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Biomedical subjects

G J McDougall

Publications and source records attributed to G J McDougall.

At least 19 recordsLinked to original sources
PubMed2005

Anthocyanins from red wine--their stability under simulated gastrointestinal digestion.

The stability of anthocyanins from red wine was assessed using an in vitro digestion system that simulated the physiochemical changes that occur in the upper gastrointestinal tract. Anthocyanins in red wine were stable to gastric conditions whereas there was a small loss in total phenol content. After pancreatic digestion, the total anthocyanins were very poorly recovered compared to the bulk phenols in the IN sample, which was previously described as the "serum-available" fraction, and the majority of the anthocyanins and phenols were recovered in the OUT fraction, previously described as the "colon-available" fraction. Removing alcohol from the wine samples prior to the procedure did not markedly affect this pattern. The composition of anthocyanins in the post gastric, IN and OUT samples was analysed using liquid chromatography mass-spectrometry. The red wine used contained over 20 identifiable anthocyanins of which the main components were 3-O-glucosides of malvidin, peonidin, petundin, delphidin and cyanidin. Coumaroylated-glucoside derivatives of malvidin, petundin, peonidin, and delphinidin were observed and acetylated glucosides of peonidin, petundin and malvidin were also identified. Anthocyanins with modified aglycones similar to vitisin A derivatives of delphinidin, peonidin, petunidin and malvidin were also identified. After the in vitro digestion procedure, only five anthocyanins could be detected in the IN (serum-available) and the OUT (colon-available) fractions, which were confirmed as malvidin-3-O-glucoside and the vitisin A adducts of malvidin-3-O-glucoside, malvidin-3-O-acetylglucoside, malvidin-3-O-coumaroylglucoside and peonidin-3-O-glucoside. Malvidin-3-O-glucoside was recovered at 0.2% in the IN fraction and 0.9% in the OUT fraction. However, the vitisin derivatives were much more stable to pancreatic digestion. Assuming that the vitisin A derivatives display similar biological properties to their parent anthocyanins, their enhanced gastrointestinal stability could lead to enhanced bioavailability and bio-effectiveness in vivo.

Anthocyanins↗
PubMed2001

Cell-wall proteins from Sitka spruce xylem are selectively insolubilised during formation of dehydrogenation polymers of coniferyl alcohol.

Extracts from the lignifying xylem of Sitka spruce that were enriched in cell-wall-associated glycoproteins contained peroxidase and oxidase activity and readily formed lignin-like water-insoluble dehydrogenation polymers (DHPs) from coniferyl alcohol (CA) when supplied with H2O2. During the formation of DHPs, the abundance of a number of polypeptides in the extracts was diminished. However, these polypeptides were also diminished in control reactions that contained H2O2 but lacked CA. Polypeptides could be recovered from the DHPs by heating in SDS-PAGE sample buffer but no insolubilised polypeptides could be recovered from the + H2O2 reactions. Although most of the DHP-bound polypeptides were easily removed by pre-washing the DHPs, two polypeptides at 125 and 52 kDa remained tightly bound to the DHPs. The abundance of the two DHP-bound polypeptides mirrored the diminution of 120 and 46 kDa polypeptides in the extracts. The N-terminal protein sequences of the 125 and 52 kDa DHP-bound polypeptides were essentially identical to the sequences obtained from the 120 and 46 kDa polypeptides from the extracts, which confirmed that the DHP-bound polypeptides were derived from these soluble polypeptides. The 125-kDa DHP-bound polypeptide yielded an N-terminal protein sequence that was identical to a laccase-type oxidase previously identified in similar extracts from lignifying Sitka xylem. The N-terminal protein sequence of the 46-kDa polypeptide was homologous with a subset of plant peroxidases. The DHPs had tightly bound peroxidase and oxidase activity, which suggested that these polypeptides were active in their insolubilised state. The mechanism and selectivity of insolubilisation of these enzymes is discussed.

Amino Acid Sequence↗
PubMed2001

Recruiting African Americans into research on cognitive aging.

A total of 218 adults with an average age of seventy-eight years participated in a study of memory performance in community elders. A computer-generated random zip code list of adults > or = 70 years of age was purchased and a four-phase telephone-screening plan was adopted. During the second year, the sampling plan had to be changed, with a convenience-sampling plan being adopted to recruit adequate numbers of African-American subjects. Fifty-seven percent of the African-American subjects (N = 55) and 68% of the White subjects (N = 83) were recruited from random sampling methods. As compared to the random sample, the convenience sample was significantly older (80 vs 76), had more depression (12 vs 9), had lower physical functioning (46 vs 65), and less vitality (48 vs 60). On meta-memory, the convenience sample scored higher than the random sample on achievement (3.84 vs 3.69), and lower on task (3.75 vs 3.85). The convenience sample scored significantly lower than the random sample on memory performance (15 vs 18), and memory self-efficacy (26 vs 33). More research is needed to document normative measures for cognitive function and to facilitate accurate comparisons between African-American elderly and other elderly.

Black or African American↗
PubMed2000

Memory improvement in assisted living elders.

Part of the Cognitive Behavioral Model of Everyday Memory (CBMEM), an eight session cognitive enhancement program, entitled "Memories, Memories, Can We Improve Ours?" was tested with older adults living in an assisted living facility in the midwest. The aims of this quasi-experimental study were: to improve everyday memory, memory self-efficacy, and meta-memory. A total of 19 older adults (14 female, 5 male) with an average age of 83 years participated. For the pretest there were 16 individuals in the experimental group. The experimental group was post-tested one week after completing the intervention. At posttest memory self-efficacy scores significantly increased in the experimental group (M1 = 52.13, M2 = 68.50, where M1 represents pretest and M2 represents posttest). Total memory performance scores were not significantly different at posttest; however the prospective memory items of asking for an appointment (M1 = .56, M2 = 1.25), asking for a belonging (M1 = .62, M2 = .88), and delivering a message (M1 = 1.00, M2 = 1.19) significantly improved.

Activities of Daily Living↗
PubMed2000

Oxidase activity in lignifying xylem of a taxonomically diverse range of trees: identification of a conifer laccase.

In a diverse taxonomic range of tree species, including representative species of ancient families of angiosperms (Magnolia x soulangiana Soul.-Bod.) and gymnosperms (Ginkgo biloba L.), oxidase activity was associated with cell walls of developing xylem and was enriched in extracts of cell wall-associated glycoproteins. In all species where oxidase activity was detected histochemically, it was expressed in cell walls of lignifying, differentiating xylem cells and was absent from old wood, cambium and phloem, suggesting that oxidases have a conservative role in lignification of tree xylem. An oxidase from the developing xylem of Picea sitchensis (Bong) Carr. (Sitka spruce) was partially purified by a combination of lectin affinity and immobilized metal ion affinity chromatography. A portion of the total oxidase activity had high affinity for immobilized zinc ions and this feature allowed it to be separated from the bulk of oxidase activity. Two polypeptides that could have been responsible for the bound oxidase activity were enriched by this procedure. The smaller polypeptide of Mr approximately 73 kDa yielded an N-terminal amino-acid sequence that was homologous to laccase-like polyphenol oxidases (E.C. 1.10.3.2) from loblolly pine (Pinus taeda L.), poplar (Populus euramericana (Dode) Guinier) and Arabidopsis. The larger polypeptide (Mr approximately 77 kDa) yielded an N-terminal amino-acid sequence that was homologous with a range of plant subtilisin-like serine proteinases. The roles of oxidase and proteinase activities in developing xylem are discussed.

Cycadopsida↗
PubMed2000

A comparison of proteins from the developing xylem of compression and non-compression wood of branches of sitka spruce (Picea sitchensis) reveals a differentially expressed laccase.

Soluble and cell wall-associated proteins were extracted from the developing xylem of the compression and non-compression sides of branches of Sitka spruce (Picea sitchensis (Bong) Carr.) by an identical procedure. Equal amounts of proteins were separated by SDS-PAGE, and polypeptides were identified that were more abundant in soluble and cell wall-associated extracts from the developing xylem of either compression or non-compression wood. Two polypeptides (at apparent M(r)s of 48 kDa and 120 kDa) that were more abundant in cell wall-associated extracts of the developing xylem of the compression tissues were selected for amino-terminal protein sequencing. The 48 kDa polypeptide yielded an amino-terminal sequence that had no homology with known protein, gene or EST database sequences. The amino-terminal sequence of the 120 kDa polypeptide was homologous to a number of laccase-type polyphenol oxidases (EC 1.10.3.2) thought to be involved in lignin biosynthesis in trees. Using non-denaturing SDS-PAGE, the 120 kDa laccase was confirmed as a major oxidase activity in extracts of lignifying compression xylem but it was barely detectable in the non-compression extracts where an 85 kDa oxidase was the predominant activity. The differential expression of oxidases in compression and non-compression xylem is discussed.

Amino Acid Sequence↗
PubMed1999

Cognitive interventions among older adults.

This chapter reviews psychoeducational and/or psychosocial interventions designed to improve cognitive function in adults without cognitive impairment. Included are sections on (a) meta-analyses and other reviews; (b) cognitive aging and cognitive improvement; (c) memory training; (d) depression and memory improvement; (e) self-efficacy and aging memory; (f) maintenance of gains and subject retention; (g) comprehensive memory improvement program; and (h) future research. Several aspects of memory training now known to influence outcomes, i.e., memory performance, need to be considered in future studies. First, follow-up instruction (booster sessions) facilitates the use of these newly learned memory strategies in elders' everyday lives. Second, elders' memory self-efficacy (beliefs and confidence) impacts performance. Third, the inclusion of subjective measures in memory training is recommended. Fourth, greater emphasis needs to be placed on the modification of participants' attitudes toward aging-related memory loss. Fifth, designs must emphasize the long-term outcomes of the memory training. Sixth, establishing a relationship between a memory intervention and functional ability (IADLs) is the next step in assisting older adults to remain independent. If early failure in cognitive ability can be improved through intervention, perhaps early decline in functional independence and the need for formal services, e.g., nursing home placement, can be delayed.

Aged↗
PubMed1999

Memory awareness among Japanese nursing facility residents.

One hundred and seventeen elderly residents of seven geriatric health facilities located in Tokyo participated in this study. The Mini-Mental State, Metamemory in Adulthood, Geriatric Depression Health Scale and demographic questionnaires were used in face-to-face interviews. The subjects were 32 males and 85 females, with a mean age of 83.08 years. Depression was found to be a key factor for explaining metamemory. Depression accounted for 17% of the variance in capacity and 23% in change. There were no differences between the mild cognitive impairment group and the cognitively intact group on achievement, capacity, change, locus and strategy subscales. When depression was considered as a moderating factor, a difference arose between two cognitive levels. History of stroke was not related to metamemory in this study; however, future studies should emphasize memory awareness in brain injury residents since 41% of the sample had a history of CVA.

Aged↗
PubMed1998

Memory awareness in nursing home residents.

BACKGROUND: Health care providers often believe that individuals with cognitive disturbance are unaware of their deficits. The term unawareness was first used to describe hemiplegia following right hemisphere stroke but has since been applied to unawareness of any neurological or neuropsychological deficit. Clinicians usually rely on their subjective observations to evaluate the patient's awareness of deficits, and few investigators have systematically evaluated this important clinical phenomenon. OBJECTIVE: The aim of this study was to compare cognition, depression, health, and metamemory (capacity, change, locus, and strategy) in four groups of nursing home residents: the cognitively impaired (29%), depressed (18%), mixed with both cognitive impairment and depression (32%), and controls (21%). METHODS: Subjects were 106 residents of six nursing homes between the ages of 79 and 87 with a mean age of 84.18 (SD = 10.01) years, and an average of six comorbid medical conditions. Cognitive function was measured with the Mini Mental State (MMSE); depression with the Geriatric Depression, and metamemory with the Metamemory in Adulthood scales. Anyone scoring <15 on the MMSE was excluded. Subjects included 31 with cognitive impairment, 19 depressed, 34 mixed, and 22 controls. RESULTS: In this sample, 61% were cognitively impaired; however, only 12 had a diagnosis in their records indicating cognitive disturbance. Forty-three percent were depressed. The correlations between depression and capacity (r = -0. 38), change (r = -0.50), and locus (r = -0.25) were significant. The controls were significantly younger than the cognitively impaired group. The controls also had higher perceived health status scores than either the cognitively impaired or the depressed group. However, the mixed group's perceived health status scores were significantly higher than the depressed group's scores. CONCLUSION: The metamemory components of capacity and change were able to differentiate the cognitively impaired from the mixed group. Information on the etiology of cognitive impairment was not available since residents' charts in the six nursing homes provided inadequate documentation and incomplete diagnostic histories. Therefore, quantitative methods for examining memory awareness and the affective state of elderly patients is important for clinicians in order to make informed treatment decisions.

Aged↗
PubMed1998

Gender differences in coping and control with memory aging.

This secondary analysis of data from a large study of memory perceptions among the elderly examined gender differences in control, coping, health, and metamemory and explored the influence of these factors on anxiety and depression in the elderly. Adults 55 years of age and older, 128 female and 41 males, were recruited from continuing education programs in two Southern states. Females were older than males and reported that their memories were better overall than males. There were no differences between the groups in depression, health, or memory control variables. Females had significantly greater state anxiety than males but no differences were seen in domain-specific memory anxiety or other metamemory domains. Females scored higher than males on help-seeking, existential growth, religiosity, and total coping strategies. In the two regression models the set of study variables predicted 79% of the variance in depression and 15% of the variance in memory anxiety. The addition of perceived health status to each model substantially changed each of their predictive values.

Adaptation, Psychological↗
PubMed1997

Dual diagnosis in elders discharged from a psychiatric hospital.

Recent evidence indicates persons 60 years and over experience significant alcohol and substance abuse problems. Since a combination of alcoholism and depression is likely to increase the relative rsk of suicide, it is important to examine the prevalence of dual diagnosis in older adults. The purpose of this study is to examine the prevalence and correlates of dual diagnosis in older psychiatric inpatient populations and compare our results with findings from studies of younger hospitalized dually diagnosed patients. A retrospective chart audit was performed on 101 elders who were discharged from three psychiatric hospitals. Clinical variables that were examined included length of hospital stay, psychiatric and medical diagnoses, medications and history of suicidal ideation or intent. The leading psychiatric disorder diagnosis for our sample of hospitalized psychiatric elders was depression. Over one-third (37.6%) had a substance abuse disorder in addition to a psychiatric disorder, and almost three-fourths (71%) of this 'dual diagnosis' group abused alcohol and 29% abused both alcohol and other substances. In addition, significantly more elders in the "dual diagnosis' group (17.7%) than in the group with only a mental disorder diagnosis (3.3%) made a suicide attempt prior to admission to the hospital. Because, affective disorders in conjunction with alcohol abuse are the most frequently found disorders in completed suicides, our findings have important relevance for the advocating of routine use of diagnostic assessment and screening for both substance abuse and mental disorders in this population.

Aged↗
PubMed1995

A critical review of research on cognitive function/impairment in older adults.

Research on aspects of cognitive function and impairment in older adults is critically reviewed with the aim of evaluation and synthesis. The body of research on cognitive aging, mostly atheoretical, has not been placed within the larger context of cognitive sciences. Methodological concerns and lack of a unifying framework inhibit integration of previous studies and the development of a cohesive body of knowledge. Therefore, one paradigm of adult cognition, information processing, is recommended to further advance nursing theory and research.

Aged↗
PubMed1995

Memory strategies used by cognitively intact and cognitively impaired older adults.

This study examined the influence of depression and health on the use of memory strategies of cognitively impaired (n = 55) and cognitively intact (n = 169) older adults. The intact group used memory strategies more often than the impaired group and were more likely to use external strategies such as diaries, notes, and lists, instead of internal strategies such as elaboration and rehearsal. The impaired group used the internal strategies such as elaboration and rehearsal. The impaired group used the internal strategy effort more often. There was no difference in perception of memory capacity between groups. Depression had a negative influence on perceptions of capacity and change in both groups.

Adaptation, Psychological↗
PubMed1991

Purification and analysis of growth-regulating xyloglucan-derived oligosaccharides by high-pressure liquid chromatography.

The retention times of 10 oligosaccharides, generated from the xyloglucans of Rosa and Tropaeolum by the action of Trichoderma cellulase, and of 17 related carbohydrates, in h.p.l.c. on an amino-substituted silica (Amino-Spheri-5) depended largely on the number of hydroxyl groups per molecule, whereas h.p.l.c. on a pellicular anion-exchange resin (CarboPac PA1) was strongly influenced by the nature of the sugar residues present, especially L-fucose, and by their linkages. The major nonasaccharide (XG9, D-Glc4-D-Xyl3-D-Gal-L-Fuc) obtained from Rosa xyloglucan, after purification on Amino-Spheri-5, retained biological activity as an inhibitor of auxin-induced growth in a Pisum stem-segment bioassay. H.p.l.c. on Amino-Spheri-5 was used to monitor the action of "Driselase" in stripping the non-reducing terminal alpha-D-Xylp-(1----6)-beta-D-Glcp units from XG9 to yield a pentasaccharide (XG5, D-Glc2-D-Xyl-D-Gal-L-Fuc).

Biological Assay↗
PubMed1990

Xyloglucan oligosaccharides promote growth and activate cellulase: evidence for a role of cellulase in cell expansion.

Oligosaccharides produced by the action of fungal cellulase on xyloglucans promoted the elongation of etiolated pea (Pisum sativum L.) stem segments in a straight-growth bioassay designed for the determination of auxins. The oligosaccharides were most active at about 1 micromolar. We tested the relative growth-promoting activities of four HPLC-purified oligosaccharides which shared a common glucose(4). xylose(3) (XG7) core. The substituted oligosaccharides XG8 (glucose(4). xylose(3). galactose) and XG9n (glucose(4). xylose(3). galactose(2)) were more effective than XG7 itself and XG9 (glucose(4). xylose(3). galactose. fucose). The same oligosaccharides also promoted the degradation, assayed viscometrically, of xyloglucan by an acidic cellulase from bean (Phaseolus vulgaris L.) leaves. The oligosaccharides were highly active at 10(-4) molar, causing up to a fourfold increase in activity, but the effect was still detectable at 1 micromolar. Those oligosaccharides (XG8 and XG9n) which best promoted growth, stimulated cellulase activity to the greatest extent. The oligosaccharides did not stimulate the action of the cellulase in an assay based on the conversion of [(3)H]xyloglucan to ethanol-soluble fragments. This suggest that the oligosaccharides enhanced the midchain hydrolysis of xyloglucan molecules (which would rapidly reduce the viscosity of the solution), at the expense of cleavage near the termini (which would yield ethanol-soluble products). We suggest that the promotion of midchain xyloglucan cleavage, by loosening the primary cell wall matrix, explains the promotion of growth by the oligosaccharides.

Journal Article↗