Classification of physical activity intensities using a wrist-worn accelerometer in 8-12-year-old children.

BACKGROUND: Population-specific accelerometer cut-points are required to accurately determine the accumulation of physical activity of various intensities. OBJECTIVES: A calibration study was conducted (i) to determine the cut-points for the ActiGraph GT3X+, non-dominant, wrist-mounted accelerometer in children aged 8-12 years and (ii) to compare classification accuracies among the accelerometer's three axes and vector magnitude (VM) values. METHODS: Forty-five children aged 8-12 years performed up to seven activities while wearing accelerometers on their non-dominant wrist. Activities were performed in a summer day camp setting, represented free-living activities, and lasted for 10 min with minutes 5-8.5 used for analysis. Direct observation and percentage of heart rate reserve were used to determine activity intensity. RESULTS: Receiver operator characteristic (ROC) analyses resulted in area under the curve values of all three axes and VM ranging 0.82-0.89, 0.80-0.83, 0.62-0.67 and 0.86-0.89 for light, moderate, vigorous and moderate-to-vigorous activity intensities. Additionally, regression analyses resulted in prediction equations with R2 values ranging from 0.70 to 0.77. CONCLUSION: Results found comparable activity intensity classification accuracies from the ActiGraph GT3X+ wrist-worn accelerometer to previously published studies. Based on ROC and regression analyses, activity intensities can be distilled from this accelerometer using axis 1, axis 2 or VM values with similar classification accuracy.

Complexity IX. Closure over the organization of a scientific truth.

The specificity of human knowledge allow one to construct specific truths about human behavior. A structural notation and language for describing a complex hierarchically organized biological system was developed for the explicit purpose of analyzing the origins of health and disease. A specific application of these concepts to a specific patient (such as an individual suffering from the heritable disease, sickle cell anemia) requires a systematic formulation of a scientific truth. No universal law is applicable. The value of a clinical truth for the patient, as well as for the physician and society, is substantial. This value has moral, ethical, and legal weight. Both physics and chemistry use a universal external invariant reference system. Human beings and other living organisms function by an internal reference system that is neither invariant nor universal. In order to address the complexity of scientific truths within living systems, a mathematical graph is constructed from observations, descriptions, and symbolizations of the relevant human scientific activities and is placed in mutual coreference with three philosophical theories of truth. Consistency within the referencing relations of the graphic object creates an image of complex truths. When mapped over degrees of internal organization, the structural consistencies can form hierarchically transitive relations (many-to-one) creating redundancies that confirm one-another. Both structural and dynamic information can be composed within the graphic framework. The redundancies intrinsic to the degrees of organization notation, semantics, and syntax augment one another in the search for scientific truth. The degree of certitude emerging from structural implications increases in relation to the number of hierarchical degrees of organization invoked to represent the various behaviors of complex systems (as illustrated by the sickle cell anemia example). The successful synthesis of the complex image (or complex simple) of a scientific truth approaches the Heideggerian notion of identity in the sense that A = A and A is A.

Neuropsychological performance of HIV-1 infected men with major depression. HNRC Group. HIV Neurobehavioral Research Center.

This study sought to determine if human immunodeficiency virus-type 1 (HIV-1) infected depressed men were more likely to be neuropsychologically impaired than their nondepressed counterparts. Subjects were 47 HIV-1 infected men who met DSM-III-R criteria for current major depressive disorder (MDD) and 47 HIV-1 infected nondepressed male controls (M age = 34.2 years) equated on HIV-1 disease severity, demographics, and drug use. The psychiatric interview included the Structured Clinical Inventory for the DSM-III-R, and Hamilton Rating Scale for Depression. The neuropsychological battery included tests covering 8 functional domains based on an expanded Halstead-Reitan Battery. The medical assessment included a history and physical examination, immunologic staging, and evaluation of prescription and recreational drug use. Prevalence of global neuropsychological impairment in the two groups (depressed vs. control) did not differ [53% vs. 38% respectively; chi 2(1, N = 94) = 2.11, p > .05]. While syndromically depressed patients performed less well than nondepressed individuals on memory tests [delayed retention portions of the Story Memory Test: F(1,91) = 5.34, p < .05; and Figure Memory Test: F(1,90) = 4.16, p < .05], the majority of depressed participants (64%) did not have clinically impaired memory. No relationship between neuropsychological impairment and severity of depression was observed. The results suggest that, while HIV-1 infected men with major depression may perform more poorly than nondepressed men on some aspects of memory tasks, they are not more likely to evidence clinically significant neurocognitive impairment.

Memory for verbal information in individuals with HIV-associated dementia complex. HNRC Group.

Patterns of memory performance were examined for 9 participants with HIV-associated dementia (HAD), 15 HIV-seropositive participants without dementia, and 15 HIV-seronegative controls. Episodic and semantic memory were assessed using the California Verbal Learning Test, the Boston Naming Test, and Verbal Fluency tests. The HAD group showed deficits in episodic memory, with relative sparing of semantic memory. In addition, results suggest a retrieval deficit in HAD rather than a deficit in retention of information. This pattern is consistent with the presence of a subcortical dementing process and supports findings from previous neuropathological, neuroimaging, and neuropsychological studies suggesting that subcortical brain dysfunction is frequently associated with HIV disease (e.g., Navia, Jordan, & Price, 1986).

Allotetraploid hybrids between citrus and seven related genera produced by somatic hybridization.

We have developed an efficient protoplast-fusion method to produce somatic hybrid allopolyploid plants that combine Citrus with seven related genera, including four that are sexually incompatible. In this paper we report the creation of 18 new allotetraploid hybrids of Citrus, including ten among sexually incompatible related genera, that may have direct cultivar potential as improved citrus rootstocks. All hybrids were confirmed by cytological and RAPD analyses. If fertile, the attributes of these hybrids may be amenable to further genetic manipulation by breeding at the tetraploid level. Wide somatic hybridization of Citrus via protoplast fusion bypasses biological barriers to the natural allopolyploidization of Citrus, and creates new evolutionary opportunities that would be difficult or impossible to achieve by natural or conventional hybridization.

Decline in working memory associated with HIV infection. HNRC Group.

HIV infection has been associated with decline in a number of cognitive functions that are components of 'working memory'. Thus, tests of working memory that require the interaction of these components may be particularly sensitive to cognitive dysfunction that arises from HIV infection. To assess this possibility, working memory was examined in 147 HIV-seropositive (HIV+) and 38 HIV-seronegative (HIV-) males using the Reading Span Test and the Digit Span subtest from the Wechsler Memory Scale-Revised (WMS-R). Speed of information processing, a component of some working memory tasks, was assessed with a version of the Sternberg Memory Scanning task. Results indicated that symptomatic HIV+ subjects were impaired relative to HIV- control subjects on the Reading Span and Digit Span tests. Asymptomatic and mildly symptomatic HIV+ groups exhibited a trend toward impairment on these tests, and on the whole, a greater proportion of HIV+ subjects than HIV- subjects were impaired. The groups did not differ significantly in information processing speed. These results indicate that deficits in working memory are apparent in at least a subset of HIV-infected individuals. These deficits are most apparent in symptomatic HIV+ individuals, but the decline may begin during the asymptomatic phase of infection.

Stress and depressive symptoms prospectively predict immune change among HIV-seropositive men. HIV Neurobehavioral Research Center Group.

LIFE stress, mood, and other psychosocial factors may help to explain variability in HIV (human immunodeficiency virus) disease progression. Attempts to support this notion empirically have produced mixed findings; several studies report a positive relationship between psychosocial factors and various indicators of disease progression or immune function (e.g., Evans et al. 1992; Goodkin et. al. 1992), whereas others have failed to detect any association (e.g., Perry et. al. 1992).

Neuroleptic treatment of HIV-associated psychosis. HNRC group.

The aim of this rater-blinded randomized study was to evaluate the efficacy and side effects of haloperidol and thioridazine in the treatment of new-onset psychosis in HIV-positive individuals. Participants were 13 men who had no history of psychosis prior to infection with HIV, and whose psychosis was not attributable to delirium or to non-HIV-related organic factors. Participants were evaluated at baseline after at least one month without neuroleptic treatment and then weekly for six weeks of the experimental treatment using several rating scales. The mean daily dose in chlorpromazine equivalents was 124 mg. Both neuroleptics produced modest but significant reduction in overall level of psychosis and in positive symptoms, but not in negative symptoms. All the haloperidol-treated patients developed extrapyramidal side effects and required treatment with anticholinergic medication, whereas three of the five thioridazine-treated patients had noticeable side effects. We make recommendations for the treatment of HIV-associated psychosis with neuroleptics.

HIV-associated psychosis: a study of 20 cases. San Diego HIV Neurobehavioral Research Center Group.

OBJECTIVE: Psychosis is an uncommon but serious complication of infection with HIV. This article presents the results of a study of HIV-infected individuals with psychosis. METHOD: The authors evaluated 20 HIV-infected men who had noniatrogenic new-onset psychosis without delirium, current substance abuse, or previous psychotic episodes. Clinical, neuropsychological, CSF, magnetic resonance imaging, and neuropathologic assessments were made. A comparison group consisting of 20 nonpsychotic HIV-infected men matched to the psychotic subjects with respect to age, race, years of education, and Centers for Disease Control HIV stage was also evaluated. RESULTS: The psychotic patients differed from the nonpsychotic comparison subjects in having significantly higher rates of past stimulant and sedative/hypnotic abuse or dependence and, at follow-up, a significantly higher rate of mortality. They also showed a trend toward greater global neuropsychological impairment. CONCLUSIONS: New-onset psychosis may be, at least in part, a manifestation of an HIV-associated encephalopathy.

Identification of psychobiological stressors among HIV-positive women. HIV Neurobehavioral Research Center (HNRC) Group.

This research describes major stressors in the lives of women who have been infected with the human immunodeficiency virus (HIV). Thirty-one HIV antibody positive (HIV+) women infected primarily through heterosexual contact participated in a two hour semi-structured interview detailing the circumstances, context, and consequences of all stressful life events and difficulties experienced within the preceding six months. Qualitative methods of data analyses were utilized (Miles & Huberman, 1984). HIV-related life events and difficulties were classified into primary and secondary stressors based on the stress process model (Pearlin et al., 1981). Problems arising directly from one's seropositivity were defined as primary stressors. Stressful life events and difficulties occurring in other role areas were defined as secondary stressors. Six categories of HIV-related stressors were identified and quantified. Primary stressors were health-related, and included both gynecological problems (e.g., amenorrhea) and general symptoms of HIV infection (e.g., fatigue). Secondary stressors related to child and family (e.g., future guardianship of children), marital/partner relations (e.g., disclosure of HIV+ status), occupation (e.g., arranging time-off for medical appointments), economic problems (e.g., insurance "hassles"), and social network events (e.g., death of friends from AIDS). This research indicates that HIV-positive women are exposed to multiple stressors; some may be viewed as unique to women, whereas others may be considered common to both sexes. Identification of stressors has implications for the design of medical and psychiatric interventions for women.

Somatic hybrid plants from sexually incompatible woody species: Citrus reticulata and Citropsis gilletiana.

Allotetraploid intergeneric somatic hybrid plants between Citrus reticulata Blanco cv. Cleopatra mandarin and Citropsis gilletiana Swing. & M. Kell. (common name Gillet's cherry orange) were regenerated following protoplast fusion. Cleopatra protoplasts were isolated from an ovule-derived embryogenic suspension culture and fused chemically with leaf-derived protoplasts of Citropsis gilletiana. Cleopatra mandarin and somatic hybrid plants were regenerated via somatic embryogenesis. Hybrid plant identification was based on differential leaf morphology, root-tip cell chromosome number, and electrophoretic analyses of phosphoglucose mutase (PGM) and phosphohexose isomerase (PHI) isozyme banding patterns. This is the first somatic hybrid within the Rutaceae reported that does not have Citrus sinensis (sweet orange) as a parent, and the first produced with a commercially important citrus rootstock and a complementary but sexually incompatible, related species.

Intergeneric somatic hybrid plants of Citrus sinensis cv. Hamlin and Poncirus trifoliata cv. Flying Dragon.

Intergeneric somatic hybrid plants between 'Hamlin' sweet orange [Citrus sinensis (L.) Osbeck] and 'Flying Dragon' trifoliate orange (Poncirus trifoliata Raf.) were regenerated following protoplast fusion. 'Hamlin' protoplasts, isolated from an habituated embryogenic suspension culture, were fused chemically with 'Flying Dragon' protoplasts isolated from juvenile leaf tissue. The hybrid selection scheme was based on complementation of the regenerative ability of the 'Hamlin' protoplasts with the subsequent expression of the trifoliate leaf character of 'Flying Dragon.' Hybrid plants were regenerated via somatic embryogenesis and multiplied organogenically. Hybrid morphology was intermediate to that of the parents. Chromosome counts indicated that the hybrids were allotetraploids (2n=4x=36). Malate dehydrogenase (MDH) isozyme patterns confirmed the hybrid nature of the regenerated plants. These genetically unique somatic hybrid plants will be evaluated for citrus rootstock potential. The cell fusion, selection, and regeneration scheme developed herein should provide a general means to expand the germplasm base of cultivated Citrus by intergeneric hybridization with related sexually incompatible genera.

Fashion alienation: older adults and the mass media.

A self-administered questionnaire including questions related to fashion alienation, frequency of use of mass media for fashion information, and demographics was completed by 209 "50-plus" aged consumers in Northern California. Fashion alienation was measured using ten separate statements related to 1) degree of identification with fashion symbols in the media and 2) feelings of social and economic estrangement from fashion. Two of the statements produced significant regression models. In both statements, age was positively related to fashion alienation, and there was an inverse relationship between frequency of use of media for fashion information and fashion alienation. The data provide implications for a conceptual distinction between information and meaning processing with regard to fashion.

Studies on the de novo biosynthesis of NAD in Escherichia coli. The separation of the nadB gene product from the nadA gene product and its purification.

Quinolinic acid (pyridine 2,3-dicarboxylic acid) which is an immediate precursor of the pyridine nucleotides, is synthesised from L-asparate and dihydroxyacetone phosphate in Escherichia coli. Extracts from certain nadB mutants complement the extracts prepared from all nadA mutants for the enzymic synthesis of quinolinate. Using the complementation assay, the quinolinate synthetase B protein has been purified more than 300-fold. The quinolinate synthetase B protein exists in all nadA and nadC mutants examined. The quinolinate synthetase A protein was present in all nadC mutants and most (but not all) nadB mutants. The facile separation of the wild-type quinolinate synthetase A and B proteins out of a nadC mutant suggests that quinolinate synthetase does not exists as a tightly bound complex. The partially purified quinolinate synthetase is inhibited by physiological concetrations of NAD and NADH but not by NADP or NADPH.