bluuebunny/crossref_metadata_2025 huggingface dataset:
Secondary structure and association of melittin during and after solid‐phase synthesis: a Raman and static light scattering study
Authors: Lund Hansen C. , Robert Hansen P. , Callisen T. H. , Bauer R. , Faurskov Nielsen O.
Published: August 2002

The solid‐phase synthesis of melittin, a haemolytic peptide containing 26 amino acid residues, was monitored by near‐infrared Fourier transform Raman spectroscopy. The resin used was Tenta Gel S RAM. The secondary peptide structure was investigated for each step in the synthesis. A random coil secondary structure was the most probable in all cases, and accordingly all steps in the synthesis gave good yields. Melittin cleaved from the resin showed an α‐helix secondary structure in the solid state. Raman spectra were obtained for 10, 5, 4, 2 and 1% (w/w) aqueous solutions. The 1 and 2% solutions showed too weak melittin bands to be able to draw conclusions about the secondary structure. However, the more concentrated solutions evidently showed an α‐helical structure. Simultaneous static light scattering, refractive index measurements and exclusion chromatography on synthetic melittin in 50 mM phosphate (pH 7) and 150 mM NaCl showed the presence of dimers and tetramers in the eluted liquid. No evidence of monomers or trimers was found. Copyright © 2002 John Wiley & Sons, Ltd.
Turning innovation into profit
Authors: Millier Paul , Palmer Roger
Published: August 2002

The generic ‘stage and gate process’ is popularly accepted as a means for managing new product development. It advocates that a development project is divided into a series of pre‐defined decision steps in order to balance investment against perceived market risk and return.

Its use implies a number of assumptions — first that the product can be characterized as having features and customers benefits; and second that the market for such a product is identifiable.

This paper describes a process to assist decision making where these two assumptions do not apply. It provides suggestions to assist in the management and development of innovation and new technology, advocating that a marketing‐based perspective of supply‐led innovation is adopted.

Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of the antioxidant and pro‐oxidant activities of broccoli amino acids with those of common food additives
Authors: Martínez‐Tomé Magdalena , García‐Carmona Francisco , Murcia M Antonia
Published: August 2002

The antioxidant and pro‐oxidant activities of broccoli amino acids were compared with those of common food additives. In decreasing order, the data showed that Asp, SMC, GABA, Glu, Gln, Pro, Phe, Leu, Lys, Arg, Asn, Val, Ile, His, Ser, Gly, Orn and Ala, when dissolved in water at concentrations of 0.5 and 0.05 mM, partially inhibited damage to deoxyribose in the presence of ferric‐EDTA and H2O2. In contrast, Tyr and Thr acted as pro‐oxidants in this system. The amino acids present in broccoli had no hydrogen peroxide‐scavenging effect. When dissolved in water, methanol or ethanol, SMC, Glu, Thr, Gln, Ser, GABA, Pro, Ala, Ile, Phe, Asp, Orn and Tyr inhibited lipid peroxidation. However, Asn, Val, Arg, Leu, Lys, His and Gly were not effective in decreasing peroxidation at concentrations of 0.5 and 0.05 mM. Asp > SMC > Ala > Phe > Hys > Orn > Gln = Ser > Lys > Leu = GABA = Gly > Tyr > Arg = Thr > Val > Asn > Pro > Ile > Glu (p < 0.025) showed scavenging activity towards hypochlorous acid, protecting α1‐antiproteinase against inactivation. In this paper it has been established that some amino acids premixed with propyl gallate increase its hypochlorous acid‐scavenging capacity, while other amino acids have an additive effect with propyl gallate, permitting smaller quantities of propyl gallate to be used as food additives in some products which contain these amino acids.

© 2001 Society of Chemical Industry
Towards the production of pharmaceutical fatty acids in transgenic plants
Authors: Napier Johnathan A , Michaelson Louise V
Published: August 2002

Recent advances in plant molecular biology have facilitated the introduction of novel traits into a range of plant species. It is now possible to modify the fatty acid composition of plant oilseeds, which opens up the possibility of improving the nutritional qualities of plant oils. The fatty acid composition of an oilseed determines its end use and therefore its commercial value. Value can be added to certain crop species by manipulations which would allow production of rare and valuable oils. Genetic engineering also provides novel opportunities for the production of pharmaceutical fatty acids such as γ‐linolenic acid and arachidonic acid which are important for human health and nutrition.

© 2001 Society of Chemical Industry
Cyclin D1 overexpression as a prognostic factor in patients with esophageal carcinoma
Authors: Nagasawa Shigenao , Onda Masahiko , Sasajima Koji , Makino Hiroshi , Yamashita Kiyohiko , Takubo Kaiyo , Miyashita Masao
Published: August 2002

Background and Objectives

Cyclin D1 is known to play important roles in the G1/S check‐point of the cell cycle. We investigated the correlation between cyclin D1 overexpression and clinical characteristics to clarify its prognostic significance in patients with esophageal cancer.

Methods

From 1991 to 1998, cyclin D1 was investigated in esophageal cancers from 86 patients who underwent esophagectomy. Overexpression of cyclin D1 was demonstrated using an immunohistochemical method.

Results

Overexpression of cyclin D1 was found in 23 (26.7%) of 86 cases. Overexpression of cyclin D1 correlated with lymph node metastasis (P = 0.0083) and lymphatic vessel invasion (P = 0.018). Cyclin D1 overexpression may indicate resistance to chemotherapy. The patients with cyclin D1 overexpression had a significantly lower survival rate than those without overexpression (P = 0.013). The multivariate analysis revealed cyclin D1 overexpression to be an important prognostic factor in patients with esophageal cancer.

Conclusions

Immunohistochemical examination of cyclin D1 expression may provide important prognostic information in univariate and multivariate analysis and may be necessary for determining therapeutic strategies for esophageal cancer. J. Surg. Oncol. 2001;78:208–214. © 2001 Wiley‐Liss, Inc.
Trace elements content in serum, normal skin, and scar tissues of keloid and normal scar patients
Authors: Bang Rameshwar L. , Al‐Bader Abdul Latif , Sharma Prem N , Mattapallil Alice Babu , Behbehani Abdulla I. , Dashti Hussein
Published: August 2002

Wound healing is a normal physiological process that occurs after injury. Scars are usually formed, and the nature of the scar depends on the balance between the formed and degraded collagen during healing. A balanced production and degradation of collagen in wound healing results in the formation of a normal scar whereas an imbalance produces what is known as keloid scar. The factors that cause an imbalance are not well identified, although many factors, such as immunity, genetic, ischaemia, hormonal, growth, and nutritional factors, are blamed. This study was undertaken to investigate trace elements level in the serum, normal skin, and scar tissue of patients with normal and keloid scars. Copper (Cu), zinc (Zn), selenium (Se), and manganese (Mn) levels were estimated in 100 (50 with normal scars and the others with keloids) patients. The serum level of Zn was found to be higher in keloid scar patients, and this increase was highly significant (P < 0.0001). The level of Cu was significantly higher (P < 0.0001) in the normal skin and scar tissues of keloid patients. Trace element levels in scar tissues were observed to be lower in comparison to normal skin trace element content in both groups. The significant changes of Zn in serum and Cu in skin and scar tissues of keloid patients as noted in this study may suggest their role in the regulation of behavior of scar formation in wound healing. J. Trace Elem. Exp. Med. 15:57–66, 2002. © 2002 Wiley‐Liss, Inc.
Kinetics of the cyclopentadiene decay and the recombination of cyclopentadienyl radicals with H‐atoms: Enthalpy of formation of the cyclopentadienyl radical
Authors: Roy K. , Braun‐Unkhoff M. , Frank P. , Just Th.
Published: August 2002

The recombination of c‐C5H5 with H‐atoms has been studied behind reflected shock waves. The obtained rate coefficients are almost independent of temperature and were found to be krec = 2.6 × 1014 cm3 mol−1 s−1 for pressures around 2 bar in the temperature range between 1150 and 1500 K. Together with rate coefficients for the dissociation, obtained in an earlier work (Roy et al., Proc Combust Inst 1998, 27, 329–336) at pressures and temperatures close to those applied in the present work, we calculated equilibrium constants Kc(T) for C5H6 ⇌ c‐C5H5 + H. A “third law” analysis was performed. Data for the enthalpy of formation of cyclopentadienyl DHf,0 = 65.4 ± 1 kcal mol−1 and DHf,298 = 62.5 ± 1 kcal mol−1 were derived, respectively. The analysis was based upon new results on the entropy of cyclopentadienyl, recently calculated by Kiefer et al. (J phy chem, in press). Finally, our measured data were subjected to a fall‐off analysis. The simulation turned out very satisfactorily. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 821–833, 2001
Experimental and modeling study of the oxidation of 1‐butyne and 2‐butyne
Authors: Belmekki N. , Glaude P. A. , Da Costa I. , Fournet R. , Battin‐Leclerc F.
Published: August 2002

Ignition delays were measured behind shock waves in the cases of hydrocarbon–oxygen–argon mixtures containing 1‐butyne or 2‐butyne (1 or 2% of hydrocarbons for equivalence ratios from 0.5 to 2). Reflected shock waves permitted to obtain temperatures from 1100 to 1600 K and pressures from 6.3 to 9.1 atm.

A detailed mechanism of the reactions of 1‐butyne and 2‐butyne has been explained in the line of the mechanism developed previously for the reaction of C3–C4 unsaturated hydrocarbons (propyne, allene, 1,3‐butadiene) [Int J chem Kin 1999, 31, 361]. It is based on the most recent kinetic data values published in the literature and is consistent with thermochemistry.

This mechanism has been validated by comparing the results of our simulations to the experimental results obtained for ignition delays in our shock tube and to measurements of species obtained during thermal decomposition [Int J Chem Kin 1995, 27, 321; J Phys Chem 1993, 97, 10977]. The main reaction pathways have been derived from flow‐rate and sensitivity analyses. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 172–183, 2002; DOI 10.1002/kin.10035
Catalytic hydrolysis of p‐nitrophenyl picolinate by copper(II) and zinc(II) complexes of N‐(2‐deoxy‐β‐D‐glucopyranosyl‐2‐salicylaldimino)
Authors: Yan Xiang , Zeng Xiancheng , Cheng Siqing , Li Yantuan , Xie Jiaqing
Published: August 2002

D‐glucosamine Schiff base N‐(2‐deoxy‐β‐D‐glucopyranosyl‐2‐salicylaldimino) and its Cu(II) and Zn(II) complexes were synthesized and characterized. The hydrolysis of p‐nitrophenyl picolinate (PNPP) catalyzed by ligand and complexes was investigated kinetically by observing the rates of the release of p‐nitrophenol in the aqueous buffers at 25°C and different pHs. The scheme for reaction acting mode involving a ternary complex composed of ligand, metal ion, and substrate was established and the reaction mechanisms were discussed by metal–hydroxyl and Lewis acid mechanisms. The experimental results indicated that the complexes, especially the Cu(II) complex, efficiently catalyzed the hydrolysis of PNPP. The catalytic reactivity of the Zn(II) complex was much smaller than the Cu(II) complex. The rate constant kN showing the catalytic reactivity of the Cu(II) complex was determined to be 0.299 s−1 (at pH 8.02) in the buffer. The pKa of hydroxyl group of the ternary complex was determined to be 7.86 for the Cu(II) complex. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 345–350, 2002
Kinetics and mechanism for the H‐for‐X exchange process in the H + C6H5X reactions: A computational study
Authors: Tokmakov I. V. , Lin M. C.
Published: August 2002

The addition of H atoms to benzene and toluene and subsequent transformations were investigated using high level ab initio and density functional theory methods. Molecular structures and vibrational frequencies calculated at the B3LYP/6‐311++G(d,p) level of theory were used in combination with adjusted G2M energetic parameters for RRKM rate constant calculations. Standard heats of formation for cyclohexadienyl and cyclohexadienyl, 6‐methyl radicals calculated through isodesmic reactions amounted to 49.5 ± 2 and 42.9 ± 3 kcal/mol, respectively. Rate constants for various elementary reactions involved in the H‐for‐X exchange (X = D, CH3) were calculated and closely correlated with the available experimental kinetic data. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 633–653, 2001
Molecular hydrogen elimination from 2,5‐dihydrofuran, 2,3‐dihydrofuran, and 2‐methyl‐2,5‐dihydrofuran: Quantum chemical and kinetics calculations
Authors: Dubnikova Faina , Lifshitz Assa
Published: August 2002

Density Function Theory calculations were carried out to evaluate the potential energy surfaces of H2 elimination from 2,5‐dihydrofuran, 2,3‐dihydrofuran, and 2‐methyl‐2,5‐dihydrofuran. The structure and energetics of the reactants, products, and transition states on the surfaces for all the three systems were determined and unimolecular rate constants for the H2 elimination were calculated from transition state theory. The potential energy surfaces in 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran have each closed shell, 6‐center transition state. The transition state for H2 elimination from 2,3‐dihydrofuran proceeds via two different pathways, both have barriers that are considerably higher than the barriers for H2 elimination from 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran. One pathway proceeds via a 4‐center transition state and one through a carbene intermediate. In all the cases the transition state leads to the formation of a H2‐furan complex toward a complete separation to H2 and furan. The calculated rate constants for 2,5‐dihydrofuran and 2‐methyl‐2,5‐dihydrofuran are in excellent agreement with the experimental observations. Owing to the very high barriers, the process in 2,3‐dihydrofuran cannot compete with other reaction channels, such as isomerizations, and cannot be observed experimentally. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 685–697, 2001
Knowledge management in small firms
Authors: Sparrow John
Published: August 2002

This paper discusses features of small firms that combine to constitute a different milieu for knowledge management. It reports upon work conducted with many small firms and presents a model of considerations and phases in knowledge management projects in small‐firm settings. Copyright © 2001 John Wiley & Sons, Ltd.
Dealing with soil variability: some insights from land degradation research in central Spain
Authors: Fitzjohn C. , Ternan J. L. , Williams A. G. , Perez‐Gonzalez A. , de Alba S.
Published: August 2002

Soil variability is often seen as problematic in land degradation studies in terms of sampling effort, data interpretation and for the extrapolation of results to other areas or time periods. Examples are given from land degradation research undertaken in central Spain which demonstrate some of these problems associated with soil variability. Geostatistics is presented as a useful tool for quantifying soil variability and in particular the variogram for interpreting and understanding spatial patterns. Soil variability is also seen to complicate the issues surrounding management strategies and makes monospecific management strategies less likely to be successful. In recent years several studies have suggested that variability in soil properties and vegetation cover may reduce the risk of land degradation by minimizing the spatial extent of runoff and erosion. These studies suggest that increasing soil variability may prove to be an effective strategy for reducing the runoff and erosion risk. This paper discusses these ideas and highlights the importance of increasing thresholds above which runoff and erosion occurs for the success of such strategies. This in particular applies to many semiarid environments where thresholds are deemed to be extremely low. Finally, these concepts are placed in the context of scale where soil variability may be viewed as existing at a multitude of nested levels varying from the micro‐ to the macro‐scale. Copyright © 2002 John Wiley & Sons, Ltd.
Propylene glycol as a contrasting agent for optical coherence tomography to image gastrointestinal tissues
Authors: Wang Ruikang K. , Elder James B.
Published: August 2002

Background and Objective

Optical coherence tomography (OCT) is a recently developed imaging technique that has the potential to advance the early diagnosis of diseases in the human gastrointestinal (GI) tract. How ever, the high scattering nature of GI tissue limits its imaging depth and contrast. For more effective diagnosis using OCT, a concurrent improvement of imaging depth and contrast is, therefore, needed. In this work, we investigate the administration of chemical agents to the tissue as a means of improving the capability of OCT imaging of clinically relevant microstructures of the GI tract.

Study Design/Materials and Methods

Normal human GI tissues, including stomach and oesophagus were obtained from patients in hospital, and were imaged with OCT within 0.5–2 hours of removal. Immediately after the first imaging of the specimens with OCT, about 0.5 ml of 80% propylene glycol solution was applied onto the tissue surface and the tissue allowed to absorb the chemical compounds for 20 minutes. Another image was then taken at the same position. The specimens were then embedded and stained in preparation for histologic evaluation. Co‐registration of the images obtained using OCT before and after the topical application of the propylene glycol solution, and standard histopathologic processing provided basis for comparison.

Results

More detailed micro‐structures, including the basal layer position and the cellular composition of the mucosal layer of GI tract tissues were observed after the topical application of propylene glycol solution, while these structures were not resolvable in the conventional OCT images.

Conclusions

Propylene glycol could be used as a contrasting agent for OCT imaging of human GI tract tissues, allowing an increased capability of OCT for rapid clinical diagnosis in vivo. Lasers Surg. Med. 30:201‐208, 2002. © 2002 Wiley‐Liss, Inc.
Epigenetic silencing of PEG3 gene expression in human glioma cell lines*
Authors: Maegawa Shinji , Yoshioka Hirotaka , Itaba Noriko , Kubota Norika , Nishihara Shigeki , Shirayoshi Yasuaki , Nanba Eiji , Oshimura Mitsuo
Published: August 2002

Genomic imprinting, the phenomenon in which alleles of genes are expressed differentially depending on their parental origins, has important consequences for mammalian development, and disturbance of normal imprinting leads to abnormal embryogenesis and some inherited diseases and is also associated with various cancers. In the context of screening for novel imprinted genes on human chromosome 19q13.4 with mouse A9 hybrids, we identified a maternal allele–specific methylated CpG island in exon 1 of paternally expressed imprinted gene 3 (PEG3), a gene that exhibits paternal allele–specific expression. Because PEG3 expression is downregulated in some gliomas and glioma cell lines, despite high‐level expression in normal brain tissues, we investigated whether the loss of PEG3 expression is related to epigenetic modifications involving DNA methylation. We found monoallelic expression of PEG3 in all normal brain tissues examined and five of nine glioma cell lines that had both unmethylated and methylated alleles; the remaining four glioma cell lines exhibited gain of imprinting with hypermethylated alleles. In addition, treatment of glioma cell lines with the DNA demethylating agent 5‐aza‐2′‐deoxycytidine reversed the silencing of PEG3 biallelically. In this article, we report that the epigenetic silencing of PEG3 expression in glioma cell lines depends on aberrant DNA methylation of an exonic CpG island, suggesting that PEG3 contributes to glioma carcinogenesis in certain cases. © 2001 Wiley‐Liss, Inc.
Regulation of cellular invasion and matrix metalloproteinase activity in HepG2 cell by connexin 26 transfection
Authors: Yano Tomohiro , Yamasaki Hiroshi
Published: August 2002

We previously reported that connexin (Cx) 26 expression is involved in negative growth control of HepG2 cells established from a human hepatoma. We also found that induction of E‐cadherin and subsequent formation of a cell adhesion complex were induced in HepG2 cells by C × 26 expression. To examine the exact role of C × 26‐induced E‐cadherin junctions in regulating appearance of malignant phenotypes of HepG2 cells, we expressed a C × 26 antisense oligodeoxynucleotide (AS‐ODN) in an established HepG2 cell clone that has stable expression of C × 26 genes. We investigated changes in the expression of E‐cadherin, the localization of β‐catenin, and some malignant phenotypes of HepG2 clone after the suppression of C × 26 expression by AS‐ODN treatment. The AS‐ODN treatment prevented the expression of C × 26 and E‐cadherin, and the localization of β‐catenin was changed from cytoplasmic membrane to the cytoplasm. In parallel, a morphological change from a monolayer of polygonal cells to multilayered colonies was induced by the treatment, indicating a change of a malignant phenotype of HepG2 cells. The activity of matrix metalloproteinase 9 (MMP‐9) was elevated by the AS‐ODN treatment. A concomitant increase in invasiveness of the C × 26‐expressing cells by the treatment was also observed in an in vitro assay with Matrigel matrix. These results suggest that the induction of E‐cadherin and formation of the cell adhesion complex by C × 26 expression contribute to the reversal of some malignant phenotypes of HepG2 cells. Furthermore, the C × 26‐dependent expression of E‐cadherin leads to reduction of the invasiveness of the cells through suppression of MMP‐9 activity. © 2001 Wiley‐Liss, Inc.
Frequent loss of imprinting of IGF2 and MEST in lung adenocarcinoma
Authors: Kohda Masakazu , Hoshiya Hidetoshi , Katoh Motonobu , Tanaka Isao , Masuda Ryo , Takemura Tamiko , Fujiwara Mutsunori , Oshimura Mitsuo
Published: August 2002

Genomic imprinting is a parental origin–specific chromosomal modification that causes differential expression of maternal and paternal alleles of a gene. Accumulating evidence suggests that deregulation of imprinted genes, including loss of imprinting (LOI), plays a role in oncogenesis. In the present study, we investigated allelic expression of six imprinted genes in human lung adenocarcinomas as well as in matched normal lung tissue. Informative cases showing heterozygosity for the gene of interest were selected from 35 patients. LOI of the insulin‐like growth factor 2 gene (IGF2) and mesoderm‐specific transcript (MEST, also known as paternally expressed gene 1) was noted in 47% (seven of 15) and 85% (11 of 13) of informative cases, respectively. Monoallelic expression was maintained in all the matched normal tissues examined. LOI of IGF2 was seen more frequently in moderately to poorly differentiated adenocarcinomas. In contrast, H19, small nuclear ribonucleoprotein–associated polypeptide N gene (SNRPN), necdin gene (NDN), and long QT intronic transcript 1 (LIT1) exhibited consistent monoallelic expression in all the informative samples. These findings indicated that independent deregulation took place in imprinted genes and suggested that aberrant imprinting of IGF2 and MEST was involved in the development of lung adenocarcinoma. © 2001 Wiley‐Liss, Inc.
Vertical externality and strategic delegation
Authors: Park Eun‐Soo
Published: August 2002

This paper examines the effects of vertical externality generated by the upstream monopoly on the incentives that owners of competing downstream firms give their managers. It is shown that the introduction of the upstream monopoly may have significant effects on the incentive schemes for the downstream firms' managers. In particular, it is shown that in equilibrium, each owner obtains the simple Nash equilibrium outcome regardless of the mode of competition (quantity or price) in the downstream market. Copyright © 2002 John Wiley & Sons, Ltd.
Dopa‐responsive parkinsonism secondary to right temporal lobe haemorrahage
Authors: Ling Monica J. , Aggarwal Arun , Morris John G.L.
Published: August 2002

A 46‐year‐old man developed a symmetrical parkinsonian syndrome 7 weeks after large right temporal intracerebral haemorrhage resulting from a ruptured arteriovenous malformation. His signs included bradykinesia, rigidity, start hesitation, and poor postural reflexes, without a resting tremor. He also had signs of a Parinaud's syndrome. Computed tomography and magnetic resonance imaging of the brain demonstrated changes in the right temporal lobe associated with the haemorrhage but no abnormality of the basal ganglia or midbrain. Levodopa therapy produced a dramatic improvement within a few days of commencement. We postulate that the parkinsonism resulted from midbrain compression secondary to transtentorial herniation. Although parkinsonism is a rare complication of lobar intracerebral haemorrhage, it is important to recognise as it may be potentially treatable. © 2002 Movemement Disorder Society.
Complex movement disorders following bilateral paramedian thalamic and bilateral cerebellar infarcts
Authors: Tan E.K. , Chan L.‐L. , Auchus A.P.
Published: August 2002

Complex movement disorders (CMD; including tremor, dystonias, choreoatheosis, and myoclonus) following infarcts in the posterior and posterolateral thalamic nuclei have been reported. This case of a 59‐year‐old man who developed CMD following bilateral paramedian and bilateral cerebellar infarcts illustrates the lack of anatomic specificity and the diverse pathophysiology which may underlie CMD. © 2001 Movement Disorder Society.
Observability and stabilization of the vibrating string equipped with bouncing point sensors and actuators
Authors: Khapalov A. Y.
Published: August 2002

The issues of observability and stabilization are analysed for a vibrating string equipped, respectively, either with a point sensor measuring its displacement or a vertical tie‐down viscous damper. It is well known that the aforementioned properties hold for the stationary devices of these types only when they are placed at the ‘irrational points’ of the string. The latter creates obvious difficulties in applications. In this article we discuss how mobile point sensors and dampers, bouncing in a rather simple fashion between any two points on the string, can be employed instead in a more ‘feasible and robust’ way. Copyright © 2001 John Wiley & Sons, Ltd.
Mathematical analysis of some new Reynolds‐rod elastohydrodynamic models
Authors: Bayada G. , Cid B. , Vázquez C.
Published: August 2002

In this paper, some new elastohydrodynamic Reynolds‐rod models are posed to obtain the existence of solution (the lubricant pressure and the elastic rod displacement). More precisely, a sign restriction on fluid pressure for cavitation modelling and different unilateral conditions on the rod displacement associated with a rigid structure coating are formulated in terms of coupled variational inequalities. The particular hinged or clamped boundary conditions on the rod displacement require different techniques to prove the existence of solution. Besides nearly linear coupled problems, two non‐linear rod problems including curvature effects are analysed. Mainly, regularity results and L∞ estimates for the solution of variational inequalities and fixed‐point theorems lead to the existence results for the various coupled models. Copyright © 2001 John Wiley & Sons, Ltd.
Infinitely many stationary solutions for a simple climate model via a shooting method
Authors: Díaz J. I. , Tello L.
Published: August 2002

In this paper, we study the number of steady solutions of a non‐linear model arising in Climatology. By applying a shooting method we show the existence of infinitely many steady solutions for some values of a parameter (the solar constant). This method allows us to determine how many times a solution attains the critical temperature (−10°C) at which the coalbedo is assumed to be discontinuous. Copyright © 2002 John Wiley & Sons, Ltd.
A combination of time‐domain versions of PO and PTD with the FDTD method to evaluate human exposure to an electromagnetic field in an urban environment
Authors: Nonídez L. , Martínez‐Búrdalo M. , Martín A. , Villar R.
Published: August 2002

In this work, a combination of the physical optics in the time domain (TDPO) method and a time‐domain version of the equivalent currents of the physical theory of diffraction (TDPTD) with the finite‐difference time‐domain method (FDTD) is presented in order to compute scattered fields by flat plates. The technique is applied for calculating the energy absorbed by a human head exposed to an electromagnetic field in the presence of a reflecting wall. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 371–374, 2001.
Microwave holographic 3‐D rendering system using a reduced‐size planar array antenna
Authors: Elsadek Hala , Eldeeb Hesham , De‐Flaviis Franco , Jofre Luis , Abdallah Esmat , Hashish Essam
Published: August 2002

A compact rendering system for establishing a three‐dimensional (3‐D) pointer is possible by combining microwave holography with microstrip antenna arrays to enter 3‐D coordinates of a point in space into computer memory. To obtain the reduction in system size, new solutions are proposed in both the holographic reconstruction algorithms and the receiving planar array antenna. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 397–402, 2001.
Green's functions in a PC–PPWG structure
Authors: Caloz Christophe
Published: August 2002

The phased‐array method (PAM), recently introduced to compute Green's functions in infinite photonic crystals (PCs), is extended to the problem of a parallel‐plate waveguide (PPWG) structure loaded by a 2‐D PC. Numerical results show that the final Green's function exhibits a standing‐wave behavior and a high confinement of energy near the source, which emphasize the filtering effect of the photonic bandgap (PBG). Other characteristics of the Green's function are also discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 405–408, 2001.
Resonant contrawound toroidal helix antenna
Authors: Hansen R. C.
Published: August 2002

The resonant CWTHA is examined via a moment‐method simulation. The results show a very high impedance at first resonance with a narrow bandwidth and low efficiency. At second resonance, the resistance is less than an ohm, the reactance is zero, and again, the bandwidth is narrow. The azimuth patterns are not omnidirectional, but may have a dip of 10 dB or more. The simulation shows a loop‐mode cancellation of at least 140 dB. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 408–410, 2001.
A compact dual‐band microstrip patch antenna suitable for DCS/GPS operations
Authors: Wu Jian‐Yi , Row Jeen‐Sheen , Wong Kin‐Lu
Published: August 2002

A new integrated structure of a two‐element microstrip patch antenna with two feeds for DCS/GPS dual‐band operations is proposed. The radiating element for DCS (1710–1880 MHz) operation is a broadband low‐profile cylindrical monopole top loaded with a shorted square patch, which gives a linearly polarized conical‐pattern radiation. The second radiating element is a square‐ring microstrip patch with truncated corners for GPS operation at 1575 GHz, which provides circularly polarized broadside radiation patterns. The two radiating elements are integrated in the proposed antenna to have a compact structure. The proposed antenna meets the bandwidth requirements of DCS and GPS systems, and is suitable for mounting on a vehicle. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 410–412,
Band‐selective extraction of resonant frequencies in high‐Q resonators
Authors: Haala Jens , Zhang Ying , von Hagen Jürgen , Wiesbeck Werner
Published: August 2002

The efficient computation of intrinsic frequencies of resonators is presented by an FDTD computation using a new excitation function and a subsequent application of Prony's method. For an accurate extraction of the frequencies, the excitation function must be rather short in the time domain, as well as having a well‐defined frequency content. A sinc‐type excitation function allows very short simulation times, as well as convenient computation near the Courant limit. The sampling of Prony's method starts after the excitation has decayed, a point in time well defined with the new excitation. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 438–441, 2001.
An integrated probe for phaseless plane‐polar near‐field measurements
Authors: Costanzo Sandra , Di Massa Giuseppe
Published: August 2002

The use of an integrated probe performing phaseless near‐field measurements on a plane‐polar scanning geometry is presented. A significant reduction in the acquisition time as well as in the size of the measurement facility is obtained. A uniformly spaced array of dipoles is chosen as test antenna to validate the proposed method. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 293–295, 2001.
J‐IMPEACH‐MBC: a new concatenated NMR experiment for F1 scalable, J‐resolved HMBC
Authors: Williamson R. Thomas , Marquez Brian L. , Gerwick William H. , Martin Gary E. , Krishnamurthy V. V.
Published: August 2002

A new and improved NMR experiment for F1 scalable, J‐Resolved HMBC is presented. This experiment, called J‐IMPEACH‐MBC, utilizes a minimum number of 180° pulses to preserve maximum signal‐to‐noise ratio and provides a variable scaling factor (N) that can be used to scale the heteronuclear couplings in F1. It should prove to be useful for the determination of relative stereochemistry and other structural problems. In addition, a description of the advantages of the J‐IMPEACH‐MBC compared with the J‐Resolved HMBC‐2 is presented. The method is exemplified with strychnine. Copyright © 2001 John Wiley & Sons, Ltd.
Propeller rotation of aryl groups in triarylsilanes and triarylstannanes
Authors: Lambert Joseph B. , Lin Lijun
Published: August 2002

Rotation of aryl groups was studied in eight systems with the general structure Ar3MX by changes in lineshapes as a function of temperature. Steric constraints were varied at each of the structural components (Ar, M, X). The barrier to rotation decreased as the central atom was changed from carbon to silicon to tin. When the substituent X was large (allyl or Cl), buttressing by the meta methyls in duryl raised the barrier. For X = H, however, buttressing decreased the barrier. Copyright © 2001 John Wiley & Sons, Ltd.
Full term development of rabbit oocytes fertilized by Intracytoplasmic sperm injection*
Authors: Deng Manqi , Yang Xiangzhong (Jerry)
Published: August 2002

Intracytoplasmic sperm injection (ICSI) has been applied successfully in the treatment of male infertility in humans and in fertilization research in mice. However, the technique has had limited success in producing offspring in other species including the rabbit. The aim of this research was to test the in vitro and in vivo developmental of rabbit oocytes after ICSI. Sperm used for ICSI were collected from mature Dutch Belted buck and washed 2–3 times with PBS + 0.1% polyvinyl alcohol (PVA) and then mixed with 10% polyvinyl pyrrolidone (PVP) prior to microinjection. Oocytes were collected from superovulated does 14–15 hr after hCG injection and were fertilized by microinjection of a single sperm into the ooplasm of each oocyte without additional activation treatment. After ICSI, the presumed zygotes were either cultured in KSOM + 0.3% BSA for 4 days or transferred into oviducts of recipient does at the pronuclear or 2‐cell stage. A high percentage of fertilization (78%, n = 114) and blastocyst development (39%) was obtained after ICSI. Control oocytes, receiving a sham injection, exhibited a lower activation rate (31%, n = 51) and were unable to develop to the blastocyst stage, suggesting that the blastocysts developed following ICSI were derived from successful fertilization rather than parthenogenetic development. A total of 113 embryos were transferred to six recipient does. Two recipients became pregnant and delivered seven live young. Our results demonstrated that rabbit oocytes can be successfully fertilized and activated by ICSI and can result in the birth of live offspring. Mol. Reprod. Dev. 59:38–43, 2001. © 2001 Wiley‐Liss, Inc.
Nuclear and microtubule reorganization in nuclear‐transferred bovine embryos
Authors: Shin Mi‐Ra , Park Sang‐Wook , Shim Hosup , Kim Nam‐Hyung
Published: August 2002

We studied the nuclear and microtubule dynamics in nonactivated and pre‐activated chromatin‐removed oocytes following transfer of nuclei from bovine fibroblast cells. Immediately after fusion between membranes of oocytes and fibroblasts, a microtubule aster containing a γ‐tubulin spot was seen near the transferred nucleus in most oocytes regardless of activation conditions. Most fibroblast nuclei transferred into nonactivated oocytes underwent premature chromosome condensation (PCC) and divided into two masses of chromosomes. In contrast, fibroblast nuclei in pre‐activated oocytes rarely underwent PCC, but formed a swelled pronuclear‐like structure. Under nonactivation condition, microtubular spindles surrounded condensed chromosomes during the division of two nuclear structures. Gamma‐tubulins were detected in the vicinity of condensed chromosomes, suggesting transient spindle formation. Two pronuclear‐like structures near the microtubular aster containing γ‐tubulin spot(s) later formed a syngamy‐like nuclear structure. While 20% of reconstructed oocytes under nonactivated conditions developed to morulae and blastocysts, only 4% of reconstructed oocytes under pre‐activated conditions developed to morulae and blastocysts. These results suggest introduction of a foreign centrosome during somatic cell nuclear transfer, which probably plays a role in nuclear remodeling and subsequent development. Mol. Reprod. Dev. 62: 74‐82, 2002. © 2002 Wiley‐Liss, Inc.
Evolution of octopod sperm II: Comparison of acrosomal morphogenesis in Eledone and Octopus
Authors: Ribes Enric , Gimenez‐Bonafé Pepita , Zamora Maria J. , Gonzalez Angel , Kasinsky Harold , Chiva Manel
Published: August 2002

The first stages of acrosome development during Eledone cirrhosa spermiogenesis are similar to that in Octopus vulgaris, and comprise the initial elongation of both organelles. However, the acrosome in E. cirrhosa does not continue its elongation as it does in O. vulgaris. Instead, its length remains fixed and it undergoes a process of helicoidization that includes the entire organelle. In each spermatid, helicoidization of the E. cirrhosa acrosome occurs simultaneously with helicoidization of the nucleus. The acrosome is associated with special structures that probably are involved in the helical torsion of the organelle. We propose a hypothesis to explain the evolutionary relationship between the acrosomes of O. vulgaris and E. cirrhosa, particularly as it is influenced by nucleomorphogenesis and microtubular contraction. Mol. Reprod. Dev. 62: 363–367, 2002. © 2002 Wiley‐Liss, Inc.
Sperm nuclear halos can transform into normal chromosomes after injection into oocytes
Authors: Mohar Isaac , Szczygiel Monika A. , Yanagimachi Ryuzo , Ward W. Steven
Published: August 2002

Mouse sperm nuclei extracted with an ionic detergent and 2 M NaCl retain their overall morphology, but upon subsequent reduction of the protamine disulfides they lose all elements of chromatin structure except the organization of DNA into loop that are anchored to the nuclear matrix. These DNA loops appear as a halo surrounding the nuclear matrix, and nuclei extracted in this manner are, therefore, called nuclear halos. Here, we report that sperm nuclear halos injected into oocytes can form pronuclei, then transform into chromosomes with normal morphology. This suggests that sperm nuclear halos retain all the information necessary for normal chromosomal organization, and that micromanipulation of these extracted sperm nuclei can be accomplished without major DNA damage. Mol. Reprod. Dev. 62: 416–420, 2002. © 2002 Wiley‐Liss, Inc.
In vivo analysis of the regulation of the anti‐Müllerian hormone, as a marker of Sertoli cell differentiation during testicular development, reveals a multi‐step process
Authors: Beau Charlotte , Vivian Nigel , Münsterberg Andrea , Dresser David W. , Lovell‐Badge Robin , Guerrier Daniel
Published: August 2002

Anti‐Müllerian hormone (AMH) is a member of the TGF‐β family which elicits its main action during male sex differentiation. This hormone is probably the most convenient marker of Sertoli cell differentiation and maturation throughout testicular development. Studying AMH gene regulation may thus be one way of identifying effectors of Sertoli cell differentiation. To this end we first tried to locate and then to characterise DNA elements responsible for in vivo transcriptional control of AMH expression. We obtained transgenic mice expressing a reporter gene (LacZ), under control of various putative AMH regulatory sequences. Analysis of transgenic animals revealed that activation of the AMH gene probably requires a two‐step regulatory process. The first step corresponds to the initial activation of the AMH gene occurring at around 12.0‐dpc. It requires the presence of regulatory DNA encompassed within a maximum of 370‐bp upstream of the translation start site of the gene, delimited by the presence of an upstream housekeeping gene (SAP‐62). Following this initial transient phase, a second phase seems to account for the persistence of AMH gene expression until the onset of puberty. As the 370‐bp regulatory region is not sufficient on its own to allow the triggering of this second phase, it seems possible that additional control elements are required for normal AMH expression throughout testicular development. The complete array of regulatory elements remains to be located. Mol. Reprod. Dev. 59:256–264, 2001. © 2001 Wiley‐Liss, Inc.
Estrogen receptor‐ and aromatase‐deficient mice provide insight into the roles of estrogen within the ovary and uterus*
Authors: Rosenfeld Cheryl S. , Roberts R. Michael , Lubahn Dennis B.
Published: August 2002

Estrogen receptor (ER)‐ (α, β, and both α and β) and aromatase (Ar) knockout (KO) mice have been created to assess the biological effects of estrogens. This review article discusses the ovarian and uterine phenotypes of these mice. The data obtained have confirmed some older inferences about how the steroid acts, but have also revealed some unexpected aspects of estrogen action. Mol. Reprod. Dev. 59:336–346, 2001. © 2001 Wiley‐Liss, Inc.
Storage in the yolk platelets of low MW DNA produced by the regressing follicle cells
Authors: Motta C.M. , Tammaro S. , Cicale A. , Indolfi P. , Iodice C. , Spagnuolo M.S. , Filosa S.
Published: August 2002

The present work was carried out to clarify the nature and origin of the yolk DNA present in vitellogenic oocytes of the lizard Podarcis sicula. Morphological and biochemical evidences indicate that it has an intrafollicular origin, from the apoptotic bodies resulting from follicle cells regression at the end of previtellogenesis. This conclusion is reinforced by the observation that the oocyte membrane, in in vitro experiments, is unpermeable to exogenous DNA. Biochemical evidences reveal that the yolk DNA has a low (200bp) molecular weight and this suggests that it is produced by the endonucleases typically involved in apoptotic DNA laddering. Indeed, immunocytochemical analyses demonstrate that follicle cells contain significant amounts of DNAse I. In immunoblots, carried out during different periods of the ovarian cycle, the enzyme shows a MW of about 33, 66 or 100 kDa thus indicating that its activity in the follicle of Podarcis is modulated by dimerization and/or binding to regulatory factors. Mol. Reprod. Dev. 59: 422–430, 2001. © 2001 Wiley‐Liss, Inc.
Distribution of lectin‐binding glycosidic residues in the hamster follicular oocytes and their modifications in the zona pellucida after ovulation
Authors: El‐Mestrah Majid , W. K. Kan Frederick
Published: August 2002

In the present study, we have employed a battery of colloidal gold‐tagged lectins as probes in conjunction with quantitative analysis to demonstrate the distribution and changes of carbohydrate residues in the hamster zona pellucida (ZP) during ovarian follicular development and during transit of the oocyte through the oviduct after ovulation. High‐resolution lectin–gold cytochemistry performed on thin sections of LR White‐embedded ovaries revealed a moderate to strong reactivity to WGA, PNA, DSA, AAA, and MAA over the entire thickness of the ZP of ovarian oocytes at different stages of follicular development. Labeling intensity over the ZP progressively increased as follicles matured in the ovary. In parallel, there was an association of labeling by gold particles with cortical granules, stacks of Golgi saccules, and complex structures called vesicular aggregates in the oocyte proper especially during the late stages of follicular growth. In contrary, labeling with each of HPA, DBA, and BSAIB4 was absent in the ovary but was found to be localized over Golgi complexes and secretory granules in the non‐ciliated secretory cells of the oviduct. When ovulated oocytes were labeled with each of HPA, WGA, RCA‐I, PNA, DSA, BSAIB4, AAA, MAA, and DBA, the ZP and several organelles in the oocyte proper presented a differential distribution of lectin‐binding sites. Quantitative analysis was also performed on labeling by lectin–gold complexes that bind specifically to the ZP of mature follicular and ovulated oocytes. Quantitative evaluation revealed heterogeneous labeling between the inner and the outer zone of the ZP. A significant increase in the labeling densities in both inner and outer ZP was noted when tissue sections of ovulated oocytes were labeled with RCA‐I or AAA. Tissue sections of ovaries labeled with WGA demonstrated a significant increase in the density of labeling in the outer layer of the ZP. Labeling by PNA, DSA, and MAA, however, showed a significant decrease in both the inner and outer portions of the ZP. Together, these results suggest that in the hamster, glycoproteins carrying specific sugar residues are added to the ZP of ovarian follicles during the early stages of folliculogenesis and are processed through a common secretory machinery, and that there is a significant change in both the sugar moieties and distribution of glycoproteins in the ZP following ovulation. Our results also showed that the hamster oviduct plays an important role in contributing certain glycoproteins to the ZP suggesting that the sugar moieties of these oviductal glycoproteins may have functional significance in fertilization. Mol. Reprod. Dev. 60: 517–534, 2001. © 2001 Wiley‐Liss, Inc.
Magnetic resonance microscopy of morphological alterations in mouse trabecular bone structure under conditions of simulated microgravity
Authors: Gardner John R. , Hess Christopher P. , Webb Andrew G. , Tsika Richard W. , Dawson M. Joan , Gulani Vikas
Published: August 2002

This work describes the use of magnetic resonance (MR) microscopy to examine changes in tibial trabecular bone structure in mice following 28 days of hindlimb suspension, a model simulating the effects of microgravity in rodents. In this first MR study involving mice, analysis of 3D images showed that apparent bone volume fraction, trabecular number, and trabecular thickness were decreased, and apparent trabecular spacing increased, significantly (P < 0.05) in hindlimb‐suspended mice compared to controls. These changes agreed well with light microcopy measurements from an independent study and also with actual spaceflight experiments with rats. Magn Reson Med 45:1122–1125, 2001. © 2001 Wiley‐Liss, Inc.