5) seroconverted and 6 of the 13 (46.2%) initially seropositive subjects had a > or = 4-fold rise in VZV-specific antibody titer at 6 weeks postvaccination. CONCLUSIONS: The zoster vaccine appears to be immunogenic and generally well tolerated in healthy adults > or = 30 years of age, regardless of initial VZV antibody serostatus.

Notch pathway repression by vestigial is required to promote indirect flight muscle differentiation in Drosophila melanogaster.

Drosophila dorsal longitudinal muscles develop during metamorphosis by fusion of myoblasts with larval templates. It has been shown that both vestigial and Notch are crucial for correct formation of these muscles. We investigated the relationship between vestigial and the Notch pathway during this process. Using Enhancer of Split Region Transcript m6 gene expression as a reporter of Notch pathway activity, we were able to demonstrate that this pathway is only active in myoblasts. Moreover, close examination of the cellular location of several of the main actors of the N pathway (Notch, Delta, neuralized, Serrate, Mind bomb1 and fringe) during dorsal longitudinal muscle development enabled us to find that Notch receptor can play multiple roles in adult myogenesis. We report that the locations of the two Notch ligands (Delta and Serrate) are different. Interestingly, we found that fringe, which encodes a glycosyltransferase that modifies the affinity of the Notch receptor for its ligands, is expressed in muscle fibers and in a subset of myoblasts. In addition, we demonstrate that fringe expression is essential for Notch pathway inhibition and muscle differentiation. Lastly, we report that, in vestigial mutants, fringe expression is lost, and when fringe is overexpressed, a significant rescue of indirect flight muscle degeneration is obtained. Altogether, our data show that a vestigial-differentiating function is achieved through the inhibition of the Notch pathway.

A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults.

BACKGROUND: The incidence and severity of herpes zoster and postherpetic neuralgia increase with age in association with a progressive decline in cell-mediated immunity to varicella-zoster virus (VZV). We tested the hypothesis that vaccination against VZV would decrease the incidence, severity, or both of herpes zoster and postherpetic neuralgia among older adults. METHODS: We enrolled 38,546 adults 60 years of age or older in a randomized, double-blind, placebo-controlled trial of an investigational live attenuated Oka/Merck VZV vaccine ("zoster vaccine"). Herpes zoster was diagnosed according to clinical and laboratory criteria. The pain and discomfort associated with herpes zoster were measured repeatedly for six months. The primary end point was the burden of illness due to herpes zoster, a measure affected by the incidence, severity, and duration of the associated pain and discomfort. The secondary end point was the incidence of postherpetic neuralgia. RESULTS: More than 95 percent of the subjects continued in the study to its completion, with a median of 3.12 years of surveillance for herpes zoster. A total of 957 confirmed cases of herpes zoster (315 among vaccine recipients and 642 among placebo recipients) and 107 cases of postherpetic neuralgia (27 among vaccine recipients and 80 among placebo recipients) were included in the efficacy analysis. The use of the zoster vaccine reduced the burden of illness due to herpes zoster by 61.1 percent (P<0.001), reduced the incidence of postherpetic neuralgia by 66.5 percent (P<0.001), and reduced the incidence of herpes zoster by 51.3 percent (P<0.001). Reactions at the injection site were more frequent among vaccine recipients but were generally mild. CONCLUSIONS: The zoster vaccine markedly reduced morbidity from herpes zoster and postherpetic neuralgia among older adults.

Predicting cisplatin ototoxicity in children: the influence of age and the cumulative dose.

The aim of this study was to determine the risk factors for high-frequency hearing loss in children treated with cisplatin. We scored off-treatment pure-tone audiograms from 153 children (age 6 months to 18 years) who had completed cisplatin therapy (40-200 mg/m(2)/cycle) for germ cell tumours, hepatoblastoma, neuroblastoma or osteosarcoma. The risk of developing bilateral moderate to severe high-frequency hearing loss was significantly related to the age at treatment (P<0.001), and individual and cumulative cisplatin dosages (both P<0.005). Logistic regression showed that children younger than 5 years were at a greater risk of sustaining cisplatin ototoxicity than children older than 15 years, controlling for individual and cumulative doses of cisplatin (Odds Ratio (OR)=21.17, 95% Confidence Interval (CI): 2.48-180.94). Age at treatment and the cumulative dose of cisplatin were the two most important risk factors in predicting moderate to severe high-frequency hearing loss in children treated with cisplatin.

The Drosophila wing differentiation factor vestigial-scalloped is required for cell proliferation and cell survival at the dorso-ventral boundary of the wing imaginal disc.

Links between genes involved in development, proliferation and apoptosis have been difficult to establish. In the Drosophila wing disc, the vestigial (vg) and the scalloped (sd) gene products dimerize to form a functional transcription factor. Ectopic expression of vg in other imaginal discs induces outgrowth and wing tissue specification. We investigated the role of the VG-SD dimer in proliferation and showed that vg antagonizes the effect of dacapo, the cyclin-cdk inhibitor. Moreover, ectopic vg drives cell cycle progression and in HeLa cultured cells, the VG-SD dimer induces cell proliferation per se. In Drosophila, ectopic vg induces expression of dE2F1 and its targets dRNR2 and string. In addition vg, but not dE2F1, interacts with and induces expression of dihydrofolate reductase (DHFR). Moreover, a decrease in VG or addition of aminopterin, a specific DHFR inhibitor, shift the dorso-ventral boundary cells of the disc to a cell death sensitive state that is correlated with reaper induction and DIAP1 downregulation. This indicates that vg in interaction with dE2F1 and DHFR is a critical player for both cell proliferation and cell survival in the presumptive wing margin area.

Control of apterous by vestigial drives indirect flight muscle development in Drosophila.

Drosophila thoracic muscles are comprised of both direct flight muscles (DFMs) and indirect flight muscles (IFMs). The IFMs can be further subdivided into dorsolongitudinal muscles (DLMs) and dorsoventral muscles (DVMs). The correct patterning of each category of muscles requires the coordination of specific executive regulatory programs. DFM development requires key regulatory genes such as cut (ct) and apterous (ap), whereas IFM development requires vestigial (vg). Using a new vg(null) mutant, we report that a total absence of vg leads to DLM degeneration through an apoptotic process and to a total absence of DVMs in the adult. We show that vg and scalloped (sd), the only known VG transcriptional coactivator, are coexpressed during IFM development. Moreover, we observed an ectopic expression of ct and ap, two markers of DFM development, in developing IFMs of vg(null) pupae. In addition, in vg(null) adult flies, degenerating DLMs express twist (twi) ectopically. We provide evidence that ap ectopic expression can induce per se ectopic twi expression and muscle degeneration. All these data seem to indicate that, in the absence of vg, the IFM developmental program switches into the DFM developmental program. Moreover, we were able to rescue the muscle phenotype of vg(null) flies by using the activity of ap promoter to drive VG expression. Thus, vg appears to be a key regulatory gene of IFM development.

A Drosophila model to study the functions of TWIST orthologs in apoptosis and proliferation.

The twist gene has been characterized for its role in myogenesis in several species. In addition, in mammalian cultured cells, it has been shown that twist is a potential oncogene antagonizing p53-dependent apoptosis. To study, in vivo, the role of twist in apoptosis and proliferation, we constructed transgenic Drosophila lines allowing ectopic expression of different twist orthologs. We report that: (i) Drosophila twist induces apoptosis and activates the reaper promoter, (ii) nematode twist induces arrest of proliferation without apoptosis, and (iii) human twist retains its potentialities observed in mammalian cultured cells and antagonizes Drosophila p53-dependent apoptosis. In addition, we show that human twist is able to induce cell proliferation in Drosophila. Data suggest that the pathway by which human twist antagonizes Drosophila p53 could be conserved. These transgenic lines thus constitute a powerful tool to identify targets and modifiers of human twist.

IL-4 receptors on human medulloblastoma tumours serve as a sensitive target for a circular permuted IL-4-Pseudomonas exotoxin fusion protein.

Cytotoxins directed to interleukin-4 receptors have shown to mediate relatively selective cytotoxicity against a variety of human cancer cells in vitro and in vivo. In an ongoing Phase I clinical trial, a recombinant protein comprised of circularly permuted IL-4 fused to a mutated form of Pseudomonas exotoxin (the fusion protein termed IL-4(38-37)-PE38KDEL or cpIL4-PE) has shown antitumour activity against malignant glioma. Human medulloblastomas are neuroectodermal tumours that occur in children and have a poor prognosis. The goal of this study was to determine whether human medulloblastoma derived cell lines express interleukin-4 receptor and whether interleukin-4 receptor expression is accompanied by sensitivity to cpIL4-PE. Medulloblastoma cell lines express interleukin-4 receptor at the protein and mRNA levels as determined by binding, indirect immunofluorescence and RT--PCR studies. These cells expressed IL-4Ralpha (also known as IL-4Rbeta) and IL-13Ralpha1 (also known as IL-13Ralpha') chains, however common gamma(c), a component of the interleukin-4 receptor system in immune cells was not detected. Consistent with the expression of IL-4R, cpIL4-PE was found to be highly and specifically cytotoxic to four of five medulloblastoma cell lines. Susceptibility of medulloblastoma cell lines to cpIL4-PE seemed to correlate closely to the functional IL-4 binding sites in general as demonstrated by 125I-IL-4 binding, but did not seem to correlate with mRNA or cell surface immunoreactive receptor protein expression. The sensitivity of medulloblastoma cells to cpIL4-PE could be eliminated by concurrent incubation with IL-4 or IL-13, but not with IL-2. None of these cell lines showed any change in proliferation upon treatment with exogenous IL-4. These studies establish the interleukin-4 receptor as a medulloblastoma-associated target for possible tumour-directed cancer therapy. Further studies are warranted to investigate interleukin-4 receptor expression in primary medulloblastoma tumours and sensitivity to cpIL-4PE in vitro and in vivo.

Apurinic/apyrimidinic endonuclease activity is elevated in human adult gliomas.

Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair activity that confers resistance to ionizing radiation and alkylating agents in human cell lines. The major Ap endo in human cells is Ape1, an abundant multi-functional protein also known as Ref-1, Hap-1, and Apex. In this work, we assayed Ap endo activity in human adult gliomas to establish correlates with tumor characteristics, and in histologically normal brain adjacent to tumors to characterize changes in activity accompanying neurocarcinogenesis. To our knowledge, this is the first available analysis of Ap endo activity in human brain tumors. Mean activity in 84 gliomas of different diagnostic types and grades was 0.072 +/- 0.095 fmol abasic sites incised/cell/min, ranging approximately 550-fold from 0.00077 to 0.42. The mean for high-grade gliomas was 3.5-fold greater than for low-grade tumors (P < or = 4.0 x 10(-5)), a difference observed within all diagnostic types. Activity was correlated with the fraction of S-phase cells in diploid gliomas (P < or = 0.02), suggesting that proliferation could be a determinant of activity in these tumors. Activity was also correlated with S-phase fraction in the majority of aneuploid gliomas (P < or = 0.03). Moreover, within the aneuploid tumors, there was a significant relationship between activity and the fraction of aneuploid cells (P < or = 4.0 x 10(-4)). In the 58 cases analyzed, mean activity was 7.3-fold higher in gliomas than in adjacent histologically normal brain (0.070 +/- 0.10 versus 0.0096 +/- 0.012 fmol/cell/min; P < or = 3.0 x 10(-5)). Increased tumor activity was observed in 93% of tumor/normal pairs, indicating that elevation of Ap endo activity is characteristic of human gliomagenesis. The elevation was large within most pairs, being 13-fold on average and > or = 10-fold in 43% of cases. A concomitant increase in Ape1 protein was observed by Western blotting in the subset of tumor/normal pairs examined. A clinically important consequence of the increase in Ap endo activity that accompanies neurocarcinogenesis may be enhanced resistance to the radiotherapy and alkylating agent-based chemotherapy that are mainstays of adjuvant therapy for malignant gliomas.

Design and baseline characteristics for the ACE Inhibitor After Anthracycline (AAA) study of cardiac dysfunction in long-term pediatric cancer survivors.

PURPOSE: The ACE Inhibitor After Anthracycline (AAA) study is a randomized, double-blind, controlled clinical trial comparing enalapril with placebo to determine whether treatment can slow the progression of cardiac decline in patients who screen positive for anthracycline cardiotoxicity. METHODS: The primary outcome measure is the rate of decline, over time, in maximal cardiac index (in liters per minute per meters squared) at peak exercise; the secondary outcome measure is the rate of increase in left ventricular end systolic wall stress (in grams per centimeters squared). Patients >2 years off therapy and <4 years from diagnosis, aged 8 years and older, were eligible if they had received anthracyclines and had at least one cardiac abnormality identified at any time after anthracycline exposure. RESULTS: A total of 135 patients were randomized to enalapril or placebo. Baseline characteristics were similar across treatment groups. CONCLUSIONS: The AAA study will provide important information concerning the efficacy of using angiotensin-converting enzyme inhibitors to offset the effects of late anthracycline cardiotoxicity.

Multivariate matching and bias reduction in the surgical outcomes study.

BACKGROUND: Outcomes studies often need a level of detail that is not present in administrative data, therefore requiring abstraction of medical charts. Case-control methods may be used to improve statistical power and reduce abstraction costs, but limitations of exact matching often preclude the use of many covariates. Unlike exact matching, multivariate matching may allow cases to be matched simultaneously on hundreds of covariates. OBJECTIVES: To develop multivariate matched case-control pairs in a study of death after surgery in the Medicare population. RESEARCH DESIGN: Using 830 randomly selected index cases of patients who died within 60 days from admission, controls were found who did not die within that time period, matching on risk for death and other patient characteristics with up to 173 variables used simultaneously in the matching algorithms. SUBJECTS: General and orthopedic Medicare surgical cases in Pennsylvania from 1995 to 1996. Controls were either selected from across the entire state (108,765 possible subjects), or from within the same hospital as the case. MEASURES: Percent bias reduction and the average difference between cases and controls in units of standard deviations. RESULTS: Matched controls were far more similar to cases (deaths) upon admission to the hospital than typical patients, both in statewide and within hospital matches. Bias reduction was usually greater than 50% and often approached 100%. The difference between cases and matched controls for most variables was usually below 0.2 SD. CONCLUSIONS: Multivariate matching methods may aid in conducting studies with Medicare claims records by improving the quality of matches, thereby achieving a better understanding of the etiology of outcomes.

Analysis of the cause, classification, and associated injuries of 166 consecutive pediatric pelvic fractures.

SUMMARY: Pediatric pelvic fractures are serious injuries. Anatomical differences exist between pediatric and adult populations, leading to different causes and rates of death, fracture patterns, and associated injuries. This study is the largest consecutive series of pediatric pelvic fractures from one institution emphasizing the unique aspects seen in pediatrics. One hundred sixty-six children were included. Plain radiography and computed tomography scans were used to classify pelvic fractures. Multisystem injuries occurred in 60%, and 50% sustained additional skeletal injuries. The death rate was 3.6%. Head and/or visceral injuries were the causes of all deaths. Life-threatening hemorrhage did not occur. Urethral injury was not seen as often as in adults. Anterior ring fractures were the most common type, dominated by pedestrian versus motor vehicle trauma. Anatomical differences and mechanism of injury may play a role in these contrasting findings.

Hydrogen bonding and dipolar interactions between quinolines and organic solvents. Nuclear magnetic resonance and ultraviolet-visible spectroscopic studies.

Solvatochromic studies on quinoline (Q), 3-cyanoquinoline (CNQ), 3-bromoquinoline (BrQ) and 8-hydroxyquinoline (OHQ) in pure solvents and alcohol-cyclohexane mixtures have been performed. The results are compared with Proton Nuclear Magnetic Resonance, 1H NMR. studies and AMI calculations. Taft and Kamlet's solvatochromic comparison method was used to disclose solvent effects in pure solvents. These studies shows that the hydrogen bond acceptor ability of the Q ring is diminished and its polarity is increased by the presence of the cyano group in CNQ and the bromo group in BrQ. In OHQ, intramolecular hydrogen bonding has been observed. This interaction is weakened by the interaction with protic solvents. The studies in binary mixtures, alcohol-cyclohexane, show solute-solvent interactions, which compete with solvent self-association in the preferential solvation phenomena. Alcohols with strong ability to self-associate have less preference toward solvation of these compounds. The association constants for solute-ethanol systems were determined by 1H NMR. The results show that the solvent hydrogen bond donor ability is the main factor involved in the interaction with these solutes at the aza aromatic site.

Photodynamic studies of metallo 5,10,15,20-tetrakis(4-methoxyphenyl) porphyrin: photochemical characterization and biological consequences in a human carcinoma cell line.

The photodynamic activities of the free-base 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (TMP) and their metal complexes with zinc(II) (ZnTMP), copper(II) (CuTMP) and cadmium(II) (CdTMP) have been compared in two systems: reverse micelle of n-heptane/sodium bis(2-ethylhexyl)sulfosuccinate/water bearing photooxidizable substrates and Hep-2 human larynx carcinoma cell line. The quantum yields of singlet molecular oxygen, O2(1 delta g), production (phi delta) of TMP, ZnTMP and CdTMP in tetrahydrofuran, were determined yielding values of 0.65, 0.73 and 0.73, respectively, while O2(1 delta g) formation was not detected for CuTMP. In the reverse micellar system, the amino acid L-tryptophan (Trp) was used as biological substrate to analyze the O2(1 delta g)-mediated photooxidation. The observed rate constants for Trp photooxidation (kobsTrp) were proportional to the sensitizer quantum yield of O2(1 delta g). A value of approximately 2 x 10(7) s-1 M-1 was found for the second-order rate constant of Trp (krTry) in this system. The response of Hep-2 cells to cytotoxicity photoinduced by these agents in a biological medium was studied. The Hep-2 cultures were treated with 1 microM of porphyrin for 24 h at 37 degrees C and the cells exposed to visible light. The cell survival at different light exposure levels was dependent on phi delta. Under these conditions, the cytotoxic effect increases in the order: Cu-TMP << TMP < ZnTMP approximately CdTMP, correlating with the production of O2(1 delta g). A similar behavior was observed in both the chemical and biological media indicating that the O2(1 delta g) mediation appears to be mainly responsible for the cell inactivation.