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Biomedical subjects

O White

Publications and source records attributed to O White.

69 records · Page 4Linked to original sources
PubMed1988

Chromosomal aberrations and sister-chromatid exchanges in lymphocytes from coke oven workers.

To test whether coke oven workers, an occupational group known to be at increased cancer risk, manifest increased peripheral blood chromosomal aberration frequencies, we obtained samples from a group of 30 steelworker volunteers, who had worked several years at coke oven jobs. Exposure estimates were made using measurements of work place atmospheric coal tar pitch volatiles and work histories. No statistically significant positive regression of chromosomal aberrations on exposure estimates was found. The data from the coke oven workers were also compared with the obtained concurrently and employing precisely the same laboratory protocol from a group of male Brookhaven National Laboratory employees. The coke oven workers as a group were found to have statistically significantly elevated frequencies of chromatid aberrations and of sister-chromatid exchanges.

Aneuploidy↗
PubMed1988

Standardization and analysis of digitized photographic data in the longitudinal documentation of cataractous growth.

Age-related cataract formation in man can be documented with slit and retroillumination photographs. With digitization and image analysis of such photographs a cataract may be characterized by a frequency distribution of picture elements over a 255 step gray scale spectrum. Transition from a clear to a cataractous lens may be manifested as a change from a unimodal, Gaussian to a multimodal, non Gaussian frequency distribution respectively. How should one compare and contrast these two distributions, so to accurately describe the extent and significance of a change in lens opacification? The in vitro system of cold cataract formation in the rabbit lens was used as a model of the much slower process of age-related cataract formation in man. As in the human lens undergoing progressive opacification, the frequency distribution (number of pixels vs. intensity of gray) for a digitized image of a clear lens at 26 degrees C is unimodal and Gaussian; that of a fully developed cold cataract at 10 degrees C is multimodal and non-gaussian. In spite of the increasing multimodality of the frequency distribution as the temperature dropped and the cataract grew in density and size, the mean gray density proved to be a valid and useful measure to characterize the distribution and to compare different unaligned images. The Wilcoxon Rank Sum Test proved to be useless in comparing the frequency distributions from cataract images because it proved to be too sensitive to subtle changes in the degree of opacification. Anomalous behavior of the opacification process--i.e. clarification as well as opacification of the lens during cold cataract formation caused all pairs to appear statistically significantly different when in appearance there was no difference. The mean of the frequency distribution is less sensitive to this anomalous behavior and is useful as a comparative index. The method of calculating the threshold of significant change in the mean density of a cataract image is presented.

Animals↗
PubMed1986

Topographic correspondence between total and non-freezable water content and the appearance of cataract in human lenses.

Eight intracapsular and 18 extracapsular human surgical specimens were stereophotographed. Each lens was divided into 10 areas, separating those which appeared transparent from those that showed opacities. Samples weighing 6-12 mg from each area were investigated. The total water content was determined by thermogravimetric analysis; the freezable water content was measured by differential scanning calorimetry. The difference between the two provided the non-freezable water content. Graphic presentation illustrates the correspondence of high total water, low non-freezable water content with location of the turbidity in the lens. Pairwise, statistical comparison shows that in intracapsular human surgical specimens the non-freezable water content in the clear areas of both cortex and nucleus was significantly greater than in the opaque areas.

Body Water↗
PubMed1986

Freezable and non-freezable water content of cataractous human lenses.

Twenty-nine cataractous human lenses between the ages of 36 and 93 were investigated. The total water content of cortex and nucleus were obtained by vacuum dehydration. The freezable water content was measured by differential scanning calorimetry. The non-freezable water content was obtained by difference. To measure the extent that syneresis contributes to cataract formation, an excess function was designed. The excess function represents the changes that occur, for example, in non-freezable water content due to cataractogenesis. It is calculated as the difference between the non-freezable water content of a normal lens and that of a cataractous lens of the same age. On the average, there is 7% less non-freezable water in the cortex of a cataractous lens than in the cortex of a normal lens. The corresponding number for the nucleus is 9%. This represents 29 and 36% changes, respectively, in the cortex and nucleus due to syneresis during cataractogenesis.

Adult↗
PubMed1985

Validity and reproducibility of the Cooperative Cataract Research Group (CCRG) cataract classification system.

The validity and reproducibility with which six classifiers [one experienced (L.T.C.), and five novices (W.G., F.G., W.W., J.W. and O.W.)] used the CCRG cataract classification system was assessed. The validity of index classifications was assessed by computing sensitivities and pairwise interclass correlations between experienced and novice classifiers using the former's classification as the standard. The number of unordered combinations of terms in the CCRG's classification was reduced by combining cortical terms according to the CCRG's accepted system of staged simplification. The number of combinations of terms at each stage is as follows: Stage I (greater than 1000); II (127); III (63); IV (15); V (7); VI and VII (3) and VIII (2). Excellent agreement was obtained between the experienced and novice classifiers for Stages VII and VIII of the classification, good agreement for Stages V and VI and poor agreement for Stages IV, III and II (sensitivities of 97, 96, 72, 59, 40, 24 and 20% respectively). Good agreement was also achieved for the classifications of single lenticular regions, except for subcapsular regions. The intra- and interobserver reproducibility was assessed by computing the Kappa statistic to (1) compare classifications between novice observers and (2) compare repeat classifications made by the same observer by viewing the same cataract once on each of three different days. The novice classifiers had excellent intraobserver reproducibility for Stages VII and VIII (Kappas of 0.87 and 0.97 respectively), good reproducibility for Stages IV, V and VI (Kappas of 0.53, 0.62 and 0.62, respectively) and marginal reproducibility for stages II and III (Kappas of 0.39 and 0.40, respectively). The intraobserver reproducibility of the experienced classifier was superior to the others for virtually all characteristics with excellent reproducibility for Stages IV, V, VI, VII and VIII with Kappas of 0.79, 0.90, 1.0, 1.0 and 1.0, respectively and good reproducibility for Stages II and III (Kappas of 0.55 and 0.64, respectively). These results indicate that the simplified CCRG cataract classification system (Stages IV-VIII) passes the minimum standards for reproducibility. The performance of the experienced classifier far exceeds the minimum standards and indicates the feasibility of improving classifier performance with training and practice.

Cataract↗
PubMed1984

Classification of human senile cataractous change by the American Cooperative Cataract Research Group (CCRG) method: II. Staged simplification of cataract classification.

One thousand nine hundred and seventy-six cataracts extracted intracapsularly were classified according to the system adopted by the Cooperative Cataract Research Group (CCRG) Consortium. A nine-stage protocol for simplifying the classification data is presented. The method of simplifying the basic CCRG classification emphasizes anatomic similarities among lenses. Simplification is indicated when small numbers of cataracts in any class provide insufficient statistical power to allow detection of scientifically or clinically important differences in rates between comparison groups, if such differences exist; however, simplification unavoidably obscures the anatomic, biochemical, and biophysical features of individual cataracts. Age-specific characteristics of this population of 1976 cataracts are used to demonstrate the effects of the simplification process. The preponderance of mixed cataracts and the relative scarcity of pure cataracts are documented, and the implications of these numbers for cataract research are presented.

Age Factors↗
PubMed1984

Classification of human senile cataractous change by the American Cooperative Cataract Research Group (CCRG) method: III. The association of nuclear color (sclerosis) with extent of cataract formation, age, and visual acuity.

Nineteen hundred and seventy-six immature human cataracts extracted intracapsularly were classified according to the Cooperative Cataract Research Group (CCRG) method of cataract classification. Data on cataract location and extent, nuclear color, preoperative visual acuity, age, and sex were organized and stored in the PROPHET system. The data were examined for relationships between nuclear color (sclerosis) and the age of the cataractous lens, the extent of opacification in seven anatomical regions including the degree of nuclear opacification and the preoperative visual acuity. Nuclear color correlates with age in a curvilinear manner. Nuclear yellowing increases gradually with increasing nuclear opacification, but the color change is so slight as to be useless for the purposes of inferring the intensity of nuclear opacification from the color of the nucleus. There is no association between the extent of anterior cortical, equatorial cortical, posterior cortical, subcapsular or supranuclear opacification, and nuclear color. Nuclear color impairs vision only for the range dark yellow through black. These data justify the recommendation that nuclear color be abandoned as the single index of the severity of any type of senile cataractous change.

Age Factors↗
PubMed1971

Analysis of Clostridium botulinum toxigenic types A, B, and E for fatty and carbohydrate content.

Lyophilized, 48-hr log-phase vegetative cells were extracted with chloroform-methanol (2:1, v/v) and ethanol-ether (3:1, v/v) and then saponified with methanolic KOH. Gas-liquid chromatography of the methyl esters of extractable fatty acids revealed distinctive "pattern profiles" of Clostridium botulinum toxigenic types "A," "B," and "E." C. perfringens type "A" and Escherichia coli strain "B" were also studied in a similar manner and were found to give pattern profiles which were distinct even from those obtained for the C. botulinum microorganisms. Amino sugar content of the five microorganisms was determined by using a Beckman amino acid analyzer. The molar ratio of glucosamine to that of galactosamine was found to be of further assistance in distinguishing the individual microorganisms.

Amino Acids↗
PubMedDate not supplied

Short repeats and IS elements in the extremely radiation-resistant bacterium Deinococcus radiodurans and comparison to other bacterial species.

Computer analysis of the complete genome of Deinococcus radiodurans R1 has shown that the number of insertion sequences (ISs) and small noncoding repeats (SNRs) it contains is very high, and comparable with those of Escherichia coli. IS elements and several families of SNRs are described, together with their possible function in the D. radiodurans genome.

Amino Acid Sequence↗
PubMedDate not supplied

Occupational exposure to coke oven emissions from 1979-1983.

Breathing zone samples of benzene soluble fraction of total particulate matter (BSFTPM) were obtained for coke oven workers at a selected steel plant from 1979-1983. Analysis of the 1622 samples, collected for compliance with the 1976 OSHA coke oven emissions standard, indicated that there were significant differences in exposures to BSFTPM among the following variables: job classifications, batteries where the employees were stationed, shifts during the work day, and years and quarters of the year when samples were collected. In comparison to studies conducted prior to 1976, exposures to BSFTPM in the current study are consistently lower for every job classification. However, even in 1983, a large percentage of the workers in many of the sampled job classifications had BSFTPM concentrations that were above 0.150 mg/m3, indicating that current engineering controls and work practices are not sufficient to provide exposure levels below the recommended standard.

Air Pollutants, Occupational↗
PubMedDate not supplied

Background and initial case studies into the effects of prospective memory training.

Two preliminary case studies are presented introducing the technique of Prospective Memory Training (PMT) as a potential means to manage severe memory impairments. PMT involves repetitive administration of prospective memory tasks in which the patient is asked to initiate a specific action at a future designated time. Background information relevant to the concept of prospective memory is presented. Possible theoretical foundations for PMT are also discussed.

Adult↗
PubMedDate not supplied

An investigation of the effects of prospective memory training.

A within-subject operant design was used to evaluate the efficacy of prospective memory training in a 51-year-old brain-injured male with a severe memory impairment. Training consisted of repetitive administration of prospective memory tasks whereby the subject was given actions to perform at specified future times. The length of time between task administration and task execution was systematically lengthened. Probes were taken evaluating generalization to performance on naturalistic, real-life prospective memory tasks and to performance on retrospective memory or recall measures. Results suggested a significant and steady increase in the subject's prospective memory ability over time; however, changes were not experimentally controlled, thus the data are descriptive in nature. Methodological limitations and issues pertinent to the future investigation of prospective memory are discussed at length, in the hope of encouraging further evaluation of this preliminary, promising technique.

Activities of Daily Living↗
PubMedDate not supplied

Children with burn injuries: purposeful activity versus rote exercise.

OBJECTIVE: This study was designed to compare measures of pain when children with burn injuries were engaged in a purposeful activity, specifically a play activity, versus rote exercise. METHOD: Two 6-year-old children participated in a study using a single-subject, randomized multiple treatment design to compare two conditions: purposeful activity and rote exercise. Data were gathered for each session on four dependent measures: number of repetitions of therapeutic exercise completed, number and type of overt distress behaviors displayed, scores on self-report scales of pain intensity, and overall enjoyment of the activity. RESULTS: Visual inspection of the graphed data suggested that, early in the rehabilitation process, the use of a play activity in comparison to rote exercise yielded better outcomes in terms of all four dependent measures. Additionally, the data implied that there may be a point later in the rehabilitation of a child with a burn injury when rote exercise may be as effective as play activities in meeting therapeutic goals. CONCLUSION: This study supports the belief that purposeful activity can yield results equal to or better than those achieved using rote exercise. Replication of this study is warranted, and the development is indicated of a measure of overt behavioral distress that is more appropriate than those currently available for children with burn injuries.

Burns↗
PubMedDate not supplied

Comparison of Sensory Profile scores of young children with and without autism spectrum disorders.

OBJECTIVES: The purpose of this study was to describe the sensory-based behaviors of young children with autism as reported by their parents on the Sensory Profile. Factor scores of children with autism were compared with those of children without autism. METHOD: The Sensory Profile questionnaire was completed by parents of 40 children with autism 3 through 6 years of age and parents of 40 children without autism 3 through 6 years of age. RESULTS: The performance of children with autism was significantly different from that of children without autism on 8 of 10 factors. Factors where differences were found included Sensory Seeking, Emotionally Reactive, Low Endurance/Tone, Oral Sensitivity, Inattention/Distractibility, Poor Registration, Fine Motor/Perceptual, and Other. CONCLUSION: Findings from the study suggest that young children with autism have deficits in a variety of sensory processing abilities as measured by the Sensory Profile. Further research is needed to replicate these findings, to examine the possibility of subgroups on the basis of sensory processing, and to contrast the sensory processing abilities of children with other disabilities to those of children with autism.

Autistic Disorder↗