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Biomedical subjects

K M Robinson

Publications and source records attributed to K M Robinson.

At least 19 recordsLinked to original sources
PubMed2006

Cognitive functioning in sporadic amyotrophic lateral sclerosis: a six month longitudinal study.

OBJECTIVE: To observe changes in cognition over six months in subjects with recently diagnosed sporadic amyotrophic lateral sclerosis (ALS). METHODS: The study used a between-group and within-group longitudinal design. Nineteen ALS subjects and eight matched caregivers were recruited to participate in baseline neuropsychological assessments that were repeated six months later. Between group comparisons for these variables were undertaken at baseline and six months later. Within group/across time comparisons for these variables were carried out for both groups. Individual analyses for the neuropsychological variables using z scores were done for the ALS subjects using their baseline performance as the basis for comparison with their six month performance. RESULTS: The between-group and within-group comparisons did not show significant differences in cognitive function over time. In individual analyses, however, seven of 19 ALS subjects (36.84%) developed abnormal neuropsychological performance over six months. CONCLUSIONS: Early in the disease course, over one third of the ALS subjects developed cognitive deficits over six months. These findings support the hypothesis that cognitive deficits in ALS become more prominent over time.

Aged↗
PubMed2002

Leaf stomatal and epidermal cell development: identification of putative quantitative trait loci in relation to elevated carbon dioxide concentration in poplar.

Genetic variation in stomatal initiation and density, and epidermal cell size and number were examined in a hybrid pedigree of Populus trichocarpa T. & G. and P. deltoides Marsh in both ambient ([aCO2]) and elevated ([eCO2]) concentrations of CO2. We aimed to link anatomical traits with the underlying genetic map of F2 Family 331, composed of 350 markers across 19 linkage groups. Leaf stomatal and epidermal cell traits showed pronounced differences between the original parents. We considered the following traits in the F2 population: stomatal density (SD), stomatal index (SI), epidermal cell area (ECA) and the number of epidermal cells per leaf (ECN). In [eCO2], adaxial SD and SI were reduced in the F2 population, whereas ECA increased and ECN remained unchanged. In [aCO2], four putative quantitative trait loci (QTL) with logarithm of the odds ratio (LOD) scores greater than 2.9 were found for stomatal traits on linkage group B: adaxial SI (LOD scores of 5.4 and 5.2); abaxial SI (LOD score of 3.3); and SD (LOD score of 3.2). These results imply that QTL for SI and SD share linkage group B and are under genetic control. More moderate LOD scores (LOD scores >/= 2.5) suggest QTL for SI on linkage groups A and B and for SD on linkage groups B, D and X with a probable co-locating quantitative trait locus for SI and SD on linkage group D (position 46.3 cM). The QTL in both [aCO2] and [eCO2] for adaxial SD were co-located on linkage group X (LOD scores of 3.5 and 2.6, respectively) indicating a similar response across both treatments. Putative QTL were located on linkage group A (position 89.2 cM) for both leaf size and ECN in [aCO2] and for ECA at almost the same position. The data provide preliminary evidence that leaf stomatal and cell traits are amenable to QTL analysis.

Carbon Dioxide↗
PubMed2001

Problem behaviour, caregiver reactions, and impact among caregivers of persons with Alzheimer's disease.

BACKGROUND: Problem behaviours that occur during Alzheimer's disease (AD) can have major impact on caregivers. How caregivers react to these behaviours may determine the total impact experienced from caregiving. PURPOSE: This study examined the relationships between problematic behaviours and caregiving impact in 30 primary caregivers of persons with AD. The first question explored the relationship between frequency of problem behaviour and impact; the second explored the relationship between caregiver reactions to problem behaviours and impact from caregiving. METHODS: The frequency of problem behaviour and the caregiver reaction was measured using The Revised Memory and Behaviour Problem Checklist (Teri et al. 1992). The impact from caregiving was operationalized using the Cost of Care Index developed by Kosberg and Cairl (1986). RESULTS: Significant associations were found for 11 of the 20 subscales that measured the association between the frequency of problem behaviour in the client and the impact from caregiving experienced by the caregiver. In comparison, the association between caregiver's reaction to problem behaviours and impact from caregiving was even more significant in value with 15 subscales of 20 being significant. Female caregivers experienced a greater reaction to disruptive and depressive behaviour when compared with male caregivers even though both genders reported similar frequencies of problem behaviours. In regard to findings about the impact from caregiving, four of the six indicators were higher for women than for men. CONCLUSIONS: Caregiver reaction to problem behaviours was more highly associated with impact from caregiving than the actual frequency of the behaviours. These findings have great implications for intervention programs. Caregivers, especially females, need to receive individualized, specific education/training on how to understand and manage disruptive and depressive behaviour in persons with AD.

Adult↗
PubMed2001

Unsolicited narratives from the Internet: a rich source of qualitative data.

Recently, the Internet has become a forum for informal communication. Many--whose voices may have been unheard--can now express themselves through this medium. Rich narratives are available to the qualitative researcher from bulletin boards, guestbooks, Web pages, and listservs on the Internet. In this article, these data sources are defined and described. Strategies for using these data are discussed. One concern with using unsolicited data from the Internet is the protection of human subjects and the requirement for consent. A proposed model describing the process for deciding when such data are publicly available, as defined by the Office for the Protection of Rights of Research Subjects, and when the use of the data requires consent is presented.

Data Collection↗
PubMed1999

Respite care--volunteers as providers.

1. Although many studies examine the impact of respite care on caregivers, few studies have examined the impact of such programs on the volunteer respite provider. Results of such formative evaluation studies must be antecedent to the question of whether respite care "works." 2. Fear of persons with Alzheimer's Disease (AD) was a consistent theme verbalized in this study. Educational programs must therefore include more exposure to actual persons with AD. 3. Caregivers with some past experience composed the majority of volunteers in this group (n = 78%). Recruiting former caregivers of deceased persons with AD may be fruitful future areas of study.

Adult↗
PubMed1998

Chromatin, TAFs, and a novel multiprotein coactivator are required for synergistic activation by Sp1 and SREBP-1a in vitro.

The promoter selectivity factor Sp1 often cooperates with other enhancer-binding proteins to activate transcription. To study the molecular underpinnings of these regulatory events, we have reconstituted in vitro the synergy observed in vivo between Sp1 and the sterol-regulated factor SREBP-1a at the low density lipoprotein receptor (LDLR) promoter. Using a highly purified human transcription system, we found that chromatin, TAFs, and a novel SREBP-binding coactivator activity, which includes CBP, are all required to mediate full synergistic activation by Sp1 and SREBP-1a. The SREBP-binding domain of CBP inhibits activation by SREBP-1a and Sp1 in a dominant-negative fashion that is both chromatin- and activator-specific. Whereas recombinant CBP alone is not sufficient to mediate activation, a human cellular fraction containing CBP can support high levels of chromatin-dependent synergistic activation. Purification of this activity to near homogeneity resulted in the identification of a multiprotein coactivator, including CBP, that selectively binds to the SREBP-1a activation domain and is capable of mediating high levels of synergistic activation by SREBP/Sp1 on chromatin templates. The development of a reconstituted chromatin transcription system has allowed us to isolate a novel coactivator that is recruited by the SREBP-1a activation domain and that functions in concert with TFIID to coordinate the action of multiple activators at complex promoters in the context of chromatin.

Animals↗
PubMed1997

The COQ5 gene encodes a yeast mitochondrial protein necessary for ubiquinone biosynthesis and the assembly of the respiratory chain.

Saccharomyces cerevisiae is a facultative anaerobe capable of meeting its energy requirements by fermentation and is thus an ideal system for studying the biogenesis of respiring mitochondria. We have isolated a respiration-deficient mutant exhibiting a pleiotropic loss of the mitochondrial electron transport chain. The corresponding wild-type gene, COQ5, was cloned, sequenced, and able to restore respiratory growth. Deletion of the chromosomal COQ5 gene results in a respiration deficiency and reduced levels of respiratory protein components. Exogenously added decylubiquinone can partially restore electron transport chain function to mitochondrial membranes from the deletion mutant. The COQ5 nucleotide sequence predicts a polypeptide of 307 amino acids containing a mitochondrial targeting signal. COQ5p is 43% identical to the polypeptide predicted by the Escherichia coli open reading frame, o251 (1). The COQ5 gene, when introduced into E. coli, complements the respiratory deficiency of an ubiE mutant that maps near o251, suggesting that it is the yeast homolog of the ubiE gene product. We conclude that the COQ5 gene encodes the mitochondria-localized 2-hexaprenyl-6-methoxy-1,4-benzoquinone methyltransferase of the yeast ubiquinone biosynthetic pathway.

Amino Acid Sequence↗
PubMed1997

Lexical acquisition in probable Alzheimer's disease.

Patients with probable Alzheimer's disease (pAD) were exposed to a new verb in a naturalistic fashion. We probed their knowledge of the word's semantic and grammatical characteristics for several minutes following this exposure, and compared this with their performance on parallel measures assessing known words. Significant differences were seen between pAD patients and controls in the acquisition of the new verb's semantic meaning and its argument structure, but pAD patients did not differ from controls in the acquisition of the new word's grammatical form class. Individual patient analyses demonstrated parallel deficits restricted to the semantic meaning and argument structure of the new word and known words in several pAD patients, suggesting that a selective language impairment contributed to their word learning deficit. This pattern is consistent with an intimate relationship between semantic meaning and argument structure in semantic memory. Other pAD patients had difficulty learning about all aspects of the new word, despite good performance with known words, suggesting that compromised memory may have limited their lexical acquisition.

Aged↗
PubMed1997

The family's role in long-term care.

Long-term care provided by family members is the central care of our current health care system. The purpose of this article is to review the family's role in long-term care. Issues such as cost containment and inequities in our current social policy are reviewed. Suggestions for future directions in social policy are presented.

Aged↗
PubMed1996

Covalent attachment of FAD to the yeast succinate dehydrogenase flavoprotein requires import into mitochondria, presequence removal, and folding.

Succinate dehydrogenase (EC 1.3.99.1) in the yeast Saccharomyces cerevisiae is a mitochondrial respiratory chain enzyme that utilizes the cofactor, FAD, to catalyze the oxidation of succinate and the reduction of ubiqinone. The succinate dehydrogenase enzyme is a heterotetramer composed of a flavoprotein, an iron-sulfur protein, and two hydrophobic subunits. The FAD is covalently attached to a histidine residue near the amino terminus of the flavoprotein. In this study, we have investigated the attachment of the FAD cofactor with the use of an antiserum that specifically recognizes FAD and hence, can discriminate between apo- and holoflavoproteins. Cofactor attachment, both in vivo and in vitro, occurs within the mitochondrial matrix once the presequence has been cleaved. FAD attachment is stimulated by, but not dependent upon, the presence of the iron-sulfur subunit and citric acid cycle intermediates such as succinate, malate, or fumarate. Furthermore, this modification does not occur with C-terminally truncated flavoprotein subunits that are fully competent for import. Taken together, these data suggest that cofactor addition occurs to an imported protein that has folded sufficiently to recognize both FAD and its substrate.

Citric Acid Cycle↗
PubMed1996

A requirement for matrix processing peptidase but not for mitochondrial chaperonin in the covalent attachment of FAD to the yeast succinate dehydrogenase flavoprotein.

Succinate dehydrogenase (EC 1.3.99.1) in the yeast Saccharomyces cerevisiae is a mitochondrial heterotetramer containing a flavoprotein subunit with an 8alpha-N(3)-histidyl-linked FAD cofactor. The covalent linkage of the FAD is necessary for activity. We have developed an in vitro assay that measures the flavinylation of the flavoprotein precursor in mitochondrial matrix fractions. Flavoprotein modification does not depend on translocation across a membrane, but it does require proteolytic processing by the mitochondrial processing peptidase prior to flavin attachment. Since ATP depletion, N-ethylmaleimide, or proteinase treatments of matrix fractions inhibit flavoprotein modification, at least one additional matrix protein component appears to be required. Having previously suggested that the flavoprotein begins folding before FAD attachment occurs, we tested whether the mitochondrial chaperonin, heat shock protein 60, might be necessary. Co-immunoprecipitation of the flavoprotein and the chaperonin demonstrate that the proteins do indeed interact. However, immunodepletion of the chaperonin from matrix fractions does not inhibit FAD attachment. Nonprotein components are also required for flavoprotein modification. In addition to ATP, effector molecules such as succinate, fumarate, or malate also stimulate modification. Together, these results suggest that FAD addition is an early event in succinate dehydrogenase assembly.

Adenosine Triphosphate↗
PubMed1996

Anomaly judgments of subject-predicate relations in Alzheimer's disease.

Claims that patients with probable Alzheimer's disease (AD) have semantic memory difficulty have received equivocal support. A common assumption has been that defining or core information determines the truth value of word meaning on measures requiring semantic memory such as category membership judgments or confrontation naming, but this assumption may not be valid. In the present study, we assessed the comprehension of subject-predicate sentences independent of their truth value by asking AD patients to judge the coherence of statements such as "The tulip is tall" or "*The tulip is jealous." We found that AD patients are significantly more impaired than controls at judging the coherence of these simple subject-predicate sentences. Moreover, AD patients were more successful at judging the coherence of statements that contain attributes with a narrow scope of reference compared to attributes with a broad scope of reference. These findings support the hypothesis that AD patients have a semantic memory impairment and suggest a specific deficit processing the network of semantic relations underlying word meaning in semantic memory.

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PubMed1996

Freehand drawing impairments in probable Alzheimer's disease.

We evaluated freehand picture production of familiar objects in patients with probable Alzheimer's disease. The overall recognizability of their drawings was significantly compromised. Error analyses revealed the production of category violations and the frequent inclusion of incorrect features in a picture that were borrowed from semantically related objects, suggesting difficulty distinguishing between items with overlapping features sets in semantic memory. Analyses of individual patient drawing profiles also revealed that some patients are disproportionately compromised in expressing a particular perceptual feature, implicating difficulty at the level of perceptual processing. Regression analyses demonstrated the contribution of limited visual attentional resources. We conclude that impaired freehand drawing in probable Alzheimer's disease is multifactorial in nature.

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PubMed1996

Category-specific difficulty naming with verbs in Alzheimer's disease.

We studied 20 patients with Alzheimer's disease (AD) on a picture-naming task consisting of frequency-matched pairs of nouns and verbs that were homophonic and homographic (e.g., paint). Intragroup comparisons revealed that verb naming is significantly more difficult for patients with AD than noun naming. An error analysis demonstrated that patients with AD produce significantly more semantic and descriptive errors for verbs than nouns. We correlated verb naming and noun naming with measures of grammatical comprehension, lexical retrieval, and visuoperceptual processing, but there were no selective effects for verbs compared with nouns. Differences in the mental representation of concepts underlying verbs and nouns may account, in part, for the relative difficulty naming with verbs in AD.

Aged↗
PubMed1996

Language comprehension profiles in Alzheimer's disease, multi-infarct dementia, and frontotemporal degeneration.

We assessed language functioning in 116 age-, education-, and severity-matched patients with the clinical diagnosis of Alzheimer's disease (AD), multi-infarct dementia (MID) due to small-vessel ischemic disease, or a frontotemporal form of degeneration (FD). Assessments of comprehension revealed that patients with AD are significantly impaired in their judgments of single word and picture meaning, whereas patients with FD had sentence comprehension difficulty due to impaired processing of grammatical phrase structure. Patients with MID did not differ from control subjects in their comprehension performance. Traditional aphasiologic measures did not distinguish between AD, MID, and FD. Selective patterns of comprehension difficulty in patients with different forms of dementia emphasize that language deficits cannot be explained entirely by the compromised memory associated with a progressive neurodegenerative illness.

Aged↗