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Referral patterns and exercise response in the rehabilitation of female coronary patients aged greater than or equal to 62 years.

Gender-related differences in cardiac rehabilitation referral patterns and response to an aerobic conditioning program were examined in 226 hospitalized older coronary patients (aged greater than or equal to 62 years). Overall, the outpatient cardiac rehabilitation participation rate in this population was 21%. Older women were less likely to enter cardiac rehabilitation than were older men (15 vs 25%; p = 0.06), despite similar clinical profiles. This was explained primarily by a greater likelihood of primary physicians to strongly recommend cardiac rehabilitation to men. Before conditioning, women who entered cardiac rehabilitation were less fit than were men; peak oxygen consumption was 18% lower in women (16 +/- 5 vs 20 +/- 5 ml/kg/min; p = 0.02). However, both groups improved aerobic capacity similarly in response to a 12-week aerobic conditioning program, with maximal oxygen consumption increasing by 17% in women and by 19% in men. Thus, older female coronary patients are less likely to be referred for cardiac rehabilitation, despite a similar clinical profile and improvement in functional capacity from the training component.

Age Factors↗

Isolation of intact polysomes from mechanically dehulled developing grain.

A rapid method for obtaining large quantities of developing groats suitable for the isolation of highly intact polysomes has been developed. Developing spikelets were harvested directly from oat panicles into liquid nitrogen and then quickly passed through a dehuller. Chaff was removed by air aspiration and the resultant groats were collected directly back into liquid nitrogen. Approximately 250 g of groats could be isolated each man-hour by the above method. In comparison, only 10 g of endosperm could be collected by squeezing it out of spikelets using an endosperm mangle. Membrane-bound polysomes extracted from the immature groats were compared to those extracted from endosperm. The largest polysomes discernable as unique peaks on sucrose gradients were ten-mers and nine-mers for groats and endosperm, respectively. Polysomes isolated from both starting materials stimulated similar incorporations of [35S]methionine into trichloroacetic acid-insoluble products during in vitro translations in wheat germ extract. Both polysome preparations directed the synthesis of similar high-molecular-weight proteins. Based on these criteria, polysomes from both preparations were found to be of similar intactness, although the groat starting material was much more readily obtained. The polysome classes having the maximum absorbance peak for endosperm and groat polysomes were six-mers and eight-mers, respectively.

Cell Fractionation↗

Biogenesis of embryonic chick liver delta-aminolevulinate synthase: regulation of the level of mRNA by hemin.

The effects of hemin on the concentration of the mRNA for delta-aminolevulinate synthase (ALA synthase) and on the association of the messenger with polysomes were investigated in primary cultures of embryonic chick hepatocytes incubated with allylisopropylacetamide (AIA). A synthetic 24-mer DNA complementary to ALA synthase mRNA was used to determine by solution hybridization the effects of AIA and of AIA plus hemin on the ALA synthase-specific RNA sequences in the cells. The results indicated that ALA synthase mRNA concentrations increased significantly in hepatocytes incubated for 5 h with AIA (0.075 mg/ml), and that hemin in the medium (2 or 10 microM) blocked the increase in the messenger. When delta-aminolevulinic acid (ALA) and FeCl3 were added into the culture medium (1 mM and 5 microM, respectively), the increase in ALA synthase mRNA brought on by AIA was also inhibited. Neither ALA nor FeCl3, when individually added to the cultures, was as effective as the combination of the two. The results with ALA + FeCl3 suggested that stimulation of intracellular production of heme was also effective in blocking the increase in ALA synthase mRNA caused by AIA. Finally, the distributions of ALA synthase mRNA were compared in polysomes isolated from hepatocytes which had been incubated with AIA for 5 h in the presence and absence of 10 microM hemin in the medium. Although a drop was detected in the concentration of ALA synthase mRNA in polysomes from hepatocytes incubated with hemin for 30 min, the decrease was explained by the effect of hemin on the mRNA concentration in the cells.

5-Aminolevulinate Synthetase↗

The helical content of zein, a water insoluble protein, in non-aqueous solvents.

The conformation of zein, a seed protein from corn, was determined by optical rotary dispersion measurements in a wide variety of nonaqueous solvents. Over a wide range of dielectric constants, in pure and mixed solvent systems, the helical content was independent of dielectric constant. Determination of the helical content of insulin and ribonuclease in several of these solvents indicated a variation in secondary structure comparable of that of zein. Though virtually insoluble in water, zein not only is a globular protein in nonaqueous solutions, but has conformational properites characteristic of more conventionally behaving globular proteins.

Acetamides↗

Biogenesis of mitochondrial proteins regulation of maturation of delta-aminolevulinate synthase by hemin.

The effect of hemin on the biogenesis of delta-aminolevulinate (ALA) synthase was examined in primary cultures of chick embryo hepatocytes. Hemin (0.010 mM) in the culture medium significantly inhibited the induction of ALA synthase activity in hepatocytes exposed to the porphyrogenic agent allylisopropylacetamide. In hepatocytes pulse-labeled with [35S]methionine for 45 min in the presence and absence of hemin, it was determined by immunechemical analyses that hemin blocked the processing of the precursor of ALA synthase.

5-Aminolevulinate Synthetase↗

Regulation of production of embryonic chick liver delta-aminolevulinate synthase: effects of testosterone and of hemin on the mRNA of the enzyme.

The effects of testosterone and of hemin on the concentration of the mRNA of embryonic chick liver ALA synthase were investigated. Using cDNA-RNA liquid hybridization analyses, we determined that testosterone, when injected into the fluid surrounding chick embryos, caused a dose-dependent increase in the concentration of ALA synthase mRNA in liver. Similarly, addition of testosterone (5 micrograms/ml) or of 75 micrograms/ml of allylisopropylacetamide (AIA) into the medium of chick embryo hepatocytes maintained in culture caused an increase in the concentration of ALA synthase mRNA. Hemin (2 or 5 microM), when added to the culture medium, inhibited the elevations of ALA synthase mRNA concentration brought on by testosterone and by AIA.

5-Aminolevulinate Synthetase↗

Regulation of the stability of chicken embryo liver delta-aminolevulinate synthase mRNA by hemin.

The effect of hemin on the stability of delta-aminolevulinate (ALA) synthase mRNA was investigated in primary cultures of chicken embryo hepatocytes. Hepatocytes were first incubated with allylisopropylacetamide (AIA) to increase the starting level of ALA synthase mRNA, and then the cells were incubated with alpha-amanitin (1 microgram/ml) to block further transcription of ALA synthase RNA. The rates of depletion of the enzyme's mRNA were then determined by liquid hybridization analyses in cells incubated with or without hemin (10 microM) in the culture medium. The analyses indicated that hemin increased the rate of ALA synthase mRNA degradation. The half-life of the messenger in hepatocytes incubated with hemin was 80 min compared with 220 min in cells incubated without additional hemin in the culture medium. The results thus indicated a novel mechanism by which hemin modulated the biogenesis of ALA synthase in liver.

5-Aminolevulinate Synthetase↗

Thyroid hormone modulates apolipoprotein B gene expression in HepG2 cells.

We have investigated the modulation of apolipoprotein B gene expression in HepG2 cells by thyroid hormone. ApoB secretion rate in serum-free media was found to be significantly increased in the presence of the hormone in long-term cultures (48 h, 37%). This stimulatory effect was dose-dependent. The mechanisms underlying the stimulatory effect of triiodothyronine on apoB production were investigated. Triiodothyronine increased apoB mRNA levels by about 25-36% as determined by slot- and Northern-blot analysis of total RNA. ApoB synthesis rate was also found to be increased both in in vivo pulse-chase experiments (61%) and in in vitro translation studies (54.5%). Despite the 54.5-61% increase in apoB synthesis with triiodothyronine, only a 30% increase in apoB secretion was noted suggesting that part of the increase in the intracellular apoB pool may be lost by degradation. Overall, apoB gene expression appears to be modulated by thyroid hormone at both transcriptional and posttranscriptional levels.

Apolipoproteins B↗

Identification of functional subpopulations of murine natural killer cells based on their cell surface asialo GM1 phenotype.

HSV-1 infection renders a mouse fibroblast cell line (MCN) sensitive to murine splenic NK killing which is independent of interferon (IFN) induction during the assay. This NK (HSV-1) activity is distinctive from conventional NK (YAC-1) in that they cannot be aborted by anti-asialo GM1 (anti-ASGM1) antibody plus complement treatment as NK (YAC-1) does. Further characterization of these two subpopulations was carried out by fluorescence-activated cell sorting (FACS) technique based on their cell surface asialo GM1 (ASGM1) phenotype. While almost all NK (YAC-1) activity resides within FACS-positive population, both ASGM1 positive and negative cell populations can kill the virally infected MCN equally well. One interesting observation is that only the ASGM1 positive cells respond significantly to IL-2 NK boosting. Five different mouse strains (CD-1, C57BL/6J, C57BL/6J-BG, SM/J, and SJL) were compared on their FACS profile with anti-ASGM1 antibody as well as their NK function. The differences observed are discussed.

Animals↗

Natural cytolytic activity in mice with natural or induced cellular defects. I. Differential ability of in vitro interleukin-2 addition to augment natural cytolytic function.

The ability of in vitro addition of recombinant interleukin 2 (rIL-2) to differentially enhance natural cytotoxicity was assessed using cells from mice with natural and induced cellular defects. In vivo treatment with most immunosuppressive or cytoreductive agents, anti-asialo-GM1 antibody, or gamma irradiation dramatically reduced in vitro cytotoxicity against natural killer (NK) sensitive targets by direct reduction in either percentage specific lysis or lytic units per spleen. In most cases, in vitro addition of rIL-2 (at concentrations causing augmented NK function in cells from naive Balb/C mice) enhanced cytotoxic activity of cells from treatment groups to a normal value but not within the rIL-2-enhanced range of nontreated animals. Additionally, cytotoxic activity of cells from animals treated with certain drugs or gamma irradiation could be augmented by rIL-2 when measured by percentage lysis but not lytic units per spleen. In vivo treatment with cyclosporin A did not affect natural cytotoxic activity and addition of rIL-2 augmented the NK activity in a similar fashion to the profile of naive cells. In experiments using cells from beige (C57Bl/6-bg) mice which have a natural defect in NK activity against YAC-1 targets, addition of rIL-2 (at concentrations causing augmented natural cytotoxic function in cells from C57Bl/6 mice) could not effectively enhance in vitro natural cytotoxic function.

Adjuvants, Immunologic↗

Apolipoprotein B gene polymorphism and plasma lipids and lipoproteins in a Canadian Caucasian population.

We have investigated the frequency of Hind III DNA polymorphism of the human apolipoprotein B gene in a Canadian Caucasian population with coronary artery disease, as documented by angiography, and a healthy control population. Patients had significantly (p < 0.05) higher levels of cholesterol, triglycerides, LDL-cholesterol, apolipoprotein B, and lower level of apoAI compared to the controls. Restriction fragment-length polymorphism analysis detected nine hybridizable fragments denoted as H1 to H9. The H1, H2, H3, and H7 alleles were polymorphic. The [H4-H9] genotype seems to be the normal genotype within the population studied since it was detected in 69% of the control group. The [H1-H9] genotype was most frequently observed in the patients (frequency = 0.68). We were unable to strongly associate any of the alleles or genotypes detected with the changes in lipids. The additional alleles observed in the patient group may indicate possible mutations at the 3' end of the apolipoprotein B gene locus.

Adult↗

Human bioassays to assess environmental genotoxicity: development of a DNA repair assay in HepG2 cells.

A direct assessment of the effects of environmental chemicals on human health has been hampered by the lack of suitable experimental systems. We have recently employed a human liver cell line (HepG2) to assess the biological effects of pollutants at both cellular and DNA levels. A Neutral Red dye uptake assay was used to assess potential cytotoxic effects of xenobiotics. DNA damage was quantified using an unscheduled DNA synthesis assay that measures repair that is induced following exposure to genotoxic compounds. HepG2 cells responded to the known mutagens, 4-nitroquinoline N-oxide and methylmethane sulfonate, both in the Neutral Red assay for cytotoxicity and two DNA repair assays for genotoxicity (monitored autoradiographically or by liquid scintillation counting). The HepG2 DNA repair and cytotoxicity assays also responded to an extract (containing polycyclic aromatic hydrocarbons) of sediment obtained from a polluted site in the Great Lakes. Results indicate that this system can be deployed further to assess potential cyto- and genotoxicity of pollutants. The development of human cell culture assays is a critical step towards a full assessment of the risk that such pollutants pose to human health.

4-Nitroquinoline-1-oxide↗

Human bioassays to assess environmental genotoxicity: development of a DNA break bioassay in HepG2 cells.

OBJECTIVES: Increasing interest in environmental health issues has created a demand for improved methods for the assessment of pollutant effects on humans. Our laboratory has developed an in vitro assay for the quantification of genotoxicity, monitored as DNA single strand breaks (SSB), in the HepG2 human hepatoma cell line. DESIGN AND METHODS: This assay procedure, which is based upon alkaline unwinding and hydroxylapatite DNA chromatography, is both rapid and simple to perform. RESULTS: HepG2 cells responded to the standard mutagen, 4-nitroquinoline N-oxide, demonstrating SSB formation at concentrations above 0.1 mumol/L. Phenanthrene-9,10-quinone, a component of diesel exhaust, mediated SSB formation at concentrations above 250 nmol/L. Finally, an extract of contaminated sediment from the Great Lakes Basin mediated SSB formation in a dose-dependent manner. CONCLUSIONS: These results illustrate the utility of this human genotoxicity assay for future use in screening of environmental pollutants.

4-Nitroquinoline-1-oxide↗