Douglas A. Mata

Structure of the hepatitis E virus-like particle suggests mechanisms for virus assembly and receptor binding

Hepatitis E virus (HEV), a small, non-enveloped RNA virus in the family Hepeviridae, is associated with endemic and epidemic acute viral hepatitis in developing countries. Our 3.5-Å structure of a HEV-like particle (VLP) shows that each capsid protein contains 3 linear domains that form distinct structural elements: S, the continuous capsid; P1, 3-fold protrusions; and P2, 2-fold spikes. The S domain adopts a jelly-roll fold commonly observed in small RNA viruses. The P1 and P2 domains both adopt β-barrel folds. Each domain possesses a potential polysaccharide-binding site that may function in cell-receptor binding. Sugar binding to P1 at the capsid protein interface may lead to capsid disassembly and cell entry. Structural modeling indicates that native T = 3 capsid contains flat dimers, with less curvature than those of T = 1 VLP. Our findings significantly advance the understanding of HEV molecular biology and have application to the development of vaccines and antiviral medications.

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

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.

Comparison of microdissection testicular sperm extraction, conventional testicular sperm extraction, and testicular sperm aspiration for nonobstructive azoospermia: a systematic review and meta-analysis

OBJECTIVE To investigate the relative differences in outcomes among microdissection testicular sperm extraction (micro-TESE), conventional testicular sperm extraction (cTESE), and testicular sperm aspiration (TESA) in men with nonobstructive azoospermia. DESIGN Systematic review and meta-analysis. SETTING Outpatient academic and private urology clinics. PATIENTS(S) Men with nonobstructive azoospermia. INTERVENTION(S) Micro-TESE, cTESE, or TESA. MAIN OUTCOME MEASURE(S) Sperm retrieval (SR). RESULT(S) Fifteen studies with a total of 1,890 patients were identified. The weighted average age of the patients was 34.4 years, the follicular stimulating hormone level was 20.5 mIU/mL, the T was 373 ng/dL, and the testicular volume was 13.5 mL. In a direct comparison, performance of micro-TESE was 1.5 times more likely (95% confidence interval 1.4-1.6) to result in successful SR as compared with cTESE. Similarly, in a direct comparison, performance of cTESE was 2.0 times more likely (95% confidence interval 1.8-2.2) to result in successful SR as compared with TESA. Because of inconsistent reporting, evaluation of other procedural characteristics and pregnancy outcomes was not possible. CONCLUSION(S) Sperm retrieval was higher for micro-TESE compared with cTESE and for cTESE compared with TESA. Standardization of reported outcomes as well as combining all available SR data would help to further elucidate the SRs of these procedures.

Biochemical and Structural Evidence in Support of a Coherent Model for the Formation of the Double-Helical Influenza A Virus Ribonucleoprotein

ABSTRACT Influenza A virions contain eight ribonucleoproteins (RNPs), each comprised of a negative-strand viral RNA, the viral polymerase, and multiple nucleoproteins (NPs) that coat the viral RNA. NP oligomerization along the viral RNA is mediated largely by a 28-amino-acid tail loop. Influenza viral RNPs, which serve as the templates for viral RNA synthesis in the nuclei of infected cells, are not linear but rather are organized in hairpin-like double-helical structures. Here we present results that strongly support a coherent model for the assembly of the double-helical influenza virus RNP structure. First, we show that NP self-associates much more weakly in the absence of RNA than in its presence, indicating that oligomerization is very limited in the cytoplasm. We also show that once NP has oligomerized, it can dissociate in the absence of bound RNA, but only at a very slow rate, indicating that the NP scaffold remains intact when viral RNA dissociates from NPs to interact with the polymerase during viral RNA synthesis. In addition, we identify a previously unknown NP-NP interface that is likely responsible for organizing the double-helical viral RNP structure. This identification stemmed from our observation that NP lacking the oligomerization tail loop forms monomers and dimers. We determined the crystal structure of this NP dimer, which reveals this new NP-NP interface. Mutation of residues that disrupt this dimer interface does not affect oligomerization of NPs containing the tail loop but does inactivate the ability of NPs containing the tail loop to support viral RNA synthesis in minigenome assays. IMPORTANCE Influenza A virus, the causative agent of human pandemics and annual epidemics, contains eight RNA gene segments. Each RNA segment assumes the form of a rod-shaped, double-helical ribonucleoprotein (RNP) that contains multiple copies of a viral protein, the nucleoprotein (NP), which coats the RNA segment along its entire length. Previous studies showed that NP molecules can polymerize via a structural element called the tail loop, but the RNP assembly process is poorly understood. Here we show that influenza virus RNPs are likely assembled from NP monomers, which polymerize through the tail loop only in the presence of viral RNA. Using X-ray crystallography, we identified an additional way that NP molecules interact with each other. We hypothesize that this new interaction is responsible for organizing linear, single-stranded influenza virus RNPs into double-helical structures. Our results thus provide a coherent model for the assembly of the double-helical influenza virus RNP structure. Influenza A virus, the causative agent of human pandemics and annual epidemics, contains eight RNA gene segments. Each RNA segment assumes the form of a rod-shaped, double-helical ribonucleoprotein (RNP) that contains multiple copies of a viral protein, the nucleoprotein (NP), which coats the RNA segment along its entire length. Previous studies showed that NP molecules can polymerize via a structural element called the tail loop, but the RNP assembly process is poorly understood. Here we show that influenza virus RNPs are likely assembled from NP monomers, which polymerize through the tail loop only in the presence of viral RNA. Using X-ray crystallography, we identified an additional way that NP molecules interact with each other. We hypothesize that this new interaction is responsible for organizing linear, single-stranded influenza virus RNPs into double-helical structures. Our results thus provide a coherent model for the assembly of the double-helical influenza virus RNP structure.

In Their Own Words: An Analysis of the Experiences of Medical Interns Participating in a Prospective Cohort Study of Depression.

Purpose To compare the subjective experiences of interns with and without symptoms of depression using a mixed-methods approach. Method In 2007–2008, interns from six institutions were screened for depression before and during internship using an online survey that included the Patient Health Questionnaire (PHQ-9). At the end of internship, participants were asked what made the year difficult, easy, and memorable, and how they had changed. Computerized lexical and qualitative thematic analyses were performed to analyze their free-text responses. Results Sixty-three percent (244/388) of invited interns participated in the original cohort study. Of those, 42% (103/244) answered the open-ended questions for this analysis. Thirty-five percent (36/103) screened positive for clinically significant depression (i.e., PHQ-9 score ≥ 10) during their intern year. Respondents with symptoms of depression were more likely to report problems with cynicism, exhaustion, and stress, while those without them were more likely to mention positive patient care and educational experiences. Respondents with symptoms of depression preferentially described experiences that “broke” their confidence, sense of well-being, and belief in the medical profession, while those who did not described profoundly positive, life-changing experiences regarding interactions with patients and supportive colleagues, through which they grew personally and professionally. Conclusions Depression during internship affects not only objective outcomes like medical errors but also how interns value the profession and themselves, with potentially profound consequences for their future career decisions. Residency programs should implement reactive interventions targeting depression and proactive interventions promoting resilience and well-being to address the issues that lead to depression.

Effects of Testosterone Replacement Therapy on Lower Urinary Tract Symptoms: A Systematic Review and Meta-analysis.

CONTEXT There is a potential risk that testosterone replacement therapy (TRT) may exacerbate lower urinary tract symptoms (LUTS) among aging men with late-onset hypogonadism (LOH) because of testosterones growth-promoting effects on the prostate. OBJECTIVE To compare the change in LUTS severity as assessed using the International Prostate Symptom Score (IPSS) between men receiving TRT versus placebo for the treatment of LOH. EVIDENCE ACQUISITION Systematic search of MEDLINE, Embase, ClinicalTrials.gov, and The Cochrane Library for randomized controlled trials of TRT for LOH published between January 1992 and September 2015. Studies were eligible for inclusion if they were a randomized control trial, used TRT, and assessed LUTS outcomes using the IPSS. Estimates were pooled using random effects meta-analysis. Differences by study-level characteristics were estimated using meta-regression. EVIDENCE SYNTHESIS Data were extracted from 14 trials involving 2029 participants. The average age was 64.5 yr and the average follow-up was 34.4 mo. Seven studies used topical, five used injectable, and two used oral testosterone. There was no statistically significant difference in pooled changes in IPSS from baseline to follow up in men treated with TRT compared with those receiving placebo (-0.41 points [95% confidence interval: -0.89 to 0.07; I(2)=0%, p=0.28] vs. 0.12 points [95% confidence interval: -0.32 to 0.55; I(2)=0%, p=0.81], between-group difference p>0.05). No between-group differences were noted in subanalyses that controlled for potential confounders such as type of testosterone, change in testosterone, aging male symptom scale, or prostate-specific antigen levels (p>0.05 for all comparisons). CONCLUSIONS In this meta-analysis of 14 clinical trials of TRT for LOH, the change in IPSS was similar among men receiving TRT versus placebo, suggesting that TRT treatment does not worsen LUTS among men with LOH. PATIENT SUMMARY In this analysis of 14 clinical trials, testosterone replacement therapy did not worsen lower urinary tract symptoms among men being treated for late-onset hypogonadism.

Significance of lymphovascular invasion in organ‐confined, node‐negative urothelial cancer of the bladder: data from the prospective p53‐MVAC trial

To investigate the association between lymphovascular invasion (LVI) and clinical outcome in organ‐confined, node‐negative urothelial cancer of the bladder (UCB) in a post hoc analysis of a prospective clinical trial. To explore the effect of adjuvant chemotherapy with methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) on outcome in the subset of patients whose tumours exhibited LVI.

Work-Family Conflict and the Sex Difference in Depression Among Training Physicians

Importance Depression is common among training physicians and may disproportionately affect women. The identification of modifiable risk factors is key to reducing this disease burden and its negative impact on patient care and physician career attrition. Objective To determine the presence and magnitude of a sex difference in depressive symptoms and work-family conflict among training physicians; and if work-family conflict impacts the sex difference in depressive symptoms among training physicians. Design, Setting, and Participants A prospective longitudinal cohort study of medical internship in the United States during the 2015 to 2016 academic year in which 3121 interns were recruited across all specialties from 44 medical institutions. Main Outcomes and Measures Prior to and during their internship year, participants reported the degree to which work responsibilities interfered with family life using the Work Family Conflict Scale and depressive symptoms using the Patient Health Questionnaire-9 (PHQ-9). Results Mean (SD) participant age was 27.5 (2.7) years, and 1571 participants (49.7%) were women. Both men and women experienced a marked increase in depressive symptoms during their internship year, with the increase being statistically significantly greater for women (men: mean increase in PHQ-9, 2.50; 95% CI, 2.26-2.73 vs women: mean increase, 3.20; 95% CI, 2.97-3.43). When work-family conflict was accounted for, the sex disparity in the increase in depressive symptoms decreased by 36%. Conclusions and Relevance Our study demonstrates that depressive symptoms increase substantially during the internship year for men and women, but that this increase is greater for women. The study also identifies work-family conflict as an important potentially modifiable factor that is associated with elevated depressive symptoms in training physicians. Systemic modifications to alleviate conflict between work and family life may improve physician mental health and reduce the disproportionate depression disease burden for female physicians. Given that depression among physicians is associated with poor patient care and career attrition, efforts to alleviate depression among physicians has the potential to reduce the negative consequences associated with this disease.

Precision Medicine and Men’s Health

Precision medicine can greatly benefit men’s health by helping to prevent, diagnose, and treat prostate cancer, benign prostatic hyperplasia, infertility, hypogonadism, and erectile dysfunction. For example, precision medicine can facilitate the selection of men at high risk for prostate cancer for targeted prostate-specific antigen screening and chemoprevention administration, as well as assist in identifying men who are resistant to medical therapy for prostatic hyperplasia, who may instead require surgery. Precision medicine-trained clinicians can also let couples know whether their specific cause of infertility should be bypassed by sperm extraction and in vitro fertilization to prevent abnormalities in their offspring. Though precision medicine’s role in the management of hypogonadism has yet to be defined, it could be used to identify biomarkers associated with individual patients’ responses to treatment so that appropriate therapy can be prescribed. Last, precision medicine can improve erectile dysfunction treatment by identifying genetic polymorphisms that regulate response to medical therapies and by aiding in the selection of patients for further cardiovascular disease screening.

Using exit competencies to integrate pathology into the undergraduate clinical clerkships.

In a recent article in HUMAN PATHOLOGY, Ford and Pambrun [1] discuss establishing a set of observable, measurable skills that all graduating medical students should master to demonstrate competency in pathology and laboratorymedicine. This is relevant and important because—regardless of medical specialty—all physicians routinely use the input and interpretation of pathology departments. However, in undergraduate medical education, the role of pathologists is often limited to giving preclinical lectures.Mostmedical schools do not require clinical experiences that highlight the important practical contributions of pathology in day-to-day patient care. As a result, students often graduate without the abilities to, for example, interpret the clinical relevance of a surgical pathology diagnosis or to cogently explain the utility of an autopsy to the next of kin. These discrepancies are disconcerting and emphasize the need for minimal exit competencies in pathology requisition and interpretation. To achieve these competencies, Ford and Pambrun suggest a substantive curricular reform to actively integrate pathology into the clinical clerkships. In this editorial, we offer practical suggestions to accomplish these goals. Training in pathology is not typically a feature of the clinical clerkships for several reasons: competition for curricular time, resistance by other clerkship directors, and a pervasive bias that pathology is not integral to clinical education [2]. Most medical schools devote the third and fourth years to clinical training, with at least 1 year of required clerkships almost uniformly devoid of formal pathology experience. Although students theoretically have the option to explore pathology as an elective, in practice, this does not commonly happen. A study of student opinions by Hung et al [3] found that because pathology was not a core rotation, a majority of students had no clinical exposure to it. Pathology electives were perceived as either “undesirable” or “simply unknown” [3]. This is noteworthy because students uniformly praised the pathology faculty from their first 2 years of medical school yet had little or no appreciation for how they contributed to clinical care. Such observations suggest that clinical exposure to pathology should begin at the same time as clinical exposures to other specialties. Unfortunately, because the clinical years comprise a