Biomedical subjects

P Jensen

Publications and source records attributed to P Jensen.

At least 55 records · Page 3Linked to original sources

PubMed1999

Determination of the Effective Ground State Potential Energy Function of Ozone from High-Resolution Infrared Spectra.

The effective ground state potential energy function of the ozone molecule near the C(2v) equilibrium configuration was obtained in a least-squares fit to the largest sample of experimental, high-resolution vibration-rotation data used for this purpose so far. The fitting is based on variational calculations carried out with the extended Morse Oscillator Rigid Bender Internal Dynamics model. The potential function is expanded in Morse-type functions of the stretching variables and in cosine of the bending angle. The present calculation produces results in significantly better agreement with experiment than previous determinations of the potential energy surface, and the energies predicted with the new surface are sufficiently accurate to be useful for the assignment of new high-resolution spectra. The rms (root-mean-square) deviation of the fit of rovibrational data up to J = 5 is 0.02 cm(-1). For the set of all 60 band centers of the (16)O(3) molecule included in the Atlas of Ozone Line Parameters, the rms deviation is 0.025 cm(-1), and for all band centers determined so far from high-resolution spectra, including those recently observed and assigned in Reims corresponding to highly excited stretching and bending vibrations (v(1) + v(2) + v(3) = 6), the rms deviation is 0.1 cm(-1). The "dark states" that produce resonance perturbations in the observed bands are described with experimental accuracy up to the (v(1)v(2)v(3)) = (080) state. Extrapolation tests demonstrate the predictive power of the potential function obtained: rotational extrapolation up to J = 10 for the 11 lowest vibrational states results in an rms deviation of 0.06cm(-1). Also, vibrational energies measured by low-resolution Raman spectroscopy (which were not included in the input data for the fit) are calculated within the experimental accuracy (rms = 1.6 cm(-1)) of the experimental values up to the dissociation limit. The statistical analysis suggests that the accuracy of the equilibrium geometry and force constants of the molecule is considerably improved relative to previous determinations. The long-range behavior of the fitted potential at the dissociation limit O(3) --> O(2) + O shows very good agreement with experimental data. The new potential energy surface was used to predict the band centers of the isotopomers (17)O(3) and (18)O(3). Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

The H(2)O(++) Ground State Potential Energy Surface.

At the correlation-consistent polarized-valence quadruple-zeta complete active space self-consistent field second-order configuration interaction level of ab initio theory (cc-pVQZ CASSCF-SOCI), we calculated 129 points on the ground electronic state potential energy surface of the water dication H(2)O(++); this calculation includes the energy of;X(3)Sigma(-) OH(+) at equilibrium and the energy of the triplet oxygen atom. We determined the parameters in an analytical function that represents this surface out to the (OH(+) + H(+)) and (O + 2H(+)) dissociation limits, for bending angles from 70 to 180 degrees. There is a metastable minimum in this surface, at an energy of 43 600 cm(-1) above the H(+) + OH(+) dissociation energy, and the geometry at this minimum is linear (D(infinityh)), with an OH bond length of 1.195 Å. On the path to dissociation to H(+) + OH(+), there is a saddle point at an energy of 530 cm(-1) above the minimum, and the geometry at the saddle point is linear (C(infinity Kv)) with OH bond lengths of 1.121 and 1.489 Å. Using the stabilization method, we calculated the lowest resonance on this surface. Relative to the metastable local minimum on the potential energy surface, the position of the lowest resonance for H(2)O(++), D(2)O(++), and T(2)O(++) is 1977(85), 1473(25), and 1249(10) cm(-1), respectively, where the width of each resonance (in cm(-1)) is given in parentheses. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Skin cancer in kidney and heart transplant recipients and different long-term immunosuppressive therapy regimens.

BACKGROUND: Nonmelanoma skin cancer occurs frequently in organ transplant recipients, but the relative importance of different immunosuppressive therapy regimens is unclear. OBJECTIVE: We studied the risk of skin cancer in the complete, single-center Norwegian cohort of kidney and heart transplant recipients (n = 2561). METHODS: We determined cancer risk estimation by means of standardized incidence ratios and multivariate Cox regression. RESULTS: Transplant recipients had an increased risk of cutaneous squamous cell carcinoma (SCC) (65-fold), malignant melanoma (3-fold), and Kaposi's sarcoma (84-fold), and of lip SCC (20-fold), compared with the general population. After adjustment for age, kidney transplant recipients receiving cyclosporine, azathioprine, and prednisolone had a significantly (2.8 times) higher risk of cutaneous SCC relative to those receiving azathioprine and prednisolone. After adjustment for age and type of immunosuppressive regimen, heart transplant recipients had a significantly (2.9 times) higher risk than kidney transplant recipients. CONCLUSION: The risk of cutaneous SCC, malignant melanoma, Kaposi's sarcoma, and lip SCC is increased in kidney and heart transplant recipients. The risk of posttransplant cutaneous SCC is related to the degree of immunosuppression caused by long-term immunosuppressive therapy.

Adolescent↗

PubMed1999

Informant-based determinants of symptom attenuation in structured child psychiatric interviews.

Informant-related determinants of item attenuation, that is, the drop-off in symptom endorsement rates at retest, were examined in an enriched community subsample of 245 parent-child pairs drawn from the National Institute of Mental Health Methods for Epidemiology of Child and Adolescent Mental Disorders Study. Youngsters and their parents were interviewed with the Diagnostic Interview Schedule for Children (Version 2.3; DISC-2.3) on two occasions with a mean test-retest interval of 12 days. Item attenuation rates were high for both informants, with adults failing to confirm 42% and children 58% of baseline responses at retest. Stepwise regressions revealed that item attenuation at DISC-P retest was higher for adult informants who were younger, and who reported on older and less impaired children. On the DISC-C, attenuation was higher for children who were less impaired, rated as doing worse in school, and who had a longer test-retest interval. These results are broadly consistent with past studies examining the determinants of attenuation and test-retest reliability and have implications for the design and use of structured diagnostic instruments.

Adolescent↗

PubMed1999

Relation of age of onset to the type and severity of child and adolescent conduct problems.

In a cross-sectional household sample of 9-through 17-year-old youths from 4 U.S. communities, youths with earlier ages of onset of conduct problems engaged in more conduct problems than youths with later ages of onset when current age and gender were controlled. Specifically, youths with earlier ages of onset were more likely to engage in several types of physical aggression, frequent lying, theft, and vandalism and were less likely to engage in only truancy. There also was an inverse relation between age of onset and level of functional impairment, mental health service use, and meeting diagnostic criteria for conduct disorder, attention-deficit hyperactivity disorder, and oppositional defiant disorder. Within the limits of cross-sectional data, these results support the hypothesis that key aspects of the heterogeneity of conduct problems among youths are related to the age of onset of conduct problems.

Adolescent↗

PubMed1999

Differences in sialyl-Tn antigen expression between keratoacanthomas and cutaneous squamous cell carcinomas.

Keratoacanthoma and squamous cell carcinoma are common skin tumors, especially in immunosuppressed transplant recipients, but the distinction between these two types of epidermal neoplasia may be difficult. Sialyl-Tn (Sia-GalNAc-O-Ser/Thr) is a cell surface carbohydrate associated with hyperplasia in squamous epithelium, and correlated with poor prognosis in several human adenocarcinomas. Twenty-seven keratoacanthomas and 29 cutaneous squamous cell carcinomas were examined for the expression of sialyl-Tn and of the Ki67 epitope, the latter a marker for cell proliferation. By immunohistochemistry, basaloid tumor cells at the periphery of tumor nests showed some degree of sialyl-Tn expression in 16 keratoacanthomas (59%), while only three squamous cell carcinomas (10%) showed sialyl-Tn-positive basaloid tumor cells (p<0.001). Keratinized, differentiated tumor cells were more often sialyl-Tn-positive in keratoacanthomas (89%) than in squamous cell carcinomas (31%) (p<0.001). A striking sialyl-Tn-positivity in the basal cell layer was found in a border zone directly adjacent to most tumors of both types (88 and 88%). By immunohistochemical examination of parallel sections and by double immunofluorescence, sialyl-Tn antigen expression was primarily seen in cells that did not express Ki67, although some overlap was present. Keratoacanthomas from transplant recipients did not differ in sialyl-Tn expression compared to those from non-immunosuppressed patients. The results indicate that sialyl-Tn expression is not directly related to cell proliferation, but rather to cellular features of post-mitotic cells, and that sialyl-Tn is not associated with a malignant phenotype. Sialyl-Tn may be linked to tumor regression, as seen in keratoacanthomas.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed1999

Avidity of anti-P aeruginosa antibodies during chronic infection in patients with cystic fibrosis.

BACKGROUND: In order to study the impact on the lung function of patients with cystic fibrosis of the avidity of antipseudomonal antibodies, the avidity of antibodies against the chromosomal beta-lactamase of Pseudomonas aeruginosa (a beta ab) and against the 60-65 kDa heat shock protein of P aeruginosa (anti-GroEL) were measured in serum samples collected longitudinally during chronic infection with P aeruginosa from a group of patients with poor and good lung function. METHODS: The thiocyanate elution method in which the molarity of potassium thiocyanate required to elute 50% bound antibody under conditions of antigen excess in ELISA was used to measure the relative avidity. RESULTS: All patients developed increasing levels of a beta ab and anti-GroEL antibodies during the follow up period but no maturation of the avidity of these antibodies was observed. In patients with good lung function the avidity of a beta ab was higher than in patients with poor lung function (p = 0.018). No significant difference in the avidity of the anti-GroEL antibodies was observed between the two groups of patients. CONCLUSION: In patients with cystic fibrosis a high avidity of a beta ab could contribute to a more efficient inhibition of the beta-lactamase by these antibodies, resulting in the better lung function seen in this group. The immunopathological implication of the failure in avidity maturation of antibodies in chronic infection is discussed.

Antibodies, Bacterial↗

PubMed1999

Breast-feeding and alcoholism: the Trotter hypothesis.

OBJECTIVE: The authors' goal was to determine whether early termination of breast-feeding contributes to later alcohol dependence, as proposed more than 200 years ago by the British physician Thomas Trotter. METHOD: In 1959-1961, a multiple-specialty group of physicians studied 9, 182 consecutive deliveries in a Danish hospital, obtaining data about prepartum and postpartum variables. The present study concentrates on perinatal variables obtained from 200 of the original babies who participated in a 30-year high-risk follow-up study of the antecedents of alcoholism. RESULTS: Of the 27 men who were diagnosed as alcohol dependent at age 30, 13 (48%) came from the group weaned from the breast before the age of 3 weeks; only 33 (19%) of the 173 non-alcohol-dependent subjects came from the early weaning group. When challenged by other perinatal variables in a multiple regression analysis, early weaning significantly contributed to the prediction of the severity of alcoholism at age 30. CONCLUSIONS: The data support the hypothesis that early weaning may be associated with a greater risk of alcohol dependence later in life.

Adult↗

PubMed1999

Effect of Bacillus Calmette-Guerin vaccination on new-onset type 1 diabetes. A randomized clinical study.

OBJECTIVE: We undertook this study to test whether Bacillus Calmette-Guerin (BCG) vaccine preserves beta-cell function and increases the remission rate in children with new-onset type 1 diabetes. RESEARCH DESIGN AND METHODS: This was a randomized double-blind placebo-controlled trial offered to children referred to the Barbara Davis Center for Childhood Diabetes or the Baystate Medical Center with a diagnosis of new-onset type 1 diabetes. There were 94 children aged 5-18 years who received either BCG or saline intradermally within 4 months of onset of symptoms and who were then evaluated at 3-month intervals for 2 years. The primary end point was remission, defined as insulin independence for 4 weeks. Secondary end points were C-peptide levels (fasting and in response to a mixed meal challenge), insulin dose, and HbA1c. RESULTS: Of the patients, 47 were randomized to each arm; 7 in the placebo group and 9 in the BCG group did not complete 1 year of the study and are not included in the analysis. One patient from each group achieved remission. Fasting and stimulated C-peptide levels did not differ by treatment arm but declined in both groups and were lower initially and during the entire 2-year period in younger children. Insulin requirements and HbA1c levels did not differ in the two groups. CONCLUSIONS: Vaccination with BCG at the time of onset of type 1 diabetes does not increase the remission rate or preserve beta-cell function.

Adolescent↗

PubMed1999