Biomedical subjects

E Park

Publications and source records attributed to E Park.

At least 73 records · Page 4Linked to original sources

PubMed1998

Home care in Canada.

OBJECTIVES: This article describes the social, socioeconomic and other health-related characteristics of people receiving formal, publicly funded home care services. DATA SOURCE: The data are from the household component of the 1994/95 National Population Health Survey. The analysis covers 16,291 respondents aged 18 or older. ANALYTICAL TECHNIQUES: Recipients of publicly funded home care services were profiled using weighted univariate frequencies and multivariate logistic regression. MAIN RESULTS: Recipients of publicly funded home care services in 1994/95 numbered over half a million. People who were elderly, female, had two or more chronic conditions or were living with others accounted for large proportions of these recipients. Characteristics significantly associated with receiving home care included old age, poor or fair general health, abstinence from alcohol (compared with regular use), low income, living alone, needing help with some activity of daily living, and having cancer or the effects of a stroke.

Activities of Daily Living↗

PubMed1997

Anti-IgM-induced growth inhibition and apoptosis are independent of ornithine decarboxylase in Ramos cells.

Ornithine decarboxylase (ODC) is a key enzyme involved in polyamine production and is thought to regulate growth and apoptosis in multiple cell systems. A potential link between ODC and growth may involve the action of an oncogene c-myc which is thought to transcriptionally regulate ODC. We have examined the involvement of ODC in anti-IgM-induced growth inhibition and apoptosis in Burkitt's lymphoma cells. Inhibitors of ODC such as difluoromethylornithine (DFMO) completely blocked ODC activity, resulting in growth inhibition but not apoptosis. Addition of putrescine, the product of ODC enzymatic action, to Ramos cells had only a minor effect on growth, did not cause apoptosis, did not augment or block anti-IgM-mediated growth inhibition and apoptosis, but did reverse DFMO-mediated growth inhibition. Anti-IgM treatment of Ramos cells, which markedly decreased c-myc mRNA and protein, caused a paradoxical increase in ODC mRNA level as well as ODC enzymatic activity and increased cellular levels of putrescine. DFMO and putrescine did not alter c-myc mRNA levels directly, nor did they have any affects on anti-IgM-mediated down-regulation of c-myc mRNA. TNF-alpha, which inhibited anti-IgM-mediated apoptosis, did not inhibit either anti-IgM or DFMO-mediated inhibition of growth. These agents were without effect on ODC activity itself or on the anti-IgM-mediated increase in ODC activity. From these studies we conclude that ODC inhibition affects growth but is unrelated to the induction of apoptosis. Both anti-IgM-mediated inhibition of growth and induction of apoptosis are independent of ODC. Thus two distinct pathways for growth regulation are present: one in which ODC and polyamines are important and the other cell surface receptor-mediated (sIg) which is independent of ODC and polyamines.

Apoptosis↗

PubMed1997

Reported emissions of organic gases are not consistent with observations.

Regulatory agencies and photochemical models of ozone rely on self-reported industrial emission rates of organic gases. Incorrect self-reported emissions can severely impact on air quality models and regulatory decisions. We compared self-reported emissions of organic gases in Houston, Texas, to measurements at a receptor site near the Houston ship channel, a major petrochemical complex. We analyzed hourly observations of total nonmethane organic carbon and 54 hydrocarbon compounds from C-2 to C-9 for the period June through November, 1993. We were able to demonstrate severe inconsistencies between reported emissions and major sources as derived from the data using a multivariate receptor model. The composition and the location of the sources as deduced from the data are not consistent with the reported industrial emissions. On the other hand, our observationally based methods did correctly identify the location and composition of a relatively small nearby chemical plant. This paper provides strong empirical evidence that regulatory agencies and photochemical models are making predictions based on inaccurate industrial emissions.

Journal Article↗

PubMed1997

Radiosurgery for brain metastases: relationship of dose and pattern of enhancement to local control.

PURPOSE: This study aimed to analyze dose, initial pattern of enhancement, and other factors associated with freedom from progression (FFP) of brain metastases after radiosurgery (RS). METHODS AND MATERIALS: All brain metastases treated with gamma-knife RS at the University of California, San Francisco, from 1991 to 1994 were reviewed. Evaluable lesions were those with follow-up magnetic resonance or computed tomographic imaging. Actuarial FFP was calculated using the Kaplan-Meier method, measuring FFP from the date of RS to the first imaging study showing tumor progression. Controlled lesions were censored at the time of the last imaging study. Multivariate analyses were performed using a stepwise Cox proportional hazards model. RESULTS: Of 261 lesions treated in 119 patients, 219 lesions in 100 patients were evaluable. Major histologies included adenocarcinoma (86 lesions), melanoma (77), renal cell carcinoma (21), and carcinoma not otherwise specified (17). The median prescribed RS dose was 18.5 Gy (range, 10-22) and the median tumor volume was 1.3 ml (range, 0.02-30.9). The initial pattern of contrast enhancement was homogeneous in 68% of lesions, heterogeneous in 12%, and ring-enhancing in 19%. The actuarial FFP was 82% at 6 months and 77% at 1 year for all lesions, and 93 and 90%, respectively, for 145 lesions receiving > or = 18 Gy. Multivariate analysis showed that longer FFP was significantly associated with higher prescribed RS dose, a homogeneous pattern of contrast enhancement, and a longer interval between primary diagnosis and RS. Adjusted for these factors, adenocarcinomas had longer FFP than melanomas. No significant differences in FFP were noted among lesions undergoing RS for recurrence after prior radiotherapy (119 lesions), RS alone as initial treatment (45), or RS boost (55). CONCLUSION: A minimum prescribed radiosurgical dose > or = 18 Gy yields excellent local control of brain metastases. The influence of pattern of enhancement on local control, a new finding in this retrospective analysis, needs to be confirmed.

Adenocarcinoma↗

PubMed1997

Preactivation exposure of RAW 264.7 cells to taurine chloramine attenuates subsequent production of nitric oxide and expression of iNOS mRNA.

Recent studies demonstrate that taurine chloramine (Tau-Cl) inhibits production of nitric oxide (NO) and other proinflammatory mediators in cultured macrophages when added to the media at the time of activation. Because Tau-Cl may react with various media constituents and it is difficult to measure Tau-Cl in complex solutions, we designed experiments to more carefully control cell exposure to various chloramines and NaOCl. RAW 264.7 cells were exposed to 1 mM of NaOCl, Tau-Cl, or chloramine preparations of the following amino acids: L-alanine (L-Ala-Cl), beta-alanine (beta-Ala-Cl), serine (Ser-Cl), or glycine (Gly-Cl) in Hanks' balanced salt solution (HBSS) for up to 2 h (37 degrees C, 5% CO2). The HBSS solution was then replaced with complete media containing interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) for an additional 24 h before measuring cell viability. The chemical stability of NaOCl and each chloramine was evaluated after various times of preactivation exposure by measuring retention of each solution's UV absorption spectra and ability to oxidize KI. Cytotoxicity of each solution was evaluated by the maintained ability of RAW 264.7 cells to reduce MTT. Whereas Tau-Cl, beta-Ala-Cl, and Gly-Cl were stable chloramines, only Tau-Cl was not cytotoxic. L-Ala-Cl, Ser-Cl, and the highly reactive oxidant NaOCl were unstable and toxic. In further studies RAW 264.7 cells were exposed to Tau-Cl in HBSS for 2 h and the solution was then replaced with complete media containing IFN-gamma and LPS, taxol, lipoarabinomannan, or interleukin-2. Production of NO was measured 24 h later and was inhibited in activated cells that were previously exposed to Tau-Cl. Inhibition of NO production was dependent on Tau-Cl concentration and was accounted for by reduced expression of inducible nitric oxide synthase mRNA, regardless of activator combinations. These results support the idea that Tau-Cl has the potential to function as an inhibitory modulator of inflammations.

Animals↗

PubMed1997

Leukocytes in neuronal ceroid-lipofuscinoses: function and apoptosis.

The neuronal ceroid-lipofuscinoses (NCL) are a group of progressive encephalopathies with a fatal course that are mostly of autosomal recessive inheritance. The pathophysiological mechanisms causing the diseases are not known. The characteristic histomorphological feature of the NCL is an abnormal lysosomal accumulation of lipopigments in neural and extraneural cells, including peripheral blood leukocytes. We studied the function of peripheral venous blood immunocompetent cells in ten patients with NCL and in age- and sex-matched controls to determine how, if at all, the accumulation of intracytoplasmic storage material influences the functional capacity of affected tissue. Our results did not reveal any functional impairment of affected cells, but rather suggested a higher turnover rate in NCL. Apoptosis was increased, suggesting that abnormally controlled programmed cell death might play an important role in the pathogenesis of NCL.

Adolescent↗

PubMed1997

Multiple urinary cytokine levels of bacterial cystitis.

PURPOSE: We have examined urinary cytokine levels to define the inflammatory response in patients with bacterial cystitis or microhematuria relative to normal subjects. Cytokines examined include interleukin-1beta (IL-1beta), IL-1alpha, tumor necrosis factor (TNF alpha), IL-6 and IL-4. Unique features of this study include a) a simultaneous study of several relevant cytokines b) a study of the inflammatory response at both low and high counts of bacterial infection and c) an assessment of whether microhematuria without bacterial cystitis or pyuria is associated with cytokine elevation compared to normals. MATERIALS AND METHODS: Enzyme immunoassays were utilized for each cytokine. Patients studied include those with bacterial cystitis (n = 49), patients with microhematuria (n = 11), and normal subjects (n = 36). Cytokine levels were also determined for patients with low count bacterial cystitis (1,000-50,000 organisms; n = 15) and compared to high count bacterial cystitis (>100,000 organisms; n = 34) and normal subjects. Statistical analysis was carried out using the Kruskal-Wallis test followed by pairwise testing with Newman-Keuls test. RESULTS: a) The means for normal, microhematuria and bacterial cystitis groups were significantly different (p <0.05) for IL-1beta, IL-1alpha, TNF alpha and IL-6, but not for IL-4. b) Except for IL-4, all cytokines were found to be significantly elevated in low count bacterial cystitis compared to normals. No statistically significant difference was observed between low and high count bacterial cystitis groups for any of the cytokines tested. CONCLUSIONS: a) Significant and similar inflammatory responses are present in both low and high count bacterial cystitis groups as compared with the normal group. b) IL-6 and TNF alpha are significantly elevated in patients with microhematuria compared to normals. c) The potential clinical utility of the assays lies in identifying the specific cytokines elevated, understanding the pathways that give rise to their production, and in defining potential virulence factors that may produce significant inflammation at low count bacterial infections.

Colony Count, Microbial↗

PubMed1997

Characteristics of hospital users.

OBJECTIVES: For people living in the community, this article explores selected health problems and personal characteristics that are associated with having been hospitalized. DATA SOURCE: The data, collected from a sample of people aged 15 and over living in 27,263 households in the 10 provinces, are from the household component of the 1994/95 National Population Health Survey. ANALYTICAL TECHNIQUES: Bivariate and multiple regression analyses were used to determine associations between hospitalization and chronic health problems, demographic characteristics, health-related behaviours, and socioeconomic status. MAIN RESULTS: Having cancer or a long-term disability was strongly associated with hospitalization throughout adulthood. Among women under age 65, the odds of hospitalization were higher among those with inadequate income than among those with adequate income, even after controlling for differences in health status.

Adolescent↗

PubMed1996

Anti-IgM-mediated regulation of c-myc and its possible relationship to apoptosis.

Anti-IgM treatment of Burkitt's lymphoma cells is followed by either growth arrest or induction of apoptosis. In this study we have explored the role of c-myc in these events. Our results in Ramos cells indicate the following. (a) The decline in c-myc mRNA occurs at about 4 h; inhibition of about 80% being observed. (b) The stability of c-myc message is involved since the half-life of c-myc mRNA is decreased from about 30 min in untreated cells to about 15 min following treatment with anti-IgM. In the presence of cycloheximide, a protein synthesis inhibitor, the half-life is increased to about 50 min and was unaltered by treatment with anti-IgM. (c) By contrast, nuclear run-on experiments indicated no change in transcription rates for c-myc message due to treatment with anti-IgM. (d) A decrease in c-myc causes apoptosis since specific repression of c-myc with antisense oligonucleotides decreases the levels of c-Myc, inhibits growth rate, decreases viability, and induces apoptosis. (e) Anti-CD40 inhibition of apoptosis occurs without alteration in anti-IgM-induced down-regulation of c-myc mRNA, suggesting that it acts distally to c-myc down-regulation. Other cell lines were also investigated. In Epstein-Barr virus (EBV)-positive cell lines (Daudi, Raji, and Namalwa), anti-IgM treatment for 24 h results in growth inhibition without induction of apoptosis. In EBV-negative cell lines (ST486 and CA46, as well as Ramos), a more heterogeneous pattern of responses to anti-IgM are observed. Ramos and ST486 cells both show growth inhibition and apoptosis upon anti-IgM treatment; CA46 cells shown only growth inhibition but not apoptosis. Anti-IgM causes a decline in c-myc mRNA levels in all of these lines, as well as in c-Myc protein level in the two lines investigated, Daudi and Ramos, regardless of apoptosis. Addition of antisense c-myc oligonucleotides to the cells reduced growth in both Daudi and Ramos cells lines, however it resulted in substantial apoptosis only in Ramos cells. These results suggest that anti-IgM destabilizes c-myc mRNA by a process that involves mRNA turnover, rather than transcription rates. However anti-IgM exerts differential effects in EBV-positive and EBV-negative cell lines. EBV-positive cells are uniformly resistant to apoptosis, while EBV-negative cell lines show a tendency to apoptosis but with exceptions. Growth inhibition can be uncoupled from apoptosis in EBV-positive cell lines, but not in those EBV-negative cell lines prone to apoptosis. Furthermore, down-regulation of c-myc message correlates with growth inhibition in these cells, but is an insufficient link to apoptosis. By contrast inhibition of apoptosis by anti-CD40 occurs even though c-myc mRNA is decreased.

Antibodies, Anti-Idiotypic↗

PubMed1996

TNF-alpha inhibits anti-IgM-mediated apoptosis in Ramos cells.

We have examined the effects of tumor necrosis factor-alpha (TNF-alpha) as an inducer or modulator of necrosis and/or apoptosis in B cell lines. TNF-alpha does not induce either necrosis or apoptosis in EBV-positive or -negative cell lines, regardless of the culture conditions of the cells or the presence or absence of cytokines. By contrast anti-IgM induces apoptosis in two EBV-negative cell lines (Ramos and ST486) but not in EBV-positive cell lines. Since TNF receptor and CD40 belong to the TNF receptor superfamily and anti-CD40 is a known inhibitor of apoptosis, we tested for TNF-alpha's effects on the inhibition of apoptosis induced by anti-IgM. Our results indicate that TNF-alpha inhibits apoptosis induced by anti-IgM in Ramos cells but not in ST486. The effects are dose and time dependent; the degree of apoptosis achieved and the selectivity of the effect among cell lines are strikingly similar for both TNF-alpha and anti-CD40. Furthermore when both agents are tested together no additivity in the inhibition is observed. The inhibition of apoptosis is a direct effect of TNF-alpha and not a permissive effect of another cytokine, since it is observed in defined medium. Although anti-IgM induces both TNF-alpha secretion and TNF receptors in Ramos cells, the concentration of secreted TNF-alpha is too low to affect apoptosis. Inhibition does not involve perturbation of the cell cycle distribution of Ramos cells. Furthermore rapid induction of c-fos and the decrease in c-myc observed after anti-IgM treatment are both unaltered by TNF-alpha. Our results suggest that TNF-alpha is an inhibitor of apoptosis in Ramos cells, that its overall pattern of inhibition is similar to that of anti-CD40, and that both agents act at some point distal to the alteration of c-fos and c-myc by anti-IgM.

Apoptosis↗

PubMed1996

The production of superoxide anion and nitric oxide by cultured murine leukocytes and the accumulation of TNF-alpha in the conditioned media is inhibited by taurine chloramine.

Taurine chloramine (Tau-Cl) inhibits production of nitric oxide (NO) by activated peritoneal macrophages and attenuates accumulation of tumor necrosis factor-alpha (TNF-alpha) in the culture media, similar to that previously reported for activated RAW 264.7 cells. In addition, the effect of Tau-Cl and taurine on superoxide anion (O2-) production in murine peritoneal exudate polymorphonuclear leukocytes (PMN) was examined. Tau-Cl inhibited O2- production in a manner that was dose-dependent and reversible. Taurine also inhibited O2- production by stimulated PMN, but at higher concentrations and to a lesser extent than Tau-Cl. The effects of taurine on O2- production was attributed to the in vitro formation of Tau-Cl catalyzed by PMN associated halide-dependent myeloperoxidase. In contrast, production of NO by activated peritoneal macrophages and accumulation of TNF-alpha in the media was inhibited by Tau-Cl while taurine was without effect. These data lend support to the notion that Tau-Cl may participate in the inflammatory response by modulating production of inflammatory mediators.

Animals↗

PubMed1996

Taurine chloramine inhibits prostaglandin E2 production in activated RAW 264.7 cells by post-transcriptional effects on inducible cyclooxygenase expression.

Taurine chloramine (Tau-Cl) was recently demonstrated to inhibit production of nitric oxide and tumor necrosis factor-alpha (TNF-alpha) by activated macrophages. Since increased production of prostaglandin E2 (PGE2), a reaction catalyzed by induction of cyclooxygenase-2 (COX-2), is also associated with the inflammatory response, we determined the effects of Tau-Cl on PGE2 production and on expression of COX-2 protein and COX-2 mRNA in activated RAW 264.7 cells, a murine macrophage-like cell line. Tau-Cl inhibited production of PGE2 in a concentration dependent manner with an IC50 of 0.4 mM. The decrease in PGE2 production was largely accounted for by decreased expression of COX-2 protein. Although the kinetics of COX-2 mRNA expression was altered in Tau-Cl treated cells, mRNA expression appeared to be quantitatively unimpaired. These results suggest that Tau-Cl affects the post-transcriptional regulation of COX-2 expression and support the idea that Tau-Cl may function as an inhibitory modulator of the inflammatory response.

Animals↗

PubMed1996

Normal superoxide radical production in the neuronal ceroid-lipofuscinoses.

The neuronal ceroid-lipofuscinoses (NCL) are a group of inherited progressive encephalopathies. Striking histomorphological feature of the NCL is the accumulation of storage material within the lysosomes in neural and extraneural cells. The basic underlying defect causing the disease is not known. Presupposing a disturbance in lipid peroxidation, some authors recommend antioxidant treatment to slow down the progression of the disease. In this study, the superoxide radical production of polymorphonuclear leukocytes as one potential source of reactive oxygen species was measured in this disorder for the first time. No significant difference in this production between affected individuals and healthy controls could be detected. Our findings cast doubt on the therapeutic benefit of antioxidant treatment.

Adolescent↗

PubMed1996

Effect of pentaphasic pulse sequence as an impedance sensor on standard electrocardiographic recordings.

Two advances in cardiac pacing have resulted in an internal conflict in some pacemakers. One is the development of a standard lead physiological sensor and the other is protection from electromagnetic interference (EMI). One popular type of standard lead sensor uses sub-threshold pulses to measure intracardiac and intrathoracic impedance changes, i.e., minute ventilation. Recent clinical observations and extensive in vitro testing have verified that digital cellular phones can be troublesome. Large feedthrough capacitors (FCs), effective in blocking the EMI, will preclude sensing of the standard impedance-based signals. A variety of pulse configurations were studied that might be effective for a sensor-based impedance signal while allowing the pacemaker to continue to use large Fcs protecting them from environmental EMI. In comparison to both monophasic and biphasic pulse sequences, a pentaphasic pulse sequence was effective as an impedance sensor, still allows large FCs to function as an effective filter for environmental EMI, and would not produce artifacts on surface ECG.

Cardiac Pacing, Artificial↗

PubMed1996

Gamma knife radiosurgery in children.

52 pediatric patients were treated with radiosurgery at the University of California, San Francisco. Arteriovenous malformations were treated in 27 patients. Complete obliteration was noted in 4 of 12 patients imaged more than 2 years after radiosurgery. Arteriovenous malformation rebleed was noted in 1 patient. Symptomatic T2 changes were noted in 2 patients. Among 29 neoplasms treated in 25 patients, local control was noted in 5 of 7 low-grade gliomas, 5 of 14 high-grade gliomas, 4 of 5 craniopharyngiomas and 3 of 3 sarcomas. Three patients treated for neoplasms developed necrosis after radiosurgery.

Adolescent↗

PubMed1996

Chronic conditions, physical limitations and dependency among seniors living in the community.

The majority (75%) of people aged 55 and over who live in the community, as opposed to living in long-term health care institutions, report having at least one chronic condition. However, only about one in six has some physical limitation. As well, one in six men and one in four women who live in the community need help with everyday activities such as housework or meal preparation. With advancing age, the prevalence of most chronic conditions increases, as does the prevalence of physical problems and dependency. The contribution of particular conditions to physical limitations and dependency varies. According to Statistics Canada's 1994-95 National Population Health Survey, the conditions most strongly related to physical limitations and to the need for help with activities of daily living were epilepsy and the effects of stroke, neither of which affected a large percentage of the household population aged 55 and over. By contrast, arthritis/rheumatism, non-arthritic back problems and cataracts, which were also associated with physical limitations and dependency, affected a relatively large percentage of community-dwelling seniors. This article shows the prevalence of specific chronic conditions, physical limitations and dependency among people aged 55 and over living in the community, by sex and age. Logistic regression is used to examine relationships between each chronic condition and the existence of physical limitations and dependency.

Activities of Daily Living↗

PubMed1995

Taurine chloramine inhibits production of nitric oxide and TNF-alpha in activated RAW 264.7 cells by mechanisms that involve transcriptional and translational events.

We previously reported that taurine chloramine (Tau-Cl) inhibits the production of both nitric oxide and TNF-alpha by activated RAW 264.7 cells. The current studies were conducted to gain insight into the mechanisms through which Tau-Cl exerts these effects. RAW 264.7 cells were activated by LPS (10 micrograms/ml) and rIFN-gamma (50 U/ml) in the absence or presence of either 0.8 mM Tau-Cl or taurine. Production of NO and TNF-alpha by RAW 264.7 cells was monitored: NO was measured spectrophotometrically as nitrite and TNF-alpha was measured by ELISA. Cell lysates were analyzed for the inducible form of nitric oxide synthase (iNOS) by Western blot analyses, and TNF-alpha and iNOS mRNAs were assessed by northern blot analyses. Tau-Cl inhibited transcription of the iNOS gene, or some earlier event in the signal transduction pathway, because iNOS protein and iNOS mRNA were undetected in lysates of cells activated in the continuous presence of Tau-Cl. In contrast, steady-state levels of TNF-alpha mRNA increased in the presence of Tau-Cl to at least the same extent as that in untreated activated cells and persisted for a longer period of time. Metabolic labeling experiments demonstrated that Tau-Cl inhibited translation of TNF-alpha mRNA because the presence of the presecretory 26-kDa form and the secreted 17-kDa form of TNF-alpha were greatly reduced in lysates and culture media, respectively, of cells activated in the presence of Tau-Cl. Inhibition of TNF-alpha synthesis by Tau-Cl is not the result of a generalized effect on protein synthesis because the amount of radiolabeled protein precipitated from metabolically labeled cells by TCA was unaffected by Tau-Cl, and cell viability was unaffected. The results of these studies demonstrate that Tau-Cl decreases production of tissue-damaging inflammatory mediators and thus may act as a physiologic modulator of macrophage function.

Amino Acid Oxidoreductases↗

PubMed1995

Adaptive filtering of the electromyographic signal for prosthetic control and force estimation.

An adaptive time constant filter is derived for electromyographic (EMG) signal processing in prosthetic control applications. The analysis indicates that the mean-squared estimation error can be reduced by varying the time constant of the filter as a function of the signal and its derivative. Results of several experiments indicated this filter provides faster response and smaller estimation error than several previously available filters.

Algorithms↗