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Biomedical subjects

J D Williamson

Publications and source records attributed to J D Williamson.

At least 37 records · Page 2Linked to original sources
PubMed1998

High body fatness, but not low fat-free mass, predicts disability in older men and women: the Cardiovascular Health Study.

Using data from the Cardiovascular Health Study, we studied the relation between body composition (fat mass and fat-free mass, assessed by bioelectrical impedance) and self-reported, mobility-related disability (difficulty walking or stair climbing) in 2714 women and 2095 men aged 65-100 y. In a cross-sectional analysis at baseline (1989-1990), disability was reported by 26.5% of the women and 16.9% of the men. A positive association was observed between fat mass and disability. The odds ratio for disability in the highest quintile of fat mass was 3.04 (95% CI: 2.18, 4.25) for women and 2.77 (95% CI: 1.82, 4.23) for men compared with those in the lowest quintile. Low fat-free mass was not associated with a higher prevalence of disability. In a longitudinal analysis among persons not reporting disability at baseline, 20.3% of the women and 14.8% of the men reported disability 3 y later. Fat mass at baseline was predictive of disability 3 y later, with odds ratios of 2.83 (95% CI: 1.80, 4.46) for women and 1.72 (95% CI: 1.03, 2.85) for men in the highest quintile of fat. The increased risk was not explained by age, physical activity, chronic disease, or other potential confounders. Low fat-free mass was not predictive of disability. The results showed that high body fatness is an independent predictor of mobility-related disability in older men and women. These findings suggest that high body fatness in old age should be avoided to decrease the risk of disability.

Adipose Tissue↗
PubMed1998

Height, weight, and body fat: assessments of covariation based on visual information or reported correlations.

College students' intuitive judgments about covariations between height, weight, and body fat were assessed in three experiments using responses to a series of propositional statements as the dependent variable. In Exp. 1, judgments were rendered without explicit exposure to a prior database. In Exps. 2 and 3, however, databases were studied prior to these judgments. Remarkable consistencies in judgments of weight and body fat, height and weight as well as of height and body fat were obtained across experiments. At best, there was little evidence that the databases influenced the judged covariations among these variables. Whereas judgments about weight and body fat were unambiguous and consistent with the actual positive correlation between weight and body fat, judgments about height and weight as well as height and body fat were less clearcut. What was clear, however, was that these judgments were highly similar. Implications of these findings from previous research that suggest that presence of a perceived negative correlation between height and body fat are discussed.

Adipose Tissue↗
PubMed1998

Length, weight, and width: covariation assessments based on haptic exploration.

Intuitive judgements about covariations of length, weight, and width were assessed in two experiments using a series of propositional statements. In Exp. 1, only a priori judgements were rendered, whereas in Exp. 2 blindfolded participants physically manipulated and described a series of objects varying on these dimensions before rendering their judgements. Analyses indicated participants judged weight and width as positively correlated, length and weight as uncorrelated and, to some extent, length and width as negatively correlated. If judgements are rendered after the haptic exploration phase, weight and width are (again) judged as positively correlated, and length and weight were still judged as uncorrelated. However, after the database intervention. length and width were judged as positively correlated. Results are discussed relative to research on reasoning about covariation and belief perseveration as well as perceived covariations between height, weight, and body fat.

Adipose Tissue↗
PubMed1997

Subcellular localization of celery mannitol dehydrogenase. A cytosolic metabolic enzyme in nuclei.

Mannitol dehydrogenase (MTD) is the first enzyme in mannitol catabolism in celery (Apium graveolens L. var dulce [Mill] Pers. cv Florida 638). Mannitol is an important photoassimilate, as well as providing plants with resistance to salt and osmotic stress. Previous work has shown that expression of the celery Mtd gene is regulated by many factors, such as hexose sugars, salt and osmotic stress, and salicylic acid. Furthermore, MTD is present in cells of sink organs, phloem cells, and mannitol-grown suspension cultures. Immunogold localization and biochemical analyses presented here demonstrate that celery MTD is localized in the cytosol and nuclei. Although the cellular density of MTD varies among different cell types, densities of nuclear and cytosolic MTD in a given cell are approximately equal. Biochemical analyses of nuclear extracts from mannitol-grown cultured cells confirmed that the nuclear-localized MTD is enzymatically active. The function(s) of nuclear-localized MTD is unknown.

Cell Nucleus↗
PubMed1997

The association of antihypertensive agents with MRI white matter findings and with Modified Mini-Mental State Examination in older adults.

OBJECTIVES: To examine the association of antihypertensive regimen with magnetic resonance imaging (MRI) white matter hyperintensity and with cognitive impairment in older adults. DESIGN: Cross-sectional study. SETTING: The Cardiovascular Health study, an observational prospective cohort study of risk factors for coronary heart disease and stroke in men and women 65 years of age and older. PARTICIPANTS: 1268 men and women with pharmacologically treated hypertension. MEASUREMENTS: Information on medication use, medical history, and health habits was collected at clinic examinations. Participants completed the Modified Mini-Mental State Examination (3MS) and underwent MRI examination. Without clinical information, study neuroradiologists assigned an overall grade of white matter signal intensity on MRI on a scale from 0 (no findings) to 9 (extensive findings). RESULTS: Adjusted mean white matter grade was higher for users of calcium channel blockers (2.59, P = .007) and users of loop diuretics (2.60, P = .015) than for users of beta blockers (2.12). The association was present for both dihydropyridine and non-dihydropyridine calcium channel blockers. Adjusted mean 3MS scores were lower for users of calcium channel blockers (89.6, P < .002), especially dihydropyridines, and users of loop diuretics (89.7, P < .006) than for users of beta blockers (92.3). No statistically significant association could be shown for users of other drug regimens, including thiazides and ACE inhibitors. CONCLUSION: In this study, users of antihypertensive regimens which included calcium channel blockers or loop diuretics had more severe white matter hyperintensity on MRI and worse performance on 3MS than users of beta blockers.

Adrenergic beta-Antagonists↗
PubMed1996

Environmental health and public health: are they compatible?

Since the beginnings of public health were rooted in environmental issues the question posed might seem absurd. However, there is a point because the approaches to the two are slightly different in most countries and increasingly different in the United Kingdom.

Environmental Health↗
PubMed1996

Functional decline in older adults: expanding methods of ascertainment.

BACKGROUND: There is substantial interest in the prevention of physical disability associated with aging. However, little is known about how to screen for declining function at sufficiently early stages to prevent frank disability. This work provides an initial description and assessment of a new self-report method for measuring function in older adults which complements standard methods and may be sensitive to subtler degrees of disablement than currently employed methods. We operationalize the method and demonstrate that it identifies a meaningful number of people as potentially disabled who are not identified by standard methods; also, we evaluate the method's reliability and validity for identifying subtle functional decline relative to existing methods. METHODS: This is a cross-sectional, observational study of a volunteer population of 231 adults 59 years and older, evaluated in a multidisciplinary laboratory. Self-reported difficulty and dependency in each of 27 tasks of daily life were assessed as the measure of disability. Those without difficulty were evaluated for other functional change, by self-report, defined as either: (a) modification of method, or (b) decreased frequency of task performance, when due to health rather than change in social circumstances. Prevalence, test-retest reliability, construct, and criterion validity were evaluated. RESULTS: In a study population in which from 1% to 50% of participants reported difficulty with each of 27 tasks, from 2% to 33% reported modification of task performance while not having difficulty. Few participants reported decreased frequency without modification. Persons with task modifications, particularly in mobility tasks, showed intermediate levels of performance on objectively measured tests and an intermediate number of chronic diseases, compared to those reporting difficulty and those reporting neither difficulty nor modification. CONCLUSIONS: Cross-sectional evidence supports the ability of the proposed method to identify meaningful numbers of people with functional decline who were not identified by standard self-report methods. In some cases, these were individuals with functional losses comparable to those who did report difficulty. In other cases, these may have been individuals with earlier functional loss, perhaps representing a preclinical stage of disability. Prospective evaluation will identify whether this method predicts the onset of difficulty or disability, and whether it predicts decline with sufficient precision to identify at-risk individuals in a clinical setting.

Activities of Daily Living↗
PubMed1996

Immunolocalization of mannitol dehydrogenase in celery plants and cells.

Immunolocalization of mannitol dehydrogenase (MTD) in celery (Apium graveolens L.) suspension cells and plants showed that MTD is a cytoplasmic enzyme. MTD was found in the meristems of celery root apices, in young expanding leaves, in the vascular cambium, and in the phloem, including sieve-element/companion cell complexes, parenchyma, and in the exuding phloem sap of cut petioles. Suspension cells that were grown in medium with mannitol as the sole carbon source showed a high anti-MTD cross-reaction in the cytoplasm, whereas cells that were grown in sucrose-containing medium showed little or no cross-reaction. Gel-blot analysis of proteins from vascular and nonvascular tissues of mature celery petioles showed a strong anti-MTD sera cross-reactive band, corresponding to the 40-kD molecular mass of MTD in vascular extracts, but no cross-reactive bands in nonvascular extracts. The distribution pattern of MTD within celery plants and in cell cultures that were grown on different carbon sources is consistent with the hypothesis that the Mtd gene may be regulated by sugar repression. Additionally, a developmental component may regulate the distribution of MTD within celery plants.

Animals↗
PubMed1996

Characterization of older adults who attribute functional decrements to "old age".

OBJECTIVE: Understanding the contributors to physical disability in older adults is an important component of the national health objective of expanding disability-free life by the year 2000. The purpose of this study was to determine the frequency with which older adults attribute their difficulty performing a number of common daily tasks to "old age" and to identify specific conditions and diseases associated with this attribution. Finally we sought to determine the characteristics that might differentiate persons able to attribute their disability to specific conditions from those who cite old age as the etiology of their disability. DESIGN: A cross-sectional, observational, study. SETTING: The Johns Hopkins Functional Status Laboratory. PARTICIPANTS: Two hundred thirty community-dwelling volunteers 60 years of age and older who could stand unassisted for > or = 1 minute and who were without cognitive impairment. MEASUREMENTS: A 1-day evaluation included physical performance evaluations, both performance-based and self-reported function for 27 tasks, and self-report of physician-diagnosed diseases. Those with difficulty in a task and those who denied difficulty but had changed the method of task performance (modification) because of an underlying health or physical condition were identified and asked to name the cause of their difficulty or task modification; options were specific diseases/medical conditions or "old age." The prevalence of "old age" citation as a cause of functional limitation, as well as its associated characteristics and medical conditions, was determined. MAIN RESULTS: Twenty percent of the 230 participants cited "old age" as the cause of their disability in two or more tasks. Tasks for which difficulty was most frequently attributed to "old age" were dressing oneself (31%), walking around the home (25%), walking 1/2 mile (5-6 blocks) (25%), cutting toenails (16%), getting in or out of a bed or chair or out a car (14% each), and ascending/descending stairs (13%). Significantly higher levels of arthritis, heart disease, and hearing loss were reported in persons attributing their disability to "old age" than in those not reporting "old age" as the cause of their disability. We found no differences in age, gender, race, education, or cognitive status for the two groups. However, individuals citing "old age" as the cause of functional decrements walked more slowly than those who cited a specific disease. CONCLUSIONS: These data suggest that a significant proportion of functional decline attributed to "aging" in older adults may be associated with specific conditions. Identifying and reducing the impact of these conditions may prove to be a useful approach to preventing or minimizing functional loss.

Activities of Daily Living↗
PubMed1995

Sequence analysis of a mannitol dehydrogenase cDNA from plants reveals a function for the pathogenesis-related protein ELI3.

Mannitol is the most abundant sugar alcohol in nature, occurring in bacteria, fungi, lichens, and many species of vascular plants. Celery (Apium graveolens L.), a plant that forms mannitol photosynthetically, has high photosynthetic rates thought to results from intrinsic differences in the biosynthesis of hexitols vs. sugars. Celery also exhibits high salt tolerance due to the function of mannitol as an osmoprotectant. A mannitol catabolic enzyme that oxidizes mannitol to mannose (mannitol dehydrogenase, MTD) has been identified. In celery plants, MTD activity and tissue mannitol concentration are inversely related. MTD provides the initial step by which translocated mannitol is committed to central metabolism and, by regulating mannitol pool size, is important in regulating salt tolerance at the cellular level. We have now isolated, sequenced, and characterized a Mtd cDNA from celery. Analyses showed that Mtd RNA was more abundant in cells grown on mannitol and less abundant in salt-stressed cells. A protein database search revealed that the previously described ELI3 pathogenesis-related proteins from parsley and Arabidopsis are MTDs. Treatment of celery cells with salicylic acid resulted in increased MTD activity and RNA. Increased MTD activity results in an increased ability to utilize mannitol. Among other effects, this may provide an additional source of carbon and energy for response to pathogen attack. These responses of the primary enzyme controlling mannitol pool size reflect the importance of mannitol metabolism in plant responses to divergent types of environmental stress.

Amino Acid Sequence↗
PubMed1995

Purification of NAD-dependent mannitol dehydrogenase from celery suspension cultures.

Mannitol dehydrogenase, a mannitol:mannose 1-oxidoreductase, constitutes the first enzymatic step in the catabolism of mannitol in nonphotosynthetic tissues of celery (Apium graveolens L.). Endogenous regulation on the enzyme activity in response to environmental cues is critical in modulating tissue concentration of mannitol, which, importantly, contribute to stress tolerance of celery. The enzyme was purified to homogeneity from celery suspension cultures grown on D-mannitol as the carbon source. Mannitol dehydrogenase was purified 589-fold to a specific activity of 365 mumol h-1 mg-1 protein with a 37% yield of enzyme activity present in the crude extract. A highly efficient and simple purification protocol was developed involving polyethylene glycol fractionation, diethylaminoethyl-anion-exchange chromatography, and NAD-agarose affinity chromatography using NAD gradient elution. Sodium dodecylsulfate gel electrophoresis of the final preparation revealed a single 40-kD protein. The molecular mass of the native protein was determined to be approximately 43 kD, indicating that the enzyme is a monomer. Polyclonal antibodies raised against the enzyme inhibited enzymatic activity of purified mannitol dehydrogenase. Immunoblots of crude protein extracts from mannitol-grown celery cells and sink tissues of celery, celeriac, and parsley subjected to sodium dodecyl sulfate gel electrophoresis showed a single major immuno-reactive 40-kD protein.

Amino Acid Sequence↗
PubMed1995

Increased fall rates in nursing home residents after relocation to a new facility.

OBJECTIVE: To examine the change in fall rates after relocation of nursing home residents from one facility to another and to identify resident risk factors for changes in falls following relocation. DESIGN: Retrospective review of incident reports to identify falls, followed by chart review of a longitudinal cohort. SETTING: An academic nursing home whose residents and programs moved from a 125-year-old, 233-bed facility to a newly constructed 255-bed facility. PATIENTS: A total of 210 nursing home residents were moved from one facility to the other. Of these, 133 individuals who lived in the old facility for 9 months before the move and in the new facility for 6 months after the move formed the longitudinal cohort. RESULTS: In the 3 months after the move, the fall rate increased from 0.34 to 0.70 falls per resident per quarter in the entire nursing home population (P < .001) and subsequently returned to baseline. In the longitudinal subgroup the fall rate went from 0.26 to 0.60 (P < .005). Fall-related injuries in the longitudinal subgroup went from 0.058 injuries per resident per quarter at baseline to 0.15 (P < .001). However, the injury rate per fall did not change. There were no characteristics associated with being a faller in the quarter before the move. Dementia and not being bedbound were associated with being a faller after the move. Individuals who were ambulatory or wheelchair mobile had a significant risk of increasing the number of falls after the move, and individuals with dementia had a strong but insignificant trend in this direction. CONCLUSIONS: The incidence of falling doubled after relocation of nursing home residents to a new facility. An increase in falls was seen in individuals who were not bedbound. Although nursing home relocation may be a relatively uncommon occurrence, it is reasonable to infer that older individuals who change their living environments are at increased risk for falls and fall-related injuries.

Accidental Falls↗
PubMed1994

The maize (Zea mays L.) Cat1 catalase promoter displays differential binding of nuclear proteins isolated from germinated and developing embryos and from embryos grown in the presence and absence of abscisic acid.

We previously demonstrated that amounts of Cat1 RNA in developing immature maize (Zea mays L.) embryos change in parallel with endogenous abscisic acid (ABA) content. In excised immature embryos, addition of ABA leads to a large increase in Cat1 RNA accumulation. The Cat1 transcript, however, also accumulates to high amounts in scutella of germinating embryos, where ABA content is low and decreasing. Here we show that application of ABA to germinated embryos no longer results in the up-regulation of the Cat1 transcript accumulation that is seen during embryogenesis. This suggests that factors other than ABA control Cat1 expression at this developmental stage. Using band-shift and southwestern analyses, we show that the change in sensitivity to ABA is paralleled by changes in nuclear proteins binding to a 28-bp region of the Cat1 promoter in vitro. One protein (CAT1BP-20) shows increased accumulation in the absence of ABA, suggesting that a repressor-mediated mechanism accounts for at least a portion of the ABA regulation of Cat1.

Abscisic Acid↗
PubMed1994

HIV-1 proviral DNA copy number in peripheral blood leucocytes and bronchoalveolar lavage cells of AIDS patients.

In this study we have determined by polymerase chain reaction (PCR) the quantity of HIV-1 proviral DNA in cells obtained by bronchoalveolar lavage (BAL) from the lung of HIV-1+ individuals. This has been compared quantitatively with the proviral DNA in peripheral blood leucocytes (PBL) obtained simultaneously from the same patients. The mean HIV DNA copy number per 10(6) cells was 391 for PBL, with a range of 1-9000, and 2971 for BAL cells, with a range of < 1-70,000. The quantity of HIV DNA detected in BAL cells was higher than that detected in the corresponding PBL samples in 44 out of 78 (56%) individuals, whilst more HIV DNA was detected in the PBL compared with BAL cells in 14 out of 78 (18%) patients. In both BAL and PBL higher levels of HIV DNA were detected in the adherent (monocyte/macrophage) enriched cell populations compared with other non-adherent cells (leucocytes). A direct relationship between HIV DNA copy number and ability to recover infectious HIV progeny in vitro by co-cultivation with cord blood leucocytes was found for both PBL and BAL cells. Individuals known to be receiving azidothymidine treatment had a lower mean HIV DNA load in all cell fractions compared with those patients on no antiretroviral therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Comparative study of the isolation of human immunodeficiency virus from the lung and peripheral blood of AIDS patients.

HIV-1 proviral DNA was detected by the polymerase chain reaction (PCR) in leucocytes from the peripheral blood (PBL) and bronchoalveolar lavage (BAL) of 100% and 72%, respectively, of HIV-1 seropositive patients. Infective virus isolated by cocultivation was recovered from the PBL and BAL of 50% and 59% of individuals, respectively. Isolation of HIV-1 was more readily made from the lung of individuals undergoing Pneumocystis carinii pneumonia (PCP) than from patients with non-PCP lung infections. The concomitant infection of lung cells with cytomegalovirus did not affect the isolation rate of HIV-1 from the lung. HIV-1 was isolated from BAL of 23 out of 36 (64%) individuals receiving no antiviral chemotherapy and from 13 out of 24 (54%) patients who were receiving AZT.

AIDS-Related Opportunistic Infections↗