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H L Ho

Publications and source records attributed to H L Ho.

7 recordsLinked to original sources

Simple system for optical short-pulse generation in both active mode-locking and self-seeding schemes.

A simple system that simultaneously supports active mode-locking and self-seeding schemes for wavelength-tunable optical short-pulse generation is proposed. The system consists of a gain-switched Fabry-Perot laser diode, an erbium-doped fiber amplifier, a tunable optical filter, and two circulators. The mode-locked optical pulses exhibit good stability, a high side-mode suppression ratio of more than 31 dB over a wide wavelength tuning range of 42 nm, and a pulse width of around 35 ps at a repetition frequency of approximately 2.8 GHz.

Journal Article↗

Variability in physician management of employment during pregnancy.

BACKGROUND AND OBJECTIVES: Successful employment outcomes for pregnant women result from a complex interplay between the woman, her employer, her prenatal care provider, laws and other influences. METHODS: A mail survey about management of employment during pregnancy was sent to directors of US residency programs that train prenatal care providers. Each physician was randomly assigned one of 4 vignette patients whose job involved prolonged standing, rotating shifts and lifting 40 lbs. Half the vignette patients had risk factors for preterm birth and half would have financial difficulty if placed on an unpaid antenatal leave. RESULTS: The 301 respondents estimated that they provide a written job restriction for 20% of their employed pregnant patients, although in 6 clinics the job restriction rate was 100%. For vignettes with preterm birth risk factors, 62.5% of physicians would always recommend a job restriction, 35.6% would do so sometimes, and 2.2% would rarely do so. When the vignette did not have risk factors for preterm birth, 21.5% of the physicians would always recommend a job restriction, 51.3% would do so sometimes, 25.9% would do so rarely and 1.3% would never do so. Economic factors were not associated with prescribing job restrictions. One in 5 of the residency programs provides no teaching on occupational health issues in pregnancy, and 65.1% provide 2 hours or less. CONCLUSIONS: Variability in employment recommendations suggests that some women may not obtain the job modifications that they need, whereas others may be restricted unnecessarily. The limited curriculum time devoted to this topic may make it difficult to train physicians about complex employment issues during pregnancy.

Employment↗

The gene expression of the amiloride-sensitive epithelial sodium channel alpha-subunit is regulated by antagonistic effects between glucocorticoid hormone and ras pathways in salivary epithelial cells.

The functional expression of the amiloride-sensitive epithelial sodium channel (ENaC) in select epithelia is critical for maintaining electrolyte and fluid homeostasis. Although ENaC activity is strictly dependent upon its alpha-subunit expression, little is known about the molecular mechanisms by which cells modulate alpha-ENaC gene expression. Previously, we have shown that salivary alpha-ENaC expression is transcriptionally repressed by the activation of Raf/extracellular signal-regulated protein kinase pathway. Here, this work further investigates the molecular mechanism(s) by which alpha-ENaC expression is regulated in salivary epithelial Pa-4 cells. A region located between -1.5 and -1.0 kilobase pairs of the alpha-ENaC 5'-flanking region is demonstrated to be indispensable for the maximal and Ras-repressible reporter expression. Deletional analyses using heterologous promoter constructs reveal that a DNA sequence between -1355 and -1269 base pairs functions as an enhancer conferring the high level of expression on reporter constructs, and this induction effect is inhibited by Ras pathway activation. Mutational analyses indicate that full induction and Ras-mediated repression require a glucocorticoid response element (GRE) located between -1323 and -1309 base pairs. The identified alpha-ENaC GRE encompassing sequence (-1334/-1306) is sufficient to confer glucocorticoid receptor/dexamethasone-dependent and Ras-repressible expression on both heterologous and homologous promoters. This report demon- strates for the first time that the cross-talk between glucocorticoid receptor and Ras/extracellular signal-regulated protein kinase signaling pathways results in an antagonistic effect at the transcriptional level to modulate alpha-ENaC expression through the identified GRE. In summary, this study presents a mechanism by which alpha-ENaC expression is regulated in salivary epithelial cells.

Animals↗