Mass screening for antimicrobial resistant Escherichia coli in dairy cows in northern New South Wales.

OBJECTIVE: To describe aspects of the epidemiology of antimicrobial resistance in Escherichia coli shed in the faeces of milking cows in a dairying region of New South Wales. DESIGN: A survey based on multi-stage sampling with repeated measures made within herds for estimating within-herd correlation of resistance status, and with repeated measures made on identical specimens for estimating test-retest reliability. PROCEDURE: From a population of 110 dairy herds, 30 were selected at random and from each herd between 5 and 10 faecal specimens were obtained from fresh manure pats. E coli from faecal specimens were grown on hydrophobic grid membrane filters (HGMF) and replicated onto chromogenic agar and agar containing antimicrobials (gentamicin, ampicillin, tetracycline and sulfamethoxazole). Image analysis was used to assess colony growth. Data were analysed descriptively, by generalised linear mixed models and by Taylor series linearisation to account for attributes of the survey design. RESULTS: Of the 10,279 E coli isolates assessed, 91% expressed no resistance, 7.3% were resistant to sulfamethoxazole, 3.6% to tetracycline, 2.2% to ampicillin and 0.09% to gentamicin. The most common multiple resistance phenotype was ampicillin-tetracycline-sulfamethoxazole (1.8% of isolates). Most multiple resistant isolates appeared clustered within particular herds but were too rare to obtain valid estimates of variance, confidence intervals or intra-herd correlation. The estimated proportion of isolates in the population that were susceptible to all four antimicrobials was 97% (95% CI: 91% to 100%) and 55% of cows had no resistance detected in faecal E coli (95% CI: 27% to 83%). Within-herd correlation of shedding status (any resistance pattern) was absent and test-retest reliability of the measurement system was estimated to be at the lower end of good (0.40) but increased to excellent (0.89) after excluding sulfamethoxazole resistance, which had a greater measurement error. CONCLUSION: Antimicrobial resistance was uncommon in E coli in the population of dairy cows studied. HGMF and image analysis is an effective tool for detecting rare forms of resistant E coli that are not uniformly distributed in livestock populations.

Social cognition, brain networks and schizophrenia.

BACKGROUND: A better understanding of the neural basis of social cognition including mindreading (or theory of mind) and empathy might help to explain some deficits in social functioning in people with schizophrenia. Our aim was to review neuroimaging and neuropsychological studies on social cognition, as they may shed light on the neural mechanisms of social cognition and its dysfunction in patients with schizophrenia. METHOD: A selective literature review was undertaken. RESULTS: Neuroimaging and neuropsychological studies suggest convergence upon specific networks for mindreading and empathy (the temporal cortex, amygdala and the prefrontal cortex). The frontal lobe is likely to play a central role in enabling social cognition, but mindreading and empathic abilities may require relatively different weighting of subcomponents within the same frontal-temporal social cognition network. CONCLUSIONS: Disturbances in social cognition may represent an abnormal interaction between frontal lobe and its functionally connected cortical and subcortical areas. Future studies should seek to explore the heterogeneity of social dysfunction within schizophrenia.

What's it all about, Alfie? Antisocial males in the early films of Sir Michael Caine.

Early in his film career the actor Sir Michael Caine portrayed a series of antisocial males: Harry Palmer, Alfie Elkins, Charlie Croker, and Jack Carter. The behaviours exhibited by these fictional males resemble those of "real life" patients acquiring the diagnoses of antisocial or dissocial personality disorder. Prominent among their traits is a disregard for others, a lack of guilt, and a resort to instrumental (goal directed) violence. The exhibition of antisocial conduct may be seen as a rejection of the values of the social hierarchy, the dominant or patriarchal order. Demonstrable through a defiance of dominant males and a recurrent seduction of "their" women, these Caine characters act out an Oedipal theme, repeatedly attempting subversion of the symbolic "father"-society itself. So often, the material of "real life" social behaviour is fleeting and hard to elicit reliably; however, these fictional characters provide a stable source of such exemplars, both entertaining and instructive.

Behavioural and functional anatomical correlates of deception in humans.

Brain activity in humans telling lies has yet to be elucidated. We developed an objective approach to its investigation, utilizing a computer-based interrogation and fMRI. Interrogatory questions probed recent episodic memory in 30 volunteers studied outside and 10 volunteers studied inside the MR scanner. In a counter-balanced design subjects answered specified questions both truthfully and with lies. Lying was associated with longer response times (p < 0.001) and greater activity in bilateral ventrolateral prefrontal cortices (p < 0.05, corrected). These findings were replicated using an alternative protocol. Ventrolateral prefrontal cortex may be engaged in generating lies or withholding the truth.

Investigating the functional anatomy of empathy and forgiveness.

Previous functional brain imaging studies suggest that the ability to infer the intentions and mental states of others (social cognition) is mediated by medial prefrontal cortex. Little is known about the anatomy of empathy and forgiveness. We used functional MRI to detect brain regions engaged by judging others' emotional states and the forgivability of their crimes. Ten volunteers read and made judgements based on social scenarios and a high level baseline task (social reasoning). Both empathic and forgivability judgements activated left superior frontal gyrus, orbitofrontal gyrus and precuneus. Empathic judgements also activated left anterior middle temporal and left inferior frontal gyri, while forgivability judgements activated posterior cingulate gyrus. Empathic and forgivability judgements activate specific regions of the human brain, which we propose contribute to social cohesion.

Functional anatomy of verbal fluency in people with schizophrenia and those at genetic risk. Focal dysfunction and distributed disconnectivity reappraised.

BACKGROUND: PET studies of verbal fluency in schizophrenia report a failure of 'deactivation' of left superior temporal gyrus (STG) in the presence of activation of left dorsolateral prefrontal cortex (DLPFC), which deficit has been attributed to underlying 'functional disconnectivity'. AIM: To test whether these findings provide trait-markers for schizophrenia. METHOD: We used H2(15)O PET to examine verbal fluency in 10 obligate carriers of the predisposition to schizophrenia, 10 stable patients and 10 normal controls. RESULTS: We found no evidence of a failure of left STG deactivation in carriers or patients. Instead, patients failed to deactivate the precuneus relative to other groups. We found no differences in functional connectivity between left DLPFC and left STG but patients exhibited significant disconnectivity between left DLPFC and anterior cingulate cortex. CONCLUSIONS: Failure of left STG 'deactivation' and left fronto-temporal disconnectivity are not consistent findings in schizophrenia; neither are they trait-markers for genetic risk. Prefrontal functional disconnectivity here may characterise the schizophrenic phenotype.

Discrete neurophysiological correlates in prefrontal cortex during hysterical and feigned disorder of movement.

The clinical distinction between hysterical symptoms and those that are feigned awaits objective validation. We used functional neuroimaging to examine the neural correlates of these two disorders.

No evidence for left superior temporal dysfunction in asymptomatic schizophrenia and bipolar disorder. PET study of verbal fluency.

BACKGROUND: Positron emission tomography (PET) studies have revealed functional left superior temporal gyrus (STG) abnormalities in symptomatic schizophrenia during word generation. AIMS: To discover if this dysfunction is present in asymptomatic schizophrenia. To determine whether, without concurrent symptomatology, schizophrenia and bipolar affective disorder (BPD) are distinguishable by differing regional cerebral blood flow (rCBF) patterns during word generation. METHOD: A PET verbal fluency protocol was applied to six patients with BPD in remission and six patients with asymptomatic schizophrenia. Analysis included 10 control subjects from a contemporaneous study. RESULTS: All groups showed relative reduction of rCBF in both superior temporal cortices. There were no quantitative differences in any group comparison. All groups exhibited negative covariation between rCBF in left prefrontal and right (but not left) temporal regions. CONCLUSIONS: Abnormal patterns of left STG function cannot be regarded as a trait marker for schizophrenia. Functional abnormalities may reflect aspects of mental state.

Hysterical paralyses as disorders of action.

Hysterical paralysis is an unusual diagnosis, requiring the physician to infer the intentional stance of the patient when the latter fails to act. This paper argues that the distinction between ''hysterical'' and ''feigned'' disorders cannot be currently justified on the basis of objective criteria. The physical ''signs'' of hysterical paralyses are those of voluntary motor inconsistency. The patient fails to perform certain acts, whereas others, utilising the same muscle groups, are preserved. Hence, hysterical paralyses are essentially disorders of action, themselves the product of abnormalities of mind, ''will'', or the intention to deceive (the ''self'' or the ''other''). The role of the psychodynamic unconscious in the maintenance of hysterical paralyses is problematic; their maintenance requires the patient's conscious attention: They remit with sedation and distraction. Although functional neuroimaging studies of these symptoms have been preliminary, they may eventually reveal an objective pathophysiology of the disordered ''will'', and a contrasting functional anatomy of the intentionally feigned symptom.

Prefrontal cortex activity in people with schizophrenia and control subjects. Evidence from positron emission tomography for remission of 'hypofrontality' with recovery from acute schizophrenia.

BACKGROUND: Hypo-activation of the left dorsolateral prefrontal cortex is inconsistently found in neuroimaging studies of schizophrenia. As the left dorsolateral prefrontal cortex is involved in the generation of action, disordered function in this region may be implicated in schizophrenic symptomatology. METHOD: We used H2 15O positron emission tomography to study dorsolateral prefrontal cortical function in men with schizophrenia (n = 13) and male control subjects (n = 6) performing joystick movements on two occasions, 4-6 weeks apart. The patients were initially in relapse. To clarify dorsolateral prefrontal cortical function we also scanned another group of control subjects (n = 5) performing mouth movements. RESULTS: The control subjects performing hand or mouth movements activated the left dorsolateral prefrontal cortex to a maximum when the movements were self-selected. The men with relapsed schizophrenia exhibited left dorsolateral prefrontal cortical hypoactivation, which remitted with symptomatic improvement. CONCLUSIONS: Hypofrontality in these patients is a dynamic phenomenon across time, possibly related to current symptomatology. The most appropriate question about the presence of hypofrontality in schizophrenia may be when, rather than whether, it will occur.

Rate of decline of chlorfluazuron concentration in the fat of cattle.

OBJECTIVE: To determine the rate of decline of chlorfluazuron (CFZ) concentration in the fat of cattle. DESIGN: A field depletion study. ANIMALS: Fifteen steers that had become contaminated with CFZ through eating cotton trash or cotton leaf pellets derived from CFZ-treated cotton crops. PROCEDURE: Fat samples were collected from the cattle at about 3 week intervals according to a schedule where each animal was sampled on four occasions up to 340 days after removal from the contaminated feed source. RESULTS: When the effects of dilution are removed CFZ concentrations were found to decline slowly for about 200 days. Depletion was minimal between 200 and 340 days. CONCLUSION: According to this trial, CFZ-contaminated, nonlactating cattle which have finished growing will remain contaminated. Field experience has not supported this conclusion.

Pathophysiology of 'positive' thought disorder in schizophrenia.

BACKGROUND: Formal thought disorder is a characteristic feature of psychosis, but little is known of its pathophysiology. We have investigated this in schizophrenia using positron emission tomography (PET). METHOD: Regional cerebral blood flow was measured using H2(15)O and PET while six people with schizophrenia were describing a series of 12 ambiguous pictures which elicited different degrees of thought-disordered speech. In a within-subject design, the severity of 'positive' thought disorder was correlated with cerebral blood flow across the 12 scans in each subject. RESULTS: Verbal disorganisation (positive thought disorder) was inversely correlated with activity in the inferior frontal, cingulate and left superior temporal cortex, and positively correlated with activity in the parahippocampal/anterior fusiform region bilaterally, and in the body of the right caudate (P < 0.001). The total amount of speech produced (independent of thought disorder) was positively correlated with activity in the left inferior frontal and left superior temporal cortex. CONCLUSIONS: The severity of positive thought disorder was inversely correlated with activity in areas implicated in the regulation and monitoring of speech production. Reduced activity in these regions may contribute to the articulation of the linguistic anomalies that characterise positive thought disorder. The positive correlations between positive thought disorder and parahippocampal/anterior fusiform activity may reflect this region's role in the processing of linguistic anomalies.

A PET study of voluntary movement in schizophrenic patients experiencing passivity phenomena (delusions of alien control).

Schizophrenic patients experiencing passivity phenomena believe their thoughts and actions to be those of external, or alien, entities. We wished to test the hypothesis that voluntary motor action in such patients would be associated with aberrant patterns of activation within the cerebral motor system. We used H2(15)O PET to study patients while they performed paced joystick movements on two occasions 4-6 weeks apart. During the first scan passivity symptoms were maximal, while by the second scan these symptoms had significantly improved in five of the seven patients. Two control groups were also scanned on two occasions: deluded schizophrenic patients without passivity phenomena and normal subjects. In normal subjects, performance of freely selected joystick movements with the right hand, compared with rest, revealed relative activation of prefrontal, premotor, motor and parietal cortical regions. Schizophrenic patients with passivity showed hyperactivation of parietal and cingulate cortices. This hyperactivation remitted in those subjects in whom passivity decreased over time. This reversible hyperactivity was not a feature of schizophrenics without passivity. Given that these hyperactive cerebral regions subserve attention to internal and external bodily space, and the attribution of significance to sensory information, they provide a plausible anatomical substrate for the misattribution of internally generated acts to external entities: the cardinal feature of delusions of passivity (alien control).