RNase L-induced bodies sequester subgenomic flavivirus RNAs and re-establish host RNA decay

Subgenomic flavivirus RNAs (sfRNAs) are structured RNA elements encoded in the 3'-UTR of flaviviruses that promote viral infection by inhibiting cellular RNA decay machinery. Herein, we analyze the production of sfRNAs using single-molecule RNA fluorescence in situ hybridization (smRNA-FISH) and super-resolution microscopy during West Nile virus, Zika virus, or Dengue virus serotype 2 infection. We show that sfRNAs are initially localized diffusely in the cytosol or in processing bodies (P-bodies). However, upon activation of the host antiviral endoribonuclease, Ribonuclease L (RNase L), nearly all sfRNAs re-localize to antiviral biological condensates known as RNase L-induced bodies (RLBs). RLB-mediated sequestration of sfRNAs reduces sfRNA association with RNA decay machinery in P-bodies, which coincides with increased viral RNA decay. These findings establish a role of RLBs in promoting viral RNA decay, demonstrating the complex host-pathogen interactions at the level of RNA decay and biological condensation.

Mechanisms and consequences of mRNA destabilization during viral infections

During viral infection there is dynamic interplay between the virus and the host to regulate gene expression. In many cases, the host induces the expression of antiviral genes to combat infection, while the virus uses "host shut-off" systems to better compete for cellular resources and to limit the induction of the host antiviral response. Viral mechanisms for host shut-off involve targeting translation, altering host RNA processing, and/or inducing the degradation of host mRNAs. In this review, we discuss the diverse mechanisms viruses use to degrade host mRNAs. In addition, the widespread degradation of host mRNAs can have common consequences including the accumulation of RNA binding proteins in the nucleus, which leads to altered RNA processing, mRNA export, and changes to transcription.

G3BP1-dependent condensation of translationally inactive viral RNAs antagonizes infection

G3BP1 is an RNA binding protein that condenses untranslating messenger RNAs into stress granules (SGs). G3BP1 is inactivated by multiple viruses and is thought to antagonize viral replication by SG-enhanced antiviral signaling. Here, we show that neither G3BP1 nor SGs generally alter the activation of innate immune pathways. Instead, we show that the RNAs encoded by West Nile virus, Zika virus, and severe acute respiratory syndrome coronavirus 2 are prone to G3BP1-dependent RNA condensation, which is enhanced by limiting translation initiation and correlates with the disruption of viral replication organelles and viral RNA replication. We show that these viruses counteract condensation of their RNA genomes by inhibiting the RNA condensing function of G3BP proteins, hijacking the RNA decondensing activity of eIF4A, and/or maintaining efficient translation. These findings argue that RNA condensation can function as an intrinsic antiviral mechanism, which explains why many viruses inactivate G3BP proteins and suggests that SGs may have arisen as a vestige of this antiviral mechanism.

Dosimetric Risk Estimation of Chest Wall Pain Following 5-Fraction Lung Stereotactic Body Radiotherapy

PURPOSE/OBJECTIVE(S)

Development of chest wall pain (CWP) following lung stereotactic body radiotherapy (SBRT) is a known toxicity, particularly for peripheral lesions. While CW V30 has been most consistently associated with development of post-SBRT CWP, existing series included heterogeneous dose-fractionation regimens, most commonly 48-54 Gy in 3-4 fractions. The present study aims to identify clinical and dosimetric variables associated with development of CWP among patients treated with 5 fraction lung SBRT.

MATERIALS/METHODS

Intradepartmental quality assurance database of SBRT patients was queried to identify lung targets treated to a minimum of 45 Gy in 5 fractions. Retrospective chart and plan reviews were performed on these cases to collect patient, tumor, and treatment-related data, selecting for patients with peripheral lesions (any histology), and recording presence or absence of CWP during or following SBRT. Patients with less than 6 months of post-SBRT clinical follow-up were excluded. The CW was defined as a 2 cm expansion of the ipsilateral lung (inclusive of intercostal musculature, ribs, and superficial soft tissue). Logistic regression analyses were performed on continuous and nominal data to determine statistically significant (p<0.05) correlations between clinical (age, gender, known osteopenia/osteoporosis, diabetes, prior thoracic radiotherapy, lesion distance to CW), treatment (interval of SBRT delivery, dose prescribed), and dosimetric (Dose to 0.1/1/5/10cc; V30, V40) factors with CWP.

RESULTS

Between February 2011 and January 2022, 93 patients were identified for inclusion in the present analysis, treated to 100 total lesions in 99 courses of treatment. Median patient age was 75 years (range 34-90), 48 (52%) were female, and 29 (of 99 treatment courses; 29%) had received prior thoracic radiotherapy. Median SBRT dose was 50 Gy (45-60), delivered over a median of 9 days (4-18). At a median post-SBRT follow-up of 21 months, 11 patients developed CWP at a median of 9 months post-SBRT (0-32). Statistically significant correlations were identified between CWP and known pre-existing osteopenia or osteoporosis, target distance to CW, and CW D0.1cc, D1cc, D5cc, and D10cc, but not CW V30 or V40. Crude risk of CWP for selected clinically practical dose-volume thresholds are presented in Table 1: CONCLUSION: For patients treated with lung SBRT in 5 fractions, dose to CW volume thresholds appears to correlate more closely than V30 or V40 for CWP estimation. Further investigation and validation of optimal CW volume thresholds, as well as integration of pre-existing condition clinical factors in risk estimation, appears warranted.

Single-cell analysis of RNase L-mediated mRNA decay

Ribonuclease L (RNase L) is a mammalian endoribonuclease that initiates the mass degradation of cellular mRNAs in response to double-stranded RNA or viral infection. The kinetic rate of mRNA decay upon RNase L activation has been elusive because RNase L is heterogeneously activated with respect to time in individual cells. Herein, we describe a method using immunofluorescence combined with single-molecule fluorescence in situ hybridization (smFISH) to determine single-cell mRNA decay rates upon RNase L activation. Using these approaches, we deduce that the rate of mRNA decay upon RNase L activation is extremely rapid, whereby the half-life of stable mRNAs such as GAPDH mRNA is reduced to ∼15 minutes in individual cells. This allows for RNase L to degrade nearly every mRNA in a cell in less than 1 hour, which is much faster than the decay rate that would be derived using bulk measurement techniques for mRNA levels, such as qRT-PCR. These single-cell approaches can generally be employed to resolve mRNA decay kinetics in additional contexts.

An Engineered Monovalent Anti-TNF-α Antibody with pH-Sensitive Binding Abrogates Immunogenicity in Mice following a Single Intravenous Dose

Therapeutic Abs directed toward TNF-α display significant immunogenicity in humans, frequently leading to lower serum concentrations of the Ab that are associated with lower treatment efficacy. The enhanced incidence of immunogenicity observed with this class of therapeutics may be mediated by the expression of TNF-α as a homotrimer, both as a soluble serum protein and as a membrane-associated protein (mTNF-α) on the surface of dendritic cells. The TNF-α homotrimer enables the formation of polyvalent Ab-TNF-α immune complexes (ICs) that enhance binding to FcR and neonatal FcR. Polyvalent ICs and Ab bound to mTNF-α on the surface of dendritic cells can internalize, traffic to the lysosomes, and be processed for presentation by MHC molecules. To diminish immunogenicity caused by trafficking of ICs and mTNF-α to the lysosomes, we engineered a monovalent format of adalimumab with pH-sensitive binding to TNF-α. The engineered variant, termed AF-M2637, did not cross-link TNF-α trimers and consequently formed small, nonprecipitating ICs only. AF-M2637 bound TNF-α with high affinity at pH 7.4 (EC50 = 1.1 nM) and displayed a significantly faster dissociation rate than adalimumab at pH 6.0. No immune response to AF-M2637 was detected in mice following a single i.v. dose. In contrast, rapid immunization was detected following the injection of a single i.v. dose of adalimumab, monovalent adalimumab, or the bivalent form of the pH-sensitive variant. These data suggest that ICs and mTNF-α both contribute to the immunogenicity of adalimumab in mice and provide a general strategy for engineering less immunogenic therapeutic TNF-α Abs.

Prenatal infection with Mycoplasma pulmonis in rats exaggerates the angiotensin II pressor response in adult offspring

Exposure to different stressors in utero is linked to adult diseases such as obesity and hypertension. In this study, the impact of prenatal infection (PNI) on adult body weight and cardiovascular function was evaluated using a naturally occurring rodent pathogen, Mycoplasma pulmonis (MP). Pregnant Sprague-Dawley rats were infected with MP on gestational day 14 and gave birth naturally. Adult PNI offspring weighed more than controls, but resting mean arterial pressure (MAP) was unchanged. Subcutaneous injection of angiotensin II (10 μg/kg) elicited a rise in MAP that was greater in both male and female PNI offspring compared with controls (P < 0.03). The accompanying reflex bradycardia was similar to the controls, suggesting that PNI induced baroreflex dysfunction. Subcutaneous nicotine administration, a potent cardiorespiratory stimulus, also elicited a transient rise in MAP that was generally greater in the PNI group, but the change in MAP from baseline was only significant in the PNI females compared with controls (P < 0.03). Elevated body weight and cardiovascular reactivity in the PNI offspring was associated with an increase in the ratio of hypothalamic corticotrophin-releasing hormone receptors type 1 to type 2 gene expression in both sexes compared with controls. These findings support previous studies demonstrating that PNI induces alterations in cardiovascular function and body weight. Yet, unlike previous studies utilizing other models of PNI (e.g., endotoxin), MP PNI did not induce resting hypertension. Thus, our study provides a foundation for future studies evaluating the cardiovascular risks of offspring exposed to microbial challenges in utero.

Undergraduates achieve learning gains in plant genetics through peer teaching of secondary students

This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non-majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS) students through a case study curriculum to discover the cause of a green tomato variant. The curriculum explored plant reproduction and genetic principles, highlighting variation in heirloom tomato fruits to reinforce the concept of the genetic basis of phenotypic variation. HS students were taught additional activities related to mole-cular biology techniques not included in the MS curriculum. We measured undergraduates' learning outcomes using pre/postteaching content assessments and the course final exam. Undergraduates showed significant gains in understanding of topics related to the curriculum they taught, compared with other course content, on both types of assessments. Undergraduates who taught HS students scored higher on questions specific to the HS curriculum compared with undergraduates who taught MS students, despite identical lecture content, on both types of assessments. These results indicate the positive effect of service-learning peer-teaching experiences on undergraduates' content knowledge, even for non-science major students.

Ultrasound-guided tandem placement for low-dose-rate brachytherapy in advanced cervical cancer minimizes risk of intraoperative uterine perforation

OBJECTIVES

Tandem placement as part of low-dose-rate (LDR) brachytherapy boost for cervical cancer may be complicated by uterine perforation. The objective of this study was to describe a 10-year experience of using intraoperative ultrasound guidance in an attempt to minimize the risk of uterine perforation.

METHODS

Operative and inpatient records were reviewed to identify cases in which intraoperative ultrasound guidance was employed in order to assist tandem placement, and to determine whether clinical or radiographic findings subsequently suggested uterine perforation. Demographic factors were collected in order to determine the baseline risk of perforation within this population.

RESULTS

Between 1998 and 2008, 71 patients underwent 110 ultrasound-guided placements of tandem applicators. The median age was 48 (range, 26-88) years, and 20% were older than 60 years. Disease stage was FIGO IB1 (n = 10), IB2 (n = 13), IIA (n = 4), IIB (n = 19), IIIA (n = 2), IIIB (n = 16), IVA (n = 5) and IVB (n = 2). The median gravidity was 3 (range 1-10) and median parity was 3 (range 0-10). Seven patients had a preimplant history of pelvic infection, four had a history of intrauterine contraceptive device use, and 10 had a prior history of Cesarean section delivery. Only one patient experienced infection that may have been attributable to tandem placement-associated uterine perforation. At median survivor follow-up of 34 months, 19 patients had died. The estimated 3-year disease-free and overall survival rates for the entire population were 60% and 66%, respectively.

CONCLUSIONS

Within the present population, intraoperative ultrasound guidance of tandem placement was associated with no confirmed cases of uterine perforation.

Long term disease control outcomes for partial breast irradiation using MammoSite brachytherapy

Abstract #5145

Purpose: To describe 4-year local and ipsilateral breast recurrence-free intervals, overall freedom from disease failure, and disease-specific and overall survivals in a cohort of MammoSite Brachytherapy (MBT) patients with mature follow-up, treated at a single institution over a 6-year period.&#x2028; Methods and Materials: An analysis of MBT cases was performed using prospectively collected quality assurance database, departmental chart review, and electronic medical records. Patient-, tumor-, treatment-, and outcome-specific data were extracted and recorded into a research database. Eligible patients were required to have &gt;6 months post-MBT follow-up. Local tumor failure was defined as pathologically-proven recurrence within 2 cm of the resected tumor bed, with all other ipsilateral breast recurrences (excluding axilla or internal mammary nodal failures) defined as ipsilateral breast failures. Any local, ipsilateral breast, nodal, or distant failure was censored for overall freedom from failure.&#x2028; Results: From 2004 through 2008, 115 MBT patients have been treated, of which 104 were eligible for the present analysis. Median patient age was 62 years (range 25–86). Primary tumors included ductal carcinoma in situ (DCIS) for 20 patients, T1a (12), T1b (31), T1c (34), and T2 (7). Lymph nodes were assessed in 94 patients (including all patients with invasive carcinomas), and revealed pN0 disease in 85 patients, pN1(mic) (3), and pN1a (6). Histologies of invasive carcinomas were ductal in 68 patients, lobular (3), mixed ductal/lobular (3), mucinous/colloid (7), medullary (2), and tubular (1). At a median follow up of 45.7 months (range 7.3-71.4), 6 patients have experienced disease recurrence, including 4 within the ipsilateral breast. Three patients with ipsilateral breast recurrence underwent salvage mastectomy, two of whom remain without evidence of disease recurrence at 56 and 14 months, respectively. Seven patients have died, 3 of or with recurrent breast cancer. Estimated 4-year outcomes for the entire cohort were: local tumor control 100%, ipsilateral breast control 97.0% (95% CI, 93.6%-100%), overall freedom from failure 93.8% (88.5%-99.5%), disease specific survival 97.8% (94.8%-100%) and overall survival 92.7% (87.2%-98.6%).&#x2028; Conclusions: The present study demonstrates low rates of local and ipsilateral breast disease failure in a well-defined cohort of MBT patients with mature follow-up.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5145.

Declining immune function in children and adolescents with hemophilia and HIV infection: effects on neuropsychological performance. Hemophilia Growth and Development Study

OBJECTIVE

To determine whether declines in immune functioning are associated with changes in neuropsychological performance in children and adolescents with hemophilia who are infected with the human immunodeficiency virus (HIV).

METHODS

Participants were 333 males with hemophilia, ages 6-19 years at entry. A baseline and four annual neuropsychological evaluations were given. A longitudinal growth curves analysis of data was performed to detect changes associated with declining immune function. The cohort was stratified into four groups: (1) HIV- (n = 126); (2) HIV+, average of first two and last two CD4 counts > or = 200, (n = 106; High CD4 group); (3) HIV+, average first two counts > or = 200, average last two counts < 200 (n = 41; CD4 Drop group); and (4) HIV+, average first two and last two counts < 200 (n = 60; Low CD4 group).

RESULTS

There were significant differences among the four groups over time in nonverbal intelligence, perceptual/performance skills, nonverbal memory, academic achievement, and language. The Low CD4 group consistently showed the greatest decrement in performance. On measures showing a practice effect for repeated measurements, the Low CD4 group participants' scores remained stable over time, suggesting opposing effects of practice and HIV-related declines. Lowered academic performance relative to IQ was found in all groups.

CONCLUSIONS

Declines in neuropsychological functioning are directly related to declines in immune functioning in HIV+ children, adolescents, and young adults with hemophilia. Hemophilia itself may be a risk factor for academic underachievement.

Attention in HIV-infected children: results from the Hemophilia Growth and Development Study

Attentional functioning was examined in three groups of 7- to 19-year-old male participants with hemophilia: (1) HIV seronegative controls (HIV-, N = 66), (2) HIV seropositive participants with CD4+ lymphocyte counts greater than or equal to 200 (HIV+ CD4+ > or = 200, N = 79), and (3) severely immune suppressed HIV seropositive participants (HIV+ CD4+ < 200, N = 28). Two measures sensitive to attention deficits were used: the Continuous Performance Test (CPT) and the Span of Apprehension (Span). On the CPT, there was a decrement in attention in both HIV+ groups, as indexed by an increase in false alarm rate from Block 1 to Block 3, that was not present in the HIV- group. The longer the HIV+ children were required to sustain attention to the CPT, the more they responded to the incorrect stimulus. This effect decreased as age increased. Span percent correct and latency to correct were associated with the presence of a premorbid history of intracerebral hemorrhage, but were not sensitive to HIV status or degree of immune suppression in the HIV+ children, suggesting morbidity related to hemophilia. The remaining CPT and Span variables--hit rate, sensitivity, latency, percent correct, and latency to correct--showed the expected associations with age, but none showed conclusive associations with HIV status or immune suppression in the HIV+ participants.

Heparan preserves intestinal perfusion after hemorrhage and resuscitation

BACKGROUND

Multiple system organ failure (MOF) remains a major source of morbidity and mortality in trauma patients. Despite restoration of central hemodynamics, intestinal hypoperfusion can persist. Mucosal ischemia and barrier breakdown are factors in the genesis of MOF. Heparan sulfate is a gycosaminoglycan similar to heparin, but with minimal anticoagulant properties. As an adjunct to resuscitation, it improves immunologic function and restores mucosal oxygenation and function. We hypothesized that resuscitation with heparan following hemorrhage wound prevents intestinal hypoperfusion.

MATERIALS AND METHODS

In vivo videomicroscopy was used to study small intestine microcirculation in rats. Animals were hemorrhaged to 50% of baseline mean arterial pressure (MAP) and maintained there. Resuscitation was initiated when the return of 10% shed blood was required to keep MAP at 50%. Animals received either heparan (7 mg/kg/1 ml saline) or saline (1 ml) followed by the remaining shed blood and an equal volume of saline. MAP, cardiac output (CO), A1 arteriole diameters, and flow were determined.

RESULTS

Resuscitation of the saline control group resulted in normal MAP with elevation of CO to 25-40% above baseline. The heparan group had return of MAP but only a moderate increase in CO (7-15%). Saline resuscitation led to progressive deterioration in A1 diameters and flow. The addition of heparan prevented delayed A1 constriction and significantly improved perfusion.

CONCLUSIONS

Heparan prior to resuscitation improved intestinal perfusion, despite a relative reduction in CO. Improvement in nutrient blood flow may protect the mucosal barrier, reducing the incidence of MOF, and suggests that heparan may be useful in resuscitation of trauma patients.

Cognitive/neuropsychological studies of children with a schizophrenic disorder

This article summarizes a series of cognitive/neuropsychological studies of children with schizophrenia. One set of studies, which surveyed a broad range of neuropsychological functions, revealed no evidence that children with schizophrenia are consistently impaired in sensory, perceptual, or language functions. Rather, the studies showed that children with schizophrenia performed poorly on tasks requiring sensory, perceptual, and language processing that made extensive demands on information-processing capacity. A second series of studies, which examined visual information processing by manipulating the processing demands of span of apprehension tasks, yielded similar findings. The key characteristic of tasks that elicit impaired performance in children with schizophrenia is that the task makes extensive demands on processing resources. This suggests that these children have limited information-processing capacity. Three hypotheses are proposed concerning the cognitive processes that are impaired in children with schizophrenia: (1) the cognitive processes that seem to be impaired in these children are part of a more general, hierarchically organized attention system; (2) the component processes of the system are subserved by different brain structures; and (3) the structures are part of a network that includes the frontal lobe and thalamus in interaction with the reticular activating system.

Reactivity of monoclonal antibody E5 with endotoxin. I. Binding to lipid A and rough lipopolysaccharides

The murine IgM monoclonal antibody (mAb) E5 was produced by a hybridoma derived from spleen cells of a mouse immunized with the J5 rough mutant of Escherichia coli O111:B4. In a multicenter randomized placebo-controlled clinical trial, E5 has been shown to reduce significantly the mortality and morbidity of patients with Gram-negative sepsis. The characteristics of E5 binding to endotoxin were studied in vitro. We report here the results of binding to an extensive panel of rough lipopolysaccharide (LPS) and lipid A preparations. Using standard immunologic techniques, including enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA), as well as an antibody capture assay using immobilized antibody and a chromogenic Limulus amebocyte lysate (LAL) detection system, E5 was shown to bind to all rough LPS (chemotypes Ra through Re from Salmonella minnesota and E. coli J5) and lipid A preparations tested. E5 displayed a Kd for Ra LPS of approximately 6.5 nM. These results confirm and extend those reported previously and provide evidence that E5 binds specifically to lipid A and to the lipid A moiety of rough LPS.

Symptom development in childhood onset schizophrenia

Symptom development from birth to 12 years of age was examined in 18 children who met DSM-III criteria for schizophrenia with onset before 10 years of age. Using a follow-back design, symptom development was rated at each of four age levels using a DSM-III Symptom Rating Scale and the Achenbach Child Behavior Checklist. Results revealed a gradual developmental unfolding of a broad spectrum of symptoms affecting social, cognitive, sensory and motor functioning and beginning many years before the appearance of schizophrenic symptoms--usually in early infancy. Prior to 6 years of age, severe language deficits and motor development problems were each found in 72% of the sample and symptoms of infantile autism were found in 39% of the sample. Onset of schizophrenia occurred at an earlier age for children with a history of autistic symptoms during infancy than for other children in the sample. Schizophrenia as defined by DSM-III was entirely absent before 6 years of age.

Emergency department screening for unsuspected carbon monoxide exposure

Carbon monoxide (CO) is the leading toxic cause of death in the United States today. Unsuspected exposure to this gas will sometimes result in clinically significant, but undiagnosed, toxicity. A high incidence of such unsuspected exposures would make screening for these worthwhile among high-risk populations. We conducted a two-part study to determine the value of screening for unsuspected CO exposure in a population of patients presenting to an emergency department. The first part of our study involved the prospective screening of ED patients using CO breath analysis, regardless of their chief complaint. In the second part, COHGB levels of all patients who underwent arterial blood gas analysis during the study period were reviewed retrospectively. Of 1,038 patients screened by this combined approach, only 29 (2.8%) had abnormal CO breath readings and/or COHGB levels. Of a condensed subgroup of 152 patients defined retrospectively by chief complaint, eight (5.3%) had abnormal values. We conclude that routine screening of ED patients for unsuspected CO exposure is not practical. Although yield increases when patients are screened in a more selective manner on the basis of chief complaint, such an increase still does not appear to justify the screening process.

A longitudinal study of respiratory viruses and bacteria in the etiology of acute otitis media with effusion

We analyzed data from a 14-year longitudinal study of respiratory infections in young children to determine the relative importance of viral respiratory infection and nasopharyngeal colonization with Streptococcus pneumoniae and Haemophilus influenzae as factors influencing the occurrence of acute otitis media with effusion. The incidence of this disorder was increased in children with viral respiratory infections (average relative risk, 3.2; P less than 0.0001). Infection with respiratory syncytial virus, influenza virus (type A or B), and adenovirus conferred a greater risk of otitis media than did infection with parainfluenza virus, enterovirus, or rhinovirus. Colonization of the nasopharynx with Str. pneumoniae or H. influenzae had a lesser effect on the incidence of the disease (average relative risk; 1.5; P less than 0.01). Infections with the viruses more closely associated with acute otitis media (respiratory syncytial virus, adenovirus, and influenza A or B) were correlated with an increased risk of recurrent disease. Prevention of selected otitis-associated viral infections should reduce the incidence of this disease.