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Biomedical subjects

S O'Connor

Publications and source records attributed to S O'Connor.

At least 55 records · Page 3Linked to original sources
PubMed1997

Street youth, their peer group affiliation and differences according to residential status, subsistence patterns, and use of services.

This study characterizes subcultural differences within an inner-city street youth population. Variations in residential status, subsistence patterns, and service utilization according to peer group affiliation were explored. A brief structured interview was administered to 752 youth, ages 12 to 23 years, who had been living on the streets for two or more consecutive months, or who were fully integrated into the "street economy." Subjects were recruited for the study using a stratified probability sampling design, with 30% recruited from community-based service sites and 70% from street locations and at natural "hang-outs." Five street youth groups were identified: "punks/skinheads," "druggies," "hustlers," "gang members," and "loners." The results demonstrated unique patterns with respect to places stayed/slept, means of financial support and economic subsistence, and use of available services according to peer group affiliation. The implications of these findings and recommendations for future research and service provision are discussed.

Adolescent↗
PubMed1996

Parental influences on the dieting beliefs and behaviors of adolescent females in New Zealand.

PURPOSE: To investigate parental influences on the weight perceptions and the dieting beliefs and behaviors of adolescent girls. METHODS: The subjects were 232, 8th and 9th grade girls attending an urban New Zealand secondary school. Data on girls' perceptions of being thinner, beliefs about dieting, and their dieting behavior were obtained via a number of self-report scales. RESULTS: An association was found between girls' perceptions of the impact of being thinner, dieting beliefs, dieting behaviors, and parental encouragements to diet (p < .0001). In general, parental dieting practices did not influence dieting beliefs except that fathers' dieting behavior was associated with some aspects of girls' dieting behaviors. CONCLUSIONS: Parental encouragement to diet was associated with a wide range of weight loss behaviors, including the more extreme measures. In addition, having a father who dieted was associated with participation in a number of the dieting behaviors.

Adolescent↗
PubMed1996

Bartonella vinsonii subsp. berkhoffii subsp. nov., isolated from dogs; Bartonella vinsonii subsp. vinsonii; and emended description of Bartonella vinsonii.

Two bacterial strains, one isolated from the blood of a dog with valvular endocarditis and one isolated from the blood of a healthy dog, were similar to Bartonella species, as determined by a number of phenotypic criteria, including growth characteristics, biochemical reactions, and cell wall fatty acid composition. The results of 16S rRNA gene sequence similarity studies confirmed that these strains are closely related and belong in the genus Bartonella and that Bartonella vinsonii is their closest relative (the 16S rRNA of isolate 93-C01T [T = type strain] was 99.37% identical to the 16S rRNA of the type strain of B. vinsonii, the 16S rRNA of isolate G7464 was 99.61% identical to the 16S rRNA of the type strain, and the 16S rRNAs of the dog isolates were 99.77% identical to each other). The 16S rRNAs of both strains contained a 12-base insertion that was not present in the 16S rRNA of the type strain of any Bartonella species. DNA relatedness tests revealed that these strains were related at the species level to the type strain of B. vinsonii. They were, however, significantly more closely related to each other than to B. vinsonii. On the basis of their unique 16S rRNA sequence insertion, their preferentially high level of relatedness, and their similar origins (dogs), we believe that strains 93-C01(T) and G7464 should be placed in a separate subspecies of B. vinsonii, for which we propose the name B. vinsonii subsp. berkhoffii subsp. nov. The type strain of B. vinsonii subsp. berkhoffii is strain 93-C01 (= ATCC 51672). The description of B. vinsonii is emended to accommodate the new subspecies, and B. vinsonii subsp. vinsonii is described.

Animals↗
PubMed1996

Genetic analysis of the resting electroencephalographic power spectrum in human twins.

Most twin studies have provided evidence for genetic effects on the electroencephalogram (EEG). In two twin studies, monozygotic (MZ) cotwin covariance for EEG power was greater than expected for additive gene actions, as compared with dizygotic (DZ) cotwin covariance. These findings were attributed to complex gene interactions, termed emergenesis. In the present study of 53 MZ and 38 DZ twin pairs departures from the additive genetic model were tested on resting EEG power. Total spectral power and the quotient of (beta band power)/(total power) both fit gene interaction models significantly better than did additive genetic models. These findings support the previous findings of MZ covariance for EEG power as much greater than DZ covariance; these findings can be explained entirely by the additive effects of genes. This pattern of twin covariances could be due to gene interactions but also to greater MZ than DZ environmental covariance.

Adult↗
PubMed1996

Alcohol effects on the heritability of EEG spectral power.

To estimate the effects of a moderate dose of alcohol on heritability of the EEG power spectrum, 53 monozygotic and 38 like-sexed dizygotic Caucasian twin pairs (aged 30.0 +/- 7.0 years) were studied. Subjects were asked not to drink alcohol for 2 days and to fast after midnight before a protocol of: (1) a low fat meal at 8:00 AM; (2) a baseline EEG recording; (3) ingestion of alcohol over 10 min, which raised the breath alcohol concentration to 0.057 +/- 0.017% (SD); followed by (4) a postalcohol EEG recording 35.1 +/- 5.7 (SD) min after the start of drinking. One previous study (Propping, P., Hum. Genet. 35: 309-334, 1977) found that heritability (H2), the fraction of total variance in the EEG power that is attributable to genetic influences, increased after alcohol administration. In the current study, H2 of log-transformed, body-weight-adjusted spectral band power increased after alcohol for the theta-, alpha-slow, alpha-fast, beta-slow, and beta-fast bands (from an average of 0.47 to an average of 0.80). The increase in heritability was accompanied by a significant decrease in the within-pair differences of monozygotic cotwins for all of the same frequency bands except beta-fast. Because within-pair differences are expected to contain only environmental factors for the genetically identical individuals, it was concluded that alcohol decreases environmental variation of EEG power spectral density, causing the increase in H2.

Adult↗
PubMed1995

Street youth in Los Angeles. Profile of a group at high risk for human immunodeficiency virus infection.

OBJECTIVE: To characterize an urban street youth population, their self-reported rates of drug use, and their involvement in behaviors that put them at risk for infection with the human immunodeficiency virus. DESIGN: A brief structured interview was administered to 409 youths who had been living on the streets for 2 or more consecutive months, or who were fully integrated into the "street economy." SETTING: Thirty percent of the sample were recruited from community-based service sites and 70% were recruited from street locations and at natural hangouts. PARTICIPANTS: Youths were aged 12 to 23 years; 74% were male, 48% were ethnic minorities, 72% were homeless, 14% were gang affiliated, 20% were involved in drug dealing, 43% were engaged in survival sex (ie, the exchange of a sexual favor for money, food, a place to stay, clothes, and/or drugs), and 40% were homosexual or bisexual. RESULTS: Seventy percent of the youths were sexually active, with an average of 11.7 sexual partners (past 30 days). Youths with multiple sexual partners were more likely to have had a previous sexually transmitted disease (P < .01), to use drugs during sex (P < .001), and to be involved in survival sex (P < .001). Marijuana (55%), methamphetamine (62%), and crack (38%) were the drugs of choice, with 30% of the sample reporting injecting drug use (58% of this subset reported injecting drug use within the past 30 days). Substance-abusing youth were 3.6 times more likely to use drugs during sex, 2.2 times more likely to engage in survival sex, and 2.5 times more likely to have been diagnosed as having a sexually transmitted disease. CONCLUSIONS: High-risk sexual and drug use behaviors were prevalent and interrelated in this urban street youth sample. This suggests the need for new and innovative educational promotions and prevention interventions targeted to this population.

Adolescent↗
PubMed1995

Multi-center N400 ERP consistency using a primed and unprimed word paradigm.

A word priming paradigm involving primed, unprimed, and non-word experimental conditions was used to elicit event-related potentials (ERPs) in normal, young adult males in identically equipped electrophysiology laboratories located in 6 different cities in the USA. Analyses of the average amplitude of a specified latency window containing the N400, the N400 peak amplitude, or the latency of the N400 peak amplitude found no differences among laboratory locations. The shape of the N400 ERP wave form was also found to be highly correlated across laboratory sites for each experimental condition. Comparison of the data with analogous word priming paradigms revealed similar patterns for the N400 components and response times in both the primed and unprimed experimental conditions. These findings suggest that the data from all 6 laboratory locations are consistent with each other and are congruous with those found in other N400 studies and will permit pooling of subject data for future research.

Adolescent↗
PubMed1994

B-cell non-Hodgkin's lymphoma cell line (Karpas 1106) with complex translocation involving 18q21.3 but lacking BCL2 rearrangement and expression.

A B-cell non-Hodgkin's lymphoma (B-NHL) cell line (Karpas 1106) with an unusual three-way translocation involving 18q21.3 has been derived from a patient with mediastinal lymphoblastic B-NHL. Although conventional cytogenetics showed a derivative 18q-identical to that seen in cases with t(14;18)(q32.3;q21.3), no translocations of either chromosome 14 could be detected. Instead fluorescent in situ hybridization analysis using a chromosome-18 paint showed that the segment 18q21.3-18qter had become sandwiched on a derivative chromosome X between segments Xqter-c-Xq28 and 13q12-qter, with the centrometric site of 18q21.3 subband juxtaposed to the X sequences. Pulsed-field DNA blots failed to detect rearrangement of the BCL2 gene. Conventional DNA blots using a variety of restriction digests and both 5' and 3' BCL2 and FVT 1 probes also failed to detect rearrangement in Karpas 1106. A rearranged fragment seen only in HindIII digests with 5' BLC2 probes may represent a local microalteration, which is either a mutation or small deletion involving the HindIII site as seen in other cases of B-NHL. Neither BCL2 RNA nor BCL2 protein expression were detected. These and other data suggest that genes at 18q21.3, other than BCL2 and FVT1, may be targets for translocation in certain subgroups of B-NHL.

Adult↗
PubMed1994

Heritable features of the auditory oddball event-related potential: peaks, latencies, morphology and topography.

Baseline auditory ERP data from a larger study of the genetic determinants of the response to alcohol were collected from 59 monozygotic (MZ) twin pairs and from 39 same-sex dizygotic (DZ) twin pairs who drank socially. Three methods for measuring genetic influence on the ERPs were applied. First, based on maximum-likelihood estimates, the heritability of conventional peak amplitude and latency of N1 and P3 components was computed for each of 16 lead locations using tests of the significance of heritability based on intraclass correlations. P3 amplitude provided the strongest results, distributed symmetrically over caudal leads, and implied gene dominance as the mode of genetic transmission for the P3 component. A substantial genetic influence on N1 latency suggested a mixture of additive and dominance effects in the left fronto-temporal regions. N1 amplitude measures trended towards significant heritability, but none was observed for P3 latency. The second method used the maximum of the cross-correlation function to compare wave form shape in a lead-by-lead analysis of data from cotwins. Genetic influence was apparent in both target and non-target ERP responses, with a fronto-central topography of significant results. The third method reduced all spatial and temporal ERP differences from a pair of twins to a single scalar number for each response. Distributions of this global measure revealed significant genetic influence on both non-target and target ERPs. A post hoc analysis of the effect of gender on the heritability of N1 or P3 peaks and latencies revealed no statistically significant observations in this sample of young adult twins.

Acoustic Stimulation↗
PubMed1994

P300 differences between non-alcoholic young men at average and above-average risk for alcoholism: effects of distraction and task modality.

1. P300 event-related electroencephalographic potentials were recorded from 79 young adult males, cross-classified with respect to the presence/absence of a family history of alcoholism (FHA) and the presence/absence of a personal history of antisocial personality (ASP) disorder. P300s were elicited using visual and auditory oddball tasks. Each oddball task was repeated with a tracking task added as a distractor. 2. In general, distraction increased the latencies and reduced the amplitudes of P300s elicited by the oddball stimuli. The P300 latency increase occurred only in low risk ASP- and FHA- groups. There was no adaptive increase in P300 latency in the higher risk ASP+ and FHA+ groups. 3. Group differences in P300 were restricted to visual tasks. No interpretable group differences in P300 latency or amplitude were found during the auditory tasks.

Acoustic Stimulation↗
PubMed1994

Reduced P3 amplitudes are associated with both a family history of alcoholism and antisocial personality disorder.

1. Previous research has demonstrated that the amplitude of the P3 component of the event-related electroencephalographic potential (ERP) is influenced by the presence/absence of a family history of alcoholism (FHA). The present study extended this line of research by examining the P3 effects of both FHA and antisocial personality disorder (ASP) in a 2 x 2 factorial design. 2. The task required subjects to judge the orientation of an infrequently-occurring outline drawing, representing an aerial view of a human head. 3. Analyses of P3 amplitudes elicited by this drawing revealed reductions attributable to the effects of both FHA and ASP, but not their interaction. These effects were most apparent at frontal electrode sites. Analyses of P3 latency revealed no consistent pattern of findings. However, the interval between P3 and manual reaction time was shorter in the ASP+ group relative to the ASP-group.

Adult↗
PubMed1994

Frontal P300 decrements in antisocial personality disorder.

Event-related potentials (ERPs) were recorded from 83, 21- to 25-year-old nonalcoholic men varying in alcoholism vulnerability due to the presence/absence of an alcoholic family history or a personal history of antisocial personality disorder. ERPs were elicited by a visual oddball task in which the target was presented more frequently than the nontarget, in order to elicit impulsive or perseverative responding. Analyses of N200 and P300 revealed no group differences in the nontarget response. However, analyses of the target response revealed a significantly smaller P300 in the antisocial personality (ASP)+ group compared with the ASP- groups. The P300 decrement was limited to frontal electrode sites and is interpreted as indicating the presence of subtle anterior brain dysfunction among ASP+ subjects.

Adult↗