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Dive into the research topics where Christopher L. Owens is active.

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Featured researches published by Christopher L. Owens.


Theoretical and Applied Genetics | 2007

Wine grape (Vitis vinifera L.) color associates with allelic variation in the domestication gene VvmybA1

Patrice This; Thierry Lacombe; Molly Cadle-Davidson; Christopher L. Owens

During the process of crop domestication and early selection, numerous changes occur in the genetic and physiological make-up of crop plants. In grapevine (Vitis vinifera) numerous changes have occurred as a result of human selection, including the emergence of hermaphroditism and greatly increased variation in berry color. This report examines the effect of human selection on variable skin color by examining the variation present in the gene VvmybA1, a transcriptional regulator of anthocyanin biosynthesis. In over 200 accessions of V. vinifera, the insertion of the retroelement Gret1 in the promoter region of VvmybA1 was in strong association with the white-fruited phenotype. This retroelement was inserted at the same location for each individual in which it was present. Additional polymorphisms in the VvmybA1 gene were also strongly associated with red or pink fruited accessions, including variation that was generated by the excision of Gret1 from the promoter of VvmybA1. Differences in nucleotide diversity were observed between the white and pigmented alleles of VvmybA1, suggesting that the white allele arose only once or a limited number of times. Rarely, association of Gret1 with the white fruited phenotype was not observed, suggesting that the white phenotype can also be obtained through mutation in additional genes. These results provide evidence that variation in one transcriptional regulator has generated an allelic series strongly associated with fruit color variation in cultivated grapevine. These findings provide information about the evolution of grapes since domestication and have direct implications for the regulation of fruit and wine quality of this important crop plant.


Food Chemistry | 2011

Polyphenolic profiles detected in the ripe berries of Vitis vinifera germplasm

Zhenchang Liang; Christopher L. Owens; Gan-Yuan Zhong; Lailiang Cheng

Polyphenolic profiles in the berry samples of 344 European grape (Vitis vinifera) cultivars were evaluated for two consecutive years. These cultivars represent a diverse collection of V. vinifera germplasm maintained at the USDA-Agricultural Research Service Vitis Clonal Repository in Davis of California, USA. A total of 36 polyphenolic compounds, including 16 anthocyanins, 6 flavonols, 6 flavanols, 6 hydroxycinnamic acids and 2 hydroxybenzoic acids, were identified via HPLC-MS and quantified by HPLC-DAD. The mean contents for anthocyanins, flavanols, flavonols, hydroxycinnamic acids and hydroxybenzoic acids were 0.946 (coloured cultivars), 0.147, 0.043, 0.195 and 0.016mgg(-1) FW, respectively. On average, wine grapes had higher concentrations than had table grapes for all of these compounds except hydroxycinnamic acids. Berry colours affected the total contents of anthocyanins, but not others. Positive correlations (0.151-0.535) were found among these groups of compounds. As expected, these groups of compounds were all negatively correlated with berry weight.


Cancer Cytopathology | 2013

The Johns Hopkins Hospital template for urologic cytology samples: parts II and III: improving the predictability of indeterminate results in urinary cytologic samples: an outcomes and cytomorphologic study.

Christopher VandenBussche; Srividya Sathiyamoorthy; Christopher L. Owens; Frances H. Burroughs; Dorothy L. Rosenthal; Hui Guan

Urine cytology represents a major portion of testing volume in many cytopathology laboratories.


Cancer Cytopathology | 2013

A review of reporting systems and terminology for urine cytology

Christopher L. Owens; Christopher VandenBussche; Frances H. Burroughs; Dorothy L. Rosenthal

Urine cytology continues to play an important role in the diagnosis and management of urothelial carcinoma, a common cancer of adults with significant morbidity and mortality. Because of its high sensitivity for high‐grade urothelial tumors, including lesions that may be cystoscopically occult, urine cytology nicely compliments cystoscopic examination, a method that detects most low‐grade tumors. Over the decades, several reporting schemes for urine cytology have been published in the literature, each of which has relative strengths and weaknesses. Unlike cervical cytology, there has not been widespread acceptance and use of any particular reporting scheme for urine cytology studies. Thus, terminology and criteria for urine cytology reporting are not uniform among pathologists, which can frustrate clinicians and hinders interlaboratory comparisons. Cancer (Cancer Cytopathol) 2013;121:9–14


Cancer Cytopathology | 2013

The Johns Hopkins Hospital template for urologic cytology samples: part I-creating the template.

Dorothy L. Rosenthal; Christopher VandenBussche; Frances H. Burroughs; Srividya Sathiyamoorthy; Hui Guan; Christopher L. Owens

The most important indicator for urologic surgeons at The Johns Hopkins Hospital to have a patient undergo cystoscopy is a cytologic diagnosis of high‐grade urothelial carcinoma. The template was designed to standardize diagnostic categories so clinicians can manage their patients uniformly. The template was based in part on the Bethesda System for cervical cytology.


Cancer Cytopathology | 2011

Improved preoperative definitive diagnosis of papillary thyroid carcinoma in FNAs prepared with both ThinPrep and conventional smears compared with FNAs prepared with ThinPrep alone

Martin H. Luu; Andrew H. Fischer; Latha Pisharodi; Christopher L. Owens

ThinPrep (TP) liquid‐based preparations are increasingly being used in nongynecologic specimens. Few studies have evaluated TP as a sole diagnostic modality in the setting of thyroid fine‐needle aspiration (T‐FNA). Herein, the authors evaluate the usefulness of TP as a sole diagnostic modality in a nonsplit sample.


Cancer | 2007

Deep fibromatosis (desmoid tumor): cytopathologic characteristics, clinicoradiologic features, and immunohistochemical findings on fine-needle aspiration.

Christopher L. Owens; Rajni Sharma; Syed Z. Ali

Deep fibromatosis or desmoid tumor (DF/DT) is a low‐grade, soft tissue lesion that is notable for its infiltration and local recurrence and its inability to metastasize. Although the histologic features of DF/DT are well described, there is a paucity of literature regarding cytologic findings.


Archives of Pathology & Laboratory Medicine | 2007

Distinguishing Prostatic From Colorectal Adenocarcinoma on Biopsy Samples: The Role of Morphology and Immunohistochemistry

Christopher L. Owens; Jonathan I. Epstein; George J. Netto

CONTEXT Poorly differentiated carcinoma on prostate or colorectal biopsy can occasionally present a diagnostic challenge in determining tumor source especially in locally advanced colorectal carcinoma (CRCa) or prostate carcinoma (PCa). Such determination can affect prognosis and therapy. OBJECTIVE To evaluate the role of morphology and immunohistochemistry in the previously mentioned setting. DESIGN Surgical pathology and consultation records. Hematoxylin-eosin sections were reviewed in 16 cases (11 PCa, 5 CRCa). Immunohistochemistry for 9 markers was performed in 15 cases. RESULTS Dirty necrosis, seen in 5 (100%) of 5 CRCa and 2 (18%) of 11 PCa cases, and the presence of columnar cells with basal nuclei, seen in 5 (100%) of 5 CRCa and 1 (9%) of 11 PCa cases, appear to be the most useful morphologic parameters. Immunohistochemistry confirmed the value of prostate-specific antigen (PSA), CDX2, cytokeratin (CK) 20, and beta-catenin in the differential of CRCa (0% PSA+, 60% CDX2+, 80% CK20+, and 100% beta-catenin+) versus PCa (80% PSA+, 0% CDX2+, 10% CK20+, and 0% beta-catenin+). P501S had a similar sensitivity as PSA in detecting PCa (80%). Two (20%) of 10 PCa cases were positive for 1 of the 2 markers but not the other. P501S was negative in all 5 cases of CRCa. CONCLUSIONS P501S is a useful marker in this setting when included together with PSA, CDX2, CK20, and beta-catenin. P501S labels a subset of PCa cases that are negative for PSA. Dirty necrosis and/or columnar cells with basal nuclei could also be of help.


Acta Cytologica | 2011

Atypical follicular cells with equivocal features of papillary thyroid carcinoma is not a low-risk cytologic diagnosis.

Martin H. Luu; Andrew H. Fischer; Thomas J. Stockl; Latha Pisharodi; Christopher L. Owens

Objective: To determine whether or not significant differences in the risk of malignancy exist between subgroups of atypical follicular cells in The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in patients who underwent surgical resection. Study Design: Between 2004 and 2009, consecutive thyroid fine-needle aspirates at our institutions with a cytologic diagnosis of ‘atypical follicular cells’ were retrieved and subclassified using the diagnosis and diagnostic comment as: (1) atypical follicular cells with equivocal features of papillary carcinoma [cannot exclude papillary thyroid carcinoma (PTC)] and (2) atypical follicular cells, other patterns. The risks of malignancy for excised nodules were calculated and comparisons were made between these subgroups. Categorical analysis was performed using a 2-tailed Fisher’s exact test, and p < 0.05 was considered statistically significant. Results: A total of 7,072 thyroid fine-needle aspiration cases were retrieved, with 1,542 (21.8%) having a histologic follow-up. There were 222 (3.1%) cases of ‘atypical follicular cells’, with 127 (57.2%) having a histologic correlation and 33 having confirmed malignancies. Atypical follicular cells, cannot exclude PTC, have a significantly higher risk of malignancy than atypical follicular cells, other patterns (45.8 vs. 13.9%, p < 0.01). Conclusions: Atypical follicular cells with equivocal features of papillary carcinoma is not a low-risk cytologic diagnosis.


American Journal of Clinical Pathology | 2010

Thyroid Bed Fine-Needle Aspiration Experience at a Large Tertiary Care Center

Justin A. Bishop; Christopher L. Owens; Chung H. Shum; Syed Z. Ali

Fine-needle aspiration (FNA) of thyroid bed (TB) lesions is a common diagnostic modality in monitoring patients for recurrent cancer after a thyroidectomy. To elucidate the value of TB FNA, we reviewed our experience at The Johns Hopkins Hospital, Baltimore, MD. We identified 57 TB FNA specimens from 50 patients. Of the patients, 36 were being followed up for papillary carcinoma, 7 for medullary carcinoma, 4 for follicular carcinoma (1 also had papillary carcinoma), and 1 for poorly differentiated neuroendocrine carcinoma; 3 had previous benign diagnoses. TB FNA yielded diagnostic material in 49 of 57 cases. Of 37 malignant or atypical FNA samples, 32 had surgical follow-up; 30 of 32 were confirmed malignant. The FNA result was benign in 12 of 57, including 6 cases of benign thyroid and 1 case of parathyroid tissue. Immunohistochemical staining was contributory in 5 of 57 cases. TB FNA is a highly reliable tool for diagnosing recurrent thyroid carcinoma. Residual benign thyroid and parathyroid tissue are potential pitfalls; awareness of these and judicious use of immunohistochemical staining can prevent misdiagnoses.

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Andrew H. Fischer

University of Massachusetts Medical School

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Vighnesh Walavalkar

University of Massachusetts Medical School

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Syed Z. Ali

Johns Hopkins University

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Aruna Kamineni

Group Health Research Institute

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Azadeh Stark

Henry Ford Health System

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Daniel Peterson

University of Massachusetts Medical School

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Diana S. M. Buist

Group Health Research Institute

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Terry S. Field

University of Massachusetts Medical School

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Tyler R. Ross

Group Health Cooperative

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