Induction of L Forms of Haemophilus influenzae in Culture and Their Demonstration in Human Bronchial Secretions

Transitional forms and round bodies of Haemophilus influenzae were identified in sputa from patients with chronic bronchitis who were receiving penicillin therapy for H. influenzae infections. In vitro growth of L forms of this organism was induced by penicillin and glycine and was studied for comparison with development in vivo. Variant forms demonstrated in sputum were similar to variant forms observed in penicillin-induced L colonies. Recurrence of infection after cessation of therapy was related to reversion of persisting L forms to bacillary forms. That these forms were derived from H. influenzae was established by direct staining with fluoresceinlabeled specific antibody. This demonstration that transitional forms and round bodies of H. influenzae occurred in vivo suggests that L forms of bacteria may be significant in chronic or recurrent infections.     

A Data-Driven Design Evaluation Tool for Handheld Device Soft Keyboards

Thumb interaction is a primary technique used to operate small handheld devices such as smartphones. Despite the different techniques involved in operating a handheld device compared to a personal computer, the keyboard layouts for both devices are similar. A handheld device keyboard that considers the physical capabilities of the thumb may improve user experience. We developed and applied a design evaluation tool for different geometries of the QWERTY keyboard using a performance evaluation model. The model utilizes previously collected data on thumb motor performance and posture for different tap locations and thumb movement directions. We calculated a performance index (PI_TOT, 0 is worst and 2 is best) for 663 designs consisting in different combinations of three variables: the keyboard''s radius of curvature (R) (mm), orientation (O) (°), and vertical location on the screen (L). The current standard keyboard performed poorly (PI_TOT = 0.28) compared to other designs considered. Keyboard location (L) contributed to the greatest variability in performance out of the three design variables, suggesting that designers should modify this variable first. Performance was greatest for designs in the middle keyboard location. In addition, having a slightly upward curve (R = −20 mm) and orientated perpendicular to the thumb''s long axis (O = −20°) improved performance to PI_TOT = 1.97. Poorest performances were associated with placement of the keyboard''s spacebar in the bottom right corner of the screen (e.g., the worst was for R = 20 mm, O = 40°, L =  Bottom (PI_TOT = 0.09)). While this evaluation tool can be used in the design process as an ergonomic reference to promote user motor performance, other design variables such as visual access and usability still remain unexplored.     

Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus

Comparative phylogeography offers a unique opportunity to understand the interplay between past environmental events and life‐history traits on diversification of unrelated but co‐distributed species. Here, we examined the effects of the quaternary climate fluctuations and palaeomarine currents and present‐day marine currents on the extant patterns of genetic diversity in the two most conspicuous mangrove species of the Neotropics. The black (Avicennia germinans, Avicenniaceae) and the red (Rhizophora mangle, Rhizophoraceae) mangroves have similar geographic ranges but are very distantly related and show striking differences on their life‐history traits. We sampled 18 Atlantic and 26 Pacific locations for A. germinans (N = 292) and R. mangle (N = 422). We performed coalescence simulations using microsatellite diversity to test for evidence of population change associated with quaternary climate fluctuations. In addition, we examined whether patterns of genetic variation were consistent with the directions of major marine (historical and present day) currents in the region. Our demographic analysis was grounded within a phylogeographic framework provided by the sequence analysis of two chloroplasts and one flanking microsatellite region in a subsample of individuals. The two mangrove species shared similar biogeographic histories including: (1) strong genetic breaks between Atlantic and Pacific ocean basins associated with the final closure of the Central American Isthmus (CAI), (2) evidence for simultaneous population declines between the mid‐Pleistocene and early Holocene, (3) asymmetric historical migration with higher gene flow from the Atlantic to the Pacific oceans following the direction of the palaeomarine current, and (4) contemporary gene flow between West Africa and South America following the major Atlantic Ocean currents. Despite the remarkable differences in life‐history traits of mangrove species, which should have had a strong influence on seed dispersal capability and, thus, population connectivity, we found that vicariant events, climate fluctuations and marine currents have shaped the distribution of genetic diversity in strikingly similar ways.     

Downregulation of SERINC5 expression in buffy coats of HIV-1-infected patients with detectable or undetectable viral load

Molecular Biology Reports - Among the host restriction factors against HIV, SERINC5 has been described in vitro, but the mRNA level of SERINC5 in vivo has been little studied. We compare SERINC5...     

Association of Maternal Short Sleep Duration With Adiposity and Cardiometabolic Status at 3 Years Postpartum

The purpose of this study was to examine the association of short sleep duration among women in the first year postpartum with adiposity and cardiometabolic status at 3 years postpartum. We studied 586 women in Project Viva, a prospective cohort. At 6 months and 1 year postpartum, women reported the number of hours they slept in a 24‐h period, from which we calculated a weighted average of daily sleep. We used multivariable regression analyses to predict the independent effects of short sleep duration (≤5 h/day vs. >5 h/day) on adiposity, glucose metabolism, lipid metabolism, and adipokines at 3 years postpartum. Women's mean (s.d.) hours of daily sleep in the first year postpartum was 6.7 (0.97) h. After adjusting for age, race/ethnicity, education, parity, prepregnancy BMI, and excessive gestational weight gain, we found that postpartum sleep ≤5 h/day was associated with higher postpartum weight retention (β 1.50 kg; 95% confidence interval (CI): 0.02, 2.86), higher subscapular + triceps skinfold thickness (β 3.94 mm; 95% CI: 1.27, 6.60) and higher waist circumference (β 3.10 cm; 95% CI: 1.25, 4.94) at 3 years postpartum. We did not observe associations of short sleep duration with measures of cardiometabolic status at 3 years postpartum. In conclusion, short sleep duration in the first year postpartum is associated with higher adiposity at 3 years postpartum.     

Variability in essential oil composition of Piper dilatatum L.C. Rich

Twelve samples of air-dried aerial parts of Piper dilatatum L. C. Rich yielded essential oils and their volatile constituents were analyzed by GC and GC–MS. Sesquiterpenes, both hydrocarbons and oxygenated, were the most highly represented classes, the former ranging from 31.5% to 87.7% and the latter varying from 1.8% to 49.4%. Using hierarchical cluster analysis, the oils were divided into seven groups, whose main constituents were: (E)-caryophyllene, α-cadinol and germacrene D (group A); spathulenol, bicyclogermacrene and (Z)-β-ocimene, (group B); spathulenol, germacrene D and (E)-nerolidol, (group C); germacrene D, limonene, α-phellandrene and bicyclogermacrene (group D); β-elemene, germacrene D and β-pinene (group E); curzerene, p-cymene and α-eudesmol (group F); and (Z)-α-bisabolene, curzerene and germacrene D (group G). We have seen that Piper oils from the Amazon present as major constituents terpenoids and phenylpropanoids, always with the predominance of one over another. The essential oils of P. dilatatum presented in this paper, containing only mono- and sesquiterpenes as its major components, is further chemotaxonomic evidence of this dichotomy in the Piper genus.     

Teaching Genres: A Bakhtinian Approach

This article accentuates the cultural/historical nature of teaching. Drawing on Bakhtin's theory of speech genres, it approaches classroom discourse as a composite genre that reflects the history of teaching in each locality. The analysis of a lesson observed in a rural school in Mexico shows how genres drawn from a variety of sources convey different sorts of knowledge as they are woven into ongoing classroom conversation.