Transmembrane organization of mouse P-glycoprotein determined by epitope insertion and immunofluorescence

P-glycoprotein (P-gp) is an integral membrane protein that causes multidrug resistance when overexpressed in tumor cells. Efforts to identify the position and polarity of its 12 putative transmembrane (TM) domains have so far failed to yield a consistent topological model. Recently, we have described a method for topology mapping based on the insertion of a small antigenic peptide epitope (YPYDVPDYA) in predicted intra- or extracellular loops of the protein. The tagged proteins are then functionally expressed in Chinese hamster ovary cells, and the polarity of the inserted tag with respect to plasma membrane is deduced by immunofluorescence in intact or permeabilized cells. We previously localized segments between TM1 and TM2, and TM5 and TM6 as extracellular and segments between TM2 and TM3 and downstream of TM6 as intracellular (Kast, C., Canfield, V., Levenson, R., and Gros, P. (1995) Biochemistry 34, 4402-4411). We have now inserted single epitope tags at positions 207, 235, 276, 741, 782, 797, 815, 849, 887, 961, and 1024; double epitope tags at positions 736, 849, and 961; and a triple epitope tag at position 849. Insertions of epitopes at positions 235, 736, 741, 849, 887, 961, and 1024 resulted in functional proteins, whereas insertions at positions 207, 276, 782, 797, and 815 abrogated the capacity of P-gp to confer multidrug resistance. The epitope tags inserted at positions 736, 849, and 961 were localized extracellularly, whereas tags at positions 235, 887, and 1024 mapped intracellularly. These results indicate that the intervening segments separated by TM4-TM5, TM10-TM11, and downstream of TM12 are cytoplasmic; segments delineated by TM7-TM8, TM9-TM10, and TM11-TM12 are extracellular. Our combined analysis of the amino- and carboxyl-terminal halves of P-gp supports a 12-TM domain topology with intracellular amino and carboxyl termini and ATP binding sites and an extracellular glycosylated loop (TM1-TM2) in agreement with hydropathy prediction. These results are clearly distinct from those obtained by the analysis of truncated P-gps in vitro and in heterologous expression systems.     

Behavioral Inhibition and Amplification During Emotional Arousal: A Comparison of Two Age Groups.

This study investigated age differences in the ability to suppress and amplify expressive behavior during emotional arousal. Young and old participants viewed 3 film clips about medical procedures while their behavioral, autonomic, and subjective responses were recorded. Half of the participants viewed all 3 films without additional instructions; the other half was asked to suppress and amplify their behavioral expression during the 2nd and 3rd films. Except for heart rate, suppression and amplification produced similar patterns of autonomic activation. Neither suppression nor amplification had effects on self-reported emotion. There were no age differences in the ability to suppress or amplify emotional expression or in their physiological or subjective consequences. Considering that older people's unregulated reactivity was lower than that of young adults, suppression may have been easier and amplification more difficult for older adults. Voluntary emotion regulation might be one domain of human performance that is spared from age-related losses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A home-based exercise program for nondisabled older adults

OBJECTIVES: This paper describes a videotaped, home-based, strength training program, titled Strong-for-Life and reports on its effectiveness in improving muscle strength, psychological well-being, and health status in a sample of older persons. DESIGN AND SETTING: We enrolled 102 nondisabled, community-dwelling older people aged 66 to 87, identified from the Medicare beneficiary list, into a randomized, controlled trial. MEASUREMENTS: Effectiveness was based on change in isokinetic upper and lower extremity muscle strength, psychologic well-being, and health status. RESULTS: Results revealed several statistically significant short-term benefits after 12 to 15 weeks of exercise, especially for men. Younger older adults demonstrated a 10% improvement in knee extensor strength relative to control subjects. Older male exercisers achieved significant differences relative to controls in perceived anger, tension, and overall social functioning. Male exercisers, in general, achieved significant improvement in perceived vigor. Women did not report psychological benefits following participation in the program. CONCLUSION: Study results reveal that the Strong for Life program, designed to be widely disseminated to the nondisabled older population, has many short-term positive benefits.     

Formation and properties of metallic organotin films

Semiconductive and conductive films of metallic appearance are formed by glow discharge of appropriate organometallic compounds. Tetramethyltin is used as a starting compound for the film-forming experiments. The resulting films contain carbon, tin and hydrogen with a carbon-to-tin atomic ratio of 2.5 or less. These films are semiconductors with conductivities between 2 × 10^-1 and $\text{1 × 10}{}^{-2}\text{Ω}{}^{-1}\text{cm}{}^{-1}$. Transmission electron microscopy shows the films to be amorphous. Films of a certain composition are transformed to β-Sn on exposure to an electron beam. Thermal treatment increases the conductivity gradually to values of about $\text{1 × 10}{}^2\text{Ω}{}^{-1}\text{cm}{}^{-1}$.     

Photonic-crystal surface-emitting laser near 1.55 /spl mu/m on gold-coated silicon wafer

An InP/InGaAs-based photonic band-edge laser bonded on silicon operating near 1.55 mum is presented. A gold reflector positioned below the slab containing the active layer reduces the optical losses of the Bloch-mode resonator. As a result, a quality factor exceeding 8000 is obtained at transparency leading to a laser threshold as low as 3.4 muJ/cm²     

Plotting the Course of Photographic Development

The advantage of plotting density versus time data on log instead of linear axes for studies of the mechanism of development is explained. When the data for low densities are corrected, if necessary, to silver mass and are plntted on log axes, a slope near 3 indicates that the rate of development varies as the effective surface area of the develnp<:d silver, whereas a slope near unity suggests that th e rate of development responds to the mass, or area of the silver halide. Data from the classic experiments of James, and Pontius and Willis are re-evaluated in this way. It is shown that there is no need ro invoke a special mechanism to account for the S-shape of the develnpment curve shown by some agents like hydroquinone. Slopes greater than 3 can be ascribed to a phase of very slow reaction prior to the onset of development with the rate constant that characterizes the phase of measurable density.     

Longitudinal findings from the normative aging study: I. Does mental health change with age?

Longitudinal changes in self-reported symptoms were investigated using the Cornell Medical Index (CMI) in a sample of 2,041 men. The average man completed 5 CMIs (range?=?2–8) over 17 (range?=?2–25) years. Using a two-stage growth model, we first regressed symptoms against time on study for each man. The average slope of physical symptoms showed a moderate increase over time, but the average slope of psychological symptoms showed little change. Next individual differences in change were examined using age at entry as an explanatory variable. Age accounted for 50% of the variance in physical symptoms at entry and 7% of the variance in slopes, but explained neither baseline level nor change in psychological symptoms. Rather, a U-shaped curve described the relation between age and psychological symptom change. These results, in concert with a developmental perspective, may help reconcile conflicting findings on aging and mental health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in values between short-term and long-term therapists.

We empirically examined S. H. Budman and A. S. Gurman's (see record 1984-04498-001) theoretical proposals concerning major differences in the value systems of long- vs. short-term therapists. Ss were 222 randomly selected licensed psychologists who indicated their preferred approach (short-term or long-term). Values were assessed with a scale designed for the study. Overall, results indicate that therapists who prefer a short-term approach are more likely to endorse the proposed values of the short-term therapist than are therapists who prefer a long-term approach. This finding held even after the authors controlled for the significant contributions of theoretical orientation and therapeutic practice variables. Specifically, short-term (vs. long-term) therapists believed more that psychological change could occur outside of therapy and that setting time limits would intensify the therapeutic work. Implications for the practice of brief therapy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brief therapy prevalence and training: A national survey of psychologists.

Psychologists find themselves ill-prepared to meet the increasing demand for briefer and briefer therapies. Members of APA Divisions 12 (Clinical Psychology) and 29 (Psychotherapy) were surveyed (N?=?1,250; return rate?=?57%) regarding their practice of and training in brief therapy. Results indicate that almost all (89%) of the respondents perform some brief therapy and, on average, spend half their time doing it. With regard to training, however, half of those conducting brief therapy have never taken any brief therapy courses. Additional findings indicate theoretical orientation, gender, region, practice site, and setting are significantly related to the amount of brief therapy delivered. Overall, the amount and helpfulness of brief therapy training are significantly related to one's skill, satisfaction, and positive attitude toward brief therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)