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Open Access Publications from the University of California

Scholarly Works (8 results)

  • Article
  • Peer Reviewed
UCLA Previously Published Works (2022)
Two leading impediments to chronic wound healing are polymicrobial infection and biofilm formation. Recent studies have characterized the bacterial fraction of these microbiomes and have begun to elucidate compositional correlations to healing outcomes. However, the factors that drive compositional shifts are still being uncovered. The virome may play an important role in shaping bacterial community structure and function. Previous work on the skin virome determined that it was dominated by bacteriophages, viruses that infect bacteria. To characterize the virome, we enrolled 20 chronic wound patients presenting at an outpatient wound care clinic in a microbiome survey, collecting swab samples from healthy skin and chronic wounds (diabetic, venous, arterial, or pressure) before and after a single, sharp debridement procedure. We investigated the virome using a virus-like particle enrichment procedure, shotgun metagenomic sequencing, and a k-mer-based, reference-dependent taxonomic classification method. Taxonomic composition, diversity, and associations with covariates are presented. We find that the wound virome is highly diverse, with many phages targeting known pathogens, and may influence bacterial community composition and functionality in ways that impact healing outcomes. IMPORTANCE Chronic wounds are an increasing medical burden. These wounds are known to be rich in microbial content, including both bacteria and bacterial viruses (phages). The viruses may play an important role in shaping bacterial community structure and function. We analyzed the virome and bacterial composition of 20 patients with chronic wounds. The viruses found in wounds are highly diverse compared to normal skin, unlike the bacterial composition, where diversity is decreased. These data represent an initial look at this relatively understudied component of the chronic wound microbiome and may help inform future phage-based interventions.
    Cover page: The Chronic Wound Phageome: Phage Diversity and Associations with Wounds and Healing Outcomes.
    • Article
    Research Reports (2001)
    The quality of the construction process is a major factor in determining how well a pavement will perform under traffic loading and when subjected to environmental influences. To improve the construction process, quality control/quality assurance (QC/QA) procedures and pay incentives have been instituted in recent years. It is the objective of this report to demonstrate a rational and feasible method for quantitatively establishing penalties/bonuses for asphalt concrete construction with the initial emphasis placed on new asphalt concrete pavement construction.
      Cover page: Pay Factors for Asphalt-Concrete Construction: Effect of Construction Quality on Agency Costs
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2019)

      Background

      Characterization of the skin and wound microbiome is of high biomedical interest, but is hampered by the low biomass of typical samples. While sample preparation from other microbiomes (e.g., gut) has been the subject of extensive optimization, procedures for skin and wound microbiomes have received relatively little attention. Here we describe an improved method for obtaining both phage and microbial DNA from a single skin or wound swab, characterize the yield of DNA in model samples, and demonstrate the utility of this approach with samples collected from a wound clinic.

      Results

      We find a substantial improvement when processing wound samples in particular; while only one-quarter of wound samples processed by a traditional method yielded sufficient DNA for downstream analysis, all samples processed using the improved method yielded sufficient DNA. Moreover, for both skin and wound samples, community analysis and viral reads obtained through deep sequencing of clinical swab samples showed significant improvement with the use of the improved method.

      Conclusion

      Use of this method may increase the efficiency and data quality of microbiome studies from low-biomass samples.
        Cover page: Improved single-swab sample preparation for recovering bacterial and phage DNA from human skin and wound microbiomes
        • Article
        Research Reports (1997)
        Contractor pay incentives serve two important objectives: 1) they encourage the paving contractor to construct pavements having decidedly superior performance in comparison to those simply meeting minimum specification requirements while, at the same time, maintaining costs at reasonable levels and 2) they provide a rational alternative for dealing with marginally inadequate/adequate construction. Many factors must be considered in the establishment of pay schedules that not only realize these objectives but are also agreeable to both contractor and highway agency alike. The approach taken herein focuses principally on economic impacts to the highway agency. It assumes that an appropriate penalty for inferior construction should be the added cost to the highway agency. It also assumes that the bonus for superior construction should be no greater than the added savings to the highway agency. Smaller maximum bonuses are likely to be necessary to insure budgetary integrity and, coupled with the penalties, may provide sufficient incentive to the contractor for improving construction quality. For new construction, these agency costs/savings are associated primarily with subsequent pavement rehabilitation. Inferior construction hastens future rehabilitation and may increase the cost of rehabilitation as well. As a result, inferior construction increases the present worth of future rehabilitation costs. Superior construction, on the other hand, reduces the present worth of these costs largely by deferring the future rehabilitation. The difference in present worths of rehabilitation costs, as constructed versus as specified and as expected, provides a rational basis for setting the level of penalty/bonus for inferior/superior construction quality.
          Cover page: Pay Factors for Asphalt-Concrete Construction: Effect of Construction Quality on Agency Costs
          • Article
          Research Reports (1995)
          In California, fatigue cracking is considered to be the most important type of distress affecting the performance of asphalt concrete pavements on major state highways. This report describes the results of a laboratory study of the fatigue response of a typical California asphalt concrete mix to define the effects of degree of compaction (as measured by air-void content), asphalt content, and aging on this performance parameter. The test results are then used in analytical simulations to estimate the effects of asphalt and air-void contents (with and without long-term-aging) on pavement performance. These simulations demonstrate that accurate construction control of air void content is more important than accurate control of asphalt content relative to the design target values. For example, a mixture targeted at 5-percent asphalt and 5-percent air voids will suffer a 30-percent reduction in fatigue life if the air-void content exceeds its target by 1-percent but only a 12- percent reduction if the asphalt content is shy of its target by 1 percent. Complicating this matter, however, is the likelihood that smaller-thanspecified asphalt contents will result in increased air-void contents. A mix design and analysis system for fatigue is presented; this system was initially developed as a part of the Strategic Highway Research Program (SHRP) Project A-003A. Its most attractive features include the ability to consider not only laboratory fatigue test results but also the anticipated environment and the ability to make risk assessments about design choices. Refinements to the original SHRP developed methodology are described, including improved procedures for computing pavement temperature profiles as well as calibrations which reflect uniquely California conditions. Analyses of "rich-bottom" pavements (pavements with larger asphalt content in the bottom lift) suggest added potential for improved pavement performance. Finally, a series of recommendations are presented for enhancing the fatigue performance of California pavements which include changes to current construction specifications and/or construction quality assurance procedures.
            Cover page: Fatigue Performance of Asphalt Concrete Mixes and Its Relationship to Asphalt Concrete Pavement Performance in California
            • Article
            Research Reports (1997)
            This report is the second in a series which describe the results of tests on full-scale pavements constructed at the Richmond Field Station (RFS) which have been designed and constructed according to Caltrans procedures. It contains a summary of the results and their interpretation of the Heavy Vehicle Simulator (HVS) tests on the first of four pavement test sections, an asphalt-concrete section containing an asphalt-treated permeable base (ATPB), designated section 500RF. The tests on the four test sections have been performed as part of Goal 1 of the CAL/APT Strategic Plan (1). One objective of the test program [described in Reference (2)] is to develop data to quantitatively verify existing Caltrans pavement design methodologies for Asphalt Treated Permeable Base (ATPB) pavements and conventional Aggregate Base (AB) pavements with regard to failure under trafficking at moderate temperatures (Goal 1), while preparing a uniform platform on which overlays (Goal 3 of the Strategic Plan) will be constructed which also will be trafficked. The objective of the program includes: quantification of the effective elastic moduli of the various pavement layers, based on an ad-hoc use of layered elastic analysis; quantification of the stress dependence of the pavement layers; determination of the failure mechanisms of the various layers; and determination and comparison of the fatigue lives of the two types of pavement structure.
              Cover page: CAL/APT Program: Test Results from Accelerated Pavement Test on Pavement Structure Containing Asphalt Treated Permeable Base (ATPB) Section 500RF
              • Article
              • Peer Reviewed
              Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health, Volume 9, Issue 4 (2008)

              Objectives: Airway management is a critical procedure performed frequently in emergency departments (EDs). Previous studies have evaluated the complications associated with this procedure but have focused only on the immediate complications. The purpose of this study is to determine the incidence and nature of delayed complications of tracheal intubation performed in the ED at an academic center where intubations are performed by emergency physicians (EPs).

              Methods: All tracheal intubations performed in the ED over a one-year period were identified; 540 tracheal intubations were performed during the study period. Of these, 523 charts (96.9%) were available for review and were retrospectively examined. Using a structured datasheet, delayed complications occurring within seven days of intubation were abstracted from the medical record. Charts were scrutinized for the following complications: acute myocardial infarction (MI), stroke, airway trauma from the intubation, and new respiratory infections. An additional 30 consecutive intubations were examined for the same complications in a prospective arm over a 29-day period.

              Results: The overall success rate for tracheal intubation in the entire study group was 99.3% (549/553). Three patients who could not be orally intubated underwent emergent cricothyrotomy. Thus, the airway was successfully secured in 99.8% (552/553) of the patients requiring intubation. One patient, a seven-month-old infant, had unanticipated subglottic stenosis and could not be intubated by the emergency medicine attending or the anesthesiology attending. The patient was mask ventilated and was transported to the operating room for an emergent tracheotomy. Thirty-four patients (6.2% [95% CI 4.3 – 8.5%]) developed a new respiratory infection within seven days of intubation. Only 18 patients (3.3% [95% CI 1.9 – 5.1%]) had evidence of a new respiratory infection within 48 hours, indicating possible aspiration pneumonia secondary to airway management. Three patients (0.5% [95% CI 0.1 – 1.6%]) suffered an acute MI, but none appeared to be related to the intubation. One patient was having an acute MI at the time of intubation and the other two patients had MIs more than 24 hours after the intubation. No patient suffered a stroke (0% [95% CI 0 – 0.6%]). No patients suffered any serious airway trauma such as a laryngeal or vocal cord injury.

              Conclusions: Emergency tracheal intubation in the ED is associated with an extremely high success rate and a very low rate of delayed complications. Complication rates identified in this study compare favorably to reports of emergency intubations in other hospital settings. Tracheal intubation can safely be performed by trained EPs.

              [WestJEM. 2008;9:190-194.]

                Cover page: Delayed Complications of Emergency Airway Management: A Study of 533 Emergency Department Intubations
                • Article
                • Peer Reviewed
                UCLA Previously Published Works (2020)
                Chronic wounds represent a large and growing disease burden. Infection and biofilm formation are two of the leading impediments of wound healing, suggesting an important role for the microbiome of these wounds. Debridement is a common and effective treatment for chronic wounds. We analyzed the bacterial content of the wound surface from 20 outpatients with chronic wounds before and immediately after debridement, as well as healthy skin. Given the large variation observed among different wounds, we introduce a Bayesian statistical method that models patient-to-patient variability and identify several genera that were significantly enriched in wounds vs. healthy skin. We found no difference between the microbiome of the original wound surface and that exposed by a single episode of sharp debridement, suggesting that this debridement did not directly alter the wound microbiome. However, we found that aerobes and especially facultative anaerobes were significantly associated with wounds that did not heal within 6 months. The facultative anaerobic genus Enterobacter was significantly associated with lack of healing. The results suggest that an abundance of facultative anaerobes is a negative prognostic factor in the chronic wound microbiome, possibly due to the increased robustness of such communities to different metabolic environments.
                  Cover page: Microbial predictors of healing and short-term effect of debridement on the microbiome of chronic wounds
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