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Biomedical subjects

A Leathem

Publications and source records attributed to A Leathem.

17 recordsLinked to original sources
PubMed1994

Helix pomatia agglutinin binding is a useful prognostic indicator in colorectal carcinoma.

BACKGROUND: Most deaths from colorectal carcinoma are due to metastases. A relatively reliable prognostic indicator at surgery to date is the Dukes' stage, but this is a morphologic approach that does not elucidate biochemical changes to explain why cells became metastatic. The binding sites for the lectin from the Roman snail Helix pomatia (HPA) were shown to be good prognostic indicators in breast and gastric cancer, and accordingly, this study was performed to evaluate the use of HPA binding sites as prognostic markers in colorectal carcinoma. METHODS: The histochemically detected expression of HPA binding sites in colorectal carcinomas (n = 130) was increased. The results of the histochemical findings were correlated with patient survival and tumor recurrence. RESULTS: The results indicated that the prognosis for the groups of patients whose colorectal cancer cells binded to HPA in tissue sections was almost as bad as those with Dukes' Stage C disease. CONCLUSION: Because HPA binds to N-acetylgalactosamine, the authors' results indicate that this sugar residue is at least partly involved in the process of human colorectal carcinoma cells metastasizing to regional lymph nodes and possibly also to distant sites.

Acetylgalactosamine↗
PubMed1992

Helix pomatia lectin binding pattern of brain metastases originating from breast cancers.

The glycosylation pattern of brain metastases originating from primary breast carcinomas was investigated using Helix pomatia agglutinin (HPA), a lectin which recognises N-acetyl-galactosamine (GalNac) residues of glycoconjugates. In a previous retrospective study this lectin was shown to label only those primary breast cancers that metastasised. To explore this as a clinical marker of metastatic breast cancer behaviour it is necessary to analyse the HPA binding pattern of metastases to see if this differs from primary cancers. To test the question if brain metastases commitently retain this trait of metastatic primary tumors, we studied Helix pomatia binding pattern of brain metastases removed by surgical excision and immediately fixed and processed. Brain metastases from 16 patients with breast cancer were obtained, 13/16 metastases showed binding to the cytoplasm in the majority of cancer cells, 3/16 did not show binding to cancer cells. Normal adjacent brain showed binding to red blood cells, to capillary endothelium of several biopsies and to rare neurones; this binding did not relate to cancer cell binding. Therefore we conclude that HPA is a relatively stable marker for metastasizing breast cancer cells.

Animals↗
PubMed1989

Change in glycoconjugate for the binding site of the lectin Ulex europeus 1 following malignant transformation of prostatic epithelium.

Immunoperoxidase techniques were used to detect Ulex europeus (UEA1) binding sites on benign and malignant prostatic epithelium. Formalin-fixed, paraffin-embedded (FFPE) and cryostat sections were compared. In benign epithelium, less than 10% of cells on FFPE sections but between 50 and 90% of cells on cryostat sections expressed UEA1 binding sites. In malignant epithelium, more than 90% of cells bound UEA1, irrespective of whether FFPE or cryostat sections were used. Lipid solvents are required for FFPE (but not cryostat) processing and may cause glycolipid extraction. Glycoproteins are not affected. These results suggest that the UEA1 binding site is predominantly glycolipid-based in benign prostatic epithelium but, following malignant transformation, becomes predominantly glycoprotein-based.

Aged↗
PubMed1987

Carbohydrate residues in non-malignant prostatic epithelium as revealed by lectins.

Non-neoplastic prostatic epithelium from 39 patients obtained at transurethral resection for outflow tract obstruction and 5 normal prostates from men under 35 years of age obtained at postmortem were formalin-fixed and paraffin-embedded. The distribution of 8 lectin receptors were studied using a peroxidase anti-peroxidase method and an avidin-biotin method. Con A, WGA, and PNA bound to most epithelial cells. Con A and WGA also showed major stromal binding. Approximately 5% to 10% of cells bound UEA1, GS1, DBA, SBA and BPA. No major differences in lectin receptor expression were observed between normal and hyperplastic epithelium with either of the immunohistochemical techniques except that hyperplastic cells stained more strongly than normal epithelium.

Adult↗
PubMed1987

Enzyme binding to detect carbohydrate expression in tissue sections. 1. Native and cross-linked glucose oxidase.

Enzymes may be useful as highly specific histochemical probes to identify and localize macromolecular substrates in tissue sections. We have used glucose oxidase, a double-headed enzyme, to demonstrate beta-glucosyl groups in paraffin sections. Native glucose oxidase has two active sites per molecule. Soluble polymers formed by glutaraldehyde combine many active binding sites on to one molecule. Some of these bind to glucose in tissue sections, leaving others free to react with chromogenic substrate. The intensity of staining is directly related to the concentration of enzyme, duration of incubation with enzyme, temperature and pH. Polymeric forms of enzyme are about 100 times more effective than native. Glucose oxidase, particularly in a polymeric form, appears a simple reagent for the identification of glucose-containing structures. The use of native and polymerized enzymes as a histochemical probe has enormous potential in the analysis of normal tissues and in the detection of aberrant carbohydrate deposition in pathological tissues; this system serves as a useful model.

Animals↗
PubMed1987

Detection of blood group antigens in frozen sections of prostatic epithelium.

The detection of blood group antigens (BGA) in non-malignant prostates by previous workers has been at best inconsistent. BGA have not before been detected in prostatic carcinomas. In this preliminary study, a variety of anti-BGA reagents, with known specificities that involve the carbohydrate backbone in addition to the BGA specific terminal monosaccharides, were used to study the expression of the A and H (O) BGA in cryostat sections of 16 patients with benign prostatic disease and nine with prostatic cancer. Positive staining, appropriate to the patients' blood group, was seen in all of the benign tissues when anti-BGA reagents that included specificity against type 2 backbone structures were used. Staining was absent, however, if the reagent had only type 1 specificity. The anti-A and anti-H (O) reagents which gave the best staining patterns in benign tissues were used in malignant tissues. No cancer was found to express A antigen but eight of the nine prostatic cancers were positive for the H (O) antigen irrespective of blood group. Using fresh frozen material and appropriate reagents, BGA may be reproducibly detected in the epithelium of all non-malignant prostates, suggesting that a significant component of BGA is probably lipid-based on type 2 carbohydrate backbone chains. Further studies of changes in BGA expression in prostatic cancer are warranted.

ABO Blood-Group System↗
PubMed1983

Lectin binding to formalin-fixed paraffin sections.

Lectins are potentially useful tools in histopathology for the identification of carbohydrates and distinguishing cells according to their type, differentiation or function. Conjugated to fluorescent or enzyme labels, lectins are simple to use on fresh tissue but fixation and processing sequesters glycoconjugates and dissolves out fat-linked sugars. We describe here the use of labelled antibodies to lectins to localise sites of lectin binding and increase sensitivity, combined with trypsin and neuraminidase to reveal sequestered carbohydrates. Absorbing lectins with appropriate sugars establishes the specificity of binding and allows lectins to be used as sensitive and specific reagents.

Binding Sites↗
PubMed1982

Neurone specific enolase: an aid to the diagnosis of melanoma and neuroblastoma.

Melanoma and neuroblastoma are diagnosed by their clinical and histological features, including evidence of melanogenesis and neural differentiation respectively, by tumour cells. These criteria are occasionally inadequate. Melanoma and neuroblastoma are derived from a system of cells characterized by the content, precursor uptake and decarboxylation of particular amines (APUD cells). Neurone specific enolase (NSE) has been proposed as a specific marker for neural elements and APUD cells. Immunohistochemical cytoplasmic and fibrillary localization of this enzyme was demonstrated in formalin-fixed, paraffin-processed sections of melanoma and neuroblastoma, constituting and additional aid to the identification of these tumours. The demonstration of an enzyme of the glycolytic pathway within tumour cells has implications following the effects of anti-tumour agents and these are discussed.

APUD Cells↗
PubMed1982

Somatostatin: a paracrine contribution to hypothyroidism in Hashimoto's thyroiditis.

Thyroid tissue from 18 consecutive cases of Hashimoto's thyroiditis treated surgically were stained immunohistochemically for neurone specific enolase (NSE), somatostatin, calcitonin and thyroglobulin. Cells staining for NSE and somatostatin were present in 14 cases. In four cases large numbers of cells including oxyphil cells stained for NSE. Consecutive sections showed an identical staining pattern of these cells for somatostatin. Sections stained for calcitonin showed few or no positively staining cells. There were moderate numbers of NSE and somatostatin-containing cells in five of the cases, occasional cells in five and none in four cases. Electron microscopy confirmed neurosecretory-like granules within positively staining cells. Somatostatin is known to inhibit T3 and T4 production or release from thyroid cells by a direct action. We suggest, in Hashimoto's disease, somatostatin in paracrine cells serves as a local inhibitory neuroendocrine effector and could be causally related to the hypothyroid state.

APUD Cells↗
PubMedDate not supplied

Lectin binding to normal and malignant breast tissue.

The major carbohydrate groups expressed by normal breast epithelium and primary breast cancers were identified by lectins, using an immunoperoxidase method on paraffin sections. All the lectins (pokeweed, lotus, wheatgerm, peanut, helix, bandeiraea 1, soybean and concanavalin A) bound to breast cancer cells with a variable cytoplasmic, luminal surface or intercellular pattern. Not all cancer cells bound lectins, suggesting sub-populations within individual tumours. On normal breast sections all lectins, with the exception of concanavalin A, bound to the luminal surface of the lining epithelial cells or to myoepithelial cells and showed some differences between acinar and ductal epithelium. The main difference in lectin binding between normal and malignant cells was the transition from luminal surface to cytoplasmic binding to lectins by cancers. In addition, quantitative differences were noted, particularly for concanavalin A which bound to cancer cells but not to normal epithelium.

Binding Sites↗