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J Atkinson

Publications and source records attributed to J Atkinson.

At least 19 recordsLinked to original sources
PubMed2006

The prevalence of suicidal behaviours in a group of HIV-positive men.

We studied a convenience sample of 54 HIV-positive men, recruited from HIV/AIDS community based service organizations. Data were collected on HIV risk factors and suicidal behaviours. Fifty-nine percent of the sample reported ever thinking about suicide, and 50% of those individuals reported attempting suicide at some point in their lives. Suicide ideation and attempts were more common among white participants. Suicidal behaviours were prevalent in this sample suggesting a need for mental health and suicide interventions targeted for this population.

Adult↗
PubMed2005

Recommendations for a technical quality control program for diagnostic X-ray equipment.

This position paper was produced by a working party set up by the Radiology Special Interest Group of the ACPSEM in 2001. It is designed to give the consensus view of College members in Australia and New Zealand on the nature and frequency of tests which should be performed on diagnostic x-ray equipment to maintain adequate quality control of imaging performance and radiation safety. Tests on mammographic equipment have been excluded having been covered in a previous ACPSEM position paper (Australas Phys Eng Sci Med, 24(3):107-131, 2001). Detailed descriptions of test procedures are not given but it is intended that a series of workbooks should be produced giving College recommended test methods for each imaging modality. The recommendations are produced here in an easy-to-read, tabular form giving the nature and purpose of each test and the implications of non-compliance with regard to image quality and radiation safety.

Australasia↗
PubMed2005

The prevalence of partner violence in a group of HIV-infected men.

There is a paucity of literature regarding partner violence among males that identifies the sex and relationship of their partner(s). We studied a convenience sample of 54 HIV-infected men, recruited from HIV/AIDS service organizations. Using a standard questionnaire, we collected data on HIV risk behaviours and self-reports of acts of partner violence and forced sex. Physical violence perpetrated by a primary or a casual partner was reported by 39% and 17% of the sample, respectively. Life-time forced sex by a primary or casual partner was reported by 32% and 15% of the sample, respectively. Forced sex was more commonly reported by participants who were non-white and reported a higher number of primary partners in the previous 12 months. We recommend that health care providers be aware of the high rates of intimate partner violence among men infected or at risk of infection with HIV.

Adolescent↗
PubMed2005

Asymmetric deterioration of spatial awareness with diminishing levels of alertness in normal children and children with ADHD.

BACKGROUND: There is growing literature suggesting that some children diagnosed with attention deficit hyperactivity disorder (ADHD) can show a significant bias in attention away from left space. Here we examine mechanisms that may underpin these effects in both clinical and non-clinical child populations. Unilateral spatial inattention (unilateral neglect) is a commonly reported consequence of stroke in adults. Although for most patients the problem is relatively transient, persistent forms of neglect are almost exclusively associated with right hemisphere lesions. It has been suggested that this chronicity may result from co-existing disruption to right hemisphere dominant systems that mediate alertness. Here we present two studies examining the relationship between sustained attention and left spatial awareness in childhood. METHOD: In the first, normal children without the ADHD diagnosis were administered a non-spatial test of sustained attention/alertness. Children who performed poorly at this task, relative to their more attentive peers, showed a modest but reliable delay in awareness of left-sided visual information. Furthermore, attention towards the left declined for both groups as a function of time-on-task, suggesting a significant within-subject modulatory effect of alertness on spatial awareness. The second study examines this relationship in children referred to clinical services for attention problems. Irrespective of their final diagnosis, children were divided into two groups according to their performance in sustained attention/alertness tasks. RESULTS: The results suggest that, regardless of the children's clinical diagnosis, diminished sustained attention/alertness levels formed the strongest predictor of relatively delayed awareness of information presented within left visual space. Two children within this group exhibited signs of hitherto undetected spatial neglect as severe as that observed in some brain-injured adults. CONCLUSIONS: Clinical and theoretical implications are discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Non-cycloplegic refractive screening can identify infants whose visual outcome at 4 years is improved by spectacle correction.

The Second Cambridge Population Infant Vision Screening Programme using the VPR-1 videorefractor without cycloplegia was undertaken in order to identify those infants with refractive errors who were potentially amblyogenic or strabismogenic. Infants identified at eight months were entered into a control trial of treatment with partial spectacle correction and underwent a long-term follow-up that monitored a wide range of visual, visuoperceptual, visuocognitive, visuomotor, linguistic and social development. In the present paper, the authors report on the outcome measures of visual acuity and strabismus. Poor acuity was defined as a best-corrected acuity of 6/12 or worse on crowded letters or 6/9 or worse on single letters, at age 4 years. Acuity was measured in 79 infants who were significantly hyperopic and/or anisometropic at 11-12 months of age, 23 who showed hyperopia of +3D but less than +3.5D, 196 control subjects, 14 controls with refractive errors, and 126 others who showed an accommodative lag on screening but were not significantly hyperopic on first retinoscopy. There was a poorer acuity outcome in the untreated group of hyperopes compared to controls (p < 0.0001) and to the children who were compliant in spectacle wear (p < 0.001) or who were prescribed spectacles (p < 0.05). Children who were significantly hyperopic at eight months were also more likely to be strabismic by 5.5 years compared to the emmetropic control group (p < 0.001). However, the present study did not find a significant difference in the incidence of strabismus between corrected and uncorrected hyperopic infants. Children who were not refractively corrected for significant hyperopia were four times more likely to have poor acuity at 5.5 years than infants who wore their hyperopic correction, supporting the findings of the First Cambridge Population Infant Vision Screening Programme.

Accommodation, Ocular↗
PubMed2004

Visual function at school age in children with neonatal encephalopathy and low Apgar scores.

OBJECTIVE: To assess different aspects of visual function at school age in children who suffered from neonatal encephalopathy. METHOD: Thirty nine full term infants with neonatal encephalopathy, low Apgar scores, and early neonatal imaging were studied using a battery of tests assessing different aspects of visual function (crowding acuity, stereopsis, visual fields) at school age. The results were compared with brain magnetic resonance imaging (MRI) findings and, when possible, with the results of the assessment of visual function performed at 5 and 12 months, available in 24 of the 39 children examined at school age. RESULTS: Sixteen of the 39 children (41%) had abnormal results at school age in at least one of the visual tests used. Seven of these 16 were untestable on all tests. The remaining 23 children (59%) had normal results. CONCLUSIONS: The presence and severity of visual impairment was related to the severity of brain lesions. Moderate or severe basal ganglia lesions and severe white matter changes were always associated with abnormal visual function. Infants with normal MRI, minimal basal ganglia lesions, and minimal or moderate white matter involvement tended to have normal vision. It was also found that the assessment of visual function performed in the first year was a reliable indicator of visual function at school age. With two exceptions, the results on the 5 month visual assessment were predictive of visual outcome at school age. In the remaining two cases, a normal visual outcome at 5 years was associated with visual abnormalities at 5 months but these had already normalised by the age of 1 year.

Apgar Score↗
PubMed2004

Structure-function relationship in the tocopherol transfer protein.

The role of specific amino acid residues in mediating the biochemical functions of tocopherol transfer protein (TTP) was investigated using site-directed mutagenesis and functional assays. These findings further current understanding of TTP mechanism of action and its role in human health.

Carrier Proteins↗
PubMed2003

The effect of vitamin E on the structure of membrane lipid assemblies.

The effects of vitamin E on the activity of membrane-dependent enzymes suggest that it acts indirectly by modifying some properties of the lipid host. The effects of alpha-tocopherol (alpha-T) and alpha-tocopherol hemisuccinate (alpha-THS) on phospholipid monolayer structure, curvature, and bending elasticity were examined using X-ray diffraction and the osmotic stress method. These ligands were mixed with the hexagonal phase-forming lipid, dioleoylphosphatidylethanolamine (DOPE). Increasing levels up to 50 mol% alpha-T in DOPE in excess water result in a systematic decrease in the lattice dimension. Analysis of the structural changes imposed by alpha-T shows that it contributes a spontaneous radius of curvature of -13.7 A. This unusually negative value is comparable to diacylglycerols. alpha-T does not affect the bending elasticity of these monolayers. alpha-THS in its charged form decreases membrane curvature, but in its undissociated neutral form has a qualitatively similar but reduced effect on monolayer curvature, as does alpha-T. We discuss these results in terms of the local stresses such ligands would produce in the vicinity of a membrane protein, and how one might expect proteins to respond to such stress.

Cell Membrane↗
PubMed2003

Therapeutic perspectives for melatonin agonists and antagonists.

Melatonin is a neurohormone synthesized in the pineal gland during the dark period in all species, including humans. The diversity and differences in melatonin receptor distribution in the brain and extracerebral organs suggest multiple functional roles for melatonin. Administration of melatonin agonists reduces neophobia and treatment with a melatonin antagonist during the dark period reverses the anxiolytic-like effect of endogenous melatonin. Chronic treatment with agonists prevents various perturbations induced by chronic mild stress. Melatonin in vivo directly constricts cerebral arterioles in rats and decreases the lower limit of cerebral blood flow autoregulation, suggesting that melatonin may diminish the risk of hypoperfusion-induced cerebral ischemia. At the extracerebral level, melatonin regulates intestinal motility in rats. The intestinal postprandial motor response is shorter in the dark phase than in the light phase and this reduction is reversed in animals pretreated with a melatonin antagonist. Moreover, melatonin reduces the duration of cholecystokinin excitomotor effect. Endogenous melatonin may modulate intestinal motility to coordinate intestinal functions such as digestion and transit and control the metabolism of the animal. An adipocyte melatonin binding site may also participate in this control. Melatonin is involved in a wide range of physiological functions. The question remains as to whether evolution, adaptation and diurnal life have modified the physiological role of melatonin in humans. Moreover, the functional role of each of the receptor subtypes has to be characterized to design selective ligands to treat specific diseases.

Animals↗
PubMed2003

Neonatal cerebral infarction and visual function at school age.

OBJECTIVE: To assess various aspects of visual function at school age in children with neonatal cerebral infarction. PATIENTS AND METHODS: Sixteen children born at term, who had cerebral infarction of perinatal onset on neonatal magnetic resonance imaging (MRI) were assessed using a battery of visual tests. This included measures of crowding acuity (Cambridge Crowding Cards), stereopsis (TNO test), and visual fields. The results of the visual assessment were compared with the type and the extent of the lesion observed on neonatal MRI. RESULTS: Only six of the 16 children (28%) had some abnormalities of visual function on these tests. Visual abnormalities were more common in children with more extensive lesions involving the main branch of the middle cerebral artery and were less often associated with lesions in the territory of one of the cortical branches of the middle cerebral artery. The presence of visual abnormalities was not always associated with the involvement of optic radiations or occipital primary visual cortex. Abnormal visual fields were only found in children who also developed hemiplegia. CONCLUSIONS: Abnormality of visual function is not common in children who had neonatal infarction and, when present, tends to be associated with hemiplegia and more extensive lesions.

Cerebral Infarction↗
PubMed2003

No association of income inequality with adult mortality within New Zealand: a multi-level study of 1.4 million 25-64 year olds.

STUDY OBJECTIVE: To determine the association of regional income inequality within New Zealand with mortality among 25-64 year olds. DESIGN: Individual census and mortality records were linked over the 1991-94 period. Income inequality (Gini coefficients) and average household income variables were calculated for 35 regions. "Individual level" variables were sex, age, ethnicity, household income, rurality, and small area socioeconomic deprivation. Logistic regression was used for the analyses. Sensitivity analyses for the level of regional aggregation were conducted. PARTICIPANTS: 1.4 million New Zealand census respondents aged 25-64 years followed up for mortality for three years. MAIN RESULTS: Controlling for age, ethnicity, rurality, household income, and regional mean income, there was no association of income inequality with all cause mortality for either men (OR=1.007 for a 0.01 increase in the Gini, 95% confidence intervals 0.989 to 1.024) or women (OR=1.004, 0. 983 to 1.026). By cause of death (cancer, cardiovascular disease, unintentional injury, and suicide) there was some suggestion of a positive association for female unintentional injury (OR=1.068, 0.952 to 1.198) and suicide (OR=1.087, 0.957 to 1.234) but the 95% confidence intervals all included 1.0. Failure to control for ethnicity at the individual level resulted in some association of increasing regional income inequality with increasing mortality risk. Using fewer (n=14) or more (n=73) regional divisions did not substantially change the findings. CONCLUSION: There is no convincing evidence of an association of income inequality within New Zealand with adult mortality. Previous ecological analyses within New Zealand suggesting an association of income inequality with mortality were confounded by ethnicity at the individual level. However, this study does not refute the possibility that income inequality at the national level affects health.

Adult↗
PubMed2003

Unemployment and suicide. Evidence for a causal association?

OBJECTIVES: To determine the independent associations of labour force status and socioeconomic position with death by suicide. DESIGN: Cohort study assembled by anonymous and probabilistic record linkage of census and mortality records. PARTICIPANTS: 2.04 million respondents to the New Zealand 1991 census aged 18-64 years. MAIN OUTCOME MEASURE: Suicide in the three years after census night. RESULTS: The age adjusted odds ratios (95% confidence intervals) of death by suicide among 25 to 64 year olds who were unemployed compared with employed were 2.46 (1.10 to 5.49) for women and 2.63 (1.87 to 3.70) for men. Similarly increased odds ratios were observed for the non-active labour force compared with the employed. Strong age only adjusted associations of suicide death with the socioeconomic factors of education (men only), car access, and household income were observed. Compared with those who were married on census night, the non-married had odds ratios of suicide of 1.81 (1.22 to 2.69) for women and 2.08 (1.66 to 2.61) for men. In a multivariable model the association of socioeconomic factors with suicide reduced to the null. However, marital status and labour force status remained strong predictors of suicide death. Unemployment was also strongly associated with suicide death among 18-24 year old men. Sensitivity analyses suggested that confounding by mental illness might explain about half, but not all, of the association between unemployment and suicide. CONCLUSIONS: Being unemployed was associated with a twofold to threefold increased relative risk of death by suicide, compared with being employed. About half of this association might be attributable to confounding by mental illness.

Adolescent↗
PubMed2002

Influence of the relA gene on ribosome frameshifting.

We have examined the influence of genotype at the relA locus on the kinetics of leftward (or -1) frameshifting at a variety of codons calling for a limiting aminoacyl-tRNA species. We used lacZ left-frameshift reporter constructs carrying the sequenceU UUC XYZ, whereXYZ was each of three triplets coding for three different amino acids; we slowed the ribosomes at each of these by limiting for the amino acid or for the aminoacyl-tRNA. In all cases, limitation stimulated leftward frameshifting. In all cases, the stimulation was greater in relA mutant cells than in their wild-type relA(+) counterparts. In the latter genotype, the increased frameshifting was constant from the start of the limitation regime. This was also true of the relA mutant strain during limitation for lysine-tRNA or for leucine; however, during limitation for isoleucine-tRNA (or for isoleucine) the mutant showed a gradual, progressive increase in frameshifting, suggesting an indirect effect. We suggest that gradual accumulation of undermodified tRNAs, which is characteristic of the relA response, is involved. However, the specific modification involved is unknown. It is not queosine: analysis of a tgt mutant that is completely defective in queosine modification showed no increase in leftward frameshifting on the reporter which showed the larger, gradual increase during the relA response to isoleucine-tRNA limitation.

Escherichia coli↗
PubMed2002

Visual function and EEG reactivity in infants with perinatal brain lesions at 1 year.

The aim of this study was to examine the correlation between EEG, visual, and brain MRI findings in 19 term infants with perinatal brain lesions. All 19 had their visual acuity and visual fields assessed and had an EEG and a brain MRI performed at 1 year of age. Four of the five infants with normal optic radiations and occipital cortices on MRI had normal vision. Involvement of optic radiations and occipital cortices was only associated with visual abnormalities in eight of 14 infants. The correlation between visual abnormalities and EEG findings was stronger. All infants with a completely normal EEG from the posterior regions had normal vision and all those with an EEG non-reactive to eye closure had visual abnormalities, irrespective of MRI data. A reactive EEG with other abnormal features (such as spikes, rapid or slow activities) was accompanied by abnormal vision in five of eight participants. Results suggest that there is a better correlation between visual function and EEG activity than between visual function and involvement of the classical visual areas of the occipital cortex and optic radiations on brain MRI at 1 year of age.

Action Potentials↗
PubMed2002

Withdrawal reveals lack of effect of prolonged antihypertensive treatment on intrinsic aortic wall stiffness in senescent spontaneously hypertensive rats.

1. Chronic antihypertensive treatment lowers cardiovascular morbidity and mortality. The beneficial effect on the blood vessel wall may be due to the lowering of blood pressure (BP) and, hence, wall stress (WS), or to a treatment-induced change in wall structure. 2. We have previously shown that, when evaluated at the same level of BP and WS, the stiffness of the aortic wall of old spontaneously hypertensive rats (SHR) is higher than that of young and adult SHR and that of age-matched Wistar-Kyoto (WKY) rats. In the present study, we tested the hypothesis that the intrinsic changes in wall composition and mechanics in old SHR can be modulated by long-term treatment with an angiotensin I-converting enzyme inhibitor (captopril; 40 mg/kg per day) combined with a diuretic (hydrochlorothiazide; 20 mg/kg per day) and that treatment withdrawal would reveal whether such changes are maintained when BP and WS return to pretreatment levels. 3. We evaluated aortic structure and mechanics in SHR following 1 week withdrawal of oral antihypertensive treatment from 3 to 15 months of age (n = 8). Results were compared with age-matched SHR that were maintained on treatment (n = 12) or were not treated (n = 13) and with WKY rats (no treatment n = 11; maintained n = 11; withdrawn n = 10). 4. Isobaric aortic wall stiffness was estimated from the ratio of baseline aortic pulse wave velocity (PWV) to BP and the slope relating aortic PWV to BP following sodium nitroprusside-induced hypotension. Relative wall stiffening was estimated as the ratio of elastic modulus (EM) to WS. We argued that if treatment produced a change in wall elastin or collagen content, with a subsequent decrease in isobaric wall stiffness, then this would be maintained when BP increased following withdrawal of treatment. 5. In old SHR, treatment lowered isobaric wall stiffness (baseline PWV/BP 4.6 +/- 0.3 cm/s per mmHg; slope relating PWV to BP 6.7 +/- 0.4 x 10-3 cm/s per mmHg and EM/WS 4.1 +/- 0.4 vs 6.1 +/- 0.4 cm/s per mmHg, 9.7 +/- 0.9 x 10-3 cm/s per mmHg and 8.9 +/- 1.1, respectively, without treatment; all P < 0.05). After 1 weeks treatment withdrawal, the indices (5.7 +/- 0.2 cm/s per mmHg, 9.1 +/- 0.2 x 10-3 cm/s per mmHg and 7.2 +/- 0.6) increased in parallel with the increase in WS to levels similar to those observed in untreated SHR. There were no significant differences among the WKY rat groups. 6. Treatment increased the elastin and collagen contents of the aortic wall in both SHR (196 +/- 13 and 128 +/- 5 vs 111 +/- 9 and 86 +/- 4 mg/g wet weight, respectively, in untreated; P < 0.05) and WKY rats (190 +/- 19 and 135 +/- 4 vs 115 +/- 7 and 114 +/- 5 mg/g wet weight, respectively, in untreated; P < 0.05). This increase remained following withdrawal (213 +/- 26 and 118 +/- 4 vs 161 +/- 14 and 127 +/- 4 mg/g wet weight in SHR and WKY rats, respectively). 7. In summary, 1 year of treatment with captopril plus hydrochlorothiazide increases wall elastin content and reduces WS and stiffness in old SHR. Following withdrawal, elastin content remains high, but wall stiffness parallels WS in a manner similar to that in untreated SHR.

Aging↗
PubMed2002

A test battery of child development for examining functional vision (ABCDEFV).

A battery of 22 tests is described, intended to give an integrated assessment of children's functional visual capacities between birth and four years of age. As well as sensory visual measures such as acuity, visual fields and stereopsis, the battery is intended to tap a range of perceptual, motor, spatial and cognitive aspects of visual function. Tests have been drawn from practice in ophthalmology and orthoptics, vision research, paediatric neurology, and developmental psychology to give an overall view of children's visual competences for guidance in diagnosis, further investigation, management and rehabilitation of children with developmental disorders. 'Core vision tests' require no motoric capacities beyond saccadic eye movements or linguistic skills and so assess basic visual capacities in children of any age. 'Additional tests' have age-specific requirements and are designed to pinpoint specific deficits in the perceptual, visuo-motor and spatio-cognitive domains. Normative data are reported on nine age groups between 0-6 weeks and 31-36 months, each including 32-43 typically developing children. Pass/fail criteria for each test are defined. These data allow the selection of a subset of tests for each age group which are passed by at least 85% of normally developing children, and so are appropriate for defining normal development. The normalized battery has been applied to a range of at-risk and clinical groups. Aspects of children's visual performance are discussed in relation to neurobiological models of visual development.

Child Development↗
PubMed2002

Cortical visual evoked potentials in very low birthweight premature infants.

OBJECTIVES: To compare the age of onset of the pattern orientation reversal visual evoked potential (OR-VEP) in a group of very low birthweight (VLBW) premature infants with term infants matched for postconceptual age at testing. The OR-VEP measure is used as an indicator of visual cortical functioning because of the specificity of cortical neurones in showing sensitivity to changes of slant or orientation. DESIGN: Results are given for 24 VLBW infants, born at 24-32 weeks gestation weighing less than 1500 g, and 31 infants born at term. The steady state evoked potential to a grating pattern reversing in orientation (between 45 degrees and 135 degrees) at 4 reversals/second and 8 reversals/second was recorded. RESULTS: The VLBW infants with normal neonatal ultrasound results (and normal neurological outcome at 3 years of age) showed a significant OR-VEP with a similar postnatal time course to the term infants. Four premature infants, showing appreciable abnormalities on ultrasound examination, did not show normal onset of the OR-VEP, and all had an abnormal neurological outcome. CONCLUSIONS: This result can be taken to indicate that the onset of cortical function is similar in healthy preterm infants to term infants. The visual development of the premature infants was neither accelerated nor delayed as a result of their extra visual experience. The OR-VEP can be used as a prognostic indicator of early brain development alongside other neurological measures. It may also be a very early indicator of later neurological outcome.

Aging↗