bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone marrow stem cells do not repopulate the healthy upper respiratory tract
Authors: Davies Jane C. , Potter Mike , Bush Andrew , Rosenthal Mark , Geddes Duncan M. , Alton Eric W.F.W.
Published: October 2002

Recent studies reported differentiation of both bone marrow and tissue‐specific stem cells into cells of other organs. The demonstration that bone marrow stem cells differentiate into human hepatocytes in vivo has raised the possibility of new therapeutic approaches for liver disease. For diseases such as cystic fibrosis (CF), correction of the respiratory epithelium is being attempted by gene therapy. Differentiation of bone marrow stem cells into epithelium of the lung and airway was recently reported in an animal model, and would provide an alternative approach. We examined the nasal epithelium of female patients up to 15 years after gender‐mismatched bone marrow transplantation. Donor‐derived epithelial cells were sought with a combination of Y‐chromosome fluorescence in situ hybridization and anti‐cytokeratin antibody.

In nasal brushing samples from 6 transplant‐recipients, a median of 2.5% (range, 0.7–18.1%) of nuclei was male and identified as being of donor‐origin. However, a complete absence of staining with anti‐cytokeratin antibodies confirmed that these were not epithelial cells, but were likely to be either intraepithelial lymphocytes or mesenchymal cells.

Following whole bone marrow transplantation, bone marrow progenitor cells do not differentiate into respiratory epithelium of the healthy upper airway. The differences between this and other studies could relate to the cells transplanted, to differential rates of turnover, or to the requirement for specific triggers to stimulate migration and differentiation. In the absence of such conditions, whole bone marrow transplantation is unlikely to provide a route for correction of the CF airway. Pediatr Pulmonol. 2002; 34:251–256. © 2002 Wiley‐Liss, Inc.
Transmission of colistin‐resistant Pseudomonas aeruginosa between patients attending a pediatric cystic fibrosis center
Authors: Denton M. , Kerr K. , Mooney L. , Keer V. , Rajgopal A. , Brownlee K. , Arundel P. , Conway S.
Published: October 2002

We report on an outbreak of colistin‐resistant Pseudomonas aeruginosa (CRPA) that occurred in a United Kingdom pediatric cystic fibrosis (CF) unit and involved six children over a period of 5 years. All CRPA‐positive children had received aerosolized colistin therapy before first isolation of resistant organisms (mean duration, 3.1 years). Four of the 6 had also received courses of intravenous colistin in the year before the first isolation of CRPA. No impact of CRPA acquisition on respiratory function, clinical condition, or radiological parameters could be demonstrated. Four of the 6 children carried isolates of CRPA indistinguishable on genotyping. Two of these 4 children were sisters. The other 2 were on the same ward together at time of first isolation, and subsequently shared overlapping admissions with one of the sisters.

While there is no conclusive evidence for the route of transmission, the frequency of overlapping in‐patient admissions between 3 of these patients is suggestive of patient‐to‐patient transfer in the nosocomial setting.

CF clinicians should be aware that colistin resistance can occur in P. aeruginosa, and some of these strains are capable of spread within CF units. Pediatr Pulmonol. 2002; 34:257–261. © 2002 Wiley‐Liss, Inc.
Do in‐line respiratory filters protect patients? comparing bacterial removal efficiency of six filters
Authors: Canakis Anne‐Marie , Ho Bernard , Ho Sharon , Kovach Danuta , Matlow Anne , Coates Allan L.
Published: October 2002

With all pulmonary function diagnostic and respiratory therapy equipment, cross‐infection has always been a concern, especially in the cystic fibrosis population, in whom pulmonary function tests are done routinely. The aim of this study was to identify and compare the bacterial removal efficiency (BRE, ability of a filter to remove microorganisms) of six different filters used in hospital settings: Microgard (MG), Spirobac (SB), PALL (PL), and KOKO (KK), used in the pulmonary function laboratory; and Clear‐Guard (CG) and Respigard (RG), used in ventilator circuits. Filters were tested in both saturated and nonsaturated conditions. A Pseudomonas aeruginosa suspension of 1 × 104 to 1 × 108 CFU/mL was nebulized onto each filter. A blood agar plate was held immediately downstream from the filter. Colony‐forming units (CFU) were then counted after 24 hr of incubation. A peak flow was applied across the spirometry filters. Bacterial thresholds of the filters were also identified (concentration of bacteria at which a filter no longer has 100% BRE).

There was a significant difference in BRE among the six filters in saturated states when challenged with 1 × 104 CFU/mL (MG, KK, CG, and RG, 100%; SB, 98.8%; PL, 42.7%; P = 0.003). There was no significant difference between saturated and nonsaturated states, or after application of a peak flow. Filter thresholds were significantly different (KK 1 × 108, MG 1 × 107, CG 1 × 106, RG 1 × 105, and SB and PL <1 × 104 CFU/mL).

In conclusion, when all filters are exposed to the same extreme challenges, significant differences exist in their ability to remove bacteria. Pediatr Pulmonol. 2002; 34:336–341. © 2002 Wiley‐Liss, Inc.
Adrenal insufficiency and testicular failure secondary to megestrol acetate therapy in a patient with cystic fibrosis
Authors: McKone Edward F. , Tonelli Mark R. , Aitken Moira L.
Published: October 2002

We present a case report of adrenal insufficiency and testicular failure in an adult cystic fibrosis (CF) patient due to megestrol acetate therapy. This is followed by a review of the literature on the use of megestrol acetate in the treatment of weight loss in CF, AIDS, and cancer, with particular emphasis on the adverse effects that should be looked for in CF patients. Pediatr Pulmonol. 2002; 34:381–383. © 2002 Wiley‐Liss, Inc.
Neuroendocrine differentiation of human prostatic primary epithelial cells in vitro
Authors: Rumpold Holger , Heinrich Elmar , Untergasser Gerold , Hermann Martin , Pfister Gerald , Plas Eugen , Berger Peter
Published: October 2002

BACKGROUND

Dispersed prostatic neuroendocrine cells are involved in growth regulation of the prostate and are considered to play a role in the pathogenesis of prostate carcinoma and benign prostatic hyperplasia (BPH). They are meant either to be derived from the neural crest during embryogenesis or by direct differentiation of the cells from locally present precursor cells.

METHODS

An in vitro model was developed for human prostatic epithelial and neuroendocrine cell differentiation. Minced explants from radical prostatectomies were seeded on collagen I–coated plates.

RESULTS

The majority of outgrowing cells were basal cells, positive for cytokeratin markers K 5/14 and CD 44, as determined by confocal laser scanning microscopy. A small fraction of interdispersed single cells expressing c‐kit, which is found on pluripotent precursors, was identified by immunofluorescence. From these basal cells, in vitro differentiation of cells with neuroendocrine morphology could be achieved within 3 days. These were at rest, i.e., non‐bromodeoxyuridine incorporating cells and characteristically coexpressed K 5/14, K 18, and the neuroendocrine marker chromogranin A. Luminal cells staining for K 8 or 18 were not observed.

CONCLUSION

Neuroendocrine differentiation of adult prostatic cells was achieved in vitro, favoring the hypothesis that neuroendocrine cells are derived from peripheral precursor cells. The acceleration of this differentiation pathway may be the reason for the increased presence of neuroendocrine cells in areas of epithelial hyperplasia in BPH. Prostate 53: 101–108, 2002. © 2002 Wiley‐Liss, Inc.
Apoptosis resistance of neuroendocrine phenotypes in prostatic adenocarcinoma
Authors: Fixemer Thomas , Remberger Klaus , Bonkhoff Helmut
Published: October 2002

BACKGROUND

Neuroendocrine (NE) differentiation has been implicated in prostate cancer progression and hormone therapy failure. It has been shown that prostate cancer cells with NE features lack proliferation activity in vitro and in vivo. The current study reports on the apoptotic status of NE phenotypes in human prostate cancer.

METHODS

Double‐label techniques were used for simultaneous demonstration of the endocrine marker chromogranin A (ChrA) and DNA fragmentation assessed by the terminal transferase‐mediated biotinylated 16‐desoxy‐uridine‐tri‐phosphate (bio‐16‐dUTP) nick‐end‐labeling (TUNEL) assay. The material included primary prostatic adenocarcinoma (n = 18), lymph node metastases (n = 5), bone metastases (n = 2), and recurrent lesions (n = 10) showing NE differentiation at the immunohistochemical level.

RESULTS

Irrespective of grades, stages, and the degree of NE differentiation, DNA fragmentation was restricted to exocrine (ChrA‐negative) tumor cells and was undetectable in most of NE tumor cells expressing ChrA. At least 0.16% of ChrA‐positive tumor cells revealed DNA fragmentation assessed by the TUNEL assay.

CONCLUSION

The present data suggest that the vast majority of prostate cancer cells with NE features escapes programmed cell death. This escape may contribute significantly to their drug resistance and their malignant potential. Prostate 53: 118–123, 2002. © 2002 Wiley‐Liss, Inc.
Reduced plasma levels of coagulation factors in relation to prostate cancer
Authors: Beecken Wolf‐Dietrich , Bentas Wassilios , Engels Knut , Glienke Wolfgang , Urbschat Anja , Jonas Dietger , Binder Jochen , Scharrer Inge
Published: October 2002

BACKGROUND

Prostate cancer has historically been associated with coagulation abnormalities. This study was undertaken to investigate the prevalence of abnormalities of coagulation factors in patients with prostate cancer before and after radical prostatectomy (RP). Because coagulation factors have been shown to be involved in tumor angiogenesis, the vascular density of the prostate tumors was assessed.

METHODS

Plasma of 40 consecutive patients with histologically proven prostate cancer was investigated pre‐RP and post‐RP. The antigen level for antithrombin, plasminogen activator inhibitor‐1, and heparin cofactor‐II, and the plasma activity of antithrombin and plasminogen were determined by using immunologic and chromogenic assays. The values of these assays were compared with a group of 28 male, age‐matched patients without any evidence of cancer and 18 patients with orthopedic interventions preoperatively and postoperatively. The vascular density of the prostate tumors was assessed by staining paraffin sections with an antibody to CD34.

RESULTS

The median plasma antigen levels and/or activities of the investigated factors were below normal in the prostate cancer patients before RP. Furthermore, coagulation factors were significantly lower than in the age‐matched control group and patients before and after orthopedic surgery. In prostate cancer patients, the median values of all investigated factors went up to normal levels within 2 weeks after RP, whereas postsurgical levels in orthopedic patients remained stable. No correlations to tumor parameters have been observed.

CONCLUSION

We assume that the reduction of these coagulation factors is a principle concept in prostate cancer that needs further investigation. Prostate 53: 160–167, 2002. © 2002 Wiley‐Liss, Inc.
The value of power Doppler imaging to predict the histologic components of benign prostatic hyperplasia
Authors: Hayami Shinsuke , Ushiyama Tomomi , Kurita Yutaka , Kageyama Shinji , Suzuki Kazuo , Fujita Kimio
Published: October 2002

BACKGROUND

The response of symptoms caused by benign prostate hypertrophy (BPH) to alpha blockade is related to the area density of the smooth muscle of the prostate. If this density could be determined by ultrasound examination, ultrasound might be useful in predicting the efficacy of alpha‐blocker therapy. In this study, various ultrasonographic parameters obtained by transrectal method (TRUS) were compared with histologically measured components.

METHODS

Before surgery, ultrasonic power Doppler imaging (PDI) of the prostate was performed using a transrectal probe. The volume of total prostate, transition zone (TZ), and the presumed circle area ratio (PCAR) [1,2] were calculated. Pulsatile blood flow was recorded, and the resistive index (RI) was calculated. Based on the serum concentration of total prostate specific antigen (PSA), ratio of PSA to prostate volume (PSAD), and ratio of PSA to TZ (PSAT) were calculated. Prostate tissues were obtained from 26 patients undergoing transurethral resection, suprapubic prostatectomy, or radical cystectomy, and were analyzed by quantitative morphometry. Computer image analysis was used to determine the mean area densities of the smooth muscle (SM), connective tissue (CT), glandular epithelium (GE) and lumen (GL), and vascular lumen (V). Correlations between ultrasonographic parameters and morphometric data were studied.

RESULTS

On microscopic examination, the specimens showed a wide variety, ranging from normal prostate to typical glandular hyperplasia. There was a correlation between RI and the ratios of the four components (SM: r = −0.42 P = 0.034; CT: r = −0.42 P = 0.030; GE: r = 0.42 P = 0.032; GL: r = 0.46 P = 0.018). However, correlations between the other five transrectal parameters and the composition of the prostate were not so clear. This may have been because the blood vessels are compressed within the surgical capsule together with the urethra.

CONCLUSIONS

The present study demonstrates that when RI is calculated by PDI, it can be quite useful for predicting component ratios, thereby making it possible to predict the therapeutic efficacy of alpha‐blockers in individual patients. Prostate 53: 168–174, 2002. © 2002 Wiley‐Liss, Inc.
Influence of solvent molecules on the stereochemical code of glycyl residues in proteins
Authors: Eswar Narayanan , Nagarajaram H.A. , Ramakrishnan C. , Srinivasan N.
Published: October 2002

The Ramachandran steric map and energy diagrams of the glycyl residue are symmetric. A plot of (ϕ,ψ) angles of glycyl residues in 250 nonhomologous and high‐resolution protein structures is also largely symmetric. However, there is a clear aberration in the symmetry. Although there is a cluster of points corresponding to the right‐handed α‐helical region, the “equivalent” cluster is clearly shifted to in and around the (ϕ,ψ) values of (90°, 0°) instead of being centered at the left‐handed α‐helical region of (60°, 40°). This lack of symmetry exists even in the (ϕ,ψ) distribution of residues from non‐α‐helical regions in proteins. Here we provide an explanation for this observation. An analysis of glycyl conformations in small peptide structures and in “coil” proteins, which are largely devoid of helical and sheet regions, shows that glycyl residues prefer to adopt conformations around (±90°, 0°) instead of right‐ and left‐handed α‐helical regions. By using theoretical calculations, such conformations are shown to have highest solvent accessibility in a system of two‐linked peptide units with glycyl residue at the central Cα atom. This finding is consistent with the observations from 250 nonhomologous protein structures where glycyl residues with conformations close to (±90°, 0°) are seen to have high solvent accessibility. Analysis of a subset of nonhomologous structures with very high resolution (1.5 Å or better) shows that water molecules are indeed present at distances suitable for hydrogen bond interaction with glycyl residues possessing conformations close to (±90°, 0°). It is suggested that water molecules play a key role in determining and stabilizing these conformations of glycyl residues and explain the aberration in the symmetry of glycyl conformations in proteins. Proteins 2002;49:326–334. © 2002 Wiley‐Liss, Inc.
Allosteric effects of chloride ions at the intradimeric α1β1 and α2β2 interfaces of human hemoglobin
Authors: Rujan Iulian N. , Russu Irina M.
Published: October 2002

The structural transition induced by ligand binding in human hemoglobin encompasses quaternary structure changes at the interfaces between the two αβ dimers. In contrast, the interfaces between α and β subunits within the same dimer (i.e., α1β1 and α2β2 interfaces) are structurally invariant. Previous work from this laboratory using NMR spectroscopy has identified four sites at the intradimeric α1β1 and α2β2 interfaces that, although structurally invariant, experience significant changes in the rates of proton exchange upon ligand binding. These sites are Hisα103(G10) and Hisα122(H5) in each α subunit of the hemoglobin tetramer. In the present work, we show that the proton exchange at the Hisα103(G10) sites is affected by the interactions of hemoglobin with chloride ions. Increasing concentrations of chloride ions at pH 6.45 and at 37°C enhance the exchange rate of the Hisα103(G10) Nε2 proton. The enhancement is greater in deoxygenated than in ligated hemoglobin. In the framework of the local unfolding model for proton exchange, these results suggest that the structural free energy and/or the proton transfer reactions at the Hisα103(G10) sites depend on the concentration of chloride ions. Therefore, the ligand‐induced changes at the Hisα103(G10) sites are modulated by the allosteric effect of chloride ions on hemoglobin. Proteins 2002;49:413–419. © 2002 Wiley‐Liss, Inc.
Emamectin, a novel insecticide for controlling field crop pests
Authors: Ishaaya Isaac , Kontsedalov Svetlana , Horowitz A Rami
Published: October 2002

Emamectin is a macrocyclic lactone insecticide with low toxicity to non‐target organisms and the environment, and is considered an important component in pest‐management programmes for controlling field crop pests. It is a powerful compound for controlling the cotton bollworm Helicoverpa armigera (Hübner). A spray concentration of 25 mg AI litre−1 in a cotton field resulted in over 90% suppression of H armigera larvae up to day 28 after treatment, while similar mortality of the Egyptian cotton leafworm Spodoptera littoralis Boisduval, under the same conditions, was maintained for 3 days only. Emamectin is a potent compound for controlling the western flower thrips Frankliniella occidentalis (Pergande) under both laboratory and field conditions and its activity on adults was over 10‐fold greater than that of abamectin. Spray concentrations of 10 and 50 mg AI litre−1 in Ageratum houstonianum Mill flowers resulted in total suppression of adults up to day 11 and of larvae up to day 20 after treatment. Under standard laboratory conditions, emamectin exhibits a considerable activity on the whitefly Bemisia tabaci (Gennadius) and the leafminer Liriomyza huidobrensis (Blanchard). Further studies are required to evaluate its potential activity on the latter pests under field conditions.

© 2002 Society of Chemical Industry
Dynamics of insecticide resistance in Bemisia tabaci: a case study with the insect growth regulator pyriproxyfen
Authors: Horowitz A Rami , Kontsedalov Svetlana , Denholm Ian , Ishaaya Isaac
Published: October 2002

The dynamics of pyriproxyfen resistance in Bemisia tabaci (Gennadius) have been studied intensively in cotton fields and greenhouses in Israel. High resistance to pyriproxyfen evolved one year after its introduction for use on flowers in greenhouses, after three successive applications. After ten years of pyriproxyfen use in cotton fields, with only one application per season, a high level of resistance was observed, but its rate of development differed among localities. It is hypothesized that these differences reflect temporal and spatial variations in the availability of alternative host plants for B tabaci, and that pyriproxyfen resistance evolved most readily in geographically isolated areas. It is also likely that the occurrence and development of resistance is partially biotype‐related. Pyriproxyfen use has ceased in high‐resistance localities, but in areas with low frequencies of resistance, cotton growers have continued to achieve acceptable control of B tabaci with pyriproxyfen. Due to the absence of applications of pyriproxyfen in some cotton fields, resistance levels tended to decline between 1998 and 2001. Laboratory experiments support the hypothesis that this decline reflects, in part, fitness costs associated with pyriproxyfen resistance.

© 2002 Society of Chemical Industry
A comparative study of different crude extracts of Ocimum sanctum on noise stress
Authors: Archana R. , Namasivayam A.
Published: October 2002

Our previous studies have shown that the ethanolic extract of Ocimum sanctum (OS) leaves was effective in alleviating the noise stress induced changes. Hence in this study, we have investigated the effectiveness of different types of crude OS extracts on some of the stress parameters after noies stress. The results of this study has shown that the active pinciple responsible for antistressor effect of ethanolic extract is also present in cold homogenised leaf extract of OS also. Hot extracts slightly decrease the potency of the active principle in normalizing corticosteroid level. Copyright © 2002 John Wiley & Sons, Ltd.
Keishi‐bukuryo‐gan preserves the endothelium dependent relaxation of thoracic aorta in cholesterol‐fed rabbit by limiting superoxide generation
Authors: Sekiya Nobuyasu , Goto Hirozo , Tazawa Kenji , Oida Shoko , Shimada Yutaka , Terasawa Katsutoshi
Published: October 2002

Formerly, we have reported that keishi‐bukuryo‐gan prevents the progression of atherosclerosis in cholesterol‐fed rabbits and inhibits the free radical‐induced RBC haemolysis in rats.

The present study was performed to investigate how keishi‐bukuryo‐gan (KBG) inhibits the early stage of atherosclerosis. Plasma lipid concentration and hydroxyl radical generation during respiratory burst in neutrophils were evaluated at the start and end of the study. The protective effect of KBG against endothelium disorder due to hypercholesterolaemia was examined. Twelve male Japanese white rabbits (2 kg body weight) were divided into two groups. Group A (n = 6) was fed standard rabbit chow containing 1% cholesterol for 4 weeks. Group B (n = 6) was fed standard rabbit chow containing 1% cholesterol and 1% KBG for 4 weeks. In the plasma lipid concentration, only the lipid peroxide concentration of group A was significantly higher than that of group B. At the end of the study, DMPO‐OH, the spin‐trapped adduct of hydroxyl radicals generated by neutrophils, was increased in both groups, and this increase was marked in group B. Endothelium‐dependent vasodilatation by acetylcholine increased significantly in group B compared with group A. Thus, KBG protects the vascular endothelium function by its antioxidative effect and by inhibiting the release of free radicals from neutrophils in vivo. Copyright © 2002 John Wiley & Sons, Ltd.
Combining preventive replacement and burn‐in procedures
Authors: Drapella Antoni , Kosznik Sylwia
Published: October 2002

This paper considers a non‐homogeneous population of items. Most of the items fail due to a wear‐out process. Therefore it is reasonable to employ a procedure of preventive maintenance. Some items, however, are of short life due to intrinsic defects. When used as replacement parts they may spoil results of planned prevention. The paper seeks for equilibrium of burn‐in and preventive replacement periods. Copyright © 2002 John Wiley & Sons, Ltd.
Partition experimental designs for sequential processes: Part II—second‐order models
Authors: Perry Leonard A. , Montgomery Douglas C. , Fowler John W.
Published: October 2002

Second‐order experimental designs are employed when an experimenter wishes to fit a second‐order model to account for response curvature over the region of interest. Partition designs are utilized when the output quality or performance characteristics of a product depend not only on the effect of the factors in the current process, but the effects of factors from preceding processes. Standard experimental design methods are often difficult to apply to several sequential processes. We present an approach to building second‐order response models for sequential processes with several design factors and multiple responses. The proposed design expands current experimental designs to incorporate two processes into one partitioned design. Potential advantages include a reduction in the time required to execute the experiment, a decrease in the number of experimental runs, and improved understanding of the process variables and their influence on the responses. Copyright © 2002 John Wiley & Sons, Ltd.
Autocorrelated process monitoring using triggered cuscore charts
Authors: Shu Lianjie , Apley Daniel W. , Tsung Fugee
Published: October 2002

Some of the most widely‐investigated control charting techniques for autocorrelated data are based on time series residuals. If the mean shift in the autocorrelated process is a sudden step shift, the resulting mean shift in the residuals is time varying and has been referred to as the fault signature. Traditional residual based charts, such as a Shewhart, CUSUM, or EWMA on the residuals, do not make use of the information contained in the dynamics of the fault signature. In contrast, methods such as the Cuscore chart or Generalized Likelihood Ratio Test (GLRT) do incorporate this information. In order for the Cuscore chart to fully benefit from this, its detector coefficients should coincide with the fault signature. This is impossible to ensure, however, since the exact form of the fault signature depends on the time of occurrence of the mean shift, which is generally not known a priori. Any mismatch between the detector and the fault signature will adversely affect the Cuscore performance. This paper proposes a CUSUM‐triggered Cuscore chart to reduce the mismatch between the detector and fault signature. A variation to the CUSUM‐triggered Cuscore chart that uses a GLRT to estimate the mean shift time of occurrence is also discussed. It is shown that the triggered Cuscore chart performs better than the standard Cuscore chart and the residual‐based CUSUM chart. Examples are provided to illustrate its use. Copyright © 2002 John Wiley & Sons, Ltd.
INDO/S parameters for gold
Authors: Shapley Warwick A. , Reimers Jeffrey R. , Hush Noel S.
Published: October 2002

Two INDO/S parameter sets, designed for use in conjunction with 6s and 6s+6p+5d basis sets, have been determined for gold. These basis sets are comprised of Slater‐type orbitals with exponents chosen to best reproduce the radial expectation values r, r2, and r3 of the gold Hartree–Fock atomic orbitals. The adjustable parameters in the model were optimized to maximize agreement with experimental atomic ionization potentials and electron affinities, molecular ionization potentials and dipole moments obtained using density‐functional theory, and molecular excitation energies obtained using multireference configuration interaction methods. For the 6s basis, the optimal value of the (only) freely adjustable parameter βs is −2.5 eV while for the larger basis we determine βs=−4.0 eV and βd=−50.0 eV. We find the small basis set to be most appropriate for calculations on very large clusters and for dipole moment analysis, while the large basis is most appropriate for small complexes and spectral simulation. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Calculation of matrix elements in relativistic quantum mechanics
Authors: Ilarraza‐Lomelí A. C. , Valdés‐Martínez M. N. , Salas‐Brito A. L. , Martínez‐y‐Romero R. P. , Núñez‐Yépez H. N.
Published: October 2002

Employing a relativistic version of a hypervirial result, recurrence relations for arbitrary nondiagonal radial hydrogenic matrix elements have recently been obtained in Dirac relativistic quantum mechanics. In this contribution honoring Professor Löwdin, we report on a new relation we have recently discovered between the matrix elements 〈2∣rλ∣1〉 and 〈2∣βrλ∣1〉—where β is a Dirac matrix and the numbers distiguish between different radial eigenstates—that allow for a simplification and hence for a more convenient way of expressing the recurrence relations. We additionally derive another relation that can be employed for simplifying two‐center matrix element calculations in relativistic atomic or molecular calculations. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
Ab initio calculations and modeling of three‐body forces in Ar2H2O
Authors: Burcl Rudolf , Szczȩśniak M. M. , Kłos Jacek , Chałasiński Grzegorz , Cybulski Sławomir M.
Published: October 2002

The nonadditive interactions in the Ar2H2O cluster, in a variety of geometries, are studied using the supermolecular Møller–Plesset (MP) perturbation theory in conjunction with the perturbation theory of intermolecular forces. The three‐body effect is dissected into several components: the Heitler–London exchange, induction, dispersion, and second‐order supermolecular MP perturbation nonadditivity. The latter term is further analyzed within the framework of pseudodimer treatment. The Heitler–London exchange is dissected into the SE (single exchange) and TE (triple exchange) parts. Analytical representations of the nonadditive terms are discussed. For the exchange (SE) and induction, the multicenter expansions work very well. However, in the case of the three‐body dispersion term, the single‐center dipole‐dipole‐dipole plus dipole‐dipole‐quadrupole expression proves to be more suitable. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Ab initio calculations and modeling of three‐dimensional adiabatic and diabatic potential energy surfaces of F(2P)···H2(1Σ+) Van der Waals complex
Authors: Kłos Jacek , Chałasiński Grzegorz , Szczȩśniak M. M.
Published: October 2002

Three lowest diabatic potential energy surfaces for the F(2P) + H2 Van der Waals complex are derived from accurate ab initio calculations of the T‐shaped (C2v) and collinear geometries (C∞v), at the coupled‐cluster single, double, and noniterative triple excitations [CCSD(T)] level of theory with a large basis set. For the intermediate geometries the angular dependence is modeled by a simple Legendre‐polynomial interpolation. The nonadiabatic coupling (off‐diagonal derivative) matrix element, and the fourth, off‐diagonal, diabatic surface are determined by separate multireference configuration interaction (MR‐CI) calculations with a somewhat smaller basis set. Three adiabatic potential energy surfaces (PESs) are also obtained, by diagonalizing the total Hamiltonian in the diabatic basis. Both the nonrelativistic and relativistic (including spin‐orbit coupling) PESs are evaluated. They are found to be in very good agreement with the entrance channel of the ASW PESs (Alexander, Manolopoulos, and Werner, J Chem Phys 2000, 113, 11084). The dependence of the PESs on the H2 stretching coordinate is also incorporated and analyzed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Artificial molecules
Authors: Jaskólski W. , Bryant G. W. , Planelles J. , Zieliński M.
Published: October 2002

Double semiconductor nanocrystals, called artificial molecules by analogy to artificial atoms (quantum dots), are investigated. Empirical tight‐binding and k · p theories are used to obtain electronic structure, charge density distributions, and optical absorption spectra for single and double nanocrystals. We show how the bonding and antibonding molecular orbitals are formed from the wavefunctions of individual nanocrystals when the nanocrystals are joined together to form an artificial molecule. Formation of quantum dot lattices and interpretation of experimental data for close‐packed solids of nanocrystals are discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Partitioning technique and transport across molecular interfaces: Many‐body effects
Authors: Mujica Vladimiro , Ratner Mark A. , Goscinski Osvaldo
Published: October 2002

We review the theory of transport across molecular interfaces within the framework of the partitioning and inner projection techniques, developed by Per‐Olov Löwdin. Using a one‐particle approximation to the many‐body equation for the current in a system consisting of a molecular bridge and two electrodes, it is shown that the idea of partitioning can be used advantageously to define a self‐energy that contains the coupling of the molecule to the electrodes. Inner projections are then introduced as a systematic way of including electron correlation effects in the transport across molecular junctions. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
On the interaction between manganese cation (Mn2+) and the nucleic acid bases (T, U, C, A, G) in the gas phase
Authors: Russo Nino , Sicilia Emilia , Toscano Marirosa , Grand Andrè
Published: October 2002

The coordination modes, the equilibrium geometrical structures, and the gas‐phase metal ion affinity for the Mn2+ metal cation interacting with uracil, thymine, cytosine, adenine, and guanine were determined considering different low energy tautomers for the free nucleic acid bases and by using the density functional theory. For uracil and thymine, the mono‐coordinated complexes coming from the metalation of the oxo tautomers are not minima, whereas the manganese ion forms stable compounds with high energy tautomers for which the bi‐coordination is possible. Also for cytosine, adenine, and guanine the bi‐coordination is the favored binding mode. Despite the cytosine and guanine free bases have different tautomers lying in a very narrow range of energy, the stabilities of the corresponding metalated complexes differ significantly. A reverse situation occurs for uracil and thymine for which we obtain manganese complexes of comparable stability, while the tautomeric forms of the isolated free bases are well separated in energy. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Cumulant 2‐matrix of the high‐density electron gas and the density matrix functional theory
Authors: Ziesche P.
Published: October 2002

The cumulant 2‐matrix χ is that part of the two‐body reduced density matrix γ2, which cannot be reduced to products of the one‐body reduced density matrix (1‐matrix) γ. This irreducible part χ is calculated perturbatively for the high‐density electron gas (EG) in its ground state, such that the pair densities and the interaction energy are correctly reproduced in their high‐density limits, which are exactly known and summarized here. From the thus available cumulant 2‐matrix the pair density in momentum space can be derived and used for a fluctuation analysis and compared with the analog analysis in position space, where it is concluded that “correlation suppresses fluctuations”. The perturbatively available cumulant 2‐matrix χ can be used also for the high‐density electron gas to start the iterative solution of the Yasuda integral equation of density matrix functional theory (DMFT), which is a nonlinear functional relation between the cumulant 2‐matrix χ and the 1‐matrix γ recently derived from the contracted Schrödinger equation approach: χY[γ]. From the perturbatively determined χ one can find another functional χ[γ] as an alternative approximation for a DMFT. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Theoretical ab initio study of ranitidine
Authors: Martins Jão B. L. , Perez Marco A. , Silva Carlos H. T. P. , Taft C. A. , Arissawa M. , Longo Elson , Mello P. C. , Stamato Fulvia M. L. G. , Tostes J. G. R.
Published: October 2002

The presence of a heterocyclic ring containing a basic center linked via a methylene chain to a substituted guanidine or thiourea polar side chain, such as found in the H2‐antagonist metiamide, which has an imidazole heterocyclic ring, has often been identified as one of the requirements for H2‐antagonist activity. In ranitidine, on the other hand, the imidazole ring is substituted for a furan ring, yielding a more active biological H2 antagonist. In this work, we have used the ab initio Hartree–Fock (HF) and second‐order Møller–Plesset (MP2) methods in order to investigate the open and folded ranitidine conformations, of the type observed in metiamide. Five basis sets (3‐21G, 3‐21+G**, 6‐31G, 6‐31+G**, and 6‐31+G**) were used in order to obtain fully optimized geometric parameters that indicated good agreement with the experimental crystallographic data. We have also investigated in this work the effects of solvents in both ranitidine and metiamide. Monocationic ranitidine was also investigated. All our results, indicate that, as in metiamide, the folded conformation is also preferred. We have investigated Mulliken and natural bond order (NBO) charge distributions, electrostatic and hydrogen bond effects on stabilizing the conformations and discussed the interactions of ranitidine with the biological receptor. © 2002 John Wiley & Sons, Inc. Int J Quantum Chem, 2002
A rapid and efficient mass spectrometric method for the analysis of explosives
Authors: Evans C. S. , Sleeman R. , Luke J. , Keely B. J.
Published: October 2002

The high explosives trinitrotoluene, nitroglycerine, pentaerythritol tetranitrate and hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine are efficiently ionised under negative ion atmospheric pressure chemical ionisation (APCI) conditions. The limit of detection is improved, in some cases by several orders of magnitude, by complexation with chlorine demonstrating this to be a highly suitable method for enhancing the detection capabilities for explosives. The spectra produced from introduction of the analytes in a liquid matrix, with and without chlorine present, contain a number of ions that arise through secondary processes including breakdown and adduct formation. Sample introduction into an APCI source in air, via a heated‐plate inlet with a supplementary feed of dichloromethane, produces improved response for the chloride adducts of the analytes and minimises their decomposition during analysis. The tandem mass spectra produced from the chloride adducts are simple. Optimisation of the trapping parameters of the ion trap detector enhances selected transitions, yields highly reproducible spectra and improves the limits of detection for MS/MS analysis. Copyright © 2002 John Wiley & Sons, Ltd.
On the detailed mechanisms of collision‐induced dissociation experiments performed by electrospray ion trap
Authors: Catinella Silvia , Pelizzi Nicola , Barboso Silvia , Favretto Donata , Seraglia Roberta , Traldi Pietro
Published: October 2002

The product ion spectra obtained by electrospray ionization (ESI) ion trap instruments exhibit a higher number of fragment ions than those achieved by other ion‐trap‐based systems, indicating the presence of more effective energy deposition mechanisms. This behavior can be attributed to several different reasons, among which different initial internal energy of the precursor ions, pre‐activation due to collisions taking place outside the trap, different target gas mixtures inside the trap, and different ion trap geometry were considered. Data obtained from experiments using a triple quadrupole instrument, CI‐ion trap, and ESI‐ion trap have been compared. The results so achieved seem to indicate that the presence inside the trap of neutral molecules of the solvent employed for the ESI process have a relevant role, promoting high energy deposition in the colliding ions. Copyright © 2002 John Wiley & Sons, Ltd.
Rapid analysis of intact phospholipids from whole bacterial cells by matrix‐assisted laser desorption/ionization mass spectrometry combined with on‐probe sample pretreatment
Authors: Ishida Yasuyuki , Madonna Angelo J. , Rees Jon C. , Meetani Mohammed A. , Voorhees Kent J.
Published: October 2002

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), utilizing an on‐probe sample pretreatment, was applied to the rapid and direct detection of intact phospholipids from whole bacterial cells. The sample preparation procedure involved depositing growing bacterial colonies from culture dishes directly onto the MALDI probe followed by treatment of the sample spot with a 3 µL aliquot of an aqueous 0.05 M solution of sodium iodide prior to the addition of a 2,5‐dihydroxybenzoic acid (DHB) matrix solution (ca. 8 mg dissolved in 70% acetonitrile/30% H2O containing 0.1% of trifluoroacetic acid). The MALDI spectra obtained from whole bacteria cells showed a series of ions generated from bacterial phospholipids, such as phosphatidylethanol‐amines (PEs) and phosphatidylglycerols (PGs), which were clearly observed as well‐resolved peaks. The ranges of the observed total carbon numbers in two acyl groups for PEs and PGs (30–36 and 33–36, respectively) were in good agreement with those reported previously. Furthermore, the distinct discrimination of four species of the Enterobacteriaceae family cultured identically was achieved by using principal components analysis (PCA) conducted on the relative peak intensities of phospholipids observed from the MALDI spectra. Copyright © 2002 John Wiley & Sons, Ltd.
Selected ion flow tube studies of the reactions of H3O+, NO+ and O2+ with the anaesthetic gases halothane, isoflurane and sevoflurane
Authors: Wang Tianshu , Smith David , Španěl Patrik
Published: October 2002

We have carried out a study of the reactions of H3O+, NO+ and O2+, the commonly used precursor ions for selected ion flow tube mass spectrometry (SIFT‐MS), with three anaesthetic gases, halothane, isoflurane and sevoflurane. The motivation for this study was to provide the necessary kinetic data that would allow the quantification of these anaesthetic gases in operating theatre air and in the breath of theatre staff and post‐operative patients. A clear negative result from these experiments is that NO+, although undergoing the simplest chemistry, is unsuitable for this SIFT‐MS application. However, although the ion chemistry of H3O+ and O2+ with these compounds is very complex, there being several product ions in each reaction, many of which react rapidly with water molecules, monitor ions have been identified for all three anaesthetic gases when using H3O+ and O2+ as precursor ions. The detailed ion chemistry is discussed and the specific monitor ions are indicated. Hence, the feasibility of on‐line breath monitoring is demonstrated by simple examples. These studies have opened the way to measurements in the clinical environment. Copyright © 2002 John Wiley & Sons, Ltd.
Visualizing reductive dechlorination in support of intrinsic bioremediation using multivariate plots and GIS
Authors: Seagren Eric A. , Clarke Raymond , Johnson Mark
Published: October 2002

Demonstrating intrinsic bioremediation requires not only that the right types of evidence be gathered, but
also that those data be analyzed at an appropriate level of detail and presented in a manner that clearly
illustrates the key trends to the target audience. The goal of this study was to develop one type of multivariate
pattern diagram, the pie diagram, for clearly and efficiently presenting data demonstrating the occurrence of
reductive dechlorination at sites contaminated by chlorinated ethenes. The pie diagrams were created using
normalized ethenes molar concentrations to estimate and illustrate the changes in the concentrations of
contaminants and metabolic intermediates that could be attributed to biodegradative processes. Spatial
pie‐diagram maps illustrating the normalized chlorinated‐ethenes data were produced using
geographic information system (GIS) software. Application of this visualization tool is demonstrated
using an example data set and is compared with a conventional x‐y graph of the data. The trends elucidated
on the basis of the pie diagrams, coupled with additional site evidence of natural attenuation (e.g.,
electron donor and acceptor data), are shown to provide a consistent interpretation of the site data. ©
2002 Wiley Periodicals, Inc.
Evaluation of a soil‐amendment process demonstration for reducing the bioavailability of lead
Authors: Barth Edwin F. , Evans Mark
Published: October 2002

The U.S. Environmental Protection Agency (EPA) evaluated an in‐situ application of a
soil‐amendment process at a residential site that was contaminated with lead. The goal of the evaluation
was to determine if the soil‐amendment process resulted in lower concentrations of bioavailable lead in the
contaminated soils. The relative bioavailability of lead (bioaccessible lead) was measured by an in
vitro test procedure that uses a highly acidic extraction procedure to simulate human digestive processes. The
soil‐amendment demonstration showed that the 11.2 percent mean reduction in bioavailable lead concentration
between untreated and treated soils was not statistically different. © 2002 Wiley Periodicals, Inc.
Reducing salinity and organic contaminants in the Pearl Harbor dredged material using soil amendments and plants
Authors: Hue N. V. , Campbell S. , Li Q. X. , Lee C. R. , Fong J.
Published: October 2002

Phytoremediation is an emerging technique that can be used to economically remediate sites contaminated with
trace elements and/or man‐made organic contaminants. This technique was used on Pearl Harbor (Oahu,
Hawaii) dredged material (PHDM) containing polycyclic aromatic hydrocarbons (PAHs) and
some heavy metals. The dredged material was first amended with a high‐calcium soil (Waialua
Mollisol) and a biosolids‐based compost at different proportions to yield varying salinity levels. A
mixture that yielded an electrical conductivity (EC, a measure of salinity) of the saturated paste
extract of 15 to 20 dS/m was identified and used to evaluate the salt tolerance of five plant species. Relative
germination and one‐month‐old biomass indicated that common bermuda grass (Cynodon
dactylon), seashore paspalum (Paspalum vaginatum), beach pea
(Vigna marina), and cow pea (Vigna unguiculata) can produce
at least 40 percent of biomass of the control at an EC of approximately 18 dS/m, suggesting the four plants are
relatively salt tolerant. In contrast, Desmodium intortum either did not germinate or died within
two weeks after germination at the same salinity level. A subsequent greenhouse experiment, using mixtures of the
PHDM (0 or 25 percent dry weight), organic amendments (10 percent leucaena green manure or
biosolids‐based compost), and a Mollisol (65 or 90 percent dry weight) in 6‐liter pots
containing 4 kilograms of material yielded the following results: (1) A combination of transplanted
seashore paspalum, seeded bermuda grass, and seeded beach pea was effective in taking up sodium (Na),
thereby reducing salinity and making the medium more amenable to diversified microbes and plants, which may be
effective PAH degraders; (2) total PAH concentration was reduced by about 30 percent after three
months of active plant growth, but degradation of individual PAH members varied significantly, however;
(3) leguminous green manure, as a soil amendment, was more effective than compost for use in bio‐
and/or phytoremediations; and (4) soil amendments, when applicable, could supplement living
plants in reducing organic contaminants, such as PAHs. © 2002 Wiley Periodicals, Inc.