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P Dole

Publications and source records attributed to P Dole.

14 recordsLinked to original sources
PubMed2006

Modelling of migration from multi-layers and functional barriers: estimation of parameters.

Functional barriers form parts of multi-layer packaging materials, which are deemed to protect the food from migration of a broad range of contaminants, e.g. those associated with reused packaging. Often, neither the presence nor the identity of the contaminants is known, so that safety assessment of the materials has to rely on predictive tools. Several complementary freeware described here allow one to model diffusion in multi-layer films. These tools require the input of parameters that are not easy to determine or predict. Previous work has focused on the prediction of diffusion coefficients at storage temperatures of packaging in contact with food. However, many other kinetic and thermodynamic parameters are needed to describe transport properties during the processing of a material at high temperature and during its shelf-life. All parameters needed for the calculations are discussed. In order to propose default values, the approach consists of (1) reviewing the available literature data, (2) running experiments on polypropylene, polyethylene and poly(ethylene vinyl alcohol) in typical conditions (separately diffusion during processing and migration) and (3) simulating numerical sets for typical situations. Several freeware are proposed to simulate migration from multi-layers and functional barriers using the default parameters.

Computer Simulation↗
PubMed2006

Strategies for self-management of HIV-related anxiety.

This study examines the frequency and effectiveness of commonly used strategies for self management of anxiety in an international sample of 502 participants from Norway (n=42, 8%), Taiwan (n=35, 7%), and the US (n=426, 85%). An activities checklist summarized into five categories of self-care behaviours including activities/thoughts, exercise, medications, complementary therapies, and substance use determined self-care behaviours. Ratings of frequency and effectiveness for each self-care activity were also included. Praying received the highest overall rating of effectiveness of any self-management strategies included in this study at 8.10 (scale 1 to 10), followed by meditation (7.37), exercising (7.32), using relaxation techniques (7.22), cooking (6.98), and walking (6.90). An analysis of effectiveness scores for each self-care strategy by country reflected a wide variation. The three most effective anxiety self-care strategies reported by participants from Norway included exercise (7.31), walking (6.96), and reading (6.44). Highest ratings of effectiveness by participants from Taiwan included talking with others with HIV (6.0), attending support groups (6.0), and exercising (6.0). US participants allocated highest ratings of effectiveness to complementary/alternative therapies, including praying (8.10), meditating (7.43), and using relaxation techniques (7.35). Regardless of the country, watching television and talking with family and friends were the two most frequently reported strategies. These strategies for self-management of HIV-related anxiety are important for clinicians to be aware of in the care of persons with HIV/AIDS.

Adult↗
PubMed2005

Functional barriers: properties and evaluation.

Functional barriers are multilayer structures deemed to prevent migration of some chemicals released by food-contact materials into food. In the area of plastics packaging, different migration behaviours of mono- and multilayer structures are assessed in terms of lag time and of their influence of the solubility of the migrants in food simulants. Whereas barriers to oxygen or to aromas must prevent the diffusion of these compounds under conditions of use, a functional barrier must also be efficient under processing conditions, to prevent diffusion of substances when the polymer layers are in contact at high (processing) temperatures. Diffusion in melted polymers at high temperatures is much slower for glassy polymers, than in polymers that are rubbery at ambient temperature. To evaluate the behaviour of functional barriers under conditions of use, a set of reference diffusion coefficients in the 40-60 degrees C range were determined for 14 polymers. Conditions for accelerated migration tests are proposed based on worst-case activation energy in the 40-60 degrees C range. For simulation of migration, numerical models are available. The rules derived from the models can be used both by industry (to optimize a material in terms of migration) or by risk assessors. Differences in migration behaviour between mono- and multilayer materials are discussed.

Alkanes↗
PubMed2002

Migration of additives from polymers into food simulants: numerical solution of a mathematical model taking into account food and polymer interactions.

The principle of a computing program describing precisely the migration of additives from a polymer into a food simulant is presented. As six parameters are used to fit the simulnnt sorption and additive extraction kinetics, the parameters have been determined by independent experiments. Owing to the complicated coupling between the liquid and additive diffusion processes, migration kinetics cannot be obtained by a mathematical resolution of kinetic equations, but they must be calculated by numerical analysis. The method is applied to a UV absorber in polypropylene migrating into glyceryl tripelargonate, a pure triglyceride, of which behaviour and average molecular weight are similar to official fatty food simulants. Properly designed experiments validate the model used to fit the migration kinetics. The possibility of erasing any parameters is also discussed.

Computer Simulation↗
PubMed2002

Integrated approach of migration prediction using numerical modelling associated to experimental determination of key parameters.

The principle of utilizing a computing program describing precisely the migration of additives from a polymer into a food simulant is presented. The model has been validated with a UV absorber in polypropylene migrating into glyceryl tripelargonate, a pure triglyceride whose behaviour and average molecular weight are similar to Myglyol (a synthetic mixture of C8-C12 triglycerides). Six parameters were used to fit the simulant sorption and additive extraction kinetics, and these were determined by independent experiments. The possibility of eliminating any of the parameters is also discussed. This work provides the first consistent set of experimental data that can be used to overestimate the diffusion coefficients of additives both in virgin (without contact with solvent) and in swollen (fat contact) polymer. The influence of mobility increase brought out by temperature or swelling are compared. The effects were more important for high molecular weight compounds.

Diffusion↗
PubMed2001

Synthesis, characterisation and water sorption properties of pectin-dehydrogenation polymer (lignin model compound) complex.

Coniferyl alcohol was polymerised in the presence of pectin and a pectin-DHP complex was isolated. Characterisation of the complex has demonstrated that DHP (20% wt) was covalently linked by ester bonds to the pectin. The water sorption behaviour of the pectin-DHP complex was determined at several relative vapour pressures and compared with those obtained on pectin, DHP and a blend of both polymers in the same proportion as in the complex. The complex exhibited a lower hydrophilicity resulting from three associated phenomena: grafting, pectin-DHP interactions and the formation of a chemical network.

Chromatography, Gel↗
PubMed1999

Prediction of worst case migration: presentation of a rigorous methodology.

An improvement of the Piringer model, allowing the prediction of a worst case migration from packaging to food is presented here. The authors are proposing other constants for the calculation of the upperbound value of the diffusion coefficient, using experimental data determined by a film to film method. Considering the plasticizing effects of food simulants, a model involving the variation of the diffusion coefficient versus space and time must be used. Future fields of investigation are discussed: the relationship between diffusion coefficients and the volume of the migrant (instead of molar mass), and the variation of diffusion coefficient activation energy with temperature.

Computer Simulation↗
PubMed1996

Significance of mild cytologic atypia in women infected with human immunodeficiency virus.

OBJECTIVE: To determine the prevalence of cervical intraepithelial neoplasia (CIN) in women who are infected with human immunodeficiency virus (HIV) and who have mild cytologic atypia. METHODS: As part of an ongoing, prospective study of cervical disease in HIV-infected women, Papanicolaou smears were analyzed cross-sectionally for the diagnosis of mild cytologic atypia. RESULTS: Mild cytologic atypia was diagnosed in 112 (25%) of the 453 HIV-infected women enrolled in this study, compared with 36 (9%) of the 401 HIV-uninfected women (odds ratio [OR] 3.3, 95% confidence interval [CI] 2.2-5.1; P < .001). Mild cytologic atypia was diagnosed more frequently in HIV-infected women with lower CD4+ T-lymphocyte counts (chi2 for trend, P = .015) and in those with a history of an abnormal Papanicolaou smear or treatment for cervical disease (OR 3.0, 95% CI 1.2-7.6; P = .008). Coexistent CIN was detected by colposcopically directed biopsy in 42 (38%) of the 112 HIV-infected women with mild cytologic atypia, compared with five (14%) of the 36 HIV-uninfected women (OR 3.7, 95% CI 1.3-11.9; P = .008). Severe inflammation with associated epithelial reparative atypia was diagnosed in 90 (20%) of the HIV-infected women and in 87 (22%) of the HIV-uninfected women. Coexistent CIN was detected in 12% of the HIV-infected women with severe inflammation and associated epithelial reparative atypia, compared with 2% of the HIV-uninfected women with this cytologic diagnosis (OR 5.9, 95% CI 1.2-23; P = .01). CONCLUSION: Mild cytologic atypia, a frequent diagnosis on Papanicolaou smears from HIV-infected women, is associated with CIN. We recommend that all HIV-infected women with mild cytologic atypia be referred for colposcopy.

Adult↗
PubMed1996

Characteristics of menstruation in women infected with human immunodeficiency virus.

OBJECTIVE: To determine the characteristics of menstruation in women infected with human immunodeficiency virus (HIV) and the impact of immunosuppression on menstruation in HIV-infected women. METHODS: In this cross-sectional study, 197 HIV-infected and 189 HIV-uninfected women were interviewed about menstruation and abnormal vaginal bleeding during the previous 12 months. Information was also obtained about CD4+ T-lymphocyte levels of HIV-infected women and other factors, including drug use and weight loss, that might affect menstruation. RESULTS: The number and duration of menses in HIV-infected women were not significantly different from those of uninfected women. During a 12-month period, 154 (78%) of 197 HIV-infected women and 150 (80%) of 188 uninfected women had 10-14 menses (P = .74). The proportions of women in the two groups with intermenstrual bleeding, postcoital bleeding, or no bleeding were also similar. In HIV-infected women, menstruation and the prevalence of abnormal vaginal bleeding were not significantly different by CD4+ T-lymphocyte level. By multiple logistic regression analysis, neither HIV infection nor CD4+ T-lymphocyte level less than 200 cells/microL was associated with intermenstrual bleeding, postcoital bleeding, or no bleeding. CONCLUSION: The results of this study suggest that neither HIV infection nor immunosuppression has a clinically relevant effect on menstruation or other vaginal bleeding. Most HIV-infected women menstruate about every 25-35 days, suggesting monthly ovulation and an intact hypothalamic-pituitary-ovarian axis.

Adult↗
PubMed1996

Prevalence of anal human papillomavirus infection and anal cytologic abnormalities in HIV-seropositive women.

OBJECTIVE: To determine the prevalence of anal human papillomavirus (HPV) infections and anal cytologic abnormalities in HIV-seropositive and HIV-seronegative women. DESIGN: This cross-sectional study of a cohort of women with known HIV serostatus involved a standardized interview and a gynecologic examination, including a cytologic evaluation of the cervix and anus. Anal swabs were tested for HPV DNA using the Hybrid Capture assay. SETTING: Two HIV/AIDS clinics, a sexually transmitted disease clinic, a methadone clinic and women enrolled in a study of HIV heterosexual transmission in the greater New York City metropolitan area. PATIENTS: One hundred and two HIV-seropositive and 96 HIV-seronegative women were selected from an ongoing study of the gynecologic manifestations of HIV infection. MAIN OUTCOME MEASURES: Detection of anal HPV DNA and anal cytologic abnormalities. RESULTS: Anal cytologic abnormalities were detected in 27 (26%) of the 102 HIV-seropositive women and in six (7%) of 96 HIV-seronegative women. Five (5%) of the anal smears from the HIV-seropositive women and one (1%) from the HIV-seronegative women had low-grade anal intra-epithelial neoplasia. The remainder of the anal cytologic abnormalities were classified as mild squamous cytologic atypia. HPV DNA was detected in 30 (29%) of 102 HIV-seropositive and two (2%) of 96 HIV-seronegative women. Of the 33 patients with anal cytologic abnormalities, 19 (58%) had anal HPV DNA detected as compared to 13 (8%) of 160 women without cytologic abnormalities (P < 0.001). In a multivariate logistic regression analysis, HIV-seropositivity was found to be an independent risk factor for both anal HPV infection and anal cytologic abnormalities and the strength of the association was greater in women with lower CD4+ T-lymphocyte counts. CONCLUSION: The prevalence of both anal cytologic abnormalities and anal HPV infection are significantly increased in HIV-seropositive women.

Adult↗
PubMed1996

Low prevalence of human papillomavirus infection of the cervix in renal transplant recipients.

BACKGROUND: An increased risk of anogenital tract malignancies has been noted among renal transplant recipients. A high prevalence of human papillomavirus (HPV) infection of the cervix in the female renal-transplant population has been assumed based on increasing evidence suggesting that HPV infection is the major risk factor for cervical intraepithelial neoplasia (CIN) and cervical cancer. It has been assumed that immunosuppression leads to either a reactivation of latent HPV or a reduction in the host's ability to contain a primary HPV infection, thereby increasing the risk of CIN and cervical cancer. The objective of this study was to evaluate the prevalence of human papillomavirus (HPV) infection in a population of iatrogenically immunosuppressed renal transplant recipients. METHODS: Twenty-one women were recruited from the renal transplant clinic at Presbyterian Hospital and underwent a gynaecological examination which included colposcopy, a Papanicolaou smear, and a cervicovaginal lavage. Lavage samples were analysed for HPV DNA using L1 consensus primers and the polymerase chain reaction (PCR). RESULTS: No cases of cervical intraepithelial neoplasia (CIN) were detected in this cohort of 21 immuno-suppressed renal transplant recipients. HPV DNA was detected in only a single patient. CONCLUSIONS: Our data suggests that HPV infection is not highly prevalent among older, cytologically normal renal transplant recipients, particularly those who are currently monogamous or not presently sexually active. This study suggests that recent sexual behaviours are more important than past behaviours as a determinant of HPV status in transplant recipients, and also suggests that education concerning the avoidance of high-risk sexual behaviour is an important part of the care of the female renal transplant recipient. Our data is consistent with previous work suggesting that the incidence of CIN is declining in transplant recipients, and it also suggests that the prevalence of HPV infection may be declining as well.

Adult↗
PubMed1992

Inactivation of maize phosphoenolpyruvate carboxylase by urea.

Phosphoenolpyruvate carboxylase purified from leaves of maize (Zea mays, L.) is sensitive to the presence of urea. Exposure to 2.5 m urea for 30 min completely inactivates the enzyme, whereas for a concentration of 1.5 m urea, about 1 h is required. Malate appears to have no effect on inactivation by urea of phosphoenolpyruvate carboxylase. However, the presence of 20 mm phosphoenolpyruvate or 20 mm glucose-6-phosphate prevents significant inactivation by 1.5 m urea for at least 1 h. The inactivation by urea is reversible by dilution. The inhibition by urea and the protective effects of phosphoenolpyruvate and glucose-6-phosphate are associated with changes in aggregation state.

Journal Article↗
PubMed1984

Chlamydia trachomatis: important relationships to race, contraception, lower genital tract infection, and Papanicolaou smear.

Chlamydia trachomatis is a common cause of sexually transmitted disease in adolescent girls. Of 366 adolescent patients screened, 15.3% were found to have chlamydial endocervical infections, with an infection rate of 23.3% in blacks, 14.3% in Hispanics, and 10.3% in whites (P = 0.01, excess for blacks). Of Chlamydia-positive patients, 63.6% had a diagnosis of lower genital tract infection, compared with 35.4% of Chlamydia-negative patients (P = 0.004). Oral contraceptive users had a higher prevalence of infection (23.8%) compared with those using a barrier method (16.2%) or with nonusers (9.3%) (P = 0.004). Inflammatory changes on Papanicolaou smears were associated with chlamydial infection (P = 0.0001). Other variables identified as risk factors for chlamydial infection included both a younger age at first intercourse (P = 0.02) and more years of sexual activity (P = 0.02). Chronologic, menarchal, and gynecologic age, biologic age of the cervix, the number of sexual partners in the last month and during a lifetime, and parity were not found to be associated with recovery of Chlamydia.

Chlamydia Infections↗