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Biomedical subjects

D W Evans

Publications and source records attributed to D W Evans.

At least 19 recordsLinked to original sources
PubMed2006

Repetitive and ritualistic behaviour in children with Prader-Willi syndrome and children with autism.

BACKGROUND: Recent research has shown that the range of repetitive behaviour seen in individuals with Prader-Willi syndrome (PWS) extends beyond food-related behaviour. METHODS: The presence and intensity of repetitive, rigid and routinized behaviour in children with PWS was compared with that seen in children with another neurodevelopmental condition in which repetitive behaviour is common: children with autism. Parents completed the Childhood Routines Inventory (CRI). RESULTS: Contrary to our predictions, controlling for developmental level, children with PWS and children with autism showed similar levels of repetitive and ritualistic behaviour overall and on the two CRI factors measuring 'just right' and 'repetitive' behaviour. Indeed, the majority of the sample of parents of children with PWS endorsed most items on the CRI. However there was some specificity at the level of individual items with parents of children with PWS more frequently endorsing an item on 'collecting and storing objects' and parents of children with autism more frequently endorsing 'lining up objects', 'has a strong preference for certain foods' and 'seems aware of detail at home'. CONCLUSIONS: These findings confirm the range of repetitive behaviours that form part of the behavioural phenotype of PWS, including insistence on sameness and 'just right' behaviours, and uncover a surprising overlap with those seen in children with autism. Clinical management for children with PWS should include advice and education regarding management of repetitive and rigid behaviour. Future research should investigate whether the repetitive behaviours that form part of the behavioural phenotype of both PWS and autism are associated with a common neuropsychological, neurotransmitter or genetic origin.

Adolescent↗
PubMed2005

Does it matter that organ donors are not dead? Ethical and policy implications.

The "standard position" on organ donation is that the donor must be dead in order for vital organs to be removed, a position with which we agree. Recently, Robert Truog and Walter Robinson have argued that (1) brain death is not death, and (2) even though "brain dead" patients are not dead, it is morally acceptable to remove vital organs from those patients. We accept and defend their claim that brain death is not death, and we argue against both the US "whole brain" criterion and the UK "brain stem" criterion. Then we answer their arguments in favour of removing vital organs from "brain dead" and other classes of comatose patients. We dispute their claim that the removal of vital organs is morally equivalent to "letting nature take its course", arguing that, unlike "allowing to die", it is the removal of vital organs that kills the patient, not his or her disease or injury. Then, we argue that removing vital organs from living patients is immoral and contrary to the nature of medical practice. Finally, we offer practical suggestions for changing public policy on organ transplantation.

Brain Death↗
PubMed2003

Contrast sensitivity improves after brimonidine therapy in primary open angle glaucoma: a case for neuroprotection.

AIMS: To determine the visual outcome following initiation of brimonidine therapy in glaucoma. METHODS: 16 newly diagnosed previously untreated glaucoma patients were randomly assigned to either timolol 0.5% or brimonidine 0.2%. Visual acuity, contrast sensitivity (CS), visual fields, intraocular pressure (IOP), blood pressure, and heart rate were evaluated at baseline and after 3 months. RESULTS: IOP reduction was similar for both groups (p<0.05). Brimonidine improved CS; in the right eye at 6 and 12 cpd (p=0.043, p=0.017); in the left eye at 3 and 12 cpd (p=0.044, p=0.046). Timolol reduced CS at 18 cpd in the right eye (p=0.041). There was no change in any other measured parameters. CONCLUSION: Glaucoma patients exhibit improved CS on initiation of brimonidine therapy.

Adrenergic alpha-Agonists↗
PubMed2001

Ego development, self-perception, and self-complexity in adolescence: a study of female psychiatric inpatients.

A study of two groups of female psychiatric inpatients, differing in level of ego development, explored domains of self-perception that best predicted global self-worth and symptom clusters that best predicted second-order factors of self perception. Findings revealed quantitative and qualitative differences in self-complexities, and more positive self-perceptions among the higher ego-level group in scholastic competence, job competence, and behavioral conduct. Results are discussed from a developmental perspective.

Achievement↗
PubMed2001

Hypercapnia invokes an acute loss of contrast sensitivity in untreated glaucoma patients.

BACKGROUND/AIM: It is widely accepted that hypercapnia results in increased retinal, choroidal, and retrobulbar blood flow. Reports of a visual response to hypercapnia appear mixed, with normal subjects exhibiting reduced temporal contrast sensitivity in some studies, while glaucoma patients demonstrate mid-peripheral visual field improvements in others. This suggests that under hypercapnic conditions a balance exists between the beneficial effects of improved ocular blood flow and some other factor such as induced metabolic stress; the outcome may be influenced by the disease process. The aim of this study was to evaluate the contrast sensitivity response of untreated glaucoma patients and normal subjects during mild hypercapnia. METHODS: 10 previously untreated glaucoma patients and 10 control subjects were evaluated for contrast sensitivity and intraocular pressure while breathing room air and then again during mild hypercapnia. RESULTS: During room air breathing, compared with normal subjects, glaucoma patients had higher IOP (p = 0.0003) and lower contrast sensitivity at 3 cycles/degree (cpd) (p = 0.001). Mild hypercapnia caused a significant fall in contrast sensitivity at 6, 12, and 18 cpd (p < 0.05), only in the glaucoma group. CONCLUSION: Glaucoma patients with early disease exhibit central vision deficits as shown by contrast sensitivity testing at 3 cpd. Hypercapnia induces further contrast loss through a range of spatial frequencies (6-18 cpd) which may be predictive of further neuronal damage due to glaucoma.

Case-Control Studies↗
PubMed2001

The Department of Defense chemical and biological defense program: where we are going.

This article provides an overview of the Department of Defense (DoD) Chemical and Biological Defense Program (CBDP). This article highlights the mission and objectives of the DoD CBDP, the general capabilities of systems and technologies being developed or employed to defend U.S. forces against the threat of chemical and biological warfare agents, and improvements made in defensive systems in the years since Operation Desert Storm.

Biological Warfare↗
PubMed2000

Trophic accumulation and depuration of mercury by blue crabs (Callinectes sapidus) and pink shrimp (Penaeus duorarum).

Mercury concentrations in blue crabs (Callinectes sapidus) collected from an area of mercury-contaminated sediments in Lavaca Bay, TX, USA, are more than an order of magnitude greater than concentrations in penaeid shrimp from the same area. Laboratory feeding experiments using mercury-contaminated fish as food showed that both blue crabs and pink shrimp (Penaeus duorarum) could accumulate mercury concentrations comparable to those in their food in 28 days. Calculated mercury assimilation efficiencies averaged 76% for blue crabs and 72% for pink shrimp. Significant depuration of mercury by blue crabs was not observed during a subsequent 28-day period, but pink shrimp lost mercury at a rate of about 0.012 day-1. Model calculations predict biomagnification factors of mercury of about two to three at steady state for both species. The large difference in observed concentrations of mercury in field-collected blue crabs and penaeid shrimp does not result from differences in efficiency of mercury assimilation from their food or from differences in excretion rates. It is more likely the result of differences in residence times in the contaminated area and of differences in feeding habits.

Animals↗
PubMed2000

Developmental aspects of psychological defenses: their relation to self-complexity, self-perception, and symptomatology in adolescents.

This study investigated developmental aspects of psychological defenses in relation to self-complexity, self-perception, and symptomatology through a comparison of two groups of adolescents characterized by defense maturity level (i.e., immature versus mature defenses). The Defense Style Questionnaire (DSQ-78), the Self-Complexity Inventory (SCI), the Self-Perception Profile for Adolescents, and the Youth Self Report behavior checklist (YSR) were completed by 79 high school students ranging in age from 15 to 18 years. Subjects were characterized as either employing predominantly mature or immature defensive strategies based on median splits of the two defense factors. Dependent variables included the Self-Complexity Inventory, The Youth Self Report and the Self-Perception Profile for Adolescents. The mature defense group (N = 26) reported significantly higher self-complexity than the immature defense group (N = 26), supporting a developmental approach to defense mechanisms. In general, mature defense mechanisms seem to be more adaptive in late adolescence than immature defenses as indicated by higher global self-worth and fewer internalizing and externalizing symptoms. The findings lend support to the developmental approach to the self and highlight the importance of examining psychological indices of development independent of chronological age.

Adaptation, Psychological↗
PubMed1999

Vascular aspects in the pathophysiology of glaucomatous optic neuropathy.

Glaucoma remains a major eye illness with unknown etiology. Although elevated intraocular pressure is clearly a major risk factor, vascular deficits may contribute to initiation and progression of glaucoma. When intraocular pressure is acutely elevated in healthy individuals, the resistance index (derived from the peak systolic and end-diastolic velocities and an indirect index of vascular resistance distal to the site of measurement) in the central retinal and posterior ciliary arteries increases progressively. This result implies that mechanical and vascular factors may be coupled in such a way that perfusion of the retina and optic nerve head may be influenced by changes in the intraocular pressure. Further, at night, when ophthalmic artery flow velocities fall as arterial blood pressure falls in glaucoma patients, the risk of disease progression may be increased. The constancy of these same flow velocities in age-matched healthy individuals points to a possible vascular autoregulatory defect in glaucoma. In addition, in normal-tension glaucoma, vasodilation (CO2 inhalation) normalizes retrobulbar arterial flow velocities, hinting that some vascular deficits in glaucoma may be reversible. Finally, Ca2+ channel blockade improves contrast sensitivity in patients with normal-tension glaucoma, who also show increased retrobulbar vessel flow velocities, a result suggesting that visual function loss may be linked to ocular ischemia. Emerging evidence points to a role of ischemia in the pathogenesis of glaucoma, suggesting that treatments designed to improve ocular blood flow may benefit glaucoma patients.

Animals↗
PubMed1999

The rituals, fears and phobias of young children: insights from development, psychopathology and neurobiology.

This study examined the relationship between ritualistic, compulsive-like behaviors and normative fears and phobias in 61 children ranging from 1 to 7 years of age. Parents reported on their children's ritualistic habits, and perfectionistic behaviors that reflect what we have previously called "compulsive-like" behaviors. Parents also reported on their children's fears and phobias. Results indicated that various aspects of children's ritualistic and compulsive-like behaviors are correlated with children's fears and phobias. Developmental differences existed such that younger children's (< 4 years) repetitive, compulsive-like behaviors were related to "prepotent" fears such as stranger and separation anxieties, whereas the compulsive-like behaviors of older children (> 4 years) were correlated with more specific, "contextual" fears such as fears of contamination, death, and fears often associated with concerns of the inner city such as burglars, assault, etc. These findings are discussed in terms of the phenomenologic and possible neurobiological continuities between normative and pathologic rituals, fears and phobias.

Ceremonial Behavior↗
PubMed1999

Primary open-angle glaucoma patients characterized by ocular vasospasm demonstrate a different ocular vascular response to timolol versus betaxolol.

We evaluated the retrobulbar response to a selective versus nonselective beta blocker in a subgroup of primary open-angle glaucoma patients (POAG) characterized by ocular vasospasm. Eleven patients who exhibited ocular vasospasm (i.e. a significant increase in ophthalmic artery blood flow velocity or a significant decrease in ophthalmic artery resistance index during hypercapnia) underwent medication washout for 4 weeks and were enrolled in a double-masked cross-over study (betaxolol versus timolol). Patients were evaluated for blood flow velocity of the retrobulbar vessels using color Doppler imaging, intraocular pressure, visual field sensitivity and contrast sensitivity at the beginning and end of each 4 week treatment period. Timolol treatment caused a significant reduction in IOP (p = .007), but no change in retrobulbar hemodynamics or visual function. After betaxolol treatment, resistance index fell significantly (p = .040) in the ophthalmic artery and increased significantly in both the central retinal (p = .003) and temporal posterior ciliary arteries (p = .030). Also following betaxolol treatment, contrast sensitivity improved significantly (p = .006), and a significant positive correlation was shown between change in contrast sensitivity and change in resistance index (r = .70; p = .015) of the ciliary arteries. POAG patients characterized by ocular vasospasm display a significant hemodynamic response to betaxolol, but not to timolol.

Adrenergic beta-Antagonists↗
PubMed1999

Early parental preoccupations and behaviors and their possible relationship to the symptoms of obsessive-compulsive disorder.

This study focuses on early parental preoccupations and behaviors (EPPB) surrounding the birth of a new family member. An interview instrument was developed to assess EPPB at eight months prepartum and two weeks and three months postpartum. Measures with adequate psychometric and conceptual properties were used to assess the overall level of parental preoccupations and associated actions as well as three content domains: caregiving (CARE), relationship building (RELATIONSHIP), and anxious intrusive thoughts associated with harm avoidant behaviors (AITHAB). The hypothesis that preoccupations and behaviors would peak for both parents close to the birth of the child was confirmed. Measures of EPPB were distinguished from symptoms of depression and generalized anxiety. Consistent with our a priori hypothesis the content and character of the AITHAB was found to resemble the symptoms of obsessive-compulsive disorder (OCD). The study findings suggest the potential adaptive significance of EPPB and the possible evolutionary origins of OCD.

Adult↗
PubMed1999

Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change.

BACKGROUND/AIMS: Autoregulation of blood flow during posture change is important to ensure consistent organ circulation. The purpose of this study was to compare the change in retrobulbar ocular blood flow in glaucoma patients with normal subjects during supine and upright posture. METHODS: 20 open angle glaucoma patients and 20 normal subjects, similar in age and sex distribution, were evaluated. Blood pressure, intraocular pressure, and retrobulbar blood velocity were tested after 30 minutes of sitting and again after 30 minutes of lying. Retrobulbar haemodynamic measures of peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) were obtained in the ophthalmic and central retinal arteries using colour Doppler imaging (CDI). RESULTS: When changing from the upright to supine posture, normal subjects demonstrated a significant increase in OA EDV (p = 0.016) and significant decrease in OA RI (p = 0.0006) and CRA RI (p = 0.016). Glaucoma patients demonstrated similar changes in OA measures of EDV (p = 0.02) and RI (p = 0.04), but no change in CRA measures. CONCLUSION: Glaucoma patients exhibit faulty autoregulation of central retinal artery blood flow during posture change.

Blood Flow Velocity↗
PubMed1999

Effects of long-term hypotensive therapy with nonselective beta-blockers on ocular hemodynamics in primary open-angle glaucoma.

PURPOSE: Vascular factors have been implicated in the progression of glaucoma, but the impact of long-term beta blocker therapy on ocular circulation remains largely undefined. The purpose of this study was to prospectively evaluate the level of retrobulbar blood flow in patients with primary open-angle glaucoma (POAG) before and during long-term treatment with a nonselective topical beta blocker, and to compare these measures with those in untreated control subjects. METHODS: Twelve control subjects and 12 patients with POAG were tested for intraocular pressure (IOP), heart rate, blood pressure, contrast sensitivity, visual field sensitivity, and retrobulbar flow velocity as measured by color Doppler imaging (CDI). Patients were evaluated after 4 weeks of drug washout and again after 3 and 6 months of treatment with a nonselective beta blocking agent. Control subjects were tested once. RESULTS: At baseline, patients with POAG had significantly higher IOP than normal controls; CDI measures of the central retinal artery (CRA) and short posterior ciliary artery (SPCA) in the patients were significantly different from those in control subjects. In the patients, treatment resulted in a significant reduction in IOP and in CRA and SPCA resistance index. CONCLUSION: Untreated patients with POAG have altered circulation in the CRA and SPCA compared with subjects of similar age and gender. These measures recover significantly during topical beta blocker therapy. The relationship of the pretreatment deficit and posttreatment recovery of CDI blood flow measures to the progression and therapeutic impediment of glaucomatous optic nerve deterioration remains to be determined.

Adrenergic beta-Antagonists↗