Template-free 13-protofilament microtubule–MAP assembly visualized at 8 A resolution

Microtubule-associated proteins (MAPs) are essential for regulating and organizing cellular microtubules (MTs). However, our mechanistic understanding of MAP function is limited by a lack of detailed structural information. Using cryo-electron microscopy and single particle algorithms, we solved the 8 Å structure of doublecortin (DCX)-stabilized MTs. Because of DCX’s unusual ability to specifically nucleate and stabilize 13-protofilament MTs, our reconstruction provides unprecedented insight into the structure of MTs with an in vivo architecture, and in the absence of a stabilizing drug. DCX specifically recognizes the corner of four tubulin dimers, a binding mode ideally suited to stabilizing both lateral and longitudinal lattice contacts. A striking consequence of this is that DCX does not bind the MT seam. DCX binding on the MT surface indirectly stabilizes conserved tubulin–tubulin lateral contacts in the MT lumen, operating independently of the nucleotide bound to tubulin. DCX’s exquisite binding selectivity uncovers important insights into regulation of cellular MTs

The Myth of the Drinker's Bonus

Drinkers earn more than non-drinkers, even after controlling for human capital and local labor market conditions. Several mechanisms by which drinking could increase productivity have been proposed but are unconfirmed; the more obvious mechanisms predict the opposite, that drinking can impair productivity. In this paper we reproduce the positive association between drinking and earnings, using data for adults age 27-34 from the National Longitudinal Survey of Youth (1979). Since drinking is endogenous in this relationship, we then estimate a reduced-form equation, with alcohol prices (proxied by a new index of excise taxes) replacing the drinking variables. We find strong evidence that the prevalence of full-time work increases with alcohol prices %u2013 suggesting that a reduction in drinking increases the labor supply. We also demonstrate some evidence of a positive association between alcohol prices and the earnings of full-time workers. We conclude that most likely the positive association between drinking and earnings is the result of the fact that ethanol is a normal commodity, the consumption of which increases with income, rather than an elixer that enhances productivity.

Pulmonary stretch receptor activity during partial liquid ventilation in cats with healthy lungs

Aim: To study whether pulmonary stretch receptor (PSR) activity in mechanically ventilated young cats with healthy lungs during partial liquid ventilation (PLV) is different from that during gas ventilation (GV). Methods: In 10 young cats (4.4 +/- 0.4 months, 2.3 +/- 0.3 kg; mean B SD), PSR instantaneous impulse frequency (PSR f(imp)) was recorded from single fibres in the vagal nerve during GV and PLV with perfluorocarbon (30 ml/kg) at increasing positive inspiratory pressures (PIP; 1.2, 1.8, 2.2 and 2.7 kPa), and at a positive end-expiratory pressure of 0.5 kPa. Results: All PSRs studied during GV maintained their phasic character with increased impulse frequency during inspiration during PLV. Peak PSR fimp was lower at PIP 1.2 kPa (p < 0.05) and at PIP 2.7 kPa (p = 0.10) during PLV than during GV, giving a lower number of PSR impulses at these two settings during PLV (p < 0.05). Conclusion: The phasic character of PSR activity is similar during GV and PLV. PSR activity is not higher during PLV than during GV in cats with healthy lungs, indicating no extensive stretching of the lung during PLV. Copyright (C) 2004 S. Karger AG, Basel

High School Alcohol Use and Young Adult Labor Market Outcomes

We estimate the relationship between 10th grade binge drinking in 1990 and labor market outcomes in 2000 among National Educational Longitudinal Survey respondents. For females, adolescent drinking and adult wages are unrelated, and negative employment effects disappear once academic achievement is held constant. For males, negative employment effects and, more strikingly, positive wage effects persist after controlling for achievement as well as background characteristics, educational attainment, and adult binge drinking and family and job characteristics. Accounting for illegal drug use and other problem behaviors in 10th grade eliminates the unemployment effect, but strengthens the wage effect. As the latter is not explicable by the health, income or social capital justifications that are often used for frequently observed positive correlations between adult alcohol use and earnings, we conjecture that binge drinking conveys unobserved social skills that are rewarded by employers.

Does the Impact of Managed Care on Substance Abuse Treatment Services Vary By Profit Status?

We extend our previous research by determining whether, and how, the impact of managed care on substance abuse treatment (SAT) services differs by facility ownership. We use the 2000 National Survey of Substance Abuse Treatment Services that contains data on service offerings and other characteristics of 10,513 SAT facilities. For each group of for-profit, not-for-profit, and public facilities, we estimate the impact of managed care (MC) on the number and types of SAT services offered (i.e., indicators of the quality of care). We use IVs to account for possible endogeneity between facilities' involvement in MC and service offerings. We find substantial differences in the magnitude and direction of the impact of MC by facility ownership. On average, MC causes for-profits to offer approximately four (out of 26) additional services, causes publics to offer approximately four fewer services, and has no impact on the number of services offered by not-for-profits. Our findings raise concerns that managed care may reduce the quality of care provided by public SAT facilities by limiting the range of services offered. On the other hand, for-profit clinics are found to increase their range of services; the societal impact of this is unclear for several reasons.