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PubMed1999

Practical considerations in using calculated healthy-tissue complication probabilities for treatment-plan optimization.

PURPOSE: Healthy and neoplastic tissues are generally exposed nonuniformly to ionizing radiation. It is thus useful to develop algorithms that predict the probability of tumor control or normal tissue complication probability (NTCP) for any given spatial pattern of dose delivery. The questions addressed here concern: (a) the sensitivity of the NTCP predictions to the actual model used for extrapolation from uniform irradiation (where some clinical data exist) to nonuniform exposures, (b) its dependence on tissue type, and (c) consequences for treatment-plan optimization. METHODS AND MATERIALS: Two (of several possible) NTCP formulations are used here: the Lyman model and a binomial equation. The effective volume-reduction scheme of Kutcher and Burman is used to obtain the NTCP for an arbitrary distribution of dose. NTCP was calculated for seven organs by postulating a dose distribution of maximum nonuniformity. RESULTS: Both models fit available NTCP data well, but have very different extrapolations for exposures of small tissue volumes and very low values of NTCP (e.g., < 5%) where no data exist. Organs with pronounced volume effects (lung, kidneys) show substantial NTCP differences between the two models. Even in organs where the volume effect is small (e.g., spinal cord, brain), differences in NTCP due to the model selected may still have serious clinical consequences, as an actual example (for the spinal cord) indicates. CONCLUSIONS: NTCP calculations based on extrapolations to volume fractions and/or NTCP levels for which reliable data do not exist depend on the model used to fit the data and the degree of dose nonuniformity. If NTCP is to be used in treatment-plan optimization, the prudent approach is to design plans that reproduce the conditions under which available dose-volume data were taken (e. g., uniform dose distributions).

Algorithms↗
PubMed2003

Differential inhibition of fracture healing by non-selective and cyclooxygenase-2 selective non-steroidal anti-inflammatory drugs.

Non-steroidal anti-inflammatory drugs (NSAIDs) specifically inhibit cyclooxygenase (COX) activity and are widely used as anti-arthritics, post-surgical analgesics, and for the relief of acute musculoskeletal pain. Recent studies suggest that non-specific NSAIDs, which inhibit both COX-1 and COX-2 isoforms, delay bone healing. The objectives of this study were 2-fold; first, to measure the relative changes in the normal expression of COX-1 and COX-2 mRNAs over a 42 day period of fracture healing and second, to compare the effects of a commonly used non-specific NSAID, ketorolac, with a COX-2 specific NSAID, Parecoxib (a pro-drug of valdecoxib), on this process. Simple, closed, transverse fractures were generated in femora of male Sprague-Dawley rats weighing approximately 450 g each. Total RNA was prepared from the calluses obtained prior to fracture and at 1, 3, 5, 7, 10, 14, 21, 35 and 42 days post-fracture and levels of COX-1 and COX-2 mRNA were measured using real time PCR. While the relative levels of COX-1 mRNA remained constant over a 21-day period, COX-2 mRNA levels showed peak expression during the first 14 days of healing and returned to basal levels by day 21. Mechanical properties of the calluses were then assessed at 21 and 35 days post-fracture in untreated animals and animals treated with either ketorolac or high or low dose parecoxib. At both 21 and 35 days after fracture, calluses in the group treated with the ketorolac showed a significant reduction in mechanical strength and stiffness when compared with controls (p<0.05). At the 21-day time point, calluses of the parecoxib treated animals showed a lower mean mechanical strength than controls, but the inhibition was not statistically significant. Based on physical analysis of the bones, 3 of 12 (25%) of the ketorolac-treated and 1 of 12 (8%) of the high dose parecoxib-treated animals showed failure to unite their fractures by 21 days, while all fractures in both groups showed union by 35 days. Histological analysis at 21 days showed that the calluses in the ketorolac-treated group contained substantial amounts of residual cartilage while neither the control nor the parecoxib-treated animals showed comparable amounts of cartilage at this stage. These results demonstrate that ketorolac and parecoxib delay fracture healing in this model, but in this study daily administration of ketorolac, a non-selective COX inhibitor had a greater affect on this process. They further demonstrate that a COX-2 selective NSAID, such as parecoxib (valdecoxib), has only a small effect on delaying fracture healing even at doses that are known to fully inhibit prostaglandin production.

Animals↗
PubMed2000

Measurement of quality of life in alcohol-dependent subjects by a cancer symptoms checklist.

There are few studies of Quality of Life measures (QoL) in alcohol-misusing patients. The present study addresses this deficiency. The sample consisted of 60 (39 men, 21 women) alcohol dependent subjects defined by DSM-IV criteria (American Psychiatric Association, 1994). At baseline (4-5 days after admission and detoxification) sociodemographic data were collected, and three questionnaires were administered: the Rotterdam Symptoms Checklist (RSCL), the Severity of Alcohol Dependence Questionnaire (SADQ), and Alcohol Problems Questionnaire (APQ). QoL scores for dependent alcoholics both for physical and psychological measures were significantly worse (higher) than those reported for a variety of cancer patients. Psychological symptom scores were higher than physical symptoms at baseline. Correlations of RSCL scores to both SADQ and APQ were greater for RSCL physical compared to psychological symptom scores. The subjects were followed up at 12 weeks when the RSCL was re-administered and relapse status ascertained. Fifty-eight (97%) subjects were successfully contacted at 12 weeks of whom 36 (62%) had relapsed. After a repeated measures ANOVA psychological and physical symptom subscores were statistically significantly improved as a result of not relapsing to heavy drinking. There was no significant change in scores in the relapse group when baseline and week 12 scores were compared. The RSCL measure is a useful QoL assessment tool in alcohol-dependent subjects.

Adult↗
PubMed1996

Ultrasound versus physical examination in staging carcinoma of the mobile tongue.

Surgical therapy for early lesions of the tongue should have the potential to be both oncologically sound and easy to rehabilitate. Obviously, the amount of tongue left behind after surgery is proportional to the post-operative function. Hence accurate mapping of the diseased tongue is of paramount importance in order to limit or extend the resection margins. We have evaluated the use of ultrasound in carcinoma of the tongue, and also compared its relative accuracy with physical examination for determining the extent of growth, keeping the histopathological size as a gold standard. We found that ultrasound is more accurate in detecting T2 and T3 tumours than T1 lesions. Intraoral sonographic mapping may be the answer for such small lesions. In addition, ultrasonography is beneficial in showing spread to contiguous areas of the tongue. However, post-radiation fibrosis and frank residual disease were not differentiated accurately by ultrasound. Thus ultrasonography can be an effective investigative tool and together with physical examination it can increase diagnostic accuracy leading to precise surgery for carcinoma of the tongue.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

QSAR comparative study of Wiener descriptors for weighted molecular graphs.

Quantitative structure-property relationship (QSPR) and quantitative structure-activity relationship (QSAR) studies use statistical models to compute physical, chemical, or biological properties of a chemical substance from its molecular structure, encoded in a numerical form with the aid of various descriptors. Structural indices derived from molecular graph matrices represent an important group of descriptors used in QSPR and QSAR models; recently, their utilization was extended to molecular similarity and diversity, in database mining and virtual screening of combinatorial libraries. Initially defined from the distance matrix, the Wiener index W was the source of novel graph descriptors derived from recently proposed molecular matrices and of the Wiener graph operator. In this work we present a comparative study of several Wiener-type descriptors computed for vertex- and edge-weighted molecular graphs, corresponding to organic compounds with heteroatoms and multiple bonds. The acute toxicities toward Tetrahymena pyriformis of 47 nitrobenzenes are modeled with multilinear regression equations, using as structural descriptors the hydrophobicity (corrected for ionization) and various Wiener-type indices, with better results than a comparative molecular field analysis model.

Journal Article↗
PubMedDate not supplied

Modeling of Gibbs energy of formation of organic compounds by linear and nonlinear methods.

Two quantitative models for the prediction of the Gibbs energy of formation (DeltaGf degrees ) of 177 organic compounds were developed. These molecules contain elements such as H, C, N, O, F, S, Cl, and Br, with the molecular weight in the range of 16.04-202.25. The molecules were represented by six selected 2D-structure descriptors. At first, the complex relationship between DeltaGf degrees and the six selected input descriptors was depicted by a two-dimensional Kohonen's self-organizing neural network (KohNN) map; on the basis of the KohNN map, the whole data set was split into a training set consisting of 130 compounds and a test set (or a validation set and a test set) including 47 compounds. Then, DeltaGf degrees was predicted using a multilinear regression (MLR) analysis and a back-propagation (BPG) neural network. For 177 organic compounds, root-mean-square deviations of 17.8 and 15.4 kcal mol-1 were achieved by MLR and the BPG neural network, respectively.

Algorithms↗
PubMed2005

Quantitative structure--property relationships for enhancing predictions of synthetic organic chemical removal from drinking water by granular activated carbon.

Granular activated carbon is a frequently explored technology for removing synthetic organic contaminants from drinking water sources. The success of this technology relies on a number of factors based not only on the adsorptive properties of the contaminant but also on properties of the water itself, notably the presence of substances in the water which compete for adsorption sites. Because it is impractical to perform field-scale evaluations for all possible contaminants, the pore surface diffusion model (PSDM) has been developed and used to predict activated carbon column performance using single-solute isotherm data as inputs. Many assumptions are built into this model to account for kinetics of adsorption and competition for adsorption sites. This work further evaluates and expands this model, through the use of quantitative structure-property relationships (QSPRs) to predict the effect of natural organic matter fouling on activated carbon adsorption of specific contaminants. The QSPRs developed are based on a combination of calculated topographical indices and quantum chemical parameters. The QSPRs were evaluated in terms of their statistical predictive ability,the physical significance of the descriptors, and by comparison with field data. The QSPR-enhanced PSDM was judged to give results better than what could previously be obtained.

Adsorption↗
PubMed2006

Intermolecular vibrational coherence in bacteriochlorophyll a with clustered polar solvent molecules.

We show that resonant impulsive excitation of the Qy absorption band of bacteriochlorophyll a (BChl) launches a rapidly damped (gamma < 200 fs) ground-state coherent wave-packet motion that arises from intermolecular modes with clustered solvent molecules. Femtosecond pump-probe, dynamic-absorption signals were obtained at room temperature with BChl solutions in pyridine, acetone, and 1-propanol. The vibrational coherence observed in the 0-800-fs regime is modeled in the time domain by two (or three, in the case of 1-propanol) modulation components with asymmetric, inhomogeneously broadened line shapes and frequencies in the 100-200-cm(-1) range. The mean frequency of the vibrational coherence exhibits at least a quadratic dependence on the dipole moment of the solvent molecules and a y-intercept in the 100-cm(-1) regime. This trend is modeled by an expression for the natural frequency of a "6-12" potential composed of attractive terms from van der Waals forces and a repulsive term from the exchange (Pauli exclusion) force. The model suggests that comparable contributions to the potential are provided by the dipole-dipole and London dispersion interactions. These results support the hypothesis that the low-frequency vibrational modes in the 100-cm(-1) regime that are coupled to the light-driven charge-separation reactions in the reaction center from purple bacteria are derived from intermolecular vibrational modes between the chromophores and the surrounding protein medium.

1-Propanol↗
PubMed1990

Characterization of a hot-melt fluid bed coating process for fine granules.

The equipment modifications and process changes necessary to perform hot-melt particle coating in a fluid bed granulator are reviewed. A specific case is presented in which partially hydrogenated cottonseed oil is coated onto fine granules (mean particle size, 77 microns; range, 10-150 microns; one standard deviation is 10 microns) composed of a hydrophobic drug and sucrose. The major variables were product bed temperature, temperature of the wax, spray rate, and atomization air pressure. The product bed temperature was selected to give the optimum congealing rate, and the latter three variables were varied in a statistically designed experiment. The physical properties of wax-coated granules fabricated using combinations of process variables were examined. Response surface analysis was used to determine the optimum process settings in terms of dissolution, particle size, and density of the coated product. This system proved quite adequate for the production of uniformly coated granules, with the best product being obtained at the optimized conditions using 120 degrees C atomization air and molten coating temperature, 30 g/min as the spray rate, and an atomization air pressure of 5 bar.

Capsules↗
PubMed1998

Trait hostility and ambulatory cardiovascular activity: responses to social interaction.

This study examined trait hostility and social interaction in relation to ambulatory cardiovascular activity in 40 male and 39 female undergraduates. Participants wore an ambulatory blood pressure monitor and completed diary entries while engaged in everyday activities. Diary reports indicating that participants had been talking were used to identify cardiovascular readings taken during social interaction. Interaction effects for overall diastolic blood pressure and heart rate levels indicated that hostility was positively associated with these variables in men only. In addition, hostility was associated with higher systolic blood pressure during social interaction, an effect primarily due to data for men. Because physical activity was controlled statistically, it is likely that these effects were mediated by psychological processes. These findings are consistent with the hypothesis that cardiovascular reactivity to social interaction mediates the relationship between hostility and coronary disease, and they may have implications for understanding sex differences in coronary risk.

Affect↗
PubMed1998

Psychosocial adaptation of patients and families following bone marrow transplantation: a prospective, longitudinal study.

Using a prospective, repeated measures design, this study investigated the psychosocial functioning of patients and a close relative pre- and post-allogeneic and autologous bone marrow transplantation (BMT). All patients (n = 28) undergoing BMT in a 1 year period, and their relatives, were interviewed 1 week pre-transplant and at 3, 6 and 12 months post-BMT, using quantitative and qualitative measures. Pre-transplant data revealed a high level of anxiety (61% with moderate to severe anxiety), and a low level of depression (14% with moderate to severe depression). Twelve patients died in the study period. For the surviving patients there was a statistically significant improvement in physical, psychological and social functioning. Most relatives (88%) reported considerable psychological distress pre-transplant and at 3 months post-transplant, but this was largely resolved by 12 months post-transplant. Significant correlations between the relative's distress and patient's physical and psychological wellbeing were observed at 3 months post-transplant, but not at the other assessment points. The findings from this study will help in counselling patients and their relatives as to what to expect in the year following BMT.

Adaptation, Psychological↗
PubMed2002

Health-related quality of life in WHO class II-III obese men losing weight with very-low-energy diet and behaviour modification: a randomised clinical trial.

OBJECTIVE: To study health-related quality of life responses to marked weight loss in WHO Class II-III (body mass index (BMI) > or = 35 kg/m2) obese men. DESIGN: An 8 month randomised clinical trial with a 4 month weight loss programme (10 weeks on a very-low-energy diet (VLED) and 17 behaviour modification visits) in the treatment group and no intervention in the control group. SUBJECTS: Nineteen men (mean age 45.9 y, mean BMI 39.3 kg/m2) in the treatment group and 19 men (47.2 y, 39.4 kg/m2) in the control group. MEASUREMENTS: Weight and questionnaires measuring health-related quality of life (RAND 36-Item Health Survey 1.0 and obesity-related psychosocial problems scale). RESULTS: In the treatment group, the mean (s.d.) weight loss was 17.0 (7.4)% at the end of the 4 month therapy. At the end of follow-up, nearly 6 months after the end of VLED in the treatment group, the average maintained weight loss was 13.9 (7.8)% of baseline weight. The control group was weight stable throughout the study. During treatment, there was only transient improvement in general health, bodily pain, mental health, emotional role functioning and vitality (all increases in the scores were not statistically significant). Improvements in physical functioning, social functioning and obesity-related psychosocial problems were maintained until the end of follow-up. The treatment group also reported improvement in perceived health in the past year. There was only minor fluctuation in questionnaire scores in the control group. CONCLUSION: The short-term and maintained health-related quality of life effects of weight loss may differ. Marked weight loss in WHO Class II-III obese men leads to improvements in physical functioning, social functioning, obesity-related psychosocial problems, and perceived health; these improvements were maintained at 4 month post-intervention follow-up.

Adolescent↗
PubMed1998

Validation of spiral computed tomography for dental implants.

OBJECTIVES: To investigate the accuracy of 2DCT orthoradial reformatted images from spiral computed tomography (CT) for pre-surgical planning of dental implants in proximity to the mental foramen. METHODS: Eight cadaver heads were imaged by spiral CT (S/Xpress, Toshiba-America, Tustin, CA) with 1 mm thick axial slices by 1 mm/sec of table feed. The image data set was transferred to a networked computer workstation. Using computer graphics the data was analysed with 2D orthoradial reformatting using the ToothPix (Cemax, Fremont, CA, USA) protocol. Linear measurements were made by two oral radiologists independently from the superior border of the mental foramen to the crest of the alveolar process and from the inferior border of the mental foramen to the mandibular inferior border. The soft tissues were removed and physical measurements made using a 3 Space (Polhemus, Colchester, VT) electromagnetic digitizer with a personal computer running Windows 95. RESULTS: The differences between the measurements on orthoradial 2DCT images and the physical measurements were not statistically significant (P > 0.05). CONCLUSIONS: Two-dimensional spiral CT imaging allows highly accurate measurements for dental implant placement in proximity to the mental foramen. Computer graphics software, using reformatted reconstruction, is suitable for implant planning.

Aged↗
PubMed2006

Theory of single photon on demand from a single molecule source.

We consider the theory of single photon on demand from a two level atom or molecule source. Using optical Bloch equations and the generating function formalism we investigate three approaches to single photon control: (i) the square laser pulse; (ii) the square modulation of absorption frequency; and (iii) the rapid adiabatic following approach investigated in the experiments of Brunel et al., Phys. Rev. Lett., 1999, 83, 2722. We discuss the conditions for obtaining the maximum of the probability of emission of a single photon and a pair of photons, under the constrains of finite field strength and finite interaction time with excitation field. We obtain analytical expression for the probability of emitting zero, one, and two photons for the square pulse, and discuss semi-classical and strongly quantum limiting cases. Numerical results obtained from the generating function formalism are compared with experimental results showing that the two level system approach is suitable for the description of cryogenic temperature single molecules, and that experiments were conducted very close to the optimal conditions.

Absorption↗
PubMed1971

Molecular-sieve chromatography and electrophoresis in polyacrylamide gels.

1. The absolute electrophoretic mobilities of eight proteins have been measured at pH8.76, I 0.05, in polyacrylamide gels of 20 different compositions at 10 degrees C. 2. The partition coefficients of these proteins have been determined chromatographically under the same conditions by using columns of granulated polyacrylamide gel prepared simultaneously. 3. The electrophoretic mobilities are an exponential function of the gel concentrations when the latter are corrected for water uptake. The constants of this function have been determined by curvefitting methods. They have been shown to be related to the free solution mobility and to the mean molecular radius respectively. 4. The reduced mobilities have been shown to be a linear function of the partition coefficients by statistical analyses. 5. The physical significance of the relation between electrophoretic mobility and chromatographic phase distribution in gel media is discussed in the context of these results.

Acrylamides↗
PubMed1997

Muscular activity of the shoulder and neck region during sustained and intermittent exercise.

Sustained isometric contractions of the neck and shoulder muscles in laboratory conditions are often assumed to be representative of muscular load in occupational tasks. The present study aims to investigate whether differences can be found between these contractions and those in intermittent tasks. Ten subjects performed forward flexions of the right arm during three tests to the limit of endurance: (1) a sustained contraction; (2) an intermittent contraction with a cycle time of 10 s and a duty cycle of 0.7; and (3) the same intermittent contraction with the possibility of changing the shoulder angle during relaxation. Muscular activities of the upper trapezius, deltoid pars anterior and medialis and infraspinatus were registered using surface electromyography, and changes in the signal were quantified by root mean square (RMS) and mean power frequency (MPF) values. During the continuous test, highly significant changes in both parameters were found for the four muscles. Significant changes were found during both intermittent conditions, although to a lesser degree than in the continuous test. Significant differences between the regression coefficients of the sustained test and the two intermittent tests were found on all occasions: for RMS and MPF of the four muscles. Significant differences were also found regarding the intermittent tests. The test in which no variation in limb position was allowed during relaxation caused a more pronounced MPF decrease for the trapezius (P < or = 0.01), which was confirmed by the subjective scores of perceived exertion and a higher RMS increase (P < or = 0.01) for the middle part of the deltoid. The intermittent condition with changes in shoulder angle showed more MPF decrease for the deltoid, significant for the middle part (P < or = 0.05), not significant for the anterior part and a larger RMS increase for infraspinatus (P < or = 0.05). It can be concluded that the latter condition represents more the trapezius and deltoid activity as in occupational tasks.

Adolescent↗
PubMed1999

Influence of different intragastric stimuli on triggering of transient lower oesophageal sphincter relaxation in the dog.

Gastro-oesophageal reflux in the dog is mainly caused by transient lower oesophageal sphincter relaxation (TLOSR), the major stimulus for which is distension of the stomach. The possibility that liquid and/or acid sensors in the proximal stomach reduce the incidence and/or shorten the duration of TLOSR was addressed in the present study. Manometric recordings of the pharynx, oesophagus, lower oesophageal sphincter and stomach were made in awake dogs equipped with an oesophagostomy. TLOSRs were induced by insufflation of air or infusion of liquid nutrients with varying pH. Intragastric distension with air provoked TLOSRs with a significantly shorter duration than those seen after distension with liquid (4.3 +/- 0.5 vs 9.6 +/- 0.3 sec; P < 0.05). There were fewer TLOSRs at high intragastric pH (pH 5.0: 3.1 +/- 0.5/90 min) than at low pH (pH 1.5: 5.5 +/- 0.9/90 min, P < 0.05). Successfully propagated peristalsis following a TLOSR was more common after stimulation with liquid than with air. It can be concluded that there are H(+)-sensing mechanisms in the stomach which stimulate triggering of TLOSR. In addition, the reduced duration of TLOSR during air insufflation shows that the physical state of the distending stimulus can affect the patterning of TLOSR.

Animals↗