Biomedical subjects

H Lyon

Publications and source records attributed to H Lyon.

At least 19 recordsLinked to original sources

PubMed2003

Estimation and tests of haplotype-environment interaction when linkage phase is ambiguous.

In the study of complex traits, the utility of linkage analysis and single marker association tests can be limited for researchers attempting to elucidate the complex interplay between a gene and environmental covariates. For these purposes, tests of gene-environment interactions are needed. In addition, recent studies have indicated that haplotypes, which are specific combinations of nucleotides on the same chromosome, may be more suitable as the unit of analysis for statistical tests than single genetic markers. The difficulty with this approach is that, in standard laboratory genotyping, haplotypes are often not directly observable. Instead, unphased marker phenotypes are collected. In this article, we present a method for estimating and testing haplotype-environment interactions when linkage phase is potentially ambiguous. The method builds on the work of Schaid et al. [2002] and is applicable to any trait that can be placed in the generalized linear model framework. Simulations were run to illustrate the salient features of the method. In addition, the method was used to test for haplotype-smoking exposure interaction with data from the Childhood Asthma Management Program.

Algorithms↗

PubMed2000

Comparative localization of cathepsin B protein and activity in colorectal cancer.

Cathepsin B is a lysosomal cysteine proteinase that may participate in cancer progression. We compared localization of its protein and activity during progression of human colorectal cancer. In adenomas and carcinomas, protein expression and, particularly, activity were elevated compared with those in normal colorectal mucosa. In normal mucosa, cathepsin B protein expression was moderate in stroma and variable in epithelium, whereas activity was mainly present in distinct areas of stroma directly underneath the surface of the colon and in epithelium at the surface of the colon. Stroma in adenomas and carcinomas contained moderate to high protein levels but little activity except for areas of angiogenesis, inflammation, and necrosis, in which activity was high. In adenomas and the majority of well-differentiated carcinomas and moderately differentiated carcinomas, cathepsin B protein and activity were found in granular form in the epithelium, close to the basement membrane. Protein and activity levels were low and diffusely distributed in cancer cells in the remainder of the well-differentiated and moderately differentiated carcinomas and in all poorly differentiated carcinomas. Invasive fronts in most cancers contained moderate protein levels but high activity. We conclude that (a) activity localization is essential to understand the role of cathepsin B in cancer progression, and (b) cathepsin B activity in human colon is associated with invasion of cancer cells, endothelial cells, and inflammatory cells, and in cell death, both apoptotic and necrotic.

Adenomatous Polyps↗

PubMed2000

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.

Animals↗

PubMed1999

Prognostic estimation of survival of colorectal cancer patients with the quantitative histochemical assay of G6PDH activity and the multiparameter classification program CLASSIF1.

Prognosis of colorectal cancer patients that show similar histopathology may vary substantially. An attempt was made to improve prognosis by the self-learning classification program CLASSIF1, based on automated multiparameter analysis of quantitative histochemical and clinical parameters of 64 colorectal carcinomas and adjacent normal mucosae. The histochemical parameters applied were the oxygen-insensitivity assay of glucose-6-phosphate dehydrogenase (G6PDH) activity, a valid discriminator between normal and cancerous mucosae, and related parameters CuZn- and Mn-superoxide dismutase (SOD) levels, and lipid peroxidation (LPO) capacity. Data were processed on the basis of a postoperative follow-up of minimally 32 and maximally 56 months. CLASSIF1 selected the parameters oxygen insensitivity of G6PDH activity, CuZn-SOD and Mn-SOD levels, LPO capacity, lymph node metastasis, Dukes' stage, and age for the highest prognostic value. On the basis of these selected parameters, CLASSIF1 correctly predicted favorable outcome in 100% of the surviving patients and fatal outcome in 64% of the deceased patients. G6PDH activity appeared to be the major information carrier for CLASSIF1. On the basis of G6PDH activity parameters alone, 96% of the surviving patients and 55% of the deceased patients were correctly classified. In comparison, estimation of prognosis on the basis of Dukes' stage alone resulted in 71% correctly classified surviving patients and 61% of patients who died. It is concluded that the self-learning classification program CLASSIF1, on the basis of quantitative histochemical and clinical parameters, is the best prognostic estimator for colon cancer patients yet available.

Adult↗

PubMed1997

Expression of CuZn- and Mn-superoxide dismutase in human colorectal neoplasms.

Decreased intracellular SOD protein levels and activity have been related with malignancy in the past. To investigate their relevance in the carcinogenetic process in the colon, we determined quantitatively CuZn-SOD and Mn-SOD levels and total SOD activity by histochemical means in human normal colorectal mucosa, adenomas, and carcinomas. Protein levels and activity were significantly decreased in carcinomas. CuZn-SOD protein levels, but not Mn-SOD levels or total SOD activity were related with differentiation grade and to a lesser extent with Dukes stage. Moderately differentiated carcinomas and Dukes stage A carcinomas showed lowest levels. Some carcinomas expressed elevated levels of CuZn-SOD and this was an indication of poor survival. It is concluded that decreased SOD expression is not a prognostic marker and seems to be a secondary phenomenon rather than directly linked with the carcinogenetic process.

Adenocarcinoma↗

PubMed1997

Commercial formalin substitutes for histopathology.

We compared the performance of six commercial fixatives proposed to be formalin substitutes with the performance of buffered formalin, Clarke's ethanol-acetic acid, and ethanol, using rat liver, small intestine, and kidney. We investigated the rate of penetration, mode of fixation, extent of protein and structural immobilization, quality of histology and cellular structure following routine dehydration and paraffin embedding, and performance as a fixative for immunohistochemistry. Furthermore, we evaluated the effects of the various fixatives on ultrastructure. Only buffered formalin performed equally well on all tissues tested. While several of the commercial fixatives appeared to preserve liver tissue at 200x, the preservation of kidney, intestinal villi, and smooth muscle was unacceptable. Histological distortion, cell shrinkage and vacuolization were prominent when the substitutes or ethanol were used. In contrast, these artifacts were found occasionally and to a minor degree when buffered formalin or Clarke's fixative were used. Immunohistochemistry demonstrated a total loss of low molecular weight antigens for all fixatives except buffered formalin. The best immunostaining was obtained by combining formalin fixation with antigen retrieval. We conclude that none of the proposed commercial substitutes for buffered formalin are adequate for critical histology or histopathology.

Animals↗

PubMed1995

Non-hazardous organic solvents in the paraffin-embedding technique: a rational approach. Aliphatic monoesters for clearing and dewaxing: butyldecanoate.

The aim of this study was to substitute hazardous compounds, used in tissue processing and dewaxing, with compounds having lowest possible toxicity and inflammability without impairing the morphology, staining characteristics, or diagnostic value of the tissue sections. All aromatic compounds and aliphatic hydrocarbons (e.g. alkanes, isoparaffins, petroleum distillates, etc.) were rejected, primarily due to their high vapour pressure. Based on a theoretical study of compounds used for clearing, a number of non-hazardous potential substitutes were chosen. The following experimental study narrowed the group to three unbranched, saturated, aliphatic monoesters containing 12-14 carbon atoms. On large-scale testing of these compounds, we found butyldecanoate to be the closest to an ideal substitute for aromatic and aliphatic hydrocarbons in the histology department: the section quality is at least equal to that obtained with xylene. For dewaxing, it is used at 30-35 degrees C. Butyldecanoate is not suitable as a pre-mounting agent. In practice, this is no problem as modern mounting agents permit mounting of coverslips directly from ethanol without impairing the appearance of the section in the microscope. Butyldecanoate has only a slight odour, insignificant vapour pressure (< 0.01 kPa at 20 degrees C), and does not present a fire hazard (flash point 134 degrees C). The introduction of this compound in the laboratory poses no health hazard, and the substance is biodegradable.

Animals↗

PubMed1994

Synovial sarcoma. An immunohistochemical study of the epithelial component.

Twenty-five synovial sarcomas were studied with a battery of antibodies directed against keratin and epithelial membrane antigen (EMA). The keratin antibody MNF 116 showed reactivity in 24 tumors. In addition, 22 tumors showed reactivity with the antibody Keratin Wide Spectrum, 20 with the antibody Keratin 56, 64, and 19 with CAM 5.2. Seventeen tumors showed reactivity with EMA. The keratin and EMA reactivity was present in cells lining obvious cleft-like structures in biphasic tumors. In the spindle cell areas of both biphasic and monophasic fibrous tumors, we found clusters of a few reacting cells apparently located around small clefts. In the synovioblastic tumors, clusters of plump tumor cells reactive for both the keratins and EMA were present. In conclusion, we found that proper identification of epithelial differentiation in synovial sarcomas is facilitated by an immunohistochemical application of anti-epithelial antibodies. In most tumors, there was immunoreactivity for the same type of keratins as are normally identified in simple epithelia (the antibody CAM 5.2), but also for those found in stratified squamous epithelia (the antibody Keratin 56, 64). The results indicate that screening for epithelial features on paraffin sections in the various types of synovial sarcoma, even the poorly differentiated synovioblastic tumors, is improved if epithelial antibodies with a broad spectrum of reactivity are chosen.

Antibodies↗

PubMed1993

Deposition of C3, the terminal complement complex and vitronectin in primary biliary cirrhosis and primary sclerosing cholangitis.

Characteristics of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are bile duct destruction and portal inflammation. Increased levels of circulating complement activation products are also present. This raises the possibility of involvement of complement-dependent cytotoxic mechanisms in the pathogenesis. Therefore, we investigated liver biopsy specimens from 21 patients with PBC, six patients with PSC and six controls for complement deposits by immunohistochemistry using polyclonal and monoclonal antibodies against C3d, the terminal complement complex (TCC) and vitronectin (S-protein). We found C3d, TCC and vitronectin deposits only in the portal tracts. C3d and TCC were present in the walls of the hepatic arteries and in the connective tissue stroma but never around the bile ducts. We found vitronectin deposits throughout the connective tissue, often independent of the TCC deposits. When vitronectin and TCC were co-localized, the staining patterns were inverse; that is, intense staining for TCC accompanied weak staining for vitronectin and vice versa. Occasionally complete dissociation between TCC and vitronectin staining was observed. Deposits of TCC and vitronectin showed a focal distribution leaving many portal tracts free of TCC. Our results question whether complement-dependent cytotoxic mechanisms take part in the bile duct destruction in PBC and PSC.

Adult↗

PubMed1991

Gallocyanin chromalum as a nuclear stain in cytology. I. A cytophotometric comparison of the Husain-Watts Gallocyanin chromalum staining protocol with the Feulgen procedure.

In the present study, the staining characteristics of the Gallocyanin chromalum technique devised by Husain and Watts are compared with the Feulgen reaction. Liver imprints, blood smears, and cervical smears were fixed in ethanol and stained with either the Husain and Watts Gallocyanin chromalum reagent or the Feulgen-Schiff reagent. The slides were then post-treated with 70% ethanol-HCl pH 1.0, or with phosphotungstic acid for 0.5-30 min. The integrated optical density of cell nuclei was measured with a VIDAS image analyzer. In the material stained with the Husain and Watts procedure, some Gallocyanin chromalum was removed from the nuclei in the early phase (5 min) of all the post-treatment steps, followed by a plateau phase where the integrated optical density remained constant for 30 min. In this phase, the nuclear absorbance was highly reproducible and of the same size regardless of the post-treatment. Both the Husain and Watts procedure and the Feulgen-reaction gave quantitative staining of DNA. The Gallocyanin chromalum stain after Husain and Watts is a quick staining procedure for quantitative evaluation of DNA in cytological material. Proper rinsing of the slides is necessary for a good reproducibility of results.

Blood Cells↗

PubMed1991

Clogging of biliary endoprostheses. A morphologic and bacteriologic study.

The main problem encountered with the use of biliary endoprostheses is their tendency to clog, which necessitates their exchange. We studied this problem by performing light and electron microscopy and bacterial cultures on both unused and clinically used endoprostheses. These examinations showed several basic defects in their manufacture, such as irregular inner surfaces and badly constructed side holes. The deposit that ultimately led to their occlusion was found mainly to be concentrated around the side holes. Minimizing the amount of material, bacteria, and plant fibres adhering to the endoprosthesis is the desired goal and may be achieved by improving their manufacture and design.

Bacteria↗

PubMed1989

The correlation between uptake of methyl green and Feulgen staining intensity of cell nuclei. An image analysis study.

Paraffin sections of rat tissue fixed in either formaldehyde solution (3.6% w/v) or in Carnoy's fluid were stained using standardized Methyl Green-Pyronin procedures with the dyes used either simultaneously or in sequence. The sections were evaluated for the uptake of the two dyes by cell nuclei, nucleoli and cytoplasm using colour TV-image analysis. The parameters measured were integrated optical density and the surface area of the object. The sections were then destained and a Feulgen reaction was performed. The coordinates of the cells measured after the simultaneous Methyl Green-Pyronin method were stored in the computer, making it possible to measure the same cells in the Feulgen-restained sections. Image analysis gave results which invalidate the sequential methods as opposed to the simultaneous method. Mean optical densities were significantly increased for both dyes with the simultaneous method after formaldehyde fixation as compared to Carnoy fixation. The quantitative correlation of Methyl Green and DNA in the simultaneous technique was found to parallel exactly that of the Feulgen stain. In conclusion, the simultaneous Methyl Green-Pyronin technique is recommended while the sequential methods seem to be of less value.

Animals↗

PubMed1988

Electrically-induced collagen calcification in pig skin. A histopathologic and histochemical study.

Deposition of calcium salts on collagen fibres in skin of fully anaesthetized pigs was induced by exposure to direct current (d.c.). In biopsies obtained from cathode areas successively from day 1 to day 7 after exposure the histopathologic and histochemical changes before and after the initial deposition of calcium salts have been examined. For comparison skin sites with intradermal injected calcium hydroxyapatite crystals were studied in addition. Small areas of calcified collagen and elastic fibres were noted in viable tissue 2 days after d.c. exposure. In succeeding days the calcified areas enlarged with new deposits always more superficial and closer to the epidermis than the original calcium deposits. Preconditions for calcification appear to be (1) a pH change in basic direction and/or the electrochemical processes specific to the cathode area and (2) a viable tissue. Elastic fibres appear to have a lower calcification threshold than collagen fibres. A positive staining for glycoproteins (PAS) and glycosaminoglycans (alcian blue pH 2.5) was noted in the calcified collagen fibres simultaneously with the calcification. In succeeding days the intensity of the staining reactions increased. Whether changes in the glycoproteins, collagen and its intimately bound glycosaminoglycans precede the calcification or the staining reactions develop secondarily to this deposition is not known. However, seven days after intradermal injections of Ca-apatite crystals in pig skin small and large crystals were observed ultrastructurally without any relation to collagen fibrils, but the calcified tissue presented a positive PAS and alcian blue reaction from day 2. Thus the PAS and alcian blue stainings in this model develop secondary to the deposition of calcium salts.

Animals↗

PubMed1988

Staining of the nucleolus with protein and RNA stains for automatic measurement of nucleolar size in paraffin sections.

In this paper two staining methods for automatic assessment of nucleolar profile area in paraffin sections of breast carcinomas using the IBAS 2000 image analyzer are reported. In the first method, the nucleolar proteins are stained with phloxine B, in the second the nucleolar RNA is stained with methyl green-pyronin. Both methods are fully reproducible. Statistically, the profile areas observed for the same patient by the two methods were found not to differ significantly. Because of their rigidity and their size in relation to section thickness, nucleoli are particularly attractive cell structures for quantitation, for instance in studies of variables that might be useful in establishing the prognosis for carcinoma patients.

Breast Neoplasms↗

PubMed1986

Nucleic acid staining with the methyl green-pyronin method. A comparison of the use of pure dyes and commercially available dyes.

We compared the staining obtained using commercially available pyronin Y samples with that obtained using pure pyronin Y in a standardized methyl green-pyronin procedure. In addition, the importance of the dye content of the anhydrous dye was investigated by varying the dye content by the addition of pure pyronin Y to one of the commercially available pyronin Y samples. We found that, for routine histological work, commercially available pyronin Y samples may produce acceptable results provided the sample can be shown by spectrophotometry to contain at least 43% pyronin Y.

Animals↗

PubMed1986

Purification of methyl green using polyamide.

Explore the source record for details and available documents.

Animals↗

PubMed1986

The blood hepatocytic barrier: a light microscopical, transmission- and scanning electron microscopic study.

The normal blood hepatocytic barrier (BHB), comprised by the endothelial lining cells and the perisinusoidal space, was investigated, and it was concluded that the BHB is a complex structure in which each individual part serves several functions. Immunohistochemical staining for factor VIII showed endothelial lining cells to be positive. By TEM and SEM the endothelial cells were seen to be fenestrated without a basal lamina. They possess numerous endocytotic vesicles. The perisinusoidal space contains the lipocytes and a matrix composed of fibrils, and a microfilamentous to granular material. The nature of these matrix components was poorly analyzable by conventional methods. Lipocytes were visualized by LM in: sections stained with oil red 0 after fixation in Baker's formol-calcium and following post-fixation in dichromate, and toluidine-blue-stained Epon-embedded sections. TEM revealed numerous cytoplasmic processes rich in microfilaments encircling the sinusoids.

Azo Compounds↗

PubMed1985

Tubular carcinoma of the breast. A long term follow-up.

The aim of this study is to provide a long-term follow-up of patients with tubular carcinoma and to investigate whether the separation of the mixed type of tubular carcinoma, tubular component more than 75%, from invasive ductal carcinoma with a major tubular component (ductal carcinoma MTC), tubular component 50 to 75%, is supported by long term follow-up. For this study 388 consecutive breast carcinomas were selected from the files of the Department of Pathology, Bispebjerg Hospital, Denmark for the years: 1956-59. Twenty tubular carcinomas were found and 16 ductal carcinomas MTC were also identified. For each patient with tubular carcinoma and ductal carcinoma MTC, two controls with ductal carcinoma NOS were selected. The patients in these four groups were followed until 1 April 1982. None of the patients were lost to follow-up. Among the 20 patients with tubular carcinoma, 10 died within this period compared to 37 of the 40 controls. Of the 16 patients with ductal carcinoma MTC, 15 died compared to 29 of the 32 controls. The difference in Kaplan-Meier survival curves between the tubular carcinomas and their controls is highly significant. There is no significant difference between ductal carcinomas MTC and their controls. These findings are not changed significantly when 5, 10, and 20 year survival rates are corrected for expected survival. This study demonstrates long-term survival for patients with tubular carcinoma as compared to ductal carcinoma NOS. There is no difference in long-term survival between ductal carcinoma MTC, tubular component between 50 and 75%, and ductal carcinoma NOS. It therefore seems appropriate to set 75% tubular component as a reasonable cut-off point for the mixed type of tubular carcinoma.

Adenocarcinoma↗