Standardization of biological dyes and stains: pitfalls and possibilities

Biocompatibility of three different root canal sealers, experimental study

OBJECTIVES

This study was assessed the biocompatibility of three different root canal sealers (Well-Root St, GuttaFlow Bioseal, and AH-Plus) following implantation in rat subcutaneous tissues, using histopathological immunohistochemical analysis.

METHODS

Four groups of eighty-four male rats each underwent subcutaneous dorsal implantation of a polyethylene tube, either empty or filled. Tissues were collected, fixed, and processed for histological analysis after 7, 15, and 30 d. Slides were photographed and digitally processed to identify lymphocytes and macrophages using Cluster of differentiation 3 (CD3) and cluster of differentiation 68 (CD68) markers, respectively. P was set at 0.05, when lymphocyte and macrophage infiltration was compared between groups and observation times using one-way analysis of variance (ANOVA).

RESULTS

Histopathological analysis of all groups revealed an inflammatory reaction followed by the emergence of a fibrous capsule after 7 days. After 30 days, the thickness of the fibrous capsule and the inflammatory response subsided. CD3 staining for immunohistochemical analysis revealed that the AH-Plus group had the highest mean percentage of lymphocyte infiltration at 7 and 15 days, followed by the Well-Root St, GuttaFlow Bioseal, and Control groups. After 30 days, no discernible difference was observed between the groups in terms of the mean percentage of lymphocyte infiltration. After 7, 15, and 30 days, there was a significant difference in the mean percentage of macrophage infiltration across the groups, as demonstrated by CD68 staining. After 7, 15, and 30 days, the AH-Plus group had the highest mean percentage of macrophage infiltration, followed by the Well-Root St. and GuttaFlow Bioseal groups, while the control group had the lowest mean percentage.

CONCLUSION

All observational periods showed minimal inflammatory reactions to GuttaFlow Bioseal. After subcutaneous tissue implantation in a rat model, the initial inflammatory reactions to Well-Root St and AH-Plus had abated by day 30, and all tested sealers had outstanding biocompatibility.

Frozen Block Tissue Staining for Eye Structure of Zebrafish Embryo

Histology is a technique used to study the morphology of cell structures by cutting samples into thin sections. Histological cross-section and staining are the techniques needed to visualize the morphology of cell tissues. A suitable tissue staining experiment was created to observe changes in the retinal layer in zebrafish embryos. Zebrafish have a human-like visual system, retina, and eye structures. Due to the small size of zebrafish and undeveloped bones in the embryonic stage, the resistance through cross-section is inevitably small. Here, we present optimized protocol changes in eye tissue of zebrafish using frozen blocks.

Artificial Intelligence-Based Prediction of Recurrence after Curative Resection for Colorectal Cancer from Digital Pathological Images

BACKGROUND

To develop an artificial intelligence-based model to predict recurrence after curative resection for stage I-III colorectal cancer from digitized pathological slides.

PATIENTS AND METHODS

In this retrospective study, 471 consecutive patients who underwent curative resection for stage I-III colorectal cancer at our institution from 2004 to 2015 were enrolled, and 512 randomly selected tiles from digitally scanned images of hematoxylin and eosin-stained tumor tissue sections were used to train a convolutional neural network. Five-fold cross-validation was used to validate the model. The association between recurrence and the model's output scores were analyzed in the test cohorts.

RESULTS

The area under the receiver operating characteristic curve of the cross-validation was 0.7245 [95% confidence interval (CI) 0.6707-0.7783; P < 0.0001]. The score successfully classified patients into those with better and worse recurrence free survival (P < 0.0001). Multivariate analysis revealed that a high score was significantly associated with worse recurrence free survival [odds ratio (OR) 1.857; 95% CI 1.248-2.805; P = 0.0021], which was independent from other predictive factors: male sex (P = 0.0238), rectal cancer (P = 0.0396), preoperative abnormal carcinoembryonic antigen (CEA) level (P = 0.0216), pathological T3/T4 stage (P = 0.0162), and pathological positive lymph node metastasis (P < 0.0001).

CONCLUSIONS

The artificial intelligence-based prediction model discriminated patients with a high risk of recurrence. This approach could help decision-makers consider the benefits of adjuvant chemotherapy.

Establishment and Fractionation of Metastatic Axillary Lymph Node Cell Suspension for Determination of Protein Expression Levels of Nuclear cFOS and Cytosolic TGFβ1 from Breast Cancer Patients

Background

Metastatic Axillary Lymph Node (mALN) status is currently the most important prognostic factor in the management of primary breast cancer (BC). Thus, development of specimens which enable identification of new mALN markers, involved in the progression of the disease, are of considerable interest. The specific aim of this work was to describe the method of establishment of Metastatic Axillary Nodal Cell Suspension and its fractionation, termed Fractionated Nodal Cell Suspension (FNCS), into nuclear and cytosolic extracts to enable determination of protein expression levels of nuclear cFOS and cytosolic Transforming Growth Factor β1 (TGFβ1) in BC patients.

Results

To standardize the procedure, HeLa cells were successfully fractionated into nuclear/cytosolic extracts with confirmed presence of nuclear cFOS and cytosolic TGFβ1 proteins. Subsequently, the ALN Cell Suspension specimens were obtained and further fractionated from a pilot sample of six ALN tissue pairs, mALN versus autologous normal ALN (nALN), dissected from invasive BC patients. The mALN/nALN results revealed overexpression of both nuclear cFOS and cytosolic TGFβ1 protein levels. However, only the TGFβ1 data exhibited statistically significant overexpression, which was proportional to the respective values of mALN diameter of tumor deposits.

Conclusions

Detailed protocol for establishment and fractionation of mALN cell suspension specimens, termed FNCS, into nuclear and cytosolic extracts is here described for the first time. This approach might be a convenient ex vivo model for simultaneous analysis of protein, RNA and DNA biomarkers from nuclear/cytosolic extracts of the same mALN tissue sample. It might have potential to enable, in the age of genomics and personalized medicine, an identification of novel mALN biomarkers and thus improve the screening, diagnosis and prognosis of invasive BC.

The influence of IL1RN VNTR polymorphism on HPV infection among some tribal communities

Persistent infection of human Papillomavirus is the main etiological factor for cervical cancer. Austro-Asiatic tribes are early settlers in India and they have unique genetic variations compared to other people. The immunological response is crucial for the prevention of viral associated diseases. Interleukin-1 receptor antagonist (IL-1RN) is considered being an important regulator of host immune surveillance. A total of 45 Santali tribal women and 10 Kora tribal women were enrolled in the present study and demographic variables were recorded during collection. Genomic DNA was extracted from cervical/vaginal swab samples. IL1RN variable number of tandem repeats (VNTR) polymorphisms and HPV types were determined by PCR-based assay. Association between IL1RN VNTR polymorphisms with the HPV infections among the tribal communities was determined by logistic regression analysis. HPV18 prevalence was significantly higher among tribal women. We observed that the polymorphism A2*A2 (p = 0.022; odds ratio [OR] (95% confidence interval [CI]) = 0.16 (0.03-0.86)] were more resistant to oncogenic HPV infection. Use of oral contraceptives was associated with higher relative risk (p = 0.008; OR [95% CI] = 5.39 [1.47-19.8]) for oncogenic HPV18 positivity among the tribal women. The A2 allele homozygosity of IL1RN VNTR was identified to be associated with the protection from oncogenic HPV infection among various tribal communities of West Bengal and therefore may be a useful marker of host immune response among them.

Semi-supervised training of deep convolutional neural networks with heterogeneous data and few local annotations: An experiment on prostate histopathology image classification

Convolutional neural networks (CNNs) are state-of-the-art computer vision techniques for various tasks, particularly for image classification. However, there are domains where the training of classification models that generalize on several datasets is still an open challenge because of the highly heterogeneous data and the lack of large datasets with local annotations of the regions of interest, such as histopathology image analysis. Histopathology concerns the microscopic analysis of tissue specimens processed in glass slides to identify diseases such as cancer. Digital pathology concerns the acquisition, management and automatic analysis of digitized histopathology images that are large, having in the order of 100^'000² pixels per image. Digital histopathology images are highly heterogeneous due to the variability of the image acquisition procedures. Creating locally labeled regions (required for the training) is time-consuming and often expensive in the medical field, as physicians usually have to annotate the data. Despite the advances in deep learning, leveraging strongly and weakly annotated datasets to train classification models is still an unsolved problem, mainly when data are very heterogeneous. Large amounts of data are needed to create models that generalize well. This paper presents a novel approach to train CNNs that generalize to heterogeneous datasets originating from various sources and without local annotations. The data analysis pipeline targets Gleason grading on prostate images and includes two models in sequence, following a teacher/student training paradigm. The teacher model (a high-capacity neural network) automatically annotates a set of pseudo-labeled patches used to train the student model (a smaller network). The two models are trained with two different teacher/student approaches: semi-supervised learning and semi-weekly supervised learning. For each of the two approaches, three student training variants are presented. The baseline is provided by training the student model only with the strongly annotated data. Classification performance is evaluated on the student model at the patch level (using the local annotations of the Tissue Micro-Arrays Zurich dataset) and at the global level (using the TCGA-PRAD, The Cancer Genome Atlas-PRostate ADenocarcinoma, whole slide image Gleason score). The teacher/student paradigm allows the models to better generalize on both datasets, despite the inter-dataset heterogeneity and the small number of local annotations used. The classification performance is improved both at the patch-level (up to κ=0.6127±0.0133 from κ=0.5667±0.0285), at the TMA core-level (Gleason score) (up to κ=0.7645±0.0231 from κ=0.7186±0.0306) and at the WSI-level (Gleason score) (up to κ=0.4529±0.0512 from κ=0.2293±0.1350). The results show that with the teacher/student paradigm, it is possible to train models that generalize on datasets from entirely different sources, despite the inter-dataset heterogeneity and the lack of large datasets with local annotations.

What is the state of the art of computer vision-assisted cytology? A Systematic Literature Review

Cytology is a low-cost and non-invasive diagnostic procedure employed to support the diagnosis of a broad range of pathologies. Cells are harvested from tissues by aspiration or scraping, and it is still predominantly performed manually by medical or laboratory professionals extensively trained for this purpose. It is a time-consuming and repetitive process where many diagnostic criteria are subjective and vulnerable to human interpretation. Computer Vision technologies, by automatically generating quantitative and objective descriptions of examinations' contents, can help minimize the chances of misdiagnoses and shorten the time required for analysis. To identify the state-of-art of computer vision techniques currently applied to cytology, we conducted a Systematic Literature Review, searching for approaches for the segmentation, detection, quantification, and classification of cells and organelles using computer vision on cytology slides. We analyzed papers published in the last 4 years. The initial search was executed in September 2020 and resulted in 431 articles. After applying the inclusion/exclusion criteria, 157 papers remained, which we analyzed to build a picture of the tendencies and problems present in this research area, highlighting the computer vision methods, staining techniques, evaluation metrics, and the availability of the used datasets and computer code. As a result, we identified that the most used methods in the analyzed works are deep learning-based (70 papers), while fewer works employ classic computer vision only (101 papers). The most recurrent metric used for classification and object detection was the accuracy (33 papers and 5 papers), while for segmentation it was the Dice Similarity Coefficient (38 papers). Regarding staining techniques, Papanicolaou was the most employed one (130 papers), followed by H&E (20 papers) and Feulgen (5 papers). Twelve of the datasets used in the papers are publicly available, with the DTU/Herlev dataset being the most used one. We conclude that there still is a lack of high-quality datasets for many types of stains and most of the works are not mature enough to be applied in a daily clinical diagnostic routine. We also identified a growing tendency towards adopting deep learning-based approaches as the methods of choice.

Variations of Mesozoic feathers: Insights from the morphogenesis of extant feather rachises

The rachises of extant feathers, composed of dense cortex and spongy internal medulla, are flexible and light, yet stiff enough to withstand the load required for flight, among other functions. Incomplete knowledge of early feathers prevents a full understanding of how cylindrical rachises have evolved. Bizarre feathers with unusually wide and flattened rachises, known as "rachis-dominated feathers" (RDFs), have been observed in fossil nonavian and avian theropods. Newly discovered RDFs embedded in early Late Cretaceous Burmese ambers (about 99 million year ago) suggest the unusually wide and flattened rachises mainly consist of a dorsal cortex, lacking a medulla and a ventral cortex. Coupled with findings on extant feather morphogenesis, known fossil RDFs were categorized into three morphotypes based on their rachidial configurations. For each morphotype, potential developmental scenarios were depicted by referring to the rachidial development in chickens, and relative stiffness of each morphotype was estimated through functional simulations. The results suggest rachises of RDFs are developmentally equivalent to a variety of immature stages of cylindrical rachises. Similar rachidial morphotypes documented in extant penguins suggest that the RDFs are not unique to Mesozoic theropods, although they are likely to have evolved independently in extant penguins.

Stable and discriminating features are predictive of cancer presence and Gleason grade in radical prostatectomy specimens: a multi-site study

Site variation in fixation, staining, and scanning can confound automated tissue based image classifiers for disease characterization. In this study we incorporated stability into four feature selection methods for identifying the most robust and discriminating features for two prostate histopathology classification tasks. We evaluated 242 morphology features from N = 212 prostatectomy specimens from four sites for automated cancer detection and grading. We quantified instability as the rate of significant cross-site feature differences. We mapped feature stability and discriminability using 188 non-cancerous and 210 cancerous regions via 3-fold cross validation, then held one site out, creating independent training and testing sets. In training, one feature set was selected only for discriminability, another for discriminability and stability. We trained a classifier with each feature set, testing on the hold out site. Experiments were repeated with 117 Gleason grade 3 and 112 grade 4 regions. Stability was calculated across non-cancerous regions. Gland shape features yielded the best stability and area under the receiver operating curve (AUC) trade-off while co-occurrence texture features were generally unstable. Our stability-informed method produced a cancer detection AUC of 0.98 ± 0.05 and increased average Gleason grading AUC by 4.38%. Color normalization of the images tended to exacerbate feature instability.

Prostate Cancer: A Correlative Study of Multiparametric MR Imaging and Digital Histopathology

Purpose To correlate multiparametric magnetic resonance (MR) imaging and quantitative digital histopathologic analysis (DHA) of the prostate. Materials and Methods This retrospective study was approved by the local institutional review board and was HIPAA compliant. Forty patients (median age, 60 years; age range, 44-71 years) who underwent prostate MR imaging consisting of T2-weighted and diffusion-weighted (DW) MR imaging along with subsequent robot-assisted radical prostatectomy gave informed consent to be included. Whole-mount tissue specimens were obtained with a patient-specific mold, and DHA was performed to assess the lumen, epithelium, stroma, and epithelial nucleus. These DHA images were registered with MR images and were correlated on a per-voxel basis. The relationship between MR imaging and DHA was assessed by using a linear mixed-effects model and the Pearson correlation coefficient. Results T2-weighted MR imaging, apparent diffusion coefficient (ADC) of DW imaging, and high-b-value DW imaging were significantly related to specific DHA parameters (P < .01). For instance, lumen density (ie, the percentage area of tissue components) was associated with T2-weighted MR imaging (slope = 0.36 ± 0.05 [standard error], γ = 0.35), ADC (slope = 0.47 ± 0.05, γ = 0.50), and high-b-value DW imaging (slope = -0.44 ± 0.05, γ = -0.44). Differences between regions harboring benign tissue and those harboring malignant tissue were observed at MR imaging and DHA (P < .01). Gleason score was significantly associated with MR imaging and DHA parameters (P < .05). For example, it was positively related to high-b-value DW imaging (slope = 0.21 ± 0.16, γ = 0.18) and negatively related to lumen density (slope = -0.19 ± 0.18, γ = -0.35). Conclusion Overall, significant associations were observed between MR imaging and DHA, regardless of prostate anatomy. ^© RSNA, 2017 Online supplemental material is available for this article.

An alternative reference space for H&E color normalization

Digital imaging of H&E stained slides has enabled the application of image processing to support pathology workflows. Potential applications include computer-aided diagnostics, advanced quantification tools, and innovative visualization platforms. However, the intrinsic variability of biological tissue and the vast differences in tissue preparation protocols often lead to significant image variability that can hamper the effectiveness of these computational tools. We developed an alternative representation for H&E images that operates within a space that is more amenable to many of these image processing tools. The algorithm to derive this representation operates by exploiting the correlation between color and the spatial properties of the biological structures present in most H&E images. In this way, images are transformed into a structure-centric space in which images are segregated into tissue structure channels. We demonstrate that this framework can be extended to achieve color normalization, effectively reducing inter-slide variability.

Automated prostate tissue referencing for cancer detection and diagnosis

Background

The current practice of histopathology review is limited in speed and accuracy. The current diagnostic paradigm does not fully describe the complex and complicated patterns of cancer. To address these needs, we develop an automated and objective system that facilitates a comprehensive and easy information management and decision-making. We also develop a tissue similarity measure scheme to broaden our understanding of tissue characteristics.

Results

The system includes a database of previously evaluated prostate tissue images, clinical information and a tissue retrieval process. In the system, a tissue is characterized by its morphology. The retrieval process seeks to find the closest matching cases with the tissue of interest. Moreover, we define 9 morphologic criteria by which a pathologist arrives at a histomorphologic diagnosis. Based on the 9 criteria, true tissue similarity is determined and serves as the gold standard of tissue retrieval. Here, we found a minimum of 4 and 3 matching cases, out of 5, for ~80 % and ~60 % of the queries when a match was defined as the tissue similarity score ≥5 and ≥6, respectively. We were also able to examine the relationship between tissues beyond the Gleason grading system due to the tissue similarity scoring system.

Conclusions

Providing the closest matching cases and their clinical information with pathologists will help to conduct consistent and reliable diagnoses. Thus, we expect the system to facilitate quality maintenance and quality improvement of cancer pathology.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1086-6) contains supplementary material, which is available to authorized users.

Intestinal CYP3A4 protects against lithocholic acid-induced hepatotoxicity in intestine-specific VDR-deficient mice

Vitamin D receptor (VDR) mediates vitamin D signaling involved in bone metabolism, cellular growth and differentiation, cardiovascular function, and bile acid regulation. Mice with an intestine-specific disruption of VDR (Vdr(ΔIEpC)) have abnormal body size, colon structure, and imbalance of bile acid metabolism. Lithocholic acid (LCA), a secondary bile acid that activates VDR, is among the most toxic of the bile acids that when overaccumulated in the liver causes hepatotoxicity. Because cytochrome P450 3A4 (CYP3A4) is a target gene of VDR-involved bile acid metabolism, the role of CYP3A4 in VDR biology and bile acid metabolism was investigated. The CYP3A4 gene was inserted into Vdr(ΔIEpC) mice to produce the Vdr(ΔIEpC)/3A4 line. LCA was administered to control, transgenic-CYP3A4, Vdr(ΔIEpC), and Vdr(ΔIEpC)/3A4 mice, and hepatic toxicity and bile acid levels in the liver, intestine, bile, and urine were measured. VDR deficiency in the intestine of the Vdr(ΔIEpC) mice exacerbates LCA-induced hepatotoxicity manifested by increased necrosis and inflammation, due in part to over-accumulation of hepatic bile acids including taurocholic acid and taurodeoxycholic acid. Intestinal expression of CYP3A4 in the Vdr(ΔIEpC)/3A4 mouse line reduces LCA-induced hepatotoxicity through elevation of LCA metabolism and detoxification, and suppression of bile acid transporter expression in the small intestine. This study reveals that intestinal CYP3A4 protects against LCA hepatotoxicity.

CYP2E1-dependent elevation of serum cholesterol, triglycerides, and hepatic bile acids by isoniazid

Isoniazid is the first-line medication in the prevention and treatment of tuberculosis. Isoniazid is known to have a biphasic effect on the inhibition-induction of CYP2E1 and is also considered to be involved in isoniazid-induced hepatotoxicity. However, the full extent and mechanism of involvement of CYP2E1 in isoniazid-induced hepatotoxicity remain to be thoroughly investigated. In the current study, isoniazid was administered to wild-type and Cyp2e1-null mice to investigate the potential toxicity of isoniazid in vivo. The results revealed that isoniazid caused no hepatotoxicity in wild-type and Cyp2e1-null mice, but produced elevated serum cholesterol and triglycerides, and hepatic bile acids in wild-type mice, as well as decreased abundance of free fatty acids in wild-type mice and not in Cyp2e1-null mice. Metabolomic analysis demonstrated that production of isoniazid metabolites was elevated in wild-type mice along with a higher abundance of bile acids, bile acid metabolites, carnitine and carnitine derivatives; these were not observed in Cyp2e1-null mice. In addition, the enzymes responsible for bile acid synthesis were decreased and proteins involved in bile acid transport were significantly increased in wild-type mice. Lastly, treatment of targeted isoniazid metabolites to wild-type mice led to similar changes in cholesterol, triglycerides and free fatty acids. These findings suggest that while CYP2E1 is not involved in isoniazid-induced hepatotoxicity, while an isoniazid metabolite might play a role in isoniazid-induced cholestasis through enhancement of bile acid accumulation and mitochondria β-oxidation.

Multimodal microscopy for automated histologic analysis of prostate cancer

Background

Prostate cancer is the single most prevalent cancer in US men whose gold standard of diagnosis is histologic assessment of biopsies. Manual assessment of stained tissue of all biopsies limits speed and accuracy in clinical practice and research of prostate cancer diagnosis. We sought to develop a fully-automated multimodal microscopy method to distinguish cancerous from non-cancerous tissue samples.

Methods

We recorded chemical data from an unstained tissue microarray (TMA) using Fourier transform infrared (FT-IR) spectroscopic imaging. Using pattern recognition, we identified epithelial cells without user input. We fused the cell type information with the corresponding stained images commonly used in clinical practice. Extracted morphological features, optimized by two-stage feature selection method using a minimum-redundancy-maximal-relevance (mRMR) criterion and sequential floating forward selection (SFFS), were applied to classify tissue samples as cancer or non-cancer.

Results

We achieved high accuracy (area under ROC curve (AUC) >0.97) in cross-validations on each of two data sets that were stained under different conditions. When the classifier was trained on one data set and tested on the other data set, an AUC value of ~0.95 was observed. In the absence of IR data, the performance of the same classification system dropped for both data sets and between data sets.

Conclusions

We were able to achieve very effective fusion of the information from two different images that provide very different types of data with different characteristics. The method is entirely transparent to a user and does not involve any adjustment or decision-making based on spectral data. By combining the IR and optical data, we achieved high accurate classification.

Rifampicin-activated human pregnane X receptor and CYP3A4 induction enhance acetaminophen-induced toxicity

Acetaminophen (APAP) is safe at therapeutic levels but causes hepatotoxicity via N-acetyl-p-benzoquinone imine-induced oxidative stress upon overdose. To determine the effect of human (h) pregnane X receptor (PXR) activation and CYP3A4 induction on APAP-induced hepatotoxicity, mice humanized for PXR and CYP3A4 (TgCYP3A4/hPXR) were treated with APAP and rifampicin. Human PXR activation and CYP3A4 induction enhanced APAP-induced hepatotoxicity as revealed by hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities elevated in serum, and hepatic necrosis after coadministration of rifampicin and APAP, compared with APAP administration alone. In contrast, hPXR mice, wild-type mice, and Pxr-null mice exhibited significantly lower ALT/AST levels compared with TgCYP3A4/hPXR mice after APAP administration. Toxicity was coincident with depletion of hepatic glutathione and increased production of hydrogen peroxide, suggesting increased oxidative stress upon hPXR activation. Moreover, mRNA analysis demonstrated that CYP3A4 and other PXR target genes were significantly induced by rifampicin treatment. Urinary metabolomic analysis indicated that cysteine-APAP and its metabolite S-(5-acetylamino-2-hydroxyphenyl)mercaptopyruvic acid were the major contributors to the toxic phenotype. Quantification of plasma APAP metabolites indicated that the APAP dimer formed coincident with increased oxidative stress. In addition, serum metabolomics revealed reduction of lysophosphatidylcholine in the APAP-treated groups. These findings demonstrated that human PXR is involved in regulation of APAP-induced toxicity through CYP3A4-mediated hepatic metabolism of APAP in the presence of PXR ligands.

C/EBP Homologous Protein (CHOP) Is Crucial for the Induction of Caspase-11 and the Pathogenesis of Lipopolysaccharide-Induced Inflammatio

C/EBP homologous protein (CHOP)/growth arrest and DNA damage-inducible gene 153 is a C/EBP family transcription factor which is involved in endoplasmic reticulum (ER) stress-mediated apoptosis. To determine whether the ER stress-CHOP pathway is involved in the pathogenesis of the lung inflammation, mice were given LPS intratracheally. Treatment with LPS induced mRNAs for CHOP and BiP. The LPS-induced inflammation in lung, including the IL-1beta activity in bronchoalveolar lavage fluid, was attenuated in the Chop knockout mice. Caspase-11, which is needed for the activation of procaspase-1 and pro-IL-1beta, was induced by LPS treatment in the lung and primary cultured macrophages. The induction of caspase-11 by LPS was suppressed in Chop knockout mice. Caspase-11 was also induced by such ER stress inducers as thapsigargin or tunicamycin. These results show that CHOP plays a crucial role in the pathogenesis of inflammation through the induction of caspase-11.

Traditional staining for routine diagnostic pathology including the role of tannic acid. 1. Value and limitations of the hematoxylin-eosin stain

The components of the hematoxylin and eosin (H & E) stain (i.e. hemalum and eosin Y), their contributions to the typical staining pattern, and the reasons why the H & E stains are the preferred oversight stains for routine diagnostic histopathology are discussed. The essential diagnostic significance of effective nuclear staining by hemalum, providing information on nuclear morphology and texture, is emphasized; as is the ironic advantage for routine diagnostic histopathology of the limited range of colors provided by H & E staining, that allows recognition of significant features under low microscopic magnifications. Standardization of hemalum is considered, along with probable reasons why users show resistance to such a concept. Counterstaining with anionic (acid) dyes is discussed, as is the important phenomenon of contrast. The particular advantages and disadvantages of eosin Y and phloxin B as counterstains to hemalum are outlined. The concept of an "ideal routine histological stain" is considered, and H & E is compared to such an ideal case. Finally, deficiencies of H & E staining are discussed, and a program to develop an improved oversight stain is introduced.

A modification of the staining technique of reticular fibres for image analysis of the cardiac collagen network

INTRODUCTION

Silver stain of reticular fibres demonstrates the fine structure of the cardiac collagen network. However, nuclei are also stained with current techniques, a drawback that makes computer image analysis difficult. To solve this problem our study was designed to modify Gomori's method. Reactive concentrations and action times represent the core of that modification. Only stromal tissue is stained. The technique was tested for repeatability and reproducibility to assess the precision of the measurement procedure in the assessment of myocardial collagen in a consecutive series of myocardial samples from patients with and without heart muscle disease. In addition, we checked the reliability of the method by comparing our results with the point-counting method (PCM).

METHODS

The right ventricular myocardium was fixed in 10% buffered formaldehyde and routinely processed. Paraffin sections (4 microm) were stained with several modifications of Gomori's method. Variable concentrations of potassium permanganate, silver solutions and different oxidation times were tried. A field from each sample was digitized. Additionally, the technique was tested for repeatability and reproducibility.

RESULTS

We obtained absence of background and nuclear staining together with a highly contrasted image of the collagen network with 3 min oxidation with 2% potassium permanganate and a silver concentration of 1% during 5 min. In this way, it was very easy to perform acquisition, thresholding and area measurement without any further manual processing of the image.

CONCLUSIONS

This technique appears very helpful for the quantitative study of the cardiac collagen network by means of computerized image analysis systems.

Standardization in biological staining. The influence of dye manufacturing

The purpose of biological staining is to obtain specimens of biological material that can be assessed in the microscope. These specimens are influenced by all processes from removal from the intact organism to mounting on the microscopic slide. To achieve comparable results with various techniques for biological staining, standardization of all procedures and reagents is mandatory. In this paper, I focus particularly on dyes and consider the possibilities for obtaining standardized dyes. In general practice, most biological staining takes place with available commercial dyes. These dyes may or may not have been subjected to quality assessment either internally by the producer or vendor or externally by independent investigators or organizations such as the Biological Stain Commission. Concerted attempts at standardization in Europe are discussed. The latest results of this work, the European standard EN 12376, is presented. This standard is concerned with information supplied by the manufacturer with in vitro diagnostic reagents for biological staining. The standard has been prepared by a Working Group on Staining in Biology under Technical Committee 140, In Vitro Medical Devices, of the European committee for standardization, CEN.

pH-zone-refining countercurrent chromatography

A recently developed preparative technique, pH-zone-refining countercurrent chromatography (CCC), separates organic acids and bases according to their pKa and hydrophobicity. The hydrodynamic mechanism of pH-zone-refining CCC is illustrated in two elution modes along with a simple mathematical analysis. Separations include acidic and basic derivatives of amino acids and peptides, hydroxyxanthene dyes, alkaloids, indole auxins, and structural and geometrical isomers. In addition, recently developed affinity ligand separations of enantiomers, polar catecholamines, and free peptides are also described. Technical guidance is provided for interested users so that they can conduct a systematic search for the optimum solvent system and experimental conditions. Advantages as well as limitations of the present technique are discussed.

Preparative separation of components of the color additive D&C Red No. 28 (phloxine B) by pH-zone-refining counter-current chromatography

A pH-zone-refining counter-current chromatographic method was developed for the preparative (multigram) separation and purification of components of the commercial color additive D&C Red No. 28 (phloxine B). The chromatography of 3 and 6 g of color additive yielded 1.07 and 4.06 g, respectively, of pure 2',4',5',7'-tetrabromo-4,5,6,7-tetrachlorofluorescein, the principal component of D&C Red No. 28. The importance of the quantity of retainer acid (trifluoroacetic acid) relative to the amount of salt in the color additive is discussed.

Standardization of reagents and methods used in cytological and histological practice with emphasis on dyes, stains and chromogenic reagents

The need for the standardization of reagents and methods used in the histology laboratory is demonstrated. After definitions of dyes, stains, and chromogenic reagents, existing standards and standards organizations are discussed. This is followed by practical instructions on how to standardize dyes and stains through the preparation of reference materials and the development of chromatographic methods. An overview is presented of the problems concerned with standardization of the Romanowsky-Giemsa stain for cytological and histological application. Finally, the problem of how to convince routine dye and stain users of the need for standardization in their histology laboratories is discussed.

Standardization of staining in glycosaminoglycan histochemistry: alcian blue, its analogues, and diamine methods

Glycosaminoglycans are identified in tissue sections by various histochemical techniques including staining with alcian blue and its analogues, such as cuprolinic blue and cupromeronic blue, or with high and low iron diamine methods. The variation in staining results in particularly confusing in the case of alcian blue, where not only are several different brands of alcian blue available but also several different staining protocols are used. If the results obtained by these techniques are compared, they often do not match. We have developed a dot blot technique for quality control of glycosaminoglycan histochemistry to standardize the staining protocols. This staining technique enables histochemists to test particular batches of alcian blue or its analogues for selective glycosaminoglycan staining, thus improving control of histochemical results. The results obtained using the dot blot assay indicate that it is necessary to test each batch of dye individually to obtain valid results in glycosaminoglycan histochemistry.

Improving biological dyes and stains: quality testing versus standardization

This paper discusses the impact of both standardization and quality testing of dyes and stains in biology and medicine. After the brief review of why standardized dyes and strains are not presently available commercially, two types of testing and ways of improving dye quality are described. National or international organizations could be established to define standardization of dyes and stains. Standardization would be specifically defined as a list of physico-chemical parameters such as elaborated in this paper. Commercial batches of comparable quality may be labeled by the supplier as "standard dye," a procedure currently performed by the European Council for Clinical and Laboratory Standardization (ECCLS). Also recommended to improve dye quality is commercial dye testing by independent laboratories with subsequent certification for use. This sort of quality control is currently carried out in the United States by the Biological Stain Commission (BSC). The advantages and disadvantages of both techniques and the use of image analysis for the definition of standards are discussed. A combination of both the BSC testing protocols and the ECCLS standards should be established for extended quality control of biological dyes and stains.