Death receptor-based enrichment of Cas9-expressing cells.

BACKGROUND: The CRISPR/Cas9 genome editing system has greatly facilitated and expanded our capacity to engineer mammalian genomes, including targeted gene knock-outs. However, the phenotyping of the knock-out effect requires a high DNA editing efficiency. RESULTS: Here, we report a user-friendly strategy based on the extrinsic apoptosis pathway that allows enrichment of a polyclonal gene-edited cell population, by selecting Cas9-transfected cells that co-express dominant-negative mutants of death receptors. The extrinsic apoptosis pathway can be triggered in many mammalian cell types, and ligands are easy to produce, do not require purification and kill much faster than the state-of-the-art selection drug puromycin. Stringent assessment of our advanced selection strategy via Sanger sequencing, T7 endonuclease I (T7E1) assay and direct phenotyping confirmed a strong and rapid enrichment of Cas9-expressing cell populations, in some cases reaching up to 100 % within one hour. Notably, the efficiency of target DNA cleavage in these enriched cells reached high levels that exceeded the reliable range of the T7E1 assay, a conclusion that can be generalized for editing efficiencies above 30 %. Moreover, our data emphasize that the insertion and deletion pattern induced by a specific gRNA is reproducible across different cell lines. CONCLUSIONS: The workflow and the findings reported here should streamline a wide array of future low- or high-throughput gene knock-out screens, and should largely improve data interpretation from CRISPR experiments.

Randomized trial of adjunctive topiramate therapy in infants with refractory partial seizures.

OBJECTIVE: To evaluate the efficacy and safety of adjunctive topiramate (sprinkle capsules or oral liquid) in reducing daily rates of partial-onset seizures (POS) in infants with refractory POS. METHODS: In this double-blind, placebo-controlled, parallel-group, international study, infants (n = 149) with clinical or EEG evidence of refractory POS were randomly allocated (1:1:1:1) to receive adjunctive topiramate 5, 15, or 25 mg/kg/d or placebo for 20 days. The primary variable was the median percentage reductions in daily POS rate from baseline to final assessment as recorded on a 48-hour video-EEG. RESULTS: Of the 149 infants (mean age 12 months) included in the intent-to-treat analysis set, 130 completed the study. Median percentage reduction from baseline in daily POS rate was not significantly different (p = 0.97) between topiramate 25 mg/kg (20.4%) and placebo (13.1%). Lower doses were not formally tested, but nominal p values for comparisons with placebo were not significant (15-mg/kg/d dose: p = 0.97; 5-mg/kg/d dose: p = 0.91). Treatment-emergent fever, diarrhea, vomiting, anorexia, weight decrease, somnolence, and viral infection occurred more frequently (> or = 10% difference) with topiramate than with placebo. CONCLUSION: In infants aged 1-24 months, topiramate 5, 15, or 25 mg/kg/d was not effective as adjunctive treatment for refractory partial-onset seizures. No new safety concerns associated with topiramate use were noted. CLASSIFICATION OF EVIDENCE: This interventional study provides Class I evidence that topiramate 5, 15, or 25 mg/kg/d compared with placebo does not significantly reduce seizure rates in infants aged 1 month to 2 years with refractory partial-onset seizures.

Continual monitoring of intraepithelial lymphocyte immunophenotype and clonality is more important than snapshot analysis in the surveillance of refractory coeliac disease.

OBJECTIVE: An aberrant immunophenotype and monoclonality of intraepithelial lymphocytes (IELs) are frequently found in refractory coeliac disease (RCD). However, the utility of continual monitoring of IEL immunophenotype and clonality in the surveillance of RCD remains to be studied. DESIGN: The diagnostic and follow-up biopsies from 33 patients with CD, 7 with suspected RCD, 41 with RCD and 20 with enteropathy-associated T cell lymphoma (EATL) (including 11 evolved from RCD) were investigated by CD3epsilon/CD8 double immunohistochemistry and PCR-based clonality analysis of the rearranged T cell receptor (TCR) genes. RESULTS: An aberrant immunophenotype (CD3epsilon(+)CD8(-) IELs > or =40%) and monoclonality were detected occasionally in CD biopsies, either transiently in patients with CD not compliant with a gluten-free diet or in those who subsequently developed suspected RCD, RCD or EATL. In contrast, the aberrant immunophenotype and monoclonality were found in 30 of 41 (73%) and 24 of 37 (65%) biopsies, respectively, at the time of RCD diagnosis. Among the patients with RCD who did not show these abnormalities in their diagnostic biopsies, 8 of 10 (80%) and 5 of 11 (45%) cases gained an aberrant immunophenotype and monoclonality, respectively, during follow-up. Irrespective of whether detected in diagnostic or follow-up biopsies, persistence of both abnormalities was characteristic of RCD. Importantly, the presence of concurrent persistent monoclonality and aberrant immunophenotype, especially > or =80% CD3epsilon(+)CD8(-) IELs, was a strong predictor of EATL development in patients with RCD (p=0.001). CONCLUSIONS: Continual monitoring of both immunophenotype and clonality of IELs is more important than snapshot analysis for RCD diagnosis and follow-up, and could provide a useful tool for surveillance of patients at risk of EATL.

Role of polymerase chain reaction and immunocytochemistry in the cytological assessment of lymphoid proliferations.

BACKGROUND: Fine-needle aspiration cytology (FNAC) is used as a screening test to evaluate lymphadenopathy. The combined use of genetic analysis and flow cytometry for immunophenotyping has increased the accuracy of diagnosis and correct categorisation of lymphomas on cytological preparations. AIM: To show the utility of immunocytochemistry and polymerase chain reaction (PCR) in the evaluation of cytological preparations of lymph nodes. METHODS: Fine needle aspirates were obtained from 33 patients (initial presentation, n = 27; recurrence, n = 6). Routine examination was undertaken using immunocytochemistry and DNA PCR to detect clonality and specific translocations. The cytodiagnosis and subclassification of lymphoma was correlated with histological diagnosis in the available follow-up biopsies. RESULTS: 14 patients had a cytological diagnosis of non-Hodgkin's lymphoma (NHL), 4 had suspected NHL, 2 had atypical lymphoid proliferation and 13 had reactive hyperplasia. A World Health Organization (WHO) subtype was suggested in 8 patients. Incorporating the results of immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) gene rearrangements enabled diagnosis of lymphoma in 17 patients, including 5 of the 6 patients suspected to have NHL or an atypical lymphoid proliferation. Identification of the translocations t (14;18) and t (2;5) helped WHO categorisation in 3 of the patients. The cytological findings were confirmed in 12 out of the 13 patients for whom histological follow-up was available. Seven of the 18 lymphoma patients were managed without a subsequent biopsy. We made one false-positive diagnosis of B-cell NHL on cytology. CONCLUSION: The use of immunocytochemistry and PCR is valuable in the definitive diagnosis and subtyping of malignant lymphomas on cytological preparations. The use of these techniques may avoid lymph node biopsies in some cases and allow definitive treatment based on aspirate findings alone.

Computerized diagnostic decision support system for the classification of preinvasive cervical squamous lesions.

Previous studies have revealed considerable interobserver and intraobserver variation in the histological classification of preinvasive cervical squamous lesions. The aim of the present study was to develop a decision support system (DSS) for the histological interpretation of these lesions. Knowledge and uncertainty were represented in the form of a Bayesian belief network that permitted the storage of diagnostic knowledge and, for a given case, the collection of evidence in a cumulative manner that provided a final probability for the possible diagnostic outcomes. The network comprised 8 diagnostic histological features (evidence nodes) that were each independently linked to the diagnosis (decision node) by a conditional probability matrix. Diagnostic outcomes comprised normal; koilocytosis; and cervical intraepithelial neoplasia (CIN) I, CIN II, and CIN III. For each evidence feature, a set of images was recorded that represented the full spectrum of change for that feature. The system was designed to be interactive in that the histopathologist was prompted to enter evidence into the network via a specifically designed graphical user interface (i-Path Diagnostics, Belfast, Northern Ireland). Membership functions were used to derive the relative likelihoods for the alternative feature outcomes, the likelihood vector was entered into the network, and the updated diagnostic belief was computed for the diagnostic outcomes and displayed. A cumulative probability graph was generated throughout the diagnostic process and presented on screen. The network was tested on 50 cervical colposcopic biopsy specimens, comprising 10 cases each of normal, koilocytosis, CIN I, CIN II, and CIN III. These had been preselected by a consultant gynecological pathologist. Using conventional morphological assessment, the cases were classified on 2 separate occasions by 2 consultant and 2 junior pathologists. The cases were also then classified using the DSS on 2 occasions by the 4 pathologists and by 2 medical students with no experience in cervical histology. Interobserver and intraobserver agreement using morphology and using the DSS was calculated with kappa statistics. Intraobserver reproducibility using conventional unaided diagnosis was reasonably good (kappa range, 0.688 to 0.861), but interobserver agreement was poor (kappa range, 0.347 to 0.747). Using the DSS improved overall reproducibility between individuals. Using the DSS, however, did not enhance the diagnostic performance of junior pathologists when comparing their DSS-based diagnosis against an experienced consultant. However, the generation of a cumulative probability graph also allowed a comparison of individual performance, how individual features were assessed in the same case, and how this contributed to diagnostic disagreement between individuals. Diagnostic features such as nuclear pleomorphism were shown to be particularly problematic and poorly reproducible. DSSs such as this therefore not only have a role to play in enhancing decision making but also in the study of diagnostic protocol, education, self-assessment, and quality control.

Serous carcinoma arising in an adenofibroma of the endometrium.

A serous carcinoma and endometrial intraepithelial carcinoma were encountered in an endometrial adenofibroma in a 61-year-old woman. The carcinoma involved the myometrium and cervix (stage IIa). To our knowledge, this is the third documented case of an adenocarcinoma and the first serous carcinoma involving a uterine adenofibroma.

Soft tissue, pelvic, and urinary bladder leiomyosarcoma as second neoplasm following hereditary retinoblastoma.

This report describes two patients who developed leiomyosarcomas, one involving the subcutaneous tissue of the thigh and the pelvic soft tissues and the other the urinary bladder, following hereditary retinoblastoma 36 and 38 years earlier, respectively. There is an increased risk of the development of sarcoma, most commonly osteosarcoma, as a second malignancy following hereditary retinoblastoma. Leiomyosarcoma developing as a second malignancy has rarely been reported and most have occurred in the field of previous radiotherapy. The literature on leiomyosarcoma occurring as a second neoplasm following retinoblastoma is reviewed.

Soft tissue myoepithelioma: a case report.

Myoepitheliomas are tumours composed predominantly or exclusively of myoepithelial cells. They are well described, especially within the salivary gland, but their occurrence in soft tissues is less well known and this often results in diagnostic problems. We report a case involving the deep soft tissues of the lower neck behind the clavicle. Grossly, the tumour was well circumscribed with solid and cystic areas. Histology showed a richly vascularised tumour composed of bland round, ovoid or spindle-shaped cells. Various growth patterns were present including solid, nested, microcystic and trabecular arrangements. In some areas there was an alveolar pattern with tumour cells lining fibrous septae. Immunohistochemistry showed diffuse strong positivity for S100 protein, calponin, vimentin and glial fibrillary acidic protein and focal positivity for epithelial membrane antigen, 34betaE12 and AE1/AE3, in keeping with myoepithelial differentiation. Electron microscopy revealed tumour cells surrounded by basal lamina with subplasmalemmal densities and containing cytoplasmic myofilaments. This case report highlights the rare occurrence of myoepitheliomas in deep soft tissues. Pathologists should be aware of this and should consider a myoepithelioma in the differential diagnosis of a soft tissue spindle cell neoplasm.

New methods of resolution and purification of racemic and diastereomeric amino alcohol derivatives using boric acid and chiral 1,1'-bi-2-naphthol.

Resolution of the racemic amino alcohol derivatives 1-6 is readily achieved to obtain enantiomerically enriched compounds using chiral 1,1'-bi-2-naphthol and boric acid in solvents such as CH(3)CN, THF, and MeOH. Purification of the diastereomeric mixture 7 has also been carried out following this method. The corresponding intermediate ammonium borate complexes were also characterized by X-ray diffraction methods.

Thyroglobulin immunoreactivity in lymph node histiocytes: a potential diagnostic pitfall.

AIMS: Strong thyroglobulin immunoreactivity within sinus histiocytes in a lymph node draining a papillary thyroid carcinoma was observed in a recent case. This prompted the investigation of whether thyroglobulin immunoreactivity is common in regional lymph nodes in cases of thyroid malignancy. METHODS: Eighty seven lymph nodes were studied from 21 cases of thyroid malignancy. These comprised papillary carcinoma (n = 12), follicular carcinoma (n = 4), medullary carcinoma (n = 3), and one case each of squamous and anaplastic carcinoma. Eleven cervical lymph nodes from patients with no evidence of thyroid disease were included as controls. Sections were stained with a monoclonal antibody against thyroglobulin. RESULTS: In the cases of thyroid malignancy, 32 of 87 lymph nodes showed positive staining for thyroglobulin of histiocytes within the subcapsular and medullary sinuses. In an additional four cases, there was positive staining of lymph within lymphatic channels. Positivity was present in at least one node in 15 of 21 cases. There was no positivity in the control cases. There was no correlation between the size of the primary tumour and the presence of thyroglobulin positivity. CONCLUSIONS: Positive staining with antithyroglobulin occurs not uncommonly in sinus histiocytes in lymph nodes draining thyroid tumours. This positivity could be the result of the destruction of normal thyroid follicles, with the release of thyroglobulin, which is taken up by histiocytes, which subsequently drain to local lymph nodes. Pathologists should be aware of this phenomenon and should be careful not to interpret this as metastatic tumour.