Promoting Smoke-Free Homes: A Novel Behavioral Intervention Using Real-Time Audio-Visual Feedback on Airborne Particle Levels

Interventions are needed to protect the health of children who live with smokers. We pilot-tested a real-time intervention for promoting behavior change in homes that reduces second hand tobacco smoke (SHS) levels. The intervention uses a monitor and feedback system to provide immediate auditory and visual signals triggered at defined thresholds of fine particle concentration. Dynamic graphs of real-time particle levels are also shown on a computer screen. We experimentally evaluated the system, field-tested it in homes with smokers, and conducted focus groups to obtain general opinions. Laboratory tests of the monitor demonstrated SHS sensitivity, stability, precision equivalent to at least 1 µg/m³, and low noise. A linear relationship (R² = 0.98) was observed between the monitor and average SHS mass concentrations up to 150 µg/m³. Focus groups and interviews with intervention participants showed in-home use to be acceptable and feasible. The intervention was evaluated in 3 homes with combined baseline and intervention periods lasting 9 to 15 full days. Two families modified their behavior by opening windows or doors, smoking outdoors, or smoking less. We observed evidence of lower SHS levels in these homes. The remaining household voiced reluctance to changing their smoking activity and did not exhibit lower SHS levels in main smoking areas or clear behavior change; however, family members expressed receptivity to smoking outdoors. This study established the feasibility of the real-time intervention, laying the groundwork for controlled trials with larger sample sizes. Visual and auditory cues may prompt family members to take immediate action to reduce SHS levels. Dynamic graphs of SHS levels may help families make decisions about specific mitigation approaches.     

Plasmid stability ofBacillus thuringiensis var.kurstaki (HD-1) during continuous phased cultivation

Summary Bacillus thuringiensis var.kurstaki (HD-1)_was grown as a continuous phased culture in a cyclone fermentor. During the time course of the continuous phased cultivation (CPC), the culture was sampled to determine the efficiency of sporulation and parasporal crystal formation. Concurrently, plasmid DNA was extracted and resolved on agarose gels. The plasmid profile remained constant throughout 328 h of cultivation. However, during the same time period, asporogenous, acrystalliferous variants increased from<1% to>90% of the cells harvested. Our data suggests that the disappearance of parasporal crystals inB. thuringiensis var.kurstaki (HD-1) during CPC occurs independent of plasmid copy but may be due to defective sporulation.     

Analysis of teleost hemoglobin by Adair and Monod-Wyman-Changeux models

Summary The allosteric effects of the erythrocytic nucleoside triphosphates (NTP) and of proton concentrations were investigated by precise measurement of Hb–O₂ equilibria of tench hemoglobin (including extreme, high and low saturation ranges) and analysed in terms of the MWC two state model and the Adair four step oxygenation theory.At low concentrations (NTP/Hb ratio=1.0, and pH>7.3) ATP, GTP and protons decrease Hb–O₂ affinity by increasing the allosteric constantL and reducingK _T, the association constant¹ of the deoxy, tense state of the Hb, without significantly affecting that (K _R) of the oxy state, increasing the free energy of cooperativity (G). High concentrations of these effectors, however, also reduceK _R. The greater sensitivity of the half-saturation O₂ tension (P ₅₀) of the Hb to GTP than to ATP at the same concentration, correlates with greater effects of GTP on bothK _T andK _R. The pH and NTP dependence of the four Adair association constants and the calculated fractional populations of Hb molecules in different stages of oxygenation show that the autochthonous NTP effectors and protons stabilize the T structure and postpone the TR transition basic to cooperativity in fish Hb.The possible implications of the findings for aquatic respiration are discussed.Abbreviations ATP adenosine triphosphate - DPG 2,3-diphosphoglycerate (glycerate-2,3-bisphosphate) - GTP guanosine triphosphate - IHP inositol hexaphosphate - NTP nucleoside triphosphates In this paperK _T andK _R are defined as theassociation equilibrium constants instead of dissociation constants (as originally defined by Monod et al. 1965) to facilitate comparison with the Adair constants     

Thermodynamic analysis of precisely measured oxygen equilibria of tench (Tinca tinca) hemoglobin and their dependence on ATP and protons

Summary Precise oxygen equilibria including extreme, high and low saturation values were determined for hemoglobin (Hb) from the freshwater teleostTinca tinca at three temperatures, each at two pH levels and in the presence and absence of the erythrocytic cofactor ATP, at twofold molar excess over Hb.Analysis of the data in terms of Adair's successive oxygenation theory shows that in the absence of ATP, each of the four oxygenation steps are exothermic, but that net heat release decreases as pH falls from 8.2 to 7.4. ATP greatly depresses the temperature sensitivity of oxygenation particularly at physiological erythrocytic pH, where endothermic cofactor dissociation finds expression in a reverse temperature sensitivity for binding of the 3^rd oxygen molecule to the tetrameric Hb.Enthalpy (H _i) and entropy (S _i) changes of oxygenation vary with oxygenation step, i, as well as with pH and ATP addition, but the variations of H _i are similar to those of S _i reflecting enthalpy-entropy compensation.The data show that the cooperative effects in tench Hb can be dominated either by entropic or enthalpic contributions, depending on the experimental condition and the oxygenation step.     

Androgenic regulation of hepatic gene expression

Androgen-dependent synthesis of alpha 2u globulin in the rat liver has been used in our laboratory as a model for studying the effect of sex hormones on hepatic gene expression. alpha 2u Globulin is a group of low molecular weight (Mr approximately 18,000) male specific urinary proteins synthesized and secreted by hepatocytes. In the male rat hepatic synthesis of alpha 2u globulin begins at puberty (approximately 40 days), reaches a peak level (approximately 20 mg/day) at about 75 days and declines during old age. Androgens can induce alpha 2u globulin in ovariectomized female rats in vivo and in the liver perfusion system in vitro. However, both prepubertal and senescent (greater than 800 days) male rats not only do not produce alpha 2u globulin but are also refractory to androgen administration. alpha 2u Globulin is coded by a multigene family comprising about 20-30 gene copies per haploid genome. All of these gene copies seem to express translationally active mRNAs giving rise to individual isoforms of alpha 2u globulin. Appearance and disappearance of the cytoplasmic androgen-binding protein (CAB) correlates with the androgen responsiveness of hepatocytes. Photoaffinity labeling of the hepatic cytosol shows that the biologically active binding protein, found in the cytosol of the mature male rat liver, has a molecular weight of 31 kDa. A molecular transition of the 31-kDa CAB to a biologically inactive 29-kDa form may be the basis of hepatic androgen insensitivity during prepuberty and senescence.     

The binding components for 2,3,7,8-tetrachlorodibenzo-p-dioxin and polycyclic aromatic hydrocarbons. Separation from the rat and mouse hepatic cytosol and characterization of a light density component

Using sucrose density gradient centrifugation in a vertical rotor, we have separated three major binding components contained in hepatic cytosols from C57BL/6 mice and Sprague-Dawley rats. Using this preparative method we have obtained, after a 3-h run of 2.4 ml of crude cytosol from 1,4-bis[2-(3,5-dichlorodipyridyloxy)]benzene-treated C57BL/6 mice (approximately 50 mg of protein: 10,000 fmol of Ah receptor) 50 and 75% yields of isolated Ah receptor and carcinogen-binding protein (4 S binding protein), respectively. Both binding components may be kept at -70 degrees C for several months without loss of activity. A third binding component, which did not sediment in a sucrose density gradient (5-20%), even after a 4-h run at 63,000 rpm, was recovered from the top fractions of gradients. When applied to Sephacryl S-300 columns this component was eluted in the void fraction. Resistant to the direct degradative action of nucleases and proteases, this large complex was sequentially converted to its subcomponents by lipoprotein-lipase, proteinase K, and phospholipases. Only the phospholipases are able to abolish the binding capacity of this light density component (LDC) for [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin: hence, we conclude that phospholipids are the true binders of this radioligand. In vitro, this lipoprotein irreversibly binds many hydrophobic radioligands (2,3,7,8-tetrachlorodibenzo-p-dioxin,3-methylcholanthrene, benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, and dexamethasone). Using single vertical spin density gradient ultracentrifugation, the major part (80%) of LDC was characterized as a very low-density lipoprotein, and a minor part (20%) as a low-density lipoprotein. This conclusion was supported by the size of LDC particles (about 25-75 nm) observed in electron microscopy.