Acridinium ester conjugated to lectin as chemiluminescent histochemistry marker

Lectin-carbohydrate complex evaluation by chemiluminescence

In order to characterize the affinity between specific carbohydrate-binding proteins such as lectins, a model is proposed to study these interactions using a polysaccharide membrane to simulate such adsorption. Here, lectin-carbohydrate interactions were chemiluminescently investigated using lectins conjugated to acridinium ester (AE) and polysaccharides composed of their respective specific carbohydrates. The lectin-AE conjugates were incubated with discs (0.0314-0.6358 cm²) of phytagel, chitosan and carrageenan. The complex formation chemiluminescently detected followed the Langmuir isotherm from which constants were estimated. The association constant (K_a) and maximum binding sites on the membranes were 2.4 × 10^-7 M^-1 ± 0.8 × 10^-7 M^-1 and 1.3 × 10^-3 mol. mg^-1 ± 0.3 × 10^-3 mol. mg^-1 (Con A); 0.9 × 10^-6 M^-1 ± 0.4 × 10^-6 M^-1 and 0.021 × 10^-3 mol. mg^-1 ± 0.003 × 10^-3 mol. mg^-1 (WGA) and 2.0 × 10^-6 M^-1 ± 0.9 × 10^-6 M^-1 and 0.069 × 10^-3 mol. mg^-1 ± 0.010 × 10^-3 mol. mg^-1 (PNA). The proposed model might be useful to study binding affinity and estimate the amount of binding not limited by the sugar content in the membrane.

Glycomic profile of the human parotid gland between 18th and 26th week of fetal development

The formation of new and functional structural components of several organs, such as parotid glands, can be influenced by the glycocode. This study analyzed the glycobiology of parotid salivary gland tissue during fetal development using specific biochemical probes (lectins and antibodies). Eleven parotid gland samples from human fetuses were obtained from spontaneous abortions at 14-28 weeks of gestation, and tissue sections were analyzed for lectin histochemistry and immunohistochemistry. From the 18th to 26th week, Canavalia ensiformis agglutinin, wheat germ agglutinin, Ulex europaeus agglutinin-I, peanut agglutinin, Sambucus nigra agglutinin, and Vicia villosa agglutinin lectin staining were predominantly observed in the apical and/or basement membranes of the ducts and tubulo-acinar units. Moreover, the presence of galectin-1 was found in the membrane, cytoplasm, and nucleus of both structures. Conversely, Gal-3 and mucin-1 were restricted to the glandular ducts. The lectin staining pattern changed during the weeks evaluated. Nevertheless, the carbohydrate subcellular localization represented a key factor in the investigation of structural distribution profiles and possible roles of these glycans in initial parotid gland development. These findings are defined by their high biological value and provide an important base for the development of subsequent studies. (J Oral Sci 58, 353-360, 2016).

Brain effects of the lectin from Canavalia ensiformis in adult rats previously suckled in favorable and unfavorable conditions: A spreading depression and microglia immunolabeling study

OBJECTIVE

To evaluate in adult rats, previously suckled under favorable and unfavorable conditions, the brain electrophysiological and microglial effects of the treatment early in life with the lectin (ConA) from Canavalia ensiformis.

METHODS

Male Wistar newborn rats (n = 89) were suckled under favorable or unfavorable conditions, represented by litters with 6-7 pups or 12-14 pups (groups N6 and N12, respectively). From postnatal days 5-24, they were treated intraperitoneally with 1 or 10 mg/kg ConA (groups L1 and L10, respectively), or with saline solution (group Sal), or no treatment (group Naïve). At 90-120 days of age, cortical spreading depression (CSD) was recorded at two parietal points for 4 hours, and CSD parameters (velocity of propagation and amplitude and duration of the DC slow potential change) were measured. Fixative-perfused brain sections were reacted with anti-Iba1 antibodies to quantify immunolabeled microglia.

RESULTS

Compared with the control groups, ConA-treated animals dose-dependently presented with reduced CSD propagation velocities and increased amplitude and duration of the CSD slow potential change. Microglia Iba-1 immunoreactivity was lower in both nutritional groups treated with ConA, in comparison with the control groups. The CSD hemisphere presented with higher immunoreactivity compared with the CSD-free hemisphere.

DISCUSSION

Attenuation in CSD propagation and microglia reaction was associated in adulthood with ConA treatment during brain development, indicating that the lectin can affect the electrophysiological and microglial development, and suggesting long-lasting protective action of the lectin on the rat brain, which is not impeded by the unfavorable suckling condition.

Con A conjugated to Europium(III) cryptate as a new histological tool for prostate cancer investigation using confocal microscopy

Lectins are carbohydrate recognition proteins that can be used as probes to reveal the glycosylation state of cells. They frequently have been used for diagnostic and prognostic cancer studies. For fluorescence based analysis, lectins commonly are conjugated to fluorescein isothiocyanate (Con A-FITC); however, this molecule loses its fluorescence quickly. We conjugated Europium cryptate to Con A (Con A-cryp-Eu) for use as a histochemical luminescent probe to recognize glucose/mannose residues in benign prostatic hyperplasia and prostatic carcinoma tissues, and used confocal microscopy instead of commercial Con A-FITC. Tissues were treated with Evans blue to suppress intrinsic tissue fluorescence before incubation with Con A-cryp-Eu or Con A-FITC. Con A-cryp-Eu exhibited hemagglutinating activity. Con A-cryp-Eu showed the same binding pattern as Con A-FITC in prostate stroma and gland cells. Staining was strong in benign prostate hyperplasia and prostate carcinoma tissues. Con A-cryp-Eu probe stained glucose/mannose residues in prostatic carcinoma more intensely than Con A-FITC. Furthermore, staining with Con A-cryp-Eu showed greater fluorescence intensity than Con A-FITC and the emission of Con A-cryp-Eu was more stable than the Con A-FITC for seven days under the same storage conditions. Maintenance of the luminescent properties and the binding pattern of Con A-cryp-Eu favor its use as an auxiliary histochemistry probe for prostatic tissue studies.

Glycophenotype evaluation in cutaneous tumors using lectins labeled with acridinium ester

Background. Tumor cells show alterations in their glycosylation patterns when compared to normal cells. Lectins can be used to evaluate these glycocode changes. Chemiluminescence assay is an effective technique for quantitative analysis of proteins, nucleic acids, and carbohydrates due to its high sensitivity, specificity, and rapid testing. Objective. To use histochemiluminescence based on lectin conjugated to acridinium ester (AE) for the investigation of glycophenotype changes in cutaneous tumors. Methods. Concanavalin A (Con A), Peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), and Maackia amurensis agglutinin (MAA) were conjugated to acridinium ester. Biopsies of cutaneous tumors and normal skin were incubated with the lectins-AE, and chemiluminescence was quantified and expressed as Relative Light Units (RLU). Results. Actinic keratosis (AK), keratoacanthoma (KA), squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) showed lower expression of α-D-glucose/mannose and α-L-fucose residues compared to normal tissue. Cutaneous tumors displayed higher expression of Gal-β(1-3)-GalNAc residues than normal tissue. AK and SCC exhibited higher expression of Neu5Ac-α(2,3)Gal residues than normal epidermis. KA and BCC showed equivalent RLU values compared to normal tissue. Conclusions. Lectin histochemiluminescence allowed quantitative assessment of the carbohydrate expression in cutaneous tissues, contributing to eliminate the subjectivity of conventional techniques used in the histopathological diagnosis.

Chemiluminescent detection of carbohydrates in the tumoral breast diseases

Nowadays, there is an increase of investigations into the fibroadenoma, mainly because some studies have shown that the occurrence of fibroadenoma is linked to an increased risk of developing breast carcinoma. Currently, the chemiluminescence biomarkers are applied for validation methods and screening. Here, a lectin chemiluminescence is proposed as new histochemistry method to identify carbohydrates in mammary tumoral tissues. The lectins concanavalin A (Con A) and peanut agglutinin (PNA) conjugated to acridinium ester were used to characterize the glycocode of breast tissues: normal, fibroadenoma, and invasive duct carcinoma (IDC). The lectin chemiluminescence expressed in relative light units (RLU) was higher in fibroadenoma and IDC than in normal tissue for both lectins tested. The relationship RLU emission versus tissue area described a linear and hyperbolic curve for IDC and fibroadenoma, respectively, using Con A whereas hyperbolic curves for both transformed tissues using PNA. RLU was abolished by inhibiting the interaction between tissues and lectins using their specific carbohydrates: methyl-α-D: -mannoside (Con A) and galactose (PNA). The intrinsic fluorescence emission did not change with combination of the lectins (Con A/PNA) to the acridinium ester for hydrophobic residues. These results represent the lectin chemiluminescence as an alternative of histochemistry method for tumoral diagnosis in the breast.

1H and 13C NMR spectra, structure and physicochemical features of phenyl acridine-9-carboxylates and 10-methyl-9-(phenoxycarbonyl)acridinium trifluoromethanesulphonates--alkyl substituted in the phenyl fragment

The 1H and 13C NMR spectra of twelve phenyl acridine-9-carboxylates--alkyl-substituted in the phenyl fragment--and their 10-methyl-9-(phenoxycarbonyl)acridinium salts dissolved in CD3CN, CD3OD, CDCl3 and DMSO-d6 were recorded in order to examine the influence of the structure of these compounds and the properties of the solvents on chemical shifts and 1H-(1)H coupling constants. Experimental data were compared with 1H and 13C chemical shifts predicted at the GIAO/DFT level of theory for DFT(B3LYP)/6-31G** optimised geometries of molecules, as well as with values of 1H chemical shifts and 1H-(1)H coupling constants, estimated using ACD/HNMR database software to ensure that the assignment was correct. To investigate the relations between chemical shifts and selected structural or physicochemical characteristics of the target compounds, the values of several of these parameters were determined at the DFT or HF levels of theory. The HOMO and LUMO energies obtained at the HF level yielded the ionisation potentials and electron affinities of molecules. The DFT method provided atomic partial charges, dipole moments, LCAO coefficients of pz LUMO of selected C atoms, and angles reflecting characteristic structural features of the compounds. It was found that the experimentally determined 1H and 13C chemical shifts of certain atoms relate to the predicted dipole moments, the angles between the acridine and phenyl moieties, and the LCAO coefficients of the pz LUMO of the C atoms believed to participate in the initial step of the oxidation of the target compounds. The spectral and physicochemical characteristics of the target compounds were investigated in the context of their chemiluminogenic ability.

ConA and UEA-I lectin histochemistry of parotid gland mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) corresponds to 5-12% of all salivary gland tumours, and is classified as low, intermediate or high grade. Traditionally, immunohistochemistry was considered as the complementary tool for diagnosis of salivary gland neoplasia. Lectin histochemistry has also been increasingly used in recent years. In this work, lectins were used as histochemical markers for normal and transformed parotid glands. Biopsy specimens of 15 cases diagnosed as MEC (low, intermediate and high grade) of the parotid gland were trypsin- and methanol-H(2)O(2)-treated and incubated with horseradish peroxidase (HRP)-conjugated lectins, Concanavalin A (Con A-HRP) and Ulex europeus I (UEA-I-HRP). Con A stained the neoplasic cells of MEC (all grades). In high and intermediate cases, ductal cells were weakly stained by Con A. UEA-I weakly stained normal cells of the excretory duct and neoplasic cells in high grade. Neoplasic cells in intermediate grade were moderately stained and in low grade, the cell membrane was intensely stained with UEA-I. Stroma presented a direct relation between malignancy and staining intensity for UEA-I. The results indicated that lectin histochemistry distinguished the cell biology among histological grades of MEC.