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Biomedical subjects

E Park

Publications and source records attributed to E Park.

At least 91 records · Page 5Linked to original sources
PubMed1995

Beliefs, knowledge, and behavior about cancer among urban Hispanic women.

As part of a cancer prevention program aimed at minority and disadvantaged urban women, cancer beliefs, knowledge, and behaviors were assessed among home-health attendants in the Bronx, N.Y. Information, was gathered from 876 Hispanic women who comprised 62% of the female home-attendant study population from whom data were collected (n = 1413). Of these women, 82% (n = 718) were Spanish speaking and 18% (n = 158) were English speaking as defined by their choice to complete the survey questionnaire in Spanish or English. As a whole, the population reported high levels of obtaining screening tests and engaging in preventive behaviors. However, nearly 60% did not know what cervical cancer was. The most important predictor of inadequate cancer screening was lack of knowledge. Large numbers of women subscribed to cancer misconceptions, such as the belief that bumps or bruises cause cancer. Fifty-eight percent believed that surgery causes cancer to spread, a belief that may prevent a woman with breast cancer from undergoing early intervention procedures, such as lumpectomy. This survey indicated that Hispanic women in our population engaged in relatively high levels of cancer preventive behaviors, even though their knowledge base was limited. Many of them hold misperceptions about cancer that can have an impact on preventive behaviors. We conclude that cancer prevention programs targeting the Hispanic populations should emphasize the provision of factual information about cancer and cancer-screening behaviors in the context of an exploration of inaccurate beliefs about cancer that may inhibit preventive health behaviors.

Adult↗
PubMed1994

Taurine protects against oxidant-induced lung injury: possible mechanism(s) of action.

It is thought that oxidant-induced tissue damage is not a direct effect of the oxidant per se, but rather results from the inflammatory response that occurs thereafter. As a result of inflammation following oxidant exposure, there are neutrophils, monocytes, and macrophages with myeloperoxidase-H2O2-halide activity in the lung. Leukocytes and especially neutrophils contain high intracellular concentrations (22-50mM) of taurine (6, 8, 11, 20). Taurine acts as a trap for toxic hypochlorous acid (HOCl) and forms the less reactive metabolite, N-chlorotaurine (5-6). Thus, the biological activity of halide-dependent myeloperoxidase may be regulated by endogenous taurine. Although taurine had no effect in the present study, polymorphonuclear leukocytes have an active myeloperoxidase system capable of producing N-chlorotaurine (9, 19) and would be present at the site of inflammation in oxidant-exposed lungs. Our data suggest that taurine via N-chlorotaurine formation may protect the lung from oxidant injury, at least in part, by inhibiting production of nitrite and TNF-alpha. Moreover, lavage cells isolated from rats pretreated with taurine and exposed to O3 have a significant decrease in the production of nitrite and TNF-alpha, compared with lavage cells from rats exposed to O3 without taurine supplementation (preliminary studies). Both the concentration of taurine and the effects of N-chlorotaurine strengthen the potential impact of this chlorinated amine in vivo. N-Chlorotaurine may protect against oxidant-induced lung injury by inhibiting production of nitrite and the release of TNF-alpha which are both known to be directly linked to tissue injury.

Amino Acid Oxidoreductases↗
PubMed1994

Tin-mediated heme oxygenase gene activation and cytochrome P450 arachidonate hydroxylase inhibition in spontaneously hypertensive rats.

The effect of SnCl2 on the transcription of the heme oxygenase gene in spontaneously hypertensive rats was examined using cDNA for the rat heme oxygenase (HO-1). An increase in renal HO-1 mRNA levels was observed in response to SnCl2 treatment. Quantitative evaluation by scanning densitometry demonstrated a maximal increase in HO-1 mRNA 24-fold over control at 8 hours after SnCl2 administration. Nuclear runoff assay using isolated renal nuclei from SnCl2-treated rats revealed an active HO-1 gene transcription. Transcription of HO-1 in rat kidney was greatly increased within 3 hours of administration of SnCl2, as evidenced by the level of [alpha 32P]UTP incorporation into nuclear RNA. As a consequence of activation of the HO-1 gene transcription, renal enzyme activity increased eightfold at 16 hours after SnCl2, and reached maximal activity of 16-fold over control at 32 hours after injection. No significant change in cytochrome P450 fatty acid omega-hydroxylase (P450 4A) mRNA was observed after SnCl2 administration. Cytochrome P450-arachidonic acid omega/omega-1 hydroxylase(s) activity (formation of 20- and 19-HETE) was significantly reduced 24 hours after SnCl2 administration and remained lower than the control level 48 and 72 hours after injection. In addition, blood pressure was reduced from 151 +/- 2.5 mm Hg to 133 +/- 2.3 mm Hg after 48 hours of SnCl2 treatment. The reduction in blood pressure preceded natriuresis. It is concluded that SnCl2 induces activation of the HO-1 gene, which is followed by elevation in enzyme activity and a decrease in cytochrome P450-arachidonic acid omega-hydroxylase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Mycobacterial lipoarabinomannan induces nitric oxide and tumor necrosis factor alpha production in a macrophage cell line: down regulation by taurine chloramine.

Avirulent mycobacterium H37Ra lipoarabinomannan (LAM) elicited nitric oxide (NO) and tumor necrosis factor alpha in a dose-dependent manner in a murine macrophage cell line, RAW 264.7 cells. H37Ra LAM and recombinant gamma interferon were highly synergistic for NO production. The production of NO and the release of tumor necrosis factor alpha stimulated by H37Ra LAM plus recombinant gamma interferon in RAW 264.7 cells are inhibited by taurine chloramine.

Animals↗
PubMed1994

Age differences of married and divorcing couples.

This paper analyzes the probability of a married couple getting divorced, based on the age difference between the husband and wife. To calculate such probabilities, the distribution of age differences of married couples was derived from the 1991 Census and the 1990 General Social Survey, and the distribution of age differences of divorcing couples was obtained from 1991 divorce data provided by the Department of Justice Canada. These distributions, the first based on data that are seldom available, are also analyzed in this paper. The results provide details about the expected significant imbalances that exist, both for married and divorcing couples, between the number of couples with older husbands and the number with older wives. A model is developed that shows that divorce rates are lowest when the husband is two to ten years older than the wife or when the magnitude of their age difference is extremely large. Furthermore, the chance of divorce is much higher when the wife is older than the husband than vice versa. The demands on a younger spouse--usually the wife--to provide informal health care for an older spouse are briefly discussed.

Adolescent↗
PubMed1993

Taurine chloramine inhibits the synthesis of nitric oxide and the release of tumor necrosis factor in activated RAW 264.7 cells.

Taurine is present in high concentrations in most mammalian tissues, including those that prodigiously produce oxidants. Taurine protects against bronchiolar damage induced by NO2, ozone, bleomycin, and amiodarone. Taurine is chlorinated to form taurine chloramine (Tau-Cl) by the halide-dependent myeloperoxidase system and, under physiological conditions, reduces HOCl toxicity. Although NO and its metabolites, NO2- and NO3-, are thought to be major mediators of tissue damage resulting from oxidant exposure, cytokines, including tumor necrosis factor (TNF), are also involved. We examined the effects of Tau-Cl on NO production and TNF release by using RAW 264.7 cells activated with recombinant interferon-gamma (rIFN-gamma; 50 U/ml) and lipopolysaccharide (LPS; 10 micrograms/ml). NO was measured spectrophotometrically as NO2- after reaction with Griess reagent and TNF was measured by ELISA. Tau-Cl (0.5 mM) inhibits NO and TNF released into the medium by 47% and 43%, respectively. Tau-Cl is actively transported into RAW 264.7 cells by an uptake system that is energy, temperature, and Na+ dependent. Competition experiments demonstrate that the uptake system for Tau-Cl is distinct from that for taurine. In addition, the NO synthase activity of cytosolic preparations from activated RAW 264.7 cells is irreversibly inhibited by pretreatment with Tau-Cl. We demonstrate that Tau-Cl inhibits production of NO and TNF by activated macrophages and suggest a mechanism through which taurine supplementation may protect against oxidant-induced tissue damage.

Amino Acid Oxidoreductases↗
PubMed1993

The Saccharomyces cerevisiae DNA repair gene RAD25 is required for transcription by RNA polymerase II.

The RAD25 gene of Saccharomyces cerevisiae is required for excision repair of ultraviolet-damaged DNA and, in addition, is essential for viability. RAD25 shares a high degree of homology with the human ERCC3/XPBC-encoded protein, and the yeast and human proteins resemble one another in containing the conserved ATPase/DNA helicase sequence motifs. To determine the nature of the essential role of RAD25, we have isolated a recessive temperature-sensitive conditional lethal mutation of the gene and have examined its effect on transcription. Upon shift to the nonpermissive temperature, the rad25 temperature-sensitive (ts) mutant stops growth rapidly and shows a large decrease in the synthesis of poly(A)+ RNA. Transcription of a large number of yeast genes, including HIS3, TRP3, STE2, MET19, RAD23, CDC9, and ACT1 is inhibited at the restrictive temperature in the rad25 ts mutant, and the galactose-inducible synthesis of GAL7 and GAL10 mRNAs is also severely affected by the loss of RAD25 activity. These findings implicate a general requirement of RAD25 in RNA polymerase II transcription.

Amino Acid Sequence↗
PubMed1993

Fatigue compensation of the electromyographic signal for prosthetic control and force estimation.

During a sustained muscle contraction, the amplitude of electromyographic (EMG) signals increases and the spectrum of the EMG signal shifts toward lower frequencies. These effects are due to muscular fatigue and can cause problems in the control of myoelectric prostheses and in the estimation of contraction level from the EMG signal. It has been well known that the fatigue effects can be explained by the conduction velocity changes during the fatigue process and by the idea that the conduction velocity is linearly proportional to the median frequency of EMG signals. Hence the fatigue process can be monitored by measuring the median frequency. A fatigue compensation preprocessor has been developed. It uses the widely accepted power spectrum density model of EMG signals that contains the conduction velocity as a measure of fatigue. It was verified that the preprocessor scales down the amplitude of the fatigued EMG signal and decompresses the spectrum. Hence, the preprocessor eliminates the increase in amplitude and the shift in frequency and enables consistent EMG signals to be used to control prostheses.

Artificial Limbs↗
PubMed1993

Antigenic heterogeneity of Qa-2 antigens in C57BL/6.

The Qa-2 antigens are class I-like molecules encoded by genes mapped telomeric to the H-2D region on chromosome 17 in the mouse. A panel of 8 new monoclonal anti-Qa-2 antibodies derived from a C3H.KBR anti-C3H. SW immunization was studied. Immunoprecipitation of 125I-labeled C57BL/6 splenocyte antigens showed that all of these antibodies precipitated 40 kDa molecules which could be completely precleared by the monoclonal antibody 20-8-4, which had previously been shown to crossreact with Qa-2. One of the monoclonal antibodies (1-12-1), however, was found not to completely preclear Qa-2 antigens precipitable by the other 7 antibodies or by 20-8-4, suggesting the existence of at least two different species of Qa-2 molecules. Cell lines transfected with Q7 or Q9 genes were reactive with all 9 antibodies and the Qa-2 antigens expressed on surface membranes of these cells were completely precleared by both 20-8-4 and 1-12-1. Therefore, the observed heterogeneity of these molecules cannot be explained by an antigenic difference between the Q7 and Q9 gene products. 2D gel analyses showed identical pI spectra between Qa-2 molecules precipitated with 20-8-4 and 1-12-1. In addition, all of the monoclonal antibodies reacted with labeled antigen preparations following treatment with Endo F or neuraminidase, indicating that carbohydrate moieties are probably not responsible for the antigenic difference between the two species of Qa-2 antigen.

Animals↗
PubMed1993

A simple hindlimb suspension apparatus.

This paper describes the assembly of a simple, inexpensive apparatus for application of the hindlimb suspension model to studies of the effects of unloading on mammalian physiology. Construction of a cage and suspension assembly is described using materials that can be obtained from most hardware stores. The design is kept simple for easy assembly and disassembly to facilitate cleaning and storage. The suspension assembly allows the animals full access to all portions of the floor area and provides an effective environment to study the effects of unloading.

Animals↗
PubMed1992

RAD25 (SSL2), the yeast homolog of the human xeroderma pigmentosum group B DNA repair gene, is essential for viability.

Xeroderma pigmentosum (XP) patients are extremely sensitive to ultraviolet (UV) light and suffer from a high incidence of skin cancers, due to a defect in nucleotide excision repair. The disease is genetically heterogeneous, and seven complementation groups, A-G, have been identified. Homologs of human excision repair genes ERCC1, XPDC/ERCC2, and XPAC have been identified in the yeast Saccharomyces cerevisiae. Since no homolog of human XPBC/ERCC3 existed among the known yeast genes, we cloned the yeast homolog by using XPBC cDNA as a hybridization probe. The yeast homolog, RAD25 (SSL2), encodes a protein of 843 amino acids (M(r) 95,356). The RAD25 (SSL2)- and XPBC-encoded proteins share 55% identical and 72% conserved amino acid residues, and the two proteins resemble one another in containing the conserved DNA helicase sequence motifs. A nonsense mutation at codon 799 that deletes the 45 C-terminal amino acid residues in RAD25 (SSL2) confers UV sensitivity. This mutation shows epistasis with genes in the excision repair group, whereas a synergistic increase in UV sensitivity occurs when it is combined with mutations in genes in other DNA repair pathways, indicating that RAD25 (SSL2) functions in excision repair but not in other repair pathways. We also show that RAD25 (SSL2) is an essential gene. A mutation of the Lys392 residue to arginine in the conserved Walker type A nucleotide-binding motif is lethal, suggesting an essential role of the putative RAD25 (SSL2) ATPase/DNA helicase activity in viability.

Amino Acid Sequence↗
PubMed1992

Detection of Fc receptors for IgA on rat alveolar and peritoneal macrophages.

The presence of Fc receptors for IgA on alveolar macrophages was determined by rosette assay and immunogold labeling. IgA-mediated phagocytosis by alveolar macrophages was observed. Results of these assays were compared between rats receiving no treatment and those receiving long-term cortisone administration. Sheep erythrocytes coated with dextran and an IgA monoclonal antibody specific for the alpha 1,3 linkages of dextran bound to 16% of alveolar macrophages. However, peritoneal macrophages did not form rosettes with dextran-IgA-coated erythrocytes. Immunogold labeling by transmission electron microscopy revealed that most Fc receptors for IgA were found on the membrane of pseudopodia of activated alveolar macrophages. Long-term cortisone administration diminished the phagocytosis and phagocytic index of alveolar macrophages, thereby contributing to decreased host resistance to infection (e.g., Pneumocystis carinii pneumonia).

Animals↗
PubMed1988

Hormonal regulation of chimeric genes containing the phosphoenolpyruvate carboxykinase promoter regulatory region in hepatoma cells infected by murine retroviruses.

Hepatoma cells were infected with replication-incompetent murine retroviruses containing the selectable gene for amino-3'-glycosyl phosphotransferase (neo) and/or the nonselectable gene for bovine growth hormone (bGH). Expression of these genes was controlled by the promoter regulatory region of the gene for the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) from the rat, which contains hormone and tissue-specific regulatory elements. Expression of the transduced PEPCK-neo gene was stimulated by Bt2cAMP and glucocorticoids and inhibited by insulin. The amount of RNA which initiated within the retroviral 5' long terminal repeat (5' LTR) was inhibited when internal promoters were present in the retroviral vector. When no internal promoter was present, expression from the 5' LTR was higher and stimulated by glucocorticoids, due to the presence of a glucocorticoid regulatory element in the 5' LTR. Infection of cells with retroviruses altered the basal expression and hormonal regulation of the endogenous PEPCK gene, but had no effect on the expression of the tyrosine aminotransferase gene, which is regulated in a similar manner by cAMP and glucocorticoids. A segment of the PEPCK promoter acted as a hormonally regulated enhancer, bringing the SV40 early promoter under the control of Bt2cAMP. A second, nonselectable gene (PEPCK-bGH), contained in the retroviral vector together with PEPCK-neo, was expressed and regulated appropriately when introduced into hepatoma cells. The proviruses were initially integrated randomly into the host cell genome, but after prolonged selection for expression of the transduced PEPCK-neo gene, cells were selected which contain a predominant site(s) of integration. Among populations of cells, however, the predominant site(s) of proviral integration was different. The selection of cells with a specific site of integration from a population was accelerated by the presence of PEPCK promoter sequences in the provirus. Despite the need to better characterize their effects on the host cell, retroviruses appear to be versatile tools for the specific introduction of regulated genes into cells.

Animals↗
PubMed1988

Tissue-specific expression and dietary regulation of a chimeric phosphoenolpyruvate carboxykinase/bovine growth hormone gene in transgenic mice.

A series of transgenic mice was produced by microinjection of a segment of DNA, containing 460 base pairs of the phosphoenolpyruvate (P-enolpyruvate) carboxykinase promoter-regulatory region ligated to the bovine growth hormone structural gene, into the male pronucleus of fertilized mouse eggs. Founder animals which contained the gene were selected for further analysis and for breeding. The concentration of bovine growth hormone in the serum of animals which were shown to contain the gene ranged from a low of 5 ng/ml serum to approximately 2300 ng/ml serum. Mice with high levels of bovine growth hormone had growth rates double that of their litter mates which did not contain the transgene. The transgene was expressed only in the liver and kidney of the animals studied, and the level of specific mRNA for bovine growth hormone in these tissues could be regulated by diet in a manner similar to the endogenous P-enolpyruvate carboxykinase gene. Feeding the animals a diet high in carbohydrate for 1 week caused a 90% decrease in the concentration of bovine growth hormone in the blood, suggesting that the expression of the chimeric P-enolpyruvate carboxykinase/bovine growth hormone gene is sensitive to insulin. When the same animals were then refed a diet high in protein, but devoid of carbohydrate, the concentration of bovine growth hormone in their blood was induced 30-fold within a week. The administration of dibutyryl cyclic AMP to the transgenic mice caused a 2-fold induction in the level of bovine growth hormone in the serum within 90 min. Thus the region between -460/+73 in the P-enolpyruvate carboxykinase promoter-regulatory region contains sequences which can direct the tissue-specific expression, as well as hormonal and dietary responsiveness, of a linked structural gene.

Amino Acid Sequence↗