Sin Nombre Virus and the Emergence of Other Hantaviruses: A Review of the Biology, Ecology, and Disease of a Zoonotic Pathogen

Sin Nombre virus (SNV) is an emerging virus that was first discovered in the Four Corners region of the United States in 1993. The virus causes a disease known as Hantavirus Pulmonary Syndrome (HPS), sometimes called Hantavirus Cardiopulmonary Syndrome (HCPS), a life-threatening illness named for the predominance of infection of pulmonary endothelial cells. SNV is one of several rodent-borne hantaviruses found in the western hemisphere with the capability of causing this disease. The primary reservoir of SNV is the deer mouse (Peromyscus maniculatus), and the virus is transmitted primarily through aerosolized rodent excreta and secreta. Here, we review the history of SNV emergence and its virus biology and relationship to other New World hantaviruses, disease, treatment, and prevention options.

Effects of acute femoral head ischemia on the growth plate and metaphysis in a piglet model of Legg-Calvé-Perthes disease

OBJECTIVE

To determine the effects of acute (≤7 days) femoral head ischemia on the proximal femoral growth plate and metaphysis in a piglet model of Legg-Calvé-Perthes disease (LCPD). We hypothesized that qualitative and quantitative histological assessment would identify effects of ischemia on endochondral ossification.

DESIGN

Unilateral femoral head ischemia was surgically induced in piglets, and femurs were collected for histological assessment at 2 (n = 7) or 7 (n = 5) days post-ischemia. Samples were assessed qualitatively, and histomorphometry of the growth plate zones and primary spongiosa was performed. In a subset of samples at 7 days, hypertrophic chondrocytes were quantitatively assessed and immunohistochemistry for TGFβ1 and Indian hedgehog was performed.

RESULTS

By 2 days post-ischemia, there was significant thinning of the proliferative and hypertrophic zones, by 63 μm (95% CI -103, -22) and -19 μm (95% CI -33, -5), respectively. This thinning persisted at 7 days post-ischemia. Likewise, at 7 days post-ischemia, the primary spongiosa was thinned to absent by an average of 311 μm (95% CI -542, -82) in all ischemic samples. TGFβ1 expression was increased in the hypertrophic zone at 7 days post-ischemia.

CONCLUSIONS

Alterations to the growth plate zones and metaphysis occurred by 2 days post-ischemia and persisted at 7 days post-ischemia. Our findings suggest that endochondral ossification may be disrupted at an earlier time point than previously reported and that growth disruption may occur in the piglet model as occurs in some children with LCPD.

Quantitative T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in an in vivo piglet model of Legg-Calvé-Perthes disease

OBJECTIVE

To determine if the quantitative MRI techniques T2 and T1ρ mapping are sensitive to ischemic injury to epiphyseal cartilage in vivo in a piglet model of Legg-Calvé-Perthes disease using a clinical 3T MRI scanner. We hypothesized that T2 and T1ρ relaxation times would be increased in the epiphyseal cartilage of operated vs contralateral-control femoral heads 1 week following onset of ischemia.

DESIGN

Unilateral femoral head ischemia was surgically induced in eight piglets. Piglets were imaged 1 week post-operatively in vivo at 3T MRI using a magnetization-prepared 3D fast spin echo sequence for T2 and T1ρ mapping and a 3D gradient echo sequence for cartilage segmentation. Ischemia was confirmed in all piglets using gadolinium contrast-enhanced MRI. Median T2 and T1ρ relaxation times were measured in the epiphyseal cartilage of the ischemic and control femoral heads and compared using paired t-tests. Histological assessment was performed on a subset of five piglets.

RESULTS

T2 and T1ρ relaxation times were significantly increased in the epiphyseal cartilage of the operated vs control femoral heads (ΔT2 = 11.9 ± 3.7 ms, 95% CI = [8.8, 15.0] ms, P < 0.0001; ΔT1ρ = 12.8 ± 4.1 ms, 95% CI = [9.4, 16.2] ms, P < 0.0001). Histological assessment identified chondronecrosis in the hypertrophic and deep proliferative zones within ischemic epiphyseal cartilage.

CONCLUSIONS

T2 and T1ρ mapping are sensitive to ischemic injury to the epiphyseal cartilage in vivo at clinical 3T MRI. These techniques may be clinically useful to assess injury and repair to the epiphyseal cartilage to better stage the extent of ischemic damage in Legg-Calvé-Perthes disease.

Optimization of histologic grading schemes in spontaneous and surgically-induced murine models of osteoarthritis

OBJECTIVE

To compare the Osteoarthritis Research Society International (OARSI) and Articular Cartilage Structure (ACS) grading schemes applied to multiple and single sections, along with additional histologic measures, in two mouse models of Osteoarthritis (OA).

METHODS

Six coronal histologic stifle joint sections were collected from 40 C57BL/6J mice, including aged mice with spontaneous OA (approximately 18 months of age; n = 15) and young (12-week-old) mice that either underwent destabilization of the medial meniscus (DMM) surgery (n = 15) or sham surgery (n = 10). Sections were evaluated with the standard OARSI (0-6) scheme, a modified OARSI scheme, the ACS (0-12) scheme, histomorphometry of cartilage and bone, and scoring of osteophytes (0-3) and synovial hyperplasia (0-3). Principal components analysis (PCA) was used to determine the features explaining the greatest variability among the sections.

RESULTS

The grading schemes performed similarly when applied to a single mid-coronal section or six total coronal sections per joint. OARSI grading produced similar results when applied to hematoxylin and eosin or toluidine blue-stained sections. Aged mice had higher severity scores in the LTP than DMM mice (mid-coronal OARSI grade aged = 2.3 and DMM = 1.1, p = 0.0006; ACS grade aged = 4.1 and DMM = 1.6, p = 0.0024). PCA resulted in retention of four factors that accounted for 78.4% of the total variance. Factor 1 (36.4%) included the OARSI grade, ACS grade, Toluidine blue grade, articular cartilage area and thickness and the osteophyte grade.

CONCLUSIONS

Grading of a single mid-coronal section using either the OARSI or ACS schemes combined with osteophyte and histomorphometric measures can consistently define OA severity in mice.

Abstract P2-09-30: A gene expression signature that predicts for trastuzumab response in HER2+ breast cancer

Background: Approximately 15-20% of breast cancers overexpress HER2. These patients are eligible for trastuzumab in combination with chemotherapy. However, some patients are extreme responders to single agent trastuzumab and we wanted to identify differences in cancer gene expression that could predict response to single agent trastuzumab.

Methods: We performed paired-end RNAseq on an isogenic cellular model of trastuzumab sensitivity and resistance. We reasoned that the isogenic nature of the cellular clones used in this study would enrich for differentially-expressed genes (DEGs) that were associated with response to single-agent trastuzumab. DEGs where chosen based upon either i) large fold changes in resistant vs. sensitive clones, ii) high frequency in human HER2+ breast cancers, or iii) were found to be enriched with other DEGs in signaling pathways selected by Ingenuity Pathway Analysis (IPA). DEGs were further scrutinized based upon associations with overall survival (OS) in HER2+ human breast cancers. The resulting genes were validated using qPCR and in several independent sample sets containing gene expression profiles of human breast cancers.

Results: Discovery: RNAseq yielded 3,241 statistically-significant DEGs. We used two independent filtering pipelines to obtain 175 DEGs. Ingenuity Pathway Analysis found signaling pathways associated with eukaryotic initiation factor, lysine specific demethylase 5B, and estrogen receptor alpha to be enriched in DEGs associated with trastuzumab resistance. Of these DEGs, six genes correlated with a statistically significant change in OS in the training dataset, and were validated by qPCR in the cell lines used for the analysis. We further determined that the six-gene signature was a negative predictor of overall survival in HER2+ breast cancer patients whose cancers carried at least one DEG. Validation: Using independent cohorts from TCGA and the website KMplot.com, we validated the predictive power of the six-gene signature. Of the 47 HER2+ patients from TCGA, eight patients carried two more DEGs, while 39 carried ≤ 1 DEG. Although the numbers are small, of the 8 patients followed for four or more years, only one patient was alive as compared with 7 out of 39 patients without the signature. Similarly, Kaplan Meier analysis of gene expression data from KMplot.com revealed that only 1 out of 23 patients (4.3%) who carried high mean expression of the six-gene signature were free of distant metastases after 87 months, compared to 4 out of 43 patients (9.3%) from the cohort carrying low mean expression of the six-gene signature. In both validation cohorts, the six DEG signature was not predictive in HER2-negative breast cancers.

Discussion: Patients whose tumors lack this gene expression signature are more likely to experience a favorable response to trastuzumab therapy. This signature requires validation in a clinical cohort treated with trastuzumab monotherapy.

Citation Format: Abukhdeir AM, Najor MS, Turturro SB, Armstrong AR, McDonald A, Fogg L, Cobleigh MA. A gene expression signature that predicts for trastuzumab response in HER2+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-30.

The prevalence in Canada of drug-resistant tubercle bacilli in newly discovered untreated patients with tuberculosis

During the period February 1963 to September 1964, the incidence of strains of tubercle bacilli excreted by newly diagnosed, previously untreated patients with tuberculosis in Canada that were resistant to the major antituberculosis drugs, viz. streptomycin, para-aminosalicylic acid and isoniazid, was 4.8%. Resistance to a single drug (3.8%) was observed more commonly than was resistance to two drugs (0.9%) or to all three drugs (0.3%), and the drug most frequently involved in this regard was streptomycin (1.8%). Data for the province of Ontario were almost the same as those for Canada. These data are compared with results of surveys in other countries and it is concluded that while drug-resistant tubercle bacilli do not constitute a major problem in Canada at present, awareness of this potential hazard should be maintained.