Showing papers by "Pennsylvania State University published in 1996"
5,982 citations
3,152 citations
TL;DR: An integrative conceptual model of child development is presented, anchored within social stratification theory, emphasizing the importance of racism, prejudice, discrimination, oppression, and segregation on the development of minority children and families.
Abstract: In this article a conceptual model for the study of child development in minority populations in the United States is proposed. In support of the proposed model, this article includes (a) a delineation and critical analysis of mainstream theoretical frameworks in relation to their attention and applicability to the understanding of developmental processes in children of color and of issues at the intersection of social class, culture, ethnicity, and race, and (b) a description and evaluation of the conceptual frameworks that have guided the extant literature on minority children and families. Based on the above considerations, an integrative conceptual model of child development is presented, anchored within social stratification theory, emphasizing the importance of racism, prejudice, discrimination, oppression, and segregation on the development of minority children and families.
2,333 citations
TL;DR: In this article, the authors examined two alternative views of the human resources-performance relationship in manufacturing settings and found that human capital enhancement was directly related to multiple dimensions of operational performance (i.e., employee productivity, machine efficiency, and customer alignment).
Abstract: This study examines two alternative views—universal and contingency—of the human resources (HR)-performance relationship in manufacturing settings. Results from a survey of 97 plants primarily support a contingency approach to human resource management (HRM). An HR system focused on human capital enhancement was directly related to multiple dimensions of operational performance (i.e., employee productivity, machine efficiency, and customer alignment), but subsequent analysis revealed that this main effect was predominately the result of linking human-capital-enhancing HR systems with a quality manufacturing strategy. Other manufacturing strategies also moderated the HR-performance relationship.
2,304 citations
TL;DR: Prior applications of structural equation modeling in four major marketing journals between 1977 and 1994 are reviewed and problem areas are identified and avenues for improvement are suggested.
1,999 citations
TL;DR: In this paper, the authors study industry-level patterns in takeover and restructuring activity during the 1982-1989 period and find significant differences in both the rate and time-series clustering of these activities across 51 industries.
1,571 citations
TL;DR: To the knowledge, STM is the first gene shown to mark a specific pattern element in the developing plant embryo both phenotypically and molecularly.
Abstract: The KNOTTED class of plant genes encodes homeodomain proteins. These genes have been found in all plant species where they have been sought and, where examined, show expression patterns that suggest they play an important role in shoot meristem function. Until now, all mutant phenotypes associated with these genes have been due to gain-of-function mutations, making it difficult to deduce their wild-type function. Here we present evidence that the Arabidopsis SHOOT-MERISTEMLESS (STM) gene, required for shoot apical meristem formation during embryogenesis, encodes a class I KNOTTED-like protein. We also describe the expression pattern of this gene in the wild-type plant. To our knowledge, STM is the first gene shown to mark a specific pattern element in the developing plant embryo both phenotypically and molecularly.
1,453 citations
TL;DR: In this paper, the stability of a quantum superposition of two different stationary mass distributions is examined, where the perturbing effect of each distribution on the space-time structure is taken into account, in accordance with the principles of general relativity.
Abstract: The stability of a quantum superposition of two different stationary mass distributions is examined, where the perturbing effect of each distribution on the space-time structure is taken into account, in accordance with the principles of general relativity. It is argued that the definition of the time-translation operator for the superposed space-times involves an inherent ill-definedness, leading to an essential uncertainty in the energy of the superposed state which, in the Newtonian limit, is proportional to the gravitational self-energyEΔ of the difference between the two mass distributions. This is consistent with a suggested finite lifetime of the order of ħ/EΔ for the superposed state, in agreement with a certain proposal made by the author for a gravitationally induced spontaneous quantum state reduction, and with closely related earlier suggestions by Diosi and by Ghirardiet al.
1,278 citations
TL;DR: In this paper, a comprehensive investigation of the thermo-dynamic stability of binary oxides in contact with silicon at 1000 K was conducted, including those involving ternary phases.
Abstract: Using tabulated thermodynamic data, a comprehensive investigation of the thermo-dynamic stability of binary oxides in contact with silicon at 1000 K was conducted. Reactions between silicon and each binary oxide at 1000 K, including those involving ternary phases, were considered. Sufficient data exist to conclude that all binary oxides except the following are thermodynamically unstable in contact with silicon at 1000 K: Li2O, most of the alkaline earth oxides (BeO, MgO, CaO, and SrO), the column IIIB oxides (Sc2O3, Y2O3, and Re2O3, where Re is a rare earth), ThO2, UO2, ZrO2, HfO2, and Al2O3. Of these remaining oxides, sufficient data exist to conclude that BeO, MgO, and ZrO2 are thermodynamically stable in contact with silicon at 1000 K. Our results are consistent with reported investigations of silicon/binary oxide interfaces and identify candidate materials for future investigations.
1,276 citations
TL;DR: The results show that in both the IAM and SMM CAVALLI-SFORZA and EDWARDS' chord distance (DC) and NEI et al.'s DA distance generally show higher PC values than other distance measures, whether the bottleneck effect exists or not.
Abstract: Recently many investigators have used microsatellite DNA loci for studying the evolutionary relationships of closely related populations or species, and some authors proposed new genetic distance measures for this purpose. However, the efficiencies of these distance measures in obtaining the correct tree topology remains unclear. We therefore investigated the probability of obtaining the correct topology (PC) for these new distances as well as traditional distance measures by using computer simulation. We used both the infinite-allele model (IAM) and the stepwise mutation model (SMM), which seem to be appropriate for classical markers and microsatellite loci, respectively. The results show that in both the IAM and SMM CAVALLI-SFORZA and EDWARDS’ chord distance (Dc) and NEI et al.’s DA distance generally show higher PC values than other distance measures, whether the bottleneck effect exists or not. For estimating evolutionary times, however, NEI’S standard distance and GOLDSTEIN et aL’s (6~)‘ are more appropriate than other distances. Microsatellite DNA seems to be very useful for clarifymg the evolutionary relationships of closely related populations.
1,215 citations
TL;DR: In this article, the authors argue that goal orientation is a two-dimensional construct that has both dispostional and situational components and provide a foundation for future organizational research in this area.
TL;DR: In this paper, the authors inserted conjugated molecules, which were 4,4′-di(phenylene-ethynylene)benzenethiolate derivatives, formed single molecular wires that extended from the Au{111} substrate to about 7 angstroms above.
Abstract: Molecular wire candidates inserted into “nonconducting” n -dodecanethiol self-assembled monolayers on Au{111} were probed by scanning tunneling microscopy (STM) and microwave frequency alternating current STM at high tunnel junction impedance (100 gigohms) to assess their electrical properties. The inserted conjugated molecules, which were 4,4′-di(phenylene-ethynylene)benzenethiolate derivatives, formed single molecular wires that extended from the Au{111} substrate to about 7 angstroms above and had very high conductivity as compared with that of the alkanethiolate.
TL;DR: In this article, the authors determine market orientation's relative impact on small-business performance, compared to other influences, in an integrated model using longitudinal data, and find that strong and consistent influences of market orientation on various measures of small-firm performance.
Abstract: The purpose of this article is to determine market orientation’s relative impact on small-business performance, compared to other influences, in an integrated model using longitudinal data. Contrary to expectations based on the management literature, the results indicate weak causal relationships between market environment, small-firm structure, and small-firm strategy. The results further indicate weak influences of these variables, but strong and consistent influences of market orientation, on various measures of small-firm performance. Contrary to expectations based on business policy literature, relative product quality and new product success were not significant influences on profitability, perhaps due to the significant influence of market orientation on these variables. In addition, although increases in growth/share had a significant short-term influence on increases in profitability, high levels of previous years’ firm growth/share had a negative influence on current profitability. The previous year’s level of firm coordinating systems and market competitive intensity has a significant impact on the level of small-firm market orientation.
TL;DR: The authors found that first-generation students differ from their traditional peers in both entering characteristics and college experiences in both reading, math, and critical thinking skills, and that traditional students make greater net gains in reading during their first year.
Abstract: This study sought answers to three questions: (1) Do the precollege characteristics of first-generation students differ from those of traditional students? (2) Do first-generation students' college experiences differ from those of other students? (3) What are the educational consequences of any differences on first-year gains in students' reading, math, and critical thinking abilities? Answers come from 2,685 students (825 first-generation and 1,860 traditional students) who entered 23 diverse institutions nationwide in Fall 1992 and who completed one year of study. First-generation students differ from their traditional peers in both entering characteristics and college experiences. Although traditional students make greater net gains in reading during their first year, the two groups gain to about the same degree in math and critical thinking skills. Those gains, however, appear to result from somewhat different experiences.
TL;DR: The results imply that mutations of genes on chromosome 6 are among those late genetic changes responsible for metastatic potential of malignant melanoma cells and suggest that KiSS-1 expression may be a useful marker for distinguishing metastatic melanoma from nonmetastatic melanomas.
Abstract: Background Microcell-mediated transfer of chromosome 6 into human C8161 and MelJuSo melanoma cell suppresses their ability to metastasize by at least 95% without affecting their tumorigenicity. This observation demonstrates that the ability to metastasize is a phenotype distinct from tumor formation and suggests that tumorigenic cells acquire metastatic capability only after accumulating additional genetic defects. These results also imply that mutations of genes on chromosome 6 are among those late genetic changes responsible for metastatic potential. They further suggest that a melanoma metastasis-suppressor gene(s) is encoded on chromosome 6 or is regulated by genes on chromosome 6. Purpose Our objective was to identify the gene(s) responsible for the suppression of metastasis in chromosome 6/melanoma cell hybrids. Methods A modified subtractive hybridization technique was used to compare the expression of messenger RNAs (mRNAs), via an analysis of complementary DNAs (cDNAs), in metastatic cells (C8161 or MelJuSo) and nonmetastatic hybrid clones (neo6/C8161 or neo6/MelJuSo). Results A novel cDNA, designated KiSS-1, was isolated from malignant melanoma cells that had been suppressed for metastatic potential by the introduction of human chromosome 6. Northern blot analyses comparing mRNAs from a panel of human melanoma cells revealed that KiSS-1 mRNA expression occurred only in nonmetastatic melanoma cells. Expression of this mRNA in normal heart, brain, liver, lung, and skeletal muscle was undetectable by northern blot analysis. Weak expression was found in the kidney and pancreas, but the highest expression was observed in the placenta. The KiSS-1 cDNA encodes a predominantly hydrophilic, 164 amino acid protein with a polyproline-rich domain indicative of an SH3 ligand (binds to the homology 3 domain of the oncoprotein Src) and a putative protein kinase C-alpha phosphorylation site. Transfection of a full-length KiSS-1 cDNA into C8161 melanoma cells suppressed metastasis in an expression-dependent manner. Conclusions These data strongly suggest that KiSS-1 expression may suppress the metastatic potential of malignant melanoma cells. Implications KiSS-1 may be a useful marker for distinguishing metastatic melanomas from nonmetastatic melanomas.
TL;DR: In this paper, a survey was made of framboid size distributions in recently deposited sediments from euxinic (Black Sea; Framvaren Fjord, Norway; Pettaquamscutt River Estuary, Rhode Island, USA), dysoxic (Peru Margin), and oxic (Wallops Island, Virginia, USA; Great Salt Marsh, Delaware, USA) environments.
TL;DR: It is suggested that GAD and its cardinal feature (worry), are associated with lower cardiac vagal control.
TL;DR: In this article, two new methods are proposed for linear regression analysis for data with measurement errors, which are designed to accommodate intrinsic scatter in addition to measurement errors and other lines such as the bisector and orthogonal regression can be constructed.
Abstract: Two new methods are proposed for linear regression analysis for data with measurement errors. Both methods are designed to accommodate intrinsic scatter in addition to measurement errors. The first (BCES) is a direct extension of the ordinary least squares (OLS) estimator to allow for measurement errors. It is quite general, allowing a) for measurement errors on both variables, b) the measurement errors for the two variables to be dependent, c) the magnitudes of the measurement errors to depend on the measurements, and d) other `symmetric' lines such as the bisector and the orthogonal regression can be constructed. The second method is a weighted least squares (WLS) estimator, which applies only in the case where the `independent' variable is measured without error and the magnitudes of the measurement errors on the 'dependent' variable are independent from the measurements. Several applications are made to extragalactic astronomy: The BCES method, when applied to data describing the color-luminosity relations for field galaxies, yields significantly different slopes than OLS and other estimators used in the literature. Simulations with artificial data sets are used to evaluate the small sample performance of the estimators. Unsurprisingly, the least-biased results are obtained when color is treated as the dependent variable. The Tully-Fisher relation is another example where the BCES method should be used because errors in luminosity and velocity are correlated due to inclination corrections. We also find, via simulations, that the WLS method is by far the best method for the Tolman surface-brightness test, producing the smallest variance in slope by an order of magnitude. Moreover, with WLS it is not necessary to ``reduce'' galaxies to a fiducial surface-brightness, since this model incorporates intrinsic scatter.
TL;DR: In this paper, the first price all-pay auction is used to model rent seeking, where asymmetric equilibria imply higher expected revenues than the symmetric equilibrium, and the high bidder receives the item.
Abstract: In a (first price) all-pay auction, bidders simultaneously submit bids for an item. All players forfeit their bids, and the high bidder receives the item. This auction is widely used in economics to model rent seeking, RD asymmetric equilibria imply higher expected revenues than the symmetric equilibrium.
TL;DR: Evidence is presented that human TAF(II)250 and its homologs in Drosophila and yeast have histone acetyltransferase (HAT) activity in vitro, which suggests that targeted hist one acetylation at specific promoters by TAF (II) 250 may be involved in mechanisms by which TFIID gains access to transcriptionally repressed chromatin.
TL;DR: Primary chronic daily headache can be subdivided into transformed migraine, chronic tension-type headache, hemicrania continua, and new daily persistent headache.
Abstract: Primary chronic daily headache can be subdivided into transformed migraine, chronic tension-type headache, hemicrania continua, and new daily persistent headache. We proposed and tested criteria in 150 consecutive outpatients with chronic daily headache. Based on preliminary analysis, we revised the criteria for transformed migraine. Using the International Headache Society criteria, 43% of the patients could not be classified; using our old criteria, 25% could not be classified; however, using our new criteria, we were able to classify 100%. Seventy-eight percent had transformed migraine, 15.3% had chronic tension-type headache, and 6.7% had other headache disorders.
TL;DR: Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice, and its incidence increases with age and the presence of structural heart disease.
Abstract: Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice. Its incidence increases with age and the presence of structural heart disease. It is a major cause of stroke, especially in the elderly. Although the causes are diverse, hypertension is common. Most patients experience palpitations, but fatigue, dyspnea, and dizziness are not uncommon. Patients with an uncontrolled ventricular response during AF may occasionally develop a tachycardia-induced cardiomyopathy. There are three therapeutic goals to consider for patients with AF: rate control, maintenance of sinus rhythm, and prevention of thromboembolism. The risks and benefits of each treatment must be considered for each patient.
### Restoration and Maintenance of Sinus Rhythm
Several drugs effectively restore and maintain sinus rhythm in patients with AF. To date few data are available to confirm superiority of any particular drug over another for this purpose. Agents such as digitalis, verapamil, diltiazem, and β-adrenergic blockers may be useful during AF to decrease the ventricular response that occurs over the atrioventricular (AV) node, but they rarely terminate AF. Intravenous procainamide is the treatment of choice for patients with Wolff-Parkinson-White syndrome who have a preexcited ventricular response during AF, provided they are hemodynamically stable. Patients who are unstable (eg, those with hypotension or significant heart failure) may require immediate cardioversion. Drugs selected for long-term oral therapy should be given initially in low to moderate doses and titrated upward, depending on effectiveness and side effects. Drug interactions with warfarin and digoxin should be monitored. Proarrhythmia is the most important risk associated with antiarrhythmic drug therapy. Bradyarrhythmias, especially sinus bradycardia, and ventricular tachyarrhythmias, especially torsade de pointes, can occur. Proarrhythmia often occurs during initiation of antiarrhythmic drug treatment. In patients without heart disease who have a normal baseline QT interval, ventricular proarrhythmia is relatively rare, and outpatient initiation of treatment is reasonable. However, patients with structural …
TL;DR: The field of cluster research can trace its origins back to the mid-nineteenth century when early studies of colloids, aerosols, and nucleation phenomena were reported.
Abstract: The field of cluster research can trace its origins back to the mid-nineteenth century when early studies of colloids, aerosols, and nucleation phenomena were reported. The field underwent a resurgence of interest several decades ago when well-defined clusters were observed in supersonic expansions that could be investigated using mass spectrometers. The advent of the laser provided a new dimension, enabling detailed spectroscopic observations through the probing of systems of varying size and degree of solvation. Modern interest derives from recognition that interrogating clusters provides a way of studying the energetics and dynamics of intermediate states of matter as cluster systems evolve from the gas toward the condensed state. Herein, we endeavor to highlight some of the significant advances which have been made during the past several decades that have led to a nearly explosive growth of interest in the field of cluster science. Finally, we conclude that the field will continue to expand through i...
TL;DR: Two of the more fundamental ways in which molecules change their behavior when they are dissolved are that they can begin to exchange energy with the surrounding liquid and they can induce their surroundings to rearrange so as to provide a significant stabilizing influence as mentioned in this paper.
Abstract: Two of the more fundamental ways in which molecules change their behavior when they are dissolved are that they can begin to exchange energy with the surrounding liquid and they can induce their surroundings to rearrange so as to provide a significant stabilizing influence. The first of these is typified by the process of vibrational population relaxation of a vibrationally hot species. The second conceptcritical to solution chemistryis what is known as solvation. Both of these processes are sufficiently fundamental that one would really like to know, at the most mechanical and molecular level possible, just what events are required in order to make them happen. But how difficult is it going to be to extract such molecular detail from the complicated many-body dynamics? The most microscopic level of understanding one could ever hope to possess might seem far removed from the finely detailed dynamical information which is available routinely for individual isolated molecules and for molecule−molecule colli...
TL;DR: The many known phenomena that decrease oligodendrocyte survival and/or myelin production may mediate their effect through a final common pathway that involves disruptions in iron availability or intracellular management of iron.
Abstract: Oligodendrocytes are the predominant iron-containing cells in the brain. Iron-containing oligodendrocytes are found near neuronal cell bodies, along blood vessels, and are particularly abundant within white matter tracts. Iron-positive cells in white matter are present from birth and eventually reside in defined patches of cells in the adult. These patches of iron-containing cells typically have a blood vessel in their center. Ferritin, the iron storage protein, is also expressed early in development in oligodendrocytes in a regional and cellular pattern similar to that seen for iron. Recently, the functionally distinct subunits of ferritin have been analyzed; only heavy (H)-chain ferritin is found in oligodendrocytes early in development. H-ferritin is associated with high iron utilization and low iron storage. Consistent with the expression of H-ferritin is the expression of transferrin receptors (for iron acquisition) on immature oligodendrocytes. Transferrin protein accumulation and mRNA expression in the brain are both dependent on a viable population of oligodendrocytes and may have an autocrine function to assist oligodendrocytes in iron acquisition. Although apparently the majority of oligodendrocytes in white matter tracts contain ferritin, transferrin, and iron, not all of them do, indicating that there is a subset of oligodendrocytes in white matter tracts. The only known function of oligodendrocytes is myelin production, and both a direct and indirect relationship exists between iron acquisition and myelin production. Iron is directly involved in myelin production as a required co-factor for cholesterol and lipid biosynthesis and indirectly because of its requirement for oxidative metabolism (which occurs in oligodendrocytes at a higher rate than other brain cells). Factors (such as cytokines) and conditions such as iron deficiency may reduce iron acquisition by oligodendrocytes and the susceptibility of oligodendrocytes to oxidative injury may be a result of their iron-rich cytoplasm. Thus, the many known phenomena that decrease oligodendrocyte survival and/or myelin production may mediate their effect through a final common pathway that involves disruptions in iron availability or intracellular management of iron.
TL;DR: In this article, the Journal of Retailing published a survey of the state of the art in the field of online retailing, and the definite version is available at: http://doi.sciencedirect.com/science/article/pii/S0022435996900068
TL;DR: In this paper, the authors evaluated the extent to which cohabitation is similar to marriage using data from the 1987-1988 National Survey of Families and Households and found that cohabitors in general report poorer relationship quality than their married counterparts.
Abstract: Using data from the 1987-1988 National Survey of Families and Households, we evaluate the extent to which cohabitation is similar to marriage. The quality of recently formed cohabiting and marital relationships among Black and White Americans ages 19 to 48 is investigated in an effort to advance our understanding of the meaning of cohabitation relative to marriage. Controlling for relationship duration and demographic characteristics of the respondent, we find that cohabitors in general report poorer relationship quality than their married counterparts. However, cohabitors' marriage plans largely explain the difference in relationship quality of cohabitors and marrieds. The majority of cohabitors report plans to marry their partner, and these cohabitors are involved in unions that are not significantly different from marriages. In fact, cohabitors report more frequent interaction with their partners than do marrieds. The relationship quality of marrieds and cohabitors with plans to marry is affected in the same way by the presence of potential sources of stress such as biological children, children from past unions, and prior union experience. Cohabitation is a complex family form. For about half of cohabitors, it is a relationship that lasts approximately 2 years and then ends, either through marriage or dissolution. For others, it is a precursor to marriage. And for one tenth of cohabitors, it is a long-term relationship that seldom ends in marriage (Bumpass & Sweet, 1989). In the majority of cases, cohabitation shares many of the qualities of marriage. It involves sharing a residence and personal resources, excluding intimate relations with others, and, in a substantial number of cases, having a child. More than 10% of cohabitors experience the birth of a child while cohabiting, and about one quarter bring children from previous unions to their current cohabiting relationship (Bumpass, Sweet, & Cherlin, 1991). Despite its similarity to marriage, we know almost nothing about the quality of cohabiting relationships compared with what we know about the quality of marital relations. In this article, we use data from the 1987-1988 National Survey of Families and Households to compare the relationship quality of cohabitors and marrieds and to determine which cohabitors are involved in unions that are qualitatively comparable to marriages. Additional analyses are performed to determine whether moderating variables, such as children and previous union experience, have similar effects on the relationship quality of cohabitors and marrieds. The meaning of cohabitation is of particular relevance today because cohabitation has become an increasingly popular form of living. Whereas just 11% of marriages between 1965 and 1974 were preceded by cohabitation, between 1980 and 1984, 44% of all marriages involved at least one spouse who had cohabited (Bumpass & Sweet, 1989). Nearly 50% of Americans in their 20s and 30s have cohabited (Bumpass et al., 1991). In 1994, there were 3.7 million cohabiting couples in the United States (U.S. Bureau of the Census, 1995). Previous research on cohabitation has focused largely on the effects of premarital cohabitation on subsequent marital stability. Researchers also have debated the meaning of cohabitation relative to marriage and remaining single. Although some researchers (e.g., Bumpass & Sweet, 1989; Bumpass et al., 1991) have argued that cohabitation and marriage are highly similar, others (e.g., Rindfuss & VandenHeuvel, 1990) have argued that cohabitation is more like being single. This article examines the nature of cohabiting and marital relationships and assesses the extent to which the two are similar. Understanding the quality of the relationships in which cohabitors are involved is important not only because of the large and increasing number of people who cohabit, but also because, for a nontrivial proportion of cohabitors, it is a permanent living arrangement, a replacement for marriage. …
TL;DR: The data suggest that both speed and working memory are fundamental to explaining age-related changes in cognitive aging but that the relative contributions of these constructs vary as a function of the type of memory task.
Abstract: An individual-differences approach was used to examine the component processes that predict episodic long-term memory performance A total of 301 participants ages 20-90 received a 7-hr cognitive battery across 3 days Key constructs hypothesized to affect long-term memory function were assessed, including multiple measures of working memory and perceptual speed Latent-construct, structural equation modeling was used to examine the relationship of these measures and age to different types of long-term memory tasks Speed was a key construct for all 3 types of memory tasks, mediating substantial age-related variance; working memory was a fundamental construct for free and cued recall but not spatial memory The data suggest that both speed and working memory are fundamental to explaining age-related changes in cognitive aging but that the relative contributions of these constructs vary as a function of the type of memory task
TL;DR: troglitazone improves total body insulin action in PCOS, resulting in lower circulating insulin levels; 2) insulin resistance, probably via hyperinsulinemia, results in a general augmentation of steroidogenesis and LH release in PCos; and 3) insulin-sensitizing agents, such as trog litazone, may provide a novel therapy for PCOS.
Abstract: We performed this study to investigate the hypothesis that insulin resistance plays a role in the pathogenesis of reproductive abnormalities in women with the polycystic ovary syndrome (PCOS). Twenty-five women with PCOS were enrolled in a double-blind randomized 3-month trial of two doses of the insulin-sensitizing agent, troglitazone, 21 of whom completed the study: 200 mg, n = 10; 400 mg, n = 11. Baseline hormonal parameters and glucose tolerance were compared with 12 age- and weight-matched ovulatory control women. There were no significant changes in body mass index during the study. Fasting (P < 0.01) and 2-h post-75-g glucose load insulin levels (P < 0.05), as well as integrated insulin responses to the glucose load, decreased (P < 0.05), and insulin sensitivity assessed by a frequently sampled iv glucose tolerance test increased significantly (P < 0.001) during troglitazone treatment. This was accompanied by significant decreases in the levels of nonsex hormone-binding globulin-bound testosterone (P < 0.01), dehydroepiandrosterone sulfate (P < 0.001), estradiol (P < 0.01), and estrone (P < 0.001). Stepwise regression analysis indicated that decreases in nonsex hormone-binding globulin testosterone levels were significantly correlated with decreases in integrated insulin responses to the glucose load (r2 0.44, P < 0.01). The only significant changes at the 200-mg troglitazone dose were an increase in insulin sensitivity (P < 0.05) and decreases in dehydro-epiandrosterone sulfate (P < 0.01) and estrone (P < 0.05) levels. At the 400-mg dose, in addition to the changes noted in the entire troglitazone treatment group, increases in the disposition index (the product of insulin sensitivity and secretion) achieved significance, as did decreases in androstenedione (P < 0.01) and LH (P < 0.05) levels and increases in sex hormone-binding globulin levels (P < 0.01). Two PCOS women had ovulatory menses. We conclude that 1) troglitazone improves total body insulin action in PCOS, resulting in lower circulating insulin levels; 2) insulin resistance, probably via hyperinsulinemia, results in a general augmentation of steroidogenesis and LH release in PCOS; and 3) insulin-sensitizing agents, such as troglitazone, may provide a novel therapy for PCOS.