Lindsay Davis

Bio: Lindsay Davis is an academic researcher from University of Michigan. The author has contributed to research in topics: Campylobacter jejuni & Suicidal ideation. The author has an hindex of 7, co-authored 9 publications receiving 1404 citations.

Campylobacter jejuni : molecular biology and pathogenesis

Abstract: Campylobacter jejuni is a foodborne bacterial pathogen that is common in the developed world. However, we know less about its biology and pathogenicity than we do about other less prevalent pathogens. Interest in C. jejuni has increased in recent years as a result of the growing appreciation of its importance as a pathogen and the availability of new model systems and genetic and genomic technologies. C. jejuni establishes persistent, benign infections in chickens and is rapidly cleared by many strains of laboratory mouse, but causes significant inflammation and enteritis in humans. Comparing the different host responses to C. jejuni colonization should increase our understanding of this organism.

Depression, Stigma, and Suicidal Ideation in Medical Students

Abstract: Context There is a concerning prevalence of depression and suicidal ideation among medical students, a group that may experience poor mental health care due to stigmatization. Objective To characterize the perceptions of depressed and nondepressed medical students regarding stigma associated with depression. Design, Setting, and Participants Cross-sectional Web-based survey conducted in September-November 2009 among all students enrolled at the University of Michigan Medical School (N = 769). Main Outcome Measures Prevalence of self-reported moderate to severe depression and suicidal ideation and the association of stigma perceptions with clinical and demographic variables. Results Survey response rate was 65.7% (505 of 769). Prevalence of moderate to severe depression was 14.3% (95% confidence interval [CI], 11.3%-17.3%). Women were more likely than men to have moderate to severe depression (18.0% vs 9.0%; 95% CI for difference, −14.8% to −3.1%; P = .001). Third- and fourth-year students were more likely than first- and second-year students to report suicidal ideation (7.9% vs 1.4%; 95% CI for difference, 2.7%-10.3%; P = .001). Students with moderate to severe depression, compared with no to minimal depression, more frequently agreed that “if I were depressed, fellow medical students would respect my opinions less” (56.0% vs 23.7%; 95% CI for difference, 17.3%-47.3%; P Conclusions Depressed medical students more frequently endorsed several depression stigma attitudes than nondepressed students. Stigma perceptions also differed by sex and class year.

A Campylobacter jejuni znuA orthologue is essential for growth in low-zinc environments and chick colonization.

Abstract: Campylobacter jejuni infection is a leading cause of bacterial gastroenteritis in the United States and is acquired primarily through the ingestion of contaminated poultry products. Here, we describe the C. jejuni orthologue of ZnuA in other gram-negative bacteria. ZnuA (Cj0143c) is the periplasmic component of a putative zinc ABC transport system and is encoded on a zinc-dependent operon with Cj0142c and Cj0141c, which encode the other two likely components of the transport system of C. jejuni. Transcription of these genes is zinc dependent. A mutant lacking Cj0143c is growth deficient in zinc-limiting media, as well as in the chick gastrointestinal tract. The protein is glycosylated at asparagine 28, but this modification is dispensable for zinc-limited growth and chick colonization. Affinity-purified FLAG-tagged Cj0143c binds zinc in vitro. Based on our findings and on its homology to E. coli ZnuA, we conclude that Cj0143c encodes the C. jejuni orthologue of ZnuA.

The CprS sensor kinase of the zoonotic pathogen Campylobacter jejuni influences biofilm formation and is required for optimal chick colonization.

Abstract: Campylobacter jejuni, a prevalent cause of bacterial gastroenteritis, must adapt to different environments to be a successful pathogen. We previously identified a C. jejuni two-component regulatory system (Cj1226/7c) as upregulated during cell infections. Analyses described herein led us to designate the system CprRS (Campylobacter planktonic growth regulation). While the response regulator was essential, a cprS sensor kinase mutant was viable. The Delta cprS mutant displayed an apparent growth defect and formed dramatically enhanced and accelerated biofilms independent of upregulation of previously characterized surface polysaccharides. Delta cprS also displayed a striking dose-dependent defect for colonization of chicks and was modestly enhanced for intracellular survival in INT407 cells. Proteomics analyses identified changes consistent with modulation of essential metabolic genes, upregulation of stress tolerance proteins, and increased expression of MOMP and FlaA. Consistent with expression profiling, we observed enhanced motility and secretion in Delta cprS, and decreased osmotolerance and oxidative stress tolerance. We also found that C. jejuni biofilms contain a DNase I-sensitive component and that biofilm formation is influenced by deoxycholate and the metabolic substrate fumarate. These results suggest that CprRS influences expression of factors important for biofilm formation, colonization and stress tolerance, and also add to our understanding of C. jejuni biofilm physiology.

Growth and Laboratory Maintenance of Campylobacter jejuni

Abstract: Campylobacter jejuni is a fastidious organism, growing in microaerophilic conditions with a temperature range between 37 degrees and 42 degrees C. Multiple types of media can be used to cultivate it; however, Mueller Hinton broth and agar support the best C. jejuni growth. Optimum atmosphere for C. jejuni is 85% N2, 10% CO2, and 5% O2.

Prevalence of Depression, Depressive Symptoms, and Suicidal Ideation Among Medical Students: A Systematic Review and Meta-Analysis.

Abstract: Importance Medical students are at high risk for depression and suicidal ideation. However, the prevalence estimates of these disorders vary between studies. Objective To estimate the prevalence of depression, depressive symptoms, and suicidal ideation in medical students. Data Sources and Study Selection Systematic search of EMBASE, ERIC, MEDLINE, psycARTICLES, and psycINFO without language restriction for studies on the prevalence of depression, depressive symptoms, or suicidal ideation in medical students published before September 17, 2016. Studies that were published in the peer-reviewed literature and used validated assessment methods were included. Data Extraction and Synthesis Information on study characteristics; prevalence of depression or depressive symptoms and suicidal ideation; and whether students who screened positive for depression sought treatment was extracted independently by 3 investigators. Estimates were pooled using random-effects meta-analysis. Differences by study-level characteristics were estimated using stratified meta-analysis and meta-regression. Main Outcomes and Measures Point or period prevalence of depression, depressive symptoms, or suicidal ideation as assessed by validated questionnaire or structured interview. Results Depression or depressive symptom prevalence data were extracted from 167 cross-sectional studies (n = 116 628) and 16 longitudinal studies (n = 5728) from 43 countries. All but 1 study used self-report instruments. The overall pooled crude prevalence of depression or depressive symptoms was 27.2% (37 933/122 356 individuals; 95% CI, 24.7% to 29.9%, I2 = 98.9%). Summary prevalence estimates ranged across assessment modalities from 9.3% to 55.9%. Depressive symptom prevalence remained relatively constant over the period studied (baseline survey year range of 1982-2015; slope, 0.2% increase per year [95% CI, −0.2% to 0.7%]). In the 9 longitudinal studies that assessed depressive symptoms before and during medical school (n = 2432), the median absolute increase in symptoms was 13.5% (range, 0.6% to 35.3%). Prevalence estimates did not significantly differ between studies of only preclinical students and studies of only clinical students (23.7% [95% CI, 19.5% to 28.5%] vs 22.4% [95% CI, 17.6% to 28.2%]; P = .72). The percentage of medical students screening positive for depression who sought psychiatric treatment was 15.7% (110/954 individuals; 95% CI, 10.2% to 23.4%, I2 = 70.1%). Suicidal ideation prevalence data were extracted from 24 cross-sectional studies (n = 21 002) from 15 countries. All but 1 study used self-report instruments. The overall pooled crude prevalence of suicidal ideation was 11.1% (2043/21 002 individuals; 95% CI, 9.0% to 13.7%, I2 = 95.8%). Summary prevalence estimates ranged across assessment modalities from 7.4% to 24.2%. Conclusions and Relevance In this systematic review, the summary estimate of the prevalence of depression or depressive symptoms among medical students was 27.2% and that of suicidal ideation was 11.1%. Further research is needed to identify strategies for preventing and treating these disorders in this population.

Nutritional immunity: transition metals at the pathogen-host interface.

Abstract: Transition metals occupy an essential niche in biological systems. Their electrostatic properties stabilize substrates or reaction intermediates in the active sites of enzymes, and their heightened reactivity is harnessed for catalysis. However, this heightened activity also renders transition metals toxic at high concentrations. Bacteria, like all living organisms, must regulate their intracellular levels of these elements to satisfy their physiological needs while avoiding harm. It is therefore not surprising that the host capitalizes on both the essentiality and toxicity of transition metals to defend against bacterial invaders. This Review discusses established and emerging paradigms in nutrient metal homeostasis at the pathogen-host interface.

A narrative review on burnout experienced by medical students and residents

Abstract: Objective To summarise articles reporting on burnout among medical students and residents (trainees) in a narrative review. Methods MEDLINE was searched for peer-reviewed, English language articles published between 1990 and 2015 reporting on burnout among trainees. The search used combinations of Medical Subject Heading terms medical student, resident, internship and residency, and burnout, professional. Reference lists of articles were reviewed to identify additional studies. A subset of high-quality studies was selected. Results Studies suggest a high prevalence of burnout among trainees, with levels higher than in the general population. Burnout can undermine trainees’ professional development, place patients at risk, and contribute to a variety of personal consequences, including suicidal ideation. Factors within the learning and work environment, rather than individual attributes, are the major drivers of burnout. Limited data are available regarding how to best address trainee burnout, but multi-pronged efforts, with attention to culture, the learning and work environment and individual behaviours, are needed to promote trainees’ wellness and to help those in distress. Conclusion Medical training is a stressful time. Large, prospective studies are needed to identify cause‒effect relationships and the best approaches for improving the trainee experience.

Intestinal microbiome of poultry and its interaction with host and diet.

Abstract: The gastrointestinal (GI) tract of poultry is densely populated with microorganisms which closely and intensively interact with the host and ingested feed. The gut microbiome benefits the host by providing nutrients from otherwise poorly utilized dietary substrates and modulating the development and function of the digestive and immune system. In return, the host provides a permissive habitat and nutrients for bacterial colonization and growth. Gut microbiome can be affected by diet, and different dietary interventions are used by poultry producers to enhance bird growth and reduce risk of enteric infection by pathogens. There also exist extensive interactions among members of the gut microbiome. A comprehensive understanding of these interactions will help develop new dietary or managerial interventions that can enhance bird growth, maximize host feed utilization, and protect birds from enteric diseases caused by pathogenic bacteria.