bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular motions in crystalline and mesomorphic forms of poly(diethylsiloxane)
Authors: Litvinov V. M. , Macho V. , Spiess H. W.
Published: April 2003

Molecular motions in low molar mass (46200 g mol—1) poly(diethylsiloxane) (PDES) are studied by 2H NMR. From DSC measurements the existence of the crystalline phases α1, β1 and α2, β2, as well as a pronounced mesogenic phase αm, is clearly established. Based upon calculations of averaged field gradient tensors based on cone models a detailed motional analysis in the different phases has been conducted. At low temperatures the only motion present besides methyl rotation are librations of the ethyl groups with amplitudes below 25°. The motion in the conformational disordered phase is characterized by conformational changes within the side chains, accompanied by occasional rotations through angles larger than 70° within the backbone. The flexibility of the ethyl groups, however, is limited by steric hindrance, prohibiting a full rotation. This situation is observed also in the meso phase where there is an additional rotational degree of freedom around the main chain axis.
Dielectric anomalies in the β‐relaxation of glassy 1,4‐polybutadiene
Authors: Hansen C. , Richert R.
Published: April 2003

We have measured the dielectric relaxation of the polymeric glass‐former 1,4‐polybutadiene in the glassy and supercooled liquid state. The loss spectra ϵ″ of the β‐relaxation are measured between the lower detection limit at T = 125 K and T = 225 K > Tβ, with Tβ ≈ 210 K being the α‐β‐merging temperature. The related storage data ϵ′(ω) indicates that the β‐process is a signature of supressing the higher frequency polarization with increasing temperature, rather than giving rise to additional polarizability at frequencies below the average relaxation frequency of the β‐process. This observation, as confirmed by data obtained for o‐terphenyl and salol, contradicts the previous understandings of the mechanism underlying the Johari—Goldstein‐type β‐process in glasses. A tentative link between the β‐process and high frequency vibrational modes is established.
New synthesis, thermal properties and textures of cholesteric poly[oxy(1,2‐butene)oxycarbonyl‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylenecarbonyloxy‐1,4‐phenylenecarbonyl], PTOBEE
Authors: Pérez‐Méndez M. , Marco C.
Published: April 2003

Liquid crystal poly[oxy(1,2‐butene)oxycarbonyl‐1,4‐phenyleneoxycarbonyl‐1,4‐phenylenecarbonyloxy‐1,4‐phenylenecarbonyl], PTOBEE, has been synthesized in a different way than the previously reported nematic and it has been obtained as cholesteric, although synthesized from a racemic mixture of the 1,2‐butanediol involved. Stereoselective solubilization of one enantiomer during its decantation in toluene, at the reaction temperature, explains why this chiral polymer phase appears. Evidence of this could be precisely obtained when a white solid recrystallized within the same toluene after the filtration of the polymer, being identified as (—) PTOBEE with a value of [α] = −2.33 [0.0056 mol/1, toluene].
Order and molecular motion in wholly aromatic copolyesters
Authors: v. Stein F. , Martin A. , Gronski W. , Blackwell J. , Chvalun S. N. , Kricheldorf H. R.
Published: April 2003

The order and molecular dynamics of wholly aromatic thermotropic copolyesters prepared from hydroxybenzoic acid (HBA), hydroquinone (HQ) and phenoxyterephthalic acid (Ph‐O‐TPA) have been studied by X‐ray analysis and deuteron NMR spectroscopy of specimens containing either deuterated hydroquinone or deuterated phenoxy side‐chain units. X‐ray analysis shows the coexistence of nematic and three‐dimensionally ordered regions that are characterized by registry of adjacent chains with interleaved side groups. The molecular motions in these nematic/three‐dimensionally ordered polymers are compared to those of a highly crystalline copolyester prepared from deuterated TPA and HQ. In the fast motional limit the motion in the crystalline system is characterized by 180° flips about the TPA axis, whereas in the nematic/three‐dimensionally ordered copolyester the same type of axially symmetric spectrum is observed for both the nematic and the three‐dimensionally ordered regions. The motion of the HQ units is characterized by rotational diffusion about the C1C4 axis, augmented by fast rotational fluctuation of this axis about the main‐chain direction. A model of free rotation about the axis of the phenyl group augmented by librations of restricted amplitude about the PhO‐TPA bond for the ordered regions superimposed by slow axial motions about the main‐chain axis in the nematic phase is consistent with both the NMR data and X‐ray analysis.
Real‐space composition–depth profiling in polymeric samples to 3 nm resolution using the 2H(3He, 1H)4He nuclear reaction
Authors: Kerle T. , Scheffold F. , Losch A. , Steiner U. , Schatz G. , Klein J.
Published: April 2003

Direct depth profiling techniques to date have largely lacked the necessary depth resolution to investigate interfacial phenomena of the order of the bulk correlation length (5—10 nm for a wide range of systems). Here we investigate the optimal spatial resolution and depth of probe that may be attained for composition — depth profiling of polymeric samples via nuclear reaction analysis (NRA) using the 2H(3He, 1H)4He reaction. We find that the spatial resolution can be greatly improved by using a grazing incidence geometry of the incident 3He beam on the sample, and analyzing the emitted protons in a backwards direction. This results in spatial resolutions down to about 3 nm at the sample surface, compared to a value of some 7 nm or more previously reported in earlier studies when emitted α‐particles were detected in the forward direction. At the same time the depth to which samples can be profiled via the backwards emitted protons may be considerably extended relative to the α‐particle detection mode, when the 3He beam impinges on the sample surface at normal incidence (up to about 4 μm into the sample for incident energies of 1.2 MeV in the proton‐detection mode compared to only 1 μm for the equivalent α‐particle detection mode).
Rubber toughening of polystyrene–acrylonitrile copolymers
Authors: Ramsteiner F. , McKee G. E. , Heckmann W. , Fischer W. , Fischer M.
Published: April 2003

The efficiency of rubber toughening of PSAN depends on the size of the rubber particles, their agglomeration, the deformation rate, the temperature, and the orientation of the polymer molecules. Large particles are more effective than small particles. By a suitable choice of processing, however, small particles can agglomerate, forming large soft units and improving in this way impact toughness. At high deformation rates crazing or/and stretching of the matrix wall between the rubber particles must be activated for ductility, otherwise the material is brittle. The temperature at impact must be above the glass transition temperature of the rubbery phase for toughening. Increasing the orientation of the material decreases the tendency for craze formation with the consequence of embrittlement, if stretching is not activated.
A new approach to polymer crystallization used in an analysis of data of syndiotactic polypropylene
Authors: Strobl G.
Published: April 2003

Under the conditions of “normal growth” on rough surfaces, crystallization rates follow from the balance between the attachment and detachment of the chain sequences building up the layer‐like crystallites. In the proposed model, detachment rates are related to the change in the mean‐field potentials experienced in the crystal and the melt; attachment rates are associated with the population number of straight sequences in the melt. Both rates show an exponential dependence on the sequence length. Combination of this picture with the basic kinetic criterion that the crystallite thickness found at a chosen crystallization temperature maximizes the growth rate yields equations that agree with the general observations. A detailed check of the model predictions is carried out in a discussion of data recently obtained for syndiotactic polypropylene. Attachment rates calculated using an RIS treatment are in fair agreement with those derived from the experimental data on the basis of the model.
N‐benzhydryl‐glycolamide: The first protecting group in peptide synthesis with a strong conformational bias
Authors: Crisma Marco , Formaggio Fernando , Ruzza Paolo , Calderan Andrea , Elardo Stefano , Borin Gianfranco , Toniolo Claudio
Published: April 2003

We have synthesized and examined the preferred conformation of a set of N‐benzhydryl‐glycolamide esters from Nα‐protected (or Nα‐blocked) α‐amino acids. Experiments were performed in CDCl3 solution by Fourier transform infrared absorption and 1H‐NMR techniques, and in the crystalline state by x‐ray diffraction. The results of our analysis strongly support the view that this type of Nα‐acylated α‐aminoacyl esters has a marked tendency to fold into a β‐turn conformation, the nature of which is dictated by the structural propensity of the amino acid constituent at the i+1 position. © 2003 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 71:17–27, 2003
Structure–activity relationships of de novo designed cyclic antimicrobial peptides based on gramicidin S
Authors: Lee Darin L. , Hodges Robert S.
Published: April 2003

The cyclic β‐sheet structure possessed by the 10‐residue antibiotic peptide gramicidin S was taken as the structural framework for the de novo design of biologically active peptides with membrane‐active properties. We have shown from previous studies that gramicidin S is a broad‐spectrum antibiotic effective against Gram‐positive bacteria, Gram‐negative bacteria, and fungi, but is toxic to human red blood cells. We tested the effect of ring size on antimicrobial activity and hemolytic activity on peptides varying from 4 to 16 residues. Interestingly, we were able to dissociate hemolytic activity and antimicrobial activity by increasing the ring size of the peptide to 14 residues (peptide GS14). Furthermore, we increased specificity for microbial membranes while decreasing toxicity to red blood cells by substituting enantiomers (D‐amino acids for L‐amino acids and vice versa) into the GS14 sequence. The enantiomeric substitutions all disrupted β‐sheet structure in benign medium and decreased peptide amphipathicity. The least amphipathic peptide, produced by substituting a D‐Lys at position 4 of GS14 (peptide GS14K4), also had the highest therapeutic index, i.e., highest degree of specificity for microbial cells over human cells. Solution structures of GS14 analogs solved by NMR spectroscopy showed that the D‐amino acid side chain was located on the nonpolar face of GS14K4. Another analog, a β‐sheet peptide with reduced amphipathicity (peptide GS14 K3L4), also had a lysine (lysine 3) on the nonpolar face as determined by the NMR structure. Both GS14K4 and GS14 K3L4 had reduced amphipathicity relative to GS14 and much higher therapeutic indices. Finally, the alteration of the nonpolar face hydrophobicity of GS14K4 analogs provided a range of activities and specificities, where the peptides with the intermediate hydrophobicities among the series had the highest therapeutic indices. The optimal peptide hydrophobicities varied depending on the microorganism being tested, with higher hydrophobicity requirements against Gram‐positive bacteria and yeast compared with Gram‐negative microorganisms. The net result of these studies suggests that it is possible to rationally design a cyclic membrane‐active antimicrobial peptide with high specificity towards prokaryotic (bacterial and fungal) membranes and minimal toxicity to eukaryotic (e.g., mammalian) membranes. © 2003 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 71: 28–48, 2003
Structure–activity relationships of dynorphin analogs substituted in positions 2 and 3
Authors: Schlechtingen Georg , DeHaven Robert N. , Daubert Jeffrey D. , Cassel Joel , Goodman Murray
Published: April 2003

Following up on the observation that the dynorphin analog [Pro3]Dyn A(1–11)–NH2 2 possesses high affinity and selectivity for the κ opioid receptor, a number of related peptides were prepared and characterized by radioligand binding and [35S]GTPγS assays. While incorporation of 2‐azetidine carboxylic acid in position 3 led to the equally potent analog 3, the corresponding analog containing piperidine‐2‐carboxylic acid showed a nearly 90‐fold reduction in κ affinity. Differential preferred bond angles ϕ in the three building blocks might account for these observations. Compounds 2 and 3 were κ antagonists with IC50 values of 380 and 350 nM, respectively. The Sar3 analog 7 and the Sar2 analog 8 were κ agonists, with greater selectivity than Dyn A(1–11)–NH2 1. In view of their high κ affinities (8: Ki = 1.5 nM; 2: Ki = 2.4 nM), the new analogs were surprisingly weak κ agonists or antagonists, e.g., the EC50 value for the agonist 8 was 280 nM. Different κ receptor subtypes in binding vs functional assays can not account for these results, since both assays were performed using the same membrane preparation. © 2003 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 71: 71–76, 2003
Trends in leukemia incidence and survival in the United States (1973–1998)
Authors: Xie Yang , Davies Stella M. , Xiang Ying , Robison Leslie L. , Ross Julie A.
Published: April 2003

BACKGROUND

It is estimated that each year, approximately 30,800 individuals will be diagnosed with leukemia in the United States and 21,700 individuals will die of the disease. Although the overall incidence of leukemia has been declining in the United States, recent reports suggest that incidence rates may be increasing for certain age and racial groups.

METHODS

Leukemia incidence (including acute lymphoblastic leukemia [ALL], acute myeloid leukemia [AML], chronic myeloid leukemia [CML], and chronic lymphoblastic leukemia [CLL]) and 5‐year survival rates were obtained from the Surveillance, Epidemiology, and End Results (SEER) program. Specific rates for age (birth–19, 20–44, 45–64, and 65 + years), gender, and race (black, white) were also examined.

RESULTS

A total of 66,404 cases of leukemia were identified for the period 1973–1998 in the nine reporting SEER sites. For children younger than 20 years old, the overall incidence rate of leukemia increased significantly (estimated annual percent change [EAPC] = 0.5%, 95% confidence interval [CI] = 0.1–0.9), whereas the rate decreased significantly among the group 65 years and older (EAPC = − 0.3, 95% CI = − 0.5 to − 0.1). Incidence rates for CLL and CML decreased significantly during this time period, whereas incidence rates for AML remained stable. Children younger than 20 years old experienced a 15% increase in the 5‐year survival rates for both ALL and AML when comparing the two 10‐year periods of 1974–1983 and 1984–1993. In contrast, there was little overall improvement in survival for adults 45 years and older. In particular, there was a notable decrease in the overall 5‐year survival for blacks older than 65 years and for black males older than 44 years.

CONCLUSIONS

Although the current study confirmed some of the results noted in other populations, the observed overall decline in leukemia survival for blacks is surprising and warrants further investigation. Cancer 2003;97:2229–35. © 2003 American Cancer Society.

DOI 10.1002/cncr.11316
Genetic heterogeneity in lung and colorectal carcinoma as revealed by microsatellite analysis in plasma or tumor tissue DNA
Authors: Beau‐Faller Michèle , Weber Jean‐Christophe , Schneider Anne , Guèrin Eric , Gasser Bernard , Ducrocq Xavier , Jaeck Daniel , Wihlm Jean‐Marie , Quoix Elisabeth , Gaub Marie‐Pierre
Published: April 2003

BACKGROUND

Determination of tumor clonality has implications for molecular characterization and the optimal treatment of cancer. Allelotyping allows detection of the two alleles, maternal and paternal, and provides additional information regarding clonal genetic defects. The presence of allelic imbalances (AI) in tumors is a general event, but is not necessary at the same allele (alternative AI). The authors' goal was to determine whether the presence of alternative AI (AA) was a marker of heterogeneity and prognosis.

METHODS

To further analyze the heterogeneity of lung tumors, tumor DNA released in the plasma was compared with primary tumor DNA from 24 lung carcinoma patients. The comparison was performed by allelotyping using 12 microsatellites targeting 9 chromosomal regions, taking in each case leukocyte DNA as reference. To extend and confirm these observations, 26 primary colorectal carcinomas with paired synchronous liver metastasis were analyzed using an enlarged panel of 33 microsatellites.

RESULTS

AA were observed in 40% (20 of 50) of all patients, in 25% (6 of 24) of lung carcinoma patients but at a higher level, and in 54% (14 of 26) of colorectal carcinoma patients. They affected different chromosome localizations and each tumor stage. In both types of cancer, patients with AA had a higher AI mean frequency in their primary tumor.

CONCLUSIONS

Detection of AA is an original marker of heterogeneous tumors, demonstrating that independent events occurred on specific genetic sites required for cancer progression. Cancer 2003;97:2308–17. © 2003 American Cancer Society.

DOI 10.1002/cncr.11324
Preoperative and postoperative dextromethorphan provides sustained reduction in postoperative pain and patient‐controlled epidural analgesia requirement
Authors: Weinbroum Avi A. , Bender Benjamin , Bickels Jacob , Nirkin Alexander , Marouani Nissim , Chazam Shoshana , Meller Isaac , Kollender Yehuda
Published: April 2003

BACKGROUND

Pain is mediated centrally by N‐methyl‐D‐aspartate (NMDA) receptors. The antinociceptive effects of preincision dextromethorphan (DM), an NMDA antagonist, have been demonstrated in surgical patients under general or epidural anesthesia. The authors investigated the effects of DM on postoperative pain and other parameters in patients undergoing surgery for bone malignancy under standardized combined general and epidural anesthesia using patient‐controlled epidural analgesia (PCEA) postoperatively.

METHODS

Patients received placebo or DM 90 mg (30 patients per group) in a double‐blind manner preoperatively and on each of the two following days. Postoperative PCEA consisted of 1.6 mg ropivacaine plus 4 μg/mL fentanyl both continuously and by demand up to 96 hours, starting when subjective pain intensity was greater than or equal to 4/10 (visual analog score). Rescue drugs on demand (paracetamol or dipyrone orally) were also available.

RESULTS

The DM patients experienced about 50% (P < 0.01) less pain than their placebo counterparts for more than 2 postoperative days and they rated their overall maximal pain intensity by one‐half that estimated by the placebo‐treated patients (P < 0.01). The DM group also consumed 30–50% less epidural analgesics than the total amount consumed by the placebo‐medicated group (P < 0.01) and demanded significantly (P < 0.05) fewer rescue drugs on the first postoperative day. They were less sedated (40–60%, P < 0.01) and reported 50% fewer overall side effects (P < 0.05). The groups were similar for the need for urinary catheterization, time of first ambulation, and/or discharge home.

CONCLUSIONS

A 3‐day DM administration is associated with better pain reduction in patients undergoing surgery for bone malignancy under combined general and epidural anesthesia with postoperative PCEA compared with placebo without increasing side effects. Cancer 2003;97:2334–9. © 2003 American Cancer Society.

DOI 10.1002/cncr.11330
Older age predicts a decline in adjuvant chemotherapy recommendations for patients with breast carcinoma
Authors: DeMichele Angela , Putt Mary , Zhang Yawei , Glick John H. , Norman Sandra
Published: April 2003

BACKGROUND

The appropriate use of adjuvant chemotherapy for elderly women with breast carcinoma remains controversial. Efficacy data in women age ≥ 70 years are scarce, resulting in a lack of clear guidelines for patients in this age group. Although several studies have demonstrated decreasing use of chemotherapy with age, none specifically examined its use in an elderly cohort of patients who were deemed eligible for such therapy based on consensus guidelines, simultaneously examining the impact of comorbidity and previous history of malignant disease on these recommendations.

METHODS

The authors examined adjuvant chemotherapy use among chemotherapy‐eligible patients age ≥ 50 years who were evaluated in a tertiary care cancer center. Associations between patient age and 1) physician recommendation for adjuvant chemotherapy, 2) recommended treatment regimen, and 3) patient acceptance of the treatment plan recommended were examined, adjusting for the impact of aggressive tumor characteristics, medical comorbidity, previous history of malignant disease, and features of the treatment setting.

RESULTS

Of the 208 chemotherapy‐eligible patients who were studied, 74% overall were recommended chemotherapy. Chemotherapy was recommended to 92% of women age 50–59 years compared with 77% of women age 60–69 years and 23% of women age ≥ 70 years. Increasing age was associated strongly with a decreasing likelihood of receiving a recommendation in favor of chemotherapy. After adjusting for estrogen receptor status, previous history of malignant disease, comorbidity score, and prognostic group, the odds of receiving a recommendation in favor of chemotherapy fell by 22% per year or 91% per 10‐year interval, and the rate of decline did not change significantly at age ≥ 70 years. We found no age‐related differences in either the drug regimens recommended or patient acceptance rates for adjuvant therapy.

CONCLUSIONS

Age was associated strongly and independently with physician recommendation for adjuvant chemotherapy among a group of older women who were eligible specifically for such therapy. Medical comorbidity and a history of previous malignant disease did not alter this correlation significantly, although the latter was a significant predictor of chemotherapy use. Further studies clearly are needed to determine the underlying reasons for this strong age effect and to explore strategies that will optimize the utilization of this potentially curative therapy in the elderly. Cancer 2003;97:2150–9. © 2003 American Cancer Society.

DOI 10.1002/cncr.11338
BRCA‐related ovarian carcinoma
Authors: Rubin Stephen C.
Published: April 2003

The author comments on a report in this issue of Cancer by investigators who used clinical response endpoints and chemoresistance testing to confirm the improved survival of women with hereditary ovarian carcinoma compared with women who had sporadic ovarian carcinoma. The possible use of BRCA mutation status to improve patient care, the future of translational research, and the difficulties in proceeding with large‐scale prospective trials are among the topics discussed.

See also pages 2187–95.
Sentinel lymph node biopsy: Beyond melanoma and breast carcinoma
Authors: McMasters Kelly M.
Published: April 2003

In this issue of Cancer, two groups of investigators present their initial experience with sentinel lymph node (SLN) biopsy in the staging of sweat gland carcinomas. The reports suggest that it is possible to identify clinically occult lymph node metastases from sweat gland carcinoma using SLN biopsy similar to the way that surgeons around the world now routinely stage the regional lymph nodes in patients with melanoma and breast carcinoma. These two articles raise the question of when does it make sense to apply SLN biopsy to cases beyond melanoma and breast carcinoma?

See also pages 2279–84 and 2285–9.
Physician attitudes toward cytotoxic chemotherapy use in patients with advanced prostate carcinoma
Authors: Oh William K. , Tully Patrice , Kantoff Philip W. , Regan Meredith M.
Published: April 2003

BACKGROUND

Attitudes toward the use of chemotherapy in patients with prostate carcinoma have changed as new therapeutics have demonstrated efficacy. This is important as randomized trials using chemotherapy are proposed. The authors used a questionnaire to investigate the attitudes of physicians in the New England area who care for patients with advanced prostate carcinoma.

METHODS

A 15‐question survey was developed and mailed in the year 2000. No monetary incentives were used to encourage return of surveys. Baseline demographic data were obtained, including type of practice and number of patients with prostate carcinoma seen. Urologists, radiation oncologists, and medical oncologists were asked whether they had recommended chemotherapy for patients with prostate carcinoma, what they perceived as the effectiveness of specific drugs, what concerns they had regarding chemotherapy, and the appropriateness of chemotherapy in three hypothetical patient scenarios.

RESULTS

Of 1068 surveys that were delivered to practicing physicians, 232 surveys (22%) were returned and evaluable. Forty‐six percent of respondents were urologists, 41% were medical oncologists, and 10% were radiation oncologists. Eighty‐seven percent of respondents had recommended cytotoxic chemotherapy to their patients. Four agents were rated as moderately effective to very effective by 41–60% of respondents who rated effectiveness: estramustine, mitoxantrone, paclitaxel, and docetaxel. In three hypothetical patient scenarios of hormone‐refractory prostate carcinoma, only one patient was judged as an appropriate candidate for chemotherapy. In a multivariate analysis, female physicians and physicians with practices comprised of > 25% patients with hormone‐refractory prostate carcinoma were more likely to recommend chemotherapy. Concerns regarding severe toxicity and lack of benefit were among the most influential on respondent decisions to use chemotherapy.

CONCLUSIONS

Most physicians who cared for patients with prostate carcinoma had recommended chemotherapy for patients with hormone‐refractory disease. There were differences between specialties regarding the likelihood of recommending chemotherapy and clinical judgment regarding which patients were appropriate candidates for chemotherapy. Cancer 2003;97:2171–9. © 2003 American Cancer Society.

DOI 10.1002/cncr.11344
Building leasing at the department of energy's Hanford site: Lessons learned from commercial reuse
Authors: Abbotts John , Ertell Katherine B. , Leschine Thomas M. , Takaro Tim K.
Published: April 2003

The mission at many locations of the U.S. Department of Energy's (DOE) complex has shifted
from materials production for atomic weapons to environmental remediation. DOE and neighboring communities are
interested in diversifying local economies, including through the transfer of DOE property for commercial reuse.
But Department leasing programs have raised occupational health concerns in two locations. A 1997 DOE review of
leasing at the Oak Ridge, Tennessee, site, and leasing at the Hanford site in central Washington state led us to
examine the building leasing program at Hanford. Because of past operations in Building 313, we recommended that
the building be surveyed for beryllium. Results were positive, and the tenant company may have generated the
beryllium detected. We compare lessons learned from Oak Ridge and Hanford. © 2003 Wiley Periodicals,
Inc.
A meta‐analysis of the non‐monetary effects of employee health management programs
Authors: DeGroot Timothy , Kiker D. Scott
Published: April 2003

This study was undertaken to review the literature on employee health management programs (EHMPs). We
explored the history and characteristics of systematic organizational efforts to improve workforce health and
well‐being. We believe that a historical perspective provides some insight into the economic, political,
and social factors that have influenced the trend toward organizationally sanctioned health‐promotion
efforts. Further, we investigated the likely effects of these programs on valued‐behavioral organizational
outcomes such as employee performance, employee satisfaction, absenteeism, and voluntary turnover. Our findings
show that voluntary general‐focus programs are unrelated to job performance, and voluntary programs are
negatively related to absenteeism, but effects on absenteeism wane when the program is not voluntary. Moreover,
EHMPs are minimally related to job satisfaction and slightly related to turnover. These results, examining
behavioral outcomes of EHMPs, question the ability of EHMPs to provide desired behavioral changes in employees,
changes that organizations seek to maximize such as increased performance. Are EHMPs more than just socially
acceptable programs that help individuals with health problems? © 2003 Wiley Periodicals, Inc.
Designing and implementing global staffing systems: Part II—Best practices
Authors: Ryan Ann Marie , Wiechmann Darin , Hemingway Monica
Published: April 2003

As a companion piece to Wiechmann et al. (2003), practical guidance regarding how to implement a global
staffing system is provided. Best practices were derived from interviews with key informants in six organizations
recognized as leading in the area of global staffing. Best practices related to system acceptability, development,
and implementation are presented. © 2003 Wiley Periodicals, Inc.
Radiation‐induced leukocyte adhesion to endothelium in normal pancreas and in pancreatic carcinoma of the rat
Authors: Ryschich Edward , Harms Wolfgang , Loeffler Thorsten , Eble Michael , Klar Ernst , Schmidt Jan
Published: April 2003

High‐dose radiation is known to induce an inflammatory reaction in normal and malignant tissue including leukocyte infiltration. The influence of radiation on leukocyte‐endothelium interaction in tumor tissue, which precedes leukocyte migration, has not yet been investigated to our knowledge. In our study, intravital microscopy was used to compare the radiogenic effects on leukocyte‐endothelium interaction and leukocyte migration in healthy and malignant pancreatic tissue in vivo. An established model of ductlike pancreatic cancer (DSL6A) of syngeneic Lewis rats was utilized. Irradiation with 15 Gy increased the high‐affinity leukocyte‐endothelium interaction both in normal and malignant tissue. The low‐affinity leukocyte‐endothelium interaction was not significantly altered. Radiation‐induced tumor cell death 12 days after radiation was significantly higher in tumors with moderate and severe leukocyte infiltration compared to low leukocyte infiltration. Thus, radiation‐induced leukocyte infiltration in pancreatic carcinoma correlates with the extent of tumor cell death. © 2003 Wiley‐Liss, Inc.
Polymorphic markers in the 5α‐reductase type II gene and the incidence of prostate cancer
Authors: Lamharzi Najib , Johnson Melissa M. , Goodman Gary , Etzioni Ruth , Weiss Noel S. , Dightman Douglas A. , Barnett Matt , DiTommaso Dante , Chen Chu
Published: April 2003

In the prostate, the enzyme encoded by the SRD5A2 gene (5α‐reductase) converts testosterone to dihydrotestosterone, a potent androgen that has been hypothesized to play a role in the genesis of prostate cancer. Several polymorphisms have been identified in the SRD5A2 gene, including a valine‐to‐leucine substitution (V89L) at codon 89, a variable number of TA dinucleotide repeats and a missense substitution at codon 49 resulting in an amino acid substitution of alanine with threonine (A49T). To investigate the influence of these polymorphisms on prostate cancer risk, we conducted a case‐control study nested within the Beta‐Carotene and Retinol Efficacy Trial. Genotypes were determined by PCR‐based capillary electrophoresis using genomic DNA isolated from 300 cases and 300 controls matched on the basis of race, age at enrollment (within 5 years), enrollment study center and year of randomization. There was no association between V89L genotypes and prostate cancer risk. The age‐ and race‐adjusted odds ratio (OR) associated with the VL and LL genotypes were 1.06 (95% confidence interval (CI) = 0.75‐1.49) and 0.99 (95% CI = 0.57‐1.73), respectively, as compared to the VV genotype. The age‐ and race‐adjusted odds ratio for men having 1 TA(9) or TA(18) allele was 0.98 (95% CI = 0.64‐1.48) when compared to men without TA repeats. The corresponding odds ratio for men without the TA(0) alleles was 0.68 (95% CI = 0.21‐2.19). The age‐ and race‐adjusted odds ratio associated with having at least 1 T allele at codon 49 was 1.11 (95% CI = 0.58‐2.11), as compared to the AA genotype. Our results do not support the hypothesis that the V89L and A49T polymorphisms in the SRD5A2 gene are related to the risk of prostate cancer, but are compatible with the suggestion from earlier studies that men who are homozygous for the TA(9) or (18) alleles and men who have the TA(9)/TA(18) genotype are at a modestly reduced risk. © 2003 Wiley‐Liss, Inc.
Overexpression of leukocyte‐type 12‐lipoxygenase promotes W256 tumor cell survival by enhancing αvβ5 expression
Authors: Pidgeon Graham P. , Tang Keqin , Rice Renee L. , Zacharek Alex , Li Li , Taylor John D. , Honn Kenneth V.
Published: April 2003

The metabolism of arachidonic acid (AA) leads to the generation of biologically active metabolites that have been implicated in cell growth and proliferation, as well as survival and apoptosis. We have previously demonstrated that rat Walker 256 (W256) carcinosarcoma cells express the platelet‐type 12‐lipoxygenase (12‐LOX) and synthesize 12(S)‐ and 15(S)‐HETE as their major LOX metabolites. Here we show that Walker 256 cells also express leukocyte‐type 12‐LOX and that its overexpression in these cells significantly extends their survival and delays apoptosis when cells are cultured under serum‐free conditions. Under serum‐free conditions, the expression of leukocyte‐type 12‐LOX is upregulated. 12‐LOX‐transfected W256 cells had a more spread morphology in culture compared with wild‐type or mock‐transfected cells. Examination of W256 cells showed that the cells expressed a number of integrins on their surface. Overexpression of 12‐LOX enhanced the surface expression and focal adhesion localization of integrin αvβ5, while not affecting other integrins. Also, the 12‐LOX‐transfected W256 cells exhibited higher levels of microfilament content. Treatment of cells with monoclonal antibody to αvβ5 or cytochalasin B (a microfilament‐disrupting agent), but not antibodies to other integrin receptors, resulted in significant apoptosis, characterized by rapid rounding up and detachment from the substratum. These results show that the 12‐LOX pathway is a regulator of cell survival and apoptosis, by affecting the expression and localization of the αvβ5 integrin and actin microfilaments in Walker 256 cells. © 2003 Wiley‐Liss, Inc.
2‐connected 7‐coverings of 3‐connected graphs on surfaces
Authors: Kawarabayashi Ken‐ichi , Nakamoto Atsuhiro , Ota Katsuhiro
Published: April 2003

An m‐covering of a graph G is a spanning subgraph of G with maximum degree at most m. In this paper, we shall show that every 3‐connected graph on a surface with Euler genus k ≥ 2 with sufficiently large representativity has a 2‐connected 7‐covering with at most 6k − 12 vertices of degree 7. We also construct, for every surface F2 with Euler genus k ≥ 2, a 3‐connected graph G on F2 with arbitrarily large representativity each of whose 2‐connected 7‐coverings contains at least 6k − 12 vertices of degree 7. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 26–36, 2003
The infrared spectra and structures of polyisoprenes
Authors: Binder John L.
Published: April 2003

Evidence is offered which confirms, and in some cases, changes previously suggested assignments of bands in the spectra of Hevea and balata. In particular it is shown that bands at 764 (13.1 μ) and 742 cm.−1 (13.5 μ) are probably connected with vibrations of the cis‐ or trans‐C (CH3)CH group, a band at 11.30 cm.−1 (8.85 μ) is due to a CCH3 vibration of the cis‐C(CH3)CH group, a band at 1155 cm.−1 (8.68 μ) is due to the CCH3 vibration of the trans‐C(CH3)CH group. Likewise the bands at 1315 (7.60 μ) and 1325 cm.−1 (7.55 μ) are probably due to a CH vibration of the cis‐ and trans‐C(CH3)CH groups, respectively. The 1130‐cm.−1 band and the 1155‐cm.−1 band are found in spectra of polydimethylbutadiene and thus are probably group frequencies. The 1315 and 1325‐cm.−1 bands (shifted) are also found in polybutadiene and polypiperylene spectra and thus are probably group frequencies also. It is also shown that the 890‐, 1645‐, and 3077‐cm.−1 bands are best explained by the presence of an isopropenyl, CH2C(CH3) group. These assignments are based on a study of the polarization spectra, the spectra of maleic anhydride adducts and hydrogenated polyisoprenes, and on microstructure determinations.
The infrared spectra and structures of polybutadienes
Authors: Binder John L.
Published: April 2003

Assignments are suggested for many bands in the spectra of various kinds of polybutadienes which either confirm those deduced from olefin spectra or are new. In particular the band at 1355 cm.−1 (7.38 μ) is probably due to trans‐CHCH, that at 1311 cm.−1 (7.63 μ) is due to cis‐CHCH as is a band at 740 cm.−1 (13.5 μ). These assignments are based on the study of polarization spectra, of the spectra of hydrogenated polybutadienes and maleic anhydride adducts of polybutadienes and on isomerization experiments of cis‐1,4‐polybutadienes. Evidence is offered which indicates that presently known high cis‐1,4‐polybutadienes are not simply butadiene polymerized by cis‐1,4 addition and that probably other structures are present in the polymer. It is shown that the 1355‐ and 1311‐cm.−1 bands appear in the spectra of polypiperylenes and polyisoprenes (shifted somewhat in the latter spectra) and consequently are due to a CH vibration of the trans‐ or cis‐CHCH group. Thus they are group frequencies.
Cocatalysts for the linear polymerization of epoxides by dibutylzinc
Authors: Garty K. T. , Gibb T. B. , Clendinning R. A.
Published: April 2003

A study of the nature and quantity of materials that will react with dibutylzinc to act as cocatalysts for the polymerization of phenyl glycidyl ether has led to the finding of several very effective catalyst systems. These cocatalysts may be grouped in the following classifications: (1) highly effective: water and acetone; (2) effective: methanol, ethanol, n‐butanol, and oxygen; (3) slightly effective: isopropancl, tert‐butanol, diethylamine, n‐butyraldehyde, and phenol; and (4) inhibitors: acetic acid, ethyl acetate, and carbon dioxide. The poly(phenyl glycidyl ether) produced by these catalysts is a high melting (204°C.), high molecular weight crystalline polymer which is insoluble in most common organic solvents. Ethylene oxide and propylene oxide have also been polymerized by the dibutylzinc–water system to high molecular weight polymers in high yield. Epichlorohydrin, on the other hand, gave only low molecular weight oils in low yields, probably due to reaction of the catalyst species with the reactive chlorine of the monomer.
Melting transitions in diene polymers
Authors: Cooper W. , Smith R. K.
Published: April 2003

The melting transitions of natural rubber, cis‐polyisoprene, gutta‐percha, balata and synthetic trans‐polyisoprene, and cis‐polybutadiene have been examined by means of differential thermal analysis. Natural rubber melts over a wide range of temperature giving several transitions, the magniture and temperature of which depend on the experimental conditions. At heating rates feasible for differential temperature measurements the values observed are markedly below the equilibrium melting points. Natural and synthetic trans‐polyisoprenes possess similar melting points and extents of crystallinity. The ratio of the peaks associated with the α and the β forms is not only dependent on the rate of cooling and temperature of crystallization, but also on the temperature to which the sample was heated before crystallization. This is thought to be due to the persistance of crystalline nuclei in the polymer melt. Under certain conditions a small melting transition occurs at a lower temperature. Synthetic cis‐polyisoprenes show melting characteristics similar to those of natural rubber, but the upper transition is lower than that of the natural product and correlates with the cis content of the polymer. cis‐Polybutadienes melt slowly over a wide range of temperature below the characteristic melting transition which is dependent on the cis content. The highest melting point observed for a polymer of 98% cis content was +1°C.
A thermodynamic method for the comparison of the order distribution in cellulose and in other polymers
Authors: Ticknor L. B.
Published: April 2003

Previous definitions of order (i.e., lateral order) in cellulose materials have been essentially in terms of the experimental method and order has been interpreted as the extent of hydrogen bonding. These definitions are inadequate. Order is defined herein as the difference in free energy of the element of polymer in its present state and in a completely amorphous state. The free energy of swelling is equated to the conceptual process of fusion of the element of polymer plus mixing the amorphous and crosslinked (by crystallites) polymer with swelling agent as would be given by the Flory‐Huggins theory of mixing and the Flory‐Rehner or Hermans theories for the swelling of networks. For those elements of polymer for which the free energy of swelling is zero the free energy of fusion (i.e., “order”) may be determined. This limiting order of the polymer elements that are swollen may be reduced by lowering the pressure of the swelling agent if it is in the gaseous state or if the swelling agent is a liquid by mixing it with a nonswelling liquid. Such a variation in the swelling agent gives a variation in the quantity of polymer swollen. The summative mass order (quantity accessible vs. limiting order) and order distribution (slope of summative curve vs. limiting order) plots are made as usual. This method should give realistic qualitative comparisons of the order distribution among various samples of the same polymer, and it should be applicable to other crystalline polymers as well as to cellulose.
Radiolysis of the isomeric poly(butyl methacrylates)
Authors: Ungar Israel S. , Kircher John F. , Gager William B. , Sliemers Francis A. , Leininger Robert I.
Published: April 2003

A study has been made of the effect of gamma irradiation on the production of free radicals in poly(butyl methacrylates). A mechanism of radiation attack on the polymers is proposed. Free‐radical measurements and the determination of the products of irradiation have been used in establishing this mechanism. The effects of configuration of the ester chain on radiation susceptibility are discussed.
Probability matrices, chain dimensions and statistical thermodynamics for semicrystalline macromolecules
Authors: Tobolsky Arthur V.
Published: April 2003

In a previous paper the end‐to‐end dimensions of semicrystalline macromolecules were computed by the Markoff chain method, by use of a normalized probability matrix with two probability parameters α and p. The values of these parameters that actually obtain may result from kinetic conditions (as in rapidly quenched specimens) or the values may in some cases be equilibrium values that can be determined by statistical mechanical considerations. In this paper we calculate the overall partition function Q of a semicrystalline macromolecule by a method similar to that employed by Zimm and Bragg for polypeptide chains. Q is computed in terms of segment partition functions fr, fh, and fk. By working out the consequences of this Ising‐type model, we are able to relate α and p to fr, fh, and fk. In an appendix we show that the phenomenon of ceiling and floor temperatures in equilibrium polymerization can be regarded from the same mathematical point of view as the helix–coil transition. Moreover, the mathematical results from this approach can be correlated with the results previously obtained by Tobolsky and Eisenberg by direct application of the law of mass action.
Solution properties of polysaccharides. IV. Molecular weight and aggregate formation in methylcellulose solutions
Authors: Neely W. Brock
Published: April 2003

Light scattering has been employed to investigate the aqueous solution properties of partially methylated cellulose. The data indicate a random coil for the polymer with a stiffness characterized by a value of 21.8 A. for the effective bond length b. An increase in ionic strength in the methylcellulose solution causes aggregation which is temperature‐dependent. Once the aggregates are formed in the salt solution, they may be dispersed by lowering the temperature of the solution. Within probable error the intrinsic viscosity–molecular weight relation is given by [η] = 3.16 × 10−3 M̄w0.55 throughout the region investigated.
Effect of crystallization on the thermal stability of polyvinylphthalic acid and its methyl ester
Authors: Winslow Eugene C. , Marriott Jean A.
Published: April 2003

The synthesis of dimethyl 4‐vinylphthalate was accomplished by direct esterification of 4‐vinylphthalic acid with diazomethane. This monomer was polymerized stereospecifically by the use of boron trifluoride etherate. The polymer was crystallized by refluxing in n‐octane. The preparation of crystalline poly(4‐vinylphthalic acid) was realized by hydrolyzing crystalline poly(dimethyl 4‐vinylphthalate) with concentrated sulfuric acid. The thermal behaviour of the prepared polymers was studied by the techniques of differential thermal analysis and thermogravimetry. Crystallization apparently retards thermal breakdown somewhat but the temperature of major weight loss by volatilization is essentially the same for the crystalline and the noncrystalline polymer. Differential thermal analysis indicates that anhydride formation occurs in the noncrystalline polymeric acid at 200°C. This transition is less pronounced in the case of the crystalline polymer.
Fundamental studies on cationic polymerization. II. Mechanism and theory of inversion temperature
Authors: Kennedy J. P. , Kirshenbaum I. , Thomas R. M. , Murray D. C.
Published: April 2003

Further studies with the isobutene‐aluminum chloride‐methyl chloride system has led to a better understanding of the dependence of degree of polymerization on monomer concentration and on temperature. Polymerizations were also carried out in C14‐labeled methyl chloride to determine solvent incorporation in the polymer. A quantitative kinetic theory has been developed which explains the behaviour of the isobutene–aluminum chloride system in polar solvents such as methyl chloride, vinyl chloride, and ethyl chloride. The rate‐determining step in propagation is polymer activation, presumably by ion separation. The DP of the polymer is determined principally by two competing chain‐breaking processes; namely, chain transfer to monomer and/or chain breaking involving the solvent. The latter reaction becomes important in polar solvents at higher temperatures. The influence of phase separation has also been studied. The results indicate that the polymer molecule precipitates after it has under gone either a chain breaking or a chain termination reaction.