Chemical and histochemical studies of normal and diseased human gastrointestinal tract. III. Changes in the histochemical and chemical properties of the epithelial glycoproteins in the mucosa close to colonic tumours

CH-overtone regions as diagnostic markers for near-infrared spectroscopic diagnosis of primary cancers in human pancreas and colorectal tissue

We have investigated the application of near-infrared spectroscopy for detection of human primary pancreatic and colorectal cancers. Spectra from cancerous and normal tissue were collected from a total of 37 surgically resected pancreatic and colorectal patient tissue specimens using a fibre-optic probe. Major spectral differences were observed in the CH-stretching first (6,000-5,400 cm(-1)) and second overtone (9,000-7,900 cm(-1)) regions. By use of artificial neural networks, linear discriminant analysis, and cluster analysis as pattern-recognition methods the spectra were classified into cancerous and normal tissue groups with accuracy up to 89%. We also explored differences between the spectra obtained from colorectal and pancreatic tissue. Spectral data from cancerous and normal tissue were classified organ-specifically into four groups with accuracy between 80 and 83%. Our results indicate that CH-overtone regions, besides serving as diagnostic markers for NIR spectroscopic diagnosis of primary human pancreas and colorectal cancers, are also useful for elucidating differences between the spectra obtained from colorectal and pancreatic cancerous tissue.

Ground squirrel model for cholelithiasis: role of epithelial glycoproteins

The cholesterol-fed Richardson's ground squirrel (Spermophilus richardsonii) has proven to be an effective animal model in which to study factors that influence cholesterol gallstone formation and associated alterations in the gallbladder epithelium. Ground squirrels of either sex, fed a 2% cholesterol-enriched diet, exhibit cholesterol monohydrate crystal precipitation within 24 hours and macroscopically visible cholesterol stones by 3 weeks. Data on bile chemistry, biliary cholesterol precipitation, and various mucosal alterations occurring prior to, during, and after stone formation were collected using sampling intervals from 6 hours to 20 weeks on the diet. The results indicate that mucin hypersecretion appears to be more closely related to the initiation of nucleation than does either bile calcium of pH. Mucus hypersecretion begins within 18 hours of diet initiation and continues throughout the 20 week experimental period. Apical excrescences became more common and were larger in size during the early stages of cholelithiasis. Administration of aspirin during the experimental period demonstrated an inhibition of mucin synthesis and release. Gallstones were not formed in these aspirin-treated animals. A lectin-binding panel for 10 epithelial glycoprotein-related sugars indicated the mucin secreted by the gallbladder epithelium of 7 day experimental animals differed from that of controls. The most obvious difference was the abolition of WGA binding in the experimental animals, suggesting an absence of sialic acid expression in the mucin during the lithogenic process. Ultrastructural histochemistry indicated that both sulphomucin and sialomucin were present in the secretory granules and within the surface mucus layer of both experimental and control animals. Experimental animals, however, exhibited a significant predominance for sulphomucin. This pattern varies from that typically seen in other regions of the gastrointestinal tract where sialomucins predominate during pathologic processes.

Monoclonal antibody TKH2 to the cancer-associated epitope sialosyl Tn shows cross-reactivity with variants of normal colorectal goblet cell mucin

It has been suggested that synthesis of mucin-type carbohydrate chains may be arrested at the core structure Tn. This may occur following premature sialylation of Tn giving the structure STn. TKH2, a monoclonal antibody to STn, is regarded as showing highly specific reactivity with colorectal and other epithelial neoplasms. In this study we have shown that TKH2 cross-reacts with normal colorectal goblet cells that are mild PAS positive (specific for non-O-acetylated sialic acid). Approximately 9% of caucasians secrete colorectal mucin in which sialic acid is non-O-acetylated. TKH2 also cross-reacts with mild PAS negative colorectal goblet cells when sections have been pre-treated with potassium hydroxide (to remove O-acetyl groups from sialic acid). These findings make it likely that the usual non-reactivity evidenced by TKH2 for normal colorectal goblet cells is due to the presence of sialic acid that is heavily O-acetylated. The reactivity of TKH2 for colorectal cancer mucin can be readily explained by the loss of sialic acid O-acetyl substituents and not necessarily by incomplete synthesis of mucin-type carbohydrate chains.

Colorectal mucin histochemistry in health and disease: a critical review

Neoplastic, inflammatory and regenerative processes affecting colorectal mucosa are associated with alterations in structure of epithelial mucin. This review collates mucin-, lectin-, and immuno-histochemical observations on colorectal mucins and introduces recent molecular genetic insights into the structure of the protein backbone of mucins. The numerous structural modifications uncovered by the various technical approaches have been reduced to a few manageable principles that are of relevance to both researcher and diagnostic pathologist. Particular attention is drawn to the need to appreciate the limited specificities of probes, the confounding influences of anatomical site and genetic factors (necessitating the use of appropriate positive and negative control tissues) and the precise location of secretory material. In the past, insufficient attention has been given to the effects of altered differentiation including metaplasia and differing lineage expression in epithelial disorders of growth. It is likely that certain changes loosely ascribed to goblet cell mucin, such as neo-expression of blood group antigens and anomalous expression of core carbohydrate structures, do not occur at all. Critical examination of available data point to only two consistent and unequivocal changes affecting goblet cell mucin in pathological processes: loss of O-acetyl substituents at sialic acid C4 and C7,8,9 and increased sialylation. Furthermore, there are no neoplasia-specific alterations in mucins documented to date. All neoplasia-associated changes have been described in non-neoplastic lesions also.

Effects of Yersinia enterocolitica infection on rabbit intestinal and colonic goblet cells and mucin: morphometrics, histochemistry, and biochemistry

The effects of Yersinia enterocolitica on intestinal goblet cells were investigated in New Zealand white rabbits. Animals infected with Y enterocolitica were compared with weight matched and pair fed controls. Goblet cell hyperplasia developed in the distal small intestine of infected rabbits on day 1, in the mid small intestine on day 3, and in the upper small intestine on day 6. In all regions hyperplasia persisted throughout the 14 day study. The degree of hyperplasia was greater in the distal small intestine than the upper and mid regions. Goblet cells in the proximal colon of infected animals seemed to respond as those in the distal small intestine. Thus goblet cell hyperplasia developed more rapidly and to a greater extent in the ileocaecal region where mucosal injury was most severe. These changes resulted directly from Y enterocolitica infection since goblet cell numbers did not increase in pair fed controls. Histochemically, goblet cell mucins from infected rabbits were unchanged at either six or 14 days. Biochemical analysis, however, established that purified mucins from animals on day 6 after infection were less sialylated (in the small intestine) and more sulphated (in the small intestine and proximal colon). In addition, mucins from the distal small intestine and the proximal colon seemed to contain fewer but longer oligosaccharide chains.

Histochemical studies of intestinal epithelial goblet cell glycoproteins during the development of the human foetus

Histochemical studies performed on specimens of intestine from 12 to 37-week human foetuses showed that the epithelial glycoproteins of the goblet cells of the small intestine are non-sulphated sialoglycoproteins containing neutral sugar (hexose, 6-deoxy hexose or N-acetyl hexosamine residues with Periodic acid-Schiff (PAS) reactive vicinal diols), sialic acids without O-acyl substituents, smaller and variable quantities of sialic acids with O-acyl substituents at positions C8 or C9 (or with two or three side chain substituents) and O-acyl sugars (neutral sugars with an ester substituent blocking PAS reactivity). In the lower small intestine glycoproteins containing 8 (or 9)-O-acyl sialic acids are first observed in goblet cells at the tips of the villi. As the foetus matures their quantity increases and they are found in goblet cells located along the length of the villi. Smaller quantities of O-acyl sialic acids and traces of O-acyl sugars occur in the goblet cells of the upper small intestine. The colonic goblet cells contain sulphosialoglycoproteins of two types. The first type, found in the majority of specimens, contains O-sulphate ester, neutral sugar, O-acyl sugars and 8 (or 9)-O-acyl sialic acids. The second type contains O-sulphate ester, neutral sugars, and sialic acids which are either without side chain O-acyl substituents or are a mixture of such acids and 8 (or 9)-O-acyl sialic acids; O-acyl sugars are reduced or absent.(ABSTRACT TRUNCATED AT 250 WORDS)

Colonic epithelium reactive monoclonal antibodies. Identification and immunohistochemical localization of the target epitopes

We have produced a small library of colonic mucosa and colorectal carcinoma reactive monoclonal antibodies (MoAbs) by immunizations with extracts of human colon cancer tissue and a human colon cancer cell line. Hybridoma supernatants were tested on (normal and neoplastic) human tissues by immunoperoxidase methods to evaluate organ or tissue specificity. Initial biochemical characterization of the target antigens was performed by gelpermeation chromatography, Western blotting and competition assays. Based upon the immunoreactivity patterns and the characteristics of the antigen four groups of MoAbs could be distinguished. The first group concerns the antibodies PARLAM 3, 9 and 10. These antibodies react with an 87 kDa protein moiety in high molecular weight (2-5 x 10(6) Da) glycoproteins. In intestinal and colon mucosa these antibodies showed diffuse binding with goblet cells. In colon carcinoma decreased reactivity with these MoAbs was found. The second group consists of antibodies PARLAM 8, 12 and 13. These antibodies react with large (greater than 5 x 10(6) Da) glycoproteins, most likely with carbohydrate epitopes. By immunohistochemistry in normal colon mucosa the antibodies all show granular supranuclear reactivity with goblet cells. These antibodies show increased reactivity with colon adenomas and adenocarcinomas. A third group is formed by PARLAM 2, which also reacts with a large (greater than 5 x 10(6) Da) glycoprotein, showing a granular distribution in goblet cells. In colon carcinomas more extensive expression is found than in normal colonic mucosa. Finally, the fourth group consists of PARLAM 11, which also reacts with a large (greater than 5 x 10(6) Da) glycoprotein, located in the brush border of colonic columnar cells. These antibodies might be useful tools for the analysis of the expression of mucin related glycoproteins in normal, preneoplastic and neoplastic colon mucosa.

Distribution of mucins in the mucosa of the digestive tract of reptiles: a histochemical study

In the present study, the distribution and characteristics of mucins in the digestive tract of 3 reptiles (Lacerta lepida, Mauremys caspica and Testudo graeca) are investigated. In the esophagus of Testudo graeca, both the glands and the mucous cells of the surface epithelium contained sulphosialo-mucins. In Lacerta lepida, esophageal mucous cells contained either-sialo-mucins or sulphosialo-mucins. The esophageal mucous cells of Mauremys caspica contained acidic mucosubstances. The stomach of the species studied revealed a small amount of acidic mucosubstances; in Lacerta lepida and Testudo graeca, abundant neutral mucins were detected. In the intestine, the amount of acidic mucosubstances was increased in a caudal direction, the sulphosialo-mucins being predominant. In conclusion, acid mucins were more abundant in the esophagus and intestine than in the stomach. This may be related to cytoprotective roles in the esophagus and protection against potential pathogens in the intestine.

A new method for the histochemical demonstration of O-acyl sugars in human colonic epithelial glycoproteins

A new general method has been developed for the specific histochemical identification of O-acyl sugars in any epithelial glycoprotein. These sugars include hexose, 6-deoxyhexose and N-acetylhexosamine with an ester substituent(s) located on a potential vicinal diol(s). In the procedure reported [the periodic acid-borohydride reduction-saponification-selective periodate oxidation-borohydride reduction-periodic acid-Schiff (PA-Bh-KOH-PA*-Bh-PAS) method] the initial PA-Bh treatment renders vicinal diols located on either sialic acid or neutral sugars PAS unreactive. In the subsequent steps ester substituents are removed from both O-acyl sugars and O-acyl sialic acids by saponification (KOH), sialic acid vicinal diols are selectively removed by the PA*-Bh sequence and O-acyl sugars are stained with the PAS technique. This method has the advantage that the results are obtained with a single section and the results are either positive or negative. Consequently, it is superior to the three indirect methods investigated because it does not require an observer to compare the intensity or the shade of the staining obtained with serial sections. Using the PA-Bh-KOH-PA*-Bh-PAS method we have demonstrated, for the first time, that O-acyl sugars occur in the epithelial goblet cell glycoproteins of adult human colon. The effect of the presence of O-acyl sugars on the interpretation of a number of other methods for the histochemical investigation of glycoproteins is discussed. It is recommended that the results obtained with the PA-Bh-KOH-PA*-Bh-PAS method be evaluated before histochemical procedures for the investigation of neutral sugars and O-acyl sialic acids are selected.

Characterization of mono-, di-, and tri-O-acetylated sialic acids on human cells

The presence of mono-, di-, and tri-O-acetylated sialic acids on human cells was demonstrated by using radiochromatographic and chemical techniques. Human melanoma cells and fresh colon tissue were biosynthetically labeled with 6- (3H) glucosamine. Radiolabeled sialic acids were hydrolytically removed from cellular glycoconjugates, purified by ion-exchange chromatography, and separated by paper chromatography on the basis of the number of O-substitutions on each sialic molecule. This analytical technique characterized radiolabeled sialic acids that migrated with the same Rf as synthetic mono-, di-, and tri-O-acetylated 14C-labeled sialic acids. The mono-O-acetylated sialic acids were characterized by their sensitivity to sodium periodate oxidation and a crude mouse liver esterase preparation. The di- and tri-O-acetylated sialic acids were characterized by their resistance to sodium periodate oxidation and sensitivity to the action of crude mouse liver esterase. Chromatographically separated di- and tri-O-acetylated sialic acids from normal human colon tissue were characterized by their respective ion molecular weights by using fast-atom bombardment-mass spectrometry. Using these methods, we chemically characterized mono, di-, and tri-O-acetylated sialic acids expressed on human cells. Aberrant expression of O-acetylated sialic acids was associated with adenocarcinoma of the colon, leading to a nearly complete loss of di- and tri-O-acetylated sialic acids.

Colorectal goblet cell mucins in familial adenomatous polyposis

Ninety two tissue blocks from the left colon and 52 from the right colon were obtained from 112 patients with familial adenomatous polyposis (FAP). Tissues from 137 patients with other conditions served as controls. Within the main study a smaller investigation was performed to compare sections from the left and right colon in the same subject. Several well known histochemical techniques were used to investigate possible changes in sulphation, sialic acid structure (loss of O-acetyl substituents), and changes in the ratio of sialic acid to neutral sugars. In patients with FAP, as in controls, there was increased expression of periodic acid Schiff positive mucin and fucose in the right colon. The only difference between patients with FAP and controls was the indirect demonstration of less neutral mucin in the right colon in FAP, but this did not seem to affect neutral sugars binding to UEA-1, PNL, or HPA. As in the general population, a small proportion of patients with FAP showed a lack of O-acetyl substituted sialic acid. Sialic acid heterogeneity probably has a genetic basis, but this is not associated with the genetic defect underlying FAP.

Histochemical procedures for the simultaneous visualization of neutral sugars and either sialic acid and its side chain O-acyl variants or O-sulphate ester. I. Methods based upon the selective periodate oxidation of sialic acids

Five new methods, based upon the selective oxidation of sialic acid residues with 0.4 mM periodic acid in approximately 1 M hydrochloric acid at 4 degree C for 1 h (PA), have been devised for the simultaneous visualization of neutral sugars and either sialic acid and its side chain O-acyl variants or O-sulphate ester. In the first of these, the selective periodate oxidation-borohydride reduction-saponification-selective periodate oxidation-Thionin Schiff-saponification-borohydride reduction-periodic acid-Schiff (PA-Bh-KOH-PA-T-KOH-Bh-PAS) technique, sialic acids with O-acyl substituents at C7, C8 or C9 (or which have two of three side chain O-acyl substituents) stain blue while neutral sugars with periodate-sensitive vicinal diols (hexose, 6-deoxyhexose, and N-acetylhexosamine) stain magenta. The second method, the saponification-selective periodate oxidation-Thionin Schiff-saponification-borohydride reduction-periodic acid-Schiff (KOH-PA-T-KOH-Bh-PAS), stains all sialic acids blue and neutral sugars magenta. In the third procedure, the selective periodate oxidation-Thionin Schiff-borohydride reduction-periodic acid-Schiff-saponification (PA-T-Bh-PAS-KOH) method, sialic acids without side chain substituents (or which have an O-acyl substituent at C7) stain blue and neutral sugars stain magenta. In the fourth method, the saponification-selective periodate oxidation-borohydride reduction-Alcian Blue pH 1.0-periodic acid-Schiff (KOH-PA-Bh-AB1.0-PAS) technique, O-sulphate esters stain aquamarine blue and neutral sugars stain magenta. In all of these techniques mixtures of the components stain in various shades of purple.(ABSTRACT TRUNCATED AT 250 WORDS)

Colorectal goblet cell sialomucin heterogeneity: its relation to malignant disease

Mucus secreted by colorectal cancer differs in three respects from that produced normally: an overall reduction, a loss of O-acetyl substituents in sialic acid, and an increase in neutral mucin. Similar changes have been reported in apparently normal mucosa bordering colorectal cancer. "Normal" left sided colorectal mucosa from 32 patients with rectal cancer was studied. Each case was matched by age and sex to a patient with diverticular disease and a patient with irritable bowel syndrome. Twenty five patients with right sided cancer were matched to patients with Crohn's disease. Sections were stained with mild periodic acid Schiff (mPAS) (selectively stains N-acetyl sialic acid lacking in O-acetyl group) and other closely related techniques. Reactions were graded negative, weak, and intense. An intense reaction was found in 9% of cases; there was no difference between the various matched groups. Phenylhydrazine interposition failed to block the mPAS effect, indicating that a positive result was due to a deficiency of sialic acid with O-acetyl substituents rather than neutral mucin. Different staining patterns in left and right colon were probably due to differing ratios of total sialic acid:fucose. These findings indicate a hitherto unsuspected colorectal goblet cell sialomucin heterogeneity within the general population, but no association with neoplastic disease is apparent.

The histochemical assessment of sulphated and non-sulphated sialomucin in intestinal epithelium

A new method (KOH/AB 1.0/PAPS) for the simultaneous detection of sulphated and non-sulphated sialomucins in intestinal epithelium was compared to the standard high iron diamine/alcian blue(HID/AB) technique. Although there was no difference in the sensitivity of the methods in detecting cells containing only one type of mucin, detection of cells containing both types was twice as effective with the KOH/AB 1.0/PAPS method. This indicates that previous investigations using only HID/AB may have seriously underestimated mucosal non-sulphated mucin content and raises doubts about the validity of some of the conclusions reached concerning the pre-neoplastic potential of 'transitional' mucosa of the colon.

Chemical and histochemical studies of normal and diseased human gastrointestinal tract. V. A differential diagnostic method for the histochemical classification of glycoproteins

A differential diagnostic scheme is described for the division of colonic epithelial glycoproteins into eleven histochemically distinct classes. The scheme depends upon the use of seven histochemical techniques which, collectively, permit the differential staining of O-sulphate ester, sialic acid and its side chain O-acyl variants and vicinal diols located on carbohydrate residues other than sialic acids. Elements of the scheme also provide a general approach to the classification of epithelial glycoproteins in anatomic sites other than the colon. Application of the scheme permitted the classification of the epithelial glycoproteins in the mucosa 0.5-5.0 cm from human colonic tumours and provided direct confirmation of previous observations that changes from normal in the relative proportions of either side chain O-acylated sialic acids or sialic acids and O-sulphate esters can occur independently of one another.