bluuebunny/crossref_metadata_2025 huggingface dataset:
Biliary Excretion of Antimicrobial Drugs
Authors: Karachalios George , Charalabopoulos Konstantinos
Published: April 2003

The development of drugs able to prevent and cure bacterial infections is one of the 20th century’s major contributions to human longevity and quality of life. Antibacterial agents are among the most commonly prescribed drugs of any kind worldwide. Used appropriately, these drugs are lifesaving. To eliminate an infection as rapidly as possible, a sufficient concentration of the drug(s) chosen must reach the site of infection. Serum/tissue concentration is a result of various parameters such as absorption, excretion, protein binding and metabolic inactivation. Biliary excretion is an important route for the elimination of some drugs and drug metabolites in humans. Thus, drugs with a high bile concentration are indicated for the treatment of gallbladder infectious diseases. We present a review of a large number of antimicrobial agents most commonly used in daily clinical practice, with regard to their biliary excretion.
Consistently Low Hepatitis B Virus DNA Saves Patients from Hepatocellular Carcinogenesis in HBV-Related Cirrhosis
Authors: Ikeda Kenji , Arase Yasuji , Kobayashi Masahiro , Someya Takashi , Saitoh Satoshi , Suzuki Yoshiyuki , Suzuki Fumitaka , Tsubota Akihito , Akuta Norio , Kumada Hiromitsu
Published: April 2003

Background: To elucidate the influence of serum hepatitis B virus (HBV) load on hepatocellular carcinogenesis in cirrhotic patients, HBV-DNA was sequentially measured. Patients and Methods: Among 160 consecutive patients with HBV-related cirrhosis who received no anti-viral therapy, serial assay of HBV-DNA concentration was available in 146 (91.3%): 48 developed hepatocellular carcinoma (HCC) and 98 did not during a median of 11.7 years. HBV-DNA of 103.7 copies/ml or less was considered as low. Results: Of the 48 cases with eventual HCC development (group A), 9 showed intermittently high HBV-DNA, and the other 39 persistently high values. Among 48 age- and sex-matched control patients (group B) selected from the 98 HCC-free patients, 9 had continuously low HBV-DNA, 13 showed a settled down course of HBV-DNA, 9 intermittently high, and the remaining 17 patients demonstrated continuously high HBV-DNA. High HBV-DNA in the last 3 years was significantly associated with carcinogenesis (group A; 0/48 vs. group B; 22/48, p < 0.0001). No patient with a continuously low HBV-DNA for the last 3 years developed HCC. Conclusion: Persistence of high HBV-DNA concentration suggested an increased risk of carcinogenesis. Sequential analysis of HBV-DNA is important in the assessment of the carcinogenesis risk.
Adeno-Associated Virus Type 2 Rep40 Modulates the Proliferation Rate of Rep52-Expressing HeLa Cells
Authors: Li Donglan , Kashii Saburo , Sahara Toshiyuki , Ito Kazuhiko
Published: April 2003

Objective: To investigate the growth-inhibitory effect of Rep proteins on cells. Methods: We generated Rep-expressing plasmids that containing wild-type rep genes or mutant rep genes with point mutations in their ATP-binding sites. We obtained several HeLa cell clones expressing Rep proteins constitutively by the regulator plasmid. The expression of each Rep protein was detected by Western blotting with an anti-Rep monoclonal antibody. Results: Clones that expressed Rep52 and Rep40 grew more slowly than those which exhibited no detectable expression of Rep or mutant Rep protein. In contrast, clone w-33, which proliferated as quickly as control HeLa cells, expressed only Rep40. By comparing the expression levels of Rep proteins in these clones, we found that the ratio of Rep40 to Rep52 gradually increased in the faster growing clones. Conclusion: These results suggest that while Rep52 expression retards cell proliferation, Rep40 promotes recovery from Rep52-induced HeLa cell growth inhibition.
Viral Zoonoses – A Threat under Control?
Authors: Ludwig B. , Kraus F.B. , Allwinn R. , Doerr H.W. , Preiser W.
Published: April 2003

Despite intensive research and considerable effort to eradicate infectious diseases, modern medicine has failed to control many infectious diseases which have been thought to be easy to overcome with advances in medical science and technology. In fact, infectious diseases remain a dominant feature in public health considerations for the 21st century. Some infectious agents already known to be pathogenic have gained increasing importance in recent decades due to changes in disease patterns. Furthermore, many new, previously unknown infectious agents with a high pathogenic potential have been identified. Nearly all of these emergent disease episodes have involved zoonotic or species-jumping infectious agents. The complex interaction of factors like environmental and ecological changes, social factors, decline of health care, human demographics and behaviour influences the emergence of re-emergence of such diseases. Viruses, especially RNA viruses with their ability to adapt quickly to changing environmental conditions, are among the most prominent examples of emerging pathogens. In this review, we present the important examples of zoonotic viruses and discuss the factors playing a key role in the emergence and resurgence of these diseases.
Cyclic GMP Mediates Influence of Macula densa Nitric Oxide over Tubuloglomerular Feedback
Authors: Thomson Scott C. , Deng Aihua
Published: April 2003

Background: Tubuloglomerular feedback (TGF) stabilizes nephron function by eliciting reciprocal changes in single-nephron glomerular filtration rate in response to changes in salt reaching the macula densa. Nitric oxide (NO) modulates TGF, making it less reactive. NO could come from NO synthase (NOS) in mesangium or microvessels (NOS III) or from neuronal NOS (NOS I) in the macula densa. Cyclic GMP is second messenger for many NO functions. Methods: Rat micropuncture was performed to confirm that macula densa NOS I makes the NO which modulates TGF and that cyclic GMP is a second messenger for this. The range of TGF was determined by measuring the single-nephron glomerular filtration rate while perfusing Henle’s loop. The TGF slope was calculated from the response to flow perturbations in free-flowing nephrons using a noninvasive optical technique to measure flow. The NO-cyclic GMP axis was manipulated by tubular microperfusion of the antagonists S-methyl-thiocitrulline (SMTC) and 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ) and NO donor (spermine NONOate). Results: SMTC and ODQ each increased slope and range of TGF and tended to shift it leftward. NONOate reversed the effects of SMTC, but not of ODQ. Conclusion: Cyclic GMP mediates desensitization of TGF by macula densa NOS I.
Chromosomal characteristics of ribosomal DNA in two extant species of North American mudminnows Umbra pygmaea and U. limi (Euteleostei: Umbridae)
Authors: Ráb P. , Crossman E.J. , Reed K.M. , Rábová M.
Published: April 2003

The locations and chromosomal characteristics of ribosomal DNA (rDNA) sites in the karyotypes of two extant North American species of mudminnows, Umbra pygmaea and U. limi (2n = 22, NF = 44), were analyzed sequentially by conventional Giemsa staining, Ag staining, CMA3 fluorescence and fluorescence in situ hybridization (FISH). The nucleolar organizer regions (NORs) were located in the fourth chromosomal pair in both species (pericentromeric region in U. pygmaea and subtelomeric in U. limi). These sites were strongly CMA3-positive suggesting that the rDNA sites in these species are associated with GC-rich DNA. FISH with a rDNA probe gave consistently positive signals in the same regions detected by Ag-staining and CMA3-fluorescence. However, both species also had additional CMA3-positive/Ag-negative heterochromatic blocks at pericentrometric regions of several chromosomal pairs (three in U. pygmaea and five in U. limi). FISH revealed additional rDNA clusters in both species. It is hypothesized that a paracentric inversion of the chromosome arm carrying the NORs might be one of the rearrangements differentiating the karyotypes of two North American species. The presence of additional rDNA sites is indicative of more complex rearrangements. The pericentromeric NOR phenotype of Umbra pygmaea is similar to that seen in U. krameri and in the distantly related genus Esox.
Chromosome location and characterization of the human nicotinic acetylcholine receptor subunit alpha (α) 9 (CHRNA9) gene
Authors: Lustig L.R. , Peng H.
Published: April 2003

The human nicotinic acetylcholine receptor (nAChR) subunit α9 gene (CHRNA9) codes for a component of the AChR in hair cells of the inner ear. While no direct evidence presently links this gene to known hearing disorders, it may underlie individual susceptibility to acoustic inner ear injury, and is associated with the autoimmune skin disorder Pemphigus vulgaris. Future studies will depend upon a thorough characterization of the nAChR α9 gene. CHRNA9 was localized to chromosome 4p15.1→p14 by FISH analysis. Radiation hybrid mapping further localized the gene between markers D4S405 and D4S496 (Stanford G3 panel), and between markers WI-3875 and D4S1231 (Genebridge 4 panel), representing a distance of approximately 3.1 cR. The D4S405 marker has been linked to a non-syndromic form of hereditary hearing loss, DFNB-25. The gene contains five exons, separated by four introns. Exons 1–5 are 78, 145, 154, 532 and 877 bases, respectively. Introns 1–4 are 294, 1239, 11517, and 4571 bases, respectively. The intron-exon splice junction sites correlate identically with those of the rat α9 gene and are nearly identical to those of the human α10 gene. Sequence promoter analysis reveals a number of potential regulatory elements, including several in common with the nAChR α10 gene, whose expressed protein is assumed to combine with α9 in the inner ear.
Identification and characterization of a novel ABCA subfamily member, ABCA12, located in the lamellar ichthyosis region on 2q34
Authors: Annilo T. , Shulenin S. , Chen Z.Q. , Arnould I. , Prades C. , Lemoine C. , Maintoux-Larois C. , Devaud C. , Dean M. , Denèfle P. , Rosier M.
Published: April 2003

The ABCA subfamily of ABC transporters includes ten members to date. In this study, we describe an additional gene, ABCA12. Four full-length cDNA sequences have been obtained from human placenta that contain two different polyadenylation sites and two splicing forms, coding for ABCA12 isoforms of 2,595 and 2,516 amino acid residues. Both isoforms are predicted to have two ATP-binding domains (nucleotide binding domain, NBD) and two transmembrane (TM) domains, features shared by all other ABCA subfamily proteins. ABCA12 is most closely related to ABCA1, with an amino acid similarity of 47%. Northern blot analysis demonstrates that a 9.5-kb transcript is mainly expressed in the stom- ach. ABCA12 was mapped to human chromosome 2q34. Two other genes from ABCA subfamily are associated with human inherited diseases, ABCA1 with the cholesterol transport disorders Tangier disease and familial hypoalphalipoproteinemia, and ABCA4 with several retinal degeneration disorders. The ABCA12 gene is located in a region of chromosome 2q34 that harbors the genes for lamellar ichthyosis, polymorphic congenital cataract, and insulin-dependent diabetes mellitus (IDDM13), and therefore is a positional candidate for these pathologies.
Demystifying chromosome preparation and the implications for the concept of chromosome condensation during mitosis
Authors: Claussen U. , Michel S. , Mühlig P. , Westermann M. , Grummt U.-W. , Kromeyer-Hauschild K. , Liehr T.
Published: April 2003

The processes taking place during routine chromosome preparation are not well understood. In this study, the morphological changes in amniotic fluid cells, blood lymphocytes, and bone marrow cells in the metaphase stage were examined under an inverted microscope during chromosome preparation. The putative processes that occur during chromosome preparation were simulated in suspension, and the cells were treated with different mixtures of hypotonic solution, fixative, methanol, acetic acid, and water. Evaporation of the fixative was performed under normal atmospheric conditions and under vacuum at different levels of humidity. Freeze fracture electron microscopy was used to analyze the effects of fixative on the cell membrane. Confocal microscopic analysis was used to investigate three-dimensionally the effects of hypotonic treatment on the positions of chromosomes in fixed mitotic lymphocytes. Chromosome preparation-induced changes in the lengths of single chromosomes were also investigated. The results show that chromosome spreading involves significant water-induced swelling of mitotic cells during evaporation of the fixative from the slide, which is a prerequisite for chromosomal elongation, the production of metaphase spreads for chromosome analysis, and the appearance of Giemsa banding patterns. Hypotonic treatment is essential for well-spread metaphase chromosomes because it moves the chromosomes from a central to a more peripheral position in the cell, where they can be stretched more effectively during mitotic swelling. Like mitotic cells, isolated single chromosomes also have their own potential to swell and lengthen during chromosome preparation. We hypothesize that chromosome preparation leads to a genome-wide chromosomal region–specific opening of chromatin structures as GTG-light bands and sub-bands. Living cells may possess a similar mechanism, which is used only to open single chromatin structures to facilitate transcription. We propose the concept of chromosomal region–specific protein swelling.
Spacer Fabrics – A Potential Tool in the Prevention of Chronic Wounds
Authors: Wollina Uwe , Heide Marianne , Swerev Maximilan
Published: April 2003

Spacer fabrics are special textiles that offer designed qualities for pressure relief as well as regulation of heat and moisture. Investigations of the physical properties of these textiles demonstrate favourable qualities for their potential use in the medical field. The application of spacer fabrics for the prevention of chronic wounds is just beginning. However, typical fields of application are primary prevention of pressure sores in the operation room, secondary prevention of pressure sores for wheelchair drivers and the prevention of plantar ulcers in patients with the diabetic foot syndrome. Spacer-fabric-based bandages seem to be useful in oedema treatment in cases of chronic venous insufficiency and chronic lymphatic insufficiency.
Complete reconstitution of human lymphocytes from cord blood CD34+ cells using the NOD/SCID/γcnull mice model
Authors: Hiramatsu Hidefumi , Nishikomori Ryuta , Heike Toshio , Ito Mamoru , Kobayashi Kimio , Katamura Kenji , Nakahata Tatsutoshi
Published: April 2003

Establishment of an assay capable of generating all classes of human lymphocytes from hematopoietic stem cells (HSCs) will provide new insight into the mechanism of human lymphopoiesis. We report ontogenic, functional, and histologic examination results of reconstituted human lymphocytes in NOD/SCID/ γcnull mice after the transplantation of human cord blood (CB) CD34+ cells. After transplantation, human B, natural killer (NK), and T cells were invariably identified in these mice, even though no human tissues were cotransplanted. Immature B cells resided mainly in bone marrow (BM), whereas mature B cells with surface immunoglobulins were preferentially found in spleen. NK cells were identified in BM and spleen. T cells were observed in various lymphoid organs, but serial examinations after transplantation confirmed human T lymphopoiesis occurring in the thymus. These human lymphocytes were also functionally competent. Human immunoglobulin M (IgM), IgA, and IgG were detected in the sera of these mice. T cells showed a diverse repertoire of T-cell–receptor Vβ (TCR Vβ) chains, proliferated in response to phytohemagglutinin, and were cytotoxic against cell lines. NK activity was demonstrated using the K562 cell line. Immunohistochemical analysis revealed that human lymphocytes formed organized structures in spleen and thymus that were analogous to those seen in humans. In the thymus, CD4 and CD8 double-positive T cells were predominant and coexpressed CD1a and Ki-67, thereby supporting the notion that T lymphopoiesis was taking place. NOD/SCID/ γcnull mice provide a unique model to investigate human lymphopoiesis without the cotransplantation of human tissues.
Quality of Non–Breast Cancer Health Maintenance Among Elderly Breast Cancer Survivors
Authors: Earle Craig C. , Burstein Harold J. , Winer Eric P. , Weeks Jane C.
Published: April 2003

Purpose: To assess the quality of preventive health care, the role of health care participation, and the patient and provider characteristics associated with high-quality care for breast cancer survivors.

Methods: We analyzed the 1997 to 1998 Medicare data of elderly women who were diagnosed with nonmetastatic breast cancer in 1991 or 1992 while living in a Survival, Epidemiology, and End Results (SEER) tumor registry area and who survived to the end of 1998 without evidence of cancer recurrence. Controls were matched for age, race, and geographic location.

Results: The 5,965 breast cancer survivors received more preventive services (influenza vaccination, lipid testing, cervical and colon screening, and bone densitometry) than matched controls. Among both groups, those who were younger, non–African-American, of higher socioeconomic status, living in urban areas, and receiving care in a teaching center were most likely to receive high-quality health maintenance. Those survivors who continued to see oncology specialists were more likely to receive appropriate follow-up mammography for their cancer, but those who were monitored by primary care physicians were more likely to receive all other non–cancer-related preventive services. Those who saw both types of practitioners received more of both types of services. When the control group was restricted only to women actively undergoing mammographic screening before the study period, receipt of preventive services was similar.

Conclusion: Breast cancer survivors receive high-quality preventive services, but disparities on the basis of nonmedical factors still exist. Cancer follow-up may provide regular contact with the health system, maximizing the likelihood of receiving appropriate general medical care.
Risk Factors for Relapse in Clinical Stage I Nonseminomatous Testicular Germ Cell Tumors: Results of the German Testicular Cancer Study Group Trial
Authors: Albers Peter , Siener Roswitha , Kliesch Sabine , Weissbach Lothar , Krege Susanne , Sparwasser Christoph , Schulze Harald , Heidenreich Axel , de Riese Werner , Loy Volker , Bierhoff Erhard , Wittekind Christian , Fimmers Rolf , Hartmann Michael
Published: April 2003

Purpose: To prospectively assess potential risk factors for relapse in clinical stage I nonseminomatous germ cell tumors of the testis (CS I NSGCT).

Patients and Methods: From September 1996 to May 2002, 200 patients with CS I NSGCT were prospectively assigned to retroperitoneal lymph node dissection (RPLND), and risk factor assessment was performed within a multicenter protocol. One hundred sixty-five patients had an adequate minimum follow-up of 12 months (mean, 34.5 months) or had pathologic stage II.

Results: Pathologic stage II disease was found in 27.9% of patients. Only 0.6% of patients relapsed in the retroperitoneum after confirmation of pathologic stage I disease. With reference pathology, vascular invasion (VI) was most predictive of stage in multifactorial analysis (accuracy, 65.1%). However, the positive predictive value (PPV) of VI to predict patients who have metastatic disease or relapse during follow-up was only 52.7%. With absent VI, low-risk patients had a negative predictive value (NPV) of 76.9%. With a combination of several risk factors, the PPV increased to 63.6% and the negative predictive value increased to 86.5%.

Conclusion: Even with an optimal combination of prognostic factors and reference pathology, more than one third of patients predicted to have pathologic stage II or relapse during follow-up will not harbor metastatic disease and, therefore, would be overtreated with adjuvant therapy. However, patients at low risk may be predicted at an 86.5% level, and thus, surveillance in highly compliant patients would be a valuable option. For high-risk patients, further reduction of adjuvant treatment is necessary.
Allogeneic Stem-Cell Transplantation From Related and Unrelated Donors in Older Patients With Myeloid Leukemia
Authors: Bertz Hartmut , Potthoff Karin , Finke Jürgen
Published: April 2003

Purpose: To improve outcome for older patients with poor-prognosis myeloid malignancies by using allogeneic hematopoietic stem-cell transplantation (alloHSCT) from unrelated and sibling donors after reduced-intensity conditioning (RIC).

Patients and Methods: Nineteen older patients (median age, 64 years; range, 60 to 70 years) with active myeloid malignancies were treated with an RIC regimen that was based on fludarabine, melphalan, and carmustine followed by alloHSCT from matched unrelated (n = 12) or sibling donors (n = 7). Before transplantation, patients had a median of 50% bone marrow blasts (range, 0% to 70%). Graft-versus-host-disease (GvHD) prophylaxis consisted of cyclosporine and mycophenolate mofetil or methotrexate. Eleven of 12 patients with an unrelated donor also received anti–T-lymphocyte globulin (ATG).

Results: Engraftment was successful for all 19 patients. Seventeen assessable patients achieved complete response (CR). Four patients experienced relapse; three achieved CR again after donor lymphocyte infusion (n = 1) or a second alloHSCT (n = 2). Six patients died as a result of relapse (n = 2), GvHD-associated complications (n = 2), or fungal infections (n = 2), resulting in a 1-year nonrelapse mortality rate of 22%. With a median follow-up of 825 days (range, 595 to 1,028 days), 13 of 19 patients are alive, resulting in a 1-year survival rate of 68% (95% confidence interval, 48% to 89%).

Conclusion: In older patients with untreated poor-prognosis leukemia, this RIC regimen combined with alloHSCT sufficiently reduces the leukemic burden, resulting in a high CR rate. When ATG is added, matched unrelated donor transplantation can be performed safely in older patients. For these patients, early transplantation after diagnosis offers a fair chance of cure.
A Novel Insulin-Like Growth Factor (IGF)-Independent Role for IGF Binding Protein-3 in Mesenchymal Chondroprogenitor Cell Apoptosis
Authors: Longobardi Lara , Torello Monica , Buckway Caroline , O’Rear Lynda , Horton William A. , Hwa Vivian , Roberts Charles T. , Chiarelli Francesco , Rosenfeld Ron G. , Spagnoli Anna
Published: April 2003

Chondrogenesis results from the condensation of mesenchymal chondroprogenitor cells (MCC) that proliferate and differentiate into chondrocytes. We have previously shown that IGF binding protein (IGFBP)-3 has an IGF-independent antiproliferative effect in MCC. The current study evaluates the IGF-independent apoptotic effect of IGFBP-3 on MCC to modulate chondrocyte differentiation. We employed the RCJ3.1C5.18 chondrogenic cell line, which in culture progresses from MCC to differentiated chondrocytes; cells do not express IGFs or IGFBP-3. We also used IGFBP-3 mutants with decreased (I56 substituted to G56; L80 and L81 to G80G81) or abolished binding for IGFs (I56, L80, and L81 to G56G80G81). MCC transfected with IGFBP-3 detached, changed their phenotype, and underwent apoptosis. A maximal IGFBP-3 apoptotic effect was observed 24 h after transfection (463 ± 73% of controls; P < 0.001). Remarkably, IGFBP-3 mutants had similar effects, demonstrating that the IGFBP-3 apoptotic action was clearly IGF independent. In addition, treatment with IGFBP-3 in serum-free conditions resulted in a significant increase of apoptosis (173 ± 23% of controls; P < 0.05). Moreover, this apoptotic effect was selective for MCC, resulting in a selective reduction of chondrocytic nodules and a significant decrease in type II collagen expression and proteoglycan synthesis. In summary, we have identified a novel IGF-independent role for IGFBP-3 in the modulation of chondrocyte differentiation.
Self-Assembly and Substituent Effect of Copper(I) Complexes with 1,2-Bis(2-pyridylethynyl)benzene Ligands
Authors: Kawano Tomikazu , Kuwana Jun , Ueda Ikuo
Published: April 2003

The reaction of 1,2-bis(2-pyridylethynyl)benzenes (L1–L5) with copper(I) ions proceeded smoothly to afford mononuclear copper(I) chelate complexes CL1–CL3 or dinuclear copper(I) molecular rectangular boxes, CL4 and CL5, in excellent yields, depending on the size of the substituent. If a ligand with a small substituent was used, the self-assembly of a mononuclear copper(I) chelate complex was achieved. If a ligand with a bulky substituent was used, the self-assembly of dinuclear copper(I) molecular rectangular boxes was achieved. The equilibrium between these two copper(I) complexes was also observed in solution.
Variance Reduction Techniques for Estimating Value-at-Risk
Authors: Glasserman Paul , Heidelberger Philip , Shahabuddin Perwez
Published: April 2003

This paper describes, analyzes and evaluates an algorithm for estimating portfolio loss probabilities using Monte Carlo simulation.Obtaining accurate estimates of such loss probabilities is essential to calculating value-at-risk, which is a quantile of the loss distribution. The method employs a quadratic (“delta-gamma”) approximation to the change in portfolio value to guide the selection of effective variance reduction techniques;specifically importance sampling and stratified sampling.If the approximation is exact, then the importance sampling is shown to be asymptotically optimal.Numerical results indicate that an appropriate combination of importance sampling and stratified sampling can result in large variance reductions when estimating the probability of large portfolio losses.
Stochastic Prediction in Multinomial Logit Models
Authors: Hsu Arthur , Wilcox Ronald T.
Published: April 2003

It is standard practice to form predictions from multinomial logit models by ignoring the estimation error associated with the parameter estimates and solving for the predicted endogeneous variable (market share) in terms of the exogenous variables and the point estimates of the parameters. It has long been recognized in the econometrics literature that this type of nonstochastic prediction, which ignores the sampling distribution of the parameter estimates, leads to incorrect inferences about the endogenous variable. We offer a simulationbased approach for approximating the exact stochastic prediction. We show that this approach provides very accurate approximations with minimal computation time and would be easy to implement in industrial applications.
A Further Extension of the KKMS Theorem
Authors: Kannai Yakar , Wooders Myrna H.
Published: April 2003

Reny and Wooders (1998) showed that there is some point in the intersection of sets in Shapley's (1973) generalization of the Knaster-Kuratowski-Mazurkiwicz Theorem with the property that the collection of all sets containing that point is partnered as well as balanced. We provide a further extension by showing that the collection of all such sets can be chosen to be strictly balanced, implying the Reny-Wooders result. Our proof is topological, based on the Eilenberg-Montgomery Fixed Point Theorem. Reny and Wooders (1998) also show that if the collection of partnered points in the intersection is countable, then at least one of them is minimally partnered. Applying degree theory for correspondences, we show that if this collection is assumed to be zero-dimensional, then there is at least one strictly balanced and minimally partnered point in the intersection. Our approach sheds a new geometric-topological light on the Reny-Wooders results.
On Two-Player Repeated Games with Lack of Information on One Side and State-Independent Signalling
Authors: Renault Jérôme
Published: April 2003

We consider two-person undiscounted repeated games with lack of information on one side and state-independent signalling and prove the existence of a “joint plan” uniform equilibrium.
Aggregation Error Bounds for a Class of Location Models
Authors: Francis R. L. , Lowe T. J. , Tamir Arie
Published: April 2003

Many location models involve distances and demand points in their objective function. In urban contexts, there can be millions of demand points. This leads to demand point aggregation, which produces error. We identify a general model structure that includes most such location models, and present a means of obtaining error bounds for all models with this structure. The error bounds suggest how to do the demand point aggregation so as to keep the error small.
When Market Information Constitutes Fields: Sensemaking of Markets in the Commercial Music Industry
Authors: Anand N. , Peterson Richard A.
Published: April 2003

In this paper we outline a key mechanism through which organizational fields are constituted. We suggest that in competitive fields, the market serves as a magnet around which groups of actors consolidate, and that cognition of markets occurs through the creation, distribution, and interpretation of a web of information about the “market.” To illustrate our theory, we present a case study of the Billboard music chart from the commercial music industry to show that changes in either scope, methodology, or political tone with which market information is presented can provide a major jolt to the participants' understanding of their field.
Prevention of Hip Fractures by External Hip Protectors
Authors: van Schoor Natasja M. , Smit Johannes H. , Twisk Jos W. R. , Bouter Lex M. , Lips Paul
Published: April 2003

Context

Several randomized controlled trials have been performed to examine the effectiveness of external hip protectors in reducing the incidence of hip fractures, but the results are controversial.

Objective

To examine the effectiveness of hip protectors in reducing the incidence of hip fractures in an elderly high-risk population.

Design, Setting, and Participants

Randomized controlled trial of elderly persons aged 70 years or older, who have low bone density, and are at high risk for falls. Participants lived in apartment houses for the elderly, homes for the elderly, and nursing homes in Amsterdam and surrounding areas in the Netherlands. They were enrolled in the study between March 1999 and March 2001; the mean follow-up was 69.6 weeks. Of the 830 persons who were screened, 561 persons were enrolled.

Intervention

External hip protector. Both groups received written information on bone health and risk factors for falls.

Main Outcome Measure

Time to first hip fracture. Survival analysis was used to include all participants for the time they participated.

Results

In the intervention group, 18 hip fractures occurred vs 20 in the control group. Four hip fractures in the intervention group occurred while an individual was wearing a hip protector. At least 4 hip fractures in the intervention group occurred late at night or early in the morning. Both in univariate analysis (log-rank P = .86) and in multivariate analysis (hazard ratio [HR], 1.05; 95% confidence interval [CI], 0.55-2.03), no statistically significant difference between the intervention group and control group was found with regard to time to first hip fracture. In addition, the per protocol analysis in compliant participants did not show a statistically significant difference between the groups (HR, 0.77; 95% CI, 0.25-2.38).

Conclusion

The hip protector studied was not effective in preventing hip fractures.
Reproductive adaptations to a large‐brained fetus open a vulnerability to anovulation similar to polycystic ovary syndrome
Authors: Barnett Deborah K. , Abbott David H.
Published: April 2003

During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen‐induced proliferation and growth of the uterine endometrium prior to progesterone‐induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen‐induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large‐brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS. Am. J. Hum. Biol. 15:296–319, 2003. © 2003 Wiley‐Liss.
Human physiological adaptation to pregnancy: Inter‐ and intraspecific perspectives
Authors: Rockwell L. Christie , Vargas Enrique , Moore Lorna G.
Published: April 2003

Reproductive success requires successful maternal physiological adaptation to pregnancy. An interspecific perspective reveals that the human species has modified features of our haplorhine heritage affecting the uteroplacental circulation. We speculate that such modifications — including early implantation and deep, widespread invasion of fetal (trophoblast cells) into and resultant remodeling of maternal uterine vessels — are responses to or compensation for the biomechanical constraints imposed by bipedalism which, in turn, render our species susceptible to the pregnancy complication of preeclampsia. Preeclampsia is characterized by incomplete remodeling of maternal uterine vessels as the result of shallow trophoblast invasion, which in turn reduces uteroplacental blood flow and frequently leads to intrauterine growth restriction (IUGR). Using an intraspecific perspective, we consider the fitness‐related consequences of variation in uteroplacental blood flow during high‐altitude pregnancy. Although birth weights are reduced at high altitudes in Bolivia, multigenerational Andean residents are relatively protected from altitude‐associated IUGR. Our preliminary data suggest that Andean women have greater uteroplacental oxygen delivery than European high‐altitude residents due to more complete growth and remodeling of maternal uterine vessels. Identification of the physiological and genetic mechanisms involved in such inter‐ and intraspecific variations in pregnancy physiology will likely be useful for understanding human evolution and contemporary challenges to successful reproduction. Am. J. Hum. Biol. 15:330–341, 2003. © 2003 Wiley‐Liss, Inc.
Reproductive success: Which meaning?
Authors: Crognier E.
Published: April 2003

The theory of kin selection (the part played by behavior in the changes of mean inclusive fitness) induced many human sociobiologists to think that since behavior was involved in the increase in fitness, this last entity could apply to the individual. Approximated by the individual's lifetime reproductive success, this measure became the keyword of studies linking social and cultural behavior to biological adaptive processes. To be commonly applicable to human populations, it had to be simplified to represent the number of offspring reaching sexual maturity and most existing studies are based on this definition. The current trend, however, seems to consider that, like inbreeding, reproductive success takes its signification in the depth of successive generations. These diverse measures were tested in two traditional populations, Berber and Aymara, and show that finding a satisfactory evaluation of reproductive success is a problem that is still far from a solution. Am. J. Hum. Biol. 15:352–360, 2003. © 2003 Wiley‐Liss, Inc.
Identifying cumulative trauma disorders of the upper extremity in workers' compensation databases
Authors: Zakaria Dianne , Mustard Cam , Robertson James , MacDermid Joy C. , Hartford Kathleen , Clarke Judy , Koval John
Published: April 2003

Background

Impeding the use of workers' compensation databases for surveillance of cumulative trauma disorder of the upper extremity (CTDUE) is the lack of valid and reliable extraction strategies.

Methods

Using the Z795‐96 Coding of Work Injury or Disease Information standard, analgorithm was developed to classify claims as definite, possible, or non‐CTDUE. Reliability was assessed with standardized claim reviews.

Results

Moderate to substantial agreement (Kappa = 0.48, 95% CI 0.42–0.54, n = 328; weighted Kappa = 0.75, 95% CI 0.70–0.80, n = 328) was demonstrated. The algorithm produced relatively homogeneous groups of definite and non‐CTDUE claims but 29.1% of the possible CTDUE claims were categorized as definite CTDUE by claim review. Part of body agreement was almost perfect (Kappa = 0.81–1.00) when determining whether the upper extremity or specific parts of the upper extremity were involved.

Conclusions

The algorithm can be used to estimate the number of CTDUE and extract homogeneous groups of definite and non‐CTDUE claims. Furthermore, certain upper extremity part of body codes can be used to target anatomically defined claims. Am. J. Ind. Med. 43:507–518, 2003. © 2003 Wiley‐Liss, Inc.
The properties of polyvinyl fluoride film
Authors: Simril V. L. , Curry Barbara A.
Published: April 2003

Polyvinyl fluoride can be made into clear and pigmented films in thickness ranging from 0.0005 to 0.004 in. and in both biaxially oriented and essentially unoriented forms. These films are extremely long‐lived outdoors and are strong, tough, flexible, and inert. Useful lives of 10 years and more in Florida exposure have been demonstrated, and it has been shown that there is a linear relation between exposure time and the logarithm of film extensibility in both natural and accelerated weathering. Biaxial orientation of PVF film results in high tensile and impact strength and great resistance to flexural fatigue. Lesser degrees of orientation result in higher tear strength, greater extensibility at higher temperatures, and decreased shrinkage at high temperatures. Both oriented and unoriented films retain a large proportion of their strength properties after 1500 hr. in steam or in 150°C. dry heat. Both are highly resistant to nonoxidizing acids, bases, and solvents. PVF films have high dielectric constants, good dielectric strength, and intermediate electrical resistivity and dissipation factor.
Methyl α‐cyanoacrylate. I. Free‐radical homopolymerization
Authors: Canale A. J. , Goode W. E. , Kinsinger J. B. , Panchak J. R. , Kelso R. L. , Graham R. K.
Published: April 2003

Methyl α‐cyanoacrylate, when suitably inhibited by Lewis acids against anionic polymerization, can be polymerized readily with free‐radical initiators to form hard, clear, high molecular weight polymers. The ratio of kp2/kt is approximately 0.021 at 60°C. if 100% efficiency of initiation by azobisisobutyronitrile is assumed. Acceleration occurs at very low conversion to polymer during bulk polymerizations. The homopolymer is thermally unstable at temperatures only slightly above the glass temperature (estimated to be 165–170°C.). Degradation of the polymer under gamma irradiation is pronounced, only 18 e.v. being required per main‐chain scission.
Crystallinity of siloxane polymers
Authors: Fischer David J.
Published: April 2003

Four homopolymers (dimethyl‐, phenylmethyl‐, diphenyl‐, and trifluoropropylmethylpolysiloxanes) and two copolymer systems (dimethylsiloxane–phenylmethylsiloxane and phenylmethylsiloxane–diphenylsiloxane) have been studied by observing spherulite nucleation, growth, and melting. A characteristic crystallization temperature is proposed which can be considered representative of the equilibrium freezing–melting point. This work isolates the crystallinity characteristics of pure siloxane polymer and copolymer systems.
Stress‐strain testing of rubbers at high rates of elongation
Authors: Dannis Mark L.
Published: April 2003

A high speed stress‐strain apparatus has been constructed to measure the strength and elongation of rubbery materials at extension rates roughly 250 and 550 in./sec. The test sample is stretched by falling weight which catches a protruding lug on the lower jaw of the sample. The weight falls from a magnetic grip at one of two selected stations. The potential energy of the falling weight is large compared to the energy under the stress‐strain curve in order to avoid appreciable slowing of the weight during the period of stretch. The excess energy is dissipated in several kinds of damping mechanisms without damage to other than expendable crash pads. The tensile load on the rubber sample is carried by a stiff‐strain‐gage beam, the output of which is displayed on an oscilloscope for photographic recording. Stress‐strain curves of rubber recorded for stretch rates about 550 in./sec. show evidence of sonic wave pulses in the early portions of the extension cycle. Ultimate tensile and elongation values differ somewhat from values obtained using conventional test machines.
Flexural fatigue testing of polyesters
Authors: Hagerup E.
Published: April 2003

A method is described for evaluating flexural fatigue properties of unsaturated polyesters. With the use of the Sonntag fatigue machine and a modified version of the Prot principle, dynamic parameters and fatigue properties can be readily determined. Testing of castings with no reinforcement reveals two different modes of resin fracture, brittle and plastic. A plastic fracture implies that the resin yields before breaking. Reproducibility of the results is directly related to the type of fracture, ranging from very good for a plastic resin to very poor for a brittle. Close proximity of yield points and endurance limits for plastic resins confirms validity of Prot's method of extrapolating the latter parameter. Incorporation of two layers of glass cloth in positions corresponding to the outermost plies in a laminate shows that failure at the glass–resin interface may be the overriding cause of laminate breakdown. Both plastic and brittle resins become stiffer in the presence of glass, but only the plastic resin is realizing its inherent strength to give a stronger reinforced casting. The brittle resin is, on the other hand, weaker with glass present because of inability to dissipate local stress concentrations at the warpfilling crossovers. The break amplitude is a particularly significant parameter because it is expected to be the same in a normal laminate as in these castings with only the outermost plies present. Additional plies would merely increase stiffness and, correspondingly, the stress to reach amplitude coincident with failure at the outermost plies. Use of relatively thick test bars (0.5 in.) permits insertion of a thermocouple in the neutral plane without affecting dynamic properties. Measurement of the temperature rise during flexing allows assessment of the damping capacity of the glass–resin system, which is of particular importance for resonance fatigue. By this means, three different types of glass–resin systems could be distinguished: (1) weak and high damping (plastic), (2) strong and low damping (brittle), (3) strong and high damping (tough). For a particular resin, the behavior is determined by the basic composition as well as by degree of cure. For well‐cured polyester samples, several links were found between dynamic parameters, such as stiffness, fatigue strength and damping, and basic composition. Distance between crosslinks in the polyester backbone thus appears to have a direct bearing on strength and damping. Such relationships are valuable in that they make possible predictions of the fatigue behavior of a given polyester formulation.
Infrared spectra of stereoregular polymethyl methacrylate
Authors: Nagai H.
Published: April 2003

Stereospecific polymerization of deuterated methyl methacrylates, CH2C(CH3)‐COOCD3, CD2C(CD3)COOCH3, and CD2C(CD3)COOCD3, which were prepared by the acetone–cyanohydrin method, were carried out. From the polarized infrared study of polymethyl methacrylate and its deuterated analogue, the spectra of stereo‐regular polymethyl methacrylates were tentatively assigned in the 4000–400 cm.−1 region. The isotactic polymers are easily crystallized and show intensity variations of bands. These bands originate mainly from the deformation vibrations of the α‐CH3 group, the stretching vibrations of the CCO side chain, and the skeletal stretching vibration coupled with CH2 rocking vibration.
Diffusion of gases in fluorocarbon polymers
Authors: Brandt W. W. , Anysas G. A.
Published: April 2003

The diffusion and solubility coefficients and their temperature coefficients of several gases in fluorocarbon polymers were measured by a spring balance and radiotracer method. The activation energies of small molecule diffusion in polytetrafluoroethylene increase with the diffusate molecular diameter squared. The increase is less than that found in many other typical polymers and this is probably due to pre‐existing holes or channels. The latter are most likely to occur in polymers consisting of stiff chain molecules which have a low packing efficiency. Furthermore, the activation energies are not simply proportional to the cohesive energy density. These findings and the general relation between activation energy and solute molecular size can be explained in terms of the model proposed earlier. The apparent frequency factors in the Arrhenius expression for the diffusion coefficients also are low in comparison to other typical polymers presumably because the diffusate molecules are forced to follow a tortuous path through the polymer. The effect of polymer crystallinity and transitions are discussed briefly. Many molecular motions apparently lead to successful diffusion events, again in agreement with the model mentioned above. A simple and rather unambiguous method to derive activation entropies is reported and the diffusion processes in low and high molecular weight materials have been compared.
Redispersible latex polymer
Authors: Guziak L. F. , Maclay W. N.
Published: April 2003

Latices containing 55 parts of styrene, (45 − X) parts of 2‐ethylhexyl acrylate, and X parts of methacrylic acid, where X > 15, have been shown to yield discontinuous crazed films upon drying. These clear transparent polymer granules upon immersion in water containing a base are peptized to form a reconstituted latex containing spherical particles of the same size as the original latex particles. Inclusion of small amounts of a filming aid in the original or reconstituted latex permits the deposition of continuous polymer films which are rendered water‐resistant by baking. The property of redispersibility in water of transparent flakes of polymer is attributed to limited particle coalescence in the polymer grit. The incorporation of relatively high levels of carboxyl groups in the polymer is essential to the redispersion of the polymer by dilute solutions of base. Ionization of the carboxyl groups on the particle surfaces upon addition of a base gives rise to the sudden development of repulsive Coulombic forces which cause particle separation, after which surface forces are sufficient to restore the semiplastic particles to their original spherical shape. Inability to redisperse the film a second time may be due to polymer plasticization or to the migration of carboxyl groups to the particle interior as a result of coalescence forces.