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Biomedical subjects

Yeran Bao

Publications and source records attributed to Yeran Bao.

2 recordsLinked to original sources

Will my patient fall?

CONTEXT: Effective multifactorial interventions reduce the frequent falling rate of older patients by 30% to 40%. However, clinical consensus suggests reserving these interventions for high-risk patients. Limiting fall prevention programs to high-risk patients implies that clinicians must recognize features that predict future falls. OBJECTIVE: To identify the prognostic value of risk factors for future falls among older patients. DATA SOURCES AND STUDY SELECTION: Search of MEDLINE (1966-September 2004), CINAHL (1982-September 2004), and authors' own files to identify prospective cohort studies of risk factors for falls that performed a multivariate analysis of such factors. DATA EXTRACTION: Two reviewers independently determined inclusion of articles and assessed study quality. Disagreements were resolved by consensus. Included studies were those identifying the prognostic value of risk factors for future falls among community-dwelling persons 65 years and older. Clinically identifiable risk factors were identified across 6 domains: orthostatic hypotension, visual impairment, impairment of gait or balance, medication use, limitations in basic or instrumental activities of daily living, and cognitive impairment. DATA SYNTHESIS: Eighteen studies met inclusion criteria and provided a multivariate analysis including at least 1 of the risk factor domains. The estimated pretest probability of falling at least once in any given year for individuals 65 years and older was 27% (95% confidence interval, 19%-36%). Patients who have fallen in the past year are more likely to fall again [likelihood ratio range, 2.3-2.8]. The most consistent predictors of future falls are clinically detected abnormalities of gait or balance (likelihood ratio range, 1.7-2.4). Visual impairment, medication variables, decreased activities of daily living, and impaired cognition did not consistently predict falls across studies. Orthostatic hypotension did not predict falls after controlling for other factors. CONCLUSIONS: Screening for risk of falling during the clinical examination begins with determining if the patient has fallen in the past year. For patients who have not previously fallen, screening consists of an assessment of gait and balance. Patients who have fallen or who have a gait or balance problem are at higher risk of future falls.

Accidental Falls↗

Initial transcribed sequence mutations specifically affect promoter escape properties.

Promoter escape efficiency of E. coli RNA polymerase is guided by both the core promoter and the initial transcribed sequence (ITS). Here, we quantitatively examined the escape properties of 43 random initial sequence variants of the phage T5 N25 promoter. The position for promoter escape on all N25-ITS variants occurred at the +15/+16 juncture, unlike the +11/+12 juncture for the wild type N25. These variants further exhibited a 25-fold difference in escape efficiency. ITS changes favoring promoter escape showed a compositional bias that is unrelated to nucleotide substrate binding affinity for the initial positions. Comparing all variants, the natural N25 promoter emerges as having evolved an ITS optimal for promoter escape, giving a high level of productive synthesis after undergoing the shortest abortive program. We supplemented GreB to transcription reactions to better understand abortive initiation and promoter escape in vivo. GreB supplementation elevated productive RNA synthesis 2-5-fold by altering the abortive RNA pattern, decreasing the abundance of the medium (6-10 nt) to long (11-15 nt) abortive RNAs without changing the levels of short (2-5 nt) and very long abortive RNAs (16-20 nt). The GreB-refractive nature of short abortive RNA production may reflect a minimum length requirement of 4-5 bp of the RNA-DNA hybrid for maintaining the stability of initial or backtracked complexes. That the very long abortive RNAs are unaffected by GreB suggests that they are unlikely to be products of polymerase backtracking. How the ITS might influence the course of early transcription is discussed within the structural context of an initial transcribing complex.

Base Sequence↗