Is the increase in renal papillary phospholipid biosynthesis a protective mechanism against injury?

Mercuric chloride (HgCl2) is a well-known renal toxic that causes acute renal failure. The effect of HgCl2 treatment and the protection by thyroxine were studied in rat renal papilla (P), outer medullary inner stripe (OMIS), outer medullary outer stripe (OMOS) and cortical phospholipids (PhLs). HgCl2 brought about an increase in the total phospholipid content in P and OMIS but a drop in OMOS and cortex. Only phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) accounted for such changes. Thyroxine, injected on HgCl2-treated rats, partially reversed the effect of the toxic metal in P and OMIS while completely reversed the PtdCho drop in OMOS and cortex. However, the hormone failed to recover the sphingomyelin increase in P, the PtdEtn shortage in OMIS, OMOS and partially reversed the drop in the cortex. When thyroxine was injected without toxic treatment, no effect was observed in the phospholipid content of any kidney zone. Results obtained by using 32P as a precursor to study the PhL de novo synthesis were consistent with those of the phospholipid content. Thus a radioactivity increase--associated with PtdCho and PtdEtn--was observed in the kidney zones where said endogenous PhLs had risen. But in OMOS and cortex, where PtdCho and PtdEtn had dropped, they were also accompanied by a decrease in radioactivity. The thyroxine-induced recovery phase also paralleled the phospholipid content results with those of the de novo synthesis. We suggest that the decrease in the renal phospholipid de novo synthesis may constitute one biochemical explanation of the selective renal toxic effect exerted by HgCl2 and that the increase observed in the renal phospholipid metabolism--induced by the toxic treatment in OMIS and P--may represent a protective mechanism of these zones against toxic injury. Moreover, recovery promoted by thyroxine treatment in OMOS and cortex was accompanied by the reversion of the corresponding PtdCho decrease induced by HgCl2.

Child physical abuse and aggression: preliminary findings on the role of internalizing problems.

OBJECTIVE: To test the prediction that the interaction of physical abuse and internalizing problems will heighten levels of aggressive behavior in a group of disruptive children. METHOD: Fifty-two clinic-referred disruptive children (aged 7 through 15 years) were assessed in terms of history of physical abuse, internalizing behavior problems (rated by parents), and aggressive behavior (rated by parents, teachers, and clinic staff). RESULTS: Physically abused children with co-occurring high levels of internalizing problems (based on a median split) exhibited significantly higher levels of aggression as rated by parents (p < .000) and teachers (p < .020) and a trend toward heightened aggression as rated by staff (p < .08). The patterns were similar across the three independent informants and remained regardless of age, gender, or race. CONCLUSIONS: Physical abuse was related to heightened levels of aggression only in those children who also had emotional difficulties. Results lend some support to a transactional model of the development of aggression, suggesting that problems arise out of interactions between child factors (such as internalizing problems) and adverse family experiences (such as physical abuse).

Salivary testosterone and cortisol in disruptive children: relationship to aggressive, hyperactive, and internalizing behaviors.

OBJECTIVE: To test predictions that basal salivary testosterone and cortisol are related to antisocial and internalizing behaviors, respectively, and that cortisol moderates the testosterone-aggression relationship. METHOD: Saliva samples were assayed to determine testosterone and cortisol levels in 40 clinic-referred disruptive children (aged 7 through 14 years) who were rated on aggression, inattention/overactivity, and internalizing behavior by parents, teachers, and clinic staff members. RESULTS: Results indicated significant positive relationships between testosterone and staff-rated aggression and between cortisol and parent-rated internalizing behavior. A significant negative relationship was found between cortisol and staff-rated inattention/overactivity. No interactions between testosterone and cortisol were found. These results were maintained regardless of age, racial background, height, weight, diagnosis, or medication status. CONCLUSIONS: Results suggest moderate relationships between testosterone and observed aggression, and between cortisol and emotional behaviors, in a group of disruptive children. Cortisol did not moderate the testosterone-aggression relationship in this population.

The relationship of sweat gland count to electrodermal activity.

This study assessed whether greater skin conductance activity at the distal versus medial site (Scerbo, Freedman, Raine, Dawson, & Venables, 1992) is attributable to a greater number of active (open) sweat glands at the distal site. The number of sweat glands was measured using the Palmar Sweat Index (PSI). Twenty-four subjects were exposed to 10 auditory stimuli. Electrodes were placed on the fore and middle fingers of each hand, using distal sites on one hand and medial sites on the other. The PSI was measured at the medial and distal phalanges adjacent to the electrode placement sites. The distal site contained more open and total sweat glands. Open gland count had the strongest correlations with skin conductance. Multivariate analyses of covariance revealed that site effects for nonspecific and orienting response frequency and trials to habituation were associated with site differences in open glands. Skin conductance measures and the PSI reveal greater electrodermal activity at the distal site. In addition, the number of open glands may be a useful measure related to electrodermal response frequency when polygraph measurement is unavailable.

Cognitive-perceptual, interpersonal, and disorganized features of schizotypal personality.

While two factors are currently thought to underlie individual differences in schizotypal personality, three factors may best explain schizotypal traits. This study used confirmatory factor analysis to assess five competing models of schizotypal personality in the general population: null model, one-factor model, simple two-factor model, Kendler two-factor model, and three-factor model. The computer program LISREL was used to analyze Schizotypal Personality Questionnaire subscale scores that reflect the nine traits of schizotypal personality. The scores were obtained from (1) a sample of 822 undergraduates and (2) a replication sample of 102 subjects drawn from the community. Results indicate replicable support for a three-factor model reflecting cognitive-perceptual, interpersonal, and disorganized latent factors. Low intercorrelations between the first two factors and the lack of fit by a one-factor model are partially inconsistent with recent notions that a single vulnerability dimension underlies schizotypal personality. It is argued that future investigations should assess the correlates of all three schizotypal factors in clinical and nonclinical samples in addition to the two more traditional factors. It is hypothesized that three factors of schizophrenic symptomatology observed in recent studies may reflect an exaggeration of three analogous factors found in the general population.

Impaired eye tracking in undergraduates with schizotypal personality disorder.

Qualitative ratings of smooth pursuit eye movements were significantly worse for 14 undergraduates with DSM-III-R schizotypal personality disorder than for 18 comparison subjects. The groups did not differ on IQ, indicating that deficits in smooth pursuit eye movements in schizotypal personality disorder are not a function of cognitive deficits.

A major effect of recording site on measurement of electrodermal activity.

Although the medial phalanx has been recommended as the preferred site for recording skin conductance activity, a review of articles published in Psychophysiology indicates that a large minority (34%) of studies employ the distal phalanx. Informal observations also suggest that the distal site may be more reactive than the medial site. This study formally tests this observation by recording skin conductance from both medial and distal phalanges. Twenty-four right-handed subjects (12 male, 12 female) were exposed to a series of 10 orienting and defensive stimuli. Electrodes were placed on the fore and middle fingers of each hand, with distal sites used on one hand and medial sites on the other for each subject. Skin conductance amplitudes were 3.5 times larger at distal than medial sites (p less than .002), while skin conductance levels were 2.08 times larger at distal sites (p less than .0005). A significant Site X Stimulus interaction (p less than .025) indicated that the distal site was more sensitive to habituation over trials and to increases in skin conductance amplitudes with increasing stimulus intensity than the medial site. On the basis of these findings it is recommended that distal sites be used in preference to medial sites in the recording of skin conductance activity.

Reduced lateralization in verbal dichotic listening in adolescent psychopaths.

One possible explanation for previous findings of abnormal linguistic processing in psychopaths is that they are less lateralized for verbal processes. This study tests the hypothesis that adolescent psychopaths show evidence of reduced lateralization on a verbal dichotic listening task. Four self-report and behavioral measures of psychopathy were used to define psychopathy using cluster analytic techniques in 40 juvenile offenders aged 13 to 18 years. Psychopaths were found to have reduced ear asymmetries relative to nonpsychopaths, a result indicating reduced lateralization for verbal material. The effect does not appear to be mediated by group differences in age, ethnic background, IQ, overall performance, left-handedness, selective attention to one ear, or interhemispheric transfer deficits. This result suggests that the previous finding by Hare and McPherson is robust, provides some preliminary validity for the assessment of psychopathy before age 18, and indicates initial support for the utility of cluster analytic techniques in the assessment of psychopathy.

Reward dominance and passive avoidance learning in adolescent psychopaths.

This study tests predictions that adolescent psychopaths are hyperresponsive to rewards (Quay, 1988) and deficient in passive avoidance learning (Newman & Kosson, 1986). Forty male adolescent juvenile offenders were divided into psychopaths and nonpsychopaths using cluster analysis. Subjects were administered a passive avoidance learning task which required learning when to respond to cards associated with either reward or punishment. Results showed a greater responsivity to reward in psychopaths, with no group differences in passive avoidance errors. Results lend support to the view that psychopaths tend to focus on the prospect of reward under conditions of mixed incentives and, when sufficiently motivated, are capable of improved performance. Together with findings of recent psychophysiological studies, these results suggest that adolescent psychopaths may have latent abilities which could have treatment implications.