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Biomedical subjects

A Whitaker

Publications and source records attributed to A Whitaker.

At least 19 recordsLinked to original sources
PubMed2003

Climbing-specific finger endurance: a comparative study of intermediate rock climbers, rowers and aerobically trained individuals.

The aim of this study was to compare the climbing-specific finger endurance of climbers, rowers and aerobically leg trained athletes. Twenty-seven males aged 21.2 +/- 2.2 years (mean +/- s) volunteered for the study. The participants were intermediate rock climbers (n = 9), rowers (n = 9) and leg trained athletes (n = 9). Maximal voluntary contraction (MVC) was determined on climbing-specific finger apparatus. Endurance isometric exercise was performed at 40% MVC in three tests performed in a random order: (1) sustained exercise; (2) 6 s exercise, 4 s rest; and (3) 18 s exercise, 12 s rest. Pre- and post-exercise blood pressure and blood lactate concentration, together with post-exercise pain perception, were measured. The climbers had a significantly greater MVC (383 +/- 35.6 N) than the rowers (321 +/- 49.5 N, P = 0.007) and aerobically leg trained athletes (288 +/- 60.6 N, P = 0.001). There were no significant differences between the groups in terms of endurance times for any of the tests. In the test with 18 s exercise and 12 s rest, the climbers showed a significantly higher increase in blood lactate concentration, on average, than the rowers by 0.01-0.89 mmol x l(-1) (P = 0.006); there were no significant differences, on average, in the comparisons of climbers and the leg trained athletes and rowers and the leg trained athletes. There were no significant differences in the average changes in blood pressure from rest to post-exercise between any of the groups. Although the climbers had greater MVC on average than the other two groups, there were no significant differences in average endurance times amongthe groups. These findings suggest that training for rock climbing and participation in rock climbing may result in some specific adaptations. However, we acknowledge that this study is descriptive and there is the possibility that differences between groups could be attributed to self-selection.

Adolescent↗
PubMed2001

Behavioural problems in children who weigh 1000 g or less at birth in four countries.

BACKGROUND: The increased survival chances of extremely low-birthweight (ELBW) infants (weighing <1000 g at birth) has led to concern about their behavioural outcome in childhood. In reports from several countries with different assessments at various ages, investigators have noted a higher frequency of behavioural problems in such infants, but cross-cultural comparisons are lacking. Our aim was to compare behavioural problems in ELBW children of similar ages from four countries. METHODS: We prospectively studied 408 ELBW children aged 8-10 years, whose parents completed the child behaviour checklist. The children came from the Netherlands, Germany, Canada, and USA. The checklist provides a total problem score consisting of eight narrow-band scales. Of these, two (aggressive and delinquent behaviour) give a broad-band externalising score, three (anxious, somatic, and withdrawn behaviour) give a broad-band internalising score, and three (social, thought, and attention problems) indicate difficulties fitting neither broad-band dimension. For each cohort we analysed scores in ELBW children and those in normal- birthweight controls (two cohorts) or national normative controls (two cohorts). Across countries, we assessed deviations of the ELBW children from normative or control groups. FINDINGS: ELBW children had higher total problem scores than normative or control children, but this increase was only significant in European countries. Narrow-band scores were raised only for the social, thought, and attention difficulty scales, which were 0.5-1.2 SD higher in ELBW children than in others. Except for the increase in internalising scores recorded for one cohort, ELBW children did not differ from normative or control children on internalising or externalising scales. INTERPRETATION: Despite cultural differences, types of behavioural problems seen in ELBW children were very similar in the four countries. This finding suggests that biological mechanisms contribute to behavioural problems of ELBW children.

Canada↗
PubMed2000

Binocular summation in the fovea and peripheral field of anisometropic amblyopes.

PURPOSE: Binocular performance in the central and peripheral visual fields was compared for normal and anisometropic amblyopes. METHODS: Binocular and monocular thresholds to a light detection task were measured along the four principal meridia in 10 young normal subjects and 10 anisometropic amblyopes using the Humphrey's Visual Field Analyser. Thresholds were obtained at the fovea and at retinal eccentricities of 5 masculine, 10 masculine, 15 masculine, 25 masculine, 40 masculine and 55 masculine on the horizontal, vertical and oblique meridia of 45 masculine and 135 masculine. RESULTS: Binocular summation ratios (binocular sensitivity/ 'best' monocular sensitivity) were calculated for all the eccentricities. In the normal group, the mean binocular summation ratio for the fovea and the peripheral field was not significantly different. In the amblyopic group, subjects showed no or minimal binocular summation in the foveal region but reached normal ratios in the periphery. DISCUSSION: Results are discussed in terms of tolerance to interocular sensitivity differences in the periphery and selective losses in cortical cells.

Adolescent↗
PubMed1998

Randomised trial of effectiveness of second eye cataract surgery.

BACKGROUND: The effectiveness of cataract surgery on one eye is well established, but concerns over health-care expenditure have called into question the value of cataract surgery on the second eye. We examined the effects of second eye surgery in terms of patient perceptions as well as through visual acuity, contrast sensitivity, and stereoacuity tests. METHODS: 208 otherwise healthy patients awaiting second eye cataract surgery were recruited into our randomised trial. At randomisation participants were allocated expedited surgery (planned to take place within 6 weeks) or routine surgery (routine waiting time, 7-12 months). Assessments were made at randomisation and again at review after about 6 months. Eight primary trial outcomes consisted of four questionnaire items and four visual function tests, done with both eyes open. FINDINGS: Traditional clinical tests of success in cataract surgery (visual acuity and contrast sensitivity) showed only slight differences in binocular vision in favour of the expedited-surgery group. There were major benefits for the expedited-surgery group in terms of reported visual symptoms and effects on quality of life. At review, differences in self-reported vision related difficulties between the two groups ranged from 11% (95% CI 4.4-17%, activities) to 30% (19-41%, reading). Stereoacuity was better in the expedited surgery group, the difference between the groups for the proportions with stereoacuity of 3000 s of arc or worse was 58% (47-69%). INTERPRETATION: This trial has shown that there is a clear benefit from second eye cataract surgery.

Adult↗
PubMed1996

Comorbidity and boundaries of affective disorders with anxiety disorders and substance misuse: results of an international task force.

Associations between affective disorders, anxiety disorders, and substance use disorders were examined in epidemiological studies conducted in Germany, Switzerland, Puerto Rico, and the mainland US. There was a remarkable degree of similarity across studies in the magnitude and type of specific disorders associated with the affective disorders. Comorbidity with affective disorders was greater for the anxiety disorders than for substance misuse. Panic disorder was the subtype of anxiety that was most highly comorbid with depression. Social phobia was the specific phobic type with the strongest association with the affective disorders. The magnitude of associations between substance misuse and affective disorders generally was quite low and less consistent across sites. No major differences were found in the patterns of comorbidity by gender or age group, affective subtype or prevalence period. The onset of anxiety disorders generally preceded that of depression, whereas alcohol misuse was equally likely to pre-or post-date the onset of affective disorders. Finally, comorbidity was associated with an elevation in treatment rates across all sites, confirming Berkson's paradox on an international level.

Adolescent↗
PubMed1994

Diagnostic criteria for migraine. A validity study.

To identify the optimum combination of symptoms for the International Headache Society (IHS) diagnostic criteria for migraine, the criteria were systematically assessed for validity using an epidemiologic sample from Zurich, Switzerland. The indicators of validity used included subjective distress, occupational impairment, family history of migraine, and treatment. The symptoms that provided the best discrimination between migraine and other headache subtypes were photophobia, phonophobia, and osmophobia, in combination with gastrointestinal symptoms. The evaluation of the validity of the IHS classification of migraine is impeded by several factors, including: the presence of multiple headache syndromes within an individual, the tendency for headache characteristics to change over a lifetime, the effects of headache treatments in obscuring syndromes, and the lack of generalizability of findings based on clinical samples. The methods used in this study serve as a model for applying statistical techniques for evaluating the validity of diagnostic criteria. The findings, however, should be replicated in additional studies to determine their generalizability to specific demographic and clinical subgroups.

Adult↗
PubMed1993

An emerging schizophrenic syndrome.

This case history describes a 16-year-old adolescent male who developed schizophrenia with prominent negative symptoms. For the previous 6 years his diagnosis had been oppositional defiant disorder or conduct disorder. The clinical presentation, differential diagnosis, and management are discussed. The case exemplifies issues addressed in DSM IV.

Adolescent↗
PubMed1992

Neuroleptics in pediatric psychiatry.

At the present time, neuroleptics are indicated for the treatment of acute psychotic states as well as Tourette's syndrome in children and adults. Neuroleptics may have a useful role in the attenuation of problem behaviors, such as stereotypies, hyperactivity, self-injury, and aggressive outbursts in infantile autism, pervasive developmental disorder NOS, and mental retardation, but they do not improve the underlying condition. Neuroleptics are not the agents of first choice for treatment of hyperactivity or aggression in children who do not have major developmental handicaps. Common and troublesome side effects associated with neuroleptic use in children and adolescents include sedation, extrapyramidal symptoms, and withdrawal dyskinesias; therefore, close monitoring is required. Neuroleptics should be used cautiously and only as an adjunct to other nonpharmacologic interventions.

Adolescent↗
PubMed1990

Uncommon troubles in young people: prevalence estimates of selected psychiatric disorders in a nonreferred adolescent population.

A two-stage epidemiologic strategy was used to estimate the lifetime prevalence of selected DSM-III-defined psychiatric disorders in a county-wide secondary school population (N = 5596). Screening tests used in the first stage included items based on DSM-III criteria for eating disorders and panic disorder, as well as the Leyton Obsessional Inventory-Child Version and the Beck Depression Inventory. Based on interviews (n = 356) by clinicians in the second stage, the lifetime prevalence of anorexia nervosa was 0.2%; bulimia, 2.5%; panic disorder, 0.6%; obsessive-compulsive disorder, 1.9%; major depression, 4.0%; dysthymic disorder, 4.9%; and generalized anxiety disorder, 3.7%. While rates of mental health service utilization varied greatly by diagnosis, only 41% of students who were assigned both a diagnosis and a rating of impairment had received any kind of clinical attention.

Adolescent↗
PubMed1990

Neonatal cranial ultrasound abnormalities: association with developmental delay at age one in low birth weight infants.

Relationships between abnormalities on neonatal serial cranial ultrasound and cognitive development at age one year were examined in 153 low birth weight (LBW) infants. Infants with complex injury (persistent parenchymal echogenicity, lucency, or persistent ventricular enlargement) scored significantly lower on the Bayley Mental Development Index than noninjured infants. Nine of 11 infants with complex injury had severe developmental delay in contrast to 3/110 of the noninjured. Adjusting for birth weight, gestational age, head circumference and social class, infants with complex injury were 33 times more likely to be severely delayed than noninjured infants. Risk for severe delay associated with LBW appeared to be indirect, through increased probability of ultrasonographic abnormality. The poorest developmental outcome was seen in infants with both complex perinatal brain injury and either very LBW or very young gestational age. However, very LBW infants with normal neonatal ultrasounds were at negligible risk for severe delay at age one.

Birth Injuries↗
PubMed1989

The struggle to be thin: a survey of anorexic and bulimic symptoms in a non-referred adolescent population.

Ninety-one per cent of a county-wide high school population (N = 5596) completed the Eating Symptoms Inventory (ESI) and the Eating Attitudes Test (EAT). Being female, older and heavier are far more strongly associated with anorexic and bulimic symptoms than is social class. ESI approximations of the DSM-III criteria for anorexia nervosa or bulimia suggest that while both conditions are rare (less than 1%), bulimia is the more prevalent disorder.

Adolescent↗
PubMed1989

Childhood obsessive compulsive disorder: a two-year prospective follow-up of a community sample.

A 2-year prospective follow-up of a community-based sample of adolescents previously diagnosed as having obsessive compulsive disorder (OCD) or "obsessive compulsive spectrum" disorder and a control sample was completed by clinicians experienced with OCD but blind to prior diagnosis. An initial diagnosis of OCD or "other psychiatric disorder with OC features" was most likely to predict a diagnosis of OCD at follow-up. Subclinical OCD at baseline did not strongly predict continuing psychopathology. A prior diagnosis of obsessive-compulsive personality predicted continued obsessive-compulsive symptoms but its relationship to OCD remains obscure.

Adolescent↗
PubMed1989

Growth rate in adolescents with obsessive-compulsive disorder.

In an epidemiological study of 5,596 high school students, the authors identified 20 adolescents with obsessive-compulsive disorder and compared their physical size to that of adolescents of the same sex with no obsessive-compulsive symptoms. The obsessive-compulsive boys (N = 11) were shorter and weighed less than the other boys (N = 2,479) and were shorter than a subsample of normal boys (N = 33) and boys with other psychiatric diagnoses (N = 16). Regression analysis showed a flatter growth pattern through adolescence for the obsessive-compulsive boys (although within the 95% confidence limits for the other boys), suggesting a subtle neuroendocrine dysfunction in obsessive-compulsive disorder.

Adolescent↗