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At least 811 records · Page 45Linked to original sources
PubMed1986

Relationships of quantitative structure-activity to comparative toxicity of selected phenols in the Pimephales promelas and Tetrahymena pyriformis test systems.

The relative toxic response of 27 selected phenols in the 96-hr acute flowthrough Pimephales promelas (fathead minnow) and the 48- to 60-hr chronic static Tetrahymena pyriformis (ciliate protozoan) test systems was evaluated. Log Kow-dependent linear regression analyses revealed that the data from each test system consisted of two linear equations. The less toxic chemicals form a relationship which models polar narcosis; these chemicals are slightly more active than the baseline toxicity of nonionic narcotic chemicals. The more toxic chemicals form a relationship which models uncoupling of oxidative phosphorylation. Regression analysis of fathead minnow toxicity (log LC50 (mol/liter] vs Tetrahymena toxicity (log BR (mmol/liter] showed good correlation between the two systems. An exception appears to be 4-nitrophenol, which is more active in the Tetrahymena system than in the fathead minnow and lies outside the 95% confidence interval. Reanalysis following deletion of 4-nitrophenol results in the equation log LC50 = -0.9192 (log BR) -3.5035; n = 26, r2 = 0.887.

Animals↗
PubMedDate not supplied

Double-blind, multicenter evaluation of the efficacy and tolerability of diclofenac dispersible in the treatment of acute soft-tissue injuries.

In a randomized, double-blind, parallel-group, multicenter study, the efficacy and tolerability of diclofenac dispersible were compared with placebo in the treatment of acute soft-tissue injuries. Patients seen within 48 hours of a soft-tissue injury received either diclofenac dispersible 50 mg or placebo three times daily for 3 to 7 days, with paracetamol allowed as a rescue analgesic. Of a total of 253 recruited patients. 247 patients (122 in the diclofenac dispersible group and 125 in the placebo group) were eligible for tolerability assessment and 229 patients (115 diclofenac dispersible and 114 placebo) were eligible for efficacy analysis. In general, median reductions in the intensities of pain at rest, on movement, and on local pressure (as measured on 100-mm analog chromatic continuous scales) were greater with diclofenac dispersible than with placebo after treatment (differences did not reach statistical significance). At the center that recruited the largest number of patients, the initial median levels of pain at rest and on movement were considerably lower than those at the other centers. On reanalysis of the pain data without this center, a significant difference favoring diclofenac dispersible over placebo was noted for pain on movement and on local pressure (P < or = 0.044). With respect to daily assessment of pain severity, more patients in the diclofenac dispersible group had none or mild pain while fewer had moderate or severe pain during the early posttreatment days; this treatment difference versus placebo reached statistical significance on days 3 and 4 (P < or = 0.045).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMedDate not supplied

Sources of variation in the mutagenic potency of complex chemical mixtures based on the Salmonella/microsome assay.

Twenty laboratories worldwide participated in a collaborative trial sponsored by the International Programme on Chemical Safety on the mutagenicity of complex mixtures as expressed in the Salmonella/microsome assay. The U.S. National Institute of Standards and Technology provided homogeneous reference samples of urban air and diesel particles and a coal tar solution to each participating laboratory, along with samples of benzo[a]pyrene and 1-nitropyrene which served as positive controls. Mutagenic potency was characterized by the slope of the initial linear component of the dose-response curve. Analysis of variance revealed significant interlaboratory variation in mutagenic potency, which accounted for 57-96% of the total variance on a logarithmic scale, depending on the sample, strain and activation conditions. Variation among replicate extractions of organic material (required for the air and diesel particles) and among replicate bioassays within the same laboratory was also appreciable. The average potencies for air and diesel particles in laboratories using Soxhlet extracts were not significantly different from those in laboratories using sonication, although there was larger interlaboratory variation for the Soxhlet method. Repeatability (which approximates the coefficient of variation within laboratories) ranged from 18 to 40% for air and diesel particles extracted using sonication, depending on the strain and activation conditions. Repeatability of Soxhlet-extracted air and diesel particles, however, ranged from about 37 to 89% including outliers and from about 11 to 31% excluding outliers. Repeatability of the coal tar sample and the 2 positive controls was in the range 18-34%. Reproducibility (which approximates the coefficient of variation between laboratories) was generally at least twice repeatability, and exceeded 100% for Soxhlet-extracted air and diesel particles, as well as 1-nitropyrene. Reanalysis of the data omitting observations of more than 1500 revertants/plate generally had little effect on these results. Elimination of outlying observations had limited impact, with the exception of Soxhlet-extracted air and diesel particles. In this case, reproducibility of bioassay results was notably improved, due largely to the omission of results for replicate extractions which varied more than 5-fold within one laboratory. Normalization of the log potency slopes for the mixtures by the corresponding slopes for benzo[a]pyrene tended to reduce this variation, although variation was increased after normalization by 1-nitropyrene. Adjustment for the percentage of organic matter extracted from the air and diesel particulate samples had little effect on variation for sonication-extracted particles, whereas variation was reduced for diesel particles and increased for air particles for Soxhlet.

Air Pollutants↗
PubMed1989

The introductory placebo washout: a retrospective evaluation.

We examined the effects of the "introductory placebo washout" technique by reanalyzing the results of a recent trial of an experimental antidepressant. At the beginning, all patients were placed on placebo in a single-blind design. Patients who were rated as placebo responders with the physician-administered Hamilton Rating Scale for Depression (HRSD) were excluded from the trial. In spite of this technique, an alternative measure of depression indicated that many patients with a positive response to placebo had been entered in the trial. In the reanalysis, elimination of these "hidden placebo responders" did not lower the final placebo response rate and actually diminished the differences observed at the end of the study between the active treatment and placebo groups. These data suggest that the introductory placebo washout may have unpredictable, possibly confounding effects on patient samples in trials of antidepressant agents.

Clinical Trials as Topic↗
PubMed1994

Five-component model of schizophrenia: assessing the factorial invariance of the positive and negative syndrome scale.

A five-component model of schizophrenia has been presented by Kay and Sevy based upon an analysis of the Positive and Negative Syndrome Scale. Kay and Sevy found factorial validity for negative and positive syndromes, and they identified excitement, depressive, and cognitive components as well. They suggested that subtypes and syndromes can be mapped along dimensions presented in their model. The present study compares the five-component solution for a new sample of 146 subjects to a reanalysis of the Kay and Sevy data. Despite divergent demographic characteristics, the two samples produce similar dimensions. Correlations of component loadings and subject scores as well as confirmatory factor analysis are presented. Discussion focuses on points of agreement and important differences in the symptoms assigned to each component. How the dimensions relate to rationally derived models of positive and negative syndromes is reviewed, and implications for subtyping and other methods of examining the heterogeneity of schizophrenia are considered.

Adult↗
PubMed1995

Memory and social skill in schizophrenia: the role of gender.

The relationship between social skill and memory was examined in a group of patients with schizophrenia and schizoaffective disorder. There were few or no differences between male and female patients in history of the illness, symptomatology, memory, and other cognitive factors, or social skill. Despite the absence of differences, impaired memory was related to poorer social skills for the women, but not the men. Reanalysis of data on social skill and memory from an earlier study (Mueser et al., 1991) revealed a similar pattern of results. The findings suggest that the contribution of cognitive factors to impaired social competence in schizophrenia may differ in men and women. Alternatively, the results may reflect sampling bias, whereby more severely ill women are studied than men, relative to their respective populations.

Adolescent↗
PubMed1985

The diffusion of innovations in hospitals. Some econometric considerations.

Empirical studies of the diffusion of innovations have not addressed adequately econometric problems that are characteristic of such analyses. Reanalysis of data for five innovations using an estimator with desirable statistical properties results in a considerably revised estimate of the impact of prospective reimbursement on diffusion.

Capital Expenditures↗
PubMed1991

Relationship between early and late normal-tissue injury after postmastectomy radiotherapy.

Factors of importance in the development of telangiectasia were investigated in a series of 229 patients who, between 1978 and 1982, received postmastectomy radiotherapy with two different fractionation schedules. Patients who developed moist desquamation had a statistically significantly increased risk of developing telangiectasia after a specific course of radiotherapy. As an example the estimated incidence of severe telangiectasia after 44 Gy in 22 fractions increases from 27% to 49% in patients who developed grade greater than or equal to 2 moist desquamation as an early radiation reaction. A reanalysis of the Aarhus data with telangiectasia as the endpoint gave an alpha/beta ratio at 2.8 Gy (95% c.l. (-0.1, 8.1) Gy) and a relative biological effectiveness (RBE) of high energy electrons relative to 8 MV photons at 0.89 (95% c.l. (0.85, 0.93)). Patients age or the occurrence of severe erythema did not predispose to telangiectasia. A similar predisposition after moist desquamation was not seen for subcutaneous fibrosis. The RBE of high energy electrons relative to 8 MV photons for this endpoint was estimated at 0.88 (95% c.l. (0.86, 0.91].

Breast Neoplasms↗
PubMed1994

The relative cellular radiosensitivity of 30 human in vitro cell lines of different histological type to high LET 62.5 MeV (p-->Be+) fast neutrons and 4 MeV photons.

It has been suggested that fast neutron therapy may have a role in the treatment of those tumours which lie within the most photon-resistant histological categories. A clinical radiobiological study by Battermann et al., however, did not support this hypothesis (Battermann, J.J. et al., Eur. J. Cancer 17: 539-548, 1981). Similarly, in a comparison of the intrinsic cellular radiosensitivity of 20 human in vitro cell lines with 4 MeV photons and 62.5 MeV (p-->Be+) neutrons, there was no correlation between RBE and photon sensitivity. However, because the range of histological cell types in this in vitro study did not include sufficient representatives of the most sensitive and resistant histological categories, it was not possible to examine the relationship between histology and the relative efficacy of fast neutrons compared with photons. The intrinsic radiosensitivity of a further 10 human in vitro cell lines has thus been measured and the results of all 30 cell lines used in a comparison of the relationship between relative neutron sensitivity and histology. These results together with those obtained by reanalysis of published data from a clinical study of the RBE of pulmonary metastases by Battermann et al. suggest that in the clinical situation, photon-resistant histology per se may not be a sufficient criterion for the choice of high LET irradiation and emphasize the need for predictive assays for individual tumours.

Energy Transfer↗
PubMed1993

Psoriasis in Australian twins.

BACKGROUND: Occurrence of psoriasis has been found to be strongly genetically controlled in Northern European and U.S. twin and family studies. OBJECTIVE: Our purpose was to assess cumulative incidence and heritability of psoriasis in the Australian population. METHODS: Australian twins reporting psoriasis on a screening questionnaire received from 3808 pairs were mailed a detailed instrument designed to validate the diagnosis, supplemented by telephone interview and examination of medical records. RESULTS: Only 94 of 160 subjects who screened positive were confirmed to have psoriasis. The cumulative incidence of confirmed psoriasis was 2% in 30- to 60-year-old subjects. The monozygotic twin casewise concordance for confirmed psoriasis was 35% (12 of 34 pairs), and the dizygotic twin concordance 12% (5 of 43 pairs), giving an estimated heritability of 80%, was similar to that found in a genetic reanalysis of three previous twin studies. A case-control analysis of psoriasis-discordant twin pairs found no evidence for influences of alcohol or coffee intake, overweight, birth weight, or personality in the origin of psoriasis. CONCLUSION: Occurrence of psoriasis in the Australian population is highly heritable, but identical twins are often discordant; the factor responsible for the onset of disease in one twin and not the other is unclear.

Adult↗
PubMed1986

Learning disabilities in individuals exposed prenatally to ionizing radiation: the Hiroshima and Nagasaki experiences.

The brain, undoubtedly the most complex organ in the mammalian body, is the culmination of a long and interrelated sequence of molecular, cellular and tissue events. Brain function hinges on the orderly progression of these, each of which must occur correctly, temporally and spatially. Impingement on any one will give rise to a less developed system of cellular connections, and hence impaired function. Moreover, the neurons of the central nervous system are not self-renewing and thus neuronal loss cannot be repaired through repopulation. Reanalysis of the data on the prenatally exposed survivors of the atomic bombing of Hiroshima and Nagasaki suggests that severe mental retardation occurs primarily, if not exclusively in the period from the 8th through the 15th week following fertilization. Within this window of vulnerability, the increase in mental retardation appears linear with dose and without threshold. More subtle functional effects also occur as reflected in diminished performance on intelligence tests and in school. These findings and their implications for space travel and regulatory agencies charged with the specification of acceptable risks should not require further elaboration in this article given the focus of the radiobiological presentations at this meeting.

Brain↗
PubMed1991

Different patterns of dissociation in unilateral spatial neglect.

The aim of this paper is to discuss the issue of dissociations found in unilateral spatial neglect according to the modality of space exploration and the nature of the task. For this purpose we present a reanalysis of the data from a recent paper of Gentilini et al. (1989) comparing visual and blindfolded exploration of a computer keyboard and discuss the performance of a left-brain-damaged patient with right visuospatial neglect and left-sided neglect dyslexia. We conclude that unilateral spatial neglect cannot be interpreted as a disruption of a single attentional mechanism, but rather it reflects impaired attentional mechanisms at several levels of cognitive processing.

Adult↗
PubMed1984

Examining the interaction effects of coping style and brief interventions in the treatment of postsurgical pain.

The present study sought to ameliorate two major deficiencies in the literature on treating response to surgery, viz., the failure to compare clearly delineated treatments, alone and in combination; and the failure to examine treatment X coping style interactions. Information imparting and brief relaxation were examined in this study as they interacted with an avoidance-sensitization coping style. No differences were found between treatments or coping styles. Sensitizers, on the other hand, were found to profit most from the relaxation training. Avoiders appeared to do well when they were left alone. The interaction effect was demonstrated for both self-report measures of pain and a behavioral measure of potency of medications ingested. The effects on self-report of pain were more evident on the second postsurgical day than on the fourth postsurgical day. The results indicate that brief relaxation training, often the only kind available to the medical psychologist dealing with surgical patients, is best confined to patients with a sensitizing coping style. Further, the results of this study, in conjunction with a reanalysis of previous studies, cast considerable doubt on information imparting when presented alone as a viable technique for reducing the distress consequent on surgery.

Adaptation, Psychological↗
PubMed1986

The use of contemporary MMPI norms in the study of chronic pain patients.

In a previous study, Ahles et al. [1] compared the MMPI results of primary fibromyalgia, rheumatoid arthritis and non-pain control participants. The purpose of the present study was to reanalyze the original data using the contemporary norms of Colligan et al. [5]. The reanalysis revealed that the pattern of group differences remained the same; however, the number of primary fibromyalgia patients classified as 'psychologically disturbed' was appreciably reduced. These data have clinical relevance in that the incidence of psychopathology in chronic pain patients may be overestimated because of the use of outdated norms. Additionally the data have theoretical relevance in that a large number of patients who present with pain in the absence of a known organic pathology do not present evidence of psychopathology.

Arthritis, Rheumatoid↗
PubMed1988

The use of high field NMR to determine homogeneity in a preparation of human C5a produced by Escherichia coli.

The polypeptide backbone of human C5a was prepared by recombinant DNA techniques. Standard biochemical analysis guided the protein separation to give a sample of C5a which was deemed homogeneous. However, nuclear magnetic resonance (NMR) studies showed the material to be significantly heterogeneous. Reanalysis by high performance liquid chromatography (HPLC) corroborated the NMR results. Further separation by HPLC and analysis by NMR spectroscopy guided the isolation of rC5a to greater than 92% purity. NMR analysis, immunochemical and biological evaluation of the impurities showed them to be C5a structural variants. These results indicate that conventional methods of protein chemistry can fail to reveal heterogeneity in recombinant proteins, and in some circumstances NMR spectroscopy can aid in their purification.

Chromatography, High Pressure Liquid↗
PubMed1990

The response of two human tumor xenografts to fractionated irradiation. The derivation of alpha/beta ratios from growth delay, tumor control, and in vitro cell survival assays.

A series of growth delay experiments was performed to derive alpha/beta ratios for two human neoplasms growing as xenografts in the hind limbs of NCr/Sed nude mice. The tumors were irradiated at 6 mm mean diameter under clamp-hypoxic conditions in one, two, four, or eight fractions, 2 fractions per day with a minimum intertreatment interval of 4 hr and a maximum overall treatment time of 3 days. The alpha/beta ratios derived for the high grade glioma U87 and the pharyngeal squamous carcinoma FaDu were 38 and 20 Gy, respectively. Comparably high values were derived from the same two tumors in a reanalysis of fractionated TCD50 data. The alpha/beta ratios were similarly high whether the TCD50 data were analyzed using the Full Effect plot or the Direct Method. For comparison, cell survival assays were performed on U87 and FaDu irradiated in vitro under plateau-phase, aerobic conditions. The alpha/beta ratios obtained were 9.2 and 15.0 Gy, respectively. Such high alpha/beta values suggest a therapeutic gain could result from the use of small doses per fraction.

Animals↗
PubMed1993

Behavioral economics and drug choice: effects of unit price on cocaine self-administration by monkeys.

The application of microeconomic theory to the experimental analysis of behavior has been termed behavioral economics. There has been an increasing interest in applying the concepts of behavioral economics to the study of drug self-administration. In a previously published experiment (Nader and Woolverton, 1992), rhesus monkeys (N = 3) were trained in a discrete-trials choice procedure and allowed to choose between intravenous injections of cocaine (0.03-1.0 mg/kg/injection) and food presentation (1 or 4 pellets; 1 g/pellet) during daily 7-h experimental sessions. When cocaine or food was available under a fixed-ratio (FR) 30 schedule, cocaine intake increased in a dose-related manner for all monkeys. When the response requirement (FR) for cocaine was differentially increased by doubling or quadrupling, the frequency of cocaine choice decreased, shifting the cocaine dose-response function to the right. The present paper is a reanalysis of data from that experiment. Several mathematical models, differentially incorporating the effects of FR, dose and number of food pellets, were compared. When cocaine consumption was analyzed using a multiple linear regression analysis with FR, dose and number of pellets as separate main effects (model I), the R2 was 0.82. When FR and dose were combined into one factor, unit price (UP, responses/mg/kg), and cocaine consumption was analyzed as a linear function of UP (model IIA), the R2 was 0.54. When cocaine consumption was analyzed as a curvilinear, negatively accelerated function of UP (model IIB), the R2 was 0.53. The difference between models I and IIA was statistically significant while models IIA and IIB were not different.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Growth charts and the assessment of infant feeding practices in the western world and in developing countries.

Changes during the past ten years in infant feeding practices are described and it is demonstrated that with the growing popularity of breast feeding, plus the later addition of solids, dietary energy intakes are substantially lower than they were. These dietary changes would appear to be associated with alterations in the detailed pattern of growth. When exclusively breast-fed, babies, if anything, grow more quickly than growth standard rates, but after 3-4 months a relative deceleration in growth velocity becomes apparent. The anthropometric and dietary findings are discussed in relation to the use of growth charts for the assessment of the adequacy of infant feeding practices in the western world and especially in the Third World. A reanalysis of data indicates that diet-related growth faltering probably does not occur in many developing country situations until later than would be suggested by growth standards currently in use.

Anthropometry↗