bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal lifestyle factors and risk for ventricular septal defects
Authors: Williams Laura J. , Correa Adolfo , Rasmussen Sonja
Published: February 2004

Background

Several studies have shown that the prevalence of ventricular septal defects (VSDs) has increased significantly in the United States in the past 30 years. This increase has been primarily attributed to increased detection through echocardiography. However, little is known about the etiology of VSD. This study sought to evaluate the association between maternal lifestyle exposures and the risk for VSD in offspring.

METHODS

The Atlanta Birth Defects Case–Control Study was used to identify 122 isolated simple VSD cases and 3029 control infants born during the period 1968 through 1980 in the metropolitan Atlanta area. Exposure data on alcohol, cigarette, and illicit drug use were obtained through standardized interviews with mothers and fathers. Associations between lifestyle factors and VSD were calculated using maternal self‐reports; associations were also calculated using paternal proxy‐reports of the mother's exposures.

RESULTS

Maternal self‐report of heavy alcohol consumption and paternal proxy‐report of the mothers' moderate alcohol consumption were associated with isolated simple VSD. A two‐fold increase in risk of isolated simple VSD was identified for maternal self‐ and paternal proxy‐reported cannabis use. Risk of isolated simple VSD increased with regular (three or more days per week) cannabis use for both maternal self‐ and paternal proxy‐report, although the association was significant only for maternal self‐report.

CONCLUSIONS

This is the first study to identify an association between maternal marijuana use and VSD in offspring. Further studies are needed to elucidate this association. Birth Defects Research (Part A) 67:000–000, 2003. © 2003 Wiley‐Liss, Inc.
2,3,7,8‐tetrachlorodibenzo‐p‐dioxin reduces myocardial hypoxia and vascular endothelial growth factor expression during chick embryo development
Authors: Ivnitski‐Steele Irena D. , Sanchez Andrea , Walker Mary K.
Published: February 2004

BACKGROUND

Previous research has demonstrated that 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) induces cardiomyocyte growth arrest, thinner ventricle walls, and reduced number and size of coronary arteries during chick embryogenesis. Coronary vascular development is believed to be mediated, in part, by myocardial oxygen gradients and a subsequent increase in hypoxia‐inducible factor 1α (HIF‐1α) and vascular endothelial growth factor‐A (VEGF‐A) expression. We investigated whether TCDD inhibition of coronary development was associated with altered myocardial oxygen status and reduced cardiac HIF‐1α and VEGF‐A.

METHODS

Chick embryos were exposed to 15% or 20% O2 for 24 hr from incubation days 9–10 or were injected with control (corn oil) or 0.24 pmol TCDD/gm egg on day 0. On day 9, embryos were injected with control (0.9% NaCl) or EF5, a tissue hypoxia marker, and cardiac binding of EF5 was determined by immunohistochemistry on day 10. In addition, embryo hearts were analyzed for VEGF‐A mRNA by in situ hybridization and quantitative RT‐PCR, and for HIF‐1α mRNA by quantitative RT‐PCR.

RESULTS

Cardiac binding of EF5 was significantly increased in embryos exposed to 15% O2, compared to embryos exposed to 20% O2. In contrast, TCDD‐exposed embryos exhibited significantly reduced binding of EF5 in the heart, compared to controls. Similarly, cardiac expression of HIF‐1α and VEGF‐A were increased following hypoxia and tended to be decreased following TCDD exposure.

CONCLUSIONS

These results suggest that the myocardium may be a target of TCDD toxicity, resulting in reduced myocardial hypoxia, and HIF‐1α and VEGF‐A expression believed necessary for normal coronary development. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Analysis of two translocation breakpoints and identification of a negative regulatory element in patients with Rieger's syndrome
Authors: Trembath Dimitri G. , Semina Elena V. , Jones Douglas H. , Patil Shivanand R. , Qian Qining , Amendt Brad A. , Russo Andrew F. , Murray Jeffrey C.
Published: February 2004

BACKGROUND

Rieger's syndrome is an autosomal dominant disorder characterized by eye, tooth, and umbilical anomalies. A gene responsible for Rieger's syndrome, PITX2, has previously been cloned using two patients with balanced translocations, t(4;16) and t(4;11), with breakpoints that lie near the gene, but which do not interrupt it.

METHODS

We sequenced both breakpoint regions on chromosome 4 and screened this area for novel genes. Fluorescence in situ hybridization (FISH) was used to determine if PITX2 was still present on the 4:16 chromosome. Both the chromosome 16 and chromosome 11 breakpoints were cloned and sequenced using panhandle polymerase chain reaction (PHPCR). Transient transfection studies were performed to compare effects on a reporter gene between native chromosome 4 sequence and chromosome 11 sequence.

RESULTS

The region surrounding PITX2 on chromosome 4 is rich in repetitive elements, but no novel genes were identified. FISH demonstrated that PITX2 was intact on the 4:16 translocation chromosome. The PHPCR experiments demonstrated that the translocated regions of chromosomes 16 and 11 were repeat‐rich, and transfection studies revealed a slight enhancer effect with the chromosome 4 sequence, and a strong silencer effect when the chromosome 11 sequence was present.

CONCLUSIONS

Given the lack of any novel genes near either breakpoint, changes in potential regulatory elements may be the best model to explain the loss of PITX2 expression in these patients and hence the Rieger's syndrome phenotype. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Effects of thalidomide on reproductive function and early embryonic development in male and female New Zealand white rabbits
Authors: Teo Steve K. , Denny Kevin H. , Stirling David I. , Thomas Steve D. , Morseth Sandra L. , Hoberman Alan M.
Published: February 2004

BACKGROUND: The present work was performed to determine the effect of thalidomide exposure on reproductive function and early embryonic development. METHODS: Twenty‐five female New Zealand White rabbits were orally gavaged with 0, 10, 50, or 100 mg/kg/day thalidomide 14 days prior to mating through to gestation day 7 for a total of 22 days. Treated females were Caesarean‐sectioned approximately 29 days after the date of attempted mating. Following mating with treated females, male rabbits (25/dose) were gavaged with 0, 30, 150, or 500 mg/kg/day beginning 14 days prior to mating with a group of untreated females (25/dose). Doses were administered through mating until the day before sacrifice for a minimum of 56 days. Untreated females were Caesarean‐sectioned 29 days after the last attempted mating. Comprehensive necropsy and histopathology of the reproductive system were performed. RESULTS: Treated females had reduction in body weight gain during gestation. Mating and pregnancy parameters were unaffected by thalidomide. At 100 m/kg, litter averages for corpora lutea, implantations, litter sizes, does with viable fetuses and live fetuses decreased and the number of early resorptions, does with any resorptions, does with all conceptuses resorbed, and the percent resorbed conceptuses per litter increased. The number of early resorptions, the average number of early resorptions per litter, and the percent resorbed conceptuses per litter increased at 10 and 50 mg/kg. There were no thalidomide‐related external fetal malformations. Mating and fertility in male rabbits were unaffected by thalidomide. There was an increased incidence of flaccid testes at 150 and 500 mg/kg and of bilateral small testes in all treated groups. At 500 mg/kg, there was degeneration of the germinal epithelium of the testicles with an increase in multinucleated giant cells in seminiferous tubule and a loss of round and elongating spermatids. CONCLUSIONS: Thalidomide had no adverse effects on mating and fertility in male and female rabbits dosed up to 500 and 100 mg/kg/day, respectively, for 14 days prior to mating. After 56 day of dosing, histopathologic changes with no associated sperm abnormalities were observed in the testicles. Embryonic development NOAEL for treated females mated to untreated males was <10 mg/kg. Corresponding fertility NOAEL for treated males mated to untreated females was 500 mg/kg. Birth Defects Res B 71:1–16, 2004. © 2004 Wiley‐Liss, Inc.
Effects of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) on fatty acid availability and neural tube formation in cynomolgus macaque, Macaca fascicularis
Authors: Moran F. M. , Hendrickx A. G. , Shideler S. , Overstreet J. W. , Watkins S. M. , Lasley B. L.
Published: February 2004

2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is known to alter carbohydrate utilization and specific steps in lipid metabolism. TCDD interacts with estradiol in mobilizing specific fatty acids in chickens that may be a cause of cranial/beak malformations in this species. This study was designed to test the hypothesis that TCDD simultaneously alters critical fatty acid mobilization during early pregnancy and determine if those changes correlate to morphological defects of the developing neural tube in the nonhuman primate. Cynomolgus macaques were treated with a single dose of 4 μg/kg body weight (BW) TCDD on gestational day 15 or 20. Pregnancies were terminated by hysterectomy on gestational day 24–26 and embryos were examined to determine morphology of the developing neural tube. Maternal blood samples were used for fatty acid quantification. Embryos exhibited cellular changes, mainly increased cell death, and intercellular spaces in the neural tube, suggestive of an adverse effect on the developing nervous system. Significant decreases on fatty acid composition were found on some of the eight classes of lipids analyzed. Particularly, a decrease was observed in the n‐3 (40–60%) and n‐6 (47–75%) essential fatty acids in treated pregnancies compared to untreated controls. These data demonstrate the effect of TCDD in decreasing maternal levels of n‐3 and n‐6 fatty acids that are considered necessary for normal development in mammals. Since neural tube development is dependent, in part, on n‐3 and n‐6 fatty acids, it is possible that the limitation of these essential fatty acids in plasma resulted in the observed detrimental effects on early brain development. Birth Defects Res B 71:37–46, 2004. © 2004 Wiley‐Liss, Inc.
Amidic modification of valproic acid reduces skeletal teratogenicity in mice
Authors: Okada Akinobu , Kurihara Hiroshi , Aoki Yoshinobu , Bialer Meir , Fujiwara Michio
Published: February 2004

BACKGROUND: The antiepileptic drug valproic acid (VPA) is well known to cause neural tube and skeletal defects in both humans and animals. The amidic VPA analogues valpromide (VPD) and valnoctamide (VCD) have much lower teratogenicity than VPA inducing exencephaly in mice. The objective of this study was to investigate the teratogenic effects of VPA, VPD, and VCD on the skeleton of NMRI mice. METHODS: Pregnant NMRI mice were given a single subcutaneous injection of VPA (400 and 800 mg/kg), VPD (800 mg/kg), or VCD (800 mg/kg) on the morning of gestation day (GD) 8. Cesarean section was carried out on GD 18. Live fetuses were double‐stained for bone and cartilage and their skeletons were examined. RESULTS: Significant increases in fetal loss and exencephaly rate were observed with VPA at 800 mg/kg compared to the vehicle control. There were no significant differences between either VPD or VCD and the control groups for any parameter at cesarean section. A number of abnormalities were dose‐dependently induced at high incidences by VPA in both the cartilage and bone of vertebrae, ribs and sternum. In contrast, lower frequencies of abnormality were exhibited with VPD and VCD than VPA in all skeletons affected by VPA. CONCLUSIONS: These findings clearly indicate that VPD and VCD are distinctly less teratogenic than VPA in the induction of not only neural tube defects, but also skeletal abnormalities. A structure‐teratogenicity relationship of VPA on the skeleton is suspected. Birth Defects Res B 71:47–53, 2004. © 2004 Wiley‐Liss, Inc.
Effects of restraint stress in gestation: Implications for rodent developmental toxicology studies
Authors: Golub Mari S. , Campbell Marlissa A. , Kaufman Farla L. , Iyer Poorni , Li Ling‐Hong , Donald James M. , Morgan James E.
Published: February 2004

Restraint has been used as a procedure to study the effects of stress on gestation outcome in rodents. The effects of restraint could potentially be used as a model for the impact of general stress produced by high doses of toxicants and other interventions. In mice, restraint in the peri‐implantation period leads to implantation failure, and restraint at appropriate times in organogenesis produces cleft palate, supernumerary ribs, and resorption. In rats, there is some evidence for an association with restraint for implantation failure, but not for the morphological anomalies. Restraint in late gestation alters adult sexual behavior of male rat offspring, but consequences for their fertility are not known. Intrauterine growth retardation is not commonly associated with gestational restraint. In the few studies where they have been directly compared, different restraint procedures produced graded, qualitatively different, or no effects. Adrenocortical hormones have been implicated as mediating the effect of restraint on cleft palate, but not on supernumerary ribs, implantation failure, or sexual differentiation. Given the variety of restraint procedures and the varying species‐dependent consequences, it is not possible to infer a generalizable pattern of developmental effects due to gestational stress from the restraint literature. As an alternative approach, contemporary methods in gene expression and developmental biology could profitably be applied to understanding different patterns of stress‐mediated effects of toxicant exposures on intrauterine development. Birth Defects Res B 71:26–36, 2004. © 2004 Wiley‐Liss, Inc.
Why does the species problem still persist?
Authors: Reydon Thomas A.C.
Published: February 2004

Despite many years of discussion, the species problem has still not been adequately resolved. Why is this the case? Here I discuss two recent suggested answers to this question that place the blame on the species problem's empirical aspects or on its philosophical aspects. In contrast, I argue that neither of these two faces of the species problem constitute the principal cause of the species problem's persistence. Rather, they are merely symptoms of the real cause: the species problem has not yet gone away because of a failure to recognize that not one but a number of distinct concepts are at the heart of the problem. To illustrate this point, a recently proposed solution to the problem is examined: the suggestion to understand the concept of species as a family resemblance concept. BioEssays 26:300–305, 2004. © 2004 Wiley Periodicals, Inc.
The polychaete Platynereis dumerilii (Annelida): a laboratory animal with spiralian cleavage, lifelong segment proliferation and a mixed benthic/pelagic life cycle
Authors: Fischer Albrecht , Dorresteijn Adriaan
Published: February 2004

Platynereis dumerilii, a marine polychaetous annelid with indirect development, can be continuously bred in the laboratory. Here, we describe its spectacular reproduction and development and address a number of open research problems. Oogenesis is easily studied because the oocytes grow while floating in the coelom. Unlike the embryos of other model spiralians, the Platynereis embryo is transparent giving insight into the dynamic structures and processes inside the cells that accompany the prevailing anisotropic cleavages. Functional studies on cell specification and differential gene expression in embryos, larvae, and later stages are underway. Lifelong proliferation of uniform trunk segments qualifies Platynereis as a model for the study of gene expression and of the functional circuitry of this process. Platynereis can also become a stepping stone in the comparison of segmentation between annelids and arthropods because it comes closer to the putative ancestral morphology and style of development than other model annelids. BioEssays 26:314–325, 2004. © 2004 Wiley Periodicals, Inc.
Werner syndrome protein, the MRE11 complex and ATR: menage‐à‐trois in guarding genome stability during DNA replication?
Authors: Pichierri Pietro , Franchitto Annapaola
Published: February 2004

The correct execution of the DNA replication process is crucially import for the maintenance of genome integrity of the cell. Several types of sources, both endogenous and exogenous, can give rise to DNA damage leading to the DNA replication fork arrest. The processes by which replication blockage is sensed by checkpoint sensors and how the pathway leading to resolution of stalled forks is activated are still not completely understood. However, recent emerging evidence suggests that one candidate for a sensor of replication stress is ATR and that, together with a member of RecQ family helicases, Werner syndrome protein (WRN) and MRE11 complex, can collaborate to promote the restarting of DNA synthesis through the resolution of stalled replication forks. Here, we discuss how WRN, the MRE11 complex and the ATR kinase could work together in response to replication blockage to avoid DNA replication fork collapse and genome instability. BioEssays 26:306–313, 2004. © 2004 Wiley Periodicals, Inc.
Problems of somatic mutation and cancer
Authors: Frank Steven A. , Nowak Martin A.
Published: February 2004

Somatic mutation plays a key role in transforming normal cells into cancerous cells. The analysis of cancer progression therefore requires the study of how point mutations and chromosomal mutations accumulate in cellular lineages. The spread of somatic mutations depends on the mutation rate, the number of cell divisions in the history of a cellular lineage, and the nature of competition between different cellular lineages. We consider how various aspects of tissue architecture and cellular competition affect the pace of mutation accumulation. We also discuss the rise and fall of somatic mutation rates during cancer progression. BioEssays 26:291–299, 2004. © 2004 Wiley Periodicals, Inc.
Hypoxia‐inducible factor‐1 and oncogenic signalling
Authors: Bárdos Julia I. , Ashcroft Margaret
Published: February 2004

An understanding of underlying mechanisms involved in the activation of HIF‐1 in response to both hypoxic stress and oncogenic signals has important implications for how these processes may become deregulated in human cancer. Changes in microenvironmental stimuli such as hypoxia and growth factors in combination with genetic lesions, such as loss or inactivation of p53, PTEN or pVHL or oncogenic activation, can all lead to increased HIF‐1 activity. This provides cancer cells with a distinct advantage for survival and proliferation, resulting in their ability to form vascular tumours, which are aggressive and metastatic. Accordingly, upregulation of HIF‐1α, a key component of HIF‐1, correlates with a poor treatment outcome using conventional therapies. A variety of mechanisms exist that regulate expression of HIF‐1α. In recent years, it has become clear that an extensive network of signalling cascades converge on HIF‐1α to regulate the transcriptional response. A better understanding of this regulation may provide a basis for the development of new cancer therapies. BioEssays 26:262–269, 2004. © 2004 Wiley Periodicals, Inc.
Is sperm capacitation analogous to early phases of Ca2+‐triggered membrane fusion in somatic cells and viruses?
Authors: Tulsiani Daulat R.P. , Abou‐Haila Aïda
Published: February 2004

An important feature of male fertility is the physiological priming of spermatozoa by a multifaceted process collectively referred to as capacitation. The end point of this evasive process is the hyperactivated spermatozoa capable of binding to terminal sugar residues on the egg's extracellular coat, the zona pellucida (ZP), and undergoing acrosomal exocytosis (i.e., induction of the acrosome reaction). The hydrolytic action of acrosomal enzymes released at the site of zona binding, along with the enhanced thrust generated by the hyperactivated beat pattern of the bound spermatozoa, are important factors that regulate the penetration of ZP and fertilization of the egg. Despite many advances in identifying sperm components that promote capacitation, the mechanism underlying the calcium‐triggered process remains elusive. The purpose of this review article is to focus on new advances that have enhanced our understanding of in vivo/in vitro capacitation, a prerequisite event resulting from a dramatic modification and reorganization of the sperm membrane molecules. Special emphasis has been laid on accumulating evidence suggesting potential similarities between the sperm capacitation and early phases of calcium‐triggered membrane fusion (i.e., tethering and docking) during secretory and endocytotic pathways among eukaryotes. BioEssays 26:281–290, 2004. © 2004 Wiley Periodicals, Inc.
Carbon monoxide in biology and medicine
Authors: Ryter Stefan W. , Otterbein Leo E.
Published: February 2004

Carbon monoxide (CO), a product of organic oxidation processes, arises in vivo during cellular metabolism, most notably heme degradation. CO binds to the heme iron of most hemoproteins. Tissue hypoxia following hemoglobin saturation represents a principle cause of CO‐induced mortality in higher organisms, though cellular targets cannot be excluded. Despite extreme toxicity at high concentrations, low concentrations of CO can confer cytoprotection during ischemia/reperfusion or inflammation‐induced tissue injury. Likewise, heme oxygenase, an enzyme that produces CO, biliverdin and iron, as well as a secondary increase in ferritin synthesis, from the oxidation of heme, can confer protection in vivo and in vitro. CO has been shown to affect several intracellular signaling pathways, including guanylate cyclase, which generates guanosine 3′:5′ cyclic monophosphate and the mitogen‐activated protein kinases (MAPK). Such pathways mediate, in part, the known vasoregulatory, anti‐inflammatory, anti‐apoptotic and anti‐proliferative effects of this gas. Exogenous CO delivered at low concentrations is showing therapeutic potential as an anti‐inflammatory agent and as such can modulate numerous pathophysiological states. This review will delve into the biological significance and medical applications of this gas molecule. BioEssays 26:270–280, 2004. © 2004 Wiley Periodicals, Inc.
Making more heart muscle
Authors: van den Hoff Maurice JB , Kruithof Boudewijn PT , Moorman Antoon FM
Published: February 2004

Postnatally, heart muscle cells almost completely lose their ability to divide, which makes their loss after trauma irreversible. Potential repair by cell grafting or mobilizing endogenous cells is of particular interest for possible treatments for heart disease, where the poor capacity for cardiomyocyte proliferation probably contributes to the irreversibility of heart failure. Knowledge of the molecular mechanisms that underly formation of heart muscle cells might provide opportunities to repair the diseased heart by induction of (trans) differentiation of endogenous or exogenous cells into heart muscle cells. We briefly review the molecular mechanisms involved in early development of the linear heart tube by differentiation of mesodermal cells into heart muscle cells. Because the initial heart tube does not comprise all the cardiac compartments present in the adult heart, heart muscle cells are added to the distal borders of the tube and within the tube. At both distal borders, mesodermal cell are recruited into the cardiac lineage and, within the heart tube, muscular septa are formed. In this review, the relative late additions of heart muscle cells to the linear heart tube are described and the potential underlying molecular mechanisms are discussed. BioEssays 26:248–261, 2004. Wiley Periodicals, Inc.
Rac1 and Rac2 GTPases in haematopoiesis
Authors: Weston Victoria J. , Stankovic Tatjana
Published: February 2004

The highly homologous Rac1 and Rac2 GTPases are co‐expressed in cells of haematopoietic origin and are likely to show some functional redundancy. While disruption of the Rac2 gene in mice has provided insight into some of its functions, Rac1 null mice are embryonic lethal and only recently has conditional gene disruption been possible. Consequently, two articles1,2 have recently elucidated some overlapping and unique key roles of Rac1 and Rac2 in haematopoietic processes including specialized roles in innate and humoral immunity. BioEssays 26:221–224, 2004. © 2004 Wiley Periodicals, Inc.
Dynamic regulation of DNA methylation coupled transcriptional repression: BDNF regulation by MeCP2
Authors: Wade Paul A.
Published: February 2004

A recurrent theme in eukaryotic genome regulation stipulates that the properties of DNA are strongly influenced by the nucleoprotein complex into which it is assembled. Methylation of cytosine residues in vertebrate genomes has been implicated in influencing the assembly of locally repressive chromatin architecture. Current models suggest that covalent modification of DNA results in heritable, long‐term transcriptional silencing. In October of 2003, two manuscripts1,2 were published that challenge important aspects of this model, suggesting that modulation of both DNA methylation itself, as well as the machinery implicated in its interpretation, are involved in acute gene regulation. BioEssays 26:217–220, 2004. © 2004 Wiley Periodicals, Inc.
A Global View on Parametric and Nonparametric Approaches to the Analysis of Ordered Categorical Data
Authors: Munzel Ullrich , Langer Frank
Published: February 2004

Rank approaches are very common in the analysis of ordered categorical data but can only be interpreted on an experiment‐wise level. Therefore, parametric tests from linear models, although based on metric structures, are used frequently to analyze this type of data. So the questions arise 1. what parametric tests measure in this context and 2. whether the rank approach could be modified to achieve a global level of interpretation. A possible solution to question 2. offers the so called ridit approach, which is based on known reference distributions. In this paper we discuss a global view that shows how rank analysis and ridit analyses are related and how parametric procedures fit into the same framework. The use of the uniform distribution as a reference in the ridit approach gives an explanation to question 1. The asymptotic multivariate normality of the effect estimators is shown and robust test statistics are discussed. Type I and type II error rates are examined in simulation studies and the approach is applied to a toxicological example. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exact Tests for Comparing Two Paired Proportions with Incomplete Data
Authors: Tang Man‐Lai , Tang Nian‐Sheng
Published: February 2004

Various asymptotic test procedures have been developed previously for testing the equality of two binomial proportions with partially incomplete paired data. Test procedures that discard incomplete observations have been shown to be less powerful than those procedures that utilize all available observations. On the other hand, asymptotic test procedures that utilize all available observations may not be reliable in small‐sample problems or sparse data structures. In this article, unconditional exact test procedures are proposed for testing the equality of two paired binomial proportions with partially incomplete paired data under a random mechanism. The proposed unconditional exact test methods are illustrated with real data from a neurological study. Empirical studies are conducted to investigate the performance of these and other test procedures with respect to size and power. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A New Quantitative Method for Analysing Unreplicated Factorial Designs
Authors: Chen Ying , Kunert Joachim
Published: February 2004

The paper proposes a new method for the analysis of unreplicated factorial designs. The new method does not use an estimate of the error variance and has the potential to identify up to m – 1 active contrasts, where m is the number of contrasts in the study. It can be shown that the proposed test statistic, called MaxUr, is a function of the generalized likelihood ratio test statistic under normality, which was also used by Al‐Shiha and Yang (1999). Our strategy to identify active contrasts using MaxUr, however, is different from the multistage procedure proposed by Al‐Shiha and Yang (1999). Additionally, our simulation study seems to show that the new method is superior to Al‐Shiha and Yang's (1999) method.

In order to test the performance of the new method, we did an extensive simulation study based on 10,000 samples to compare the new method with 12 other methods from the literature. To reasonably compare these methods, some of the 12 existing methods had to be slightly modified, such that the probability of falsely rejecting the global null hypothesis of no active factors was 0.05 for all methods. Two types of evaluation standard were used, the empirical power and the loss of decision. The results show that the new method performs very well, especially for large number of active contrasts (say more than 3 out of 15).

A second purpose of the simulation study was to compare the performance of two well‐known estimates for the variance. One is the PSE introduced by Lenth (1989), the other the ASE introduced by Dong (1993). The simulation study confirmed the approximations of Kunert (1997) which indicate that Dong's (1993) estimate should perform better for small numbers of active factors. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sample Size Calculation for Clinical Studies on the Efficacy of a New Contraceptive Method
Authors: Benda Norbert , Gerlinger Christoph , van der Meulen Egbert A. , Endrikat Jan
Published: February 2004

The current guideline of the European Agency for the Evaluation of Medicinal Products (EMEA) on the clinical investigation of steroid contraceptives in women, which was prepared by the Committee for Proprietary Medicinal Products (CPMP), calls for the calculation of a confidence interval for the Pearl Index, a widely used measure to describe the reliability of a contraceptive method. The key studies should be large enough to give a Pearl Index with a 95% confidence interval such that the difference between the upper limit of the confidence interval and the corresponding point estimate does not exceed a given margin. As a consequence of this guidance, the success probability of a Pearl Index study is given by its capability, i.e. probability to fulfil this criterion. The resulting power function based on the necessary exposure time does not increase strictly. The minimum exposure time Tmin should be calculated such that this function exceeds a given probability for all T ≥ Tmin.

In this paper, the underlying model is discussed, and definitions and formulae are given for the assumption of a Poisson model. The necessary total exposure time is calculated as a function of a given true pregnancy rate.

In addition, some simulations were conducted for the model where a drop‐out mechanism is incorporated into the process. Assuming an exponential distribution for the time to drop‐out the phenomenon that the power does not increase strictly with exposure time is less pronounced. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonparametric One‐way Analysis of Variance of Replicated Bivariate Spatial Point Patterns
Authors: Landau Sabine , Rabe‐Hesketh Sophia , Everall Ian P.
Published: February 2004

A common problem in neuropathological studies is to assess the spatial patterning of cells on tissue sections and to compare spatial patterning between disorder groups. For a single cell type, the cell positions constitute a univariate point process and interest focuses on the degree of spatial aggregation. For two different cell types, the cell positions constitute a bivariate point process and the degree of spatial interaction between the cell types is of interest. We discuss the problem of analysing univariate and bivariate spatial point patterns in the one‐way design where cell patterns have been obtained for groups of subjects. A bootstrapping procedure to perform a nonparametric one‐way analysis of variance of the spatial aggregation of a univariate point process has been suggested by Diggle, Lange and Beneš (1991). We extend their replication‐based approach to allow the comparison of the spatial interaction of two cell types between groups, to include planned comparisons (contrasts) and to assess whole groups against complete spatial randomness and spatial independence. We also accommodate several replicate tissue sections per subject. An advantage of our approach is that it can be applied when processes are not stationary, a common problem in brain tissue sections since neurons are arranged in cortical layers. We illustrate our methods by applying them to a neuropathological study to investigate abnormalities in the functional relationship between neurons and astrocytes in HIV associated dementia. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Online Detection of Monotonic Trends in Time Series
Authors: Fried R. , Imhoff M.
Published: February 2004

The online detection of a monotonic trend in a time series with a time‐varying mean is an important task in medical applications like intensive care monitoring, that is rendered difficult by autocorrelations. Statistical control charts designed for industrial processes are not adequate as they typically rely on a fixed target value, and many detection rules assume a trend to be linear or neglect autocorrelations. We report our experience with the online detection of slow monotonic trends. Our approach is based on a moving time window, and time‐varying autocorrelations are estimated online using parametric assumptions. The performance of versions of this approach is investigated in a simulation study. We find that shrinkage estimation of the time‐varying mean improves the results. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Comparison of Nonparametric Error Rate Estimation Methods in Classification Problems
Authors: Wehberg Sonja , Schumacher Martin
Published: February 2004

Assessment of the misclassification error rate is of high practical relevance in many biomedical applications. As it is a complex problem, theoretical results on estimator performance are few. The origin of most findings are Monte Carlo simulations, which take place in the “normal setting”: The covariables of two groups have a multivariate normal distribution; The groups differ in location, but have the same covariance matrix and the linear discriminant function LDF is used for prediction.

We perform a new simulation to compare existing nonparametric estimators in a more complex situation. The underlying distribution is based on a logistic model with six binary as well as continuous covariables. To study estimator performance for varying true error rates, three prediction rules including nonparametric classification trees and parametric logistic regression and sample sizes ranging from 100‐1,000 are considered. In contrast to most published papers we turn our attention to estimator performance based on simple, even inappropriate prediction rules and relatively large training sets.

For the major part, results are in agreement with usual findings. The most strikingly behavior was seen in applying (simple) classification trees for prediction: Since the apparent error rate Êrr.app is biased, linear combinations incorporating Êrr.app underestimate the true error rate even for large sample sizes. The .632+ estimator, which was designed to correct for the overoptimism of Efron's .632 estimator for nonparametric prediction rules, performs best of all such linear combinations. The bootstrap estimator Êrr.B0 and the crossvalidation estimator Êrr.cv, which do not depend on Êrr.app, seem to track the true error rate. Although the disadvantages of both estimators – pessimism of Êrr.B0 and high variability of Êrr.cv – shrink with increased sample sizes, they are still visible.

We conclude that for the choice of a particular estimator the asymptotic behavior of the apparent error rate is important. For the assessment of estimator performance the variance of the true error rate is crucial, where in general the stability of prediction procedures is essential for the application of estimators based on resampling methods. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Implication of mitochondrial involvement in apoptotic activity of fragile histidine triad gene: Application of synchronous luminescence spectroscopy
Authors: Askari Minoo D. F. , Vo‐Dinh Tuan
Published: February 2004

The fragile histidine triad (FHIT) tumor suppressor gene incorporates the common human chromosomal fragile site at 3p14.2. The structure and expression of the FHIT gene are frequently altered in many cancers. The tumor suppressor activity of the FHIT gene has been previously demonstrated as potentially involving apoptotic induction. Here, mitochondria are implicated as being involved in the apoptotic activity of the FHIT gene. A number of morphological and biochemical events, including the disruption of the inner mitochondrial transmembrane potential (ΔΨm) and the release of apoptogenic cytochrome c protein into the cytoplasm, are characteristic features of the apoptotic program. The proapoptotic activity of the FHIT gene is studied by investigating the loss of ΔΨm in mitochondria and translocation of cytochrome c. Synchronous luminescence (SL) spectroscopy is applied to measure mitochondrial incorporation of rhodamine 123 for direct analysis of alterations in the mitochondrial ΔΨm. The SL methodology is based on synchronous excitation in which the excitation and emission wavelengths are scanned simultaneously while a constant wavelength interval is maintained between the excitation and emission monochromators. An enhanced collapse of ΔΨm in apoptotically induced FHIT expressing cells compared to FHIT negative cells is observed. The loss of ΔΨm is greatly restricted in the presence of the apoptotic inhibitor, cyclosporin A. Cytoplasmic translocation of cytochrome c in the FHIT expressing cells as an early event in apoptosis is also demonstrated. It is concluded that Fhit protein expression maintained apoptotic function by altering the ΔΨm and by enhancing cytochrome c efflux from the mitochondria. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Spectroscopic evidence revealing polyproline II structure in hydrophobic, putatively elastomeric sequences encoded by specific exons of human tropoelastin
Authors: Bochicchio Brigida , Aït‐Ali Amina , Tamburro Antonio M. , Alix Alain J. P.
Published: February 2004

Elastin, the protein responsible for tissue elasticity, is contained in arterial walls, lungs, and skin. Given the cassettelike organization of the human tropoelastin gene, giving rise to alternating exons encoding for crosslink domains and elastomeric domains, it is tempting to suggest that polypeptides encoded by different exons could adopt structures independent of the other exons. The results obtained with the polypeptide sequences encoded by exons 3, 7, and 30 of human tropoelastin are described. It is shown that these hydrophobic exons may partly assume the polyproline II (PPII) structure, as found by circular dichroism studies in aqueous solution. Classical Raman spectroscopy evidences a specific sharp band at 1314 cm−1, which is assigned to the PPII structure adopted by these exons in the solid state. As these sequences are among those putatively responsible for elastomeric properties, these findings are of particular interest in relation to the current models of the elasticity of elastin. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Schiff base of gossypol with 3,6,9‐trioxa‐decylamine complexes with monovalent cations studied by mass spectrometry, 1H‐NMR, FTIR, and PM5 semiempirical methods
Authors: Przybylski Piotr , Ilkevych Nataliya , Schroeder Grzegorz , Brzezinski Bogumil , Bartl Franz
Published: February 2004

A new Schiff base of gossypol with 3,6,9‐trioxa‐decylamine (GSTB) forms stable complexes with monovalent cations. This process of complex formation was studied by electrospray ionization mass spectrometry, 1H‐NMR and FTIR spectroscopy, and the PM5 (parametric method 5) semiempirical method. It is found that GSTB forms 1 : 1 and 1 : 2 complexes with Li+ and Na+ and 1 : 1 complexes with K+, Rb+, or Cs+ cations and exists in all these complexes in the enamine–enamine tautomeric form. Moreover, within these complexes only Li+ cations can fluctuate between the oxygen atoms of trioxaalkyl chains. All other cations are strongly localized. In the complex of GSTB with two protons localized on the N atoms of the Schiff base, the imine–imine tautomeric form is realized. The complexes of the Schiff base with K+, Rb+, or Cs+ cations are the 1 : 1 type with the oxygen atoms of the trioxaalkyl chains, as well as the O1H or O1′H group coordinating the cation. The structures of the complexes are calculated by the PM5 semiempirical method and discussed. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Studies on acute human infections using FTIR microspectroscopy and cluster analysis
Authors: Mordehai Jacov , Ramesh Jagannathan , Huleihel Mahmoud , Cohen Zahavi , Kleiner Oleg , Talyshinsky Marina , Erukhimovitch Vitaly , Cahana Aviv , Salman Ahmad , Sahu Ranjit Kumar , Guterman Hugo , Mordechai Shaul
Published: February 2004

A novel methodology for the diagnosis of acute infections using FTIR microspectroscopy (FTIR‐MSP) data on blood components and cluster analysis is presented. Blood samples were collected from 11 patients suffering from various infections and 16 age‐matched healthy human controls. Blood components such as white blood cells, red blood cells, and plasma were isolated using standard procedures and FTIR‐MSP of these components was utilized. A cluster analysis of the FTIR spectra was performed. The spectra obtained from the three blood components of patients were different from those of controls. The FTIR spectra of white blood cells from patients suffering infections were significantly different from the controls. Cluster analyses of averaged FTIR‐MSP spectra of white blood cells provided 100% classification between patients and healthy controls. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Inclusion complex of fenbufen with β‐cyclodextrin
Authors: Bratu I. , Gavira‐Vallejo J. M. , Hernanz A. , Bogdan M. , Bora Gh.
Published: February 2004

An inclusion complex of fenbufen with β‐cyclodextrin (β‐CD) in aqueous solution was characterized by 1H‐NMR spectroscopy. The [1:1] stoichiometry was determined and a stability constant of several 1000s (M−1) was calculated. The geometry of the inclusion complex was established based on MM+ molecular mechanics calculations. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Fourier transform infared spectroscopy investigation of protein conformation in spray‐dried protein/trehalose powders
Authors: French Donna L. , Arakawa Tsutomu , Li Tiansheng
Published: February 2004

Spray drying is a way to generate protein solids (powders), which is also true for lyophilization. Sugars are used to protect proteins from conformational changes and chemical degradations arising from drying processes and storage conditions such as the humidity. The influence of trehalose and humidity on the conformation and hydration of spray‐dried recombinant human granolucyte colony stimulating factor (rhG‐CSF) and recombinant consensus interferon‐α (rConIFN) was investigated using Fourier transform IR spectroscopy. The spectral analysis of spray‐dried powders in the amide I region demonstrated that trehalose stabilized the α‐helical conformation of both rhG‐CSF and rConIFN proteins. Exposure of the pure protein powders to 33% relative humidity (RH) resulted in the formation of β sheets and loss of turns but no change in α‐helical structure. Trehalose reduced the magnitude of the changes in β sheets and turns. Exposure of the pure protein powders to 75% RH resulted in the loss of α‐helical conformation with a corresponding increase in β structures (β sheets and turns). Trehalose did not protect proteins from the loss of α‐helical structures, but it reduced the formation of antiparallel β sheets. Hydrogen–deuterium exchange (H–D exchange) was used to further characterize these hydration‐induced conformational changes. At 33% RH the percent exchange of the protein decreased with increasing trehalose content, indicating a greater protection of the protein from H–D exchange by a higher concentration of trehalose. Such protection correlates with decreased conformational changes of the protein by trehalose at this humidity. At 75% RH the degree of H–D exchange of the protein was insensitive to the powder composition in all powders. Surprisingly, the H–D exchange of trehalose was low at about 20–25%, which was nearly independent of the protein/trehalose ratio and humidity, indicating that the exchangeable protons on trehalose molecules are highly protected in protein‐containing powders. The observed protein hydration is related to the effect of trehalose on the conformational changes of the protein under humidity. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Interactions of Alzheimer amyloid peptides with cultured cells and brain tissue, and their biological consequences
Authors: Bateman David A. , Chakrabartty Avijit
Published: February 2004

The Alzheimer amyloid peptides are the main constituent of the diagnostic hallmark of Alzheimer disease, the senile plaque. A halo of neurodegeneration surrounds the senile plaques observed in the brains of Alzheimer patients. Significant efforts are under way to determine whether the Alzheimer peptides are the causal agents of this neurodegeneration. We review the developments in identifying the putative interaction sites of Alzheimer amyloid peptides on cells and intact brain tissue. We focus on the specificity of this interaction and on the molecular nature of potential receptors. These studies form the bases for developing therapeutics that target potential interaction sites and inhibit Alzheimer amyloid peptide deposition. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004
External reversible control of recognition behavior of alpha‐peptide ribonucleic acid (α‐PRNA) through anti‐syn orientational switching of the nucleobase induced by borate esterification of the cis‐2′,3′‐diol
Authors: Wada Takehiko , Sato Hirofumi , Inoue Yoshihisa
Published: February 2004

A novel nucleic acid model using peptide ribonucleic acid (PRNA), which contains 5′‐amino‐5′‐deoxypyrimidine ribonucleoside as a recognition site for nucleic acids, has been designed, synthesized and applied to the external reversible control of recognition behavior of the complementary polynucleotide through the orientational switching of the nucleobase induced by borate. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004