Validity and Characterization of Time to Symptom Resolution Outcome Measures in the ACTIV-2/A5401 Outpatient COVID-19 Treatment Trial

BACKGROUND

Time to symptom resolution measures were used in outpatient coronavirus disease 2019 (COVID-19) treatment trials without prior validation.

METHODS

ACTIV-2/A5401 trial participants completed a COVID-19 diary assessing 13 targeted symptoms and global experience (overall COVID-19 symptoms, return to pre-COVID-19 health) daily for 29 days. We evaluated concordance of time to sustained (2 days) resolution of all targeted symptoms (TSR) with resolution of overall symptoms and return to health in participants receiving placebo.

RESULTS

The analysis included 77 high-risk and 81 standard-risk participants with overall median 6 days of symptoms at entry and median age 47 years, 50% female, 82% white, and 31% Hispanic/Latino. Correlation between TSR and resolution of overall symptoms was 0.80 and 0.68, and TSR and return to health, 0.66 and 0.57 for high- and standard-risk groups, respectively. Of the high- and standard-risk participants, 61% and 79%, respectively, achieved targeted symptom resolution, of which 47% and 43%, respectively, reported symptom recurrence. Requiring >2 days to define sustained resolution reduced the frequency of recurrences.

CONCLUSIONS

There was good internal consistency between TSR and COVID-19-specific global outcomes, supporting TSR as a trial end point. Requiring >2 days of symptom resolution better addresses natural symptom fluctuations but must be balanced against the potential influence of non-COVID-19 symptoms.

CLINICAL TRIALS REGISTRATION

NCT04518410.

Long COVID After Bamlanivimab Treatment

BACKGROUND

Prospective evaluations of long COVID in outpatients with coronavirus disease 2019 (COVID-19) are lacking. We aimed to determine the frequency and predictors of long COVID after treatment with the monoclonal antibody bamlanivimab in ACTIV-2/A5401.

METHODS

Data were analyzed from participants who received bamlanivimab 700 mg in ACTIV-2 from October 2020 to February 2021. Long COVID was defined as the presence of self-assessed COVID symptoms at week 24. Self-assessed return to pre-COVID health was also examined. Associations were assessed by regression models.

RESULTS

Among 506 participants, median age was 51 years. Half were female, 5% Black/African American, and 36% Hispanic/Latino. At 24 weeks, 18% reported long COVID and 15% had not returned to pre-COVID health. Smoking (adjusted risk ratio [aRR], 2.41 [95% confidence interval {CI}, 1.34- 4.32]), female sex (aRR, 1.91 [95% CI, 1.28-2.85]), non-Hispanic ethnicity (aRR, 1.92 [95% CI, 1.19-3.13]), and presence of symptoms 22-28 days posttreatment (aRR, 2.70 [95% CI, 1.63-4.46]) were associated with long COVID, but nasal severe acute respiratory syndrome coronavirus 2 RNA was not.

CONCLUSIONS

Long COVID occurred despite early, effective monoclonal antibody therapy and was associated with smoking, female sex, and non-Hispanic ethnicity, but not viral burden. The strong association between symptoms 22-28 days after treatment and long COVID suggests that processes of long COVID start early and may need early intervention.

CLINICAL TRIALS REGISTRATION

NCT04518410.

Recurrence of Symptoms Following a 2-Day Symptom Free Period in Patients With COVID-19

This cohort study of US adults with untreated COVID-19 examines the types and length of symptoms experienced following symptom recurrence.

Methotrexate Inhibits T Cell Proliferation but Not Inflammatory Cytokine Expression to Modulate Immunity in People Living With HIV

Inflammation associated with increased risk of comorbidities persists in people living with HIV (PWH) on combination antiretroviral therapy (ART). A recent placebo-controlled trial of low-dose methotrexate (MTX) in PWH found that numbers of total CD4 and CD8 T cells decreased in the low-dose MTX arm. In this report we analyzed T cell phenotypes and additional plasma inflammatory indices in samples from the trial. We found that cycling (Ki67+) T cells lacking Bcl-2 were reduced by MTX but plasma inflammatory cytokines were largely unaffected. In a series of in vitro experiments to further investigate the mechanisms of MTX activity, we found that MTX did not inhibit effector cytokine production but inhibited T cell proliferation downstream of mTOR activation, mitochondrial function, and cell cycle entry. This inhibitory effect was reversible with folinic acid, suggesting low-dose MTX exerts anti-inflammatory effects in vivo in PWH largely by blocking T cell proliferation via dihydrofolate reductase inhibition, yet daily administration of folic acid did not rescue this effect in trial participants. Our findings identify the main mechanism of action of this widely used anti-inflammatory medicine in PWH and may provide insight into how MTX works in the setting of other inflammatory conditions.

A Randomized, Placebo-Controlled Trial Assessing the Effect of VISBIOME ES Probiotic in People With HIV on Antiretroviral Therapy

BACKGROUND

A5350, a phase II, randomized, double-blind study, evaluated the safety and tolerability of the probiotic Visbiome Extra Strength (ES) over 24 weeks and measured effects on inflammation and intestinal barrier function.

METHODS

The primary outcome was change in soluble CD14 (sCD14) levels; secondary outcomes included safety and tolerability, markers of inflammation and cellular activation, and microbiome. In a substudy, gut permeability was assessed by paired colonic biopsies measuring the area of lamina propria occupied by CD4+ cells, interleukin (IL)-17+ cells, and myeloperoxidase (MPO). Changes between arms were compared with the 2-sample t test with equal variance or the Wilcoxon rank-sum test. For safety, the highest graded adverse events (AEs) were compared between arms using the Fisher exact test.

RESULTS

Overall, 93 participants enrolled: 86% male, median age 51 years, median CD4 count 712 cells/mm3. Visbiome ES was safe and well tolerated. There was no difference in mean change in sCD14 from baseline to week 25/26 between placebo (mean change, 92.3 µg/L; 95% CI, -48.5 to 233 µg/L) and Visbiome ES (mean change, 41.0 µg/L; 95% CI, -94.1 to 176.2 µg/L; P=.60). Similarly, no statistically significant differences between arms in inflammatory marker changes were identified. In substudy participants, no statistical differences between arms for change in cellular marker expression or gut permeability were observed (P>.05 for all). The microbiome demonstrated increased probiotic species and a significant decrease in Gammaproteobacteria (P=.044) in the Visbiome ES arm.

CONCLUSIONS

Visbiome ES was safe and altered the microbiome but demonstrated no effect on systemic inflammatory markers, pathology, or gut permeability in antiretroviral therapy-treated people with HIV.

Safety and Impact of Low-dose Methotrexate on Endothelial Function and Inflammation in Individuals With Treated Human Immunodeficiency Virus: AIDS Clinical Trials Group Study A5314

BACKGROUND

Chronic inflammation in treated HIV infection is associated with mortality and atherosclerotic cardiovascular disease (ASCVD). We evaluated the safety and potential efficacy of low-dose methotrexate (LDMTX) in treated HIV.

METHODS

This was a phase 2 randomized, double-blind, multicenter trial in adults ≥40 years old with treated HIV, with CD4+ T-cell count ≥400 cells/μL and with/at increased risk for ASCVD. Participants received LDMTX (5-15 mg/week) or placebo (plus folic acid) for 24 weeks and were followed for an additional 12 weeks. Primary endpoints were safety and brachial artery flow-mediated dilation (FMD).

RESULTS

The 176 participants (90% male) had a median (Q1, Q3) age of 54 (49, 59) years. LDMTX was associated with decreases in CD4+ T cells at week 24 and CD8+ T cells at weeks 8, 12, and 24. Eleven participants (12.8%) experienced safety events in the LDMTX group vs 5 (5.6%) in placebo (Δ = 7.2%, upper 1-sided 90% CI, 13.4%; Pnoninferiority = .037). Week 24 change in FMD was 0.47% with LDMTX and 0.09% with placebo (P = .55). No inflammatory markers changed differentially with LDMTX compared to placebo.

CONCLUSIONS

Adults with HIV and increased ASCVD risk treated with LDMTX had more safety events than with placebo, but the prespecified noninferiority margin of 15% was not exceeded. LDMTX had no significant effect on endothelial function or inflammatory biomarkers but was associated with a significant decrease in CD8+ T cells. The balance of risks and potential benefits of LDMTX in this population will require additional investigation.

CLINICAL TRIALS REGISTRATION

NCT01949116.

1202 Validation Of A Novel Wearable Home Sleep Testing Device For Assessment Of Obstructive Sleep Apnea

Introduction

There is a substantial need for an accurate and easy-to-use tool for obstructive sleep apnea (OSA) assessment. Belun Ring Platform (BRP), a novel photoplethysmography (PPG)-based home sleep apnea testing system with a proprietary deep learning algorithm, has been shown to have good sensitivity and specificity in predicting OSA in subjects without significant comorbidities and medications known to affect heart rate (HR). In this study, we further tested its performance in subjects referred for in-lab polysomnography (PSG) assessment of sleep disorders without excluding those with non-arrhythmia comorbidities or the subjects on HR-affecting medications.

Methods

PSG was recorded simultaneously with the Ring in the sleep lab and the studies were manually scored by certified sleep technicians according to the AASM Scoring manual version 2.4. Exclusion criteria include age <18, unstable cardiopulmonary status, recent hospitalization within 30 days, significant arrhythmias, baseline HR <50 or >100, home oxygen use, pacemaker/defibrillator, post-cardiac transplantation or Left ventricular assist device.

Results

A cohort of 78 individuals (26 males and 52 females, age 50.5) were studied with 26 taking HR-affecting medications. Of these, 35 (45%) had AHI < 5; 14 (18%) had AHI 5-15; 15 (19%) had AHI 15-30; 14 (18%) had AHI > 30. The Ring-REI correlated well with the PSG-AHI (r =0.83, P <0.001). The accuracy, sensitivity, specificity in categorizing AHI >15 were 0.808, 0.931, and 0.735 respectively. The positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio were 0.675, 0.947, 3.509, and 0.094 respectively. The use of HR-affecting medications did not significantly affect the sensitivity and specificity of BRP in predicting OSA (P =0.16 and 0.44 respectively).

Conclusion

BRP is promising as a reasonable tool for OSA assessment and can potentially be incorporated into a broad spectrum of clinical practices for identification of patients with OSA.

Support

This study is supported by a Grant from Belun Technology Company Limited.

Telmisartan Therapy Does Not Improve Lymph Node or Adipose Tissue Fibrosis More Than Continued Antiretroviral Therapy Alone

Background

Fibrosis in lymph nodes may limit CD4+ T-cell recovery, and lymph node and adipose tissue fibrosis may contribute to inflammation and comorbidities despite antiretroviral therapy (ART). We hypothesized that the angiotensin receptor blocker and peroxisome proliferator-activated receptor γ agonist telmisartan would decrease lymph node or adipose tissue fibrosis in treated human immunodeficiency virus type 1 (HIV) infection.

Methods

In this 48-week, randomized, controlled trial, adults continued HIV-suppressive ART and received telmisartan or no drug. Collagen I, fibronectin, and phosphorylated SMAD3 (pSMAD3) deposition in lymph nodes, as well as collagen I, collagen VI, and fibronectin deposition in adipose tissue, were quantified by immunohistochemical analysis at weeks 0 and 48. Two-sided rank sum and signed rank tests compared changes over 48 weeks.

Results

Forty-four participants enrolled; 35 had paired adipose tissue specimens, and 29 had paired lymph node specimens. The median change overall in the percentage of the area throughout which collagen I was deposited was -2.6 percentage points (P = 0.08) in lymph node specimens and -1.3 percentage points (P = .001) in adipose tissue specimens, with no between-arm differences. In lymph node specimens, pSMAD3 deposition changed by -0.5 percentage points overall (P = .04), with no between-arm differences. Telmisartan attenuated increases in fibronectin deposition (P = .06). In adipose tissue, changes in collagen VI deposition (-1.0 percentage point; P = .001) and fibronectin deposition (-2.4 percentage points; P < .001) were observed, with no between-arm differences.

Conclusions

In adults with treated HIV infection, lymph node and adipose tissue fibrosis decreased with continued ART alone, with no additional fibrosis reduction with telmisartan therapy.

Brachial Artery Echogenicity and Grayscale Texture Changes in HIV-Infected Individuals Receiving Low-Dose Methotrexate

Objective- We evaluated the biological effects of low-dose methotrexate on 3 novel brachial artery grayscale ultrasound measures that may indicate subclinical arterial injury. Approach and Results- Exploratory analysis from a clinical trial of people with HIV infection at increased cardiovascular disease risk who were randomly assigned to low-dose methotrexate (target dose 15 mg/wk) or placebo. Brachial artery ultrasound grayscale median, gray level difference statistic texture-contrast (GLDS-CON), and gray level texture entropy were measured at baseline and after 24 weeks of intervention. Findings from the intention-to-treat (N=148) and adequately-dosed (N=118) populations were consistent, so the adequately-dosed population results are presented. Participants were a median (Q1, Q3) age of 54 (50, 60) years. After 24 weeks, the low-dose methotrexate intervention was associated with a 25.4% (-18.1, 58.6; P=0.007) increase in GLDS-CON compared with 1.3% (-29.1, 44.7; P=0.97) with placebo ( P=0.05) and a 0.10 u (-0.06, 0.23; P=0.026) increase in entropy compared with 0.02 u (-0.11, 0.14; P=0.54) with placebo ( P=0.14). At week 24, changes in CD4+ T cells correlated inversely with changes in GLDS-CON (ρ=-0.20; P=0.031), and entropy (ρ=-0.21; P=0.023). Changes in D-dimer levels, but no other inflammatory biomarkers, also correlated inversely with changes in GLDS-CON (ρ=-0.23; P=0.014) and entropy (ρ=-0.26; P=0.005). Conclusions- Brachial artery GLDS-CON and entropy increased after 24 weeks of low-dose methotrexate, though the latter was not significantly different from placebo. Grayscale changes were associated with decreases in CD4+ T-cell and D-dimer concentrations and may indicate favorable arterial structure changes.

Patient-derived iPSCs show premature neural differentiation and neuron type-specific phenotypes relevant to neurodevelopment

Ras/MAPK pathway signaling is a major participant in neurodevelopment, and evidence suggests that BRAF, a key Ras signal mediator, influences human behavior. We studied the role of the mutation BRAFQ257R, the most common cause of cardiofaciocutaneous syndrome (CFC), in an induced pluripotent stem cell (iPSC)-derived model of human neurodevelopment. In iPSC-derived neuronal cultures from CFC subjects, we observed decreased p-AKT and p-ERK1/2 compared to controls, as well as a depleted neural progenitor pool and rapid neuronal maturation. Pharmacological PI3K/AKT pathway manipulation recapitulated cellular phenotypes in control cells and attenuated them in CFC cells. CFC cultures displayed altered cellular subtype ratios and increased intrinsic excitability. Moreover, in CFC cells, Ras/MAPK pathway activation and morphological abnormalities exhibited cell subtype-specific differences. Our results highlight the importance of exploring specific cellular subtypes and of using iPSC models to reveal relevant human-specific neurodevelopmental events.

Bone mineral density reductions after tenofovir disoproxil fumarate initiation and changes in phosphaturia: a secondary analysis of ACTG A5224s

Background

It is unknown if the greater reductions in bone mineral density (BMD) associated with initiation of tenofovir disoproxil fumarate compared with abacavir in previously untreated HIV-infected participants in the ACTG A5224s clinical trial were associated with potentially worsening tenofovir-related phosphaturia.

Methods

We correlated changes in BMD at the hip and spine with changes in phosphaturia [transtubular reabsorption of phosphorus (TRP) and tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR)] from entry through week 96 in those initiating tenofovir ( n  =   134) versus abacavir ( n  =   135) with efavirenz or atazanavir/ritonavir in A5224s. We also correlated changes in BMD with tenofovir AUC measured between weeks 4 and 24.

Results

Changes in TRP and TmP/GFR through week 96 between the tenofovir and abacavir arms were not significantly different (both P  ≥   0.70) and did not differ with use of efavirenz versus atazanavir/ritonavir. There were no significant correlations between changes in either TRP or TmP/GFR and with either hip or spine BMD in the tenofovir arms. Tenofovir AUC was significantly correlated with changes in hip BMD, but not spine BMD, at week 24 ( r  =   -0.22, P  =   0.028) and week 48 ( r  =   -0.26, P  =   0.010), but not at week 96 ( r  =   -0.14, P  =   0.18).

Conclusions

Changes in phosphaturia were not different between the tenofovir and abacavir arms in A5224s. Changes in hip and spine BMD with tenofovir were not related to changes in phosphaturia. However, tenofovir exposure was weakly associated with changes in hip BMD through week 48.

Acute and Chronic Therapies in Pediatric Inflammatory Central Nervous System Diseases

Recognition of pediatric neuroinflammatory disorders has increased in recent years, together with an increased knowledge of the immune mechanisms underlying these disorders. These insights have led to paying greater attention to the classification of these disorders, and importantly, increasing information on therapeutic interventions that may improve outcomes. Furthermore, this has occurred in the wake of the development of multiple targeted immune therapies, thus creating a complex treatment landscape. This review aims to summarize the available literature regarding acute and chronic therapies for pediatric inflammatory central nervous system (CNS) disorders. A standardized approach to the initial management of these diseases is presented.

Abstract OT1-01-07: A phase 2 study of eribulin followed by doxorubicin and cyclophosphamide as preoperative therapy for HER2-negative inflammatory breast cancer

Background: HER2 negative(neg) inflammatory breast cancer(IBC) exhibits relative resistance to chemotherapy evidenced by pCR(pathologic complete response rate) rates of 12-25% with preoperative taxane/anthracycline regimens. Eribulin(Eisai®) inhibits microtubular function via sequestration of tubulin into nonfunctional aggregates, thus being effective against taxane-resistant cancer. Preclinical data shows 2 mechanisms of action: reversion of EMT(epithelial to mesenchymal transition) and normalization of tumor vascularity. Treatment of triple negative breast cancer(TNBC) cell-lines with eribulin results in downregulation of mesenchymal markers with concomitant increase in expression of classical epithelial markers(Yoshida BJC 2014). In PDX models, eribulin improved blood perfusion in central region of tumors, increased vessel density, reduced vessel diameter, and reduced hypoxia. IBC is highly angiogenic, with increased microvessel density, higher fraction of proliferating endothelial cells and greater expression of pro-angiogenic genes compared with non-IBC(McCarthy CCR 2002). This preoperative study(EAC) exploits the angiogenic properties of IBC with the treatment scheme of eribulin(E) followed by doxorubicin/cyclosphosphamide(AC) in newly diagnosed HER2neg IBC.

Methods: Pts with HER2neg Stage III (cT4d,any N,M0) IBC are eligible if they have not received prior therapy for BC, have adequate organ function, cardiac ejection fraction &gt; 50%, and willing to undergo 2 research biopsies (rbx) of the affected breast. Following baseline rbx, pts receive cycle 1, day(d)1 eribulin 1.4 mg/m2. A 2nd rbx occurs on d8, prior to dosing of E. Following 3 more cycles of E(1.4mg/m2 d1,d8,every 21d), pts receive 4 cycles of dose-dense AC(A-60 mg/m2,C-600mg/m2 every 14d). Pts with adequate disease response undergo mastectomy/axillary lymph node dissection followed by chest wall/regional lymph node radiation. Adjuvant endocrine therapy is used if hormone receptor positive. An imaging sub-study evaluates tumor perfusion via DCE-MRI pre and post 1st dose E.

Correlatives: To investigate whether E induces reversion of EMT in IBC, expression of 10 EMT-related genes are determined in each rbx, and normalization of tumor vessel phenotype are assessed by expression of 15 angiogenesis-related genes in rbx by RT-qPCR. Gene expression will be repeated on residual tumor at mastectomy. An imaging sub-study of DCE-MRI (10 pts) will assess vascular remodeling via changes in Ktrans , ve and vp determination of IBC region of interest, core and rim and changes in the iAUC computed pre and post 1st dose E.

Statistics: The primary endpoint is pCR. A Simon two-stage design is used. If the proportion of pts having pCR is &lt; 0.10 then EAC is considered minimally effective, versus alternative hypothesis that EAC is worthy of further study if proportion pCR &gt; 0.30. In the 1st stage, if &lt; 2/16 pts have pCR, the study is stopped; if &gt; 3 pts have pCR, the study proceeds. In the 2nd stage, EAC is rejected if &lt; 4 of 25 pts have a pCR(α=0.10;β=0.10). Up to 25 pts will be enrolled. Secondary endpoints are residual cancer burden, disease-free survival, time to treatment failure and overall survival. Clinical trial information: NCT02623972.

Citation Format: Overmoyer B, Goel S, Regan M, Hirshfield-Bartek J, Schlosnagel E, Yeh E, Qin L, Bellon J, Nakhlis F, Jacene H, Winer E. A phase 2 study of eribulin followed by doxorubicin and cyclophosphamide as preoperative therapy for HER2-negative inflammatory breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-01-07.

Abstract OT2-02-03: Pilot study of zirconium-89 bevacizumab positron emission tomography for imaging angiogenesis in patients with inflammatory breast carcinoma receiving preoperative chemotherapy

Background: Inflammatory breast cancer (IBC) continues to have a poor prognosis despite standard tri-modality treatment with chemotherapy, mastectomy and radiation. Current methods of assessing primary tumor response (i.e., clinical exam and breast magnetic resonance imaging [MRI]) are limited for distinguishing residual tumor from responsive disease because of persistent morphologic changes in the breast. Therefore, the inability to accurately assess tumor response during treatment often results in the continuation of ineffective systemic chemotherapy until definitive pathologic evaluation at mastectomy. IBC has a highly angiogenic phenotype which is believed to play a role in this tumor's aggressiveness. The novel radiotracer Zirconium-89 (89Zr)-bevacizumab was developed for imaging tumor angiogenesis with PET. We hypothesize that, as an imaging biomarker of angiogenesis, 89Zr-bevacizumab-PET/CT is a more specific noninvasive functional imaging modality for detecting the presence of tumor angiogenesis compared to current diagnostic methods and will serve as a predictor of response to therapy in patients (pts) with IBC.

Methods: Pts with newly diagnosed HER2neg IBC who will receive preoperative chemotherapy are eligible for this pilot study. 89Zr-bevacizumab-PET/CT, breast MRI and FDG-PET/CT are performed before, after 2 cycles, and at the completion of preoperative therapy. Biopsies of primary IBC tumors are obtained prior to and after 2 cycles of preoperative therapy. At the completion of preoperative therapy, pts proceed to mastectomy or biopsy if ineligible to proceed to mastectomy based on current standards for assessing primary tumor response, i.e., clinical exam, breast MRI and lack of systemic progression. At the time of mastectomy, standard evaluation of the surgical specimen will determine pathologic response of IBC to preoperative chemotherapy. A research sample will be collected if residual cancer is present at the time of mastectomy for histologic evaluation of tumor angiogenesis.

Objectives/Correlatives: The primary objective is to determine feasibility of 89Zr-bevacizumab-PET/CT imaging in pts with IBC. The primary endpoint is assessment of radiolabeling of chelated bevacizumab and number of successfully acquired 89Zr-bevacizumab-PET/CT scans. Correlative studies will be performed on IBC tissue to assess extent of angiogenesis including microvessel density, vessel diameter, vascular pericyte coverage and tumor VEGF levels. Secondary objectives are: 1) To determine if 89Zr-bevacizumab accumulation in primary IBC tumors correlates with the extent of angiogenesis determined by correlative analysis on IBC tissue; 2) To assess the predictive value of 89Zr-bevacizumab-PET/CT after 2 cycles and at the end of preoperative therapy for determining pathologic response at mastectomy as given by residual cancer burden.

Statistics: This is an accrual, not statistical based, feasibility justification. Planned sample size is 10 in order to make a preliminary statement about feasibility and ability for 89Zr-bevacizumab-PET/CT to serve as a surrogate in vivo biomarker of tumor angiogenesis and response to preoperative chemotherapy.

Clinical Trial Information: NCT01894451.

Citation Format: Jacene HA, Overmoyer B, Schlosnagle EJ, Abbott A, Yeh E, Paolino J, Goel S, Culhane A, Bellon JR, Nakhlis F, Hirshfield-Bartek J, Van den Abbeele A. Pilot study of zirconium-89 bevacizumab positron emission tomography for imaging angiogenesis in patients with inflammatory breast carcinoma receiving preoperative chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-02-03.

Abstract P6-07-30: Identifying novel glycosylation markers in Her2+ breast cancer using MALDI mass spectrometry

Breast cancer characterized by human epidermal growth factor receptor 2 (HER2) overexpression represents approximately 25-30% of all breast cancer cases. Many patients acquire resistance to current chemotherapies, leading to a more aggressive disease state with severe clinical outcomes. Lapatinib, a first generation tyrosine kinase inhibitor of HER2 and EGFR (epidermal growth factor receptor), is commonly used to treat HER2+ breast cancer. Resistance to lapatinib is steadily increasing among HER2+ patients, highlighting the need for therapy development. Identifying markers that predict treatment response or potential drug targets could enhance treatment efficacy and patient survival. To investigate this, we have used MALDI mass spectrometry to identify N-linked glycans specific to human breast cancer cell lines with known resistance and sensitivity to lapatinib treatment, JIMT-1 (resistant) HER2+ and BT474 (sensitive) HER2+. After different lapatinib dose and time course experiments, N-linked glycans were isolated and comparatively profiled by high resolution MALDI mass spectrometry. Differences in the levels of fucosylation and sialylation of glycans from sensitive and resistant cell lines, before and after treatment, were evaluated. In addition, mouse xenograft tumor tissues derived from the same cell lines treated with and without lapatinib were processed for on-tissue imaging of N-glycans using a MALDI imaging mass spectrometry approach. Tissues from HER2+ human breast tumors were also imaged with the same MALDI imaging approach. Cumulatively, these preliminary studies have identified novel glycosylation patterns associated with lapatinib treatment sensitivity and resistance.

Citation Format: Scott DA, Angel P, Xu H, Drake R, Yeh E. Identifying novel glycosylation markers in Her2+ breast cancer using MALDI mass spectrometry [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-07-30.

MicroRNA circulating in the early aftermath of motor vehicle collision predict persistent pain development and suggest a role for microRNA in sex-specific pain differences

BACKGROUND

Molecular mediators influencing the transition from acute to persistent musculoskeletal pain following common stress exposures such as motor vehicle collision (MVC) remain poorly understood. In this exploratory, proof of concept study, we compared circulating microRNA (miRNA) expression profiles in the early aftermath of MVC among individuals who did and did not subsequently develop persistent pain. Blood RNA samples were obtained from African American individuals (n = 53) who presented to the emergency department after MVC and were discharged to home after evaluation. The presence or absence of severe pain in the axial region, the most common and morbid region in which post-MVC pain occurs, was assessed 6 weeks following MVC via standardized questionnaire. miRNA expression was determined using miRNA-sequencing; nonparametric analyses were used to compare miRNA expression levels among individuals with and without persistent pain.

RESULTS

Thirty-two mature miRNA were differentially expressed (p < 0.05) in those with and without severe axial pain at 6 weeks. miR-135a-5p, a regulator of the serotonin receptor that is known to be stress-responsive, differed most significantly between groups (p = 3 × 10(-4)). This miRNA, and miR-3613-3p (p = 0.001) survived correction for multiple testing (FDR = 0.15) in this small sample. Interestingly, differentially expressed miRNA were enriched for X chromosome location. In secondary analyses, the eight X chromosome miRNA were (a) more significantly associated with axial pain in women than men, (b) expressed more highly in the peripheral blood of women than men, and (c) predicted in pathway analyses (DIANA miRPath v 2.0) to regulate neuronal and neuroendocrine pathways previously implicated in various pain pathologies.

CONCLUSIONS

These results show that circulating miRNA predict persistent severe axial pain after MVC and suggest that they may be involved in the pathogenesis of post-traumatic musculoskeletal pain. However, further studies are needed to determine if these miRNA play a direct causal role.

The prognostic significance of left ventricular ejection fraction in patients with advanced cancer treated in phase I clinical trials

BACKGROUND

New targeted agents may cause acute cardiac events. The purpose of our study was to investigate the incidence and the prognostic significance of left ventricular ejection fraction (LVEF) in phase I trials.

PATIENTS AND METHODS

Between October 2008 and September 2011, the records of 1166 consecutive patients with advanced cancer treated in the Phase I Clinic who underwent echocardiography were retrospectively reviewed.

RESULTS

Most of the patients were White (78%), and the most common tumor types were colorectal cancer and melanoma. Of 1166 patients, 177 (15.2%) patients had an LVEF of <50%. No difference in overall survival (OS) between patients with LVEF ≥ 50% and patients with LVEF < 50% was seen (median OS 7.4 versus 7.0 months, P = 0.84). Patients with LVEF ≤ 35% had shorter survival compared with those with LVEF between 35% and 50% (median 4.2 versus 8.0 months; P = 0.005). In multivariate analysis of patients with LVEF < 50%, independent factors predicting longer survival were LVEF > 35%, ≤2 prior systemic therapies, ≤2 metastatic sites, and normal lactate dehydrogenase and albumin levels.

CONCLUSION

Echocardiography would improve patient selection for enrollment in phase I clinical trials. These data suggest that it is safe to treat patients with LVEF between 35% and 50%.

Association of polymorphisms at the ADIPOR1 regulatory region with type 2 diabetes and body mass index in a Brazilian population with European or African ancestry

Association studies between ADIPOR1 genetic variants and predisposition to type 2 diabetes (DM2) have provided contradictory results. We determined if two single nucleotide polymorphisms (SNP c.-8503G>A and SNP c.10225C>G) in regulatory regions of ADIPOR1 in 567 Brazilian individuals of European (EA; N = 443) or African (AfA; N = 124) ancestry from rural (quilombo remnants; N = 439) and urban (N = 567) areas. We detected a significant effect of ethnicity on the distribution of the allelic frequencies of both SNPs in these populations (EA: -8503A = 0.27; AfA: -8503A = 0.16; P = 0.001 and EA: 10225G = 0.35; AfA: 10225G = 0.51; P < 0.001). Neither of the polymorphisms were associated with DM2 in the case-control study in EA (SNP c.-8503G>A: DM2 group -8503A = 0.26; control group -8503A = 0.30; P = 0.14/SNP 10225C>G: DM2 group 10225G = 0.37; control group 10225G = 0.32; P = 0.40) and AfA populations (SNP c.-8503G>A: DM2 group -8503A = 0.16; control group -8503A = 0.15; P = 0.34/SNP 10225C>G: DM2 group 10225G = 0.51; control group 10225G = 0.52; P = 0.50). Similarly, none of the polymorphisms were associated with metabolic/anthropometric risk factors for DM2 in any of the three populations, except for HDL cholesterol, which was significantly higher in AfA heterozygotes (GC = 53.75 +/- 17.26 mg/dL) than in homozygotes. We conclude that ADIPOR1 polymorphisms are unlikely to be major risk factors for DM2 or for metabolic/anthropometric measurements that represent risk factors for DM2 in populations of European and African ancestries.

Effect of polymorphisms of the MTHFR and APOE genes on susceptibility to diabetes and severity of diabetic retinopathy in Brazilian patients

Diabetes mellitus (DM) is a highly prevalent complex genetic disorder. There has been a worldwide effort in the identification of susceptibility genes for DM and its complications, and the 5-10-methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein-E (APOE) genes have been considered good candidate susceptibility genes to this condition. The objectives of the present study were to determine if the 677T MTHFR and epsilon2/epsilon3/epsilon4 APOE alleles are risk factors for DM and for severity of diabetic retinopathy (DR). A total of 248 individuals were studied: 107 healthy individuals and 141 diabetic patients (46 with type 1 diabetes and 95 with type 2 diabetes), who also had DR (81 with non-proliferative DR and 60 with proliferative DR). The polymorphisms were analyzed by PCR followed by digestion with restriction enzyme or the single-nucleotide primer extension method. No evidence of association between the 677TT genotype of MTHFR gene and DM [cases: TT = 10/95 (10.6%); controls: TT = 14/107 (13%)] or with severity of DR was observed [cases: TT = 5/60 (8.5%); controls: TT = 9/81 (11.1%); P > 0.05]. We also did not find evidence of an association between APOE alleles and proliferative DR (epsilon2, epsilon3 and epsilon4 in cases: 9, 76, and 15%, and in controls: 5, 88, and 12%, respectively) but the carriers of epsilon2 allele were more frequent among patients with type 2 DM and DR than in controls [cases: 15/95 (15.8%); controls: 7/107 (6.5%); P < 0.05]. Therefore, our results suggest that the epsilon2 allele/APOE might be a risk factor for diabetes in the Brazilian population.

Prevalence of Campylobacter spp., Escherichia coli, and Salmonella serovars in retail chicken, turkey, pork, and beef from the Greater Washington, D.C., area

A total of 825 samples of retail raw meats (chicken, turkey, pork, and beef) were examined for the presence of Escherichia coli and Salmonella serovars, and 719 of these samples were also tested for Campylobacter spp. The samples were randomly obtained from 59 stores of four supermarket chains during 107 sampling visits in the Greater Washington, D.C., area from June 1999 to July 2000. The majority (70.7%) of chicken samples (n = 184) were contaminated with Campylobacter, and a large percentage of the stores visited (91%) had Campylobacter-contaminated chickens. Approximately 14% of the 172 turkey samples yielded Campylobacter, whereas fewer pork (1.7%) and beef (0.5%) samples were positive for this pathogen. A total of 722 Campylobacter isolates were obtained from 159 meat samples; 53.6% of these isolates were Campylobacter jejuni, 41.3% were Campylobacter coli, and 5.1% were other species. Of the 212 chicken samples, 82 (38.7%) yielded E. coli, while 19.0% of the beef samples, 16.3% of the pork samples, and 11.9% of the turkey samples were positive for E. coli. However, only 25 (3.0%) of the retail meat samples tested were positive for Salmonella. Significant differences in the bacterial contamination rates were observed for the four supermarket chains. This study revealed that retail raw meats are often contaminated with food-borne pathogens; however, there are marked differences in the prevalence of such pathogens in different meats. Raw retail meats are potential vehicles for transmitting food-borne diseases, and our findings stress the need for increased implementation of hazard analysis of critical control point (HACCP) and consumer food safety education efforts.

A streamlined process to phenotypically profile heterologous cDNAs in parallel using yeast cell-based assays

To meet the demands of developing lead drugs for the profusion of human genes being sequenced as part of the human genome project, we developed a high-throughput assay construction method in yeast. A set of optimized techniques allows us to rapidly transfer large numbers of heterologous cDNAs from nonyeast plasmids into yeast expression vectors. These high- or low-copy yeast expression plasmids are then converted quickly into integration-competent vectors for phenotypic profiling of the heterologous gene products. The process was validated first by testing proteins of diverse function, such as p38, poly(ADP-ribose) polymerase-1, and PI 3-kinase, by making active-site mutations and using existing small molecule inhibitors of these proteins. For less well-characterized genes, a novel random mutagenesis scheme was developed that allows a combination selection/screen for mutations that retain full-length expression and yet reverse a growth phenotype in yeast. A broad range of proteins in different functional classes has been profiled, with an average yield for growth interference phenotypes of approximately 30%. The ease of manipulation of the yeast genome affords us the opportunity to approach drug discovery and exploratory biology on a genomic scale and shortens assay development time significantly.

Neuralized functions as an E3 ubiquitin ligase during Drosophila development

The Notch pathway is a widely studied means of intercellular signaling responsible for the determination of cell fate, cell differentiation, and boundary formation (reviewed in ). The main effectors of this pathway, Notch (N) and Delta (Dl), have been shown to function as a receptor and ligand, respectively. Genetic and phenotypic studies suggest that Neuralized (Neu), a RING finger protein, also plays a role within the N-Dl pathway, although its biochemical function is unknown. Here, we show that Neu is required at the plasma membrane for functional activity and that its RING finger domain acts as an E3 ubiquitin ligase. These data suggest that the role of Neu is to target components of the N-Dl pathway for ubiquitination, allowing for propagation and/or regulation of the signal.

Novel inhibitors of poly(ADP-ribose) polymerase/PARP1 and PARP2 identified using a cell-based screen in yeast

Multicellular organisms must have means of preserving their genomic integrity or face catastrophic consequences such as uncontrolled cell proliferation or massive cell death. One response is a modification of nuclear proteins by the addition and removal of polymers of ADP-ribose that modulate the properties of DNA-binding proteins involved in DNA repair and metabolism. These ADP-ribose units are added by poly(ADP-ribose) polymerase (PARP) and removed by poly(ADP-ribose) glycohydrolase. Although budding yeast Saccharomyces cerevisiae does not possess proteins with significant sequence similarity to the human PARP family of proteins, we identified novel small molecule inhibitors against two family members, PARP1 and PARP2, using a cell-based assay in yeast. The assay was based on the reversal of growth inhibition caused by the heterologous expression of either PARP1 or PARP2. Validation of the assay was achieved by showing that the growth inhibition was relieved by a mutation in a single residue in the catalytic site of PARP1 or PARP2 or exposure of yeast to a known PARP1 inhibitor, 6(5H)-phenanthridinone. In separate experiments, when a putative protein regulator of PARP activity, human poly(ADP-ribose) glycohydrolase, was coexpressed with PARP1 or PARP2, yeast growth was restored. Finally, the inhibitors identified by screening the yeast assay are active in a mammalian PARP biochemical assay and inhibit PARP1 and PARP2 activity in yeast cell extracts. Thus, our data reflect the strength of using yeast to identify small molecule inhibitors of therapeutically relevant gene families, including those that are not found in yeast, such as PARP. The resultant inhibitors have two critical uses (a) as leads for drug development and (b) as tools to dissect cellular function.

The role of the proteins Kar9 and Myo2 in orienting the mitotic spindle of budding yeast

BACKGROUND

Two genetic 'pathways' contribute to the fidelity of nuclear segregation during the process of budding in the yeast Saccharomyces cerevisiae. An early pathway, involving Kar9p and other proteins, orients the mitotic spindle along the mother-bud axis. Upon the onset of anaphase, cytoplasmic dynein provides the motive force for nuclear movement into the bud. Loss of either pathway results in nuclear-migration defects; loss of both is lethal. Here, to visualize the functional steps leading to correct spindle orientation along the mother-bud axis, we imaged live yeast cells expressing Kar9p and dynein as green fluorescent protein fusions.

RESULTS

Transport of Kar9p into the bud was found to require the myosin Myo2p. Kar9p interacted with microtubules through the microtubule-binding protein Bim1p and facilitated microtubule penetration into the bud. Once microtubules entered the bud, Kar9p provided a platform for microtubule capture at the bud cortex. Kar9p was also observed at sites of microtubule shortening in the bud, suggesting that Kar9p couples microtubule shortening to nuclear migration.

CONCLUSIONS

Thus, Kar9p provides a key link between the actin cytoskeleton and microtubules early in the cell cycle. A cooperative mechanism between Kar9p and Myo2p facilitates the pre-anaphase orientation of the spindle. Later, Kar9p couples microtubule disassembly with nuclear migration.

Dynamic positioning of mitotic spindles in yeast: role of microtubule motors and cortical determinants

In the budding yeast Saccharomyces cerevisiae, movement of the mitotic spindle to a predetermined cleavage plane at the bud neck is essential for partitioning chromosomes into the mother and daughter cells. Astral microtubule dynamics are critical to the mechanism that ensures nuclear migration to the bud neck. The nucleus moves in the opposite direction of astral microtubule growth in the mother cell, apparently being "pushed" by microtubule contacts at the cortex. In contrast, microtubules growing toward the neck and within the bud promote nuclear movement in the same direction of microtubule growth, thus "pulling" the nucleus toward the bud neck. Failure of "pulling" is evident in cells lacking Bud6p, Bni1p, Kar9p, or the kinesin homolog, Kip3p. As a consequence, there is a loss of asymmetry in spindle pole body segregation into the bud. The cytoplasmic motor protein, dynein, is not required for nuclear movement to the neck; rather, it has been postulated to contribute to spindle elongation through the neck. In the absence of KAR9, dynein-dependent spindle oscillations are evident before anaphase onset, as are postanaphase dynein-dependent pulling forces that exceed the velocity of wild-type spindle elongation threefold. In addition, dynein-mediated forces on astral microtubules are sufficient to segregate a 2N chromosome set through the neck in the absence of spindle elongation, but cytoplasmic kinesins are not. These observations support a model in which spindle polarity determinants (BUD6, BNI1, KAR9) and cytoplasmic kinesin (KIP3) provide directional cues for spindle orientation to the bud while restraining the spindle to the neck. Cytoplasmic dynein is attenuated by these spindle polarity determinants and kinesin until anaphase onset, when dynein directs spindle elongation to distal points in the mother and bud.

Neuralized functions cell autonomously to regulate Drosophila sense organ development

Neurogenic genes, including Notch and Delta, are thought to play important roles in regulating cell-cell interactions required for Drosophila sense organ development. To define the requirement of the neurogenic gene neuralized (neu) in this process, two independent neu alleles were used to generate mutant clones. We find that neu is required for determination of cell fates within the proneural cluster and that cells mutant for neu autonomously adopt neural fates when adjacent to wild-type cells. Furthermore, neu is required within the sense organ lineage to determine the fates of daughter cells and accessory cells. To gain insight into the mechanism by which neu functions, we used the GAL4/UAS system to express wild-type and epitope-tagged neu constructs. We show that Neu protein is localized primarily at the plasma membrane. We propose that the function of neu in sense organ development is to affect the ability of cells to receive Notch-Delta signals and thus modulate neurogenic activity that allows for the specification of non-neuronal cell fates in the sense organ.

Human granulocytic ehrlichiosis in Northern California: two case descriptions with genetic analysis of the Ehrlichiae

We report two cases of human granulocytic ehrlichiosis (HGE) that occurred in northern California in summer 1998. Patients had fever, malaise, and myalgia, reported tick bites, had moderate thrombocytopenia, and had normal or slightly elevated liver enzyme activities. Ehrlichial inclusions were observed in the blood of one patient, and HGE-agent DNA was amplified by PCR from both patients. Genetically, the strains resembled horse isolates from northern California. The close spatial and temporal proximity of the two new cases may be due to a nidus of infection in the area or heightened surveillance by local physicians.

Microtubule dynamics from mating through the first zygotic division in the budding yeast Saccharomyces cerevisiae

We have used time-lapse digital imaging microscopy to examine cytoplasmic astral microtubules (Mts) and spindle dynamics during the mating pathway in budding yeast Saccharomyces cerevisiae. Mating begins when two cells of opposite mating type come into proximity. The cells arrest in the G1 phase of the cell cycle and grow a projection towards one another forming a shmoo projection. Imaging of microtubule dynamics with green fluorescent protein (GFP) fusions to dynein or tubulin revealed that the nucleus and spindle pole body (SPB) became oriented and tethered to the shmoo tip by a Mt-dependent search and capture mechanism. Dynamically unstable astral Mts were captured at the shmoo tip forming a bundle of three or four astral Mts. This bundle changed length as the tethered nucleus and SPB oscillated toward and away from the shmoo tip at growth and shortening velocities typical of free plus end astral Mts (approximately 0.5 micrometer/min). Fluorescent fiduciary marks in Mt bundles showed that Mt growth and shortening occurred primarily at the shmoo tip, not the SPB. This indicates that Mt plus end assembly/disassembly was coupled to pushing and pulling of the nucleus. Upon cell fusion, a fluorescent bar of Mts was formed between the two shmoo tip bundles, which slowly shortened (0.23 +/- 0.07 micrometer/min) as the two nuclei and their SPBs came together and fused (karyogamy). Bud emergence occurred adjacent to the fused SPB approximately 30 min after SPB fusion. During the first mitosis, the SPBs separated as the spindle elongated at a constant velocity (0.75 micrometer/min) into the zygotic bud. There was no indication of a temporal delay at the 2-micrometer stage of spindle morphogenesis or a lag in Mt nucleation by replicated SPBs as occurs in vegetative mitosis implying a lack of normal checkpoints. Thus, the shmoo tip appears to be a new model system for studying Mt plus end dynamic attachments and much like higher eukaryotes, the first mitosis after haploid cell fusion in budding yeast may forgo cell cycle checkpoints present in vegetative mitosis.

Involvement of an actomyosin contractile ring in Saccharomyces cerevisiae cytokinesis

In Saccharomyces cerevisiae, the mother cell and bud are connected by a narrow neck. The mechanism by which this neck is closed during cytokinesis has been unclear. Here we report on the role of a contractile actomyosin ring in this process. Myo1p (the only type II myosin in S. cerevisiae) forms a ring at the presumptive bud site shortly before bud emergence. Myo1p ring formation depends on the septins but not on F-actin, and preexisting Myo1p rings are stable when F-actin is depolymerized. The Myo1p ring remains in the mother-bud neck until the end of anaphase, when a ring of F-actin forms in association with it. The actomyosin ring then contracts to a point and disappears. In the absence of F-actin, the Myo1p ring does not contract. After ring contraction, cortical actin patches congregate at the mother-bud neck, and septum formation and cell separation rapidly ensue. Strains deleted for MYO1 are viable; they fail to form the actin ring but show apparently normal congregation of actin patches at the neck. Some myo1Delta strains divide nearly as efficiently as wild type; other myo1Delta strains divide less efficiently, but it is unclear whether the primary defect is in cytokinesis, septum formation, or cell separation. Even cells lacking F-actin can divide, although in this case division is considerably delayed. Thus, the contractile actomyosin ring is not essential for cytokinesis in S. cerevisiae. In its absence, cytokinesis can still be completed by a process (possibly localized cell-wall synthesis leading to septum formation) that appears to require septin function and to be facilitated by F-actin.

Anti-AIDS agents. 30. Anti-HIV activity of oleanolic acid, pomolic acid, and structurally related triterpenoids

Oleanolic acid (1) was identified as an anti-HIV principle from several plants, including Rosa woodsii (leaves), Prosopis glandulosa (leaves and twigs), Phoradendron juniperinum (whole plant), Syzygium claviflorum (leaves), Hyptis capitata (whole plant), and Ternstromia gymnanthera (aerial part). It inhibited HIV-1 replication in acutely infected H9 cells with an EC50 value of 1.7 microg/mL, and inhibited H9 cell growth with an IC50 value of 21.8 microg/mL [therapeutic index (T. I.) 12.8]. Pomolic acid, isolated from R. woodsii and H. capitata, was also identified as an anti-HIV agent (EC50 1.4 microg/mL, T. I. 16.6). Although ursolic acid did show anti-HIV activity (EC50 2.0 microg/mL), it was slightly toxic (IC50 6.5 microg/mL, T. I. 3.3). A new triterpene (11) was also isolated from the CHCl3-soluble fraction of R. woodsii, though it showed no anti-HIV activity. The structure of 11 was determined to be 1beta-hydroxy-2-oxopomolic acid by spectral examination. Based on these results, we examined the anti-HIV activity of oleanolic acid- or pomolic acid-related triterpenes isolated from several plants. In addition, we previously demonstrated that derivatives of betulinic acid, isolated from the leaves of S. claviflorum as an anti-HIV principle, exhibited extremely potent anti-HIV activity. Accordingly, we prepared derivatives of oleanolic acid and evaluated their anti-HIV activity. Among the oleanolic acid derivatives, 18 demonstrated most potent anti-HIV activity, with an EC50 value of 0. 0005 microg/mL and a T. I. value of 22 400.

Astral microtubule dynamics in yeast: a microtubule-based searching mechanism for spindle orientation and nuclear migration into the bud

Localization of dynein-green fluorescent protein (GFP) to cytoplasmic microtubules allowed us to obtain one of the first views of the dynamic properties of astral microtubules in live budding yeast. Several novel aspects of microtubule function were revealed by time-lapse, three-dimensional fluorescence microscopy. Astral microtubules, about four to six in number for each pole, exhibited asynchronous dynamic instability throughout the cell cycle, growing at approximately 0.3-1.5 micron/min toward the cell surface then switching to shortening at similar velocities back to the spindle pole body (SPB). During interphase, a conical array of microtubules trailed the SPB as the nucleus traversed the cytoplasm. Microtubule disassembly by nocodozole inhibited these movements, indicating that the nucleus was pushed around the interior of the cell via dynamic astral microtubules. These forays were evident in unbudded G1 cells, as well as in late telophase cells after spindle disassembly. Nuclear movement and orientation to the bud neck in S/G2 or G2/M was dependent on dynamic astral microtubules growing into the bud. The SPB and nucleus were then pulled toward the bud neck, and further microtubule growth from that SPB was mainly oriented toward the bud. After SPB separation and central spindle formation, a temporal delay in the acquisition of cytoplasmic dynein at one of the spindle poles was evident. Stable microtubule interactions with the cell cortex were rarely observed during anaphase, and did not appear to contribute significantly to spindle alignment or elongation into the bud. Alterations of microtubule dynamics, as observed in cells overexpressing dynein-GFP, resulted in eventual spindle misalignment. These studies provide the first mechanistic basis for understanding how spindle orientation and nuclear positioning are established and are indicative of a microtubule-based searching mechanism that requires dynamic microtubules for nuclear migration into the bud.

Imaging green fluorescent protein fusion proteins in Saccharomyces cerevisiae

Tagging expressed proteins with the green fluorescent protein (GFP) from Aequorea victoria [1] is a highly specific and sensitive technique for studying the intracellular dynamics of proteins and organelles. We have developed, as a probe, a fusion protein of the carboxyl terminus of dynein and GFP (dynein-GFP), which fluorescently labels the astral microtubules of the budding yeast Saccharomyces cerevisiae. This paper describes the modifications to our multimode microscope imaging system [2,3], the acquisition of three-dimensional (3-D) data sets and the computer processing methods we have developed to obtain time-lapse recordings of fluorescent astral microtubule dynamics and nuclear movements over the complete duration of the 90-120 minute yeast cell cycle. This required low excitation light intensity to prevent GFP photobleaching and phototoxicity, efficient light collection by the microscope optics, a cooled charge-coupled device (CCD) camera with high quantum efficiency, and image reconstruction from serial optical sections through the 6 micron-wide yeast cell to see most or all of the astral molecules. Methods are also described for combining fluorescent images of the microtubules labeled with dynein-GFP with high resolution differential interference contrast (DIC) images of nuclear and cellular morphology [4], and fluorescent images of the chromosomes stained with 4,6-diamidino-2-phenylindole (DAPI) [5].

Identification of a mid-anaphase checkpoint in budding yeast

Activation of a facultative, dicentric chromosome provides a unique opportunity to introduce a double strand DNA break into a chromosome at mitosis. Time lapse video enhanced-differential interference contrast analysis of the cellular response upon dicentric activation reveals that the majority of cells initiates anaphase B, characterized by pole-pole separation, and pauses in mid-anaphase for 30-120 min with spindles spanning the neck of the bud before completing spindle elongation and cytokinesis. The length of the spindle at the delay point (3-4 microm) is not dependent on the physical distance between the two centromeres, indicating that the arrest represents surveillance of a dicentric induced aberration. No mid-anaphase delay is observed in the absence of the RAD9 checkpoint gene, which prevents cell cycle progression in the presence of damaged DNA. These observations reveal RAD9-dependent events well past the G2/M boundary and have considerable implications in understanding how chromosome integrity and the position and state of the mitotic spindle are monitored before cytokinesis.

Spindle dynamics and cell cycle regulation of dynein in the budding yeast, Saccharomyces cerevisiae

We have used time-lapse digital- and video-enhanced differential interference contrast (DE-DIC, VE-DIC) microscopy to study the role of dynein in spindle and nuclear dynamics in the yeast Saccharomyces cerevisiae. The real-time analysis reveals six stages in the spindle cycle. Anaphase B onset appears marked by a rapid phase of spindle elongation, simultaneous with nuclear migration into the daughter cell. The onset and kinetics of rapid spindle elongation are identical in wild type and dynein mutants. In the absence of dynein the nucleus does not migrate as close to the neck as in wild-type cells and initial spindle elongation is confined primarily to the mother cell. Rapid oscillations of the elongating spindle between the mother and bud are observed in wild-type cells, followed by a slower growth phase until the spindle reaches its maximal length. This stage is protracted in the dynein mutants and devoid of oscillatory motion. Thus dynein is required for rapid penetration of the nucleus into the bud and anaphase B spindle dynamics. Genetic analysis reveals that in the absence of a functional central spindle (ndcl), dynein is essential for chromosome movement into the bud. Immunofluorescent localization of dynein-beta-galactosidase fusion proteins reveals that dynein is associated with spindle pole bodies and the cell cortex: with spindle pole body localization dependent on intact microtubules. A kinetic analysis of nuclear movement also revealed that cytokinesis is delayed until nuclear translocation is completed, indicative of a surveillance pathway monitoring nuclear transit into the bud.

Green fluorescent protein as a vital marker and reporter of gene expression in Drosophila

We have used the green fluorescent protein (GFP) from the jellyfish Aequorea victoria as a vital marker/reporter in Drosophila melanogaster. Transgenic flies were generated in which GFP was expressed under the transcriptional control of the yeast upstream activating sequence that is recognized by GAL4. These flies were crossed to several GAL4 enhancer trap lines, and expression of GFP was monitored in a variety of tissues during development using confocal microscopy. Here, we show that GFP could be detected in freshly dissected ovaries, imaginal discs, and the larval nervous system without prior fixation or the addition of substrates or antibodies. We also show that expression of GFP could be monitored in intact living embryos and larvae and in cultured egg chambers, allowing us to visualize dynamic changes in gene expression during real time.