Publications

IMPORTANCE

The identification of a patient with a rare form of severe dysbetalipoproteinemia allowed the study of the consequences of total absence of apolipoprotein E (apoE).

OBJECTIVES

To discover the molecular basis of this rare disorder and to determine the effects of complete absence of apoE on neurocognitive and visual function and on lipoprotein metabolism.

DESIGN, SETTING, AND PARTICIPANTS

Whole-exome sequencing was performed on the patient's DNA. He underwent detailed neurological and visual function testing and lipoprotein analysis. Lipoprotein analysis was also performed in the Cardiovascular Research Institute, University of California, San Francisco, on blood samples from the proband's mother, wife, 2 daughters, and normolipidemic control participants.

MAIN OUTCOME MEASURES

Whole-exome sequencing, lipoprotein analysis, and neurocognitive function.

RESULTS

The patient was homozygous for an ablative APOE frameshift mutation (c.291del, p.E97fs). No other mutations likely to contribute to the phenotype were discovered, with the possible exception of two, in ABCC2 (p.I670T) and LIPC (p.G137R). Despite complete absence of apoE, he had normal vision, exhibited normal cognitive, neurological, and retinal function, had normal findings on brain magnetic resonance imaging, and had normal cerebrospinal fluid levels of β-amyloid and tau proteins. He had no significant symptoms of cardiovascular disease except a suggestion of myocardial ischemia on treadmill testing and mild atherosclerosis noted on carotid ultrasonography. He had exceptionally high cholesterol content (760 mg/dL; to convert to millimoles per liter, multiply by 0.0259) and a high cholesterol to triglycerides ratio (1.52) in very low-density lipoproteins with elevated levels of small-diameter high-density lipoproteins, including high levels of prebeta-1 high-density lipoprotein. Intermediate-density lipoproteins, low-density lipoproteins, and very low-density lipoproteins contained elevated apoA-I and apoA-IV levels. The patient's apoC-III and apoC-IV levels were decreased in very low-density lipoproteins. Electron microscopy revealed large lamellar particles having electron-opaque cores attached to electron-lucent zones in intermediate-density and low-density lipoproteins. Low-density lipoprotein particle diameters were distributed bimodally.

CONCLUSIONS AND RELEVANCE

Despite a profound effect on lipoprotein metabolism, detailed neurocognitive and retinal studies failed to demonstrate any defects. This suggests that functions of apoE in the brain and eye are not essential or that redundant mechanisms exist whereby its role can be fulfilled. Targeted knockdown of apoE in the central nervous system might be a therapeutic modality in neurodegenerative disorders.

OBJECTIVES

Access to specialty care among safety net patients in the United States is inadequate. Discharging appropriate patients to routine primary care follow-up may improve specialty care access. We sought to identify, by consensus, patients who could safely be discharged from a gastroenterology (GI) clinic, and to evaluate the impact of the discharges on GI clinic work flow.

STUDY DESIGN

Pre- and post intervention.

METHODS

We developed and implemented a modified Delphi process. Gastroenterologists and primary care providers (PCPs) rated their comfort (using 5-point Likert scales) with discharging patients immediately post endoscopy for 24 clinical scenarios, assuming formal recommendations were communicated to the PCP. We examined the impact of implementing these criteria on clinic wait times and on the ratio of new to follow-up visits.

RESULTS

All gastroenterologists (100%; 7 of 7) and 71.0% of PCPs (130 of 183) participated. Consensus was achieved for 13 of the 24 clinical scenarios for which discharge criteria were developed. Post intervention, 403 patients were discharged from the GI clinic, compared with 0 patients in the same 4 calendar months pre-intervention. The ratio of new to follow-up appointments increased from 0.9:1 to 1:1 (P = .05). Median wait time for the third next available appointment at GI clinics decreased from 158 days to 74 days (P = .0001).

CONCLUSIONS

Discharging patients from specialty care back to primary care with consensus standards is one method to improve access to specialty care. Understanding the concerns of all stakeholders is necessary to refine and disseminate this process to other specialties and healthcare systems to ensure timely access to specialty services for all patients.

BACKGROUND

Postinfectious glomerulonephritis (PIGN), a form of immune complex GN, is not well-defined in HIV-infected patients. This study characterizes PIGN in this patients' population and determine the impact of histopathological patterns on renal outcome and mortality.

METHODS

HIV-infected patients with PIGN from September 1998 to July 2013 were identified. Archived slides were reviewed by a blinded renal pathologist, classified into acute, persistent and healed PIGN. Groups were compared using Wilcoxon rank-sum and Fisher's exact test. Survival analyses were performed to determine association of histopathological pattern with renal outcome and mortality.

RESULTS

Seventy-two HIV-infected predominantly African American males were identified with PIGN. Median (interquartile range) age and creatinine at the time of renal biopsy was 48 years (41, 53) and 2.5 mg/dl (1.5, 4.9) respectively. Only 2 (3%) had acute PIGN, 42 (58%) had persistent PIGN and 28 (39%) had healed PIGN. Three patients (4%) had IgA-dominant PIGN. Only 46% of the patients had confirmed positive cultures with Staphylococcus the most common infectious agent. During a median follow up of 17 months, the pathological pattern had no impact on renal outcome (P = 0.95). Overall mortality was high occurring in 14 patients (19%); patients with healed PIGN had significantly increased mortality (P = 0.05).

CONCLUSION

In HIV-infected patients, Staphylococcus is the most common cause of PIGN. Renal outcome was not influenced by the histopathological pattern but those with healed PIGN had greater mortality which was potentially due to a confounder not accounted for in the study.

Claudins are a family of transmembrane proteins that are required for tight junction formation. Claudin (CLDN)-18.1, the only known lung-specific tight junction protein, is the most abundant claudin in alveolar epithelial type (AT) 1 cells, and is regulated by lung maturational agonists and inflammatory mediators. To determine the function of CLDN18 in the alveolar epithelium, CLDN18 knockout (KO) mice were generated and studied by histological, biochemical, and physiological approaches, in addition to whole-genome microarray. Alveolar epithelial barrier function was assessed after knockdown of CLDN18 in isolated lung cells. CLDN18 levels were measured by quantitative PCR in lung samples from fetal and postnatal human infants. We found that CLDN18 deficiency impaired alveolar epithelial barrier function in vivo and in vitro, with evidence of increased paracellular permeability and architectural distortion at AT1-AT1 cell junctions. Although CLDN18 KO mice were born without evidence of a lung abnormality, histological and gene expression analysis at Postnatal Day 3 and Week 4 identified impaired alveolarization. CLDN18 KO mice also had evidence of postnatal lung injury, including acquired AT1 cell damage. Human fetal lungs at 23-24 weeks gestational age, the highest-risk period for developing bronchopulmonary dysplasia, a disease of impaired alveolarization, had significantly lower CLDN18 expression relative to postnatal lungs. Thus, CLDN18 deficiency results in epithelial barrier dysfunction, injury, and impaired alveolarization in mice. Low expression of CLDN18 in human fetal lungs supports further investigation into a role for this tight junction protein in bronchopulmonary dysplasia.

RATIONALE

Interferon gamma (IFN-γ) release assays for latent tuberculosis infection result in a larger-than-expected number of conversions and reversions in occupational screening programs, and reproducibility of test results is a concern.

OBJECTIVES

Knowledge of the relative contribution and extent of the individual sources of variability (immunological, preanalytical, or analytical) could help optimize testing protocols.

METHODS

We performed a systematic review of studies published by October 2013 on all potential sources of variability of commercial IFN-γ release assays (QuantiFERON-TB Gold In-Tube and T-SPOT.TB). The included studies assessed test variability under identical conditions and under different conditions (the latter both overall and stratified by individual sources of variability). Linear mixed effects models were used to estimate within-subject SD.

MEASUREMENTS AND MAIN RESULTS

We identified a total of 26 articles, including 7 studies analyzing variability under the same conditions, 10 studies analyzing variability with repeat testing over time under different conditions, and 19 studies reporting individual sources of variability. Most data were on QuantiFERON (only three studies on T-SPOT.TB). A considerable number of conversions and reversions were seen around the manufacturer-recommended cut-point. The estimated range of variability of IFN-γ response in QuantiFERON under identical conditions was ±0.47 IU/ml (coefficient of variation, 13%) and ±0.26 IU/ml (30%) for individuals with an initial IFN-γ response in the borderline range (0.25-0.80 IU/ml). The estimated range of variability in noncontrolled settings was substantially larger (±1.4 IU/ml; 60%). Blood volume inoculated into QuantiFERON tubes and preanalytic delay were identified as key sources of variability.

CONCLUSIONS

This systematic review shows substantial variability with repeat IFN-γ release assays testing even under identical conditions, suggesting that reversions and conversions around the existing cut-point should be interpreted with caution.

The intracellular scaffold protein IQGAP1 supports protein complexes in conjunction with numerous binding partners involved in multiple cellular processes. Here, we determined that IQGAP1 modulates airway smooth muscle contractility. Compared with WT controls, at baseline as well as after immune sensitization and challenge, Iqgap1-/- mice had higher airway responsiveness. Tracheal rings from Iqgap1-/- mice generated greater agonist-induced contractile force, even after removal of the epithelium. RhoA, a regulator of airway smooth muscle contractility, was activated in airway smooth muscle lysates from Iqgap1-/- mice. Likewise, knockdown of IQGAP1 in primary human airway smooth muscle cells increased RhoA activity. Immunoprecipitation studies indicated that IQGAP1 binds to both RhoA and p190A-RhoGAP, a GTPase-activating protein that normally inhibits RhoA activation. Proximity ligation assays in primary airway human smooth muscle cells and mouse tracheal sections revealed colocalization of p190A-RhoGAP and RhoA; however, these proteins did not colocalize in IQGAP1 knockdown cells or in Iqgap1-/- trachea. Compared with healthy controls, human subjects with asthma had decreased IQGAP1 expression in airway biopsies. Together, these data demonstrate that IQGAP1 acts as a scaffold that colocalizes p190A-RhoGAP and RhoA, inactivating RhoA and suppressing airway smooth muscle contraction. Furthermore, our results suggest that IQGAP1 has the potential to modulate airway contraction severity in acute asthma.

OBJECTIVE

Using disease-modifying antirheumatic drugs (DMARDs) improves outcomes in rheumatoid arthritis (RA) and is a nationally endorsed quality measure. We investigated the prevalence and predictors of receiving glucocorticoids alone for the treatment of RA in a nationwide sample of Medicare beneficiaries.

METHODS

Among individuals ages ≥65 years with RA enrolled in the Part D prescription drug benefit in 2009, we compared those with ≥1 DMARD claim to those receiving glucocorticoid monotherapy, defined as no DMARD claim and an annual glucocorticoid supply of ≥180 days or an annual dose of ≥900 mg of prednisone or equivalent. We fit multivariable models to determine the sociodemographic and clinical factors associated with glucocorticoid monotherapy.

RESULTS

Of 8,125 beneficiaries treated for RA, 10.2% (n = 825) received glucocorticoids alone. Beneficiaries with low incomes were more likely to receive glucocorticoids alone (12.3%; 95% confidence interval [95% CI] 10.9-13.8% versus 9.4%; 95% CI 8.6-10.1%), as were those living in certain US regions. More physician office visits and hospitalizations were associated with glucocorticoid monotherapy. Individuals who had no contact with a rheumatologist were significantly more likely to receive glucocorticoids alone (17.5%; 95% CI 16.0-19.0% versus 8.5%; 95% CI 7.4-9.5% for those with no rheumatology visits versus 1-4 visits).

CONCLUSION

Approximately 1 in 10 Medicare beneficiaries treated for RA received glucocorticoids without DMARDs in 2009. Compared to DMARD users, glucocorticoid users were older, had lower incomes, were more likely to live in certain US regions, and were less likely to have seen a rheumatologist, suggesting persistent gaps in quality of care despite expanded drug coverage under Part D.

Exposure to levamisole-adulterated cocaine can induce a distinct clinical syndrome characterized by retiform purpura and/or agranulocytosis accompanied by an unusual constellation of serologic abnormalities including antiphospholipid antibodies, lupus anticoagulants, and very high titers of antineutrophil cytoplasmic antibodies. Two recent case reports suggest that levamisole-adulterated cocaine may also lead to renal disease in the form of pauci-immune glomerulonephritis. To explore this possibility, we reviewed cases of pauci-immune glomerulonephritis between 2010 and 2012 at an inner city safety net hospital where the prevalence of levamisole in the cocaine supply is known to be high. We identified 3 female patients and 1 male patient who had biopsy-proven pauci-immune glomerulonephritis, used cocaine, and had serologic abnormalities characteristic of levamisole-induced autoimmunity. Each also had some other form of clinical disease known to be associated with levamisole, either neutropenia or cutaneous manifestations. One patient had diffuse alveolar hemorrhage. Three of the 4 patients were treated with short courses of prednisone and cyclophosphamide, 2 of whom experienced stable long-term improvement in their renal function despite ongoing cocaine use. The remaining 2 patients developed end-stage renal disease and became dialysis-dependent. This report supports emerging concern of more wide spread organ toxicity associated with the use of levamisole-adulterated cocaine.

BACKGROUND

Abnormal levels of CD8 T-cell activation persist in HIV-1-infected patients on suppressive antiretroviral therapy (ART) and may be deleterious.

METHODS

CD8 T-cell activation (% coexpressing CD38/HLA-DR) was analyzed on blood specimens from 833 HIV-1-infected patients on ART for ≥96 weeks with concurrent plasma HIV RNA (vRNA) ≤200 copies per milliliter. Factors associated with CD8 T-cell activation were assessed using generalized estimating equations to incorporate longitudinal measurements (median 4/participant).

RESULTS

Participants were 84% men, 47% white, 28% black, and 22% Hispanic, with median pre-ART age 38 years and median ART exposure 144 weeks. CD8 T-cell activation was higher at timepoints when vRNA was 51-200 versus ≤50 copies per milliliter [mean CD8 T-cell activation 23.4% vs. 19.7%; adjusted difference: 1.7% (95% confidence interval: 0.1 to 3.4), P = 0.042]. Restricting to vRNA ≤50 copies per milliliter, multivariable models showed the following factors associated with higher CD8 T-cell activation: older age [≥45 vs. ≤30 years: 3.6% (1.4 to 5.7), P = 0.004], hepatitis C virus antibody positivity [3.6% (0.9 to 6.2), P = 0.032], Hispanic vs. white [7.2% (5.3 to 9.0), P < 0.001], lower concurrent CD4 count [≤200 vs. >500 cells/mm: 2.2% (0.7 to 3.7), P < 0.001], lower concurrent CD4/CD8 ratio [-2.6% (-3.7 to -1.5) per 0.5 unit increase, P < 0.001], and higher pre-ART CD8 T-cell activation [2.0% (1.6 to 2.5) per 10% higher, P < 0.001].

CONCLUSIONS

In participants included in our analysis, residual low-level viremia between 51 and 200 copies per milliliter during ART was shown to be associated with greater CD8 T-cell activation than full suppression to <50 copies per milliliter. Older age, hepatitis C virus antibody positivity, race/ethnicity, higher pre-ART CD8 T-cell activation, and lower concurrent CD4/CD8 ratio and CD4 T-cell count also contribute to greater CD8 T-cell activation during suppressive ART.