bluuebunny/crossref_metadata_2025 huggingface dataset:
Timing of menarche among survivors of childhood acute lymphoblastic leukemia: A report from the Childhood Cancer Survivor Study
Authors: Chow Eric J. , Friedman Debra L. , Yasui Yutaka , Whitton John A. , Stovall Marilyn , Robison Leslie L. , Sklar Charles A.
Published: August 2007

Background

The objective of this study was to determine risk factors associated with abnormal timing of menarche among survivors of childhood acute lymphoblastic leukemia (ALL).

Procedure

Self‐reported age of menarche was determined among 949 female ALL survivors participating in the Childhood Cancer Survivor Study (CCSS), a cohort of 5‐year survivors of common pediatric cancers diagnosed from 1970 to 1986, and compared with 1,128 siblings.

Results

The majority of survivors (92%) and siblings (97%) reported menarche between the ages of 10 and 16. Survivors treated with chemotherapy alone, including those exposed to alkylating agents, experienced menarche at a similar rate to siblings. However, compared to chemotherapy alone, cranial radiotherapy was associated with early menarche (age < 10; OR 6.2, 95% CI 2.1, 18.5) while craniospinal radiotherapy was associated with both early (OR 8.6, 95% CI 1.9, 38.6) and late (age > 16; OR 4.8, 95% CI 1.4, 16.7) menarche. There were no differences in effect between <20 and ≥20 Gy radiotherapy doses. In multivariable analysis, younger age at diagnosis was an independent risk factor for early menarche.

Conclusions

Few female childhood ALL survivors experienced menarche outside of the normal range. Alkylating agent exposure was not associated with abnormal timing. However, those exposed to cranial and craniospinal radiotherapy, especially at a young age, should be monitored closely for abnormal timing of menarche. Pediatr Blood Cancer 2008;50:854–858. © 2007 Wiley‐Liss, Inc.
Poly(arylate‐phosphonate) copolymers with deoxybenzoin in the backbone: Synthesis, characterization, and thermal properties
Authors: Ranganathan T. , Ku Bon‐Cheol , Zilberman Joseph , Beaulieu Michael , Farris Richard J. , Coughlin E. Bryan , Emrick Todd
Published: August 2007

Deoxybenzoin‐based copolymers containing various relative ratios of arylate and phosphonate units in the backbone were synthesized by solution polycondensation. These copolymers were characterized by gel permeation chromatography, Fourier Transform infrared spectrometry, and proton, carbon, and phosphorous nuclear magnetic resonance spectroscopy (1H, 13C, and 31P NMR). Pyrolysis combustion flow calorimetry (PCFC) performed on these copolymers revealed their very low heat release capacity, making them attractive for applications in which halogen‐free, low flammability materials are desired. Integration of phosphonate units into the polymer backbone is advantageous for achieving high molecular weight polymers with solution processbility while retaining the low flammability inherent to deoxybenzoin‐based polymers. Char yields greater than 50% and heat release capacities of 40–60 J/g K, were observed for these copolymers by PCFC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4573–4580, 2007
Crystal structure of the flavin reductase component (HpaC) of 4‐hydroxyphenylacetate 3‐monooxygenase from Thermus thermophilus HB8: Structural basis for the flavin affinity
Authors: Kim Seong‐Hoon , Hisano Tamao , Iwasaki Wakana , Ebihara Akio , Miki Kunio
Published: August 2007

The two‐component enzyme, 4‐hydroxyphenylacetate 3‐monooxygenase, catalyzes the conversion of 4‐hydroxyphenylacetate to 3,4‐dihydroxyphenylacetate. In the overall reaction, the oxygenase component (HpaB) introduces a hydroxyl group into the benzene ring of 4‐hydroxyphenylacetate using molecular oxygen and reduced flavin, while the reductase component (HpaC) provides free reduced flavins for HpaB. The crystal structures of HpaC from Thermus thermophilus HB8 in the ligand‐free form, the FAD‐containing form, and the ternary complex with FAD and NAD+ were determined. In the ligand‐free form, two large grooves are present at the dimer interface, and are occupied by water molecules. A structural analysis of HpaC containing FAD revealed that FAD has a low occupancy, indicating that it is not tightly bound to HpaC. This was further confirmed in flavin dissociation experiments, showing that FAD can be released from HpaC. The structure of the ternary complex revealed that FAD and NAD+ are bound in the groove in the extended and folded conformation, respectively. The nicotinamide ring of NAD+ is sandwiched between the adenine ring of NAD+ and the isoalloxazine ring of FAD. The distance between N5 of the isoalloxazine ring and C4 of the nicotinamide ring is about 3.3 Å, sufficient to permit hydride transfer. The structures of these three states are essentially identical, however, the side chains of several residues show small conformational changes, indicating an induced fit upon binding of NADH. Inactivity with respect to NADPH can be explained as instability of the binding of NADPH with the negatively charged 2′‐phosphate group buried inside the complex, as well as a possible repulsive effect by the dipole of helix α1. A comparison of the binding mode of FAD with that in PheA2 from Bacillus thermoglucosidasius A7, which contains FAD as a prosthetic group, reveals remarkable conformational differences in a less conserved loop region (Gly83–Gly94) involved in the binding of the AMP moiety of FAD. These data suggest that variations in the affinities for FAD in the reductases of the two‐component flavin‐diffusible monooxygenase family may be attributed to difference in the interaction between the AMP moiety of FAD and the less conserved loop region which possibly shows structural divergence. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Molecular dynamics simulations of HIV‐1 protease monomer: Assembly of N‐terminus and C‐terminus into β‐sheet in water solution
Authors: Yan Mao‐Cai , Sha Yu , Wang Jian , Xiong Xu‐Qiong , Ren Jin‐Hong , Cheng Mao‐Sheng
Published: August 2007

HIV‐1 protease (HIV‐PR) consists of two identical subunits that are united together through a four‐stranded antiparallel β‐sheet formed of the peptide termini of each monomer. Since the active site exists only in the dimer, a strategy that is attracting more and more attention in inhibitor design and which may overcome the serious drug resistance caused by competitive inhibitors is to block the peptide termini of the monomer, thereby interfering with formation of the active dimer. In the present work, we performed several extensive molecular dynamics (MD) simulations of the HIV‐PR monomer in water to illustrate its solvated conformation and dynamics behavior. We found that the peptide termini usually assembled into β‐sheet after several nanoseconds' simulation, and became much less flexible. This β‐sheet is stabilized by intramolecular interactions and is not easily disaggregated under the present MD simulation conditions. This transformation may be an important transition during the relaxing and equilibrating of the HIV‐PR monomer in aqueous solution, and the terminal β‐sheet may be one of the major conformations of the solvated HIV‐PR monomer termini in water. This work may provide new insights into the dynamics behavior and dimerization mechanism of HIV‐PR, and more significantly, offer a more rational receptor model for the design and discovery of novel dimerization inhibitors than crystalline structures. Proteins 2008. © 2007 Wiley‐Liss, Inc.
A complete library of amino acid alterations at R306 in Streptomyces clavuligerus deacetoxycephalosporin C synthase demonstrates its structural role in the ring‐expansion activity
Authors: Sim Goo Kian , Song Chua Chun , Sim Tiow‐Suan
Published: August 2007

In a previous study, the conserved arginine residue at position 306 of Streptomyces clavuligerus deacetoxycephalsoporin C synthase (scDAOCS), when mutated to leucine, resulted in 191% increase in converting ampicillin to its expanded cephalosporin moiety compared with that of the wild‐type enzyme. However, the role of this residue in eliciting the improved enzymatic activity is not well understood. In this study, probing the molecular basis of amino acid substitutions at position 306 has underscored its importance for engineering various improvements in the ring expansion activity. Structural modeling using SwissPdbViewer revealed that R306 is surrounded by a hydrophobic cleft formed by residues Y184, L186, W297, I298, and V303. Hence, the improved activity achieved by the R306L mutation was probably because of better hydrophobic packing in this region. To evaluate the role of amino acids at position 306 of scDAOCS and its influence on the molecular status of the enzyme at this locality, alteration to 18 other amino acids was done by site‐directed mutagenesis. The effects of each substitution on the enzyme activity were determined by bioassay using penicillin substrates: ampicillin, penicillin G, phenethicillin, and carbenicillin. Results obtained showed a drastic reduction in enzyme activity when R306 was replaced with charged or polar residues, thus emphasizing the importance of hydrophobic packing around this site. The bioassay results also illustrated that apart from leucine, substitutions to nonpolar residues, isoleucine and methionine, were able to improve the ampicillin conversion activity of scDAOCS by 168 and 113% of the wild‐type enzyme activity, respectively. Similar trend of effects from each mutation was also observed for penicillin G, phenethicillin, and carbenicillin conversions. The enhanced enzyme activities were supported by spectrophotometric assay indicating that all these mutants have lower Km values (R306L: 1.09 mM; R306I: 2.64 mM; R306M: 5.68 mM) than the wild‐type enzyme (8.33 mM), resulting in improvement in the enzyme's substrate binding affinity. Hence, this mutational study of amino acids situated at 306 of scDAOCS has provided a better understanding of the significance of specific amino acid residues at this position which can improve its ring‐expansion activity when given a plethora of β‐lactam substrates to generate corresponding, possibly new, cephalosporins. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Membrane‐bound structure and energetics of α‐synuclein
Authors: Mihajlovic Maja , Lazaridis Themis
Published: August 2007

Aggregation and fibrillation of α‐synuclein bound to membranes are believed to be involved in Parkinson's and other neurodegenerative diseases. On SDS micelles, the N‐terminus of α‐synuclein forms two curved helices linked by a short loop. However, its structure on lipid bilayers has not been experimentally resolved. Using MD simulations with an implicit membrane model we show here that, on a planar mixed membrane, the truncated α‐synuclein (residues 1–95) forms a bent helix. Bending of the helix is not due to the protein sequence or membrane binding, but to collective motions of the long helix. The backbone of the helix is ∼2.5 Å above the membrane surface, with some residues partially inserted in the membrane core. The helix periodicity is 11/3 (11 residues complete three full turns) as opposed to 18/5 periodicity of an ideal α‐helix, with hydrophobic residues towards the membrane, negatively charged residues towards the solvent and lysines on the polar/nonpolar interface. A series of threonines, which are characteristic for α‐synuclein and perhaps a phosphorylation site, is also located at the hydrophobic/hydrophilic interface with their side chain often hydrogen bonded to the main‐chain atom. The calculations show that the energy penalty for change in periodicity from the 18/5 to 11/3 on the anionic membrane is overcome by favorable solvation energy. The binding of truncated α‐synuclein to membranes is weak. It prefers anionic membranes but it also binds marginally to a neutral membrane, via its C‐terminus. Dimerization of helical monomers on the mixed membrane is energetically favorable. However, it slightly interferes with membrane binding. This might promote lateral diffusion of the protein on the membrane surface and facilitate assembly of oligomers that precede fibrillation. Proteins 2008. © 2007 Wiley‐Liss, Inc.
The role of Li+, Na+, and K+ in the ligand binding inside the human acetylcholinesterase gorge
Authors: Petraglio Gabriele , Bartolini Manuela , Branduardi Davide , Andrisano Vincenza , Recanatini Maurizio , Gervasio Francesco Luigi , Cavalli Andrea , Parrinello Michele
Published: August 2007

Alkali cations can affect the catalytic efficiency of enzymes. This is particularly true when dealing with enzymes whose substrate bears a formal positive charge. Computational and biochemical approaches have been combined to shed light on the atomic aspects of the role of Li+, Na+, and K+ on human acetylcholinesterase (hAChE) ligand binding. In this respect, molecular dynamics simulations and our recently developed metadynamics method were applied to study the entrance of the three cations in the gorge of hAChE, and their effect on the dynamical motion of a ligand (tetramethylammonium) from the bulk of the solvent into the deep narrow enzyme gorge. Furthermore, in order to support the theoretical results, KM and kcat for the acetylcholine hydrolysis in the presence of the three cations were evaluated by using an approach based on the Ellman's method. The combination of computational and biochemical experiments clearly showed that Li+, Na+, and K+ may influence the ligand binding at the hAChE gorge. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Surface recognition elements of membrane protein oligomerization
Authors: Rath Arianna , Deber Charles M.
Published: August 2007

Although certain membrane proteins are functional as monomeric polypeptides, others must assemble into oligomers to carry out their biological roles. High‐resolution membrane protein structures provide a valuable resource for examining the sequence features that facilitate—or preclude—assembly of membrane protein monomers into multimeric structures. Here we have utilized a data set of 28 high‐resolution α‐helical membrane protein structures comprising 32 nonredundant polypeptides to address this issue. The lipid‐exposed surfaces of membrane proteins that have reached their fully assembled and functional biological units have been compared with those of the individual subunits that build quaternary structures. Though the overall amino acid composition of each set of surfaces is similar, a key distinction—the distribution of small‐xxx‐small motifs—delineates subunits from membrane proteins that have reached a functioning oligomeric state. Quaternary structure formation may therefore be dictated by small‐xxx‐small motifs that are not satisfied by intrachain contacts. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Electrostatic contribution to the thermodynamic and kinetic stability of the homotrimeric coiled coil Lpp‐56: A computational study
Authors: Bjelić Saša , Wieninger Silke , Jelesarov Ilian , Karshikoff Andrey
Published: August 2007

The protein moiety of the Braun's E. coli outer membrane lipoprotein (Lpp‐56) is an attractive object of biophysical investigation in several aspects. It is a homotrimeric, parallel coiled coil, a class of coiled coils whose stability and folding have been studied only occasionally. Lpp‐56 possesses unique structural properties and exhibits extremely low rates of folding and unfolding. It is natural to ask how the specificity of the structure determines the extraordinary physical chemical properties of this protein. Recently, a seemingly controversial data on the stability and unfolding rate of Lpp‐56 have been published (Dragan et al., Biochemistry 2004;43: 14891–14900; Bjelic et al., Biochemistry 2006;45:8931–8939). The unfolding rate constant measured using GdmCl as the denaturing agent, though extremely low, was substantially higher than that obtained on the basis of thermal unfolding. If this large difference arises from the effect of screening of electrostatic interactions induced by GdmCl, electrostatic interactions would appear to be an important factor determining the unusual properties of Lpp‐56. We present here a computational analysis of the electrostatic properties of Lpp‐56 combining molecular dynamics simulations and continuum pK calculations. The pH‐dependence of the unfolding free energy is predicted in good agreement with the experimental data: the change in ΔG between pH 3 and pH 7 is ∼60 kJ mol−1. The results suggest that the difference in the stability of the protein observed using different experimental methods is mainly because of the effect of the reduction of electrostatic interactions when the salt (GdmCl) concentration increases. We also find that the occupancy of the interhelical salt bridges is unusually high. We hypothesize that electrostatic interactions, and the interhelical salt bridges in particular, are an important factor determining the low unfolding rate of Lpp‐56. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Residual structure in disordered peptides and unfolded proteins from multivariate analysis and ab initio simulation of Raman optical activity data
Authors: Zhu Fujiang , Kapitan Josef , Tranter George E. , Pudney Paul D. A. , Isaacs Neil W. , Hecht Lutz , Barron Laurence D.
Published: August 2007

Vibrational Raman optical activity (ROA), measured as a small difference in the intensity of Raman scattering from chiral molecules in right‐ and left‐circularly polarized incident light, or as the intensity of a small circularly polarized component in the scattered light, is a powerful probe of the aqueous solution structure of proteins. The large number of structure‐sensitive bands in protein ROA spectra makes multivariate analysis techniques such as nonlinear mapping (NLM) especially favorable for determining structural relationships between different proteins. We have previously used NLM to map a large dataset of peptide, protein, and virus ROA spectra into a readily visualizable two‐dimensional space in which points close to or distant from each other, respectively, represent similar or dissimilar structures. As well as folded proteins, our dataset contains ROA spectra from many natively unfolded proteins, proteins containing both folded and unfolded domains, denatured partially structured molten globule and reduced protein states, together with folded proteins containing little or no α‐helix or β‐sheet. In this article, the relative positions of these systems in the NLM plot are used to obtain information about any residual structure that they may contain. The striking differences between the structural propensities of proteins that are unfolded in their native states and those that are unfolded due to denaturation may be responsible for their often very different behavior, especially with regard to aggregation. An ab initio simulation of the Raman and ROA spectra of an alanine oligopeptide in the poly(L‐proline) II‐helical conformation confirms previous suggestions that this conformation is a significant structural element in disordered peptides and natively unfolded proteins. The use of ROA to identify and characterize proteins containing significant amounts of unfolded structure will, inter alia, be valuable in structural genomics/proteomics since unfolded sequences often inhibit crystallization. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Ecological network analysis: an application to the evaluation of effects of pesticide use in an agricultural environment
Authors: Andras Peter , Gwyther Robert , Madalinski Agnes A , Lynden Steven J , Andras Alina , Young Malcolm P
Published: August 2007

Ecological network analysis is used to evaluate the impact of pesticide use on ecological systems in the context of agricultural farmland environments. The aim is to provide support for the design of effective and minimally damaging pest control strategies. The ecological network analysis can identify species that are important to the integrity of the ecological network. The methodology can be used to monitor the impact of shifts in terms of types of pesticide used on the ecological system. The authors' intention is to use this methodology to provide supporting evidence for the UK Voluntary Initiative programme aimed at convincing farmers voluntarily to make improved choices in the use of a wide range of pesticides. Copyright © 2007 Society of Chemical Industry
Effect of Ca substitution on transport and magnetic properties of double‐layered manganite La1.2Sr1.8Mn2O7
Authors: Reddy Y. S. , Prashanth Kumar V. , Rawat R. , Banerjee A. , Kistaiah P. , Vishnuvardhan Reddy C.
Published: August 2007

The resistivity, magnetoresistance (MR) and magnetization of double‐layered manganite La1.2Sr1.8–x Cax Mn2O7 (0.0 ≤ x ≤ 0.4) are studied to investigate the effect of substitution of Ca2+ for Sr2+ on the transport and magnetic properties. The resistivity data suggest that Ca doping results in the decrease of insulator‐to‐metal transition temperature, TIM. The conduction mechanism above TIM is found to be of Mott variable range hopping type. The highest MR ratios (Δρ /ρ0) of 73% (H = 1.5 T) and 93% (H = 4 T) are observed for x = 0.3 sample at ∼25 K. The variation of MR with temperature and applied magnetic field is discussed. A secondary transition at T * is observed in all the samples, which may be due to the two‐dimensional short‐range ferromagnetic ordering. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic interaction effects in rare‐earth alloys from 2D‐ACAR experiments
Authors: Biasini M. , Rusz J.
Published: August 2007

Measurement of the two dimensional angular correlation of the electron‐positron annihilation radiation (2D‐ACAR) complemented with ab‐initio calculations can provide decisive information about the character of the f‐electrons in rare earth compounds and are the prerequisite to the study of electron correlations. We provide examples of systems where good approximations of the archetype f‐electron localized and f‐electron itinerant behaviours, apply. i) In the case of the antiferromagnetic heavy fermion and superconductor CeIn3 the multisheet Fermi Surface (FS), reconstructed from our measurements in the paramagnetic phase, agrees closely with the predictions of band structure calculations regarding the Ce 4f electrons as fully localized. ii) On the other hand, our studies of the antiferromagnet actinide based UGa3 in the paramagnetic phase, compared with calculations which include the effects due to the non uniform positron density and the electron‐positron correlations, produce a substantial evidence that an unconstrained 5f‐electron itinerant description applies. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative study of antioxidant properties of wild growing and cultivated Allium species
Authors: Štajner D. , Igić R. , Popović B. M. , Malenčić Dj.
Published: August 2007

Allium species are cultivated for the edible bulb, which is used mainly as flavoring in foods. Besides that, they could prevent tumor promotion and some processes that are associated with free radicals, such as cardiovascular diseases and aging. Therefore, different Allium species, both cultivated (Allium nutans L., A. fistulosum L., A. vineale L., A. pskemense B. Fedtsch, A. schoenoprasum L., A. cepa L. and A. sativum L.) and wild (A. flavum L., A. sphaerocephalum L., A. atroviolaceum Boiss, A. vineale L., A. ursinum L., A. scorodoprasum L., A. roseum L. and A. subhirsutum L.), were investigated in order to evaluate the antioxidant properties of their bulbs. This study reports on the results obtained for the bulb antioxidant enzyme activities (superoxide dismutase, catalase, guaiacol peroxidase, glutathione peroxidase), the quantities of non‐enzymatic plant antioxidants (reduced glutathione and total flavonoids), the contents of soluble proteins, vitamin C, carotenoids, chlorophylls a and b, as well as for the quantities of malonyldialdehyde and •OH and O2•− radicals. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of genotoxic, antigenotoxic and cytotoxic potential of the extract from lichen Cetraria aculeata (Schreb.) Fr. in vitro
Authors: Zeytinoglu H. , Incesu Z. , Tuylu B. Ayaz , Turk A. O. , Barutca B.
Published: August 2007

Naturally occurring compounds can have protective effects towards mutagens and carcinogens as shown by numerous studies. In the present study, the genotoxic/antigenotoxic activities of the extract from lichen Cetraria aculeata (Schreb.) Fr., which has been identified as an antibacterial agent in former studies, were investigated against known mutagens such as 4‐nitro‐o‐phenylenediamine (4‐NPD) and 2‐aminofluorene (2‐AF) in TA98 and TA100 strains of Salmonella typhimurium in the presence or absence of metabolic activity. Further genotoxicity/antigenotoxicity of the extract against mitomycin C for micronucleus formation was also evaluated in human lymphocytes. The cytotoxic effects of the extract on mammalian cells were investigated in three different cell line types by MTT assay. The results obtained show that the extract of C. aculeata has a significant antigenotoxic activity in bacterial systems, but not in mammalian cells and cytotoxic activity in some mammalian cancer cells. However, it was not mutagenic in all systems. The findings suggest that the lichen extract may have a possible therapeutic potential and therefore this must be further investigated by other multiple in vitro bioassays for the development of therapeutic agents. Copyright © 2007 John Wiley & Sons, Ltd.
Treatment of PC‐3 and DU145 prostate cancer cells by prenylflavonoids from hop (Humulus lupulus L.) induces a caspase‐independent form of cell death
Authors: Delmulle L. , Berghe T. Vanden , Keukeleire D. De , Vandenabeele P.
Published: August 2007

Xanthohumol (X), isoxanthohumol (IX), 8‐prenylnaringenin (8PN) and 6‐prenylnaringenin (6PN), prenylflavonoids from hop (Humulus lupulus L.), were investigated for their cytotoxicity and the mechanism by which they exert cell death when incubated with prostate cancer cell lines PC‐3 and DU145. All compounds induced cell death in the absence of caspase‐3 activation and typical apoptotic morphological features. The general pan‐caspase inhibitor zVAD‐fmk could not protect this form of cell death. In addition, the formation of vacuoles was observed in PC‐3 cells treated with IX and 6PN, and in DU145 treated with IX, 8PN and 6PN, which could suggest the induction of autophagy and consequent cell death. The results indicate that hop‐derived prenylflavanones (IX, 8PN, 6PN), but not prenylchalcones (X) induce a caspase‐independent form of cell death, suggested to be autophagy. Therefore, IX, 8PN and 6PN appear to be promising candidates for further investigation in prostate anticancer therapy. Copyright © 2007 John Wiley & Sons, Ltd.
Dosing effects of an antiosteoporosis herbal formula – a preclinical investigation using a rat model
Authors: Sun Ye , Lee Simon Ming Yuen , Wong Yin Mei , Lau Ching Po , Shaw Pang Chui , Qin Ling , Leung Ping Chung , Fung Kwok Pui
Published: August 2007

Herba Epimedii, Fructus Ligustri Lucidi and Fructus Psoraleae are three frequently used Chinese herbs traditionally used for tonifying the ‘kidney system’. They were selected for the present study to formulate an herbal preparation with a weight ratio of 5:4:1 based on their phytochemical, nature, documented treatment efficacy and toxicity. The dosing effects (1 g/day, 0.5 g/day and 0.175 g/day) of the antiosteoporosis function of the water extract of this formula were tested in ovariectomy‐ and calcium deficiency‐induced osteoporotic rats. Eleven weeks of herbal treatment demonstrated a beneficial effect on the preservation of bone mineral density (BMD) at the femur neck in a dose‐dependent manner with the preference for higher dosage. No significant increase in uterus weight was observed in the herbal formula treated rats. In addition, microarray data of kidney tissue revealed that this herbal formula was able to down‐regulate the expression of phase II drug metabolizing enzymes, similar to the effects of estrogens. Copyright © 2007 John Wiley & Sons, Ltd.
Calculation of the paramagnetism of large carbon nanotubes, using a parameter‐independent molecular orbital model
Authors: Alvarez Collado J. R.
Published: August 2007

A previous self‐consistent field molecular orbital method, able to describe systems having a large number of unpaired electrons, n, is reviewed and improved. This method is applied to the study of paramagnetism in large (1,000–16,000 atoms) zigzag carbon nanotubes, represented by their n values. The computational scheme is based on the Hückel neglect differential overlap approach. It is shown that dependence of n on the semiempirical parameters is very small, and so they can be removed from the calculation. Enhancement of the paramagnetism (increase of n), by use of a strong external magnetic field, is also studied. Finally, the dependence of the Fermi one‐electron potential energies and the spin atomic densities on both the parameters and the shape of the nanotubes is analyzed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Comparable Worth and Its Impact on Black Women
Authors: Malveaux Julianne
Published: August 2007

Comparable worth is a subset of affirmative action strategies that deal with all of the terms and conditions of employment including hiring, recruitment, promotion, transfer, and wages. This article describes the comparable worth strategy and its potential impact on black women, black men, and the black community. By viewing the representation of black women in municipal clerical jobs, the author concludes that black women will gain from comparable worth. Because black men are overrepresented in “typically female” jobs, it is further concluded that black males will gain from implementation of comparable worth. Finally, because comparable worth will examine the basis for pay scales, the author concludes that both gender and racial bias may be revealed when job evaluations are examined. This article also views limitations to the comparable worth strategy and distributional concerns of comparable worth.
A Report on the Educational Status of Black Women during the un Decade of Women, 1976-85
Authors: Wilkerson Margaret B.
Published: August 2007

By most statistical indicators, the educational gains made by black women during the past decade are rapidly being eroded: high school completion rates and college enrollment figures are declining, and dropout rates are increasing. The increase in black women earning bachelors and graduate degrees is due almost entirely to their higher participation rates in college. A higher proportion of blacks than whites are below 24 years of age; declining enrollments at a time when the black population is expanding reflects a significant loss. Important areas for policy initiatives include increases in financial aid, a critical factor in college attendance by black women—particularly at the graduate and professional degree levels—improvement in quality of primary and secondary education and counseling, and continuing education programs for teenage mothers.
Black Women and the Job Training Partnership Act
Authors: Harper Harriett
Published: August 2007

Available data show that JTPA has provided some economically disadvantaged black women with employment and training services. Many black women who had suffered employment setbacks or entry problems during the recession that ended in 1982 need assistance in gaining access to the labor market. This is particularly true of young black women. At the same time, it is not clear from available evidence whether single black women who are supporting families alone and who are considered the core group of impoverishment in the black community have been—or, under the present configuration, can be—served adequately by JTPA.
Black Women who Head Families: An Economic Struggle
Authors: Simms Margaret C.
Published: August 2007

Black families headed by women have much lower incomes and higher poverty rates than almost any other type of family. They are disproportionately dependent on welfare and are less likely to receive support from absent fathers. This is a very serious problem for the black community because of the increasing proportion of black families headed by women alone. This article outlines the dimensions of the economic problem and reviews the likely impact of recent policy changes on these families.
General Health Conditions and Medical Insurance Issues concerning Black Women
Authors: Headen Alvin E. , Headen Sandra W.
Published: August 2007

In the last 30 years the health status of black women has improved. However, the likelihood of health problems from complications of pregnancy and childbirth or prolonged illness from combined effects of diabetes, hypertension, and obesity remains. The need for continuity of care for these conditions and the low economic status of black women suggest that current policy shifts away from emphasis on increased access to medical care will adversely affect the health status of black women. Policies to contain health-care costs should therefore be designed to assure appropriate access to needed care for black women and other low-income groups.
Employment Implications of a Changing Health-Care System
Authors: Mckinney Fred
Published: August 2007

The American health-care system has undergone rapid growth and structural change over the past 20 years. Because of the increase in expenditures flowing into the system, total employment in the industry has increased significantly. Along with total employment, the employment of black women has also grown. Unfortunately, however, black women continue to be concentrated in the lowest paying of the health occupations. Efforts to improve the occupational distribution of blacks in general and black women in particular are going to be more difficult in the future because of the dominance of cost containment as the nation's primary health policy goal.
Women and Self-Employment in Urban Tanzania
Authors: Johnson Willene A.
Published: August 2007

This study examines the employment and earnings of self-employed women in urban Tanzania. Most of the empirical evidence comes from a household survey that interviewed 5,543 adults in seven mainland towns during 1971. Although women represent almost 28% of all urban self-employed, they are clustered into a few low-income activities. Women's involvement in household and subsistence production leads them to work fewer hours in market activities, but their lower earnings are mostly due to their restricted access to education and capital.
An Estimation of the Aggregate Educational Production Function for Public Schools in Louisiana
Authors: Andrews Donald R. , Fayissa Bichaka , Tate Uday S.
Published: August 2007

Data at the school district level were used to estimate the relationship between basic skills test scores and various school district, family and community educational inputs. The inputs examined in the regression analysis included expenditures per student, student-teacher ratio, years of teacher's experience, along with other school-related and socioeconomic variables. Expenditures per student are significantly related to basic skills test results in a quadratic manner. Variables measuring family and community structure are shown to be significant to test performance. These results are important for policy-makers who are responsible for the allocation of funds in the education process. A greater reliance on economic incentives is suggested as an alternative to the present system.
Race, Amenities, and Psychic Income
Authors: Kimenyi Mwangi S.
Published: August 2007

Even when there are no racial wage differences between black and white faculty in institutions of higher learning in the Deep South, there are significant racial differences in amenities such that the psychic income of blacks is lower than that of whites. It is demonstrated that black faculty will tend to have higher turnover rates than whites if racial discrepancies in amenities exist. The maintenance of old traditions that affect job satisfaction of blacks acts as a margin to neutralize integration efforts. The assumption that equal pay is equivalent to equal opportunity is challenged.
An Empirical Test of the Cultural Capital Hypothesis
Authors: Johnson James H. , Bienenstock Elisa Jayne , Stoloff Jennifer A.
Published: August 2007

Using data from the Multi-City Survey of Urban Inequality, an exploratory, empirical analysis of the cultural capital hypothesis was conducted. The analyses indicate that, while the types of cultural influences cited by proponents of this thesis clearly have negative effects on employment when viewed in isolation from other factors, they are not significant when statistical controls for human capital variables are incorporated into the model. Our findings suggest the need to invest more resources in the public education system and in efforts to combat racial discrimination in the labor market.
Racial Differences in the Unemployment Response to Structural Changes in Local Labor Markets
Authors: Hyclak Thomas , Stewart James B.
Published: August 2007

This analysis uses establishment-level data on job creation and destruction to examine the unemployment rate responses of black, Hispanic and white workers to shifts in demand across firms and industries during the period 1980-84. Black unemployment rates are significantly more responsive to differences in aggregate demand growth and wage flexibility than are white and Hispanic unemployment rates, and they are also more severely impacted by structural changes in labor demand than are white and Hispanic unemployment rates. Additional research using the measures and focus of the present analysis that cover other time periods can assist in developing a clearer picture of the contemporary dynamics of urban labor markets and can provide guidance for public policy.
Consumer Discrimination, Duopoly, and Black Firm Entry: The Welfare Effect of Subsidies
Authors: Price Gregory N.
Published: August 2007

Consumer discrimination, to the extent that it lowers expected profit for black owned firms, discourages the entry of new black firms. From a social welfare perspective, consumer discrimination may be welfare reducing, since market output is lower than otherwise. If so, a policy intervention that subsidizes new black firms may improve social welfare. This article presents a simple model of duopoly where consumer discrimination exists with uncertainty, and the only cost of production is a “loss of sales” cost. Given the Nash equilibrium, in which a black and white firm must select a price to charge, conditions are derived for which a profit subsidy to a new black firm increases, decreases, or has no effect on social welfare.
Characteristics of Black-Owned Corporations in Atlanta: With Comments on the Smobe Undercount
Authors: Boston Thomas D.
Published: August 2007

Black-owned corporations are only 3 percent of all black-owned businesses in the nation, but account for almost half of all revenue and employment of these businesses. Even though their rate of growth greatly exceeds that of proprietorships and partnerships, very little is known about the characteristics of black-owned corporations. The Survey of Minority-Owned Business Enterprises (SMOBE) is published every five years by the Department of Commerce and is the most comprehensive source of information on black-owned businesses. Yet, most researchers fail to realize that this survey does not include all corporations in its survey universe, but only 1120 S corporations. This study uses primary data collected on 722 of the most successful black-owned businesses in the Atlanta metropolitan area. We analyze the characteristics of black-owned corporations and the human capital attributes of their owners, and we comment on the SMOBE undercount of 1120 subchapter C corporations. We find that in Atlanta, not only do black-owned subchapter C corporations greatly outnumber S corporations, but they also have a much greater financial capacity.
Revisiting the Relationship between Growth and Poverty
Authors: Azam Golam , Redmon Alonzo
Published: August 2007

The purpose of this article is to revisit the relationship between growth and poverty which was widely discussed during the sixties. In view of the renewed reliance on this mechanism during the eighties by the Reagan administration and a concomitant increase in the incidence of poverty, a revisit of the topic is relevant. A regression model similar to the previous studies, but expanded to capture the emerging issues during the eighties is estimated for the period 1964–1987. A simple variable coefficient model to capture the secular decline in the effectiveness of growth to reduce poverty is also estimated.

It is found that over the sample period, growth and transfer payments had significant effects on poverty; but their effects have been diminished by changes in income distribution, family composition, and the decline of the manufacturing sector during the seventies and eighties. Another interesting finding is that the impact of growth on the incidence of poverty is race neutral.
Enterprise Zones: Incentives are not Attracting Minority Firms
Authors: Glover Glenda
Published: August 2007

This study examines the effectiveness of the enterprise zone concept as a tool for economic development, particularly as it relates to increased minority business ownership and minority employment. Two research tests regarding the extent of minority firm participation and minority employment in the enterprise zones, as well as the incentives which were most likely to attract minority firms to the enterprise zones, are presented.

The results suggested that enterprise zones contributed to business development and the creation of several new jobs. However, minority firms were not found to be participating in the program at meaningful levels. It is recommended that the enabling legislation be amended to address these issues.
Attitudes towards Race and Poverty in the Demand for Private Education: The Case of Mississippi
Authors: Conlon John R. , Kimenyi Mwangi S.
Published: August 2007

Most studies of the demand for private education have treated “white flight” as a response to the proportion of the population that is black in a particular area. The present article, by contrast, considers the possibility that this flight may be from poverty rather than race. The article develops an aggregate demand function for private education from which individual behavior may be inferred, and then applies the model to data from Mississippi. The results suggest that prejudice is directed against poor blacks rather than against nonpoor blacks or poor whites.
Factors Affecting the External Debt-Servicing Capacity of African Nations: An Empirical Investigation
Authors: Ngassam Christopher
Published: August 2007

While there have been a vast number of studies and international discussions on developing nations’ debt servicing capacity, not much attention has been focused on the African dimension. This article examines the determinants of debt reschedulings for forty-five African nations over the twelve-year period 1976 to 1987. A logit model of the macroeconomic variables affecting the probability of rescheduling is developed. The findings indicate that debt-service ratio, reserves to imports ratio, debt-service payments to capital inflow ratio, GDP growth rate, rate of domestic inflation, and net government deficit to GDP ratio are important indicators of debt servicing capacity. The overall results, while providing strong support for some of the often-mentioned causes of the African debt crisis, are seen to hold useful possibilities for both the debtor countries and international creditors.
Agricultural Exports and the Agenda for Accelerated Development in Africa
Authors: Egbe Emmanuel Chinyere
Published: August 2007

In this article the translog cost function with non-neutral parameter shifts is used to study the import demand functions of agricultural commodities which African countries export in competition with other developing regions of the world. It is shown that there has been a systematic bias against the import of these commodities from Africa in favor of importing them from other developing regions. It is then argued that these results support the apprehensions of many African leaders regarding the adoption of a policy of agriculture-based, export-led growth to accelerate economic development on the continent.
Interregional Migration of Labor in Ghana, West Africa: Determinants, Consequences and Policy Intervention
Authors: Arthur John A.
Published: August 2007

This article examines the determinants, consequences and policy intervention measures of the movement of labor within Ghana's administrative regions. The study concludes that the economic inequalities brought about by the uneven distribution of development projects in favor of urban areas causes depressed rural economic conditions, thus spurring rural to urban migration. Migration to the urban places of Ghana is therefore caused by individuals and families seeking better economic opportunities to improve the quality of their lives. Secondary determinants are varied, ranging from family obligations to the quest for adventure. The benefits of migration for the rural areas lie mainly in returned migrants’ contributions to the economic development of those areas. Migrants also contribute to the urban areas’ economic development, but their presence in large numbers has caused problems in the housing and in the delivery of social services. Rural development policies and land settlement schemes have been unsuccessful, due mainly to the lack of a comprehensive national development effort.
The Dilemma of Black Banking: Lending Risks Vs. Community Service
Authors: Brimmer Andrew F.
Published: August 2007

Black-owned banks face a serious dilemma: founded primarily to help fill the gap between the demand for and supply of credit to the black community, the more they try to respond positively, the greater is the probability that they will fail. The paradox arises from the exceptional risks these lenders must assume when they extend credit to individuals who suffer from above-average instability of employment and income, or to black-owned businesses, which have high rates of bankruptcy. The failure of Freedom National Bank in November 1990 illustrates the adverse consequences of assuming excessive risks.
An Analysis of Wage Differentials by Gender and Ethnicity in the Public Sector
Authors: Idson Todd L. , Price Hollis F.
Published: August 2007

This study investigates the source of wage differentials between blacks, Hispanics, and whites, and between women and men, in metropolitan Dade County (Florida) government, and draws out the implications of this analysis for affirmative action planning. Our distinctive finding is that the primary factor causing observed wage differentials by ethnicity is the sorting of people across occupational categories. Wage decompositions reveal that for males, 70 percent, 88 percent, and 47 percent of the wage gaps between white and black, white and Hispanic, and Hispanic and black, respectively, are attributable to occupation. For females, the corresponding figures are 56 percent, 58 percent, and 51 percent. When comparing men and women of the same ethnic group, occupational employment patterns are found to be an important factor accounting for lower average female wages, yet within major occupational groups women seem to be receiving higher wages (on average) than men.
Black Americans’ Business Ownership Factors: A Theoretical Perspective
Authors: Ahiarah Sol
Published: August 2007

The black American struggle in the United States continues to occur in the political, cultural and economic spheres with some measure of success. Regarding the economic sphere as the most critical because it is the source of real power in this country, and business ownership as the ultimate manifestation of economic liberation, this article examines black Americans’ business ownership and factors facilitating it.

Defining successful business ownership in terms of: (1) increasing business formations by black Americans, (2) survival/longevity of the formed businesses, (3) their creation of jobs, and, (4) their profitability, this article identifies three factors facilitating it. The facilitating factor types are: (1) individual-specific, (2) group-specific, and (3) environment-consequent. It is suggested that the complex interaction of elements of these factors at any time, most likely determines the proportion of black ownership of American businesses.