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Biomedical subjects

P K Jones

Publications and source records attributed to P K Jones.

At least 19 recordsLinked to original sources
PubMed2005

Clinical determinants of poor six-minute walk test performance in patients with left ventricular systolic dysfunction and no major structural heart disease.

BACKGROUND: The clinical determinants of six-minute walk test (6-MWT) performance in patients with left ventricular systolic dysfunction (LVSD) have rarely been investigated, and it is not clear whether they differ from patients referred for the assessment of symptoms of heart failure who do not have major structural heart disease (MSHD). METHODS AND RESULTS: 571 patients with LVSD enrolled in a chronic disease management programme (79% male; mean age 71+/-10 years; BMI 28+/-5) completed a 6-MWT with a mean distance 337+/-103 m. 688 patients referred with suspected heart failure but in whom MSHD was excluded (49% male; mean age 70+/-11 years; BMI 28+/-6) had a mean 6-MWT distance of 391+/-106 m (P<0.001 compared to patients with LVSD). Relationships with walking distance were determined by calculating odds ratios (ORs) with 95% confidence intervals (CIs) for walking 300 m. In patients with LVSD, predictors of poor walking distance ( or=75 years (OR=4.0, 95% CI=2.4-6.4); low BMI (<20) (OR=3.4, 95% CI=1.6-7.3); anaemia (OR=2.8, 95% CI=1.8-4.2); resting heart rate>80 beats x min(-1) (OR=2.2, 95% CI=1.3-3.5); and being female (OR=2.0, 95% CI=1.3-3.0). Serum creatinine and NT-proBNP showed dose-response effects, as did self-perceived feelings of depression and anxiety. Determinants of 6-MWT in patients without MSHD were similar including age>or=75 years (OR=6.0, 95% CI=3.4-10.4), anaemia (OR=2.8, 95% CI=1.6-4.9), resting HR>80 beats x min(-1) (OR=2.5, 95% CI=1.4-4.4) and being female (OR=1.6, 95% CI=1.9-2.4). NT-proBNP and self-perceived feelings of depression and anxiety also showed dose-response effects. CONCLUSION: The determinants of poor 6-MWT performance depend on physical-cardiovascular and non-cardiovascular, and psychological factors. Clinical predictors for poor walking performance are similar for patients with LVSD and without MSHD.

Aged↗
PubMed2001

Mitochondrial abnormalities in Alzheimer's disease.

The finding that oxidative damage, including that to nucleic acids, in Alzheimer's disease is primarily limited to the cytoplasm of susceptible neuronal populations suggests that mitochondrial abnormalities might be part of the spectrum of chronic oxidative stress of Alzheimer's disease. In this study, we used in situ hybridization to mitochondrial DNA (mtDNA), immunocytochemistry of cytochrome oxidase, and morphometry of electron micrographs of biopsy specimens to determine whether there are mitochondrial abnormalities in Alzheimer's disease and their relationship to oxidative damage marked by 8-hydroxyguanosine and nitrotyrosine. We found that the same neurons showing increased oxidative damage in Alzheimer's disease have a striking and significant increase in mtDNA and cytochrome oxidase. Surprisingly, much of the mtDNA and cytochrome oxidase is found in the neuronal cytoplasm and in the case of mtDNA, the vacuoles associated with lipofuscin. Morphometric analysis showed that mitochondria are significantly reduced in Alzheimer's disease. The relationship shown here between the site and extent of mitochondrial abnormalities and oxidative damage suggests an intimate and early association between these features in Alzheimer's disease.

Adolescent↗
PubMed2001

Quantitative contributions of gluconeogenesis to glucose production during fasting in type 2 diabetes mellitus.

Contributions of gluconeogenesis to glucose production were determined between 14 to 22 hours into a fast in type 2 diabetics (n = 9) and age-weight-matched controls (n = 7); ages, 60.4 +/- 2.3 versus 55.6 +/- 1.2 years and body mass indices (BMI) 28.6 +/- 2.3 versus 26.6 +/- 0.8 kg/m2. Production was measured using a primed-continuous [6,6-2H2]glucose infusion and gluconeogenesis from 2H enrichment at carbons 2 and 5 of blood glucose on 2H2O ingestion. Plasma glucose concentration declined from 9.6 +/- 0.6 at 14 hours to 7.3 +/- 0.6 at 22 hours in the diabetics (P = .001) and from 5.4 +/- 0.1 to 5.0 +/- 0.1 in the controls (P < .05). Production from the 17th to 22nd hour declined 27.1% +/- 0.6% in the diabetics versus 18.5% +/- 0.8% in the controls (P = .001); from 10.4 +/- 0.3 to 7.6 +/- 0.2 versus 10.0 +/- 0.4 to 8.2 +/- 0.4 micromol/kg/min. Percent contributions of gluconeogenesis to production measured at 1 1/2 to 2-hour intervals beginning the 15th hour were 6.8% +/- 1.0% more in the diabetics than controls. The quantity of glucose contributed by gluconeogenesis declined 19.8% +/- 3.8% (P < .001) in the diabetics and 6.9% +/- 2.3% in the controls (P = .05); 7.21 +/- 0.32 to 5.74 +/- 0.26 versus 6.20 +/- 0.28 to 5.75 +/- 0.24 micromol/kg/min. The contribution of glycogenolysis to production, estimated from the difference between production and gluconeogenesis, declined to the same extent in diabetic and control subjects, 40.7% +/- 6.6% and 37.7% +/- 4.1%; from 3.23 +/- 0.35 to 1.86 +/- 0.26 versus 3.81 +/- 0.22 to 2.42 +/- 0.28 micromol/kg/min. Thus, gluconeogenesis contributed more to glucose production in the diabetic than control subjects. Production and the contribution of gluconeogenesis declined more in the diabetic subjects during the fast. The factors regulating these changes remain uncertain.

Deuterium↗
PubMed2001

Oxidative damage is the earliest event in Alzheimer disease.

Recently, we demonstrated a significant increase of an oxidized nucleoside derived from RNA, 8-hydroxyguanosine (8OHG), and an oxidized amino acid, nitrotyrosine in vulnerable neurons of patients with Alzheimer disease (AD). To determine whether oxidative damage is an early- or end-stage event in the process of neurodegeneration in AD, we investigated the relationship between neuronal 8OHG and nitrotyrosine and histological and clinical variables, i.e. amyloid-beta (A beta) plaques and neurofibrillary tangles (NFT), as well as duration of dementia and apolipoprotein E (ApoE) genotype. Our findings show that oxidative damage is quantitatively greatest early in the disease and reduces with disease progression. Surprisingly, we found that increases in A beta deposition are associated with decreased oxidative damage. These relationships are more significant in ApoE epsilon4 carriers. Moreover, neurons with NFT show a 40%-56% decrease in relative 8OHG levels compared with neurons free of NFT. Our observations indicate that increased oxidative damage is an early event in AD that decreases with disease progression and lesion formation. These findings suggest that AD is associated with compensatory changes that reduce damage from reactive oxygen.

Aged↗
PubMed2000

Sustained personal autonomy: a measure of successful aging.

OBJECTIVES: This study addresses the following question: What characteristics of urban, noninstitutionalized elders predict which individuals are most likely to remain independent of personal assistance during a 2-year observation period? METHODS: A population-based sample of 602 noninstitutionalized urban residents aged 70 and older was followed for 2 years. RESULTS: Ninety-eight of the 487 survivors remained independent. Factors associated with sustained independence were relatively younger age, male gender, fewer medical conditions, good physical function, and nonsmoking. The attitudes "favors family or self over agency assistance" and "does not expect filial obligation" were also independently associated. DISCUSSION: The results are consistent with previous studies of successful aging and show that attitudes expressed at baseline favoring personal independence are associated with sustained autonomy during a period of at least 2 years.

Age Factors↗
PubMed1999

Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis.

BACKGROUND: We studied the incidence, prevalence, and radiographic progression of symptomatic adjacent-segment disease, which we defined as the development of new radiculopathy or myelopathy referable to a motion segment adjacent to the site of a previous anterior arthrodesis of the cervical spine. METHODS: A consecutive series of 374 patients who had a total of 409 anterior cervical arthrodeses for the treatment of cervical spondylosis with radiculopathy or myelopathy, or both, were followed for a maximum of twenty-one years after the operation. The annual incidence of symptomatic adjacent-segment disease was defined as the percentage of patients who had been disease-free at the start of a given year of follow-up in whom new disease developed during that year. The prevalence was defined as the percentage of all patients in whom symptomatic adjacent-segment disease developed within a given period of follow-up. The natural history of the disease was predicted with use of a Kaplan-Meier survivorship analysis. The hypothesis that new disease at an adjacent level is more likely to develop following a multilevel arthrodesis than it is following a single-level arthrodesis was tested with logistic regression. RESULTS: Symptomatic adjacent-segment disease occurred at a relatively constant incidence of 2.9 percent per year (range, 0.0 to 4.8 percent per year) during the ten years after the operation. Survivorship analysis predicted that 25.6 percent of the patients (95 percent confidence interval, 20 to 32 percent) who had an anterior cervical arthrodesis would have new disease at an adjacent level within ten years after the operation. There were highly significant differences among the motion segments with regard to the likelihood of symptomatic adjacent-segment disease (p<0.0001); the greatest risk was at the interspaces between the fifth and sixth and between the sixth and seventh cervical vertebrae. Contrary to our hypothesis, we found that the risk of new disease at an adjacent level was significantly lower following a multilevel arthrodesis than it was following a single-level arthrodesis (p<0.001). More than two-thirds of all patients in whom the new disease developed had failure of nonoperative management and needed additional operative procedures. CONCLUSIONS: Symptomatic adjacent-segment disease may affect more than one-fourth of all patients within ten years after an anterior cervical arthrodesis. A single-level arthrodesis involving the fifth or sixth cervical vertebra and preexisting radiographic evidence of degeneration at adjacent levels appear to be the greatest risk factors for new disease. Therefore, we believe that all degenerated segments causing radiculopathy or myelopathy should be included in an anterior cervical arthrodesis. Although our findings suggest that symptomatic adjacent-segment disease is the result of progressive spondylosis, patients should be informed of the substantial possibility that new disease will develop at an adjacent level over the long term.

Adolescent↗
PubMed1998

Cerebrovascular muscle atrophy is a feature of Alzheimer's disease.

We examined vascular amyloid-beta deposition and other abnormalities in the posterior cerebral artery of consecutive cases of Alzheimer's disease (AD) compared to controls. Smooth muscle atrophy was a consistent feature in the cases of AD examined (p<0.01) and was surprisingly independent of adjacent amyloid-beta deposition. These findings suggest that vascular abnormalities are a consistent feature in AD and may be an important contributor to the pathogenesis and complications of AD.

Adult↗
PubMed1998

Patients as partners in clinical research: a proposal for applying quality improvement methods to patient care.

OBJECTIVES: The authors show the potential value of using statistical process control (SPC) methods to measure change in health status for patients with chronic conditions. Examples will be used to compare the strengths and weaknesses of these methods to randomized clinical trials (RCTs). METHODS: Run charts, control charts, and regression models are used to explain variations in patients' hypertension and diabetes. RESULTS: Significant improvements are shown in the examples given using the Western Electric rules. CONCLUSIONS: These SPC methods can be used for self-management of chronic conditions. They provide a new set of tools for measuring health care outcomes.

Chronic Disease↗
PubMed1998

Anterior cervical decompression and arthrodesis for the treatment of cervical spondylotic myelopathy. Two to seventeen-year follow-up.

We reviewed the cases of 108 patients with cervical spondylotic myelopathy who had been managed with anterior decompression and arthrodesis at our institution. Operative treatment consisted of anterior discectomy, partial corpectomy, or subtotal corpectomy at one level or more, followed by placement of autogenous bone graft from the iliac crest or the fibula. At the latest follow-up examination, thirty-eight of the eighty-two patients who had had a preoperative gait abnormality had a normal gait, thirty-three had an improvement in gait, six had no change, four had improvement and later deterioration, and one had a worse gait abnormality. Of the eighty-seven patients who had had a preoperative motor deficit, fifty-four had complete recovery; twenty-six, partial recovery; six, no change; and one had a worse deficit. The average grade according to the system of Nurick improved from 2.4 preoperatively to 1.2 (range, 0.0 to 5.0) postoperatively. A pseudarthrosis developed in sixteen patients, thirteen of whom had had a multilevel discectomy. Only one of thirty-eight arthrodeses that had been performed with use of a fibular strut graft was followed by a non-union. An unsatisfactory outcome with respect to pain was significantly associated with pseudarthrosis (p < 0.001). The development of complications other than non-union was associated with a history of one previous operative procedure or more (p = 0.005). Recurrent myelopathy was rare, but when it occurred it was associated with a pseudarthrosis or stenosis at a new level. The strongest predictive factor for recovery from myelopathy was the severity of the myelopathy before the operative intervention--that is, better preoperative neurological function was associated with a better neurological outcome. Anterior decompression and arthrodesis with autogenous bone-grafting can be performed safely, and is associated with a high rate of neurological recovery, functional improvement, and pain relief, in patients who have cervical spondylotic myelopathy.

Adult↗
PubMed1996

In vitro backscattering from implant materials during radiotherapy.

It is a certainty that many of the patients now receiving dental implants will one day require radiotherapy if they have head and neck cancer. The purpose of this study was to examine the dose enhancement form backscattered radiation at implant/bone interfaces irradiated with high-energy 6 MV and 10 MV x-rays. Three commonly used implant materials, pure titanium, Ti-6A1-4V alloy, and a high gold content implant material of various thicknesses, were used to measure the dose enhancement caused by backscattered radiation. The relative ionization charges at implant/bone interfaces were measured at distances of 0, 1, 2, and 3 mm away from the implant material by insertion of 0, 1, 2, and 3 mm thick bone substitute disks between the implant material and an ionization chamber. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the implant/bone interface for all the materials studied. The Au-Cu-Ag implant material had more average relative dose than pure titanium or Ti-6A1-4V alloy. The backscattered electrons decreased as the thickness of the bone substitute (distance between the implant material and the ionization chamber) increased.

Alloys↗
PubMed1995

Acute respiratory illness in older community residents.

OBJECTIVE: To describe the 3-year incidence of acute respiratory illness in a population of noninstitutionalized elderly persons. DESIGN: Cohort analytic study with an observation period of 3 years. SETTING: Large midwestern urban community. SUBJECTS: 574 noninstitutionalized persons aged 65 years and older, of whom 349 were living independently, 110 were in congregate settings, and 115 were living independently and regularly caring for small children. METHODS: Subjects were interviewed and examined by nurse practitioners at intake and every 4 months. Acute illness and convalescent visits were made when illnesses were reported by participants. MAIN OUTCOME MEASURES: The incidence of acute respiratory illness was used to test the hypothesis that elderly persons taking care of children have the highest incidence, congregate-dwellers intermediate incidence, and those living independently the lowest incidence. RESULTS: The average incidence of acute respiratory illness was 2.5 per 100 person months, comparable to rates reported in the National Health Survey. The incidence of respiratory illness was significantly greater in subjects living in congregate settings or regularly caring for young children. Similarly, greater proportions of persons in the congregate and child-care groups reported at least one episode of illness (P < .05). A more detailed analysis of exposure shows that acute respiratory illness was significantly more common in subjects who had contact with children (P < .05). This risk was definitely present during the months November through February, and probably also during July through October, but was not observed for March through June. CONCLUSIONS: Elderly persons living in the community experience low rates of acute upper respiratory illness. Contact with children increases their risk of developing such illnesses during certain seasons of the year.

Activities of Daily Living↗
PubMed1995

Effect of demographic and behavioral variables on burden of caregivers of chronic mentally ill persons.

OBJECTIVE: Persons who provide care for individuals with chronic mental illness experience both objective burden (observable, tangible cost) and subjective (perceived) burden. This study sought to determine the relative power of behaviors of chronic mentally ill clients, behaviors required of caregivers, and demographic characteristics of both groups in predicting burden. METHODS: A total of 189 caregiver-client dyads were studied using a cross-sectional, correlational design. Caregivers were interviewed by phone about clients' needs for help in nine areas and about seven potentially troublesome client behaviors. Correlation and regression analyses were used to determine relationships among variables. RESULTS: Caregivers reported much less subjective than objective burden, although the relationship between the two types of burden was not consistent across the various areas in which clients needed help. Overall, more of the reported burden was related to caregivers' behaviors (their day-to-day tasks) than to clients' behaviors. Burden was greatly increased for caregivers who lived with the client. Caregivers most at risk for burden were those who lived with male clients who threatened suicide. CONCLUSIONS: Caregivers become accustomed to the stabilized behavioral profile of the client. Mental health professionals should be sensitive to profiles and situations that may produce increased objective and subjective caregiver burden.

Adult↗
PubMed1994

Robinson anterior cervical fusion comparison of the standard and modified techniques.

In 1990 the authors modified the Robinson anterior cervical interbody fusion technique by burring the endplates to expose subchondral bone. The authors compared 31 patients having the standard technique and 29 patients having the modified technique to evaluate 1) setting of the bone graft, 2) kyphotic angulation, 3) pseudarthrosis rate, and 4) pain outcome. In the standard Robinson fusion technique, the average loss of height across the fused segments was 0.8 mm and the average increase in kyphosis 4.9 degrees. Values for the modified technique were 1.9 mm and 3.1 degrees, respectively. The change in height was statistically significant (P = .01), as was the difference in angulation (P = .028), though the latter was in the opposite direction predicted. The pseudarthrosis rate using the modified technique decreased to 4.4% per level. Pain outcome for the two groups was equivalent. Burring of the endplates for anterior cervical interbody arthrodesis results in a detectable but not clinically important amount of graft settling with a higher success rate for arthrodesis.

Bone Transplantation↗
PubMed1994

Caregiver burden: who the caregivers are, how they give care, and what bothers them.

The present research describes the association between objective and subjective caregiver burden experienced by families and friends of individuals with chronic mental illness. Although there has been a significant quantity of research conducted about burden and mental illness, the findings have been equivocal because of varying definitions of burden and varying sampling procedures. The present research utilizes a standardized interview instrument for caregivers. Caregivers were named by a stratified random sample of clients who have been certified as severely mentally disabled and have received publicly-funded community mental health services in the state of Ohio during the 1990 fiscal year. Data were collected by the first author and a research assistant during telephone interviews between August 1991 and May 1992. One hundred and eighty-nine caregivers were interviewed. Findings showed that the majority of caregivers are female, white, and aged 50 years or more. Parents comprise the largest group of caregivers and slightly more than one third of clients live with the caregiver. The relationship between caregiver and client is generally described as positive; however, the interviews were conducted during a period when the clients' symptomatology was more under control than previously in the relationship. Caregivers state that the clients need help much more often than they ask for it in all categories of possible help. Considering caregiver burden in relation to caregiver behaviors, time management is a somewhat frequent problem that is very troublesome to the caregiver. Considering client behaviors in relation to caregiver burden, embarrassing behaviors are most troublesome and occur with moderate frequency. The surprise element of these behaviors seems to be the most problematic.

Adolescent↗
PubMed1994

The impact of systemic lupus erythematosus on women's sexual functioning.

OBJECTIVE: We investigated the impact of systemic lupus erythematosus (SLE) and the mediating effects of psychosocial factors on women's sexual adjustment. METHODS: Data were obtained through structured interviews and psychometric scales administered to 100 female subjects with SLE and 71 disease-free controls. RESULTS: Compared with controls, patients with SLE had a significantly higher rate of abstention (26 vs 4%, p < 0.01), a lower frequency of sexual activity among the sexually active (p < 0.05), diminished vaginal lubrication (p < 0.01), and poorer general sexual adjustment (p < 0.01). Greater disease severity was associated with more impairment in sexual function (p < 0.01). Variables mediating the relationship between diagnostic status and sexual outcome included age (delta R2 = 0.04, p < 0.01), relationship status (delta R2 = 0.03, p < 0.05), weight concerns (delta R2 = 0.05, p < 0.01), premorbid sexual adjustment (delta R2 = 0.04, p < 0.01), and depression (delta R2 = 0.03, p < 0.05). Seventy-two percent of patients with SLE were receptive to physician inquiry about sexual functioning and 82% desired further education about the sexual impact of the disease. CONCLUSION: Our results suggest that sexual impairment is not inevitable among women with SLE. The role that providers can play in helping to prevent sexual difficulties is discussed.

Adult↗
PubMed1993

Medical and psychosocial predictors of sexual outcome among women with systemic lupus erythematosus.

The influence of medical and psychosocial variables on sexual outcome in 100 women with systemic lupus erythematosus was examined. Subjects were administered a sexual adjustment interview and scales assessing depression, body image, and relationship quality. Medical data were obtained from patients and physicians. Key predictors of sexual outcome were disease severity (P < 0.001), premorbid sexual adjustment (P < 0.05), and relationship quality (P < 0.05). Results suggest that the impact of systemic lupus erythematosus on sexual response may best be understood by considering a combination of interpersonal, psychological, and medical conditions in a patient's life.

Adult↗
PubMed1993

Relationship between arterial thrombosis and neutralization of a polyethylene ionomer.

The influence of three levels of sodium neutralization of an ethylene/methacrylic acid copolymer on in vivo blood compatibility was studied in a canine arterial model. Effects due to sample fabrication methods (thermal pressing versus solution casting) were also monitored. Sodium content, sodium release, hydrogen dissociation, and localization of anionic groups were noted. Polymer surface energy, surface morphology, water uptake, and thermal properties were characterized. Material characterization and in vivo implantation disclose the following: 1) Thermal pressing generated oxidation degradation products that decreased in vivo blood compatibility. Solution-cast samples adhered and activated fewer blood elements. 2) Platelets and leukocytes were sensitive to differences in shear rate in the carotid and femoral arteries, with the femoral site tending toward higher shear, more platelet deposition and fewer leukocytes. 3) The surface properties of the polyethylene control, 0% Na, and 50% Na samples tended to be similar. These properties were different from the 100% Na sample. The 100% Na ionomer was more hydrophilic, had a higher polar component for its surface energy, and was unique in exhibiting discrete ionic clusters 1-10 microns in diameter on its surface. 4) These differences were manifested in vivo by platelet activation and thrombus development on the polyethylene, 0% Na, and 50% Na implants, while the 100% Na implant surfaces were predominantly covered by singly adherent, unactivated platelets. 5) It is proposed that the improvement in biocompatibility for the 100% Na ionomer is due to the cluster development in the neutralized methacrylic component and that either directly, or through appropriate protein adsorption and/or conformational adjustment to the cluster regions, platelets are not activated and do not initiate the coagulation mechanism.

Absorption↗