Search PubMed⌕ Search

Biomedical subjects

J O'Brien

Publications and source records attributed to J O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed2002

Fluctuations in attention: PD dementia vs DLB with parkinsonism.

BACKGROUND: Marked impairments in and fluctuation of attention are characteristic of dementia with Lewy bodies (DLB). The comparative impairment of these cognitive domains in PD and PD dementia (PD dementia) has not been studied, and is important to the conceptual understanding of parkinsonian dementias. METHOD: Detailed evaluations of attention and fluctuating attention (Cognitive Drug Research computerized battery) were undertaken in 278 subjects (50 DLB, 48 PD dementia, 50 PD, 80 AD, 50 elderly controls) from the Newcastle dementia register and the Stavanger PD register (controls, PD, and PD dementia patients were recruited from both centers). DLB, AD, PD, and PD dementia were diagnosed using operationalized criteria. RESULTS: Impairments in reaction time, vigilance, and fluctuating attention were comparable in patients with DLB and PD dementia, but were less substantially impaired in patients with DLB without parkinsonism. Patients with PD had significantly greater impairment of cognitive reaction time than elderly controls, and comparable impairments of cognitive reaction time to patients with AD. Patients with PD, however, did not exhibit fluctuation of attention. CONCLUSION: The profile of attentional impairments and fluctuating attention is similar in PD dementia and DLB with parkinsonism. The current findings do not support the current arbitrary distinctions between these patient groups. Importantly, patients with PD do not experience fluctuating attention.

Aged↗
PubMed2002

Mechanical environment, donor age, and presence of endothelium interact to modulate porcine artery viability ex vivo.

Though ex vivo culture of arteries is a widely used model of native arteries and is closely aligned with efforts to generate tissue-engineered arteries, the effects of culture conditions on artery viability are poorly characterized. To investigate factors regulating long-term viability of cultured arteries, carotid arteries from neonatal and adolescent pigs were perfused for up to 27 days with steady laminar flow ranging from approximately 2% to approximately 200% of physiological flow rates. Arteries from neonatal animals (2 weeks old, approximately 5 kg) were susceptible to spontaneous progressive endothelial denudation followed by deterioration of the vessel wall that spread from luminal to abluminal regions. Subphysiological levels of flow and pressure abrogated this deterioration. Arteries harvested from adolescent (6 months old, approximately 100 kg) animals maintained viability and retained structure for at least 9 days as assessed by normal histology, presence of intact endothelium, normal mitochondrial activity, and low levels of cell death and proliferation, unless the vessels were subjected to superphysiological levels of flow or the endothelium was intentionally denuded. Adolescent arteries perfused at subphysiological, but not physiological, flow rates maintained viability and normal structure for at least 27 days. These data indicate that under the appropriate conditions, arteries may be cultured long term but careful attention to the viability is merited.

Age Factors↗
PubMed2002

Volumetric MRI study of the caudate nucleus in patients with dementia with Lewy bodies, Alzheimer's disease, and vascular dementia.

OBJECTIVES: To determine whether parkinsonian symptoms in dementia with Lewy bodies (DLB) are associated with greater atrophy of the caudate nucleus in comparison with patients with Alzheimer's disease (AD) and vascular dementia (VaD). METHODS: T1weighted MR scans were acquired in elderly patients with DLB, AD, VaD, and healthy controls. Normalised volumetric measurements of the caudate nucleus were obtained and parkinsonian symptoms rated using Hoehn and Yahr staging. RESULTS: There were no significant differences in the volume of the caudate nucleus between patients with dementia. However, the left caudate volume was significantly reduced in AD and DLB compared with controls. Parkinsonian symptoms did not correlate with caudate nucleus volume. CONCLUSIONS: Parkinsonian symptoms in DLB may be more closely coupled to neurochemical rather than structural changes in the caudate nucleus, and volumetric MRI analysis of caudate nucleus does not discriminate between patients with DLB, AD, and VaD.

Aged↗
PubMed2002

Omalizumab provides long-term control in patients with moderate-to-severe allergic asthma.

The ability of omalizumab, an anti-immnoglobulin-E agent, to maintain long-term disease control in patients with moderate-to-severe allergic asthma was investigated in a 24-week double-blind extension to a 28-week core trial. During the extension, 483 of the initial 546 patients were maintained on randomised treatment and the lowest sustainable dose of beclomethasone dipropionate (BDP) as established during the steroid-reduction phase of the core trial. The use of concomitant asthma medication was permitted and investigators were allowed to adjust the BDP dose or switch patients from BDP to other asthma medications if deemed necessary. More omalizumab-treated patients (33.5%) than placebo-treated patients (13.5%) were able to complete the extension period without requiring inhaled corticosteroid treatment. The mean BDP equivalent dose throughout the extension was lower in the omalizumab group (25 microg x day(-1)) than in the placebo group (43 microg x day(-1)). Disease control was sustained in 76% of omalizumab patients compared with 59.4% of placebo patients free from an asthma exacerbation during the extension period. Compared with placebo, fewer patients in the omalizumab group used other concomitant asthma medication during the extension. Treatment with omalizumab was well tolerated and the incidence of adverse events was similar between groups. In conclusion, these results suggest that omalizumab is a promising new agent for the long-term control of allergic asthma.

Adolescent↗
PubMed2002

Developing, evaluating and maintaining a standardized stormwater BMP effectiveness database.

The Urban Water Resources Research Council of the American Society of Civil Engineers, under a cooperative agreement with the US Environmental Protection Agency, released Version 1.0 of the National Stormwater Best Management Practices (BMP) Database to the stormwater management community in 1999. The product included a loaded database of 71 BMPs, as well as data entry software for standardized reporting of BMP test data. In conjunction with the database, the project team developed BMP performance evaluation protocols and applied them to the data contained in the initial database. Since the initial database release, 42 new BMP data sets have been added to the database, which is now accessible via the Internet at www.bmpdatabase.org along with associated data evaluation reports and other project documentation. A national stormwater BMP data clearinghouse continues to screen and post new BMP data to the database, as well as respond to inquiries from the public. An overview of both of the database software and results of the data evaluation are provided in this paper.

Databases, Factual↗
PubMed2001

Anion directed assembly of a dinuclear double helicate.

The synthesis and structural characterisation of the diamino-bis-pyridine ligand L2 and its diammonium-bispyridinium salt [(H4L2Cl)2].6Cl.H2O 1, are reported; X-ray diffraction studies reveal that chloride coordination causes the latter to adopt a double-helicate structure in the solid-state.

Journal Article↗
PubMed2001

Facial electromyographic (EMG) responses to emotionally significant visual images: differences between light and heavy drinkers.

Fifty participants took part in an experiment designed to investigate individual differences in the effects of alcohol on facial EMG responses to emotionally significant stimuli. Participants took part in two experimental sessions during which they viewed emotionally negative and emotionally positive visual images. In one session they consumed alcohol (0.5 g/kg bodyweight) whilst in the other they consumed soft drink. We classified each participant as a light or heavy drinker on the basis of their self-reported alcohol consumption. Negatively valenced images elicited increases in both frontalis and corrugator activity but alcohol did not moderate this effect either in light or heavy drinkers. Nevertheless, heavy drinkers did respond more strongly to the negatively valenced images and this supports the view that responses to negative emotional stimuli may play a part in the development of heavy drinking as a result of negative reinforcement processes.

Adult↗
PubMed2001

Rod pathways in the mammalian retina use connexin 36.

Many neurons in the mammalian retina are coupled by means of gap junctions. Here, we show that, in rabbit retina, an antibody to connexin 36 heavily labels processes of AII amacrine cells, a critical interneuron in the rod pathway. Image analysis indicates that Cx36 is primarily located at dendritic crossings between overlapping AII amacrine cells. This finding suggests that Cx36 participates in homotypic gap junctions between pairs of AII amacrine cells. Cx36 was also found at AII/cone bipolar contacts, previously shown to be gap junction sites. This finding suggests that Cx36 participates at gap junctions that may be heterotypic. These results place an identified neuronal connexin in the context of a well-defined retinal circuit. The absence of Cx36 in many other neurons known to be coupled suggests the presence of additional unidentified connexins in mammalian neurons. Conversely, Cx36 labeling in other regions of the retina is not associated with AII amacrine cells, indicating some other cell types use Cx36.

Animals↗
PubMed2001

RNomics: an experimental approach that identifies 201 candidates for novel, small, non-messenger RNAs in mouse.

In mouse brain cDNA libraries generated from small RNA molecules we have identified a total of 201 different expressed RNA sequences potentially encoding novel small non-messenger RNA species (snmRNAs). Based on sequence and structural motifs, 113 of these RNAs can be assigned to the C/D box or H/ACA box subclass of small nucleolar RNAs (snoRNAs), known as guide RNAs for rRNA. While 30 RNAs represent mouse homologues of previously identified human C/D or H/ACA snoRNAs, 83 correspond to entirely novel snoRNAS: Among these, for the first time, we identified four C/D box snoRNAs and four H/ACA box snoRNAs predicted to direct modifications within U2, U4 or U6 small nuclear RNAs (snRNAs). Furthermore, 25 snoRNAs from either class lacked antisense elements for rRNAs or snRNAS: Therefore, additional snoRNA targets have to be considered. Surprisingly, six C/D box snoRNAs and one H/ACA box snoRNA were expressed exclusively in brain. Of the 88 RNAs not belonging to either snoRNA subclass, at least 26 are probably derived from truncated heterogeneous nuclear RNAs (hnRNAs) or mRNAS: Short interspersed repetitive elements (SINEs) are located on five RNA sequences and may represent rare examples of transcribed SINES: The remaining RNA species could not as yet be assigned either to any snmRNA class or to a part of a larger hnRNA/mRNA. It is likely that at least some of the latter will represent novel, unclassified snmRNAS:

Animals↗
PubMed2001

Cognitive impairment in depression is not associated with neuropathologic evidence of increased vascular or Alzheimer-type pathology.

BACKGROUND: Cognitive impairment is common in depression, but underlying mechanisms remain unknown. We examined whether increases in Alzheimer-type or vascular pathology are associated with cognitive impairments in elderly depressed subjects. METHODS: Eleven subjects who had died during a well-documented episode of DSM-IV major depression were included. Neuropathologic assessments, blind to group membership, included standardized assessment of neuritic plaques, neurofibrillary tangles, and Lewy Bodies in frontal, temporal, parietal, and occipital cortices. Braak staging of Alzheimer pathology was also performed. Cerebral microvascular disease was scored according to a previously validated scale, and a score for cerebral and systemic atheroma of large and medium sized arteries was obtained. RESULTS: No subject had Lewy bodies. Plaque and tangle counts for all subjects were well within published norms for age-matched control subjects. There were no significant differences in plaque or tangle counts between subjects who were cognitively impaired (n = 5) and those who were nonimpaired (n = 6) during their depressive illness. Similarly, neither total microvascular pathology nor deep frontal microvascular pathology differed between the two groups. CONCLUSIONS: Our results indicate that the liability for some patients to develop cognitive impairment during a depressive episode is not related to an increase in Alzheimer-type or vascular neuropathologic change. This indicates that other mechanisms must underlie both the cognitive impairment associated with depression and the observation that depression is a risk factor for dementia.

Aged↗
PubMed2001

Attention and fluctuating attention in patients with dementia with Lewy bodies and Alzheimer disease.

BACKGROUND: Attentional deficits are described in the consensus clinical criteria for the operationalized diagnosis of dementia with Lewy bodies (DLB) as characteristic of the condition. In addition, preliminary studies have indicated that both attentional impairments and fluctuation of attentional impairments are more marked in patients with DLB than in patients with Alzheimer disease (AD), although neuropsychological function has not previously been examined in a large prospective cohort with confirmed diagnostic accuracy against postmortem diagnosis. METHODS: A detailed evaluation of attention and fluctuating attention was undertaken in 155 patients with dementia (85 with DLB and 80 with AD) from a representative hospital dementia case register and 35 elderly controls using the Cognitive Drug Research Computerized Assessment System for Dementia Patients computerized neuropsychological battery. Operationalized clinical diagnosis was made using the consensus criteria for DLB and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD. High levels of sensitivity and specificity have been achieved for the first 50 cases undergoing postmortem examination. RESULTS: The groups were well matched for severity of cognitive impairments, but the AD patients were older (mean age, 80 vs 78 years) and more likely to be female (55% vs 40%). Patients with DLB were significantly more impaired than patients with AD on all measures of attention and fluctuating attention (for all comparisons, t > or = 2.5, P<.001), and patients from both dementia groups were significantly more impaired than elderly controls for all comparisons other than cognitive reaction time, which was significantly more impaired in DLB patients than controls but was comparable in controls and AD patients. There were, however, significant associations between the severity of cognitive impairment and the severity of both attentional deficits and fluctuations in attention. CONCLUSIONS: This large prospective study confirms that slowing of cognitive processing, attention, and fluctuations of attention are significantly more pronounced in DLB and AD patients, although fluctuating attention is common in patients with moderate-to-severe AD. Deficits of cognitive reaction time appear to be specific to DLB, except in severe dementia. A detailed evaluation of attentional performance could make an important contribution to differential diagnosis, although the results need to be interpreted within the context of the overall severity of cognitive deficits.

Aged↗
PubMed2001

Reconstruction with rectus abdominis myocutaneous free flap after orbital exenteration in children.

OBJECTIVE: To present a 1-stage technique for orbital reconstruction after exenteration with the use of myocutaneous rectus abdominis free flap in children. SURGICAL TECHNIQUE: After orbital exenteration, a myocutaneous rectus abdominis free flap with long vascular pedicle is harvested from the abdomen. The flap is transferred to the orbit and the vascular pedicle is passed through an opening made in the lateral orbital wall, where it is anastomosed to superficial temporal vessels. The skin of the flap is trimmed to correspond to the eyelid defect and the incisions are closed. METHODS: After informed consent was obtained, 2 children, 3 and 8 years old, underwent orbital reconstruction with a rectus abdominis free flap after exenteration for orbital rhabdomyosarcoma and orbital osteosarcoma in the setting of retinoblastoma. RESULTS: This technique allowed easy postoperative wound care. Viability of the flap was excellent. The technique provided sufficient volume to fill the orbit, with improved aesthetic results and minimal donor site deformity. CONCLUSIONS: The postoperative care and aesthetic outcome in patients with rectus abdominis free flap after exenteration are much improved over those provided with traditional surgical techniques. This primary reconstruction is recommended for any patient requiring orbital exenteration, but particularly for pediatric patients who tolerate debridement of traditional exenteration sites poorly.

Child↗
PubMed2001

Prevalence and pharmacological management of behavioural and psychological symptoms amongst dementia sufferers living in care environments.

BACKGROUND: Behavioural and psychological symptoms in dementia (BPSD) are a common reason for placement in long term care and are often associated with indiscriminate prescription of psychotropic medication. AIMS: To determine the prevalence of BPSD in care environments, their relationship with severity of dementia and the pattern of psychotropic medication. METHODS: Two hundred and thirty-one elderly residents (39% living in social care facilities and 61% in nursing home care) were assessed using a range of standardised psychiatric schedules. Additional information about the residents and medication was obtained from professional carers. RESULTS: Overall 90% of residents had dementia, 79% of whom had clinically significant BPSD with 58% receiving psychotropic medication. There was no difference in the prevalence of BPSD between social and nursing care. Depression was most common in people with mild dementia, whilst delusions arose most frequently in those with moderate dementia and aberrant motor behaviour had a high prevalence in people with severe dementia. CONCLUSION: BPSD are common in elderly people with dementia living in care environments. More rigorous guidelines are needed pertaining to the prescription and monitoring of medication and the need to disseminate skills regarding psychosocial management approaches to care staff.

Aged↗
PubMed2001

The characterisation and impact of 'fluctuating' cognition in dementia with Lewy bodies and Alzheimer's disease.

BACKGROUND: Case reports and clinical observations suggest that fluctuating cognition (FC) is common in all the major dementias, particularly dementia with Lewy bodies (DLB) where it is one of three core clinical diagnostic features. The purpose of this study was to characterise FC and determine its impact upon activities of daily living. METHODS: Forty matched subjects (15 DLB, 15 AD, 10 elderly controls) were assessed using the activities of daily living scale (ADLD), the cognitive drug research (CDR) computerised neuropsychological test battery and a semi-standardised assessment of FC. The CDR battery was completed three times across a 1-week period, to evaluate variability in attention, visuospatial ability, working memory and delayed recall. RESULTS: There was a strong positive correlation between clinical FC scores and total mean ADLD. Measures of cognitive variability also demonstrated strong significant correlations with independent clinical severity ratings of FC across several cognitive domains. These associations were most powerful between attentional measures and clinical FC ratings. CONCLUSIONS: Although attention is the cognitive domain which fluctuates most markedly, other cognitive domains are also affected. FC also has a significant independent impact on activities of daily living.

Activities of Daily Living↗
PubMed2001

The progression of cognitive impairment in dementia with Lewy bodies, vascular dementia and Alzheimer's disease.

BACKGROUND: Little is known about the rate of progression or associations of cognitive impairment in dementia with Lewy bodies (DLB), or the associations of accelerated decline. METHOD: Dementia patients from a case register were evaluated at baseline and 1 year follow-up using the Cambridge Assessment for Mental Disorders in the Elderly, section B (CAMCOG) and the Mini-Mental State Examination (MMSE) to determine the rate of cognitive decline. Operationalized clinical diagnoses were applied (NINCDS ADRDA for Alzheimer's disease (AD), NINCDS AIRENS for vascular dementia (VaD) and consensus criteria for DLB). RESULTS: One hundred and ninety-three patients completed annual MMSE schedules (AD, 101; DLB, 64; VaD, 38), of whom 154 completed the CAMCOG. The magnitude of cognitive decline (MMSE, 4-5 points; CAMCOG, 12-14 points) was similar in each of the dementias. The strongest predictor of accelerated cognitive decline in DLB was the apolipoprotein E4 allele (17.5 vs 8.3 points decline on the CAMCOG). CONCLUSION: Over 1 year, DLB, VaD and AD patients had similar rates of cognitive decline overall. Apolipoprotein E4 may be an important predictor of more rapid decline in DLB.

Aged↗