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PubMed2003

Determination of dermal absorption QSAR/QSPRs by brute force regression: multiparameter model development with Molsuite 2000.

Accurate dermal quantitative structure-activity/property relationship (QSAR/QSPR) models are needed to predict percutaneous absorption of environmental contaminants. The Molsuite 2000 chemistry modeling software (ChemSW, Fairfield, CA) was used to model the Flynn component of the Kirchner in vitro human skin permeability coefficient (K(p)) data. This Kirchner- derived Flynn (K/F) database was updated to include recent literature data quality recommendations. A K/F data subset consisting of nondrug compounds was used to further optimize the developed QSPR models. The statistical fit of the models was excellent with r(2) values up to.89 for a three-descriptor parameter K/F database model and up to.96 for a four- parameter model of the data subset. A one-parameter transform model using only logarithm octanol-water partition coefficient (log K(o/w)) was also developed for the data subset (r(2) =.87). Molecular volume (MV) descriptors were not shown to be superior to molecular weight in conventional two-parameter models with log K(o/w) but may be superior in multiparameter models. A previously nonreported descriptor, surface tension in water (STW), was found to provide optimal multiparameter models. The developed models passed PRESS cross-validation and could be useful for predicting environmental systemic dermal exposure.

Databases, Factual↗
PubMed1994

Project Wildfish: rewarding through innovation.

The appropriateness of a reward system depends, in part, on the developmental level of the staff. Based on a model developed at Shadyside Hospital, Pittsburgh, PA, called the Transformational Model for the Practice of Professional Nursing, we have determined that the potential for innovation becomes a highly valued reward for a healthy, well-developed nursing unit. Project Wildfish illustrates the energy, commitment, and enthusiasm that innovation can inspire.

Clinical Nursing Research↗
PubMed1984

Educating the nursing profession for role transformation.

This article proposes the use of a role transformation model to facilitate the assumption of more progressive attitudes and more autonomous, responsible behavior by nurses. Five major areas of content which need to be addressed in the role transformation process are detailed: 1) Defining and Articulating the Nursing Domain, 2) Legitimizing the Nursing Profession, 3) Communicating in Professional rather than Non-professional Modes, 4) Negotiating Collaborative Roles, and 5) Cultivating the Organizational Network. Emphasis is placed on the responsibility of nursing educators to model and facilitate role transformation for students and nursing colleagues.

Communication↗
PubMed2004

Agrobacterium-mediated transformation of the wetland monocot Typha latifolia L. (Broadleaf cattail).

An Agrobacterium-mediated model transformation system was standardized for the wetland monocot Typha latifolia L. to achieve the long-term objective of introducing candidate genes for phytoremediation. Two binary plasmid vectors, pCAMBIA1301/EHA105 and pTOK233/LBA4404, both containing the gus (beta-glucuronidase) and hptII (hygromycin phosphotransferase II) genes, were used for transformation. Fifty-day-old 5 mg/l picloram-derived calli were cocultivated and selected on medium containing 20 mg/l or 40 mg/l hygromycin. Resistant calli were regenerated on medium supplemented with 5 mg/l 6-benzylaminopurine, with or without 20 mg/l or 40 mg/l hygromycin and with or without charcoal (10 g/l). Transient GUS activity in explants ranged between 28% and 36%. Hygromycin-resistant calli, selected after 3 months, showed stable GUS expression. A total of 46 plants were regenerated and established in the greenhouse; 13 showed stable GUS expression. Cocultivation of dark culture-derived calli, directly selected on regeneration medium containing 20 mg/l hygromycin and rooted on medium with 20 mg/l hygromycin was the best protocol. The addition of charcoal did not have any effect on regeneration. PCR and Southern analyses of transgenic calli and transgenic plants confirmed the presence of the introduced genes. In conclusion, T. latifolia could be genetically transformed by Agrobacterium tumefaciens.

Blotting, Southern↗
PubMed1997

Grafting assay distinguishes promotion sensitive from promotion resistant JB6 cells.

The JB6 mouse epidermal cell system has been used extensively as an in vitro transformation model for the study of tumor promotion. The standard JB6 cell assay for promotion of transformation is carried out in soft agar or other anchorage independent conditions. The present study was directed to the development of an in vivo model to distinguish the promotion resistant (P-) and promotion sensitive (P+) progression phenotypes. Results indicate that the grafting assay distinguishes P- and P+ cells in vivo with P+ but not P- cells forming tumors within 7-9 weeks. Expression of dominant negative mutant jun TAM67 blocks both anchorage independent transformation response and graft bed tumor formation by P+ cells, suggesting that the requirement for AP-1 activation in transformation now applies in vivo. Expression of mutated p53 produced a gain of P+ phenotype in P- cells in vitro, but not in vivo. Histochemical and Northern blot analysis for expression of various keratinocyte markers revealed no evidence for expression, suggesting a loss of keratinocyte markers following establishment in culture. In summary, the skin-grafting assay described in this study appears to be a valid in vivo assay for distinguishing the preneoplastic progression phenotypes represented by JB6 P- and P+ cells.

Animals↗
PubMed1999

Mesoscopic model for the viscosities of nematic liquid crystals.

Based on the definition of the mesoscopic concept by Blenk et al. [Physica A 174, 119 (1991); J. Noneq. Therm. 16, 67 (1991); Mol. Cryst. Liq. Cryst. 204, 133 (1991)] an approach to calculate the Leslie viscosity coefficients for nematic liquid crystals is presented. The approach rests upon the mesoscopic stress tensor, whose structure is assumed similar to the macroscopic Leslie viscous stress. The proposed form is also the main dissipation part of the mesoscopic Navier-Stokes equation. On the basis of the correspondence between microscopic and mesoscopic scales a mean-field mesoscopic potential is introduced. It allows us to obtain the stress tensor angular velocity of the free rotating molecules with the help of the orientational Fokker-Planck equation. The macroscopic stress tensor is calculated as an average of the mesoscopic counterpart. Appropriate relations among mesoscopic viscosities have been found. The mesoscopic analysis results are shown to be consistent with the diffusional model of Kuzuu-Doi and Osipov-Terentjev with the exception of the shear viscosity alpha(4). In the nematic phase alpha(4) is shown to have two contributions: isotropic and nematic. There exists an indication that the influence of the isotropic part is dominant over the nematic part. The so-called microscopic stress tensor used in the microscopic theories is shown to be the mean-field potential-dependent representation of the mesoscopic stress tensor. In the limiting case of total alignment the Leslie coefficients are estimated for the diffusional and mesoscopic models. They are compared to the results of the affine transformation model of the perfectly ordered systems. This comparison shows disagreement concerning the rotational viscosity, whereas the coefficients characteristic for the symmetric part of the viscous stress tensor remain the same. The difference is caused by the hindered diffusion in the affine model case.

Journal Article↗
PubMed1998

A stochastic model of cellular transformation and its relevance to chemical carcinogenesis.

A mathematical model is presented which determines the relationship of cellular mutation to cellular survival and transformation. The basis for this model is the hypothesis that the entropy associated with changes of genotype are linearly proportional to the entropy associated with changes in phenotype. This hypothesis leads to a mathematical derivation relating cellular survival, mutation and transformation. The relevance of this model to data derived from experiments in chemical carcinogenesis is presented.

Animals↗
PubMedDate not supplied

Seasonal change in nutritional status among young children in an urban shanty town in Peru.

Seasonal variation in nutritional status among young children has been described in rural populations, but in few urban settings. We examined seasonality in 7 years of nutritional surveillance data from an urban shanty town near Lima, Peru, where children 0-35 months old were measured at intervals of 4-5 months. We compared nutritional status by month, using generalized estimating equations to account for the intercorrelations among measurements of the same person at different times. The periodicity of the seasonal variation was found to fit a model in which the month of the year was sine-transformed, and this sine-transformed model was used to examine possible interactions with age, sex and year of examination. A total of 38,626 measurements was available from 11,333 children. In late winter, mean weight-for-height was an estimated 0.38 Z score higher than in late summer. The seasonal effect occurred at all ages, in both sexes, and in each year of surveillance. The amplitude was greatest for children 6-23 months old. The summer trough in weight-for-height was lower in 1989 than in other years; children who experienced this summer low had lower mean height-for-age in subsequent years. The seasonal variation in nutritional status may be related to differences in dietary intake, or to the higher prevalence of bacterial diarrhoea in summer than in winter. The more marked drop in weight-for-height in 1989 and subsequent trough in height-for-age may be related to political and economic changes than adversely affected food access in Peru.

Body Height↗
PubMed1994

Nonrandom cytogenetic changes accompany malignant progression in clonal lines abelson virus-infected lymphocytes.

Initially, lymphoid cells transformed by v-abl or BCR/ABL oncogenes are poorly oncogenic but progress to full transformation over time. Although expression of the oncogene is necessary to initiate and maintain transformation, other molecular mechanisms are thought to be required for full transformation. To determine whether tumor progression in ABL oncogene-transformed lymphoid cells has a genetic basis, we examined whether progression of the malignant phenotype of transformed clones correlates with particular cytogenetic abnormalities. A modified in vitro bone marrow transformation model was used to obtain clonal Abelson murine leukemia virus-transformed B lymphoid cells that were poorly oncogenic. Multiple subclones were then derived from each clone and maintained over a marrow-derived stromal cell line for several weeks. Over time, clonally related Abelson murine leukemia virus-transformed subclones progressed asynchronously to full transformation. The data show that tumor progression can occur in the absence of detectable cytogenetic changes but, more importantly, that certain cytogenetic abnormalities appear reproducibly in highly malignant subclones. Therefore, three independent subclones showed deletion in a common region of chromosome 13. Other highly malignant cells carried a common breakpoint in the X chromosome, and, finally, two subclones carried an additional chromosome 5. These results are consistent with the hypothesis that ABL oncogenes are sufficient for the initial transformation of cells but that additional genetic events can drive oncogenic progression. These observations further suggest that diverse genetic mechanisms may be able to drive tumor progression in cells transformed with ABL oncogenes.

Abelson murine leukemia virus↗
PubMed2004

Inhibition of neoplastic transformation of benzo[alpha]pyrene-treated BALB/c 3T3 murine cells by a phytochemical extract of passionfruit juice.

The phytochemical composition of passionfruit juice (PFJ) was hypothesized to have valuable anti-cancer activity, and this was tested in a BALB/c 3T3 neoplastic transformation model. A higher concentration of PFJ compared with a lower concentration was effective in reducing the number, size, and invasiveness of transformed foci. When incubated with another mammalian cell line, the MOLT-4, PFJ was unable to alter the cell cycle kinetics while at the same time was successful in inducing the activity of caspase-3, an enzyme that commits the cell to apoptosis. This suggests that phytochemicals found in PFJ were able to produce the changes in transformed foci due to apoptotic mechanisms rather than by a reduction in cell proliferation. These beneficial results were achieved at levels that could theoretically be attained in the plasma after consumption of the juice.

3T3 Cells↗
PubMed2001

Testing a multimedia compartmental model with monitoring data.

Based on its geographic similarity and nested structure, a chemical transport and transformation model developed in The Netherlands was adopted to a nine-parish, 5,400-km2 area in southern Louisiana, USA, and tested for its ability to predict concentrations in the environment. SimpleBox 2.0 represents a class of models that compartmentalize the air, water, soil, sediment, and plants into boxes while maintaining a high degree of detail for processes within and between boxes. Past use has been in the evaluative mode, primarily where qualitative predictions of chemical behavior and distribution are made. Limited testing of model-predicted versus measured concentrations have been attempted. In recent years, quality and quantity of emission and monitoring data have improved dramatically. Such information was used in calibration and validation exercises with eight chemicals in the Louisiana chemical corridor, which receives inputs from urban, industrial, and agricultural sources. Geographically, the corridor was nested within the state of Louisiana, which was in turn nested within the continental United States. Parameter sensitivity studies, including transport coefficients, temperature, and degradation half-life revealed that the latter produces the largest range of variation in predicted concentrations. Published half-life data were used with benzene, vinyl chloride, 1,1,1-trichloethane, and atrazine in a calibration phase with 1995 monitoring data at steady state; this allowed selection of the appropriate emission database. A validation exercise was performed with toluene, styrene, trichloroethylene, and metribuzin. Predictions were compared to average measured concentrations. Atrazine and metribuzin reside primarily in the water; the others reside in the air. The predicted concentrations for benzene, metribuzin, and trichloroethylene were low by a factor of less than two. Vinylchloride, toluene, and 1,1,1-trichloroethane were low by factors between 3 and 10. Styrene and atrazine were low by factors of 45 and 65, respectively.

Agriculture↗
PubMed1994

The healing web: an expansion of consciousness.

The search for community manifest in society today reflects the apparent alienation, unconnectedness, and superficiality of modern life. A group of nurses in education and service created a community filled with caring and trust that designed the Healing Web, a transformative model for nursing. The web was established to create partnerships that will transform the health care paradigm of society. By establishing and maintaining a healing community within nursing and the larger universe, wholistic and integrative life will be restored.

Community Participation↗
PubMed1988

A comparison of markers of human fibroblast transformation induced by chemical carcinogen treatment or by transfection of an origin-defective SV40-containing plasmid.

We have investigated the sensitivity to oncogenic transformation by an origin-defective SV40-containing plasmid, '8-16' (ori-SV40), of skin fibroblasts from normal individuals (NF), and from patients with 2 hereditary diseases characterized by an increased cancer risk, Bloom's syndrome (BS) and Fanconi's anemia (FA). It was hypothesized that perhaps these cells had already undergone some stage, or stages, of the progression to neoplasia, and that as a consequence of these changes, one could observe differential expression of characteristics of the transformed phenotype in these cells compared to normal, or perhaps they would behave differently in vivo. The data showed that FA cells and NF possessed comparable sensitivities to transformation by ori-SV40 DNA transfection, as measured either by focus formation above a confluent monolayer, or anchorage-independent growth. The BS cells, on the other hand, were 5-10 times less sensitive to this method of transformation, and further, the transformed phenotype was unstable. The resistance of BS cells to transformation by the 8-16 plasmid may be a reflection of their inherent genetic instability which affects stable integration and expression of the transfected plasmid DNA, since no differences in initial uptake of transfected DNA were observed between the various cell strains. Immortality and tumorigenicity were not readily demonstrated in this ori-SV40 transformation model. The results are discussed in relationship to the characteristics of the transformed phenotype of chemically treated normal human fibroblasts. SV40, an agent known to transform human cells, can be cast in a positive control role with respect to the appropriateness of the assays, the frequency of appearance of various markers, immortality and tumorigenicity. The tumorigenicity results are further compared to results obtained during the establishment of a wide range of fresh human tumor biopsies as xenograft lines in athymic nude mice, with particular emphasis on the sarcoma data.

Animals↗
PubMed1992

Suppression of tumorigenicity and anchorage-independent growth of BK virus-transformed mouse cells by human chromosome 11.

Viral transformation models may be useful for detecting and mapping human tumor suppressor genes. BK virus (BKV), a human papovavirus, readily transforms rodent cells but is unable to transform human cells, suggesting that oncosuppressive functions expressed in human cells control BKV oncogenic activity. We have transferred human chromosome 11 to BKV-transformed mouse cells. All of the cell clones were suppressed in the tumorigenic phenotype and anchorage-independent growth, except one clone which was nontumorigenic but maintained the ability to grow in soft agar. Cytogenetic analysis and DNA hybridization with chromosome 11-specific probes showed that all the reverted hybrids had an intact human chromosome 11, except the clone growing in semisolid medium which had lost the short arm. The results suggest that a gene located on 11p controls anchorage independence, whereas a gene on 11q controls the tumorigenicity of BKV-transformed cells. BKV T-antigen was expressed in all the hybrid clones at the same level as in the parental cell line, indicating that the putative human tumor suppressor gene(s) do not inhibit expression of the viral oncogene and must operate by another mechanism in inducing reversion of the oncogenic phenotype. Since BKV-transformed mouse cells are highly susceptible to retrovirus infection, this model can be used for searching and cloning tumor suppressor gene(s) by retrovirus-mediated "insertional mutagenesis".

Animals↗
PubMedDate not supplied

Wound epithelialization deficits in the transforming growth factor-alpha knockout mouse.

In vitro, transforming growth factor-alpha is an important factor controlling epithelial cell proliferation and migration. However, the transforming growth factor-alpha knockout mouse has shown no wound epithelialization defect in tail amputation and full-thickness back wounds. To resolve this disparity, we combined a full-thickness head wound and a partial-thickness ear wound on the transforming growth factor-alpha knockout mouse for analysis of wound epithelialization with or without granulation tissue formation. Three-millimeter ear wounds were made on the transforming growth factor-alpha knockout and heterozygous control mice. Full-thickness head wounds were made using a 6-mm trephine on the crown of the skull. In the ear model, transforming growth factor-alpha knockout mice had significantly larger epithelial gaps versus control at post-operative day 3 and 5. Epithelial thickness at the wound edge of transforming growth factor-alpha deficient mice was also depressed at post-operative day 3 and post-operative day 5 compared to control mice. On post-operative day 8, most wounds of both groups were epithelialized. In contrast, no difference in epithelial gap or new granulation tissue was found in the head model. The data support the concept that transforming growth factor-alpha plays a significant early role in wound epithelialization in vivo but its deficit is compensated if accompanied by granulation tissue formation. The data further show the importance of appropriate wound models to address the role of vulnerary factors.

Animals↗
PubMed2004

Photodegradation of organic pollutants on the spruce needle wax surface under laboratory conditions.

The photochemistry of selected organic compounds, including common pollutants, on the paraffin (as a model matrix) and spruce wax surfaces was studied under laboratory conditions. Two model transformations were evaluated: (1) intramolecular rearrangements of valerophenone and 2-nitrobenzaldehyde, and (2) hydrogen abstraction between an excited benzophenone and the hydrocarbon paraffin/wax chains. The steric or polar influence of the solid matrix on conformational and translational motion, its optical properties, hydrogen abstraction probabilities, and consequences of the guest-molecule segregation are discussed in this work. Furthermore, the photochemical reactivity of some common anthropogenic pollutants, such as chlorinated biphenyls (4-chlorobiphenyl, 2,4-dichlorobiphenyl, and 4,4'-dichlorobiphenyl), 4-chlorophenol, and DDT, was evaluated. The surface of spruce wax is presented as probable reaction medium for photochemical transformations. Although the matrix presents certain restrictions for bimolecular reactions, common photodegradations should be generally feasible in nature. In addition, paraffin was found to be a suitable model matrix for the studies of possible photochemical transformations that can occur on natural plant surfaces.

Air Pollutants↗
PubMed2000

Acrylonitrile-induced morphological transformation in Syrian hamster embryo cells.

Acrylonitrile (ACN) is a monomer used in the synthesis of rubber, fibers and plastics. Previous studies demonstrated that ACN induces brain neoplasms (predominately astrocytomas) in rats following chronic treatment. While the mechanisms of ACN-induced glial cell carcinogenicity have not been completely elucidated, investigations by our group and others have suggested a role for the induction of oxidative stress and the resultant oxidative damage in this process. In vitro cell transformation models are useful for detecting and studying the mechanisms of chemical carcinogenesis. Cell transformation by chemical carcinogens in Syrian hamster embryo (SHE) cells exhibits a multistage process similar to that observed in vivo, for both non-genotoxic and genotoxic carcinogens. In the present study, the ability of ACN to induce morphological transformation and oxidative damage was examined in SHE cells. ACN induced an increase in morphological transformation at doses of 50, 62.5 and 75 microg/ml (maximum sub-toxic dose tested) following 7 days of continuous treatment. SHE cells exposed to ACN for 24 h failed to increase morphological transformation. Morphological transformation by ACN was inhibited by co-treatment with the antioxidants alpha-tocopherol and (-)-epigallocathechin-3 gallate (EGCG) for 7 days. Treatment of SHE cells with 75 microg/ml ACN produced a significant increase in 8-hydroxy-2'-deoxyguanosine that was also inhibited by co-treatment with alpha-tocopherol or EGCG. These results support the proposal that oxidative stress and the resulting oxidative damage is involved in ACN-induced carcinogenicity.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

SMART-PET: multimodality white matter imaging and display without loss of quantitative information.

PURPOSE: To improve analysis of cerebral white matter (WM) in fluoro-deoxy-glucose positron emission tomography (PET) images. MATERIALS AND METHODS: A multimodality analysis technique (segmented MRI and registered Talairach-transformed PET [SMART-PET]) was used for quantitative assessment of WM metabolism. Data processing included Talairach transformation of three-dimensional magnetic resonance imaging (MRI) and subsequent automated segmentation and coregistration to normalized PET images. Color model transformations were used for combined display: the hue saturation value color model was regarded as a three-dimensional data matrix, integrating quantitative voxel data of both modalities. The technique was applied in normal subjects and in patients suffering from different WM diseases. Regional analysis was performed to classify metabolic impairment on a five-point scale. RESULTS: Using SMART-PET, a considerable gain in image contrast for WM was achieved in all cases. In the normal subjects, WM metabolism was shown to be homogeneously unimpaired. Sum scores of regional analysis revealed metabolic WM changes in all patients. Extent of WM hypometabolism exceeded the extent of the lesions as delineated by MRI signal changes. CONCLUSION: The potential of the method for further elucidation of the role of WM diseases in brain dysfunction in patients is discussed.

Brain↗