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Biomedical subjects

K Bell

Publications and source records attributed to K Bell.

At least 37 records · Page 2Linked to original sources
PubMed2000

Olfactory deficits in patients with mild cognitive impairment predict Alzheimer's disease at follow-up.

OBJECTIVE: This study evaluated the predictive utility of olfactory identification deficits in patients with mild cognitive impairment for follow-up diagnosis of probable Alzheimer's disease. METHOD: Ninety outpatients with mild cognitive impairment were examined at 6-month intervals. Matched healthy comparison subjects (N=45) were examined annually. The University of Pennsylvania Smell Identification Test was given at baseline. RESULTS: Olfaction scores were lower in patients with mild cognitive impairment than in healthy comparison subjects. Seventy-seven patients were followed up; 19 were diagnosed with Alzheimer's disease by 2 years. Patients with low olfaction scores (< or =34 of 40), and patients with low olfaction scores who reported no subjective problems smelling, were more likely to develop Alzheimer's disease than other patients. In a Cox proportional hazards model adjusted for age, sex, modified Mini-Mental State score, and education, low olfaction scores did not predict time until development of Alzheimer's disease, but low olfaction scores accompanied by lack of awareness of olfactory deficits predicted time to development of Alzheimer's disease. This effect remained when attention or memory measures replaced modified Mini-Mental State score in the model. In patients with high Mini-Mental State scores (> or =27 of 30), low olfaction with lack of awareness remained a significant predictor of Alzheimer's disease. Olfaction scores of 30-35 showed moderate to strong sensitivity and specificity for diagnosis of Alzheimer's disease at follow-up. CONCLUSIONS: In patients with mild cognitive impairment, olfactory identification deficits, particularly with lack of awareness of olfactory deficits, may have clinical utility as an early diagnostic marker for Alzheimer's disease.

Aged↗
PubMed1999

Low-density lipoprotein cholesterol and the risk of dementia with stroke.

CONTEXT: Next to Alzheimer disease, vascular dementia is the second most common form of dementia in the elderly, yet few specific risk factors have been identified. OBJECTIVE: To investigate the relationship of plasma lipids and lipoproteins to dementia with stroke. DESIGN AND SETTING: Prospective longitudinal community-based study over a 7-year period (1991-1998). PARTICIPANTS: A total of 1111 nondemented participants (mean [SD] age, 75.0 [5.9] years) were followed up for an average of 2.1 years (range, 1-7.8 years). MAIN OUTCOME MEASURE: Incident dementia with stroke according to standardized criteria, by baseline levels of total plasma cholesterol and triglycerides, low-density lipoprotein (LDL) cholesterol, LDL levels corrected for lipoprotein(a), high-density lipoprotein cholesterol, lipoprotein(a), and apolipoprotein E genotype. RESULTS: Two hundred eighty-six (25.7%) of the 1111 subjects developed dementia during follow-up; 61 (21.3%) were classified as having dementia with stroke and 225 (78.7%) as having probable Alzheimer disease. Levels of LDL cholesterol were significantly associated with an increased risk of dementia with stroke. Compared with the lowest quartile, the highest quartile of LDL cholesterol was associated with an approximately 3-fold increase in risk of dementia with stroke, adjusting for vascular risk factors and demographic variables (relative risk [RR], 3.1; 95% confidence interval [CI], 1.5-6.1). Levels of LDL corrected for lipoprotein(a) were an even stronger predictor of dementia with stroke in the adjusted multivariate analysis. Compared with the lowest quartile, the RR of dementia with stroke for the highest quartile of lipoprotein(a)-corrected LDL cholesterol was 4.1 (95% CI, 1.8-9.6) after adjusting for vascular factors and demographic variables. Lipid or lipoprotein levels were not associated with the development of Alzheimer disease in our cohort. CONCLUSIONS: Elevated levels of LDL cholesterol were associated with the risk of dementia with stroke in elderly patients. Further study is needed to determine whether treatment of elevated LDL cholesterol levels will reduce the risk of dementia with stroke.

Aged↗
PubMed1999

Assessment of cognition in advanced AD: the test for severe impairment.

The Test for Severe Impairment (TSI) was compared with the Mini-Mental State Examination (MMSE) and a modified MMSE (mMMSE) in a multisite, longitudinal study of AD. The TSI correlated highly with the MMSE (r = 0.83) and the mMMSE (r = 0.82), but was not redundant. There was a wide range of scores on the TSI among those scoring in the severely impaired range on the MMSE and mMMSE. The slope of cognitive change over time detected by the TSI was greater than that revealed by the MMSE or the mMMSE. Performance on the TSI was a significant predictor of survival. The TSI is a valid measure that is sensitive to cognitive change over time in severely demented patients with AD.

Aged↗
PubMed1999

Plasma amyloid beta-peptide 1-42 and incipient Alzheimer's disease.

Mutations in the amyloid precursor protein and presenilin 1 and 2 genes result in elevated plasma levels of the amyloid beta-peptide species terminating at amino acid residue 42 (A beta1-42). In a longitudinal study of unrelated elderly individuals, those who subsequently developed Alzheimer's disease had higher plasma levels of A beta1-42 at entry than did those who remained free of dementia. The results indicate that elevated plasma levels of the released A beta peptide A beta1-42 may be detected several years before the onset of symptoms, supporting that extracellular A beta1-42 plays an important role in the pathogenesis of late-onset Alzheimer's disease.

Age of Onset↗
PubMed1999

Cerebral tuberculomas in Northern Ireland.

Two children presenting with very different clinical pictures were both found to have intracranial tuberculomas. This condition, although rare in developed countries, should be suspected in any child with enhancing cerebral lesions or cranial computed tomography.

Antitubercular Agents↗
PubMed1999

Effect of literacy on neuropsychological test performance in nondemented, education-matched elders.

The current investigation compared neuropsychological test performance among nondemented literate and illiterate elders. The sample included participants in an epidemiological study of normal aging and dementia in the Northern Manhattan community. All participants were diagnosed as nondemented by a neurologist, and did not have history of Parkinson's disease, stroke, or head injury. Literacy level was determined by self-report. MANOVAs revealed a significant overall effect for literacy status (literate vs. illiterate) on neuropsychological test performance when groups were matched on years of education. The overall effect of literacy status remained significant after restricting the analyses to elders with no formal education, and after controlling for the effects of language of test administration. Specifically, illiterates obtained lower scores on measures of naming, comprehension, verbal abstraction, orientation, and figure matching and recognition. However tests of verbal list delayed recall, nonverbal abstraction, and category fluency were unaffected by literacy status, suggesting that these measures can be used to accurately detect cognitive decline among illiterate elders in this sample. Differences in organization of visuospatial information, lack of previous exposure to stimuli, and difficulties with interpretation of the logical functions of language are possible factors that contribute to our findings.

Aged↗
PubMed1999

Report of the International Equine Gene Mapping Workshop: male linkage map.

The goal of the First International Equine Gene Mapping Workshop, held in 1995, was the construction of a low density, male linkage map for the horse. For this purpose, the International Horse Reference Family Panel (IHRFP) was established, consisting of 12 paternal half-sib families with 448 half-sib offspring provided by 10 laboratories. Blood samples were collected and DNA extracted in each laboratory and sent to the Lexington laboratory (KY, USA) for dispatch in aliquots to 14 typing laboratories. In total, 161 markers (144 microsatellites, seven blood groups and 10 proteins) were tested for all families for which the sire was heterozygous. Genealogies and typing data were sent for analysis to the INRA laboratory (Jouy-en-Josas, France) according to a specific format and entered into a database with input verification and output processes. Linkage analysis was performed with the CRIMAP program. Significant linkage was detected for 124 loci, of which 95 were unambiguously ordered using a multipoint analysis with an average spacing of 14.2 CM. These loci were distributed among 29 linkage groups. A more comprehensive analysis including synteny group data and FISH data suggested that 26 autosomes out of 31 are covered. The complete map spans 936 CM.

Animals↗
PubMed1999

Single nucleotide polymorphisms in the equine transferrin gene.

Single nucleotide polymorphisms (SNPs) in exons 13, 15 and 16 of equine transferrin for common, rare and mutant variants were investigated. Compared with previous work a further 13 SNPs have been identified, allowing for the two previously identified clades to be subdivided into 11 groups. A combination of one or more of eight SNPs can be used to classify the equine variants into these 11 groups, since most are co-inherited. Putative sites of glycosylation in exons 13 and 16 showed no polymorphism, suggesting that presence or absence of sugar moieties does not lead to electrophoretic variation between the variants. Using the 26 SNPs currently identified in transferrin it is still not possible to differentiate variants F1 from F2, or D from H2, which represent 75% of the variants occurring in Thoroughbred equine population. This suggests that further SNPs exist in equine transferrin. The significance of the high level of variation in exon 15 is discussed.

Animals↗
PubMed1999

Functional significance of mild cognitive impairment in elderly patients without a dementia diagnosis.

The authors investigated differences in functional ability among three groups of subjects who were not diagnosed with dementia: normal control (NC) subjects (n=35); Clinical Dementia Rating Scale (CDRS) score of 0 (minimal impairment; n=26); and CDRS 0. 5 (questionable dementia; n=42). CDRS 0 and 0. 5 patients reported significantly poorer functioning than NCs in household and other activities, but CDRS 0 and CDRS 0. 5 groups did not differ in self-reported functioning. It is likely that CDRS 0. 5 patients overestimated their functional abilities. Correlations between self- and informant reports of functional status were significantly lower in the CDRS 0. 5 group than in the CDRS 0 group, an important finding for clinical management because patients with questionable dementia may actually be more impaired than they admit. Informants' reports or standardized performance-based assessment should be considered in the clinical evaluation of such patients.

Activities of Daily Living↗
PubMed1999

Free fatty acid-induced insulin resistance is associated with activation of protein kinase C theta and alterations in the insulin signaling cascade.

To examine the mechanism by which free fatty acids (FFAs) induce insulin resistance in vivo, awake chronically catheterized rats underwent a hyperinsulinemic-euglycemic clamp with or without a 5-h preinfusion of lipid/heparin to raise plasma FFA concentrations. Increased plasma FFAs resulted in insulin resistance as reflected by a approximately 35% reduction in the glucose infusion rate (P < 0.05 vs. control). The insulin resistance was associated with a 40-50% reduction in 13C nuclear magnetic resonance (NMR)-determined rates of muscle glycogen synthesis (P < 0.01 vs. control) and muscle glucose oxidation (P < 0.01 vs. control), which in turn could be attributed to a approximately 25% reduction in glucose transport activity as assessed by 2-[1,2-3H]deoxyglucose uptake in vivo (P < 0.05 vs. control). This lipid-induced decrease in insulin-stimulated muscle glucose metabolism was associated with 1) a approximately 50% reduction in insulin-stimulated insulin receptor substrate (IRS)-1-associated phosphatidylinositol (PI) 3-kinase activity (P < 0.05 vs. control), 2) a blunting in insulin-stimulated IRS-1 tyrosine phosphorylation (P < 0.05, lipid-infused versus glycerol-infused), and 3) a four-fold increase in membrane-bound, or active, protein kinase C (PKC) theta (P < 0.05 vs. control). We conclude that acute elevations of plasma FFA levels for 5 h induce skeletal muscle insulin resistance in vivo via a reduction in insulin-stimulated muscle glycogen synthesis and glucose oxidation that can be attributed to reduced glucose transport activity. These changes are associated with abnormalities in the insulin signaling cascade and may be mediated by FFA activation of PKC theta.

Animals↗
PubMed1998

The APOE-epsilon4 allele and the risk of Alzheimer disease among African Americans, whites, and Hispanics.

CONTEXT: Although the association between Alzheimer disease (AD) and the apolipoprotein E epsilon4 (APOE-epsilon4) allele has been confirmed worldwide, it appears to be inconsistent among African Americans, Hispanics, and Nigerians. OBJECTIVE: To investigate the association between the APOE-epsilon4 allele and AD in elderly African Americans, Hispanics, and whites. DESIGN: Prospective, population-based, longitudinal study over a 5-year period (1991-1996). SETTING: The Washington Heights-Inwood community of New York City. PARTICIPANTS: A total of 1079 Medicare recipients without AD or a related disorder at baseline. MAIN OUTCOME MEASURES: Risk of clinically diagnosed AD in the 3 ethnic groups and among individuals with and without an APOE-epsilon4 allele. RESULTS: Compared with individuals with the APOE-epsilon3/epsilon3 genotype, the relative risk (RR) of AD associated with 1 or more copies of the APOE-epsilon4 allele was significantly increased among whites (RR, 2.5; 95% confidence interval [CI], 1.1-6.4), but not among African Americans (RR, 1.0; 95% CI, 0.6-1.6) or Hispanics (RR, 1.1; 95% CI, 0.7-1.6). In the absence of the APOE-epsilon4 allele, the cumulative risks of AD to age 90 years, adjusted for education and sex, were 4 times higher for African Americans (RR, 4.4; 95% CI, 2.3-8.6) and 2 times higher for Hispanics (RR, 2.3; 95% CI, 1.2-4.3) than for whites. In the presence of an APOE-epsilon4 allele, the cumulative risk of AD to age 90 years was similar for individuals in all 3 ethnic groups. CONCLUSION: The presence of an APOE-epsilon4 allele is a determinant of AD risk in whites, but African Americans and Hispanics have an increased frequency of AD regardless of their APOE genotype. These results suggest that other genes or risk factors may contribute to the increased risk of AD in African Americans and Hispanics.

Aged↗
PubMed1998

In vivo percutaneous absorption of boric acid, borax, and disodium octaborate tetrahydrate in humans compared to in vitro absorption in human skin from infinite and finite doses.

Literature from the first half of this century report concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10%, in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percentage dose, with flux and permeability constant (Kp) calculated at 0.009 microgram/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percentage of dose, with flux and Kp calculated at 0.009 microgram/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percentage, with flux and Kp calculated at 0.01 microgram/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. In vitro human skin percentage of doses of boric acid absorbed were 1.2 for a 0.05% solution, 0.28 for a 0.5% solution, and 0.70 for a 5.0% solution. These absorption amounts translated into flux values of, respectively, 0.25, 0.58, and 14.58 micrograms/cm2/h and permeability constants (Kp) of 5.0 x 10(-4), 1.2 x 10(-4), and 2.9 x 10(-4) cm/h for the 0.05, 0.5, and 5.0% solutions. The above in vitro doses were at infinite, 1000 microliters/cm2 volume. At 2 microliters/cm2 (the in vivo dosing volume), flux decreased some 200-fold to 0.07 microgram/cm2/h and Kp of 1.4 x 10(-6) cm/h, while percentage of dose absorbed was 1.75%. Borax dosed at 5.0%/1000 microliters/cm2 had 0.41% dose absorbed, flux at 8.5 micrograms/cm2/h, and Kp was 1.7 x 10(-4) cm/h. Disodium octaborate tetrahydrate (DOT) dosed at 10%/1000 microliters/cm2 was 0.19% dose absorbed, flux at 7.9 micrograms/cm2/h, and Kp was 0.8 x 10(-4) cm/h. These in vitro results from infinite doses (1000 microliters/cm2) were 1000-fold greater than those obtained in the companion in vivo study. The results from the finite (2 microliters/cm2) dosing were closer (10-fold difference) to the in vivo results. General application of infinite dose percutaneous absorption values for risk assessment is questioned by these results. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin, is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

Adult↗
PubMed1998

In vivo percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in humans: a summary.

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included inductively coupled plasma-mass spectrometry, which now allows quantitation of percutaneous absorption of 10B in 10B-enriched boric acid, borax, and disodium octaborate tetrahydrate (DOT) in biological matrices. This made it possible, in the presence of comparatively large natural dietary boron intakes for the in vivo segment of this study, to quantify the boron passing through skin. Human volunteers were dosed with 10B-enriched boric acid, 5.0%, borax, 5.0%, or disodium octaborate tetrahydrate, 10% in aqueous solutions. Urinalysis, for boron and changes in boron isotope ratios, was used to measure absorption. Boric acid in vivo percutaneous absorption was 0.226 (SD = 0.125) mean percent dose, with flux and permeability constant (Kp) calculated at 0.009 microg/cm2/h and 1.9 x 10(-7) cm/h, respectively. Borax absorption was 0.210 (SD = 0.194) mean percent dose, with flux and Kp calculated at 0.009 microg/cm2/h and 1.8 x 10(-7) cm/h, respectively. DOT absorption was 0.122 (SD = 0.108) mean percent, with flux and Kp calculated at 0.01 microg/cm2/h and 1.0 x 10(-7) cm/h, respectively. Pretreatment with the potential skin irritant 2% sodium lauryl sulfate had no effect on boron skin absorption. These in vivo results show that percutaneous absorption of boron, as boric acid, borax, and disodium octaborate tetrahydrate, through intact human skin is low and is significantly less than the average daily dietary intake. This very low boron skin absorption makes it apparent that, for the borates tested, the use of gloves to prevent systemic uptake is unnecessary. These findings do not apply to abraded or otherwise damaged skin.

Administration, Topical↗