Biomedical subjects

L C Bernard

Publications and source records attributed to L C Bernard.

12 recordsLinked to original sources

PubMed2001

Interaction of human immunodeficiency virus type 1 Vpr with the HHR23A DNA repair protein does not correlate with multiple biological functions of Vpr.

The virion-associated Vpr protein of human immunodeficiency virus type 1 (HIV-1) alters cell cycle progression from the G2 phase, influences the virus in vivo mutation rate, and participates in the nuclear translocation of viral DNA. While many Vpr-interacting proteins have been identified, the functional relevance of these interactions remains to be thoroughly documented. We have explored the contribution of the interaction of HIV-1 Vpr with HHR23A, a cellular protein implicated in DNA repair, to the known phenotypes of Vpr. The association of Vpr with HHR23A required the core region of Vpr, which encompasses the two alpha-helical structures of the protein. No binding of HHR23A was detected with the Vpr and Vpx proteins of other primate lentiviruses. HIV-1 Vpr variants containing single amino acid substitutions in each alpha-helix and deficient for binding to HHR23A were isolated. The functional characterization of these Vpr variants indicated that binding to HHR23A did not correlate with the ability of Vpr to induce cell cycle arrest, even though it was previously proposed that HHR23A is a mediator of the Vpr-induced G2 arrest. Also, the Vpr-HHR23A interaction did not influence the HIV-1 in vivo mutation rate. Finally, Vpr and HHR23A are both localized in the nucleus, but no correlation was observed between the nuclear targeting of Vpr and the interaction with HHR23A. Further analysis is needed to determine the functional role(s) of the Vpr-HHR23A association during the HIV-1 life cycle.

Amino Acid Substitution↗

PubMed2000

3'-Azido-3'-deoxythymidine (AZT) and AZT-resistant reverse transcriptase can increase the in vivo mutation rate of human immunodeficiency virus type 1.

How antiretroviral drug resistance influences human immunodeficiency virus type 1 (HIV-1) evolution is not clear. This study tested the hypothesis that antiretroviral drugs such as 3'-azido-3'-deoxythymidine (AZT) can influence the in vivo mutation rate of HIV-1. It was observed that AZT can increase the rate of HIV-1 mutation by a factor of 7 in a single round of replication. In addition, (-)2',3'-dideoxy-3'-thiacytidine (3TC) was also found to increase the mutation rate of HIV-1 by a factor of 3. It was also found that HIV-1 drug-resistant reverse transcriptase (RT) variants can influence the in vivo mutation rate. Replication of HIV-1 with AZT-resistant RTs increased the mutation rate by as much as a factor of 3, while replication of HIV-1 with a 3TC-resistant RT (M184V) had no significant effect on the mutation rate. It was observed that only high-level, AZT-resistant RT variants could influence the in vivo mutation rate (i.e., M41L/T215Y and M41L/D67N/K70R/T215Y). In total, these observations indicate that both antiretroviral drugs and drug resistance mutations can influence the in vivo mutation rate of HIV-1.

Animals↗

PubMed1996

The differential effects of simulating malingering, closed head injury, and other CNS pathology on the Wisconsin Card Sorting Test: support for the "pattern of performance" hypothesis.

We investigated the effects of faking bad on the Wisconsin Card Sorting Test, comparing the performance of simulating malingerers (M; n = 24) to controls (C; n = 21), closed head-injured patients (CHI, n = 70), and patients with mixed CNS pathology other than CHI alone (CNS; n = 89). Stepwise discriminant functions achieved good accuracy (91-96%), sensitivity (58-100%), and specificity (92-100%) in differentiating simulating malingerers from these groups. The Categories score was a consistent significant independent discriminating variable. Categories alone could differentiate between the M and C groups. However, in discriminating between simulating malingerers and both CHI or CNS patients, more complex patterns of performance emerged, consisting of relatively poorer performance ratios on Categories compared to Perseverative Errors. This supported the Pattern of Performance theory of the effects of simulating malingering on neuropsychological tests, which holds that people simulating malingering do more poorly on obvious vs. subtle tasks compared to people with verified brain damage. Due to the difficulty of tracking one's performance on several different indices simultaneously, known patterns of performance for patients with verified brain dysfunction should be very difficult to fake, even with coaching.

Journal Article↗

PubMed1993

Malingering on neuropsychological memory tests: potential objective indicators.

We evaluated five potential indicators of malingering on the Rey Memory Test (RMT), Hebb's Recurring Digits (HRD), the Wechsler Memory Scale-Revised (WMS-R), the Complex Figure Test (CFT), and the Auditory Verbal Learning Test (AVLT). Fifty-seven subjects were assigned randomly to either a control group or a simulated malingering group. Two indicators-discriminant functions derived from the WMS-R and from the CFT/AVLT-achieved classification accuracy of 88% and 86%, respectively, without misidentifying controls as malingerers. Among the remaining indicators, there were problems with the recommended RMT cut-off, but it and the HRD show some promise. Subjects who simulated malingering did so by suppressing performance on tasks that involve recall as well as recognition memory and are relatively easy, but not obviously so.

Adult↗

PubMed1993

Discriminating between simulated malingering and closed head injury on the Wechsler Memory Scale-Revised.

We tested the hypothesis that malingering is distinguished by poorer performance on recognition relative to recall tasks by evaluating the ability of discriminant functions to distinguish between 89 subjects simulating malingering and 44 subjects with a history of closed head injury (CHI) on the Wechsler Memory Scale - Revised (WMS-R). Functions with good accuracy in discriminating between simulated malingerers and controls in prior studies did not have adequate specificity when applied to the CHI group. A newly derived discriminant function achieved overall classification accuracy of 79% for the malingering versus CHI groups on cross-validation, with 79% sensitivity (true positives for malingering) and 80% specificity (true negatives for closed head injured). A complex performance pattern on seven WMS-R subtests distinguished malingering subjects from those with CHI, but did not support the recognition versus recall hypothesis. The malingering pattern involved: (a) power performance on two relatively (but inconspicuously) easy tasks dependent on immediate recall (Visual Reproduction I and Visual Memory Span); (b) better performance on two relatively (but inconspicuously) easy tasks dependent on immediate recall (Visual Paired Associates I and Digit Span); (c) poorer performance on two relatively difficult delayed tasks (Logical Memory II and Visual Paired Associates II); and (d) better performance on another difficult task involving delayed recall (Visual Reproduction II).

Journal Article↗

PubMed1991

The detection of faked deficits on the Rey Auditory Verbal Learning Test: the effect of serial position.

The ability of subjects to fake deficits on the Rey Auditory Verbal Learning Test (AVLT) was evaluated. Subjects were randomly assigned to one of two malingering groups - one with a financial incentive (N = 30) and one without (N = 28) - or a control group (C) (N = 28), and a group of closed head injury patients (CHI) (N = 18) was matched on age, sex, and education level. The two malingering groups did not differ significantly and were combined into a single malingering group (M) (N = 57). There was a significant serial position (the pattern of "recency" and "primacy" effects in recall) by group interaction effect, which may be the most promising indicator of deliberate distortion. When only level of performance was examined, the M group could fake believable deficits, but when the serial position effect was examined, it revealed that this was accomplished by suppression of recall from the first third of the word list (reducing the "primacy effect"), a recall pattern which did not occur in either the C or CHI group and may be an indication of malingering.

Clinical Trial↗

PubMed1990

Assessing the validity of memory complaints: performance of brain-damaged and normal individuals on Rey's task to detect malingering.

Rey (1964) proposed a brief screening test to assess the validity of memory complaints and hypothesized that the ease of the task would mislead malingerers to perform more poorly even than persons with impaired memory due to brain injury. Lezak (1983) suggested cut-offs, but only one empirical report on Rey's task could be located in the literature. That study by Goldberg and Miller (1986) supported Lezak's cut-offs; however, the criterion groups were psychiatric and mentally retarded inpatients. In the present study, Rey's test, along with other neuropsychological tests designed to determine various types of memory dysfunction, was administered to brain-damaged (n = 18) and comparison (n = 16) groups. The results again generally supported Lezak's cut-offs.

Adult↗

PubMed1990

Prospects for faking believable memory deficits on neuropsychological tests and the use of incentives in simulation research.

The vulnerability of several neuropsychological memory tests--the Wechsler Memory Scale--Revised, Complex Figure Test, Auditory Verbal Learning Test, and Rey Memory Test--to faked deficits was evaluated. Subjects were randomly assigned to one of three conditions: Control (n = 28), Malingering with a financial incentive (n = 30), and Malingering without a financial incentive (n = 28). Overall, the performance of the Malingering Groups was not significantly different from one another, but both groups were significantly poorer than Controls. Discriminant functions with a reduced set of predictors correctly classified about 75% of cases in both the Control and the combined Malingering Groups on cross-validation. The results suggest that neuropsychological memory tests are vulnerable to faked deficits, and that recognition tasks are disproportionately affected. The use of incentives in simulation research is also discussed.

Adult↗

PubMed1989

Halstead-Reitan Neuropsychological Test performance of black, Hispanic, and white young adult males from poor academic backgrounds.

Forty-five black, Hispanic, and white young adult males of average range intellectual functioning, from poor academic backgrounds but with average academic achievement scores, were administered the Halstead-Reitan Neuropsychological Test Battery (HRNB). The results indicated that the Impairment Index, based on the traditional cutoffs, did not overly mis-represent this group as impaired. However, using the traditional cutoffs, the percentage in the impaired range on individual subtests ranged from 11% to 71%, suggesting caution when subtests are used apart from the battery (specifically, problems with the Finger Tapping test cutoffs are discussed). The three racial/ethnic groups did not have significantly different Impairment Indexes, and there were few significant differences between them on individual subtests.

Journal Article↗

PubMed1982

Sex-role factor identification and sexual preference of men.

This extension of Bernard and Epstein (1978) compared 117 homosexual and 83 heterosexual men matched on age, education, job category, and race on 43 variables including personality items, age and education, plus additional interest and behavioral items not in the prior study. Five varimax factors were extracted: (a) domestic activities, (b) practical and recreational activities and "masculine" interests, (c) conservatism, (d) boldness, and (e) openness. Composite factor scores were estimated and group means compared. Homosexual men appeared to be more open than heterosexual men, though equally bold. Homosexual men also appeared to engage in more domestic activities, whereas heterosexual men appeared to engage in more practical and recreational activities, have more traditional "masculine" interests, and be more conservative. It was concluded that interest and behavioral factors, in conjunction with personality factors, provide a more comprehensive understanding of the sex-role identification of men.

Adult↗

PubMed1978

Sex role conformity in homosexual and heterosexual males.

Nine principal components were extracted from the scores of 26 homosexual and 26 heterosexual males matched on age, education, occupation status, and sampling frame on Adjective Check List, Bem Sex Role Inventory, Chapin Social Insight Test, Experience Inventory, and Sixteen Personality Factor Questionnaire scales selected to represent a variety of "masculine" and "feminine" sex role attributes. The four most general varimax factors, accounting for 48% of the total variance, were: I) "Feminine Openness," II) "Masculine Boldness," III) "Reflection," and IV) "Novelty Seeking." Factor scores were constructed and indicated that the homosexual sample was significantly more identified with Factor I (p < .00l; 17% of total variance). There was no significant difference between the samples on Factor II, nor on the remaining two general factors which were not sex typed.

Journal Article↗

PubMed1978

Androgyny scores of matched homosexual and heterosexual males.

Twenty-sex white homosexual males and 26 white heterosexual males were matched on age, education, occupational level, and sampling frame. One-half of the pairs were volunteers, and one-half were paid for participating. Masculinity, femininity, and androgyny scores were obtained on the Bem Sex Role Inventory. The homosexual sample was "androgynous", and the heterosexual sample was highly "masculine sex typed," by definition (Bem, 1974). This difference was tested by a derived "androgynyscore" and was significant (p less than .05).

Adolescent↗